种植义齿邻接触丧失的研究现状

随着种植义齿越来越多地应用于治疗牙列缺损,许多研究者发现种植戴冠后种植义齿与相邻天然牙之间逐渐发生了邻接触变松或丧失,邻接触丧失导致的食物嵌塞是种植修复的主要并发症之一。国内外学者对种植义齿邻接触丧失的发生率、发生原因以及治疗措施进行了深入研究,本文对相关研究结果进行总结。     

The effect of occlusal contacts on adjacent tooth

PURPOSE: The purpose of this study was to clarify the influence of changes of occlusal contacts on adjacent tooth displacement during articulation. MATERIALS AND METHODS: The amount and direction of displacement of the maxillary left first molar and adjacent teeth were measured using a displacement transducer, Type M-3. Seven subjects were included in this study. On the maxillary left first molar, 8 experimental occlusal contact points were established using platinum foil and these were divided into 2 groups, the buccal and lingual groups, which corresponded to the buccal and lingual cusps, respectively. RESULTS: During clenching, the buccal group showed differences in the direction of the tooth displacement paths among the 3 teeth (second premolar, first and second molar), but there was no difference in the lingual group and the direction of displacement of these 3 teeth was similar to the natural teeth. CONCLUSION: It is necessary to make at least one lingual occlusal contact point to obtain displacement of not only the abutment tooth but also the adjacent teeth.     

Influence of occlusal contacts on tooth displacement

During function, the tooth displacement path depends on occlusal contacts of the upper and lower teeth. Therefore, we must reconstruct occlusal relation carefully so as not to disturb physiological tooth displacement. In this investigation, tooth displacements were measured with the Displacement Transducer type M-3 in varying occlusal contact. The following conclusions were obtained. 1. The location of occlusal contacts influenced the tooth displacement of the upper first molar. Especially, an occlusal contact on the lingual inclination of the lingual cusp, buccal cusp had great influence. The tooth showed displacement toward the buccal direction, and it differed from the physiological tooth displacement path during clenching at the intercuspal position. 2. The location of occlusal contacts had little influence on the tooth displacement of the lower first molar. The tooth showed displacement toward the lingual direction. It was similar to the physiological tooth displacement. 3. On the upper first molar, the location of occlusal force influenced the Stress-Strain curve. Especially, the occlusal force on the buccal cusp had great influence on the amount of tooth displacement. 4. On the lower first molar, the location of occlusal force influenced the Stress-Strain curve. Especially, the occlusal force on the lingual cusp brought much displacement and a 2-phase displacement path, at times. Therefore, occlusal contacts have close relation to tooth displacement, and any occlusal reconstruction should harmonize with tooth displacement representing periodontal tissue distortion.     

Influence of variation in anteroposterior occlusal contacts on electromyographic activity

A full upper stabilization splint divided into three pairs of occlusal bilateral blocks was made for eight healthy young adult subjects. The three pairs of blocks allowed the location of the centric occlusal contacts to vary and to be distributed over equivalent periodontal surfaces. The electromyographic activity of the masseter and temporal muscles was recorded with surface electrodes during maximum voluntary clenching over the centric occlusal blocks. The electromyographic activity from the elevator muscles with the anterior blocks was significantly less than with the intermediate and posterior occlusal blocks. With use of the intermediate blocks, the activity from the elevator muscles was significantly less than with the posterior blocks. The elevator activity with the posterior blocks was similar to that with the full coverage splint.     

Influence of occlusal contacts on tooth displacement for mesio-distal direction

To fabricate a prosthesis which is functionally harmonized with the stomatognathic system, the interocclusal relationship must be reproduced as accurately as possible. This study investigated the influence of the occlusal contacts upon tooth displacement and clarified the optimal occlusal contacts for the prosthesis. The displacement paths of six maxillary left first molars of six adults in good general health were measured in this study. We gave each test tooth eight patterns of artificial occlusal contacts by attaching platinum foil on the occlusal surface. Subjects were asked to perform clenching at the intercuspal position (= ICP) with medium occlusal forces, and 3-dimensional tooth displacement paths were measured by the Type M-3 tooth displacement transducer. The following conclusions were obtained. 1. Using the Student's t-test for statistical analysis, it was suggested that the difference of the buccolingual location of occlusal contacts influenced the direction of the tooth displacement. 2. The tooth which had occlusal contact in the buccal cusp displaced in the mesio-buccal direction, so this may create a wide dental arch and a slight discrepancy was generated at the distal interproximal contact area of the tooth. 3. It was shown that the tooth which had occlusal contact in the buccal cusp rotated in the buccoapical direction in reverse to the natural tooth.     

Assessment of endodontically treated teeth adjacent to proposed implant sites

Many partially dentate dentitions are now being restored using dental implants; but assessment of endodontically treated teeth adjacent to the proposed implant sites has seldom been reported. Assessment criteria are given for sound- and endodontically compromised teeth to ensure adequate preimplant preventive and restorative treatment and to minimize the chances of failure of dental implants adjacent to these teeth. Cases are used to illustrate pitfalls in the treatment planning process.     

Analysis of working-side occlusal contacts

Bilateral interocclusal registrations were made of two working-side mandibular positions of 45 healthy young adults with morphologically good occlusions. The occlusal contacts were analyzed according to frequency and location. A large number of subjects presented unclassified patterns of articulations. In the group with known occlusal schemes, more individuals had "canine guidance" on the left side, whereas the most frequent pattern on the right side was "partial group function."     

Influence of occlusal adjustment by grinding on gingivitis and mobility of traumatized teeth

Abstract The effect on marginal inflammation and tooth mobility of occlusal adjustment by grinding was investigated in 43 occlusally traumatized teeth in 29 subjects with gingivitis and marginal periodontitis. The material consisted of 4 groups with tooth mobility of varying degrees of severity and bone destruction. In all groups increased tooth mobility decreased subsequent to occlusal adjustment. The latter was without effect on sulcus fluid flow rate or gingivitis scores in either gingivitis or periodontitis patients.     

上颌前牙美学区连续多颗牙缺失即刻种植的临床研究

目的分析不同牙种植系统上颌美学区即刻种植对种植体周围骨组织吸收的影响,并探讨改良微创H形切口在上颌美学区多颗相邻牙即刻种植修复的应用技巧及美学影响因素。方法选取2011年1月—2015年1月在我院口腔科接受牙体种植修复的患者58例,所有患者均在牙槽嵴顶作微创H切口,种植体采用潜入式手术。根据患者种植的牙体系统,将患者分为3组:3I组、DIO组、Replace组。随访12个月,观察患者种植体周围骨吸收量、探诊深度及术后龈沟出血指数。根据Miller牙龈边缘组织退缩分类及Jemt牙龈乳头指数,分别观察种植体永久修复12月后牙龈边缘退缩及牙龈乳头状况;根据Albrektsson种植体成功标准,观察所植入的种植体状况。结果 3组患者的周围骨组织骨吸收量在植入术后6个月均呈稳定的趋势,不同的种植体增长的幅度不同,差异无统计学意义(P>0.05),DIO组患者第3个月的骨吸收量显著高于Replace组和3I组,其差异具有统计学意义(P<0.05)。术后不同时期,3组患者的龈沟出血指数与天然牙相比,6个月时,DIO组患者的龈沟出血指数虽然高于天然牙,差异无统计学意义(P>0.05);9、12个月时,3组患者的龈沟出血指数与天然牙差异无统计学意义(P>0.05);术后6个月,3组患者的探诊深度呈稳定的趋势,各个时期3组患者的探诊深度略高于天然牙,差异无统计学意义(P>0.05)。159颗种植体存留率100%,Miller分类,136颗种植体牙龈边缘无退缩;18颗种植体牙龈边缘I类退缩;5颗种植体牙龈边缘Ⅱ类退缩。种植修复体近远中Jemt牙龈乳头指数均为Ⅱ级以上。结论不同牙种植体系统对美学区多颗相邻牙即刻种植的种植体周围骨组织及软组织均具有较理想的稳定性及美学效果。改良微创H形切口为相邻多颗牙即刻种植的应用技巧提供了临床依据,值得临床推广。     

Influence of occlusal forces on stress distribution in preloaded dental implant screws

STATEMENT OF PROBLEM: Abutment and prosthetic loosening of single and multiple screw-retained, implant-supported fixed partial dentures is a concern. PURPOSE: The purpose of this study was to investigate stress distribution of preloaded dental implant screws in 3 implant-to-abutment joint systems under simulated occlusal forces. MATERIAL AND METHODS: Three abutment-to-implant joint systems were simulated by using the 3-dimensional finite element analysis method: (1) Branemark external hexagonal screw-retained abutment, (2) ITI 8-degree Morse tapered cemented abutment, and (3) ITI 8-degree Morse tapered plus internal octagonal screw-retained abutment. A thermal load and contact analysis method were used to simulate the preload resulting from the manufacturers' recommended torques in implant screw joint assemblies. The simulated preloaded implants were then loaded with 3 simulated static occlusal loads (10 N; horizontal, 35 N; vertical, 70 N; oblique) on the crown position onto the implant complex. RESULTS: Numeric and graphical results demonstrated that the stresses increased in both the abutment and prosthetic screws in the finite element models after simulated horizontal loading. However, when vertical and oblique static loads were applied, stresses decreased in the external hexagonal and internal octagonal plus 8-degree Morse tapered abutment and prosthetic screws with the exception of the prosthetic screw of ITI abutment after 70-N oblique loading. Stresses increased in the ITI 8-degree Morse tapered cemented abutment after both vertical and oblique loads. CONCLUSION: Although an increase or decrease was demonstrated for the maximum calculated stress values in preloaded screws after occlusal loads, these maximum stress values were well below the yield stress of both abutment and prosthetic screws of 2 implant systems tested. The results imply that the 3 implant-to-abutment joint systems tested may not fail under the simulated occlusal forces.     

Influence of the deflasking delay time on the displacements of maxillary denture teeth

The purpose of this study was to investigate the displacement of teeth occurring in dentures following storage in water at a temperature of 37oC. Ten maxillary dentures were constructed with Classico heat-cured acrylic resin using conventional metal flasks. Metallic reference pins were placed on the incisal border of the central incisors (I), buccal cusp of the first premolars (PM), and mesiobuccal cusp of the second molars (M). The acrylic resin was polymerized twelve hours after final flask closure in a water cycle at 74oC for 9 hours. The flasks were removed from the thermo-curing unit after water cooling and then bench stored for 3 hours. After deflasking and finishing, the dentures were stored in water at a temperature of 37oC for periods of 7, 30, and 90 days. Following deflasking and each storage period tested, the I-I (incisor to incisor), PM-PM (premolar to premolar), and M-M (molar to molar) transverse distances, and LI-LM (left incisor to left molar) and RI-RM (right incisor to right molar) anteroposterior distances were measured with a STM Olympus microscope, with accuracy of 0.0005 mm. Colleted data were submitted to ANOVA and Tukey test (5%). No statistically significant difference was observed in the displacement of teeth in the transverse and anteroposterior distances.     

不同咬合接触对单颗后牙种植修复咬合平衡的影响

目的: 研究不同咬合接触方式对咬合平衡指数的影响,为改进种植修复咬合平衡提供依据。方法: 选择2018年12月—2019年12月上海市普陀区眼病牙病防治所行单颗后牙种植修复的患者24例,均采用标准化种植流程,按照修复体与对颌牙将被调整到的咬合接触紧密程度不同,随机分为A、B 2组,分别使用12 μm和20 μm咬合纸进行调整,使咬合纸在修复体和对颌牙咬紧时恰好可以有阻力抽出。应用T-scan咬合力分析仪分别测定修复前及修复当天、3个月、6个月、12个月和18个月牙尖交错位时咬合力分布情况,换算成咬合平衡指数。采用SPSS 21.0软件包对数据进行统计学分析。结果: 2组在修复前咬合平衡指数分别为（-0.389+0.066）和（-0.368+0.055）,修复当天分别为（-0.249+0.069）和（-0.283+0.056）,差异无统计学意义（P>0.05）;修复3个月时分别为（-0.052+0.022）和（-0.169+0.063）,6个月时分别为（-0.025+0.015）和（-0.088+0.045）,12个月时分别为（-0.010+0.008）和（-0.029+0.016）,18个月时分别为（-0.000+0.000）和（-0.006+0.008）,2组咬合平衡指数均呈逐渐增加至0的趋势,A组绝对值远小于B组,但A组的上升幅度远大于B组,差异有统计学意义（P<0.05）。结论: 单颗后牙种植修复能逐渐恢复咬合平衡,选用12 μm咬合纸调整修复体与对颌牙咬合接触紧密程度,能更早获得咬合平衡。