Iatrogenic malocclusion

30 Iatrogenic malocclusion




INITIAL PRESENTATION


A dog unable to close his mouth, with atrophy of the muscles of mastication on the left side of the face.



PATIENT DETAILS


A 5-year-old, male, springer spaniel.



CASE HISTORY


The dog was referred for management of complications to jaw fracture healing. Case history was not supplied. The owner reported that the dog had been involved in a road traffic accident 6 weeks earlier. The mandible had fractured, as had multiple teeth. The mandibular fracture had been stabilized using double figure-of-eight wires around the lower canines (wires in place but loose) and some teeth had been extracted. Further extractions had been performed 3 weeks prior to referral. The dog had been unable to close his mouth since the accident (6 weeks ago) and the owner had noticed that the muscles on the left side of the face (above eye) were undergoing atrophy. The dog was eating well but selecting soft food rather than kibbles.



ORAL EXAMINATION – CONSCIOUS


This was a boisterous dog that did not cooperate sufficiently for thorough oral examination, but findings on cursory examination were as follows:


• Continuous drooling

• Normal jaw opening, but unable to fully close mouth (Figs 30.1, 30.2 and 30.3)

• Lower jaw deviating to the right (Figs 30.1, 30.2 and 30.3)

• Incisors in reverse scissor occlusion (Figs 30.1, 30.2 and 30.3)

• Tooth 404 positioned laterally to 103 (Fig. 30.2)

• Tooth 304 positioned medially to 203 (Fig. 30.3)

• Missing teeth (Fig. 30.1)

• Fractured teeth (Fig. 30.1)

• Marked muscle wastage of muscles of mastication (temporal, masseter and pterygoid) on the left side.

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Figure 30.1 Head-on photograph of the rostral occlusion. The mandible is deviated to the right and the dog is unable to close his mouth because of the iatrogenic (mandibular fracture stabilized without considering occlusion) malocclusion; 404 is lateral to 103 and 304 is trapped medial to 203. There is also reverse scissor occlusion of incisors, which may have been present prior to jaw fracture. Note also the missing (303, 401, 403) and fractured teeth (202, 402).


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Figure 30.2 Right lateral photograph of the rostral occlusion. The deviation of the mandible to the right and the traumatic occlusion of the right lower canine (404 occluding with the lateral aspect of 103) is evident, as is the reverse scissor occlusion of the incisors.


image

Figure 30.3 Left lateral photograph of the rostral occlusion. The deviation of the mandible to the right and the traumatic occlusion of the left lower canine (304 is occluding with the palatal aspect of 203) providing mechanical obstruction to full mouth closure is obvious, as is the reverse scissor occlusion of the incisors.



ORAL EXAMINATION – UNDER GENERAL ANAESTHETIC


While occlusion is best assessed in the conscious animal, in cases that are not amenable to conscious occlusal evaluation, it needs to be performed under general anaesthesia. The tongue needs to be folded caudally during the evaluation so as not to interfere with normal jaw closure. Pharyngotomy intubation rather than orotracheal intubation is useful when occlusal evaluation is required.


A thorough oral and dental examination, including investigating periodontal parameters, was performed. All findings were noted on the dental record sheet.


In summary, examination under general anaesthesia identified the following:


1. The mandibular fracture had healed. The jaw was stable and there was a palpable callus at the ventral border of the left and right mandible level with apices of canine teeth.

2. Jaw opening was normal.

3. Full closure of the mouth was not possible due to the mechanical obstruction from the malocclusion (Figs 30.1, 30.2 and 30.3):
• Tooth 404 was positioned laterally to 103

• Tooth 304 was positioned medially to 203.

4. There was no swelling, abnormal movement or crepitus from the temporomandibular joint (TMJ) on either opening or partial closure of the jaws. When evaluating the TMJ, it is useful to place the animal in dorsal recumbency and manipulate jaw opening, closure and lateral movement while a second person holds the head and upper jaw in a fixed position. The tongue needs to be folded caudally to avoid interference with jaw closure.

5. There was marked atrophy of the muscles of mastication on the left-hand side.

6. There were complicated crown fractures (CCF) of 202 and 402 (Fig. 30.1).

7. There was an uncomplicated crown fracture (UCF) of 204.

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Sep 3, 2016 | Posted by in SMALL ANIMAL | Comments Off on Iatrogenic malocclusion
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