上颌牙列远中游离缺失可摘局部义齿60例临床分析

目的：比较上颌牙列远中游离缺失可摘局部义齿修复中U形大连接体与腭板宽腭杆大连接体的满意度。方法：回顾比较上颌U形大连接体与腭板宽腭杆大连接体可摘局部义齿修复患者各30例戴用1个月后满意度,用x2检验统计分析。结果：上颌U形大连接体与腭板宽腭杆大连接体义齿戴用后义齿满意度差别有统计学意义（P﹤0.05）。结论：戴用腭板宽腭杆大连接体义齿患者满意度较高。     

不同设计形式RPD对支持组织应力分布影响的光弹分析

目的:探讨分裂式设计与RPI设计制作的钴铬合金铸造支架RPD修复KennedyⅠ类缺损对支持组织应力分布的影响,为优化义齿设计提供实验依据。方法:分别以分裂式设计和RPI设计两种设计形式的钴铬合金铸造支架RPD修复下颌牙双侧游离缺失,用三维光弹应力冻结切片技术测试义齿加载后对基牙和缺牙区牙槽骨的应力分布,并加以分析比较。结果:钴铬合金分裂式设计的铸造支架RPD承受压力沿基牙牙体长轴传导,基牙远中所受扭力较小。结论:对于KennedyⅠ类牙列缺损,钴铬合金分裂式设计的铸造支架RPD使支持组织受力均匀、合理,减小了基牙受到的扭力,达到基牙保护的目的,是一种值得推广的设计。     

不同卡环设计对远中游离端牙列缺损基牙影响的临床研究

目的：不同卡环设计对远中游离端牙列缺损行活动义齿修复后对基牙影响的临床观察。方法：选择远中游离端牙列缺损患者74例,末端基牙均为前磨牙,分别采用RPI卡环,RPA卡环,RPT卡环进行活动义齿修复,修复3年后对基牙磨损、龋病、牙髓反应、基牙松动、基牙拔除、修复体失败等方面情况进行评估。结果：在基牙磨损方面,RPT卡环高于RPI卡环和RPA卡环,其余方面均无统计学差异。结论：RPT卡环易导致基牙磨损,三种卡环对基牙其它方面的影响没有显著差别。     

Influence of length and diameter of implants associated with distal extension removable partial dentures

PURPOSE: The aim of this study was to evaluate the influence of the length and diameter of the implant incorporated under the saddle of a distal-extension removable partial denture, acting as support. MATERIALS AND METHODS: Six hemi-mandibular models were made with the presence of left inferior cuspid and first bicuspid, with the following differences: model A, without removable partial denture; model B, removable partial denture only; model C, removable partial denture and implant of 3.75 x x mm; model D, removable partial denture and implant of 3.75 x x3 mm; model E, removable partial denture and implant of 5 x x mm; and model F, removable partial denture and implant of 5 x x3 mm. These models were designed with the aid of AutoCAD 2000 (Autodesk, Inc., San Rafael, CA) and processed for finite element analysis by ANSYS 5.4 (Swanson Analysis Systems, Houston, PA). The loads applied were 50 N vertical on each cuspid point. RESULTS: It was noted that the presence of the removable partial denture overloaded the supporting tooth and other structures. The introduction of the implant reduced tensions, mainly at the extremities of the edentulous edge. Both the length and diameter tended to reduce tensions as their dimensions increased. CONCLUSIONS: Increasing the length of the implant had a great influence on the decrease of displacement and von Mises tension values. Increasing the diameter of the implant had a great influence on the decrease of von Mises tension values, but did not influence the displacement values. According to the results of this study, it is a good choice to use the greater and larger implant possible in the association between implant and distal extension removable partial denture.     

Influence of length of food platform on masticatory performance in patients missing unilateral mandibular molars with distal extension removable partial dentures

Reduction of the size of food platform of a distal extension removable partial denture has been recommended to decrease functional load on the abutment teeth and residual ridges. The purpose of this study was to investigate the influence of shortening food platform on masticatory performance. Eight subjects unilaterally missing mandibular molars participated in the study. A unilateral design was used for the denture framework. The length of the food platform was changed as follows. Initially, (A) was adjusted so that the distal end of the platform was in accordance with the distal end of maxillary second molar. Next, the platform was shortened successively to 15 mm (B) and 10 mm (C). Subjects were asked to masticate 2-colored wax cubes to evaluate masticatory performance. Mixing Ability Index was calculated from the color mixture and the form of masticated cubes. Repeated measures one-way ANOVA indicated significant difference of Mixing Ability Index among platforms (P < 0.0001). The Dunnett's test indicated no significant difference between A (1.27 +/- 0.29) and B (1.36 +/- 0.29), and a significant difference between A and C (0.89 +/- 0.30), (P < 0.001). Masticatory performance decreased significantly when the length of food platform was shortened to 10 mm.     

Comparison of load transfer by maxillary distal extension removable partial dentures with a spring-loaded plunger attachment and I-bar retainer.

This study photoelastically compared the stress distribution characteristics of two maxillary bilateral distal-extension removable partial denture designs, one using I-bar retention and the other using a semiprecision spring-loaded plunger attachment. Each prosthesis was subjected to vertical and horizontal extension-base loads. Comparisons were made from photographic recordings of isochromatic fringe distributions. The two retention designs produced comparable stresses with splinting of abutments for the plunger attachment. The attachment-retained prosthesis proved less stable with some loadings. Stress patterns followed three trajectories in the maxilla. A basis for stress distribution comparisons to other maxillary removable partial denture attachments is established.     

Effect of implant support on mandibular distal extension removable partial dentures: Relationship between denture supporting area and stress distribution

PurposeThis study explored the relationship between implant support and the denture-supporting area by comparing the stability of an implant-supported distal extension removable partial denture and a conventional distal extension removable partial denture.MethodsA model simulating a mandibular bilateral distal extension missing (#34–37 and #44–47) was fabricated using silicone impression material as soft tissue (2 mm thick) on an epoxy resin bone model. The denture base was reduced by 5 mm cutting part of both the retromolar pad and the lingual border. Loads of up to 5 kg were applied, and the pressure and displacement of the RPDs were simultaneously measured and analyzed using the Wilcoxon test (α < 0.05).ResultsThe pressure on the bilateral first molar and the middle areas of the implant-supported distal extension removable partial denture (ISRPD) was significantly less than on the conventional RPD (CRPD). As the supporting area of the denture base decreased, the pressure and the denture displacement of the CRPD were greater than for the ISRPD.ConclusionThis study indicated that implant placement at the distal edentulous ridge can prevent denture displacement of the distal extension bases, regardless of the supporting area of the denture base.     

Influence of loading positions of mandibular unilateral distal extension removable partial dentures on movements of abutment tooth and denture base

PURPOSE: The aim of our study was to explore the effects of different loading positions on the movements of the abutment tooth and denture base of removable partial denture with unilaterally designed framework (RPD-U). MATERIALS AND METHODS: The experiment was carried out with a simulation model of a mandible without left molars. The movements of abutment tooth and denture base of the unilateral and bilateral designs were due to 30N vertical load on 12 loading positions determined with a strain gauge circuitry. The effects of loading positions on the movements of the abutment tooth and denture base were compared between two designs. RESULTS: During the loading on buccal, lingual positions, and the most disto-central position the movements of the abutment tooth and denture base of the unilateral design were significantly greater than those of the bilateral design (P < 0.01). During the loading on the three mesio-central positions the movements of the abutment tooth and denture base were equal between designs, and were significantly lower than during the loading on the other positions (P < 0.01). CONCLUSION: Ending the denture teeth at the mesial cusp of second molar and positioning the occlusal contacts over the ridge crest adequately stabilize the abutment tooth and denture base of RPD-U.     

Effect of implant support on distal extension removable partial dentures: in vitro assessment

The implants in implant-supported removable partial dentures (RPDs) are placed in the edentulous ridge to stabilize the RPD and minimize the resultant rotational movement. This study investigated the effect of implant placement on RPD stability. A model simulating a mandibular bilateral distal extension missing was fabricated using epoxy resin and silicone impression material as thin (1 mm) and thick (2 mm) soft tissues. Five pressure sensors (PS-10K, Kyowa, Tokyo, Japan) were attached near the left and right first molars (#36 and #46), first premolars (#34 and #44) and medio-lingual alveolar crest. Five bilateral distal extension RPDs with Co-Cr frameworks were conventionally fabricated. After the implants were placed at the bilateral second molar areas, healing caps (4.5 mm high) were connected to the denture base with autopolymerized resin to support the RPD. As in a conventional RPD, sealing screws were placed without connecting them. Loads up to 5 kg were applied, and the pressure and displacement of the RPDs (n = 5) were simultaneously measured and analysed using the Wilcoxen test (alpha = 0.05). There was less pressure on both thin and thick soft tissues, the #36, #46 and the medio-lingual alveolar crest from the implant-supported RPD than from the conventional RPD (P < 0.05). There were no significant differences in pressure on #34 and #44 between the two RPDs (P > 0.05). There was significantly less denture displacement of the implant-supported RPD than of the conventional denture (P < 0.05). Implant support helped prevent the displacement of distal extension RPDs and decreased the pressure on soft tissues.     

Patient satisfaction and preference with thermoplastic resin removable partial dentures: a randomised cross-over trial

PurposeThis randomised cross-over trial aimed to comparatively investigate patient preference and satisfaction with thermoplastic resin removable partial dentures (TR-RPDs) and conventional metal clasp-retained removable partial dentures (MC-RPDs).MethodsTwenty-eight partially dentate subjects were enrolled and randomised to receive MC-RPDs followed by TR-RPDs or vice versa (n = 14, each group). The subjects were asked to score overall satisfaction and denture-related parameters 3 months after delivery of each denture. Additionally, they were asked to choose their preferred denture type at the end of the trial.ResultsOf the 28 subjects, 24 (86%; mean age, 67.3 years) completed the trial. The overall satisfaction scores and ratings for oral appearance with TR-RPDs were significantly higher than those with MC-RPDs (P < 0.05). Moreover, 75% (18/24) and 83% (20/24) of the subjects reported greater overall satisfaction and better oral appearance with TR-RPDs than with MC-RPDs (P < 0.001, both). Scores for mucosal pain and food impaction were significantly better with TR-RPDs than with MC-RPDs (P < 0.05). Relative to MC-RPDs, TR-RPDs provided slightly better oral comfort and speech, although the differences were not statistically significant (P > 0.05). Scores for chewing ability, denture stability, and ease of denture cleaning were almost identical for both types of dentures.ConclusionsThese results suggest that TR-RPDs hold an advantage over MC-RPDs in terms of oral appearance and can offer greater satisfaction than MC-RPDs in partially dentate arches with at least an occluding pair in the posterior region.Clinical trial registrationUMIN Clinical Trials Registry (UMIN000007310).     

MK1附着体在老年患者单侧远中游离缺失修复中的临床应用

目的：评价MK1附着体修复老年患者单侧远中游离缺失的临床效果。方法：采用MK1附着体为23例单侧后牙游离缺失的老年患者进行修复治疗,经过8-44个月的随访,从主观感受、临床及X线检查评价修复效果。结果：所有患者对MK1附着体义齿的美观舒适性、固位力、咀嚼效能均感到满意;21例患者认为其摘戴方便。经配对t检验,MKl附着体义齿与原可摘义齿相比在美观舒适性、固位力、咀嚼效能方面均有明显优势（P〈0．05）;而在摘戴方面基本没有差别妒〉0．05）。2例患者出现了牙龈炎症,牙周治疗后炎症消失。3例患者进行了义齿可摘部分的重衬,其余患者基牙及缺牙区牙槽嵴无异常。结论：MK1附着体义齿稳定及固位性能良好,是一种较理想的修复老年患者单侧后牙游离缺失的修复体。     

Influence of working side contacts on masticatory function for mandibular distal extension removable partial dentures

The aim of this study was to clarify the influence of working side contacts for masticatory function for a distal extension removable partial denture. Five subjects who had edentulous arches from second premolar to second molar opposing natural teeth participated. Working side contacts were altered by using three types of artificial teeth attached to the denture base. A-form teeth made contact with opposite teeth while acting as the working side in a lateral excursion. The cusp angles of B- and C-form teeth were decreased by 10 degrees and 20 degrees, respectively compared with A-form teeth. B-and C-form teeth discluded with opposite teeth on the working side. Subjects were asked to perform two kinds of masticatory performance test. Obtained data were evaluated by the repeated-measures anova and the Tukey test for multiple comparisons. Results revealed that there was a significant difference (P=0.001) in the three types of teeth in the mixing ability test and the value of A-form teeth was statistically less value than those of the other teeth. However, there was no significant difference in the comminuting ability test. These results suggested that working side contacts between artificial teeth and opposite natural teeth influenced mixing ability, but not comminuting ability.     

单侧游离端义齿三种腭部连接形式的光弹应力分析

用光弹模型“冻结”法对三种不同位置腭杆的单侧游离端义齿进行侧向加载，研究缺牙区牙槽嵴、缺牙区同侧基牙和缺牙区对侧基牙的应力情况，分析连接杆传递和分散侧向力的作用。结果表明：腭连接杆的位置与侧向力的传递和分散有一定关系。前金属基托型单侧游离端义齿向缺牙区对侧基牙传递的侧向力比后腭杆型义齿传递的力小。单侧游离端义齿受侧向力时连接杆传递力的作用不明显，缺牙区牙槽嵴和同侧基牙承担主要载荷     

Clinical application of removable partial dentures using thermoplastic resin. Part II: Material properties and clinical features of non-metal clasp dentures

This position paper reviews physical and mechanical properties of thermoplastic resin used for non-metal clasp dentures, and describes feature of each thermoplastic resin in clinical application of non-metal clasp dentures and complications based on clinical experience of expert panels. Since products of thermoplastic resin have great variability in physical and mechanical properties, clinicians should utilize them with careful consideration of the specific properties of each product. In general, thermoplastic resin has lower color-stability and higher risk for fracture than polymethyl methacrylate. Additionally, the surface of thermoplastic resin becomes roughened more easily than polymethyl methacrylate. Studies related to material properties of thermoplastic resin, treatment efficacy and follow-up are insufficient to provide definitive conclusions at this time. Therefore, this position paper should be revised based on future studies and a clinical guideline should be provided.     

Influence of posterior dental arch length on brain activity during chewing in patients with mandibular distal extension removable partial dentures

It is well known that shortened dental arch decreases masticatory function. However, its potential to change brain activity during mastication is unknown. The present study investigates the effect of a shortened posterior dental arch with mandibular removable partial dentures (RPDs) on brain activity during gum chewing. Eleven subjects with missing mandibular molars (mean age, 66·1 years) on both sides received experimental RPDs with interchangeable artificial molars in a crossover trial design. Brain activity during gum chewing with RPDs containing (full dental arch) and lacking artificial molars (shortened dental arch) was measured using functional magnetic resonance imaging. Additionally, masticatory function was evaluated for each dental arch type. Food comminuting and mixing ability and the perceived chewing ability were significantly lower in subjects with a shortened dental arch than those with a full dental arch (P < 0·05). Brain activation during gum chewing with the full dental arch occurred in the middle frontal gyrus, primary sensorimotor cortex extending to the pre‐central gyrus, supplementary motor area, putamen, insula and cerebellum. However, middle frontal gyrus activation was not observed during gum chewing with the shortened dental arch. These results suggest that shortened dental arch affects human brain activity in the middle frontal gyrus during gum chewing, and the decreased middle frontal gyrus activation may be associated with decreased masticatory function.     

充填方式对种植义齿固定螺丝孔粘接强度及密封性的影响研究

 目的　研究不同充填方式封闭种植义齿固定螺丝孔对粘接强度及密封性的影响。方法　制作上颌第一前磨牙种植螺丝固位氧化锆冠试件80件，按照粘接前是否喷砂预处理、充填树脂种类、充填深度随机均分为8组，分别置于墨水溶液7 d，万能材料实验机上对螺丝孔内树脂充填体进行推出测试，记录树脂充填体脱粘接时的瞬间载荷，并取出树脂充填体，显微镜下观察记录并比较充填体染色的范围。结果    是否喷砂及树脂种类对粘接强度的影响均具有统计学意义（P < 0.01）；充填体厚度会显著影响粘接断裂载荷大小（P < 0.01），但对粘接强度的影响无统计学意义（P = 0.09）。喷砂后使用3 mm流动树脂充填微渗漏最少，不喷砂使用2 mm膏状树脂微渗漏最严重，是否喷砂、树脂种类及充填体厚度均对微渗漏有显著影响（P < 0.05）。结论    固定螺丝孔表面喷砂处理可增加粘接强度，减少微渗漏。流动树脂封闭种植义齿固定螺丝孔可获得相似的密封性及高于普通膏状树脂的粘接强度。在一定范围内，增加充填体厚度有助于提高固定螺丝孔封闭树脂的咬合承受力并减少微渗漏。     

含氟热凝树脂预防可摘局部义齿基牙龋的体外研究

目的:研究基托局部含氟对基牙的防龋作用.方法:将10颗健康离体牙制成20块2～3mm厚的釉质块,采用配对设计的实验方法,利用简易人工口腔装置,分别随机地紧邻于含氟及无氟热凝树脂块,流动人工唾液冲洗.每周测定人工唾液的氟浓度,四周后测定各釉质块的表面显微硬度及抗酸性.结果:两组中人工唾液氟浓度无显著性差异,表面显微硬度及酸蚀后的龋损深度有显著性差异.结论:含氟树脂有利于预防可摘局部义齿基牙龋.