Teeth pellicle

Abrasive. Dentifrices have the unique ability to remove extrinsic tooth stains, which are caused by agents such as berries, tea, smoking, antibiotics, and certain bacteria as they attach to the dental pellicle. These stains can be removed only by abrasive cleaning a toothbmsh alone is not adequately effective. It has been shown that only 4% of a test population were able to maintain thein teeth in an acceptably stain-free state without an abrasive and that 18% of the population were "heavy" stainers (2). However, colored materials found in dental plaque are removable without abrasives. 

It is now known that teeth undergo a continuous process of demineralisation and remineralisation (see Table 2), which is driven by changes in the plaque composition [29]. In the presence of fermentable carbohydrates plaque microorganisms generate characteristic organic acids, that is, lactic and acetic [17], and these diffuse through the pellicle to the tooth surface and cause demineralisation [30]. Ions are then liberated from the mineral phase into this low pH liquid [31], and they diffuse outwards and re-precipitate at the surface layer of the demineralised lesion [32,33]. If this process is sufficiently rapid, there is a net loss of tooth mineral and irreversible cavity formation. 

C.W. Mayhall, Concerning the composition and source of the acquired enamel pellicle of human teeth, Arch. Oral Biol. 15 (1970) 1327-1341,... 

The amino acid composition of the protein portion of a 2-hour pellicle acquired in vivo on human teeth was the subject of a communication by Sonju and Rolla (13). Their data (Table I) are significant because, unlike previous studies in which pellicle films were obtained by acid demineralization of tooth enamel, their pellicle preparation was removed by careful scaling only. No significant differences were observed in findings for various teeth, an observation that supports selective adsorption... 

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. 

A possible source of some of the variation in the above studies may well be degradation of salivary proteins by proteolytic enzymes in the mouth. Bennick et al. [98] found that pellicles formed in situ on pieces of enamel and more than 24 h old showed degradation of adsorbed proline-rich proteins, and that old pellicle from extracted teeth contained very little of these proteins. A more recent report from the same laboratory [99] described large numbers of small phosphoproteins in samples of whole saliva, which were mostly fragments of acidic proline-rich proteins and indicated rapid degradation. In apparent contrast, Lamkin et al. [100] found that the magnitude of proteolysis of whole saliva samples was much smaller than they had expected, albeit by an ex vivo adsorption technique. 

Studies on pellicle composition are hampered by the fact that only limited amounts (minute quantities) of pellicle material can be collected and recovered from human teeth in vivo for analytical investigations. It has been calculated that the pellicle layer formed per labial surface of a tooth over 2 h in vivo only contains approximately 1 xg of protein [39], Therefore, much work has been performed using in vitro models to mimic the formation of the salivary pellicle. Glandular salivary secretions or whole saliva supernatants are used to form a pellicle-like protein layer adsorbed on hydroxyapatite or tooth enamel. Although considerable insight into the selectivity and affinity characteristics of salivary proteins during adsorption onto these surfaces has been obtained from... 

In the 1970s, it was demonstrated that there were no systematic differences in the principal composition of the pellicle layer formed in different areas of the oral cavity [5], Amino acid compositions of pellicles collected from the buccal sites of the upper molars, upper incisors and lower anterior teeth were found to be virtually identical [5], In addition, amino acid analyses also indicate that the composition of the pellicle is consistent not only within, but also between individuals [12, 44], A considerable intersubject consistency has been described concerning the composition of the in vivo-formed salivary pellicle layer [12, 39, 40, 45],... 

From early TEM studies, matured in vivo-formed pellicle has been described as a homogeneous and amorphous, bacteria-ffee surface coating of varying thickness [62-64, 67] (table 2). Less pronounced pellicle formation has been reported on lingual and labial sites of the teeth, as compared to the proximal areas [62, 63, 67], In self-cleansing sites of the teeth, the pellicle thickness ranges between 30 nm and 80nm [63], whereas in proximal areas the pellicle can be up to 2-pm thick [63],... 

Most of these ultrastructural investigations were performed on enamel slabs carried in the buccal sulcus or mounted on the buccal sites of the teeth. However, within the oral cavity, saliva provides a series of distinctly different fluid environments [74], and secretions from different salivary glands vary considerably and have a specific protein composition [75], Consequently, more recently published electron microscopic and CLSM studies have focussed on site-dependent differences in the formation (morphogenesis) of the in vivo pellicle [17,28]. 

Fig. 5. TEM images of the 2-hour pellicle layer formed in situ on the surface (left) or within slots (right) of enamel specimens exposed to the oral environment on the buccal (top) or palatal site (bottom) of the upper first molar teeth. Comparison of the pellicle layers formed on the surface or within slots (i.e. shielded from shearing forces) does not reveal differences in thickness and ultrastructure of the adsorbed protein coatings. However, clear differences are evident between the pellicles formed within 2 h on buccally and palatally exposed enamel slabs. On the palatally carried enamel specimens - even within the slots - an outer globular pellicle layer cannot be detected. Bar = 200 nm. 

Only limited information is available from the literature concerning the behaviour of the pellicle during daily brushing of the teeth with a dentifrice. It has been reported from in vitro and in vivo studies that brushing with commercially available dentifrices significantly reduces the pellicle film quantity and its thickness [170-174], Conversely, brushing with a nonabrasive dentifrice leads to a thick and often-stained pellicle [139, 175],... 

After brushing, the pellicle rapidly reforms and provides protection to the enamel surface against acid attack even after a formation time of only 3 min [99]. Thus, loss of any of the pellicle during daily brushing of the teeth does not seem to have a major impact, and does not have any clinical relevance concerning pellicle-related protection of these enamel surfaces. 

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. 

Sonju Clasen AB, Hannig M, Skjarland K, Sonju T Analytical and ultrastructural studies of pellicle on primary teeth. Acta Odontol Scand 1997 55 339-343. 

Carlen A, Rudiger SG, Loggner I, Olsson J Bacteria-binding plasma proteins in pellicles formed on hydroxyapatite in vitro and on teeth in vivo. Oral Microbiol Immunol 2003 18 203-207. Rudiger SG, Carlen A, Meurman JH, Kari K, Olsson J Dental biofilms at healthy and inflamed gingival margins. J Clin Periodont 2002 29 524-529. 

Saliva is the body s natural protective mechanism against decay. It contains salivary proteins which adsorb strongly onto the teeth to form a layer which is referred to as the salivary pellicle. 

The chemical composition of old pellicle samples has been reported to be 46% amino acids, 2.7% hexosamines and 14% total carbohydrate [40]. Amino acid compositions of pellicle collected from different teeth are virtually identical [41] and compositions of 2-hour acquired enamel pellicle have been found to be consistent over a period of 24 months [42], In contrast, 24-hour pellicles exhibit significant variability when subjects have consumed a normal diet. An amino acid composition similar to that of enamel pellicle has been found for the film on the sides of maxillary dentures [43], These results suggest that most oral surfaces bathed with saliva acquire a protein coating with a composition similar to that of enamel pellicle [44],... 

Finally, the ameloblasts secrete an unusual basal lamina, which partially mineralizes into the surface enamel crystals, the enamel cuticle. By this time, the enamel organ has shrunk so that its outer layers have merged with the ameloblast layer at the completed enamel surface postmaturation stage). This reduced enamel epithelium is rubbed off as the teeth erupt, but the enamel cuticle is abraded more slowly and gradually replaced by proteins from saliva, the acquired pellicle (Sect. 12.1.3). 

Salivary a-amylase is a protein that contributes to the enamel pellicle (Sect. 12.1.3). More importantly, it attaches bacteria, especially streptococci, to teeth surfaces. Thus, following a meal rich in carbohydrates, amylopectin, amylase, and glycogen are digested to maltose at the surface of many oral bacteria. The maltose is taken into the cytosol by a phosphoenolpyruvate transporter homologous to the fructose transporter of S. mutans. Within these bacteria, the maltose is digested to two molecules of glucose 6-phosphate and metabolized to lactic acid. Thus, twice as much acid is produced per mole maltose than per mole sucrose and it contributes to tooth demineralization even if less sucrose is consumed. 

The test plates can be made in almost any shape and size, and placed in special intraoral holders worn in mouths of human volunteers. Such holders provide means to analyze the "skin" on one s teeth, the pellicle acquired by specific adsorption of salivary components before any successful colonization by microbial flora is noted (12). 

A In situ measurements from 76 test subjects 29 female and 47 male. Measurements made on teeth with intact pellicle (i.e., biofilm). 7/ only calculated from glycerol and thiodiglycol. t Average of 4 teeth from 2 subjects, calculated from non-polar liquids. 

The mechanism of pellicle formation is far firom clear but there is no doubt that it forms rapidly on all enamel surfaces. Although there is justification for regarding it to be normal for a tooth to be covered with pellicle, there is considerable controversy as to whether this integument has any function. It may protect the teeth against add attack, and abraded areas of enamel are undoubtedly more susceptible to decaldfication, but it has not been proved whether this is due to removal of the pellicle or of some other components of the enamel siurface. The presence of... 

Plaques—Plaques vary in thickness, and are composed of about 70% bacteria, with the remaining 30% being polysaccharides, enzymes, and acids. Unless a tooth has been thoroughly cleaned, the bacteria colonies in plaques continue to grow, particularly near the gum line (gingival sulcus). A thin organic layer, the pellicle, between the tooth enamel and the plaque is formed when proteins in the saliva are adsorbed on the enamel. It seems that the pellicle promotes the attachment of bacteria to the teeth and influences the transport of acids into the enamel and diffusion of calcium and phosphate out of the enamel. Accumulations of plaques are implicated in caries and periodontal disease. 

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