Chlorhexidine, pellicle staining

This review covers the formation, composition, structure, function and properties of the acquired pellicle. Specifically, the formation of pellicle is considered in terms of thermodynamic and kinetic aspects. The composition of the pellicle is reviewed in terms of the proteins, carbohydrates and lipids that have been identified using a range of analytical techniques. The ultrastructure of the pellicle is described in some detail from studies involving enamel slabs carried in the mouth, in which the subsequent pellicle was analysed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and confocal laser scanning microscopy (CLSM). The function of the pellicle is outlined in terms of its lubrication properties, its ability to act as a semi-permeable membrane and its overall protection of the underlying enamel surfaces. Since pellicle is formed at the interface between the enamel surface and the oral environment, the important process of bacterial attachment to the pellicle surface is described and the specific bacterial binding sites found in the pellicle are summarised. The influence of diet and nutrition on the pellicle layer is considered. The formation of extrinsic stain is discussed in particular, the role that chlorhexidine... 

Pellicle has a tendency to develop stain, termed extrinsic stain, particularly in those areas of the dentition which are inaccessible to toothbrushing and the abrasive action of a dentifrice [137-139], Extrinsic staining has been reported to be promoted by smoking, dietary intake of tannin-rich foods (e.g. tea, red wine) and the use of certain cationic agents such as chlorhexidine, tin and iron [140-144], Proposed mechanisms of extrinsic stain formation have been reviewed over the years by a number of authors [140,145-148] and the focus of recent attention has been the staining associated with chlorhexidine. 

Nordbo H, Eriksen HM, Rolla G, Attramadal A, Solheim H Iron staining of the acquired pellicle after exposure to tannic acid or chlorhexidine preliminary report. Scand J Dent Res 1982 90 117-123. 

At present chlorhexidine is the agent of choice in the short-term control of supragingival plaque although it is not without its disadvantages. It adsorbs to a pellicle-covered enamel and to the surface of calculus and subsequently reacts with dietary components to produce a persistent brown stain. In addition, some patients report a burning sensation and loss of taste after prolonged use. 

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