Precision attachment removable partial dentures.

Although added preparations and skill are required to provide precision attachment removable partial dentures, more favorable esthetics and load distribution may outweigh the disadvantages. Basic design principles, categories (intracoronal, extracoronal, stud, bar and plunger) and selection of precision attachments are reviewed.     

The size of occlusal rest seats prepared for removable partial dentures

OBJECTIVE: The aim of this study was to test whether rest seats cut by a group of general dental practitioners for a removable partial denture differed in size and shape from those prepared by either a group of postgraduate students or their academic teachers. METHOD: The occlusal surfaces of a number of plastic teeth were scanned by a laser profilometer. Each tooth was then placed in a set of articulated phantom head dental arches. 30 dental practitioners, 16 postgraduates and 11 dental academics were asked to cut a rest seat preparation in the mesial marginal ridge suitable for the construction of a removable chromium cobalt partial denture. The tooth was removed from the models, rescanned, and this data converted to grey level images for measurement of the width, length and area of each rest seat. Depth was calculated as the difference between the pre and post preparation scanned profiles. RESULTS: There was a wide variation in the size of the individual rest seat preparations. There was no significant difference between the measured parameters from the images of the preparations made by academic staff and postgraduate students. The two sets of data were therefore combined. The length, width and area of the rest seats prepared by the staff and postgraduate group were significantly greater than those cut by the dental practitioner group. However, there was no significant difference in the depths measured. The outline form of the rests prepared by the dental practitioners was often round with sharply defined margins contrasting with the smooth triangular preparation the staff and postgraduates prepared. CONCLUSION: A 'refresher' in tooth modification for GDPs designing partial dentures would improve the long term success of the prosthesis.     

Prefabricated metal intracoronal semiprecision attachments for removable partial dentures

The inaccuracies of the casting and fitting processes associated with semiprecision intracoronal attachment systems may compromise the fit of the completed prosthesis. The objective of using metal prefabricated intracoronal semiprecision attachments is to improve the adaptation between the matching attachment surfaces used in the fabrication of removable partial dentures. In milled dovetail or waxed dowel rests, the attachment of one side is completed and the other is cast to match. The prefabricated attachment system presented uses a matching component cast directly against the precast metal rest-mandrel. This reduces the inaccuracies resulting from waxing, investing, and casting.     

Repairs of metal parts of removable partial dentures

The clinical and laboratory phases of repairing broken clasps and major connectors have been described. These techniques offer clinically acceptable results and are a necessary part of removable partial denture service and maintenance.     

Rehabilitation of occlusal support by removable partial dentures with free-end saddles

This study aimed to assess the level of restored occlusal support by removable partial dentures with free-end saddles. The maximal clenching force of 61 subjects was measured using pressure sensitive film with and without their dentures. The restored level of occlusal support was estimated from the shift of the occlusal load centre. In comparison with previous results of experimental occlusions using splints for eight normal dentate subjects, the restored level using dentures ranged from 40-60% of that of natural teeth. The analysis of the shift of the occlusal load centre could reasonably evaluate the prostheses from the standpoint of occlusal support.     

Using removable partial dentures to stabilize teeth with secondary occlusal traumatism

The theoretical and practical considerations in treating secondary occlusal traumatism with removable prostheses have been discussed. Long-term success depends on a continued control of periodontal inflammation and occlusal traumatism. A recommended course of treatment was divided into three equally important segments of (1) periodontal therapy, (2) the removable prosthesis, and (3) close maintenance.     

A combination impression and occlusal registration technique for extension-base removable partial dentures.

The ultimate goal of a prosthodontic service is the placement and maintenance of prostheses which are in biologic and functional harmony with the supporting tissues and remaining teeth. The combination impression and occlusal registration technique minimizes clinical and technical procedures which might introduce errors. If accurately managed, this technique will provide optimum occlusion and mucosal support for extension-base removable partial dentures.     

Esthetic removable partial dentures

This article provides information regarding the many ways that removable partial dentures (RPDs) may be used to solve restorative problems in the esthetic zone without displaying metal components or conspicuous acrylic resin flanges. The esthetic zone is defined and described, as are methods for recording it. Six dental categories are presented that assist the dentist in choosing a variety of RPD design concepts that may be used to avoid metal display while still satisfying basic principles of RPDs. New materials that may be utilized for optimal esthetics are presented and techniques for contouring acrylic resin bases and tinting denture bases are described.     

Immediate removable partial dentures

This technique for immediate delivery of removable partial dentures bases its success upon correct diagnosis, careful treatment planning, and close cooperation among patient, laboratory technician, and dentist.     

Designing removable partial dentures

Various designs have been suggested for the more frequently- occurring situations of the partially edentulous state. Obviously, a discussion of all the probabilities of design is not possible. The important factor is that basic principles are not violated. Retainer choice, rest placement, major and minor connector design, and support of the distal extension base are all critical factors. However, the fact remains that adequate time must be spent in properly diagnosing the particular case and devising a workable treatment plan. A thorough oral and radiographic examination, accurate articulated diagnostic casts, and a profile of the patient in terms of prosthetic needs and expectations must all be made. Once this picture is in order, the rather mechanical task of laying out the "nuts and bolts" of removable partial denture design can be carried out to ensure that our patients receive the full benefits of our knowledge and skills.