Relationship between bacterial infection and evaluation using a laser fluorescence device, DIAGNOdent

Abstract

The aim of this in vitro study was to investigate the relationship between bacterial infections in carious dentin when detected by two different methods -- polymerase chain reaction (PCR), and a laser fluorescence device, DIAGNOdent. Dentin was removed every 300 micro m in the direction of the pulp chamber in 10 extracted molars with occlusal dentin caries and 3 extracted sound molars. Dentin surfaces were evaluated using DIAGNOdent, and dentinal tissue samples were removed by using a round bur before and after each removal. Bacterial DNA in the dentinal tissues was detected by PCR, using primers based on the nucleotide sequence of a conserved region of the 16S rDNA, and yielded a PCR product of 466 bp. The rates of bacterial detection increased as the DIAGNOdent values increased. In the 10 specimens, the lowest DIAGNOdent value at which bacteria were detected was 15.6; at DIAGNOdent values below 15.6, no bacteria were detected. The results of a receiver operating characteristic (ROC) curve for the DIAGNOdent values showed that the area under the ROC curve was 0.91. This study clarified the relationship between the DIAGNOdent values of dentin caries and the rates of bacterial detection.

Validity of a portable microhardness testing system (Cariotester) for diagnosis of progression in active caries lesions

“…DIAGNOdent measures fluorescence from caries lesions that is thought to originate from bacterial metabolites 14) , and this fluorescence closely correlates with estimates of bacterial prevalence in these lesions 15,16) . DIAGNOdent is thus considered a gold standard for measuring the progression of caries.…”

“…In our previous study 15) , we found that bacteria were not detectable by PCR when DIAGNOdent gave values of <15.6 in active caries lesions. Substituting this value into the regression formula derived in this study (HK=0.419+238.342/D), this equates to a limit of bacterial detection of HK=15.7.…”

“…This cavity preparation device gives three-dimensional control of a contra-angle handpiece with a bur with an accuracy of three micrometers, enabling great precision in the amount of dentin removed 5,6,15,16) . Carious and sound dentin surfaces were stained with the caries detector dye for 10 s, rinsed with distilled water, and air-dried with a three-way syringe 7,8) .…”

“…The additional calibration of subtracting 'normal' dentin or enamel fluorescence values (obtained from sound tissue adjacent to the caries) from those of test dentinal surfaces was not carried out since the variability in the fluorescence of the sound coronal dentin in our carious samples was too high 16,18) . The average of the 10 maximal values (DIAGNOdent values) from each dentinal surface was calculated 15,16,19) . After DIAGNOdent assessments, the HK of the carious and sound dentin surfaces (the same surfaces as assessed with DIAGNOdent) was measured three times with a Cariotester portable microhardness testing system (Fig.…”

“…In addition, our previous study 15,16) found that DIAGNOdent evaluation in both active and arrested caries lesions was closely related to the prevalence of bacteria in those same lesions. Therefore, DIAGNOdent evaluation has potential as a tool for quantitatively evaluating the degree of caries progression in the lesion and its bacterial infection status.…”