Is the angulation of mandibular third molars associated with the thickness of lingual bone?

Topographic relationship between root apex of mesially and horizontally impacted mandibular third molar and lingual plate: cross-sectional analysis using CBCT

“…Here, we included 364 mesially and horizontally impacted mandibular third molars and found that 32.97% (120/364) root apexes perforated beyond the outer border of the lingual cortex and 40.28% (145/360) were direct contact with lingual cortical bone. Such incidences were much lower as compared with Tolstunov’s data29, but markedly higher in relative to Emes’s findings26. We reasoned that this discrepancy might associate with different sample size, bias of patient selection, varied criteria of patient inclusion and categorification methods.…”

“…However, Tolstunov L, et al . recently reported the incidence of root perforation in the lingual cortex was much higher (65.5%) as detected by CBCT in 149 patients with 200 partially impacted mandibular third molars29. Here, we included 364 mesially and horizontally impacted mandibular third molars and found that 32.97% (120/364) root apexes perforated beyond the outer border of the lingual cortex and 40.28% (145/360) were direct contact with lingual cortical bone.…”

“…The distribution of spatial relationship between root apex of impacted third molar and lingual plate varied among diverse previous studies262729. Emes and his colleagues reported that only four root apexes of impacted third molars were identified on CBCT images which perforated beyond the lingual plate and directly contacted with lingual soft tissue (Type C) in 32 teeth (31 patients)26.…”

“…The patients included here were strictly filtered and screened according to our inclusion/exclusion criteria to reduce sample heterogeneity as much as possible. Here only these mesially and horizontally impacted mandibular third molars were enrolled largely due to their major prevalence in population35 and intimate topographic relationship between the roots and lingual plate of mandible29. To the best of our knowledge, our sample size might be the largest one to evaluate the spatial relationship between impacted third molars and lingual plate by cross-sectional CBCT images.…”

“…Their data indicated that root apex of impacted third molar can be very close to the lingual plate and sometimes even protruded into soft tissue of mouth floor in 25% cases26. Additionally, Tolstunov and his colleagues reported that fenestration in the lingual plate identified by CBCT scan was more commonly observed than originally expected at the third molar apex region and such fenestration of lingual bone was significantly associated with the angulation of the impacted third molar29. Moreover, from CBCT data of 110 deeply impacted mandibular third molars, the authors reported that 87.3% teeth were classified as lingual position according to their classification based on the deduction values of buccal-lingual alveolar bone thickness13.…”