Tooth ankylosis is a dentoalveolar fusion characterized by the death of the periodontal ligament and the fusion of cement with the alveolus. During examination, the ankylosed tooth is missing or displaced in the marginal direction. There is a dental alveolar elongation of the antagonist, shortening of the dental arch. On radiography, the absence of a periodontal gap indicates ankylosis. Conservative treatment is carried out by restoring the height of the crown to the line of closure. If ankylosis interferes with the physiological change, or active resorption of the roots soldered to the bone is noted, tooth extraction is indicated.
ICD 10
K03.5 Tooth ankylosis
Meaning
Tooth ankylosis (dental ankylosis) is a pathological process accompanied by fusion of the alveolar bone with the root. In 60% of cases, ankylosis of the lower temporary molars is detected. Milk teeth ankylose 10 times more often than permanent ones, lower molars – more than 2 times more often than upper ones.
Pathology is diagnosed equally among female and male representatives. It is quite rare to find a kind of tooth ankylosis – an anomaly of eruption by the type of bone bridges, characterized by the adhesion of neighboring rudiments. Among children with white skin, pathology occurs in 4%, in dark-skinned – in 0.9%.
Causes
Due to the influence of a number of external and internal factors, regenerative processes fail in the periodontal ligament, which performs a supporting function. As a result, a fusion of cement with the alveolar bone is formed. Several theories of ankylosis development are described:
- Genetic predisposition. Tooth ankylosis refers to a family disease. If there are cases of dental-alveolar fusion in the family, the risks of ankylosis formation in children increase.
- Displacement of the equilibrium between the processes of resorption and repair. Normally, root resorption proceeds in waves, alternating with the period of bone neoplasm. During the reparative phase, a spike may develop between the wall of the well and the cement.
- Infection is the germ. The presence of an inflammatory focus in the periapical tissues of a temporary tooth causes damage to the rudiment of a permanent one, as a result of which the process of eruption is disrupted.
- Traumatic injury. In case of subluxation of the tooth or complete dislocation with subsequent replantation, engraftment can go according to the type of synostosis – bone fusion of the root cement with the alveolus. The reason is the death of periodontal tissues.
- Toxic effects. The use of resorcinol-formalin-based mass in pediatric dentistry for root canal obturation leads to a violation of root resorption during the physiological change of teeth.
Pathogenesis
Normally, root resorption is accompanied by bone repair along the periphery. If bone neoplasm prevails, ankylosis may occur. With the help of histological examination, it is possible to detect zones of newly formed bone tissue between the root surface and the wall of the well with a gradual complete replacement of the periodontal. In the absence of permanent teeth follicles, the resorption of ankylosed roots proceeds more slowly.
With trauma, ankylosis develops due to the death of the periodontal. Due to the exposure of the root surface, osteoclasts begin to come into contact with mineralized dentin – cement. This triggers the activation of resorptive processes without external stimulation. Instead of dentin, bone tissue is layered.
Resorcinol-formalin mixture has an irritating effect on periapical tissues due to the penetration of formaldehyde through the apex, which has a cytotoxic effect. The presence of chronic destructive periodontitis of the milk tooth leads to damage to the permanent rudiment. Lysis of the enamel epithelium stimulates compensatory processes – bone tissue is deposited in place of the resorbed enamel, due to which the follicle is fixed in an ankylosed state.
Symptoms
Dentoalveolar fusion can be diagnosed in a milk, removable, permanent bite. When ankylosing the rudiment of a temporary tooth, its place is partially occupied by tilted or partially displaced adjacent teeth. In addition to dental deformity, there is a violation of the eruption of a permanent tooth. The latter may not cut through at all due to a bone obstacle in its path or cut through in the wrong position.
The formation of cement fusion with the hole after the formation of roots in the milk or permanent bite leads to deformation of the occlusal plane. The causal tooth is located below the line conventionally drawn through the chewing surfaces and cutting edges.
Also, an ankylosed tooth can erupt, but at the same time partially remain retenated: the crown is covered with soft tissues from above, immersed in the mucous membrane. The development of bone cement-alveolar fusion in the replaceable bite disrupts the process of physiological change.
Complications
Tooth ankylosis leads to a delay in the timing of eruption. The presence of bone fusion contributes to the development of dental deformity: displacement and inclination of adjacent teeth, extension in the direction of the ankylosed antagonist. Since during the formation of bone fusion, the root is resorbed, being replaced by bone tissue, this reduces the support of the alveolar bone. During the period of jaw growth, tooth ankylosis disrupts the development of the alveolar process.
Diagnostics
Diagnosis of dental fusion requires an integrated approach. The diagnosis of ankylosis is made on the basis of complaints, physical examination data, radiography. The examination is carried out by a dentist in cooperation with an orthodontist. Diagnostics include:
- Inspection. Retention, dentofacial deformities are detected in the patient: slopes, medial displacement, shortening of the row. The ankylosed tooth is located in the infra-occlusion (below the occlusal plane), the antagonist is in the supra-occlusion (above the occlusal plane). The marginal gum is displaced in the apical direction.
- Percussion. With vertical percussion, a sonorous steady sound is heard. Healthy teeth sound more muffled, which is due to the absorption of sound waves by periodontal tissues. The use of this method is justified when at least 1/5 of the root is affected.
- Dental x-ray. On a targeted X-ray image, root resorption is diagnosed with the replacement of resorbed lacunae with bone, there is no periodontal gap. The study is more informative with the development of dental fusion after eruption.
- CT of the jaw. Carried out in order to identify the causes of retention. A three-dimensional image is necessary if there is a suspicion of bone occurrence of follicles, the presence of “bone bridges”.
Differentiate ankylosis with tumors: osteoma, cementoma. Anomalies of the development of hard tissues should also be excluded.
Treatment
Conservative treatment
The tactics depend on the etiology and the stage during which the cement-bone fusion was formed: before, after eruption or during resorption. In most cases, if an ankylosed tooth does not create an obstacle to permanent eruption, and there is no aesthetic defect, a wait-and-see tactic is shown.
If the milk ankylosed tooth has erupted, but is located below the occlusion line, an adhesive restoration is performed. The restoration of the crown part creates the load necessary to stimulate complete eruption. For the same purpose, partially incised ankylosed temporary teeth are covered with thin-walled stamped crowns. In addition to activating the processes of eruption, it is possible to normalize occlusion, avoid the formation of deformities.
Surgical treatment
If a tooth ankylosis of a permanent tooth is diagnosed, which is in a retented position, the crown part is surgically exposed and the height is restored to the occlusion line with cement or other filling mass. Whether or not to remove a permanent tooth with ankylosis depends on the speed of resorptive processes. With the rapidly progressive resorption of ankylosed roots, the displacement of the gingival margin apically violates aesthetics, therefore removal is indicated. With the fusion of the roots at the resorption stage and the presence of a permanent tooth follicle, the causal tooth is removed.
Prognosis and prevention
The prognosis depends on etiological factors, the rate of resorption, the presence of rudiments of permanent teeth. Dental deformities associated with genetic pathology are more difficult to correct orthodontically. With rapidly increasing resorption, the prognosis is unfavorable. If there is no permanent tooth germ, the ankylosed roots of the milk are resorbed very slowly. Pathological resorption in ankylosis of traumatic etiology, occurring with a lesion of less than 20% of the root, can independently stop.
Prevention is aimed at timely treatment, elimination of focal and perifocal foci of chronic infection, proper management of patients after injuries accompanied by subluxation and complete dislocation. Bioinert materials should be used for channel obturation.