Pulpal response to prolonged dentinal exposure to sodium hypochlorite.
OBJECTIVE
The aim of this study was to examine the effect of undiluted NaOCl on vital pulp tissue when applied to freshly cut dentine.


METHODS
Class V cavities were prepared to a depth of 2 mm in 20 teeth in four Beagle dogs. The cavities on one side of each dog were irrigated continuously for 5 min with 5.25% NaOCl, whilst the cavities on the opposite side in each dog were irrigated with saline for the same length of time. Prior to filling each cavity with Cavit, they were again rinsed with saline and gently dried with an air stream. The dogs were sacrificed to allow for investigation of pulpal conditions under the cavities after periods of 24 h, 1 week, and 4 weeks. Histological preparations were made and stained with H & E for evaluation of the pulp subjacent to each cavity. The tissues were examined for presence of inflammatory cells and categorized as (i) no inflammation, (ii) mild, (iii) moderate, and (iv) severe inflammation.


RESULTS
The six teeth in the 24 h observation group all showed mild inflammation, both in the NaOCl and the saline groups. After 1 week and 4 weeks, the pulps from all the teeth were free of inflammatory cells.


CONCLUSIONS
Under the conditions of this experiment, the use of NaOCl in a freshly cut cavity in an intact tooth of a dog, with exposed dentinal tubules, does not appear to cause additional pulpal damage to that caused by the physical contact in cutting tooth structure.
Tang
H M
HM
Department of Endodontics, School of Dentistry, Loma Linda University, Loma Linda, California, USA.
Nordbö
H
H
Bakland
L K
LK
D000818:Animals; D002133:Calcium Sulfate; D004396:Coloring Agents; D003737:Dental Cavity Preparation / Q000145:classification; D003738:Dental Cements; D003782:Dental Pulp / Q000187:drug effects*; D003793:Dental Restoration, Permanent; D003804:Dentin / Q000187:drug effects*; D004202:Disinfectants / Q000494:pharmacology*; D004285:Dogs; D004338:Drug Combinations; D005456:Fluorescent Dyes; D005500:Follow-Up Studies; D009504:Neutrophils / Q000473:pathology; D009804:Odontoblasts / Q000473:pathology; D011145:Polyvinyls; D011671:Pulpitis / Q000145:classification / Q000473:pathology; D012973:Sodium Hypochlorite / Q000494:pharmacology*; D013997:Time Factors; D015034:Zinc Oxide
D004396:Coloring Agents; D003738:Dental Cements; D004202:Disinfectants; D004338:Drug Combinations; D005456:Fluorescent Dyes; D011145:Polyvinyls; C020872:Cavit; D012973:Sodium Hypochlorite; D015034:Zinc Oxide; D002133:Calcium Sulfate