Effects of Er:YAG laser irradiation of different titanium surfaces on osteoblast response

Christian Wehner,Markus Laky,Christian Behm,Andreas Moritz,Oleh Andrukhov,Hassan Ali Shokoohi-Tabrizi,Xiaohui Rausch-Fan

doi:10.1007/s10856-021-06493-y

Abstract

The aim of this in vitro study was to evaluate the effects of erbium-doped yttrium aluminum garnet (Er:YAG) laser irradiation on titanium surface topography and the proliferation and differentiation of osteoblasts using standard clinical treatment settings. Er:YAG laser irradiation at two levels ((1): 160 mJ, pulse at 20 Hz; (2): 80 mJ, pulse at 20 Hz) was applied to moderately rough and smooth titanium disks before MG-63 osteoblast-like cells were cultured on these surfaces. Titanium surface and cell morphology were observed by scanning electron microscopy. Cell proliferation/viability was measured by CCK-8 test. Gene expression of alkaline phosphatase (ALP), osteocalcin (OC), osteoprotegerin (OPG), receptor activator of nuclear factor kappa-B ligand (RANKL), and collagen type 1 was measured by qPCR, and OPG and OC protein production was determined by enzyme-linked immunosorbent assay. Treatment with Er:YAG laser at 160 mJ/20 Hz markedly caused heat-induced fusion of titanium and cell condensation on moderately rough surfaces, but not in smooth surfaces. MG-63 proliferation/viability decreased after 5 days in moderately rough surfaces. The expression of ALP, OC, OPG, and collagen type 1 was unaffected by laser treatment at 160 mJ/20. Laser irradiation at 80 mJ/20 Hz enhanced RANKL gene expression after 5 days in moderately rough surfaces. Study results suggest that Er:YAG laser irradiation at clinically relevant setting has no essential effect on osteogenic gene and protein expression of osteoblasts. However, surface structure, cell attachment, and proliferation are influenced by both treatment protocols, which implies that caution should be taken in the clinical treatment of peri-implant diseases when Er:YAG laser is used.

Highlights

Endosseous implants nowadays represent a standard treatment procedure in clinical practice, demonstrating high long-term success rates [1, 2]
At the same settings (SLA I), MG-63 cells appeared condensed in the core area affected by laser irradiation, which can be observed in SLA II to a lower extent (Fig. 1)
There were no significant differences in the proliferation/viability between untreated surfaces and tissue culture plastic (TCP) group

Summary

Introduction

Endosseous implants nowadays represent a standard treatment procedure in clinical practice, demonstrating high long-term success rates [1, 2]. Titanium has shown longterm evidence as a safe material for dental implants and still is considered gold standard. In terms of tissue biocompatibility, surface topography is considered as a critical factor influencing the osseointegration process following implant 22 Page 2 of 10. Preclinical studies have demonstrated that titanium implants with moderately rough surfaces exhibit both higher bone-to-implant contact and removal torque compared to smooth surface implants [4]. Despite positive effects on osseointegration, moderately rough surfaces promote bacterial adherence and facilitate plaque accumulation, which is considered the primary etiologic agent for peri-implant diseases [7, 8]

Methods

Results

Discussion

Conclusion