Resonance frequency analysis of dental implants after laser therapy

Abstract

Background: The importance of primary stability in implant placement for long-term success is well known in the literature. The resonance frequency analysis technique has extensively been used in experimental and clinical research for the last 10 years, for assessing primary stability. The benefits of low-level laser therapy in bone tissue are already consolidated in the literature, however, little is known about its benefits on improvement of stability of dental implants. Aim: The aim of this randomdouble blind clinical study was to investigate whether stability of titanium implants can be enhanced by low-level laser therapy during the osseointegration process when measured by means of resonance frequency analysis. Methods: Thirty implants (n¼30) were placed in the posterior region of partially edentulous mandible of eight adult patients, after following several inclusion criteria and were distributed bilaterally in agreement with the prosthetic requirement. The implants on the experimental side were randomly submitted to low-level laser therapy (830 nm, 86mW, 92.1 J/cm2, 2.57 J, 3 s/ point, at 20 points), and on the control side the laser irradiation was only simulated. The first irradiation was performed in the immediate postoperative period, and it was repeated every 48 h in the first 14 days. The initial implant stability quotient of the implants was measured by means of resonance frequency analyzer (Osstells). New implant stability quotient measurements were made after 10 days, 3, 6, 9 and 12 weeks. ANOVA for repeated measurements and Bonferroni test were used to assess statistically significant differences. Results: The initial implant stability quotient values ranged from 65 to 84, with a mean of 76. The irradiated side showed significant drop in stability from the 10th day until the sixth week only (P¼0.028), and presenting a gradual increase from the sixth to the 12th week. In the control side, the mean implant stability quotient increased up to the third week, decreased in the sixth week, and then began to grow again. The highest stability values were observed in the 10th day in the irradiated group, and the lowest in the sixth week in both groups. No statistical differences were detected among the ISQ means in the two groups for each of the six times observation. Conclusions and clinical implications: No evidence was found of any effect of low-level laser therapy on implants’ stability when measured by resonance frequency analysis. Because high primary stability and good bone quality are of major relevancy for a rigid bone–implant interface, additional low-level laser therapy under these conditions may have little impact macroscopically. Further researches under different bone conditions are necessary for a better understanding of the occurrences at bone/implant interface.