Diode Laser Light Scattering and Temperature Changes Due to Anesthesia Injection in Bovine Tongue Mucosa

Diode lasers are used in periodontal therapy. Parameters such as wavelength and application mode can affect the laser/tissue interactions, quality of incision, and final outcomes. This study set out to assess the temperature changes in tissue when diode lasers are used for incisions on tissues injected with local anesthetics. Incisions were made on the surface of bovine tongue parallel to the tongue axis (ex vivo). The tissue was divided into three groups (lidocaine, saline, and a control group with no infiltration). Irradiation was performed with 810 and 980 nm diode lasers. Trials were further divided using noninitiated and initiated tips. A microprobe thermocouple was placed to evaluate the temperature changes. Linear mixed-model with Tukey adjustment was used to make comparisons and p < 0.05 was denoted as statistically significant. The overall group comparisons reveal that the control group mean rise in temperature is lower than both the lidocaine group (p < 0.0001) and the saline group (p < 0.0001). When combining the data in and across each group, the average temperature rise that occurred for incisions made with initiated tips was significantly lower than incisions made with noninitiated tips (p < 0.0001). Combining the data of tip initiation shows that incisions made with a 980 nm laser produced lower temperature changes, than incisions made with an 810 nm laser (p < 0.0001). Infiltration of water-based liquids, such as local anesthetics or saline, causes an increase in tissue temperature during irradiation, especially when noninitiated tips are used. In addition, temperature significantly rises with the use of the 810 compared with the 980 nm diode laser. Therefore, to avoid photothermal damage to the tissue, the use of initiated tips is encouraged and local anesthetics in conjunction with 810 nm diode lasers should be minimized.