Influence of post material and ferrule thickness on the fracture resistance of endodontically treated premolars: A laboratory study.

STATEMENT OF PROBLEM: The influence of the ferrule thickness and post materials on the fracture resistance of endodontically treated teeth remains unclear. PURPOSE: The purpose of this laboratory study was to evaluate the influence of post material and ferrule thickness on the fracture resistance of endodontically treated mandibular premolars. MATERIAL AND METHODS: Sixty-four extracted and endodontically treated mandibular first premolars were used and divided into 4 test groups (n=16) depending on the ferrule thickness: F-0: without a ferrule, F-0.5: with a 0.5-mm ferrule thickness, F-1: with a 1-mm ferrule thickness, and F-1.5: with a 1.5-mm ferrule thickness. In groups with ferrules, the height ranged from 2 mm buccally/lingually to 1 mm proximally. Teeth in subgroups (n=8) were restored with either prefabricated glass fiber (FF) or titanium posts (FT) (ISO size 70 and length of 7.5 mm) and then adhesively restored with composite resin foundation materials. After foundation procedures, each specimen was restored with a cobalt chromium crown which was cemented with glass-ionomer cement. All specimens were subjected to dynamic loading in a masticatory simulator for 1 200 000 loading cycles with a nominal load of 5 Kg at 1.2 Hz and simultaneous thermocycling (5 to 55 °C). Specimens were then quasistatically loaded at 30 degrees in a universal testing machine until fracture. Fracture loads were analyzed by using 2-way ANOVA followed by the Tukey honestly significant difference test (α=.05). RESULTS: Fracture loads ranged from 610 ±45 N (no ferrule - glass fiber post) to 1216 ±169 N (1.5 mm ferrule thickness - glass fiber post). A statistically significant increase in fracture resistance was observed with increasing ferrule thickness (P<.001). However, post materials did not show a statistically significant influence (P=.977). CONCLUSIONS: Under the conditions of this laboratory study, increasing the ferrule thickness had a significant effect on the fracture resistance of endodontically treated teeth after thermomechanical fatigue, irrespective of post materials.

Accuracy and dimension stability of scannable versus conventional interocclusal registration materials: An in vitro study.

STATEMENT OF PROBLEM: Scientific data to support scannable and computer-aided design and computer-aided manufacturing (CAD-CAM)-compatible interocclusal registration materials are lacking. PURPOSE: The purpose of this in vitro study was to evaluate the ability of different registration materials (conventional versus scannable) to record maxillary-mandibular relationships and compare the dimensional stability of these records after storage times of 1 hour and 48 hours. MATERIAL AND METHODS: Six groups of interocclusal registration materials were tested: 3 conventional (Registrado X-tra, Futar D Fast, and O-Bite) and 3 scannable (Registrado Scan, Futar Cut & Trim Fast, and O-Bite Scan). Eight registrations were made for each group by using a custom-made device with a dial gauge to measure vertical discrepancies. Records were stored at room temperature, and discrepancies measured after 1 hour and 48 hours. The data were statistically analyzed with the Wilcoxon test with respect to time and the Kruskal-Wallis test with respect to materials, followed by the Mann-Whitney test with the Bonferroni-Holm correction (α=.05). RESULTS: The median vertical discrepancies ranged from -2 µm (FS) to 11 µm (O-Bite) after 1 hour and from 3 µm (Futar Cut & Trim Fast) to 13 µm (Registrado X-tra and O-Bite) after 48 hours. A statistically significant difference (P<.001) was found between the results after 1 hour and 48 hours for all materials. All scannable interocclusal registration materials showed significantly lower vertical discrepancies than the corresponding conventional materials after 1 hour and 48 hours (P<.05). CONCLUSIONS: All registration materials showed vertical discrepancies that might be clinically acceptable. Vertical discrepancies increased after 48 hours of storage for all materials but were still clinically acceptable.

The Correlation of Surface Roughness Parameters of Zirconia and Lithium Disilicate with Steatite Wear.

PURPOSE: Various surface roughness parameters are utilized to describe the surface in the tooth to ceramics abrasion and to assess the resulting wear. The use of three-dimensional parameters may offer a better estimation for wear and an improved deduced clinical surface treatment. The aim of this study was to determine the influence of various surface roughness parameters of zirconia and lithium disilicate ceramics on the wear of steatite antagonists. MATERIAL AND METHODS: Forty zirconia specimens with a diameter of 7 mm and a thickness of 3 mm and 40 lithium disilicate specimens with the dimensions 10×10×4 mm were each divided into five subgroups. Two subgroups were treated with different clinically established diamond burs; a third subgroup was treated with a silicone polishing set. Two additional subgroups were produced by glazing the surfaces after treatment. Surface roughness parameters were determined by laser scanning microscopy. All specimens underwent 1.2 million loading cycles using steatite antagonists. After regular intervals of cycles, precision impressions were made to assess the wear. The correlation between wear and different roughness parameters was evaluated using the Spearman correlation test. RESULTS: For the glazed zirconia, unglazed zirconia, and glazed lithium disilicate specimens no significant correlations (p > 0.05) between the investigated roughness parameters and antagonist wear could be found. In the unglazed lithium disilicate groups, significant (p ≤ 0.05) correlations with steatite substance loss could be found for several roughness parameters after 1.2 million cycles. CONCLUSIONS: For lithium disilicate, it seems not sufficient to use only one roughness parameter to indicate the wear behavior of the surface. There was no correlation between wear and the tested roughness parameters of zirconia surfaces.

Bond strength of adhesive luting systems to human dentin and their durability.

STATEMENT OF PROBLEM: The durability of adhesive bonding systems to dentin is of importance for restoration longevity; therefore, new adhesive systems should be tested in vitro with long-term artificial aging before clinical application. PURPOSE: The purpose of this in vitro study was to investigate the bonding durability of 3 dual-polymerizing resins and 1 autopolymerizing resin to human dentin with their specific self-etching primers or adhesives. MATERIAL AND METHODS: Acrylic resin tubes filled with composite resin were bonded to human dentin disks using either an autopolymerizing resin system (Panavia 21) or dual-polymerizing resin systems (Panavia V5, RelyX Ultimate, and Variolink Esthetic DC) together with the system-specific primer or adhesive. Tensile bond strength was tested after 3 days of water storage or after 150 days of water storage with 37 500 thermocycles (5 °C to 55 °C). The failure mode was evaluated by using a light microscope. In addition, representative specimens were examined by using a scanning electron microscope. RESULTS: After 3 days, the median tensile bond strengths ranged from 18.8 to 29.1 MPa. After artificial aging for 150 days, the median tensile bond strengths ranged from 14.7 to 25.6 MPa. The dual-polymerizing resins showed significantly higher bond strength than the autopolymerizing resin (P≤.05). Artificial aging with thermocycling had no statistically significant influence on tensile bond strength for the adhesive resin systems tested (P>.05). The failure mode was mainly adhesive for the autopolymerizing resin, whereas it was mainly cohesive for the dual-polymerizing resins. CONCLUSIONS: The 3 tested dual-polymerization resin systems provided durable bond strengths to dentin which were higher than those of the autopolymerizing resin.

An experimentally validated neural-network potential energy surface for H-atom on free-standing graphene in full dimensionality.

We present a first principles-quality potential energy surface (PES) describing the inter-atomic forces for hydrogen atoms interacting with free-standing graphene. The PES is a high-dimensional neural network potential that has been parameterized to 75 945 data points computed with density-functional theory employing the PBE-D2 functional. Improving over a previously published PES [Jiang et al., Science, 2019, 364, 379], this neural network exhibits a realistic physisorption well and achieves a 10-fold reduction in the RMS fitting error, which is 0.6 meV per atom. The chemisorption barrier is 172 meV, which is lower than that of the REBO-EMFT PES (260 meV). We used this PES to calculate about 1.5 million classical trajectories with carefully selected initial conditions to allow for direct comparison to results of H- and D-atom scattering experiments performed at incidence translational energy of 1.9 eV and a surface temperature of 300 K. The theoretically predicted scattering angular and energy loss distributions are in good agreement with experiment, despite the fact that the experiments employed graphene grown on Pt(111). Compared to previous calculations, the agreement with experiments is improved. The remaining discrepancies between experiment and theory are likely due to the influence of the Pt substrate only present in the experiment.

Influence of the preparation form on the retention of resin-bonded attachments for removable dental prostheses.

OBJECTIVES: The study evaluated the influence of the number of retention grooves and the retainer wing thickness on the retention of resin-bonded attachments (RBAs). METHODS: Overall, 64 extracted human teeth were prepared, whereby the number of retention grooves (4, 2, 1, or no grooves) and the material thickness (0.7 or 0.5 mm) of the RBAs were varied. This resulted in eight groups with eight specimens each. A sample size of eight specimens per group was chosen because the chewing simulator used for dynamic loading can load eight specimens at a time. After the size of the adhesive area was determined, the abutment teeth were provided with RBAs and subjected to a dynamic loading with thermal cycling. Finally, the failure load was examined using a retention test. RESULTS: The mean failure loads ranged from 152 ± 50 N to 228 ± 32 N. There had been a significant interaction between the two main factors, i.e., number of retention grooves and material thickness. Neither the number of retention grooves nor the size of the adhesive area had a significant influence on the failure load. CONCLUSIONS: Using a reduced number of retention grooves seems reasonable. However, clinical considerations suggest using two retention grooves to simplify the preparation and bonding procedures. CLINICAL RELEVANCE: The retention of resin-bonded attachments is promising and supports the clinical application of this minimally invasive treatment modality.

Effect of reduced airborne-particle abrasion pressure on the retention of zirconia copings resin bonded to titanium abutments.

STATEMENT OF PROBLEM: The optimal conditioning of zirconia is essential for a durable bond between zirconia copings and titanium inserts in 2-piece dental implant abutments. Low-pressure activation of the zirconia surface may be adequate for retention. PURPOSE: The purpose of this in vitro study was to evaluate the influence of airborne-particle abrasion (APA) of the zirconia surface with different pressures on the retention of zirconia copings bonded to titanium abutments. In addition, 2 luting systems were compared. MATERIAL AND METHODS: Computer-aided design and computer-aided manufacturing (CAD-CAM) zirconia copings were divided into 3 groups (n=32): 0.1 MPa, 0.25 MPa, and not airborne-particle abraded surfaces with 50-µm alumina (Al2O3) particles. Compatible titanium abutments were airborne-particle abraded at a pressure of 0.25 MPa. All specimens were ultrasonically cleaned before bonding. Each group was divided into 2 subgroups (n=16) with different luting composite resins. A 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) containing self-adhesive luting composite resin (Panavia SA Cement Plus) and a conventional luting composite resin (Multilink Hybrid Abutment) in combination with a 10-MDP-containing universal primer (Monobond Plus) was compared. Two storage conditions were tested: in water (37 °C) for 3 days or 150 days with 37 500 thermocycles between 5 °C and 55 °C. After artificial aging, retention was measured in tension, and the failure modes were analyzed by using a light microscope and a scanning electron microscope. Statistical analysis was performed with 1-way ANOVA and the Games-Howell test for post hoc analysis (α=.05). RESULTS: The mean retention of the airborne-particle abraded groups ranged from 576.0 N to 1049.3 N after 150 days of water storage and 37 500 thermocycles. No significant difference in bond strength was found between the 2 luting composite resin groups with airborne-particle abraded zirconia surfaces after 150 days (P<.05). Both bonding systems provided durable bond strength after 3 and 150 days. Failure mode was mainly cohesive at the titanium surfaces and predominantly adhesive at the zirconia surfaces. The retention was significantly higher if APA was used versus no APA (P<.05), while the APA pressure used made no significant difference. CONCLUSIONS: The APA of zirconia copings at a pressure of 0.1 MPa in combination with 10-MDP-containing luting composite resins and primers is adequate for the durable bonding of zirconia copings to titanium inserts.

Influence of post material, post diameter, and substance loss on the fracture resistance of endodontically treated teeth: A laboratory study.

STATEMENT OF PROBLEM: The influence of the flexural modulus of prefabricated posts on the fracture resistance of endodontically treated teeth is unclear. PURPOSE: The purpose of this in vitro study was to evaluate the influence of post material and post diameter on the fracture resistance of endodontically treated mandibular premolars. In addition, the influence of tooth substance loss was evaluated by comparing 1 with 2 residual dentinal walls. MATERIAL AND METHODS: Sixty-four extracted mandibular first premolars were endodontically treated and divided into 8 test groups (n=8) based on the number of residual walls (1 or 2), post material (glass fiber or titanium) and post diameter (International Standards Organization [ISO] 70 or ISO 90). After luting the posts, the specimens received a composite resin core and a crown preparation with a 2-mm ferrule. Cast Co-Cr crowns were cemented with glass ionomer cement. After 1 200 000 mastication cycles with a load of 49 N and simultaneous thermocycling (5 °C-55 °C), specimens were quasistatically loaded at 30 degrees to the longitudinal axis of the tooth until fracture. Fracture loads were analyzed by using 3-way ANOVA (α=.05). Fracture modes were examined with a stereomicroscope at ×25 magnification and recorded. RESULTS: Fracture loads ranged from 954 ±35 N (1 residual wall-glass fiber-ISO 70) to 1286 ±202 N (1 residual wall-glass fiber-ISO 90). Titanium posts showed a statistically significant higher fracture resistance than glass fiber posts. A statistically significant increase in fracture resistance was also observed with increasing post diameter. However, no significant difference was found with respect to the number of residual walls (P>.05). CONCLUSIONS: Teeth restored with titanium posts exhibited higher fracture resistance than teeth restored with glass fiber posts, especially when smaller diameter posts were used.

Bond strength durability of self-adhesive resin cements to zirconia ceramic: An in vitro study.

STATEMENT OF PROBLEM: How contamination, cleaning, and artificial aging affect the bond strength of self-adhesive resin cements to zirconia ceramics is unclear. PURPOSE: The purpose of this in vitro study was to assess the durability and bond strength of different self-adhesive resin cements to zirconia ceramics subjected to contamination, cleaning, and aging. MATERIAL AND METHODS: A total 192 zirconia ceramic squares were airborne-particle abraded with 50 µm Al2O3 at a pressure of 100 kPa. The specimens were then divided into 4 main experimental groups (n=48) according to the type of self-adhesive resin. Specimens in the subgroups (n=16) were exposed to 3 different treatment methods: alcohol bath cleaning only, contamination with saliva and alcohol bath cleaning, and contamination with saliva and cleaning with Ivoclean followed by alcohol bath cleaning. Bonded specimens were stored in distilled water (37°C), either for 3 days with no thermocycling or for 150 days interrupted by 37500 thermocycles between 5°C and 55°C. After storage, the bond strength was determined using a universal testing machine. Results were analyzed statistically, using nonparametric tests. RESULTS: After saliva contamination, the tensile bond strength for all specimens decreased significantly (P<.001). Furthermore, after saliva contamination and during 150 days of water storage with thermocycling, all specimens debonded spontaneously. However, use of the cleaning medium (Ivoclean) significantly increased the tensile bond strength for almost all specimens (P<.05). CONCLUSIONS: Saliva contamination significantly negatively influenced the bond strength and durability to zirconia ceramic. Ceramic cleaning using Ivoclean significantly improved the bond strength to saliva contaminated zirconia ceramics.

Effect of fatigue loading on the fracture strength and failure mode of lithium disilicate and zirconia implant abutments.

OBJECTIVE: The aim of this study was to test five types of implant restorations using titanium, zirconia and lithium disilicate abutments after being subjected to long-term fatigue loading. MATERIALS AND METHODS: Forty single-tooth implant restorations were assembled on titanium implants (FairTwo; FairImplant). The restorations differed only in the type of abutment used and were divided into five groups [Ti: titanium; Zr: zirconia with no metal base; ZrT: zirconia with titanium base; LaT: lithium disilicate abutment with titanium base; and LcT: lithium disilicate hybrid-abutment-crown with titanium base]. Specimens were subjected to dynamic load of 49 N up to 1,200,000 cycles using a dual-axis chewing simulator (Kausimulator; Willytech). The surviving specimens were subjected to quasi-static loading using a universal testing machine (Z010; Zwick) until the implant-abutment connection failed. The values of force (N) at which fracture or plastic deformation of the restoration occurred were calculated and the rate of deformation was analyzed. The data was then analyzed using Mann-Whitney tests. RESULTS: Groups Ti, ZrT, LaT and LcT withstood 1,200,000 fatigue load cycles and higher forces than physiological occlusal forces without fracture or debonding of the ceramic suprastructure. In group Zr, some specimen did not survive the chewing simulation and this group showed the lowest resistance to failure with a median of 198 N. CONCLUSIONS: Within the limitations of this study, it could be concluded that lithium disilicate abutments and hybrid-abutment-crowns show promising durability and strength after long-term dynamic loading. The use of titanium base enhances the strength of the zirconia abutments.

Efficacy of Plasma Treatment for Decontaminating Zirconia.

PURPOSE: To evaluate the influence of contamination and plasma treatment on the bond strength of resin to zirconia ceramic. MATERIALS AND METHODS: After immersion in saliva or the use of a silicone disclosing agent, polished and airborne-particle abraded zirconia specimens were cleaned either ultrasonically in 99% isopropanol or with nonthermal plasma. Uncontaminated zirconia specimens were used as control. For chemical analysis, specimens of all groups were examined with x-ray photoelectron spectroscopy (XPS). Plexiglas tubes filled with composite resin were bonded to ceramic specimens with a phosphate-monomer-containing luting resin. The influence of contamination and cleaning methods on ceramic bond durability was examined by tensile testing after 3 and 150 days of water storage, with an additional 37,500 thermocycles during the 150-day storage. RESULTS: XPS showed an increase in the amount of oxygen and a decrease in the amount of carbon on the zirconia surface after plasma treatment. After contamination with silicone, XPS revealed a high amount of Si residue on the surface that none of the investigated cleaning processes could completely remove. The tensile bond strength to uncontaminated zirconia ceramic was durable, but was significantly reduced by contamination. CONCLUSION: Plasma treatment was effective in removing salivary contamination but not silicone disclosing agent residue from the bonding surface of zirconia.

Durability of Resin Bonding to Lithium Disilicate and Zirconia Ceramic using a Self-etching Primer.

PURPOSE: The purpose of this in vitro study was twofold: 1. To evaluate the surface conditioning effect of a self-etching ceramic primer on lithium disilicate and zirconia ceramics; (2) to study the bond durability provided by the self-etching ceramic primer after artificial aging compared with conventional ceramic conditioning methods. MATERIALS AND METHODS: Lithium disilicate blocks (10 × 10 mm, 3.4 mm thick) and zirconia disks (8 mm diameter, 3.4 mm thick) were each divided into two groups. In group 1, the lithium disilicate disks (Li) were etched with hydrofluoric acid (HF), while zirconia (Zr) disks were treated with airborne-particle abrasion, both followed by application of a universal primer for restorative materials (MP; Monobond Plus, Ivoclar Vivadent). In group 2, Li disks were not etched with HF, while Zr disks were treated with airborne-particle abrasion, both followed by a self-etching primer (ME; Monobond Etch & Prime, Ivoclar Vivadent). Surface conditioning effects were evaluated using SEM. The specimens in both groups were bonded to a composite with a luting resin and divided into two subgroups. Subgroup 1 was stored in water (37°C) for 3 days, and subgroup 2 was stored in water for 30 days before undergoing 7500 thermal cycles (5°C to 55°C). RESULTS: The self-etching ceramic primer had a significant effect only on the lithium disilicate surface topography. The mean initial bond strength of ME-Zr was relatively low (24.4 MPa) in comparison with all other material combinations (MP-Li: 34.3 MPa; ME-Li: 33.5 MPa; MP-Zr: 31.1 MPa). After 30 days of water storage and thermocycling, the bond strength decreased significantly in all groups. CONCLUSION: The self-etching primer provided bond strengths to lithium disilicate ceramic comparable with those of the well-established bonding method using hydrofluoric acid etching and a primer containing silane. To zirconia ceramic, however, it provided statistically significantly lower bond strength than did the established bonding method.

Comparison of fracture strength and failure mode of different ceramic implant abutments.

STATEMENT OF PROBLEM: The whitish color of zirconia (ZrO2) abutments offers favorable esthetics compared with the grayish color of titanium (Ti) abutments. Nonetheless, ZrO2 has greater opacity, making it difficult to achieve natural tooth color. Therefore, lithium disilicate (LaT) abutments have been suggested to replace metal abutments. PURPOSE: The purpose of this in vitro study was to evaluate the fracture strength and failure mode of single-tooth implant restorations using ZrO2 and LaT abutments, and to compare them with titanium (Ti) abutments. MATERIAL AND METHODS: Five different types of abutments, Ti; ZrO2 with no metal base; ZrO2 with a metal base (ZrT); LaT; and LaT combination abutment and crown (LcT) were assembled on 40 Ti implants and restored with LaT crowns. Specimens were subjected to quasistatic loading using a universal testing machine, until the implant-abutment connection failed. As bending of the metal would be considered a clinical failure, the values of force (N) at which the plastic deformation of the metal occurred were calculated, and the rate of deformation was analyzed. Statistical analysis was done using the Mann-Whitney U test (α=.05). RESULTS: Group ZrO2 revealed the lowest resistance to failure with a mean of 202 ±33 N. Groups ZrT, LaT, and LaC withstood higher forces without fracture or debonding of the ceramic suprastructure, and failure was due to deformation of metal bases, with no statistically significant differences between these groups regarding the bending behavior. CONCLUSIONS: Within the limitations of this in vitro study, it was concluded that LaT abutments have the potential to withstand the physiological occlusal forces that occur in the anterior region and that ZrO2 abutments combined with Ti inserts have much higher fracture strength than pure ZrO2 abutments.

Active surveillance in localized prostate cancer: comparison of incidental tumours (T1a/b) and tumours diagnosed by core needle biopsy (T1c/T2a): results from the HAROW study.

OBJECTIVE: To conduct a comparative prospective analysis of patients with incidental T1a/T1b prostate cancer (IPCa) and those with prostate cancer (PCa) diagnosed by core needle biopsy, treated by active surveillance (AS), with regard to inclusion criteria, progression and switch to deferred treatment. PATIENTS AND METHODS: The HAROW study is an observational outcomes research study on the management of localized PCa. Treating urologists reported clinical variables and information on therapy and clinical course of disease at 6-month intervals. With respect to therapy, only recommendations were made; the final decision on the therapeutic method rested with the treating physician. RESULTS: Out of 2 957 patients included in the HAROW study, 447 chose AS. The median follow-up was 28.3 months. T1a, T1b, T1c and T2a disease were diagnosed in 81, 18, 292 and 56 patients, respectively. Patients in the IPCa group had lower prostate-specific antigen (PSA) levels (4.2 vs 6.1 ng/mL) and more comorbidities than those diagnosed by core needle biospy. The IPCa group also had fewer re-biopsies (25.3 vs 43.2%) and fewer changes to invasive treatment (12.1 vs 25.9%). No significant differences were found with respect to the criteria for discontinuation, subsequent therapies and histological findings after radical prostatectomy. CONCLUSION: Urologists are highly inclined to use AS as a therapeutic option in IPCa. More patients with IPCa than those diagnosed after core needle biopsy continued on AS, which was also associated with the indication for a re-biopsy being less stringently observed.

Analysis of topographical distribution of prostate cancer and related pathological findings in prostatectomy specimens using cMDX document architecture.

INTRODUCTION: Understanding the topographical distribution of prostate cancer (PCa) foci is necessary to optimize the biopsy strategy. This study was done to develop a technical approach that facilitates the analysis of the topographical distribution of PCa foci and related pathological findings (i.e., Gleason score and foci dimensions) in prostatectomy specimens. MATERIAL & METHODS: The topographical distribution of PCa foci and related pathologic evaluations were documented using the cMDX documentation system. The project was performed in three steps. First, we analyzed the document architecture of cMDX, including textual and graphical information. Second, we developed a data model supporting the topographic analysis of PCa foci and related pathologic parameters. Finally, we retrospectively evaluated the analysis model in 168 consecutive prostatectomy specimens of men diagnosed with PCa who underwent total prostate removal. The distribution of PCa foci were analyzed and visualized in a heat map. The color depth of the heat map was reduced to 6 colors representing the PCa foci frequencies, using an image posterization effect. We randomly defined 9 regions in which the frequency of PCa foci and related pathologic findings were estimated. RESULTS: Evaluation of the spatial distribution of tumor foci according to Gleason score was enabled by using a filter function for the score, as defined by the user. PCa foci with Gleason score (Gls) 6 were identified in 67.3% of the patients, of which 55 (48.2%) also had PCa foci with Gls between 7 and 10. Of 1173 PCa foci, 557 had Gls 6, whereas 616 PCa foci had Gls>6. PCa foci with Gls 6 were mostly concentrated in the posterior part of the peripheral zone of the prostate, whereas PCa foci with Gls>6 extended toward the basal and anterior parts of the prostate. The mean size of PCa foci with Gls 6 was significantly lower than that of PCa with Gls>6 (P<0.0001). CONCLUSION: The cMDX-based technical approach facilitates analysis of the topographical distribution of PCa foci and related pathologic findings in prostatectomy specimens.

Effect of surface treatments on the properties and morphological change of dental zirconia.

STATEMENT OF PROBLEM: Creating a rough surface for bonding with airborne-particle abrasion with alumina may damage the surface of zirconia. Other treatment methods for creating a bonding surface without causing damage require investigation. PURPOSE: The purpose of this in vitro study was to find ways of treating the zirconia surface without causing flaws, debris, pits, microcracks, or tetragonal to monoclinic phase transformation. MATERIAL AND METHODS: Yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) ceramic surfaces were treated with gas plasma, argon-ion bombardment, 150-µm abrasive zirconia particles, and abrasive 150-µm alumina particles; untreated surfaces were used as the control group. X-ray diffraction (XRD) and confocal Raman spectroscopy were used to study the phase transformation. The roughness of specimens was measured with a confocal 3D laser scanning microscope. Modification of surface topography was analyzed with field emission scanning electron microscopy (FESEM), and the flexural strength was measured with a universal testing machine. Statistical analyses were performed with 1-way ANOVA, followed by comparison of means with the Tukey honest significant difference test. The standard deviation was calculated with descriptive statistics. RESULTS: The sintered Y-TZP ceramic used in this study showed 2 phases, tetragonal and cubic. Specimens abraded with 150-µm alumina particles showed a higher monoclinic volume fraction (VmXRD=8.68%) and roughness (Ra=0.91µm) than specimens abraded with 150-µm zirconia particles (VmXRD=1.22%, Ra=0.08µm). One-way ANOVA indicated a significance difference in roughness among groups (P<.01). No phase transformation was observed in specimens treated with argon-ion bombardment or plasma. According to the Raman results, the volume fraction of the monoclinic phase for the specimens treated with airborne-particle abrasion depended on the distance from the ceramic surfaces and decreased with the increase in this distance. A slightly higher flexural strength was observed for untreated specimens (1009 MPa), followed by specimens treated with gas plasma (1000 MPa) and those airborne-particle abraded with 150-µm zirconia particles (967 MPa). The flexural strength of other specimens was lower (940 MPa for specimens abraded with 150-µm alumina particles and 916 MPa for specimens subjected to argon-ion bombardment). One-way ANOVA analysis indicated no significant difference in flexural strengths among all groups (P>.2). FESEM measurements showed that airborne-particle abrading Y-TZP surfaces with 150-µm alumina particles caused more damage to this area than the other methods. CONCLUSIONS: Y-TZP ceramic surfaces treated with zirconia particles, argon-ion bombardment, and gas plasma were damaged less in comparison with surfaces abraded with alumina particles.

Development of Composite Poly(Lactide-co-Glycolide)- Nanodiamond Scaffolds for Bone Cell Growth.

There are relatively few nanotechnologies that can produce nanocomposite scaffolds for cell growth. Electrospinning has emerged as the foremost method of producing nanofibrous biomimetic scaffolds for tissue engineering applications. In this study diamond nanoparticles were integrated into a polymer solution to develop a nanocomposite scaffold containing poly(lactide-co-glycolide) (PLGA) loaded with diamond nanoparticles. To investigate the effect of adding diamond nanoparticles to PLGA scaffolds, primary human mesenchymal stem cells (hMSCs) were seeded on the scaffolds. The cytocompatibility results showed that addition of diamond nanoparticles did not impinge upon cell proliferation, nor was there a cytotoxic cellular response after 9 days in culture. Scanning electron microscopy, transmission electron microscopy, atomic force microscopy and confocal microscopy enabled qualitative characterization of the fibres and revealed cell morphology and number. Furthermore, surface roughness was measured to evaluate diamond nanoparticle modifications, and no significant difference was found between the diamond nanocomposite and pure polymer scaffolds. On the other hand, bright spots on phase images performed by atomic force microscopy suggested a higher hardness at certain points on fibers of the PLGA-nanodiamond composites, which was supported by nanoindentation measurements. This study shows that PLGA nanofibers can be reinforced with nanodiamond without adversely affecting cell behaviour, and thus it sets the foundation for future application of these scaffolds in bone tissue engineering.

Treatment of Incidental Prostate Cancer by Active Surveillance: Results of the HAROW Study.

OBJECTIVE: To report on a cohort of patients with incidental prostate cancer (IPC) that was treated by an active surveillance (AS) protocol in the HAROW study. MATERIALS AND METHODS: The HAROW study is an observational study on the management of localized prostate cancer in Germany. Treating urologists were reporting clinical parameters, information on therapy and clinical course of disease at 6-month intervals. RESULTS: In total, 3,169 patients were enrolled. In 224 patients were found an IPC and 104 (46%) of them were put on an AS protocol. The mean follow-up was 26.5 months. Tumor progression was noted in 16 patients. In 11 patients, AS was replaced by a definite intervention. In univariate and multivariate analyses, only PSA density correlated with progression. CONCLUSION: This is the first prospective description of an IPC patient cohort on AS as part of an outcomes research study. AS was selected as a therapeutic strategy in nearly half of the patients (46%). Only a minor proportion (16%) displayed progression. Of the clinical parameters, only PSA density correlated with progression.

Effect of differences in coefficient of thermal expansion of veneer and Y-TZP ceramics on interface phase transformation.

STATEMENT OF PROBLEM: The stability of veneering ceramics requires further investigation. PURPOSE: The purpose of this study was to investigate, with Raman spectroscopy, the occurrence and extent of the tetragonal to monoclinic phase transformation in yttria partially stabilized tetragonal polycrystalline zirconia (Y-TZP) ceramic at the veneer-framework interface. MATERIALS AND METHODS: Three different Y-TZP blanks Cercon base, ZENO TEC, and Zerion were used. The specimens were sintered according to the recommendations of the manufacturers (1350°C Cercon base, 1450°C ZENO TEC, and 1500°C Zerion for 2 hours). Three veneer ceramics with different coefficients of thermal expansion, Cercon ceram kiss, Zirox, and VITA VM9 were used to veneer the Y-TZP frameworks. For the investigation of the temperature gradient on the phase transformation of Y-TZP ceramic, some specimens were fractured, with a universal testing machine along the long axis of the coping. RESULTS: No evidence was found for the presence of the tetragonal to monoclinic phase transformation for nonabraded and nonveneered specimens. The tetragonal to monoclinic phase transformation was observed at the veneer-framework interface for all veneered specimens and was dependent on the sintering temperature of the framework. The highest volume fractions of the monoclinic phase at the veneer-framework interface amounted to 0.57 (Cercon base), 0.69 (ZENO TEC), and 0.72 for the Zerion framework. The tetragonal to monoclinic phase transformation was not homogenous along the veneer-framework interface and depended on the distance from the cross section of the veneer-framework interface. The greatest tetragonal to monoclinic transformation was observed at the interface and disappeared with increasing distance from it. For the veneered Cercon base specimens, the volume fraction of the monoclinic phase decreased from 0.53 to 0.13 over a distance of 20 µm. No phase transformation was observed at a distance that exceeded 20 µm from the cross section of the veneer-framework interface. CONCLUSION: This study demonstrated that the firing process of veneer ceramic and the difference in the coefficients of thermal expansion between the ceramic framework and the veneer ceramic significantly influenced the stability of the tetragonal phase of Y-TZP ceramic at the veneer-framework interface.

The Influence of Contamination and Different Cleaning Methods and the Effect of Plasma Treatment of CoCr Alloy on Tensile Bond Strength to Composite Resin.

PURPOSE: To investigate the influence of contamination and different cleaning methods on resin bonding to cobalt-chro- mium (CoCr) alloy disks. MATERIALS AND METHODS: A total of 160 CoCr disks were divided into 3 groups. The first group (N = 64) was air abraded with alumina particles and contaminated with a silicone disclosing agent and saliva; the second group (N = 64) was air abraded but not contaminated; the third group (N = 32) was neither air abraded nor contaminated. The first two groups were di- vided into 4 subgroups (N = 16) according to the cleaning method: ultrasonic bath in 99% isopropanol, use of a cleaning suspension of zirconium oxide particles, use of a cleaning suspension based on 10-MDP salt, and treatment with atmo- spheric plasma. The third group was divided into 2 subgroups (N = 16): treatment with atmospheric plasma and no treat- ment. All CoCr specimens were bonded to plexiglas tubes filled with a bonding resin that contained phosphate monomer. Tensile bond strength (TBS) was examined by tensile testing after 3 and 150 days of water storage plus 37,500 thermal cy- cles (N = 8). RESULTS: After contamination, TBS was significantly reduced after 150 days of water storage. Groups without air abrasion showed initially low TBS and debonded spontaneously after 150 days of water storage. CONCLUSION: None of the cleaning methods was able to remove saliva and silicone disclosing agent on CoCr-alloy sur- faces. Surface activation by plasma treatment has no long-term effect on the bond strength.