Biomedical subjects
Publications and source records attributed to E J Swift.
Although the use of cavity varnishes with composite resins has traditionally been discouraged, several "resin-compatible" varnishes are currently available. This in vitro study evaluated the effects of resin-compatible cavity varnishes on a hybrid composite resin. The results of the study indicate that these varnishes soften the composite resin in contact with varnished dentin.
This study evaluated the effectiveness of air abrasion (sandblasting), hydrofluoric acid (HF) etching, and acidulated phosphate fluoride (APF) for composite repair. Five different composites (three hybrids, one small-particle, and one microfill) were used to test the effects of different compositions and particle sizes. A phosphonate resin bonding agent was used for all repair procedures. In general, air abrasion provided the strongest repairs, approximately 60% of cohesive strength. The effect of HF varied with different composites, either improving or reducing the repair strength. APF gave the lowest interfacial bond strengths for all composites except the microfill.
This in vitro study tested the shear bond strengths of nine third-generation dentin bonding systems. All of these systems had higher bond strengths than the control, a second-generation agent. Amalgambond and All-Bond had the strongest bonds to dentin, 23.3 +/- 5.7 and 19.3 +/- 5.6 MPa, respectively. Clearfil Photo Bond and Prisma Universal Bond 3 had intermediate bond strengths (approximately 13 MPa). Gluma, PowerBond, Scotchbond 2, Tenure, and XR-Bond all had mean shear bond strengths of less than 8 MPa.
Composite can be cured extraorally to fabricate indirect or direct/indirect restorations. These restorations are bonded to the tooth with a dual-cure resin cement. This study evaluated various methods for treating the surface of an indirect glass-filled composite to improve its bond to enamel. The methods tested were air abrasion (sandblasting), hydrofluoric (HF) acid etching, silanation, and combinations of these techniques. Shear bond strengths were measured for thermocycled and non-thermocycled specimens. Air abrasion, followed by silanation, provided the strongest and most consistent bonds. Etching with 9.6% HF gel decreased the bond strengths obtained by air abrasion. HF alone produced the weakest bonds, with most failures occurring adhesively between the indirect composite and the resin cement.
This article describes a simple but effective method of bleaching single vital discolored teeth. The patient applies a viscous 10% carbamide peroxide gel in a plastic mouth-guard designed to confine the gel only to the discolored tooth. This method has been effective for lightening vital teeth with calcified pulpal spaces.
This in vitro study tested the shear bond strengths of the Scotchbond Multi-Purpose adhesive system to moist and dry enamel and dentin. After the tooth was etched, the surface was either dried with compressed air or blotted with tissue paper, leaving the surface visibly moist. Primer and adhesive were applied according to the manufacturer's directions. Resin composite posts were applied, and the specimens were thermocycled. Shear bond strengths were determined using an Instron universal testing machine. For both enamel and dentin, mean shear bond strengths were higher when the surface was left visibly moist after etching. Bond strengths to moist and dry dentin were 21.8 and 17.8 MPa, respectively. Enamel bond strengths were slightly lower, with values of 17.0 and 14.2 MPa to moist and dry enamel, respectively.
Internal bleaching is frequently used to treat discolorations of endodontically treated teeth, and home bleaching of stained vital teeth has also become popular. This article describes a case in which carbamide peroxide home bleaching was used to enhance the appearance of an internally bleached, endodontically treated tooth.
A number of home bleaching products have recently been introduced. This in vitro study evaluated the effect of three representative bleaching products on the microhardness and surface texture of hybrid and microfilled composite resins. Scanning electron microscopic examination revealed cracking of the microfilled specimens treated with carbamide peroxide gels (Proxigel and White & Brite). White & Brite also caused slight roughening of the hybrid composite resin. Microhardness tests indicated that the treated composite resins became somewhat softer. However, the only statistically significant softening was associated with White & Brite.
Some clinicians now advocate dentinal etching to eliminate microleakage around composite resin margins. This study evaluated the "Kanca technique" and three commercial dentinal adhesives, including Clearfil Photo Bond, which uses phosphoric acid to etch dentin. The Kanca technique and Tenure were the most effective systems tested. However, none of the bonding systems completely eliminated microleakage. Total sealing of dentinal margins is not predictable with current adhesives and composite resins.
This paper describes a clinical case in which a combination bleaching technique was used to improve the appearance of the patient's discolored anterior teeth. Enamel microabrasion was used first to remove superficial fluorosis stains. A home bleaching regimen was then used to lighten the overall shade of the teeth, which had appeared more yellow after microabrasion.
This study investigated the sealing properties of Cavalite light-activated base material in conjunction with various dentin bonding agents. Thirty extracted molars were selected and cleaned. Slot preparations with standard dimensions were made. The prepared cavities were filled with Cavalite material after application of the dentin bonding agents Gluma, Prisma Universal Bond, Scotchbond 2, and Tenure. Samples were thermocycled for 180 cycles between 3 degrees C and 60 degrees C, then immersed in 0.05% crystal violet solution for 2 hours. The samples were embedded in clear casting resin, sectioned, and examined with a light microscope. Results indicated that Cavalite material used alone, without a dentin bonding agent, allowed the greatest degree of dye penetration. Cavalite material with Tenure bonding agent had the lowest degree of leakage. Cavalite material used with Scotchbond 2, Gluma, or Prisma Universal Bond bonding agents allowed an intermediate degree of dye penetration. According to an analysis of variance, however, there was no statistical difference in the effects of Tenure, Scotchbond 2, and Gluma bonding agents.
Decalcification around brackets is sometimes observed after orthodontic treatment. Fluoride-releasing orthodontic adhesives have been developed in an attempt to reduce the frequency and severity of decalcification. This study evaluated, in vitro, a light-activated, fluoride-releasing composite resin adhesive, FluorEver OBA. The findings indicate that FluorEver OBA released small concentrations of fluoride ions over time. A mean of 2.6 ppm was released on day 1, decreasing to a mean of 0.42 ppm by day 2 and to 0.04 ppm by day 43. The clinical implications of these findings are discussed.
The purpose of this study was to determine the effects of porcelain opacity, chemical catalyst, and exposure time on polymerization of light-activated resin-composite cements. Samples of microfill and hybrid composites, with and without catalyst (i.e., dual-cure and visible-light-activated), were polymerized by exposure to visible light through porcelain discs of different opacities. Microhardness testing (KHN) was used to compare degree of cure for each material at various exposure times. Porcelain opacity did not significantly affect hardness. However, the results indicated that a chemical catalyst and prolonged curing times might be essential for clinical success.
This study evaluated the effects of a dentin bonding system and glass ionomer liner on in vitro recurrent caries around resin composite restorations in dentin. The dentin adhesive significantly reduced the size of recurrent lesions. The glass ionomer liner, applied either to the axial wall or to the cavosurface margin, provided an even greater cariostatic effect. Both the adhesive and the liner reduced the size of cavity wall lesions. In addition, zones of caries inhibition were present around 75% of restorations lined with glass ionomer cement.
In the study, scanning electronmicroscopy and x-ray microanalysis techniques were used to examine a silver-reinforced glass ionomer cement. Scanning electron microscopy was used to evaluate surface topography and microstructure. Microcracking and a bimodal pore distribution were observed. The cement consisted of unreacted glass particles surrounded by a silica gel "halo" and embeded in an organic salt matrix. Back-scattered electron microscopy and energy-dispersive spectroscopy detected discrete clusters of silver atoms within the material. Other elements, such as calcium and aluminum, were dispersed homogeneously. Wave-length dispersive spectroscopy was used to detect fluoride, which also appeared to be homogeneously distributed. Electron microscopy and x-ray microanalysis techniques could prove valuable in clarifying the microstructure and fluoride release mechanisms of glass ionomer cements. Refinement of some aspects, including sample preparation, will be necessary to obtain consistently reliable results.
Historically, invasive restorative procedures have been required to create undercuts for removable partial denture retainers where natural undercuts are lacking. Resin-bonding procedures have allowed the development of conservative, minimally invasive methods for creating undercuts. A technique using a partial-coverage porcelain laminate is described.
Plastic teeth are commonly used to help teach students who are taking preclinical courses in restorative dentistry. Unfortunately, plastic teeth do not have the texture, anatomy, and other characteristics of natural teeth. To provide more realistic clinical experience for dental students, a technique is described for mounting natural teeth in a dentoform.
Decalcification around brackets is sometimes observed following orthodontic treatment. Fluoride-releasing orthodontic adhesives have been developed and used for reduction of the frequency and severity of decalcification. This study evaluated a light-activated, fluoride-releasing resin composite adhesive, FluorEver OBA. Our findings indicate that FluorEver OBA released small concentrations of fluoride ions over time. However, the adhesive had significantly lower tensile bond strengths than a conventional composite cement. Microhardness testing indicated that the resin underneath metal orthodontic brackets was not thoroughly polymerized, which may have contributed to cohesive failures of the resin composite. Despite its lower tensile bond strength, FluorEver OBA may be indicated for cases where decalcification is expected.