Color difference threshold determination for acrylic denture base resins

Abstract

Abstract. This study aimed to set evaluation indicators, i.e., perceptibility and acceptability color difference thresholds, of color stability for acrylic denture base resins for a spectrophotometric assessing method, which offered an alternative to the visual method described in ISO 20795-1:2013. A total of 291 disk specimens 50±1 mm in diameter and 0.5±0.1 mm thick were prepared (ISO 20795-1:2013) and processed through radiation tests in an accelerated aging chamber (ISO 7491:2000) for increasing times of 0 to 42 hours. Color alterations were measured with a spectrophotometer and evaluated using the CIE L*a*b* colorimetric system. Color differences were calculated through the CIEDE2000 color difference formula. Thirty-two dental professionals without color vision deficiencies completed perceptibility and acceptability assessments under controlled conditions in vitro. An S-curve fitting procedure was used to analyze the 50:50% perceptibility and acceptability thresholds. Furthermore, perceptibility and acceptability against the differences of the three color attributes, lightness, chroma, and hue, were also investigated. According to the S-curve fitting procedure, the 50:50% SHUFHSWLELOLW\ WKUHVKROG ZDV ¨(00 (r 2 =0.88) and the 50:50% DFFHSWDELOLW\ WKUHVKROG ZDV ¨(00 (r 2 =0.89). Within the limitations of this study, 1.71/4.00 ¨E00 could be used as perceptibility/acceptability thresholds for acrylic denture base resins.

Color stability of repairs on bis‐acryl resin submitted to thermal aging and immersion in beverages

“…In the present study, resins (bis‐acryl and flowable resin) from the same manufacturer and from the same batch were selected. Although they are commercialized in the same color (A2), the results suggest a different colorimetric behavior among the materials, which may result in a clinical problem, because the differences found are higher than the acceptable thresholds described in the literature …”

“…Ren et al provided perceptibility threshold (PT)/acceptability threshold (AT) for acrylic resins (1.7/4.0 Δ E 00 ) using the CIEDE 2000 formula. If we compare the results found in the present study with those thresholds proposed, the color differences found between the groups (BCR‐BCR = 1.2, BCR‐FR = 5.6, and BCR‐AFR = 5.0 Δ E 00 ) were perceptible and acceptable only for the group repaired with the same bis‐acryl composite resin.…”

“…Although they are commercialized in the same color (A2), the results suggest a different colorimetric behavior among the materials, which may result in a clinical problem, because the differences found are higher than the acceptable thresholds described in the literature. 27,28 The recommendation of the use of flowable resin by the manufacturer is based on the ease and speed of the repair procedure, because a small amount of resin can be placed directly on the failure, saving material, and clinical time. 1 When the repair is done with the bis-acryl composite resin by the traditional self-mixing technique, a large amount of material is discarded inside the mixing tip, resulting in a higher consumption of material.…”

Effect of nanoscale particles incorporation on microhardness of polymers for oral prosthesis

“…[3] After baseline hardness measurement, discs were thermocycled in a thermocycling simulation machine (MSCT-3, Convel, Aracatuba, Sao Paulo, Brazil).…”

“…Several nanoscale pigments as dark carbon (C), zinc oxides (ZnO), titanium (Ti), and iron (Fe) have been incorporated into acrylic resins for improving the esthetic of the denture base. [23]…”