Objectives: To evaluate the effects of an LED light curing unit (LCU) on human, in vivo, coronal pulp temperature (PT).
Methods: An approved research protocol was used: #255,945, Ponta Grossa State University. After rubber dam isolation and local anesthesia, small occlusal preparations were made in upper first premolars (n=15) that required extraction for orthodontic reasons, resulting in minute pulp exposures. The sterile probe of a temperature acquisition system (Temperature Data Acquisition, Physitemp) was inserted directly into the coronal pulp. After a stable temperature was reached, the buccal surfaces were sequentially exposed to light from a polywave LED LCU (Bluephase 20i, Ivoclar Vivadent): 10-s in low intensity (10-s/L); 10-s in high intensity (10-s/H); 5-s in Turbo intensity (5-s/T); and 60-s in high intensity (60-s/H), allowing a 7-min span between each exposure to return to baseline. Real-time PT (°C) was continuously monitored at 0.2-s intervals. Peak PT and PT increase from baseline (ΔT) after exposure were subjected to 1-Way, repeated measures ANOVAs, followed by Bonferroni's post-hoc test (pre-set alpha = 5%).
Results: The following table present study findings: mean ± 1 sd. Most curing modes increased pulp temperature significantly (p<0.05) in comparison to baseline temperature (35.3±0.7˚C). Only the 10-s/L resulted in no significant increase in temperature (p=0.641).
Curing Mode
| Max Pulp Temp (˚C)
| ΔT Above Baseline (˚C)
|
10-s/L
| 35.8 ± 0.7 C
| 0.5 ± 0.2 C
|
10-s/H
| 36.3 ± 0.7 B
| 1.0 ± 0.3 B
|
5-s/T
| 36.2 ± 0.7.B
| 1.0 ± 0.3 B
|
60-s/H
| 40.1 ± 1.2. A
| 4.8 ± 1.0 A
|
Within a column, cell values with similar upper case letters are not significantly different
Conclusions: The LED curing light increased in vivo pulp temperature in comparison to the baseline pulp temperature. Extended exposure periods and higher light output resulted in elevated pulpal temperature. However, no intrapulpal temperature approached the 5.5˚C increase thought to be associated with irreversible tissue damage.