## 2 Materials and Methods  
1. Patients  
Five patients with geminated central incisors were studied retrospectively. All of the patients were examined at the mixed dentition stages. Their pretreatment demographic and orthodontic information is presented in Table 2. Four of the patients had maxillary geminated central incisors (3 cases--bilateral, and 1 case--unilateral) and one had a mandibular geminated lateral incisor.  
mesiodistal width of the two central maxillary abnormal incisors was 14 mm on average. The panoramic, periapical, and Cone Beam Computerized Tomography (CBCT) views of the upper incisors revealed fused crowns on both central incisors; a single wide root with a single root canal is clearly demonstrated in the CBCT view (Figure 1B,C). A pretreatment lateral cephalometric radiograph analysis revealed a skeletal class II relationship with a retrognathic mandible with a convex profile, a high angle pattern, and a mandibular clockwise rotation with an enlarged lower facial height (Table 3). The maxillary and mandibular incisors were proclined.  
1. SNA (Sella, Nasion, A point) indicates the position of the maxilla mandible (whether or not it is normal, prognathic, or retrognathic);
2. SNB (Sella, Nasion, B point) Indicates the position of the mandible (whether or not it is normal, prognathic, or retrognathic);
3. ANB (A point, Nasion, B point) indicates whether the skeletal relationship between the maxilla and mandible is a normal skeletal class I (+2 degrees), a skeletal class II (+4 degrees or more), or skeletal class III (0 or negative) relationship;
4. Lower facial height to indicate facial proportions;
5. Angle between Frankfort horizontal line and the line intersecting Gonion-Menton;
6. Upper incisors inclination;
7. Lower incisors inclination.  
Figure 1: Geminated upper central incisors, a clinical and radiographic view before treatment. (**A**) Intraoral and extraoral view; (**B**) panoramic, periapical and cephalometric radiographs; (**C**) Cone Beam Computerized Tomography (CBCT) of geminated teeth.  
(c) Treatment Protocol and Technique  
An orthodontic treatment approach that consisted of a distalization and expansion, without premolar extractions was planned. The geminated incisors non-extraction orthodontic conservative technique included 3 components: (1) a maxillary molar teeth distalization of 3-4 mm to exceed the \"super\" class I dental relationship; (2) a maxillary expansion of 3-4 mm per side; and (3) an incisor teeth protrusive inclination of 7-8 degrees. At first, distalization with a pendulum, a noncompliance orthodontic appliance, was started. Its adverse effect of incisor proclination is also favorable in gemination for its contribution to arch length. Thus, cervical head gear aimed to increase distalization, but which limits the incisor proclination was achieved just 3-4 months later. After the class I relationship was accomplished, a bonded pre-adjusted upper fixed orthodontic appliance was used to expand the upper arch. In the other patients an upper arch expansion was started by Hyrax, enabling an upper median diastema opening. A fixed pre-adjusted appliance was immediately bonded to take advantage of the space created in the upper frontal area to alleviate the upper crowding. The Hyrax was removed after 6 months of retention. In the next step, a lower fixed pre-adjusted appliance was performed to achieve arch coordination and additional lower arch expansion. In addition, a slight upper proclination was considered. The main objectives of the treatment modality were: (1) to obtain healthy periodontal tissue while avoiding bone loss in the median region; (2) to meet aesthetic and functional requirements; (3) to reach upper and lower anterior crowding alleviation; and (4) to establish normal overjet and overbite with full alignment of the geminated teeth.