3. stain over more than 2/3 of the surface Supragingival calculus on the lingual surfaces of the six mandibular anterior teeth will be scored using the Volpe-Manhold calculus index (CI) (Volpe et al. 1965). The supragingival calculus in three defined planes on the lingual surface of each tooth will be measured using a periodontal probe. The measurements will be added and a mean subject score will be calculated.