Osseointegration Research Articles

Influence of the use of an adhesive connection on the joint strength of modular hip endoprostheses.

Modular hip implants enables a more precise adaptation of the prosthesis to the patient's anatomy. However, they also carry the risk of increased revision rates due to micromotion at the taper junction. In order to minimize this risk, one potential solution is to establish an adhesive bond between the metal taper junctions. Load-stable bonding techniques, already successfully employed in dentistry for connecting materials such as metals and ceramics or different alloys, offer a promising approach. Nevertheless, the bond strength of tapered adhesive bonds in modular hip implants has not been investigated to date. Twenty-eight tapered junctions, consisting of a taper (female taper) and a trunnion (male taper) were turned using TiAl6V4 ELI (n = 16) and CoCr28Mo6 (n = 12). The process parameters cutting speed (vc = 50 m/min or 100 m/min) and feed (f = 0.1 mm, 0.05 mm or 0.2 mm) were varied for the trunnions. For each set of process parameters, one trunnion and one taper were additionally subjected to sandblasting. To investigate the effect of geometry, angular mismatch in the samples were measured. The taper pairs were bonded with a biocompatible adhesive, and push-out tests were subsequently performed. The push-out forces generated from the taper connections where both tapers were sandblasted showed a mean push-out force of 5.70 kN. For the samples with only the trunnion sandblasted, the mean force was 0.58 kN, while for the samples with only taper sandblasted the mean push-out force was 1.32 kN. When neither of the tapers was sandblasted the mean push-out force was 0.91 kN. No significant effect of the process parameters on the push-out force was observed. Only the reduced valley depth Svk showed a slight correlation for the CoCr28Mo6 samples (R2 = 0.54). The taper pairs with taper mismatch (between trunnion and taper) greater than |0.1°| did not show lower push-out forces than the specimens with lower taper mismatch. Sandblasted and adhesive-bonded tapered connections represent a viable suitable alternative for modular hip implant connections. Slight differences in taper geometry do not result in reduced push-out forces and are compensated by the adhesive. In mechanically joined tapers these differences can lead to higher wear rates. Further investigation under realistic test conditions is necessary to assess long-term suitability.

Experimental and numerical investigations on the bond-slip behavior of the interface between geopolymer concrete and steel tube

This study conducts push-out tests on eight geopolymer concrete filled steel tube column specimens with varying design parameters to evaluate the effects of steel tube wall thickness, concrete strength, and the presence of welded longitudinal ribs on the bond-slip performance at the interface between geopolymer concrete and steel tube. The study analyzes the influence mechanism of chemical bonding force, mechanical bite force, and friction resistance on bond strength and a three-stage bond-slip constitutive relationship is established. The results indicate that steel tube strain increases with height, with significant strain observed at the welding structure and the fixed end of the steel tube. The length-to-diameter ratio, diameter-to-thickness ratio, concrete strength, and construction measures of the steel tube are identified as key factors in enhancing interfacial bonding performance. The presence of welded longitudinal ribs on the inner wall of the steel tube significantly improves the interface bonding. The calculated bond strength ratios, compared with the test results, fall within an 11% margin, demonstrating good agreement.

IMPLANTES DENTÁRIOS INSTALADOS EM PACIENTES PORTADORES DO VIRUS DA IMUNODEFICIENCIA HUMANA (HIV)

The Human Immunodeficiency Virus (HIV) compromises the immune system and, as it progresses, causes acquired immunodeficiency syndrome (AIDS), characterized by the emergence of opportunistic infections. Transmission occurs mainly through sexual contact or via blood and, in Brazil, between 1980 and 2022, more than 1 million cases of AIDS were recorded. Regarding implantology, patients with HIV face oral complications such as gingivitis and candidiasis, and although the impact of osseointegrated implants in these patients is not yet entirely clear, prior evaluation of bone health and conditions is essential. This research aims to describe the care in the osseointegration process in HIV-positive patients, investigating the possible complications and the importance of biosafety, in addition to highlighting the relevance of treatment to improve the quality of life of these patients. The methodology used was the bibliographic review, using articles published between 2012 and 2022 in Portuguese. Oral rehabilitation with dental implants in HIV-positive patients has gained importance due to the increase in life expectancy provided by antiretroviral therapy. These patients, with an improved quality of life, are looking for viable options to replace missing teeth, with dental implants being an attractive alternative. Although the literature on the topic is limited, the results indicate that the success rates of implants in patients with HIV are similar to those of healthy patients, as long as the treatment considers the immune status. However, specific care is needed, such as monitoring for possible complications resulting from the continuous use of antiretrovirals, which can cause liver and kidney problems. Additionally, strict biosafety protocols are essential to ensure the safety of patients and healthcare providers. Further research is recommended to clarify outstanding issues and improve pre- and postoperative care, providing more predictable outcomes and greater safety in treatment with osseointegrated implants.

Effects of laser treatment on bond strength of epoxy resin and calcium silicate-based sealers: a systematic review and meta-analysis of in vitro studies.

This study aimed to systematically review the effect of laser treatment on the bond strength of epoxy resin-based and calcium silicate-based endodontic sealers to root dentine. The search encompassed four databases: PubMed/MEDLINE, EMBASE, Scopus, and ISI Web of Science. Inclusion criteria were limited to in vitro studies conducted on extracted human teeth evaluating bond strength in megapascals (MPa) of either epoxy resin-based or calcium silicate-based sealers, using the push-out test. Two independent reviewers appraised the methodological quality of the selected studies to assess the risk of bias. Meta-analysis was performed for different laser types, endodontic sealers, and control groups. Standard Mean Difference and 95% Confidence Interval values were calculated. 17 studies met the inclusion criteria for qualitative synthesis, and 15 for quantitative analysis. Meta-analyses revealed that certain lasers (Er,Cr:YSGG, Er:YAG) significantly increased bond strength for epoxy resin-based sealers when compared to negative controls (inert solutions), but did not show a significant advantage over EDTA agent. For calcium silicate-based sealers, laser treatment did not show significant enhancement in bond strength compared to either inert solutions or EDTA. The subgroup analysis suggested that erbium lasers, especially in the PIPS mode, potentially increase the bond strength of epoxy resin-based sealers. Laser treatment enhances the bond strength of epoxy resin-based sealers compared to inert solutions, but not more than EDTA. For calcium silicate-based sealers, laser treatment does not significantly improve bond strength over inert solutions or EDTA. Laser treatment increases the bond strength of epoxy resin-based sealers.

Major considerations of maxillary/mandible osteonecrosis caused by bisphosphonates in the dental implant scenario: a systematic review

Introduction: The literature has shown that several patients with a history of bisphosphonate treatment appear to be at risk for medication-related osteonecrosis of the jaw (MRONJ) osteonecrosis of the jaw. Objective: It was analyzing the use of BP associated with dentistry. Because it is a possible alternative for the reduction of loss and increase in bone density, as well as for the possibility of osteonecrosis, which requires therapeutic and preventive measures in the involvement of invasive practices such as dental implants. Methods: The PRISMA Platform systematic review rules were followed. The search was carried out from April to June 2024 in the Scopus, PubMed, Science Direct, Scielo, and Google Scholar databases. The quality of the studies was based on the GRADE instrument and the risk of bias was analyzed according to the Cochrane instrument. Results and Conclusion: 85 articles were founded, and 54 articles were evaluated and 30 were included in this systematic review. Considering the Cochrane tool for risk of bias, the global assessment resulted in 24 studies with a high risk of bias and 18 studies that did not meet GRADE and AMSTAR-2. Most studies showed homogeneity in their results, with X2 =81.9% >50%. It was concluded that osteoporosis is a metabolic condition that affects alveolar bone density, but does not present problems for the installation of osseointegrated implants, as long as there is sufficient bone mass in the region where the tooth will be implanted. It suggests to the dental surgeons the knowledge of the diagnosis so that it makes a careful evaluation, directing the professional to observe the quality of the bone through routine image examinations. Further, alendronate sodium is used to decrease bone resorption, the drug should be considered as an adjunctive therapeutic agent for the treatment of osteoporosis.

Mechanical properties of short rebar connectors in ultra-thin lightweight composite decks

To address the challenge of shear connector applicability in ultra-thin Lightweight Composite Decks (LWCDs), a novel type of Short Rebar Connectors (SRCs) was proposed. With the height of 16–20 mm, the connectors are well-suited for ultra-thin LWCDs with Ultra-High-Performance Concrete (UHPC) thicknesses within 35 mm. The mechanical performance of SRCs was investigated through pull-out tests, static and fatigue push-out tests. The results demonstrate that SRCs exhibit excellent tensile and shear resistance, with the maximum pull-out and shear capacities of 80.4 kN and 948 kN, respectively. The shear stiffness of SRCs is twice that of traditional stud connectors. From fatigue push-out tests, a design strength of 69.2 MPa at 2 million cycles was obtained. Finite Element Method (FEM) calculations for practical bridge engineering SRCs layout recommend arranging SRCs with a spacing of 200 mm × 200 mm.

Analyzing research trends and developments in osseointegration in patients with extremity amputations: Systematic bibliometric analysis and research recommendations.

Bone-anchored protheses (BAPs) by means of osseointegrated implants are increasingly being used in amputees with socket-related issues. Clinical advancements are being published by more and more centers worldwide. Although the number of publications and interest in BAP is growing, a systematic evaluation of scholarly output is lacking. To identify scholarly output, understand research trends and make research recommendations in the clinical field of BAP. Systematic searches in Medline All, Embase, Web of Science Core Collection, Cochrane Library, and Google Scholar were completed in February 2023. The results were deduplicated, screened, and assessed for quality by independent reviewers. Inclusion criteria were as follows: clinical studies and BAP in the extremities. Articles were excluded if they were animal or fundamental studies, nonclinical reports, had a study population less than 10 patients, or BAP was performed in areas other than extremities. One hundred twelve articles were included and published between 1993 and 2023. An annual growth rate of 10.3% was found and research was published in 62 different journals. Prosthetics and Orthotics International, Clinical Orthopaedics and Related Research and The Bone & Joint Journal were the most prolific journals. Hagberg K, Aschoff HH, and Branemark R were major contributors to BAP research. Collaborations are predominantly among high-income countries. Main research trends were on rehabilitation, questionnaires, complication managements, and implant treatment. Research on BAP shows an increasing global trend, highlighting key research areas and authors. A unified global research agenda, stakeholders' collaborations, and consensus are essential for addressing knowledge gaps and development future direction of BAP.

Does an Osteoporosis-like Condition Jeopardize the Osseointegration Process around Dental Implants Placed in Animal Models? A Systematic Review.

Knowing that osteoporosis is a metabolic disease that could decrease dental implant success and survival, the purpose of this review was to gather information on the characteristics of implant osseointegration in animal models of induced osteoporosis. By pointing out the role of some factors that could improve the success rate in these situations, this study aimed to enhance the knowledge about this process that can be further translated to clinical designs. A systematic search in PubMed/Medline, Lilacs, Cochrane Library, Scopus and Web of Science was conducted to identify information between 2002 and 2023 regarding osseointegration of dental implants in animal models of induced osteoporosis. The following search strategy was utilized and adjusted to each database: (((dental implant) AND (Osseointegration)) AND (osteoporosis)) AND/OR (osteoporosis treatment). The inclusion criteria were animal studies in English, involving the placement of an osseointegrated implant in osteoporotic bone, and evaluating bone to implant contact (BIC) %. Exclusion criteria were studies in humans, in vitro studies, procedures involving any kind of bone graft and studies evaluating medication related osteonecrosis of the jaw. A standardized data extraction form was used to record data for each study, covering article title, date, authors, number of animals, purpose of study, type of analysis used by authors, follow-up, type of implant, test and control groups, intervention and conclusions. The risk of bias of the included studies was assessed using the Systematic Review Centre for Laboratory animal Experimentation (SYRCLE) Risk of Bias tool.20 Results: A total of 204 articles were found for evaluation and selection. All of the 43 selected studies evaluated the bone-implant contact (BIC) %. Other parameters such as bone to implant mechanical interface, bone area (BA) and bone volume (BV) ratio were also evaluated in some of the studies. There was a tendency for compromised results of implant osseointegration in the presence of osteoporosis. Modification of the implant surface, systemic and local use of anti-resorptive drugs and other substances, showed benefits for the implant success in osteoporotic sites. Still, no consensus among studies on the superiority of systemic medications in improving the process of peri-implant bone repair, was observed. Although it is possible to improve the osseointegration of implants in osteoporotic bone, either by using systemic or local factors, the metabolic bone syndrome caused by osteoporosis can jeopardize the osseointegration of dental implants.

Comparative Evaluation Of The Effect Of Different Chelating Agents On The Push-Out Bond Strength Of A Bioceramic Sealer: An In-Vitro Study

Aim: This study aimed to assess how the push out bond strength of a bioceramic sealer (Meta CeraSeal) is affected by three different chelating agents: 17% EDTA, 7% Maleic acid, and 5% Pentetic acid. Methodology: 60 mandibular premolars were shaped using Pro Taper Gold rotary file upto size F2. The canals were irrigated with 2ml of 5.25% sodium hypochlorite (NaOCl) between instrumentation and then the NaOCl was removed by rinsing with five milliliters of distilled water.. The 60 specimens were divided into 4 groups of 15 each, in a random manner, depending on the final irrigating solution: Group 1 (n=15): 17% EDTA,Group 2 (n=15): 7% Maleic acid,Group 3 (n=15): 5% Pentetic acid and Group 4 (n=15): 0.9% Saline. The canals were obturated with Meta CeraSeal coated gutta percha using single cone technique. Access to cavities were sealed and the specimens were sectioned to obtain three horizontal sections at distances of 12, 6, and 2 mm from the apex (coronal, middle, and apical root sections, respectively). A universal testing machine was used to apply the push-out test. Results: The push out bond strength was significantly higher for 5% Pentetic acid as compared to 17% EDTA and 7% Maleic acid (p<0.05). Also, the apical third exhibited the lowest push out bond strength value in all the groups. Conclusion: Within the limitations of the study, it can be concluded that, in comparison to the other tested groups, 5% pentetic acid has higher potential to facilitate the bonding of the bioceramic sealer Meta CeraSeal to root dentin

The Effect of Silver Nanoparticles on Bond Strength of Calcium Silicate-Based Sealer: An In Vitro Study

The aim of this study was to evaluate the bond strength of the calcium silicate-based sealer (CSS) modified with the silver nanoparticles (AgNPs) using the single-cone technique (SC) and the continuous wave condensation (CWC) technique, measured by a universal testing machine. The AgNPs and the modified sealers were characterized by scanning electron microscopy and transmission electron microscopy. One hundred single-rooted extracted human permanent teeth with a single root canal were cleaned and shaped with a Protaper Next system. The teeth were randomly divided into four groups (n = 25) as follows: Group 1, canals were obturated using the SC technique with TotalFill® BC Sealer. Group 2, canals were obturated using the SC technique with TotalFill® BC Sealer mixed with AgNPs. Group 3, canals were obturated using the CWC technique with TotalFill® HiFlow BC Sealer. Group 4, canals were obturated using the CWC technique with TotalFill® HiFlow BC Sealer mixed with AgNPs. After two weeks, 1 mm-thick dentin slices were cut and exposed to a push-out bond strength test using a universal testing machine. Specimens were examined under a digital microscope to determine the mode of failure. Statistical analysis was performed using ANOVA and Tukey multiple comparison tests (p < 0.05). The nanoparticle characterization revealed a spherical morphology with no obvious aggregations. The results showed that group 4 had the highest dislodgement resistance compared to all groups (p < 0.05). Group 4 was significantly higher in push-out bond strength value than group 1 (p < 0.001) and group 3 (p < 0.003), but not significantly higher than group 2. Cohesive failure was the most prevalent failure mode among all groups. It can be concluded that the incorporation of silver nanoparticles into the calcium silicate-based sealer significantly increased the bond strength. The warm obturation approach demonstrated significantly higher resistance to dislodgment as compared to the single-cone technique.

Fiber post cemented using different adhesive strategies to root canal dentin obturated with calcium silicate-based sealer

BackgroundCalcium silicate-based sealer has favorable properties for root canal filling, including hydroxyapatite formation during the setting process. However, this process can cause difficulty during post space preparation when the sealer is set. Additionally, the remaining sealer could interfere with the bond strength of fiber post to root canal dentin. The different adhesive strategies and fiber post cementation time may affect the bond strength of the fiber post. Thus, the objective of this study was to evaluate the effect of etching modes of Scotchbond™ Universal Plus adhesive and post cementation time on the push-out bond strength of a fiber post cemented in root canals obturated with calcium silicate-based sealer.MethodsFifty-four teeth were randomly allocated to 6 groups (n = 9) based on etching modes: self-etch (SE) or etch-and-rinse (ER); post space preparation and cementation time: immediate (Im) or 7-day delayed (De): Im-Im, Im-De, and De-De. The root canals were obturated with calcium silicate-based sealer and the post space preparation was performed. The fiber post was cemented using RelyX™ Universal resin cement according to each group’s design. For the push-out bond strength test, 1-mm slices of the coronal, middle, and apical regions were tested using a universal testing machine. The failure mode analysis was determined using a stereomicroscope. The data was analyzed with three-way analysis of variance.ResultsNo negative effects of etching modes, post space preparation or cementation time on push-out bond strength were detected (p > 0.05). Additionally, the root canal region also did not significantly affect the bond strength (p > 0.05).ConclusionNo significant differences were observed between the etching modes, post space preparation and cementation time and among root canal regions.Clinical relevanceThe different etching modes of adhesive and post cementation time did not affect the bond strength of fiber post in calcium silicate filled-root canal.

Failure of the SRC under freeze- thaw cycles by the push-out tests

This paper explores the impact of freeze-thaw cycles, the thickness of the protective layer, embedment length, and volumetric hoop ratio on the bond performance at the SRC interface, assessed through freeze-thaw and push-out tests. Results from SEM indicated significant cracking in concrete exposed to freeze-thaw cycles, with an increase in both the number and diameter of pores. Despite significant damage to the concrete exterior, the interface exhibited considerably less deterioration. Following 200 freeze-thaw cycles, the specimens displayed a maximum crack depth of 2.3 mm and a porosity rate of 35.1 %. As the cycles progressed, the failure mode of specimens under push-out loading transitioned from splitting to interfacial shear failure. Notably, the length of cracks on the end surfaces was markedly reduced, and the majority of specimens exhibited minimal cracking on the side surfaces. Additionally, interfacial bond stress decreased progressively with the increasing number of cycles. The ultimate bond stress declined more rapidly than residual bond stress, with the rate of decrease stabilizing after surpassing 100 cycles. Enhancements in protective layer thickness, embedment length, and volumetric hoop ratio effectively mitigated the reductions in bond stress. Among these, the protective layer had the most significant impact, followed by the volumetric hoop ratio, while embedment length had the least influence. The study concludes with proposed formulas for calculating bond stress and slip eigenvalues after freeze-thaw cycles, integrating experimental results and theoretical analysis.

A Real Time Delphi Study on the Challenges and Adverse Events to Percutaneous Osseointegrated Implant Integration and Long-Term Fixation in Limb Amputation

Percutaneous Osseointegrated Implants (POI) affix artificial limbs to the body after amputation. Several adverse events challenge mainstream uptake of this technology. This study aims to achieve a consensus regarding “the challenges and adverse events to POI integration and long-term fixation in limb amputation”. We sought a panel of clinical experts divided by profession into surgical, clinical, or clinical academic categories. We used a real time eDelphi method to develop consensus on both the challenges and adverse event items, enabling anonymity, iteration, controlled feedback, and statistical aggregation of group responses. The full panel agreed that the most impactful items are amongst 10 key challenges and eight adverse events. Panellists were in consensus regarding the five most impactful challenges, which were, in decreasing order: patient selection, absence of a multidisciplinary team, design of the implant, soft tissue stability and an experienced surgical team. Panellists considered the five most impactful adverse events, in decreasing order, to be the following: no biological fixation, deep infection, aseptic loosening, no mechanical fixation, and implant breakage. Consensus was obtained on implant breakage and deep infection items. The proportion of consensus from the whole panel across all items was in line with the literature, and we observed an improvement in consensus once the panel was stratified based on job, expertise and implant system.

The effect of zinc-containing calcium phosphate coating on the osseointegration of transcutaneous implants for limb prosthetics

Introduction Increasing the integration of transcutaneous implants is an important goal for their application in clinical practice.The purpose of the work was to evaluate the osseointegration of transcutaneous titanium implants with calcium-phosphate coating containing zinc ions.Materials and methods The studies were performed on 12 male rabbits, who underwent implantation of an original implant into the tibial stump. After implantation, a compression device was installed on the bone, maintaining a load of 3.5 N for 5 weeks. Duration of observation was 26 weeks. The animals were divided into two groups: a control group (n = 6) with an implant without coating and an experimental group (n = 6) with a zinc-substituted calcium-phosphate coated implant.Results The implant fell out in one case in animals from the control group; no cases of implant loss were noted in the experimental group. It was revealed that the weight concentration of Ca and P in all zones of the bone-implant block of the animals in the experimental group significantly exceeded similar indicators in the control group. In the control group, long-term persistence of high levels of C-reactive protein was noted, which was not observed in the experimental group.Discussion This series of studies has shown that an implant with a zinc-modified calcium-phosphate coating exhibited a more effective integration, in contrast to an uncoated product. The absence of serious adverse reactions to the tested products indicates acceptable tolerability and safety of its use.Conclusion The implants with a zinc-modified calcium-phosphate coating showed signs of more effective osseointegration compared to the product without additional coating.

Corrosion failure analysis of interfacial bond performance in circular seawater sea-sand concrete encased weathering steel structures

This paper investigated the bond-slip behavior of circular seawater sea-sand concrete encased weathering steel (CSSCEWS) structures after chloride-induced corrosion. Electrochemical corrosion tests and push-out tests were conducted on fifteen designed CSSCEWS specimens. The results revealed that the corrosion ratio and steel section type distinctly influenced the interfacial bond performance. Both the ultimate and residual bond strengths decreased with the increase of the corrosion ratio, and the decline rate slowed down gradually. Compared to the uncorroded specimens, the average damage ratio of the ultimate strength of the specimens with a corrosion ratio of 8% is 25.9%, while the average damage ratio of the residual strength is 49.1%. The bond toughness continuously decreased with prolonged corrosion, while the bond stiffness and energy dissipation index first increased and then decreased. Additionally, formulas for calculating the corroded bond strengths of CSSCEWS specimens were proposed. Considering the strength damage due to corrosion and the stiffness damage due to slip, a three-stage bond-slip constitutive model was proposed. Finally, this model was applied to the nonlinear spring elements in finite element modeling to effectively simulate the interfacial bond behavior during the loading of corroded CSSCEWS specimens.

Investigation of the Effect of Indirect Ultrasonic Force and Different Cements on the Bond Strength of Glass Fiber Posts in Teeth with Different Post Space Preparation Methods

(1) Background: The main aim of this study was to investigate the effects of different cements (Panavia V5, RelyX U200) and placement techniques (indirect ultrasonic vibration and manual method) on the bond strength of glass fiber posts in teeth with different post space preparation methods and to evaluate the failure types. (2) Methods: A total of 120 human upper central teeth were collected for the study. One week after root canal treatment, 10 mm long post space preparation was performed using post drills. Post spaces were irrigated in three different ways, namely NaOCl, NaOCl + EDTA solutions, and passive ultrasonic irrigation of NaOCl and EDTA solutions. Glass fiber posts were divided into two groups for resin cement systems, namely RelyX U200 (3M ESPE) or Panavia V5 (Kuraray Medical). Two different methods, namely the indirect ultrasonic vibration and the manual method, were applied for post placement. Then, 1.2 mm sections were taken from the middle and coronal regions of the inserted fiber posts for a push-out test. (3) Results: the Irrigation × Cement (p = 0.002), Cement × Section (p = 0.043) and Placement × Section (p = 0.049) pairwise interactions were statistically significant. (4) Conclusions: in our study, the effects of different post cavity preparations, different cement types, and different placement techniques on the bond strength of the fiber post were observed.

Fatigue Life Prediction for Stud Shear Connectors Based on a Machine Learning Model

The shear connector of a steel composite bridge is designed by predicting fatigue life using the fatigue strength curves (S-N curve) based on push-out test results. The fatigue strength curves of the current design codes present only a linear relationship between the stress range and fatigue life on a log scale based on push-out experiment results. However, an alternative to the current empirical formula is necessary for the fatigue design of shear connections involving many detailed variations or high strength steel materials. This study collected and reanalyzed data from push-out fatigue tests to determine the factors influencing fatigue life and propose a machine learning-based fatigue life prediction model. The proposed machine learning model demonstrated an improvement in predictive performance of approximately 2 to 8 times compared to the existing design codes when evaluated against experimental data. Feature importance analysis based on the proposed model revealed that the stress range most significantly influenced fatigue life prediction. Model validation results indicated that the proposed model provided reliable predictions with accuracy and generalization performance. Moreover, it effectively accounted for uncertainty by incorporating features previously overlooked in existing design codes. Plans for fine-tuning pretrained models were also discussed.

Experimental Analysis of the Mechanical Behavior of Shear Connectors for Precast Sandwich Wall Panels When Subjected to the Push-Out Tests

Precast concrete sandwich panels consist of two outer layers connected by a central connector and an inner insulating layer that enhances thermal and acoustic performance. A key challenge with these panels is eliminating thermal bridges caused by metallic connectors, which reduce energy efficiency. PERFOFRP connectors, made from perforated glass fiber-reinforced polymer (GFRP) sheets, have been proposed to address this issue. These connectors feature holes that allow concrete to pass through, creating anchoring pins that enhance shear resistance and prevent the separation of the concrete layers. This research aimed to evaluate the effect of the diameter and number of holes on the mechanical strength of PERFOFRP connectors. Three diameters not previously reported in the literature were selected: 12.70 mm, 15.88 mm, and 19.05 mm. A total of 18 specimens, encompassing 6 different configurations with varying numbers of holes, underwent push-out tests. The most significant resistance increase was a 15% gain over non-perforated connectors, observed in the configuration featuring three holes of 19.05 mm. The connections exhibited rigid and nearly linear behavior until failure.

Morphological Analysis and Bond Strength to Root Canal Dentin of Endodontically Treated and Retreated Teeth: An Ex Vivo Study.

To assess the bond strength and the hybrid layer (HL) micro-morphological characteristics at the cement-dentin interface (CD-i) between root canal walls and two adhesive resin cements [self-etch (SERc) and self-adhesive (SARc)] in root-canal-treated (RCT) and naturally aged retreated teeth (RCR-T). Vital (n = 16) and RCT (n = 16) teeth were, respectively, endodontically treated or retreated. Fiber posts were luted either with SERc (Clearfil Universal Bond Quick + DC Core Plus) or SARc (iCEM). Samples were then sectioned into 1 mm thick slices perpendicular to the fiber post and submitted to push-out bond strength test. Vital (n = 4) and RCT (n = 4) first maxillary molars were also selected and prepared to evaluate CD-i morphology through confocal laser scanning microscopy (CLSM). Three-way analysis of variance (ANOVA) and Tukey post-hoc tests were assessed to statistically analyze the obtained data (p 0.05). Bond strength was significantly jeopardized in retreated teeth and in the root apical half, while the cements had no significant influence. Most failures occurred between dentin and resin cement. HL thickness was also hindered in retreated teeth. iCEM produced a thinner HL compared to SERc. Resin tag formation was significantly hampered in the root apical half. SARc performed as well as SERc on aged RCT radicular dentin. Clinicians can rely on simplified one-step luting systems when adhesion is required in unfavorable substrates such as the root canal post space of aged RCT teeth.

Comparative evaluation of the strength of adhesion by push-out bond strength tests on endodontic posts cemented with different resinous types of luting cements: An in vitro study

INTRODUCTION. Endodontic posts play a vital role in strengthening debilitated teeth. They are luted into the radicular space using dental cements that are generally resinous. Given that the forces faced by human teeth are loading in nature and the stresses are accumulative, the bond strength of the interfaces at both the radicular dentin and luting agent and the endodontic post and the luting agent needs to be evaluated. Micro pushout bond strength (POBS) testing is done to determine these strengths. This experimental, in vitro study evaluated the adhesion strength of endodontic posts cemented with different resin-based luting agents using micro-POBS.MATERIALS AND METHODS. A total of 30 human lower incisors were selected and divided into three groups (n=10), based on the type of adhesive resin cement used for luting. Prefabricated endodontic fiber posts were inserted into the root canals of each tooth, and different resin types of cement – Estecem II, Multilink Automix, and Relyx Ultimate. were used to cement the fiber posts. The micro-POBS test measured the bond strength of the cemented pins to the root canal dentin.RESULTS. The results showed that the mean POBS of Group B was higher than that of Group A and Group C. The difference between the mean POBSs of Group A and Group C was not statistically significant (p>0.05).CONCLUSION. The resin adhesive cement used can affect the POBS of endodontic posts to root canal dentin. Clinicians should choose the appropriate resin cement for cementing endodontic posts to ensure a strong and durable bond for a good clinical prognosis.