10 December 2021

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Minimally invasive access cavity and reduced root canal shaping: how do they affect the biomechanics of endodontically treated elements?

Simona Chirico

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With the introduction of nickel-titanium instrument and of the straight-line access there was an increasing amount of success rate of endodontic treatment. Minimally invasive access in endodontics (MIE), in fact, guarantees the integrity of  tooth structure and reducing the loss of dental hard tissue, such as adopting minimized endodontic access cavity and endodontic instrument with smaller taper in endodontic treatment. . Although MIE reduced the removal of dental hard tissue, whether it decreased the failure risk of endodontically treated teeth remained unknown. However, some shortcomings are inevitable. 

In a study published by Wang et al on Journal of Endodontics, they decided to investigate the influence of access cavities and tapers of canal preparations on fracture resistance of endodontically treated first molars by finite element method and Weibull analysis. 

Materials and Methods

 On the basis of the microcomputed tomography data of maxillary first molar, the models of endodontically treated teeth with conservative endodontic cavity, traditional endodontic cavity, and 4 tapers of canal preparations (0.02, 0.04, 0.06, and 0.08) were created. Four static loads (800 N in total) were applied vertically to the contact points. The stress distributions of maximum principal stress were recorded and analyzed. Weibull analysis was performed to analyze the failure risk in enamel and dentin. 

Results

The stress distributions of maximum principal stress on occlusal surfaces were similar. In cervical region, the tensile stress was mainly concentrated on mesiobuccal root and root furcation. The finite element analysis and Weibull analysis showed that conservative endodontic cavity significantly reduced the maximum principal stress in cervical region and the failure probability, compared with traditional endodontic cavity. No significant difference was detected among tapers of prepared canals. 

Conclusions

Preserving coronal dentin by using conservative endodontic cavity significantly reduced the concentration of tensile stress and the failure probability of dentin, although the maximum principal stress and failure probability were less affected by taper of canal preparation.

For additional information: Effect of Access Cavities and Canal Enlargement on Biomechanics of Endodontically Treated Teeth: A Finite Element Analysis