A method to measure clinical erosion: the effect of orange juice consumption on erosion of enamel

Effect of Nd:YAG laser and acidulated phosphate fluoride on bovine and human enamel submitted to erosion/abrasion or erosion only: an in vitro preliminary study

OBJECTIVE

The aim of the present in vitro study was to evaluate, using two different methodologies, the effectiveness of pulsed Nd:YAG laser irradiation associated with topical acidulated phosphate fluoride (APF) for preventing enamel erosion and structure loss under regimes of erosion and abrasion or erosion only.

BACKGROUND DATA

An increased incidence of noncarious lesions (erosion and abrasion) has been observed, consequently new preventative therapies have been proposed.

MATERIALS AND METHODS

Two different methodologies were performed. For the first, 100 bovine crowns were submitted to four different treatments (n = 25): no treatment (control), 4 min application of APF, Nd:YAG laser irradiation (1 W, 100 mJ, 10 Hz, 141.5 J/cm(2)), and Nd:YAG laser irradiation + 4 min of APF. After the specimens were exposed to citric acid (2% w/v; 30 min), they were submitted to 5000 brushing cycles. Specimen mass was measured before and after the treatments. For the second methodology, 20 human crowns were embedded in acrylic resin and cut surfaces were exposed and polished. The specimens were divided into four groups (n = 10): no treatment (control), APF for 4 min, Nd:YAG laser irradiation (1 W, 100 mJ, 10 Hz, 125 J/cm(2)), and Nd:YAG laser irradiation + APF. The samples were then immersed in citric acid (2% w/v; 90 min). Vickers hardness was obtained before and after the treatments.

RESULTS

The Nd:YAG laser irradiation + APF (bovine and human enamel) was more effective and yielded statistically significant results for surface microhardness and enamel wear.

CONCLUSION

Nd:YAG laser irradiation associated with APF reduced bovine enamel wear and human enamel softening when samples were submitted to a regime of erosion and abrasion or erosion only in vitro.

Viability of using enamel and dentin from bovine origin as a substitute for human counterparts in an intraoral erosion model

This study ascertained whether under dental erosion models that closely mimics the real-life situation enamel and root dentin from bovine origin would be reliable substitutes for human counterparts. Through a 2x2 crossover design, in a first trial, 14 volunteers wore a palatal device containing slabs of bovine and human enamel. Half of the participants ingested (4x daily, for 10 days) orange juice first, crossing over to mineral water, while the remainder received the reverse sequence. In a second trial, volunteers wore devices with slabs of bovine and human root dentin. Except for the duration of each intraoral phase, which lasted 2 rather 10 days, the experiment with root dentin run exactly as for enamel. Dental substrates were analyzed for surface microhardness. Two-way ANOVAs (α=0.05) indicated no difference between the microhardness values recorded for human and bovine enamel (p=0.1350), but bovine root dentin had lower microhardness compared to its human counterpart (p=0.0432). While bovine enamel can reliably substitute its human counterpart in in situ dental erosion models, bovine root dentin does not seem to be a viable alternative to the corresponding human tissue.

The in vitro erosive potential of a range of baby drinks

OBJECTIVE

The aim of this study was to assess the erosive potential of a range of commercially available baby drinks in the laboratory.

METHODS

The erosive potential of each product was assessed by measuring its initial pH, neutralizable acidity, and ability to erode primary and permanent enamel. These parameters were compared to those of an orange juice positive control.

RESULTS

The initial pH of the baby drinks ranged from 3.5 to 4.0 with their neutralizable acidity ranging from 5.76 to 16.02 mL of 0.1 m NaOH. The amount of primary enamel removed following 1-h immersion in the drinks ranged from 3.77 to 8.10 microns, while the amount of permanent enamel removed ranged from 1.09 to 4.86 microns. In comparison, the orange juice control (Tropicana smooth) had an initial pH of 3.86, a neutralizable acidity of 37.0 mL of 0.1 m NaOH, and removed 6.39 microns of primary enamel and 5.32 microns of permanent enamel.

CONCLUSION

All the baby drinks tested were found to be erosive; some of the products were as erosive as orange juice.

Protective effect on enamel demineralization of a CPP-ACP paste: an AFM in vitro study

OBJECTIVES

The aim of the present in vitro study was the evaluation of a CPP-ACP paste (Tooth Mousse) on preventing dental erosion produced by a soft drink (Coca Cola), using Atomic Force Microscopy (AFM).

METHODS

Thirty extracted human central incisors free of caries were selected and divided in a treatment and a control half. The treatment halves were divided in three groups-group 1: demineralization with soft drink (4 intervals of 2 min); group 2: demineralization with soft drink (4 intervals of 2 min) plus Tooth Mousse; group 3: intact enamel plus Tooth Mousse. In groups 2 and 3 Tooth Mousse was applied for 3 min at 0, 8, 24 and 36 h. The surface of each specimen was imaged by AFM and R(rms) values were registered.

RESULTS

Among treatment specimens of groups 1 and 2, a statistically significant difference (P<0.01) in R(rms) values was registered: treatment of the specimens with CPP-ACP paste had a protective effect on enamel demineralization. In group 3 no statistically significant difference was registered between exposed and not exposed halves of the specimens.

CONCLUSIONS

The use of a CPP-ACP paste had a protective effect on enamel demineralization in an in vitro model.

The enamel softening and loss during early erosion studied by AFM, SEM and nanoindentation

Enamel dissolution occurs when it contacts with acids produced by plaque bacteria, foods or drinks. There have been numerous and varied studies quantifying and characterizing the rate, extent and chemical aspects of enamel erosion; however, there is still hot debate about the amounts of enamel softening and loss. The objective of this study was to measure the enamel erosion process with high accuracy. Native third molars were partly eroded in citric acid (pH = 3.8) with some domains protected by a Ti coating layer. The surface morphology and structures before and after exposure to citric acid for different time periods were studied by AFM, SEM and nanoindentation, respectively. Based on this, the functions between the amounts of enamel softening, loss and erosion time were established for the first time. It was demonstrated that AFM, SEM and nanoindentation were suitable for measuring the early stages of enamel demineralization qualitatively and quantitatively.

Diet and dental erosion in young people in south-east Brazil

BACKGROUND

The regular consumption of acidic foods and drinks may be associated with dental erosion, and soft drink consumption appears to be increasing both in developed and developing countries. Dentists are aware that an acidic diet can contribute to the development of erosion; however, there may be confusion within the profession concerning the general health message of eating five portions of fruits and vegetables each day.

OBJECTIVE

The aim of this study was to investigate associations between dental erosion and the consumption of acidic foods and beverages in schoolchildren in south-east Brazil. The objective was to gather information, by means of a dietary questionnaire, on frequency of intake and patterns of consumption of acidic foods and drinks in a group of schoolchildren. The hypothesis was that the experience of dental erosion among the study sample was associated with the frequency and pattern of consumption of soft drinks, fruit juices, fruits, and yogurt.

METHODS

A cross-sectional study was conducted in Três Corações, south-east Brazil. A sample of 458 schoolchildren, mean age 13.8 (SD 0.39) years, completed the study. Information about potential dietary risk factors for dental erosion was collected through a questionnaire survey completed by the schoolchildren. For the dental examinations, the subjects were examined for dental erosion in a school room. Associations between dental erosion and the variables under study were investigated through processes of bivariate and multivariate analyses. The statistical significance level was set at 5%.

RESULTS

Analysis of the questionnaire surveys showed that the frequency of consumption of sugared carbonated drinks was the only variable independently associated with the erosive process, with subjects who had a daily consumption of such drinks having a greater likelihood of having erosion (P = 0.015, odds ratio 1.752, 95% confidence interval 1.116-2.750).

CONCLUSIONS

Of all tested factors in this sample of schoolchildren the consumption of sugared carbonated drinks is most associated with dental erosion.

The effect of dilution on the in vitro erosive potential of a range of dilutable fruit drinks

BACKGROUND

Only one previous study has investigated the effect which dilution has on the erosive potential of dilutable fruit drinks. Based solely on measurement of neutralizable acidity, the authors concluded that the erosive potential of diluting juices may be reduced substantially by the addition of water. This has not been verified in an in vitro enamel erosion model.

OBJECTIVE

The aim of this study was to examine the effect of dilution on the erosive potential of five dilutable fruit drinks.

METHODS

For each product, the erosive potential of three dilutions (1 : 3, 1 : 6 and 1 : 15) was assessed by measuring the initial pH and neutralizable acidity; in vitro enamel erosion was measured by profilometry following immersion for 1 h.

RESULTS

For the majority of products, increasing dilution from 1 : 3 to 1 : 15 produced a statistically significant rise in initial pH, though they remained markedly acidic. Increasing the dilution factor consistently produced a statistically significant decrease in neutralizable acidity. Increasing the dilution factor from 1 : 3 to 1 : 15 produced a statistically significant reduction in in vitro enamel erosion in only three of the five products tested.

CONCLUSIONS

Increasing the dilution factor of dilutable fruit drinks within a range likely to be acceptable to the consumer may not effectively reduce their erosive potential.

The measurement of enamel wear by four toothpastes

OBJECTIVES

To determine the enamel abrasivity of three whitening toothpastes and a silica toothpaste and to measure the brushing forces used.

METHODS

Polished human enamel blocks were indented with a Knoop diamond and attached to dentures of adult volunteers. The blocks were brushed ex vivo, twice per day with either a whitening toothpaste containing Perlite (White System), a commercial whitening toothpaste (A and B) or a silica toothpaste. After four and twelve-weeks, one block per subject was removed and the Knoop indent remeasured. From the changes in the indent length, the amount of enamel wear was calculated.

RESULTS

The mean enamel wear (sd) for White System, silica toothpaste, whitening toothpaste A and B after four-weeks was 0.14 (0.15), 0.09 (0.16), 0.14 (0.12) and 0.89 (0.93) and after twelve-weeks was 0.24 (0.21), 0.37 (0.73), 0.36 (0.52) and 1.04 (0.98) microm respectively. After four-weeks, the differences in enamel wear between whitening toothpaste B and all other toothpastes were of statistical significance (p < 0.003), but not after twelve-weeks. The mean ex vivo normal brushing force (sd) was 2.67 (1.33) N.

CONCLUSIONS

All three whitening toothpastes did not give significantly more enamel wear than a silica toothpaste after twelve-weeks in situ with ex vivo brushing.

Sour sweets: a new type of erosive challenge?

OBJECTIVE

To assess the erosive potential of a number of commercially available sour sweets in the laboratory.

METHODS

The erosive potential was assessed by measuring the pH, neutralisable acidity and ability to erode permanent and deciduous enamel. These parameters were compared to those of an orange juice positive control.

RESULTS

The pH of the sour sweets ranged from 2.30-3.14 with their neutralisable acidity ranging from 9.78-66.9 ml of 0.1M NaOH. The amount of permanent enamel removed following one hour immersion in the drinks ranged from 2.16-10.88 microm and from 1.02-18.34 microm for deciduous enamel. In comparison, the orange juice (Tropicana smooth) control had a pH of 3.86, a neutralisable acidity of 37.1 ml of 0.1M NaOH and removed 5.23 microm of permanent enamel and 6.27 microm of deciduous enamel.

CONCLUSION

All the sour sweets tested were found to be erosive, some more so than orange juice. This information will be of use to clinicians when counseling younger patients with tooth surface loss.

Evaluation of a profilometrical method for monitoring erosive tooth wear

The in vivo monitoring of erosive wear is difficult because lesions mostly progress relatively slowly and reliable reference points are difficult to obtain. To date, only a few methods for clinical monitoring of erosive loss have been described, which either require extensive equipment or do not provide sufficient sensitivity. The aim of the present study was to evaluate, using study models (epoxy resin material), a procedure that permits the reliable and accurate monitoring of erosive substance loss within acceptable observation periods. The method is the profilometric measurement of erosive tissue loss using acid-resistant markers, which represent both a reference area and a structure for the defined retracing of a given erosive lesion surface. The study model magnified values slightly (2.8%; not significant), the precision was < 4 microm, and the repeatability was good (95% limits of repeatability ranging from -4.7 to 5.2 microm). The estimated detection threshold for erosive loss is 15 microm, which appears to be adequate for monitoring. The method is indicated for special dental care in cases of severe dental erosion (e.g. eating disorders) and for clinical studies.

The protective effects of toothpaste against erosion by orange juice: Studies in situ and in vitro

OBJECTIVES

There has been a monumental increase in the consumption of soft drinks, fruit juices and sport drinks in the UK, the US, and many other countries. Previous investigations have demonstrated the erosive nature of these acidic soft drinks. The aim of this investigation was to determine the protective effects of an experimental fluoride-based toothpaste, containing sodium hexametaphosphate, against an erosive challenge on tooth enamel.

METHODS

The erosion of enamel by orange juice compared the experimental toothpaste with a benchmark sodium fluoride paste and negative control, water, in a 15-day in situ model; and the same in an in vitro enamel erosion model. Flat, polished human enamel samples with a surface profile of +/-0.1mum, were exposed to the three regimens in the single blind, crossover clinical study mimicked in vitro. Depths of the resulting eroded areas were measured using a profilometer.

RESULTS

There was significantly more erosive damage on the specimens exposed to the benchmark paste and water compared to the test paste in both the in situ and in vitro studies.

CONCLUSIONS

The data provide further support for tooth brushing before meals. Results of this study further suggest the sodium hexametaphosphate containing paste could be used to provide significant erosion protection in susceptible individuals over that provided by conventional fluoride products.

A clinical study in situ to assess the effect of a food approved polymer on the erosion potential of drinks

OBJECTIVES

The consumption of acidic soft drinks continues to rise as do concerns regarding effects of frequent intake. The aim of the study was to determine the effect of acidic soft drinks containing food approved polymers, on dental enamel.

METHODS

The study design was a single blind, randomised, five-treatment crossover clinical trial involving 15 healthy dentate subjects. Subjects wore an upper removable acrylic appliance retaining two enamel specimens and consumed 250ml of beverage four times/day for 10 days. The following beverages were tested: (1) unmodified acidic soft drink, (2) experimental acidic soft drink with 0.02% polyphosphate, (3) experimental acidic soft drink with 0.02% polyphosphate and 0.01% calcium, (4) experimental acidic soft drink with 0.02% polyphosphate and 0.03% xanthan gum, and (5) mineral water. Tissue loss was measured at days 5 and 10 of each study leg using a profilometer.

RESULTS

The order of erosion from most to least at day 10 was unmodified acidic soft drink>experimental acidic soft drink with polyphosphate>experimental acidic soft drink with polyphosphate+gum>experimental acidic soft drink with polyphosphate+calcium>mineral water. At day 10 the unmodified acidic soft drink was significantly (p=0.001) more erosive than all other drinks.

CONCLUSIONS

Unmodified acidic soft drink with the addition of polyphosphate alone or combined with calcium or xanthan gum are all effective at reducing erosion of enamel compared with the unmodified soft acidic drink.

An in vitro investigation of the effect of some analgesics on human enamel

The sale of over-the-counter pain relief medication has increased dramatically in recent years, and typically amounts to several hundred thousands of pounds per year in the UK. Many soluble analgesic preparations contain citric acid, and it has been suggested that these formulations may cause dental erosion. The aim of this study was to investigate the effect of some over-the-counter analgesics on tooth surface loss from human enamel. Six commonly available analgesics were chosen for this study and the effect of immersing unerupted human enamel was examined using non-contact optical profilometry. Two of the six analgesics investigated caused no detectable erosion (Boots soluble aspirin and Anadin Extra). Three caused statistically significant enamel erosion, but this was very slight and is thought to be clinically insignificant (Alka Seltzer, Panadol and Solpadeine). Only one analgesic caused possible potentially clinical significant enamel erosion. Further studies are needed to determine whether Aspro causes clinically significant enamel erosion.

Pronamel and tooth mousse: An initial assessment of erosion prevention in vitro

OBJECTIVES

The aim of this study was to examine whether a single topical application of proenamel or tooth mousse would prevent enamel erosion

METHODS

Enamel samples were treated with either proenamel or tooth mousse applied for 15 min. The control group was placed in distilled water for 15 min. All specimens were then exposed to an erosive challenge of 0.2% citric acid for 1h. Enamel loss was determined using surfometry.

RESULTS

The mean amount of enamel removed in the control group was 5.02 microm (S.D. 1.16). The mean enamel loss in the proenamel group was 2.60 microm (S.D. 0.90) and the mean enamel loss in the tooth mousse group was 3.28 microm (S.D. 1.22). The results for the proenamel group were statistically significantly different from the control group at the p<0.01 level and the results for the tooth mousse group were statistically significantly different from the control group at the p<0.05 level.

CONCLUSIONS

Tooth mousse and proenamel may offer a degree of protection from erosion of permanent enamel.

Exposure Time of Enamel and Dentine to Saliva for Protection against Erosion: A Study in vitro

Previous research, mainly on enamel, supports a protective role for salivary pellicle against erosion. Pretreatments have tended to be lengthy (24 h or more) and of questionable relevance to the regular intake of acidic food and drink by many individuals. The aim of this study in vitro was to determine the protective effect of salivary pellicle formed on enamel and dentine over time periods up to 4 h. Flattened, polished human enamel and dentine specimens were pretreated with unstimulated human saliva from a single donor for 2 min, 30 min (enamel only), 1, 2, or 4 h. Controls were exposed to water for the same times. Specimens were then exposed to 0.3% citric acid, pH 3.2 for 10 min with stirring. This cycle was carried out 12 times. Tissue loss was measured by profilometry after 3, 6, 9 and 12 cycles. For enamel, statistically significant protection was found at >or=1 h. For dentine, significant protection was achieved at 2 min. Salivary pellicle offered proportionately greater protection to enamel than dentine. Cautiously extrapolating these in vitro data suggests that pellicle should offer erosion protection to individuals who imbibe acidic drinks at frequencies of 1 h or less.

Wear of dentine in vitro by toothpaste abrasives and detergents alone and combined

AIM

To measure in vitro the abrasion of dentine by toothpaste detergents and abrasives alone and combined.

MATERIALS AND METHODS

Detergents used were tego betain, sodium lauryl sulphate (SLS), adinol and pluronic diluted to 1% w/v. Abrasives were three artificial silicas, tixosil 73 and 123 and Zeodent 113, and calcium carbonate used at 2.5% w/v. Flat human dentine specimens were brushed with aqueous detergent solutions or abrasive slurries, detergent abrasive slurries and water for 20,000 brush strokes. Dentine loss was measured by non-contacting profilometry at 10,000 and 20,000 strokes. Silica particle size distribution was measured by laser deflection.

RESULTS

Loss of dentine occurred with all detergents, abrasives and detergent abrasion combinations, but was not linear with number of brush strokes. Water appeared to remove the smear layer only, but all detergents exceeded the predicted smear layer thickness. The silica abrasives differed in abrasion properties despite similar particle size distribution. Different detergents modulated the abrasives actions in mainly positive or mainly negative directions.

CONCLUSIONS

Detergents appear able to attack the dentine surface to produce wear. Abrasives vary considerably in wear produced under similar conditions. Detergents modulate the effect of abrasives in a way that may reflect the rheological properties of the mixture.

The relationship between enamel softening and erosion caused by soft drinks at a range of temperatures

OBJECTIVES

Investigations of the erosive potential of soft drinks are usually performed at room or body temperature, but drinks are more frequently served chilled, with ice, or hot. Since the rate of chemical reactions usually increases with temperature, it is predicted that erosion is more severe at high temperatures and reduced at low temperatures. The aim of this study was to investigate the correlation between enamel softening, enamel erosion, and temperature.

METHODS

Atomic force microscopy nanoindentation and non-contact optical profilometry were used to assess changes in enamel nanomechanical properties after 5 min and erosive material loss after 30 min exposure to two different non-carbonated soft drinks at 4, 25, 50 and 75 degrees C.

RESULTS

For one drink (Robinson's Original Juice Drink), there was a statistically significant difference between nanomechanical properties and erosion depth at all temperatures, with softening and erosion increasing with temperature. For another drink (Ribena ToothKind Juice Drink), there was a slight softening and virtually no material loss, and temperature had no statistically significant impact on erosion. There was a good linear correlation (R2 = 0.94) between nanomechanical properties and material loss.

CONCLUSIONS

The difference between the drinks can be explained by their composition. For the erosive drink, material loss increased, and nanohardness decreased, approximately linearly with temperature. The correlation between softening and erosion demonstrated that nanomechanical properties after very short erosion times can be considered a good predictor of bulk material loss after considerably longer erosion times.

Abrasion of human enamel and dentine caused by toothpastes of differing abrasivity determined using an in situ wear model

OBJECTIVES

To determine the rates of enamel and dentine wear in situ during tooth brushing with a range of five toothpastes of differing RDA and REA values.

METHODS

Enamel/dentine inserts were placed in the buccal aspects of full upper dentures of human volunteers. Enamel wear was determined by change in Knoop indent length and dentine wear was determined from the enamel-dentine step height, measured using optical profilometry.

RESULTS

Significant differences between the test products were found for both enamel and dentine (p < 0.05). However for the conventional toothpastes the rate of wear was similar and differences between the products were not generally statistically significant for either enamel or dentine, despite the fact that their RDA values differed by more than a factor of two. The rate of wear was found to decrease throughout the duration of the study.

CONCLUSIONS

The study demonstrated that the methodology used is capable of assessing enamel and dentine wear in situ within a relatively short period of time. The data suggest that whilst in vitro tests have value in understanding differences in abrasivity between products, they cannot be used to predict in vivo effects.

Comparison of Calcium/Phosphorus Analysis, Longitudinal Microradiography and Profilometry for the Quantitative Assessment of Erosive Demineralisation

The study is a comparison of methods for the quantitative measurement of erosive mineral loss including longitudinal microradiography (LMR), profilometry (PM), and analysis of calcium (CA) and phosphorus (PA) in the erosion solution. Polished human enamel samples were taped, covered with nail varnish and the edges of the resulting enamel window marked with drilled holes as a reference. All samples were subjected to baseline LMR. Sixty samples each were eroded with citric acid (0.05 M; pH 2.3; 10 ml per sample) for 30, 60, 90, or 120 min. Erosive loss of each sample was estimated by the four methods. All methods revealed a linear erosive loss over time and showed good linear correlation. Values calculated from PM and LMR were both approximately 20% lower than those from CA and PA. After 30 min erosion, LMR showed no significant correlation with the other three methods. With LMR, erosive loss below 20 microm should be interpreted with care.

A study in vitro of the combined effects of soft drinks and tooth brushing with fluoride toothpaste on the wear of dentine

The aim of this study was to measure loss of dentine produced by soft drinks alone and combined with tooth brushing with and without toothpastes. Groups of flat human dentine specimens were exposed for 10 min and then 30 min to orange juice (OJ), carbonated cola (CC) or modified blackcurrant (MB) drinks alone or after the exposures brushed with a fluoride toothpaste for 10 s. Further groups were exposed to OJ as before but brushed with water or non-fluoride toothpaste or placed in slurries of fluoride paste. Five cycles of each regimen were carried out. Tissue loss was determined by profilometry. Water immersion/brushing and brushing controls were included. OJ and CC produced similar erosion and significantly more than MB. Compared with drinks alone, dentine loss was reduced by fluoride toothpaste brushing but increased by water and non-fluoride toothpaste brushing. Fluoride toothpaste slurry had no significant effect on soft drink erosion. Very little abrasion with brushing alone was recorded over the time frame of these experiments. It is concluded that fluoride toothpaste could provide protection, albeit small, against erosion. The data again support the concept of brushing before meals.

Dental erosion due to wine consumption

BACKGROUND

Dental erosions can result from numerous causes, but extrinsic dietary factors are the most common. Because of wine's acidity, it may have a deleterious effect on teeth. Its use must be considered during an evaluation of erosive dental changes.

CASE DESCRIPTION

The author examined a 56-year-old woman because her referring dentist had noted extensive erosive loss of tooth structure, mainly enamel. The author eliminated the usual causes of dental erosion. It was only after a detailed history was obtained and dietary investigation was undertaken that the author determined that the amount, manner and timing of the patient's wine drinking was the cause of the problem.

CLINICAL IMPLICATIONS

Dentists should be aware that wine could be a cause of dental erosion. Early recognition negates progressive dental damage with its need for extensive dental restoration. Furthermore, because patients with wine-incited dental erosions consume large volumes of wine with its significant alcohol content, medical referral by the dentist for a liver assessment is indicated.

Erosive Effect of a New Sports Drink on Dental Enamel during Exercise

PURPOSE

To compare the potential erosive effect of a prototype carbohydrate-electrolyte drink (PCE) with a neutral control (water) and a commercially available carbohydrate-electrolyte drink (CCE) during exercise.

METHODS

: Nineteen healthy adults (male, N = 16; female, N = 3) took part in this single blind, three-way crossover study. Subjects were given each of the three drinks according to a randomization schedule, approximately balanced for first-order carryover effects. At the beginning of each of the three study periods, the volunteers were fitted with an intraoral appliance containing two human enamel blocks. During each study period, volunteers exercised for 75 min.d(-1) (5 repetitions of 15 min of exercise, with 5-min rests between exercise repetitions), 5 d.wk(-1) for 3 wk. Each day, drink aliquots of 200 mL were consumed during a 5-min period before exercise and after every 15-min bout of exercise, followed by a final 400-mL aliquot ingested over a 10-min period: a total of 1400 mL per study day. Dental erosion was measured as tissue loss from the enamel blocks by profilometry at the end of each study period.

RESULTS

Water, PCE, and CCE produced 0.138 microm (SD 0.090 microm), 0.138 microm (SD 0.038 microm), and 4.238 microm (SD 3.872 microm) of enamel loss, respectively. A Wilcoxon t statistic showed a significant statistical difference between the PCE and CCE drinks (P < 0.001), whereas no significant difference could be detected between the PCE drink and water (P = 0.740).

CONCLUSION

The PCE solution showed minimal erosion compared with the commercially available drink, and was statistically indistinguishable from water under the conditions of this study. Use of CE solutions formulated to minimize erosion during exercise may provide significant dental benefits.

A methodology for testing the erosive potential of sports drinks

OBJECTIVES

The aim of the study was to develop and test a methodology in situ, which simulated the consumption of sports drinks. A secondary aim was to assess the acceptability of the method to sedentary participants.

METHODS

To select the sports drink for the study in situ, five commercially available sports drinks were examined for erosive potential in vitro. The study in situ was a single centre, 2-period, 2-treatment crossover study to compare the erosive effect of a commercially available sports drink (Test), with that of mineral water (Control), over 10 day periods on 10 healthy volunteers. Subjects wore upper removable appliances containing two human enamel specimens from 9 a.m. to 5 p.m. The regimen of intake of the drinks was 350 ml in 10, 5-min rest, 650 ml in 25, 5-min rest, 500 ml in 10 and 5-min rest. Measurements of enamel loss were made on samples after 5 and 10 days by profilometry.

RESULTS

The in situ study showed a statistically significant difference in erosive potential between the test and control beverages. No specimen exposed to the control beverage displayed appreciable erosion. Erosion occurred with the test drink, but to a variable degree between subjects. The subjects unanimously found the drinking regimen unpleasant.

CONCLUSIONS

The sports drink caused significantly more erosion in situ than water and as seen in other studies, there was marked variation in susceptibility to erosion between subjects. The new drinking regimen was designed to simulate pre, during and post-exercise intake. Although all the sedentary subjects participating in this study reported that they found the volume of fluids consumed over a short period of time excessive it is unlikely that this would prove problematic in the exercise environment.

A comparison of enamel erosion by a new sports drink compared to two proprietary products: a controlled, crossover study in situ

OBJECTIVE

The aim of the study was to measure the erosive potential of a prototype sports drink on enamel in a model in situ.

METHODS

The study was a single centre, single blind, randomised crossover design balanced for residual effects involving 18 subjects. The drinks were the prototype formulation containing calcium and maltodextrin (test), two sports drink products containing sugars (drink with calcium and positive control) and water (negative control). During each 15-day study period, subjects wore a palatal removable appliance carrying two flat human enamel specimens. Drinks were imbibed as 250 ml volumes over 10 min 4 times per day. Loss of enamel was measured on days 5, 10 and 15 using a contacting profilometer.

RESULTS

Very little erosion occurred with the test, drink with calcium and negative control drinks and differences between the test and negative control only reached significance at day 15. The positive control produced progressive erosion over time and significantly more than the test or negative control at all time points.

CONCLUSION

The technology of adding calcium with appropriate pH adjustment, which has been applied previously to soft and carbonated drinks to markedly reduce erosive potential, can be applied to sports drinks to the same end. Significant variation in the carbohydrate composition does not influence this outcome.

The laboratory assessment of enamel erosion: a review

OBJECTIVES

To review the various methods and techniques available to assess enamel erosion in vitro.

DATA

Peer reviewed scientific articles.

SOURCES

Medline and Web of Science searches and manual searching.

STUDY SELECTION

Laboratory based assessments only included.

CONCLUSIONS

A number of macroscopic and microscopic techniques have been used to assess enamel erosion in vitro and in situ. This review examines techniques which are either well established or comparatively novel techniques that are being explored for their potential.

A Study in vitro of the Abrasive Effect of the Tongue on Enamel and Dentine Softened by Acid Erosion

The palatal aspect of upper anterior teeth appears to be one site of predilection for erosion. This raises the question of whether abrasion of softened enamel and dentine by the tongue has a role in this process. The aim of this study in vitro was to determine whether enamel and dentine specimens licked by the tongue after exposure to acid lost more tissue than when exposed to acid alone. Flat enamel and dentine specimens were prepared from human third molars and taped to expose a window of tissue. Three groups of specimens were exposed to citric acid for 10 min followed by 60 s tongue licking, ultrasonication or immersion in water. Two further groups of enamel specimens were placed in a low erosive drink for 10 min with or without licking. At the end of 5, 10 and 15 treatment cycles tissue loss was measured by profilometry. Enamel loss was significantly greater with licking and ultrasonication compared to water immersion. Dentine loss was greater with licking and ultrasonication compared to water immersion, but differences only reached significance for ultrasonication. The low erosive drink produced one third of the citric acid erosion and licking had no effect. The results suggest that the tongue could exert an abrasive effect on dental tissues softened by erosion, thereby increasing the overall loss of tooth substance.

A safety study in vitro for the effects of an in-office bleaching system on the integrity of enamel and dentine

OBJECTIVE

The aim of this study was to investigate safety concerns with bleaching procedures by studying the effects of a high concentration hydrogen peroxide (HP) in-surgery bleaching product on enamel and dentine.

METHOD

Flat enamel and dentine samples embedded in epoxy resin were prepared from human third molar teeth. Erosion of enamel: groups of enamel samples were treated with 35% HP then citric acid (CA) or brushing with toothpaste or CA alone and water alone. Enamel Loss was measured using a profilometer. Abrasion/erosion of dentine: groups of dentine specimens were treated as follows: Group 1--brushed with water for 30 min. Group 2--brushed with 35% HP for 30 min. Group 3--power bleached for 30 min and then Group 4--brushed with toothpaste for 1 minute. Group 5--water soaked for 30 min followed by brushing with toothpaste for 1 min. Group 6--orange juice soaked for 30 min followed by brushing with toothpaste for 1 min. Treatment effects were measured using a profilometer. Hardness tests: enamel and dentine specimens were hardness tested using a Wallace indenter prior to and post bleaching. Scanning Electron Microscopy: enamel and dentine specimens were taped and the exposed tissue treated with 35% HP and then studied under scanning electronmicroscopy (SEM).

RESULTS

Enamel erosion: bleaching enamel samples had no measurable effect on enamel. Pre-bleaching had no significant effect on subsequent CA erosion or brushing. Abrasion/erosion of dentine: no significant differences were found between treatments 1-5 with little change from baseline detected. Orange juice (Group 6) produced considerable and significantly more erosion than other treatments. Hardness tests: there were no significant changes in hardness values for enamel and dentine. SEM: there was no evidence of any topographical changes to either enamel or dentine.

CONCLUSION

Using one of the highest concentrations of HP for tooth bleaching procedures and maximum likely peroxide exposure, there was no evidence of deleterious effects on enamel or dentine. It must be assumed that studies which reported adverse effects on enamel and or dentine of bleaches reflect not the bleach itself but the pH of the formulation used.

An in situ model to study the toothpaste abrasion of enamel

OBJECTIVES

In order to understand the clinical relevance of dentifrice abrasivity on the dentition in vivo, an in situ enamel wear model has been developed.

MATERIALS AND METHODS

Polished human enamel blocks were indented with a Knoop diamond, attached to dentures and worn by adult volunteers for 24 h per day. The blocks were brushed for 30 s, twice per day with dentifrices of known relative dentine abrasivity (RDA) and relative enamel abrasivity (REA). The dentifrices used were either dentifrice A (RDA=85, REA=3.4), dentifrice B (RDA=189, REA=2.0) or dentifrice C (RDA=132, REA=42.7). After 28 days, the blocks were removed and the geometry of each Knoop indent was remeasured. From the baseline and post-treatment values of indent length, the amount of enamel wear was calculated from the change in the indent depth.

RESULTS

The median values for enamel wear of dentifrices A, B and C were -0.02, 0.01 and -0.48 microm, respectively. The differences between dentifrice C and dentifrices A and B were of statistical significance.

CONCLUSION

This study has demonstrated the usefulness of an in situ technique for investigating the relationship between the abrasivity of a dentifrice in vitro and the wear of enamel in situ.

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.

The protective effect of fluoride treatments against enamel erosion in vitro

Fluoride is known to reduce enamel solubility during the caries process. The aim of this investigation was to determine whether fluoride preparations affect erosion attributed to citric acid and citric acid-based soft drinks. Flat enamel specimens embedded in epoxy resin were prepared from caries free, human third molar teeth extracted from patients aged 18-35 years. Specimens were polished to have a profile within a tolerance of +/-0.3 microm measured on a profilometer. Specimens were taped to leave a 2 mm window of exposed enamel. Groups of specimens were exposed to citric acid and soft drinks with and without the addition of sodium fluoride or exposed to the same solutions after pre-treatment with fluoride products. Enamel loss was measured by profilometer after 10, 20 and 30 min of acid exposure. The different acidic solutions varied significantly in the amount of erosion produced both with and without the addition of fluoride. In addition, the different fluoride products differed significantly in the protective effect afforded. Both fluoride application methods reduced in mean terms, enamel erosion at all time points and by all acidic solutions. The majority of differences were <25% and as the study was powered to show differences as significant at or above this level few reached statistical significance. Fluoride applied to enamel either in acidic solutions or as a pre-treatment, reduces enamel erosion; however, the actual clinical benefit appears low. More studies are required, including investigations in situ.

Influence of liquid temperature and flow rate on enamel erosion and surface softening

Enamel erosion and softening are based on chemical processes which could be influenced by many factors including temperature and acid flow rate. Knowledge of the influence of these variables could have relevance to research experiments and clinical outcomes. Both parameters were investigated using an ultrasonication and profilometry method to assess erosion depth and surface softening of enamel. The influence of temperature was studied by eroding polished human enamel samples at 4, 20, 35 or 50 degrees C for 2 h. Secondly, different liquid flow conditions were established by varying acid agitation. Additionally, a slow laminar flow and a jet of citric acid, to simulate drinking through a straw, were applied to specimens. Erosion depth increased significantly with acid temperature from 11.0 microm at 4 degrees C to 35.8 microm at 50 degrees C. Surface softening increased much more slowly and plateaued at 2.9 microm to 3.5 microm after 35 degrees C. A strong dependence of erosion on liquid flow was revealed. In unstirred conditions only 8.6 microm erosion occurred, which increased to 22.2 microm with slow stirring and 40.9 microm with fast stirring. Surface softening did not increase correspondingly with its largest extent at slow stirring at 3.4 microm.The implication of these data are: first, the conditions for erosion experiments in vitro or in situ need to be specified for reliable comparisons between studies. Secondly, erosion of teeth by soft drinks are likely to be influenced both by the temperature of the drink and individual drinking habits.

Investigation of erosion and abrasion on enamel and dentine: a model in situ using toothpastes of different abrasivity

BACKGROUND

Studies in vitro suggest that abrasion and erosion may act synergistically to produce wear of enamel and dentine. Methods in situ are recently available to study separately erosion and abrasion of dental tissues. The aim of this study was to combine two in situ protocols to study the interplay between erosion and abrasion of enamel and dentine.

METHOD

The study was a single-blind, randomised, five-treatment cross-over design involving 15 healthy volunteers. During each 10-day study period, subjects wore from 0900 to 1700 h an upper removable acrylic appliance holding one polished enamel and one polished dentine specimen. The specimen treatment regimens were: 1. Drinking water and brushing with toothpaste A. 2. Drinking water and brushing with toothpaste B. 3. Drinking orange juice. 4. Drinking orange juice and brushing with toothpaste A. 5. Drinking orange juice and brushing with toothpaste B. Drinking and brushing times were around 0900, 1100, 1300 and 1500 h. Drinks were consumed as 250 ml over 10 min and brushing ex vivo for 1 min to each specimen. Measurement of tissue loss was made on days 5 and 10 of each period using a profilometer.

RESULTS

All treatments produced increasing tissue loss over time, which was considerably greater for dentine than enamel. For enamel, the data at days 5 and 10 showed a significant effect for erosion (i.e. orange juice was significantly more erosive than water), but no significant effect for abrasion (i.e. no significant difference between the two toothpaste treatments). The combined orange juice and toothpaste effects were directional for synergy but did not reach significance. For dentine at day 10, many specimens exceeded the 50 microm set limit of the profilometer and only day 5 data were considered. There were significant effects for erosion (orange juice produced significantly more erosion than water) and for abrasion (paste A was significantly more abrasive to dentine than paste B). The synergy effect could not be examined for dentine due to the truncation effect as the set limit of the profilometer was exceeded.

CONCLUSIONS

Erosion increases the susceptibility of enamel to toothpaste abrasion. Dentine is considerably more susceptible than enamel to erosion and abrasion alone or combined. Dentine loss appears to correlate with toothpaste abrasivity (RDA value).

Development of low erosive carbonated fruit drinks 2. Evaluation of an experimental carbonated blackcurrant drink compared to a conventional carbonated drink

OBJECTIVE

Previous studies demonstrated that a non-carbonated blackcurrant juice drink with added calcium produced little erosion of enamel in vitro and in situ by comparison with other low pH fruit drinks. The aim of this study is to evaluate the erosive effects in situ of an experimental formulation carbonated drink with added calcium, compared to a conventional carbonated drink over a 20 day period using a similar design as in previous studies.

METHOD

The study was a single centre, single blind, randomised placebo controlled three cell crossover design involving 15 volunteers. The test drinks were an experimental carbonated ready-to-drink (RTD) blackcurrant drink, a conventional carbonated RTD orange drink and water. Two enamel samples were retained in situ, in the midline of the hard palate on an upper removable acrylic appliance. Drinks were 250 ml volumes consumed four times per day during 20 working days. Measurements of enamel loss were made on enamel samples after days 2, 5, 10, 15 and 20 by profilometry.

RESULTS

The experimental carbonated blackcurrant drink caused significantly less enamel loss than the conventional carbonated orange drink at all time points measured, but was not significantly different from water at days 2, 5 and 20.

CONCLUSIONS

This study has shown that it is possible to modify carbonated soft drinks in a manner similarly shown with non-carbonated soft drinks, to minimise dental erosion.

The erosive potential of some herbal teas

OBJECTIVES

Many epidemiological studies show a high prevalence of tooth wear, even in young patients. One factor that may be contributing to this problem is the consumption of herbal teas that are often considered to be 'healthy' alternatives to other beverages. The aim of this study was to screen a number of these products for their potential to cause erosion.

METHODS

The erosive potential of a variety of herbal teas was assessed in the laboratory by measuring their pH, neutralisable acidity and their ability to erode enamel and these were compared to a positive control, orange juice.

RESULTS

The pH of the herbal teas ranged from 3.1 to 7.1 and the neutralisable acidity ranged from 3.5 to 60.3 ml of 0.1M NaOH. The amount of enamel removed following 1h immersion in the herbal teas ranged from 0.00 to 9.6 microm. In comparison, the orange juice control had a pH of 3.7 a neutralisable acidity of 21.4 ml and removed 3.3 microm of enamel.

CONCLUSIONS

Many of the herbal teas tested were found to be more erosive than orange juice. This information will be of use to clinicians when counseling patients with tooth surface loss.

Development of low erosive carbonated fruit drinks. 1. Evaluation of two experimental orange drinks in vitro and in situ

OBJECTIVES

To determine the in vitro erosive potential and in situ erosive effect of two new formulation low calorie carbonated orange drinks with that of two conventional diet products and water.

METHODS

In the in vitro study, six specimens of deciduous and permanent enamel were randomly allocated to each of the five products and a '4h' protocol employed. In the in situ study, 15 healthy volunteers participated in a single centre, single blind, 5-phase crossover study, conducted according to Good Clinical Practice, and employing a validated model.

RESULTS

The in vitro erosive potential of the experimental formulations was less than that of the comparators at all time points. Conversely, the observed erosive potential of both experimental formulations was greater than that of the control. Consistent statistically significant differences were found in relation to permanent enamel only. Unfortunately, the in situ study did not produce results entirely consistent with those of the in vitro study. Notably, a generally progressive loss of enamel was observed in specimens exposed to the control.

CONCLUSIONS

The data from the in vitro study show the experimental formulations to have low comparative erosivity. However, the methodologies in vitro and in situ somewhat unusually do not correlate in ranking the erosivity of drinks. The results of this study should therefore be viewed with caution, further research being clearly warranted.

A comparison of the erosive susceptibility of cuspal and cervical enamel using an ultrasonic technique

The aim of this study was to compare the erosive susceptibility of cuspal and cervical enamel from human premolar and molar teeth. Small blocks of cervical and cuspal enamel were immersed in either orange juice or Coca-Cola at 37 degrees C and the surface enamel loss was measured by surfometry at 1, 2, 3 and 4 h. Additionally, once-hourly enamel loss was measured, specimens were placed in an ultrasonic bath containing water and ultrasonicated for 5 s to determine the degree of surface demineralization. A further set of enamel specimens were prepared that had 100 microm of the enamel surface removed. This was done to remove the hypermineralized surface enamel layer. Surface enamel loss in orange juice at 4 h, following ultrasonication, ranged from 13.2 to 16.9 microm. The surface enamel loss in Coca-Cola at 4 h, following ultrasonication, ranged from 21.7 to 27.5 microm. Subsurface enamel loss in orange juice at 4 h, following ultrasonication, ranged from 10.7 to 16.1 microm. The subsurface enamel loss in Coca-Cola for 4 h, following ultrasonication, ranged from 36.8 to 37.2 microm. Overall, little difference was found in the erosive susceptibility of cervical and cuspal enamel to the effects of orange juice or Coca-Cola.

Development of a method in situ to study toothpaste abrasion of dentine. Comparison of 2 products

BACKGROUND/AIMS

The abrasivity of toothpastes is usually determined using in vitro methods; as such, the clinical significance of the findings is uncertain. The aim of the present study was to develop and evaluate a method in situ to study abrasion of dentine by two toothpastes of different Relative Dentine Abrasivity (RDA).

METHOD

The study was a single blind, randomised, 2 way cross over design involving 10 healthy dentate volunteers. Subjects wore an maxillary removable acrylic appliance containing two flat human dentine specimens, taped to expose a window of tissue, from 9 am to 4 pm during the two 10 working day study periods. No food or drink was consumed when the appliance was in place. On five occasions each day, the appliances were removed and the dentine windows brushed ex vivo with the allocated paste for 60 s each. Dentine abrasion at days 5 and 10 was measured using a profilometer.

RESULTS

Both toothpastes produced measurable abrasion in all subjects and the depth increased in most subjects between 5 and 10 days. There was significant subject and specimen variation both within and between toothpastes. There was significantly increased abrasion by the toothpaste with the higher RDA value and in mean terms the ratio of abrasion between the two pastes was similar to the ratio of the RDA values.

CONCLUSION

The method in situ, already used to study dental hard tissue erosion, appears ideally suitable to study dental abrasion alone and the interaction between aetiological factors involved in tooth wear.