Analysis of temperature rise and the use of coolants in the dissipation of ultrasonic heat buildup during post removal.

By Davis S, Gluskin AH, Livingood PM, Chambers DW

Date: 05/2011
Journal: JOE

Summary: 

Purpose:  to calculate probabilities for tissue injury and to measure effective- ness of various coolant strategies in countering heat buildup produced by dry ultrasonic vibration during post removal.

N= 10 single canal (premolars or canines).

Materials & Methods:

  • All teeth were standardized; access, C/S, and obturation.
  • Post spaces were prepared 10 mm in depth with #5 ParaPost drill. Posts cemented with Panavia 21. adhesive resin cement .
  • Two K-type Chromega-Alomega thermocouples attached to tooth and post. Data set consisted of cervical and apical measures of temperature increase at 1-second intervals from baseline during continuous ultrasonic instrumentation until a 10oC increase in temperature at the cervical site was registered and the teeth were allowed to cool under the assistance of 5 cooling methods. : (1) air only from 3-way syringe; (2) water spray from 3-way syringe; (3) small cotton pellet #3 sprayed for 2 seconds with Endo-Ice and applied; (4) large cotton pellet #0 sprayed for 2 seconds with  Endo-Ice applied to the post; (5) cooling by ambient air.

Most highlighted Results: 

1.Injurious temperatures are easily reached in less than 1 minute during dry ultrasonic instrumentation of metallic posts.

2.Endo-Ice applied with large cotton pellet was the most efficient coolant method, but this was not statistically significant over less costly options. 3.The 4 active coolants used in this study were all effective in reducing the probability of temperature damage caused by instrumentation.

Clinical significance: Cycles of short instrumentation times with active coolants are effective in reducing the probability of tissue damage when teeth are instrumented dry.