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May 12, 2008

By Jane M. Chalmers, BDSc, MS, PhD, DABSCD

A variety of terms are used and confused when describing the problems that our patients have with "dry mouth." The term xerostomia is a person's subjective self-perception of having a dry mouth.(1) However, xerostomia is also often incorrectly and globally used to describe a reduction in salivary flow. When a person has a change in the quality and/or quantity of saliva, he or she has salivary dysfunction or salivary gland hypofunction (SGH), in which the minor and/or major salivary glands are affected.(1,2) Thus, xerostomia can only be assessed by directly questioning patients, while SGH can be determined by using clinical assessment of secretions, viscosity, and pH, and using sialometry (collecting unstimulated and stimulated saliva).(3,4) When salivary flow rate drops below a designated clinical threshold, it is categorized as SGH.(5)

To further complicate our understanding of dry mouth, epidemiological studies have evidenced that not all patients with xerostomia have SGH and not all patients with SGH have xerostomia.(5) Thomson, in a review of geriatric oral epidemiological studies of noninstitutionalized older adults, estimated that xerostomia prevalence was approximately 21% and SGH prevalence was slightly higher than this in the range of 22% to 40%.(5) However, it has been reported that as low as 5.7% of study cohorts of such older adults had both xerostomia and SGH.(6)

Assessment of xerostomia can be easily conducted before or at the dental appointment by the use of a short questionnaire. Several questionnaires exist that can be used, including the four questions used by Fox et al. (1987); the Xerostomia Inventory (1999) (Table 1); or a seven-item group of questions used by Locker et al. (2003).(1-3,5,7)

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Assessment of SGH can be broken down into two main steps: 1. a clinical screening step for all patients, and 2. more comprehensive testing using kits (e.g., GC Saliva Check or Vivadent CRT Buffer) for patients with a probable higher risk of salivary dysfunction. A clinical visual screening assessment of all patients is useful to review:

• Salivary consistency (watery, bubbly, frothy, ropey)
• Salivary pooling
• Minor salivary gland function(4)
* Sit the patient upright
* Roll out the lower lip and dry with a gauze square
* Measure the time taken for droplets of saliva to appear at the orifices of the minor gland ducts
* Apply a single ply of tissue to make it easier to see the droplets of saliva

The testing kits provide a simple and efficient way to further assess the pH of unstimulated and stimulated saliva, and the buffering capacity of the saliva to neutralize acid. Mean whole-saliva flow rates reported are 0.3ml/min for unstimulated saliva and 1.7ml/min for stimulated saliva.(5) A flow rate of less than 0.1ml/min for unstimulated saliva and 0.7ml/min for stimulated saliva is considered pathologic for SGH.(4) This is a clinical task that a dental auxiliary can easily perform, especially with systems such as the GC Saliva Check kit, which comes with a user-friendly mat to facilitate the steps in the testing process. Thus, a review of the xerostomia and SGH results can help to reveal when saliva dysfunction is present, how the patient perceives that it affects his/her life, and what are the best ways to treat it.

Medications, polypharmacy, and dry mouth are complex issues. Many medications have side effects that include xerostomia and SGH. In some references and literature, hundreds of drugs are included in lists of xerostomic medications. However, it is important to note that not all of these referenced drug classes have established oral adverse effects of xerostomia and/or SGH. Those drug classes which do include: anticholinergics, antidepressants, antiparkinsonian agents, systemic antihistamines, antihypertensives, antiemetics, antipsychotics, and narcotics. Be aware that not all drugs within a class will have the same level of anticholinergic adverse effects. For example, if antipsychotics are reviewed, haloperidol will have the most severe tardive dyskinetic and extrapyramidal adverse effects, but lower anticholinergic adverse effects in comparison to thioridazine, for which the reverse is true.(8) Thus, further research is being conducted to investigate which drugs within a class have the worst anticholinergic oral adverse effects and how these are related to oral disease experience, incidence, and tooth loss.(6,9)

Several approaches can be clinically used to treat xerostomia and SGH. Hydration is often recommended as is appropriate given a patient's other medical conditions that may limit water intake. Water can be sipped or sprayed into the mouth or ice chips can be sucked. Limiting smoking and alcohol consumption is helpful, as is avoiding alcohol-containing or sodium lauryl sulphate-containing dental products. Saliva substitutes are buffering, rehydrating, or mucosal protective products to help replace the functions and feeling of the missing saliva.(4) A range of substitutes is available as gels, liquids, and sprays from a variety of distributors.(10) The Laclede Oral Balance products have wide international clinical acceptance from dental professionals and patients, and include a gel and liquid which contain bioactive enzymes with essential amino acids.(11,12) These substitutes can be gently rubbed all over the oral soft tissues and teeth. Applying substitutes on the internal and external surfaces of dentures will also improve denture retention in those patients with little or no saliva (e.g., Biotene Oral Balance or Denture Grip; GC Dry Mouth Gel). A bicarbonate mouth rinse can also be helpful to neutralize acids in thick dental plaque and make the mouth feel more comfortable: mix ½ tsp baking soda with 1 cup warm water; rinse gently for 30 seconds several times per day.(4) Saliva stimulants are either nonprescription or prescription. Over-the-counter gums and candies are well-accepted by many patients — ensure they are sugar-free and if possible contain xylitol (e.g., Biotene gum, Trident White with Recaldent gum, Spry gum, Theragum, Theramints). Another product to stimulate saliva is the SalivaSure tablet which contains fruit acids and a phosphate buffer; a tablet is placed at one of the major salivary gland duct openings (parotid or submandibular) and sucked until dissolved.(13) While a variety of prescription-only cholinergic medications can increase salivary flow (pilocarpine and cevimeline), all have significant side effects (particularly on the cardiovascular system) and it is advisable to consult a patient's medical practitioner before prescribing such medications.

Drinking milk has also been advocated to improve oral comfort for patients with oral mucositis, xerostomia, and/or SGH. Although the casein-based Recaldent products (Trident White with Recaldent gum (~1%) and GC MI Paste/MI Paste Plus (10%)) were developed for the prevention of dental hard tissue demineralization and the promotion of remineralization, clinical case reports and studies are evidencing the use and satisfaction of these and similar products by patients with xerostomia and SGH.(14,15) Recaldent products increase the mineralizing properties of saliva by using casein phosphopeptides to stabilize amorphous calcium phosphate, and GC MI Paste Plus contains ~20% glycerin, which may also contribute to the improvement of oral comfort.(16,17) For patients with severe salivary dysfunction, it is recommended to rinse the mouth with a little water before applying MI Paste Plus. This product is particularly helpful to provide oral comfort when the mouth is dry due to the use of medications postsurgery, during chemotherapy/head and neck radiation treatment, or for women with severe nausea and vomiting during pregnancy.(4)

Saliva is also key to maintaining the environment of the mucosal taste receptor cells, with water the most important salivary component.(18) Any changes in the quantity and/or quality of saliva will therefore affect taste sensitivity and the adaption of taste receptors to saliva.(18) If salivary dysfunction is present, there will be an elevated taste threshold, but normal perception of supra-threshold intensities for sweet, salty, sour, and bitter.(19) That is, such people will have poorer taste detection, and some loss of taste sensitivity, but this may not be a severe loss. This is true especially if major and minor salivary glands are affected but damage to the taste function of the posterior part of the tongue is minimal, including the minor von Ebner's glands draining into the papillae.(18) Changes in the concentration of major salivary ions will affect taste — salty taste is only detected when it is above salivary sodium chloride concentrations, and sour taste is buffered by salivary bicarbonate.(20) Interestingly, taste changes are also related to the renewal time of taste receptor cells (~10 days). Recovery of any changed taste sensitivity is time-dependent and related to salivary water, which can be modulated by the use of saliva substitutes and water.(18) Concurrent use of saliva substitutes is recommended to improve taste. Thus, highly concentrated acidic and alcoholic products may not be well-tolerated by patients with saliva dysfunction, and the development of preference for sweet foods is common. This may be the case not only for people with atrophic and pathological oral mucosa, but also for those with apparently normal oral mucosa (such as in burning mouth syndrome, which has recently been linked to salivary compositional alterations).(21)

Case studies

Mrs. KP is a 52-year-old woman with Sjogren's syndrome, hypertension, and osteoarthritis. Completion of the XI assessment revealed that she had problems with dry mouth, dry skin, and dry eyes throughout the day, which worsened at night and with eating. Testing of her saliva revealed that she had salivary gland hypofunction (SGH) with lowered unstimulated and stimulated flow rates (4.0mL/5minutes), and reduced buffering capacity (range 6-9). Mrs. KP had used water, xylitol gum and candy, and several types of saliva substitutes previously to try to improve her dry mouth problems. MI Paste Plus was recommended for Mrs. KP preventively for caries and dry mouth relief; a pea-size amount was prescribed to be gently rubbed onto her teeth and oral soft tissues two to three times daily (Figures 1 to 3). She tried several flavors and preferred the Vanilla MI Paste Plus. Mrs. KP reported a dramatic improvement in her dry mouth problems after using the MI Paste Plus, especially before meals and sleeping, and reported that the improvement in dry mouth lasted for several hours with each MI Paste Plus application.

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Figures 1 to 3 — Mrs. KP ...

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Mr. SD is a 71-year-old man with chronic graft-vs.-host disease, a complication of allogenic bone marrow transplantation, which has resulted in severe xerostomia and SGH. He had an ongoing struggle with recurrent dental decay around his restorations and crowns (Figures 4 to 7). Completion of the Xerostomia Inventory revealed that he had a severe dry mouth that was worse during the day, and he had problems eating and swallowing many foods. He had recurrent intraoral candidal infections in several locations. His oral mucosa was very thin and friable. Testing of his saliva revealed very severe salivary gland hypofunction with low unstimulated and stimulated flow rates (although some saliva was still being produced when stimulated = 1.5mL/5 minutes) and a reduced buffering capacity (range 0 to 5). His saliva was very thin and sparse. Mr. SD had ongoing rampant, recurrent coronal and root caries, and the use of a variety of antimicrobial and fluoride products as well as saliva substitutes were trialed by him. Recurrent caries were occurring within a four-week period in recent years. Due to his severe dry mouth, Mr. SD found compliance with various preventive products challenging. Although he had never been a gum chewer, Mr. SD was surprised to find the most relief for his dry mouth problems from chewing of Trident White with Recaldent four to five times daily for several minutes. Thus, in addition to dramatically reducing his rate of recurrent caries within an eight-week period, this Recaldent gum improved Mr. SD's comfort with eating and also with sleeping.

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Figures 4 to 7 — Mr. SD ...

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Jane Margaret Chalmers, BDSc, MS, PhD, DABSCD, is a tenured associate professor in the Department of Preventive and Community Dentistry at the University of Iowa College of Dentistry and also has an appointment in the College of Nursing. She is the co-director of the Interdisciplinary Geriatric Fellowship and the Junior Geriatric Dentistry Course. Dr. Chalmers also teaches and provides clinical patient care in the Geriatric and Special Needs Program. She completed a Bachelor of Dental Science Degree at The University of Melbourne, Australia, in 1987, a Master of Science (dental public health — geriatrics) at The University of Iowa in 1995, and a PhD in oral epidemiology at The University of Adelaide, Australia, in 2001. She is a registered specialist in dental public health in Australia, and in 2004 was one of the first Australian specialists registered in special needs dentistry. She is a Diplomate of the American Board of Special Care Dentistry. She has published more than 45 refereed journal articles on geriatric and special needs dentistry and minimal intervention dentistry, as well as multiple reports and oral health promotion materials in these fields. She is an associate editor for the Special Care in Dentistry journal and editorial board member for Gerodontology. She is president of the IADR Geriatric Oral Research Group. She is actively involved in the teaching of special needs dentistry in the United States and in Australasia for undergraduate and postgraduate dental, dental hygiene, dental auxiliary, and allied health students. She is an active researcher in the field of geriatric dentistry, in particular the study of the oral health of older adults with dementia, and has received many awards for her research. You may contact Dr. Chalmers at jane-chalmers@uiowa.edu.

References

1. Thomson WM, Chalmers JM, Spencer AH, Williams SM. The Xerostomia Inventory: a multi-item approach to measuring dry mouth. Community Dental Health 1999; 16:12-17.

2. Thomson WM, Williams SM. Further testing of the Xerostomia Inventory. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2000; 89:46-50.

3. Fox PC, Busch KA, Baum BJ. Subjective reports of xerostomia and objective measurements of salivary gland performance. Journal American Dental Association 1987; 115:581-584.

4. Walsh LJ. Chapter 7 — Lifestyle Impacts on Oral Health. In: Preservation and Restoration of Tooth Structure. Mount GJ and Hume WR. Knowledge Books and Software. 2005.

5. Thomson WM. Issues in the epidemiological investigation of dry mouth. Gerodontology 2005; 22:65-76.

6. Thomson WM, Chalmers JM. The South Australian Dental Longitudinal Study Five-year Follow-up. AIHW Dental Statistics and Research Unit Research Report No. 3. 2002. AIHW Catalogue No. DEN 102.

7. Locker D. Dental status, xerostomia and the oral health-related quality of life of an elderly institutionalized population. Spec Care Dent 2003; 23:86-93.

8. Australian Medicines Handbook. AMH Pty Ltd. Adelaide, Australia. 2000.

9. Diaz-Arnold AM, Marek CA. The impact of saliva on patient care: A literature review. J Pros Dent 2002; 88:337-43.

10. Chalmers JM, Pearson A. Oral hygiene care for residents with dementia: a literature review. Accepted J Adv Nursing December 2004. In press September 2005.

11. Shahdad SA, Taylor C, Barclay SC, Steen IN, Preshaw PM. A double-blind, crossover study of Biotene Oral Balance and BioXtra systems as salivary substitutes in patients with post-radiotherapy xerostomia. European J of Cancer Care 2005; 14:319-326.

12. Epstein JB, Emerton S, Le ND, Stevenson-Moore P. A double-blind crossover trial of Oral Balance gel and Biotene toothpaste versus placebo in patents with xerostomia following radiation therapy. Oral Oncology 1999; 35:132-137.

13. Pugliese MD and Associates. Clinical Study on SalivaSure Lozenges. PA, 2004.

14. Hay KD, Morton RP. The efficacy of casein phosphoprotein-calcium phosphate complex (DC-CP) [DentacalRTM] as a mouth moistener in patients with severe xerostomia. New Zealand Dental Journal 2003; 99:46-48.

15. Hay KD, Thomson WM. A clinical trial of the anticaries efficacy of casein derivatives complexed with calcium phosphate. Oral Surg, Oral Med, Oral Pathol, Oral Radiol and Endo 2002; 93:271-275.

16. Reynolds EC and Walsh LJ. Additional aids to the remineralization of tooth structure. In: Preservation and Restoration of Tooth Structure. Mount GJ and Hume WR. Knowledge Books and Software. 2005.

17. Reynolds EC, Cai F, Shen P, Walker GD. Retention in plaque and remineralization of enamel lesions by various forms of calcium in a mouth rinse or sugar-free chewing gum. J Dent Res. 2003 Mar; 82(3):206-11.

18. Matsuo R. Role of saliva in the maintenance of taste sensitivity. Crit Rev Oral Biol Med 2000; 11(2):216-219.

19. Weiffenbach JM, Schwartz LK, Atkinson JC, Fox PC. Taste performance in Sjogren's syndrome. Physiol Behav 1995; 57:89-96.

20. Ship JA. The influence of aging on oral health and consequences for taste and smell. Physiol Behav 1999; 66(2):209-215.

21. Nagler RM, Herschkovich O. Sialochemical and gustatory analysis in patients with oral sensory complaints. J of Pain. 2004; 5(1):56-63.

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