Stephen Westland

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INTRODUCTION There is evidence to suggest that Ledermix, placed as an intervisit root canal dressing, might improve periodontal healing after replantation of avulsed teeth. As a part of a multicenter randomized controlled trial, we aimed to compare the effect of 2 root canal medicaments, Ledermix and Ultracal XS, on the discoloration of replanted teeth. (More)
OBJECTIVES To review current knowledge on the definition of tooth whiteness and its application within dentistry, together with the measured range of tooth colours. METHODS 'Medline' and 'ISI Web of Sciences' databases were searched electronically with key words tooth, teeth, colour, colour, white and whiteness. CONCLUSIONS The application of colour(More)
Perceptual transparency was measured in two experiments by using simulations of illuminated surfaces presented on a CRT monitor. In a two-alternative forced-choice paradigm, observers viewed two simulated Mondrians in temporal sequence. In one sequence the Mondrian was simulated to be partially covered by a transparent filter; in the other sequence the(More)
We investigate methods for the recovery of reflectance spectra from the responses of trichromatic camera systems and the application of these methods to the problem of camera characterization. The recovery of reflectance from colorimetric data is an ill-posed problem, and a unique solution requires additional constraints. We introduce a novel method for(More)
UNLABELLED When we observe the light reflected from surfaces in a scene or look directly at light emitted by light sources, we experience the sensation of color. Color is just one attribute of a complex and not fully understood set of properties that define the appearance of our surroundings. To measure or specify the color of an object, we need to take(More)
This study concerns the roles of absolute and relative orientation in determining detectability of a line-element target in a background field of uniformly oriented line elements. Target detectability was determined as a function of background-field orientation, sampled at 5 deg intervals, for three levels of orientation contrast--the difference between(More)
OBJECTIVES To evaluate the in vitro blending effect (BE) of layered resin composites related to material, shade, and differences in color and translucency between compared materials. METHODS Specimens made of two composites (2CS, n=5) consisted of the outer composite with an outer diameter of 10mm, 4mm thick and an inner diameter of 4mm, 2mm thick for the(More)
This paper compares the performance of a number of linear methods for reflectance estimation from digital camera responses. Methods based upon smoothness maximisation, linear models of reflectance and least-squares fitting are compared using two simulated 6-channel camera systems. In our experiments, the smoothness methods were generally found to deliver(More)
This study investigated various uncertainties in colour matching, including matching stimulus and measuring instruments (such as random fluctuation, drift over time, spatial uniformity, temperature), calibration (photometric, wavelength and additivity) and observer (intraand inter agreements). From the research results, it was found that the observer error(More)