Tori in a Malaysian population: Morphological and ethnic variations

AIM: Tori are nonneoplastic self-limiting, bony exostosis that are commonly called torus palatinus (TP) when seen on the hard palate and termed torus mandibularis (TM) when seen on the lingual surface of the mandible. These lesions have long been known to anthropologists and have mostly been identified incidentally during routine dental examinations. The prevalence of tori varies in different populations from 0.0% to 66% for TP and between 0.1% and 63.4% for TM. The exact etiology is still unclear, but the most accepted theory today is 30% attributed to genetics and 70% to environmental factors. Hence, the aim of this study was to determine the prevalence of tori and study their morphology among various ethnic groups of a Malaysian population. MATERIALS AND METHODS: A ross-sectional study was conducted involving the screening of patients that reported to the oral medicine clinics over a 2-year period. Age, gender, ethnicity, morphological variations in shape and size, number, and location of tori were recorded in all positive cases. RESULTS: Fourteen percent of individuals (n = 624) among the total 4443 who were screened were found to have either palatine tori, mandibular tori, or both. The prevalence of PT and MT was 10.8% and 0.9%, respectively. Tori were found in people in the age range of 5–85 years, with the maximum in the age range of 20–29 years (24.7%). The male-to-female ratio for PT and MT was 1:1.4 and 1:0.68, respectively. The morphologic shapes of palatine tori that were observed were flat (10%), spindle (10%), linear (15%), and nodular (59%) with up to six lobules. Mandibular tori were located either unilaterally or bilaterally; they were nodular in shape (89%) and/or band like (15%), with the band-like shape being described for the first time. Size variations ranging from 0.5 to 5 cm were observed. CONCLUSION: The relatively high prevalence of tori among major ethnic groups of this region supports the probable hypothesis of the role of environmental factors. A wide variation in the morphology was also noted, along with a new morphologic variant of band-like TM, which may be due to the influence of diet or an unknown environmental factor.