Introduction Heat is generated and transferred to the dentine-pulp complex during various dental procedures, such as from friction during cavity preparations, exothermic reactions during the polymerisation of restorative materials and when polishing restorations. For in vitro studies, detrimental effects are possible when intra-pulpal temperature increases by more than 5.5°C (that is, the intra-pulpal temperature exceeds 42.4°C). This excessive heat transfer results in inflammation and necrosis of the pulp. Despite numerous studies stating the importance of heat transfer and control during dental procedures, there are limited studies that have quantified the significance. Past studies incorporated an experimental setup where a thermocouple is placed inside the pulp of an extracted human tooth and connected to an electronic digital thermometer. Methods This review identified the opportunity for future research and develop both the understanding of various influencing factors on heat generation and the different sensor systems to measure the intrapulpal temperature. Conclusion Various steps of dental restorative procedures have the potential to generate considerable amounts of heat which can permanently damage the pulp, leading to pulp necrosis, discoloration of the tooth and eventually tooth loss. Thus, measures should be undertaken to limit pulp irritation and injury during procedures. This review highlighted the gap for future research and a need for an experimental setup which can simulate pulp blood flow, temperature, intraoral temperature and intraoral humidity to accurately simulate the intraoral conditions and record temperature changes during various dental procedures.

AimTo record the pulp temperature at different tooth sites during fabrication of two different temporary crown systems.MethodologyTwo temporary crown systems were investigated; a conventional direct fabricated and a preformed thermoplastic resin system. Extracted caries-free human teeth (incisor, premolar and molar) were prepared for full coverage ceramic restoration with roots sectioned below the cemento-enamel junction. Thermocouple wires were secured at the surface of crown material, the cut dentine and inside the pulp cavity. Provisional crowns (n = 10/group) from each system were formed prior to placement in a water bath of 37 °C to simulate pulpal temperature. Temperatures were recorded using a K-type thermocouple data logger to collect the mean and peak temperature during crown fabrication. Statistical analysis was carried out on all tested groups and heat flow was calculated.ResultsFor direct fabricated crowns, the mean rise in pulpal temperature recorded was 0.1 °C with the mean temperature range of 37.3 °C–37.8 °C. For the preformed thermoplastic crowns, the mean rise in pulpal temperature recorded was 37.3 °C–45.1 °C. The increase in temperature was significantly higher (6.5 °C for the incisor group, 7.5 °C for the premolar group, and 6.7 °C for the molar group). For both crown systems, the temperature difference between the three different sites; pulp, crown and tooth surface showed a statistical difference (P < 0.01).ConclusionsThe direct fabrication system showed minimal temperature changes within the teeth, while the preformed thermoplastic fabrication system showed larger temperature change in the teeth.

Background and objectives: There has been a lack of studies regarding the marginal seal and structural durability of a novel temporary crown system (Hi-tempo) manufactured from a polylactic (PLA) based resin thermoplastic material especially in terms of cyclic loading. Therefore, the purpose of this pilot study was to investigate the efficiency of this novel temporary crown system’s (Hi-tempo) marginal seal and structural durability in terms of cyclic loading. Methods: A crown preparation was duplicated in bovine teeth (n =15) using a copy mill machine. The specimens were divided into three groups and temporary crowns were fabricated that consisted of: control group, Luxatemp (bis-acrylic), Hi-tempo crown, PLA based and Hi-tempo window type crown, PLA based with resin cusps. Marginal dimensional change was measured before and after cyclic loading with a 93.36 N force, 0.63 HZ, for 45360 cycles (stimulating 21 days in vivo) in water pigmented with a red dye. The marginal change was statistically analysed and the surface roughness was analysed using scanning electron microscopy (SEM). Results: Statistical significance (p<0.05) was found in the marginal changes of the control versus the Hitempo window and the Hi-tempo groups. SEM analysis revealed that the control crowns, had a much rougher surface with micro-cracks compared to PLA based crowns which had homogenous surfaces. All the specimens showed leakage of the red dye into the internal fitting surfaces of the crowns. Conclusions: The novel system showed promising and comparable results in terms of structural durability and marginal seal compared to the conventional system.