RESUMEN
OBJECTIVES: The aim of this study was to determine the periapical healing rate and complications arising from non-surgical root canal treatment (NSRCT) conducted through the existing and retained restoration, compared to that conducted after removal of restoration (direct or indirect) with subsequent placement of a new crown. MATERIALS AND METHODS: Two-hundred-and-forty-five teeth met the inclusion criteria and were followed up for 2 years. One-hundred-and-six teeth had NSRCT completed through existing cast restorations, and 57 and 82 had the existing crowns and direct restorations removed (respectively) and received a new crown after NSRCT. Periapical healing was assessed radiographically using strict (complete healing) and loose (complete and incomplete healing) criteria. Multivariable logistic regression models were used to investigate the effect of prior restoration removal on periapical healing following NSRCT, adjusting for potential confounding (p < 0.05). RESULTS: There was no significant (p > 0.05) difference in the periapical healing rates amongst teeth accessed through existing crowns (72%, 90%) versus those where crowns (79%, 93%) or direct restorations (77%, 90%) were removed for NSRCT. The findings were adjusted for the significant influencing factor: size of pre-operative radiolucency (p < 0.05). Of the 109 teeth that were initially accessed through existing crowns, 9 (8%) displayed porcelain fracture or crown de-cementation. CONCLUSION: Performing root canal treatment through an existing full coverage restoration did not compromise periapical healing and was associated with a low incidence of associated complications. CLINICAL RELEVANCE: Crown removal before NSRCT is not mandatory for periapical healing but requires a judicious pre-assessment of current and future marginal and restorative integrity.