Unitat didàctica 3: Termodinàmica

Ability and those had General Eating Difficulty in the present study. This finding may indicate that some older Chinese people in Guangxi did not express dissatisfaction with chewing ability even though they had eating difficulty.

One o f measures o f eating difficulty used in this study was Index o f Eating Difficulty (IED). The IED is a new index developed as part o f the work for this thesis, which was based on the Chewing Ability Index (Leake, 1990) but modified both in terms o f types o f foods so that it was relevant for the Chinese populations and scoring methods. It has five categories o f Chinese foods. These five categories o f indicator foods include 10 Chinese foods with different textures. As this was a new index, the reliability and validity were tested. Informal and formal discussions with some academics, nutritionists, and epidemiologists were carried out, two pilot studies were conducted. The results showed that the IED had a good reliability, the coefficient o f reproducibility and the coefficient o f scalability were 0.99 and 0.89 respectively, which are above acceptable values. In the present study, unlike in the studies using the Chewing Ability Index (CAI) developed by Leake (1990), the index was not used on an interval but on an ordinal scale because we cannot assume that the differences between two scores are equal. For example, the difference between score 0 (eat everything) and score 1 (eat everything except the foods in category 6) is not equal to the difference between score 2 and score 3 and so on (Table 4.3). Actually, this is a critique applied to all similar measures and not only the CAI. Therefore, the median and the prevalence o f the different categories o f the IED, not the mean and the standard deviation, were reported in the present study.

The findings showed that 84.2% o f subjects had an IED o f 0, suggesting that these subjects could eat all foods listed; only 2.2% o f subjects had an IED o f 5 meaning that they could not eat any o f foods listed (Table 5.19). This very high prevalence o f people

with an IED o f 0 could be perceived as being contradictory to the fact that 48.3% o f people reported that they had some difficulty or could not eat some foods listed at all.

However, it should be apparent questions on dietary restriction and questions for the IED were different. There were three answers to question on dietary restriction, namely

“could eat easily”, “could eat with some difficulty” and “could not eat at all” for each food item listed on questionnaires, but there were just two answers, namely “could eat ” and “could not eat” on questionnaires for the IED (Appendix 4). So, people could answer “could eat” even if they had some difficulty eating the foods. People who answered “could eat” for the IED included people who answered “could eat easily” and people who answered “could eat with some difficulty” for some food items. People with an IED o f 0 included people reporting they could eat some foods with some difficulty.

In the present study, the time frame for the OIDP eating impact referred to the past six months, while General Eating Difficulty focused on what occurred at the time o f interview. Therefore, some subjects could have the OIDP eating impact before the interview and had completely recovered when interviewed whereby they may report no general difficulty eating. This may be why the percentage o f people with the OIDP eating impact was higher than the percentage o f people with General Eating Difficulty.

Subjectively assessed Dissatisfaction with Chewing Ability measures have been used in many studies (Andersson et al., 2004; Gilbert et al., 1998; Locker, 1992; Locker, 2002;

Miura et al., 2001; Miura et al., 2005; Peek et al., 2002; Sarita et al., 2003). The prevalence o f Dissatisfaction with Chewing Ability in the present study (41.3%) was higher than in some studies (Gilbert et al., 1998; Locker, 2002; Peek et al., 2002).

Locker (2002) reported that 12.6% were dissatisfied with their chewing ability in a population o f similar age to that used in this study. In the Florida Dental Care Study,

C hapter 6 Discussion and conclusions

16% o f subjects were dissatisfied with their chewing ability (Gilbert et al., 1998). Both studies are comparable to the present study because the same single-item question asking subjects to rate their satisfaction was used.

Nearly half (48%) o f the Chinese people in the present study reported that they had some difficulty or could not eat salted roast chicken, roast pork ribs, roast duck or chicken. About one third had difficulty or could not eat apples. Even very common foods such as cooked sliced pork or cooked green vegetables, cooked cucumber and carrots posed difficulties in between 15-25% o f people (Table 5.23). The comparison o f our results with those from other studies is difficult because the foods used in this study differed from those in other countries. Only apples provide an example o f a food that can be used for international comparisons (Anastassiadou and Heath, 2002). For example, 36% o f dental subjects in the present study had difficulty or could not eat apples compared with 28% o f dentate subjects in the NDNS (Steele et al., 1998). The percentages o f people who could eat some hard foods with some difficulty or not eat them at all were higher in the present study than in the NDNS. The possible reasons are that in general some Chinese foods on the list like salted roast chicken, roast pork ribs, roast duck or chicken, boiled chicken or duck were harder compared to foods listed in the NDNS because the bones were not removed from the chicken, duck and pork ribs.

It is difficult to compare the results o f the IED from the present study with the findings from other studies because the foods used and scoring systemin the present study differ from those in other studies done in a number o f countries. In addition, oral health and cultural attitudes to health also differ between the sample o f this study and the samples o f studies carried out in other countries, further hindering the comparability between the studies.(Gilbert et al., 1998; Gilbert et al., 2004; Leake, 1990; Miura et al., 1997; Miura

et al., 2000; Miura et al., 2003; Tsuga et al., 1998; Koyama et al., 2005; Kurita et al., 2001; Locker, 2002; Peek et al., 2002; Sarita et al., 2003; Takata et al., 2006). This was discussed in the literature review (section 2.1). The percentage o f people who could not eat apples was lower when compared with that found in Leake’s study. In Leake’s study, nearly 23% could not chew the whole apples without cutting it up. But in the present study, only 14% could not chew the whole apple (Table 5.2). There are two possible reasons for this. One is that some people who answered they could chew apples in our study included those who could chew apples with some difficulty, as stated earlier.

Actually, in the present study 36% o f subjects reported they could eat with some difficulty or could not eat the whole apple. Another reason is that there were some varieties o f soft apples in Guangxi and older people may choose these.

In most cases o f eating difficulty, the difficulties were probably related to chewing ability, but there may have been other factors involved. For example, in the south o f China, some foods like salted roast chicken, roast pork ribs, roast duck or chicken are regarded as too “hot” for older people. When people get older, they are more likely to eat soft or “cold” foods, like tofu in water, rice porridge, and boiled fish. In addition, older people may consider that eating hard foods can damage teeth because your teeth become fragile when you get older. They also consider that soft food can be very nutritious and as good as normal food after careful food preparation (Kwok et al., 2004).

Therefore, some people consider that older Chinese people prefer eating soft foods instead of eating hard foods. Then, they adapt to eating soft foods. This is a possible reason why perceived eating difficulty was much higher in the present study compared to other studies (Gilbert et al., 1998; Locker and Miller, 1994; Sheiham et al., 1999;

Sheiham and Steele, 2001).