Interfacial Fracture Toughness of Adhesive Resin Cement-Lithium-Disilicate/Resin-Composite Blocks.

PURPOSE: Resin composite blocks (RCB) are advocated as alternative to ceramic blocks (CB). Prior to use, adherence to these materials should characterized. This study aimed to test the null hypothesis (H0 ) that material and surface treatment combinations do not influence interfacial fracture toughness (KIC ) of a self-cured adhesive resin cement [RelyX Ultimate (RXU)] to RCB or CB, under nonaged and aged conditions. MATERIALS AND METHODS: Two RCB, Lava Ultimate (LU) and Enamic (EN), and one CB, IPS e.max Press (EMP) were used. Half-size [(6 × 6 × 6 × 6 mm)] specimens were prepared for EMP (n = 30), EN (n = 30), and LU (n = 60). RCB specimens were prepared by wet cutting/grinding, while CB specimens were pressed. Surfaces of EMP and EN were preconditioned with hydrofluoric acid (5%); surfaces of LU were sandblasted with either 27 µm alumina (LUS) or 30 µm silica-modified alumina Rocatec soft (LUR). All specimens were bonded with Scotchbond Universal adhesive and RXU. Additionally, twenty (4 × 4 × 4 × 8 mm) RXU specimens were prepared. All specimens were stored in water at 37°C and tested after 1 and 60 days. Interfacial KIC was determined with the notchless triangular prism specimen KIC test. Results were analyzed with two-way ANOVA and Scheffé multiple means comparisons (α = 0.05). Preconditioned and selected fractured surfaces were characterized with scanning electron microscopy. RESULTS: At 24 hours, LUS-RXU and LUR-RXU had significantly higher interfacial KIC than EN-RXU and EMP-RXU and were not different from KIC of RXU. Aging lead to a significant decrease in KIC of RXU and interfacial KIC of LUS-RXU, LUR-RXU, and EMP-RXU; interfacial KIC of EN-RXU was not affected. Based on the results, H0 was rejected. CONCLUSION: Under the conditions of this study, at 24 hours, interfacial KIC of LUS-RXU and LUR-RXU was superior to EMP-RXU and EN-RXU. Aging in water at 37°C did not affect interfacial KIC of EN-RXU but adversely affected KIC of RXU and the other interfacial KIC . CLINICAL IMPLICATIONS: The results suggest that RXU and its adherence to LU and EMP deteriorates upon exposure to water at 37°C. In making clinical decisions related to material selection, practitioners should consider in vitro results.

Effects of fabrication and shading technique on the color and translucency of new-generation translucent zirconia after coffee thermocycling.

STATEMENT OF PROBLEM: The color stability and translucency of preshaded and externally shaded monolithic and veneered new generation translucent zirconia are not well known. PURPOSE: The purpose of this in vitro study was to investigate the effect of fabrication (veneered or monolithic) and shading (preshaded or externally shaded) techniques on the color and relative translucency of translucent zirconia after coffee thermocycling. MATERIAL AND METHODS: Specimens of different thicknesses (0.5 mm for veneered and 1.5 mm for monolithic) were sectioned from preshaded and externally shaded translucent zirconia. Externally shaded specimens were colored by using the dipping technique. Externally shaded (Ext Mono) and preshaded (Pre Mono) monolithic zirconia specimens were sintered and glazed. Externally shaded (Ext Vene) and preshaded (Pre Vene) 0.5-mm-thick specimens were sintered, veneered with feldspathic porcelain (1 mm), and glazed. The color coordinates of specimens were measured with a spectroradiometer before and after 10 000 thermocycles in coffee solution. Color differences were calculated using CIEDE2000, and relative translucency parameter (RTP) values were calculated using the RTPCIEDE2000 formula. Analysis of variance (ANOVA) was used to analyze the CIEDE2000 color differences and RTP values (α=.05). RESULTS: Shading technique had a significant effect on the color difference values (P=.018). For the translucency data, the 3-way ANOVA revealed a significant interaction between the fabrication technique and shading technique (P=.002). Each pair of material subgroups within each combination of fabrication technique and shading technique was found to have a significantly different RTP, except between Ext Vene and Pre Vene (P=.115). CONCLUSIONS: Externally shaded translucent zirconia had a greater color change in coffee than the preshaded translucent zirconia, either in monolithic or veneered form. Fabrication technique significantly affected the RTP, and the monolithic zirconia was more translucent than the veneered zirconia.

Effect of shading technique and thickness on color stability and translucency of new generation translucent zirconia.

OBJECTIVE: To evaluate the effect of shading technique and thickness on the color stability and translucency of translucent zirconia after coffee thermocycling. METHODS: Specimens in different thicknesses (1; 1.5; 2 mm) (n = 4 for each thickness) were sectioned from translucent preshaded zirconia (Pre) and externally shaded zirconia (Ext). After sintering, specimens were glazed and subjected to 10,000 thermocycling in coffee solution. The color coordinates of specimens were measured with a spectroradiometer before and after coffee thermocyling. Color differences and relative translucency parameter (RTP) values were calculated with CIEDE2000 color difference and TPCIEDE2000 formulas. ANOVA was used to analyze the CIEDE2000 color difference and RTP values (α = 0.05). RESULTS: According to 2-way ANOVA, no significant effect of shading technique and thickness on the color difference values was found (P > .05). According to 3-way ANOVA, a significant interaction between the shading technique and thickness (P < .0001) was found for RTP. The RTP parameter decreased with the increase in the thickness. Ext specimens presented significantly higher RTP than Pre specimens (P < .0001), except for between Ext 1 mm and Pre 1 mm (P = .179). CONCLUSIONS: Neither shading technique nor tested thicknesses affected the color of translucent zirconia. Shading technique and thickness affected the RTP of translucent zirconia. The RTP was inversely affected with the thickness of the material. Externally shaded zirconia presented higher RTP than preshaded zirconia for specimens thicker than 1 mm. CLINICAL SIGNIFICANCE: Discoloration with coffee was insignificant for the tested translucent zirconia in tested thicknesses (1, 1.5, 2 mm). When a translucent restoration is intended, thinner externally shaded translucent zirconia restorations should be preferred instead of preshaded translucent zirconia.

Reabilitação do guia canino complementar ao tratamento harmônico e estético com prótese parcial fixa livre de metal / Rehabilitation of the canine guide complementary to the harmonic and aesthetic treatment with fixed partial denture of metal

Introdução: A reabilitação estética de dentes anteriores com próteses cerâmicas livres de metal proporciona excelência estética principalmente pela ausência da margem metálica. Pacientes que apresentam oclusão adequada e ausência de hábitos parafuncionais possuem menor chances de falhas catastróficas em movimentos excêntricos e bordejantes durante as excursões mandibulares. Objetivo: evidenciar, por meio de relato de um caso clínico, o reestabelecimento da estética e função de dentes anteriores, utilizando restaurações cerâmicas livres de metal. Conclusões: A utilização de cerâmicas livres de metal permitiu uma estética natural e funcional com ótimas propriedades ópticas, integrando as restaurações ao sorriso do paciente.(AU)

Introduction: The aesthetic rehabilitation of anterior teeth with metal-free ceramic prosthesis provides aesthetic excellence mainly due to the absence of metal margin. Patients with adequate occlusion and absence of parafunctional habits have a lower chance of catastrophic failure in eccentric movements and contours during mandibular excursions. Aim: to report, through a clinical case report, reestablishment of aesthetics and function of anterior teeth, using metal free ceramic restorations. Conclusions: The use of free metal ceramics allowed a natural and functional aesthetic with excellent optical properties, integrating the restorations to the patient's smile.(AU)

Functionalized pink Al2O3:Mn pigments applied in prosthetic dentistry.

STATEMENT OF PROBLEM: The color of dental poly(methyl methacrylate) (PMMA) is conventionally rendered by organic and inorganic pigments, which are usually not bonded to the polymer network. Functionalized ceramic pigments can be used to color PMMA, allowing improved chemical interaction with the resin matrix. PURPOSE: The purpose of this in vitro study was to synthesize, functionalize, and characterize pink manganese-doped alumina ceramic pigments. The hypothesis tested was that functionalized ceramic pigments would render pink coloration to a translucent PMMA without jeopardizing its mechanical properties. MATERIAL AND METHODS: Pink alumina powders doped with 1 or 2 mol% of manganese (Al2O3:Mn) were prepared by means of a polymeric precursor method. Pigment (Pig.) particles were functionalized with a silica coating method followed by silanation before preparation of PMMA-based composite resins (5 wt% pigment). The color of composite resins (Pig.1% and Pig.2%) and PMMA controls (Pink and translucent [Trans]) was evaluated (CIELab color coordinates), and their mechanical properties were tested (3-point bending). RESULTS: The microstructure of the pigment particles showed approximately 55-nm nanocrystals of manganese-doped α-alumina clustered into irregular porous particles up to 60 µm. The composite resins and pink PMMA showed similar color parameters (CIE a* pink=20.1, Pig.1%=14.6, Pig.2%=16.0, Trans=0.19, P<.001; CIE b* Pink=17.0, Pig.1%=18.6, Pig.2%=19.0, Trans=2.52, P<.001). No statistical differences were observed in mechanical properties among groups (σf pink=98.4, Pig.1%=98.1, Pig.2%=98.8, trans=89.1, P=.136). CONCLUSIONS: The addition of the functionalized pink ceramic pigments to a translucent PMMA yielded similar coloration to that of the regular pink PMMA used in dentistry and did not jeopardize its mechanical properties.

Ceramic dental biomaterials and CAD/CAM technology: state of the art.

PURPOSE: Ceramics are widely used as indirect restorative materials in dentistry because of their high biocompatibility and pleasing aesthetics. The objective is to review the state of the arts of CAD/CAM all-ceramic biomaterials. STUDY SELECTION: CAD/CAM all-ceramic biomaterials are highlighted and a subsequent literature search was conducted for the relevant subjects using PubMed followed by manual search. RESULTS: Developments in CAD/CAM technology have catalyzed researches in all-ceramic biomaterials and their applications. Feldspathic glass ceramic and glass infiltrated ceramic can be fabricated by traditional laboratory methods or CAD/CAM. The advent of polycrystalline ceramics is a direct result of CAD/CAM technology without which the fabrication would not have been possible. CONCLUSIONS: The clinical uses of these ceramics have met with variable clinical success. Multiple options are now available to the clinicians for the fabrication of aesthetic all ceramic restorations.

Effect of thickness of zirconia-ceramic crown frameworks on strength and fracture pattern.

The aim of the present study was to evaluate the fracture load and fracture mode of thin Ceria-stabilized tetragonal zirconia polycrystals/Al(2)O(3 )nanocomposites (Ce-TZP/A) and Yttria-stabilized tetragonal zirconia polycrystals (Y-TZP) crown frameworks. Artificial maxillary second premolars were prepared for metal-ceramic crown and all-ceramic crown restorations and Co-Cr tooth analogs were duplicated. 10 standard (0.5 mm overall thickness) zirconia-ceramic crown frameworks (Y-TZPs) for all-ceramic crown preparation and 10 modified (a 0.3-mm-thick framework increased in thickness by adding a 1.0-mm-thick palatal margin with a height of 2.0 mm) zirconia-ceramic crown frameworks (Y-TZPm, Ce-TZP/Am) for metal-ceramic crown preparation were fabricated. The frameworks were cemented to the Co-Cr tooth analog and loaded vertically until fracture. The fracture load of Y-TZPs (180.0 N) and Ce-TZP/Am (183.7 N) were significantly higher than that of Y-TZPm (133.7 N). There was a significant difference in fracture mode between Y-TZPm and Ce-TZP/Am. Within the limitation of this study, Ce-TZP/Am provide sufficient strength for clinical application.

Three-dimensional fit of CAD/CAM-made zirconia copings.

OBJECTIVES: CAD/CAM-technologies aim for a standardized, accurate production of dental restorations out of high strength materials (zirconia). The three-dimensional internal fit of CAD/CAM-manufactured zirconia copings was evaluated in vitro to verify the realizability of this aim. METHODS: The analysis was based on ceramic master dies of prepared teeth and corresponding virtual CAD surfaces. Five copings per die were manufactured with two different CAD/CAM-technologies: milling and grinding. The internal fit was determined by a three-dimensional replica technique by optical digitization and computer-assisted analysis. RESULTS: Mean internal gaps were 134/84µm (SD 78/28) for molar and 93/69µm (SD 56/35) for premolar copings (milling/grinding) using a digitizable silicone for the replicas representing the cement space; they were statistically significant regarding tooth and CAD/CAM-system (p<0.001). SIGNIFICANCE: All zirconia copings showed an internal accuracy of fit where the gap widths ranged within the current clinical recommendations. However, there still is room for improvement and further standardization of CAD/CAM-technologies.

Five-year clinical evaluation of In-Ceram crowns fabricated using GN-I (CAD/CAM) system.

This study prospectively evaluated the clinical performance of computer-assisted design and computer-assisted manufacturing (CAD/CAM)-generated In-Ceram Alumina core crowns in Japanese patients for up to 5 years. A total of 101 In-Ceram crowns with aluminium copings fabricated using the GN-I system were placed in Japanese patients. The crowns were evaluated using a California Dental Association (CDA) quality assessment system at baseline and at all follow-up examinations. Gingival condition was assessed using plaque and bleeding scores. The survival of anterior and posterior crowns was analysed according to the Kaplan-Meier method. The scores of gingival condition were compared between restored crowns and contralateral teeth using a t-test. During the observation period, six crowns were lost to follow-up. Five crowns were fractured from the copings and removed, and four crowns were removed for other reasons. Chipping within the porcelain was detected in three crowns, which were then polished. The cumulative survival rates after 60 months were 96·9% for anterior crowns and 87·7% for posterior ones, and there were no significant differences between anterior and posterior crowns. According to the CDA criteria, most of the crowns were rated as satisfactory during the observation period. There were significant differences in soft tissue conditions between In-Ceram crowns and control teeth at 2- and 5-year examinations. Despite the five fractures from copings, In-Ceram Alumina crowns with copings fabricated using the CAD/CAM (GN-I system) for replacing both anterior and posterior teeth showed predictable results during a 5-year observation period.

In vitro evaluation of marginal adaptation in five ceramic restoration fabricating techniques.

OBJECTIVE: To compare in vitro the marginal adaptation of crowns manufactured using ceramic restoration fabricating techniques. METHOD AND MATERIALS: Fifty standardized master steel dies simulating molars were produced and divided into five groups, each containing 10 specimens. Test specimens were fabricated with CAD/CAM, heat-press, glass-infiltration, and conventional lost-wax techniques according to manufacturer instructions. Marginal adaptation of the test specimens was measured vertically before and after cementation using SEM. Data were statistically analyzed by one-way ANOVA with Tukey HSD tests (a = .05). RESULTS: Marginal adaptation of ceramic crowns was affected by fabrication technique and cementation process (P < .001). The lowest marginal opening values were obtained with Cerec-3 crowns before and after cementation (P < .001). The highest marginal discrepancy values were obtained with PFM crowns before and after cementation. CONCLUSION: Marginal adaptation values obtained in the compared systems were within clinically acceptable limits. Cementation causes a significant increase in the vertical marginal discrepancies of the test specimens.

Clinical evaluation of Procera AllCeram crowns in Japanese patients: results after 5 years.

Procera AllCeram crowns were prospectively evaluated clinically in both anterior and posterior regions in Japanese. One-hundred and one crowns were fabricated for 57 patients at the Tsurumi University Dental Hospital from August 2001 to October 2002 and evaluated according to the California Dental Association (CDA) quality evaluation system at baseline and annually at all follow-up examinations for 5 years. The plaque index (PI) and gingival index (GI) were recorded, and chipping and fracture were checked at the same time as well. A total of 75 Procera AllCeram crowns were evaluated, and the cumulative survival rate was 90.2% over the 5-year clinical trial. Six crowns experienced fractures within the veneering porcelain and from aluminium oxide coping, all of which occurred on the premolar and molar regions, and they had to be removed. Small chipping was observed on three crowns. According to the CDA criteria, 98% of Procera AllCeram crowns were rated as satisfactory, and PI and GI were comparable to those of control teeth during the observation period.

Micro-CT evaluation of the marginal fit of different In-Ceram alumina copings.

The aim of the study was to evaluate the marginal fit of different In-Ceram alumina ceramic cores manufactured by four different techniques. Four groups of four In-Ceram alumina core specimens (Vita), each 0.6 mm in thickness, were fabricated from a master die using four different techniques: Group SL, the slip-cast technique (In-Ceram system); Group CL, the copy-milling technique (Celay system); Group CR, a CAD/CAM system (Cerec inLab system) and Group WO, the electro-deposition dipping technique (Wol-Ceram). After the core specimens were fitted on the master die, they were scanned with the use of a microtomography device (1072 micro-CT, Sky- Scan). Datasets were processed by software (TView v1.1, SkyScan) and 10 vertical sections from each core were generated. On these microtomographic cross-sections the marginal gap (MG) and the absolute marginal discrepancy (MD) were measured in microscale (microm). The slip-cast and the electro-deposition dipping techniques presented the best results of MG with 22 microm and 35 microm, respectively (alpha<5%). The CAD/CAM system presented an MG of 55 microm. In addition, the slip-cast and the electro-deposition dipping techniques presented the best results of MD with 50 microm and 60 microm, respectively (alpha<5%). The slip-cast technique and the Wol-Ceram system presented the best marginal fit, followed by Cerec inLab, which presented clinically acceptable results. Microtomography analysis seemed to be a reliable method of evaluating the marginal fit of dental restorations.

Ceramics in implant dentistry (Working Group 1).

INTRODUCTION: The remit of this working group was to update the existing knowledge base in ceramics in implant dentistry. The reviews from working group 1 formed the basis for this update. Moreover, clinical applications as well as suggestions for further research have been formulated. MATERIALS AND METHODS: The papers in the working group critically reviewed the literature on the topic. Manuscripts were produced on: 1. The performance of ceramic and metal implant abutments supporting fixed implant reconstructions. 2. The viability of ceramic implants as alternatives to titanium implants. 3. The survival and complications of CAD-CAM reconstructions as compared with FDPs which have been fabricated using conventional techniques. RESULTS: The results and conclusions of the review process are presented in the following papers, together with the group consensus statements, clinical implications and directions for future research: Sailer I., Philipp A., Zembic A., Pjetursson B. E., Hämmerle C. H. F., Zwahlen M. A systematic review of the performance of ceramic and metal implant abutments supporting fixed implant reconstructions. Andreiotelli M., Wenz H. J., Kohal R.-J. Are ceramic implants a viable alternative to titanium implants? A systematic literature review. Harder S., Kern M. Survival and complications of CAD-CAM vs. conventionally fabricated reconstructions: a systematic review.

[Enforcing osseointegration of dental implantates spray-coated by bioceramics with the help of hyaluronic acid and hydroxyapatite gel in experimental conditions].

Influence of HAP-gel (2 g of 2% solution of hyaluronic acid mixed with 0,5 g of hydroxyapatite and 0,1 ml of colloidal silver) upon osseointegration in case of delayed introduction of titanium implantates in dog jaw. By scanning electron microscopy it was shown that solely use either of HAP-gel or of ceramic spraying increased direct contact area between bone and implantates in the 6 and 9 months time period. Combination of spray-coated ceramic with HAP-gel was effective in 3 months after implantation, when solely the HAP-gel or the ceramic spraying were little effective. In the following terms of experiment (6 and 9 months) significant differences between groups 3 and 4 (implantate with ceramic spraying but without HAP-gel in the alveolus and implantate with ceramic spraying and with HAP-gel in the alveolus) were not found. The area of implantate integration with jaw bone (cortical part of it was excluded) was equal to 80% and was maximal for the given conditions of the experiment.

Shading of ceramic crowns using digital tooth shade matching devices.

In the 1990s, there was great optimism due to the development of devices for measuring tooth shade. The frequently not so simple, visual determination of the shade of a tooth was to be done with the aid of a device which recognizes the shade and describes it accurately by reference to a color chart. However, the skepticism towards such devices was also great. It is known that the color effect frequently differs strongly when comparing a tooth from the shade guide with a metal ceramic crown, despite identical shade designation. Anyone who considers visual shade determination to be inadequate and places his hopes in digital shade matching devices will be disappointed. It is the shade-generating structures of the metal ceramic and frequently of the veneer layers that turn out to be too thin which, despite correct shade selection, cause a different color perception. Such problems have been reduced decisively with the development of fracture-proof hard porcelain caps (Vita In-Ceram) with optical characteristics similar to teeth. In addition, the Vita System 3D-Master tooth shade system developed in 1998 by Vita in cooperation with Dr. Hall from Australia, leads the practitioner to a better understanding of the primary tooth shade characteristics of "brightness (value)", "color intensity (chroma)" and "color (wave length of the visible light, hue)". These two innovations allow a more accurate estimate of the basic shade of a natural tooth (reference tooth) and the imitation in the laboratory of its natural, shade-generating structures. If digital shade measurement supplements the visual shade estimate, then a further improvement can be expected--especially in the recognition of the basic shade. Qualitative descriptions of subjective shade measurement of a natural tooth and of its imitation in the dental laboratory by ceramics can be found frequently in professional journals and publications. With digital tooth shade matching devices, which apart from the color code of the color chart also reproduce exact, colorimetric values, such work processes can be recorded quantitatively and objectively. Reports about this type of controlled shade determination and generation are found rarely in the literature, which is surprising in view of the large number of tooth shade matching devices and dental ceramic systems available. In the present paper, the influence of the individual ceramic layers on color perception is measured and described under standardized conditions. The creation of the basic shade as it results from the composition of the various ceramic layers is traced with a spectrophotometer. The Vita In-Ceram Alumina infiltration ceramic and the VitaVM7 veneer ceramic were selected as the ceramic system. MHT-SpectroShade and Vita Easyshade were used as shade matching devices.

Clinical marginal and internal gaps of In-Ceram crowns fabricated using the GN-I system.

The marginal and internal gaps of ceramic crowns with alumina copings fabricated using a computer-aided design, computer-aided manufacturing system, were evaluated in vivo using silicone materials. Black and white silicone materials were used to record the marginal and internal gaps of 82 In-Ceram crowns before final cementation. The silicone materials were sectioned bucco-lingually and mesio-distally and viewed under a microscope to measure the thickness of the white silicone layer. Sixteen reference points were measured on each specimen. The mean marginal gaps were compared among the anterior, premolar and molar teeth, and the mean gaps at the reference points within the groups were compared by analysis of variance and the Dunnett T3 test. The mean marginal gap was 66.8 mum. There were no differences in marginal gaps among the three groups. In all the groups, the marginal gaps were the smallest, whereas the occlusal gaps were the largest. The mean marginal gaps of the In-Ceram crowns with the alumina copings fabricated using the GN-I system were within the range of clinically acceptable values.

CAD/CAM systems, materials, and clinical guidelines for all-ceramic crowns and fixed partial dentures.

Advances in dental ceramic materials and the development of computer-aided design/computer-aided manufacturing (CAD/CAM) and milling technology have facilitated the development and application of superior dental ceramics. CAD/CAM allows the use of materials that cannot be used with conventional dental processing techniques. This article reviews the main techniques and new materials used in dentistry for CAD/CAM-generated crowns and fixed partial dentures. Also covered are the clinical guidelines for using these systems.

Management of complex implant aesthetics: ensuring restorative design continuity with a comprehensive outcome-based strategy.

Since implant therapy must be dictated by prosthetic requirements, a protocol for the comprehensive and continuous integration of the restorative blueprint through the entire treatment planning and clinical execution phases is mandatory. This article demonstrates a systematic approach where the establishment of a final restorative treatment objective is incorporated into the diagnosis and subsequently integrated through every phase of clinical execution. Design continuity is ensured, and multidisciplinary cohesiveness is enhanced by providing clearly defined treatment objectives to every member of the clinical team.

Fracture strength of copy-milled and conventional In-Ceram crowns.

The purpose of this study was to compare the fracture resistance of copy-milled and conventional In-Ceram crowns. Four groups of 10 uniform sized all-ceramic anterior crowns were fabricated for this test: (1) In-Ceram Spinell (2) In-Ceram Alumina (3) Celay In-Ceram Spinell, and (4) Celay In-Ceram Alumina crowns. All specimens were cemented on stainless steel master die with resin cement and stored in 37 degrees C water for one day prior to loading into a universal testing machine. Using a steel ball at a crosshead speed of 0.5 mm min-1, the crowns were loaded at 30 degrees C angle until catastrophic failure occurred. Mean fracture strength was analysed and compared. Under the conditions of this study and the materials used, the following conclusions were drawn: 1. The strength of Celay In-Ceram anterior crowns had a slightly higher fracture strength than conventional In-Ceram crowns. 2. In-Ceram Alumina crowns had a significantly higher fracture strength than In-Ceram Spinell crowns in both conventional and copy milling methods.