• Asthma;
  • beta-2 agonist;
  • dental caries;
  • dental erosion;
  • inhaled corticosteroids;
  • oral candidiasis;
  • periodontal disease;
  • salivary flow


  1. Top of page
  2. Abstract
  3. Introduction
  4. Conclusions
  5. References

Asthma is a chronic inflammatory condition that causes the airways to constrict and produce excess mucus, making breathing difficult. It is characterized by the obstruction of airflow which is variable over a short period of time. This condition is reversible, either spontaneously or can be controlled with the help of drugs. Asthma medication comprises bronchodilators, corticosteroids and anticholinergic drugs. Most of these drugs are inhaled using various forms of inhalers or nebulizers. The effect of these drugs on oral health is the subject of debate among dental practitioners. Patients taking asthma medication may be at risk of dental caries, dental erosion, periodontal diseases and oral candidiasis. Hence, patients with bronchial asthma on medication should receive special prophylactic attention. This article reviews the correlation between asthma and oral health, and suggests various measures to counter possible oral health problems related to asthma.

Abbreviations and acronyms:

gastro-oesophageal reflux


inhaled corticosteroids


  1. Top of page
  2. Abstract
  3. Introduction
  4. Conclusions
  5. References

Asthma is a growing public health problem affecting over 300 million people worldwide. It is estimated that an additional 100 million may be diagnosed with asthma by 2025.1 Asthma is characterized by chronic airway inflammation and increased airway hyper-responsiveness, leading to symptoms such as wheezing, coughing, chest tightness and dyspnoea. It is characterized by the obstruction of airflow which varies over a short period of time and is reversible, either spontaneously or with treatment.

Asthma treatment has two main objectives: to control, as well as to reduce the airway inflammation, and reopen the airways. Drugs that achieve the first objective are called anti-inflammatory agents and those that achieve the second are called bronchodilators. Asthma medication falls into two categories: quick relief medication and long-term control medication. Quick relief medication comprises of short-acting bronchodilators, systemic corticosteroids and anticholinergic drugs. Long-term control medication includes anti-inflammatory agents, long-acting bronchodilators and leukotriene modifiers.1 Most asthma drugs are inhaled using various forms of inhalers or nebulizers. Patients should be carefully trained in the use of inhalers for these to be effective. Patients should also be instructed to use inhalers regularly as prescribed. Inhalers which deliver these medicaments may be used up to four times a day over a long period. As the prevalence of asthma is on the rise, the problems caused by asthma medication could result in a significant worldwide dental health problem. Therefore, it is necessary to scrutinize the effects of asthma and its medication on oral health.

Studies show that prolonged use of beta-2 agonist can reduce salivary flow.2,3 Ryberg et al.3 observed that the secretion rates of whole and parotid saliva decreased by 26% and 36%, respectively, in asthmatics on medication when compared to the non-asthmatic control group. Asthmatic subjects also showed a decrease in output per minute of total protein, amylase, hexosamine, salivary peroxidase, lysozyme and secretory IgA in stimulated parotid saliva.4 Any factor which reduces the quality and quantity of saliva can negatively affect oral health because saliva plays an important role in its preservation (Table 1).5

Table 1.   Role of saliva in preservation of oral health
FunctionComponent responsibleMode of protection
Lubrication and maintenance of mucosal integrityMucin, proline-rich glycoproteins, water• Forms a seromucosal covering that lubricates and protects the oral tissues against irritating agents • Modulates the adhesion of micro-organisms to the oral tissue surfaces which contributes to the control of bacterial and fungal colonization
Cleansing and dilutionWater• Cleanses the residues present in the mouth such as non-adherent bacteria, cellular and food debris • Salivary flow eliminates excess carbohydrate, thus limiting the availability of sugars to the micro-organisms
Buffering capacity and remineralizationBicarbonate, phosphate, calcium, statherin, proline-rich anionic proteins, fluoride• Maintains the physical-chemical integrity of tooth enamel by modulating remineralization and demineralization • Buffers (neutralizes) the acids produced by acidogenic micro-organisms, thus preventing enamel demineralization
Antimicrobial actionIgA, immunoglobulins, proline-rich glycoproteins Lysozyme, lactoferrin, lactoperoxidase, mucins, cysteine, histatins• Inhibits microbial adhesion to oral tissues • Prevents proliferation of micro-organisms

The association of asthma with oral conditions such as dental caries, dental erosion, periodontal diseases and oral mucosal changes has been the subject of debate among dental practitioners.6 This article reviews the correlation between asthma and oral health, and suggests various measures to counter possible oral health problems related to asthma (Table 2).

Table 2.   Possible causes for the increase in prevalence of oral health problems in asthmatics and various measures to prevent these problems
Oral health conditionPossible causesPrecautionary measures
Dental caries• Decrease salivary flow rate caused by beta-2 agonist • Increase in Lactobacilli and Streptococcusmutans count • Decrease in the salivary and plaque pH due to the use of inhalers • Fermentable carbohydrate present in anti-asthma medications • Increase in the frequency of consumption of cariogenic drinks• Educate asthmatic patients about their susceptibility to oral health problems • Encourage regular dental check-ups • Advocate precautionary oral hygiene practices • Adopt caries preventive measures (fluoride supplements and pit and fissure sealants) • Advise the use of antimicrobial mouth washes • Advise the patients to rinse the mouth immediately after using an inhaler • Encourage patients to drink water more often to counteract dry mouth • Prescribe sugar-free chewing gum to increase salivary output • Train patients to use their inhaler properly • Provide spacer device to deliver the inhaled drugs directly to the airway • Refer to a gastroenterologist to rule out gastrointestinal disease • Administer lowest possible dose of inhaled corticosteroids • Prescribe topical antimycotics to prevent oral candidiasis
Dental erosion• Reduction in the buffering capacity and salivary flow rate due to beta-2 agonist • Increase in the exposure of teeth to acids    • Extrinsic source – Acidic soft drinks      – Acidity of medication    • Intrinsic source – Gastro-oesophageal reflux
Periodontal disease• Decrease in salivary protection due to the reduction in salivary flow and concentration of secretory IgA • Dehydration of alveolar mucosa due to mouth breathing • Alteration of immune response and increase concentration of IgE in gingival tissue • Higher incidence of calculus due to increased levels of calcium and phosphorous in saliva. • Decrease in bone mineral density associated with inhaled corticosteroids
Oral candidiasis• Generalized immunosuppressive and anti-inflammatory effects of steroids • Higher salivary glucose concentration that could promote growth and proliferation of Candida • Low salivary flow rate

Asthma and dental caries

McDerra et al.7 pointed out that asthmatic children have more tooth decay affecting permanent teeth. A study by Reddy et al.8 suggested that asthmatic children have a high prevalence of caries and this increases with the severity of bronchial asthma. Ersin et al.9 showed that asthma, through its disease status and its pharmacotherapy, includes some risk factors such as a decrease in the salivary flow rate and salivary pH for caries development. They also demonstrated that the duration of medication and illness has a significant influence on the risk of developing caries in asthmatics. Shashikiran and co-workers10 revealed that asthmatic patients, especially those using salbutamol inhalers, have more caries than the control group. The results of a study by Stensson et al.11 also indicated that preschool children with asthma have a higher prevalence of caries than children without asthma. Factors leading to this may be due to a higher intake of sugary drinks and mouth breathing.

In contrast to the above mentioned studies, there are other studies that do not demonstrate a positive correlation between asthma and dental caries. Bjerkeborn et al.12 showed that neither asthma per se nor disease severity affects the prevalence of caries in asthmatic children. A study by Eloot et al.13 also did not recognize any connection between the severity of the asthma, the period of exposure to medication and the prevalence of caries.

Ryberg et al.2 stated that the increase in risk of dental caries in asthmatic children medicated with beta-2 agonist was most often associated with a decrease in the salivary flow rate and the increase in Lactobacilli and Streptococcus mutans. This diminished flow rate can jeopardize the protective ability of the saliva to clear the oral cavity of fermentable substances and also decrease its buffering capacity. Kargul et al.14 showed a significant decrease in the pH of saliva and plaque, below the critical value for enamel demineralization of 5.5 in asthmatic children, 30 minutes after treatment with beta-2 agonist inhalers.

The reason for a higher rate of caries observed in people with asthma can also be attributed to the presence of fermentable carbohydrate in asthma medications. Some dry powder inhalers contain sugar (lactose monohydrate) so that the patient can tolerate the taste of the drug when it is delivered. Frequent oral inhalation of these sugar-containing drugs, combined with a decrease in the salivary flow rate may contribute to an increased risk of caries. Kenny and Somaya15 stated that the long-term use of liquid oral medications containing sugar can lead to an increase in the caries rate. Reddy et al.8 pointed out that the highest caries prevalence in asthmatics is seen in those taking medications in syrup form.

Frequent consumption of cariogenic drinks due to excessive thirst can also be a reason for an increase in the caries rate in asthmatics. The increase in the intake of these drinks may be related to a number of factors: an attempt to wash away the taste of the inhaled medication; to counter the desiccating effect of mouth breathing and the reduction in the salivary flow caused by beta-2 agonist.11 In addition, asthmatic children may have a restricted lifestyle where they miss school and are not able to play sports and participate in other normal childhood activities. McDerra et al.7 reported that families may overindulge children with frequent consumption of sweets, leading to an increase in caries levels. Moreover, the increased attention to their general asthmatic condition may result in oral hygiene care being neglected.8

It is evident that oral prophylactic strategies can be used to address the increase in caries risk in asthmatics. These include an increase in the frequency of dental maintenance visits, fluoride interventions and adherence to caries-prevention measures. All age groups should be made aware of the problem and be encouraged to have regular dental check-ups. Fluoride supplements should be prescribed for all asthmatic patients, especially for those taking beta-2 agonists. Patients should be instructed to rinse their mouths after using an inhaler.6 They may also be advised to use saliva substitutes, sip plain water and use a fluoridated mouthrinse daily to compensate for xerostomia. A study by Kargul et al.14 showed that chewing sugar-free gum for at least one minute after using an inhaler can neutralize the interdental plaque pH. Therefore, the use of sugar-free chewing gum to stimulate salivary flow and buffer oral acids is encouraged.

Asthma and dental erosion

McDerra et al.,7 Al-Dlaigan et al.16 and Sivasuthamparam et al.17 reported that children with asthma are at an increased risk of developing dental erosion. However, a study by Dugmore and Rock18 yielded no clear association between asthma and dental erosion.

Asthma medication can place the patient at a risk of dental erosion by reducing salivary protection against extrinsic or intrinsic acids. Saliva is considered to be one of the main neutralizing factors in the pathogenesis of dental erosion. The oral clearance of dietary acid is related to the rate of secretion and buffering capacity of saliva. As mentioned earlier, studies have shown a lowered salivary flow rate in asthmatic subjects treated with beta-2 adrenoceptor agonists when compared to non-asthmatic groups.2 This reduction in the production of saliva can affect the natural way in which the mouth maintains its chemical balance. There can be an increased dryness of the mouth in asthmatics due to the effects of bronchodilators and/or mouth breathing. So it is possible that there will be an increase in the consumption of drinks to compensate oral dehydration. Often drinks with a low pH and high titratable acidity are consumed. This may result in dental erosion.16

There is evidence that medicines taken by a dry powder inhaler may cause tooth erosion by changing the chemical environment of the mouth. O’Sullivan et al.19 showed that the main asthmatic drugs in current use, especially the powdered drugs, have a pH less than the critical level of 5.5 required for hydroxyapatite dissolution. Even though, in a study by Tootla et al.,20 none of the inhalers demonstrated a clinically significant acidiogenic response, a drop in salivary pH and plaque pH was observed with a lactose-based dry powder inhaler. When used several times a day, these drugs may contribute to the dissolution of teeth.

Another possible explanation for acidic erosion of teeth in people with asthma is that they have an increased incidence of gastro-oesophageal reflux (GOR).21 The prevalence of reflux symptoms, oesophagitis and abnormal oesophageal acid is higher in patients with asthma than in the control population. Harding21 reported that GOR symptoms are more prevalent in asthmatic patients (approximately 75%) when compared to the control group. The oesophagus and the lungs interact through a variety of mechanisms. Oesophageal acid-induced bronchoconstriction can be provoked by a vagally mediated reflex, neural enhancement of bronchial reactivity or by microaspiration. Potential mechanisms whereby asthma may predispose to the development of GOR include autonomic dysregulation, an increase in the pressure gradient differential between thorax and abdomen, a high prevalence of hiatal hernia, and alterations in crural diaphragm function.21 Asthma medications may also be one of the factors that promote GOR development in asthmatics. Certain inhaled beta-2 adrenoreceptor drugs partly swallowed when used may decrease the lower oesophageal sphincter pressure and the oesophageal contraction amplitude. This relaxation is associated with GOR.16 The relationship between gastrointestinal disease and dental erosion is well documented.22 Hence an increased prevalence of GOR in asthmatics can provide a partial explanation of the relationship between asthma and dental erosion.

It is shown that dry powder inhalers used for asthma have an acidic pH. Therefore, patients can be encouraged to rinse their mouth immediately after using the inhaler with neutral pH or basic mouthrinses, such as liquid antacids, sodium bicarbonate in water, milk or neutral sodium fluoride mouthrinses.23 The use of a spacer device may also be of help in delivering the dose effectively into the lungs.19 Since evidence is strong that GOR plays an important role in some patients with asthma, presumptive diagnosis by the dentist should lead to appropriate referral for further investigation. Most often it will be to a gastroenterologist for gastroscopy and 24-hour measurement of oesophageal pH. Antacids should be prescribed to patients having gastrointestinal disorders.

Asthma and periodontal disease

Studies examining the association between periodontal diseases and asthma have reported varying results. Hyyppäet al.,24 McDeera et al.,7 Shashikiran et al.10 and Stensson et al.11 revealed that asthmatics have poorer periodontal health than the control population, whereas Bjerkeborn et al.12 and Eloot et al.13 did not find any difference in the prevalence of periodontal disease in asthmatics.

An association between asthma and periodontal disease may involve either pathological activation of the immune and inflammatory process, the side effect of the asthma medications, or the interaction between the two. Hyyppäet al.24 suggested that gingivitis in asthmatic children could be explained by an altered immune response and the dehydration of alveolar mucosa due to mouth breathing. The concentration of IgE in gingival tissue is found to be elevated in patients with asthma, which can also cause periodontal destruction.25 Interaction between bacterial and immunological factors are found to be the main cause of destruction of periodontal tissue. Saliva undoubtedly impacts this interaction through its protective mechanism. Since many asthma drugs modify salivary secretion in a significant percentage of patients, the periodontal health of these patients may be affected negatively.

McDeera et al.7 suggested that children with asthma have more calculus than normal children. Higher prevalence of calculus in asthmatic children is thought to be due to an increase in the levels of calcium and phosphorous in submaxillary and parotid saliva. This can also contribute to an increase in periodontal problems in asthmatics.

Inhaled corticosteroids (ICS) may be absorbed into the systemic circulation, either through the lungs or by the swallowing of drugs that are not inhaled but are deposited at the back of the throat.26 Studies show that ICS can cause a decrease in bone mineral density.26–28 Hanania et al.27 in their study showed that regular use of conventional doses of ICS by patients with asthma can suppress the adrenal function and decrease bone density in a dose-related fashion. Systemic bone loss caused by these drugs, especially when high doses are used for a long time, may have an impact on the onset and progression of periodontal disease.29 Recently, in a study by Han et al.,30 tooth loss in asthma patients undergoing long-term treatment with topically potent ICS was shown to be related to a decrease in bone mineral density, especially in the mandible. Therefore, it is suggested that patients using these types of ICS should have their mandibular bone mineral density checked regularly, especially if they have any risk factors for osteoporosis. In addition, it may be wise for such patients to reduce their ICS dose. The lowest possible dose of ICS to maintain control should be prescribed.26

Asthmatic patients are recommended to adopt more precautionary oral hygiene practices and keep their periodontal health under constant check.

Asthma and oral candidiasis

Oropharyngeal candidiasis is a condition commonly associated with the use of nebulized corticosteroids.31 This side effect may be attributed to the topical effects of these medications on the oral mucosa, as only 10 to 20% of the dose from an inhaler actually reaches the lungs, while the rest remains in the oropharynx. The incidence of oral candidiasis can vary from 1 to 77% with ICS treatment, probably because of the difference in methods used to detect it. This local side effect is mainly seen among patients who use high doses of ICS regularly.32

Generalized immunosuppressive and anti-inflammatory effects of steroids are thought to play a major role in the pathogenesis of candidiasis.33 A study by Fukushima et al.34 suggested that ICS can decrease salivary IgA. This host factor can contribute to the development of oral candidiasis. Knight and Fletcher35 reported that patients who are treated with corticosteroids show a higher level of salivary glucose than the control group. Also, many of the dry powder inhalers contained lactose monohydrate as the carrier vehicle in proportion of 10–25 mg per dose.20 This higher glucose concentration can also promote growth, proliferation and adhesion of Candida to the oral mucosal cells.36 As mentioned earlier, asthmatics who are medicated with beta-2 agonist show a decreased salivary flow rate. This decreased salivary flow rate can be associated with higher oral Candida counts.37

A number of preventive measures can be adopted to minimize oral candidiasis during steroid inhalation.33 Selroos et al.38 reported that the frequency of Candida colonization in patients using dry powder inhalers was diminished by rinsing the mouth after use. Use of a spacer device which can be attached to the inhaler can reduce the local effect of steroids in causing oral candidiasis by minimizing the oropharyngeal deposition of the drug and maximizing the lung deposition.39 Increasing salivary output in subjects with low salivary flow rate can also reduce oral Candida counts. Methods used to increase the salivary flow rate include the use of sialogogue medications, as well as chewing sugar-free gums. Other measures used to reduce colonization by Candida include the use of antimicrobial mouthrinses.40 Controlled administration of topical antimycotics, such as nystatin, is also shown to prevent oral candidasis.41


  1. Top of page
  2. Abstract
  3. Introduction
  4. Conclusions
  5. References

Asthmatic patients may be at a higher risk of developing dental diseases. Dental practitioners should be aware of the correlation between asthma and oral health. They should educate their patients to follow precautionary measures to prevent adverse effects on oral tissues.


  1. Top of page
  2. Abstract
  3. Introduction
  4. Conclusions
  5. References