Determining the perceptibility and acceptability threshold of the relative translucency parameter- A pilot study

This study aimed to determine the perceptibility and acceptability thresholds for the relative translucency parameter (RTP) of ceramic materials, using observer-based assessments under simulated clinical conditions. The null hypothesis was that no difference existed in RTP values for perceptibility and acceptability thresholds.

Specimens of lithium disilicate in five translucency levels were fabricated into discs and anterior crowns. RTP was calculated using the CIEDE2000 color difference formula with black and white backings. Digital photographs of paired crowns on typodont models were presented to 30 dental clinicians in a controlled visual environment using a randomized Qualtrics survey. Observers judged translucency differences (perceptibility) and clinical appropriateness (acceptability). A repeated-measures logistic regression model was used to analyze observer responses.

A significant relationship was found between Delta RTP (△RTP) and both perceptibility and acceptability judgments (p < 0.0001). Perceptibility thresholds were identified at -17.5, while acceptability thresholds were defined at 12.6. △RTP values exceeding 27 were consistently perceived as different, while values below 12 were often judged acceptable. The null hypothesis was rejected, confirming a statistical difference between perceptibility and acceptability judgments and their relationship to RTP.

Clinically relevant RTP thresholds for translucency perception and acceptability were established. These findings validate RTP as a meaningful and quantifiable tool for assessing esthetic differences in translucency among restorative materials. The results have implications for material selection and clinical decision-making in prosthodontics.