Journal - European journal of oral sciences (Denmark )

Journal - Journal of the American Dental Association (1939) (United States )

Abstract :

BACKGROUND: This nonsystematic review summarizes the effects of saliva on some of the diseases affecting the hard and soft oral tissues. RESULTS: Saliva enters the mouth at several locations, and the different secretions are not well-mixed. Saliva in the mouth forms a thin film, the velocity of which varies greatly at different sites. This variation appears to account for the site specificity of smooth-surface caries and supragingival calculus deposition. Saliva protects against dental caries, erosion, attrition, abrasion, candidiasis and the abrasive mucosal lesions seen commonly in patients with hyposalivation. These effects are the result of saliva's being a source of the acquired enamel pellicle; promoting the clearance of sugar and acid from the mouth; being supersaturated with respect to tooth mineral; containing buffers, urea for plaque base formation, and antibacterial and antifungal factors; and lubricating the oral mucosa, making it less susceptible to abrasive lesions. CLINICAL IMPLICATIONS: For optimal oral health, people should keep food and liquids in the mouth as briefly as possible. The most important time for toothbrushing is just before bedtime, because salivary flow is negligible during sleep and the protective effects of saliva are lost. Chewing sugar-free gum or sucking on sugar-free candies stimulates salivary flow, which benefits hard and soft oral tissues in many ways.

Journal - Journal (Canadian Dental Association) (Canada )

Abstract :

This case report describes the almost complete loss of enamel by acid erosion, particularly from the anterior teeth, in a woman who swam daily for 2 weeks in an improperly chlorinated swimming pool in Cuba. It emphasizes the need for both swimmers and swimming pool staff to ensure that the water has been properly chlorinated and that the pH has been adjusted to 7.5.

Journal - Journal (Canadian Dental Association) (Canada )

Abstract :

Many authors have assumed that the reason supragingival calculus tends to form preferentially on the lingual surface of the 6 lower anterior teeth is because saliva from the adjacent submandibular ducts is a source of calcium and phosphate ions and because loss of CO2 as the saliva enters the mouth increases the local pH. However, the fluid phase of plaque in all locations is supersaturated with respect to the calcium phosphates in calculus and there is always a tendency for calculus to deposit, except after sugar consumption, when plaque pH may fall below the critical level and the plaque fluid becomes unsaturated. pH is least likely to fall below the critical level in plaque lingual to the lower anterior teeth, as this plaque is very thin, sugar concentration after sugar intake is lowest in that area and its clearance rate is fastest, and the high salivary film velocity there promotes loss of any acid formed in plaque. A high salivary film velocity also brings more salivary urea to the site, which facilitates plaque alkalinization. These factors all contribute to the development of shallow Stephan curves of short duration and together provide a more reasonable explanation for the fact that supragingival calculus deposition progresses most easily on the lingual surface of the lower anterior teeth.

Journal - Journal (Canadian Dental Association) (Canada )

Abstract :

The objective of this study was to compare unstimulated salivary flow rate and residual salivary volume (the volume of saliva retained in the mouth after swallowing) in a group of 23 control subjects and a group of 25 patients who had received radiation treatment or had undergone removal of the salivary glands (or both) for head and neck cancer. As expected, the mean flow rate (+/- 0 standard deviation) in the patient group was significantly less than that in the control group (0.07 +/- 0.11 and 0.45 +/- 0 0.27 mL/min, respectively). However, the mean residual volumes were not significantly different between the 2 groups (0.70 +/- 0 0.28 and 0.82 +/- 0 0.26 mL, respectively). The 25 patients were subdivided according to their self-reported assessment of the mouth as being not dry (3), somewhat dry (12) or very dry (10); mean residual volume of saliva was significantly lower, at 71% the level in control subjects, for the group with very dry mouth (p < 0.02). These results suggest that people who report that the mouth is dry may not have a complete lack of fluid in the mouth; rather, there may be localized areas of dryness, notably on the hard palate, where the salivary film is particularly thin and subject to fluid absorption or evaporation because of mouth breathing.

Journal - Journal (Canadian Dental Association) (Canada )

Abstract :

This paper discusses the concept of critical pH for dissolution of enamel in oral fluids. The critical pH does not have a fixed value but rather is inversely proportional to the calcium and phosphate concentrations in the solution. The paper also discusses why teeth dissolve in acid, why remineralization of white-spot caries lesions is possible and why remineralization of teeth eroded by acid is not possible.

Journal - Compendium of continuing education in dentistry. (Jamesburg, N.J. : 1995). Supplement (United States )

Abstract :

Because many factors influence the acid-forming ability of dental plaque in the mouth, a model system was used in which reproducible Stephan curves could be generated after exposure of a gel-stabilized plaque to sucrose. Simulation of the use of a high-bicarbonate dentifrice at a time when plaque pH had fallen to about 4.5 caused a rapid return of the pH toward neutrality, whereas simulation of the use of a low-bicarbonate dentifrice had much less effect.

Journal - Compendium of continuing education in dentistry. (Jamesburg, N.J. : 1995). Supplement (United States )

Abstract :

Because many factors influence the acid-forming ability of dental plaque in the mouth, a model system was used in which reproducible Stephan curves could be generated after exposure of a gel-stabilized plaque to sucrose. Simulation of the use of a high-bicarbonate dentifrice at a time when plaque pH had fallen to about 4.5 caused a rapid return of the pH toward neutrality, whereas simulation of the use of a low-bicarbonate dentifrice had much less effect.

Journal - The New Zealand dental journal (NEW ZEALAND )

Abstract :

This paper discusses the different types of calcium phosphate in calculus and the role of plaque pH in controlling calcium phosphate precipitation (calculus) or dissolution (caries). There is great site-specificity of deposition of supragingival but not subgingival calculus, with highest amounts of the former being present on the lingual aspects of the mandibular anterior teeth. This may be because the plaque there is most alkaline as that region has the highest salivary film velocity and the lowest salivary sugar concentration during consumption of sugar-containing food and drinks. The importance of calculus removal for good gingival health is emphasised.

Journal - Archives of oral biology (ENGLAND )

Abstract :

On two occasions, 12 adults collected unstimulated saliva and then eight samples of saliva over a 20-min period while chewing 3 g of either Wrigley's Spearmint sucrose-containing gum (SCG) or sugar-free gum (SFG) at 70 chews/min. The flow rates peaked initially, then fell with duration of stimulation. With the SFG they were slightly but significantly higher than with the SCG after 4 min of chewing. The sum of the concentrations of cations minus the sum of the concentrations of anions was not significantly different from zero for saliva elicited by the SCG. However, for unstimulated saliva and that elicited by SFG, there was a slight positive anion balance. A second series of saliva collections with SCG and SFG was made by the same 12 participants and these samples were analysed for lactate. For these collections the flow rates with SCG were not significantly less than with the SFG. The lactate concentration in saliva elicited by SCG peaked at 1.82 mmol/l in samples collected over 8-15 min, whereas samples of saliva elicited by SFG had a mean lactate concentration of 0.21 mmol/l. Of the lactate formed during the metabolism of sucrose by the oral bacteria, only 2% or less appeared to be derived from the metabolism of micro-organisms free in saliva, the balance presumably being formed in dental plaque and entering the saliva by diffusion. All saliva samples were supersaturated with respect to hydroxyapatite but stimulated saliva was significantly more supersaturated than unstimulated saliva.(ABSTRACT TRUNCATED AT 250 WORDS)

Journal - Journal of dental research (UNITED STATES )

Journal - Annals of the New York Academy of Sciences (UNITED STATES )

Journal - Journal of dental research (UNITED STATES )

Abstract :

Over a 20-minute period, subjects expectorated 8 samples of whole saliva (EWS) while chewing gum. Flow rates were calculated, and sucrose was analyzed in these samples as well as in saliva collected on filter paper strips from different tooth surfaces. Salivary film velocity (SFV), based on a 0.1-mm-thick film, was estimated from the clearance half-times of KCl in agarose disks positioned in different regions of the mouth. Salivary flow rate peaked at 5.1 mL/min in the first min but fell to about 1.25 mL/min by the end of the 20 min of gum-chewing. In contrast, flow rate when subjects sucked sour lemon drops averaged about 5.3 mL/min throughout the 20-minute period. The mean salivary sucrose concentration during gum-chewing peaked in the second min at 384 mmol/L (13.1%) but had fallen to 14 mmol/L by the 15-20-minute time interval. The sucrose concentrations on the palatal surfaces of the upper incisors and the facial and lingual surfaces of the lower molars were not significantly different from that in EWS but were much lower on the facial surfaces of the upper incisors and molars, and on the lingual surfaces of the lower incisors. When flow was unstimulated, SFV was 0.8-1.0 mm/min on the facial surfaces of the upper incisors and lower molars but about 5-8 mm/min on the facial surfaces of the upper molars and on the lingual surfaces of the lower incisors and molars.(ABSTRACT TRUNCATED AT 250 WORDS)

Journal - Caries research (SWITZERLAND )

Abstract :

The objectives of this study were to determine how salivary flow rate and pH vary with time during use of chewing-gums and lozenges. Twenty-four young adults collected unstimulated saliva and then, on different occasions, chewed one of six flavoured gums, or gum base, or sucked on one of two lozenges, for 20 min, during which time eight separate saliva samples were collected. Flow rate peaked during the 1st minute of stimulation with all nine products. With the lozenges, flow rate fell towards the unstimulated rate when the lozenges had dissolved. There were no significant differences in the flow rates elicited by cinnamon- or peppermint-flavoured gums or between sugar-containing or sugar-free gums. With the flavoured gums, the mean flow rate followed a power curve (r = -0.992) with time and within about 10 min was not significantly different from that when gum base was the stimulus. The initial stimulated flow rate with flavoured gums was about 10-12 times greater than the unstimulated rate (0.47 ml/min). After 20 min of chewing, it was still about 2.7 times that rate and about the same as the flow rate elicited by chewing-gum base alone. The pH of unstimulated saliva was about 6.95. With one gum containing about 1.5% organic acids, the salivary pH fell to a minimum of 6.18 in the 1st minute of stimulation, but then rose rapidly to a level above that in unstimulated saliva. With a sucrose-containing and a sucrose-free gum, the pH rose immediately on stimulation and then fell slightly with time to levels which were significantly above the pH of unstimulated saliva.

Journal - Journal of dental research (UNITED STATES )

Abstract :

The normal concentration of fluoride in saliva is about 1 mumol/L, which is somewhat less than that in plasma, and the salivary concentration is relatively independent of flow rate. Even this low concentration appears to be significant in terms of maintaining the integrity of tooth mineral. After fluoride consumption, the level in plasma peaks within less than an hour, and this produces a corresponding increase in salivary levels, which achieve baseline values usually within a few hours. At low concentrations (less than 4 mmol/L) in oral fluids, fluoride undergoes only slight reaction with tooth mineral to form fluorohydroxyapatite. However, at higher concentrations calcium fluoride is formed on the tooth surface. Although this mineral is sparingly soluble in saliva, the process of dissolution is retarded for periods of up to a week or longer by surface deposition of salivary phosphate and pyrophosphate. The rate of clearance of exogenous fluoride from saliva is prolonged when initial concentrations are high, due to the deposition of CaF2 on the tooth surface and its gradual dissolution. The clearance rate is also not constant throughout the mouth, but shows considerable site-specificity. In general, clearance is much more rapid lingually than buccally. This appears to be due to the greater lingual exposure to secretions from the major salivary glands, principally the submandibular, whereas buccally, mainly minor mucous gland secretions are present, and these are very viscous and flow at a slow rate.

Journal - Journal of dental research (UNITED STATES )

Abstract :

Previously, we studied the clearance rates of KCl from agarose gels positioned at different locations in the mouth, and showed that the rates were much slower than when clearance was into a well-stirred solution. We designed the present in vitro study to test the effect on KCl clearance of the velocity of a 0.1-mm-thick film of water flowing over an agarose gel of the same diameter and composition as those used in vivo. The thickness of the salivary film overlying dental plaque has been estimated to be about 0.1 mm, and we assumed that when clearance rates in vitro matched those found in vivo, velocities of the fluid film (in vitro) and the salivary film (in vivo) must be equal. On this basis, it was calculated in the present experiments that when salivary flow was unstimulated, the velocity of the salivary film at the level of the teeth varied between about 0.8 mm/min (upper-anterior buccal region) and 8.0 mm/min (lower-anterior lingual region). When salivary flow was stimulated, this was estimated to increase the velocity of the salivary film from 2 to 40 times, depending on the location in the mouth. It is postulated that the slow movement of the salivary film when flow is unstimulated allows for accumulation of diffusants from dental plaque, which reduces the concentration gradient for diffusion from plaque and prolongs the clearance time of such metabolic products as acid.

Journal - Journal of dental research (UNITED STATES )

Abstract :

Recent studies have indicated that saliva in the mouth is present as a film only about 0.1 mm thick, and that this film moves at different rates (about 0.8 to 7.6 mm/min) in different regions of the oral cavity. The clearance rates of KCl, as a model diffusant, from agarose gels at different sites in the mouth have also been found to vary markedly, and it has been proposed that these variations are related to differences in the velocity of the salivary film. A computer model has been developed for prediction of clearance half-times for substances diffusing from plaque of variable dimensions into a film of fluid 0.1 mm thick, moving at different velocities. The results show that over the range of velocities calculated to occur in the mouth, the clearance half-times are directly related to the length of plaque over which the fluid passes, and inversely related to the salivary film velocity. The predictions of the model are in good agreement with experimental results from a physical model. Tests were made of the predicted effect of salivary film velocity on the shape of the pH curve initiated by exposure of plaque to a saturated sucrose solution, followed by normal salivary clearance. With a low salivary film velocity, the fall in pH was greater and more prolonged.(ABSTRACT TRUNCATED AT 250 WORDS)