Gender and Growth Variation in Mandibular Buccal Shelf Area for Mini-implant Placement

Objectives: The primary objective of the study was to quantitatively analyze the width and height of the mandibular buccal shelf area (MBS) at three different potential locations for mini-implant placement. Additionally, our aim was to compare and contrast the bone parameters of the MBS in males and females in three different facial type (hypodivergent, normodivergent, and hyperdivergent).
Methods: In this retrospective CBCT study, a total of 678 subjects were analyzed in three different facial types (Fig 1). The measurements were made at six different coronal sections as follows: mandibular first molar distal root, second molar mesial root and second molar distal root (bilaterally). The roof of the inferior alveolar canal was used as the reference point to measure the height of the buccal shelf area (Fig 2). The intra-observer reliability was assessed by randomly selecting 30 subjects and taking measurements 1-month apart.
Results: No significant difference (P >0.05) was found in the bone width between genders. Bone width increases and height decreases (P< 0.0001) as we move distally from the first molar distal root to second molar distal root in all the three different facial types irrespective of age or gender. The hypodivergent facial type had significantly more bone width than hyperdivergent facial type at all the three locations in both males and females. The hypodivergent facial type had significantly less (P< 0.0001) bone height than the hyperdivergent group, at all the three locations irrespective of age or gender.
Conclusions: The ideal site for MBS mini-implant is the buccal area of the distal root of mandibular second molars. Hypodivergent patients have more width and less height of MBS compare to hyperdivergent.