scholarly journals Influence of Dental Glass Fibers and Orthopedic Mesh on the Failure Loads of Polymethyl Methacrylate Denture Base Resin

Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2793
Author(s):  
Muhammad H. Rana ◽  
Sharaz Shaik ◽  
Mohammad S. Hameed ◽  
Samar Al-Saleh ◽  
Eman M. AlHamdan ◽  
...  
Keyword(s):  
Polymethyl Methacrylate ◽  
Glass Fibers ◽  
Testing Machine ◽  
Fracture Load ◽  
Denture Base ◽  
Group 4 ◽  
Failure Loads ◽  
Group 2 ◽  
Contrast Group ◽  
Group 1

The aim of the present study was to evaluate the fracture loads of polymethyl methacrylate (PMMA) complete denture bases reinforced with glass-fiber mesh and orthopedic casting tape (OCT) in comparison to conventional PMMA dentures under artificial aging. Dental fiberglass framework (Group 1) and OCT (Group 2 and 3) reinforced PMMA acrylic dentures were fabricated on the edentulous ridge. Ten PMMA dentures without reinforcement (Group 4) were included as controls. All specimens were placed in a chewing simulator chamber, and fatigue load was applied. To assess the fracture loads, static loads with a universal testing machine were applied. Fractured specimens in each group were evaluated under a scanning electron microscope. The data were statistically analyzed employing analysis of variance and Tukey post-hoc test. The association of denture weight and thickness on fracture load was assessed using Pearson and Spearman correlations. Dental fiberglass (Group 1) displayed the highest fracture load (692.33 ± 751.41 N), and Group 4 (control) exhibited the lowest fracture loads (281.41 ± 302.51 N). Dentures reinforced with fiberglass mesh framework exhibited intact fractures. In contrast, Group 2 and 3 specimens using OCT demonstrated ditching fractures. It was observed that the thickness and weight of all the reinforced specimens influenced the load required to fracture the dentures (p < 0.001). Denture specimens strengthened with OCT (Groups 2 and 3) exhibited failure loads lower than dental fiberglass (Group 1) specimens but higher than unreinforced controls.

Effect of Bidirectional Insertion of External Skeletal Fixation Pins on Axial Pullout Strength in Canine Cadaveric Bone

2021 ◽  
Author(s):  
Jane Park ◽  
Danielle Dugat ◽  
Mark Rochat ◽  
Hall Griffin ◽  
Mark E. Payton
Keyword(s):  
Testing Machine ◽  
Fluoroscopic Guidance ◽  
Pullout Strength ◽  
Group 4 ◽  
Group 12 ◽  
Group 3 ◽  
Group 2 ◽  
Depth Gauge ◽  
Position Group ◽  
Group 1

Abstract Objective The aim of this study was to evaluate the effect of bidirectional insertion on axial pullout strength of tapered run out (TRO), traditional negative profile (TNP) and positive profile (PP) pins. Study Design Cadaveric adult canine tibiae were harvested. Tapered run out pins (Group 1) were inserted unidirectionally to the desired position; bidirectionally past the desired position, then withdrawn to the desired position (Group 2); and bidirectionally as described for Group 2, repeated twice (Group 3). Traditional negative profile pins (Group 4–6) and PP pins (Group 9–11) were placed in the same manner. Tapered run out (Group 7), TNP (Group 8) and PP pins (Group 12) were driven unidirectionally such that the shaft of the pin violated the cis-cortex. A servohydraulic testing machine extracted the pins and measured axial peak pullout strength. Results Positive profile pins had significantly greater pullout strength than TRO and TNP pins placed unidirectionally to the desired position. Method of insertion had no effect on peak pullout strength of TNP pins. TRO and PP pins inserted unidirectionally to the desired position had significantly greater peak pullout strengths than insertion bidirectionally or if the shaft of the pin violated the cis-cortex. Conclusion The authors recommend that pins used for external skeletal fixation should be placed unidirectionally to the desired position with fluoroscopic guidance, intra-operative depth gauge measurements or measurements from preoperative radiographs. Repositioning pins results in loss of peak pullout strength with TRO and PP pins.

Bond Integrity of Titanium Surface to Resin Cement After Conditioning with Different Photobiomodulataion Therapy (PBT)

2021 ◽  
Vol 11 (5) ◽  
pp. 970-975
Author(s):  
Khold Al Ahdal ◽  
Laila Al Deeb ◽  
Mohammed S. Bin-Shuwaish ◽  
Rana S. Al-Hamdan ◽  
Modhi Al Deeb ◽  
...  
Keyword(s):  
Titanium Alloy ◽  
Testing Machine ◽  
Resin Cement ◽  
Control Group ◽  
Sem Images ◽  
Group 4 ◽  
Modes Of Failure ◽  
Group 5 ◽  
Group 2 ◽  
Group 1

The aim of the present study was to evaluate the efficacy of interfacial bonding between resin cement and titanium alloy conditioned with different Photobiomodulataion Therapy (PBT) in comparison with conventional regimes. Seventy-five samples of titanium bar were segmented polished; and based on conditioning regime divided into five groups (15 each specimens). Group 1: No treatment (control), Group 2: Sand blasting with 120 µm Al2O3, Group 3: Er,Cr:YSGG (ECL), Group 4: Er:YAG laser (EYL), Group 5: Nd:YAG laser (NYL). After different conditioning regimes, resin cement was mixed and applied. All specimens were thermocycled for 500 cycles and positioned on universal testing machine for shear bond strength testing. Modes of failure was assessed by a single examiner using stereomicroscope at 40× magnification. Three pairs of specimens in each group were sputter coated and scanning electron microscope (SEM) images were taken at 1000× magnification using 20 Kv. The highest SBS values were observed in group 2 (14.25±2.29 MPa) and the lowest bond values were displayed in group 1 (6.98 ±0.59 MPa). Titanium alloy abutments conditioned with different laser prototypes ECL (11.22±1.40 MPa), EYL (9.29±1.22 MPa) and NYL (9.12 ±1.84 MPa) exhibited comparable SBS (p > 0.05). Adhesive failures were primarily dominant among all experimental groups. Photo-biomodulation in the form of ECL lasers has the potential to be used as a supplement to sandblasting procedure in conditioning of cement retained titanium alloy implant abutments.

Assessing Burnout in Subgroups of Athletes Based on Gratitude and Perceived Coach-Athlete Relationship

2021 ◽  
pp. 003329412199183
Author(s):  
Mariya A. Yukhymenko-Lescroart ◽  
Jeffrey B. Ruser ◽  
Nicole T. Gabana ◽  
Jenelle N. Gilbert
Keyword(s):  
Protective Role ◽  
Three Dimensions ◽  
Intercollegiate Athletes ◽  
Male Athletes ◽  
Group 4 ◽  
Athlete Burnout ◽  
Group 3 ◽  
Group 2 ◽  
Contrast Group ◽  
Group 1

The purpose of this study was to examine distinct groups of athletes based on their gratitude and coach-athlete relationships (CAR) and to compare the groups on three dimensions of athlete burnout: sense of reduced accomplishment, emotional and physical exhaustion, and sport devaluation. Types of gratitude measured included general trait gratitude, general state gratitude, and sport state gratitude. Cluster analysis with 576 intercollegiate athletes showed four distinct groups: “ungrateful in life and sport, and disconnected from the coach” (Group 1), “highly grateful in life and sport, and well-connected with the coach” (Group 2), “generally less grateful in life, but connected with the coach” (Group 3), and “generally grateful in life, but disconnected from the coach” (Group 4). Group 1 reported the highest levels of burnout. In contrast, Group 2 reported the lowest levels of burnout. Athletes in Groups 3 and 4 (which were similar on sport state gratitude, but differed on other indicators) reported moderate levels of burnout, but Group 4 athletes were more burned out than Group 3 athletes. Specifically, both groups reported similar levels of devaluation; yet, Group 4 scored higher on reduced sense of accomplishment and emotional/physical exhaustion than Group 3. Examination of group composition revealed that male athletes were overrepresented in Group 2 and underrepresented in Group 4, and Group 1 athletes tended to identify as non-religious. Taken together, findings point to the protective role that gratitude and a positive CAR may play in athlete burnout prevention.

scholarly journals Comparison of Shear Bond Strength of Four Types of Orthodontic Brackets with Different Base Technologies

2017 ◽  
Vol 7 ◽  
pp. 273-278
Author(s):  
Gaurang H. Chaudhary ◽  
Gianina Salton Mattevi ◽  
Peter Thiuri Gakunga
Keyword(s):  
Bond Strength ◽  
Shear Bond Strength ◽  
Testing Machine ◽  
Group 4 ◽  
Significant Difference ◽  
Acid Etch ◽  
Group 3 ◽  
The Difference ◽  
Group 2 ◽  
Group 1

Objectives The aim of this study was to compare the shear bond strength (SBS) of brackets systems with four different base technologies. Materials and Methods Maxillary first premolars were randomly divided into four groups of thirty specimens each: (1) Master Series™ conventional twin, (2) T3™ self-ligating, (3) Victory series™ conventional twin, and (4) H4™ self-ligating brackets. Maxillary first premolars were bracketed using an acid-etch composite system, and the SBS measured using an Instron Universal Testing Machine at a crosshead speed of 2 mm/min. The ANOVA and Tukey’s multiple comparison tests were performed with significance predetermined at P ≤ 0.05. Results The overall mean bond strengths were 8.49 ± 2.93, 10.85 ± 3.34, 9.42 ± 2.97, and 9.73 ± 2.62 for the Groups 1, 2, 3, and 4 brackets, respectively. One-way ANOVA test gave an F = 3.182 with a P = 0.026. The Group 1 and Group 2 were observed to have statistically significant difference with a P = 0.014. Conclusions The T3 self-ligating one-piece design with microetched Quadra Grip™ base brackets had the highest bond strength. The SBS difference between Group 2, Group 3, and Group 4 was not significant, but the difference between Group 2 and Group 1 was statistically significant.

scholarly journals Compressive Resistance of Abutments with Different Diameters and Transmucosal Heights in Morse-Taper Implants

2015 ◽  
Vol 26 (2) ◽  
pp. 156-159 ◽  
Author(s):  
Ricardo Lillo ◽  
Carlos Parra ◽  
Ramón Fuentes ◽  
Eduardo Borie ◽  
Wilfried Engelke ◽  
...  
Keyword(s):  
Mechanical Behavior ◽  
Testing Machine ◽  
Compressive Loading ◽  
Loading Test ◽  
Group 4 ◽  
Group 3 ◽  
Group 2 ◽  
Different Diameters ◽  
Compressive Resistance ◽  
Group 1

The aim of this study was to evaluate the compressive resistance under oblique loads of abutments with two different diameters and transmucosal heights used for cement-retained implant-supported prostheses in Morse-taper implants. Forty Morse-taper implants were divided into four groups with different abutment sizes for cement-retained prostheses in order to perform the compressive test. The groups were divided by abutment diameter and transmucosal height as follows: Group 1: 4.5 x 2.5 mm; Group 2: 4.5 x 3.5 mm; Group 3: 3.3 x 2.5 mm; and Group 4: 3.3 x 3.5 mm. An oblique compressive loading test was performed on each sample located in a platform at 30° using a universal testing machine with a load cell of 1,000 kgf and 0.5 mm/min speed until achieving the deformation of abutment's neck. The compressive resistance and its mechanical behavior were recorded for each group and the data were analyzed using ANOVA, the Shapiro-Wilk and Scheffé tests. In addition, the detailed damage of all samples was recorded with a conventional camera linked to the endoscopic equipment. Significant differences were observed among the groups, except between Groups 2 and 3 (p>0.005). All the abutments showed permanent deformations in the upper region and at the transmucosal portion, but the threads of the screws were intact. Fractures were only identified in Groups 3 and 4. Stronger mechanical behavior and compressive resistance was observed in the abutments with 4.5 mm diameter and 2.5 mm transmucosal height.

scholarly journals Revisiting Amalgam: A Comparative Study between Bonded Amalgam Restoration and Amalgam Retained with Undercuts

2011 ◽  
Vol 12 (3) ◽  
pp. 164-170 ◽  
Author(s):  
Indra Gupta ◽  
Satyendra Gupta ◽  
Anjali Kothari
Keyword(s):  
Comparative Study ◽  
Testing Machine ◽  
In Vitro Study ◽  
Tooth Structure ◽  
Group 4 ◽  
Amalgam Restoration ◽  
Group 2 ◽  
Amalgam Restorations ◽  
Group 1

ABSTRACT Aim To compare the retention of amalgam restorations in bonded amalgam restoration and restorations with undercuts. Background With improvement in adhesive technology problem associated with conventional preparation for amalgam restorations mainly compromised resistance form of tooth structure have been largely overcome. Materials and methods Forty caries free extracted molars were used. A basic box preparation was done proximally with buccoproximal and linguoproximal walls diverging at 45° angle and the axial wall is 1.3 mm in dentin. Group 1 – Teeth with basic box preparation. Group 2 – Teeth with box preparation for bonded amalgam. Group 3 – Teeth with box preparation and proximal retention grooves. Group 4 – Teeth with box preparation and occlusal dovetail. Group 1, 3 and 4 were restored with silver amalgam and group 2 restored with resin-bonded amalgam. All samples were subjected to simulated occlusal load against marginal ridge using a blunt stainless steel point in an Instron testing machine. The force in kilogram required to dislodge the restorations as well as the type and location of failure were recorded. Result The main force required to dislodge the restoration was least in group 1 and 3 and maximum in group 2. Conclusion The in vitro study showed that the amalgam bonding technique, using an adhesive resin liner in proximal box form preparation, was more effective than either box form with proximal grooves or dovetails or proximal box only in providing resistance to displacement. Clinical significance Amalgam bonding eliminates the unnecessary removal of sound tooth structure during cavity preparations. How to cite this article Gupta I, Gupta S, Kothari A. Revisiting Amalgam: A Comparative Study between Bonded Amalgam Restoration and Amalgam Retained with Undercuts. J Contemp Dent Pract 2011;12(3):164-170.

scholarly journals Effect of Reinforcement on the Fracture Resistance of Endodontically Treated Molars by Various Bonded Restorations-An In Vitro Study

2015 ◽  
Vol 03 (02) ◽  
pp. 103-111
Author(s):  
Jaidev Dhillon ◽  
Sachin Passi ◽  
Ajay Chhabra ◽  
◽  
Keyword(s):  
Fracture Resistance ◽  
Resin Composite ◽  
Testing Machine ◽  
In Vitro Study ◽  
Group 4 ◽  
Significant Difference ◽  
Group 3 ◽  
Group 2 ◽  
Group 1

Abstract Objective: To compare and evaluate the fracture resistance of endodontically treated molars reinforced with various bonded restorations and to study the type of fractures in various restorations. Methods: Forty extracted mandibular molars were endodontically treated. MOD (Mesio-Occluso-Distal) cavities were prepared and Mesio-Buccal cusp was reduced in all to provide cuspal coverage. All the teeth were then divided into 4 groups. The cavities in group 1(control) were filled with high copper amalgam. Group 2 was restored with direct resin composite. In group 3 after the priming and bonding procedures as in group 2, cavity surfaces were coated with flowable resin composite. Before curing a piece of polyethylene ribbon fiber was cut and coated with adhesive resin and was embedded inside the flowable composite. The resin composite was cured with visible light cure (VLC) gun. For group 4, restorations were done according to the recommendations provided by the manufacturers of SR Adoro (Ivoclar-Vivadent, Schaan, Liechtenstein) composite material. Compressive fracture strength test was performed after at least 24 hours of the fabrication of the specimens, by application of compressive loading in a Universal testing machine, applied on the occlusal aspect of each specimen with a steel bar. The mean loads necessary to fracture were recorded in Newton and the results were statistically analyzed. Results: Group 4 (indirect composite inlay) had the greater fracture resistance and group 1(Amalgam) had the poorest. Difference between group 1 and 3, group 1 and 4, group 2 and 4 were statistically significant. No statistically significant difference was found between group 1 and 2, group 2 and 3, group 3 and 4. Predominant type of fracture in group 1 and 3 was fracture of tooth below cemento enamel junction at tooth restoration interface without mesio buccal cusp involvement. In group 2 and 4, predominant fractures were of tooth below cemento enamel junction through center of restoration without mesio–buccal cusp involvement.

In-vivo evaluation of the effect of cyanoacrylate on prosthetic vascular graft infection – does cyanoacrylate increase the severity of infection?

VASA ◽  
2020 ◽  
Vol 49 (4) ◽  
pp. 281-284
Author(s):  
Atıf Yolgosteren ◽  
Gencehan Kumtepe ◽  
Melda Payaslioglu ◽  
Cuneyt Ozakin
Keyword(s):  
Vascular Graft ◽  
Graft Infection ◽  
Vascular Graft Infection ◽  
Group 4 ◽  
Significant Difference ◽  
Group 3 ◽  
Group 2 ◽  
Prosthetic Vascular Graft Infection ◽  
Group 1

Summary. Background: Prosthetic vascular graft infection (PVGI) is a complication with high mortality. Cyanoacrylate (CA) is an adhesive which has been used in a number of surgical procedures. In this in-vivo study, we aimed to evaluate the relationship between PVGI and CA. Materials and methods: Thirty-two rats were equally divided into four groups. Pouch was formed on back of rats until deep fascia. In group 1, vascular graft with polyethyleneterephthalate (PET) was placed into pouch. In group 2, MRSA strain with a density of 1 ml 0.5 MacFarland was injected into pouch. In group 3, 1 cm 2 vascular graft with PET piece was placed into pouch and MRSA strain with a density of 1 ml 0.5 MacFarland was injected. In group 4, 1 cm 2 vascular graft with PET piece impregnated with N-butyl cyanoacrylate-based adhesive was placed and MRSA strain with a density of 1 ml 0.5 MacFarland was injected. All rats were scarified in 96th hour, culture samples were taken where intervention was performed and were evaluated microbiologically. Bacteria reproducing in each group were numerically evaluated based on colony-forming unit (CFU/ml) and compared by taking their average. Results: MRSA reproduction of 0 CFU/ml in group 1, of 1410 CFU/ml in group 2, of 180 200 CFU/ml in group 3 and of 625 300 CFU/ml in group 4 was present. A statistically significant difference was present between group 1 and group 4 (p < 0.01), between group 2 and group 4 (p < 0.01), between group 3 and group 4 (p < 0.05). In terms of reproduction, no statistically significant difference was found in group 1, group 2, group 3 in themselves. Conclusions: We observed that the rate of infection increased in the cyanoacyrylate group where cyanoacrylate was used. We think that surgeon should be more careful in using CA in vascular surgery.

Does Perioperative Hemoglobin A1c Level Affect the Incidence, Pattern and Mortality of Lower Extremity Amputation?

2019 ◽  
Vol 17 (4) ◽  
pp. 354-364
Author(s):  
Hassan Al-Thani ◽  
Moamena El-Matbouly ◽  
Maryam Al-Sulaiti ◽  
Noora Al-Thani ◽  
Mohammad Asim ◽  
...  
Keyword(s):  
Glycemic Control ◽  
Lower Extremity ◽  
Hazard Ratio ◽  
Lower Extremity Amputation ◽  
Group 4 ◽  
Group 3 ◽  
Group 5 ◽  
Group 2 ◽  
Extremity Amputation ◽  
Group 1

Background: We hypothesized that perioperative HbA1c influenced the pattern and outcomes of Lower Extremity Amputation (LEA). Methods: A retrospective analysis was conducted for all patients who underwent LEA between 2000 and 2013. Patients were categorized into 5 groups according to their perioperative HbA1c values [Group 1 (<6.5%), Group 2 (6.5-7.4%), Group 3 (7.5-8.4%), Group 4 (8.5-9.4%) and Group 5 (≥9.5%)]. We identified 848 patients with LEA; perioperative HbA1c levels were available in 547 cases (Group 1: 18.8%, Group 2: 17.7%, Group 3: 15.0%, Group 4: 13.5% and Group 5: 34.9%). Major amputation was performed in 35%, 32%, 22%, 10.8% and 13.6%, respectively. Results: The overall mortality was 36.5%; of that one quarter occurred during the index hospitalization. Mortality was higher in Group 1 (57.4%) compared with Groups 2-5 (46.9%, 38.3%, 36.1% and 31.2%, respectively, p=0.001). Cox regression analysis showed that poor glycemic control (Group 4 and 5) had lower risk of mortality post-LEA [hazard ratio 0.57 (95% CI 0.35-0.93) and hazard ratio 0.46 (95% CI 0.31-0.69)]; this mortality risk persisted even after adjustment for age and sex but was statistically insignificant. The rate of LEA was greater among poor glycemic control patients; however, the mortality was higher among patients with tight control. Conclusion: The effects of HbA1c on the immediate and long-term LEA outcomes and its therapeutic implications need further investigation.

scholarly journals Fracture Load of Metal, Zirconia and Polyetheretherketone Posterior CAD-CAM Milled Fixed Partial Denture Frameworks

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 959
Author(s):  
Verónica Rodríguez ◽  
Celia Tobar ◽  
Carlos López-Suárez ◽  
Jesús Peláez ◽  
María J. Suárez
Keyword(s):  
Computer Aided Design ◽  
Testing Machine ◽  
Fracture Load ◽  
Fracture Pattern ◽  
Bending Test ◽  
Weibull Statistics ◽  
Promising Alternative ◽  
Computer Aided ◽  
Cad Cam ◽  
Group 2

The aim of this study was to investigate the load to fracture and fracture pattern of prosthetic frameworks for tooth-supported fixed partial dentures (FPDs) fabricated with different subtractive computer-aided design and computer-aided manufacturing (CAD-CAM) materials. Materials and Methods: Thirty standardized specimens with two abutments were fabricated to receive three-unit posterior FDP frameworks with an intermediate pontic. Specimens were randomly divided into three groups (n = 10 each) according to the material: group 1 (MM)—milled metal; group 2 (L)—zirconia; and group 3 (P)—Polyetheretherketone (PEEK). The specimens were thermo-cycled and subjected to a three-point bending test until fracture using a universal testing machine (cross-head speed: 1 mm/min). Axial compressive loads were applied at the central fossa of the pontics. Data analysis was made using one-way analysis of variance, Tamhane post hoc test, and Weibull statistics (α = 0.05). Results: Significant differences were observed among the groups for the fracture load (p < 0.0001). MM frameworks showed the highest fracture load values. The PEEK group registered higher fracture load values than zirconia samples. The Weibull statistics corroborated these results. The fracture pattern was different among the groups. Conclusions: Milled metal provided the highest fracture load values, followed by PEEK, and zirconia. However, all tested groups demonstrated clinically acceptable fracture load values higher than 1000 N. PEEK might be considered a promising alternative for posterior FPDs.

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