Interim Restorative Material Research Articles

Retracted: Influence of the Physical Inclusion of ZrO2/TiO2 Nanoparticles on Physical, Mechanical, and Morphological Characteristics of PMMA-Based Interim Restorative Material.

[This retracts the article DOI: 10.1155/2022/1743019.].

Comparison of the Flexural Strength and Elastic Modulus of Conventional, Milled and 3D-Printed Interim Restorative Materials Subjected to Different Intervals of Accelerated Aging

Comparison of the Flexural Strength and Elastic Modulus of Conventional, Milled and 3D-Printed Interim Restorative Materials Subjected to Different Intervals of Accelerated Aging

Evaluating the conversion degree of interim restorative materials produced by different 3-dimensional printer technologies

Statement of problemThree-dimensional (3D) printers are a relatively new technology, but the degree of conversion (DC) of the resin specimens produced by using this method is currently unknown. However, the DC of resin interim restorative materials is critical for their biocompatibility and physical properties. PurposeThe purpose of this in vitro study was to evaluate the DC of interim restorative materials produced by using different 3D printer technologies and compare them with conventionally manufactured polymethyl methacrylate. Material and methodsStereolithography, digital light processing, and liquid crystal display 3D printers were used as experimental groups, and a conventional (C) method was used as the control. Five different 3D printers (DWS Systems, Formlabs [FL], Asiga, Mega, and Vega) were included. The 3D printed specimens were designed in a rectangular prism geometry (10×4×2.5 mm) by using a computer-aided design software program (Materialise 3-matic) and printed with a layer thickness of 50 µm in the horizontal direction (n=15). Fourier transform infrared spectroscopy (FT-IR) spectra were measured in 3 steps: the liquid state of the resins, after washing with 99% isopropanol, and after final polymerization. For the C method, FT-IR spectra were assessed in 2 steps: immediately after mixing the liquid and powder and after polymerization. Statistical analysis of the data was performed with 1-way ANOVA followed by the post hoc Tukey honestly significant difference (HSD) test (α=.05). ResultsThere was no statistically significant difference in DC values between the 3D printed groups (P>.05). There was a statistically significant difference only between FL and the C in terms of DC (P=.042). ConclusionsThree-dimensionally printed interim resin materials found comparable results with those of the C group. The DC was not affected by different 3D printing technologies.

Trueness, Flexural Strength, and Surface Properties of Various Three-Dimensional (3D) Printed Interim Restorative Materials after Accelerated Aging.

Various 3D printing systems for interim fixed dental restorations are commercially available. This study aimed to evaluate the physical and mechanical properties of 3D printed resins used for interim restorations fabricated using various 3D printing systems and printing angulations after accelerated aging. Three different interim restorative materials were provided and printed using their specific 3D printing systems (A: NextDent; B: Asiga; C: Nova3D), and the testing specimens from each system were printed at two building angles: (1) 0° and (2) 90°. The six groups were A1, A2, B1, B2, C1, and C2, with sixteen specimens per group. Half of the specimens in each group (N = 8) were subjected to accelerated aging, including simulated brushing and thermocycling. Three-point bending, surface roughness, and Vickers microhardness tests were performed. Two-way ANOVA and Fisher's multiple tests were used for statistical analyses. The most accurate systems were found in groups C1 and C2 for length, A1 and B1 for width, and A1 and C1 for height. The specimen trueness only changed after aging for groups B1, B2, and C1. The flexural strength of the A2 group (151 ± 7 MPa) before aging was higher than that of the other groups, and the strength decreased after aging only for groups A1 and A2. The flexural strength, microhardness, and surface roughness of the 3D printed interim resins after aging varied depending on the material, system used, and printing angle.

Evaluation of Mechanical Behavior of CAD/CAM Polymers for Long-term Interim Restoration Following Artificial Aging.

Mechanical properties are crucial parameters for the clinical performance of longterm CAD/CAM interim restorations. This study aimed to evaluate and compare fracture toughness (FT), flexural strength (FS), flexural modulus (FM), microhardness (H), and the brittle index (BI) of three different long-term interim restorative materials after simulated ageing. CAD-Temp; VCT, Everest C-Temp; CT, and PEEK; PK were the materials used. Specimens were divided into subgroup A (control group) with no thermocycling, and subgroup B subjected to 5000 thermocycles between 5 and 55 °C for 30 seconds. FS, FM, FT, H, microstructure, and the brittle index were evaluated. The data was examined using two-way ANOVA and Tukey's test for post-hoc comparisons. In the VCT group, FS, FT, and H were significantly reduced (p ⟨0.05) after thermocycling. In the PK group, no statistically significant differences (p ⟩0.05) were detected between the aged and non-aged groups. As for the CT group, the tested properties were significantly reduced (p ⟨0.05) after simulated aging condition. The PK group recorded appropriate mechanical behavior both before and after simulating aging, in addition to its better machinability than other materials. The CT group had better mechanical properties before and after ageing, despite the significant reduction in mechanical properties after aging.

Application and trends in provisional dental restorative materials for fixed partial denture

A provisional restoration must protect the prepared tooth, restore form and function which should be esthetically acceptable. Sometimes, they are made to assess the outcome of a specific therapy for definitive prosthesis. Hence, understanding the properties, manipulation methods, and uses of provisional restorative materials for fixed partial denture is essential for all dentists. The objective of the study was to assess the recent advancement in provisional restorative materials for dental prosthesis available now. Literature search on PubMed and Google Scholar was done from January 1965 to March 2022 using the keywords such as provisional and interim restorative materials. In addition, hand search was done through refereed dental journals for 2000 to 2022. Nanoparticle-reinforced provisional restorative materials for any fixed dental prosthesis had better mechanical properties compared to conventional provisional materials available in the market. Digitally fabricated provisional materials eliminate the impression and the laboratory fabrication procedures, so that it consumes less time for fabrication.

Color stability, surface roughness and flexural strength of additively manufactured and milled interim restorative materials after aging.

To evaluate the effect of two different additive manufacturing technologies on the color stability, surface roughness and biaxial flexural strength of interim restorative materials after thermal aging. Disk-shaped specimens were manufactured via two types of vat polymerization methods [Stereo-lithography (SLA) and digital light processing (DLP)] and milling technology (n = 16). CIELab color coordinates and surface roughness were measured before and after thermal cycling. Then biaxial flexural strength tests were performed using a universal testing machine. The data were analyzed by Kruskal-Wallis, one-way ANOVA, and Tamhane and Tukey HSD tests (α < 0.05). There was no significant difference among ΔE values of all study groups (p = 0.191). The milled group showed a higher initial surface roughness value (p < 0.05), while there was no significant difference among the other groups after aging (p = 0.213). DLP had significantly lower flexural strength values than SLA and Milled (p = 0.000). After aging, SLA and DLP were similar to milling method, in terms of color stability and surface roughness. However, milling had an adverse effect on the initial surface roughness. The SLA and milled groups had better mechanical properties than the DLP group.

Influence of the Physical Inclusion of ZrO2/TiO2 Nanoparticles on Physical, Mechanical, and Morphological Characteristics of PMMA-Based Interim Restorative Material.

Polymethyl methacrylate (PMMA) is often used in restorative dentistry for its easy fabrication, aesthetics, and low cost for interim restorations. However, poor mechanical properties to withstand complex masticatory forces are a concern for clinicians. Therefore, this study aimed to modify a commercially available PMMA-based temporary restorative material by adding TiO2 and ZrO2 nanoparticles in different percentages as fillers and to investigate its physio-mechanical properties. Different percentages (0, 0.5, 1.5, and 3.0 wt%) of TiO2 and ZrO2 nanoparticles were mixed with the pristine PMMA resin (powder to liquid ratio: 1 : 1) and homogenized using high-speed mixer. The composites obtained were analyzed for their flexural strength (F.S.), elastic modulus (E.M.), Vickers hardness (H.V.), surface roughness Ra, morphology and water contact angle (WCA). The mean average was determined with standard deviation (SD) to analyze the results, and a basic comparison test was conducted. The results inferred that adding a small amount (0.5 wt%) of TiO2 and ZrO2 nanoparticles (NPs) could significantly enhance the physio-mechanical and morphological characteristics of PMMA interim restorations. EM and surface hardness increased with increasing filler content, with 3.0 wt.% ZrO2 exhibiting the highest EM (3851.28 MPa), followed by 3.0 wt.% TiO2 (3632.34 MPa). The WCA was significantly reduced from 91.32 ± 4.21° (control) to 66.30 ± 4.23° for 3.0 wt.% ZrO2 and 69.88 ± 3.55° for 3.0 wt.% TiO2. Therefore, TiO2 and ZrO2 NPs could potentially be used as fillers to improve the performance of PMMA and similar interim restorations.

Color and surface stainability of additively and subtractively manufactured interim restorative materials against mouth rinses

Statement of problemInterim restorations are often used along with mouth rinses during the healing period following surgical procedures. However, evidence regarding the color and surface properties of digitally fabricated interim restorations after oral rinsing is lacking. PurposeThe purpose of this in vitro study was to evaluate whether different mouth rinses could affect the color and surface roughness of milled and printed interim restorations after simulated oral rinsing. Material and methodsDisk-shaped specimens (Ø15×2 mm; N=180) were fabricated by using conventional (Jet Tooth Shade), milled (Yamahachi PMMA Disk), and printed (NextDent C&B) resin materials. All resin specimens were divided into 3 different groups according to the rinsing material: distilled water, whitening mouth rinse (Listerine Healthy White), and conventional mouth rinse (Listerine Cool Mint). The specimens were further allocated into short- and long-term subgroups, and oral rinsing simulation was performed (n=10). Short-term rinsing simulated the conditions in a usual interim restoration period, and long-term rinsing was performed to evaluate the properties of the interim materials. The color differences (CIEDE2000, ΔE00) between the baseline and each time point were determined by using a spectrophotometer. The surface roughness of the tested specimens was measured by using a confocal laser scanning microscope. Kruskal-Wallis and Friedman tests with nonparametric pairwise comparisons were used to analyze the data (α=.05). ResultsOn simulation of a 6-month use of the mouth rinse, the color change in the milled resin did not differ from that in the conventional resin (P>.334), but the printed resin showed a significantly greater color change than the other resins (P<.007). The greatest color change with the printed resin was observed when a conventional mouth rinse was used. However, all color changes were below a perceptible threshold of 1.30. When daily rinsing for 14 years was simulated, all resin groups showed a perceptible color change when conventional mouth rinse was used, and the printed resin showed the greatest median ±interquartile range ΔE00 (2.24 ±0.2). In both short- and long-term simulations, the printed resin rinsed with the conventional mouth rinse showed significantly greater roughness than that rinsed with distilled water (P<.009). ConclusionsThe printed resin showed higher stainability than the conventional resin, and the color change was greatest with the conventional mouth rinse. However, in 6 months of daily mouth rinse simulation, all the tested resin materials exhibited imperceptible color change and clinically acceptable surface roughness.

Comparative evaluation of coronal sealing ability of light cure temporary restorative materials with conventional temporary restorative material using stereomicroscope

Background: The coronal seal is a crucial factor in success of endodontic therapy. Hence the aim of the present study was to assess the sealing ability by evaluating microleakage of three different types of interim restorative materials. Method: A total of 80 extracted human premolars were divided randomly in to 4 groups. Group A: Control group, Group B: Systemp Inlay, Group C: Temp IT Blue, Group D: Cavit-G. Standardized access cavity preparation was done followed by placement of cotton pellet in the access cavity, Interim restorative materials were placed as per the assigned group of restorative materials. Teeth were stained with 2% methylene blue solution for 1 week after which all the teeth were analysed for dye penetration under stereomicroscope. Statistical analysis of data was done using one-way ANOVA and Post Hoc Tukey test with a significance level of P ≤ 0.05. Results: Systemp Inlay showed the least micro leakage value followed by Temp.it blu and Cavit G. Intergroup comparison showed statistically significant difference between Systemp Inlay and other groups whereas Temp IT Blue and Cavit G showed no statistical significance.

Influence of definitive and interim restorative materials and surface finishing on the scanning accuracy of an intraoral scanner

PurposeTo analyze the influence of the restorative material type (definitive and interim) and its surface treatment (polished or glazed) on the scanning accuracy of an intraoral scanner. Material and methodsA mandibular dental typodont containing 3 typodont teeth (left second premolar and left first and second molars) was used for testing. Ten groups were created based on the crown material: typodont tooth (control group), gold (G group), zirconia (Z group), lithium disilicate (LD group), hybrid ceramic (HC group), composite resin (CR group), conventional PMMA (CNV-PMMA group), bis-acryl composite resin (CNV-BA group), milled PMMA (M-PMMA group), and additively manufactured bis-acryl-based polymer (AM-BA group). Except the G group, groups were subdivided into polished (P subgroups) or glazed (G subgroups). Each specimen was digitized by using an extraoral scanner (D1000; 3Shape A/G) and an intraoral scanner (TRIOS 4; 3Shape). Each reference scan was used to measure the discrepancy with the corresponding 15 intraoral scans by calculating the root mean square (RMS) error (Geomagic; 3D Systems). The Welch ANOVA and Games-Howell tests were selected to examine trueness (α=0.05). The F-test with Bonferroni correction was used to evaluate precision. ResultsSignificant trueness and precision differences were found (P<.001). The G-P subgroup had the lowest trueness values, while the CNV-PMMA-P, M-PMMA-P, and AM-BA-P subgroups had the highest trueness values. Significant RMS mean discrepancies were computed when comparing polished and glazed specimens fabricated with the same material (P<.001). The CNV-PMMA-G subgroup had the lowest precision values, while the CNV-BA-P subgroup had the highest precision values (P<.001). ConclusionsThe type and surface finishing of the restorative materials tested influenced the scanning accuracy of the IOS tested. The lowest trueness values were found in the high noble alloy specimens, while the highest trueness values were measured in conventional and milled PMMA and additively manufactured bis-acryl-based polymer polished specimens. Except for zirconia crowns, higher trueness values were found in polished specimens when compared with glazed crowns. The CNV-PMMA-G subgroup had the lowest precision values, while the highest precision values were measured in the CNV-BA-P subgroup. CLINICAL SIGNIFICANCEDefinitive and interim materials tested decrease intraoral scanning accuracy. Furthermore, polishing instead of glazing definitive and interim material assessed might be preferable to maximize intraoral scanning accuracy.

Surface roughness and shear bond strength to composite resin of additively manufactured interim restorative material with different printing orientations

Statement of problemAdditive manufacturing (AM) is a technology that has been recently introduced into dentistry for fabricating dental devices, including interim restorations. Printing orientation is one of the important and influential factors in AM that affects the accuracy, surface roughness, and mechanical characteristics of printed objects. However, the optimal print orientation for best bond strength to 3D-printed interim restorations remains unclear. PurposeThe purpose of this in vitro study was to evaluate the effect of printing orientation on the surface roughness, topography, and shear bond strength of AM interim restorations to composite resin. Material and methodsDisk-shaped specimens (Ø20×10 mm) were designed by a computer-aided design software program (Geomagic freeform), and a standard tessellation language (STL) file was obtained. The STL file was used for the AM of 60 disks in 3 different printing orientations (0, 45, and 90 degrees) by using E-Dent 400 C&B material. An autopolymerizing interim material (Protemp 4) was used as a control group (CNT), and specimens were fabricated by using the injecting mold technique (n=20). Surface roughness (Sa, Sz parameters) was measured by using a 3D-laser scanning confocal microscope (CLSM) at ×20 magnification. For shear bond testing, the specimens were embedded in polymethylmethacrylate autopolymerized resin (n=20). A flowable composite resin was bonded by using an adhesive system. The specimens were stored in distilled water at 37 °C for 1 day and thermocycled 5000 times. The shear bond strength (SBS) was measured at a crosshead speed of 1 mm/min. The data were analyzed by 1-way ANOVA, followed by the Tukey HSD test (α=.05). ResultsThe 45-degree angulation printing group reported the highest Sa, followed by the CNT and the 90-degree and 0-degree angulations with significant difference between them (P<.001). The CNT showed the highest Sz, followed by the 45-degree, 90-degree, and 0-degree angulations. The mean ±standard deviation SBS was 28.73 ±5.82 MPa for the 90-degree, 28.21 ±10.69 MPa for the 45-degree, 26.21 ±11.19 MPa for the 0-degree angulations and 25.39 ±4.67 MPa for the CNT. However, no statistically significant difference was found in the SBS among the groups (P=.475). ConclusionsPrinting orientation significantly impacted the surface roughness of 3D-printed resin for interim restorations. However, printing orientation did not significantly affect the bond strength with composite resin.

Influence of Polymeric Restorative Materials on the Stress Distribution in Posterior Fixed Partial Dentures: 3D Finite Element Analysis.

Background: This study evaluated the effect of interim restorative materials (acrylic resin (AR), resin composite (RC) or polyetheretherketone (PEEK) for dental computer-aided design/computer-aided manufacturing (CAD/CAM)) on the stress distribution of a posterior three-unit fixed partial denture. Methods: The abutment teeth (first molar and first premolar) were modeled using the BioCAD protocol containing 1.5 mm of axial reduction and converging axial walls. A static structural analysis was performed in the computer-aided engineering software, and the Maximum Principal Stress criterion was used to analyze the prosthesis and the cement layers of both abutment teeth. The materials were considered isotropic, linearly elastic, homogeneous and with bonded contacts. An axial load (600 N) was applied to the occlusal surface of the second premolar. Results: Regardless of the restorative material, the region of the prosthetic connectors showed the highest tensile stress magnitude. The highest stress peak was observed with the use of RC (129 MPa) compared to PEEK and AR. For the cement layers, RC showed the lowest values in the occlusal region (7 MPa) and the highest values for the cervical margin (14 MPa) compared to PEEK (21 and 12 MPa) and AR (21 and 13 MPa). Conclusions: Different interim restorative materials for posterior fixed partial dentures present different biomechanical behavior. The use of resin composite can attenuate the stress magnitude on the cement layer, and the use of acrylic resin can attenuate the stress magnitude on the connector region.

Wear of 3D printed and CAD/CAM milled interim resin materials after chewing simulation.

PURPOSEThe purpose of this in vitro study was to investigate the wear resistance and surface roughness of three interim resin materials, which were subjected to chewing simulation.MATERIALS AND METHODSThree interim resin materials were evaluated: (1) three-dimensional (3D) printed (digital light processing type), (2) computer-aided design and computer-aided manufacturing (CAD/CAM) milled, and (3) conventional polymethyl methacrylate interim resin materials. A total of 48 substrate specimens were prepared. The specimens were divided into two subgroups and subjected to 30,000 or 60,000 cycles of chewing simulation (n = 8). The wear volume loss and surface roughness of the materials were compared. Statistical analysis was performed using one-way analysis of variance and Tukey's post-hoc test (α=.05).RESULTSThe mean ± standard deviation values of wear volume loss (in mm3) against the metal abrader after 60,000 cycles were 0.10 ± 0.01 for the 3D printed resin, 0.21 ± 0.02 for the milled resin, and 0.44 ± 0.01 for the conventional resin. Statistically significant differences among volume losses were found in the order of 3D printed, milled, and conventional interim materials (P<.001). After 60,000 cycles of simulated chewing, the mean surface roughness (Ra; μm) values for 3D printed, milled, and conventional materials were 0.59 ± 0.06, 1.27 ± 0.49, and 1.64 ± 0.44, respectively. A significant difference was found in the Ra value between 3D printed and conventional materials (P=.01).CONCLUSIONThe interim restorative materials for additive and subtractive manufacturing digital technologies exhibited less wear volume loss than the conventional interim resin. The 3D printed interim restorative material showed a smoother surface than the conventional interim material after simulated chewing.

Physical and surface properties of a 3D-printed composite resin for a digital workflow

Statement of problemInformation related to the optical and surface properties, including health compatibility, surface roughness, and esthetics, of 3D-printed dental materials is scarce. PurposeThe purpose of this in vitro study was to compare the physical and surface properties of a 3D-printed resin with those of materials used for interim restorations. Material and methodsA 3D-printed resin (PR) (NextDent C&B MFH; 3D Systems), an autopolymerizing interim material (BA) (Protemp 4; 3M ESPE), and a composite resin (Z350) (Filtek Z350XT; 3M ESPE) were tested for degree of color change (ΔE) (n=7) at different timepoints—24 hours after polishing/baseline (P0), 8 days after polishing (P1), and after artificial aging in water at 60 °C for 24 hours (P2)—by using a CIELab-based colorimeter; flexural strength (σ) (n=10) with a 3-point bend test; Knoop hardness (H) (n=8); and surface roughness (Ra) (n=7) with a profilometer. All specimens were polished 24 hours after polymerization, except for the additional group for surface roughness (BA) without polishing (BANP). A statistical analysis was performed by using 2-way repeated-measures ANOVA followed by the Fischer test for ΔE and 1-way ANOVA followed by the Fisher test for microhardness and surface roughness (α=.05). ResultsThe Z350 showed the highest values for σ and H, followed by PR. BA showed the lowest results for both tests (P<.05). Considering roughness, the Z350 showed similar values to those of BA but lower than PR; PR showed similar roughness when compared with BA. PR showed the highest color variation among the groups at all timepoints, followed by BA. The Z350 was the most color stable material at all timepoints. ConclusionsThe 3D-printed composite resin had adequate mechanical and surface properties for an interim restorative material. It has the potential to be a low-cost workflow in dentistry, although its color stability could be a concern for long-term use.

Color dimensions of additive manufactured interim restorative dental material

Statement of problemInterim dental restorations can be fabricated by using additive manufacturing (AM) technologies. Although dental restoration contours can be easily and accurately fabricated by using computer-aided design (CAD) procedures, protocols for creating predictable color dimensions of AM interim restorations are lacking. PurposeThe purpose of this in vitro study was to measure and compare color dimensions of different AM and conventional interim restorative materials. Material and methodsDisks (N=420) were fabricated by using either conventionally (CNV group) or additively manufactured (AM group) materials. The CNV group was further divided into the subgroups CNV-1 (Protemp 4; 3M ESPE) and CNV-2 (Anaxdent new outline dentin; Anaxdent). AM subgroups included AM-1 (FreePrint temp; Detax), AM-2 (E-Dent 400; Envisiontec), AM-3 (NextDent C&B; NextDent), AM-4 (NextDent C&B MFH; NextDent), and AM-5 (Med620 VEROGlaze; Stratasys). Color measurements in the CIELab coordinates were made by using a spectrophotometer (VITA EasyShade Advance 4.0; VITA) with a standardized photography gray card as a background under room light conditions (1003 lux). Color difference (ΔE*) values were calculated by using the CIE76 and CIEDE2000 formulas. The data were analyzed by using the Kruskal-Wallis test with nonparametric pairwise comparisons. ResultsOwing to a software error, the spectrophotometer was unable to measure the color of any specimens in the AM-5 subgroup, which was consequently excluded from further analysis. Significant differences (P=.001) between 2 manufacturing groups were found based on the L* variable. All subgroups were significantly different from each other for all 3 variables (P<.001). Pairwise comparisons revealed that all groups were significantly different from each other, except for the AM-1 and AM-2 subgroups, compared with the CNV-1 subgroup for the L* color dimension. The ΔE* values calculated by using the CIE76 formula varied from 6.63 to 23.1 and by using the CIEDE2000 formula from 3.43 to 10.21, suggesting a perceptible and unacceptable color mismatch between the CNV and AM groups. ConclusionsNone of the additively manufactured interim materials tested matched the conventional interim materials in all 3 CIELab color dimensions.

EFFECT OF HUMAN ENAMEL ON WEAR OF THREE TYPES OF INTERIM RESTORATIVE MATERIALS (AN IN-VITRO STUDY)

Objectives: The purpose of the present study was to determine wear behavior of two different composite resin; UDMA / Urethane Dimethacrylate and bis-GMA based, compared with a PMMA conventional resin interim restorative materials. Materials and Methods: Thirty samples (10 of each material; Revotek LC, TempSpan, Jet tooth shade) were prepared in the form of discs (10 mm diameter and 2 mm thickness), then all samples were subjected to Two-body wear simulation test using a programmable logic controlled equipment. Human enamel was used in this study as specimen’s antagonist. Two wear measurement protocols; 1- roughness change measurement using the optical profilometry and, 2- weight loss measurement by electronic analytical balance were performed before and after loading Results: Roughness change comparison between the experimental material groups showed that the highest roughness change was recorded for Revotek-LC group mean value (-0.000539 ±0.003 µm) followed by Jet tooth shade group mean value (-0.000478 ±0.001 µm) while the lowest roughness change was recorded for TempSpan group mean value (-0.0002 ±0.001 µm). The difference between groups was statistically non-significant. On the other hand, weight change results showed that the highest weight change was recorded for Jet tooth shade group mean value (-0.006717 ±0.0006 gr) followed by Revotek-LC group mean value (-0.00345 ±0.0021 gr) while the lowest weight change was recorded for TempSpan group mean value (-0.001167 ±0.0004 gr), and the difference between groups was statistically significant as indicated by ANOVA test followed by Tukey’s post-hoc test (p= 0.05). Conclusions: 1. There was no significant change in roughness of each tested interim restorative material before and after 3 months wear simulation cycles. 2. TempSpan and Revotek LC showed the highest wear resistance based on weight change measurements. 3. Jet tooth shade interim restorative material exhibit the lowest roughness change of enamel antagonist.

Comparative Study of Pulpal Responses to Pulpotomy with ProRoot MTA, RetroMTA, and TheraCal in Dogs' Teeth

IntroductionThis study was conducted to evaluate and compare pulpal responses to ProRoot MTA (Dentsply Tulsa Dental, Tulsa, OK), RetroMTA (Meta Biomed Co, Ltd, Seoul, Korea), and TheraCal (Bisco Inc, Schamburg, IL) in dog partial pulpotomy models. MethodsPartial pulpotomies were performed on 60 beagle teeth. The exposed pulp tissues were randomly capped with either ProRoot MTA (n = 15), RetroMTA (n = 15), TheraCal (n = 15), or interim restorative material as a negative control (n = 15). After 4 weeks, the teeth were extracted and processed for histologic and immunohistochemical examinations using osteocalcin and dentin sialoprotein. Calcific barrier formation, inflammatory reaction, and the odontoblastic layer were evaluated and scored in a blind manner. The areas of newly formed calcific barriers were measured for each group. ResultsIn most of the ProRoot MTA and RetroMTA specimens, continuous calcific barriers were formed, and the pulps contained palisading patterns in the odontoblastic layer that were free of inflammation. However, the TheraCal specimens had lower quality calcific barrier formation, extensive inflammation, and less favorable odontoblastic layer formation. Overall, areas of newly formed calcific barrier were higher in the ProRoot MTA and RetroMTA specimens than in the TheraCal specimens. Also, immunohistochemistry revealed that osteocalcin and dentin sialoprotein were more clearly visible in the ProRoot MTA and RetroMTA specimens than in the TheraCal specimens. ConclusionsRetroMTA could provide an alternative to ProRoot MTA. Both materials produced favorable pulpal responses that were similar in nature, whereas TheraCal produced less favorable pulpal responses.

Effect of liquid polishing materials on the stainability of bis-acryl interim restorative material in vitro

Statement of problemThe discoloration of interim restorations may negatively affect a patient’s perception of treatment. PurposeThe purpose of this study was to investigate the effect of liquid polishing materials on the color stability of bis-acryl interim restorative material. Material and methodsOne hundred twenty specimens (10×2 mm) of a bis-acryl interim restorative material were divided into 3 groups. Group CO (control) was not subjected to any liquid polishing material. Groups GC and BC were polished with 2 liquid polishing materials. The specimens were then divided into 4 subgroups (n=10) and stored for 24 hours at 37°C in different staining solutions: coffee, coffee with sugar, cola, and distilled water. The color of the specimens was measured at baseline and after immersion with a spectrophotometer by using the CIE L*a*b* system, and color changes (ΔE) were calculated. The means of color change for each specimen were analyzed by 2-way and 1-way ANOVA tests. Post hoc comparisons were made with the Tukey HSD and Tamhane T2 tests. ResultsThe application of liquid polishing materials significantly decreased the staining of autopolymerized bis-acryl interim restorative material (P<.01). Coffee with sugar resulted in higher ΔE values than coffee without sugar or cola. ConclusionsThe use of liquid polishing materials significantly decreased staining when compared with bis-acryl specimens without liquid polish. The presence of sugar in coffee increased color change compared with coffee without sugar for all groups evaluated.

Contribution of postpolymerization conditioning and storage environments to the mechanical properties of three interim restorative materials

Because polymer-based interim restorative materials are weak, even well-made restorations sometimes fail before the definitive restoration is ready for insertion. Therefore, knowing which fabrication procedures and service conditions affect mechanical properties is important, particularly over an extended period. The purpose of this study was to evaluate the effect of thermal treatment, surface sealing, thermocycling, storage media, storage temperature, and age on autopolymerizing poly(methylmethacrylate) and bis-acryl interim restorative materials. Outcome measures were flexural strength, Vickers surface microhardness, and impact strength. Flexural strength and microhardness of poly(methylmethacrylate) (Jet Acrylic) and 2 bis-acryl-composite resin (Protemp 3 Garant and Integrity) interim restorative materials were evaluated as affected by storage media, storage temperature, storage time, thermocycling, postpolymerization thermal treatment, or application of a surface sealer. In total, 2880 beam specimens (25×2×2 mm) were fabricated. Mechanical property analyses were made at 10 days, 30 days, 6 months, and 1 year after specimen preparation. Flexural strength was determined by using a 3-point bending test in a universal testing machine with a 1 kN load cell at a crosshead speed of 5.0 mm min(-1). Fracture specimens were recovered and used for determining Vickers microhardness. Measurements were made with a 0.1 N load and 15 second dwell time. Three microhardness measurements were made for each specimen, and the mean was used for reporting Vickers microhardness. Notched impact specimens (64×12.7×6.35 mm) were fabricated from Jet, Protemp 3 Garant, and Integrity interim restorative materials, yielding 288 impact specimens. Impact strengths were assessed at 10 days, 30 days, 6 months, and 1 year with a 2 J pendulum. The effects of the various experimental treatments were determined and rank ordered with analysis of variance, F ratios, and least square means differences Student t tests (α=.05). All experimental treatments investigated had significant effects on flexural strength, with material (P<.001) and thermocycling (P<.001) being dominant. Moreover, all experimental treatments investigated had a significant overall impact on Vickers microhardness with material (P<.001) and Palaseal glaze (P<.001) showing large effects. Material (P<.001) and age (P=.010) had a significant effect on impact strength. Mechanical properties of some interim polymeric materials can be improved by postpolymerization heat treatments or surface glazing. This procedure may extend the useful lifetime of some bis-acryl interim restorations.