Treatment of edentulism using Astra Tech implants and ball abutments to retain mandibular overdentures.

The goal of this study was to provide evidence to support simplified treatment of mandibular edentulism using denture fabrication and implant placement to circumvent the need for second-stage surgeries or prosthodontic superstructures. A 5-year prospective clinical trial is reported, which involved treatment of mandibular edentulism using the single-stage surgical placement of a TiOblast microthreaded titanium screw implant with immediate replacement of a relieved mandibular overdenture and eventual retention of the overdenture with reduced ball abutments. Fifty-eight patients were treated; 116 implants were placed using a single-stage surgical approach, with a duplicate mandibular denture as the tomographic/surgical template. Mandibular dentures were relieved and relined with a tissue conditioning material and placed immediately after implant surgery. After 3 months, Conical Seal Design ball abutments were placed and attachments were secured in the overdentures by heat-polymerizing laboratory reline methods. Five of the 116 consecutively placed implants failed at 2 to 4 months, providing an immediate implant survival rate of 95.69% at the time of attachment connection. Pain and inflammation were not common to all failures, and infection was not reported in any of the 5 failures. The immediate placement of implants by a single-stage surgical procedure in the parasymphyseal region of the mandible, followed by placement of a relined mandibular denture, results in predictable and asymptomatic healing of implants that display the clinical and radiographic features of osseointegration. Encouraging results at the immediate observation period (attachment connection) must be tempered by the need for prudent and detailed clinical and radiologic evaluation over the 5-year trial period.

Survival rates of teeth adjacent to treated and untreated posterior bounded edentulous spaces.

It is widely assumed that if posterior bounded edentulous spaces, or BESs, are not treated, the adjacent teeth ultimately will be lost. The authors examined this assumption by determining the survival of teeth adjoining 569 treated and untreated BESs. In the short term, the assumption was not supported. The great majority of untreated BESs did not result in loss of an adjacent tooth. Treatment with a removable partial denture did not increase the likelihood of adjacent tooth survival, while treatment with a fixed partial denture did result in modestly improved survival of adjacent teeth.

Prognostic variables associated with implant failure: a retrospective effectiveness study.

The purpose of this study was to determine implant survival rates by means of life table analyses for a cohort of patients not part of a prospective efficacy trial and treated by practitioners at varying experience levels. Prognostic variables associated with implant failure were identified by means of proportional hazards models and advanced statistical methods that account for patient effects. Ninety-nine consecutive patients treated from 1987 to 1991 with follow-up to 1994 were included in this retrospective study. A total of 384 dental implants (79.7% Brånemark, 19.3% IMZ plasma-sprayed, 1% IMZ hydroxyapatite-coated) were placed and subsequently supported 108 prostheses. Survival and proportional hazards modeling were used to generate Kaplan-Meier survival curves and to identify variables associated with implant failure. Survey data analysis was used to adjust for any patient effects for variables identified as significant through the proportional hazards models. Thirty-four implants failed over the follow-up period (median follow-up time 3.6 years), resulting in an overall failure rate of 8.9%. Seventeen of 99 patients experienced an implant failure. When prosthesis type was excluded from the modeling process, survey data analysis identified posterior location and an implant width of less than 4.0 mm as being associated with implant failure (all P < .05).

Meta-analysis of fixed partial denture survival: prostheses and abutments.

STATEMENT OF PROBLEM: Few estimates of the probability of various outcomes associated with replacement of missing teeth with fixed partial dentures have been reported. Existing longitudinal studies have reported widely disparate results for the survival of fixed partial dentures, but these studies have used different definitions of failure and varying periods of follow-up. PURPOSE: This study used meta-analysis to formulate annual probability estimates for three categories of fixed partial denture or abutment survival. METHODS: A systematic review of the English language literature since 1960 identified eight studies that met the preset inclusion criteria. Estimated annual survival proportions were back-calculated based on the Kaplan-Meier model and these proportions were combined through a fixed effects model meta-analysis. The probabilities and corresponding 95% confidence intervals at 5, 10, and 15 years for the three categories of survival are reported. RESULTS: For the aggregate population represented by the limited longitudinal studies available, this meta-analysis indicated that less than 15% of fixed partial dentures were removed or in need of replacement at 10 years; whereas, nearly one third were removed or in need of replacement at 15 years. Less than 5% of abutments were removed at 10 years.

Variation in the use of crowns and their alternatives.

The use of crowns and their alternatives for the restoration of compromised posterior teeth is of interest to educators, purchasers, and patients. Considerable curricular time is devoted to learning these techniques, substantial amounts of money are spent on these procedures, and differences in the outcomes of these treatments may have consequences for tooth survival. To begin to understand more about the actual use of these procedures, the provision rates of these services in a sample of U.S. dental practices were examined. This study reports on the extent to which utilization patterns and subsequent costs of crowns and their alternatives were associated with certain patient and practice characteristics. Insurance claims for dental services submitted by general dental practices through an electronic claims clearinghouse were used. Crown ratios (crowns/crowns plus alternatives) were calculated for dental practices to evaluate relationships with available explanatory variables. Findings indicated that older patients were significantly more likely to receive crowns than those in younger groups, resulting in as much as a 33 percent increase in the mean per tooth cost of treatment in the oldest group. Regional variation existed in the provision of crowns and resulted in up to a 31 percent difference in the mean per tooth treatment cost between regions. Crown ratios exhibited variation beyond that accounted for by patient and practice factors, thus raising questions about the consistency of treatment recommendations among dentists. These findings support the need to examine further the consistency of crown use among general dentists and to modify current approaches for teaching treatment planning in predoctoral restorative curricula.

Case-control study of non-carious cervical lesions.

An exploratory case-control study of non-carious cervical lesions was undertaken to examine the effects of a variety of risk factors. Candidate exposure variables were related to erosion, abrasion, and tooth flexure, the three principal putative causal mechanisms for cervical lesions. Because previous studies have tended to focus on specific causal mechanisms, evidence for a multifactorial etiology is inconclusive. Data describing exposure factors were obtained through clinical examination, dietary and behavioral questionnaires, and analysis of study casts from 264 subjects (137 cases, 127 control). Salivary data were also obtained for a subset of these subjects. Patient and tooth-level logistic regression models were constructed for the full subject group, and the subset with salivary data. For the two patient-level models, only exposures related to brushing entered. For tooth-level models, multiple exposures representing all three causal mechanisms were included in both models. The results suggest that non-carious cervical lesions do have a multifactorial etiology, and that multiple causal mechanisms may operate in the initiation and progression of individual lesions.

A conceptual framework for understanding outcomes of oral implant therapy.

The use of implants has expanded so rapidly that its effectiveness for many clinical situations has not been firmly established. Dentists are responsible for making appropriate therapeutic recommendations for the management of partial and complete edentulism. These decisions require an understanding of the consequences or outcome of treatment approaches. Outcome measures to evaluate the benefits of alternative therapies include longevity as well as physiologic, psychologic, and economic impacts. Future research should include outcome measures beyond implant prosthesis survival to more fully assess the practical impact of dental implants on the patient's oral health and to determine the most cost-effective approaches for managing completely and partially edentulous patients.

Predictable impression procedures for complete dentures.

This article outlines those techniques and materials that will optimize the clinician's ability to obtain predictable complete denture impressions using the selected pressure philosophy. Fabrication of a custom tray is crucial to the ultimate outcome of exemplary impressions. Alternative methods for border molding the custom tray are presented.

General dentists' patterns of restoring endodontically treated teeth.

The manner in which endodontically treated teeth are restored influences tooth longevity and the cost of treatment. This article describes a study of how surveyed general dentists restored endodontically treated teeth and whether their methods were consistent with those suggested in the literature. Some patterns of restoration did reflect the literature's recommendations, but overall the findings call into question some of the ways in which post-endodontic restorative care is carried out.

Management of the maxilla after alveolar ridge augmentation with hydroxylapatite when opposed by mandibular implants.

Maxillary ridge augmentation and vestibuloplasty are often adjuncts to mandibular implant reconstructions. Careful management of the augmented ridge after surgery is critical to the success of the maxillary prosthesis and osseointegration of the mandibular implant. A technique is described for alteration of an existing maxillary complete denture after ridge augmentation. Precautions regarding prosthesis function during the osseointegration phase of different types of mandibular reconstructions are noted. Technique and rationale for denture flange modification when a prosthesis is rebased for a patient who received simultaneous vestibuloplasty and ridge augmentation are described.

Surface roughness of two polished ceramic materials.

Conventional and CAD-CAM ceramic restorations often require adjustments that result in a need to reduce surface roughness. Surface roughness resulting from five polishing systems on two ceramics was assessed. Disks of Ceramco II and Dicor MGC ceramic blocks were polished with five combinations of 45, 25, and 10 microns diamonds; a 30-fluted carbide; three silicon carbide-impregnated rubber points; 4 and 1 micron diamond gels; and an aluminum oxide point and two aluminum oxide pastes. Five profilometer average roughness measurements (Ra) were taken of five replications of each step in each sequence. Controls were autoglazed Ceramco II and Dicor MGC ceramic specimens milled with a Cerec diamond wheel. Feldspathic porcelain could be polished smoother than glazed. Dicor ceramic could be polished smoother than Ceramco II ceramic. Finishing diamond points followed by diamond gels produced the smoothest surface. A 30-fluted carbide did not improve smoothness as used. The aluminum oxide point followed by aluminum oxide pastes was equivalent to finishing diamonds and gels for Dicor ceramic.

Effects of water, speed, and experimental instrumentation on finishing and polishing porcelain intra-orally.

Previous studies indicated that porcelain can be polished smoother than glazed porcelain with instruments suitable for intra-oral use. This study evaluated several experimental instruments and materials to determine if polishing could be done more efficiently. Scanning electron microscopy was used to evaluate the surface texture produced by different combinations of experimental instruments applied with high and moderate speed, wet and dry, to porcelain disks. No sequence matched the polished standard. However, the optimum surface texture was obtained with diamond instruments (with progressively smaller particle sizes) used at a moderate speed with water, followed by a 30-fluted carbide bur at high speed and dry, then diamond polishing paste on a webbed rubber cup. In all polishing sequences tested, the best results were obtained with each individual instrument when diamond instruments were used at moderate speed wet, and when carbide instruments were used at high speed dry.