Study of root canal filling in dogs by using compound coral paste

Zhimin LEI; Min ZHANG

ABSTRACT

BACKGROUND:

The root canal filling materials available have different degrees of noxious stimulation to periapical tissue and cannot induce growth and regeneration of bone at the periapical region. Moreover, the operation of canal filling is not easily controlled.

OBJECTIVE:

To investigate biocompatibility and osteoconductivity between periapical tissue and compound coral paste after root canal filling.

DESIGN:

Controlled observation.

SETTING:

Department of Stomatology in the Renmin Hospital of Wuhan University.MATERIALS The experiment was carried out in the Key Laboratory for Oral Biomedical Engineering by the State Ministry of Education, School of Stomatology in Wuhan University from September 2002 to January 2006. Eight adult female mongrel dogs, weighed 15 kg, were offered by the Wuhan General Hospital of Guangzhou Military Area Command of Chinese PLA (SYXK-2003-0007). Each dog contained 32 root canals, and totally 256 root canals were utilized in this study.

METHODS:

Experimental animals underwent general anesthesia by the intravenous injection of sodium pentobarbital (30 mg/kg), then tracheal intubation was utilized for the root canal filling, and the canals were randomly distributed into two groups experimental group (n=128) with compound coral paste (coral 40 g and iodoform 8 g, offered by the Key Laboratory for Oral Biomedical Engineering by the State Ministry of Education, School of Stomatology in Wuhan University); control group (n=128) with gutta-percha point+zinc oxide-eugenol sealer. One animal was sacrificed by anesthetic overdose at 2, 4, 12 and 24 weeks after root canal filling, dental film by X-ray and light microscope were used for the examination.MAIN OUTCOME

MEASURES:

①Periapical inflammation Cells were counted in a high power field, and three levels were defined as mild (＜100 cells/mm2), moderate (100-200 cells/mm2) and severe (＞200 cells/mm2).②destruction and regeneration of periapical tissues.③bone substitute of compound coral paste in periapical regions.

RESULTS:

Eight mongrel dogs were all involved in the result analysis.①Periapical shadow by X-ray film Distinct shadow at root apex area can not be observed in the experimental group at each stage. While two cases appeared the root apex shadow in the control group at 12 and 24 weeks, respectively.②Histopathological observation At 2 weeks after root filling,inflammatory cell infiltration was observed in each group, which was dominantly neutrocyte. There was a mild inflammation in experimental group and a moderate inflammation in control group. Four weeks after root filling, there were focal inflammatory cells infiltrated around the coral particles in the experimental group, but in the control group there were a great deal of inflammatory cells in periapical tissue. Twelve weeks after root filling, in experimental group, there was no inflammatory cell infiltration was observed, the deposition of bone combined tightly with coral particles was detected, and apical foramen became smaller;, but in the control group, there were still inflammatory cells circumvohiting the gutta-percha point. After 24 weeks, coral particles was not observed at the root filling region in the experimental group, and they were replaced by a great deal deposition of bones, root foramens were sealed completely and grew into root canal wall. Root apex was coated with fibrous tissue in the control group.

CONCLUSION:

This compound coral paste shows good compatibility after filling, promotes the osteoconductivity, and seals the root foremen, so it can be used as a root canal filling material.