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Periodontal examinations undertaken for epidemiological purposes that require gingival probing can be uncomfortable for many people. In addition these techniques are more invasive than methods currently used to determine tooth status in epidemiological examinations. There appears to be a fairly large proportion of people who are prepared to answer questions about their oral health but not undergo an examination, as shown during the 1988 survey of adult dental health in the United Kingdom where 18% of those who were content to be interviewed did not go on to be dentally examined.1 This could introduce bias in the assessment of periodontal conditions in a population particularly if declining to undergo a dental examination is associated with embarrassment about oral status and oral cleanliness. Self-reporting of oral health status, if it can be shown to be reasonably valid, may thus offer an opportunity to measure oral health in populations and groups in a way which many people could find more acceptable than undergoing a clinical examination, at a fraction of the cost of undertaking traditional epidemiological dental examinations and with potentially less bias. It could also offer a simple way of determining periodontal health in a local population or a way of monitoring targets for periodontal health.

Self-reporting questionnaires have previously been used for basic tooth conditions with a reasonable degree of success.1,2 There have also been a variety of self-reporting methods used for periodontal conditions.2,3,4,5,6,7 The range of information gathered in studies of self-reported periodontal health varies. Helöe asked people if they had ever had 'gum disease' after some common symptoms of gingival inflammation had been explained to them.2 This was compared with gingival conditions scored according to the Gingival Index of Löe and Silness.8 Brunswick and Nikias had adolescent patients rate their gum condition on a scale ranging from excellent to poor and compared this with an assessment made by a dentist of the same persons' overall oral health,3 and Glavind and Attström had people undertake a detailed oral examination of their own mouth using toothpicks, toothbrush and a mouth mirror together with a manual of instructions and intra-oral photographs to determine indicators such as mobility, migration, bleeding and gum colour.4 Tervonen and Knuuttila asked questions about bleeding from gums, inflammation and whether the person felt they had gum disease; the responses were compared to clinically derived CPITN scores.5 Kallio, Ainamo and Dusadeepan had people conduct a toothpick and toothbrush test to assess bleeding from gums and compared this with clinical recordings of gingival bleeding.6 Subsequently, Kallio et al. 1994 looked at self-reported 'gingivitis' and 'bleeding from gums' assessed by questionnaire in adolescents in comparison to CPITN scores.7

In each of these studies, excluding the technique of oral self-examination used by Tervonen and Knuutilla,5 while there were weak positive correlations between clinical evaluation and various methods of self-assessment of periodontal status it would be doubtful if any were sufficient to enable self-reporting to be used as a substitute for a screening examination for periodontal disease. In the case of the oral self-examination used by Tervonen and Knuutilla 81% of a group of patients with periodontal disease were reported to be able to detect one or more of the symptoms they were asked to look for. However, no indication was given of how the tests performed on people with no periodontal disease, as the aim of this particular exercise was to develop a motivational tool for patients with periodontal disease rather than a screening test.5 However, this means it is impossible to judge the specificity of the technique.

The objective of this study was to test a battery of questions as predictors of subsequently clinically assessed periodontal status. The battery was designed to include not only the person's perception of signs and symptoms of periodontal diseases but also other sources of information which a person might be exposed to, such as being told by their dentist that they have periodontal disease, and also behavioural factors such as dental attendance and smoking.

Methods

Ethical approval was sought and given by Tayside Committee on Medical Research Ethics. A target was set to obtain 100 patients with at least 20 teeth and no complicating medical histories from adults who were attending as casual patients (ie were not referred) at Dundee Dental Hospital and School. The examinations took place between June and September 1997. The patients were asked to give informed consent to taking part, after being told that the experiment would consist of them answering a questionnaire and then having a periodontal examination. Consent to take radiographs was not sought as it was not considered justifiable to irradiate patients for research purposes only. The dental examiner (ADG) did not look at the questionnaire responses prior to the dental examination. The target was obtained from 102 approaches (ie 2 people declined). The patients ranged in age from 19 to 77 years with a mean age of 38 years. The questionnaire was a list of factors associated with periodontal diseases (eg tooth migration and bleeding from gums) and influences on the disease (eg smoking). The questionnaires were numbered to match the examination forms but patient names were not recorded. The periodontal examination consisted of measurements from each tooth present of tooth mobility,9 plaque,10 bleeding,11together with the Community Periodontal Index of Treatment Need.12 The measurements of plaque and bleeding were recorded at four sites (buccal, lingual, mesial and distal) around each tooth and charted accordingly. Mobility was assessed for each tooth. The CPITN score was the worst score found at any site in each sextant. This was then used as the basis of the measure of pocketing which was based on the worst CPITN score across the sextants.

The results are presented as the sensitivity and specificity of particular responses to questions as a predictor of clinically derived scores of plaque, bleeding, pocketing or mobility. The cut-off points were chosen as they were listed as significant stages in periodontal disease assessment in a recent article in the British Dental Journal.13 These were as follows:

  • Plaque was indicated by the presence of plaque at more than 40% of the sites examined which has been termed 'unsatisfactory'13

  • Bleeding was indicated by the presence of bleeding at more than 40% of the sites examined which has also been described as 'unsatisfactory' in non-smokers13 although in the case of Table 1 it is also applied to those who admitted smoking

    Table 1
    Full size table

  • Pocketing was taken as being indicated by the presence of any pockets of 4 mm or greater

  • Mobility was taken as being indicated by some horizontal mobility greater than 0.2 mm.

As with all thresholds, it may be contended that these do not divide people into exclusive categories. For example, bleeding at less than 40% of sites may be clinically significant in some individual cases. However, thresholds are concerned with issues to do with the probability of a person being in a particular condition, and these thresholds have been proposed and received acceptance through their publication in a scientific journal.

The sensitivity of a response is the proportion of those who had pocketing who responded in the way indicated. The specificity of a response is the proportion of those who did not have pocketing who did not respond in the way indicated. Sensitivity and specificity are presented as these, unlike positive and negative predictive values, are independent of the prevalence of the condition in the sample.14 Sensitivity and specificity values range from 0 to 1, where 1 indicates complete agreement between the test under evaluation and the gold standard (in this case the questionnaire items and the clinical test results respectively). The CPITN scoring system is based purely on pocket depth and takes no account of loss of attachment that is the measure normally used to distinguish between gingivitis (where no loss of attachment occurs) and (where loss of attachment does occur). In this paper the term 'indicators of current periodontal condition' is used to define what is being measured by CPITN.

Results

Table 1 shows the sensitivity and specificity of the questionnaire responses to predict each of the indicators of current periodontal conditions (plaque, bleeding, pocketing and tooth mobility). Only four questions produced sensitivity and specificity scores greater than 0.5. These were: (1) Whether the person was aware of the gaps between their teeth getting bigger or trapping food and, (2) Whether they could see more of the roots of their teeth than in the past; these two items were indicative of the person having some clinically detected pocketing or some tooth mobility, (3) Admitting to smoking in relation to a clinically derived plaque score, and (4) Self-reported tooth sensitivity in relation to having bleeding on probing at more than 40% of gum sites examined.

Many of the questions had high specificity and so would be good at predicting that a person would not have some of the periodontal disease indicators. For example, most persons who did not have clinical signs of periodontal disease said they did not think they were being treated for it (specificity 0.95–1.00). However, this item also had very low sensitivity showing that most people who had clinical signs of the periodontal diseases also thought they were not being treated for it.

The self-reported experience of having bleeding gums after brushing at some stage in life had reasonable sensitivity (0.75–0.88) as a predictor of the current periodontal disease indicators but its low specificity (0.18–0.25) indicates that many of those who were clinically assessed as being currently unaffected by periodontal disease had also experienced gingival bleeding after brushing at some time in their lives. Current self-reported experience of gingival bleeding showed the opposite trend. It had high specificity (0.86-0.88) but low sensitivity (0.19–0.35). The latter shows that many people with clinically detected signs of the periodontal diseases, (including clinically detected bleeding) were unaware of any bleeding after tooth-brushing. All but one of the people who said they thought they had 'gum disease' had been told this by their dentist which suggests that a person's awareness of their periodontal condition is highly dependent on it being diagnosed, and communicated to them, by a dentist. The low sensitivity of the item concerning awareness of being currently treated for periodontal disease (sensitivity = 0.06–0.17) shows that most of those who were affected by the disease indicators were either not being treated for the disease or not aware of being treated it.

Discussion

Overall, it was considered that the sensitivity and specificity values obtained were not sufficient to enable development of a question set which would be satisfactory as an indicator of periodontal conditions. However, this in itself should be put into perspective by comparison with the performance of some clinical tests in dentistry for detecting caries14 such as examples of clinical examinations undertaken by dentists (sensitivity = 0.13, specificity = 0.94) and fibreoptic transillumination (sensitivity = 0.13, specificity = 0.99) which have performed no better than many of the items reported in this paper as a means of detecting indicators of periodontal disease.

Although, there would appear to be little scope in developing a self-reporting instrument using items from the questionnaire which was developed in this study, the research does reveal some interesting aspects about the knowledge and understanding of periodontal diseases among the people who took part in the study. Few of those with some indication of the periodontal diseases said they were aware of currently being treated for gum disease, yet many of these same people said they usually had a scale and polish (also defined as 'teeth scraped') when they went to a dentist. This suggests that they may be unaware of what a scale and polish was ultimately trying to achieve. The role of scaling and polishing in the dental care of the patients is difficult to discern from this type of study, however the comparatively low specificity of reports that the person usually had a scale and polish when attending a dentist (specificity = 0.38–0.49) shows that the majority of people who have no current clinical indications of periodontal diseases usually have a scale and polish when they visit a dentist. This might show that the scaling and polishing is effective at eliminating these clinical indications. However, it is unclear how scaling and polishing when visiting a dentist could affect current plaque scores. Only 51% of those who scored high on plaque said they usually had a scale and polish when visiting a dentist compared with 62% who did not score high on plaque. This leads to an alternative possibility that scaling and polishing may be often provided for people who perhaps have little need for it and quite often not provided for patients who do.

It has been noted in the past that people seem to be unable to recognise they are affected by periodontal diseases2,15 even when they are also aware of gingival bleeding.16 The people in the current study were asked if their gums had ever bled when toothbrushing and if they currently bled when toothbrushing. This revealed that although many (88%) of those who had whose gums bled on probing were aware that their gums had bled at sometime, most of them (65%) were not aware of any current bleeding when toothbrushing. This suggests that although people can be aware of bleeding at some times there are other times when it goes unnoticed. It is also possible that people who have clinically detectable signs of periodontal disease are not being told this by their dentists: few people who had some indications of having periodontal disease could recall having been told they had it by their dentist (sensitivity = 0.15–0.32). This confirms previous results obtained for a similar questionnaire item asking Finnish adults if they had gum disease.5

Radiographs were not used to supplement the clinical examinations undertaken to validate the self-reporting instrument. This choice was made principally to avoid unnecessary irradiation of the patients. The CPITN technique does not require taking radiographs.12 The use of radiographs would therefore have contributed nothing to the gold standard that was adopted. Radiographs are primarily used in the periodontal context to determine alveolar bone loss, while the CPITN system is concerned with the assessment of periodontal treatment needs. As the self-reporting system under examination was concerned with self-assessed periodontal condition from outwardly observable signs and symptoms it was considered more appropriate to use a gold standard which had a similar basis.

The results obtained are for an opportunistic sample of people attending a dental hospital. The male to female ratio is indicative of the bias this introduces (66% of the sample were females). The most likely biasing factor in this type of sample is dental attendance behaviour; those who avoid dental treatment are likely to be under-represented in such a sample. Such bias may affect the prevalence of the conditions considered in this study but this would not affect the sensitivity and specificity values as these are independent of disease prevalence.14 The concern then would be whether those who avoid dental treatment are less likely or more likely to notice signs of dental disease than those who do not avoid dental treatment; and a case could be made for either possibility. Nevertheless, the general picture emerging from this study is that many people who display some indications of periodontal disease do not recognise their condition and are either unaware or are not receiving treatment for it. The results also indicate that the key to a patient realising that they have gum disease is to have been told by a dentist that they have it. In addition, there may be an inappropriate targeting of 'scaling and polishing' echoing concerns that, without an explicit strategy, periodontal care can easily become an uncoordinated procedure in general practice.17 Chestnutt and Kinane have reported that although many dentists in Scotland are confident in their ability to diagnose periodontal disease they are not confident in their ability to treat it.18 The results of the current study suggest that if Scotland's dentists are correct in their own self-assessment that they can diagnose periodontal disease, they would appear to be failing to pass this knowledge on to patients who exhibit signs of the disease. This may perhaps reflect the lack of confidence they have reported about their ability to manage the disease.18 Scotland's GDPs have also indicated that priority ought to be given to periodontology as a topic for postgraduate dental education.18,19 Such steps would seem crucial as there are indications that many dental practitioners are not informing their patients about disease presence, which may have medico-legal implications.18

The authors would like to thank the Oral and Dental Research Trust for funding this study. Thanks also to all the people who took part. Dr Nuttall is funded by the Chief Scientist Office of the Department of Health of the Scottish Office who do not necessarily share the views reported.