Effects of an Erbium:Yttrium-Aluminum-Garnet Laser and Ultrasonic Scaler on Titanium Dioxide-Coated Titanium Surfaces Contaminated With Subgingival Plaque: An In Vitro Study to Assess Post-Treatment Biocompatibility With Osteogenic Cells.

Background: Effects of conventional ultrasonic scaler versus an erbium:yttrium-aluminum-garnet (Er:YAG) laser on titanium surfaces contaminated with subgingival plaque from patients with peri-implantitis are evaluated in terms of: 1) plaque and biocorroded titanium oxide coating removal; 2) surface change induction; and 3) residual biocompatibility toward osteoblasts.

Methods: Subgingival plaque-coated titanium disks with a moderately rough surface were fixed with ethanol and treated with an ultrasonic scaler (metal tip) or Er:YAG laser (20.3 or 38.2 J/cm) in non-contact mode. Fluorescent detection of residual plaque was performed. Disk surface morphology was evaluated by scanning electron microscopy. Viability, attachment, proliferation, and differentiation of Saos-2 osteoblasts on new and treated disks were assayed by propidium iodide/DNA stain assay and confocal microscopic analysis of cytoskeleton, Ki67, expression of osteopontin and alkaline phosphatase, and formation of mineralized nodules.

Results: Both methods resulted in effective debridement of treated surfaces, the plaque area being reduced to 11.7% with the ultrasonic scaler and ≤0.03% with the Er:YAG laser (38.2 J/cm). Ultrasound-treated disks showed marked surface changes, incomplete removal of the titanium dioxide (TiO) layer, and scanty plaque aggregates, whereas the Er:YAG laser (38.2 J/cm) completely stripped away the plaque and TiO layer, leaving a micropitted surface. Both treatments maintained a good biocompatibility of surfaces to Saos-2 osteoblasts. Air-water cooling kept disk temperature below the critical threshold of 47°C.

Conclusion: This study shows that an ultrasonic scaler with metal tip is less efficient than high-energy Er:YAG irradiation to remove the plaque and TiO layer on anodized disks, although both procedures appear capable of restoring an adequate osseoconductivity of treated surfaces.