Macrodontia in guinea pigs (Cavia porcellus)–Radiological findings and localization in 131 patients

Guinea pigs with dental disease usually present with nonspecific signs such as reduced food intake, difficulty eating and poor general condition. It is assumed that deficient dental attrition is the cause for overlong teeth. Giant teeth, or Macrodonts, have been mentioned as an occasionally occurring pathology.Guinea pigs with clinically and radiologically confirmed dental disease presented between 2011 and 2014 and with complete sets of radiographs of the skull (laterolateral, dorsoventral, oblique and isolated views of the mandible and maxilla) were included in this retrospective study (n = 131). Every tooth was radiologically assessed and documented as changed, if an alteration in tooth width, tooth structure, periodontal ligament space, alveolar bone lamina dura and, in the incisors, pulp cavity was present. Special focus was placed on macrodonts and their additional alterations besides increase in width.The majority (89% = 116/131) of all guinea pigs had at least one macrodont; more than half (58% = 246/422) of all abnormal teeth were macrodonts. In total, 246 teeth (54 incisors, 192 cheek teeth) were diagnosed as macrodonts by means of radiography based on the presence of tooth expansion. Mandibular incisors were much more often affected by macrodontia (87%, 47/54). Furthermore, 91% (175/192) of cheek teeth macrodonts were found in the last two tooth positions. In the present study 97% of all macrodonts (238/246) showed both expansion and structural loss. Alterations to the periodontal ligament space were found in 76% (118/246) of macrodonts. The lamina dura of alveolar bone was changed in 46% (113/246) of cases. Abnormalities of the pulp cavity were present in 80% (43/54) of incisor macrodonts.In conclusion, macrodonts occur much more often than previously documented and present a common diagnostic finding in guinea pigs with dental disease. Macrodontia is radiologically characterised by expansion of the tooth and structural loss.