The Keratinization of Gingival Epithelium

Abstract

K ERATINIZATION is a process peculiar to squamous epithelium and its appendages and has been defined as "the transformation of living cells into horny material." 1 In spite of intensive research into the chemistry and cytology of keratinizing cells, however, the underlying process is still incompletely understood.It was thought at one time that keratinization was a result of cell degeneration and destruction. Evidence that the presence of connective tissue 2 and adequate nutrition 3 were necessary for the process showed that this belief was false and it is generally accepted today that keratinization is not a type of degeneration but is the final stage in a process of intrinsic differentiation. 1The epithelium of the palate and attached gingivae is normally keratinized 4,5 although attached gingival epithelium tends to be parakeratotic in patients who do not practice good oral hygiene. 6 There is some disagreement on whether or not the epithelium lining the gingival crevice is keratinized. Many have maintained that it is, 7-13 while others have held the contrary view. [14][15][16] The present study was planned with two objects in view. The first was to compare the type of keratinization seen in the gingivae with that found in skin, and the second was to study the distribution of keratinization in gingival epithelium.In addition to comparing the histological structure of these types of epithelium, three other features were studied. These were the distribution of sulphydryl groups, disulphide groups, and birefringence.Sulphur metabolism has been shown to be important in keratinization. It is believed that, in keratinizing epithelium, the cells gradually accumulate sulphydryl groups which are oxidized to disulphides where actual keratin formation is taking place. The disulphides then form crosslinkages between the polypeptide chains of the keratin.

Application of stereologic methods to stratified gingival epithelia*

“…The integument of the oral cavity, which is generally stratified squamous epithelium, varies mainly with regard to the presence and degree of lreratinization. Various oral epithelia have been studied by light and electron microscope in animals (Albright & Listgarten, 1962;Gibbins, 1962;McHugh, 1964;Stern, 1965;Gavin, 1968) and in man (Wentz et al, 1952;Dewar, 1955;Trott, 1957; Sognnaes & Albright, 1958;Weinmann & Meyer, 1959;Fasske & Themann, 1959;Zelickson & Hartmann, 1962;Kurahashi & Takuma, 1962;Listgarten, 1964Listgarten, , 1966Hashimoto et al, 1966;Schroeder & Theilade, 1966;Bulow, 1966;Thilander, 1968;Silverman, 1967). These studies were predominantly descriptive morphological investigations.…”