Modern methods for assessing the cariogenic and erosive potential of foods

Clinical Evaluation of the Effect of Nanohydroxyapatite Lozenge on the pH of Dental Plaque

Purpose

This study investigated the influence of nanohydroxyapatite-containing (nanoHAP) lozenge on plaque pH following sucrose intake.

Patients and Methods

Sixteen adult subjects were enrolled in this double-blind crossover study composed of four interventions: (1) 10% w/v sucrose solution, (2) 10% w/v sorbitol solution, (3) nanoHAP lozenge, and (4) 10% w/v sucrose solution challenge followed by nanoHAP lozenge. Following the determination of each subject's resting plaque pH, the pH was measured at different time intervals from 3 to 30 minutes from the start of intervention, with 7 days interval between the applications of different interventions. The data were analyzed using the analysis of variance and Tukey's test (α < 0.05).

Results

While sorbitol produces no change in plaque pH, nanoHAP-lozenge increased the plaque pH from a baseline of 7.0 ± 0.3 (mean ± sd) to 7.8 ± 0.2 (mean ± sd) within 30 minutes. Sucrose lowered the plaque pH from a baseline of 7.0 ± 0.4 (mean ± sd) to the lowest minimum of 5.1 ± 0.1 (mean ± sd) at the 7th minute, rising above the critical pH of enamel dissolution (5.5) at 12th minute and the baseline pH in more than 30 minutes. With lozenge intervention following sucrose challenge, plaque pH rose to 5.5 in 8 min, and to the baseline pH in 24 min. The cH area (Hydrogen ion concentration area) produced by sucrose (1.82 sq. units) was significantly (p < 0.05) greater than that produced when sucrose was challenged with lozenge (0.48 sq. units).

Conclusion

Nanohydroxyapatite-containing lozenge increased plaque pH, reduced plaque pH drop in the presence of sucrose, and facilitated the rapid recovery of plaque pH after sucrose intake.

Rinsing with water for 1 min after milk formula increases plaque pH

PURPOSE

Parents find it challenging to follow recommendations to brush young children after feeds at night despite the increase caries risk. This study compared three clinical recommendations (dilution, rinsing and wiping) on plaque pH after formula consumption.

METHODS

Eighteen subjects were recruited. The five interventions with 2-week washout between visits included: Rinse with undiluted formula for 30 s (UF); rinse with 50% diluted formula for 30 s (DF); rinse with undiluted formula for 30 s, followed by rinsing with water for 1 minute (UF/R); rinse with undiluted formula for 30 s, followed by wiping (UF/W); rinse with 10% sucrose for 30 s as control (C). Plaque samples were collected at baseline, 2, 5, 10, 20 and 30 min after the intervention and pH measured using the plaque sampling method.

RESULTS

UF/R resulted in significantly smaller pH drops at 5, 10 and 20 min compared to UF. It also resulted in higher minimum pH (UF/R: 6.34 ± 0.36 Vs UF: 6.06 ± 0.40, p = 0.02), smaller maximum pH drop (UF/R: 0.63 ± 0.35 Vs UF: 0.90 ± 0.49, p = 0.03), smaller sum of change of hydrogen ion concentration (UF/R: 9.22 × 10^-7 ± 7.8 × 10^-7 Vs UF: 2.30 × 10^-6 ± 2.6 × 10^-6, p = 0.04), and smaller area under the curve (UF/R: 7.70 ± 5.44 Vs UF: 13.44 ± 9.44, p = 0.02). DF and UF/W did not result in any significant pH change compared to UF.

CONCLUSIONS

Of the three clinical recommendations, only rinsing with water for 1 min after undiluted formula reduced plaque acidogenicity. Teeth wiping with a moist cloth and 50% dilution of infant formula did not have an effect on plaque acidity.

Anorexia, Oral Health and Antioxidant Salivary System: A Clinical Study on Adult Female Subjects

The aim of this study was to compare the oral health status and salivary antioxidant system between patients diagnosed with anorexia nervosa (AN) and healthy controls. A total of 25 female AN patients and 25 matched healthy controls were enrolled. Clinical parameters and saliva samples were collected for each patient. Two questionnaires to investigate oral health and hygiene were administered. Superoxide Dismutase (SOD) activity and High Reactive Oxygen Species (hROS) were evaluated. Salivary concentration of SOD was significantly higher in subjects with AN compared with control group (1.010 ± 0.462 vs. 0.579 ± 0.296 U/mL; p = 0.0003). No significant differences between groups were identified for hROS (233.72 ± 88.27 vs. 199.49 ± 74.72; p = 0.15). Data from questionnaires indicated that, although most of the patients recognized the oral hygiene importance in maintaining a good oral health, more than half of them had poor oral hygiene. Altered biochemical composition of saliva in patients with AN could be interpreted as an effective defence mechanism against oxidative stress. Moreover, despite the discrepancy between clinical findings and perception of the oral health in AN population arose, the quality of life of these patients appears not to be significantly affected by their dental condition.

New animal model of extrinsic dental erosion-Erosive effect on the mouse molar teeth

OBJECTIVE

Consumption of acidic food and drinks is considered as important risk factor for development of dental erosion. There are several in vitro and in situ studies focusing on the risk indicators and preventive treatment, however, the need for a standardized animal model has been emphasised for many years. The aim was to establish an animal model of extrinsic dental erosion, which may serve as a standard for future studies to improve our understanding of the erosion.

DESIGN

Two acidic drinks, sports drink and cola drink, were given to young mice for six weeks. Experimental and control (water) molars and incisors were dissected out and observed by scanning electron microscopy (SEM). Mandibular first molars were subsequently ground transversely and observed again by SEM. The tooth height and enamel thickness were measured on the SEM images.

RESULTS

The lingual surface of the mandibular molars was most eroded after consumption of acidic drinks. The cola drink exhibited higher erosive effect on mandibular molars compared to sports drink. The lingual tooth height, compared to control, was about 34% and 18% lower in the cola drink and sports drink molars, respectively. Compared to the control molars, the lingual enamel was about 23% thinner in the sports drink molars and totally eroded on the certain lingual areas of the cola drink molars.

CONCLUSIONS

This new animal model of extrinsic dental erosion and the presented method with ground molars observed in SEM are suitable for further studies, which will gain deeper insights into the erosive disease.

Effects of Xylitol and Sucrose Mint Products on Streptococcus mutans Colonization in a Dental Simulator Model

Few laboratory methods exist for evaluating the cariogenicity of food ingredients. In this study, a dental simulator was used to determine the effects of commercial sucrose and xylitol mint products on the adherence and planktonic growth of Streptococcus mutans. Solutions (3% w/v) of sucrose, xylitol, sucrose mints, xylitol mints, xylitol with 0.02% peppermint oil (PO), and 0.02% PO alone were used to test the levels of planktonic and adhered S. mutans. A dental simulator with continuous artificial saliva flow, constant temperature, and mixing was used as a test environment and hydroxyapatite (HA) discs were implemented into the model to simulate the tooth surface. Bacterial content was quantified by qPCR. Compared with the artificial saliva alone, sucrose and sucrose mints increased the numbers of HA-attached S. mutans, whereas xylitol decreased them. Similarly, planktonic S. mutans quantities rose with sucrose and declined with xylitol and xylitol mints. Versus sucrose mints, xylitol mints significantly reduced the counts of HA-bound and planktonic S. mutans. Similar results were observed with the main ingredients of both types of mints separately. PO-supplemented artificial saliva did not influence the numbers of S. mutans that attached to HA or planktonic S. mutans compared with artificial saliva control. In our dental simulator model, xylitol reduced the counts of adhering and planktonic S.mutans. The mints behaved similarly as their pure, main ingredients-sucrose or xylitol, respectively. PO, which has been suggested to have antimicrobial properties, did not influence S. mutans colonization.

Effect on oral pH changes and taste perception in 10-14-year-old children, after calcium fortification of a fruit juice

AIM

The aim was to determine the effect of calcium fortification of a commercially available mixed-fruit juice on oral pH changes and taste perception in a group of 10 to 14 year-old Indian children.

METHOD

A controlled, blinded, non-randomised clinical trial was adopted, consisting of a sample of 100 healthy children (DMFT <3; age 10-14 years), who were exposed to three test juices one by one [Group A: original fruit juice (control group); Group B: calcium-fortified fruit juice and Group C: calcium + vitamin D fortified fruit juice]. Oral pH, collection of saliva and plaque sampling was undertaken, before and after the juice exposure by each subject at 0, 1, 5, 15, 30 and 45 min. The respective pH was measured with a digital pH meter. For taste perception, a scoring system was used after exposure of the juices to the subjects in a blind manner. The statistical evaluation was done using one-way ANOVA for salivary and plaque pH and Kruskal-Wallis test for buffer capacity and taste perception.

RESULTS

There was a smaller drop in salivary and plaque pH (p < 0.5) and a significant reduction in perceived taste (p < 0.001) by the subjects after calcium modification of fruit juice.

CONCLUSION

The calcium-modified mixed fruit juices was less acidogenic compared with the unfortified juice, and hence will be less cariogenic and erosive towards teeth.

Sugar industry influence on the scientific agenda of the National Institute of Dental Research's 1971 National Caries Program: a historical analysis of internal documents

BACKGROUND

In 1966, the National Institute of Dental Research (NIDR) began planning a targeted research program to identify interventions for widespread application to eradicate dental caries (tooth decay) within a decade. In 1971, the NIDR launched the National Caries Program (NCP). The objective of this paper is to explore the sugar industry's interaction with the NIDR to alter the research priorities of the NIDR NCP.

METHODS AND FINDINGS

We used internal cane and beet sugar industry documents from 1959 to 1971 to analyze industry actions related to setting research priorities for the NCP. The sugar industry could not deny the role of sucrose in dental caries given the scientific evidence. They therefore adopted a strategy to deflect attention to public health interventions that would reduce the harms of sugar consumption rather than restricting intake. Industry tactics included the following: funding research in collaboration with allied food industries on enzymes to break up dental plaque and a vaccine against tooth decay with questionable potential for widespread application, cultivation of relationships with the NIDR leadership, consulting of members on an NIDR expert panel, and submission of a report to the NIDR that became the foundation of the first request for proposals issued for the NCP. Seventy-eight percent of the sugar industry submission was incorporated into the NIDR's call for research applications. Research that could have been harmful to sugar industry interests was omitted from priorities identified at the launch of the NCP. Limitations are that this analysis relies on one source of sugar industry documents and that we could not interview key actors.

CONCLUSIONS

The NCP was a missed opportunity to develop a scientific understanding of how to restrict sugar consumption to prevent tooth decay. A key factor was the alignment of research agendas between the NIDR and the sugar industry. This historical example illustrates how industry protects itself from potentially damaging research, which can inform policy makers today. Industry opposition to current policy proposals-including a World Health Organization guideline on sugars proposed in 2014 and changes to the nutrition facts panel on packaged food in the US proposed in 2014 by the US Food and Drug Administration-should be carefully scrutinized to ensure that industry interests do not supersede public health goals.

The effect of recommending a CPP-ACPF product on salivary and plaque pH levels in orthodontic patients: a randomized cross-over clinical trial

OBJECTIVE

Along with their re-mineralizing capacity, calcium phosphopeptide-amorphous calcium phosphate products combined with fluoride (CPP-ACPF) could also be beneficial by neutralizing acidic salivary and plaque pH. The purpose was to evaluate the effect of CPP-ACPF on salivary and plaque pH in orthodontic patients.

MATERIALS AND METHODS

As a triple-blind, cross-over randomized trial, 30 orthodontic patients with fixed appliances (age range = 15.70 ± 4.08 years) were recruited and randomly assigned to two groups. A CPP-ACPF paste (MI Paste Plus, GC America, Alsip, IL) was used by group 1 (n = 15) and a placebo by group 2 (n = 15) for 1 month. After a 1 month washout period, patients used the alternative paste for another month. Plaque and salivary pH levels were measured at all before and after periods.

RESULTS

By applying MI Paste Plus, the plaque pH increased from 5.81 ± 0.45 to 6.60 ± 0.38 (p < 0.05), whereas the before and after salivary pH recordings, which were 6.72 ± 0.43 and 6.71 ± 0.38, respectively, remained statistically unchanged (p > 0.05).

CONCLUSION

MI Paste Plus can be clinically beneficial in increasing plaque pH levels, but has no effect on the salivary pH.

Effect of honey in preventing gingivitis and dental caries in patients undergoing orthodontic treatment

OBJECTIVES

THIS STUDY WAS CONDUCTED TO INVESTIGATE THE FOLLOWING: (1) the effects of chewing honey on plaque formation in orthodontic patients, (2) the effect of chewing honey on dental plaque bacterial counts, (3) determine if honey possesses antibacterial effects on bacteria recovered from plaques.

METHODS

Female orthodontic patients (n = 20, 12-18 years of age) participated in this randomized controlled study. The effects of honey were compared to treatment with either 10% sucrose or 10% sorbitol that served as positive and negative controls, respectively. The pH of plaque was measured using a digital pH meter prior to baseline and at 2, 5, 10, 20, and 30 min after chewing honey or rinsing with control solutions and the numbers of Streptococcus mutans, Lactobacilli, and Prophymonas gingivalis in respective plaques were determined. The antibacterial activity of honey was tested against commonly used antibiotics using the disk diffusion method.

RESULTS

Significant differences in pH were observed in the honey and sucrose groups compared to the pH observed in the sorbitol group (p ⩽ 0.001). The maximum pH drop occurred at 5 min in both the honey and sucrose groups; however the pH in the honey group rapidly recovered 10-20 min after exposure and did not drop below the critical decalcification pH of 5.5. On the other hand, the pH following sucrose exposure fell <5.5 and was associated with a 30 min recovery time. The pH observed for the sorbitol group did not change over time. Bacterial counts were significantly reduced in the honey group compared to the other treatment groups (p ⩽ 0.001) and honey significantly inhibited the growth of all studied strains compared to inhibition observed with antibiotics (p ⩽ 0.001).

CONCLUSIONS

Honey can be used as an alternative to traditional remedies for the prevention of dental caries and gingivitis following orthodontic treatment.

In vitro inhibition of bovine enamel demineralization by enamel matrix derivative

This study aimed to determine whether enamel matrix derivative (Emdogain) affects the demineralization of bovine enamel in vitro and to assess the agent's anti-caries potential. Bovine enamel blocks were prepared and randomly divided into three groups (n = 15 per group), which were treated with distilled water (negative control), NaF (positive control), or Emdogain. All three groups were pH-cycled 12 times over 6 days. The percentage of surface enamel microhardness reduction (%SMHR), calcium demineralization rate (CDR), surface roughness, lesion depth and mineral loss after demineralization were examined. Surface morphology of specimens was studied by scanning electron microscopy. The Emdogain and positive control groups showed similar surface roughness, lesion depths and mineral loss, which were significantly lower than those in the negative control group. In addition, the enamel surfaces of both the Emdogain and NaF groups showed much narrower intercrystalline spaces than the surfaces of the negative control group, which exhibited extensive microfractures along the crystal edges. %SMHR differed significantly among all three groups, with the smallest value in the Emdogain group and the greatest in the negative control group. These results indicate that enamel matrix derivative (Emdogain) can significantly inhibit demineralization of bovine enamel in vitro, suggesting that it has potential as an anti-caries agent.

Soft drinks and dental health: a review of the current literature

In recent years there has been increased interest in the role of commercial soft drinks in dental diseases namely as dental caries and erosion. The objective of this paper has been to review the past and current literature to determine the present knowledge on this subject. The literature related to dental caries, erosion, drinks, soft drinks and fruit juices was reviewed. The literature shows efforts have been taken to modify soft drinks by either adding or deleting certain components so as to reduce their harmful effects on teeth. A rational protocol to encourage the sensible use of drinks and the modification of drinks to render them less harmful would be advisable.

Method to Detect Minimal Amounts of Calcium Dissolved in Acidic Solutions

The study describes the application of the Arsenazo III method for detection of minimal amounts of calcium 12.4-49.4 micromol/l in different acidic solutions (hydrochloric acid, oxalic acid, maleic acid, phosphoric acid, tartaric acid, citric acid, lactic acid and acetic acid) adjusted to pH 2.0, 2.3 and 3.0. A mixture of the respective calcium concentrations with distilled water served as control. The experiments were run with ten repeats in series. Assessment of intra- and interassay coefficient of variation, and lower limit of quantification revealed that depending on the acid used, the Arsenazo III method is a reliable tool to quantify minimal calcium contents in acidic solutions.

Suitability of a malachite green procedure to detect minimal amounts of phosphate dissolved in acidic solutions

The study describes the suitability of a colorimetric method (malachite green procedure) for detection of minimal amounts of phosphate (7.3-29.1 micromol/L) in different acidic solutions (hydrochloric acid, oxalic acid, maleic acid, perchloric acid, tartaric acid, citric acid, lactic acid and acetic acid) adjusted to pH 2.0. A mixture of the respective phosphate concentrations with distilled water served as control. The experiments were run with ten repeats in series. Assessment of intra- and interassay coefficient of variation and lower limit of quantification revealed that depending on the acid used, the applied method is a reliable and suitable tool to detect and quantify minimal phosphate contents in small samples of acidic solutions that have the potential to cause erosive dental lesions.

Developments in dental plaque pH modelling

OBJECTIVES

The objectives of this review were to give a comprehensive account of the methods used to determine dental plaque pH over the last 50 years, to review how these methods have been used in dental cariology research and to give an update as to how dental plaque pH studies might be developed in the future.

DATA

Published, referred papers and abstracts of conference proceedings in the literature were reviewed.

SOURCES

A comprehensive search of the electronic databases PubMed and Medline, was undertaken. In addition, a hand search of the Index Denticus was done to identify relevant citations before 1966.

STUDY SELECTION

Relevant published literature in peer-reviewed publications was reviewed. No additional inclusion criteria were applied.

CONCLUSIONS

This comprehensive review gives an account of the background to, history of, relative merits and demerits of, applications of and future of dental plaque pH technologies.

Modification of soft drinks with xanthan gum to minimise erosion: a study in situ

OBJECTIVE

To compare the erosive effect of a new blackcurrant/calcium drink with xanthan gum, on enamel in situ, with a low erosive product, a conventional fruit beverage and water.

DESIGN

The study was single centre, randomised, single blind, 4 treatment crossover design.

SETTING

This study, conducted in 2000, employed volunteers working at the Bristol Dental Hospital, UK.

SUBJECTS, MATERIALS AND METHODS

16 subjects (>or=18 years) wore two enamel samples in a removable acrylic appliance. The drinks tested were (A) New blackcurrant/calcium/gum drink (test product), (B) Original blackcurrant/calcium drink, (C) Conventional blackcurrant drink (positive control) and (D) Water (negative control), for 15 day study periods. Drinking was supervised, with 250 ml imbibed four times/day between 9.00am-5.00pm. Profile measurements of specimens were made at baseline, 5, 10 and 15 days.

MAIN OUTCOME MEASURES

Paired t-tests compared erosion by surfometry with selected pairs of formulations.

RESULTS

Of 16 screened subjects (3 male, 13 female), mean age 34.2 years, 1 subject failed to complete the study. A caused significantly less enamel loss than C, with no statistically significant differences from B at any time points measured. Of 43 treatment emergent adverse events, none were considered related to the study formulations.

CONCLUSIONS

A retained low erosive properties similar to B, with additional benefits of taste flexibility and beverage stability.

Effect of mineral supplements to citric acid on enamel erosion

The aim of this study was to evaluate the effect of mineral supplements to citric acid (1%; pH 2.21) on enamel erosion under controlled conditions in an artificial mouth. From each of 156 bovine incisors one polished enamel sample was prepared. The samples were divided among 13 experimental groups (n=12). In group 1 citric acid only was used (control). In groups 2-10 either calcium, phosphate or fluoride in various low concentrations was admixed to the citric acid. In groups 11-13 the citric acid was supplemented with a mixture of calcium, phosphate and fluoride. For demineralisation the specimens were rinsed with the respective solution for 1 min, immediately followed by a remineralisation period with artificial saliva (1 min). The specimens were cycled through this alternating procedure five times followed by rinsing for 8 h with artificial saliva. The de- and remineralisation cycle was repeated three times for each specimen interrupted by the 8 h-remineralisation periods. Before and after the experiments, the specimens were examined using microhardness testing (Knoop hardness) and laser profilometry. Hardness loss and enamel dissolution was significantly higher for the controls as compared to the remaining groups. Significantly lowest hardness loss for all groups was recorded for group 12 with admixture of calcium, phosphate and fluoride to citric acid. The significantly highest enamel loss was recorded for the controls compared to all other samples. Groups 3 and 4 revealed significantly lower and higher tissue loss compared to the remaining groups (2-13), respectively. The other groups did not differ significantly from each other. Modification of citric acid with calcium, phosphate and fluoride exerts a significant protective potential with respect to dental erosion. However, with the low concentrations applied enamel dissolution could not be completely prevented.

The erosive potential of commercially available mouthrinses on enamel as measured by Quantitative Light-induced Fluorescence (QLF)

DESIGN

Longitudinal in vitro.

METHODS

Previously extracted, caries free, human premolars were selected and prepared by gentle pumicing and coating in an acid-resistant nail-varnish save for an exposed enamel window on the buccal surface. Each was assigned to one of eight groups (six per group, 10 in positive control); positive control (citric acid, pH 2.7, F(-) 0 ppm), negative control (pH 7.0, F(-) 0 ppm) Listerine (pH 3.87, F(-) 0.021 ppm), Tesco Value (pH 6.05, F(-) 289.00 ppm), Tesco Total Care (pH 6.20, F(-) 313.84 ppm), Sainsbury's (pH 6.15, F(-) 365.75 ppm), Sensodyne (pH 6.12, F(-) 285.30 ppm) and Corsodyl (pH 5.65, F(-) 0 ppm). The titratable acid values (TAV) for each rinse were established using volume (ml) of 0.1 M NaOH to achieve pH 7. Fluoride values were obtained by ion selective electrode. The solutions were kept at 37 degrees C and gently agitated. Teeth were removed at hourly intervals for 15 h, air-dried and subjected to Quantitative Light-induced Fluorescence (QLF) examination by a blinded examiner and DeltaQ values recorded. At the conclusion of the study each of the positive control teeth and one from each other group were sectioned through the eroded lesion, ground and polished to 100 micrometers and subjected to transverse microradiography and DeltaZ recorded for validation.

RESULTS

TAVs were: Listerine 2.45 L > Sainsbury's 0.35 ml >Tesco Total Care 0.14 ml > Tesco Value 0.08 ml > Corsodyl 0.10 ml >Sensodyne 0.9 ml. DeltaQ increased over time for the positive control, (0 h 0.2, 10 h 95.2, 15 h 152.3). Negative controls remained stable. The increase in DeltaQ for each rinse after 15 h was Listerine (9.3(+/-7.2)), Corsodyl (1.5(+/-1.2)), Tesco Value (1.8(+/-1.2)), Tesco Total Care (1.4(+/-1.1)), Sainsbury's (3.4(+/-2.2)), Sensodyne (0.9(+/-1.6)). TMR confirmed the presence/absence of erosive lesions.

CONCLUSIONS

QLF effectively monitored erosion in the positive controls and lack of erosion in the NC. Only one mouthrinse (Listerine) caused any erosion compared to the negative control, but this was only significant after 14 h of continuous use.