Restauração em resina composta semidireta em dente posterior: relato de caso / Semi-direct composite restoration in posterior toth: a case report

A escolha da técnica restauradora desempenha papel fundamental na eficácia e duração de um tratamento reabilitador. O objetivo deste relato de caso foi descrever a utilização da técnica semidireta para a confecção de uma restauração em resina composta em um primeiro molar inferior. A paciente apresentava uma restauração insatisfatória no dente 36, que necessitava ser substituída devido à infiltração por cárie. Optou-se pela técnica semidireta devido à amplitude da cavidade, que envolvia estruturas de suporte, e pela combinação das vantagens das abordagens direta e indireta. O procedimento envolveu a remoção de tecido cariado, a aplicação de hidróxido de cálcio pasta, seguida da aplicação de uma fina camada de ionômero de vidro e, posteriormente, resina fluída para realizar o selamento dentinário. O preparo foi realizado seguindo os princípios necessários. O elemento em questão foi moldado com silicone de adição e o arco antagonista, com alginato. Ambos modelos foram vertidos com silicone para modelos semirrígidos e montados em oclusor de peças de brinquedo. A restauração semidireta foi confeccionada em resina composta Filtek Z350 XT, respeitando a anatomia do dente 36. Pigmentos foram utilizados para aprimorar detalhes estéticos. Após acabamento e polimento, a peça foi condicionada e cimentada com cimento dual Relyx Ultimate. Pode-se concluir que a abordagem restauradora por meio da técnica semidireta construída em modelo semirrígido é uma opção terapêutica conservadora e vantajosa para dentes com extensa destruição coronária. Essa técnica possibilita a restauração de forma eficaz, garantindo tanto a estética quanto a função adequada do dente afetado(AU)

The choice of restorative technique plays a fundamental role in the effectiveness and duration of rehabilitation treatment. The objective of this case report was to describe the use of the semi-direct technique to create a composite resin restoration in a lower first molar. The patient had an unsatisfactory restoration on tooth 36, which needed to be replaced due to cavity infiltration. The semi-direct technique was chosen due to the amplitude of the cavity, which involved support structures, and the combination of advantages of the direct and indirect approaches. The procedure involved the removal of carious tissue, and the application of calcium hydroxide paste, followed by the application of a thin layer of glass ionomer and, subsequently, fluid resin to seal the dentin. The preparation was carried out following the necessary principles. The element in question was molded with addition silicone and the antagonist arch was molded with alginate. Both models were poured with silicone for semi-rigid models and mounted on toy parts occluders. The semi-direct restoration was made in Filtek Z350 XT composite resin, respecting the anatomy of tooth 36. Pigments were used to improve aesthetic details. After finishing and polishing, the piece was conditioned and cemented with Relyx Ultimate dual cement. It can be concluded that the restorative approach using the semi-direct technique built on a semi-rigid model is a conservative and advantageous therapeutic option for teeth with extensive coronal destruction. This technique allows for effective restoration, ensuring both the aesthetics and adequate function of the affected tooth(AU)

Transfer of Guided Emergence Profile Developed Using Customized Provisional Implant Restoration and Cementation Using an Abutment Replica Technique: A Case Report.

The long-term success of dental implants depends not only upon implant osseointegration, but also on the surrounding soft tissue health and profile. An ideal emergence profile contributes to the aesthetics of an implant restoration. It maintains long-term implant health by preventing potential food accumulation and forming a barrier against bacterial ingress. This article describes a method for obtaining an impression of implants that will capture the custom guided peri-implant soft tissue contours accurately, thus contributing to a final restoration with favorable aesthetics. We also describe a technique for reducing excess cement in a cement retained implant crown, thereby contributing to the health of the peri-implant tissues.

Evidence-based clinical management of localised tooth wear and a repeatedly dislodged posterior crown utilising the Dahl Concept.

This clinical case report demonstrates the use of the Dahl Concept in the management of the repeated dislodgement of a posterior full coverage crown associated with a reduced restorative space. The described technique harnesses the addition of resin composite and a temporarily cemented provisional full coverage crown to create sufficient restorative space for the cementation of a definitive posterior full coverage crown restoration at the six-month review.

Intra-radicular retention with custom designed CAD-CAM fibRe-reinforced composite post-core: a dental technique.

A technique is outlined for utilising a polymeric composite reinforced with glass fibres in a three-dimensional mesh as a post-core in aesthetic cases. The clinical procedure involves obtaining an impression of the root canal space, scanning the definitive cast, and milling a fibre-reinforced composite post-core. Subsequently, the intra-radicular post-core is cemented using an adhesive resin cement. The use of custom-made computer-aided design-computer-aided manufacturing (CAD-CAM) fibre-reinforced composite post-core facilitates repairability, provides better adaptation to the root canal space, avoids uneven cement thickness, ensures chemical adhesion to resin cement, and promotes favourable aesthetics when combined with all-ceramic crowns.

The effect of restorative material selection and cementation procedures on the durability of endocrowns in the anterior teeth: an in-vitro study.

OBJECTIVE: To investigate the fracture resistance and failure modalities of anterior endocrown restorations fabricated employing diverse ceramic materials, and bonded using various cementation methodologies. MATERIALS AND METHODS: Forty maxillary central incisors were divided into two main groups based on the ceramic materials used; GroupI (Zir): zirconia endocrwons (Zolid HT+, Ceramill, Amanngirrbach) and GroupII (E-Max): e-max endocrowns (IPS e.max CAD, Ivoclar Vivadent). Both groups were further split into two subgroups depending on the cementation protocols; subgroup IA "ZirMDP": endocowns cemented with MDP primer + MDP resin cement, subgroup IB (ZirNon-MDP): cemented with MDP primer + non-MDP resin cement, subgroup IIA (E-maxMDP): cemented with MDP primer + MDP resin cement, subgroup IIB (E-maxNon-MDP): cemented with MDP primer + non-MDP resin cement. (n = 10/subgroup). Endocrowns were manufactured using CAD/ CAM. Teeth were subjected to 10,000 thermal cycles. The fracture test was performed at 45o with a palatal force direction until the fracture occurred. Test results were recorded in Newton. The failure mode was examined using a stereomicroscope. A One-way ANOVA test was utilized to compare different groups regarding fracture strength values. Tukey`s Post Hoc was utilized for multiple comparisons. RESULTS: The comparative analysis of fracture strength across the diverse groups yielded non-significant differences, as indicated by a p-value exceeding 0.05. Nonetheless, an observable trend emerged regarding the mode of failure. Specifically, a statistically significant prevalence was noted in fractures localized within the endocrown/tooth complex below the cementoenamel junction (CEJ) across all groups, except for Group IIB, "E-max Non-MDP," where fractures within the endocrown/tooth complex occurred above the CEJ. CONCLUSIONS: Combining an MDP-based primer with an MDP-based resin cement did not result in a significant effect on the anterior endocrown fracture strength. CLINICAL RELEVANCE: Regardless of the presence of the MDP monomer in its composition, adhesive resin cement achieved highly successful fracture strength when used with MDP-based ceramic primers. Additionally, ceramic materials exhibiting elastic moduli surpassing those of dentin are discouraged due to their propensity to induce catastrophic fractures within the tooth structure.

A conservative approach to localize loose implant screw through cemented crown: an in vitro experimental study.

BACKGROUND: Retrieval of cement-retained implant-supported restorations is intriguing in cases of screw loosening. Detecting the estimated size of the screw access hole (SAH) could decrease destruction to the prosthesis and preserve the crown. OBJECTIVES: To precisely localize loose implant screws through cemented crowns to reduce crown damage after screw loosening. MATERIALS AND METHODS: In this in vitro study, 60 cement-retained implants supported 30 zirconia-based, and 30 ceramics fused to metal (CFM) lower molar crowns were invented, and each was subdivided into three subgroups (10 each). In group I (AI/BI) (control), SAH was created with the aid of orthopantomography (OPG). In contrast, in group II (zirconia-crown), SAH was created with the aid of CBCT + 3D printed surgical guide with a 2 mm metal sleeve in subgroups IIA/IIIA and CBCT + MAR was used to develop SAH in subgroups IIB/IIIB. SEM and Micro-CT scanned the SAH openings to determine the diameter of the hole, cracking, chipping, and chipping volume. RESULTS: Regarding the effect of plane CBCT and CBCT + MAR on prepared crowns, a highly significant association between group I with group II (p = 0.001) and group III (p = 0.002) was detected. Regarding the cracking of SAH, significant differences between the zirconium crown and CFM restoration (p = 0.009) were found, while for the chipping, no significant association was seen between groups (p = 0.19). CONCLUSIONS: CBCT, either as a plane CBCT or with MAR, significantly improved the accuracy of drilling the screw channel and decreased injury to the existing restoration and abutment, aiding in better localization of SAH in loosened implant abutment screws.

Study on triaxial compression performance and damage characteristics of fiber-reinforced ecological matrix cementing gangue gypsum fill material.

Polypropylene fiber was equally mixed into alkali-activated slag fly ash geopolymer in order to ensure the filling effect of mine goaf and improve the stability of cemented gangue paste filling material with ecological matrix. Triaxial compression tests were then conducted under various conditions. The mechanical properties and damage characteristics of composite paste filling materials are studied, and the damage evolution model of paste filling materials under triaxial compression is established, based on the deviatoric stress-strain curve generated by the progressive failure behavior of samples. Internal physical and chemical mechanisms of the evolution of structure and characteristics are elucidated and comprehended via the use of SEM-EDS and XRD micro-techniques. The results show that the fiber can effectively improve the ultimate strength and the corresponding effective stress strength index of the sample within the scope of the experimental study. The best strengthening effect is achieved when the amount of NaOH is 3% of the mass of the solid material, the amount of fiber is 5‰ of the mass of the solid material, and the length of the fiber is about 12 mm. The action mode of the fiber in the sample is mainly divided into single-grip anchoring and three-dimensional mesh traction. As the crack initiates and develops, connection occurs in the matrix, where the fiber has an obvious interference and retardation effect on the crack propagation, thereby transforming the brittle failure into a ductile failure and consequently improving the fracture properties of the ecological cementitious coal gangue matrix. The theoretical damage evolution model of a segmented filling body is constructed by taking the initial compaction stage end point as the critical point, and the curve of the damage evolution model of the specimen under different conditions is obtained. The theoretical model is verified by the results from the triaxial compression test. We concluded that the experimental curve is in good agreement with the theoretical curve. Therefore, the established theoretical model has a certain reference value for the analysis and evaluation of the mechanical properties of paste filling materials. The research results can improve the utilization rate of solid waste resources.

Effect of cement spacer on fit accuracy and fracture strength of 3-unit and 4-unit zirconia frameworks.

BACKGROUND: Cement spacer is essential for compensating deformation of zirconia restoration after sintering shrinkage, allowing proper seating and better fracture resistance of the restoration. Studies assessing the effect of cement spacer on fit accuracy and fracture strength of zirconia frameworks are missing in the literature. Therefore, the aim of this study was to evaluate the effect of different cement spacer settings on fit accuracy and fracture strength of 3-unit and 4-unit zirconia frameworks. METHODS: Sixty standardized stainless-steel master dies were manufactured with 2 prepared abutments for fabricating 3-unit and 4-unit zirconia frameworks. The frameworks were assigned into 6 groups (n = 10) according to cement spacer setting (30 µm, 50 µm, and 80 µm) as follows: 3-unit frameworks; 3u-30, 3u-50, 3u-80, and 4-unit frameworks; 4u-30, 4u-50, and 4u-80. The frameworks were assessed for fit accuracy with the replica method. The specimens were cemented to their corresponding dies, and the fracture strength was measured in a universal testing machine. The Weibull parameters were calculated for the study groups and fractured specimens were inspected for failure mode. Two-Way ANOVA followed by Tukey test for pairwise comparison between study groups (α = 0.05). RESULTS: The cement spacer had a significant effect on both fit accuracy and fracture strength for 3-unit and 4-unit frameworks. The 50 µm spacer had significantly better fit accuracy followed by 80 µm, and 30 µm spacers. Both 50 µm and 80 µm spacers had similar fracture strength, and both had significantly better strength than 30 µm spacer. CONCLUSIONS: For both 3-unit and 4-unit zirconia frameworks, 50 µm cement spacer can be recommended over 30 µm and 80 µm spacers for significantly better fit accuracy and adequate fracture strength.

Do strength of zirconia-abutment-interfaces depend on cement, zirconia type and titanium abutment dimensions?

OBJECTIVES: Part 1 of this study investigates the influence of zirconia types, chimney heights, and gingival heights on the strength of the zirconia-abutment-interface. Part 2 extends the analysis to include adhesive brands and macro-retentions. METHODS: In Part 1, the study utilized three zirconia types (700 MPa, 1000 MPa, 1200 MPa) to fabricate 234 screw-retained zirconia crowns with varying chimney heights (3.5 mm, 4.1 mm, 5 mm) and gingival heights (0.65 mm, 1.2 mm, 3 mm) of the titanium abutments. All adherend surfaces underwent sandblasting with aluminum oxide before cementation with a specific resin cement. In Part 2, the investigation of 240 screw-retained zirconia crowns focused on a single zirconia type (1000 MPa) with chimney heights of 3.5 mm and 5 mm and a gingival height of 0.65 mm of the titanium abutments, cemented with three different resin cements. All adherent surfaces underwent sandblasting with aluminum oxide before cementation, whereas 120 out of 240 abutments received additional macro retentions. Storage in water at 37 °C for 24 h preceded the tensile test. RESULTS: The study revealed a substantial impact of chimney height and zirconia type on the bond strength of the zirconia-abutment-interface. Neither adhesive brands nor macro retentions significantly impacted the bond strength. Fracture incidence was significantly influenced by gingival height and zirconia type in part 1, whereas in part 2 smaller chimney heights correlated with a higher fracture incidence. SIGNIFICANCE: This study contributes insights into the complex interplay of factors influencing the zirconia-abutment-interface. The results provide a foundation for refining clinical approaches, emphasizing the importance of chimney height and zirconia type in achieving successful anterior gap implant restorations.

Adhesive Cementation of CAD/CAM Silica-based Ceramics: Effect of Adhesive Type and Long-term Aging on the Bond Strength to Composite Cement.

PURPOSE: To investigate the effect of adhesive type and long-term aging on the shear bond strength (SBS) between silica-based ceramics and composite cement (CC). MATERIALS AND METHODS: Lithium-silicate (LS), feldspathic (FD) and polymer-infiltrated ceramic (PIC) blocks were sectioned (10 x 12 x 2 mm) and divided into 24 groups considering the factors: "ceramics" (LS, FD, and PIC), "adhesive" (Ctrl: without adhesive; 2SC: 2-step conventional; 3SC: 3-step conventional; 1SU: 1-step universal), and "aging" (non-aged or aged [A]). After the surface treatments, CC cylinders (n = 15, Ø = 2 mm; height = 2 mm) were made and half of the samples were subjected to thermocycling (10,000) and stored in water at 37°C for 18 months. The samples were submitted to SBS testing (100 kgf, 1 mm/min) and failure analysis. Extra samples were prepared for microscopic analysis of the adhesive interface. SBS (MPa) data was analyzed by 3-way ANOVA and Tukey's test (5%). Weibull analysis was performed on the SBS data. RESULTS: All factors and interactions were significant for SBS (p<0.05). Before aging, there was no significant difference between the tested groups and the respective control groups. After aging, the LS_1SU (22.18 ± 7.74) and LS_2SC (17.32 ± 5.86) groups exhibited significantly lower SBS than did the LS_Ctrl (30.30 ± 6.11). Only the LS_1SU group showed a significant decrease in SBS after aging vs without aging. The LS_1SU (12.20) group showed the highest Weibull modulus, which was significantly higher than LS_2SC_A (2.82) and LS_1SU_A (3.15) groups. CONCLUSION: No type of adhesive applied after silane benefitted the long-term adhesion of silica-based ceramics to CC in comparison to the groups without adhesive.

The use of uncemented stems in femoral neck fractures in elderly patients: A comparative study of 671 cases.

INTRODUCTION: The use of cemented stems in elderly patients is associated with the risk of intraoperative embolic complications. Uncemented stems eliminate this risk, but their use is controversial because of the risk of mechanical complications, with estimated subsidence between 3.6 and 30% and periprosthetic fractures between 2.1 and 11% at 6 weeks. A retrospective multicenter comparative study was conducted using a propensity score analysis to evaluate mechanical performances of uncemented stems in femoral neck fractures in elderly patients to (1) compare the risk of mechanical complications and (2) assess the use of metaphyseal-anchored stems for this indication. HYPOTHESIS: There is no difference in the risk of mechanical complications, intraoperatively or postoperatively, between these stems. MATERIALS AND METHODS: We conducted a multicenter retrospective comparative study including 358 uncemented and 313 cemented stems. The mean age was 84.5 years [83.9-85.1]. The inclusion criteria were patients 70 years and older and a follow-up of at least 6 weeks. The primary endpoint was a composite endpoint comprised of stem subsidence≥2mm or periprosthetic fracture (up to 3 months postoperatively). The secondary endpoints were infection, stem subsidence≥2mm, and operative time. These endpoints were analyzed using a propensity score to control confounding factors. A secondary analysis used the same endpoints to compare metaphyseal-anchored (short stems) versus Corail-like stems. RESULTS: After adjusting for the propensity score, we found 11.17% mechanical complications in the uncemented group (n=40, 5.59% subsidence, and 5.59% fractures) versus 13.42% for the cemented group (n=42, 7.99% subsidence, and 5.43% fractures). There was no statistically significant difference between the 2 values (Odds Ratio [OR]=0.64 [95% Confidence Interval [CI]: 0.14-2.85] [p=0.7]). The mortality rate due to cement embolism was 1%. There was no difference in the rate of subsidence (OR=0.55 [95% CI: 0.02-12.5] [p=0.7]), periprosthetic fracture (OR=0.65 [95% CI: 0.13-3.12] [p=0.7]) or infection (OR=0.71 [95% CI: 0.32-1.55] [p=0.4]). However, the operative times were longer in the cemented group (p=0.03 for hemiarthroplasties [mean additional time 16minutes] and p=0.02 for total hip arthroplasties [mean additional time 22minutes]). No difference was observed between the metaphyseal-anchored (short stems) and Corail-like stems regarding operative time, rate of infection, and rate of stem subsidence or periprosthetic fractures. DISCUSSION: This is one of the first studies to highlight cemented stem subsidence when used for femoral neck fractures in elderly patients. Using uncemented stems in this indication is still warranted, especially since they do not bring about more mechanical complications in the first few months. Metaphyseal-anchored short stems seem to give the same results as "standard" stems. However, these findings need to be assessed in the longer term. LEVEL OF EVIDENCE: III; retrospective comparative study.

Cemented Stem Design in Total Hip Arthroplasty: Fixation Philosophies, Biomechanics, and an Updated Classification System.

There is renewed interest in cemented femoral fixation in total hip arthroplasty in the United States, and to fully appreciate the evolution of cemented femoral stem designs, an understanding of their history and design rationale is essential. To adequately study the outcomes of modern-day designs, a comprehensive classification system is also necessary. The biomechanical principles, failure mechanisms, and clinical outcomes associated with various cemented femoral stems are described in this comprehensive review. In addition, an updated version of an existing classification system is described that incorporates the primary design characteristics which differentiate implants currently in use. In this classification, implants are categorized as taper-slip (Type I), which are subdivided by Anatomic (IA), Double-Taper (IB), and Triple-Taper (IC) with subclassification for Traditional and Line-to-Line implants. Composite beam (Type II) implants are similarly divided into Anatomic (IIA), Straight (IIB), and Wedge (IIC) with subclassification for Polished, Satin, or Roughened finish. This classification system provides a basis for comparing cemented femoral stems, thereby improving our understanding of the effect of design characteristics on survivorship to guide future advancements and improve clinical outcomes.

Equivalent revision rates and patient reported outcomes with routine use of a short (125mm) cemented stem for total hip arthroplasty compared to a standard length (150mm) cemented stem. A two surgeon series of 1335 patients.

BACKGROUND: Routine total hip arthroplasty (THA) using a short cemented stem as compared with a standard length cemented stem may have benefits in terms of stress distribution, bone preservation, stem subsidence and ease of revision surgery. Two senior arthroplasty surgeons transitioned their routine femoral implant from a standard 150 mm Exeter V40 cemented stem to a short 125 mm Exeter V40 cemented stem for all patients over the course of several years. We analysed revision rates, adjusted survival, and PROMS scores for patients who received a standard stem and a short stem in routine THA. METHODS: All THAs performed by the two surgeons between January 2011 and December 2021 were included. All procedures were performed using either a 150 mm or 125 mm Exeter V40 stem. Demographic data, acetabular implant type, and outcome data including implant survival, reason for revision, and post-operative Oxford Hip Scores were obtained from the New Zealand Joint Registry (NZJR), and detailed survival analyses were performed. Primary outcome was revision for any reason. Reason for revision, including femoral or acetabular failure, and time to revision were also recorded. RESULTS: 1335 THAs were included. 516 using the 150 mm stem and 819 using the 125 mm stem. There were 4055.5 and 3227.8 component years analysed in the standard stem and short stem groups respectively due to a longer mean follow up in the 150 mm group. Patient reported outcomes were comparable across all groups. Revision rates were comparable between the standard 150 mm stem (0.44 revisions/100 component years) and the short 125 mm stem (0.56 revisions/100 component years) with no statistically significant difference found (p = 0.240). CONCLUSION: Routine use of a short 125 mm stem had no statistically significant impact on revision rate or PROMS scores when compared to a standard 150 mm stem. There may be benefits to routine use of a short cemented femoral implant.

Optimization of culture medium to improve bio-cementation effect based on response surface method.

The main challenge in the large-scale application of MICP lies in its low efficiency and promoting biofilm growth can effectively address this problem. In the present study, a prediction model was proposed using the response surface method. With the prediction model, optimum concentrations of nutrients in the medium can be obtained. Moreover, the optimized medium was compared with other media via bio-cementation tests. The results show that this prediction model was accurate and effective, and the predicted results were close to the measured results. By using the prediction model, the optimized culture media was determined (20.0 g/l yeast extract, 10.0 g/l polypeptone, 5.0 g/l ammonium sulfate, and 10.0 g/l NaCl). Furthermore, the optimized medium significantly promoted the growth of biofilm compared to other media. In the medium, the effect of polypeptone on biofilm growth was smaller than the effect of yeast extract and increasing the concentration of polypeptone was not beneficial in promoting biofilm growth. In addition, the sand column solidified with the optimized medium had the highest strength and the largest calcium carbonate contents. The prediction model represents a platform technology that leverages culture medium to impart novel sensing, adjustive, and responsive multifunctionality to structural materials in the civil engineering and material engineering fields.

Cemented is not superior to cementless total knee arthroplasty for complications: a propensity score matched analysis.

INTRODUCTION: There is continued debate regarding the survivorship and revision rate of cementless versus cemented total knee arthroplasty (TKA) prostheses. This includes the assessment of early revision surgery due to aseptic loosenings and periprosthetic joint infections (PJIs). Studies have not always taken into account the impact of comorbidities, such as diabetes, obesity, and tobacco. Therefore, we compared revisions in a large population of patients undergoing cemented or cementless TKAs at 90 days, 1 year, and 2 years. METHODS: A review of an administrative claims database was used to identify patients undergoing primary TKA, either cementless (n = 8,890) or cemented (n = 215,460), from October 1, 2015 to October 31, 2020. Revision surgery for PJI and aseptic loosening were identified with diagnosis and associated procedural codes at 90 days, 1 year, and 2 years and then compared between groups. A propensity matched-analysis was performed for age, sex, Charles Comorbidity Index (CCI) > 3, alcohol abuse, tobacco use, obesity, and diabetes. Chi square tests assessed statistical significance of differences in the matched cohorts using odds ratios (ORs) with 95% confidence intervals (CIs). A P < 0.05 was defined as statistically significant. RESULTS: Cementless TKA was associated with similar revisions rates due to PJIs at 90 days (OR, 1.04, 95% CI 0.79-1.38, p = 0.83), 1 year (OR, 0.93, 95% CI 0.75-1.14, p = 0.53, and 2 years (OR, 0.87, 95% CI 0.73-1.05, p = 0.17) in comparison to the cemented TKA cohort. The odds ratio of revision due to aseptic loosening was similar as well at 90 days (OR, 0.67, 95% CI 0.34-1.31, 0.31), 1 year (OR, 1.09, 95% CI 0.73-1.61, p = 0.76), and 2 years (OR, 1.00, 95% CI 0.73-1.61, p = 0.99). CONCLUSIONS: This study found a comparable risk of PJI and aseptic loosening in cementless and cemented TKA when controlling for several comorbidities, such as tobacco, diabetes, and alcohol. Therefore, with proper patient selection, cementless TKAs can be performed with expectation of low risks of infections and aseptic loosenings.

Periprosthetic fracture following arthroplasty for femoral neck fracture: is a cemented stem protective?

BACKGROUND: Periprosthetic femoral fractures (PFF) carry significant morbidity following arthroplasty for femoral neck fracture (FNF). This study assessed fracture complications following arthroplasty for FNF and the effect of cement fixation of the femoral component on intraoperative and post-operative PFF. METHODS: Between February 2014 and September 2021, 740 patients with a FNF who underwent arthroplasty were analyzed for demographics, surgical management, use of cement for fixation of the femoral component, and subsequent PFF. Variables were compared with Mann-Whitney or Chi-square as appropriate. Multivariate logistic regression was used to assess independent risk factors associated with intraoperative or post-operative PFF. RESULTS: There were 163 THAs (41% cemented) and 577 HAs (95% cemented). There were 28 PFFs (3.8%): 18 post-operative and 10 intraoperative. Fewer post-operative PFFs occurred with cemented stems (1.63% vs. 6.30%, p = 0.002). Mean time from surgery to presentation with post-operative PFF was 14 months (0-45 months). Mean follow-up time was 10.3 months (range: 0-75.7 months). In multivariate regression, use of cement and THA was independently associated with decreased post-operative PFF (cement: OR 0.112, 95% CI 0.036-0.352, p < 0.001 and THA: OR 0.249, 95% CI 0.064-0.961, p = 0.044). More intraoperative fractures occurred during THA (3.68% vs. 0.69%, p = 0.004) and non-cemented procedures (5.51% vs. 0.49%, p < 0.001). In multivariate regression, use of cement was protective against intraoperative fracture (OR 0.100, CI 0.017-0.571, p = 0.010). CONCLUSIONS: In patients with a FNF treated with arthroplasty, cementing the femoral component is associated with a lower risk of intraoperative and post-operative PFF. Choice of procedure may be based on patient factors and surgeon preference.

Factors influencing the bond strength of additively manufactured crown materials in dentistry: A systematic review of in vitro studies.

OBJECTIVE: The purpose of this systematic review was to investigate how different interventions can impact the bond strength of additively manufactured crown materials after cementation. DATA/SOURCES: Four online databases Ovid MEDLINE, Scopus, Web of Science and Google Scholar were searched up to January 2023. Inclusion criteria were English-language publications, full-text, and in vitro studies only. Exclusion criteria were studies that did not assess the bonding of an additively manufactured crown material to cement or did not conduct any bond strength tests. An assessment of risk of bias was done in accordance with a modified Consolidated Standards of Reporting Trials (CONSORT) checklist. Each study was analysed and compared based on the interventions and bond strength results. STUDY SELECTION: Six studies satisfied the inclusion and exclusion criteria, five of which evaluated photopolymerised resin and one that tested zirconia manufacturing via 3D printing. All studies observed a low risk of bias. The interventions applied included the type of surface pretreatments, airborne-particle abrasion pressure, cement type, taper of crown, and artificial aging. Three studies compared the bonding performance to milled materials. CONCLUSIONS: The bond strength of crown materials additively manufactured from photopolymers presented high values and are comparable to milled materials. The systematic review demonstrated there was no definite superior cement type, but airborne-particle abrasion with alumina was generally recommended. There is a clear gap in the literature regarding the bond strength of additively manufactured crowns. Therefore, further research is necessary to evaluate its clinical applicability for permanent restorations. CLINICAL SIGNIFICANCE: Factors influencing the bond strength of additively manufactured crown materials should be evaluated so dental professionals can adopt procedures that promote the strongest bond.

Identification and extraction of cementation patterns in sand modified by MICP: New insights at the pore scale.

Microbially induced calcium carbonate precipitation (MICP) is an environmentally friendly technology that improves soil permeability resistance through biocementation. In this study, 2D microscopic analysis and 3D volume reconstruction were performed on river sand after 24 cycles of bio-treatment based on stacked images and computed tomography (CT) scanning data, respectively, to extract biocementation patterns between particles. Based on the mutual validation findings of the two techniques, three patterns in the biocemented sand were identified as G-C-G, G-C, and G-G. Specifically, 2D microscopic analysis showed that G-C-G featured multi-particle encapsulation and bridging, with a pore filling ratio of 81.2%; G-C was characterized by locally coated particle layers, with a pore filling ratio of 19.7%; and the G-G was marked by sporadic filling of interparticle pores, with a pore filling ratio of 11.7%. G-C-G had the best cementation effect and permeability resistance (effective sealing rate of 68.5%), whereas G-C (effective sealing rate of 2.4%) had a relatively minor contribution to pore-filling and flow sealing. 3D volume reconstruction showed that G-C-G had the highest pore filling rate, followed by G-G and G-C. The average filling ratios of area and volume for G-C-G were 83.979% and 77.257%, respectively; for G-G 20.360% and 23.600%; and for G-C 11.545% and 11.250%. The analysis of the representative element volume (REV) was conducted, and the feasibility and reliability of the micro-scale pattern extraction results were confirmed to guide the analysis of macro-scale characteristics. The exploration of the effectiveness of cementation patterns in fluid sealing provides valuable insights into effective biocementation at the pore scale of porous media, which may inspire future research.

Prolonged post-washing in ethanol decreases bond strength of additively manufactured crown materials.

OBJECTIVES: This study aimed to investigate the effect of post-washing duration and crown thickness on the bond strength between additively manufactured crown materials and dental cement in vitro. METHODS: Rectangular-shaped specimens of two thicknesses (1.5 and 2.0 mm) were additively manufactured from permanent VarseoSmile Crown (VC) and long-term temporary NextDent (ND) materials. The specimens were post-washed (n = 160) in ethanol for 5 min, 10 min, 1 h, and 8 h then cemented with dual-cure resin cement. Twenty PMMA (TC) were milled as a control. A chevron-notch test was performed to measure the maximum load until failure (N). Interfacial bond strength (J/m2) was calculated and statistically analysed. The mode of failure was analysed by scanning electron microscopy (SEM). RESULTS: There was a significant difference in the bond strength between all groups (p < 0.01). VC at 1.5mm thickness post-washed for 10 min showed the highest mean bond strength (1.77 ±0.96 J/m2) while VC at 2.0mm thickness post-washed for 8 h showed the lowest (0.22 ±0.10 J/m2). Exposure to ethanol for 8 h resulted in lower bond strength. Within the type of material, there were no differences in bond strength between the thicknesses when post-washed for the same duration. CONCLUSIONS: Prolonged post-washing of AM crown materials can significantly decrease the bond strength to resin cement. There were no differences between the permanent and long-term temporary AM materials. When post-washed for 5 min, AM materials observed comparable or higher bond strength values compared to PMMA. CLINICAL SIGNIFICANCE: The output of this research serves as a guide for dental practitioners, emphasising the importance of adhering to correct post-washing procedures for optimal bond strength of additively manufactured crown materials.

Comparison of osteolysis around 3 different cement restrictors in total hip arthroplasty.

BACKGROUND AND AIM: Several studies reported osteolysis around polyethylene glycol/polybutylene terephthalate (PEG/PBT) based femoral cement restrictors. Our goal was to evaluate and compare osteolysis around 3 different plug designs: the slow biodegradable PEG/PBT cement restrictor; the fast biodegradable gelatin cement restrictor; and the non-biodegradable polyethylene plug. PATIENTS AND METHODS: In a retrospective multicentre cohort study chart data were extracted of patients who received a total hip arthroplasty between 2008 and 2012. A total of 961 hips were included. Cortical ratio between inner and outer cortices at the centre of the plug was measured on routine postoperative follow-up moments. Median follow up of all 3 hospitals was 3.5 years (1.4-7.3). The primary outcome was evidence of osteolysis (i.e. the difference in cortical ratio [CR]) on anteroposterior (AP) radiographs at final follow-up. RESULTS: Progressive osteolysis was found around the PEG/PBT cement restrictor represented by a significantly increasing cortical ratio (ΔCR 0.067 (95% CI, 0.063-0.071). Distance from tip prosthesis to plug and size of the plug were found to be independent factors in predicting increased cortical ratio. CONCLUSIONS: Our multicentre cohort shows increase of cortical ratio around the PEG/PBT cement restrictor which progresses over time. Physicians should be aware of this fact and are advised to intensify follow-up of patients who received this cement restrictor.