Temporary Root Canal Obturation with a Calcium Hydroxide-Based Dressing: A Randomized Controlled Clinical Trial.

Successful bacterial inactivation or elimination is essential for successful outcomes in endodontics. This study investigated the efficacy of a calcium hydroxide paste (Ca(OH)2) as a temporary medical dressing for 1 week after chemomechanical root canal treatment (CMRCT). Microbiological samples from 26 patients were collected after endodontic emergency treatment as follows: (1) removal of the provisional filling material; (2) CMRCT; (3) irrigation with sodium hypochlorite I (3%); (4) medicinal insertion of Ca(OH)2; and (5) irrigation with sodium hypochlorite II (3%). A microbiological examination was carried out after the specimens had been taken from the root canals via saline and sterile paper points. CMRCT resulted in a significant reduction in total bacterial load (TBL) in the root canal (p < 0.05). Additional irrigation (3) resulted in a further significant reduction in TBL (p < 0.05). In contrast, Ca(OH)2 medication did not prevent the bacterial load from returning to the previous level immediately after CMRCT, but did not increase above that level either (p < 0.05). However, the increase in TBL was significant (p < 0.05) in comparison with the disinfection groups (I/II). Administration of Ca(OH)2 for 1 week shows that in combination with an additional disinfection procedure, an increase in TBL must be expected, but not above the level of conditions after CMRCT.

[NKLZ 2.0: the further development of the National Competence-Based Learning Objectives Catalogue for Dentistry as a basis for the design of the new licensing regulations]. / NKLZ 2.0: Die Weiterentwicklung des Nationalen Kompetenzbasierten Lernzielkatalogs Zahnmedizin als Basis für die Ausgestaltung der neuen Approbationsordnung.

The National Competence-Based Catalogue of Learning Objectives in Dentistry (NKLZ) was adopted in 2015 and defines the learning objectives for dental training in Germany. It specifies which competences students should acquire and serves as a basis for the curricular design of the study programme, examinations and teaching materials. The NKLZ promotes a comprehensive education that includes clinical skills and abilities, professional behaviour and communication skills in addition to specialist knowledge. It contributes to the preparation of future dentists for their profession and standardizes training to ensure quality and comparability.This article describes the background, history, structure and further development of the NKLZ. Currently, the NKLZ is being further developed to version 2.0 in a multi-stage process. Its structure is based on the NKLM 2.0, the National Competence-Based Learning Objectives Catalogue for Medicine. The aim is to comprehensively map the requirements for the dental licensing regulations.An important prerequisite for the official recognition of the NKLZ as a basic guideline for the training of dentists is that it be anchored in a dental licensing regulation that is to be reformed soon. This creates clarity and liability for teachers and students. Such an anchoring also enables better coordination between training objectives and the requirements of professional practice. Since the licensing regulations are modified less frequently, the integration of the NKLZ offers the possibility of updating and adapting the catalogue of learning objectives in a structured and regulated manner. This ensures that training is in line with current standards and developments.

Dentin Bonding Performance of Universal Adhesives in Primary Teeth In Vitro.

(1) Background: The aim of this in vitro study was to evaluate the micro-tensile bond strength (µ-TBS) of universal adhesives to primary tooth dentin after different storage periods. (2) Methods: Dentin of 100 extracted primary molars was exposed. Dentin surfaces were bonded with six universal adhesives (Adhese®Universal [AU], All-Bond Universal® [ABU], G-Premio Bond [GPB], iBond®Universal [IBU], Prime&Bond active™ [PBa], and Prime&Bond®NT as control [PBN]) and restored with a resin composite build-up (Filtek™ Z250). After 24 h, 6 months, and 12 months of water storage, specimens were cut into sticks, and µ-TBS was measured and analyzed using one-way ANOVA (p < 0.05) for normal distributions and the Mann-Whitney U-test (p < 0.05) for non-normal distribution. Pretesting failures were recorded as 0 MPa. Fracture modes were analyzed under a fluorescence microscope; interfaces were visualized with SEM/TEM. (3) Results: Compared with the reference group (PBN: 32.5/31.2 MPa after 6/12 months), two adhesives showed a significantly higher bond strength after 6 months (AU: 44.1 MPa, ABU: 40.9 MPa; p < 0.05) and one adhesive after 12 months (AU: 42.9 MPa, p < 0.05). GPB revealed significantly lower bond strengths in all storage groups (16.9/15.5/10.9 MPa after 24 h/6 months/12 months; p < 0.05). AU and IBU did not suffer pre-test-failures [PTF]. (4) Conclusions: After 12 months, PBN, IBU, AU, and GPB showed significantly lower results compared ithw initial µ-TBS, whereas AU revealed the highest µ-TBS and no PTF.

Antimicrobial Effects of Postbiotic Mediators Derived from Lactobacillus rhamnosus GG and Lactobacillus reuteri on Streptococcus mutans.

BACKGROUND: Streptococcus mutans is a major component of dental plaque, contributing to cariogenic biofilm formation and inducing dental caries. Attempts have recently been made to use postbiotic mediators (PMs) to prevent dental caries. This research evaluated the antimicrobial/antibiofilm activity of PMs derived from Lactobacillus rhamnosus GG (LGG) and Lactobacillus reuteri (LR) against S. mutans in vitro. METHODS: PMs were obtained from the Lactobacilli supernatants. The minimum inhibitory concentration, minimum bactericidal concentration, antibiofilm potential, and metabolic activity of PMs against S. mutans were evaluated using CFU/mL, scanning electron microscopy, and XTT (2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide) reduction assay. The expression of gtfB gene as one of the most important genes involved in S. mutans biofilm formation was also measured using qRT-PCR. RESULTS: CFU score was reduced by both PMs, but the reduction was only significant in LGG (p = 0.02). Both PMs caused a significant decrease in the metabolic activity of S. mutans compared with the controls (p ≤ 0.002). S. mutans treated with LGG PMs exhibited more destructive effects than LR PMs (p > 0.05). S. mutans gtfB gene expression was significantly downregulated when treated with the PMs obtained from both LGG and LR (p = 0.01 for both). CONCLUSIONS: We showed that PMs isolated from two Lactobacillus strains inhibited S. mutans biofilm, metabolic activity, and gtfB gene expression. Therefore, these derivatives may be a suitable biofilm-destruction agent against S. mutants. However, the oral environment is a complex ecosystem that needs further investigation.

Marginal Quality and Wear of Bulk-fill Materials for Class-II Restorations in Primary Molars.

PURPOSE: The aim of this in-vitro study was to evaluate the marginal integrity and wear of eight bulk-fill materials in comparison to a compomer in Class-II cavities in primary molars after thermomechanical loading (TML). MATERIALS AND METHODS: Prepared Class-II cavities in 72 extracted primary molars were filled with eight bulk-fill materials. A compomer served as the control group. After water storage (incubator, 28 days, 37°C), samples were subjected to TML (2500 thermal cycles 5°C/55°C; 100,000 load cycles, 50 N, 1.67 Hz). Before and after TML, replicas were made which were used for both SEM analysis of marginal integrity and 3-D wear analysis. Statistical analysis was performed using Kruskal-Wallis and Wilcoxon tests (p < 0.05). RESULTS: A significant reduction in perfect margins was observed for all groups, while marginal gap formation increased (Wilcoxon test, p < 0.02) for all groups but the compomer. Significant interindividual differences were observed between the tested materials regarding marginal integrity (Kruskal-Wallis test, p < 0.05). Wear analysis revealed no significant differences between groups (Kruskal-Wallis test, p > 0.05). CONCLUSION: Some of the bulk-fill materials investigated here achieved better results than the compomer and should be further evaluated clinically.

Effect of Chlorhexidine-containing Etch-and-Rinse Adhesives on Dentin Microtensile Bond Strength after Biological Loading.

PURPOSE: This study compared a 2%-CHX dentin pre-treatment with three CHX adhesives (experimentally admixed 0.1% CHX in primer or bonding agent, or industrially added 0.2% CHX in universal adhesive) by evaluating dentin bond strengths after biological loading in a fully automated artificial mouth model. MATERIALS AND METHODS: The occlusal dentin of 50 freshly extracted human third molars was exposed, and the teeth were randomly assigned to 5 groups according to the adhesive protocol (n = 10): 1. control, Scotchbond Multipurpose (3M Oral Care; CTRL); 2. 2% CHX dentin pre-treatment (DENT); 3. 0.1% CHX experimentally admixed into the primer (PRIM); 4. 0.1% CHX experimentally admixed into the bonding agent (BOND); 5. Peak Universal Bond containing 0.2% CHX (Ultradent; PEAK). The teeth were restored with composite resin. Microtensile bond strength testing (bonding area 0.46 mm2 ± 0.04 mm2, crosshead speed 1 mm/min) was performed after 24-h storage in distilled water (baseline) or after 2-day biological loading with S. mutans (demineralization 1 h / remineralization 5 h). The mode of fracture was recorded and exemplary sticks were evaluated under SEM. RESULTS: CTRL exhibited significantly higher µTBS at baseline in comparison to PRIM (p = 0.000), BOND (p = 0.002), and PEAK (p = 0.000). After undergoing the caries model, CTRL demonstrated significantly lower µTBS compared to DENT (p = 0.000), PRIM (p = 0.008), and PEAK (p = 0.000). The same behavior was observed for BOND vs DENT (p = 0.000), PRIM (p = 0.003), and PEAK (p = 0.001). After biological loading, DENT (p = 0.041), PRIM (p = 0.000), and BOND (p = 0.000) exhibited significantly fewer adhesive fractures than CTRL. CONCLUSIONS: CHX addition to the primer protects dentin bond strength from declining after biological loading. Thus, it may offer some clinical advantage in terms of secondary caries inhibition around composite restorations. However, since loss of adhesion at baseline was less when 2% CHX was used as a dentin pre-treatment, it can be suggested as a safer option. so that bonding is not undermined by potential chemical interactions from CHX with the adhesives.

Factors associated with an increased risk of SARS-CoV-2 infection in healthcare workers in aerosol-generating disciplines.

BACKGROUND: Healthcare workers (HCWs) are at a high risk of SARS-CoV-2 infection due to exposure to potentially infectious material, especially during aerosol-generating procedures (AGP). We aimed to investigate risk factors for SARS-CoV-2 infection among HCWs in medical disciplines with AGP. METHODS: A nationwide questionnaire-based study in private practices and hospital settings was conducted between 12/16/2020 and 01/24/2021. Data on SARS-CoV-2 infections among HCWs and potential risk factors of infection were investigated. RESULTS: 2070 healthcare facilities with 25113 employees were included in the study. The overall infection rate among HCWs was 4.7%. Multivariate analysis showed that regions with higher incidence rates had a significantly increased risk of infection. Furthermore, hospital setting and HCWs in gastrointestinal endoscopy (GIE) had more than double the risk of infection (OR 2.63; 95% CI 2.50-2.82, p<0.01 and OR 2.35; 95% CI 2.25-2.50, p<0.01). For medical facilities who treated confirmed SARS-CoV-2 cases, there was a tendency towards higher risk of infection (OR 1.39; 95% CI 1.11-1.63, p=0.068). CONCLUSION: Both factors within and outside medical facilities appear to be associated with an increased risk of infection among HCWs. Therefore, GIE and healthcare delivery setting were related to increased infection rates. Regions with higher SARS-CoV-2 incidence rates were also significantly associated with increased risk of infection.

Evaluation of direct restorations using the revised FDI criteria: results from a reliability study.

OBJECTIVES: The purpose of this in vitro reliability study was to determine the intra- and inter-examiner agreement of the revised FDI criteria including the categories "fracture of material and retention" (F1) and "caries at restoration margin" (B1). MATERIALS AND METHODS: Forty-nine photographs of direct tooth-coloured posterior (n = 25) and anterior (n = 24) restorations with common deficiencies were included. Ten dental experts repeated the assessment in three blinded rounds. Later, the experts re-evaluated together all photographs and agreed on a reference standard. Statistical analysis included the calculation of Cohen's (Cκ), Fleiss' (Fκ), and weighted Kappa (wκ), the development of a logistic regression with a backward elimination model and Bland/Altman plots. RESULTS: Intra- and inter-examiner reliability exhibited mostly moderate to substantial Cκ, Fκ, and wκ values for posterior restorations (e.g. Intra: F1 Cκ = 0.57, wκ = 0.74; B1 Cκ = 0.57, wκ = 0.73/Inter F1 Fκ = 0.32, wκ = 0.53; B1 Fκ = 0.41, wκ = 0.64) and anterior restorations (e.g. Intra F1 Cκ = 0.63, wκ = 0.76; B1 Cκ = 0.48, wκ = 0.68/Inter F1 Fκ = 0.42, wκ = 0.57; B1 Fκ = 0.40, wκ = 0.51). Logistic regression analyses revealed significant differences between the evaluation rounds, examiners, categories, and tooth type. Both the intra- and inter-examiner reliability increased along with the evaluation rounds. The overall agreement was higher for anterior restorations compared to posterior restorations. CONCLUSIONS: The overall reliability of the revised FDI criteria set was found to be moderate to substantial. CLINICAL RELEVANCE: If properly trained, the revised FDI criteria set are a valid tool to evaluate direct and indirect restorations in a standardized way. However, training and calibration are needed to ensure reliable application.

Revised FDI criteria for evaluating direct and indirect dental restorations-recommendations for its clinical use, interpretation, and reporting.

OBJECTIVES: The FDI criteria for the evaluation of direct and indirect dental restorations were first published in 2007 and updated in 2010. Meanwhile, their scientific use increased steadily, but several questions from users justified some clarification and improvement of the living document. MATERIALS AND METHODS: An expert panel (N = 10) initiated the revision and consensus process that included a kick-off workshop and multiple online meetings by using the Delphi method. During and after each round of discussion, all opinions were collected, and the aggregated summary was presented to the experts aiming to adjust the wording of the criteria as precisely as possible. Finally, the expert panel agreed on the revision. RESULTS: Some categories were redefined, ambiguities were cleared, and the descriptions of all scores were harmonized to cross-link different clinical situations with possible management strategies: reviewing/monitoring (score 1-4), refurbishment/reseal (score 3), repair (score 4), and replacement (score 5). Functional properties (domain F: fracture of material and retention, marginal adaptation, proximal contact, form and contour, occlusion and wear) were now placed at the beginning followed by biological (domain B: caries at restoration margin, hard tissue defects, postoperative hypersensitivity) and aesthetic characteristics (domain A: surface luster and texture, marginal staining, color match). CONCLUSION: The most frequently used eleven categories of the FDI criteria set were revised for better understanding and handling. CLINICAL RELEVANCE: The improved description and structuring of the criteria may help to standardize the evaluation of direct and indirect restorations and may enhance their acceptance by researchers, teachers, and dental practitioners.

Damping Behaviour and Mechanical Properties of Restorative Materials for Primary Teeth.

The energy dissipation capacity and damping ability of restorative materials used to restore deciduous teeth were assessed compared to common mechanical properties. Mechanical properties (flexural strength, modulus of elasticity, modulus of toughness) for Compoglass F, Dyract eXtra, SDR flow, Tetric Evo Ceram, Tetric Evo Ceram Bulk Fill, and Venus Diamond were determined using a 4-point bending test. Vickers hardness and Martens hardness, together with its plastic index (ηITdis), were recorded using instrumented indentation testing. Leeb hardness (HLD) and its deduced energy dissipation data (HLDdis) were likewise determined. The reliability of materials was assessed using Weibull analysis. For common mechanical properties, Venus Diamond always exhibited the significantly highest results and SDR flow the lowest, except for flexural strength. Independently determined damping parameters (modulus of toughness, HLDdis, ηITdis) invariably disclosed the highest values for SDR flow. Composite materials, including SDR flow, showed markedly higher reliabilities (Weibull modulus) than Compoglass F and Dyract eXtra. SDR flow showed pronounced energy dissipation and damping characteristics, making it the most promising material for a biomimetic restoration of viscoelastic dentin structures in deciduous teeth. Future developments in composite technology should implement improved resin structures that facilitate damping effects in artificial restorative materials.

Fourteen years clinical evaluation of leucite-reinforced ceramic inlays luted using two different adhesion strategies.

OBJECTIVES: Aim of the present prospective study was to clinically evaluate the long-term performance of two different luting-materials for leucite-reinforced glass-ceramic inlays/onlays after 14 years. METHODS: A total of 83 IPS-Empress-inlays/onlays were placed in 30 patients. Restorations were luted according to two different strategies: 43 restorations were fixed with a self-adhesive resin-cement (RelyXUnicem, RX), 40 restorations were inserted with VariolinkII-low (SV) after pretreatment with an etch-and-rinse multi-step adhesive. Recalls were performed after two weeks (n=83), two years (n= 82), four years (n=74) and 14 years (n=54). Two independent calibrated examiners evaluated all restorations using modified USPHS-criteria. Statistical analysis was performed using pairwise Mann-Whitney-U-test and Friedman-test (p < 0.05). RESULTS: After 14 years, 54 restorations in 22 patients were evaluated (eight patients equalling 29 inlays not available). Ten restorations had to be replaced (failure rate 12%); four (SV-group) showed bulk fractures and two (RX-group) exhibited marginal fractures at the 14-year recall. Overall, the SV-group revealed significantly better results regarding discoloration of the luting gap (p<0.05) compared to the RX-group. No statistically significant differences were computed between SV and RX for the remaining criteria at the respective recalls (p>0.05). However, statistically significant deteriorations were detected for both luting procedures over 14 years regarding "colour match", "marginal integrity" and "tooth integrity" (p<0.05). CONCLUSIONS: The self-adhesive resin-cement RelyXUnicem showed similar clinical performance to a conventional multi-step luting-procedure after 14 years for most of the test parameters with a slightly inferior performance of RelyXUnicem regarding discoloration of the luting gap. CLINICAL SIGNIFICANCE: The current study presents unique in-vivo long-term data on two adhesion-strategies for indirect ceramic single-tooth restorations. Differences in performance of the two luting methods after being challenged for 14 years in the oral environment are highlighted. However, the overarching survival rate justifies the recommendation of both methods for clinical routine.

Clinical Effectiveness of Restorative Materials for the Restoration of Carious Primary Teeth: An Umbrella Review.

Since untreated dental caries remain a worldwide burden, this umbrella review aimed to assess the quality of evidence on the clinical effectiveness of different restorative materials for the treatment of carious primary teeth. A literature search in electronic bibliographic databases was performed to find systematic reviews with at least two-arm comparisons between restorative materials and a follow-up period ≥12 months. Reviews retrieved were screened; those eligible were selected, and the degree of overlap was calculated using the 'corrected covered area' (CCA). Data were extracted and the risk of bias was assessed using the ROBIS tool. Fourteen systematic reviews with a moderate overlap (6% CCA) were included. All materials studied performed similarly and were equally efficient for the restoration of carious primary teeth. Amalgam and resin composite had the lowest mean failure rate at 24 months while high-viscosity and metal-reinforced glass ionomer cements had the highest. At 36 months, high-viscosity glass ionomer cements showed the highest failure rate with compomer showing the lowest. Most reviews had an unclear risk of bias. Within the limitations of the review, all materials have acceptable mean failure rates and could be recommended for the restoration of carious primary teeth.

SARS-CoV-2 Vaccination Rate and SARS-CoV-2 Infection of Health Care Workers in Aerosol-Generating Medical Disciplines.

Healthcare workers (HCW) who perform aerosol-generating procedures (AGP) are at high risk of SARS-CoV-2 infection. Data on infection rates and vaccination are limited. A nationwide, cross-sectional study focusing on AGP-related specialties was conducted between 3 May 2021 and 14 June 2021. Vaccination rates among HCW, perception of infection risk, and infection rates were analyzed, focusing on the comparison of gastrointestinal endoscopy (GIE) and other AGP-related specialties (NON-GIE), from the beginning of the pandemic until the time point of the study. Infections rates among HCW developed similarly to the general population during the course of the pandemic, however, with significantly higher infections rates among the GIE specialty. The perceived risk of infection was distributed similarly among HCW in GIE and NON-GIE (91.7%, CI: 88.6−94.4 vs. 85.8%, CI: 82.4−89.0; p < 0.01) with strongest perceived threats posed by AGPs (90.8%) and close patient contact (70.1%). The very high vaccination rate (100−80%) among physicians was reported at 83.5%, being significantly more frequently reported than among nurses (56.4%, p < 0.01). GIE had more often stated very high vaccination rate compared with NON-GIE (76.1% vs. 65.3%, p < 0.01). A significantly higher rate of GIE was reported to have fewer concerns regarding infection risk after vaccination than NON-GIE (92.0% vs. 80.3%, p < 0.01).

Caries Experience and Increment in Children Attending Kindergartens with an Early Childhood Caries Preventive Program Compared to Basic Prophylaxis Measures-A Retrospective Cohort Study.

Dental caries constitutes a public health challenge. As preventive strategies are desirable, this retrospective cohort study aimed to assess the caries experience and increment in children attending kindergartens with an early childhood caries (ECC) preventive program (intervention group, IG) compared to basic prophylaxis measures (control group, CG) located in areas of different socioeconomic status (SES) within Marburg (Germany). The long-term caries experience (2009−2019) of these 3−5-year-old kindergarten children was evaluated. For the caries increment, dental records of 2019 were screened for the availability of a minimum of two dental examinations at least 8 months apart. Caries was scored according to the WHO criteria (dmf−t). The data were split by observation period (300−550 and >550 days). Overall, 135 children (Ø 3.7 years) attended IG, and 132 children (Ø 3.6 years) attended CG. After 300−550 days, no significant differences were found between both groups regarding mean caries increment and experience (p > 0.05). After >550 days, IG with low SES exhibited a high caries experience. Fluoride varnish applications could not reduce the caries increment compared to CG in the short-term but slightly decreased the long-term caries experience. Comprehensive ECC prevention measures actively involving parents are needed to overcome the caries burden.

Active MMP-8 point-of-care (PoC)/chairside enzyme-test as an adjunctive tool for early and real-time diagnosis of peri-implantitis.

OBJECTIVE: The aim of this study was to investigate the utility of the active matrix metalloproteinase (aMMP-8)-point-of-care (PoC) test as a quantitative real-time chair-side diagnostic tool for peri-implant diagnosis, as well as assess the potentially developing and ongoing risk relative to the traditional clinical methods. BACKGROUND: Current peri-implant and periodontal disease diagnoses rely on clinical and radiological examinations. This case-control study investigated the applicability of aMMP-8-PoC immunotest for quantitative real-time diagnosis and monitoring of dental implants in health and disease. METHODS: Sixty-eight patients visiting a specialist clinic for maintenance following dental implant placement underwent assessment of their peri-implant health. aMMP-8-PoC peri-implant sulcular fluid (PISF) lateral-flow immunotests were performed using ImplantSafe® technology quantitated by ORALyzer®. In addition, the PISF samples were analyzed for total MMP-8, calprotectin, and interleukin (IL)-6 by enzyme-linked immunosorbent assays (ELISA), aMMP-8 by western immunoblot, and MMP-2 and MMP-9 by gelatin zymography. RESULTS: The aMMP-8-PoC test promptly recorded and reflected peri-implant disease, differentiating it clearly from health. X-ray findings (bone loss > 2 mm), peri-implant pocket depth ≥ 3 mm, and bleeding on probing were significantly more prevalent among implants positive for the aMMP-8-PoC test. aMMP-8/ORALyzer analysis was more precise in recording disease than total MMP-8, calprotectin, IL-6, MMP-2, and MMP-9. CONCLUSIONS: The aMMP-8-PoC test can be conveniently implemented to alert for and detect active collagenolysis affecting peri-implant tissues, both in the early and advanced stages of the disease. Active and fragmented MMP-8 exhibits a strong and significant association with peri-implantitis as compared to total MMP-8 and other biomarkers and can be utilized as the POC/chairside biomarker of choice in the new classification of peri-implantitis.

Comparison of apical debris extrusion during root canal preparation in primary molars using different file systems: an in vitro study.

This study aimed to compare the amount of debris extrusion of four endodontic systems made of Nickle-Titanium alloy. This in vitro study was done on 80 extracted primary molars. They were selected by cone-beam computed tomography and randomly divided into four groups (n = 20) to be prepared to the apical size of 25 by one of the systems: Reciproc, Protaper Universal, Neolix, or Hyflex CM. Debris was collected into Eppendorf microtubes and placed in an incubator to evaporate the washing solution. Debris was weighed by a digital scale of 0.01 g precision. Data were statistically analysed using SPSS software. Tukey's comparison was used to determine the difference between the four file systems (α = 0.05). Debris extrusion after Reciproc preparation (0.00320) was significantly higher than the other (P < 0.05), with no significant difference having been observed among the other systems (P > 0.05). It can be concluded that all systems under investigation exhibited debris extrusion.

Long-term microtensile bond strength of self-etch adhesives and influence of 7-s phosphoric acid etching on adhesion of a 3-step etch-and-rinse adhesive to the dentine of primary teeth.

BACKGROUND: The immediate microtensile bond strength (µTBS) of self-etch (SE) adhesives to primary dentine is promising, but evidence about the durability is scarce. AIM: To assess the long-term µTBS of SE adhesives to primary dentine and to examine the effect of 7-s etching on µTBS of a 3-step etch-and-rinse (ER) adhesive. DESIGN: The enamel of 115 caries-free human primary teeth was ground flat, and bonding was performed according to group assignment: G-aenial™ Bond/GC [GB], Clearfil™ SE Bond/Kuraray [CS], OptiBond™ XTR/Kerr [OX], Scotchbond™ Universal/3M™ [SU], Prime&Bond® NT™/Dentsply [PB], and OptiBond™ FL/Kerr [OF]. After storage (24 h, 6 mos., 12 mos.), 1,762 beams were cut for µTBS testing. Fracture analysis was performed using light/fluorescence microscopy. Resin-dentine interfaces were exemplarily analyzed using SEM. RESULTS: After 24 h, OX and SU showed significantly higher estimated mean µTBS than GB, which exhibited the lowest µTBS at all stages (p < .05). µTBS within each adhesive group showed slight variations over time (p > .05). OF_SE produced acceptable µTBS. Etching increased the mean immediate µTBS for OF (p > .05) and the percentage of cohesive fractures. CONCLUSIONS: SE adhesives achieved durable µTBS to primary dentine. 7-s etching may improve the immediate µTBS of a 3-step ER adhesive.

Longitudinal craze line propagation in human root dentin after instrumentation with NiTi rotary files of different instrument tapers after long-term chewing simulation.

OBJECTIVES: The aim of this study was to investigate whether file design and taper significantly influence microcrack initiation during machine preparation. MATERIALS AND METHODS: Sixty extracted teeth with straight single canals were selected. The teeth were randomly assigned to four groups based on their root canal anatomy and the corresponding NiTi rotary file system (I, Mtwo; II, ProTaper Universal; III, F6 SkyTaper; control, no preparation and filling). The root canals of the experimental groups were filled using the single-cone technique. The tested teeth were all subjected to a mechanical chewing simulation with flat lead loading over a period of 3 years (corresponding to 150,000 cycles). The teeth were checked for dentinal defects (accumulative crack growth in length) under the digital microscope (Keyence VHX-5000) at time 0 (baseline prior to chewing simulation) and after 3, 6, 12, 24, and 36 months of loading. The cumulative crack increase was statistically analyzed using the Kruskal-Wallis test, Jonckheere-Terpstra test, and the Wilcoxon rank-sum test. The significance was set at p < 0.05. RESULTS: In contrast to preparation with greater-tapered instruments, ProTaper Universal (group II) and F6 SkyTaper (group III) instrumentation with the smaller tapered Mtwo files (group I) showed less accumulative propagation of craze lines (p < 0.05) at all time points. CONCLUSION: Instruments with greater taper for root canal instrumentation should be used with care to avoid negative long-term effects in the form of propagation of dentinal defects over time. A positive cutting-edge angle and a smaller taper have a positive effect on a lower craze line development. CLINICAL RELEVANCE: Instruments with a positive cutting-edge angle and a smaller taper are beneficial for the long-term preservation of dentinal tooth structure.

Wear and marginal quality of aesthetic crowns for primary molars.

BACKGROUND: Due to limited aesthetics of stainless-steel crowns, the demand for tooth-coloured crowns has recently risen. Few studies have investigated the marginal integrity and wear behaviour of tooth-coloured primary molar crowns under subcritical load in vitro. AIM: This in vitro study evaluated the marginal quality and wear of newly introduced resin composite and hybrid ceramic crowns compared with metal and zirconia crowns. DESIGN: Metal, resin composite, hybrid ceramic (CAD/CAM), and various zirconia crowns were investigated. After thermomechanical loading (2,500 thermocycles/100,000 × 50N), marginal quality of luting gaps and wear of crowns/antagonists were evaluated using replicas under a light or 3D laser scanning microscope. Results were analysed with the Mann-Whitney U test or one-way ANOVA (p < .05). RESULTS: Marginal quality of the new resin composite and hybrid ceramic crowns performed well in comparison with SSC and zirconia crowns. Adhesive bonding of crowns resulted in superior marginal seal compared with conventional GIC (Mann-Whitney U test, p < .05). Regarding wear, zirconia crowns exhibited significantly worse results than resin composite or hybrid ceramic crowns and SSCs (ANOVA, p < 0.05). CONCLUSION: The new resin composite and hybrid ceramic crown exhibited good performance in comparison with SSCs and zirconia crowns considering both wear and marginal quality after subcritical loading.