Prediction of high-risk individuals and the multi-risk approach are common inquiries in caries risk epidemiology. These studies prepared the ground for future studies; specific hypotheses about causal patterns can now be formulated and tested applying advanced statistical methods designed for causal studies, such as structural equation modeling, path analysis and multilevel modeling. Causal studies should employ measurements, analyses and interpretation of findings, which are in accordance to causal aims. Examples of causal empirical studies from medical and oral research are presented.

This study examined whether the authoritative parenting model (APM) is more effective than conventional approaches for changing adolescent oral hygiene behavior. A total of 247 adolescents were recruited using a cluster random-sampling method. Subject groups were randomly allocated into an intervention group (APM-based interventions), a Control Group 1 (conventional dental education and behavior modification) or a Control Group 2 (conventional behavior modification). The results were assessed after 3 and 12 months. Oral hygiene level was assessed as percent dental plaque and the ratio of plaque percent change (RPC). At the 3-month follow-up, there were significant differences among the groups; the APM group had the largest decrease in plaque levels (24.5%), Control Group 1 showed a decrease in plaque levels of 15.4% and Control Group 2 showed an increase in plaque levels of 2.8%. At the 12-month follow-up, an improvement was observed in all groups, but there were no statistically significant differences among the groups. In the short term, the intervention based on the APM was more effective in changing adolescent oral hygiene behavior compared with the conventional approaches. The reasons for long-term positive change after discontinued interventions in control groups need to be explored in future studies.

The present study aimed to evaluate and compare the radiopacity and surface morphology of AH Plus Bioceramic Sealer (AHPB), Bio-C Sealer (BIOC), Biodentine (BD), BioRoot RCS (BR), Grey-MTAFlow (GMF), White-MTAFlow (WMF), TotalFill BC Sealer (TF), and TotalFill BC Sealer HiFlow (TFHF) at different time moments—30 min, 24 h, and 28 days. Ten specimens of each material were prepared according to the ISO-6876:2012 standard and radiographed next to an aluminum step wedge using a digital sensor. The specimens were stored in a gelatinized Hank’s balanced salt solution at 37 °C between assessments. The mean grayscale values of each specimen were converted into equivalent aluminum thickness by a linear regression model. Characterization of the surface morphology was performed by using a scanning electron microscope at ×4.0k and ×10.0k magnifications. The radiographic analysis revealed that all the tested materials exceeded the ISO-specified limit of 3 mm Al, with the highest radiopacity presented by AHPB and the lowest by BD. None of the tested materials demonstrated considerable variances between the 30 min and the 24 h radiopacity level (p < 0.05), and statistically significant long-term radiopacity changes were exhibited by BR, TFHF, and TF (p > 0.05). All the specimens demonstrated a common feature of limited precipitate formation, with numerous unreacted particles still presented on the surface after 24 h, whereas the particle rearrangement and the deposition of precipitates were clearly observed after 28 days.

The better understanding of the clinically important behavioral features of new instrument systems has an important significance for the clinical endodontics. This study aimed to investigate the shaping and centering ability as well as cyclic fatigue resistance of HyFlex CM (CM), HyFlex EDM (EDM) and EdgeFile (EF) thermally treated nickel–titanium (NiTi) endodontic instrument systems. Sixty curved root canals of the mesial roots of mandibular molars were randomly assigned into three groups (n = 20) and shaped using CM, EDM and EF files up to the size 40 and taper 04 of the instruments. µCT scanning of the specimens before and after preparation was performed and the morphometric 2D and 3D parameters were evaluated in the apical, middle and coronal thirds of root canals. In each group, 40.04 instruments (n = 20) were subjected to the cyclic fatigue resistance test in artificial root canals at 37 °C temperature until fractures occurred, and the number of cycles to failure (NCF) was calculated. The fractographic analysis was performed using a scanning electron microscope, evaluating topographic features and surface profiles of the separated instruments. The one-way analysis of variance with post hoc Tuckey’s test was used for statistical analysis of the data; the significance level was set at 5%. All systems prepared the comparable percentage of root canal surface with the similar magnitude of canal transportation in all root thirds (p > 0.05), but demonstrated significantly different resistance to cyclic fatigue (p < 0.05). The most resistant to fracture was EF, followed by EDM and CM. The length of the fractured fragments was not significantly different between the groups, and fractographic analysis by SEM detected the typical topographic features of separated thermally treated NiTi instrument surfaces.