The study of gray-scale value correlated with interproximal caries lesion progression by digital intraoral bitewing radiographs

Abstract

Grayscale value is an adjunct for the caries detection in some dental radiographs, due to its distinguishability of initial proximal carious lesion. This study aims to correlate the gray-scale value of digital intraoral bitewing radiographs with progression level of carious lesions. The sixty samples were recruited from orthodontic patients. Sound, non-restored human premolars containing no restorative material and extracted for an orthodontic purpose were used in this study. Teeth with carious lesions no farther than middle one third of dentin on the proximal side were served as experimental teeth, while teeth without lesion were served as controls. Before extraction premolar tooth, patients fulfilling the inclusion criteria were allocated individually to take the radiographs under a standard bitewing condition by one examiner, the mean grayscale values were calculated. Using a hard tissue macrotome, ground sections, 1 mm thick, were serially and mesio-distally cut in a parallel direction to each anatomical crown’s long axis and observed with a stereomicroscope. Intra-and inter-observer agreements were assessed with a Kappa statistic. Statistical scores and histological gold standard indicated the diagnostic ability. A Simple linear regression test was a statistical method that performs to summarize and study relationships between the size of approximal carious lesion and mean grayscale value. And the result presented a significant relationship between the size of approximal carious lesion and the mean grayscale value. This indicated that 75.1% of the size of approximal carious lesion can be explained by that mean grayscale value with a 0.05 significant level. This is quite high so predictions from the regression equation are reliable. So that, it is possible to define a standard mean grayscale value for the detection of an initial caries in the future study.

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