1 Volume 21 2022 e226709 Original Research Braz J Oral Sci. 2022;21:e226709http://dx.doi.org/10.20396/bjos.v21i00.8666709 1 Department of Stomatology, Health Sciences Center, Federal University of Santa Maria, Santa Maria, RS, Brazil. 2 Department of Oral and Maxillofacial Rehabilitation, University of Talca, Talca, Chile. 3 Paulista University (UNIP), Campinas, SP, Brazil. 4 Department of Gerontology, University of Campinas, Campinas, SP, Brazil. 5 Department of Health Sciences and Pediatric Dentistry, Piracicaba Dental School, University of Campinas, Piracicaba, SP, Brazil. Corresponding author: Maria da Luz Rosário de Sousa, Department of Health Sciences and Pediatric Dentistry, Piracicaba Dental School, State University of Campinas, Av. Limeira, 901 - Areião, Piracicaba - SP, 13414-018, +55 19 2106-5209. E-mail: luzsousa@fop.unicamp.br Editor: Altair A. Del Bel Cury Received: August 18, 2021 Accepted: January 20, 2022 Functional dentition and associated factors: the evaluation of three indicators Luísa Helena do Nascimento Tôrres1 , María Jesús Arenas-Márquez2 , Débora Dias da Silva3, Roberta Barros de Held4, Talita Bonato de Almeida5 , Anita Liberalesso Neri4 , Maria da Luz Rosário de Sousa5,* Studying the different indicators of functional dentition classification can contribute to the understanding of the associated factors, and thus help in the definition of strategies associated with oral health care. This approach has been little explored in the literature, especially when considering the older age group. Aim: The aim of this study is to evaluate the factors associated with three distinct functional dentition classification. Methods: Cross- sectional exploratory study using secondary data from the Frailty in Older Brazilians (FIBRA) Project of 876 older adults living in Campinas, Brazil. The indicators of dental function assessed was number of natural teeth present, occluding pairs of teeth and the Eichner index, which were verified by trained dentists, following the World Health Organization criteria for epidemiological studies in oral health. The explanatory variable assessed was the self- perception of oral health-related quality of life measured by the Geriatric Oral Health Assessment Index (GOHAI) and its dimensions. It was also collected sociodemographic information such as age, gender, race/ethnicity, schooling, family income, smoking behavior and frailty status. The association was verified through Poisson regressions for number of teeth and pairs of teeth in occlusion and multinomial regression for the Eichner index, adjusted by sociodemographic and health variables. Results: Lower prevalence of participants with less than 21 teeth who negatively perceived GOHAI´s pain and discomfort dimension and higher prevalence of having less teeth among the ones that negatively perceived GOHAI´s physical and functional dimensions. No association was found between the perception of quality of life and occlusion pairs of teeth and the Eichner Index. Conclusion: Two out of three indicators assessed were associated with quality of life. Therefore, it is important to select sensitive indicators to be able to identify and better comprehend this relationship. Keywords: Aged. Dentition. Quality of life. https://orcid.org/0000-0003-0740-2785 https://orcid.org/0000-0002-5017-4303 https://orcid.org/0000-0002-0533-7126 https://orcid.org/0000-0002-6833-7668 https://orcid.org/0000-0002-0346-5060 2 Tôrres et al. Braz J Oral Sci. 2022;21:e226709 Introduction Oral health tends to decline with aging. Cumulative and progressive changes through- out life can result in tooth loss, which impairs the functionality of the dentition1. The reduction in the number of teeth can lead to a loss of masticatory efficiency, affecting nutrition2, communication, self-esteem, general well-being3, and even being associ- ated with a higher risk of morbidity and mortality4. Few studies evaluate the relation between functional condition of dentition and qual- ity of life5, and there are even less about older populations. This is the age group with more sequelae in the dentition1. The multidimensional impairment of tooth loss can affect and be affected by quality of life, and thus evaluating the different types of clas- sification can contribute to the understanding of associated factors and especially the quality of life evaluated globally and through different dimensions, such as pain/ discomfort, physical and psychological aspects. This relationship is frequently stud- ied with a focus on the number of teeth1, but this impact may vary depending on the degree of the dentition functionality, as in the case of the Eichner indicator that is still barely used in the literature. As seen in a recent systematic review6, which verified the association between oral health factors associated with oral health-related quality of life (OHQoL) in people aged 65 or more. In addition, the study found that the literature shows a consensus about the positive association between the number of natural teeth and occluding pairs of teeth with OHQoL. One of the factors that hinder this relationship is the lack of consensus on the func- tional dentition definition5. The World Health Organization (WHO), FDI World Dental Federation (FDI) and International Association for Dental Research (IADR) have jointly established that to have a functional dentition, a person must retain at least 21 nat- ural teeth7. This definition is widely used in research8; however, it does not consider the quantity and location of occlusal contacts. The evaluation of occlusal contacts seems to be more descriptive and discriminatory in determining the functional condi- tion of the dentition9,10. However, studies in the literature are heterogeneous for study designs, populations, assessments of the measurements, and outcome tools6. This makes the evidence not conclusive and insufficient to determine the extent to which the functional condition of the dentition affects the quality of life of older adults. Considering the aforementioned, the functional condition of the dentition was ver- ified using three clinical indicators, aiming to evaluate the factors associated with each type of functional dentition classification focusing on the association with oral health-related quality of life. Material and Methods Study design and participants The data employed in the present cross-sectional study were taken from the “Fragil- idade em Idosos Brasileiros” – FIBRA (Frailty in Older Brazilians) study, conducted in 2008-2009. The FIBRA survey was a population-based, multicenter study designed to investigate conditions of frailty regarding health, sociodemographic, psychosocial, 3 Tôrres et al. Braz J Oral Sci. 2022;21:e226709 and functionality variables in older people of the community. Methodological details have been previously published11. The minimum sample size was estimated at 601 elderly people living in the commu- nity (Campinas – SP). For this calculation, the formula and parameters were used as described: n={z2 x [p x q / e2]} (formula for calculating sample size, without cor- rection for finite populations); z=1.96 (95% significance level); p=q=0.50 (maximum confidence values to estimate prevalence in sample studies); e=4% (sampling error margin). A total of 90 census sectors were drawn, of which 88 sectors were part of the sample of 900 elderly people, totaling an average of 10.2 elderly people per sector. The sample was probabilistic by conglomerates, with the urban census sectors as the sampling unit. The number of census tracts was defined by dividing the number of existing urban census tracts by the desired number of elderly people. The recruit- ers received the map of each census sector and visited all the households to recruit as well as to identify those in which there were one or more elderly residents and interviewed those who met the inclusion criteria. In addition, they scheduled sessions for the next week with the elderly who agreed to participate. This sample, representative of the older population of Campinas, Brazil, included participants aged 65 or over who had complete data for the dependent variables “functionality of dentition”, as well as for the independent variables: “quality of life” (explanatory variable), and “sociodemographic/health conditions” (control variables). All procedures were approved by the Ethics Committee of the School of Medical Sci- ences of the University of Campinas (process nº 208/2007). Functionality of dentition Three clinical indicators were evaluated, through dental examinations performed by three trained dentists, with a gold-standard examiner with experience on data collec- tion following the WHO criteria for epidemiological studies in oral health12. Individuals using dentures were asked to remove them. The variable occluding pairs of teeth was constructed based on the natural teeth present. Measurements: • Number of natural teeth present: Categorized into up to 20 teeth (impaired) and 21 or more teeth (functional), according to the global goals for oral health 2020, proposed by WHO, FDI and IADR7. • Occluding pairs of teeth: Categorized according to the average number of occlu- sive teeth estimated in this research: up to 2 pairs and 3 or more pairs. • Eichner Index: Posterior occlusal contacts were classified into four support re- gions (two molars and two premolars), and three categories were determined: “A” occlusal contacts in four posterior regions; “B” contacts in up to three posterior regions or only in the anterior area; and “C” without occlusal contacts13. Oral Health-related quality of life (OHRQol) We used the Geriatric Oral Health Assessment Index (GOHAI) validated in Brazil14, designed to assess the perception of oral health problems that impact quality of life in older adults15. The instrument consists of 12 questions, whose answers “always”, “sometimes”, and “never” were weighted on a scale of 1 to 3 points in ascending 4 Tôrres et al. Braz J Oral Sci. 2022;21:e226709 order, from the more negative condition to the more positive one, according to the context of the question. The higher the sum of the scores, more positive the evalua- tion is, therefore, lower perception of the impact of oral health on quality of life. The questionnaire was analyzed globally and according to dimensions of oral health problems. Two categories were dichotomized based on a previous study16: positive perception that corresponded to a high score (in the global index greater than 34 points, and in the dimensions: physical/functional greater than 10 points, psychoso- cial/psychological 15 points, and pain/discomfort 9 points), and negative perception, corresponding to a moderate/low score (lower than the scores already indicated as high for the global index and for each dimension). Sociodemographic/behavior/health conditions Sociodemographic data were collected: age, gender, race/color dichotomized according to the sample distribution in “Caucasians” and “non-Caucasians” (cat- egory that included those who declared themselves as “black”, “mulato/caboclo/ pardo”, “Indigenous” or “yellow/oriental”), literacy, schooling dichotomized in “up to three years of study” and “four or more years of study”, if retired, family income according to the minimum wage (MW) in 2008 equivalent to R$ 415.00/US $ 231, being dichotomized into “up to two MW” and “three or more MW”, and possession of residence (owner or not). Data on self-reported smoking of older adults were also collected. Frailty according to the phenotype of Fried et al.17 (2001), whose evaluation details were previously published15. Regarding oral health, access to dental services (“insurance/private” or “public”) and self-assessed oral health dichotomized as “positive” (when the older person assessed it as “excellent” or “good”) and “negative” (when the evaluation was “regular” or “bad”). Statistical analysis Associations between each dentition functionality indicator and independent vari- ables were verified using the chi-square and Fisher’s exact tests. Multivariate models were constructed with the variables that showed an association of p <0.25 in the bivariate analyzes, performing Poisson regressions for number of teeth (model 1) and pairs of teeth in occlusion (model 2); and multinomial regression for the Eichner index (model 3). In the models, variables with a statistical significance of p <0.05 were presented, showing prevalence and odds ratios with 95% confidence intervals. It was used the backward stepwise method in this exploratory study on which the variables considered in the analysis were based on the p value and the epidemiological rele- vance on the association. Results Research participants Of the 900 participants in the FIBRA study, 876 had complete data to be included in the analysis; their characteristics are described in Table 1. The mean age of the vol- 5 Tôrres et al. Braz J Oral Sci. 2022;21:e226709 unteers was 72.78 (± 5.8) years, with a predominance of women (69.3%), caucasians (70.9%), four years or more of schooling (58.7%), and a family income above two min- imum wages (71.8%). Most of them assessed positively both their oral health (72.4%) and their quality of life in relation to oral health (69.8% - global GOHAI). GOHAI ranged from 12 to 36 points. Functional dentition condition Only 14.1% of the older adults had 21 or more teeth, 25.3% had three or more occlud- ing pairs of teeth and 71.3% had no occlusal contact (Eichner C index), with a low prevalence of functional dentition (Table 1). Table 1. Characteristics of the participants according to the studied variables (n= 876). Variables n (%) Gender Man 276 (30.7) Woman 624 (69.3) Race/Color Caucasian 636 (70.9) Non-Caucasian 261 (29.1) Literate No 196 (21.9) Yes 699 (78.1) Schooling 4 or more years 371 (41.3) Up to 3 years 528 (58.7) Retired No 261 (29.2) Yes 634 (70.8) Family Income* Up to 2 MW 221 (28.2) 3 or more MW 562 (71.8) Home-owneship No 162 (18.0) Yes 738 (82.0) Smoking No 612 (88.8) Yes 77 (11.2) Frailty Not frail 359 (39.9) Pre-frail 469 (52.1) Continue 6 Tôrres et al. Braz J Oral Sci. 2022;21:e226709 Continuation Frail 72 (8) Use of Dental Service Insurance/private 440 (67.7) Public 210 (32.3) Oral Health Self-Assessment Negative 186 (27.6) Positive 487 (72.4) GOHAI - Global Index Negative (12 to 33 points) 265 (30.2) Positive (34 to 36 points) 612 (69.8) GOHAI – Physical / functional dimension Negative (4 to 9 points) 108 (12.3) Positive (10 to 12 points) 769 (87.7) GOHAI – Psychological /psychosocial dimension Negative (5 to 14 points) 320 (36.5) Positive (15 points) 557 (63.5) GOHAI – Pain/ discomfort dimension Negative (3 to 8 points) 236 (26.9) Positive (9 points) 641 (73.1) Number of teeth Up to 20 teeth 753 (85.9) 21 or more teeth 124 (14.1) Paired teeth in occlusion Up to 2 pairs 655 (74.7) 3 or more pairs 222 (25.3) Eichner Index A (occlusal contact in 4 posterior regions) 68 (7.7) B (occlusal contact in up to 3 posterior regions/ anterior only) 184 (21) C (without occlusal contact) 626 (71.3) GOHAI, Geriatric Oral Health Assessment Index (positive perception: high score; negative perception: moderate/low score). *MW, minimum wage (in 2008 2MW = R$ 830.00; on average US$ 462). Perception of problems associated with functional condition of dentition In Figure 1, the oral health problems that impact on quality of life (GOHAI) associated with the studied clinical conditions stood out. Regardless of the functional condition of the dentition, most older adults estimated that they had no problems that limited their diet (type and quantity), or speech, dissatisfaction with the smile, or discomfort eating in front of other people. The number of older adults with impaired dentition that indicated problems in chewing was higher. 7 Tôrres et al. Braz J Oral Sci. 2022;21:e226709 Figure 1. Frequency of response of older people to the GOHAI questions according to the functional condition of the dentition. The bar at the end of the figure symbolizes the range of colors that each category could acquire according to the number of older people who answered within it. It ranged from 0 individuals (white) increasing in intensity to black (876 responses), which is the maximum number of participants in this study. The categories of the Eichner Index mean: A, occlusal contact in 4 posterior regions; B, occlusal contact in up to 3 posterior regions/anterior only; and C, without occlusal contact. *p <0.05 for chi-square and Fisher’s exact tests. Perception of quality of life with different degrees of functionality in dentition Regarding the presence of teeth and pairs of teeth in occlusion, Table 2 showed the profile of older adults impaired dentition: women, non-caucasian, with low education and low family income, who negatively perceived their quality of life due to problems in the physical/functional dimension. However, older adults with functional dentition negatively perceived the pain/discomfort dimension. As for the Eichner index, Table 3 presented profiles of older people according to the number and location of occlusal contacts. Individuals with occlusal contact in all pos- terior regions (Eichner A) had higher education and higher family income. This charac- teristic is shared with those with occlusal contact in up to three posterior regions or only anterior (Eichner B). In addition, the latter group assessed their oral health negatively. No association was found between the perception of quality of life and these profiles. 8 Tôrres et al. Braz J Oral Sci. 2022;21:e226709 Table 2. Poisson regression models with variables associated with the number of teeth (Model No. 1) and pairs of teeth in occlusion (Model No. 2). Variables Model No 1 Model No 2 Number of teeth* (up to 20 teeth) Paired teeth in occlusion** (up to 2 pairs of teeth in occlusion) Crude PR (95% CI) p Adjusted PR (95% CI) p Crude PR (95% CI) p Adjusted PR (95% CI) p Schooling Up to 3 Years (Ref. 4 or more years) 1.17 (1.11-1.23) < 0.001 1.12 (1.07-1.18) < 0.001 1.40 (1.26-1.55) < 0.0001 1.28 (1.19-1.39) < 0.0001 Family Income Up to 2 MW (Ref. 3 or more MW) 1.12 (1.06-1.18) < 0.001 1.07 (1.02-1.12) 0.004 1.29 (1.17-1.43) < 0.0001 1.15 (1.07-1.24) < 0.0001 Gender Man (Ref. Female) 0.91 (0.85-0.97) 0.008 0.91 (0.85-0.97) 0.01 0.83 (0.73-0.95) 0.001 0.87 (0.79-0.96) 0.02 Race/Color Non-Caucasian (Ref. caucasian) 0.87 (0.83-0.91) < 0.001 1.10 (1.05-1.16) < 0.001 GOHAI Physical/functional dimension Negative perception (Ref. Positive) 1.12 (1.07-1.18) < 0.001 1.12 (1.05-1.20) < 0.001 GOHAI Pain/discomfort dimension Negative perception (Ref. Positive) 0.91 (0.85-0.98) 0.014 0.91 (0.84-0.98) 0.01 *Reference category: 21 or more teeth ** Reference category: 3 or more pairs PR, Prevalence Ratio; CI, confidence interval; SM, Minimum wage. Table 3. Multinomial regression with variables associated with the Eichner Index * (Model No. 3). Variables A (occlusion in 4 posterior regions) B (occlusion in up to 3 posterior regions/anterior only) Crude OR (95% CI) p Adjusted OR (95% CI) p Crude OR (95% CI) p Adjusted OR (95% CI) p Schooling Up to 3 Years (Ref. 4 years or more) 0.17 (0.09-0.35) < 0.001 0.27 (0.12-0.60) 0.001 0.35 (0.24-0.51) < 0.001 0.35 (0.21-0.56) < 0.001 Family Income Up to 2 MW (Ref. 3 or more MW 0.13 (0.04-0.38) < 0.001 0.18 (0.05-0.61) 0.005 0.39 (0.25-0.61) <0.001 0.44 (0.24-0.78) 0.005 Gender Man (Ref. Female) 1.20 (0.70-2.06) 0.51 1.32 (0.70-2.49) 0.38 2.01 (1.43-2.83) < 0.001 1.97 (1.28-3.03) 0.002 Oral Health Self-Assessment Negative (Ref. Positive) 0.64 (0.32-1.26) 0.20 0.69 (0.33-1.44) 0.32 1.56 (1.05-2.32) 0.027 1.57 (1.01-2.48) 0.04 *Reference category: C (without occlusion) OR, Odds Ratio; CI, Confidence Interval; MW, minimum wage. 9 Tôrres et al. Braz J Oral Sci. 2022;21:e226709 Discussion This research contributes to broaden the understanding of factors that affect oral health on older adults, with a still little explored approach in the literature. The asso- ciations found reveal two realities: older adults who perceive physical and func- tional problems have impaired dentition; and, surprisingly, those who do have func- tional dentition perceive problems related to pain and discomfort, probably because of the presence of unhealthy teeth. These two conditions (physical/functional and pain/discomfort) seem to have a negative impact on quality of life. In general, the study shows low prevalence of functional dentition. Similar information was found in the literature18,19. Although there has been a worldwide trend in the last few decades to preserve more teeth in aging20, this reality will probably occur in Brazil by 205021. The causes are multifactorial; on the one hand, the current generation of older adults has belatedly benefited from the preventive public policies implemented in recent years21, added to the limited use of dental services, and the legacy of a care model in which mutilating practices prevailed22. Even with the low prevalence of functional dentition, most older people have a pos- itive perception of their oral health and overall quality of life, showing a difference between self-perception and real condition, also seen in other studies16,22. This finding can be explained because older adults are more resilient related to oral health10 and they adapt to oral conditions, devaluing the impact of diseases because they assume that it is an inevitable consequence of aging22. For this reason, evaluating quality of life from a global point of view could mask the identification of specific functions that harm older adults. And therefore, each dimen- sion in particular was analyzed, finding a negative impact on physical/functional and pain/discomfort dimensions when older adult has less than 20 teeth. The physical/functional dimension of GOHAI assess several factors14, including chewing ability, which was affected in most older people without functional dentition. This finding seems to be expected and confirmed in previous studies23,24. Many stud- ies prove that older people with impaired dentition are more likely to have masticatory problems8,23 and to perceive them as negative for their quality of life10,24 emphasizing the need to maintain a functional dentition. Precarious condition of the remaining teeth can explain the pain and discomfort that affect older people with functional dentition, as already observed in a similar study25 endorsed by world statistics that indicate an increase in oral diseases and need for treatment not attended due to reduction of tooth loss20. Therefore, this is probably the cause of negative perception in this area. The profiles also reveal that they come from different segments of society. Women, non-caucasians, with low educational level, and whose family group lives in poor economic conditions characterize the profile of older adults with impaired den- tition. As the oral condition improves, the profile is associated with higher educa- tion and income. This social gradient was also observed for tooth loss21. Conse- quently, the functional condition of dentition could be considered an indicator of social inequality. 10 Tôrres et al. Braz J Oral Sci. 2022;21:e226709 The low socioeconomic level is related to the lack of use of dental services21,26, lim- ited information on prevention habits26,27, and difficulty in recognizing a health need28. Despite the efforts to reduce social inequalities, they still persist among older adults28 and have an impact on the observed oral condition. Gender seems to have a different effect according to the outcome evaluated. Being men was associated with a lower prevalence of having less teeth and less occluding pairs of teeth but a higher prevalence of having occlusal contact in up to three poste- rior regions or only in anterior region (Eichner B). Women tend to use more regularly the oral health services and consequently are more susceptible to have their teeth extracted as a result of overtreatment29. As a differential of other studies, the functional condition of dentition was assessed considering three clinical indicators8, and as for quality of life it was used two indi- cators, one subjective (a self-perception single question) and another objective (The GOHAI instrument and its dimensions). The number of teeth was the indicator of dentition functionality that identified more associated factors, including quality of life, even though more precise measures such as occluding pairs of teeth and Eich- ner index were adopted8. On the other hand, the Eichner index characterized pro- files in older adults, which to our understanding, have not yet been described in Bra- zil using this instrument, showing a differential of this study. Hence the importance of this study in expanding the understanding of associated factors according to the indicator used. As a limitation, we recognize the lack of oral health variables to check the condition of the remaining teeth and the use of prosthesis, that could confirm the hypothesis of discussion about the association of functional dentition and the perception of pain/discomfort. As it is an exploratory cross-sectional study, it advances in recog- nizing the variability of associated factors according to the selected indicator. Finally, we emphasize that despite the worldwide trend to preserve more teeth throughout life, older Brazilians still do not retain a number of teeth or adequate occlu- sal contacts to have a functional dentition and they perceive the negative impact of this condition. This reality reveals the need for preventive and therapeutic measures to maintain a healthy and functional dentition throughout life. Two out of the three indicators assessed in this study were associated with quality of life. Therefore, it is important to select sensitive indicators to be able to identify and better comprehend the relationship between a functional dentition and quality of life, especially in this age group that has great tooth loss. Acknowledgments The authors thank Espaço da Escrita – Pró-Reitoria de Pesquisa – UNICAMP – for the language services provided. Funding sources: National Council for Scientific and Technological Development (CNPq) – 555082/2006-7 and São Paulo Research Foundation (FAPESP) - No. 2008/03919-7. 11 Tôrres et al. Braz J Oral Sci. 2022;21:e226709 Data avaliability The datasets related to this article belong to the FIBRA research group and will be available upon request from the author responsible for the project. Data availability Datasets related to this article will be available upon request to the corresponding author. Conflict of Interest None Author contribution Conceptualization: DDS, MLRS. Methodology: RBH, LHNT, DDS, ALN, MLRS. Formal analysis: LHNT, DDS, MLRS. Investigation: RBH, DDS. Resources: ALN. Data curation: DDS. Writing—original draft preparation: RBH, LHNT, DDS. Writing—review and editing: RBH, LHNT, MJAM, TBA, DDS, ALN, MLRS. Supervision: DDS, ALN, MLRS. Project administration: DDS, ALN, MLRS. Funding acquisition: DDS, ALN. All authors have read and agreed to the published version of the manuscript. References 1. Müller F, Shimazaki Y, Kahabuka F, Schimmel M. Oral health for an ageing population: the importance of a natural dentition in older adults. Int Dent J. 2017 Sep;67 Suppl 2:7-13. doi: 10.1111/idj.12329. 2. Gil-Montoya JA, Mello AL, Barrios R, Gonzalez-Moles MA, Bravo M. Oral health in the elderly patient and its impact on general well-being: a nonsystematic review. Clin Interv Aging. 2015 Feb;10:461-7. doi: 10.2147/CIA.S54630. 3. Bidinotto AB, Santos CM, Torres LH, Sousa MD, Hugo FN, Hilgert JB. 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