Background: Oral health (OH) is poor among young adults in Russia, but there is little information on OH-related quality of life (OHRQoL) in this population. We investigated how socio-demographic factors, self-reported OH characteristics, oral health behaviour, and clinically-assessed OH are related to OHRQoL in medical and dental students in North-West Russia. Methods: This cross-sectional study included 391 medical and 275 dental Russian undergraduate students aged 18–25 years. Information on socio-demographic, self-reported OH characteristics, and oral health behaviour was obtained from a structured, self-administered questionnaire. A clinical examination was performed to assess dental caries experience based on the decayed (D) missing (M) filled (F) teeth (T) index; Simplified Oral Hygiene Index; and Gingival Index. OHRQoL was measured by the OH Impact Profile (OHIP-14). Results: 53.6% of students reported low OHRQoL during the last 12 months. Female sex (odds ratio [OR] = 1.48, 95% confidence interval [CI]: 1.00–2.19), rural place of childhood residence (OR = 1.56, 95% CI: 1.06–2.28), poor self-assessed dental aesthetic (OR = 1.75, 95% CI: 1.16–2.64), dissatisfaction with mouth and teeth (OR = 2.51, 95% CI: 1.68–3.77), and DMFT index (OR = 1.05, 95% CI: 1.01–1.09), were all significantly, independently associated with low OHRQoL. Conclusion: Socio-demographic factors (rural place of childhood residence, female sex), poor self-reported OH characteristics, and high DMFT index were associated with low OHRQoL.

Little information exists about the experience of and risk factors for dental caries in young adults in Russia. We investigated dental caries experience and determinants in medical and dental students in North-West Russia. This cross-sectional study included 442 medical and 309 dental undergraduate students of Russian nationality aged 18–25 years from the Northern State Medical University, Arkhangelsk, Russia. Information on socio-demographic factors and oral health behaviour (regularity of dental visits, frequency of tooth-brushing, using toothpaste with fluoride, and skipping tooth-brushing) was obtained from a structured, self-administered questionnaire. Dental caries experience was based on the decayed (D) missing (M) filled (F) teeth (T) index and the Significant Caries (SiC) index, which were assessed through dental examination. Students with a DMFT index ≥9 were placed in the SiC group. Negative binomial hurdle and multivariable binary logistic regressions were used for statistical analyses. The prevalence of dental caries (DMFT >0) was 96.0%, overall mean DMFT index was 7.58 (DT: 0.61, MT: 0.12, and FT: 6.84), and the corresponding SiC index was 12.50. Age 21–25 years (incidence rate ratio [IRR] = 1.09, 95% confidence interval [CI]: 1.01–1.18), being a female (IRR = 1.10, 95% CI: 1.01–1.20), high subjective socioeconomic status (SES) [IRR = 1.11, 95% CI: 1.02–1.21], and skipping tooth-brushing (IRR = 1.09, 95% CI: 1.00–1.19) were associated with a higher DMFT index. DMFT index also increased among students who reported regular dental visits (IRR = 1.22, 95% CI: 1.10–1.36), but their odds of being in the dental caries-free group decreased (odds ratio [OR] = 0.38, 95% CI: 0.18–0.82). Significant predictors of being categorised to the SiC group were older age (OR = 1.41, 95% CI: 1.03–1.92), high subjective SES (OR = 1.57, 95% CI: 1.13–2.19), and regular dental visits (OR = 2.34, 95% CI: 1.56–3.51). A high prevalence of dental caries and high DMFT index, with a dominance of FT, were observed in our Russian medical and dental students. Age, sex, subjective SES, regular dental visits, and skipping tooth-brushing were determinants of dental caries experience.

The objective was to assess the prevalence of and factors associated with dental anxiety (DA) in medical and dental students in North-West Russia. This cross-sectional study included 422 medical and 285 dental undergraduate Russian students aged 18–25 years from the Northern State Medical University in Arkhangelsk. Corah’s Dental Anxiety Scale (DAS) was applied to measure DA. Information on socio-demographic and socioeconomic factors, oral health behaviour and general and oral health was obtained from a structured, self-administered questionnaire. A clinical examination was performed to assess caries experience, Simplified Oral Hygiene Index, and Gingival Index. DAS score ≥13 was found in 13.7% and 2.2% of medical and dental students, respectively. Female sex (incidence rate ratio [IRR] = 1.11, p = 0.013), lower education of mother (IRR = 1.13, p = 0.001), and poor self-assessed oral health (IRR = 1.15, p < 0.001) were associated with DA in medical students. Corresponding factors in dental students were female sex (IRR = 1.16, p = 0.001), irregular dental visits (IRR = 1.19, p = 0.001), infrequent tooth-brushing (IRR = 1.17, p = 0.007), pain in mouth (IRR = 1.09, p = 0.031) and number of missing teeth (IRR = 1.13, p = 0.007). The prevalence of high DA was lower in dental students than in medical students. DA was associated with sex, mother’s education, poor oral health behaviour and self-assessed and clinically assessed oral health.

We aimed to investigate changes in management preferences for deep carious lesions and pulps exposed during carious tissue removal that occurred during the last 10 years and identify associated dentists’ background factors. The data were collected among dentists registered with the Lithuanian Dental Chamber at two time points using a similar questionnaire. In 2011, 400 randomly selected dentists received a questionnaire by mail, and 153 (38.3%) responded. In 2021, an electronic invitation to an online questionnaire was sent to all members of the Lithuanian Dental Chamber, and 213 (8.9%) dentists responded. The questionnaire included the definitions of management options, a radiograph, and a clinical picture of a deep carious lesion reaching to the inner fourth of dentine in a mature permanent tooth, asked management preferences in four different scenarios, as well as participants’ background characteristics, reasons for management, and procedural preferences. Data were analyzed using bivariate and multivariable analyses. Compared to 2011, participants in 2021 had 60% lower odds of preferring nonselective versus selective caries removal (OR 0.4, 95% CI 0.2–0.7) and endodontic treatment versus nonselective and selective caries removal (OR 0.4, 95% CI 0.2–0.6) in the scenario of asymptomatic and symptomatic (indicating reversible pulpitis at most) deep lesions, respectively. For exposed pulp, participants in 2021 had lower odds than in 2011 of preferring endodontic treatment versus vital pulp therapy (direct pulp capping and pulpotomies) for both scenarios without symptoms (OR 0.4, 95% CI 0.2–0.7) and with symptoms (OR 0.2, 95% CI 0.1–0.4). A higher proportion of respondents in 2021 reported using rubber dam (44% vs. 17% in 2011, p < 0.001) and hydraulic calcium silicate cements as a capping material (68% vs. 40% in 2011, p < 0.001). The management preferences were associated with the university of graduation and the number of years in dental practice, indicating “recommended in textbooks” and “recommended in scientific publications” as reasons for management preferences. To conclude, a change toward less invasive management options was observed. To a certain extent, dentists have implemented evidence-based recommendations in dental practice. To ensure further adoption of scientific evidence, dentists should be encouraged to update themselves on the newest evidence-based practices.

The cross-sectional study design is widely prevalent in Russian medical literature. However, a significant number of these studies neglect to calculate the sample size during the planning phase, and the analysis often relies solely on basic bivariate statistics. This compromises the validity of the findings and increases the risk of drawing inaccurate conclusions. The scientific rigor of a study depends on a quality of planning, a clear problem statement, and precise formulation of statistical hypotheses, which are then tested using the most appropriate analytical methods. At the core of this process lies the determination of the appropriate sample size. The primary objective of this article is to provide a comprehensive, step-by-step guide for the sample size calculation process. By adhering to our guidelines, researchers can ensure that their cross-sectional studies possess sufficient statistical power to generate meaningful results. We acknowledge the significance of tailoring sample size calculations to the specific objectives and data characteristics of each study. Therefore, our approach is designed to be flexible and adaptable, accommodating the unique requirements of diverse research endeavors. There are several software options available for sample size calculation; however, we use the G*Power software for all the examples presented in this paper. Our guide is designed to provide practical understanding of the topic, with each step being accompanied by illustrative examples and detailed screenshots. This approach ensures that the material is not only understandable but also applicable in real-world scenarios. Furthermore, we take the extra step of interpreting every dialog box and screenshot, aiming to create a comfortable user experience with the software. We hope that this paper will serve as a valuable guide in the planning stage of a study, helping researchers to address a wider range of issues and reliably estimate the associations between selected exposures and the outcomes of interest with sufficient statistical power.

The aim is to assess oral health-related quality of life (OHRQoL) and factors associated with OHRQoL among the students of the medical university. Methods. The cross-sectional study included 308 Russian speaking third year students aged 19-25 years from the Faculty of General Medicine, Paediatrics, Preventive Medicine and Dentistry of the Northern State Medical University (NSMU), Arkhangelsk, Russian Arctic. The Oral Health (OH) Impact Profile (OHIP-14) was used to measure OHRQoL. Information on socio-demographic factors, self-esteem of tooth and gingiva health, OH behaviour, and diet was obtained from the OH Questionnaire for adults (World Health Organization, 2013). Pearson's chi-square test and multivariable Poisson regression with robust estimate of dispersion were used for statistical analysis. Results: 33,8 % and 18,5 % of students had poor dentition and gingiva, respectively. 39,0 % of students consumed sweet pies/buns more than once a week; 39.0 % of students reported on low OHRQoL. The highest mean scores OHIP-14 were found for the dimensions "physical pain" and "psychological discomfort": 1.59 (95 % confidence interval (CI): 1.43-1.75) and 0.84 (95 % CI: 0.70-0.98), respectively. Female sex (prevalence ratio (PR) = 1.73, 95 % CI: 1.23-2.45), poor self-esteem of teeth health (PR = 2.32, 95 % CI: 1.77-3.04), and sweet pies/buns consumption more than once a week (PR = 1.39, 95 % CI: 1.07-1.80), were all significantly and independently associated with low OHRQoL. Conclusions: Relatively high prevalence of low OHRQoL was observed in the examined students. Female sex, poor self-esteem of teeth health and frequent consumption of sweet pies/buns were associated with low OHRQoL. To enhance OHRQoL in Russian students, the preventive strategies for dental diseases and diet improvement should be implemented.