The role of welding techniques in the biomechanical behavior of implant-supported prostheses.

This in vitro study investigated the role of welding techniques of implant-supported prostheses in the 2D and 3D marginal misfits of prosthetic frameworks, strain induced on the mini abutment, and detorque of prosthetic screws. The correlations between the analyzed variables were also investigated. Frameworks were cast in commercially pure titanium (cp-Ti).

Maxillary "All-On-Four" treatment using zygomatic implants. A mechanical analysis.

Objective: Zygomatic implants may be used for dental rehabilitation in atrophic maxillae. The aim of this study was to establish experimentally the areas of stress distribution using 2 kinds of "All-On-Four" maxillary procedures.

Study Design: The best position to insert the implants was selected using polyurethane craniomaxillary models and surgical guides were made.

Stress on external hexagon and Morse taper implants submitted to immediate loading.

Background/aims: This study aimed to evaluate the stress distribution around external hexagon (EH) and Morse taper (MT) implants with different prosthetic systems of immediate loading (distal bar (DB), casting technique (CT), and laser welding (LW)) by using photoelastic method.

Methods: Three infrastructures were manufactured on a model simulating an edentulous lower jaw. All models were composed by five implants (4.

Photoelastic analysis of stresses transmitted by complete dentures lined with hard or soft liners.

Stresses transmitted on the alveolar bone ridge by lined conventional complete mandibular dentures can decrease the bone absorption level. The aim of this in vitro study was to evaluate the stresses induced on the alveolar bone ridge of lined conventional complete mandibular dentures by using photoelastic analysis. One maxillary and three mandibular conventional dentures were developed for the following treatments: 1 - Unlined denture (control), 2 - Denture lined with resin-based material, and 3 - Denture lined with silicone-based material.

Laser and plasma dental soldering techniques applied to Ti-6Al-4V alloy: ultimate tensile strength and finite element analysis.

Statement Of Problem: The literature provides limited information regarding the performance of Ti-6Al-4V laser and plasma joints welded in prefabricated bars in dental applications.

Purpose: The purpose of this study was to evaluate the mechanical strength of different diameters of Ti-6Al-4V alloy welded with laser and plasma techniques.

Material And Methods: Forty-five dumbbell-shaped rods were created from Ti-6Al-4V and divided into 9 groups (n=5): a control group with 3-mm and intact bars; groups PL2.

Strain gauges's analysis on implant-retained prosthesis' cast accuracy.

Introduction: A proper cast is essential for a successful rehabilitation with implant prostheses, in order to produce better structures and induce less strain on the implants.

Aims: The aim of this study was to evaluate the precision of four different mold filling techniques and verify an accurate methodology to evaluate these techniques.

Materials And Methods: A total of 40 casts were obtained from a metallic matrix simulating three unit implant-retained prostheses.

Photoelastic analysis of fixed partial prosthesis crown height and implant length on distribution of stress in two dental implant systems.

The aim of this study was to evaluate by photoelastic analysis stress distribution on short and long implants of two dental implant systems with 2-unit implant-supported fixed partial prostheses of 8 mm and 13 mm heights. Sixteen photoelastic models were divided into 4 groups: I: long implant (5 × 11 mm) (Neodent), II: long implant (5 × 11 mm) (Bicon), III: short implant (5 × 6 mm) (Neodent), and IV: short implants (5 × 6 mm) (Bicon). The models were positioned in a circular polariscope associated with a cell load and static axial (0.

Photoelastic analysis of all-on-four concept using different implants angulations for maxilla.

Conventional tilted implants are used in oral rehabilitation for heavily absorbed maxilla to avoid bone grafts; however, few research studies evaluate the biomechanical behavior when different angulations of the implants are used. The aim of this study was evaluate, trough photoelastic method, two different angulations and length of the cantilever in fixed implant-supported maxillary complete dentures. Two groups were evaluated: G15 (distal tilted implants 15°) and G35 (distal tilted implants 35°) n = 6.

Prosthetic improvement of pronounced buccally positioned zygomatic implants: a clinical report.

This report presents a prosthetic technique for the improvement of surgically positioned, buccally placed zygomatic implants with the use of custom abutments for improved retention screw position and an esthetic implant reconstruction. The patient presented four zygomatic implants with pronounced buccal inclination. The anterior implants were inclined toward the location where the anterior artificial teeth should be placed during rehabilitation.

Tensile and flexural strength of commercially pure titanium submitted to laser and tungsten inert gas welds.

This study evaluated the tensile and flexural strength of tungsten inert gas (TIG) welds in specimens made of commercially pure titanium (CP Ti) compared with laser welds. Sixty cylindrical specimens (2 mm diameter x 55 mm thick) were randomly assigned to 3 groups for each test (n=10): no welding (control), TIG welding (10 V, 36 A, 8 s) and Nd:YAG laser welding (380 V, 8 ms). The specimens were radiographed and subjected to tensile and flexural strength tests at a crosshead speed of 1.

Stress distribution in Co-Cr implant frameworks after laser or TIG welding.

Lack of passivity has been associated with biomechanical problems in implant-supported prosthesis. The aim of this study was to evaluate the passivity of three techniques to fabricate an implant framework from a Co-Cr alloy by photoelasticity. The model was obtained from a steel die simulating an edentulous mandible with 4 external hexagon analog implants with a standard platform.

Micro-leakage at the implant-abutment interface with different tightening torques in vitro.

Objectives: This study evaluated the microleakage at the implant/abutment interface of external hexagon (eH) implants and abutments with different amounts of bacteria and tightening torques.

Material And Methods: A bacterial suspension was prepared to inoculate the implants. The first phase of this study used nine EH implants and abutments that were divided into three groups with different amounts of bacterial suspension (n=3): V0.

Influence of methodologic aspects on the results of implant-abutment interface microleakage tests: a critical review of in vitro studies.

Purpose: This study sought to evaluate the influence of methodologic aspects on variations in the findings of in vitro microleakage studies of the implant-abutment interface.

Materials And Methods: The MEDLINE, EMBASE, and Cochrane Library databases were consulted for in vitro studies published between 1990 and August 2011. Date from the studies that met the inclusion and exclusion criteria were arranged in tables and subjected to descriptive analysis.

Fatigue performance of joints executed in pure titanium structures with several diameters.

This study evaluated fatigue strength of CP-Ti laser-welded joints. Sixty (20/diameter) CP-Ti casted dumbbell rods with diameters of 1.5, 2.

Fatigue strength: effect of welding type and joint design executed in Ti-6Al-4V structures.

Background: This study evaluated the fatigue strength of Ti-6Al-4V-machined structures submitted to laser (L)-welding and TIG (TIG)-welding procedures, varying the joint designs.

Materials And Methods: Seventy dumbbell rods were machined in Ti-6Al-4V alloy with central diameters of 3.5 mm.

Effect of toothbrushing, chemical disinfection and thermocycling procedures on the surface microroughness of denture base acrylic resins.

Objective: This study verified the surface microroughness of denture acrylic resins submitted to toothbrushing, chemical disinfection and thermocycling procedures.

Material And Methods: Samples were prepared according to conventional, microwaved and boiled resins and submitted to microroughness measurements before and after procedures using a profilometer (Ra). Data were subjected to anova and Tukey's test (5%).

Evaluation of anodic behavior of commercially pure titanium in tungsten inert gas and laser welds.

Purpose: This study evaluated the resistance to corrosion in welds made with Tungsten Inert Gas (TIG) in specimens made of commercially pure titanium (cp Ti) in comparison with laser welds.

Materials And Methods: A total of 15 circular specimens (10-mm diameter, 2-mm thick) were fabricated and divided into two groups: control group-cp Ti specimens (n = 5); experimental group-cp Ti specimens welded with TIG (n = 5) and with laser (n = 5). They were polished mechanically, washed with isopropyl alcohol, and dried with a drier.

Radiographic inspection of porosity in Ti-6Al-4V laser-welded joints.

Widely used in dentistry, Ti-6Al-4V alloy is difficult to cast and solder, as it frequently exhibits pores inside the structure. This study was conducted to evaluate the effect of joint openings and diameters of laser-welded joints executed in Ti-6Al-4V structures on the presence of pores as checked by radiographic procedures. Sixty dumbbell rods with central diameters of 1.

Effect of accelerated aging on permanent deformation and tensile bond strength of autopolymerizing soft denture liners.

Purpose: The aim of this study was to evaluate the effect of different accelerated aging times on permanent deformation and tensile bond strength of two soft chairside liners, acrylic resin (T) and silicone (MS) based.

Materials And Methods: Different specimens were made for each test of each reliner. The specimens (n = 10) were submitted to accelerated aging for 2, 4, 8, 16, 32, and 64 cycles.

Effects of laser-weld joint opening size on fatigue strength of Ti-6Al-4V structures with several diameters.

This study was conducted to evaluate the fatigue strength of Ti-6Al-4V laser-welded joints with several diameters and joint openings. Sixty dumbbell rods were machined in Ti-6Al-4V alloy with central diameters of 1·5, 2·0 and 3·5 mm. The specimens were sectioned and then welded using two joint openings (0·0 and 0·6 mm).

Radiographic inspection of porosity in pure titanium dumbbell castings.

Background:   Titanium frameworks are frequently indicated for implant supported prostheses; however, voids are usually encountered inside cast titanium.

Objective:   This study aimed to confirm the efficacy of a radiographic technique for inspection of porosity in commercially pure titanium castings with different diameter.

Materials And Methods:   Sixty dumbbell rods (n=20) with a central 1.

Effect of retorque on loosening torque of prosthetic screws under two levels of fit of implant-supported dentures.

This study evaluated the influence of retorque on loosening torque (Lt) of prosthetic screws in implant-supported dentures with different fit levels. Ten mandibular implant-supported dentures were fabricated and then 20 cast models were then prepared using prosthetic structures to create 2 fit levels: passive fit (Pf) and misfit (Mf). Two tightening techniques were also evaluated: initial torque only (T1); and initial torque and retorque after 10 min (T2).

Vickers hardness of cast commercially pure titanium and Ti-6Al-4V alloy submitted to heat treatments.

The purpose of this study was to evaluate the effect of heat treatments on the Vickers hardness of commercially pure titanium and Ti-6Al-4V cast alloys. Six-millimeter-diameter cylindrical specimens were cast in a Rematitan System. Commercially pure titanium and Ti-6Al-4V alloy specimens were randomly assigned to 3 groups (n=10) that received the following heat treatments: control (no heat treatment); treatment 1 (T1): heating at 750 degrees C for 2 h; and treatment 2 (T2): annealing at 955 degrees C for 1 h and aging at 620 degrees C for 2 h.

Influence of chemical and mechanical polishing on water sorption and solubility of denture base acrylic resins.

Influence of polishing methods on water sorption and solubility of denture base acrylic resins was studied. Eighty samples were divided into groups: Classico (CL), and QC 20 (QC) - hot water bath cured; Acron MC (AC), and Onda Cryl (ON) - microwave cured; and submitted to mechanical polishing (MP) - pumice slurry, chalk powder, soft brush and felt cone in a bench vise; or chemical polishing (CP) - heated monomer fluid in a chemical polisher. The first desiccation process was followed by storage in distilled water at 37 +/- 1 degrees C for 1 h, 1 day, 1, 2, 3 and 4 weeks.

Surface roughness of acrylic resins submitted to mechanical and chemical polishing.

Surface roughness is extremely important as it influences micro-organism accumulation and consequently oral health. The aim of the present study was to evaluate the influence of mechanical polishing (MP) and chemical polishing (CP) on surface roughness of four heat-cured denture base acrylic resins. Twenty sample discs were prepared for each of the following acrylic resins: Classico (CL), QC 20 (QC), Acron MC (AC) and Onda Cryl (ON).