• The Journal of Korean Academy of Prosthodontics
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• v.20 no.1
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• pp.25-32
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• 1982

An in vitro study was conducted to compare the bond strength of cements between Verabond coping and various cores. Fifty-four idential cores simulating maxillary central incisor prepared for PFM crowns were made. Eighteen samples were made with 20K cast gold, eighteen with Verabond, and eighteen with Adaptic. Samples were randomly divided into three groups, each consisting of six 20K cast gold, six verabond, and six Adaptic samples. The first group was cemented with zinc phosphate cement, the second group with poly-carboxylate cement, and the third group with glass ionomer cement. Constant finger pressure was applied for cementation. The sample were then stored at $37^{\circ}C$ in distilled water bath for 24 hours. The tensile strength test was performed on an Instron Universal test machine with crosshead speed of 0.05cm/min and the results compared statistically. Results of the study showed that: 1. A significant difference of bond strength was observed with different types of dental cements and core materials. 2. With gold core, zinc phosphate cement was stronger than both the polycarboxylate cement and glass ionomer cement, which did not differ in bond strength. 3. With base-metal core, zinc phosphate cement showed the highest bond strength and was followed by polycarboxylate cement and glass ionomer cement. 4. With composite resin core, zinc phosphate cement showed the highest bond strength and was followed by glass ionomer cement and polycarboxylate cement. 5. The base-metal core (Verabond core) privided the highest retention of all core materials.

• The Journal of Korean Academy of Prosthodontics
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• v.37 no.4
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• pp.465-473
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• 1999

Bond strength of luting cements to dentin is a critical consideration for success of complete cast crowns. This study was performed to evaluate the relationship between surface characteristics of teeth prepared for complete cast crowns and retention of cemented restorations. Eighty artificial crowns were cast for standardized complete crown tooth preparations accomplished with the use of a special device on recently extracted human teeth. Coarse diamond(#102R, Shofu) and superfine finishing diamond(#SF102R, Shofu) burs of similar shape were used. Crowns in each group were randomly subdivided into few subgroups of 10 for luting cements selected for this study: zinc phosphate cement (FLECK' S), polycarboxylate cement (Poly-F), rein-forced glass ionomer cement (Fuji PLUS). and adhesive resin cement (Panavia 21). Retention was evaluated by measuring the tensile load required to dislodge the artificial crown from tooth preparations with an Instron testing machine, and analysed by one-way ANOVA and Student's t-test. The obtained results were as follows ; 1. When tooth preparation was done with coarse diamond bur, retentive force was diminished in order of Panavia 21 Fuji PLUS, FLECK'S, and Poly-F. Retentive forces showed the significant difference between Fuji PLUS group and FLECK'S group(p<0.001). 2. When tooth preparation was done with superfine diamond bur, retentive force was diminished in order of Fuji PLUS, Panavia 21, FLECK'S, and Poly-F. Retentive forces showed the significant difference between Panavia 21 group and FLECK'S group(p<0.001). 3. Retentive force in coarse tooth surfaces was significantly higher than that in superfine tooth surface with all luting cements(p<0.001), and cement residues were almost retained with-in the cast crown in all groups.

• Journal of Dental Rehabilitation and Applied Science
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• v.22 no.3
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• pp.231-242
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• 2006

Statement of problem: The sealing of the opened dentinal tubules that follows the tooth preparation for the prosthodontic restoration is considered as clinical process to reduce postoperative sensitivity. Purpose: This study investigated the effect of desensitization treatment on shear bond strength of luting cements. Materials and Method: Total 80 dentin specimens were divided into two groups according to the kinds of luting cements. Each groups was further divided into 4 subgroups with AQ $bond^{(R)}$, $Saforide^{(R)}$, Diode laser $MDL-10^{(R)}$ application and without desensitization treatment. After desensitization treatment application, Ni-Cr specimens were luted to dentin surface with Fuji $CEM^{(R)}$ and $Panavia-F^{(R)}$. Specimens were placed in distilled water at $37^{\circ}C$ for 24 hours and shear bond strength between metal and dentin was measured by a universal testing machine. Results: 1. In Fuji $CEM^{(R)}$ cemented groups, the combination of AQ $bond^{(R)}$ showed the greatest strength, followed by diode laser, no desensitizer treatment, and $Saforide^{(R)}$. Both AQ $bond^{(R)}$ and Diode laser groups had a significant difference than no desensitization treatment group and $Saforide^{(R)}$ group(p<0.05). 2. In $Panavia-F^{(R)}$ cemented groups, the combination of Diode laser showed the greatest strength, followed by AQ $bond^{(R)}$, $Saforide^{(R)}$, and No desensitization treatment. All desensitization treatment groups had a significant difference than no desensitization treatment group(p<0.05). 3. All $Panavia-F^{(R)}$ groups showed a significant higher shear bond strength than all Fuji $CEM^{(R)}$ groups(p<0.05). Conclusion: The results of this study showed possibility of bond strength increase after desensitization treatment. The application of desensitization treatments like AQ $bond^{(R)}$, $Saforide^{(R)}$, and Diode laser $MDL-10^{(R)}$ have advantages in exposed dentin surface after tooth prep.

• Journal of Dental Rehabilitation and Applied Science
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• v.25 no.1
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• pp.1-12
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• 2009

The objective of this study was to test the effects of crown material, cement type, the direction in which stress is applied and distribution of luting cement that might lead to cement microfracture using 2D Finite Element Method. Twenty three finite element models with a chamfer margin configuration were generated for a mandibular first molar. Crown models exhibited four crown materials: type 3 gold alloy, Ni-Cr alloy, ceramic and composite resin, and two luting cements: zinc phosphate and glass ionomer cements with a thicknesses of $70{\mu}m$. Modeled crowns were loaded axially or obliquely at unit load of 1 N. Areas and levels of stress concentrations within the cement were determined. Stress in the cement layer at the margins of crowns were higher than those in the area away from the margin. Stress under oblique loads were much higher than under axial load. The stiffer crown material produced higher stress and similarly, higher stress were found in cements with the greater Young's modulus.

• Journal of Dental Rehabilitation and Applied Science
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• v.28 no.2
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• pp.119-126
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• 2012

State of problem: Cement-retained implant-supported prostheses are routinely used in dentistry. The use of high strength cements has become more popular with the increasing confidence in the stability of the implant-abutment screw connection and the high survival rates of osseointegrated implants. No clinical data on retention of metal copings using CAD/CAM. To evaluate retention of metal copings using CAD/CAM system bonded to short titanium abutment with four different cements and compare retentive strength of metal copings with sandblasting or without sandblasting before cementation. Forty titanium abutment blocks were fabricated and divided into 4 groups of 10 samples each. Forty metal copings with occlusal hole to allow for retention testing were fabricated using CAD/CAM technology. The four cements were Fujicem(Fuji, Japan), Maxcem Elite(Kerr, USA), Panavia F2.0(Kurarary, Japan) and Superbond C&B(Sunmedical, Japan). The copings were cemented on the titanium abutment according to manufacture's recommendation. All samples were stored for 24h at 37oC in 100% humidity and tested for retention using universal testing machine(Instron) at a crosshead speed of 1.0mm/min. Force at retentive failure was recorded in Newton. The mode of failure was also recorded. Means and standard deviations of loads at failure were analyzed using ANOVA and Paired t-test. Statistical significance was set at P<0.05. Panavia F2.0 provided significantly higher retentive strength than Fujicem, Maxcem Elite(P<0.05). Sandblasting significantly increased bond strength(P<0.05). The mode of failure was cement remaining principally on metal copings. Within the limitation of this study, Panavia F2.0 showed significantly stronger retentive strength than Fujicem, Maxcem Elite(p<0.05). The Ranking order of the cements to retain the copings was Panavia F2.0, Fujicem = Maxcem Elite. Sandblasting significantly increased bond strength(P<0.05). The retentive strength of metal copings on implant abutment were influenced by surface roughness and type of cements.

• The Journal of Korean Academy of Prosthodontics
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• v.26 no.1
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• pp.23-30
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• 1988

An in vitro study was performed to compare the retentive value of cast post cemented with three commonly used cements and one composite resin. Twenty cast posts were made from twenty extracted lower premolars. The samples were randomly divided into four groups. The first group was cemented with zinc phosphate cement, the second group with polycarboxylate cement, the third group with glass-ionomer cement, and the fourth group with composite resin. The tensile load test was performed on an Instron testing machine with crosshead speed of 2 mm/min and the results were compared statistically. The results were as follows ; 1. The mean value of tensile break force of cemented cast post was 23.36Kg in case of zinc phosphate cement, 16.28Kg in case of polycarboxylate cement, 22.09Kg in case of glass-ionomer cement , and 26.88Kg in case of composite resin. 2. Retention was not significantly different among zinc phosphate cement, glass-ionomer cement and composite resin. 3. Polycarboxylate cement was found to be less retentive than zinc phosphate cement, glass-ionomer cement , and composite resin.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.24 no.1
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• pp.59-66
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• 1994

The radiopacity of six composite resins, three resin luting cements and ten filling materials were studied. The purpose was to obtain an indication of radiopacity value of different brands within each of these groups of materials and to show differences in radiopacities of filling materials and natural tooth structures. On radiographs, the optimal densities of standardized samples were determined by computer imaging system and radiopacity values of the materials were expressed in millimeter equivalent aluminum. Within the groups of materials studied, there was considerable variation in radiopacity. The composite resins of P-50, Z100 and Prisma AP.H displayed much higher radiopacities than aluminum. Panavia resin cement was shown to be similarly radiopaque to aluminum. Generally, the radiopacity of base and filling materials appeared to be higher than that of the enamel and dentin. If materials with substantial difference in radiopacity are used in combined applications for restorative treatment of teeth, lower radiopacity can interfere with the diagnosis and detection of gaps near the restoration.

• The Journal of Advanced Prosthodontics
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• v.7 no.3
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• pp.207-213
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• 2015

PURPOSE. The purpose of this study was to examine the abutment screw stability of screw- and cement-retained implant-supported dental prosthesis (SCP) after simulated cement washout as well as the stability of SCP cements after complete loosening of abutment screws. MATERIALS AND METHODS. Thirty-six titanium CAD/CAM-made implant prostheses were fabricated on two implants placed in the resin models. Each prosthesis is a two-unit SCP: one screw-retained and the other cemented. After evaluating the passive fit of each prosthesis, all implant prostheses were randomly divided into 3 groups: screwed and cemented SCP (Control), screwed and non-cemented SCP (Group 1), unscrewed and cemented SCP (Group 2). Each prosthesis in Control and Group 1 was screwed and/or cemented, and the preloading reverse torque value (RTV) was evaluated. SCP in Group 2 was screwed and cemented, and then unscrewed (RTV=0) after the cement was set. After cyclic loading was applied, the postloading RTV was measured. RTV loss and decementation ratios were calculated for statistical analysis. RESULTS. There was no significant difference in RTV loss ratio between Control and Group 1 (P=.16). No decemented prosthesis was found among Control and Group 2. CONCLUSION. Within the limits of this in vitro study, the stabilities of SCP abutment screws and cement were not significantly changed after simulated cement washout or screw loosening.

• Restorative Dentistry and Endodontics
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• v.39 no.3
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• pp.201-209
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• 2014

Objectives: This study evaluated the solubility, dimensional alteration, pH, electrical conductivity, and radiopacity of root perforation sealer materials. Materials and Methods: For the pH test, the samples were immersed in distilled water for different periods of time. Then, the samples were retained in plastic recipients, and the electrical conductivity of the solution was measured. The solubility, dimensional alteration, and radiopacity properties were evaluated according to Specification No. 57 of the American National Standards Institute/American Dental Association (ANSI/ADA). Statistical analyses were carried out using analysis of variance (ANOVA) and Tukey's test at a significance level of 5%. When the sample distribution was not normal, a nonparametric ANOVA was performed with a Kruskal-Wallis test (${\alpha}$ = 0.05). Results: The results showed that white structural Portland cement (PC) had the highest solubility, while mineral trioxide aggregate (MTA)-based cements, ProRoot MTA (Dentsply-Tulsa Dental) and MTA BIO ($\hat{A}$ngelus Ind. Prod.), had the lowest values. MTA BIO showed the lowest dimensional alteration values and white PC presented the highest values. No differences among the tested materials were observed in the the pH and electrical conductivity analyses. Only the MTA-based cements met the ANSI/ADA recommendations regarding radiopacity, overcoming the three steps of the aluminum step wedge. Conclusions: On the basis of these results, we concluded that the values of solubility and dimensional alteration of the materials were in accordance with the ANSI/ADA specifications. PCs did not fulfill the ANSI/ADA requirements regarding radiopacity. No differences were observed among the materials with respect to the pH and electrical conductivity analyses.

• Restorative Dentistry and Endodontics
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• v.43 no.3
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• pp.32.1-32.11
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• 2018

Objectives: This study evaluated the effects of a bleaching agent on the composition, mechanical properties, and surface topography of 6 conventional glass-ionomer cements (GICs) and one resin-modified GIC. Materials and Methods: For 3 days, the specimens were subjected to three 20-minute applications of a 37% $H_2O_2$-based bleaching agent and evaluated for water uptake (WTK), weight loss (WL), compressive strength (CS), and Knoop hardness number (KHN). Changes in surface topography and chemical element distribution were also analyzed by energy-dispersive X-ray spectroscopy and scanning electron microscopy. For statistical evaluation, the Kruskal-Wallis and Wilcoxon paired tests (${\alpha}=0.05$) were used to evaluate WTK and WL. CS specimens were subjected to 2-way analysis of variance (ANOVA) and the Tukey post hoc test (${\alpha}=0.05$), and KH was evaluated by one-way ANOVA, the Holm-Sidak post hoc test (${\alpha}=0.05$), and the t-test for independent samples (${\alpha}=0.05$). Results: The bleaching agent increased the WTK of Maxxion R, but did not affect the WL of any GICs. It had various effects on the CS, KHN, surface topography, and the chemical element distribution of the GICs. Conclusions: The bleaching agent with 37% $H_2O_2$ affected the mechanical and surface properties of GICs. The extent of the changes seemed to be dependent on exposure time and cement composition.