Au Sasaki, Mai Fujimoto, Kouta Fujimoto, Rei Shinagawa, Takuya Sonokawa, Toru Takusagawa, and Naoto Sudaa
What did the authors aim to do in this study?
The primary aim of this case report is to describe the successful orthodontic management of a 12 - year old Japanese girl with skeletal malocclusion in combination with severe root resorption of the maxillary anterior teeth, which was caused due to ectopic eruption of the canine teeth.
How did the authors evaluate & plan the treatment?
A 12- year old female patient with bilaterally impacted maxillary canines and a distally inclined maxillary left lateral incisor reported to the clinic and on clinical examination, it was revealed that she had a skeletal class III intermaxillary relationship with a prognathic mandible and a low clinical FMA. The radiographic examination revealed mesially inclined bilateral maxillary canines surrounded by cyst - like clear radiolucent areas. Severe root resorption was seen in the right central incisor and the bilateral lateral incisors.
Pretreatment intraoral & facial photographs
Pretreatment radiographs (A) Panaromic radiograph, (B) CBCT. 3D reconstructed images & frontal slice images
Because of this, the maxillary right central incisor and left lateral incisor, had to be extracted initially, and the traction of the bilateral canines was planned to replace the extracted teeth. Extraction of the right lateral incisor was also required, and transplantation of an extracted mandibular tooth was planned before the initiation of the alignment of the mandibular arch. Because the patient was only aged 12 years and had a skeletal Class III intermaxillary relationship with a protruded mandible, alignment of the mandibular arch and extraction of the mandibular teeth were planned for after further mandibular growth. The maxillary right deciduous second molar was extracted to induce a normal eruption of the distally tipped maxillary right second premolar.So, the authors planned to extract the right maxillary incisor and both the lateral incisors. A traction force was applied to the maxillary right and left canines toward the extracted right central incisor and left lateral incisor, respectively using a lingual arch.
How did the treatment progress?
A lingual arch was placed in the maxillary arch, and traction of the bilateral canines was initiated at the age of 12 years, 4 months. Ten months later, the right canine and the left canine had moved into the positions of the extracted right central and the left lateral incisors, respectively. The mesial tipping of both canines had improved but was still observable in the radiographs. The short roots of the mandibular incisors were noted. The maxillary right second premolar had erupted after the extraction of the deciduous right second molar. During the traction of both maxillary canines, her mandibular growth was mainly downward, and alignment of both arches was initiated with a multibracket appliance at the age of 14 years, 1 month.
Facial & intraoral photographs after canine retraction
The mandibular right first premolar was extracted. Before extraction, CBCT images were taken and used for a 3D simulation for tooth transplantation. Using CBCT images, a resin replica of the mandibular right first premolar was fabricated by a 3D printer with 50 mm of stacking pitch. Because this replica was used to prepare the extraction socket of the maxillary right lateral incisor immediately before the transplantation, the used resin material had to be harmless but not necessarily to be biocompatible. The labiolingual width of the extracted alveolus was insufficient for transplantation of the mandibular right first premolar, and it was decided to rotate the donor tooth by 90 at transplantation. A 0.018 x 0.025-inch stainless steel wire was placed as an initial wire to stabilize the transplanted tooth, and it was bent so that it could be placed passively to all the maxillary teeth. This wire was placed for 16 weeks until the mobility of the transplanted tooth was within the physiological range, and it was then changed to a light continuous nickel-titanium wire.
Transplantation of the mandibular right first premolar to the extraction socket of the maxillary right lateral incisor. (A) Fabrication of the replica (right) of the mandibular right first premolar from CBCT(left). (B) Extraction of the maxillary right lateral incisor (C) Schema of the donor tooth and recipient socket & planning of the donor tooth rotation by 90 deg. (D) Trial of the rotated replica into the extracted socket (E) Extraction of the mandibular right first premolar (F) Donor tooth placed in the prepared recipient site (G) Fixation of the donor tooth with 0.018 x 0.025 inch stainless steel wire.
The transplanted mandibular first premolar had completed the entire root formation, and the root canal treatment was performed 2 weeks after transplantation. The mandibular left first premolar was extracted, and the mandibular arch was further aligned. When the patient was aged 15 years and 5 months, the tips of the bilateral maxillary canines, placed after the extraction of the right central incisor and the left lateral incisor, were trimmed. A resin restoration was performed for the right canine to mimic the crown shape of the right central incisor at the age of 16 years, 1 month.
Post treatment facial & intraoral photographs
Radiographs after the canine traction. (A) Panoromic radiographic (B) CBCT. 3-D reconstructed image(left) and the saggital slice image showing the maxillary right lateral incisor(right)
Post retention facial & intraoral photographs
What did the authors conclude?
The authors concluded that the total treatment duration was for about 48 months & a favourable occlusion with an overbite & overjet of 2mm was obtained. The crown of the transplanted tooth was reshaped to mimic the maxillary right lateral incisor. The mobility of the transplanted tooth was within the physiological range & the gingiva was healthy after active orthodontic therapy. There was a periodontal space present around the tooth and no signs of ankylosis were found. Slight root resorption was seen after the treatment & the color of the crown darkened slightly during retention. The third molars were planned to be extracted later.
Post treatment lateral cephalogram, Cephalometric tracing & Panaromic radiograph.
What do we think about it?
The autotransplantation of teeth offers a unique treatment option, especially when this is combined with orthodontic treatment. Many orthodontic patients need anterior or posterior teeth to be extracted. And in few cases, to replace a missing tooth, a natural tooth is always a better choice rather than a dental implant or bridgework. The advantage of tooth transplantation, unlike dental implants, is that the transplanted teeth have living periodontal ligaments. Thus, the sense of mastication and occlusion can be perceived, and orthodontic tooth movement can be performed. However, ankylosis, root resorption, and pulp necrosis are the most common complications. The key point for successful tooth transplantation to avoid complications is atraumatic preservation of the periodontal ligament of the donor tooth. In addition, the recipient alveolar socket must be slightly larger and deeper than the donor tooth root for a satisfactory prognosis. In patients whose posterior tooth is to be transplanted into the socket of an extracted anterior tooth, rotation of the tooth is an effective approach. All these precise plans and preparation must be considered and arranged before and during transplantation, which was meticulously carried out in this case. Although slight amount of resorption & discoloration of tooth was present towards the end of the treatment, it can still be said that this option is a novel method for correction of malocclusions in complicated cases, especially those in which extractions of multiple teeth might be required.
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