Summary: the "Third German Oral Health Study" of the Institute of German Dentists (IDZ), 1997

 

Methodological characteristics of the study (DMS III)

The present study by the Institut der Deutschen Zahnärzte [Institute of German Dentists] (IDZ), Cologne, known as the "Third German Oral Health Study" (DMS III according to its German initials), is intended as an inventory of the present (1997) state of the oral health, oral-health-related behaviour and use of dental treatment services of the population of Germany. The study is designed in the form of an epidemiological survey (of the cross-sectional study type) based on representative random samples of the population taken from the age cohorts of 12-year-olds (adolescents), 35-44-year-olds (adults) and 65-74-year-olds (senior citizens) of German nationality.

As usual in national population surveys, the samples were obtained by the technique of multi-stage stratified random sampling of subjects’ addresses taken from the registration databases of population registration offices. This procedure allowed exact delimitation of the three selected age groups. The first stage involved the selection of 90 sample points; these are selection units at municipality level, of which 60 were to represent the "old" (west German) and 30 the "new" (east German) Federal States. The east German States were thus overrepresented in terms of their proportion of the population, so as to yield statistically representative results for individual subgroups in both east and west.

The 90-point basis was chosen for reasons of logistics, random sample theory and economics. Firstly, 90 points were sufficient to reflect the structure of the Federal States, at least when combined in accordance with the Nielsen region classification. Secondly, they were not too many for the three calibrated survey teams to complete the field work within a survey period of six months. And thirdly, the total target complement of 36 subjects for each point was selected to yield a large enough body of data covering the three age groups and the "east" and "west" regions for valid statistical description and analysis.

Of the total of n = 5040 subjects invited to take part at the 90 sample points, 223 (4.4%) dropped out for quality-neutral reasons. The net random sample was obtained by deducting these from the gross random sample. The figure of n = 3065 subjects examined corresponds to an overall utilization rate of 63.6%. However, the actual proportion varied considerably between age groups. Percentage participation was 85.9 for the adolescents, 55.6 for the adults and 56.4 for the senior citizens.

Following the main examination phase, all those in the adult and senior citizen groups who had declined to participate were sent a short questionnaire (SQ) containing questions on sociodemographic parameters, dental health and prosthetic status. Those who failed to return the questionnaire were telephoned and requested to answer selected core questions. The resulting information was used to determine how the participants differed from the non-participants regarding several sociodemographic characteristics ("non-responder analysis"). The short questionnaires were responded to by 723 subjects ("SQ participants") a 60% response rate referred to the number of persons approached by letter or telephone after the main examinations. Ultimately, therefore, at least a short questionnaire with the principal basic information on the various matters covered by the survey was available for 78.6% of the subjects.

For evaluation the data were statistically weighted in such a way that the disproportion between the numbers of subjects in east and west Germany was eliminated. This means that the results, presented in each case as aggregate figures, and allowing for the relevant confidence intervals, are representative of Germany as a whole. The weighting factors were determined from the latest available official figures. Within the adult and senior citizen age groups, five-year age subgroups were distinguished.

Dental caries (adolescents)

A DMFT value of 1.7 was determined for all adolescents (12-year-olds). This means that the WHO’s target of less than 2 DMF teeth for 12-year-olds by the year 2000 has been met. The very low value of 1.4 in the old Federal States contrasts with an average of 2.6 in the new Federal States. The overall DMFS index is 2.6, the values for east and west Germany being 3.9 and 2.2 respectively. Both the proportion of adolescents with healthy natural dentition and the DMFT and DMFS values indicate that caries experience has declined appreciably in comparison with the results of other studies from a small number of recent years. The greatest improvement in health status is observed in adolescents of low educational level.

An increasing polarization of caries experience nevertheless persists. 21.5% of adolescents have 61.2% of all DMF teeth, while a high-risk group of only 7.9% of adolescents accounts for almost a third (29.6%) of all diseased teeth.

A high treatment level is observed in adolescents, nearly 80% of diseased teeth having been filled. However, an increased need for treatment is observed both in adolescents with poor oral hygiene and in those who use dental services predominantly in response to acute pathology.

The correlation between socioeconomic data and caries experience is less marked than in earlier IDZ studies (DMS I dating from 1989 and DMS II from 1992). The existing mix of group and individual prophylaxis - the latter having been included in the statutory health insurance system in 1992 -is manifestly appropriate for achieving substantially comparable dental health notwithstanding the influence of socioeconomic parameters. An important factor in this connection is fissure sealing. The favourable effect of sealing emerges particularly clearly in 12-year-olds with inadequate oral hygiene and in adolescents who visit the dentist mainly in response to acute pathology.

Overall, more than half the adolescents have had teeth sealed. It may be concluded from the data presented that the wider use of sealing would result in a further appreciable reduction of caries. The adolescents most affected by caries could be the main beneficiaries.

Dental caries (adults)

The DMFT value of 16.1 determined for adults (age range 35-44) differed only slightly as between the old and new Federal States. The overall DMFS index is 54.7. Comparison of DMFT values with previous studies shows that caries experience has remained constant. However, the treatment level has increased appreciably, the present figure being 92.5%.

Treatment needs are found to be significantly polarized. All the untreated carious teeth are accounted for by only 23.6% of the adult group. Missing teeth too are found to be concentrated in a small proportion of the subjects examined. However, the large mean number of 2,3 teeth with incipient and enamel lesions overall is indicative of a substantial preventive treatment need.

Adult caries is correlated with social class. In this age group correlations were also observed with the efficacy of daily oral hygiene.

Some 9.9% of all exposed root surfaces are no longer healthy. Like crown caries, root caries correlates with social class.

Dental caries (senior citizens)

A DMFT value of 23.6 was recorded for senior citizens in the age range 65-74. Senior citizens from the old and new Federal States had the same high level of caries. The overall DMFS index is 102.8. Comparison of the indices with earlier similar studies reveals that caries experience has remained unchanged over a period of two decades. However, the number of carious teeth has fallen significantly, while the number of filled teeth has risen; whereas the number of extracted teeth has remained relatively constant, it has declined in senior citizens from east Germany. The treatment level has increased substantially in consequence, amounting to 93.2% in dentate senior citizens.

The frequency distribution of caries experience shows only slight polarization. However, the proportion of teeth with incipient and enamel lesions (10% of existing teeth) indicates the need for a policy of preventive treatment in senior citizens.

In senior citizens as with other age groups, caries correlates with social class. Correlations with the efficacy of daily oral hygiene also emerged for this age group. Both results confirm the lifelong caries-inhibiting effect of regular preventive measures.

A polarization is evident in root caries, which is observed in only 20.5% of dentate senior citizens. 12.6% of all exposed root surfaces are no longer healthy. As with crown caries, the incidence of root caries is correlated with social class. Close statistical correlations are found to exist between crown and root caries.

The continued high level of caries in senior citizens in the age range 65-74 is due to neglect of health issues earlier in these subjects’ lives. For this reason, improvements will not be forthcoming in the short term. However, the correlations demonstrated with caries-relevant behaviour such as oral hygiene show that long-term policies for the prevention of crown and root caries will be successful.

Gingivitis (adolescents)

On the basis of the gingivitis prevalences measured in adolescents by the PBI, severe gingival inflammations (PBI 3 and 4) are present in 36.1% of adolescents. The somewhat more favourable picture revealed by the plaque index shows that although adolescents are in principle capable of cleaning their teeth thoroughly, they do not as comparison with the PBI shows do so regularly. Prevalence values for dental calculus are quite low at under 6% and do not indicate an increased therapeutic requirement in this age group.

Periodontitis (adults)

Like the adolescents, over half the adults examined were found to have plaque-free dentition. Adults in west Germany had appreciably more plaque-free teeth (65.7%) than adults in the east (39.3%). Again, adult women cleaned their teeth more thoroughly than adult men. Some 20% of adults had no gingival pathology at all.

The CPI measure of periodontal status showed maximum pocket depths of 5 mm in a third of adults. A severe form of periodontitis was observed in as many as 14.1% of those examined. The differences between east and west Germany were very marked where advanced periodontal disease was concerned. Whereas less than 10% of adults in the west had pockets of more than 5 mm, the equivalent proportion in east Germany was 31.3%. The prevalence of periodontal disease as measured by maximum loss of attachment averaged 4.8 mm. The extent and severity of periodontitis (ESI) confirm that the majority of the adult population have attachment losses. Yet severe periodontal disease, which greatly impairs the prognosis for retention of the teeth, was confined to a comparatively "small" group of about 30% of the adult population.

Periodontitis (senior citizens)

Only 32.0% of senior citizens were found to have plaque-free dentition; this was a smaller proportion than in the case of the adolescents and younger adults. Gingival inflammations were rather more frequent than in the younger age groups. Regional differences in this case were again very marked, with healthier conditions prevailing in the west. Sex-specific differences were slight among the senior citizens.

The increase in periodontal disease with age resulted in almost a doubling of the prevalence of pocket depths exceeding 5 mm in senior citizens (maximum CPI of 4 in 24.4% of subjects). Moreover, twice as many senior citizens in the east as in the west exhibited severe periodontal disease as measured by the CPI. Maximum loss of attachment in senior citizens (disregarding edentulous subjects) averaged 6.1 mm, an increase of 1.3 mm compared with the younger adults. The frequency of maximum attachment losses of ³ 4 mm was 84.2%, while the figure for values of ³ 6 mm was 55.2%. This is another indication of the increase in periodontitis with age. Average attachment losses in east Germany were higher at 6.5 mm than in the west (6.0 mm). The figure for men, 6.6 mm, was significantly higher than the women’s 5.7 mm.

The extent and severity of periodontal disease as measured by the ESI again increased significantly in senior citizens compared with the adult subjects. Average losses of attachment according to the ESI were also significantly higher than in the adult group.

With regard to the risk factors for the occurrence of periodontitis, smokers were affected by periodontal disease appreciably more frequently than non-smokers. No such correlations were observed for other risk factors discussed, such as diabetes mellitus (treated). However, the correlation with coronary heart disease (CHD) was again very significant: statistically, senior citizens with severe periodontal disease had a measurably higher frequency of CHD events in their lifetime personal health biographies (p = 0.038).

Dental prosthetic status (adults)

The natural dentition of adults in midlife (age 35-44) undergoes a change of form, which is manifested in caries-related tooth destruction (DT + FT = 12.2), gaps due to dental interventions (6.7 missing teeth, or 4.2 if the wisdom teeth are disregarded) and, in individual cases, complete edentulousness (1.1%).

The typical epidemiological situation is partial edentulousness, with a probability of not less than 2 gaps resulting from extractions. The rate of tooth loss is higher in east Germany than in west Germany (by 1.3 teeth). The population group of lower educational level has also lost significantly more teeth than the reference group with higher educational status (the difference being 2.8 teeth). Similarly, subjects who visit the dentist only in response to acute pathology have more missing teeth (1.7 more) than those attending for regular check-ups.

Prosthetic crown restorations are undertaken on average on 1.7 teeth. In terms of the number of carious and filled teeth, one such tooth in seven is found to receive a complete-crown restoration. Crown restorations are (still) appreciably less common in east than in west Germany (the ratio being 1:2.6).

The proportion of missing teeth (other than wisdom teeth) replaced by dentures in adults in midlife is 57%, removable prostheses (31%) being used more frequently than bridges (26%). The use of fixed prostheses is particularly infrequent in the east German random sample, where the proportion is 17% compared with 30% in the west. In comparison with the results of the Second German Oral Health Study (DMS II) dating from 1992, however, recourse to dental treatment services in the new Federal States is found to have increased. On average, one tooth more was replaced, while the number of teeth replaced by bridges tripled (from 0.3 to 0.9).

Dental prosthetic status (senior citizens)

The average number of missing teeth in the population of senior citizens (age range 65-74) is 21.6 (17.6 disregarding wisdom teeth). All the upper posterior teeth and the lower molars have been lost in 70% of senior citizens. Forty percent of subjects aged 65 to 74 still have an average of 14 natural teeth.

Edentulousness of the upper and lower jaws affects 24.8% of the German population of senior citizens. The figure for the upper jaw (44%) is significantly higher than for the lower (27%). Pronounced differences are observed between social classes: subjects of low educational level have a 28% higher frequency of upper-jaw edentulousness than those who left school with higher qualifications.

Some 90% of missing teeth (other than wisdom teeth) in the 65-74 age group have been replaced by dentures. The quantitative level of treatment is thus very good; regional and social differences are slight. However, fixed prostheses are little used (average one tooth), while implant dentures are very uncommon (0.03 teeth). Differences between east and west remain in the frequency of use of functional and preventive therapeutic appliances: in west Germany bridges are four times as common, and combined fixed and removable partial prostheses twice as common, as in the east.

Oral dysfunction (adults)

Symptoms of craniomandibular dysfunction (CMD) are common in the 35-44 age cohort. Objective pathology detectable by clinical examination was observed in over 50% of the population. The most frequent symptoms were temporomandibular joint sounds mainly jaw clicking indicative of alterations in the position and structure of the cartilaginous parts of the joint. Restricted jaw mobility, determined on the basis of limit values, was hardly ever observed.

Pain as the principal symptom of CMD was reported by approximately 5% of the age group, with women complaining of pain more often than men.

However, significant instances of pain typical of patients seeking treatment were seldom observed in the clinical examination. In such cases as did occur, the subjects concerned were much more likely to be women than men.

Treatment needs for CMD were determined mainly in accordance with the patients’ subjective wishes. The proportion of subjects expressing a current subjective need for treatment of CMD was 3.2%. This is a conservative estimate of overall treatment needs, as part of the treatment requirement for CMD is accounted for by dental activity directed towards "passive prevention" of CMD rather than primarily towards therapy of dysfunctions. The actual treatment need is therefore likely to be higher than its subjective component.

Oral dysfunction (senior citizens)

The results of this study prove that objective pathology identifiable by clinical examination increases with age. This finding is in line with international studies.

Temporomandibular joint sounds and the proportion of grating sounds indicative of degenerative alterations of the joint increased. Restricted jaw mobility was observed relatively frequently. However, the symptoms were perceived less by these subjects than by the group of adults in midlife. A contrary tendency in symptom frequency was thus observed, with anamnestic findings declining while clinical symptoms increased. Whereas departures from the "ideal condition" of the masticatory system were recorded with increasing frequency in older subjects, these apparently did not give rise to appreciable subjective impairment of the subjects’ lives. Most symptoms of craniomandibular dysfunction are not associated with progressive tissue damage to oral structures.

Pain, as the principal symptom of CMD, was reported by approximately 5% of this age group; pain was complained of more frequently by women than by men.

Treatment needs for CMD arose mainly out of the subjects subjective wishes. A current subjective CMD treatment need was recorded for 2,7% of the subjects. This represents a conservative estimate of the overall treatment requirement.

Alterations of the oral mucosa (adults and senior citizens)

The results of oral mucosa examination accruing from this study are consistent with those of earlier prevalence studies. In particular, they confirm data on oral leukoplakia, as well as OLP. Comparison of the results for the adult random sample with the prevalences for the sample of senior citizens reveals a significant increase in some forms of pathology in particular, denture-related erythema (denture stomatitis) in the latter group. Both morbidity of the oral mucosa and the number of alterations recorded per subject increase significantly in older subjects. Since some of these alterations in particular, precancerous ones may in certain circumstances be life-threatening, older patients should be carefully examined at regular intervals for any changes in the soft tissues of the mouth. It is essential to question the subjects concerned at the same time about their tobacco and alcohol consumption. Advising smokers or subjects who consume alcohol to excess to give up these habits could be a future objective of the dental profession as a whole.

Gerontological aspects of the results

The results of the parts of the DMS III study concerned with oral pathology in older subjects are borne out by other scientific investigations. They confirm the connections frequently reported in the literature between other forms of morbidity in particular, cardiovascular disease and the occurrence of periodontitis, as well as between diseases that limit mobility, such as arthritis, and oral hygiene. The results in terms of recourse to dental services and of socioeconomic variables reveal a familiar picture. Subjects of low educational status and with lower incomes are more likely to go to the dentist only in response to acute pathology, tend to behave in ways that present health risks, and are more inclined to suffer from oral conditions such as caries and periodontitis.

Sociological aspects of the results

The sociological element of the results highlights the intimate intrinsic connections between dental and sociological issues in terms of prevention, therapy and rehabilitation alike. A markedly internal orientation to prophylaxis was observed in the health locus of control: some four fifths of the respondents (slightly less in the case of senior citizens) thought they could do "very much" or "a great deal" to influence the condition of their own teeth. In other words, adolescents, adults and senior citizens all show a clear inclination to contribute actively to prevention of dental pathology in themselves.

This propensity for active participation is important in that it could be used as a basis for further raising the level of oral hygiene practised by the population. The results of the questionnaire, as evaluated and combined to yield a three-dimensional behaviour index (covering the frequency, time and duration of tooth cleaning), show that only just under a third of respondents achieve the "good oral hygiene" standard; in the case of senior citizens, this proportion falls to as low as about 14%. Another noteworthy point, which, however, agrees with other sociological surveys in this field, is that on the whole women have better oral hygiene than men, while subjects with a higher educational level (as an indicator of social class) care for their teeth more thoroughly than persons with lower educational attainments. This social-class specificity of oral hygiene behaviour seems to us to be significant, in that it shows the importance of improved targeting of campaigns and measures for the prevention of oral pathology.

On the issue of the standard of oral hygiene practised, combined evaluation of sociological behaviour data and dental findings reveals a significant statistical correlation between the amount of plaque observed in clinical examinations and oral hygiene level.

Cariogenic "snacks between meals" are found to be widespread in the population. This applies equally to the adolescent and adult-midlife cohorts (senior citizens were not asked this question); more than one third of respondents report the ingestion of three or more between-meals snacks per day, with "fresh fruit" and "sweets" high on the list of preferences.

Regular "check-ups" predominate significantly in recourse to dental services by all three age groups, but decline equally significantly with age; prevention as a motive for visiting the dentist is more common in east than in west Germany. Educational level also has a clearly identifiable effect. Adults of higher educational level go to the dentist for a check-up more frequently than people of lower educational status. This correlation is not observed in the specific group of adolescents: "preventive visits" to the dentist among adolescents score just under 70%, irrespective of parental educational level. Another relevant point here is that more than four fifths of respondents in all three age cohorts state that they "always go to the same dentist" for treatment; this suggests the existence of a strong social bond between patient and dentist in the population.

On the basis of the Dental Impact Profile (DIP), the oral cavity was shown to have exceptionally high emotional significance, involving equally aspects of somatic functioning (chewing), general well-being, and socioaesthetic functions (smiling and laughing). Another relevant finding was that the aspects of chewing and biting, self-confidence and speech were most strongly modelled by the status of total edentulousness (including its rehabilitation with dentures).

A finding consistent with this overall result for the psychosocial impact of the masticatory apparatus is that the respondents always have very definite expectations (anticipatory cognitions) of a dental-prosthetic measure, the main requirements being not only "good quality and long life" but also "functionality" for chewing and biting and, in particular, "appearance". According to the respondents’ replies, subjective satisfaction with the actual dentures fitted is high: some 80% of both age cohorts report in the DMS III survey that they are "very satisfied" or "satisfied" with their prostheses.

Sponsors of the DMS III study

The "Third German Oral Health Study" (DMS III) was conducted as an autonomous research project of the Institut der Deutschen Zahnärzte/IDZ (Institute of German Dentists), a joint research institution of the Bundeszahnärztekammer/BZÄK (German Dental Association), Cologne, and the Kassenzahnärztliche Bundesvereinigung/KZBV (Federal Confederation of Sick Funds’ Dentists), Cologne. It was funded by the two sponsoring organizations, BZÄK and KZBV, with additional contributions from a support consortium made up of the KZVs [Regional Associations of Sick Funds Dentists] of Bavaria, Bremen, Freiburg, Hesse, Karlsruhe, Koblenz-Trier, Lower Saxony, North Rhine, Palatinate, Schleswig-Holstein, Stuttgart, Tübingen and Westphalia-Lippe.

Source: Micheelis W & Reich E. The Third German Oral Health Study (DMS III),
Institute of German Dentists (IDZ), Deutschen Ärzte - Verlag, Köln, 1999.