ABSTRACT
This study describes the management of a case of multiple missing teeth involving premolar autotransplantation, othodontic treatment, and a 6-year follow-up of autotransplantation. The prognosis of the transplant was good with a satisfactory crown-root ratio. Autotransplantation is a viable treatment option that eliminates the need for prosthetic therapy or implants for children with missing permanent teeth.
INTRODUCTION
Treatment for children with several congenitally missing teeth is challenging because the growth and development of the oral structures have to be taken into account. One of the treatment options is the use of implants. However, because of the residual facial growth in young patients, infraocclusion of the implant may occur as the implant becomes ankylosed to the alveoler bone. The other treatment options include maintaining the deciduous teeth, extracting the deciduous teeth and allowing the space to close spontaneously, prosthetic replacement, and orthodontic space closure.1 On the other hand, if donor teeth are available, autotransplantation is a viable option. If the autotransplanted teeth do not ankylose, they will promote alveolar growth along with the eruption process.2 Autotransplantation involves the transfer of embedded, impacted, or erupted teeth from one site to another in the same individual into extraction sites or surgically prepared sockets.3 Successful tooth transplantation offers improved esthetics, arch form, dentofacial development, mastication, speech, and arch integrity.4
The treatment plan for missing teeth cases should be based on a comprehensive evaluation of the age, occlusion, and space requirements of the patient as well as the size and shape of the adjacent teeth.5 Premolars from one site (eg, a crowded arch) can be transplanted to another site to replace congenitally absent premolars.
This case report presents the management of a patient in the early mixed dentition with multiple missing teeth. It involves upper second premolar auotransplantation to the lower second premolar region, orthodontic treatment, and a 6-year follow-up of the autotransplantation.
CASE REPORT
The patient was an 8-year-old girl with an unremarkable medical history. No signs or symptoms of temporomandibular disorder were reported. Pretreatment records showed that the patient had normal vertical facial proportions and good facial symmetry. Her profile was mildly convex. On clinical examination, the girl was found to be in the early mixed dentition. Analysis of the study models disclosed a flush terminal plane of the molars on both sides. The overjet was 3.5 mm and the overbite was 3 mm. No crossbites were noted. The maxillary midline was deviated 4 mm to the right, but the mandibular midline was indeterminable owing to a diastema (Figure 1).
The pretreatment panoramic radiograph showed agenesis of the maxillary right second premolar, mandibular left and right central incisors, and mandibular right second premolar (FDI 15, 31, 41, 45) (Figure 2).
Treatment Plan
When the patient was referred to our clinic, she was in the early mixed dentition. Guidance of eruption was planned, and deciduous teeth 53 and 73 were extracted. The diastema between the lower central incisors was partially closed, and 33 and 12 erupted 8 months later. At this point we decided to extract 74. Based on the panoramic film taken 4 months later, we observed that impacted teeth 13 and 14 were transposed. Therefore, we extracted 54 and 55, and 13 and 14 erupted 15 months later.
The patient had one missing tooth on each of the upper right and lower left quadrants. She had two missing teeth in the lower right quadrant, but no missing teeth in the upper left quadrant. To obtain a functional occlusion, balance the missing teeth in each quadrant, and solve 4 mm of arch discrepancy and upper midline deviation, we decided to transplant the upper left second premolar to the lower right second premolar region. If we had chosen the alternative of extracting the lower deciduous second molar and closing the space, it would have resulted in a Class III molar relationship on the right side. For the other treatment options (implant or prosthetic replacement) the patient would have had to wait until completion of her growth and development. All the treatment alternatives were explained to the patient and her parents. They accepted the autotransplantation treatment option. If autotransplantation was not successful, an implant could be placed in the future. The patient had a Class II molar relationship on both sides with 3.5 mm of overjet and 3 mm of overbite, and the maxillary midline was still deviated 4 mm to the right before autotransplantation (Figure 3). Nearly half the root of the donor upper left second premolar was developed at the time of transplantation (Figures 4, 5).
Intraoral and extraoral photographs of patient before autotransplantation.
Periapical radiograph of impacted donor tooth (25) before autotransplantation.
A panoramic film was taken with a metal ball in place to estimate the amount of magnification before the transplantation. The proper size of the recepient site was calculated when adjusted for magnification. Transplantation was carried out when the patient was 11 years old: tooth 85 was removed under local anesthesia and the socket was fully prepared, with care being taken to preserve the buccal and lingual alveolar bone during extraction. The intra-alveolar septum was trimmed with a chisel and the socket was irrigated.
Then tooth 65 was extracted and, after minimal elevation of mucoperiosteal flap, the donor impacted tooth 25 was removed carefully, keeping the root and remaining periodontal ligament intact and untouched. The proper length and width was prepared for the donor tooth, which was then transplanted with nearly 90 degrees rotation. The transplant was immobilized using black silk sutures, composite adhesive and a stainless steel wire which was passed in a figure-of-eight configuration around the adjacent teeth (Figure 6). Occlusal adjustment of the implanted tooth was done to eliminate the possibility of premature contacts. Chlorhexidine rinse and amoxicillin were prescribed for a week.
The patient was not allowed to chew on the transplant side during the first month of the post-op period. After this period, she could start chewing a soft diet for 1 month and gradually increase the chewing load to normal function within 3 months. The patient was inspected on the first postoperative day to ascertain if the transplant had retained its position. The stability and position of the transplant were inspected weekly. Sutures were removed 1 week posttransplantation. Composite adhesives were maintained for 30 days and the flexible stabilization wires for 9 months. She was reviewed at the third and the sixth month; 9 months after autotransplantation, active orthodontic treatment was initiated. Little growth of root was observed during this period, with the crown-to-root ratio nearly 1:1. A periodontal ligament space and lamina dura could be observed (Figure 7).
Treatment Progress and Results
The subject had full fixed therapy; the Class II molar relationship was corrected using a cervical headgear. Orthodontic treatment continued for 4 years because of poor cooperation and lack of oral hygiene. At the end of active orthodontic treatment, a Class I molar relationship with ideal overjet and overbite were achieved, upper and lower arches were well aligned, and the deviated midline was corrected (Figure 8). There was posterior rotation of the maxilla and vertical development of mandible, based on cephalometric superimpositions, which could be due to the use of the cervical headgear (Figure 9). Lateral cephalometric radiographs and a cephalometric analysis of the patient before and after orthodontic treatment are shown in Figures 10 and 11 and Table 1. At the end of active orthodontic treatment, radiographic examination revealed completed root growth with an intact lamina dura and a defined periodontal space with partial pulp obliteration in the transplanted tooth. The levels of the alveoler ridges were similar to those of the adjacent teeth; final crown-to-root ratio was greater than 1:1 (Figure 12).
Intraoral and extraoral photographs of patient after orthodontic treatment.
Cephalometric superimpositions of patient before and after full fixed orthodontic treatment.
Cephalometric superimpositions of patient before and after full fixed orthodontic treatment.
Cephalometric radiograph of patient before full fixed orthodontic treatment.
Cephalometric radiograph of patient after full fixed orthodontic treatment.
Periapical radiograph of transplanted tooth at the end of orthodontic treatment.
Periapical radiograph of transplanted tooth at the end of orthodontic treatment.
During the retention period, the patient was instructed to wear upper and lower Essix plates (Dentsply Raintree Essix, New Orleans, LA) for 6 months all day followed by night only for the subsequent 6 months. The patient was last examined at age 17.5, 6 years after the transplantation procedure. The response of the transplant to electric pulp testing was positive. The mobility of the teeth was normal and the sulcus depth was less than 3 mm. However, external root resorption at the level of the alveoler ridges and loss of lamina dura was observed (Figure 13), therefore the patient was given periodontal therapy and was instructed to be examined frequently.
Periapical radiograph of transplanted tooth 6 years after autotranspantation.
DISCUSSION
Autotransplantation of teeth has evolved as an accepted treatment in orthodontics.6 Tooth transplantation offers several benefits when compared with other methods such as implants. Most tooth transplantation procedures can be accomplished by a single surgery. After successful surgery, the transplanted tooth recovers its proprioceptive function and normal periodontal healing. Thus, the patient has a natural chewing feeling and natural biological response. Furthermore, the transplanted tooth can serve as a bridge abutment or orthodontic anchorage.7 The tooth transplant in growing children can offer the benefit of continued alveolar bone induction.8
High autotransplantation success rates have been reported in various long-term studies. Andreasen et al9 reported survival rates of 95% and 98% for premolars transplanted with incomplete and complete roots, respectively, for up to 13 years. The evaluation of transplants to the lower second premolar region showed a survival rate of 92% with immature roots, while teeth with mature roots had an 82% survival rate after 4 years.10
The factors that lead to successful autotransplantation have been extensively investigated. Although there are published variations for the surgical protocol, the necessity of an atraumatic technique and minimal handling of the transplant to preserve an intact periodontal ligament and Hertwig's root sheath are important considerations. Otherwise, root growth can be compromised, leading to ankylosis or root resorption and attachment loss.4,11 Minimizing the time the tooth is out of the mouth during transplantation is also required for a successful tooth transplant.4,7,11 Kim et al12 found no relationship between the extraoral time and either root resorption or ankylosis within the experimental time of 7.8 minutes. In our case, the donor tooth was handled by the crown, great care was taken to preserve an intact periodontal ligament and Hertwig's root sheath, and it was transplanted to the recepient area immediately after extraction.
In some situations, if there is insufficient buccolingual width to accommodate the transplant, there may be resorption of the alveolar ridge at the recipient area. In our case, the donor tooth was transplanted with nearly 90 degrees' rotation owing to the insufficient buccolingual width at the occlusal level of the neighboring teeth, yet the premature contacts were eliminated. Most authors suggest that transplanted teeth be placed in the alveolus at the same occlusal level as the donor site so that it will develop a longer root than if placed in a superficial, more occlusal position.4
Other factors that may influence the outcome include adequate immobilization of the transplanted tooth, which usually requires only a tight suture. It is clear that rigid, long-term fixation of transplanted teeth might have adverse effects on the periodontal and pulpal healing of the tooth.13,14 The immobilization period can vary from 2 weeks up to 2 months, according to the mobility of the transplant.15 In our study, the transplant was immobilized by black silk sutures for 7 days, composite adhesive for 4 weeks, and a flexible, figure-of-eight, stainless steel wire around the adjacent teeth for 9 months.
Orthodontic forces should not be applied to a transplanted tooth during the first 3 to 6 months and, when force is initiated, its amount and duration should be minimized. Andreasen9 describes a window of opportunity between 6 and 9 months after transplantation, while revascularization is at its maximum. According to Hamamoto et al,16 orthodontic treatment can be initiated just after regeneration of the periodontal space and confirmation of the presence of the lamina dura radiographically. In our case, active orthodontic treatment was initiated 9 months after autotransplantation.
Successful transplantation is achieved when a tooth undergoes neither inflammatory pulpal changes nor progressive root resorption but has normal periapical healing with continued root development to maintain tooth function.17 The root development of a transplanted tooth can continue unimpeded, but it can also become impaired or arrested, leading to an unfavorable crown-to-root ratio. Although greater success rates are achieved by using teeth with immature roots for autotransplantation, teeth in the early stages of root development show less posttransplant root growth than those with more mature roots but incompletely formed apices.9 Since there is a possibility of no additional root growth after transplantation, it has been suggested that the donor tooth have at least three-quarters of its roots formed and an apical opening of more than 1 mm at the time of autotransplantation.18 Kristerson17 reported that transplants with half to three-quarters root development had the best prognosis for successful autotransplantation. Northway19 stated that the preferred stage of root development is between one-third and three-fourths complete. Paulsen et al,20 in a long-term study of 118 autotransplanted premolars in stages 3 to 4 according to the analysis of Moorrees et al,21 found arrested root formation in 19%, no arrested root formation in 26%, and partially arrested root formation in 55% of the transplants. Andreasen et al9 also reported that the incidence of pulp necrosis and root resorption was greater in mature premolar transplants because of their closed apices. Transplantation of a fully formed root negates the potential for pulp regeneration, but adequate endodontic therapy will still ensure high survival rates.9 In our case, the donor tooth was transplanted when half the root was almost completed. Pulpal healing was achieved because the transplanted tooth was immature, it had a wide apical opening, and the crown-root ratio was more than1:1; therefore, no endodontic treatment was needed.
Successful periodontal healing, which is completed within 2 months in most cases,9 is marked by the absence of root resorption and the presence of a lamina dura. Preservation of the periodontium of the grafted tooth is key to a successful clinical outcome.7,11 The periodontium appears as a continuous space around the root on the radiograph.8,22 Conversely, replacement root resorption occurs in teeth with cemental injuries, suggesting that cementum is important for regeneration of the periodontal ligament.22 Ankylosis is diagnosed within the first year by radiographic appearance (loss of lamina dura) and, according to Thomas et al4, a “high metallic percussive sound.”4
In our case, 9 months after autotransplantation, a lamina dura, periodontal ligament, and partial pulpal obliteration were observed; crown-root ratio was nearly 1:1. Partial pulp obliteration is common in transplanted teeth showing pulpal healing.6,9,23 At the end of active orthodontic treatment, the crown-root ratio was more than 1:1 and the prognosis of the transplant was good. However, 6 years after autotransplantation, surface resorption and a loss in the level of the alveolar ridges were observed. This resorption in the long term could be due to unfavorable oral hygiene because Andreasen et al9 reported that surface resorption is usually located in the cervical part of the root and diagnosed within the first year after transplantation. Oral hygiene is very important to the success of the transplanted teeth so the transplant should be followed for a long time.
CONCLUSIONS
Tooth autotransplantation is still a very useful method of replacing missing teeth if appropriate donor teeth are available. In growing individuals, the transplant not only maintains growth and development of the alveolar ridge, but also provides a permanent solution to the agenesis.