Numerical analysis of thermal damage by changing irradiation angle for peri-implantitis using photothermal therapy

Many people use various methods to treat inflammation. Inflammation treatment is primarily and widely managed with medications, but there are ongoing efforts to use lasers for treating conditions such as peri-implantitis. Recent studies have been conducted using various lasers, such as diodes, Er:YAG, and CO₂ lasers, to sterilize and purify implant surfaces. In this study, the therapeutic effects of photothermal therapy, a laser treatment method for inflammation around implants (peri-implantitis), were analyzed through numerical analysis based on the theory of heat transfer. Peri-implantitis locates between the gingiva and implant, requiring the laser to be angled during irradiation. The numerical analysis conditions were selected as follows: laser power in the range of 0.0–4.0 W, laser irradiation angles between 50° and 80°, and laser irradiation times of 100–500 s. The Arrhenius damage integral was used to quantitatively verify the therapeutic effects of photothermal therapy (irreversible inflammatory damage). Finally, the optimal conditions for each laser irradiation angle were derived using the Arrhenius thermal damage ratio, which indicates the proportion of the total inflammatory volume where the Arrhenius damage integral exceeds 1.