Influence of Delayed Material Placement on In Vivo Intrapulpal Temperature Rise in Class V Resin Composite Restorations.

Objective: This study evaluated the effect of delay of the etch-and-rinse bonding procedure on in vivo real-time intrapulpal temperature during restoration of Class V preparations on human premolars.

Methods and materials: Intact premolars planned for orthodontic extraction from 11 volunteers received infiltrative anesthesia and were isolated using a dental dam. An occlusal preparation was performed using a high-speed diamond bur with air-water spray until obtaining minimal pulp exposure, followed by insertion of a sterile thermocouple probe. A buccal Class V preparation was made using a high-speed diamond bur cooled using air-water spray. To simulate the time spent on caries removal, material placement was delayed 15 minutes until physiologic pulpal temperature (PT) was reestablished (approximately 35°C). Preparations were acid etched and rinsed. A two-step etch-and-rinse bonding agent, Single Bond Universal (Solventum, St. Paul, MN, USA) or Tetric Nano Bond (Ivoclar Vivadent, Schaan, Lichtenstein), was applied and photocured following manufacturers' instructions. The teeth were restored using conventional (Filtek Z250 or Filtek Z350, Solventum) or bulk-fill (Tetric N Ceram Bulk-fill, Ivoclar Vivadent) resin composites, which were photocured with a dual-peak LED light-curing unit (Bluephase 20i, Ivoclar Vivadent). Peak PT and ΔT values were analyzed using two-way repeated measures ANOVA and Bonferroni post hoc tests.

Results: Etch-and-rinse and solvent evaporation procedures reduced PT, despite restoration starting at physiologic PT. Only the 40-second exposure of Filtek Z350 resulted in significantly higher peak PT values compared to baseline (38.2°C ± 2.4°C). ΔT values for Z250 were not significantly different from those for Tetric N-Ceram Bulk-fill.

Conclusion: Even when etch-and-rinse bonding procedures started at physiologic PT, PT decreased, preventing harmful levels of temperature rise in the pulp.