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PubMed2003

Effect of ceramic surface treatment on the shear bond strengths of two resin luting agents to all-ceramic materials.

The purpose of this study was to evaluate the bond strengths of some resin luting cements of two different all ceramic materials (In-Ceram, IPS-Empress). Composite cylinders 3.2 x 2 mm were prepared on the ceramic surfaces for a shear test. Four ceramic surface treatments were performed. (i). As received, (ii). grinding with diamond bur, (iii). sandblasting with 50 microm alumina grit and (iv). HF acid treatment and sandblasting with 50 microm alumina grit. Ceramic specimens were treated with one of the four methods and then cemented together with each of the two luting agents. The tested luting cements were Panavia F and Clearfil Se Bond (CSeB). The CSeB demonstrated the highest bond strength (59.95 MPa) regardless of the ceramic blocks. The average of load to fracture the In-Ceram blocks luted with Panavia F cement was 25.89 MPa. The mean shear bond strength of IPS Empress blocks luted with Panavia F cement was 10.31 MPa. Grinding the surface with a diamond bur for In-Ceram blocks luted with Panavia-F was 30.93 MPa and with CSeB was 77.04 MPa. For IPS-Empress blocks these values decreased to 12.39 MPa for Panavia-F and 30.84 MPa for CSeB. Acid etching of the surfaces with HF acid demonstrated a weak tendency to improve bond strength (In-Ceram-->Panavia-F= 14.59 MPa and CSeB=59.32 Mpa; IPS-Empress--> Panavia-F=5.85 MPa and CSeB= 23.33 MPa).

Ceramics↗
PubMed2004

Survival rate of mono-ceramic and ceramic-core CAD/CAM-generated anterior crowns over 2-5 years.

Anterior mono-ceramic (Mk II, n = 18) and ceramic core (In-Ceram Spinell, n = 18) crowns were CAD/CAM-fabricated using Vitablocs with the Cerec 2 CAD/CAM system and bonded in 24 patients. All crowns were rated using modified United States Public Health Services (USPHS) criteria at baseline and after a service time of 2-5 years. Survival of the crowns, regarding fracture, was analysed (Kaplan-Meier) after 44.7 +/- 10.3 months. Gingival health at crowns was assessed using plaque and bleeding scores. One core crown and one mono-ceramic crown had fractured after 42.5 months and 12 months, respectively, with survival rates of 91.7% for In-Ceram Spinell and 94.4% for Mk II; the difference was not statistically significant. Between baseline and follow-up examinations, non-significant shifts from A- to B-ratings occurred, particularly for marginal adaptation, for both crown types. Plaque and bleeding scores did not differ between the ceramic crown types but showed significantly less plaque and less bleeding at ceramic crowns than at control teeth at follow-up. The clinical performance of mono-ceramic crowns was judged to be similar to that of ceramic core crowns.

Adult↗
PubMed2001

Effects of ceramic component on cephalexin release from bioactive bone cement consisting of Bis-GMA/TEGDMA resin and bioactive glass ceramics.

The purpose of this study was to elucidate the effect of amount of ceramic cement powder on drug release from bioactive bone cement. The associated bone-bonding strength was also investigated. The bioactive bone cement under investigation consisted of bisphenol-alpha-glycidyl methacrylate (Bis-GMA), triethylene-glycol dimethacrylate (TEGDMA) resin and a combination of apatite- and wollastonite-containing glass-ceramic (A-W GC) powder. A-W GC powder (50%, 70% and 80% w/w) containing 5% cephalexin (CEX) powder hardened within 5 min after mixing with Bis-GMA/TEGDMA resin. The compressive strength of the cement with or without drug increased with increasing the amount of ceramic powder. The compressive strength of the 80% ceramic cement without the incorporation of cephalexin was 194 MPa. This compressive strength was about 3 times higher than that for polymethylmethacrylate cement. After the cement was implanted in the proximal metaphysis of the tibiae of male rabbits, the failure load for the cement was found to increase with increasing of the amount of ceramic powder. This finding suggested that the cement formed a bonding with bone. In vitro CEX release from bioactive bone cement pellets in a simulated body fluid at pH 7.25 and 37 degrees C continued for more than 2 weeks. Drug release profile followed the Higuchi equation initially, but not at later stages. The drug release rate increased with increasing amount of ceramic powder in the mixture. Since the pore volume of the cement increased with increasing of amount of ceramic powder, the drug diffused in the pores between the ceramics particle and polymer matrix. As hydroxyapatite precipitated on the cement surface, the drug release rate decreased, as observed at the later release stage. These results suggest that varying the amount of ceramic powder in the cement system could control the drug release rate from bioactive bone cement.

Absorbable Implants↗
PubMed1983

[Obliteration of the mastoid cavity with porous tricalcium phosphate ceramic. Results 12 and 18 months after ceramic implantation in the hypotympanon of the pig].

The paper reports on the obliteration of mastoid cavities with resorbable tricalcium phosphate ceramic. As a model, we chose the pneumatic air cell system of the pig's hypotympanon, which resembles the human mastoid. At the time of surgery, the specimens were 10-12 weeks old. In a first group the cells of the hypotympanon were totally removed and the operation cavity was obliterated with adjacent layers of porous tricalcium phosphate ceramic. In a second group of specimens the air cell system was partly removed, leaving the apical part of the hypotympanon intact; the operation cavity was obliterated again with porous tricalcium phosphate ceramic. After 12 and 18 months survival the hypotympanons were removed and prepared for histological investigations. Those ceramic plates, lying close to the bony shell were strongly resolved and replaced by new bone. Other ceramic plates, however, especially those in the center of the implant, showed few signs of resorption and bony remodelling. Inside the ceramic implant there was hardly connective tissue. The space between the still unsolved ceramic plates was filled up with new bony tissue. This bone was partly structured and adjoined directly to the ceramic. The ceramic was integrated into the new bony tissue without any sign of an inflammation.

Animals↗
PubMed2005

Microtensile bond strength of different components of core veneered all-ceramic restorations. Part II: Zirconia veneering ceramics.

OBJECTIVES: The purpose of this research was to investigate microtensile bond strength between one type of zirconia substrate and various commercial veneer ceramics. The effect of an optional liner material between the core and veneer was also evaluated where applicable. METHODS: Bilayered zirconia veneer discs were fabricated from five layering and two pressable veneer ceramics. Additionally, discs from each veneer ceramic were prepared. The discs were cut into microbars of 6 mm in length and 1mm in cross-section. The microtensile bond strength was tested in a universal testing machine. The fracture surfaces of the microbars were examined with scanning electron microscopy (SEM) and EDAX. RESULTS: The microtensile strength of Rondo Dentine and Lava Dentine veneer ceramics were significantly higher than the other tested veneer ceramics. Furthermore, the layered systems Rondo Dentine and Ceram Express were significantly stronger than the other tested core-veneer ceramics. The application of liner material dramatically affected the bond strength and failure mode, which was also material dependent. SEM analysis showed that two pressable veneers and one type of layering veneer ceramic failed entirely cohesively in veneer side while the remaining test groups had higher percentage of interfacial failure. SIGNIFICANCE: Selection of stronger veneer ceramics which have good bond strength with zirconia can reduce the chances of chipping and delamination under function. The liner material should only be used with some layering veneers but not in combination with pressable veneers as it will result in weakening of the microtensile bond strength.

Analysis of Variance↗
PubMed2005

Influence of ceramic thickness and polymerization mode of a resin luting agent on early bond strength and durability with a lithium disilicate-based ceramic system.

STATEMENT OF PROBLEM: Attenuation of polymerization light energy by translucent all-ceramic materials may result in insufficient polymerization of underlying resin luting agents and inadequate early bond strength and durability. There is little information regarding the selection of an appropriate polymerization mode for cementing translucent all-ceramic restorations. PURPOSE: The purpose of this study was to evaluate the influence of ceramic thickness and polymerization mode on the early bond strength and bond durability of a lithium disilicate-based ceramic system. MATERIAL AND METHODS: The occlusal surfaces of 120 extracted, intact, human third molars were sectioned to expose a flattened area of dentin. The surface was etched with 32% phosphoric acid, and a single-step adhesive (One-Step) was applied to the etched dentin surfaces. Ceramic specimens (Empress 2), 6 mm in diameter and 1 mm, 1.5 mm, or 2 mm thick (n=40 per group), were fabricated using fluoropolymer resin matrixes. Each specimen was ground flat. Following hydrofluoric acid etching and silane treatment, ceramic discs of each thickness were further divided into 2 groups (n=20 per group) and bonded to the dentin surfaces with a dual-polymerized resin luting agent (Illusion), either with a catalyst (dual polymerization) or without a catalyst (light polymerization). A shear bond test was performed after 10 minutes (n=10) or after 24 hours following 1000 thermal cycles between 5 degrees C and 55 degrees C and a dwell time of 30 seconds (n=10). Debonded dentin surfaces were examined with SEM. The data were analyzed with 3-way analysis of variance (ANOVA) (alpha=.05). RESULTS: The shear bond strengths ranged between 13.2 +/- 4.1 MPa and 15.9 +/- 2.0 MPa. Three-way ANOVA revealed that ceramic thickness, polymerization mode, storage time, or combinations of these parameters did not influence shear bond strength. The location of failure for all specimens was adhesive, between the dentin surface and bonding agent. CONCLUSION: Both light polymerization and dual polymerization provided similar early shear bond strengths for the lithium disilicate-based ceramic system (Empress 2). The bond strength was not dependent on the thickness of the ceramic material tested. Durability of the bond was similar for both of the polymerization modes.

Analysis of Variance↗
PubMed2001

Morphologic characteristics of periprosthetic tissues from hip prostheses with ceramic-ceramic couples: a comparative histologic investigation of 18 revision and 30 autopsy cases.

Pseudocapsules and interface membranes from 18 revision cases having hip prostheses with ceramic-ceramic couples and 30 autopsy specimens (6 with ceramic-ceramic couples, 7 with ceramic-polyethylene combinations and 17 with metal-polyethylene combinations) were histomorphologically analyzed, including a semiquantitative grading of the wear particles and histologic changes. Unlike the revision cases, which usually showed ceramic wear particles in the adjacent tissues, only half of the autopsy cases revealed ceramic wear. As compared to the ceramic-polyethylene and metal-polyethylene couples, the alumina on alumina combinations showed a thinner synovial layer with reduced villous transformation and smaller infiltrates of macrophages and necroses, which can be explained by the absence of polyethylene wear. Metal-polyethylene couplings produced more than twice as many polyethylene wear particles with correspondingly more marked foreign body reaction than the ceramic-polyethylene couplings.

Adult↗
PubMed1989

[Finite element stress analysis of ceramics crown on premolar. Relation between ceramics materials and abutment materials].

This investigation was carried out to evaluate the alteration of stress distribution on ceramics crowns by each combination of ceramics crown materials and abutment materials. Analyzing the stress distribution by the finite element methods, a two-dimensional model of jacket crown preparation was designed on lower first premolar, and restored it by ceramics crown. Under four loading conditions, the tensile stress distributions on the ceramics crown were analyzed to evaluate the relations between three kinds of ceramics crown, which were an aluminous porcelain jacket crown, a feldspathic porcelain jacket crown and an Olympus castable ceramics (O.C.C.) crown, and three kinds of abutment which were a natural tooth, a gold cast core and a composite resin core. And following results were obtained: 1. When the abutment was a natural tooth, the tensile stresses were apt to occur all over the ceramics crown and these magnitude were increased in porportion to the height of Young's modulus of the ceramics materials. 2. When the abutment was a gold cast core or a composite resin core, the tensile stresses were produced only at the loading side of the ceramics crown, and the magnitude of stress were little affected by the type of core materials.

Composite Resins↗
PubMed2005

All-ceramic fixed partial dentures. Studies on aluminum oxide- and zirconium dioxide-based ceramic systems.

BACKGROUND: The development of refined, tougher, and stronger ceramic core materials in recent years has led to the wider use of new, strong all-ceramic systems based on oxide ceramics. Results from in-vitro studies investigating the use of oxide ceramics in shorter all-ceramic fixed partial dentures (FPDs) have been positive, but clinical studies and additional in-vitro studies are needed to confirm the advisability of such procedures. AIMS: One aim of this thesis was to investigate whether alumina-based and zirconia-based material systems are adequate for use in shorter (< or = five-unit) FPDs and to evaluate the clinical results. Additional aims were to investigate how to achieve optimal fracture strength in an all-ceramic FPD by varying the try-in procedure, the cervical shape of the abutments, and the support of the FPD (abutment teeth or dental implants). The final aim was to compare the strength of a zirconia material system with that of an alumina equivalent with known long-term clinical performance. MATERIALS AND METHODS: Two clinical studies investigating one alumina-based and one zirconia-based material system were performed. Twenty posterior, three-unit FPDs (glass-infiltrated alumina) were followed for 5 years and 20 three-five-unit FPDs (HIP zirconia) for 2 years. Long-term follow-ups were made after 11 +/-1 (glass-infiltrated alumina) and 3 years (HIP zirconia). In three in-vitro studies, the following variables were investigated: (1a) the flexural strength of porcelain specimens depending on whether they were exposed to saliva before the glaze firing (n=20) or first after the glaze firing (n=20), (1b) the fracture strength of three-unit all-ceramic FPDs (glass-infiltrated alumina) supported by abutments prepared with cervical shoulder preparations (n=9) and abutments with cervical chamfer preparations (n=9), (2) the fracture strength of crowns (n=30) made of a zirconia material system (densely sintered zirconia) and of crowns (n=30) of an alumina material system (densely sintered alumina) that had undergone three different pre-treatment modalities (water storage only; water storage and cyclic pre-loading; water storage, cyclic pre-loading, and thermocycling), (3) the fracture strength of all-ceramic FPDs (densely sintered alumina) supported by simulated teeth (n=12) or by dental implants (n=12). RESULTS: The success rate of the clinical alumina study was 90% after 5 years. Six (+/-1) years later (after a total of 11 +/-1 years), the success/survival rate was 65%. In the second clinical study, the success rates of the 2- and 3-year follow-ups were 100%. In the three in-vitro studies, the following results were found: (1a) the mean flexural strength of the specimens in the group that was exposed to saliva first after glazing was significantly higher (P < 0.001) than that of the specimens in the group that was exposed to saliva before glazing, (1b) the FPDs luted on shoulder preparations resisted higher loads than the FPDs luted on chamfer preparations (P = 0.051), 2) total fractures were more frequent in the alumina than in the zirconia group (P < 0.001), 3) FPDs loaded on implants resisted higher loads (mean = 604 N, SD=184 N ) than FPDs loaded on abutment teeth (mean= 378 N, SD=152 N, P = 0.003). CONCLUSIONS: This thesis justifies the use of shorter alumina- (< or = three-unit) and zirconia-based (< or = five-unit) FPDs as the clinical results are acceptable. The clinical performance of alumina is, however, not as good as that of comparable high-gold alloy based porcelain-fused-to-metal FPDs concerning fracture resistance. Within the limitations of the in-vitro studies: Saliva exposure of porcelain before glaze firing should be avoided to optimize the strength of the porcelain. Shoulder preparations can be beneficial for the strength of all-ceramic FPDs compared to chamfer preparations, as can support by dental implants compared to abutment teeth. The fracture mode of alumina crowns (total fractures) differs from that of zirconia crowns (veneer fractures), suggesting that the zirconia core is stronger than the alumina core.

Aluminum Oxide↗
PubMed2006

Delayed fracture of a ceramic insert with modern ceramic total hip replacement.

We report a case of ceramic liner fracture in a 34-year-old man that occurred 1 year 9 months after total hip arthroplasty with a BiCONTACT (Aesculap, Tuttlingen, Germany) ceramic-on-ceramic prosthesis. The ceramic liner was found within the metal shell in 4 large pieces and multiple small fragments in the peripheral portions. Its condition indicated that the possible mechanism of late ceramic liner chip fracture was repeated episodes of impingement between the prosthetic neck and the edge of the ceramic liner. Squatting, kneeling, and sitting cross-legged caused impingement. These positions are more common in Asian populations than in Western populations. After the joint was thoroughly irrigated, a new modular ceramic liner and a 28-mm ceramic head were implanted.

Adult↗
PubMed2006

No increased migration in cups with ceramic-on-ceramic bearing: an RSA study.

UNLABELLED: Ceramic-on-ceramic hip replacements might stress the bone interface more than a metal-polyethylene because of material stiffness, microseparation, and sensitivity to impingement. To ascertain whether this potentially increased stress caused an increased cup migration we compared a ceramic-on-ceramic with a metal-on-polyethylene implant for cup migration. Sixty one patients (61 hips) undergoing THA for osteoarthritis were randomized to ceramic on ceramic (Ce/Ce) or cobalt-chromium on cross-linked polyethylene bearings (PE) in the same uncemented cup shell. Migration was followed with RSA. At 2 years we observed similar mean cup translations in the 3 directions (0.07-0.40 mm vs. 0.05-0.31 mm, Ce/Ce vs. PE), as well as similar rotations around the 3 axes (0.31-0.92 degrees vs. 0.57-1.40 degrees). WOMAC and SF-36 scores were also similar and no radiolucent lines or osteolysis found. The large migration seen in some cups in both implant groups will require close monitoring to ascertain the reasons. Mean proximal wear of the polyethylene liners measured 0.016 mm between 2 and 24 months. Our data suggest there is no increased cup migration in the ceramic-on-ceramic implant compared with the metal-on-polyethylene, and they seem an equally safe choice. However, the low wear measured with the more versatile and less expensive cross-linked polyethylene makes it a strong contender. LEVELS OF EVIDENCE: Therapeutic Level I. See the Guidelines for Authors for a complete description of levels of evidence.

Aged↗
PubMed1984

The use of ceramics for bone replacement. A comparative study of three different porous ceramics.

Ceramics have many properties which might make them suitable alternatives to bone grafts. This present study was done to find a suitable biodegradable porous ceramic for human bone replacement. Three different porous ceramics (calcium aluminate, calcium hydroxyapatite and tricalcium phosphate), with interlinked pores of two size ranges (150 to 210 micron), were implanted into the skulls of rats and rabbits for up to six months; the interaction with surrounding bone, which is virtually devoid of bone marrow, was then assessed. The ceramics caused no adverse biological response. Tissue ingrowth into pores throughout the implant was seen in all three types and in both pore sizes of ceramic, but the density of the penetrating tissue was far less for calcium aluminate than for calcium hydroxyapatite or tricalcium phosphate. For each type of ceramic, the soft-tissue ingrowth was more dense with the larger pore size, and with a longer period of implantation. Bone ingrowth was not usually seen within the pores of any ceramic. There were no differences in the histological findings between the rats and the rabbits. The results demonstrate that it is possible to produce ceramic materials with a porous structure which allows ingrowth of tissue and biological fluids.

Aluminum↗
PubMed1997

Ceramic-ceramic and metal-polyethylene total hip replacements: comparison of pseudomembranes after loosening.

We made a semiquantitative study of the comparative histology of pseudomembranes from 12 loose cemented ceramic-ceramic and 18 metal-polyethylene total hip replacements. We found no significant difference in cellular reaction between the two groups, but there was a major difference in the origin of the particulate debris. In the metal-polyethylene group, polyethylene of articular origin was predominant, while in the ceramic-ceramic group the cellular reaction appeared to be a response to zirconia ceramic particles used to opacify cement used for fixation. Isolation and characterisation of the debris showed that the zirconia particles formed the greatest proportion (76%) in ceramic-ceramic hips, while alumina debris of articular origin formed only 12%. Our study has indicated that aseptic loosening of ceramic cups is not due to a response to debris generated at the articular interface, but to mechanical factors which lead to fragmentation of the cement.

Bone Cements↗
PubMed2002

The effect of multicolored machinable ceramics on the esthetics of all-ceramic crowns.

STATEMENT OF PROBLEMS: Computer-aided design/computer-assisted machining systems offer the possibility of fabricating restorations from one machinable ceramic block. Whether multishaded blocks improve esthetic results and are a viable alternative to individually stained ceramics has not been fully determined. PURPOSE: The aim of this investigation was to examine the effect of multishaded blocks on the esthetic appearance of all-ceramic CEREC crowns and compare these crowns with single-shade and stained restorations. MATERIAL AND METHODS: Ten subjects were included in this study. For each subject, 6 different crowns were milled with the use of a CEREC machine. One crown was milled from each of the following machinable ceramic materials: CEREC Vitablocs Mark II in classic colors; Vitablocs Mark II in 3D-Master colors; Vitablocs Mark II in either classic or 3D-Master colors, with additional staining; Megadenta Bloxx multishaded; Mark II experimental multilayer; and an experimental multilayer leucite ceramic. Three independent examiners assessed the esthetic appearance of crowns fabricated to match each subject's anterior tooth shade. A scale of 1 to 6 was used to score the shade match and esthetic adaptation of each crown, with 1 representing excellent characteristics and 3.5 serving as the threshold for clinical acceptability. The examiners' scores were averaged, and the mean values were analyzed with the Wilcoxon signed rank test (P<or=.05). RESULTS: Only individually stained Mark II restorations achieved a mean score below the threshold of 3.5 for all 10 subjects. These restorations were significantly more esthetic (P<or=.05) than restorations fabricated from all other materials except the Mark II experimental multilayer ceramic. The second best results were obtained for crowns made from single-shaded Mark II 3D-Master blocks: 6 out of 10 restorations were scored below 3.5. Two of the layered materials (Mark II experimental and Bloxx) followed with 5 acceptable restorations out of 10. CONCLUSION: Within the limitations of this study, the results provide no evidence that multicolored machinable ceramics improve the esthetics of all-ceramic crowns.

Aluminum Silicates↗
PubMed1998

All-ceramic alternatives to conventional metal-ceramic restorations.

In the search for the ultimate esthetic restorative material, many new all-ceramic systems have been introduced to the market. One such system, In-Ceram, is primarily crystalline in nature, whereas all other forms of ceramics used in dentistry consist primarily of a glass matrix with a crystalline phase as a filler. In-Cream can be used to make all-ceramic crowns and fixed partial denture frameworks. Three forms of In-Ceram, based on alumina, spinal (a mixture of alumina and magnesia), or zirconia, make it possible to fabricate frameworks of various translucencies by using different processing techniques. This article discusses clinical indications and contraindications for the use of In-Ceram Alumina and In-Ceram Spinell all-ceramic restorations. Particular attention is given to cement considerations using several clinical examples.

Aluminum Oxide↗