Force-moment systems on single maxillary anterior implants: effects of incisal guidance, fixture orientation, and loss of bone support.

An engineering model of maxillary single anterior implants was developed to calculate the force-moment systems resulting from occlusal contacts. Analysis of a clinical example showed that flattening the incisal guidance and/or placing the implant in a more upright position reduced the moment and the labial component of the force but increased the intrusive component. The calculations are applicable to the design of implants and may help in the long-term evaluation of clinical success.

Endosseous implant placement in conjunction with inferior alveolar nerve transposition: an evaluation of neurosensory disturbance.

This retrospective study evaluated neurosensory dysfunction and the implant success rate associated with 64 implants placed in 15 patients following transposition of the inferior alveolar nerve. A total of 21 inferior alveolar nerve mobilization surgeries were performed. The mean postoperative follow-up time was 41.3 months, with a range of 10 to 67 months. The effects of surgical technique and implant surface geometry on neurosensory dysfunction were evaluated by using light touch, brush stroke direction, and two-point discrimination. The implant success rate was 93.8% (60/64). The surgical technique that involved detaching the mental foramen resulted in a significantly greater incidence of neurosensory disturbance (77.8%, 7/9) than did the technique that left the bony foramen intact (33.3%, 4/12). The overall incidence of neurosensory disturbance was 52.4% (11/21).

Mandibular fracture after endosseous implant placement in conjunction with inferior alveolar nerve transposition: a patient treatment report.

A patient with a severely atrophic right posterior mandible had three endosseous implants placed in conjunction with transposition of the inferior alveolar nerve. Three weeks following implant placement surgery, the patient experienced a spontaneous fracture of the mandible involving the two anterior implants. The two implants were removed, and the fracture was treated with open reduction and fixation with titanium mesh. The fracture healed, and the posterior implant integrated. This report suggests that the buccolingual and superior-inferior position of the mandibular canal can increase the possibility of mandibular fracture by increasing the size of the buccal cortical plate that is removed to expose the nerve during surgery.

Principles governing the prosthodontic treatment of patients with cardiac transplants.

As the survival rate of patients with cardiac transplants improves, it is more likely that dentists will have to provide extensive dental care and it is important to know the special precautions that must be taken when treating these patients. In this report on the prosthodontic treatment of a patient with a cardiac transplant and an unstable medical history, specific dental management guidelines are proposed. The treatment illustrates an alternative to complex and prolonged restorative treatment for patients with compromised post-transplant recovery.

Flapless anterior implant surgery: a surgical and prosthodontic rationale.

Full-thickness periosteal flap surgery is often accompanied by potential marginal bone loss and/or soft tissue recession. This is critical, particularly for the single-unit implant-supported restoration in the anterior maxilla, where the harmony of the soft and hard tissue architecture is of paramount importance to the development of natural aesthetics and function. This article demonstrates a flapless implant surgery technique in the anterior maxilla for optimal aesthetic results. The indications and limitations of this procedure are also discussed.

Predoctoral fixed prosthodontics education.

All current prosthodontic services will be needed well into the 21st century because millions of people are still without complete dentitions. However, knowledge of current and projected dental health needs indicates that the extent of usage of certain prosthodontic procedures will change because the number of edentulous patients will decrease. Presently there is considerable need and demand for extensive prosthodontic services and the need has been projected to grow. The demand for fixed prosthodontic services will likely increase in the future, particularly with the increased usage of new materials and treatment modalities. Recent data obtained from the American Dental Association Commission on Dental Accreditation indicate that failure rates on Part II of the National Board Dental Examinations and the prosthodontics section of Part II have remained relatively constant from 1980 to 1987. Total Part II failure rates for this time period have only ranged from 8.31 to 9.91 and on the prosthodontics section from 2.10 to 2.74. While these data do not predictably reflect clinical and technical skills or a knowledge of the most current didactic information, they do indicate that adequate knowledge had been provided to predoctoral students regarding the fundamental principles of prosthodontics. However, reductions have been made in prosthodontic curricular time. With the current escalation of knowledge in prosthodontics and allied areas and the increasing time constraints, it is becoming increasingly difficult to teach a thorough understanding of the basics and exposure to new developments. Any further reductions in curricular time will significantly compromise educational quality.

Gingival esthetics.

Achieving the most desirable gingival appearance enhances the esthetic result achieved with fixed prosthodontic restorations and is most often realized when gingival health is optimized before treatment and gingival trauma is minimized during treatment. Methods of optimizing gingival appearance by avoiding soft tissue contact are discussed as are factors considered important to maintaining good gingival appearance when subgingival margins are necessary.

Palladium-silver alloys: a review of the literature.

Since their introduction in 1973, the use of palladium-silver alloys has increased significantly and they now comprise a substantial part of the noble metal ceramic alloy sales in North America. Literature regarding various properties of this alloy system is presented with particular emphasis on castability, fit, and porcelain discoloration.

The prosthodontic management of endodontically treated teeth: a literature review. Part I. Success and failure data, treatment concepts.

Part I of this three-part literature review discusses the incidence of endodontic treatment required after prosthodontic procedures, whether crowns are needed on endodontically treated teeth, the primary purpose of posts, the causes of post and core failure, root fracture incidence data, and post design considerations. Pertinent questions are addressed based on the past 25 years of dental literature.

Eliminating coronal discoloration when cementing all-ceramic restorations over metal posts and cores.

Opaque procelain was fused over metal posts and cores. This procedure permitted the definitive all-ceramic restorations to possess a more uniform shade between teeth restored with metal posts and cores and adjacent vital teeth.

The prosthodontic management of endodontically treated teeth: a literature review. Part II. Maintaining the apical seal.

Part II of the three-part literature review series addresses factors related to prosthodontic treatment that can affect the apical seal and endodontic success.

The prosthodontic management of endodontically treated teeth: a literature review. Part III. Tooth preparation considerations.

The final part of this literature review series presents guidelines for the optimal preparation of teeth to receive posts and cores.

Tooth preparations for complete crowns: an art form based on scientific principles.

STATEMENT OF THE PROBLEM: No recent literature has reviewed the current scientific knowledge on complete coverage tooth preparations. PURPOSE: This article traces the historic evolution of complete coverage tooth preparations and identifies guidelines for scientific tooth preparations. MATERIAL AND METHODS: Literature covering 250 years of clinical practice was reviewed with emphasis on scientific data acquired during the last 50 years. Both a MEDLINE search and an extensive manual search were used to locate relevant articles written in English in the last 50 years. RESULTS: Teeth should be prepared so that they exhibit the following characteristics: 10 to 20 degrees of total occlusal convergence, a minimal occlusocervical dimension of 4 mm for molars and 3 mm for other teeth, and an occlusocervical-to-faciolingual dimension ratio of 0.4 or greater. Facioproximal and linguoproximal line angles should be preserved whenever possible. When the above features are missing, the teeth should be modified with auxiliary resistance features such as axial grooves or boxes, preferably on proximal surfaces. Finish line selection should be based on the type of crown/retainer, esthetic requirements, ease of formation, and personal experience. Expectations of enhanced marginal fit with certain finish lines could not be validated by recent research. Esthetic requirements and tooth conditions determine finish line locations relative to the gingiva, with a supragingival location being more acceptable. Line angles should be rounded, and a reasonable degree of surface smoothness is desired. CONCLUSIONS: Nine scientific principles have been developed that ensure mechanical, biologic, and esthetic success for tooth preparation of complete coverage restorations.

Clinical complications of osseointegrated implants.

STATEMENT OF PROBLEM: There is no comprehensive review of the literature that identifies the complications reported in clinical dental implant studies. PURPOSE: This article attempted to determine the types of complications that have been reported and to provide data regarding their frequency. METHODS: All available clinical studies from 1981 to 1997, published in English or with English abstract, that presented success/failure data regarding implant treatment were evaluated to determine the types of reported complications and to quantify implant loss as it relates to type of prosthesis, arch, time, implant length, and bone quality. RESULTS: Greater implant loss occurred with overdentures than with other types of prostheses. There was greater loss in the maxilla than mandible with fixed complete dentures and overdentures, whereas little arch difference was noted with fixed partial dentures. Implant loss increased with short implants and poor bone quality. The time of implant loss (preprosthetic vs postprosthetic) varied with type of prosthesis. Surgical complications included neurosensory disturbance, hematoma, mandibular fracture, hemorrhage, and tooth devitalization. Initial and long-term marginal bone changes were identified. Peri-implant soft tissue complications included dehiscence, fistulas, and gingival inflammation/proliferation. Mechanical complications were screw loosening/fracture, implant fractures, framework, resin base and veneering material fractures, opposing prosthesis fractures, and overdenture mechanical retention problems. Some studies also presented phonetic and esthetic complications. CONCLUSIONS: Although the literature presents considerable information on implant complications, variations in study design and reporting procedures limited the available data and therefore precluded proper analysis of certain complications.

Microleakage and shear bond strength of resin and porcelain veneers bonded to cast alloys.

Four resin veneering materials and four methods of retaining the veneer on metal castings were compared with metal ceramic restoration. Variations in microleakage were noted between the four resin materials retained by mechanical retention beads. When mechanical and chemical modes of a resin and porcelain veneer retention were compared, there was no microleakage with one mechanically and two chemically retained resin groups including one metal ceramic group. The resin materials tested understandably produced substantially lower shear bond strengths than the metal ceramic specimens. Higher shear bond strengths were recorded for the retentive beads than for the resins retained by three chemical bonding techniques. There was no direct correlation between microleakage and shear bond strength.

Recent graduates' and current dental students' evaluation of their prosthodontic curriculum.

This survey of recent graduates and third- and fourth-year dental students at Indiana University School of Dentistry determined whether the prosthodontic curriculum adequately prepared students for the prosthodontic portion of dental practice and whether there was material that should be added to or omitted from the prosthodontic curriculum. The survey evaluated 106 topics in the prosthodontic curriculum and areas related to prosthodontics. On the basis of their importance to the respondents, 59.4% of the topics were considered adequately emphasized, 2.9% of the topics were overemphasized and should be reduced in emphasis or eliminated, and 37.7% of the topics were underemphasized, which indicated the need to increase time devoted to these topics. Most of the underemphasized topics dealt with new materials, alternate techniques, private practice and its management, and the prosthodontic needs of special types of patients.

Moire topography for measuring the dimensional accuracy of resin complete denture bases.

Two methods of evaluating the accuracy of resin complete denture bases were compared by measuring the fit of four resin materials and two processing techniques. The use of moire topography was found to be comparable to measuring the weight of impression material retained between the denture base and master cast.

The application of Moire topography to removable prosthodontics.

The study was designed to assess the dental research potential of moire topography--the use of geometrically regular light patterns for measuring three-dimensional objects. One hundred thirty-nine maxillary edentulous casts and 20 mounted cast pairs were evaluated. Results demonstrated that the moire topography techniques can be used to quantitatively evaluate edentulous arch forms, compare edentulous ridge forms and surfaces, determine the amount of overlap of mounted maxillary and mandibular casts, and confirm prime areas for positioning posterior teeth.

The effect of tooth preparation design on the breaking strength of Dicor crowns: 3.

The dimensions of 120 maxillary first premolar all-ceramic tooth preparation designs were measured and analyzed to determine relationships between design features and recorded differences in the strengths of restorations fabricated for each preparation design. To assess clinical feasibility, the remaining dentin thickness of each preparation design was measured. A total occlusal convergence angle of 10 degrees provided the best combination of restoration strength and remaining dentin thickness. Five degrees produced the weakest restorations, and 15 degrees and 20 degrees required greater tooth reduction and pulp proximity. Stronger restorations were noted when the shoulder finish line had a sharp axiogingival line angle, possessed minimal cervical inclination, and was located as close as possible to the same occlusocervical level on all four axial surfaces.