Is the presence of Simonart's band in patients with complete unilateral cleft lip and palate associated with the prevalence of missing maxillary lateral incisors? Mar  ılia Sayako Yatabe, a Daniela Gamba Garib, b Guilherme Janson, c Raquel Silva Poletto, d and Terumi Okada Ozawa e Bauru, S~ ao Paulo, Brazil Introduction: The aim of this study was to compare the prevalence of agenesis of the maxillary lateral incisors in the cleft area of patients with unilateral cleft lip and palate with and without Simonart's band. Methods: A sample of panoramic radiographs of 121 patients with a mean age of 7 years was divided into 2 groups: group 1 included 60 patients with Simonart's band, and group 2 included 61 patients without Simonart's band. Patients with syn- dromes were not included. Chi-square tests were used for intergroup comparisons (P \0.05). Results: In the pooled subgroup, the prevalences of maxillary lateral incisor agenesis, supernumerary maxillary lateral incisors, 1 maxillary lateral incisor mesial to the cleft, and 1 maxillary lateral incisor distal to the cleft were 40.5%, 12.5%, 8.2%, and 38.8%, respectively. In group 1, these frequencies were 35%, 10%, 6.7%, and 48.3%; in group 2, they were 45.9%, 13.1%, 11.5%, and 29.5%. There was a statistically significant difference between the groups for the prevalence of a maxillary lateral incisor distal to the cleft. Conclusions: The presence of Simonart's band is associated with a higher frequency of maxillary lateral incisor development in the maxillary process. (Am J Orthod Dentofacial Orthop 2013;144:649-53) I t has been proposed that clefting is part of a complex malformation associated with other dental anoma- lies. 1 According to Hoffmeister's genetic study, some microsymptoms such as hypodontia, hyperodon- tia, fusion of teeth, and twin formation have a common genetic background. Since the cleft is located at the border of the primary and secondary palates, dental anomalies in this area are common. 1 Previous embryologic studies have demonstrated that the maxilla is derived from the maxillary process, which originates from the first pharyngeal arch, called the maxillary growth center, and the premaxilla, which originates from the frontonasal prominence and part of the lateral nasal prominence. 2 During prenatal devel- opment, the medial part of the maxillary process delivers material to the future premaxilla. 3 Therefore, after ossi- fication, the incisive suture delimitating the posterior and anterior segments of the maxilla is positioned more mesially than is the fusion site between the pre- maxilla and the maxillary processes. 2 In 3-dimensional reconstructions, it was possible to observe 2 thickenings of the dental epithelium origi- nating independently from the medial nasal and maxil- lary processes separated by a narrow groove. 3 The fusion site of the dental epithelia was detectable as a furrow on the germ of the lateral incisor. 3 Therefore, the mesial half of the maxillary lateral incisor might derive from the premaxilla, and the distal half of maxil- lary lateral incisor might derive from the maxillary process. This presumed double origin of the lateral incisor could explain the high frequency of dental anomalies of number observed in patients with cleft lip and pal- ate. Those with complete unilateral cleft lip and palate might have agenesis of the maxillary lateral incisors in the cleft region, supernumerary maxillary lateral From the University of S~ ao Paulo, Bauru, S~ ao Paulo, Brazil. a Postgraduate student, Department of Orthodontics, Bauru Dental School. b Associate professor, Department of Orthodontics, Hospital of Rehabilitation of Craniofacial Anomalies, Bauru Dental School. c Professor, Department of Orthodontics, Bauru Dental School. d Resident, Hospital of Rehabilitation of Craniofacial Anomalies. e Head, Dentistry Division, Hospital of Rehabilitation of Craniofacial Anomalies. All authors have completed and submitted the ICMJE Form for Disclosure of Po- tential Conflicts of Interest, and none were reported. Address correspondence to: Mar  ılia Sayako Yatabe, Alameda Oct avio Pinheiro Brisolla, 9-75, 17012-901, Bauru, S~ ao Paulo, Brazil; e-mail, msyatabe@ yahoo.com.br. Submitted, December 2012; revised and accepted, June 2013. 0889-5406/$36.00 Copyright Ó 2013 by the American Association of Orthodontists. http://dx.doi.org/10.1016/j.ajodo.2013.06.018 649 ORIGINAL ARTICLE