Why a New Approach?

Psychological theories are used to explain why some individuals engage in behaviors conducive to health, whereas others, despite knowing they have poor health fail to adopt healthier behaviors recommended by health care providers. A comparison across multiple health theories suggests humans have three basic psychological needs: the need to feel competent and self-efficacious; the need for autonomy where they are self-regulated rather than controlled by others expectations; and, the need to feel connected with others in meaningful social relationships.3-5 Although people need autonomy, they also need close relationships in which their thoughts, beliefs and feelings are respected. With respect to adopting healthier behaviors, the degree to which these three needs are met can increase or decrease the likelihood for sustained behavior change. This has important implications for oral health education and motivating patients. If the clinician does not clearly demonstrate respect and recognize the patient as an autonomous individual, they will fail to effectively engage the patient.

All humans experience some ambivalence, or simultaneous and contradictory attitudes or feelings, about changing existing behaviors. Often times, individuals are unaware they have ambivalent feelings about behavior change and this can work against them. Clinicians can play a pivotal role by helping patients uncover and verbalize ambivalence towards change. In other words, initiating communication about how the individual views positive and negative aspects of improved oral health behaviors may allow them to explore factors that increase or decrease internal motivation. Internal motivation is needed for sustained health behavior change. When clinicians attempt to impose motivation (e.g., through direct persuasion or advice given from an expert source), patients often respond with a guilt-induced transient change or simply sustain the current behavior. People may also respond by subtly pushing back and becoming more resistant to change. It is only when behaviors are internally directed and valued by the patient that sustained changes are possible. When healthy behaviors are sustained over time, better health outcomes are possible.

Originating in the addiction fields, many healthcare providers are now trained and using MI in primary care as well as dentistry. Bray and colleagues demonstrated that MI can be effectively learned and utilized by dental hygiene students.10 The effectiveness of the MI approach for more lasting behavior change with consequent improvements in health outcomes has been documented in clinical trials related to brushing frequency,13 plaque control,14 periodontal outcomes,21 dental caries and dental visits. One of the largest and most highly rated studies on MI and oral health consisted of a longitudinal study of children 0-5 years old and their caregivers.11 At the 2 year follow-up, the group receiving MI had a significantly higher proportion of children brushing seven nights per week at bedtime compared to the traditional health education group 35.45% to 25.33% respectively. While a higher proportion of the MI group (61.2%) assured children were bushing 2 times a day compared to 56% in the health education the result was not statistically significant.

Randomized controlled trails examining the effects of MI on dental caries report mixed results. For example, the Ismail study11 reported no significant difference in caries rates between the MI and traditional instruction group. Many of these trials delivered MI to caregivers and examined early childhood caries in matched child pairs. Except where noted caries trials compared MI to traditional health education to mothers of young children at high risk for early childhood caries.12 Mothers were randomly assigned to MI counseling or traditional health education and then followed for periods of 6 mos to 2 years to evaluate development of new lesions. Harrison (2012) and Weinstein (2006) showed a 46% and 35% decrease in early childhood caries respectively among those children whose mothers received MI.12,22 The inconsistent results between brushing behaviors and caries rates may be due in part to the aspects of the multifactorial nature of the disease process not impacted by behaviors.

Similarly, several studies have shown efficacy of MI for improving oral health measures in periodontal patients. Almomani and colleagues showed MI improved brushing behaviors in a sample of individuals with severe mental illness.13 This randomized clinical trial assigned 60 individuals to either a single, brief MI or traditional oral health education session. Subjects were all given a mechanical toothbrush and regular fluoride dentifrice to use for the duration of the 2 month study. Plaque scores, knowledge about oral health/mental illness and measures of self-regulation/autonomy were assessed after one and two months. Results revealed that a MI session prior to an oral health education session significantly enhanced autonomous (internal) motivation for regular brushing, increased oral health knowledge, and reduced plaque scores compared to oral health education alone (Table 1).

Table 1. Results from research by Almomani et al. comparing MI and traditional oral health education among patients with severe mental illness.8
Mean (SD)
Traditional Ed
Mean (SD)
Plaque Index §
4 weeks2.3(0.7)2.6(0.8)*
8 weeks1.9(0.7)2.5(0.9) ¥
Knowledge Score §
4 weeks31.6(2.4)*27.5(4.7)* ¥
8 weeks32.9(1.7)27.5(4.3) ¥
Self-regulation Scores
Introjected Regulation (Personal Guilt) £, ¡
4 weeks5.7(1.5)4.1(2.3)
8 weeks6.1(1.3)5.0(2.0)
External Regulation (Brushing for Others) £
4 weeks3.3(2.3)3.8(2.5)
8 weeks3.6(2.1)3.4(2.2)
Autonomous Regulation (Personal Reasons) £
4 weeks3.1(1.2)3.1(2.1)
8 weeks4.0(2.3)3.3(2.0)
§ = significant interaction effect
£ = significant main effect for time
¡ = significant main effect for group,
* = significant different from baseline to 4 weeks
** = significant different from 4 weeks to 8 weeks
¥ = significant group difference

Similar results were achieved in a clinical trial of MI applied to adult chronic periodontal patients. Jönsson and colleagues randomized 113 periodontal patients to either standard oral hygiene education or a multi-session MI enhanced oral hygiene program.14 Plaque, proximal gingival index, global gingival index, and bleeding on probing were evaluated at baseline, 3 month and 12 month follow-up visits. Results showed the MI enhanced education resulted in a significant improvement in all oral health measures. Plaque and GI scores for this trial are displayed in Table 2.

Table 2. Results from research by Jönsson et al compares MI to standard oral hygiene education.9
Mean (SD)
Traditional Ed
Mean (SD)
Plaque Score (Full Mouth)
3 months0.17(0.11)*0.32(0.22)
12 months0.14(0.13)*0.31(0.16)
GI Scores (Full Mouth)
3 months0.27(0.14)*0.52(0.20)
12 months0.21(0.16)*0.50(0.17)
* = significant different from baseline

Two additional studies that used a single session of MI to improve oral health in periodontal patients failed to show similar efficacy. However, in both studies participants in MI and health education comparison groups improved significantly from baseline.16,17 The respective authors concluded that this lack of difference between the MI and traditional education group might be explained by the sample characteristics as well as the single session intervention. Many periodontal patients who seek care from specialists are already motivated to improve their oral health when they make an appointment, which may explain the improvement irrespective of intervention. Additionally, for some patients multiple sessions of MI might be necessary for behavior change to occur. The concept of the potential dose-response of MI for behavior change was further supported by a recent meta-analysis.18