Color difference thresholds in dentistry.

PURPOSE: The aim of this prospective multicenter study was to determine 50:50% perceptibility threshold (PT) and 50:50% acceptability threshold (AT) of dental ceramic under simulated clinical settings. MATERIALS AND METHODS: The spectral radiance of 63 monochromatic ceramic specimens was determined using a non-contact spectroradiometer. A total of 60 specimen pairs, divided into 3 sets of 20 specimen pairs (medium to light shades, medium to dark shades, and dark shades), were selected for psychophysical experiment. The coordinating center and seven research sites obtained the Institutional Review Board (IRB) approvals prior the beginning of the experiment. Each research site had 25 observers, divided into five groups of five observers: dentists-D, dental students-S, dental auxiliaries-A, dental technicians-T, and lay persons-L. There were 35 observers per group (five observers per group at each site x7 sites), for a total of 175 observers. Visual color comparisons were performed using a viewing booth. Takagi-Sugeno-Kang (TSK) fuzzy approximation was used for fitting the data points. The 50:50% PT and 50:50% AT were determined in CIELAB and CIEDE2000. The t-test was used to evaluate the statistical significance in thresholds differences. RESULTS: The CIELAB 50:50% PT was DeltaEab = 1.2, whereas 50:50% AT was DeltaEab = 2.7. Corresponding CIEDE2000 (DeltaE00 ) values were 0.8 and 1.8, respectively. 50:50% PT by the observer group revealed differences among groups D, A, T, and L as compared with 50:50% PT for all observers. The 50:50% AT for all observers was statistically different than 50:50% AT in groups T and L. CONCLUSION: A 50:50% perceptibility and ATs were significantly different. The same is true for differences between two color difference formulas DeltaE00 /DeltaEab . Observer groups and sites showed high level of statistical difference in all thresholds. CLINICAL SIGNIFICANCE: Visual color difference thresholds can serve as a quality control tool to guide the selection of esthetic dental materials, evaluate clinical performance, and interpret visual and instrumental findings in clinical dentistry, dental research, and subsequent standardization. The importance of quality control in dentistry is reinforced by increased esthetic demands of patients and dental professionals

Reliability and Versatility of Reverse Sural Island Neurofasciocutaneous Leg Flaps

BACKGROUND Distally based sural neurofasciocutaneous (NFC) flaps are a commonly used method for foot and ankle reconstruction given that they are much simpler and, at the same time, still efficient alternative to perforator flaps and free style free flaps. OBJECTIVE This study aims to evaluate the reliability and versatility of reverse sural island NFC flaps as a powerful and efficient method that can be used for repair of lower leg skin defects. This method does not require microsurgical facilities or extensive training. METHODOLOGY Patients with soft tissue defects of the distal third of the leg and ankle region received reverse sural island NFC flaps. Inclusion criteria included an absence of damage to the sural neurovascular axis or communicating perforators, absence of peripheral vascular disease, and the presence of soft tissue defects deep enough to expose tendon or bone. Patients were assessed for flap (defect) size, pedicle length and location of defects, postoperative flap survival rates, and complications. Donor sites were closed directly or skin grafted. RESULTS Of 24 consecutive patient (20 male; 4 female), all flaps except 1 (4.16%), survived, although partial necrosis was observed in 2 patients (8.33%). The overall major complication rate was 12.50%. Epidermolysis was noted in 1 patient (4.16%). Three cases of transient venous congestion resolved without additional complications. The overall minor complication rate was 16.66%. Minimal complications were associated with healing of donor sites. CONCLUSIONS Reverse sural island NFC flaps provide adequate and aesthetically very acceptable coverage of soft tissue defects of the distal lower leg and proximal foot with no functional impairment

Influence of surface roughness on the color of dental-resin composites*

This study deals with the influence of surface roughness on the color of resin composites. Ten resin composites (microfilled, hybrid, and microhybrid) were each polished with 500-grit, 1 200-grit, 2 000-grit, and 4 000-grit SiC papers. The roughness parameter (R a) was measured using a Plμ confocal microscope, and field-emission scanning electron microscope (Fe-SEM) images were used to investigate filler morphology. Color was measured using a spectroradiometer and a D65 standard illuminant (geometry diffuse/0° specular component excluded (SCE) mode). Surface roughness decreased with grit number and was not influenced by filler size or size distribution. A significant influence of R a on lightness (L *) was found. Lightness increased with decreases in roughness, except for specimens that underwent polishing procedure 4 (PP4; 500-grit, 1 200-grit, 2 000-grit, and 4 000-grit SiC papers consecutively). Generally, it was found that surface roughness influenced the color of resin composites. The composites that underwent PP1 (500-grit SiC paper) exhibited significant differences in chroma (C *), hue (h°), and lightness (L *) compared to composites that underwent PP3 (500-grit, 1 200-grit, and 2 000-grit SiC papers consecutively) and PP4. Color difference (∆E*) between the polishing procedures was within acceptability thresholds in dentistry