Explore the vast range of titles available.

Extrusion-based printing enables simplified and economic manufacturing of surgical guides for oral implant placement. Therefore, the cytotoxicity of a biocopolyester (BE) and a polypropylene (PP), intended for the fused filament fabrication of surgical guides was evaluated. For comparison, a medically certified resin based on methacrylic esters (ME) was printed by stereolithography (n = 18 each group). Human gingival keratinocytes (HGK) were exposed to eluates of the tested materials and an impedance measurement and a tetrazolium assay (MTT) were performed. Modulations in gene expression were analyzed by quantitative PCR. One-way ANOVA with post-hoc Tukey tests were applied. None of the materials exceeded the threshold for cytotoxicity (< 70% viability in MTT) according to ISO 10993-5:2009. The impedance-based cell indices for PP and BE, reflecting cell proliferation, showed little deviations from the control, while ME caused a reduction of up to 45% after 72 h. PCR analysis after 72 h revealed only marginal modulations caused by BE while PP induced a down-regulation of genes encoding for inflammation and apoptosis ( p  < 0.05). In contrast, the 72 h ME eluate caused an up-regulation of these genes ( p  < 0.01). All evaluated materials can be considered biocompatible in vitro for short-term application. However, long-term contact to ME might induce (pro-)apoptotic/(pro-)inflammatory responses in HGK.

Objectives With direct and indirect digitalisation, two access points to CAD/CAM-generated restorations are available. The aim of this study was to compare the accuracy of the single steps of both approaches by comparing construction datasets using a new methodology. Material and method Twelve test datasets were generated in vitro (1) with the Lava Chairside Oral Scanner (COS) (2) by digitizing polyether impressions (IMP) and (3) by scanning the referring gypsum cast by the Lava Scan ST laboratory scanner (ST) at a time. Using an inspection software, these datasets were superimposed by a best fit algorithm with the reference dataset (REF), gained from industrial computed tomography, and divergences were analysed. Results On the basis of average positive and negative deviations between test- and REF datasets, it could be shown that direct digitalisation accomplished the most accurate results (COS, 17 μm/−13 μm; SD ± 19 μm), followed by digitized polyether impression (IMP, 23 μm/−22 μm; SD ± 31 μm) and indirect digitalisation (ST, 36 μm/−35 μm; SD ± 52 μm). The mean absolute values of Euclidean distances showed the least values for COS (15 μm; SD ± 6 μm), followed by IMP (23 μm; SD ± 9 μm) and ST (36 μm; SD ± 7 μm). The mean negative and mean absolute values of all groups were significantly different. Comparing the mean positive values of the groups, IMP and COS ( p  = 0.082) showed no significant difference, whereas ST and COS, and ST and IMP exhibited statistically significant differences. Conclusions Within the limitations of this in vitro study, the direct digitalisation with Lava C.O.S. showed statistically significantly higher accuracy compared to the conventional procedure of impression taking and indirect digitalisation. Clinical relevance Within the limitations of this study, the method of direct digitalisation seems to have the potential to improve the accuracy of impressions for four-unit FDPs.

Objectives Direct and indirect digitalization offer two options for computer-aided design (CAD)/ computer-aided manufacturing (CAM)-generated restorations. The aim of this study was to evaluate the accuracy of different intraoral scanners and compare them to the process of indirect digitalization. Material and method A titanium testing model was directly digitized 12 times with each intraoral scanner: (1) CS 3500 (CS), (2) Zfx Intrascan (ZFX), (3) CEREC AC Bluecam (BLU), (4) CEREC AC Omnicam (OC) and (5) True Definition (TD). As control, 12 polyether impressions were taken and the referring plaster casts were digitized indirectly with the D-810 laboratory scanner (CON). The accuracy (trueness/precision) of the datasets was evaluated by an analysing software (Geomagic Qualify 12.1) using a “best fit alignment” of the datasets with a highly accurate reference dataset of the testing model, received from industrial computed tomography. Results Direct digitalization using the TD showed the significant highest overall “trueness”, followed by CS. Both performed better than CON. BLU, ZFX and OC showed higher differences from the reference dataset than CON. Regarding the overall “precision”, the CS 3500 intraoral scanner and the True Definition showed the best performance. CON, BLU and OC resulted in significantly higher precision than ZFX did. Conclusions Within the limitations of this in vitro study, the accuracy of the ascertained datasets was dependent on the scanning system. The direct digitalization was not superior to indirect digitalization for all tested systems. Clinical relevance Regarding the accuracy, all tested intraoral scanning technologies seem to be able to reproduce a single quadrant within clinical acceptable accuracy. However, differences were detected between the tested systems.

The rapid advancement of three-dimensional (3D) printing in dentistry has prompted comparisons between the mechanical properties of polylactic acid (PLA) samples fabricated using material extrusion (MEx) and resin samples produced using digital light processing (DLP). This study aims to assess the potential of replacing resin-based models with PLA models in clinical settings by evaluating the mechanical properties and accuracy of MEx-printed PLA and DLP-printed resin samples. The investigated materials include pure PLA, a PLA composite containing gypsum, and a clinically approved resin material. Strength and hardness tests were conducted using custom-made samples measuring 16 × 4 × 2 mm 3 . Additionally, oral cavity scans were used to generate oral models for each material to assess their accuracy, trueness, and precision. The results indicated that pure PLA exhibited the highest flexural modulus (2055 ± 217.70 MPa) and compression modulus (2.40 ± 0.14 GPa). The PLA-Gypsum composite displayed the highest hardness (19.48 ± 2.12 HV1). As for the trueness of the oral models, there were no statistically significant differences between the models made from the three materials. However, the PLA-Gypsum composite demonstrated the best precision (23.84 ± 4.12 μm). These findings suggest that both PLA materials have significant potential to replace DLP-produced resin models in the clinical applications. Graphical Abstract

New monolithic multi-layered zirconia restorations are gaining popularity due to their excellent aesthetic properties. However, current knowledge of these newest multi-layer ceramics in terms of mechanical properties is scarce. Three monolithic, multi-layered zirconia materials (Katana, Kuraray Noritake, Japan) were selected for comparison: High Translucent Multi-layered zirconia (HTML), Super Translucent Multi-layered zirconia (STML) and Ultra Translucent Multi-layered zirconia (UTML). Fifteen specimens per group were cut from pre-sintered blocs in each of the four layers (L1, L2, L3, L4) and in different thicknesses (0.4 mm, 0.8 mm and 1.2 mm). Critical fracture load (Fcf) was recorded in 3-point-bending. Flexural strength (σ) in MPa, Vickers hardness (HV) in N/mm2, fracture toughness (KIc) in MPa*m1/2, Weibull Modulus (m) and characteristic Weibull strength (σw) in MPa were assessed. Statistical analysis was performed using ANOVA analysis. FS and KIc were significantly higher (p < 0.05) for Katana™ HTML (652.85 ± 143.76–887.64 ± 118.95/4.25 ± 0.43–5.01 ± 0.81) in comparison to Katana™ STML (280.17 ± 83.41–435.95 ± 73.58/3.06 ± 0.27–3.84 ± 0.47) and UTML (258.25 ± 109.98–331.26 ± 56.86/2.35 ± 0.31–2.94 ± 0.33), with no significant differences between layers and layer thicknesses. The range of indications should be carefully considered when selecting the type of monolithic zirconia for fabrication of dental restorations, as materials widely differ in mechanical properties.

The topical literature lacks any comparison between stereolithography (SLA) and direct light processing (DLP) printing methods with regard to the accuracy of complete denture base fabrication, thereby utilizing materials certified for this purpose. In order to investigate this aspect, 15 denture bases were printed with SLA and DLP methods using three build angles: 0°, 45° and 90°. The dentures were digitalized using a laboratory scanner (D2000, 3Shape) and analyzed in analyzing software (Geomagic Control X, 3D systems). Differences between 3D datasets were measured using the root mean square (RMS) value for trueness and precision and mean and maximum deviations were obtained for each denture base. The data were statistically analyzed using two-way ANOVA and Tukey’s multiple comparison test. A heat map was generated to display the locations of the deviations within the intaglio surface. The overall tendency indicated that SLA denture bases had significantly higher trueness for most build angles compared to DLP (p < 0.001). The 90° build angle may provide the best trueness for both SLA and DLP. With regard to precision, statistically significant differences were found in the build angles only. Higher precision was revealed in the DLP angle of 0° in comparison to the 45° and 90° angles.

Objectives To evaluate the esthetic and functional rehabilitation of single implants delivering the final crown during second-stage surgery. Materials and methods In 26 single-tooth implants, the impressions were taken immediately after implant placement to fabricate the final crowns. During the second-stage surgery, the screw-retained hybrid crowns were delivered. Six months to 3 years after placement of the crown, a modified pink esthetic score (PES) was measured. Additionally, the number of treatment sessions was recorded. The mesial and distal contact points and the static and dynamic occlusion were examined. Patients’ satisfaction was measured using a questionnaire. Results In this retrospective study, 21 posterior and 5 anterior implants were included. The average pink esthetic score was 11.3 out of 14. The most frequent limitations were incomplete papillae and deficits of the alveolar ridge. The average number of appointments was three, consisting of impression taking and surgery consent, implant placement, and crown delivery. Average patients’ satisfaction was 46.7 out of 50 and thus, extremely high. Conclusions The presented approach allows the second-stage surgery and delivery of the final restoration for single-tooth implants in the same session. As the peri-implant mucosa is adapted to the final restoration in the first place, a more natural emergence profile is achieved. However, there is an increasing risk for reduced or missing papillae. Patients’ satisfaction is generally very high. Clinical relevance A method for direct definitive prosthetic restoration during the exposure of single-tooth implants is examined, advantages and disadvantages will be described, and patient acceptance is validated.

For restoration of extensively damaged teeth preprosthetic treatment measures are necessary. Crown lengthening and extrusion affect the prospective crown-root ratio (CRR). The subject of this in vitro study was to compute CRRs for both treatment approaches. 120 human maxillary central extracted incisors were measured. Measurements were calculated for five treatment groups: C (control), E-2 mm (extrusion of 2 mm), E-4 mm (extrusion of 4 mm), CL-2 mm (crown lengthening of 2 mm), and CL-4 mm (crown lengthening of 4 mm). Tooth (TL), root (RL), and crown lengths (CL) were measured from mesial (m) and facial (f) cemento-enamel junction (CEJ), and respective anatomic (CRR) and effective crown-root ratios (eCRR) were calculated. Following CRR values were computed for C: CRR-m = 0.4 ± 0.1, CRR-f = 0.7 ± 0.1. All crown-root ratios were lower (more favourable) for extrusion compared to crown lengthening ( p  < 0.001). ECRRs were higher than anatomic CRRs. CRR at mesial CEJ was significantly lower than CRR with facial CEJ as reference ( p  < 0.001). Mesial measurement-based calculations of CRR typically based on radiographic images should be interpreted with caution as they underestimate the eCRR. CRR can be expected as lower, i.e. more favourable, when teeth are extruded than crown lengthened.

This narrative review aims to analyze sex-specific differences in oral health, examine hormonal influences in women during puberty, pregnancy, and menopause, and compare oral health behaviors between men and women. Articles were selected based on: (1) sex-specific aspects of oral diseases, (2) hormonal influences on oral health, (3) comparative analyses between sexes, and (4) sex-disaggregated data on oral disease prevalence. Women experience hormonal vulnerabilities with estrogen deficiency causing xerostomia, mucosal atrophy, and increased caries susceptibility, showing parallels between oral and vaginal mucosa. Men demonstrate higher periodontitis prevalence (57% vs. 38%), utilize preventive services one-third less frequently, and show higher smoking rates (67% vs. 42%) and traumatic dental injuries (2:1 ratio). Women maintain better oral hygiene and treatment adherence. Sex-specific factors affecting both sexes remain unconsidered in dental practice. Women need targeted interventions during hormonal transitions, while men require improved preventive care engagement. Future research integrating sex-specific considerations is required to enable personalized oral health approaches for both sexes.

ObjectivesThis in-vitro study was performed to compare the contact wear, fracture strength and failure mode of implant-supported all-ceramic single crowns manufactured with various fabrication and fixation concepts.Materials and methodsFifty dental implants (Conelog Ø 4,3mm/L11mm, Camlog Biotechnologies AG) were embedded and treated with all-ceramic molar single-crowns. Three groups received hand-layered zirconia crowns (IPS e.max Ceram/ IPS e.max ZirCAD, Ivoclar Vivadent AG): CZL (cement-retained zirconia-based layered) group crowns were cemented conventionally, SZL (screw-retained zirconia-based layered) group crowns were screw-retained, MZL (modified zirconia-based layered) group crowns showed a different coping design with screw retention. The specimens of SST (screw-retained sintering-technique) and SFL (screw-retained full-contour lithium-disilicate) group were CAD/CAM (Computer-aided design/computer-aided manufacturing) fabricated in the sintering technique (IPS e.max ZirCAD/IPS e.max CAD, Ivoclar Vivadent AG) and full-contour of lithium disilicate (IPS e.max CAD, Ivoclar Vivadent AG) respectively and screw-retained. All specimens underwent artificial aging, load until failure and a scanning electron microscopy (SEM) analysis. The received data were statistically compared (one-way ANOVA; Student-Newman-Keuls test; Mann-Whitney U-test) at a significance level of 5%.ResultsMouth-motion fatigue testing caused two abutment fractures (SST group and SZL group) and two chipping events (CZL group). Specimens of MZL group showed statistically significant less contact wear compared to the other groups (p<0.001). There was no statistical difference between the groups in terms of the maximum fracture load. SEM-analysis showed a more homogenous structure and surface of CAD/CAM fabricated specimens towards manually veneered components.ConclusionsThe mode of retention did not influence the fracture resistance but the failure patterns of the specimens. CAD/CAM milled lithium-disilicate crowns seemed to be a preserving factor for dental implants.Clinical relevanceThe mode of retention and veneering influences the mechanical performance of implant-supported single crowns.