Bone and gingival connective tissue responses towards nanosecond-pulsed laser-treated titanium implants

Abstract

The aim of this study was to evaluate bone and gingival connective tissue responses towards nanosecond-pulsed laser-treated titanium implants. A Nd:YVO4 nanosecond-pulse laser with a defocus technique was used to modify the surfaces of two types of cylindrical titanium implants. One had a 3.5 mm diameter and 7.0 mm length (φ3.5 Ti) to assess rabbit bone responses; the other a 1.0 mm diameter and 4.5 mm length (φ1.0 Ti) to assess rat gingival connective tissue responses. Laser-treated titanium implants, a φ3.5 Laser-Ti and φ1.0 Laser-Ti, were obtained by defocus irradiation. Collagen immobilized φ1.0Laser-Ti (φ1.0 Coll/Laser-Ti) implants were obtained by a tresyl chloride-activated method. Laser-Ti surfaces had micro-scale roughened oxide layers and parallel arranged grooves. Sa (average roughness) and Sdr (interfacial area ratio) values of the Laser-Ti were significantly higher than those of Ti (titanium) implants (p<0.05). The φ3.5 implants were implanted into the bone defects of rabbits to evaluate bone responses and φ1.0 implants were implanted into the extracted sockets of rat maxilla to evaluate gingival connective tissue responses. After implantation periods, the specimens were excised and non-decalcified thin sections prepared to evaluate histological responses. After 12 weeks of implantation in the rabbit experiments, bone-to-implant contact for the Laser-Ti implants was significantly higher than for the Ti in both tibia and femoral condyle (p<0.05). Improved attachment of gingival connective tissue to the implant surface was observed for Laser-Ti and Coll/Laser-Ti in the rat maxilla. Polarized light microscopy showed perpendicular rod-like attachments of gingival collagen fibers on the Laser-Ti and Coll/ Laser-Ti implant surfaces. Ti implants had no discernible attachments with gingival connective tissue along the implant surface. In conclusion, nanosecond-pulsed laser treatment with a defocus technique produced roughened titanium surfaces with parallel grooves and micro-roughened asperities. Laser treatment of implants resulted in improved bone responses and attachment of gingival connective tissue.