Evaluation of the Effect of Various Beverages and Food Materials on the Color Stability of Provisional Materials: An In Vitro Study.

Aim This study aims to evaluate the color stability of four provisional materials: polymethyl methacrylate (DPI® Self-Cure), 10-ethoxylated bisphenol A dimethacrylate (Oratemp® C&B), bis-acryl composite resin (Systemp® C&B, Ivoclar Vivadent), and bis-acryl composite (Systemp® C&B, Ivoclar Vivadent) combined with light-cure composite (Fusion Flo® LC). Materials and methods A total of 40 specimens were meticulously crafted from modeling wax into discs, each precisely 2 mm thick and 20 mm in diameter. Four provisional materials were packed into molds, yielding 10 specimens for each material group. After mixing and polymerization, the specimens were trimmed and polished. Reflectance spectrophotometers were used for initial color assessments based on the CIELAB color space system. Staining solutions, including coffee, Tata Green Tea, Pepsi, and turmeric, were prepared to mimic dietary agents. Artificial saliva, replicating oral conditions, was formulated and sterilized. The specimens were then immersed in various solutions for 15 days at 37 °C. Color measurements were taken on days 2 and 15 using the same spectrophotometer, calculating color differences (ΔE) from changes in L*, a*, and b* values. Results DPI Self-Cure (polymethyl methacrylate) was found to be the most color-stable temporary restorative material, followed by Vivadent (bis-acryl composite resin), Oratemp (10-ethoxylated bisphenol A dimethacrylate), and Fusion Flo (light-cure composite). Fusion Flo exhibited the highest color change by the 15th day. Coffee and green tea demonstrated the greatest potential for causing color changes in the provisional restorative materials. Conclusion DPI Self-Cure exhibited the highest color stability among the provisional materials, with Vivadent and Oratemp following closely behind. Green tea and coffee were the most potent staining agents, while Pepsi and turmeric induced lesser color changes.

Physical and structural characterization of bis-acryl composite resin.

During the preparation of fixed prosthesis (including individual bridges and crowns) it is important to select the materials that have the best features and properties to predict a successful clinical treatment. The objective of this study was to determine if the chemical and structural characteristics could cause to increase the fracture resistance, we used four bis-acryl resins Luxatemp, Protemp, Structur and Telio. Three-points bending by Flexural test were performed in ten bars and they were carried out to compare with Anova test. In addition, the bis-acryl resins were analyzed by scanning electron microscopy, to analyze microstructure and morphology and the molecular structure were performed by Infrared Spectroscopy through Attenuated Total Reflectance. A higher flexural strength was found in Luxatemp and Structur with, no significant differences between this study groups. Regarding Protemp and Telio, these study groups showed a lower flexural strength when were compared with Luxatemp and Structur. These results corroborate SEM and ATR analysis because Luxatemp sample showed a regular size particle on the surface and chemically presents a long cross-linkage polymer chain. The presence of CO3, SiO2 and N-H groups as a fillers particle interacting with OH groups cause a higher flexural strength compared with another groups.

Evaluating the color stability of temporary crowns fabricated by 3-dimensional printing and manual methods.

This in vitro study aimed to compare the color stability of temporary crowns fabricated by 3-dimensional (3D) printing with that of crowns fabricated with 2 manual methods. An impression was made of a prepared central incisor, from which 90 dies were fabricated. The dies were randomly assigned to 3 groups (n = 30) based on crown fabrication method: 3D printing, automix bis-acryl resin, or powder-and-liquid polymethyl methacrylate. All specimens were immersed in a coffee, soft drink, or distilled water solution for 1 week (n = 10 per subgroup). Color change was measured using a spectrophotometer and the International Commission on Illumination's CIE L*a*b* method, and the values were converted to the National Bureau of Standards (NBS) index for assessment and comparison. When color change was assessed according to fabrication method, the highest (mean [SD]) ΔE* value was reported for the automix specimens (3.39 [2.86]), and the lowest was recorded for the powder-and-liquid specimens (2.05 [2.33]) (P < 0.05; Kruskal-Wallis test). The difference between ΔE* values of the 3D printing group (2.46 [1.75]) and the powder-and-liquid group was not statistically significant. When color change was assessed according to the immersion solution, the coffee solution showed a significantly higher (mean [SD]) ΔE* value (5.04 [2.67]) than the soft drink (1.43 [0.92]) and distilled water (3.41 [7.93]) solutions (P < 0.05; Kruskal-Wallis test). The color changes associated with the 3 methods were statistically equal in terms of the NBS index ranges, most frequently falling in the range of very minor to acceptable change. The powder-and-liquid method seems to be most suitable for fabricating temporary prostheses for long-term use.

Polytetrafluoroethylene tape spacer for direct splinted teeth-supported provisional restoration: A dental technique.

Provisional restoration is essential for function, esthetics, occlusion, and tissue health. However, when multiple teeth are involved, making a direct splinted provisional restoration could be challenging due to the combined undercuts between the prepared teeth. This article describes a dental technique using polytetrafluoroethylene (PTFE) tape as a spacer to fabricate a splinted provisional restoration for multiple prepared teeth. The PTFE tape spacer will compensate for discrepancies in the path of insertion between prepared teeth, thus facilitating the removal of the direct splinted provisional restoration intact.

Comparative Evaluation of Flexural Strength of Four Different Types of Provisional Restoration Materials: An In Vitro Pilot Study.

With provisional restorations, properties such as flexural strength play a key role in maintaining the abutment teeth in position over the interim period until the final restorations are placed. This study aimed to evaluate and compare the flexural strength of four commonly used provisional resin materials. Ten identical 25 × 2 × 2 mm specimens were made from four different groups of provisional resin material, namely 1: SR Ivocron (Ivoclar Vivadent) cold-polymerized poly-methyl methacrylate (PMMA), 2: S Ivocron (Ivoclar Vivadent) heat-polymerized PMMA, 3: Protemp (3M Germany-ESPE) auto-polymerized bis-acryl composite, and 4: Revotek LC (GC Corp, Tokyo) light-polymerized urethane dimethacrylate resin. The mean values of the flexural strength of each group were calculated and the data were analyzed using one-way ANOVA and Tukey post hoc tests. The mean values (MPa) were as follows: for cold-polymerized PMMA, it was 125.90 MPa; for heat-polymerized PMMA, it was 140.00 MPa, with auto-polymerized bis-acryl composite 133.00 MPa; and for light-polymerized urethane dimethacrylate resin, it was 80.84 MPa. Thus, the highest flexural strength was recorded with heat-polymerized PMMA and the lowest flexural strength with light-polymerized urethane dimethacrylate resin, which was significantly low. The study did not detect a significant difference in the flexural strengths of cold PMMA, hot PMMA, and auto bis-acryl composite.

Comparison of Fracture Resistance between Implant-supported Bis-acryl Interim 3-unit FDPs Using Six Different Strengthening Mechanisms: An In Vitro Study.

AIM: To investigate six different strengthening mechanisms for three-unit implant-supported provisional restorations. MATERIALS AND METHODS: Six techniques of provisional fixed prostheses (PFP) reinforcement were investigated and were assigned to different groups (n = 10): group (ZP) zirconia powder, group (SK8) silk thread wrapped as a figure-of-8 pattern around middle third of abutment, group (RC8) size 00 retraction cord wrapped as a figure-of-8 pattern around middle third of abutment, group (RF8) Resin impregnated glass fiber ribbon wrapped as a figure-of-8 pattern around abutment, group (KV8) Kevlar 29 cord wrapped as a figure-of-8 pattern around middle third of abutment, group (KV) Kevlar 29 strands incorporated in resin mix. Compared against unenforced bis-acryl as control group (CL). Seventy Metal Dies were 3D printed having Soft Tissue Gingiva Mask. Using a custom-made silicone Index, 70 PFP were fabricated (10 of each group) and were cemented to their corresponding metal dies using zinc polycarboxylate cement. All specimens were thermal cycled for 1000 cycles using order of 20 seconds at 55°C and 20 seconds at 5°C with 10 seconds transport. Fracture resistance test was done using universal testing machine. All specimens were loaded to failure. Data were collected, tabulated and statistically analyzed. RESULTS: Kolmogorov-Smirnov normality test showed no significant difference between data in each group. So, data are normally distributed in each group. Descriptive statistics showed higher mean values of CL group (780.8 ± 164) followed by RF8 group (614.2 ± 158.2), followed by RC8 group (550.2 ± 339.2), followed by KV8 group (442.1 ± 198.4), followed by KV group (403.9 ± 306), followed by SK8 group (175.9 ± 90.8), and finally ZP group (136.5 ± 135.7). One-way ANOVA revealed significant difference between the tested groups (p = 0.036). CONCLUSION: Bis-acryl provisional restorations had better mean fracture resistance values than all other strengthening mechanisms. Bis-acryl provisional restorations did not gain more strength by any of the added materials. One-way ANOVA revealed significant difference between all tested groups. CLINICAL SIGNIFICANCE: Provisional restorations over implant should be strong enough to serve for the long period of bone and tissue healing. Current materials alone cannot survive for long. It serves as temporization between steps of fixed restorations construction. How to cite this article: Rayyan M, Sayed M, Hujeiry AM et al. Comparison of Fracture Resistance between Implant-supported Bis-acryl Interim 3-unit FDPs Using Six Different Strengthening Mechanisms: An In Vitro Study. J Contemp Dent Pract 2023;24(11):840-846.

Color and surface gloss stability of bis-acryl and resin composite after exposure to cigarette smoke / Estabilidade de cor e brilho superficial de resinas compostas e bisacrílicas após exposição por fumaça de cigarro

Objective: To evaluate color and surface gloss stability of bis-acryl resins and resin composites, submitted to artificial staining with cigarette smoke. Material and Methods: Specimens of each material were prepared (n=15). Two resin composites (GrandioSO [RCG], Filtek Supreme [RCZ]) and five bis-acryl resins (Luxatemp Star [BisLUX], Protemp4 [BisPRO], Structor3 [BisSTR], Visalys Temp [BisVIS] and Yprov [BisYPR]) were tested. Initial color was assessed using a spectrophotometer and surface gloss with a glossmeter. Samples were submitted to smoke exposure (10 cigarettes under 8 minutes per cycle). After 3 and 6 cycles, color and gloss were reassessed. Final readings were performed after brush prophylaxis. Data were analyzed using two-way repeated ANOVA and Tukey's test (p<0.05). Results: Differences and interaction of factors (p<0.01) were detected for both color and gloss readings. Resin composites were the least affected by aging, with gloss reduction after prophylaxis. Differences were detected among bis-acryl resins, with better results for BisLUX and BisPRO. BisPRO and BisSTR, showed reduction in gloss after 60 cigarettes, while BisYPR gloss decreased at all evaluated periods. Conclusion: Resin composites are less susceptible to changes after smoke exposure, while bis-acryl resins results are brand-dependent. Prophylaxis negatively influenced the surface gloss of most of the tested materials (AU)

Objetivo: Avaliar a estabilidade de cor e brilho superficial de resinas compostas e bisacrílicas, submetidos ao manchamento artificial por fumaça de cigarro. Material e Métodos: Foram preparados espécimes de cada material (n=15). Duas resinas compostas (GrandioSO [RCG], Filtek Supreme [RCZ]) e cinco resinas bisacrílicas (Luxatemp Star [BisLUX], Protemp4 [BisPRO], Structor3 [BisSTR], Visalys Temp [BisVIS] e Yprov [BisYPR]) foram testados. A cor inicial foi avaliada usando um espectrofotômetro e o brilho de superfície com um medidor de brilho. As amostras foram submetidas à exposição de fumaça de cigarro (10 cigarros com até 8 minutos por ciclo). Após 3 e 6 ciclos, a cor e o brilho foram reavaliados. As leituras finais foram realizadas após a profilaxia escova de robinson. Os dados foram analisados usando de medidas repetidas e teste de Tukey (p<0,05). Resultados: Foram detectadas diferenças e interação de fatores (p<0,01) tanto para leituras de cor quanto para leituras de brilho. As resinas compostas foram as menos afetados pelo envelhecimento, com redução do brilho após a profilaxia. Foram detectadas diferenças entre as resinas bisacrílicas, com melhores resultados para BisLUX e BisPRO. BisPRO e BisSTR, mostraram redução de brilho após 60 cigarros, enquanto que o brilho da BisYPR diminuiu em todos os períodos avaliados. Conclusão: As resinas compostas são as menos suscetíveis a mudanças após a exposição à fumaça, enquanto os resultados das resinas bisacrílicas são dependentes da marca. A profilaxia influenciou negativamente o brilho de superfície da maioria dos materiais testados.(AU)

Effect of Cartridge Storage Time and Ambient Laboratory Conditions on the Stability of Mechanical Properties of Bis-Acryl Interim Resin Materials.

PURPOSE: To investigate the stability of mechanical properties during the entire shelf life of chemically-activated bis-acryl interim resin materials stored at ambient laboratory conditions. MATERIALS AND METHODS: Four bis-acryl interim resin materials with no explicit recommendation for refrigerator storage were selected (Luxatemp Plus, Visalys Temp, Structur 3, Structur Premium). Following cartridge storage at ambient laboratory conditions in 6-month intervals, 30 specimens (2.0 × 2.0 × 25.0 mm3 ) were prepared in each case and stored in distilled water (37.0 ± 1.0 °C) with 3 different water storage times (2 hours, 24 hours, 7 days). Flexural strength, modulus of elasticity, modulus of toughness, and elastic recovery were determined (3-point bend test). Data were subjected to a three-way multivariate analysis of variance (MANOVA) to determine overall significance, followed by a series of separate one-way ANOVAs after data were split, using Tukey and Games-Howell post hoc tests to identify significant differences between groups (α = 0.05). RESULTS: While Luxatemp Plus showed no significant decrease for all mechanical properties during the investigated shelf life of 21 months (p > 0.05), Visalys Temp exhibited a continuous decline of the corresponding values (p < 0.05), irrespective of the water storage time. Structur 3 and Structur Premium properties remained almost unchanged during the first 6 months of the examination period. Subsequently, a progressive decrease was observed for flexural strength and modulus of elasticity, while most modulus of toughness and elastic recovery results revealed little alteration. CONCLUSION: Depending on the bis-acryl interim resin material, mechanical properties appeared to be susceptible to continuous degradation processes during cartridge storage at ambient conditions, especially towards the end of the material shelf life. For some materials, the chemical stabilization and recommended storage conditions should be revised by the manufacturers to prevent premature aging during shelf life.

Comparison of Marginal Accuracy of Interim Restoration Fabricated from Self-cure Composite and Autopolymerizing Acrylic Resin: An In Vitro Study.

BACKGROUND AND OBJECTIVES: One of the important steps toward achieving a successful fixed partial denture treatment is the fabrication of interim restorations with good marginal adaptation. Poor marginal adaptation of the interim restorations will allow ingress of fluids and microorganisms between the restorations and may lead to caries and pulpitis. The objective of this study was to evaluate and compare the marginal accuracy of interim restorations made from two polymethyl methacrylate (PMMA) and two bis-acryl materials. MATERIALS AND METHODS: An in vitro method was used to replicate a clinical procedure in which the interim crown was made using a direct technique. A maxillary first molar typodont tooth was prepared to receive a full cast crown restoration having 1 mm chamfer and a taper of 5°, and then the prepared artificial tooth was cast into a cobalt chromium metal die. Wax patterns were prepared on the metal die using type 2 inlay wax for full metal crowns. The impression of the die along with the wax pattern was made with a putty-type polyvinyl siloxane, and this impression was used as a mold for making interim restorations. Two PMMA and two bis-acryl provisional crown materials were distributed as follows: Group A: Unifast Trad (GC Dental), Group B: DPI self-cure tooth molding material, Group C: Structur 2 QM (VOCO), and Group D: Cool Temp Natural (Coltene/Whaledent). A total of 60 interim restorations from all the four materials were fabricated (15 interim restorations from each material). The marginal discrepancy of the interim restoration was determined by measuring the space between the margin of the interim restoration and the finish line of the metal die at four vertical reference lines previously marked at the midpoint of the metal die finish line at the buccal, palatal, mesial, and distal surfaces of the die. The marginal gaps were visualized at ×45 magnification using a stereomicroscope and interpreted using ProgRes image capture software. RESULTS: The mean marginal discrepancy calculated in PMMA materials was 269 µm for DPI and 205 µm for Unifast Trad, and the mean marginal gap for the bis-acryl material was 171 µm for Cool Temp and 140 µm for Structur 2 QM. INTERPRETATION AND CONCLUSION: Comparison of marginal accuracy showed that bis-acryl provisional crown material showed better marginal accuracy than PMMA provisional crown material. Among the materials tested, Structur 2 QM showed the best marginal accuracy, and the least marginal accuracy was shown by DPI.

Color stability of a bis-acryl composite resin subjected to polishing, thermocycling, intercalated baths, and immersion in different beverages.

OBJECTIVE: To evaluate the color of a bis-acryl resin after polishing, aging, and colorants. MATERIALS AND METHODS: From the 140 disks obtained, 35 were not polished (NP), 35 were polished with 3-µm (3P), 35 with 3- and 1-µm (1P), and 35 with 3-, 1-, and 0.5-µm sized particles (05P). Five disks of each group were thermocycled for 20, 100, and 200 cycles. Sixty disks were thermocycled and kept in beverages (tea, wine, and coffee) after four cycles. Sixty disks were immersed in the beverages for 24 hours, a week, and a month. The coordinates L*a*b* were measured and the color differences were analyzed by ANOVA. The lightness, chroma, and hue differences were evaluated by repeated measures ANOVA. Comparisons were made with Tukey's test (α = 0.05). RESULTS: Similar behaviors were observed between 3P and 05P groups (1.53 and 1.95ΔE00 ) (P < .05). The NP group submitted to 200 cycles showed the biggest color differences (3.02) (P = .003). The greatest color differences were observed in the NP group submitted to immersion in coffee (8.30) and wine (7.93) (P < .05). CONCLUSIONS: The polished surfaces were the least stained. Coffee and wine provided the greatest color changes, both for baths and immersions. CLINICAL SIGNIFICANCE: Polishing of provisional surfaces restorations made of bis-acrylic resin is essential to minimize staining caused by aging and use of colorants, regardless of the particle size present in the polishing paste. The contact with coffee and red wine should be avoided, especially for clinical times greater than 1 week.

Influence of experimental staining on the color stability of indirect computer-aided design/computer-aided manufacturing dental provisional materials.

OBJECTIVE: This study presents a comparative analysis of the color stability of computer-aided design/computer-aided manufacturing (CAD/CAM)-fabricated provisional restorations with those of conventional restorations. MATERIALS AND METHODS: Three different provisional restorative materials (Systemp C&B, 3M Protemp 4, and Telio CAD) were inspected for their color stability using four solutions (Pepsi, coffee, tea, and distilled water). All samples used were fabricated using A1 shade by following the manufacturer's instructions. Color assessment was performed using CIELAB system and a colorimeter. After baseline color measurement, color assessments were done weekly after immersion in specified solutions. Triplicate readings were taken for every sample and the mean value of the color coordinates (L*), (a*), and (b*) were recorded at baseline, week 1, week 2, week 3, and week 4. The data within different groups were compared statistically using analysis of variance (α = 0.05). RESULTS: Overall, the highest color stability was found in CAD/CAM material, followed by Protemp and SystempC&B. It was also observed that the maximum color variation was observed in case of coffee, followed by tea and Pepsi. CONCLUSIONS: CAD/CAM provisional material (Telio CAD) showed better color stability compared to conventional materials (Protemp 3M ESPE and SystempC&B Ivoclar Vivadent). CAD/CAM provisional materials are recommended for long-term temporization procedures. This is attributed to the prepolymerization, higher monomer conversion, and minimal preparation errors in CAD/CAM materials.

Injectable technique for direct provisional restoration.

OBJECTIVE: New technique describes an alternative treatment modality of making direct provisional restoration. CLINICAL CONSIDERATIONS: A preoperative wax-up should be fabricated, followed by fabrication of a transparent polyvinyl siloxane (VPS) matrix in a clear plastic prefabricated tray with retentive holes. After the tray is separated from the model, two additional holes will be made through the tray and the VPS for injecting and venting of the temporary resin. After the teeth are prepared and the separating medium applied to them, the resin should be injected into the entrance hole using the provided auto-mix cartilage tip. The flow of the resin around the preparation can be observed through the clear mold and once the resin starts to extrude from the exit hole. It is necessary to block the exit hole with a finger while continuing to inject. This will increase the pressure inside the mold and improve marginal adaptation. Before complete polymerization, the matrix is removed. The provisional restorations are removed from the matrix and contoured, adjusted, and polished. CONCLUSION: This technique will help the clinicians to enhance the quality of the provisional restorations, to prevent entrapment of bubbles, improve marginal precision and prevent seating error. CLINICAL SIGNIFICANCE: This study described a novel technique for constructing a direct provisional restoration by injecting bis-acryl temporary resin into a matrix that is already seated over the prepared tooth.

Effect of delayed time, surface treatment, and repair material on shear bond strength of repaired bis-acryl composite resin

PURPOSE: The aim of this study was to evaluate the effect of delayed time, surface treatment, and repair materials on repair of bisacryl composite resin through comparison of shear bond strength and to evaluate the utility of bis-acryl composite resin repair using polymethyl methacrylate resin. MATERIALS AND METHODS: A total of 90 bis-acryl composite resin specimens were fabricated and classified into 9 test groups, each of 10 pieces according to delayed time, surface treatment and repair material. The shear bond strength of each specimen was measured using a universal testing machine immediately after fabrication and analyzed using a statistical analysis program (IBM SPSS statistics 20). After the shear bond strength measurement, the fracture surface of the specimen was observed. RESULTS: The highest shear bond strength (17.54 ± 3.14 MPa) was observed in the experimental group bonded immediately with a light-curing flowable composite resin using a bonding agent. CONCLUSION: When repairing bis-acryl composite resin, it is necessary to consider whether to remake according to the delayed time. For effective repair, it is desirable to consider appropriate materials and surface treatment methods according to the site or purpose of use.

Influência da técnica de polimento na rugosidade superficial e perfilometria de materiais à base de resina bisacrílica / Influence of the polishing technique on the roughness and profile of bis-acryl-based materials

Problematização. É de grande importância a escolha da técnica e do material a serem utilizados para a confecção das restaurações provisórias. O material deve apresentar espessura suficiente e resistência para suportar as cargas mastigatórias sem sofrer deformação ou fratura, bem como, sua superfície deve apresentar um bom acabamento e polimento, reduzindo assim o acúmulo de biofilme, facilitando a higienização pelo paciente. Objetivo. Investigar qual o melhor protocolo de polimento para as diferentes resinas bisacrílicas com a intenção de obter uma superfície lisa. Material e métodos. Um total de 104 amostras foram confeccionadas (15mm de comp. x 5mm de largura x 4mm de altura) e foram divididos em três fatores de estudo: material (Protemp 4, Structur 3, Dencor, Z350XT), polimento (discos Sof-Lex Pop On e Sof-Lex Spiral) e período (inicial, pós polimento, pós escovação). Foram confeccionadas 13 amostras por grupo de material, sendo que em cada etapa foi retirado uma amostra aleatoriamente com a finalidade de submeter à análise de microscopia eletrônica de varredura (MEV), totalizando 24 amostras para serem submetidas a este teste, e assim, resultando em 80 amostras para serem escovadas, e em 10 amostras por grupo para análise estatística (n=10). Em todas as amostras foram realizadas leituras (µm) da rugosidade de superfície (Ra) em todos os períodos, ou seja, logo após serem confeccionadas, após o polimento e após escovação, através do rugosímetro (Hommel tester). Ao final, as 80 amostras foram submetidas a leitura no perfilômetro, para análise do desgaste superficial. Os resultados para a rugosidade foram submetidos a ANOVA a três critérios seguido pelo teste de Tukey (α = 0,05). E para o desgaste superficial os resultados foram submetidos a ANOVA a dois critérios seguido pelo teste de Tukey (α = 0,05). Resultados. A resina bisacrílica Protemp 4 mostrou maiores valores de rugosidade superficial (Ra) quando polidos com os discos Sof-Lex Spiral (0,284 µm), quando comparado ao polimento com discos Sof-Lex Pop On (0,075 µm), após a escovação houve aumento da rugosidade superficial para ambos os tipos de polimentos, tanto os discos Sof-Lex Spiral (0,375 µm) quanto para o polimento com os discos Sof-Lex Pop On (0,359 µm), mas não houve diferença estatística significativa (p>0,05). Para os resultados de desgaste superficial, não houve diferença estatística entre os grupos: da resina bisacrílica Protemp 4 com polimento Sof-Lex Pop On (13,95 µm), e com o polimento com os discos Sof-Lex Spiral (14,91µm) e o grupo da resina composta Z350XT polidos com os dois sistemas de polimento ­ Sof-Lex Pop On e Sof- Lex Spiral (12,61µm, 12,70 µm respectivamente). A resina bisacrílica Structur 3 mostrou menores valores de rugosidade de superfície quando polidos com os discos Sof-Lex Pop On (0,113 µm) em comparação ao polimento com os discos Sof-Lex Spiral (0,223 µm). Para os resultados de desgaste superficial, não houve diferença entre os grupos da resina bisacrílica Structur 3, porem os valores tanto para o grupo polido com os discos Sof-Lex Pop On (15,77 µm) e o grupo polido com os discos Sof-Lex Spiral (15,40 µm) foram bem próximos aos valores do grupo da resina bisacrílica Protemp 4 e ao grupo da resina composta Z350XT, com diferença estatística. As duas resinas bisacrílicas testadas, a Protemp 4 e a Structur 3 nos dois sistemas de polimentos mostraram melhores valores de rugosidade superficial (Ra) e menores valores de desgaste superficial que a resina acrílica Dencor. Conclusão. Através do polimento é possível melhorar a rugosidade superficial dos materiais resinosos, entretanto, a técnica, o operador, os materiais a serem polidos e o sistema de acabamento e polimento estão diretamente correlacionados. Para este estudo, o sistema que obteve os melhores resultados foi o dos discos Sof-Lex Pop On, e a resina bisacrílica que apresentou o menor número de Ra foi a resina bisacrílica Structur 3. Para o desgaste superficial a resina bisacrílica Structur 3 mostrou valores maiores comparados aos resultados do grupo da resina bisacrílica Protemp 4, esta, por sua vez, mostrou valores de desgaste superficial próximos ao do grupo da resina composta Z350 XT.(AU)

Statement of the problem. The choice of technique and material for making provisional restorations is important. The material must have enough strength to withstand the masticatory loads without suffering deformation or fracture and its surface must have good finishing and polishing to reduce biofilm accumulation. Objective. The aim of this study was to investigate what is the best polishing protocol for different bis-acryl materials with the intention to obtain a smooth surface. Materials and methods. A total of 104 samples were made (15mm long x 5mm wide x 4mm high) and were divided into three study factors: material (Protemp 4, Structur 3, Dencor, Z350XT), polishing (Sof-Lex Pop On and Sof-Lex Spiral discs) and period (initial, postpolishing, post-brushing). Thirteen samples were made per material group, and at each step, a sample was randomly taken for the purpose of submitting to scanning electron microscopy (SEM) analysis, totaling 24 samples to be submitted to this test, and thus, resulting in 80 samples to be brushed, and 10 samples per group for statistical analysis (n = 10). In all samples, surface roughness readings (µm) were performed at all periods, that is, after they were made, after polishing and after brushing through the rugosimeter (Hommel tester). At the end, the 80 samples were read in a profilometer for analysis of surface wear. The results for the roughness were submitted to ANOVA for three criteria followed by the Tukey`s test (α = 0.05), and for the surface wear test, the results were submitted to ANOVA for two criteria followed by the Tukey`s test (α = 0.05). Results. Protemp 4 bis-acryl showed higher values of surface roughness when polished with Sof-Lex Spiral discs (0.284 µm) when compared to Sof-Lex Pop On discs polishing (0.075 µm). After brushing, there was an increase of surface roughness for both types of polishing. Sof-Lex Spiral discs (0.375 µm) and Sof-Lex Pop On discs (0.359 µm), but with no significant differences (p>0.05). For the surface wear results, there was no statistical difference between the groups: Protemp 4 bis-acryl resin with Sof-Lex Pop On polishing (13.95 µm) and polishing with the Sof-Lex Spiral discs (14.91 µm ) and the Z350XT composite resin group polished with the two polishing systems - Sof-Lex Pop On and Sof-Lex Spiral (12.61µm, 12.70µm, respectively). Structur 3 bis-acryl resin showed lower surface roughness results when polished with Sof-Lex Pop On discs (0.113 µm) compared to Sof-Lex Spiral discs (0.223 µm). For the surface wear results, there was no difference between the groups of the Structur 3 bis-acryl resin, but the values for both the polished group with Sof-Lex Pop On discs (15.77µm) and the group polished with the Sof-Lex discs Spiral (15.40 µm) were very close to the values of the group of the Protemp 4 bis-acryl resin and the Z350XT composite resin group, with statistical difference. The two tested bis-acryl resins, the Protemp 4 and Structur 3 in the two polishing systems, showed better surface roughness values (Ra) and lower surface wear values than the Dencor acrylic resin. Dencor acrylic resin group showed the highest values of surface roughness at all times. However, after polishing and brushing, the surface roughness presented lower values, when compared to Ra initial values, but this material showed the highest surface wear values (31.21 µm).The resin composite group Z350XT which polishing procedure was Sof-Lex Pop On discs showed lower values (0.039 µm). There were no statistically significant differences in surface roughness at all periods and the surface roughness increased after brushing, followed by lower values also for surface wear (12.61 µm). Conclusion. By polishing it is possible to improve the surface roughness of the resinous materials, however, the technique, the operator, the materials to be polished and the finishing and polishing system are directly correlated. For the present study, the system that obtained the best results was the Sof-Lex Pop On discs, and the bis-acryl resin that presented the lowest Ra number was the Structur 3 bis-acryl resin. For surface wear, the Structur 3 bis-acryl resin showed higher values compared to the results of the Protemp 4 bis-acryl resin group, which, in turn, showed surface wear values close to that of the Z350 XT composite resin group.(AU)

Comparative Evaluation of Flexural Strength of Provisional Crown and Bridge Materials-An Invitro Study.

INTRODUCTION: Provisional restorations serve a key role as a functional and esthetic try-in for the design of the final prosthesis. During selection of materials for this restoration, clinicians must consider physical properties, ease of handling, cost and patient satisfaction and approval. AIM: To evaluate and compare the flexural strength of provisional crown and bridge materials available commercially. MATERIALS AND METHODS: This in-vitro study was done to compare the flexural strength of six temporary crown and bridge materials available commercially at 24 hours, 8 days and after repair. Three poly methyl methacrylate based materials (DPI, SC10 and Trulon) and three bis-acrylic based composite resins (Protemp, Cooltemp and Luxatemp) were selected. A total of 72 specimens of dimensions 64mm×10mm×2.5mm were prepared from these materials (12 from each material) and divided into two groups (n=36). Specimens were stored in artificial saliva and were fractured after 24 hours and 8 days using Universal Testing Machine. The fractured samples from the 8 days study were then subjected to repair. A uniform space of 2mm and a 450 bevel was maintained for all the repaired samples for better distribution of forces. Flexural strength of these repaired samples was recorded using the same machine. RESULTs were recorded and statistically analysed by one-way Anova and Post hoc tests. RESULT: RESULTs revealed that there was decrease in flexural strength for all the materials tested from 24 hours to 8 days, though flexural strength between poly methyl methacrylate and bis-acrylic resins was similar at 24 hours and 8 days time interval. A substantial decrease was noticed in the strength of bis-acrylic composite resins after repair. CONCLUSION: From the current study it can be suggested that though there is decrease in flexural strength for all the materials from 24 hours to 8 days, both can be used to fabricate the provisional restorations. However, in the event of a fracture of a bis-acrylic provisional restoration, it may be more advantageous to make a new provisional restoration than to repair the fractured one.

Chemical compatibility of interim material and bonding agent on shear bond strength

PURPOSE: The purpose of this study is finding proper bonding agents to be used when adding bis-acryl composite provisional materials. MATERIALS AND METHODS: Three bonding agents with different chemical compositions were included in this study. Forty disk shaped specimens of bis-acryl composite provisional material were prepared and divided into 4 groups according to the bonding agents. Control group didn't have bonding agent. Through the Teflon mould with 4.0 mm diameter hole with 4.0 mm thickness the same bis-acryl composite provisional material was added on the disks after the surface of each specimen was treated with designated bonding agent according to the manufacturer's instructions. Shear bond test was performed and the fractured surfaces were inspected with a microscope. One-way analysis of variance was conducted and the result was further analysed with Turkey post hoc test at the significance level of 0.05. RESULTS: The highest strength was acquired from the specimens bonded with chemical cure system and it was statistically significant (P < 0.05). This group showed 100% cohesive failures. The lowest bonding strength was recorded from the specimens used conventional light cure bonding agent, and this group's result was similar with the control group. The group used a light cure bonding agent claiming improved compatibility revealed significantly higher bond strength to the traditional light cure bonding agent group in a statistically significant way (P = 0.043). CONCLUSION: According to the bonding agent used the shear bond strength was significantly affected. Therefore the choice of proper bonding agent is important when hiring a bonding agent to add bis-acryl composite provisional materials.

Effect of light-curing, pressure, oxygen inhibition, and heat on shear bond strength between bis-acryl provisional restoration and bis-acryl repair materials.

PURPOSE: This study aimed to discover a way to increase the bond strength between bis-acryl resins, using a comparison of the shear bond strengths attained from bis-acryl resins treated with light curing, pressure, oxygen inhibition, and heat. MATERIALS AND METHODS: Self-cured bis-acryl resin was used as both a base material and as a repair material. Seventy specimens were distributed into seven groups according to treatment methods: pressure - stored in a pressure cooker at 0.2 Mpa; oxygen inhibition- applied an oxygen inhibitor around the repaired material,; heat treatment - performed heat treatment in a dry oven at 60℃, 100℃, or 140℃. The shear bond strength was measured with a universal testing machine, and the shear bond strength (MPa) was calculated from the peak load of failure. A comparison of the bond strength between the repaired specimens was conducted using one-way ANOVA and Tukey multiple comparison tests (α=.05). RESULTS: There were no statistically significant differences in the shear bond strength between the control group and the light curing, pressure, and oxygen inhibition groups. However, the heat treatment groups showed statistically higher bond strengths than the groups treated without heat, and the groups treated at a higher temperature resulted in higher bond strengths. Statistically significant differences were seen between groups after different degrees of heat treatment, except in groups heated at 100℃ and 140℃. CONCLUSION: Strong bonding can be achieved between a bis-acryl base and bis-acryl repair material after heat treatment.

Effect of light-curing, pressure, oxygen inhibition, and heat on shear bond strength between bis-acryl provisional restoration and bis-acryl repair materials

PURPOSE: This study aimed to discover a way to increase the bond strength between bis-acryl resins, using a comparison of the shear bond strengths attained from bis-acryl resins treated with light curing, pressure, oxygen inhibition, and heat. MATERIALS AND METHODS: Self-cured bis-acryl resin was used as both a base material and as a repair material. Seventy specimens were distributed into seven groups according to treatment methods: pressure - stored in a pressure cooker at 0.2 Mpa; oxygen inhibition- applied an oxygen inhibitor around the repaired material,; heat treatment - performed heat treatment in a dry oven at 60degrees C, 100degrees C, or 140degrees C. The shear bond strength was measured with a universal testing machine, and the shear bond strength (MPa) was calculated from the peak load of failure. A comparison of the bond strength between the repaired specimens was conducted using one-way ANOVA and Tukey multiple comparison tests (alpha=.05). RESULTS: There were no statistically significant differences in the shear bond strength between the control group and the light curing, pressure, and oxygen inhibition groups. However, the heat treatment groups showed statistically higher bond strengths than the groups treated without heat, and the groups treated at a higher temperature resulted in higher bond strengths. Statistically significant differences were seen between groups after different degrees of heat treatment, except in groups heated at 100degrees C and 140degrees C. CONCLUSION: Strong bonding can be achieved between a bis-acryl base and bis-acryl repair material after heat treatment.

The effect of glass and polyethylene fiber reinforcement on flexural strength of provisional restorative resins: an in vitro study.

The aim is to evaluate and compare the flexural strength of different provisional restorative materials reinforced with glass and polyethylene fibers. A total of 90 samples were prepared and divided into three groups based on the type of fiber reinforcement, unidirectional S-glass (Splint-It) and ultra-molecular weight polyethylene (Ribbond). Unreinforced samples served as control group. Again each group was subdivided into three subgroups based on type of provisional restorative resins, heats cure polymethyl methacrylate, self-cure poly methyl methacrylate and self-cure bis-acryl composite. Samples were loaded in a universal testing machine until fracture occurs. The mean flexural strengths (MPa) were subjected to the one-way ANOVA, followed by the Tukey-HSD test at a significance level of 0.001. The result shows all the fiber reinforced samples possessed greater strength than the control samples. In control samples, the heat cure poly methyl methacrylate resin (72.74 ± 2.28 MPa) had the greatest flexural strength, followed by self-cure bis-acryl composite (67.05 ± 2.35 MPa) and self-cure poly methyl methacrylate resin (52.88 ± 1.90 MPa). In both heat and self-cure poly methyl methacrylate resin, the polyethylene fiber reinforcement (96.00 ± 2.63 MPa, 86.17 ± 1.92 MPa) provides the greatest strength than glass fiber reinforcement (92.68 ± 1.58 MPa, 76.40 ± 2.11 MPa). In self-cure bis-acryl composite, the glass fiber (105.95 ± 3.07 MPa) shows better reinforcement than polyethylene fiber (99.41 ± 1.74 MPa).The fibers reinforcement increases the flexural strength of provisional restorative resins.