When contemplating replantation and autotransplantation, the main focus for orthodontists is likely to be the advantages of autotransplantation, which has become an attractive treatment for replacing missing maxillary incisors. The focus of this article will be on a comparison between teeth replanted as autotransplants and those replanted after traumatic avulsion.
With replantation, long-term treatment decisions need not be made while managing an emergency….Replanting an avulsed tooth will allow interdisciplinary consultations and a definitive treatment plan.
Dentists tend to think that most replanted avulsed teeth have a poor long-term prognosis and create problematic restorative situations. These concerns are focused on the potential for a replanted tooth to become ankylosed. Replantation of an avulsed tooth, however, does not necessarily guarantee that the tooth will become ankylosed and give rise to a deficient alveolar ridge, nor does it preclude autotransplantation as a subsequent consideration.
When considering replantation vs autotransplantation of an avulsed tooth, the difference in published success rates appears to favor autotransplantation. Although success rates are important, they are not the sole consideration in the management of a missing anterior tooth. Reported success rates for autotransplanted teeth range from 21% to 100%. For autotransplanted premolars to the anterior region of the mouth, the success rate claims are 79% to 93%. The success rates for replanted teeth after traumatic avulsion are 9% to 50%. However, Andreasen and Andreasen and others have claimed success rates between 71% and 82% when avulsed teeth are replanted under more favorable conditions. The disparate success rates arise from the clinician’s ability to control important variables during autotransplantation vs no control of most circumstances after a traumatic avulsion. A surgeon has control of important variables such as extra-alveolar dry time and physiologic wetting solutions during autotransplantation, whereas a clinician commonly has no control over what happens to a tooth immediately after it is avulsed.
In ideal clinical management, primarily 2 tissues, the periodontal ligament and the pulp, are injured during autotransplantation. In contrast, the periodontal ligament, pulp, cementum, alveolar bone, and gingiva might all be damaged in the trauma involving an avulsed or a displaced tooth. The more structures that are injured, the more complicated and unpredictable the survival and return to function of these tissues becomes. From an endodontic perspective, however, most pulpal problems can be resolved with endodontic treatment in either autotransplantation or replantation of an avulsed tooth.
Potential for ankylosis
The main concern in the treatment of a growing child is the potential for ankylosis of a replanted tooth. Ankylosis is fusion of the alveolar bone and the root surface. It produces 2 clinical consequences—replacement resorption and arrested ridge development. Replacement resorption is the progressive resorption of the root of the tooth and its replacement by bone. If it occurs, this characteristic can be used to a clinical advantage. Arrested development of the alveolar ridge associated with an ankylosed tooth can result in a progressive vertical ridge defect as a child grows. Adequate augmentation of these large defects remains a difficult clinical challenge. These extensive ridge deformities have raised so many concerns that one consideration is that teeth with an extra-alveolar time greater than 5 minutes should not be replanted. But that approach comes with its own set of problems. These include long-term temporization for a growing child, progressive ridge resorption in the avulsion site that requires additional separate grafting procedures, and the need for additional orthodontic treatment.
Although there has been extensive research related to replantation of avulsed teeth, ankylosis remains the predominant clinical problem. Inquiries into the factors that affect replantation success have been published since the mid-1800s. Over time, research suggests that the most important variable in preventing ankylosis and replacement resorption is a viable periodontal ligament on the root of the tooth at the replantation. Periodontal ligament viability is primarily associated with how long a tooth is out of the socket and the effect of the physiologic storage medium during the extraoral time. Immediate replantation (less than 5 minutes) is best for the preservation of a viable periodontal ligament. In fact, viability of the periodontal ligament remains high with an extra-alveolar dry time up to 15 minutes.
Limiting the time the periodontal ligament is dry while a tooth is out of the socket might also decrease the incidence of ankylosis. Hank’s balanced salt solution (SAVE-A-TOOTH; Phoenix-Lazerus, Inc, Pottstown, Pa) is the preferred medium to preserve periodontal ligament viability. As a practical matter, however, cold milk and saliva are more likely to be immediately at hand. Cold milk can keep the periodontal ligament cells viable for about 6 hours, and saliva for 30 minutes. Although laboratory research has established time parameters for the efficacy of storage media in maintaining the viability of the periodontal ligament, correlation of such data with prevention of ankylosis is not yet available.
Advantages of replantation
Replantation of an avulsed tooth is a basic starting point even when the ideal conditions to prevent ankylosis cannot be met. With replantation, long-term treatment decisions need not be made while managing an emergency. To construct a complex treatment plan at the time of the tooth avulsion is an unreasonable expectation. Replanting an avulsed tooth will allow interdisciplinary consultations and a definitive treatment plan to ensue in a deliberate fashion. In addition, a replanted tooth can serve as an interim replacement. It can also act as a scaffold to prevent rapid loss of alveolar bone during remodeling of the socket. An alternative to replantation is to place a socket graft to preserve the alveolar ridge. This seems like a simple solution. Nevertheless, most accidents occur between the ages of 8 and 12 years. A socket graft must preserve the alveolar ridge until the child has stopped growing, often for a period of 5 to 10 years. In a series of patients followed for 3 to 7 years after traumatic tooth loss in the anterior maxilla, socket grafting failed in 82.4% of the sites to provide sufficient bone to support the placement of a dental implant without an additional bone graft.
If a replanted tooth becomes ankylosed, it does not preclude subsequent autotransplantation. Ankylosis can be clinically diagnosed as early as 2 months after replantation; most cases are found within 6 months to 1 year. If a tooth does become ankylosed and the child is a candidate for autotransplantation, the tooth can still be removed without missing the optimal time for transplantation success.
Finally and most importantly, when a decision is made to replant a tooth, it is crucial that the primary dentist, specialists, and parents all assume responsibility for monitoring the child’s dentition for signs of replacement resorption. Together, each will have a role in ensuring that any upcoming decision regarding autotransplantation or decoronation is made and performed at the appropriate time ( Fig ).
Advantages of replantation
Replantation of an avulsed tooth is a basic starting point even when the ideal conditions to prevent ankylosis cannot be met. With replantation, long-term treatment decisions need not be made while managing an emergency. To construct a complex treatment plan at the time of the tooth avulsion is an unreasonable expectation. Replanting an avulsed tooth will allow interdisciplinary consultations and a definitive treatment plan to ensue in a deliberate fashion. In addition, a replanted tooth can serve as an interim replacement. It can also act as a scaffold to prevent rapid loss of alveolar bone during remodeling of the socket. An alternative to replantation is to place a socket graft to preserve the alveolar ridge. This seems like a simple solution. Nevertheless, most accidents occur between the ages of 8 and 12 years. A socket graft must preserve the alveolar ridge until the child has stopped growing, often for a period of 5 to 10 years. In a series of patients followed for 3 to 7 years after traumatic tooth loss in the anterior maxilla, socket grafting failed in 82.4% of the sites to provide sufficient bone to support the placement of a dental implant without an additional bone graft.
If a replanted tooth becomes ankylosed, it does not preclude subsequent autotransplantation. Ankylosis can be clinically diagnosed as early as 2 months after replantation; most cases are found within 6 months to 1 year. If a tooth does become ankylosed and the child is a candidate for autotransplantation, the tooth can still be removed without missing the optimal time for transplantation success.
Finally and most importantly, when a decision is made to replant a tooth, it is crucial that the primary dentist, specialists, and parents all assume responsibility for monitoring the child’s dentition for signs of replacement resorption. Together, each will have a role in ensuring that any upcoming decision regarding autotransplantation or decoronation is made and performed at the appropriate time ( Fig ).
