12.7.5 Pulp canal obliteration
There is progressive hard tissue formation within the pulp cavity leading to a gradual
narrowing of the pulp chamber and root canal and partial or total obliteration. There is
a reduced response to vitality testing and the crown appears slightly yellow/opaque.
The exact initiating factor which produces this response from the odontoblasts is
unknown. It is more common in immature teeth and in luxation injuries rather than in
concussion and subluxation injuries. Although radiographs may suggest complete
calcification there is usually a minute strand of pulpal tissue remaining. Pulpal
obliteration has been described as 'natures own root filling'and although the late
development of necrosis and infection in the thin thread of pulpal tissue in the
sclerosed canal has been reported, it is less common than the endodontic
complications that would be necessary to treat it. The obturation of an 'obliterating'
canal is not justification for pre-eruptive root canal treatment in the absence of signs
of pulp breakdown.
12.7.6 Injuries to the supporting bone
The extent and position of the alveolar fracture should be verified clinically and
radiographically. If there is displacement of the teeth to the extent that their apices
have risen up and are now positioned over the labial or lingual/palatal alveolar plates
('apical lock') then they will require extruding first to free the apices prior to
repositioning. The segment of alveolus with teeth requires only 3-4 weeks of rigid
splintage (composite-wire type) with two abutment teeth either side of the fracture,
together with antibiotics, chlorhexidine, soft diet, and tetanus prophylaxis check (770HFig.
12.49 (a)-(c)). Pulpal survival is more likely if repositioning occurs within 1 h of the
injury. Root resorption is rare.
771H
Fig. 12.49 (a) Dentoalveolar fracture of the lower labial segment. (b) Fracture
reduced into the correct occlusion. (c) Splint in situ prior to removal.