Smell, taste and trigeminal disorders in a 65-year-old population
In this study, chemosensory function (smell and taste) was investigated in 223 individuals (123 men, 100 women), randomly selected from study sample of the OsloMunn65 study.
The aim of the study was to determine the prevalence of smell, taste and burning mouth sensation in a 65-year-old population in Oslo, Norway, and to investigate associations between these disorders and gender, the presence of chronic diseases and use of medications, smoking, and salivary secretion rates.
According to results from the Sniffin´ Sticks test and Taste Strips test, 34% of the participants had smell disorders (28% hyposmia (reduced smell function) and 6% anosmia (total loss of smell)), 28% had taste disorders (21% hypogeusia (reduced taste function) and 7% ageusia (total loss of taste)) and burning mouth sensation was reported by 4% of the participants. A combination of both smell and taste disorders was present in 13% of the participants.
Regarding taste function, sweet taste was most often identified correctly, while sour taste was least often identified correctly in all four concentrations. In addition, the present study showed that women had more sensitive smell- and taste function than men. Self-reported smell perception was significantly lower in anosmic individuals than to hyposmic and
normosmic participants. Hyposmic individuals also scored their smell perception significantly lower compared to normosmic participants. However, the majority of affected individuals had low awareness of reduced smell and taste function, and no significant differences in self-reported taste perception were found between normogeusic, hypogeusic and ageusic participants. Furthermore, within this study population, some diseases and medications were associated with chemosensory disorders and burning mouth sensation.
33 Figure 2. Prevalence of chemosensory disorders
As mentioned, this study showed an overall low awareness of reduced smell and taste function among affected individuals. Furthermore, there was a low agreement between the results for self-reported smell and taste and the measured values. Since participants in this study represent the general population and not a selected group of people suffering from known chemosensory loss, participants with reduced smell perception may not have been aware of their condition. The visual analogue scale used in the present study has previously been used to investigate self-reported smell and taste perception in patients with Sjögren’s syndrome and healthy individuals (74, 75, 109, 110). Rusthen et al. found a significant positive correlation between measured and self-reported smell and taste ability in Sjögren’s patients (74). Landis et al. did not find a significant correlation between self-reported olfactory function prior to olfactory testing and measured olfactory function in healthy individuals (110). It might be speculated that the use of VAS for assessment of self-reported chemosensory function might be more suited when individuals with specific disorders are included rather than individuals from the general population. The fact that the present study showed low agreement between measured and self-reported smell and taste scores may indicate that smell and taste perception assessed by a VAS might be subject to individual interpretation. Considering this, the use of VAS for assessment for self-reported olfactory and gustatory function in a general population might be more suitable in longitudinal studies. They can be used to compare changes in VAS scores from start to follow up rather than comparing scores between individuals in a cross-sectional study.
34
Regarding the examination of gustatory (taste) function, taste strips (Burghart Messtechnik GmbH, Wedel, Germany) can be used for both lateral testing of the tongue and whole mouth testing (81). The lateral test enables detection of function separately on both sides of the tongue. However, since the aim of this study was to investigate an overall prevalence of taste disorders and not disorders related to specific regions of the tongue or nerves, the whole mouth testing method was used. It can be speculated that this gives a more realistic picture of the taste perception and is more relevant for the participants who uses taste receptors throughout the oral cavity at the same time.
Olfactory function was tested using Sniffin` Sticks-Identification test (Burghart Messtechnik GmbH, Wedel, Germany) consisting of 12 felt-tip odor pens. Ideally, a test including both threshold, discrimination and identification resulting in a TDI-score (threshold,
discrimination, identification), would give a more comprehensive assessment of the
olfactory function. However, due to time limitation in this study, only identification test for screening of olfactory function was performed.
In the present study, participants were asked if they had experienced a burning sensation in the mouth. They were also asked to specify the location of the burning sensation.
Disturbances in the trigeminal nerve may often lead to a burning mouth sensation. However, for diagnosing trigeminal disorders a more comprehensive examination and recording of symptoms would have been necessary. Because the burning mouth sensation was assessed through a few questions with no further examination, we decided to not use the term burning mouth syndrome that would have required a more strict assessment to diagnose (111).
The individuals included in the chemosensory examination also answered the OHIP-14 questionnaire. A significantly higher percentage of individuals with ageusia (27%) reported negative impact on OHRQoL (“Fairly often” or “Very often” to at least one of the OHIP-14 items) compared to normogeusic participants (6%). No significant association was found between hypogeusic (15%) and ageusic or normogeusic participants. Regarding smell function, a significant larger proportion of hyposmic participants (18%) reported negative impact on OHRQoL compared to normosmic participants (6%). No significant association was found between anosmic (7%) and hyposmic or normosmic participants. However, the power in these analyses can be discussed due to small samples of individuals with different severity of smell and taste disorders. In addition, the applicability of the OHIP-14 instrument in these analyses can be discussed. Even though the chemosensory function includes physiological processes that takes place in the oral cavity and adjacent tissues, some individuals might not
35
consider smell and taste function as a part of oral health when answering the oral health-related quality of life measure.
36
Discussion of major findings
The results indicated a substantial need for periodontal treatment among this population of 65-year-old Oslo citizens. By reporting the stages and grades of periodontitis in the
population, this work also provides information about the proportion of individuals that requires different levels of treatment complexity, and may help for planning the resources in dental services. To be able to prevent an increase of periodontal disease in the elderly population in the years to come, it will be of importance that dental health professionals are able to both detect periodontitis at early stages, and help in the prevention of this disease.
The risk indicators for severe periodontitis revealed in this study, i.e. non-western country of birth, diabetes type 2 and smoking, are important to highlight in order to ensure awareness among high risk individuals, but also among health authorities, and medical and dental professionals, so that the necessary preventive measures are initiated. Furthermore, the results from the present work indicating that periodontitis in early stages does not have a great impact on oral health-related quality of life in affected individuals, and highlights the importance of regular dental visits so that these stages of periodontitis can be discovered and necessary treatment be initiated. It is also important for dental professionals to be able to inform and advise patients about any necessary health behavior changes. Such preventive programs have shown to have a positive effect on reducing periodontitis (112-115).
The results showed that one-third of the participants had impaired smell function and more than one fourth had impaired taste function. However, the results also showed low
awareness of chemosensory disorders among affected individuals indicating that these disorders might not have a large impact on the life of individuals in the present sample.
Nevertheless, it is important to raise awareness of possible changes in these senses throughout life, for example as a result of diseases or medications more frequent used in older age, in order to prevent any harmful consequences such as negative changes in dietary composition or difficulties of detecting smoke or other dangerous situations. Therefore, this study indicates a need for attention towards detection, diagnostics and treatment of
chemosensory disorders in the Norwegian health sector.
37
Concluding remarks and future perspective
This thesis provides new knowledge about the prevalence of periodontitis and
chemosensory disorders among a large sample of 65-year-olds living in Oslo. In addition, the thesis highlights possible risk indicators for these conditions as well as the young elderly individuals´ awareness of these conditions and the possible effects on their oral health-related quality of life.
The present work showed that approximately half of the participants had periodontitis, and the majority of these had unstable, recurrent periodontitis. However, there was no
significant difference in the proportion of individuals reporting a negative impact on OHRQoL in non-periodontitis participants compared to individuals with periodontitis. The present work also indicated a low awareness of chemosensory disorders among the affected individuals. Lack of awareness in relation to diseases in general prevent individuals seeking health services until the disease has progressed to a state where more complex treatment is needed. Therefore, preventive measures and oral health advices to the population are important for preventing the progression and negative consequences of oral diseases. In addition, in order to prevent an increase in burden of diseases among the elderly in the years to come, information that strengthens the awareness of healthcare personnel,
including dentists, general physicians, and staff in nursing homes, etc., about conditions that can affect oral health will be increasingly important. Furthermore, appropriate knowledge about preventive measures that should be implemented for individuals at risk will be crucial.
In order to achieve this, interdisciplinary collaboration across different health disciplines will be important in the years to come.
At present, it can be expected that the participants in the OsloMunn65-study mostly use private dental services. According to the current subsidized scheme for dental services in Norway, patients can receive subsidized treatment in relation to certain diagnoses, e.g.
periodontitis – a diagnosis scheme. However, when individuals receive home care services or are living in a nursing home, they have the right to public dental services free of charge independent of diagnoses – a budget-based scheme. Therefore, as the proportion of elderly people in the population increases, the need for public dental services will most likely also increase. This trend will either require more funding of the public dental health services, or a change in the current system structure. Data from the present work contribute with
prevalence data, which may be of use for planning future health services.
38
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