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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.
... 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).
... This motif is under research worldwide, and there are inconsistencies in the methods and results, relating the chewing laterality to the developmental aspects, as well as age, [13][14][15][16] or dental parameters such as complete denture-wearing, occlusal contact, articular especially temporo-mandibular joint (TMJ) dysfunction, and so on; whether such associations being demonstrated or refused. 12,[17][18][19][20][21][22][23][24][25] Pain was also assessed, however no relation low. Rates of concordance of lateralities in right handed subjects and left handed subjects are shown in Table 2 with regard to general masticatory preference and in Fig. 2 with regard to strong masticatory preference. ...
... 18 But Nissan et al claimed that "chewing side preference correlated with other tested hemispherical literalities". 22 A classic study in 1987 also claimed chewing preference is correlated with other lateral preferences. 27 Serel Arslan et al reported similar results in 2017. ...
... Therefore, determining the preferred chewing side in dentistry could be beneficent in preparation of dental prosthetics or dentures or in regard to the dental examinations. 22,30 For determining the preferred chewing side as a basic dentistry examination and history, dentists initially can question the dominant hand side, together with observing the side of the first chew, which we have suggested earlier; 31 and if they were inconsistent, the latter would be more valid, as a matter of statistical conclusions. ...
Introduction:
Humans manifest a behavioral inclination towards more utility of one side of the body, in relation with the dominant hemisphere of the brain. The current investigation assessed handedness together with chewing preference which have not been evaluated in various food textures before.
Methods:
Nineteen young and healthy volunteers chewed hard (walnut) and soft (cake) foods, during surface electromyography recording from masseter muscles. The side of the first and all chews in the two food types were determined and compared with the side of the dominant hand.
Results:
Results indicated the two lateralities in the same side considerably (60%-70%), implying the solidarity in the control of the dominant hemisphere of the brain. The unilaterality was more prominent in the assessment of all chews in hard food, with higher statistical agreement and correlation.
Conclusion:
Thereupon masticatory preference is found with probable origins in the dominant hemisphere of the brain.
... There are also divergent opinions about the correlation between PCS and other peripheral lateralities such as handedness, footed-studies have discovered the connection between PCS and other lateralities (10,11), whereas other studies have not (6). ...
... Among the Angle class I, 82% has the right PCS in the first chewing cycle (10). The corresponding percent for the class II is 64% and for the class III is 63%. ...
... Our study found out that the PCS was related with handedness, footedness and eyedness, which is in line with previous findings (10). People who were right-handed, -footed and -eyed were more evenly distributed by the PCS. ...
Objectives:
To study, whether there are associations between chewing side preference and other lateralities, whether there is a genetic origin for preferred chewing side (PCS), relations to sex, birth order and orthodontic treatment.
Materials and methods:
The study included 113 twin pairs, 57 pairs monozygotic, 47 pairs same sex dizygotic and 9 pairs of opposite sex. The lateralities of preferred chewing side, footedness and eyedness were assessed by functional tests and handedness was checked by asking.
Results:
Right-handed, -footed and -eyed as separated groups, and true-right sided (combined), were evenly distributed by preferred chewing side. By contrast, left-handed, -footed, -eyed and non-right sided used more left or both sides when chewing. Birth order affected preferred chewing side among monozygotic: the first-born twin was more likely to have the preferred chewing side on the non-right, whereas second-born twins used right side. Gender, zygosity and orthodontic treatment were not statistically significant factors.
Limitations:
Examination of chewing sidedness could have been done in several different ways to provide a definite result. Sample size of opposite sex twins was very small.
Conclusions:
Preferred chewing side generally seemed to follow the side where other lateralities occur; however, monozygotic twins seemed to be more receptive to it. True-right sided were more evenly distributed than non-right sided by the preferred chewing side.
... Thus, rehabilitation specialists can use peripheral organs to facilitate the motor adaptation process. Apart from using the predominances of hand, foot, eye, and ear to determine laterality, chewing side preference (CSP) may be an option to determine hemispheric laterality for professionals who are interested in oral motor functions and swallowing, including dentists, physical therapists, speech language pathologists, and occupational therapists ( Nissan et al. 2004). Chewing is a rhythmic function involving the coordinated action of peripheral organs, sensory input, and the central nervous system ( Jiang et al. 2015). ...
... The factors affecting CSP are not exactly clear ( Minato et al. 2009). There are different opinions about whether CSP is organized centrally or peripherally ( Wilding and Lewin 1994;Nissan et al. 2004;Diernberger et al. 2008;MartinezGomis et al. 2009). Some authors assume that CSP is controlled centrally and dental parameters do not affect the preferred chewing side ( Nissan et al. 2004;Jiang et al. 2015). ...
... There are different opinions about whether CSP is organized centrally or peripherally ( Wilding and Lewin 1994;Nissan et al. 2004;Diernberger et al. 2008;MartinezGomis et al. 2009). Some authors assume that CSP is controlled centrally and dental parameters do not affect the preferred chewing side ( Nissan et al. 2004;Jiang et al. 2015). However, it is also reported that asymmetric tooth loss, partial prosthesis, deciduous and mixed dentition, areas of functional occlusal contacts, head posture, the presence of caries, pain, and food texture are related to CSP ( Pond et al. 1986;Gisel 1988;Wilding et al. 1992;Tay 1994;Mioche et al. 2002;McDonnell et al. 2004;Barcellos et al. 2011). ...
Purpose To investigate if chewing side preference (CSP) can be used as an indicator of hemispheric laterality in healthy adults. Materials and methods Seventy-five individuals were included. The visual analogue scale (VAS) was used to determine CSP and laterality test for preferred peripheral organs. Results Significant correlation between CSP and hand, foot, ear, and eye side preference was found (r = .41, p < .001; r = .34, p = .003; r = .35, p = .03; r = .36, p = .002). Conclusion Besides peripheral organs, the CSP can also be used in determination of hemispheric lateralization.
... [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.
... Examination and registration of preferred side deserve further consideration during routine dental examination and treatment. 41 According to researchers like Farias et al, 32 masticatory performance is not correlated with a defined movement pattern, which prevents establishing differences between uni-and bilateral masticators; however, according to these authors, bilateral chewing promotes better masticatory performance. ...
... 40 El examen y el registro del lado de preferencia ameritan consideración en el examen dental rutinario y en el plan de tratamiento. 41 Según investigadores como Farias y colaboradores, 32 el rendimiento masticatorio no está correlacionado con un patrón de movimiento definido, lo cual hace que no haya diferencia entre masticadores uni y bilaterales; sin embargo, según el autor, la masticación bilateral promueve un rendimiento masticatorio mayor. ...
Objective:
To characterize muscle activity and muscle strength in patients with atypical swallowing (AS; n = 88) and competent lips (CL) or incompetent lips (IL) versus a control group (Ctrl; n = 90)
Methods and materials:
An analytical case-control study was conducted using surface electromyography (sEMG) of the orbicularis oris, mentalis and masseter muscles. Compression forces of the orbicularis oris, right and left masseters muscle (Cfrmm, Cflmm)), tongue tensile strength (Tts) via myoscan analysis and resistance of the orbicularis oris (Roo) via dynamo-metry were determined.
Comparisons were made with the Mann-Whitney U test under a 95% confidence interval.
Results:
The amplitude of the sEMG record of the orbicularis oris muscle, in maximal contraction, was lower (p<0.01) in the atypical swallowing group (596.40 ± 175.83) compared to controls (659.83 ± 203.79). The muscle strength studied in the experimental group was lower (p<0.01) than in controls (CFo: AS: 0.31 ± 0.13; Ctrl: 0.38 ± 0,11; Cfrmm: AS: 0.40 ± 0.08; Ctrl: 0.50 ± 0.11; Cflmm: AS: 0.41 ± 0.08; Ctrl: 0.58 ± 0.59; Tts, AS: 0.52 ± 0.14, Ctrl: 0.65 ± 0.14, and Roo: AS: 2.47 ± 0.61; Ctrl: 2.73 ± 0.60). Patients with incompetent lips had a greater muscle activity of the orbicularis oris in swallowing (AS of IL: 197.01 ± 85.84; AS of CL: 160.54 ± 97.03; Ctrl: 147.18 ± 80.10).
Conclusion:
Patients with atypical swallowing showed differences in the strength of studied muscles and the muscle activity of the orbicular oris muscle compared to controls.
... side preference) may influence mandible morphology and asymmetry (Pirttiniemi and Kantomaa 1992;Pirttiniemi 1998). Research on mastication in humans has shown that there is often a side preference linked to handedness (Nissan et al. 2004;Zamanlu et al. 2012), that muscular activity is asymmetrical McCarroll et al. 1989) and that side preference is linked to side performance (Rovira-Lastra et al. 2014). Despite having mainly symmetrical masticatory muscle activity, murines may also show some small degree of side preference, related to their handedness (Collins 1991;Collins et al. 1993), and this may slightly influence some aspects of asymmetry (i.e. ...
... The a priori relationship between mandible asymmetry and bite force performance appears less straightforward. Studies of the masticatory apparatus, notably in humans, showed that asymmetry is generally the norm (Pirttiniemi and Kantomaa 1992;Pirttiniemi 1998), in response to the lateralization of mastication (Nissan et al. 2004;Zamanlu et al. 2012). In mice, lateralization is known, at least for pawedness (Collins 1991;Collins et al. 1993), but their mastication is generally considered to be symmetrical (Weijs 1975;Weijs and Dantuma 1975). ...
Developmental instability, as measured by fluctuating asymmetry is generally considered to increase with genetic and environmental stresses. Few studies have, however, addressed the role of asymmetry in altering organism performance. Here, we measured bite force performance in three strains of inbred and outbred mice derived from wild ancestors. We quantified size and shape directional, and fluctuating asymmetry, as well as inter-individual variation of their mandibles using geometric morphometrics. We also developed a way to estimate shape antisymmetry, to filter it out of the fluctuating asymmetry component. Contrary to our expectations, we found no significant link between bite force and asymmetry levels. Inbreeding did not produce any clear and significant increase or decrease in neither inter-individual variance, nor fluctuating asymmetry. Furthermore, fluctuating asymmetry levels were unrelated to inter-individual variance levels, although these two types of variation affected the same areas of the mandible. We did not highlight any impact of inbreeding depression on bite force. Fluctuating asymmetry was reduced in the mandible, which we argue may be linked to its functional relevance. We found some significant but very reduced antisymmetry possibly linked to lateralization. This lateralization did not relate to any bite force difference. Our results show that neither inbreeding, nor asymmetry (combining fluctuating, directional asymmetry and antisymmetry) significantly affect bite force performance in mice, and that despite affecting the same morphological regions, developmental stability and canalization are independent.
... Right and left symmetrical compound functional activities which require usages of hand, foot, eye, hearing and chew have one lateral preference which is called as laterality paralysis. Hemispheric laterality paralysis is diagnosed with partialities such as handedness, footedness, sightedness and earedness (Nissan et al. 2004). Polemikos and Papaeliou, who made a research on the consistency of preference of foot, eye and ear at the same side of individuals having right hand and lacking right hand by using Lateral Preference Inventory of Coren, state that in spite of domination of right-side is observed in handedness, footedness, sightedness and earedness, lateral preference is not equal in these (Polemikos and Papaeliou 2000). ...
... Footedness is less affected by social pressures and thus it can be a better indicator of hemispheric specialization than handedness. Furthermore, footedness can be a more precise indicator of specific cognitive and motor performance features (Nissan et al. 2004). ...
Our study is made on 39 sportswomen, who attended to The Intercollegiate Women Turkey Football
Championship, aiming at determining and examining the relation of the preference of hand, foot, eye and ear
that give key hints about the functional asymmetry of the brain. In determining the preferences devoted to
laterality, the preference of hand range is fixed with the Oldfield questionnaire and evaluated with regard to the
Geschwind score. Some questions are asked to the subjects in the questionnaires in order to evaluate the
range of preferences about foot, eye, and ear. The questionnaires consist of 4 questions while determining the
foot preference range, 5 questions about the preference of the eye while the activity can be done with one of
them and again 5 questions about the ear while the activity can be done with one of them. The data derived is
saved on SPSS for Windows 16.0 program, the descriptive data is shown with arithmetic average – standard
deviation and percentages, in evaluating the relation between the preferences the correlation analysis is used
and the results are evaluated in 95% confidence interval. As a result, in our study, it is determined that the
woman soccer’s are predominantly right-handed in their all preferences and they dominantly use the left
hemisphere. Although, the results of the study show parallelism with the literature, it can be said that some
differing values can show branch differences in sportswoman groups.
Key words: Cerebral Laterality, Women’s Soccer, Hand and Foot Preference, Eye and Ear Preference
... 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.
... However, the effects of jaw movement in muscle activity in individuals with TMJD remain unclear. Also, mastication has been well-known to occur either unilateral or bilateral, and there is a preference for chewing side (19,20) once chewing has intrinsic characteristics. ...
Background: The effects of jaw movement pattern on masticatory activity during chewing remains unclear in chronic temporomandibular joint disorders individuals. Objective: to assess the effect of habitual and non-habitual mastication patterns based upon the activation of the masseter and temporalis muscles in individuals with or without temporomandibular joint disorder (TMJD). Methods: Fifty-four participants (age: 18–44 years) were divided into two groups: the TMJD (n=27) and control (n=27) groups. TMJD was identified using the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD). Electromyographic activity of the masticatory muscles was measured during 2 tasks: habitual mastication with parafilm (HM) and non-habitual mastication with parafilm (NHM). MATLAB software was used to process electromyography (EMG) signals. The root mean square, symmetry index (SI%), anteroposterior coefficient (APC%) and torque
coefficient (TC%) were determined from the processed EMG signal. Results: Reduced right masseter activation was observed for the TMJD group (p<0.05) during jaw agonist phase. During the jaw agonist phase, all muscles presented with more activation during NHM. Symmetry of temporalis (ST%) and APC% were the lowest for HM. TC% was increased for HM. Conclusion: Habitual and non-habitual mastication differ in masticatory activity during jaw agonist and antagonist phase and TMJD individuals presented a different way to recruit muscles under these circumstances. Non-habitual mastication has a more coordinating and stable motor pattern in masticatory activity and has less variability than habitual mastication to assess masticatory activity.
... However, the effects of jaw movement in muscle activity in individuals with TMJD remain unclear. Also, mastication has been well-known to occur either unilateral or bilateral, and there is a preference for chewing side (19,20) once chewing has intrinsic characteristics. ...
Background: The effects of jaw movement pattern on masticatory activity during chewing remains unclear in chronic temporomandibular joint disorders individuals. Objective: to assess the effect of habitual and non-habitual mastication patterns based upon the activation of the masseter and temporalis muscles in individuals with or without temporomandibular joint disorder (TMJD). Methods: Fifty-four participants (age: 18–44 years) were divided into two groups: the TMJD (n=27) and control (n=27) groups. TMJD was identified using the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD). Electromyographic activity of the masticatory muscles was measured during 2 tasks: habitual mastication with parafilm (HM) and non-habitual mastication with parafilm (NHM). MATLAB software was used to process electromyography (EMG) signals. The root mean square, symmetry index (SI%), anteroposterior coefficient (APC%) and torque
coefficient (TC%) were determined from the processed EMG signal. Results: Reduced right masseter activation was observed for the TMJD group (p<0.05) during jaw agonist phase. During the jaw agonist phase, all muscles presented with more activation during NHM. Symmetry of temporalis (ST%) and APC% were the lowest for HM. TC% was increased for HM. Conclusion: Habitual and non-habitual mastication differ in masticatory activity during jaw agonist and antagonist phase and TMJD individuals presented a different way to recruit muscles under these circumstances. Non-habitual mastication has a more coordinating and stable motor pattern in masticatory activity and has less variability than habitual mastication to assess masticatory activity.
... For addressing these issues, the cortical tongue representation in left-handers, as well as the motor tongue dominance in subjects with right-sided language dominance needs to be examined. Nevertheless, indirect conclusions concerning the relationship between handedness and tongue dominance can be drawn from studies on chewing side preference (Nissan et al., 2004). A relatively close relation between chewing side preference and handedness was found without any influence of peripheral dentine factors. ...
... 1,2 Dental literature is contradictory regarding determinants of PCS. Nissan et al. 3 reported that laterality in the body is determined by cerebral hemisphere; Pond et al. 4 also reported an insignificant correlation between PCS and occlusal factors. Jiang et al. 5 reported that hemispheric dominance in the primary sensorimotor cortex contributed to rhythmic chewing movement. ...
Objectives:
Evaluation of dynamic occlusal parameters can help dentists to understand the association of occlusion with the preferred chewing side (PCS) and enable optimal restoration of masticatory efficiency. This study evaluated the association between PCS and dynamic occlusal parameters.
Methods:
One hundred participants (50 each, right and left PCS) were included in this study. PCS was determined by the visual spot-checking method, and occlusal analysis was conducted by T Scan. Occlusal parameters evaluated included initial contact, center of force, tooth contact area, occlusal interferences, and occlusal time. Data were assessed by chi-squared test and eta correlation coefficient.
Results:
Initial contact towards the PCS was observed in 68% and 70% of right and left unilateral chewers, respectively. Likewise, center of force towards the PCS was present in 72% and 66% of right and left unilateral chewers, respectively. A larger area of tooth contact was predominant towards the PCS in 70% and 72% of right and left unilateral chewers, respectively. Chi-squared analysis showed a strong positive correlation between PCS and occlusal parameters at maximum intercuspation. Eta correlation coefficients between PCS and occlusal interferences, as well as centric and eccentric occlusion, revealed negligible associations.
Conclusion:
Dynamic occlusal parameters may be associated with PCS.
... Clinical investigations have established a right-sided chewing predominance in various subpopulations, 34,35 while other studies have demonstrated a left-sided preference or bilaterality. 36 The present patient had been a habitual right-sided chewer, and the SOH was located on her left side. None of the previous case reports had included chewing-side preference. ...
... However, this bilateral pattern of distribution of food is not present in most of the population, where a preferred chewing side is more common 7,8 . The choice for a preferred chewing side is a voluntary decision that beco- mes involuntary with function performance 9 and may be associated with the control of the central nervous system 10 or related to peripheral factors 9 . ...
Aim: The aim of this study was to evaluate, through cone beam computed tomography (CBCT), the transverse dimension of the alveolar bone in the posterior region of the maxilla and mandible in subjects with different patterns of mastication, comparing both sides of the arches according to the performance of the masticatory function. Methods: 39 subjects not orthodontically treated, with normal occlusion or symmetrical malocclusion, and normal periodontal condition were selected. Twenty-one subjects (54%) were identified as having preferential unilateral mastication, 11 subjects (28%) had bilateral mastication and 7 (18%) had exclusive unilateral mastication. All participants were submitted to CBCT and the buccolingual dimension of the posterior regions was evaluated at a height of 2, 4, 6, 8, and 10mm from the alveolar crest. Results and Conclusion: Subjects with bilateral mastication showed statistically significant difference between the right and left sides at the heights of 6 (p=0.030) and 8mm (p=0.023) between the first and second maxillary premolars. There was no difference in the transverse dimension of the alveolar bone in the posterior regions of maxilla and mandible between preferred and non-preferred sides in subjects with preferred unilateral mastication and between right and left sides in subjects with bilateral mastication.
... 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]. ...
The purpose of this study is to compare technical skills of youth soccer players according to foot preference. A total of 61 amateur football players (Under 15) participated in the study from different clubs of Istanbul. The descriptive statistics and the relationship between the technical skills were examined by using Spearman test and Mann Whitney U test was used for paired comparison of the groups. The level of significance taken into account was (p<0.05). In conclusion, although there were not statistically significant difference between the left-and right footed players in technical skill tests (p˃0.05), and a negative significant relationship was found between dribbling and juggling and long passing skill tests (p˂0.05) in right-footed players. The present study may contribute to the literature on the specific skills related performance profile of youth football players.
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.
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.
Background:
Masseter muscle hypertrophy manifests itself as enlargement of the masseter muscle. It can be associated with a square-angled lower face, pain, dental attrition, maxillary and mandibular bone resorption, and accelerated aging process of the lower face. The objective of this study was to assess the efficacy and safety of botulinum toxin type A in contouring the masseter and its impact on quality of life and the aging process of the lower face, and its role in full face rejuvenation.
Methods:
A PubMed search was conducted for articles on masseter treatment with botulinum toxin type A, masseter muscle hypertrophy, and the aging process of the lower face. Key studies are reviewed and findings are summarized.
Results:
Botulinum toxin type A can be injected into the lower posterior aspect of the masseter muscle. Treatment decreases muscle bulk and reshapes the lower face. Furthermore, patient quality-of-life measures, including pain and symptoms of grinding and clenching, are improved. Treatment can decrease shear stress on maxillary and mandibular bones and can possibly prevent tooth loss and progressive bone resorption of the lower face. Adverse effects are minimal and short lasting.
Conclusions:
Botulinum toxin type A is a safe and effective treatment of masseter hypertrophy. The treatment results in improvement of functionality and cosmesis, and restoration of facial harmony.
INTRODUCTION: the objective was to measure the concordance of three methods to determine chewing side preference in children with cleft palate. METHODS: the sample included 47 children with cleft palate and similar age and socioeconomic level. Methods: the test of Christensen & Radue (1985), the test of Paphangkorakit et al (2006) and surface electromyography (sEMG) were used. Comparisons among groups were made by non-parametric methods. RESULTS: the method of Paphangkorakit et al (2006) did not show concordance with the preference measured by the Christensen & Radue method (1985) (Pearson's X2 = 0.96, p = 0,619; Kappa = ?0.08, p = 0,475). The results showed that cleft type is not associated to chewing side preference measured by the method of Paphangkorakit et al (2006) (Pearson's ?2 = 5.07; p = 0,281; Kappa = 0.07, p = 0,274) but by the method of Christensen & Radue (1985) (Pearson's ?2 = 7.09; p = 0.029; weak Cramer's V association = 0.39, p = 0.029; Kappa = 0.19, p = 0.009). Patients with right cleft palate differ from patients with bilateral cleft in terms of sEMG amplitude asymmetry while chewing (right: 7.3 ± 12.8; bilateral: ?2.67 ± 6.61; U = 104; p = 0,038). CONCLUSIONS: no concordance was found between the two studied clinical methods to identify masticatory preference, nor between these and sEMG.
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.