Figure 1A (above): Preoperative dental radiograph of the mandibular canines and incisors of a nine-year-old cat. Due to the minimal amount of bone between the symphysis and the distolingual portion of the canine roots, this radiograph should raise a red flag of higher-than-normal risk of iatrogenic mandibular fracture.Figure 1B (below): Iatrogenic mandibular fracture in the same cat along the lingual aspect of tooth #304. In last month's Dental Pearls column, we looked at iatrogenic mandibular fractures, many of which occur during attempts to extract teeth in cats. With this in mind, I thought we’d devote the next two columns to a discussion of feline extraction techniques. One of the phrases that sticks with me from my time in veterinary school is that “cats are not small dogs.” I’d love to know who was the first to utter this bit of concise brilliance. This phrase has many applications, from drug pharmacokinetics to anatomy. Further, it can be applied to oral surgery necessary to extract a firmly rooted tooth in the cat. Below are some superpowers that will help you when faced with your next cat extraction. Know this: Cat extractions are more about finesse and less about force. Too much of it can result in undesirable consequences (Figure 1). Superpower #1: X-ray vision One thing that makes feline extractions different than those in the canine species is the high prevalence of tooth resorption in cats. Feline extractions should not be attempted without the ability to perform preoperative intraoral radiographs. If you don’t have dental radiography, you can’t determine if there is a tooth root still present requiring extraction. Tooth resorption may occur in varied manifestations, and the approach to treatment depends on the radiographic appearance of the affected tooth. This pathologic process in cats is commonly due to an external resorption starting on the root surface, later resulting in a visible area of focal tooth resorption where the crown meets the root, often referred to as Type 1 resorption. Teeth affected by Type 1 resorption require extraction, which can be challenging in these instances, since in some areas, the tooth may be “spot welded” to the surrounding alveolar bone due to loss of normal periodontal ligament structure. Type 2 external resorption is seen on radiographs as root replacement resorption, in which the radiographic density of the root is much less than that of an unaffected root, approximating the density of bone rather than normally dense root structure. This is where radiographs are so important—if you don’t have dental radiography, you won’t know if there are truly roots still present requiring removal. In some cases, Type 2 root resorption can be so severe that the roots of a tooth are no longer present. I’ve seen cases of iatrogenic mandibular fractures that occurred in cats when practitioners tried to extract roots that were no longer there. Without dental radiography, these practitioners were unaware the normal root structure was replaced by a bone-cementum replacement material due to the resorption process. In these cases, a technique referred to as “crown amputation” or “coronectomy” can be performed. Coronectomy is easier than an extraction, which can make it prone to abuse. Use dental radiographs and clinical appearance of the tooth’s hard tissue to determine whether coronectomy is an acceptable option. Radiographic features that indicate whether coronectomy is appropriate are: radiographic density of the root structure approximating that of bone rather than normal root; no radiographic evidence of an endodontic canal within the resorbing root; no evidence of a pathologic periapical lucency; and lack of a normal periodontal ligament space around the tooth root. Clinically, unless the root looks completely resorbed on dental radiographs, I err on the side of raising a flap and removing the lateral wall of bone to expose the root and visualize what the root structure of a tooth looks like. Unresorbed root structure appears glassy tan/yellow, rather than a pinkish-white color seen in roots that have been replaced by bone. Additionally, a fully resorbed root shows no signs of pinpoint bleeding from a central endodontic system when assessed on the cross-section of where the root meets the crown. If all these criteria are met, both clinically and radiographically, coronectomy may be performed. Type 3 root resorption is the presence of Types 1 and 2 resorption in the same tooth. For example, Type 3 resorption would be seen in a mandibular third premolar tooth where the mesial root shows Type 1 resorption and the distal root shows complete root replacement resorption (Type 2). Each root is treated differently depending on its radiographic appearance. In the example above, the mesial root would need to be extracted in its entirety, whereas the distal root may be a candidate for coronectomy. Superpower #2: High-speed dental handpiece to the rescue When removing firmly rooted teeth, I start by incising the gingival attachments on the tooth’s buccal surface and perform releasing incisions to raise a mucoperiosteal flap from the lateral surface of the root(s). This is easier said than done in cats, whose gingiva and mucosa are very thin and prone to perforation. Use of the small end of an EX-9 periosteal elevator helps to finesse the soft tissue off the alveolar bone without trauma. After raising a mucoperiosteal flap, a window of bone is removed over each lateral root that needs to be delivered. I find that in most clinics I visit, the practice has invested thousands of dollars to purchase a high-speed dental unit, but didn’t spend the extra few dollars to have an appropriate assortment of dental burs suitable for feline extractions. For cats, a water-cooled #2 surgical-length round bur is helpful to remove bone over the root, and a 701 bur is helpful to section multi-rooted teeth into single crown-root segments to allow a three-rooted tooth to be extracted as if it were three one-rooted teeth. Another bur that should be in your armamentarium is the ½ surgical-length bur, which is essential for what I call “detail work.” Using this tiny round bur for precision increases the chances of getting the root out in its entirety. Further, it is an essential bur to create a moat around roots that have broken off. Next month, we will continue the discussion with additional tips and tricks to help make the feline extraction process a little less painful for the operator. John Lewis, VMD, FAVD, DAVDC, practices dentistry and oral surgery at Veterinary Dentistry Specialists and is the founder of Silo Academy Education Center, both located in Chadds Ford, Pa.
