Autopolymerizing Acrylic Resin Research Articles

Effect of Different Primers on the Peel Bond Strength between Silicone Elastomer and Acrylic Resins

Introduction: Implant-supported extra-oral prostheses often require a retentive matrix to hold gold alloy clips and magnets, which act as retentive means. Silicone elastomers have a different structure to acrylic resins. Hence, primers are used to increase the bonding between silicone and acrylic resin. Aim of Study: To investigate the effect of new platinum primers on the peel bond strength of silicone elastomer to acrylic resins. Materials and Methods: Peel bond strength of Cosmesil 2004 to two acrylic resins was assessed using two primers (MED6-161 and MED160) and no primer (control group). Sixty samples were prepared and divided into six groups according to the combination of acrylic resin, silicone, primer and no primer. All samples were then exposed to load in a universal testing machine with a cross head speed of 25 mm/min until failure. Data was analysed using STATA 12.1 software. Values of mean peel force between light and auto-polymerising acrylic resins were compared using two-way ANOVA and tukey HSD test. Results: The interaction between primers and acrylic resins had a significant effect on peel bond Original Research Article Al-Shammari; BJMMR, 8(12): 1034-1044, 2015; Article no.BJMMR.2015.535 1035 strength between Cosmesil 2004 and acrylic resins. MED6-161 primer significantly improved peel bond strength of Cosmesil 2004 to light-polymerising acrylic resin. However, MED-160 primer enhanced peel bond strength between Cosmesil 2004 and auto-polymerising acrylic resin. Conclusion: The combination of primer and acrylic is important in improving the bond strength. However, further investigation of different primers, silicones and different surface treatments to achieve the optimum bonding is need.

An alternative procedure of splinting multiunit implant copings to minimize the resin shrinkage

An accurate transfer of relationship of multi-unit implants from mouth to the master cast demands a rigid splinting of impression copings. Auto-polymerizing acrylic resin, the most commonly used material for such splinting, exhibits polymerization shrinkage resulting inaccurate transfer of spatial relationship of implants from mouth to the master cast. This article describes a simple laboratory and clinical procedure for minimizing this effect by sectional splinting approach. The technique utilizes the procedure of sectioning and rejoining of the resin between the impression copings, thus providing an adequate compensation for resin shrinkage. It assures an optimum accuracy of fit of one-piece cast implant framework while fabricating a full-mouth implant-supported prosthesis.

Colour Stability of Heat and Cold Cure Acrylic Resins

To evaluate the colour stability of heat and cold cure acrylic resins under simulated oral conditions with different colorants. Three different brands of heat cure acrylic resin and two rapid cure auto polymerizing acrylic resin of commercial products such as Trevelon Heat Cure (THC), DPI Heat cure (DHC), Pyrax Heat Cure (PHC), DPI Cold cure (DCC) and Acralyn-R-Cold cure (ACC) have been evaluated for discoloration and colour variation on subjecting it to three different, commonly employed food colorants such as Erythrosine, Tartarizine and Sunset yellow. In order to simulate the oral condition the food colorants were diluted with artificial saliva to the samples taken up for the study. These were further kept in an incubator at 37°C ± 1°C. The UV-visible spectrophotometer has been utilized to evaluate the study on the basis of CIE L* a* b* system. The prepared samples for standard evaluation have been grouped as control group, which has been tested with a white as standard, which is applicable for testing the colour variants. The least colour changes was found to be with Sunset Yellow showing AE* value of 3.55 with heat cure acrylic resin branded as PHC material and the highest colour absorption with Tartarizine showing AE* value of 12.43 in rapid cure autopolymerzing acrylic resin material branded as ACC material. ACC which is a self cure acrylic resin shows a higher colour variation to the tartarizine food coloration. There were not much of discoloration values shown on the denture base resins as the food colorants are of organic azodyes.

The Influence of Desensitizing Agent on the Bond Strength of Various Luting Cements

Background: Veneer restorations either an individual or component of fixed partial prosthesis play vital role in prosthetic dentistry. This study is carried out to evaluate retentivity of cementing medium i.e commercially available desensitizing agents. Aims & Objectives: 1. To evaluate the retentive ability of different luting cements used in Fixed Prosthodontics. 2. To compare the retentive ability of different luting cements used in Fixed Prosthodontics after application of desensitizing agents. Methods & Material: Three desensitizing materials are used i.e. Gluma, Systemp and Prime desensitizer. Zinc Phosphate, Zinc Polycarboxylate and Resin Reinforce Glass Ionomer cement used in study. Teeth were mounted in the auto polymerizing acrylic resin blocks. Sixty recently extracted caries free maxillary first premolar teeth of approximately similar sizes were selected. All sixty teeth grouped in to equal four groups. Group II, III & IV coated with Gluma, Systemp and Prime desensitizers respectively and group I left uncoated. Five samples from each group cemented with three different types of cement as mentioned. Samples were incubated and tested. Results: The application of Gluma desensitizing agent increases the tensile bond strength of the cements and the application of Systemp and Prime desensitizing agent does not have any significance on the tensile bond strength of luting agents.

Effect of Interchanging Liquid Components of Two Auto-Polymerizing Orthodontic Acrylic Resins in their Flexural Properties

Objective: To evaluate the effects of interchanging the liquid components of two commercially available orthodontic auto-polymerizing acrylic resin in their flexural properties, clarity and setting time

Does Abutment Collar Length Affect Abutment Screw Loosening After Cyclic Loading?

A significant vertical space that is corrected with vertical ridge augmentation may necessitate selection of longer abutments, which would lead to an increased vertical cantilever. This study investigated the influence of different abutment collar heights on single-unit dental implant screw-loosening after cyclic loading. Fifteen implant-abutment assemblies each consisted of an internal hexagonal implant were randomly assigned to 3 groups: Group1, consisting of 5 abutments with 1.5 mm gingival height (GH); Group2, 5 abutments with 3.5 mm GH; and Group3, 5 abutments with 5.5 mm GH. Each specimen was mounted in transparent auto-polymerizing acrylic resin block, and the abutment screw was tightened to 35 Ncm with an electric torque wrench. After 5 minutes, initial torque loss (ITL) was recorded for all specimens. Metal crowns were fabricated with 45° occlusal surface and were placed on the abutments. A cyclic load of 75 N and frequency of 1 Hz were applied perpendicular to the long axis of each specimen. After 500 000 cycles, secondary torque loss (STL) was recorded. One-way ANOVA analysis was used to evaluate the effects of abutment collar height before and after cyclic loading. One-way ANOVA showed that ITL among the groups was not significantly different (P = .52), while STL was significantly different among the groups (P = .008). Post-hoc Tukey HSD tests showed that STL values were significantly different between the abutments with 1.5 mm GH (Group1) and with 5.5 mm GH (Group3) (P = .007). A paired comparison t-test showed that cyclic loading significantly influenced the STL in comparison with the ITL in each group. Within the limitations of this study, it can be concluded that increase in height of the abutment collar could adversely affect the torque loss of the abutment screw.

Does abutment collar length affect abutment screw loosening after cyclic loading?

Abstract Background: Significant vertical space which has not been corrected with vertical ridge augmentation, may necessitate selection of longer abutments which would lead to an increased vertical cantilever.Purpose: This study investigated the influence of different heights of abutment collar on screw loosening of single-unit dental implants after cyclic loading.Material and methods: Fifteen implant-abutment assemblies each consisted of an internal hexagonal implant were randomly assigned to three groups. Three groups were arranged, Group1 consisted of five abutments with 1.5 mm gingival height (GH); Group2, five abutments with 3.5 mm gingival height, and Group3 consisted five abutments with 5.5 mm gingival height. Each specimen was mounted in transparent auto-polymerizing acrylic resin block and abutment screw was tightened to 35 N.cm with an electric torque wrench. After 5 minutes, Initial Torque Loss (ITL) was recorded for all specimens. Metal crowns were fabricated with 45oocclusal surface and were placed on the abutments. A cyclic load of 75 N and frequency of 1HZ was applied perpendicular to the long axis of each specimen. After 500000 cycles, Secondary Torque Loss (STL) was recorded. One way ANOVA analysis was used to evaluate the effects of abutment collar height before and after cyclic loading.Results: One-way ANOVA showed that ITL among the groups was not significantly different (P=.52), while STL was significantly different among three groups (P=.008). Post Hoc Tukey HSD Tests showed that STL values were significantly different between the abutments with 1.5 mm GH (Group1) and with 5.5 mm GH (Group3) (P=.007). Also, Paired comparison t-test showed that cyclic loading significantly influenced the STL in comparison with the ITL in each group. Conclusion: Within the limitation of this study, it can be concluded that increase in height of abutment collar could adversely affect the torque loss of abutment screw.

Retentiveness of various luting agents used with implant-supported prosthesis: an in vitro study.

Desired retrievability of cemented implant-supported fixed prosthesis makes the retentive strength of cementing agents an important consideration. The aim of the study was to evaluate the retentiveness of purposely designed implant cement and compare its retentiveness with dental cements that are commonly used with implant systems. Ten implant analogs were embedded in auto-polymerizing acrylic resin blocks and titanium abutments were attached to them. Fifty standardized copings were waxed directly on the abutment and casted. The cements used were: (1) resin-bonded zinc oxide eugenol cement, (2) purposely designed implant cement, (3) zinc phosphate cement, (4) zinc polycarboxylate cement, and (5) glass ionomer cement. After cementation, each sample was subjected to a pull-out test using universal testing machine and loads required to remove the crowns were recorded. The mean values and standard deviations of cement failure loads were analyzed using ANOVA and Bonferroni test. The mean values (± SD) of loads at failure (n = 10) for various cements were as follows (N): resin-bonded zinc oxide eugenol cement 394.62 (± 9.76), Premier implant cement 333.86 (± 18.91), zinc phosphate cement 629.30 (± 20.65), zinc polycarboxylate cement 810.08 (± 11.52), and glass ionomer cement 750.17 (± 13.78). The results do not suggest that one cement type is better than another, but they do provide a ranking order of the cements regarding their ability to retain the prosthesis and facilitate easy retrievability.

RETENTIVENESS OF VARIOUS LUTING AGENTS USED WITH IMPLANT SUPPORTED- PROSTHESIS: AN INVITRO STUDY

Abstract ABSTRACT:Purpose: Desired retrievability of cemented implant-supported fixed prosthesis makes the retentive strength of cementing agents an important consideration. The aim of the study was to evaluate the retentiveness of purposely-designed implant cement and to compare its retentiveness with dental cements that are commonly used with implant systems.Materials and method: Ten implant analogs were embedded in auto-polymerizing acrylic resin blocks and titanium abutments were attached to them. 50 standardized copings were waxed directly on the abutment and casted. The cements used were: 1. resin-bonded zinc oxide eugenol cement (Kalzinol, DPI), 2. purposely-designed implant cement (Premier implant cement), 3. zinc phosphate cement (DeTrey Zinc, Dentsply), 4. zinc polycarboxylate cement (Poly-F, Dentsply) and 5. glass ionomer cement (GC Gold Label, GC corporation, Japan). After cementation, each sample was subjected to a pull-out test using universal testing machine and loads required to remove the crowns were recorded. The mean values and standard deviations of cement failure loads were analyzed using ANOVA and Bonferroni test.Results: The mean values (±SD) of loads at failure (n = 10) for various cements were as follows (N): resin-bonded zinc oxide eugenol cement 394.62 (±9.76), Premier implant cement 333.86 (±18.91), zinc phosphate cement 629.30 (±20.65), zinc polycarboxylate cement 810.08 (±11.52) and glass ionomer cement 750.17 (±13.78).Conclusions: The results do not suggest that one cement type is better than another, but they do provide a ranking order of the cements in their ability to retain the prosthesis and to facilitate its easy retrievability.

Comparison of residual monomer loss from cold-cure orthodontic acrylic resins processed by different polymerization techniques

This investigation aimed to assess and compare the amount of residual monomer (RM) released from removable orthodontic appliances constructed by sprinkle-on and dough techniques. One hundred and twenty acrylic samples were prepared from orthodontic autopolymerized acrylic resins and divided into three groups, according to the processing method: sprinkle-on with polyclave, sprinkle-on without polyclave and dough technique. After polymerization, the specimens of each group were immersed in distilled water for 24 h, 48 h, 72 h and 1 week. High-performances liquid chromatography (HPLC) was utilized to measure residual monomer content. Maximum observed RM was 1284·91±129·07 ppm measured for sprinkle-on technique without polyclave after 24 h of water immersion. At this time, the level of RM was significantly different among the three applied techniques (P<0·05). In all soaking time groups, sprinkle-on technique with polyclave released the least amount of RM. Within each group, the maximum monomer releasing was observed after the first 24 h and decreases were observed in subsequent time groups. The reduction over the time was not significant in the polyclave groups (P>0·05). The sprinkle-on technique with polyclave and longer water immersion reduced residual monomer released from acrylic orthodontic appliances.

Indirect method of base adaptation against supporting element of tooth root for a partial overdenture prosthesis

The base of a partial overdenture prosthesis should be fitted intraorally against the supporting element of a tooth root. Chairside relining is a common method; however, an autopolymerizing acrylic resin presents high porosity when polymerized intraorally. This article describes an indirect method where an impression is made with a silicone occlusion registration material to create a replica of the supporting elements of the residual ridge and the tooth root in a high-viscosity polyvinyl siloxane impression material.

Evaluation of Retention of Custom- Made Posts Using Different Types of Luting Cements – An In-Vitro Study

This study was selected to evaluate and compare: The tensile strength of custom made posts using three different luting cements, namely Zinc phosphate cement (HARVARD), Glass ionomer cement (FUJI 1GC), Rely X U-100 Dual cure adhesive resin cement (3M ESPE). Sixty extracted single rooted mandibular premolar teeth were selected. Biomechanical preparation done, obturated and then post space prepared using peeso-reamer. The custom made nickel-chromium posts were fabricated for individual teeth. Posts were luted with three different adhesive luting cements and mounted on an acrylic block. The plastic cylindrical tubes were used to embed the specimens in auto polymerizing acrylic resin block. The whole assembly was gripped in a three jawed chuck and connected to the testing machine. The specimens were tested for tensile bond strength using an Instron testing machine. The machine was run to a cross head speed of 1mm/min. increasingly, heavy tensile load were applied to the specimen, till the post comes out the root canal by breaking the cement medium. The results were recorded in Newton’s and then converted to kilograms by dividing by 9.81. Retentive qualities were then statistically analyzed.

Fracture Resistance and Mode of Failure of Ceramic versus Titanium Implant Abutments and Single Implant‐Supported Restorations

The material of choice for implant-supported restorations is affected by esthetic requirements and type of abutment. This study compares the fracture resistance of different types of implant abutments and implant-supported restorations and their mode of failure. Forty-five Oraltronics Pitt-Easy implants (Oraltronics Dental Implant Technology GmbH, Bremen, Germany) (4 mm diameter, 10 mm length) were embedded in clear autopolymerizing acrylic resin. The implants were randomly divided into three groups, A, B and C, of 15 implants each. In group A, titanium abutments and metal-ceramic crowns were used. In group B, zirconia ceramic abutments and In-Ceram Alumina crowns were used. In group C, zirconia ceramic abutments and IPS Empress Esthetic crowns were used. Specimens were tested to failure by applying load at 130° from horizontal plane using an Instron Universal Testing Machine. Subsequently, the mode of failure of each specimen was identified. Fracture resistance was significantly different between groups (p < .05). The highest fracture loads were associated with metal-ceramic crowns supported by titanium abutments (p = .000). IPS Empress crowns supported by zirconia abutments had the lowest fracture loads (p = .000). Fracture modes of metal-ceramic crowns supported by titanium abutments included screw fracture and screw bending. Fracture of both crown and abutment was the dominant mode of failure of In-Ceram/IPS Empress crowns supported by zirconia abutments. Metal-ceramic crowns supported by titanium abutments were more resistant to fracture than In-Ceram crowns supported by zirconia abutments, which in turn were more resistant to fracture than IPS Empress crowns supported by zirconia abutments. In addition, failure modes of restorations supported by zirconia abutments were more catastrophic than those for restorations supported by titanium abutments.

Effect of Argon Plasma Pretreatment on Tensile Bond Strength of a Silicone Soft Liner to Denture Base Polymers

This study evaluated the effect of argon plasma treatment on tensile bonding of heat-cured and auto-polymerized acrylic resins prior to the processing of a silicone soft liner. Both types of polymethylmethacrylate (PMMA) resins were treated with argon plasma for 1 min or 10 min (n = 5). A control group, including untreated resin specimens, was also formed. After processing of the soft liner, the specimens were deflasked and stored dry for 24 h, and they were then subjected to tensile bond strength testing. In order to see the plasma effect on the resin surface chemistry, representative specimens were analysed by XPS. Highest tensile bond strengths were observed in the 1-min exposure group for each resin, and 10-min exposure yielded the lowest bond strength likely due to the damaging effect of the plasma treatment. XPS analysis showed that the O/C ratios increased greatly in treated samples and that the binding energy values were not significantly changed.

Strength comparison of four techniques to secure implant attachment housings to complete dentures

Implant overdentures become thinner and weaker after direct transfer of implant attachment housings. While much has been published on denture repair, these data do not directly apply to implant overdentures because the introduction of a metal housing changes the character of the repair. It is desirable to make a strong repair to avoid prosthesis fracture. The purpose of this study was to compare the flexural strengths of 4 different methods for chairside direct transfer of implant attachment housings. Eighty 11.5 × 9.1 × 39 mm heat-polymerized acrylic resin blocks were processed, assessed for porosities, and polished. An 8.5 mm diameter hole was drilled to a depth of 5 mm in the center of each block. Attachment housings were set into the bases with 4 different repair materials: autopolymerized acrylic resin (APAR), light-polymerized acrylic resin (LPAR), autopolymerized acrylic resin with silanated attachment housings (APSAH), and light-polymerized acrylic resin with silanated attachment housings (LPSAH). Blocks were immersed in water for 30 days in an incubator. A 3-point bend test was done in a universal testing machine, and load to fracture was recorded (MPa). Results were compared with 2-way ANOVA (α=.05). APSAH had the highest mean flexural strength at fracture (863.1 ±87 MPa) as compared to APAR (678.4 ±72.4 MPa), LPAR (550.9 ±119.3 MPa), and LPSAH (543.2 ±100.8 MPa). A comparison among the 4 groups showed that there were significant differences in maximum flexural strength (P<.001). The mean maximum strength of autopolymerized acrylic resin groups was significantly higher than light-polymerized acrylic resin groups. Silanation increased strength significantly compared to nonsilanated groups. The flexural strength of autopolymerized acrylic resin with silanated attachment housings was significantly higher than autopolymerized acrylic resin alone, light-polymerized acrylic resin alone, or light-polymerized acrylic resin with silanated attachment housings. Autopolymerized acrylic resin produced stronger constructs than light-polymerized materials.

FRACTURE RESISTANCE OF RESTORED MAXILLARY PREMOLARS

Extensively damaged teeth can be restored by different core build-up materials. The aim of this study was to examine the fracture resistance of restored maxillary premolars with composite resin, dental amalgam and glass ionomer cement (GIC) using compressive strength test. Also, to analyse the influence of bond strength of restorative materials on intact and carious dentin. Eighty extracted human maxillary premolars with intact and carious dentin were used in the study. The control group consisted of ten unrestored teeth with intact dentin. Artificial defect in dentin was prepared using diamond bur up to the half of the anatomic crown of the tooth. After core build-up procedure, each specimen was mounted in auto polymerizing acrylic resin blocks 2mm below cement enamel junction and they were kept in distilled water at 37 oC one day before testing. Then, they were placed in specially adapted devices at an angle of 183o to the longitudinal axis and subjected to a controlled load of 1mm per minute. There were significant differences among control group and restored teeth with composite resin, amalgam and GIC. Results showed that the best fracture values were obtained in control group (749,4N , then intact teeth restored with composite resin (492,5N) and amalgam (341,2N). In the group with carious dentin, values were lower, for composite resin 345,5 N and for amalgam 474,5N. There were no significant differences among restored groups with intact and carious dentin (p&lt;0.05). The fracture force corresponding to the teeth restored with GIC were significantly lower compared to the control group and the group with composite resin and amalgam. Satisfactory mechanical properties of restored premolars were obtained using composite resin and dental amalgam as a core build-up material. The carious-affected dentin led to lower bond strength of restored teeth.

FRACTURE RESISTANCE OF RESTORED MAXILLARY PREMOLARS

Extensively damaged teeth can be restored by different core build-up materials. The aim of this study was to examine the fracture resistance of restored maxillary premolars with composite resin, dental amalgam and glass ionomer cement (GIC) using compressive strength test. Also, to analyse the influence of bond strength of restorative materials on intact and carious dentin. Eighty extracted human maxillary premolars with intact and carious dentin were used in the study. The control group consisted of ten unrestored teeth with intact dentin. Artificial defect in dentin was prepared using diamond bur up to the half of the anatomic crown of the tooth. After core build-up procedure, each specimen was mounted in auto polymerizing acrylic resin blocks 2mm below cement enamel junction and they were kept in distilled water at 37 oC one day before testing. Then, they were placed in specially adapted devices at an angle of 183o to the longitudinal axis and subjected to a controlled load of 1mm per minute. There were significant differences among control group and restored teeth with composite resin, amalgam and GIC. Results showed that the best fracture values were obtained in control group (749,4N , then intact teeth restored with composite resin (492,5N) and amalgam (341,2N). In the group with carious dentin, values were lower, for composite resin 345,5 N and for amalgam 474,5N. There were no significant differences among restored groups with intact and carious dentin (p<0.05). The fracture force corresponding to the teeth restored with GIC were significantly lower compared to the control group and the group with composite resin and amalgam. Satisfactory mechanical properties of restored premolars were obtained using composite resin and dental amalgam as a core build-up material. The carious-affected dentin led to lower bond strength of restored teeth.

Shear Bond Strength of an Etch-and-rinse Adhesive to Er:YAG Laser- and/or Phosphoric Acid-treated Dentin.

Background and aims. Er:YAG laser irradiation has been claimed to improve the adhesive properties of dentin; therefore, it has been proposed as an alternative to acid etching. The aim of this in vitro study was to investigate the shear bond strength of an etch-and-rinse adhesive system to dentin surfaces following Er:YAG laser and/or phosphoric acid etching. Materials and methods. The roots of 75 sound maxillary premolars were sectioned below the CEJ and the crowns were embedded in auto-polymerizing acrylic resin with the buccal surfaces facing up. The buccal surfaces were ground using a diamond bur and polished until the dentin was exposed; the samples were randomly divided into five groups (n=15) according to the surface treatment: (1) acid etching; (2) laser etching; (3) laser etching followed by acid etching; (4) acid etching followed by laser etching and (5) no acid etching and no laser etching (control group). Composite resin rods (Point 4, Kerr Co) were bonded to treated dentin surfaces with an etch-and-rise adhesive system (Optibond FL, Kerr Co) and light-cured.After storage for two weeks at 37°C and 100% humidity and then thermocycling, bond strength was measured with a Zwick Universal Testing Machine at a crosshead speed of 1 mm/min. Data was analyzed using parametric and non-parametric tests (P<0.05). Results. Mean shear bond strength for acid etching (20.1±1.8 MPa) and acid+laser (15.6±3.5 MPa) groups were significantly higher than those for laser+acid (15.6±3.5 MPa), laser etching (14.1±3.4 MPa) and control (8.1±2.1 MPa) groups. However, there were no significant differences between acid etching and acid+laser groups, and between laser+acid and laser groups. Conclusion. When the cavity is prepared by bur, it is not necessary to etch the dentin surface by Er:YAG laser following acid etching and acid etching after laser etching.

Bond strength between acrylic resin and maxillofacial silicone

The development of implant dentistry improved the possibilities of rehabilitation with maxillofacial prosthesis. However, clinically it is difficult to bond the silicone to the attachment system.ObjectivesThis study aimed to evaluate the effect of an adhesive system on the bond strength between acrylic resin and facial silicone. Material and MethodsA total of 120 samples were fabricated with auto-polymerized acrylic resin and MDX 4-4210 facial silicone. Both materials were bonded through mechanical retentions and/or application of primers (DC 1205 primer and Sofreliner primer S) and adhesive (Silastic Medical Adhesive Type A) or not (control group). Samples were divided into 12 groups according to the method used to attach the silicone to the acrylic resin. All samples were subjected to a T-peel test in a universal testing machine. Failures were classified as adhesive, cohesive or mixed. The data were evaluated by the analysis of variance (ANOVA) and the Tukey's HSD test (α=.05). ResultsThe highest bond strength values (5.95 N/mm; 3.07 N/mm; 4.75 N/mm) were recorded for the samples that received a Sofreliner primer application. These values were significantly higher when the samples had no scratches and did not receive the application of Silastic Medical Adhesive Type A. ConclusionsThe most common type of failure was adhesive. The use of Sofreliner primer increased the bond strength between the auto-polymerized acrylic resin and the Silastic MDX 4-4210 facial silicone.

Evaluation of flexural strength of resin interim restorations impregnated with various types of silane treated and untreated glass fibres

BackgroundFlexural strength is an important mechanical property that determines the long-term prognosis of interim restorations. Studies are lacking regarding the effect of silanation of the various types of glass fibre impregnation on the flexural strength of resin interim restorations. MethodsA customized metal die was milled to simulate the prepared abutments of a three-unit fixed dental prosthesis. A total of seventy five samples of interim fixed dental prostheses were prepared using autopolymerizing tooth colour acrylic resin. Unidirectional and woven forms of glass fibres (Stick and Stick Net), which were silane treated and untreated were used to reinforce the resin matrix. Fifteen samples were prepared for each group along with unreinforced group serving as control. The flexural strength was evaluated with universal testing machine. ResultsThe means and standard deviations of flexural strength for different groups were 13.90 ± 2.96 (control), 61.58 ± 5.26 (unidirectional fibres), 30.89 ± 3.60 (woven fibres), 112.05 ± 5.51 (silane treated unidirectional fibres) and 73.85 ± 4.10 (silane treated woven fibres) respectively. The mean flexural strength of silane treated unidirectional fibres (112.05 MPa) was highest and statistically highly significant (P < 0.0001) compared to all other groups. ConclusionsWithin the limitations of the current study, flexural strength of the reinforced PMMA interim fixed dental prosthesis was significantly higher (P < 0.0001) when compared to the unreinforced PMMA interim fixed dental prosthesis. The use of silane treated unidirectional glass fibres is an effective method of reinforcing interim fixed restorations made of PMMA resins.