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Fatma ASHEIBI, Alison J.E. QUALTROUGH, Anthony MELLOR, Philip J. WITHE ...
2014 Volume 33 Issue 1 Pages
1-6
Published: January 30, 2014
Released on J-STAGE: February 01, 2014
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This study compares the effectiveness of ProTaper rotary files with ProTaper retreatment and K-files in the removal of Resilon or gutta percha (GP) from canals filled either by cold lateral condensation or thermal obturation using micro-CT. Ninety-six teeth were prepared using ProTaper files and allocated into four groups (
n=24): Group-1 was filled with GP/AH-Plus and Group-2 with Resilon/RealSeal using cold lateral condensation. Group-3 was filled with GP/AH-Plus and Group-4 with Resilon/RealSeal using System B and Obtura II. The roots were scanned by micro-CT. Each group was divided into two subgroups (
n=12): A, retreated using ProTaper files and B, using ProTaper retreatment and K-files. The roots were scanned to calculate the volume of the remaining material. With thermal obturation, roots filled with Resilon had significantly more remaining material than GP. Obturation using thermal technique resulted in significantly less remaining material than cold condensation except Resilon retreated using ProTaper retreatment and K-files.
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Stefano TETÈ, Vincenzo Luca ZIZZARI, Bruna BORELLI, Marianna DE COLLI ...
2014 Volume 33 Issue 1 Pages
7-15
Published: January 30, 2014
Released on J-STAGE: February 01, 2014
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Human gingival fibroblasts (HGFs) were cultured onto CAD/CAM zirconia (Group A), CAD/CAM zirconia after polishing (Group B), CAD/CAM lithium disilicate after polishing (Group C), and feldspathic ceramic (Group D) to evaluate their proliferation and adhesion potential. After 3 h, HGF adhesion was similar in all groups. Later, HGFs closely adhered to surfaces, particularly onto groups B, C and D, acquiring an elongated shape. Proliferation assay showed no differences in cell viability among the groups after 24 h, while significant increase was shown after 72 h in Groups B and C. After 24 h, similar Collagen I levels were found in all groups, while after 72 h Groups B and C revealed a deep reduction in respect to the 24 h level.
In vitro, HGF behavior may reflect variability in soft tissue response to different surface materials for prosthetic restorations, and support that polished zirconia is able to achieve a better integration
in vivo in respect to the other materials.
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Mariko HATTORI, Yuka I. SUMITA, Lovely MUTHIAH, Naohiko IWASAKI, Hidek ...
2014 Volume 33 Issue 1 Pages
16-20
Published: January 30, 2014
Released on J-STAGE: February 01, 2014
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This study evaluated the effects of the fabrication process on tensile bond strength between maxillofacial silicone elastomer and acrylic resin. A common maxillofacial silicone elastomer (VST-50), two primers (Sofreliner primer and R-SI-LINE Plasticbond), and two acrylic resins (Unifast III and Palapress Vario) were selected. Silicone elastomer between primed acrylic resin plates were polymerized using a metal flask mold or a flaskless stone mold. Bond strength of the specimens was measured by a tensile test and analyzed using two-way analysis of variance (ANOVA) with Tukey’s honest significant difference test. All fracture surfaces showed interfacial fracture. Both the fabrication process and the primer-acrylic resin combination affected bond strength, and two-way ANOVA indicated a significant interaction. Bond strength was generally greater when silicone elastomer was polymerized using a flaskless stone mold.
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Murat UNAL, Ihsan HUBBEZOGLU, Recai ZAN, Fatih OZNURHAN
2014 Volume 33 Issue 1 Pages
21-26
Published: January 30, 2014
Released on J-STAGE: February 01, 2014
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The present study aimed to compare post-aging microtensile values of fissure sealant(FS) containing amorphous calcium phosphate(ACP) with or without bonding after various enamel-etching methods. The buccal enamel surfaces of teeth were prepared and divided into five main groups according to enamel etching (Group 1; acid-etching, Group 2; air-abrasion, Group 3; 2W, Group 4; 3W, and Group 5; 4W of Er:YAG laser). Each main group was subdivided as with(Subgroup B) or without(Subgroup A) a bonding system. We applied FS-containing ACP to etched enamel surfaces. All specimens were aged by Thermocycling and water bath. We then measured microtensile bond strengths and analyzed data with two-way ANOVA and Tukey’s tests. We found a statistically significant difference between Group 1 and Group 2, between Subgroup B of Group 5 and Subgroups B of all other groups, and between Subgroups A and Subgroups B of all main groups (
p<0.01). Er:YAG laser-etching may be an alternative enamel etching method to acid-etching for ACP-containing FS.
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Kana MIYARA, Yoshio YAHATA, Yohsuke HAYASHI, Yusuke TSUTSUMI, Arata EB ...
2014 Volume 33 Issue 1 Pages
27-31
Published: January 30, 2014
Released on J-STAGE: February 01, 2014
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The purpose of this study was to investigate the influence of heat treatment on the mechanical properties of Ni-Ti file materials. Ni-Ti wire (1.00 mm ø) was processed into a conical shape with 0.30-mm diameter tip and 0.06 taper. Specimens were heated for 30 min at 300, 400, 450, 500 or 600°C. Non-heated specimens were used as controls. DSC, a cantilever-bending test and cyclic fatigue test were performed. Ms and Af for groups 400 and 450 were higher than those for others (
p<0.05). The load/deflection ratios of groups 400, 450 and 500 were lower than that of group 600 (
p<0.05). The bending load values at 2.0-mm deflection of groups 400, 450 and 500 were lower than those of group 300 and the control group (
p<0.05). The NCFs of groups 400, 450 and 500 exceeded that of group 600(
p<0.05). Changes in flexibility with heat treatment could improve the cyclic fatigue properties of Ni-Ti instruments.
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Ji Hye KIM, Han Cheol CHOE, Mee Kyoung SON
2014 Volume 33 Issue 1 Pages
32-38
Published: January 30, 2014
Released on J-STAGE: February 01, 2014
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This study aimed to evaluate the tensile and transverse bond strength of chairside reline resins (Tokuyama Rebase II, Mild Rebaron LC) to a thermoplastic acrylic resin (Acrytone) used for non metal clasp denture. The results were compared with those of a conventional heat polymerized acrylic resin (Paladent 20) and a thermoplastic polyamide resin (Biotone). The failure sites were examined by scanning electron microscopy to evaluate the mode of failure. As results, the bond strength of reline resins to a thermoplastic acrylic resin was similar to the value of a conventional heat polymerized acrylic resin. However, thermoplastic polyamide resin showed the lowest value. The results of this study indicated that a thermoplastic acrylic resin for non metal clasps denture allows chairside reline and repair. It was also found that the light-polymerized reline resin had better bond strength than the autopolymerizing reline resin in relining for a conventional heat polymerized acrylic resin and a thermoplastic acrylic resin.
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Hajime KANEKO, Hodaka SASAKI, Shinya HONMA, Tohru HAYAKAWA, Mitsunobu ...
2014 Volume 33 Issue 1 Pages
39-47
Published: January 30, 2014
Released on J-STAGE: February 01, 2014
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The influence of a thin carbonate-containing hydroxyapatite (CA) coating to tetragonal zirconia polycrystal (TZP) on osteoblastlike cell response was investigated. TZP disks were subjected to blasting and acid etching. Thin CA coatings were deposited by the molecular precursor method (TZP-CA). Initial cell adhesion of mouse osteoblast-like cells MC3T3-E1 was enhanced, and marked progress of actin filaments was observed on TZP-CA compared to on TZP. After 3, 5 or 7 days, cell proliferation on TZP-CA was significantly higher than that on TZP. Alkaline phosphatase activity was slightly lower on TZP-CA than on TZP at 7 days, and no difference was observed at 14 or 21 days. At 28 days incubation, collagenous fibers with mineral precipitants accompanied by phosphorous and amino groups were observed. These results indicate that thin CA coating with molecular precursor method offers promise as a means of enhancing cell response, particularly initial adhesion and proliferation of MC3T3-E1 cells.
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Masayoshi IINO, Ryosuke MURAYAMA, Yutaka SHIMAMURA, Hiroyasu KUROKAWA, ...
2014 Volume 33 Issue 1 Pages
48-53
Published: January 30, 2014
Released on J-STAGE: February 01, 2014
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The purpose of this study was to determine the effect of PRG filler extraction solution on the demineralization of enamel using optical coherence tomography (OCT). Bovine enamel was treated with lactic acid buffer solution and then placed in artificial saliva (De group). In the second group, specimens were stored in PRG filler extraction solution followed by immersion in lactic acid buffer solution (PRG group). In the control group, specimens were simply stored in artificial saliva. From the OCT image, the peak intensity (dB) and width at (1/e
2) were obtained, and the integrated value was calculated. The data were analyzed using Tukey-Kramer tests (α=0.05). There was a slight but significant increase in the integrated value observed for the control group, and a slight but significant decrease in the value observed for the De group. For the PRG group, integrated values were doubled after seven days from the start of the experiment.
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Pong PONGPRUEKSA, Pisol SENAWONGSE, Nataya VONGPHAN
2014 Volume 33 Issue 1 Pages
54-58
Published: January 30, 2014
Released on J-STAGE: February 01, 2014
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The effect of tubule orientation of dentin on the elastic modulus of resin-infiltrated dentin was evaluated. Rectangular cylindricalshaped dentin specimens with their long axis parallel to and perpendicular to dentinal tubules were prepared from extracted premolars. Twenty-five mineralized specimens of each orientation were evaluated. The remaining specimens were then demineralized. The demineralized specimens and the demineralized following by infiltration with one of these adhesives; Optibond Solo Plus, Single Bond 2 or Prime & Bond NT, from each orientation were evaluated (25 specimens per group). The tubular orientation only affected the elastic modulus of mineralized dentin. The highest elastic modulus was observed for the mineralized dentin when the tensile force was applied parallel to the direction of tubules. The elastic modulus of demineralized dentin was the lowest. The adhesive resins increased the elastic modulus of demineralized dentin, but the differences among the three were insignificant.
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Ljubisa MARKOVIC, Rainer Andreas JORDAN, Marie-Claire GLASSER, Wolfgan ...
2014 Volume 33 Issue 1 Pages
59-63
Published: January 30, 2014
Released on J-STAGE: February 01, 2014
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The aim of this study was to use a non-tactile optical measurement system to assess the effects of three bleaching agents’ concentrations on the surface roughness of dental restoration materials. Two composites (Grandio, Venus) and one glass ionomer cement (Ketac Fil Plus) were used in this
in vitro study. Specimens were treated with three different bleaching agents (16% and 22% carbamide peroxide (Polanight) and 38% hydrogen peroxide (Opalescence Boost)). Surface roughness was measured with an optical profilometer (Infinite Focus G3) before and after the bleaching treatment. Surface roughness increased in all tested specimens after bleaching treatment (
p<0.05). Our
in vitro study showed that dental bleaching agents influenced the surface roughness of different restoration materials, and the restoration material itself was shown to have an impact on alteration susceptibility. There seemed to be no clinical relevance in case of an optimal finish.
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Neda NAGHAVI, Jamileh GHODDUSI, Hamid R. SADEGHNIA, Elham ASADPOUR, Sa ...
2014 Volume 33 Issue 1 Pages
64-69
Published: January 30, 2014
Released on J-STAGE: February 01, 2014
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Mineral trioxide aggregate (MTA) has shown good biocompatibility in several studies. In the present study, the genotoxic and cytotoxic effects of calcium enriched mixture (CEM) were evaluated compared with MTA using MTT and single-cell gel (comet) assays with serial ascending concentrations (0 to 1,000 µg/mL) of tested materials. Cytotoxicity data indicated that there is no significant difference between CEM and MTA at all concentrations except for the full concentration (1,000 µg/mL); CEM had lower cytotoxicity. Genotoxic effects were more evident with CEM at concentrations of 15.6 and 250 µg/mL; however, was less than that of MTA at concentrations of 500 and 1,000 µg/mL. The cytotoxicity and genotoxicity effects of the two experimental groups generally increased with consistency. Under the conditions of this study, CEM is biocompatible in terms of cyto- and genotoxicity. It appears to be an alternative to MTA as an endodontic biomaterial offering several advantages.
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Masahiro SHIMOGISHI, Yusuke TSUTSUMI, Shinji KURODA, Motohiro MUNAKATA ...
2014 Volume 33 Issue 1 Pages
70-78
Published: January 30, 2014
Released on J-STAGE: February 01, 2014
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The purpose of the present study was to clarify the potentiality of acidic fluoride solution in treating peri-implantitis. We examined bactericidal activity of fluoride solution against periodontal pathogens; and evaluated the effects of fluoride on titanium, and the effects on cell proliferation and differentiation of rat bone marrow cells on the fluoride-treated titanium.
Aggregatibacter actinomycetemcomitans and
Porphyromonas gingivalis were used to determine minimal inhibitory concentration (MIC) and shorttime exposure. The cells were seeded on the titanium surface with or without fluoride treatment. Then, cellular proliferation, differentiation and mineral deposition were analyzed. The MIC values for
A. actinomycetemcomitans and
P. gingivalis were 225 and 900 ppm F
−, respectively. In short-time exposure test, both bacterial strains exhibited a significant decrease in a concentrationdependent manner. Cell proliferation and mineral deposition were significantly increased on the fluoride-treated surface. Within the limitation of this study, acidic sodium fluoride solution has the potentiality in treating peri-implantitis.
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Tool SRIAMPORN, Niyom THAMRONGANANSKUL, Chumphol BUSABOK, Sushit POOLT ...
2014 Volume 33 Issue 1 Pages
79-85
Published: January 30, 2014
Released on J-STAGE: February 01, 2014
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The surface morphology and crystal structure change of dental zirconia after hydrofluoric acid (HF) etching were evaluated. Four groups of sintered zirconia specimens were 1) control group, 2) immersion in 9.5%HF at 25
oC for 1, 2, 3, or 24 h, 3) immersion in 9.5%HF at 80
oC for 1, 3, 5, or 30 min and 4) immersion in 48%HF at 25
oC for 30 or 60 min. The specimens were evaluated under SEM and XRD. The SEM analysis revealed changes in surface topography for all the HF-etched zirconia specimens. The irregularities surface increased with increasingly longer immersion times and higher etching solution temperatures. The XRD analysis of the HFetched zirconia specimens revealed the presence of a crystalline monoclinic phase along with a tetragonal form. It was concluded HF can etch dental zirconia ceramic, creating micro-morphological changes. Tetragonal-to-monoclinic phase transformation was induced on the etched zirconia surface.
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Nicolas REY, Nacer BENBACHIR, Tissiana BORTOLOTTO, Ivo KREJCI
2014 Volume 33 Issue 1 Pages
86-91
Published: January 30, 2014
Released on J-STAGE: February 01, 2014
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In this study, we evaluated
in vitro the staining susceptibility of an infiltration resin (Icon, DMG, Hamburg, Germany) and compared it with several marketed bonding systems. Fifty 1-mm-thick disk-shaped specimens were prepared for Icon and for each bonding material. Initial specimen color was assessed by a spectrophotometer. Specimens in each group were then randomly divided into five sub-groups and stored in an incubator at 37˚C in the dark for 60 days. Groups 4 and 5 were used as negative controls by being stored dry and in tap water respectively. Test groups were stored in (1) coffee, (2) tea, or (3) red wine. After 60 days of storage, new spectrophotometric measurements were performed and
dE (color difference) was calculated to determine color change. Icon showed higher staining susceptibility. The clinician should be aware of the staining potential of infiltration resins over time.
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Nevin COBANOGLU, Bora OZTURK, Abdulkadir SENGUN, Ali Riza CETİN, Fusun ...
2014 Volume 33 Issue 1 Pages
92-97
Published: January 30, 2014
Released on J-STAGE: February 01, 2014
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The purpose of this study was to investigate the dentin bond durability of a one-step, fluoride-containing, glass ionomer-based adhesive system, Reactmer Bond (RB), and that of a two-step, fluoride-containing, self-etch adhesive system, Clearfil Protect Bond (CPB). Enamel was removed from the occlusal surfaces of teeth, and flat dentin surfaces were entirely covered with a composite resin following the application of an adhesive material (
n=10). After specimens were sectioned into rectangular sticks of 0.87±0.03 mm
2, the sticks were randomly assigned into two accelerated aging time period groups: 1 week or 1 year. Microtensile bond strengths were determined. Bond strength of RB increased significantly after 1 year (1 week=27.80±10.57 MPa
versus 1 year=36.93±14.38 MPa) (
p<0.05). In contrast, there was no significant difference in bond strength between the two time periods for CPB (1 week=51.74±17.8 MPa
versus 1 year=56.03±18.85 MPa) (
p>0.05). Both fluoride-containing adhesives seemed to demonstrate reliable bonding performance after 1 year of accelerated aging in water.
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Jian-min HAN, Guang HONG, Kentaro HAYASHIDA, Takeshi MAEDA, Hiroshi MU ...
2014 Volume 33 Issue 1 Pages
98-103
Published: January 30, 2014
Released on J-STAGE: February 01, 2014
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To investigate the effect of composition on the initial viscosity and adhesive strength between denture adhesives and the denture base. Two types of water-soluble polymers (methoxy ethylene maleic anhydride copolymer [PVM-MA] and sodium carboxymethyl cellulose [CMC]) were used. Samples were divided into three groups. Group 1 contained only PVM-MA; Group 2 contained only CMC; and Group 3 contained PVM-MA and CMC. The initial viscosity and adhesive strength were measured. For Group 1, the initial viscosity increased significantly as PVM-MA content increased. The adhesive strength of Group 1 lasted longer than Group 2. The adhesive strength of Group 3 varied greatly. The ratio of CMC and PVM-MA has a significant effect on the initial viscosity and adhesive strength of denture adhesives. Our results suggest that it is possible to improve the durability of a denture adhesive by combining different water-soluble polymers.
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Jeong-Kil PARK, Geun-Ho LEE, Jong-Hwa KIM, Mi-Gyoung PARK, Ching-Chang ...
2014 Volume 33 Issue 1 Pages
104-110
Published: January 30, 2014
Released on J-STAGE: February 01, 2014
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This study evaluated the polymerization shrinkage, flexural and compressive properties of low-shrinkage resin composites. For the study, four methacrylate-based and one silorane-based resin composites were light cured using three different light-curing units (LCUs) and their polymerization shrinkage, flexural (strength (FS) and modulus (FM)) and compressive (strength (CS) and modulus (CM)) properties were evaluated. Data were statistically analyzed using ANOVA and a
post-hoc Tukey test. The polymerization shrinkage ranged approximately 7.6–14.2 μm for 2-mm thick specimens depending on the resin product and LCU. Filtek LS showed the least shrinkage while the rest shrank approximately 13.2–14.2 μm. However, Filtek LS showed the greatest shrinkage difference for the used LCUs. FS and CS of the tested specimens ranged 96.2–152.1 MPa and 239.2–288.4 MPa, respectively, depending on the resin product and LCU. The highest and lowest FS and FM were recorded for the methacrylate-based resin composites. Among the specimens, Filtek LS showed the lowest CS and CM.
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Setsuo SAITOH, Takashi NEZU, Kaori SASAKI, Masayuki TAIRA, Hiroyuki MI ...
2014 Volume 33 Issue 1 Pages
111-117
Published: January 30, 2014
Released on J-STAGE: February 01, 2014
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A new method to enhance the biofunctionalization of Ti materials was developed by the immersion of Au-sputtered titanium plates into a solution of alkanethiol with a carboxy group end (HS-C
11-COOH). X-ray photoelectron spectroscopy (XPS) analysis showed that the gold content increased with the Au sputtering time and reached over 98 at% after 100 s. The content of the characteristic alkanethiol elements (S, C, and O) in the immersed Ti specimens increased with the Au sputtering time, which indicates that the binding of alkanethiol molecules is enhanced by the Au modification on the Ti surface. Qualitative analysis of XPS (Au-S, COO
−, and OH
− species) and FTIR spectra (peaks assignable to an aliphatic carboxylic acid) for the sample after immersion also supported this. A strong positive correlation between the S and Au content confirms that Au sputtering is an effective method to control the alkanethiol treatment of Ti substrates.
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Ken KAKINO, Kazuhiko ENDO, Masanori HASHIMOTO, Kunihiko FURUTA, Hiroki ...
2014 Volume 33 Issue 1 Pages
118-124
Published: January 30, 2014
Released on J-STAGE: February 01, 2014
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Three types of metal specimens (ring-shaped, plate-shaped, and a simulated anterior arch) for distortion observations were made from Au-Ag-Pd-Cu alloy. Distortion due to polymerization shrinkage and thermal contraction of a heat-curing acrylic resin containing 4-META (4-methacryloyloxyethyl trimellitate anhydride, 4-META resin) could be visualized for the ring-shaped specimen, which showed increasing distortion of the metal frame upon adhesion of the resin to the outer metal surface. Distortion of the plateshaped specimen adhering to 4-META resin decreased with increasing thickness of the cured resin. The distortion of the metal frame simulating an anterior arch of a six-unit bridge with a facing composite resin showed that the curvature of the metal frame was larger after curing of the facing composite resin. However, it recovered most of its original curvature with an associated increase in the number of cracks between the crowns after trimming the resin to a tooth profile.
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Lili TIAN, Ce PENG, Ying SHI, Xuan GUO, Bo ZHONG, Juanjuan QI, Guanhon ...
2014 Volume 33 Issue 1 Pages
125-132
Published: January 30, 2014
Released on J-STAGE: February 01, 2014
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The occlusion of dentinal tubules is considered to be an effective strategy to treat dentin hypersensitivity. This
in vitro study introduced mesoporous silica nanoparticles (MSNs) for tubular occlusion to achieve deeper sealing. Further, MSNs with independently encapsulated calcium and phosphates (as calcium and phosphate sources) (Ca
2+/PO
43−@MSNs) were introduced to achieve improved efficacy of tubular occlusion and remineralization. MSNs or Ca
2+/PO
43−@MSNs were proportionally mixed with distilled water to make their respective desensitizing slurries, which were used to treat dentin surfaces. The efficacy of tubular occlusion was evaluated using scanning electron microscopy (SEM) images and an image analyzer, and compared with that achieved with Green-Or™ —a commonly used densitizer. The results demonstrated that both MSNs and Ca
2+/PO
43−@MSNs almost completely occluded dentinal tubules and formed a deeper seal which penetrated about 105 μm deep into the dentinal tubules. Significant differences in tubular occlusion were observed between Green-Or™ densitizer and MSNs or Ca
2+/PO
43−@MSNs. The novel MSNs-based nanomaterials showed great potential as a treatment option for dentin hypersensitivity.
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Yuya ASAKAWA, Hidekazu TAKAHASHI, Naohiko IWASAKI, Masahiro KOBAYASHI
2014 Volume 33 Issue 1 Pages
133-140
Published: January 30, 2014
Released on J-STAGE: February 01, 2014
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The aim of the present study was to characterize the effects of the ultraviolet light (UV) irradiation period on the bond strength of fiber-reinforced composite (FRC) posts to core build-up resin. Three types of FRC posts were prepared using polymethyl methacrylate, urethane dimethacrylate, and epoxy resin. The surfaces of these posts were treated using UV irradiation at a distance of 15 mm for 0 to 600 s. The pull-out bond strength was measured and analyzed with the Dunnett’s comparison test (α=0.05). The bond strengths of the post surfaces without irradiation were 6.9 to 7.4 MPa; those after irradiation were 4.2 to 26.1 MPa. The bond strengths significantly increased after 15 to 120-s irradiation. UV irradiation on the FRC posts improved the bond strengths between the FRC posts and core build-up resin regardless of the type of matrix resin.
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Xiu-Yin ZHANG, Xin-Jing ZHANG, Zhuo-Li HUANG, Bang-Shang ZHU, Rong-Ron ...
2014 Volume 33 Issue 1 Pages
141-146
Published: January 30, 2014
Released on J-STAGE: February 01, 2014
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The aim of this study was to investigate the hybrid effects of ZrO
2 nanoparticles (nano-ZrO
2) and aluminum borate whiskers (ABWs) on flexural strength and surface hardness of denture base resin, polymethyl methacrylate (PMMA). Both nano-ZrO
2 and ABWs were modified by silane coupling agent (Z6030) before being mixed with PMMA. Various amounts of silanized nano-ZrO
2 and ABWs were mixed with PMMA to prepare ZrO
2-ABW/PMMA composites. Flexural strength and surface hardness were evaluated using three- point bending test and Vickers hardness test respectively. Fractured surfaces were also observed by scanning electron microscopy (SEM). The mechanical behaviors of silanized ZrO
2-ABW/PMMA composites were significantly improved. Flexural strength reached a maximum value of 108.01±5.54 MPa when 2 wt% of nano-ZrO
2 was mixed with ABWs at a ZrO
2/ABW ratio of 1:2, amounting to an increase of 52% when compared with pure PMMA. Surface hardness achieved a maximum value of 22.50±0.86 MPa when 3 wt% of nano-ZrO
2 was mixed with ABWs at the same ZrO
2/ABW ratio, which was an increase of 27% when compared with pure PMMA.
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