Characterization of treated porcelain surfaces via dynamic contact angle analysis

Successful porcelain repair requires conditioning of porcelain surfaces. Conditioning is intended lo facilitate wetting by repair materials and improve interfacial bonding. The objective of this investigation was to determine the eftects of selected surface treatments upon the wettability of a representative feldspatilic porcelain. 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 regimens: (1) control (no treatment); (2) airborne particle abrasion using 50 µm aluminum oxide; (3) etching with ammonium bifluoride gel; (4) etching with acidulated phosphate fluoride gel; and (5) etching witb hydroflLonc acid gel. Following treatment, specimens were cleansed and dried. Advancing contact angles were quantified using dynamic contact angie analysis. Mean values 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 fluoride, 24.9 ± 1.7; and hydrofluoric acid, 16.5 ± 1.2. Significant differences were found between and 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 in surface area may correspond to enhanced resinporcelain bonding.