The effect of remineralizing solutions on tooth wear in vitro

The erosive effects of saliva following chewing gum on enamel and dentine: an ex vivo study

OBJECTIVES

The primary objective was to determine the erosive effect of expectorated saliva, following chewing acidic gum, on enamel and dentine samples, using a non-acidic gum as a negative control. Secondary objectives were to determine the effect of brushing enamel and dentine samples and the effect of individual saliva pH and buffering.

DESIGN

A single-centre, single-blind, placebo-controlled, two-way crossover study.

SETTING

A clinical trial, involving healthy participants, undertaken at Bristol Dental School and Hospital.

METHODS

Eight healthy participants expectorated saliva onto prepared enamel and dentine samples while chewing gum (strawberry flavoured acidic gum [active] or peppermint flavoured non-acidic gum [control]). Half of the enamel and dentine samples were brushed before measurement by contact profilometry.

MAIN OUTCOME MEASURES

Mean enamel and dentine erosion, with and without brushing and the relationship to salivary buffering.Results At 10 days, mean depth of surface loss from dentine samples (95% CI), following chewing of acid-containing gum and subsequent brushing, was -11.34 μm (2.22 μm) and from un-brushed dentine samples was -11.02 μm (1.71 μm). No significant erosion was noted for other groups.

CONCLUSIONS

Frequent chewers of acid-containing gums are susceptible to dentine erosion even in the presence of good salivary buffering. Enamel erosion was insignificant within the time constraints of the present study but warrants further investigation.

The cervical wedge-shaped lesion in teeth: a light and electron microscopic study

BACKGROUND

The cervical non-carious wedged-shaped lesion is controversial in that its aetiology may involve attrition, erosion, abrasion and stress-corrosion (abfraction). This study examined the histopathology of anterior teeth with cervical wedge-shaped lesions by light and electron microscopy to elucidate their pathogenesis.

METHODS

Ten undecalcified human teeth with cervical lesions were available for investigation. Patency of the dentine tubules was tested using red dye penetration from the pulp chamber. The morphology of normal and sclerotic dentine adjacent to the cervical wedge-shaped lesions was investigated by scanning electron microscopy. The numbers and diameters of dentinal tubules were measured at different levels beneath the surfaces of the lesions.

RESULTS

The gross and microscopic features of the worn teeth were described. Red dye penetration tests showed white tracts of sclerotic tubules contrasted with red tracts of patent tubules. Numbers of tubules per square area and diameters of patent and sclerotic tubules varied at different levels within the dentine due to deposits of intratubular dentine.

CONCLUSIONS

The cervical wedge is shaped by interactions between acid wear, abrasion and dentinal sclerosis. No histopathological evidence of abfraction was found. Clinical diagnosis, conservation and restoration of non-carious cervical lesions need to take into account the extent of sclerotic dentine beneath wedge-shaped lesions.

Dental Erosion

There is some evidence that dental erosion is steadily spreading. To diagnose erosion, dental professionals have to rely on clinical appearance, as there is no device available to detect it. Adequate preventive measures can only be initiated if the different risk factors and potential interactions between them are known. 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 bridgework or removable dentures. 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.

A critical review of non-carious cervical (wear) lesions and the role of abfraction, erosion, and abrasion

The terms 'abfraction' and 'abrasion' describe the cause of lesions found along the cervical margins of teeth. Erosion, abrasion, and attrition have all been associated with their formation. Early research suggested that the cause of the V-shaped lesion was excessive horizontal toothbrushing. Abfraction is another possible etiology and involves occlusal stress, producing cervical cracks that predispose the surface to erosion and abrasion. This article critically reviews the literature on abrasion, erosion, and abrasion, and abfraction. The references were obtained by a MEDLINE search in March, 2005, and from this, hand searches were undertaken. From the literature, there is little evidence, apart from laboratory studies, to indicate that abfraction exists other than as a hypothetical component of cervical wear.

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.

Dental erosion in a group of British 14-year-old, school children. Part III: Influence of oral hygiene practises

OBJECTIVES

The aims of this study were firstly to describe the dental history and oral hygiene practises in a cluster random sample of 14-year-old children in Birmingham, UK. The second aim was to determine whether the oral hygiene practises are associated with dental erosion.

METHOD

A total of 418, 14-year-old schoolchildren from a cluster random sample in Birmingham, UK were assessed for dental erosion (209 males and 209 females). Data on the dental history and oral hygiene practises were obtained from a self-reported questionnaire supplemented by a structured interview. The data were analysed using SPSS with Mann-Whitney U analyses and odds ratios.

RESULTS

74% of the teenagers claimed to attend the dentist on a six-monthly basis; 60% brushed their teeth twice a day ie before breakfast and last thing at night, 25% once a day, 12% three times or more a day and 3% less than once a day. It was a so found that 28% of the children brushed their teeth after meals; 92% of the children used a manual toothbrush and 56% of them replaced their toothbrush every three-months. The most common technique used by the children was a circular brushing movement; 44% of them used a mouthwash and 40% used other interdental cleaning. Girls brushed their teeth more frequently than boys. Associations were found between dental erosion and brushing teeth last thing at night, after meals, techniques of brushing teeth, and type of toothbrush and frequency of brushing. It was concluded that reported oral hygiene practises in teenage schoolchildren in Birmingham, UK complied with generally recommended guidelines. However, there was an association between dental erosion and some of these oral hygiene practises. Advice concerning the impact of some oral hygiene procedures needs to be given to those who are susceptible to dental erosion.

Structured review of enamel erosion literature (1980-1998): a critical appraisal of experimental, clinical and review publications

OBJECTIVE

To attain an objective account of the methods to measure enamel erosion used in 1980-1998 publications, a structured review of the literature was undertaken.

METHODS

Inclusion and exclusion criteria were applied to 731 clinical/experimental research and review reports. Eighty-five included papers were subsequently rated according to 'hierarchy of evidence' guidelines to assess the strength of the report's design and the relevance of the evidence to replicating enamel erosion in vivo in humans. Scores were assigned to rate each aspect in the guidelines.

RESULTS

A total of 16 clinical, 13 review and 56 experimental papers were assessed; 36.4% were published during 1996-1998. Excluding reviews, 16 papers were qualitative and 56 quantitative; 51 used human enamel. Our classification yielded nine groups of methods (five scoring systems and 26 measurement techniques). CTFPHE (Can Med Assoc J 1992; 147: 443) grading of research reports indicated that 2.8% provided evidence grade I; 20.8%, grade IIa; 63.9%, grade III; and 12.5%, grade IV.

CONCLUSIONS

There has been a consistent increase in the body of knowledge. The overall quality of publications has not substantially changed over time. Experimental studies were more often quantitative, and quantitative studies had better research designs. No single group of research methods had obviously superior research designs.

Dental cervical lesions associated with occlusal erosion and attrition

Acid demineralization of teeth causes occlusal erosion and attrition, and shallow and wedge-shaped cervical lesions putatively involving abfraction. From 250 patients with tooth wear, 122 with cervical lesions were identified. From epoxy resin replicas of their dentitions, associations of occlusal attrition or erosion or no wear with cervical lesions were recorded at 24 tooth sites (total 2928 sites). Criteria used to discriminate occlusal attrition from erosion, and shallow from grooved, wedge-shaped or restored cervical lesions were delineated by scanning electron microscopy. A 96 per cent association was found between occlusal and cervical pathology. Shallow cervical lesions were more commonly found in association with occlusal erosion. Wedge-shaped lesions were found equally commonly in association with occlusal erosion, as with attrition. Grooved and restored cervical lesions were uncommon. Differences were appreciated in the associations within incisor, canine, premolar and molar tooth sites which related more to the site-specificity of dental erosion than to attrition from occlusal forces. Non-carious lesions on teeth then have multifactorial aetiology and pathogenesis in which erosion and salivary protection play central roles. Dentists should primarily consider erosion in the diagnosis, prevention and treatment of tooth wear.

Dental erosion

Tooth enamel erosion occurs only in susceptible individuals regardless of food and beverage consumption patterns, that is, consumption of an acidic drink or food alone is highly unlikely to cause erosion. Susceptibility is highly variable from person to person and multifactorial in nature, as are the causes of erosion itself. Tooth enamel erosion is relatively rare and is easily misdiagnosed. A thorough differential diagnosis that eliminates the many other possible causes of enamel loss must be conducted. It is important to distinguish dental erosion from dental caries. Although the end result is similar, these two pathologies rarely occur simultaneously at the same site. In cases of true erosion, the tooth enamel is demineralised by direct contact with acids, while caries is a disease that occurs by the action of acids produced by plaque biofilm micro-organisms. It should also be stressed, clinically speaking, that erosion is primarily a surface phenomenon, while caries generally begins as a subsurface demineralisation of enamel structure that eventually leads to a pit in the tooth surface. As tooth enamel erosion is relatively rare, and the result of many factors, further research is needed to determine why susceptibility to erosion differs so widely from person to person.

Etiology of dental erosion--extrinsic factors

The extrinsic causes of dental erosion can be grouped under the headings of environmental, diet, medications and lifestyle. Environmental factors mainly involve exposure to acid fumes by workers in factories without proper safeguards. Swimming pools with low pH due to inadequate maintenance have also been implicated. Dietary factors have received the most attention and are likely to affect the broadest segment of the population. Most acidic foods and drinks have the potential to cause dental erosion in the human mouth. The total acid level (titratable acid) of dietary substances is considered more important than their pH, because it will determine the actual H+ available to interact with the tooth surface. Other constituents of foods and beverages will also have a modifying effect, including the calcium, phosphate and fluoride concentration, the acid type, and physical and chemical properties that influence the clearance rate from the mouth. It is not appropriate to assign relative degrees of risk to the different dietary substances except in general categories, because of the many human biological and behavioral factors that influence the clinical expression of dental erosion. The types of foods and beverages consumed, and the frequency and time of consumption are lifestyle factors that are considered most important regarding the clinical development of dental erosion. Low pH medications and oral hygiene products have also been suggested as potential causes of erosion. The combination of frequent consumption of acidic substances and overzealous oral hygiene practices may be another high risk lifestyle factor.

The distribution and severity of tooth wear and the relationship between erosion and dietary constituents in a group of children

There is very little published information on the severity of tooth wear in children. The current investigation involved clinical examination of 101 children and an assessment of their dietary habits. Evidence of tooth wear was found in over 80% of maxillary incisor teeth, and 30% of primary molar teeth had some dentine exposed. There were 21 children who were regarded as having 'mild' erosion, 45 'moderate' erosion and 35 'severe' erosion. There were highly statistically significant differences between the three groups in relation to drinking habits; the mean number of carbonated drinks consumed per week by children in the 'mild', 'moderate' and 'severe' erosion groups was 3.9, 5.8 and 13.9 respectively, of fruit drinks 10.3, 16.4 and 18.3, and of all fruit-based drinks 17.9, 27.1 and 39.0. There were also highly significant differences in those having a fruit-based drink at bed-time; 14% in the 'mild' erosion group, 32% in the 'moderate' and 60% in the 'severe' group. Although fresh fruit and yoghurt consumption followed the same trend, this did not reveal statistically significant differences. It is important to identify children who exhibit clinical evidence of erosion so that advice can be given about consumption of acidic dietary constituents.