Evaluation of cortical bone thickness of mandible with cone beam computed tomography for orthodontic mini implant installation

Seyed Hossein Moslemzade, Yusef Kananizadeh, Amin Nourizadeh, Aydin Sohrabi, Mehrdad Panjnoosh, Elnaz Shafiee


Background: Achieving maximum anchorage without movement of the teeth in anchorage unit has been a great challenge in orthodontics and the success of the treatment plan highly depends on it. In this case, using orthodontic mini-implants can make a huge difference. The objective of this retrospective study was to measure thickness of cortical bone at prospective mini-implant placement sites in mandible in order to understand stability aspects of mini-implant placement by using cone-beam computed tomography (CBCT) images.

Materials and Methods: Initial 3-dimensional images of 40 adult patients were studied. The cortical bone thickness was obtained at the alveolar processes from canine to second molar at 5 different vertical levels from the cementoenamel junction (CEJ). To determine the cortical bone thickness, tangent lines were drawn buccolingually to the roots in axial section and a third line was drawn from the middle of these two lines, and the cortical bone thickness was measured where the third line crossed the buccal cortex.


Results: Mandibular and buccal cortical bone thicknesses were 0.79 to 2.49 mm, respectively. There was a statistically significant increase from the CEJ to the apex (P<0.001), while this increase was not statically significant at interdental area of teeth #3 and #4. Comparing the 4 mm section in all sites showed significant increase from anterior to posterior.

Conclusion: Based on our results, the cortical bone thickness mostly follows a pattern and depends on the interradicular site rather than individual differences.



Key words: Cone-beam computed tomography; orthodontic anchorage procedures

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