Thermal micro-insults during routine dental procedures: a forgotten determinant of pulp and dentine fate - a scoping...

Thermal changes generated during routine dental procedures have traditionally been evaluated only in relation to acute pulpal injury and irreversible temperature thresholds. A growing body of experimental evidence suggests that repeated low-grade heat exposure may produce cumulative sub-clinical biological changes within the dentine-pulp complex, a phenomenon we here group under the working term "thermal micro-insults" (TMI).

To map the available literature on sub-threshold, sub-lethal and sub-ablative thermal exposure of the dentine-pulp complex during routine restorative and endodontic procedures, and to identify concepts, mechanisms, evidence gaps and clinically relevant thermal parameters.

A scoping review was conducted following the Joanna Briggs Institute (JBI) methodology and reported according to the PRISMA Extension for Scoping Reviews (PRISMA-ScR). PubMed/MEDLINE, Scopus, Web of Science and the Cochrane Central Register of Controlled Trials were searched from January 1965 to May 2026 using combined keywords covering thermal injury, intrapulpal temperature, dentine-pulp complex, heat-shock response and the specific dental procedures under consideration. In vitro, ex vivo, in vivo animal and human studies, and prior narrative or systematic reviews were eligible. Two reviewers independently screened records; disagreements were resolved by discussion.

Heat generated during cavity preparation, finishing/polishing, photopolymerisation, ultrasonic instrumentation and laser use can transiently raise intrapulpal temperature. Even when the classical 5.5 °C Zach and Cohen threshold is not exceeded, repeated sub-threshold exposures have been associated in in vitro and animal studies with heat-shock-protein expression (HSP25, HSP27, HSP70), altered mitochondrial function and reactive-oxygen-species generation, up-regulation of pro-inflammatory cytokines (IL-1β, IL-6, IL-8, TNF-α), activation of thermosensitive TRPV1/TRPA1 channels, and long-term changes such as reparative dentine deposition, focal fibrosis and calcification. Current evidence is dominated by in vitro work using extracted teeth without pulpal microcirculation; clinical validation and standardised sub-threshold thermal-dose descriptors are lacking.

TMI should be viewed as a plausible but still developing hypothesis rather than an established clinical entity. Recognising cumulative low-grade heat exposure as a potentially modifiable biological factor may complement existing minimally invasive restorative and endodontic principles, guide the design of low-heat instrumentation and cooling strategies, and inform future in vivo research.