Health is not considered only as absence o f physical disease. Clinical measures are limited to evaluating oral health status and often fail to consider functional and psychosocial domainsions (Locker, 1989; Reisine and Locker, 1995; Sheiham and Spencer, 1997; Wilson and Cleary, 1995). The differences between clinical and perceived assessments have been discussed in some studies (Cushing et al., 1986;
Reisine and Bailit, 1980; Srisilapanan and Sheiham, 2001b; Tervonen and Knuuttila, 1988). However, the relationship between the clinical indictors and oral health-related quality o f life (OHRQoL) were investigated in numerous studies (Astrom et al., 2006; John et al., 2004; Leao and Sheiham, 1995; Locker and Miller, 1994; McGrath and Bedi, 2002; Slade and Spencer, 1994b; Srisilapanan and Sheiham,
Chapter 2 Literature review
2001a; Steele et al., 2004; Tsakos et al., 2004; Tsakos et al., 2006).
In a study to measure quality o f life using OIDP, Astrom et al, (2006) reported that the number o f missing teeth were significantly associated with OHRQoL. Apart from the number o f teeth, some studies have investigated the relationship between positions o f teeth as well.
Locker and Slade (1994) reported that the number o f missing teeth, followed by the number o f functional units and the number of posterior functional units were significantly related to oral impacts when they tested the OHIP in relation to clinical indicators o f tooth loss and periodontal disease.
A longitudinal and a cross-sectional survey were carried out in Brazil to investigate the relationships between satisfaction with the mouth and the number, position and condition o f teeth (Elias and Sheiham, 1999). The number, position and condition o f teeth were measured by clinical examination while a questionnaire was developed to assess satisfaction with the mouth, including subjective assessment o f appearance, pain, communication, function, comfort, satisfaction and “total satisfaction”. They found that there was a direct relationship between number o f teeth and total satisfaction. The higher the number o f teeth, the higher was the probability of satisfaction. There was a positive relationship between the probability o f satisfaction and number o f teeth until about 23 teeth. This trend was also observed for the number o f premolar pairs. The higher the number o f premolar o f pairs the higher was the probability o f satisfactions, until three premolar pairs. After that there were very few changes. For molar pairs, satisfaction was not related to the number o f molar pairs.
O f the different DMFT components, missing teeth was more associated with satisfaction than other components (decay teeth and filled teeth) (Elias and Sheiham,
1999).
A much clearer view about the relationship between clinical indicators o f dental status and subjective measure o f oral health-related quality o f life was obtained from Tsakos and colleague’s studies (Tsakos et al., 2004; Tsakos et al., 2006). Tsakos et al (2004) analysed the data from a cross-sectional survey in an elderly Greek population in Athens, Greece. The number o f teeth, filled teeth, the presence o f unfilled anterior spaces, the number o f OPs and the number o f POPs had significant associations with oral impacts in the dentate group. For example, 45.7% o f participants with 1-10 natural teeth reported oral impacts and 42.5% o f subjects with 11-20 natural teeth experienced oral impacts, while subjects with 21 or more teeth had significantly lower prevalence o f OIDP (28.5%). In the adjusted models, people with 1-10 teeth were 2.1 times more likely, and those with 11-20 teeth were 1.8 times more likely to experience oral impacts than those with 21 or more teeth. The number o f OPs, as well as number o f POPs had very strong relationship with oral impacts. After adjusting for the effects o f age, sex, and education, subjects with 0-8 OPs were 1.7 times more likely to report oral impacts when compared with those with 9-16 OPs. There were similar results for POPs. Subjects with 0-3 POPs were 1.6 times more likely to experience oral impacts when compared with those with 4-10 POPs (Tsakos et al 2004).
In Tsakos’s study, unfilled anterior spaces were calculated. There were significant relationships between the number o f unfilled anterior spaces and OHRQoL. Subjects with unfilled anterior spaces were 2.9 times more likely to experience oral impacts than those without. The authors suggest that unfilled anterior spaces were related to appearance and could be expected to affect many OIDP items, such as smiling, social
Chapter 2 Literature review
contacts and emotional stability apart from the obvious difficulties with eating and speaking.
A similar analysis on the data from a national representative sample o f the British older population (the NDNS in the UK) Tsakos et al (2006) found some different results. No significant relationship was found between the prevalence o f oral impacts and POPs, and unfilled anterior spaces. The possible reason for this was “the prevalence o f oral impacts is too low to demonstrate a statistically significant relationship” and a “different culture”.
The results from the above-mentioned studies indicate that among a variety o f different clinical measures, number o f teeth, and number o f occluding teeth, were particularly important factors affecting oral health-related quality o f life. This conclusion was also confirmed by other studies (Astrom et al., 2006; McGrath and Bedi, 2002; Srisilapanan and Sheiham, 2001a; Steele et al., 2004). In a study to test the relationship between age and tooth loss and oral health-related quality o f life in two national samples, Steele et al (2004), reported that tooth loss was independently associated with the summed OHIP scores in both countries. However, this relationship was not simple but appeared to have a plateau in the trend. For example, in the UK, subjects with 1-16 teeth had lowest mean OHIP scores while in Australia, the OHIP scores were much worse in subjects with 1-25 teeth, but did not differ significantly among the subgroups with 1-8, 9-16, 17-20 or 21-24 teeth.
Apart from number of teeth and number o f occluding pairs, other clinical indicators such as decayed teeth, decayed root, filled teeth, tooth mobility, periodontal disease, and dry mouth can affect oral health-related quality o f life. However, different results were obtained from different studies. For example, Slade et al (1996) reported that
missing teeth, retained root fragments, root-surface decay, periodontal pockets and problem-motivated dental visits were associated with higher levels o f oral impacts in a study o f older adults aged 65 years and over in South Australia, Ontario, and North Carolina. In addition, Gooch et al (1989) found that there were significant associations between oral impacts and decayed teeth and worsening periodontal disease. Srisilapanan and Sheiham (2001a) reported that the OIDP score was significantly associated with mobile teeth, but not with either decayed teeth or decay roots in a study o f elderly Thai people aged 60-74 years. Tsakos et al (2004, 2006) found that filled teeth were significantly related to the OIDP scores but no significant association existed between OIDP and tooth decay, root caries and tooth mobility in Greece, while oral impacts had no significant association with decayed teeth, filled teeth or decayed roots in British subjects. These different results may indicate that
“clinical disease affecting subjective perceptions o f well-being can be influenced by the nature o f the disease, as well as expectation, preferences, financial, social and psychological resources ” (Locker, 1992).