Photobiomodulation by a 635nm Diode Laser on Peri-Implant Bone: Primary and Secondary Stability and Bone Density Analysis—A Randomized Clinical Trial

INTRODUCTION: Various procedures in dental implantology are performed to enhance the bone healing process and implant stability. One of these methods can be a low-level laser therapy (LLLT). OBJECTIVES: The aim of our study was to evaluate the stabilization (primary and secondary) and bone density in peri-implant zone after LLLT protocol using a 635 nm diode laser. MATERIAL AND METHODS: The research included 40 implants placed in the posterior region of a mandible in 24 patients (8 women and 16 man; age: 46.7 ± 8.7 years). The patients were randomly divided into 2 groups G1 (n=12, 18 implants) and G2 (n=12, 22 implants) according to the treatment procedure; G1 (test): 635 nm laser, with handpiece diameter: 8mm, output power: 100mW, spot area: 0.5024cm(2), average power density: 199.04mW/cm(2), continuous mode, dose: 4J per point (8J/cm(2)), time: 40 sec per point, 2 points (irradiation on a buccal and a lingual side of the alveolus/implant), and total energy per session 8J; G2 (control): no laser irradiation. The G1 (test) group's implants were irradiated according to the following protocol: 1 day before surgery, immediately after the surgery and 2, 4, 7, and 14 days after. The total energy after all therapeutic sessions was 48J. The implants stability was measured employing a Periotest device (Periotest Test Value: PTV) (measured immediately after the surgery, 7 days, 2 weeks, 4 weeks, and 2 and 3 months after the surgery) and the bone density using cone-beam computed tomography (grayscale value) (measured immediately after the surgery, 4 weeks and 12 weeks after the treatment). RESULTS: The average implant stability at different time points showed lower PTV value (higher stability) at 2(nd) and 4(th) week after 635 nm laser irradiation (G1) compared with a control (G2) group (p<0.01). The secondary stability of the implants after 12 weeks observation was not significantly higher for the laser group in contrast to none-irradiated implants (p>0.05). The mean grayscale value at the apical, middle, and cervical level of the titanium implants showed the reduction of pixel grayscale value after 2 weeks and was lower for the G1 group in contrast to the G2 group (p<0.01). The value of grayscale after 12 weeks was significantly higher at the middle and apical level of the implants in the G1group in contrast to the G2 group (p<0.01). CONCLUSION: The application of the 635 nm diode laser enhanced secondary implant stability and bone density. However, to assess the impact of the LLLT on peri-implant bone with different bone densities, further well-controlled long-term trials on larger study groups are needed.