Autopolymerizing Acrylic Resin Research Articles

Accuracy of different materials used in impressions for fixed partial dentures

Background: There are several elastic impression materials available for dental use. The present study evaluated accuracy of different materials used in impressions for fixed partial dentures.Materials & Methods: A master model of partially edentulous mandibular left hemi-arch segment was used. Custom trays were prepared with auto-polymerizing acrylic resin and impressions were taken using alginate and elastomeric materials and stone casts were formed. For the silicones, impression techniques were compared. Results: The mean discrepancies between the prepared tooth edges in the master model and in the stone casts in group I was 0.38 mm, in group II was 0.20 mm, in group III was 0.15 mm and in group IV was 0.34 mm. The difference was significant (P

Comparison of shear bond strength of CAD/CAM and conventional heat-polymerized acrylic resin denture bases to auto-polymerized and heat-polymerized acrylic resins after aging

BackgroundThe aim of this study was to investigate the shear bond strength of CAD/CAM and conventional heat polymerized acrylic resin denture bases bonded to self-cured and heat-cured acrylic resins after aging. Material and MethodsA total of 40 cubic specimens were fabricated from conventional heat-polymerized and CAD/CAM denture base resins. Denture base resin specimens in each group were divided into two subgroups (n=10) in which they were bonded to either a heat-cured (HC) or a self-cured (SC) reline resin. Subsequently, the specimens were subjected to thermocycling. Then the shear bond strength (SBS) of specimens was measured using the universal testing machine. After testing, modes of failure were examined using light microscopy. The results were submitted to statistical analysis. ResultsMann-Whitney test showed that in each group of denture base materials, specimens bonded to HC reline resin had significantly higher SBS than those bonded to SC reline resin (P<0.001). Conventional denture base bonded to HC resin exhibited the highest value of SBS. There was no statistically significant differences between the SBS of HC reline resin bonded to conventional and CAD/CAM with regards to SBS (P=0.218). However, the SBS of SC reline resin was significantly higher when bonded to CAD/CAM compared to conventional denture base resin (P<0.001). ConclusionsHeat-cured reline resin showed higher shear bond strength to both CAD/CAM and conventional heat-polymerized denture resin in comparison to self-cured reline resin. Although there was no difference between the bond strength of heat-cured reline resin to CAD/CAM and conventional denture base, self-cured reline material produced stronger bond with CAD/CAM denture base. Key words:CAD/CAM, shear bond strength, reline, denture base resin.

An In Vitro Trial to Estimate the Retention Ability of Luting Agents Utilized with Dental Implant-Supported Prosthesis.

Aim:The trial's goal was to assess the retentiveness of specially formulated implant cement besides comparing it to dental cements that are widely utilized by means of implant systems.Materials and Procedures:Twenty implant analogs were implanted in auto-polymerizing acrylic resin blocks and bonded to titanium abutments. Fifty uniform copings were waxed and cast unswervingly onto the abutment. (1) Resin-bonded zinc oxide eugenol cement, (2) purposefully designed implant cement, (3) zinc phosphate cement, (4) zinc polycarboxylate cement, and (5) glass ionomer cement were the cements used. Following cementation, each sample was pulled out by utilizing a widespread testing machine, and the stresses necessary to confiscate the crowns were recorded. The ANOVA and Bonferroni tests were used to examine the mean values and standard deviations of cement failure loads.Results:Zinc polycarboxylate cement had the peak mean cement failure load, followed by glass ionomer cement. Zinc phosphate cement had the next highest mean cement failure load, followed by resin-bonded zinc oxide eugenol cement. The mean cement failure load for Premier implant cement was the lowest. The difference in mean cement failure loads across the groups was statistically significant (P < 0.001).Conclusion:The findings do not imply that one type of cement is superior to another, but they do present a ranking directive of cements based on their capacity to maintain the prosthesis and facilitate retrievability.

Comparative Evaluation of Shear Bond Strength of Bioactive Restorative Material, Zirconia Reinforced Glass Ionomer Cement and Conventional Glass Ionomer Cement to the Dentinal Surface of Primary Molars: an in vitro Study.

Statement of the Problem: The success of dental restorations depends mainly on its ability to bond to dental structures and resist the multitude of forces acting on it within the oral cavity.Purpose: Therefore, the aim of this study was to evaluate the shear bond strength (SBS) of three different glass ionomer based restorative materials.Materials and Method: In this in vitro analytical study, 30 intact primary molars were sectioned buccolingually to obtain 60 sections. These sections were embedded in auto polymerizing acrylic resin and polished to obtain a flat dentin surface. Restoration cylinders were built on the dentin surface with the help of a Teflon template called bonding jig. Each group (n= 20) was restored as group A with conventional glass ionomer cement (GIC) (GC Fuji Gold Label Type 9), group B with Bioactive restorative material (ACTIVATM KIDS BioACTIVE Restorative material), and group C with Zirconia reinforced glass ionomer cement (Zirconomer). Following restoration, SBS testing was performed using Universal Testing Machine. The data obtained were statistically analyzed using One way ANOVA test and post hoc Tukey test (p= 0.05).Results: The SBS values were significantly greater in the ACTIVA KIDS group as compared to the other two groups (p< 0.05). There was no significant difference in the SBS values between group B and group C (p> 0.05).Conclusion: The SBS of the ACTIVA KIDS to primary teeth dentin was the highest as compared to Zirconomer and conventional GIC. Therefore ACTIVA KIDS may protect primary teeth against recurrent caries and failure of the restoration.

Effect of multiple firings on the shear bond strength of presintered cobalt-chromium alloy and veneering ceramic

Statement of problemHow multiple firing cycles may affect the oxide layer and, consequently, the shear bond strength of metal-ceramic restorations is unclear. PurposeThe purpose of this in vitro study was to determine the effect of multiple firings on the shear bond strength of porcelain to cobalt-chromium (Co-Cr) alloy. Material and methodsForty cylinders (Ø6.8×9 mm) of a representative presintered Co-Cr alloy (Ceramill Sintron) were prepared with computer-aided design and computer-aided manufacturing (CAD-CAM) technology. After airborne-particle abrasion and polishing, the specimens were ultrasonically cleaned of surface contaminants. A circular surface (Ø4×2 mm) was veneered on each specimen with porcelain (VM13) after 3 firings (wash opaque, opaque, and dentin). The specimens were then randomly divided into 4 groups (n=10). The normal group underwent 3 firings. The other groups underwent an additional porcelain firing: the one-plus firing group underwent 4 firings, the two-plus firing group underwent 5 firings, and the three-plus firing group underwent 6 firings. Next, the specimens were mounted in autopolymerized acrylic resin and tested in a universal testing machine and loaded at a crosshead speed of 0.5 mm/min at the metal-ceramic interface until fracture occurred. The average shear bond strength (MPa) was calculated by dividing the maximum fracture force (N) by the bonded surface of the specimens (mm2). The fracture patterns were observed microscopically and classified as adhesive, cohesive, or mixed. One-way ANOVA was used to determine differences between groups (α=.05). ResultsNo significant differences were found among the shear bond strengths of specimens after 3, 4, 5, and 6 porcelain firings (P>.05). The mean bond strength of all groups ranged from 30 to 34 MPa. The fracture pattern of all specimens was mixed, indicating that multiple firings had no significant effect on the failure pattern. ConclusionsMultiple porcelain firings under controlled conditions had no significant effect on the fracture pattern or shear bond strength of porcelain to a presintered Co-Cr alloy.

3D-Printed vs. Heat-Polymerizing and Autopolymerizing Denture Base Acrylic Resins.

The aim of this work was to investigate the effect of two post-curing methods on the mechanical properties of a 3D-printed denture base material. Additionally, to compare the mechanical properties of that 3D-printed material with those of conventional autopolymerizing and a heat-cured denture base material. A resin for 3D-printing denture base (Imprimo®), a heat-polymerizing acrylic resin (Paladon® 65), and an autopolymerizing acrylic resin (Palapress®) were investigated. Flexural strength, elastic modulus, fracture toughness, work of fracture, water sorption, and water solubility were evaluated. The 3D-printed test specimens were post-cured using two different units (Imprimo Cure® and Form Cure®). The tests were carried out after both dry and 30 days water storage. Data were collected and statistically analyzed. Resin type had a significant effect on the flexural strength, elastic modulus, fracture toughness, and work of fracture (p < 0.001). The flexural strength and elastic modulus for the heat-cured polymer were significantly the highest among all investigated groups regardless of the storage condition (p < 0.001). The fracture toughness and work of fracture of the 3D-printed material were significantly the lowest (p < 0.001). The heat-cured polymer had the lowest significant water solubility (p < 0.001). The post-curing method had an impact on the flexural strength of the investigated 3D-printed denture base material. The flexural strength, elastic modulus, fracture toughness, work of fracture of the 3D-printed material were inferior to those of the heat-cured one. Increased post-curing temperature may enhance the flexural properties of resin monomers used for 3D-printing dental appliances.

Marginal Fit of Temporary Restorations Fabricated by the Conventional Chairside Method, 3D Printing, and Milling.

Objectives: This study aimed to compare the marginal fit of temporary restorations fabricated by the conventional chairside method, 3D printing, and milling. Materials and Methods: In this in vitro, experimental study, 14 temporary restorations were conventionally fabricated over an implant abutment and analog that had been mounted in a phantom model at the site of canine tooth, using auto-polymerizing acrylic resin and putty index. In digital manufacturing, the original model was scanned, and the final restoration was designed. Fourteen temporary restorations were milled out of polymethyl methacrylate (PMMA) blocks, and 14 others were printed by a 3D printer. Temporary crowns were placed on the abutment, and images were obtained from specific areas under a stereomicroscope at x100 magnification to measure the amount of marginal gap. Data were analyzed using one-way ANOVA and Tukey’s test (α=0.05). Results: The mean marginal gap values for the temporary crowns in the 3D printing, milling, and chairside groups were 91.40, 75.28 and 51.23 µm, respectively. The crowns that were conventionally fabricated chairside exhibited the lowest marginal gap, and the difference in this respect was significant among the three groups (P<0.05). Conclusion: Temporary crowns fabricated by the chairside method showed significantly smaller marginal gap; however, the marginal gap of all three groups was within the clinically acceptable range.

Characterization of occlusal splint materials: CAD-CAM versus conventional resins

AimThe aim of this in vitro study was to assess the mechanical properties of five commercially available subtractive computer-aided design and computer-aided manufacturing (CAD-CAM) milled splint materials, as well as to compare them with conventional heat-polymerized and autopolymerizing resins used in the construction of conventional splints. Material and methodsFive CAD-CAM milled (ProArt CAD Splint, Therapon Transpa, Temp Premium Flexible Transpa, Cast, and Aqua), one autopolymerizing (Palapress), and one heat-polymerized (Paladon 65) resin materials were evaluated. Flexural strength, E-modulus, Vickers hardness, fracture toughness, fracture work, water sorption, and water solubility were measured. Samples were evaluated after dry and water storage for 30 days at 37 °C. Data were collected and statistically analyzed. ResultsUnder both storage circumstances, the flexural strength values of Paladon 65, Therapon Transpa, Temp Premium Flexible Transpa, and Aqua were statistically non-significant (P=0.055). The polycarbonate-based CAD-CAM material Temp Premium Flexible Transpa had the highest statistically significant values of the fracture toughness and fracture work (P<0.001). Moreover, it exhibited the lowest percentages of water sorption and water solubility among the investigated materials (P<0.001). All of the CAD-CAM materials exhibited dry elastic moduli greater than Palapress and lower than Paladon 65. One of the CAD-CAM materials, Cast, had the highest dry Vickers hardness value, which was non-significant when compared to Therapon Transpa (P=0.762). ConclusionCAD-CAM polycarbonate-based splint materials exhibit higher fracture toughness and fracture work as well as lower water sorption and solubility than polymethyl methacrylate-based ones. The mechanical characteristics of the assessed CAD-CAM milled splint materials were not typically superior to those of the conventional heat-polymerized resin. However, some of them outperformed the autopolymerizing acrylic resin in terms of flexural strength, surface microhardness, water sorption, and water solubility.

Assessment of Marginal Integrity and Color Stability of Provisional Restoration Fabricated from Different Autopolymerizing Acrylic Resins - A Comparative Study.

Aim:The present study is aimed to assess the marginal integrity and color stability of provisional restorations fabricated from different autopolymerizing acrylic resins.Materials and Methods:Totally, 60 provisional crowns were fabricated. A mandibular first molar artificial typodont was mounted on a base of dental stone. The mandibular first molar which was mounted was prepared for full cast crown, using the tooth preparation standard principles with shoulder finish line of 1 mm and taper 6°. There were 20 samples in each acrylic resin group: Group I: Polyvinyl-ethyl methacrylate resin, Group II: Autopolymerizing bis-acrylic material, and Group III: Polymethyl methacrylate (PMMA) autopolymerizing resin. Crowns were verified for marginal adaptation using stereomicroscope at a ×40. The color stability was measured using spectrophotometer poststaining period.Results:Autopolymerizing bis-acrylic material group showed minimum mean vertical marginal discrepancy (128.68 ± 18.036 μm) followed by PMMA autopolymerizing resin group (147.49 ± 20.128 μm) and polyvinyl-ethyl methacrylate resin group (172.89 ± 22.118 μm). Analysis of variance demonstrated a statistically significant difference between different autopolymerizing acrylic resins. The color change values did not show any significant difference between the groups on numerous comparisons between different autopolymerizing acrylic resin groups. A statistically significant difference was seen between Groups I and II, Groups I and III, and Groups II and III (P < 0.05).Conclusion:This study concluded that the autopolymerizing bis-acrylic material demonstrated significantly improved marginal integrity when compared to PMMA autopolymerizing resin and polyvinyl-ethyl methacrylate resin.

Effects of conventional and herbal irrigants on microhardness and flexural strength of root canal dentin: An in vitro study.

Aim:The aim of this in vitro study was to compare the effects of herbal irrigants with conventional irrigants on microhardness and flexural strength of root dentin.Materials and Methods:Sixty extracted permanent maxillary canines were selected. Decoronated roots were sectioned longitudinally into buccal and lingual segments to get 120 specimens. These were embedded in auto polymerizing acrylic resin and further grounded with fine emery papers under distilled water. Of these, 100 root segments without any defects were selected, further divided into four test groups and a control group according to the irrigants used (n = 20). Group 1: 2.5% Sodium hypochlorite, Group 2: Miswak stick extract, Group 3: Cashew leaves extract. Group 4: Mango leaves extract and Group 5: Normal saline (control). All specimens were treated with 5 ml of each irrigant for 10 minutes and rinsed immediately. Dentin microhardness was measured with a Vickers indenter, and the flexural strength test was done using a universal testing machine. The data were analyzed using one-way ANOVA and the intergroup comparison by student t-test.Results:The experimental groups showed a significant reduction in microhardness values when compared with the control group. Intragroup comparison among experimental groups, herbal irrigants showed the least reduction in microhardness values at cervical, middle, and apical thirds. When compared to the control group, the flexural strength values decreased significantly with experimental groups.Conclusion:Within the limitation of this study, it was concluded that herbal irrigants were least detrimental to root dentin microhardness when compared with conventional irrigant. But the flexural strength was equally reduced by both conventional and herbal irrigants.

Delayed Infection of an Autopolymerising Acrylic Resin Implanted for Orbital Floor Reconstruction

Delayed Infection of an Autopolymerising Acrylic Resin Implanted for Orbital Floor Reconstruction

An Alternative Incorporation Technique for Minimizing Complications in Attachment-Retained Implant Mandibular Overdentures: Technical Report.

The present technical report aimed to display an alternative incorporation method for ball/stud attachments in mandibular implant overdentures (MIO) to prevent or minimize metal housing debonding and attachment malpositioning. Precoating of metal housings with auto-polymerizing acrylic resin (AAR) and fabrication of straight AAR bars onto metal housings for optimal parallelism were used as new techniques. The glossy flat surfaces of metal housings (matrices) were sandblasted and precoated with a thin layer of AAR in the laboratory. Straight acrylic resin bars (3 cm long and 3 mm in diameter) were obtained and attached to these flat metal housing surfaces using a surveyor. The metal housings carrying the AAR bars were then placed intraorally onto ball/stud attachments, accurately positioned parallel to each other, and perpendicular to the long axes of implants and bound to the MIO with AAR.

The Effect of Different Beverage Solutions on the Hardness of Different Acrylic Denture Teeth

Aims: To determine the effect of different beverage solutions on the hardness of different acrylic denture teeth which are commercially available. Materials and Methods: Sixty samples were prepared from three brands of artificial teeth in this study. The posterior teeth of each brand were placed in auto polymerizing acrylic resin and the occlusal surfaces were ground flat, then immersed in distilled water (control), Pepsi, coffee and tea solutions for 30 days and then the hardness were tested using Vickers microhardness tester. Results: The RMH denture teeth materials showed the highest hardness than other denture teeth materials. Pepsi was more effective than tea and coffee in reducing the hardness of different acrylic teeth materials. Conclusions: Pepsi reduced the hardness of different acrylic teeth materials during the 30 days immersion. The hardness of RMH denture teeth materials was less affective by the different beverage solutions.

Effect of smear layer removal agents on the microhardness and roughness of radicular dentin

PurposeTo evaluate the effect of phytic acid (IP6) on the surface roughness and microhardness of human root canal dentin and compare it to other smear layer removal agents. Materials and methodsFifty extracted human maxillary incisors were sectioned longitudinally into a total of 100 specimens followed by embedding in auto-polymerizing acrylic resin. The specimens were polished and then randomly divided into five groups (n = 20) according to the test solution used to condition root canal dentin: 17% ethylenediaminetetraacetic acid (EDTA); 10% citric acid (CA); 1% IP6; 37% phosphoric acid (PA); or distilled water (control group). Each specimen was treated with a total volume of 1 ml of each solution for 1 min with agitation. Each group was then divided into two subgroups of 10 specimens each. The specimens of the first subgroup were used to determine microhardness, using Vickers hardness tester, and the specimens of the second subgroup were used to measure surface roughness, using a confocal laser scanning microscope. The results were analyzed statistically using one-way ANOVA and Tukey tests, α = 0.05. ResultsAll the tested groups exhibited microhardness and surface roughness values that were statistically significantly different when compared with the control group (P < 0.05). The microhardness value obtained with IP6 was significantly lower when compared to EDTA, CA, and the control group, whereas its roughness value was significantly higher compared to the aforementioned groups. However, there was no significant difference between IP6 and PA (P > 0.05). ConclusionsIP6 and PA showed the lowest microhardness and the highest surface roughness values.

In vitro shear bond strength of 2 resin cements to zirconia and lithium disilicate: An in vitro study

Statement of problemThere is little evidence on how the multiple layers of zirconia (ZrO2) or glazed material will affect the shear bond strength (SBS) of different resin cements. PurposeThe purpose of this in vitro study was to compare the SBS of 2 resin cements with the different layers of a monolithic polychromatic ZrO2 ceramic, both glazed and nonglazed, and a lithium disilicate (LDS) ceramic. Material and methodsOne hundred and sixty-eight composite resin cylinders and 48 monolithic polychromic ZrO2 plates were prepared. Twenty-four were milled and sintered, and 24 were milled and sintered and had a glaze cycle applied with no liquid glaze. These plates and 12 LDS plates were mounted in autopolymerized acrylic resin. Bonding surfaces were polished, airborne-particle abraded, and cleaned ultrasonically. The different layers (cubic, hybrid, and tetragonal) of the ZrO2 plates were identified and marked. The plates were assigned to 2 cement groups: a self-adhesive, autopolymerized resin cement, and a dual-polymerizing, adhesive resin cement (DPRC). Bonding surfaces were cleaned and treated according to the cement manufacturer’s instructions. Three composite resin cylinders were luted to the ZrO2 plates at the appropriate layer, and 2 cylinders were luted to each LDS plate. The specimens were stored in a moist environment for 24 hours at 37 °C. The SBS test was performed with a universal testing machine. Visual inspections of the debonded surfaces were compared under magnification. The data were analyzed with a 2-way ANOVA and a subsequent Student t test (α=.05). ResultsThe 2-way ANOVA found no difference among luting agent and LDS and ZrO2. The SBSs of the nonglazed tetragonal and cubic layer to the ZrO2 were higher than to the surface exposed to a glazing cycle (P=.001). The bonded surfaces were examined tactilely and under ×3.5 magnification, followed by light and scanning electron microscopy and recorded as either adhesive, cohesive, or mixed. Almost all failures in the glazed ZrO2 were mixed and cohesive. However, more adhesive failures were observed in the DPRC group of nonglazed ZrO2. ConclusionsNo differences were found between the 2 luting agents for the LDS. For the ZrO2 cubic and tetragonal layers, the DPRC had higher bond strengths to the nonglazed surfaces.

Effect of plasma treatment on the peel bond strength between maxillofacial silicones and resins.

The study aimed to investigate the effects of surface treatments, including plasma, on the peel bond strength between two maxillofacial silicones and two resins with and without thermocycling. Forty-eight experimental groups (n=10) were generated incorporating the two different resins (auto-polymerizing acrylic resin and light-curing urethane dimethacrylate resin [AR and LR, respectively]), two different silicones (M511 and Z004), aging (thermocycled/no thermocycling), and six different surface treatments, including polishing, grinding, polishing+argon plasma, polishing+oxygen plasma, grinding+argon plasma, and grinding+oxygen plasma. Surface topography of a specimen from each surface treatment group was examined by atomic force microscopy. After surface treatments, silicones were polymerized. The peel bond strength values of the control and thermocycled groups were determined. Atomic force microscopy showed that surface topographies of the ground specimens were irregular. Polished specimens showed higher peel bond strength than ground specimens. Plasma application appeared to have improved the bond strength between the resins and silicones.

Effect of Surface Treatment With Er:YAG and CO2 Lasers on Shear Bond Strength of Polyether Ether Ketone to Composite Resin Veneers.

Introduction: Polyether ether ketone (PEEK) has low surface energy and high resistance to chemical surface treatments. Therefore, different surface treatments such as laser conditioning should be investigated. There is a gap of information regarding the efficacy of laser irradiation in the surface treatment of PEEK, and the efficacy of several laser types needs to be evaluated for this purpose. This study aimed to assess the effect of surface treatment with erbium-doped yttrium aluminum garnet (Er:YAG) and carbon dioxide (CO2) lasers on shear bond strength (SBS) of PEEK to composite resin veneers. Methods: In this experimental study, 60 rectangular-shaped PEEK samples (7 x 7 x 2 mm) were used. The samples were mounted in auto-polymerizing acrylic resin in such a way that only one surface measuring 7x7 mm remained exposed. The samples were then randomly divided into 3 groups (n=20) of control, Er:YAG laser surface treatment (Power=1.5 W, energy density=119.42 J/cm2 , irradiation time=20 s) and CO2 laser surface treatment (Power=4 W, energy density=159.22 J/cm2 , irradiation time=50 s). The bonding agent and PEEK opaque were applied on the surface of samples and they were veneered with a composite resin using a hollow plastic cylinder with an internal diameter of 4 mm. The SBS was then measured and the data were analyzed using one-way ANOVA, Tukey HSD test and Dunnett's test at 0.05 level of significance. Results: The SBS of the 3 groups was significantly different (P<0.001). The Tukey HSD test revealed that the Er:YAG laser had higher SBS than the CO2 laser group (P<0.001). The Dunnett's test showed that both Er:YAG and CO2 laser groups yielded higher SBS than the control group (P<0.001). Conclusion: The Er:YAG and CO2 laser treatments can increase the SBS of PEEK to composite resin veneers, although the Er:YAG laser seems to be more effective for this purpose.

Effect of Two Methods of Remineralization and Resin Infiltration on Surface Hardness of Artificially Induced Enamel Lesions.

Statement of the Problem: The progression of incipient carious lesions may be simply prevented by non-invasive remineralization of lesions, eliminating the need for invasive and high-cost restorative procedures.Purpose: This study aimed to assess the effect of two commonly used remineralizing agents and resin infiltration on surface micro hardness of incipient enamel lesions at different time points.Materials and Method: In this in vitro study, 45 intact human maxillary central incisors were selected. After disinfection, enamel samples measuring 5x5x2.5 mm were cut out of the labial surface of the teeth. The surface of samples was polished and they were mounted in auto-polymerizing acrylic resin. According to Amaechi’s method, samples were immersed in acidified hydroxyethylcellulose system (pH= 4.5) for 96 hours to induce white spot lesions (WSLs). The baseline value of surface micro hardness of samples was measured using a Vickers hardness tester, then the samples were randomly divided into three groups (n=15) based on different remineralization methods: MI-Paste Plus, Remin Pro and ICON-Infiltrant according to the manufacturer’s instructions. All samples were stored in anti-dry mouth treatment agent during the experiment and their surface hardness was measured at 15 days (T1) and 20 weeks (T2). Results: The hardness of samples in MI-Paste Plus and Remin Pro groups significantly increased at both T1 and T2 (p< 0.001) but this increase was not significant in ICON group (p> 0.05).Conclusion: MI-Paste Plus and Remin Pro can efficiently increase the hardness of incipient enamel lesions.

Influence of Different Repair Acrylic Resin and Thermocycling on the Flexural Strength of Denture Base Resin.

Background and Objectives: Fractured acrylic denture base is a common occurrence in clinical practice. The effective denture repair procedure is cost-effective, time conserving, and results in lesser time without denture for the patient. Along with various reinforcements and surface modifications; different acrylic resins are investigated in improving the flexural strength of the fractured site. The aim of this study was to evaluate the flexural strength of a polymethyl methacrylate (PMMA) denture base repaired with heat-polymerized (HPA), auto-polymerized (APA) and light-polymerized acrylic (LPA) resins after thermocycling. Materials and Methods: Forty rectangular shaped (50 mm × 25 mm × 3 mm) PMMA specimens were fabricated. Group 1 specimens (n = 10) were kept as controls and the remaining 30 samples were sectioned at the center with a repair site dimension of 3 mm. The samples from three groups (n = 10) were repaired with HPA, APA, and LPA resins, respectively. The specimens were thermocycled for 5000 cycles and subjected to a three-point flexural test. The maximum load required to fracture the specimens was recorded, and further analyzed with ANOVA and the Games-Howell Post hoc test at the significance level p = 0.05. Results: The average maximum load and flexural strength of the control group was 173.60 N and 13.02 Mpa and corresponding values for denture repaired with HPA was 87.36 N and 6.55 Mpa. The corresponding values for APA resin and LPA resins were 62.94 N, 57.51 N, and 4.72 Mpa, 4.06 Mpa, respectively. Conclusions: The PMMA specimens repaired with HPA resins resulted in a significantly higher load to fracture compared to APA resin and LPA resin.

Impact of Surface Treatment with Different Repair Acrylic Resin on the Flexural Strength of Denture Base Resin: An In Vitro Study

The aim and objective of the present study was to assess the flexural strength of denture base resin based on surface treatment with different acrylic resin repair materials. Totally, 120 heat-polymerized polymethyl methacrylate denture base resin materials which are rectangular shaped with the size of 65 mm × 10 mm × 2.5 mm were fabricated. 150 μm-sized alumina used for surface treatment. All the 120 heat-cured, surface-treated acrylic denture base resin samples were randomly divided into three groups. Group I: glass-fiber-reinforced auto-polymerizing acrylic resin, group II: auto-polymerizing acrylic resin, and group III: light-cured acrylic resin. A universal testing machine was used to test the flexural strength of the repaired specimens. A highest mean flexural strength (88.96 ± 0.31) was demonstrated by group I, followed by group II (72.18 ± 1.86) and group III (66.30 ± 1.02). ANOVA demonstrated a statistically significant inter-group difference. On multiple comparisons, using Tukey's post hoc test a statistically significant difference between groups I and II and between groups I and III was found. After considering the limitations, the present study concluded that the highest flexural strength is shown by glass-fiber-reinforced auto-polymerizing acrylic resin than by auto-polymerizing acrylic resin and light-cured acrylic resin. Denture repair comprises of joining two fractured parts of a denture with a denture repair material. The success of denture repair depends on the adhesion phenomenon. The treatment of the surface can be accomplished using a suitable material which changes chemically and morphologically and thus promotes better adhesion.