THE EFFECT OF SUBGINGIVAL CALCULUS ON THE VALIDITY OF CLINICAL PROBING MEASUREMENTS

Objectives: The aims of this study were to assess the validity of the WHO 621 probe for the detection of subgingival calculus and to assess the effect of subgingival calculus on the measurement of probing pocke t depths and clinical attachment levels. Methods: Teeth used in the st udy were designated for extraction under local analgesia. Prior to ext raction the clinical detection of subgingival calculus was made with a WHO 621 probe. Probing pocket depths and clinical attachment levels w ere measured. The location and direction of the gingival margin and pr obing measurements were marked on the teeth with a fine, sterile penci l and following extraction, permanent reference grooves were cut with a fine, tapered diamond bur. The extracted teeth were stained with Gom ori's stain and examined for the presence of calculus, and the pocket depths and attachment levels were measured using a stereomicroscope. R esults: There was an 80% agreement between the clinical and laboratory detection of subgingival calculus. There was no systematic difference between clinical and histopathological measurements when calculus was present or absent (P > 0.05). Analysis of variance indicated a random error effect due to the presence of subgingival calculus. Conclusion: This study has demonstrated the validity of the WHO 621 probe in dete cting subgingival calculus and has shown that subgingival calculus cou ld be a source of error in the measurement of probing depths and clini cal attachment levels. Copyright (C) 1996 Elsevier Science Ltd.