Comparison of guided endodontic access with and without pin fixation in 3D printed teeth with simulated pulp canal obliteration
Introduction: In order to successfully treat an infected root canal system (RCS), it is required to locate all root canals and have an access path to the apex of each canal. This can be challenging in teeth with pulp canal obliteration (PCO), often leading to increased chair time and increased risk of iatrogenic errors. Guided endodontic access (GEA) combines information from a cone-beam computed tomography (CBCT) scan with an intra-oral scan to create a stent. GEA stents with or without fixation pins have been shown to be successful in accurately negotiating a RCS with PCO. Objective: Compare the degree of deviation and difference in 3D offset at the base to apical tip of the drill from the designed access path when a GEA stent with and without pin fixation is used to access tooth #8 with PCO. Materials and Methods: A 3-D printed maxillary model of an anonymous patient had a GEA stent designed using coDiagnonstiX software. The stent extended from tooth #3 to tooth #14 with the guide sleeve over tooth #8. Tooth #8 with no calcification, calcification to the cervical third, and calcification to the middle third of the RCS were designed in the coDiagnostiX software. Tooth #8 will be accessed using a 1.3 mm drill that fits a 1.3 mm sleeve used for both access and pin fixation. 15 of the 30 GEA samples will utilized pin fixation, while the other 15 samples did not utilize pin fixation. Following GEA in all 30 samples a CBCT was taken of each sample. Each post-operative CBCT was aligned with the pre-operative CBCT in the coDiagnostiX software. The coDiagnostiX software was able to calculate the degree of deviation and difference in 3D offset between the base and apical tip of the drill during GEA. Paired t-tests were used to test each group for significant differences in 3D offset between base and tip. Two-way ANOVA was used to evaluate the effects of pin fixation and calcification on the degree of deviation and the deviation of 3D offset of the entry point and tip. Results: There was a significant interaction between use of pin fixation and calcification level on the degree of deviation of GEA. GEA with pin fixation had a significantly larger degree of deviation than GEA without pin fixation with calcification extending to the middle third of the RCS. GEA with and without pin fixation did not have a significant difference when calcification extended to the cervical third of the RCS or no calcification was present. There was a significant interaction between use of pin fixation and calcification level on 3D offset difference. GEA with pin fixation had a significantly larger 3D offset difference than GEA with no pin fixation for calcification in the middle third of the RCS. For GEA with and without pin fixation there was no significant difference when calcification extended to the cervical third of the RCS or no calcification was present. Conclusion: The use of pin fixation did not result in a decrease of degree of deviation or difference in 3D offset during GEA access. It can be concluded that the use of pin fixation is not necessary for GEA of teeth with PCO when a full dentition is present to provide stability and retention of the stent.
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