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.     

Intentional Replantation with an Atraumatic Extraction System in Teeth with Extensive Cervical Resorption

External cervical resorption (ECR) often renders a tooth nonrestorable, especially if it extends deeply within the dental hard tissue. Intentional replantation is sometimes performed as the last resort to save the tooth but may limit conventional forceps extraction because of the high risk of periodontal ligament cell damage or crown fracture.This case report describes the intentional replantation of an upper central incisor with extensive ECR using an axial, atraumatic extraction system to save the otherwise hopeless tooth. The patient was an asymptomatic 37-year-old man with no contributing medical history. The treatment protocol included atraumatic extraction followed by granulation tissue removal, extraoral root canal treatment, and adhesive restoration of the extensive resorption defect. During extraoral manipulation, the utmost care was taken to prevent root surface drying, contamination with dental adhesive, or heat-induced periodontal ligament damage during curing. Two and a half years after replantation, clinical and radiographic examinations revealed normal healing and no symptoms but a slight reduction of bone level compared with the preoperative level and no signs of root resorption or ankylosis. The successful outcome in this case supports the idea of performing intentional replantation with an atraumatic extraction system to save teeth with extensive cervical root resorption and a high risk of fracture during extraction.     

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.     

Application of enamel matrix derivative in autotransplantation of an impacted maxillary premolar: a case report

BACKGROUND: The success of tooth transplantation or replantation depends on the viability of periodontal ligament in the planted tooth. Mechanical injury to periodontal tissues frequently results in dental root resorption and dental ankylosis, which leads to the failure of transplantation or replantation. Enamel matrix derivative (EMD) has been recently used to induce periodontal regeneration. In this report, we show a clinical case of EMD application in the transplantation of an inversely impacted and immature tooth. METHODS: An impacted second premolar was found in the right maxilla of a 16 year-old girl. The tooth was inversely impacted and the dental root was incomplete. When transplantation was carried out, EMD was applied to the periodontal tissues of the extracted premolar. The tooth was fixed at the correct position and the clinical condition was followed for evaluation for 6 months. RESULTS: Radiographs after 3 months exhibited new bone formation surrounding the transplanted tooth. After 6 months, considerable growth of dental root was evident, periodontal ligament-like radiolucency appeared, the vital reaction of the planted tooth was detected, and there were no signs of root resorption or ankylosis. CONCLUSION: Short-term results from this case indicate that EMD application was effective in the transplantation of an inversely impacted and immature tooth and that EMD might contribute to the growth of dental root and to the prevention of ankylosis.     

Delayed replantation of an avulsed tooth after 5 hours of storage in saliva: a case report

Abstract – This article reports a clinical case of a 8‐year‐old boy, who underwent an avulsion of the upper left central incisor. The avulsed tooth was kept in the oral cavity in direct contact with saliva for 5 h from the moment of trauma until its replantation. Treatment guidelines for avulsed mature permanent teeth were followed. The clinical and radiographic findings after 2 years revealed absence of root resorption, ankylosis or mobility of the replanted tooth.     

Intentional replantation of an immature permanent lower incisor because of a refractory peri-apical lesion: case report and 5-year follow-up

We performed an intentional replantation of an immature lower incisor that had a refractory peri-apical lesion. The incisor was extracted and the peri-apical lesion was removed by curettage. The root canal of the tooth was then rapidly irrigated, and filled with a calcium hydroxide and iodoform paste (Vitapex(R)), after which the tooth was fixed with an arch wire splint. Five years later, no clinical or radiographic abnormalities were found, and the root apex was obturated by an apical bridge formation. A team of two dentists is essential to prevent a prolonged operation time, thus eliminating any of the causes of ankylosis. Furthermore, calcium hydroxide and iodoform paste, along with an arch wire splint retained with composite resin, led to good healing of the periodontal tissue after the intentional replantation. Our results indicate that intentional replantation is a useful method for an immature tooth with refractory peri-apical problems.     

Intentional replantation for a periodontally involved hopeless incisor by using autologous platelet-rich plasma

The aim of the present case is to describe the use of autologous platelet-rich plasma (PRP) in an intentional replantation procedure for a periodontally involved lower right central incisor with 18 months follow-up. Brief information is also given on the preoperative preparation of PRP in the dental office. PRP preparation is a new biotechnology, and the prepared material contains thrombocyte concentrates and high levels of growth factors. This material promotes healing time in a range of various sites. In this case, a tooth with severe periodontal breakdown was treated with PRP with intentional replantation procedure. This tooth was previously treated with root canal treatment and root planing. The tooth was extracted, and was replanted with autologous PRP. Clinical and radiographic follow-up for 18 months demonstrated new bone formation around the apical portion of the root and all clinical parameters indicated a trend of healing. The mobility of this previously grade III mobile incisor returned to normal limits. We speculate that intentional replantation with PRP application may induce wound healing and may induce bone formation.     

16‐Year follow‐up of an avulsed maxillary central incisor after replantation following 10‐h storage: An unusual case

Tooth avulsion is a type of dental injury defined as the complete displacement of a tooth out of the alveolar socket, and the lack of prompt treatment measures can result in the loss of function, poor quality of life, and psychological and social problems. However, several factors may not permit the immediate replantation of an avulsed tooth; therefore, delayed replantation has emerged as an alternative to meet the esthetic, functional, and psychological demands of patients. Here it was described that the successful replantation of an avulsed maxillary central incisor in a 9‐year‐old boy who presented at the clinic with the tooth stored in unfavorable conditions as dry and then in olive oil‐milk mixture almost 10 h after the event. The tooth has remained in its socket healthy for 16 years after treatment. The patient was satisfied with both esthetics and function.     

Immediate self‐replantation of an avulsed permanent mandibular incisor – a case report

Abstract – Background: Approximately 50% of children under the age of 15 years are subjected to various kinds of injuries in the orofacial region. In the permanent dentition, the most severe dental injury affects the surrounding alveolar bone structure and leads to loss of the tooth. The current literature emphasizes that the awareness of appropriate triage procedures following dental trauma is unsatisfactory and that delay in treatment is the single most influential factor affecting prognosis. Results: This case report presents the immediate self‐replantation of a right lateral mandibular incisor of a 12‐year‐old male patient following a traumatic avulsion. The same patient had earlier, aged 10 years, experienced a trauma leading to the loss of all four maxillary incisors. The missing incisors were replaced by a removable acrylic denture. Having the requisite experience from the earlier accident, the child performed on himself an immediate replantation of the tooth at the site of the accident. After avulsion, the tooth was not splinted timely nor was an endodontic procedure carried out and no antibiotics were prescribed. The first dental examination after the trauma was performed 6 months later and since then, radiographic follow‐up has been introduced. One year after the trauma, following the late endodontic treatment performed 6 months after reimplantation, the tooth is asymptomatic and stable. Conclusions: Immediate self‐replantation of an avulsed tooth is the best treatment choice, even without any other proceeding treatment. However, the healing process should be followed up to allow for the treatment of the early signs of pulpal necrosis and/or root resorption.     

Continued root formation after replantation and root canal treatment in an avulsed immature permanent tooth: a case report

Abstract – This case report describes the continued root formation following replantation and conventional root canal therapy of a traumatically avulsed open‐apex tooth with suppurative apical periodontitis. A 7‐year‐old male patient had an avulsed upper left central incisor (tooth 21) replanted approximately 50 min after traumatic avulsion. A root canal procedure was initiated due to pulp necrosis and periapical abscess detected in the follow‐up period. After endodontic treatment with calcium hydroxide (Ca(OH)₂) dressing, a normal root length developed including an apical segment beyond the hard tissue barrier. Regeneration of the root occurred without pathology or ankylosis at 1‐year of follow up.     

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.     

Extraoral endodontic treatment, odontotomy and intentional replantation of a double maxillary lateral permanent incisor: case report and 6-year follow-up

AIM: To describe combined endodontic, surgical and orthodontic treatment of a maxillary lateral incisor fused with a supernumerary. SUMMARY: Double tooth is a dental irregularity consequent to fusion of two or more teeth or dental gemination. The teeth most commonly involved are deciduous, but in 0.1% of cases permanent teeth are affected, in which case aesthetic, functional and periodontal problems can result. This paper reports a clinical case of a double tooth in the position of the maxillary right lateral permanent incisor. Combined orthodontic, endodontic and surgical treatment (intentional replantation) allowed the tooth to be retained without periodontal compromise and with a positive orthodontic result both immediately and 6 years following intervention. *A conservative approach that addresses periodontal, pulpal and tooth tissues, can result in the retention of a double tooth. *Maintenance of the root and alveolar bone in young adults at least until full skeletal maturation should be the main treatment objective.     

全脱出恒牙再植预后临床研究进展

牙齿全脱出（tooth avulsion）是指牙齿受外力从牙槽窝中脱出，牙髓和牙周膜同时损伤，牙槽窝空虚或伴有牙槽骨骨折。全脱出是牙齿常见创伤类型之一，发生率约为0.5% ~ 16%，多发于7 ~ 14岁儿童，以上颌中切牙最常见。牙齿全脱出后，再植是目前临床最常用且首选的治疗方式。再植的牙齿预后受多种因素影响，如脱位牙的牙根发育情况、离体干燥时间等。全脱出牙的牙髓及牙周预后情况复杂多样，现将全脱出牙预后及相关影响因素做一综述。     

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.     

The effect of saline storage before replantation upon dry damage of the periodontal ligament

Abstract The effect of 30 min of saline storage before replantation of teeth, which had been dried out for 30 min, was studied in 10 Green Vervet monkeys (Cercopithecus aethiops). Maxillary central incisors were extracted and dried out for 30 min, after which 1 incisor was replanted and the other transferred to a saline solution for 30 min before replantation. No splinting or endodontic treatment was carried out. The teeth were examined after 8 wk. Histometric analysis showed identical extent of root resorption in the 2 groups, with ankylosis being the dominant resorption type, and with very limited pulpal repair in either group. It is concluded that saline storage under the experimental conditions chosen had no effect on development of root resorption or pulpal repair, presumably because 30 min dry storage had inflicted close to maximal damage on the periodontal ligament at the root surface. On the other hand, it is of clinical importance that a certain delay in the replantation procedure does not influence periodontal and pulpal healing, as long as the tooth is kept in saline storage. This suggests that replantation under these conditions can be reserved for dental professionals, rather than favoring immediate replantation by anyone ‘on-the-spot’.     

Vital reimplanted tooth in torsiversion: A one-and-half-year follow-up

A 10-year-old boy reported to the dental outpatient department with a chief complaint of a labially placed upper left central incisor and wanted treatment for esthetic reasons. No history of pain, bleeding, or any swelling was reported. Clinical examination revealed that the left upper central incisor was in torsoversion, that is, the palatal side of a tooth in labial position or a tooth rotated along its long axis by 180°. There was a history of traumatic avulsion followed by replantation 2.5 years earlier. No dental treatment was taken by the child. The radiograph showed root fracture in the apical one-third area but with no periapical radiolucent changes. As the tooth was completely asymptomatic and was vital with no periapical changes, no endodontic treatment was planned. Interceptive orthodontic treatment for the labially positioned tooth was undertaken followed by esthetic recontouring with labial crown forms. The case highlights the excellent results of immediate replantation. It also highlights the need for basic education about common dental emergencies, such as avulsion, to schoolchildren, teachers, and primary health-care providers.     

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.     

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.     

Preservation of alveolar bone of un-restorable traumatized maxillary incisors for future

Anterior maxillary implantation is a challenging treatment for both the surgeon and prosthodontist due to high esthetic demands in this area. However, it is the most traumatized and most exposed region to habits. Prompt and appropriate management can significantly improve prognosis of many dentoalveolar injuries, especially in young patients. Unfortunately, many traumatized teeth are overtreated or left untreated, which lead to a much more complicated treatment at the time of permanent restoration at adulthood. The facial cortical plate over the roots of the maxillary teeth is thin and porous. Periapical infections, as well as prolonged and stubborn surgical treatments (repeated root end surgeries) can cause resorption of the labial plate, migrate to a more palatal position, and may later require an augmentation procedure prior to implant placement. The treatment-options of traumatized, anterior maxillary, un-restorable fractured root and ankylosed infraocluded teeth, in relation to preservation of the adjacent alveolar bone for future use of dental implantation will be discussed. The recommended treatment of crown-root fracture of permanent incisor includes removal of the coronal fragment and supragingival restoration of the fractured root. In severe cases in which the fracture line positions deeply under the gingival margin, this treatment may be supplemented by gingivectomy and/or osteotomy, as well as surgical or orthodontic extrusion of the root. In young patients, use of these treatment options as temporary treatment to preserve the facial cortical plate is important. Preservation of alveolar dimension will enable implantation after the completion of growth and development. Dento-alveolar ankylosis accompanied by replacement resorption is a serious complication following severe injury to the periodontal membrane. This complication develops mainly following avulsion and intrusion but also following lateral luxation and root fracture. Replacement resorption develops after 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 bone and tooth. Following ankylosis, resorption of cementum and root dentin occurs. These processes eventually result in replacement of the entire root by bone. In young children it could arrest the growth of the alveolar process and create an infra-occluded tooth, resulting in a severe bony defect that is difficult to correct. In addition, loss of the maxillary incisor leads to serious esthetic and restorative problems, particularly when the trauma occurs at a young age. Therefore, ankylosed teeth should be treated as soon as diagnosed. Alternative treatments include intentional extraction and immediate replantation of the ankylosed tooth to its socket after embedding the tooth and the socket in Emdogain. This treatment is indicated only when the ankylosis or the replacement resorption is diagnosed at an early stage or has affected only a small area of the root. When the resorption is diagnosed at a later stage, auto transplantation of first lower pre-molar to the anterior region or decoronation of the ankylosed tooth may be considered. Decoronation is a simple and safe surgical procedure for preservation of alveolar bone prior to implant placement. It should be considered as a treatment option for teeth affected by replacement resorption. The alternative treatment of surgical extraction of an ankylosed tooth often leads to considerable bone loss and reduced bone volume in the oro-facial dimension. This may later necessitate an augmentation procedure. CONCLUSION: Scrupulous diagnosis of teeth and the alveolar bone after a traumatic injury is necessary. Treatment is multidisciplinary, requiring endodontic, surgical, orthodontic, operative and prosthetic compliance. An individual treatment plan for each patient is necessary. General rule do not apply. Periodic check-up is essential.     

Relationship of abnormalities in dental and skeletal development in the osteopetrotic (os) rabbit

Osteopetrosis is a metabolic bone disease characterized by reduced bone resorption of heterogenous cause. The rabbit mutation is lethal and exhibits ultrastructural aberrations in osteoclasts and osteoblasts together with hypocalcemia, hypophosphatemia and failure to be cured by bone marrow transplantation. We have studied dental abnormalities in mutants from birth to 3 wk using radiographic, cytologic and autoradiographic methods. Radiographs show hypoplasia of most teeth in mutants. The maxillary incisor is smaller and more curved and the mandibular incisor thin and straight compared to normal littermates. The first 3 molars in both arches are unerupted and of distorted shape while the last 2 are less affected. Microscopically areas of ankylosis of mutant incisors and the first 3 molars were commonly encountered even at birth. Osteoclasts were numerous. Autoradiograms of 3H-proline incorporation showed strong periosteal and weak endosteal labeling of bone in both mutants and normal littermates. Dentin labeling in mutant incisors and molars was not less than that in normal rabbits and sites of ankylosis in mutants exhibited labeling. These data indicate that osteopetrotic rabbits exhibit major aberrations in shape and eruption of incisors and most molars and that these effects are not due to lack of dentin formation. Early ankylosis, perhaps secondary to congenital reduction of bone resorption, appears to be the major cause of the dental abnormalities which are less severe in the youngest (posterior) teeth.