6

Dental diagnosis and the oral medicine of toothwear

William G. Young and Colin Dawes

Examination of patient’s facial features, oral soft tissues and teeth (see Chapters 1 and 4) yields a set of observations. Before a dental diagnosis can be made, these observations have to be explained from the patient’s history and oral medicine. Four clinical cases of patients with moderate and severe toothwear are detailed in full later in this chapter to highlight their oral medicine ramifications and the importance of a detailed clinical history to better undertand all the aetiologies involved and facilitate formulation of a diagnosis. The clinical interview history is paramount in the diagnosis of toothwear given its often complex multifactorial aetiology. In no other oral condition are the history and oral medicine so important in formulating the diagnosis. This is not necessarily the case in the diagnosis of dental caries.

THE APPROACH

The dentist and the patient have to resolve five key questions:

• Why is the toothwear mild, moderate or severe?
• Is bruxism involved?
• Is abrasion involved?
• What are the sources of extrinsic or intrinsic acids?
• Why has saliva protection been lost?

MILD, MODERATE OR SEVERE TOOTHWEAR

The age of the patient helps explain why their wear is mild. In the mixed dentition phase, wear on the deciduous teeth may have been severe, yet that on the first permanent incisors and molars is mild. The patient’s gender associated more severe wear with males and less wear with females of the same age (Young 2001a). However, the patient’s lifestyle at that stage in their life, as a student, in an occupation or in retirement on the date of presentation determines whether their toothwear is mild, moderate or severe, more than their age. Severity of toothwear can be markedly affected by genetic and environmental influences on development (Khan et al. 2001). Parafunction and bruxism may affect the severity of occlusal toothwear, dental diagnosis and management of attrition (Khan et al. 1998). Historically, the severity of occlusal and approximal wear was strongly affected by abrasive particles in the diet (Young 1998). Contemporaneously, cervical wear is exaggerated by toothbrush abrasion. In the absence of saliva protection, any acidic food or drink will attack the teeth. The commonest sources are soft drinks and sports drinks containing ascorbic, citric and/or phosphoric acid as preservatives. Wines are also acidic (Young 2001a). Less commonly, gastric juice containing hydrochloric acid is regurgitated by patients with alcoholism, eating disorders and gastro-oesophageal reflux disease (GORD; Valena & Young 2002). Dry mouth (xerostomia) and enlarged major salivary glands (sialadenosis) are key symptoms and signs requiring an oral medicine explanation. Dehydration, from exertion in sports or at the workplace, is the commonest cause of lost saliva protection in healthy patients of all ages and gender with toothwear (Young 2001a). Alcohol, drugs and medications also cause dry mouth and sialadenosis (Friedlander et al. 2003).

For a variety of reasons, saliva protection is defective in the following common conditions:

• Asthma
• Depression
• Diabetes mellitus
• Hypertension
• Sjögren’s syndrome

COMPLAINT/DISCOVERY

The complaint by which excessive toothwear comes to the patient’s attention is rarely dramatic (Box 6.1). The teeth may be rough, chip easily or appear shorter than normal. Fillings have high, sharp margins or even fall out. Worn teeth are sensitive some time after drinking soft drinks, but not after sugary foods. Episodic hypersensitivity may develop into near- and frank exposures, necessitating root canal therapy.

These signs and symptoms give a history quite different from that of dental decay. The patient needs to understand the essential differences between acid wear and dental caries for the severity of the signs and symptoms strongly influence the patient’s perception of their problem and what they want done about it. The patient is reassured when their complaints result from acid wear and not dental decay. It is not an infection and can be treated by less invasive and less costly techniques if identified in its early stages.

DEVELOPMENT

There is a common misconception that patients inherit genetically ‘soft teeth’. Patients need to be told that they have toothwear or dental decay and that this is not because they have inherited soft teeth. In fact, the surfaces most affected by occlusal attrition and erosion are enamel surfaces that have evolved as the strongest to resist wear throughout a lifetime. Teeth develop in the early years of life. Only rarely do they carry the marks of adverse genetics or environmental influences from these early years. Toothwear is only marginally influenced by development, but some key considerations emerge (Box 6.2).

Teeth affected by amelogenesis and dentinogenesis imperfecta chip and wear more rapidly than normal (see Chapter 2). Hereditary absence of major salivary glands puts patients at risk of dental erosion. In Prader–Willi syndrome (PWS), a non-hereditable chromosomal abnormality, salivation is abnormal (Young et al. 2001). Down’s syndrome children have excessive salivation, but drugs used to control their behaviour shut off salivary protection (Bell et al. 2002). Such syndromes are, thus, associated with increased risks of both toothwear and dental caries. Excessive toothwear in other members of a family more likely reflect socio-economic factors and dietary preferences than a genetic predisposition.

Environment during the first 12 years of life gives a helpful guide to the climatic conditions that could have established food and drink preferences. Similarly, fluoride levels in the water supply during the first 12 years can influence the resistance against dental caries and perhaps acid wear. Potentially, fluoride supplements given by parents would have similar effects. Despite this, excessive toothwear can develop in teeth even when fluoridation has been optimal (Teo et al. 1997). Tetracycline-stained teeth have a tendency to chip with age, but wear is not excessive.

ATTRITION

It is an axiom that the hardest and toughest tissues of the body, enamel and dentine, have evolved to resist wear by attrition. Attrition by tooth-to-toothwear, in the absence of abrasive particles in the diet and in the absence of oral acids, is minimal in contemporary Westernised populations (Young 1998). However, when acids etch enamel and dentine, attritional wear facets develop at an early stage (see Chapter 2). Tooth clenching and grinding habits likewise exaggerate attritional facets. Bruxism can only be diagnosed from observed parafunctional habits, muscle strain, tongue indentations and pronounced linea alba. The habit cannot be inferred from attritional wear facets alone.

The items provided in Box 6.3 have to be considered.

The patient may be aware of clenching or grinding their teeth when concentrating or stressed during the day. Clenching or grinding during sleep has to be confirmed by a parent or partner. Mouth breathing and snoring do not count. Muscle or joint strain or tenderness on waking may indicate bruxism.

Bruxism may have been suspected or suggested to the patient as the cause of the attrition, erosion and degradation on their teeth. Occlusal adjustments, extensive restorations and splint therapy may have been given on the basis that bruxism alone was the cause of wear (Box 6.3).

ABRASION

Occupational tooth abrasion is largely of historical interest, being connected with work practices, habits and food preparation by archaic methods. However, this topic opens up the patient’s occupation, habits, recreation and creativity in a general way (Box 6.4). Insights emerge that throw light on unusual causes of toothwear. Gemstone polishing exposes teeth to industrial abrasive dusts of silica, carborundum and diamond. Musical instruments with the reed held in the mouth may be a factor. Sewing and cutting thread, opening hairpins or holding nails cause local abrasion. Stoneground flour is abrasive because of its silica content. Bread from this flour was historically a major cause of abrasion on the teeth before steel milling was introduced.

Stains from tobacco smoking were removed with abrasive ‘smoker’s toothpastes’. Some tooth-whitening preparations are abrasive and the effects of bleaches on enamel hardness have yet to be evaluated. In the past, a diagnosis of ‘pipe-stem abrasion’ was given to regional abrasions on anterior teeth where the pipe was held habitually. The chemicals and drugs in tobacco smoke may not necessarily affect saliva protection of the teeth.

Healthy patients with excessive toothwear are not commonly smokers. However, former smokers with toothwear may have high blood pressure and be on antihypertensive medication, which reduces salivary protection.

TOOTHBRUSHING

Toothbrushing with non-abrasive toothpaste is unlikely to cause damage to the hardest and toughest biopolymers of the body – enamel and dentine. But enamel and dentine softened by acids undergo toothbrush abrasion (Box 6.5). Clinicians can be reassured that toothbrushes and toothpastes developed for plaque control and gingival health are unlikely to damage tooth surfaces, unless the teeth have been softened by oral acids in the absence of salivary protection. Eroded dentine is sensitive. So, changing methods of toothbrushing or the applications of toothpastes, densensitising gels or fluoride treatments afford only temporary relief.

As sensitivity comes and goes with episodes of acute erosion and remission, obtundent toothpastes get used sporadically and are often abandoned as ineffective. Sensitivity is the best warning to the patient of an acid attack, and a loss of sensitivity is the best indicator of remineralisation and tooth repair by saliva.

Caution must be advised in brushing teeth soon after an incident of acid attack that has softened the enamel. Excessive brushing habits shed light on obsessive behaviour and fixation on oral hygiene, e.g. ten times a day for at least 5 min each time.

ORAL HYGIENE

Oral hygiene methods other than toothbrushing are important for the management of dentinal sensitivity and toothwear. The following insights are relevant (Box 6.6). Flossing helps sensitivity by removing impacted food and dental plaque. But excessive flossing may abrade sensitive dentine and cementum softened by acids. Chewing gum flavour stimulates salivary flow. Chewing and swallowing neutralise and clear acids from plaque and the teeth (Dawes 2004b). Patient, parental and social attitudes need to be addressed when recommending chewing gum for oral hygiene. Astringent, bactericidal mouthwashes used to combat mouth odour and dental caries precipitate protective salivary proteins. Patients complain of a ropey, whitish deposit in their mouth after using astringent toothpastes, gels and mouthwashes, which precipitate proteins from their saliva. Alcoholic and phenolic mouthwashes produce leukoedema. Excessive use of astringent may products is, therefore, contraindicated for patients with toothwear because the protective properties of saliva are compromised. Fluoride rinses and gel applications control bacterial plaque and dentinal sensitivity. By reducing the solubility of the calcium apatites of enamel and dentine, fluoride may also be protective against intrinsic and extrinsic acids. Remineralisation of enamel and dentine by saliva is the goal of acid wear management. Therapeutic remineralising preparations are still under evaluation (Dawes 2008).

DIET EROSION

The points stated in Box 6.7 require consideration. Citrus fruits are a good source of vitamin C and excellent for stimulating saliva flow. But sucking oranges and lemon wedges or drinking undiluted lemon juice causes etching (Kunzel et al. 2000). Vitamin C (ascorbic acid) as powder, chewable tablets or added to sports and soft drinks can cause acid wear (Giunta 1983). Citric acid is commonly added to fruit drinks, soft drinks, sports drinks and cordials which, if drunk when saliva is shut off, will etch unprotected teeth. Sports gels contain citric acid and sodium citrate, and together these buffer the gels to a low pH that etches teeth. Gel sticks to teeth where saliva has been shut off by sports dehydration.

Orthophosphoric acid is a common acid in both diet and regular colas. Guarana extract is equally as acidic as orthophosphoric acid in colas. Special diets for ‘health’ or slimming need evaluation. Slimming pills and laxatives cause dehydration. Vegetarian diets can cause erosion from acetic acids in vinegars, used to preserve fruit and vegetables.

GASTRIC EROSION

Saliva is essential for digestive health. Swallowing it protects and heals the upper digestive tract from GORD. Accordingly, indigestion, heartburn and sour mouthfuls are common symptoms of gastric upset and GORD. Gastroscopy or radiography is used to find gastritis or ulcers. Antacid self-medication is common. Proton pump inhibitor (PPI) medications not only relieve symptoms of GORD but also reduce saliva flow rates. Gastric acid reflux brings hydrochloric acid into the mouth, so its cause and frequency are important. Bulimia nervosa exposes the teeth to hydrochloric acid. Bulimics, with enlarged salivary glands and low salivary flow, develop dental erosion (Milosevic et al. 1997).

Alcohol is the most frequent cause of heartburn and acute and chronic gastritis. Chronic nocturnal acid regurgitation is found in alcoholics with chronic gastritis. Alcohol is dehydrating. Beer is not usually acidic, but wines and spirits mixed with soft drinks are. Erosion of the lingual surfaces of the lower anterior teeth is a good indicator of chronic GORD. Erosion of the lingual surfaces of lower incisors, canines and even premolars is found in alcoholics in whom nocturnal gastric acid reflux is common. Enlargement of the major salivary glands (sialadenosis) is also found (Box 6.8).

SPORTS AND SOCIAL

Sports- and work-related dehydration is the commonest risk factor for toothwear, because dehydration physiologically turns off salivary protection and increases thirst for acidic sports and soft drinks. The points given in Box 6.9 need consideration. Exertion in fitness programmes, dancing, training sessions and competitions result in frequent dehydration. Degrees of exercise-induced dehydration change from childhood to adolescence to adulthood. Sports- and work choices influence diet. Nutrition and fitness require water, minerals, carbohydrates, fats and proteins. Caffeine, alcohol and performance-enhancing drugs affect athletes and thirsty workers. Caffeine and alcohol addiction increase exposure to acids in colas, wines and spirits.

Many occupations involve dehydrating work conditions and exposure to acids. Examples include lemon and citrus farmers or battery manufacturers. Night-shift workers are at risk if they drink caffeine-containing acid soft drinks to keep themselves awake and are, thus, at risk of dental erosion, for saliva is shut off at night (Dawes 2004a).

MEDICAL

Medical conditions and treatments in which salivary protection of the teeth is lost put patients at risk of toothwear. The questions asked in Box 6.10 therefore require investigation. Systemic conditions asthma, diabetes mellitus and high blood pressure (hypertension) are common and particularly important. GORD is common in asthmatics.

There are thousands of medications that shut off saliva or are acidic. The side effects of dry mouth (xerostomia) and sialadenosis are often found to be caused by alcohol, dehydration, systemic condition or medication. Xerostomia is experienced when saliva is lacki/>