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1.
Biomed Res Int ; 2021: 9731280, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34368356

RESUMO

A fluoride-releasing adhesive system is expected to promote mineralization of demineralized dentin/enamel around a composite restoration, thereby contributing to the longevity of the restoration. Scanning electron microscopic (SEM) and transmission electron microscopic (TEM) observations revealed the formation of an "acid-base resistant zone" (ABRZ) beneath the hybrid layer when dentin was treated with a self-etch adhesive system. A thicker ABRZ was formed from the upper slope to the end of the outer lesion, indicating greater resistance against an acid-base challenge, when a fluoride-releasing self-etch adhesive system was used. The slope formation of a fluoride-releasing adhesive is believed to be due to fluoride-release from the adhesive. Quantitative assessment of the acid resistance was performed at the interface using the region of interest (ROI) mode of a digital image analysis software package. The area of the ABRZ is influenced by the concentration of fluoride release from the adhesive resin. The threshold of fluoride concentration in the adhesive may exist to influence the morphology of the ABRZ. X-ray absorption fine structure (XAFS) analysis of the dentin treated with different concentrations of NaF-mouth rinses suggested that different fluoride concentrations result in the formation of different chemical compounds, such as fluorapatite and CaF2-like structures, on the dentin surface. This may explain the differences in µTBS values and morphological appearance of the ABRZ. NaF is effective in enhancing the enamel/dentin bond durability and also helps create a high quality of ARBZ to improve the clinical success of restorations.


Assuntos
Condicionamento Ácido do Dente , Ácidos/química , Adesivos/química , Álcalis/química , Fluoretos/análise , Dentina/ultraestrutura
2.
Biomed Res Int ; 2021: 5534294, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33869625

RESUMO

Aim: Root canal filling materials have the tendency to inhibit adhesion of resin-based composites. This study was aimed at evaluating the effect of root canal filling materials and their solvents on the shear bond strength (SBS) of resin composite with the primary tooth dentin. Methods and Materials: Seventy-two intact anterior primary teeth were selected. Smooth dentinal surfaces were prepared to a minimum diameter of 3 mm and thickness of 1.5-2.0 mm. The samples were equally divided into six groups (n = 12). In group 1: control group, no root filling material; in group 2: Metapex, no solvent; in group 3: Metapex+ethanol solvent; in group 4: ZOE, no solvent; in group 5: ZOE+ethanol solvent; and in group 6: ZOE+orange oil solvent were applied. Then, dentin surfaces were etched, and composite restorations were placed and cured. The specimens were stored in distilled water at 37°C for 24 hours. SBS values were determined using a universal testing machine. Results: The SBS values of composite to dentin in groups 2 and 4 were significantly lower than those in the control group (P < 0.001). Cleansing of the specimens with 96% ethanol after removal of Metapex significantly increased the composite-dentin bond (P < 0.001). Applying ZOE, only orange oil solvent significantly increased the SBS of the composite to the primary tooth dentin (P = 0.01). Conclusion: To reduce the negative effects of endodontic root filling materials on the SBS of composite and primary tooth dentin, ethanol is a suitable solvent when Metapex is used, while orange oil might be a better choice than ethanol when applying ZOE.


Assuntos
Resinas Compostas/química , Colagem Dentária , Dentina/efeitos dos fármacos , Materiais Restauradores do Canal Radicular/farmacologia , Resistência ao Cisalhamento/efeitos dos fármacos , Solventes/química , Dente Decíduo/química , Dentina/ultraestrutura , Humanos , Propriedades de Superfície
3.
Int J Nanomedicine ; 16: 31-45, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33442248

RESUMO

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, H3PO4, polyethylene glycol and H2O2 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 in vitro. 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 in vitro. 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) % H2O2 concentration. The X-ray diffraction pattern showed that the inorganic phase was mainly monetite (CaHPO4). 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.


Assuntos
Fosfatos de Cálcio/farmacologia , Ácidos Fosfóricos/farmacologia , Clareamento Dental , Dentina/efeitos dos fármacos , Dentina/ultraestrutura , Dureza , Humanos , Peróxido de Hidrogênio/análise , Remineralização Dentária , Difração de Raios X
4.
Lasers Med Sci ; 36(2): 447-454, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32696424

RESUMO

The purpose of this study was to investigate the shear bond strength (SBS) of ceramic discs luted to differently etched enamel and dentin surfaces. Occlusal surfaces of 64 carious-free human molars and vestibule surfaces of 64 first maxillary incisors were ground to get flat superficial dentin and flattened enamel respectively. After generating 4 groups according to the surface etching method (37% orthophosphoric acid, Er:YAG laser-contact handpiece/scanning handpiece (1 or 2 times of scanning)), ceramic discs were luted to the surfaces with adhesive resin cement (Variolink N, Vivadent Ets., Schaan/Liechtenstein). After etching and cementation, thermocycling of 5000 cycles (Sd Mechatronik Gmbh, Feldkirchen-Westerham, Germany) and SBS test (Servopulser EHFFD1; Shimadzu, Kyoto, Japan) were performed respectively. The surface morphologies of 2 specimens, etched enamel and dentin, prepared for each group were examined with SEM analysis. Failure modes were determined under a USB digital microscope. Data were analyzed with one-way analysis of variance (ANOVA) and Tukey HSD test (α = 0.05). SBS values in dentin surfaces showed statistically significant differences (p < 0.05) among tested groups. The highest SBS among dentin groups was determined in the group which had 2 times etching by Er:YAG laser (11.42 MPa) by a scanning handpiece. No statistical differences were observed in the other dentin or enamel groups. Laser etching seems to be a viable alternative to acid etching on both enamel and dentin surfaces while double etching of dentin with a scanning handpiece can improve the adhesion.


Assuntos
Cimentação , Cerâmica/química , Colagem Dentária , Esmalte Dentário/efeitos da radiação , Corrosão Dentária , Dentina/efeitos da radiação , Lasers de Estado Sólido , Cimentos de Resina/química , Esmalte Dentário/ultraestrutura , Dentina/ultraestrutura , Humanos , Ácidos Fosfóricos/química , Resistência ao Cisalhamento
5.
Lasers Med Sci ; 36(1): 219-226, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32869119

RESUMO

This study aims to evaluate the effect of Nd:YAG and femtosecond lasers irradiation on the shear bond strength (SBS) of a self-adhesive resin cement to the human dentin surface. One hundred extracted third molar teeth were randomly divided into 10 experimental groups according to dentin surface treatments; with and without the bonding agent, Nd:YAG 302 J/cm2 and 440 J/cm2, femtosecond 4 J/cm2 and 7 J/cm2, and control groups were prepared. After surface treatments, a self-adhesive resin cement was luted by using a bonding jig (Ultradent Products Inc.). The specimens were then subjected to shear test at a crosshead speed of 0.5 mm/min, and failure loads were recorded as megapascal (MPa). Two-way analysis of variance and Tukey HSD tests were performed (p Ë‚ 0.05). Representative specimens from each experimental subgroup were examined by means of SEM. The highest SBS values were obtained in Group 302 J/cm2 Nd:YAG with bonding agent, and there is no statistical difference between Group 440 J/cm2 Nd:YAG with bonding and Group 7 J/cm2 femtosecond with bonding (p > 0.05). The lowest SBS values were observed in Group control without bonding agent. Nd:YAG and femtosecond laser treatments improved the adhesion between the dentin surface and the self-adhesive resin cement.


Assuntos
Dentina/efeitos dos fármacos , Dentina/efeitos da radiação , Lasers de Estado Sólido , Cimentos de Resina/farmacologia , Análise de Variância , Colagem Dentária , Dentina/ultraestrutura , Humanos , Resistência ao Cisalhamento , Estresse Mecânico
6.
PLoS One ; 15(9): e0238590, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32941456

RESUMO

The aim of this study was to evaluate the effect of silver diamine fluoride and grape seed extract on the microstructure and mechanical properties of carious dentin following exposure to acidic challenge. Ninety-eight molars with occlusal caries were used. In the control group the specimens were kept in distilled water. In the GSE group, the specimens were immersed in 6.5% grape seed extract solution for 30 minutes. In the SDF group, the specimens were immersed in 30% SDF solution for 4 minutes. In the GSE+SDF group, the specimens were immersed in 6.5% grape seed extract solution for 30 minutes and then exposed to 30% SDF solution for 4 minutes. All the groups underwent pH cycling model for 8 days. Microhardness measurements were taken at the baseline before surface treatments and after pH cycling. Elastic modulus was measured, after pH cycling. In the control group, the final hardness was significantly lower than the initial hardness (P = 0.001). In the SDF group, the final hardness was significantly higher than the initial hardness (P < 0.001). There was no significant difference between the initial and final hardness values in the GSE and GSE + SDF groups (p = 0.92, p = 0.07). The H1-H0 in the SDF group was significantly higher than the other groups (P<0.05). Moreover, elastic modulus of the experimental groups except GSE+SDF group was significantly higher than control. The highest mean elastic modulus was detected in the SDF group (P<0.001). The use of SDF and GSE prior to the acid challenge improved mechanical properties. Microstructural investigation, using scanning electron microscope showed dentin structure protection against acid challenges with SDF treatment and collagen matrix stabilization with GSE treatment. However combined use of these agents was not beneficious.


Assuntos
Ácidos/efeitos adversos , Dentina/efeitos dos fármacos , Extrato de Sementes de Uva/farmacologia , Proantocianidinas/farmacologia , Substâncias Protetoras/farmacologia , Compostos de Amônio Quaternário/farmacologia , Compostos de Prata/farmacologia , Fenômenos Biomecânicos/efeitos dos fármacos , Dentina/ultraestrutura , Módulo de Elasticidade/efeitos dos fármacos , Fluoretos Tópicos/farmacologia , Humanos
7.
Microsc Res Tech ; 83(9): 1118-1123, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32643268

RESUMO

In restorative dentistry, the in situ replication of intra-oral situations, is based on a non-invasive and non-destructive scanning electron microscopy (SEM) evaluation method. The technique is suitable for investigation restorative materials and dental hard- and soft-tissues, and its interfaces. Surface characteristics, integrity of interfaces (margins), or fracture analysis (chipping, cracks, etc.) with reliable resolution and under high magnification (from ×50 to ×5,000). Overall the current study aims to share detailed and reproducible information about the replica technique. Specific goals are: (a) to describe detailed each step involved in producing a replica of an intra-oral situation, (b) to validate an integrated workflow based on a rational sequence from visual examination, to macrophotography and SEM analysis using the replica technique; (c) to present three clinical cases documented using the technique. A compilation of three clinical situations/cases were analyzed here by means the replica technique showing a wide range of possibilities that can be reached and explored with the described technique. This guidance document will contribute to a more accurate use of the replica technique and help researchers and clinicians to understand and identify issues related to restorative procedures under high magnification.


Assuntos
Odontologia/métodos , Técnicas de Réplica/métodos , Dente/ultraestrutura , Adulto , Esmalte Dentário/ultraestrutura , Dentina/ultraestrutura , Feminino , Humanos , Microscopia Eletrônica de Varredura , Pessoa de Meia-Idade
8.
Sci Rep ; 10(1): 10970, 2020 07 03.
Artigo em Inglês | MEDLINE | ID: mdl-32620785

RESUMO

To study the antimicrobial effects of quaternary ammonium silane (QAS) exposure on Streptococcus mutans and Lactobacillus acidophilus bacterial biofilms at different concentrations. Streptococcus mutans and Lactobacillus acidophilus biofilms were cultured on dentine disks, and incubated for bacterial adhesion for 3-days. Disks were treated with disinfectant (experimental QAS or control) and returned to culture for four days. Small-molecule drug discovery-suite was used to analyze QAS/Sortase-A active site. Cleavage of a synthetic fluorescent peptide substrate, was used to analyze inhibition of Sortase-A. Raman spectroscopy was performed and biofilms stained for confocal laser scanning microscopy (CLSM). Dentine disks that contained treated dual-species biofilms were examined using scanning electron microscopy (SEM). Analysis of DAPI within biofilms was performed using CLSM. Fatty acids in bacterial membranes were assessed with succinic-dehydrogenase assay along with time-kill assay. Sortase-A protein underwent conformational change due to QAS molecule during simulation, showing fluctuating alpha and beta strands. Spectroscopy revealed low carbohydrate intensities in 1% and 2% QAS. SEM images demonstrated absence of bacterial colonies after treatment. DAPI staining decreased with 1% QAS (p < 0.05). Fatty acid compositions of dual specie biofilm increased in both 1% and 2% QAS specimens (p < 0.05). Quaternary ammonium silane demonstrated to be a potent antibacterial cavity disinfectant and a plaque inhibitor and can be of potential significance in eliminating caries-forming bacteria.


Assuntos
Anti-Infecciosos/farmacologia , Biofilmes/efeitos dos fármacos , Compostos de Amônio Quaternário/farmacologia , Silanos/farmacologia , Aminoaciltransferases/antagonistas & inibidores , Aderência Bacteriana/efeitos dos fármacos , Proteínas de Bactérias/antagonistas & inibidores , Proteínas de Bactérias/química , Proteínas de Bactérias/efeitos dos fármacos , Biofilmes/crescimento & desenvolvimento , Cisteína Endopeptidases , Cárie Dentária/tratamento farmacológico , Cárie Dentária/microbiologia , Placa Dentária/tratamento farmacológico , Placa Dentária/microbiologia , Dentina/efeitos dos fármacos , Dentina/microbiologia , Dentina/ultraestrutura , Desinfetantes/farmacologia , Humanos , Técnicas In Vitro , Lactobacillus acidophilus/efeitos dos fármacos , Lactobacillus acidophilus/fisiologia , Microscopia Eletrônica de Varredura , Simulação de Acoplamento Molecular , Boca/microbiologia , Streptococcus mutans/efeitos dos fármacos , Streptococcus mutans/fisiologia
9.
J Struct Biol ; 211(2): 107550, 2020 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-32553779

RESUMO

Life on earth is regulated by biological rhythms, some of which oscillate with a circadian, monthly or lunar cycle. Recent research suggests that there is a near weekly biorhythm that may exert an influence on human skeletal growth. Evidence for the timing of this biorhythm is retained in tooth enamel as the periodicity of Retzius lines. Studies report that Retzius periodicity (RP) relates to adult human stature and enamel thickness. Adult human stature is sexually dimorphic, and so is enamel thickness of maxillary third molars (M3) but not mandibular M3. Yet, previous studies report sex differences in RP are apparent in some populations but not others, and it is unknown if dimorphism in enamel thickness relates to RP. To further our understanding of this biorhythm we analysed sex-related variation in RP and its relationship with enamel thickness in a sample of M3's (n = 94) from adults in Northern Britain. Results reveal RP was significantly higher in our sample of female molars compared to those of males, which is consistent with the previously reported correlation between the biorhythm and adult stature. The RP of maxillary M3 related to sex differences in enamel thickness, but this relationship was not present in mandibular M3. Our results support previous findings suggesting that this biorhythm is sexually dimorphic and provide the first evidence that RP may be one factor influencing sex differences in enamel thickness. Our study also shows that correlations between RP and enamel thickness appear to be most readily detected for tooth types with sufficiently wide ranges of enamel thickness variation, as is the case for maxillary but not mandibular M3. Achieving a sufficient sample size was critical for detecting a sex difference in periodicity.


Assuntos
Esmalte Dentário/ultraestrutura , Dentina/ultraestrutura , Periodicidade , Caracteres Sexuais , Adulto , Esmalte Dentário/fisiologia , Dentina/fisiologia , Feminino , Humanos , Masculino , Mandíbula/fisiologia , Mandíbula/ultraestrutura , Dente Molar/fisiologia , Dente Molar/ultraestrutura , Dente/fisiologia , Dente/ultraestrutura
10.
Proc Natl Acad Sci U S A ; 117(23): 12636-12642, 2020 06 09.
Artigo em Inglês | MEDLINE | ID: mdl-32461359

RESUMO

Mammalian teeth are attached to the jawbone through an exquisitely controlled mineralization process: unmineralized collagen fibers of the periodontal ligament anchor directly into the outer layer of adjoining mineralized tissues (cementum and bone). The sharp interface between mineralized and nonmineralized collagenous tissues makes this an excellent model to study the mechanisms by which extracellular matrix macromolecules control collagen mineralization. While acidic phosphoproteins, localized in the mineralized tissues, play key roles in control of mineralization, the role of glycosaminoglycans (GAGs) is less clear. As several proteoglycans are found only in the periodontal ligament, it has been hypothesized that these inhibit mineralization of collagen in this tissue. Here we used an in vitro model based on remineralization of mouse dental tissues to determine the role of matrix GAGs in control of mineralization. GAGs were selectively removed from demineralized mouse periodontal sections via enzymatic digestion. Proteomic analysis confirmed that enzymatic GAG removal does not significantly alter protein content. Analysis of remineralized tissue sections by transmission electron microscopy (TEM) shows that GAG removal reduced the rate of remineralization in mineralized tissues compared to the untreated control, while the ligament remained unmineralized. Protein removal with trypsin also reduced the rate of mineralization, but to a lesser extent than GAG removal, despite a much larger effect on protein content. These results indicate that GAGs promote mineralization in mineralized dental tissues rather than inhibiting mineral formation in the ligament, which may have broader implications for understanding control of collagen mineralization in connective tissues.


Assuntos
Materiais Biomiméticos/metabolismo , Biomineralização , Colágeno/metabolismo , Dentina/metabolismo , Glicosaminoglicanos/metabolismo , Ligamento Periodontal/metabolismo , Animais , Apatitas/química , Materiais Biomiméticos/química , Dentina/ultraestrutura , Matriz Extracelular/metabolismo , Camundongos , Ligamento Periodontal/ultraestrutura , Proteoma
11.
Photobiomodul Photomed Laser Surg ; 38(5): 295-300, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32427552

RESUMO

Objective: To investigate the caries prevention effect of silver diamine fluoride (SDF) with a carbon dioxide (CO2) laser (λ = 10,600 nm) on dentin. Method: Human dentin slices (n = 10) were prepared and allocated to the following treatments: Group 1 (SDF)-slices received an SDF application. Group 2 (laser)-slices were irradiated with a CO2 laser. Group 3 (laser + SDF)-slices were irradiated with a CO2 laser, followed by an SDF application. Group 4 (negative control)-slices had no treatment. All of the slices were subjected to pH cycling for cariogenic challenge. Lesion depth, nanohardness, and chemical and morphological changes were assessed by microcomputed tomography (micro-CT), nanoindentation, and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS), respectively. Results: micro-CT determined lesion depths for groups 1-4 were 27 ± 6, 138 ± 32, 17 ± 5, and 182 ± 49 µm, respectively (p < 0.001; group 3 < group 1 < groups 2 and 4). The nanohardness values for groups 1-4 were 456 ± 109, 288 ± 5, 444 ± 142, and 258 ± 76 MPa, respectively (p = 0.003; groups 2 and 4 < groups 1 and 3). EDS determined that the calcium-to-phosphorus molar ratio for groups 1-4 were 1.26 ± 0.12, 1.07 ± 0.19, 1.37 ± 0.08, and 0.80 ± 0.17, respectively (p < 0.001; group 4 < group 2 < groups 1 and 3). SEM evidenced no ablation or cracking on the lased dentin surfaces. The treated dentin showed a relatively more intact and smoother surface morphology compared with the untreated dentin. Conclusions: SDF can reduce dentin demineralization against cariogenic challenge, and the caries preventive effect of SDF is further enhanced through CO2 laser irradiation.


Assuntos
Cárie Dentária/prevenção & controle , Dentina/efeitos dos fármacos , Dentina/efeitos da radiação , Lasers de Gás , Terapia com Luz de Baixa Intensidade , Compostos de Amônio Quaternário/farmacologia , Compostos de Prata/farmacologia , Dentina/ultraestrutura , Fluoretos Tópicos/farmacologia , Humanos , Microscopia Eletrônica de Varredura , Técnicas de Cultura de Tecidos
12.
Ultrastruct Pathol ; 44(3): 255-261, 2020 May 03.
Artigo em Inglês | MEDLINE | ID: mdl-32241201

RESUMO

BACKGROUND AND OBJECTIVES: To evaluate the sealing effects of different Chinese herbal medicines on dentinal tubules, and to provide a reference for the clinical treatment of dentin hypersensitivity. METHODS: Forty dentin slices prepared by freshly extracted bovine mandibular central incisors were randomly assigned to procyanidins, tannic acid, gallic acid, naringin, epigallocatechin gallate (EGCG), glycyrrhizic acid, paeonol, and blank groups. Dentin slices in each Chinese herbal medicine group were treated three times a day, each for 5 min, and then immersed in a remineralization solution for the rest of the time. Dentin slices in the blank group were directly immersed in the remineralization solution for 7 days. The dentinal tubule sealing effect was observed under the scanning electron microscope (SEM). RESULTS: SEM results showed that the dentinal tubules were almost completely open in the blank group, which was mostly open in the gallic acid, EGCG, glycyrrhizic acid, and paeonol groups, and were sealed in procyanidins, tannic acid, and naringin groups. Significant differences were detected in mean area, mean diameter of dentinal tubules, and mean plugging rate of dentinal tubules between the remaining Chinese herbal medicine groups and blank group (P < .05). Among them, the dentinal tubule sealing effect of procyanidins, tannic acid, and naringin was obvious. CONCLUSION: The findings suggested that procyanidins, tannic acid, and naringin can effectively seal dentinal tubules, which provided a basis for clinical treatment of dentin hypersensitivity.


Assuntos
Dentina/efeitos dos fármacos , Dentina/ultraestrutura , Medicamentos de Ervas Chinesas/farmacologia , Animais , Bovinos , Microscopia Eletrônica de Varredura
13.
J Synchrotron Radiat ; 27(Pt 2): 462-467, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-32153285

RESUMO

An investigation of the problems of X-ray imaging of dentinal tubules is presented. Two main points are addressed. In the first part of this paper, the problem of computer simulating tubule images recorded in a coherent synchrotron radiation (SR) beam has been discussed. A phantom material which involved a two-dimensional lattice of the tubules with parameters similar to those of dentin was considered. By a comparative examination of two approximations, it was found that the method of phase-contrast imaging is valid if the number of tubules along the beam is less than 100. Calculated images from a lattice of 50 × 50 tubules are periodic in free space but depend strongly on the distance between the specimen and the detector. In the second part, SR microtomographic experiments with millimetre-sized dentin samples in a partially coherent beam have been described. Tomograms were reconstructed from experimental projections using a technique for incoherent radiation. The main result of this part is the three-dimensional rendering of the directions of the tubules in a volume of the samples. Generation of the directions is possible because a tomogram shows the positions of the tubules. However, a detailed tubule cross-section structure cannot be restored.


Assuntos
Dentina/ultraestrutura , Síncrotrons , Simulação por Computador , Humanos , Microscopia de Contraste de Fase , Fótons , Microtomografia por Raio-X , Raios X
14.
Photobiomodul Photomed Laser Surg ; 38(3): 174-180, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31968180

RESUMO

Objective: To validate the capability of the dual wavelength laser (Er,Cr:YSGG and diode 940 nm) and the XP-Endoshaper and finisher in removing the smear layer from curved canals. Methods: Forty curved root canals were prepared using the R25 file of the Reciproc® system. The teeth were randomly divided into five groups: G1: negative control irrigated with distilled water, G2: positive control irrigated with EDTA 17% and a final rinse of NaOCl 3%, G3: XP-Endoshaper and finisher with EDTA 17%, G4: dual wavelength Er,Cr:YSGG (1.25 W, 50 Hz, 50 µs) and diode 940 nm (2 W, 50% DC), and G5: dual wavelength Er,Cr:YSGG (2 W, 20 Hz, 50 µs) and diode 940 nm (2 W, 50% DC). Laser scanning microscope images (1000 × ) were scored with the Hülsmann scoring system. Results: Superior smear layer removal was observed in G5 in comparison with G4, especially in the apical third of the canal. Furthermore, the XP-Endoshaper and finisher exhibited positive results in all parts of the canal. Conclusions: The higher power output of the Er,Cr:YSGG in the dual wavelength laser may be a suitable approach to remove the smear layer from the apical third of curved canals. Moreover, the XP-Endoshaper and finisher with EDTA could expose the dentinal tubules, however, the negative side effects of applying EDTA 17% for longer periods must be taken into consideration. This work is clinically significant as it addresses the main aim of endodontic treatment and provides a suitable method to remove the debris, smear layer, and bacterial remnants from the clinically challenging curved root canals.


Assuntos
Cavidade Pulpar/efeitos da radiação , Lasers Semicondutores , Lasers de Estado Sólido , Preparo de Canal Radicular/instrumentação , Camada de Esfregaço , Cavidade Pulpar/ultraestrutura , Dentina/efeitos da radiação , Dentina/ultraestrutura , Humanos , Técnicas In Vitro , Microscopia Eletrônica de Varredura , Distribuição Aleatória , Irrigantes do Canal Radicular/farmacologia , Propriedades de Superfície
15.
Microsc Res Tech ; 83(5): 514-522, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31912929

RESUMO

This study evaluated the shear bond strength (SBS) and internal marginal adaptation of pulp-capping materials to dentin. Flat occlusal deep dentin surfaces were produced and randomly assigned to two groups (sound or artificial caries-affected dentin). The specimens in each group were assigned to one of seven subgroups according to the materials used: Biodentine, Theracal LC, Ultra-Blend plus, Calcimol LC, ApaCal ART, EQUIA Forte, and Ionoseal. Buildups (3-mm inner diameter and 2-mm deep) were made over the dentin surfaces. The bonded specimens were tested under shear forces at a crosshead speed of 0.8 mm/min and fracture modes were determined using a stereomicroscope at 25× magnification. The materials were applied to the pulp floor of prepared Class I cavities and then the cavities were restored with composite resin. Restored molar teeth were subjected to 5,000 thermocycles and sectioned in a bucco-lingual direction. Resin replicas were made to determine the adaptation at the pulp floor with scanning electron microscopy. Significant differences were determined among both bond strengths and gap formations of the materials. EQUIA Forte applied to both dentin substrates had a significantly higher SBS than the other materials. The bond strength of each material was not influenced by the dentin condition. Biodentine (3.03%), EQUIA Forte (7.83%), and Theracal LC (13.37%) had lower gap formations compared to other materials but were not significantly different from each other.


Assuntos
Colagem Dentária , Capeamento da Polpa Dentária , Adesivos Dentinários/química , Dentina/química , Dentina/ultraestrutura , Polpa Dentária/ultraestrutura , Humanos , Técnicas In Vitro , Teste de Materiais , Microscopia Eletrônica de Varredura , Dente Molar
16.
Int J Nanomedicine ; 14: 9423-9435, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31819441

RESUMO

Introduction: Dentinogenesis imperfecta type 1 (OIDI) is considered a relatively rare genetic disorder (1:5000 to 1:45,000) associated with osteogenesis imperfecta. OIDI impacts the formation of collagen fibrils in dentin, leading to morphological and structural changes that affect the strength and appearance of teeth. However, there is still a lack of understanding regarding the nanoscale characterization of the disease, in terms of collagen ultrastructure and mechanical properties. Therefore, this research presents a qualitative and quantitative report into the phenotype and characterization of OIDI in dentin, by using a combination of imaging, nanomechanical approaches. Methods: For this study, 8 primary molars from OIDI patients and 8 primary control molars were collected, embedded in acrylic resin and cut into longitudinal sections. Sections were then demineralized in 37% phosphoric acid using a protocol developed in-house. Initial experiments demonstrated the effectiveness of the demineralization protocol, as the ATR-FTIR spectral fingerprints showed an increase in the amide bands together with a decrease in phosphate content. Structural and mechanical analyses were performed directly on both the mineralized and demineralized samples using a combination of scanning electron microscopy, atomic force microscopy, and Wallace indentation. Results: Mesoscale imaging showed alterations in dentinal tubule morphology in OIDI patients, with a reduced number of tubules and a decreased tubule diameter compared to healthy controls. Nanoscale collagen ultrastructure presented a similar D-banding periodicity between OIDI and controls. Reduced collagen fibrils diameter was also recorded for the OIDI group. The hardness of the (mineralized) control dentin was found to be significantly higher (p<0.05) than that of the OIDI (mineralized) dentine. Both the exposed peri- and intratubular dentinal collagen presented bimodal elastic behaviors (Young's moduli). The control samples presented a stiffening of the intratubular collagen when compared to the peritubular collagen. In case of the OIDI, this stiffening in the collagen between peri- and intratubular dentinal collagen was not observed and the exposed collagen presented overall a lower elasticity than the control samples. Conclusion: This study presents a systematic approach to the characterization of collagen structure and properties in OIDI as diagnosed in dentin. Structural markers for OIDI at the mesoscale and nanoscale were found and correlated with an observed lack of increased elastic moduli of the collagen fibrils in the intratubular OIDI dentin. These findings offer an explanation of how structural changes in the dentin could be responsible for the failure of some adhesive restorative materials as observed in patients affected by OIDI.


Assuntos
Colágeno/metabolismo , Dentinogênese Imperfeita/metabolismo , Osteogênese Imperfeita/metabolismo , Dentina/metabolismo , Dentina/ultraestrutura , Dentinogênese Imperfeita/diagnóstico por imagem , Elasticidade , Dureza , Humanos , Dente Molar , Osteogênese Imperfeita/diagnóstico por imagem , Fenótipo , Radiografia Interproximal , Espectroscopia de Infravermelho com Transformada de Fourier , Desmineralização do Dente
17.
Int J Mol Sci ; 20(21)2019 Oct 29.
Artigo em Inglês | MEDLINE | ID: mdl-31671751

RESUMO

The removal or modification of smear layers that cover the dentin is critical to allow the penetration of adhesive molecules and to ensure a strong bond between resin and dentin. Aiming to establish a model for clinically-relevant dentin-bond testing, we evaluated the effects of smear layers created by abrasives having similar coarseness (180-grit SiC paper; fine-grit diamond bur) and application modes (single application; double application) on the microtensile bond strengths (µTBS) of two currently available universal adhesives (G-Premio Bond; Scotchbond Universal Adhesive) and a two-step self-etch adhesive (Clearfil Megabond 2). Sixty extracted human third molars were used for the µTBS test. Data were analyzed by three-way ANOVA and Tukey's test (α = 0.05). Fracture modes were determined using stereomicroscopy. An additional 24 third molars were prepared for observation of the resin-dentin interface by TEM and adhesive-smear layer interaction by SEM. µTBS was significantly affected by the adhesives and their application modes (p < 0.001), implying that the double application of universal adhesives should be recommended to improve their performance. The effect of smear layers was not significant (p > 0.05), indicating that 180-grit SiC papers could be used to prepare dentin as a substitute for fine-grit diamond burs for dentin-bond testing in laboratory settings.


Assuntos
Adesivos/química , Colagem Dentária/métodos , Adesivos Dentinários/química , Camada de Esfregaço/química , Estresse Mecânico , Resistência à Tração , Resinas Compostas/química , Dentina/ultraestrutura , Humanos , Teste de Materiais , Microscopia Eletrônica de Transmissão , Dente Serotino , Cimentos de Resina , Propriedades de Superfície
18.
Nan Fang Yi Ke Da Xue Xue Bao ; 39(9): 1113-1117, 2019 Sep 30.
Artigo em Chinês | MEDLINE | ID: mdl-31640964

RESUMO

OBJECTIVE: To explore the histological structure of the deciduous teeth and the tooth germs of Tibetan miniature pigs for studies of dental tissue diseases and tooth regeneration. METHODS: The structure of the deciduous teeth of Tibetan miniature pigs was observed by X-ray. The ultrastructure of the enamel and dentin of deciduous teeth was characterized by scanning electron microscopy. The jaws and teeth were three-dimensionally reconstructed using Mimics software based on Micro-CT scanning of the deciduous teeth. Image J software was used to calculate the gray value and the mineralization density of the deciduous teeth. Hisotological structure of the tooth germ and the pulp tissue of Tibetan miniature pigs was observed using HE staining. RESULTS: The deciduous teeth of Tibetan miniature pigs were composed of enamel, dentin and medullary pulp tissue. The permanent tooth germ were formed during the deciduous dentition. The enamel and dentin ultrastructure of deciduous teeth were consistent with that of human deciduous teeth. The enamel and dentin mineralization densities were 2.47±0.09 g/cm3 and 1.72±0.07 g/cm3, respectively. The pathological structures of tooth germ and pulp tissue were similar to those of human teeth, and the pulp tissue of the deciduous teeth was in an undifferentiated state. CONCLUSIONS: The deciduous teeth of Tibetan miniature pig have similar anatomy, ultrastructure and histopathological structure to human teeth and can serve as a good animal model for studying human dental tissue diseases and the mechanisms of tooth regeneration.


Assuntos
Porco Miniatura , Dente Decíduo/anatomia & histologia , Animais , Esmalte Dentário/ultraestrutura , Polpa Dentária , Dentina/ultraestrutura , Suínos , Tibet , Germe de Dente
19.
Acta Biomater ; 100: 388-397, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31568874

RESUMO

Long-term anti-bacterial effect is a desired ability of any dental material in combating tooth caries as one of the most common and widespread persistent diseases today. Among several cationic quaternary ammonium compounds with antiseptic properties, cetylpyridinium chloride (CPC) is often used in mouthrinses and toothpastes. In this study, we incorporated CPC in a soft phyllosilicate mineral (clay), referred to as montmorillonite (Mont), to enable gradual CPC release with rechargeability. Besides measuring CPC release and recharge, we examined the anti-bacterial effect, cytotoxicity and bonding effectiveness of five experimental adhesive formulations, prepared by adding 1 and 3 wt% CPC_Mont, 3 wt% Mont (without CPC), and 1 and 3 wt% CPC (without Mont) to the commercial adhesive Clearfil S3 Bond ND Quick ('C-S3B'; Kuraray Noritake). Strong inhibition of Streptococcus mutans biofilm formation by CPC_Mont adhesives was confirmed by optical density and SEM. CPC release from CPC_Mont adhesives was higher and lasted longer than from CPC adhesives, while CPC_Mont adhesives could also be recharged with CPC upon immersion in 2 wt% CPC. In conclusion, CPC_Mont technology rendered adhesives anti-bacterial properties with recharge ability, this without reducing its bonding potential, neither increasing its cytotoxicity. STATEMENT OF SIGNIFICANCE: Dental caries is one of the most prevalent chronic diseases in the population worldwide and is the major cause of tooth loss. In this study, we developed cetylpyridinium chloride (CPC) loaded montmorillonite (CPC-Mont) with a long-term antibacterial efficacy to prevent caries. CPC is an antibacterial agent approved by FDA, used as an OTC drug and contained in oral hygiene aids. CPC-Mont was incorporated in a dental adhesive to gradually release CPC. CPC_Mont technology rendered adhesives anti-bacterial properties with rechargeability, this without reducing its bonding potential, neither increasing its cytotoxicity.


Assuntos
Adesivos/farmacologia , Anti-Infecciosos/farmacologia , Bentonita/farmacologia , Cetilpiridínio/farmacologia , Animais , Morte Celular/efeitos dos fármacos , Linhagem Celular , Dentina/ultraestrutura , Liberação Controlada de Fármacos , Camundongos , Testes de Sensibilidade Microbiana , Pós , Streptococcus mutans/efeitos dos fármacos , Streptococcus mutans/crescimento & desenvolvimento , Difração de Raios X
20.
Microsc Res Tech ; 82(11): 1884-1890, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31400189

RESUMO

Determining surface topography of different tissues of the molar tooth with novel analytical methods has opened new horizons in dental surface measurements which characterize tooth surface quality in dentistry. Studying surface topological measurements and comparing surface morphology of hard tissue of the molar tooth are the ultimate goals of the present study. Ten molar teeth have been chosen for investigating their surface characteristics through image processing techniques. The power spectral density (PSD) and fast Fourier transform algorithms of every molar tooth containing enamel, dentin, and cementum have determined that the characterization of surface profiles is possible. As can be seen, PSD along with fractal dimensions leads to good results for teeth surface topography. Moreover, PSD angular plot assures appropriate description of surface.


Assuntos
Cemento Dentário/ultraestrutura , Esmalte Dentário/ultraestrutura , Dentina/ultraestrutura , Fractais , Dente Molar/ultraestrutura , Adulto , Cristalografia por Raios X , Análise de Fourier , Dureza/fisiologia , Humanos , Masculino , Microscopia de Força Atômica , Dente Molar/diagnóstico por imagem , Propriedades de Superfície
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