PubMed Health⌕ Search

Biomedical subjects

H D Stipho

Publications and source records attributed to H D Stipho.

8 recordsLinked to original sources
PubMed2001

Repair of denture base resins with visible light-polymerized reline material: effect on tensile and shear bond strengths.

STATEMENT OF PROBLEM: Triad visible light-polymerized (VLP) reline resin has the potential to repair denture bases from other resin systems with the elimination of flasking/deflasking procedures. PURPOSE: This study measured the tensile and shear bond strengths of Triad VLP, PMMA, and glass-fiber-reinforced PMMA (GF-PMMA) acrylic resins before and after repair with Triad VLP reline material. MATERIAL AND METHODS: Fifty-six specimens were fabricated from Triad VLP, PMMA, and GF-PMMA denture base resins. Both Triad VLP reline material and autopolymerizing acrylic resins were used to repair identical laboratory fabricated resin joints. Twenty-eight rectangular specimens (in 4 different groups of 7 each) were prepared to study the shear bond strength of Triad reline material used to repair different denture base resin joints. RESULTS: Statistically significant differences (P< .0001) were found between the tensile strengths of specimens repaired with the Triad VLP reline resin used as a repair agent and those repaired with the autopolymerizing resin. The tensile strength of the Triad VLP denture base resin was found to be higher than that of both the PMMA and GF-PMMA acrylic resins. CONCLUSION: The low tensile and shear bond strengths found after the repair of PMMA and GF-PMMA acrylic resins with Triad VLP reline material were attributed to a lack of cohesion/adhesion between the Triad VLP reline material and the interfaces of the treated sites. The use of Triad VLP reline material to repair Triad VLP denture base resin produced the highest strengths.

Acrylic Resins↗
PubMed1998

Repair of acrylic resin denture base reinforced with glass fiber.

STATEMENT OF PROBLEM: The ultimate goal of any denture repair is to restore the original strength of the denture and to avoid further fracture. PURPOSE: This study investigated the strength and deflection of repaired acrylic resin joints reinforced with various glass fiber concentrations. MATERIAL AND METHODS: Transverse strength, maximum deflection, and modulus of elasticity of glass fiber-reinforced polymethyl methacrylate acrylic resin were studied with a 3-point load test on 54 intact specimens. Six concentrations of type B glass fiber specimens were prepared (n = 9 per each fiber group). Fractured joint margins were rounded, a 2-mm gap was placed between them, and then they were repaired with autopolymerizing acrylic resin and retested. RESULTS: Transverse strength, maximum deflection, and the stiffness of all joints were significantly lower after the repair. Among the groups tested, the units treated with 1% glass fiber displayed the highest transverse strength before and after repair. Modulus of elasticity of the repaired 1% fiber concentration units was enhanced by approximately 25% over those repaired but untreated with glass fiber (0% fiber).

Analysis of Variance↗
PubMed1998

Effect of glass fiber reinforcement on some mechanical properties of autopolymerizing polymethyl methacrylate.

PURPOSE: This study investigated the different effects of quantitative percentages of glass fiber intensity on the transverse strength, maximum deformation, and the modulus of elasticity of acrylic resin. MATERIALS AND METHODS: Fifty-four specimens were formed in a specially designed mold to produce identical specimens in accordance with the manufacturer's recommendations. Six percentages of glass fiber reinforcement in loose random form were studied. Each glass fiber treatment percentage (0%, 1%, 2%, 5%, 10%, 15%) was related to the total powder/liquid mass. RESULTS: The results indicated that 1% glass fiber treatment enhanced the transverse strength of the tested specimen. Maximum deformation at failure in the tested treatment groups was found to be different. The interaction of glass fiber concentration on fracture strength and deformation was significant (p < 0.0001). CONCLUSION: The 1% glass fiber concentration was found to give the best fracture strength and deformation results. Significantly higher glass fiber percentages was found to weaken the resin.

Analysis of Variance↗
PubMed1994

Stabilized record baseplate with cold curing acrylic resin.

A well adapted and structurally stable baseplate is very important to verify the accuracy of previous records in denture construction. Shellac baseplate is widely recognized for records base, it is inexpensive and readily available in uniform shapes, but it lacks adequate strength and dimensional stability. Reheating makes it brittle, thus limit its use. This paper discusses a technique used to stabilize and improve the strength of shellac baseplates. The technique was found simple, easy to adapt, produce and transfer accurate maximandibular jaw relations record during denture construction.

Acrylic Resins↗
PubMed1985

Boxing impressions with irreversible hydrocolloid.

A boxing method that uses irreversible hydrocolloid for boxing final impressions made with four different final impression materials was described. The boxing material separated from the impression in one piece with all impression materials. No separation media was required. In addition, the accuracy of the borders of all impression materials was equally well preserved.

Colloids↗