The influence of endodontic access cavity design on the efficacy of canal instrumentation, microbial reduction, root canal filling and fracture resistance in mandibular molars

Abstract

Aim To assess the impact of conservative endodontic access cavities (CEC) and truss access cavities (TAC) during root canal treatment performed on mandibular molars in terms of: ability to shape and fill root canals, microbial reduction in canals, and cleaning of the pulp chamber. In addition, the fracture resistance of the teeth after coronal restoration was assessed. Traditional endodontic cavities (TEC) were used as a reference technique for comparison. Methodology Thirty extracted intact mandibular molars were scanned in a microcomputed tomography device (micro‐CT), matched based on similar anatomical features and assigned to TEC, CEC or TAC groups (n = 10). The specimens were accessed accordingly, and root canals were contaminated with bacterial suspensions of Enterococcus faecalis (21 days). Subsequently, the first microbial sample was collected from root canals (S1). The canals were initially prepared with Reciproc Blue R25 instrument followed by a second instrumentation using Reciproc Blue R40. Eight mL of 0.5% NaOCl were used as an irrigant for each instrument. A final irrigation protocol was performed with 2 mL of 0.5% NaOCl, 2 mL of 17% EDTA and another 2 mL of 0.5% NaOCl. Microbial samples were collected from root canals after R25 (S2), R40 (S3) and final irrigation (S4). The teeth were rescanned after S4. Then, root canals were filled, rescanned, restored and the teeth subjected to fracture resistance tests. The statistical analysis was performed with type I negative binomial and beta 0‐1 inflation regression models for microbiological analysis. Instrumentation, filling and resistance to fracture results were subjected to anova and Tukey tests (P < 0.05). Results S4 revealed no significant variations in microbial reduction amongst the groups (P > 0.05). TEC had a significantly lower percentage of unprepared surface area than CEC (P < 0.05). No differences were found regarding the percentage of dentine removed, transportation, centring ability and filling voids amongst the groups (P > 0.05). The TEC group had a significantly lower volume of remaining root filling material within the pulp chamber than CEC and TAC groups (P < 0.05). There was no difference regarding fracture resistance amongst the groups (P > 0.05). Conclusion Conservative access cavities did not offer any advantage in comparison with the traditional endodontic cavities in any of the parameters considered. Furthermore, conservative methods were associated with larger percentages of unprepared canal surface area and larger volumes of remaining root filling material within the pulp chamber.

Impact of Access Cavity Design on Fracture Resistance of Endodontically Treated Molars: A Systematic Review

“… 31 Lastly, Barbosa et al in 2020 got similar results to Maske et al when he compared TradAC to ConsAC on forty mandibular molars. 32 …”

“… - The initial hypothesis of the study was rejected since the performance of a minimally invasive endodontic access did not considerably improve the fracture strength of the dental crown when compared to conventional access. Barbosa et al 32 2020 Rio de Janeiro, Brazil. n = 40 Controlled group (n=10) TEC (n=10) CEC (n=10) Truss (TAC) (n=10) TEC (748 ± 238 N) CEC (971 ± 377 N) TAC (1033 ± 414 N) No significant difference in fracture resistance among the groups (P<0.05).…”

“…A recent study by Barbosa et al in 2020 evaluated the quality of root canal disinfection following the ConsAC procedure and obtained larger percentages of unprepared canal surface area and a larger volume of remaining root filling material within the pulp chamber. 32 …”

“…11,14,21 A recent study by Barbosa et al in 2020 evaluated the quality of root canal disinfection following the ConsAC procedure and obtained larger percentages of unprepared canal surface area and a larger volume of remaining root filling material within the pulp chamber. 32 Clinically, the ConsAC procedure faces clinicians with many challenges. The main challenge in molar teeth is the accessibility to the offending tooth.…”

“…Maske et al in 2020 found that there was a significant difference between healthy intact teeth compared with the other groups, but no difference between TradAC and ConsAC groups in fifty lower third molars 31. Lastly, Barbosa et al in 2020 got similar results to Maske et al when he compared TradAC to ConsAC on forty mandibular molars 32.…”