Make luster tabs for use in matching texture of porcelain surfaces.
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Biomedical subjects
Publications and source records attributed to L C Breeding.
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A soft tissue cast permits the technician to make fixed prostheses with optimal contours. This article describes a quick and easy procedure for making a vinylsiloxane soft tissue cast directly in the impression.
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.
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.
This study compared the linear dimensional change and tensile strengths of three indexing materials used for aligning joints to be soldered. Sixty rods 6 mm in diameter and 18 mm in length were made from base metal. The rods were divided into three groups of 10 pairs each, and a simulated solder gap was created between the rods in each pair. Ten simulated gaps were indexed with Duralay resin, 10 were indexed with Relate resin, and 10 were indexed with ZAPIT cyanoacrylate material. Measurements were made of each pair, before and after indexing, and the tensile strength of each indexed pair was measured and recorded. Linear measurements showed no significant difference between any of the groups. However, significant differences in tensile strength were found among all the materials tested.
When removal of the provisionally cemented superstructure from a cemented abutment becomes necessary, the retentive strengths of the abutment/fixture and superstructure/abutment luting agents become important considerations. This study compared the retentive strengths of castings cemented to machined titanium implant abutments and to a human premolar with three provisional luting agents. Also tested were the retentive strengths of cast noble metal implant abutments cemented into titanium fixtures with three permanent luting agents both dry and after storage in 0.9% physiologic saline for 30 days at 37 degrees C. No significant differences (alpha < 0.05) were noted in retentive values between the cemented castings on the titanium abutments and the natural tooth. The Temp Bond zinc oxide-eugenol luting agent exhibited a lower mean retentive strength than the IRM reinforced zinc oxide-eugenol and Life calcium hydroxide luting agents. Ketac Cem glass-ionomer cemented abutments that were stored in saline exhibited a significantly higher mean retentive strength than abutments cemented with either Core Paste or Resiment resin luting agents. On the basis of results from this study, it may be concluded that superstructures provisionally cemented with Temp Bond, IRM, or Life luting agents may be removed from implant abutments without disturbing the abutment/fixture or implant bond.
This investigation compared the transverse strengths of three denture base resins with and without polyethylene reinforcement fibers. These fibers were incorporated in 10 specimens each of a high-impact strength resin, a rapid heat-polymerized resin, and a light-activated resin. Each specimen was broken on an Instron universal testing machine using a three-point load after processing and air drying. The values obtained were then compared with values previously recorded for the same type of specimens without incorporated fibers. Only the light-activated denture base resin specimens exhibited a significantly higher mean transverse strength after polyethylene fiber reinforcement.
It has been shown that denture base resins shrink during curing and expand during storage in water. This investigation measured and compared linear dimensional changes of three denture base resins that occurred during processing and after storage in water for 30, 60, and 90 days. Triad, Accelar 20, and Lucitone 199 long- and short-cured resins were studied, and it was found that Accelar 20 resin exhibited the least curing shrinkage and Lucitone 199 resin short-cured exhibited the most. However, no significant differences occurred between the groups. After 90 days of water storage, the only resin that exhibited a shrinkage from the processed state was Accelar 20. All of the expansion or shrinkage changes were so small that they were not statistically significant and should not be clinically detectable.
There has been an increase in the use of prefabricated post systems to restore endodontically treated teeth. Various restorative materials are being used as core buildups on these posts. The purpose of this study was to compare three core materials that are used with prefabricated stainless steel posts. Two types of prefabricated posts were placed in extracted teeth, followed by core buildups in amalgam, composite resin, or glass ionomer. The teeth were prepared for full cast crowns with the margins of the crown preparation extending 0.5 to 1.0 mm below the margins of the core buildup. Crowns were fabricated and cemented with zinc phosphate cement. A custom-designed chewing machine was used to cyclically load the teeth with vertical and horizontal forces for one million cycles or until failure occurred. Results indicated highly significant differences in the survival of the post-core-crown restorations depending on which core buildup material was used. Amalgam cores had the lowest failure rate, followed by composite resin cores. All teeth restored with crowns over glass-ionomer core buildup failed. The type of prefabricated post used had no effect on the survival of the post-core-crown restorations regardless of the core buildup used.
The dentition of partially edentulous patients with an anterior modification space may be restored in several ways. If a removable partial denture is selected as the treatment of choice, denture tooth selection, direct retainer display, and anterior-posterior rotation may be sources of concern for the patient and dentist. A way to overcome the treatment problems associated with these partially edentulous patients is use of a Hader bar and clip-retained removable partial denture with the attachment of an anterior porcelain-fused-to-metal facade. This article describes this treatment option and the technique for fabrication.
Elastomeric impression materials are popular for making interocclusal records to mount casts on dental articulators. The resistance of these materials to compressive forces is critical, because any deformation during the recording or mounting process could result in inaccurate articulation of casts and faulty fabrication of restorations. This investigation compared the deformation of designated thicknesses (2 mm, 5 mm, 10 mm, and 20 mm) for four elastomeric interocclusal recording materials (Blu-Mousse, Stat BR, Ramitec, and Regisil) when subjected to a 25 N compressive load. Compressive distortions of clinical significance were recorded for all of the materials with various thicknesses. The Blu-Mousse vinyl polysiloxane registration material exhibited the greatest resistance to compression for the designated thicknesses, and these resistance values were significantly lower than those of the other recording materials with thicknesses of 5, 10, and 20 mm (alpha < 0.05).
The purposes of this study were to determine the amount of die space necessary to reduce seating discrepancies of castings cemented onto implant abutments and to determine the effect that this space created for the luting-agent has on crown retention. Noble metal castings were made with 0.000 inch, 0.001 inch, 0.002 inch, and 0.003 inch spacing for premanufactured titanium implant abutments. The castings were cemented onto the abutments with three permanent luting agents. Seating discrepancies of each casting/abutment combination were measured, and the castings were pulled from the abutments by use of tensile force. The results of this study indicate that the use of die spacing decreased seating discrepancies and increased retentive values under the test conditions.
This investigation evaluated the operating characteristics of a recently introduced tooth dryer and its effect on the bond strength of three composite resins to etched enamel. The effect of varying air pressure, distance from the tip of the tooth dryer, and distance laterally from mid-air stream on temperature were measured using a rapid-response thermocouple. Specimens were subjected to shear forces either immediately after bonding or after 5 days of water storage. The air stream required from 32 to 41 seconds to reach maximal temperature; however, more than 90% of the maximal temperature was obtained in 20 seconds. There was an increase in temperature with increased air pressure and a decrease in temperature with increasing distance from the tip. The temperature dropped rapidly laterally from the center of the air stream. The shear bond strength measurements were significantly higher for the specimens prepared using the tooth dryer for one composite resin tested immediately after bonding; there was no statistically significant difference for the other resins. The effect of warm air on the shear bond strength of composite resins to etched enamel may be dependent on the resin used and the time between bonding and testing.
This study tested the effect of fixed partial dentures on hypermobile abutment teeth with substantially reduced levels of periodontal attachment. One abutment tooth and one control (nonabutment) tooth of the same type and periodontal condition were selected for study in adults. Treatment consisted of periodontal therapy and a 3- or 4-unit fixed partial denture, after which all subjects were placed on a quarterly maintenance schedule. No differences were found between the mean baseline and 24-month measures for all dependent variables at test or control sites.
This study determined the effect of different light exposure times on the polymerization of three composite resins used as cements (Heliosit, Visio-Fil, and Dual) through various thicknesses and shades of two preprocessed composite resins (Isosit and Visio-Gem). The Knoop hardness of the surface of the luting resin was measured after polymerization and selected samples were remeasured at 24 hours to evaluate continued cure. Results indicated that polymerization of light-activated composite resin luting agents cannot predictably be accomplished through a restoration exceeding 2 mm in thickness using a light exposure of 90 seconds or less. The combined chemical and light-activated cure of Dual cement recorded the highest percentage of acceptable hardness values.
This study compared the dimensional change of simulated processed denture bases after relining with three resins. Thirty simulated denture bases 1.5 to 2 mm thick were processed from Lucitone 199 resin following the manufacturer's instructions using the long-cure method. Ten bases were relined with Lucitone 199 (long-cure), 10 were relined with Triad resin, and 10 were relined with Accelar 20 resin. The relined bases were processed on a metal die using a reline jig, and three measurements (from distobuccal flange to distobuccal flange) were made with a traveling microscope immediately before and after relining. Each relined simulated denture base showed a significant dimensional shrinkage after processing. The mean dimensional change values of the Triad resin relined bases were significantly greater than those of the other two resin relined bases. All of the dimensional change values, however, would probably be insignificant in a clinical situation.
Ten specimens each of (1) Lucitone 199, short- and long-cured, (2) Accelar 20, and (3) Triad materials were broken using a 3-point load on an Instron Universal testing machine after processing and air drying. Five specimens of each resin also were broken after storage in deionized distilled water at 37 degrees C for 30, 60, and 90 days. Triad material demonstrated the lowest transverse strengths of all three materials overall. However, Triad material was unaffected by water storage. The other resins all showed decreased strengths with water storage.
This study investigated the effect of connector design, rigid or nonrigid, on cement retention in a combined implant and natural tooth-supported fixed partial denture. A prepared natural tooth was placed in a Plexiglas block in a manner that it could move approximately the same as a healthy premolar. An endosseous implant was placed in the block so that it was immobile. Joining the prepared tooth and implant was a fixed partial denture that could be made rigid or nonrigid. The natural tooth retainer was cemented to the prepared tooth, and the implant retainer was affixed to the implant fixture with a gold screw. One year of stress was applied to the fixed partial denture by a force simulation machine. Twenty randomly ordered tests were completed, 10 of each connector design. Retentive values for the cemented retainers were recorded and statistically compared by use of Student's independent t test. No significant difference in cement retentive strength between designs was found (p less than 0.05).