Removal torques of conical, tapered implant abutments: the effects of anodization and reduction of surface area.

PURPOSE To examine the effects of anodization (surface coating) and reduction of internal Morse taper surface area on the reversal torque values of Straumann ITI dental implants and abutments. MATERIALS AND METHODS Eighty ITI solid screw implants were mated with corresponding 5.5-mm solid abutments. The assemblies were divided into 4 test groups of 20 specimens. All abutments were torque tightened into the implant to 35 Ncm. Half of the abutments were anodized and half were in their as-machined state. Each of these 2 groups included half of the implants with the standard internal Morse taper configuration and half with the synOcta (Straumann USA, Waltham, MA) internal positioning interface (indexed). Torque removal testing was then performed on the assemblies. The 4 groups were compared statistically to examine the effect of the 2 variables (anodization and reduction in surface area). Scheffe's test for multiple comparisons was used to compare groups at an adjusted significance level of < or = .05. RESULTS Torque removal of all specimens revealed that the indexed implant with the non-anodized abutment demonstrated superior removal torque. DISCUSSION The indexed and standard implants with anodized abutments, and the standard implant with the non-anodized abutment had lower reversal torque values. CONCLUSION The addition of the indexed internal surface to the ITI implant did not have deleterious effect on the resistance to loosening of standard solid abutments.