F—l型数字力仪的研制与应用

作者运用电阻应变传感技术,结合大规模集成电路和液晶数字显示系统,成功研制了牙合力测定仪,其可在口腔中直接准确地测定牙齿的咬合力,为定量研究牙体牙周健康状况及修复治疗效果,提供较为准确的客观依据.本文介绍了一种新研制的数字式(牙合)力仪,并用此(牙合)力仪对正常50名青年男女进行(牙合)力测定,以供参考.     

A novel bite force recorder and maximal isometric bite force values for healthy young adults

Human bite forces have been studied with several types of equipment, and the maximal values reported have varied greatly. In the present study, a new bite force recorder was developed to measure human bite forces. When measuring maximal bite force, the mandible is, laterally and sagittally, almost in the intercuspal position, while the vertical opening of the jaws in the molar region is about 14 mm. Several teeth bite upon the housing. A quartz force transducer serves as a sensory unit. A microprocessor produces a numeric result, shown on a liquid crystal display (LCD). In order to adapt the sensor to be a part of a bite force recorder, we designed a unilateral housing of nonhardened tool steel. In laboratory calibration tests, a series of loads from 112.8 to 1691.5 N was used. The maximal bite forces of healthy undergraduate dental students, 15 men and 15 women, were investigated. The results for both genders remarkably exceeded the values previously reported for unilateral housings. The mean maximal bite force value in the molar region was 847 N for men and 597 N for women. The finding that pain or lack of muscular strength most often limited the clenching suggests that the actual masticatory potential was registered.     

The effect of maximum bite force on alveolar bone morphology

Authors – Thongudomporn U, Chongsuvivatwong V, Geater AF Objectives – To investigate to what extent maximum bite force contributes to alveolar bone morphology parameters, i.e. alveolar thickness, shape and arch width. Design – An observational cross‐sectional survey. Setting and Sample Population – One hundred and fifty one 12‐ to 14‐year‐old students from a secondary school in Hatyai City, Songkhla Province, Thailand. Material and Methods – Height, weight and maximum bite force of each subject were recorded. Alveolar bone morphology parameters were measured from study models. Results – Maximum bite force moderately correlated with alveolar thickness and shape (r = 0.31–0.44, p < 0.001), but weakly correlated with arch width (r = 0.03–0.05, p > 0.05). After adjusting for gender and body mass index (BMI), the maximum bite force significantly determined alveolar thickness and shape (p < 0.001), accounting for 10–20% of the variations. Boys were associated with larger posterior arch width (p < 0.01), where BMI was not associated with alveolar bone morphology parameters (p > 0.01) after Bonferroni correction for multiple testing. Conclusion – Maximum bite force had a selective influence on alveolar thickness and shape, but not on arch width.     

Bite force measurements with hard and soft bite surfaces

Bite force has been measured by different methods and over a wide variety of designs. In several instruments, the fact that bite surface has been manufactured with stiff materials might interfere in obtaining reliable data, by a more prompt activation of inhibitory reflex mechanisms. The purpose of this study was to compare the maximum voluntary bite force measured by a digital occlusal force gauge (GM10 Nagano Keiki, Japan) between different opponent teeth, employing semi‐hard or soft bite surfaces. A sample of 34 young adults with complete natural dentition was studied. The original semi‐hard bite surface was exchanged by a soft one, made of leather and rubber. Maximum voluntary bite force recordings were made for each tooth group and for both bite surfaces. Statistical analyses (Student's t‐test) revealed significant differences, with higher scores while using the soft surface across sexes and tooth groups (P < 0·05). Differential activation of periodontal mechanoreceptors of a specific tooth group is mainly conditioned by the hardness of the bite surface; a soft surface induces greater activation of elevator musculature, while a hard one induces inhibition more promptly. Thus, soft bite surfaces are recommended for higher reliability in maximum voluntary bite force recordings.     

The craniofacial morphology and maximum bite force in sleep bruxism patients with signs and symptoms of temporomandibular disorders

Objectives:

The purpose of the present study was to compare craniofacial morphology and bite force of bruxist patients with signs and symptoms of temporomandibular disorders.

Method:

Fourteen subjects with sleep bruxism and 14 healthy subjects participated. The signs and symptoms of the temporomandibular disorders were identified according to the Craniomandibular Index (CMI). Maximum bite force was measured using strain-gage transducers. Lateral cephalometric films were taken, and linear and angular measurements were performed.

Results:

Bite force between bruxist and non-bruxist females was not significant, whereas males with bruxism revealed higher bite forces. None of the linear and angular measurements differed significantly between bruxist and non-bruxist males. However, higher mandibular corpus length and anterior cranial base length, and lower gonial angle were observed in bruxist females compared to non-bruxist females. Negative correlation between bite force and CMI values was found in both genders.

Discussion:

Bruxist females had higher CMI values than bruxist males, which could lead to relatively lower bite forces.     

The curve of Spee and craniofacial morphology: a multiple regression analysis

The aim of this study was to investigate the relationship between the curve of Spee and skeletal facial morphology. Dental casts and lateral cephalograms were obtained from 59 orthodontic patients. The amount of concavity of the curve of Spee was calculated by a second-order quadratic interpolation of buccal cusp tips obtained from lateral digital photographs of the teeth. The cephalometric analysis aimed to evaluate the sagittal and vertical craniofacial dimensions as well as the position of the mandibular condyle with respect to the occlusal plane. These variables, included in a multiple regression model, could explain 34% of the total variance of the curve of Spee. The amount of the curvature was significantly related to (a) the horizontal position of the condyle with respect to the dentition, (b) the sagittal position of the mandible with respect to the anterior cranial base, and (c) the ratio between the posterior and anterior facial height. No significant relationship was found between the curve of Spec and any of the other cephalometric variables. The curve of Spee was not influenced by age and gender of the subjects investigated.     

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。     

Reliability of maximum bite force measurements in age-varying populations

Summary  In order for bite forces to be used clinically, they must be reliable. While bite force transducers are accurate and precise during bench tests, widely varying reliabilities of intra-oral bite forces have been reported when measured in human subjects. Because few studies have reported total reliability, the clinical use of intra-oral bite forces measurements remains questionable. The purposes of this study were to (i) estimate total reliability, including both within- and between-session reliabilities, of repeated maximum incisor and molar bite force measurements and (ii) demonstrate how extraneous variation affects reliability by comparing estimates for which the effects of age have and have not been controlled. A sample of 28 healthy subjects with Class I normal occlusion (seven subjects in each of four age groups: 5, 8, 11 and 14 years) performed two sessions approximately 90 min apart. Each session consisted of three maximum voluntary bites at three bite positions (incisor and right and left molars). For each bite position, between-subject variance (true variance), between-session variance and within-session variance were calculated using Multilevel modelling procedures. The variances were used to estimate between-session reliabilities, within-session reliabilities and total reliabilities. Within-session reliabilities were substantially higher than between-session reliabilities, which in turn was higher than total reliabilities at all bite positions. Reliabilities were highest at the incisor bite position. Not controlling for age effects substantially overestimated total reliability at all bite positions. After controlling for age effects, total reliabilities of repeated maximum bite forces were low to moderate.     

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.     

Maximal bite force and its associations with spinal posture and craniofacial morphology in young adults

Maximal bite force (MBF) and its associations with craniofacial morphology and spinal posture were studied in a group of young adults (46 M and 38 F) aged 21 to 23 years. MBF was recorded in molar and incisal regions. Sagittal spinal posture was measured by spinal pantography and trunk asymmetry at thoracic and lumbar levels by a forward-bending test. Craniofacial variables and posture of the cervical spine were examined from lateral cephalograms taken in a natural head position. No statistically significant correlations existed between MBF and spinal posture, but significant correlations did exist between MBF and craniofacial variables, especially in women.     

Maximal bite force and its associations with spinal posture and craniofacial morphology in young adults

Maximal bite force (MBF) and its associations with craniofacial morphology and spinal posture were studied in a group of young adults (46 M and 38 F) aged 21 to 23 years. MBF was recorded in molar and incisal regions. Sagittal spinal posture was measured by spinal pantography and trunk asymmetry at thoracic and lumbar levels by a forward-bending test. Craniofacial variables and posture of the cervical spine were examined from lateral cephalograms taken in a natural head position. No statistically significant correlations existed between MBF and spinal posture, but significant correlations did exist between MBF and craniofacial variables, especially in women.     

Comparison of maximum bite force and dentate status between healthy and frail elderly persons

The purpose of the present study was to (1) determine the standard value of maximum bite force and to (2) compare the maximum bite force of the elderly between healthy and frail subjects. Subjects included 349 healthy elderly individuals (149 males, 200 females) and 24 frail elderly individuals (seven males, 17 females) ranging from 65 to 74 years of age. Maximum bite force was evaluated using a Dental Prescale system. The maximum bite force of the healthy subjects was significantly higher than that of the frail subjects in both males (P=0.020) and females (P=0.015). However, no significant difference was observed in the number of present teeth between the healthy and frail subjects. Median of maximum bite force in healthy males was 408.0 N, and that of the healthy females was 243.5 N. These results suggest that the frail elderly have latent bite force problems.     

头姿势与颅面形态和错(牙合)畸形的关系

头姿势与颅面形态和错(牙合)畸形之间存在着一定的相关性.在颅面的生长发育过程中,一定的头姿势习惯常最终伴有一定形态的颅面结构,同时头姿势是影响错(牙合)畸形的发生、发展以及正畸、正颌治疗后稳定性的重要因素之一.有关头姿势与错(牙合)畸形间关系的研究一直备受正畸界的关注,本文就头姿势与颅颌面形态、头姿势与(牙合)、头姿势...     

儿童下颌偏斜者颌面结构与颈椎姿势相关性研究

目的:研究儿童下颌偏斜病例的颌面结构与颈椎姿势的相关性。方法:对20例儿童下颌偏斜患者拍摄X线头颅定位侧位片,进行头影测量及统计学分析。结果:儿童下颌偏斜患者的颈椎齿突倾斜度、颈椎齿突平面倾斜度、颈椎倾斜度与眶耳平面、腭平面、咬合平面、下颌平面的倾斜度之间均呈正相关;患者第2颈椎到第4颈椎的弯曲度与颈椎齿突倾斜度、颈椎齿突平面倾斜度、颈椎倾斜度及眶耳平面、腭平面、咬合平面、下颌平面的倾斜度之间均呈负相关。结论:儿童下颌偏斜患者的颌面结构与颈椎姿势具有相关性,下颌偏斜应尽早矫治,在矫治颌面畸形的同时还应矫正异常的颈椎姿势。     

In vivo evaluation of occlusalcontact area and maximum bite force in patients with various types of implant-supported prostheses

Abstract

Objective. To determine the effects of various implant retained and/or supported prostheses on number of occlusal contacts (NOC), occlusal contact area (OCA)and maximum bite force (BF). Patients and methods: In total, 56 patients were included in the study; five test groups and two control groups. The patients in the treatment groups received implant-supported/retained prosthesis; over-dentures retained with two individual attachments in occlusion with complete denture, with four individual attachments in occlusion with complete denture, with four individual attachments in occlusion with fixed partial dentures or natural dentition, 6-implant retained fixed bridges in occlusion with natural dentition and 8-implant retained fixed bridges in occlusion with natural dentition. The patients in control group 1 were wearing conventional complete maxillary and mandibular dentures, whereas in control group 2 they had fixed full-arch porcelain-fused to metal restorations prostheses for both arches. Dental Pre-scale was used measure the NOC, BF and OCA. Results. There was no statistically significant difference between the treatment and control groups, among the groups with regards to NOC. OCA demonstrated different results among the removable and fixed reconstruction groups. With regards to BF, removable dentures supported with four implants showed higher bite force values than controls and two implant over-dentures. Also, a fixed reconstruction using eight implants showed higher BF values than a fixed reconstruction using six implants. Conclusion. Use of implants for removable dentures and fixed reconstructions improve occlusal contact area and bite force.     

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.