Post Diameter Research Articles

Effect of fit and self-etching adhesive on fiber post retention in endodontically treated teeth.

Fiber post (FP) reinforced restoration was widespread in endodontically treated teeth, of which the retention was closely related to fit and operation process. However, the question whether the fit and self-etching adhesive (SED) affect the success of FP restoration still remained unclear. This research aimed to assess how the fit and self-etching adhesive (SED) impact the pull-out bond strength (BS) of glass fiber-reinforced composite posts from the root canal dentin. Eighty lower first premolars underwent simulated endodontic treatment, after which their canals were shaped to accommodate a size three RelyX fiber post (FP) (diameter 1.9 mm). They were then divided into 4 equal groups [Unfit post and no SEA (Group UN), Fit post and no SEA (Group FN), Unfit post with SEA (Group UA) and Fit post with SEA (Group FA)] using two different sized FPs and SEA. Cement thickness was acquired by histological analysis and stereomicroscopy. Each sample was tested for pull-out strength through a universal testing machine. Based on the pull-out test, the failure types were observed and scored by visualizing through a stereomicroscope. Group FA demonstrated significantly greater BS compared to Group UN and Group UA, with Group UN showing a statistically significant difference at p< 0.01 and Group UA at p< 0.05. Main failure types in Group FA were Type II, which illustrated that the cement detachment mainly occurred from the post-cement interface. Therefore, Group FA possessed the STRONGEST BS and was most suitable for FP-reinforced crown restorations. Both the fit and SEA enhanced the pull-out BS. The SEA was critical for BS promotion when the mechanical retention was inadequate.

Laser-induced spectral tuning of single quantum dots embedded into microposts cladded with HfO2

Our work investigates the precise tuning of InGaAs quantum dots (QDs) embedded into microposts by leveraging HfO2 crystallization-induced micro-strain via laser annealing. We investigate the efficacy of laser annealing power as a parameter for spectral control, achieving a notable blue shift of QD emissions of up to 5 meV. Through comprehensive Raman thermometry, we reveal consistent dependencies in laser-induced heating relative to micropost diameter, with larger microposts exhibiting superior heat dissipation capabilities and smaller tuning range. For instance, a 5.0 μm micropost demonstrates a maximum local temperature increase of 260 K at 1.82 mW of annealing power, compared to 435 K for a 1.1 μm diameter micropost under the same conditions. By correlating local temperatures derived from the longitudinal optical phonon linewidth of the Raman spectra, with QD emission line blue shift at specific laser powers, the tunability across differing post diameters is studied. Our findings underscore the potential of strain-tuning QDs through laser-induced HfO2 crystallization, offering avenues for scalable resonant single-photon sources applicable in superradiance and multi-photon interference scenarios.

Factors that Influence Growth Rates of Abdominal Aortic Aneurysms. Analysis of a Mexican Cohort.

Abdominal Aortic Aneurysms (AAA) growth remains a process not fully understood. The objective of this study was to analyze risk factors associated with changes in AAA diameter in a Mexican cohort. An observational study in which we analyzed the entirely of patients in which an AAA was reported in a Computed Tomography (CT) study from 2014 to 2021 who had a follow-up CT. We divided them by groups depending on the diagnosis of type 2 diabetic mellitus and pharmacological history (diabetic vs non-diabetic, metformin vs non-metformin intake and statin vs non-statin intake). We compared pre and post follow-up AAA diameters using paired t-tests. A multivariate analysis was performed in order to identify independent variables associated with an increased growth rate. Statistical analysis was performed on Stata 17. During the studied period 72 (39.77%) patients had a follow-up CT. Mean age was 75years (±9.05) and 52 (72.22%) were men. When comparing infra-renal largest diameter through time based on metformin intake, a significant difference was found only in the metformin non-intake group (42.05 ± 12.54 vs45.34 ± 12.06 [P = 0.02]), in contrast the metformin intake group measures were non-significantly different (36.13 ± 7.04 vs 37.00 ± 4.51; P = 0.57) through follow-up. In the multivariate analysis AAA largest diameter at diagnosis correlated with significantly increased growth rate (coeff = 0.06, P < 0.05). AAA diameters appear to change through time in a non-linear pattern influenced by different epidemiological and clinical factors. Metformin intake appears to promote a stability in AAA diameter growth in our studied population.

Experimental study on implant-abutment locking force and abutment subsidence in a pure Morse taper connection implant system.

This test aimed to investigate the factors affecting the locking force between the implant and abutment and the amount of abutment subsidence in pure Morse taper connection implant systems. With reference to the Bicon implant abutment connection design, different types of implant specimens and their corresponding types of abutments were fabricated. The implant-abutment locking taper was uniformly 1.5°. The locking depths were 1.0, 2.0, and 3.0 mm. The diameters of the locking column were 2.5, 3.0, and 3.5 mm. The thicknesses of the outer wall of the implant were 0.15 and 0.30 mm. The loading forces of the testing machine were 200, 300, and 400 N. At least 10 specimens of each group of implant-abutment were used. All specimens were loaded in the same manner using a universal testing machine (finger pressure + specified loading force, five times). The total height of the implant-abutment was measured before finger pressure, after finger pressure, and after the testing machine was loaded for five times to calculate the amount of sinking of the abutment. Finally, the implant and abutment were pulled apart using the universal testing machine, and the subluxation force was observed and recorded. The test loading force, locking depth, and locking post diameter had an effect on the implant-abutment locking force and abutment subsidence. The implant-abutment locking force increased with the increase in the test loading force, locking depth, and locking post diameter (R=0.963, 0.607, and 0.372, respectively), with the test loading force having the most significant effect. Abutment subsidence increased with the increase in test loading force (R=0.645) and decreased with the increase in locking depth and locking post diameter (R=-0.807 and -0.280, respectively), with locking depth having the most significant effect on abutment subsidence. No significant correlation was found between the thickness of the outer wall of the implant and the change in the magnitude of the implant-abutment locking force. However, an increase in the thickness of the outer wall of the implant decreased the amount of abutment subsidence, which was inversely correlated. The locking force of the implant-abutment can be increased by adjusting the design of the pure Morse taper connection implant⁃abutment connection, increasing the locking depth and locking post diameter, and increasing the amount and number of times the abutment is loaded during seating. Problems, such as loosening or detachment of the abutment, can be reduced. The recommended abutment to be loaded should be no less than five times during seating to prevent the abutment from sinking and causing changes in the occlusal relationship in the later stages. Preliminary occlusal adjustments should only be conducted in the early stages of the use of temporary restorations, and final restorations and occlusal adjustments are recommended to be performed after using the abutment for a period of time.

Tuning the Topography of Non‐Wetting Surfaces to Reduce Short‐Term Microbial Contamination Within Hospitals

AbstractMicrobial contamination of hospital surfaces is a major contributor to infectious disease transmission. This work demonstrates that superhydrophobic (Cassie‐Baxter) micro post topographies can significantly reduce cell attachment compared to flat controls. For ordered micro post arrays (post diameters 0.3 to 150 µm), the attachment of four pathogens (Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli, and Candida albicans) from discrete contaminant droplets upon short‐term contact (15 s to 30 min) are assessed. There is a 3‐4‐log decrease in microbial attachment when reducing the micro posts diameters from 150 to 0.3 µm for all strains, with large posts (&gt;20 µm) exhibiting similar attachment rates to flat controls. The critical, maximum feature size to prevent attachment can be tuned depending on the ratio of the cell size to post diameter. Two potential mechanisms are discussed for this size effect. First, application of the random sequential adsorption model shows that this relative post/cell size effect may be due to a reduced probability of attachment, which is theorized to be the dominant mechanism. Alternatively, a physical model is suggested for bacterial cell “pull‐off” due to surface tension forces during droplet dewetting. This work may be important for the design of non‐wetting antimicrobial surfaces within healthcare environments.

Radiographic assessment of dental post and core placement at different educational levels in an undergraduate student clinic: a 4-year retrospective study.

Dental post and core is one of the common procedures performed after endodontic treatment. The aim of this study was to radiographically assess the quality of post and core procedures performed by dental students at different education levels in addition to determining the most critical errors encountered during their clinical practice. A retrospective cross-sectional study design was conducted in the College of Dentistry, Imam Abdulrahman Bin Faisal University. A total of 550 periapical radiographs (PAs) of cemented posts were retrieved from the records of patients treated by dental students. Parameters and guidelines for assessing the quality of post treatment have been determined and statistically analyzed. A P value <0.05 was considered statistically significant. The study included 502 students and most of them were females (66.5%). Data were obtained from 502 patients (62% females) with fiber posts used in 98.2% of the cases. About 50% of the posts were inserted in premolars, 62.9% in the upper arch, and 66.7% were restored with crowns as a final restoration. Regarding the quality of posts, 98.4% showed good preparation quality and 98% showed good radiographic quality. The post diameter was equal to 1/3 of the root diameter in 31.9% of the cases; post length was equal to 2/3 of root length in 5% of the cases and equal to or more than crown height in all cases (100%). Length of the remaining gutta percha (GP) was between 3-5 mm in 38.8%, and there was no gap between the post and remaining GP in 95.6% of the cases. There were no statistically significant differences between dental students at different clinical educational levels regarding the quality of post placement. The quality of post and core procedures performed by students showed acceptable radiographic quality and were within the recommended standards.

Paclitaxel-eluting stents versus paclitaxel-coated balloons in coronary artery disease: a meta-analysis of randomized controlled trials.

The efficacy of drug-coated balloons (DCB) versus drug-eluting stents (DES) for coronary artery disease (CAD) remains inconclusive. Despite paclitaxel's common use in both DES and DCB, there is a lack of meta-analyses comparing paclitaxel-eluting stents (PES) and paclitaxel-coated balloons (PCB). This meta-analysis aimed to evaluate and compare the outcomes of DES and DCB with paclitaxel. A systematic literature search of the Medline and Cochrane databases yielded six randomized controlled trials with 951 patients (1:1 ratio). Primary endpoints were mortality, target lesion vascularization (TLV), myocardial infarction (MI), target vessel revascularization (TVR), and major adverse cardiovascular events (MACEs). Secondary endpoints included in-device binary stenosis, in-segment binary stenosis, late luminal loss (LLL), post-minimal lumen diameter (MLD), and post-diameter stenosis. Within the study populations, the incidence of previous MI was significantly lower in the PES group than in the PCB group (26.70% vs. 39.22%, OR:0.56, 95% CI [0.41-0.76], p=0.0002). The meta-analysis results showed that mortality (OR:1.57, 95% CI [0.67-3.66], p=0.29), TLV (OR:0.74, 95% CI [0.37-1.48], p=0.39), MI (OR:1.76, 95% CI [0.79-3.88], p=0.16), TVR (OR:0.76, 95% CI [0.51-1.12], p=0.16), and MACEs (OR, 1.11; 95% CI [0.48-2.58]; p=0.81) did not exhibit significant differences between the PES and PCB groups in CAD. Furthermore, in stent or in balloon binary stenosis (OR:0.80, 95% CI [0.34-1.87], p=0.60), in segment binary stenosis (OR:1.16, 95% CI [0.48-2.80], p=0.74), LLL (MD:0.03, 95% CI [-0.11 to 0.17], p=0.65), post MLD (MD:0.04, 95% CI [-0.23 to 0.30], p=0.77), and post diameter stenosis (MD:-5.48, 95% CI [-13.88 to 2.92], p=0.20) were similar in both groups. Our comprehensive analysis concludes that both PES and PCB manifest comparable effectiveness and safety in CAD management.

Fracture resistance of endodontically treated teeth, restored with two post-core systems in different post space diameters (in vitro study)

BackgroundFracture resistance of post-core restoration depends on the design of the post, post diameter, post length, the type of adhesive cement used along with material of the core. Despite the different studies concerning the effect of post space diameter on the fracture resistance of endodontically treated teeth, more information regarding fracture resistance and the effect of different post space systems/materials and diameters is required.Aim of the studyThis study aimed to evaluate fracture resistance of endodontically treated teeth, restored with two post-core systems in different post space diameters.Materials and methodsTwenty freshly extracted maxillary central incisors were collected for this study. They were randomly divided into four groups according to intracanal post and its diameter. Group GN (glass-fiber post of 10-mm length and 1.3-mm diameter with composite core), group GW (glass-fiber post of 10-mm length and 1.75-mm diameter with composite core), group ZN (custom-made zirconia one-piece post-core of 10-mm length and 1.3-mm diameter) and group ZW(custom-made zirconia one-piece post-core of 10-mm length and 1.75-mm diameter).Fracture resistance for all samples was evaluated using the universal testing machine under a static load. The data was collected and statistically analyzed using One-Way ANOVA test. Modes of failure were assessed using stereomicroscope for each group.ResultsThe highest mean fracture resistance was recorded in group GW (638.7 ± 285.1 N), followed by group ZW (598.5 ± 127.6 N), then GN group (442.8 ± 65.38 N). The lowest mean fracture resistance was recorded in group ZN (435.3 ± 117.3 N). One-Way ANOVA test revealed that there was no statistically significant difference in fracture resistance values among the groups.ConclusionPost space diameter had an impact over the fracture resistance of endodontically treated teeth. Modulus of elasticity of post material had a major effect on the fracture resistance and mode of failure along with the restorability of the restored tooth. However, there was no statistically significant difference among the tested groups.

Radiographical assessment of post and core placement errors encountered by Saudi dental students at different educational levels

Background: Dental post and core is one of the common procedures performed after endodontic treatment. The aim of this study was to radiographically assess the quality of post and core procedures performed by dental students at different education levels in addition to determining the most critical errors encountered during their clinical practice. Methods: A retrospective cross-sectional study design was conducted in the College of Dentistry, Imam Abdulrahman Bin Faisal University. A total of 550 periapical radiographs (PAs) of cemented posts were retrieved from the records of patients treated by dental students. Parameters and guidelines for assessing the quality of post treatment have been determined and statistically analyzed. A P value &lt;0.05 was considered statistically significant. Results: The study included 502 students and most of them were females (66.5%). Data were obtained from 502 patients (62% females) with fiber posts used in 98.2% of the cases. About 50% of the posts were inserted in premolars, 62.9% in the upper arch, and 66.7% were restored with crowns as a final restoration. Regarding the quality of posts, 98.4% showed good preparation quality and 98% showed good radiographic quality. The post diameter was equal to 1/3 of the root diameter in 31.9% of the cases; post length was equal to 2/3 of root length in 5% of the cases and equal to or more than crown height in all cases (100%). Length of the remaining gutta percha (GP) was between 3–5 mm in 38.8%, and there was no gap between the post and remaining GP in 95.6% of the cases. There were no statistically significant differences between dental students at different clinical educational levels regarding the quality of post placement. Conclusions: The quality of post and core procedures performed by students showed acceptable radiographic quality and were within the recommended standards.

Comparative Stress Analysis of Custom-Made PEEK Dental Post-Cores versus Conventional Post-Cores in Incisor Restorations: A Finite Element Study.

BACKGROUND We conducted a finite element analysis to evaluate stress levels in incisor teeth restored with custom polyetheretherketone (PEEK) dental post-cores compared to conventional post-cores. MATERIAL AND METHODS Using micro-computed tomography (μCT) imaging data, a 3D model of a maxillary incisor was created. For each material type, 3D mesh models were developed via specialized software. Two post diameters, 2.5 mm and 3.5 mm, were considered. Five different post materials were examined: Unfilled polyetheretherketone (Group UP); Glass fiber-reinforced polyetheretherketone (Group GP); Carbon fiber-reinforced polyetheretherketone (Group CP); Metal (Group M); and Zirconia ceramic (Group Z). Each model underwent finite element analysis, after which the von Mises equivalent stress values were determined. RESULTS For models involving both wide and narrow diameter posts across the crown, crown cement, post cement, and dentin, PEEK posts (Group UP, GP, and CP) exhibited higher von Mises stress values than Groups Z and M. However, the reverse trend was noticed in the post model itself. In the post cement model, stress values appeared similar only for the narrow-diameter post groups. Notably, results for Groups Z and M were largely consistent with each other. CONCLUSIONS PEEK posts, which have a lower modulus of elasticity, demonstrated different stress values when contrasted with zirconia and metal posts. As the post diameter expanded, the residual dentin decreased, influencing the stress values among various materials. Further in vitro and clinical examinations are essential to comprehensively understand PEEK posts.

Engineering Substrate-Mediated Localized Surface Plasmons in Gold Nanodiscs

A variety of nanostructures capable of generating strong local electromagnetic fields (hot spots) in interaction with radiation have been under intensive investigation towards plasmonic applications in surface-enhanced Raman scattering (SERS), biosensing, broadband absorbers, thermophotovoltaics, photocatalysis, etc. In many cases, these nanostructures are formed on a surface or embedded into a near-surface layer of the dielectric substrate, making some part of the field dissipate into the bulk and not contribute to the desired plasmonic functionality. To reduce such losses, the interface between the metallic nanostructures and the dielectric environment should be engineered. In the current work, Au nanodiscs are fabricated on Si posts of very small diameter (pin-shaped structures), enabling them to decouple the strong optical near fields localized at the nanodiscs from the bulk Si substrate. The Si post diameter is optimized by adjusting the gas flow rates in reactive-ion etching, resulting in a minimum post diameter of 20 nm at the nanodisc interface. The effect of this diameter on the localized surface plasmon resonance of the nanodisc is investigated with linear optical spectroscopic measurements, where a significant spectral blue shift of the resonance band is noticed compared to similar discs formed on bulk Si surface. The experimental results are compared with modelling where a 3-fold increase in the electric field enhancement is demonstrated. The fabricated pin-shaped nanostructures are tested in SERS measurements showing a significant increase in the enhancement factor in the order of 106. Thus, this work suggests a way of engineering 3D morphology to tune the substrate influence on the plasmonic properties of nanostructures and to develop efficient nanofabrication technologies.

Bond strength of various post-core restorations with different lengths and diameters following cycle loading

PurposeThis in vitro study aims to evaluate the bonding strengths of Polyether ether ketone (PEEK), Polyether ketone (PEKK), Fiber, and Zirconia (ZrO2) post-core restorations with posts in different diameter and length following chewing simulator. Materials and methodsEndodontic treatment was performed on 256 intact maxillary central teeth. The test specimens were prepared in four groups according to the types of materials: Glass fiber post-composite core (FB-n:64), Zirconia post-core (Zr-n:64), PEEK post-core (PE-n:64), and PEKK post-core (PK-n:64). The groups were divided into four subgroups according to diameter and length (n:16): Group 1: 10 mm length 1.75 mm diameter, Group 2: 10 mm length 1.5 mm diameter, Group 3: 7 mm length 1.75 mm diameter, Group 4: 7 mm length 1.5 mm diameter. Custom PEKK, PEEK, Zirconia post-cores, and Zirconia crowns were milled on the CAD/CAM. The post-cores and crowns were cemented to the teeth with dual-cure resin cement. After that, all subgroups were divided into control and cyclic loading groups. During the cycling, the control test group was kept in distilled water at 37±1oC before the push-out test. Half of the specimens were loaded with 250,000 cycles and 50 N with a chewing simulator. All test specimens had 1.5 mm sections taken from their roots. Then, the push-out test was applied to these sections for bond strength. Data were analyzed by Mann-Whitney U test, Shapiro-Wilk, Kruskal-Wallis's test, and Chi-Square. The statistical significance level was determined as 0.05. ResultsThe bond strength of all test groups decreased after the cycling loading. The bond strength values of zirconia posts showed a statistically significant difference (p < 0.05). The 10 mm length 1.75 mm diameter posts made of Zirconium had the highest bond strength observed in all control and cyclic loading groups of test specimens (9.74 MPa-6.25 MPa). The PEEK test specimens with a 7 mm length and 1.75 mm diameter showed the weakest bond strength in all control and cyclic loading groups (5.44 MPa-3.37 MPa). The average of the cervical region's bond strength values was statistically significantly higher than the apical region (p < 0.05). ConclusionWithin the limitations of this study, one-piece custom-milled Zirconia post-cores appear promising, as they perform well under functional forces, especially in the anterior region. In addition, custom-milled PEKK post-cores might be considered a suitable alternative to prefabricated fiber-reinforced posts.

Transmission of radiant light energy through the sides of fiber posts.

Resin cements are light polymerized, but the light may not reach all areas of root canals. The purpose of this study was to determine the best predictor of transmitted light radiant exposure (TLRE) from posts' sides. Fiber posts were placed in a custom-made apparatus and advanced by 1-mm increments. The LED curing probe tip was activated for 40 s on the coronal end of the post. The TLRE was measured with an LED radiometer detector positioned on the side of the post exposed by an opening in the apparatus. Hierarchical multiple linear regression analysis was performed. Post system explained an additional 23.62% of the variation in TRLE. Adding actual post diameter explained an additional 62.64% of the variation in TRLE. While adding post length explained an additional 0.67%. Changing post system from FiberKleer to Postec Plus will decrease the mean value of TRLE by 4.90 units on average. Also, a one-unit increase of actual post diameter and length will decrease the value of TRLE by 44.96 and 0.44 units respectively. The TLRE ranged from 46 to 290 mJ/cm2 , which was between 0.73% and 6.63% of the original emanating light. The changes in post system, posts' diameter and length can be used to predict the unit changes in TLRE on the side of a translucent fiber post. Emanating radiant exposure from the side of the post was lower than 6.63% of the exposure entering the post. Fiber post diameter and length and post system can influence light radiant exposure transmitted from posts' sides, transmitting minimal radiant exposure, which can be increased by increasing curing duration.

Optimal post height and diameter in preformed zirconia crown restoration on 3D-printed primary incisors.

In this in vitro study, fracture resistance was evaluated according to the post-diameter and -length in zirconia crown restorations on three-dimensional printed primary incisors undergone pulpectomy. One hundred-and-sixty primary incisor abutments were used which were artificially fabricated through 3D-printing. Each group was divided into two subgroups based on the zirconia post-diameter (1.5 mm and 2.0 mm) employed for post setting after pulpectomy. Furthermore, each group was divided into four subgroups based on the zirconia post-height (3.0, 4.0, 5.0 and 6.0 mm). Zirconia post setting was made by applying flowable resin after filling the pulp cavity with calcium hydroxide up to 3.0 mm below cemento-enamel junction (CEJ). Finally, a preformed zirconia crown of size #1 was cemented to the abutment through resin cement. A compressive load was applied to the middle palatal surface of incisors restored with zirconia crowns by using a universal testing machine at 145° angle which is the normal interincisal angle of children. The root fracture specimens were excluded and the samples fractured within crown and core parts were included in the final fracture resistance analysis. The group with 1.5-mm post-diameter and 5.0-mm post-height had the highest fracture resistance strength (130.63 ± 55.75 N) under masticatory pressure condition. Fracture resistance was statistically greater in 5.0-mm than in 4.0-mm and 3.0-mm post-height groups for 1.5-mm post-diameter subgroup. Moreover, 5.0-mm post-height subgroup had a statistically greater fracture resistance than that of 3.0-mm post-height subgroup for 2.0-mm post-diameter group. The 2.0-mm post-diameter subgroup had a statistically greater fracture resistance than that of 1.5-mm post-diameter subgroup for 3.0-mm and 4.0-mm post-heights. If zirconia post incorporation is required for deciduous incisor restoration, a post-length equal to facial CEJ level is recommended for gaining additional retention against masticatory pressure.

Effect of Er:YAG laser on removal of fibre posts from root canal.

The aim of this study was to evaluate the efficiency of Er:YAG laser in translucent fibre post removal. 60 human single-rooted anterior teeth were divided into three groups (n=20) according to post diameters (Exacto1-E1, Exacto2-E2, Exacto3-E3) and subdivided according to laser application. Fibre posts were cemented to endodontically treated teeth, and the specimens were sliced with a thickness of 1.0 ± 0.2 mm. Er:YAG laser was applied and the push out bond strength test was performed. Two-way analysis of variance was used to perform the statistical analysis. Push out bond strengths at apical area were significantly lower in all test groups (p < 0.05). Laser application caused increase in all radicular thirds, but it was significant for E1 and E3 groups. Laser application to the post-dentine interface enhances the connection between post and dentine.

PENGARUH PEMBERIAN PUPUK KOMPOS TERHADAP PERTUMBUHAN BIBIT OCTOMELES SUMATRANA MIQ. PADA MEDIA TANAH BEKAS TAMBANG

Mining activities result on environmental degradation and finally on ecosystem damage. Efforts to restore post mining land productivity with compost aplication. Compost contains macro and micro nutrients can increasing physical, chemical and biological soil properties. This study aims to know the effect of compost fertilizer on the growth of O. sumatrana seedlings in post-mining soil.There were two factors in this study: AMF inoculation and compost treatment. Compost application increased height post mining soil (2 MST, 4 MST, 6 MST, 8 MST dan 10 MST), diameter (4 MST, 6 MST, 8 MST dan 10 MST), total biomass, roots biomass, and sprout biomass of O. sumatrana

The impact of provisional intraradicular retainers cementation with temporary methacrylate-based resin in the bond strength of glass fiber posts to root dentin

Chemical composition of temporary cements interferes in the bond strength and quality of the bond interface of glass fiber posts to root dentin. The aim of the present study was to evaluate the influence of different temporary cements on the bond strength of fiberglass posts and resin cement. Thirty-two maxillary central incisor roots were standardized at 15 mm length. The root canals were prepared with Reciproc R50 and filled with a R50 single cone and AH Plus. Ten mm of filling material was removed with a heated Schilder condenser, leaving 5 mm of apical filling material. The roots were randomly distributed into 4 groups (n = 8). In the control group, the root canal was prepared with a standard drill according to the post diameter (DC #1, FGM, Joinville, Brazil), irrigated with 5 mL of distilled water and immediately received the fiberglass post cemented with self-adhesive resin cement. For the other groups, cores were made with temporary intraradicular retainers cemented with different temporary cements: methacrylate-based resin (Bifix Temp - Voco), calcium hydroxide-based (Provicol - Voco) and zinc oxide-based – eugenol-free (Relyx Temp NE - 3M). After 7 days, mechanical removal of the temporary retainers, preparation, irrigation of the root canal and cementation of the fiberglass post were performed, following the same protocol that had been performed in the control group. The roots were sectioned to obtain 3 slices per root third. The most cervical section of each third was used for the push-out test and failure pattern analysis, while the most apical section was subjected to analysis of the adhesive interface by scanning electron microscopy (SEM). The BS data were compared between groups using the two-way ANOVA and Tukey post-test. The failure pattern results were expressed in percentage and compared between groups using the chi-square test and the material adaptation data at the bond interface were evaluated using the Kruskal-Wallis and Dwass-Steel-Critchlow-Fligner tests. The results showed higher BS in the cervical third, with a higher value in the control group (10.8 ± 0.94) and Bifix Temp group (9.78 ± 0.71), with no statistically significant difference between these groups (P > .05). The middle and apical thirds showed no statistically significant difference (P > .05). As regards the type of failure, a higher percentage of mixed adhesive failures was observed for all groups. Analysis of the adhesive interface by SEM showed that the temporary cement Bifix Temp showed greater adaptation at the bond interface. It was concluded that the methacrylate-based resin temporary cement showed the highest bond strength values and best adaptation to root dentin than the zinc oxide-based and calcium hydroxide-based temporary cements.

Fracture resistance of endodontically treated teeth and restored with different fiber posts in distinct diameters

Objective: The aim of this in vitro study was to evaluate the fracture resistance of endodontically treated teeth restored with different intraradicular posts (carbon fibers, glass, or quartz) with varying post diameters (narrow, medium, or large). Methodology: One hundred and twenty bovine incisors were endodontically treated and the post space was prepared. The teeth were classified according to distinct diameters post space [Narrow (0.91-1.49mm), Medium (1.5-2.08mm), Large (2.09mm-2.67mm)] and randomly allocated to four restorative treatments: control (CO) - without post; and glass fiber (GF), carbon (CF) or quartz (QF) posts. The posts were cemented with dual-cure resin cement (Duo Link, Bisco, Schaumburg, United States) and the coronary portion was reconstructed with dual-cure resin composite (Bis-Core, Bisco, Schaumburg, United States). Fracture resistance values (N) were analyzed by two-way ANOVA and Bonferroni test (α=0.05). Results: The carbon fiber post (CF) was mechanical behavior similar to the other evaluated posts, regardless of the diameter. The control group (without post) showed the highest values of fracture resistance (1013.8 - 1127.2 N) in relation to the groups with the different evaluated posts (236.1 - 615.1 N). Within the same material, the diameter influenced the fracture strength only of the quartz fiber post, with the highest values for diameter large. Conclusion: A larger diameter only gives greater fracture resistance for QF; CF posts have similar resistance to other posts, regardless of diameter; and for large diameter, the type of post used does not differ in fracture resistance.

Radiographic Analysis of Posts Performed by Undergraduate Dental Students: A Cross-Sectional Study.

IntroductionPost and core restorations for endodontically treated teeth must meet certain prosthetic criteria to ensure the success of the final restoration. The aim of this study is to evaluate the quality of posts performed by dental students at King Abdulaziz University Dental Hospital (KAUDH), Jeddah, Saudi Arabia, utilizing periapical radiographs and whether the prosthetic criteria were strictly met by students.Materials and MethodsThis cross-sectional study included 661 digital periapical radiographs of posts performed by 6th-year dental students from September 2018 to April 2019. The assessment included the following factors: patient’s age, patient’s gender, tooth type, and arch. Post-related factors including post type, shape, diameter, length, and status of the remaining gutta percha were also evaluated. Statistical analysis was performed using SPSS. Descriptive statistics were generated, and the association between different variables was determined using chi-square test at p<0.05.ResultsPosts were used to restore maxillary teeth (67%), and were particularly placed in premolars (44%). The majority of used posts were prefabricated tapered fiber posts (90%). The results were as follows: post diameter equal to one-third of root diameter, 50% met criterion; post length equal to two-thirds of root length, 33%; post length equal to or more than crown height, 93%; absence of space between gutta percha (GP) and post, 74%; and length of the remaining GP equal to 3–5 mm, 68%. Overall, 11% of the posts met all the ideal prosthetics criteria.ConclusionMost qualities of post and core restorations that were radiographically assessed were found to be acceptable and within the recommended prosthodontic criteria.

Divisions in a Fibrillar Adhesive Increase the Adhesive Strength.

To realize the potential of bioinspired fibrillar adhesive applications ranging from biomedical devices to robotic grippers, there has been a significant effort to improve their adhesive strength and understanding of the underlying adhesion and detachment mechanisms. These efforts include changes to the backing layer, which connects the roots of all of the pillars in the fibrillar adhesive. However, previous approaches such as thickness or elastic modulus changes are selectively advantageous to the adhesive strength depending on the substrate condition because of the trade-off between conformity to misaligned/rough surfaces and increased interfacial stress concentrations. In this work, we explore mechanical divisions (cuts) in the backing layer as a new approach to improve the adhesive strength without this trade-off. We combine experiments and finite element analysis (FEA) to study the effect of the divisions, which decouples the mechanical interaction between the pillars on the divided layers, and show that the adhesive strength can be improved regardless of the substrate condition. Tensile adhesion experiments show increased adhesive strength with cuts to a micropost array (150 μm diameter posts) by approximately 25% for 4 divisions. In situ imaging of pillar detachment shows a transition of the detachment process from a peel-like detachment to a random detachment sequence. FEA simulations of the detachment process suggest that the increased strength may originate from a simultaneous enhancement of the load distribution between the pillars and the compliance of the backing layer.