Material and methods

We retrospectively reviewed the records of all patients (89 total; 20 male, 69 female) who had autotransplantation of teeth with complete root formation (100 teeth) at our institution from 1995 to 2012. All patients received orthodontic treatment with an edgewise appliance at the Department of Orthodontic Science of Tokyo Medical and Dental University in Japan. The study was approved by the ethical committee of the Faculty of Dentistry of Tokyo Medical and Dental University (approval number: 1022).

Mean patient age at the time of autotransplantation was 29.1 years (males, 28.9 years; range, 18.7-50.8 years; females, 29.2 years; range, 12.3 [with completed root formation]-58.1 years) ( Table I ). The mean follow-up period was 5.8 years (range, 1.9-14.7 years). The donor teeth and the recipient sites are shown in Table II .

All transplantations were performed by experienced oral and maxillofacial surgeons according to the procedure described below ( Fig 1 ). To prevent excessive occlusal stimuli, the donor teeth were seated carefully into the socket without occlusal contact and splinted to adjacent teeth. Postoperative fixation was carried out with composites and cobalt-chromium wires. Two weeks after transplantation, endodontic treatment was performed with pulp extirpation and calcium hydroxide dressing, before root filling with gutta-percha and a sealer. Four to 8 weeks after transplantation, the splinting was removed, and alignment of the transplanted teeth began. Orthodontic treatment was carried out with 0.018 × 0.025-in slot preadjusted edgewise appliances; 0.016 × 0.022-in superelastic nickel-titanium alloy wires were used for the alignment.

Procedures during and after transplantation.

Each transplanted tooth was clinically and radiographically assessed by the same examiner (Z.K. or S.K.). As part of the standard protocol, the following baseline information was retrieved from the medical records and dental casts before transplantation: date of transplantation, donor tooth type, the presence of donor tooth occlusal contacts, and the cause of tooth loss, if applicable. We divided the recipient sites into 3 groups according to the reason for transplantation: prolonged retention of deciduous tooth, missing tooth (including congenitally missing teeth), and permanent tooth with a poor prognosis.

The criteria for “success” were adapted from the studies of Czochrowska et al and Kallu et al. We defined a “successfully transplanted tooth” as one that met the following criteria: (1) normal soft periodontal tissues; (2) no progressive root resorption; (3) no ankylosis (ankylosis was defined as absence of radiolucency between donor tooth root and alveolar bone, high metallic sound of percussion test, and no physiologic mobility); (4) physiologic mobility; (5) no apical infection; and (6) a crown-to-root ratio less than 1, necessary to maintain tooth function (root length greater than half of tooth length). Teeth not fulfilling all criteria were classified as “tentative.” Teeth that were lost or extracted were designated as failures. Tentative and successful teeth were classified as “surviving.”

The total “success rate” was the number of teeth that met the aforementioned conditions, relative to the total number of transplanted teeth. The “survival rate” was the percentage of transplanted teeth still present and functioning well at the time of examination.

Clinical examination included assessments of tooth mobility, palpation, color, inflammation, percussion, probing pocket depth, gingivitis index, and occlusal contacts, according to the method of Denys et al. Tooth mobility was scored on a scale from 0 to 3 (0, no mobility, ankylosis; 1, normal mobility; 2, horizontal mobility; and 3, tooth could be intruded). Pocket probing was performed with a calibrated periodontal probe (CPITN-C; YDM, Tokyo, Japan) at 6 sites on the transplanted tooth: mesiovestibular, vestibular, distovestibular, distolingual, lingual, and mesiolingual regions. Pocket depth exceeding 3 mm was considered pathologic. The sulcus bleeding index proposed by Mühlemann and Son was used to assess gingivitis.

On radiological evaluation, ankylosis was defined as the disappearance of the periodontal space and root resorption without radiolucency relative to the resorption area. Root resorption was defined as resorption cavities on the root surface associated with similar resorption activity in the adjacent alveolar bone. Furcation lesions and periapical lesions were recorded as abnormal findings.

Results

The survival rate of the 100 teeth transplanted in 89 patients was 93.0%; 7 teeth in 6 patients fell out. Of the 93 surviving teeth, 15 developed ankylosis, and 10 had root resorption (3 had both ankylosis and root resorption). The success rate was thus 71.0% because 29 autotransplanted teeth had abnormal findings, including the 7 that fell out ( Table III ). The cumulative survival rates when donor teeth had complete root formation were 96.4% at the 5-year mark and 89.5% at 10 years, as calculated with the Kaplan-Meier method ( Fig 2 ). According to donor tooth type, the survival and success rates were 75.0% (3 of 4) and 50.0% (2 of 4) for incisors, 94.4% (51 of 54) and 77.8% (42 of 54) for premolars, and 92.9% (39 of 42) and 64.3% (27 of 42) for molars at 5 and 10 years, respectively ( Table IV ). The donor teeth had occlusal contacts in 61 of the 93 surviving teeth.

Survival analysis of autotransplanted teeth according to the Kaplan-Meier method (truncated at 14 years after autotransplantation).

Table IV

Comparison of presurgical conditions and postsurgical outcomes

	n		Ankylosis		Resorption		Mobility		Pocket depth		Inflammation
	Surviving	Fell out	(+)	(−)	(+)	(−)	(+)	(−)	(+)	(−)	(+)	(−)
Donor tooth type
Incisors	3	1	0	3	1	2	0	3	0	3	0	3
Premolars	51	3	7	44	2	49	2	49	5	46	3	48
Molars	39	3	8	31	7	32	4	35	8	31	4	35
Donor tooth condition
Occlusal contact (+)	61	4	9	52	4	57	4	57	10	51	3	58
Occlusal contact (–)	32	3	6	26	6	26	2	30	3	29	4	28
Recipient teeth site
Incisors	15	2	1	14	1	14	0	15	1	14	0	15
Canines	1	0	0	1	0	1	0	1	0	1	0	1
Premolars	37	4	8	29	3	34	1	36	2	35	2	35
Molars	40	1	6	34	6	34	5	35	10	30	5	35
Recipient site condition
Prolonged retention of deciduous tooth	24	3	4	20	3	21	1	23	4	20	2	22
Missing tooth	49	0	10	39	3	46	1	48	5	44	3	46
Tooth with poor prognosis	20	4	1	19	4	16	4	16	4	16	2	18

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