|Year : 2020 | Volume
| Issue : 1 | Page : 47-53
Association between oral health status and salivary flow rate among individuals with and without burning mouth: A case control study
KS Sruthi, R Yashoda, Manjunath P Puranik
Department of Public Health Dentistry, Government Dental College and Research Institute, Bengaluru, Karnataka, India
|Date of Submission||27-Dec-2019|
|Date of Decision||03-Feb-2020|
|Date of Acceptance||27-Jan-2020|
|Date of Web Publication||2-Mar-2020|
Dr. K S Sruthi
Department of Public Health Dentistry, Government Dental College and Research Institute, Bengaluru, Karnataka
Source of Support: None, Conflict of Interest: None
Background: Individuals with burning mouth suffer from a variety of difficulties in their day-to-day life. Studies related to the role of saliva in burning mouth complaining individuals and their effect on oral health conditions are scarce. Aim: The aim of the study was to determine an association of the salivary flow rate and oral health among individuals with and without burning mouth. Materials and Methods: A case–control study was conducted among 200 individuals aged 18–75 years with and without burning mouth in Bangalore city. Demographic profile, medical, dental and personal history were recorded. Unstimulated and stimulated salivary flow rate and oral health status were assessed. Chi-square test, unpaired t-test, Spearman's correlation, and binary logistic regression were applied.P < 0.05 was considered statistically significant. Results: Majority of individuals who complained of burning mouth were females aged 45–64 years. The most common systemic condition and lesion were anemia and oral submucous fibrosis. A statistically significant very weak negative correlation was present between unstimulated and stimulated salivary flow rate and Decayed, Missing and Filled teeth. Individuals with reduced salivary flow rate had 3–5 times higher odds of having burning mouth (P < 0.001). Conclusions: There is an association between salivary flow and caries experience among individuals with a burning mouth. Hence, proper diagnosis and appropriate management of these individuals must be done to reduce the difficulties faced by them.
Keywords: Burning mouth, case–control study, dental caries, oral health, salivary flow
|How to cite this article:|
Sruthi K S, Yashoda R, Puranik MP. Association between oral health status and salivary flow rate among individuals with and without burning mouth: A case control study. J Indian Assoc Public Health Dent 2020;18:47-53
|How to cite this URL:|
Sruthi K S, Yashoda R, Puranik MP. Association between oral health status and salivary flow rate among individuals with and without burning mouth: A case control study. J Indian Assoc Public Health Dent [serial online] 2020 [cited 2021 May 7];18:47-53. Available from: https://www.jiaphd.org/text.asp?2020/18/1/47/279814
| Introduction|| |
Oral health is an integral part of ones' well-being which reflects their general health and disease. Saliva plays an important role in maintaining oral health and functions. Patients with reduced salivary flow may complain of subjective oral dryness, suffer from eating problems, and have difficulties with speech and swallowing. Pharmacologic agents can mimic or antagonize various regulatory aspects of salivation, thus affecting both salivary flow rate and composition. Reduced salivary flow and increased subjective oral dryness can have an impact on some diseases and their treatment.
Dry mouth is associated with burning mouth which is usually accompanied by multiple drug use, taste alterations, and possible concomitant anxiety and depression. The frequent presence of associated symptoms and the clinical complexity characterizing burning mouth have led some authors to prefer the term “burning mouth syndrome“ (BMS) in reference to a clinical picture, in which no apparent oral mucosal lesions are found. Practically, all patients with burning mouths that is not attributable to known causes present with associated factors which may be considered to favor perceptive alterations of the oral mucosa.
Burning-mouth sensation is a disorder in which the patient experiences constant intraoral pain of mucosal origin. The prevalence of this condition varies from 5.1% to 17.9% and is especially seen among middle-aged women. The burning sensation may become unbearable for the patient. This condition gets even worsened if it is accompanied by the pain. In some cases, the problem can be attributed to concrete and more or less identifiable alterations (geographic tongue, oral lichen planus, candidiasis, ulcerations, etc.), though in other cases, no apparent cause exists. In these latter situations, the main feature is a burning sensation in the oral cavity, with a clinically normal oral mucosa. The tongue is most frequently affected, which is also known as glossodynia or glossopyrosis. The disorder is, in turn, associated with different local, systemic, and psychological factors, though the underlying cause is not clear. Various local factors capable of altering oral mucosal perception include tobacco smoking, habitual ingestion of very hot foods, spicy food, and parafunctional habits. Hyposalivation is also noted as an etiology among individuals with burning mouths. Reduced salivary flow can affect oral health functions. Decreased saliva secretion increases the risk of dental caries.
Oral health status among individuals with burning mouth remains unclear. However, based on the etiology of the condition, dental health might also be affected in the individuals with burning mouth, especially among those with a reduced salivary flow. There is a lack of literature about the etiologic role of saliva in a burning mouth and its associated factors. Hence, a study was conducted to determine the association between saliva and oral health in individuals with and without burning mouth.
| Materials and Methods|| |
A case–control study was conducted to determine the association between salivary flow rate and burning mouth sensation among individuals with and without burning mouth in Bangalore city from June to October 2018. A protocol of the intended study was submitted to the Institutional Ethical Committee and Review Board, and ethical clearance was obtained. The study was conducted in accordance with the Helsinki Declaration of 1975, as revised in 2000.
Permission was obtained from the directors of the hospitals after explaining the purpose and procedure of the study. The study participants were informed about the study, the method of saliva collection, and the oral examination and were assured that their participation is purely voluntary and confidentiality will be maintained. The written informed consent was obtained from the participants. The principal investigator was trained and calibrated in the department of public health dentistry. The kappa coefficient value (k) for intraexaminer reliability was 0.80–0.90, reflecting a high degree of conformity in observation.
G*Power software 22.214.171.124 (Heinrich- Heine- Universität, Dusseldorf, Germany) was used to calculate the sample size with a statistical power of 90% at alpha value 0.05 and effect size 0.50. The sample size calculated was 86, which was rounded off to 100 for each group. Patients visiting various government hospitals with and without burning mouth sensation were included in the study based on the eligibility criteria. Individuals aged 18–75 years complaining of burning mouth sensation were included in the study. Individuals with a previous history of head-and-neck malignancy and history of radiation therapy in the head-and-neck area and who had undergone surgery that reduces the salivary flow were excluded from the study. Age- and gender-matched controls without burning sensation were selected. The burning mouth was confirmed through records.
Data were collected from the study participants during hospital working hours by a blinded investigator. General demographic details, medical history, menopausal history, burning mouth sensation history, dental history, personal habits, hemoglobin (Hb), and random blood sugar (RBS) from the investigation reports were recorded. Clinical examination included assessment of dental caries and periodontal status and were recorded using the WHO 2013 proforma. Participants were seated on a comfortable chair and Type 3 dental examination was performed by a single calibrated investigator under artificial light using autoclaved instruments.
Unstimulated saliva was collected after a minimum of 30 min at rest during which the participants were asked not to eat, drink, or chew gum. Participants were instructed to expectorate into a graduated tube for 5 min in a quiet room at rest without swallowing and any stimulation. After the collection of unstimulated saliva, patients were instructed to chew paraffin wax and to expectorate into another graduated tube for another 5 min without swallowing while chewing on the paraffin wax.
The data collected were entered into MS excel spreadsheet. Data were analyzed using the Statistical Package for the Social Sciences version 20 (SPSS 20.0 IBM, Armonk, NY, USA). Socioeconomic status was assessed using the Kuppuswamy scale. Income was updated using All-India Average Consumer Price Index for Industrial Workers (CPI-IW = 274) for August 2018., Normal unstimulated salivary flow was considered as 0.25–0.35 ml/min and for stimulated was about 1–3 ml/min. Unstimulated salivary flow rate ≤0.25 ml/min and stimulated salivary flow rate ≤1 ml/min were considered as reduced salivation. Hb levels 12–15.1 g/dl (women) and 13.8–17.2 g/dl (men) were considered normal. Any value less than the lower limit was considered as a reduced Hb level. RBS level >200 mg/dl was considered a high blood sugar level. Descriptive and inferential statistical analyses were done. Chi-square/Fisher's exact test was used to find the difference between proportions. Unpaired t-test was used to find a difference in mean scores between continuous variables. Spearman's correlation was used to find correlation among salivary flow and dental caries, gingivitis, and periodontitis in burning mouth group and control group. Binary logistic regression was applied using burning mouth as the dependent variable.A P value < 0.05 was considered statistically significant.
| Results|| |
This study included 100 patients with burning mouth and 100 age- and gender-matched controls [Table 1]. A majority of individuals who complained of burning mouth were females between the age group of 45–64 years, belonged to the upper lower and lower middle class. Anemia and oral submucous fibrosis (OSMF) were the most common systemic problems and oral lesions among the individuals [Figure 1] and [Figure 2]. The frequency of BMS was 3%, of which 2% were females. A majority of individuals were under medication for various systemic conditions [Figure 3]. Investigation reports revealed a statistically significant higher mean RBS level (cases: 139.56 ± 57.77 mg/dL and controls: 113.45 ± 23.69 mg/dL [P < 0.001]) and decreased Hb level (cases: 11.10 ± 3.21 g/dL and controls: 13.49 ± 2.12 g/dL [P < 0.001]) among those with burning mouths than those without burning mouths.
|Table 1: Distribution of the study groups according to the age and gender|
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|Figure 3: Distribution of the study groups based on the medication history|
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Major proportion of the cases reported burning mouth in the buccal mucosa, bilateral involvement and duration of <3 years. Majority described the nature of burning mouth as intermittent and intensity as mild to moderate [Table 2]. Perception of dry mouth and altered taste was present in a higher proportion among cases. The majority of females with burning mouths had attained menopause. Among women who have attained menopause, a significantly higher proportion of females with reduced unstimulated (50.0%) and stimulated salivary flow (53.8%) (P < 0.001) was found among cases when compared to controls (26.7% – both unstimulated and stimulated salivary flow).
|Table 2: Distribution of burning mouth characteristics among cases (n=100)|
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Smokeless tobacco usage was found to be higher among individuals with burning mouth when compared to controls. More number of cases (22%) had bruxism compared to controls (9%), and the association between bruxism and burning mouth was statistically significant (P = 0.01). Reduced level of both unstimulated and stimulated salivary flow rate was noted among the individuals with burning mouths compared to those without burning mouths [Table 3].
|Table 3: Mean salivary flow rate, caries experience, and periodontal disease among the study groups|
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Considering the oral health status, a significantly higher proportion of individuals with burning mouth had caries experience, while gingivitis and periodontitis were similar between the groups [Table 3]. A very weak negative correlation was present between both stimulated and unstimulated salivary flow rates and with dental caries [Table 4]. No statistically significant difference was found between the groups for the mean number of teeth affected with gingivitis, whereas a significantly increased number of teeth among cases were found to have a pocket depth of 4–5 mm.
|Table 4: Correlation of oral health status and salivary flow rate and among the study groups|
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Females had higher odds of having burning mouths compared to males. Individuals aged more than 45 years had 1.77 times the chance of having burnings mouth compared to those of <45 years of age. Odds of having reduced salivary flow rate among individuals with burning mouth were 3–5 times more than that among individuals without burning mouths. Odds of having burning mouth for individuals with reduced Hb level were 4.14 [Table 5].
|Table 5: Logistic regression analysis with burning mouth as dependent variable|
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| Discussion|| |
Burning mouth is a very enigmatic pathology of various etiopathogeneses that is characterized by the presence of a chronic burning sensation in the oral mucosa. Proper diagnosis and management of the condition is utmost important.
Age changes such as thinning of stratified squamous epithelium, loss of elasticity, atrophies, a decline in immunological responsiveness, an increased incidence of oral and systemic disorders, along with increased use of medications might contribute to the occurrence of burning mouth. A majority of participants in the present study were between the age group of 45–64 years. Burning mouth was 1.77 times more likely among individuals who were aged above 45 years in the present study compared to the control group. This is in line with earlier studies.,,,,,
Womanhood experience an upsurge in oral symptoms that may result from endocrine disturbances (reduced estrogen), calcium and vitamin deficiency, and several psychological issues. This is sometimes reflected in the oral cavity as burning sensation, whereas among males, tobacco, alcohol habits, stress, and systemic problems might be the contributory factor for the burning mouth. Female-to-male ratio in the present study was 4.1:1, which is similar to the study by Torgerson Females in the present study were 1.81 times more likely to report with burning mouth compared to males. A similar association of female gender and burning mouth was found in a study by das Neves de Araújo Lima et al.
The present study could not find any association between social class and burning mouth probably due to the fact that cases and controls were recruited from the same hospitals in a given geographic area.
Atrophic changes of the tongue, atrophy, and reduction of the epithelial thickness of the buccal epithelium would suggest generalized atrophy of the whole epithelium in iron deficiency anemia, resulting in the burning symptoms among these individuals. Diabetes causes changes in the salivary gland that causes a decrease in the salivary flow, thereby resulting in dryness of the mucosa. Various cases of drug-associated burning mouth have been reported. Angiotensin converting enzyme inhibitors and angiotensin receptor blockers are perhaps the most commonly reported drugs. This may be the product of an inflammatory reaction generated by an increase in bradykinin. Kallikrein, a molecule active in the kinin pathway, may be increased in the saliva of BMS patients, resulting in increased inflammation. A higher proportion of individuals with burning mouths were using medication in a study by Acharya et al., which was in line with the present study.
In the present study, the majority of the individuals with burning mouth had either anemia, diabetes, or hypertension. Earlier studies have reported comorbities such as anemia, diabetes, or hypertension. Increased RBS and reduced Hb have been reported in the present study among the burning mouth individuals compared to controls, which is indicative of the link between medical conditions and burning mouth.
In the present study, OSMF, leukoplakia, and lichen planus are the common oral conditions reported in the individuals with burning mouths. Burning sensation was reported among individuals with OSMF, lichen planus, and candidiasis in previous literatures.,,
Burning sensation is a frequent complaint of individuals with candidiasis. Furthermore, there is an increase in the fungal infection as fungus thrives on the high glucose levels in the saliva. These together suggest for the burning sensation in diabetic individuals. The most common initial symptoms and signs for OSMF are a burning sensation, dry mouth, blanching oral mucosa, and ulceration. Repeated irritation and the tobacco exposure might result in the oral mucosal changes which might be the contributory factor for burning sensation among leukoplakia.
The relationship with menopause is due to the dramatic fall in gonadal steroids that occurs at that time and further alters the production of neuroactive steroids. Dysregulation of hormones leads to an altered production of neuroactive steroids in the skin, mucosa, and the nervous system. However, the exact etiopathogenesis still remains largely obscure. The prevalence of burning mouth is about 18%–33% in postmenopausal women. A previous study has reported BMS in nearly 21% of postmenopausal women. This study found a higher prevalence than the previous study (38%). Menopause is an age-related condition which, in turn, is associated with burning mouths. Since the cases and controls were age and gender matched, a statistically significant association could not be found in the present study.
Unstimulated salivary flow rate was significantly reduced among 50% (n = 13) women who had attained menopause in cases as compared to 26% (n = 4) in controls in this study. This is in line with a study by Mojabi et al. where 50% of women who attained menopause had dry mouths. However, a study by das Neves de Araújo Lima et al. could not establish a significant association.
The high prevalence of oral parafunctional habits in individuals with BMS suggests the presence of inflammation at the subclinical level due to repetitive microtrauma that might cause burning sensations. These parafunctional habits might have resulted in neuropathic changes that have ultimately lead to burning mouth. Parafunctional habits were reported by 22% in the present study, which was higher when compared to 3% of individuals in a study by Brailo et al. Other habits such as mouth breathing were found to be similar among the groups. In the present study, bruxism was found to be significantly higher among cases with the odds ratio of 3.91. Hakeberg et al. could not find any significant association between bruxism and burning mouth.
Reduced salivary flow is associated with various changes in both hard and soft tissues in the oral cavity. An alteration of the concentration of the organic and inorganic salivary components, determined by the type of secretion or by the amount of saliva secreted, might possibly influence stimulus capture and reception and alter oral mucosal perception in patients with BMS. These changes are being reflected as an increased prevalence of dental caries among individuals with the reduced salivary flow. Individuals suffering from burning mouth who have a reduced salivary flow might also show some of these changes. A statistically significant difference in the number of individuals among the cases was identified with reduced unstimulated and stimulated salivary flow which was similar to a study by Spadari et al. where a statistically significant difference was identified among the groups with unstimulated salivary flow rate.
In this study, participants with reduced unstimulated and stimulated salivary flow were 4-folds more likely to experience and report burning mouth compared to participants with normal flow rates.
Odds of having caries experience among individuals with burning mouths were 2.306 in the present study. The mean number of teeth with caries experience and filled teeth among burning mouth individuals was higher compared to that of the control group. However, the relationship between caries experience and burning mouth was not assessed in the previous studies. Cases were found to have reduced salivary flow and also high caries experience which could be attributed to salivary flow rather than the burning mouth. Reduced salivary flow can cause burning mouth which, in turn, acts as a risk factor for dental caries. Hence, an indirect association could be identified between the prevalence of burning mouth and dental caries.
An association between gingivitis and burning mouth could not be proven in the present study. Although a negative correlation could be identified between gingivitis and salivary flow rate, this was not found to be significant. Gingivitis was a common complaint among individuals with burning mouths in a study by Bergdahl et al. in Sweden. The lack of proper oral hygiene practices due to oral irritation among individuals with burning mouth might be the contributory factor for gingivitis in this group. As periodontal disease is related to age and social class, and also uniform distribution across the age and class was present in the study, the difference in periodontal status remained nonsignificant.
Hence, females aged 45 years and above, reduced Hb level, increased RBS level, bruxism, and reduced salivary flow were more likely to report with burning mouths. Salivary flow affects caries experience; hence, individuals with reduced salivary flow concomitantly report with caries and burning mouth.
To the best of our knowledge, this is the first study to assess socioeconomic status, oral health status, and salivary flow rate among individuals with burning mouths with a case–control study design. This study demonstrates the importance of saliva in maintaining oral health, as salivary flow mediated the occurrence of burning mouth.
Case–control study design allowed the assessment of exposure through history and records with a matched control group to support or refute the inference. This present study was conducted in a government tertiary care hospital where most of the patients were from lower socioeconomic status, and individuals visiting a dental hospital with the complaint of burning mouth were only included, which limits the generalization of the findings. Various covariates such as age, gender, and class and confounders such as habits and practices could have contributed to the results of the present study. In this study, cases and controls were age and gender matched, whereas variables related to oral health status remained unmatched. Hence, the results should be interpreted with caution.
Hence, proper diagnosis and management of burning mouth is of utmost importance, as it reflects age changes and multiple comorbidities and related medications and its complications, which precipitate as burning mouth with pain and suffering.
Further longitudinal studies including participants from various social classes might help in identifying the etiologic factors for burning mouth among these individuals.
| Conclusions|| |
A statistically significant very weak negative correlation was found between salivary flow rate and dental caries among individuals with burning mouths compared to those without burning mouths. Hence, salivary flow is related to burning mouths and dental caries.
Authors acknowledge Dr. Vijayalakshmi K R (Dept of Oral Medicine and Radiology) for being supportive throughout the study.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]