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Journal of Dental Sciences Apr 2022The bond strength and durability of highly translucent zirconia ceramics to dentin is still unclear. The purpose of this study was to investigate the effect of various...
BACKGROUND/PURPOSE
The bond strength and durability of highly translucent zirconia ceramics to dentin is still unclear. The purpose of this study was to investigate the effect of various surface treatments on the bond strength of self-adhesive resin cements to high-translucent zirconia crowns and dentin.
MATERIALS AND METHODS
A high-transparent zirconia and three self-adhesive resin cements (G-CEM LinkAce (GCL), RelyX U200 (RXU) and TotalCem (TTC)) were used. The zirconia surface was sandblasted with 50 μm alumina particles or coated with an SR Link primer, while a dentin primer (Tetric N-Bond Universal, TBU) was applied to the surface of the dentin. By using three self-adhesive resin cements, zirconia samples were bonded to the dentin surfaces of human teeth. The shear strength of the specimens was measured before and after 10,000-cycle thermocycling or 90-day aging.
RESULTS
When using GCL to bond with the untreated dentin and various zirconia surfaces, the shear bond strength of the sandblasted (Z) and RS Link primer-coated (Z) groups was significantly higher than that of the untreated control group (Zc). However, in the case of TBU-treated dentin, the shear strength of the Z + D group was significantly higher than that of the other groups. After thermocycling and aging, the shear strength of the Z + D group using GCL and RXU cements decreased slightly, while the TTC showed no impact.
CONCLUSION
The zirconia surface pretreated by sandblasting and bonding agent, which was sequentially bonded with a primer-treated dentin by using resin cements, can provide excellent shear bond strength and anti-aging performance.
PubMed: 35756805
DOI: 10.1016/j.jds.2021.12.008 -
Journal of Dental Sciences Mar 2021Calcium hydroxide-based materials were the gold standard in vital pulp therapies for decades' despite of several shortcomings. However, calcium silicates have been...
BACKGROUND/PURPOSE
Calcium hydroxide-based materials were the gold standard in vital pulp therapies for decades' despite of several shortcomings. However, calcium silicates have been discussed as an alternative to overcome these drawbacks. It was aimed to investigate the in-vivo effectiveness of different calcium silicates based materials in pulp capping in this study.
MATERIALS AND METHODS
A parallel-design, randomized controlled trial with 213 patients who has deep dentin caries, vital pulps and without spontaneous pain or history of swelling was designed. 525 M teeth were randomized, blinded and allocated to one of the five groups for pulp capping treatment (n = 105). All teeth were followed up clinically and radiographically (after 1st, 6th, 12th and 36th months) by blinded investigators. The clinical and radiographic success, and the effect of the pulp exposure to the success rate analyzed with Wald chi-square and Z tests.
RESULTS
Clinical and radiographic success of MTA+ (86.3%, 85.4%) and Biodentine (79.4%, 80.1%) were found the highest. Although results of Theracal LC group (72.1%, 73.6%) were better than Dycal group (69.4%, 70.2%), the difference was nonsignificant (p > 0.05). Only in light-cured groups, (TheraCal LC & LC Calcihyd) pulpal exposure size effected the success of the materials (p < 0.05). MTA+ and Biodentine resulted better scores, when compared with TheraCal LC in large pulpal exposures (p < 0.05).
CONCLUSION
After 36-month follow-up, both MTA+ and Biodentine were found to be the appropriate material for direct pulp capping in permanent teeth. The filler ingredient of the Theracal-LC eases the usage of calcium silicates but decreases the success rate.
PubMed: 33854725
DOI: 10.1016/j.jds.2020.08.016 -
Polymers Nov 2021The present study aimed to formulate an experimental adhesive (EA) and reinforce it with 5 wt.% titanium dioxide (TiO) or zirconium oxide (ZrO) to yield 5% TiO and 5%...
The present study aimed to formulate an experimental adhesive (EA) and reinforce it with 5 wt.% titanium dioxide (TiO) or zirconium oxide (ZrO) to yield 5% TiO and 5% ZrO adhesives, respectively, and then analyze the impact of this reinforcement on various mechanical properties of the adhesives. The EA contained a blend of monomers such as bisphenol A glycol dimethacrylate (BisGMA), triethylene glycol dimethacrylate (TEGDMA), 2-hydroxyethyl methacrylate (HEMA), and ethyl 4-dimethylamino benzoate and camphorquinone. The EA included ethyl 4-dimethylamino benzoate and camphorquinone photo-initiators, and diphenyliodonium hexafluorophosphate (DPIHP) was also included to act as an electron initiator. The TiO and ZrO nanoparticles were incorporated into the EA post-synthesis. To characterize the filler nanoparticles, scanning electron microscopy (SEM) and line-energy dispersive X-ray (EDX) spectroscopy were performed. The adhesives were characterized by analyzing their rheological properties, shear-bond strength (SBS), and interfacial failure types. Further, the resin-dentin interface was also analyzed via SEM. The TiO nanoparticles were spherically shaped on the SEM micrographs, while the ZrO nanoparticles were seen as non-uniformly shaped agglomerates. The EDX mapping demonstrated the presence of Ti and oxygen for TiO and Zr and oxygen for the ZrO nanoparticles. Both 5% TiO and 5% ZrO adhesives revealed decreased viscosity as compared with the EA. The 5% TiO adhesive demonstrated higher SBS values for both non-thermocycled (NTC) and thermocycled samples (NTC: 25.35 ± 1.53, TC: 23.89 ± 1.95 MPa), followed by the 5% ZrO adhesive group (NTC: 23.10 ± 2.22, TC: 20.72 ± 1.32 MPa). The bulk of the failures (>70%) were of adhesive type in all groups. The SEM analysis of the resin-dentin interface revealed the development of a hybrid layer and resin tags (of variable depth) for the EA and 5% TiO groups. However, for the 5% ZrO group, the hybrid layer and resin tag establishment appeared compromised. Reinforcement of the EA with TiO or ZrO caused an increase in the adhesive's SBS (with the 5% TiO group demonstrating the highest values) in comparison with the EA (without nanoparticles). However, both nanoparticle-containing adhesives revealed decreased viscosity compared with the EA (without nanoparticles). Further studies investigating the impact of diverse filler concentrations on the properties of adhesives are suggested.
PubMed: 34771351
DOI: 10.3390/polym13213794 -
Clinical Oral Investigations Aug 2021Matrix metalloproteases (MMPs) are a family of enzymes that operate a proteolytic activity at the level of the extracellular matrix. MMPs are regulated by tissue...
OBJECTIVES
Matrix metalloproteases (MMPs) are a family of enzymes that operate a proteolytic activity at the level of the extracellular matrix. MMPs are regulated by tissue inhibitors of metalloproteinases (TIMPs) that can ubiquitously bind different enzyme forms. The study aims to identify a morfo-functional association between TIMP-1 and MMP-2 and -9 in human dentin.
MATERIALS AND METHODS
Proteins were extracted from demineralized human sound dentin powder and centrifuged to separate two aliquots with different molecular weights of proteins, higher and lower than 30 kDa. In each aliquot, the evaluation of the presence of TIMP-1/MMP-2 and TIMP-1/MMP-9 was performed using co-immunoprecipitation/immunoblotting analysis. The distribution of TIMP-1, in association with MMP-2 and -9, was investigated using a double immunohistochemical technique. Furthermore, the activity of TIMP-1 was measured by reverse zymography, where acrylamide gel was copolymerized with gelatin and recombinant MMP-2.
RESULTS
Co-immunoprecipitation/immunoblotting analysis showed the association TIMP-1/MMP-2 and TIMP-1/MMP-9 in human sound dentin. Electron microscopy evaluation revealed a diffuse presence of TIMP-1 tightly associated with MMP-2 and -9. Reverse zymography analysis confirmed that TIMP-1 present in human dentin is active and can bind different MMPs isoforms.
CONCLUSIONS
The strict association of TIMP-1 with MMP-2 and -9 in situ appeared a constant finding in the human sound dentin.
CLINICAL RELEVANCE
Considering the role of TIMP-1, MMP-2, and MMP-9 within the connective tissues, clinically applicable protocols could be developed in the future to increase or decrease the level of TIMPs in human dentin to regulate the activity of MMPs, contributing to reduce caries progression and collagen degradation.
Topics: Dentin; Humans; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Matrix Metalloproteinases; Tissue Inhibitor of Metalloproteinase-1; Tissue Inhibitor of Metalloproteinases
PubMed: 33569677
DOI: 10.1007/s00784-021-03819-6 -
International Journal of Biological... 2020Tooth development is a complex process that is regulated precisely by several signalling pathways and transcription factors. GATA-binding protein 4 (GATA4) is a DNA...
Tooth development is a complex process that is regulated precisely by several signalling pathways and transcription factors. GATA-binding protein 4 (GATA4) is a DNA binding transcription factor, and our previous study showed that GATA4 is a novel regulator of root development. However, it remains unclear whether GATA4 is necessary for odontoblast differentiation and dentin formation. Here, we evaluated the phenotypic changes of mice. The mutant mice showed defective dentin and short root deformity. The odontoblasts lost polarity instead of exhibiting a shorter height and flattened morphology. Moreover, the expression of several molecules, such as DSPP, COL-1, DCN, and PCNA, were downregulated during mutant tooth development. , we injected lentivirus to overexpress GATA4 in mice root. The dentin formation and the expression of odonto/osteogenic markers (DSPP, COL-1, DCN) were enhanced in the GATA4 overexpression group. During the study, the ability of proliferation, migration and odonto/osteogenic differentiation was declined by GATA4 knockdown approach in human dental pulp stem cells (DPSCs). The expression of odonto/osteogenic markers (DSPP, BMP4, RUNX2, OSX, OPN, OCN) was reduced in the shGATA4 group, while overexpressing GATA4 in DPSCs promoted mineralization. Furthermore, an immunoprecipitation-mass spectrometry procedure was used to confirm the interaction between GATA4 and Fructose-1, 6-bisphosphatase 1 (FBP1). We used gain and lose-of-function to delineated the role of GATA4 in regulating FBP1 expression. Knocking down GATA4 in DPSCs resulted in decreased glucose consumption and lactate production. We used small hairpin RNA targeting FBP1 to reduce the expression of FBP1 in DPSCs, which significantly increased glucose consumption and lactate production. Together, the results suggested that GATA4 is important for root formation and odontoblast polarity, as it promotes the growth and differentiation of dental mesenchymal cells around the root and affects the glucose metabolism of DPSCs the negative regulation of FBP1.
Topics: Animals; Cell Differentiation; Dentin; Dentinogenesis; Fructose-Bisphosphatase; GATA4 Transcription Factor; Gluconeogenesis; Mice, Knockout; Multipotent Stem Cells; Neural Crest; Odontoblasts; Tooth Root
PubMed: 31892855
DOI: 10.7150/ijbs.36567 -
Journal of Prosthodontic Research Aug 2021Purpose To explore fracture strength and failure behaviour of minimally invasive CAD-CAM composite resin overlay restorations.Methods Eighty bi- and tri-layer...
Purpose To explore fracture strength and failure behaviour of minimally invasive CAD-CAM composite resin overlay restorations.Methods Eighty bi- and tri-layer cylindrical overlay model including the restoration bonded over bovine tooth dentin (Groups D) and enamel-dentin (Groups E) were assembled (diameter 9 mm). Restorations were milled from CAD-CAM composite resin blocks (Brilliant Crios, Coltène/Whaledent AG) in different thicknesses (0.5mm, 1mm, 1.5mm, 2mm) and equally distributed in four Groups D and four Groups E (n=10). All specimens were submitted to an Hertzian load-to-failure contact test with spherical indenter. Critical loads were recorded in Newton and data were analysed using Kruskal-Wallis test for multiple and Mann-Whitney test for 2-samples comparisons (p < 0.05). Fragments were examined using SEM. The stress distribution for specimens with restorations of 0.5 mm and 2 mm was also investigated with FEA.Results For all specimens, the mean static loads in Newton increased with an increase in restoration thickness. On contrary, restorations with the same thickness displayed higher resistance values when bonded over enamel than dentin, except for the 2-mm thick restorations. A damage competition was detected between cone/median cracks originating at the loading contact area of the restorations and radial cracks beginning at their inner surface, with the former prevailing in restorations bonded on enamel and the latter being dominant for restorations bonded on dentin.Conclusions For bonded ultra-thin resin composite restorations (0.5 mm to 1.5 mm) enamel as bonding substrate assures higher critical loads to fracture than dentin. This influence gradually decreases as restoration thickened.
Topics: Animals; Cattle; Composite Resins; Dental Bonding; Dental Cements; Dental Porcelain; Dental Stress Analysis; Dentin; Materials Testing; Resin Cements; Surface Properties
PubMed: 33762503
DOI: 10.2186/jpr.JPR_D_20_00008 -
Clinical Oral Investigations Jan 2022To assess tooth discoloration induced by different hydraulic calcium silicate-based cements (HCSCs), including effects of blood and placement method.
OBJECTIVES
To assess tooth discoloration induced by different hydraulic calcium silicate-based cements (HCSCs), including effects of blood and placement method.
MATERIALS AND METHODS
Eighty bovine teeth cut to a length of 18 mm (crown 8 mm, root 10 mm) were randomly assigned to 10 groups (n = 8), receiving orthograde apical plug treatment (APT). Apical plugs were 4 mm in length and made of ProRoot MTA (Dentsply), Medcem MTA (Medcem), TotalFill BC RRM Fast Set Putty (Brasseler), or Medcem Medical Portland Cement (Medcem) plus bismuth oxide (Bi2O3) with and without bovine blood. Further, orthograde (with or without preoperative adhesive coronal dentin sealing) and retrograde APT were compared. Teeth were obturated with gutta-percha and sealer, sealed with composite and stored in distilled water. Tooth color was measured on apical plug, gutta-percha/sealer, and crown surface before treatment versus 24 h, 1, 3, 6, 12, and 24 months after treatment by spectrophotometry. Color difference (ΔE) values were calculated and analyzed by Shapiro-Wilk test, ANOVA with post hoc tests, Friedman test, t test, and post hoc tests with Bonferroni correction (α = .05).
RESULTS
Tooth discoloration occurred in all groups with no significant differences between HCSCs (p > .05). After 24 months, color changes were prominent on roots but insignificant on crowns. Blood contamination induced a significantly decreased luminescence (p < .05). Blood had a stronger impact on tooth color than BiO. No relevant effects of retrograde placement (p > .05) or preoperative dentin sealing (p > .05) were detected.
CONCLUSIONS
Apical plugs of the tested HCSCs cause discoloration of bovine roots, but not discoloration of bovine tooth crowns within a 24-month period.
CLINICAL RELEVANCE
APT should be performed carefully while avoiding direct contact with the coronal dentin, and in that case no aesthetic impairments occur.
Topics: Animals; Calcium Compounds; Cattle; Drug Combinations; Root Canal Filling Materials; Silicates; Tooth Discoloration
PubMed: 34151389
DOI: 10.1007/s00784-021-04009-0 -
Clinical Oral Investigations Jan 2023For a conventional indirect restoration, temporary cementation inevitably contaminated collapsed dentin collagen. The purpose of this review was to evaluate the optimal... (Meta-Analysis)
Meta-Analysis Review
OBJECTIVES
For a conventional indirect restoration, temporary cementation inevitably contaminated collapsed dentin collagen. The purpose of this review was to evaluate the optimal strategy for minimizing its negative effects.
MATERIAL AND METHODS
Databases such as PubMed, Web of Science, EMBASE, and the Cochrane Library were searched for in vitro studies, involving the influence of immediate dentin sealing (IDS), different temporary cements, and their removal strategies on dentin bond strength. The meta-analysis used the inverse variance method with effect method of the standardized mean difference and statistical significance at p ≤ 0.05. The I value and the Q-test were used to assess the heterogeneity.
RESULTS
A total of 14 in vitro trials were subjected to the meta-analysis. Within the study's limitations, we assumed that IDS eliminated the negative effects of temporary bonding, achieving the comparable immediate bond strength with the control (p = 0.46). In contrast, under delayed dentin sealing (DDS), temporary cementation statistically decreased bond strength (p = 0.002). Compared with resin-based and non-eugenol zinc oxide cements, polycarboxylate and calcium hydroxide cements performed better on bond strength with no statistical difference from the control group (p > 0.05). Among the removal methods of temporary cements, the AlO abrasion restored the decreased bond strength (p = 0.07) and performed better than hand instruments alone (p = 0.04), while pumice removal slightly reduced the bond strength in contrast with the control group (p = 0.05, 95% CI = - 1.62 to 0).
CONCLUSIONS
The choices of IDS, polycarboxylate and calcium hydroxide temporary cements, AlO abrasion removal method were feasible and efficient to enhance the bond strength.
CLINICAL RELEVANCE
It is worthwhile applying IDS technique, polycarboxylate and calcium hydroxide temporary cements during indirect restoration. The AlO abrasion of cleaning dentin can minimize the negative effects of temporary cement.
Topics: Resin Cements; Dental Bonding; Dentin-Bonding Agents; Calcium Hydroxide; Dental Cements; Materials Testing; Dentin; Tensile Strength; Dental Stress Analysis
PubMed: 36422719
DOI: 10.1007/s00784-022-04790-6 -
Journal of Dentistry Apr 2022The biomechanical response of an autotransplanted tooth and surrounding bone to occlusal loads is not well-known. The aim of the present study was to investigate the...
OBJECTIVE
The biomechanical response of an autotransplanted tooth and surrounding bone to occlusal loads is not well-known. The aim of the present study was to investigate the effect of root form and occlusal morphology on stress distribution in autotransplanted teeth and surrounding bone by using finite element analysis (FEA).
METHODS
Seven FEA models representing different autotransplanted tooth situations were generated: (a) first molar, (b) third molar, (c) root canal-treated third molar, (d) root canal-treated, ankylosed, third molar, (e) crowned third molar, (f) crowned and root canal-treated third molar, (g) root canal-treated, ankylosed, and crowned third molar. Load (200 N) was applied on the occlusal surface, parallel to the long axis of the tooth. Maximum von Mises stress values on dentin and surrounding bone were calculated for each situation.
RESULTS
Differences in stress distribution were observed among models. In ankylosed model, stress was primarily observed at the coronal region of the tooth. The stress was observed more at the coronal region of the tooth in crowned models compared with the non-crowned models. The stress distribution was homogeneous with root canal-treated and crowned autotransplanted tooth.
CONCLUSIONS
The occlusal morphology and root form of the autotransplanted tooth affected the stress in surrounding bone at the transfer site and the biomechanical response of the tooth. The stress was more homogeneous in crowned tooth and primarily observed at the coronal region, which may decrease the risk for root resorption.
CLINICAL SIGNIFICANCE
Root configuration, occlusal form and root canal treatment induce significant changes on the stress distribution on teeth and bone, including characteristic stress concentration and increased stress values. Clinicians can consider crowning autotransplanted teeth for improved stress distribution within the tooth structure.
Topics: Finite Element Analysis; Humans; Molar; Molar, Third; Stress, Mechanical; Tooth, Nonvital
PubMed: 35247471
DOI: 10.1016/j.jdent.2022.104082 -
Journal of Bioactive and Compatible... May 2022Grape seed extract contains a complex mixture of proanthocyanidins (PACs), a plant biopolymer used as a biomaterial to improve reparative and preventive dental...
AIM
Grape seed extract contains a complex mixture of proanthocyanidins (PACs), a plant biopolymer used as a biomaterial to improve reparative and preventive dental therapies. Co-polymerization of PACs with type I collagen mechanically reinforces the dentin extracellular matrix. This study assessed the biocompatibility of PACs from grape seed extract on dental pulp stem cells (DPSCs) in a model simulating leaching through dentin to the pulp cavity. The aim was to determine the type of PACs (galloylated vs. non-galloylated) within grape seed extract that are most compatible with dental pulp tissue.
METHODOLOGY
Human demineralized dentin was treated with selectively-enriched dimeric PACs prepared from grape seed extract using liquid-liquid chromatography. DPSCs were cultured within a 2D matrix and exposed to PAC-treated dentin extracellular matrix. Cell proliferation was measured using the MTS assay and expression of odontoblastic genes was analyzed by qRT-PCR. Categorization of PACs leaching from dentin was performed using HPLC-MS.
RESULTS
Enriched dimeric fractions containing galloylated PACs increased the expression of certain odontoblastic genes in DPSCs, including Runt-related transcription factor 2 (RUNX2), vascular endothelial growth factor (VEGF), bone morphogenetic protein 2 (BMP2), basic fibroblast growth factor (FGF2), dentin sialophosphoprotein (DSPP) and collagen, type I, alpha 1 (COLI). Galloylated dimeric PACs also exhibited minor effects on DPSC proliferation, resulting in a decrease compared to control after five days of treatment. The non-galloylated dimer fraction had no effect on these genes or on DPSC proliferation.
CONCLUSIONS
Galloylated PACs are biocompatible with DPSCs and may exert a beneficial effect on cells within dental pulp tissue. The observed increase in odontoblastic genes induced by galloylated PACs together with a decrease in DPSC proliferation is suggestive of a shift toward cell differentiation. This data supports the use of dimeric PACs as a safe biomaterial, with galloylated dimeric PACs exhibiting potential benefits to odontoblasts supporting dentin regeneration.
PubMed: 37465414
DOI: 10.1177/08839115221095154