Autotransplanted premolars with incomplete root formation in a growing patient with multiple missing teeth

A boy aged 8 years 11-months with 4 missing teeth in his mandibular arch and with a skeletal Class II pattern was treated with autotransplantation of developing premolars from his maxillary arch with the aid of temporary skeletal anchorage devices. The active treatment duration was 25 months. After treatment, he had a normal occlusion, and his profile was improved. Posttreatment records at 12 months showed stable occlusion and successfully autotransplanted premolars.

Highlights

  • A growing patient with Class II malocclusion had 4 missing mandibular teeth.

  • Two teeth from the maxillary arch were autotransplanted.

  • Autotransplantation allows normal vertical growth of the alveolar bone during the growth period.

Autotransplantation is the surgical movement of embedded or erupted teeth in the same patient from one site to another into extraction sites or surgically prepared sockets. The protocol for this technique was established in the 1970s, and has been developed over time. Long-term follow-up studies have supported that autotransplanted teeth resulted in stable success and good survival rates. ,

Mandibular second premolars are reported to be the most commonly missing teeth. Treatment of growing Class II patients with congenitally missing mandibular premolars is challenging. Orthodontic space closure may result in unwanted retraction of mandibular incisors, which makes it difficult to establish normal overjet and overbite. If orthodontic extraction is favorable in the maxillary arch, autotransplantation can be a viable treatment option. The transplant functions like a natural tooth because it has a periodontal ligament on the surface of the root, facilitating the physiological movement of the transplant. Because this feature allows orthodontic movement, the transplant is superior to dental implants, especially in young adolescents, because it accompanies normal vertical growth of the alveolar bone during the growth period.

This case report describes the orthodontic treatment of a growing patient who had multiple missing teeth in his mandibular arch. His maxillary first premolars were autotransplanted to his mandibular edentulous second premolar regions.

Diagnosis and etiology

The boy aged 8 years 11 months was referred for unerupted mandibular anterior teeth by his parents. He and his parents did not mention any history related to trauma. He was healthy, with no specific medical problems. In a temporomandibular joint evaluation, he did not show muscle or joint pain or other symptoms associated with temporomandibular dysfunction. The pretreatment facial photographs showed good facial symmetry and a convex profile. A clinical oral examination showed that he was in the early mixed dentition stage. His maxillary incisors were erupting with missing mandibular central incisors. Maxillary dental midline coincided with his facial midline ( Fig 1 ). The model analysis showed a 5.3-mm overjet, 3.1 mm overbite with end-on Class II molar relationship on the right side and Class I molar relationship on the left side. No crossbite was observed ( Fig 2 ).

Fig 1
Pretreatment facial and intraoral photographs (age, 8 years, 11 months).

Fig 2
Pretreatment dental casts.

A panoramic radiograph revealed 4 missing teeth in his mandibular arch, including his mandibular central incisors and mandibular second premolars. There were no missing teeth in his maxillary arch, but no third molar development was observed. Lateral cephalometric analysis showed that the patient had a Class II skeletal pattern with normovergent growth pattern (ANB, 5.2°; Mp-SN, 32.5°). His maxillary and mandibular incisors were proclined (SN-U1, 111.3°; IMPA, 103.2) ( Fig 3 ; Table ).

Fig 3
Pretreatment radiographs. A, Panoramic radiograph; B, Lateral cephalogram.

Table
Cephalometric measurements
Measurement Norm Pretreatment Posttreatment 1 y-retention
SNA (°) 82.0 84.0 81.8 81.9
SNB (°) 80.0 78.8 78.7 79.2
ANB (°) 2.0 5.2 3.0 2.7
Wits (mm) −1.0 −2.0 −0.9 −1.6
Mp-SN (°) 32.0 32.5 31.8 31.8
FH-MP (°) 25.0 26.6 26.0 26.0
LFH (ANS-Me/N-Me) (%) 55.0 54.3 54.6 54.9
SN-U1 (°) 104.0 111.3 101.0 103.3
U1-NA (°) 22.0 27.4 19.2 20.9
IMPA (°) 90.0 103.2 90.9 91.5
L1-NB (°) 25.0 34.6 21.5 22.5
U1/L1 (°) 124.0 112.9 136.2 133.4
Upper lip (mm) 1.2 0.1 0.2 0.3
Lower lip (mm) 2.0 4.6 −0.1 0.9

Treatment objectives

The treatment objective was to achieve Class I molar occlusion with normal overjet and overbite. Considering his convex profile and large overjet due to multiple missing teeth in his mandibular arch, one of the possible treatment options was to autotransplant his maxillary first premolars to the mandibular second premolar region while extracting retained deciduous mandibular second molars and to retract the maxillary anterior teeth to close the extraction space. The operation time was delayed until his maxillary first premolars emerged into the oral cavity, and the third quarters of the roots were formed. Because of the absence of both mandibular central incisors, it was necessary to substitute canines for lateral incisors. Mandibular first premolars would replace canines consequentially. Because of the mandibular canine substitution, ideal overbite and overjet might be compromised, so this was explained to the parents and patient.

Treatment alternatives

The main key to treat this patient was managing the excess space in his mandibular arch, which could not be closed with just conventional orthodontic treatment. A possible treatment option other than autotransplantation might be to keep his deciduous second molars until they exfoliate. Retaining healthy deciduous mandibular second molars can be a viable treatment option for patients with agenesis of their permanent premolars. Nevertheless, in the case of root resorption or ankylosis of deciduous teeth, dental implants or dental bridges could also be considered as a treatment option. As reported in some previous studies, , when dental implants are placed in growing adolescents, they can interfere with vertical alveolar development. Space maintainers such as a removable plate with pontics or temporary resin-bonded bridges could be considered if the deciduous teeth fall out before the patient has completed his growth. It is not easy to retain such space for a long time, but it is even more difficult to maintain the volume of the edentulous ridge. Without the eruption of the permanent teeth, the osseous ridge does not fully develop. As time goes by, the alveolar ridge will become narrower and more difficult to restore. An interdisciplinary approach may be required to develop the restoration site. The mandibular first premolars should be allowed to erupt after extraction of the deciduous first molars, and orthodontically moved to the second premolar region while maintaining the increased buccolingual alveolar width of the first premolar region. Then, dental implants can be installed in the first premolar region to prevent the need for a bone graft. The site developed by this orthodontic tooth movement will remain stable over time.

If the patient and parents are unwilling to accept any prosthetic restoration or space maintainer, another option would be mandibular molar protraction to the missing second premolar region with the extraction of the maxillary premolars. Although molar protraction has been traditionally considered difficult to perform, the development of temporary skeletal anchorage devices (TSADs) makes it a viable alternative treatment option in this case. From a preliminary study published in 2001 , recent studies show the possibility of molar protraction as a treatment solution. Longer treatment duration is unavoidable because the treatment can only be completed after the finishing of the terminal teeth. In our case, all treatment options were explained and discussed.

Treatment progress

The autotransplantation option was accepted. The patient was recalled every 6 months to evaluate the eruption of his maxillary first premolars and root formations. Panoramic radiographs and progressive records were taken. Before autotransplantation, his mandibular lateral incisors were moved mesially with a removable orthodontic appliance so that the mandibular canines would erupt more mesially ( Fig 4 ).

Jan 9, 2021 | Posted by in Orthodontics | Comments Off on Autotransplanted premolars with incomplete root formation in a growing patient with multiple missing teeth
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