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Continued from page 77. Answer It is exceedingly common for teeth to be absent in the dental arcades of veterinary patients. If the tooth is not seen above the gumline, do not assume it is truly absent or previously extracted. Possible etiologies for "missing" teeth include:1 1. Congenitally missing:2 This is generally considered to be a genetic problem, but can also occur secondary to significant in utero or neonatal issues. Congenitally missing teeth are common in small, toy, and brachycephalic breeds,3 with a predisposition in the Chinese Crested and Mexican hairless breeds.1 Teeth most typically affected include premolars, maxillary second and mandibular third molars, and incisors. No specific therapy is necessary. 2. Previously exfoliated or extracted: While rare in juvenile patients, this cause is common in mature to geriatric animals. Exfoliation (ie, the tooth has fallen out "on its own") typically results from periodontal disease, but may also be trauma related. In older animals, extraction is a more likely cause. In these cases, radiographs will usually reveal evidence of a healing alveolus. Again, no specific therapy is necessary. 3. Fracture below the gingival margin: This condition is also rare in the juvenile patient, but common in adults. Subgingival tooth fractures may occur as a result of an incomplete extraction attempt, and retained roots are actually far more common than thought.4 Dental radiographs can confirm retained roots and potential infectious lesions. Surgical extraction is generally recommended to alleviate pain and endodontic infection. 4. Impacted or embedded: These teeth may be malformed or normal, but do not erupt into the dentition because they are blocked by a structure, such as bone or tooth (deciduous or permanent) or, most commonly, by an area of thick and firm gingiva called an operculum. This condition is most common in the first and second premolars of brachycephalic breeds. It is critical to note that the first two causes for "missing" teeth require no therapy, because the teeth are truly absent. However, the remaining two causes can be associated with significant pathology. Therefore, all "missing" teeth should be radiographed to determine whether the cause is true absence versus subgingival pathology.5 Question 2 Figure 2 is a dental radiograph of the area of the absent mandibular first premolar. Based on the physical examination findings and radiograph, what is your diagnosis and treatment plan? Turn to page 80 for the correct answers regarding diagnosis and treatment. May/June 2013 Today's Veterinary Practice 79 Case of the Missing Tooth DENTAL DIAGNOSIS |