A preliminary study to find a possible association between occlusal wear and maximum bite force in humans

Abstract

Objective. The objective of the study was to investigate whether moderate-to-severe attrition is associated with maximum bite force in the first molar region. Methodology. Maximum bite force in the first molar region was measured for a total of 60 subjects having moderate-to-severe attrition of occlusal surface (experimental group) using a specially-designed piezoelectric sensor based bite force measuring device. An equal number of age, gender, height and weight matched controls (control group) were also subjected to bite force measurement for comparison. Results. The maximum bite force was found to be significantly lower (p < 0.05) in the experimental group [480.32 (153.40)] as compared to the controls [640.63 (148.90)]. While analyzing the possible etiology for occlusal wear mainly two reasons were elicited, i.e. history of parafunctional habits like use of known abrasive tooth powder (sub-group A) and Bruxism (sub-group B). However, there were many subjects in which no known definite etiological factors be attributed to occlusal wear (sub-group C). On analysing further with respect to the possibly correlated etiological factors with maximum bite force, no significant difference was found within the experimental sub-group. However, all three experimental sub-groups had significantly lower maximum bite force as compared to age, gender and BMI matched controls. Conclusion. A significantly lower maximum bite force was found to be associated with moderate-to-severe attrition as compared to subjects without attrition. However, no specific relation could be found between bite force and possible etiological factors like history of parafunctional habits, history of use of known abrasive tooth powder, etc.     

Relationship between occlusal curvatures and mandibular deviation in orthodontic patients with temporomandibular disorders

The aim of this study was to investigate the relationships between occlusal curvature (OC) and frontal craniofacial morphology in patients with and without temporomandibular disorders (TMD), using frontal cephalograms and a sophisticated measuring device (XYZAX S400A). Thirty-seven female orthodontic patients (mean age 24.0 years) were divided into a TMD group (n = 25) and no-TMD group (n = 12). In the TMD group, the lateral OCs of the mandibular second premolar, and first and second molars were significantly deeper on the deviated side than on the non-deviated side, and the anteroposterior OCs of the mandibular second premolar and first molar were also significantly shallower on the deviated side. In the no-TMD group, however, there were no significant differences in OCs between deviated and non-deviated sides. The differences between right and left lateral OCs in the mandibular second premolar and first and second molars, as well as the anteroposterior OCs in the mandibular first and second molars, showed significant correlations with mandibular deviation in the TMD group. On the other hand, in the no-TMD group, there was no significant correlation between OCs and mandibular deviation. The above results suggest that OCs might try to compensate for mandibular deviation in patients with TMD.     

Relationship between myoelectric activity in masticatory muscles and bite force

Myoelectric activity in the anterior and posterior temporalis and in the masseter muscle was assessed in five subjects biting unilaterally on a bite fork at 50, 100 and 200 N for 60 s. The bite fork was placed between the right first premolars and the first molars. The ipsilateral muscle activity was recorded first, and the contralateral side was evaluated 1 wk later. The relationship between exerted force and EMG-activity was expressed as ratios between EMG-activity and related bite force. EMG-activity increased with increasing force for all muscles tested. Linearity was found for the anterior temporal muscle, but not for the other muscles. Four of the subjects participated in an endurance test, exerting maximum bite force on the right side for as long as possible. The EMG activity of the right masseter muscle was closely related to bite force, in contrast to the other tested muscles. The activity of the left muscles increased at the end of the endurance test.     

Relationship between myoelectric activity in masticatory muscles and bite force

Myoelectric activity in the anterior and posterior temporalis and in the masseter muscle was assessed in five subjects biting unilaterally on a bite fork at 50, 100 and 200 N for 60 s. The bite fork was placed between the right first premolars and the first molars. The ipsilateral muscle activity was recorded first, and the contralateral side was evaluated 1 wk later. The relationship between exerted force and EMG-activity was expressed as ratios between EMG-activity and related bite force. EMG-activity increased with increasing force for all muscles tested. Linearity was found for the anterior temporal muscle, but not for the other muscles. Four of the subjects participated in an endurance test, exerting maximum bite force on the right side for as long as possible. The EMG activity of the right masseter muscle was closely related to bite force, in contrast to the other tested muscles. The activity of the left muscles increased at the end of the endurance test.     

Relationship between age and occlusal force in adults with natural dentition

Odontology - This study aimed to clarify the relationship between age and occlusal force in adults with natural dentition. A total of 385 adults (180 males and 205 females) with natural dentition...     

错[牙合]畸形患者直丝弓矫治器治疗后保持阶段[牙合]力及咬合接触变化的研究

目的研究青少年错(牙合)畸形患者在固定矫治器矫治后保持阶段,牙尖交错位时(牙合)力及咬合接触的变化。方法采用 T-ScanⅡ咬合测量分析系统记录分析21名青少年错(牙合)畸形患者结束固定矫治时及保持半年后(牙合)力及咬合接触情况,并进行统计分析。结果保持半年后,患者(牙合)力不对称指数无显著差异(P>0.05)、(牙合)力中心点更趋于理想位置(P<0.05)。(牙合)接触点数显著增加(P>0.05)、(牙合)接触点不对称指数明显减小(P<0.05)。结论保持阶段并非治疗结果的简单维持,牙位及咬合接触在此阶段仍有细微调整。本研究中,患者的咬合接触分布更趋于平衡,(牙合)的稳定性进一步提高,这对矫治结果的长期稳定有积极意义。     

The effect of periodontal surgery on bite force, occlusal contact area and bite pressure

BACKGROUND: Tooth mobility resulting from the loss of periodontal support or trauma induced by periodontal surgery may change the amount of bite force (BF) and bite pressure (BP) and number of occlusal contact areas (OCAs). The aim of the authors' study was to compare BF, BP and OCA of teeth with periodontal disease before and after periodontal surgery with similar values of healthy teeth. METHODS: The authors performed quantitative analysis of BF, BP and OCA using a pressure measurement film. Ten patients with periodontitis who needed periodontal surgery served as the test group. The authors took measurements of BF, BP, OCA and mobility (using Miller's Mobility Index) just before surgery and at one, four and 12 weeks after surgery. They also measured clinical attachment levels (CAL) before surgery and 12 weeks after surgery. Ten subjects without periodontitis served as the control group. RESULTS: Although BF and OCA increased the first week after periodontal surgery, analysis of variance (ANOVA) showed no statistically significant differences at a 95 percent confidence interval. There were statistically significant differences between first-week mobility and that at four and 12 weeks (P = .001). A factorial ANOVA showed significant interaction between BF and mobility (P < .05). CONCLUSIONS: The authors' findings suggest that changes in BF, BP and OCA were not affected by periodontal surgery. However, mean mobility values and BF are correlated. Further investigations of this measurement method involving larger study populations and a longer follow-up period are needed. CLINICAL IMPLICATIONS: It seems to be helpful to follow occlusal changes after periodontal surgery using a pressure measurement film. It also may be suggested that this measurement method could be used to evaluate the treatment prognosis.     

Relationship between habitual occlusal position and flat bite plane induced occlusal position in volunteers with and without temporomandibular joint sounds

The aim of this study was to assess whether temporomandibular joint (TMJ) sounds are associated with the difference between the habitual occlusal position (HOP) and the bite plane induced occlusal position (BPOP). Fifteen dental technician school students who had complete natural dentition, normal occlusion and who exhibited TMJ sounds were compared with fifteen healthy control subjects. HOP was recorded by voluntary jaw closing while in an upright position, and BPOP was recorded after wearing an anterior bite plane for a short period of time. Three interocclusal records were obtained in both positions with a vinyl polysiloxane material, and the recorded maxillomandibular relations were analyzed three-dimensionally and compared. Subjects with TMJ sounds had statistically larger differences between HOP and BPOP than controls (p<.05). Within this study population, an association was found between TMJ sounds and the difference between HOP and BPOP.     

Association of bite force with ageing and occlusal support in older adults

OBJECTIVES: The purpose of this study was to investigate the effect of ageing, occlusal support and TMJ condition and general health status on bite force in older adults. METHODS: The study sample consisted of 850 independently-living people over the age of 60 years. Bilateral maximal bite force in the intercuspal position was measured with pressure sensitive sheets. TMJ noise by palpation and limitation of mouth opening (less than 40 mm) were assessed. Subjects were grouped into three categories by occlusal support according to the Eichner Index. RESULTS: A multiple logistic regression analysis showed that whether participants had low bite force or not was significantly associated with gender, age, self-rated general health and occlusal support, but not TMJ noise or mouth opening limitation. Overall bite force showed a statistically significant but weak negative Spearman's correlation with age (r=-0.24, p<0.001). However, there was no significant correlation between age and bite force in the Eichner C group for males or in any of the Eichner classification for females. CONCLUSIONS: Decline of occlusal support and general health might translate into reduction of bite force with ageing in older adults. Since tooth loss is not physiological ageing but pathological ageing, it cannot be shown that reduction of bite force is a natural effect of ageing.     

Posterior occlusal support and bite force influence on the mandibular position

Three-dimensional mandibular displacement related to loss of posterior occlusal support was investigated. Five subjects, whose mandibular premolars and molars needed to be restored, were selected. Their experimental prostheses were removed in sequence from the most posterior to anterior. The more the absence of posterior occlusal support increased, the more condylar displacements were increased. On the other hand, maximum bite forces were decreased, by removing each prosthesis in sequence from posterior to anterior. These results suggest that condylar position would be easily displaced with low level bite force following loss of posterior occlusal support.     

Relationship between maximal bite force and tooth wear in bruxist and non-bruxist individuals

Objective

(i) To compare individuals with self-reported bruxism and non-bruxist individuals in terms of maximal bite force (MBF) and temporomandibular joint (TMJ) primary assessment parameters and (ii) to examine the relationship between MBF and tooth wear in these subjects.

Materials and methods

Twenty-nine bruxist subjects and 29 healthy controls were enrolled. MBF measurements were carried out by the use of bite force recorder. Tooth wear indices, maximal mouth opening, maximal lateral excursions and maximal protrusions were measured for every subject.

Results

MBF and tooth wear index scores were significantly higher in bruxists (p values <0.05) compared to non-bruxists. MBF and tooth wear index scores were found to be significantly correlated in the bruxist group (r = 0.79, p = 0.00). Less significant correlation was observed in the non-bruxist group (r = 0.38, p = 0.04). No differences in masticatory clinical examination parameters were identified between the groups.

Conclusion

This study is the first to show that MBF can increase in bruxist individuals and that the increase in MBF are correlated with tooth wear in bruxist subjects. Further studies regarding the possible role of MBF in bruxism are to be done.     

咬合垂直距离与咀嚼肌肌电、咬合力关系的研究

目的研究老年无牙颌患者垂直距离和咬合力、咀嚼肌肌电幅值的关系,为临床上确立正常垂直距离提供参考。方法研究对象来自浙江大学附属口腔医院就诊的10位老年无牙牙合患者,用常规法确定垂直距离,以正常咬合垂直距离为基准位(M位),间隔0.5 mm形成13个咬合垂直距离。应用咬合力计测量患者不同垂直距离的咬合力,同时用记录双侧颞肌前束、咬肌的肌电活动,对垂直距离、咬合力和肌电进行统计研究。结果 1无牙颌患者的咬合力与垂直距离呈正相关(P<0.05)。2标准化咬肌(NMM)和标准化颞肌前束肌电幅值(NATM)与垂直距离呈负相关(P<0.05)。3颞肌前束肌电/咬合力(ATM/BF)、咬肌肌电/咬合力(MM/BF)比值与着垂直距离呈负相关(P<0.05)。结论 1随着垂直距离的增加,最大咬合力增大,正常咬合垂直距离并非产生最大咬合力的区域。2随着咬合垂直距离的增加,咬肌的肌电活动明显下降,颞肌前束的肌电活动变化则不及咬肌明显。3咬肌肌电/咬合力、颞肌前束肌电活动/咬合力比值均随着咬合垂直距离的增加而减小。4在正常咬合垂直附近有一稳定区,该区内最大咬合力、咬肌以及颞肌前束的肌电活动均不出现明显变化。     

Relation of dietary preference to bite force and occlusal contact area in Japanese children

Summary  The purpose of this study was to examine the relationship of dietary preference to bite force and occlusal contact area in Japanese elementary school children. A total of 348 children, aged 7–12 years, from two public elementary schools located in Okayama Prefecture, Japan, participated in the study. Clinical examination included decayed, missing and filled teeth (dmft and DMFT), and total numbers of deciduous and permanent teeth. Bite force and occlusal contact area were measured using a pressure-detecting sheet. Dietary preference was assessed using a questionnaire in which the answers were given in like/dislike form. Mann–Whitney U- test and multiple logistic regression analysis were applied to analyse the data. In multiple logistic regression analysis after adjustment for age, gender and total number of teeth present, children who liked cabbage and celery showed significantly higher bite force ( P  =   0·05 and P  <   0·01, respectively) than those who disliked these. Children who liked cabbage and celery also showed higher occlusal contact area ( P  <   0·05 and P  <   0·01, respectively) than those who disliked these. The Japanese elementary school children who liked hard foods such as cabbage and celery showed higher bite force and higher occlusal contact area than those who disliked these foods. A positive attitude towards harder food items might contribute to healthy development of the masticatory apparatus.     

伴有颞下颌关节紊乱病的女性开患者的咬合力分析研究

目的探讨咬合因素对女性开!患者中颞下颌关节紊乱病（ TMD）发病的影响。方法选取女性开!患者102名,根据TMD的有无分为两组,伴有TMD的试验组有59名患者;不伴有TMD的对照组有43名患者。采用咬合力测试仪对两组患者进行咬合力、咬合接触面积、每一咬合接触点上的平均咬合压强和咬合重心的测试,并通过SPSS 11.0软件进行统计学分析。结果试验组的咬合力和咬合接触面积均小于对照组,两组间每一咬合接触点上的平均咬合压强和咬合重心的偏移无统计学差异。结论咬合力不足与开!女性TMD的发病有关。     

Influence of clenching intensity on bite force balance, occlusal contact area, and average bite pressure.

It has been difficult for investigators to simultaneously and reliably evaluate bite force in the intercuspal position with the area and location of occlusal contacts. This study was designed to investigate the variations in these parameters with respect to two factors: three levels of clenching and the preferred chewing side. Human subjects with normal occlusion were examined with a recently developed system (Dental Prescale Occluzer, Fuji Film, Tokyo, Japan). The three levels of clenching intensity were assessed by masseteric EMG activity and included the maximum voluntary contraction, and 30% and 60% of the maximum. The results indicated that the bite force and occlusal contact area on the whole dental arch increased with clenching intensity. In contrast, the average bite pressure, obtained by dividing the bite force by the contact area, remained unchanged regardless of the clenching intensity. As the clenching intensity increased, the medio-lateral position of the bite force balancing point shifted significantly (P<0.01) from the preferred chewing side toward the midline. The antero-posterior position remained stable in a range between the distal third of the first molar and the mesial third of the second molar. The bite force and occlusal contact area, which were mainly on the molars, increased with the clenching intensity, whereas the proportions of these two variables on each upper tooth usually did not change significantly. The exception was the second molar on the non-preferred chewing side. When comparisons were made between pairs of specific upper teeth of same name, usually no significant difference was found in bite force or occlusal contact area, regardless of the clenching level. Again, the exception to this observation was the second molar on the preferred chewing side, which had a larger area at the 30% clenching level. The results in normal subjects suggest that as the clenching intensity increases in the intercuspal position, the bite force adjusts to a position where it is well-balanced. This adjustment may prevent damage and overload to the teeth and temporomandibular joints.     

Automatic regulation of occlusal force because of hardness-change of the bite object

It is considered that the information of chewed food, such as size and texture, is important for smooth mastication. In this study, we analysed aspects of the control of occlusal force, by experimentally reproducing situations in which the hardness of food changed unpredictably during mastication, using a device that utilized a 3-sectioned urethane rubber piece with different hardness values. Seven healthy subjects were instructed to perform repetitive jaw open-close movements paced by a metronome (1.0 Hz) and to maintain constant occlusal force throughout the trial. Using the device, the following parameters were measured during the first to fifth strokes after changing the hardness, peak value, impulse, duration and time to peak of occlusal force in the waveform of occlusal force, cycle time of open-close jaw movements, jaw gape and maximum speed in the closing phase in the waveform of the jaw movements. Each parameter value was statistically analysed by anova with Fisher's least significant difference method (P < 0.05). Peak occlusal force, impulse and jaw gape were significantly affected by the change in hardness, while an increase in hardness caused increases in the values for peak occlusal force and impulse against the instruction, after which those values remained constant while the subjects occluded the same level of hardness. Our results indicate that the level of the resulting occlusal force is regulated automatically according to the hardness of the chewed food. We concluded that occlusal force was adapted for efficient mastication when the hardness of foods changes unpredictably.