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Evaluation of anatomical relationships in the mandibular third molar region based on its angulation and depth of impaction: a CBCT-based study

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Abstract

Purpose

The aim of this study is to evaluate the relationship between the inclination/impaction depth and root proximity to the inferior alveolar canal/lingual plate on a millimeter scale using CBCT scans.

Methods

340 CBCT scans of the mandibular third molar (M3) of 219 patients were evaluated for this cross-sectional study. After adjustment of the 3D orientation of the individual’s jaws, the study variables including the angulation between M3 and second molar (M2)/occlusal plane (OP), and the distance of mesial (M)/distal (D) roots of M3 from the inferior alveolar canal (IAC) and lingual plate (LP) were measured. Winter’s classification was used for the specification of teeth angulation. The vertical position of each M3 was then evaluated using the 3D view window (based on Pell & Gregory classification). The Spearman correlation coefficient was used for reporting the correlation between quantitative variables. The One-way ANOVA test and the Welch analysis were used for inter-group comparisons. Finally, a multivariant analysis of variances was performed.

Results

Most third molars had a mesioangular inclination (52.1%), and vertical inclination (25.9%) was in second place. There was no significant correlation between angulation and age or the D/LP. A strong positive correlation between M3:M2 and M3:OP was observed (0.983). Furthermore, there was a weak negative correlation between M/IAC or M/LP and angulation (− 0.16 and − 0.13, respectively). Concerning Winter’s classification, the relationship between D/IAC and angulation was statistically significant (P = 0.003). Furthermore, teeth in position A had lesser inclination compared to those with B or C positions. Multivariate analysis revealed that there was no statistically significant relationship between particular combinations of inclination-impaction depth and proximity of the M3 roots to the IAC or LP (P = 0.211).

Conclusions

The findings of the current study revealed that there is a strong correlation between M3:M2 and M3:OP. The D/IAC was the only variable that had a significant relationship with the angulation of these teeth. Moreover, the roots of horizontally inclined teeth with position A were the closest to the LP and the farthermost to the IAC.

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Author information

Authors and Affiliations

  1. Oral and Maxillofacial Radiology Department, School of Dentistry, Shahid Beheshti University of Medical Sciences, Tehran, Iran

    Zahra Vasegh

  2. Oral and Maxillofacial Surgery Department, School of Dentistry, Shahid Beheshti University of Medical Sciences, Tehran, Iran

    Pedram Bakhshaei

  3. Orthodontics Department, School of Dentistry, Babol University of Medical Sciences, Babol, Iran

    Morteza Jahanbani

  4. Orthodontics Department, School of Dentistry, Tabriz University of Medical Sciences, Tabriz, Iran

    Reza Mahmoudi Anzabi

Authors
  1. Zahra Vasegh
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  2. Pedram Bakhshaei
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  3. Morteza Jahanbani
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  4. Reza Mahmoudi Anzabi
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Contributions

Z.V. designed the work and analyzed the data. P.B. wrote the main manuscript text and revised the article critically for important intellectual content. M.J. owned the conception of the work, collected the data, and prepared tables and figures. R.M. wrote the main manuscript text.

Corresponding author

Correspondence to Morteza Jahanbani.

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The study was approved by the ethics committee of Shahid Beheshti University of Medical Sciences (IR.SBMU.DRC.REC.1400.056).

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The authors declare no competing interests.

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Vasegh, Z., Bakhshaei, P., Jahanbani, M. et al. Evaluation of anatomical relationships in the mandibular third molar region based on its angulation and depth of impaction: a CBCT-based study. Oral Maxillofac Surg 28, 613–622 (2024). https://doi.org/10.1007/s10006-023-01178-y

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