Miguel Roig Cayón
Doctor en Medicina, Estomatólogo. Jefe de Área de Restauración Dental y Endodoncia
José Espona Roig
Odontólogo. Profesor Asociado, Máster en Estética Dental. Profesor Asociado. Área de Restauración Dental y Endodoncia.
Joan Grau Cases
Cirujano máxilo-facial. Odontólogo. Profesor Asociado. Área de Cirugía Oral e Implantología
Fernando Durán-Sindreu Terol
Doctor en Odontología. Máster en Endodoncia. Director del Máster en Endodoncia. Área de Restauración Dental y Endodoncia
Ankylosis of anterior teeth is a serious complication of replanted or severely traumatized permanent incisors. These processes might cause a severe damage to the periodontal ligament cells that cover the root surface. As a result of this damage, the periodontal ligament is replaced by bone tissue, causing ankylosis between tooth and bone1. Once ankylosis is established it will eventually continue until complete resorption of the root and replacement by bone, leading to tooth loss. Ankylosis and replacement resorption are largely responsible of the low 5-year survival of teeth after these injuries2-4. According to Andersson5 the rate of root resorption in the group of patients aged 8 to16 years was significantly higher compared with the group of patients aged 17 to 39 years.
Most of dental trauma conducing to avulsion, intrusion and lateral luxation occur to young individuals, being most common between 8 and 10 year old patients, during the early mixed dentition6,7. In a growing individual ankylosis will develop an infraposition of the damaged tooth. The alveolar development will be arrested and the future aesthetic and/or functional treatment will be severely compromised. Therefore, an ankylosed tooth in those conditions should be removed before future orthodontic and/or prosthodontic therapy is jeopardized8. This should be done as soon as infraposition in diagnosed.
Treatment options to be considered include: composite builp-up, bone distraction, segmental osteotomy, tooth extraction, decoronation and auto transplantation. Tooth extraction seems to be an inadequate treatment option for the undesirable lowering and diminishing of the horizontal and vertical volume that it always causes9-11, in this case increased by the probably bone loss related to the always difficult extraction of an ankylosed tooth. And implant placement in the area has to be necessarily postponed until complete growth of the patient has been accomplished. Correcting the defect with a composite build up might be a treatment option if the patient has passed the pubertal growth and there is minimal infraposition, but it would never be recommended for growing patients, for infraposition will be increased, and the patient will end with a very long tooth and big asymmetry in the gingival margins. Bone distraction by dento-osseus osteotomy of the segment would be a possibility12-14 but it should be postponed until complete growth of the patient. Segmental osteotomy with autogenous bone graft has also been proposed, but there is only one case presented15, as far as we could find. Therefore, only two options remain, decoronation of the ankylosed tooth and auto transplantation of the first premolar to the anterior region.
Decoronation is a simple and safe surgical method first described by Malmberg in 198416 for preservation of alveolar bone prior to implant placement. As soon as infraocclusion is detected, a flap is raised to gain good access. The crown is removed two millimetres below the cervical margin. An endodontic file or a bur are then used to remove any root filling material or pulp from the root canal, and to allow blood flow into root canal space. The flap is then reattached covering the width of the tooth. When decoronation is done before pubertal growth spurt a vertical bone growth might be expected, and the width of the alveolar ridge is maintained in patients of all ages8. It is probably the treatment of choice in most of ankylosed teeth in growing patients for it preserves alveolar dimension thus enabling implantation after the completion of growth and development.
An alternative to decoronation is tooth auto transplantation. Many of the patients suffering ankylosis in anterior teeth have malocclusion17, mainly Angle class II, and might need tooth extractions to correct their malocclusion. If the orthodontic study determines the need of lower premolar extractions, auto transplantation should be considered. Auto transplantation is a reliable treatment method. In a study Kvint et al. informed of an overall success rate of 81% over 215 patients18.
The highest success rate, a 100%, was for transplantation of premolars to the maxillary anterior region. According to Czochrowska et al.19 the overall status of the transplanted premolars and surrounding tissues, similar to natural incisors, indicated that this treatment modality may be recommended when maxillary incisors are missing in adolescents. In addition, tooth transplantation represents an inherent potential for bone induction and reestablishment of a normal alveolar process.