A systematic approach for removable partial denture design

Implants are becoming increasingly popular as a means of restoring edentulous spaces. However, many patients still cannot afford implants or do not have enough bone to support them. For these patients, removable partial dentures are an option for restoring function to their dentition. This article presents a way of considering removable partial denture design without becoming overwhelmed and frustrated with the process. Retention, support, and stability are discussed.     

A systematic approach for removable partial denture design

Patients' attitudes, medical, surgical and financial considerations lead to the use of a removable partial denture (RPD) as the chosen prosthetic restoration even in the "dental implant era". The aim of this article is to describe a systematic approach to RPD design, so the RPD will be a long-term solution that will not harm the remaining oral tissues. There is an unlimited RPD design options. Choosing the right one involves considering biochemical factors, aesthetics and patients' comfort. A systematic approach starts with a correct diagnosis of the remaining hard and soft tissues, followed by a careful planning of support, stability and retention in that order. Additional elements should be added only at a later stage. A systematic track starting with a preliminary design, surveying of the model and analyzing the preliminary design on that surveyed model. If needed, that track should be reversed until an acceptable design is found. Support should ideally be achieved by using metal rests on healthy tooth structure. Tooth supported RPD are the most convenient ones and have a very good long-term prognosis. Old restorations or caries might impose changes from the ideal supporting rests. When posterior teeth are missing or when the edentulous area is vast, tooth-tissue supported RPD are used. In these cases one should gain initial support from the teeth and an additional support from the soft tissues. A denture base that is similar to a full denture base that would have been prepared for a fully edentulous patient should achieve this. If the prognosis of the potential supporting teeth is poor, a tissue-tooth supported RPD is considered. In these cases, the denture base is the primary supporting element, and stress relieving clasp-assemblies such as the RPI/RPA should be considered. Stability is achieved primarily by metal contacts between teeth and the metal framework of the RPD. In fact, any embracing part of the clasp assembly and a correct denture base can contribute to the stability. The distal parts of the retentive clasps produce the active retention. Since these parts generate lateral forces on the abutment teeth, a reciprocating element should be used. True reciprocation can only be achieved if the reciprocating element touches the tooth before the retentive clasp. After designing support, stability and retention, other parts should be considered. When a distal extension RPD is considered, an indirect retainer should be incorporated into the framework in order to prevent upward rotational movement of the denture. The major connector converts forces from one side to the other. In the upper jaw, that part acts also as a supporting element in Kennedy class I and class II cases. In other cases, a minimal type of a major connector should be chosen. As for minor connectors, these should only be added if other parts--such as guiding planes--couldn't be used for the purpose of connecting functional elements to the major connector. In any case, a 5 mm distance between two adjacent minor connectors should be allowed in order to prevent food from being trapped in that space. A systematic approach starts with diagnosis of the remaining tissues and with finding the correct prosthetic solution with the patient. If a RPD is the chosen solution, start designing with analysis of support, followed by stability and only then, decide upon the necessary retentive elements. All other parts should be considered later. Such a systematic approach will ensure a long-term solution and a happy patient.     

Cast-free fabrication of a digital removable partial denture with a polyetheretherketone framework

Digital workflows for removable partial dentures have enabled new machinable framework materials, including polyetheretherketone (PEEK). In addition, all denture components can be designed and manufactured digitally. Nonetheless, physical casts are still required for assembly of the components. The adoption of a cast-free fabrication procedure may enhance benefits, including a reduced number of procedures, faster processing, and reduced material waste. The purpose of this technical report was to demonstrate a workflow for the fabrication of a removable partial denture with a PEEK framework, milled teeth, and milled flanges, which uses intraoral scanning and no physical casts.     

The segmented framework removable partial denture

The segmented framework removable partial denture is made of two cast metal individual segments joined with a resin major connector. The small individual framework segments can be made to fit well and the design permits ready correction of the tissue surface of the major connector through relining or an altered cast procedure. The dentist is offered a valuable alternative treatment approach in selected patients.     

Novel fully digital workflow for removable partial denture fabrication

PurposeThis technical procedure report introduces a newly developed method for removable partial denture (RPD) fabrication using computer-aided design and computer-aided manufacturing (CAD/CAM) and rapid prototyping (RP) technologies.MethodsFull-arch digital impressions of the partially edentulous jaw were made by an IOS or the conventional method. The denture framework, artificial teeth, and denture base were designed by commercially available CAD software. Each of the denture components including connectors, clasps, and artificial teeth and the denture bases were fabricated separately by the CAM machine or the three-dimensional (3D) printer, and then assembled using an adhesive material.ConclusionsRPDs were successfully fabricated using fully digital workflow and delivered to the patient, and no clinical complications were reported. Within the limitations of this report, the newly developed RPD fabrication techniques have the potential to change clinical and laboratory workflow from analog to digital.     

Mandibular implant-supported removable partial denture with distal extension: a systematic review

Summary The aim of this article is to investigate patient satisfaction, survival rate of implants, and prosthetic complications or maintenance for rehabilitation with removable partial dentures associated with implants in mandibular Kennedy class I and II cases. A systematic literature review was conducted by three independent reviewers including articles published from January 1981 through September 2011. Medline and Cochrane Library electronic databases were used in addition to hand searching to assess clinical outcomes for mandibular implant-supported removable partial denture with distal extension. This review yielded 1751 records that were narrowed down to 5. The studies revealed implant survival rates ranging from 95% to 100% with one failure reported of 98 implants. The removable partial dentures associated with implant in mandibular free-end arches showed some complications and need of repair for relining, pitting of the healing abutment, replacement of resilient component of the attachment, damage in framework, screw loosening and damage in acrylic denture base. Patient satisfaction was evaluated through a five-point questionnaire, and results ranged between 4·12 and 5·0, considering 1 as the least favourable situation. The literature review showed increase in patient satisfaction and high survival rates of implants associated with mandibular removable partial dentures with distal extensions. However, some complications and need of prosthetic repair were reported. Although this treatment approach could represent a low-cost and beneficial rehabilitation for free-end mandibular ridges, the lack of controlled and randomised well-designed clinical trials suggests further studies with more representative samples to validate the outcomes of this treatment modality.     

CAD/CAM切削技术在可摘局部义齿支架制作中的应用

目的探讨计算机辅助设计与制作（CAD/CAM）切削技术在可摘局部义齿（RPD）支架制作中的临床应用效果。 方法选取2017年9月至2018年6月南京市口腔医院修复科就诊的Kennedy Ⅰ类牙列缺损患者共26例,采用随机数字表法分为传统方法组和CAD/CAM组,每组13例。常规制取精细印模,其中CAD/CAM组通过扫描石膏模型获取三维数据,CAD RPD支架形态,CAM切削生成支架树脂铸型,常规包埋铸造完成RPD金属支架。传统方法组以常规方法制作支架蜡型,包埋铸造完成RPD支架。临床试戴,比较两种金属支架就位情况,与口内软硬组织的密合度。采用秩和检验的独立样本Mann-Whitney检验进行统计分析。 结果传统方法组制作的RPD支架9例就位顺利,4例经少量调磨就位,而CAD/CAM组制作的RPD支架10例顺利就位,3例经少量调磨就位。两组RPD支架均无大量调磨仍无法就位的现象发生,就位情况间差异无统计学意义（U = 78.0,P = 0.5）。2组患者中均有12例支架密合,1例支架存在≤3处不密合部位的现象,密合情况之间差异无统计学意义（U = 84.5,P = 0.760）。 结论CAD/CAM切削支架蜡型制作的RPD金属支架修复效果可以达到临床要求。     

A technique for fabrication of an extracoronal attachment-retained removable partial denture to fit an existing fixed partial denture

Precision attachments have been used for many years to retain removable partial dentures (RPDs). Common reasons for a failed attachment-retained RPD are fracture of the framework, fracture of the roots or teeth, and irretrievable decrease of retention. When an RPD framework major connector has been fractured, it should be remade. This article describes a technique to remake a fractured mandibular RPD using cast round profile attachment analogs without the need for replacement of the fixed partial denture.     

A review of 243 errors possible during the fabrication of a removable partial denture: part III

In Part III of this series, possible errors 169 through 243, all of which may be committed during the fabrication of a removable partial denture, are presented. Suggestions for avoiding the problems and solutions for correcting them are described.     

A review of 243 errors possible during the fabrication of a removable partial denture: part II

In Part II of this series, possible errors 72 through 168, all of which may be committed during the fabrication of a removable partial denture, are presented. Suggestions for avoiding the problems and solutions for correcting them are described.     

A review of 243 errors possible during the fabrication of a removable partial denture: part I

Everyone who participates in any step of the fabrication of a removable partial denture must share in the success or failure of the restoration. Some seemingly innocuous deviations can be accumulative and cause serious problems, so everyone should review the procedures that they use on a regular basis. Parts I through III of this article present a personal and generic (but by no means comprehensive) list of errors that can occur when a removable partial denture is fabricated. Results that can be attributed to these errors are identified, and a possible solution for each error is described. This information is useful to the entire dental team: the dentist, dental assistant, office manager, and dental technician. The articles also include 18 notes that may be beneficial to personnel in the office and/or in the laboratory.     

Using removable partial denture framework as matrix for pin-retained restoration

A quick and easy method can restore a broken-down partial denture abutment with a pin-retained amalgam restoration. It has a high degree of patient acceptance as only one appointment is required, eliminating the need for the patient to leave a partial denture for adaptation to a wax pattern. The cost can be minimal. This technique can be used for Class II restorations; however, the practitioner must ensure sufficient clearance for the condenser to pass between the tooth and the partial denture, so all areas can be properly condensed.     

Fracture resistance of cingulum rest seats in CAD-CAM tooth-colored crowns for removable partial denture abutments

Statement of problem

The prevalent use of computer-aided design and computer-aided manufacturing (CAD-CAM) for tooth-colored ceramic materials has led to several case reports and retrospective clinical studies of surveyed crowns used to support removable partial dentures. How the specific contour of a cingulum rest seat affects the fracture resistance of these CAD-CAM tooth-colored materials is unknown.

整铸支架式可摘局部义齿美学设计的临床应用

整铸支架式可摘局部义齿以其适应范围广、稳定性好、固位力和支持力强以及坚固耐用、舒适卫生等优点,成为牙列缺损的一种最常用的义齿修复方式[1]。但美中不足的是对于需在前牙、双尖牙上设置唇、颊卡环者,可因金属显露影响美观而不能满足患者的审美心理需求。作者采用弹性树脂材料替代义齿有碍美观的金属卡环与热凝树脂基托的美学设计,既弥补了原义齿美学上的欠缺又不失其固有的优点,获得了良好的美学效果。材料与方法1、一般资料 本组病例73例,其中男性29例,女性44例。年龄25～53岁。修复体均需在前牙或（和）双尖牙的唇、颊面设置…     

可摘局部义齿支架几何模型的设计

目的:利用国产CAD/CAM软件系统,通过对可摘局部义齿支架的计算机辅助设计,探索开发适用于口腔修复专业义齿设计与数控加工制作的国产软件系统。方法:投影光栅测量法获取下颌KennedyⅡ类2亚类牙列缺损石膏模型的点云数据,在国产CAD/CAM系统中,进行数据精简,并在此点云数据基础上,确立观测线和就位道。按照临床设计原则,分别构建卡环、支托、舌杆、加强网等支架各部件的组织面与磨光面,包括舌杆的半梨形截面、加强网的内外终止线和组织终止点等特征性结构的构建,完成支架的三维几何模型计算机辅助设计。结果:成功建立了可摘局部义齿支架的几何模型。该模型可视性强,便于修改,支架与牙颌模型密合良好。模型的输出数据文件格式为STL,这种通用的传输格式有利于后续的计算机辅助制作。结论:基于国产CAD/CAM软件系统进行可摘局部义齿支架几何模型的设计是可行的。     

Complete denture fabrication using piezography and CAD-CAM: A clinical report

To provide maxillary and mandibular complete dentures for a patient with severe ridge resorption, the denture space was recorded using the piezography technique. After the piezographic space was scanned, a virtual tooth arrangement and festooning were performed within the space using computer-aided design software. The denture bases were milled from a polymethylmethacrylate resin block using computer-aided manufacturing, and commercially available denture teeth were bonded with resin adhesive. Using the piezography technique described, physiologically appropriate complete dentures were fabricated based on the neutral zone concept.