Gingival temperature rise and tissue injury associated with diode laser-based versus LED curing protocols in a swine model.

OBJECTIVES: To measure in vivo gingival temperature rise (ΔT), peak temperature, and the incidence and probability of lesions in swine gingiva exposed to diode laser- and LED-based light-curing protocols. The protective effect of rubber dam isolation (RDI) was also assessed. METHODS: After Ethics Committee approval (23.000010496-0), 100 pigs were subjected to general anesthesia. In 50 pigs, a thermocouple probe (Thermes WFI, Physitemp) was inserted into the gingival sulcus to measure temperature (°C) before and after exposure to light from a conventional LED (EDC - Elipar DeepCure, Solventum) and a high-power ultrafast diode laser (ML - Monet, AMD Laser). Exposure protocols with different radiant exposure values were applied (EDC-5s, EDC-10s, EDC-20s; ML-1s, ML-3s), with or without RDI (n = 10). Gingival lesion incidence was assessed in the remaining animals. ΔT data were analyzed using nonparametric two-way ANOVA with Bonferroni post-hoc test. Logistic regression estimated odds ratios (95% confidence intervals) (α = 0.05). RESULTS: EDC-20s showed the highest ΔT values. ML-1s produced ΔT comparable to EDC-5s, whereas ML-3s did not differ from EDC-20s. RDI reduced ΔT in most groups. Lesion incidence was below 45% in most groups. Despite similar ΔT, ML-3s showed the highest lesion incidence and was the only protocol associated with severe lesions due to high radiant exposure over a confined area. Logistic regression showed no significant effect for EDC, whereas ML-3s significantly increased lesion probability. SIGNIFICANCE: Ultrafast laser protocols produced ΔT comparable to LED but increased the risk of severe gingival lesions. Damage was more closely associated with radiant exposure than with exposure time or average temperature increase. CLINICAL RELEVANCE: Ultrafast laser-based protocols produced gingival temperature increases comparable to those observed with conventional LED curing. Localized energy delivery appears to play a critical role in thermal injury, highlighting the importance of considering radiant exposure and beam characteristics when using high-power light-curing devices near soft tissues.