Survey of partial removable dental prosthesis (partial RDP) types in a distinct patient population.

STATEMENT OF PROBLEM: Current demographic information on the number and types of removable partial dentures is lacking in the prosthodontic literature. PURPOSE: This study was designed to investigate patterns of tooth loss in patients receiving removable partial dentures (RPDs) in eastern Wisconsin. MATERIAL AND METHODS: Digital images (1502) of casts at 5 dental laboratories in eastern Wisconsin were collected. Any prescription requesting fabrication of a removable partial denture was photographed twice. The first photograph was made immediately upon arrival at the laboratory, while the second photograph was made immediately before being returned to the prescribing dentist for the first time. A calibrated investigator analyzed all the photographs for Kennedy Classification, type of RPD, major connector, and other details. Data were analyzed with descriptive statistics. Fisher's exact test was used to confirm repeatability. RESULTS: Kennedy Class I was the most common RPD with a frequency of 38.4%. More than 40% of prescriptions had no design input from the dentist. One in 3 RPDs used acrylic resin or flexible frameworks. One in 5 RPDs had no rests. The horseshoe major connector was the most common maxillary major connector, while the lingual plate was the most common in the mandible. CONCLUSIONS: RPDs remain a common prosthodontic treatment in this region. Non-metal RPD frameworks are a common treatment type and rarely include rests. These data indicate a changing partially edentulous patient population and a variable commitment to standard levels of prosthodontic care.

Corrosion behavior of shape memory, superelastic, and nonsuperelastic nickel-titanium-based orthodontic wires at various temperatures.

OBJECTIVE: Nickel-titanium orthodontic wires have various temperature-dependent phases. The purpose of this study was to investigate temperature-dependent corrosion characteristics of shape memory, superelastic, and nonsuperelastic orthodontic wires. METHODS: Four orthodontic wires were investigated: 27 and 40 degrees C copper Ni-Ti (superelastic and shape memory, respectively), superelastic Ni-Ti, and nonsuperelastic Nitinol Classic. Differential scanning calorimetry (DSC) was used to confirm phase/temperature behavior of the wires. Sectioned halves of as-received archwires were assessed electrochemically in artificial saliva at 5, 24, 37, and 45 degrees C. Open circuit potential (OCP) was monitored for 2h followed by polarization resistance and cyclic polarization tests. RESULTS: DSC results showed Nitinol was primarily martensitic-stable whereas NiTi, 27 degrees C CuNiTi, and 40 degrees C CuNiTi possessed austenite-finish temperatures of approximately 19, 21, and 38 degrees C. The OCP of the CuNiTi wires was significantly greater than NiTi and Nitinol but no apparent trend in values was apparent with regard to temperature or phases present. Corrosion current density (i(corr)) increased with temperature for all wires, but not all were equally influenced. The two lowest austenite-finish temperature wires (27 degrees C CuNiTi and NiTi) approximately tripled in i(corr) from 37 to 45 degrees C. Greater incidence of pitting was observed in the CuNiTi wires. SIGNIFICANCE: This study showed the corrosion rate of various nickel-titanium wires increase with temperature and different phases present may influence corrosion rate trends.