Multiparametric evaluation of fitting accuracy for different combinations of implant-abutment coupling at marginal interface

Objectives. This study describes a method for the measurement of the marginal gap between abutment and prosthetic crown and analyses the influence of different variables influencing the fitting precision. Methods. The extent of marginal gap between titanium or dental abutment with different implant types composed of sintered titanium, milled titanium alloy, zirconia and translucent zirconia was evaluated. The gap at implant-abutment interface was analysed by optical stereomicroscope observation. To optimise measurement precision, samples were oriented with a specific inclination angle and properly stained to limit reflection phenomena. Captured images was processed by ImageJ virtual measuring instruments. The correlation between various factors including type of tooth (molar, canine), stump type (artificial, natural), prosthesis type (sintered titanium, titanium, zirconia and translucent zirconia), and gap type (proximal, distal) was statistically evaluated performing the study of variance (ANOVA). Results. There was a significant correlation between the type of abutment and the different materials used for implant on fitting accuracy. The variables type of tooth and gap type do not significantly correlate with the marginal gap size. Results of the ANOVA test demonstrated that the association titanium abutment and titanium implant represent the best fitting with a minimum level of marginal gap at the junction interface. Conclusions. The measurement of marginal gap with stereoscopic observation associated with the analysis of variance has been demonstrated to be a valuable method for marginal gap evaluation. This approach demonstrated that the best abutment-implant fitting is represented by the association between titanium abutment and titanium implant. This model could be used to perform preliminary evaluation in order to help the clinician to select the best match of components for prosthetic implant.