Health action process approach in oral health behaviour: Target interventions, constructs and groups—A systematic review

Abstract

Objective

The aim of this study was to systematically map the Health Action Process Approach (HAPA)‐based interventions in dentistry in relation to the type of intervention, the target groups and the constructs of the HAPA model that are used in the study and to assess the clinical relevance of the studies.

Methods

A search in the databases of the National Library of Medicine (MEDLINE‐PubMed), PsychINFO and Cochrane‐CENTRAL was conducted. A quality assessment to estimate the risk of bias and a qualitative descriptive analysis were performed. The overall gathered evidence was graded.

Results

Ten randomized controlled trials and three observational studies thus in total 13 studies were included. Flossing was the targeted behaviour in ten studies. The target groups consisted of students, adolescents and dental patients. Overall, all nine HAPA constructs were used, but only one study used all HAPA constructs. Six studies presented the used behavioural change techniques according to the BCT taxonomy. Based on the number of the used constructs, only two studies were classified as HAPA intervention studies. The most frequently used constructs were action control as an intervention and behaviour as an outcome measure. The overall evidence was graded with moderate certainty.

Conclusion

In the majority of the studies, the targeted intervention was flossing and the population consisted of students, adolescents and dental patients. All studies used only a selection of the HAPA constructs. Therefore, only a minority of the studies can be considered real HAPA intervention studies.

1. INTRODUCTION

In dentistry, dental caries and periodontal disease are the most common diseases, according to the World Health Organization. ¹ An indispensable factor to reduce the development and progression of dental caries and periodontal diseases is controlling the dental plaque on the tooth surface through proper oral hygiene. Proper, self‐performed oral hygiene includes efficient twice‐daily tooth brushing with a fluoride‐containing toothpaste complemented by efficient interdental cleaning for at‐risk individuals. ² The patient's knowledge of how and why to maintain oral health as well as understanding the initiation and progression of dental caries and periodontal diseases is an essential factor to comply to preventive strategies to improve oral health. ³ Nevertheless, this knowledge does not necessary lead to active performance of desired behaviour. Dental care professionals (DCPs) should be able to provide knowledge, individual instruction and coaching to practice proper dental plaque control, to use fluoride and to reduce sugar intake. ² This enables patients to learn adequate oral hygiene skills from a DCP. Studies have proven that oral hygiene instructions are more effective if they are supplemented with motivational approaches. ²

Applying new or adjusted oral hygiene skills often requires a behavioural change, which can be difficult to achieve since patients may need to adjust their daily routines. For the change to be successful, first, an intention to change is necessary, and second, this intention must be translated into active performance of the new behaviour. Often, the behavioural change is not immediate but needs time and active repetition to be internalized and to become routine behaviour. ⁴ To establish behavioural change in oral health education, a variety of theories and models have been used. ⁵ , ⁶

One of the promising models is the Health Action Process Approach (HAPA), ⁷ which is aimed to overcome the ‘intention‐behaviour gap’. ⁸ It consists of two phases: the motivational phase (pre‐intentional phase) in which an intention to change behaviour is formed and the volition phase (post‐intentional phase) in which the patient is supported by a healthcare professional to implement and maintain the intended behaviour. ⁷ In the two phases of HAPA, being the motivational phase and the volitional phase, several constructs can be identified. The motivation phase comprises three social cognitive constructs that form the behavioural intention: ‘action self‐efficacy’ (people assess their belief in themselves to perform the behavioural change), ‘outcome expectancies’ (people consider which results to expect from the behavioural change) and ‘risk perceptions’ (people consider any negative consequences of the current behaviour). ⁷ , ⁹ The volitional phase comprises four constructs: ‘action planning’ (people make detailed plans on ‘when, where and how’ they will implement the change), ‘coping planning’ (people consider possible barriers and plan how to anticipate these events), ⁹ ‘coping self‐efficacy’ and ‘recovery self‐efficacy’ (people assess their own abilities to maintain or restart the new behaviour if a relapse occurs). The outcome of the HAPA model is a health behaviour. In oral health, behaviour is often also part of the intervention. For instance, 2 min of tooth brushing twice‐daily ¹⁰ , ¹¹ is the outcome behaviour, but training this behaviour is also an essential part of the intervention. This complexity indicates an urgent need to clearly define behaviour as an outcome of health or as a training behaviour as a part of the intervention.

The HAPA model has been used in several dentistry studies. A systematic overview of the application of the HAPA model in dentistry has not yet been published. The aim of this study is to systematically review the HAPA‐based studies in dentistry regarding the interventions (i.e. targeted oral health behaviours), the targeted group and the social cognitive constructs of the HAPA model used to change oral health behaviour or used as outcome measurements as well as to assess the clinical relevance of these studies.

2. MATERIALS AND METHODS

This systematic review was prepared in accordance with the Cochrane Handbook for Systematic Reviews of Interventions ¹² and in line with the ‘Preferred Reporting Items for Systematic Reviews and Meta‐Analyses: the PRISMA statement' (PRISMA), ¹³ ‘Meta‐analysis of Observational Studies in Epidemiology’ (MOOSE) ¹⁴ and the ‘Synthesis without Meta‐Analysis’ (SWiM) reporting guidelines. ¹⁵ The study protocol was approved by the ethics commission of the Academic Centre for Dentistry in Amsterdam (ACTA) for systematic reviews; the protocol number is 2021‐1‐4‐375. The researched protocol was registered at the international prospective register of systematic reviews (PROSPERO) under code CRD42022307982.

2.1. Focussed question

In dentistry, in order to change oral health behaviour what are the HAPA‐based target groups, what are the interventions and which constructs of the HAPA model are used?

The domain, determinant and outcome (DDO) strategy was used: studies in dentistry that used the HAPA model for an intervention (domain), by the use of the HAPA constructs, the group of participants as well as the targeted oral health behaviour (determinant) on the change oral health behaviour (outcomes).

2.2. Eligibility criteria

English‐language studies were eligible for inclusion if they met the following criteria:

1. Randomized clinical trial or observational study

2. Within dentistry (intervention or outcome measurement)

3. Participants were humans of all ages

4. Participants were a group

5. Intervention was a HAPA‐based instruction focussed on oral health behaviour with at least one social cognitive construct of the HAPA model

6. Outcome measurements were clinical oral health parameters, self‐reported behaviour or at least one social cognitive construct of the HAPA model

2.3. Search and selection strategy

A structured search was conducted in three electronic databases (the National Library of Medicine [MEDLINE‐PubMed], PsychINFO and Cochrane CENTRAL) from the study's inception through June 2022 to retrieve appropriate papers that answered the focussed question. Additionally, hand searching was conducted to screen the reference list of included studies. For details regarding the search terms, see Table 1. The retrieved studies were uploaded into Rayyan software ¹⁶ to check for duplicates and to screen and select the studies. The titles and abstracts were screened for inclusion criteria by two independent reviewers (ML and KvN). Titles and abstracts were categorized as ‘definitely eligible’, ‘definitely not eligible’ or ‘questionable’. If the abstract did not contain sufficient information to determine inclusion or exclusion, then the article or methodology was read in full. After the individual screening process, the search was unblinded and conflicts that were identified by Rayyan were resolved by two reviewers (ML and KvN), who discussed the studies. Full texts were retrieved and screened for suitability. After reading the full‐text papers, two reviewers (ML and KvN) discussed the eligibility of the studies based on the selection criteria. When the discussions on search and selection were inconclusive, a third independent reviewer (CvL) settled the disagreements. The studies that met all inclusion criteria were processed for data extraction.

TABLE 1.

Search string

((Schwarzer) OR ((HAPA) OR ([health action process approach]))) AND (((dentistry[MeSH Terms]) OR (dental)) OR (dent*)).

Note: The asterisk (*) was used as a truncation symbol.

2.4. Assessment of heterogeneity

Clinical heterogeneity was assessed for the diversity of the participants, the interventions (targeted oral health behaviour) and the social cognitive constructs used as outcome measurements. The methodological heterogeneity was assessed for the study designs, the social cognitive constructs used as interventions and the durations of the studies.

2.5. Data extraction analysis

Data from the papers that fulfilled all of the inclusion criteria were extracted in specially designed forms by two reviewers (ML and KvN). Additional disagreements were resolved by discussion to reach consensus. When these discussions were inconclusive, a third independent reviewer (CvL) settled the disagreements. Data were collected regarding the study design (publication year, study type, study duration, study setting and country), intervention (targeted oral health behaviour, control group and HAPA constructs), population characteristics (oral disease, sample size, gender and age), outcome characteristics (clinical parameters, self‐reported behaviour and HAPA constructs) and authors' conclusions. The outcome measurement behaviour was defined as the oral health behaviour performance in participants' daily lives, such as brushing and flossing. Additional data extraction included further outcome measurements and details regarding intervention delivery and identification of outcomes, as well as behavioural change techniques (BCTs) used. BCTs are defined as ‘an observable, replicable, and irreducible component of an intervention designed to alter or redirect causal processes that regulate behaviour; that is, a technique is proposed to be an “active ingredient” (e.g. feedback, self‐monitoring and reinforcement)’. ¹⁷ . If confusion regarding data existed, then authors were contacted to request additional information.

2.6. Strategy for quality and risk‐of‐bias assessments

The methodological qualities of the studies were scored using the quality assessment from the Cochrane Handbook and following the judgements of the algorithms. ¹⁸ To assess the risk of bias in randomized controlled trial (RCT) studies, the RoB2 tool ¹⁹ was used, and for the observational studies, the ROBINS‐I tool was used. ²⁰ These evaluations were performed independently by two of the three reviewers (ML, KvN and CvL) with the focus on the effect of assignment to the intervention at baseline. After the assessment, the two reviewers discussed their findings to reach agreements regarding conflicting assessments. The third reviewer was consulted when conflicts were not resolved.

2.7. Data synthesis

A quantitative data analysis was conducted based on the total number of occurrences, using a form that was specially designed for this purpose. The target group, target intervention and HAPA constructs were analysed quantitatively. A summary was performed to determine the percentage by which HAPA constructs were included separately for the interventions and the outcomes. An additional analysis was performed to determine whether a study could be considered a real HAPA study, based on Schwarzer and Hamilton's requirement of the presence of self‐efficacy and planning in the intervention as well as intention and behaviour as outcome measurements. ²¹ A descriptive qualitative data analysis was planned as a meta‐analysis does not suit the research question addressed.

2.8. Grading the quality of evidence

A modified method of grading, based on the Grading of Recommendations Assessment, Development and Evaluation (GRADE) ²² criteria, was used to rank the overall quality of evidence. Two reviewers (ML and KvN) rated the following aspects: risk of bias, inconsistency of results, indirectness of evidence, imprecision of data and publication bias regarding the different outcomes. Any disagreement between the reviewers was resolved after discussing their findings, and a third reviewer (DES) was consulted when necessary. The overall body of evidence is presented in Table 5.

TABLE 5.

Summary of findings of the body of evidence and estimating and grading the evidence profile

Determinants of quality	Results
Study design (Table 2, Figure 1)	RCT, observational and qualitative
Number of studies (Table 2, Figure 1)	16 (RCT: 9, observational: 6, qualitative 1)
Number of included participants	3709
Risk of Bias (Table S4 and Table S5)	RCT: Low‐High, observational: Moderate‐Serious, qualitative: moderate
Consistency	Rather inconsistent
Directness	Rather not generalizable
Precision	Imprecise
Reporting Bias	Possible
Certainty/ quality of evidence	Moderate
Strength and direction of the recommendation based on the quality, body and certainty of evidence	With moderate certainty HAPA‐based interventions in dentistry are evaluated mainly by the use of floss in students, adolescents and dental patients. All constructs of the HAPA model are evaluated, but not all constructs are used as a full set for defining the intervention nor studied as outcome measurement

3. RESULTS

3.1. Study selection

The search revealed, after removing duplicates, 267 unique studies (Figure 1). First, 16 studies were selected for full‐text eligibility screening, whereafter seven studies were excluded, of which three studies were not an intervention study ⁴ , ²³ , ²⁴ and four studies did not use any HAPA construct in the intervention. ²⁵ , ²⁶ , ²⁷ , ²⁸ Consequently, 9 studies were preliminary included in this review (I, ²⁹ II, ³⁰ III, ³¹ IV, ³² V, ³³ VI, ³⁴ VII, ³⁵ XI ³⁶ and XII ³⁷ ). After screening the reference lists of the included studies, four additional studies could be included (VIII, ³⁸ IX, ³⁹ X ⁴⁰ and XIII ⁴¹ ). Consequently, the final selection included 13 studies presenting 14 intervention groups, as Study VI ³⁴ presented two intervention groups. Table 2 presents an overview of the included studies and Table S2 presents an overview of the excluded studies.

FIGURE 1.

Overview of the selection procedure of the articles

TABLE 2.

Characteristics of the included studies

Author, year; Design; Duration of the study; Risk of bias (for details, see Table S4 and S5)	Study setting, country; Group characteristics; N, gender (F/M); Age: Mean (SD) years, range	Targeted behaviour; Intervention	HAPA constructsa used in the intervention, per phase (for details, see Table S3 and S7)	Control	HAPA constructsa as outcome measures, (for details see Table S3 and S7) Other outcome measures	Conclusion of the original Authors
I30 Lhakhang et al. (2016) RCT 3weeks RoB: Some concerns	Dental college and hospitals, India Patients >18 years clinically diagnosed with periodontal disease N = 112 F/M: NI Age b : 27.1 Range: NI Group intervention: N = 55, F/M = 34/21 Age: 31.6 (14.1) Range: NI Group control: N = 58, F/M = 42/16 Age: 22.8 (9.8) Range: NI	Dental flossing Intervention package with self‐management cues and incentives (free dental care)	Motivational phase: aSE Volitional phase: AP, AC BCT's:♦ 1.1; 1.4; 2.3; 4.1; 5.1; 5.7; 15.1 ♦All BCTs were not in the article but given by author upon request	Questionnaire only	Self‐reported questionnaire: BEH, INT, aSE c , cSE c	Sign increase in flossing Indirect effect on flossing via self‐efficacy and intention The effect on flossing was higher in women than in men
II31 Scheerman et al. (2020) Cluster RCT 3‐arm: 1:1:1 6 months (1& 6 months after baseline) RoB: Some concerns	30 high schools, Iran Adolescents N = 791, F/M = 332/45Age: 15.5 (1.3) Range: 12–17 Group intervention: Group A: adolescents N = 253 F/M:101/152 Age:15.2 (1.0) Range: NI Group control Positive control Adolescents & mother N = 260, F/M:112/148 Age:15.3 (1.6) Range: NI Negative control N = 278, F/M:119/159 Age: 15.4 (1.3) Range: NI	Tooth brushing Group A Online platform to deliver information, making plans, register behaviour and sending reinforcements	Motivational phase: OE, RP Volitional phase: AP, CP, AC BCT: NI	1.A&M: Same as group A + online platform to coach mothers to encourage their child 2. Questionnaire only	Self‐reported questionnaire: BEH, INT, OE, RP, aSE AP, CP, AC d Perceived social support, OHRQoL Clinical examination by two trained dental professionals: Parameters for dental plaque and periodontal disease	Short‐ and long‐term effects on outcome measures in the intervention groups. Online social media platform involving mothers, in addition to adolescents, further improve the effectiveness of tooth brushing
III32 Gholami et al. (2015) Cluster RCT 4weeks RoB: Some concerns	Schools, Iran Girls attending grade 5–8 N = 166, F/M:100/0 Age: 12.5 (1.1) Range:11–15 Group intervention (N = 69) Age & range: NI Group control (N = 97) Age & range: NI	Dental flossing Intervention package, with exercising flossing and planning	Motivational phase: aSE Volitional phase: AP, CP BCT: 6.2, 1.4,15.4,1.2	Questionnaire only	Self‐reported questionnaire: BEH, INT, aSE c AP, CP	Increase in dental flossing in the intervention group. Intention and self‐efficacy mediate between the intervention and dental flossing
IV33 Lhakhang et al. (2015) Cluster Cross‐over RCT Sequential 34 (17+17) days RoB: Low	Student's residence, India University students N = 205, F/M: 106/99 Age: 20.7 (1.59) Range: 18–26 years Group sequence 1 N = 94, F/M = 49/45 Age:19.8 (1.3) Range: NI Group sequence 2 N = 111, F/M = 57/54 Age: 21.5 (1.4) Range: NI	Dental flossing Motivational intervention package with outcome perspectives and goal setting + Self‐regulatory intervention package with planning in monitoring behaviour	Motivational phase: INT, OE, RP, aSE Volitional phase: cSE, AP, CP, AC BCT: 1,2,4,5,8,10,11	Self‐regulatory + motivational intervention	Self‐reported questionnaire: BEH, aSE c , e cSE c , AP f , CP f , AC	Both sequences increased dental flossing behaviour, ‘self‐efficacy’, ‘action control’ The increase is higher in the group that received SR‐MI than in the group that received MI‐SR Only motivational intervention is not enough, a combination with self‐regulation is better
V34 Zhou et al. (2015) RCT 1 month RoB: Some concerns	University, China University students N = 215 (N = 284, F/M b : 37/178 minus n = 69 drop out) Age: NI Range: 18–29 years Group: self‐regulation (incl. educational) N = 127 Age & range: NI Group: educational N = 88 Age & Range: NI	Dental flossing Educational intervention package with outcome perspectives and goal setting + Self‐regulatory intervention with planning and monitoring	Motivational phase: INT, OE, RP Volitional phase: AP, CP, AC BCT's: 1.1, 1.2,1,4,2.3, 4.1,5.1	Educational intervention with outcome perspectives and goal setting	Self‐reported questionnaire: BEH, aSE e AP f , CP f , AC	Increase in oral self‐care in the self‐regulation group with higher levels of planning and AC than in the educational group
VI35 Schwarzer et al. (2015) RCT 3 arm 1:1:0,5 3 weeks RoB: Some concerns	University, Poland University students N = 287, F/M = 183/104 Age: 21.4 (1.6) Range: 19–26 years Group intervention N = 106 Age & range: NI Group control N = 114 Age & range: NI Group questionnaire only N = 67 Age & range: NI	Dental flossing Intervention package with information planning and monitoring	Motivational phase: OE, RP, aSE Volitional phase: cSE, AP, CP, AC BCT: 1.4, 2.3,15	1.Intervention package with information and outcome perspectives 2. Questionnaire only	BEH cSE, AC d	A short intervention can change the mindset of the participants. The interval was too short for a change is the floss frequentation
VII36 Wu et al. (2022) RCT 12 weeks RoB Some concerns	Orthodontic department of Stomatological university hospital, China Adults 17–29 years with fixed orthodontic appliances N = 44 Age:17–44, range: 18–29 Group intervention N = 22, F/M:12/10 Range: 18–29 Group Control N = 22, F/M:11/11 Range: 18–28	Oral hygiene behaviour (Primary: brushing, using mouthwash and dental floss. Secondary: interdental brushes, oral irrigator or dental floss in combination and mouthwash) Online mini‐program positive reinforcement using photographs and personalised notification	Motivational phase: Volitional phase: AC d	Questionnaire only	Self‐reported questionnaire: BEH, OE, RP, INT, aSE, cSE h , AP, CP, AC Social influences Clinical examination by two trained and calibrated clinical examiners: Parameters for dental plaque and periodontal disease	In both groups, the dental plaque reduced. The mini‐program, more than care as usual, reduced dental plaque and increased OE, AC and social influences
VIII39 Scheerman et al. (2020)2 RCT 12weeks RoB: Some concerns	Orthodontic clinics, the Netherlands Adolescents 12–16 years with fixed orthodontic appliances N = 132, F/M:73/59 Age: NI, Range: NI Group intervention N = 67, F/M:41/26 Age:13.2 (1.0) Range: NI Group control N = 65, F/m:32/33 Age:13.5 (1,0) Range: NI	Oral health performance App using selfies and positive reinforcements	Motivational phase: INT Volitional phase: AP, CP, AC BCT: i	Questionnaire only	Self‐reported questionnaire: OE, RP, aSE, INT, cSE h , j , AP,CP,AC, BEH Clinical examination by two trained and calibrated clinical examiners: Parameters for dental plaque and periodontal disease	The White Teeth app was associated with significant reduction in gingival bleeding at 6wks and dental plaque at 12 weeks. Although the app was not effective in changing tooth brushing frequency and duration, the decrease in dental plaque reflects a change in brushing pattern. At both follow‐ups, the app was also effective in changing CP regarding tooth brushing
IX40 Pakpour et al. (2016) Cluster RCT 6 months RoB: High	48 secondary schools, Iran, Adolescents N = 1158, F Range: NI	Tooth brushing Training tooth brushing and using calendar Implementation group: planning if‐then format	Motivational phase: Volitional phase: AP, AC	General planning: planning when, where, after what	Self‐reported questionnaire: BEH, INT, AP, AC d Perceived behavioural control QoL Clinical examination by two trained dentists: Parameters for dental plaque and periodontal disease	Although planning and implementation intention are effective in increasing the target behaviour (compared to active control), additional intervention components might be needed in order to achieve the recommended level of behaviour performance. Implementation intervention (if‐then format) is more effective than general planning
X41 Schüz et al. (2009)1 RCT 8 weeks BoB:High	University, Germany Visitors at open day university, >18 years N = 194, F/M:132/62 Age: 33.6 (13.5) Range: 18–71	Dental flossing Training behaviour and dental floss samples. Making action plans	Motivational phase: Volitional phase: AP	Questionnaire and dental floss samples	Self‐reported questionnaire: BEH Acceptance (adherence) Mindset	Action planning improved dental flossing compared with only flossing instructions and dental floss samples. The effects of planning are stronger in individuals with an implemental mindset (compared with deliberative mindset)
XI37 Schüz et al. (2007) observational 6 weeks RoB: Serious	University, Germany Undergraduate psychology and educational science students N = 151, F/M:122/29 Age: 25.2 (7.0) Range: NI	Dental flossing Intervention package with training behaviour and monitoring	Motivational phase: Volitional phase: AC	NA	Self‐reported questionnaire: BEH, INT AC g Behavioural stage BEH: Amount of unused dental floss	Changes in action control enhance flossing behaviour in volitional participants. These changes, intentions and behavioural stage at T1 are predictors of Time 3 flossing
XII38 Araújo et al. (2020) Observational 4 months (2 weeks & 4months) RoB: Serious	Two private dental clinics, Portugal Patients >18 years, ≥20 teeth, ≥5 teeth per quadrant, with gingivitis N = 201, F/M: 114/87 Age: 38.6 (12.5) Range: 18–75 years	Dental flossing or using interdental brushes Training behaviour	Motivational phase: INT	NA	Self‐reported questionnaire: BEH = brushing, BEH = flossing, aSE, INT, cSE h , j , CP, AC	Intention alone was not sufficient to predict oral health behaviours. Intention proved to be a predictor for coping planning and action control
XIII42 Suresh et al. (2012) Observational 4 weeks RoB: Serious	Dental clinic, Iraq Dental patients, >18 years, with at least 20 standing teeth N = 53 Motivational stage N = 21, F/M:13/18 Age:32.7 (8.1) Range: NI Volitional stage N = 32, F/M:20/22 Age:34.4 (6.3) Range: NI	Dental flossing Dental flossing calendar Training behaviour	Motivational phase: Volitional phase: AC	NA	Self‐reported questionnaire: BEH Behavioural stage Clinical examinations Parameters for dental plaque and periodontal disease Residual floss	A simple self‐monitoring intervention improves dental flossing and reduced plaque and bleeding scores, regardless of the behavioural stage of change

Abbreviations: AC, action control; AP, action planning; aSE, action self‐efficacy; BCT, Behavioural change technique¹⁷ (BCT); BEH, behaviour; CP, coping planning; cSE, coping self‐efficacy; F, female; HAPA, health action process approach; INT, Intention; M, male; NA, Not applicable; NI, unknown/unclear; OE, outcome expectancies; OHRQoL, oral health related quality of life; RP, risk perception.

^a HAPA constructs defined by the authors of this review.

^b Calculated by the authors of this review.

^c Defined by the original author as ‘self‐ efficacy’.

^d Defined by the original author as ‘self‐monitoring’.

^e Defined by the original author as ‘task self‐efficacy’.

^f Defined by the original author as ‘planning’.

^g Defined by the original authors as items on ‘self‐monitoring’, ‘awareness of standards’ and ‘self‐regulation’.

^h Defined by the original authors as ‘maintaining self‐efficacy’.

ⁱ Providing information on oral health consequences and demonstrating the desired behaviour, goal setting, implementation intentions, behavioural goal reminders, self‐monitoring of behaviour, practical support, self‐monitoring of behavioural outcomes, coping planning.

^j Defined by the original authors as ‘recovery self‐efficacy’.

3.2. Heterogeneity

3.2.1. Study characteristics

The designs of the included studies were RCT (n = 10, I, ²⁹ II, ³⁰ III, ³¹ IV, ³²  V, ³³ VI, ³⁴ VII, ³⁵ VIII, ³⁸ IX ³⁹ and X ⁴⁰ ) and observational (n = 3, XI, ³⁶ XII ³⁷ and XIII ⁴¹ ). It comprises details on the study design, participant demographics and HAPA constructs and authors conclusions. An overview of the questions sent to authors to request additional information is presented in Online Supplementary Table S1.

3.2.2. Methods of outcome measurements

All studies used questionnaires with Likert scale answering options to measure the HAPA constructs and open‐ended questions to measure the targeted oral health behaviour (e.g. ‘During the last week, I have flossed my teeth… times per day’). These 13 studies used eight differently framed open‐ended questions regarding the targeted oral health behaviour. Likewise, the questions used to measure the HAPA constructs differed between the studies in the number of questions per construct (from one to seven items), the range of the Likert scales (4‐ to 7‐point scales) and the formulation and sentence structures, for details see Table S3. In nine studies, details regarding the origin of the questions were included (II, ³⁰ V, ³³ VI, ³⁴ VII, ³⁵ VIII, ³⁸ IX, ³⁹ X, ⁴⁰ XI ³⁶ and XII ³⁷ ), and nine studies (II, ³⁰ III, ³¹ V, ³³ VI, ³⁴ VIII, ³⁸ IX, ³⁹ X, ⁴⁰ XI ³⁶ and XII ²⁷ ) mentioned the validity of some of the questions they used. Five studies (II, ³⁰ VII, ³⁵ VIII, ³⁸ IX ³⁹ and XIII ⁴¹ ) used clinical parameters to assess behaviour.

3.3. Risk‐of‐bias assessments

The results of the risk‐of‐bias analysis are presented in Table 2 (for details, see Table S4 for RCTs and Table S5 for observational studies). Overall, one RCT study had a low risk of bias (IV ³² ), seven RCT studies had some concerns (I, ²⁹ II, ³⁰ III, ³¹  V, ³³ VI, ³⁴ VII ³⁵ and VIII ³⁸ ), and two RCTs had high risk of bias (IX ³⁹ and X ⁴⁰ ). The three observational studies (XI, ³⁶ XII ³⁷ and XIII ⁴¹ ) had a serious risk of bias.

3.4. Study outcome results

3.4.1. The intervention: Targeted oral health behaviour

Overall, eight studies targeted only dental flossing as the oral health behaviour (I, ²⁹ III, ³¹ IV, ³² V, ³³ VI, ³⁴ X, ⁴⁰ XI ³⁶ and XIII ⁴¹ ). Two studies concentrated on tooth brushing (II ³⁰ and IX ³⁹ ), one study focussed on tooth brushing or dental flossing (XII ³⁷ ), one study focussed on tooth brushing, using a mouth wash and using floss, interdental brushes or an oral irrigator (VII ³⁵ ), and one study centred on non‐specified oral hygiene measures (VIII ³⁸ ). See Table 2 for more details.

3.4.2. The target groups

The participants were non‐dental students recruited at universities (IV, ³² V, ³³ VI ³⁴ and XI ³⁶ ), adolescents recruited at high schools (II, ³⁰ III ³¹ and IX ³⁹ ), adolescents recruited at orthodontic clinics (VII, ³⁵ and VIII ³⁸ ), and patients recruited at dental practices (I, ²⁹ XII ³⁷ and XIII ⁴¹ ) and visitors at an open day at a university (X ⁴⁰ ). In some studies, the patients were diagnosed with periodontal disease (I ²⁹ ) or gingivitis (XII ³⁷ ); see Table 2.

3.4.3. The HAPA constructs as interventions and outcome measurements

The studies used a variety of HAPA constructs in their interventions as well as outcome measurements. The number of HAPA constructs used ranged from one to nine. One of the studies ³² included all nine constructs from the HAPA model in the intervention. The reasons for using a set of specific HAPA constructs could be retrieved from the rationale for each study.

Action control (n = 10; I, ²⁹ II, ³⁰ IV, ³² V, ³³ VI, ³⁴ VII, ³⁵ VIII, ³⁸ IX, ³⁹ XI ³⁶ and XIII ⁴¹ ) was the most frequently used construct in the intervention. Action planning was used in nine studies (I, ²⁹ II, ³⁰ III, ³¹ IV, ³² V, ³³ VIII ³⁸ VIII, ³⁸ IX ³⁹ and X ⁴⁰ ), and coping planning was used in six studies (II, ³⁰ III, ³¹ IV, ³² V, ³³ VI ³⁴ and VIII ³⁸ ). Four studies (I, ²⁹ III, ³¹ IV ³² and VI ³⁴ ) used action self‐efficacy, and two studies (IV ³² and VI ³⁴ ) used coping self‐efficacy. Four studies used intention (IV, ³² V, ³³ VIII ³⁸ and XII ³⁷ ). Four studies (II, ³⁰ IV, ³²  V ³³ and VI ³⁴ ) used outcome expectancies and risk perceptions in one of their intervention groups. Six studies (I, ²⁹ III, ³¹ IV, ³² V, ³³ VI ³⁴ and VIII ³⁸ ) presented BCTs ¹⁷ to formulate the behavioural change technique they used in their intervention. An overview of the HAPA constructs and BCTs used in the interventions is presented in Table 3. An overview of the BCTs per construct is presented in Table S6.

TABLE 3.

Overview of the HAPA constructs used in the intervention

			Motivational phase					Volitional phase
	Study/Construct	Intervention groups	INT	OE	RP	aSE	cSE	AP	CP	AC	Original Authors	BCT	Total	Includes SE and Planning
I	Lhakhang et al. (2016)					x*		x		x	SR	♦1.1/1.4/2.3/4.1/5.1/5.7/15.1		3	+
II	Scheerman et al. (2020)	1 and 2		x	x			x	x	x		NI		5	−
III	Gholami et al. (2015)					x		x	x			6.2/1.4/15.4/1.2/		3	+
IV	Lhakhang et al. (2015)	1 and 2	x	x	x	x	x	x	x	x		8/1/2/4/10/5/11		8	+
V	Zhou et al. (2015)	1 and 2	x	x	x			x	x	x		1.1/4.1/5.1/1.2/1.4/2.3		6	−
											SM
VI	Schwarzer et al. (2015)	1				x	x	x	x	x		15/1.4/2.3		4	+
		2		x	x									1
VII	Wu et al. (2022)									x				1	−
VIII	Scheerman et al. (2020) 2		x					x	x	x		BCT: a		4	−
IX	Pakpour et al. (2016)							x		x				2	−
X	Schüz et al. (2009) 1							x						1	−
XI	Schüz et al. (2007)									x	SM			1	−
XII	Araújo et al. (2020)		x											2	−
XIII	Suresh et al. (2012)									x				1	−
	TOTAL		4 (31%)	4 (31%)	4 (31%)	4 (31%)	2 (15%)	9 (69%)	6 (46%)	10 (77%)					4

Note: ♦information obtained from the authors upon request.

Abbreviations: TRN BEH, trained behaviour; INT, intention; OE, outcome expectancies; RP, risk perceptions; aSE, action self‐efficacy; cSE, coping self‐efficacy; AP, action planning; CP, coping planning; AC, action control.

1 = intervention group, 2 = positive control group.

^a Providing information on oral health consequences and demonstrating the desired behaviour, goal setting, implementation intentions, behavioural goal reminders, self‐monitoring of behaviour, practical support, self‐monitoring of behavioural outcomes and coping planning.

^bthe authors mention SE, but it is not clear whether it is aSE, cSe.

An overview of the HAPA constructs used as outcome measurements is presented in Table 4. Behaviour was the most assessed construct (I, ²⁹ II, ³⁰ III, ³¹ IV, ³² V, ³³ VI, ³⁴ VII, ³⁵ VIII, ³⁸ IX, ³⁹ X, ⁴⁰ XI, ³⁶ XII ³⁷ and XIII ⁴¹ ). Action control was assessed in nine studies (II, ³⁰ IV, ³² V, ³³ VI, ³⁴ VII, ³⁵ VIII, ³⁸ IX, ³⁹ XI ³⁶ and XII ³⁷ ). Nine studies assessed at least one type of self‐efficacy (I, ²⁹ II, ³⁰ III, ³¹ IV, ³² V, ³³ VI, ³⁴ VII, ³⁵ VIII ³⁸ and XII ³⁷ ). More specifically, eight studies assessed action self‐efficacy (I, ²⁹ II, ³⁰ III, ³¹ IV, ³² V, ³³ VII, ³⁵ VIII ³⁸ and XII ³⁷ ) and six studies assessed coping self‐efficacy (I, ²⁹ IV, ³² VI, ³⁴ VII, ³⁵ VIII ³⁸ and XII ³⁷ ). Eight studies assessed intention (I, ²⁹ II, ³⁰ III, ³¹ VII, ³⁵ VIII, ³⁸ IX, ³⁹ XI ³⁶ and XII ³⁷ ). Action planning was assessed in seven studies (II, ³⁰ III, ³¹ IV, ³² V, ³³ VII, ³⁵ VIII ³⁸ and IX ³⁹ ). Coping planning was assessed in seven studies (II, ³⁰ III, ³¹ IV, ³² V, ³³ VII, ³⁵ VIII ³⁸ and XII ³⁷ ). Three studies (II, ³⁰ VII ³⁵ and VIII ³⁸ ) assessed outcome expectancies and risk perceptions.

TABLE 4.

Overview of the HAPA constructs used as outcome measures

	Study/Construct	INT	OE	RP	aSE	cSE	AP	CP	AC	BEH	Authors	Total	Included INT and BEH
I	Lhakhang et al. (2016)	x			x	x				x		4	+
II	Scheerman et al. (2020)	x	x	x	x		x	x	x	x	SE	8	+
III	Gholami et al. (2015)	x			x		x	x		x		5	+
IV	Lhakhang et al. (2015)				x	x	x	x	x	x	SE(=tSE + cSE)Planning (AP + CP)	6	−
V	Zhou et al. (2015)				x		x	x	x	x	SE(=tSE)Planning (AP + CP)	5	−
VI	Schwarzer et al. (2015)					x			x	x		3	−
VII	Wu et al. (2022)	x	x	x	x	x	x	x	x	x		9	+
VIII	Scheerman et al. (2020) 2	x	x	x	x	x	x	x	x	x	mSE, rSE	9	+
IX	Pakpour et al. (2016)	x					x		x	x		4	+
X	Schüz et al. (2009) 1									x		1	−
XI	Schüz et al. (2007)	x							x	x		3	−
XII	Araújo et al. (2020)	x			x	x		x	x	x		6	+
XIII	Suresh et al. (2012)									x			−
	TOTAL	8(62%)	3(23%)	3(23%)	8(62%)	6(46%)	7(54%)	7(54%)	9(69%)	13(100%)			7

Abbreviations: BEH, behaviour; INT, intention; OE, outcome expectancies; RP, risk perceptions; aSE, action self‐efficacy; cSE, coping self‐efficacy; AP, action planning; CP, coping planning; AC, action control.

Two studies (I ²⁹ and III ³¹ ) used a combination of one type of self‐efficacy and one type of planning to mediate between intention and behavioural outcomes; as described previously, they could therefore be regarded as real HAPA studies as defined by Schwarzer and Hamilton; ²¹ see Table S7.

3.5. Grading the body of evidence

Table 5 summarizes the findings of the body of evidence and estimating and grading of the included studies. It summarizes the strength and direction of the recommendation based on the quality, body and certainty of evidence. Overall, with moderate certainty HAPA‐based interventions in dentistry are evaluated mainly by the use of floss in students, adolescents and dental patients. All constructs in the HAPA model were evaluated, but not all constructs were used as a full set to define the intervention or studied as an outcome measurement.

4. DISCUSSION

The aim of this study was to systematically review the HAPA‐based dentistry studies regarding targeted oral health behaviours (interventions), targeted groups and the social cognitive constructs of the HAPA model that were targeted in the interventions or measured as outcomes. The majority of the studies used flossing as the targeted intervention. In all 13 included studies, the targeted population were students, adolescents or adults, 3709 in total. All HAPA constructs were used, but only one of the studies used all of the constructs. In the intervention phase, action control was the focus, and as an outcome measurement, behaviour was mostly studied.

4.1. HAPA constructs in oral health research

From a behavioural scientific point of view, ‘oral health behaviour’ is a very broad and complex concept. Optimal self‐care is not simply a matter of daily removal of dental plaque by ‘just tooth brushing and flossing’, as tooth brushing by itself is often not done effectively on a daily base. ⁴² Determinants of ⁴³ and promoting ⁴⁴ oral hygiene behaviour are described in the scientific literature, as oral hygiene is a collection of unique behaviours. ⁴⁵ The Stages of Change model by DiClemente and Prochaska is one of the most widely adopted models for behavioural change. This is also called the Transtheoretical Model (TTM), and there is an overlap with HAPA. Key for HAPA over other theories is that HAPA contains action planning and coping planning.

Schwarzer and Hamilton state that a study is considered a HAPA study if it reports a combination of one type of self‐efficacy and one type of planning that mediates between intentions and behavioural outcomes. ²¹ Using this definition, only two of the included studies could be defined as real HAPA studies. ²⁹ , ³¹ The present study challenges this statement to use any construct in the intervention and the outcome, as several studies are considered as HAPA while using other constructs.

The HAPA model is an open‐architecture framework that allows the use of only a part of the model's constructs. ⁴⁶ The HAPA intervention can be delivered in a stage‐matched format, meaning that participants can receive the intervention that fits their degree of self‐efficacy, planning and action control. ⁴⁶ One of the included studies showed that a volitional intervention using action control increased behaviour regardless of a person's stage. ⁴¹ In the present review, the interventions mainly focussed on action control, action planning, coping planning as volitional constructs, and on intention, outcome expectancies, risk perceptions and action self‐efficacy, each of which was targeted in four studies, as motivational constructs. Four studies targeted one of the self‐efficacy constructs and one of the planning constructs in the intervention, a prerequisite to be a real HAPA intervention. For outcomes measurements, behaviour was the most commonly used outcome measurement, followed by action control, intention and action self‐efficacy. Eight studies used both intention and behaviour as outcome measurements. According to the original Schwarzer and Hamilton definition, one type of self‐efficacy and one type of planning to mediate between intention and behavioural outcomes are needed to consider a study a real HAPA study. ²¹ Only two ²⁹ , ³¹ of the 13 included studies met these criteria.

4.2. Behavioural change techniques

The HAPA interventions can be designed using BCTs, which were developed to specify, evaluate and implement behavioural change interventions and to facilitate the comparison of the interventions. ¹⁷ BCTs are usually selected on the basis of the theoretical constructs they are intended to target. ⁴⁷ Only six of the included studies reported which BCTs were used. ²⁹ , ³² , ³³ , ³⁴ , ³⁸ These were all RCTs. In these studies, the use of BCTs eases comparison of the designs of the interventions between the treatment groups. Probably as a result of using BCTs, the HAPA constructs were more explicitly designed in the included RCTs than in the observational studies. BCTs may not have been reported in the observational studies because these studies have targeted fewer HAPA constructs in the intervention. Specifically, only two observational studies ³⁶ , ⁴¹ used action control, and only one study ³⁷ used intention.

In the present review, various BCTs were used in the interventions. All authors but one ²⁹ linked a BCT to a construct. ³² , ³³ , ³⁴ , ³⁸ The HAPA constructs and BCTs are, however, not synonymous, which indicates that a direct translation or transition of the BCT taxonomy to the HAPA constructs or vice versa is difficult. Nevertheless, reporting both HAPA constructs and BCTs can easily reveal the differences and similarities in study designs. Therefore, the recommendation for further studies is to report both HAPA constructs and BCTs and to evaluate the HAPA constructs as well as the BCT taxonomy. Additionally, there seems to be room for a systematic evaluation of BCTs in dentistry. In the present review, BCTs were not an initial parameter that was considered as an inclusion criterion.

4.3. Study designs and methodology

The populations of the included studies varied, from students to adolescents, adults, dental practice patients, dentally sound patients and patients who were diagnosed with periodontitis. Each targeted intervention should be aligned with the population. Patients who are diagnosed with an oral disease are an appropriate target group for behavioural change interventions, because their health is expected to improve as a result of behavioural changes. These patients are expected to have a higher risk perception and to be more focussed on the positive outcome expectancies of the new behaviour. Consequently, they may be more motivated towards behavioural change than healthy participants. ⁴⁸ The majority of the included studies, however, engaged healthy patients—often students—with an insignificant need for behavioural change. Furthermore, new health behaviour is generally more easily adopted by people who have advanced educations. ³⁶ Therefore, it is questionable whether healthy students are an appropriate target group.

Dental flossing was the most commonly targeted oral health behaviour. However, floss as a targeted intervention is questionable, as the use of floss is not proven to be effective in improving oral health. ⁴⁹ , ⁵⁰ , ⁵¹ , ⁵² , ⁵³ In addition to tooth brushing, other interdental cleaning tools, such as interdental brushes, ⁵⁰ , ⁵⁴ , ⁵⁵ woodsticks, ⁵⁶ oral irrigators ⁵⁴ , ⁵⁵ , ⁵⁷ and rubber interdental bristle cleaners, ⁵⁸ can have a positive effect on oral health. It is important that a targeted intervention by itself is effective, and HAPA studies using dental floss may not generate an improvement in oral health, which may interfere with HAPA constructs, such as outcome expectancies, risk perceptions and self‐efficacy. Notably, in contrast to the scientific evidence, flossing is still believed by the public to be effective in improving oral health. This positive framing of flossing can increase outcome expactancies, which are, according to the HAPA model, reflected in patients' intentions and thereby their behaviour. Furthermore, it is a waste that money is invested in studies where dental floss is an intervention while it is generally known for its limited clinical relevance and scientific evidence. Dental care professionals should follow the rules of evidence‐based practice and should advise other tools than dental floss.

Normally, the intervention needs ample time to turn into a long‐lasting behavioural change. ⁵⁹ In addition, the follow‐up must be as long as needed to evaluate any effect of the behavioural change. For instance, to evaluate the gum‐bleeding tendency only a few weeks are needed, while evaluating the reduction in caries is a matter of years. ² , ¹¹ Little is known about the substantivity of and adherence to the new habit over time ⁶⁰ in particular after the 10 weeks. Nine out of the thirteen included studies had a follow‐up period that was less than the 10 weeks which may be needed for habit formation. ⁵⁹ Therefore, the clinical relevance of the included studies can be doubted. Thus, there is a need for studies regarding the time needed for a behavioural change to become a habit, ⁴ specifically in dental care. Thus, longer follow‐up studies are a direction for further research. There is a need for minimal 10 weeks in order to establish the behaviour change. An effect on the oral health outcome follow‐up time differs per targeted outcome.

4.4. Limitations and recommendations

‐Studies may have been missed if they used HAPA constructs but had not labelled them as such in the original papers.

‐For systematic reviews that lack data amenable to meta‐analysis, alternative synthesis methods are commonly used. The SWiM guideline has been developed to guide clear reporting in reviews in which alternative synthesis methods are used. This applied to the present manuscript.

‐The original HAPA model ⁷ consists of seven constructs; later, Schwarzer and Hamilton stated that only four constructs are enough to be considered as real HAPA. ²¹ The Schwarzer & Hamilton statement lacks a psychological and behavioural scientific fundament. There is a need for further research on this important aspect. The present review found in majority flossing as parameter for oral healht behaviour. Aspects such as dental visits, dental fear, smoking cessation and diet can, however, also be considered for future studies.

5. CONCLUSION

Based on 13 studies, the HAPA model was evaluated to assess behavioural changes in oral health. With moderate certainty, HAPA‐based interventions in dentistry are evaluated mainly by the use of floss in students, adolescents and dental patients. All constructs of the HAPA model were evaluated, but only one study used all constructs as a full set to define the intervention, while no study used all constructs to measure outcomes. There is an urgent need to align the target population, the targeted intervention, the targeted outcome and the HAPA constructs to be used. Additionally, the BCT taxonomy should be combined with the HAPA intervention. Lastly, the follow‐up time of interventions could be extended to 10 weeks at least to create a behavioural change and often longer to assess its effects on oral health outcomes.

6. CLINICAL RELEVANCE

6.1. Scientific rationale for the study

The HAPA model is used to evaluate changes in oral health behaviour.

6.2. Principal findings

HAPA interventions in dentistry are mainly evaluated by the use of floss in students, adolescents and dental patients. All constructs of the HAPA model are evaluated, but not all constructs are used as a full set to define the intervention or studied as an outcome measurement.

6.3. Practical implications and suggestions for future studies

There is an urgent need to align the target population, the targeted intervention, the targeted outcome and the HAPA constructs to be used. Additionally, the BCT taxonomy should be combined with the HAPA intervention.

AUTHOR CONTRIBUTION

All authors gave final approval and agreed to be accountable for all aspects of the work ensuring integrity and accuracy. KAVN contributed to the conception and design, search and selection, analysis and interpretation, and drafted the final manuscript. CVL contributed to the conception and design, study selection, analysis and interpretation, and critically revised the manuscript. MFL contributed to the design, search and selection, analysis and interpretation, and drafted the preliminary manuscript. DES contributed to the conception and design, analysis and interpretation, and critically revised manuscript.

FUNDING INFORMATION

This research received no specific grant from any funding agency in the public, commercial or not‐for‐profit sectors. For this study, no funding was accepted, except for support from the listed institution.

This study was in part prepared as obligation of third author Luteijn to fulfil the requirements of the ACTA master programme of Dentistry.

CONFLICT OF INTEREST

The authors declare that they have no conflicts of interest.

ETHICS STATEMENT

Ethics approval was not required, and the protocol was registered at ACTA IRB by protocol number 2021‐1‐4‐375. The researched protocol was registered at the international prospective register of systematic reviews (PROSPERO) under ceode CRD42022307982.

Supporting information

Table S1: Overview of the questions send out to the original authors

Table S2: Oerview of the excluded studies

Table S3: Details on how the intervention and control were delivered and by whom, and details on how the HAPA constructs were measured

Table S4: Risk of bias in RCT (RoB2)

Table S5: Risk of bias in the observational and qualitative studies (ROBINS‐I)

Table S6: Overview of the HAPA constructs used as intervention and the behavioural change techniques^a per construct

Table S7: Overview of real HAPA studies: self‐efficacy and planning in the intervention as mediators between intention and behaviour as outcome measures

Figure S1: The (HAPA) (Adapted from Zhang et al., 2019)

van Nes KA, van Loveren C, Luteijn MF, Slot DE. Health action process approach in oral health behaviour: Target interventions, constructs and groups—A systematic review. Int J Dent Hygiene. 2023;21:59‐76. doi: 10.1111/idh.12628

DATA AVAILABILITY STATEMENT

Data derived from public domain resources. The data (the 13 included studies) that support the findings of this study are available from search databases the National Library of Medicine (MEDLINE‐PubMed), PsychINFO and Cochrane‐CENTRAL. These data were derived from resources available in original papers that are published in the public domain.