Autotransplantation inside vi e w of a de l i c a t e pr o c e d u r e You receive a call from a frantic mother informing you that her 10-year-old daughter has been in a bicycle accident; one of her upper front teeth has been knocked out; and the tooth cannot be located. You see Mom and daughter at your office shortly thereafter, calm them both down, confirm that there are no other dental injuries, and inform Mom of the options for replacing the lost tooth. One of those options might be one that is seldom used in the United States but is quite common in many Scandinavian countries. This is autotransplantation a technique in which the lost or extracted tooth is replaced with one of the patient s own teeth, which is later restored to the size, shape, and color of the missing tooth. This modality of treatment requires a team approach involving a periodontist or oral surgeon, an orthodontist, and a restorative dentist. Jim Janakievski, the interviewee for this issue of the Bulletin, is not an orthodontist but an experienced periodontist who has mastered the skills required to accomplish this somewhat delicate procedure and describes for us in detail how it is done. Dr. Terry McDonald Interviews Dr. Jim JanakievskI Terry McDonald (TM): What is tooth autotransplantation? Jim Janakievski (JJ): The term auto means within the same patient, so tooth autotransplantation is a surgical procedure where a tooth is extracted from one site and replanted to another site, or repositioned within the same socket, on the same patient. It can be considered in cases of displaced or impacted teeth and unilateral agenesis of premolars. Autotransplantation can also be utilized for tooth replacement of traumatized maxillary incisors. TM: Is there any research that has evaluated the long-term outcomes of tooth autotransplantation? JJ: There are many studies on tooth autotransplantation. It has been most extensively studied in Scandinavia. A recently published long-term review of cases had a follow-up range of 17 to 41 years. 1 The success rate was over 90%, which is similar to that of dental implant-supported restorations. TM: What factors should be considered when planning this type of treatment? JJ: The stage of root development of the transplant tooth is very important. Studies have evaluated the success of autotransplantation looking at both development of the periodontal attachment and pulpal survival. 2,3 Success rates are highest when the root development is two-thirds to full root length with an open apex. So timing is critical when planning this type of treatment. This stage of root development occurs between the Dr. McDonald Dr. Janakievski 19
ages of 9 and 12 years. Most traumatic injuries to anterior teeth seem to occur during this same period, making autotransplantation a good option for these patients (Figure 1). Figure 1 Panograph TM: Which tooth is most commonly selected for transplantation in a patient with an ankylosed or avulsed maxillary central incisor? JJ: In a child who has had trauma to the maxillary incisors with resultant ankylosis or loss of a tooth due to avulsion, we begin by selecting the tooth to be transplanted. Consideration is given to the stage of root development and the size of the crown. Measuring the contralateral incisor or the space available will assist in the selection. Usually we choose the mandibular first or second premolar. In most cases the second premolar is wider and may be more appropriate in mesiodistal dimension to replace a central incisor. TM: Is this treatment most applicable in patients who will require bicuspid extractions for orthodontic management? JJ: Of course this would be the ideal patient, but we can consider autotransplantation for nonextraction cases as well. The posterior space that results from the harvesting of the premolar can be closed by unilateral protraction of the posterior teeth, either with traditional or with mini-implant anchorage mechanics. This way, no future implant treatment to replace the bicuspid will be needed. TM: Can you describe the surgical procedure? JJ: The surgical treatment begins with the preparation of an osteotomy using burs, much like implant site preparation. The transplant tooth is then harvested and carefully transferred to the recipient site. It is usually secured in place with sutures or a wire splint. After initial stabilization, the tooth is monitored for root development and eruption (Figure 2). TM: When can an orthodontist apply force to the transplanted tooth? JJ: To answer this question, you must understand how a periodontal ligament heals. In the case of a traumatic avulsion and replantation, both the tooth and the socket are lined with periodontal ligament, and there is an intimate fit when the avulsed tooth is inserted into the socket. In such a case, the ligaments reattach, and this Figure 2a Transplantation of mandibular premolar Figure 2b Osteotomy preparation Figure 2c Transplantation of mandibular premolar 20 P C S O B u l l e t i n f a l l 2 0 1 0
Figure 3a 2 months Figure 3b 4 months Figure 3c 7 months Figure 2d Figure 3d Radiograph day 1 transplant Figure 3e RDUOGRAPH 7 MONTHS happens rapidly, usually within a few weeks. In the case of an autotransplanted tooth, the periodontal ligament is only on the harvested tooth root, and there is more space around it within the osteotomy site. Bone and periodontal ligament formation requires more time in this situation. Healing is monitored radiographically and is typically complete at about 3 to 4 months. At this time the transplant can be moved orthodontically, much like any other tooth (Figure 3). TM: When can the premolar be restored to look like a central incisor? JJ: Certainly the next phase of treatment will involve coordination between the orthodontist and the restorative dentist. Since the premolar is usually smaller than a central incisor, it must be very specifically positioned to allow for ideal restoration. For the incisogingival position, the orthodontist must use the cemento-enamel junction (CEJ) of the contralateral incisor as a guide. Positioning the transplanted tooth so that the CEJ is lined up with the adjacent central incisor minimizes the risk of developing uneven gingival margins as passive eruption occurs. In order to minimize future prosthetic tooth preparation, positioning must also take into consideration both the form of the transplanted tooth and the restorative procedure (bonding, veneer, crown) that will be used to normalize it. Since a central incisor has a straighter mesial contour and a more curved distal contour than a premolar, the tooth must be positioned with two-thirds of the residual space to the distal. To minimize the amount of enamel reduction that needs to be done on the facial, the transplant should be positioned slightly palatal on the ridge. Various restorative techniques or materials can then be utilized to change the morphology of this tooth (Figure 4). continued 21
Figure 4a before RESTORATION Figure 4b restoration WITH COMPOS- ITE VENEER TM: What is the advantage of using this technique for ectopic impactions? JJ: In the case of an impacted tooth, consideration should first be given to the techniques often used for surgical exposure and orthodontic eruption. However, we may be faced with a patient in whom the impacted tooth position would present a challenge for traditional orthodontic mechanics (Figure 5). For this patient, the central incisor was autotransplanted to a more natural orientation. With this approach, the orthodontic treatment was simplified and the overall treatment time reduced. Figure 5a Description TM: What are the risks of tooth autotransplantation? JJ: The risks include pulpal necrosis with development of inflammatory resorption and ankylosis or replacement resorption. Careful planning and meticulous treatment execution by the dental team can minimize these risks. Autotransplantation can simplify and reduce orthodontic treatment time for patients with impacted teeth. For patients with traumatized incisors, it can provide a functional and natural tooth replacement during their early growth phase and eliminate the need for a removable appliance. Indeed, tooth autotransplantation is another option, that we should consider when treatment planning our young patients. Figure 5b radiograph PRE-OP TM: Are there courses available in the United States, should our readers desire more information on this topic? JJ: There are no courses available at this time. I have been invited to present on this topic to several study clubs and academies. We are hoping to put together a course in the next Figure 5c exposure OF CENTRAL INCISOR 22 P C S O B u l l e t i n f a l l 2 0 1 0
2 years that would cover the surgical, orthodontic, and restorative aspects of autotransplantation. TM: What is the future of tooth autotransplantation? JJ: I view tooth autotransplantation as a precursor to what will be available in the near future. Research has been evaluating the process of biomineralization in tooth formation and its application to regenerative models in dentistry. 4 It has recently been demonstrated that a bioengineered scaffold shaped like a tooth can attract stem cells and grow a tooth in vivo. 5 Certainly s e a s o n e d the knowledge and skills developed by clinicians performing tooth autotransplantation will be of benefit when tooth regeneration becomes available to our patients. References 1. Czochrowska EM, Stenvik A, Bjercke B, Zachrisson BU. Outcome of tooth transplantation: survival and success rates 17-41 years posttreatment. Am J Orthod Dentofac Orthop. 2002;121(2):110-119. S 2. Andreasen JO, Paulsen HU, Yu Z, Ahlquist R, Bayer T, Schwartz O. A long-term study of 370 autotransplanted premolars, III:periodontal healing subsequent to transplantation. Eur J Orthod. 1990;12(1):25-37. Figure 5d 2 MONTHS 3. Andreasen JO, Paulsen HU, Yu Z, Bayer T, Schwartz O. A longterm study of 370 autotransplanted premolars, II:tooth survival and pulp healing subsequent to transplantation. Eur J Orthod. 1990;12(1):14-24. 4. Rauth RJ, Potter KS, Ngan AY, et al. Dental enamel: genes define biomechanics. J Calif Dent Assoc. 2009;37(12):863-868. 5. Kim K, Lee CH, Kim BK, Mao JJ. Anatomically shaped tooth and periodontal regeneration by cell homing. J Dent Res. 2010;89(8):842-847. Figure 5e 1 YESR Figure 5f day OF SURGERY AND 1 YEAR Jim Ja n a k i e v s k i, DDS, MSD received his DDS from the University of Toronto, 1995, and completed a general-practice residency, at St. Clare s Hospital, Schnectady, New York, in 1996. He completed his postgraduate training at the University of Washington, where he received a certificate in periodontology with an MSD degree and a fellowship in prosthodontics. He is a Diplomate of the American Board of Periodontology, serves as an affiliate assistant professor in the Department of Periodontology at the University of Washington, and maintains a private practice in Tacoma, Washington. 23