A Study On The Apical Sealing Ability Of Retrograde Root Canal Treatment

Studies indicate that an infected necrotic pulp and periapical inflammation is found in approximately10%of prosthodontic abutment teeth, then RCT is indicated. However, endodontic access cavity preparation in abutment teeth through the crown might provoke a series of complications, such as root perforation and loosening of the crown. Removal of the crown will increase the patient’s unnecessary spending. How can we not only heal the periapical lesion, and at the same time to leave the crown intact. Jonasson et al. describes a retrograde root canal treatment, take the "periapical surgery" approach, with retrograde approach to shape, clean and fill the canal which leaves the crown intact. However, this technology is limited to case reports, no systematic theoretical basis for its viability.In this study, using dye leakage to evaluate the apical microleakage of root-end retrofilling and retrograde root canal treatment, providing the theoretical basis for clinical application of retrograde root canal treatmentObjective In this study, using dye leakage to evaluate the apical microleakage of three different retrofilling techniques (conventional root canal treatment followed by root-end retrofilling, retrograde root canal treatment and root-end retrofilling), providing the theoretical basis for clinical treatment.Methods This study used60human anterior teeth and premolar teeth. The teeth were collected in Department of maxillofacial surgery of Anhui Medical University Affiliated Stomatological Hospital from September2011to July2012. All teeth were extracted for periodontal or orthodontic reasons.Experiment1:Thirty teeth were randomly separated in3experimental groups of10teeth each. All the specimens were instrumented and filled with three different techniques(conventional root canal treatment followed by root-end retrofilling, retrograde root canal treatment and root-end retrofilling). The teeth were suspended in a glass recipient through a steel wire device fixed on the coronal region, allowing the immersion of the3mm short of apical portion in a1%rhodamine B aqueous solution for48h. After that, the samples were submitted to longitudinal wear until half of the root remained. The specimens were observed under a stereomicroscope, then the largest linear dye penetration between the retrofilling material and tooth structure was measured.Experiment2:Thirty teeth were randomly separated in3experimental groups of10teeth each. All the specimens were instrumented and filled with three different techniques as Experiment1. The teeth were suspended in a glass recipient through a steel wire device fixed on the coronal region, and1%rhodamine B aqueous solution was placed in root canal through the access cavities with syringe. After7day, the samples were submitted to longitudinal wear until half of the root remained. The specimens were observed under a stereomicroscope, then the length of filling material has not been penetrated was measured at material/tooth interface.PASW Statistics18.0statisticalsoftware was used to analyze the data by one-way ANOVA and Tukey’s test. Statistically significant differences among the groups were set at p<0.05.Results Experiment1:The samples retrofilled with three different techniques all have different levels of dye leakage. The lowest dye penetration means was observed in group1(1.12±0.81mm), group2had the highest microleakage (1.94±2.03mm). For comparison between pairs of groups, the Tukey’s test was applied and showed there were no statistically significant differences between groups1,2,groups2,3and groups1,3(P>0.05). Statistical analysis by one-way analysis of variance show there were no statistically significant differences between groups (P>0.05).Experiment2:For comparison between pairs of groups, the Tukey’s test was applied and showed there were no statistically significant differences between groups1,2(P>0.05). The length of filling material has not been penetrated of group1and group2was significantly higher than group3(P≤0.05). Statistical analysis by one-way analysis of variance show there were no statistically significant differences between group1and group2(P>0.05), and the length of filling material has not been penetrated of group1and group2was significantly higher than group3(P<0.05).Conclusion:The results of this in vitro study showed that retrograde root canal treatment and root-end retrofilling can effectively closed root-end in some cases, prevented apical microleakage. Some of teeth especially prosthodontic abutment teeth are not suitable for conventional endodontic treatment, this technology can be used. Within the limitations of this laboratory study, all three retrofilling techniques (conventional root canal treatment followed by root-end retrofilling, retrograde root canal treatment and root-end retrofilling) displayed microleakage, it suggested that outcome of periapical surgery are uncertainly. additional studies on materials, techniques and methods are still to be performed.