Effect of preheating and ultrasound application of resin-based luting agents on the failure load of a lithium disilicate glass-ceramic

PURPOSE

To assess the effect of preheating resin-based materials and ultrasound application on the failure load of a lithium disilicate glass-ceramic.

MATERIALS AND METHODS

Ninety ceramic specimens were produced (14×12×1.0 mm) and divided into 9 groups (n = 10) to be bonded to a dentin analog (Nema G10) with light-cured luting agent (LC), flowable resin composite (FL), and supra-nano filled resin composite (SN), as follows: LC/R - LC at room temperature; LC/P - preheated LC; LC/P/U - preheated LC and Ultrasound; FL/R - FL at room temperature; FL/P - preheated FL; FL/P/U - preheated FL and Ultrasound; SN/R - SN at room temperature; SN/P - preheated SN; SN/P/U - preheated SN and Ultrasound. The failure load test was performed in a universal testing machine with the aid of acoustic detection. The data was analyzed with two-way ANOVA (for failure load) and Weibull statistics (Weibull modulus - m and characteristic strength, based on 95% confidence intervals - CI).

RESULTS

The analyses of failure load revealed no statistically significant difference among groups considering the type of luting agent (P = 0.075; F = 2,673), the application method (P = 0.772; F = 2,259), and the interaction between them (P = 0.297; F = 1,248). The characteristic strength did not show differences among groups (95% CI). The m, which indicates structural reliability, showed lower values for SN/P/U and SN/P, with a difference from other selected groups (95% CI).

CONCLUSION

Preheating of resin-based materials and ultrasound application did not affect the failure load of lithium disilicate glass-ceramic. Lower reliability was observed with supra-nano filled resin composite.

The distribution of marginal excess cement of implant-supported vented and non-vented zirconia crowns with and without cleaning procedures

PURPOSE

To investigate the distribution of marginal excess cement in vented and non-vented crowns and evaluate the effect of clinical cleaning procedures on the reduction of excess cement.

MATERIALS AND METHODS

Forty models with implant analogs in the position of the right maxillary first molar were divided into four groups (n = 10/group, vented/non-vented crowns with or without cleaning procedures). The abutment finish lines were placed 1 mm below the artificial gingiva buccally, mesially, and distally and at the gingival level palatally. A standardized amount (20 mg) of resin cement was applied in a thin layer to the intaglio surface of zirconia vented and non-vented crowns. The excess cement was removed by a dental explorer in groups with cleaning procedures. The distribution (area and depth) of the marginal excess cement was measured at each quadrant (buccal, mesial, palatal, and distal) for all study samples. The data were analyzed using descriptive and analytical statistics (ɑ = 0.05).

RESULTS

The area and depth values of the excess cement in each quadrant in the vented group were significantly smaller than that in the non-vented group, both with and without cleaning (p < 0.001). Cleaning procedures significantly reduced the area of excess cement in both vented and non-vented groups (all, p < 0.001 except for p < 0.05 at the buccal aspect of the vented group). The depth of excess cement in the vented group was significantly decreased with cleaning in the buccal quadrant compared with that without cleaning (p < 0.01). However, the depth of excess cement of the non-vented group was significantly increased with cleaning in all quadrants compared with that without cleaning (all, p < 0.001 except for p < 0.05 at the distal aspect).

CONCLUSIONS

Crown venting significantly reduced the area and depth of the marginal excess cement in vitro. Cleaning procedure with a dental explorer significantly reduced the area of marginal excess cement in vitro; however, the excess cement can be pushed deeper in the non-vented group.

Influence of cement type, excess removal, and polishing on the cement joint

OBJECTIVES

To compare marginal gap width and depth with different cementation systems, excess removal, and after polishing.

METHOD AND MATERIALS

In total, 80 composite crowns were milled, divided into ten groups, and cemented on identical artificial teeth. Eight crowns per group were fixed with (i) zinc phosphate cement (ZnOPh), (ii) glass-ionomer cement (GIC), (iii) resin-reinforced glass-ionomer cement (GIC mod), (iv) dual-curing adhesive composite (Comp dual), or (v) dual-curing self-adhesive composite (Comp SE dual). Excess removal was performed with a scaler after brief light-cure (tack-cure), final light-cure, during rubber or gel phase or by wiping with foam pellet. Curing was completed in chemical, dark cure, or light-curing modus. The specimens were polished and stored in water (37°C). The margins were digitized using a 3D laser-scanning microscope (VK-X100 series, Keyence). The width and the depth of the marginal gap were measured at 10 points between the crown margin and the preparation margin.

RESULTS

The width after excess removal varied between 65.1 ± 15.7 µm (Comp dual, wipe, with polishing) and 208.6 ± 266.7 µm (Comp SE dual, dark cure, without polishing). The depth varied between 29.8 ± 22.2 µm (Comp dual, wipe, with polishing) and 89.5 ± 45.2 µm (Comp SE dual, dark cure, without polishing). The impact on gap width and depth was detected for fixation material, excess removal, and polishing.

CONCLUSION

The gap depth and width depend on the luting material and the mode of access removal. Polishing can improve the gap quality, especially for GIC and resin-based systems.

Technique for cementing screwmentable implant crowns to prevent misalignment

The purpose of this article is to describe a technique to accurately cement implant crowns on an abutment extraorally and prevent misalignment that might change the desired position of the crown on the abutment when delivered. An implant-retained crown was tried-in and occlusal and interproximal contacts were adjusted for delivery. The cementation verification aid was fabricated using a polyvinylsiloxane bite registration material (Blu Mousse) to cement the crown onto the abutment extraorally to ensure proper alignment of the crown on the abutment. Cementation of the prosthesis occurred with no adjustments required to the interproximal or occlusal contacts during final delivery. This article provides a technique that aims to increase accuracy in the placement of the crown on the abutment when cementing screwmentable crowns.

The Effect of Restoration Thickness on the Fracture Resistance of 5 mol% Yttria-Containing Zirconia Crowns

BACKGROUND

To determine what thickness of 5 mol% yttria zirconia (5Y-Z) translucent crowns cemented with different cements and surface treatments would have equivalent fracture resistance as 3 mol% yttria (3Y-Z) crowns.

METHODS

The study included 0.8 mm, 1.0 mm, and 1.2 mm thickness 5Y-Z (Katana UTML) crowns and 0.5 and 1.0 mm thickness 3Y-Z (Katana HT) crowns as controls. The 5Y-Z crowns were divided among three treatment subgroups (n = 10/subgroup): (1) cemented using RMGIC (Rely X Luting Cement), (2) alumina particle-abraded then luted with the same cement, (3) alumina particle-abraded and cemented using a resin cement (Panavia SA Cement Universal). The 3Y-Z controls were alumina particle-abraded then cemented with RMGIC. The specimens were then loaded in compression at 30° until failure.

RESULTS

All 5Y-Z crowns (regardless of thickness or surface treatment) had a similar to or higher fracture force than the 0.5 mm 3Y-Z crowns. Only the 1.2 mm 5Y-Z crowns with resin cement showed significantly similar fracture force to the 1 mm 3Y-Z crowns.

CONCLUSION

In order to achieve a similar fracture resistance to 0.5 mm 3Y-Z crowns cemented with RMGIC, 5Y-Z crowns may be as thin as 0.8 mm. To achieve a similar fracture resistance to 1.0 mm 3Y-Z crowns cemented with RMGIC, 5Y-Z crowns must be 1.2 mm and bonded with resin cement.

Printed abutment model to limit residual cement: a dental technique

Preventing retained cement around implant-retained crowns is crucial in the long-term health and success of the implant. Residual subgingival cement is strongly associated with peri-mucositis and can lead to peri-implantitis. This clinical technique utilizes a 3D printed model of a custom abutment to seat the implant crown on before cementing intra-orally to extrude excess cement. The technique aims to limit the amount of retained cement at the crown-abutment margin and also takes into consideration the cement space already designed into the crown-abutment complex. This article is protected by copyright. All rights reserved.

Etch-and-rinse versus self-etch strategy of a universal adhesive in different application methods at the bonding interface of fiber post cementation

OBJECTIVE

To evaluate the effect of etch-and-rinse (ER) versus self-etch (SE) strategies of a universal adhesive applied with a manual brush (MB) or rotary brush (RB) on the bonding interface of fiber post cementation.

METHODS

Forty bovine incisor roots were prepared and divided into four groups according to the methods of application and strategy of universal adhesive use (MB-ER, RB-ER, MB-SE and RB-SE). After 6 months, specimens from different thirds of the post space were evaluated of push-out strength, analysis of adhesive failure patterns, and extent of tags.

RESULTS

The RB-ER and RB-SE groups showed the highest bond strength values in the cervical and middle thirds of the post space. Cohesive adhesive failure had the highest incidence in the different thirds of the post space in the ER strategy, regardless of the adhesive application method. The RB-ER group showed the highest tag extensions.

CONCLUSIONS

The protocols of universal adhesive application with RB provided the greater bond strength, but only the ER strategy favored the formation of a greater extension of tags at the adhesive interface.

CLINICAL SIGNIFICANCE

The application of universal adhesive with RB into the post space increases the strength of the post-cemented fiber bond.

Endocrowns: Indications, Preparation Techniques, and Material Selection

Endodontic treatment is often necessary in the field of dentistry. As the tooth structure is lost during such treatment, the tooth may become weaker and lose some of its mechanical qualities. Endodontically treated posterior teeth require cuspal coverage because of their anatomical features. Endocrowns are regarded as a suitable choice for restoring teeth that have undergone endodontic treatment. These restorations are recommended when there is a substantial loss of tooth structure, restricted interocclusal space, or a short clinical crown. They are also contraindicated in case of severe loss of tooth structure where adhesion is not applicable. Endocrowns require a specific preparation design that is distinct from the conventional crown. They can be manufactured by two methods: heat pressing or computer-aided design/computer-aided manufacturing (CAD/CAM). Moreover, several materials have been used in fabricating endocrown restoration. Lithium disilicate glass-ceramic is the most recommended material as it possesses excellent mechanical properties and esthetic results with the ability to bond to tooth structure. In conclusion, several kinds of literature recommend using them for molars. Further research is needed to evaluate this technique for premolar and anterior teeth.

Cementing Techniques In Knee Surgery (CeTIKS): a UK expert consensus study

Aims

Aseptic loosening is the most common cause of failure following cemented total knee arthroplasty (TKA), and has been linked to poor cementation technique. We aimed to develop a consensus on the optimal technique for component cementation in TKA.

Methods

A UK-based, three-round, online modified Delphi Expert Consensus Study was completed focusing on cementation technique in TKA. Experts were identified as having a minimum of five years' consultant experience in the NHS and fulfilling any one of the following criteria: a 'high volume' knee arthroplasty practice (> 150 TKAs per annum) as identified from the National joint Registry of England, Wales, Northern Ireland and the Isle of Man; a senior author of at least five peer reviewed articles related to TKA in the previous five years; a surgeon who is named trainer for a post-certificate of comletion of training fellowship in TKA.

Results

In total, 81 experts (round 1) and 80 experts (round 2 and 3) completed the Delphi Study. Four domains with a total of 24 statements were identified. 100% consensus was reached within the cement preparation, pressurization, and cement curing domains. 90% consensus was reached within the cement application domain. Consensus was not reached with only one statement regarding the handling of cement during initial application to the tibial and/or femoral bone surfaces.

Conclusion

The Cementing Techniques In Knee Surgery (CeTIKS) Delphi consensus study presents comprehensive recommendations on the optimal technique for component cementing in TKA. Expert opinion has a place in the hierarchy of evidence and, until better evidence is available these recommendations should be considered when cementing a TKA.

Circulating Flow-Electric-Field-Configuration-Enhanced Cadmium Cementation from Sulfate Systems and Its Optimization Mechanism

In this work, a novel flow-electric field coupling configuration was designed and implemented for enhancing Zn-Cd cementation. A series of tests was conducted to explore the optimization of the Zn-Cd cementation process and its mechanism. Firstly, the various characteristics of the sponge cadmium at various locations in the device were compared, and it was concluded that the optimum purity of the sponge cadmium obtained from the anode was up to 94.1%. The generation and stripping of the cadmium sponge was revealed for the first time by cross-sectional electron microscopy. The four stages of the apparent reaction in the system were analyzed in relation to the pH, cadmium concentration and cadmium sponge flaking at each flow rate. It was proved that the separation of cadmium sponge mainly occurred in the third phase. Secondly, by comparing the morphology and specific surface area of the cadmium sponge at different flow rates, the optimum flow field velocity was identified as 30 mL/s. At this point, the specific surface area reached a maximum of 1.151 m2/g. Six flow field configurations were compared and preferred. The results demonstrated that the LCAH (Low-Cathode-Anode-High) modulation resulted in a sparser structure of the cadmium sponge, which was more easily exfoliated from the zinc anode surface by fluid impact. This was considered to be the most beneficial flow field configuration for improving the cadmium cementation rate and reducing the cost of the reaction. Moreover, the reaction steps of the system were analyzed. Its rate-limiting step was initially empirically identified as the diffusion step and proven by calculating the activation energy of 12.6 kJ/mol. It was confirmed that the diffusion process under different flow field configurations followed the first-order kinetic principle. In addition, the system's reaction phases were compared. Calculations confirmed that the diffusion process under various flow field configurations followed first-order kinetics. The diffusion coefficient of LACH proved to be the highest in the comparative tests, and the evident experimental results supported this conclusion.

The Rare Occurrence of Giant Cell Tumor of the Proximal Tibia With Pathological Fracture in an Elderly Male: A Case Report

Giant cell tumor of the bone (GCTB) is a benign bone tumor that can occasionally progress to malignancy, usually in chronic cases. It is a common benign and aggressive bone tumor that affects patients aged between 20 and 45 years. The most common location is the knee joint. It manifests as a painless or occasionally painful swelling over the affected area. A case of giant cell tumor (GCT) of the proximal tibia in a 72-year-old male is reported here, which was difficult to diagnose as it is rarely found in the geriatric age group. The patient came with a chief complaint of pain and swelling over his left knee for two months with a history of trauma to the knee a couple of times. On clinical examination, the patient had grade 3 tenderness and swelling on the anterolateral aspect of the knee extending toward the proximal tibia. The swelling was well-defined, smooth, firm, and uniform in consistency with dimensions of 15 cm × 12 cm. The swelling was moveable sideways, and the movement of the knee suggested that it was not attached to the underlying bone. As per the age and history of the rapid-growing lesion, we suspected malignancy, but clinical findings were pointing toward benign tumor. X-ray of the affected knee was done, which revealed a soft tissue mass with the involvement of the bone. Magnetic resonance imaging (MRI) of the knee revealed a soft tissue mass with the cortical breach. An open biopsy was done for the confirmation of the diagnosis, which was later reported and confirmed as a giant cell tumor of the proximal tibia. As bone tumor is associated with a cortical breach and pathological fracture, it was classified under Campanacci grade 3, for which an en bloc resection and open reduction and internal fixation with plate osteosynthesis with bone cementing and bone grafting were done followed by knee bending physiotherapy and gradual weight-bearing. Finally, the knee function was improved with pain relief.

Effect of irrigation acid solutions on cleaning and bond strength to post-space dentin

This study evaluated the effects of irrigating solutions containing 5% boric acid + 1% citric acid or 1% peracetic acid + high concentration hydrogen peroxide on root cleaning and bond strength of cementation systems after 24 h and 6 months of glass fiber post cementation. One hundred and twenty roots were endodontically treated. The specimens were randomized into one of four treatments (n = 10): DW (distilled water); NaOCl2.5% + EDTA17% (2.5% sodium hypochlorite solution + 17% EDTA); PA1% + HP (1% peracetic acid solution + high concentration of hydrogen peroxide); BA5% + CA1% (5% boric acid associated with 1% citric acid). The cleaning efficacy in the cervical, middle, and apical thirds of the post-space, and the push-out bond strength at 24 h and 6 months after post cementation were evaluated by Kruskal-Wallis and two-way ANOVA tests, respectively. BA5% + CA1% showed statistically significantly superior cleaning efficacy compared to the other solutions. This irrigation protocol also resulted in higher bond strength at 24 h and 6 months, regardless of the root third considered, and this was statistically significantly higher than those seen for DW and PA1% + HP. For BA5% + CA1% irrigation protocol, type 1 adhesive failure was the most prevalent. Post-space irrigation with BA5% + CA1% provided both higher cleaning efficacy and better bond strength.

Removal of Impurities from EAFD Ammonium Carbonate Leachate and Upgrading the Purity of Prepared ZnO

The paper describes cementation as a suitable method applied in the refining of EAFD leachates in order to obtain required purity of ZnO for specific industrial application. For study of cementation conditions, the leachate from alkaline leaching with (NH₄)₂CO₃ was used. The leachates contained a high amount of zinc (8000-12,000 µg/mL) and a low content of impurities such as iron, lead, copper, chromium and manganese in the range of 1-21 µg/mL. Cementation conditions were predicted by thermodynamic study, theoretically confirming the viability of the proposed experiments at the considered pH = 8-9. Cementation experiments were carried out using powdered zinc and aluminium (5 g/L) as cementation agents in the first phase separately. To increase the cementation efficiency, their combination was used (2.5:2.5 g/L or 5:5 g/L) at temperatures of 20, 40, 60 and 80 °C for 30 min. The optimum cementation conditions were established as: Zn:Al = 5:5 g/L, 60 °C. Under the given conditions, 100% of Fe, Cu, Pb and Mn were removed from the leachate. The ZnO with the maximum purity of 96.67% was obtained by crystallization of cemented leachate at 105 °C, followed by calcination at 900 °C for 4 h. ZnO with such a purity is suitable for use in the electrical or rubber industries.

Investigation of the Bimodal Leaching Response of RAM Chip Gold Fingers in Ammonia Thiosulfate Solution

Oxidative thiosulfate leaching using Cu(II)-NH₃ has been explored for both mining and recycling applications as a promising method for Au extraction. This study seeks to understand the dissolution behavior of Au from waste RAM chips using a Cu(II)-NH₃-S₂O₃ solution. In the course of this work, bimodal leaching and Au loss were observed in a manner that we have not identified in the literature. Identification of the existence of a specific Au-Ni-Cu lamellar structure in the gold fingers from RAM chips by scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDS) revealed the possibility of interference between Au recovery and the existence of Cu and Ni. During leaching, the co-extraction of Ni was found to predict a negative impact on the Au recovery, as a result of chemical interactions from the Au-Ni-Cu interlayer. Decopperization as a pretreatment was found necessary to remove the pre-existing Cu and promote Au leaching. As part of the study parameters, such as Cu(II) concentration, aeration rates, thiosulfate and ammonia concentrations, particle sizes, and temperatures, were investigated. A satisfactory Au recovery of 98% was achieved using 50 mM Cu(II), 120 mL/min aeration rate, 0.5 M (NH₃)₂S₂O₃, and 0.75 M NH₄OH (i.e., AT/AH ratio of 0.67) for 4 h residence time at room temperature (25 °C). However, there were several high recoveries prior to Au loss from the lixiviant. It was revealed that the main cause of lower Au recovery was due to a precipitation or cementation reaction that included a sulfur species formation. Because of the bimodal leaching, a composite response comprised of the time to Au loss and maximum recovery was developed, termed leaching proclivity, to facilitate statistical analysis. Furthermore, this study explores the interactions between Au-Ni-Cu and provides suggestions for improving Au thiosulfate leaching under the interference of co-existing metals from waste PCB materials.

Risk Factors with Porcelain Laminate Veneers Experienced during Cementation: A Review

The clinical success of porcelain laminate veneers (PLVs) depends on many clinical and technical factors, from planning to execution, among which adhesive cementation is of significant importance. This procedure carries many risk factors if not optimally executed. The objective of this study was to document the clinical parameters affecting successful cementation procedures with a focus on the adhesive strength, integrity, and esthetics of the PLVs. A literature search was conducted through MEDLINE, complemented by a hand search using predefined keywords. Articles published in English between 1995 and 2023 were selected. According to this review, the success and longevity of PLVs rely in great part on the implementation of a precise cementation technique, starting from field isolation, adequate materials selection for adhesion, proper manipulation of the materials, the seating of the veneers, polymerization, and elimination of the excess cement. Several clinical steps performed before cementation, including treatment planning, preparation, impression, and adequate choice of the restorative material, could affect the quality of cementation. Scientific evidence suggests careful implementation of this process to achieve predictable outcomes with PLVs. The short- and long-term clinical success of adhesively luted PLVs is tributary to a deep understanding of the materials used and the implementation of clinical protocols. It is also contingent upon all the previous steps from case selection, treatment planning, and execution until and after the cementation.

In Vitro Investigation of Material Combinations for Meso- and Suprastructures in a Biomimetic Approach to Restore One-Piece Zirconia Implants

The aim of this study was to find a suitable material combination to avoid cement excess in the marginal region of one-piece zirconia implant-supported restorations by means of a hybrid crown consisting of a meso- and a suprastructure. One-piece zirconia implants (n = 120) were embedded in epoxy resin. Microfilled resin composite mesostructures (n = 60), designed as caps, were bonded on the implant abutment with a primer only. A molar crown was constructed and cemented with a resin cement on top of the mesostructure as a suprastructure out of feldspar ceramic (n = 12), lithium-disilicate (n = 24), or zirconia (n = 24). Fracture load (n = 6) and retention force (n = 6) were measured immediately after storage in distilled water at 37 °C for 24 h, as well as after an additional exposure to artificial aging in a chewing simulator and simultaneous thermal cycling. For the measurement of the fracture load, monolithic crowns made of the employed restorative materials and identical in shape to the hybrid crowns served as controls (n = 6 each). Fracture load values for feldspar ceramic and lithium-disilicate hybrid crowns were slightly higher than those for the respective monolithic crowns at baseline and after aging, which was statistically significant only for feldspar crowns after aging. In contrast, fracture load values for zirconia monolithic crowns were higher than those for zirconia hybrid crowns, which was only statistically significant after aging. Artificial aging reduced the fracture load of feldspar and lithium-disilicate crowns both for hybrid and monolithic crowns. The effect was only statistically significant for lithium disilicate hybrid crowns. The fracture load for hybrid and monolithic zirconia crowns was increased by artificial aging without reaching statistical significance. The retention force of lithium-disilicate and zirconia hybrid crowns was not affected by artificial aging. Taking into account retention force and fracture load, lithium-disilicate hybrid crowns showed promising results.

Impact of polyethylene glenoid cementation technique on cement mantle integrity and stability after cyclic loading: a computed tomography and biomechanical study

BACKGROUND

There are no generally accepted guidelines for polyethylene (PE) glenoid component cementation techniques. In particular, it is not known whether the backside of a PE glenoid should be fully or partially cemented-or not cemented at all. We hypothesized that cementing techniques would have an impact on cement mantle volume and integrity, as well as biomechanical stability, measured as micromotion under cyclic loading.

METHODS

To address our hypothesis, 3 different cementation techniques using a single 2-peg PE glenoid design with polyurethane foam were compared regarding (1) the quality and quantity of the cement mantle and (2) biomechanical stability after cyclic loading in vitro. Eight identically cemented glenoids per group were used. Group A underwent cement application only into the peg holes, group B received additional complete cement mantle application on the backside of the glenoid, and group C received the same treatment as group B but with additional standardized drill holes in the surface of the glenoid bone for extra cement interdigitation. All glenoids underwent cyclic edge loading by 10⁵ cycles according to ASTM F2028-14. Before and after loading, cement mantle evaluation was performed by XtremeCT and biomechanical strength and loosening were evaluated by measuring the relative motion of the implants.

RESULTS

The cement mantle at the back of the implant was incomplete in group A as compared with groups B and C, in which the complete PE backside was covered with a homogeneous cement mantle. The cement mantle was thickest in group C, followed by group B (P = .006) and group A (P < .001). We did not detect any breakage of the cement mantle in any of the 3 groups after testing. Primary stability during cyclic loading was similar in all groups after the "running-in" phase (up to 4000 cycles). Gross loosening did not occur in any implant.

CONCLUSIONS

Coverage of the PE glenoid with cement was reproducible in the fully cemented groups (ie, groups B and C) as compared with relevant cement defects in group A. The addition of cement to the back of the PE glenoid and additional drill holes in the glenoid surface did not improve primary stability in the tested setting.

Long-Term Outcomes of Cementing Highly Cross-Linked Polyethylene Liners Into Well-Fixed Acetabular Shells in Revision Total Hip Arthroplasty

BACKGROUND

Cementing a new liner into a secure, well-positioned metallic shell can be a less-invasive strategy in revision total hip arthroplasty (THA). This study aimed to report the mean 14-year outcomes of cementing highly cross-linked polyethylene (XLPE) liners into well-fixed acetabular shells in revision THAs.

METHODS

This study reviewed a single-surgeon series of cementing XLPE liners into well-fixed acetabular components. Of the 52 hips (51 patients) evaluated, 48 hips (47 patients) that satisfied a minimum follow-up of 10 years were included. The Harris Hip score was used for clinical evaluation. Final hip radiographs were used to determine the extent of acetabular osteolysis and stability of the components. The mean age at index operation was 53 years (range, 32 to 72). The mean follow-up duration was 14 years (range, 10 to 18).

RESULTS

The mean Harris Hip score improved from 58 points (range, 23-81) preoperatively to 91 points (range, 45-100) at the final evaluation (P < .001). A total of 3 acetabular rerevisions were performed, all for aseptic loosening of the outer shell. One postoperative dislocation occurred, but it was successfully treated with a closed reduction. Final radiographs showed a significant reduction in acetabular osteolysis (P < .001). Implant survivorship free from any rerevision was 93.3% (95% confidence interval, 85.9-100%) at 14 years.

CONCLUSION

Cementing an XLPE liner into a well-fixed acetabular shell in revision THA demonstrated excellent clinical and radiographic outcomes at a mean of 14 years postoperatively. This technique could be a safe and durable option in the absence of XLPE liners compatible with preimplanted shells.

Isolated Liner Exchange in Total Hip Arthroplasty at a Mean of 13 Years of Follow-up: Does Fixation Technique Matter?

BACKGROUND

Isolated liner exchange is an option to address polyethylene wear after total hip arthroplasty (THA). The liner can be fixed with either the original locking mechanism or cemented into the acetabular cup. Whether the method used for liner fixation has any bearing on the outcomes in the first and second decade after surgery is still unclear.

METHODS

Data for all patients who had undergone isolated liner exchange surgery in our institution between April 1995 and January 2015 were retrieved. Patients were classified according to the type of polyethylene liner (conventional or highly crosslinked polyethylene) and the locking mechanism used (original locking mechanism or cemented). Survivorship and revision rates were compared among different subgroups. A total of 118 isolated liner exchanges were performed and patients had a mean duration of follow-up of 13 years (range, 5 to 25).

RESULTS

Overall estimated mean survivorship was 17 years. Use of highly crosslinked polyethylene (HXLPE) had a lower re-revision rate compared to conventional liners (10.5 versus 46.9%) (P < .001). The re-revision rate of exchanges using HXLPE was not affected by the type of fixation (original locking mechanism 11.1 versus cement 10.0%, P = .868). Conversely, using the original locking mechanism with a conventional liner had a higher re-revision rate compared to cemented conventional liners (58.3 versus 12.5%) (P = .024).

CONCLUSION

HXLPE liners should be used in insert exchange surgery whenever possible. Re-revision rate of exchanges using HXLPE was not affected by the fixation technique used. Cementing an insert into an acetabular component is associated with good survivorship at a mean of 13 years follow-up.

Intralesional curettage and cementation of low-grade chondrosarcomas of the appendicular skeleton: Long-term results from a single center

OBJECTIVE

The purpose of this study was to investigate the results and complications in patients who had low-grade chondrosarcomas in the appendicular skeleton and were treated by intralesional curettage and cementation within the scope of 25 years of experience in a single center.

METHODS

Ninety-one patients (72 female and 19 male) were retrospectively analyzed. The median at the time of surgery was 43 (17-78) years, and the median follow-up was 102 (26-288) months. All patients were treated by intralesional curettage followed by cementation with high-viscosity bone cement (polymethylmethacrylate). Complications and local recurrence rates, as well as clinical outcome scores were recorded.

RESULTS

Five patients (5.49%) developed local recurrence at an average of 6.6 (6-9) months postoperatively. Four were treated with local wide excision and reconstruction with tumor prosthesis. One patient received recurettage and cementation. Two recurred patients were dedifferentiated into grade II chondrosarcomas in the last intervention. No major postoperative complication was identified in the series. Patients achieved an average Musculoskeletal Tumor Society scoring system of 92.4% (standard deviation 5.2; range 80-100) in the sixth postoperative month. Musculoskeletal Tumor Society scores in the recurrent patients decreased from an average of 90% to 75.3% after the final intervention.

CONCLUSION

Intralesional curettage and cementation seem safe and reliable techniques with low recurrence and complication rates in treating low-grade chondrosarcomas of the appendicular skeleton. Clinical, radiological, and pathological evaluations are mandatory before surgical intervention, and a multidisciplinary approach is crucial. A strict follow-up regimen in the early postoperative period is needed and strongly recommended to detect local recurrence.

LEVEL OF EVIDENCE

Level IV, Therapeutic Study.

Effect of Vent Hole and Cement Type on Fracture Resistance of CAD-CAM Monolithic Zirconia Crowns

PURPOSE

To assess the fracture resistance of monolithic zirconia crowns cemented with different types of cement on cement-retained implant abutments.

MATERIALS AND METHODS

Forty implant analogues were positioned in acrylic resin blocks, and cement-retained straight implant abutments were fastened to the analogues. Crowns were designed with/without occlusal vent holes and produced from monolithic zirconia blocks by the CAD-CAM technique. The two crown types were divided into two groups and cemented with resin and zinc-polycarboxylate cement under 5 kg weight. A universal testing machine applied compressive forces to the crowns until fracture. Fracture resistance values were analysed using two-way ANOVA and the independent samples t-test with statistical significance set at p < 0.05.

RESULTS

According to the two-way ANOVA results, although the crown design did not have a significant effect on fracture resistance (1417.65 ±337.39 N, 1565.16 ±517.12 N; crowns with and without vent holes, respectively), the main effect of the cement variable on the fracture resistance was significant. Zinc-polycarboxylate cement (1680.1 ±375.23 N) showed higher fracture resistance than resin cement (1302.71 ±420.64 N) in the crowns designed with vent holes (p< 0.005).

CONCLUSION

The use of cement-retained implant-supported monolithic zirconia crowns with an occlusal vent hole is safe, and zinc-polycarboxylate cement use may be an appropriate choice for cementation of these crowns. This article is protected by copyright. All rights reserved.

Luting indirect restorations with resin cements versus composite resins: Effects of preheating and ultrasound energy on film thickness

OBJECTIVE

This study aims to evaluate and compare the film thickness obtained with a resin cement and two composite resins, preheated and/or ultrasonically vibrated, as luting agents.

MATERIALS AND METHODS

One hundred and twenty-six (126) pairs of resin discs were randomly assigned to six experimental groups (n = 21) according to luting agent (Variolink Esthetic LC, IPS Empress Direct or Estelite Omega) and cementation technique (preheating at 68°C and/or ultrasonic vibration). Specimens were luted by applying a controlled force. Following sectioning and film thickness measurement through field emission gun scanning electron microscopy, statistical analysis was carried out considering a 5% significance level.

RESULTS

Statistically significant lower film thickness was observed in Variolink Esthetic LC group when compared to all composite resin groups (p < 0.001), except IPS Empress Direct preheated and ultrasonically vibrated group (p = 0.073). IPS Empress Direct with ultrasonic vibration yielded statistically lower film thickness values than Estelite Omega groups, regardless of luting technique (p < 0.05). Ultrasonically vibrated Estelite Omega groups showed statistically lower film thickness values than solely preheated groups (p < 0.05).

CONCLUSIONS

Both Variolink Esthetic LC and IPS Empress Direct preheated and ultrasonically vibrated provided the lowest film thickness. The addition of ultrasonic vibration during cementation proved to be effective in reducing film thickness of both tested composite resins.

CLINICAL SIGNIFICANCE

The cementation technique will have variable results depending on the luting material. Adhesive cementation protocols with composite resins should mainly consider ultrasonic vibration, but also preheating, as strategies for reducing film thickness. The tested resin cement, alongside with IPS Empress Direct composite resin preheated and ultrasonically vibrated, provided the lowest film thickness among the tested materials and techniques.

Management of Giant Cell Tumor of Talus With Extended Intralesional Curettage and Reconstruction Using Polymethylmethacrylate Cement

An 18-year-old man presented with complaints of pain and swelling around the left ankle region. Local examination revealed diffuse, hard, mildly tender swelling with ill-defined margins over the medial aspect of the left ankle joint just below the medial malleolus. Radiographic and computed tomographic assessment revealed osteolytic lesion with moderately defined margins. Provisional diagnosis of Campanacci grade 2 giant cell tumor was made, which was later confirmed on histopathology. Extended intralesional curettage and reconstruction with polymethylmethacrylate cement was done under spinal anesthesia. Full weight bearing was allowed at 4 weeks when the below knee back slab was removed. Radiographic assessment was done every 3 months during the first year of follow-up and then every 6 months. No evidence of recurrence of tumor, collapse of talus, or avascular necrosis was found during follow-up. Managing such rare form of bone tumors with extended intralesional curettage and bone cement is an appropriate treatment and gives good functional results.Level of Evidence: Level V.

The Effect of Commercially Available Desensitizers on Bond Strength Following Cementation of Zirconia Crowns Using Self-Adhesive Resin Cement-An In Vitro Study

The improvement of the tensile strength of zirconia crowns after the application of commercially available desensitizers can provide added advantages for the durability and strength of zirconia prostheses. We assessed the retention of zirconia crowns when Gluma, Shield Force Plus, and Telio CS desensitizers were used with resin luting cement. Four groups with ten specimens each (n = 10) were considered as Group 1 (Control group, with no desensitizer application before crown cementation with resin cement) and Groups 2, 3, and 4 (with a single coat of Gluma dentin desensitizer, Telio CS desensitizer, or Shield Force Plus desensitizer applied before crown cementation, respectively). Thermocycling was then carried out, and each group was tested to determine the associated retentive forces and type of failure. The data were statistically analyzed, which showed that the mean tensile-strength values were significantly higher in Group 2 (p-value = 0.001), Group 3 (p-value = 0.027), and Group 4 (p-value = 0.014), when compared with the Control group. Clinicians should consider the application of any of these three desensitizers, as they can successfully abate dentin hypersensitivity after tooth preparation, as well as increase the durability and strength of the zirconia prosthesis.

Influence of resin cement and thermocycling on milled lithium disilicate ceramic microshear bond strength

The aim of this study was to compare the microshear bond strength of different resin cements to CAD/CAM-created lithium disilicate ceramics after 24 hours and after 1 year (10,000 thermocycles). Forty (40) ceramic bars were subjected to pretreatment comprising airborne abrasion with aluminum oxide particles, etching with 10% hydrofluoric acid and Monobond N application. Bars were divided into 4 groups (n = 10), based on cement type: light-cured Variolink Esthetic LC (VLC) and dual-cured Variolink N (VN) at two different times: after 24 hours and after 1 year. Silicone molds were used to prepare cement cylinders on a ceramic surface. The set was stored in distilled water at 37ºC, for 24 hours or subjected to 10,000 thermocycles. The molds were removed and microshear bond strength was tested. Data were submitted to two-way analysis of variance and Tukey's test (α = 0.05). Based on the comparison between cement values at different aging times (p = 0.035), VN after 24 hours (27.10 ± 0.92) and after 1 year (20.62 ± 1.25) presented significantly higher values than VLC after 24 hours (14.79 ± 0.76) and after 1 year (6.61 ± 0.81). Bond strength recorded for both cements after 24 hours (VN: 27.10 ± 0.92 and VLC: 14.79 ± 0.76) was significantly higher than the one recorded after 1 year (VN: 20.62 ± 1.25 and VLC: 6.61 ± 0.81). The thermocycling reduced the values observed for both investigated cements; bond strength was greater for dual-cure resin cement than for light-cured resin cement.

The effect of root canal rinsing protocol on the push-out bond strength to the dentin cementation of the fiber post

B a c k g r o u n d: Studies on the effect of root canal rinsing protocols on fiber post bonding to dentin are inconclusive. This study reports investigation of this topic. O b j e c t i v e s: to determine effects of irrigation protocol by means of a push-out test on the strength of adhesion between the post and dentin in an in vitro study. Materials and Method: Thirty human single-rooted teeth were prepared using hand instruments and the step-back technique, filled with gutta-percha, sealed with AH Plus (Dentsply), and divided into three groups: A: rinsed with NaCl; B: rinsed with 2% chlorhexidine (CHX); C: not rinsed before cementation of posts. The fiber posts were set using RelyX and Built-it. The tooth roots were sliced and the push-out test was performed. The area of contact between the post and dentin was calculated and the destroying force was established. The results were statistically analyzed. R e s u l t s: The mean adhesive strength was 10.69 MPa in group A, 16.33 MPa in group B, and 16.72 MPa in C. The adhesive strength in group B and C was statistically significantly higher than in group A (p = 0.0016, ANOVA). Conclusion: Rinsing root canals with CHX seems to be the most effective method prior to setting a fiber post.

Effect of Light-Sources and Thicknesses of Composite Onlays on Micro-Hardness of Luting Composites

The aim of this study was to compare three different light-curing-units (LCUs) and determine their effectiveness in the adhesive cementation of indirect composite restorations when a light-curing resin cement is used. Two resin composites were selected: Enamel Plus HRI (Micerium) and AURA (SDI). Three thicknesses (3 mm, 4 mm and 5 mm) were produced and applied as overlays and underlays for each resin composite. A standardized composite layer was placed between underlay and overlay surfaces. Light curing of the resin-based luting composites was attained through the overlay filters using LCUs for different exposure times. All specimens were allocated to experimental groups according to the overlay thickness, curing unit and curing time. Vickers Hardness (VH) notches were carried out on each specimen. Data were statistically evaluated. The curing unit, curing time and overlay thickness were significant factors capable of influencing VH values. The results showed significantly decreased VH values with increasing specimen thickness (p < 0.05). Significant differences in VH values were found amongst the LCUs for the various exposure times (p < 0.05). According to the results, a time of cure shorter than 80 s (with a conventional quartz–tungsten–halogen LCU) or shorter than 40 s (with a high-power light-emitting diode (LED) LCU) is not recommended. The only subgroup achieving clinically acceptable VH values after a short 20 s curing time included the 3 mm-thick overlays made out of the AURA composite, when the high-power LED LCU unit was used (VH 51.0). Composite thickness has an intense effect on polymerization. In clinical practice, light-cured resin cements may result in insufficient polymerization for high thickness and inadequate times. High-intensity curing lights can attain the sufficient polymerization of resin cements through overlays in a significantly shorter time than conventional halogen light.

Radiographic Study in Patients Submitted to Cementless Total Knee Arthroplasties: Minimum Follow-Up of 2 Years

Objective  Radiographic evaluate if there are signs of early loosening of the cementless total knee arthroplasties Amplitude-Score® (Amplitude Surgical SAS, Valence, France), checking with a follow-up time ranging from 2 to 5.75 years (mean of 3.75 years).

Methods  Descriptive longitudinal investigation of observational nature, non-comparative, through a static radiographic study of annual control, of a case series, in a single center, all operated on by the same surgeon (S.M.). All cementless arthroplasties that met the inclusion and exclusion criteria performed from March 2012 to October 2014 were included.

Results  Among the 46 cementless knee arthroplasties evaluated in 40 patients, no radiographic signs of early loosening were verified.

Conclusion  Cementless arthroplasty promotes optimal osteointegration, with no early release, and it is essential that the surgical technique is perfectly respected.

In Vitro Investigations in a Biomimetic Approach to Restore One-Piece Zirconia Implants

The objective of this study was to evaluate the fracture load and retention force of different bonding systems while restoring one-piece zirconia implants with a novel cementation approach using a mesostructure. Polymer-infiltrated ceramic mesostructures (n = 112) were therefore designed as caps on the implant abutment, and a molar feldspathic ceramic crown was constructed on top of it as a suprastructure. For cementation, different bonding systems were used. Fracture load and retention force were measured immediately after storage in water at 37 °C for 24 h (n = 8) as well as after artificial aging in a chewing simulator and subsequent thermal cycling (n = 8). Combined restorations showed higher fracture load compared to monolithic restorations of polymer-infiltrated ceramic (n = 8) or feldspathic ceramic (n = 8) identical in shape. However, the fracture load of the combined restorations was significantly affected by aging, independent of the primers and cements used. Restorations cemented with primers containing methyl methacrylate and 10-methacryloyloxydecyl dihydrogen phosphate exhibited the highest retention force values. Aging did not affect the retention force significantly. Similar fracture load values can be expected from combination restorations when compared with monolithic crowns.

Evolution of Small Strain Soil Stiffness during Freeze-Thaw Cycle: Transition from Capillarity to Cementation Examined Using Magnetic and Piezo Crystal Sensors

Freeze-thaw cycles caused by seasonal temperature fluctuations significantly affect the geotechnical engineering properties. This study investigated the crucial role of water distribution patterns in the characterization of elastic wave properties for the fine F-110 sand during a freeze-thaw cycle. Sand specimens with four different water distribution patterns were prepared, namely homogeneously-mixed, evaporation-driven, vertically-, and horizontally-layered specimens. The P- and S-wave signatures of the specimens were monitored using piezo crystal sensors. Results indicated the criticality of water distribution patterns in the determination of small-strain soil properties even though the specimens had identical global water saturation. The nuclear magnetic resonance-based water volume depth profiles indicated that the evaporation-driven specimens had more heterogeneous pore-invasive ice-bonding layers at a high water saturation region; by contrast, the drying process facilitated uniform meniscuses around the particle contacts near the air percolation threshold. Elastic wave measurements for laboratory-prepared specimens might over/underestimate the small-strain soil stiffness of sediments in nature, wherein the drying processes prevailed to control the water saturation. This study highlighted a clear transition from capillary-controlled to cementation-controlled elastic wave properties during temperature oscillations.

Cement pressurizing reduces radiolucent lines at glenoid: A randomized, multicentric study

BACKGROUND

The hypothesis of this study is that cement pressurization into the glenoid reduces the rate of radiolucent lines in total shoulder arthroplasty in the mean 25.5 months after the operation.

METHODS

To examine this effect, a multicentric prospective randomized study (level of evidence 1) was initiated: one group (group P, n = 24) received intraoperative pressurization of cement into the cancellous bone of the glenoid, the other cement without pressure (group NoP, n = 27). Inclusion criteria were an osteoarthritis with glenoid erosion <15° and an intact rotator cuff.

RESULTS

There were no significant differences preoperatively between the groups regarding age (mean age 66 ± 10 years (range 44-81)), gender, range of motion, scores and pathomorphology. Both groups had a significant improvement of the scores, strength, motion and satisfaction 25.5 months after the intervention. The scores were similar between the groups (ns). However, cement pressurization at the glenoid side significantly reduced the incidence of radiolucent lines (p < 0.027).

CONCLUSION

This supports the use of this simple technique to improve long-term survival of total shoulder arthroplasty.Level of evidence: 1.

Cementation of the highly cross-linked polyethylene liner into a well-fixed acetabular shell to treat patients with recurrent dislocation after total hip arthroplasty

Cementation of a highly cross-linked polyethylene liner into a well-fixed acetabular shell provided a good durability for liner wear. However, its efficacy in treating recurrent instability due to malposition cup is less reported. The aim of this study is to evaluate the outcome of this surgical technique to treat hip instability. From 2009 to 2019, we have identified 38 patients who had been surgically treated for recurrent instability, including cementation liner (N = 20) and revision cup (N = 18) procedures. Patients were followed for a mean of 45.66 months. We have recorded and analyzed all causes of implant failure including recurrent instability. Clinical outcomes were assessed including complication and Harris Hip Score (HHS) preoperatively and at the latest follow-up. Revision-free survivorship for any cause was 95.0% at 1 year, and 84.4% at 5 years in cementation liner group and 88.9% at 1 year and 5 years in revision cup group. Mean Harris hip score improved from 48.3 points preoperatively to 79.5 points at the last follow-up in cementation liner group and mean HHS improved from 43.3 points preoperatively to 77.2 points in revision cup group. There were two implant failures in each group, including one is due to persistent hip instability and the other is due to periprosthetic joint infection in the cementation liner group and two implant failure are due to persistent hip instability in the revision cup group. Functional scores and implant survival were similar in both groups. We demonstrated that orientation correction via the cementation of the polyethylene liner into well-fixed acetabular shell is a promising option to treat and prevent instability. Level of Evidence: Therapeutic Level IV.

Inhibition of root dentin demineralization by ion releasing cements

OBJECTIVES

To compare the ability of resin-modified glass ionomer (RMGI) and bioactive cements to prevent root dentin demineralization.

MATERIALS AND METHODS

Fifty molars were prepared at the cementum-enamel junction (n = 10) and restored with three bioactive cements (Activa Bioactive Cement, ACT; Ceramir Crown and Bridge, CER; and Theracem, THE), a self-adhesive resin cement (Rely X Unicem 2, UNI), and a RMGI cement (Rely X Luting Plus, LUT). Specimens were cycled for 30 days between a demineralization solution (pH = 4) composed of 0.1 M lactic acid and 3 mM Ca₃ (PO₄ )₂ for 4 hours and a remineralization solution (pH = 7.0) composed of 1.5 mM Ca, 0.9 mM P, and 20 mM Tris(hydroxymethyl)-aminomethane for 20 hours. Specimens were sectioned to 100 μm and evaluated with polarized light microscopy. A line was drawn parallel with the zone of demineralization for each tooth. The areas of "inhibition" (external to the line) were measured as positive values and "wall lesions" (pulpal to the line) were measured as negative areas.

RESULTS

Significant differences were found between materials for "inhibition/wall lesion" areas in root dentin (P < .001) and ranked as (μm² , mean ± SD): LUT (7700 ± 2500) > CER (3800 ± 1900), THE (2100 ± 2600), and ACT (1400 ± 700) > UNI (-2000 ± 1700).

CONCLUSIONS

Bioactive cements showed net areas of demineralization inhibition albeit at a lower level than a reference RMGI cement.

CLINICAL SIGNIFICANCE

RMGI or bioactive cements may be indicated for patients at risk of secondary caries around crown margins.

A potential need for surgeon consensus: Cementation techniques for total knee arthroplasty in orthopedic implant manufacturers' guidelines lack consistency

AIM

Given recent concerns regarding the influence of different cements and implants on the rate of aseptic failures in total knee arthroplasty (TKA), we wondered if cementation technique could play a role. The primary aim of this review was to collect and compare the surgeon education materials from eight orthopedic implant manufacturers to evaluate the manufacturers' recommended cementation technique in TKA and identify if there was any consistency in these readily available guides as to the best practices of cementation of their implants.

MATERIALS AND METHODS

We reviewed contemporary surgeon education guidelines for all TKA systems available from eight manufacturers. Variables included: cement type, batches prepared, surface preparation prior to application, cleaning and/or drying the bone surface, mixing the cement, the waiting phase after the cement has been mixed prior to application, pressurizing the cement, location of cement application, and the curing time. Data were recorded and organized for qualitative comparisons.

RESULTS

We identified a total of 43 guides covering 38 implants from eight different manufacturers. There were 41 surgical technique guides and two general brochures regarding cementation techniques available from the manufacturers. Even within the manufacturers' own guidelines for the different implants, there was a wide variety of differing guidelines on many aspects of the cementation technique.

CONCLUSION

There is clearly no consensus for a preferred cementation technique both within and among manufacturers' surgeon education materials regarding tibial baseplate cementation during TKA. Efforts may be needed to identify a best-practice cementation technique in an effort to reduce the number of TKA failures associated with aseptic loosening.

Influence of luting cement on the clinical outcomes of Zirconia pediatric crowns: A 3-year split-mouth randomized controlled trial

BACKGROUND

There is no scientific evidence supporting the choice of luting cement for cementation of zirconia crowns.

AIM

The purpose of this split-mouth study was to compare the efficacy of using bioactive cement versus packable glass ionomer for cementation of posterior pediatric zirconia crowns.

DESIGN

Fifty first mandibular primary molars were restored by zirconia crowns and were randomly divided to be luted with either (a) bioactive cement or (b) packable glass ionomer. Crowns' retention, fracture, and gingival condition were evaluated at 1 week, and 1-, 3-, 6-, 9-, 12-, 18-, 24-, and 36-month intervals. Statistical analysis was carried out using Fisher's exact test, Kaplan-Meier survival analysis, and Wilcoxon signed rank test.

RESULTS

At 3- to 36-month follow-ups, there were statistically significant (P = .009-≤.001) less debonded crowns in packable glass ionomer group. There were no fractured crowns for either cements. There was no statistically significant difference between gingival index scores.

CONCLUSIONS

Packable glass ionomer is more retentive than bioactive cement when used for cementing zirconia pediatric crowns. Posterior zirconia pediatric crowns have high fracture resistance after 36 months of clinical performance, irrespective of luting cement. Luting cement for zirconia pediatric crowns has no apparent effect on gingival condition around crowns.

Fracture Resistance of Zirconia-Reinforced Lithium Silicate Ceramic Crowns Cemented with Conventional or Adhesive Systems: An In Vitro Study

In recent years, Zirconia-reinforced Lithium Silicate ceramic (ZLS), combining lithium-silicate and zirconia features, has shown to have excellent mechanical and aesthetic characteristics. Thus, the aim of this study was to compare the fracture strength of ZLS single crowns cemented with two different cementation techniques. Twenty crowns were realised and cemented on teeth replicas achieved from an extracted premolar human tooth. The samples were divided into two groups of 10 specimens each, Glass-ionomeric cement (GIC) group and Self-Adhesive Resin Cement (ARC) group. The mechanical test was performed using a universal testing machine. The specimens were then evaluated with a scanning electron microscope (SEM) to identify for all crowns and related abutments the pattern of fracture after the breaking point. The data obtained were statistically analysed. The mean fracture toughness values and standard deviations (±SD) were 2227 ± 382 N and 3712 ± 319 N respectively for GIC and ARC groups. In fact, t-test showed a statistically significant difference between the two groups (p < 0.001). Moreover, the SEM results demonstrated portions of abutments still attached to the crown fragments in the ARC group, whilst these were not present in the GIC group. Within the limitations of this study, these results suggest the use of adhesive cementation for ZLS crowns, which significantly increase the compressive strength of ZLS restorations compared to GIC.

Fatigue Failure Load of Resin-bonded Simplified Lithium Disilicate Glass-Ceramic Restorations: Effect of Ceramic Conditioning Methods

PURPOSE

To evaluate the influence of different ceramic surface conditioning methods on the fatigue failure load of adhesively cemented simplified lithium-disilicate glass-ceramic restorations.

MATERIALS AND METHODS

Ceramic (IPS e.max CAD, Ivoclar Vivadent) (Ø = 10 mm; thickness = 1.2 mm) and epoxy resin (Ø = 10 mm; thickness = 2.3 mm) disks were produced. The ceramic bonding surfaces were treated as follows: no etching and MPS-silane primer application only (MN); etching with 10% hydrofluoric acid (HF) for 20 s followed by primer application (HF + MN); HF + universal multimode adhesive application (HF + SU); etching with a one-step etching primer (ME&P); HF + primer + conventional adhesive (HF + MN + PAB). The epoxy resin disks were etched with 10% HF for 20 s followed by a coat of bonding agent (Multilink Primer A+B). Pairs of ceramic/epoxy resin disks were cemented with composite cement (Multilink N, Ivoclar Vivadent). The mean fatigue failure load was determined by the staircase method (100,000 cycles at 20 Hz frequency; initial load = 1435 N; step size = 72 N).

RESULTS

ME&P had the highest fatigue failure load, followed by HF etched groups, while the non-etched condition (MN group) had the lowest. All samples presented radial cracks originating from defects at the conditioned ceramic surface (interface).

CONCLUSION

The simultaneous physicochemical conditioning with one-step self-etching ceramic primer promoted the best fatigue behavior results of the glass-ceramic restorations. It might indicate that this one-step conditioning reduces the number of flaws at the ceramic surface due to the slighter surface alterations than those produced by hydrofluoric acid etching, improving the fatigue behavior.

Adhesive Systems Used in Indirect Restorations Cementation: Review of the Literature

New technologies are changing the therapeutical options to do indirect restorations and new adhesive systems are continuously introduced to be used by clinicians. Different interactions between restorations, adhesive systems components, enamel and dentin require having criteria based on the selection of the adhesive system, ensuring the longevity of the restorations and the preservation of the biological remnant. The adhesion force to the dental tissue is one of the indicatives of the behavior of the adhesive systems and influences the behavior of the treatments with direct and indirect restorations. The objective of this search was to find the adhesive systems with the best results in terms of the adhesion strength of indirect restorations on the dental tissues. The search was conducted in two MEDLINE digital databases (PubMed), and the Cochrane Library with a search strategy based on the combination of MeSH (Medical Subject Headings) keywords. This systematic review used the PRISMA guide (Preferred Reporting Items for Systematic Reviews and Meta-Analysis). According to this review, the 3-step adhesive systems were the best performing and still are the gold standard for the cementing of indirect restorations. In addition, it can be concluded that self-etched adhesive systems reduce the time spent in clinical practice, however at the interface level they behave as permeable membranes more susceptible to degradation.

Tin and silver recovery from wave soldering dross

This work proposes a method for the recovery of tin and silver from wave soldering dross produced during the manufacture of printed circuit boards. Samples of wave soldering dross were first subjected to carbothermic reduction to obtain an ingot containing the above metals plus other elements. This ingot was then subjected to electrorefining at different densities of electrical current, electrolyte flow rate, and cathode-anode separation distance, to determine the optimum conditions for recovering pure tin. Under such conditions, 82 wt% of the tin in the ingot was recovered at a purity of 99.94%. After subjecting ingots to continuous electrorefining under optimum conditions for 845 h, the slime collected at the anode was removed for the recovery of silver. This slime was subjected to thin-layer leaching with concentrated nitric acid. The leachate produced was subjected to copper-cementation; the silver adhering to the copper rod was collected by washing. This process recovered 92% of the silver in the wave soldering dross ingot at a purity of >99.6%. Some 99% of the copper entering the leachate from the copper rod during cementation was recovered by liquid-liquid extraction with 40% LIX84 (dissolved in EXXOL D100). This method could provide a rapid, inexpensive means of recovering pure tin and silver from wave soldering dross.

Evaluation of marginal leakage after mechanical fatigue cycling of composite inlays luted with different cements

This in vitro study evaluated the marginal microleakage of composite inlays luted with 3 different cement systems. The null hypothesis was that the luting materials would not influence dye penetration, showing the same degree of microleakage. Thirty-six sound molars were selected, mesio-occlusodistal cavities were prepared, and the teeth were randomly divided into 3 groups (n = 12). Composite resin inlay restorations were made and cemented using a dual-curing resin cement (Calibra), a light-curing flowable composite (Charisma Flow), or a self-adhesive resin cement (RelyX Unicem). The restored teeth were subjected to fatigue cycles and immersed in 0.5% basic fuchsin dye for 24 hours. Two orthogonal cuts were made to enable evaluation of dye penetration at the cervical and occlusal margins. The sections were evaluated with a 4-point scale ranging from 0 (no penetration) to 3 (penetration up to the cavity floor [occlusal margins] or axial wall [cervical margins]). The Calibra and Charisma Flow groups showed greater microleakage, notably at the cervical margins, whereas RelyX Unicem specimens showed the least dye penetration. Significant differences were found between the Calibra and Charisma Flow groups and between the Charisma Flow and RelyX Unicem groups (P < 0.05). No statistically significant differences were detected between the Calibra and RelyX Unicem groups. The microleakage associated with the flowable composite was significantly greater than that associated with both resin cements, results that discourage its use for luting of Class II composite inlays.

Fracture strength of CAD/CAM posterior ceramic crowns after manual enhancement of occlusal morphology

PURPOSE

The aim of this study was to investigate the fracture strength of computer-aided design/computer-aided manufacturing (CAD/CAM) posterior ceramic crowns with and without post-milling manual enhancement of occlusal morphology (MEOM), as indicated especially with early CAD/CAM restorations that have limited capacity to generate natural occlusal morphology.

MATERIALS AND METHODS

A mandibular molar of an acrylic tooth model was prepared to receive a CAD/CAM all-ceramic crown and was used as a master die to fabricate 80 prepared tooth replicas using an epoxy resin with an elastic modulus (E) of 18 GPa. The crown was designed using Cerec software's Biogeneric Copy Design mode (Sirona). Eighty identical monolithic crowns were fabricated by milling four types of ceramic blocks. Forty monolithic crowns (10 of each ceramic system) were randomly selected as the control group, and MEOM was performed for each of the other 40 crowns by a certified dental technician. Restorations were crystallized and glazed according to the manufacturers' instructions and firing protocols. All crowns were cemented to their respective die using resin cement, and loaded to fracture at a crosshead speed of 0.5 mm/min. The resultant fractures were classified into three modes. Data were statistically analyzed using the nonparametric Mann-Whitney U test at α = 0.05.

RESULTS

The MEOM treatment decreased the fracture load for all ceramic brands.

CONCLUSION

The MEOM procedure should be considered detrimental for monolithic CAD/CAM-generated crowns and should thus be avoided.

Qualitative evaluation of the adesive interface between lithium disilicate, luting composite and natural tooth

Aim of this work was to qualitatively evaluate the interface between tooth, luting composite and lithium disilicate surface using a scanning electron microscope (SEM). An extracted restoration-free human molar was stored in physiological solution until it was embedded in an autopolimerysing acrylic resin. A standard preparation for overlay was completed and after preparation an anatomic overlay was waxed on the tooth and then hot pressed using lithium disilicate ceramic. After cementation the sample was dissected and the section was analysed using an Automatic Micromet (Remet s.a.s) and the section was analyzed using a scanning electron microscope (SEM). SEM evaluation of the tooth showed the three layers seamlessly; by increasing the enlargement the interface did not change.

A geological perspective on the degradation and conservation of western Atlantic coral reefs

Continuing coral-reef degradation in the western Atlantic is resulting in loss of ecological and geologic functions of reefs. With the goal of assisting resource managers and stewards of reefs in setting and measuring progress toward realistic goals for coral-reef conservation and restoration, we examined reef degradation in this region from a geological perspective. The importance of ecosystem services provided by coral reefs-as breakwaters that dissipate wave energy and protect shorelines and as providers of habitat for innumerable species-cannot be overstated. However, the few coral species responsible for reef building in the western Atlantic during the last approximately 1.5 million years are not thriving in the 21st century. These species are highly sensitive to abrupt temperature extremes, prone to disease infection, and have low sexual reproductive potential. Their vulnerability and the low functional redundancy of branching corals have led to the low resilience of western Atlantic reef ecosystems. The decrease in live coral cover over the last 50 years highlights the need for study of relict (senescent) reefs, which, from the perspective of coastline protection and habitat structure, may be just as important to conserve as the living coral veneer. Research is needed to characterize the geological processes of bioerosion, reef cementation, and sediment transport as they relate to modern-day changes in reef elevation. For example, although parrotfish remove nuisance macroalgae, possibly promoting coral recruitment, they will not save Atlantic reefs from geological degradation. In fact, these fish are quickly nibbling away significant quantities of Holocene reef framework. The question of how different biota covering dead reefs affect framework resistance to biological and physical erosion needs to be addressed. Monitoring and managing reefs with respect to physical resilience, in addition to ecological resilience, could optimize the expenditure of resources in conserving Atlantic reefs and the services they provide.

Quality of cementation in conventional versus minimally invasive total knee arthroplasty

PURPOSE

To review the immediate postoperative radiographs of 108 patients following conventional or minimally invasive total knee arthroplasty (TKA) to assess the quality of cementation in terms of cement voids and retained cement.

METHODS

Records of 20 male and 88 female consecutive patients aged 50 to 83 (mean, 67.5) years who underwent conventional TKA (n=56) or computer-assisted minimally invasive TKA (n=52) for osteoarthritis by a single senior surgeon were reviewed. Immediate postoperative radiographs were assessed by a single blinded assessor for the quality of cementation in terms of cement void and retained cement in different zones of the femoral, tibial, and patellar components along the prosthesis-bone interface using the Knee Society total knee arthroplasty roentgenographic evaluation and scoring system.

RESULTS

The 2 groups were comparable in terms of baseline demographics as well as cement void and retained cement on the femoral, tibial, and patellar components, except that in the minimally invasive group, cement void beneath the anterior flange of the femoral component was wider (0.32 vs. 0 mm, p=0.001), and retained cement in the posterior or lateral aspects of the tibial component was more common (50.0% vs. 28.6%, p=0.018).

CONCLUSION

Minimally invasive TKA resulted in a wider cement void beneath the anterior flange of the femoral component and a higher rate of retained cement around the tibial component.

Retention Strength of PMMA/UDMA-Based Crowns Bonded to Dentin: Impact of Different Coupling Agents for Pretreatment

Computer aided design/computer aided manufacturing (CAD/CAM) polymers for long-term dental restorations benefit from enhanced mechanical properties. However, the quantification of their bonding properties on teeth is lacking. Therefore, the aim of this study was to determine the retention strength (RS) of differently pretreated new developed polymethylmethacrylate/urethanedimethacrylate-based CAD/CAM polymer bonded on dentin. In summary, 120 human caries-free molars were prepared, and polymeric crowns were milled and pretreated (n = 20): visio.link (VL), Scotchbond Universal (SU), Monobond Plus/Heliobond (MH), Margin Bond (MB), Margin Bond mixed with acetone (1:1) (MBA) or not pretreated (CG). Half of the specimens were cemented using Variolink II and the other half with RelyX Ultimate. Specimens were stored for 24 h in distilled water and thermal cycled (5000 ×, 5 °C/55 °C). The retention load was measured and failure types were defined. RS was calculated and analyzed using both two- and one-way ANOVA with a post-hoc Scheffé-test, unpaired t-test, Kaplan–Meier with Breslow–Gehan test and chi-squared test (p < 0.05). Crowns bonded using RelyX Ultimate showed higher RS than those bonded using Variolink II. The pretreatment showed no impact on the RS. However, survival analysis within Variolink II found an impact of pretreatment. The median RS for MH was the lowest and statistically different from MB, MBA and CG. For Variolink II MH had the poorest survival as the estimated cumulative failure function of the debonded crown increased very quickly with increasing TBS. Within the RelyX Ultimate groups, no significant differences were determined. The newly developed CAD/CAM polymer showed the highest bonding properties after cementation using RelyX Ultimate.

Long Term Results of Liner Polyethylene Cementation Technique in Revision for Peri-acetabular Osteolysis

Patients with peri-acetabular osteolysis around a well fixed cementless acetabular component may be treated with liner exchange. When the locking mechanism is unreliable or unavailable, cementing the liner into the fixed acetabular component is a feasible option. The purpose of this study was to evaluate the clinical and radiographic long term results of this technique. Forty hip revisions with liner cementation in 37 patients were performed. The minimum follow up was 10 years. Modified Harris Hip Score and recent x rays were reviewed. Four hips were re-revised. Two patients were diagnosed with exacerbation of osteolysis but refused revision. Dislocation rate was relatively high (16%). Liner cementation technique in revision hip surgery is useful in patients with a well fixed metal backed acetabular component.

The effect of viscosity on cement penetration in total knee arthroplasty, an application of the squeeze film effect

The authors present a prospective randomized blinded cadaver study designed to evaluate the engineering concept of a squeeze film effect and the effect of cement viscosity on cement penetration in total knee arthroplasty. This was done in response to an earlier clinical study demonstrating inferior tibial cement penetration using early, often liquid, phase cement. Paired cadaver tibias were implanted with the tibial component using either liquid or dough phase cement. Based on an AP fluoroscopic image, the dough phase cement penetrated deeper than liquid in all four zones. This was statistically significant in zones 1, 2 and 3. Deeper cement penetration has been shown to provide a stronger cement-bone interphase. As a result dough phase cement is recommended to obtain optimal cement penetration.

The distribution of implant fixation for femoral components of TKA: a postmortem retrieval study

Aseptic loosening of total knee arthroplasty (TKA) components is the foremost cause of implant failure in the long term. While tibial component loosening is of primary concern, femoral loosening may become a clinical problem due to younger, more active patients seeking TKA, and also high-flexion designs. In this study, we analyzed the fixation for 19 non-revised, postmortem retrieved, femoral components of TKA with time in service ranging from 1 to 22 years. We found that the average total contact fraction for cemented components was 9.5% and had a power law response (decrease) with years in service. The average initial interdigitation depth was 0.7mm, and the average current interdigitation depth was 0.13mm. Loss of interdigitation was 81%. Over all, minimal fixation seems necessary for long-term success of TKA femoral components.

Tumor endoprosthesis revision rates increase with peri-operative chemotherapy but are reduced with the use of cemented implant fixation

Chemotherapy may reduce osseointegration of tumor endoprosthesis, while delaying chemotherapy may reduce survival. We studied the effects of chemotherapy and cemented fixation on tumor endoprosthesis survivorship with a retrospective analysis of 50 consecutive patients receiving lower limb salvage surgery. We compared rates of radiographic loosening/revision and effect of cement fixation between chemotherapy/no chemotherapy cohorts. Chemotherapy increased the total revision rate (HR = 3.8 [1-14], P = 0.033), but did not affect aseptic loosening. Cement fixation reduced revision for loosening (HR = 0.09 (0.008-0.98), P = 0.012) and showed less radiographic loosening (HR = 0.09 (0.02-0.51), P = 0.00066). Cement fixation had lower rates of revision for loosening and radiographic loosening regardless of whether chemotherapy was given. We conclude that for these implants, cement fixation provides superior results to uncemented fixation.

Effects of Ground Conditions on Microbial Cementation in Soils

The purpose of this study is to understand the effect of ground conditions on microbial cementation in cohesionless soils. Since the method of microbial cementation is still at the experimental stage, for its practical use in the field, a number of laboratory experiments are required for the quantification of microbial cementation under various ground conditions, such as relative densities, relative compactions and particle size distributions. In this study, in order to evaluate the effectiveness of microbial cementation in treated sands and silts, an experiment was performed for different relative densities of silica sands, for different relative compactions of silts and for different particle size distributions of weathered soils sampled from the field. Scanning electron microscope (SEM), X-ray diffraction (XRD), energy dispersive X-ray (EDX) spectroscopy and mapping analyses were implemented for the quantification of the levels of microbial cementations for sand, silt and weathered soil specimens. Based on the test results, a considerable microbial cementation was estimated depending on the soil conditions; therefore, an implementation of this new type of bio-grouting on a weak foundation may be possible to increase the strength and stiffness of weak ground.