Resin adjustment of three-dimensional printed thermoset occlusal splints: Bonding properties - Short communication

Objectives: To evaluate the interfacial adhesion of an autopolymerizing acrylic resin to 3D printed thermoset occlusal splints compared to thermoplastic occlusal splints.Materials and methods: Cylinders made of an autopolymerizing acrylic resin were adhered to 3D printed thermoset and also to thermoplastic plates. A different surface treatment and three storage conditions were used: dry, 7 days water-storage and 14 days water-storage. Bond strength test (so-called shear-bond strength test) was afterward performed.Results: ANOVA (R2 = 0.764) revealed significant differences in bond strength according to material (p Conclusions: The bond strength of autopolymerizing acrylic resin to 3D printed thermoset plates is higher when compared to thermoplastic plates. Bonding between acrylic resin and 3D printed splints was high enough for clinical applications.conclusion</div

Mechanical Properties Evaluation of Three Different Materials for Implant Supported Overdenture: An In-Vitro Study

Aim: the aim of this study was to compare the flexural strength and elastic modulus of three-dimensionally (3D) printed, conventional heat-cured, and high-impact implant-supported overdenture materials specimens. Materials and Methods: Thirty implant-supported overdenture materials specimens (bar-shaped, 65.0 x 10.2 x 5.1 +/- 0.2 mm(3)) with one central hole were fabricated using 3D-printed, heat-cured conventional, and high-impact denture base resins (n = 10/group). Autopolymerizing acrylic resin was used to attach titanium matrix housings to the central holes of the specimens. A three-point bending test was conducted using a universal testing machine and a model analog with a crosshead speed of 5 mm/min. The indicative flexural strength and elastic modulus were recorded. Data were statistically analyzed using analysis of variance (ANOVA) and the Tukey tests at alpha = 0.05. Results: One-way ANOVA revealed a significant effect of denture base material on the flexural strength (p Conclusions: The maximum flexural strength was observed in the 3D-printed implant-supported overdenture material specimens, which might indicate their suitability as an alternative to the conventionally fabricated ones. Flexural strength and elastic modulus of conventional and high-impact heat-cured implant-supported overdenture materials specimens were comparable.</p

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 p p p </p

Dual-curing resin cement with colour indicator for adhesively cemented restorations to dental tissues: Change of colour by curing and some physical properties

The study was aimed to investigate a color indicator containing dual curing resin composite luting cement and to plot the color change to the time of solidification of the cement. In addition some physical properties were studied. Specimens were made of a dual-cure resin cement (Maxcem Elite™ Chroma, Kerr, Orange, CA, USA) and polymerized by autopolymerization only, or with light initiated polymerization. A spectrophotometer was used to quantify the color change of the cement as plotted with the curing time. The efficacy of the curing process was studied by measuring water sorption and the ultimate flexural properties of the cement. The results showed that the flexural strength of cement after autopolymerization was 27.3 MPa and after light initiated polymerization 48.1 MPa. Young's modulus of bending was 2089.3 MPa and 3781.5 MPa respectively for the same cement samples. Water sorption after two weeks for the autopolymerization cement samples was -1.12 wt% and for the light initiated polymerization samples 0.56 wt%. Non-parametric Spearman's correlation was measured for autopolymerized cement samples between variables for color and solidification load (N), which showed a strong correlation between curing process and color change (p < 0.05). There was a correlation between the color change and degree of monomer conversion of the dual curing resin composite luting cement which contained a color indicator system for polymerization reaction. The study also suggested that autopolymerization only resulted in suboptimal polymerization of the cement. By additional light curing considerably higher flexural properties were obtained.</p

Midline denture base strains of glass fiber-reinforced single implant-supported overdentures

Statement of problemThe fracture incidence of implant-supported overdentures is more frequent in the area of attachment because of stress concentration and denture deformation in this area. How E-glass fiber reinforcement can address this problem is unclear.PurposeThe purpose of this in vitro study was to evaluate the influence of unidirectional E-glass fiber reinforcement on the mid-line denture base strains of single implant-supported overdentures.Material and methodsAn experimental acrylic resin cast was constructed with a single implant placed in the mid-line area and a ball attachment screwed to the implant. Twenty-four experimental overdentures were constructed and divided into 4 groups: group AP fabricated from autopolymerizing acrylic resin without fiber reinforcement, group APF fabricated from autopolymerizing acrylic resin with unidirectional E-glass fiber reinforcement running over the residual ridge and the ball matrix, group HP fabricated from heat-polymerized acrylic resin without fiber reinforcement, and group HPF fabricated from heat-polymerized acrylic resin with unidirectional E-glass fiber reinforcement running over the residual ridge and the ball matrix. A biaxial rosette strain gauge was attached to the incisor areas of each overdenture above the attachment level (Ch1, Ch2) and to a multichannel digital strain meter. A static vertical load of 100 N was applied to the first molar area bilaterally by using a universal testing device during strain measurement procedures. The differences in the mean strain and deflection values among the investigated groups were evaluated for statistical significance using 1-way analysis of variance (ANOVA) with the Tukey post hoc multiple comparison (α=.05).ResultsThe type of acrylic resin did not have a statistically significant effect on the mean strain values among groups (P=.350), while the reinforcement did significantly affect them (PConclusionsUnidirectional E-glass fiber reinforcement placed over the residual ridge and implant attachment significantly reduced denture base strains and deformation of single implant-supported overdentures.</p

Influence of Monomer Systems on the Bond Strength Between Resin Composites and Polymerized Fiber-Reinforced Composite upon Aging

Purpose: This study examined the influence of different monomer systems on the tensile bond strength between a resin composite and a polymerized fiber-reinforced composite (FRC). The influence of the age (shelf-life) of the FRC prepreg (reinforcing fiber pre-impregnated with a resin system) before preparing the FRC substrate for the bonding test was also assessed.Materials and Methods: Semi-interpenetrating polymer network (semi-IPN)-based glass FRC prepregs were aged for various durations (1, 1.5, and 3 years) at 4 degrees C before being used to prepare FRC substrates via light polymerization. Four groups of aged prepregs were prepared through different treatments with: 1. no primer; 2. a dimethacrylate-based adhesive primer; 3. a universal primer; and 4. a specific composite primer. Subsequently, a resin composite luting cement was applied on the treated FRC substrates and cured with light. The water sorption of the FRC-composite specimens was determined. Then, the differences in the tensile bond strength were evaluated using ANOVA (p <= 0.05).Results: There were significant differences in the tensile bond strength between the composite cement and the FRC according to the primer used (p < 0.001), aging time (p < 0.001), and their interactive effect (p < 0.001).Conclusion: The monomers of the universal primer demonstrated the best ability to diffuse into the semi-IPN structure of the polymer matrix of FRC. This improved the interfacial bond strength between the composite cement and the FRC substrate

The effect of ethanol on surface of semi-interpenetrating polymer network (IPN) polymer matrix of glass-fibre reinforced composite

Aim of the study:The aim of this laboratory study was to evaluate the effect of ethanol treatment on the surfaceroughness (Sa), nano-mechanical properties (NMP) and surface characterization of dentalfiber reinforcedcomposite (FRC) with semi-interpenetrating polymer network (IPN).Materials and methods:A total of 240 FRC specimens with bisphenol A-glycidyl methacrylate - triethyleneglycoldimethacrylate–Poly (methylmetahcrylate) (bis-GMA-TEGDMA-PMMA) IPN matrix system were light cured for40 s and divided into 2 groups (L and LH). The group LH was further post-cured by heat at 95 °C for 25 min. Thespecimens were exposed to 99.9%, 70% and 40% for 15, 30, 60 and 120 s respectively. The treated specimenswere evaluated for Sausing non-contact profilometer. NMP were determined using nanoindentation techniqueand chemical characterization was assessed by Fourier Transform-Infrared (FTIR) spectroscopic analyses.Scanning electron microscopic (SEM) images were made to evaluate the surface topographical changes.Results:Both the L and LH group showed changes in the Saand NMP after being treated by different con-centrations of ethanol and at different time interval. The highest Sawas observed with L-group (0.733μm)treated with 99.9% ethanol for 120 s. Specimens in LH-group treated with 99.9% ethanol for 120 s (1.91 GPa)demonstrated increased nano-hardness, and group treated with 40% ethanol for 120 s demonstrated increasedYoung's modulus of elasticity (22.90 GPa). FTIR analyses revealed changes in the intensity and bandwidth inboth the L and LH groups.Conclusion:The present study demonstrated that both light-cured and heat post-cured FRC were prone forethanol induced alteration in the surface roughness (Sa), nano-mechanical properties (NMP) and chemicalcharacterization. The interphase between the glassfibers and the organic matrix was affected by ethanol. Thechanges were considerably less in magnitude in the heat post-cured FRC specimens.</p

Interfacial Adhesion of a Semi-Interpenetrating Polymer Network-Based Fiber-Reinforced Composite with a High and Low-Gradient Poly(methyl methacrylate) Resin Surface

The research aimed to determine the tensile bond strength (TBS) between polymerized intact and ground fiber-reinforced composite (FRC) surfaces. FRC prepregs (a reinforcing fiber pre-impregnated with a semi-interpenetrating polymer network (semi-IPN) resin system; everStick C&B) were divided into two groups: intact FRCs (with a highly PMMA-enriched surface) and ground FRCs (with a low PMMA gradient). Each FRC group was treated with: StickRESIN and G-Multi PRIMER. These groups were further divided into four subgroups based on the application time of the treatment agents: 0.5, 1, 2, and 5 min. Next, a resin luting cement was applied to the FRC substrates on the top of the photo-polymerized treating agent. Thereafter, weight loss, surface microhardness, and TBS were evaluated. Three-factor analysis of variance (p <= 0.05) revealed significant differences in the TBS among the FRC groups. The highest TBS was recorded for the intact FRC surface treated with G-Multi PRIMER for 2 min (13.0 +/- 1.2 MPa). The monomers and solvents of G-Multi PRIMER showed a time-dependent relationship between treatment time and TBS. They could diffuse into the FRC surface that has a higher PMMA gradient, further resulting in a high TBS between the FRC and resin luting cement

Biomechanical aspects of reinforced implant over-dentures: a systematic review

AbstractPurposeThe purpose of this systematic review was to investigate the effect of reinforcement on the mechanical behaviour of implant overdenture (IOD) bases and its cumulative biological effect on the underlying supporting structures (implants and the residual ridge).Material and methodsThe required documents were collected electronically from PubMed and Web of Science databases targeting papers published in English that focused on denture base reinforcement for IOD prostheses in order to recognize the principal outcomes of reinforcement on the mechanical and biological properties of overdentures. Such biological outcomes as: strains on implants, peri-implant bone loss, residual ridge resorption, and strain on the residual alveolar ridge.ResultsA total of 269 citations were identified. After excluding any repeated articles between databases and the application of exclusion and inclusion criteria, only 13 publications fulfilled the inclusion criteria. Three publications investigated the mechanical properties of fibre and/or metal-reinforced implant overdentures while another 3 articles investigated the effect of metal reinforcement on stress distribution and strains transmitted to the underlying implants. In addition, 3 in vitro studies investigated the effect of metal reinforcement on overdenture base strain and stresses. Stress distribution to the residual ridge and strain characteristics of the underlying tissues were investigated by 2 in vitro studies. Five clinical studies performed to assist the clinical and prosthetic maintenance of metal-reinforced IOD were included. Data concerning denture base fracture, relining, peri-implant bone loss, probing depth, and implant survival rates during the functional period were extracted and considered in order to evaluate the mechanical properties of the denture base, residual ridge resorption and implant preservation rates, respectively.ConclusionThe use of a denture base reinforcement can reduce the fracture incidence in IOD bases by enhancing their flexural properties and reducing the overdenture base deformation. Strains on the underlying supporting structures of overdenture prostheses including dental implants and the residual ridge can be decreased and evenly distributed using a metal reinforcement.</div