Analysis of temperature increase in swine gingiva after exposure to a Polywave ® LED light curing unit

Objective This study evaluated the temperature increase in swine gingival temperature after exposure to light emitted by a Polywave® LED light curing unit (LCU, Bluephase 20i, Ivoclar Vivadent). Methods After local Ethics Committee approval (protocol 711/2015), 40 pigs were subjected to general anesthesia and the LCU tip was placed 5 mm from the buccal gingival tissue (GT) close to lower lateral incisors. A thermocouple probe (Thermes WFI, Physitemp) was inserted into the gingival sulcus before and immediately after exposure to light. Real-time temperature (°C) was measured after the following exposure modes were applied: High Power (20s-H, 40s-H, and 60s-H) or Turbo mode (5s-T), either with or without the presence of rubber dam (RD) interposed between the LCU tip and GT (n = 10). The presence of gingival lesions after the exposures was also evaluated. Peak temperature (°C) and the temperature increase during exposure over that of the pre-exposure baseline value (ΔT) data were analyzed using 2-way ANOVA followed by Bonferroni’s post-hoc test (α = 5%). A binary logistic regression analysis determined the risk of gingival lesion development. Results Without RD, no significant difference in ΔT was observed among 20s-H, 40s-H, and 60s-H groups, which showed the highest temperature values, while the 5s-T exposure showed the lowest ΔT, regardless of RD. RD reduced ΔT only for the 20s-H group (p = 0.004). Gingival lesions were predominantly observed using 40s-H, with RD, and 60s-H, with and without RD. Significance Exposure to a LCU light might be harmful to swine gingiva only when high radiant exposure values are delivered, regardless of the use of RD.