Impact of rubber dam thickness on image quality parameters in photostimulable phosphor plates

The aim of this study is to investigate the effects of different rubber dam thicknesses on image quality in 2 exposure protocols.

For the study, 3 rubber dam thicknesses were used: thin (0.14 mm), medium (0.18 mm), and heavy (0.22 mm). To mimic clinical conditions, a rubber dam was used in 2 layers. Exposure was performed using 2 different protocols: Protocol 1: 0.080 s exposure time, 65 kV, 7 mA, and Protocol 2: 0.160 s exposure time, 65 kV, 7 mA. For each thickness and protocol, 47 measurements were taken (n = 47). Radiographic images were exported in TIFF and analysed using ImageJ software. The region of interest (ROI) was determined, and signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), Michelson, and Weber contrast values were obtained. One-way ANOVA, post hoc Tukey, and intra-class correlation were used for statistical analysis.

No statistical difference was detected for Protocol 1 between rubber dam thicknesses in SNR, CNR, Michelson, and Weber contrasts (P > .05). For protocol 2 (longer exposure time), heavy and medium thickness had lower SNR and CNR values than the thin one (P < .05). Michelson and Weber contrasts were statistically changed in different thicknesses of rubber dam (P < .05). ICC values were good and excellent.

The thick rubber dam reduced SNR and CNR values; likewise, Michelson and Weber contrasts were changed, which pointed a reduced image quality and negatively affected object visibility. Short exposure times are recommended to maintain image quality in clinical situations requiring the use of a thick rubber dam.