Re-Establishment of the Atomic Composition and the Oxide Structure of Contaminated Titanium Surfaces by Means of Carbon Dioxide Laser and Hydrogen Peroxide: zy An In Vitro Study Jaiifar Mouhyi, DDS, PhD;*t Lars Sennerby, DDS, PhD;** Ann Wennerberg, DDS, PhD;* Pierre Louette, PhD;' Nicolas Dourov, MD, PhD;# Jack van Reck, DDS, MD, PhD*t zyx ABSTRACT zyxwvutsrqp Background: In clinical situations with peri-implant bone resorption, re-integration of the exposed implant surface is sometimes preferable, which requires a clean surface. Previous investigations have shown that cleaning of contaminated titanium surfaces using chemical and abrasive methods is difficult. Purpose: The aim of this investigation was to evaluate the efficacy of different combinations of chemical and physical methods (citric acid, hydrogen peroxide, and carbon dioxide [COz] laser irradiation) for removal of contaminants and subsequent reconstruction of the surface oxide of intraorally contaminated titanium foils. Materials and Methods: Commercially pure titanium foils zyxwvu (99.6%, 5 zyxwv x 5 mm in size) were contaminated by placement on dentures in volunteering patients, simulating a peri-implantitis situation. The contaminated foils and clean control foils were treated by seven and zyxwvuts six combinations of citric acid, hydrogen peroxide, and C02 laser irradiation, respectively. The effect of the cleaning procedures was evaluated by x-ray photoelectron spectroscopy (US) and scanning electron microscopy (SEM). Results: The initial elemental composition of the contaminated foils was 70% carbon (C), 20% oxygen (0), 10% nitro- gen (N), and only traces of titanium (Ti) (< 1%). One treatment proved to be more effective than the others: irradiations by 5-second cycles of superpulsed C02 laser at a power of 7 W, 10-millisecond pulse width, and with an 80-Hz frequency on a wet surface, followed by repeated application of supersaturated citric acid for 30 seconds, each time followed by rins- ing with ultrapure water until all tissue remnants had been removed. Finally, hydrogen peroxide of 10-mM concentration was added to the implant surface and evaporated by C02 laser at the same settings. This treatment protocol resulted in 10% Ti, 45% 0, 41% C, and 2 to 3% N, a composition comparable to that of unused foils: 9% Ti, 40% 0, 48% C, and traces of N and chlorine (CI). X-ray photoelectron spectroscopy profiles showed that the thickness of the surface oxide was restored and even augmented with this protocol for treatment of contaminated titanium. Conclusion: A combination of citric acid, hydrogen peroxide, and COz laser irradiation seems to be effective for clean- ing and reestablishment of the atomic composition and oxide structure of contaminated titanium surfaces. KEY WORDS: citric acid, COz laser, decontamination, peri-implantitis, peroxide, surface analysis, titanium implants, x-ray photoelectron spectroscopy zyxwvutsrq (XPS) *Department of Oral and Maxillofacial Surgery, St. Pierre University vhe oxide surface energy level of commerciallv Dure z v, , L Hospital, Brussels, Belgium; +Schoolof Medicine, Free University of Brussels (ULB), Brussels, Belgium; *Department of Biomateriald Handicap Research, Institute for Surgical Sciences, University of Gote- 1 titanium Ti) is high, which facilitates adsorp- Of biomolecules and, Possibly, subsequent Y borg, Goteborg, Sweden; 5Brhemark Clinic, Public Health Service, City of Goteborg, Sweden; 'Laboratoire interdisciplinaire de spectroscopie electroniqueInstiute for Studies in Interface Sciences, Facultks Universi- taires de zyxwvutsrq Namur, Namur, Belgium; 'Department of Pathology and Elec- tronic Microscopy, School of Medicine (ULB), Brussels, Belgium Reprint requests: Jaalfar Mouhyi, DDS, PhD, HBpital Universitaire St. Pierre, Service de Chirurgie Stomatologique et Maxillo-faciale, 129, Boulevard de Waterloo, B-1000 Brussels, Belgium 02000 BC Decker Inc attachment.' Any contamination, even in a thin layer, diminishes the surface energy significant]y, which is believed to have negative effects on the adhesion capac- ity of osseous cells and bone tissue to titanium.2 For example, the hydrogen bondings between Ti02 and the hydroxyl groups of glycoproteins are radically disturbed by ~ontamination.~ Inorganic contaminants can also compromise the biocompatibility of an implant as a 190