A severe case of scissors beak can
prevent the prehension of food and will cause abnormal wear on both sides
of the gnathotheca. The gnathotheca on the side of the deviation will wear
excessively, and the gnathotheca on the contralateral side will grow unabated.
. . .
In theory, any slight injury to the cere or germinal beds during early development could cause scissors beak (Figure 42.33).
... Keratin normally migrates rostrally along the surface of the beak and laterally from the vascular bed. Any change in the rate of keratin migration between these two sites, any change in the premaxilla that changes the orientation of the tip, or a malformation of the frontal bone could cause the beak to deviate laterally. Correction procedures are designed to change the forces that direct the anterior growth of the rhinotheca (Figure 42.34).
Redirected growth is achieved by applying a prosthesis to the lower beak on the affected side or by placing pins in the calvarium and using rubber bands to apply pressure to the tip of the beak (similar to orthodontic techniques used in humans).
. . .
The prosthetic device must be sufficiently anchored to the lower beak to prevent normal beak occlusion from dislocating the prosthesis. The keratin of the gnathotheca on the affected side is grooved with a Dremel tool. The grooves should be deep enough to increase the surface area for prosthetic attachment but should not be so deep as to induce hemorrhage. The scored gnathotheca is cleaned and disinfected, and a light coat of cyanomethacrylate is applied to the area and allowed to dry. Stainless steel or nylon dental screen mesh is molded to the gnathotheca. The mesh should be extended to create a ramp that redirects the beak tip to the midline with each bite. The ramp is covered with cyanoacrylate and smoothed with a Dremel tool. When the defect is corrected, the implant is removed.
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