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Femtosecond laser ablation of dentin and enamel for fast and more precise dental cavity preparation.Materials Science & Engineering. C,... Sep 2018The purpose of the present work was to achieve fast and more precise ablation in dentin and enamel by using a commercial femtosecond laser system with high repetition...
PURPOSE
The purpose of the present work was to achieve fast and more precise ablation in dentin and enamel by using a commercial femtosecond laser system with high repetition rate, whilst avoiding any collateral irreversible damages in the hard tissue and pulp area.
METHODS
We used fluence of the incident laser pulses which was marginally higher than the ablation threshold for dentin and enamel. The study was based on the hypothesis that femtosecond laser operating with a repetition rate in the range of 100-500 kHz can controllably ablate dental tissue obtaining sufficiently high removal rate whilst avoiding any collateral irreversible damages in the hard tissue and pulp area.
RESULTS
The ablation yielded the formation of 1 mm craters with well-defined precise vertical cavity sides and edges. Advantageous high porosity and numerous interconnected pores were introduced in the ablated zones. Thermal load and hence collateral thermo-mechanical damages were avoided and the crystalline structure of the tooth constituent hydroxyapatite was preserved.
CONCLUSION
The ultrafast femtosecond laser used in our work hold the promise of a significant drilling ability without collateral thermomechanical effects. It achieves high processing efficiency, overcomes disadvantages of other laser systems reported and can be used to develop an instrument for cavity preparation based on fast and precise ablation. Our further aim is to exceed the speed of traditional drilling instruments and thus to reduce the treatment time which in turn will bring comfort to the patient.
Topics: Dental Cavity Preparation; Dental Enamel; Dentin; Humans; Laser Therapy
PubMed: 29853109
DOI: 10.1016/j.msec.2018.04.070 -
Caries Research 2015Dentin organic matrix, with type I collagen as the main component, is exposed after demineralization in dentinal caries, erosion or acidic conditioning during adhesive... (Review)
Review
Dentin organic matrix, with type I collagen as the main component, is exposed after demineralization in dentinal caries, erosion or acidic conditioning during adhesive composite restorative treatment. This exposed matrix is prone to slow hydrolytic degradation by host collagenolytic enzymes, matrix metalloproteinases (MMPs) and cysteine cathepsins. Here we review the recent findings demonstrating that inhibition of salivary or dentin endogenous collagenolytic enzymes may provide preventive means against progression of caries or erosion, just as they have been shown to retain the integrity and improve the longevity of resin composite filling bonding to dentin. This paper also presents the case that the organic matrix in caries-affected dentin may not be preserved as intact as previously considered. In partially demineralized dentin, MMPs and cysteine cathepsins with the ability to cleave off the terminal non-helical ends of collagen molecules (telopeptides) may lead to the gradual loss of intramolecular gap areas. This would seriously compromise the matrix ability for intrafibrillar remineralization, which is considered essential in restoring the dentin's mechanical properties. More detailed data of the enzymes responsible and their detailed function in dentin-destructive conditions may not only help to find new and better preventive means, but better preservation of demineralized dentin collagenous matrix may also facilitate true biological remineralization for the better restoration of tooth structural and mechanical integrity and mechanical properties.
Topics: Cathepsins; Collagenases; Cysteine Proteases; Dental Bonding; Dental Caries; Dentin; Humans; Matrix Metalloproteinase Inhibitors; Matrix Metalloproteinases; Tooth Remineralization
PubMed: 25661522
DOI: 10.1159/000363582 -
Tissue Engineering. Part B, Reviews Aug 2022The recent discovery of mesenchymal stem cells within periapical lesions (PL-MSC) has presented novel opportunities for managing periradicular diseases in adult teeth by... (Review)
Review
The recent discovery of mesenchymal stem cells within periapical lesions (PL-MSC) has presented novel opportunities for managing periradicular diseases in adult teeth by way of enhancing tissue regeneration. This discovery coincides with the current paradigm shift toward biologically driven treatment strategies in endodontics, which have typically been reserved for non-vital immature permanent teeth. One such approach that shows promise is utilizing local endogenous non-collagenous dentine extracellular matrix components (dECM) to recruit and upregulate the intrinsic regenerative capacity of PL-MSCs . At picogram levels, these morphogens have demonstrated tremendous ability to enhance the cellular activities in and animal studies that would otherwise be necessary for periradicular regeneration. Briefly, these include proliferation, viability, migration, differentiation, and mineralization. Therefore, topical application of dECMs during ortho- or retrograde root canal treatment could potentially enhance and sustain the regenerative mechanisms within diseased periapical tissues that are responsible for attaining favorable clinical and radiographic outcomes. This would provide many advantages when compared with conventional antimicrobial-only therapies for apical periodontitis (AP), which do not directly stimulate healing and have had stagnant success rates over the past five decades despite significant advances in operative techniques. The aim of this narrative review was to present the novel concept of exploiting endogenous dECMs as clinical tools for treating AP in mature permanent teeth. A large scope of literature was summarized to discuss the issues associated with conventional treatment modalities; current knowledge surrounding PL-MSCs; composition of the dECM; inductive potentials of dECM morphogens in other odontogenic stem cell niches; how treatment protocols can be adapted to take advantage of dECMs and PL-MSCs; and finally, the challenges currently impeding successful clinical translation alongside directions for future research. Impact statement Apical periodontitis (AP) is an inflammatory condition that is associated with a great degree of morbidity and ultimately leads to tooth loss. The purpose of this review was to summarize the current evidence pertaining to stem cell therapy in endodontics and present a novel clinical methodology through which they may be utilized to address AP. A comprehensive overview of the basic science, clinical translation, and potential challenges are presented in this review.
Topics: Animals; Cell Differentiation; Dentin; Periapical Periodontitis; Root Canal Therapy; Tissue Engineering
PubMed: 34309453
DOI: 10.1089/ten.TEB.2021.0074 -
The Journal of International Medical... Feb 2021The effects of saliva on demineralized dentin and silver diamine fluoride (SDF) were investigated
OBJECTIVE
The effects of saliva on demineralized dentin and silver diamine fluoride (SDF) were investigated
METHODS
Dentin samples stored in deionized water (DIW), buffer solution (BS), basal medium mucin (BMM), and unstimulated whole saliva (UWS) were demineralized for 3 days and immersed in the same storage media. SDF as a 38 mass% solution was applied to the dentin samples for 3 minutes after they had been replaced in their respective medium. Surfaces were analyzed by scanning electron microscopy, energy-dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD).
RESULTS
Scanning electron microscopy showed various surface deposits and coatings, including occlusion of dentinal tubules. DIW resulted in the thinnest coating, whereas BMM resulted in the thickest. EDX and XPS showed the formation of metallic silver and silver compounds in all four media, with the greatest formation in BS. XRD indicated that the main product was silver chloride except in DIW. Sulphur was found in BMM and UWS. EDX and XPS detected fluoride and XRD detected calcium fluoride and fluorohydroxyapatite in BS, BMM, and UWS.
CONCLUSION
The interaction between SDF and demineralized dentin was dependent upon the storage medium. BMM provided an outcome most similar to human saliva.
Topics: Dentin; Fluorides, Topical; Humans; Quaternary Ammonium Compounds; Silver Compounds
PubMed: 33615855
DOI: 10.1177/0300060520985336 -
International Journal of Nanomedicine 2021Dentin hypersensitivity (DH) is a common dental clinical condition presented with a short and sharp pain in response to physical and chemical stimuli. Currently no...
BACKGROUND
Dentin hypersensitivity (DH) is a common dental clinical condition presented with a short and sharp pain in response to physical and chemical stimuli. Currently no treatment regimen demonstrates long-lasting efficacy in treating DH, and unesthetic yellow tooth color is a concern to many patients with DH.
AIM
To develop a bi-functional material which can occlude dentinal tubules in-depth and remineralize dentin for long-lasting protection of the dentin-pulp complex from stimuli and bleach the tooth at the same time.
METHODS
A mixture containing CaO, HPO, polyethylene glycol and HO at a specific ratio was mechanically ground using a planetary ball. The mineralizing complex paste was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Dentin was exposed to the synthesized paste for 8 h and 24 h . The mineralizing property was evaluated using SEM and microhardness tests. Red tea-stained tooth slices were exposed to the synthesized paste for 8 h and 24 h . The bleaching effect was characterized by a spectrophotometer.
RESULTS
The complex paste had very a fine texture, was injectable, and had a gel-like property with 2.6 (mass/volume) % HO concentration. The X-ray diffraction pattern showed that the inorganic phase was mainly monetite (CaHPO). The mineralizing complex paste induced the growth of inorganic crystals on the dentin surface and in-depth occlusion of dentin tubules by up to 80 μm. The regenerated crystals were integrated into the dentin tissue on the dentin surface and the wall of dentinal tubules with a microhardness of up to 126 MPa (versus 137 Mpa for dentin). The paste also bleached the stained dental slices.
CONCLUSION
The mineralizing complex paste is a promising innovative material for efficient DH management by remineralizing dentin and in-depth occlusion of dentin tubules, as well as tooth bleaching.
Topics: Calcium Phosphates; Dentin; Hardness; Humans; Hydrogen Peroxide; Phosphoric Acids; Tooth Bleaching; Tooth Remineralization; X-Ray Diffraction
PubMed: 33442248
DOI: 10.2147/IJN.S287393 -
International Journal of Nanomedicine 2024This study was to investigate a novel antibacterial biomimetic mineralization strategy for exploring its potential application for root canal disinfection when...
OBJECTIVE
This study was to investigate a novel antibacterial biomimetic mineralization strategy for exploring its potential application for root canal disinfection when stabilized cerium oxide was used.
MATERIAL AND METHODS
A biomimetic mineralization solution (BMS) consisting of cerium nitrate and dextran was prepared. Single-layer collagen fibrils, collagen membranes, demineralized dentin, and root canal system were treated with the BMS for mineralization. The mineralized samples underwent comprehensive characterization using various techniques, including transmission electron microscopy (TEM), high-resolution TEM (HRTEM), Fourier transform infrared spectroscopy (FTIR), scanning transmission electron microscopy (STEM), selected-area electron diffraction (SAED), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and micro-CT. Additionally, the antimicrobial properties of the BMS and the remineralized dentin were also analyzed with broth microdilution method, live/dead staining, and SEM.
RESULTS
Cerium ions in the BMS underwent a transformation into cerium oxide nanoparticles, which were deposited in the inter- and intra-fibrillar collagen spaces through a meticulous bottom-up process. XPS analysis disclosed the presence of both Ce (III) and Ce (IV) of the generated cerium oxides. A comprehensive examination utilizing SEM and micro-CT identified the presence of cerium oxide nanoparticles deposited within the dentinal tubules and lateral canals of the root canal system. The BMS and remineralized dentin exhibited substantial antibacterial efficacy against E. faecalis, as substantiated by assessments involving the broth dilution method and live/dead staining technique. The SEM findings revealed the cell morphological changes of deceased E. faecalis.
CONCLUSION
This study successfully demonstrated antibacterial biomimetic mineralization as well as sealing dentinal tubules and lateral branches of root canals using cerium nitrate and dextran. This novel biomimetic mineralization could be used as an alternative strategy for root canal disinfection.
Topics: Dental Pulp Cavity; Dentin; Disinfection; Dextrans; Cerium; Microscopy, Electron, Scanning; Collagen; Anti-Bacterial Agents
PubMed: 38179219
DOI: 10.2147/IJN.S441060 -
Journal of Applied Oral Science :... 2016To determine the organic matter dissolution and changes in dentin chemical composition promoted by different concentrations of NaOCl over time.
OBJECTIVES
To determine the organic matter dissolution and changes in dentin chemical composition promoted by different concentrations of NaOCl over time.
MATERIAL AND METHODS
Fragments of bovine muscle tissue were weighed before and after 5, 10, and 15 min of immersion in the groups (n=10): G1- 0.9% saline solution; G2- 1% NaOCl; G3- 2.5% NaOCl; and G4- 5% NaOCl. Bovine dentin fragments were subjected to the same irrigants and absorption spectra were collected by Attenuated Total Reflectance of Fourier Transform Infrared Spectroscopy (ATR-FTIR) before and after 0,5, 1, 2, 3, 5, 8, and 10 min of immersion in the solutions. The ratios of the amide III/phosphate and carbonate/phosphate absorption bands were determined. The tissue dissolution and carbonate/phosphate ratios were submitted to the two-way analysis of variance (ANOVA) with Tukey's multiple-comparison test (α<0.05) and to the one-way analysis of variance with Tukey's (α<0.05). The amide III/phosphate ratio was analyzed by Friedman test (α<0.05) and the Kruskal-Wallis test with Dunn's post-hoc (α<0.05).
RESULTS
The increase in NaOCl concentration and contact time intensified the dissolution of organic matter and dentin collagen with reduction in the amide III/phosphate ratio. Significant differences between all groups (p<0.05) were observed in the dissolution of organic matter at 10 min and in the amide III/phosphate ratio between the saline solution and 5% NaOCl at 5 min. The carbonate/phosphate ratio decreased significantly in G2, G3, and G4 after 0,5 min of immersion (p<0.05), but more alterations did not occur in the subsequent periods (p>0.05). Intergroup differences were not observed in this ratio (p>0.05).
CONCLUSIONS
The increase in the exposure time and in the concentration of NaOCl solution lead to an increase in the tissue dissolution and dentin collagen deproteination. Furthermore, some carbonate ions are removed from the dentin inorganic phase by the NaOCl.
Topics: Animals; Cattle; Collagen; Dentin; Disinfectants; Hydrogen-Ion Concentration; Immersion; Muscles; Reference Values; Root Canal Irrigants; Sodium Hypochlorite; Solubility; Spectroscopy, Fourier Transform Infrared; Surface Properties; Time Factors
PubMed: 27383711
DOI: 10.1590/1678-775720150524 -
International Endodontic Journal May 2022Assess whether sodium hypochlorite (NaOCl) or chlorhexidine (CHX) and two irrigation protocols may alter the antibacterial properties of dentine and three endodontic...
AIM
Assess whether sodium hypochlorite (NaOCl) or chlorhexidine (CHX) and two irrigation protocols may alter the antibacterial properties of dentine and three endodontic sealers using a novel ex vivo tooth model.
METHODOLOGY
Prior to antibacterial testing, the tooth model was validated by means of scanning electron microscopy (SEM) to evaluate the separation between dentine and sealer surfaces. Root blocks prepared from extracted human roots were pre-treated with 17% EDTA + 0.9% saline and subsequently treated with 1% NaOCl (G1), 2% CHX (G2) or no irrigant (G3). Two irrigation protocols were further investigated, "1% NaOCl + 17% EDTA" (P1) and "1% NaOCl + 17% EDTA + 2% CHX" (P2). Following irrigation, the root blocks were either filled with AH Plus, BioRoot RCS and Pulp Canal Sealer (PCS), or left empty. All groups were incubated for 1, 7 and 28 days. Direct contact tests for planktonic E. faecalis and 48 h E. faecalis biofilms were performed at the level of dentine and sealer surfaces. Statistical analysis was performed on the bacterial survival between irrigants (G1, G2 and G3) and between irrigation protocols (P1 and P2); p < .05.
RESULTS
The model was considered reproducible as SEM examination of dentine samples indicated consistent separation between dentine and sealer surfaces. Irrigation with CHX (G2) and irrigation protocol P2 enhanced the antibacterial properties of dentine without sealer application as well as dentine in contact with all three sealers tested, especially against planktonic E. faecalis. G2 and P2 also improved the antibacterial effect of AH Plus surfaces for all three incubation times. No irrigation groups (G1, G2) or irrigation protocols (P1, P2) altered the antibacterial properties of BioRoot RCS surfaces against planktonic bacteria or biofilms. Only BioRoot RCS surfaces eliminated the planktonic E. faecalis in all irrigation groups (G1, G2, G3) and protocols (P1, P2) investigated whilst PCS surfaces eliminate E. faecalis in biofilms in all groups up to 7 days.
CONCLUSIONS
The tooth model was reproducible. CHX improved the antibacterial activity upon both sealer and dentine surfaces. Amongst sealers, BioRoot RCS was less affected by NaOCl and CHX, and exhibited high antibacterial properties regardless the irrigation applied.
Topics: Anti-Bacterial Agents; Chlorhexidine; Dental Pulp Cavity; Dentin; Edetic Acid; Enterococcus faecalis; Humans; Root Canal Irrigants; Sodium Hypochlorite
PubMed: 35080277
DOI: 10.1111/iej.13692 -
Clinical Oral Investigations Apr 2022The aim of this study was to evaluate the effectiveness of different fiber post removal techniques and to correlate dentinal loss with microcrack formation.
OBJECTIVES
The aim of this study was to evaluate the effectiveness of different fiber post removal techniques and to correlate dentinal loss with microcrack formation.
MATERIALS AND METHODS
Forty-five extracted single-rooted teeth were root canal treated and fiber posts were adhesively luted. Specimens were divided into three groups (n = 15) according to the removal technique: long-shaft round bur (EndoTracer #08, Komet, Lemgo, Germany), SonicFlex Endo (KaVo, Biberach, Germany), DT Post Removal Kit (VDW, Munich, Germany). Roots were scanned before post cementation and after post removal using micro-computed tomography. Dentin loss, residual luting material, working time, and the induction of microcracks were assessed. Statistical analysis was performed by using multiple contrast tests (max-t tests, α = 0.05). Correlations between parameters dentin loss/new microcracks and dentin loss/residual material were calculated using Kendall's tau.
RESULTS
Post removal with SonicFlex Endo resulted in the highest amount of removed dentin with significant differences to the round bur and the DT Post Removal Kit. No technique was found to completely remove the post and luting material. All techniques induced microcracks with the DT Post Removal Kit presenting the highest number of new defects. No correlation between dentin loss and new microcracks was observed. Deviations from the original root canal occurred in all groups, but no perforation was observed.
CONCLUSIONS
All techniques resulted in dentin loss, residual luting material, and the formation of microcracks. However, no correlation between dentin loss and the induction of microcracks was observed.
CLINICAL RELEVANCE
As all techniques resulted in microcrack formation and dentin loss, this study emphasizes the risk of iatrogenic damage due to post removal procedures.
Topics: Dental Pulp Cavity; Dentin; Post and Core Technique; Root Canal Preparation; Tooth Root; X-Ray Microtomography
PubMed: 34893941
DOI: 10.1007/s00784-021-04338-0 -
International Journal of Molecular... Aug 2021The aim of this study was to evaluate the effect of different concentrations of chitosan polymer on dentinal enzymatic activity by means of gelatin and in situ...
The aim of this study was to evaluate the effect of different concentrations of chitosan polymer on dentinal enzymatic activity by means of gelatin and in situ zymography. Human dentin was frozen and ground in a miller. Dentin powder aliquots were demineralized with phosphoric acid and treated with three different concentrations of lyophilized chitosan polymer (1, 0.5 and 0.1 wt%) dissolved in distilled water. Dentin proteins were extracted from each experimental group and electrophoresed under non-reducing conditions in 10% SDS-PAGE containing fluorescein-labeled gelatin. After 48 h in the incubation buffer at 37 °C, proteolytic activity was registered under long-wave UV light scanner and quantified by using Image J software. Furthermore, additional teeth ( = 4) were prepared for the in situ zymographic analysis in unrestored as well as restored dentin pretreated with the same chitosan primers. The registered enzymatic activity was directly proportional to the chitosan concentration and higher in the restored dentin groups ( < 0.05), except for the 0.1% chitosan primer. Chitosan 0.1% only showed faint expression of enzymatic activity compared to 1% and 0.5% concentrations. Chitosan 0.1% dissolved in water can produce significant reduction in MMPs activity and could possibly contribute to bond strength preservation over time.
Topics: Chelating Agents; Chitosan; Dentin; Humans; Materials Testing; Matrix Metalloproteinases
PubMed: 34445554
DOI: 10.3390/ijms22168852