Evaluation of the effect of radiotherapy on dentinal tubule penetration of different root canal seals: A confocal microscope study

Head and neck cancers represent a significant global health concern, with treatment modalities including surgery, radiotherapy, and chemotherapy. Although radiotherapy is a widely utilized therapeutic approach, particularly in advanced-stage cases, it induces various structural alterations in the biomechanics of oral tissues and dental hard tissues. As a consequence of these alterations, salivary flow reduction and radiation-induced caries may occur, necessitating endodontic intervention. The success of root canal treatment relies on the thorough disinfection achieved through an effective irrigation protocol, followed by the hermetic sealing of the root canal system with an appropriate filling material. The penetration of root canal sealers into dentinal tubules is considered a crucial parameter in assessing the quality of the obturation. The efficacy of this penetration is directly influenced by the irrigants used and the physical properties of the selected root canal sealer. Therefore, the selection of irrigating solutions and sealers in endodontic treatment should consider their impact on dentinal tubule penetration. This study aims to evaluate the effects of different chelating agents on the dentinal tubule penetration of root canal sealers in teeth subjected to radiotherapy. A total of 48 extracted human teeth were utilized in the study and randomly divided into two groups. One group underwent radiotherapy for six weeks, receiving a daily dose of 2 Gy, five days per week. In the control group, saline was used as the irrigant, while the experimental groups received EDTA, chitosan, or etidronic acid (HEBP). AH Plus was selected as the root canal sealer in the control group, whereas AH Plus Bioceramic was used in the experimental group. The sealers were mixed with Rhodamine B to facilitate visualization under a confocal laser scanning microscope (CLSM). Following root canal obturation, the samples were sectioned at 3 mm and 7 mm from the apex using a Minitom precision cutting device to obtain 1 mm thick slices. Statistical analyses were performed using IBM SPSS Statistics 22, and comparisons of penetration depth, area, and percentage were conducted using four-way ANOVA with post hoc Tukey HSD tests. The findings of this study indicated that radiotherapy did not produce a statistically significant difference in the dentinal tubule penetration of root canal sealers; however, the penetration values were mathematically lower in irradiated teeth. Additionally, no significant differences were observed in the penetration of root canal sealers among the different chelating agents and sealer types. Key Words: Penetration, Laser scanning confocal microscope, EDTA, Chitosan, Etidronic Acid, AH Plus, AH Plus Bioceramics, Radiotherapy