# The association between oral health and nutritional status in older adults: a cross-sectional study

Claudine Khoury, Johan Samot, Catherine Helmer, Rafael Weber Rosa, Aurore Georget, Jean-Francois Dartigues, Elise Arrive

<figure><img src="image_1.png" /></figure>

## To cite this version:

Claudine Khoury, Johan Samot, Catherine Helmer, Rafael Weber Rosa, Aurore Georget, et al.. The association between oral health and nutritional status in older adults: a cross-sectional study. BMC Geriatrics, 2022, 22, pp.499. 10.1186/s12877-022-03133-0. hal-03757344

HAL Id: hal-03757344

https://hal.science/hal-03757344v1

Submitted on 22 Aug 2022

HAL is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

<figure><img src="image_2.png" /></figure>

Distributed under a Creative Commons CC BY 4.0 - Attribution - International License
RESEARCH

Open Access

<figure><img src="image_3.png" /></figure>

# The association between oral health and nutritional status in older adults: a cross-sectional study

Claudine Khoury<fnref n="1" />,², Johan Samot<fnref n="1" />,², Catherine Helmer³, Rafael Weber Rosa⁴, Aurore Georget⁵, Jean-François Dartigues³ and Elise Arrivé<fnref n="1" />,²*

**Abstract**

**Objectives:** This work aimed to describe the nutritional status of French older adults (age ≥ 90 years) and studied the association between oral health and nutritional status.

**Methods:** A cross-sectional study was carried out in 2014 among the participants of a cohort on cerebral and functional aging in France at their 25-year follow up (the PAQUID cohort). Nutritional status (Mini Nutritional Assessment [MNA]) and oral health status (number of decayed, missing, and filled teeth [DMFT], number of posterior occluding pairs, xerostomia [Xerostomia Inventory], and prosthetic rehabilitation) were recorded at the participants' living places by two dentists. Univariate and multivariate logistic regressions were used to explore the association between oral health and nutritional status, with adjustments for potential confounders. Odds ratios (OR) were estimated with their 95% confidence interval (CI).

**Results:** 87 participants were included in the analyses: 74.7% were females and the mean age was 94.1 years (± 3.0). Malnutrition or risk of malnutrition (MNA < 24) was present in 23 participants (26.4%), with only one having malnutrition. The mean DMFT score was 26.5 (± 5.3). The mean number of posterior occluding pairs was 1.5 (± 2.3). Twenty-one participants had xerostomia (24.1%). Only 8.1% of the participants had all their teeth or adequate dentures; 47.1% had inadequate dentures, while 44.8% had no dentures despite tooth loss. After adjustment, xerostomia (OR = 8.79; 95% CI = 2.38–39.10; *p* = 0.002) was found to be associated with malnutrition or risk of malnutrition.

**Conclusion:** Being at risk of malnutrition was common among people ≥ 90 years old and was associated with xerostomia. NCT04065828.

**Keywords:** Malnutrition, Oral health, Aged, Epidemiology, Mini Nutritional Assessment, Xerostomia, Dental occlusion

**Introduction**

Nutritional status is an important factor for general health in older adults [1]. Studies have reported a prevalence of undernourishment in older adults, between 4.3% and 90%, because of differences in the study populations and definitions [2]. The underlying causes can be divided

into primary (cognitive, behavioural, taste, and olfactory disorders) and secondary factors (adverse drug effects and comorbidities) [3]. These factors can lead to a loss of appetite, refusal to eat, and inability to prepare meals [3]. Malnutrition can increase the risk of falls [4] and frailty [5], and can lead to depression, decreased functional capacity, increased rates of infection, longer hospital stays, increased mortality, and increased economic burdens on the patient and society [2]. A French study showed that 7.4–14.8% of people aged 65 years and above

<footnote>*Correspondence: elise.arrive@u-bordeaux.fr</footnote>

<footnote n="1">¹ Université de Bordeaux, UFR d'Odontologie, Bordeaux, France
Full list of author information is available at the end of the article</footnote>
were undernourished based on the Mini Nutritional Assessment (MNA), and the associated factors were age, widowhood, low body mass index (BMI), dementia, depression, dependency, use of more than three drugs per day, low level of education, and low income [6].

Oral problems are common in older adults. Comorbidities and their treatments, as well as dependence, can cause or accentuate oral pathologies and complicate their management [7]. Therefore, older individuals are more likely to have certain oral conditions such as chronic periodontitis, root caries, precancerous and cancerous conditions, oral infections, xerostomia, also known as dry mouth, loss of teeth, and denture use [8–11]. Oral problems are likely to contribute to the altered nutritional status in older adults via avoidance of certain foods because of masticatory problems or oral pain. This may lead to digestive disorders [12]. In addition, oral health problems can affect the quality of life, social relationships, and diet in this population [2].

However, the relationship between oral status and nutritional status in older adults is still neglected. Most studies have been conducted in specific populations only, such as institutionalized individuals [2], and only four studies conducted in the general geriatric population could be identified in a recent systematic review including ten studies [13]. Associations were found between hard and soft tissue conditions of the mouth, xerostomia and subjective oral health and poor nutritional status. A meta-analysis showed that well-nourished subjects had a higher number of pairs of teeth compared to individuals with poor nutritional status who had a lower mean number of present teeth [14]. Furthermore, there were no studies that addressed people aged 90 years and above. The aim of this study was to investigate the nutritional status of French older adults (age ≥ 90 years) and the association between oral health status and nutritional status in this population. We hypothesized that poor oral health was associated with impaired nutritional status.

# Methods

## Study population and design

A cross-sectional oral sub-study was conducted on consenting participants who were seen at the 25-year follow up of the Personnes Agées QUID (PAQUID) cohort study [15, 16]. The PAQUID study is an ongoing cohort with the objective of describing the evolution of cognitive functions to identify predictive signs of and risk factors for dementia, and to study dependence in older adults, its risk factors, and consequences. This project started in 1988; 5554 individuals aged 65 years or above, living at home, and randomly selected from the electoral lists of Gironde and Dordogne, France, were invited to participate. Among them 3777 (68%) agreed; they were

representative of the elderly population of these two areas. In 2013–2014, 231 PAQUID participants still alive underwent the 25-year follow-up among them 197 were invited to participate in the oral sub-study (N=90) were similar in terms of age and sex to those who did not participate (N=117), but were less likely to be institutionalized and to have a low education level [15].

## Outcomes of interest

Nutritional status and oral health were assessed by two dentists at the participants' living place.

Standardized questionnaires were personally administered to either the participant or to a caregiver. The oral characteristics were recorded during an oral clinical examination in accordance with the WHO's recommendations [17] as described elsewhere [15].

Nutritional status was assessed using the full version of the MNA, which consists of a general health assessment, a dietetic assessment, anthropometric measures, self-perception of health and nutrition, and a global evaluation involving questions on living independently, prescription drug use, psychological stress, acute disease, mobility, dementia, and skin conditions [18]. The score, ranging from 0 to 30, is interpreted as follows: MNA ≥ 24 as normal nutritional status; 17 ≤ MNA ≤ 23.5 as at risk of malnutrition, and MNA < 17 as malnutrition [19].

Oral health was evaluated using the Decayed-Missing-Filled teeth index (DMFT index) on 32 teeth [17], the number of posterior occluding pairs on natural teeth or fixed prostheses except for wisdom teeth [20], the presence of oral pain ("Currently, do you have pain in your mouth"), xerostomia ("subjective feeling of dry mouth" — Xerostomia Inventory) [21], and prosthetic rehabilitation (no tooth loss or adequate dentures, inadequate dentures, or no dentures despite tooth loss).

Teeth with carious lesions or temporary fillings on the crown or root were considered decayed (D). Teeth were considered filled (F) if they had at least one permanent restoration (including crowns) without any caries on the crown or root [17]. Inadequate dentures were defined as the use of reliners or tissue conditioners, excessive wear of posterior teeth, lack of integrity, or problems with stability or retention [22]. Coronal and root conditions were assessed for each tooth individually. Tooth loss and the presence and adaptation of removable prostheses were assessed. The inter-observer reliability for the DMFT index, assessed using the intra-class correlation coefficient, was 0.99 (95% confidence
interval = 0.98–1.00), corresponding to excellent reliability [23].

## Other characteristics

Sociodemographic and medical characteristics were obtained from the existing PAQUID database. Sociodemographic variables included sex, age, education level, and living conditions. Medical variables included the presence of comorbidities (diabetes mellitus, Parkinson's disease, stroke, and myocardial infarction), number of medications used per day, psychotropic drug use, tobacco use, and dementia. At each follow-up visit every 2 or 3 years, dementia diagnosis was based on a three-step procedure: first, a neuropsychologist performed a neuropsychological evaluation at the participant's living place; second, participants suspected of dementia following this evaluation were examined by a neurologist or a geriatrician; and finally a definitive diagnosis of dementia, was made by a panel of independent neurologists, based on Diagnostic and Statistical Manual of Mental Disorders criteria (DSM-IV) [24]. Dependency was assessed using a hierarchical four-stage index that combines the Activities of Daily Living (ADL), the Instrumental Activities of Daily Living Scale (IADL), and mobility (assessed using the Rosow and Breslau scale). Participants were classified as having no dependency; mild dependency (dependent only in the Rosow scale); moderate dependency (dependent in the Rosow and IADL scales); and severe dependency (dependent in the ADL scale) [21].

## Statistical analysis

Nutritional status, oral health status, sociodemographic, and clinical characteristics were described as mean, standard error (SE), minimum (min), and maximum (max) values for quantitative variables, and percentages for qualitative variables.

We used univariate and multivariate logistic regressions to explore the association between nutritional status (MNA) as the dependent variable and oral health as explanatory variables (DMFT index, number of posterior occluding pairs, oral pain, xerostomia, and prosthetic rehabilitations). Odds ratios (ORs) were estimated with their 95% confidence intervals (CIs). MNA was categorized into two groups based on the global score obtained from the questionnaire: normal nutritional status (MNA ≥ 24, reference in the regression model) and nutritional status as the risk of malnutrition or malnutrition (MNA < 24). The association between MNA and oral health related variables, age, sex, education level, living alone, institutionalization, dementia, medication use, presence of comorbidities, or dependency was tested in univariate analyses. Variables associated with MNA in the univariate analysis with a conservative threshold of

25% were used in the multivariate analysis, along with age, which was forced in the multivariate model.

Participants who did not have complete data for dependent, explanatory, and adjustment variables (N=3) were excluded from the analysis.

Statistical analyses were performed with a level of significance of 0.05 using SAS software (version 9.4) and R software (version 3.2.3).

## Results

### Participants' descriptions

Among the 90 participants of the oral PAQUID study, three were excluded. The mean age of the remaining 87 participants was 94.1 years (±3.0; min=90.6 years; max=105.6 years). Most participants were females (74.7%), while almost three-quarters of the participants lived at home (Table 1). Twenty-four participants had dementia and 71.2% had other comorbidities. The number of medications used per day was 6.8 (±3.0; min=0; max=16). According to the hierarchical disability scale, only one participant had no dependency. Only one participant was a current tobacco consumer.

### Nutritional status

The mean MNA score was 25.5 (±3.7). Three-quarters of the participants (n=64; 73.6%) had a normal nutritional status, 22 were at risk of malnutrition (25.3%), and 1 had malnutrition (1.1%).

### Oral status

The mean DMFT score was 26.5 (±5.3) with a mean of 3.6 decayed teeth (±4.9), 4.8 filled teeth (±5.3), and 18.1 missing teeth (±9.2). The mean number of posterior occluding pairs was 1.5 (±2.3). Oral pain and xerostomia were reported in 6.9% and 24.1% of the participants, respectively. In the maxilla, 10 participants (11.5%) had all their teeth, 51 (58.6%) had partial tooth loss, 26 (29.9%) had total tooth loss and 50 (57.5%) used dentures. In the mandible, 11 participants (12.6%) had all their teeth, 58 (66.7%) had partial tooth loss, 18 (20.7%) had total tooth loss and 42 (48.3%) used dentures. Globally, 54 participants (62.1%) used dentures but, 84.0% of the maxillary dentures and 85.7% of the mandibular dentures were inadequate. There were also a few people (n=5) who did not use their dentures during meals.

### Association between oral health and nutritional status

The univariate analysis demonstrated that xerostomia was associated with being malnourished or at risk of malnutrition (OR=6.67; 95% CI=2.26–19.63; *p*=0.0006) as well as a one-unit decrease in the posterior occluding pairs (OR=0.69; 95% CI=0.49–0.99; *p*=0.041) (Table 2).
<table><caption>**Table 1** Participants' characteristics, PAQUID oral sub-study (n = 87), France, 2014</caption><thead><tr><th rowspan="2">Variables</th><th colspan="2">Total</th><th colspan="2">Normal nutritional status (n = 64)</th><th colspan="2">Malnutrition or at risk (n = 23)</th></tr><tr><th>N/Mean</th><th>(%)/(sd)</th><th>N/Mean</th><th>(%)/(sd)</th><th>N/Mean</th><th>(%)/(sd)</th></tr></thead><tbody><tr><td>Age (years), mean (sd)</td><td>94.1</td><td>(3.0)</td><td>94.0</td><td>(3.0)</td><td>94.5</td><td>(3.0)</td></tr><tr><td>Females (vs. Males)</td><td>65</td><td>(74.7)</td><td>44</td><td>(68.8)</td><td>21</td><td>(91.3)</td></tr><tr><td>Higher school level (vs. No)</td><td>73</td><td>(83.9)</td><td>54</td><td>(84.4)</td><td>19</td><td>(82.6)</td></tr><tr><td>Living alone (vs. No),</td><td>44</td><td>(50.6)</td><td>33</td><td>(51.6)</td><td>11</td><td>(47.8)</td></tr><tr><td>Institutionalized (vs. living at home)</td><td>23</td><td>(26.4)</td><td>12</td><td>(18.8)</td><td>11</td><td>(47.8)</td></tr><tr><td>Dementia (vs. No)</td><td>24</td><td>(27.9)</td><td>17</td><td>(27.0)</td><td>7</td><td>(30.4)</td></tr><tr><td>Number of medications per day, mean (sd)</td><td>6.8</td><td>(3.1)</td><td>6.3</td><td>(3.0)</td><td>8.2</td><td>(2.8)</td></tr><tr><td>Psychotropic intake (vs. No)</td><td>35</td><td>(40.2)</td><td>24</td><td>(37.5)</td><td>11</td><td>(47.8)</td></tr><tr><td>Presence of comorbidities* (vs. No)</td><td>62</td><td>(71.2)</td><td>46</td><td>(71.9)</td><td>16</td><td>(69.6)</td></tr><tr><td>Hierarchical disability scale</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>No or mild dependency</td><td>21</td><td>(24.1)</td><td>19</td><td>(29.7)</td><td>1</td><td>(8.7)</td></tr><tr><td>Moderate dependency</td><td>35</td><td>(40.2)</td><td>27</td><td>(42.1)</td><td>8</td><td>(34.8)</td></tr><tr><td>Severe dependency</td><td>31</td><td>(35.7)</td><td>18</td><td>(28.1)</td><td>13</td><td>(56.5)</td></tr><tr><td>DMFT index > 19 (vs. ≤ 19), n (%)</td><td>76</td><td>(87.4)</td><td>57</td><td>(89.1)</td><td>19</td><td>(82.6)</td></tr><tr><td>Posterior occluding pairs, mean (sd)</td><td>1.5</td><td>(2.3)</td><td>1.8</td><td>(2.5)</td><td>0.6</td><td>(1.1)</td></tr><tr><td>Oral pain (vs. No), n (%)</td><td>6</td><td>(6.9)</td><td>5</td><td>(7.8)</td><td>1</td><td>(4.3)</td></tr><tr><td>Xerostomia (vs. No), n (%)</td><td>21</td><td>(24.1)</td><td>9</td><td>(14.1)</td><td>12</td><td>(52.1)</td></tr><tr><td>Prosthetic rehabilitation, n (%)</td><td></td><td></td><td></td><td></td><td></td><td></td></tr><tr><td>No tooth loss or adequate dentures</td><td>7</td><td>(8.1)</td><td>6</td><td>(9.4)</td><td>1</td><td>(4.3)</td></tr><tr><td>Inadequate dentures</td><td>41</td><td>(47.1)</td><td>31</td><td>(48.4)</td><td>10</td><td>(43.5)</td></tr><tr><td>No dentures despite tooth loss</td><td>39</td><td>(44.8)</td><td>27</td><td>(42.2)</td><td>12</td><td>(52.2)</td></tr></tbody></table>

DMFT Decayed-Missing-Filled Teeth index. Sd Standard deviation. MNA Mini Nutritional Assessment

Sex, posterior occluding pairs, xerostomia, living in an institution, number of medications used per day, and the disability scale were identified by the univariate analysis at the 25% threshold and were included in the multivariable model.

After adjustment for these variables and for age, only xerostomia remained associated with being malnourished or at risk of malnutrition was associated with xerostomia (OR = 8.79; 95% CI = 2.38–39.10; p = 0.002) (Table 2).

## Discussion

This study demonstrated that about 25% of these participants aged 90 years or over were at risk of malnutrition while only 1.1% was malnourished. Together, the prevalence was quite high compared to the prevalence reported in the literature and corresponded more to prevalence rates found in hospital settings [25]. In general settings, Torres et al. [6] reported a prevalence of poor nutritional status (at risk of malnutrition and malnutrition, assessed by MNA) of 7.4–14.8% in subjects having a mean age of 75.5 years, while Nykänen et al. [10] reported a prevalence of possible malnutrition (at risk of malnutrition and malnutrition, assessed by MNA short

form) of 15% in a sample with a mean age of 81 years. This difference could be explained by the fact that the participants in the present study were older than those in these previous studies. This is indeed, to our knowledge, the first study reporting findings about such aged population.

As discussed elsewhere [15], our study sample presented with important dental care needs: 3.6 decayed teeth which is well above those of national studies conducted in other countries, with untreated caries representing a small part of the DMFT (DT ≤ 0.5), even in people > 75 years old [26]; about 85% of the prosthesis not adapted which is common, even in younger adults [22]. However, these conditions were not associated with poor nutritional status.

Xerostomia was independently associated with malnutrition or risk of malnutrition in our population. This was in concordance with the study conducted by Nykänen et al. [10] where dry mouth was independently associated with the risk of malnutrition. Xerostomia may influence nutritional status due to oral discomfort, taste aberrations, dental caries, oral infections, and difficulty retaining prostheses. A recent study found that xerostomia was reported by 24% of the participants with the mean
<table><caption>**Table 2** Factors associated with the probability of malnutrition or risk of malnutrition defined by a MNA score < 24, PAQUID oral sub-study (n = 87), France, 2014</caption><thead><tr><th rowspan="2">Variables</th><th colspan="3">Univariate analysis</th><th colspan="3">Multivariate analysis</th></tr><tr><th>OR</th><th>95% CI</th><th>p-value</th><th>OR</th><th>95% CI</th><th>p-value</th></tr></thead><tbody><tr><td>Age (years), mean (sd)</td><td>1.06</td><td>[0.90 - 1.23]</td><td>0.485</td><td>1.10</td><td>[0.90-1.34]</td><td>0.150</td></tr><tr><td>Females (vs. Males)</td><td>4.77</td><td>[1.23 - 31.65]</td><td><strong>0.047</strong></td><td>4.55</td><td>[0.75 - 48.43]</td><td>0.326</td></tr><tr><td>Higher school level (vs. No)</td><td>0.88</td><td>[0.26 - 3.50]</td><td>0.843</td><td></td><td></td><td></td></tr><tr><td>Living alone (vs. No),</td><td>0.86</td><td>[0.33 - 2.24]</td><td>0.759</td><td></td><td></td><td></td></tr><tr><td>Institutionalized (vs. living at home)</td><td>3.97</td><td>[1.42 - 11.36]</td><td><strong>0.009</strong></td><td>1.38</td><td>[0.28 - 6.51]</td><td>0.535</td></tr><tr><td>Dementia (vs. No)</td><td>1.18</td><td>[0.40 - 3.31]</td><td>0.752</td><td></td><td></td><td></td></tr><tr><td>Number of medications per day, mean (sd)</td><td>1.23</td><td>[1.05 - 1.48]</td><td><strong>0.015</strong></td><td>1.07</td><td>[0.86 - 1.35]</td><td>0.142</td></tr><tr><td>Psychotropic intake (vs. No)</td><td>1.53</td><td>[0.58 - 4.03]</td><td>0.388</td><td></td><td></td><td></td></tr><tr><td>Presence of comorbidities<sup>a</sup> (vs. No)</td><td>0.89</td><td>[0.32 - 2.65]</td><td>0.834</td><td></td><td></td><td></td></tr><tr><td>Hierarchical disability scale</td><td></td><td></td><td><strong>0.020</strong></td><td></td><td></td><td>0.186</td></tr><tr><td>No or mild dependency</td><td>1.00</td><td>-</td><td></td><td>1.00</td><td>-</td><td></td></tr><tr><td>Moderate dependency</td><td>2.81</td><td>[0.62 - 20.05]</td><td></td><td>3.77</td><td>[0.57 - 37.41]</td><td></td></tr><tr><td>Severe dependency</td><td>6.86</td><td>[1.60 - 47.94]</td><td></td><td>6.83</td><td>[0.87 - 74.81]</td><td></td></tr><tr><td>DMFT index > 19 (vs. ≤ 19), n (%)</td><td>0.58</td><td>[0.15 - 2.21]</td><td>0.428</td><td></td><td></td><td></td></tr><tr><td>Posterior occluding pairs, mean (sd)</td><td>0.69</td><td>[0.49 - 0.99]</td><td><strong>0.041</strong></td><td>0.66</td><td>[0.37 - 0.98]</td><td>0.089</td></tr><tr><td>Oral pain (vs. No), n (%)</td><td>0.54</td><td>[0.06 - 4.81]</td><td>0.579</td><td></td><td></td><td></td></tr><tr><td>Xerostomia (vs. No), n (%)</td><td>6.67</td><td>[2.26 - 19.63]</td><td><strong>0.0006</strong></td><td>8.79</td><td>[2.38 - 39.10]</td><td><strong>0.002</strong></td></tr><tr><td>Prosthetic rehabilitation, n (%)</td><td></td><td></td><td>0.618</td><td></td><td></td><td></td></tr><tr><td>No tooth loss or adequate dentures</td><td>1.00</td><td>-</td><td></td><td></td><td></td><td></td></tr><tr><td>Inadequate dentures</td><td>1.94</td><td>[0.21 - 18.07]</td><td></td><td></td><td></td><td></td></tr><tr><td>No dentures despite tooth loss</td><td>2.67</td><td>[0.29 - 24.64]</td><td></td><td></td><td></td><td></td></tr></tbody></table>

DMFT Decayed-Missing-Filled Teeth index. Sd Standard deviation. MNA Mini Nutritional Assessment. OR Odds Ratio. CI Confidence Interval

age of 67.6 ± 6.1 years, and tended to be associated with a two-fold increased risk of incident malnutrition (adjusted hazard ratio = 1.99; 95% CI: 0.93–4.28; *p* = 0.077) [27]. In addition, a randomized study examined the effectiveness of interventions focusing on xerostomia and nutritional status among home-care clients aged 75 years or above who were malnourished or at risk of malnutrition [28]. Among the participants who received both interventions, xerostomia decreased by 30% while malnutrition or risk of malnutrition decreased by 61%. These studies, along with the present study, indicate the importance of xerostomia screening and care in older adults with nutritional problems.

A recent meta-analysis showed that poor nutritional status was associated with lower number of pairs of teeth/functional teeth units [14]. This is in contrast with our study, where a one-unit decrease in the posterior occluding pairs was associated with the nutritional status in univariate analysis but this association did not remain after adjustment. Although it is clear that chewing problems can influence dietary intake and food choices, they may not necessarily lead to a poor nutritional status. For example, fruits and vegetables avoided by edentulous

people can be replaced by juices. The consumption of particular foods appears to influence quality of life more than nutritional status [29].

In our study, prosthetic rehabilitation was not associated with malnutrition. Interventional studies are discordant on this topic. For instance, a 2000 study by Moynihan et al. [25] found no dietary changes after fixed or removable prosthetic rehabilitation. In contrast, McKenna et al. [30] demonstrated a significant increase in the MNA score 12 months after denture use in a randomized trial. Further research is needed to clarify the impact of prosthetic rehabilitation on nutritional status.

The limitations of our study included a restricted sample size, due to the extremely old study population. This limitation could have resulted in a lack of power and precision reflected by our wide Cis. Any conclusions drawn from the present data should, if possible, be replicated with a larger sample size. Furthermore, it was a cross-sectional study that could not establish causality. Finally, the participants were from a cohort initiated in 1988, and less than half people from this cohort agreed to participate in the oral sub-study, so the participants were selected as a necessity. Therefore,

<footnote>a Presence of diabetes, Parkinson's disease, history of myocardial infarction or stroke</footnote>
caution must be exercised while generalizing the results of this study to the entire population.

Our study has several strengths. First, although most studies on geriatric population's oral health were conducted in institutionalized individuals, our study was carried out mainly in participants living at home. Indeed, PAQUID initially included people living at home and at the 25-year follow up, only about one quarter of them were institutionalized. As a result, we could study the nutritional status and oral health in a population that is often neglected in studies due to difficult access. We were particularly interested in the home-based older adults because of undetected oral health problems in this population due to limited contact with the health care system. Second, we focused on a very old population aged ≥ 90 years who was never studied before. Third, data were collected by trained examiners using validated and reproducible indices. Finally, we considered potential confounding factors while investigating the association between oral health and nutritional status. Therefore, our multivariate analysis provided a robust basis for the current knowledge.

In conclusion, nutritional status and oral health are often poor in older adults. Our study highlights the importance of oral health, particularly xerostomia, associated with nutritional status, in older adults. Systematic joint screening of oral and nutritional problems in older adults could lead to improvements in their general health and quality of life. Information and training of health professionals working in institutions or who are in contact with older adults could improve professional practices, including screening and care of xerostomia. Our findings need to be supported by additional longitudinal and interventional studies, addressing both aspects, to provide a better understanding of the relationship between oral health and nutritional status, and to improve the general health and quality of life in older adults.

**Abbreviations**

CI: Confidence interval; DMFT: Decayed, missing, filled teeth; IADL: Instrumental Activities of Daily Living Scale; MNA: Mini nutritional assessment; SD: Standard deviation.

**Acknowledgements**

We thank all the participants who agreed to participate in this study. We also thank Rodolphe Thiébaut and Karen Leffondré for their methodological support, Sebastien Marchi for his support in conducting the research, the PAQUID psychologists for presenting our study to the participants, Marie-Hélène Sage for making appointments with the participants, and Severine Martiren, Belinda Bastol, and Catherine Maldonado for data management. We also acknowledge Colgate Palmolive as they kindly offered 20 mL of Meridol toothpaste and a Meridol toothbrush to each participant.

**Authors' contributions**

CK, CH, JFD and EA were involved in the conception and design of the study. JS and RWR collected the data. CK and AG performed statistical analysis. CK

wrote the manuscript with the support of EA. CH and JFD performed the critical revision of the manuscript. All authors read and approved the final manuscript.

**Funding**

This study was funded by the Bordeaux Teaching Hospital (CHUBX 2013/04).

**Availability of data and materials**

The datasets analysed during the current study are not publicly available because French regulatory imposes controlled access to participants' personal data but are available from the corresponding author on reasonable request.

**Declarations**

**Ethics approval and consent to participate**

The study protocol was approved by the Ethics Committee of the Bordeaux Teaching Hospital named "Comité de Protection des Personnes Sud-Ouest et Outre Mer III", under the reference DC2013/73. Informed consent was obtained from all participants. Dementia patients were also involved in the study and informed consent was obtained from their legally authorized representatives. All methods were carried out in accordance with the Declaration of Helsinki.

**Consent for publication**

Not applicable.

**Competing interests**

The authors declare that they have no competing interests.

**Author details**

¹Université de Bordeaux, UFR d'Odontologie, Bordeaux, France. ²CHU de Bordeaux, Pôle de médecine et chirurgie bucco-dentaire, Bordeaux, France. ³Université de Bordeaux, INSERM, Bordeaux Population Health Research Center, UMR 1219, Bordeaux, France. ⁴Université de Bordeaux, ISPED, Bordeaux, France. ⁵CHU de Bordeaux, USMR, Pôle de Santé publique, Bordeaux, France.

Received: 28 January 2022 Accepted: 9 May 2022

Published online: 10 June 2022

**References**

1. Lorenzo-López L, Maseda A, de Labra C, Regueiro-Folgueira L, Rodríguez-Villamil JL, Millán-Calenti JC. Nutritional determinants of frailty in older adults: A systematic review. BMC Geriatr. 2017;17(1):108.

2. Van Lancker A, Verhaeghe S, Van Hecke A, Vanderwee K, Goossens J, Beeckman D. The association between malnutrition and oral health status in elderly in long-term care facilities: a systematic review. Int J Nurs Stud. 2012;49(12):1568-81.

3. Droogsma E, van Asselt D, De Deyn PP. Weight loss and undernutrition in community-dwelling patients with Alzheimer's dementia: From population based studies to clinical management. Z Gerontol Geriatr. 2015;48(4):318-24.

4. Torres MJ, Féart C, Samieri C, Dorigny B, Luiking Y, Berr C, et al. Poor nutritional status is associated with a higher risk of falling and fracture in elderly people living at home in France: the Three-City cohort study. Osteoporos Int J. 2015;26(8):2157-64.

5. Artaza-Artabe I, Sáez-López P, Sánchez-Hernández N, Fernández-Gutierrez N, Malafarina V. The relationship between nutrition and frailty: Effects of protein intake, nutritional supplementation, vitamin D and exercise on muscle metabolism in the elderly. A systematic review Maturitas. 2016;93:89-99.

6. Torres MJ, Dorigny B, Kuhn M, Berr C, Barberger-Gateau P, Letenneur L. Nutritional status in community-dwelling elderly in France in urban and rural areas. PLoS ONE. 2014;9(8): e105137.

7. Ghezzi EM, Ship JA. Systemic diseases and their treatments in the elderly: impact on oral health. J Public Health Dent. 2000;60(4):289-96.

8. Gueiros LA, Soares MSM, Leão JC. Impact of ageing and drug consumption on oral health. Gerodontology. 2009;26(4):297-301.
9. Murray Thomson W, Chalmers JM, John Spencer A, Slade GD, Carter KD. A longitudinal study of medication exposure and xerostomia among older people. Gerodontology. 2006;23(4):205–13.

10. Nykänen I, Lönnroos E, Kautiainen H, Sulkava R, Hartikainen S. Nutritional screening in a population-based cohort of community-dwelling older people. Eur J Public Health. 2013;23(3):405–9.

11. Furuta M, Komiya-Nonaka M, Akifusa S, Shimazaki Y, Adachi M, Kinoshita T, et al. Interrelationship of oral health status, swallowing function, nutritional status, and cognitive ability with activities of daily living in Japanese elderly people receiving home care services due to physical disabilities. Community Dent Oral Epidemiol. 2013;41(2):173–81.

12. Savoca MR, Arcury TA, Leng X, Chen H, Bell RA, Anderson AM, et al. Impact of denture usage patterns on dietary quality and food avoidance among older adults. J Nutr Gerontol Geriatr. 2011;30(1):86–102.

13. Algra Y, Haverkort E, Kok W, van Etten-Jamaludin F, van Schoot L, Hollaar V, et al. The Association between Malnutrition and Oral Health in Older People: A Systematic Review. Nutrients. 2021;13(10):3584.

14. Toniazzo MP, de Amorim P S, Muniz FWMG, Weidlich P. Relationship of nutritional status and oral health in elderly: Systematic review with meta-analysis. Clin Nutr Edinb Scotl. 2018;37(3):824–30.

15. Rosa RW, Samot J, Helmer C, Pourtau G, Dupuis V, Fricain J-C, et al. Important oral care needs of older French people: A cross-sectional study. Rev Epidemiol Sante Publique. 2020;68(2):83–90.

16. Dartigues JF, Gagnon M, Barberger-Gateau P, Letenneur L, Commenges D, Sauvel C, Michel P, Salamon R. The Paquid epidemiological program on brain ageing. Neuroepidemiology. 1992;11(Suppl 1):14–8.

17. World Health Organization. Oral Health Surveys Basic Methods. Fifth Edition [Internet]. Fifth. 2013. Disponible sur: http://www.icd.org/content/publications/WHO-Oral-Health-Surveys-Basic-Methods-5th-Edition-2013.pdf. Accessed 10 October 2021

18. Berner YN. Assessment tools for nutritional status in the elderly. Isr Med Assoc J. 2003;5(5):365–7.

19. Hugonot-Diener L. Présentation du MNA ou MINI nutritional assessmentTM, Mini Nutritional Assessment (MNA) tool for screening and monitoring malnutrition. Gérontologie Société. 2010;134(3):133–41.

20. Tsakos G, Marcenes W, Sheiham A. The relationship between clinical dental status and oral impacts in an elderly population. Oral Health Prev Dent. 2004;2(3):211–20.

21. Thomson WM, Chalmers JM, Spencer AJ, Williams SM. The Xerostomia Inventory: a multi-item approach to measuring dry mouth. Community Dent Health. 1999;16(1):12–7.

22. Hummel SK, Wilson MA, Marker VA, Nunn ME. Quality of removable partial dentures worn by the adult U.S. population. J Prosthet Dent. 2002;88(1):37–43.

23. Koo TK, Li MY. A Guideline of Selecting and Reporting Intraclass Correlation Coefficients for Reliability Research. J Chiropr Med. 2016;15(2):155–63.

24. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. [Internet]. Report No.: Fifth Edition. Disponible sur: https://dsm.psychiatryonline.org/doi/book/https://doi.org/10.1176/appi books.9780890425596. Accessed 10 October 2021

25. Leij-Halfwerk S, Verwijs MH, van Houdt S, Borkent JW, Guaitoli PR, Pelgrim T, et al. Prevalence of protein-energy malnutrition risk in European older adults in community, residential and hospital settings, according to 22 malnutrition screening tools validated for use in adults ≥65 years: A systematic review and meta-analysis. Maturitas. 2019;126:80–9.

26. López R, Smith PC, Göstemeyer G, Schwendicke F. Ageing, dental caries and periodontal diseases. J Clin Periodontol. 2017;44(Suppl 18):S145–52.

27. Kiesswetter E, Hengeveld LM, Keijser BJ, Volkert D, Visser M. Oral health determinants of incident malnutrition in community-dwelling older adults. J Dent. 2019;85:73–80.

28. Nihtilä A, Tuuliainen E, Komulainen K, Nykänen I, Hartikainen S, Tiihonen M, et al. The combined effect of individually tailored xerostomia and nutritional interventions on dry mouth among nutritionally compromised old home care clients. Gerodontology. 2019;36(3):244–50.

29. Moynihan P, Thomason M, Walls A, Gray-Donald K, Morais JA, Ghanem H, et al. Researching the impact of oral health on diet and nutritional status: methodological issues. J Dent. 2009;37(4):237–49.

30. McKenna G, Allen PF, O'Mahony D, Cronin M, DaMata C, Woods N. Impact of tooth replacement on the nutritional status of partially dentate elders. Clin Oral Invest. 2015;19(8):1991–8.

## Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Ready to submit your research? Choose BMC and benefit from:

* fast, convenient online submission

* thorough peer review by experienced researchers in your field

* rapid publication on acceptance

* support for research data, including large and complex data types

* gold Open Access which fosters wider collaboration and increased citations

* maximum visibility for your research: over 100M website views per year

At BMC, research is always in progress.

Learn more biomedcentral.com/submissions

BMC