Laboratory comparison of three occlusal registration methods for identification of induced interceptive contacts

This study compared the performance of a new computerized occlusal analysis (T-Scan) system with that of Accufilm and Shimstock foil for the registration of tooth contacts on a laboratory model. Induced interceptive contacts were created on epoxy models in a mechanical closing device and the occlusal contacts were recorded for each registration method. The traditional methods were similar to the computerized analysis but the T-Scan system provided additional differential diagnostic information in force and time modes for an improved occlusal analysis.     

Evaluation of occlusal contacts in maximum intercuspation using the T-Scan system

summary Different authors have questioned the reliability of the T-Scan system as a method for registering occlusal contacts. The number of tooth contacts resulting from four bites made in maximum intercuspation was analysed with T-Scan using time moment statistics. The results indicate that (1) the largest number of contacts occur in the molar region (2) variability between subjects is greater than variability within subjects, and (3) it is possible to identify the subject being tested in 90.3% of cases. The T-Scan system has proved to be a reliable method for the analysis and evaluation of occlusal contact distribution in maximum intercuspation.     

T-ScanⅡ咬合分析数据作为早期牙隐裂调(牙合)干预指标的应用研究

目的:探讨牙隐裂(cracked tooth syndrome,CTS)患者动态咬合特征,分析其异常(牙合)因素,探索T-Scan Ⅱ咬合力分析系统作为牙隐裂调(牙合)干预指标之一的可行性.方法:T-ScanⅡ咬合力分析系统记录15名早期牙隐裂患者调胎干预前后牙尖交错位(ICP)及左右侧方咬合的过程.定量测定(牙合)接...     

Customized procedure to display T-Scan occlusal contacts

The virtual technique described in this article integrates reverse engineering and mandibular dynamics into dental computer-aided design and computer-aided manufacturing (CAD-CAM) systems. This technique aims to provide more objective information to the dental technician for the diagnosis, planning, and treatment phases. In order to carry out this protocol, the following devices, currently available in many practices, are necessary: an intraoral scanner, a T-Scan system, and some specific open reverse engineering software. By means of a virtual procedure, the T-Scan system detects the occlusal contacts, and the occlusal surfaces are obtained using an intraoral scanner. Once the alignment between the 3-dimensional occlusal surface and the T-Scan registration is carried out, the resulting contacts are projected onto the patient’s occlusal surfaces; in this way, occlusal forces are obtained over time. The results obtained with this procedure demonstrate the feasibility of integrating different tools and software and the full integration of this procedure into a dental digital workflow.     

Clinical application of T-scan System. 1. Sensitivity and reproducibility and its application

Analyzing occlusal contacts is significant for establishing the occlusal scheme as well as for the diagnosis on dysfunction of stomatognathic system. We tested a new occlusal contact analyzing device (T-Scan: Tekscan Inc. Boston, U.S.A.) for its sensitivity and reproducibility in relation to its clinical application. Following results were obtained. 1) As the modeling of dental arch of this system was not always correct, much care should be needed for identifying the contact location. 2) The minimum amount of load needed for displaying each five step occlusal force increased linear fashion (step 1: 250 g and step 5: 1750 g) when the sensor was vertically pressed on the intersection of force sensitive line. The minimum amount of force changed with the loading condition such as area and direction. Distortion of the sensor could lead the measurement error. 3) Since the time measurement data by this system were shorter than actual length of time and were measured over about 250 g load, light and early occlusal contacts could not be detected.     

A clinical application of the T-Scan II system--usefulness for evaluating occlusal contacts of complete denture wearers

The purpose of this study was to assess the reproducibility of the T-Scan II system and its clinical usefulness for evaluating occlusal contacts of complete denture wearers. The occlusal contacts of 13 dentate subjects, and 14 complete denture wearers, were recorded using a T-Scan II system during maximum voluntary clenching. The recordings for complete denture wearers were taken after each treatment for the new denture, and continued until the completion of all corrections. The recordings for complete denture wearers were analyzed using repeated measured ANOVA. In addition, the variables obtained with the system, the delta of the occlusal area and load, and the maximum-load time (MLT), which represented the time length taken to reach the occlusal load at the maximum level, were then compared between dentate subjects and complete denture wearers, using a t-test. The conclusions were as follows: 1. The standard errors values for both occlusal area and the load recordings for the dentate subjects were limited to within 10% of the means. 2. The values of the occlusal area and load significantly increased, and delta of the occlusal area and load significantly decreased, as the denture corrections were repeated. 3. The means of the MLT were about 0.3 seconds for dentate subjects, and 0.8 seconds for complete denture subjects. It was revealed that the T-Scan II showed acceptable reproducibility, and it was useful to evaluate occlusal contacts of complete denture wearers.     

全口义齿咬合接触的三维测量分析

目的采用三维数字化方法对咬合接触参数进行测量分析。方法应用非接触式激光三维扫描和三维数字化技术,在三维扫描和重建10副全口义齿人工牙面以及正中时咬合状态的基础上,测定咬合接触的数目和部位,并与T-Scan咬合仪的测量结果进行配对t检验。结果⑴咬合接触参数的测量结果显示,咬合接触区域主要集中在磨牙和前磨牙区;⑵应用激光扫描系统测量和T-Scan系统测量的咬合接触部位和数目比较,P>0.05,在统计学上无显著性差异。结论本研究将激光扫描技术引入全口义齿咬合接触研究领域,通过测量全口义齿咬合接触部位和数目,并与T-Scan系统的测量结果进行比较,进一步验证了该方法进行咬合检测的可靠性,为今后咬合接触的研究提供了新的思路。     

In vitro study on accuracy and repeatability of the T-Scan II system

The T-Scan system has been used to analyze the distribution of occlusal loading forces, and occlusal contact variability. An enhanced version, the T-Scan II system, has been developed with clinical significance of its center of force. The T-Scan II system was also found to be clinically useful for measuring simultaneous occlusal contacts bilaterally. However, its improvement in accuracy and repeatability is still unknown. In the present study, the accuracy of time recordings, the liner relation between loaded forces and force recordings, the pressure sensitivity, and the variability of force recordings for repeated loadings, were investigated. The conclusions were as follows: 1. By regression analysis between the time and the time recording, the following equation was obtained: Y = 0.00357 + 0.9889 X R2 = 0.9964. The time recordings were proportion to the real time. 2. The force recordings were acceptably precise, especially for the moderately high level and default level, where a linear relation was observed. 3. The pressure sensitivity showed 6-61 g/cm2 for the high-4 level, 25-581 g/cm2 for the moderate-3 level, 56-1814 g/cm2 for the default level, and 146-3821 g/cm2 for the low-2 level. 4. The stability of force recordings for the repeated loadings was acceptable. A significant influence of repeated loading was found for the low-2 level; however, no significant difference was found between the repeated loadings, by post hoc analysis. On the contrary, the repetition of continuous loadings raised force recordings gradually, up to 120% at the fourth loading. The level of the force recordings stayed at the same level with no significant influence by repetition.     

Stable tooth contacts in intercuspal occlusion makes for utilities of the jaw elevators during maximal voluntary clenching

Data are inconsistent concerning whether the level of the surface electromyographic (SEMG) activity of jaw‐closing muscles increases when biting forces elevated during maximal voluntary clenching (MVC). In this study, T‐Scan III system and BioEMG III system were used to record bite force, occlusal contacts and SEMG activity of the anterior temporalis (TA) and of the masseter muscles (MM) simultaneously. Recordings were obtained from 16 healthy young adult males during different conditions: (i) a fast MVC from resting position to intercuspal position (ICP); (ii) mandibular movements from ICP to protrusive or lateral edge‐to‐edge positions with teeth in contact with biting; (iii) a fast MVC in protrusive and lateral edge‐to‐edge positions. A higher level of SEMG activity was associated with a higher bite force during occluding movements (P < 0·05). However, during fast MVC from rest to ICP, the largest number of occlusal contacts was achieved and distributed more symmetrically, the highest level of biting force was obtained, but the SEMG activity of the jaw elevator muscles was reduced compared with its maximum level (P < 0·05). This phenomenon was not observed during the fast MVC in protrusive or lateral edge‐to‐edge positions. The present results that a lower SEMG activity was associated with the largest number of occlusal contacts and the highest level of bite force during centric MVC demonstrated a complex integration of jaw‐closing muscles when a stable occlusion is present.     

正常(牙合)牙尖交错位咬合平衡的定量研究

目的　对正常（牙合）牙尖交错位（ICP）最大（牙合）力咬合进行定量研究，初步探讨ICP咬合平衡的生理范围。方法　应用T－Scan　Ⅱ系统记录123名正常骀者ICP最大（牙合）力的咬合情况，测量并计算力的中心点（COF）、（牙合）力百分比值、胎接触点数目。结果　正常胎者ICP最大（牙合）力时力的中心点相对位置、（牙合）力百分比差值以及不对称系数均服从正态分布，95％参考值范围分别为：－6．60～6．68mm，－15．50％～12．10％，0．65～1．39；98．4％的正常（牙合）者ICP最大（牙合）力咬合时力的中心点分布于后牙区。结论　正常（牙合）者最大（牙合）力时ICP咬合是稳定、平衡的咬合。     

计算机辅助分析全口义齿咬合特征

目的本文通过计算机辅助咬合分析的方法,观察全口义齿修复后的咬合接触特征,定量研究咬合接触分布的变化。方法戴用3个月及30个月的全口义齿修复患者各14例。采用T-ScanII咬合分析仪进行体内咬合分布特征及咬合时间的测定。记录全121义齿左右侧咬合面积不对称指数,咬合力中心值,咬合力前后向分布比率,咬合时间,最大负载时间。结果戴用全口义齿30个月的患者,咬合面积不对称指数、咬合时间及最大负载时间略有缩短,咬合力中心略有前移,但2组间无统计学差异。结论全口义齿戴用30个月后,患者对全口义齿有较好的适应能力,咬合平衡性稳定提高。     

T-Scan �����ֻ�ҧ�Ϸ���ϵͳ�ٴ�Ӧ�ý�չ

T-Scan Ⅲ数字化咬合分析系统是最新的专门用来精确记录和分析咬合力随接触时间变化的工具。目前,在咬合生理研究、种植义齿、修复治疗、颞下颌关节病治疗、正畸治疗等临床领域得到广泛应用。本文对T-Scan Ⅲ数字化咬合分析系统的发展、优点及临床最新应用进展做一综述。     

正常牙尖交错位咬合的T-Scan Ⅱ系统分析

目的:观察正常人群从下颌姿势位向牙尖交错位闭合时咬合接触的情况及其与时间的关系。方法:利用T-Scan Ⅱ扫描系统对30位咬合关系正常,没有肌功能紊乱和颞下颌关节紊乱病的受试者进行咬合检查,记录其咬合力分布情况、咬合接触时间。采用SAS 9.0软件包对数据进行统计学分析。结果:受试者在牙尖交错位状态下记录的两侧咬合力量分布无显著性差异(P=0.3242);受试者牙尖交错位时的咬合力占累积最大力的百分比平均为96.89%,可信区间为90.88%~100%;平均咬合接触时间为(0.2015±0.086)s,两者无相关性(P>0.05)。结论:咬合力中心的位置、牙尖交错位时的咬合力与累积最大力的差值、咬合接触时间均可作为临床上判断咬合是否健康的指标,亦可应用于咬合治疗疗效的评判。     

青少年错患者正畸治疗后牙尖交错位接触特征变化初探

目的探讨经正畸治疗获得正常牙列形态的青少年错患者主动矫治结束后12个月内牙尖交错位接触的变化规律。方法选择20例正畸主动矫治结束后戴用标准霍利保持器的青少年错患者,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个月时（T2）记录其牙尖交错位接触并进行比较。结果 20例患者T1至T2前牙接触面积及前牙力占总力的百分比有所减小,后牙接触面积及后牙力占总力百分比有所增加,但所有测量项目两时间点的差异均无统计学意义（P〉0.05）。结论戴用标准霍利保持器12个月后,患者牙尖交错位接触状况仅有轻微改善,主动矫治结束前的咬合检查及精细调整是必不可少的。     

Computerized occlusal verification in denture frames

Partial removable prosthesis must foresee masticatory force distribution on all dental arch, with occlusal contacts uniformly distributed on natural and artificial teeth. These dental contacts must have the same intensity and they must happen in the same time, rispetting the gnathology laws. In this work it is investigated the possible utilization in partial removable prosthesis of T-Scan.     

Distribution of occlusal contacts in maximum intercuspation

This study describes the use of the T-Scan system to record and analyze tooth contact data by calculating time moment statistics in the sagittal and transverse axes of the occlusal plane and reports the results of this method to analyze the occlusion of 93 normal subjects. Results confirm the findings of previous investigators and indicate that in a normal dentition there is a tendency for bilateral equality of the tooth contacts about the sagittal axis and that the center of effort for tooth contacts anteroposteriorly is located in the region of the first molar and is symmetrical bilaterally. Because of the rapid and accurate ability of the T-Scan system to identify the distribution of the tooth contacts, it shows great promise as a clinical diagnostic screening device for occlusion.     

青少年错(牙合)畸形正畸后牙尖交错位(牙合)接触特征初探

目的 通过了解青少年错(牙合)畸形正畸后牙尖交错位的(牙合)接触特征,从功能角度对正畸效果进行评价.方法 选择14例经正畸治疗获得正常牙列形态的青少年错(牙合)畸形患者作为病例组,17名性别、年龄与病例组匹配的正常(牙合)健康人作为健康对照组,使用T-ScanⅡ咬合分析系统记录两组牙尖交错位的(牙合)接触特征并进行比较.结果 在1/10、1/4、1/2、3/4最大(牙合)力页面及最大(牙合)力页面上病例组前牙(牙合)接触点数目的 中位数(四分位数间距)分别为1.5(1.0)、3.0(1.3)、4.5(3.3)、5.5(3.0)及5.5(3.3)个,显著大于健康对照组[分别为0.0(0.3)、0.0(0.6)、0.3(0.5)、0.3(1.0)及0.0(1.8)个,P＜0.05];各页面上病例组后牙(牙合)接触面积与健康对照组的差异无统计学意义(P＞0.05);与健康对照组相比,病例组(牙合)力中心点明显偏近中.病例组牙尖交错位建(牙合)时间的中位数(四分位数间距)为0.192(0.141)s,略大于健康对照组[0.163(0.200)s],但两组差异无统计学意义(P＞0.05).结论 与正常猞健康人相比,青少年错(牙合)畸形患者正畸后其前牙承受(牙合)力明显偏大.     

侧方咬合运动中接触型及其分布特征

目的观察侧方咬合运动中接触点的分布特征,并对尖牙尖对尖颌位时的侧方型进行分类。方法利用T-ScanII咬合分析系统记录85名个别正常者侧方咬合运动过程中的接触信息,并进行统计分析。结果尖牙尖对尖颌位时的接触形式有六类:尖牙保护(44.1%)、组牙功能(20.6%)、工作侧多组前牙接触(2.9%)、仅工作侧第一前磨牙接触(8.8%)、工作侧前后牙同时存在接触(20.0%)、工作侧非工作侧同时存在接触(3.5%)。结论自然牙列侧方接触形式除尖牙保护与组牙功能外还存在其它一些型。     

Muscular activity disorders in relation to intentional occlusal interferences

The electromyographic activity (EMG) of the anterior temporal (AT), masseter (M), trapezius (T) muscles and anterior aspect of the digastric (D) was measured in 50 subjects, during six seconds of maximum contraction, bilaterally with and without unilateral premature contacts and individually for each tooth. Special occlusal interferences were designed to assess muscular activity. Muscular activity was measured simultaneously by placing premature contacts on each tooth, under T-Scan monitoring. Premature contacts reduced EMG activity during maximum contraction of the AT, D and M muscles, the highest disruption is in the AT muscle, at the level of upper right 2nd molar, with a 56% reduction in activity. Conversely, there was an increase of activity of the T muscle in all teeth when placing artificial occlusal premature contacts, with the highest difference in the upper right 1st bicuspid. Therefore, occlusal interferences can cause neuromuscular disruptions, thus inducing important muscular discrepancy. Both the EMG and T-Scan monitoring can be considered suitable methods to use in daily dental practice to identify premature contacts and to measure EMG activity.