Barbara Cvikl

Objectives: CBCT provides insights into the presence of an additional root canal in maxillary first molars. Since the maxillary first molar is one of the teeth most likely requiring root canal treatment, and young people are more sensitive to radiation exposure, this study aimed to evaluate the prevalence of MB2 canals in healthy, untreated maxillary first molars using CBCT. Methods: CBCT scans of maxillary first molars of 167 patients were categorized according to the classification systems of Wein, Vertucci, and Ahmed. The number of root canals and the presence of an MB2 canal were analyzed descriptively. The associations between the presence of an MB2 canal and various factors, including gender, position in the dental arch, and age group, were examined using a chi-squared test at a significance level of P < .05. All analyses were performed using SPSS. Results: A second mesiobuccal root canal was found in 63% (Weine) and 66% (Vertucci) of the examined maxillary first molars, respectively. Significantly fewer women exhibited a second mesiobuccal root canal compared to men. No statistical differences were observed regarding the position in the dental arch or the different age groups. The most frequently observed root canal morphologies were Vertucci Type I and IV (34% each), followed by Type II (23%), Type VI (6%), Type V (2%), and Type III (1%). In the Weine classification, Types I and II (35% each) were most common, followed by Type III (29%) and Type IV (1%). In the Ahmed classification, the most common configuration was 3MB2-2DB1P1. Conclusions: A MB2 canal was present in about two-thirds of maxillary first molars, with significantly lower prevalence in women but no association with tooth position or age. Advances in knowledge: This study provides updated prevalence and morphological data on MB2 canals, showing they occur in about two-thirds of maxillary first molars and differ by gender. These findings may guide future diagnostic approaches and support more targeted use of CBCT in endodontic treatment planning.

Background: Dental stem cells hold significant potential in regenerative medicine due to their multipotency, accessibility, and immunomodulatory effects. Flow cytometry is a critical tool for analyzing these cells, particularly in identifying and characterizing immunomodulatory markers that enhance their clinical applications. This systematic review aims to answer the question: "How does flow cytometry facilitate the identification and characterization of immunomodulatory markers in dental stem cells to enhance their application in regenerative medicine?". Methods: An exhaustive literature search was conducted in PubMed, retrieving 430 studies, of which 284 met inclusion criteria. Studies were selected based on the use of flow cytometry to analyze immunomodulatory markers in dental stem cells, focusing on methodologies, key findings, and challenges. Results: Of the 284 articles, 229 employed flow cytometry, with 115 reporting relevant results. Flow cytometry revealed important insights into the immunological interactions of various dental stem cells, including dental pulp stem cells, stem cells from human exfoliated deciduous teeth, periodontal ligament stem cells, and stem cells from the apical papilla, by identifying and characterizing immunomodulatory markers such as PD-L1, IDO, and TGF-β1. Conclusions: Flow cytometry is essential for advancing the understanding of dental stem cells' immunomodulatory properties. Standardization of methodologies is required to overcome technical challenges and enhance the clinical applications of dental stem cells in regenerative medicine and immunotherapy. Graphical

The basic function of toothpastes is biofilm removal in order to prevent caries and gingivitis. Toothpastes should provide maximal fluoride availability, optimal abrasivity, and ingredients that do not interfere with fluoride release but should have additional beneficial effects. Further, the effect on cells of the oral cavity is of the utmost importance. We investigated several biological parameters of a new toothpaste (AirFlow-AF) that contains fluoride, xylitol and erythritol but no sodium lauryl sulfate and compared them to commercially available toothpastes (Zendium-Ze, Sensodyne-Se, OdolMed-OM, OralB-OB). The half lethal concentration (LC50) as well as the proliferation behavior on gingival (GF), periodontal ligament (PDL), and mouse fibroblast cells (L929) were was tested. The mean LC50 values of AF on GF, PDL, and L929 were 16.2, 10.9, and 9.3, respectively. In comparison, the four other toothpastes showed mean LC50 values of 1.5 (OB), 1.2 (OM), 1.4 (Se), and 27.7 (Ze) on GF. Mean LC50 values on PDL and L929 were 1.0 and 0.2 (OB), 3.7 and 0.9 (OM), 1.2 and 0.6 (Se), and 25.4 and 5.6 (Ze), respectively. Proliferation behavior mainly confirmed the LC50 values. While cells after stimulation with AF returned to almost unimpaired proliferation behavior at 6%, cells were still strongly impaired after stimulation with all tested commercially toothpastes. AF showed high biocompatibility with different cell types.

The formation of a physiological biofilm cannot be avoided under normal circumstances. However, the consequences of a supragingivally located biofilm, such as caries, gingivitis and, as a further effect, periodontitis, are relatively easy to avoid. The simplest and most common method used worldwide for the elimination of biofilm is periodic mechanical removal using a toothbrush or similar tools, such as chewing sticks or woods. This method was already used in ancient Egypt, and is still being used today, albeit advanced and improved with the help of toothpastes. Here we give a summary of the most common toothbrushes, highlighting their advantages and disadvantages. Furthermore, we provide an overview of the most common toothpastes, their ingredients, and functions. In addition, the ingredients will be critically evaluated and recommendations given for the use or non-use of certain ingredients for different target groups, such as children, healthy adults, or patients with special needs.

Objectives: The study evaluates the influence of two spacer settings and three resin luting materials on the marginal and internal fit of polymer-infiltrated ceramic network (PICN) material crowns manufactured using a complete digital workflow. Methods: Optical impressions of fifty identical dies were performed using the 3M scanner (software version 5.0.2). Twenty crowns were designed using Ceramill Mind (version 3.4.10.1163), from which ten with spacer setting of 50 μm (G1) and ten with 80 μm (G2). Thirty crowns (spacer setting of 50 μm) were divided into three groups corresponding to the resin materials used as follows: RelyX Unicem (RX), Variolink Esthetic (VLE), and Nexus 3 (NX3). All crowns were milled from Vita Enamic blocks. After micro-CT scanning, absolute marginal discrepancy (AMD), internal gap (IG), total cement space volume (TCV), and marginal porosities (VP) were measured. Results: Significant difference was detected on the VP between the RX and NX3 group (p = 0.033). The mean values of all parameters were the following: AMD (μm): G1 182.6, G2 253.7, RX 210.8, VLE 195.5, NX3 186.6; IG (μm): G1 215.6, G2 173.1, RX 171.1, VLE 198.6, NX3 203; TCV (mm³): G1 22.9, G2 20.49, RX 17.57, VLE 17.49, NX3 20.59; VP (mm³): G1 0.26, G2 0.34, RX 0.32, VLE 0.46, NX3 0.54. Conclusions: Fit of PICN material crowns was not significantly influenced by increasing the spacer settings and cementation with different resin materials. Additionally, RelyX Unicem showed significantly less porosities as compared with Nexus3. Clinical relevance: Both 50 μm and 80 μm virtual spacer settings can be suggested for the manufacture of PICN crowns when Ceramill Mind (version 3.4.10.1163) is used. Furthermore, a self-adhesive system can be recommended for the cementation.

In view of the increasing demand of adult orthodontics for esthetic purposes, adult treatment with brackets has become an important issue. One essential factor for the quality of such treatment is bracket bonding on ceramics. For testing the adhesive bond between the bracket and the ceramic surface it is important to consider the static or cyclic loading that goes along with it. Metallic Brackets were adhesively fixed on zirconia ceramic blocks in a simulated leveling phase using two different primers (Monobond S and Monobond Etch & Prime). Half of the metallic brackets were activated using a 0.14-nickel titanium wire, while the other half remained non-activated. Shear bond testing (SBT) was performed after thermocycling. Furthermore the Adhesive Remnant Index (ARI) was analyzed. SBT resulted in significantly higher shear bond values when Monobond Etch & Prime was used compared to the use of Monobond S. Activation of the brackets did not show different results in comparison to the non-activated brackets. The ARI did not indicate cement remnants on the ceramic surface, regardless of the primer and the activation status. The use of Monobond Etch & Prime has great potential for the bonding of brackets on dental zirconia ceramics.

Development in guided tissue regeneration requires biomaterial testing. 3D cell constructs represent a new approach to bridge the gap between cell culture and animal models. Following the hypothesis that attachment behavior of cells could be observed in toroidal 3D cell constructs, the aim of this study was to evaluate 3D gingival fibroblast (GF) toroids as a simple and feasible in vitro assay to test attachment of oral fibroblasts to collagen membranes. 3D ring-like structures (toroids) were formed from human GF. Hematoxylin-eosin staining was performed with formed GF toroids. Produced GF toroids were seeded onto plastic surfaces or collagen membranes. The morphology was documented at 24 h, 48 h and 72 h after seeding with light and fluorescence microscopy. Toroid vitality was assessed at same time points with a resazurin-based toxicity assay. GF showed normal morphology in toroid hematoxylin-eosin staining. Over 72 h, GF toroids on plastic surfaces stayed unchanged, while GF toroids on collagen membranes showed dilatation. GF toroids on plastic surfaces and collagen membranes were metabolically active over the observed period. Depending on the surface material, 3D GF toroids show different attachment behavior. Thus, GF toroids are suitable as simple assay to study attachment behavior to various biomaterials.

Purpose of this study was to evaluate the accuracy of fit of cemented polymer infiltrated ceramic network (PICN) material crowns manufactured after digital and conventional impression techniques using micro computed tomography (CT). Furthermore to determine the cement space volume and porosities in the cement layer. A molar typodont tooth was prepared for PICN material crowns and replicated thirty times. The dies were randomly divided into three groups of 10 specimens each according to the impression technique: 3M True Definition Scanner (TDS), cara TRIOS (Trios) and Impregum Penta Soft (Impregum). PICN material crowns were milled for each specimen from Vita Enamic blocks and cemented on their respective dies. The absolute marginal discrepancy (AMD), internal fit (IG), total cement space volume (TVC) and marginal porosities (VP) were measured using Micro-CT. Mean and standard deviations values in μm for the AMD were: TDS 140.1 (28.4); Trios 253.7 (56.8); Impregum 220.2 (101.1). IG values in μm: TDS 173.1 (27.7); Trios 222.2 (22.4); Impregum 211.6 (55.9). TVC in mm3: TDS 19.82 (2.9); Trios 23.67 (2.01); Impregum 23.77 (5.09). VP in mm3: TDS 0.38 (0.09); Trios 0.36 (0.10); Impregum 0.51 (0.31). TDS group showed significantly better marginal and internal fit than the Trios group. No difference of the parameters was detected between the Impregum and both digital groups which implies that the digital impression technique is suitable in the manufacturing process of PICN material crowns.