David M. Bohnenkamp

Removable Partial Dentures: Clinical Concepts

This article provides a review of the traditional clinical concepts for the design and fabrication of removable partial dentures (RPDs). Although classic theories and rules for RPD designs have been presented and should be followed, excellent clinical care for partially edentulous patients may also be achieved with computer-aided design/computer-aided manufacturing technology and unique blended designs. These nontraditional RPD designs and fabrication methods provide for improved fit, function, and esthetics by using computer-aided design software, composite resin for contours and morphology of abutment teeth, metal support structures for long edentulous spans and collapsed occlusal vertical dimensions, and flexible, nylon thermoplastic material for metal-supported clasp assemblies.

Dimensional stability of occlusal splints

Five fabrication techniques and two storage methods were used to construct and store specimens to investigate the dimensional stability of acrylic resin occlusal splints. A research model was developed to more closely approximate the tooth coverage limits of occlusal splints. Ten specimens were fabricated on individual stone casts for each of the five techniques. Four die pins were transferred to each specimen, and the distances between the inside diameters of the pins were measured over a 2-week period. After construction, initial measurement, and removal from the cast, each acrylic resin specimen was stored in either a wet or a dry environment. Measurements between pins were made and recorded at five time intervals. The sprinkle-on techniques resulted in less dimensional change than the dough application, the vacuum-adapted resin sheet and dough application, and the heat-cured denture processing techniques. Acrylic resin specimens stored in a wet environment showed less distortion 2 weeks after fabrication.

Comparison of implant and provisional placement protocols in sinus-augmented bone: a preliminary report.

PURPOSE To evaluate preliminary data on clinical outcomes associated with timing of placement of single implant-supported provisional crowns and implants in augmented bone. MATERIALS AND METHODS Twenty patients underwent sinus elevation bone grafting followed by a 6-month healing period before implant placement and immediate placement of a provisional crown (group [G] 1); 20 patients received sinus elevation bone grafting at the time of implant placement and immediate placement of a provisional crown (G2); 20 patients required no bone augmentation before implant placement and immediate placement of a provisional crown (G3); and 20 patients received sinus elevation bone grafting followed by a 6-month healing period before implant placement followed by a 6-month healing period before restoration (G4). The height of the crestal bone was measured and recorded to determine mean bone changes, and success rates were determined. RESULTS Mean bone level comparisons were made between G2 and G3, G2 and G4, and G3 and G4. No statistically significant differences were found between the groups (P < .05). G1 was discontinued based on the initial results: two implants did not meet the 35-Ncm insertion test, and one implant failed within 1 month after implant placement. The 1-year implant survival rates were 86% (n = 12/14), 95% (n = 19/20), and 100% (n = 16/16) for G2, G3, and G4, respectively. Differences in survival rates between the groups were not statistically significant (P < .05). CONCLUSION Implant survival is affected by the timing of sinus augmentation and implant placement in relation to the timing of crown placement. Implants that were restored immediately regardless of the timing of bone augmentation showed greater failure rates than implants in augmented bone with delayed restoration protocols or those that were restored immediately in sites without bone augmentation. Neither the timing of loading nor timing of implant placement in relation to bone augmentation surgery affected mean bone loss.

Replacement of a fractured unilateral removable partial denture with a nonrigid fixed prosthesis: A clinical report☆

Replacement of a fractured unilateral RPD with a five-unit nonrigid FPD was described in this clinical report, with the following advantages. (1) Swallowing or aspiration of a unilateral removable prosthesis will be avoided. (2) Fracture of solid metal connectors is diminished. (3) Metal-ceramic retainers and pontics will improve the patients esthetic and functional demands.

A procedure for design of a posterior resin-bonded prosthesis

A procedure is described that uses red and brown crayon-type pencils and graphite pencil lead with a surveyor to draw a color-coded design on a study cast before fabrication of a posterior resin-bonded prosthesis. During diagnosis and treatment planning, abutments on the study cast are analyzed for undercuts and the height of contour on each abutment tooth is marked with a graphite pencil lead. Metal retainers for the prosthesis are indicated with brown lines drawn on the abutments. Enamel surfaces requiring alteration to allow insertion of the prosthesis and provide resistance to displacement are marked in red on the study cast. The surveyed color-coded study cast can be used as a reference guide by both the clinician and the laboratory technician during fabrication of the posterior resin-bonded prosthesis.

Runner bar modification for mandibular removable partial dentures

Breakage of a segment of an acrylic resin denture base of a mandibular removable prosthesis may result from inadequate retention and support. The runner bar modification can be a solution for this problem, especially where excessive crown length is to be restored in the mandibular anterior region. A technique is described for placement of a 14-gauge (1.7 mm) round wax runner bar that conforms to the anterior arch form on the removable partial denture wax-up. Wax vertical struts are added between the denture base retention and the runner bar. Improved retention and rigidity, without compromising esthetics and function, can be obtained through use of this procedure.