Periodontal disease continues to be a major concern for dentists and patients. This paper reports the findings of the 1998 UK Adult Dental Health survey in relation to plaque, calculus, periodontal pocketing and loss of attachment. It is apparent from this study that moderate periodontal disease remains commonplace amongst UK adults and that the associated risk factors of plaque and calculus are in abundance, even amongst those who profess to be motivated about their oral health and attend the dentist regularly. The continued high prevalence of disease needs to be seen in the context of the far larger number of people who are now potentially at some risk, particularly in the older age groups, because of improvements in tooth retention. However, the cumulative effect of disease means that control of the periodontal diseases, even mild and slowly progressing disease, will be a key issue if large numbers of teeth are to be retained into old age. If that level of control is to be achieved we need a widespread improvement in our management of the disease, particularly in our ability to improve the oral cleanliness of the UK population.
As one of the two major oral conditions affecting the adult population, it is important to measure the prevalence of periodontal diseases as part of a national survey of oral health. Periodontal diseases have been recorded in some format in all of the previous surveys of adult dental health in the UK, but continuity has been a problem because of changing concepts of the disease and how best to record and report it.1 The methodology adopted in the 1998 study2 was designed to provide a 'best fit' between conflicting requirements. On one hand to allow comparison with previous studies,3 whilst on the other to reflect contemporary concepts and reflect the new patterns of disease resulting from increasing retention of natural teeth late into life.
A major consideration in adopting criteria was that they had to be as simple as possible. A large number of examiners required training and calibration and, with the examination taking place in the home rather than a surgery, the lighting, seating position and limited range of instruments made accurate recording of periodontal data a challenge. Even with very simple indices, there are still difficulties for survey examiners.4,5 Plaque and calculus can be difficult to see against a similarly coloured tooth surface, while measuring both periodontal pockets and loss of attachment simultaneously is a tiring and back straining process for the examiner. The pattern of the diseases is also complicated and makes reporting the data difficult, there being no simple indicator of disease experience and activity. An additional complicating factor is the very high prevalence of disease and its dependence on tooth retention so that describing these patterns in a way that is useful and meaningful to the profession is as great a challenge as collecting the data in the first place.
The variables recorded were visible plaque, calculus, pocketing and loss of attachment. Calculus has been measured consistently since the 1968 survey. Plaque on the other hand has not been recorded in its own right since the 1968 survey, though in 1978 debris, which included plaque, was recorded. A measurement of the extent of plaque was re-introduced in 1998 not only because of its fundamental role in the periodontal diseases, but also because it gives us an indication of the effectiveness of tooth cleaning, potentially the most important self-administered preventive dental intervention available for adults. Loss of attachment was also quantified for the first time in this survey. This is a more robust measure of historical disease experience than pocketing alone since it records movement of the point of attachment of the periodontal tissues from the normal position around the neck of the tooth. This is probably a more meaningful measure of the impact of disease in the growing population of dentate older adults than pocketing alone. Pocketing continued to be recorded separately, since it is still an important prognostic indicator and may also indicate a treatment need. The 1998 study reported very deep pockets (greater than 8.5 mm) for the first time so that more severe cases could be identified. The equipment was restricted to light, mirror and CPITN-C probe. A full description of the methodology and criteria appears in the main report.2
All dentate respondents who agreed to an oral examination were asked a series of screening questions to identify any whose health might theoretically be put at risk by the examination. Of the 3,817 respondents examined, 300 (8%) were excluded on these grounds. This is likely to be a higher proportion than in the previous 1988 study, particularly for older respondents, because of ethical committee advice to exclude additional respondents with prosthetic joints as well as those with any suspicion of cardiac valve defects who would have been excluded by the 1988 criteria. A further ten respondents declined the periodontal examination, having agreed to the rest of the examination, presumably because it involved probing soft tissue.
The prevalence of the various conditions can be described at mouth (subject) as well as tooth level. The latter is important where the prevalence is high at the mouth level since it is a more discriminating measure of differences between groups of subjects. Loss of attachment is reported in similar categories as pocketing, with 3.5 mm as the threshold for diagnosis since it was measured using the bands on the CPITN-C probe.
Plaque and calculus
Plaque was recorded only if it could be seen with the naked eye, without running an instrument along the gingival margin. Consequently, there had to be quite a large accumulation of plaque on the tooth before it was coded as present. In normal circumstances, such a deposit would take a number of days to accumulate. Calculus was recorded both visually and with the help of a CPITN probe.
The prevalence of recorded plaque was high; nearly three-quarters (72%) of subjects examined had visible plaque on at least one tooth and there were only relatively small differences between groups of respondents (Table 1, Fig. 1). There were also only relatively small differences between population subgroups in the mean proportion of respondents' teeth that had visible plaque on the surface. Perhaps surprisingly, the groups with the highest proportion of teeth affected by plaque also tended to have fewer teeth to clean. Overall, the mean proportion of teeth with plaque rose from 30% in the 25–34 year age group to 44% in the 65 years and over group. Those respondents who reported that they attended the dentist for regular check-ups were less likely to have plaque (68%) than other respondents (72–80%), and had a smaller proportion of teeth affected (29% compared to 43% in people who attend only with pain). In other words, they had cleaner mouths but although this difference is statistically significant, it is not great in practical terms.
One of the more interesting findings was that the participants who cleaned their teeth immediately before the examination (6%) still had, on average, plaque on almost one-third of their teeth; little different from those who chose not to. In this context, it is perhaps no great surprise that, although participants who reported cleaning their teeth twice daily or more were less likely to have visible plaque (69%) than people who cleaned once daily or less (79–87%), there were still over two-thirds of these self-declared regular brushers who had visible plaque deposits.
Around three-quarters (73%) of subjects had calculus present on at least one tooth and there was an increase in the mouth prevalence with age, from 61% amongst 16–24 year olds to 83% amongst those aged 65 years and over. The tooth prevalence of calculus showed a similar variation with age though the range was greater. There was a two-fold increase in the proportion of teeth with calculus with increasing age, from 15% in 16–24 year olds to 33% in those aged 65 years and over, reflecting the findings for plaque. Amongst those who reported that they attended the dentist regularly for check ups, 19% of teeth had calculus compared with 32% of teeth in those who reported that they only attended the dentist when troubled by symptoms. The mouth and tooth prevalence of calculus also varied by reported time since last dental visit; 68% of participants who reported that their last dental visit had been less than a year before the examination had calculus, this was compared with 84% of respondents who reported that their last dental visit had been between one and five years previously. At the level of the teeth, 19% of teeth in the former group had calculus present compared with 28% in the latter. As expected, the distribution of calculus at different sites in the mouth was not even; only 11% had calculus present on a maxillary canine or incisor (upper central sextant) compared with 67% who had calculus present on the corresponding mandibular teeth (lower central sextant). This reflects what dentists often report seeing in their patients, calculus affecting lower front teeth because of their close proximity to the submandibular salivary ducts, whilst upper front teeth are often the cleanest teeth in the mouth because people often take most care with them.
Pocketing was recorded in three categories based on the familiar CPI scoring system. Over half (54%) of subjects examined had moderate pocketing or worse (greater than 3.5 mm) on at least one tooth (Table 2, Fig. 2). There was a marked increase in the mouth prevalence with age from 34% amongst the 16–24 year age group to 67% amongst those aged 65 years and over, even though the latter age group had on average far fewer teeth and may well have had periodontally affected teeth extracted in the past. The mouth prevalence of deeper pocketing (greater than 5.5 mm) was 5% in all subjects and also varied by age; less than 1% in the 16–24 year age group compared with 15% in the 65 years and over age group. The mouth prevalence of very deep pocketing (greater than 8.5 mm) was only 1% amongst all dentate respondents. Differences in the prevalence of pocketing between groups of subjects other than by age were relatively small.
The site-specific nature of the experience of periodontal disease was reflected in the relatively low tooth prevalence compared with the mouth prevalence; 12% of teeth examined had pocketing greater than 3.5 mm compared with 54% of mouths. The tooth prevalence of pocketing greater than 3.5 mm varied greatly with age; there was nearly a five-fold difference between those aged 16–24 year age group (5%) and the 65 years and over age group (23%). Differences between social classes and by reported attendance pattern remained small, though those who reported visiting the dentist within the last year were almost half as likely to have moderate pockets as those who reported not having visited the dentist in the last five years (11% compared with 20%). An unexpected finding was the slight increase in the mouth and tooth prevalence of pocketing greater than 3.5 mm between those who reported that they cleaned twice a day and those who reported more frequent cleaning. Though the numbers were small, this may be because some of those who were cleaning more than twice a day were doing so because they were aware of having established disease and were making strenuous efforts to remove plaque.
Loss of attachment
Loss of attachment was measured from the level of the cemento-enamel junction to the base of the pocket. The millimetre categories used were the same as those for pocketing. In total, 43% of dentate respondents examined had loss of attachment greater than 3.5 mm on at least one tooth and there was an increase in the mouth prevalence with age from 14% amongst the 16–24 year age group to 85% amongst the 65 years and over age group (Table 3). The mouth prevalence of loss of attachment greater than 3.5 mm was lower than the mouth prevalence of pocketing greater than 3.5 mm in the younger age groups and higher in the 55–64 year and 65 years and over age groups. This reflects higher levels of gingival recession in older adults and 'false pocketing' resulting from mild gingival enlargement without attachment loss in younger people. Recession was likely to be a very common feature in the older age groups and reflect a lifetime's disease history. Because of this, loss of attachment, which takes account of recession, indicates the real threat to the tooth from loss of periodontal support more accurately than pocketing in older adults. The mouth prevalence of loss of attachment greater than 5.5 mm was 8% in all dentate respondents examined and also varied with age; less than 0.5% in the 16–24 year age group compared with 31% in the 65 years and over age group. As with pocketing, the tooth prevalence of loss of attachment was far lower than the mouth prevalence; 10% of teeth examined had loss of attachment of greater than 3.5 mm compared with 43% of mouths. The tooth prevalence of loss of attachment of greater than 3.5 mm varied greatly with age, being 2% in the 16–24 year age group compared with 30% in the 65 years and over age group. This suggests that much of the pocketing reported in younger age groups was 'false pocketing' resulting from enlarged gingivae rather than attachment loss. Differences between social classes and in reported attendance pattern were small.
Moderate disease is widespread, but it is those with severe disease who cause the greatest of clinical problems and these are the individuals who are at greatest risk of tooth loss. Although they occupy only a small proportion of the dentate population this group is important, but it is easy to lose sight of them in a mass of population data. Amongst the 5% who have a pocket of over 5.5 mm, they have on average nearly three teeth affected (mean 2.6) by such deep pocketing, whilst they will have around ten of their teeth affected by pocketing which is at least moderate (mean 11.4 teeth, 54% of all teeth). In other words, the average sufferer of severe disease will have a very high proportion of teeth affected by pockets at some level, but typically there will be relatively few which are severely affected at any one time and there will usually be a reasonable proportion of relatively unaffected teeth (Fig. 3). Loss of attachment of over 5.5 mm affects more people in the population than pocketing of the same depth, particularly amongst older adults, but the numbers and proportions of teeth affected in those with relatively advanced loss of attachment is strikingly similar to that for deep pocketing, and the distribution of affected teeth is similar (Fig. 4). Once again there are a few teeth severely affected, but on a base of teeth which are moderately affected.
The people who are more severely affected are rather difficult to single out or to profile. The social and gender influences appear to be negligible, they do not necessarily have the dirtiest mouths and they are not much more likely to be dental non-attenders. They are, however, likely to be older. Although this may in part be that the measures are of disease experience rather than activity, the increase in the prevalence of deep pockets and extensive loss of attachment later in life is quite dramatic.
The data derived from a large survey of this sort are necessarily crude. Only a limited number of variables are recorded and maintaining the accuracy of measurements is difficult. Examiners find it particularly difficult to probe posterior teeth during a home examination, so the prevalence of deep pocketing and loss of attachment is probably under-recorded. Nevertheless, the population sample is large, highly representative of the UK public and the data quality issues described will not greatly affect the differences between age groups or associated with reported attendance behaviour, nor the relative lack of differences between social and gender groups. As it is possible that inter-examiner variability could give biased results by geographical region we have avoided any comparison between areas, though there is no particular reason to expect any major effect in this regard either.
When looking at these results, it is worth bearing in mind that only dentate adults and standing teeth contribute to the data. The population experience of disease reported applies only to the 87% of the adult population who have some natural teeth, we know nothing about the former state of the teeth of the edentulous, though technically they are now unaffected. On the other hand, figures reported may well under-estimate historical disease experience, since mouths rendered edentate by disease and extracted teeth in partly dentate mouths (perhaps extracted because of periodontal disease) are both lost to the analysis.
Despite all of these considerations, the results of this study indicate that UK adults have a high prevalence of plaque and calculus on their teeth, with surprisingly little difference between those who report higher levels of dental motivation and those who do not. The regular brushers and reported regular dental attenders did have less plaque than the smaller groups of infrequent brushers and reported non-attenders, but many of the former still had visible plaque on a large proportion of their teeth. The only reasonable conclusion to draw from this is that, despite their apparent efforts, UK adults are not as efficient at plaque control as might be hoped. Oral hygiene is a huge public and personal health issue and improved hygiene could be expected to result in benefits in terms of periodontal disease and dental caries. There is clearly some room for improvement.
Differences in the prevalence of calculus between groups are likely to reflect differences not only in the frequency and effectiveness of tooth cleaning but also the use of dental services for the removal of calculus and the number of teeth present. The effect of reduced numbers of teeth in the mouth on the prevalence of calculus will be limited because the teeth most likely to be retained in those with partially dentate mouths are mandibular canines and incisors, teeth which are more likely to have calculus. This may partly account for the steeper trend in tooth prevalence associated with age. Calculus is however widespread in the UK adult population and the data suggest that dental services do have an impact in the removal of calculus, at least on the removal of visible calculus.
The prevalence of severe pocketing (greater than 5.5 mm) is low overall, but over half the subjects examined had at least one pocket over 3.5 mm present and 12% of teeth were similarly affected. This also increases quite sharply with age, underpinning the need for continued monitoring. The results for loss of attachment indicate a high prevalence of significant loss of attachment in older adults and this would merit closer study in future. Although it is reported in the same way as pocketing, the interpretation is a little different; any loss of attachment could be regarded as potentially pathological for the purposes of analysis whereas pocketing is usually only regarded as potentially pathological above about 3.5 mm. Loss of attachment in older adults is often a combination of extensive recession as well as some pocketing. The areas of recession may be where there was a deep pocket in the past, though in some cases we may be looking at creeping recession where deep pocketing was never present. The important point is that attachment loss is generally irreversible and these results show the extent to which attachment is lost over a lifetime where teeth are retained. Moderate and probably slowly progressing levels of disease, which will result in extensive attachment loss and pose a real threat to individual teeth over the course of a lifetime, have affected a significant proportion of the population by the time they reach retirement age. The fact that 85% of dentate people aged 65 years and over have at least some teeth which have seen over 3.5 mm of loss attachment suggests that low grade but slowly destructive disease is the norm.
Differences in the prevalence of pocketing and disease between various population subgroups were generally quite small. Assuming that inherent susceptibility does not vary between study groups, and there is nothing to suggest that it should except possibly with gender, the differences between groups are likely to represent the consequences of a wide range of different factors. These include the frequency and effectiveness of tooth cleaning, smoking and the use of dental services over a long period. The inclusion of tobacco use as a variable may be a valuable addition in future studies, since this is reported to be an important explanatory factor in the development of disease.7 Neither the reported frequency of oral hygiene practices nor the reported use of dental services seemed to be strongly associated with the prevalence of measurable disease. This finding should be interpreted with caution in view of the complex relationship between health behaviour and disease experience, for example people with identified disease may be making a greater effort to maintain their teeth. Despite these words of caution, it is difficult to escape the suggestion that neither dental services nor attempts at hygiene are having the impact on disease we might hope. Results from elsewhere in the survey suggest that regular dental-attenders benefit in real terms over a lifetime in terms of tooth retention, perhaps by up to as much as five more retained teeth by the age of 65 years.2 The lack of any major difference in the prevalence of periodontal disease according to reported attendance pattern may suggest that, although it is impossible to be certain of the mechanism, most of this benefit comes through restoration of the teeth, rather than management of periodontal diseases.
Disease of the periodontal tissues continues to be a commonplace finding in the UK, but, being a complex disease to measure, it is difficult to get a real feel for long-term trends. The increased retention of natural teeth presents a particular problem in this regard because as more teeth are retained there are more sites that may be affected by disease, and more people with teeth to be affected. Therefore, we may in part be victims of success on other fronts; even if our management of the disease was improving, the retention of teeth might make it difficult to demonstrate this until we make a considerable impact on the disease. The continued high prevalence needs to be seen in the context of the far larger number of people who are now potentially at some risk, particularly in the older age groups. The cumulative effect of disease means that control of the periodontal diseases, even mild and slowly progressing disease, will be a key issue if large numbers of teeth are to be retained into old age. If that level of control is to be achieved we need a widespread improvement in our management of the disease, but particularly in our ability to improve the oral cleanliness of the majority of the UK population.
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We are grateful to the dental examiners, NHS organizers and the Office for National Statistics for their assistance with this study.
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Morris, A., Steele, J. & White, D. The oral cleanliness and periodontal health of UK adults in 1998. Br Dent J 191, 186–192 (2001). https://doi.org/10.1038/sj.bdj.4801135
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