Symphyseal Separation in a Cat

In man we have a complete bone fusion called synostosis, however in cats and dogs this union is a fibrous union or syncondrosis that allows a certain degree of mobility.

If in humans we can use the term fracture to define this symphyseal dis-union, in cats and dogs is called separation.

Our case is a female cat, European Short Hair, 14 years of age, weighing 3 kg, which as a consequence of a car accident suffered multiple traumata. After performing a digital X-ray of the skull in ventro-dorsal and oblique lateral incidence we could see the symphyseal separation marked with an arrow in Fig. 1.

We could also see a fractured canine tooth in the left maxilla as well as a laceration of the upper lip. After patient stabilization and pre-operative blood liver and kidney parameter evaluation for the safety of the anesthesia we performed the preanesthesia using Valium, induced using Propofol and maintained the inhalation narcosis using Isofluran (after proper intubation).

We proceeded with the extraction of the crown and root rest followed by the suture of the postextractional alveolus with a resorbable multifilament Vycril 4.0 in a single interrupted pattern. The 2 halves of the mandible were displaced with about 1cm.

The stabilization methods using surgical wire 0,4 mm (Fig. 2 white arrow) was necessary but not enough because with could have a postoperative luxation around the cerclage due to circumferential forces and as a consequence the destabilization of the symphyseal separation..

As secondary stabilization method we used a parapulpar pin and self curing composite bridge. After insertion of the pins (Whaledent-Kit) in the mandibular canine teeth (Fig. 2, red arrows) we applied a thin layer of orthophosphoric acid for 30 seconds in order to etch the surface of the enamel and improve the adhesion as well as to increase the contact surface between composite and enamel.

In Fig.3 we can see the final stabilization of the symphyseal separation by using an applicator gun for the composite between the 2 mandibular canines and covering also the surgical wire knot to prevent injury of the oral and labial soft tissue. We proceeded than in modeling the composite bridge to assure a normal occlusion and mastication. 

After only 14 days postoperative the stabilization was successful and the normal occlusion achieved (Fig. 4). After a light sedation (short procedure) we removed the composite bridge using a high-speed turbine with a round hard metal burr and orthodontic pliers and the parapular pins by unscrewing with pliers.

The orifices that resulted from the removal of the pins were obturated using light curing calcium hydroxide cement followed by a thorough polishing. The final image is seen in Fig. 5. We can have a transient temporo-mandibular anchylosis or just a temporary joint pain as a consequence of immobilization, but this should recede after a short NSAID therapy.

Camil Stoian, Dr. med. dent., Dr. med. vet., PhD
Diplomate of the European Veterinary Dental College

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