Re-assessing the notion(s) of craft standardization through diversity statistics: A pilot study on Late Chalcolithic pottery from Arslantepe in Eastern Anatolia.

This paper proposes a new range of diversity indexes applicable to ceramic petrographic and geochemical data and potentially to any archaeological data of both metric and non-metric nature in order to assess the degree of craft standardization. The case study is the Late Chalcolithic pottery from Arslantepe in eastern Anatolia, ideal to test the standardization hypothesis, i.e. the assumed correspondence between craft standardization and increased rates of production, which in turn correlate with economic specialization. The results suggest that the procurement and processing of raw materials are more sensible indicators of standardization than vessel shape variability. Higher standardization is connected with the scale of production rather than with the use of the wheel or its rotational speed. The socio-economic centralization marks a process of labor division within the operational sequence and, more generally, a shift from communal to more segregated potting practices. As a result, the variability of both technical procedures and end products increases. In contrast univocal trends towards standardization can be found in coeval contexts from northern Mesopotamia, where the incipient urbanization served to create bonds between vessel makers, favoring the transmission of models and practices regardless of the centralized power.

Methodology and model-based DSS to managing the reallocation of inventory to orders in LHP situations. Application to the ceramics sector.

Lack of homogeneity in the product (LHP) is a problem when customers require homogeneous units of a single product. In such cases, the optimal allocation of inventory to orders becomes much more complex. Furthermore, in an MTS environment, an optimal initial allocation may become less than ideal over time, due to different circumstances. This problem occurs in the ceramics sector, where the final product varies in tone and calibre. This paper proposes a methodology for the reallocation of inventory to orders in LHP situation (MERIO-LHP) and a model-based decision-support system (DSS) to support the methodology, which enables an optimal reallocation of inventory to order lines to be carried out in real businesses environments in which LHP is inherent. The proposed methodology and model-based DSS were validated by applying it to a real case at a ceramics company. The analysis of the results indicates that considerable improvements can be obtained with regard to the quantity of orders fulfilled and sales turnover.

Clinical outcomes of ceramic femoral prosthesis in total knee arthroplasty: a systematic review.

PURPOSE: Ceramic bearings have been widely used in total hip arthroplasty (THA), which resulted in satisfactory clinical outcomes due to the excellent tribological characteristics of the implants. However, ceramic components are not commonly used in total knee arthroplasty (TKA) because of brittleness. This study aimed to gather and analyze information regarding the clinical outcomes (including survival without revision, causes of revision, functional outcome, and incidence of loosening) and reach a definitive conclusion about the use of ceramic femoral components in total knee arthroplasty. METHODS: MEDLINE, EMBASE, Cochrane, and ClinicalTrials.gov databases were searched for studies that reported the clinical and/or radiological outcomes with or without survival data of ceramic TKA implants and that included more than 10 patients with a minimum of 1 year follow-up. RESULTS: From an initial sample of 147, there were 14 studies that met the inclusion criteria. Overall, there was a notable enhancement of joint function after the procedure, with a satisfactory mid- and long-term survival of the ceramic components, which is comparable to that of the conventional alloy components reported previously. In addition, the revision rate was reported to be between 0% and 14.37% according to the included studies. However, revision due to aseptic loosening, wear, and component fracture appeared to be rare, demonstrating the safety of in vivo use of ceramic bearings in the TKA procedure. CONCLUSIONS: Ceramic TKA implants show similar post-operative clinical results and survival rate compared to their conventional metallic counterparts. Our results confirmed the safety of in vivo use of ceramic bearings in TKA, with rare implant breakage and aseptic loosening. Considering the excellent characteristics of the tribology of ceramics, the clinical use of ceramic prostheses in TKA could be promising.

Influência do retratamento na formação de microtrincas dentinárias em molares inferiores obturados com o cimento biocerâmico total fill: análise por micro-ct / Influence of retreatment on the formation of dentinal microcracks in lower molars filled with total bioceramic cement fill: micro-ct analysis

Objetivo Este estudo teve como objetivo avaliar a incidência de microtrincas dentinárias após a remoção do material obturador utilizando o cimento biocerâmico TotalFill BC através de análises de microtomografia computadorizada (micro-CT). Metodologia Vinte raízes mesiais de molares mandibulares foram obturadas com guta percha e cimento Total Fill BC e em seguida o material obturador foi removido. As amostras foram escaneadas por micro-CT antes do preparo químico-mecânico, após a obturação e posteriormente a remoção do material obturador. As imagens transversais das raízes mesiais obtidas após a obturação foram analisadas e comparadas com as imagens após a remoção do material obturador, utilizando o programa Image J. Resultados Dos 24.444 cortes transversais analisados, 5,67% apresentaram algum defeito de dentina, sendo que nas imagens iniciais foram encontradas 0,51%, nas imagens pós obturação 2,58%, e nas imagens obtidas após a desobstrução 2,58%. Nas análises comparando as imagens iniciais e pós-obturação foram observados 1,65% dos cortes com novas microtrincas. Todos os defeitos dentinários identificados na análise das imagens obtidas após a remoção do material obturador já estavam presentes nas imagens correspondentes obtidas após a obturação. Desta forma, nenhuma nova microfissura foi observada após remoção do material obturador. Conclusão O estudo não visualizou a produção de novas microtrincas dentinárias durante a fase de desobstrução do retratamento endodôntico. (AU)

Aim The present study aimed to evaluate the frequency of dentinal micro-cracks after removal of the filling material using the TotalFill BC bioceramic-based root canal sealer through microcomputed tomography (micro-CT) analyzes. Methodology Twenty mesial roots of mandibular molars were filled with gutta-percha and TotalFill BC sealer and then the filling material was removed. The specimens were scanned by micro-CT, before instrumentation, after filling and after removal of the filling material. Subsequently, the transversal images of the mesial roots obtained after filling were analyzed and compared with that obtained after removal of the filling material, using the program Image J. Results Among the 24.444 cross sections analyzed, 5,67% presented some type of defect, with 0.51% in the initial images, 2.58% in the post-filling images and 2.58% in the final images. In the analysis comparing the initial images with the post-filling, 1,65% of the sections presented new microcracks. All the dentin defects identified in the analysis of the images obtained after the removal of the filling material were already present in the corresponding images obtained after the filling. Therefore, no new microcrack was observed after removal of the filling material. Conclusion The study did not visualize the production of new dentin microcracks during the removal of filling material in the endodontic retreatment. (AU)

Effect of surface finishing on the colour stability and translucency of dental ceramics.

BACKGROUND: The purpose of this study was to investigate the effects of staining solutions and surface finishing on the colour stability and translucency of hybrid ceramic (HC) and resin nanoceramic (RNC) materials. METHODS: Twenty four groups consisting of 10 specimens (240 specimens in total) were created out of HC and RNC, including six groups to be stored in distilled water served as the controls groups. The Vita Enamic technical set, Shofu polishers, medium and fine rubber wheels and Sof-Lex polishing discs were used as polishing instruments. Cola, tea, and coffee were used as staining solutions. The colour differences (∆E*) and translucency parameter (TP) were evaluated by a spectrophotometer. Data were analysed by a One-way Analysis of Variance (ANOVA) and Mann-Whitney U test. RESULTS: There was a statistically significant difference between the ∆E* values of the HC specimens in the coffee groups and the ∆E* values of the other HC groups (p < 0.05). The ∆E* values of the RNC specimens in the coffee and tea groups were not different from the specimens in the cola groups (p > 0.05). The TP values of the polished groups were higher than the Sof-Lex groups and the Shofu groups on both HC and RNC materials (p < 0.05). CONCLUSIONS: Increased ∆E* values were observed in HC specimens stored in a coffee solution compared to the specimens stored in a tea or cola solution. Both of the RNC specimens stored in coffee and tea had higher ∆E* values than the RNC specimens stored in the cola. The TP values of both HC and RNC specimens stored in the coffee solution decreased.

In vitro Fracture strength and hardness of different computer-aided design/computer-aided manufacturing inlays.

OBJECTIVE: The purpose of this study was to examine the fracture strength and surface microhardness of computer-aided design/computer-aided manufacturing (CAD/CAM) materials in vitro. MATERIALS AND METHODS: Mesial-occlusal-distal inlays were made from five different CAD/CAM materials (feldspathic ceramic, CEREC blocs; leucite-reinforced ceramic, IPS Empress CAD; resin nano ceramic, 3M ESPE Lava Ultimate; hybrid ceramic, VITA Enamic; and lithium disilicate ceramic, IPS e.max CAD) using CEREC 4 CAD/CAM system. Samples were adhesively cemented to metal analogs with a resin cement (3M ESPE, U200). The fracture tests were carried out with a universal testing machine. Furthermore, five samples were prepared from each CAD/CAM material for micro-Vickers hardness test. Data were analyzed with statistics software SPSS 20 (IBM Corp., New York, USA). RESULTS: Fracture strength of lithium disilicate inlays (3949 N) was found to be higher than other ceramic inlays (P < 0.05). There was no difference between other inlays statistically (P > 0.05). The highest micro-Vickers hardness was measured in lithium disilicate samples, and the lowest was in resin nano ceramic samples. CONCLUSION: Fracture strength results demonstrate that inlays can withstand the forces in the mouth. Statistical results showed that fracture strength and micro-Vickers hardness of feldspathic ceramic, leucite-reinforced ceramic, and lithium disilicate ceramic materials had a positive correlation.

Evaluation of five CAD/CAM materials by microstructural characterization and mechanical tests: a comparative in vitro study.

BACKGROUND: Polymer infiltrated ceramics and nano-ceramic resins are the new restorative materials which have been developed in order to enhance the adverse properties of glass-matrix ceramics and resin composites. The aim of the present in vitro study was to evaluate the characteristics of various CAD/CAM materials through mechanical, microstructural, and SEM analysis. METHODS: Five test groups (n = 22) were formed by using the indicated CAD/CAM blocks: VITA Enamic (VITA Zahnfabrik), Lava Ultimate (3 M ESPE), IPS e.max CAD (Ivoclar Vivadent), IPS Empress CAD (Ivoclar Vivadent), and VITA Mark II (VITA Zahnfabrik). Two specimens from each test group were used for XRD and EDS analysis. Remaining samples were divided into two subgroups (n = 10). One subgroup specimens were thermocycled (5 °C to 55 °C, 30s, 10,000 cycles) whereas the other were not. All of the specimens were evaluated in terms of flexural strength, Vickers hardness, and fracture toughness. Results were statistically analyzed using two-way ANOVA, one-way ANOVA, Tukey's HSD, and Student's t tests (α = .05). Fractured specimens were evaluated using SEM. RESULTS: The highest Vickers microhardness value was found for VITA Mark II (p < .001), however flexural strength and fracture toughness results were lowest conversely (p < .05). IPS e.max CAD was found to have the highest flexural strength (p < .001). Fracture toughness of IPS e.max CAD was also higher than other tested block materials (p < .001). Lava Ultimate and VITA Enamic's mechanical properties were affected negatively from thermocycling (p < .05). Microhardness, flexural strength, and fracture toughness values of Lava Ultimate and VITA Enamic were found to be similar to VITA Mark II and IPS Empress CAD groups. CONCLUSIONS: It should be realised that simulated aging process seem to affect ceramic-polymer composite materials more significantly than glass ceramics.

The Studies of Archaeological Pottery with the Use of Selected Analytical Techniques.

Modern analytical methods play an important role in archaeological objects, including ceramics. This review focuses on the use of analytical methods such as: gas chromatography coupled mass spectrometry, Fourier transform infrared spectroscopy, time-of-flight secondary ion mass spectrometry (ToF-SIMS), powder X-ray diffraction with thermal analysis to study the chemical and mineralogical composition of archaeological samples and organic residues preserved inside. In this paper, special attention was paid to the ToF-SIMS method, which allows the determination of characteristic ions on the surface of ceramic samples.

Biphasic calcium phosphates bioceramics (HA/TCP): Concept, physicochemical properties and the impact of standardization of study protocols in biomaterials research.

Biphasic calcium phosphates (BCP) bioceramics have become the materials of choice in various orthopedic and maxillofacial bone repair procedures. One of their main advantages is their biodegradation rate that can be modified by changing the proportional ratio of the composition phases. For enhanced bone tissue regeneration, the bioactivity of BCP should be increased by optimizing their physicochemical properties. To date, the ideal physicochemical properties of BCP for bone applications have not been defined. This is mostly related to lack of standard study protocols in biomaterial science especially with regards to their characterizations and clinical applications. In this paper we provided a review on BCP and their physicochemical properties relevant to clinical applications. In addition, we summarized the available literature on their use in animal models and evaluated the influences of different composition ratios on bone healing. Controversies in literature with regards to ideal composition ratio of BCP have also been discussed in detail. We illustrated the discrepancies in study protocols among researchers in animal studies and emphasized the need to develop and follow a set of generally accepted standardized guidelines. Finally; we provided general recommendations for future pre-clinical studies that allow better standardization of study protocols. This will allow better comparison and contrast of newly developed bone substitute biomaterials that help further progress in the field of biomaterial science.

Measuring the resistance of different substructure materials by sticking them to dentine with two different resin cements in vitro.

INTRODUCTION: The resistance of three different substructure materials - metal (Cr-Co), zirconium (Zr), and ceramics (IPS Empress II) - was measured by sticking them to dentine with two different resin cements, a dual-cure resin cement (Panavia F 2.0 Light) and a self-adhesive resin cement (BisCem). MATERIALS AND METHODS: In an in vitro study, 72 central upper front teeth were selected with no decay or apparent breakage and with complete development, removed for periodontal reasons. Labial and incisal surfaces of all teeth were prepared. Molds were obtained to prepare metal (Co-Cr), Zr, and ceramic (IPS Empress II) blocks for use in the study. The compressive strengths of the obtained material infrastructures were examined after thermal cycle processing by performing cementation to the teeth with two different cements. The data obtained were analyzed statistically. The Mann-Whitney U-test was used for comparisons of the groups with two options, and Kruskal-Wallis variance analysis was used to compare more than two groups. P<0.05 were considered statistically significant. RESULTS: While the highest result between samples was 117.86 ± 47.94 N in the dual-cure (Panavia)-ceramic group, the lowest value was observed at 6.53 ± 3.12 N in the self-adhesive (BisCem)-metal group. There was a significant difference between dual-cure (Panavia) and self-adhesive (BisCem) groups. CONCLUSION: In this study, we measured the bond strength; our most durable resistance groups were found to be, in order, Panavia-ceramics >Panavia-metal >Panavia-Zr >self-adhesive-ceramics >self-adhesive-Zr >and self-adhesive-metal.

Fracture toughness of two lithium disilicate dental glass ceramics.

STATEMENT OF PROBLEM: IPS e.max CAD and IPS e.max Press (Ivoclar Vivadent AG) are lithium disilicate glass ceramics marketed as interchangeable materials indicated for the same clinical uses. However, different crystal sizes of lithium disilicate are formed during the processing of each of these materials, a factor that could lead to significantly different mechanical properties. As mechanical failure is always associated with a crack-initiation/crack-propagation process, fracture toughness (KIC) values could be useful in comparing different ceramics and possibly predicting clinical performance. PURPOSE: The purpose of this in vitro study was to determine and compare the KIC of IPS e.max CAD and IPS e.max Press. MATERIAL AND METHODS: The notchless triangular prism (NTP) specimen KIC test was used to determine and compare the KIC of IPS e.max Press and IPS e.max CAD. Twenty 6×6×6×12-mm NTP specimens of each material were prepared. IPS e.max CAD blocks were cut, ground, and then crystallized, while IPS e.max Press specimens were prepared by pressing IPS e.max Press ingots into molds obtained from 6×6×6×12-mm wax prisms, using the lost wax technique. Each specimen was mounted into a specimen holder, and custom grips were used to attach the specimen holder assembly to a computerized universal testing machine (model 4301; Instron Canada, Inc). The assembly was loaded in tension at a crosshead speed of 0.1 mm/min, and the KIC value was calculated based on the recorded maximum load at fracture. Fractured surfaces were characterized using scanning electron microscopy (SEM). Results were statistically analyzed using Weibull statistics and the Student t test (α=.05). RESULTS: Significantly (P<.05) higher KIC value was determined for IPS e.max Press than for IPS e.max CAD and, based on the Weibull modulus (m), IPS e.max Press was also more reliable. Fractured surfaces, characterized by SEM, showed a marked difference between the 2 materials, suggesting a more complete crystallization in IPS e.max Press, which was most likely responsible for the higher KIC determined. CONCLUSION: Within the limitations of this in vitro study, the results suggest that IPS e.max Press is superior to IPS e.max CAD with regard to the KIC and characteristic Weibull parameters.

Adhesive strength of total knee endoprostheses to bone cement - analysis of metallic and ceramic femoral components under worst-case conditions.

Evaluation of the adhesive strength of femoral components to the bone cement is a relevant parameter for predicting implant safety. In the present experimental study, three types of cemented femoral components (metallic, ceramic and silica/silane-layered ceramic) of the bicondylar Multigen Plus knee system, implanted on composite femora were analysed. A pull-off test with the femoral components was performed after different load and several cementing conditions (four groups and n=3 components of each metallic, ceramic and silica/silane-layered ceramic in each group). Pull-off forces were comparable for the metallic and the silica/silane-layered ceramic femoral components (mean 4769 N and 4298 N) under standard test condition, whereas uncoated ceramic femoral components showed reduced pull-off forces (mean 2322 N). Loading under worst-case conditions led to decreased adhesive strength by loosening of the interface implant and bone cement using uncoated metallic and ceramic femoral components, respectively. Silica/silane-coated ceramic components were stably fixed even under worst-case conditions. Loading under high flexion angles can induce interfacial tensile stress, which could promote early implant loosening. In conclusion, a silica/silane-coating layer on the femoral component increased their adhesive strength to bone cement. Thicker cement mantles (>2 mm) reduce adhesive strength of the femoral component and can increase the risk of cement break-off.

Preparation and characterisation of ceramic-based thoron sources for thoron calibration chamber.

The aim of this study is to explore the correlations between the properties of the source's material and the thoron flux produced. This means a complex procedure that involves morphological characterisation (the determination of specific surface area and pore size distribution) and thoron emanation and exhalation measurements as well. In this work, the preparation of 27 thoron sources has been carried out. Three types of ceramics with different morphological properties were used as a matrix material with three different thorium contents. Spheres were formed from the dollop, and they were fired at different temperatures (200, 600 and 900°C). The phase analysis of the samples was performed by powder X-ray diffraction. The pore size distribution was determined by mercury penetration. The thoron emanation was measured using an accumulation chamber; the measured thoron emanation coefficients were from 0.34 ± 0.03 to 7.69 ± 0.13 %. Based on the results, the preparation parameters of the thoron source optimised for the calibration procedure have been given.

A unified in vitro evaluation for apatite-forming ability of bioactive glasses and their variants.

The aim of this study was to propose and validate a new unified method for testing dissolution rates of bioactive glasses and their variants, and the formation of calcium phosphate layer formation on their surface, which is an indicator of bioactivity. At present, comparison in the literature is difficult as many groups use different testing protocols. An ISO standard covers the use of simulated body fluid on standard shape materials but it does not take into account that bioactive glasses can have very different specific surface areas, as for glass powders. Validation of the proposed modified test was through round robin testing and comparison to the ISO standard where appropriate. The proposed test uses fixed mass per solution volume ratio and agitated solution. The round robin study showed differences in hydroxyapatite nucleation on glasses of different composition and between glasses of the same composition but different particle size. The results were reproducible between research facilities. Researchers should use this method when testing new glasses, or their variants, to enable comparison between the literature in the future.

Optimization of Bi2O3, TiO2, and Sb2O3 doped ZnO-based low-voltage varistor ceramic to maximize nonlinear electrical properties.

In ZnO-based low voltage varistor, the two essential features of microstructure determining its nonlinear response are the formation Bi-enriched active grain boundaries as well as a controlled ZnO grain size by secondary spinel-type phases. Besides, the microstructure and phase composition are strongly affected by the dopant concentration during sintering process. In this study, the optimal dopant levels of Bi2O3, TiO2, and Sb2O3 to achieve maximized nonlinear electrical property (alpha) were quantified by the response surface methodology (RSM). RSM was also used to understand the significance and interaction of the factors affecting the response. Variables were determined as the molar ratio of Bi2O3, TiO2, and Sb2O3. The alpha was chosen as response in the study. The 5-level-3-factor central composite design, with 20 runs, was used to conduct the experiments by ball milling method. A quadratic model was established as a functional relationship between three independent variables and alpha. According to the results, the optimum values of Bi2O3, TiO2, and Sb2O3 were obtained 0.52, 0.50, and 0.30, respectively. Under optimal conditions the predicted alpha (9.47) was calculated using optimal coded values from the model and the theoretical value is in good agreement with the value (9.43) obtained by confirmation experiment.

Effects of repeated processing on the strength and microstructure of a heat-pressed dental ceramic.

STATEMENT OF PROBLEM: The excess material produced after heat pressing a lithium disilicate glass ceramic restoration can be either discarded or reused. The reuse of this material requires that any degradation of the material quality be investigated. PURPOSE: The purpose of this study was to investigate the number of times that leftover lithium disilicate material can be re-pressed and to determine the effect that repeated use has on material properties. MATERIAL AND METHODS: A large (6.1 g) lithium disilicate ingot (A3.5) was heat pressed to yield a ceramic disk (15 × 1.5 mm) for testing. The leftover material was reused to produce a further 3 disks, with the number of pressings increasing for each specimen. An additional unpressed group was included to investigate the properties before pressing so that, in total, 5 groups were established. Specimens were tested for biaxial flexural strength, Vickers hardness, and fracture toughness. X-ray diffraction was used to characterize the crystalline phase, scanning electron microscopy for the microstructure, and differential scanning calorimetry for the thermal properties. RESULTS: No significant difference was found in the biaxial flexural strength of the groups. The hardness of the material decreased, and no significant difference was seen in fracture toughness with repeated pressings. An increase in grain size was observed with increased pressings. By using x-ray diffraction analysis, lithium disilicate was identified as the main crystal phase, and no difference in crystalline composition was found with repeated processing. CONCLUSION: This material can be reused while maintaining good mechanical properties and without significantly altering the chemical or crystalline composition in an adverse manner.

A 3-dimensional accuracy analysis of chairside CAD/CAM milling processes.

STATEMENT OF PROBLEM: Milling is a central and important aspect of computer-aided design and computer-aided manufacturing (CAD/CAM) technology. High milling accuracy reduces the time needed to adapt the workpiece and provides restorations with better longevity and esthetic appeal. The influence of different milling processes on the accuracy of milled restorations has not yet been reviewed. PURPOSE: The purpose of this study was to investigate the influence of different milling processes on the accuracy of ceramic restorations. MATERIAL AND METHODS: Four groups of partial crowns were milled (each n = 17): Three groups in a 4-axial milling unit: (1) 1-step mode and Step Bur 12S (12S), (2) 1-step mode and Step Bur 12 (1Step), (3) 2-step mode and Step Bur 12 (2Step), and (4) one group in a 5-axial milling unit (5axis). The milled occlusal and inner surfaces were scanned and superimposed over the digital data sets of calculated restorations with specialized difference analysis software. The trueness of each restoration and each group was measured. One-way ANOVA with a post hoc Tukey test was used to compare the data (α = .05). RESULTS: The highest trueness for the inner surface was achieved in group 5axis (trueness, 41 ± 15 µm, P<.05). The 4-axial milling unit exhibited trueness at settings ranging from 61 µm (2Step) to 96 µm (12S). For the occlusal surface, the highest trueness was achieved with group 5axis (trueness, 42 ± 10 µm). The 4-axial milling unit exhibited trueness at settings ranging from 55 µm (1Step) to 76 µm (12S). CONCLUSIONS: Restorations milled with a 5-axial milling unit have a higher trueness than those milled with a 4-axial milling unit. A rotary cutting instrument with a smaller diameter results in a more accurate milling process. The 2-step mode is not significantly better than the 1-step mode.

Clinical performance of screw- versus cement-retained fixed implant-supported reconstructions--a systematic review.

PURPOSE: To assess the survival outcomes and reported complications of screw- and cement-retained fixed reconstructions supported on dental implants. MATERIALS AND METHODS: A Medline (PubMed), Embase, and Cochrane electronic database search from 2000 to September 2012 using MeSH and free-text terms was conducted. Selected inclusion and exclusion criteria guided the search. All studies were first reviewed by abstract and subsequently by full-text reading by two examiners independently. Data were extracted by two examiners and statistically analyzed using a random effects Poisson regression. RESULTS: From 4,324 abstracts, 321 full-text articles were reviewed. Seventy-three articles were found to qualify for inclusion. Five-year survival rates of 96.03% (95% confidence interval [CI]: 93.85% to 97.43%) and 95.55% (95% CI: 92.96% to 97.19%) were calculated for cemented and screw-retained reconstructions, respectively (P = .69). Comparison of cement and screw retention showed no difference when grouped as single crowns (I-SC) (P = .10) or fixed partial dentures (I-FDP) (P = .49). The 5-year survival rate for screw-retained full-arch reconstructions was 96.71% (95% CI: 93.66% to 98.31). All-ceramic reconstruction material exhibited a significantly higher failure rate than porcelain-fused-to-metal (PFM) in cemented reconstructions (P = .01) but not when comparing screw-retained reconstructions (P = .66). Technical and biologic complications demonstrating a statistically significant difference included loss of retention (P ≤ .01), abutment loosening (P ≤ .01), porcelain fracture and/or chipping (P = .02), presence of fistula/suppuration (P ≤ .001), total technical events (P = .03), and total biologic events (P = .02). CONCLUSIONS: Although no statistical difference was found between cement- and screw-retained reconstructions for survival or failure rates, screw-retained reconstructions exhibited fewer technical and biologic complications overall. There were no statistically significant differences between the failure rates of the different reconstruction types (I-SCs, I-FDPs, full-arch I-FDPs) or abutment materials (titanium, gold, ceramic). The failure rate of cemented reconstructions was not influenced by the choice of a specific cement, though cement type did influence loss of retention.

The effect of ceramic primer on shear bond strength of resin composite cement to zirconia: a function of water storage and thermal cycling.

OBJECTIVES: The authors investigated the use of ceramic primers combined with self-adhesive resin composite cements on the shear bond strength (SBS) to zirconia and compared them with one conventional resin composite cement. METHODS: The authors divided zirconia substrates (N = 550) into three groups: RelyX Unicem Aplicap self-adhesive universal resin composite cement (3M ESPE, St. Paul, Minn.) (group A) (n = 220); G-CEM Capsule self-adhesive resin composite cement (GC Europe, Leuven, Belgium) (group B) (n = 220); and Panavia 21 with Clearfil Porcelain Bond Activator and Clearfil SE Bond primer (n = 110) (Kuraray Dental, Tokyo) used as a standard comparison (SC). The authors examined the self-adhesive resin composite cements without (0) and with (1) the use of a ceramic primer. They measured SBS initially (37°C for three hours), after water storage (37°C for one, four, nine, 16 or 25 days) and after thermal cycling (5°C and 55°C for 1,500, 6,000, 13,500, 24,000 or 37,500 cycles). The authors analyzed data by using descriptive statistics, the Mann-Whitney test, the Kruskal-Wallis test and a χ(2) test. RESULTS: Application of a ceramic primer did not result in a negative impact on SBS. Specimens in the A1 group (that is, RelyX Unicem Aplicap with ceramic primer) exhibited significantly higher SBS before and after water storage and thermal cycling compared with specimens that were not treated with a primer. The self-adhesive resin composite cements combined with ceramic primer exhibited similar or higher SBS values compared with those in the SC group at each aging duration (that is, water storage and thermal cycling). With respect to G-CEM Capsule, the authors observed a significantly positive effect of the primer after nine and 16 days' water storage and after one and four days' thermal cycling. They observed predominantly adhesive failures. CONCLUSIONS: Ceramic primer in combination with self-adhesive resin composite cement demonstrated a positive effect on SBS to zirconia and should be used for cementation. PRACTICAL IMPLICATIONS: Long-term adhesion to ceramic plays an important role in the longevity of dental restorations. Therefore, the authors recommend that clinicians use a ceramic primer when cementing zirconia restorations.