Cortical bone thickness for miniscrew placement in adults

Abstract

We read with great interest the article that documents cortical bone and ridge thickness (Horner KA, Behrents RG, Kim KB, Buschang PH. Cortical bone and ridge thickness of hyperdivergent and hypodivergent adults. Am J Orthod Dentofacial Orthop 2012;142:170-8). Cortical bone and ridge thickness help to determine the stability of temporary skeletal anchorage devices, as well as implant diameter, length, and the presence of inflammation. Miniscrew implants are widely used to provide anchorage in orthodontics because they are easy to insert and remove. We congratulate the authors for their efforts. However, we have questions about the article. The authors reached a conclusion that maxillary lingual and mandibular buccal cortical bone thicknesses increase from posterior to anterior. However, this is not consistent with the statistics in Table III and the results on page 174; the posterior buccal sites tended to have thicker cortical bone than did the anterior sites, but only the differences in the mandible were statistically significant. As mentioned in the Discussion section, since strains from musculature primarily affect the cortical bone, the medullary thickness shows no significant difference between hypodivergent and hyperdivergent subjects. However, occlusal forces not only affect cortical bone, but also influence cancellous bone. Although medullary thickness doesn't show any significant differences, is the density of the cancellous bone also not affected by the facial divergence? Another consideration is that only hypodivergent and hyperdivergent subjects were studied in the article. What about patients with average angles? Because the stability of temporary skeletal anchorage devices is a concern, we had hoped that the article could be of some help in our clinic. Cortical bone and ridge thickness of hyperdivergent and hypodivergent adultsAmerican Journal of Orthodontics and Dentofacial OrthopedicsVol. 142Issue 2PreviewThe purpose of this study was to assess differences in dentoalvolar cortical bone thickness between hyperdivergent and hypodivergent young adults. Full-Text PDF Author's responseAmerican Journal of Orthodontics and Dentofacial OrthopedicsVol. 143Issue 2PreviewIt is gratifying to know that others are carefully reading the orthodontic literature, especially when it is one of your own articles. Dr Cao is correct in noting that the cortical bone on the lingual aspect of the maxilla did not follow the same pattern as that on the buccal aspect of the mandible. Thus, conclusion number 4 should be changed to read, “Mandibular buccal cortical bone thickness decreases from posterior to anterior.” We apologize for this oversight and are glad to have it corrected. Full-Text PDF