472 AUSTRALIAN AND NEW ZEALAND JOURNAL OF PUBLIC HEALTH 2010 vol. 34 no. 5© 2010 The Authors. Journal Compilation © 2010 Public Health Association of Australia

Dental knowledge and oral health among

middle-aged adults

David Brennan, John Spencer and Kaye Roberts-ThomsonAustralian Research Centre for Population Oral Health, School of Dentistry, University of Adelaide, South Australia

Social cognitive factors are central

to many models of determinants of

health behaviours, with knowledge

of behaviour-health linkages a factor in a

healthy lifestyle.1 Knowledge of oral disease

prevention should, in theory, underpin

positive dental behaviours and result in better

oral health outcomes. Stable favourable

dental beliefs from adolescence to early

adulthood are associated with better oral

health.2 However, knowledge of oral disease

prevention varies by education, income, age

and race,3,4 with misinformation common.5

While dental knowledge should underpin

dental behaviour, knowledge may not

necessarily translate into behaviour. Lack of

enabling characteristics may inhibit dental

behaviour, even if predisposed through

knowledge. For example, the cost of dental

care may restrict dental visiting behaviour

among those on lower incomes.6 Other non-

cost related barriers, such as availability

of dental providers7 and language barriers,

may hinder access to dental care.8 There

has been a shift in emphasis away from

individual behaviour to other processes,

particularly to explain the determinants of

social inequalities in oral health.9

Despite the shift away from lifestyle

explanations of oral health disparities, the

association of dental behaviour with oral

health has persisted.10,11 The aims of the study

were to assess the role of dental knowledge

on oral health by examining whether the

knowledge of behaviours related to the

prevention of caries was associated with

oral health, whether this dental knowledge

was associated with sociodemographic

Submitted: September 2009 Revision requested: December 2009 Accepted: January 2010Correspondence to:David S. Brennan, Australian Research Centre for Population Oral Health, School of Dentistry, University of Adelaide, South Australia 5005. Fax: (08) 8303 3070; e-mail: david.brennan@adelaide.edu.au

Abstract

Objective: Knowledge of oral disease

prevention should lead to better oral health

outcomes. The aims were to assess the

association of dental knowledge and oral

health.

Methods: A random sample of 45-54 year-

olds from Adelaide, South Australia, was

surveyed in 2004/05. Oral examinations

provided data on caries.

Results: A total of 879 persons returned

questionnaires (response=43.8%) with

709 (80.7%) examined. The majority rated

‘seeing a dentist regularly’ (63.0%), ‘regular

brushing of teeth’ (92.5%) and ‘using

fluoride toothpaste’ (52.2%) as ‘definitely

important’ in preventing tooth decay. The

percentage of persons who had a high

knowledge of tooth decay prevention was

59.9%. Multivariate analysis controlling

for sex, place of birth, education and

income showed (p<0.05) associations

of high dental knowledge of tooth decay

prevention with fewer decayed teeth

(β=-0.19) and more filled teeth (β=1.13).

Conclusions: Dental knowledge was

associated with oral health status.

Implications: Conveying of information

should be one part of oral health promotion

actions to improve oral health.

Key words: 45-54 year-olds, dental

knowledge, oral health, caries.

Aust NZ J Public Health. 2010; 34:472-5

doi: 10.1111/j.1753-6405.2010.00592.x

characteristics, and if dental knowledge

was associated with oral health, would

the association persist after adjusting for

sociodemographic characteristics.

MethodsSampling and data collection

A random sample 2,248 persons aged 45-

54 years from Adelaide, South Australia, was

drawn from the electoral roll and surveyed by

a mailed questionnaire during 2004-05 based

on the total design method.12 Respondents

were examined for tooth status, caries

experience and periodontal disease, and

the treatment need was recorded.13 Trained,

calibrated dentists conducted examinations

using mirrors and probes under standardised

illumination. Radiographs were not taken.

A subset of n=11 cases was re-examined to

assess the reliability of clinical measures.

Variables measuredTeeth were categorised as present or

missing, and the surfaces of tooth crowns

categorised as decayed, filled or sound.

The components of decayed, missing and

filled teeth (DMFT) were computed, with a

tooth designated as decayed if any coronal

surface was decayed. If at least one coronal

surface was filled, but there were no decayed

surfaces, the tooth was designated as filled.

The number of teeth missing due to caries

was summed.

Variables collected in the questionnaire

included dental knowledge of the prevention

of tooth decay (Table 1). These items

were based on previous reports of dental

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2010 vol. 34 no. 5 AUSTRALIAN AND NEW ZEALAND JOURNAL OF PUBLIC HEALTH 473© 2010 The Authors. Journal Compilation © 2010 Public Health Association of Australia

knowledge from the US and Australia.3,5 These were recorded

on a five-point Likert scale coded as 1=definitely not important,

2=probably not important, 3=neutral, 4=probably important and

5=definitely important. Other explanatory variables included sex,

place of birth, educational qualifications and household income.

AnalysisDental knowledge scores were calculated by summing the

responses to the dental knowledge items, with scores dichotomised

into higher and lower knowledge categories (coded as 1 and

0, respectively) using cut-off values of 29+. This defined high

knowledge as at least one response of ‘definitely important’ with

the remaining responses of ‘probably important’ or ‘definitely

important’. Dental knowledge was tested against sociodemographic

measures using chi-square statistics, and against oral health

measures of number of teeth, and number of decayed, missing and

filled teeth using linear regression. Multivariate regression models of

oral health status by dental knowledge were constructed, controlling

for sociodemographic characteristics.

ResultsResponse

A total of 879 persons responded (response rate=43.8%,

adjusting for out-of-scope persons, such as those no longer residing

at the sampled address). Oral examinations were performed on

709 persons (80.7% completion rate).

Distribution of dental knowledge responsesThe majority rated ‘seeing a dentist regularly’, ‘regular brushing

of teeth’ and ‘using fluoride toothpaste’ as ‘definitely important’ in

preventing tooth decay (Table 1). Except for ‘regular brushing of

teeth’ more than 20% rated all other items as ‘probably important’.

Dental knowledge scores ranged from seven to 35 (mean: 29.1;

95% CI: 28.8, 29.4), with 59.9% classified as higher knowledge.

Unadjusted associationsA higher percentage of females had a high dental knowledge of

tooth decay prevention compared to males, but dental knowledge

did not vary significantly by place of birth, education and income

Table 1: Distribution of responses to importance of items in preventing oral disease.

Definitely Probably Neutral Probably Definitely important important not important not important % % % % %

Prevention of tooth decay Seeing a dentist regularly 63.0 23.0 10.8 2.8 0.4

Drinking water with fluoride 43.5 36.1 15.3 3.4 1.8

Regular brushing of teeth 92.5 5.9 1.5 0.0 0.2

Regular flossing of teeth 45.5 32.4 17.6 3.7 0.9

Using fluoride toothpaste 52.2 31.5 11.9 2.6 1.8

Using fluoride mouthrinse 10.4 26.6 43.2 13.9 5.9Avoiding sweets between meals 27.7 38.7 26.8 6.0 0.0

Table 2: Unadjusted associations of dental knowledge scores by demographic and SES variables, and caries experience by dental knowledge scores, demographic and SES variables.

% with high knowledge Decayed teeth Missing teeth Filled teeth DMFT of tooth decay score

Tooth decay score % Mean (SE) Mean (SE) Mean (SE) Mean (SE)

High knowledge - 0.3 (0.04) 4.9 (0.2) 11.6 (0.2) 16.7 (0.3)

Lower knowledge - 0.5 (0.08) 5.5 (0.3) 10.4 (0.3) 16.4 (0.3)

p-value: - b ns b ns

Sex

Male 49.4 0.5 (0.07) 5.1 (0.3) 10.7 (0.3) 16.3 (0.3)

Female 69.9 0.3 (0.04) 5.4 (0.2) 11.2 (0.2) 16.9 (0.3)

p-value: b * ns ns ns

Place of birth

Australia 59.3 0.4 (0.05) 5.3 (0.2) 11.2 (0.2) 16.9 (0.2)

Overseas 61.9 0.3 (0.33) 5.2 (0.3) 10.4 (0.3) 16.0 (0.4)

p-value: ns ns ns a ns

Education

Tertiary 60.4 0.2 (0.03) 4.3 (0.2) 11.1 (0.3) 15.7 (0.3)

Secondary 60.0 0.5 (0.06) 5.9 (0.2) 10.9 (0.2) 17.4 (0.3)

p-value: ns b b ns **

Household income

$80,000+ 64.1 0.1 (0.03) 4.0 (0.2) 11.2 (0.3) 15.3 (0.4)

<$80,000 58.5 0.5 (0.05) 5.6 (0.2) 10.9 (0.2) 17.0 (0.2)p-value: ns b b ns b

Note: a) p<0.05, b) p<0.01.

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474 AUSTRALIAN AND NEW ZEALAND JOURNAL OF PUBLIC HEALTH 2010 vol. 34 no. 5© 2010 The Authors. Journal Compilation © 2010 Public Health Association of Australia

(Table 2). High dental knowledge of tooth decay prevention was

associated with fewer decayed teeth and more filled teeth. Females

had fewer decayed teeth than males. Persons born in Australia

had more filled teeth. Tertiary educated persons and persons from

higher income households had fewer decayed teeth and fewer

missing teeth, with a lower overall DMFT index.

Multivariate analysis of oral disease by dental knowledge and dental behaviour

Table 3 presents the multivariate results of models where each

independent variable was adjusted for the effects of all other

independent variables in the model. High dental knowledge of

tooth decay prevention was associated with fewer decayed teeth

and higher numbers of filled teeth. Males had more decayed teeth

than females. Numbers of filled teeth were higher for Australian-

born persons. Tertiary education and high income were both

associated with fewer decayed teeth, fewer missing teeth and lower

overall caries experience.

DiscussionRepresentativeness and reliability

While the response provided sufficient numbers for analysis,

the response rate was lower than anticipated. The electoral roll

should provide an adequate sampling frame for a population

survey of 45-54 year-olds. Sampling bias is unlikely, since voting

is compulsory for adults in Australia and the sample was drawn at

random. Some key demographic characteristics from the Census

showed a close approximation to that observed in the study.10,11

Comparison with other sample data showed a range of generally

small differences between these data and the study participants,

and reliability of the clinical measures was reported to be good

to excellent.10,11

Oral disease and dental knowledgeThe Ottawa Charter outlines health promotion as the process

of enabling people to increase control over, and to improve,

their health.14 Part of health promotion action involves the

development of personal skills through providing information,

education for health and enhancement of life skills. In this

study, dental knowledge was found to be associated with oral

health outcomes. High dental knowledge of the prevention of

tooth decay was associated with lower numbers of decayed teeth

and higher numbers of filled teeth. These associations persisted

after controlling for sex, place of birth, education and income,

indicating that dental knowledge had significant associations

independent of these demographic and socioeconomic factors.

While this could suggest that dental behaviour plays a mediating

role between dental knowledge and oral health, prospective

study designs are needed to establish the temporal sequence.

It is plausible that knowledge and behaviour could be mutually

reinforcing. For example, behaviour such as making a dental

visit may provide the opportunity for acquisition of knowledge

of the value of a regular visiting pattern and improved self-care

behaviour, such as tooth brushing. In turn, tooth brushing may

influence behaviour such as future visit pattern. The observed

association of less decay and more fillings among those with higher

dental knowledge indicates knowledge is associated with dental

visiting behaviour, which results in less untreated disease, but

overall caries experience was not influenced. The dental profession

has tended to focus on dental health education interventions; these

have been reported to effect knowledge levels, but not caries

increment.15 In addition, health promotion research has moved

away from this approach, towards an approach that acknowledges

the environmental and social supports for oral health.16

Table 3: Adjusted associations of caries experience by knowledge of prevention of tooth decay and covariates.

Decayed teeth Missing teeth Filled teeth DMFT

Beta (SE) Beta (SE) Beta (SE) Beta (SE)Tooth decay score

High knowledge -0.19 (0.08)a -0.47 (0.35) 1.13 (0.38)b 0.46 (0.43)

Lower knowledge Ref. Ref. Ref. Ref.

Sex

Male 0.21 (0.08)b -0.33 (0.34) -0.21 (0.37) -0.33 (0.42)

Female Ref. Ref. Ref. Ref.

Place of birth

Australia 0.04 (0.09) -0.18 (0.37) 0.86 (0.40)a 0.73 (0.46)

Overseas Ref. Ref. Ref. Ref.

Education

Tertiary -0.25 (0.08)b -1.31 (0.35)b 0.20 (0.43) -1.35 (0.43)b

Secondary Ref. Ref. Ref. Ref.

Household income

$80,000+ -0.27 (0.09)b -1.06 (0.40)b 0.12 (0.43) -1.21 (0.49)b

< $80,000 Ref. Ref. Ref. Ref.

Model p-value: <0.0001 <0.0001 0.0106 <0.0001R-sq: 5.3% 4.2% 1.6% 3.5%

Notes: a) p<0.05, b) p<0.01.

Brennan, Spencer and Roberts-Thomson Article

2010 vol. 34 no. 5 AUSTRALIAN AND NEW ZEALAND JOURNAL OF PUBLIC HEALTH 475© 2010 The Authors. Journal Compilation © 2010 Public Health Association of Australia

Oral disease and lifestyle factorsWhile an association between knowledge and health status

was evident in the findings of the present study, previous reports

have demonstrated associations between dental behaviour and

oral health status.10,11 The implications of a focus on individual

knowledge and behaviour need to be considered cautiously.

Lifestyle interventions have been criticised for their limited

effectiveness in producing sustained improvements in oral health

or for reducing oral health inequalities.9 Social cognitive factors

such as knowledge can differentiate between individuals from

the same background in their propensity to perform behaviours.1

However, lifestyle behavioural choices may be largely determined

and conditioned by the social environments in which individuals

live and work.9 Health promotion interventions may require

social change to alter cultural perceptions that drive individual

behaviours.16 However, if there are associations of dental

knowledge with dental behaviour and, ultimately, with oral health

status there may be scope for the development of more appropriate

information and ways of conveying that information to the public

with respect to the level at which oral health messages are pitched,

the channels through which they are communicated and degree

to which they are targeted.5 In addition to developing personal

skills through provision of information, health promotion involves

healthy public policy, reorientation of health services and the

creation of supportive environments.14 In this paper, knowledge

was specifically defined as knowledge of behaviours for prevention

of a particular oral disease, caries.

ConclusionsThe association of dental knowledge with oral health status

supports the need for the conveying of information as one part of

oral health promotion actions to improve oral health.

AcknowledgementsFunded by a National Health and Medical Research Council

project grant (#250316).

References1. Conner M, Norman P. Predicting Health Behaviour. Research and Practice with

Social Cognition Models. Buckingham (UK): Open University Press; 1995.2. Broadbent JM, Thomson WM, Poulton R. Oral health beliefs in adolescence

and oral health in young adulthood. J Dent Res. 2006;85:339-43.3. Corbin SB, Maas WR, Kleinman DV, Backinger CL. 1985 NHIS findings on

public knowledge and attitudes about oral diseases and preventive measures. Public Health Rep. 1987;102:53-60.

4. Gift HC, Corbin SB, Nowjack-Raymer RE. Public knowledge of prevention of dental disease. Public Health Rep. 1994;109:397-404.

5. Roberts-Thomson KF, Spencer AJ. Public knowledge of the prevention of dental decay and gum diseases. Aust Dent J. 1999;44:253-8.

6. Roberts-Thomson K, Brennan DS, Spencer AJ. Social inequality in the use and comprehensiveness of dental services. Aust J Public Health. 1995;19:80-5.

7. Federation Dentaire Internationale. Improving access to oral healthcare. Int Dent J. 1986;36:113-4.

8. Schofield T. The health of Australians of non-English-speaking background: key concerns. Aust J Public Health. 1995;19:117-9.

9. Watt RG. From victim blaming to upstream action: tackling the social determinants of oral health inequalities. Community Dent Oral Epidemiol. 2007;35:1-11.

10. Brennan DS, Spencer AJ, Roberts-Thomson KF. Caries experience among 45-54 year-olds in Adelaide, South Australia. Aust Dent J. 2007;52:122-7.

11. Brennan DS, Spencer AJ, Roberts-Thomson KF. Periodontal disease among 45-54 year-olds in Adelaide, South Australia Aust Dent J. 2007;52:55-60.

12. Dillman DA. Mail and Telephone Surveys. The Total Design Method. New York (NY): John Wiley; 1978.

13. National Institute of Dental Research. Oral Health Surveys of the National Institute of Dental Research. Diagnostic Criteria and Procedures. Washington (DC): United States Department of Health and Human Services; 1987.

14. World Health Organization [conference page on the Internet]. Geneva (CHE): WHO; 1986 [cited 2007 Nov 7]. The Ottawa Charter for Health Promotion. In: 1st Gobal Conference on Health Promotion: Ottawa; 1986 November 21 [cited 2007 Nov 7]. Available from: http://www.who.int/healthpromotion/conferences/previous/ottawa/en/print.html

15. Kay EJ, Locker D. Is dental health education effective? A systematic review of current evidence. Community Dent Oral Epidemiol. 1996;24:231-5.

16. Victorian Department of Human Services. Evidence-based Health Promotion Resources for Planning. No. 1 – Oral Health. Melbourne (AUST): State Government of Victoria; 2000.

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