Effects of milk on pH of plaque and salivary sediment and the oral clearance of milk

The effects of beverages on plaque acidogenicity after a sugary challenge

BACKGROUND

Caries prevention traditionally has emphasized the restriction of cariogenic foods and beverages, but it has placed less emphasis on how the choice, combination and sequence of consumed foods and beverages may help reduce plaque acidogenicity. The authors conducted a study to examine whether whole milk, 100 percent apple juice or tap water affect dental plaque acidity in people after a sugary challenge.

METHODS

Twenty adults participated in a randomized controlled crossover study. Participants consumed four combinations of foods: 20 grams of dry sugary Froot Loops (FL) (Kellogg's, Battle Creek, Mich.) cereal, 20 g of FL followed by 50 milliliters of milk (FL/milk), 20 g of FL followed by 50 mL of juice (FL/juice) and 20 g of FL followed by 50 mL of water (FL/water). The authors used a touch microelectrode to take plaque pH readings at the interproximal space just below the contact area between the maxillary premolars on both left and right sides at two and five minutes after FL consumption and at two to 30 minutes after milk, juice or water consumption.

RESULTS

Consumption of FL plaque pH (standard deviation [SD]) was 5.83 (0.68) at 30 minutes, whereas plaque pH (SD) in the FL/milk group was 6.48 (0.30), which was significantly higher than that for FL/juice (5.83 [0.49]) or FL/water (6.02 [0.41]) (P < .005) at 35 minutes.

CONCLUSION

Drinking milk after a sugary cereal challenge significantly reduced plaque pH drop due to the sugary challenge.

PRACTICAL IMPLICATIONS

When discussing the cariogenicity of foods and beverages with patients, dentists and other health care professionals should emphasize that the order of ingesting sugary and nonsugary foods is important and may affect their oral health.

The effect of different milk formulas on dental plaque pH

OBJECTIVES

The purposes of this study were (1) to investigate the effect of different milk formulas on dental plaque pH after rinsing with these three categories, type of protein-based formulas (milk-based, soy-based, protein hydrolysate), type of sugar (only lactose, lactose and other sugars, only non-milk extrinsic sugars), and casein ratio (high and low casein), and (2) to observe organic acids formed by different milk formulas.

METHODS

Baseline plaque pH and plaque pH at 2, 5, 10, 15, 20, 25, 30, and 60 min after rinsing with milk formulas were recorded by a combination electrode in 14 healthy subjects. Deionized water and 10% sucrose were used as a negative and positive control. The plaque sample was also analysed to identify and quantify the organic acids using a high-performance liquid chromatography. Parameters including minimum pH, maximum pH drop, and area under curve were compared by RMANOVA and paired t-test.

RESULTS

The minimum pH was not significantly different among different protein-based formulas, whereas, the maximum plaque pH drop of soy-based and milk-based formula was significantly higher than that produced by protein hydrolysate formula (P=0.022 and 0.03, respectively). Area under curve produced by soy-based and milk-based formulas was significantly larger than that created by protein hydrolysate formula (P=0.025 and<0.001, respectively). Milk formulas containing only lactose caused significantly less plaque pH change in minimum pH (P<0.001), maximum pH drop (P=0.003), and area under curve (P<0.001) when compared with formulas containing lactose and other sugar but not with special formulas containing only non-milk extrinsic sugar. Similarly, special formulas containing non-milk extrinsic sugar produced significantly lower minimum pH and smaller area under curve than formulas containing lactose and other sugar did (P=0.044 and 0.009, respectively). No different results were found between high and low casein follow-on formulas. Lactic acid was produced more by rinsing with formulas containing lactose and other sugars than that produced by formulas containing only lactose.

CONCLUSIONS

This study suggests that milk formulas containing added other sugars tend to cause a decrease in plaque pH.

Effect of fluoridated milk on caries in primary teeth: 21-month results

OBJECTIVES

Use of fluoridated milk has been shown to be a safe and effective method to prevent caries in permanent teeth in children. However, studies on its effectiveness on caries prevention in the primary teeth are scarce. The purpose of the present study was to evaluate the effect of milk fluoridation on caries development in young Chinese children.

METHODS

This was a community-based demonstration study carried out in Beijing, China. All children in three selected kindergartens were invited to participate. Each participant consumed 200 ml of fluoridated milk (concentration 2.5 mg F- per litre) per day from Monday to Friday in the kindergarten, and was given two packs of fluoridated milk (250 ml) for consumption at home on Saturday and Sunday every week. Children from a similar background, but without access to fluoridated milk, attending two other kindergartens, were used as the control.

RESULTS

There were 534 children (mean age 54 +/- 4 months) and 305 children (mean age 53 +/- 4 months) in the test and control groups, respectively, at baseline. After 21 months, 417 and 247 children in the test and control groups, respectively, remained in the study. There was no statistically significant difference in the baseline mean dmft scores between the two groups (3.2 vs. 3.5, P = 0.312). After 21 months, the mean net caries increment was 0.4 dmft for the test group and 1.3 dmft for the control group (t-test, P < 0.001).

CONCLUSION

The consumption of fluoridated milk by the kindergarten children in Beijing was an effective measure in preventing caries in the primary teeth.

Risk indicators for tooth wear in New Zealand school children

AIM

To investigate the prevalence and severity of tooth wear in the primary dentition of a representative sample of New Zealand school children and relate these to possible risk factors.

DESIGN

A cross-sectional study.

SETTING

Primary schools in Dunedin, New Zealand.

PARTICIPANTS

104 children of both sexes, aged between 5 and 8 years, randomly selected.

METHODS

Clinical examinations of the buccal, occlusal/incisal and lingual surfaces of deciduous canines and molars.

MAIN OUTCOME MEASURE

Degree of wear and the presence of dentinal cupping of teeth. Information on weaning and consumption of fruit-based drinks at bed time, frequency of consumption of fruits, yoghurt, pickled foods, fizzy and fruit-based drinks.

RESULTS

The prevalence of tooth wear was similar in boys and girls and there were no significant differences between sides of the arches. A high percentage (82%) of children had at least one primary tooth with dentine exposed. While maxillary canines showed the greatest prevalence of dentine exposed, maxillary molars displayed the greatest prevalence of cupping. Severe tooth wear was less prevalent among children weaned after 12 months (14.3%) than those weaned earlier (27.9% P < 0.01). There were no statistically significant associations between wear and the consumption of fruit, yoghurt, pickled foods, fizzy drinks or fruit-based drinks.

CONCLUSIONS

Tooth wear associated with dentine exposure is common in 5-8 year old children. This is not significantly associated with dietary factors, but appears to be related to early weaning from the breast.

An evaluation of the acidogenic potential of maltodextrins in vivo

Maltodextrins are a group of oligosaccharides, which are being increasingly used as a source of carbohydrate in many commercially available foods and drinks. This study investigated the effect of three different maltodextrins on the pH of dental plaque, in vivo, in 10 adult volunteers using the plaque harvesting method. The three maltodextrins tested in this study were DE=5.5, 14.0 and 18.5 (DE=dextrose equivalents), made up as 10% solutions. Also, three commercially available maltodextrin containing children's drinks were evaluated for their acidogenicity. 10% sucrose and 10% sorbitol solutions were used as positive and negative controls, respectively. The minimum pH achieved for DE=5.5, 14.0 and 18.5 was 5.83+/-0.30, 5.67+/-0.24 and 5.71+/-0.29, respectively, and were significantly higher as compared with that for 10% sucrose (5.33+/-0.17). The area under the curve was the least for DE=5.5 (12.03+/-4.64), followed by DE=18.5 (13.13+/-8.87) and DE=14.0 (17.35+/-6.43), but were all significantly smaller as compared with 10% sucrose (24.50+/-8.64). The minimum pH achieved for the infant drinks was 6.01+/-0.24, 5.99+/-0.28 and 5.8+/-0.19 for the Lemon Barley and Camomile Herbal baby drink, Mixed Citrus and Hibiscus baby drink, and Infant Milk, respectively. It was concluded that though maltodextrins appeared to be significantly less acidogenic than 10% sucrose, they can lead to a substantial drop in plaque pH and may, therefore, have a potential to cause demineralisation of enamel.

Milk, flavoured milk products and caries

The consumption of flavoured milk increased by 50% between 1992 and 1999 and dental health educators need to know if these and other sugar and fruit juice sweetened milk products, such as fruit yoghurts, are acceptable as snack items. Available evidence suggests that their cariogenicity is negligible to low and consumed in moderation they are a preferable alternative to similarly sweetened soft drinks.

Biological mechanisms of early childhood caries

The present paper reviews biological issues in early childhood caries (ECC) in light of the current understanding of the field. Despite the general global decline in dental caries in the past decades, ECC has become a significant problem in many developing countries and some minority communities in western industrialized nations. Like other types of caries, ECC is caused by mutans streptococci that ferment dietary carbohydrates to produce acid attacks on susceptible teeth over a period of time. However, while the general etiology of ECC appears similar to that of other types of caries, the predisposing factors are still unclear. The biology of ECC may be modified by several factors unique to young children, related to the implantation of cariogenic bacteria, immaturity of the host defense systems, as well as behavioral patterns associated with feeding and oral hygiene in early childhood.

The relationship between bottle usage/content, age, and number of teeth with mutans streptococci colonization in 6-24-month-old children

OBJECTIVES

Mutans streptococci (MS) are the primary pathogens involved in the development of early childhood caries. However, factors that may affect their acquisition in the mouths of young children are not well understood, and the period of initial colonization remains controversial. This study investigated the relationship of age, number of teeth, and bottle usage/content with regard to the isolation of MS in 6-24-month-old children.

METHODS

A total of 122 children from low-income families attending a nutritional supplement program, and their mothers, participated in this study. Children were examined for dental caries and number of erupted teeth and were sampled for MS. Mothers were administered a questionnaire to obtain details of baby bottle use, including what food items were put in the bottle during the last week.

RESULTS

MS was detected in more than one-third of the 6-24-month-olds. Unlike some studies that suggest a later period of infectivity, approximately 20% of children under 14 months of age, including 4 of 22 infants aged 6-9 months, were colonized with MS. When examined separately, age, number of teeth, and bottle usage/content were each found to be related to the presence of MS. Mutans streptococci colonization was more likely with increasing age and number of teeth, and children whose bottles contained sweetened beverages were more likely to be colonized than children whose bottles contained milk. Logistic regression models that controlled for both age and number of teeth indicated that children who consumed sweetened beverages in their baby bottle had a statistically significant, four-fold increase in the odds of colonization by MS relative to children who consumed milk.

CONCLUSIONS

The finding that approximately 20% of the children under 14 months of age were infected with MS indicates that colonization in this sample of low-income preschool children may begin earlier than suggested by some investigations. Additionally, the risk of MS colonization appears lower among infants who consume milk rather than sweetened beverages in the bottle.

The effect of milk and sucrose consumption on caries in 6-to-11-year-old Italian schoolchildren

The effect of milk on dental caries was studied on a sample of 6-to-11-year-old Italian schoolchildren. The daily amount of milk consumed and the frequency of consumption of sucrose-containing foods were obtained by a 24-hour dietary diary. In the subsequent oral examination, the level of visible plaque and the number of decayed, extracted and filled teeth (both primary and permanent) of the children were recorded. 439 children (217 boys) who did not use fluoride prophylaxis and with poor oral hygiene were selected from among 890 children. They were divided into three groups according to the frequency of sucrose consumption. The data were statistically analysed using multiple logistic regression. The children consumed a daily average of 209 +/- 133 ml of milk and there were no differences among the three groups in this respect. As expected, the dental health of the children with low sucrose frequency was significantly better than that of the children with high sucrose frequency. The regression on the whole sample showed a weak, significant, negative association between milk consumption and caries (p < 0.05). In the group of high sucrose-consuming children a negative, highly significant association was found (p < 0.001), while in the two groups of low and moderate sucrose-consuming children no association was found. These data suggest that, in the present sample of children who did not use fluoride and with poor oral hygiene, milk has a caries preventive effect only on those subjects with a high daily sucrose-consuming frequency.

Effect of buccal administration of a lactose-containing nitroglycerin tablet (Suscard) on plaque pH

The aim of this study was to monitor pH in 2-day-old dental plaque after administration of a long-acting, lactose-containing nitroglycerin tablet (Suscard). The tablet was placed under the lip of the maxilla. This was done both in two older subjects suffering from heart problems and in 10 younger, healthy subjects. In the latter group, a sucrose-containing lozenge was used as a control. The influence of a 5-wk period of daily use of Suscard (in the two elderly subjects) and the effect of normal oral hygiene procedures (in the 10 younger subjects) on the pH response was also studied. Plaque pH was measured in situ up to 1 h, at five different approximal sites in the front region of the maxilla by the micro-touch method. The Suscard tablet resulted in a fall in plaque pH in both groups when teeth had not been brushed for 2 days. The lowest pH was recorded at the sites close to where the tablet had been placed. The most attenuated pH drop was found in the two older subjects, who showed a mean minimum pH of 5.7, as compared with 6.2 for the younger subjects. No further increase in the pH fall from Suscard was seen after the 5-wk period in the two patients with heart problems. In the 10 younger healthy subjects, the most pronounced pH decrease was registered after administration of the sucrose-containing lozenge. The pH drop for Suscard was not significant when normal oral hygiene procedures preceded the test.(ABSTRACT TRUNCATED AT 250 WORDS)

The use of milk as a saliva substitute

Xerostomia, a clinical manifestation of salivary gland dysfunction, affects many people. These individuals frequently sip liquids to alleviate the discomforts associated with hyposalivation. Milk appears to have many of the chemical and physical properties of a good saliva substitute. Besides the obvious benefit of providing moisture and lubrication for the dehydrated mucosa, milk buffers oral acids, reduces enamel solubility, and contributes to enamel remineralization. These anticariogenic factors are generally attributed to the high calcium and phosphate content along with the milk phosphoproteins that strongly adsorb to enamel. Patients with xerostomia frequently have difficulty in obtaining proper nutrition due to problems associated with lubricating, masticating, tasting, and swallowing food. Milk is a food with high nutritional quality that would certainly benefit most patients with xerostomia. Because of the nutritional, anticariogenic, and moisturizing properties of milk, patients with xerostomia may find milk of value as a saliva substitute to help reduce the oral health problems associated with hyposalivation.

Comparison of the effects of galactose and glucose on the pH responses of human dental plaque, salivary sediment and pure cultures of oral bacteria

Comparisons made in dental plaque in vivo demonstrated that galactose produces a significantly smaller decrease in pH than does glucose. In vitro studies with plaque, salivary sediment and pure cultures of oral bacteria done in the absence of intraoral factors such as flowing saliva confirmed this lesser acidogenicity of galactose. Pure culture showed that most of the bacteria tested produce a moderate to large decrease with glucose but only a few do so with galactose; most produced a moderate to little or no pH response with this sugar. This suggested that the smaller decreases in pH seen in plaque in vivo with galactose were largely due to bacterial differences, basically that resident micro-organisms individually have less galactolytic than glucolytic capability. Variance in capability was attributed to differences in membrane transport processes and metabolic pathways normally available to bacteria for galactose and glucose catabolism. In the in vitro experiments, because plaque and sediment can produce base as readily as they can produce acid, the nitrogenous substrates identified earlier as major stimulants of base formation, urea and arginine, were concurrently examined for their attenuating effects on the galactose and glucose pH responses. These showed, consistent with its lesser acidogenicity, that galactose could be countered more readily in its ability to reduce the pH by either of these two base-forming substrates than could glucose. The effects were different with urea and with arginine, urea attenuation occurred sooner and arginine attenuation later in both plaque and sediment. The corresponding acid-base pH profiles for pure cultures were different.(ABSTRACT TRUNCATED AT 250 WORDS)

The acidogenic potential of reference foods and snacks at interproximal sites in the human dentition

Telemetry was used to evaluate changes in plaque pH at interproximal sites in the dentition of five human subjects following the ingestion of a variety of reference foods and snacks. Short-term telemetry (30 min) revealed that most of the substrates yielded both pH minima and total responses similar to that obtained with a 10% sucrose rinse. Aged Cheddar cheese and skim milk were much less acidogenic than were the other foods.

Comparison of methods for monitoring changes in the pH of human dental plaque

Changes in human dental plaque pH can be used to obtain estimates of the acidogenic potential of ingested foods. The presence of acid in plaque is influenced by a large number of host, microbial, and substrate factors. Several useful methods have been developed for monitoring changes in plaque pH. Plaque sampling involves repeated removal of small samples of plaque from a number of teeth at intervals after food ingestion, dispersion of the sample, and in vitro measurement of pH. Touch electrode methods utilize glass or antimony microelectrodes, which are placed onto plaque in situ where direct readings can be obtained. Telemetry methods involve placement of glass microelectrodes or ion-sensitive field effect transistors within the dentition. Plaque is allowed to accumulate, and pH changes can subsequently be transmitted with radio or wire. Each of the methods has clear advantages and limitations. The methods have been simultaneously compared in human volunteers using solutions of fermentable carbohydrate. Inter-method differences in response were observed depending upon the site of measurement. Data obtained from caries-prone surfaces via telemetry showed lower pH minima and retarded returns to resting pH levels. The technology is available for controlled comparative plaque pH studies, with the method of choice depending upon the goals of the investigation. It is essential that the results be compared to data obtained with other models designed to evaluate the cariogenic potential of foods.

Plaque sampling and telemetry for monitoring acid production on human buccal tooth surfaces

The plaque sampling method and wire telemetry using miniature, glass pH electrodes on the buccal surface of mandibular first permanent molars, compared human dental plaque pH responses to a 10 per cent solution of sucrose. Nine subjects abstained from oral hygiene and were tested in morning sessions on 5 consecutive days. The mean resting plaque pH value for all sessions by plaque sampling was 6.60 +/- 0.18 (mean +/- SD) and by telemetry was 6.56 +/- 0.19. After a 1 min sucrose rinse, 1-day-old plaque showed a decrease in pH approx. 5.5 by both methods. The 2-, 3-, 4- and 5-day-old plaque, the mean minimum pH achieved was 4.69 +/- 0.28 as measured by sampling and 3.94 +/- 0.49 as determined by telemetry. The times taken to reach minimum pH as determined by the two methods were almost identical. The electrode calibration data showed that all the telemetry electrodes responded consistently for all 5 days of study. Scanning electron microscopy and microbiological analysis of electrode tips and enamel replicas revealed that plaque accumulated on glass at the same rate with a similar bacterial composition to plaque formed on clean enamel. It is proposed that glass microelectrodes and wire telemetry are a reasonable means for continuously monitoring plaque pH in situ. Comparison with plaque sampling suggested that telemetric responses reflect the type of plaque which accumulates at particular sites on the dentition.