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Materials have been developed to reduce the chipping of ceramic veneer and improve the esthetics of anterior ceramic veneered restorations. However, studies of the effects of material and substructure design on fracture resistance are sparse.The purpose of this in vitro study was to investigate the fracture resistance of metal-ceramic (MC), zirconia-feldspathic porcelain (ZC), and zirconia-lithium disilicate (ZL) anterior restorations and evaluate the effect of material and substructure design.After preparing and scanning artificial maxillary central incisor teeth, titanium abutments and restoration specimens (n=90) were fabricated. MC, ZC, and ZL materials were prepared with substructure designs A (two-third coverage of the palatal surface) and B (one-third coverage of the palatal surface). After cementation, the specimens were thermocycled (10 000 cycles, 5 and 55 °C). Fracture load measurements, failure mode analysis, energy dispersive X-ray spectroscopy (EDS), line scan analysis, fractography, finite element analysis (FEA), and Weibull analysis were performed. Two-way ANOVA was used to identify the effects of material and substructure design on fracture load. One-way ANOVA was used to identify significant differences of fracture load (α=.05).MC and ZL showed significantly higher fracture load than ZC (P.05). MC_A showed a significantly higher fracture load than MC_B (P.05). ZC_A exhibited the lowest Weibull modulus. FEA revealed that the maximum principal stress occurred near the loading area of the veneer. ZL displayed the lowest maximum principal stress among all the materials.ZL and MC_A exhibited more favorable fracture resistance. The substructure design of MC, with increased metal coverage of the palatal surface, improved fracture resistance significantly.

Statement of problem How axial displacement may be affected by the mechanical properties and internal discrepancy of a cement-retained implant-supported prosthesis is unclear. Purpose The purpose of this in vitro study was to assess the difference in internal discrepancy and axial displacement according to the prosthesis material in cement-retained prostheses splinting nonparallel implants. Material and methods Computer-aided design and computer-aided manufacture (CAD-CAM) titanium abutments were fabricated for a vertically placed implant and a 15-degree tilted implant. Three types of prostheses, in zirconia, cobalt-chromium (Co-Cr) alloy, and polymethylmethacrylate resin (PMMA), were fabricated (n=10). The internal discrepancy between the CAD-CAM titanium abutment and the prosthesis was measured by using the replica technique. After luting with an interim cement, they were mounted in Type IV gypsum. The specimens were cyclic loaded, and axial displacement of the prosthesis was measured after 3, 10, 100, and 106 cycles. The internal discrepancy and cumulative axial displacement were assessed by using a 3-way analysis of variance and repeated measures analysis of variance (α=.05). Results The internal discrepancy of the prosthesis did not differ based on the prosthesis material (P=.869); however, it was significantly different based on the measurement location, with the occlusal discrepancy (224 ±29 μm) being greater than the axial discrepancy (21 ±10 μm) (P Conclusions Prostheses made with high-elastic moduli materials exhibited less axial displacement than PMMA prostheses, even though the internal discrepancy was not different. Moreover, vertically placed implants presented a greater axial displacement of the prosthesis than implants with angled placement.

Materials used for dental restorations should cause wear similar to that of natural teeth. Studies on the wear of dental alloys against monolithic zirconia are lacking.The purpose of this in vitro study was to compare the wear of Co-Cr, gold, and Ni-Cr alloys against monolithic zirconia of different surface roughness.Cylindrical monolithic zirconia specimens were prepared by a sintering process. Sintered zirconia was then polished to prepare 30 zirconia substrate specimens with a smooth surface (Ra0.1 μm) and 30 with a rough surface (3.5 μmRa4.5 μm). As antagonist specimens, 3 types of metal alloys (Co-Cr, gold, and Ni-Cr alloys) were used. Twenty cast crowns were prepared from each metal alloy in the shape of a maxillary premolar. For each alloy, 10 cast crowns were randomly selected to oppose the smooth-surface zirconia specimens and 10 to oppose the rough-surface zirconia specimens. A total of 6 wear test groups were formed. Wear tests were performed by using a mastication simulator at 240 000 mastication cycles. Wear on the antagonist specimens was measured by using a laser 3D scanner. After wear testing, antagonist and substrate specimens were inspected by using a scanning electron microscope (SEM). For statistical analysis of the data, the 2-way ANOVA and the Scheffé multiple comparison tests were used (α=.05).Of the 6 test groups, the gold alloy specimens opposed to rough-surface zirconia exhibited the most wear, while the Co-Cr alloy specimens opposed to smooth-surface zirconia exhibited the least wear (P.05). Rough-surface monolithic zirconia caused significantly more wear of the metal alloy specimens than did smooth-surface monolithic zirconia (P.01).Increased surface roughness of monolithic zirconia was associated with increased wear of the opposing dental alloy. When monolithic zirconia surface roughness was increased, wear of dental alloys increased most for gold alloys, followed by Ni-Cr, and then Co-Cr alloys.

PURPOSE To compare the effect of 3 tray designs and 3 commonly used impression materials on the displacement of flabby tissue during maxillary edentulous impression by superimposition of 3D digital models. MATERIALS AND METHODS Fifteen maxillary edentulous casts with simulated flabby tissue were fabricated by modifying a standard maxillary edentulous acrylic resin cast. Three types of impression trays were fabricated: trays with conventional relief, trays with additional relief, and trays with an open window. Three impression materials were tested: light-body polysulfide, light-body vinylpolysiloxane, and zinc oxide eugenol paste. For the analysis of tissue displacement during impression making, the test and control stone casts were scanned using a 3D laser scanner, and the 3D digital models were superimposed using metrology software. Statistical analyses were performed with an α = 0.05. RESULTS Negative deviations were recorded at the areas of the alveolar crest, posterior part of flabby tissue, and middle of the palate. On the other hand, a positive deviation was recorded at the area of the anterior part of flabby tissue. A significant difference in the displacement of flabby tissue was found when using different tray designs (p < 0.0001). The tray with the open window showed significantly low tissue displacement at the flabby tissue region. Depending on sites, the amount of flabby tissue displacement showed different significances by the different impression materials used (anterior part: p < 0.0001; alveolar crest: p = 0.097; posterior part: p < 0.0001). Conventionally relieved trays showed significantly higher values of displacement at the anterior part of flabby tissue (p < 0.0001), while trays with open windows showed similar values of displacement at all measuring points, and no significant differences among different impression materials were found (p = 0.104). CONCLUSIONS There were significant differences in the displacement of flabby tissue with different tray designs, especially with displacement occurring at the anterior and posterior parts of flabby tissue. Tray designs should be considered in order to make proper impressions when flabby tissue is present.

Zirconia prostheses show a high rate of retention loss, and more information is needed regarding the treatment of the intaglios of zirconia prostheses to improve the bond strength between zirconia and resin cement.The purpose of this in vitro study was to evaluate the retention of titanium abutments and zirconia prostheses treated with silica-containing glass-ceramic liners. The effect of the abutment convergence angle on retention force was also examined.Titanium abutments and zirconia copings (n=90) were fabricated with 3 different convergence angles (6, 12, and 24 degrees). Specimens were divided into 2 groups according to surface treatment: an airborne-particle-abraded control group and a group that was coated with a silica-containing glass-ceramic liner after airborne-particle abrasion (liner group). The thickness of the liner was measured, and the inner spacing of the zirconia coping was modified in the liner group. The coping was cemented, and the retention was evaluated with a tensile bond strength test by using a universal testing machine. Retention was analyzed by using a 2-way analysis of variance. Modes of failure were evaluated by examining the fracture surface. Elemental analysis of the interface was also performed.The liner group showed a significantly higher retention force for the zirconia prosthesis (P.05). Regardless of surface treatment, the retention force at a convergence angle of 6 degrees was higher than that at 24 degrees (P.05). The control group showed mostly adhesive type failures, whereas the liner group exhibited mostly mixed type failures.Silica-containing glass-ceramic liner treatment increased the retention compared with airborne-particle abrasion treatment alone. Tensile bond strength increased with decreasing abutment convergence angle.

PURPOSE To determine the effects of the total thickness and core/veneer thickness ratio of bilayered ceramics on their three-point flexural strength and translucency. MATERIALS AND METHODS Two groups of specimens were prepared with two different total thicknesses, 1.0 mm and 0.6 mm. These groups were divided into five and three subgroups with ten specimens each, respectively, having different core/veneer thickness ratios. Lithium disilicate was pressed on the zirconia surface using the "lost-wax technique." The translucency and three-point flexural strength were measured, and a one-way analysis of variance test (p < 0.05) was performed to determine whether the translucency and three-point flexural strength were affected by the total thickness and core/veneer thickness ratio of the specimens. RESULTS For the same total thickness, translucency decreased with a increase in the zirconia core proportion (p < 0.001). For the same core/veneer ratio, the translucency decreased with an increase in the total thickness (p < 0.001). If the zirconia thickness was less than half of the total thickness, the bilayered ceramic specimens containing zirconia cores and monolithic lithium disilicate specimens exhibited a similar translucency. The three-point flexural strength increased with the increasing proportion of zirconia; however, it did not change significantly with the total thickness. However, for the same total thickness, the flexural strengths of the bilayered ceramics were higher than those of the monolithic specimens. CONCLUSIONS At the same total thickness, increasing the zirconia core thickness decreased the translucency and increased the three-point flexural strength. Bilayered ceramic specimens with low zirconia ratios exhibited translucency similar to that of monolithic lithium disilicate ceramic but a higher flexural strength.

Statement of problem Little information is available for the strength of bonding between zirconia and lithium disilicate as affected by surface pretreatment methods. Purpose The purpose of this in vitro study was to investigate the shear bond strength (SBS) between zirconia core and lithium disilicate (LS 2 ) veneered ceramic after surface pretreatments. Material and methods Fully sintered yttrium oxide partially stabilized tetragonal zirconia (Y-TZP) disk specimens were fabricated from zirconia ceramic materials. Specimens were divided into 4 groups with surface pretreatments applied (the as-received group, the liner group, the airborne-particle abrasion group, and the airborne-particle abrasion-plus-liner group). After pressing LS 2 on a zirconia disk, shear force was applied perpendicular to the zirconia-LS 2 interface. Data were analyzed using 2-way ANOVA and Tukey test ( α =.05). For each group, the failure modes were measured by using optical microscopy, scanning electron microscopy, energy dispersive x-ray spectroscopy, and x-ray diffraction. Results Airborne-particle abrasion induced significantly lower interfacial strength between zirconia and lithium disilicate ( P 2 . The liner treatment significantly improved the adhesion between zirconia core and veneering LS 2 ( P airborne-particle abrasion-plus-liner group > airborne-particle abrasion group. The interfacial image of zirconia and LS 2 showed a fusion of crystal structure between the 2 materials. Some components of the silica-containing glass-ceramic liner led to an increase in SBS as diffusion occurred on the zirconia surface. Conclusions The bond strength between zirconia and veneering LS 2 was significantly increased by application of silica-containing glass-ceramic liner but was decreased with airborne-particle abrasion.

Purpose To evaluate the axial displacement of the implant-abutment assembly of different implant diameter after static and cyclic loading of overload condition. Materials and Methods An internal conical connection system with three diameters (O 4.0, 4.5, and 5.0) applying identical abutment dimension and the same abutment screw was evaluated. Axial displacement of abutment and reverse torque loss of abutment screw were evaluated under static and cyclic loading conditions. Static loading test groups were subjected to vertical static loading of 250, 400, 500, 600, 700, and 800 N consecutively. Cyclic loading test groups were subjected to 500 N cyclic loading to evaluate the effect of excessive masticatory loading. After abutment screw tightening for 30 Ncm, axial displacement was measured upon 1, 3, 10, and 1,000,000 cyclic loadings of 500 N. Repeated-measure ANOVA and 2-way ANOVA were used for statistical analysis (α = 0.05). Results The increasing magnitude of vertical load and thinner wall thickness of implant increased axial displacement of abutment and reverse torque loss of abutment screw (p < 0.05). Implants in the O 5.0 diameter group demonstrated significantly low axial displacement, and reverse torque loss after static loading than O 4.0 and O 4.5 diameter groups (p < 0.05). In the cyclic loading test, all diameter groups of implant showed significant axial displacement after 1 cycle of loading of 500 N (p < 0.05). There was no significant axial displacement after 3, 10, or 1,000,000 cycles of loading (p = 0.603). Conclusions Implants with O 5.0 diameter demonstrated significantly low axial displacement and reverse torque loss after the cyclic and static loading of overload condition.

Purpose The purpose of this study was to evaluate axial displacement in cement-retained prostheses using computer-aided design/computer-aided manufacturing (CAD/CAM) abutments with three different types of implant-abutment connections. Materials and methods CAD/CAM abutments made with two types of titanium blocks (made by the same manufacturer as the implant manufacturer and by a manufacturer with a patent for CAD/CAM abutment fabrication) were connected with three types of implant connections: external, internal butt, and internal conical connection. Titanium custom abutments and zirconia prostheses were fabricated using the CAD/CAM system for each specimen. The geometries and surface morphologies of CAD/CAM abutments and ready-made abutments were comparatively evaluated using scanning electron microscopy. Cemented prostheses on abutments were mounted on a universal testing machine and subjected to 250-N sine wave cyclic loads. Cumulative axial displacement was measured at loading cycles of 3, 10, 100, and 106 and analyzed by repeated measures analysis of variance (ANOVA). Results Surface geometries and morphologies of CAD/CAM abutments varied according to the implant-abutment connection and manufacturers of the titanium block. The internal conical connection exhibited the greatest axial displacement, while the external connection showed the lowest axial displacement. The CAD/CAM abutment made with a compatible titanium block exhibited a greater axial displacement than that exhibited by the abutment fabricated using a titanium block made by the implant manufacturer. Conclusion In implant connections with a vertical stop, axial displacement occurred primarily in the early loading period and was self-limited. However, long-term axial displacement can occur with internal conical connection implants. Therefore, in internal conical connection implants, axial displacement should be managed more carefully using a provisional restoration, with consideration of the abutment fabrication method.

Purpose: To evaluate the effect of implant coronal wall thickness on load-bearing capacity and screw joint stability. Materials and Methods: Experimental implants were customized after investigation of the thinnest coronal wall thickness of commercially available implant systems with a regular platform diameter. Implants with four coronal wall thicknesses (0.2, 0.3, 0.4, and 0.5 mm) were fabricated. Three sets of tests were performed. The first set was a failure test to evaluate load-bearing capacity and elastic limit. The second and third sets were cyclic and static loading tests. After abutment screw tightening of each implant, vertical cyclic loading of 250 N or static loading from 250 to 800 N was applied. Coronal diameter expansion, axial displacement, and removal torque values of the implants were compared. Repeated measures analysis of variance (ANOVA) was used for statistical analysis (α = .05). Results: Implants with 0.2-mm coronal wall thickness demonstrated significantly low load-bearing capacity and elastic limit (both P < .05). These implants also showed significantly large coronal diameter expansion and axial displacement after screw tightening (both P < .05). Greater vertical load and thinner coronal wall thickness significantly increased coronal diameter expansion of the implant, axial displacement of the abutment, and removal torque loss of the abutment screw (all P < .05). Conclusion: Implant coronal wall thickness of 0.2 mm produces significantly inferior load-bearing capacity and screw joint stability.

Purpose: The aim of this study was to evaluate correlations between denture satisfaction and various factors related to patients` and wearing dentures. Materials and Methods: Total 43 edentulous patients were recalled and they were wearing complete dentures fabricated more than one year ago. For patients` subjective assessment, the questionnaire based on the various literatures was developed and applied to patients for data acquisition. In addition, correlations were evaluated between subjective assessment and denture satisfaction score. For statistical analysis, Spearman correlation coefficient, multiple regression analysis, Mann-whitney U test and Kruskal-Wallis test were used to found out what the most considerable factors to denture satisfaction score (P

Purpose To investigate the stress distribution in an implant-abutment complex with a preloaded abutment screw by comparing implant-abutment engagement features using three-dimensional finite element analysis (FEA). Materials and methods For FEA modeling, two implants-one with a single (S) engagement system and the other with a double (D) engagement system-were placed in the human mandibular molar region. Two types of abutments (hexagonal, conical) were connected to the implants. Different implant models (a single implant, two parallel implants, and mesial and tilted distal implants with 1-mm bone loss) were assumed. A static axial force and a 45-degree oblique force of 200 N were applied as the sum of vectors to the top of the prosthetic occlusal surface with a preload of 30 Ncm in the abutment screw. The von Mises stresses at the implant-abutment and abutment-screw interfaces were measured. Results In the single implant model, the S-conical abutment type exhibited broader stress distribution than the S-hexagonal abutment. In the double engagement system, the stress concentration was high in the lower contact area of the implant-abutment engagement. In the tilted implant model, the stress concentration point was different from that in the parallel implant model because of the difference in the bone level. Conclusion The double engagement system demonstrated a high stress concentration at the lower contact area of the implant-abutment interface. To decrease the stress concentration, the type of engagement features of the implant-abutment connection should be carefully considered.

The relationship between surface roughness and the optical characteristics of zirconia prostheses may be affected by the type of shaded block.The purpose of this in vitro study was to investigate changes in surface roughness and brightness of monolithic zirconia blocks of different shades after polishing.The surface roughness averages of 3 different kinds of shaded zirconia blocks (Zenostarof T0 [T0], Zenostar sun [Ts], and Zenostar sun chroma [Tsc]) were compared after surface polishing. Fifteen specimens of differing thicknesses were produced per block. (1 mm and 3 mm). Surface morphology and compositions were analyzed by using filed emission scanning electron microscopy (FE-SEM) and energy dispersive spectrometry. A 1-way ANOVA and the post hoc Scheffé test were performed (α=.05). The correlations between surface roughness and brightness were determined using the Pearson correlation analysis (α=.01).After phased polishing, Ts had the highest average roughness, followed by T0 and then Tsc. A statistically significant difference in roughness was observed between Ts and Tsc (P.05). Ts exhibited multiple distinct layers in the FE-SEM image. Carbon was detected in the Ts specimens only. Brightness was highest in T0, followed by Ts and then Tsc. A positive correlation was observed between brightness and surface roughness for all specimens (P.01). This correlation was stronger in the thicker specimens.The results of this study suggest that polishing affects monolithic zirconia differently depending on shade. The polishing of monolithic zirconia reduces both surface roughness and brightness. The optical properties of monolithic zirconia vary by thickness and can be opaque or translucent.

A model with simulated flabby tissue was fabricated by modifying the standard maxillary edentulous acrylic resin cast to evaluate the effect of maxillary impression tray design on the displacement of flabby tissue. Seven groups of trays were fabricated using different combinations of relief spaces and escape holes. After impression taking, test and control casts were scanned and three-dimensional digital models were superimposed. Negative deviations were recorded at the point of the alveolar crest, the posterior part of the flabby tissue, and the middle of the palate, while positive deviations were recorded at the point of the anterior part of flabby tissue. The amount and characteristics of tissue displacement differed with tray design and the relief method used.

This study investigated stress distribution in four different implant-abutment interface conditions in the internal tapered connection implant system. Four different implant diameters (3.5 mm, 4.0 mm, 4.5 mm, and 5.0 mm) and two abutment types (hexagonal and conical) were simulated. Four unique implant-abutment interface conditions were assumed based on wall thickness, mating surface length, distance to the vertical stop, and abutment shape. Axial and oblique loading was applied during abutment screw preload, and the Von Mises stresses were measured at the implant-abutment and abutment-screw interfaces. The implant-abutment interface stress decreased as the wall thickness increased. As the mating surface increased, the stress distribution trended downward, and when the distance to the implant vertical stop was 0 μm, the Von Mises stress was extremely high at the vertical stop. Despite their different shapes, the abutments showed similar stress distributions. However, the maximum Von Mises stress was higher in the conical connection than in the hexagonal connection, particularly at the contralateral side to loading. To decrease the stress distribution at the implant-abutment interface, the implant wall thickness, mating surface contact length, distance to the vertical stop, and abutment shape should be carefully considered.

Surface characteristics and cellular response to titanium surfaces that had been implanted with calcium and magnesium ions using plasma immersion ion implantation and deposition (PIIID) were evaluated. Three different titanium surfaces were analyzed: a resorbable blast media (RBM) surface (blasted with hydroxyapatite grit), a calcium ion-implanted surface, and a magnesium ion-implanted surface. The surface characteristics were investigated by scanning electron microscopy (SEM), surface roughness testing, X-ray diffraction (XRD), and Auger electron spectroscopy (AES). Human bone marrow derived mesenchymal stem cells were cultured on the 3 different surfaces. Initial cell attachment was evaluated by SEM, and cell proliferation was determined using MTT assay. Real-time polymerase chain reaction (PCR) was used to quantify osteoblastic gene expression (i.e., genes encoding RUNX2, type I collagen, alkaline phosphatase, and osteocalcin). Surface analysis did not reveal any changes in surface topography after ion implantation. AES revealed that magnesium ions were present in deeper layers than calcium ions. The calcium ion- and magnesium ion-implanted surfaces showed greater initial cell attachment. Investigation of cell proliferation revealed no significant difference among the groups. After 6 days of cultivation, the expression of RUNX2 was higher in the magnesium ion-implanted surface and the expression of osteocalcin was lower in the calcium ion-implanted surface. In conclusion, ion implantation using the PIIID technique changed the surface chemistry without changing the topography. Calcium ion- and magnesium ion-implanted surfaces showed greater initial cellular attachment.

PURPOSE The aim of this study was to investigate the stress distribution of 2-short implants (2SIs) installed in a severely atrophic maxillary molar site. MATERIALS AND METHODS Three different diameters of internal connection implants were modeled: narrow platform (NP), regular platform (RP), and wide platform (WP). The maxillary first molars were restored with one implant or two short implants. Three 2SI models (NP-oblique, NP-vertical, and NP-horizontal) and four single implant models (RP and WP in a centered or cantilevered position) were used. Axial and oblique loadings were applied on the occlusal surface of the crown. The von Mises stress values were measured at the bone-implant, peri-implant bone, and implant/abutment complex. RESULTS The highest stress distribution at the bone-implant interface and the peri-implant bone was noticed in the RP group, and the lowest stress distribution was observed in the 2SI groups. Cantilevered position showed unfavorable stress distribution with axial loading. 2SI types did not affect the stress distribution in oblique loading. The number and installation positions of the implant, rather than the bone level, influenced the stress distribution of 2SIs. The implant/abutment complex of WP presented the highest stress concentration while that of 2SIs showed the lowest stress concentration. CONCLUSION 2SIs may be useful for achieving stable stress distribution on the surrounding bone and implant-abutment complex in the atrophic posterior maxilla.

PURPOSE The effect of silica-based glass-ceramic liners on the tensile bond strength between zirconia and resin-based luting agent was evaluated and compared with the effect of 10-methacryloyloxydecyl dihydrogen phosphate (MDP)-containing primers. MATERIALS AND METHODS Titanium abutments and zirconia crowns (n = 60) were fabricated, and the adhesive surfaces of the specimens were treated by airborne-particle abrasion. The specimens were divided into 5 groups based on surface treatment: a control group, 2 primer groups (MP: Monobond Plus; ZP: Z Prime Plus), and 2 liner groups (PL: P-containing Liner; PFL: P-free Liner). All specimens were cemented with self-adhesive resin-based luting agent. After 24-hour water storage and thermocycling (5,000 cycles, 5℃/55℃), the tensile bond strength was measured using a universal testing machine. Failure mode analysis and elemental analysis on the bonding interface were performed. The data were analyzed using Kruskal-Wallis test, Dunn's post hoc test, and Fisher's exact test. RESULTS The liner groups and primer groups showed significantly higher tensile bond strengths than that of the control group (P

임상치관이 짧아 보철 수복이 어려운 경우 임상치관연장술이 효과적인 치료법이 될 수 있다. 임상치관 연장을 위한 술식에는 수술적 치관연장술, 교정적 정출술, 외과적 정출술이 있는데, 임상상황을 고려하여 최선의 선택을 해야 한다. 수술적 방법과 교정적 방법을 선택할 때, 적절한 고려사항과 주의점에 대해 여러 증례...

Statement of problem Although a well-polished monolithic zirconia surface is essential, insufficient comparative studies on the constituents and efficacy of polishing systems have been conducted. Purpose The purpose of this in vitro study was to analyze the abrasive constituents and compare the polishing effectiveness of 6 zirconia polishing systems, including their potential influence on the phase transformation of monolithic zirconia. Material and methods The compositions of 6 zirconia polishing systems were analyzed using energy dispersive spectroscopy (EDS). Sintered and high-speed ground monolithic zirconia specimens were used as control groups (n=14 specimens per group). Test groups (n=168) were pretreated identically to the control group and arbitrarily divided into 12 groups to examine 6 polishing systems for 2 polishing periods (60 or 120 seconds). The surfaces were characterized by a surface profiler and various analytic techniques, including x-ray diffraction (XRD) analysis. The data were analyzed using 2-way ANOVA and multiple comparisons and the Bonferroni method (α=.05). Results The abrasives were primarily composed of C, O, and Si. Diamond was identified as the main abrasive and SiC as the supplementary abrasive in the polishing systems. No significant differences were observed for the 60- or 120-second polishing times ( P> .05). Four products had significantly lower surface roughness values than the other 2 ( P .001). The occlusal-adjustment-simulating pretreatment and polishing processes did not cause phase transformations in the zirconia specimens. Conclusions The monolithic zirconia polishing systems contained diamond and SiC abrasives. All zirconia polishing systems showed clinically acceptable results, and 4 systems exhibited lower surface roughness. Phase transformation did not occur during polishing procedure.

과도한 수직피개를 가진 과개교합 환자에서 안정적인 유지접촉이 없는 경우 연조직 외상, 치질 파괴, 대합치 정출의 문제가 일어날 수 있고 이는 결과적으로 교합평면의 붕괴와 기능적, 심미적 문제로 이어진다. 치아의 상실과 마모가 발생된 환자에 대한 치료계획 수립 시 올바른 교합수직고경 설정을 통해 환자의 안정적...

PURPOSE The aim of this study was to investigate the effect of reinforcing materials on the fracture resistances of glass fiber mesh- and Cr–Co metal mesh-reinforced maxillary complete dentures under fatigue loading. MATERIALS AND METHODS Glass fiber mesh- and Cr–Co mesh-reinforced maxillary complete dentures were fabricated using silicone molds and acrylic resin. A control group was prepared with no reinforcement (n = 15 per group). After fatigue loading was applied using a chewing simulator, fracture resistance was measured by a universal testing machine. The fracture patterns were analyzed and the fractured surfaces were observed by scanning electron microscopy. RESULTS After cyclic loading, none of the dentures showed cracks or fractures. During fracture resistance testing, all unreinforced dentures experienced complete fracture. The mesh-reinforced dentures primarily showed posterior framework fracture. Deformation of the all-metal framework caused the metal mesh-reinforced denture to exhibit the highest fracture resistance, followed by the glass fiber mesh-reinforced denture (P

In restorative treatment using fixed dental prostheses, dentists should select appropriate restoration material among various types of dental materials. The strength, marginal fit, esthetics, wear resistance, biocompatibility, and cost are important factors in the choice of restoration materials. The present case showed a surface stain on a monolithic zirconia restoration that was due to wear between the monolithic zirconia restoration and the base metal alloy restoration. This phenomenon was confirmed by surface roughness measurement and electron probe micro-analysis.

Oligodontia is defined as a congenital tooth agenesis with the absence of six or more permanent teeth. This clinical report describes a patient with non-syndromic partial oligodontia, with retained deciduous teeth and the absence of 16 permanent teeth. Anterior esthetic problems were caused by interarch tooth size discrepancy, interdental space, aberrant tooth dimensions, and the absence of centric contacts of the anterior teeth. Prosthetic restoration after orthodontic and implant treatment was performed with a multi-disciplinary team approach. Favorable functional and esthetic results were obtained using a definitive prosthesis.