An instrument to quantify dental calculus deposits

An instrument to quantify subgingival dental calculus was developed and validated in human subjects. The device uses a miniature single-axis strain gauge accelerometer which detects and analyzes vibrations in a metal probe as its tip traverses the rough calculus deposits, and calculates a heuristic metric, the gated envelope energy ratio (GEER), intended to relate vibration signatures to the tactile sensation of calculus. In experiments on 14 patients, receiver operator characteristics relating GEER to an arbitrary, subjective, ordinal calculus score were used to assign appropriate breakpoint levels of GEER to calculus score. For the critical threshold separating scores of 0 (absence of calculus) from 1 (minimal calculus), a value GEER=2.25 yielded sensitivity and specificity of 71% and 75% respectively.