|Year : 2019 | Volume
| Issue : 1 | Page : 17-22
Taste function and salivary analysis in patients with oral sensorial complaints
Neelima Gupta1, Rachana Rai2, Seema Garg3, HC Taneja1, MS Bhatia4, Lakshmi Vaid1
1 Department of Otorhinolaryngology, University College of Medical Sciences and GTB Hospital, Delhi, India
2 Department of Otorhinolaryngology, District Hospital, Gyalshing, Sikkim, India
3 Department of Biochemistry, University College of Medical Sciences and GTB Hospital, Delhi, India
4 Department of Psychiatry, University College of Medical Sciences and GTB Hospital, Delhi, India
|Date of Web Publication||24-Jun-2019|
Dr. Neelima Gupta
Department of Otorhinolaryngology, University College of Medical Sciences and GTB Hospital, A-304, Abhyant Apartment, Vasundhara Enclave, Delhi - 110 096
Source of Support: None, Conflict of Interest: None
Background: Taste dysfunction is a troublesome condition which causes subjective discomfort, impairs appetite, and leads to decrease in food intake. Patients often present to otorhinolaryngologists with a complaint of burning sensation in the mouth and associated taste dysfunction. We sought to study the taste dysfunction and do salivary analysis in these patients because studies reporting objective evidence of taste dysfunction in patients with such oral sensorial complaints (OSCs) are scarce. Materials and Methods: Thirty-five patients with OSCs and taste disturbances; and 35 healthy controls with no oral complaints and no taste disturbances were studied. Objective taste score was calculated using impregnated filter paper strips. Whole unstimulated salivary flow, salivary ions estimation (Na+ and K+), and psychometric profile assessment using the Oral Health Impact Profile-14 questionnaire and Depression Anxiety Stress Scale questionnaire were done. Results: The mean taste score in the OSC group was 20.80 ± 2.753, and in controls, it was 28.11 ± 2.564, showing a statistically significant difference. About 54% of the cases had decreased taste function. The whole unstimulated salivary flow rate (mL/min) in cases was 0.58 ± 0.10, and in controls, it was 0.78 ± 0.73; difference being statistically not significant (P = 0.066). Salivary ions showed higher levels in cases. The psychometric profile showed a higher rate of depression and stress in cases and a higher oral health impact score. Conclusion: We concluded that there is objective evidence of taste aberration in patients with OSCs. The subjective grading of reported taste dysfunction did not correlate with the objective taste scores, and there was an increased incidence of depression, anxiety, and stress in patients with OSCs and taste dysfunction.
Keywords: Burning mouth, salivary analysis, taste dysfunction
|How to cite this article:|
Gupta N, Rai R, Garg S, Taneja H C, Bhatia M S, Vaid L. Taste function and salivary analysis in patients with oral sensorial complaints. Indian J Oral Health Res 2019;5:17-22
|How to cite this URL:|
Gupta N, Rai R, Garg S, Taneja H C, Bhatia M S, Vaid L. Taste function and salivary analysis in patients with oral sensorial complaints. Indian J Oral Health Res [serial online] 2019 [cited 2020 Feb 23];5:17-22. Available from: http://www.ijohr.org/text.asp?2019/5/1/17/261149
| Introduction|| |
The sense of taste contributes to evaluating the quality of nutrients, distinguishing between safe and dangerous foods, determining food preferences and food intake, and consequently, to nutritive, energy, and electrolyte balance of an individual. Taste cells detect sugars, amino acids, poisons, acids, and minerals, which tastants are usually cues for sweet, umami, bitter, sour, and salty tastes, respectively. These five taste qualities are called basic tastes because each of them has distinct individual taste and are believed to be detected by different taste cells.
Taste disturbance is a fairly rare disorder in healthy controls, but the exact prevalence is unknown. In the United States, 0.6% of adults had taste problems, and Bergdahl M and Bergdahl J found that 7.2% of the adult Swedish population had metallic, salty, or bad taste in the mouth.
Taste disturbance is often associated with local, systemic, and psychological factors. The first group includes factors such as low salivary flow rate, burning mouth syndrome (BMS), candidiasis, and the number of amalgam-filled surfaces. The second group consists of factors with the systemic origin, that is, low zinc concentration, hormone disturbances, head trauma, viral infections, irradiation, and adverse effects of medication. The third group comprises psychological factors such as depression and stress.
The idiopathic sensorial disturbances of BMS, taste disturbances (dysgeusia), and dry mouth (xerostomia) were recognized as one entity and given the generic name of oral sensorial complaints (OSCs) by Granot and Nagler. However, they said that not all patients with OSC complain of all three disturbances, and the underlying mechanism of OSC is still not clear.
We evaluated 35 patients with OSCs who had associated taste disturbances. One of the main diagnoses with these presenting complaints is BMS. It is characterized by a painful burning sensation of the oral cavity without any mucosal abnormalities and affects women seven times more frequently than men.
Saliva is the principal component of the external environment of the taste receptor cells and as such plays a role in the taste sensitivity. It protects the taste receptor from dryness-induced and bacterial infection-induced damages, and thus prevents the taste disorders that might have otherwise occurred.
Over the years, various tests have been devised for taste testing. Electrogustometry is based on a weak electrical signal producing a sour taste when applied to the taste receptors. In addition, tests based on the chemical stimuli are frequently applied using a variety of materials, for example, filter paper discs, taste tablets, cotton swabs, edible wafers, taste strips,, or liquids.,,
Although taste aberrations are common in patients diagnosed with OSCs, objective taste estimation has not been commonly attempted in these patients. An objective score can help us in reporting the severity of the disease, whether or not, it correlates with the subjective reporting of complaints and in quantifying the response to intervention in these conditions. We evaluated the taste function using filter paper strips impregnated with tastants (sweet, sour, bitter, and salty). We also correlated the taste dysfunction with the psychometric profile of the patients, salivary ionic composition, salivary flow rate, and Oral Health Impact Profile (OHIP) in an attempt to establish a clinical profile.
| Materials and Methods|| |
Thirty-five patients in the age group of 15–70 years, with OSCs and taste disturbances and normal oral mucosa were classified as cases and 35 healthy controls with no oral complaints and no taste disturbances were used as controls.
Persons with a history of smoking, tobacco/paan/gutka chewing, head trauma, and irradiation or chemotherapy, history of recent dental procedures/denture being used, any chronic ear diseases, any complaints of smell disturbances, and any major systemic illnesses such as diabetes, hypothyroidism; and with a history of recent drug intake or chronic drug intake which is known to cause taste disturbances were excluded from the study.
Informed consent was obtained from the patients, and all the information provided was kept confidential. The study was approved by the Institutional Ethical Committee.
A detailed history was taken pertaining to the presenting complaints and perceived taste disturbances (onset, progression, duration, and associated complaints). The degree of severity of symptoms was graded using Visual Analog Score from scale 1 to5, 1 being the lowest, and 5 being the highest score. Detailed oral cavity examination was done, which included examination of orodental hygiene, tongue, hard and soft palate, buccal mucosa, and floor of the mouth.
Relevant data that were collected included taste score using impregnated filter paper strips, whole unstimulated salivary flow, and salivary ions estimation (Na+ and K+). Psychometric profile and the impact of taste disturbance were assessed using the OHIP-14 questionnaire, and Depression Anxiety Stress Scale (DASS) questionnaire.
The following concentrations and compounds were used for the taste strips: SWEET: 0.4, 0.2, 0.1, and 0.05 g/ml sucrose; SOUR: 0.3, 0.165, 0.09, and 0.05 g/ml citric acid; SALT: 0.25, 0.1, 0.04, and 0.016 g/ml sodium chloride; and BITTER: 0.006, 0.0024, 0.0009, and 0.0004 g/ml quinine hydrochloride. The filter paper strips of 8 cm length and tip area of 2 cm2 were dipped in the respective solutions (four concentrations each of the four basic tastes); air-dried and stored in labeled dry containers.
One hour before the testing, patients were asked not to eat or drink anything except water, not to smoke, and not to brush their teeth. The strips were placed on the right and left side of the anterior two-third of the extended tongue alternatively as shown in [Figure 1], resulting in a total of 32 trials. Before each administration of a strip, the mouth was rinsed with water. With the tongue still extended, the patient was asked to identify the taste from a list of four descriptors, that is, sweet, sour, salty, and bitter. To obtain an impression of overall gustatory function, the number of correctly identified tastes per side was added up to a “taste score.” The taste strips were presented in a randomized pattern to the patients keeping in mind that the taste presented was in increasing concentration.
Whole unstimulated salivary flow (ml/min)
The collection of the whole saliva was performed with patients at rest in a quiet room at least 1 h after eating. Patients were asked to collect saliva in their mouths and to spit it into a wide mouth container for 5 min, as shown in [Figure 2]. The salivary flow rates were estimated by measuring the volume of collected saliva over 5 min.
Salivary ions (Na+ and K+ mEq/L)
The collected saliva was centrifuged and stored at −20° until analyzed for sodium and potassium levels within 1–2 weeks after collection. This methodology was based on previous studies which have reported that saliva remains stable with respect to the parameters analyzed under such conditions. Salivary Na+ and K+ ions were analyzed using ion selective electrode method performed on autoanalyzer (ECOLYTE/COMBILINE).
Psychometric tests-Depression Anxiety Stress Scale Questionnaire
The DASS is a 42-item questionnaire which includes three self-report scales designed to measure the negative emotional states of depression, anxiety, and stress. Each of the three scales contains 14 items, divided into subscales of 2–5 items with similar content. Respondents were asked to use 4-point severity/frequency scales to rate the extent to which they had experienced each state over the past week., [Table 1] shows the grading of the scores on the DASS scoring.
Oral Health Impact Profile Questionnaire
The OHIP-14 is a short form of OHIP-49, consisting of two items for each of the seven subscales in the source instrument (functional limitation, physical pain, psychological discomfort, physical disability, psychological disability, social disability, and handicap). Each item asks about the presence of the functional or psychosocial impact associated with problems involving the teeth, mouth, and dentures. Items were scored on a Likert-type frequency scale as follows: never, hardly ever, occasionally, fairly often, and very often. The cumulative score was calculated, and higher scores were indicative of higher impact on the oral health of the patients.
| Results|| |
A total of 70 individuals (35 cases and 35 controls) were studied. Group 1 consisted of 35 cases with OSCs (group), and Group 2 consisted of 35 controls. The age of the patients ranged from 27 to 54 years with a mean age being 37.77 years in cases and 37.63 years in controls. The cases consisted of 17 males and 18 females, and controls consisted of 16 males and 19 females.
The mean taste score in the OSC group was 20.80 ± 2.753, and in controls, it was 28.11 ± 2.564, as shown in [Table 2]. Tukey test was used to compare the taste score between cases and controls; which was statistically significantly (P ≤ 0.001), implying, therefore, that taste scores were significantly less in patients.
The 10th percentile of the taste score of patients with no taste dysfunction was used to separate the normogeusic from hypogeusic patients. This score was 24. Using this score, we found that 19 (54%) cases had hypogeusia. All patients in the control group were normogeusic. Eight patients misidentified the sour taste as salty, and three patients could not identify the bitter taste in the OSC group. Spearman's correlation was used to correlate the objective taste score and subjective score. There was no statistically significant correlation between the two (P = 0.997).
The mean values of depression, anxiety, and stress score in cases and controls are presented in [Table 3]. Tukey test was applied to compare the depression score between the controls and cases, which was not statistically not significant (P = 0.299); comparison of stress score between the controls and cases was not statistically significant (P = 0.252).
|Table 3: Mean values of depression anxiety and stress scores in cases and controls|
Click here to view
The mean value of OHIP-14 in the case group was 11.43 ± 7.34, and in controls, it was 0.43 ± 0.73. Comparison of the OHIP-14 score between cases and controls, using Mann–Whitney test found statistically significant (P ≤ 0.001) difference between the two.
The whole unstimulated salivary flow rate (mL/min) in cases was 0.58 ± 0.10 (mean ± standard deviation), and in controls, it was 0.78 ± 0.73. The difference was not statistically significant (P = 0.066). Salivary analysis for ionic composition (Na+ and K+ mEq/L) was done in both cases and controls. The mean values of Na+ and K+ in cases and controls are presented in [Table 4].
The patients were considered to have taste dysfunction for individual tastes when they could identify only two higher concentrations of the particular taste. On the basis of this classification, we observed that 25% patients had sour taste dysfunction, 37% had bitter taste dysfunction, 34% had salt taste dysfunction, and 37% had sweet taste dysfunction.
| Discussion|| |
The chemosensory functions of taste and smell play a vital role in human physiology. They determine the flavor and palatability of foods and beverages and the warning of toxic and spoiled foodstuffs. Chemosensory dysfunctions have serious implications for the preservation of oral and systemic health, with dramatic effects on quality of life.
In our study, the psychophysical assessment of taste function was done using impregnated filter paper strips. Previous studies done using filter paper strips have found them to be useful for regional taste testing as they can be selectively applied on a particular region of the tongue and also found them to be easy to use and to have a longer shelf life as compared to liquid solutions.
In our study, the mean composite taste score of patients with OSCs was 20.80 ± 2.75; which was significantly lower than those of controls (28.11 ± 2.56), (P ≤ 0.001). The percentage of patients having taste dysfunction (patients with hypogeusia) was significantly higher in cases (54%) as compared with controls (P ≤ 0.001). These findings are consistent with the findings of a previous study by Hershkovich and Nagler, in which 71% of BMS and 66% of xerostomia patients had taste dysfunction. Just et al. also found decreased gustatory and somatosensory perception in BMS patients compared with healthy controls. In a recent study by Acharya et al., 45% of patients complained of taste disturbances. However, Bergdahl and Bergdahl found only a weak correlation between the burning mouth and perceived taste disturbance. In a study by Formaker and Frank, BMS patients had lower intensity ratings to higher concentrations of NaCl and sucrose than controls.
The subjective score of taste dysfunction was correlated with the composite taste score achieved after taste testing, and the correlation was found to be statistically not significant. It has been observed in a previous study by Soter et al. that most patients who complain of taste loss do so mistakenly since their problem usually reflects the loss of flavor sensation. Majority of patients may not respond accurately on the questionnaire items, hence, the subjective score may not be an actual indication of taste dysfunction.
Eleven patients in our study misidentified taste. Of these, eight misidentified sour taste as salty and three misidentified bitter taste. In a study by Formaker and Frank, it was seen that significant number of BMS patients misidentified taste stimuli as compared to controls; NaCl and citric acid being most commonly misidentified.
In a study, it was seen that there is an increased prevalence of so-called “supertasters” (persons with enhanced abilities to detect taste) among patients with BMS. Supertasters would be more likely to be affected by sensorial complaints because of their higher density of taste buds, each of which is surrounded by a basket-like collection of the pain neurons of the trigeminal nerve. However, among our cases, we could not substantiate any supertasters.
In our study, the mean of whole salivary flow rate of cases was 0.58 ± 0.10, which was lower as compared to controls 0.78 ± 0.73; but was not statistically significant (P = 0.066). These findings were consistent with previous studies., Other studies have also reported that xerostomia often coexists with BMS and taste aberrations. In a review article by Kolkka-Palomaa et al., it has been reported that most studies report a salivary flow rate same as that in controls; however, some studies that have reported decreased unstimulated salivary flow rate found no difference in stimulated salivary flow rate.
The difference of the mean of OHIP score in cases and controls was found to be statistically significant (P ≤ 0.001). The findings were similar to study done by Liu et al., where the mean score of OHIP-14 was significantly higher in patients with oral mucosal diseases (10.81 ± 9.01) compared with those of healthy controls (6.55 ± 6.73).
In a study from India, it was observed that oral diseases were significantly higher in anxiety patients (20%) than in depression (9%) and control group patients (5%). The results of the study showed a positive association between psychological alterations and changes in the oral mucosa, particularly conditions such as oral lichen planus, recurrent aphthous stomatitis, and BMS. Another study showed that illness, subjective oral dryness, state anxiety, perceived stress, depression, use of antiasthmatics, and trait anxiety were associated with taste disturbance. How psychological factors affect the mouth is still not clear, but a complex interaction of afferent messages may occur that affect the efferent impulses to the mouth. In our study, the percentage of patients with depression was higher in cases (40%) as compared to controls (28%). The percentage of patients with higher stress score was also found to be higher in cases (42%) than controls (28%) as shown in [Table 5]. These findings were similar to results of other studies.
|Table 5: Percentage of depression, anxiety, and stress in cases and controls|
Click here to view
In a study involving 74 BMS patients, it was found that 51.4% of patients reported a positive diagnosis, predominately depression. Maina et al. found a high degree of personality disorders among the BMS patients compared to both nonpsychiatric population sample and a population with other somatoform disorders. However, they concluded that their results could not determine whether or not the development of BMS precedes or follows the development of personality disorders.
Bergdahl et al. reported that when compared to control group, the BMS patients had a significantly lower score on the socialization scale and significantly higher scores on the somatic anxiety, muscular tension, and psychoasthenia scales. Grushka et al. also reported certain predominant personality disturbances in BMS patients, which tended to increase with increased pain.
In our study, the mean of salivary Na+ in cases was 21.66 ± 6.06, and in controls, it was 20.97 ± 5.63. The mean of K+ in cases was 22.29 ± 6.73, and in controls, it was 19.51 ± 6.11. The difference in Na+ levels was not significant, but one-way ANOVA when applied to potassium levels in saliva showed a statistically significant difference between cases and controls (P = 0.036). In a study, the concentrations of Na+, albumin, IgA, IgM, IgG, and lysozymes were significantly increased, but the K+ levels were found to be similar to those in controls. Therefore, our result did not concur with this study. On review of the literature, to the best of our knowledge, we could not find any study which had proven some linkage between potassium levels in the saliva and gustatory dysfunction. This aspect needs further investigation.
It is proposed that mucosal atrophy could result from salivary compositional alterations and is accompanied by local neuropathy caused by the induced nerve injury or dysfunction. Thus, disturbed perception at the lingual receptor level might be induced by the altered salivary ionic composition. In most cases, the reason for salivary compositional alterations is not known. The association between saliva and taste was also supported by the study published by Matsuo and Yamamoto, in which it was demonstrated that the whole saliva affected the taste responses of the chorda tympani nerve to the four standard chemical stimuli. This effect was dependent on the concentrations of the salivary electrolytes (NaCl, K, Cl, and HCO3).
| Conclusion|| |
We were able to demonstrate that there is objective evidence of taste aberration in patients with OSCs; which was missing evidence in most of the previous studies. The subjective grading of reported taste dysfunction did not correlate with the objective taste scores. The salivary flow rate was lower, the salivary potassium levels were higher, and there was an increased incidence of depression, anxiety, and stress in patients with OSCs and taste dysfunction.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form, the patients have given their consent for their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Fábián TK, Beck A, Fejérdy P, Hermann P, Fábián G. Molecular mechanisms of taste recognition: Considerations about the role of saliva. Int J Mol Sci 2015;16:5945-74.
Bergdahl M, Bergdahl J. Perceived taste disturbance in adults: Prevalence and association with oral and psychological factors and medication. Clin Oral Investig 2002;6:145-9.
Granot M, Nagler RM. Association between regional idiopathic neuropathy and salivary involvement as the possible mechanism for oral sensory complaints. J Pain 2005;6:581-7.
Hershkovich O, Nagler RM. Biochemical analysis of saliva and taste acuity evaluation in patients with burning mouth syndrome, xerostomia and/or gustatory disturbances. Arch Oral Biol 2004;49:515-22.
Krarup B. Electro-gustometry: A method for clinical taste examinations. Acta Otolaryngol 1958;49:294-305.
Sato K, Endo S, Tomita H. Sensitivity of three loci on the tongue and soft palate to four basic tastes in smokers and non-smokers. Acta Otolaryngol Suppl 2002;546:74-82.
Ahne G, Erras A, Hummel T, Kobal G. Assessment of gustatory function by means of tasting tablets. Laryngoscope 2000;110:1396-401.
Wrobel BB, Leopold DA. Clinical assessment of patients with smell and taste disorders. Otolaryngol Clin North Am 2004;37:1127-42.
Hummel T, Erras A, Kobal G. A test for the screening of taste function. Rhinology 1997;35:146-8.
Landis BN, Welge-Luessen A, Brämerson A, Bende M, Mueller CA, Nordin S, et al.
“Taste strips” - a rapid, lateralized, gustatory bedside identification test based on impregnated filter papers. J Neurol 2009;256:242-8.
Mueller C, Kallert S, Renner B, Stiassny K, Temmel AF, Hummel T, et al.
Quantitative assessment of gustatory function in a clinical context using impregnated “taste strips”. Rhinology 2003;41:2-6.
Henkin RI, Gill JR, Bartter FC. Studies on taste thresholds in normal man and in patients with adrenal cortical insufficiency: The role of adrenal cortical steroids and of serum sodium concentration. J Clin Invest 1963;42:727-35.
Gudziol H, Hummel T. Normative values for the assessment of gustatory function using liquid tastants. Acta Otolaryngol 2007;127:658-61.
Pingel J, Ostwald J, Pau HW, Hummel T, Just T. Normative data for a solution-based taste test. Eur Arch Otorhinolaryngol 2010;67:1911-7.
Balasubramaniam R, Klasser GD, Delcanho R. Separating oral burning from burning mouth syndrome: Unravelling a diagnostic enigma. Aust Dent J 2009;54:293-9.
Jimson S, Rajesh E, Krupaa JR, Kasthuri M. Burning mouth syndrome. J Pharm Bioallied Sci 2015;7:194-6.
Grushka M, Epstein JB, Gorsky M. Burning mouth syndrome. Am Fam Physician 2002;65:615-20.
Lovibond SH, Lovibond PF. Manual for Depression Anxiety Stress Scales. 2nd
ed. Sydney: Psychology Foundation; 1995.
Crawford JR, Henry JD. The depression anxiety stress scales (DASS): Normative data and latent structure in a large non-clinical sample. Br J Clin Psychol 2003;42:111-31.
Slade GD, Spencer AJ. Development and evaluation of the oral health impact profile. Community Dent Health 1994;11:3-11.
Maheswaran T, Abikshyeet P, Sitra G, Gokulanathan S, Vaithiyanadane V, Jeelani S. Gustatory dysfunction. J Pharm Bioallied Sci 2014;6:S30-3.
Just T, Steiner S, Pau HW. Oral pain perception and taste in burning mouth syndrome. J Oral Pathol Med 2010;39:22-7.
Acharya S, Carlén A, Wenneberg B, Jontell M, Hägglin C. Clinical characterization of women with burning mouth syndrome in a case-control study. Acta Odontol Scand 2018;76:279-86.
Formaker BK, Frank ME. Taste function in patients with oral burning. Chem Senses 2000;25:575-81.
Soter A, Kim J, Jackman A, Tourbier I, Kaul A, Doty RL, et al.
Accuracy of self-report in detecting taste dysfunction. Laryngoscope 2008;118:611-7.
Bartoshuk LM, Grushka M, Duffy VB, Fast K, Lucchina L, Prutkin J, et al
. Burning mouth syndrome: Damage to CN VII and pain phantoms in CN V. Chem Senses 1999;24:609.
Kolkka-Palomaa M, Jääskeläinen SK, Laine MA, Teerijoki-Oksa T, Sandell M, Forssell H. Pathophysiology of primary burning mouth syndrome with special focus on taste dysfunction: A review. Oral Dis 2015;21:937-48.
Liu LJ, Xiao W, He QB, Jiang WW. Generic and oral quality of life is affected by oral mucosal diseases. BMC Oral Health 2012;12:2.
Suresh KV, Shenai P, Chatra L, Ronad YA, Bilahari N, Pramod RC, et al.
Oral mucosal diseases in anxiety and depression patients: Hospital based observational study from South India. J Clin Exp Dent 2015;7:e95-9.
Kalkur C, Sattur AP, Guttal KS. Role of depression, anxiety and stress in patients with oral lichen planus: A pilot study. Indian J Dermatol 2015;60:445-9.
] [Full text]
Rojo L, Silvestre FJ, Bagan JV, De Vicente T. Psychiatric morbidity in burning mouth syndrome. Psychiatric interview versus depression and anxiety scales. Oral Surg Oral Med Oral Pathol 1993;75:308-11.
Maina G, Albert U, Gandolfo S, Vitalucci A, Bogetto F. Personality disorders in patients with burning mouth syndrome. J Pers Disord 2005;19:84-93.
Bergdahl J, Anneroth G, Perris H. Personality characteristics of patients with resistant burning mouth syndrome. Acta Odontol Scand 1995;53:7-11.
Grushka M, Sessle BJ, Miller R. Pain and personality profiles in burning mouth syndrome. Pain 1987;28:155-67.
Matsuo R, Yamamoto T. Effects of inorganic constituents of saliva on taste responses of the rat chorda tympani nerve. Brain Res 1992;583:71-80.
[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]