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Tooth Response to Traumatic Injuries

The tooth will respond differently to different traumatic injuries. This depends on various factors viz. type of impact on tooth, vascularity of the canals, condition of periradicular structures, alignment of teeth etc.

Pulpal Response

Favourable
Pulp response is favourable if it recovers & returns to it’s normal state. Pulp tissue could also fibrose or these may be pulp canal obliteration (PCO), which could be partial or complete.

Unfavourable

Pulp response to injury/trauma could lead to pulp necrosis or infection of the pulp space. It could lead to internal resorption of the tooth, which could be a surface resorption, inflamatory resorption or replacement resorption.

•Peri-radicular Responses to Trauma

Favourable

A favourable response would mean recovery and return to a normal state, fibrous healing or a transient apical breakdown.

Unfavourable

Unfavourable response would lead to cessation of root development, disturbances to root development or bone resorption which would be marginal (crestal), apical,lateral depending on the position with respect to the tooth surface.There could be gingival recession or external root resorption which can be categorized as surface, inflammatory and replacement resorption.

Resorption as a Sequela to Traumatic Injuries

Resorption is the most frequent sequela to luxation injuries; three different types of resorption have been identified:

1) Surface,

2) Inflammatory, and

3) Replacement (ankylotic) resorption

Surface resorption: Small superficial cavities in cementum and outermost dentin. This type is not visible on radiographs and is usually repaired by new cementum. It may be transitory or progressive. The former leads to repair, the latter to further resorption

i) Inflammatory Resorption

Radiographically seen as a bowl-shaped resorptive area of the root and associated with adjacent bony radiolucencies. It involves both tooth structure and adjacent bone.Radiographically, there is apparent tooth loss along with adjacent bony destruction.Root canal therapy can be expected to arrest inflammatory resorption that involves replanted teeth; the resorption can be prevented by judicious timing of the root canal therapy.

ii) Replacement Resorption: External Replacement Resorption

Resorption of the root surface and its substitution by bone, resulting in ankylosis. This is a frequent sequela to replantation. As tooth structure is resorbed, it is replaced with bone that fuses to the tooth structure, thereby producing ankylosis.

iii) Invasive External Root Resorption Appears

• Usually many years after trauma

•Radiolucency — poorly defined margins

•Sub-gingival — external origin

•Resembles caries or internal resorption

•Very vascular — bleeds on probing

•Resorption is by invasive tissue and not inflammatory tissue

Factors Affecting Resorption
The following factors determine the rate of resorption

a) Extra-alveolar time — Greater the time greater the chances of resorption

b) Storage conditions — Storage in appropriate media delays resorption

c) Damage during avulsion — Loss of supporting periodontal fibers on the root or in the socket will lead to resorption. Mechanical damage can not be controlled.

d) Replant procedure — During replant procedure minimise trauma. An atraumatic procedure provides the best results.

e) Splinting- Physiologic splinting provides greatest chances for success.

f) Splinting

i) Flexible splint:

1) 7 - 10 days only

2) If NO root or bone fractures

3) Allows “functional” healing of periodontal ligament

4) Reduces ankylosis and replacement resorption

ii) Rigid splint - ONLY if:

1) Associated with bone fracture will take 6 weeks

2) Or if root fracture will take about 3 months

g) Endodontic treatment at the appropriate time with medicaments as required will delay resorption.

Treatment of Resorption

In case of progressive resorption, any form of treatment does not help to arrest the resorption. Eventually the tooth has to be extracted so the treatment is directed to prevent or minimise the occurance of this type of resorption.In case of a transient resorption, treatment is not required and it stops by itself. It is difficult to access the difference between the progressive and transient type of resorption.

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