Dentine sensitivity caused by illumination of intraoral scanner and light curing unit

Patients often compliant sensitivity to high-intensity light irradiated application during dental procedures. This study aims to investigate tooth sensitivity caused by high-intensity light irradiated from an intraoral scanner (IOS) and a light-curing unit (LCU).

Forty-five teeth from 45 healthy volunteers were included. These were equally classified into three groups using the cold test (4 ± 1 °C) and NRS pain assessment; A=control, B=cavity without sensitivity, and C=cavity with sensitivity. Two thermocouple probes were attached to the cervical area of the experimental and control tooth with a composite resin. Tooth sensitivity response by participant grip force was monitored. The digital oscilloscope was used to record two surface temperatures and a pain response during an IOS or a LCU irradiation. The high-intensity light from a LCU and an IOS was randomly applied at 2 mm above the cervical area for 20s. The data were compared statistical with two-way repeated measures ANOVA and Pearson's correlation.

The illumination caused increasing surface temperatures of about 22.98 ± 3.20 °C for a LCU and 5.86 ± 1.46 °C for an IOS from a 29.5 °C baseline. As the light intensity from the LCU generated more heat, participants reported more tooth sensitivity with a shorter response time (2.10s to 18.70s). There was a positive correlation between surface temperature and pain response (R2 = 0.232; p<0.01).

The heat from high-intensity light from a LCU and an IOS can cause tooth sensitivity in some individuals especially those who had a cervical cavity with dentine sensitivity. The higher light intensity would raise the surface temperature and cause a higher sensitivity response. Key words:Light curing unit, intraoral scanner, tooth temperature, dentine sensitivity.