ABSTRACT
PURPOSE: One-size implant-abutment (OSIA) connection systems have been developed for simplicity of clinical use and for a range of implant diameters. The aim of this in vitro study was to investigate the rotational load fatigue performance of different implant diameters and abutment platforms of an OSIA connection system. METHODOLOGY: Narrow, regular and wide diameter implants were tested with Regular Base (RB/WB) abutments of an OSIA system (Straumann. BLX). Wide diameter implants were also tested with Wide Base (WB) abutments. This resulted in 4 test groups (n=5): N-RB/WB (Narrow, 3.5mm, RB/WB abutment), R-RB/WB (Regular, 4.0mm, RB/WB abutment), W-RB/WB (Wide, 5.0mm, RB/WB abutment) and W-WB (Wide, 5.0mm, WB abutment). A rotational load fatigue machine applied a sinusoidally varying stress at an angle of 45o, producing an effective bending moment of 35Ncm at a frequency of 10 Hz in air at 20 oC. The number of cycles to failure was recorded. Results were evaluated using ANOVA. Failed specimens were examined with SEM to evaluate the failure mode. Pristine specimens were sectioned to examine the implant-abutment connection. RESULTS: All specimens in the 3 test groups with RB/WB abutments failed within the range of 558,750 cycles to 4,497,619 cycles, while the W-WB test group reached the upper limit of 5 million cycles without failure. Significant difference was found between abutment platforms (P < .001). There were no significant differences found for implant diameters (P =.857). However, with increasing implant diameter, implant fracture was less common and the location of failure was more coronal and consistently at the level of the implant platform for the abutment, and at the screw neck. CONCLUSIONS: For wide diameter implants, WB abutments exhibited a superior fatigue performance than RB/WB abutments, and would be preferred in situations of high mechanical risk. Increasing implant diameter, when used with RB/WB abutments, did not improve fatigue performance due to the one-size prosthetic connection, but failures were less catastrophic, and coronally located, which may be advantageous in managing failures.
ABSTRACT
STATEMENT OF PROBLEM: The minimum amount of resistance form required for the success of a clinical crown is unknown.There is little information on the fatigue performance of complete coverage restorations on natural tooth preparations cemented with different luting cements. PURPOSE: The purpose of this study was to evaluate the effect of tooth preparation height and luting agent on resistance form using unidirectional load fatigue testing. For a given tooth preparation with a clinically relevant total occlusal convergence (TOC), the adequacy of resistance form was investigated. MATERIAL AND METHODS: Sixty-four human maxillary premolars were prepared with occlusal-cervical dimensions of 2, 3,4, or 5 mm and a TOC of 20 degrees. Complete metal crowns were cemented using either zinc phosphate cement (HY Bond;ZP groups) or resin cement (Panavia F; PF groups). Cyclic load fatigue testing was done with an applied load of 6.0 kg at 2.6 Hz. Load cycles to preliminary failure were detected with a strain gauge at the palatal crown-tooth interface. Results were subjected to the Kruskal-Wallis test and the Wilcoxon post-hoc rank sum test (alpha=.05). RESULTS: Groups ZP4, ZP5, PF2, PF3, PF4, and PF5 had the highest mean number of cycles to preliminary failure,while group ZP2 had the lowest mean number of cycles to failure. Group ZP2 was significantly different (P<.001) from all other test groups for the number of cycles to failure. CONCLUSIONS: For the 2- and 3-mm preparation height groups, zinc phosphate cement exhibited a poorer fatigue performance compared to Panavia F. There was no significant difference in the number of cycles to failure for groups ZP4,ZP5, PF2, PF3, PF4, and PF5. For both cements, the number of cycles to failure increased with increasing resistance length. (J Prosthet Dent 2009;102:155-164)
