A Hygienists’ Overview of Halitosis and Taste Alteration

“My breath smells bad.”

“My wife told me to see my dentist to address my bad breath.”

“I can’t taste food as well as before.”

“I can’t taste sweets as much as before.”

My patients have made these comments throughout my years as a dental hygienist. Halitosis and taste alteration remain major concerns for patients who are experiencing them, as well as for clinicians trying to find a solution. Halitosis can also affect people’s social experiences, confidence, and relationships.

Many factors may contribute to halitosis and taste alteration, such as diet, gastrointestinal diseases, acid reflux, digestive complications, medications, xerostomia, systemic health, and oral hygiene. Lack of oral hygiene remains one of the most important factors associated with halitosis and taste alteration.¹

Halitosis

Halitosis is defined as an unpleasant odor that may or may not originate from the oral cavity. Studies have suggested that as much as 50% of the population may suffer from oral malodor, with the majority of cases being due to a lack of oral hygiene.¹ Consequently, periodontal disease, active decay, and tongue biofilm coating may contribute to halitosis. Additionally, other conditions and medications that directly and indirectly affect oral health may lead to halitosis as well.^1-4

The morphology of the dorsal surface of the tongue is ideal for harboring bacteria.^5,6 The large surface area of the tongue, along with papillary structures, favors the accumulation of oral debris. Bacteria metabolize the debris, creating volatile sulfur compounds that contribute to halitosis.⁵ Morita and Wang found a strong positive correlation between patients with heavy tongue coating and halitosis.⁷

Olfaction detects halitosis due to the breakdown of sulfuric and non-sulfuric amino acids in gram-negative anaerobe bacterial plaque and biofilm that are part of the red complex such as P. gingivalis, P. intermedia, F. nucleatum, T. denticola, and V. alcalescens. The presence of these bacteria in high concentrations is a hallmark of periodontal disease.^1,3,4

Moreover, periodontitis is a chronic inflammation of oral tissue that is preceded by untreated gingivitis due to bacterial involvement. The abundance of gram-negative anaerobe bacteria can trigger the inflammatory process, which in turn will cause bleeding on probing (BOP). Often, BOP indicates the presence of biofilm rich in red complex bacteria.⁸

Studies have shown that tongue coating, in addition to oral bacteria count, is significantly associated with a higher incidence of halitosis. Although some studies show a positive relationship between probing depths and halitosis in periodontally involved patients, there are not enough studies to support this hypothesis. As a result, tongue coating still has the strongest correlation.⁵

Taste Alteration

As eating is one of life’s pleasures, taste disturbance can lead to disappointment in enjoying food. Impaired appetite and decreased food intake may result, which could lead to inadequate nutrition. Multiple factors, such as changes in tongue papillae density and papillary alterations, xerostomia, and quality of saliva, affect taste perception.^1,9,10

The four types of tongue papillae include filiform, fungiform, circumvallate, and foliate. Fungiform papillae contain the largest amount of taste buds (approximately 1,600) compared to foliate (several hundred) and circumvallate (approximately 250). In contrast, filiform papillae don’t contain taste buds.¹¹

Aging can lead to alterations of taste buds, which may cause taste impairment. Additionally, with age, the amount of fungiform papillae decreases while there is an increase in filiform papillae. Alterations and changes in papillae density, along with reduced salivary production, often contribute to alterations in taste perception.^1,9

In addition to xerostomia and the alteration of taste buds, the quality of saliva may play a role in taste perception.¹² The parotid gland produces watery serous saliva containing serous acini, while the submandibular and sublingual glands are known as mixed glands because they produce both mucous and serous acini.¹³ During mastication, the parotid gland produces up to 60% of saliva.¹² Additionally, parotid and submandibular glands produce amylase, which helps with starch digestion.¹⁴ In short, a person with xerostomia may have difficulties tasting sweets.

Moreover, Solamdal et al. explained that older adults with an excess amount of lactobacilli have sour taste alteration. They hypothesize that since this bacterium produces acid, the sour taste buds may adapt to the new environment, which may increase the sour taste threshold.¹⁰

Additionally, xerostomia and excess plaque biofilm due to poor oral hygiene are associated with a decreased ability to taste salt.¹⁰

Besides xerostomia, saliva quality, and oral bacteria, some studies suggested removable appliances and tongue coating may affect taste perception. However, none of the studies were able to prove this hypothesis. In contrast, some studies found no differences between patients with heavy tongue coating and/or removable appliances compared to those without.^1,10

In Closing

Halitosis can arise for multiple reasons, such as an underlying systemic condition, medication side effects, and, most often, poor oral health. Xerostomia, active decay, heavy tongue coating, and poor oral hygiene are among the main reasons. Often, addressing these issues will resolve halitosis.^1-4

Aging can lead to papillary alterations and changes in papillae density, which may contribute to taste alteration.^1,9 Sweet taste alteration can be due to a decreased level of amylase protein, which may occur due to xerostomia. An increased level of lactobacilli can reduce sour taste perception, and poor oral hygiene and xerostomia can affect salt taste perception.^10,14 However, taste alteration remains a mystery due to a lack of research and the subjectivity of this concept. Therefore, further studies must be done.

Although there is no positive correlation between halitosis and taste alteration, it is suggested that good oral hygiene and regular oral care may help with these concerns.¹⁰

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References

1. Nalcaci, R., Baran, I. Factors Associated With Self-Reported Halitosis (SRH) and Perceived Taste Disturbance (PTD) in Elderly. Archives of Gerontology and Geriatrics. 2008; 46(3): 307-316. https://www.sciencedirect.com/science/article/abs/pii/S0167494307001288
2. Cherney, K. Can Bad Breath Be a Sign That You Have a Cavity? (2023, May 5). Healthline. https://www.healthline.com/health/dental-and-oral-health/do-cavities-cause-bad-breath
3. Cassiano, L.S., Leite, F.R M., López, R., et al. The Association Between Halitosis and Chemosensory Disorders: A Systematic Review. Oral Diseases. 2023; 29(2): 369-375. https://doi.org/10.1111/odi.13823
4. Lee, Y.H., Shin, S.I. Hong, J.Y. Investigation of Volatile Sulfur Compound Level and Halitosis in Patients with Gingivitis and Periodontitis. Scientific Reports. 2023; 13(1): 13175. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10425441/
5. Amou, T., Hinode, D., Yoshioka, M., Grenier, D. Relationship Between Halitosis and Periodontal Disease – Associated Oral Bacteria in Tongue Coatings. International Journal of Dental Hygiene. 2014; 12(2): 145-151. https://pubmed.ncbi.nlm.nih.gov/23890391/
6. Roldán, S., Herrera, D., Sanz, M. Biofilms and the Tongue: Therapeutical Approaches for the Control of Halitosis. Clinical Oral Investigations. 2003; 7(4): 189-197. https://pubmed.ncbi.nlm.nih.gov/14513303/
7. Morita, M., Wang, H.L. Relationship Between Sulcular Sulfide Level and Oral Malodor in Subjects With Periodontal Disease. Journal of Periodontology. 2001; 72(1): 79-84. https://doi.org/10.1902/jop.2001.72.1.79
8. Carvalho, A.P., Moura, M.F., Costa, F.O., Cota, L.O. Correlations Between Different Plaque Indexes and Bleeding on Probing: A Concurrent Validity Study. Journal of Clinical and Experimental Dentistry. 2023; 15(1): e9-e16. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9899362/
9. Alia, S., Aquilanti, L., Pugnaloni, S., et al. The Influence of Age and Oral Health on Taste Perception in Older Adults: A Case-Control Study. Nutrients. 2021; 13(11): 4166. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8618294/
10. Solemdal, K., Sandvik, L., Willumsen, T., et al. The Impact of Oral Health on Taste Ability in Acutely Hospitalized Elderly. PloS One. 2012; 7(5): e36557. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3343000/
11. Tongue. (2022, April 25). Cleveland Clinic. https://my.clevelandclinic.org/health/body/22845-tongue
12. Muñoz-González, C., Feron, G., Canon, F. Main Effects of Human Saliva on Flavour Perception and the Potential Contribution to Food Consumption. Proceedings of the Nutrition Society. 2018; 77(4): 423-431. doi:10.1017/S0029665118000113
13. Ghannam, M.G., Singh, P. (2023, May 29). Anatomy, Head and Neck, Salivary Glands. StatPearls. https://www.ncbi.nlm.nih.gov/books/NBK538325/
14. Martin, L.E., Gutierrez, V.A., Torregrossa, A.M. The Role of Saliva in Taste and Food Intake. Physiology and Behavior. 2023; 262: 114109. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10246345/