Laser Fluorescence Device Research Articles

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

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.

Effects of Drying Time and the Presence of Plaque on the in vitro Performance of Laser Fluorescence in Occlusal Caries of Primary Teeth

The diode laser fluorescence device was introduced to diagnose caries lesions in occlusal and smooth surfaces. Despite promising results, much variation has been found in the protocol of utilization. The goal of this study was to evaluate the influence of dental plaque and drying time on the laser fluorescence (DIAGNOdent) performance in occlusal sites of primary molars. For the drying time study, 63 suspected occlusal sites in primary molars were used. The same sites were evaluated in four different conditions: (1) moist teeth, (2) teeth dried for 3 s with a 3-in-1 syringe, (3) teeth dried for 15 s, and (4) dehydrated teeth. For the plaque experiment, we selected 28 occlusal sites. After the baseline laser fluorescence readings, plaque collected from children was placed on the suspected site. New laser fluorescence measurements were performed. For both studies, we compared the laser fluorescence values, as well as sensitivity, specificity, accuracy, and area under ROC curve. For different drying times, the more dehydrated the teeth, the higher the values. Nevertheless, the performance of the method did not change significantly, except for dehydrated teeth. In the presence of plaque, the laser fluorescence values were reduced, and the evaluated parameters were worse than with no plaque. In conclusion, the hydration state of the teeth did not change the results significantly, but the presence of plaque worsened the performance of the laser fluorescence method.

Effect of topical applications of a chlorhexidine/thymol‐containing varnish on fissure caries assessed by laser fluorescence

The aim of this study was to monitor the effect of an antibacterial varnish using the readings of a caries‐detecting device (DIAGNOdent) in fissures of young permanent molars. The material consisted of 32 healthy patients with a mean age of 14.1 years undergoing orthodontic treatment with fixed appliances. The inclusion criteria were presence of one homologous pair of 2nd upper or lower molars with clinically intact occlusal surfaces. A split‐mouth study design was used in which the fissures were treated with either an antibacterial chlorhexidine/thymol‐containing varnish or a placebo varnish every 6th week. The follow‐up period was 42 weeks and laser fluorescence (LF) readings were carried out every 12th week. The mean LF values increased significantly (P < 0.05) after 24, 36, and 48 weeks compared to baseline following the placebo treatments but not after treatment with the active antibacterial varnish. During the study period, micro‐cavities were diagnosed in two test‐treated and five placebo‐treated teeth. In conclusion, the results reinforce previous findings that frequent applications of a chlorhexidine/thymol‐containing dental varnish might have a protective role in fissures of young permanent molars and that this could be monitored with a chair‐side caries detecting LF device.

Clinical Study of the Use of the Laser Fluorescence Device DIAGNOdent for Detection of Occlusal Caries in Children

Diagnosis of non-cavitated occlusal caries is generally considered problematic. The aim of this study was to evaluate the utility of the laser fluorescence device DIAGNOdent as part of routine dental check-ups in children. A total of 613 occlusal surfaces on permanent molars and 436 surfaces on primary molars in children aged 7–8 (n = 55) and 13–14 years (n = 54) were examined visually, using DIAGNOdent and for most 13- to 14-year-olds also using radiographs. The teeth were not cleaned professionally before examination. To provide a gold standard for carious teeth, the depth of the caries lesion was determined in those lesions that were judged visually to need opening by drilling (51 teeth). The higher the visual score, the higher were the mean DIAGNOdent values, but in each visual category the variation among values was large. The presence of a clear sealant did not affect DIAGNOdent measurements. The values for permanent and primary molars differed slightly. For permanent teeth, Youden’s index value was highest (60%) at a cut-off value of 30, which indicates that the overall performance for DIAGNOdent in detecting dentinal caries was best at this point. Using this cut-off, sensitivity was 92% and specificity 69% with visual examination for validation, while sensitivity was 92% and specificity 82% with validation by fissure opening. Of the three methods, radiographic examination was the least accurate. In routine dental check-ups of children, DIAGNOdent appears to be useful as an adjunct to visual examination.

Reliability and validity issues of laser fluorescence measurements in occlusal caries diagnosis

Objectives. Recently, a device for detecting occlusal caries lesions based on laser fluorescence measurements (DIAGNOdent ®) has been introduced. The reliability (reproducibility) and validity of this laser-fluorescence device were investigated. Methods. In the in vitro part of the study, 49 permanent molars were measured by two observers using two DIAGNOdent ® devices. In addition, visual inspection was performed. The teeth were sectioned to measure the actual depth and area of the caries lesions. In the in vivo part of the study, 45 sites at the occlusal surfaces of permanent molar teeth in 13 patients were measured by two observers using two DIAGNOdent ® devices, manufactured in two successive years. Results. The reliability of both DIAGNOdent ® devices expressed in the intraclass correlation coefficient (ICC=0.90 for observer 1, and 0.88 for observer 2) was high, and so was the interobserver reliability (ICC=0.85 for the 1998-device, ICC=0.90 for the 1999-device). The correlation between DIAGNOdent ® measurements and the actual depth of the caries lesions was lower than that of visual inspection by one observer, yet higher than that of a second observer. The specificities of visual inspection (0.94 and 0.88) were higher than those of the DIAGNOdent ® devices, whereas the sensitivities of the DIAGNOdent ® devices (0.93–1.00) exceeded those of visual inspection The validity of the DIAGNOdent ®, expressed as the area under the receiver operating characteristic curve, was not statistically significantly different from that of visual inspection ( P>0.05). The DIAGNOdent ® measurements showed a higher association with the enamel part of the caries lesion than with the dentinal part. Conclusions. The DIAGNOdent ® is suitable for monitoring small caries lesions. Because of the high reproducibility of DIAGNOdent ® devices produced in successive years, a DIAGNOdent ® device may be replaced by a new one. Due to the higher specificity, visual inspection should be preferred to diagnose occlusal caries lesions in populations with a low caries prevalence.

Performance and Reproducibility of a Laser Fluorescence System for Detection of Occlusal Caries in vitro

The diagnosis of occlusal caries at non–cavitated sites remains problematic, especially since clinical visual detection has limited sensitivity. Electrical methods of detection show considerable promise, but specificity is reduced. The aims of this in vitro study were: (1) to assess the validity of a new laser fluorescence device – the DIAGNOdent – (and compare the values with those of a fixed–frequency electrical device); (2) to determine the optimum cut–off points of the new device for different stages of the caries process, and (3) to assess the reproducibility of the new laser device. For validity and determination of optimum cut–off points, 105 extracted teeth with macroscopically intact occlusal surfaces were measured by a single examiner, using both the laser fluorescence device (on both moist and dried teeth) and an Electronic Caries Monitor. The teeth were subsequently examined histologically to determine the specificity, sensitivity and likelihood ratio at the D₂ (caries extending through more than half of the enamel thickness) and D₃ (caries involving dentin) levels. The values obtained for the laser device ranged from 0.72 to 0.87 (specificity), 0.76 to 0.87 (sensitivity) and 3.0 to 5.6 (likelihood ratio). Those for the ECM ranged from 0.64 to 0.78 (specificity), 0.87 to 0.92 (sensitivity) and 2.4 to 4.1 (likelihood ratio). To determine intra– and interexaminer reproducibility of the DIAGNOdent, 11 dentists recorded two different measurements at the same site on a separate set of 83 extracted molar teeth, and these were compared using Cohen’s kappa (at D₂ and D₃ levels) and Spearman’s correlation coefficient. The average intra–examiner kappa scores were 0.88 (D₂) and 0.90 (D₃), with a Spearman correlation of 0.97. For interexaminer reproducibility, the average kappa values were 0.65 (D₂) and 0.73 (D₃), with a Spearman correlation of 0.84. It is concluded that for occlusal caries (1) the new laser device has a higher diagnostic validity than the ECM, and (2) in vitro, measurements using the device are highly reproducible. Thus, the laser device could be a valuable tool for the longitudinal monitoring of caries and for assessing the outcome of preventive interventions.

Catalonian population study of the tetranucleotide repeat loci D3S1358, D8S1179, D18S51 and D19S253.

Allele frequencies for four short tandem repeat loci were determined in a population sample from Catalonia (NE Spain). After denaturing PAGE electrophoresis, 8 alleles were identified for D3S1358 (n=201), 10 alleles for D8S1179 (n=198), 13 alleles for D18S51 (n=197) and 11 alleles for D19S253 (n=201). No deviation from Hardy-Weinberg equilibrium was found. Complete and relative uniformity in Caucasoid populations has been observed for D18S51 and D8S1179 respectively. Pronounced differences were found between different ethnic groups for both systems. Catalonia and Portugal do not differ for D3S1358 locus. Multiplex PCR amplifications of three loci (D3S1358, D18S51 and D19S253) without overlapping fragment size ranges could be interesting for monochrome automated laser fluorescence devices.