Characterization of Treated Porcelain Surfaces Via Dynamic Contact Angle Analysis

Successful porcelain repair requires conditioning of porcelain surfaces. Conditioning is intended to facilitate wetting by repair materials and improve interfacial bonding. The objective of this investigation was to determine the effects of selected surface treatments upon the wettability of a representative feldspathic procelain. Dynamic contact angle analysis and scanning electron microscopy were used to characterize the effects of such treatments. Standardized porcelain specimens were subjected to the following five treatment regiments: (1) control (no treatment); (2) airborne particle abrasion using 50 um aluminum oxide; (3) etching with ammonium bifluoride gel; (4) etching with acidulated phosphate fluoride gel; and (5) etching with hydrofluoric acid gel. Following treatment, specimens were cleansed and dried. Advancing contact angles were quantified using dynamic contact angle analysis. Mean falues and 95% confidence intervals were (in degrees): control, 63.8±2.7; ammonium bifluoride, 39.4 ±2.0; airborne particle abrading, 29.1±2.9; acidulated phosphate flouride, 24.9 ± 1.7; and hyudrofluoric acid 16.5 ± 1.2. Significant differences were found between all treatment groups (P=.05). Subsequent scanning electron microscopy examination of treated surfaces indicated lesser contact angles were associated with surfaces displaying deeper and wider grooves. Apparently, the resultant increase in surface area produces increased wettability. It is inferred that an increase insurface area may correspond to enhanced resin porcelain bonding.