Evaluation of the Surface Roughness and Morphologic Features of Y-TZP Ceramics after Different Surface Treatments Andrea N. Cavalcanti, D.D.S., M.S., Ph.D., 1 Peter Pilecki, B.Sc., 2 Richard Mark Foxton, B.D.S., Ph.D., MFDS, RCA(Ed), FHEA., 3 Timothy F. Watson, B.D.S., Ph.D., F.D.S., RCS (Eng), 2 Marcelo Tavares Oliveira, D.D.S., M.S., Ph.D., 1 Marcelo Gianinni, M.S., Ph.D., 1 and Giselle M. Marchi, D.D.S., M.S., Ph.D. 1 Abstract Objective: This study aimed to investigate the effect of different energy intensities of the Er:YAG laser and of air abrasion with Al 2 O 3 particles on the surface roughness and morphologic characteristics of yttrium-stabilized tetragonal zirconia (Y-TZP) ceramics. Background Data: Surface roughness enhances the micromechanical in- terlocking of luting agents to ceramic surfaces. However, the most appropriate surface treatment for Y-TZP ceramics has yet to be determined. Materials and Methods: Two Y-TZP materials were evaluated: Cercon Smart Ceramics and Procera Zirconia. Thirty plates from each ceramic material were randomly divided into five groups according to the surface treatment received (none [control], air abrasion, or irradiation with the Er:YAG laser at three different energy intensities [200, 400, or 600 mJ]). After the surface treatments, the ceramic plates were gold-coated and their surface roughness (Ra, mm) was measured using confocal microscopy. For each ceramic system, the surface roughness was analyzed through two-way ANOVA=Tukey’s test, with a 5% sig- nificance level. Changes in the morphological characteristics of the ceramics were examined through light and scanning electron microscopy. Results: For both zirconia-based materials, irradiation with 400 mJ or 600 mJ increased surface roughness and provided significant morphological changes. Air-abraded Cercon surfaces were rougher compared to the ones irradiated with 200 mJ of laser energy, whereas Procera surfaces irradiated with 200 mJ were rougher than the air-abraded ones. Conclusions: Higher laser power settings (400 and 600 mJ) cause excessive material deterioration, making them unsuitable as surface treatments for zirconia surfaces. Irradiation with 200 mJ provides mild surface alterations, with intermediary features between the effects of air abrasion and higher laser intensities. Introduction A durable and stable bond between luting cements and ceramics is fundamental for the long-term performance of all ceramic indirect restorations. Resin cements have some advantages over other luting materials such as zinc- phosphate cements and glass-ionomer cements. These include improved marginal seal, good retention, and adequate aes- thetic characteristics. 1,2 However, one of the key mechanisms for an adequate bond between resin cement and ceramic is the micromechanical attachment. 2–4 Roughening the inner sur- faces of ceramic restorations increases the area available for the penetration and in-situ polymerization of resin-based materials, enhancing the mechanical bond. Etching with 5–10% hydrofluoric acid is a well-suited sur- face treatment method for silica-based ceramics. 2,3 Acid etch- ing selectively removes the glassy matrix of some ceramic systems, exposing the crystalline structures, resulting in sub- stance loss and an increase in surface roughness. 2,5 However, high-strength ceramic materials, such as yttrium-stabilized tetragonal zirconia (Y-TZP) ceramics, are not suitable for acid etching since they do not have the glassy phase. 5–8 For this 1 Department of Restorative Dentistry, Piracicaba Dental School, UNICAMP, Piracicaba, Sa ˜ o Paulo, Brazil, 2 Biomaterials, Biomimetics and Biophotonics Research Group, and 3 Department of Conservative Dentistry, King’s College London, King’s College London Dental Institute, London, U.K. Photomedicine and Laser Surgery Volume 27, Number 3, 2009 ª Mary Ann Liebert, Inc. Pp. 473–479 DOI: 10.1089=pho.2008.2293 473