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1.
Adv Mater ; : e1907833, 2020 Apr 09.
Artigo em Inglês | MEDLINE | ID: mdl-32270552

RESUMO

Microbe-mediated mineralization is ubiquitous in nature, involving bacteria, fungi, viruses, and algae. These mineralization processes comprise calcification, silicification, and iron mineralization. The mechanisms for mineral formation include extracellular and intracellular biomineralization. The mineral precipitating capability of microbes is often harnessed for green synthesis of metal nanoparticles, which are relatively less toxic compared with those synthesized through physical or chemical methods. Microbe-mediated mineralization has important applications ranging from pollutant removal and nonreactive carriers, to other industrial and biomedical applications. Herein, the different types of microbe-mediated biomineralization that occur in nature, their mechanisms, as well as their applications are elucidated to create a backdrop for future research.

2.
Artigo em Inglês | MEDLINE | ID: mdl-32207559

RESUMO

In the progression of osteoarthritis, pathological calcification in the affected joint is an important feature. The role of these crystallites in the pathogenesis and progression of osteoarthritis is controversial; it remains unclear whether they act as a disease initiator or are present as a result of joint damage. Recent studies reported that the molecular mechanisms regulating physiological calcification of skeletal tissues are similar to those regulating pathological or ectopic calcification of soft tissues. Pathological calcification takes place when the equilibrium is disrupted. Calcium phosphate crystallites are identified in most affected joints and the presence of these crystallites is closely correlated with the extent of joint destruction. These observations suggest that pathological calcification is most likely to be a disease initiator instead of an outcome of osteoarthritis progression. Inhibiting pathological crystallite deposition within joint tissues therefore represents a potential therapeutic target in the management of osteoarthritis.

3.
J Dent ; 94: 103297, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32057768

RESUMO

OBJECTIVES: The role played by macrophages in regulating the differentiation of mesenchymal stem cells (MSCs) during wound healing and bone regeneration is increasingly being recognized. The present study compared the pro-osteogenic effects of three co-culture methods, conditioned medium generated by macrophages (CM), indirect culture (IC) or direct culture (DC) with macrophages, on bone marrow MSCs (BMMSCs). METHODS: Primary BMMSCs were isolated, characterized and co-cultured with RAW264.7 mouse macrophages. Cell morphology and intracellular reactive oxygen species (ROS) levels were determined by scanning electron microscopy (SEM) and flow cytometry, respectively. Alkaline phosphatase (ALP) staining and assay, Alizarin red staining (ARS) and quantitative real-time polymerase chain reaction (qRT-PCR) were performed to evaluate osteogenic differentiation. RESULTS: Inclusion of macrophages in any of the three co-culture methods resulted in improvement in osteogenic differentiation and mineralization of BMMSCs (DC > IC > CM), as measured by ALP staining and activity, ARS and osteoblastic gene expression (Runx2, Alp, Ocn and Bmp2). The enhanced osteogenesis was reversed with hydrogen peroxide. Macrophages reduced the increased levels of intracellular ROS generated by BMMSCs during osteogenic differentiation in a manner similar to the use of an antioxidant, N-acetyl cysteine. CONCLUSIONS: Macrophages exert an osteogenesis-enhancing effect to accelerate BMMSC osteogenesis via ROS downregulation. CLINICAL SIGNIFICANCE: The present findings suggest that targeting MSC-macrophage interaction is an effective strategy for regulating stem cell fate and facilitating bone regeneration.

4.
Bone ; 133: 115229, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31926929

RESUMO

ß2-adrenergic signal transduction in mesenchymal stem cells (MSCs) induces subchondral bone loss in osteoarthritis (OA) of temporomandibular joints (TMJs). However, whether conditional deletion of ß2-adrenergic receptor (Adrb2) in nestin+ MSCs can alleviate TMJ-OA development remains unknown. In this study, nestin-Cre mice were crossed with Adrb2 flox mice to generate mice lacking Adrb2 expression specifically in the nestin+ MSCs (Adrb2-/-), and TMJ-OA development in such mice was investigated. Adrb2 flox mice (Adrb2+/+) and Adrb2-/- mice were subjected to unilateral anterior crossbite (UAC), while mice in the control group were subjected to sham operation. Adrb2+/+ and Adrb2-/- mice in the control group showed no distinguishable phenotypic changes in body weight and length, mandibular condylar size, and other histomorphological parameters of the condylar subchondral bone. A significant increase in subchondral bone loss and cartilage degradation was observed in Adrb2+/+ UAC mice; the former was characterized by decreased bone mineral density, bone volume fraction, and trabecular plate thickness, and increased trabecular separation, osteoclast number and osteoclast surface, and pro-osteoclastic factor expression; the latter was characterized by decreased cartilage thickness, chondrocyte density, proteoglycan area, and collagen II and aggrecan expression, but increased matrix metalloproteinase and alkaline phosphatase expression and percentage area of calcified cartilage. Adrb2 deletion in nestin+ MSCs largely attenuated UAC-induced increase in condylar subchondral bone loss, cartilage degradation, and aberrant calcification at the osteochondral interface. Thus, Adrb2-expressing MSCs in the condylar subchondral bone play an important role in TMJ-OA progression and may serve as novel therapeutic targets for TMJ-OA.

5.
Acta Biomater ; 101: 69-101, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31542502

RESUMO

Failure of dental treatments is mainly due to the biofilm accumulated on the dental materials. Many investigations have been conducted on the advancements of antimicrobial dental materials. Polymeric and inorganic nanoscopical agents are capable of inhibiting microorganism proliferation. Applying them as fillers in dental materials can achieve enhanced microbicidal ability. The present review provides a broad overview on the state-of-the-art research in the field of antimicrobial fillers which have been adopted for incorporation into dental materials over the last 5 years. The antibacterial agents and applications are described, with the aim of providing information for future investigations. STATEMENT OF SIGNIFICANCE: Microbial infection is the primary cause of dental treatment failure. The present review provides an overview on the state-of-art in the field of antimicrobial nanoscopical or polymeric fillers that have been applied in dental materials. Trends in the biotechnological development of these antimicrobial fillers over the last 5 years are reviewed to provide a backdrop for further advancement in this field of research.

6.
J Dent ; 91: 103231, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31712128

RESUMO

OBJECTIVES: To compare the anti-biofilm efficacy of two antimicrobial peptides (AMPs), 1018 and DJK-5, in disrupting canal wall biofilms in the isthmus, canal and dentinal tubules of single-rooted maxillary premolars. METHODS: Enterococcus faecalis single-species biofilms were formed in-situ in the root canal system of the premolars (n = 91). Confocal laser scanning microscopy, bacterial sampling, colony-forming unit counting, XTT assay, lactate dehydrogenase assay and phenol-sulphuric acid method were used to identify the anti-biofilm efficacy of both AMPs and their influence on bacterial metabolic activity. RESULTS: Both AMPs disrupted in-situ E. faecalis biofilms and altered their metabolic activity. At 20 µg/mL, the d-enantiomeric AMP DJK-5 killed 55.5 %, 57.3 % and 55.8 % of biofilm bacteria in the isthmus, canal and dentinal tubules, respectively, in 1 min. In contrast, the l-enantiomeric AMP 1018 only eradicated 25.6 %, 25.5 % and 27.5 % of biofilm bacteria in the isthmus, canal and dentinal tubules, respectively, within the same time. Anti-biofilm efficacy of the root canal irrigants tested were in the order: 6 % NaOCl > 20 µg/mL DJK-5 > 10 µg/mL DJK-5 > 20 µg/mL 1018 > 10 µg/mL 1018 > 0.9 % NaCl. CONCLUSIONS: The present results are confirmatory of previous studies, in that d-enantiomeric AMPs exhibit more potent antibacterial properties than l-enantiomeric AMPs against E. faecalis biofilms within the canal space. Nevertheless, the potency of both AMPs are concentration-dependent. Incorporation of these agents into EDTA, a non-antibacterial calcium-chelating irrigant for removal of the inorganic component of the canal space debris, does not reduce the efficacy of either AMP. CLINICAL SIGNIFICANCE: The present study provides the proof of concept that incorporation of an antimicrobial peptide into a calcium-chelating root canal irrigant enhances the disinfection of intratubular single-species biofilms during smear layer and smear plug removal.

7.
Int J Oral Sci ; 11(3): 28, 2019 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-31570700

RESUMO

Effective control of oral biofilm infectious diseases represents a major global challenge. Microorganisms in biofilms exhibit increased drug tolerance compared with planktonic cells. The present review covers innovative antimicrobial strategies for controlling oral biofilm-related infections published predominantly over the past 5 years. Antimicrobial dental materials based on antimicrobial agent release, contact-killing and multi-functional strategies have been designed and synthesized for the prevention of initial bacterial attachment and subsequent biofilm formation on the tooth and material surface. Among the therapeutic approaches for managing biofilms in clinical practice, antimicrobial photodynamic therapy has emerged as an alternative to antimicrobial regimes and mechanical removal of biofilms, and cold atmospheric plasma shows significant advantages over conventional antimicrobial approaches. Nevertheless, more preclinical studies and appropriately designed and well-structured multi-center clinical trials are critically needed to obtain reliable comparative data. The acquired information will be helpful in identifying the most effective antibacterial solutions and the most optimal circumstances to utilize these strategies.


Assuntos
Antibacterianos/farmacologia , Infecções Bacterianas/tratamento farmacológico , Biofilmes/efeitos dos fármacos , Boca/microbiologia , Antibacterianos/uso terapêutico , Anti-Infecciosos/farmacologia , Anti-Infecciosos/uso terapêutico , Humanos , Plâncton
8.
Acta Biomater ; 96: 35-54, 2019 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-31146033

RESUMO

Over 2500 articles and 200 reviews have been published on the bioactive tri/dicalcium silicate dental materials. The indications have expanded since their introduction in the 1990s from endodontic restorative and pulpal treatments to endodontic sealing and obturation. Bioactive ceramics, based on tri/dicalcium silicate cements, are now an indispensable part of the contemporary dental armamentarium for specialists including endodontists, pediatric dentists, oral surgeons andfor general dentists. This review emphasizes research on how these materials have conformed to international standards for dental materials ranging from biocompatibility (ISO 7405) to conformance as root canal sealers (ISO 6876). Potential future developments of alternative hydraulic materials were included. This review provides accurate materials science information on these important materials. STATEMENT OF SIGNIFICANCE: The broadening indications and the proliferation of tri/dicalcium silicate-based products make this relatively new dental material important for all dentists and biomaterials scientists. Presenting the variations in compositions, properties, indications and clinical performance enable clinicians to choose the material most suitable for their cases. Researchers may expand their bioactive investigations to further validate and improve materials and outcomes.

9.
Acta Biomater ; 90: 424-440, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-30953801

RESUMO

During development of mineralized collagenous tissues, intrafibrillar mineralization is achieved by preventing mineralization precursor inhibitors that are larger than 40 kDa from entering the collagen fibrils. Such a property is incorporated in the design of a calcium chelator for dentin bonding in the etch-and-rinse technique that selectively demineralizes extrafibrillar apatite while leaving the intrafibrillar minerals intact. This strategy prevents complete demineralization of collagen fibrils, avoids collapse of collagen that blocks resin infiltration after air-drying, and protects the completely demineralized fibrils from bacteria colonization and degradation by endogenous proteases after resin bonding. In the present study, a water-soluble glycol chitosan-EDTA (GCE) conditioner was synthesized by conjugation of EDTA, an effective calcium chelator, to high molecular weight glycol chitosan, which exhibits weak chelation property. The GCE conjugate was purified, characterized by FTIR, 1H NMR, isothermal titration calorimetry and ICP-AES, and subjected to size exclusion dialysis to recover molecules that are >40 kDa. The optimal concentration and application time for etching dentin were determined by bond strength testing to ensure that the dentin bonding results were comparable to phosphoric acid etching, and maintained equivalent bond strength after air-drying of the conditioned collagen matrix. Extrafibrillar demineralization was validated with transmission electron microscopy. Inhibition of endogenous dentin proteases was confirmed using in-situ zymography. The water-soluble GCE dentin conditioner was non-cytotoxic and possessed antibacterial activities against planktonic and single-species biofilms, supporting its ongoing development as a dentin conditioner with air-drying, anti-proteolytic and antibacterial properties to enhance the durability of bonds created using the etch-and-rinse bonding technique. STATEMENT OF SIGNIFICANCE: The current state-of-the-art techniques for filling decayed teeth with plastic tooth-colored materials require conditioning the mineralized, biofilm-covered, decayed dentin with acids or acid resin monomers to create a surface layer of completely- or partially-demineralized collagen matrix for the infiltration of adhesive resin monomers. Nevertheless, fillings prepared using these strategies are not as durable as consumers have anticipated. Conjugation of polymeric glycol chitosan with EDTA produces a new conditioner for dentin bonding that demineralizes only extrafibrillar dentin, reduces endogenous protease activities and kills biofilm bacteria. The high molecular weight glycol chitosan-EDTA is non-cytotoxic to the key regenerative players within the dentin-pulp complex. This advance permits dry bonding and the use of hydrophobic resins.

10.
J Endod ; 45(5): 651-659, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30833094

RESUMO

The purpose of this study was to report the clinical efficacy of decompression for 3 cases with large periapical lesions and to review technique details. Three cases with large periapical cystic lesions were treated with decompression after root canal treatment. A traditional decompression technique was used for the first case. After aspiration, mucogingival incision, irrigation, and incisional biopsy, a pediatric endotracheal tube was sutured in place and kept for 3 weeks for lesion debridement. An aspiration/irrigation technique was adopted for the second case. An 18-G needle with a syringe was used to aspirate the cystic lesion. Two needles were then inserted into the lesion; copious saline irrigation was delivered from 1 needle and until clear saline was expressed from the other. For the third case, decompression was accomplished with a surgical catheter that was subsequently replaced with a gutta-percha plug after 1 month. None of the 3 cases underwent complete enucleation and root-end surgery. Healed lesions or lesions in healing were observed after 1 to 2 years. Based on the presented cases and published case reports on decompression, a literature review was provided covering indications, technique details, modification, and prognosis of decompression in endodontics. For large periapical cystic lesions, conservative decompression may be used for certain cases before or in lieu of apical surgery. Decompression enables healing of large, persistent periapical lesions after root canal treatment.


Assuntos
Cisto Radicular , Tratamento do Canal Radicular , Criança , Guta-Percha , Humanos , Prognóstico , Cisto Radicular/terapia , Resultado do Tratamento
11.
Acta Biomater ; 85: 229-240, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30593887

RESUMO

Hollow mesoporous silica (HMS) have been extensively investigated as a biomaterial for drug delivery. The present study developed quaternary ammonium silane-grafted hollow mesoporous silica (QHMS) to create a metronidazole (MDZ) sustained delivery system, MDZ@QHMS, with bimodal, contact-kill and release-kill capability. The QHMS was assembled through a self-templating method. Metronidazole was incorporated within the QHMS core using solvent evaporation. Antibacterial activities of the MDZ@QHMS were investigated using single-species biofilms of Staphylococcus aureus (ATCC25923), Escherichia coli (ATCC25922) and Porphyromonas gingivalis (ATCC33277). The MDZ@QHMS maintained a hollow mesoporous structure and demonstrated sustained drug release and bacteridal actvity against the three bacterial strains at a concentration of 100 µg/mL or above. These nanoparticles were not relatively cytotoxic to human gingival fibroblasts when employed below 100 µg/mL. Compared with HMS, the MDZ@QHMS system at the same concentration demonstrated antibiotic-elution and contact-killing bimodal antibacterial activities. The synthesized drug carrier with sustained, bimodal antibacterial function and minimal cytotoxicity possesses potential for localized antibiotic applications. STATEMENT OF SIGNIFICANCE: The present study develops quaternary ammonium silane-grafted hollow mesoporous silica (QHMS) to create a metronidazole (MDZ) sustained delivery system, MDZ@QHMS, with bimodal, contact-kill and release-kill capability. This system demonstrates sustained drug release and maintained a hollow mesoporous structure. The synthesized drug carrier with sustained, bimodal antibacterial function and excellent biocompatibility possesses potential for localized antibiotic applications.


Assuntos
Antibacterianos/farmacologia , Compostos de Amônio Quaternário/farmacologia , Silanos/química , Dióxido de Silício/química , Bactérias/efeitos dos fármacos , Morte Celular/efeitos dos fármacos , Liberação Controlada de Fármacos , Humanos , Metronidazol/farmacologia , Testes de Sensibilidade Microbiana , Viabilidade Microbiana/efeitos dos fármacos , Porosidade , Difração de Raios X
12.
Adv Sci (Weinh) ; 5(10): 1800873, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30356983

RESUMO

Biomineralization in vertebrates is initiated via amorphous calcium phosphate (ACP) precursors. These precursors infiltrate the extracellular collagen matrix where they undergo phase transformation into intrafibrillar carbonated apatite. Although it is well established that ACP precursors are released from intracellular vesicles through exocytosis, an unsolved enigma in this cell-mediated mineralization process is how ACP precursors, initially produced in the mitochondria, are translocated to the intracellular vesicles. The present study proposes that mitophagy provides the mechanism for transfer of ACP precursors from the dysfunctioned mitochondria to autophagosomes, which, upon fusion with lysosomes, become autolysosomes where the mitochondrial ACP precursors coalesce to form larger intravesicular granules, prior to their release into the extracellular matrix. Apart from endowing the mitochondria with the function of ACP delivery through mitophagy, the present results indicate that mitophagy, triggered upon intramitochondrial ACP accumulation in osteogenic lineage-committed mesenchymal stem cells, participates in the biomineralization process through the BMP/Smad signaling pathway.

13.
J Dent ; 79: 68-76, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30296552

RESUMO

OBJECTIVE: To investigate the anti-biofilm efficacy of root canal irrigants in canal spaces, isthmi and dentinal tubules of root canals ex vivo. METHODS: Fifty-one single-rooted premolars, each containing an isthmus, were instrumented, autoclaved and inoculated with Enterococcus faecalis for 4 weeks. One specimen was sectioned for bacteria-specific staining to confirm the presence of biofilms using light microscopiy. The remaining specimens were randomly divided to five groups: (1) 0.9% NaCl, (2) SilverSol/H2O2, (3) HYBENX, (4) QMix 2 in1, (5) 6% NaOCl. Bacterial sampling was performed before (S1) and after (S2) canal irrigation. Diluted bacteria suspension was cultured for 48 h for counting the colony forming units (CFU). Percentages of dead bacteria and biofilm thickness were evaluated by confocal laser scanning microscopy (CLSM). Metabolic activity, lactic acid and polysaccharide synthesis of E. faecalis derived from S2 samples were analysed. RESULTS: The percentages of dead bacteria were significantly affected by the factor "irrigant" (p < 0.001) and the factor "location" (p = 0.017). The percentages of dead bacteria in the isthmi and canals were both in the ordor: NaCl < SilverSol/H2O2 < HYBENX < QMix 2 in1 < NaOCl (p < 0.05). Only 6% NaOCl disrupted biofilms and significantly reduced their thickness. The CFU, metabolic activity, polysaccharide and lactic acid production of E. faecalis were all reduced by the disinfecting solutions. CONCLUSIONS: SilverSol/H2O2 and HYBENX were less adept than QMix 2 in1 at killing biofilm bacteria in root canals. None of these antibacterial irrigants were effective, compared with 6% NaOCl, in disrupting biofilms. CLINICAL SIGNIFICANCE: There is advantage in using HYBENX or QMix 2 in1 to kill intratubular bacteria biofilms because of their capability in removing the inorganic component of the smear layer. SilverSol/H2O2 requires extra time to eradicate intratubular biofilms upon removal of the organic and inorganic components of the smear layer by other root canal irrigants.


Assuntos
Enterococcus faecalis , Irrigantes do Canal Radicular , Biofilmes , Cavidade Pulpar , Peróxido de Hidrogênio , Hipoclorito de Sódio
14.
Dent Mater ; 34(12): 1814-1827, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30342771

RESUMO

OBJECTIVE: Secondary caries and degradation of hybrid layers are two major challenges in achieving durable resin-dentin bonds. The objectives of the present study were to investigate the effects of a 2% quaternary ammonium silane (QAS) cavity cleanser on bacteria impregnated into dentin blocks and the gelatinolytic activity of the hybrid layers. METHODS: Microtensile bond strength was first performed to evaluate if the 2% QAS cavity cleanser adversely affected bond strength. For antibacterial testing, Streptococcus mutans and Actinomyces naeslundii were impregnated into dentin blocks, respectively, prior to the application of the cavity cleanser. Live/dead bacterial staining and colony-forming unit (CFU) counts were performed to evaluate their antibacterial effects. Gelatinolytic activity within the hybrid layers was directly examined using in-situ zymography. A double-fluorescence technique was used to examine interfacial permeability immediately after bonding. RESULTS: The cavity cleanser did not adversely affect the bond strength of the adhesives tested (p>0.05). Antibacterial testing indicated that 2% QAS significantly killed impregnated bacteria within the dentin blocks compared with control group (p<0.05), which was comparable with the antibacterial activity of 2% chlorhexidine (p>0.05). Hybrid layers pretreated with 2% QAS showed significant decrease in enzyme activity compared with control group. With the use of 2% QAS, relatively lower interfacial permeability was observed, compared with control group and 2% chlorhexidine (p<0.05). SIGNIFICANCE: The present study developed a 2% QAS cavity cleanser that possesses combined antimicrobial and anti-proteolytic activities to extend the longevity of resin-dentin bonds.


Assuntos
Antibacterianos/farmacologia , Desinfetantes/farmacologia , Inibidores de Proteases/farmacologia , Compostos de Amônio Quaternário/farmacologia , Silanos/farmacologia , Actinomyces/efeitos dos fármacos , Antibacterianos/química , Colagem Dentária , Materiais Dentários/química , Materiais Dentários/farmacologia , Dentina/enzimologia , Adesivos Dentinários/química , Adesivos Dentinários/farmacologia , Desinfetantes/química , Humanos , Técnicas In Vitro , Teste de Materiais , Inibidores de Proteases/química , Compostos de Amônio Quaternário/química , Células-Tronco , Streptococcus mutans/efeitos dos fármacos , Resistência à Tração
15.
J Dent ; 78: 46-50, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30077808

RESUMO

INTRODUCTION: The present study examined the effects of irrigant flow rate and simulated intraosseous sinusoidal pressure on the rate of NaOCl extrusion from the apical terminus of a faux root canal. METHODS: An extrusion setup was designed to enable irrigant extrusion to be opposed by 30 mm Hg simulated intraosseous pressure. The faux canal apex was opposed by atmospheric + 30 mm Hg pressure (experimental) or atmospheric pressure only (control group). Using five irrigant delivery rates (15.6 8.0, 4.0, 3.4 or 3.0 mL/min), the extrusion rates of 2% NaOCl from the faux apex were measured in both groups (n = 16). Data were analysed with two-factor ANOVA and pairwise comparisons at α = 0.05. Correlation between NaOCl delivery rates and extrusion rates in both groups were analysed with the Pearson product-moment procedure. RESULT: Irrespective of the presence or absence of simulated sinusoidal pressure, NaOCl extrusion rates were positively-correlated with irrigant flow rates. For the factor "irrigant flow rates", significant differences in NaOCl extrusion rates were identified among all flow rates (p < 0.05), except for the pairwise comparison between 4.0 and 3.4 mL/min in the control. For all irrigant flow rates, NaOCl extrusion rate was significantly lower in the presence of 30 mm Hg simulated sinusoidal pressure than that obtained in the absence of opposing pressure (p < 0.05). CONCLUSION: In the presence of 30 mm Hg simulated intraosseous pressure, NaOCl delivered via a side-vented needle inserted to 1 mm short of working length may be prevented from extrusion when its flow rate is ≤ 3.0 mL/min. CLINICAL SIGNIFICANCE: When opposed by intraosseous sinusoidal pressure, NaOCl delivered via a side-vented needle inserted to 1 mm short of working length may be prevented from extrusion when its flow rate is ≤ 3.0 mL/min.


Assuntos
Pressão , Irrigantes do Canal Radicular , Preparo de Canal Radicular , Hipoclorito de Sódio , Irrigação Terapêutica , Humanos , Agulhas , Irrigantes do Canal Radicular/uso terapêutico , Preparo de Canal Radicular/métodos , Hipoclorito de Sódio/uso terapêutico
16.
Acta Biomater ; 75: 171-182, 2018 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-29883811

RESUMO

Secondary caries and hybrid layer degradation are two major challenges encountered in long-term resin-dentin bond stability. As a link between resin and dentin, adhesives that possess both antimicrobial and anti-proteolytic activities are in demand for eliminating bacteria-induced secondary caries and preventing hybrid layers from degradation. In the present study, a new quaternary ammonium methacryloxy silane (QAMS) prepared from sol-gel chemistry was incorporated into experimental adhesives to examine their antimicrobial effect and anti-proteolytic potential. This functional methacrylate resin monomer contains polymerizable methacryloxy functionalities as well as a positively-charged quaternary ammonium functionality with a long, lipophilic -C18H37 alkyl chain for puncturing the cell wall/membrane of surface-colonizing organisms. Antibacterial testing performed using agar diffusion test, live/dead bacterial staining and colony-forming unit counts all indicated that the QAMS-containing adhesives killed Streptococcus mutans and Actinomyces naeslundii in a dose-dependent manner via a predominant contact-killing mechanism. Gelatinolytic activity within the hybrid layers created by these adhesives was examined using in-situ zymography. Hybrid layers created with 0% QAMS-containing adhesive exhibited intense green fluorescence emitted by the hydrolyzed fluorescein-conjugated gelatin, with 4-fold increase in enzymatic activity compared with an experimental adhesive containing 5% QAMS. Taken together, incorporation of 5% QAMS in the experimental adhesive provides simultaneous antimicrobial and anti-proteolytic activities that are crucial for the maintenance of long-term resin-dentin bond integrity. STATEMENT OF SIGNIFICANCE: Durability of resin-dentin interfacial bond remains a clinically-significant challenge. Secondary caries caused by bacteria and the degradation of hybrid layers via endogenous dentin proteases are two important contributors to the poor resin-dentin bond durability. The present study developed a new 5% QAMS-containing adhesive that provides simultaneous antimicrobial and dentin protease inhibition functions to extend the longevity of resin-dentin bonds.


Assuntos
Actinomyces/crescimento & desenvolvimento , Antibacterianos , Cimentos Dentários , Dentina/enzimologia , Inibidores de Proteases , Resinas Sintéticas , Streptococcus mutans/crescimento & desenvolvimento , Antibacterianos/química , Antibacterianos/farmacologia , Cimentos Dentários/química , Cimentos Dentários/farmacologia , Humanos , Inibidores de Proteases/química , Inibidores de Proteases/farmacologia , Resinas Sintéticas/química , Resinas Sintéticas/farmacologia
17.
J Dent ; 74: 79-89, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29702152

RESUMO

OBJECTIVES: The water-associated attributes of resin-dentin interfaces created by contemporary adhesives are important determinants of bond integrity and stability. In the present work, these attributes were estimated from the perspectives of causality, to examine the behavior of the first and most-recently launched versions of universal adhesives when applied in either the etch-and-rinse mode or the self-etch mode. METHODS: The immediate cause of interfacial permeability and the time-dependent cause of water sorption were investigated in conjunction with the intermediate effect of interface degradation and the more long-term effect of loss of mechanical strength, before and after thermomechanical cycling. The results were compared with control etch-and-rinse and self-etch adhesives. RESULTS: Although the introduction of this new class of universal adhesives has brought forth significant changes to the dental adhesion arena, including more application options, reduced bonding armamentarium and increased user friendliness, the water-associated attributes that are critical for making resin-dentin bonds more durable to environmental challenges and less susceptible to degradation have remained unchanged at large, when compared with benchmarks established by former classes of adhesives. CONCLUSION: It appears that the current trend of adhesive development has brought forth significant changes but lacks the vigor that demarcates progress and technological sublimity. CLINICAL SIGNIFICANCE: The advent of the user friendly universal adhesives has brought forth significant changes to the dental adhesion arena. However, the elements that are critical for making resin-dentin bonds more durable to environmental challenges and less susceptible to degradation have remained unchanged at large.


Assuntos
Colagem Dentária/métodos , Adesivos Dentinários/química , Dentina/química , Cimentos de Resina/química , Água/química , Condicionamento Ácido do Dente/métodos , Resinas Compostas/química , Coroas , Esmalte Dentário , Materiais Dentários/química , Humanos , Teste de Materiais , Dente Serotino , Permeabilidade , Propriedades de Superfície , Resistência à Tração
18.
J Dent ; 73: 76-90, 2018 06.
Artigo em Inglês | MEDLINE | ID: mdl-29660488

RESUMO

INTRODUCTION: The present study reported the histological events that occurred in the radicular pulp of human mature teeth in the presence of medium/deep untreated caries lesions, and those teeth with restorations or direct pulp capping, with particular emphasis on the morphology of the canal wall dentine and the odontoblast layer. METHODS: Sixty-two teeth with medium/deep caries lesions, extensive restorations or after application of a direct pulp capping procedure were obtained from 57 subjects. Fourteen intact mature teeth served as controls. Stained serial sections were examined for the pulp conditions of the coronal pulp. The teeth were classified as those with pulpal inflammation, or those with healed pulps. Histological changes that occurred in the roots at the pulp-dentine junction were investigated in detail. RESULTS: All teeth (100%) in the experimental group showed pathologic changes in the radicular pulp, with varying amounts of tertiary dentine on the canal walls and absence of odontoblasts. These changes were identified from different portions of the canal wall surface. Non-adherent calcifications in the pulp tissue were observed in more than half of the specimens. Changes that deviate from classically-perceived histological relationships of the pulp-dentine complex were also observed in the radicular pulps of 33.7% of the control teeth. CONCLUSION: When challenged by bacteria and bacterial by-products invading dentinal tubules, odontoblasts in the radicular pulp may undergo cell death, possibly by apoptosis. This phenomenon may be caused by progressive root-ward diffusion of bacterial by-products, cytokines or reactive oxygen species through the pulp connective tissue. CLINICAL SIGNIFICANCE: Although the vitality of the dental pulp in teeth with deep dentinal caries may be maintained with direct pulp capping or pulpotomy, the repair tissue that is formed resembles mineralised fibrous connective tissues more than true tubular dentine.


Assuntos
Cárie Dentária/microbiologia , Cárie Dentária/patologia , Polpa Dentária/microbiologia , Polpa Dentária/patologia , Raiz Dentária/patologia , Adolescente , Adulto , Idoso , Apoptose , Hidróxido de Cálcio/uso terapêutico , Citocinas/metabolismo , Cárie Dentária/diagnóstico por imagem , Polpa Dentária/diagnóstico por imagem , Capeamento da Polpa Dentária , Cavidade Pulpar/anatomia & histologia , Cavidade Pulpar/patologia , Exposição da Polpa Dentária/patologia , Dentina/microbiologia , Dentina/patologia , Dentina Secundária/patologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Odontoblastos/microbiologia , Odontoblastos/patologia , Pulpite/patologia , Pulpotomia , Espécies Reativas de Oxigênio/metabolismo , Cicatrização , Adulto Jovem
19.
J Dent ; 72: 53-63, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29534887

RESUMO

OBJECTIVES: To evaluate the bonding performance, antibacterial activity, and remineralization effect on enamel of the orthodontic adhesive containing MAE-DB and NACP. METHODS: Eighty non-carious human premolars were divided into 3 groups: Transbond XT (TB), PEHB + 5% MAE-DB (PD), and PEHB + 40% NACP + 5% MAE-DB (PND). Premolars were bonded with orthodontic brackets, the first subgroup (n = 10) and the second subgroup (n = 10) were subjected to shear bond strength testing after immersed in water for 1 day and in demineralization solution for 28 days respectively and then tested surface roughness, while the third subgroup (n = 6) was used for microhardness evaluation after aged in demineralization solution for 28 days. For each adhesive, fifty disk samples were prepared for antibacterial study. Specimens measuring 12 mm × 2 mm × 2 mm were fabricated for ion release test. RESULTS: Bond strengths were in the order TB = PND > PND = PD for "1-day in water", and in the order TB = PND > PD for "28-days in pH 4 solution". No significant difference in the ARI scores for the three adhesive. Numerous bacteria adhered to TB surface, while PD and PND had minimal bacterial growth and activity. PND showed high levels of Ca and P ions release and enamel hardness. The surface roughness of enamel in PND was much lower than TB and PD and showed no significant difference with the sound, control enamel. CONCLUSION: PND adhesive with 5% MAE-DB and 40% NACP exhibits antibacterial and remineralizing capabilities, and did not adversely affect bond strength compared to commercial adhesive. CLINICAL SIGNIFICANCE: Novel adhesive containing quaternary ammonium monomer and nano-amorphous calcium phosphate represents a promising candidate in combating enamel white spot lesions and even dental caries.


Assuntos
Compostos de Amônio/química , Antibacterianos/química , Fosfatos de Cálcio/química , Cimentos Dentários/química , Nanopartículas/química , Remineralização Dentária , Adesinas Bacterianas/efeitos dos fármacos , Antibacterianos/farmacologia , Dente Pré-Molar , Biofilmes/efeitos dos fármacos , Colagem Dentária , Cárie Dentária/prevenção & controle , Cimentos Dentários/farmacologia , Esmalte Dentário , Combinação de Medicamentos , Dureza/efeitos dos fármacos , Humanos , Teste de Materiais , Metacrilatos/química , Braquetes Ortodônticos , Cimentos de Resina , Resistência ao Cisalhamento , Propriedades de Superfície
20.
Acta Biomater ; 67: 354-365, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29274477

RESUMO

Intrafibrillar silicified collagen scaffold (SCS) is a promising biomaterial for bone regeneration because it promotes cell homing and angiogenesis in bone defects via monocyte modulation. In the present study, a rat femoral defect model was used to examine the contribution of monocyte signaling pathways to SCS modulation. Activation of the monocyte p38 signaling pathway by SCS resulted in monocyte differentiation into TRAP-positive mononuclear cells. These cells demonstrated increased secretion of SDF-1α, VEGFa and PDGF-BB, which, in turn, promoted homing of bone marrow stromal cells (BMSCs) and endothelial progenitor cells (EPCs), as well as local vascularization. Monocyte differentiation and secretion were blocked after inhibition of the p38 pathway, which resulted in reduction in cell homing and angiogenesis. Taken together, these novel findings indicate that the p38 signaling pathway is crucial in SCS-modulated monocyte differentiation and secretion, which has a direct impact on SCS-induced bone regeneration. STATEMENT OF SIGNIFICANCE: Intrafibrillar silicified collagen scaffold (SCS) is a promising biomaterial for bone regeneration. The present work demonstrates that SCS possesses favorable bone regeneration potential in a rat femoral defect model. The degrading scaffold modulates monocyte differentiation and release of certain cytokines to recruit MSCs and EPCs, as well as enhances local vascularization by activating the p38 MAPK signaling pathway. These findings indicate that SCS contributes to bone defect regeneration by stimulating host cell homing and promoting local angiogenesis and osteogenesis without the need for loading cytokines or xenogenous stem cells.


Assuntos
Regeneração Óssea/fisiologia , Colágenos Fibrilares/farmacologia , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Monócitos/enzimologia , Dióxido de Silício/química , Tecidos Suporte/química , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismo , Animais , Regeneração Óssea/efeitos dos fármacos , Citocinas/metabolismo , Modelos Animais de Doenças , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Fêmur/patologia , Masculino , Camundongos Endogâmicos C57BL , Monócitos/efeitos dos fármacos , Osteogênese/efeitos dos fármacos , Ratos , Ratos Sprague-Dawley
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