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Biomedical subjects

L C Breeding

Publications and source records attributed to L C Breeding.

At least 19 recordsLinked to original sources
PubMed1997

Shear bond strengths of a two-paste system resin luting agent used to bond alloys to enamel.

STATEMENT OF PROBLEM: Adhesive resin luting agents are used to successfully bond the metal surfaces of fixed prostheses to teeth. Panavia 21 luting agent is a new addition to the series of Panavia adhesive resin luting agents. PURPOSE: This investigation measured the shear bond strengths of two types of alloy specimens (Olympia and Rexillium III) bonded to prepared human enamel (etched and unetched) with Panavia 21. MATERIAL AND METHODS: After a simulated porcelain firing sequence, the alloy specimens were bonded to the teeth and subjected to shear testing after water storage for 2 weeks, thermocycling for 500 cycles, and water storage for an additional 2 weeks. Data were analyzed with a two-way analysis of variance (alpha = 0.05). RESULTS: The shear bond strengths of Rexillium III and tinplated Olympia specimens bonded to prepared and unetched enamel were significantly lower than for specimens bonded to prepared and etched enamel with Panavia 21 luting agent.

Acid Etching, Dental↗
PubMed1996

Surgical guide fabrication for an angled implant.

This article describes the steps necessary for determining ideal implant abutment position and, subsequently, the optimum implant location that would make this abutment position possible. Procedures necessary for fabricating a surgical guide are explained for placing an ITI angled implant.

Dental Implantation, Endosseous↗
PubMed1996

The effect of simulated function on the retention of bar-clip retained removable prostheses.

Patients wearing bar-clip retained removable prostheses may have loss of retention because of changes within the bar-clip assembly. This in vitro study recorded and compared the retention of one- and two-clip retained simulated mandibular complete denture prostheses before and after simulated function. Cast metal Hader bars and clip holders were used to make 10 one-clip and 10 two-clip specimen pairs. Tensile removal values before and after simulated function were recorded and compared by repeated-measures analysis of variance and Student tau tests (significance level 0.05). The results revealed that the use of two clips instead of one significantly increased retention of the simulated prosthesis. It was also found that there was a significant loss of retention after the specimens were placed on the bars and then removed once for both the one- and two-clip groups. Simulated function did not cause a significant change in retention for either group.

Analysis of Variance↗
PubMed1996

Transfer of gingival contours to a master cast.

This procedure provides a means for transferring intraorally formed gingival sulcular contours surrounding a single-tooth implant-supported provisional restoration to a master cast. When this procedure is used, the final fixed prosthesis may be made in the laboratory with gingival contours identical to those developed on the provisional restoration.

Dental Prosthesis Design↗
PubMed1996

The effect of metal surface treatment on the shear bond strengths of base and noble metals bonded to enamel.

Adhesive resin luting agents provide a way for bonding metal surfaces to teeth through a combination of micromechanical retention to the rough metal surface and chemical adherence to metal oxides. The purpose of this study was to measure the effect of metal alloy surface treatments that would produce different textures and oxide layers on the shear bond strength of three alloys luted to etched enamel with one adhesive resin luting agent (Panavia). After a simulated porcelain firing sequence, high noble (Olympia), noble (Jelstar), and base metal (Rexillium III) alloy specimens were subjected to one of the following treatments: (1) sandblasting and simulated glazing, (2) simulated glazing only, (3) simulated glazing and sandblasting, or (4) simulated glazing, sandblasting, and tin plating. The specimens were bonded to extracted teeth and subjected to shear testing after water storage for 2 weeks, thermocycling for 500 cycles, and water storage for an additional 2 weeks. Data were analyzed with a two-way analysis of variance (alpha = 0.05). The base metal specimens and the tin-plated high noble and noble metal specimen groups exhibited similar mean shear bond strengths that were greater than the other groups. Those high noble and noble metal alloys sandblasted after simulated porcelain firing cycles and before the simulated glaze cycle exhibited nonsignificant increases in shear bond strengths compared with the groups that were either sandblasted after the simulated glaze cycle or not sandblasted at all.

Analysis of Variance↗
PubMed1995

Comparison of screw loosening, rotation, and deflection among three implant designs.

A common problem associated with single tooth implant restorations is abutment screw loosening. Manufacturers of implants have attempted to overcome this problem by incorporating antirotational design characteristics into their systems. Micromovement and torque levels required to loosen abutment screws for straight and angled antirotational screw-retained abutment/implant combinations from three different manufacturers were examined in this in vitro investigation. A custom-built machine was used and each sample was subjected to compressive horizontal reciprocal movements over a 25-degree incline for a simulated 1-month period. Data were generated that showed movements of the crown/abutment complex during force application. The amount of torque necessary to loosen the abutment screws before and after testing was also recorded and compared for each system. The results indicated no significant differences (p < 0.05) among all the straight and angled abutments for the variables studied.

Analysis of Variance↗
PubMed1995

A bonded provisional fixed prosthesis to be worn after implant surgery.

The procedure described provides an esthetic means for inserting a provisional fixed restoration immediately after implant placement surgery. When this procedure is used, it is not necessary to prepare the abutment teeth adjacent to the surgical site for subsequent fixed restorations. This provisional restorative procedure may also be used immediately after extraction of teeth, when abutment tooth preparation is not desired or possible, or after stage II implant surgery when healing caps are inserted.

Acrylic Resins↗
PubMed1995

Mechanical considerations for the implant tooth-supported fixed partial denture.

The implant tooth-supported fixed partial denture presents a biomechanical design problem, because the implant is rigidly fixed within the alveolus, and the tooth is surrounded by a periodontal ligament that allows movement. Nonrigid fixed partial denture designs are advocated by some dentists as a method of compensating for this differential movement. Rigid fixed partial denture designs, however, are advocated by many clinicians. Studies have failed to show the advantage of one design over the other. This study developed an in vitro method for testing such prosthesis designs and measured movement of a natural tooth abutment during simulated function. The movement of the natural tooth abutment was not found to change substantially with the fixed partial denture designs tested.

Alveolar Process↗
PubMed1994

Comparison of shear bond strengths of two resin luting systems for a base and a high noble metal alloy bonded to enamel.

Researchers are investigating the use of noble metals for the fabrication of resin-bonded prostheses because of concerns about health hazards of nickel and beryllium in base metal alloys. Tin-plating has been advocated to improve the bond of resin luting agents to noble metal alloys. Some manufacturers have suggested that tin-plating is unnecessary to bond noble metal alloys to etched enamel with their products. In this study, Rexillium base metal and Olympia noble metal alloy specimens were bonded to extracted human teeth with the use of two resin luting agents (F21 and Panavia OP). One third of the noble metal specimens were tin-plated, one third were oxidized, and one third were oxidized and sandblasted. Each of the bonded specimens were thermocycled and subjected to a shear force until bond failure. The base metal specimens bonded with Panavia OP luting agent exhibited the greatest mean shear bond strengths. The tin-plating surface treatment significantly increased the mean shear bond strengths of Olympia noble metal specimens.

Adhesives↗
PubMed1994

Custom impression trays. Part III: A stress distribution model.

All resins used to make custom impression trays exhibit plastic deformation at some force value; therefore it is important to compare the physical property values of such materials with the stresses to which impression trays are subjected during dental procedures. A simple mathematical model of a custom tray was developed to predict stress distributions in this final part of a three-part investigation. Experimental stress analysis of such a tray confirmed the accuracy of the model, which was then used to predict the maximum stress experienced by the tray during removal of a completed impression from the oral cavity. The results of this analysis indicated that these stresses would be significantly lower than the yield stress for a commonly used polymethyl methacrylate resin or a light-polymerized resin. The stresses were also sufficiently low for us to conclude that thermoplastic resins would not permanently deform; however, the stresses encountered in the experimental confirmation procedure were close to the yield stress values for these materials.

Dental Impression Materials↗
PubMed1994

Custom impression trays: Part I--Mechanical properties.

Dimensional stability of custom impression trays is an important factor in determining the degree of accuracy achieved in forming a master cast. Such trays must remain stable over time and must not exhibit permanent deformation when a completed impression is removed from the oral cavity. Measurement of the mechanical properties allows comparison between various tray materials and is useful in interpreting data on stresses incurred during removal of the completed impression. In Part I of this three-part series, the various mechanical properties of five tray resins: one autopolymerizing polymethyl methacrylate, one light-polymerizing, and three brands of thermoplastic resins were recorded and compared. The thermoplastic resins studied in this investigation exhibited lower measured values for the strength and elastic modulus properties than the light-polymerizing resin and the autopolymerizing polymethyl methacrylate resin studied.

Dental Impression Technique↗
PubMed1994

Use of light-polymerizing restorative materials in diagnostic cast modification procedures.

During the treatment-planning phase and before provisional restorations are made for the partially edentulous patient, it is often necessary to complete diagnostic cast modification procedures. Traditionally wax has been used for this purpose; therefore, it is necessary to duplicate the modified cast before fabrication of a vacuum-formed matrix. The cast duplication procedure can be eliminated by the use of light-polymerizing provisional restorative materials for cast modification instead of wax. Diagnostic casts for two patients are presented in this article, where techniques for using such a light-polymerizing material are described.

Acrylic Resins↗
PubMed1994

Accuracy of three interocclusal recording materials used to mount a working cast.

When remaining occlusal contacts of a dental posterior quadrant have been prepared to receive complete or partial coverage restorations, it is necessary to use an interocclusal recording material to approximate the casts for laboratory mounting procedures. Inaccuracy in working cast approximation leads to occlusal discrepancies in the fabricated restorations that require correction by the dentist at the time of insertion. Traditionally waxes, impression compounds, plasters, and zinc oxide-eugenol pastes have been used intraorally to record maxillomandibular relationships. Elastomeric materials have also been advocated. Manufacturers of thermoplastic resins have recently suggested that these materials may be used with ease and accuracy for interocclusal records. This investigation measured and compared the accuracies of a thermoplastic resin, an acrylic resin, and a vinyl polysiloxane interocclusal recording material. A measuring method was developed in which a computerized axiograph was used to record positional errors in three planes, next to the posterior teeth, with the interocclusal recording materials listed.

Acrylic Resins↗
PubMed1994

Custom impression trays. Part II: Removal forces.

When choosing a material for making custom impression trays, it is important to understand the forces to which the tray will be subjected during removal of the completed impression from the oral cavity. Such forces have not been recorded in the dental literature. The purpose of Part II of this three-part series was to record these forces in vitro, using two different tray-removal methods. A polymethyl methacrylate custom tray was used during this study. Results from this investigation indicated that it is easier to remove a completed impression, made with a custom tray, by a single point of anterior force application (224 N) than by force application evenly around the tray (514 N). The recorded force values from this investigation will be used in Part III of this series.

Acrylic Resins↗
PubMed1993

Removing a cemented fixed prosthesis using a crown remover.

It may be necessary to remove a fixed prosthesis for various reasons. This article describes a simple, quick, and inexpensive solution to a difficult problem. The technique has the advantage of saving the patient both money and time.

Dental Debonding↗
PubMed1993

The effect of fatigue on the shear bond strength of resin bonded to porcelain.

PURPOSE: The objective of this study was to determine whether fatigue cycling affects the shear bond strength of a resin that is initially strongly bonded to porcelain. MATERIALS AND METHODS: Thirty-five disks of a feldspathic/leucite porcelain were fired on a phosphate-bonded investment material. Each disk was etched with hydrofluoric acid and treated with a silane solution and an adhesive. Resin cement composite cylinders were applied to the treated porcelain and light cured. All specimens were stored for 1 week in distilled water at 37 degrees C and then thermocycled for 1000 cycles in water between 2 degrees C and 50 degrees C. Fifteen of the specimens were randomly selected as control specimens. The remaining were subjected to fatigue cycling. A shear load was applied parallel to the bonded surface and cycled in a square wave between 0 and 26 N at 2 Hz for 27,500 cycles. All specimens were fractured in shear at 1.27 mm/min, and the shear bond strength was determined. RESULTS: Fifteen percent of fatigued specimens and 6.7% of the control specimens showed at least partial adhesive failure. All other specimens in both groups failed cohesively in the porcelain. There was no significant difference in the mean bond strengths of the fatigued and control groups (analysis of covariance, P > .05). CONCLUSIONS: For the conditions investigated, cyclic fatigue did not reduce the bond strength of this resin/porcelain system.

Analysis of Variance↗