Article

Manifestation of preferred chewing side for hard food on TMJ disc displacement side

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Abstract

The purpose of this study was to reveal the relationship between chewing-side preference and anterior disc displacement (ADD) of the TMJ. Thirty-two healthy subjects with ages ranging from 26 to 34 years were selected from volunteer students at the Okayama University Dental School. Subjects were asked to chew freely with two kinds of test foods, beef jerky (hard food) and chiffon cake (soft food), thus expecting different amounts of mechanical loading on the TMJ. One, 4, and 7 s after starting the mastication, subjects were asked to open their mouth momentarily to have a digital image of their mouth taken. The bolus placement area was measured by processing the digital images, calculated as the number of pixel of bolus area. Area asymmetry index was used for the determination of preferred chewing side (PCS). Oblique sagittal MRI scanning in the closed mouth position was taken to evaluate the articular disc position. In asymptomatic subjects with ADD, a significant predominance of the PCS on the ipsilateral side of ADD was observed during the mastication of hard food. On the contrary, no correlation was found between unilateral ADD and PCS for the soft food. From the results of this study, it is suggested that ADD is the associating factor of PCS for hard food. Therefore, it would be necessary to break down the concept of PCS into at least two categories, one for hard food and one for soft food, considering the mechanical loading on the TMJ.

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... It has been shown that even healthy individuals chew more on either the left or right side of the dental arch [1][2][3][4][5][6]. Mastication predominance is defined as the habit of chewing predominantly on one side and has been reported to be the cause of temporomandibular disorders, temporomandibular joint disc displacement, and asymmetrical loss of teeth [4][5][6][7][8][9][10]. ...
... Mastication predominance refers to the preferred chewing side [1][2][3][4][5][6]. Our previous studies confirmed validity of MPI to assess mastication predominance and evaluated mastication predominance in healthy dentate subjects, partially edentulous patients and Ken- ...
... Mastication predominance refers to the preferred chewing side [1][2][3][4][5][6]. Our previous studies confirmed validity of MPI to assess mastication predominance and evaluated mastication predominance in healthy dentate subjects, partially edentulous patients and Kennedy class II (KC II) patients [16,17,21,26]. ...
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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.
... The absolute value of the median of the AI (|AI|) shows the extent of masticatory laterality. In this study, a 30% threshold was set for determination of PCS (20,21). Left, right or no PCS was recorded when AI was higher than 30%, lower than À30% or between À30% and 30%, respectively. ...
... Masticatory laterality is affected by the texture of food, and this is more pronounced with harder foods (20,21). Although chewing gum has often been used as a test food for the determination of PCS (32)(33)(34), to accentuate PCS and to reproduce natural chewing, hard, swallowable gummy jellies were used in this study. ...
... Furthermore, the prevalence of PCS was higher among patients with posterior scissors-bite than in subjects with normal occlusion (80% vs. 50%, respectively). In previous studies (21,32,35), the reported prevalence ranged ...
... ratnasari et al (2) 2011 Bolus placement position during mastication was recorded by a digital camera. One, 4, and 7seconds after starting the mastication, subjects were asked to open their mouth momentarily to have a digital image of their mouth taken. ...
... Our data were analyzed as regards, the prevalence of PCS, the relationship between the PCS and TMJ variables including subjective and objective measures, in addition to mandibular and occlusal variables that include; mandibular deviation, limited mouth opening, lateral and protrusive functional ranges, slide in centric, type of occlusion in regards to canine guidance or group function , area of contacting teeth in centric and number of teeth contacts in balancing side relations. All data were demonstrated in table (2). ...
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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.
... Using both sides of the jaw when chewing is an ideal mastication process because it enables alternate active and rest periods of muscle and joint use, which balances the function of mastication and muscle use. Consistent chewing or one-sided dominant chewing is known as a chewing side preference [4,5]. Unilateral chewing preference is common in global populations, with a prevalence of 45-97% [6]. ...
... Unilateral chewing preference is common in global populations, with a prevalence of 45-97% [6]. Unilateral chewing habits may lead to an imbalanced dentofacial growth stimulation and the structural instability of the stomatognathic system [1,4]. ...
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This study was performed to analyze the relationship between the chewing preference and condylar asymmetry in patients with temporomandibular disorder (TMD). A cross-sectional study was performed at Prosthodontic Clinic, Faculty of Dentistry, Universitas Indonesia using secondary data obtained from the medical records of 40 patients with TMD. Panoramic radiography tracing was performed for all patients included in the studyto evaluate condylar asymmetry using the Habets Asymmetry Index and the Kjellberg Symmetry Index. Measurements of condylar asymmetry were then correlated to the chewing preference, Helkimo's Index, and DC/TMD. The data showed no correlation between the chewing preference and condylar asymmetry in patients with TMD.
... Despite the previous findings and the near consensus about association between unilateral chewing preference and TMD (Casanova-Rosado et al., 2006;Ferreira et al., 2014;Ratnasari et al., 2011;Santana-Mora et al., 2009) the relationship between the masticatory muscles in chronic TMD exhibiting different grades of severity is not trivial. Therefore, researchers have investigated the relationship between orofacial motor function and pain by means of EMG analysis, in standardized settings, without the interference of confounding factors. ...
... These results, taken together, add information about masticatory function in patients with chronic TMD. Even with the confirmation, in the current study, of habitual sidepreference during natural chewing (Casanova-Rosado et al., 2006;Ferreira et al., 2014;Ratnasari et al., 2011;Santana-Mora et al., 2009) by clinical examination, all patients were able to perform the task on right and left sides with quite the same energy expenditure. However, independently of side imposed for mastication and chewing preference, they recruited the balancing side more than the control group, specifically the masseter muscle, whose contribution increased as TMD symptomatology worsened. ...
Article
Objective: To investigate whether reorganization of muscle activity occurs in patients with chronic temporomandibular disorders (TMD) and, if so, how it is affected by symptomatology severity. Methods: Surface electromyography (sEMG) of masticatory muscles was made in 30 chronic TMD patients, diagnosed with disc displacement with reduction (DDR) and pain. Two 15-patient subgroups, with moderate (TMDmo) and severe (TMDse) signs and symptoms, were compared with a control group of 15 healthy subjects matched by age. The experimental tasks were: a 5s inter-arch maximum voluntary clench (MVC); right and left 15s unilateral gum chewing tests. Standardized sEMG indices characterizing masseter and temporalis muscles activity were calculated, and a comprehensive functional index (FI) was introduced to quantitatively summarize subjects' overall performance. Mastication was also clinically evaluated. Results: During MVC, TMDse patients had a significantly larger asymmetry of temporalis muscles contraction. Both TMD groups showed reduced coordination between masseter and temporalis muscles' maximal contraction, and their muscular activity distribution shifted significantly from masseter to temporalis muscles. During chewing, TMDse patients recruited the balancing side muscles proportionally more than controls, specifically the masseter muscle. When comparing right and left side chewing, the muscles' recruitment pattern resulted less symmetric in TMD patients, especially in TMDse. Overall, the functional index of both TMDmo and TMDse patients was significantly lower than that obtained by controls. Conclusions: Chronic TMD patients, specifically those with severe symptomatology, showed a reorganized activity, mainly resulting in worse functional performances.
... Temporomandibular disorder (TMD) has multiple clinical manifestations involving dysfunctions and pain in the masticatory muscles, temporomandibular joints (TMJs), and associated structures, and affects a considerable number of adults (Bakke and Hansdottir, 2008;Ratnasari et al., 2011;Schmid-Schwap et al., 2013). Despite several studies, no specific therapies have been proven to be more effective than others to promote pain relief and functional improvement (Michelotti et al., 2012). ...
... The TMD group had significantly lower OMES scores (De Felício et al., 2012a,b) and masticatory function clinically characterized by the perception of greater difficulty to chew, i.e., less ability, prevalence of the unilateral chewing type (Ratnasari et al., 2011) and more time spent during free mastication compared to the Control group. ...
Article
Because temporomandibular disorders (TMDs) rehabilitation continues to be a challenge, a more comprehensive picture of the orofacial functions in patients with chronic pain is required. This study assessed the orofacial functions, including surface electromyography (EMG) of dynamic rhythmic activities, in patients with moderate-severe signs and symptoms of chronic TMD. It was hypothesized that orofacial motor control differs between patients with moderate-severe chronic TMD and healthy subjects. Seventy-six subjects (46 with TMD and 30 control) answered questionnaires of severity of TMD and chewing difficulties. Orofacial functions and EMG during chewing were assessed. Standardized EMG indices were obtained by quantitative analysis of the differential EMG signals of the paired masseter and temporal muscles, and used to describe muscular action during chewing. TMD patients showed significant greater difficulty in chewing; worse orofacial scores; longer time for free mastication; a less accurate recruitment of the muscles on the working and balancing sides, reduced symmetrical mastication index (SMI) and increased standardized activity during EMG test than healthy subjects. SMI, TMD severity and orofacial myofunctional scores were correlated (P<0.01). Impaired orofacial functions and increased activity of the muscles of balancing sides during unilateral chewing characterized the altered orofacial motor control in patients with moderate-severe chronic TMD. Implications for rehabilitation are discussed.
... Concomitantemente, uma contração dos músculos periorbiculares e do músculo mentual também pode ser observada, denotando esforço na realização da função (2,3) . A mastigação é igualmente influenciada pela dor, uma vez que é comumente observada a adoção de um padrão unilateral crônico em casos de DTM (6,7) . Considerando as implicações da desordem no desempenho miofuncional orofacial, o presente estudo se propôs a avaliar a mastigação e deglutição em mulheres jovens com e sem DTM. ...
... No momento da mastigação, os indivíduos com DTM apresentaram mais frequentemente o padrão unilateral crônico, como previamente relatado em outros estudos (3,6,7) , sendo referido como um padrão atípico (3) . ...
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To evaluate chewing and swallowing functions in women with and without temporomandibular disorder (TMD) and investigate the position of the mandible and the hyoid bone as they are important structures in the development of these functions. Seventy women were evaluated in relation to TMD diagnosis according to the Research Diagnostic Criteria, among them, 34 composed the study group (SG) with TMD and 36 took part in the control group (CG). Evaluation of the masticatory and swallowing functions was performed according to the Protocol of Orofacial Myofunctional Evaluation with Scores. Mandibular and hyoid bone position variables were measured by cephalometric analysis. TMD subjects showed a significant difference on tongue (p=0.03) and lip (p=0.04) posture during swallowing function, and a more frequent adoption of a chronic unilateral chewing pattern as well (p=0.03). Moreover, they presented a lower position of the hyoid bone in relation to the mandible (p=0,00). Conclusion: TMD presence resulted on a higher frequency of myofunctional alterations during masticatory and swallowing functions. A greater distance from hyoid bone to the mandible in addition with the presence of painful symptom can justify, partly, the atypical behaviors of the tongue and lips observed on TMD group. The TMD repercussion on alimentaires functions in a young age group justifies the importance of an earlier diagnosis and therapeutic intervention in these individuals.
... For the majority of human physical activity there exists a preference in the use of one side of the body, be it with the hands, feet or eyes [1] . Mastication is not different, and there seems to be a preferred chewing side (PCS) for many individuals as previously reported [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] . The PCS, also called chewing side preference, is the side of the dentition where most of the chewing takes place during mastication [2] . ...
... Conclusion: In this study, we found that unilateral chewing creates uneven wear on the anterior teeth and changed the anterior guidance angulation. Different methods have been used to determine the PCS: visual observation after 1, 3, 5 or 7 consecutive chewing cycles [14] , kinesiography [15] , questionnaire on chewing habits [16] , measurement of bite force [17] , masticatory performance [18] and anterior disc displacement [19] . ...
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Objectives: The aim of this study was to evaluate a possible relationship between preferred chewing side (PCS) and the anterior guidance angle. Subjects and methods: Forty dental nurses and technicians, aged 24-46 years, were each given a piece of chewing gum, which they chewed for about 3 min. At 7 regular intervals (every 15 s), they were interrupted by the principal investigator (P.L.) in order to observe on which side of their mouths they had the bolus of chewing gum. Moulds of their jaws were made and the position of the maxillary arch relative to temporomandibular joints was recorded with a facebow and transferred to a semi-adjustable articulator. After mounting the stone casts of each subject, a measure of the anterior guidance angle was taken with an adjustable incisal table. Results: Of the 40 subjects, 14 (35%) presented a PCS. Among the 14 subjects who preferred a chewing side, there was a correlation between the PCS and a low angulation of teeth constituting the anterior guidance on that side, but this correlation was statistically nonsignificant. Conclusion: In this study, we found that unilateral chewing creates uneven wear on the anterior teeth and changed the anterior guidance angulation.
... Studies have suggested that anterior disc derangement can be associated with chewing hard food. 25 This study has confirmed a significant association of stress/anxiety to TMDs in accordance to other studies. 6,26 Emotional stress has an influence on muscular activity and occlusion. ...
Article
Background: Temporomandibular disorders (TMDs) comprise of a variety of clinical signs and symptoms such as joint sounds, muscle tenderness, joint tenderness, deviation, deflection, pain on mouth opening, protrusive, lateral movement and limited mouth opening which can be the result of trauma, stress, gum chewing, hard food biting habits, bruxism, long dental appointment. This study was aimed to determine the prevalence of temporomandibular disorders in Nepalese population in Eastern Nepal. Methods: The study was performed from May 2018 to Oct 2018. All the patients who came to the Department of Oral Medicine and Radiology, Nobel Medical College and Teaching Hospital (NMCTH) and health camps in Eastern part of Nepal were included. The self-administered questions were asked to the subjects about demographic data, different signs and symptoms of TMDs and etiological factors responsible to it. Results: More than two thirds of the study sample (83.96%) in the present study had one or more clinical signs and symptoms of TMDs. Deviation of mandible on mouth opening and clicking sound made up the highest percentage. Females were reported to have significantly higher prevalence of TMDs signs and symptoms than male. Disc displacement was the most prevalent disorder followed by myofascial pain and degenerative joint disorder. Conclusion: The results of this study show that a significant percentage of the population has signs and symptoms of TMDs. Measures should be taken to prevent and treat TMDs in this part of the world.
... The side that showed greater muscle activity (TMW) was determined to be the preferred chewing side. Similar methods were applied by Yamasaki et al. (2016) and Ratnasari et al. (2011). Second, observation by an examiner was used as an indicator. ...
Article
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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.
... Therefore, the disc has a greater chance of being captured during mouth movement, predisposing individuals to disc displacement [1,26,30]. In this regard, our findings support previous research that showed a positive relation between CSP and internal derangement of TMJ [33][34][35]. ...
Article
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Background Chewing side preference (CSP) has been proposed as one etiology of temporomandibular disorders (TMDs) as it can induce the structural changes of the temporomandibular joint. But its association with the inclination of the articular eminence (IAE) is unknown. This study aimed to compare IAE between patients with CSP and without CSP. Methods Cone-beam computed tomography images of 90 patients with TMD (mean age of 45.6 years, 69 with CSP, 21 without CSP) and 20 participants without TMD and CSP (mean age of 41.3 years) were measured to compare IAE and depth of the glenoid fossa (DGF) Results IAE and DGF showed a positive correlation among all the participants. Compared with the participants without TMD and CSP, the TMD patients without CSP presented a similar IAE but with a significantly higher value of DGF ( p < 0.05); in contrast, the TMD patients with CSP presented a significantly greater IAE and DGF ( p < 0.05). No bilateral differences in IAE and DGF were observed in all the participants. Except the male patients with CSP had a deeper fossa than did the female, no differences in IAE and DGF according to gender were observed. Conclusions TMD patients with CSP seem to have a deep glenoid fossa with steep eminence which might be considered one characteristic imaging feature.
... Studies considering that between 40% and 75% of the population of Brazil presents at least one sign of TMD, such as the presence of joint sounds in Temporomandibular Joint (TMD); and 33% have at least one symptom such as, facial or TMD pain [4]. The symptoms characterized chiefly by pain in the muscle and/or temporomandibular joint (TMD), TMD noises, restriction of mandibular movements, and deviation or limitation of mouth opening [2,[5][6][7]. Many clinicians consider persistent pain in the general orofacial region not clearly identifiable as headache to be TMD [3]. ...
... Mastication is an almost natural and subconscious activity in daily life. It has been shown that even healthy individuals chew more on either one right or left side (either left or right) of the dental arch (preferred chewing side) [1][2][3][4][5][6]. The habit of chewing predominantly on one side has been called mastication predominance. ...
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Purpose: The purpose of this study was to investigate the effects of prosthetic interventions in patients with Kennedy Class Ⅱ (unilateral missing posterior teeth) on mastication predominance. Methods: The subjects comprised patients with Kennedy Class II and healthy dentate volunteers (HD group). The subjects were asked to freely chew the test foods (chewing gum, beef jerky, and peanuts). Electromyographic activity of the bilateral masseter muscles was recorded twice (before and after prosthetic intervention). The chewing side (right or left) was judged by the level of the root mean square electromyographic amplitude. Mastication predominance was assessed using the mastication predominance index (MPI; range 0–100%). Each patient was restored with a removable partial denture (RPD) or an implant-supported fixed prosthesis (IFP). The effects of prosthetic interventions were statistically evaluated by the differences between MPI before and after prosthetic interventions (pre-MPI and post-MPI , respectively). Results: There was a significant difference between pre-MPI of patients wi th Kennedy Class II and MPI of the HD group (HD-MPI) for all test foods (P < 0.0001). Statistical analysis also demonstrated a significant difference between pre-MPI and post-MPI measured with each of the three food items in both the RPD and IFP groups (P < 0.0001). Multiple comparisons revealed that post-MPI in the IFP group, but not in the RPD group, was statistically comparable with HD-MPI, although there were no significant differences among the three gr oups when MPIs were calculated using peanuts. Conclusions: Prosthetic interventions improved mastication predominance in patients with Kennedy Class Ⅱ patients. Depending on the food type, IFP might contribute to better improvement of mastication predominance than RPD depending on food.
... Mastication, performed predominantly on one side of the dentition, is known as a chewing-side preference [10]. Although mastication may occur bilaterally, it has been reported that the majority of people preferably chew on one side [10][11][12]. Some previous studies have shown no significant prevalence between a right-or leftside preference of mastication [10,11], while others have reported a predominance on the right-side [13][14][15]. ...
Article
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Objective: To evaluate the prevalence of incidental tem-poromandibular joint findings on brain and orbit magnetic resonance imaging scans and assess if these findings are associated with symptoms. Methods: Our sample comprised 64 males (46.4%) and 74 females (53.6%), mean age 54.75±17.45 (range: 18-87). Data collected from each temporomandibular joint included articular displacement, articular effusion, condyle flattering, condyle erosions, capsule enhancement, and bone marrow edema. Dichotomous data as to temporomandibular joint-related symptoms such as headaches, earaches, dizziness, clicking or grating sound, pain or soreness of the joint, limited mouth opening, locking of the jaw, facial muscle pain, unexplained teeth pain, neck pain or stiffness and difficulty swallowing, were acquired during telephone interviews. Results: The most frequent finding was disc displacement (39.9% on the right side and 47.8% on the left), followed by condyle flattering (33.3% on the right side and 44.2% on the left). All findings, except bone marrow edema, were significantly more frequent on the left side than the right. Significant associations were found between incidental findings in the temporomandibular joint and earaches (odds ratio 2.759, P=0.043), dizziness (odds ratio 2.325, P=0.031), a clicking or grating sound (odds ratio 6.492, P=0.002) and facial muscle pain (odds ratio 11.255, P=0.003). Conclusions: Incidental findings of temporomandibular joint degenerative features were commonly found on the brain and orbit magnetic resonance imaging. Incidental findings on the temporomandibular joint were associated with earaches, dizziness, a clicking or grating sound and facial muscle pain.
... Studies have suggested that anterior disc derangement can be associated with chewing hard food. 25 This study has confirmed a significant association of stress/anxiety to TMDs in accordance to other studies. 6,26 Emotional stress has an influence on muscular activity and occlusion. ...
Article
Full-text available
Background: Temporomandibular disorders (TMDs) comprise of a variety of clinical signs and symptoms such as joint sounds, muscle tenderness, joint tenderness, deviation, deflection, pain on mouth opening, protru­sive, lateral movement and limited mouth opening which can be the re­sult of trauma, stress, gum chewing, hard food biting habits, bruxism, long dental appointment. This study was aimed to determine the prevalence of temporomandibular disorders in Nepalese population in Eastern Nepal. Methods: The study was performed from May 2018 to Oct 2018. All the patients who came to the Department of Oral Medicine and Radiology, Nobel Medical College and Teaching Hospital (NMCTH) and health camps in Eastern part of Nepal were included. The self-administered questions were asked to the subjects about demographic data, different signs and symptoms of TMDs and etiological factors responsible for it. Results: More than two thirds of the study sample (83.96%) in the present study had one or more clinical signs and symptoms of TMDs. Deviation of mandible on mouth opening and clicking sound made up the highest per­centage. Females were reported to have significantly higher prevalence of TMDs signs and symptoms than male. Disc displacement was the most prevalent disorder followed by myofascial pain and degenerative joint dis­order. Conclusions: The results of this study show that a significant percentage of the population has signs and symptoms of TMDs. Measures should be taken to prevent and treat TMDs in this part of the world.
... Since the number of lefthanders with n=5 was extremely small, the validity of this comparison is however very low. Moreover, it is conceivable that not only the handedness, but also the side of the dominant leg 51 or of the preferred chewing side, [52][53][54][55] has an influence on posture and postural control. Since such influencing variables have not been considered in previous investigations, this assumption is purely hypothetical in nature with regard to postural standard values. ...
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Objective: Many people of all ages suffer from vertigo due to different reasons. The comparison of patient data with standard values can highlight deteriorations or changes in postural control and thus indicate, for example, an increased risk of falling. Our aim is to measure standard values for the postural control of young healthy women. Design: Observational study. Setting: Institute of Occupational Medicine, Social Medicine and Environmental Medicine, Goethe-University Frankfurt/Main. Participants: 106 healthy German female subjects aged between 21 and 30 years (25±2.7 years) were measured. Their average body mass index (BMI) was 21.1±2.61 kg/m². Outcome measures: A pressure measuring platform was used to measure the weight distribution and postural sway in habitual standing. Median, tolerance range and CI were calculated. Results: Height, weight and BMI are comparable to the average young German female population. The load distribution between right and left foot was 49.91%:50.09%. The forefoot was less loaded than the rear foot (33.3%:66.67%). The right rear foot carried most of the body weight (34.34%). The average body sway was 9.50 mm in the frontal and 13.00 mm in the sagittal plane. Conclusions: Standard values for the postural control of the women aged 21-30 years correlate with the already collected data of healthy subjects and can therefore be described as representative. The standard values enable diagnosing and treating impaired balance.
... Se genera debido a causas de origen central o periféricas 9 y se asocia a fuerzas asimétricas durante el máximo apriete y asimetría facial 10 y de la actividad muscular 11 . Respecto a la patología y sintomatología temporomandibular, se ha visto que existe hiperactividad muscular en el lado asociado al hábito masticatorio unilateral 11 y presencia de patología articular como dolor a la palpación y desplazamiento discal ipsilateral al lado de la masticación 9,12 . ...
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Objective: The aim of this study was to determine the relationship between the habitual chewing side and the presence of temporomandibular disorders (TMD) in young adults. Materials and methods: An analytical case-control and simple blind study was performed on 70 young adult subjects (22-26 years) from the Faculty of Dentistry of the University of Chile. The masticatory functional angle (MFA) was used to determine the habitual chewing side in all subjects, as well as applying the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) in order to determine the type of TMD and the most prevalent side. Data were analysed using Chi squared test and Fisher's exact test (95% CI). Results: A total of 56 subjects (80.0%) were unilateral chewers and 14 (20.0%) were bilateral chewers. A diagnosis of TMD was made in 34 (48.6%) subjects according to RDC/TMD, while 36 individuals (51.4%) showed no evidence of any disorder. There were no differences between unilateral chewing and the presence of TMD (p=0.63). There was a high trend between unilateral chewing and presence of joint disease (groups ii and iii, RDC/TMD) (p=0.06). Conclusion: Despite a high trend between unilateral chewing and joint disease observed, the relationship between the type of chewing and TMD has not been established. No relationship was found between the chewing side and its coincidence with the disease side. This could be because of the different factors involved in TMD.
... In the TMJ, proprioception can be affected by TMJ disorder (TMD) [1], ankylosis [32], or hypermobility [9]. Interestingly, strong preference in chewing side has been linked to increased risk of TMD and to osseous changes in the TMJ in asymptomatic people [33,40,42]. ...
Article
Laterality of function in the orofacial musculature suggests there may be side-to-side asymmetry of proprioceptive acuity in lip movement compared to the temporomandibular joint (TMJ). In the present work, 14 young adults were tested for acuity of lip and TMJ closure movements onto plugs varying from 5 to 8 mm without visual feedback. Testing was conducted on both left and right sides, using the same psychophysical task and stimuli. Results showed superior proprioceptive acuity at the lips, with no significant side effect. However, there was side-to-side asymmetry in the correlations between proprioceptive performance for the two anatomical structures, with performance on the right side strongly correlated but not on the left. This is consistent with the need for coordination between structures during chewing. When acuity at different points in the stimulus range was examined, the right side lips were better with small stimuli. Overall, results support enhanced use-specific proprioception.
... Se genera debido a causas de origen central o periféricas 9 y se asocia a fuerzas asimétricas durante el máximo apriete y asimetría facial 10 y de la actividad muscular 11 . Respecto a la patología y sintomatología temporomandibular, se ha visto que existe hiperactividad muscular en el lado asociado al hábito masticatorio unilateral 11 y presencia de patología articular como dolor a la palpación y desplazamiento discal ipsilateral al lado de la masticación 9,12 . ...
Article
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Objective The aim of this study was to determine the relationship between the habitual chewing side and the presence of temporomandibular disorders (TMD) in young adults. Materials and methods An analytical case-control and simple blind study was performed on 70 young adult subjects (22-26 years) from the Faculty of Dentistry of the University of Chile. The masticatory functional angle (MFA) was used to determine the habitual chewing side in all subjects, as well as applying the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) in order to determine the type of TMD and the most prevalent side. Data were analysed using Chi squared test and Fisher's exact test (95% CI). Results A total of 56 subjects (80.0%) were unilateral chewers and 14 (20.0%) were bilateral chewers. A diagnosis of TMD was made in 34 (48.6%) subjects according to RDC/TMD, while 36 individuals (51.4%) showed no evidence of any disorder. There were no differences between unilateral chewing and the presence of TMD (p=0.63). There was a high trend between unilateral chewing and presence of joint disease (groups II and III, RDC/TMD) (p=0.06). Conclusion Despite a high trend between unilateral chewing and joint disease observed, the relationship between the type of chewing and TMD has not been established. No relationship was found between the chewing side and its coincidence with the disease side. This could be because of the different factors involved in TMD.
... Tay et al. (1989) suggested that subjects with severe TMD tend to divert chewing to one side. Ratnasari et al. (2011) ound a significant predominance of the PCS on the ipsilateral side of anterior disc displacement during mastication of hard food. These patterns of characteristic movements seem to be adaptive responses that allow chewing to occur with the least amount of pain and damage. ...
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To date, masticatory laterality has not been fully examined as a parameter for evaluating tempro-mandibular disorders (TMD).This cross-sectional study included160 fully dentate dental professionals (mean 27 years old). Masticatory laterality was evaluated by using the observed preferred chewing side test. Muscle pain, tempro-mandibular joint (TMJ) pain, clicking, ranges of vertical and lateral mouth opening and deviation during mouth opening were also evaluated. Chi-square tests were used for statistical analyses; p 0.05 was considered significant. The prevalence of masticatory laterality among the study participants was 60%; 86.5% of the participants with masticatory laterality chewed on the right side. Forty percent of the participants chewed bilaterally. Of the symptoms evaluated, deviation was the most common symptom among participants with TMD and masticatory laterality (69.1%-65.5%), followed by clicking (66.1% of participants with TMD and62.5% of those with masticatory laterality).Deviation was associated with TMD and masticatory laterality; no association was found between clicking and TMD or masticatory laterality. Seventy-two percent of participants with TMD chewed unilaterally and 28% chewed bilaterally Our results demonstrated a strong association between TMD and masticatory laterality, suggesting, within the limitations of this study, that people who have masticatory laterality may be more susceptible to TMD, especially unilateral TMD.
... Se genera debido a causas de origen central o periféricas 9 y se asocia a fuerzas asimétricas durante el máximo apriete y asimetría facial 10 y de la actividad muscular 11 . Respecto a la patología y sintomatología temporomandibular, se ha visto que existe hiperactividad muscular en el lado asociado al hábito masticatorio unilateral 11 y presencia de patología articular como dolor a la palpación y desplazamiento discal ipsilateral al lado de la masticación 9,12 . ...
Conference Paper
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Objective: Several factors are involved as etiologic in temporomandibular disorders. The overload and lack of homeostasis are situations that should be analyzed. Unilateral chewers have an asymmetric behavior that could generate such a situation. In order to determine the association between chewing side preference and TMD in young adults, a descriptive - simple blind study was performed in 70 subjects belonging to the Faculty of Dentistry of the University of Chile. Method: The Functional Planas´s Angle was used to determinate the preference chewing side. The RDC/TMD criteria were applied to all subjects in order to determine the type of pathology and craniofacial side which was evidenced. Data were analyzed using Chi Square Test. Result: The TMD´s sample consisted with 37.1% men and 62.9% women. 80.0% of the subjects were unilateral chewers and 20.0% were bilateral chewers. 35 subjects (50.0%) had at least one group of pathology according to RDC / TMD and 35 subjects (50.0%) had no pathology. No differences were found regarding side of chewing. Chi2 = 0.35. The comparison between subjects with bilateral and unilateral chewing regarding on the presence or absence of joint pathology comprising groups 2 and 3 RDC / TMD showed no differences between groups. Chi2 = 1.36. Conclusion: No significant differences were observed between chewing side and temporomandibular ipsilateral pathology. Further studies are needed to relate the joint pathology with chewing side including variables as parafunctional habits and age.
... A wide range of variation for the percentage of chewing preference has been reported, in the order of 45 to 70% of the subjects [3-5, 7, 10]. Our results, in line with previous reports, indicate that most people show preference to one side in their chewing pattern; but as the results indicate and some authors have mentioned [5,17], this preference could be more conspicuous when it comes to hard food. It has been reported that the bite force differs in the two sides of the mouth and the side on which more bite force can be exerted is more likely to be preferred for chewing [4]. ...
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Preferred chewing side is a still controversial matter and various methods used have yielded some inconsistencies. The aim of this study is to compare the preference determined in different conditions. Nineteen healthy subjects were offered hard (walnut) and soft (cake) foods, while the electromyography was recorded from their masseter muscles, in 2009 in the Research Center of Physical Medicine and Rehabilitation, Tabriz University of Medical Sciences, Tabriz, Iran. Four occurrences were determined as the side of the first chews/all chews in the two food types, and then analyzed for correlations and agreements. For hard food 73.68% and for soft food 57.89% of the subjects showed preference. The comparison of all chews showed a highly significant preference towards the right side in both food types (p=0.000 & 0.003). There was both correlation and agreement between the first chew preferences in both food types, and an agreement between the first and all chew preferences in the hard food. Therefore, there seems to exist some laterality in mastication, which is more explicit when using hard food and assessing all chews.
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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.
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Background: Interactions within the musculoskeletal system have been investigated and confirmed in numerous studies. Objectives: Since there are no standard values for the posture of healthy persons, this study attempts to define reference values for the upper body posture in healthy men. Material and methods: A 3-dimensional back scan was performed to quantify the upper back posture while habitually standing. Tolerance regions for habitual posture were calculated, including the upper and lower limit for 95% of all values. Furthermore, the left and right limit of the confidence interval (CI) was carried out. Group differences were tested by using the t-test or the Wilcoxon-Mann-Whitney U test. Results: Height, weight and body mass index (BMI) of the participants were comparable to those of the average young German males. The spinal column was marginally twisted to the right. The spinal curves, defined by the thoracic or lumbar flexion angle, and the kyphosis and lordosis angle, indicated that the angle in the thoracic spine area was larger than that in the lumbar region. Consequently, a more kyphotic posture was observed in the sagittal plane. The habitual posture was slightly scoliotic, with a rotational component (scapular depression left, right scapula marginally located more dorsally, high state of pelvic left, iliac left further rotated posteriorly and simultaneously tilted further ventrally). No significant difference between right and left-handed persons could be proven. Conclusions: Video raster stereography is a suitable method to measure the 3-dimensional back surface. Using this method for healthy young men, we observed that they had an almost ideally balanced posture with minimal ventral body inclination and a marginal scoliotic deviation. The normal values allow a better comparison of data between different studies of body posture.
Article
Aims: To assess the influence of clenching side and location (ie, tooth) on the bite force necessary to induce pain or discomfort in patients with unilateral anterior disc displacement (ADD) of the temporomandibular joint (TMJ). Methods: A total of 17 patients with unilateral ADD diagnosed clinically and with magnetic resonance imaging were included. A bite force meter was positioned at each of four experimental positions: the mandibular first premolars and first molars, bilaterally. Subjects were instructed to clench on the bite force meter until they felt pain or discomfort in the orofacial area and to report the location of the pain. Differences in pain location (ADD side versus contralateral side) and in the bite force thresholds for eliciting pain or discomfort were assessed by means of the paired t test and Wilcoxon signed-rank test. Results: Only 18% of subjects (3 out of 17) reported pain in the TMJ with ADD during clenching at the ipsilateral molar, whereas 65% (11 out of 17) reported joint pain during clenching on the contralateral molar (P = .005). At the molars, the mean ± standard deviation bite force necessary to induce pain was 241.2 ± 135.5 N on the side with ADD and 160.9 ± 78.0 N on the contralateral side. The mean molar bite force necessary to induce pain on the side with ADD was significantly higher than that on the contralateral side (P = .002). Conclusion: Patients with unilateral ADD had fewer reports of TMJ pain and discomfort when they were molar clenching on the ipsilateral side compared to molar clenching on the contralateral side.
Article
We aimed to investigate mastication predominance in healthy dentate individuals and patients with unilateral posterior missing teeth using objective and subjective methods. The sample comprised 50 healthy dentate individuals (healthy dentate group) and 30 patients with unilateral posterior missing teeth (partially edentulous group). Subjects were asked to freely chew three kinds of test foods (peanuts, beef jerky and chewing gum). Electromyographic activity of the bilateral masseter muscles was recorded. The chewing side (right side or left side) was judged by the level of root mean square electromyographic amplitude. Mastication predominance was then objectively assessed using the mastication predominant score and the mastication predominant index. Self-awareness of mastication predominance was evaluated using a modified visual analogue scale. Mastication predominance scores of the healthy dentate and partially edentulous groups for each test food were analysed. There was a significant difference in the distribution of the mastication predominant index between the two groups (P < 0·05). The mastication predominant score was weakly correlated with self-awareness of mastication predominance in the healthy dentate group, whereas strong correlation was observed in the partially edentulous group (P < 0·05). The results suggest that the individuals with missing unilateral posterior teeth exhibited greater mastication predominance and were more aware of mastication predominance than healthy dentate individuals. Our findings suggest that an objective evaluation of mastication predominance is more precise than a subjective method.
Article
Objective: The aim of this study was to examine the validity of objective assessment of actual chewing side by measurement of electromyographic (EMG) activity of the bilateral masseter muscles upon chewing test foods. Design: The sample consisted of 19 healthy, dentate individuals. The subjects were asked to chew three types of test foods (peanuts, beef jerky, and chewing gum) for 10 strokes on the right side and then on the left side, and instructed to perform maximum voluntary clenching for 3s, three times. EMG activity from the bilateral masseter muscles was recorded. The data were collected in three different days. The root mean square EMG amplitude obtained from the maximum clenching task was used as the maximum voluntary contraction (MVC). Then, the level of amplitude against the MVC (%MVC) was calculated for the right and left sides on each stroke. The side with the larger %MVC value was judged as the chewing side, and the concordance rates (CRs) for the instructed chewing side (ICS) and the judged chewing side (JCS) were calculated. Intraclass correlation coefficients (ICCs) of the CRs were calculated to evaluate the reproducibility of the method. Results: High CRs between the ICS and JCS for each test food were recognized. There were significant ICCs for beef jerky (R=0.761, P<0.001) and chewing gum (R=0.785, P<0.001). Conclusions: The results suggested that the measurement of EMG activity from the bilateral masseter muscles may be a useful method for the objective determination of the actual chewing side during mastication.
Article
Chewing-side preference (CSP) may be associated with temporomandibular disorders. However, little information exists regarding whether CSP will lead to osseous changes of temporomandibular joint (TMJ) in asymptomatic participants. The aim of this study was to investigate the relationship between osseous morphology of TMJ in asymptomatic participants with CSP and without CSP. Of the 121 healthy dentate participants, 35 participants with left CSP, 38 with right CSP and other 48 without CSP were scanned by cone-beam computed tomography. The dimensions of the reconstructed images of opposing TMJs were compared. Statistical analyses were performed using spss 16.0 software. The results showed that there were no significant differences between the dimensions of bilateral structures of the TMJ (P1 > 0·05) in participants without CSP. However, the posterior–superior, posterior and lateral joint space of the preferred side were smaller than that of the unpreferred side in participants with CSP (P2 < 0·01) and bilateral TMJ in participants without CSP (P3 < 0·01). In addition, width of condylar neck of the unpreferred side both in sagittal and perpendicular to the long axis of condyle views was greater than that of the preferred side in participants with CSP (P2 < 0·01) and bilateral TMJ of participants without CSP (P4 < 0·01). Also, the inclination of articular eminence of the preferred side in view perpendicular to the long axis of condyle was less than that of the unpreferred side (P2 < 0·05). These findings suggest CSP affects osseous morphology of TMJ in asymptomatic participants.
Article
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PURPOSE: the study was conducted in order to investigate the difference among groups with class II and class III dentofacial deformities regarding reported chewing side preference and head inclination during chewing and to determine the intra-group predominance for these features when compared to a control group. METHODS: twenty-five volunteers aged from 15 to 34 years took part in the study, 12 of them with a diagnosis of class II dentofacial deformity, 13 with class III dentofacial deformity, and 10 control volunteers aged from 18 to 32 years matched for sex and age to the groups with deformity. The subjects were questioned on the presence of a chewing side preference and were recorded during habitual chewing of a cornstarch cookie for analyzing head posture through the images. RESULTS: there was no difference among the groups regarding reported chewing side preference, although the groups with dentofacial deformities had a significant predominance of reported chewing side preference. The groups with dentofacial deformities showed a greater predominance of head inclination during chewing when compared to the control. CONCLUSION: individuals with dentofacial deformities may show a chewing side preference and changes in head posture during chewing.
Article
The aim of the present study was to assess the disk-condyle-fossa relationship through magnetic resonance imaging and determine its association with clinical signs and symptoms of temporomandibular disorder in patients with myofascial pain and disk displacement (with and without reduction). Sixty-two female patients with complaints of pain were clinically examined using the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) and divided into the following groups: Group I, myofascial pain (n = 19); Group IIa, disk displacement with reduction (n = 32); and Groups IIb and IIc, disk displacement without reduction (n = 11). Classification of disk position was based on the positioning on a clock face (> or < than 11 o'clock) and condylar excursion was determined as (1) the proximal side of the apex of the articular eminence; (2) at the level of the articular eminence; and (3) beyond the apex of the articular eminence. Condylar position was determined in the sagittal images based on Gelb's template (normal, posteriorly displaced). Pain was assessed using a visual analogue scale (VAS). The univariate logistic regression, Mann-Whitney, Kruskall-Wallis and Pearson's correlation tests were used in the statistical analysis (P < or = .05). No significant association was found between the independent variables (condylar position, disk position, and condylar excursion) and the dependent variables (pain, maximal opening of the mouth, maximal lateral movement). However, there was a significant association between increased condyle excursion and pain (P = .035) and also maximum mouth opening movement was associated with lateral movement (P = .01; r = 0.31). Increase in condyle excursion may significantly influence pain perception in TMD patients. The type of dysfunction and severity of alterations on the imaging exams were not related to the severity of pain or range of motion of the mandible.
Article
The purpose of this study was to clarify whether there was a difference in the masticatory function between two masticatory path patterns: a convex closing path and a concave closing path. For 80 healthy subjects, the masticatory function (masticatory muscular activity, mandibular movement, and masticatory performance) when chewing a gummy jelly was recorded. Out of the 160 chewing cases (80 subjects chewing on either side), 65 cases (Group I) in which the incisal point opened in a linear or concave manner toward the working side and closed in a convex manner, and 15 cases (Group II) in which the opening path was the same as that in Group I, but the closing followed a concave path, were selected. For the masticatory function, the integral values per unit time of masseter and temporal muscular activities, the gape and masticatory width, the indicators representing the stability of movement path, and the glucose extraction from chewing gummy jelly were measured and compared between the two groups. The integral values of muscular activities and the amount of glucose extraction were significantly greater in Group I. The gape and masticatory width were not significantly different between the groups. The values of the indicators representing the stability of path were smaller in Group I than in Group II. From these results, it was suggested that there was a functional difference between Group I (with a convex closing path) and Group II (with a concave closing path), and that Group I had a superior masticatory function to Group II.
Article
To clarify the usefulness of the standard deviation (SD) and SD divided by the opening distance (SD/OD) of the opening lateral, closing lateral, and vertical components of the masticatory path as indicators of the stability of masticatory movement path. Fifty subjects masticated softened chewing gum on the unilateral side for 20s, and the movement of the mandibular incisal point was recorded. For 10 cycles from the 5th cycle of 100 cases (50 subjects chewing on either side), a picture comprising each cycle path was displayed and classified subjectively into three categories (stable, unstable, and unknown) by three evaluators. The 18, 17, and 19 cases that were assessed as stable, unknown, and unstable were classified as Groups A, B, and C, respectively. For 10 cycles from the 5th cycle, the SD and SD/OD of the opening lateral, closing lateral, and vertical components representing the movement path as indicators for the stability of the path were calculated and compared among the three groups. The SD and SD/OD of the opening lateral, closing lateral, and vertical components were small in Group A, increased in Group B, and increased further in Group C. Significant differences were observed among the groups. These differences were more apparent in the assessment using the SD/OD than in the assessment using the SD. The SD and SD/OD of the components representing the movement path were useful as indicators for the stability of the movement path and the SD/OD appeared to be particularly useful.
Article
To clarify the masticatory path patterns of the mandibular incisal point during mastication of softened chewing gum with regard to gender difference. One hundred healthy subjects (50 males and 50 females) were asked to chew softened chewing gum on one side at a time (right side and left side) and the movement of the mandibular incisal point was recorded using MKG K6I. After a catalog of path patterns was made, the movement path was classified into one of the pattern groups, and then the frequency of each pattern was investigated. A catalog of path patterns consisting of the three types of opening path (op1, linear or concave path; op2, path toward the chewing side after toward the non-working side; op3, convex path) and two types of closing path (cl1, convex path; cl2, concave path) was made. The movement path was classified into one of seven patterns, with six patterns being from the catalog and a final extra pattern in which the opening and closing paths crossed. The most common pattern among the subjects was Pattern I, followed by Patterns III, II, IV, V, VII, and VI, in that order. The majority of cases, 149 (74.5%) of 200 cases, showed either Pattern I (op1 and cl1) or Pattern III (op2 and cl1). There was no significant difference between the two genders in the frequency of each pattern. The movement path could be classified into seven patterns and no gender-related difference was found in the frequency of each pattern.
Article
To determine whether chewing side preference is related to handedness and lateral asymmetry of occlusal characteristics, muscular force and temporomandibular disorders (TMD) in a dentate population. One hundred and seventeen dentate adults participated in this cross-sectional study. Static and dynamic occlusal characteristics were determined at the maximal intercuspal position and at the lateral excursions by scanning interocclusal records and analysing them using image software. Unilateral maximum bite force and finger-thumb grip force were measured by means of a gnathodynamometer. TMD were assessed according to the Research Diagnostic Criteria for TMD. Chewing side preference and masticatory laterality were determined by observing the jaw's movement while each subject chewed silicone. Asymmetry or side difference of the variables was calculated. Correlation between side difference variables and masticatory laterality was studied using Spearman correlation coefficient. Fifty-nine subjects chewed on the right, 15 on the left and 43 chewed on both sides. There was no relationship between preferred chewing side and handedness, lateral asymmetry of TMD or side difference in finger-thumb grip force. Significant and positive correlations were observed between masticatory laterality and side differences in bite force and side differences in occlusal contact area at intercuspal position (P<0.01). Chewing side preference in a dentate population is related to lateral asymmetry of bite force and asymmetry of occlusal contact area at the intercuspal position but not to handedness.
Article
This study investigated the prevalence of a preferred chewing side (PCS) and associations between a PCS and signs of temporomandibular disorders (TMD), antagonist contact and prosthetic restoration. A population representative sample of 4086 adults of the cross-sectional epidemiologic 'Study of Health in Pomerania' (SHIP-0) (age range 20-80 years, female 50.2%) was divided in two groups by the presence or absence of a PCS. PCS was evaluated by a questionnaire. Chi-squared tests and multiple logistic regression were used to determine the impact of the relation between a PCS and signs and symptoms of TMD as well as dental factors. The prevalence of a PCS was 45.4%. Women between 40 and 69 years reported more frequently a PCS. There was a preference for the right side (64%). The following independent variables were significantly associated with a PCS: subjective unilateral pain in the temporomandibular joint (TMJ), odds ratio (OR) 2.4; subjective unilateral joint clicking, OR 1.7; unilateral TMJ/muscle pain on palpation, OR 1.6/OR 1.3; loss of one supporting zone (Eichner-Classification), OR 1.9; loss of both supporting zones on one side, OR 2.2, one supporting zone left, OR 1.4; presence of a removable partial denture, OR 1.6; presence of an attachment restoration, OR 1.5. A PCS was found in almost half the study population and was associated with unilateral signs of TMD, most of all TMJ pain and asymmetrical loss of antagonist contact. Despite replacement of lost teeth not all restorations seemed to support bilateral mastication.
Article
Forty-two temporomandibular joints (TMJs) in 21 asymptomatic volunteers were visualized by magnetic resonance imaging (MRI). The subjects, 12 males and nine females, were between 23 and 43 years of age and had no history of TMJ pain, joint noise, limited opening, or previous treatment for TMJ disorder. A cephalometric head-holder was designed to position the TMJ in an accurate and reproducible manner and multisection parasagittal images were obtained perpendicular to the longitudinal axis of the condyle. MR images depicted anterior disc position in 32% of the asymptomatic joints (8/24 males, 5/18 females). Anterior disc position in asymptomatic subjects may be a predisposing factor to TMJ dysfunction or simply an anatomic variant whose prevalence must be considered when evaluating TMJ dysfunction.
Article
To study lateral bolus placement during mastication, referred to as masticatory lateral preference, fifteen males and ten females chewed sugarless gum for 15, 20 and 25 s, and visual inspections were done of either right or left side bolus placements. In each of three series of observations, there were no significant differences between right or left side bolus placements. Three consecutive spot checks, in single subjects, showed that lateral preference occurred at random. However, information on a favoured chewing side predicted fairly reliably the side of observed masticatory lateral preference. Observed lateral preference could not be predicted from hand laterality. Consistent and predominant right or left lateral preference was, presumably, an expression of mainly motivational chewing behaviour.
Article
Differential, functional loading of the mandibular condyles has been suggested by several human morphologic studies and by animal strain experiments. To describe articular loading and the simultaneous forces on the dental arch, static bites on a three-dimensional finite element model of the human mandible were simulated. Five clenching tasks were modeled: in the intercuspal position; during left lateral group effort; during left lateral group effort with balancing contact; during incisal clenching; and during right molar clenching. The model's predictions confirmed that the human mandibular condyles are load-bearing, with greater force magnitudes being transmitted bilaterally during intercuspal and incisal clenching, as well as through the balancing-side articulation during unilateral biting. Differential condylar loading depended on the clenching task. Whereas higher forces were found on the lateral and lateroposterior regions of the condyles during intercuspal clenching, the model predicted higher loads on the medial condylar regions during incisal clenching. The inclusion of a balancing-side occlusal contact seemed to decrease the forces on the balancing-side condyle. Whereas the predicted occlusal reaction forces confirmed the lever action of the mandible, the simulated force gradients along the tooth row suggest a complex bending behavior of the jaw.
Article
The effect of balancing-side occlusal contact patterns on ipsilateral TMJ dynamics was evaluated in this study. Vertical displacement of the balancing-side lower second molar during clenching at canine edge-to-edge position, with 0 and 1 mm of inter-canine distance, was measured for 42 normal subjects in relation to their balancing-side occlusal contact. Balancing-side occlusal contact was classified into four following patterns; (1) simultaneous balancing-side and working-side contact (without clenching); (2) balancing-side contact (with clenching only); (3) no balancing-side contact (with or without clenching); and (4) exclusive balancing-side contact (no working-side contact). The vertical displacement of the balancing-side condyle, calculated from the displacement of the balancing-side second molar, showed three different types of displacement pattern. These three types showed distinctive incidence in relation to the pattern of balancing-side occlusal contact. It was revealed that balancing-side occlusal contact can affect the ipsilateral TMJ dynamics.
Article
To compare the prevalence and type of temporomandibular joint (TMJ) disk displacement in asymptomatic volunteers with those in patients. Bilateral oblique sagittal and oblique coronal intermediate-weighted magnetic resonance (MR) images of the TMJs in 58 patients with pain and dysfunction were analyzed and compared with corresponding MR images of 62 asymptomatic volunteers. Forty-five (78%) of 58 patients had disk displacement compared with 22 (35%) of 62 asymptomatic volunteers. Complete disk displacement was found in 46 (40%) of 115 joints in patients compared with three (2.4%) of 124 joints in asymptomatic volunteers, whereas partial disk displacement occurred in 26 (22.6%) and 27 (21.8%) joints, respectively. Two types of complete disk displacement, anterolateral and anterior, occurred frequently in patients, seldom in volunteers. Only minor differences were found between other types of disk displacement when prevalence in patients was compared with that of volunteers. The disk reduced to a normal position on open-mouth images in all joints in the volunteers compared with 76% of the joints in patients. TMJ disk displacement was less prevalent and was of a different type in asymptomatic volunteers compared with patients with pain and dysfunction.
Article
The purpose of this study is the objective and quantitative evaluation of masticatory laterality and its daily variability. Various foods with different textures were used to investigate whether food texture influenced masticatory laterality. Ten healthy subjects and seven foods were used. Recordings of chewing movements were repeated three times at intervals of 1 week. Masticatory laterality was assessed with an Asymmetry Index [AI: (number of right side strokes - number of left side strokes)/number of total strokes]. Medians and ranges of the three recordings were calculated. The observed AI ranges in the three trials were limited with the exception of two subjects. Among the other subjects, averages of the absolute values of the medians were from 32.5 to 73.4%. Statistically significant differences between the hardest food and softer foods were observed in absolute value of AI medians. Masticatory laterality could be evaluated by an AI. Eight of 10 subjects showed limited ranges of AI in three recordings. It should be noted that a few people actually chew on either side but might chew on one side only on a particular day. Hard food evoked more masticatory laterality, and seemed more appropriate for laterality examinations.
Article
Temporomandibular joint (TMJ) abnormalities cannot be reliably assessed by a clinical examination. Magnetic resonance imaging (MRI) may depict joint abnormalities not seen with any other imaging method and thus is the best method to make a diagnostic assessment of the TMJ status. In patients with temporomandibular joint disorder (TMD) referred for diagnostic imaging the predominant TMJ finding is internal derangement related to disc displacement. This finding is significantly more frequent than in asymptomatic volunteers, and occurs in up to 80% of patients consecutively referred for TMJ imaging. Moreover, certain types of disc displacement seem to occur almost exclusively in TMD patients, namely complete disc displacements that do not reduce on mouth opening. Other intra-articular abnormalities may additionally be associated with the disc displacement, predominantly joint effusion (which means more fluid than seen in any asymptomatic volunteer) and mandibular condyle marrow abnormalities (which are not seen in volunteers). These conditions seem to be closely related. Nearly 15% of TMD patients consecutively referred for TMJ MRI will have joint effusion, of whom about 30% will show bone marrow abnormalities. In a surgically selected material of joints with histologically documented bone marrow abnormalities nearly 40% showed joint effusion. Disc displacement is mostly bilateral, but joint effusion seems to be unilateral or with a lesser amount of fluid in the contralateral joint. Abnormal bone marrow is also mostly unilateral. Many patients have unilateral pain or more pain on one side. In a regression analysis the self-reported in-patient TMJ pain side difference was positively dependent on TMJ effusion and condyle marrow abnormalities, but negatively dependent on cortical bone abnormalities. Of the joints with effusion only one fourth showed osteoarthritis. Thus, there seems to be a subgroup of TMD patients showing more severe intra-articular pathology than disc displacement alone, and mostly without osteoarthritis. It should, however, be emphasized that patients with TMJ effusion and/or abnormal bone marrow in the mandibular condyle seem to constitute only a minor portion (less than one fourth) of consecutive TMD patients referred for diagnostic TMJ imaging. The majority of patients have internal derangement related to disc displacement, but without accompanying joint abnormalities. In patients with rheumatoid arthritis and other arthritides TMJ involvement may mimick the more common TMDs. Using MRI it is possible, in most cases, to distinguish these patients from those without synovial proliferation.