Oral Health Promotion among Individuals with Intellectual Disabilities: A Systematic Review

Abstract People with disabilities experience inferior health and poor access to good quality health services as compared with the general population. Optimum oral health is associated with improvement in the quality of life in such patients. As oral diseases are largely preventable, good oral health education can have a positive impact on individuals with disabilities. So, the aim of the study was to review the effectiveness of oral health promotion among individuals with intellectual disabilities (IDs). Seven electronic databases were searched using keywords like intellectual disability/mental retardation/learning disability AND dental health education/health promotion. All records that were identified electronically from this search were subjected to a preliminary review to identify eligible papers. Identified studies were grouped into oral health promotion directed at individuals with IDs, and those aimed at caregivers of people with IDs. Interpretation of the outcomes included the effects on oral health knowledge, attitudes, and behaviors (either observed or self-reported). Eventually, 16 studies were included in the review including five studies that were randomized controlled trials, while the remaining 11 studies were pre-post single group oral health promotion studies. Critical appraisal of each study was conducted with the 21-item criteria by Kay and Locker (1997) to provide a numerical quantification and ranking of the evidence. Positive changes in the behaviors and attitudes were observed, while other studies reported a considerable improvement in the knowledge of caregivers for oral healthcare of individuals with IDs. However, such activities need to be done over a long period of time with constant monitoring.


Introduction
People with disabilities are entitled to good quality of life including their good oral health.However, it has been observed that people with disabilities may experience inferior health and poorer access to good-quality health services as compared with the general population. 1,2Globally, the burden of oral diseases is large, especially among individuals with disabilities as they already suffer from the impact of the disability itself. 3he presence of the disability itself increases the individual's expenditure on many sectors such as health, education, and social services. 4Oral health problems include a range of diseases and conditions that involve dental caries, periodontal diseases, oral cancer, noncarious tooth surface loss, and oral mucosal diseases. 5Although oral diseases are largely behavioral in origin and notionally preventable, they remain a significant public health challenge in many developed as well as developing countries. 6ntellectual disability (ID) is a generalized neurodevelopmental disorder characterized by significant impairments in mental capacity and adaptive behaviors (conceptual, social, and practical skills). 7Individuals with IDs constitute a considerable segment of the population that might increase with time because of the higher disease survival rates after adequate medical care. 8,9People with IDs, most often, lack the understanding of daily tasks like personal hygiene 6 and proper oral healthcare. 10Moreover, the barriers to good oral health for individuals with IDs also include low awareness level among caregivers, 11 and their inadequate training. 12The role of caregivers in providing oral healthcare for individuals they support is very crucial and there is a need to promote regular oral hygiene practices. 13][19] However, there is a lack of consensus among these studies aimed at evaluating the effectiveness of oral health promotion among individuals with IDs.This is mainly because of the variety of interventions used and the direct target population studied.Therefore, there is a need to compile the findings on such studies and summarize the effectiveness of implemented interventions.Hence, this study aimed to assess the effectiveness of oral health promotion activities/interventions for desired oral health outcomes conducted among individuals with IDs as well as their caregivers by reviewing the available literature.

Methods Search Strategy
Seven electronic databases [Ovid (which includes three databases: Embase, MEDLINE, PsychINFO), Web of Knowledge, CINAHL, The Cochrane Library, and Scopus] were searched using the following keywords: (ID/mental retardation/mental handicap/ learning disability) AND (dental/oral) AND (dental health education/ health promotion/ oral health/ dental hygiene/preventive dentistry/behavior training).
All records that were electronically identified from this search were subjected to a preliminary review to identify eligible papers by two independent authors.In case of any discrepancy between the two authors, a third author was consulted for general consensus.Reports published more than once from the same study were excluded by reconfirmation of any duplication of reports.The term ID has been previously used as mental retardation or mental handicap.However, such terminology is discriminatory and as such ID is a more accepted term used. 20The term ID is also used concomitantly with the term "learning disability," like in the United Kingdom which sometimes confuses with the term "learning difficulty"; hence, we preferred to use "Intellectual disability" consistently for terms learning disability, mental handicap, mental retardation, etc. that have been used historically.►Table 1 explains the Population, Intervention, Comparison and Outcome of the referenced studies in accordance with parameters for systematic reviews. 21The reference list of each retrieved paper was also reviewed.This was done to avoid duplication and to find out any study that might not have been found with the search strategy.An overall 90 papers were retrieved as shown in ►Fig. 1 that was done according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines 2020. 22eaving aside individuals with mild IDs, individuals with moderate-to-severe IDs are not able to do their routine oral hygiene procedures by themselves, and it has to be usually done by their caregivers.Therefore, it is important to train the caregivers for proper oral healthcare of individual with IDs.Hence, this study was divided into looking at oral health promotion in individuals with ID and by their caregivers.Interpretation of the intervention outcomes in this review included both clinical outcomes and the effects on oral health knowledge, attitudes, and behaviors (either observed or selfreported).For each outcome measure, the findings were grouped according to the particular outcome measured, such as plaque, gingival health, oral hygiene as well as knowledge, attitude, and behavior of individuals with IDs.Inclusion/selection criteria has been mentioned in ►Table 2.

Focused Research Question
Are oral health promotion activities/interventions either directed at individuals with IDs or at their caregivers effective in improvement of desired oral health outcomes?

Validity Assessment and Data Extraction
From each study included, data on study details (year study began, place/country where study was conducted, duration of the study), type of study, baseline characteristics of participants (number included, age [mean/range], and settings where participants were recruited), characteristics of the intervention and its follow-up duration, and finally the results of each study were extracted.No date limit was set for the studies.The studies found were classified according to the target of the study population (individuals with IDs and/or their caregivers).A description of each study published in the context of the focused research question that is eventually selected for this review is provided in ►Tables 3, 4, and 5. Critical appraisal of each study was conducted with the 21item criteria to provide a numerical quantification and ranking of the evidence as proposed by Kay and Locker in 1997. 23The quality score was ascertained by calculating the number of affirmative answers to the 21 items.A score of 21 indicates the highest quality of evidence and a score of 0 the weakest quality of evidence, as is represented in ►Table 3.However, it should be noted that Kay and Locker assessment criteria was developed mainly to assess traditional randomized control trials, while the majority of retrieved papers were a single-group pre-and post-test studies; therefore, the overall scores of obtained studies were below average.It would be better if more recent/updated checklist criteria are available for quality assessments so that the low scores of quality assessment do not necessarily mean a poor-quality study.
There were two independent authors who read all the articles to find the suitability to be included in the review.A master list for each search engine was made of all retrieved articles and finally selected article list.In case of any discrepancy between the two independent authors, a third author was consulted and after mutual consensus and discussion a decision was arrived at.

Results
The combined electronic searches revealed 850 papers from the seven databases.Of the 179 papers retrieved, after a preliminary search from Ovid, which include the three databases of Embase, MEDLINE, PsychINFO, only 11 papers were identified as potentially eligible.From the Web of Knowledge search, 265 papers were retrieved, and, using the inclusion criteria, only 32 papers appeared to be potentially relevant.Using CINAHL, 149 papers were retrieved after the preliminary search, and only 7 papers primarily met the inclusion criteria.In the Cochrane Library, the preliminary search revealed 78 (26 Cochrane reviews and 52 Trials), although only 21 seemed to be potentially relevant.And finally, a search on the Scopus database resulted in 179 papers, 20 of which seemed to be of potential relevance to the focused research question.Finally, only 16 studies qualified after application of the selection criteria as mentioned in ►Table 2 and the study selection process represented in the PRISMA flowchart as ►Fig. 1.
Studies were conducted mainly at schools or communitybased residential services and nursing homes.The sample size of the target study populations varied considerably from 20 to 382.The follow-up period also varied widely across studies with some having a follow-up period of just a few weeks, while the majority had a follow-up period of 2 years.The results of the search and further discussion is classified based on the target population of the planned intervention.Therefore, studies were grouped into either oral health promotion interventions among individuals with IDs, or oral health promotion interventions among caregivers of individuals with IDs.

Oral Health Promotion Studies among Individuals with IDs
The search revealed seven studies that aimed to improve the oral health of individuals with IDs by directing their oral health promotion with them directly 24,25,30,34,[36][37][38] as is represented in ►Table 4. Almost all interventions were educational in nature, and some of them included training programs (e.g., supervised tooth-brushing techniques).Two of them were randomized controlled trials 24,25 and the remaining studies 30,34,[36][37][38] were pre-and post-test single-group interventions.In some studies, where the main interventions were directed to individuals with IDs, education of the caregivers was also considered as a part of the intervention.Furthermore, various outcome measures were used to assess the level of dental plaque that made the ability to make comparisons across studies.Several studies compared the effectiveness of powered toothbrushes compared with manual toothbrushes.Comparisons were made of different types of toothbrushes and employed different methods of assessing dental plaque.

Studies Related to Plaque, Gingival Health, and Oral Hygiene
All included studies, except by Altabet et al 24 assessed the interventions' outcomes by measuring the oral health status of individuals with IDs; however, different measures were used across the studies (e.g., simplified debris index, simplified oral hygiene index, plaque index, or gingival index).The findings of all the intervention studies in general revealed an improvement in the oral hygiene of participants, but the long-term key to success is the maintenance and continuous delivery of such programs.

Studies Related to Knowledge, Attitudes, and Behaviors
None of the studies considered measuring changes in knowledge, attitudes, and behaviors as a main outcome measure of interventions directed to individuals with IDs, and while some authors reported in their conclusions that their

Oral Health Promotion Studies among Caregivers of Individuals with IDs
Nine studies [26][27][28][29][31][32][33]35,39 were found in the literature about oral health promotion for caregivers of individuals with IDs as represented in ►Table 5. Three of the reported studies were randomized controlled trials, [26][27][28] and the remaining were single groups pre-and post-intervention. All intervetions were educational in nature, and were aimed at training the caregivers and improving their knowledge of the proper toothbrushing and flossing techniques.In Glassman and Miller's 33 study, the researchers tried to implement an indirect training program in which they trained the caregivers and measured the ultimate outcome on the individuals with IDs.Only one study 27 reported a change in the institution's policy that was accompanied by staff training, but no details about the implemented policy were mentioned.

Studies Related to Plaque, Gingival Health, and Oral Hygiene
Some studies evaluated the effectiveness of the interventions' programs by measuring the oral hygiene of individuals with IDs who were looked after by caregivers involved in the education/training sessions. 27,29,33,35It was difficult to compare studies because of the different indicators of oral hygiene used (e.g., mean plaque index scores and oral hygiene index); however, all the studies revealed a significant improvement in oral hygiene indicators.

Studies Related to Knowledge, Attitudes, and Behaviors
Knowledge on oral health among caregivers was assessed using pre-and post-test questionnaires, and then the results were compared.Almost all studies reported a considerable improvement in the knowledge of caregivers after the completion of the intervention period.Changes in the behaviors and attitudes were also reported, with an increase in the number of caregivers during the tooth-brushing session appearing to result in more compliance in oral hygiene.
The results also showed that educating and training the caregivers resulted in improvements in the tooth-brushing habits of individuals with IDs.

Discussion
ndividuals with IDs vary in their ability to learn new skills and develop good oral health practices depending on their cognitive ability; however, findings of this study revealed that individuals with IDs who received some training in oral health practices demonstrated their ability to adopt efficient toothbrushing behaviors when they received systematic instructions, continuous evaluation, and reinforcements. 25,30,36The majority of studies involved in this review did not assess the cognitive ability of the participants with IDs, so it is not appropriate to generalize the effectiveness of the interventions among all individuals with varying degree of IDs.It is also important to realize that the effectiveness of the implemented interventions was assessed over a relatively short period of time, and therefore long-term effectiveness is still not clear, although most of the researchers stated the need of long-term follow-up and assessment. 11,14,15Although there is universal acceptance of the fact that more needs to be done in terms of care of individuals with IDs, yet there is a discrepancy in terms of geographical location where certain locations have been found to lack more in terms of oral healthcare of individuals with IDs. 44In a recent study, it was concluded that longer-term caregiver interventions, as well as on-site support for oral care, are necessary to evaluate outcomes for individuals with developmental and IDs with the goal of reducing the burden of oral disease.However, the same study noted that increased knowledge alone is not adequate to bring about and maintain positive oral health behavior change.Longer-term interventions and more caregiver involvement are important. 45ost individuals with IDs lack the cognitive ability to complete oral hygiene for themselves, and rely mainly on their caregivers to help them or even to perform it for them. 14oreover, caregivers for people with disabilities have been shown to possess a deficiency in adequate oral health attitude. 11Studies have also shown that caregivers reported a feeling of discomfort or a lack of success when performing oral hygiene practices to their clients (people with IDs) because of inadequate knowledge or training. 11,31,33It has been recommended that to improve desirable oral health outcomes for caregivers of individuals with disabilities, dental education plus training programs should be prioritized. 11So, these deficits are considered to be barriers for providing optimal oral care to individuals with IDs, which might risk their health and quality of life in general. 3,41Although there were some methodological limitations in the studies reviewed, the results of the interventions aimed at improving the oral health knowledge, behaviors, and attitudes of caregivers of individuals with IDs revealed an improvement in the caregivers' oral health knowledge, behaviors, and attitudes as well as the oral hygiene of individuals with IDs.The caregivers may desire more knowledge for the oral healthcare of individuals with IDs.Similarly, parents of individuals with IDs especially during the childhood of individuals with IDs seem to benefit a great deal from oral healthcare advice for their children.After an oral health promotional event in Riyadh, majority of the parents and caregivers of children with special healthcare needs were highly satisfied by oral health education that enabled them to take better care of their children. 46Therefore, educating and raising awareness about oral healthcare among people who are associated with the care of individuals with IDs seem to be of great importance.Likewise, in a pilot study done by Liu et al in 2021, new approaches like the use of a board game seem to be beneficial for promoting oral health knowledge among individuals with IDs. 47ocus on the initial and ongoing training of both individuals with IDs as well as their caregivers is very important. 489][50] However, it has also been proposed that a uniform approach to supporting oral health for individuals with developmental and IDs is unlikely to succeed until a system-based approach is adopted to address the diverse needs of such a population. 13Therefore, future trials are needed that use clearly defined participant characteristics and outcomes to increase precision and decrease bias.Use of validated outcome measures would standardize comparisons used for long-term follow-up.

Conclusion
The existing studies have shown improvement in desirable oral health outcomes using oral health promotion among individuals with IDs and their caregivers.However, it is difficult to measure the exact effectiveness of such measures unless they are persistent and perseverant in nature.Educational intervention in terms of oral health promotion seems to yield benefit for both individuals with IDs and their caregivers in terms of improved knowledge, attitude, and oral health behaviors, but this needs to be implemented for a long term.More objective measures stating definitive outcomes need to be investigated.Since the effects of such interventions/activities have been slow to meet the needs of this population in general, more research and more such targeted activities are needed.

Recommendations
Efforts should be made to develop a model for effective oral health promotion, and improving the oral health status of people with IDs.There is also a need to develop a standardized method of measuring and assessing the outcomes of such interventions, and it should include measures of both objective indicators (such as plaque index or gingival index, caries prevalence) and more subjective ones (such as behavior change and/or attitudes, quality of life) among individuals with IDs and their caregivers.

Fig. 1
Fig. 1 Describes the search strategy according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) flow diagram.
method of allocation, or similarity between groups described?

Table 1
The population, intervention, comparison, and outcome (PICO) parameters for systematic reviews InterventionOral health promotion only-like oral health education/oral hygiene instructions Does not include treatment based/pharmacological intervention Comparison Not applicable Outcome Includes 1. Clinical outcome-plaque levels, oral hygiene status, gingival health 2. Observed /self-reported effects on oral health knowledge, attitude/behavior

Table 2
Inclusion and exclusion criteria for the studies eventually included in the systematic review

Table 3
The quality score of the studies included in the systematic review

Table 4
General characteristics of studies published on the effects of oral health promotion among individuals with intellectual disabilities (IDs) European Journal of Dentistry Vol.18No.1/2024 © 2023.The Author(s).

Table 5
General characteristics of studies published on the effects of oral health promotion among caregivers of individuals with intellectual disabilities (IDs)Oral Health Promotion for Intellectual Disabilities AlJameel et al. 61 intervention revealed participants' capability of adopting efficient tooth-brushing behavior when monitored daily, they failed to mention exactly how they reached this conclusion.
31,[40][41][42]ture search, it was clear that the interventions aimed at improving oral health status among people with IDs can be classified either as directed closely at individuals with IDs or aimed at educating and training the caregivers of people with IDs.Although there are studies available in the literature regarding oral health, access, and interventions among individuals with IDs,19,[40][41][42]not many of these have looked at the effectiveness of such activities.As individuals with ID are just a part of a wide spectrum of disabilities that is growing in number by each day,43it has been expressed that there is lack of validated means of measuring the impact of oral health interventions on care providers for individuals with IDs.31However, it was observed that the studies included in this review were conducted in a wide variety of settings and of varying study designs.Also, the recruitment criteria of ID participants were inconsistent across the studies.For instance, the participants with all grades of ID (mild/moderate/ severe) were included.It is noteworthy that the level of intellectual ability of a person directly effects the means for proper oral hygiene and self-care.In a study, with individuals having varying disabilities ranging from cerebral palsy to ID; Shah et al in 2015 concluded that these individuals have a high unmet oral health need 10 apart from having difficulties of proper oral healthcare access.