## 4 Discussion  
Double teeth may involve an unaesthetic appearance and space problems, making normal teeth alignment impossible and creating functional disorders and difficulties with maintaining oral hygiene. Three treatment alternatives for the gemination phenomenon were considered (Table 1). The first two alternatives are multidisciplinary and based on a prosthodontic approach; thus, presenting an extended and expensive treatment option until permanent crown restoration is performed aged 18 or later. The first option, involving surgical extraction of the geminated tooth and later prosthodontic treatment, can be especially tempting in cases where a geminated or fused tooth is present, to avoid asymmetry. The future restoration may include a ceramic crown [6] via implant placement or an acid-etched bridge. An adverse effect of such a treatment plan is early alveolar bone loss at the anterior aesthetic area, due to tooth extraction at a young age before full skeletal maturation is achieved. In cases where there are two geminated anterior incisor extractions, extensive bone loss is anticipated, requiring extensive bone augmentation, which is essential to support future implants. Therefore, extractions of teeth from the anterior area should be avoided. Decoronation--removal of the tooth crown in infra-occlusion--leaving the root in its alveolus to be replaced by bone, is aimed at preserving the alveolar ridge for a future prosthodontic solution [11; 12]. It can also serve as another option for the geminated tooth. Although this option can be advantageous compared to surgical extraction, it can compromise an orthodontic treatment, if needed. the increased mesiodistal width of the root can either prevent good root approximation and alignment [13] or hinder tooth movement into the decoronated site until complete root resorption occurs. The second solution is a combined prosthodontic-endodontic treatment. A mesiodistal slicing of the mega-crown is performed, usually followed by a root canal treatment and prosthetic restoration. The endodontic approach may interfere with the conservative treatment principle since the success rate of root canal treatment is 82.8-97.3% [14]. In addition, geminated teeth have a crown-root dilaceration [15], or complicated root canal morphology [16]. Root resection, which was proposed in fused teeth with wide crowns [3; 17], can be contradicted in geminated teeth because a single pulp chamber is present. Literature reports of two cases of geminated teeth with root resection followed later by reshaping and restoration exist [18; 19]. Orthodontics is the third treatment modality, aimed at obtaining healthy periodontal tissue and avoiding bone loss, which is most likely to happen in the median region following the extraction of adjacent teeth [20]; thus, this option enables both functional and aesthetic results. The success of orthodontic treatment is dependent on a few parameters; one of these is a correct arch relationship [21]. However, the ratio between the available maxillary and mandibular tooth sizes is not precise in gemination. In the first three presented cases, both Bolton's overall and anterior ratios were reduced by more than two standard deviations from the expected ratio. In such cases, with significant discrepancy from the Bolton's mean values, incorporation of the findings into an orthodontic treatment plan is essential to meet the patients' expectations [14; 22; 23]. In the presented cases, the skeletal cephalometric measurements are described in an increased ANB angle; and this demonstrated maxilla mandibular discrepancy is derived from the relative protrusive maxilla and retrusive mandible. These skeletal relationships enable a dento-alveolar compensation, which could resolve the tooth size discrepancy in tooth width between the two arches. In the presented cases, space is created by the non-extraction means of upper distalization, expansion, and minor teeth proclination.