Using implant connectors to support clinical abrasion probes: a methodological study.

OBJECTIVES: To validate a procedure aimed at assessing the clinical wear rate of full crown veneering materials. To confirm its clinical applicability and alignment capacity in the ancillary profiling apparatus. To quantify the wear rate of a full crown veneering composite (Sinfony, 3M-ESPE) as compared to that of a ceramic (negative control) and an unfilled resin (positive control). METHODS: The technique consisted in utilizing implant supported crowns which were either screw-fastened to endosseous implants via ITI-Straumann Octa connectors or to an Octa analog on an x-y measuring table. After initial contour profiling, 14 crowns were placed in the mouths of seven patients. Six crowns were veneered with composite, four with ceramic and four with an unfilled resin. The crowns were removed at 3, 6, 9, 12, 15, 18 and 24 months and digitalized contour profiles were obtained. Contour profiling consisted in securing the restorations to the x-y table and assessing the z-coordinate using an LVDT stylus. At the end of the experimental period, loss of material was computed as the differences between the initial- and subsequent measurements. RESULTS: The total error of the method was estimated at +/-10 microm. The composite's annual wear rate was 75 microm/year, the ceramic wore at ca. 6 microm/year and the unfilled resin wore at 160 microm/year. Wear was unevenly distributed and concentrated on occlusal contact areas. SIGNIFICANCE: (1) A technique utilizing ITI-Straumann octagonal implant connectors is suitable for clinical use. (2) The veneering composite wears at a rate that is superior to ADA guidelines for composites intended for direct fillings.