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Immediate autotransplantation of mandibular third molar in

China

Quanmei Yan, PhDa, Bo Li, PhDa, Xing Long, PhDb Wuhan, China

KEY LABORATORY OF ORAL BIOMEDICAL ENGINEERING OF MINISTRY OF EDUCATION, SCHOOL ANDHOSPITAL OF STOMATOLOGY, WUHAN UNIVERSITY

Objective. Tooth autotransplantation is a useful surgical method to replace a nonrestorable tooth. We reported ourexperiences in the replacement of mandibular nonrestorable molars by immediate autotransplantation in a Chinesepopulation.Study design. Thirty-five mandibular third molars with open or closed apices from 34 patients were autotransplantedinto the same or contralateral fresh recipient sites immediately after the extraction of the nonrestorable mandibularmolars. Root canal treatment was routinely performed in the closed-apical molars within 1 month after surgery.Clinical and radiographic examination of the transplanted donor molars was done after surgery.Results. Two teeth were been extracted for progressive root resorption. The remaining 33 autotransplanted teeth wereasymptomatic and functioning after a mean follow-up period of 5.2 years. No infection, ankylosis, loss of thetransplants, or root resorption was noted in the remaining autotransplanted teeth.

Conclusion. Immediate autotransplantation of the mandibular third molar is a reasonable and alternative treatment toreplace a nonrestorable tooth in China. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2010;110:436-440)

Although the Chinese have experienced economic

growth in the past 30 years, dental hygiene needs to be

improved,1 because the rate of tooth loss is high.2

Because the early loss of a permanent first molar may

have a long-term effect on occlusion, replacement of

the nonrestorable tooth may be beneficial. Dental im-

plants are a promising method for the replacement of

nonrestorable teeth. Given the high cost of dental im-plants, however, autotransplantation of a third molar is

sometimes a suitable alternative treatment for the re-

placement of the nonrestorable tooth, especially in a

developing country such as China. Tooth autotrans-

plantation is a useful surgical method to replace the

nonrestorable tooth, and its long-term survival rate is

high.3 Furthermore, tooth autotransplantation can be

performed immediately after the extraction of the non-

retainable tooth. In this case, the recipient site can

easily be adjusted to the donor tooth,4 and wound

healing and function retrieval of the autotransplanted

tooth is more rapid compared with dental implant.5

Unfortunately, tooth autotransplantation has not been

considered to be a viable treatment option in China,

even when an impacted third molar is found in a pa-

tient, because there are so few studies about tooth

autotransplantation. Therefore, we performed immedi-

ate mandibular third molar autotransplantation to re-

place the nonrestorable mandibular molar and summa-

rized our experiences in tooth autotransplantation.

PATIENTS AND METHODSThe study was composed of 34 patients in whom a

total of 35 mandibular third molars were autotrans-

planted. The average age of the 28 female and 6 male

patients at the time of transplantation was 24 years

(range 16-39 y), and the average follow-up period for

all teeth was 5.2 years (range 1-11 y).

Thirty-five mandibular third molars were trans-

planted into the same or contralateral fresh recipient

sites immediately after the extraction of the nonrestor-

able molars. The development stage of autotransplantedmolars was 5 or 6.6 There were 16 open-apical and 19

closed-apical donor molars for autotransplantation. Ra-

diography was used to determine the adaptability be-

tween the donor molars and the recipient sites.

The surgical procedure was the same as Tsukiboshis

method5 with little modification. The procedure is de-

scribed briefly as follows. After the extraction of the

nonrestorable tooth, the recipient site was prepared

based on the size of the donor tooth with a surgical

round bur at a low speed. Then the donor molar was

autotransplanted into the recipient site after the atrau-

aSenior Lecture, Department of Oral and Maxillofacial Surgery, Key

Laboratory of Oral Biomedical Engineering of Ministry of Education,

School and Hospital of Stomatology, Wuhan University.bProfessor, Department of Oral and Maxillofacial Surgery, Key Lab-

oratory of Oral Biomedical Engineering of Ministry of Education,

School and Hospital of Stomatology, Wuhan University.

Received for publication Nov 26, 2009; returned for revision Feb 3,

2010; accepted for publication Feb 9, 2010.

1079-2104/$ - see front matter

2010 Mosby, Inc. All rights reserved.

doi:10.1016/j.tripleo.2010.02.026

436


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matic extraction. The gingival flap was closed tightly

around the donor molar (Fig. 1).Wire fixation was used

only when initial stability were not achieved (Fig. 2).

Then the occlusal adjusting was performed if needed.

All patients were given oral antibiotics, instructions

about oral hygiene, and a soft diet during the first

postoperative week.

The suture and wire (if used) were removed after 1

week. Root canal treatment was routinely performed in

closed-apical molars and in open-apical molars if in-

flammatory resorption was detected by radiography.Patients were followed-up at 2 weeks, 1 month, 3

months, 6 months, and yearly thereafter.

Success was judged by the following criteria7: The

tooth was fixed in its socket without discomfort; chew-

ing was satisfactory; no pathologic condition was seen

on the radiograph, and the lamina dura appeared to be

normal on the radiograph.

RESULTSA total of 35 molars were autotransplanted during the

11-year period. The results of donor molars are sum-

marized in Table I. Two closed-apical donor molarswere extracted for progressive root absorption, and the

remaining donor molars were fixed in the socket with-

out discomfort and with satisfactory chewing. Two

open-apical donor molars were diagnosed with pulp

infection and were successfully treated endodontically.

Intact lamina dura appeared in all open-apical donor

molars on the radiograph. The apex closure was found

in open-apical donor molars (Fig. 3). Eight closed-

apical donor molars which missed routine root canal

treatment were diagnosed with pulp infection. In this

instance, calcium hydroxide (Ca(OH)2) dressing was

used and when symptoms disappeared the root canals

were obturated with gutta-percha and sealer. Intact lam-

ina dura appeared in 6 of these molars (Fig. 4), and 2

molars were extracted for progressive root absorption.

DISCUSSIONThe primary purpose of tooth autotransplantation is

to recreate a functional tooth. Although immediate

Fig. 1. Representative surgical procedure of autotransplantation. A,A 20-year-old woman has a nonrestorable left first mandibular

molar. B, The recipient site after the extraction of the nonrestorable tooth. C, After the donor tooth was placed in position, the

gingival flap was sutured tightly around the donor tooth without additional fixation.

Fig. 2. The donor tooth was fixed with wire across the

occlusal surface if the initial fixation was not achieved after

the autotransplantation.

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mandibular third molar autotranplantation can be easily

performed without additional bone surgery, the prog-

nosis is not assured.8 Several factors, such as careful

manipulation of the root and socket, stabilization of the

implanted tooth, and postoperative care, are important

to improve prognosis of this treatment.

Prognosis of the autotransplanted teeth was facili-

tated by histology, with healing including pulpal heal-

ing and periodontal healing. It has been shown that by

the 30th day after the autotransplantation of teeth, new

tissue consisting of well organized and well vascular-ized connective tissue could grow into the teeth9 and

that sufficient vascular supply could secure the survival

of pulp cells.10 However, this applied only with open-

apical teeth.11 The revascularization of closed-apical

teeth is usually not expected. Pulp necrosis happens

more often in closed-apical teeth and leads to inflam-

matory root resorption.12 Furthermore, open-apical do-

nor teeth have a better survival rate than closed-apical

donor teeth.13 Therefore, the treatment strategies for

open-apical and closed-apical teeth should be different.

For example, Tsukiboshi5 suggested that in developing

teeth, regular radiographic examination should be usedto find inflammatory resorption and that root canal

treatment should be initiated if any signs of pulp infec-

tion were observed. Whereas in fully developed teeth,

root canal treatment should be completed before sur-

gery or started 2 weeks after surgery. In the present

study, pulp infection happened in 2 open-apical donor

molars within 3 months after surgery, and these teeth

were treated with root canal treatment and achieved

good prognosis. On the other hand, in this study, the

closed-apical donor molars were routinely treated with

root canal treatment within 1 month after surgery. Root

canal treatment during the surgical procedure is notadvised, because it increases the risk of root resorp-

tion.14-15 In the present study, pulp infection happened

in 8 teeth which missed routine root canal treatment.

These infected teeth were difficult to be treated and

Ca(OH)2

dressing was chosen to ease the symptoms of

pulp infection.15 However, it takes a relatively long

time for Ca(OH)2

dressing to ease the symptoms, and in

some cases the root absorption is progressive. In this

study, 2 molars dressed with Ca(OH)2

were extracted

for progressive root resorption.

Periodontal healing usually completes after 8 weeks

and continuous space around the root appears radio-graphically, with absence of root resorption and pres-

ence of a intact lamina dura.14 Ankylosis strongly cor-

relates with damage to the root surface during the

operation, and the presence of an intact and viable

periodontal ligament on the root surface is one of the

most important factors in assuring healing without an-

kylosis.16 For example, ankylosis occurs in teeth with

cementum injury, suggesting that cementum is impor-

tant for the regeneration of the periodontal ligament.17

Therefore, preservation of the periodontal ligament of

the autotransplanted tooth is a key step to avoid anky-

Table I. Summary of the autotransplanted molars

Open apex

(n 16)

Closed apex

(n 19)

Root canal treatment 2 19*

Without fixation 5 6

Failure 0 2

*Eight molars missed scheduled root canal treatment.These 2 molars belonged to the 8 molars* that missed scheduled

root canal treatment.

Fig. 3. Radiography showing apex closed in a representativecase with open apex after autotransplantation. A, Intact lam-

ina dura appeared and apex was open at 9-month radiographic

follow-up.B,The apex was closed without apical infection at

3-year radiographic follow-up.

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438 Yan et al. October 2010


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losis. The length of the extra-alveolar period seems toexert some influence on the periodontal ligament, en-

hancing the development of ankylosis.16 Commonly,

the donor tooth is planted into the recipient site imme-

diately or placed in its original socket before it is

planted into the recipient site.5 In the present study, the

periodontal ligaments were preserved by the atraumatic

extraction of the donor molars. As mentioned above,

we routinely performed root canal treatment after sur-

gery in closed-apical molars to reduce the extra-alveo-

lar period and the chance of damaging the periodontal

ligaments.

Tight closure of the gingival flap around the donortooth is another critical step. Tsukiboshi5 suggested that

this procedure would secure the reattachment of peri-

odontal ligament and might block bacterial invasion into

the blood clot between the donor tooth and the socket. He

also suggested that this procedure could be performed

before the donor tooth is positioned into the recipient site.

We sutured the gingival flap after the donor tooth was

positioned into the recipient site, because it is easy to

suture the gingival flap around the donor tooth. Further-

more, if the socket needs further adjusting and the donor

molar has to be taken out, it may damage the periodontal

Fig. 4. Representative closed-apical case that missed scheduled root canal treatment. A, A 26-year-old woman with a nonre-

storable molar in the right mandible. The right third mandibular molar was intended to replace the nonrestorable tooth. B,

Radiography immediately after the autotransplantation of the donor tooth. C, The apical infection was found 4 months after

autotransplantation.D,After dressing with calcium hydroxide, the autotransplanted tooth was treated with root canal treatment (6

months after autotransplantation).E, No apical infection was found, and intact lamina dura appeared around the autotransplanted

tooth 3 years after autotransplantation.

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ligaments and extend the extra-alveolar period of the

donor molar.

The initial stability affects the prognosis, because

sufficient initial stability can avoid dislocation of the

autotransplanted teeth.5 Fixation with splint18 and su-

tures has been used to stabilize the autotransplanted

teeth. However, studies increasingly show that rigidsplint has a negative effect on the prognosis of the

donor teeth. For example, an experimental study of

autotransplanted teeth in monkeys showed that splint-

ing exerted a harmful effect on pulpal and periodontal

healing.19 A clinical study of 76 autotransplanted im-

mature third molars showed a significant increase in

ankylosis and pulp necrosis after rigid fixation for 4

weeks compared with suture splinting for 1 week.18

Indeed, prolonged rigid fixation of autotransplanted im-

mature third molars has a significantly negative influence

on final root length and root length increment,especially

in transplants at earlier developmental stages.20

Akkocao-glu and Kasaboglu7 suggested that frictional stabiliza-

tion with the adjacent teeth should be secure without

any fixation method and there should be good adapta-

tion of the root with recipient bone if the mesiodistal

dimension of the tooth being transplanted is similar to

that of the recipient area. In our experience, it is gen-

erally not difficult to get the stable autotransplanted

teeth if the size of donor tooth and recipient are con-

gruous. However, because of the variability of the third

molar, initial stability is difficult to achieve without

additional fixation in some patients, even when the root

development completed or the length of the root isenough. In this situation, the fixation is crucial and we

used a flexible wire to stabilize the donor molars and

removed the wires after 1 week after surgery. We

believe that ease and short term are the rules for fixation

of the autotransplanted tooth.

Altogether, our results showed that immediate auto-

transplantation of the mandibular third molar is a rea-

sonable and alternative treatment to replace a nonre-

storable tooth in China.

The authors thank Dr. Wei Fang for proofreading and

editing this manuscript.

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Reprint requests:

Professor Xing Long

Department of Oral and Maxillofacial Surgery

School and Hospital of Stomatology

Wuhan University

Wuhan, Hubei Province, 430079

China

[email protected]

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440 Yan et al. October 2010
mailto:[email protected]:[email protected]

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