Motivational Interviewing for adolescent oral health

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Dental caries is a very common disease affecting a significant percentage of the world population. However, it is preventable if health behaviours and sell-care are adopted.  While the prevailing health education (PE) model can demonstrate improvements in oral health knowledge this seldom translated into behaviour change.  Motivational interviewing (MI) has been developed as an approach to address the limitations of PE and reviews have demonstrated positive effects in relation to a range of behaviours including oral health. Adolescents are a particularly challenging group as they are less future orientated and tend to see themselves as less vulnerable to health problems.

The aim of this trial was to evaluate the effectiveness of MI in improving adolescents’ oral health.


Fifteen secondary schools were randomly assigned to three groups: (I) prevailing health education (PE) , (II) MI, and (III) MI coupled with interactive dental caries risk assessment (MI + RA).  Adolescents 12-13yrs of age with no major systemic diseases and having unfavourable oral health behaviours (brushing less than twice a day/ snacking 3 or more times per day) were recruited.

  • Group I received a 30-minute oral health talk delivered to the whole school by an experienced dental hygienist and 3 leaflets.
  • Group II had a one-on-one face-to-face MI session, which lasted 15-30 minutes.
  • Group III – An interactive risk assessment programme was incorporated into different stages of MI sessions as appropriate.

Interventions were delivered by dental hygienists who had received coaching in MI from a panel of a health psychologist, a behaviour scientist, and a member of Motivational Interviewing Network for Trainers. Questionnaires at baseline, 6 and 12 months were used to collect data on demographic background, socioeconomic background oral health self-efficacy, and oral health behaviours. Total status and oral hygiene was recorded by a trained and calibrated examiner who was blinded to the group allocation. The primary outcome was dental caries increment.


  • 512 participants were enrolled in 3 groups (161, 163, 188 respectively)
  • 492 (96.1%) were available for follow up at 6 months and 482 (94.1%) at 12 months.
  • At baseline 45.3% had frequent snacking habits and 65.5% poor toothbrushing practice. 10.7% had both unfavourable habits.
  • Compared with PE, both MI groups showed more favourable self-efficacy and behaviours (in snacking and toothbrushing) at both time points.
  • At 12 months, the plaque score reduction was greatest in group III, followed by group II and group. No significant differences between group II and III were seen.
Frequent snacking habits

Odds ratio (95%CI)

Increased toothbrushing frequency

Odds ratio (95%CI)

Group I v Group II 7.12 (1.80 – 28.16) 5.26 (2.28 -12.16)
Group I v Group III 11.17 (2.90 -42.98) 11.45 (4.99 – 26.26)
Group II v Group III 0.64 (0.17-2.46) 0.46 (0.21 -1.02)


The authors concluded: –

MI was more effective than prevailing health education strategy in eliciting positive changes in adolescents’ oral health behaviours and preventing dental caries.


This well conducted cluster randomised controlled trial uses a relatively large sample size and had a low attrition rate. The trial demonstrates that MI was more effective than traditional heath education in changing health behaviours in adolescents at one year.  The trial also found significantly lower caries increment in the two MI groups  compared with the PE group as measured by the ICDAS index.  The authors note that further follow up at 24 months is planned and it will be interesting to see if the benefits are maintained both in terms of the behaviours and the impact on caries increment.


Primary paper

Wu L, Gao X, Lo ECM, Ho SMY, McGrath C, Wong MCM. Motivational Interviewing to Promote Oral Health in Adolescents. J Adolesc Health. 2017 Sep;61(3):378-384.doi: 10.1016/j.jadohealth.2017.03.010. Epub 2017 May 19. PubMed PMID: 28532895.

Other references

Dental Elf – 5th May 2014

The use of motivational interviewing to improve oral health has potential but needs more research

Dental Elf – 5th Sep 2017

Motivational interviewing for periodontal disease

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