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La alta prevalencia de desgaste dental erosivo producido por la ingestión frecuente de bebidas gaseosas, se ha convertido en uno de los principales problemas de salud bucal en niños, adolescentes y adultos jóvenes, cuyo tratamiento deviene en desafío para los profesionales de la salud. La investigación se propuso evaluar el efecto erosivo exógeno de las bebidas gaseosas, sobre el tejido dentario mediante el proceso de termociclado in vitro, en el que se sometieron 50 premolares extraídos a la experiencia de exposición a una bebida gaseosa, bajo condiciones de experimentación, resultando una diferencia significativa entre el peso inicial pre termociclado en cada pieza y el peso final obtenido después del proceso, lo cual demuestra el efecto negativo del consumo de bebidas gaseosas. En ese mismo sentido, y como parte de esta investigación, se evaluó los efectos beneficiosos de los probióticos como la L-alanina como suplemento de las bacterias beneficiosas a la salud bucal como el Lactobalilos rhamnosus GG que logran detener el avance de bacterias patógenas y oportunistas como el Streptococcus mutans. Los resultados mostraron que a medida que aumenta la concentración del probiótico, mayor es la disminución del número de unidades formadoras de colonias y de las biopelículas de Streptococcus mutans. Además, la investigación aborda la percepción del riesgo en estudiantes, de ingestión de bebidas gaseosas en la erosión dentaria y los criterios que sobre el tema tienen sus profesores tutores(AU)
The high prevalence of erosive dental wear caused by the frequent ingestion of soft drinks has become one of the main oral health problems in children, adolescents and young adults, whose treatment becomes a challenge for health professionals. The research aimed to evaluate the exogenous erosive effect of soft drinks on dental tissue through the in vitro thermocycling process, in which 50 extracted premolars were subjected to the experience of exposure to a soft drink, under experimental conditions, resulting in a significant difference between the initial pre-thermocycling weight in each piece and the final weight obtained after the process, which demonstrates the negative effect of the consumption of soft drinks. In that same sense, and as part of this research, the beneficial effects of probiotics such as L-alanine were evaluated as a supplement for beneficial bacteria for oral health such as Lactobalilos rhamnosus GG, which manage to stop the advance of pathogenic and opportunistic bacteria such as Streptococcus mutans. The results showed that as the concentration of the probiotic increases, the decrease in the number of colony-forming units and biofilms of Streptococcus mutans is greater. In addition, the research addresses the perception of risk in students, of ingestion of soft drinks in dental erosion and the criteria that their tutor teachers have on the subject(AU)
Subject(s)
Humans , Male , Female , Adult , Middle Aged , Arginine , Streptococcus mutans , Biofilms , Lacticaseibacillus rhamnosus , Tooth Wear , Bacteria , Tooth Erosion , Carbonated Beverages , Oral Health , Probiotics , EatingABSTRACT
Many advancements have been done in the field of dentistry for resin composites applications. However, polymerization shrinkage stays a problem. Marginal gap and microleakage in between tooth cavity wall and restorative material is caused by forces of contraction, masticatory forces, polymerization shrinkage, poor adhesion, temperature variables, and inadequate moisture control. An impaired marginal seal resulting due to microleakage provides entry of oral fluids, ions, bacteria which causes recurrent caries, discoloration and hastening of marginal breakdown of restoration, hypersensitivity, pathology of pulp that would decrease the life of restoration. The purpose of restoring cavities by using nanohybrid and micro filled composite was to assess if it would eliminate or decrease microleakage in this in vitro study. We wanted to assess the effectiveness of nanohybrid and micro filled composites with regard to microleakage in class I cavity restoration.METHODSStandardized class I cavities were prepared over thirty teeth. The teeth samples were randomly distributed in to two groups based on composite used for restoration. Group A (n=15): Restored with nanohybrid composite followed by light curing. Group B (n =15): Restored with micro filled composite followed by light curing. The samples were stored in a 1% chloramine beta-hemihydrate solution for a day and then thermocycling procedure was performed. The samples were soaked in 2 % methylene blue for a day and sectioning of samples was done through the center of restoration using a diamond disk and analysed for methylene blue dye penetration with a stereomicroscope in 12X magnification. Scoring was done based on the criteria of a 0-4 scale.RESULTSChi square test was used for performing statistical analysis. No significant difference in the microleakage score between nanohybrid and micro filled composite was seen (p = 0.338).CONCLUSIONSIn this study both groups showed microleakage. However, nanohybrid composite resin showed better marginal adaptation of restoration as compared to micro filled composite resin.
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Abstract The present study was evaluated the effect of different light activation and thermocycling methods on the shear bond strength (SBS) and on the adhesive remnant index (ARI) of metal brackets bonded to feldspathic ceramic. Hundred metal brackets were bonded to 20 porcelain cylinders, divided into four groups (n=25) based on light activation and thermocycling processes. The cylinders were etched with 10% hydrofluoric acid for 60 s and coated with two layers of silane. The brackets were bonded with Transbond XT composite resin. Light activation in Groups 1 and 3 was performed during 3 s using the VALO Ortho Cordless appliance with irradiance 3,200 mW/cm2 and in Groups 2 and 4 for 40 s using Optilight Max appliance with irradiance 1,200 mW/cm². The samples were stored in deionized water at 37°C for 24 h and the samples from Groups 1 and 2 were submitted to the SBS test at a rate of 1 mm/min, whereas the samples from Groups 3 and 4 were submitted to 7,000 thermal cycles (5°/55°C) before to the SBS test. The data were assessed by two-way analysis of variance and by Tukey's test (a=0.05). No significant difference was observed between SBS means in the different light activation devices used. The samples subjected to thermocycling revealed lower SBS values (p≤0.05). There was predominance of score 0 for ARI in all groups. Therefore, the different light activation methods did not interfere in SBS, but thermocycling reduced SBS.
Resumo No presente estudo foi avaliado o efeito de diferentes métodos de fotoativação e ciclagem térmica na resistência da união ao cisalhamento (RUC) e no índice de remanescente adesivo (IRA) de braquetes metálicos colados à cerâmica feldspática. Cem braquetes metálicos foram colados em 20 cilindros de porcelana, divididos em 4 grupos (n=25) de acordo com o processo de fotoativação e ciclagem térmica. Os cilindros foram condicionados com ácido fluorídrico 10% por 60s e receberam 2 camadas de silano. Os braquetes foram colados com a resina composta Transbond XT. A fotoativação nos Grupos 1 e 3 foi realizada por 3 segundos usando o aparelho VALO Ortho Cordless com irradiância de 3200 mW/cm2 e nos Grupos 2 e 4 por 40 segundos utilizando o aparelho Optilight Max com irradiância de 1200 mW/cm². As amostras foram armazenadas em água deionizada a 37°C por 24 h, após as amostras dos grupos 1 e 2 foram submetidos ao teste de RUC, velocidade de 1 mm/min, e as amostras dos grupos 3 e 4 foram submetidas a 7.000 ciclos térmicos (5°/ 55°C) antes da RUC. Os dados foram submetidos à Análise de Variância dois fatores e ao teste de Tukey (a=0,05). Não foi encontrada diferença significativa entre as médias da RUC nos diferentes aparelhos de fotoativação. Quando submetidos à ciclagem térmica apresentaram menores valores de RUC (p≤0,05). O IRA mostrou predominância de escore 0 para todos os grupos. Conclui-se que os diferentes métodos de fotoativação não interferiram na RUC, porém a ciclagem térmica reduziu a RUC.
Subject(s)
Dental Bonding , Orthodontic Brackets , Surface Properties , Materials Testing , Resin Cements , Dental Cements , Shear Strength , Dental Porcelain , Dental Stress AnalysisABSTRACT
Objective@#To evaluate the effect of two commonly used zirconia primers on the bond strength and durability of zirconia ceramics. @*Methods@# Zirconia wafers with a diameter of 5 mm and a thickness of 2 mm were cut and prepared by CAD/CAM (51). After sintering, sandblasting, ultrasonic cleaning and drying, the zirconia wafers are divided into three groups according to the types of zirconia primer: group A, no primer group; group B, Z-Prime plus; and group C, Clearfil Ceramic Primer, with each set containing 17 samples. The surface morphology of zirconia was observed by scanning electron microscopy after applying the coating primer according to the operation specifications. Then, the microshear bonding specimens were made, and the bonding strength was tested after water storage for 3 days and 5 000 × thermocycling. @*Results@#The surface of zirconia ceramics was roughened by sandblasting. After Z-Prime plus coating, the primer did not completely cover the zirconia surface, which is island like. After coating with the Clearfil Ceramic Primer, the primer was completely covered on the surface of zirconia ceramics without exposure to zirconia. Energy spectrum analysis showed that the content of C, O, Si and P in the coating area was relatively high. After primer coating, the bonding strength between zirconia and resin cement was significantly higher than that of group A (20.6 ± 2.1)MPa, P < 0.05, while there was no significant difference in the immediate bonding strength between group B (33.2 ± 3.9)MPa and group C (30.7 ± 2.4)MPa (P > 0.05). After 5 000 × thermocycling, the bonding strength of group A was(4.1 ± 2.5)MPa, that of group B was (23.1 ± 2.3)MPa and that of group C was (28.9 ± 2.6)MPa. There were statistically significant differences among groups A, B and C. The aging adhesive strength of groups A and B was significantly reduced compared with the immediate adhesive strength (P < 0.05). Group C had the highest bonding strength after aging (28.9 ± 2.6) MPa, with no significant difference before and after aging (P > 0.05). After 5 000 × thermocycling aging, the percentage of bonding failure in the fracture mode of group A increased from 66% to 100% and that of group B increased from 16% to 53%. In group C, the percentage of bonding failure increased from 20% to 24%.@*Conclusion @# The zirconia primers on the surface of zirconia ceramics after sandblasting can enhance the bonding strength and durability of zirconia.
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@#This study compared the surface roughness of selected tooth coloured restorative materials that were polished according to manufacturers’ instructions and Sof-Lex. It also assessed the surface roughness of polished materials after thermocycling. Filtek Z350XT, Beautifil-Bulk Restorative and Cention N, were used in this study. A stainless steel mould (10mm diameter x 2mm height) was used to fabricate 75 cylindrical specimens: 15 Filtek Z350XT (FZ), 30 Beautifil-Bulk Restorative (BB) and 30 Cention N (CN). All 15 FZ specimens were polished with Sof-Lex. Fifteen BB and CN specimens were polished according to manufacturers’ instructions. The remaining fifteen BB and CN specimens were polished using Sof-Lex. All the specimens were subjected to thermocycling (1000 cycles). Surface roughness was assessed quantitatively with profilometry after specimen preparation (Mylar stage), polishing and thermocycling. Data were analysed using SPSS version 25.0 at α=0.05. When polished according to manufacturers’ instructions, BB had the lowest mean surface roughness (Ra) values (0.13±0.01μm) followed sequentially by CN (0.14±0.03μm) and FZ (0.15±0.02μm). The differences were not statistically significant. When polished with Sof-Lex, BB exhibited the smoothest surface (0.116±0.03μm) followed sequentially by and FZ (0.150±0.02μm) and CN (0.157±0.02μm). Thermocycling caused an increase in the Ra. The differences were statistically significant. All materials tested had Ra values below the threshold value of 0.2 µm at Mylar stage and after polishing with their recommended polishing system and Sof-Lex. Thermocycling produced rougher surfaces that did not exceed the threshold Ra value. Polishability was material dependent.
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Objective: This study evaluates the shear bond strength (SBS) and Vickers micro-hardness (VHN) of the orthodontic adhesive resin Transbond XT using thermocycled samples. The study also measures the degree of cure by poliwave light curing unit Valo. Materials and Methods: 135 brackets were bonded for the SBS test, and 90 disc-shaped orthodontic adhesive resins were prepared for the VHN test. The measurements were taken either immediately or after 500 or 10.0000 thermocycling. The SBS and VHN test data were statistically evaluated using a Two-way ANOVA and Tukey multiple comparison tests. The degree of conversion (DC) was measured by FTIR. Results: The 10-sec polymerized control group (57.08) and the 10.000 termocycled samples (55.96) had the highest VHN scores. On the other hand, the 3 second polymerized and the 10.000 termocycled samples (39.22) had the lowest VHN scores. There was no significant difference in the bracket SBS values between the termocycled and immediate groups. An evaluation of the bond failure surfaces revealed that the ARI scores did not differ between the immediate and the thermo-cycled groups according to the power modes. The FTIR results revealed that the lowest DC was seen in the 3 second light-cured sample. Conclusion: TransbondXT provided sufficient bond strength, microhardness and DC under in vitro bracket bonding conditions after 3 and 10 s of Poliwave LED curing. However, low mean values were seen in the groups that received Poliwave LED curing for only 3 s (AU)
Objetivo: Este estudo avalia a resistência ao cisalhamento (SBS) e a microdureza Vickers (VHN) da resina adesiva ortodôntica Transbond XT utilizando amostras termocicladas. O estudo também mede o grau de cura pela unidade de fotopolimerização Valo poliwave. Materiais e Métodos: 135 braquetes foram colados para o teste SBS e 90 discos de resina adesiva ortodôntica foram preparados para o teste VHN. As medições foram feitas imediatamente ou após 500 ou 10.000 ciclos de termociclagem. Os dados dos testes SBS e VHN foram avaliados estatisticamente usando ANOVA 2 fatores e teste de comparação múltipla de Tukey. O grau de conversão (DC) foi medido por FTIR. Resultados: O grupo controle polimerizado por 10segundos (57,08) ciclados por 10.000 ciclos (55,96) tiveram os valores VHN mais altos. Por outro lado, as amostras polimerizadas de 3 segundos e 10.000 ciclos (39,22) os valores de VHN mais baixos. Não houve diferença significativa nos valores de SBS do braquete entre os grupos termociclados e imediato. Uma avaliação das superfícies de falha de adesão revelou que os escores do ARI não diferiram entre os grupos imediato e termociclados de acordo com as densidades de potência. Os resultados do FTIR revelaram que o menor DC foi observado nas amostras fotopolimerizadas de 3 segundos. Conclusão: Transbond XT forneceu suficiente resistência de união, microdureza e DC sob condições de colagem de braquetes in vitro após 3 e 10 s de polimerização em LED Poliwave. No entanto, valores médios baixos foram observados nos grupos que receberam a cura do LED Poliwave por apenas 3 s (AU)
Subject(s)
Orthodontics , Spectroscopy, Fourier Transform Infrared , Shear Strength , Lasers, SemiconductorABSTRACT
Objectives: The objective of the present study is to evaluate the bond strength of: (a) Zirconia blocks (tribochemical treatment and zirconia primer) and resin blocks bonded using self-adhesive resin cement (phosphate monomer cement). (b) Zirconia blocks and resin blocks bonded using nonphosphate monomer cement. (c) Micro-tensile bond strength of zirconia and resin blocks, bonded with self-adhesive resin cement and nonphosphate monomer cement after thermocycling. Materials and Methods: Twenty zirconium-dioxide specimens (5 mm × 5.4 mm × 13 mm) were produced using a metal mold. Each zirconium block was duplicated in light-curing resin material specimen (5 mm × 5.4 mm × 13 mm) using a mold made of addition silicon impression material. A total of 40 specimens were made, of which 20 specimens were zirconia blocks and 20 were resin blocks, which would be bonded to each other using phosphate monomer-containing cement (Multilink [10 nos.]) and nonphosphate monomer-containing cement (RELY-X [10 nos.]). The specimens were then divided into two groups of n = 10 each. The surface of zirconium specimen of one group (Group 1) was treated with zirconia primer and bonded with phosphate monomer-containing cement, and the other groups (Group 2) were not treated with any surface conditioning and were bonded with a nonphosphate containing cement. The specimens in each group were further subdivided into two subgroups of n = 5 each as follows: Group 1-1A (subjected to thermocycling), 1B (nonthermocycled) and Group 2-2A (subjected to thermocycling), 2B (nonthermocycled). Then, they were subjected for testing of tensile bond strength under a universal testing machine. Results: Resin cement selection seems to be a more relevant factor in the bonding of zirconia. The phosphate monomer-containing cement has the better bond strength after thermocycling compared to the nonphosphate monomer group. Thermocycling reduced the bond strength of both the groups and a significant difference was seen in the bond strength of nonphosphate monomer cement group subjected to thermocycling compared to the nonthermocycled one. Tensile bond strength values were significantly affected by the luting agent system employed and by thermal aging. Hence, for long-term durability, luting of zirconia with a phosphate monomer-containing cement after the zirconia has been surface treated is preferable as their bond strength did not show much significant difference after being subjected to thermocycling, compared to the nonthermocycled group. Conclusion: Resin cement selection seem to be a more relevent factor in the bonding of zirconia thermocycling does affect adhesion to to zirconium oxide ceramics.
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The objective of this study was to compare the shear bonding strength of zirconia after cleaning the crown contaminated by saliva or blood and determine the effect of thermocycling. 180 specimens were embedded in acrylic resin. 20 Specimens in the positive control group were bonded with resin cement without contamination. 20 Specimens in the negative control group were washed with water for 20 seconds and then dried for 10 seconds. 120 Specimens contaminated by saliva or blood were cleaned by using three cleaning methods: 37% phosphoric acid gel, commercial cleanse, and 2.5% NaOCl. All samples were bonded with resin cement and divided into two subgroups: One was not aged, and the other was tested with 30,000 thermocycling. In both groups contamination by saliva and blood, no statistically significant difference was not found in control, groups cleansed by commercial cleanser and 2.5% NaOCl. When the groups cleansed with water and 37% phosphate gel were compared with the control, significantly low shear bond strength was shown. Thermocycling group showed statistically significantly low shear bond stress compared to the groups without thermocycling. When zirconia was contaminated by saliva or blood, its original shear bond strength could be obtained if it was cleaned with commercial cleanser or 2.5% NaOCl.
Subject(s)
Crowns , Methods , Resin Cements , Saliva , WaterABSTRACT
PURPOSE: The aim of this in vitro study was to investigate the fracture resistance under chewing simulation of implant-supported posterior restorations (crowns cemented to hybrid-abutments) made of different all-ceramic materials. MATERIALS AND METHODS: Monolithic zirconia (MZr) and monolithic lithium disilicate (MLD) crowns for mandibular first molar were fabricated using computer-aided design/computer-aided manufacturing technology and then cemented to zirconia hybrid-abutments (Ti-based). Each group was divided into two subgroups (n=10): (A) control group, crowns were subjected to single load to fracture; (B) test group, crowns underwent chewing simulation using multiple loads for 1.2 million cycles at 1.2 Hz with simultaneous thermocycling between 5℃ and 55℃. Data was statistically analyzed with one-way ANOVA and a Post-Hoc test. RESULTS: All tested crowns survived chewing simulation resulting in 100% survival rate. However, wear facets were observed on all the crowns at the occlusal contact point. Fracture load of monolithic lithium disilicate crowns was statistically significantly lower than that of monolithic zirconia crowns. Also, fracture load was significantly reduced in both of the all-ceramic materials after exposure to chewing simulation and thermocycling. Crowns of all test groups exhibited cohesive fracture within the monolithic crown structure only, and no abutment fractures or screw loosening were observed. CONCLUSION: When supported by implants, monolithic zirconia restorations cemented to hybrid abutments withstand masticatory forces. Also, fatigue loading accompanied by simultaneous thermocycling significantly reduces the strength of both of the all-ceramic materials. Moreover, further research is needed to define potentials, limits, and long-term serviceability of the materials and hybrid abutments.
Subject(s)
Bite Force , Crowns , Fatigue , In Vitro Techniques , Lithium , Mastication , Molar , Survival RateABSTRACT
Objective:To evaluate the effect of epigallocatechin-3-gallate (EGCG) and epigallocatechin-3-O-(3-O-methyl)-gallate (EGCG-3Me) on the anti-bacterial effect and the stability of intraradicular dentin-adhesive interface.Methods:EGCG and EGCG3Me with the concentration of 400 μg/ml were incorporated into Single Bond 2 (SB2) respectively to obtain 2 modified adhesives E-SB2 and E3-SB2.Confocal laser scanning microscopy(CLSM) and ultraviolet spectrophotometry were used to evaluate the anti-bacterial effect of the modified adhesives.Micro-Raman spectrum was used to test the degree of conversion (DC) of the adhesives.Push-out bond strength test was conducted to examine the immediate bond strength and the bond strength after themocycling.Results:E-SB2 and E3-SB2 both showed inhibiting effect on the proliferation of E.faecalis,while E3-SB2 performed stronger inhibiting effect.DC and the immediate push-out bond strength of SB2 were not decreased with the incorporation of EGCG or EGCG-3Me(P ＞ 0.05).E-SB2 and E3-SB2 showed significantly higher push-out bond strengths than that of SB2 (P ＜ 0.05) after themocycling.Conclusion:EGCG and EGCG-3Me modified adhesives have anti-bacterial effect and can enhance the stability of bonding between intraradicular dentin and adhesive,EGCG-3Me may have stronger anti-bacterial effect.
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Objective:To evaluate the effect of different shoulder width on the compressive strength of full-contour zirconia crowns.Methods:A computer aided design and computer aided manufacturing(CAD/CAM) system was used to prepare 24 full-contour zirconia crowns of the mandible first molar.1 mm occlusal thickness crowns with 4 shoulder width of knife-edge(group A),0.3 mm(group B),0.5 mm(group C) and 1.0 mm(group D) (n =6).The Co-Cr alloy PFM crowns made by the die of group C were used as the controls (n =6).All the full-contour zirconia crowns were bonded to the corresponding die using 3 M glass ionomer cement (GIC) and the compressive strength were measured by an universal testing machine.Based on the statistical analysis,crowns with the shoulder width of 0.5 mm were treated by the thermocycling test under cycling of 10000 times(group C1),20 000 times(group C2) and 30000 times (group C3) respectively(n =6).One-way ANOVA method was used for the statistical analysis.Results:The mean compressive strength(N) of group A,B,C,D and E was 3855.00 ± 305.47,2731.70 ± 261.80,3698.30 ± 276.87,3841.70 ± 544.88 and 2992.17 ± 168.41 respectively.The strength of group B and E were lower than that of group A,C and D(P ＜ 0.05),B vs E P ＞0.05.The compressive strength(N) of group C1,C2 and C3 was 3220.00 ± 504.38 (group C1),3148.33 ± 425.60(C2) and 2992.17 ±168.41 (C3) respectively (P＞0.05).Conclusion:For the full-contour zirconia crowns,both the knife-edge shoulder and the shoulder wider than 0.3 mm can meet the thermoclinical needs.The cycling times used in this study have no influences on the compressive strength.
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PURPOSE: The aim of this study was to investigate the effects of a titanium component for the zirconia abutment in the internal connection implant system on screw loosening under thermocycling conditions. MATERIALS AND METHODS: Internal connection titanium abutments and external connection zirconia abutments with titanium sockets were connected respectively to screw-shaped internal connection type titanium implants with 30 Ncm tightening. These implant-screw-abutment assemblies were divided into two groups of five specimens each; titanium abutments as control and zirconia abutments with titanium sockets as experimental group. The specimens were subjected to 2,000 thermocycles in water baths at 5℃ and 55℃, with 60 seconds of immersion at each temperature. The removal torque values (RTVs) of the abutment screws of the specimen were measured before and after thermocycling. RTVs pre- and post-thermocycling were investigated in statistics. RESULTS: There was not screw loosening identified by tactile and visual inspection in any of the specimens during or after thermocycling. The mean RTV difference for the control group and the experimental group were -1.34 ± 2.53 Ncm and -1.26 ± 2.06 Ncm, respectively. Statistical analysis using an independent t-test revealed that no significant differences were found in the mean RTV difference of the groups (P > 0.05). CONCLUSION: Within the limitations of this in vitro study, the titanium socket for the zirconia abutment did not show a significant effect on screw loosening under thermal stress compared to the titanium abutment in the internal connection implant.
Subject(s)
Baths , Immersion , In Vitro Techniques , Titanium , Torque , WaterABSTRACT
PURPOSE: To investigate the effect of reducing tooth preparation and ceramic thickness on fracture resistance of lithium disilicate crowns. MATERIALS AND METHODS: Specimen preparation included a standard complete crown preparation of a typodont mandibular left first molar with an occlusal reduction of 2 mm, proximal/axial wall reduction of 1.5 mm, and 1.0 mm deep chamfer (Group A). Another typodont mandibular first molar was prepared with less tooth reduction: 1 mm occlusal and proximal/axial wall reduction and 0.8 mm chamfer (Group B). Twenty crowns were milled from each preparation corresponding to control group (n=5) and conditioned group of simultaneous thermal and mechanical loading in aqueous environment (n=15). All crowns were then loaded until fracture to determine the fracture load. RESULTS: The mean (SD) fracture load values (in Newton) for Group A were 2340 (83) and 2149 (649), and for Group B, 1752 (134) and 1054 (249) without and with fatigue, respectively. Reducing tooth preparation thickness significantly decreased fracture load of the crowns at baseline and after fatigue application. After fatigue, the mean fracture load statistically significantly decreased (P .05) in Group A. CONCLUSION: Reducing the amount of tooth preparation by 0.5 mm on the occlusal and proximal/axial wall with a 0.8 mm chamfer significantly reduced fracture load of the restoration. Tooth reduction required for lithium disilicate crowns is a crucial factor for a long-term successful application of this all-ceramic system.
Subject(s)
Ceramics , Crowns , Fatigue , Lithium , Molar , Tooth Preparation , ToothABSTRACT
OBJECTIVES: To determine the combined effect of fatigue cyclic loading and thermocycling (CLTC) on the shear bond strength (SBS) of a resin cement to zirconia surfaces that were previously air-abraded with aluminum oxide (Al₂O₃) particles at different pressures. MATERIALS AND METHODS: Seventy-two cuboid zirconia specimens were prepared and randomly assigned to 3 groups according to the air-abrasion pressures (1, 2, and 2.8 bar), and each group was further divided into 2 groups depending on aging parameters (n = 12). Panavia F 2.0 was placed on pre-conditioned zirconia surfaces, and SBS testing was performed either after 24 hours or 10,000 fatigue cycles (cyclic loading) and 5,000 thermocycles. Non-contact profilometry was used to measure surface roughness. Failure modes were evaluated under optical and scanning electron microscopy. The data were analyzed using 2-way analysis of variance and χ² tests (α = 0.05). RESULTS: The 2.8 bar group showed significantly higher surface roughness compared to the 1 bar group (p < 0.05). The interaction between pressure and time/cycling was not significant on SBS, and pressure did not have a significant effect either. SBS was significantly higher (p = 0.006) for 24 hours storage compared to CLTC. The 2 bar-CLTC group presented significantly higher percentage of pre-test failure during fatigue compared to the other groups. Mixed-failure mode was more frequent than adhesive failure. CONCLUSIONS: CLTC significantly decreased the SBS values regardless of the air-abrasion pressure used.
Subject(s)
Adhesives , Aging , Aluminum Oxide , Fatigue , Microscopy, Electron, Scanning , Resin CementsABSTRACT
Introduction: Fracture of an acrylic resin complete denture base after aging, poses problem for patients, dentists and dental laboratory technicians. This study was performed to determine the effect of thermocycling on the flexural strength of a commercially available, heat-polymerized acrylic denture base material reinforced with glass fibers, carbon fibers, aramid fibers and high (HI) impact resins. Materials and Methods: Forty specimens were made of similar dimension from five groups of materials. Each group had eight specimens. A commercially available heat polymerized P.M.M.A denture base resin was selected as control and PMMA reinforced with glass, carbon, aramid fibres and HI impact resin were compared. All specimens were then subjected to thermocycling before testing. Flexural strength was evaluated with universal testing machine. The results were analyzed with Analysis of Variance (ANOVA) followed by Turkey HSD test. Results: All reinforced specimens and HI impact resins showed better flexural strength than the conventional acrylic resin after thermocycling. Specimens reinforced with glass fibers showed the highest flexural strength, followed by HI impact resin, carbon fibers and aramid fibers. After artificial aging, a significant improvement in the flexural strength of conventional acrylic resin was observed when it was reinforced with glass fibers. Conclusion: Within the limitations of this study, incorporation of 2% by weight of glass fibre in PMMA resin exhibited statistically significant maximum flexural strength followed by high impact resin, carbon, polyaramid reinforced P.M.M.A denture base resin. These can readily be used in the fabrication of dentures subjected to heavy masticatory loads.
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PURPOSE: The aim of this study was to investigate whether the application of nano-structured alumina coating to the surface of Y-TZP could enhance the bond strength with resin cement. MATERIALS AND METHODS: A total of 80 zirconia plates were prepared and divided into four groups. : 1) airborne particle abrasion treatment (A) : 2) Rocatec treatment after airborne particle abrasion (R) : 3) nano-structured alumina coating treatment after polishing (PC) and 4) nano-structured alumina coating after airborne particle abrasion (AC). Alumina coating was formed by the hydrolysis of aluminium nitride (AlN) powder and heat treatment at 900℃. Coating patterns were observed with FE-SEM. Resin block was bonded to treated zirconia ceramics using resin cement. The shear bond strengths were measured before and after thermocycling. RESULTS: The FE-SEM images show a dense and uniform nano-structured alumina coating structure, which enhances shear bond strength by increasing micro mechanical interlocking to resin cement. PC and AC groups showed higher shear bond strengths than A and R groups before and after thermocycling. A and R groups displayed significant drops in shear bond strength after thermocycling. However, PC and AC groups did not show any meaningful decreases in shear bond strength after thermocycling. CONCLUSION: Treatment of Y-TZP ceramics with nano-structured alumina coating could significantly increase their shear bond strength.
Subject(s)
Aluminum Oxide , Ceramics , Hot Temperature , Hydrolysis , Resin CementsABSTRACT
The objective of this study was to evaluate the effects of different light sources, thermocycling and silane on the bond strength of metallic brackets to ceramic. Cylinders of feldspathic ceramic were etched with 10% hydrofluoric acid for 60 s. Half of the cylinders (Groups 1 to 4) received two layers of silane. Metallic brackets were bonded to the cylinders using Transbond XT and divided into 8 groups (n=20), according to light source (Radii Plus LED - 40 s; Groups 1, 2, 5 and 6 and XL 2500 halogen light - 40 s; Groups 3, 4, 7 and 8) and experimental conditions with (Groups 2, 4, 6 and 8) without thermocycling (Groups 1, 3, 5 and 7). Shear bond testing was carried out after 24 h of deionized water storage (Groups 1, 3, 5 and 7) and thermocycling (Groups 2, 4, 6 and 8; 7,000 cycles - 5°/55 °C). Date were submitted to three-way ANOVA and Tukey's post hoc test (α=0.05). The Adhesive Remnamt Index (ARI) was evaluated at 8× magnification. The application of silane was effective in increasing the shear bond strength of the brackets to ceramic (p<0.05). Significant difference (p<0.05) on the bond strength was observed between light sources with or without thermocycling. The ARI showed a predominance of scores 0 for all groups, with an increase in scores 1, 2 and 3 for the silane groups. In conclusion, silane improved significantly the shear bond strength of the brackets to ceramic. The thermocycling and light sources influence on the bond strength.
Resumo O objetivo neste estudo foi avaliar o efeito de diferentes fontes de luz, termociclagem e silano na resistência de união de bráquetes metálicos a cerâmica feldspática. Cilindros de cerâmica feldspática foram condicionados com ácido fluorídrico a 10% por 60 s. Metade dos cilindros (Grupos 1 a 4) recebeu duas camadas de silano. Bráquetes metálicos foram colados aos cilindros usando Transbond XT (3M Unitek), formando 8 grupos (n=20), dependendo das fontes de luz usadas para fotoativação (Radii Plus LED - 40s; Grupos 1, 2, 5 e 6 e XL 2500 halógena - 40 s; Grupos 3, 4, 7 e 8), nas condições experimentais com (Grupos 2, 4, 6 e 8) e sem ciclagem térmica (Grupos 1, 3, 5 e 7). O ensaio de resistência ao cisalhamento foi realizado após armazenagem por 24 h em água deionizada (Grupos 1, 3, 5 e 7) ou armazenados e submetidos a ciclagem térmica (Grupos 2, 4, 6 e 8; 7.000 ciclos - 5° e 55° C). Os dados foram submetidos à Análise de Variância de três fatores e teste de Tukey (α=0,05). O Índice de Remanescente Adesivo (IRA) foi avaliado com aumento de 8×. O uso do silano foi efetivo no aumento da resistência de união ao cisalhamento de bráquetes à cerâmica. Diferença significante na resistência de união foi observada entre as fontes de luz, e com ou sem ciclagem térmica. O IRA mostrou predominância de escore 0 para todos os grupos, com aumento de escores 1, 2 e 3 para os grupos com silano. Em conclusão, a aplicação do silano melhorou significativamente a resistência de união ao cisalhamento de bráquete à cerâmica. A ciclagem térmica e as fontes de luz influenciaram a resistência da união.
Subject(s)
Ceramics , Metals , Shear Strength , Silanes/chemistryABSTRACT
El objetivo de este estudio fue el de evaluar el grado de microfiltración en dos sistemas de reconstrucción postendodóncica, valorando la penetración de un colorante a lo largo de las restauraciones realizadas con endopostes y cementos duales de resina. En este estudio se emplearon 30 dientes premolares unirradiculares extraídos a los que se les realizó tratamiento de conductos y almacenándolos en agua bidestilada a 37 ºC. Se distribuyeron los dientes en tres grupos de forma aleatoria, con diez dientes por cada grupo. La cementación de los postes se realizó en dos de los grupos, usando los sistemas RelyX Fiber post (3M ESPE dental products) y Parapost (Coltene-Whaledent). Las muestras fueron sometidas al proceso de termociclado y posterior inmersión en azul de metileno por siete días a 36 ºC. Posteriormente se diafanizaron las muestras y fueron analizadas bajo microscopio, obteniendo los valores de penetración en milímetros. Los resultados mostraron que los dientes tratados con el sistema Parapost presentaron menor microfiltración. El grupo control mostró el mayor índice de microfiltración. El análisis estadístico con la prueba de Donett mostró diferencia estadísticamente significativa entre los sistemas Parapost y RelyX. Conclusión: Se demostró que el sistema de reconstrucción Parapost (Coltene-Whaledent), el cual tiene una técnica de grabado ácido, reportó menores valores de microfiltración, siendo los resultados estadísticamente significativos con respecto a los obtenidos con el sistema de reconstrucción RelyX (3M ESPE dental products).
The aim of the present study was to assess the degree of microleakage observed when using two different post-endodontic reconstruction systems; this was achieved assessing penetration of a dye along restorations performed with endodontic posts and dual-cure resin cements. For the present study, 30 extracted, single rooted premolars were used. Root canal treatment was performed on the teeth which were later stored in bi-distilled water at 37 ºC. Teeth were randomly allotted to three groups, all groups were comprised of 10 teeth. In two groups, post cementation was performed using the systems RelyX Fiber Post (3M ESPE dental products) and Parapost (Coltene-Whaledent). Samples were subjected to thermo-cycling and later immersed in methylene blue for seven days at 36 ºC. After this, samples were subjected to a diaphanization process and were then analyzed under a microscope; penetration in millimeters was thus obtained. Results revealed that teeth treated with Parapost system exhibited lesser microleakage. Control group experienced the greater amounts of microleakage. Statistical analysis conducted with Donett test showed statistically significant difference between Parapost and RelyX systems. Conclusion: Parapost reconstruction system (Coltene-Whaledent) with acid-etch technique exhibited lower microleakage values. Results were statistically significant when compared to those obtained with the RelyX reconstruction system (3M ESPE dental products).
ABSTRACT
Abstracts: Background: To compare the microhardness and solubility of temporary restorative materials after thermocycling. Objective is to evaluate and compare the solubility of temporary restorative materials after storage in water and to evaluate and compare micro hardness of temporary restorative materials after thermocycling. Methodology: Forty specimens will be prepared for the study. Specimens are prepared according to following four groups.(n=10). Group I – Cavit, Group II - MD Temp, Group III-Coltosol, Group IV – TMP- RS. All the temporary restorative material are manipulated according to manufacturer’s instructions in the stainless steel moulds. All the samples are measured by weight. They are stored in distilled water for 7 days and again they are measured by weight after 7 days. The change in weight is evaluated. All the samples are thermocycled at 4 & 56 degree celsius with a dwell time of 60 seconds for 100 times. After thermocycling micro hardness is calculated by Vickers hardness test of all samples. Results: The study gives highly significant result with p value less than 0.001 of both solubility and micro hardness difference as detailed below. The least solubility is with Cavit G with value 0.011 followed by Coltosol F (0.039), TMP-RS(0.054) and MD Temp(0.122). The least change in micro hardness is with Cavit-G(13.48) followed by Coltosol F(15.54), MD Temp(18.07) and TMP-RS(20.41). All values are compared using one way ANOVA (p<0.001 highly significant). Conclusion: Within the limitations of study, Cavit-G has least solubility after storage in water and highest microhardness after thermocycling among four different temporary restorative materials.
ABSTRACT
PURPOSE: The purpose of this study was to find out the effect of immediate dentin sealing (IDS) on bond strength of ceramic restoration under various thermocycling periods with DBA (dentin bonding agent system). MATERIALS AND METHODS: Fifty freshly extracted human mandibular third molars were divided into 5 groups (1 control and 4 experimental groups) of 10 teeth. We removed enamel layer of sound teeth and embedded them which will proceed to be IDS, using All Bond II. A thermocycling was applied to experimental groups for 1, 2, 7, 14 days respectively and was not applied to control group. IPS Empress II for ceramic was acid-etched with ceramic etchant (9.5% HF) and silane was applied. Each ceramic disc was bonded to specimens with Duo-link, dual curable resin cement by means of light curing for 100 seconds. After the cementation procedures, shear bond strength measurement and SEM analysis of the fractured surface were done. The data were analyzed with a one-way ANOVA and Tukey multiple comparison test (alpha=.05). RESULTS: There were no statistically significant differences between 4 experimental groups and control group, however the mean value started to decrease in group 7d, and group 14d showed the lowest mean bond strength in all groups. Also, group 7d and 14d showed distinct exposed dentin and collapsed hybrid layer was observed in SEM analysis. CONCLUSION: In the present study, it can be concluded that ceramic restorations like a laminate veneer restoration should be bonded using resin cement within one week after IDS procedure.