الفهرس 
HAIR BIOLOGYOnly 14 pages are availabe for public view
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Abstract
Nowadays, patients frequently present to dermatologists with hair problems some of which are medical while others are strictly cosmetic in nature. Because of that the dermatologist should be able to give patients sound advice on cosmetics that are safe and effective, and should be knowledgeable to advise them on what cosmetics they can use.
Cosmetics that are of common use are shampoos, conditioners, hair colourants, hair waving and straightening, hair styling aids, hair sunscreens and hair restoration methods.
Shampoos attempt to remove sebum, sweat components, environmental dirt, and desquamated stratum corneum from each individual hair shaft by employing detergents.
Shampoos are formulated as dry powder shampoos, liquid dry shampoos, clear liquid shampoos, lotion shampoos, shampoo pastes, aerosol shampoos, or oil shampoos.
Commercially, a number of different types of shampoos are available, Basic shampoos are used for either normal, dry, oily, or chemically treated hair. Other shampoos used are baby shampoos, conditioning shampoos, and medicated shampoos.
The action of a conditioner must be to soften, smooth, and restore the protective sheath i.e. to flatten or tighten cuticle scale and fill in the gaps, and provide resilience and bounce. In addition, conditioners should allow excellent ease of combing or brushing for wet and dry hair and should add luster to the hair.
Conditioning agents fall into four categories regarding their composition. Cationic detergents, film forming and Protein based conditioners beside the traditional oily materials.
Keratin is the most recent innovation in hair conditioning that protect hair from damage associated with chemical treatment such as perming and relaxation and help restore the mechanical strength of damaged fibers and decrease fading coloured hair.
One of the earliest known method for curling hair was used by the ancient Egyptians, who used mud and water to roll their hair and then sat in the sun until it dried. Later on, heat permanent waving method was invented in 1906.
In contrast to heat waving, cold waving requires no externally applied heat source to achieve the desired results, but relies instead on chemical reactions.
Hair straightening is a method devoted to the care of excessively curly hair. It started as hot combing process but nowadays chemical straightening are more widely used.
Hair colouring is not a modern cosmetic technique. It is well known that Egyptian women used kohl, a naturally occurring lead sulphide, to give a black colour to the hair, eye-brows, and eye lashes, besides henna which was also used for obtaining auburn tints.
There are basically four types of hair colourings: Bleaches, synthetic organic, vegetables and metallic dyes.
Bleaching can be used to remove both natural and artificial pigments. Bleaching is extremely damaging to the hair shaft.
Synthetic organic dyes contain the temporary hair colourants that is removed by a single shampooing, semi permanent hair colourants that will last through no more than 10 shampoos and permanent hair colourants which is the most popular form and also the most damaging to the hair shaft.
Vegetable dyes also called natural dyes, the most famous is Henna. Its dyeing properties is due to the presence of 2 hydro 1,4-naphthaquinone or lawsone.
Metallic dyes or gradual hair colourants that gradually darken the hair with continued daily application. The hair gradually changes from gray to a yellow brown to a black colour over a period of 2 to 3 weeks. These dyes leave the hair stiff, brittle and dull.
All hair styling aids have the same goal of maintaining the hair in a groomed position. Styling aids also provide conditioning, shine, body, and increased manageability. There are three categories of modern styling products: setting lotions and sprays, gels, and mousses.
In addition, hair styling can be achieved by using thermal styling equipments and devices e.g. electric curling irons or using non thermal styling devices like brushes and non electric rollers.
It has been found that sunlight does produce undesirable changes in hair quality. Dryness, reduced strength, rough surface texture, loss of colour and luster, stiffness and brittleness have been reported.
In general, it has been demonstrated the superiority of benzophenones in protecting both hair colour and structure as hair sunscreens.
Mesotherapy, a technique involving injections of medications directly into the skin was proven to improve cases of Alopecia when injecting substances such as minoxidil.
Hair addition is a technique performed to add length, volume, to create styles, and to replace hair that is missing.
Hair transplantation has significantly improved its cosmetic and therapeutic benefits for both male and female patients. On the other hand, artificial hair or wigs are used cosmetically for those patients who have temporary or permanent hair loss and can not undergo surgical procedures for hair restoration.