Browsing by Author "Swartz, Marjorie L."

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    Attachment of Anterior Tooth Fragments
    (1985) Dean, Jeffrey A.; Swartz, Marjorie L.; Avery, David; Barton, Paul; Klein, Arthur; Phillips, Ralph
    This investigation examined the relationships of preparation and resin material types in the reattachment of fractured anterior tooth fragments. A total of 44 extracted maxillary central incisors were tested. Statistical analysis revealed that no-handpiece preparation was as retentive as a 45° circumferential bevel (p <.01). In addition, the light-cured resin proved as retentive as did the chemically-cured resin (p<.01). Also examined was the effect of the initial fracture angle on retention of the fragment after reluting. Teeth fractured with an angle sloping cervically in a lingual-to-facial direction when viewed proximally were more retentive than other types of fractures when subjected to a lingually directed force from the labial (p L.OS).
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    A Comparison of Frictional Forces During Simulated Cuspid Retraction on a Continuous Edgewise Archwire
    (1982) Allai, W. Wesley; Garner, LaForrest D.; Sondhi, Anoop; Shanks, James C.; Swartz, Marjorie L.; Barton, Paul
    This investigation was designed to compare the force (grams) required to overcome a simulated cuspid retraction assembly capable of three dimensional control during the retraction process. It was hypothesized that a significant difference in the mean retraction values exists between the newer orthodontic alloys of Nitinol, Beta-Titanium, as well as Stainless Steel. One hundred eighty bracket and archwire combinations were examined as follows: Sample # Wire Cross-section Wire Material 30 .016”x.022” Stainless Steel 30 .017”x.025” ” 30 .016”x.022” Nitinol 30 .017”x.025” ” 30 .016”x.022 Beta-Titanium (TMA) 30 .017”x.025” ” A statistically significant difference was shown to exist between all six groups examined regarding the variables of wire size and wire material. The statistical analysis revealed that increasing rectangular archwire cross-sectional size from .016"x.022" to .017"x.025” rectangular wire when simulating canine retraction using an .018" slotted Lewis bracket will lead to significantly greater functional forces. The analysis of wire materials indicated that a significant difference (p=.01) exists between rectangular Beta-Titanium (TMA), Nitinol, and stainless steel during simulated cuspid retraction utilizing a narrow .018" Lewis bracket ligated with A-lastik ligatures. The least frictional force was observed with the .016"x.022" stainless steel test cells. The largest frictional force was found in the .017”'x.025" Beta-Titanium retraction specimens. Nitinol revealed force data intermediate between stainless steel and Beta-Titanium. The maximum resistance assembly developed 2.3 times the minimum frictional force observed. The mean grams of frictional force within these test cells ranged from 55.03 grams for the .016"x.022" retraction assembly to 132.68 grams for the .017"x.025" Beta-Titanium assembly. A topographical scanning electron microscope survey of the brackets and archwires utilized was included to provide qualitative insights into the quantitative results described.
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    Effect of a stable 30 per cent stannous fluoride solution on recurrent caries around amalgam restorations
    (1968) Alexander, William Everett, 1938-; Swartz, Marjorie L.; Garner, La Forrest Dean, 1933-; Shafer, William G.
    This was a study to evaluate the effectiveness of a stable 30 per cent stannous fluoride solution on recurrent caries around the margins of amalgam restorations. Two hundred ninety deciduous and permanent teeth were restored in 34 children, ages six to nine years. Cavity preparations were treated with either stable 30 per cent stannous fluoride solution or a placebo solution (double blind technique) prior to the placement of amalgam restorations. A comprehensive coded system was used to record the description and position of conditions associated with recurrent caries after a one-year period. Children receiving the stannous fluoride treatment experienced a 58.9 per cent reduction in recurrent caries when compared to the control children. The children receiving the stannous fluoride treatment showed a 60.7 and 46.7 per cent reduction in recurrent carious lesions in permanent and deciduous teeth, respectively, when compared to the control children. The reduction in recurrent caries was attributed to the anticariogenic effect of the stannous fluoride treatment. Conditions associated with recurrent caries were mainly inadequate extension in fissures and grooves, overextension of the cavity preparation, marginal fractures of enamel and amalgam, marginal excess, and deterioration of the amalgam margin. Recurrent caries around the margins of restorations appeared to depend on (1) the caries susceptibility of the adjacent tooth structure,(2) the extension of the cavity preparation, and (3) the condition of the amalgam-enamel margin.
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    Fluoridated Orthodontic Adhesives' Effect on Enamel Fluoride Content and Demineralization
    (1995) Lampros, Penny Lynn; Moore, B. Keith; Arbuckle, Gordon R.; Katona, Thomas R.; Shanks, James C.; Swartz, Marjorie L.; Zitterbart, Paul A.
    Orthodontists are concerned about the high incidence of demineralization and decalcification around appliances. The orthodontic appliances diminish the self-cleansing mechanisms of the oral cavity, and in essence, act as traps for plaque and other debris that often lead to decalcification of the surrounding enamel. Fluoride containing dental restorative cements have been shown to reduce the incidence of secondary caries. The purpose of this study was to compare two fluoride containing orthodontic resin adhesives (a commercial, Phase II F, and an Experimental Adhesive) with a commercial nonfluoridated resin adhesive (Phase II). The resins were compared with respect to fluoride release in water over a 30 day period, hardness, and their effects on enamel fluoride content and enamel demineralization. Resin discs were made from the two fluoridated adhesives and placed in glass distilled water. Fluoride ion concentrations of the water were measured daily, and the accumulated concentrations were calculated for 30 days. Hardness discs were constructed from each adhesive, and Knoop hardness was measured after one hour, one day and one week. Finally, orthodontic brackets were bonded to bovine enamel discs, and two weeks after cementation of the brackets, the specimens were demineralized, and the adjacent enamel was biopsied for fluoride content. Those same specimens were sectioned longitudinally through the bracket and then stained with Rhodamin B. Areas of demineralization extending 500 μm from the bracket edge were measured by a confocal microscope. Depth of demineralization was measured at 250 μm intervals up to 1000 μm. The Experimental Adhesive released fluoride at a significantly higher rate over 30 days than did Phase 11 F. None of the three materials demonstrated any dramatic change in hardness after one week in water. Enamel exposed to the Experimental Adhesive had the highest fluoride content followed by that associated with Phase II F. The lowest fluoride content was found in the nonfluoridated Phase 11 adhesive. The extent of enamel demineralization, in area and depth, was inversely related to the fluoride pattern, although these differences were not statistically significant. A definite trend was noted for increased fluoride content and decreased demineralization of enamel due to increased fluoride released by the Experimental Adhesive.
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    A laboratory comparison of the adhesion of unfilled and composite resins to acid etched enamel
    (1973) Aubuchon, Robert W. (Robert Wayne), 1946-; Starkey, Paul E.; Swartz, Marjorie L.; Koerber, Leonard G.; Barton, Paul; Roche, James R., 1924-
    The purpose of this laboratory study was to determine if the bond strengths of composite resins and unfilled resins was affected similarly when applied to enamel surfaces which had been previously etched with 50 per cent phosphoric acid. The test specimens were subjected to 24 hours, 30 days, and 6 months storage in water and then subjected to temperature stress cycling and intermittent tensile stress cycling. A tensile test was used to measure the bond strengths of the composite resins (Adaptic and HL-72) and the unfilled resin (Sevriton). The following results were obtained: (1) Pretreating the enamel surface with 50 per cent phosphoric acid for 60 seconds significantly increased the bond strength of composite resins; (2) when placed on acid etched enamel, there was no significant difference in initial bond strengths obtained for the Adaptic and unfilled Sevriton resins; (3) with prolonged water storage, the Adaptic composite resins developed significant loss of bond strength when compared to the unfilled Sevriton resins and the composite HL-72 resins; (4) when Adaptic resins and the HL-72 resin specimens were compared, there was no significant difference in initial bond strengths but the HL-72 specimens were less affected by storage time. Ca45 was used to assess the marginal seal of Adaptic, HL-72, and Sevriton in acid etched and non-etched Class V restorations. One-half of the specimens were thermal cycled 2500 times and stored in water for one week. Control specimens were tested at the end of one week without the thermal cycle. On the basis of these results, it was concluded that acid etching enhances the marginal seal of both composite and unfilled resins. Both composite and unfilled resins experienced increased marginal leakage when the acid etch preparations were thermal cycled, but there were no observable difference in the marginal seal of unfilled resins and composite resins when placed in acid etched restorations.
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    A Study of Microleakage in Orthodontic Direct Bonding Adhesive Systems
    (1976-06) Ackerman, Gerald Lee; Garner, LaForrest D.; Shanks, James C., Jr.; Barton, Paul; Dickey, David M.; Swartz, Marjorie L.
    If orthodontic direct bonding adhesives are to be successful, they must withstand the destructive influences of the oral environment and form a durable bond with enamel. Investigators have noted that moisture may be the greatest deterrent to an adhesive bond and water may have the ability to penetrate the adhesive-enamel interface, destroying this bond. An in vitro investigation was undertaken to determine whether moisture and other oral debris can penetrate this adhesive-enamel interface. Four commercially available orthodontic direct bonding systems were tested for microleakage using radioisotope45 calcium chloride (45Ca). Adhesives tested included Orthomite IIS, Directon, Unitek, and Genie. Polycarbonate brackets were bonded to freshly extracted human premolar teeth using the respective adhesive systems. Specimens were stored in 37.5°c water baths for periods of thirty days and ninety days before being tested. All specimens were thermal cycled 2500 cycles to provide a more heroic test. The thermal stressing was carried out at 15°c and 45°c with a 30 second dwell at each temperature. A total of eighty specimens were evaluated. The results of this study suggest that two of the orthodontic adhesives evaluated are susceptible to amounts of microleakage. Storage in water did affect the rate of leakage among the specimens. Generally, more specimens in the groups tested at ninety days showed leakage than at the thirty-day testing period. This study suggests that orthodontic adhesives may be susceptible to microleakage and that this may present problems clinically. However, long-term, well controlled investigations must be undertaken before more definite conclusions can be drawn concerning the effect on bond strength and enamel integrity.