Efficacy of sonic and ultrasonic activation for removal of calcium hydroxide from mesial canals of mandibular molars: a microtomographic study.
BACKGROUND
The purpose of this study was to use micro-computed tomography (micro-CT) scanning to evaluate the efficacy of sonic and passive ultrasonic irrigation (PUI) on calcium hydroxide (Ca[OH](2)) removal and to measure the volume and percentage of Ca(OH)(2) remaining in the root canal system.


METHODS
The root canals of 46 extracted human mandibular molar teeth were prepared with rotary instruments and randomly assigned to two experimental groups (n = 40) as well as positive and negative controls (n = 6). In each experimental group, 20 teeth were assigned to each irrigation protocol, sonic or passive ultrasonic irrigation. All experimental teeth and the positive controls were filled with Ca(OH)(2), whereas the negative control teeth did not receive Ca(OH)(2). All teeth were scanned using micro-CT scanning to determine the dressing volume. After 7 days, the Ca(OH)(2) was removed in the experimental groups using rotary instrumentation only, and the teeth were again scanned using micro-CT scanning to calculate volume and percentage of Ca(OH)(2) removed. Positive control teeth were not subjected to rotary instrumentation. Experimental samples were then irrigated using either sonic or passive ultrasonic and the volume of remaining Ca(OH)(2) was calculated using micro-CT.


RESULTS
Remnants of Ca(OH)(2) were found in all experimental groups. No Ca(OH)(2) was found in the negative controls, whereas a mean of 8.7 mm(3) of Ca(OH)(2) was recorded in the positive controls. Rotary plus passive ultrasonic irrigation removed significantly more Ca(OH)(2) (85.7%) than rotary plus sonic irrigation (71.5%) (p < 0.001).


CONCLUSIONS
The combination of rotary instrumentation and passive ultrasonic activation for 3 periods of 20 seconds results in significantly lower amounts of Ca(OH)(2) remnants in the canal compared with sonic irrigation.
Department of Endodontics, University of Washington, Seattle, WA, USA.
Anne
A
Wiseman
Timothy C
TC
Cox
Avina
A
Paranjpe
Natasha M
NM
Flake
Nestor
N
Cohenca
James D
JD
Johnson
D002126:Calcium Hydroxide; D003131:Combined Modality Therapy; D003646:Debridement / Q000295:instrumentation / Q000379:methods; D003762:Dental Instruments; D003786:Dental Pulp Cavity / Q000187:drug effects*; D006801:Humans; D008334:Mandible; D008963:Molar; D012387:Root Canal Filling Materials; D012388:Root Canal Irrigants / Q000008:administration & dosage*; D018915:Root Canal Preparation / Q000295:instrumentation* / Q000379:methods; D016369:Smear Layer; D013499:Surface Properties; D007507:Therapeutic Irrigation / Q000295:instrumentation / Q000379:methods; D014465:Ultrasonics; D055114:X-Ray Microtomography
D012387:Root Canal Filling Materials; D012388:Root Canal Irrigants; D002126:Calcium Hydroxide