Pulpal temperature increases with Er:YAG laser and high-speed handpieces.
BACKGROUND
During tooth preparation, both high-speed handpieces and lasers generate heat, which, if not controlled, can cause pulpal necrosis.


OBJECTIVE
The aim of this study was to compare temperature increases produced by a high-speed dental handpiece with those produced by a relatively new instrument, the Er:YAG (erbium: yttrium-aluminum-garnet) laser.


METHODS
Thirty bovine mandibular incisors were reduced to an enamel/dentin thickness of 2.5 mm. Class V preparations were completed to a depth of 2.0 mm, measured with a caliper or by a mark on the burs. A thermocouple was placed inside the pulp chamber to determine temperature increases (degrees C). Analysis was performed on the following groups (n=10): Group I, high-speed handpiece without water cooling, Group II, high-speed handpiece with water cooling (30 mL/min), and Group III, the noncontact Er:YAG laser (2.94 microm at 350 mJ/10 Hz) with water cooling (4.5 mL/min). The temperature increases were recorded by a computer linked to the thermocouples. The data were analyzed using the Kruskal-Wallis test. The Dunn multiple comparison test was used as post hoc test (alpha=.05).


RESULTS
The average temperature rises were: 11.64 degrees C (+/- 4.35) for Group I, 0.96 degrees C (+/- 0.71) for Group II, and 2.69 degrees C (+/- 1.12) for Group III. There were no statistical differences between Groups II and III; both II and III differed from Group I significantly (P=.000 and P=.002, respectively).


CONCLUSIONS
The preparations made with the high-speed and the laser instrument generated similar heat increases under water cooling. Water cooling was essential to avoid destructive temperature increases when using both the high-speed handpiece and laser.
School of Dentistry, São Paulo State University (UNESP), Brazil. bncavalcanti@uol.com.br
Bruno Neves
BN
Cavalcanti
José Luiz
JL
Lage-Marques
Sigmar Mello
SM
Rode
D000538:Aluminum Silicates; D000818:Animals; D001831:Body Temperature / Q000502:physiology*; D002417:Cattle; D003737:Dental Cavity Preparation / Q000145:classification / Q000295:instrumentation*; D003754:Dental High-Speed Equipment; D003782:Dental Pulp / Q000503:physiopathology*; D003786:Dental Pulp Cavity / Q000503:physiopathology; D004871:Erbium; D006358:Hot Temperature; D053685:Laser Therapy; D012815:Signal Processing, Computer-Assisted; D018709:Statistics, Nonparametric; D013821:Thermometers; D014867:Water; D015019:Yttrium
D000538:Aluminum Silicates; D014867:Water; D015019:Yttrium; D004871:Erbium