Avaliação térmica e histológica da incisão cirúrgica no freio lingual com lasers de diodo (450 nm e 980 nm) em modelo animal (ratos wistar)

Abstract

Thermal surgical instruments are widely used in soft tissue surgeries due to their ability to promote hemostasis and reduce the need for sutures; they are also indicated for lingual frenectomy. However, the effects of heating on the tissue and local tissue repair still raise questions. This two-stage study aimed to evaluate the thermal effects and tissue repair after incisions performed on the lingual frenulum using different instruments. In the first stage (ex vivo), 60 porcine tongues underwent incisions with Iris scissors, electrocautery, electronic scalpel, erbium laser (at different parameters), and high-power diode lasers (450 nm and 980 nm, at different parameters). Temperature was monitored via infrared thermography (FLIR C5), recording values during, at the end of, and 1 minute after the incisions. The lowest heating was observed in the scissors group (5.6 °C), while the highest averages were found in the 980 nm high-power diode laser (22.6 °C) and the 450 nm laser (16.7 °C); the latter showed the fastest cooling (13.6 °C within 1 minute). In the second stage, the instruments were selected based on the results of the first stage. Two high-power diode laser instruments in pulsed mode were chosen, featuring the same fiber tip type (600 micrometers diameter) but different wavelengths. This stage was conducted in vivo with 30 young pre-pubescent Wistar rats, distributed into three groups: scissors (control), 450 nm diode laser, and 980 nm diode laser, both in pulsed mode. Thermographic and histological analyses were performed in the immediate and postoperative periods (days 0 and 7). The 980 nm diode laser group presented one case of controlled bleeding during the procedure, while the 450 nm diode laser group presented no cases of bleeding. Although both showed similar clinical tissue repair results on the seventh day, the 450 nm laser group exhibited a smaller amount of disorganized, fibrotic-like collagen bundles compared to the 980 nm laser, appearing more similar to the surgical scissors group. Both thermal instruments presented similar clinical, thermal, and histological characteristics and can be safely employed for lingual frenulum incisions, showing similar heating and tissue repair patterns. It is expected that these results will aid in understanding the thermal and biological safety of these lasers in lingual frenulum surgery; however, further histological and clinical studies are necessary to confirm these findings.