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

•Accurate gingival temperature rise was measured in swine gingiva.•Exposure to polywave LED light caused significant gingival temperature rise.•Higher exposure values increase the probability of gingival lesion.•Rubber dam cannot protect gingiva when higher radiant exposure values are delivered.•The presence of rubber dam may increase the probability of gingival lesion.

ObjectiveThis 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).MethodsAfter 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.ResultsWithout 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.SignificanceExposure to a LCU light might be harmful to swine gingiva only when high radiant exposure values are delivered, regardless of the use of RD.