Q-Switch Nd:YAG Laser-Assisted Decontamination of Implant Surface

Abstract

Peri-implantitis (PI) is an inflammatory disease of peri-implant tissues, it represents the most frequent complication of dental implants. Evidence revealed that microorganisms play the chief role in causing PI. The purpose of our study is to evaluate the cleaning of contaminated dental implant surfaces by means of the Q-switch Nd:YAG (Neodymium-doped Yttrium Aluminum Garnet) laser and an increase in temperature at lased implant surfaces during the cleaning process. Seventy-eight implants (titanium grade 4) were used (Euroteknika, Sallanches, France). Thirty-six sterile implants and forty-two contaminated implants were collected from failed clinical implants for different reasons, independent from the study. Thirty-six contaminated implants were partially irradiated by Q-switch Nd:YAG laser (1064 nm). Six other contaminated implants were used for temperature rise evaluation. All laser irradiations were calibrated by means of a powermetter in order to evaluate the effective delivered energy. The irradiation conditions delivered per pulse on the target were effectively: energy density per pulse of 0.597 J/cm², pick powers density of 56 mW/cm², 270 mW per pulse with a spot diameter of 2.4 mm, and with repetition rate of 10 Hz for pulse duration of 6 ns. Irradiation was performed during a total time of 2 s in a non-contact mode at a distance of 0.5 mm from implant surfaces. The parameters were chosen according to the results of a theoretical modeling calculation of the Nd:YAG laser fluency on implant surface. Evaluation of contaminants removal showed that the cleaning of the irradiated implant surfaces was statistically similar to those of sterile implants (p-value ≤ 0.05). SEM analysis confirmed that our parameters did not alter the lased surfaces. The increase in temperature generated at lased implant surfaces during cleaning was below 1 °C. According to our findings, Q-switch Nd:YAG laser with short pulse duration in nanoseconds is able to significantly clean contaminated implant surfaces. Irradiation parameters used in our study can be considered safe for periodontal tissue.

Keywords: biofilm; dental implant; peri-implantitis; titanium surfaces decontamination.

Figure 1

Increase in titanium surface temperature, $\Delta T\left(t\right)$, upon a single laser pulse radiation according to the parameters in Table 1. Inset: dimensionless function η(x) [21].

Figure 2

Remaining coverage of the contaminant after one laser shot as a function of the safety parameter (S_a) and of the laser pulse duration.

Figure 3

Setup for the assessment of the temperature increase measurements on a contaminated dental implant. The thermocouple probes placed in close contact with the apical region and at 1 mm from the irradiation area of implant surface.

Figure 4

Scanning Electron Microscope (SEM) view of the lased area of contaminated implant (group C + L). The surface showed a clean aspect without alteration, melting areas or cracks.

Figure 5

SEM view of the group S showing the relief and the roughness of the surfaces of a sterile implant.

Figure 6

SEM view of the unlased but contaminated implant surface (Group C) showed the contaminants totally covering the roughness and the relief of the implant surface.

Figure 7

Percentage of mean of carbon mass (percentage) on implant surfaces in the S, C and L groups.

Figure 8

An example of an Energy Dispersive X-ray (EDX) measurement showing the value of Carbone (mass percentage) on lased surface of the group C + L.