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1.
Braz. j. oral sci ; 20: e219320, jan.-dez. 2021. ilus
Artigo em Inglês | LILACS, BBO - Odontologia | ID: biblio-1253013

RESUMO

Aim: This study analyzed the effect of whitening mouth rinses on water sorption (WS), solubility (SL), color change, and surface roughness of a nanofilled composite. Whitening perceptibility and acceptability (WID) were also studied. Methods: Forty specimens of Filtek Z350XT, shade EA2 were produced and randomly distributed (n=8) to AS ­ artificial saliva (control); LWE ­ Listerine Whitening Extreme; CLW ­ Colgate Luminous White; LCM ­ Listerine Cool Mint; and CP ­ Colgate Plax. They were immersed in the mouth rinses 2x/day, for one minute, during 28 days. The color was assessed using an Easyshade spectrophotometer (CIE-L*a*b* system). Surface roughness (Ra-µm) was measured with three parallel measures, using an RP-200 roughness meter. The WS and SL (µg/mm-3) were analyzed based on the ISO 4049 recommendations. The data were analyzed using one- and two-way ANOVA/Tukey tests (α=0.05). Results: Surface roughness significantly increased after immersion in AS and LCM, with no significant differences between the groups either before or after immersion. The ΔE* was not significantly different between the groups. All substances produced a ΔWID higher than the 50%:50% perceptibility and acceptability thresholds. The WS and SL were not significantly affected by the mouth rinses. Conclusion: Whitening mouth rinses did not affect WS, SL, surface roughness, and color stability of a nanofilled composite, regardless of the presence of ethanol in the composition


Assuntos
Cor , Resinas Compostas , Medicamentos sem Prescrição , Clareadores Dentários , Antissépticos Bucais
2.
Braz. j. oral sci ; 20: e213641, jan.-dez. 2021. ilus
Artigo em Inglês | LILACS, BBO - Odontologia | ID: biblio-1254539

RESUMO

Aim: To review the current literature regarding the bond strength of self-adhesive flowable resin composites (SAFRCs) to tooth structure, comparing the outcomes with conventional flowable resin composites (CFRCs). Methods: PubMed/Medline, EbscoHost and Scopus databases were screened (last update on November 2020) using related Medical Subject Headings (MeSH) and free terms. We included in vitro studies published in English language comparing the bond strength of SAFRCs and CFRCs to enamel and/or dentin from primary and/or permanent teeth. Results: In total, 23 articles were included. Unlike CFRCs, SAFRCs such as Vertise® Flow and Fusio™ Liquid Dentin exhibited statistically lower bond strength to enamel and dentin from permanent teeth. There were limited studies comparing the enamel bond strength of CFRCs and SAFRCs (prior phosphoric acid etching and/or adhesive system use). Also, we found few studies that evaluated the bonding effectiveness of Constic® and other SAFRCs to primary teeth. Conclusions: Current SAFRCs showed low bond strength to permanent teeth, which impedes to recommend them as a reliable alternative to CFRCs. The bonding performance of Constic® on both hard dental tissues should be evaluated on future studies. Also, more evidence assessing the bond strength of SAFRCs to primary teeth and etched enamel is needed


Assuntos
Colagem Dentária , Resinas Compostas , Revisões Sistemáticas como Assunto
3.
Braz. j. oral sci ; 20: e219022, jan.-dez. 2021. ilus
Artigo em Inglês | LILACS, BBO - Odontologia | ID: biblio-1254545

RESUMO

Minimally invasive dentistry is based on conservative techniques for the treatment of initial caries lesions, the so-called white spot lesions. One of the conservative maneuvers includes the use of enamel resin infiltrant: a low viscosity material that penetrates the enamel pores to stop lesion progression. Aim: Therefore, this case report aimed to describe the clinical case of a 28-year-old female patient under routine consultation, in which a radiographic examination showed the presence of two incipient caries lesions in the left upper premolars. Methods: The application of a resin infiltrating agent (Icon®, DMG ­ Hamburg, Germany) was chosen as treatment to stop caries lesions progression. Conclusion: The use of this conservative technique can be considered a promising approach for the prevention of dental tissue wear, and the resin infiltrant is considered an effective material


Assuntos
Humanos , Feminino , Resinas Compostas , Cárie Dentária , Tratamento Conservador
4.
Braz. j. oral sci ; 20: e212755, jan.-dez. 2021. ilus
Artigo em Inglês | LILACS, BBO - Odontologia | ID: biblio-1254632

RESUMO

Aim: To investigate restorative decisions made by dentists and to examine what demographic characteristics are associated with the decisions for managing approximal and occlusal lesions. Methods: A questionnaire was randomly sent to 900 Palestinian dentists. It noted the demographic details of the dentists and the years of experience. The questionnaire evaluated the respondents for their treatment decisions regarding approximal and occlusal carious lesions. The data was analyzed using the IBM SPSS statistics for windows. The associations between gender and years of experience of the respondents and their restorative decisions were assessed. Results: The response rate was 58.2%. For occlusal carious lesions, 93.9% of the respondents would postpone operative treatment until the lesion was in dentine (grade 3 to 5). For approximal lesions, intervention was deemed appropriate by 92.6% of the respondents when there was radiographic evidence of a carious lesion reaching the DEJ or deeper. Around 53% preferred to prepare approximal lesions according to the traditional principles of cavity preparation. For both approximal and occlusal lesions, the participants opted for resin composites. Statistically, there was a significant association between the restorative decisions with the years since graduation and gender. Conclusion: The study showed variations between the treatment decisions of Palestinian dentists. The subjects chose conservative treatment plans but still adhered to traditional learned practices especially when cavity preparation for approximal lesions was concerned. The years since graduation and gender played a significant role in the choice of treatment opted for. Resin composites seemed to be a popular choice for treatment


Assuntos
Humanos , Masculino , Feminino , Características da População , Inquéritos e Questionários , Resinas Compostas , Padrões de Prática Odontológica , Cárie Dentária , Preparo da Cavidade Dentária
5.
Braz. j. oral sci ; 20: e213981, jan.-dez. 2021. ilus
Artigo em Inglês | LILACS, BBO - Odontologia | ID: biblio-1254747

RESUMO

Aim: To compare the microleakage of Cention N, a subgroup of composite resins with a resin-modified glass ionomer (RMGI) and a composite resin. Methods: Class V cavities were prepared on the buccal and lingual surfaces of 46 extracted human molars. The teeth were randomly assigned to four groups. Group A: Tetric N-Bond etch-and-rinse adhesive and Tetric N-Ceram nanohybrid composite resin, group B: Cention N without adhesive, group C: Cention N with adhesive, and group D: Fuji II LC RMGI. The teeth were thermocycled between 5°-55°C (×10,000). The teeth were coated with two layers of nail vanish except for 1 mm around the restoration margins, and immersed in 2% methylene blue (37°C, 24 h) before buccolingual sectioning to evaluate dye penetration under a stereomicroscope (×20). The data were analyzed by the Kruskal-Wallis and Wilcoxon tests (α=0.05). Results: Type of material and restoration margin had significant effects on the microleakage (p<0.05). Dentin margins showed a higher leakage score in all groups. Cention N and RMGI groups showed significant differences at the enamel margin (p=0.025, p=0.011), and for the latter group the scores were higher. No significant difference was found at the dentin margins between the materials except between Cention N with adhesive and RMGI (p=0.031). Conclusion: Microleakage was evident in all three restorative materials. Cention N groups showed similar microleakage scores to the composite resin and displayed lower microleakage scores compared with RMGI


Assuntos
Resinas Compostas , Infiltração Dentária , Cimentos de Ionômeros de Vidro , Dente Serotino
7.
Chin J Dent Res ; 24(3): 159-166, 2021 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-34491010

RESUMO

OBJECTIVE: To evaluate adhesives' enamel bonding performance utilising the traditional microtensile bond strength test (µTBST) and a new double-sided microtensile bond strength test (DµTBST) to assess the suitability of the latter. METHODS: A 'tug-of-war' direct encounter design was employed to compare the enamel bond strengths of two universal adhesives and their different application modes simultaneously under the same tensile load applied to double-sided bonded specimens. Clearfil Universal Bond (CU; Kuraray, Kurashiki, Japan) and Scotchbond Universal Adhesive (SB; 3M ESPE, St Paul, MN, USA) were applied in self-etch (S) and etch-and-rinse (E) mode on 110 human molar samples to perform two experiments. Experiment 1 compared the enamel bond strengths of the combinations of adhesive application modes utilising µTBST. The data were analysed using a Welch analysis of variance (ANOVA), followed by a Games-Howell test. Experiment 2 employed DµTBST to determine the suitability of the new double-sided bonded assembly and ascertain which of the adhesive application mode combinations was superior. The data were analysed using a Kaplan-Meier survival analysis, followed by pairwise comparisons with a Mantel-Cox log-rank test. The level of significance was set at P ˂ 0.05. RESULTS: The µTBST results did not show significant differences for CUE vs CUS, SBE vs SBS, CUS vs SBS and CUS vs SBE (P ˃ 0.05); however, from DµTBST, the survival distributions for the interventions were statistically significantly different (χ2(3) = 145.130, P ˂ 0.0005), indicating the superiority of universal adhesive CU over SB and application mode E over S with certainty. CONCLUSION: DµTBST was able to add more discerning outcomes to the µTBST results, indicating that the new technique could become a valuable adjunct to the conventional method.


Assuntos
Colagem Dentária , Adesivos Dentinários , Condicionamento Ácido do Dente , Resinas Compostas , Cimentos Dentários , Esmalte Dentário , Dentina , Humanos , Teste de Materiais , Cimentos de Resina , Resistência à Tração
8.
Chin J Dent Res ; 24(3): 185-189, 2021 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-34491013

RESUMO

OBJECTIVE: To evaluate the clinical performance of direct composite restorations using the modified stamp technique (MST) in vivo. METHODS: A total of 30 posterior teeth with undermining caries were randomly divided into two groups and then restored using the MST and conventional technique (CT), respectively. 3D images of the occlusal surface were obtained using an intraoral scanner (CEREC Omnicam, Dentsply Sirona, Charlotte, NC, USA) before and after treatment and the differences between these two 3D images were analysed with reverse engineering software. Statistical analysis was performed using a one-way analysis of variance (ANOVA) combined with a least significant difference (LSD) post hoc test using SPSS 20.0 software (IBM, Armonk, NY, USA). RESULTS: The statistical analysis revealed that the average root mean square (RMS) values of best fit alignment errors were significantly different between groups (P < 0.01). The average RMS values in the MST and CT groups were 0.0738 ± 0.0279 and 0.1638 ± 0.0682, respectively. The LSD post hoc test revealed that the value was significant smaller in the MST group than in the CT group. CONCLUSION: The MST was effective in direct composite restoration. The morphological consistency of the occlusal surface using the MST was better than with the CT.


Assuntos
Desenho Assistido por Computador , Dente , Resinas Compostas , Restauração Dentária Permanente , Imageamento Tridimensional
9.
Int J Mol Sci ; 22(16)2021 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-34445545

RESUMO

Six novel urethane-dimethacrylate analogues (QAUDMAs) were synthesized and characterized. They consisted of the 2,4,4,-trimethylhexamethylene diisocyanate (TMDI) core and two methacrylate-terminated wings containing quaternary ammonium groups substituted with alkyl chains of 8, 10, 12, 14, 16, or 18 carbon atoms. QAUDMAs, due to the presence of quaternary ammonium groups, may have possible antibacterial effects. Since they showed satisfactory physicochemical properties, they will be subjected to further research towards the development of dental composites with a capacity to reduce secondary caries. The synthesis of QAUDMAs included three stages: (i) transesterification of methyl methacrylate (MMA) with N-methyldiethanolamine (MDEA), (ii) N-alkylation of the tertiary amino group with alkyl bromide, and (iii) addition of TMDI to the intermediate achieved in the second stage. The formation of QAUDMAs was confirmed by 1H and 13C NMR. They were characterized for density (dm), viscosity (η), refractive index (RI), glass transition temperature (Tg), polymerization shrinkage (S), and degree of conversion (DC). QAUDMAs were yellow, viscous resins (the η values ranged from 1.28 × 103 to 1.39 × 104 Pa·s, at 50 °C). Their RI ranged from 1.50 to 1.52, Tg from -31 to -15 °C, DC from 53 to 78%, and S from 1.24 to 2.99%, which is appropriate for dental applications.


Assuntos
Compostos de Amônio/química , Resinas Compostas/síntese química , Metacrilatos/química , Poliuretanos/química , Teste de Materiais , Projetos Piloto , Polimerização , Propriedades de Superfície , Viscosidade
10.
Int J Mol Sci ; 22(15)2021 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-34360861

RESUMO

In response to the demand for high-performance materials, epoxy thermosetting and its composites are widely used in various industries. However, their poor toughness, resulting from the high crosslinking density of the epoxy network, must be improved to expand their application to the manufacturing of flexible products. In this study, ductile epoxy thermosetting was produced using thiol compounds with functionalities of 2 and 3 as curing agents. The mechanical properties of the epoxy were further enhanced by incorporating fumed silica into it. To increase the filler dispersion, epoxide-terminated polydimethylsiloxane was synthesized and used as a composite component. Thanks to the polysiloxane-silica interaction, the nanosilica was uniformly dispersed in the epoxy composites, and their mechanical properties improved with increasing fumed silica content up to 5 phr (parts per hundred parts of epoxy resin). The toughness and impact strength of the composite containing 5 phr nanosilica were 517 (±13) MJ/m3 and 69.8 (±1.3) KJ/m2, respectively.


Assuntos
Resinas Compostas/síntese química , Resinas Epóxi/síntese química , Dimetilpolisiloxanos/química , Teste de Materiais , Dióxido de Silício/química , Propriedades de Superfície , Resistência à Tração
11.
Hua Xi Kou Qiang Yi Xue Za Zhi ; 39(4): 453-457, 2021 Aug 01.
Artigo em Inglês, Chinês | MEDLINE | ID: mdl-34409802

RESUMO

OBJECTIVES: This work aimed to evaluate the ability of two kinds of antioxidants, namely, grape-seed extract and sodium ascorbate, in restoring bond strength at the resin-enamel interface after bleaching. METHODS: Ten groups of samples with 15 teeth per group were prepared for shear-bond-strength test at the resin-enamel interface after bleaching. The groups were as follows: control; no antioxidant; 2.5%, 5%, 10%, or 15% grape-seed extract; and 2.5%, 5%, 10%, or 15% sodium ascorbate. The peak values of shear bond strength when resin was debonded from teeth and the failure modes under a microscope were recorded. Ten other groups of teeth with two teeth per group were prepared and treated in a similar approach before resin bonding. The samples were cut vertically to the bonding interface. The structures of the bonding interface were compared by scanning electron microscopy. RESULTS: No statistically significant difference in shear bond strength was found among the no-antioxidant, 2.5% grape-seed extract, and 2.5%, 5%, or 10% sodium ascorbate groups (P>0.05), which were statistically significantly lower than the control group (P<0.05). Evidence of marginal gap was observed at the resin-enamel interface, and resin tags in enamel were short, poorly defined, and fragmented. No statistically significant difference in shear bond strength was found among 5%, 10%, or 15% grape-seed extract, 15% sodium ascorbate, and control groups (P>0.05). No evidence of discontinuity was found at the adhesion interface, and resin tags in enamel were long, well defined, and structurally intact. Failure in the adhesive joint was the major debond mode in all experimental groups. CONCLUSIONS: Immediately after bleaching, the bond strength of dental enamel significantly decreased. Bond strength can be restored by 5% grape-seed extract or 15% sodium ascorbate in 5 min.


Assuntos
Colagem Dentária , Clareamento Dental , Antioxidantes , Resinas Compostas , Cimentos Dentários , Esmalte Dentário , Humanos , Resistência ao Cisalhamento
12.
J Contemp Dent Pract ; 22(6): 620-623, 2021 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-34393117

RESUMO

AIM AND OBJECTIVE: The aim of this study was to evaluate the extent of microleakage beneath stainless steel orthodontic brackets bonded with different adhesive systems. MATERIALS AND METHODS: Freshly extracted 60 human premolar teeth from mandibular arch were included in this study. After sterilizing all teeth, they were stored in thymol solution of 1% for further preparation. Acrylic blocks were used to mount the teeth in a way their roots were totally implanted up to the cement enamel junction in acrylic with crown being visible. A 0.022 slot, stainless steel preadjusted edgewise premolar brackets were taken. Sixty premolars were categorized randomly into three groups (20 premolars in each group) as follows: group I: flowable composite, group II: Fuji Ortho LC, group III: Transbond XT. Later, all the samples were subjected to thermocycling and tested immediately and 24 hours after water storage. The samples were submerged for 24 hours in methylene blue solution (2%) at room temperature. A ×20 magnification stereomicroscope was used to examine all samples. RESULTS: The lowest microleakage (1.34 ± 0.20) was shown by Transbond XT restored teeth, followed by flowable composite group (1.79 ± 0.32) and Fuji Ortho LC group (2.98 ± 0.13). An analysis of variance showed statistically significant differences among various adhesive systems. A statistically significant difference (p <0.05) among groups I and II, and groups II and III adhesive materials was seen. CONCLUSION: This study demonstrated microleakage in all the examined adhesive groups but the lowest microleakage was found with Transbond XT group followed next by Filtek Z350 XT group and Fuji Ortho LC group. CLINICAL SIGNIFICANCE: Due to microleakage, the bacteria and fluids present intraorally penetrate through the gaps along the enamel-adhesive boundary. This penetration results in significant esthetic and clinical complications. Such problems related to microleakage can be addressed with the use of an appropriate adhesive agent.


Assuntos
Colagem Dentária , Braquetes Ortodônticos , Resinas Compostas , Cimentos Dentários , Estética Dentária , Humanos , Teste de Materiais , Cimentos de Resina , Aço Inoxidável
13.
J Contemp Dent Pract ; 22(6): 630-636, 2021 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-34393119

RESUMO

AIM AND OBJECTIVE: To chemically characterize restorative composite resin polymerized with 20 wt.% and 40 wt.% dipentaerythritol penta-/hexaacrylate (DPEPHA) comonomer. Furthermore, this study aimed to evaluate the conversion degree (DC) and glass transition temperature (Tg) of the newly formed copolymer. MATERIALS AND METHODS: The trial groups were photo-polymerized with DPEPHA comonomer, whereas the control group was photo-polymerized only with the propriety resin monomers. Infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopies were used for establishing copolymerization. The characteristics and composition (mass %) of the surface were explained by field-emission scanning electron microscopy (FESEM) and energy-dispersive X-ray (EDX) spectroscopy, respectively. The DC and Tg of the resultant copolymers were evaluated through FTIR and differential scanning calorimetry, respectively. Appropriate statistical tests with corresponding post hoc tests were employed to compare the medians and means of DC and Tg, respectively. RESULTS: The formation of a new copolymer P(GEU-Co-DPEPHA) was evident. The DC and Tg of the P(GEU-Co-DPEPHA) copolymer were greater than the control. DPEPHA in the copolymer at 40 wt.% concentration showed the highest DC and Tg. CONCLUSION: DPEPHA comonomer addition leads to the formation of a new P(GEU-Co-DPEPHA) copolymer with improved DC and Tg. CLINICAL SIGNIFICANCE: The novel P(GEU-Co-DPEPHA) copolymer may improve the physico-mechanical and biological properties of the restorative composite resin. This would improve the quality of restoration and its in vivo serviceability, thereby imparting a good living quality to the entailed population.


Assuntos
Resinas Compostas , Vidro , Teste de Materiais , Metacrilatos , Polimerização , Propriedades de Superfície , Temperatura
14.
J Contemp Dent Pract ; 22(6): 650-654, 2021 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-34393122

RESUMO

AIM AND OBJECTIVE: This study was undertaken to compare postoperative sensitivity in posterior class I restorations using etch-and-rinse and self-etch composite resins, GC Fuji IX, and Cention-N. MATERIALS AND METHODS: The sample size consisted of 160 participants. After clinical and radiographic examination, the participants were randomly assigned to four groups consisting of 40 participants each according to the restorative materials used. Class I cavity was prepared and was restored on each patient and after restoration postoperative sensitivity was evaluated at 24 h, 48 h, and 7 days using the visual analog scale (VAS). The results were tabulated and statistically analyzed using analysis of variance (ANOVA) and post-hoc multiple comparison tests. RESULTS: There were significant differences present between the groups at 24 h, 48 h, and 7 days. We found that the materials causing least postoperative sensitivity are ranked according to superiority as GC Fuji IX > nano-hybrid composite using self-etch adhesive > Cention-N > nano-hybrid composite using etch-and-rinse adhesive. CONCLUSION: Both GC Fuji IX and self-etch adhesive showed less postoperative sensitivity as compared to etch-and-rinse and Cention-N at 24 h. With GC Fuji IX and self-etch adhesive postoperative sensitivity was decreased while Cention-N also showed good results at 48 h and 7 days. Etch-and-rinse adhesive showed maximum postoperative sensitivity as compared to other groups at 24 h, 48 h, and 7 days. CLINICAL SIGNIFICANCE: Teeth restored with resin composites are susceptible to sensitivity. The restorative material used and their handling can influence postoperative sensitivity.


Assuntos
Cárie Dentária , Restauração Dentária Permanente , Resinas Compostas , Materiais Dentários , Adesivos Dentinários , Humanos , Cimentos de Resina
15.
J Contemp Dent Pract ; 22(6): 686-690, 2021 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-34393128

RESUMO

AIM: To compare and evaluate the mechanical properties of 2.5% titanium dioxide nanoparticle (TiO2 NP) incorporated as filler in an experimental composite resin with everX Flow and MultiCore Flow. MATERIALS AND METHODS: TiO2 was prepared and incorporated into experimental dental composite resin. The experimental and traditional composite resin was grouped as follows: Group I: The experimental composite resin with 2.5% of TiO2 fillers, Group II: everX Flow (GC EUROPE), and Group III: MultiCore Flow (Ivoclar Vivadent). Based on International Standards Organization (ISO) 4049, the samples were prepared for the compressive, diametral tensile, and flexural test. RESULTS: Statistical analysis was done, and the results were tabulated. Compared to the other tested materials, the experimental composite resin had relatively high compressive strength, diametral tensile strength, and flexural strength. Compared to MultiCore Flow, the everX Flow showed strong mechanical properties. CONCLUSION: Based on the result of the study, it can be concluded that the 2.5% TiO2 NP incorporated as filler in an experimental composite resin demonstrated higher mechanical properties compared to the conventional material. CLINICAL SIGNIFICANCE: The unique photoactivities of TiO2 NP and their superior mechanical properties make them one of the ideal additives to enhance the performance of polymeric materials.


Assuntos
Resinas Compostas , Nanopartículas , Humanos , Teste de Materiais , Resistência à Tração , Titânio
16.
J Indian Prosthodont Soc ; 21(3): 287-294, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34380817

RESUMO

Aim: The aim of this study was to evaluate and compare the peel bond strength of an autopolymerizing acrylic resin and a fiberreinforced composite (FRC) resin to a heat temperature vulcanizing maxillofacial silicone (M511) using two different primers. Settings and Design: In vitro - comparative study. Materials and Methods: Autopolymerizing acrylic resin and FRC resin specimens with a dimension of 75 mm (length) ×10 mm (width) × 3 mm (height) were fabricated. A total of 60 samples were split into six categories based on the substructure material and primers (A330G primer and Sofreliner tough primer) used to bond the maxillofacial silicone to the FRC and acrylic resin specimens. In a universal testing machine, the peel bond strength was conducted at a 10 mm/min crosshead speed until bonding failure occurred. Statistical Analysis Used: The t-test, one-way analysis of variance, and the Tukey's honest significant difference (post hoc test) tests were used to statistically assess the values. Results: The Sofreliner tough primer produced the greatest peel bond strength in both the acrylic resin (0.89690 N/mm) and the FRC resin groups (3.19860 N/mm). Adhesive failures predominated in the acrylic resin group regardless of the primer used. The FRC group showed predominantly cohesive failures with both the A330G primer and Sofreliner tough primer. Conclusion: This study suggests that FRC resin combined with Sofreliner tough primer can significantly enhance the peel bond strength.


Assuntos
Resinas Acrílicas , Prótese Maxilofacial , Resinas Compostas , Teste de Materiais , Silicones , Resistência à Tração
17.
Beijing Da Xue Xue Bao Yi Xue Ban ; 53(4): 764-769, 2021 Aug 18.
Artigo em Chinês | MEDLINE | ID: mdl-34393242

RESUMO

OBJECTIVE: To evaluate the influence of base materials on stress distribution in endodontically treated maxillary premolars restored with endocrowns using three-dimensional finite element analysis. METHODS: A maxillary second premolar was scanned by Micro-CT and a three-dimensional finite element model of ceramic endocrown with 1 mm thickness of base was established. A model without base was also established as a negative control. Four kinds of conventional base materials with different elastic modulus were adopted: light cure glass ionomer(3M Vitrebond, 3 657 MPa), flowable composite resin(3M Filtek Z350XT Flowable Restorative, 7 300 MPa), high strength glass ionomer(GC Fuji Ⅸ, 13 130 MPa), and posterior composite resin(3M Filtek P60, 19 700 MPa). With a 200 N force loaded vertically and obliquely, the distribution and magnitude of stress in the tooth tissue and adhesive layer were investigated by three-dimensional finite element analysis. RESULTS: The maximum von Mises stress values(vertical/oblique) in dentin and adhesive layer were measured as follows: (1) no base material: 19.39/70.49 MPa in dentin and 6.97/17.97 MPa in adhesive layer; (2) light cure glass ionomer: 19.00/69.75 MPa in dentin and 6.87/16.30 MPa in adhesive layer; (3) flowable composite resin: 18.78/69.33 MPa in dentin and 6.79/16.17 MPa in adhesive layer; (4) high strength glass ionomer: 18.71/69.20 MPa in dentin and 6.74/16.07 MPa in adhesive layer; (5) posterior composite resin: 18.61/69.03 MPa in dentin and 6.70/16.01 MPa in adhesive layer. Under the same loading condition, models with different elastic moduli of base materials had similar stress distribution patterns. The von Mises stress of tooth tissue was mainly concentrated in the tooth cervix. Under oblique load, the regions where von Mises stress concentrated in were similar to those under a vertical load, but the values increased. The stress concentration in the tooth cervix was alleviated in models with base materials compared with the model without base material. The maximum von Mises stress in the tooth tissue and adhesive layer decreased when the elastic modulus of base materials increased and got close to that of dentin. CONCLUSION: The posterior composite resin of which the elastic moduli is high and close to that of dentin is recommended as base material for premolar endocrowns to alleviate the concentration of stress in tooth cervix and adhesive layer.


Assuntos
Resinas Compostas , Colo do Dente , Dente Pré-Molar , Cerâmica , Análise do Estresse Dentário , Dentina , Análise de Elementos Finitos , Humanos , Teste de Materiais , Estresse Mecânico , Microtomografia por Raio-X
18.
Am J Dent ; 34(4): 179-185, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34370908

RESUMO

PURPOSE: To compare the effect of the immediate dentin sealing (IDS) and resin cement type on fracture resistance of Class II mesio-occluso-distal (MOD) zirconia inlay restorations. METHODS: 90 Class II MOD cavities on freshly extracted human mandibular third molars, prepared with a high-speed handpiece, were divided into two groups: those with IDS (CR+) and without IDS (CR-). The CEREC system was used to prepare zirconia inlays from Katana super translucent multi-layered blocks. The inlays were cemented with one of three resin cements: RelyX Unicem 2 (RU), Multilink Automix (MA), or Super-Bond (SB). These specimens were stored in water at 37°C for 24 hours and exposed to 5,000 thermal cycles. A vertical load was applied with a metal sphere (Φ 6-mm) on a material testing system, with a crosshead speed of 0.5 mm/minute, until the specimen fractured. Fracture resistance was measured for each tooth, and the fractures were categorized according to Burke's classification. Statistical analyses were conducted using two-way ANOVA and Tukey's honest significant difference tests (P< 0.05). RESULTS: No significant differences in tooth fracture resistance were identified between the CR+ and CR- groups. The SB group had a significantly higher fracture resistance compared to that of the MA group. Fracture morphology showed many mode IV fractures in all groups. IDS did not affect tooth fracture resistance, although there was a significant difference in tooth fracture resistance for different resin cement types used with Class II MOD zirconia inlay restorations. CLINICAL SIGNIFICANCE: Zirconia inlay restorations provide excellent mechanical performance, morphology, and esthetic appearance. In vitro, zirconia inlays cemented with any luting resin cement restored tooth fracture resistance to levels similar to that of intact teeth. Fracture resistance varied among the different resin cements.


Assuntos
Cimentos de Resina , Fraturas dos Dentes , Resinas Compostas , Porcelana Dentária , Análise do Estresse Dentário , Dentina , Humanos , Restaurações Intracoronárias , Teste de Materiais , Zircônio
19.
J Indian Soc Pedod Prev Dent ; 39(2): 178-182, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34341238

RESUMO

Introduction: The primary function of corono-radicular post is to provide retention for the core and to reinforce and to replace the remaining coronal tooth structure. There is considerable controversy regarding optimal choice of the material. An ideal post system should exhibit fracture resistance higher than the average masticatory forces. Finite elemental analysis (FEA) method facilitates precise analysis of the distribution and magnitude of stresses at any point of complex and irregular structures. Thus, this FEA study has been undertaken to evaluate the fracture stress distribution patterns in three fiber posts, viz., carbon, glass fiber, and everStick with an FEA. Materials and Methods: The FE stress analysis was performed with the FE software program (CATIA). Three two-dimensional FEA models of central incisor were simulated, and elastic moduli and Poisson's ratio of all the materials were fed to the software. For all the models, a 200 N vertical force was applied on the lingual surface of the tooth at an angle of 45°. Stress concentration and distribution were evaluated and noted down for all the models. To evaluate the stresses within the restored tooth, the modified von Mises failure criterion was used. The equivalent stresses found in the tested models were compared with the tensile strength of the respective materials. Contact stresses in the luting cement-dentin interface were calculated. Results: Finite element method revealed that maximum stress concentration was at the point of stress application. The stress value was highest in carbon fiber post followed by glass fiber post and least stresses found in everStick post. Maximum stress was observed at the labial surfaces of crown. However, the stress values and distribution were more homogenous in everStick post. Conclusion: The present findings suggest that everStick post has uniform stress distribution within tooth structure.


Assuntos
Técnica para Retentor Intrarradicular , Resinas Compostas , Coroas , Materiais Dentários , Análise do Estresse Dentário , Dentina , Análise de Elementos Finitos , Vidro , Humanos , Estresse Mecânico
20.
Compend Contin Educ Dent ; 42(8): e5-e9, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34433283

RESUMO

As dental composite materials have evolved, their properties and overall quality have improved. New composites can be ideal for simplifying highly esthetic, long-lasting, minimally invasive restorations in a timely manner. This article presents two cases in which a universal composite with a chameleon effect was used in anterior restorations to achieve exceptional blending and a natural-looking appearance with the adjacent dentition. The cases demonstrate techniques for enhanced cosmetic dentistry.


Assuntos
Resinas Compostas , Estética Dentária , Materiais Dentários , Humanos , Propriedades de Superfície
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