Material and methods

We recalled 56 patients who had undergone autotransplantation of 67 teeth at least 6 years earlier. All patients had orthodontic treatment with an edgewise appliance at the orthodontic department of Niigata University Medical and Dental Hospital and tooth autotransplantation with complete root formation at the oral surgery department of our hospital in Niigata, Japan, from 1993 to 2000. Teeth diagnosed with ankylosis before the operation and teeth preserved frozen were excluded ( Fig 1 ).

Observation periods of transplanted teeth. The vertical line indicates the tooth number. Each horizontal line shows 1 transplanted tooth during the observation period. The left and the right ends denote the time of surgery, and the last time of observation, respectively. Transplanted teeth that were extracted are marked with a star . Tooth 15 was extracted because of periodontal disease. Tooth 19 had inflammatory resorption. Teeth 11, 18, and 25 had replacement resorption. Lines 1-38 represent the subjects of this study. Lines 39-67 indicate patients not included in this study, but these transplants still survived at the patient’s last visit to our hospital.

The attendance rate was 57.1%, and the prognoses of 38 teeth in 32 patients were examined. Of those, 5 patients had already lost 1 transplanted tooth. In this study, therefore, 27 patients (17 women, 10 men) with 33 surviving autotransplanted teeth were examined. The mean age at the time of surgery was 24.1 years (female subjects, 25.8 years; range, 10.8-43.2 years; male subjects, 20.7 years; range, 14.0-33.7 years). The mean postoperative period was 9.2 years (range, 6.1-14.5 years) ( Fig 1 ). The donor teeth and recipient sites are shown in Table I .

For 31 teeth, transplantation was performed to compensate for agenesis, congenital missing teeth, or tooth absence due to decay and periodontitis. Two teeth were transplanted for surgical correction of transposition.

All transplantations were performed according to the procedure described by Andreasen et al. An important feature of this procedure includes the preservation of the periodontal membrane to the maximum extent, tight sutures, rests of transplanted teeth with sufficient clearance between opposite teeth, and so on. Root canal treatment and temporary root filling with calcium hydroxide of the transplanted teeth were done within 3 weeks after the operation. Postoperative fixation was carried out with composites, and wire splints were removed after 3 weeks.

The survival rate was calculated as the percentage of transplanted teeth that were still present at the examination relative to the total number of transplanted teeth. The success rate was represented as the percentage of transplanted teeth that showed no abnormal findings: no progressive root resorption, and normal hard and soft periodontal condition relative to the total number of transplanted teeth.

The assessments were conducted clinically by an author (Y.W.). The transplanted teeth were compared with the contralateral donor teeth as the control teeth. The radiographs were analyzed independently by 2 observers, an author and another dentist (T.M.). In case of disagreement, the observers discussed their observations to obtain consensus.

The plaque index (4 sites) was measured according to the method of Silness and Löe, and the gingival index (4 sites) was measured according to the method of Löe and Silness. The probing depth was recorded at 6 sites with a periodontal probe (CPITN-C, YDM, Tokyo, Japan).

Depending on the condition of restoration, the materials were categorized into the full-restoration group (FRG: crown or bridge) or the partial-restoration group (PRG: composite filling or inlay).

With radiography, replacement resorption (ankylosis) was defined as the disappearance of the periodontal space and root resorption without radiolucency in relation to the resorpton area. Inflammatory resorption was defined as resorption cavities on the root surface associated with similar resorption activity in the adjacent alveolar bone. Furcation or periapical lesions were recorded as abnormal findings. The quality of root filling was considered to be suitable when the root filling material appeared to end 2 mm or less from the radiographic apex, without a visible apical lumen. Root filling was inadequate under all other circumstances.

The mobility of the teeth was assessed by using Periotest (Gulden-Medizintechnki, Bensheim, Germany). The measurements were made 3 times, and the average values were used, after confirming the absence of significant differences among premeasurements made 3 times. The Periotest values (PTV) were converted into numeric scales ranging from –8 to +50. The PTV was correlated with Millar’s index as follows: –8 to +9, no noticeable movement (0); 10 to 19, first distinguishable sign of mobility (1); 20 to 29, deviation of the crown to within 1 mm of its normal position (2); and 30 to 50, easily noticeable mobility (3).

Study models were prepared to determine the presence or the absence of occlusal contacts and to measure the level of gingival margins. The level of the gingival margin was measured as the distance between the most apical point of the soft-tissue margin at the facial aspect of the crown and a line connecting the midfacial level of the soft-tissue margin of 2 adjacent teeth. Transplanted teeth located in the most distal position in the dental arch were excluded. The measurement was conducted with digital calipers (ABS Digimatic Caliper CD-20C, Mitutoyo, Tokyo, Japan) on study models.

Orthodontic movement was checked from the orthodontic treatment records.

Results

The survival rate was 86.8%, because 5 teeth in 5 patients of the 38 teeth in 33 patients had been lost. Of those, 3 showed replacement resorption, 1 had inflammatory resorption, and 1 showed periodontal disease. The success rate was calculated to be 63.1%, since there were abnormal findings in 9 autotransplanted teeth including the 5 lost teeth, as mentioned above.

The plaque and gingival indexes tended to be higher in the transplanted teeth than in the control teeth. The transplanted teeth tended to show slightly increased pocket depths compared with the control teeth. On the status of restoration, 21 transplanted teeth were classified as FRG and 12 teeth as PRG. The results of the periodontal assessment were suspected to be influenced by the condition of restoration, because FRG accounted for about 60% of the materials between the 2 groups. The probing depth tended to be greater in the FRG group than that in the PRG group ( Table II ). In addition, the plaque and gingival indexes also tended to be higher in the FRG group than in the PRG group, but the difference was not significant.

No evidence of pathology was detected in 24 of the transplanted teeth ( Fig 2 , A ). Six showed replacement resorption ( Fig 2 , B ), 1 had inflammatory resorption ( Fig 2 , C ), and 2 showed a furcation-periapical lesion ( Fig 2 , D ). The quality of root filling was considered to be adequate for 23 transplanted teeth ( Fig 2 , E ). However, the remaining 10 were inadequate because the root filling in these subjects was not homogeneous, and there was a visible space ( Fig 2 , F ). In the 10 transplanted teeth with inadequate root filling, 3 showed replacement resorption, 1 showed inflammatory resorption, and 2 showed a furcation-periapical lesion. In addition, the root filling was inadequate in 4 of the 5 transplanted lost teeth.

Radiographs of typical subjects. A , 12 years 11 months after transplantation of a mandibular premolar to the maxillary molar region, the root filling is compact, and the periodontal ligament is good. B , 12 years 8 months after transplantation of a mandibular premolar to the maxillary premolar region, the root filling is compact, but the mesial periodontal space was lost, suggesting replacement resorption ( arrowheads ). C , 14 years 6 months after transplantation of the mandibular third molar to the opposite mandibular molar region, root filling was inadequate with a visible lumen ( arrow ). Resorption cavities were noted on the root surface associated with similar resorption activity in the adjacent alveolar bone, and inflammatory resorption was observed ( arrowheads ). D , 11 years 11 months after transplantation of the mandibular third molar to the opposite mandibular molar region, root filling appears to be poor ( arrows ), and a furcation-periapical lesion was observed ( arrowheads ). The probing depth in the central buccal region was 6 mm. E , Root filling is adequate; the root filling material appears to end 2 mm or less from the radiographic apex and without a visible apical lumen. F , Root filling is inadequate; the root filling material appears to end 2 mm from the radiographic apex and with a visible apical lumen ( arrow ). Periapical lesions were observed ( arrowheads ).

Tooth mobility (PTV) had a low tendency in the transplanted teeth compared with the control teeth, but the difference was not significant ( Fig 3 ). On the other hand, 6 of the transplanted teeth showed a negative PTV, which was considered to be attributable to the replacement resorption observed in the radiography ( Fig 2 , B ).

PTVs: ●, normal; Δ, furcation-periapical lesion; ◊, inflammatory resorption; ☆, replacement resorption.

Five teeth showed infraocclusion; 3 had replacement resorption, 1 showed inflammatory resorption, and another 1 had no sign of pathology in the maxillary anterior region.

There was no significant difference between the transplanted and the control teeth in the level of gingival margin ( Table III ).

Orthodontic movement was undertaken for 32 teeth after a mean postoperative period of 5 months. This proved to be impossible in the treatment records for 5 transplanted teeth; this was attributed to the replacement resorption found by radiograph.

The quality of root filling, PTV, occlusal contact, and course of orthodontic movement were significantly associated with the success of transplant ( Table IV ).

Table IV

Correlations among the independent variables

	Successful transplant	Sex	Age	Years after procedure	Plaque index	Gingival index	Probing depth ≥4 mm	Restoration	Root filling	PTV	Occlusal contact	Orthodontic movement
Successful transplant	1
Sex	−0.04	1
Age	0.13	−0.38 ∗	1
Years after procedure	−0.18	−0.15	−0.40 ∗	1
Plaque index	0.09	0.36 ∗	−0.31	0.06	1
Gingival index	0.02	0.15	−0.52 ∗	0.4 ∗	0.68 ∗	1
Probing depth ≥4 mm	0.18	0.18	−0.22	−0.22	−0.04	−0.14	1
Restoration	0.18	0.05	−0.10	−0.09	−0.02	−0.16	0.24	1
Root filling	0.69 ∗	0.11	0.05	−0.04	0.19	0.11	0.18	0.18	1
PTV	0.50 ∗	−0.08	0.20	−0.18	−0.07	−0.11	0.01	0.20	0.33	1
Occlusal contact	0.35 ∗	−0.30	0.13	−0.05	−0.15	−0.08	−0.09	−0.22	0.18	0.14	1
Orthodontic movement	0.51 ∗	−0.30	0.04	0.14	−0.15	0.06	0.09	0.08	0.18	0.35 ∗	0.27	1

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