The effect of pH on the erosion of dentine and enamel by dietary acids in vitro

Effect of a Nano-hydroxyapatite Toothpaste on Enamel Erosive Lesions of Third Molars Induced by Exposure to Orange Juice

Objectives

This study aimed to assess the effect of a nano-hydroxyapatite (nano-HA) toothpaste on erosive enamel lesions of third molars induced by exposure to orange juice.

Materials and Methods

In this in vitro, experimental study, the microhardness of 24 sound-extracted third molars was measured by a Vickers tester. The teeth were then randomly assigned to three groups (n = 8) of nano-HA toothpaste (Pharmed), 1.23% sodium fluoride gel, and artificial saliva. The teeth were exposed to orange juice for 5 min daily for 7 days and were then exposed to nano-HA toothpaste, fluoride gel, or artificial saliva (depending on their group allocation) for 10 min a day. The microhardness of the teeth was measured again after 7 days. Data were analyzed using paired t-test, analysis of variance, and Bonferroni test (alpha = 0.05).

Results

Within-group comparisons showed a significant reduction in microhardness of the teeth after the intervention in artificial saliva (P = 0.000), and fluoride gel (P = 0.002) groups. However, no significant reduction occurred in the microhardness of the nano-HA group, compared with the baseline (P = 0.132). Between-group comparisons revealed no significant difference in the microhardness of the three groups at baseline (P > 0.05). However, after the intervention, the microhardness of the nano-HA group was significantly higher than that of other groups (P < 0.05). However, the difference in secondary microhardness between fluoride gel and artificial saliva groups was not significant (P = 1.00).

Conclusion

Pharmed toothpaste containing nano-HA has optimal efficacy for remineralization of enamel erosive lesions induced by exposure to orange juice.

Impact of Dentistry Materials on Chemical Remineralisation/Infiltration versus Salivary Remineralisation of Enamel-In Vitro Study

The aim of this study is to evaluate salivary remineralisation versus chemical remineralisation/infiltration of enamel, using different dentistry materials. The enamel changes were studied using confocal laser scanning microscopy (CLSM), and the depth of lesions and demineralisation/remineralisation/infiltration percentage were calculated. Additionally, the macro elemental composition of the teeth was performed using atomic absorption spectroscopy (AAS). Two studies were performed: (i) demineralisation of enamel in 3% citric acid and infiltration treatment with infiltration resin (Icon, DMG), remineralisation with Fluor Protector (Ivoclar Vivadent) and artificial saliva pH 8; and (ii) enamel demineralisation in saliva at pH 3 and remineralisation at salivary pH 8. The results showed that, firstly, for the remineralisation of demineralised enamel samples, Fluor Protector (Ivoclar Vivadent) was very effective for medium demineralised lesions followed by saliva remineralisation. In cases of deep demineralisation lesions where fluoride could not penetrate, low viscosity resin (Icon, DMG, Hamburg) effectively infiltrated to stop the demineralisation process. Secondly, remineralisation in salivary conditions needed supplementary study over a longer period, to analyse the habits, diet and nutrition of patients in detail. Finally, demineralisation/remineralisation processes were found to influence the macro elemental composition of enamel demineralisation, with natural saliva proving to be less aggressive in terms of decreasing Ca and Mg content.

Spatial and Seasonal Drinking Water Quality Assessment in a Sub-Saharan Country (Guinea-Bissau)

The United Nations Sustainable Development Goal target 6.1 calls for universal and equitable access to safe and affordable drinking water. Worldwide, about 2.2 billion people live without access to safe water, and millions of people suffer from waterborne pathogens each year, representing the most pressing situation in developing countries. The aim of this study was to investigate the drinking water quality dynamics across an endemic cholera sub-Saharan country (Guinea-Bissau), and understand its implications for public health. Microbiological and physical–chemical quality parameters of 252 major water sources spread all over the country were seasonally surveyed. These comprised hand-dug shallow wells and boreholes, fitted with a bucket or a pump to retrieve water. The results showed that the majority of water sources available to the population were grossly polluted with faecal material (80%), being unsuitable for consumption, with significantly (p < 0.05) higher levels during the wet season. Hand-dug wells revealed the highest contamination levels. The chemical contamination was less relevant, although 83% of the water sources were acidic (pH < 6.5). This study highlights the potential health risk associated with the lack of potable drinking water, reinforcing the evidence for water monitoring, and the need to improve WASH (water, sanitation, and hygiene) infrastructure and water management in West African countries. In addition, the authors suggest easy-to-implement interventions that can have a dramatic impact in the water quality, assisting to reduce the associated waterborne diseases rise.

Quality Assessment of Three Types of Drinking Water Sources in Guinea-Bissau

The lack of access to safe drinking water causes important health problems, mainly in developing countries. In the West African country Guinea-Bissau, waterborne diseases are recognised by WHO as major infectious diseases. This study analysed the microbiological and physicochemical parameters of drinking water in the capital Bissau and its surroundings. Twenty-two sites belonging to different water sources (piped water, tubewells and shallow wells) were surveyed twice a day for three weeks, in both dry and wet seasons. Most of the microbiological parameters were out of the acceptable ranges in all types of water and both seasons and tended to worsen in the wet season. Moreover, in Bissau, the levels of faecal contamination in piped water increased from the holes to the consumer (tap/fountain). Several physicochemical variables showed values out of the internationally accepted ranges. Both well sources showed low-pH water (4.87–5.59), with high nitrite and iron levels in the wet season and high hexavalent chromium concentration in the dry season. The residual chlorine never reached the minimum recommended level in any of the water sources or seasons, suggesting a high risk of contamination. Results reveal a lack of quality in the three water sources analysed, coherent with the high number of diarrheal cases in the country. There is an urgent need to improve sanitarian conditions to reduce the disease burden caused by these waterborne illnesses.

Effects of Erosion Protocol Design on Erosion/Abrasion Study Outcome and on Active Agent (NaF and SnF2) Efficacy

There is no standard for testing anti-erosive/anti-abrasive agents, making the assessment and comparison of study results difficult. Factors which are varied in study designs are amongst others the erosive medium regarding concentration and pH or movement type of acid. The present study therefore investigated the impact of these factors on dimension of tissue loss and on efficacy of active agents used as anti-erosive/anti-abrasive therapeutics. In 8 experiments, consisting of 8 groups each (n = 20 each), resulting in a total of 64 groups, enamel specimens were demineralised (10 days, 6 × 2 min/day) using different acids (1, 0.5 and 0.3% citric acid at native pH 2.3, 2.5 and 2.8, respectively, and 0.3% citric acid adjusted to pH 3.6) with two different movement types (jerky or smooth). Specimens were immersed (2 × 2 min/day) in slurries of 1,450 ppm F- toothpaste (NaF), 1,450 ppm F- and 3,436 ppm Sn2+ toothpaste (NaF/SnF2), 970 ppm F- and 3,000 ppm Sn2+ gel (SnF2) or placebo, or were additionally brushed during immersion (15 s, 200 g). All groups were in between stored in a mineral salt solution. Tissue loss was determined profilometrically. Movement type, pH and concentration of acid had a substantial impact on study outcome. The combination of jerky movement and concentrated acid masked, to some extent, differences between erosive and erosive-abrasive tissue loss. The acid at low concentration (0.3%), independent of pH, was too mild to produce any tissue loss. The model with the best ability to demonstrate effects of abrasive impacts and active agents used the 1% acid concentration combined with smooth acid movements.

Effects of energy and sports drinks on tooth structures and restorative materials

Sports and energy drinks are consumed by more people than ever. Sports and energy drinks may enhance physical resistance, stimulate metabolism, prevent rehydration and replace electrolytes during high activity efforts. However, these drinks often have a low pH and are acidic, which can erode enamel and dentin, and increase dentine hypersensitivity. In addition to the adverse effects of sports and energy drinks on tooth structures, they often have the potential to damage restorative materials. These drinks often contain artificial colors which have potential to discolor resin composite materials and glass ionomers. The acidic nature of these drinks could also lead to a degradation, increase in wear, and roughening of the surface of the restorative materials. Many of the negative consequences of sport and energy drinks can be related to their over-consumption among children and teenagers. Patients should be advised to have a healthy diet, and consume soft and energy drinks in moderation, to avoid any negative dental or health consequences. The over-consumption of sports and energy drinks which are high in sugar and have the lowest pH are most likely to cause avoidable dental problems.

Erosive Effect of Different Soft Drinks on Enamel Surface in vitro: Application of Stylus Profilometry

OBJECTIVE

To assess the erosive potential of various soft drinks by measuring initial pH and titratable acidity (TA) and to evaluate enamel surface roughness using different exposure times.

MATERIALS AND METHODS

The initial pH of the soft drinks (group 1: Coca-Cola; group 2: orange juice; group 3: Cedevita; group 4: Guarana, and group 5: strawberry yoghurt) was measured using a pH meter, and TA was measured by titration with NaOH. Enamel samples (n = 96), cut from unerupted human third molars, were randomly assigned to 6 groups: experimental (groups 1-5) and control (filtered saliva). The samples were exposed to 50 ml of soft drinks for 15, 30 and 60 min, 3 times daily, during 10 days. Between immersions, the samples were kept in filtered saliva. Enamel surface roughness was measured by diamond stylus profilometer using the following roughness parameters: Ra, Rq, Rz, and Ry. Data were analyzed by one-way ANOVA, Tukey's post hoc and Student-Newman-Keuls post hoc tests.

RESULTS

The pH values of the soft drinks ranged from 2.52 (Guarana) to 4.21 (strawberry yoghurt). Orange juice had the highest TA, requiring 5.70 ml of NaOH to reach pH 7.0, whereas Coca-Cola required only 1.87 ml. Roughness parameters indicated that Coca-Cola had the strongest erosion potential during the 15 min of exposure, while Coca-Cola and orange juice were similar during 30- and 60-min exposures. There were no significant differences related to all exposure times between Guarana and Cedevita. Strawberry yoghurt did not erode the enamel surface regardless of the exposure time.

CONCLUSION

All of the tested soft drinks except yoghurt were erosive. Erosion of the enamel surfaces exposed to Coca-Cola, orange juice, Cedevita, and Guarana was directly proportional to the exposure time.

Smartphone based health accessory for colorimetric detection of biomarkers in sweat and saliva

The mobile health market is rapidly expanding and portable diagnostics tools offer an opportunity to decrease costs and increase the availability of healthcare. Here we present a smartphone based accessory and method for the rapid colorimetric detection of pH in sweat and saliva. Sweat pH can be correlated to sodium concentration and sweat rate in order to indicate to users the proper time to hydrate during physical exercise and avoid the risk of muscle cramps. Salivary pH below a critical threshold is correlated with enamel decalcification, an acidic breakdown of calcium in the teeth. We conduct a number of human trials with the device on a treadmill to demonstrate the ability to monitor changes in sweat pH due to exercise and electrolyte intake and predict optimal hydration. Additionally, we perform trials to measure salivary pH over time to monitor the effects of diet on oral health risks.