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Chewing side preference as a type of hemispheric laterality
Abstract
Chewing side preference is a factor that could effect prosthodontic treatment. The purpose of this study was to determine whether chewing side was another type of hemispheric lateralization comparable with footedness, handedness, eyedness and earedness. Chewing side preference was tested in 189 subjects of whom 84 were partially edentulous, 98 had a full compliment of dental units (81 included implant-supported restoration restoring the missing teeth and 17 with fully intact dentitions), and seven were fully edentulous, restored with complete dentures. Laterality tests were carried out for the first cycle of mastication, handedness, footedness, earedness and eyedness and patient questionnaire. Most patients preferred chewing on the right side (78b3%) and were right sided. Chewing side preference correlated with other tested hemispherical lateralities. Missing teeth, occlusion type, lateral guidance, gender, implant-supported restorations and complete dentures do not affect the side preference for chewing. This presents a strong argument that chewing side preference is centrally controlled and provides food for thought regarding its significance in prosthodontics.
... While it is often considered a minor aesthetic concern in humans, recent studies suggest that it may be linked to more profound biological processes in vertebrate fetal development such as embryonic exposure [11] and brain laterality [11][12][13][14][15][16][17][18][19]. Teeth asymmetry can indicate asymmetric feeding behavior reflected in the patterns of dental asymmetric wear [22,23], or in tooth emergence and eruption. The latter may provide information on prenatal and early postnatal growth and development [24]. ...
... This study is novel because it is the first to measure teeth asymmetry in reptiles, a trait that reflects multiple forms of stress in other vertebrates. It is consistent with the pattern of morphometric left bias (eye asymmetry, digit asymmetry, supra-and infra-labial asymmetry) and tail injury cited above [18,19,[21][22][23][24]. We specifically test the directional asymmetry (DA) in varanid populations, isolating it from fluctuating asymmetry (FA). ...
... Another aspect to be further investigated is what specifically causes the size asymmetry seen in varanid teeth. The effect of wear on teeth asymmetry is explained by asymmetric feeding behavior, wearing more extensively the dominant side in both humans [22] and extinct durophagous reptiles [23]. However, we suspect that teeth asymmetry is most likely not derived from asymmetric behavior. ...
Stressors such as injuries, embryonic instability during development, and higher levels of stress hormones such as testosterone can result in increases in fluctuating asymmetry in reptiles and other vertebrates. Digit asymmetry, digit ratio variability, and skull trait asymmetry such as eye and jaw size have been correlated with stress level in both snakes and lizards. Teeth asymmetry has also been used as a biomarker for stress and brain laterality. Body size is correlated with many potential stressors, yet there has been little research on how body size in reptiles relates to asymmetry. We investigate teeth asymmetry within the lizard family Varanidae, a clade with a diverse range of sizes consisting of the largest living lizard, Varanus komodoensis. Using a landmark/semi-landmark analysis, we derived Centroid Size for 671 pairs of teeth from 13 varanid species, and asymmetry was derived for each pair. Right-biased asymmetry was significantly greater in the upper tooth row, but breaking up tooth positions into further sections did not yield a significant difference. We found a significant positive linear correlation between body size and right-biased teeth directional asymmetry within Varanus, but only when excluding V. komodoensis. This significant correlation may result from fewer potential predators and more potential food items, thus resulting in less overall stress. When analyzed separately, V. komodoensis individuals with <180 mm head length demonstrated a positive, yet non-significant, trend along a similar trajectory to their congenerics with a high goodness of fit. On the other hand, individuals > 180 mm showed a high degree of scatter, with several specimens having pronounced left-biased asymmetry. We suspect that this dramatic change was due to a combination of ontogenetic niche shift, bigger home ranges, a greater susceptibility to negative anthropogenic influences, and/or a male bias in the bigger specimens sampled, but a larger sample size is required to determine if there is statistical significance in these intra-specific trends. Body asymmetry can reflect brain laterality, which may be a potential driver for the teeth asymmetry seen here.
... Chewing side preference is associated with brain lateralization (Nissan, Gross, Shifman, Tzadok, & Assif, 2004;Serel Arslan et al., 2017), but results from different studies are not consistent. This inconsistency may be due to differences in dental health, undergone procedures and general condition of the oral cavity. ...
... Our results are in partial agreement with the results from a study by Athab Abduljabbar et al. (2022), where the authors found that most participants chewed bilaterally. In our study, bilateral chewing was found in females (about 50 %), while in males, right-side chewing was slightly more frequent, which is consistent with Nissan et al. (2004), whose study participants were also right-handed. The right-handed individuals in our study, especially males, mostly also tended to chew on the right side. ...
... However, there were many females in each category of handedness with a preference for both sides (about 50 %). The fact that chewing side preference is a manifestation of brain laterality is apparent in studies where this preference significantly correlates with other known lateralities (Nissan et al., 2004;Serel Arslan et al., 2017). We found a statistically signifi-cant moderate correlation of chewing side preference with self-reported and calculated handedness, apart from calculated handedness in females, where the correlation was weak. ...
Lateralization manifests as a sensory or muscular preference. These preferences are often crucial for (1) handedness calculation (determined by the Edinburgh Handedness Inventory -EHI) and determination of self-reported handedness, (2) description of the relationship between handedness and different side preferences, specifically footedness, eyedness and chewing side preference. Our sample consisted of 133 laterality and EHI questionnaires filled in by healthy adults (self-reported 72 right-handed, 2 ambidextrous and 59 left-handed). Results showed that self-reported and calculated handedness were in a 100 % agreement for right-handers. There was an approximately 80 % agreement for left-handers, as only 8 individuals were classified as ambidextrous, and 2 individuals were classified as right-handers. There was a strong correlation between EHI activities and handedness. Footedness and chewing side preference showed a moderate correlation with handedness. Eyedness showed only a weak correlation. No significant sex differences were found. In conclusion, a significant relationship between self-reported and calculated handedness was found. Accuracy in categorizing handedness was 100 % for right-handers and 80 % for left-handers. Writing and drawing showed the strongest correlation with handedness, while eye preference had the weakest correlation. A crossed laterality was found more in left-handed individuals.
... Several research papers have indicated a high percentage of patients' preference for unilateral chewing, mainly on the right side [66][67][68][69][70][71]. As early as 1994, the results of international research highlighted the fact that the majority of people are right-handed (85% of study participants) and prefer the right side for performing several activities [36,72]. ...
... The chewing preference for a certain side could be considered similar to the dominant hand use (right-handed, left-handed), the possible origin stemming from the dominant cranial hemisphere [69]. In two Israeli studies from 2004 and 2011, each involving 189 patients, a preference for rightsided chewing was observed in 78% of participants [70,71]. Similarly, an analysis on 146 patients in Barcelona showed that among the patients with preference for unilateral chewing, 77% preferred the right side [73]. ...
... Quite interestingly, in the case of edentate patients, even though the lost teeth are replaced by prosthetic restorations, no bilateral chewing is evident [75]. Chewing side preference does not seem to be influenced by the location of the edentulous site(s), gender, type of occlusion, lateral guidance or the type of prosthetic restoration (e.g., complete dentures or implant-supported restorations) [70,71]. Also, relevant to our results are the findings of some Japanese researchers regarding the fact that patients with unilateral and bilateral missing posterior teeth chewed on one side more predominantly than healthy control individuals . ...
The articular eminence (AE) is part of the temporal component of the temporomandibular joint (TMJ). The inclination of the AE (AEI) has an important role in TMJ biodynamics, influencing the path of movement of the disc-condyle complex. Although AEI values might change due to tooth loss, little is known about what effect could have the loss of occlusal support in the molar area on AE morphology. AEI was measured on cone-beam computed tomography (CBCT) images of 41 patients (82 TMJs) with or without occlusal support in the molar region. The patients included in this study were divided into four groups: (1) patients with maintained occlusal support in the molar areas on both sides (right and left side) (MM); (2) patients with loss of occlusal support in the molar areas on both sides (right and left side) (LL); (3) patients with loss of occlusal support in the molar area only on the right side, but with maintained occlusal support on the left molar area (LM); (4) patients with loss of occlusal support in the molar area only on the left side, but with maintained occlusal support in the right molar area (ML). AEI values were higher in the TMJs on the side with maintained occlusal support in the molar area (M) than the AEI values measured in TMJs from the side with loss of occlusal support in the molar area (L). AEI values on the right side were higher in the MM patients in comparison to the AEI values on the right side of LL patients. The loss of occlusal support in the molar areas changes the mandibular biodynamics, which might be reflected in the morphological changes at the AE level, where it might cause flattening of the articular slope predominantly on the right side.
... There is no consensus on the etiology of unilateral mastication (7). While some studies argue that environmental factors such as missing teeth, teeth with restoration, pain, dental caries and temporomandibular disorder (TMD) affect chewing side preference (6)(7)(8)(9), others claim that brain laterality associated with hand, foot, ear and eye preferences also influences CSP (3,10,11). ...
... The study protocol was approved by the (10,11). ...
... In a study, Fujita et al. (17) of caries, pain and food texture (3,6,7,9,11,29,30). In a study involving 189 individuals from the Israeli population, Nissan et al. (10) investigated chewing side preference using patient questionnaire and the first cycle of gum chewing. The authors reported that local dental parameters such as missing teeth, teeth with implant-supported restoration and complete dentures had no effect on CSP. ...
Objective: The aim of this study was to evaluate the relationship between the direction of unilateral chewing preference observed in fully dentate bruxist and non-bruxist groups (with fully dentate and missing and/or restored teeth) and brain laterality. Methods: Brain laterality of the subjects (n=132) was determined based on responses to questions about extremity and sensory preferences. The reliable visual analogue scale (VAS), Kazazoğlu’s method and the sunflower seed shell cracking test were used to determine chewing side preference. Results: Chewing side preferences determined by VAS were not associated with brain laterality. While extremity and sensory preferences were predominantly right-sided (dominant left hemisphere) in all groups, the frequency of the left side chewing was found to be high only in bruxers (p > 0.05). No significant association was found between the results of VAS and other techniques (p > 0.05). Conclusion: The left chewing side preference is observed more frequently in bruxers, suggesting that different central and peripheral mechanisms may be involved in bruxers.
... 2 The direction toward which a piece of chewing gum placed on the center of the tongue is moved by the patient for the first masticatory cycle has also been used for determining the preferred chewing side. 3,12 A video recording of the mastication movements in the frontal plane was used to examine the mastication pattern. Initially, authors observed the side of the mandible during the closing phase of the first mastication cycle to define the preferred chewing side. ...
... Therefore, studies conducted on completely dentate individuals are not easily comparable. 1,3,4,17 The dental state is expected to influence the preferred chewing side. Specifically, when teeth are missing predominantly on one side, a person is more likely to masticate on the side where natural teeth are present. ...
... Neurological determinants, genetic factors, or an individual's side may have an important influence on function. 3,20 Future research in these areas may help better understand the function of the orofacial system and its relevance for restorative dentistry. ...
... Missing teeth, implant supported restoration, and complete dentures did not affect the chewing side preference. [1] According to the relation of missing teeth to the chewing side preference showed no effect even when teeth were missing on the side of the other preferred lateralities, which presents a strong argument that chewing side preference is centrally controlled. [1,5] Reinhardt et al. proved that signs and symptoms of TMD have been associated with PCS, but no obvious pattern for the localization of the symptoms has been found in those who have a PCS. ...
... [1] According to the relation of missing teeth to the chewing side preference showed no effect even when teeth were missing on the side of the other preferred lateralities, which presents a strong argument that chewing side preference is centrally controlled. [1,5] Reinhardt et al. proved that signs and symptoms of TMD have been associated with PCS, but no obvious pattern for the localization of the symptoms has been found in those who have a PCS. [6] With the study by Miyake, [1] a significant association between clinical/anamnestical unilateral TMJ pain and a PCS was found. ...
... [1,5] Reinhardt et al. proved that signs and symptoms of TMD have been associated with PCS, but no obvious pattern for the localization of the symptoms has been found in those who have a PCS. [6] With the study by Miyake, [1] a significant association between clinical/anamnestical unilateral TMJ pain and a PCS was found. ...
... This is because the neuromuscular system is responsible for the shifting of food from one side to another. When chewing continues, local variables and other factors begin to affect chewing, in which case determination of the PCS becomes more difficult [6,7,24]. ...
... The prevalence of PCS ranges from 45% to 98%, and using the right side instead of the left is much more common among people [5,6,19,24]. However, there are numerous factors affecting PCS. ...
... In addition, adults aged 40-69 years have been found to chew more asymmetrically than younger and older adults [19]. Chewing sidedness is also partly determined by dental status and food texture [5,7,24]. ...
Objective:
To resolve how the preferred chewing side (PCS) affects facial asymmetry in twins, whether there are differences between monozygotic (MZ) and dizygotic (DZ) twins, and whether the twins with PCS have more asymmetric faces compared to symmetrically chewing twins.
Material and methods:
The study included 106 Lithuanian twin pairs of the same sex, 59 MZ and 47 DZ pairs. The data were analysed from facial 3D images and manually added landmarks. 3D images were analysed by Rapidform2006 software and statistical analyses were done by using the R software environment version 4.1.0.
Results:
The contralateral effect of PCS and larger chin side was dominant among right and non-right side chewing twins. Being female increased the whole face symmetry.
Conclusion:
The volume of the chin becomes larger on the side opposite to the twins' habitual chewing side. As the results are quite similar in both twin types, functional factors are more prominent than heredity.
... In the case of differing results, the existence of occlusal contact was reexamined and verified by dental floss placed at the back of the dentition. With the subject in a mouth closure position in lateral excursion, an examiner pulled the floss forward allowing examination of the type of guidance in lateral movement (24) . All recordings were made in the afternoon to avoid possible diurnal variations. ...
... Our findings revealed a preference for the right side in chewing. The generally found marked preference of the right side was confirmed by many studies (5,24,30,41) . The distribution of the chewing side preference of the subjects was in the range of(38-78.3%) ...
... The distribution of the chewing side preference of the subjects was in the range of(38-78.3%) to the right and (13-36%) to the left (4,5,17,18,21,24,30) which is similar to that of our study (78.5 and 21.5%) for the right and left sides respectively. A recent study with 4068 subjects showed rightside PCS dominance of 64% (1188 subjects) (30) . ...
objectives: Would people prefer one-side chewing? Why? Data on the relation of both TMJ and occlusal variables to the preferred chewing side (PCS) are limited in the English literature. This study investigated the prevalence and relation of PCS with both TMJ and occlusal variables. Methods: One hundred and ninety two full-dentate dental professionals (mean age 25 years) participated in a cross-sectional study. Subjective TMJ variables and PCS were evaluated by a questionnaire. Clinical and dental examination was carried out for TMJ and occlusal variables. Chi-Square and fisher-tail tests were used with (p-value ≤ 0.05) considered significant. results: The prevalence of PCS was (62%) of which 78.5% were right-sided chewers and 21.5% left-sided chewers in contrast to non-PCS(38%). PCS was significantly related to subjective clicking sound and muscle pain (P-value < 0.01). Also, PCS was significantly related to TMJ and muscle pain on palpation, TMJ clicking during closing on auscultation and mandibular-deviation (P-value< 0.01). The same trend was identified between PCS and maximum functional-lateral range (P-value<0.01); while this association was insignificant for the presence of slide in centric. Interestingly, canine-guidance subjects prefer bilateral chewing. Conversely, subjects with group-function or have balancing-side contact were significantly related to PCS. Conclusion: TMJ-related variables (click ,TMJ and muscle pain, mandibular-deviation and maximum functional-lateral range) as well as, occlusal-related variables (group function and balancing-side contact) are potential and likely contributing factors in preference of chewing side. Additional studies regarding the effect of these variables on preference of chewing side are recommended.
... The patients were asked if they had a right-or left-sided chewing preference. Their answer was confirmed using the methodology described by Jiang et al and Nissan et al. 17,18 A piece of sugar-free chewing gum was placed on the center of the dorsal surface of the tongue, and the side toward which the chewing gum was taken for the first cycle of mastication was noted. These tests confirmed that 67 patients showed a rightsided chewing preference and 28 showed a left-sided chewing preference. ...
... The presence of a CSP could influence the prosthodontic treatment modality. 18 In patients with a CSP, special attention must be paid to biomechanical factors such as providing the proper ferrule effect, maintaining an adequate crown-root ratio, providing proper resistance and retention form, selecting suitable restorative materials, and selecting the proper form and location of implants. ...
... This concept is supported by a previous study reporting that a chewing preference results in a unilateral enlargement of the masseter muscle on the dominant side. 18 An age range of 20-35 years was selected as an inclusion criterion to obtain a patient population that was fully dentate. In addition, according to Bokhari et al, individuals older than 40 years are 4 times more likely to have periodontitis. ...
Occlusion and chewing-side preference (CSP) are complex aspects of the stomatognathic system. The present study aimed to record the difference in bite force between the dominant and nondominant chewing sides of patients with a CSP. A sample of 95 subjects (aged 20-35 years) with established CSPs was selected. Measurements of bite force on both sides of the jaw were recorded while the subjects were seated in an upright, forward-looking, unsupported natural position. The recordings of each subject were accomplished in a single session with a portable customized bite recording sensor, and the maximal voluntary bite force (MVBF) value was recorded in newtons. The MVBF data were compared in pairs (dominant vs nondominant side; men vs women; and age < 30 vs ≥ 30 years) with independent-samples t tests. The combined mean (SD) MVBF for men and women was 694.73 (110.47) N on the dominant chewing side and 507.20 (86.76) N on the nondominant chewing side. In the male group, the mean MVBF was significantly greater (P < 0.0001) on the dominant chewing side (755.73 N) than on the nondominant chewing side (548.10 N). Similarly, in the female group, the mean MVBF was significantly greater (P < 0.0001) on the dominant chewing side (620.95 N) than on the nondominant chewing side (457.74 N). Furthermore, the differences between the male and female dominant sides and between the male and female nondominant sides were statistically significant (P < 0.0001). However, there was no statistically significant difference in bite force between the age groups (P > 0.05).
... Most people chew more on one particular side, that is, the right side [21][22][23]. Different variables, such as dental wear, affect PCS, but no connection has been found between caries or missing teeth and PCS [24][25][26]. Occlusal parameters affect PCS, but there is disagreement about the effect of crossbite on PCS [21,[27][28][29]. ...
... Missing teeth on the left side increases both sides chewing, and one reason for that could be that maybe chewing is weighted to the right side among both side chewers. Some of the previous studies have found that missing teeth or implants do not have an impact on PCS [26,35], but others have found that asymmetric tooth loss can lateralise chewing pattern [36]. The present study agrees with that. ...
Objective: The aim of this study was to find out how the preferred chewing side (PCS) affects facial asymmetry , what kind of factors affect PCS and whether there are differences in facial asymmetry between symmetrical and asymmetrical masticators. Material and methods: The study included 748 subjects (females n = 452, males n = 296) born in 1985-1986 in Northern Finland (Northern Finland Birth Cohort 1986, NFBC 1986). Subjects' faces were captured in facial 3D images with stereophotogrammetry technology, and they filled in a questionnaire concerning oral health. A comprehensive dental examination was done by a dentist. Subject's chewing side preference was studied by chewing a piece of paraffin, cotton roll or parafilm. Asymmetry was measured from 3D images with different asymmetry measurements and facial landmarks. Results: Reduced number of teeth on contralateral side affects PCS (odds ratio [OR] = 2.44 in the case of one tooth is missing). Being female increased the whole face and lower face symmetry (p < 0.001-0.824). Self-reported temporomandibular disorders (TMD) pain has an effect on the sidedness of the chin; there is more pain in the larger side of the chin (OR = 9.45). Different chewing materials had no significant effect on the proportion of chewing sides. Conclusions: Females have a more symmetrical face compared to males. PCS does not have a statistically significant effect on facial asymmetry, but the variable affecting PCS itself is extracted teeth. ARTICLE HISTORY
... [9][10][11] Various studies found masticatory laterality as a major peripheral laterality test for estimating the activity of cerebral centers. [12][13][14] Khamnei et al., 2 Nissan et al., 15 Rovira-Lastra et al., 16 Serel Arslan et al., 17 observed relationship of PCS to hemispherical laterality test of eyeness, footedness, handedness and other laterality tests. The awareness on PCS and its testing methods can assist in establish better occlusal contacts and scheme for prosthesis. ...
... 4,14,24,36,37 The method was repeated seven times and preferred side of holding the bolus was recorded. 15 The masticatory laterality was classified as consistent preferred chewing side (CPCS) if the bolus was found on the same side for 7/7 of the chewing cycles. Preferred chewing side (PPCS) was perceived if bolus was found on the same side for 5/7 or 6/7 chewing cycles and observed preferred chewing side (OPCS) was resolved based on maximum chewing side preference. ...
Purpose:
The lateralization can influence the choice of occlusion scheme, patient comfort and success of the prosthesis. The existence of favored masticatory side in complete denture patients and its influence with various occlusal schemes is less analyzed in the literature. The study objective was to compare the masticatory and hemispheric laterality in complete denture subjects rehabilitated with 2 different occlusal schemes at different time intervals.
Methodology:
The cohort study recruited 26 patients in each group of balanced and non-balanced occlusion with definitive criteria. Conventional procedures were followed in denture fabrication. The hemispheric and masticatory laterality for all participants were established at 0,1,3- and 6-month intervals. The laterality was categorized as preferred chewing side (CPCS), predominant preferred chewing side (PPCS) and observed preferred chewing side (OPCS). The data on chewing side preference was analyzed by chi square test. (α = 0.05).
Results:
Right side preference was predominant in 86.1% of non-balanced and 60.1% of balanced occlusion participants. The side preference among the 2 laterality and across time interval decreased in masticatory laterality of balanced occlusion participants (P < .05) when compared to non-balanced occlusion. (P > .05).
Conclusion:
The balanced occlusion dentures had lesser masticatory side preference when compared to non-balanced occlusion complete denture.
... It was found that chewing side preference positively correlates with other hemispherical lateralities, like footedness, eyedness and earedness. Yet it less related to handedness, owing to the more pronounced effect of social learning and peripheral factors (8). ...
... Wilding et al. 1992& Wilding 1993 have shown that PCS is not associated with the size of contact area or chewing efficiency. Moreover, no correlation was found between PCS and missing teeth, occlusion type, lateral guidance and gender (8). Yet, others maintain that chewing side preference is affected by local dental factors. ...
This study aimed at determining whether the individual's chewing side preference is affected by local effects, produced by the presence of implant-supported restorations. The test group included 81 patients with partial implant-supported prosthesis. The control group included 108 subjects with no implants. All subjects went through a series of laterality tests for chewing and tasks (hand, foot, eye and ear) side preference. The preferred chewing side (PCS) was determined by observing the first stroke of the chewing cycle during chewing a gum. A positive and significant correlation between the chewing side preference and the subject's sidedness during the different tasks was examined, by performing four Phi correlation tests for: chewing and handedness(r = 0AE54; P < 0AE001); chewing and footed-ness (r = 0AE49; P < 0AE001); chewing and eyedness (r = 0AE65; P < 0AE001) and chewing and earedness (r = 0AE66, P < 0AE001). Of the subjects, 78AE3% preferred the right side for chewing, 19AE1% preferred the left and 2AE1% had no clear side preference. There was no statistical difference in chewing side preference distribution between genders. The distribution of chewing side preference was not significantly affected by the location of missing teeth or implants. In conclusion, implant placement will not affect PCS. Therefore, information on chewing side preference should be part of the routine preoperative examination for implant-supported restorations to provide a better treatment plan in those cases that the implant-supported restoration will be on the PCS.
... To date, no study has evaluated protrusive and excursive movements in TMD-M patients. J Nissan et al. [23] (2004) suggested that the right side is the preferred side for chewing by the majority of the population. This may lead to continuous loading of the masticatory muscles on the right side. ...
Background: Temporomandibular disorders associated myalgia (TMD-M) is one of the most common patient complaints in clinics. Because of the disease’s multifactorial etiology and complexity,extensive understanding is required to determine an appropriate treatment protocol. Methods: The current randomized comparison study included 80 patients who presented to the outpatient department with a TMD-M complaint. Patients were randomly assigned to one of two groups: continuous therapeutic ultrasound or pulsed therapeutic ultrasound, according to a standard protocol. The key outcome measures were pain intensity (visual analog scale (VAS), 0–10 cm) and muscle pressure pain threshold (PPT). Secondary outcome assessments included changes in maximal mouth opening, functional movements, and depression (Beck Depression Inventory (BDI)). A descriptive analysis was performed on the dataset to get data estimates for all variables. Results: The means of the differences in the two group’s values were compared. Intergroup comparisons for normally distributed data were performed using independent sample t-tests, and intragroup comparisons using repeated-measures Analysis of variance (ANOVA). For non-normally distributed data, such as pressure pain sensitivity (PPT), BDI, left laterotrusive movement (LLT), and protrusive movement (PM), intergroup comparisons were performed using the Mann-Whitney test, and intragroup comparisons using the Friedman test followed by the Wilcoxon signed-rank test. Although the intragroup changes in visual analogue scale (VAS) score, PPT, BDI, LLT and PM were highly significant in both groups (p < 0.001), there was no significant intergroup difference in pain reduction, PPT, BDI, LLT or PM (p > 0.05). There were no significant intergroup or intragroup differences in mouth opening or right lateral movement. Conclusions: Both the pulse and continuous modes of therapeutic ultrasound (US) are equally effective in relieving pain. US therapy in both modes is a potent and independent therapeutic modality for the treatment of TMD-M. Clinical Trial Registration: NCT05211245.
... However, Williams and Ericsson (2005) have stated that such hand preferencebased differentiation is unlikely to reflect true performance in sports (17). While the fact that one hemisphere is heavier than the other is considered an anatomical cerebral lateralization, hand preference is regarded as functional cerebral lateralization (13). ...
The main purpose of this study is to examine the effects of cerebral lateralization on volleyball skills comprehensively. The task distribution between the right and left hemispheres of the brain and the effects of these hemispheres on the individual's motor skills, coordination ability, and reflexes constitute an important research topic in terms of sports performance. A sociodemographic information form, lateralization test and volleyball skill questionnaire were used for the participants. A total of 108 participants were reached. The SPSS package program was used to statistically analyze the data obtained at the end of the research. When the obtained data were examined, it was seen that there was no significant difference in volleyball basic skills scores according to lateralization groups (p>0.05). As a result, it can be said that the dominant hand usage status does not affect volleyball basic skills.
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... The authors present a clinical example of eff ective collaboration between an aesthetic doctor and a dentist in solving dental problems related to hypertrophy of the masseter muscle. Keywords: botulinum toxin type A, abobotulinumtoxin, masseter hypertrophy, bruxism, face _________________________________________________________________________________________________ Гипертрофия жевательной мышцы (ГЖМ) -состояние, проявляющееся увеличением ее объемов, как правило, унилатерально (из-за того, что большинство людей (до 75%) предпочитают жевать на доминирующей стороне) или реже (25-30%) с двух сторон [17][18][19]. ГЖМ чаще всего развивается у лиц молодого возраста (20-40 лет), одинаково часто у мужчин и у женщин [18,20]. У пожилых пациентов возрастные ухудшения в состоянии зубов подавляют способность сильно стискивать их или скрежетать ими [21]. ...
Гипертрофия жевательной мышцы (ГЖМ) клинически проявляется увеличением ее объемов с одной или двух сторон. Нередко она может выступать в качестве основной причины изменения пропорций нижней трети лица, утяжеляя его, приводя к формированию квадратного контура нижней челюсти, что неизбежно отрицательно влияет на эстетическое восприятие индивидуумом самого себя. Дискомфорт, испытываемый пациентом, не единственное последствие ГЖМ, ему обычно сопутствуют медицинские проблемы функционального и органического характера: бруксизм, патология височно-нижнечелюстного сустава, болевой синдром, повышенная стираемость зубов, резорбция костных тканей верхней и нижней челюстей, ускорение процессов старения нижней части лица и др. Точные причины развития ГЖМ до настоящего времени неизвестны. Цель. Оценка эффективности и безопасности использования препаратов на основе ботулотоксина типа А (БТА) в коррекции гипертрофии жевательной мышцы. Материалы и методы. Поиск статей по теме проведен в электронных базах данных MEDLINE, Web of Science, Cochrane Library. Методика лечения ГЖМ препаратами на основе БТА предполагает введение последнего в нижнюю заднюю часть m. masseter. Дозировка и расстановка точек инъецирования могут варьироваться в значительной степени и зависят от выбранного продукта БТА, объема мышцы, пола, возраста, кратности инъецирования и рекомендаций экспертов географического региона, где БТА реализуется. Результаты. Максимальный лечебный эффект от процедуры обычно развивается через 4 недели с момента ее выполнения. Стабильный эффект в виде уменьшения мышечной массы массетера, изменения контуров нижней трети лица, разрешения болевого синдрома, снижения симптоматики скрежетания зубами и их стискивания ожидаем в последующие 6 месяцев и более. Побочные эффекты при соблюдении протокольных правил введения БТА минимальны и кратковременны. Данные исследований, посвященных атрофическим изменениям в мышечной ткани после проведения однократной инъекции БТА у лабораторных животных, не могут быть экстраполированы на человеческую популяцию, поскольку не подтверждены имеющимися исследованиями на людях. Эффективное и относительно безопасное лечение ГМЖ при помощи БТА позволяет рассматривать его как этап в комплексном подходе к решению некоторых стоматологических проблем. Авторы приводят клинический пример эффективного взаимодействия врача-эстетиста и врача-стоматолога в решении проблем стоматологического профиля, связанных с гипертрофией m. masseter.
Hypertrophy of the masseter muscle (HMM) clinically manifests as an increase in its volume on one or both sides. It is often considered the primary cause of changes in the proportions of the lower third of the face, making it heavier and leading to the formation of a square contour of the lower jaw, which inevitably negatively affects an individual’s aesthetic perception of themselves. The discomfort experienced by the patient is not the only consequence of HMM; it is usually accompanied by medical problems of a functional and organic nature: bruxism, temporomandibular joint pathology, pain syndrome, increased tooth wear, resorption of bone tissues of the upper and lower jaws, acceleration of aging processes in the lower part of the face, etc. The exact causes of HMM development are still unknown. Purpose. To evaluate the effectiveness and safety of using type A botulinum toxin (BTX-A) based products in the correction of masseter muscle hypertrophy. Materials and methods. A search for articles on the topic was conducted in the electronic databases MEDLINE, Web of Science, and Cochrane Library. The treatment method for HMM using BTX-A based products involves injecting it into the lower posterior part of the masseter muscle. The dosage and placement of injection points can vary significantly and depend on the chosen BTX-A product, muscle volume, gender, age, frequency of injections, and recommendations from experts in the geographic region where it is implemented. Results. The maximum therapeutic effect of the procedure usually develops within 4 weeks from its completion. A stable effect in the form of a reduction in masseter muscle mass, changes in the contours of the lower third of the face, resolution of pain syndrome, and reduction of symptoms of teeth grinding and clenching is expected in the subsequent 6 months or more. Side effects, when protocol rules for BTX-A administration are followed, are minimal and short-lived. Reports dedicated to atrophic changes in muscle tissue after a single injection of BTX-A in laboratory animals cannot be extrapolated to the human population, as they are not confirmed by existing human studies. Effective and relatively safe treatment of HMM with BTX-A allows it to be considered as a stage in a comprehensive approach to solving some dental problems. The authors present a clinical example of effective collaboration between an aesthetic doctor and a dentist in solving dental problems related to hypertrophy of the masseter muscle.
... Also, as Geschwind and Galaburda stated 17 , males showed a higher degree of brain asymmetry, which could lead also to the facial phenotypic differences between the sexes. At the same time, more than 75% of right-handers prefer the right side for chewing 6 , and in more than 50% there is a match of the chewing side preference with handedness. Stronger unilateral chewing is present when chewing hard food 51 . ...
We aimed to describe facial directional asymmetry (DA) in individuals with different manifestations of laterality. Due to the overlap between brain and face development, a relationship between the manifestation of brain laterality and DA is hypothesised. These findings could clarify the relationship between the brain and facial phenotype and help to plan facial or oral motor rehabilitation. The DA of 163 healthy individuals was assessed by two complementary 3D methods: landmark and polygonal surface analysis using colour-coded maps. Handedness was assessed using the Edinburgh Handedness Inventory, while chewing side and eye preferences were self-reported. The results showed a similar DA pattern regardless of sex and laterality (the right-sided protrusion of the forehead, nose, lips, and chin) and a slightly curved C-shape of the midline in landmark analysis. A relationship between lateralized behaviours and DA was found only in males, in females the DA pattern was more homogenous. Right-handed individuals and right-side chewers showed a protrusion of the right hemiface. Males, left-handed and left-side chewers, manifested a protrusion of the left lateral hemiface. We suggest that these specific differences in males may be due to their typically higher level of brain asymmetry. No apparent relationship was found between eyedness and DA.
... Humans have been documented to display a behavioural pattern towards using one side of the body in relation with the dominant hemisphere of the brain [27,28]. Although the study population were not subjected to hemispherical literalities testings, a slight majority of them had a preferential right side of the mouth (37.79%) over the left side of the mouth (36.79%) for chewing. ...
Introduction: In Nigeria, the incidence of orodental infections and demographics of affected patients are poorly documented. This study aims to evaluate the trends, demographics and comorbidities among patients with oral infections in two study centers in Benin City.
Materials and Methods: This study evaluated five hundred and ninety-eight patients from the outpatient departments in the Dental Clinics of the University of Benin Teaching Hospital and Central Hospital, Benin City, Nigeria. Patient data collected were age, gender, diagnoses, duration of symptoms, preferred chewing side, position of extracted tooth/teeth, and underlying reported health conditions.
Results: A total of 56.86% of our respondents were females. The highest occurrence of oral infections was within the age range of 21-30 years (27.26%). The most encountered diagnoses were periodontitis (55.85%) and caries (19.57%). Retained roots (3.34%) and fractures (6.52%) accounted for non-infectious diagnoses. Comorbid conditions in the population were peptic ulcer, hypertension and/or diabetes mellitus. Time frame for seeking medical care showed that 236 patients reported for care within one week. Other observed time frames were 1-4 weeks (208) and greater than four weeks (154).
Conclusion: Patients between 20-30 years in both sexes were more predisposed to oral diseases with acute apical periodontitis being the most prevalent, followed by dental caries. Peptic ulcer, hypertension and/or diabetes were the coexisting chronic conditions of the study participants.
... Many studies have found transverse asymmetries in the maxilla in both sexes, with unilateral mastication being the most frequent occurrence, resulting in greater expansion [16]. A previous study reported that most patients preferred chewing on the right side (78.3%) and were right-sided [17]. Thus, it can be concluded that masticatory preference may be similar to hand laterality, probably due to the dominant hemisphere of the brain [18], and that asymmetric development in certain brain regions may contribute to the development of asymmetric facial regions [19]. ...
Objectives: To investigate the parameters of pterygomaxillary suture (PMS), including thickness, height, and angulation, using computed tomography (CT) scans to enhance surgical precision and maximize the safety of patients during Le Fort I osteotomy.
Materials and Methods: Computed tomography was performed to analyze both sides of the face in 100 Taiwanese patients (50 males and 50 females) aged 18–50 years. They were recruited randomly from our database and met the inclusion criteria of age, absence of jaw lesions, and no previous facial trauma or surgery. The thickness, height, and angulation of pterygomaxillary sutures (PMS) were assessed.
Results: The PMS thickness was significantly greater in males (7.76 ± 1.7 mm) than in females (6.96 ± 1.46 mm) (P = .0002), but no significant differences were observed between sides or ages. PMS height was greater in females (8.9 ± 2.0 mm) than in males (8.02 ± 2.21 mm) (P = .0011), but no significant differences were observed between sides or ages. The angulation of PMS was significantly greater on the right side (62.84 ± 4.64°) than on the left side (61.19 ± 5.2°) (P = .016), but no significant age- or sex-related differences were observed.
Conclusion: Anatomical variations in PMS regarding height, thickness, and angulation were observed between the sexes. Preoperative computed tomographic evaluation is crucial for ensuring the safety of orthognathic surgery.
Clinical Relevance: This study identified variations in PMS among different groups, which can assist surgeons in achieving better safety and precision in the disarticulation of PMS.
... This is also consistent with studies indicating that subsistence mode affects craniofacial variation (Von Cramon-Taubadel, 2011;Noback & Harvati, 2015). It is also interesting that the right side of the maxilla and zygomatic have the largest morphological changes and that the pooled variance is larger here than on the left side because it is described in the literature that people tend to chew more with the right side (Nissan et al., 2004;Khamnei et al., 2019), which indicates that this method of studying variance manages to discriminate relatively small shape changes. We therefore believe that the major variation in cranial shape in this sample is functionally driven. ...
The study of the shape variation in geometric morphometrics has an important limitation known as the Pinocchio effect. The Pinocchio effect produces artifactual variances of the landmarks and implies that it is not possible to know the morphological change structure of an object, other than by dividing the landmark sets and then comparing them. This, however, involves making prior assumptions about the pattern of variation of an object. In this study, we provide a code in R to iterate over a complete set of landmarks and test all possible combinations of landmarks until deliver those landmarks associated with the largest to the smallest morphological changes. We tested this on a sample of 28 landmarks in 143 3D models of human skulls. The results indicated that this process can result in a pooled variance of a subset of landmarks that is an order of magnitude larger than that of several other regions of the skull. This method makes it possible to describe the pattern of variation of any 2D or 3D object represented by fixed landmarks, to distinguish the shape features that have more morphological dispersion, and to avoid any aprioristic assumptions about how the morphological changes of an object behave.
... Habitual chewing induces laterality in masticatory functions, including occlusal force, occlusal contacting area, tongue movement, and masticatory efficiency [24][25][26]. Habitual chewing side is thought to be controlled centrally [27], but chewing side can be managed consciously as behavior modification therapy and the preferred side can change through improvement in the occlusal condition with orthodontic treatment [28]. However, there are no reports on the relationship between masticatory functions and the stability of orthodontic mini-screws. ...
This study aimed to analyze the relationship between bone density, habitual chewing side (HCS), and mini-screw stability to investigate the intra-individual factors contributing to mini-screw failure. This retrospective study included 86 sides in 43 adults, who underwent bilateral maxillary mini-screw placement with subsequent unilateral failure of the mini-screw. Pre-treatment cone-beam computed tomography was used to measure the buccal cortical bone thickness and bone density on the failed and successful sides. Pre-treatment mandibular kinesiographic records were used to determine the HCS. Paired t-tests, one-proportion z-tests, and multivariable multilevel Poisson regression were used to examine the statistical significance. The buccal cortical bone thicknesses were 0.93 ± 0.27 mm (unsuccessful side) and 1.01 ± 0.27 mm (successful side), with no significant difference. The bone density on the unsuccessful side (1059.64 ± 202.64 mg/cm³) was significantly lower than the success side (1317.89 ± 332.23 mg/cm³). Regarding HCS, 27.9% of failures occurred on the preferred side, and 62.8% occurred on the non-preferred side. After adjusting for all factors, the non-preferred side showed a 2.22 times higher prevalence ratio for mini-screw failure than the preferred side. HCS is significantly related to mini-screw stability, while the cortical bone thickness, bone density, and site of mini-screw implantation were not correlated.
... The unilateral chewing habit, primarily chewing on only 1 side, can be attributed to several factors, such as nervous inconsonance, self-habits, and dental problems. 24 Although heredity is essential for determining mandibular growth and development, environmental factors also play roles. During the early stages, the mandibular development is boosted by mechanical force. ...
... Furthermore, since suppression of vision resulted in both groups in an anterior shift in EO max but not in EO min , this asymmetry appears to be independent of occlusal characteristics. This could be related to a hemispheric predominance, as reported during mastication [40,41]. ...
Conflicting results on the effects of occlusal proprioceptive information on standing sway have been reported in the literature, partly due to the heterogeneity of the occlusal criterion studied and the experimental protocol used. In this study, occlusal functions, different mandibular positions and visual conditions were used to investigate the involvement of occlusal proprioception information in static postural balance. Postural adjustments of 26 healthy young adults, divided into Class I malocclusion and Class I normocclusion groups, were studied in upright position, in five mandibular positions (1 free, 2 centric and 2 eccentric), with and without vision. Due to different reported test durations, postural parameters were examined for the first and last halves of the 51.2 s acquisition time. A permutation ANOVA with 4 factors was used: group, mandibular position, vision, time window.
Mean length of CoP displacement was shorter with vision (ES = 0.30) and more affected by vision loss in the free than in the intercuspal mandibular position (ES = 0.76 vs. 0.39), which has more tooth contacts. The malocclusion group was more affected by vision loss (ES = 0.64). Unexpectedly, with vision, the mean length was smaller in one eccentric occlusion side compared to the other (ES = 0.51), but independent of the left or right side, and more affected by vision loss (ES = 1.04 vs. ES = 0.71). The first-time window of the acquisition time, i.e. 25.6 s, was sufficient to demonstrate the impact of dental occlusion, except for the sway area.
Comparison of the two visual conditions was informative. With vision, the weight of occlusal proprioception was not strictly related to occlusal characteristics (number of teeth in contact; centered or eccentric mandibular position), and it was asymmetrical. Without vision, the lack of difference between groups and mandibular positions suggested a sensory reweighting, probably to limit postural disturbance.
... Functional activities necessitating the coordinated use of hand, foot, eye, and auditory functions exhibit a unilateral preference. This phenomenon is termed laterality (Nissan et al., 2004). Generally, individuals tend to favor one side over the other when employing hands or feet. ...
This study aims to evaluate the risk of traumatic brain injury by comparing data obtained from elite active boxers and healthy individuals through the application of the Symbol Digit Modalities Test and the Trail Making Test, which are sensitive to brain damage, as well as the Verbal and Nonverbal Cancellation Test, which is sensitive to the right parietal lobe. The study is conducted with eight male boxers with an average age of 19.3±2.60 years, who had an average of 7.25±3.41 years of active boxing experience, and ten healthy males with an average age of 19.7±1.05 years, who had no involvement in any combat sport. Participants were administered three Symbol Digit Modalities Tests and two Trail Making Tests, along with the Verbal and Nonverbal Cancellation Test, across intervals of one day of rest. For the analysis, the significance level was accepted as p
... Furthermore, since suppression of vision resulted in both groups in an anterior shift in EO max but not in EO min , this asymmetry appears to be independent of occlusal characteristics. This could be related to a hemispheric predominance, as reported during mastication [40,41]. ...
... Left and right symmetric components; functional activities that require using hands, feet, eyes, and hearing have a single side preference. Single-side-only preference is called laterality (Nissan et al., 2004). People often prefer one over the other in using their hands or feet. ...
This study aims to explore any possible relationships between rhythm sense levels and hand preference, eye dominance, hearing durations, and sports ages of elite amateur boxers who continue their active sports lives. 80 healthy male elite amateur boxers between the ages of 17 and 35 participated in the study. Their rhythm sense levels, hand preferences, eye dominance, and hearing durations were determined. Data were analyzed through the chi-square test for discovering potential connections among the variables. Findings indicate a statistically significant relationship between left-handed and right-handed boxers in terms of rhythm sense levels (χ2 = 14.435, p = 0.002), between rhythm sense levels and sports ages (χ2 = 9.317, p = 0.025) and rhythm sense levels and hearing durations (χ2 = 12.971, p = 0.044). However, no significant relationship was detected between rhythm sense levels and eye dominance (χ2 = 943, p = 0.815). Elite amateur boxers with different hand preferences may differ in their rhythm sense levels and lengthened regular boxing training can improve the level of rhythm sense.
... There is also sidedness in the masticatory function, referred to as the habitual chewing side or preferred chewing side (PCS) [9,10], which is observed in both children and adults [10,11]. PCS is more prevalent on the right than the left side in adults [12][13][14]. There is a relationship between PCS and the sidedness of various organs determined by the brain (e.g., dominant hand, foot, eye, and ear) [1,5], with some reports suggesting a strong relationship with the dominant ear [15,16], while others indicate that there is no association [17]. ...
Whether orthodontic treatment can change the preferred chewing side (PCS) is unknown. This study examined (1) if the PCS changes after orthodontic treatment and (2) which factors contribute to this change. Two hundred fifty patients who visited the orthodontic clinic at Tokyo Medical and Dental University Hospital between 2017 and 2020 were included in the study. Mandibular kinesiograph (MKG) was taken at pre- and post-treatment, and PCS was determined. Patients who showed a change in PCS to the opposite side and those who showed no change in PCS at post-treatment were pooled into the PCS-changed and PCS-unchanged groups, respectively. The demographic, clinical, and cephalometric parameters were compared between the groups. Significant factors associated with changes in were of age < 20 years at the beginning of orthodontic treatment (odds ratio (OR), 2.00), maximum lateral mandibular movement to PCS ≥ 10.0 mm at pre-treatment (OR, 6.51), and change in occlusal canting of ≥1.0° (OR, 2.72). The predicted probability of change in PCS was 13.2%, 36.0%, and 67.5% for no factor, one factor, and two factors associated with PCS change, respectively. Orthodontic treatment may change PCS due to patient age, maximum lateral mandibular movement to PCS, and change in occlusal canting.
... A mastigação é uma importante função do sistema estomatognático controlada pelo sistema nervoso central [10,18,22], estando diretamente relacionada à digestão, pois, quanto maior a degradação mecânica dos alimentos, maior será a ação enzimática sobre eles [12]. O ciclo da mastigação envolve uma sequência precisa de movimentos de abertura e fechamento da mandíbula, proporcionados pela ação coordenada da musculatura mastigatória somada ao movimento dos lábios, bochechas e língua [23]. ...
A ação da musculatura mastigatória caracteriza diferentes padrões mastigatórios que influenciam o desenvolvimento craniofacial. À medida que a mandíbula é submetida a diferentes cargas mecânicas, alterações morfológicas no osso podem ocorrer. Objetivo: Avaliar, por meio de exames de tomografia computadorizada de feixe cônico (TCFC), a estrutura óssea da região posterior do corpo mandibular em indivíduos com diferentes padrões mastigatórios. A hipótese do estudo foi que as assimetrias ósseas mandibulares estão associadas a padrões assimétricos de mastigação. Material e métodos: Selecionaram-se para o estudo 23 indivíduos com idade superior a 18 anos. O padrão mastigatório foi determinado por intermédio do método visual, no qual os indivíduos foram instruídos a mastigar de forma habitual um pedaço de pão francês; 17 indivíduos (73,9%) apresentaram mastigação unilateral preferencial e seis (26,1%) apresentaram mastigação bilateral. Nos exames de TCFC, dez cortes transversais do corpo mandibular foram realizados na distal de cada dente, de canino até segundo molar, onde as dimensões do processo alveolar e a espessura do osso cortical foram medidas. Resultados: Não houve diferença significativa entre os lados preferencial e não preferencial de mastigação de indivíduos com padrão mastigatório unilateral preferencial. Em indivíduos com padrão mastigatório bilateral, ao comparar os lados direito e esquerdo, houve diferença significativa na espessura do processo alveolar no primeiro pré-molar, primeiro molar e segundo molar e na espessura cortical inferior do segundo pré-molar. Conclusão: Não foi possível estabelecer uma relação entre a função mastigatória e a estrutura óssea. Sendo assim, a hipótese de que as assimetrias ósseas mandibulares estão associadas a padrões assimétricos de mastigação não foi confirmada.
... On the basis of this pilot study, and despite its inherent limitations, it might also be of future interest to evaluate the previously preferred chewing side of patients, to enable comparison of this preference with the preferred chewing side in long-term use, in particular, because for the human population and all age groups chewing side preference seems to be normal behavior (Barcellos et al., 2012;Nayak et al., 2016;Nissan et al., 2004). For future planning of RPD, this information might be of benefit for obtaining recommendations for placing additional load-bearing structures (i.e., implants) in the jaws for immediate optimum chewing performance or in patients with a known history of bruxism, to better distribute the generated pathophysiological forces. ...
Objectives:
Removable partial dentures (RPDs) are inserted with the aim to restore masticatory function. There is however inconsistent evidence supporting the alleged improvements, posterior occlusal contacts being one of the decisive factors. We hypothesized that the distribution of abutment teeth in RPDs influences masticatory performance and functional parameters. To evaluate the masticatory performance and functional parameters in patients with a RPD using a single mathematical parameter (tilting index [TI]) for both jaws that predicts biomechanical behavior on the basis of the distribution of abutment teeth.
Materials and methods:
Masticatory performance was measured in patients wearing long-time adapted RPDs using the standardized test food optocal, yielding the mean particle size (X50 ). Mastication on the preferred and nonpreferred chewing sides was analyzed. Total muscle work (TMW) was calculated using bipolar electromyographic recordings of the masseter and anterior temporalis muscle. Functional parameters were subjected to multiple linear regression analysis including X50 as a dependent variable and functional units (FU), the number of teeth, bite forces, and sagittal and frontal components of TI (TI α and TI β) as independent variables.
Results:
When the preferred chewing side was tested, none of the investigated parameters correlated significantly with X50 . In contrast, chewing on the nonpreferred side was correlated significantly with performance for most variables (p < .05). This means that increased dental support improved chewing performance with RPDs under these conditions.
Conclusions:
In well-adapted RPDs, the distribution of abutment teeth as expressed by the tilting index seems to be of subordinate importance for masticatory performance.
... This asymmetry could also possibly reflect a degree of muscular asymmetry [39]. Significant and positive correlations have been shown between masticatory laterality, side differences in maximum bite force, and side differences in occlusal contact area at MIP [31,40]. ...
Objective:
Less than ideal contacts have been reported following aligner therapy, but it is considered a transitory problem, spontaneously resolving with the phenomenon of settling. Methods: Thirty-nine orthodontic patients (14 treated with aligners; 25 with fixed appliances) were evaluated with a digital occlusal analysis system (T-scan™10), assessing Maximum Intercuspation contact simultaneity, symmetry, and relative force distribution at treatment completion and after 3 and 6 months.
Results:
No significant differences in occlusal contact quality were found between groups at treatment completion or follow-up. The center of force moved posteriorly and remained stable after 3 months but was located more anteriorly in females (p = 0.01). One-third of patients (both groups combined) had marked contact force asymmetry even after 6 months' retention. Conclusion: Occlusal contacts were comparable at completion of treatment with aligners or brackets and after 3-6 months of retention. Settling did not improve marked asymmetry in all patients.
... In the present study, although there was an improvement in the left and right posterior regions after 6 months in the modified group, the significant increase in the left posterior region (P = 0.001) could be attributed to the preferential unilateral chewing pattern due to dominance of hemispheric laterality. [39] e increase in occlusal contacts and OcFrs in the current study for a retention period of 6 months was seen with the modified thermoplastic retainer. is was due to the partial coverage of the retainer which led to the substantial improvement in the vertical settling of occlusion. ...
Objectives
The main intent of the study was to evaluate and compare the occlusal bite forces after settling between conventional and modified thermoplastic retainer groups using T-Scan.
Material and Methods
This study comprised a total of 20 patients, who approached the retention phase after completion of fixed orthodontic therapy. After debonding (T0), occlusal analysis using the T-Scan system was done at centric occlusion. Group I (control) – 10 patients received the conventional thermoplastic retainer and Group II (experimental) – 10 patients received the modified thermoplastic retainer. Patients were instructed to wear the retainer continuously for 6 months except while eating and brushing. T-scan analysis after 6 months (T6) was done to evaluate the changes in occlusal bite forces. The obtained data were evaluated using STATA/IC software version 16.1 at a predetermined probability value of 0.05 which was considered significant.
Results
The result obtained from this study was suggestive of significant improvement in bite force levels at centric occlusion in the modified thermoplastic group compared with the conventional group. Comparing the right ( P < 0.17) and left ( P < 0.01) posterior region, there was significant increase on the left side. A significant increase at maximum centric occlusion ( P < 0.01) was seen in the region of the first molars. The anterior region did not show any improvement ( P < 0.62) after 6 months of retention.
Conclusion
Partial coverage of thermoplastic retainer significantly improves the occlusal contacts and force levels. The maximum change was seen in the posterior region and the minimum change in the anterior region at centric occlusion.
... Consequently, it could be indicated that in these subjects the maximum intercuspation position coincides almost with the centric occlusion. According to the AI sign, however, our results suggest also that left side could be the referenced one in no pathological cases, in contrast with other studies [76][77][78] in which right side was found as preferential chewing side. This inconsistency with literature, however, could be explained by the modest size of our sample, in comparison with other clinical studies [ 76 , 77 ]. ...
Background and Objective
The occlusion effect on the craniofacial development is a controversial topic that has attracted the interest of many researchers but that remains unclear, mainly due to the difficulties on measure its mechanical response experimentally. This mechano-morphological relationship of the craniofacial growth is often explained by the periosteal and capsular matrices of the functional matrix hypothesis (FMH); however, its outcomes have not been analytically demonstrated yet. This computational study aims, therefore, to analytically demonstrate the mechano-morphological relationship in the craniofacial development of children with unilateral crossbite (UXB) using the finite element (FE) method.
Methods
The craniofacial complex asymmetry of ten children, five of whom exhibit UXB, was 3D-analysed and compared with the biomechanical response computed from a FE analysis of each patient's occlusion. Due to the complexity of the geometry and the multitude of contacts involved, the inherent limitations of the model were evaluated by comparing computed occlusal patterns with those recorded by an occlusal analysis on 3D printed copies.
Results
Comparison's outcomes proved the reliability of our models with just a deviation error below 6% between both approaches. Out of validation process, computational results showed that the significant elongation of mandibular branch in the contralateral side could be related to the mandibular shift and increase of thickness on the crossed side, and particularly of the posterior region. These morphological changes could be associated with periodontal overpressure (>4.7kPa) and mandibular over deformation (0.002 ε) in that side, in agreement with the periosteal matrix's principles. Furthermore, the maxilla's transversal narrowing and the elevation of the maxillary and zygomatic regions on the crossed side were statistically demonstrated and seem to be related with their respective micro displacements at occlusion, as accounted by their specific capsule matrices. Our results were consistent with those reported clinically and demonstrated analytically the mechano-morphological relationship of children's craniofacial development based on the FMH's functional matrices.
Conclusions
This study is a first step in the understanding of the occlusion's effect on the craniofacial development by computational methods. Our approach could help future engineers, researchers and clinicians to understand better the aetiology of some dental malocclusions and functional disorders improve the diagnosis or even predict the craniofacial development.
... Although not related to occlusal comfort or the appearance of any symptoms, this observed asymmetry, of unknown etiology, illustrated postorthodontic uneven contact force distribution. This asymmetry could re ect the patient's preference for chewing on a particular side, as a type of hemispheric laterality (34). One study showed signi cant and positive correlations existed between masticatory laterality, side differences in bite force, and side differences in occlusal contact area at MIP (35). ...
Objective
Less than ideal contacts have been reported following aligner therapy, which is believed will resolve with settling, despite settling improving occlusal balance has not been scientifically confirmed. The aim of this study was to compare the outcome quality of occlusal contacts in patients treated with fixed appliances or clear aligners.
Methods
39 orthodontic patients (14 treated with aligners; 25 with fixed appliances) were evaluated with a digital occlusal analysis system (T-scan10 ™), assessing Maximum Intercuspation contact simultaneity, symmetry, and relative force distribution. The Occlusion Time, the Right/Left force percentage (%R/L), the Anterior/Posterior contact ratio (RAP), and the anteroposterior Center of Force (COF) locations were recorded at treatment completion, and 3 and 6 months after.
Results
No significant differences in measured occlusal contact quality parameter were found between groups at treatment completion or follow-up (OT, %R, RAP nor COF position). The COF moved posteriorly and remained stable after 3 months, near to the first molar, but was located more anterior in females (p= 0.01). 10 patients finished treatment with marked asymmetry, (%R/L > 50±10%), especially in the fixed appliance group (9/25 =3 6%) versus the aligner group (1/14 = 7%). 1/3 of all patients (both groups combined) after 6 months retention had %R/L imbalances > 50±10%.
Conclusions
Occlusal contacts were comparable at completion of treatment with aligners or brackets and after 3-6 months of retention. Contacts increased in the posterior region with time, but settling did not improve marked asymmetry in all patients.
... DA was high in the sample. There is no obvious explanation but it may be caused by chewing side preference (Martinez-Gomis et al., 2009;Nissan et al., 2004). Some mammal species are known to have side-specific chewing preferences, such as horses (Parés Casanova & Morros, 2014) and goats (Parés Casanova et al., 2018). ...
Background
Developmental instability in archaeological samples can be detected through analysis of skeletal and dental remains. During life, disruptions to biological internal homeostasis that occur during growth and development redirect bodily resources to returning to homeostasis and away from normal processes such as symmetrical development. Because dental enamel does not remodel in life, any deviations from normal development are left behind. Even subtle disturbances to developmental trajectory may be detected in asymmetrical development of traits, specifically a random variation in sides termed fluctuating asymmetry. Human dental fluctuating asymmetry studies are common, but here we investigate the permanent dentition of a non-human primate Papio anubis , for potential fluctuating asymmetry relative to sex, weaning, and reproductive maturity. The sample stems from an outlier population that lives in the wettest and most humid habitat of any studied baboon group.
Methods
The skulls of adult baboons were collected after their natural death in Gashaka Gumti National Park, Nigeria. The permanent dentition of antimeric teeth (paired) were measured for maximum length and breadth using standard methods. The metrics were analyzed to assess the presence of fluctuating asymmetry in adult permanent mandibular and maxillary dentition. Measurement error and other forms of asymmetry (antisymmetry, directional asymmetry) were considered and dental measures expressing true fluctuating asymmetry were used to address three research questions.
Results
Males exhibit greater fluctuating asymmetry than females, suggesting that males experience greater overall instability during the developmental period. While weaning is not more stressful than other life history stages for males and females (using the first molar fluctuating asymmetry index as a proxy compared to other teeth), it is more stressful for females than males. The onset of reproduction is also not more stressful than other life history stages for males and females (using the third molar fluctuating asymmetry index as a proxy compared to other teeth), but it is more stressful for males than females. We explore possible explanations for these findings in the discussion.
... Our results do not argue against an influence of genetics (Dworkin and LeResche, 1992;Diernberger et al., 2008) on TMD nor against the influence of central factors (such as handedness) (Pond et al., 1986;Nissan et al., 2004) on chewing function but suggest that chewing function and consequently TMD may be influenced by dynamic and functional factors. Comparisons of our results with previous findings are difficult because most previous studies did not assess the triad of chewing function, CP angle, and LG angle or were not limited to participants with a complete dentition and normal occlusion who had not undergone occlusal rehabilitation (Hoogmartens et al., 1987;Tay et al., 1989;Kumai, 1993;Pullinger et al., 1993;Diernberger et al., 2008). ...
Introduction:
The etiologies of most chronic temporomandibular joint disordersare unknown. However, an association between habitual chewing on a particular side and chronic temporomandibular joint disorders has been reported. The aim of this study was to investigate the differences between sides (affected vs unaffected) of biodynamic factors (including lateral dental guidance determined by dental anatomy) or condylar path angles (determined by temporomandibular joint morphology) and chewing function (physiological alternate chewing vs single habitual chewing side). The study scope was to investigate possible etiological factors to improve the understanding of temporomandibular joint disorders. The null hypothesis was that no difference would be found between sides that are or are not affected by chronic temporomandibular joint disorders in chewing function or in levels of dental or temporomandibular joint remodeling.
Methods:
This cross-sectional, double-blind study involved 24 adults with substantial, chronic, unilateral symptoms diagnosed as temporomandibular joint disorders. Chewing function, temporomandibular joint remodeling (using axiography) and dental anatomy (lateral guidance angles using kinesiography) were assessed.
Results:
Habitual chewing on one particular side was observed in 17 of 24 participants; significantly more (n = 15) chewed on the affected side than on the unaffected side (P = 0.002 in a two-tailed Fisher's exact test; risk estimate = 4.5; 95% CI 1.326-15.277). The condylar path (CP) angle was steeper on the affected side than on the unaffected side (mean (standard deviation) = 50.52° (9.98°) versus 45.50° (7.98°); P = 0.002 in a two-tailed t-test). The lateral guidance (LG) angles were flatter on the affected side in all 24 participants.
Conclusion:
Our results suggest that habitual chewing on one side may be associated with increasing condylar path, with flattening lateral guidance angles, and also with chronic temporomandibular joint disorder on the habitual chewing side.
... It has been commonly accepted that excessive mastication predominance has a high, potentially traumatic effect on dentition, jaw muscles, and temporomandibular joint. The previous studies suggested that long-term mastication predominance might cause asymmetry of facies [32,33]. Partially edentulous patients might need prosthetic interventions to prevent these disorders and to improve mastication predominance and masticatory performance, according to the suggestions of the present study. ...
Mastication predominance in Kennedy class I (KC I) patients has not been well defined. This study aimed to investigate mastication predominance and masticatory performance in KC I patients, including the significance of remaining posterior teeth and removable partial-denture (RPD) treatment. KC I patients who had differences in the number of posterior teeth between left and right sides (D+) and KC I patients who had no differences (D−) were enrolled. Healthy dentate (HD) subjects were also registered as a positive control. Mastication predominance, defined by mastication predominance index (MPI; range 0–100%) calculated from electromyogram activities during voluntary chewing, and masticatory performance were evaluated at pre- and post-RPD treatment. Pre-MPI in KC I D+ was significantly higher than in HD. RPD treatment could significantly improve MPI and masticatory performance in both KC I groups. However, there were significant differences in masticatory performance between each KC I group and HD, regardless of RPD treatment. It was considered that the mastication predominance in KC I patients was affected by the difference in the number of remaining posterior teeth. RPD treatment could improve mastication predominance and masticatory performance in KC I patients, although the latter was not similar to HD group.
... These results point towards a laterality of tooth wear either caused by a chewing side preference based on masticatory handedness (Nissan et al., 2003) or an asymmetry of the underlying dental, muscular or bony structures including the temporo-mandibular joint (Martinez-Gomis et al., 2009;Mizumori et al., 2003). It remains unclear whether differences in bite fore and occlusal contact area are the cause or the result of such masticatory laterality. ...
Among the different factors thought to affect dental wear, dietary consistency is possibly the least investigated. To understand tooth wear of herbivorous animals consuming different dietary consistencies with different abrasive potential, we fed 14 rabbits (Oryctolagus cuniculus) exclusively with a timothy grassmeal‐based diet in either pelleted or extruded form, or the same diets with an addition of 5% fine sand abrasives (mean size 130 µm). First, we offered the rabbits the pelleted and extruded diets as well as the pelleted control and pelleted abrasive diet in a two‐stage preference experiment. Then, the rabbits received each diet for 2 weeks in a randomised serial feeding experiment, where each animal served as its own control. Tooth measurements for wear, growth and height were achieved using a manual calliper, endoscopic examination and CT scans. The analysis of the diets as fed showed almost identical mean particle size, but the extruded diet had a lower density (volume/mass) and softer consistency compared to the pelleted one and was favoured by most rabbits. The rabbits selected against the diet with sand during the preference experiment, possibly because it caused more tooth wear, especially on the teeth most exposed to wear along the upper tooth row (upper P4 and M1). The maxillary teeth also showed evidence of an increased chewing laterality by the end of the experiment. The extruded diet led to a significantly lower cheek teeth height than the pelleted diet, potentially due to the higher chewing effort needed for a similar dry matter intake. The results suggest that dietary hardness alone is a poor predictor of dental wear. The regrowth of the teeth matched wear consistently.
... Masseter muscle hypertrophy is a condition that manifests itself as enlargement of the masseter muscle and can be unilateral or bilateral. [13] The above correlation is in accordance with the previous study which states that etiology of masseter muscle hypertrophy is associated to many factors, including emotional stress, chronic bruxism, and masseteric hyperactivity. [14] The role of muscles of mastication especially the thickness of masseter and its paramount role in the intensity of generated bite force has already been established. ...
Purpose:
To determine the Maximum voluntary bite force among patients having different personality traits.
Methods:
In total, 323 patients were given the big-five inventory (BFI) questionnaire to fill and allotted to the various personality traits. The patients in the Agreeableness (n = 62) and Neuroticism traits (n = 62) were included in the study. They were categorized into groups as Group 1a - Neuroticism male (41 patients) and Group 1b - Neuroticism Female (21 patients) and Group 2a - Agreeableness male (26 patients) and Group 2b - Agreeableness female (36 patients). Highest value of the maximal voluntary bite force (MVBF) was recorded using FlexiForce sensor (B 201) (Tekscan, USA). The statistical data were analyzed by independent t-test (P < 0.05).
Results:
The mean bite force values for Neuroticism male was 778.66 N, Agreeableness male was 699 N, Neuroticism female was 686.24 N, and for Agreeableness female was 565.47 N. Statistically significant differences in the bite forces between the male and female groups of both the groups with the males showing significantly higher bite force values in both groups was seen. Also, the bite force in Neuroticism male was significantly higher than Agreeableness male and bite force in Neuroticism female was higher than Agreeableness female.
Conclusion:
In this study, the highest bite force was seen in Neuroticism males. Additionally, this study infers that personality has significant influence on the quantum of bite force. Thus, personality assessment of the patient can assist the clinician in planning the appropriate treatment.
... Furthermore, footedness can be a more precise indicator of specific cognitive and motor performance features. In the general population, estimates of left-foot preference are around 20% [5,6]. ...
... This evidence of strong behavioral asymmetry in these fossils raises interesting questions about possible functional specializations of the two halves of the brain in early amniotes. In humans, there is evidence that chewing side preference is associated with hemispheric laterality [25][26][27][28]. Unfortunately there is no research looking quantitatively at chewing side preference in non-human animals, but previously proposed hypotheses of deep evolutionary history of brain lateralization in vertebrates [29,30] support our interpretation that this type of lateralized behavior could be found in these ancient reptiles. ...
Lateralized behaviors have been reported in a variety of extant vertebrates, including birds and reptiles [1, 2, 3] and non-human mammals [4, 5, 6]. However, evidence of lateralized behaviors in extinct vertebrates is rare, primarily because of the difficulty of identifying such behaviors with confidence in fossils. In rare instances, paleontologists can infer asymmetry in predatory or foraging behavior, including predation scars on trilobites [7], directionality of invertebrate traces [8], and even behavioral asymmetry in fossil non-human primates [9, 10]. Because lateralized behaviors have been linked to hemispheric (brain) lateralization in some vertebrates [11, 12, 13, 14, 15], evidence of lateralized behaviors in ancient vertebrates might yield clues about the evolutionary origins of vertebrate brain lateralization. Here, we show the earliest evidence of lateralized behavior in a fossil reptile based on repeatable observations of tooth wear in a large sample of intact jaws. The patterns of dental wear along the tooth rows of nearly one hundred jaws of the small, early Permian (289 million years ago) reptile Captorhinus aguti indicate that it exhibited lateralized behavior, preferring to feed using the right side of the jaw. Discovery of such a feeding behavior in this ancient, terrestrial, and omnivorous animal provides direct evidence of the deep history of directional behavior among amniotes and may indicate an early origin of brain lateralization.
... There has been no clearly described relationship between hand dominance and chewing side preference (Martinez-Gomis et al. 2009). Chewing side preference appears to be centrally selected (Nissan et al. 2004). A metronome was used to manipulate and set slow and fast chewing speeds. ...
Aging is associated with physiological changes which can manifest as age-related slowing of voluntary movements. Dual-task conditions can magnify this slowing process in older adults. The current study describes healthy adult chewing patterns and examined effects of concurrent chewing on performance of simple reaction time (RT), finger tapping, and gait. Chewing rates were measured from electromyographic (EMG) activity from the masseter muscle. Stepping rates were calculated using accelerometers mounted on the lower trunk and leg. Tapping rates were collected using accelerometers secured to a fixed surface. Simple RT was attained from a purposely designed switch. Results demonstrated that older adults walked slower, tapped slower, and had slower reaction times compared to young individuals, however chew rates were similar. This dichotomy became more pronounced when motor tasks were performed at faster speeds, with the exception being chewing. Additionally, chewing altered performance of secondary motor tasks for all individuals. Strong coupling emerged between cyclical actions (i.e., chewing-gait and chewing-tapping), reflecting entrainment between the respective neural oscillators driving the actions. In contrast, RT responses slowed appreciably when chewing was performed concurrently, indicating an interference effect. Taken together, these results illustrate the contrasting effects of chewing on a secondary motor task and highlights bidirectional effects of dual tasking on performance.
Background/Objectives
The aim of this study was to examine if a person's preferred chewing side (PCS) corresponds to his/her hemispheric body laterality (HBL) or is dominated by the dental state.
Methods
After ethical approval, 82 volunteers were recruited. Asymmetry of bite force (ABF) was tested using an occlusal force‐meter (GM‐10) on both sides separately. The occlusal contact area (OCA) was observed using a pressure‐indicating film (GC Fujifilm Prescale). The PCS was evaluated using an asymmetry index (ASI) or a visual analogue scale (VAS). Both tests were repeated. For the HBL, participants underwent four different tests to assess handedness, footedness, earedness and eyedness, respectively. Statistical analysis comprised kappa agreement for HBL tests and their repetition, as well as paired Wilcoxon tests for intraoral parameters.
Results
Hand, eye and ear showed a substantial reproducibility, while foot produced moderate agreement (kappa = 0.58, p < 0.001). No correlation was found between a participant's PCS and HBL, with the exception of EAR with VAS (kappa = 0.29, p = 0.001). There was a significant correlation between ABF and the number of residual teeth (NNT) both for PCS ( p < 0.01; r ² = 0.29) and NPCS ( p < 0.01; r ² = 0.18). There was no significant difference between PCS and NPCS for OCA ( p = 0.13). The results revealed a significantly higher number of residual posterior teeth on the participant's PCS (for VAS p < 0.0001; ASI p < 0.03).
Conclusion
Masticatory laterality does not correspond to body hemispheric laterality. Rather than HBL, the number of residual teeth seems to determine on which side a person prefers to chew.
Niniejszy artykuł przybliża zjawisko powiązania między nożnością a preferencjami dotyczącymi gryzienia oraz żucia. Żucie – jako jedna z funkcji prymarnych – jest bardzo ważną czynnością z perspektywy profilaktyki i terapii logopedycznej. Podczas opracowywania kęsa pokarmowego zęby, mięśnie żujące, mięśnie języka oraz mięśnie otoczenia szpary ust wykonują skomplikowaną pracę i koordynują szereg precyzyjnych ruchów. W taki sposób kształtuje się biomechaniczna baza traktu ustno-twarzowego, na podstawie której budowana jest prawidłowa artykulacja. Żucie – jako czynność fizjologiczna – należy do czynności zlateralizowanych. Taki stan rzeczy może być pierwotnie skorelowany z asymetrią anatomiczną i fizjologiczną mózgu. Badacze związani z naukami medycznymi (stomatologią, ortodoncją, protetyką), neurolingwistyką oraz neuropsychologią poszukują związków pomiędzy wzorcem lateralizacji a preferencjami żucia. Na gruncie logopedycznym wątki te są jednak poruszane bardzo rzadko. Podejrzewa się, że całościowa lateralizacja pozwoli spojrzeć na model żucia w sposób bardziej precyzyjny, zauważyć potencjalne nieprawidłowości wynikające z nawyków związanych z obróbką pokarmu, a w konsekwencji wyciągnąć wnioski istotne w postępowaniu logopedycznym (profilaktycznym i terapeutycznym). Ze względu na obszerność tego zagadnienia w niniejszym artykule została poruszona jedynie kwestia korelacji pomiędzy nożnością a preferowaną stroną żucia.
Dogs are animals with strong bite force. This strong bite mechanism has led to significant changes in the skeletal system such as fossa masseterica. It can be thought that one side is used more than the other side in chewing and is related to the preference of using the same side's hand, eye and foot. In the study, directional asymmetry and fluctuating asymmetry, which occurs as a result of chewing asymmetry, were examined on the first molar teeth and the fossa masseterica in 85 dog mandibles including a wide diversity of morphotypes. The association of high PC1 values for directional asymmetry with a pronounced cranial index, as evident in breeds like Pekingese, Pomeranian and Bulldog, indicates a potential evolutionary or selective breeding trend favouring brachycephaly. On the contrary, guardian breeds like the German shepherd and Bernese mountain dog, which typically require strong jaws for their roles, showcased reduced PC1 values, which might be related to their functional morphology. Similarly, the PCA results for the first molar teeth shape variations also highlighted the influence of cranial shape, with boxer dogs displaying notably higher PC1 values. The fluctuating asymmetrical distributions provided valuable insights into individualistic variations. Interestingly, no specific breed distribution trend was observed for these asymmetries, indicating a more individual-based variation rather than breed-based. It is essential to note that while these results provide valuable insights, further studies are required to understand the underlying causes better. Factors like genetic variations, developmental processes, dietary habits and external environmental factors could play pivotal roles in these observed morphological differences.
Background:
It is not clear to what extent chewing is improved by unilateral oral rehabilitation with implant-supported fixed partial prostheses (ISFPPs).
Aim:
This study aimed to investigate whether patients treated with unilateral ISFPPs in the maxilla use their prostheses during mastication to the same extent as they used their contralateral natural teeth. A further aim was to investigate whether there is a correlation between preferred chewing side and laterality.
Material and methods:
Chewing side preference was assessed in 15 participants treated with unilateral ISFPPs in the maxilla. The first, second, third, fifth, and tenth chewing cycles were assessed, and the test was repeated ten times. All participants also answered a questionnaire about their chewing side preference.
Results:
Most of the participants presented bilateral chewing, but two (13%) chewed only on the ISFPP. There was no statistically significant association between the objectively assessed chewing side and dental status (natural teeth or ISFPPs) during any of the recorded chewing cycles (p >.1). There were statistically significant correlations between both the subjectively reported usually preferred chewing side and the subjective chewing side preference during the test, and the objectively assessed chewing side for the first three chewing cycles (p <.01). No correlation was found between handedness and the objectively assessed chewing side.
Conclusion:
In the present study, most participants chewed bilaterally, and chewing was performed both on the ISFPP and on the natural teeth. No correlation was found between the preferred chewing side, objectively or subjectively determined, and laterality.
The human body is symmetrical, but many of its parts, e.g. hands, legs, eyes and ears have better and greater activity on one side: right or left. It is discussed the asymmetrical activity of the tongue while speaking and chewing. The main hypothesis in this study is dependence of two variables: dependent, which is a preference of side chewing and independent, which is handedness described by Laterality Quotient (LQ). It is proposed that asymmetry of chewing is related to handedness.
Chewing side preference means a tendency to use one side to chew food more frequently than the other. Medical studies show that chewing side preference can result in lateral facial asymmetry, teeth abrasion, temporomandibular disorders, malocclusion, and stomach illness. To continuously detect chewing side preference and quantify its severity in daily life, several wearable sensor-based methods have been proposed in recent years. However, these methods are either intrusive or not fine-grained enough. In this paper, we propose a wearable motion sensor-based chewing side detection method. We observe that chewing activity generates mastication muscle bulge and skull vibration, which can be sensed by motion sensors worn on the mastication muscles. In addition, the muscle bulge and skull vibration of the chewing side are different from those of the non-chewing side. These observations motivate us to deploy motion sensors on the left and right temporalis muscles to detect chewing sides. We propose a heuristic-rules based method to exclude non-chewing data and segment each chew accurately. The relative difference series of the left and right sensors are then calculated to characterize the difference of muscle bulge and skull vibration between the chewing side and the non-chewing side. A two-class classifier is trained using long short-term memory (LSTM), an artificial recurrent neural network, to model the data samples and classify chewing sides. A real-world evaluation dataset of eight food types is collected from eight human subjects. The average detection accuracy reaches 84.8%. The highest detection accuracy for a single subject is up to 97.4%.
Wprowadzenie: Okolica ustno-twarzowa jest przestrzenią wspólną dla różnych czynności prymarnych, takich jak na przykład przyjmowanie pokarmu i czynności sekundarnej – mowy. Podczas mówienia język w tylnej części jest usztywniony, podparty za pomocą podniesienia swych boków i ich kontaktu z częściami twardymi jamy ustnej tej okolicy. Podparcie języka jest cechą biologiczną niezależną od języka mówcy. Ruchy wykonywane podczas mówienia opierają się na ruchach wynikających z czynności prymarnych. Badania opisywane w niniejszym artykule dotyczą żucia, czynności wymagającej skoordynowanej pracy różnych mięśni, która może odbywać obu- lub jednostronnie. Główną hipotezą (H1) w tym badaniu jest zależność dwóch zmiennych: zmiennej zależnej (DV), czyli preferencji strony żucia (PCS) oraz zmiennej niezależnej (IV), czyli preferencji ręki opisywanej przez współczynnik Laterality Quotient (LQ).
Metody: Próba składa się z 230 uczestników w wieku 21–43 lat. Do uchwycenia rozkładu zmiennych wykorzystano statystyki opisowe. Współczynnik korelacji rang Spearmana wskazywał na słabą korelację między preferencją strony żucia oraz preferencją ręki (-0,24), dlatego w kolejnym kroku zastosowano test Chi-kwadrat w celu sprawdzenia związku między zmiennymi. Na koniec oszacowano model regresji, aby ocenić powyższą zależność.
Wyniki i wnioski: Zauważono, że u większości badanych dominuje raczej jednostronny model żucia, przy czym u ponad połowy badanych preferowana strona żucia znajduje się po tej samej stronie co ręka dominująca. Jednocześnie około 1/3 uczestników podczas żucia używa jednakowo obu stron. Analiza, zarówno test Chi-kwadrat, jak i model regresji, potwierdziła, że preferowana strona żucia jest istotnie związana z preferencją ręki.
IntroductionThis article deals with the question of determining the dominant hand using morphometric indicators of the first and second molars. The relevance of the topic is due to the conditions that are characterized by terrorism, local military conflicts, rail and air accidents and the necessity to develop new scientifically based methods for personal identification .Material and methodsThe authors obtained and analyzed 99 plaster diagnostic models of the maxilla and mandible. The generalized asymmetry index of the height of the crown of the tooth HcorRL=Hcor6RL+Hcor7RL2 was developed, which could be used as a diagnostic criterion for determining the dominant hand.ResultsAmong the subjects 79% (78/99) were right-handed, 12% (12/99) left-handed and 9% (9/99) were ambidextrous. When calculating the integral indicators of the absolute size of the teeth—crown modulus (mcor), crown mass (Rbcor) and crown index (Icor)—no statistically significant patterns depending on the dominant hand could be found (p > 0.05). Throughout life, there is a more intensive decrease in the hard tissues of the chewing surface of molars due to abrasion, which leads to a decrease in the height of the tooth crown. This fact determines the development of a generalized index of asymmetry of the height of the crown of the tooth (HcorRL). When measuring the height of the tooth crown (Hcor) of the first and second molars significant differences were found, which were included in the development of the HcorRL. According to these calculations, a value of the HcorRL less than 1 (0.947 ± 0.027) indicates a dominant right hand (right-handedness) and an index value of more than 1 (1.085 ± 0.036) indicates a dominant left hand (left-handedness), with p < 0.0001.Conclusion
The number of left-handed people averages between 5% and 30%, therefore determination of the dominant hand can improve personal identification. In addition, detection of the dominant hand can be important for the reconstruction of events.
Human lateral preferences, such as handedness and footedness, have interested researchers for decades due to their pronounced asymmetries at the population level. While there are good estimates on the prevalence of handedness in the population, there is no large-scale estimation on the prevalence of footedness. Furthermore, the relationship between footedness and handedness still remains elusive. Here, we conducted meta-analyses with four different classification systems for footedness on 145,135 individuals across 164 studies including new data from the ALSPAC cohort. The study aimed to determine a reliable point estimate of footedness, to study the association between footedness and handedness, and to investigate moderating factors influencing footedness. We showed that the prevalence of atypical footedness ranges between 12.10% using the most conservative criterion of left-footedness to 23.7% including all left- and mixed-footers as a single non-right category. As many as 60.1% of left-handers were left-footed whereas only 3.2% of right-handers were left-footed. Males were 4.1% more often non-right-footed compared to females. Individuals with psychiatric and neurodevelopmental disorders exhibited a higher prevalence of non-right-footedness. Furthermore, the presence of mixed-footedness was higher in children compared to adults and left-footedness was increased in athletes compared to the general population. Finally, we showed that footedness is only marginally influenced by cultural and social factors, which play a crucial role in the determination of handedness. Overall, this study provides new and useful reference data for laterality research. Furthermore, the data suggest that footedness is a valuable phenotype for the study of lateral motor biases, its underlying genetics and neurodevelopment.
We are two-sided organisms, bilaterally symmetrical around the vertical axis of our bodies. There is no doubt that the two sides of the human body offer a balanced and harmonious appearance, yet upon closer scrutiny, we find that the apparent symmetry of the human form is a global illusion that arises from our habitual inattention to the many observerable structural inequalities in the body.
A review and evaluation of the literature on mastication has been undertaken. Part Idiscusses the form of the masticatory cycle in the natural and artificial dentitions, including the controversial question of whether tooth contact occurs during function. Part II reviews the literature concerning the speed of movement of the mandible, rate of chewing, and the forces developed in chewing. Part III describes masticatory efficiency and performance, the effect of food on masticatory function, and incorporates a summary of all these three papers.
Using EEG spectral analysis the relationships and differences between 16 brain areas were studied in 16 left-, 16 mixed, and 16 right-preferent subjects chosen with a 7 measure laterality test. The largest overall amplitude difference was observed in the 29 Hz band where the left-preferents show significantly greater amplitude. Dominance was demonstrated to be related to higher amplitude and no clear cut whole-hemisphere dominance was found. The temporal areas showed the clearest representation of dominance in most EEG frequency bands tested (from 0 to 34 Hz in 16 bands 2 Hz wide) with greater amplitude on the left side for the right preferent group and greater amplitude in the right side for the left-preferent group.
Recently, the authors realized that an evaluation of the literature on mastication had never been undertaken, and it is hoped that this review presented in three parts, will be of value, not only to the dental clinician, but to other scientists working in associated fields.
The first paper discusses the form of the masticatory cycle in the natural and artificial dentitions, including the controversial question of whether tooth contact occurs during function.
The second paper reviews the literature concerning the speed of movement of the mandible, rate of chewing, and the forces developed in chewing.
The final paper describes masticatory efficiency and performance, the effect of food on masticatory function, and incorporates a summary of all these three papers.
Preference for a particular chewing side may be influenced by several factors, one of which could be the functional contact area on each side of the dentition. In this study, interocclusal wax records were made for each of the 30 subjects. A digital image of the transilluminated wax record was analysed to group 'grey' values into categories of wax thickness. The total area for tight and intermediate tooth contacts was calculated for both the left- and right-hand sides of each subject. The chewing-side preference was recorded. No correlation was found between the area of occlusal contact on one side and the preference for chewing on that side. Occlusal contact area does not appear to be a determinant of chewing-side preference.
Chewing side preference, either right or left, during the first masticatory cycle was studied in 128 subjects. The 'single bite' test was repeated 10 times for each subject, after which an index of side preference was calculated. This index showed a trimodal distribution, i.e. 32% of the subjects had a significant preference. The proportion of subjects with a significant chewing side preference (45%; p = 8.7 x 10-121) during the first masticatory cycle approached that of earedness and footedness. This pleaded for its acceptance as a new type of lateral preference. This view was further strengthened by the reproducibility of chewing preference during the first chewing cycle.
Foot preference has been given only superficial attention in studies of hemispheric lateralization, although it has potential utility for predicting hemispheric dominance. This paper reports the development of a reliable (alpha = 0.89) 11-item behavioral inventory of foot preference. Since footedness and handedness are only partially related, both must be measured reliably to identify individuals who have a consistent right or left side preference. It has yet to be determined whether footedness or handedness has the stronger relationship to other aspects of cerebral lateralization and whether both measures together predict lateralization better than one of them alone.
Ten subjects performed deliberate right and left-sided chewing of gum, each exercise with a duration of 60 s, followed by maximum voluntary teeth clenching (MVC) until onset of pains in the masseter muscles (pain threshold). Contractile activities of the right and left masseter muscles were assessed by integrated and cumulative surface electromyography (EMG). When the right and left muscles functioned as chewing side muscles only, they generated practically identical levels of chewing force; the same applied when they functioned as non-chewing side muscles only. During identical functions, EMGs suggested identical motor unit recruitment and firing patterns in the two paired muscles; i.e., units producing relatively high tensions for chewing side activity, and other units producing relatively low tensions for non-chewing side activity. During isometric MVC activity, until onset of pains, the right and left muscles generated practically identical levels of bite force, but right and left motor unit activity patterns seemed to differ. Right and left motor units might have fired at different rates or begun to drop out at different times. In the latter case, rapidly before slowly fatigued units. There was a tendency for a low pain threshold with high chewing side activity in both masseter muscles. Motor units producing high levels of tension, but easily fatigued, might have caused early onset of muscle pains. No relationships could be established between preferred chewing side and side of initial muscle pains, nor between MVC activity and side of pain onset and preferred chewing side.
The present study investigated the usefulness of a variety of subject variables that have been proposed as having predictive value for determining cerebral organization for language. To accomplish this, a total of 373 subjects (117 left-handers and 256 right-handers) were given 240 trials of a consonant-vowel dichotic listening task to assess direction and degree of language lateralization. Each subject was also classified on the basis of eight subject variables (handedness, strength of handedness, familial sinistrality, writing hand posture, sex, sighting dominance, preferred footedness, and overall laterality). The results of the study indicated that left hemisphere language processing is very pervasive and that most of the subject variables examined were not very useful predictors of language lateralization. In addition, surprisingly, footedness and not handedness was the single best predictor of cerebral organization for language.
Chewing is influenced by a number of factors, which include jaw and tongue movements, the activity of circumoral muscles, bite force and hard oral surfaces, but it is not clear which of these factors is most crucial to efficiency. The mere presence of surfaces such as the hard palate, or teeth, does not insure that chewing will be efficient. The purpose of this study was to explore the relationship between occlusal contact area, and chewing efficiency and to observe the influence of chewing-side preference on efficiency. These variables were recorded for both left- and right-hand sides, in a sample of 26 normal young adults. Chewing efficiency was estimated by the size of food particles collected after a predetermined number of chewing strokes. The particles were measured using image analysis and the median size calculated. Comparisons were made, firstly within subjects, between the left- and right-hand side, and secondly between subjects. Correlations were found between chewing efficiency and occlusal contact area which were more pronounced within, than between, subjects. It was concluded that while occlusal contact area influenced chewing efficiency within the same individual, it could not account for the differences in chewing efficiency found between individuals. Differences in the movement of the jaw and in the bite force may have a greater influence on chewing efficiency than occlusal contact area.