Quantitative Assessment of Posterior Maxillary Arch for Orthodontic Mini-screw Insertion Using Cone Beam Computed Tomography- a Cross Sectional Analysis

Abstract Background and aimThe aim of this study is to assess the cortical bone thickness and inter-radicular distance between posterior maxillary teeth using Cone Beam Computed Tomography (CBCT).Methods and materialCone beam computed tomography records of 35 patients (70 quadrants) from maxilla were evaluated. The images were analyzed using NNT viewer Software (Version 23). The measurements were made on axial sections at 2, 4, 6 and 8 mm from the CEJ. The optimal sites were defined in terms of (a) mesiodistal palatal or buccal inter-radicular distance, (b) alveolar cortical bone thickness and (c) palatal or buccal safe depth of bone for mini-screw insertion. Descriptive statistics, paired T-test and repeated measure ANOVA were used to analyze the data.ResultsThe mean buccal inter-radicular distance was lowest between first and second molar (2.44 mm) and highest between first and second premolar (3.28 mm). The mean palatal inter-radicular distance was lowest between first and second premolar (3.64 mm) and highest between second premolar and first molar (5.30 mm).The mean buccal safe depth was lowest between canine and first premolar (1.96 mm) and highest between first and second molar (2.61 mm). The mean palatal safe depth was lowest between second premolar and first molar (3.35 mm) and highest between first and second molar (3.56 mm). The thinnest and thickest buccal cortical thickness was detected on canine and first molar (1.04 mm) and on the second premolar and second molar (1.56 mm). ConclusionThe quantity and quality of the maxillary alveolar process is an important factor to decide where to insert the orthodontic mini screws, necessitating careful preoperative evaluation.

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Comparative Evaluation of Cortical Bone Anatomy of Mandibular Buccal Shelf for Mini Implant Placement in Different Facial Divergence: A Cone Beam Computed Tomography Study

The Journal of Indian Orthodontic Society ◽

10.1177/0301574220932265 ◽

2020 ◽

Vol 54 (4) ◽

pp. 325-331

Author(s):

Kalyani Trivedi ◽

Bharvi K Jani ◽

Sagar Hirani ◽

Mansi V Radia

Keyword(s):

Computed Tomography ◽

Cortical Bone ◽

Cone Beam Computed Tomography ◽

Cone Beam ◽

Bone Surface ◽

Bone Thickness ◽

Second Molar ◽

Cortical Bone Thickness ◽

Implant Placement ◽

Alveolar Crest

Aim: The purpose of this study was to use measurements from cone beam computed tomography scans to quantify the cortical bone thickness of mandibular buccal shelf region and preferable site for buccal shelf implant placement in 10 hyperdivergent and 10 hypodivergent patients. Method: 20 cone beam computed tomographies were equally divided based on divergence. 6 sites were examined: mesial of first molar (6M), middle of first molar (6Mi), interdental between the first and second molar (Id), mesial of second molar (7M), middle of second molar (7Mi), and distal of second molar (7D). The study quantified the mandibular buccal shelf relative to its angle of slope, the cortical bone thickness measured perpendicular to the bone surface, the amount of cortical bone 30° angle to the bone surface. The cortical bone thickness was measured perpendicular and at a 30° angle at 3, 5, and 7 mm from the alveolar crest. Result: Significant change is seen at the buccal shelf slope at 6M ( P = .001) and further increase in this angle till 7D ( P = .003). Mean amount of cortical bone for hyperdivergent group at 7D is 4.77 ± 0.68 mm and for hypodivergent group is 3.86 ± 0.70 mm. Statistically significant differences were noted at insertion site at 90° and 30° for both groups at 3, 5, and 7 mm from the alveolar crest. Conclusion: Preferable site for buccal shelf implant placement is distal to the mandibular second molar. The maximum amount of cortical bone is found distal to the second molar 7 mm vertically from alveolar crest when the buccal shelf implant is placed at 30° angulation for hyperdivergent group.

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