Comparison of in vivo and in vitro models to evaluate pulp temperature rise during exposure to a Polywave® LED light curing unit

Abstract

Objectives: To measure and compare in vivo and in vitro pulp temperature (PT) increase (ΔTEMP) over baseline, physiologic temperature using the same intact upper premolars exposed to the same Polywave ® LED curing light. Methodology: After local Ethics Committee approval (#255,945), local anesthesia, rubber dam isolation, small occlusal preparations/minute pulp exposure (n=15) were performed in teeth requiring extraction for orthodontic reasons. A sterile probe of a temperature measurement system (Temperature Data Acquisition, Physitemp) was placed within the pulp chamber and the buccal surface was sequentially exposed to a LED LCU (Bluephase 20i, Ivoclar Vivadent) using the following exposure modes: 10-s low or high, 5-s Turbo, and 60-s high. Afterwards, the teeth were extracted and K-type thermocouples were placed within the pulp chamber through the original access. The teeth were attached to an assembly simulating the in vivo environment, being similarly exposed while real-time temperature (°C) was recorded. ΔTEMP values and time for temperature to reach maximum (ΔTIME) were subjected to two-way ANOVA and Bonferroni's post-hoc tests (pre-set alpha 0.05). Results: Higher ΔTEMP was observed in vitro than in vivo . No significant difference in ΔTIME was observed between test conditions. A significant, positive relationship was observed between radiant exposure and ΔTEMP for both conditions ( in vivo : r2=0.917; p<0.001; in vitro : r2=0.919; p<0.001). Conclusion: Although the in vitro model overestimated in vivo PT increase, in vitro PT rise was close to in vivo values for clinically relevant exposure modes.

<p>Heat Development in the Pulp Chamber During Curing Process of Resin-Based Composite Using Multi-Wave LED Light Curing Unit</p>

“…25,26 Furthermore, a recent study comparing in vitro and in vivo models to investigate temperature increase when exposed to LED LCU concluded that at clinically relevant curing times only a small difference in temperature was observed. 27 Another methodological consideration in this study was the accurate placement of the thermocouple in the pulp chamber. In part 3, we aimed to position the thermocouple close to the pulpal ceiling and the cavity floor.…”

Light-curing units used in dentistry: Effect of their characteristics on temperature development in teeth

“…Our experimental setup can therefore be considered as a worst case clinical situation, taking additionally into consideration the small thickness of remaining dentin. A study comparing in vitro and in vivo models to investigate temperature increase when exposed to LED-LCUs concluded that at a clinical relevant CT (such as 20 s in our study) only small differences of temperature development were observed between the two models 32) . In addition, in vitro model can be considered advantageous over in vivo model for ethical reasons.…”

The effect of current pulp capping materials against intrapulpal temperature increase in primary teeth. An in-vitro study by pulpal microcirculation simulation model

“…Nevertheless, a current study evaluated how similar an in vitro model is able to reproduce temperature increase values compared to the in vivo model, in anesthetized intact, unrestored, human upper premolars, in order to validate the in vitro methodology. 27 Runnacles et al. (2019) reported that, in vitro pulpal temperature increase values were close to in vivo values when clinically relevant exposure modes were delivered.…”

“…(2019) reported that, in vitro pulpal temperature increase values were close to in vivo values when clinically relevant exposure modes were delivered. 27 Since the ethical problems in front of such in-vivo studies and the findings of Runnacles et al., in-vitro studies that evaluate the temperature increase in pulp chamber are still valid. In our knowledge, it is the first study about intrapulpal temperature increases during light-curing of compomer restorations in primary teeth and the protective effects of current pulp capping materials against these temperature increases.…”