Clinical bone densitometric evaluation of the mandible in removable denture wearers dependent on the morphology of the mandibular cortex

Abstract

Statement of problem Wide normal variations have been found in the structure and density of the human skeleton, as well as of the mandible. Purpose The objective of this study was to determine whether the mandibular bone mineral density is correlated with the classification of the structure of the inferior cortex on panoramic radiographs in complete and removable partial denture wearers. Material and methods The mandibular cortical index of 136 randomly selected complete and removable partial denture wearers was evaluated via panoramic radiographs. The criteria for the mandibular cortical index were as follow: category 1, sharp endosteal margin of the inferior cortex; category 2, semilunar defects; and category 3, thick cortical residues on endosteal margin. Forty male patients (mean age 72.7; range 56 to 84 years) and 96 female patients (mean age 69.7; range 48 to 86 years) participated. With a copper stepwedge and DenEx 2001 computer program, the mandibular bone mineral density was investigated densitometrically on dental panoramic radiographs. Four experienced observers and 6 general dental practitioners made the observations on all panoramic radiographs. All bone mineral density values were expressed in equivalents of the actual stepwedge thickness. An independent t test (α = .05) was used. Results The severity of changes in the mandibular cortex was significantly related to all measured mandibular bone mineral density values ( t test: P<.01). Mandibular cortical index category 3 had significantly lower bone mineral density values in all measured regions of interest. Interobserver and intraobserver agreement in mandibular cortical index assessment was excellent. Conclusion Patients having lower bone mineral density values in the mandible have much more porous cortical layer of the inferior border of the mandible.