Maxillary Rehabilitation Using Fixed and Removable Partial Dentures with Attachments: A Clinical Report

Despite requiring dental crown preparation and possible root canal treatment, besides the difficulty of clinical and laboratory repairs, and financial burden, the association between fixed (FPD) and removable partial dentures (RPD) by means of attachments is an important alternative for oral rehabilitation, particularly when the use of dental implants and FPDs is limited or not indicated. Among the advantages of attachment‐retained RPDs are the improvements in esthetics and biomechanics, as well as correction of the buccal arrangement of anterior teeth in Kennedy Class III partially edentulous arches. This article describes the treatment sequence and technique for the use of attachments in therapy combining FPD/RPD.     

无基托可摘局部义齿的临床应用

作者选择了４１例牙列缺损患者，为其设计并制作成无基托的可摘局部义齿，对其中的２９例作了追踪观察，效果良好。本文就无基托的ＲＰＤＳ的适应证，设计原则及患者的修复效果等方面进行了讨论。     

New Clasp Assembly for Distal Extension Removable Partial Dentures: The Reverse RPA Clasp

Several clasp types are used in distal extension removable partial dentures. In some cases the terminal abutments have only distal retentive undercuts that can be occupied by bar clasps; however, bar clasps may be contraindicated with no suitable alternative. This article presents a reasonable solution by introducing a new clasp design as a modification to the well‐known RPA clasp. The design includes a mesial rest, proximal plate, and buccal retentive arm arising from the rest and extending to reach the distal retentive undercut.     

可摘局部义齿基托对承托区腭粘膜微生物的影响

目的:了解基托戴入前后承托区腭粘膜微生物的变化及不同材料基托引起上述变化的差异。方法:检测备牙前、戴牙1月和3月时金属基托和塑料基托对应承托区腭粘膜面可培养菌总量及检出微生物组成比的变化。结果:戴牙1月和3月时,塑料基托对应腭粘膜可培养菌总量及乳杆菌、白色念珠菌组成比与备牙前相比均明显增加 (P<0105)。戴牙1月时,金属基托对应腭粘膜可培养菌总量及乳杆菌、白色念珠菌组成比与备牙前无明显变化。戴牙3月时,乳杆菌、白色念珠菌组成比与备牙前相比显著增加(P<0105)。两种材料制作的基托对应腭粘膜面可培养菌总量变化值无显著差异,但塑料基托所致白色念珠菌组成比的增加明显高于金属基托(P<0105)。结论:可摘局部义齿的戴用在基托与承托区腭粘膜间形成新的滞留区,有利于乳杆菌及白色念珠菌的繁殖。与金属基托相比,塑料基托更易促进白色念珠菌的生长。     

Systematic Clinical Evaluation and Correction Procedures for Support of Removable Partial Dentures

Support, retention, and bracing are the three main functions of a direct retainer in removable partial dentures (RPDs). RPDs must have sufficient supporting ability for proper occlusal rehabilitation. Support ability depends on the fit, size, shape, and location of the occlusal rest. Support cannot be adjusted chairside in most cases. The purpose of this article is to present systematic evaluation criteria for support in an RPD and to describe methods for adjusting cast clasps with improper support. Appropriate design of RPDs and preparation of abutments are also described.     

An Evaluation of Microwave-Polymerized Resin Bases for Removable Partial Dentures

Purpose The hardness, porosity, and adaptation of removable partial dentures fabricated with one heat-polymerized denture base resin and two resins designed for microwave polymerization were evaluated. Materials and Methods Five prostheses were evaluated for each resin. Adaptation of the denture bases to the master cast was evaluated by spatial orientation and mean weight of residual impression material. The prostheses were then embedded in epoxy resin and sectioned for evaluation of resin hardness (Knoop hardness) and microporosity. Results There were no significant differences in the adaptation of the acrylic resin bases for Acron MC and Ch Lucitone. There was no significant difference in the mean Knoop hardness values for any of the resin bases near and away from the metal. None of the denture bases showed porosity greater than 100 μm. Conclusions Both resin bases formulated for microwave polymerization were effectively polymerized around metal frameworks without adverse effects on resin hardness or porosity. Justi Denture Base material had poorer base adaptation than the other two resins.     

An Interactive Multimedia Solution to Learning Removable Partial Denture Design

Surveys of the dental profession and dental laboratories show that up to 60% of cases received by laboratories have little or no input from dentists into the design of their patients' removable partial dentures (RPD). Thus, there is a clear mandate for dental schools to teach RPD design in new ways that will give their students confidence and allow their graduates to approach the task readily and easily. This computer-aided learning program addresses that need. In designing it, we have exploited the unique properties of computers as a learning tool. The program uses Quicktime VR to simulate a three-dimensional perspective of diagnostic casts. It is also possible to incorporate animated diagrams to illustrate various points. Control of timed answers promotes the use of inquiry-based learning and allows the program to be interactive and completely problem-oriented. Students can practice at their own pace, on a variety of virtual cases, and thus learn the craft behind the art of designing RPDs. With this foundation, discussions with experts in the field regarding the patients they treat in senior years and as graduates can be conducted at a higher and more productive level. Student evaluation so far has been very encouraging.     

可摘局部义齿修复效果的调查

目的：研究可摘局部义齿的治疗结果并探讨与患者满意度有关的因素。方法：通过患者满意度的调查和临床检查，对63例戴可摘局部义齿5年以上的患者的治疗效果进行评价。结果：70％以上的患者对可摘局部义齿满意，约1／5的义齿需要修理，约1／3的修复体与基牙的龋患有关。结论：绝大多数患者戴可摘局部义齿5年后仍可使用修复体。     

Retention for a Removable Partial Denture

This article addresses the complex nature of retention in a removable partial denture. Retentive features range from magnets and springs to clips, clasps, and interfacial surface tension. The retentive quality of an extracoronal clasp varies with the alloy, physical form, location on the abutment, and positional relationship to other elements. Surveying to identify both occlusogingival and mesiodistal undercuts when the path of random dislodging forces are not definitely controlled is needed for effective retention. Augmentation of ineffective retention in existing clasps should concentrate on methods of deepening the undercut or increasing the suprabulge. Tightening of clasps already in contact with a tooth frequently produces adverse changes.     

Using a Visible Light‐Polymerized Resin to Fabricate an Interim Partial Removable Dental Prosthesis

An interim partial removable dental prosthesis (RDP) is any dental prosthesis that replaces some teeth in a partially dentate arch designed to enhance esthetics, stabilization, and/or function for a limited period of time, after which it is to be replaced by a definitive dental prosthesis. This article describes a technique that uses a visible light‐polymerized (VLP) resin as the base material for an interim partial RDP. This technique can be easily accomplished in a dental office or laboratory and results in a predictable dental prosthesis. This technique eliminates the need for laboratory processing.     

Periodontal and Prosthetic Conditions in Patients Treated with Removable Partial Dentures and Artificial Crowns: A Longitudinal Two-Year Study

In the present longitudinal study the periodontal and prosthetic conditions in 30 patients treated with removable partial dentures and artificial crowns were followed over a period of 2 years. The patients were given individual instructions in oral and denture hygiene and adequate periodontal treatment before the prosthetic therapy was started. The removable partial dentures were carefully planned and designed. The patients were regularly checked, and necessary instructions, scaling and prosthetic corrections were undertaken. The patients cooperated excellently and no significant deterioration was found in the clinical periodontal status of the remaining teeth. Only a few carious lesions were registered. The present study does not support the opinion that a removable partial denture per se will cause periodontal and carious lesions. When teeth with artificial crowns were examined regarding the position of the crown margins it was found that clinically observable gingival inflammations tended to be greatest when the crown margins were subgingivally located. Some deterioration of the removable partial denture occurred during the two-year follow-up concerning preferably occlusion, articulation, stability and clasp retention.     

Porcelain-Fused-to-Metal Pontics for Improved Removable Partial Denture Esthetics

A removable partial denture fabrication technique that uses custom-constructed porcelain fused-to-metal (PFM) pontics is described. PFM pontics enhance the dentist's shade matching effort in esthetically demanding situations.     

两种游离端半精密附着体可摘局部义齿的应力分析

目的:研究双侧游离缺失活动义齿使用两种不同类型的半精密附着体固位时周围支持骨的表面应力。方法:采用电阻应变测量法在人体下颌骨标本上测量以冠内栓道式及冠外垂直杆式半精密附着体固位的双侧游离缺失活动)固定联合修复体的表面应力值并做统计分析。结果:冠内附着体在基牙周围牙槽骨上产生的总体应力较大,而冠外附着体在缺牙区牙槽嵴和近缺隙侧基牙远中颈部牙槽嵴上产生的应力较大。结论:冠内附着体适用于远中基牙牙周条件良好的情况,而冠外附着体则适用于缺牙区牙槽嵴条件良好、远中基牙条件相对欠佳的情况。     

Photoelastic Study of the Support Structures of Distal-Extension Removable Partial Dentures

Purpose: The double system of support, in which the distal-extension removable partial denture adapts, causes inadequate stress around abutment teeth, increasing the possibility of unequal bone resorption. Several ways to reduce or more adequately distribute the stress between abutment teeth and residual ridges have been reported; however, there are no definitive answers to the problem. The purpose of this study was to analyze, by means of photoelasticity, the most favorable stress distribution using three retainers: T bar, rest, proximal plate, I bar (RPI), and circumferential with mesialized rest.
Materials and Methods: Three photoelastic models were made simulating a Kennedy Class II inferior arch. Fifteen dentures with long saddles, five of each design, were adjusted to the photoelastic patterns and submitted first to uniformly distributed load, and then to a load localized on the last artificial tooth. The saddles were then shortened and the tests repeated. The quantitative and qualitative analyses of stress intensity were done manually and by photography, respectively. For intragroup analyses the Wilcoxon test for paired samples was used, while for intergroup analyses Friedman and Wilcoxon tests were used to better identify the differences ( p < 0.05).
Results: The RPI retainer, followed by the T bar, demonstrated the best distribution of load between teeth and residual ridge. The circumferential retainer caused greater concentration of stress between dental apexes. Stress distribution was influenced by the type of retainer, the length of the saddle, and the manner of load application.
Conclusions: The long saddles and the uniformly distributed loads demonstrated better distribution of stress on support structures.     

The Effect of Removable Partial Dentures on Alveolar Bone Resorption: A Retrospective Study with Cone‐Beam Computed Tomography

Purpose: The aim of this study was to compare vertical and horizontal mandibular alveolar bone resorption by measuring bone morphological variation in Kennedy Class II removable partial denture (RPD) wearers and non‐wearers using cone‐beam computed tomography (CBCT). Materials and Methods: In total, 124 sites in the CBCT scans of 62 (29 RPD non‐wearers, 33 RPD wearers) Kennedy Class II patients were analyzed retrospectively. Three‐dimensional representations of the mandible with superimposed cross‐sectional slices were developed with the CBCT scans to evaluate the mandibular alveolar height and width by measuring distances between the mandibular canal, mylohyoid ridge, alveolar crest, and lower border of the mandible in four regions (eight sites) of Kennedy Class II non‐wearers and wearers of RPDs. Results: Mandibular alveolar bone height and width were significantly lower in edentulous sites when compared with dentate sites in both Kennedy Class II non‐wearers and wearers of RPDs (p < 0.05). Additionally, mean vertical and horizontal mandibular bone resorption was significantly higher in RPD wearers than in non‐wearers (p < 0.05). Conclusions: Vertical and horizontal alveolar bone resorption was found to be higher in the RPD wearing patients when comparing the dentate and edentulous sites.     

A Seminar/Case-Based Approach to Teaching Removable Partial Dentures to Predoctoral Students

This article describes a seminar/case-based, instructional model designed to simulate removable partial denture (RPD) problem-solving and decision-making processes encountered in third-year clinic in dental school and in dental general practice. Groups of approximately 20 second-year students (in the 3-year program) meet in a series of six 1-hour seminars during the first days of the course. Following the seminars, students complete an exercise on mouth preparation and multiple clasp and major connector designs on prototype casts. This is followed by survey-design exercises on casts of dentitions representing six variations of RPD requirements. Instructors assist students during the practice phase of each class. Each 2-hour practice session is followed by a 1-hour practical examination. The last day of the course is devoted to a comprehensive final practical examination on both maxillary and mandibular casts, incorporating any of the design features previously studied.