Tomographic characterization of the Gubernacular Canal in the eruption of second and third molars
Authors: Khouri Micheline S , Neto Idalisio Idalisio Aranha , Rodrigues Lizandra G , Ribeiro Isabela C , Manzi Flavio Ricardo , Lima Izabella Lucas Abreu , Miranda Diogo Azevedo , Silva Amaro Ilidio Vespasiano , Alves Tatielly Karina Costa 
Published: March 2023

Abstract
Aim: To evaluate, by Cone-Beam Computed Tomography (CBCT), the dimensions and positions of the Gubernacular Canal (GC) of the maxillary and mandibular second and third molars in the initial stages of tooth formation.
Study design: To achieve this, this study used CBCT images of 100 fully intraosseous teeth, in the development stages, between stages 2 and 7 of Nolla, divided into four groups: maxillary and mandibular second and third molars, with 50 teeth evaluated in each tooth group. This study evaluated the presence of GC, the occurrence of the obliteration and/or stenosis, curvature, height, thickness, length, diameter, and angulation in relation to the corresponding tooth and in relation to the occlusal plane, the GC position in relation to the studied molars, the development stage, and the follicular space. The linear and angular measurements were obtained by two previously trained and calibrated examiners, and the intra- and interexaminer agreements were calculated. Statistics tests were applied to all of the evaluations, adopting a significance level of 5%.
Results: The GC relation with the maxillary and mandibular teeth behave distinctly, highlighting the positioning of the second and third molars, where the maxillary molars are located further away from the alveolar bone ridge in the vertical position, while the mandibular molars can be found in the mesioangular position.
Conclusions: The different relation of the sample’s GC interferes in the positioning of the teeth. The maxillary molars are located further away from the alveolar bone ridge, while the mandibular molars are more inclined, illustrating their impaction.
Clinical Relevance: There are many complications that can occur during a tooth’s eruption process. Among these are such anomalies as inclusion and dental impaction, which are routine situations in dental clinical practice and which present a certain potential to generate other problems associated with them, such as the development of pathological conditions, like cysts and tumors, tooth reabsorptions, pericoronitis, among others.
Materials and Methods
This study was developed in the Department of Dentistry of the Coração Eucarístico Campus of the Pontific Catholic University of Minas Gerais (PUC-Minas), in Belo Horizonte, Brazil. This study was submitted and approved by the PUC-Minas Research Ethics Committee (CAAE: 29723020.9.0000.5137). The consent form was obtained from all patients who had their tomographic images evaluated by this research.
Sample Selection
The present study is a retrospective cross-sectional study. This study used 100 CBCT exams, 50 maxillary and 50 mandibular, to obtain 50 maxillary and mandibular second and third molars in similar development stages. The convenience sample was collected from patients who sought out dental services with different dental needs and ended up needing CT exams for tooth diagnosis.
As an inclusion criteria, the images used for this analysis are of patients that presented, at the moment of the exam, second and/or third molars in development stages, that were fully intraosseous, between stages 2 and 7 of Nolla.11
Discarded were the exams in which the second and third molars were in the very initial development stages (stage 0 or 1 of Nolla) or very advanced stages (above 7), or when the second and third molars were in the process of advanced eruption, in which the follicular space is in such a proximity with the alveolar bone crest that it becomes impossible to distinguish the dimensions of GC. In addition, the CT exams that presented artefacts of movement were not included, as they presented distortions in the images. The CBCT exams were acquired using the Carestream 8100 and 9000 (Carestream Health, Inc., Atlanta, GA, EUA), where the exhibition parameters were selected according to each patient and clinical recommendation. All of the images were adequate as regards the aspects of density, contrast, and sharpness for the evaluation of the researched structure.
Clinical trial registration number: 29723020.9.0000.5137