Tooth mobility

Tooth mobility is the medical term for loose tooth.

Tooth mobility
1: Total loss of attachment (clinical attachment loss, CAL) is the sum of 2: Gingival recession, and 3: Probing depth (using a periodontal probe)


Mobility is graded clinically by applying pressure with the ends of 2 metal instruments (e.g. dental mirrors) and trying to rock a tooth gently in a bucco-lingual direction (towards the tongue and outwards again). Using the fingers is not reliable as they are too compressible and will not detect small increases in movement.[1]:184 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.[1]:184

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 is to accommodate forces on the teeth during chewing without damaging them.[2]:55 Milk (deciduous) teeth also become looser naturally just before their exfoliation.[1]:197 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 (attachment loss, see diagram), or if the periodontal ligament is inflamed.[1]:220 Generally, the degree of mobility is inversely related to the amount of bone and periodontal ligament support left.

Grace & Smales Mobility Index[3]

  • 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(Horizontal)
  • Class 2: > 1 mm(Horizontal)
  • Class 3: > 1 mm (Horizontal+vertical mobility)



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

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 your teeth in place. One of the effects of periodontal disease is that it causes bone resorption and damage to the supportive tissues. This then 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 to bone to make teeth stable again.[4]

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.[5] 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.[6] As a result of this necrosis the patient might experience several symptoms including tooth mobility.[7]

Oral cancer

Oral cancers have a range of symptoms including red and white patches, ulcer and non-healing sockets. Another symptom that patients might experience is loose teeth with no apparent cause.[8]

Loss of attachment:

  • By far the most common cause is periodontal disease (gum disease). This is painless, slowly progressing loss of bony support around teeth. It is made worse by smoking and 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.[2]:35

Parafunctional Habits

  • Bruxism (abnormal clenching and grinding of teeth) can aggravate attachment loss and tooth mobility if periodontal disease is already present.[2] The tooth mobility is typically reversible and the tooth returns to normal level of mobility once the bruxism is controlled.

Dental trauma

  • Luxation injury and root fractures of teeth can cause sudden mobility after a blow. Dental trauma may be isolated or associated with other facial trauma.[9]

Physiological causes

Physiological tooth mobility is the tooth movement that occurs when a moderate force is applied to a tooth with an intact periodontium.[10]

Causes of tooth mobility other than pathological reasons are listed below:


Hormones play a vital role in the homeostasis within the periodontal tissues.[11] 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.[12]

Occlusal trauma

Excessive occlusal stresses are: “forces which exceed the limits of tissue adaptation, therefore cause occlusal trauma.”[13] Tooth contact can cause occlusal stress in the following circumstances: parafunction/ bruxism,[14] occlusal interferences, dental treatment and periodontal disease. Bruxism is excessive teeth grinding or jaw clenching.[15] An occlusal interference is a contact between teeth which inhibit smooth jaw closing movement along any path to intercuspal position.[16] An example of this would be over-eruption of a tooth following loss of its opposing counterpart.[17] Occlusal trauma can be primary or secondary.[18]

Primary Tooth Exfoliation

When primary teeth are near exfoliation there will inevitably be an increase in mobility.

Dental treatments

A common scenario is a new filling or crown which is a fraction of a millimeter too prominent in the bite, which after a few days causes periodontal pain in that tooth and/or the opposing tooth.[1]:220 Orthodontic treatment can cause increased in tooth mobility as well. One of the risks of orthodontic treatment, as a result of inadequate access for cleaning, includes gingival inflammation.[19] 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 2-year course of orthodontic treatment. This does not usually cause problems as it is so 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[19]. Another risk of orthodontic treatment that can lead to an increase in mobility is root resoption. 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

·     Pippette shaped roots

·     Iatrogenic: use of excessive forces during orthodontic treatment [19]


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.[20]

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.[20] 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.[21]


This is the procedure of increasing resistance of tooth to an applied force by fixing it to a neighbouring tooth/ 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. 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.  [20] A dental splint works by evening out pressure across a patients 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 mouthguard covers both gums and teeth to prevent injury and absorb shock from falls or blows.[20]

Types of splints


  • Resin by itself
  • Resin with flexible arch of nylon or metal wire
  • Orthodontic brackets with malleable arch
  • Vestibular arches or bars

Types (Classified by flexibility)

  • Flexible
  • Semi-rigid
  • Rigid

The use of each type is based on the level of tooth mobility. In general, non-rigid immobilization is preferred as it is passive, atraumatic and flexible which allows a certain degree of movement and thus advocates a functional re-arrangement of the periodontal ligament fibers, and reduces the risk of external resorption and ankyloses.

However, in terms of a high mobility grade such as when there are cases of bone plate fracture and late replantation, a rigid splint might be needed.

Flexible splints are usually made out of composite resin and nylon thread.

Semi rigid splints are usually made with composite resin and orthotondic wire/nylon thread.

Rigid splints are made with composite and rigid wires or Erinch bars and orthodontic appliances.

The variations in these splints that are made out of similar materials are mainly the diameters of the wires and the weight of the threads; more flexible splints are made of wires that are of lesser diameter while more rigid splints are made of wires with a larger diameter, likewise for the threads. In addition, the wires could also be twisted in a mesh like way to make it more rigid.[22]

Two Types of Splinting:

1.   Temporary

  • Extra-coronal splints which are attached ot enamel of several teeth
  • Intra-coronal splints which are placed into a small channel within the tooth and bonded or cemented into place

2.     Permanent of fixed splinting

  • Loose teeth are crowned and fused or joined together[23]


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