Approximation and contact of the maxillary central incisor roots with the incisive canal after maximum retraction with temporary anchorage devices_ Report of 2 patients

More documents

Recommendations

Info

496 Chung, Choi, and Kim Fig 3. Posttreatment intraoral photographs, radiographs, and cephalometric superimposition. the patient's consent. The 3D CBCT findings obtained immediately after the treatment and those obtained 36 months after treatment were superimposed by automatic voxel-by-voxel registration at the cranial base (OnDemand3D; Cybermed, Seoul, Korea). 12,13 The 3D superimposition did not indicate any specific changes in the surrounding alveolar bone, the position of the central incisors in contact or approximation with the incisive canal, or the incisive canal itself (Fig 6). No specific symptoms or pain was reported; in general, the probing depth was less than 2 mm, except for the mesiopalatal interproximal gingiva, where the depth was approximately 3 to 4 mm, but it was not associated with bleeding. Patient 2 Patient 2 was a 46-year-old woman with chief complaints of lip prominence and protrusion. Intraoral photographs, radiographs, and cephalograms indicated a skeletal Class II malocclusion with a protrusive profile (Fig 7). To improve the protrusive profile and to obtain a Class I occlusion with ideal overjet and overbite, 4 first premolars were extracted, and orthodontic treatment was begun with 0.018-in slot Roth prescription self-ligating brackets (Tomy International). Two miniscrews (Ortholution) were inserted between the maxillary second premolars and the first molars to reinforce anchorage. The anterior teeth were retracted via enmasse sliding mechanics with elastomeric modules. The duration of the treatment was 28 months. As a result, her profile was improved, and she had a Class I occlusion with ideal overjet and overbite (Table II). The cephalometric superimposition indicated maximum retraction through controlled tipping and intrusion of the maxillary incisors. The total amounts of retraction at the incisor tips of the maxilla and the mandible were 8.5 and 8.0 mm, respectively. A slight apical root resorption of the maxillary incisors was noted after the treatment (Fig 8). Compared with the CBCT images before treatment, the maxillary incisor root apex was approximated to the cortical bone surrounding the incisive canal, which was nearly in contact after retraction (Fig 9, A and B). The 3D superimposition of the CBCT images obtained before and after treatment indicated retraction of the teeth along with remodeling of the surrounding alveolar bone. However, the incisive canal did not show any gross positional changes after tooth movement (Fig 9, C-E). September 2015 Vol 148 Issue 3 American Journal of Orthodontics and Dentofacial Orthopedics
Chung, Choi, and Kim 497 Fig 4. CBCT images of the maxillary arch and the central incisors after maximum retraction: A, axial and B, coronal sections show that the right central incisor root is in contact with the incisive canal; C, sagittal sections of the right central incisor slice passing the incisive canal; D, another slice slightly distal passing the tooth axis; E, sagittal section of the left central incisor slice passing the incisive canal; F, another slice slightly distal passing the tooth axis. The arrows indicate the incisive canal. DISCUSSION The proximity of the maxillary incisor roots to the incisive canal or the possibility of approximation or invasion of the tooth roots into the incisive canal after anterior retraction has not been closely evaluated in the orthodontic literature. The lack of information is possibly because the incisive canal is a midsagittal structure positioned between the roots, and its dimension or morphology is not clearly defined by conventional 2-dimensional radiographs. However, with the help of 3D imaging, the incisive canal was noted as an anatomic structure that may be associated with orthodontically induced inflammatory root resorption of the maxillary central incisors during maximum retraction. The maxillary central incisors are most frequently involved in orthodontically induced inflammatory root resorption, which is reportedly associated with patientrelated risk factors such as genetic influence, root morphology, root proximity to the cortical bone, alveolar bone density, and type of malocclusion, and with orthodontic treatment-related risk factors such as treatment duration, magnitude of force, and amount of apical root movement. 14,15 Although force levels about 150 g of force were used for en-masse retraction in our patients, it is possible that the apparent root resorption was mainly related to the large amounts of anterior retraction and root movement to maintain anterior torque. However, in patient 1, the differences in the levels of root resorption between the right and left central incisors were quite evident with distinct morphologic features, whereas the patient-related and treatment-related American Journal of Orthodontics and Dentofacial Orthopedics September 2015 Vol 148 Issue 3
Page 1 and 2: CLINICIAN'S CORNER Approximation an
Page 3: Chung, Choi, and Kim 495 Fig 2. Pre
Page 7 and 8: Chung, Choi, and Kim 499 Fig 7. Pre
Page 9 and 10: Chung, Choi, and Kim 501 Fig 9. CBC

Approximation and contact of the maxillary central incisor roots with the incisive canal after maximum retraction with temporary anchorage devices_ Report of 2 patients

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?