Caries Risk Assessment by Dental Students and Dentists in the Netherlands: A Survey Study to Assess Knowledge and Implementation

Dental caries is the most prevalent oral disease worldwide and affects individuals of all ages in both developed and developing countries [1‒6]. Its multifactorial nature requires the identification of risk factors associated with the onset and progression of caries lesions (e.g., sociodemographic and behavioral factors) to provide individualized and tailored healthcare [6, 7]. Caries risk can be described as “the probability of caries disease development in the near future” and varies during a patient’s lifetime [1].

The consensus development conference statement of the National Institutes of Health acknowledged in 2001 that the invasive nature of treatments in caries management has shifted toward a more conservative and preventive strategy [8]. Nowadays, an increasingly utilized and accepted concept is minimal intervention (MI) dentistry [9]. This concept emphasizes conservative values and aims to maintain functional and intact teeth throughout a person’s life, preventing caries lesions [10]. To prevent caries progression and follow a conservative approach, it is believed that it is essential to detect early stages of caries lesions and individually predict future lesion onset [3]. A personalized prevention and care plan must be based on individual needs and individual risk factors potentially involved in future lesion development for which caries risk assessment (CRA) can be applied. This individualized approach allows for preventive or therapeutic measures to be tailored to the specific needs of each patient and could avoid the unnecessary use of typically limited resources and time for patients who do not require extensive treatment, while paying more attention to those who do [11].

Based on the beneficial results of the Nexø model [12] and the subsequent experiences in the Netherlands [13], the Dutch Oral Health Association (Ivory Cross) introduced an individually targeted caries prevention program named “Gewoon Gaaf” (translated to “just cool and cavity free”). The primary goal of this program was to make children and their parents/caregivers aware of their role in preventing dental caries and maintaining intact teeth in patients aged 0–18 years [14]. The Dutch National Health Care Institute recently reported that there is a deterioration of the oral health situation of young people, especially teenagers, compared to 2011 [15]. However, in contrast to teenagers, the oral health of 5-year-old children has improved. This tendency can be explained by the increased attention paid to the oral health of young children through caries prevention programs such as “Gewoon Gaaf” [16].

CRA is an essential component of modern preventive and MI dentistry, yet its integration into clinical practice varies widely. The Netherlands offers a unique perspective for examining CRA practices as its dental education and public health approaches prioritize preventive care. This study’s findings may reflect global challenges and opportunities in CRA implementation, providing insights relevant to educators and practitioners worldwide. A critical issue is the gap between CRA as an educational objective and its practical application in the daily dental practice. Dental schools and their teachers face the challenge of making CRA tools both relevant and feasible for daily practice rather than solely teaching goals. By exploring CRA use among Dutch dental students and practitioners, the current study aimed to inform strategies that bridge educational and clinical applications of CRA, ultimately enhancing preventive care practices internationally. The use of CRA in everyday clinical practice is a lever for better oral health. Several studies analyzed the use of CRA in general dental practice [11, 17‒19] and in dental faculties [20, 21], but none were undertaken in the Netherlands. CRA and the detection of incipient caries should start at dental schools by educating dental students. There are three dental schools in the Netherlands (Groningen, Nijmegen, and Amsterdam), and education on CRA is implemented in the curricula as described in domain II of the core curriculum in cariology [22]. Students are taught that applying CRA in some form is an integral part of the periodic oral examination. However, it is not known to what extent the knowledge imparted in the curriculum also contributes to the attainment of the competences after graduation. If dental students widely used CRA during their education, it is expected that when in practice, they would keep using tools to assess caries risk, with the benefits associated with these strategies. It is, therefore, important to explore their knowledge of Dutch prevention-oriented methods and their use of CRA during regular checkups. The aim of this study was to investigate the knowledge and application of CRA among Dutch fifth-year dental students (D5DSs) and Dutch dental practitioners (DDPs) to assess the extent to which knowledge from the core curriculum in cariology is implemented in the clinical part of the education and subsequently applied in daily practice. This research may provide valuable insights into the extent to which parts of the core curriculum in cariology have been adopted by dental schools and whether this has had an impact on patient care by DDPs.

A survey was conducted using a questionnaire developed for a French study [19] in both French and English. The English version was translated into Dutch and was later back translated to English for verification purposes by a Dutch dentist with a Cambridge First Certificate in English and International Baccalaureate English A2. To make this survey explicitly applicable for the Netherlands, questions were added or modified for the Dutch situation. In brief, the main adjustments of the questionnaire for the Dutch context were a question about task delegation (in the Netherlands, dental hygienists and prevention assistants are an integrated part of the dental team), integration of the caries prevention advices of the Ivory Cross (the Dutch Oral Health Association) in the answers, and its “Gewoon Gaaf” program (the Dutch implementation of the Nexø project).

The questionnaire started with questions regarding demographic data (e.g., birth year, sex, current or former university). The following sections contained questions regarding CRA and various preventive strategies. Subsequently, knowledge about MI in cariology and familiarity with caries prevention-oriented methods in the Netherlands were assessed. Participants were asked to rate the importance of factors in assessing caries risk using a 5-point Likert scale and a dominance hierarchy. Finally, educational related questions, such as if they read articles on MI in cariology and if they would like to receive more education on caries risk recording, were asked. For the final questionnaires, see online supplementary Data S1 and S2 (for all online suppl. material, see https://doi.org/10.1159/000545155).

Considering the study aim of exploring knowledge and application of CRA by Dutch DSs and DDPs, questionnaire validation is not relevant, similar to other practice studies dealing with CRA [11, 17, 19]. However, a pilot study was conducted (n = 10) to test adequacy, comprehensibility and to assess validity to a certain extent. The respondents mainly indicated that the questionnaire was long and needed too much time to complete, after which the questionnaire was adjusted. The study protocol had been approved by the internal review board of ACTA (ETC protocol No. 2018011; the Dutch Medical Research Involving Human Subjects Act did not apply to this study).

In April 2018, D5DSs from all three dental faculties in the Netherlands were invited (Amsterdam [n = 119], Nijmegen [n = 50], Groningen [n = 44]). A total of 213 D5DSs were enrolled at the time and were approached to participate (87.7% of the total number of D5DSs in the Netherlands) [23]. The dental curriculum in the Netherlands is 6 years in total (academic year runs from September to June) with the 6th year consisting mainly of clinical internships, writing a thesis and education in practice management. In year 5, the theoretical foundation in dentistry is well established and there has also been extensive clinical teaching. A random sample of 1,500 members of the Royal Dutch Dental Association (KNMT) was invited to take part in the study (15.8% of the total active KNMT members [24]).

The questionnaire was initially conducted online through SurveyMonkey Inc. (San Mateo, CA, USA, nl.surveymonkey.com) in November 2016 and later sent per post in April and May 2017. After informing potential participants about the aim of the questionnaire, they were asked to give written informed consent for their participation in the study. If they did not provide their consent, they were excluded from the study. Participation was anonymous and no personal data were collected.

The data from the received questionnaires from D5DSs and DDPs were combined into one SPSS file and all analyses were performed using SPSS Statistics version 26.0 (IBM corp., Armonk, NY, USA). The percentages in the results were only based on the completed data as questionnaires with missing data were not included. Chi-square tests were used for categorical variables. The non-categorical variable “age” was not normally distributed in the population (Shapiro-Wilk test, p < 0.05) and nonparametric tests were used. The representativeness of the DDP respondents compared to the general population of practicing dentists in the Netherlands [24] was analyzed with a one-sample t test and chi-square test. For all statistical analyses, the significance level was set at p < 0.05.

In total, 118 D5DSs (55%) and 374 DDPs (25%) completed the survey. D5DSs had a mean age of 25.2 years (standard deviation = 2.4). Of the 374 DDPs, 39% were younger than 39 years, 27% between 40 and 54, and 34% between 55 and 67 years (Table 1). DDP respondents statistically differed in age and gender compared with the general population of practicing dentists in the Netherlands [24]. DDP respondents statistically differed in age (mean = 45.52; standard deviation = 12.38) compared with the general population of practicing dentists in the Netherlands [24] (t[374] = −2.16; p = 0.03). Most participants were female in both groups (D5DSs: 64%; DDPs: 52%), which is different to the general population of practicing dentists in the Netherlands (44% females; Table 1). Regarding the DDPs, significantly more female respondents participated compared to the general population of practicing dentists in the Netherlands (χ² [1] = 10.68, p = 0.001). Most D5DSs and DDPs graduated from ACTA (the largest Dutch dental school). For the full dataset, see online supplementary Data S3.

All D5DSs (100%) reported using CRA in routine in contrast to DDPs (79%; Table 2). DDPs (69%) and D5DSs (77%) preferred to determine caries risk without the use of a special tool (like a preset form or questionnaire, such as the cariogram). Ten percent of the DDPs and 23% of the D5DS used a CRA form/tool. Most of the DDPs who are using CRA assessed caries risk in both primary/mixed and permanent dentitions (88%). Two-thirds of the D5DSs (68%) did so, although there are differences between the three dental schools (χ² = 18.671, p < 0.001). Female DDPs reported to use CRA more often than males (χ² = 6.96, p = 0.008). DDPs who did use CRA had significantly more recently graduated compared to those who did not (Mann-Whitney test, U = 6208, p = 0.002).

Most D5DSs and DDPs based an individual treatment plan, the frequency of dental visits, and the implementation of preventive programs on CRA. No significant difference was shown between the dental schools (Kruskal-Wallis test, H = 0.188, p = 0.910).

Limited available time during dental visits was the main reason for not using CRA, followed by inadequate education and difficulties with billing or reimbursement. Furthermore, 66% of the DDPs and 43% of the D5DSs were interested in more education regarding CRA. DDPs preferred a course or seminar (83%) whereas D5DSs preferred a Dutch scientific journal (72%).

There was a large variability between D5DSs and DDPs regarding familiarity with prevention-oriented methods (Table 3). Although the majority of the D5DSs were familiar with prevention-oriented methods such as the Dutch Caries Prevention Advice [25], prevention program “Gewoon Gaaf,” and the conversation technique motivational interviewing, only two-thirds of the DDPs reported to be familiar with these methods. The familiarity of DDPs regarding Dutch prevention-oriented methods was lower than D5DSs (χ² = 27.65, p < 0.001). Dentists used most frequently the Dutch guidelines (54%), followed by motivational interviewing (36%) and “Gewoon Gaaf” (30%). Moreover, 80% of the D5DSs and 59% the DDPs recommended their patients use fluoride according to the Dutch Caries Prevention Advice.

Approximately 88% of the respondents read scientific articles about MI in cariology (Table 4). Both D5DSs and DDPs agree that the most appropriate concepts of MI in cariology are based on prevention, minimally invasive dentistry, and understanding risk factors.

The level of knowledge on CRA was not significantly correlated with the utilization of the Dutch prevention programs “Gewoon Gaaf” and the Ivory Cross Dutch Caries Prevention Advice (both p > 0.05). When correlating knowledge about CRA with the implementation of a treatment plan, it appears that 77% of the respondents claim both to have knowledge about CRA and regularly implement a treatment plan (p < 0.001).

The importance of various factors concerning CRA was assessed in two different ways: a 5-point Likert scale and dominance hierarchy. Despite the different approaches, the results appeared to be consistent and in agreement with each other. DDPs considered oral hygiene (64%), diet (45%) and parents’ help (45%) as the most important factors when assessing caries risk in patients aged under 18 years (Table 5). Oral hygiene and diet were factors that also applied to the group of patients aged over 18, though the presence of recent caries lesions in the previous 2 years (43%) was considered as the third most important factor. Students also considered oral hygiene and diet as the most important factors for assessing caries risk in patients under 18 years old; but, in contrast to DDPs, D5DSs considered the presence of active caries lesions (48%) as the third most important factor. In patients aged over 18 years, students considered oral hygiene (74%), active caries lesions (53%), and diet (45%) as the three most important factors in CRA. Other factors that both DDPs and D5DSs considered important for effective CRA in both age categories were the presence of caries lesions, whether recent or not, and the use of fluoride-containing toothpaste.

Reimbursement was by far the least prominent factor in both age-groups according to the D5DSs. Furthermore, gingival recessions/exposed roots, orthodontics/prosthetics, and socioeconomic status were three of the least important factors according to DDPs in both patient groups.

This study is the first in the Netherlands exploring knowledge and application regarding CRA in a group of almost graduated dental students and dental practitioners. Our overall finding was that D5DSs are more familiar with CRA than DDPs and tend to use it more frequently during clinical practice. Both D5DSs and DDPs agree that the most suitable principles of MI in cariology revolve around prevention, minimal invasive dentistry, and comprehension of risk factors. The results show that the use of CRA and familiarity with MI was fair and similar among D5DSs from all three Dutch dental schools, although some D5DSs would ask for further education on the topic.

All D5DSs who participated in this study reported utilization of CRA during patient treatment. Although the use of a specific CRA form is not mandatory, it is widely understood by students as the desired practice. This may suggest that socially desirable responses were given, potentially explaining the exceptionally high percentage. However, based on previous research conducted at one of the dental schools, we know that the caries risk of patients has been consistently recorded in the online patient registration system for many patients (data not published). Therefore, we believe these figures to be reliable. The reported numbers are higher in comparison with a similar study among French 5DSs (81.1% [21]). Calderon et al. [20] reported that D5DSs are acknowledging their insufficient knowledge regarding CRA and preventive treatment strategies and that they are not fully confident using CRA, especially in patients aged below 12 years.

The response rate of the DDPs in this study (25%) is in the range of those obtained in similar surveys in France and Croatia (respectively, 35% and 17%) [18, 19]. However, these rates are not in line with the higher percentages of previous studies from dental practice-based research networks in Japan (67%) and USA/Scandinavia (58%) [11, 17]. A possible explanation for these lower response rates is the voluntarily participation of the France, Croatian, and Dutch respondents, whereas the Japanese and US/Scandinavian studies included respondents from the dental practice-based research networks, a social network of dental professionals dedicated to promoting dental practice-based research. Since the current study was conducted with individuals who voluntarily participated in the survey, it is plausible that the utilization of CRA is overrepresented in our study population, potentially influencing the outcomes of our research.

It appears that 79% of the DDPs declared using CRA in everyday practice. This is a higher percentage compared to similar studies in the USA (69%), France (62%), Croatia (47%), Brazil (36%), China (31–35%), Japan (26%), and India (25%) [11, 17‒19, 26‒29]. The relatively high percentage of CRA use in the Netherlands could potentially be explained by a combination of factors: the effective integration of the core curriculum in cariology [22] within dental schools, the substantial emphasis on (oral) disease prevention in the Netherlands, and the well-implemented practice of performing regular dental checkups (irrespective of possible symptoms by the patient). Regulations dictate that this checkup includes a comprehensive risk assessment of their current oral health status during these visits.

Female DDPs reported using CRA at a daily basis more frequently than males; these results might be biased by the higher percentage of female respondents in the present survey. A study of Riley et al. [30] has reported that female dentists have a less invasive approach and generally have a more preventive treatment philosophy than males. This can also explain the higher utilization of CRA by female dentists compared to male dentists in the current study. This could have influenced the outcomes of the current survey as it is conceivable that volunteers might harbor a more favorable sentiment toward CRA.

To date, CRA is not fully validated [4, 31, 32]. Due to the multifactorial nature of caries, CRA can be challenging leading to the development of multiple tools [33]. However, these tools are lacking validation, accuracy, adequacy, and standardization, which may result in false prediction of the onset of caries lesions [34]. Consequently, enhanced methods for CRA are required [35]. The implementation of a tool for CRA would be helpful in minimizing subjective interpretations. However, the concept of CRA must be validated first ensuring that this future tool is well-founded before it is implemented. Interestingly, most D5DSs and DDPs performed CRA in their daily practice without using a special tool and these results are in accordance with previous studies [11, 17, 18, 26‒28].

Although the data have been collected 5 years ago, they remain highly applicable due to the stable and consistent approach toward prevention in oral healthcare practices in the Netherlands. Over the past few decades, there were no major changes in relevant protocols, technologies, or interventions. For instance, the current Ivory Cross Dutch Caries Prevention Advice dates from 2011, and the “Gewoon Gaaf” project has been implemented in 2014. Moreover, the current core curriculum in cariology dates back to 2010 and is still followed in all three dental schools [36]. Therefore, the data can still be considered valid and reflective of current practices.

The shift toward a more conservative and preventive approach in cariology has gained popularity among dental professionals over the past decades. Dental universities in Europe have now incorporated the domains of the core curriculum for cariology into their education, aiming to equip graduating dental students with the skills for optimal caries diagnosis and management [37]. Results of this study indicate that prevention-oriented methods in the Netherlands are familiar to most D5DSs, when this is not the case for practicing dentists. Indeed, about 30% of the dentists were not familiar with the Dutch Caries Prevention Advice from the Ivory Cross [25], Dutch initiatives like “Gewoon Gaaf,” and the motivational interviewing technique, and these methods were not frequently used in daily practice. Of the DDPs familiar with the Dutch Caries Prevention Guideline, 35% reported to apply only the fluoride toothpaste recommendation in the daily practice, without diet and/or oral hygiene advice. This discrepancy is interestingly inconsistent with DDPs’ rating of oral hygiene and diet as the two most important factors for CRA. A possible explanation may be the assumption that patients know their role in these factors, though this hypothesis needs to be tested.

In the present study, oral hygiene and diet are both assessed as the most important factors for CRA by most D5DSs and DDPs. These results are consistent with the Brazilian, Croatian, Chinese, and French studies [18, 19, 26, 27]. Kakudate et al. [11] also reported oral hygiene as the most important factor in CRA. Another factor identified as an important predictor for future caries is the presence of (recent) caries lesions and the use of fluoride-containing toothpaste [38]. These have been recognized risk factors for caries prediction and are therefore included in the current CRA methodology. The current study also indicates that these two factors emerge as important by participants, but they are subordinate to the primary causative factors related to caries, which are oral hygiene and diet.

Approximately a quarter of the DDs and half of the D5DSs found their own subjective analysis less important. Additionally, subjective analysis was considered one of the least important factors for CRA in patients aged over 18 years. Although a dentist’s subjective analysis appears to increase sensitivity CRA [39] and has predictive value for CRA [40], it is likely that respondents gave socially desirable answers.

The study’s results highlight a crucial disconnect between CRA as an academic exercise and its actual implementation in clinical practice. This disconnect underscores the need for dental education programs to equip students with practical CRA tools that are not only theoretically sound but also feasible in the daily practice. Teachers should consider the evolving needs of practicing dentists, including efficient, validated CRA tools that support preventive care without imposing significant time burdens. This study’s findings, though specific to the Netherlands, resonate with global trends as CRA continues to be an underutilized tool despite its recognized value in preventive dentistry. Addressing these challenges could lead to a more universal adoption of CRA in daily practice, benefiting both practitioners and patients by facilitating targeted, individualized care plans.

For practitioners, updating their knowledge regarding the newest concepts in cariology is important due to possible unfamiliarity with them and Dutch caries management programs. Given the importance of CRA in caries management, dentists in the Netherlands could benefit from additional education to increase their understanding of CRA and prevention-oriented methods, enabling its effective implementation in daily practice. Dental schools could put more emphasis on research on the scientific base of CRA and systematic documentation in clinical practice. A sound scientific basis of CRA helps with further implementation in both curriculum and daily practice. The systematic and transparent documentation of risk factors enables this research and can help in the future to develop reliable CRA tools that can help this process.

The authors would like to thank the Royal Dutch Dental Association (KNMT) for providing the random sample of dentists and the three dental student associations for their cooperation with data collection at the universities.

The study protocol had been reviewed and approved by the internal review board of ACTA (ETC protocol No. 2018011; the Dutch Medical Research Involving Human Subjects Act did not apply to this study). Written informed consent was obtained from all participants in this study.

The authors have no conflicts of interest to declare. Prof. Dr. Rodrigo A. Giacaman was a member of the journal’s Editorial Board at the time of submission.

The study was not supported by any sponsor or funder.

C.M.C.V. and H.S.: conception and design, data acquisition and analyses, drafting the work, and final approval. R.A.G.: analyses, drafting the work, and final approval. I.F.P.: data acquisition and analyses, reviewing the work, and final approval. S.D.: conception and design, reviewing the work, and final approval.

Data and the two questionnaires (dentists and students) are available as online supplementary material. Further inquiries can be directed to the corresponding author.