Mean Values Of Strength Research Articles

Flexural & Compressive Strength Behaviour of Lowweight Engineered Timber Slab(ETS) composed of crack filler, wood adhesive & Saw dust

This study presents the Compressive & Flexural Strength performance of Low-weight Engineered Timber Slab(ETS) composed of wood adhesive, Saw dust, & crack filler. It provides empirical data on the flexural and compressive properties of engineered timber slab(ETS), which is an element of wood adhesive(WA), sawdust(SD), crack filler(CF). SD gave values of 562.3/m3, 0.67, 39.66%, 2.85, 1.2 and 2.98 for mean bulk density, mean specific gravity, mean water absorption, finess modulus, coefficient of curvature (Cc) and uniformity (Cu). Batching was done by volume by virtue of the low density of the component materials (SD & CF). The component materials were manually mixed. A total of twelve (12) cubes of size 150 x 150 x 150mm, were produced from mix ratios 0.5:0.5:2 & 0.5:0.75:2(WA : CF : SD) for compressive strength test. The above mix ratios were adopted based on the light-weight nature & high rate of water absorption of the component materials. A total of Twenty (20) slabs of size 300 x 300 x 100mm, 300 x 300 x 125mm, 300 x 300 x 150mm, 300 x 300 x 175mm and 300 x 300 x 200mm were cast for flexural strength of slab. Twenty(20) slabs were produced for with slab thickness of 100mm, 125mm, 150mm, 175mm and 200mm using the mix ratios 0.5:0.5:2 & 0.5:0.75:2(WA:CF:SD) respectively. the mean values of the compressive strength, flexural strength and deflection were 14.9MPa & 15.78MPa, 5.06MPa to 5.52MPa and 28.9mm to 86.5mm respectively

Shear bond strength of a composite resin restoration in primary teeth following cavity preparation using laser- an in-vitro study.

To evaluate and compare the shear bond strength of composite resin restorations in primary teeth, following cavity preparation with both traditional dental burs and laser irradiation. One hundred primary molars extracted from the children visiting our department were collected and randomly divided into five groups (A-E) with 20 teeth in each group. In groups A, B, C, D, and E the teeth samples were etched with phosphoric acid, Er; YAG laser followed by acid etching, Er, Cr: YSGG laser followed by acid etching, Er; YAG laser etching only and Er, Cr: YSGG laser etching only, respectively. Following, all the samples were restored with composite resin and subjected to 500 cycles of thermocycling. The shear bond strength of the resin composite was analyzed. The type of fractures was also noted. Data obtained were subjected to statistical analysis. The mean value of shear bond strength of Group A, B, C, D, and E was 17.562 ± 0.810, 15.928 ± 0.415, 14.964 ± 0.566, 11.833 ± 0.533 and 11.187 ± 0.517, respectively. Adhesive failure was most commonly seen in all the groups. The phosphoric acid etching remains a highly effective technique for pre-treating dentin in composite resin restorations. The shear strength of composite resin to the dentin of laser-prepared cavity in primary teeth can be improved by the addition of acid etching.

Impact of different disinfection protocols on the bond strength of NeoMTA 2 bioceramic sealer used as a root canal apical plug (in vitro study)

IntroductionTreatment of an immature permanent tooth required a special disinfection protocol due to the presence of thin radicular walls, which are prone to fracture. Mineral Trioxide Aggregate (MTA) has been proposed as a root repair material for root canal treatment. The aim of this in vitro study was to compare the push-out bond strength of conventional White MTA cements and second generation NeoMTA 2 in imitated immature roots treated with different disinfection protocols, which are 5.25% sodium hypochlorite (NaOCl), followed by 17% ethylenediaminetetraacetic acid (EDTA), and NaOCl, followed by 20% etidronic acid (HEBP).MethodsThe root canals of freshly extracted single-root teeth were manually prepared until 90 K-file to imitate immature roots. Roots were randomly divided into four groups (G) according to the disinfection protocol (n = 15 per group). where G1 (NaOCl + EDTA + White MTA) and G2 (NaOCl + EDTA + NeoMTA 2) While G3 (NaOCl + HEBP + White MTA) and G4 (NaOCl + HEBP + NeoMTA 2) All groups were activated with manual agitation. All specimens were incubated for 48 h. The apical third of each root was perpendicularly sectioned to attain a slice of 3 mm thickness. Push-out bond strength values were assessed using a two-way ANOVA and a Student’s t test.ResultsG3 and G4 that were treated with HEPB showed higher significant push-out bond strength mean values than G1 and G2 treated with an EDTA chelating agent. Irrespective of the chelating agent used, it was found that both NeoMTA 2 and White MTA had no significant influence on push-out bond strength mean values (p ≤ 0.05).ConclusionThe combined use of 5.25% NaOCl and 20% HEBP increased the push-out strength values of both NeoMTA 2 and White MTA, rendering them suitable to be used as an alternative chelating agent to EDTA.

Evaluation of dimensional stability, setting time, tensile strength, and rheological properties of kaolin clay incorporated alginate impression material

This study aims to determine and compare the dimensional stability, setting time, tensile strength, and rheological properties of kaolin clay powder-modified and unmodified alginate impression material. Commercially available alginate-based impression material was considered as a control (C) while experimental groups E-1, E-2, and E-3 were fabricated by adding 2%, 4%, and 8% of kaolin clay powder in the control, respectively. Analytical techniques were used for the characterization of the samples. A tensile strength, rheological property, dimensional stability, and setting time were recorded for control and experimental groups. FTIR analysis confirmed the presence of kaolin clay powder in all experimental groups. SEM showed a round solid structure and irregular shape particle appearance in all experimental groups as well as a control group. The dimensional stability was improved by the addition of kaolin clay powder to the alginate impression material. The percentage dimensional change at 5 min, 6, and 12 h was increased for E3 adding (8% kaolin clay powder) and decreased for the control group. The mean value of tensile strength was highest for E3 followed by E2, E1, and least in control groups. Higher Young’s Modulus and lower deformation values were measured for E3. The mean value of setting time was highest for E3 and the least was in the control group. The results for both setting time and tensile strength were very highly statistically significant (p < 0.001). The mean values of viscoelasticity, flow, and drip test were increased statistically by adding various concentrations of kaolin clay powder to the alginate impression material.

Technical assessment of shear bond strength at ceramo-alloy interface after various surface treatment combinations and application of metal bonding agent.

Bonding between metal and ceramic is one of the most important aspects of a successful prosthesis. Various methods have been recommended for preparing the metal surface to enhance the bond between metal and ceramic including the use of a metal bonding agent. This study aims to evaluate and compare the shear bond strength of the metal-ceramic (M-C) interface after combinations of various surface treatments including the application of a metal bonding agent. 40 Ni-Cr alloy specimens were made and divided into 4 groups of 10 each based on the combination of surface treatments. Sandblasting, surface grinding, and Oxidation heat treatment (OHT) were performed on specimens from Group 1 (Control). In addition, Group 2 specimens received ultrasonic cleaning, Group 3 steam cleaning, and Group 4 metal bonding agent application. Following surface treatments on all specimens, porcelain build-up was performed, and shear bond strength was tested in a Digital Universal testing machine. The statistical tests used were independent t-test and ANOVA. Results revealed that Group 4 specimens had the highest mean value of shear bond strength of 39.087 MPa while Group 3 specimens showed the least mean shear bond strength of 18.154 MPa with highly statistically significant results (p< 0.001). The surface treatments and application of bonding agent to metal prior to porcelain application resulted in increased shear bond strength of the metal-ceramic interface.

Lunate-capitate arthrodesis for scaphoid nonunion: a comparative study

BackgroundScaphoid nonunion advanced collapse (SNAC) injuries are frequently associated with irreversible degenerative wrist arthritic changes that necessitate surgical intervention. Midcarpal fusion remains the mainstay of the management of SNAC II and III injuries. A successful four-corner fusion (4CF) relies on a stable lunate-capitate fusion (LCF). There have been reports of management relying solely on LCF. The outcomes of LC- and 4 C-fusions in SNAC injuries were not widely documented. The objective of this research is to provide valuable insights into the effectiveness of both fusion procedures in the management of SNAC II and III wrist injuries, with a focus on reporting associated complications, functional and radiological outcomes.Patients and methodsThis retrospective study encompassed 65 patients diagnosed with SNAC II and III wrist injuries who underwent limited wrist fusion procedures between 2015 and 2024, with a minimum of 2 years of postoperative follow-up. Exclusion criteria encompassed patients with carpal instability, prior wrist surgical interventions, and scapholunate advanced collapse. Following the fusion procedure performed, patients were stratified into two groups: the LCF group consisting of 31 patients, and the 4CF group comprising 34 patients. Preoperative and intraoperative data were retrieved from the patient’s medical records. At their final follow-up appointments, patients underwent comprehensive radiographic and clinical evaluations. Clinical outcomes including hand grip strength, range of motion, the Disabilities of the Arm, Shoulder, and Hand Score, and the Mayo Modified Wrist Score, were compared between groups. Any associated complications were reported.ResultsThe average healing time was 74.7 ± 15.6 and 72.2 ± 13.2 days for the LCF and 4CF groups, respectively. At the final visit, all patients showed functional improvement relative to their preoperative status, with comparable wrist range of motions observed in both groups. The functional wrist scores were slightly better in the LCF patients (P > 0.05). The average grip strength was significantly greater in the LCF group (P = 0.04), with mean strength values of 86.8% and 82.1% of the contralateral side, for the LCF and 4CF groups, respectively.ConclusionThe LCF is not less efficient than the 4CF in the treatment of SNAC II and III wrist injuries. Through a less time-consuming procedure, LCF can efficiently provide comparable results to 4CF.Level of evidencelevel IV evidence.

Unlocking the Secrets of Residential Construction: Investigating Aggregate Properties for Optimal Building Performance

The objective of this study was to find the strength of aggregates from selected three rivers and suggest to use aggregates for construction from the rivers, where better quality and strong aggregates exists. Aggregates from three selected rivers were tested for, size distribution, aggregate impact value (AIV), Los Angeles abrasion test (LAA). Natural and crushed aggregates were collected and tested for preparing the M20 grade concrete. The mean compressive strength of the concrete made from natural aggregates at 7 and 28 days was fond as 16.72 N/mm2, 16.5N/mm2 and 14.11N/mm2 and 26.22 N/mm2 , 24.29 N/ mm2 and 23.69 N/mm2 for Danda, Jharahi and Boulaha rivers respectively. Similarly, mean compressive strength of concrete made from crushed aggregates at 7 and 28 day was found to be 16.06 N/mm2 , 16.43N/mm2 and 15.16N/mm2 and 26.29 N/mm2, 24.95 N/mm2 and 24.36 N/mm2 for Danda Jharahi and Boulaha rivers, respectively. The null hypothesis (H0) was rejected and alternative hypothesis (H1) was accepted that there exist significant difference in mean value of compressive strength among the river aggregates from selected rivers. However no interaction among the river aggregates was found as Fcalc&lt;Fcrit and Value was found &gt; 0.05 hence null hypothesis was accepted. The higher strength aggregates were found in Danda river whereas lower strength aggregates were found in Boulaha river

Feasibility of prehabilitation for patients awaiting total knee arthroplasty; a pilot study

ObjectiveTo examine the feasibility of conducting a preoperative home-based prehabilitation program for total knee arthroplasty patients at risk for delayed in-hospital recovery, and to explore the pre- and postoperative impact of this program. DesignA retrospective cohort study with matched controls, enabling subgroup analyses. SettingHome-based. SubjectsPatients awaiting primary unilateral total knee arthroplasty between 2019 and 2020, were compared with matched historic cases from 2016 to 2017. Matching criteria were scoring ≤17 points on the De Morton Mobility Index and >12.5 s on the timed-up-and-go test. InterventionSupervised home-based prehabilitation program versus no prehabilitation. OutcomesFeasibility, determined by recruitment rate, adherence, and safety of the program. Preoperative impact, assessed for the intervention group by differences in mean values for aerobic capacity, muscle strength and functional mobility between the first and last sessions. Postoperative impact was defined as the time needed to achieve in-hospital independence of physical function and was measured by the differences in mean values between the intervention and control groups. ResultsRecruitment rate was 71 %; adherence and drop-out rates were 88 % and 12 % respectively. No adverse events were reported. Preoperatively, the intervention group showed significant improvements in aerobic capacity on the 2-min walking test (84.29 m–98.06 m; p = 0.007) and 2-min step test (40.35 steps to 52.95 steps; p = 0.014), muscle strength on the 30 s chair stand test (7.3 stands to 10.1 stands; p = 0.002), and functional mobility as seen in the timed-up-and-go-test (19.52 s–15.85 s; p = 0.031). Postoperatively, the intervention group achieved in-hospital independence of physical function earlier (mean rank 16.11) than the control group (mean rank 24.89; p=<0.01). ConclusionsIt is feasible to conduct a prehabilitation program 4–6 weeks preoperatively, for high-risk patients awaiting total knee arthroplasty. Additionally, the program appears to have a positive impact on physical fitness both pre- and postoperatively.

Effect of Disinfection on Tensile Strength and Rupture Elongation of Maxillofacial Silicone Reinforced with Nano-Filler Particles.

Objectives: Compare the tensile strength and rupture elongation of room temperature vulcanizing silicone (RTV), heat temperature vulcanizing silicone (HTV) and 3% SiO2 reinforced RTV and HTV following disinfection with various agents. Materials and Methods: According to ASTM D412, 384 samples were fabricated using HTV, RTV, RTV and HTV reinforced with 3% SiO2 nanoparticles. The control group received no disinfection treatment, while the other samples were disinfected for 10 minutes using neutral soap, 4% chlorhexidine, and ozone water, three times a day for 60 days. Additionally, accelerated aging was carried out for 252,504,1008 hours. Tensile strength and rupture elongation were assessed using a universal testing machine at 500 mm/min speed, and the mean values were analyzed using two-way ANOVA and Tukey HSD test (P<0.05). Results: The mean value of tensile strength of RTV (2.96 ± 0.41), 3%SiO2 RTV (3.26 ±0.33), HTV (3.30 ±0.36),3% SiO2 HTV (4.07 ±0.85) MPa which was statistically significant for control, neutral soap and 4% chlorhexidine at 252,504 ,1008 hours of aging. (P <0.05). The percentage of elongation of RTV (545 ±29.2),3%SiO2 RTV (617 ±30.5), HTV (735 ±48.7),3% SiO2 HTV (801 ±55.7) which was statically significant for control, neutral soap, 4% chlorhexidine and Ozone water for 252, 504 ,1008 hours of aging. (P <0.05). Conclusion: The HTV silicone showed more tensile strength and rupture elongation compared to HTV, RTV and RTV silicones reinforced with 3% SiO2 nanoparticles. Ozone water disinfection had least effect on tensile strength and rupture elongation of maxillo-facial silicone compared to other disinfectant.

Flexural Properties of Three Novel 3D-Printed Dental Resins Compared to Other Resin-Based Restorative Materials

To evaluate the flexural strength and flexural modulus of three recently introduced 3D-Printed resins and compare them with the flexural properties of other well known, already commercialized, and extensively used resin based dental materials. Three 3D-printed dental resins, a fiber-reinforced epoxy resin, a heat-cured bis-acrylate-based composite resin, two conventional CAD/CAM PMMA, and a graphene-reinforced CAD/CAM PMMA, were selected for this study. Ten prismatic-shaped specimens (2 × 2 × 25 mm) were fabricated for each material (n = 10). All specimens underwent a three-point bending test using a universal testing machine and were loaded until fracture. Flexural strength (MPa) and flexural modulus (MPa) mean values were calculated and compared using the on ranks One-Way ANOVA test. Scanning electron microscope analysis of the 3D-printed resins was performed. Significantly different flexural properties were recorded among the tested materials. The fiber-reinforced epoxy resin exhibited the highest flexural strength (418.0 MPa) while, among the 3D-printed resins, the best flexural strength was achieved by Irix-Max (135.0 MPa). Irix-Plus and Temporis led to the lowest mean flexural strength values (103.9 MPa and 101.3 MPa, respectively) of all the CAD/CAM milled materials, except for the conventional PMMA by Sintodent (88.9 MPa). The fiber-reinforced epoxy resin also showed the highest flexural modulus (14,672.2 MPa), followed by the heat-cured bis-acrylate composite (10,010.1 MPa). All 3D-printed resins had a higher flexural modulus than the conventional PMMA materials. CAD/CAM fiber-reinforced epoxy resin excels in flexural strength, with Irix-Max showing promising flexural properties, which could encourage its use for permanent restorations. Caution is needed with Irix-Plus and Temporis due to their lower flexural strength compared to other traditional materials.

Thermo-mechanically joined hybrids from carbon fiber-reinforced PA12 with die-cast alloy AlSi10Mg: how surface and interlayer design affect shear strength and fracture behavior

ABSTRACT Infrared radiation was used as a tool to heat laser-structured AlSi10Mg for subsequent fusion bonding with thermoplastic carbon fiber-reinforced PA12. When the two adherends are brought into contact, the bond is formed by melting of the surface-near polymer matrix and pressing it into the laser structure of the aluminum alloy. When investigating different fiber volume contents, the amount of fusible material was identified as a key parameter for the achievable bonding strength. Therefore, the best results were achieved with low fiber volume content (25 vol.-%) or under the use of an additional PA12 interlayer. Moreover, the influence of different surface texture parameters was investigated and the aspect ratio between structure depth and width was found to correlate best with the measured shear strengths. Aspect ratios from 0.18 to 1.15 increased the bond strength up to the interlaminar shear strength of the thermoplastic composite. Especially, aspect ratios of 0.61 or greater proved to be very effective, with resulting mean strength values of almost 30 MPa. While even lower ratios allowed higher loads on the joints compared with untreated surfaces, greater aspect ratios show lower bond strengths, as the laser structures were no longer completely filled with fused PA12.

Pattern of strength recovery differences Exist in Adolescent athletes after anterior cruciate ligament reconstruction when using quadriceps versus Hamstring tendon autograft

ObjectivesTo compare the timeline for post-operative quadriceps and hamstrings strength recovery following anterior cruciate ligament reconstruction (ACLR) using either a quadriceps tendon (QT) or hamstring tendon (HT) autograft. MethodsPatients (≤18 years) who underwent ACLR using autograft QT or HT were included. Isokinetic strength was extracted at 3, 6, and 12 months post-operatively. Effects of time and graft type on quadriceps or hamstring limb symmetry index (qLSI/hLSI) was assessed with two-way repeated measures ANOVA. Between group differences at each time point were assessed with unpaired t-tests. Chi-square and Kaplan-Meir analysis analyzed the proportions of subjects able to achieve ≥90% LSI. ResultsA total of 75 subjects (QT n = 38 HT n = 37,15.8 years) were included. There were significant differences in qLSI, with greater symmetry within the HT group at all time points. A higher proportion of subjects with HT grafts were able to achieve ≥90% qLSI within 12 months of surgery (81% vs 45%, p = 0.001). ConclusionCompared to those with HT autografts, adolescents with QT autografts demonstrate a prolonged timeline for quadriceps recovery. While mean strength values above 90% are achieved, a significantly lower percentage of QT patients are able to achieve 90% qLSI by 12 months post-op.

Hip Abductor Muscle Strength Recovery: A Comparison Between Joint Replacement Surgery and Internal Fixation Surgery.

Introduction Proximal femoral fractures are common fractures of the hip that are considered a major healthcare concern globally; these include subtrochanteric, intertrochanteric, and theneck of the femur fractures. Internal fixation surgery and joint replacement surgery are the two most common intervention techniques used to treat these fractures. Consequently, weakness in the hip abductor muscle post-surgery may lead to implant loosening, necessitating revision of the surgery. In light of this, this study aimed to compare hip abductor strength recovery outcomes between joint replacement surgery and internal fixation surgery. Methodology A comparative study was performed over six months at the Department of Orthopaedics and Physiotherapy. Based on the inclusion and exclusion criteria and anticipating potential dropouts, a total of 56 patients were included in thestudy, and their hip abductor strength was measured using a sphygmomanometer. The patients were classified into two groups: Group A or Group B as per the type of hip surgery. Group A included 29 patientswho underwent joint replacement surgeries involving either cemented or uncemented total hip arthroplasty (THA) or hip hemiarthroplasty (HHA). Group B comprised 27 patientswho were operated on using either proximal femoral nail (PFN) or dynamic hip screw (DHS). Results The cohort consisted of 36 males and 20 females, with a mean age of51.71 years. The overall mean value of hip abductor muscle strength at postoperative day (POD) three in the internal fixation group was 65.06 ±5.98, which progressed to 107.51 ±24.76 after six months; in the joint replacement surgery group, it was 70.03 ±12.46 at POD three, which progressed to 113.11 ±21.27 after six months. The age-wise distribution demonstrated that the patients in the age group of 18-50 years demonstrated progressive results: from 65.33 ±4.9 at POD three to 105.95 ±22.71 after six months in the internal fixation group;from 66.82 ±7.72 at POD three to 109.59 ±22.54 after six months in the joint replacement group. Moreover, patients aged above 50 yearsshowed progression from 64.80 ±6.98 at POD three to 103.33 ±27.30 after six months in the internal fixation group, and from 69.58 ±14.75 at POD three to 108.22 ±20.62 after six months in the joint replacement group. Conclusions Our findings revealed thatjoint replacement surgery resulted in greater improvements in the hip abductor muscle strength compared to internal fixation surgery in the immediate postoperative period and during follow-ups. Additionally, younger patients exhibited better strength-related outcomes in comparison to the elderly population regardless of the type of surgery.

The Effect of Different Angled Abutments with Peripheral Groove and Vent Hole on the Retention of Cement Retained Implant – Supported Restorations

Background: The purpose of this study was to analyze the effect of vent hole or peripheral groove on retention of differently angled (15 ° and 30 o) abutments in of cement retained implant supported restorations. Methods: A total of sixty standart implant abutments were used. Abutments were divided into two groups at 15 ° and 30 ° angles on CNC. According to the modification, each group were divided into 3 subgroups; (1) no modifications, (2) with peripheral groove and (3) with vent hole. Sixty metal frameworks were prepared using laser sintering to fit all abutments. All laser sintered frameworks were cemented with eugenol-free provisional cement. Then, all specimens were thermocycled. The frameworks were removed from the abutments by using the universal test machine and the peak removal force was recorded. Statistical analysis were performed with two-way ANOVA, post hoc Tukey’s (HSD) test-adjusted independent samples t-tests. Results: According to the results, there were significant differences between 15 ° and 30 ° groups in terms of retention values (p &amp;lt; 0.001). Additional hole and grooves enhanced retention in both groups. The highest mean value of vertical pull-out strength (185.00 ± 23.08 N) was showed in 15 ° additional grooves group, and the lowest mean value of vertical pull-out strength (27.60 ± 14.84 N) was showed in 30° control group. Means values of additional groove specimens had the highest scores in both groups. In all groups, there were significant differences between all subgroups (p &amp;lt; 0.05). Conclusion: Increased abutment angle decreases retention, while addition of hole and groove increases.

Evaluation of compressive strength, microhardness and solubility of zinc-oxide eugenol cement reinforced with E-glass fibers

BackgroundZinc-oxide eugenol (ZOE) cements are among the most used temporary materials in dentistry. Although ZOE has advantages over other temporary fillers, its mechanical strength is weaker, so researchers are working to improve it. E-glass fibers have emerged as promising reinforcing fibers in recent years due to their strong mechanical behavior, adequate bonding, and acceptable aesthetics.ObjectivesTo evaluate and compare the compressive strength, surface microhardness, and solubility of the ZOE and those reinforced with 10 wt.% E-glass fibers.MethodsA total of 60 ZEO specimens were prepared; 30 specimens were reinforced with 10 wt.% E-glass fibers, considered modified ZOE. The characterization of the E-glass fibers was performed by XRF, SEM, and PSD. The compressive strength, surface microhardness, and solubility were evaluated. Independent sample t-tests were used to statistically assess the data and compare mean values (P ≤ 0.05).ResultsThe results revealed that the modified ZOE showed a significantly higher mean value of compressive strength and surface microhardness while having a significantly lower mean value of solubility compared to unmodified ZOE (P ≤ 0.05).ConclusionThe modified ZOE with 10 wt.% E-glass fibers had the opportunity to be used as permanent filling materials.

Assessment of Isokinetic Trunk Muscle Strength and Fatigue Rate in Individuals after Bariatric Surgery.

Background and Objectives: Lean body mass loss after bariatric surgery (BS) is remarkable, despite an effective long-term mass reduction and significant declines in comorbidities. A person's functional capacity is adversely affected when their skeletal muscle strength declines by up to 30%. This study aimed to assess the isokinetic trunk muscle strength and fatigue rate in individuals after BS. Materials and Methods: This study included fifty-eight patients, both male and female, ranging in age from 19 to 45. Twenty-seven individuals had BS and twenty-seven healthy people served as the control group. The primary outcomes were the measurement of the concentric and eccentric isokinetic muscle strength of the trunk flexor and extensor muscles. An isokinetic dynamometer (Biodex Rehabilitation and Testing System 3) was used for the assessment of the isokinetic muscle strength. Noraxon EMG was used to determine a secondary outcome, which was the median frequency slop (MF/time) and root mean square slop (RMS/time) of the lumbar erector spinea muscle at 50% of the Maximum Voluntary Isometric Contraction (MVIC). Outcome measures were assessed for both groups. Results: Compared to the control group, the bariatric group showed a lower mean value of both concentric and eccentric isokinetic muscle strength for the flexor and extensor trunk muscles (p < 0.05). In terms of the EMG fatigue rate, the RMS slope increased significantly more than that of the control group, while the MF slope decreased (p > 0.05). Conclusions: The current study found that, in comparison to the healthy subjects, the BS group showed reduced levels of fatigue and isokinetic strength in the trunk muscles. Based on these results, it is recommended that individuals who underwent BS take part in tailored rehabilitation programs to avoid potential musculoskeletal issues in the future.

Quadriceps muscle strength and postural balance as intrinsic risk factors of falls in institutionalized healthy older adults: A cross-sectional study in two selected elders’ homes in Colombo, Sri Lanka

Background: Fall is a devastating consequence for elderly people that affects their quality of life. Many stumbles in the elderly are frequently associated with intrinsic risk factors such as muscle strength and balance impairments. The purpose of this study was to determine the relationship between quadriceps muscle strength and postural balance as intrinsic risk factors of falls among healthy elders in two selected elders’ homes in Colombo district, Sri Lanka. Methods: A cross-sectional study was conducted under a non-probability convenient sampling method with 60 elders (34 females &amp; 26 males) who dwelt in the two selected elders’ homes in Colombo district. Fall history was obtained through an interview-administered assessment sheet. A modified sphygmomanometer was used to measure left and right quadriceps muscle strength. The postural balance was assessed using a mini version of the balance evaluation system test (Mini-BEST). Results: Mean age of the study sample was 76.67±6.23 years. The mean and standard deviation values of left quadriceps strength and right quadriceps strength were 138.63 ± 24.35mmHg, 149.90 ± 28.53mmHg respectively. The mean and standard deviation of postural balance was 20.88 ± 2.70. According to Pearson correlation coefficient, a strong positive linear relationship was revealed between right and left quadriceps muscle strength and postural balance. Conclusions: The results of our study revealed a strong positive relationship between quadriceps muscle strength and postural balance among elderly people in two elders’ homes. Therefore, it is recommended that maintaining good quadriceps strength and postural balance are more important to prevent falls in the elderly.

Comparative Evaluation of Bond Strengths Between Dual Cure Resin Cement and Light Cure Resin Cement in Root Surface Indirect Restorations: An In Vitro Analysis Study.

Aim The aim of this study was to evaluate the shear bond strength betweendual cure and light cure resin cements in root surface indirect restorations. Materials and methods Ten recently extracted human teeth were selected. Cylindrical blocks of resin were prepared and bonded nearthe Cemento-Enamel Junction (CEJ) of the prepared teeth to mimic the restoration at the root surface.The samples were randomly luted to the root surface using the light cure (Calibra Veneer, Dentsply Sirona, India) and dual cure (Fusion Ultra D/C, DenPro, USA) formingtwo groups. The bond strength was checked using the INSTRON 3000 device (INSTRON, MA, USA). The point of fracture of the prepared sample from the tooth surface was noted. All readings were tabulated and further statistically analyzed. Results On comparing the two groups, it was found that the light cured resin had a greater mean shear bond strength (57 N) than the dual cure resin cement (41 N).The difference in the mean value of the shear bond strength between two resin cements was found to be statistically not significant according to independent T-test analysis using Levene's Test (P>0.05). Conclusion From the results obtained and within the limits of the study conducted, we can infer that Calibra Veneer is a more viable option for luting to the root surface area. On the other hand, Fusion Ultra Dual cure resin cement seems to have similar results but has a lower bond strength than the other.

Evaluation of flexural strength, impact strength, and surface microhardness of self-cured acrylic resin reinforced with silver-doped carbon nanotubes

BackgroundPoly-methyl methacrylate (PMMA) is a type of polymer mostly used to make denture bases. Self-cured acrylic resin (PMMA) can be used to repair a fractured acrylic denture base; however, even after repair, this area remains vulnerable. Carbon nanotubes (CNTs) could be used as a filler for polymer reinforcement. Furthermore, silver nanoparticles are efficient agents for the prevention of dental biofilm and improving their mechanical properties. The doping of CNTs with silver nanoparticles may lead to a synergistic interaction that is predicted to enhance the mechanical characteristics of the fillers.ObjectivesThe aim of the study was to assess the influnce of manual incorporation of 0.5% weight percent (%wt.) of silver doped carbon nanotubes (Ag-doped CNTs) into commercial self-cured PMMA on its flexural strength, impact strength, and surface microhardness.MethodsIn this investigation, a total of 60 specimens comprised of acrylic resin were employed. They are divided into two main groups: (a) the control group, which was made by using liquid monomer and commercial self-cured PMMA powder; and (b) the modified group, prepared by hand mixing the purchased silver-doped CNTs powder (0.5% wt.) to self-cured PMMA powder (99.5%wt.), and then the blended powder was incorporated into the liquid monomer. Flexural strength, flexural modulus, impact strength, and surface microhardness were evaluated. Independent sample t-tests were used to statistically analyze the data and compare the mean values of flexural strength, flexural modulus, impact strength, and surface microhardness (p-value ≤ 0.05).ResultsThe flexural strength of the modified groups with Ag-doped CNTs (132.4 MPa) was significantly greater than that of the unmodified (control) groups (63.2 MPa). Moreover, the flexural modulus of the modified groups with Ag-doped CNTs (3.067 GPa) was significantly greater than that of the control groups (1.47 GPa). Furthermore, the impact strength of the modified groups with Ag-doped CNTs (11.2 kJ/mm2) was significantly greater than that of the control groups (2.3 kJ/mm2). Furthermore, the microhardness of the modified groups with Ag-doped CNTs (29.7 VHN) was significantly greater than that of the control groups (16.4 VHN), (p-value = 0.0001).ConclusionThe incorporation of 0.5% wt. silver doped CNTs fillers to the self-cured acrylic resin enhanced its flexural strength, flexural modulus, impact strength, and surface microhardness.

The effect of Xylocaine spray on suture material degradation.

To compare the tensile strength of fast absorbable Polyglactin 910 suture material when impregnated with various agents for local anesthesia and to investigate whether the presence of ethanol in Xylocaine spray could explain a potential reduction in tensile strength after use of Xylocaine spray. In all, 120 suture samples of Polyglactin 910 were divided into four groups of 30. These four groups were randomly impregnated with isotonic sodium chloride, isotonic sodium chloride plus Xylocaine spray, isotonic sodium chloride plus Xylocaine gel, or isotonic sodium chloride plus ethanol. After impregnation, the sutures were stored in sealed glass tubes in a heating cabinet at 37°C for 72 h. Thereafter, the tensile strength of these 120 samples was assessed by a universal tensile testing machine. The maximal force needed to break the suture material was recorded in newtons (N). Fast absorbable Polyglactin 910 suture material impregnated with Xylocaine spray or ethanol showed weakened tensile strength (mean values 11.40 and 11.86 N, respectively), whereas the specimens impregnated with Xylocaine gel or sodium chloride retained their tensile strength better (mean values 13.81 and 13.28 N, respectively; mean difference between Xylocaine gel and Xylocaine spray -2.41 N, P < 0.001). In this invitro experiment, ethanol and Xylocaine spray weakened the tensile strength of fast absorbable Polyglactin 910 sutures. Use of Xylocaine spray, which contains ethanol, for local anesthesia might lead to early breakdown of the suture material and wound rupture. The authors suggest caution when using Xylocaine spray in combination with fast absorbable Polyglactin 910 suture.