关于[牙合]与咬合名词定义的商榷

我国口腔医学界广泛应用的“[牙合]”字一直未能列入国家词典。2008年作者在参与全国科学技术名词审定委员会组织编写的《医学美学与美容医学名词》时曾与国家科学技术名词审定委员会的专家进行过讨论[1],当时名词委专家给出的意见是“[牙合]”字的定义不明确,并指出口腔医学专业的解释也不统一,如有认为[牙合]是咬合时上下牙的接触,有认为是静止状况的咬合接触,也有认为[牙合]同咬合[2]。名词委专家建议[牙合]一定要有明确的定义,若相同只能标注同咬合,不宜混淆。[牙合]的定义问题也带来一些临床问题。作者认为对[牙合]与咬合相应的专有名词的定义进行讨论十分必要,特别是确定其明确的定义,有利于口腔医学与社会的学习和交流。根据我们在临床、科研、教学的实践经验,有以下建议供参考:1、“[牙合]”是指上下颌牙接触时的状态,上下颌牙无论在闭合或咀嚼运动过程以及其它运动形式时上下颌牙实际达到接触时的关系。     

Relationship between pattern of masticatory path and state of lateral occlusal contact

Summary  The purpose of this study is to clarify whether the state of occlusal contact on lateral excursion is related to the pattern of masticatory movement path. The masticatory movement during mastication of softened chewing gum and the occlusal contact on lateral sliding of the mandible by 1 mm (L1), 2 mm (L2) and 3 mm (L3) were recorded in 50 healthy subjects. The path of masticatory movement was classified into one of seven patterns. The number of teeth involved in the occlusal contact in each pattern was investigated and compared among different lateral occlusal positions. The occlusal contact was then classified into 15 types based on one or a combination of the following four regions; incisal region, canine region, premolar region and molar region. The number of occlusal contact type for each pattern was investigated and compared among patterns. The number of teeth involved in occlusal contact decreased as the degree of lateral excursion increased, and significant differences were observed among the lateral occlusal positions ( P  < 0·001). The occlusal contact tended to decrease in the molar region and increase in the canine or premolar regions as the degree of the lateral excursion increased. When comparing among patterns, significant differences were observed at L2 and L3 (L2; P  < 0·001, L3; P  = 0·030) but not at L1 ( P  = 0·318). The difference was remarkable at L2. It was suggested that the state of occlusal contact at L2 and L3, particularly at L2 was related to the masticatory path pattern.     

A survey on the potential relationships between TMD,possible sleep bruxism,unilateral chewing,and occlusal factors in Turkish university students

Objective: To evaluate whether there is a relationship between possible sleep bruxism (PSB), temporomandibular disorders (TMD), unilateral chewing (UC), and occlusal factors in university students recruited from Cumhuriyet University in Turkey.

Methods: For this cross-sectional survey, 519 (223 males, mean age 21.57 ± 2.3 years, 296 females, mean age 21.02 ± 2 years) university students who admitted to the Department of Oral and Maxillofacial Radiology of the Faculty of Dentistry, Cumhuriyet University for dental care between 2012 and 2014 were selected randomly. Students were asked to complete a questionnaire form including questions about TMD, PSB and UC. Presence and direction of malocclusion were recorded during clinical examination. Chi-square test was used for statistical analysis.

Results: It was found that 96.6% of the students with PSB had TMD (p < 0.05). The prevalence of severe TMD was high among students with PSB. There was a significant association between UC, PSB and TMD (p < 0.05). No statistically significant association was found between occlusal factors and PSB and TMD (p > 0.05).

Conclusion: Sleep bruxism, which heavily depends on self-report, is significantly associated with TMD. Unilateral chewing seems to be a common factor for development of SB and TMD. However, further studies are needed to corroborate this finding. Additionally, this study supports the hypothesis that occlusal factors are not related to self-reported sleep bruxism.     

Effects of chewing exercises on the occlusal force and masseter muscle thickness in community-dwelling Koreans aged 65 years and older: A randomised assessor-blind trial

Chewing exercises have been applied in clinical settings to improve the occlusal force and function of the masseter muscle in elderly individuals. However, the clinical relevance and effects of chewing exercises are unclear. This study aimed to investigate the effects of bilateral chewing exercises on the occlusal force and masseter muscle thickness in community-dwelling Koreans aged 65 years. Forty community-dwelling healthy elderly individuals were enrolled in this study. They were assigned to the experimental or the control group. The experimental group performed chewing exercises using medical equipment developed to facilitate such exercises. The chewing exercises were divided into isometric and isotonic types and were performed for 20 min/d, 5 days/wk, for 6 weeks. The control group did not perform any chewing exercises. The outcome measures were occlusal force and masseter muscle thickness, which were evaluated using an occlusometer and ultrasound device, respectively. A paired t test and an independent t test were used to evaluate the training effects. Within-group comparisons showed that occlusal force and masseter muscle thickness improved significantly in the experimental group (P < .001 for both), while the control group showed no significant improvements (P = .098 and .130). Between-group comparisons showed that the experimental group had a greater increase in occlusal force and masseter muscle thickness (P < .05 for both) compared to the control group. These results suggest that chewing exercises are effective in improving occlusal force and masseter muscle thickness in healthy elderly individuals.     

Bilateral balanced occlusion compared to other occlusal schemes in complete dentures: A systematic review

No consensus has been reached regarding the best occlusal scheme for making complete dentures. Thus, the purpose of this systematic review was to compare bilateral balanced occlusion (BBO ) with other occlusal schemes (canine guidance, lingualised occlusion and zero degree) in complete dentures. The schemes were compared in terms of quality of life/satisfaction and masticatory performance. Two independent reviewers performed a comprehensive search of studies published in or before October 2017 using the PubMed/MEDLINE , Scopus and Cochrane Library databases. The search was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA ) statement. The focused question was: “In conventional complete denture, is BBO better than lingualised occlusion, canine guidance and zero degree in terms of quality of life, patient satisfaction and masticatory performance/muscle activity?” Seventeen studies were selected for analysis. In total, there were 492 patients with a mean age of 64.78 years and a mean follow‐up duration of 2.96 months (range: 1‐6 months). All studies compared BBO with the other occlusal schemes. Eleven studies evaluated the influence of the occlusal scheme designs on quality of life and satisfaction, and 8 studies evaluated masticatory performance and muscle activity between BBO and the other occlusion schemes. The present systematic review indicated that BBO does not confer better quality of life/satisfaction or masticatory performance and muscle activity. Thus, lingualised occlusion can be considered a predictable occlusal scheme for complete dentures in terms of quality of life/satisfaction and masticatory performance, while canine guidance can be used to reduce muscular activity.     

Biomechanics of occlusion – implications for oral rehabilitation

The dental occlusion is an important aspect of clinical dentistry; there are diverse functional demands ranging from highly precise tooth contacts to large crushing forces. Further, there are dogmatic, passionate and often diverging views on the relationship between the dental occlusion and various diseases and disorders including temporomandibular disorders, non‐carious cervical lesions and tooth movement. This study provides an overview of the biomechanics of the masticatory system in the context of the dental occlusion's role in function. It explores the adaptation and precision of dental occlusion, its role in bite force, jaw movement, masticatory performance and its influence on the oro‐facial musculoskeletal system. Biomechanics helps us better understand the structure and function of biological systems and consequently an understanding of the forces on, and displacements of, the dental occlusion. Biomechanics provides insight into the relationships between the dentition, jaws, temporomandibular joints, and muscles. Direct measurements of tooth contacts and forces are difficult, and biomechanical models have been developed to better understand the relationship between the occlusion and function. Importantly, biomechanical research will provide knowledge to help correct clinical misperceptions and inform better patient care. The masticatory system demonstrates a remarkable ability to adapt to a changing biomechanical environment and changes to the dental occlusion or other components of the musculoskeletal system tend to be well tolerated.     

青少年错(牙合)患者正畸治疗后动态(牙合)接触特征变化初探

目的 探讨经正畸治疗后获得正常牙列形态的青少年错(牙合)患者矫治结束后12个月内动态(牙合)接触的变化规律,以期为正畸矫治结束前的精细调整提供参考.方法 选择20例正畸矫治后戴用标准霍利保持器的青少年患者,并将20例患者分为(牙合)干扰组与无(牙合)干扰组,其中(牙合)干扰组患者11例,无(牙合)干扰组9例,使用T-ScanⅡ咬合分析系统分别于矫治结束即刻(T1)和矫治结束12个月(T2)时检查患者的动态(牙合)接触,对比分析两个时间点总体与分组情况下患者动态(牙合)接触特征.结果 20例患者的总体情况:T1至T2的前伸、左侧方和右侧方(牙合)分离时间明显减少,从(1.07±0.87)、(0.91±0.47)、(0.76±0.43)s分别降至(0.43±0.25)、(0.67±0.41)、(0.50±0.27)s,两时间点差异均有统计学意义(P＜0.05).其中4例存在(牙合)干扰的患者(牙合)干扰消失.1例出现(牙合)干扰侧咀嚼肌不适症状.无(牙合)干扰组T1至T2的前伸、左侧方和右侧方(牙合)分离时间明显减少,从(1.25±1.11)、(0.84±0.15)、(0.52±0.49)s降至(0.35±0.15)、(0.36±0.15)、(0.33±0.11)s,两时间点差异均有统计学意义(P＜0.05),(牙合)干扰组T1与T2的前伸、左侧方和右侧方(牙合)分离时间的差异无统计学意义(P＞0.05).结论 戴用标准霍利保持器12个月后患者的动态(牙合)接触总体改善,但(牙合)干扰的存在影响了咬合的自行改善进程,矫治器拆除前对动态抬(牙合)接触的评估与精细调整仍是必要的.     

Masticatory jaw movement optimization after introduction of occlusal interference

Summary How ‘control’ characteristics of masticatory jaw movement, such as skilfulness of the movement, change after alteration in occlusion remains uncertain. For each of 10 healthy adults with good occlusion, an occlusal interference with artificial ‘tooth‐cusp’ was introduced to the crown of the upper molar tooth on the non‐working side of unilateral chewing. Mandibular incisor‐point movements were then recorded by a 3D tracking device. The introduction of the occlusal interference induced a remarkable increase in the normalized jerk‐cost (NJC), prolonged duration of the decelerative phase and lowered peak velocity for jaw closing movement during chewing. Overall, the NJC and velocity profile showed significant recoveries during the course of about 90 repetitive chewing cycles performed under the altered occlusal condition. These findings suggest that acute adaptive changes of jaw motion after introduction of occlusal interference might be characterized as the recovery process of movement skilfulness in terms of movement smoothness and velocity profile.     

颞下颌关节紊乱病患者正畸治疗前后骀接触点及[牙合]力变化的研究

目的利用电子咬合记录仪（TScan）研究颞下颌关节紊乱病（temporomandibulardisorders,TMD）患者正畸治疗前后,咬合接触的变化,从而评价正畸治疗前后各咬合指标的改善程度及T-scan电子咬合记录仪用于咬合研究的意义。方法经关节门诊确诊为TMD病例13例,男4例,女9例,年龄13~37岁,针对不同患者TMD情况,为每例病人制定个性化矫治方法及目标。治疗前后采用美国Tekscan公司的T-scan咬合记录仪,分别记录[牙合]力中心在前后向与左右向的位移,[牙合]力不对称指数,[牙合]接触点,[牙合]接触面积及咬合时间。记录结果从T-scansoftware4．02存贮并输出。结果TMD患者在正畸治疗后临床症状得到缓解,临床检查无疼痛、开口受限;5例弹响消失,7例有单侧轻度开口初、中期弹响,1例有双侧开口初弹响。主观上8例明显自觉咬合舒适程度明显改善。T-scan检查可见咬[牙合]力中心位移在前后向及左右向位移均减小（P〈0．05）,袷[牙合]布分更接近中心（Pdo．05）,治疗前后差异有显著统计学意义,治疗前后骀力不对称性有明显改善（P〈0．05）;但咬合接触点及接触面积在治疗前后差异无统计学差异。所有病例咬合时间治疗后较治疗前减小,但结果没有统计学差异。结论TMD患者的[牙合]治疗应针对患者个性处理,[牙合]力分布及咬合中心点可以作为TMD正畸治疗前后的评价指标。     

Electromyographic assessment of jaw muscles in patients with All‐on‐Four fixed implant‐supported prostheses

This study evaluated the electromyographic (EMG) characteristics of masticatory muscles in patients with fixed implant‐supported prostheses according to All‐on‐Four^® principles and in control healthy dentate subjects. Twenty‐six subjects aged 50–74 years were examined. Eighteen were edentulous and had been successfully rehabilitated with (i) mandibular All‐on‐Four^® implant‐supported fixed prostheses and maxillary complete dentures (10 patients) and (ii) mandibular and maxillary All‐on‐Four^® implant‐supported fixed prostheses (eight patients). Eight reference subjects had natural dentition. Surface EMG recordings of the masseter and temporalis muscles were performed during maximum voluntary teeth clenching and during unilateral gum chewing. All values were standardised as percentage of a maximum clenching on cotton rolls. During clenching, a good global neuromuscular equilibrium was found in all participants. During chewing, all groups had similar values of working‐side muscle activities and of chewing frequency. No significant differences in the analysed EMG parameters were found between the patients with mandibular and maxillary All‐on‐Four^® implant‐supported prostheses and the reference subjects. In contrast, standardised pooled muscle activities and standardised muscular activities per cycle were larger in patients with a maxillary removable prosthesis than in control subjects (Kruskal–Wallis test, P < 0·01). Also, patients wearing a complete maxillary denture showed a poor neuromuscular coordination with altered muscular pattern and lower values of the index of masticatory symmetry than dentate control subjects (P < 0·01). EMG outcomes suggest that All‐on‐Four^® implant‐supported prostheses may be considered a functionally efficient treatment option for the rehabilitation of edentulous patients with reduced residual bone volume.     

Association between masticatory performance using a colour-changeable chewing gum and jaw movement

The purpose of this study was to investigate the relationship between masticatory performance as determined using a colour-changeable chewing gum and mandibular movements. Subjects comprised 45 fully dentate adults (23 men, 22 women; mean age, 28·1 years). The gum was chewed for a specified number of chewing strokes (20, 40, 60, 80, 120 or 160 strokes) without any instructions as to chewing side. A colourimeter was used to measure L*, a* and b* values (CIE-L*a*b* colour system) for the chewed gum, then the difference between two colours in the CIE-L*a*b* colour space (ΔE) for each number of chewing strokes was calculated according to a formula. Index of masticatory performance (ΔE60) for each subject was obtained using ΔE for 20, 40, 60, 80, 120 and 160 strokes. Mandibular movements were recorded using an opto-electric system with six degrees of freedom. Twelve parameters of mandibular movements relating to amplitude, duration, velocity and angle were computed for each cycle, and mean values for 10 cycles (from cycle 11 to 20) were calculated separately. Stepwise multiple regression analysis identified maximum closing velocity and closing angle as predictors accounting for 18% of the variation in ΔE60. These results suggest that lower angles of approach to intercuspation and faster speed during closing duration are associated with colour changes in the colour-changeable chewing gum.     

单侧咬合接触对咬肌和颞肌正中咬合最大紧咬电位的影响

目的 :检测单侧咬合接触状态下最大紧咬时 ,双侧咬肌和颞肌前束的电位活动 ,探讨此二肌的功能特点。方法 :9名正常男性大学生 ,采用EM2型肌电仪检测自然状态下正中最大紧咬和单侧咬合接触 (一侧咬棉条 ,另一侧咬合不接触 )状态下正中最大紧咬时 ,双侧咬肌和颞肌前束的电位。结果 :自然状态下正中最大紧咬时 ,双侧颞肌前束肌、双侧咬肌肌电值均无显著差异 (P >0 0 5 ) ;单侧咬合接触正中最大紧咬时 ,咬合接触对侧颞肌前束肌电值明显降低 (P <0 0 5 ) ,咬肌肌电值无明显变化 (P >0 0 5 )。结论 :正中咬合时 ,是否有咬合接触关系对颞肌前束的肌电活动有明显影响 ,而对咬肌的肌电活动无明显影响。     

A factor analysis of traits as measured by COCSTOC-MOT to identify occlusal trait combinations.

Occlusal conditions which vary significantly from accepted social norms for dental appearance may socially handicap an individual. An instrument is required by which socially unacceptable occlusal conditions can be identified by members of the public who have internalized society's norms for acceptable dental appearance. The factors identified in this paper make it possible to select a reasonable number (100) of models for constructing a measurement instrument which depicts the full range of occlusal patterns found in a natural population for use in assessing the social acceptability of occlusal conditions. This paper presents the methodology and process used to identify individual occlusal traits which tend to occur together in trait combinations or independently and their range from "normal" to extreme. Data on the frequency distribution of the individual COCSTOC measurements found in a natural population was subjected to a factor analysis which identified 18 occlusal patterns (combinations of traits) and five unique or independent traits or anomalies.     

Test–retest reliability of quantitative sensory testing for mechanical somatosensory and pain modulation assessment of masticatory structures

Assessing the reliability of medical measurements is a crucial step towards the elaboration of an applicable clinical instrument. There are few studies that evaluate the reliability of somatosensory assessment and pain modulation of masticatory structures. This study estimated the test–retest reliability, that is over time, of the mechanical somatosensory assessment of anterior temporalis, masseter and temporomandibular joint (TMJ) and the conditioned pain modulation (CPM) using the anterior temporalis as the test site. Twenty healthy women were evaluated in two sessions (1 week apart) by the same examiner. Mechanical detection threshold (MDT), mechanical pain threshold (MPT), wind‐up ratio (WUR) and pressure pain threshold (PPT) were assessed on the skin overlying the anterior temporalis, masseter and TMJ of the dominant side. CPM was tested by comparing PPT before and during the hand immersion in a hot water bath. anova and intra‐class correlation coefficients (ICCs) were applied to the data (α = 5%). The overall ICCs showed acceptable values for the test–retest reliability of mechanical somatosensory assessment of masticatory structures. The ICC values of 75% of all quantitative sensory measurements were considered fair to excellent (fair = 8·4%, good = 33·3% and excellent = 33·3%). However, the CPM paradigm presented poor reliability (ICC = 0·25). The mechanical somatosensory assessment of the masticatory structures, but not the proposed CPM protocol, can be considered sufficiently reliable over time to evaluate the trigeminal sensory function.     

根管治疗后(牙合)面单面缺损双尖牙修复方式的生物力学研究

目的：从生物力学角度比较不同方法修复根管治疗后双尖牙的效果，并探询最佳方案。方法：实验通过收集对称的双尖牙，对照组为完整离体牙，试验组制备根管治疗及殆面单面缺损模型，试验一采用银汞充填；试验二采用高强度粘结性材料FX-Ⅱ充填；试验三为银汞充填后再加冠修复；1mm／min加载于与牙体长轴成45。烦尖舌斜面巾点测试破坏载荷，用SPSS10．0软件包进行配对分析。结果：试验一、试验二P〈0．05，充填组破坏载荷低于对照组；试验三P〈O．05全冠组破坏载荷高于对照组。结论：可认为从生物力学角度来讲，骀面单面缺损的最佳修复方法是全冠修复。