Today's Veterinary Practice provides comprehensive information to keep every small animal practitioner up to date on companion animal medicine and surgery as well as practice building and management.
Issue link: http://todaysveterinarypractice.epubxp.com/i/321264
May/June 2014 Today's Veterinary Practice 101 PracTical DenTisTry | Disorders of Dental Hard Tissues in Dogs tvpjournal.com tooth has responded to the insult and is vital. However, radiographs are not very specific for diagnosing infected teeth 22 because: • 30% to 50% of the bone must be lost before it is appreciated radiographi- cally 23 • The endodontic system changes very gradually in older pets. 5 A 2001 study by Hale demonstrated that only 40% of intrinsically stained teeth had radiographic signs of end- odontic disease. 24 However, when physically examined, 92.7% were non- vital and infected. In our experience (over 1000 cases), all discolored teeth have been nonvital and infected. Treatment Options 1,2 Discolored teeth (with the exceptions noted earlier) are generally irrevers- ibly inflamed or necrotic. Once the endodontic system becomes nonvital and/or infected, the tooth must be removed. There are 2 main options for removal. Root canal therapy is the treatment of choice for larger teeth, such as ca- nines and carnassial teeth (Figure 14). Extraction is a viable alternative for small teeth, such as incisors and pre- molars; however, root canal therapy is also indicated if the client wishes to save the tooth. ABRASION/ATTRITION 1 These lesions are similar to uncom- plicated crown fractures; however, they result from long-term wearing of the tooth as opposed to a 1-time traumatic event. Both of these lesions are created by chronic contact with a hard object. • Abrasion is caused by a tooth wear- ing against something foreign. • Attrition is caused by tooth-on- tooth contact. Attrition is caused by a malocclu- sion in which the opposing teeth are in contact, which may be due to: • A level bite —a mild class III maloc- clusion (undershot) and most com- mon cause (Figure 15) 25 • Maxillary third incisors creating attrition on the mandibular canines (Figure 16) • Improper reduction of a maxillo- facial fracture. Abrasion can be caused by many different objects but, in general, is due to very aggressive chewing, which is more common in large breed dogs. • Chronic chewing on toys , such as tennis balls, wears down the canines and premolars (Figure 17). • Chronic chewing on the skin due to allergic dermatologic disease typically wears down the canines and incisors, often to the gum line (Figure 18). Figure 14. Thirteen-month recheck radiograph of patient in Figure 13; root canal success is evidenced by resolution of the periapical rarefaction (green arrows), and note the slight endodontic overfill (blue arrows). A B Figure 15. Significant dental attrition to incisor teeth caused by a slight class III (level) bite. Figure 16. Significant class III maloc- clusion in a boxer (normal for breed). The significant jaw length discrepan- cy (A) has created contact between the maxillary third incisor and man- dibular canine, resulting in significant attrition on the mesiolingual aspect of the mandibular canines (B). This tooth can be restored, but only following extraction, or significant crown reduc- tion of the offending incisor. Figure 18. Severe abrasion to the mandibular incisors and canines; note that teeth are worn down to the gumline and both canines, as well as 402 and 303, have direct pulp exposure and are nonvital. A B Figure 17. Significant abrasion (A) to left maxillary canine and premolars due to constant tennis ball chewing; note the exposed and necrotic canine tooth pulp despite reparative (tertiary) dentin on the premolars. Significant abrasion (B) to right canines of a dog with a tennis ball habit; the teeth are severely worn, but the root canal is not exposed. TVP_2014_0506_PD_HardTissue-Periodontal.indd 101 5/23/2014 6:35:57 PM