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Our case concerns a 66-year-old man. After experiencing recurrent episodes of abdominal pain, an initial CT scan, ultrasound and gastroscopy was carried out. All of which showed normal findings.As a consequence of persisting symptoms, another CT scan was performed. This scan revealed a hypodense area in the right lobe of the liver. This was interpreted as a possible haemangioma. Subsequent MRI scans indicated an intrahepatic cholangiocarcinoma. A final ultrasound-guided liver biopsy was performed and histology demonstrated epitheloid haemangioendothelioma, which was locally advanced and inoperable., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2020. No commercial re-use. See rights and permissions. Published by BMJ.)

Breast cancer is the second most common form of cancer diagnosed during pregnancy. The diagnosis and treatment of breast cancer during pregnancy requires multidisciplinary efforts to treat the cancer while protecting the foetus. Pregnancy-related changes in the breast make the diagnosis particularly challenging. Surgery is possible during all three trimesters. Chemotherapy can be administered in the second and third trimesters without increased risk of foetal malformations. Radiation, endocrine and biological therapies however, must be postponed until after delivery.

Statement of Problem: The fabrication of zirconium dioxide (ZrO2) dental prosthetic substructures requires an extended sintering process (8 to 10 hours) in a conventional oven. Microwave sintering is a shorter process (2 hours) than conventional sintering., Purpose: The purpose of this study was to compare the fracture toughness of 3 mol % Y2O3-stabilized ZrO2 sintered in a conventional or microwave oven., Material and Methods: Partially sintered ZrO2 specimens from 3 manufacturers, KaVo, Lava 3M, and Crystal HS were milled (KaVo Everest engine) and randomly divided into 2 groups: conventional sintering and microwave sintering (n=16 per group). The specimens were sintered according to the manufacturers' recommendations and stored in artificial saliva for 10 days. Fracture toughness was determined by using a 4-point bend test, and load to fracture was recorded. Mean fracture toughness for each material was calculated. A 2-way ANOVA followed by the Tukey HDS post hoc test was used to assess the significance of sintering and material effects on fracture toughness, including an interaction between the 2 factors (α=.05)., Results: The 2-way ANOVA suggested a significant main effect for ZrO2 manufacturer (P<.001). The post hoc Tukey HSD test indicated that mean fracture toughness for the KaVo ZrO2 (5.85 MPa·m(1/2) ±1.29) was significantly higher than for Lava 3M (5.19 MPa·m(1/2) ±0.47) and Crystal HS (4.94 MPa·m(1/2) ±0.66) (P<.05) and no significant difference was observed between Lava 3M and Crystal HS (P>.05). The main effect of the sintering process (Conventional [5.30 MPa·m(1/2) ±1.00] or Microwave [5.36 MPa·m(1/2) ±0.92]) was not significant (P=.76), and there was no interaction between sintering and ZrO2 manufacturer (P=.91)., Conclusions: Based on the results of this study, no statistically significant difference was observed in the fracture toughness of ZrO2 sintered in microwave or conventional ovens., (Copyright © 2013 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.)

Purpose: This study evaluated the relationship between instrumental measurements and subjective visual assessment of differences in dental porcelain translucency., Materials and Methods: Unshaded feldspathic porcelain was used with controlled amounts of tin oxide to create two groups of 12-mm diameter disks with incremental changes in opacity. Contrast ratio (CR = Yb/Yw) was determined with a spectrophotometer, and used as a measure of porcelain translucency (Group A = 0.20 to 0.40; Group B = 0.6-0.8). Within each group, there were 14 specimens with 11 CRs. Three observer groups (first year dental students, residents, faculty with >10 years of shade matching experience) were recruited to assess the translucency between porcelain disks under two lighting conditions (reflected light, transmitted light). Each subject's ability to distinguish between specimens of differing translucency was determined. Descriptive statistics and three-way ANOVA followed by a post-hoc Tukey-Kramer test were used to evaluate the translucency perception threshold (TPT) of subjects (alpha= 0.05)., Results: The overall mean TPT (DeltaC) was 0.07, while 50% of the subjects could perceive a 0.06 CR difference between porcelain specimens. Three-way ANOVA revealed a significant difference in translucency perception among the observer groups (p < 0.0001), whereas the main effects for porcelain opacity (p= 0.3038) and lighting condition (p= 0.0645) were not significant, and no significant interactions were found. Post-hoc Tukey-Kramer test indicated that the mean TPT observed in the faculty group (DeltaC = 0.04) was significantly lower than those observed in student (DeltaC = 0.09) and resident groups (DeltaC = 0.08), while there was no significant difference between students and residents., Conclusions: The overall mean TPT of all subjects was 0.07, and 50% of the study population perceived a 0.06 CR difference in translucency. Increased shade matching experience (> or =10 years) significantly improved the ability to perceive differences in translucency; however, neither the viewing condition nor porcelain opacity affected the perceived translucency threshold.

The shades of several resin composite materials are keyed to the Vita Lumin shade guide. This study was designed to determine whether different composites of the same designated Vita shade were actually similar in color. A small-area colorimeter was used to compare the L*a*b* color parameters of three hybrid resin composites--Pertac-Hybrid, Prisma AP.H, and XRV Herculite. Four Vita shades (A2, B3, C2, and D3) of each material were evaluated. Color differences (delta E values) between composites of the same designated shade ranged from 2.07 for the A2 shades of Herculite and AP.H to 7.64 for the D3 shades of Herculite and Pertac. Color differences in this range are perceptible to many observers under ideal viewing conditions.

In Part 2 of this literature review, a summary of the literature regarding the determination of acceptable cantilever lengths for fixed implant prostheses is presented. Studies examining the possible effects of biomechanical stress on both the implant prosthesis and the supporting bone are also discussed.

Purpose: Vibration from the high-speed handpiece may adversely affect the cement layer between a casting and a tooth, causing loss of retention or increased microleakage. This study assessed the effect of crown preparation on retention and microleakage of cemented cast post and cores., Materials and Methods: Post and cores were fabricated for extracted teeth and cemented. Specimens were prepared for crown restorations, varying the preparation time and the rotary diamond instrument used. After thermocycling and immersion in a dye bath, tensile unseating force and linear dye penetration were measured., Results: In general, retention decreased with increased severity of crown preparation; however, differences were not statistically significant (alpha = .05). Although the differing preparation conditions resulted in significant differences in microleakage, no consistent trends were evident., Conclusions: Crown preparation using high-speed rotary diamond abrasives of cast post and cores luted with zinc phosphate cement had no significant effect on their retention, but had varying effects on subsequent microleakage at the cement-tooth interface.

In Part 1 of this two-part literature review, the biomechanics of cantilever fixed partial dentures are reviewed. Theoretical constructs of implant biomechanics with special emphasis on implant-supported cantilevers are also discussed. Finally, an overview of the literature regarding occlusal forces generated by patients with implant-supported prostheses is presented.

Purpose: Cantilever lengths from 10 mm to 20 mm have been empirically recommended for Brånemark fixed mandibular implant prostheses. However, functional stresses generated within the framework and at the crestal bone associated with various cantilever lengths have not been well researched. The purpose of this investigation was to evaluate the strain generated within an implant-supported prosthesis and on a simulated bone surface during functional cantilever loading., Materials and Methods: A symmetrical mandibular fixed-implant framework supported by six Nobelpharma 7.0 x 4.0-mm abutments and 15.0 x 4.0-mm fixtures was fabricated. The fixtures were embedded in a simulated bone matrix of polymethyl methacrylate resin. Fourteen different arrangements of active supporting abutments were tested during 15 lb unilateral static cantilever loading 7 mm, 14 mm and 20 mm distal to the terminal abutments. T-rosette strain gauges were placed immediately distal to the terminal abutment site on the right side of the framework and on the corresponding simulated bone surface., Results: There was no difference in framework microstrain as abutment number and arrangement were varied. Microstrain distal to the terminal abutment increased significantly with increasing cantilever length. Distal abutment microstrain increased 213% (63 mu epsilon to 197 mu epsilon) when cantilever length was increased from 7 mm to 14 mm and an additional 55% (197 mu epsilon to 306 mu epsilon) when cantilever length was increased from 14 mm to 20 mm. Overall, microstrain increased 306% when cantilever length was increased from 7 mm to 20 mm. Microstrain on the framework was always tensile (positive). Microstrain at the simulated bone reached higher maximum levels than on the framework (-588 mu epsilon versus 314 mu epsilon) and was compressive in nature (negative). In contrast to framework microstrain, microstrain at the simulated bone site varied dramatically with changes in abutment arrangement. Strains observed at the simulated bone surface increased dramatically as the distance to the adjacent active abutment increased or as the anterior-posterior span of abutments decreased. Distal abutment microstrain also increased significantly at the bone site as cantilever length increased, however, percent increases were less (7 mm to 14 mm, 55%; 14 mm to 20 mm, 30%; 7 mm to 20 mm, 101%)., Conclusions: The results of this study indicate that an optimum biomechanical environment should exist when cantilever spans exceeding 7 mm are planned regardless of the number of supporting abutments. Strain transmitted to the crestal bone can be decreased by maximizing the number and anterior-posterior spread of supporting fixtures while minimizing the distance between the distal abutment and its adjacent abutment.

The purpose of this in vitro investigation was to determine the accuracy of gypsum casts produced from impressions made with polyether, polyether and impression plaster, or polyether and acrylic resin for the fabrication of osseointegrated implant prostheses. Strain gauges were attached to a master framework to determine the passivity of fit of the framework to sample casts made by the three impression techniques. Strain values were statistically compared by one way analysis of variance and Duncan's multiple range test. A statistically significant difference was found between the three impression techniques tested (p < 0.05). The results of this investigation revealed that none of the impression techniques resulted in an absolutely passive framework fit. However, of the techniques tested, the polyether alone resulted in the closest duplication of the master cast.

Textured opaque porcelains have been introduced to improve the appearance of metal ceramic restorations by increasing light refraction. This investigation compared the shear bond strength of a textured opaque porcelain with that of a conventional opaque porcelain. Opaque and body porcelains were fired onto six different alloys and the specimens were loaded to failure by applying shear force at the alloy-porcelain interface. No significant differences in bond strength were found between the textured and conventional opaque porcelains for any of the alloys tested.

One goal in metal ceramic substructure design is strengthening the restoration. This investigation compared the strength of four metal ceramic crown designs advocated in the dental literature. Metal ceramic crowns were fabricated, luted to a master die, and loaded to failure on a mechanical testing machine. Crowns with a facial veneer of porcelain covered occlusally with metal withstood significantly higher failure loads than did the other designs. These were followed by crowns having the porcelain extended to the central groove, crowns with facial porcelain veneers without occlusal metal coverage and, the weakest group, crowns with complete occlusal porcelain coverage. There were no significant differences between the latter three designs.

The effect of porcelain veneer opacity on the resultant shade of a veneer-substrate system was evaluated colorimetrically. Three groups of porcelain discs were fabricated using shade A1 Ceramco G veneer porcelain diluted with 0%, 25%, or 50% translucent porcelain. The discs were luted to a shade C4 substrate using an untinted resin composite luting agent. A custom shade guide was fabricated. All samples were analyzed with a Chrome Meter using Munsell and CIE LAB notation. ANOVA showed significant differences (P less than .05) for each coordinate in both the Munsell and CIE LAB color space for all groups. The smallest delta E*ab for all groups was noted with shade tab C2. The resultant shade was neither the shade of the porcelain (A1) nor the substrate (C4). The data indicate that the translucent porcelain has as great or greater effect on the color coordinates of the veneer-substrate system as the substrate material.

Differential loss of chrome from surface colorants during firing can make the prediction of final porcelain color difficult. This investigation was undertaken to assess the color change of nine extrinsic colorants during firing. Colorants were applied to metal-ceramic substrates, and color was measured both before and after firing using a colorimeter. CIE LAB color coordinates were obtained as a measure of the direction and quantity of color change. Color change for yellow (delta E*ab = 4.00) was significantly greater than that for the other groups (delta E*ab = 0.41-1.25). Changes in L*a*b* values for yellow samples were toward those of the controls.

Proper communication between the dentist and technician is essential for optimum clinical results. Contour requirements for multiple ceramometal restorations cannot be adequately described with a written laboratory authorization. A technique is described where this information is transmitted to the laboratory by means of a stone cast. The impression used to form the cast can be modified for use as a porcelain cutback guide for ceramometal framework fabrication.

Removable partial prosthodontic treatment requires multiple patient appointments with intermediate laboratory steps. A technique is described that allows the removable partial denture framework try-in and the impression for the altered cast to be efficiently completed in a single appointment. The method uses prefabricated custom impression trays that are readily attached to the framework after the try-in.

This study compared the dimensional change of simulated processed denture bases after relining with three resins. Thirty simulated denture bases 1.5 to 2 mm thick were processed from Lucitone 199 resin following the manufacturer's instructions using the long-cure method. Ten bases were relined with Lucitone 199 (long-cure), 10 were relined with Triad resin, and 10 were relined with Accelar 20 resin. The relined bases were processed on a metal die using a reline jig, and three measurements (from distobuccal flange to distobuccal flange) were made with a traveling microscope immediately before and after relining. Each relined simulated denture base showed a significant dimensional shrinkage after processing. The mean dimensional change values of the Triad resin relined bases were significantly greater than those of the other two resin relined bases. All of the dimensional change values, however, would probably be insignificant in a clinical situation.

Porcelains that are claimed to improve the appearance of metal ceramic restorations by increasing light refraction from a highly textured opaque surface have recently been introduced. This study compared the appearance and color of one of these opaque porcelains with a conventional smooth-surface opaque. The opaque porcelains were applied to alloy substrates, and samples were evaluated colorimetrically. After the application of body and incisal porcelains, the samples were evaluated subjectively by clinicians and again colorimetrically. Subjective determination of the most lifelike porcelain depended on the shade. Color differences existed between the opaque porcelains for all shades examined.

The purpose of this study was to evaluate the marginal adaptation of all-porcelain labial margin metal ceramic crowns using a porcelain shoulder material containing a light-polymerizing resin and one that used a direct-lift technique. Conventional metal margin restorations served as controls. Scanning electron micrographs were made of a 1-mm mesiodistal width of the margin at midfacial and midlingual reference marks. Image processing and analysis techniques were accomplished using a computer. Statistical evaluation indicated that the mean labial marginal discrepancy of the control group was significantly less than that of either of the two porcelain shoulder methods.

The effect of porcelain veneer opacity on the resultant shade of a veneer/substrate system was subjectively evaluated. Three groups of porcelain discs were fabricated using shade A1 Ceramco G veneer porcelain diluted with 0%, 25%, or 50% translucent porcelain. The discs were luted to a shade C4 substrate using an untinted composite resin luting agent. Clinicians were instructed to match samples with a custom and a commercial shade guide, and to sort veneers into groups of similar shade. The Farnsworth-Munsell 83 Hue test was used to measure the clinicians' color vision. Results indicated that the participants were unable to distinguish any difference between veneer groups (kappa = 0.33). Shade C2 was the predominant shade chosen for all groups. All veneers provided some masking of the underlying substrate. Varying the percentage of translucent porcelain had little effect on the final shade assessment.

Residual stress caused by a mismatch of alloy-porcelain thermal contraction can contribute to clinical failure of a ceramometal restoration. This investigation assessed thermal compatibility of three ceramometal alloys and two opaque porcelains. Thermal expansions of the alloys and porcelains were measured by using a straight push-rod dilatometer. Porcelain glass transition temperatures and expansion values were derived from length-versus-temperature curves. Residual stress states in alloy-porcelain pairs were assessed by comparing expansion values of the components at the porcelain glass transition temperatures. Above that temperature the porcelain viscosity is low and stress relief is possible, whereas below the glass transition the porcelain acts as a stress-supporting solid. Expansion values were in general agreement and glass transition temperatures were slightly lower than values previously reported for similar materials. Alloy-porcelain thermal compatibility for the materials tested appeared more dependent on the opaque porcelain than the alloy.