In vitro investigation of the wear of human enamel by dental porcelain

Statement of problem. Metal ceramic systems are advocated when both estheti cs and strength are required. A major drawback to many porcelains is their wear and destruction of opposing natural dentition. Purpose. This study evaluated the wear of enamel opposing 1 traditional and 2 recently introduced low-fusing feldspathic dental porcelains. Material and methods. Six blocks of Ceramco II, Finesse, and Omega 900 feld spathic porcelain materials were fabricated and fired according to manufact urer recommendations. Porcelain blocks were polished through 0.25 mu m diam ond polishing paste. Thirty-six enamel specimens were obtained and milled t o a 2 mm (+0.5 mm) diameter. Enamel specimens were attached to an offset ca m motor operating at 60 Hz. Enamel specimens were in constant contact with the stationary porcelain blocks under a load of 600 g and traversed a dista nce of 8 mm. Diameter and height of enamel specimens were measured at times of 0, 6, 12, 24, and 48 hours and subsequent determination of enamel volum e loss recorded. Profilometric surface roughness of the ceramic blocks was also measured for the corresponding times. Results. Statistical analysis revealed that both Finesse and Omega 900 feld spathic porcelains caused significantly less enamel volume loss when compar ed with Ceramco II porcelain at all time intervals. Surface roughness revea led no consistent significant differences among porcelains. Conclusion. Both Finesse and Omega 900 porcelains were not as destructive t o human tooth structure as Ceramco II porcelain. These results suggest an a dvantage of the new, lower-fusing porcelains in conditions where natural de ntition wear is a concern.