**1. Introduction**

Access to regular dental visits is important to avoiding oral diseases [1,2]. Nevertheless, it should be noted that avoiding or postponing dental visits is frequent in Germany [3,4]. For example, this behavior could lead to periodontitis and caries lesions which could ultimately result in tooth loos [5]. Furthermore, postponed dental visits can additionally affect quality of life [6]. Consequently, poor oral health can decrease functional health [7].

**Citation:** Hajek, A.; De Bock, F.; Huebl, L.; Kretzler, B.; König, H.-H. Postponed Dental Visits during the COVID-19 Pandemic and their Correlates. Evidence from the Nationally Representative COVID-19 Snapshot Monitoring in Germany (COSMO). *Healthcare* **2021**, *9*, 50. https://doi.org/10.3390/ healthcare9010050

Received: 4 December 2020 Accepted: 28 December 2020 Published: 5 January 2021

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**Copyright:** © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

Previous studies have focused on determinants of nonattendance and dental treatment avoidance [4,8], rather than postponement of dental visits as the outcome measure. Furthermore, studies determined postponement for financial reasons [3]. For example, it has been shown that dental anxiety is associated with avoidance behavior [8]. Moreover, it has been demonstrated that avoidance of dental treatment is associated with younger age, lower social status, unemployment, and decreased health (in terms of increased physical illnesses and increased depressive symptoms) [4].

Existing studies focused on nonattendance, avoidance, or postponement of dental visits prior to the COVID-19 pandemic. Thus far, one economic analysis using a modelling approach exists focusing on the impact of COVID-19 on dental practices [9]. A telephonebased survey conducted from 24 March to 2 April 2020 (146 German dentists) [9] showed that mitigation/suppression decreased use of dental services, particularly prevention (−80% in mean), periodontics (−76%), and prosthetics (−70%). According to Schwendicke et al., COVID-19 and associated policies had an economic impact on dental practices in Germany [9]. Comparably, a study conducted in China (Beijing) from 1 February to 10 February 2020 showed that the COVID-19 pandemic significantly decreased the use of emergency dental services (e.g., 38% fewer patients had emergency dental visits at the beginning of the COVID-19 pandemic compared to one month prior to the pandemic) [10]. During the same period, the proportion of oral and dental infections significantly increased [10].

However, up to now, nationally representative studies focusing on postponed dental visits (in general, rather than directly cost-related) and its correlates are lacking. We aimed to fill this gap in knowledge.

To put our findings into context, in Germany, corona measures such as school closings or closing of daycare centers were implemented on 16 March 2020. A week later (22 March 2020), public restrictions and travel bans followed. These measures were prolonged in subsequent weeks. Restrictions were loosened on the 20 April 2020. In the beginning of May, schools gradually reopened. In May, additional restrictions were loosened (e.g., playgrounds reopened and contact bans loosened). Further restrictions eased in June. Nevertheless, a spike in COVID-19 cases could lead to a reimplementation of regulations.

It is necessary to describe key characteristics of the German healthcare system. Health insurance is compulsory in Germany. Approximately 9 out of 10 individuals are members of the social statutory health insurance (SHI), solely 1 out of 10 individuals has private health insurance (PHI). Predominantly, civil servants, employed individuals exceeding a defined income threshold, and self-employed individuals can opt for PHI. Both categories of health insurance (PHI and SHI) cover most expenses of outpatient treatment (even for dental care services) in Germany. Access to health care is commonly guaranteed for all insured individuals. However, additional dental services (e.g., gold or ceramic inlays) which have an unproven medical benefit are usually not covered in SHI. It should be emphasized that waiting periods are relatively short in Germany [11,12]. Passon et al. give further insight into the German health care system [13]. With regard to the COVID-19 pandemic, it should be noted that routine dentistry was allowed to continue in Germany. It was therefore not restricted to emergency appointments.

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

### *2.1. Sample*

Cross-sectional data were collected from wave 17 of the COVID-19 Snapshot Monitoring (COSMO) [14]. Solely in wave 17 individuals were asked about postponed dental visits.

The COSMO study started in early March 2020 (3rd/4th March) with weekly followup waves until 26 May. Afterwards, the survey continued in a 14-day interval. Wave 17 was conducted from 21st to 22nd of July 2020. In wave 17, *n* = 1001 individuals aged 18 to 74 years participated. Individuals younger than 18 years and individuals older than 74 years were excluded in this wave.

A market research company (Respondi) conducted the recruitment of participants from an online panel matching distribution of age, gender (crossed-quota: age x gender), and federal state (uncrossed) within the German population [15]. A large sample size was chosen to also detect small effects in the COSMO study [16].

Informed consent was obtained from all individual participants included in the study. Ethical approval for COSMO was obtained by University of Erfurt's IRB (#202000302). All procedures performed in the COSMO studies involving human participants were in accordance with the ethical standards of the University of Erfurt institutional research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
