Osseointegration Research Articles

Push-Out Analysis on the Shear Performance of a New Type of Bellow-Sleeved Stud

For continuous steel–concrete composite girder bridges based on the post-combined method, the conventional rectangular group studs contribute to the isolation of the steel girder and the concrete slab before prestressing, leading to the majority of prestress forces being introduced to the concrete slab. However, rectangular-group stud holes cause the prestress forces to be unevenly distributed. In this study, a new type of bellow-sleeved stud (BSS) was developed to mitigate the weakening effects of rectangular group stud holes on the slab. A steel corrugated sleeve with a diameter of 60 mm was employed to cover the stud, which served as an internal formwork to prevent the concrete from bonding with the root of the stud. After prestressing was complete, the steel sleeve was filled with ultra-high-performance concrete (UHPC) to create a reliable combination between the concrete slab and the steel girder. To investigate the shear performance of this new type of connection, eight push-out test specimens were designed, and finite-element models were built. This study drew a comparison between the BSS and the ordinary headed stud (OHS). The research findings suggested that the BSS is subjected to less bending–shear coupling and offers a 4.5% increase in shear strength and a 31.9% increase in shear stiffness compared with the OHS. The study also analyzed the structural parameters influencing the shear performance of the BSS. It is found that the steel sleeve of the BSS has a negative effect on shear performance, but this can be mitigated by infusing high-strength material into the sleeve. Furthermore, the study examined the effect of construction quality on shear performance and suggested that sleeve deviation and grout leakage considerably reduced the shear performance of the BSS. Accordingly, strict control over the construction quality of the BSS is necessary.

Evaluation of innovative fluroapatite /silicon dioxide modified zirconia nanocomposites coated on Ti–13Nb–13Zr alloy for dental implant application

Dental implants are intended to function as a durable method for replacing missing teeth. A biocompatible dental alloy is used to achieve integration with the jawbone through Osseointegration. This creates a strong base for the implant, allowing it to withstand the mechanical forces generated during biting and chewing. Dental alloys are commonly subjected to various mouth conditions known for their intricate corrosion potential. Corrosion can weaken the structural integrity of the implant, causing issues such as implant loosening, micro-motion at the implant-bone contact, implant fracture, allergic reactions, toxicity, and possible disruption of the Osseo integration process. To improve the alloy's corrosion resistance and biocompatibility, its surface can be altered using nanocomposite materials. The materials provide a protective coating to the alloy, creating a physical barrier that effectively prevents corrosive substances from reaching the underlying bulk material. This study involves modifying the surface of the dental alloy Ti–13Nb–13Zr with Fluroapatite (FAP)/Silicon dioxide (SiO2) modified zirconia (ZrO2) nano composites. The altered surfaces are then studied in simulated body fluid and artificial saliva solutions using in vitro methods. The FAP/SiO2 modified ZrO2 nanocomposites is applied onto a Ti–13Nb–13Zr alloy utilizing Electrophoretic deposition and Dip coating techniques. The coated samples were analysis utilizing FTIR, XRD, and SEM with EDS. Corrosion analysis was carried out on coated and uncoated samples using Electrochemical methods in simulated body fluid and artificial saliva solution. The biocompatibility is assessed using MTT assay, contact angle, and immersion testing in both SBF and Artificial saliva. EIS and corrosion study results show that FAP/SiO2 modified ZrO2 nanocomposites coated Ti13Nb13Zr alloy has high polarization resistance, low corrosion rate, and good charge transfer resistance, indicating excellent corrosion resistance. The contact angle study showed that the surface-modified Ti13Nb13Zr alloy is superhydrophilic, increasing implant surface osseointegration. Cell viability measurements reveal good cell growth, while immersion investigations show calcification, leading to enhanced osseointegration between the implant and its surrounding tissues. hence, it is an excellent material for dental implants application.

Shear performance of small-rib-height perfobond strip connector groups embedded in UHPC: Experimental investigations and design recommendations

Employing ultra-high-performance concrete (UHPC) with perfobond strip connector (PBL) groups for strengthening steel columns has emerged as a promising solution for the rehabilitation of steel structures. To reduce the cross-sectional area of strengthened members, PBL groups with small rib heights are adopted in thin UHPC layers. However, there are few studies focusing on the shear behaviours of small-rib-height PBL (SRHPBL) groups embedded in UHPC. Therefore, 20 push-out tests were conducted with the variables of SRHPBLs arrangements. The experimental results demonstrated the grouped effect of SRHPBLs embedded in UHPC: (1) the overall shear capacity of twin-rib SRHPBL groups were about 1.67 times higher than that of their single-rib counterparts; (2) the overall shear capacity of SRHPBL groups decreased as the rib spacing of SRHPBLs increased; (3) the overall shear capacity of both the single- and twin-rib SRHPBL groups increased with the row numbers of SRHPBLs, whereas the average shear capacity of an individual SRHPBL increased gradually as the row numbers of SRHPBLs decreased; and (4) the row spacing of SRHPBLs slightly affected the shear performance of single- and twin-rib SRHPBL groups. Finally, theoretical models were developed to predict the shear capacity of SRHPBL groups encased in UHPC.

3D-Printed custom-made hemipelvic endoprosthetic reconstruction following periacetabular tumor resection: utilizing a novel classification system

BackgroundCustomized 3D-printed pelvic implants with a porous structure have revolutionized periacetabular pelvic defect reconstruction after tumor resection, offering improved osteointegration, long-term stability, and anatomical fit. However, the lack of an established classification system hampers implementation and progress.MethodsWe formulated a novel classification system based on pelvic defect morphology and 3D-printed hemipelvis endoprostheses. It integrates surgical approach, osteotomy guide plate and prosthesis design, postoperative rehabilitation plans, and perioperative processes.ResultsRetrospectively analyzing 60 patients (31 males, 29 females), we classified them into Type A (15 patients: Aa = 6, Ab = 9), Type B (27 patients: Ba = 15, Bb = 12), Type C (17 patients). All underwent customized osteotomy guide plate-assisted tumor resection and 3D-printed hemipelvic endoprosthesis reconstruction. Follow-up duration was median 36.5 ± 15.0 months (range, 6 to 74 months). The mean operating time was 430.0 ± 106.7 min, intraoperative blood loss 2018.3 ± 1305.6 ml, transfusion volume 2510.0 ± 1778.1 ml. Complications occurred in 13 patients (21.7%), including poor wound healing (10.0%), deep prosthesis infection (6.7%), hip dislocation (3.3%), screw fracture (1.7%), and interface loosening (1.7%). VAS score improved from 5.5 ± 1.4 to 1.7 ± 1.3, MSTS-93 score from 14.8 ± 2.5 to 23.0 ± 5.6. Implant osseointegration success rate was 98.5% (128/130), with one Type Ba patient experiencing distal prosthesis loosening.ConclusionThe West China classification may supplement the Enneking and Dunham classification, enhancing interdisciplinary communication and surgical outcomes. However, further validation and wider adoption are required to confirm clinical effectiveness.

Morphohistological assessment of osseointegration of dental implants installed during reconstruction of the alveolar part of the mandible by the method of reversible bone block. Experimental research

This article describes an experimental study involving animals, which examines the osseointegration of dental implants installed during the reconstruction of the alveolar part of the mandible by the method of reversible bone block. The protocols of surgical intervention, sampling of material for morphohistological analysis, preparation of biopsy samples for examination, as well as the results of the study are presented.

Effect of Chitosan Irrigant and Lubricating Gel on Bond Strength of Resin Sealer to Radicular Dentin: An In Vitro Study.

The adhesive strength of sealers to dentin is influenced by various factors, and the presence of a smear layer is among the critical variables. Chitosan, known for its dentin compatibility, has previously demonstrated a reduction in dentin change and resin sealer bond strength comparable to ethylenediaminetetraacetic acid (EDTA) when used as an irrigant and final rinse. The study investigates the impact of chitosan, used as both a lubricating gel and final rinse, on the push-out bond strength of resin sealer. Forty single-rooted premolar teeth, each with a fully formed root and a single root canal, were collected post-extraction. During canal preparation, 1 mlsodium hypochlorite (3%) was used for irrigation at every change ofinstrument, followed by applying specific chelating gel and final rinse for each experimental group. The groups included: Group 1 (17% EDTA chelating gel, final rinse with saline), Group 2 (17% EDTA chelating gel, final rinse with 17% EDTA solution), Group 3 (chitosan chelating gel, final rinse with saline solution), and Group 4 (chitosan chelating gel, final rinse with 0.2% chitosan solution), 10 specimens in each group.After obturation, specimens were sealed and incubated for a week at 37°C with 100% humidity. The universal testing machine was used for push-out tests, and specimens were examined using a scanning electron microscope (SEM) to identify various types of bond failure. Among the four groups, Group 2 exhibited the highest mean push-out bond strength (7.33 ± 0.26 MPa), followed by Group 4 (5.33 ± 0.25 MPa), Group 1 (4.61 ± 0.30 MPa), and Group 3 (2.94 ± 0.32 MPa). The variations in bond strength suggest a notable impact of the chelating agents and final rinse solutions on the resin sealer's interaction with dentin. The study concludes that the use of EDTA as both a lubricating gel and a final rinse significantly enhances push-out bond strength, outperforming chitosan in this study. Groups with saline as the final rinse (Group 1 and Group 3) exhibited the least bond strength, highlighting the importance of the final rinse in root canal therapy.

An Innovative Design to Enhance Osteoinductive Efficacy and Biomechanical Behavior of a Titanium Dental Implant.

The present study investigated the in vivo bone-forming efficacy of an innovative titanium (Ti) dental implant combined with a collagen sponge containing recombinant human bone morphogenetic protein-2 (BMP-2) in a pig model. Two different concentrations of BMP-2 (20 and 40 µg/mL) were incorporated into collagen sponges and placed at the bottom of Ti dental implants. The investigated implants were inserted into the edentulous ridge at the canine-premolar regions of Lanyu small-ear pigs, which were then euthanized at weeks 1, 2, 4, 8, and 12 post-implantation. Specimens containing the implants and surrounding bone tissue were collected for histological evaluation of their bone-to-implant contact (BIC) ratios and calculation of maximum torques using removal torque measurement. Analytical results showed that the control and BMP-2-loaded implants presented good implant stability and bone healing for all testing durations. After 1 week of healing, the BMP-2-loaded implants with a concentration of 20 µg/mL exhibited the highest BIC ratios, ranging from 58% to 76%, among all groups (p = 0.034). Additionally, they also possessed the highest removal torque values (50.1 ± 1.3 N-cm) throughout the 8-week healing period. The BMP-2-loaded implants not only displayed excellent in vivo biocompatibility but also presented superior osteoinductive performance. Therefore, these findings demonstrate that BMP-2 delivered through a collagen sponge can potentially enhance the early-stage osseointegration of Ti dental implants.

Microstructural examination of osseointegration using computer microtomography of dental implants installed during reconstruction of the alveolar part of the mandible by the method of reversible bone block. Experimental research

This article describes an experimental study with animal training, which examines the osseointegration of dental implants installed during the reconstruction of the alveolar part of the mandible by the method of reversible bone block. The protocols of surgical intervention, sampling of material for microtomography analysis, as well as the results of the study are presented.

Uncertainty quantification and global sensitivity analysis of bearing capacity of push-out specimen considering randomness in bond-slip behaviour

As an artificial composite material, the uncertainty in mechanical property of concrete significantly impacts the bond-slip behaviour of the shaped steel concrete structure. To investigate the effect of the uncertainty of concrete mechanical properties on the bearing capacity of push-out specimens, based on the data of a small number of push-out test with identical design parameters, the improved Bootstrap method is utilized to execute sample augmentation for the bond stress-slip curves, and the stochastic bond slip constitutive model is established after considering five parameters (K1, …, K5) in the deterministic bond-slip model as random variables. Simultaneously, considering the randomness in elastic modulus of concrete (Ec), uncertainty quantification (UQ) of the bearing capacities of the push-out specimens is conducted using the arbitrary polynomial chaos (aPC) method. Subsequently, the global sensitivity analysis of the ultimate and residual bearing capacities is accomplished through the aPC surrogate model. The results indicate that the probability distribution types of the parameters in the stochastic bond-slip constitutive model can be arbitrary when considering the randomness of concrete material, and the aPC method with at least a third-order expansion is recommended to execute UQ for the push-out test due to the strong nonlinearty between the bearing capacities and the random parameters. The ultimate bearing capacity is primarily affected by the parameter K2, followed by K4, K3, and K5. Whereas the residual bearing capacity is predominantly influenced by the parameter K4, followed by K5, the remaining parameters exhibit negligible influence. In contrast, K1 and Ec have the greatest influence on equivalent plastic strain of the concrete near the loading end of the push-out specimen.

Mechanical behavior of a novel compact steel-UHPC joint for hybrid girder bridges: Experimental and numerical investigation

Ultra-high-performance concrete (UHPC) has recently been applied as an alternative to normal concrete in steel-concrete composite structures. In this paper, a novel compact steel-concrete joint with UHPC grout, which utilizes shear connectors, a bearing plate and a simple I-shaped steel girder, is proposed for long-span railway hybrid girder bridges. To investigate the mechanical behavior and force transfer characteristics of the proposed compact steel-UHPC joint (CSUJ), a model test with reduced scale and push-out tests of its main force transfer components were conducted. The specimens' failure model, load-interface slip, and strain development were compared and discussed in detail. Furthermore, a finite element model of the CSUJ was established to investigate the internal damage evolution and the load transfer path. The test results indicated that the steel-UHPC joint possessed excellent axial stiffness and cracking resistance. The axial stiffness before cracking is 2.6 times that of the steel-concrete joint prototype with C60 concrete grout. Upon loading, the filled-in UHPC of the CSUJ was in elastic compression. In the ultimate limit state, the steel-UHPC joint exhibited great integrity, and the ultimate failure mode of the CSUJ was controlled by the adjacent axially loaded steel beam segment. Results of push-out tests showed that the force transfer component with perfobond leiste (PBL) connectors demonstrated greater ductility than other transfer components. In terms of the force transfer rate and uniformity, the proposed CSUJ provides desired stress distribution and force transfer behavior. The shear connectors, bearing plate, and end face of the I-girder transferred 49%, 35%, and 16% of the total axial force, respectively.

Stress Distribution within the Peri-Implant Bone for Different Implant Materials Obtained by Digital Image Correlation.

Stress distribution and its magnitude during loading heavily influence the osseointegration of dental implants. Currently, no high-resolution, three-dimensional method of directly measuring these biomechanical processes in the peri-implant bone is available. The aim of this study was to measure the influence of different implant materials on stress distribution in the peri-implant bone. Using the three-dimensional ARAMIS camera system, surface strain in the peri-implant bone area was compared under simulated masticatory forces of 300 N in axial and non-axial directions for titanium implants and zirconia implants. The investigated titanium implants led to a more homogeneous stress distribution than the investigated zirconia implants. Non-axial forces led to greater surface strain on the peri-implant bone than axial forces. Thus, the implant material, implant system, and direction of force could have a significant influence on biomechanical processes and osseointegration within the peri-implant bone.

Experimental characterization of bond between concrete and HDG steel tubes for mixed steel-concrete structures

Bond between concrete and reinforcement material is crucial for the structural behaviour and design of reinforced concrete or mixed steel-concrete structures. When considering applications in harsh environments, such as severe marine exposure or submerged conditions, hot-dip galvanized (HDG) steel seems to be a promising solution, as part of new mixed steel-concrete structural systems. Although it is essential to guarantee an effective composite response, the interaction and bond behaviour between materials is not yet sufficiently well understood. This experimental investigation aimed to study the bond behaviour between concrete and HDG steel tubes, including the influence of adopting concrete pin connectors by creating holes in the tube profile, and also the influence of the galvanic surface state. The impact of bond length on the bond behaviour of the galvanized steel tube embedded in different concrete mixtures was analysed. Pushout tests were conducted to obtain the load end versus slip responses, as well as the failure modes. The results showed that the embedment lengths and the concrete compositions had no relevant effect on the overall shape of the pushout experimental responses, with the exception of the specimens that include the concrete pin connector. However, both variables clearly influenced the bond stress, dissipated energy during pushout until failure, and residual pushout force. The addition of the concrete pin significantly improved the adherence mechanism, while the contamination of the galvanic surface showed to significantly reduce the bond strength.

Shelf life effects on the bond strength and microhardness of self-adhesive resin cements.

Among the main advantages of self-adhesive resin cements comprise good aesthetics, strong restoration-tooth bond and biocompatibility. However, some disadvantages, such as high viscosity level, color limitation and short shelf life should be mentioned. Thus, the aim of the current study was to assess bond strength between fiberglass post and root dentin in teeth subjected to self-adhesive resin cements with expired shelf life and hardness. Sixty (60) single-rooted human teeth were sectioned and divided into 2 groups of different cements: U200 3M and MaxCem Elite Kerr. Each group was divided into 3 subgroups, based on self-adhesive resin cements' shelf life, namely: Within the use-time recommended by the manufacturer or no expiration date; 6 months after opening the aluminum blister; 12 months after opening the aluminum blister. Bond strength was measured through push-out test conducted in universal testing machine; fracture pattern was analyzed, and microhardness was investigated through Knoop test, based on hardness readings. Data were subjected to Shapiro-Wilk normality test; nonparametric test was applied to hardness data, whereas parametric test was applied to bond strength data. Hardness data were subjected to Kruskal-Wallis test, whereas bond strength data were subjected to analysis of variance, which was followed by Tukey test; both tests were conducted at 5% significance level (α = 0.05). There was no statistically significant difference in knoop hardness values recorded for the material / time / root thirds combination (p=0.483). There was no statistically significant difference in bond strength values recorded for the Material / Time / Thirds combination (p=0.237). It was possible concluding that shelf life did not influence material's hardness and bond strength. Key words:Dental cements, Resin Cements, Shelf Life of Products.

Comparison of Push-Out Bond Strengths of Different Fiber Post Systems Bonded with Resin Cement

Aim: This study compares the push-out bond strengths of 3 different fiber post systems bonded with resin cement to root canal dentin. Material and Methods: The study used 15 extracted single-rooted mandibular canine teeth. After the endodontic treatment of the teeth, they were randomly divided into three groups to apply different post-systems (n=5). Reforpost glass-fiber, Polydentia glass-fiber, and AAA Transparent fiber post systems were used in this study. The posts have adhered to the root canal with Panavia F2.0. A total of 6 slices of 1 mm thickness in the transversal direction were obtained, two from each of the coronal, middle, and apical sections of the prepared samples. The push-out test was performed from apical to coronal at a 0.5 mm/min speed. ANOVA and Tukey HSD tests were used for statistical analysis (p<0.05). Results: The highest push-out binding values were observed in Polydentia (5.04±0.54); the lowest was seen in Reforpost (1.5±1.03). There was no statistical difference between the push-out binding values of the samples' apical, middle, and coronal regions for Reforpost and Transparent groups. In Polydentia group, the push-out binding values of the coronal region samples were significantly higher than those in the middle region. When the post groups were compared, the difference between the push-out binding values of all groups was statistically significant. Conclusion: The surface properties of the posts can affect the push-out bonding values. Polydentia showed the highest push-out binding values. In addition, the push-out attachment values of the posts may vary in different root canal regions.

Radiographic Evidence of Bone Changes Around Intraosseous Transcutaneous Amputation Prosthesis: An 11-Year Retrospective Cohort Study

ABSTRACT Introduction Percutaneous Osseointegrated Implants (POIs) influence the load transfer path to the host bone. In turn, mechano-regulatory processes (strain adaptive bone remodeling) drive periprosthetic bone changes that influence implant stability and fixation outcome. These bone changes have not yet been reported for the Intraosseous Transcutaneous Amputation Prosthesis (ITAP) clinical trial. Objectives This study will first standardize the zoning and reporting of periprosthetic bone change in POI radiographs. Second, it will retrospectively measure periprosthetic bone change from radiographs of 12 participants with an ITAP up to 11 years. Finally, the results will be qualitatively compared with those from participants with different POI designs. Materials and Methods Twenty participants with unilateral transfemoral amputations received an ITAP in a 2-center UK clinical trial in either 2008/09 or 2013/14. Participant radiographs from one center were available (n = 12) over 11 years and have been collated and processed in a repeatable way. Transverse plane periprosthetic bone change measurements at 3 equidistant points along the implant stem were measured in AP and ML. Results Total median bone growth in AP was double that in ML (57.6 mm and 31.12 mm, respectively). Median lateral and posterior bone change (1.44 mm and 1.09 mm) was greater than median medial and anterior (0.83 mm and −0.005 mm) bone changes, respectively. The greatest change in radial bone growth was observed distally and the least proximally. Conclusions Bone changes were similar to other collared pressfit POIs in the literature. We demonstrate the influence of stem design and mechano-regulatory remodeling in stable fixation; however, additional influences on periprosthetic bone change were inferred from the results and further investigations are necessary. Clinical Relevance To identify ITAP design features and fixations that minimize endosteal resorption, thus promoting implant stability and contributing to clinical guidelines for rehabilitation and future design and fixation choices.

The Effect of Antihypertensive Agents on Dental Implant Stability, Osseointegration and Survival Outcomes: A Systematic Review

Antihypertensive agents are commonly prescribed to manage hypertension and are known to be beneficial for bone formation and remodeling. The aim of this systematic review was to assess the impact that antihypertensive agents have on dental implant stability, osseointegration, and survival outcomes. A review of the literature was conducted using articles from 11 data sources. PRISMA guidelines were followed, and a PICO question was constructed. The search string “Antihypertensive* AND dental implant* AND (osseointegration OR stability OR survival OR success OR failure)” was used for all data sources where possible. The Critical Appraisal Skills Programme (CASP) was used for study appraisal, including the risk of bias. The search resulted in 7726 articles. After selection according to eligibility criteria, seven articles were obtained (one randomized control trial, two prospective cohort studies, three retrospective cohort studies, and a case control study). Five papers investigated the effects of antihypertensive agents on primary stability, but there were discrepancies in the method of assessment. Inhibition of the renin–angiotensin–aldosterone system was linked to higher primary stability. Secondary stability was usually higher than primary stability, but it is unknown if antihypertensive agents caused this. Survival outcomes were increased with certain antihypertensive agents. It is possible that inhibition of the renin–angiotensin–aldosterone system may lead to greater bone mineral density, improved primary stability, and improved survival outcomes although the effects on osseointegration are unknown. However, more research is needed to confirm this theory.

Comparison of push-out bond strength and apical microleakage of different calcium silicate-based cements after using EDTA, chitosan and phytic acid irrigations.

This research was aimed to evaluate push-out bond strength and apical-microleakage after application of three different calcium silicate-based cements with irrigation solutions on simulated immature teeth. 40 maxillary permanent canine teeth were used for push-out bond strength test, and 120 maxillary permanent incisors were used for microleakage evaluation. 120 root slices were divided into four main groups (EDTA, Chitosan, Phytic acid, and Saline) and immersed these solutiouns according to irrigation procedures. Each irrigation group was divided into 3 subgroups (Biodentine, MTA Repair HP, and NeoPUTTY). The prepared teeth were divided into four groups according to irrigation procedure for microleakage test. EDTA irrigation with Biodentine group showed highest push-out bond strength value and saline group with Neoputty showed the lowest push-out bond strength value. The highest microleakage value was seen in saline group with MTA Repair HP, while the lowest microleakage value was observed chitosan with Biodentine group. Chitosan and phytic acid solutions can be recommended as an alternative irrigation solution to 17% EDTA in single-session apexification treatment, since they are non-toxic, naturally occurring materials, effectively remove the smear layer, and have a positive effect on bond strength and apical leakage. RESEARCH HIGHLIGHTS: One of the factors affecting the long-term success of root canal treatment is a hermetic seal. Non-hermetic or inadequate filling triggers a chronic inflammatory reaction in periapical tissues, causing fluids to enter the spaces and negatively affecting the success of the treatment. Therefore, this study will help clinicians choose the right biomaterial and irrigation solution that will affect the success of root canal treatment.

Experimental and theoretical investigations on the static behavior of low aspect ratio shear stud connectors in ultra high performance concrete

In reinforcement project for early-built orthotropic steel bridge decks (OSDs) using ultra high performance concrete (UHPC), low aspect ratio shear stud connectors in UHPC are required. In present study, push-out tests of six static UHPC specimens with and without reinforcement bars were first conducted. The failure modes, load-slip curves and shear capacity of shear stud connectors embedded in UHPC with an aspect ratio of 1.84 were investigated. Subsequently, the experimental results of shear capacity and load-slip curves were compared with the theoretical calculation results. Finally, a new theoretical model of shear stiffness was proposed for low aspect ratio shear studs based on the energy equivalence theory. The experimental results indicated that the failure mode of all specimens was stud shank failure, while the UHPC slabs without reinforcement bars showed extensive cracks. The effect of reinforcement bars on the behavior of shear studs embedded in UHPC slabs can be negligible. The reinforcement bars mainly affected the internal force flow in the UHPC, thus limiting crack initiation and extension. The compressive strength of the UHPC and the weld collar had significant impact on the shear capacity of short studs in the UHPC. In calculating the load-slip curves of short shear stud connectors in UHPC, the theoretical results calculated using the fractional form equations were in better agreement with the experimental results. The proposed theoretical model neglecting the deformation of shear stud in elastic stage can accurately predict the shear stiffness of low aspect ratio shear stud connectors in UHPC.

Effects of Etching Time and Ethanol Wet Bonding on Bond Strength and Metalloproteinase Activity in Radicular Dentin.

(1) Background: The objective of this in vitro study was to evaluate the impact of different etching times and ethanol pre-treatments on the immediate bond strength of a hydrophilic multi-mode universal adhesive (Clearfil Universal Bond Quick, Kuraray, UBQ) and on the consequent gelatinolytic activity of metalloproteinases (MMPs) on radicular dentin. (2) Methods: Sixty single-root teeth were selected and divided into four groups according to the adhesive protocol applied for fiber post cementation: (G1) 15 s H3PO4 application + UBQ; (G2) 30 s H3PO4 application + UBQ; (G3) 15 s H3PO4 application + ethanol pre-treatment + UBQ; (G4) 30 s H3PO4 + ethanol pre-treatment + UBQ. After adhesive procedures, fiber posts were luted into the post space with a dual-curing cement (DC Core, Kuraray) and light-cured for 40 s. To perform the push-out test and nanoleakage analyses for both coronal end apical areas, 1 mm slices were prepared, following a 24 h storage period in artificial saliva. Additionally, an in situ zymographic assay was conducted to explore endogenous MMP activity within the radicular layer. Results were statistically analyzed with ANOVA and Tukey post hoc tests. Statistical significance was set at p < 0.05. (3) Result: ANOVA revealed a statistically significant difference in push-out bond strength related to the pre-treatment variable but did not highlight any significance of etching time. Specimens pre-treated with ethanol wet bond application showed higher bond strength (p < 0.01). In situ zymography quantification analyses revealed that all tested groups, independently of etching time end ethanol pre-treatment, activated MMP gelatinolytic activity. A significant increase in MMP activity was detected for the 30 s etching time. However, ETOH pre-treatment significantly reduced MMP activity within the adhesive interface (p < 0.01). (4) Conclusions: The tested adhesive showed similar results regardless of the etching time protocol. The gelatinolytic activity of MMPs was observed in all the groups. Further investigations and extended follow-ups are required to validate the results of the present study in vivo.

The Effect of Adding Various Antibiotics on the Push-out Bond Strength of a Resin-based Sealer: An In Vitro Study.

This study aimed to compare the bond strength of AH Plus sealer to root canal dentin when used with or without various antibiotics including amoxicillin, clindamycin, and triple antibiotic mixture (TAM). A total of 80 single-rooted extracted human teeth were instrumented and obturated with gutta-percha and four different sealer-antibiotic combinations (n = 20). Group I: AH Plus without any antibiotics, Group II: AH Plus with amoxicillin, Group III: AH Plus with clindamycin, and Group IV: AH Plus with TAM. After seven days, the roots were sectioned perpendicular to their long axis and 1 mm thick slices were obtained from the midroots. The specimens were subjected to a push-out bond strength test and failure modes were also evaluated. Data was analyzed using Kruskal-Wallis and Dunn's post hoc tests. Group IV had significantly higher bond strength compared to other groups (p ≤ 0.05). No significant differences were found between other groups. While the sealer-antibiotic groups predominantly showed cohesive failure modes, the control group displayed both cohesive and mixed failure modes. Within the limitations of this study, the addition of TAM increased the push-out bond strength of AH Plus. Amoxicillin, clindamycin, or TAM can be added to AH Plus for increased antibacterial efficacy without concern about their effects on the bond strength of the sealer. How to cite this article: Adl A, Shojaei NS, Ranjbar N. The Effect of Adding Various Antibiotics on the Push-out Bond Strength of a Resin-based Sealer: An In Vitro Study. J Contemp Dent Pract 2024;25(3):231-235.