Influence of Class V preparation on in vivo temperature rise in anesthetized human pulp during exposure to a Polywave^® LED light curing unit

Objective: This in vivo study evaluated pulp temperature (PT) rise in human premolars having deep Class V preparations during exposure to a light curing unit (LCU) using selected exposure modes (EMs). Methods: After local Ethics Committee approval, intact first premolars (n = 8) requiring extraction for orthodontic reasons, from 8 volunteers, received infiltrative and intraligamental anesthesia and were isolated using rubber dam. A minute pulp exposure was attained and sterile probe from a wireless, NIST-traceable, temperature acquisition system was inserted into the coronal pulp chamber to continuously monitor PT (°C). A deep buccal Class V preparation was prepared using a high speed diamond bur under air-water spray cooling. The surface was exposed to a Polywave^® LED LCU (Bluephase 20i, Ivoclar Vivadent) using selected EMs, allowing 7-min span between each exposure: 10-s in low (10-s/L), 10-s (10-s/H), 30-s (30-s/H), or 60-s (60-s/H) in high mode; and 5-s-Turbo (5-s/T). Peak PT values and PT increases over physiologic baseline levels (ΔT) were subjected to 1-way, repeated measures ANOVAs, and Bonferroni's post-hoc tests (α = 0.05). Linear regression analysis was performed to establish the relationship between applied radiant exposure and ΔT. Results: All EMs produced higher peak PT than the baseline temperature (p < 0.001). Only 60-s/H mode generated an average ΔT of 5.5 °C (p < 0.001). A significant, positive relationship was noted between applied radiant exposure and ΔT (r² = 0.8962; p < 0.001). Significance: In vivo exposure of deep Class V preparation to Polywave^® LED LCU increases PT to values considered safe for the pulp, for most EMs. Only the longest evaluated EM caused higher PT increase than the critical ΔT, thought to be associated with pulpal necrosis.