With a high prevalence of edentulism identified, this section considers what this means for people with ID and explores the rehabilitation of this condition by using the most commonly applied treatment: complete removable dentures (CRDs).
2.3.1 Impact of total tooth loss
The completely edentulous person meets the World Health Organisation’s criteria for being physically disabled (Felton, 2015). Of the 16.5 million years lived with disability (YLDs), for which oral disease was accountable worldwide in 2013, edentulism accounted for one third of this burden (Vos et al.). A particular feature of edentulism is that it is non-reversible - its burden lasts for the duration of a person’s life. The functional impact of edentulism extends to nutrition, health and quality of life.
Firstly, among the general population, edentulism affects chewing efficiency, but more importantly it limits food choice, selection and preparation, especially of fruit and vegetables, which are rich in Vitamin C and fibre (Walls and Steele, 2004). Edentulism is also associated with malnutrition and, ironically, obesity (Felton, 2015, Sheiham et al., 2002). Diet and nutrition (along with inflammation and infection) are seen as important biological vectors for the relationship between tooth loss and mortality (Polzer et al., 2010). It is difficult to transfer these findings to people with ID, who face vastly different issues regarding difficulty eating and nutrition than do the general population – for example, malnutrition, a major concern among frail elderly, is a rarity among older adults with ID in Ireland (McCarron et al., 2014) and for whom feeding difficulties are far more complex than seen among the general population (Gravestock, 2003).
Secondly, edentulism is associated with general health. Dental diseases share common risk factors with other chronic, non-communicable diseases (Tyrovolas et al., 2016). A number of reviews, again among the general population have found that edentulism may increase the risk of cardiovascular disease, some cancers, diabetes, asthma, sleep apnoea, physical inactivity, chronic inflammatory changes to the upper gastro-intestinal tract, cognitive impairment, dementia and even death
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(Walls et al., 2000, Felton, 2015, Polzer et al., 2010, Emami et al., 2 013). Despite the significance of many of the conditions listed above for the welfare of the ageing population with ID (Haveman, 2009, McCarron et al., 2013), there has been, to date, no research specifically exploring the functional or health impact of edentulism and denture wear among adults with ID.
Thirdly, edentulism directly modifies normal orofacial physiology through alteration of the soft and hard tooth supporting tissues and orofacial musculature, leading to changes in facial height and appearance (Allen and McMillan, 2003, Bhoyar et al., 2012). The result is an aged facial appearance.
Lastly, researchers have also found that edentulism has a psychosocially disabling impact on those who have no teeth, among the population without ID at least. Edentulism is associated with depression (Kassebaum et al., 2014) and edentulous people may avoid participation in social activities (Rodrigues et al., 2012). Unique because of its focus on people with ID, Alves and colleagues found that an unmet need for prostheses was associated with worse quality of life among 119 adults with ID (Alves et al., 2016). Fiske and colleagues demonstrated, in a qualitative study, that denture wearers have low self-confidence, altered self-image and behaviour in socializing and forming close relationships (Fiske et al., 1998). Others found that the psychosocial impact may be offset somewhat, by wearing dentures (Jones et al., 2003), however it seems that implant-retained prostheses, rather than complete removable dentures, may best promote quality of life, amongst the general population at least (Awad et al., 2000). It seems that people with ID may experience less self-consciousness due to poor oral health (Hall et al., 2011), although some authors would disagree (Stiefel, 2002). We simply do not know the psychosocial impact of edentulism and its treatment among this group. While not the focus of the current study, research into oral health related quality of life among people with ID has been limited to impact assessment of dental treatment under anaesthesia (Chang et al., 2014, McGeown and Nunn, 2015). It could be argued that this should be refocused to expand our understanding of the relationship between edentulism, denture wear and oral health related quality of life among people with ID.
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2.3.2 Impact of complete denture wear
The immediate effect of denture wear is the replacement of lost hard and soft tissues with prosthetic material, customised to enable function. While this improves oro-facial function it does not fully restore it. In western society, most edentulous older people have dentures. Those who do not wear their dentures are more likely to have nutritional problems than those who do. Do Nascimento et al.
reported, in a study of their edentulous patient cohort, that those who do not wear dentures were at an increased risk of being both obese (OR = 2.88, CI=1.14-13.64) and underweight (OR=3.94, CI=1.12-7.40) (Luísa Helena do Nascimento et al., 2013). Saarela and colleagues reported that complete edentulism without denture wear was predictive of malnutrition among their institutionalised sample of 1,475 older adults in residential care (Saarela et al., 2014). Perhaps the explanation for these associations relate to the fact that unrestored edentulism is linked to increased difficulty in eating hard foods, increased mashed food consumption and decreased eating pleasure (Lamy et al., 1999), as well as poorer micronutrient intake (Han and Kim, 2016).
Given these differences, it is probably not surprising that when Polzer and colleagues reviewed the literature on mortality and edentulism, focusing on the remediating impact of denture wear, they found evidence, albeit of moderate to weak strength, that the use of prostheses was associated with reduced risk of death (Polzer et al., 2010). However, denture wear also brings risks. These include an increased risk of stomatitis, candidiasis and oral ulceration, which may offer a port of entry to pathogens and compromise the health of older adults (MacEntee et al., 1993, MacEntee et al., 1998). Denture plaque also has the potential for respiratory pathogenesis, though this is putative (Emami et al., 2013).
Recent research on the prosthetic management of edentulism among adults with ID is limited to a handful of case series reporting implant-supported prostheses (Romero-Perez et al., 2014, Oczakir et al., 2005, Lopez-Jimenez et al., 2003, Griess et al., 1998, Feijoo et al., 2012, Ekfeldt et al., 2013, Durham et al., 2006). With the exception of a handful of articles agreeing that denture wear is low among edentulous adults with ID, complete denture wear tends to have been overlooked by the research community.
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2.3.3 Conclusion on the impact of total tooth loss and denture wear in intellectual disability
Complete denture wear is uncommon among adults with ID who lose some or all of their teeth (Hall et al., 2011, Pregliasco et al., 2001, Kendall, 1991). The impact of tooth loss and its management is therefore important for this group. However, the impact of edentulism and denture wear for them is unclear. While we can extrapolate from the research above that edentulism is likely to have a negative impact on older people with ID, and that denture wear may ameliorate this to some degree, the risk from edentulism and the benefit of denture wear are simply unknown.