Male versus female skin: What dermatologists and cosmeticians should know.

INTRODUCTION: The skin is important for the perception of health and beauty. Knowledge of the physiological, chemical, and biophysical differences between the skin of male and female patients helps dermatologists develop a proper approach not only for the management of skin diseases but also to properly take care of cosmetic issues. The influence of genetic and environmental factors on skin characteristics is also critical to consider. METHODS: A literature search of PubMed and Google was conducted to compare the biophysical and biomechanical properties of the skin of male and female patients using the keywords "skin", "hydration", "water loss", "sebum", "circulation", "color", "thickness", "elasticity", "pH", "friction", "wrinkle", "sex", "male", and "female". RESULTS: A total of 1070 titles were found. After removing duplications and non-English papers, the number was reduced to 632. Of the 632 titles, 57 were deemed suitable for inclusion in this review. The studies show that the skin parameters of hydration, transepidermal water loss, sebum, microcirculation, pigmentation, and thickness are generally higher in men but skin pH is higher in women. CONCLUSIONS: These parameters can be considered as age markers in some cases and are susceptible to change according to environment and life style. Biometrological studies of the skin provide useful information in the selection of active principles and other ingredients of formulations to develop a specific approach for cosmetic treatments.

Bateman purpura (dermatoporosis): a localized scurvy treated by topical vitamin C - double-blind randomized placebo-controlled clinical trial.

BACKGROUND: Bateman purpura is characterized by diffuse senile skin atrophy, senile purpura and spontaneous stellar pseudocicatrices. Cutaneous changes in the course of ageing have been related to lower levels of ascorbic acid into the dermis of elderly people. OBJECTIVE: In this study, we postulate that senile purpura could be linked to dermal vitamin C deficiency and could be corrected by topical administration of this vitamin. METHODS: A 12-weeks, hemi-member (forearm or leg), randomized double-blind comparative study was conducted in 18 patients with Bateman purpura aged over than 60 years. At each visit, clinical assessment and biometrological measurements were performed. Clinical examination and scoring by experts showed a significant improvement on the vitamin C-treated side compared with the control, with reduction of haemorrhage areas, increase of dermal thickness. RESULTS: Twice-daily application of 5% topical vitamin C led to a clinically apparent improvement of the skin symptoms and allows beneficial effects on skin elasticity and thickness. Bateman purpura, a classical sign of photoaging whose origin has not clearly been recognized could be improved by vitamin C applied on to the skin. CONCLUSION: These results confirm the hypothesis of the underlying role of vitamin C deficiency in the determinism of Bateman purpura.

The influence of gender and age on the thickness and echo-density of skin.

BACKGROUND: The more recent use of ultrasound scanning allows a direct measurement on unmodified skin, and is considered to be a reliable method for in vivo measurement of epidermal and dermal thickness. The objective of this study was to assess the influence of gender and age on the thickness and echo-density of skin measured by high frequency ultrasonography (HFUS). MATERIALS AND METHODS: This study was carried out on 30 healthy volunteers (17 female, 13 male) with age range of 24-61 years old. The thickness and echo-density of dermis as well as epidermal entrance echo thickness in five anatomic sites (cheek, neck, palm, dorsal foot, and sole) were measured using two different types of B mode HFUS, 22 and 50 MHz frequencies. RESULTS: The epidermal entrance echo thickness and thickness of dermis in males were higher than females, which was statistically significant on neck and dorsum of foot. The echo-density of dermis was higher in females on all sites, but was only statistically significant on neck. The epidermal entrance echo thickness and thickness of dermis in young age group was statistically higher than old group on sole and dorsal of the foot respectively. Overall, the skin thickness decreased with age. CONCLUSION: High frequency ultrasonography method provides a simple non-invasive method for evaluating the skin thickness and echo-density. Gender and age have significant effect on these parameters. Differences in study method, population, and body site likely account for different results previously reported.

Double-layer color effects in porcelain systems.

The color of an unshaded body porcelain was determined at three thicknesses on white, gray, and three chromatic backings. Spectral absorption and scattering coefficients of the porcelain were determined from the diffuse reflectance at one thickness on the white and gray backings. These optical coefficients, when utilized with the Kubelka-Munk reflectance theory, accurately predicted the color of the other sample configurations studied. The scattering of the body porcelain was found to decrease with increasing wavelength within the visible spectrum, in accordance with scattering theory for particles not substantially less than the wavelength of the scattered light. For the filtering effects of a translucent material in optical contact with a backing, the Kubelka-Munk reflectance theory described the interaction between the optical absorption and scattering within the translucent material and the reflectance of the backing.

The surface roughness and gloss of composites.

The contrast gloss and the average roughness were measured for four commercial composite filling materials. Using a factorial design, each material was subjected to four available finishing methods. A significant difference was found in the contrast gloss among finishing methods, and a significant linear regression is given which relates the inverse of the contrast gloss to the average roughness. Surface gloss is proposed as playing a major role in the esthetic appearance of composite restorations.