An In Vitro Evaluation of the Effect of Sealant Characteristics on Laser Fluorescence for Caries Detection

Resident’s Name: Anna Haritos Date: March 13, 2009
Author(s): Gostanian, Harout V et al.
Journal: Pediatric Dentistry
Volume (number): 28:5
Month, Year: 2006, 445-450
Major topic: laser fluorescence use for caries detection under sealants
Minor topic(s): use of opacifying agent in sealant to attenuate laser fluorescence
Type of Article: research article
Main Purpose(s): 1)evaluate the ability of a laser fluorescence (LF) unit to detect simulated caries under pit and fissure sealants; 2) determine the effect of an opacifying agent in sealants on LF values; & 3) determine interexaminer reproducibility values of the unit in a highly controlled laboratory setting
Overview of method of research: three sealant types were used, 1 filled and 2 unfilled. Titanium dioxide powder was added in varying amounts to all three sealant types to create opacity; the amounts were by weight and were 10%, 1%, 0.5%, 0.25%, 0.1% and 0%. Sealant disks were created for each type of sealant of 0.5 mm thick. The LF was calibrated according to the manufacturer with a calibration disk. Wells were filled with 0.3 mg, 0.5 mg and 1.2 mg of protoporphyrin IX powder and read with the DIAGNOdent to achieve baseline readout values of 10, 20 and 60 respectively. The protoporphyrin has been shown to be the fluorescing chromophore naturally found in carious lesions, so was chosen to mimic caries in this study. Each disk type was placed on to a well, which was filled with varying amounts of protoporphyrin IX disodium salt, and Peak readings were recorded. Attenuation of the laser signal was determined by subtracting the fluorescence of the sealant-disc-covered protoporphyrin IX from the baseline value. Peak intrinsic fluorescence values were recorded for each sealant disc type off of the wells as well. The operator was blinded to the reading panel during the measurement to avoid bias. Data was analyzed by ANOVA; the value was P<.05
Findings: LF readings are reproducible. All three sealant types interfered with the LF signals, with filled sealants attenuating the LF reading significantly more so than did unfilled sealants. As percentage of titanium dioxide powder increased so did the intrinsic fluorescence of the sealant disks. Once the concentration of titanium dioxide reached 0.5%, the fluorescence signal was almost fully attenuated. With the clear sealant (unfilled) the amount of true signal transmission was 68%. When one increases the baseline protoporphyrin IX levels or increases the thickness the transmission is worsened.
Key points/Summary: This study looked at how the intrinsic fluorescence of a sealant affects LF readings; It showed that the fluorescence will be picked up in the reading as well as the caries, but that this can not be differentiated in the reading. DIAGNOdent is a low-power diode laser unit operates at 100 mW producing enery in the visible spectrum. The DIAGNOdent has been shown to have a high sensitivity for caries detection. Titanium dioxide is an opacifying agent often added to sealants to increase the white color
Assessment of article: Good article – makes one question the use of the DIAGNOdent.