Tooth mobility

Tooth mobility is the horizontal or vertical displacement of a tooth beyond its normal physiological boundaries around the gingival area, i.e. the medical term for a loose tooth.
Tooth loss implies in loss of several orofacial structures, such as bone tissues, nerves, receptors and muscles and consequently, most orofacial functions are diminished. Damage to the supporting tissues of the teeth may progress to necrosis of the alveolar bone, resulting in tooth loss.

Classification

Mobility is graded clinically by applying pressure with the ends of two metal instruments and trying to rock a tooth gently in a bucco-lingual direction. Using the fingers is not reliable as they are too compressible and will not detect small increases in movement. The location of the fulcrum may be of interest in dental trauma. Teeth which are mobile about a fulcrum half way along their root likely have a fractured root.
Normal, physiologic tooth mobility of about 0.25 mm is present in health. This is because the tooth is not fused to the bones of the jaws, but is connected to the sockets by the periodontal ligament. This slight mobility accommodates forces on the teeth during chewing without damaging them. Milk teeth also become looser naturally just before their exfoliation. This is caused by gradual resorption of their roots, stimulated by the developing permanent tooth underneath.
Abnormal, pathologic tooth mobility occurs when the attachment of the periodontal ligament to the tooth is reduced, or if the periodontal ligament is inflamed. Generally, the degree of mobility is inversely related to the amount of bone and periodontal ligament support left.
Grace & Smales Mobility Index

Grade 0: No apparent mobility
Grade 1: Perceptible mobility <1mm in buccolingual direction
Grade 2: >1mm but <2mm
Grade 3: >2mm or depressibility in the socket

Miller Classification

Class 1: < 1 mm
Class 2: > 1 mm
Class 3: > 1 mm
Causes

Pathological

There are a number of pathological diseases or changes that can result in tooth mobility. These include periodontal disease, periapical pathology, osteonecrosis and malignancies.

Periodontal disease

is caused by inflammation of the gums and the supporting tissue due to dental plaque.
Periodontal disease is commonly caused by a build up of plaque on the teeth which contain specific pathological bacteria. They produce an inflammatory response that has a negative effect on the bone and supporting tissues that hold the teeth in place. One of the effects of periodontal disease is that it causes bone resorption and damage to the supportive tissues. This results in a loss of structures to hold the teeth firmly in place and they then become mobile. Treatment for periodontal disease can stop the progressive loss of supportive structures but it can not regrow bone to make teeth stable again.

Periapical pathology

In cases where periapical pathology is present, teeth also may have increased mobility. Severe infection at the apex of a tooth can again result in bone loss and this in turn can cause mobility. Depending on the extent of damage the mobility may reduce following endodontic treatment. If the mobility is severe or caused by a combination of reasons then mobility may be permanent.

Osteonecrosis

is a condition in which lack of blood supply causes the bone to die off. It mainly presents following radiotherapy to the jaw or as a complication in patients taking specific anti-angiogenic drugs. As a result of this necrosis the patient might experience several symptoms including tooth mobility.

Oral cancer

is a malignant abnormal excessive growth of cells within the oral cavity, which arises from premalignant lesions through a multistep carcinogenesis process. Most oral cancers involve the lips, lateral border of the tongue, floor of the mouth, and the area behind the third molars, i.e. the retromolar area. Symptoms of oral cancer can include velvety red patches and white patches, loose teeth with no apparent cause and non-healing mouth ulcers. Risk factors for oral cancer may include caries prevalence, oral hygiene status, dental trauma, dental visit, stress, family history of cancer, and body mass index. Habits such as tobacco chewing/smoking and alcohol are the major causative agents, although human papillomavirus has also recently been implicated as one of them. Alcohol itself is not carcinogenic but it potentiates the effects of carcinogens by increasing the permeability of the oral mucosa.

By far the most common cause of loss of attachment is periodontal disease. This is painless, slowly progressing loss of bony support around teeth. It is made worse by smoking; the treatment is by improving the oral hygiene above and below the gumline.
Dental abscesses can cause resorption of bone and consequent loss of attachment. Depending on the type of abscess, this loss of attachment may be restored once the abscess is treated, or it may be permanent.
Many other conditions can cause permanent or temporary loss of attachment and increased tooth mobility. Examples include Langerhans cell histiocytosis.
Parafunctional habits

, which is an abnormal repetitive movement disorder characterised by jaw clenching and tooth grinding, is also a causative factor in the development of dental issues, including tooth mobility. Although it cannot cause periodontium damage in itself, bruxism is known to be able to worsen attachment loss and tooth mobility if periodontal disease is already present. Moreover, the severity of tooth mobility caused by bruxism also varies depending on the teeth grinding pattern and intensity of bruxism. However, the tooth mobility is typically reversible and the tooth returns to normal level of mobility once the bruxism is controlled.

Dental trauma

refers to any traumatic injuries to the dentition and their supporting structures. Common examples include injury to periodontal tissues and crown fractures, especially to the central incisors. These traumas may also be isolated or associated with other facial trauma. Luxation injury and root fractures of teeth can cause sudden increase in mobility after a blow. However, this depends on the type of dental trauma, as clinical findings show some types of trauma may not affect mobility at all. For example, while a subluxation or alveolar fracture would cause increased mobility, an enamel fracture or enamel-dentin fracture would still show normal mobility.

Physiological

Physiological tooth mobility is the tooth movement that occurs when a moderate force is applied to a tooth with an intact periodontium.
Causes of tooth mobility other than pathological reasons are listed below:

Hormonal

Hormones play a vital role in the homeostasis within the periodontal tissues. It has been advocated for a number of years that pregnancy hormones, the oral contraceptive pill and menstruation can alter the host response to invading bacteria, especially within the periodontium, leading to an increase in tooth mobility. This has been presumed to be as a result of the physiological change within the structures surrounding the teeth. In a study conducted by Mishra et al, the link between female sex hormones, particularly in pregnancy, and tooth mobility was confirmed. It was found that the most substantial change in mobility occurred during the final month of gestation.

Occlusal trauma

Excessive occlusal stresses refer to forces which exceed the limits of tissue adaptation, therefore causing occlusal trauma. Tooth contact may also cause occlusal stress in the following circumstances: parafunction/bruxism, occlusal interferences, dental treatment and periodontal disease. Although occlusal trauma and excessive occlusal forces does not initiate periodontitis or cause loss of connective tissue attachment alone, there are certain cases where occlusal trauma can exacerbate periodontitis. Moreover, pre-existing plaque-induced periodontitis can also cause occlusal trauma to increase the rate of connective tissue loss, which in turn may increase tooth mobility.

Primary tooth exfoliation

When primary teeth are near exfoliation there will inevitably be an increase in mobility. Exfoliation usually occurs between the ages of six and thirteen years. It usually starts with the lower anterior teeth ; however, exfoliation times of the primary dentition can vary. The timing depends on the permanent tooth underneath.

Dental treatments

A common scenario of dental treatment causing aggravation of tooth mobility is with a new filling or crown which is a fraction of a millimetre too prominent in the bite, which after a few days causes periodontal pain in that tooth and/or the opposing tooth. Orthodontic treatment can cause increased tooth mobility as well. One of the risks of orthodontic treatment, as a result of inadequate access for cleaning, is gingival inflammation. This is most likely to be seen in patients with fixed appliances. Some loss of connective tissue attachment and alveolar bone loss is normal during a two-year course of orthodontic treatment. This does not usually cause problems as it is slight and will resolve after treatment; however, if oral hygiene is inadequate and the patient has a genetic susceptibility to periodontal disease, the effect can be more severe. Another risk of orthodontic treatment that can lead to an increase in mobility is root resorption. The risk of this is thought to be greater if the following factors are present:

Radiographic evidence of previous root resorption
Roots of short length prior to orthodontic treatment
Previous trauma to the tooth
Iatrogenic: use of excessive forces during orthodontic treatment
Management

The treatment of tooth mobility depends on the aetiology and the grade of mobility. The cause of mobility should be addressed to obtain an optimal treatment outcome. For example, if the tooth mobility is associated with periodontitis, periodontal treatment should be carried out. In the presence of a periapical pathology, treatment options include drainage of abscess, endodontic treatment or extraction.
Occlusal adjustment
Occlusal adjustment is the process of selectively modifying occlusal surfaces of teeth through grinding to eliminate disharmonious occlusion between upper and lower teeth. Occlusal adjustment is only indicated when mobility is associated with periodontal ligament widening. Occlusal adjustments will be unsuccessful if the mobility is caused by other aetiology such as loss of periodontal support or pathology.
Splinting
This is the procedure of increasing resistance of tooth to an applied force by fixing it to a neighbouring tooth or teeth. Splinting should only be done when other aetiologies are addressed, such as periodontal disease or traumatic occlusion, or when treatments are difficult due to the lack of tooth stabilization. Splinting allows healing and functions during tissue healing. The main disadvantage of splinting is it makes removal of plaque more difficult, as there will be increased plaque retention at the margins of the splint, which can cause periodontal disease and further loss of periodontal support. A dental splint works by evening out pressure across a patient's jaw. A splint can be used to protect teeth from further damage as it creates a physical barrier between lower and upper teeth. In order to treat mobility, teeth can be joined or splinted together in order to distribute biting forces between several teeth rather than the individual mobile tooth. A splint differs from a mouthguard as a mouth guard covers both gums and teeth to prevent injury and absorb shock from falls or blows.