*Article* **Does Instruction of Oral Health Behavior for Workers Improve Work Performance? —Quasi-Randomized Trial**

**Naoki Toyama 1, Ayano Taniguchi-Tabata 2,\*, Nanami Sawada 1, Yoshio Sugiura 1, Daiki Fukuhara 1, Yoko Uchida 1, Hisataka Miyai 1, Aya Yokoi 1, Shinsuke Mizutani 3,4, Daisuke Ekuni <sup>1</sup> and Manabu Morita <sup>1</sup>**


Received: 31 October 2018; Accepted: 22 November 2018; Published: 24 November 2018

**Abstract:** Oral disease can cause economic loss due to impaired work performance. Therefore, improvement of oral health status and prevention of oral disease is essential among workers. The purpose of this study was to investigate whether oral health-related behavioral modification intervention influences work performance or improves oral health behavior and oral health status among Japanese workers. We quasi-randomly separated participants into the intervention group or the control group at baseline. The intervention group received intensive oral health instruction at baseline and a self-assessment every three months. Both groups received oral examinations and answered the self-questionnaire at baseline and at one-year follow-up. At follow-up, the prevalence of subjects who use fluoride toothpastes and interdental brushes/dental floss were significantly higher in the intervention group than in the control group. Three variables (tooth brushing in workplace, using fluoride toothpaste, and experience of receiving tooth brushing instruction in a dental clinic) showed significant improvement only in the intervention group. On the other hand, work performance and oral status did not significantly change in either group. Our intensive oral health-related behavioral modification intervention improved oral health behavior, but neither work performance nor oral status, among Japanese workers.

**Keywords:** work performance; oral health; intervention study; behavioral modification

### **1. Introduction**

Health impairment influences work performance due to pain, absence for treatment and physical disability [1–4]. The World Health Organization states that protecting workers' health is important to household income, productivity, and economic development, and work-related health problems result in an economic loss of 4–6% of gross domestic product (GDP) for most countries [5].

Several chronic diseases, including oral diseases, were reported to cause economic loss due to impaired work performance [6]. In Japan, 34.8% of workers had problems with work due to oral diseases and impaired work performance [7]. Another study reported that oral diseases indirectly impose an economic burden, costing US\$144 billion in terms of productivity losses due to absenteeism from work [8]. Thus, prevention and control of oral diseases is important for workers to avoid impaired work performance and subsequent economic loss.

Improving individual oral health behavior is effective for preventing oral diseases. Dentists or dental hygienists perform behavioral modification for improvement of patient oral health behavior [9–11]. Adopting methods for behavioral modification, such as "prompt self-monitoring of behavior", "prompt intention formation", "prompt specific goal setting", "provide feedback on performance", and "prompt review of behavioral goals", are effective [12,13]. However, there have been few studies investigating the effects of intervention for behavioral modification on work performance.

We hypothesize that oral health-related behavioral modification intervention will improve work performance by improving oral health behavior and oral health status. This study aims to investigate whether oral health-related behavioral modification intervention influences work performance or improves oral health behavior and oral health status among Japanese workers.

#### **2. Materials and Methods**

#### *2.1. Study Population*

We estimated the sample size using G\*Power and calculated minimum sample sizes for a chi-squared test. We set the effect size at 0.3, alpha at 0.05, and power (1 − β) at 0.80 [14]. The minimum sample size was 108 (chi-squared test). Assuming an attrition rate of 30% [15,16], the planned sample size was therefore a minimum of 308 participants (154 in each group).

Among central or branch offices in Okayama in Japan, we recruited companies that have never received oral examination in work places and agreed to participate in the study. A total of 14 companies in Okayama, Hiroshima, Osaka, and Kyoto cities in Japan agreed to participate in this study. Inclusion criteria for participant recruitment were to complete oral examinations and questionnaires, while exclusion criteria were participants who did not agree to participate. We enrolled 611 workers from April to December 2015 and performed re-examination from April to December 2016.

This study was an assessor-blinded, quasi-randomized trial (alternate allocation). All participants first received an oral examination and answered self-administered questionnaires, and were then divided into two groups in the order in which they came at baseline (2015). After alternate allocation (ratio; 1:1), participants were assigned to the intervention group or the control group. After oral examination, the intervention group received instructions for oral health-related behavioral modification. They were involved in further intervention by the mailing method, which was performed every three months. The control group received only oral examinations. After one year (follow-up) (2016), the two groups received re-examination and answered self-questionnaires.

All study protocols were approved by the Ethics Committees of Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences and Okayama University Hospital (no. 1507-001). Written informed consent was obtained from all targeted participants. Moreover, this study was registered at the University Hospital Medical Information Network (no. 000023011) before commencing.

#### *2.2. Oral Examination*

At baseline and follow-up, six dentists (M.M., T.I., H.M., A.T.-T., A.Y., D.F.) who did not know the allocation performed oral examinations (single blind). The dentists assessed oral health status based on community periodontal index (CPI) [17], debris index-simplified (DI-S) [18] and bleeding on probing (BOP) using a CPI probe (YDM, Tokyo, Japan). CPI, DI-S, and BOP were measured for 10 representative teeth (maxilla: right first and second molar, right central incisor, left first and second molar; mandible: right first and second molar, left central incisor, left first and second molar). CPI scores were binarized; 0–2 vs. 3, 4. DI-S was evaluated in 4 grades (0–3). BOP was expressed as

percentage (%BOP). In addition, the number of present teeth, decayed teeth, and filling teeth were recorded [17]. For assessment, all dentists received training and calibration. Data of CPI score (≤2/>2) were analyzed using a non-parametric kappa test. The kappa coefficients for intra- and inter-examiner reliability were 1.0 and 0.83, respectively.
