When the tooth is fused to the jawbones, it is referred to as ankylosed teeth. This article explains the causes, signs, diagnosis, and treatment of an ankylosed tooth.
An ankylosed tooth occurs when the root of a tooth is permanently attached to the bones of the jaw. In Greek, ankylosis means a lack of mobility. Generally, the root portion of a tooth is connected to the jaw bone by fibers called the periodontal ligament. But, an ankylosed tooth is directly connected to the bone because of the missing periodontal ligament. This periodontal ligament acts as a shock absorber to reduce the impact of forces on the bone and keeps the tooth fixed to the bone.
An ankylosed tooth cannot be differentiated from a normal tooth by looks, but sometimes, it may be lower or higher than the gum line. For example, ankylosis can occur when the teeth are still growing out of the gums. If such a condition occurs, the tooth is usually lower because the growth has been halted in mid-process.
Ankylosiscan occur due to the necrosis of the periodontal ligament. Following necrosis, bone formation will be along the denuded root surface area. Trauma and avulsion of teeth are the primary causes of injury. After avulsion, if the tooth is kept in a dry environment for a critical time, cell death can be on the root surface. The chances of reattachment of periodontal ligament to the affected area are also less than 20 %, thus leading to ankylosis.
The trauma of the tooth can happen in variable degrees, distribution, and forms. If the damage to the root surface is more than 20 %, it is followed by a reactive inflammatory response, which starts the healing process. This can lead to an area of cementum-devoid root surface. This area is susceptible to faster bone-forming cells that migrate and multiply. The infectious stimuli present in the root canal, such as bacterial endotoxins, pass from the root canal through the dentinal tubules and accessory canals to the external root surface, inducing inflammation-mediated resorption of the tissues of the root and adjacent bone.
Depending on the degree of severity, ankylosis can be classified as follows:
Mild Ankylosis - The tooth is a maximum of two millimeters below other teeth or in infra occlusion.
Moderate Ankylosis - The tooth infra erupts, but still, there will be some type of contact with the adjacent teeth.
Severe Ankylosis - Normally, in this type of ankylosis, the teeth do not erupt and are concealed within the jawbone.
There are different causes of an ankylosed tooth, including:
Tooth or jaw bone infection and inflammation.
Tooth injury or damage.
Gum disease that has been left untreated.
The pressure of the tongue directly on a particular tooth.
Genetics also play an important role in developing ankylosed teeth.
Mechanical damage to the cementoenamel junction.
Spaces between the membranes of the adjacent tooth.
The main symptoms of ankylosed teeth are:
An ankylosed tooth is generally shorter than the adjacent tooth as if it has not emerged fully.
Reduced number of teeth due to the absence of eruption of an ankylosed tooth.
Normal teeth have a very minute degree of mobility, but an ankylosed tooth completely lacks mobility.
A dental midline shift is possible to occur.
Retention of a deciduous tooth.
Crooked formation of teeth or misalignment of the teeth on the affected jaw can be seen.
The under-eruption of an ankylosed tooth will produce an over-eruption of the tooth in the opposing jaw.
Abnormality in the enamel of the tooth.
Ankylosis can cause many issues like spacing, abnormal positions of adjacent teeth, and misalignment and trigger other associated problems with eruption and development of the jaws.
A few potential complications that can occur from an ankylosed tooth are:
The inclination of adjacent teeth.
Loss of space.
An ankylosed tooth does not occlude with the teeth of the opposing arch.
Malocclusions like localized open bites or crowded teeth.
Problem with chewing.
If an ankylosed tooth is a milk tooth, retention of the upcoming permanent tooth within the jawbone can happen.
Facial skeletal structure deformation.
Relative mandibular prognathism (big mandible).
Posterior open bite (backmost upper and lower teeth not touching each other upon clenching).
Midline shift (line between the central incisors of upper and lower teeth do not coincide).
Vertical growth of the alveolar bone can be affected.
An increased risk of periodontal disease and tooth decay can occur due to poorly positioned teeth, making oral hygiene difficult.
In most cases, an ankylosed tooth can be diagnosed during an oral examination. The affected ankylosed tooth will often be shorter than the other tooth. A dentist may also tap on the tooth surface; the tooth that is fused to the bone will have a different sound than the rest of the teeth. A dental X-ray can also be used as a form of diagnosis.
The treatment of the ankylosed teeth depends on thenature, position, and state of the ankylosed tooth or teeth.In the case of ankylosed primary teeth, the most accepted treatment includes removing the ankylosed tooth for the development and eruption of the permanent teeth. It is then followed by surgery to expose and reposition the emerging permanent tooth.
Few other treatment techniques include:
Orthodontic Treatment - The treatment helps to ensure the proper positioning and alignment of an ankylosed tooth.
Luxation - In this procedure, the mechanical breakage of the ankylosed teeth is done without compromising the blood vessels at the apex. It is done using appropriate forceps by firmly grasping the tooth and gently rocking it in a backward and forward and side-by-side direction. After this process, the periodontal ligament is restored to allow eruption.
Corticotomy - It is a surgical procedure in which a small piece of surgically cut bone is used to reposition the ankylosed tooth.
Ostectomy - Localized ostectomy is a procedure in which the affected osseous (the tissues that have turned to bone) tissue is cut. This method works only if the ankylosis is in the crestal area because other positions will not be readily accessible to surgery.
Malocclusions, an improper eruption of the tooth, facial skeletal structure deformation, and periodontal diseases are dental issues caused by an ankylosed tooth. Hence, a proper dental checkup and treatment are required at the earliest opportunity to avoid mishaps for a healthy oral cavity.
The mandibular first primary molar is commonly and more frequently ankylosed than any other tooth, followed by the second primary molar with an increased prevalence in older children. Between the age of seven and eleven years, the is a high incidence of ankylosed primary teeth seen in children.
If the timely treatment is not given to primary ankylosed teeth, they will not fall spontaneously and can cause alveolar bone defects, arch-length loss, occlusal disturbances, and impacted permanent successors are the problems due to delayed removal of ankylosed teeth.
Impacted teeth are a tooth when it remains inside gum tissue or the bone and does not erupt properly. But an ankylosed tooth occurs when the root of the teeth is attached to the jaw bone. It is essential to treat an ankylosed tooth as soon as possible. If it is left untreated, ankylosed teeth can lead to numerous tooth-associated problems.
In cases of an ankylosed permanent tooth, it is possible to dislocate it and check if the fused bone will heal properly. If not healed well, the tooth will be completely resorbed into the alveolar bone. So the dentist usually extracts the ankylosed teeth and restores them with a dental bridge or dental implant.
During ankylosed tooth treatment, it does not need to be extracted all time if it is a permanent tooth. The other treatment options to choose are:
- Orthodontic treatment to reposition and alignment of the ankylosed tooth.
- Restorative material can be built under the gum surface to make the tooth in contact.
- Luxation of the tooth must be tried and checked for the development of periodontal ligament, if not, then a surgical extraction of the tooth is necessary.
- If multiple teeth are ankylosis, then bone graft and alveolar bone osteotomy will be recommended.
- If the tooth does not have any problem, then it is just monitored over time.
If the ankylosed tooth is extracted, a portion of surrounding bone structures will also be damaged in most cases and might be removed with the tooth. So the healing will take longer, more than four weeks.
Treatment of ankylosed teeth in children is usually the removal of the ankylosed tooth, which will help in the correct growth of the adult tooth. Then a space maintainer will be recommended to hold the space until the permanent tooth erupts.
The ankylosed teeth show no pain or sensitivity, it is often identified during a dental examination, while planning for orthodontic treatment, or while taking X-rays. The best way to handle an ankylosed tooth is to leave it as such if it does not cause any symptoms it is or remove it surgically.
Initially, the ankylosed tooth is tried to be removed by luxating it, if that is not possible, then surgical extraction is done by cutting the gums and trimming the surrounding bone. If multiple teeth ankylosis is present, then an alveolar bone osteotomy and bone grafting may be recommended.
In children with ankylosed teeth, the doctors will have a waiting period to check for any changes, then the teeth will be extracted, followed by space maintainers if needed.
Last reviewed at:
17 May 2022 - 5 min read
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