Thomas Jaeggi

The Role of Diet in the Aetiology of Dental Erosion

Acids of intrinsic and extrinsic origin are thought to be the main etiologic factors for dental erosion. There is evidence that acidic foodstuffs and beverages play a role in the development of erosion. However, the pH of a dietary substance alone is not predictive of its potential to cause erosion as other factors modify the erosive process. These factors are chemical (pKa values, adhesion and chelating properties, calcium, phosphate and fluoride content), behavioural (eating and drinking habits, life style, excessive consumption of acids) and biological (flow rate, buffering capacity, composition of saliva, pellicle formation, tooth composition, dental and soft tissue anatomy). The interplay between erosion and abrasion (specially oral hygiene practices) may be the main driver leading to the clinical manifestation of this disorder. Recommendations for patients at risk for dental erosion such as reducing acid exposure by reducing the frequency and contact of acids will be discussed.

Prevalence, incidence and distribution of erosion.

There is some evidence that the presence of erosion is growing steadily. Because of different scoring systems, samples and examiners, it is difficult to compare and judge the outcome of the studies. Preschool children aged between 2 and 5 years showed erosion on deciduous teeth in 6-50% of the subjects. Young schoolchildren (aged 5-9) already had erosive lesions on permanent teeth in 14% of the cases. In the adolescent group (aged between 9 and 17) 11-100% of the young people examined showed signs of erosion. Incidence data (= increase of subjects with erosion) evaluated in three of these studies were 12% over 2 years, 18% over 5 years and 27% over 1.5 years. In adults (aged between 18 and 88), prevalence data ranged between 4 and 82%. Incidence data are scarce; only one study was found and this showed an incidence of 5% for the younger and 18% for the older examined group (= increase of tooth surfaces with erosion). Prevalence data indicated that males had somewhat more erosive tooth wear than females. The distribution of erosion showed a predominance of occlusal surfaces (especially mandibular first molars), followed by facial surfaces (anterior maxillary teeth). Oral erosion was frequently found on maxillary incisors and canines. Overall, prevalence data are not homogeneous. Nevertheless, there is already a trend for more pronounced rate of erosion in younger age groups. Therefore, it is important to detect at-risk patients early to initiate adequate preventive measures.

Erosion—diagnosis and risk factors

Dental erosion is a multifactorial condition: The interplay of chemical, biological and behavioural factors is crucial and helps explain why some individuals exhibit more erosion than others. The erosive potential of erosive agents like acidic drinks or foodstuffs depends on chemical factors, e.g. pH, titratable acidity, mineral content, clearance on tooth surface and on its calcium-chelation properties. Biological factors such as saliva, acquired pellicle, tooth structure and positioning in relation to soft tissues and tongue are related to the pathogenesis of dental erosion. Furthermore, behavioural factors like eating and drinking habits, regular exercise with dehydration and decrease of salivary flow, excessive oral hygiene and, on the other side, an unhealthy lifestyle, e.g. chronic alcoholism, are predisposing factors for dental erosion. There is some evidence that dental erosion is growing steadily. To prevent further progression, it is important to detect this condition as early as possible. Dentists have to know the clinical appearance and possible signs of progression of erosive lesions and their causes such that adequate preventive and, if necessary, therapeutic measures can be initiated. The clinical examination has to be done systematically, and a comprehensive case history should be undertaken such that all risk factors will be revealed.

Prediction of the erosive potential of some beverages.

The aim of this study was to investigate whether the erosive potential of a beverage on human enamel can be predicted by examining the composition of the beverage. The buccal surfaces of 84 caries-free premolars were embedded in resin and polished flat. Two hundred micrometers of the enamel surface were removed. Then the slabs were divided into 14 groups and immersed for 20 min in commercially available beverages. Surface microhardness was measured before and after immersion. Further, the phosphate concentration, the fluoride concentration, the baseline pH as well as the titrated amount of base to raise the pH to 7.0 of each beverage were determined. Surface microhardness values after immersion were calculated with an equation derived in a recent study and compared with the values measured in this investigation. Apple juice showed the greatest significant decrease (p < 0.05) in surface microhardness, followed by Schweppes, Orangina and Grapefruit soft drink. The smallest decrease in surface microhardness that was significant resulted from Fendant and Isostar orange. The mean absolute deviation of the calculated to the effective erosion was 7.1%, it ranged between 14.6% (apple juice) and 1.6% (Fendant). The data suggest the possibility of predicting erosion caused by a beverage with an accuracy of 7%. This information can be of value in the prevention of dental erosion.

Impact of Different Toothpastes on the Prevention of Erosion

The aim of the present study was to test the impact of different toothpastes on the prevention of erosion. Enamel demineralization and remineralization were monitored using surface microhardness (SMH) measurements. Human enamel specimens were treated following two different procedures: (1) incubation in toothpaste slurry followed by acid softening and artificial saliva exposure; (2) acid softening followed by incubation in toothpaste slurry and artificial saliva exposure. For the control procedure, toothpaste treatment was excluded. The following toothpastes were tested: Zendium, Sensodyne Proschmelz (Pronamel), Prodent Rocket Power, Meridol and Signal active. Normalized SMH values compared to the baseline (= 1.00) after 1-hour artificial saliva exposure for procedure 1 (respectively for procedure 2) were as follows (mean: 95% CI): Sensodyne Proschmelz 0.97: 0.93, 1.00 (0.92: 0.90, 0.94), Zendium 0.97: 0.94, 1.00 (0.89: 0.83, 0.95), Meridol 0.97: 0.94, 1.00 (0.94: 0.92, 0.96), Signal active 0.94: 0.91, 0.97 (0.95: 0.91, 0.99), Prodent Rocket Power 0.92: 0.90, 0.94 (0.93: 0.89, 0.97) and control 0.91: 0.88, 0.94. Further exposure to artificial saliva for up to 4 h showed no significant improvement of SMH. Regression analyses revealed a significant impact of the applied procedure. Incubation in toothpaste slurries before the acid challenge seems to be favorable to prevent erosion. None of the tested toothpastes showed statistically significant better protection than another against an erosive attack.

Extrinsic causes of erosion. Diet. Chemical factors

pH value, calcium, and phosphate and to a lesser extent fluoride content of a drink or foodstuff are important factors explaining erosive attack. They determine the degree of saturation with respect to tooth minerals, which is the driving force for dissolution. Solutions oversaturated with respect to dental hard tissue will not dissolve it. Addition of calcium (and phosphate) salts to erosive drinks showed protection of surface softening. Today, several Ca-enriched soft drinks are on the market or products with naturally high content in Ca and P are available (such as yoghurt), which do not soften the dental hard tissue. The greater the buffering capacity of the drink or food, the longer it will take for the saliva to neutralize the acid. The buffer capacity of a solution has a distinct effect on the erosive attack when the solution remains adjacent to the tooth surface and is not replaced by saliva. A higher buffer capacity of a drink or foodstuff will enhance the processes of dissolution because more ions from the tooth mineral are needed to render the acid inactive for further demineralization. Further, the amount of drink in the mouth in relation to the amount of saliva present will modify the process of dissolution. There is no clear-cut critical pH for erosion as there is for caries. Even at a low pH, it is possible that other factors are strong enough to prevent erosion.

Restorative therapy of erosion.

When substance loss caused by erosive tooth wear reaches a certain degree, oral rehabilitation becomes necessary. Prior to the most recent decade, the severely eroded dentition could only be rehabilitated by the provision of extensive crown and bridge work or removable overdentures. As a result of the improvements in composite restorative materials, and in adhesive techniques, it has become possible to rehabilitate eroded dentitions in a less invasive manner. However, even today advanced erosive destruction requires the placement of more extensive restorations such as ceramic veneers or overlays and crowns. It has to be kept in mind that the etiology of the erosive lesions needs to be determined in order to halt the disease, otherwise the erosive process will continue to destroy tooth substance. This overview presents aspects concerning the restorative materials as well as the treatment options available to rehabilitate patients with erosion, from minimally invasive direct composite reconstructions to adhesively retained all-ceramic restorations. Restorative treatment is dependent on individual circumstances and the perceived needs and concerns of the patient. Long-term success is only possible when the cause is eliminated. In all situations, the restorative preparations have to follow the principles of minimally invasive treatment.

Effect of amine/sodium fluoride rinsing on toothbrush abrasion of softened enamel in situ.

The aim of this study was to test the effect of fluoride rinsing on the prevention of toothbrush abrasion of softened enamel in situ. For softening, the samples were immersed in 0.1 M citric acid (pH 3.5) for 3 min. Eight test subjects had to make 5 runs in which 4 slabs per run were attached to intraoral appliances. They were as follows: (1) no softening, no fluoride rinsing (control 1); (2) softening, no fluoride rinsing (control 2); (3) softening, rinsing in situ with a sodium/amine fluoride rinsing solution (250 ppm F) for 30 s; (4) rinsing in situ with the sodium/amine fluoride rinsing solution (250 ppm F) for 30 s, softening; (5) softening, rinsing in situ with an experimental amine fluoride-containing rinsing solution (250 ppm F) for 30 s. After exposure for 60 min to the oral milieu, the volunteers brushed the samples for 30 s with toothpaste and the loss of tooth substance was determined. For each test person, the secretion rate of resting and paraffin-stimulated saliva, buffering capacity and pH were measured. Toothbrush abrasion in situ was not significantly lower using the fluoride rinsing solutions before or after softening the enamel compared to no rinsing (p > 0.05). Multiple linear regression analyses revealed that 57% of the variation in toothbrush abrasion could be attributed to the severity of softening (p < 0.001) and the pH of stimulated saliva (p < 0.001). It was concluded that a single rinse for 30 s had no statistically significant effect on the prevention of toothbrush abrasion of softened enamel.

Diet and dental erosion.

Dental erosion (erosive tooth wear) is the result of a pathologic, chronic, localized loss of dental hard tissue that is chemically etched away from the tooth surface by acid and/or chelation without bacterial involvement. Acids of intrinsic (gastrointestinal) and extrinsic (dietary and environmental) origin are the main etiologic factors. Tooth wear including dental erosion is not a new phenomenon, but it is receiving increased attention because levels of dental caries have been decreasing in many industrialized societies. The prevalence of dental erosion changes with age and seems to depend on the society a person lives in, which could explain in part the large between-study variations (for a review, see Nunn). The progression (severity?) of erosion seems to be greater in older (52 to 56 y) than in younger (32 to 36 y) adults and has a skewed distribution in which a small proportion of the population has the most severe levels of erosion and the majority has low levels of erosion. In the study by Lussi and Schaffner, the group with high progression (severity?) had the following significant differences compared with the group with small progression: intake of dietary acids (P 0.01), the buffering capacity of stimulated saliva (P 0.02), and the bristle stiffness of the toothbrush (P 0.01). The dietary habits of the high-progression group changed very little between the first and second examinations despite discussions with patients about the dangers of erosive foodstuffs. Overall, the high-progression group had four or more acid intakes per day. An intake frequency of the same magnitude has been associated with an increased risk for erosion in children. It is well known that acidic food and drink can soften dental hard tissues. In 2000, the consumption of soft drinks and fruit juices in England amounted to over 120 L per capita per year, representing on average of about 50% of the total individual fluid consumption (A. Rugg-Gunn, personal communication, 2001). The erosive activity of citric, malic, phosphoric, and other acids has been tested and demonstrated in many in vitro, in situ, and in vivo studies. Epidemiologic studies and numerous case reports have found diet to be an important etiologic factor for the development and progression of erosion. In one study, 391 randomly selected individuals were investigated for dental erosion. Data from interviews and multiple regression analyses associated the consumption of citrus fruits and fruit drinks with the presence of erosion of facial tooth surfaces (surfaces adjacent to the cheek and lip) and occlusal erosion (biting surfaces). Chronic vomiting appeared to be most decisive factor for erosion on tooth surfaces adjacent to the palate. A case-control study of 106 cases of erosion showed the same pattern with citrus fruits, soft or sport drinks, apple vinegar, and vomiting associated with dental erosion. Dietary acids most commonly affect the labial surface of the upper incisors (surfaces adjacent to the lips). This could be due to the slow clearance of acids at this site. Excessive consumption of acidic food and beverages may produce dental hard tissue erosion. However, chemical, biological, and behavioral factors influence the development of dental erosion and are summarized in Table I. When dental erosion is clinically detected or when there is indication for an increased risk, risk assessment should be undertaken. A very important part is the case history. However, chairside interviews are generally not sufficient to determine dietary habits leading to erosion because patients may be unaware of their acid ingestion. Therefore, it is advisable to have such patients monitor their complete dietary intake for 4 consecutive days, including a weekend day, because dietary habits during weekends can differ considerably from those during weekdays. Patients should record, in writing, the time, quality, and quantity of all ingestions including diet supplements such as vitamin C tablets or solutions, iron tonics, and acidic candies (excessive consumption of the latter combined with a low salivary buffering capacity may aggravate existing erosive lesions). The dietary record should be sent to the dentist before the next appointment to enable analysis. In addition to estimating the erosive potential of different foodstuffs and drinks and taking into account the various parameters mentioned above, the dentist should analyze the frequency of ingestion of acidic (and of sugar-containing) foodstuffs with main meals and in-between snacks and estimate the duration of the acid challenge. In summary, it is important to know how, how often, how much, and when a particular drink or foodstuff is ingested. If

Controlled Toothbrush Abrasion of Softened Human Enamel

The aim of this in vitro study was to compare toothbrush abrasion of softened enamel after brushing with two (soft and hard) toothbrushes. One hundred and fifty-six human enamel specimens were indented with a Knoop diamond. Salivary pellicle was formed in vitro over a period of 3 h. Erosive lesions were produced by means of 1% citric acid. A force-measuring device allowed a controlled toothbrushing force of 1.5 N. The specimens were brushed either in toothpaste slurry or with toothpaste in artificial saliva for 15 s. Enamel loss was calculated from the change in indentation depth of the same indent before and after abrasion. Mean surface losses (95% CI) were recorded in ten treatment groups: (1) soft toothbrush only [28 (17–39) nm]; (2) hard toothbrush only [25 (16–34) nm]; (3) soft toothbrush in Sensodyne MultiCare slurry [46 (27–65) nm]; (4) hard toothbrush in Sensodyne MultiCare slurry [45 (24–66) nm]; (5) soft toothbrush in Colgate sensation white slurry [71 (55–87) nm]; (6) hard toothbrush in Colgate sensation white slurry [85 (60–110) nm]; (7) soft toothbrush with Sensodyne MultiCare [48 (39–57) nm]; (8) hard toothbrush with Sensodyne MultiCare [40 (29–51) nm]; (9) soft toothbrush with Colgate sensation white [51 (37–65) nm]; (10) hard toothbrush with Colgate sensation white [52 (36–68) nm]. Neither soft nor hard toothbrushes produced significantly different toothbrush abrasion of softened human enamel in this model (p > 0.05).