Modular Digital and 3D-Printed Dental Models with Applicability in Dental Education.

Background and Objectives: The ever more complex modern dental education requires permanent adaptation to expanding medical knowledge and new advancements in digital technologies as well as intensification of interdisciplinary collaboration. Our study presents a newly developed computerized method allowing virtual case simulation on modular digital dental models and 3D-printing of the obtained digital models; additionally, undergraduate dental students' opinion on the advanced method is investigated in this paper. Materials and Methods: Based on the digitalization of didactic dental models, the proposed method generates modular digital dental models that can be easily converted into different types of partial edentulism scenarios, thus allowing the development of a digital library. Three-dimensionally printed simulated dental models can subsequently be manufactured based on the previously obtained digital models. The opinion of a group of undergraduate dental students (n = 205) on the proposed method was assessed via a questionnaire, administered as a Google form, sent via email. Results: The modular digital models allow students to perform repeated virtual simulations of any possible partial edentulism cases, to project 3D virtual treatment plans and to observe the subtle differences between diverse teeth preparations; the resulting 3D-printed models could be used in students' practical training. The proposed method received positive feedback from the undergraduate students. Conclusions: The advanced method is adequate for dental students' training, enabling the gradual design of modular digital dental models with partial edentulism, from simple to complex cases, and the hands-on training on corresponding 3D-printed dental models.

Oral Habits during the Lockdown from the SARS-CoV-2 Pandemic in the Romanian Population.

Background and Objectives: The SARS-CoV-2 pandemic led to changes in population daily patterns. In order to adapt oral health promotion measures for future similar conditions, the main objective of the study was to assess changes in dental hygiene and eating and smoking habits during the government lockdown in Romania. Materials and Methods: The cross-sectional study was conducted immediately after the end of the lockdown and consisted of 800 adult subjects. Data collection was done via an online survey. Participants were divided into two groups: non-medical/dental practitioners (N-M/D group) and medical/dental practitioners (M/D group). Results: An increased use of dental floss from 27% (pre-lockdown) to 30.5% (during lockdown) was identified in the M/D group, while the manual toothbrush usage increased to 64.8% (during lockdown) from 61.7% (pre-lockdown) in the N-MD/group. No significant differences regarding toothbrushing frequency were observed in either group. A change in the number of daily snacks was identified in both groups (3-4 snacks per day: from 11% to 20.2% in the N-M/D group, from 13.1% to 22.2% in the M/D group). The consumption of sweets as a preferred snack was also noticed. A decrease of tobacco consumers was assessed in the lockdown period (from 66.6% to 60.4% in the M/D group, from 68.5% to 61.9% in the N-/M/D group). Conclusions: Oral habits were changed during the pandemic lockdown through the increase in the frequency of the consumption of snacks and sweets and the decrease in frequency of smokers. Only minor changes were observed in oral hygiene.

Analysis of Gingival Fibroblasts Behaviour in the Presence of 3D-Printed versus Milled Methacrylate-Based Dental Resins-Do We Have a Winner?

Computer-aided design and computer-aided manufacturing (CAD/CAM) techniques are based on either subtractive (milling prefabricated blocks) or additive (3D printing) methods, and both are used for obtaining dentistry materials. Our in vitro study aimed to investigate the behavior of human gingival fibroblasts exposed to methacrylate (MA)-based CAD/CAM milled samples in comparison with that of MA-based 3D-printed samples to better elucidate the mechanisms of cell adaptability and survival. The proliferation of human gingival fibroblasts was measured after 2 and 24 h of incubation in the presence of these samples using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, and the membrane integrity was assessed through the lactate dehydrogenase release. The level of reactive oxygen species, expression of autophagy-related protein LC3B-I, and detection of GSH and caspase 3/7 were evaluated by fluorescence staining. The MMP-2 levels were measured using a Milliplex MAP kit. The incubation with MA-based 3D-printed samples significantly reduced the viability, by 16% and 28% from control after 2 and 24 h, respectively. There was a 25% and 55% decrease in the GSH level from control after 24 h of incubation with the CAD/CAM milled and 3D-printed samples, respectively. In addition, higher levels of LC3B-I and MMP-2 were obtained after 24 h of incubation with the MA-based 3D samples compared to the CAD/CAM milled ones. Therefore, our results outline that the MA-CAD/CAM milled samples displayed good biocompatibility during 24-h exposure, while MA-3D resins are proper for short-term utilization (less than 24 h).

Influence of Direct Coronal Restoration Materials on the Fracture Resistance of Endodontically Treated Premolars: An In Vitro Study.

(1) Background: The long-term survival of an endodontically treated tooth depends on a successful root canal treatment as well as an adequate definitive coronal restoration. This study aimed to evaluate the strength of endodontically treated premolars with mesial-occlusal-distal (MOD) cavity preparation restored with different direct coronal restoration materials but from the same manufacturer against fracture. (2) Methods: sixty intact premolars were selected and placed into five groups (n = 12): G1-intact teeth, G2-endodontic treatment and unrestored MOD cavities, G3-endodontic treatment and MOD cavities restored with Tetric PowerFlow and Tetric EvoCeram, G4-endodontic treatment and MOD cavities restored with Multicore Flow and Tetric EvoCeram, and G5-endodontic treatment and MOD cavities restored with Multicore Flow. The specimens were subjected to an axial compression load at a speed of 1.6 mm/min and optically inspected before and after with a stereomicroscope. For each premolars group, the following data were recorded: the compression resistance, the compressive strength, and the maximum force supported. The microstructure of the samples after the compression test was analyzed using scanning electron microscopy (SEM). (3) Results: statistical analysis (ANOVA and Tukey test) showed that there was a statistically significant difference between G1 and the other groups. Even though there was no statistically significant difference between the restored groups, a better mechanical behavior was registered within the G3. (4) Conclusions: this in vitro study indicated that none of the materials used can lead to a higher or at least similar fracture resistance as the intact teeth. The coronal restoration only with nano-hybrid composites may lead to a higher therapeutic benefit for the fracture-susceptible premolars.

Qualitative assessment of the removable denture microbiome.

Introduction: Assessment of the denture plaque can provide a valuable report regarding the oral health of geriatric patients and the oral hygiene habits in this population group. Focusing on the current research gap on this topic in Romania, our research aims to highlight the microbial plaque on the different surfaces and types of removable poly(methyl methacrylate) (PMMA) prostheses to qualitatively evaluate the microbial species, and to assess the combined effect of mechanical and chemical cleaning of dentures on the prosthetic microbiome. Methods: The prosthetic plaque from four denture wearers was identified with a UV activated fluorescent revealer and digitally photographed. Swab samples according to a certain hygiene protocol were cultured on three different growth media such as blood agar (BA), bromothymol blue lactose agar (AABTL) and Sabouraud dextrose agar (SDA). Results: Denture plaque was variably distributed on the surface of the prostheses. Regardless of the denture type (conventional complete denture, tooth or implant supported overdenture, removable partial denture) the microbial plaque was identified at the retentive areas, especially at interdental spaces. The main plaque deposition areas were the vestibular incline of the labial flange of the maxillary denture and the lingual incline of the posterior lingual flange of the mandibular denture. The prosthetic microbiome consisted of pathogenic Gram-positive aerobes (Streptococcus spp. and coagulase-negative Staphylococcus spp.), Gram-positive anaerobes (Actinomyces spp. and Klebsiella spp.) as well as subspecies of fungi of the genus Candida. Conclusions: Despite its poor variety, the denture microbiome in the investigated cases hosts colonies with high pathogenic potential. Some areas of the prostheses are more likely to accumulate dental plaque. Dentists should insist through more regular checks of the patients and their caregivers on ensuring the biocontrol of the dentures, especially in frail geriatric patients exposed to greater risks related to general health.

Microscopic and statistical evaluation of the marginal defects of composite restorations: in vitro studies.

This study aimed to evaluate the quality of dental restorations using laboratory microscopic techniques, focusing on the positioning of restorations relative to cavity edges and identifying common errors, such as incomplete or excessive coronal restorations. A total of 41 extracted lateral teeth, previously treated in vivo with Class I or II composites, were analyzed. Thirty-three of these teeth were sectioned medio-distally or buccal-orally and examined under a research laboratory microscope. Marginal areas were measured using eyepieces with a graduated scale and calibration slide, and a frequency statistical analysis was conducted. The analysis revealed that the teeth had fractious edges, deficient marginal closure, excess composite, incorrectly restored occlusal cusps, and marginal adaptation errors, with approximately half of these errors involving excess material. It was observed that restoration procedures in distal areas are particularly challenging, and clinical errors with excess material occur more frequently than those with a deficit. These findings underscore the need for improved techniques and precision in dental restorations to minimize such errors.

Optical microscopy evaluation of root canal filling removal by beginner operators in posterior teeth.

This study analyzed the effectiveness of root canal filling removal in lower molars performed by beginner operators using optical microscopy. A total of 55 mandibular first and second molars with mesial roots exhibiting an average curvature of 10-20° were selected based on preoperative radiographs. Instrumentation was done with ProTaper Gold (Dentsply Sirona) up to F2 (25/.08), using 2ml of 2.5% NaOCl irrigation solution after each file. Root canal obturation was performed using gutta-percha points with cold lateral condensation and Sealapex (Kerr Dental). Coronal fillings were made with composite resin and stored in distilled water for two years. Removal of the root canal fillings was performed with AF Retreatment Rotary (AFRR) and AF Blue R3 (AFBR3) (Fanta Dental Materials) under reciprocating motion with 2.5% NaOCl irrigation. Cross-sections of the coronal, middle, and apical thirds were analyzed at 40x magnification using a STEINDORFF POL microscope with a digital camera. Image analysis was conducted using Image J software, version 1.54, to determine the efficiency of root canal filling removal by percentage. Statistical analysis via one-way ANOVA revealed significant differences between distal and mesial roots (P < 0.05). Specifically, for mesial roots, the removal efficiency was 70.65% in the coronal third, 54.66% in the middle third, and 21.32% in the apical third. Significant difficulties were noted due to fractured files, calcifications, and debris accumulation in the isthmuses. The study concluded that the protocol using Fanta files demonstrated significant differences in removal efficiency correlated with root curvature, compounded by the inexperience of beginner operators. The findings highlight the challenges faced by novice practitioners in achieving effective root canal filling removal.

Aspects Regarding Sustainability among Private Dental Practitioners from Bucharest, Romania: A Pilot Study.

Oral health professionals' knowledge of sustainability is essential for promoting environmental protection in dental healthcare. This pilot study involved an online survey addressed to 70 dental private practitioners from Bucharest, Romania, to evaluate their awareness of the concept of sustainability in dentistry. The performed statistical analysis revealed that 41.4% of the participants were well aware of sustainability in dentistry, with older participants demonstrating significantly higher levels of such awareness (p = 0.001). Sustainability awareness among participants correlates positively with their knowledge of the negative environmental impacts of dental activity (p < 0.001) and with the concern for sustainable dentistry implementation in their workplace (p = 0.037). Improper biohazardous waste disposal was identified as the primary cause of negative environmental impact of dental practices by 87.1% of participants. Installing high energy-efficient dental equipment was selected as the most important action to implement sustainability in participants' dental practices (64.3%). Overall, 51.4% of the participants reported that the COVID-19 pandemic had a medium impact on their dental activity in terms of sustainability. Our study found that participants have a moderate level of awareness regarding sustainability in dentistry, highlighting the need for education on sustainability for oral health professionals.

Perceptions and Expectations of Academic Staff in Bucharest towards the COVID-19 Pandemic Impact on Dental Education.

Dental education was severely challenged by the COVID-19 pandemic worldwide. The evaluation of the viewpoint of the dental teachers of the Faculty of Dentistry at "Carol Davila" University of Medicine and Pharmacy in Bucharest, Romania, on these exceptional circumstances' consequences was the objective of this paper. A cross-sectional study was conducted in April 2022, on the academic staff who reported their perceptions of the emotional and educational impact of the pandemic by completing a Google Forms questionnaire. Although a significant emotional impact of the pandemic was reported by over a third of the participants (31.2%), most of them being teachers of fifth-year dental students (p = 0.019), the perceived stress had an impact on the teaching performance in few of them (14%), the quality of sleep remaining unaffected in most of them (53.7%), whereas the level of anxiety was low (57%). An educational impact regarding the techno difficulties during the online transition was mentioned by few respondents (16.1%), with male teaching staff facing the fewest problems (p = 0.024), as well as low levels of difficulties in transmitting academic information (11.9), with men also being the most unaffected (p = 0.006). More than half of the participants (59.1%) rather see digital and/or virtual education during the pandemic as having adverse effects on the educational system, the most sceptical being teachers of the fifth (p = 0.001) and sixth years (p = 0.001). The COVID-19 pandemic affected the academic staff of the Faculty of Dentistry at "Carol Davila" University of Medicine and Pharmacy in Bucharest, Romania, not only at a personal level but also at a professional, pedagogical one, due to the introduction of the online teaching system followed by the hybrid one. Age group, gender, and teaching year differentiated the degree of emotional and educational impairment.

The Multidimensional Vaccine Hesitancy Scale: A Validation Study.

Vaccination hesitancy (VH) is a phenomenon which increases the occurrence of vaccine-preventable diseases. The study tests the validity of the Multidimensional Vaccine Hesitancy Scale (MVHS) in the case of a sample of Romanian adults (n = 528; Meanage = 30.57). The latter filled in an online cross-sectional survey. The construct validity of MVHS was assessed by using confirmatory factor analysis (CFA), the reliability was calculated by using the internal consistency, and the convergent and discriminant validity was assessed by using the composite reliability (CR), and average variance extracted (AVE). The obtained model was invariant across gender. The structural equation model was designed for predictive validity by using the partial least square method (PLS-SEM) which analyses the relation between the MVHS dimensions and the vaccination willingness. The results show support for the 8-factor structure of the scale (χ2/df = 2.48; CFI = 0.95; RMSEA = 0.053). The Cronbach's coefficients α > 0.70; McDonald's ω > 0.70 and CR > 0.80 have very good values. The structural equation model shows that there are more dimensions of the scale which predict vaccination hesitancy in various types of vaccines­the main predictors remain the dimensions of health risk and healthy condition. The study's conclusion led to the idea that the MVHS is suitable for medical practice and for research on the analysis of vaccination behaviours and intentions.

Prosthetic Materials Used for Implant-Supported Restorations and Their Biochemical Oral Interactions: A Narrative Review.

The purpose of this study is to outline relevant elements regarding the biochemical interactions between prosthetic materials used for obtaining implant-supported restorations and the oral environment. Implant-supported prostheses have seen unprecedented development in recent years, benefiting from the emergence of both new prosthetic materials (with increased biocompatibility and very good mechanical behavior), and computerized manufacturing technologies, which offer predictability, accuracy, and reproducibility. On the other hand, the quality of conventional materials for obtaining implant-supported prostheses is acknowledged, as they have already proven their clinical performance. The properties of PMMA (poly (methyl methacrylate))-which is a representative interim material frequently used in prosthodontics-and of PEEK (polyether ether ketone)-a biomaterial which is placed on the border between interim and final prosthetic use-are highlighted in order to illustrate the complex way these materials interact with the oral environment. In regard to definitive prosthetic materials used for obtaining implant-supported prostheses, emphasis is placed on zirconia-based ceramics. Zirconia exhibits several distinctive advantages (excellent aesthetics, good mechanical behavior, biocompatibility), through which its clinical applicability has become increasingly wide. Zirconia's interaction with the oral environment (fibroblasts, osteoblasts, dental pulp cells, macrophages) is presented in a relevant synthesis, thus revealing its good biocompatibility.

Compressive and Flexural Strength of 3D-Printed and Conventional Resins Designated for Interim Fixed Dental Prostheses: An In Vitro Comparison.

A provisionalization sequence is essential for obtaining a predictable final prosthetic outcome. An assessment of the mechanical behavior of interim prosthetic materials could orient clinicians towards selecting an appropriate material for each clinical case. The aim of this study was to comparatively evaluate the mechanical behavior-with compressive and three-point flexural tests-of certain 3D-printed and conventional resins used to obtain interim fixed dental prostheses. Four interim resin materials were investigated: two 3D-printed resins and two conventional resins (an auto-polymerized resin and a pressure/heat-cured acrylic resin). Cylindrically shaped samples (25 × 25 mm/diameter × height) were obtained for the compression tests and bar-shaped samples (80 × 20 × 5 mm/length × width × thickness) were produced for the flexural tests, observing the producers' recommendations. The resulting 40 resin samples were subjected to mechanical tests using a universal testing machine. Additionally, a fractographic analysis of failed samples in bending was performed. The results showed that the additive manufactured samples exhibited higher elastic moduli (2.4 ± 0.02 GPa and 2.6 ± 0.18 GPa) than the conventional samples (1.3 ± 0.19 GPa and 1.3 ± 0.38 GPa), as well as a higher average bending strength (141 ± 17 MPa and 143 ± 15 MPa) when compared to the conventional samples (88 ± 10 MPa and 76 ± 7 MPa); the results also suggested that the materials were more homogenous when produced via additive manufacturing.

Patients' Perspective on Their Experience of Dental Treatments Covered by Public Health Insurance in Romania-A Pilot Study.

Although the aims of any public health coverage are prevention, diagnosis, treatment, rehabilitation, and maintenance, dental services are hardly ever included in services. The goal of our pilot study is to assess the perspective of a group of adult patients on their covered dental treatments. The present cross-sectional study was conducted on 140 patients who reported their perception by filling in a questionnaire. All the collected data were statistically analyzed using IBM SPSS Statistics 25. Most of the subjects (40.7%, n = 57) were treatment oriented, visiting the dentist only in an emergency situation. A total of 40.7% (n = 57) of the participants stated that all the dental treatments had coverage and 22.8% (n = 13) had to split their treatment plan because of the insurance budget limit. The subjects who had chosen covered dental services because they considered it was a right they should benefit from (53.7%, n = 22) and those who had chosen covered dental services because of financial reasons (29.3%, n = 12) were more frequently unsatisfied with the types of covered dental services. The reduced level of satisfaction was associated mainly with the list of dental procedures accepted for coverage and also with younger and highly educated patients. For a more accurate description, the present study should be completed by future studies not only on a representative population at national level, but also by assessing the perspective of dental professionals.

Molecular Interactions between Saliva and Dental Composites Resins: A Way Forward.

Dentin and enamel loss related to trauma or especially caries is one of the most common pathological issues in dentistry that requires restoration of the teeth by using materials with appropriate properties. The composite resins represent dental materials with significant importance in today's dentistry, presenting important qualities, including their mechanical behavior and excellent aesthetics. This paper focuses on the saliva interactions with these materials and on their biocompatibility, which is continuously improved in the new generations of resin-based composites. Starting from the elements involved on the molecular landscape of the dental caries process, the paper presents certain strategies for obtaining more advanced new dental composite resins, as follows: suppression of oral biofilm acids formation, promotion of remineralization process, counteraction of the proteolytic attack, and avoidance of cytotoxic effects; the relation between dental composite resins and salivary oxidative stress biomarkers is also presented in this context.

Biochemical Interaction between Materials Used for Interim Prosthetic Restorations and Saliva.

The purpose of this study was to analyze the oxidative stress level and inflammatory status of saliva in the presence of certain materials used for obtaining interim prosthetic restorations. Four types of interim resin materials were investigated: a pressure/heat-cured acrylic resin (Superpont C+B, SpofaDental a.s Czech Republic, /KaVo Kerr Group), a milled resin (Telio CAD polymethyl methacrylate, Ivoclar Vivadent AG, Liechtenstein), a 3D printed resin (NextDent C&B MFH, NextDent by 3D Systems, the Netherlands), and a pressure/heat-cured micro-filled indirect composite resin (SR Chromasit, Ivoclar Vivadent AG, Liechtenstein). The disk-shaped resin samples (30 mm diameter, 2 mm high) were obtained in line with the producers' recommendations. The resulting resin specimens were incubated with saliva samples collected from twenty healthy volunteers. In order to analyze the antioxidant activity of the tested materials, certain salivary parameters were evaluated before and after incubation: uric acid, gamma glutamyl transferase (GGT), oxidative stress responsive kinase-1 (OXSR-1), and total antioxidant capacity (TAC); the salivary levels of tumor necrosis factor (TNFα) and interleukin-6 (IL-6) (inflammatory markers) were measured as well. The obtained results are overall favorable, showing that the tested materials did not cause significant changes in the salivary oxidative stress level and did not influence the inflammatory salivary status.