David R. Burns

Prospective clinical evaluation of mandibular implant overdentures: Part I—retention, stability, and tissue response

Seventeen subjects with preexisting conventional complete dentures were evaluated in this prospective clinical study. Two implants were placed bilaterally in the anterior mandible. In a crossover experimental design, the conventional dentures were modified, and the retention, stability, and tissue response for conventional dentures were compared with implant overdentures that had O-ring and magnet overdenture attachments for all subjects. The study indicated statistical superiority of the implant overdenture to the conventional denture. The O-ring attachment proved significantly better than the magnet attachment for retention and stability. The soft tissue response showed a slight but significant improvement with implant overdenture therapy.

A review of selected dental literature on contemporary provisional fixed prosthodontic treatment: Report of the Committee on Research in Fixed Prosthodontics of the Academy of Fixed Prosthodontics

One goal of the American Academy of Fixed Prosthodontics is regularly to publish comprehensive literature reviews on selected topics germane to the discipline of fixed prosthodontics. The following report is the result of this goal and focuses on provisional fixed prosthodontic treatment. Major subtopics include materials science and clinical considerations involving natural teeth and dental implants. The interrelationship between provisional and definitive fixed prosthodontic treatment is multifaceted and significant. Provisional therapy involves numerous materials and techniques that require special knowledge and technical experience. In this analysis, technical, clinical, and investigational articles are detailed and presented as a comprehensive literature review to provide contemporary guidelines. Referenced publications were found by conducting a Medline search and were limited to peer-reviewed, English-language articles published from 1970 to the present. Materials used with provisional treatment are discussed in terms of clinical selection and the influence of their physical properties on treatment outcome. Specific product names and manufacturers are included in this report only when they are cited in the original referenced publications.

Prospective clinical evaluation of mandibular implant overdentures: Part II—patient satisfaction and preference†

In a crossover experimental design, a prospective clinical study was performed with 17 subjects with existing complete dentures. After data collection, two implants were placed bilaterally in the anterior mandible. Conventional dentures were modified into implant overdentures by use of O-ring and magnet attachments. Each attachment was maintained with each subject for 6 months. Subjects responded to patient satisfaction and preference questionnaires about the conventional denture and each attachment. Subjects were satisfied with both attachment overdentures but showed a strong preference for the O-ring. Both attachments resulted in a significant increase in patient satisfaction when compared with the conventional denture.

Stress distribution surrounding endodontic posts

This study compared the stress distribution during insertion and function of three prefabricated endodontic posts with different designs using the criteria of post length and diameter. Test blocks of photoelastic material were prepared with simulated endodontic canals. Three posts for each design, diameter, and depth were cemented. Each specimen was examined and photographed without load, with 135 Newton (N) compressive force, and with 90 N and/or 135 N oblique force applied at 26 degrees by use of a circular polariscope. Para-Post and Para-Post Plus posts produced similar, evenly distributed patterns of stress using the criteria of diameter, depth, and load. Flexi-Post posts produced asymmetric stress patterns with concentration of stress at each thread. During compressive loading and after cementation alone, Flexi-Post posts displayed significantly higher shoulder stresses and substantially greater stresses along the coronal surface of the posts length than Para-Post and Para-Post Plus posts. Apical stresses were similar for Flexi-Post, Para-Post, and Para-Post Plus posts during compressive loading.

Template for positioning and angulation of intraosseous implants

Presurgical planning for submerged implant location and angulation within bone relative to the opposing occlusion is important for the prosthodontist. This information is accurately communicated to the surgeon by using a surgical template. A technique for fabrication of the template is described.

Randomized, prospective, clinical evaluation of prosthodontic modalities for mandibular implant overdenture treatment

STATEMENT OF PROBLEM Mandibular implant overdentures provide improved treatment outcome than conventional denture therapy, but there is controversy as to which overdenture treatment is the best choice. PURPOSE This study evaluated 3 different mandibular implant overdenture treatments with respect to prosthesis retention and stability, tissue response, patient satisfaction and preference, and complications to determine treatment outcomes. MATERIAL AND METHODS In a prospective, randomized clinical trial, using a crossover design, 30 subjects (mean age, 58.9; 63% male) received 4 implants in the anterior mandible. For each subject, 3 different overdenture attachment types were fabricated and/or fitted to the implants. These included a 4-implant bar attachment fitted to all 4 implants, a 2-implant bar attachment, and 2 independent ball attachments. Subjects were randomly assigned to 1 of 6 possible treatment sequences and received all 3 attachment types each for approximately 1 year. Data were collected at baseline, and at 6 and 12 months for treatment types. Denture retention and stability and parameters of soft tissue response were recorded. Complications were documented and questionnaires were used to identify subject masticatory ability, denture complaints, and preferences. Data were analyzed to determine statistical equivalence among the 3 different treatments using the Schuirmanns two one-sided test (TOST) procedure, and the Wilcoxon-Mann-Whitney TOST procedure (α=.05). RESULTS Force gauge prosthesis retention measurements showed that the 3 treatment types were not statistically equivalent, with the 4-implant bar demonstrating the greatest retention. Criterion-based retention scores were statistically equivalent for all treatments. Both the force gauge and criterion-based prosthesis stability measurements were statistically equivalent among all 3 treatment types. Analysis of all other multiple criterion-based scoring systems indicated the majority of these variables demonstrated equivalence. Where equivalence was not identified, the most favorable responses were typically found with the O-ring treatment, and the least favorable with the 4-implant bar treatment. From the small percentage of treatment visits demonstrating minor complications, no single treatment presented with greater complications than the others. For the treatment preference among subjects, 52% selected the independent ball attachment, 32% the 4-implant bar, and 16% the 2-implant bar (P=.10). CONCLUSIONS The 2-implant independent treatment used in this study provided equivalent or more favorable treatment outcomes for most measured parameters relative to the more complex and costly 2- and 4-implant bar attachments. The 4-implant bar treatment provided greater prosthesis retention than the other treatment types in this study, but after experience with all systems, subjects were more satisfied with and preferred the independent implant treatment.

Comparison of the retention of endodontic posts after preparation with EDTA

Significant differences in the retention of preformed endodontic posts for endodontically treated teeth were determined with (1) parallel-sided, passively placed Para-Post dowel versus mechanically engaging, threaded Flexi-Post dowel; (2) irrigation of canals with EDTA; (3) cementation with urethane dimethacrylate resinous or zinc phosphate cement. It was hypothesized that EDTA would substantially increase retention by removing the smear layer on the prepared canal wall and create micromechanical retention in the dentin. Extracted teeth were prepared with endodontic posts and divided in groups representing combinations of variables. The forces for post removal and the locations of the retentive bond failures were recorded. The results indicated that EDTA did not significantly affect retention. The Flexi-Post dowel was significantly more retentive than the Para-Post dowel but also exhibited a greater potential for tooth damage compared with the Para-Post dowel during retentive failure loads.

Removable partial denture design and fabrication survey of the prosthodontic specialist

In an effort to better understand and define the present standard of practice for removable partial denture design and fabrication, a questionnaire was prepared and distributed to prosthodontic specialists and graduate students or residents attending the American College of Prosthodontists annual meeting in 1987. The survey was designed to determine the philosophies and techniques used by prosthodontic specialists in treatment involving the removable partial denture. There were 195 questionnaires completed and used in determining the results. The results indicate areas of general agreement. Comparison with other data shows areas of controversy, but prosthodontists tend to follow techniques and philosophies similar to what is taught in most U.S. dental schools and what is recommended by the Academy of Denture Prosthetics.

Transfer impression for accurate adjustment of a metal coping insert for the submerged implant.

A technique allowing accurate alignment and interocclusal spacing of the coping insert for submerged implants has been described. Transferring the coping from the mouth to the master cast will provide predictable treatment results and is particularly useful when intraoral visualization is difficult.