Effect of Duration of Root Canal Infection on the Ability of Dentin-Pulp Complex Regeneration of Immature Permanent Teeth: An Animal Study

Persistent infection is always considered the most important reason for the failure of dentin-pulp complex regeneration. The present study aimed to evaluate the effect of the duration of root canal infection (from 1-12 weeks) on the ability of dentin-pulp complex regeneration.In this animal study, 64 roots of immature premolar teeth of 4 dogs were randomly divided into the following groups: the positive control group, 8 root canals treated with the regenerative endodontic procedure (REP); the negative control group, 12 infected root canals; the intervention groups, 36 root canals infected with supragingival plaque (1, 3, 6, and 12 weeks) and treated with REP; and an additional positive control group, 8 normal roots. After 3 months, the teeth were investigated by radiographic images and immunohistochemical staining (CD31, CD34, and S100 markers). In addition, DSPP gene expression was assessed using a real-time polymerase chain reaction technique.Based on radiologic evaluation among the intervention groups, the highest root canal development (length and width) occurred in the intervention group of 1 week, and the lowest radiologic results were in the intervention groups of 6 and 12 weeks (1-way analysis of variance, P-value < .05). There was a significant difference between the groups in terms of CD31, CD34, S100, and DSPP expression percentage (1-way analysis of variance, P-value < .05); the highest and lowest expression percentages belonged to the 1- and 12-week groups, respectively, among the intervention groups.This study demonstrated that long root canal infection decreased the ability of the body to regenerate the dentin-pulp complex.