Pellicle, acquired, formation

Besides taking part in acquired pellicle formation on tooth (denture, implant) surfaces, MUC5B type mucins cover all oral surfaces with a 10-20- im thick layer. In addition, MUC5B type mucins form a hydrophilic viscoelastic gel (already in low concentration) that causes a high viscosity matrix of saliva. 

The calculus reviews cited earlier [1, 16, 30, 31] discuss the role of saliva and its constituents in the context of mineral formation and dissolution in plaque. Other authors have reviewed saliva with respect primarily to dental caries [e.g. 54, 55], caries models [56, 57] and the acquired pellicle [58]. 

The most important components are probably the proteins, and the possible roles of these molecules in caries, in particular, have been studied extensively. An obvious inhibitory function of the salivary proteins is the formation of an adsorbed layer on the teeth, the acquired pellicle. For more details on the composition and function of pellicle the reader is referred to chapter 2 and ref. 58. 

Formation of the acquired salivary pellicle is the result of biopolymer adsorption at the tooth-saliva interface. The term acquired pellicle was first suggested in a review of the nomenclature of the enamel surface integuments by Dawes et al. [1], to describe the cuticular material formed on the enamel surface after eruption. The pellicle consists of adsorbed proteins and other macromolecules from the oral environment (saliva, crevicular fluids) and is clearly distinguished from the microbial biofilm (plaque) (fig. 1). 

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 formation is determined by adsorption of components from saliva, crevicular fluid and bacteria onto the enamel surface [2-13], Formation of the acquired pellicle is a highly selective process, since only a fraction of the proteins available in saliva is found in the pellicle [14,15],... 

Sonju T, Rolla G Chemical analysis of the acquired pellicle formed in two hours on cleaned human teeth in vivo. Rate of formation and amino acid analysis. Caries Res 1973 7 30-38. 

In Chapter 2 the structure and function of the acquired enamel pellicle are discussed. Recent work, aided by advances in analytical methodologies, has increased our understanding of pellicle formation and maturation, and how pellicle composition relates to saliva. The authors emphasize the important role played by pellicle in plaque attachment, tooth protection and stain formation. The authors also describe research on the potential effects that dentifrices can have on pellicle. 

The idea of a hydrophobic film covering the exposed enamel is attractive. In theory a charged head group would bind to the apatite and a hydrophobic tail , such as the hydrocarbon chains found in fatty acids and in phospholipids, would be presented to the saliva. In this way bacterial adhesion and plaque formation could be reduced. The precipitation of specific salivary proteins to produce the acquired pellicle has much the same effect and it is interesting to note that treatment of an apatite surface with hydrophobic salivas reduced the attachment of 5. mutans and other hydrophilic streptococci. 

First, bacterial adhesion (usually gram-positive cocci and filamentous bacteria) occurs primarily through a Ca + complex formation between carboxyl (COO ) and phosphate (HPOs ) groups of bacterial surface and acquired pelhcle, although van der Waals forces and repulsive electrostatic forces are also present. Some specific bacterial surface proteins also serve as adhesins for specific receptors on acquired peUicle. Pellicle-integrated immunoglobulins also bind bacteria specifically. 

Bennick A, Chau G, Goodlin R, Abrams S, Tustian D, Madapallimattam G The role of human salivary acidic proline-rich proteins in the formation of acquired dental pellicle in vivo and their fate after adsorption to the human enamel surface. Arch Oral Biol 1983 28 19-27. 

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