Experimentally induced dentoalveolar ankylosis in rats

Dentoaiveoiar ankylosis is a common complication after replantation of teeth with injured periodontal ligaments. This is a serious complication for the tooth since it leads to progressive root resorption. In young individuals it may also cause infra-occlusion and reduced develop-ment of the alveolar process. The purpose of this study was to develop a method applicable to rats in order to follow the effect of systemic and local factors on the development of ankylosis and their possible effect on the length of the functional period of the ankylosed tooth before exfoliation. The maxillary first molars in adult rats were extracted. The periodontal ligaments were devitalized or removed before replantation of the teeth. Dentoalveolar ankylosis was clinically established 2 weeks after replantation. Induction was most reproducible after devitaiization or removal of the PDL cells with Dakin's solution and after keeping the rats on a liquid diet up to 3 weeks after replantation. Exfoliation of the teeth usually occurred 6 weeks after replantation. Histological examination showed that the PDL was replaced by bone. The ankylosed teeth showed root resorption to a varying degree. The resorption was in some cases occasionally located in the supra-crestal part of the tooth. A bone-like tissue in the root canal was a rather common finding. In one of the ankylosed teeth cartilage formation was found adjacent to the cementum.     

Decoronation – a conservative method to treat ankylosed teeth for preservation of alveolar ridge prior to permanent prosthetic reconstruction: literature review and case presentation

Abstract –  Avulsed teeth that are stored extraorally in a dry environment for >60 min generally develop replacement root resorption or ankylosis following their replantation due to the absence of a vital periodontal ligament on their root surface. One negative sequelae of such ankylosis is tooth infra-positioning and the local arrest of alveolar bone growth. Removal of an ankylosed tooth may be difficult and traumatic leading to esthetic bony ridge deformities and optimal prosthetic treatment interferences. Recently a treatment option for ankylosed teeth named 'de-coronation' gained interest, particularly in pediatric dentistry that concentrated in dental traumatology. This article reviews the up-to-date literature that has been published on decoronation with respect to its importance for future prosthetic rehabilitation followed by a case presentation that demonstrates its clinical benefits.     

Bone morphology after delayed tooth replantation – case series

The purpose of this report was to describe the morphological changes in the alveolar bone after delayed replantation of avulsed teeth using three dimensional cone‐beam computed tomography in 11 during the time period 2003–2012. The radiographic observations revealed the following: Delayed replantation results in ankylosis‐related replacement root resorption; the resorption is delayed or arrested around the cervical area superior to the alveolar crest. The buccal bone is reduced in thickness but not the palatal bone. The buccal bone resorption of the alveolar crest progresses approximately to the root canal space of the ankylosed root. Delayed replantation does not completely maintain the bone volume. The buccal profile of alveolar bone in the maxillary anterior region is depending on teeth with viable periodontal ligament.     

Moving an ankylosed central incisor using orthodontics, surgery and distraction osteogenesis

When a dentist replants an avulsed tooth, the repair process sometimes results in the cementum of the root and the alveolar bone fusing together, with the replanted tooth becoming ankylosed. When this occurs, the usual process of tooth movement with bone deposition and bone resorption at the periodontium cannot function. If dental ankylosis occurs in the maxillary incisor of a growing child, the ankylosed tooth also cannot move vertically with the subsequent vertical growth of the alveolar process. This results in the ankylosed tooth leaving the plane of occlusion and often becoming esthetically objectionable. This report describes a 12-year-old female with a central incisor that was replanted 5 years earlier, became ankylosed, and left the occlusal plane following subsequent normal vertical growth of the alveolar process. When growth was judged near completion, the tooth was moved back to the occlusal plane using a combination of orthodontics, surgical block osteotomy, and distraction osteogenesis to reposition the tooth at the proper vertical position in the arch. This approach had the advantage of bringing both the incisal edge and the gingival margin of the clinical crown to the proper height in the arch relative to their antimeres. Previous treatment procedures for ankylosed teeth have often involved the extraction of the affected tooth. When this is done, a vertical defect in the alveolar process results that often requires additional bone surgery to reconstruct the vertical height of the alveolar process. If the tooth is then replaced, the replacement tooth must reach from the final occlusal plane to the deficient ridge. This results in an excessively long clinical crown with a gingival height that does not match the adjacent teeth.     

Decoronation: indications and treatment timing

Dental trauma in children is a frequent event and may involve functional, esthetic and orthodontic complications. Replacement resorption and ankylosis are frequently diagnosed following avulsion and replantation, severe intrusive luxation, and less frequently as a consequence of lateral luxations and root fractures. The optimal treatment for an ankylotic permanent incisor is yet to be found. The treatment of ankylosis and replacement resorption of a permanent incisor following dental trauma is further complicated when it involves a growing child. It is often associated with increasing infraposition of the tooth, retarded growth of the alveolar bone and tilting of adjacent teeth. To avoid such complications an ankylosed tooth should be removed before they changes become so pronounced that they necessitate orthodontic intervention and compromise future prosthetic treatment. The purpose of this article is to review the literature dealing with the considerations involved in the treatment of a permanent incisor diagnosed with replacement resorption and ankylosis. Different treatment options are considered. Decoronation is described and discussed.     

Treatment of replacement resorption with Emdogain® − a prospective clinical study

The present clinical study investigated the outcome of intentional replantation using Emdogain for periodontal healing following trauma‐related ankylosis. Sixteen ankylosed teeth affected by replacement resorption were treated as follows: After tooth extraction, the root canal was obturated with a retrograde titanium post. Emdogain was applied to the root surface and into the extraction socket with subsequent replantation of the tooth. Evaluation parameters included horizontal and vertical Periotest scores, percussion sound and periapical radiographs. All findings were compared to those of the adjacent teeth. The mean follow‐up period was 15 months (range 4–24 months). Eleven teeth showed no signs of recurrence of ankylosis: they were in full function and exhibited no pathological clinical findings. Four severely traumatized teeth demonstrated a recurrence of ankylosis after a mean period of 6 months, one tooth was lost in a second accident after 7 months. The estimated probability of 1 year without recurrence of ankylosis was P = 0.66 (95% confidence interval [0.40; 0.94]). The mean survival time was 10.2 months (SD 1.1). The results indicate that treatment of replacement resorption following light to moderate trauma with replantation and Emdogain appears to prevent or delay recurrence of ankylosis in many cases.     

The Problem Of Dentoalveolar Ankylosis And Subsequent Replacement Resorption In The Growing Patient

Dentoalveolar ankylosis is a serious complication following injuries of the periodontal membrane in severe dental trauma such as avulsion and intrusion. The condition is a fusion of the alveolar bone with the tooth. The consequences of this condition are progressive resorption of the root with replacement by bone (replacement resorption) and arrested growth of the alveolar process in the growing patient. This article will present an overview of dentoalveolar ankylosis and replacement resorption and its problems, treatment options and prognosis. especially focusing on the growing patient.     

Treatment of replacement resorption with Emdogain®– preliminary results after 10 months

Abstract – Ankylosis of traumatized teeth in children and adolescents may inhibit further development and growth of the corresponding jawbone. Therefore, ankylosed teeth should be removed. As an alternative treatment option to autotransplantation of a premolar, intentional replantation using Emdogain^® may be considered, provided the ankylosis is detected at an early stage or has only affected a small area of the root. Eleven ankylosed teeth presenting with replacement resorption were treated as follows: after tooth extraction, the root canal was treated extraorally and obturated by retrograde insertion of a titanium post. Emdogain was applied to the root surface and into the extraction socket with subsequent replantation of the tooth. During a mean follow-up period of 6.3 months, no signs of recurrence of ankylosis were noted. The horizontally and vertically measured Periotest scores were identical to those obtained on the adjacent teeth. These results suggest that intentional replantation using Emdogain may prevent or delay ankylosis of these replanted teeth.     

Decoronation for the management of an ankylosed young permanent tooth.

Replacement resorption rate is a variable process, and is dependent on age, basal metabolic rate, extra-alveolar time, treatment prior to replantation, amount of root dentin, severity of trauma, and extent of periodontal ligament necrosis. In patients 7-16 years old a tooth is lost 3-7 years after the onset of root resorption. The complications that may develop as a consequence of ankylosis of a permanent incisor in children are due to the inevitable early loss of the traumatized tooth and local arrest of alveolar bone development. An ankylosed tooth should be removed before the changes become so pronounced that they compromise future prosthetic treatment. The treatment options may involve: interceptive regenerative treatment, early extraction of the ankylosed tooth, orthodontic space closure, intentional replantation, extraction of the ankylosed tooth followed with immediate ridge augmentation/preservation, auto-transplantation, single tooth dento-osseous osteotomy, and decoronation. The purpose of this article was to review the considerations involved in the decision-making concerning the use of the decoronation technique for the treatment of a permanent incisor diagnosed as ankylosed.     

年轻恒牙外伤性牙齿固连研究进展

牙齿固连（tooth ankylosis）或替代性吸收（replacement resorption）是继发于严重牙外伤的一种常见并发症。对于年轻恒牙,外伤性牙齿固连使患牙低于邻牙正常牙合平面、局部牙槽骨发育停止、邻牙倾斜、牙弓不规则、牙弓长度丧失等,这些严重影响了患儿的美观,不利于后期永久修复的实施。目前尚无理想的办法阻止其发生及进展,截冠术被认为是治疗年轻恒牙外伤性牙齿固连的最佳方法。文章就年轻恒牙外伤性牙齿固连的临床表现、发生机制、进展的相关因素、治疗方法几个方面做一综述,以期为临床研究提供参考。     

年轻恒牙外伤性牙齿固连研究进展

 牙齿固连（tooth ankylosis）或替代性吸收（replacement resorption）是继发于严重牙外伤的一种常见并发症。对于年轻恒牙，外伤性牙齿固连使患牙低于邻牙正常牙合平面、局部牙槽骨发育停止、邻牙倾斜、牙弓不规则、牙弓长度丧失等，这些严重影响了患儿的美观，不利于后期永久修复的实施。目前尚无理想的办法阻止其发生及进展，截冠术被认为是治疗年轻恒牙外伤性牙齿固连的最佳方法。文章就年轻恒牙外伤性牙齿固连的临床表现、发生机制、进展的相关因素、治疗方法几个方面做一综述，以期为临床研究提供参考。     

Ankylosed teeth as abutments for maxillary protraction: a case report

It has been recognized that using the maxillary teeth to deliver extraoral force to the maxilla not only results in sutural remodeling but also periodontal remodeling and tooth movement. In patients with severe maxillomandibular malrelationships, the potential for tooth movement often limits the amount and duration of extraoral force and, consequently, affects the success of treatment. This case report describes a technique to intentionally ankylose deciduous teeth in a patient with severe maxillary retrusion. The ankylosed teeth were used as abutments to deliver an anteriorly directed intermittent extraoral force. After 12 months of treatment, the anterior crossbite was nearly corrected. At that point the ankylosed teeth loosened because of root resorption and the treatment was terminated. Cephalometric superimposition demonstrated that the occlusal correction was the result of anterior maxillary movement with little mandibular growth and no movement of the ankylosed teeth. The results suggest that intentionally ankylosed teeth may be used as abutments for extraoral traction in patients with a severe disturbance in maxillary growth.     

Decoronation of an ankylosed permanent incisor: alveolar ridge preservation and rehabilitation by an implant supported porcelain crown

Abstract –  Replacement resorption and ankylosis are frequently diagnosed following severe dental trauma. The complications that may develop as a result of ankylosis of a permanent incisor in children and adolescent include: esthetic compromise, orthodontic complications because of: arch irregularity; lack of mesial drift; tilting of adjacent teeth, arch length loss and local arrest of alveolar ridge growth. To avoid such complications, an ankylosed tooth should be removed before the changes become so pronounced that they compromise future prosthetic treatment. The purpose of this article was to present a case of preservation of the alveolar ridge for implant rehabilitation by utilizing decoronation for the treatment of a young permanent central incisor. An implant was inserted, without any bone augmentation procedures, followed by prosthetic porcelain crown rehabilitation. We conclude that treatment of an ankylosed young permanent incisor by decoronation may maintain the alveolar bone ridge width, height and continuity, and facilitate future rehabilitation with minimal, if any, ridge augmentation procedures.     

Decoronation of an ankylosed tooth for preservation of alveolar bone prior to implant placement*

Abstract – A 12‐year‐old patient sustained avulsions of both permanent maxillary central incisors. Subsequently, both teeth developed replacement resorption. The left incisor was extracted alio loco. The right incisor was treated by decoronation (removal of crown and pulp, but preservation of the root substance). Comparison of both sites demonstrated complete preservation of the height and width of the alveolar bone at the decoronation site, whereas the tooth extraction site showed considerable bone loss. In addition, some vertical bone apposition was found on top of the decoronated root. Decoronation is a simple and safe surgical procedure for preservation of alveolar bone prior to implant placement. It must be considered as a treatment option for teeth affected by replacement resorption if tooth transplantation is not feasible.     

Periodontal healing after replantation and autotransplantation of incisors in monkeys

The effect of injury to the cemental or alveolar part of the periodontal ligament upon periodontal healing after replantation and autotransplantation of teeth was studied in green Vervet monkeys. Sixty-six maxillary central incisors were replanted or autotransplanted after extra-alveolar periods of 18 min. saline storage or 120 min. dry storage. The animals were sacrificed after 8 weeks and the teeth examined histometrically. Identical healing was found in the following experimental groups: replantation or autotransplantation after 18 min. and replantation with or without removal of periodontal ligament in the alveolus. A significant increase in replacement resorption (ankylosis) compared to the 18 min. replantation group was found in the following groups: replantation and autotransplantation after 120 min., replantation after removal of periodontal ligament on the root surface and autotransplantation after 120 min. to a socket where the tooth was extracted 18 min. earlier. Autotransplantation after 18 min. to a socket where a tooth had been extracted 120 min. earlier led to a significant increase in the amount of replacement resorption compared to transplantation to an 18 min. socket. Based on these findings, it is concluded that the presence of an intact and viable periodontal ligament on the root surface is the most important factor in assuring healing without root resorption. The length of the extra-alveolar period also seems to exert some influence upon the socket, enhancing the development of ankylosis.     

Long-term results after intentional tooth reimplantation in monkeys.

The purpose of this study was to evaluate histologically the long-term response to intentional tooth reimplantation in six rhesus monkeys. The study revealed that cervical and apical root resorption is a universal complication after tooth reimplantation and that arrested areas of resorption will show repair by deposition of cementum. A highly cellular periodontal membrane usually will develop. Periodontal fibers will reattach to reparative bone and cementum but seldom regain functional orientation. Partial or complete ankylosis may result. A further complication is progressive undermining resorption of the ankylosed teeth. Long-term studies are mandatory to evaluate the response to intentional tooth reimplantation.     

Long-term follow-up of maxillary incisors with severe apical root resorption

The purpose of the study was to analyse the mobility of teeth with severe orthodontically induced root resorption, at follow-up several years after active treatment, and to evaluate mobility in relation to root length and alveolar bone support. Seventy-three maxillary incisors were examined in 20 patients, 10-15 years after active treatment in 13 patients (age 24-32 years) and 5-10 years after active treatment in seven patients (age 20-25 years). All had worn fixed or removable retainers; seven still had bonded twistflex retainers. Total root length and intra-alveolar root length were measured on intra-oral radiographs. Tooth mobility was assessed clinically according to Miller's Index (0-4) and the Periotest method. Crestal alveolar bone level, periodontal pocket depth, gingival, and plaque indices, occlusal contacts during occlusion and function, and dental wear were recorded. There was a significant correlation (P < 0.05) between tooth mobility, and total root length and intra-alveolar root length. No correlation was found between tooth mobility and retention with twistflex retainers. None of the variables for assessment of periodontal status, occlusion and function were related to total root length or tooth mobility. It is concluded that there is a risk of tooth mobility in a maxillary incisor that undergoes severe root resorption during orthodontic treatment, if the remaining total root length is < or = 9 mm. The risk is less if the remaining root length is > 9 mm. Follow-up of teeth with severe orthodontically induced root resorption is indicated.     

Treatment of ankylosed maxillary central incisors by single-tooth dento-osseous osteotomy and alveolar bone distraction

When tooth ankylosis occurs in growing children, the ankylosed tooth fails to erupt and gradually positions itself below the occlusal plane. This causes functional and esthetic problems, and orthodontic treatment is often impossible. To clarify this problem, we developed a new treatment protocol for the movement of ankylosed teeth. This consists of single-tooth dento-osseous osteotomy and alveolar bone distraction using orthodontic multibracket appliances. A special distraction device is not required, thus reducing the burden to patients. Two cases in which an ankylosed maxillary central incisor was successfully treated with this protocol are presented.     

The effect of orthodontic extrusion on traumatically intruded teeth

The management of traumatically intruded permanent incisors is controversial. Some authors suggest a decreased incidence of ankylosis in cases treated with orthodontic extrusion. The purpose of this study was to examine two common management techniques for traumatic intrusion, orthodontic extrusion, and observation for re-eruption. The four first premolars of three shepherd dogs were traumatically intruded with a mallet while a holding device was used to prevent tooth fracture. Five to 7 days following the injury, orthodontic force was applied unilaterally while the contralateral tooth served as the untreated control. To facilitate serial periapical radiography, x-ray jigs were fabricated for each animal and tantalum implants were placed in the bone distal to the permanent canine and first and second premolars. Observations included radiographic measurement of tooth movement, clinical estimates of tooth mobility, and radiographic and histologic assessment of root resorption, ankylosis, and periapical pathosis. The amount of traumatic intrusion varied from less than 0.5 to 4.1 mm. Following 11 to 13 weeks of force activation, 10 of 12 traumatized teeth showed clinical, radiographic, and histologic evidence of ankylosis irrespective of orthodontic treatment. Whereas the ankylosed teeth did not move with orthodontic forces, the teeth used for force application were orthodontically intruded 1.7 to 6.5 mm. When the injury to the tooth was severe, orthodontic extrusion had little effect on repositioning of the injured tooth but resulted in undesirable movement of the anchorage teeth. When the injury was less severe, orthodontic forces facilitated repositioning of the affected tooth.     

Treatment of an ankylosed central incisor by single tooth dento-osseous osteotomy and a simple distraction device.

When teeth are replanted after being avulsed, the repair process sometimes results in ankylosis. In a growing child, the ankylosed tooth fails to move along with the remaining alveolar process during vertical growth, resulting in a tooth that gradually appears more and more impacted and requires several reconstructive procedures to correct. Ankylosed teeth can, however, serve as anchorage for orthodontic correction of a malocclusion and as a point of force application for a dentoalveolar segment during alveolar distraction osteogenesis. This case report describes the treatment of a 13-year-old girl whose maxillary left central incisor had been avulsed and replanted 5 years earlier. The tooth had become ankylosed, and it was used to provide "free anchorage" during distalization of the maxillary dentition. The underdeveloped alveolar process adjacent to the ankylosed tooth was reconstructed by dento-osseous segment distraction osteogenesis, by using the ankylosed tooth as the point of force application.