shirin saravani oral and dental disease research center, department of oral and maxillofacial pathology, faculty of dentistry, zahedan university of medical sciences, zahedan, ir iran tahereh nosrat zehi oral and dental disease research center, department of oral medicine, faculty of dentistry, zahedan university of medical sciences, zahedan, ir iran hamideh kadeh oral and dental disease research center, department of oral and maxillofacial pathology, faculty of dentistry, zahedan university of medical sciences, zahedan, ir iran; oral and dental disease research center, department of oral and maxillofacial pathology, faculty of dentistry, zahedan university of medical sciences, zahedan, ir iran. tel: +98-543341400, fax: +98-5433414003 sarvar mir zabol university of medical sciences, zabol, ir iran