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1.
The Journal of Korean Academy of Prosthodontics ; : 140-145, 2016.
Artigo em Coreano | WPRIM | ID: wpr-219803

RESUMO

Excessive occlusal wear causes loss of tooth structure, occlusal plane disharmony, impaired function and esthetic problems. Although the decrease of occlusal vertical dimension may be compensated by the growth of alveolar bone and tooth eruption, minimal increase of occlusal vertical dimension may be required for esthetics and retention of prosthesis. In this case, a 44-year-old male patient visited Seoul National University Dental Hospital with chief complaint of severe tooth wear and shade disharmony. Based on assessment of diagnostic wax-up, 3 mm increase of occlusal vertical dimension was determined. Removable occlusal splint and interim prosthesis was used to ascertain patient's comfort and adaptation. After the adaptation period, definitive prosthesis fabricated with full-contour monolithic zirconia were delivered and the patient was recommended to wear a nightguard device for prosthesis protection. This report presents a case of full mouth rehabilitation with the elevation of patient's occlusal vertical height, resulting in satisfactory esthetics and functions.


Assuntos
Adulto , Humanos , Masculino , Oclusão Dentária , Dentição , Estética , Reabilitação Bucal , Boca , Placas Oclusais , Próteses e Implantes , Seul , Dente , Atrito Dentário , Erupção Dentária , Desgaste dos Dentes , Dimensão Vertical
2.
The Journal of Korean Academy of Prosthodontics ; : 35-40, 2016.
Artigo em Coreano | WPRIM | ID: wpr-122205

RESUMO

The maxillary defects lead to anatomical and functional deformity of the maxillofacial region. As far as functions are concerned, such defects can produce difficulty in speech, mastication, and deglutition. Obturator prostheses play a very important role in functional recovery for post-maxillectomy patients. To achieve rigidity of the obturator, appropriate retention should be given, and the weight of the prosthesis be reduced. There are two types of hollow bulb obturator: open and closed. A closed type has many advantages. Nevertheless, some problems, including complexity of fabrication and water leakage into the bulb, have the closed hollow obturator not be widely used. The one-step polymerization technique described in this case overcomes the shortcomings by easily constructing a small hollow bulb with two thermoplastic resin sheets.


Assuntos
Humanos , Anormalidades Congênitas , Deglutição , Mastigação , Polimerização , Polímeros , Próteses e Implantes , Reabilitação , Água
3.
The Journal of Advanced Prosthodontics ; : 37-42, 2016.
Artigo em Inglês | WPRIM | ID: wpr-211468

RESUMO

PURPOSE: This study investigated the effect of amount of thickness reduction on color and translucency of dental monolithic zirconia ceramics. MATERIALS AND METHODS: One-hundred sixty-five monolithic zirconia specimens (16.3 mm x 16.3 mm x 2.0 mm) were divided into 5 groups (Group I to V) according to the number of A2-coloring liquid applications. Each group was then divided into 11 subgroups by reducing the thickness up to 1.0 mm in 0.1-mm increments (Subgroup 0 to 10, n=3). Colors and spectral distributions were measured according to CIELAB on a reflection spectrophotometer. All measurements were performed on five different areas of each specimen. Color difference (DeltaE*(ab)) and translucency parameter (TP) were calculated. Data were analyzed using one-way ANOVA and multiple comparison Scheffe test (alpha=.05). RESULTS: There were significant differences in CIE L* between Subgroup 0 and other subgroups in all groups. CIE a* increased (0.523.7) were obtained between Subgroup 0 and other subgroups. TP values generally increased as the thickness reduction increased in all groups (R2>0.89, P<.001). CONCLUSION: Increasing thickness reduction reduces lightness and increases a reddish, bluish appearance, and translucency of monolithic zirconia ceramics.


Assuntos
Cerâmica , Pigmentação em Prótese
4.
Journal of Periodontal & Implant Science ; : 152-155, 2015.
Artigo em Inglês | WPRIM | ID: wpr-10570

RESUMO

PURPOSE: This case report discusses the effect of a root submergence technique on preserving the periodontal tissue at the pontic site of fixed dental prostheses in the maxillary anterior aesthetic zone. METHODS: Teeth with less than ideal structural support for fixed retainer abutments were decoronated at the crestal bone level. After soft tissue closure, the final fixed dental prostheses were placed with the pontics over the submerged root area. Radiographic and clinical observations at the pontic sites were documented. RESULTS: The submerged roots at the pontic sites preserved the surrounding periodontium without any periapical pathology. The gingival contour at the pontic site was maintained in harmony with those of the adjacent teeth, as well as the overall form of the arch. CONCLUSIONS: The results of this clinical report indicate that a root submergence technique can be successfully applied in pontic site development with fixed dental prostheses, especially in the maxillary anterior esthetic zone.


Assuntos
Prótese Dentária , Prótese Parcial Fixa , Patologia , Periodonto , Dente
5.
The Journal of Korean Academy of Prosthodontics ; : 325-329, 2015.
Artigo em Coreano | WPRIM | ID: wpr-99572

RESUMO

PURPOSE: The aim of this study was to compare the film thicknesses of several resin cements as a function of time after mixing and to examine the effect of working time on the film thicknesses. MATERIALS AND METHODS: The film thickness (microm) of 4 resin cements (n=10), 1 composite resin (Panavia F 2.0), 3 self-adhesive resin (Clearfil SA luting, Zirconite, RelyX U200) cements was measured at 20-second intervals after mixing of the cements up to 200 seconds under a load of 50 N. Linear regression was fitted to verify the effect of working time on the film thickness of each cement. Data were compared to the working time recommended by manufacturers using Wilcoxon test (alpha=.05). RESULTS: All of the materials showed a positive linear correlation between the film thickness and working time. There was no statistically significant difference between the working time based on our results and the values recommended by the manufacturers even though there was a discrepancy between those two values. CONCLUSION: The film thickness of resin cements could increase with the increase of working time. Working time to meet the ISO standard of 50-microm maximum film thickness could be different from the manufacturer's recommended value.


Assuntos
Modelos Lineares , Cimentos de Resina , Resinas Sintéticas
6.
The Journal of Korean Academy of Prosthodontics ; : 312-316, 2014.
Artigo em Coreano | WPRIM | ID: wpr-201570

RESUMO

PURPOSE: The aim of this study was to compare the fracture toughness of currently available resin cements for zirconia restorations and evaluate the effect of water storage on fracture toughness of those resin cements. MATERIALS AND METHODS: Single-edge notched specimens (3 mm x 6 mm x 25 mm) were prepared from three currently available dual cure resin cements for zirconia restorations (Panavia F 2.0, Clearfil SA luting and Zirconite). Each resin cement was divided into four groups: immersed in distilled water at 37degrees C for 1 (Control group), 30, 90, or 180 days (n=5). Specimens were loaded in three point bending at a cross-head speed of 0.1 mm/s. The maximum load at specimen failure was recorded and the fracture toughness (K(IC)) was calculated. Data were analyzed using one-way ANOVA and multiple comparison Scheffe test (alpha=.05). RESULTS: In control group, the mean KIC was 3.41 +/- 0.64 MN.m(-1.5) for Panavia F, 2.0, 3.07 +/- 0.41 MN.m(-1.5) for Zirconite, 2.58 +/- 0.30 MN.m(-1.5) for Clearfil SA luting respectively, but statistical analysis revealed no significant difference between them. Although a gradual decrease of K(IC) in Panavia F 2.0 and gradual increases of KIC in Clearfil SA luting and Zirconite were observed with storage time, there were no significant differences between immersion time for each cement. CONCLUSION: The resin cements for zirconia restorations exhibit much higher K(IC) values than conventional resin cements. The fracture toughness of resin cement for zirconia restoration would not be affected by water storage.


Assuntos
Imersão , Cimentos de Resina , Resinas Sintéticas , Água
7.
The Journal of Korean Academy of Prosthodontics ; : 317-323, 2014.
Artigo em Coreano | WPRIM | ID: wpr-201569

RESUMO

Dentinogenesis Imperfecta, with a high incidence rate of 1 : 6 - 8000, is inherited by autosomal dominant genetic transmission. This dental disorder causes discoloration of the teeth and the enamel and dentin show hypoplastic or hypocalcified defects which lead to frequent fractures and rapid attrition. Therefore, timely treatment is necessary for the preservation of the remaining teeth. In this particular case, a 19-year-old patient suffering from Type 1 dentinogenesis imperfecta showed signs of brownish hued teeth with multiple fractures, a loss of vertical dimension, excessive interdental space in the maxillary anterior teeth, and a lack of 5 posterior teeth. To improve the esthetic appearance of the anterior teeth, the vertical dimension was increased. Resin caps were used to alleviate the difficulty of taking an impression of multiple teeth at once. Monolithic zirconia materials used in this case showed high fracture strength and the ability to mask the discoloration of the teeth and therefore, functionally and esthetically favorable results were achieved.


Assuntos
Humanos , Adulto Jovem , Esmalte Dentário , Dentina , Dentinogênese Imperfeita , Incidência , Máscaras , Reabilitação , Dente , Dimensão Vertical
8.
The Journal of Advanced Prosthodontics ; : 46-52, 2014.
Artigo em Inglês | WPRIM | ID: wpr-192395

RESUMO

PURPOSE: The aim of this study was to evaluate the interface accuracy of computer-assisted designed and manufactured (CAD/CAM) titanium abutments and implant fixture compared to gold-cast UCLA abutments. MATERIALS AND METHODS: An external connection implant system (Mark III, n=10) and an internal connection implant system (Replace Select, n=10) were used, 5 of each group were connected to milled titanium abutment and the rest were connected to the gold-cast UCLA abutments. The implant fixture and abutment were tightened to torque of 35 Ncm using a digital torque gauge, and initial detorque values were measured 10 minutes after tightening. To mimic the mastication, a cyclic loading was applied at 14 Hz for one million cycles, with the stress amplitude range being within 0 N to 100 N. After the cyclic loading, detorque values were measured again. The fixture-abutment gaps were measured under a microscope and recorded with an accuracy of +/-0.1 microm at 50 points. RESULTS: Initial detorque values of milled abutment were significantly higher than those of cast abutment (P.05). After cyclic loading, detorque values of cast abutment increased, but those of milled abutment decreased (P<.05). There was no significant difference of gap dimension between the milled abutment group and the cast abutment group after cyclic loading. CONCLUSION: In conclusion, CAD/CAM milled titanium abutment can be fabricated with sufficient accuracy to permit screw joint stability between abutment and fixture comparable to that of the traditional gold cast UCLA abutment.


Assuntos
Desenho Assistido por Computador , Articulações , Mastigação , Titânio , Torque
9.
The Journal of Advanced Prosthodontics ; : 259-265, 2014.
Artigo em Inglês | WPRIM | ID: wpr-86722

RESUMO

PURPOSE: The purpose of this study was to develop a dental image processing system using a three-dimensional (3D) camera and stereovision technology. The reliability of the system for measuring axial wall convergence angles was evaluated. MATERIALS AND METHODS: The new system predicted 3D coordinate points from 2D images and calculated distances and angles between points. Two examiners measured axial wall convergence angles for seven artificial abutments using a traditional tracing-based method (TBM) and the stereovision-based method (SVBM). Five wax abutment models of simplified abutment forms were made and axial wall convergence angles of wax models were measured by both methods. The data were statistically analyzed at the level of significance, 0.05. RESULTS: Intraclass correlation coefficients showed excellent intra-examiner and inter-examiner reliabilities for both methods. Bland-Altman plots and paired t-tests showed significant differences between measurements and true values using TBM; differences were not significant with SVBM. CONCLUSION: This study found that the SVBM reflected true angle values more accurately than a TMB and illustrated an example of 3D computer science applied to clinical dentistry.


Assuntos
Odontologia
10.
The Journal of Advanced Prosthodontics ; : 185-193, 2014.
Artigo em Inglês | WPRIM | ID: wpr-53945

RESUMO

PURPOSE: The purpose of this study was to evaluate the intra-rater reliability and inter-rater reliability of three different methods using a drawing protractor, a digital protractor after tracing, and a CAD system. MATERIALS AND METHODS: Twenty-four artificial abutments that had been prepared by dental students were used in this study. Three dental students measured the convergence angles by each method three times. Bland-Altman plots were applied to examine the overall reliability by comparing the traditional tracing method with a new method using the CAD system. Intraclass Correlation Coefficients (ICC) evaluated intra-rater reliability and inter-rater reliability. RESULTS: All three methods exhibited high intra-rater and inter-rater reliability (ICC>0.80, P<.05). Measurements with the CAD system showed the highest intra-rater reliability. In addition, it showed improved inter-rater reliability compared with the traditional tracing methods. CONCLUSION: Based on the results of this study, the CAD system may be an easy and reliable tool for measuring the abutment convergence angle.


Assuntos
Humanos , Desenho Assistido por Computador , Dente Suporte , Estudantes de Odontologia , Preparo Prostodôntico do Dente
11.
The Journal of Korean Academy of Prosthodontics ; : 82-89, 2014.
Artigo em Coreano | WPRIM | ID: wpr-86183

RESUMO

PURPOSE: The purpose of this study was to observe the change of viscoelastic properties of dental resin cements during polymerization. MATERIALS AND METHODS: Six commercially available resin cement materials (Clearfil SA luting, Panavia F 2.0, Zirconite, Variolink N, RelyX Unicem clicker, RelyX U200) were investigated in this study. A dynamic oscillation-time sweep test was performed with AR1500 stress controlled rheometer at 32degrees C. The changes in shear storage modulus (G'), shear loss modulus (G"), loss tangent (tan delta) and displacement were measured for twenty minutes and repeated three times for each material. The data were analyzed using one-way ANOVA and Tukey's post hoc test (alpha=0.05). RESULTS: After mixing, all materials demonstrated an increase in G' with time, reaching the plateau in the end. RelyX U200 demonstrated the highest G' value, while RelyX Unicem (clicker type) and Variolink N demonstrated the lowest G' value at the end of experimental time. Tan delta was maintained at some level and reached the zero at the starting point where G' began to increase. The tan delta and displacement of the tested materials showed similar pattern in the graph within change of time. The displacement of all 6 materials approached to zero within 6 minutes. CONCLUSION: Compared to other resin cements used in this study, RelyX U200 maintained plastic property for a longer period of time. When it completed the curing process, RelyX U200 had the highest stiffness. It is convenient for clinicians to cement multiple units of dental prostheses simultaneously.


Assuntos
Prótese Dentária , Plásticos , Polimerização , Polímeros , Cimentos de Resina , Resinas Sintéticas , Triacetonamina-N-Oxil
12.
The Journal of Advanced Prosthodontics ; : 219-225, 2013.
Artigo em Inglês | WPRIM | ID: wpr-181925

RESUMO

PURPOSE: Few studies have investigated the marginal accuracy of 3-unit zirconia fixed partial dentures (FPDs) fabricated by computer-aided design/computer-aided manufacturing (CAD/CAM) system. The purpose of this study was to compare the marginal fit of zirconia FPDs made using two CAD/CAM systems with that of metal-ceramic FPDs. MATERIALS AND METHODS: Artificial resin maxillary central and lateral incisors were prepared for 3-unit FPDs and fixed in yellow stone. This model was duplicated to epoxy resin die. On the resin die, 15 three-unit FPDs were fabricated per group (45 in total): Group A, zirconia 3-unit FPDs made with the Everest system; Group B, zirconia 3-unit FPDs made with the Lava system; and Group C, metal-ceramic 3-unit FPDs. They were cemented to resin dies with resin cement. After removal of pontic, each retainer was separated and observed under a microscope (Presize 440C). Marginal gaps of experimental groups were analyzed using one-way ANOVA and Duncan test. RESULTS: Mean marginal gaps of 3-unit FPDs were 60.46 microm for the Everest group, 78.71 microm for the Lava group, and 81.32 microm for the metal-ceramic group. The Everest group demonstrated significantly smaller marginal gap than the Lava and the metal-ceramic groups (P.05). CONCLUSION: The marginal gaps of anterior 3-unit zirconia FPD differed according to CAD/CAM systems, but still fell within clinically acceptable ranges compared with conventional metal-ceramic restoration.


Assuntos
Prótese Parcial Fixa , Incisivo , Cimentos de Resina , Zircônio
13.
The Journal of Advanced Prosthodontics ; : 92-97, 2013.
Artigo em Inglês | WPRIM | ID: wpr-14724

RESUMO

PURPOSE: All-ceramic crowns are subject to fracture during function. To minimize this common clinical complication, zirconium oxide has been used as the framework for all-ceramic crowns. The aim of this study was to compare the fracture strengths of two computer-aided design/computer-aided manufacturing (CAD/CAM) zirconia crown systems: Lava and Digident. MATERIALS AND METHODS: Twenty Lava CAD/CAM zirconia crowns and twenty Digident CAD/CAM zirconia crowns were fabricated. A metal die was also duplicated from the original prepared tooth for fracture testing. A universal testing machine was used to determine the fracture strength of the crowns. RESULTS: The mean fracture strengths were as follows: 54.9 +/- 15.6 N for the Lava CAD/CAM zirconia crowns and 87.0 +/- 16.0 N for the Digident CAD/CAM zirconia crowns. The difference between the mean fracture strengths of the Lava and Digident crowns was statistically significant (P<.001). Lava CAD/CAM zirconia crowns showed a complete fracture of both the veneering porcelain and the core whereas the Digident CAD/CAM zirconia crowns showed fracture only of the veneering porcelain. CONCLUSION: The fracture strengths of CAD/CAM zirconia crowns differ depending on the compatibility of the core material and the veneering porcelain.


Assuntos
Cerâmica , Colódio , Coroas , Porcelana Dentária , Dente , Zircônio
14.
The Journal of Advanced Prosthodontics ; : 187-197, 2013.
Artigo em Inglês | WPRIM | ID: wpr-14710

RESUMO

PURPOSE: The purpose of this study was to evaluate various core designs on stress distribution within zirconia crowns. MATERIALS AND METHODS: Three-dimensional finite element models, representing mandibular molars, comprising a prepared tooth, cement layer, zirconia core, and veneer porcelain were designed by computer software. The shoulder (1 mm in width) variations in core were incremental increases of 1 mm, 2 mm and 3 mm in proximal and lingual height, and buccal height respectively. To simulate masticatory force, loads of 280 N were applied from three directions (vertical, at a 45degrees angle, and horizontal). To simulate maximum bite force, a load of 700 N was applied vertically to the crowns. Maximum principal stress (MPS) was determined for each model, loading condition, and position. RESULTS: In the maximum bite force simulation test, the MPSs on all crowns observed around the shoulder region and loading points. The compressive stresses were located in the shoulder region of the veneer-zirconia interface and at the occlusal region. In the test simulating masticatory force, the MPS was concentrated around the loading points, and the compressive stresses were located at the 3 mm height lingual shoulder region, when the load was applied horizontally. MPS increased in the shoulder region as the shoulder height increased. CONCLUSION: This study suggested that reinforced shoulder play an essential role in the success of the zirconia restoration, and veneer fracture due to occlusal loading can be prevented by proper core design, such as shoulder.


Assuntos
Força de Mordida , Coroas , Porcelana Dentária , Planejamento de Prótese Dentária , Análise do Estresse Dentário , Análise de Elementos Finitos , Dente Molar , Ombro , Software , Dente , Zircônio
15.
The Journal of Advanced Prosthodontics ; : 296-304, 2013.
Artigo em Inglês | WPRIM | ID: wpr-77581

RESUMO

PURPOSE: The aim of this study was to evaluate the effect of polishing and glazing on the color and spectral distribution of monolithic zirconia. MATERIALS AND METHODS: Forty-five monolithic zirconia specimens (16.3 mm x 16.4 mm x 2.0 mm) were fabricated and divided into 5 groups according to the number of A2-coloring liquid applications (Group I to V). Each group was divided into 3 subgroups according to the method of surface treatments (n=3): N: no treatment; P: polishing; G: glazing. Color and spectral distribution of five different areas of each specimen were measured according to CIELAB color space in the reflectance mode relative to the standard illuminant D65 on a reflection spectrophotometer. Data were analyzed using one-way ANOVA followed by Tukey's HSD test, Pearson correlation and regression analysis (alpha=.05). RESULTS: There was a significant difference in CIE L* between Subgroup N and P, and in CIE b* between Subgroup P and G in each group. Spectral reflectance generally decreased in Subgroup P and G in comparison with Subgroup N. Color differences between Subgroup P and G were within the perceptibility threshold (DeltaE*ab0.88, P<.001). CONCLUSION: A perceptible color difference can be detected after polishing of monolithic zirconia. Polishing decreases the lightness, and glazing also decreases the lightness, but increases the yellowness of monolithic zirconia.


Assuntos
Polimento Dentário , Luz , Propriedades de Superfície , Zircônio
16.
The Journal of Advanced Prosthodontics ; : 162-169, 2012.
Artigo em Inglês | WPRIM | ID: wpr-166995

RESUMO

PURPOSE: Fracture of the veneering material of zirconia restorations frequently occurs in clinical situations. The purpose of this in vitro study was to compare the fracture strengths of zirconia crowns veneered with various ceramic materials by various techniques. MATERIALS AND METHODS: A 1.2 mm, 360degrees chamfer preparation and occlusal reduction of 2 mm were performed on a first mandibular molar, and 45 model dies were fabricated in a titanium alloy by CAD/CAM system. Forty-five zirconia copings were fabricated and divided into three groups. In the first group (LT) zirconia copings were veneered with feldspathic porcelain by the layering technique. In the second group (HT) the glass ceramic was heat-pressed on the zirconia coping, and for the third group (ST) a CAD/CAM-fabricated high-strength anatomically shaped veneering cap was sintered onto the zirconia coping. All crowns were cemented onto their titanium dies with Rely X(TM) Unicem (3M ESPE) and loaded with a universal testing machine (Instron 5583) until failure. The mean fracture values were compared by an one-way ANOVA and a multiple comparison post-hoc test (alpha=0.05). Scanning electron microscope was used to investigate the fractured interface. RESULTS: Mean fracture load and standard deviation was 4263.8+/-1110.8 N for Group LT, 5070.8+/-1016.4 for Group HT and 6242.0+/-1759.5 N for Group ST. The values of Group ST were significantly higher than those of the other groups. CONCLUSION: Zirconia crowns veneered with CAD/CAM generated glass ceramics by the sintering technique are superior to those veneered with feldspathic porcelain by the layering technique or veneered with glass ceramics by the heat-pressing technique in terms of fracture strength.


Assuntos
Ligas , Cerâmica , Colódio , Coroas , Porcelana Dentária , Elétrons , Vidro , Dente Molar , Titânio , Zircônio
17.
The Journal of Korean Academy of Prosthodontics ; : 1-7, 2011.
Artigo em Coreano | WPRIM | ID: wpr-94362

RESUMO

PURPOSE: The purpose of this study was to investigate the cutting efficiency of coarse grit diamond burs with air-turbine handpiece on natural tooth. MATERIALS AND METHODS: Four groups of coarse grit diamond bur were selected: Komet (A), Shofu (B), Premier (C), and Mani (D). The extracted maxillary central incisors were used, and ten cuts were made on each specimen, using the rotary diamond burs. The surface of each bur was measured at the upper, middle, and bottom of the bur with confocal laser scanning microscope and imaged with SEM. The data were analyzed with one-way ANOVA and t-test at the significance level of 0.05. RESULTS: The surface roughness was measured. At the A diamond bur, the Sa values were 52.93 microm, 48.32 microm, 46.79 microm, 45.06 microm, and 43.43 microm for control, test 1, 2, 3, and 4 respectively. The Sa values were 50.68 microm, 45.62 microm, 44.41 microm, 44.10 microm, and 42.46 microm for B diamond bur, 58.02 microm, 55.53 microm, 52.22 microm, 48.26 microm, and 45.36 microm for C diamond bur, and 50.11 microm, 46.73 microm, 45.46 microm, 42.58 microm, and 41.80 microm for D diamond bur. Surface roughness after each bur use showed significant changes, but no significant difference was found in surface roughness change between bur systems. CONCLUSIONS: Surface roughness in the same bur system showed significant differences after each tooth preparation. However no statistically significant differences were found in surface roughness between bur systems. The SEM images between control and test 4 showed the abraded particles.


Assuntos
Humanos , Diamante , Incisivo , Dente , Preparo do Dente
18.
The Journal of Korean Academy of Prosthodontics ; : 101-105, 2011.
Artigo em Coreano | WPRIM | ID: wpr-14165

RESUMO

PURPOSE: The purpose of this study was to assess the marginal fit of three-unit bridges produced using LAVA CAD/CAM (computer-aided design/computer-aided manufacturing) system and conventional PFG in vitro. MATERIALS AND METHODS: #11, 13 resin teeth were prepared on dentiform, then duplicated. Twenty resin models were fabricated, ten for PFG 3-unit bridges and ten for LAVA 3-unit bridges. Each bridge was cemented on the resin model. Marginal discrepancy was measured with stereoscopic microscope (Nikon DS-Fi 1, Nikon, Japan) at a magnification of x75. Independent t-test was done for the statistical analysis. RESULTS: The mean marginal discrepancy values and standard deviations of the PFG bridges was 97.1 +/- 18.7 microm for incisors, 76.6 +/- 21.8 microm for canines; that of the LAVA bridges was 90.4 +/- 26.7 microm for incisor, 110.2 +/- 30.2 microm for canines. The mean marginal discrepancy between PFG and LAVA for incisor did not show significant difference (P>.05). But for canine, the mean marginal discrepancy of PFG bridges was smaller than that of LAVA bridges (P<.05). CONCLUSION: The LAVA CAD/CAM 3-unit bridges and the PFG 3-unit bridges showed clinically acceptable marginal discrepancy.


Assuntos
Incisivo , Dente
19.
The Journal of Korean Academy of Prosthodontics ; : 114-119, 2011.
Artigo em Coreano | WPRIM | ID: wpr-14163

RESUMO

PURPOSE: The aim of this study was to investigate effect of specimen preparation method on the microtensile bond strength of veneering ceramic to zirconia core. MATERIALS AND METHODS: Cylindrical Lava zirconia block (3M ESPE, Seefeld, Germany) was cut into discs using a diamond disc. After sintering, the core specimens were placed in an adjustable mold and veneered with Lava ceram (3M ESPE, Seefeld, Germany). The disc shaped specimen of group 1 was cut into microbars (1x1x7 mm3) using a low speed diamond disc under water cooling (n = 15). The specimen of group 2 was cut into microbars (1.2x1.2x7 mm3) in the same way. Whereafter the microbars were trimmed (1x1x7 mm3) using a thick diamond disc under water cooling (n = 15). The microtensile bond strength was tested in a microtensile tester (Instron 8848, Instro(R) Co., Norwood, USA). Fractured microtensile specimens were analyzed under a stereomicroscope (MZ6, Leica Microsystems GmbH, Wetzlar, Germany) at magnification x30. RESULTS: The microtensile bond strength of group 1 (28.8 +/- 7.0 MPa) was significantly higher than group 2 (11.0 +/- 3.3 MPa) (P=.00). CONCLUSION: It appears advisable to avoid the trimming action, especially high strength ceramic specimens.


Assuntos
Cerâmica , Diamante , Fungos , Água , Zircônio
20.
The Journal of Korean Academy of Prosthodontics ; : 128-137, 2011.
Artigo em Coreano | WPRIM | ID: wpr-14161

RESUMO

PURPOSE: Resonance frequency analysis, Periotest, and removal torque (RT) test were known as the methods to assess implant stability. The results of these methods are affected by the bone condition, implant diameter and shape. The purpose of this study is to access the meaning and the correlationship of the resonance frequency analysis, Periotest and RT test in osseointegration simulated acrylic resin when the engaged bone thickness and peri-implant bone defect are changed. MATERIALS AND METHODS: To simulate osseointegration, the fixture was fixed to an aluminum mold with a screw. Acrylic resin powder and liquid were poured into the mold for polymerization. The engaged resin thickness with implant was controlled. Simulated cortical bone thicknesses were 1, 3, 5 and 10 mm. Additional 1, 3 and 5 mm peri-implant bone defects were simulated. Three types of implants were used; 4 mm diameter implants of straight shape, 4 mm diameter implants of tapered shape and 5 mm diameter implants of tapered shape. Five fixtures per each type were tested in respective bone condition. Resonance frequency analysis and Periotest were evaluated in all bone conditions. Peak removal torque was measured at simulated cortical bone thicknesses of 1 and 3 mm. The statistical analysis was performed with the Kruskal-Wallis test, Mann-Whitney U test, and Spearman test using a 95% level of confidence. RESULTS: With increasing engaged bone depth, the Implant Stability Quotient (ISQ) values increased and the Periotest values (PTVs) decreased (P<.001, P<.001). With increasing peri-implant bone defect, ISQ values decreased and PTVs increased (P<.001). When the diameter of implant increased, ISQ values increased and Periotest values (PTV) decreased (P<.001). There was a strong correlation between ISQ values and PTVs (r = -0.99, P<.001). Furthermore, the peak removal torque values had weak correlations with both ISQ values and PTVs (r = 0.52, P<.001 ; r = -0.52, P<.001). CONCLUSION: This study confirmed favorable implant stability with increasing engaged bone depth and implant diameter and decreasing peri-implant bone defect. ISQ values and PTVs showed strong correlation with each other and not with the peak removal torque values.


Assuntos
Alumínio , Fungos , Osseointegração , Polimerização , Polímeros , Torque
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