IU Indianapolis ScholarWorks :: Browsing by Subject "Dental Materials"

Browsing by Subject "Dental Materials"

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An Analysis of the Fatigue Resistance of Beta Titanium and the Effect of Spot-Welding Upon the Fatigue Resistance of this Alloy
(1984) Wong, Michael B.; Garner, LaForrest; Baldwin, James; Moore, Keith; Barton, Paul; Shanks, James
This investigation was designed to establish a fatigue curve for beta titanium, determine the effect of spot-welding upon the fatigue resistance of this alloy, and provide qualitative observations about surface characteristics of different batches of TMA in relation to their fatigue lives. Rectangular .016" x .022" 1MA was evaluated. Twelve specimens in each group were tested, making the total sample size 108. The wire samples were evaluated using a cantilever bend test in which specimens were stressed cyclically at varying deflections. Two welded groups were also tested. An auxiliary .016" x .022" TMA was welded to a main test segment of TMA with the .016" side against the opposing .016" side. The weld overlap varied at 25% for one group and 50% for the other. These specimens were stressed at the area adjacent to the weld. One specimen from each group was viewed under the scanning electron microscope to evaluate the fractured area. Specimens from three different batches of 1MA were tested and their fatigue lives compared at .625 inch deflection. One specimen from each batch was viewed under the scanning electron microscope to evaluate its surface structure. A fatigue curve for TMA was plotted from the data. At .625 inch deflection, welding an auxiliary onto the main segment significantly decreased the fatigue resistance of the wire. However, both welded groups had comparable fatigue lives. These wire specimens fractured at some point adjacent to the welded site. Fatigue resistance differed significantly between one batch of TMA and the other two. The scanning electron micrographs of representative specimens from each batch seemed to indicate that the fatigue resistance of each batch was inversely related to its surface roughness.
A clinical evaluation of the effect of polishing procedures on the marginal breakdown of two dental amalgams
(1977) Adams, George Austin, 1949-; Koerber, Leonard G.; Avery, David R.; Barton, Paul; Osborne, John William, 1939-
The investigation was undertaken to determine the effects of the polishing and finishing of dental amalgam in relation to its marginal breakdown. The study was also conducted to make a clinical comparison of the marginal integrity of Dispersalloy restorations as compared to Twentieth Century Fine Cut Alloy restorations in both the polished and unpolished state. Forty patients with a total of 131 Class I amalgam restorations were used as the study group. The two alloy systems and polish or unpolish techniques were selected from a random table. Photographic evaluation of the restorations was used to judge the degree of marginal breakdown. The results of the study at the one-year evaluation show two main findings: (1) the Dispersalloy restorations showed less marginal breakdown than the Twentieth Century Fine Cut Alloy restorations, and (2) there was no significant difference between the polished and unpolished restorations overall.
A clinical investigation of the general disintegration and strength characteristics of four temporary filling materials
(1963) Bastawi, Aly Eloui A., 1928-
The purpose of this study was to evaluate clinically, the general disintegration, gross fracture, marginal breakdown, and surface texture in Class I and Class II restorations of four temporary filling materials having widely varying physical properties. They were zinc oxide-eugenol (Temrex), zinc oxide-rosin eugenol (Caulk’s), zinc phosphate cement (Tenacin), and silico-phosphate cement (Kryptex). Powder-liquid ratios and all manipulative procedures for each of the four materials were standardized. Compressive strength, solubility and abrasion resistance tests were carried out in the laboratory on the same standardized mixes used in the clinical part. A total of 137 standardized cavities were prepared in deciduous and permanent teeth of 37 children and restored with the four materials in an effort to equalize the distribution between the four quadrants. Rubber base impressions were taken as permanent records for evaluation at the one week, one month and three months observation visits. Zinc oxide-rosin eugenol (Caulk) exhibited the least resistance to disintegration and the roughest surface while the zinc oxide eugenol (Temrex) exhibited considerably more resistance and the smoothest surface. Zinc phosphate showed the greatest resistance to disintegration. Silico-phosphate cement exhibited the same behavior in Class I restorations but showed higher failure in Class II restorations due to fractures. Zinc phosphate exhibited smoother surface than the silico-phosphate cement. There was no correlation between in vitro solubility and clinical disintegration. Compressive strength seemed to be related to the general durability of the materials.
A composite resin versus an amalgam: a study of certain properties and the design and initiation of a clinical investigation
(1971) Avery, David Roger; Gilmore, H. William (Homer William); Van Huysen, Grant; Garner, La Forrest Dean, 1933-
Certain properties of a representative composite material were evaluated by in vitro testing and compared to those of other types of restorative materials. A clinical study designed to evaluate the performance of the composite material as compared to amalgam for Class II restorations was initiated and one-year results are reported. Laboratory tests for abrasion resistance, hardness, marginal leakage, strength, color stability, staining characteristics, solubility, and water sorption were conducted. The clinical study is still in progress but the results after one year indicated that the composite resin test restorations, as well as the amalgam control restorations, were generally satisfactory. In overall clinical performance neither material was superior to the other. The amalgam restorations received a superior rating for anatomic form while the composite restorations were superior in terms of marginal adaptation. No clinical evidence of recurrent caries, associated with any of the restorations, was detected. Surface discoloration was a significant finding on the composite restorations, but it was confined to proximal areas and may be related to the difficulty of cleaning these areas with a toothbrush. No conclusions can yet be made regarding the long-term clinical performance of the composite resin used in this investigation as a Class II restorative material.
Composite versus amalgam: A three-year clinical study in posterior primary teeth
(1984) Nelson, Gayle V.
Clinical studies on composite resins in Class II Resotrations place in adults indicate that wear is the predominant problem. However, little has been published on the use of composites for such restorations in primary teeth. The purpose of this study was to compare amalgam to composite resins in such restorations. Two composite resins (Adaptic and Radio-opaque Adaptic) served as the Experiemental material and amalgam, (Dispersalloy) was the control . One operator placed 57 sets, one restoration of each of the three materials per set, in 50 patients at the Riley Children's Hospital in Indianapolis. Evaluations were made at baseline, six months, one year, two years, and three years using the Ryge-USPHS criteria and by means of casts poured from elastomeric impressions. Results of the Ryge-USPHS criteria indicated no wear or color change of the composites after two years (p=N.S.). However, of the 49 sets that returned at one year, two composites had caries around the restoration. This particular observation was monitored at the three-year time interval and found not to increase around any other composite restorations. Composite restorations in posterior primary teeth compared equally to amalgam (Dispersalloy) for the first two years of the project. The loss of anatomic form was significant after three years (p=.05).
Effect of interim fixed prosthodontics materials and flowable composite resins on polymerization of polyvinyl siloxane impressions
(2017) Alsayed, Hussain D.; Platt, Jeffrey A.; Levon, John A.; Haug, Steven P.; Brown, David T.
Effect of post-irradiation polymerization on selected mechanical properties of six direct resins
(J-STAGE, 2022) Sochacki, Sabrina; Karczewski, Ashley; Platt, Jeffrey; Roberts, Howard W.; Biomedical Sciences and Comprehensive Care, School of Dentistry
This study evaluated the post-irradiation mechanical property development of six resin composite-based restorative materials from the same manufacturer starting at 1 h post irradiation, followed by 24 h, 1 week, and 1 month after fabrication. Samples were stored in 0.2M phosphate buffered saline until testing. Flexural strength, flexural modulus, flexural toughness, modulus of resiliency, fracture toughness, and surface microhardness were performed at each time interval. Mean data was analyzed by Kruskal Wallis and Dunn's post hoc testing at a 95% level of confidence (α=0.05). Results were material specific but overall, all resin composite material mechanical properties were found to be immature at 1 h after polymerization as compared to that observed at 24 h. It may be prudent that clinicians advise patients, especially those receiving complex posterior composite restorations, to guard against overly stressing these restorations during the first 24 h.
Effect of Silica Filler on the Mechanical Properties of Silicone Maxillofacial Prothesis
(2014) Yeh, Hsin-Chi; Chu, Tien-Min Gabriel; Ando, Masatoshi; Brown, David T.; Bottino, Marco C.; Levon, John A.
Background: VST-50 (a room temperature-vulcanizing silicone (RTV) by Factor II Inc.) has long been proposed as a potential alternative material for MDX4-4210, another RTV by Dow Corning Corp. and the current material of choice for maxillofacial prosthesis. Though VST-50 has similar chemistry and flexibility as MDX4-4210, its mechanical properties is still too low for it to be used in the clinic. An improvement in the mechanical property of VST-50 is a critical step to bring the material to clinical application. Objective: To investigate the effect of AEROSIL® R 812S (colloid silica) addition on the mechanical properties of VST-50 and compared to that of MDX4-4210. Methods: The VST-50 was mixed with AEROSIL® R 812S at 2 or 4 parts per hundred parts of rubber. That material was mixed with the catalyst under vacuum. The mixture was poured onto a machined plastic mold to produce a silicone sheet 3.0 ± 0.2 mm thick. All samples were prepared by manufacturer recommended method. Testing samples were prepared and tested following ISO 37 for tensile strength, ASTM D624 for tear strength and ASTM D2240 for shore A hardness test. One way ANOVA was used to compare the groups (Alpha=0.05). Result: Significant differences (P<0.001) were found between MDX4-4210 and modified VST-50 groups. The mean value of tensile strength, tear strength and hardness of VST-50 (4phr colloid silica) were 7.43(MPa), 34.82(N/mm) and 40.4 respectively, compared to MDX4-4210 were 3.67(MPa), 5.48(N/mm) and 31.5, respectively. Conclusion: Modified VST-50 with 4phr silica revealed improved mechanical properties to use as a maxillofacial prosthetic silicone elastomer.
Effectiveness of universal adhesive bonding agents on the shear bond strength to lithium disilicate ceramics
(2015) AlRabiah, Mohammed A.; Platt, Jeffery A.; Levon, John A.; Brown, David T.; Chu, Tien-Min Gabriel; Bottino, Marco C.
Background: All-ceramic restorations have excellent esthetic outcomes compared with other restorative materials. Lithium disilicate is classified as one of many silica-based all-ceramic materials. Currently, companies have provided single-step adhesives, known as universal adhesives, compatible with different restorative materials including lithium disilicate. Many studies have reported greater bond strengths when using a silane to treat the lithium disilicate before applying the bonding agent. Moreover, few studies were published comparing the bond strength when using the universal adhesive alone. Purpose: The objective of this study was to evaluate and compare shear bond strength of three universal adhesives to lithium disilicate ceramic restorative material. Materials and Methods: Three universal adhesive bonding agents were selected from commercially available adhesives. 408 IPS e.max CAD ceramic discs were processed, fired, and etched for 20s. The specimens were divided into six groups. The first three groups used the universal adhesive directly. The remaining three groups were treated with silane. Then, a composite resin cylinder was placed on top of the adhesive using a bonding jig. Each group was subdivided into four equal subgroups (n = 17), subjected to different aging simulation procedures: 24 h, one month with 5000 thermocycles, two months with 5000 cycles, and three months with 5000 cycles. Then, specimens were debonded using shear force by a universal testing machine (MTS). Results: Shear bond strength was greater with silane than without silane (p < 0.0001), regardless of the levels of adhesive or time. Shear bond strength was significantly greater at 24h and 1m than at 2m (p < 0.0001) or 3m (p < 0.0001) regardless of the adhesive or the presence of silane. Debonded specimens were examined under a stereomicroscope at X45 magnification to evaluate the fracture pattern. SEM was used to prove the results were considered as mixed failure. Conclusion: The optimal bonds to lithium disilicate are achieved by application of silane prior to application of a universal adhesive. Although the constituent silane in the universal adhesive was not effective in optimizing the resin to ceramic bond, silane should always be applied to lithium disilicate prior to bonding.
Effects of sealant conditioners on occlusal surface bacteria: a clinical study
(1976) Johns, Michael R. (Michael Reed), 1946-
This clinical study evaluated the effects of conditioning agents for pit and fissure sealants on the bacteria present in occlusal grooves and fissures in permanent molars. The conditioning agents, 50 percent phosphoric acid and 50 percent phosphoric acid attenuated with 7 percent zinc oxide, with distilled sterile water being used as a control, were compared for their ability to kill bacteria in carious occlusal lesions. Eighty-six teeth from children eight to twelve years of age were conditioned with one of the randomly assigned agents using a blind method to prevent bias. The teeth were then cultured with a method that measured results as to growth or no growth after incubation. The culturing was done at both the occlusal surface and the depth of the lesion. A chi square test demonstrated that there were no significant differences between the conditioners on either the occlusal or depth of the lesion cultures (x2 = .31, df = 2, a = .05). The two conditioners did not totally kill the bacteria in occlusal lesions often enough to justify their use as bactericidal agents before sealants are applied.

Browsing by Subject "Dental Materials"

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