Measurement of the dimensions and abutment rotational freedom of gold-machined 3i UCLA-type abutments in the as-received condition, after casting with a noble metal alloy and porcelain firing.

STATEMENT OF PROBLEM: Laboratory processing of implant-supported prostheses may alter the surface of the abutment in contact with the implant head and thus the interface fit.
PURPOSE: This study assessed changes at the implant interface of gold-machined UCLA abutments after casting and porcelain baking in the case of single-tooth restorations.
MATERIAL AND METHODS: The depth (d) and width (w) of the hexagonal portion of the abutment, the apical diameter (D) of the abutment, and the abutment rotational freedom (R) were assessed for 30 gold-machined UCLA abutments before casting procedures (time 0), after casting with a noble metal alloy (time 1), and after the addition of porcelain (time 2) to detect any eventual fitting change in the abutments on the top of the implant hexagon.
RESULTS: No significant differences relative to all study parameters (d, w, D, and R) were observed between times 0, 1, and 2 (P=.576).
CONCLUSION: The results of this investigation suggest that, if all laboratory steps are observed carefully, changes at the implant interface of gold-machined UCLA abutments do not occur.