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:YVO 4 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 ( 3.5 Ti) to assess rabbit bone responses; the other a 1.0 mm diameter and 4.5 mm length ( 1.0 Ti) to assess rat gingival connective tissue responses. Laser-treated titanium implants, a 3.5 Laser-Ti and 1.0 Laser-Ti, were obtained by defocus irradiation. Collagen immobilized 1.0Laser-Ti ( 1.0 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 3.5 implants were implanted into the bone defects of rabbits to evaluate bone responses and 1.0 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.

Surrounding Tissue Response to Surface-Treated Zirconia Implants

“…The zirconia implants were placed according to previously described methods [44,48]. In a previous study, screw-type or cylinder-type titanium implants were inserted into the sockets of the maxillary molars of rats.…”

“…The implants were inserted into the sockets of the extracted maxillary teeth of rats, as described by earlier reports [44,48]. Surgery was conducted under general anesthesia administered by an intraperitoneal injection of ketamine hydrochloride (47 mg/kg, Daiichi Sankyo Propharma Co., Ltd. Tokyo, japan) and medetomidine hydrochloride (0.4 mg/kg, Nippon Zenyaku Kogyo Co., Ltd. Fukushima Japan).…”

“…Some surface modifications to titanium implants reportedly improved the soft tissue attachment. Microgroove formation by laser treatment is a well-established technique [41][42][43][44][45]. Moreover, surface modification with titanium binding peptides, mesh structures, collagen nanofibers, and magnesium-doping were reported [46][47][48][49].…”

Cortical bone response toward nanosecond-pulsed laser-treated zirconia implant surfaces

“…The attachment of gingival connective tissue to implant materials is unsatisfactory compared with its tight bonding to bone. Fukayo et al 17) evaluated the attachment of gingival connective tissue to nanosecondpulsed laser-treated titanium implants in the rat maxilla. Polarized light microscopic observation revealed perpendicular rod-like attachments of gingival collagen fibers on the laser-treated titanium implant surface.…”

“…Nanosecond-pulse laser irradiation can alter not only the surface morphology and roughness but also the condition of the titanium oxide layer by heat input, resulting in better cytocompatibility 15,16) . Fukayo et al 17) evaluated tissue response towards nanosecondpulsed laser-treated titanium after implantation into the tibiae of rabbits or the extracted sockets of rat maxillary molars. They found that nanosecond-pulsed laser treatment resulted in improved bone responses and attachment of gingival connective tissue.…”