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 Schuirmann's 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.

The mandibular complete overdenture.

Mandibular complete overdenture treatment has been available for decades, but its use was limited when the treatment relied on retained teeth as overdenture abutments. This treatment, however, is currently experiencing more popularity than ever before. In fact, dentistry may be experiencing a philosophical shift, in which mandibular implant overdenture treatment may become the new standard of care for the treatment of the edentulous mandible. Practitioners are looking for simplified treatments that can provide cost-effective alternatives to more complex implant prosthodontic procedures. Implant overdentures provide a strong return for the investment in treatment time and expense and are a treatment suited to the lower socioeconomic status of many edentulous patients. The clinical outcome of this treatment is significantly better than that achieved with conventional mandibular dentures, especially when patients are experiencing technical problems because of compromised prosthesis retention or stability.

Influence of a 3-step tooth disinfection procedure on dentin bond strength.

STATEMENT OF PROBLEM: Clinicians have used disinfection materials to remove surface contaminants during cavity preparation. It has been postulated that disinfection materials may negatively affect shear bond strength of restorative materials. If so, large numbers of restorations may be predestined for early failure with the use of a disinfection protocol. PURPOSE: The purpose of this study was to determine whether there is a difference in the bond strength between dentin and resin composite with a 3-step disinfection technique compared to a conventional bonding technique without the additional disinfection protocol. MATERIAL AND METHODS: Sixty human molar teeth were sectioned parallel to the occlusal surface to expose mid-coronal dentin and mounted parallel to a bond shearing device on a universal testing machine and divided into 2 groups. In the 3-step disinfection group (n = 30), specimens were treated with chlorhexidine, Tubulicid red, and sodium hypochlorite before dentin bonding, following the manufacturer's instructions for All Bond 2. In the control group (n = 30), specimens were treated only with the bonding protocol of All Bond 2. To ensure a uniform bond surface area, core paste was syringed into a cylindrical mold (2.38-mm diameter and 2.00-mm height) that was in contact with the dentin bonding surface of each specimen and allowed to polymerize under constant force. All specimens were subjected to fracture by shear loading in a universal testing machine at a uniform crosshead speed of 0.05 mm per minute and expressed as MPa. Statistical analysis was performed using the Student t test (alpha = .05). The mode of failure was noted after a visual examination using a light microscope under x30 magnification. Failures were recorded as adhesive, cohesive or mixed, and statistical analysis was performed using a chi-square of homogeneity (alpha = .05). RESULTS: A significantly higher shear bond strength was found for the 3-step disinfection group (mean shear bond strength, 25.3 +/- 4.6 MPa) compared to the control group (mean shear bond strength, 20.5 +/- 3.4 MPa) (P < .0001). Most failures were adhesive for the control group, but the fracture modes were evenly divided for the 3-step disinfection protocol group. A chi-square test of homogeneity showed a value of 12.3, df = 2, P = .0012. CONCLUSIONS: The 3-step disinfection technique group showed a significantly stronger dentin shear bond strength compared to the conventional bonding technique without disinfection.

Comparative tensile strengths of preceramic and postceramic solder connectors using high-palladium alloy.

STATEMENT OF PROBLEM: It is not known whether different high-palladium alloys of similar composition possess comparable tensile strength properties associated with connector soldering. PURPOSE: The purpose of this study was to evaluate the tensile strength properties of 2 high-palladium alloys on soldered connectors under simulated pre-ceramic and post-ceramic soldering conditions. MATERIAL AND METHODS: Eighty cylindrical castings were fabricated (Rx Naturelle Plus alloy and Option alloy). The 40 castings for each alloy were subdivided into 2 groups of 20 each. In the first group, castings for each alloy were randomly paired and soldered with presolder (SMG2) to produce 10 preceramic test connector specimens for each alloy. In the second group, castings were similarly paired and soldered with postsolder (490 fine) to produce 10 postceramic test connector specimens for each alloy. Each soldered connector was subjected to tensile force until failure in a universal testing machine. Statistical analysis using a Wilcoxon rank sums test was performed (alpha=.05) RESULTS: No significant difference was found between the mean tensile failure stress for Rx Naturelle Plus preceramic solder (344.7 +/- 77.6 MPa) compared to Option preceramic solder (411.5 +/- 112.8 MPa) (P =.1202). However, the mean tensile failure stress for Rx Naturelle Plus postceramic solder (260.8 +/- 223.7 MPa) was significantly lower than the Option postceramic solder (312.6 +/- 120.8 MPa) (P =.0407). Not only did Rx Naturelle Plus postceramic solder connectors show evidence of lower strength, but also an increased variation among specimens. CONCLUSIONS: Rx Naturelle Plus solder connectors provided better strength with the preceramic as opposed with the postceramic connectors. For postsolder connectors, Rx Naturelle Plus alloy had less acceptable strength and a wider variation, suggesting it is more technique sensitive than Option alloy connectors.

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.