The Correlations Between Cone-beam Computed Tomography-based Measurements And Cephalometric Measurements Of The Palatal Bone Thickness

In clinical orthodontics, anchorage control is one of the most significant keys for successful accomplishment. In order to get the proper anchorage, numerous anchorage devices are used for more than a century. Extraoral anchorages such as headgears or facemasks are the most powerful tools but they have a d i s a d v a n t a g e that their effectiveness depends on the patient compliance. Though intraoral anchorages, such as transpalatal arch, nance arch, lingual arch and so on, do not require patient compliance, anchorage loss happens occasionslly. In 1980 s, Creekmore and Eklund presented a idea of skeletal anchorage in orthodontic field. In 1990 s, orthodontic anchorage devices, such as miniscrews and mini-plates, were newly developed and these devices have been well accepted in all over the world. Because the palate b o n e w i t h dense hard tissues are devoid of major blood vessels and nerves, scholars consider that these areas are f i t f o r i n s e r t i o n of mini-implant anchorage. Palatal bone thickness is a critical factor which effects the primary stability of mini-implant anchorage during orthodontic treatment. Before the CBCT is introduced in clinical applications, panoramic radiograph and lateral cephalograph are often used for diagnosis and treatment planning in orthodontics, so the aim of our study is to estimate the relationships between cone-beam computed tomography-based measurements and cephalometric measurements of the palatal bone thickness.Methods: To take CBCT images and cephalograms of 31 malocclusion patients in the preliminary diagnosis. Measurements of anterior-posterior were obtained from the touch points between the first and second premolars to the touch points between the first and second molars of bilateral maxillary. In the CBCT-based images, the eccentric distance were set from 1.5mm to 10 mm.SPSS19 was used to examine the differences between the measurements.Results: In the P1P2 and P2 areas,the CBCT-based measurements of palatal bone thickness at 1.5mm and 5mm off-center were significantly less than the cephalometric measurements. The 10 mm off-center measurements and cephalometric did not differ significantly in any areas. Both the CBCT-based measurements at every eccentric distance and cephalometric of palatal bone thickness declined from P1P2 to M1M2.Conclusion: A s palatal bone outline, t he palatal bone at 10 mm off-center is the most close to cephalograms. I n t h e P 1 P 2 a r e a, t he palatal bone at 5 mm and 7.5mm off-center was more relatively safer than other areas in the process of embedding mini-implants.