Grading of facial surfaces

Grade 0: No erosion. Surface with a smooth, silky-shining appearance, absence of developmental ridges possible.

Grade 1: Loss of surface enamel. Intact enamel found cervical to the lesion. Concavity in enamel, the width of which clearly exceeds its depth, thus distinguishing it from toothbrush abrasion. Undulating borders of the lesions are possible.

Dentin is not involved (Fig. 1).

Grade 2: Involvement of dentin for less than one half of the tooth surface. (Figs. 1, 2, 3).

Grade 3: Involvement of dentin for more than one half of the tooth surface.

Grading of oral and occlusal surfaces

Grade 0: No erosion. Surface with a smooth, silky-shining appearance. Absence of developmental ridges possible.

Grade 1: Slight erosion, rounded cusps, edges of restorations rising above the level of adjacent tooth surface, grooves on occlusal aspects. Loss of surface enamel. Dentin is not involved (Fig. 4).

Grade 2: Severe erosion, more pronounced signs than in grade 1. Dentin is involved (Figs. 5 – 9).

Erosive lesions have to be clearly distinguished from wedge-shaped defects. There is evidence that incorrect toothbrushing techniques may traumatise these tissues and lead to gingival recession with root surface exposure and cervical wedge-shaped defects often called toothbrush abrasions (4). In this context it should be mentioned that physical loading during interocclusal activities has also been discussed as one possible factor contributing to the formation of wedge-shaped defects. While true erosion is mainly caused by the action of acids and assisted by abrasion or attrition, wedge-shaped defects are primarily caused by abrasion (and occlusal stress) and only secondarily aggravated by acid softening of the hard tissue. Since the etiology as well as the prevention of wedge-shaped defects are different from those of erosive lesions, it is important that the dentist is able to distinguish between these conditions.

Prevention

When dental erosion is clinically detected or when there is indication of an increased risk, detailed patient assessment should be undertaken. A very important part is case history taking. However, chair-side interviews are generally not sufficient to determine dietary habits leading to erosion because the patients may be unaware of their acid ingestion. It is therefore advisable to have such patients record in writing their complete dietary intake for four consecutive days (Table 1). The time of day and quantity of all ingested food and beverages, including dietary supplements, should be recorded. Both weekdays and weekends should be included, as dietary habits during weekends may be considerably different from those during weekdays. This dietary and behaviour record should be sent to the dentist prior to the next appointment. The dentist should determine the erosive potential of the different acidic food items and drinks, the frequency of ingestion during main meals and snacks followed by an estimation of the daily acid challenge. It has also to be taken into account possible intrinsic acid exposure. As not all possible risk factors are recorded during these four days the patient should be questioned specifically and examined using the information provided in Table 2. Based on these analyses, a useable preventive program may be suggested to patients on an individual basis (Table 3). The goal of this program is to reduce acid exposure by decreasing the frequency of ingestion of potentially harmful drinks and foodstuffs as well as minimising contact time by rapid consumption rather than sipping or swishing or by controlling reflux/vomiting. The patient’s fluoride regime should be optimised. As discussed, various pathological processes cause the degradation of tooth substance. Erosion, attrition and abrasion often occur simultaneously, even though one of these factors may be predominant. When giving preventive instructions, all the causative components must be taken into consideration. Other behaviours that either stimulate salivary flow such as chewing gum or directly help to neutralise acids such as rinsing with sodium bicarbonate may counteract the destructive effects of dietary acids (5). Patients suffering from intrinsic erosions need, depending upon the cause, further care such as psychological therapy, antacida or even surgical intervention.

Acid-eroded enamel is more susceptible to abrasion and attrition than intact enamel. The thickness of the softened enamel that is removed after different abrasion procedures varies in different investigations depending on experimental conditions (for a review see 6). It appears that highly concentrated fluoride gels showed the best protection against further erosion/abrasion (7 – 9).

Experiments

In our own experiments we compared the impact of different fluoride procedures on the prevention of toothbrush abrasion of softened enamel when applied before softening. Softening was made in vitro with 0.1 M citric acid (pH 3.5) during 3 min. All runs were performed in which 4 slabs per run were attached to intraoral appliances. After exposing for 60 minutes to the oral milieu, the samples were brushed in situ for 15 s with a medium abrasive toothpaste and the loss of tooth substance was determined (Fig. 12). Toothbrush abrasion was lowest using the slightly acidic sodium/amine fluoride gel for 1 min before softening the enamel compared to all the other experimental groups (p<0.05). This could be due to some incorporation of material into and/or deposition of material on the enamel, most probably as a CaF₂-like material (7, 8). There was no significant protecive effect in our experiment when Solidox Syreblokk® (Lilleborg as) was used. For individuals with a high risk for erosive tooth wear and with active erosion we suggest to postpone tooth brushing at least for one hour after consuming erosive foodstuffs or beverages in order to minimise enamel loss. Another possibility is the application of fluoride before the erosive attack (Fig. 12). For patients prone to caries, the risk of enhancing the progression of carious lesions by postponing tooth brushing may be too high because of the rapid decrease in plaque pH after ingestion of sugar-containing foods or beverages. Measures that would be both beneficial for erosion and caries would be rinsing with fluoride solutions to enhance remineralisation and chewing sugarless gum to stimulate the secretion of saliva.

Minimally invasive treatment

Early diagnosis of the process is a prerequisite to start preventive measures and to prevent every restoration. In no case may early diagnosis be an excuse for a restoration. The initiation of restorative treatment has to depend on individual circumstances and the perceived needs and concern of the patient.

The very first minimally invasive measure is the sealing of the tooth surface. In a study (10) the sealer/bonding products «Seal and Protect» and «Optibond Solo» were applied each to extracted teeth and subjected to 3 000 cycles in an erosion/abrasion wear machine. The amount of wear measured on the unprotected teeth was 243 m whereas on the protected surfaces it measured 24.8 m for «Seal and Protect» and 1.4 m for «Optibond Solo». It was concluded that both products protected the teeth in this wear regime and the technique could be used clinically for patients. Our own clinical experience shows an obvious decrease of hypersensitivity of erosive damaged teeth after sealing. However, the sealing procedures have to be repeated periodically.

Occlusal erosions typically show grooves on occlusal aspects and edges of restorations rising above the level of adjacent tooth surfaces. These grooves show a prolonged time of a depressed pH value after an acid attack (unpublished observation) which will lead to further progression of the erosive process at this site. In such cases minimally invasive composite fillings are able to protect the affected region (11). Conventional glass-ionomer cements are not recommended as permanent restorations because of their disintegration in acidic conditions (12). Advanced destructions will need more extensive restorations made of composite, ceramic veneers or even onlays or crowns. In all cases, the preparations have to follow the principles of minimally invasive treatment. It has to be kept in mind that the causes of the lesions have to be detected in order to stop the disease. Otherwise, the erosive process will further destroy tooth substance (Fig. 9 – 11).