13 March 2024

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Removal of fiber endocanal posts: guided technique vs conventional freehand technique

Lara Figini

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When due to periapical pathologies there is a need to provide root canal retreatment in teeth treated endodontically and reconstructed with a post, the first step is the removal of the post in order to access the endodontic system. The endocanal posts can be metallic or made of carbon, glass or silica fibre, and depending on the material the removal procedures must be different. Removing a metal post and its cement often takes a long time with a high risk of damaging the remaining tooth structure. However, when removing metal posts, the operator can easily identify the post from the root dentin. Glass or silicon fiber posts, on the other hand, are difficult to distinguish from the root dentin, especially in depth, even with the aid of a dental microscope. Furthermore, due to their lower modulus of elasticity, fiber posts cannot be removed predictably with ultrasound. Great care must be taken when removing the posts to avoid aberrant angulations, root perforations, crack formation and root fractures. Round burs, ultrasonic tips and removal kits specifically designed to remove fiber posts have been commercially offered. However, ultrasound is still the most commonly used device for this purpose but has disadvantages, such as generating heat and causing cracks in the dentin, all factors that reduce the fracture resistance of the roots. Alternative methods have therefore been devised, including guided endodontics. Guided endodontics can be static or dynamic. Static guided endodontics requires the creation of three-dimensional (3D) printed models using images obtained through cone beam computed tomography (CBCT) scans and virtual imaging software for access cavity preparation and endodontic surgery. This technique appears to be an effective approach to obtain a result with an optimal clinical picture, with the advantage of being extremely accurate and rapid, as well as providing greater preservation of the tooth structure, reducing the risk of iatrogenic damage. Dynamic navigation systems (DNS) instead use computer-assisted guided technology, with cameras and motion detection devices connected to the dental handpiece and the patient. The system continuously compares the path created within the tooth or bone, with a machining path virtually planned using software that interprets CBCT images of the teeth and bones.

Materials and methods

In an in vitro study, published on the International Endodontic Journal,  March 2023, the authors compared the effectiveness of fiber post removal by comparing the guided static navigation technique to the conventional freehand technique with ultrasound by both experienced operators how inexperienced. Forty-eight extracted single-rooted human premolars were endodontically treated and filled. A fiber post was cemented into all 48 teeth, then the samples were randomly divided into the following two groups:

- GROUP 1: in which the removal of the pins was performed via a guided static navigation procedure with drills (guided navigation group);

- Group 2 or ultrasonic group where freehand ultrasonic tips were used for pin removal.

The authors evaluated the treatment whether performed by experienced or inexperienced operators, successful achievement of gutta-percha, the time required to remove the entire post, the presence of lateral root perforations, and the amount of root dentin removed. The Kolmogorov-Smirnov test was used to examine the data; the anova test was used to compare significant differences between groups; and Tukey's test was used for all comparisons. The significance level was set at 0.05.

Results

In the guided static navigation group, gutta percha was achieved significantly more frequently than in the unguided group (p<.05). The static navigation approach took significantly less time than the unguided approach to reach the gutta-percha (p<.05). Total pin removal was significantly different between the two groups (p<.05), but there was no significant difference between the experienced and inexperienced groups in the static navigation group (p>.05). The appearance of perforations was found to be more associated with the unguided group. The mean total dentin loss in the unguided group in all directions was found to be 0.39 (±0.17) mm, with 0.25 (±0.09) mm for experts and 0.42 (±0.09) 16) mm for inexperienced operators.

Conclusions

From the data of this study, which must be confirmed in other similar in vitro and in vivo studies, it can be concluded that compared to a conventional ultrasound technique for the removal of fiber posts, the method of static navigation guided with drills is more conservative , with greater saving of root dentin, guarantees quicker access to the gutta-percha, and requires less overall time to remove the posts and with fewer complications.

Bibliography

A laboratory study comparing the static navigation technique using a bur with a conventional freehand technique using ultrasonic tips for the removal of fiber posts

Francesc Abella Sans, Zeena Tariq Alatiya, Gonzalo Gómez Val, Venkateshbabu Nagendrababu, Paul Michael Howell Dummer, Fernando Durán-Sindreu Terol, Juan Gonzalo Olivieri

International Endodontic Journal March 2024, Volume 57, Issue 3, Pages: 355-368