Influence of Endodontic Access Cavity Design on Fracture Strength of Maxillary Incisors and Premolars and on Fatigue Resistance of Reciprocating Instruments

Abstract

The aim of this study was to compare the effect of two different access cavity designs on fracture strength of endodontically treated teeth and on cyclic fatigue resistance of Reciproc blue instruments. Methods: Forty (40) maxillary central incisor teeth and forty (40) upper first premolars were selected and divided into 4 groups (n = 20/group): Group 1A, incisors prepared with conservative access cavity (CEC); group 1B, incisors prepared with traditional access cavity (TEC); group 2A, premolars prepared with CEC; group 2B, premolars prepared with TEC. After access cavity preparation, all teeth were endodontically treated, restored, and then loaded to fracture. A total of 80 Reciproc blue R25 files were used for root canal shaping and then tested for cyclic fatigue. Normality of data distribution was evaluated by Kolmogorov-Smirnov test. Data were statistically analyzed by Independent T-test and the significance level was set at p < 0.05. Results: No statistically significant differences in fracture strength were found between the two tested access cavities both for incisors (P = 0.70) and premolars (0.422). Cyclic fatigue resistance of Reciproc blue R25 was significantly reduced in endodontically treated teeth with CEC (P < 0.001). Conclusions: Within the limits of the present in vitro study, CEC does not increase fracture strength of endodontically treated teeth in comparison to TEC. Conservative Endodontic Cavity causes more cyclic fatigue of Reciproc blue R25 than Traditional Endodontic Cavity.

Present status and future directions – Minimal endodontic access cavities

“…One of the most important methodological aspects of research design is the creation of a reliable baseline inasmuch as anatomical discrepancies of sampling may have a direct impact on the outcome. Although it seems logical that a proper anatomical pairing of teeth allocated for each experimental group may compromise the final conclusions, several studies performed sample selection based only on two‐dimensional radiographs (Corsentino et al, 2018; Krishan et al, 2014; Moore et al, 2016), external measurement of teeth (Corsentino et al, 2018; Ivanoff et al, 2017; Marinescu et al, 2020; Maske et al, 2021; Özyürek et al, 2017; Plotino et al, 2017; Roperto et al, 2019; Saberi et al, 2020; Sabeti et al, 2018; Spicciarelli et al, 2020) or merely by random allocation into the experimental groups (Chlup et al, 2017; Makati et al, 2018; Mustafa et al, 2020; Reddy et al, 2020). To overcome these sampling limitations, De‐Deus et al (2020) demonstrated that micro‐CT technology is the recommended method to pair‐match extracted teeth based on their anatomical characteristics (Figure 24).…”

“…Two studies using mandibular molars (Silva et al, 2021a), maxillary central incisors, and maxillary first premolars (Spicciarelli et al, 2020) compared the influence of ConsAC (Spicciarelli et al, 2020) and UltraAC (Silva et al, 2021a) to TradAC regarding the cyclic fatigue resistance of reciprocating instruments. In both studies, instruments used in teeth prepared with minimally invasive access cavities were associated with less cyclic fatigue resistance values than in teeth with TradAC.…”

“…No superior fracture resistance in some tooth ( in vitro ) (Augusto et al, 2020; Barbosa et al, 2020; Chlup et al, 2017; Corsentino et al, 2018; Ivanoff et al, 2017; Lima et al, 2021; Maske et al, 2021; Moore et al, 2016; Özyürek et al, 2018; Pereira et al, 2021; Roperto et al, 2019; Rover et al, 2017; Sabeti et al, 2018; Silva et al, 2020, 2021; Spicciarelli et al, 2020; Xia et al, 2020)…”

“…Because of these improved properties, heat-treated high-flexible NiTi instruments can be successfully used not only for the management of root canals with severe curvatures (Bürklein et al, 2012;Filizola de Oliveira et al, 2019) but also to facilitate their insertion in teeth prepared with minimal access cavities since they can be effectively prebent. However, excessive angulation resulted from coronal interferences caused by the access design can increase the stress over the active part of the instrument (Pedullà et al, 2018(Pedullà et al, , 2020, reducing its cyclic fatigue resistance (Silva et al, 2021a;Spicciarelli et al, 2020) and potentially increasing the risk of fracture (Lima et al, 2021).…”

“…Whilst eight F I G U R E 2 2 3D renderings from representative premolars showing (black arrows) the presence of remaining root fillings in the pulp chamber of (a) TradAC and (b) ConsAC after cleaning procedures. It is important to note the presence of root filling remnants at the pulp horns in ConsAC due to the difficulty to clean these areas studies reported greater fracture resistance of teeth with minimal access cavity preparations when compared to TradAC (Abou-Elnaga et al, 2019;Karobari et al, 2021;Krishan et al, 2014;Makati et al, 2018;Marinescu et al, 2020;Plotino et al, 2007;Saberi et al, 2020;Santosh et al, 2021), a total of 18 studies reported no difference among them (Augusto et al, 2020;Barbosa et al, 2020;Chlup et al, 2017;Corsentino et al, 2018;Ivanoff et al, 2017;Lima et al, 2021;Maske et al, 2021;Moore et al, 2016;Özyürek et al, 2017;Pereira et al, 2021;Roperto et al, 2019;Rover et al, 2017Rover et al, , 2020Sabeti et al, 2018;Silva et al, 2020bSilva et al, , 2021bSpicciarelli et al, 2020;Xia et al, 2020) (Table 5). It is likely that these conflicting outcomes can be partially explained by differences in the experimental methods.…”