Biomedical subjects

J D Eick

Publications and source records attributed to J D Eick.

At least 55 records · Page 3Linked to original sources

PubMed1994

The effects of ion sputtering on dentin and its relation to depth profiling.

Characterization of the dentin surface and the dentin/adhesive interface is fundamental to investigations concerning adhesive bonding to dentin. It has been shown that good adhesive bonding depends on both the structure and composition of the dentin surface. A combination of ion sputter etching and Auger electron spectroscopy can be used to obtain surface composition and elemental depth profiles at interfaces. This investigation was conducted to examine the changes induced in human dentin by ion sputtering under conditions commonly encountered during depth profiling. The sputtering was conducted with argon ions at 7.5 keV and an ion flux ranging from 10(18)-10(19) ions/m2s. The amount of material sputtered was calculated from profilometer measurements of the sample surface. The surface composition was monitored by Auger electron spectroscopy. The results indicate that, under these conditions, collagen was removed at a much faster rate than hydroxyapatite, causing the surface composition of dentin to change during the sputtering process. The sputter yields for hydroxyapatite and collagen were found to be 5 and 28 atoms/ion, respectively, at a sputter angle of 45 degrees. At a sputter angle of 29 degrees, the yields were 2 and 25 atoms/ion, respectively. Both the changes in composition of dentin and the measured sputter rates are in agreement with the behavior predicted by a theoretical model for two phase materials (Blaise, 1978; Blaise et al., 1978).

Acid Etching, Dental↗

PubMed1994

The effects of current dentinal adhesives on the dentinal surface.

The effects of the dentinal surface treatments from six currently available commercial dentinal adhesives are presented. The adhesives are All-Bond 2, etched and unetched, Syntac, Prisma Universal Bond 3, Scotchbond Multipurpose, Tenure Solution, and Adhesive By Choice. Unerupted third molar human teeth were sectioned and treated with the appropriate adhesive according to the manufacturer's directions. After the teeth were treated, they were processed for observation by scanning electron microscopy. Scanning-electron microscopic photomicrographs were made of each step in the process to show the effects of the constituents, including the adhesives, on the dentinal surface. For All-Bond 2, unetched, the smear layer was not removed before the primer and the adhesive were applied. The primer for Prisma Universal Bond 3 altered the smear layer by reacting with it but did not produce a large demineralized zone in the dentin. All the other adhesives did remove the smear layer before the tooth was treated with the primer and adhesive.

Acid Etching, Dental↗

PubMed1994

The effect of spiroorthocarbonate volume modifier co-monomers on the in vitro toxicology of trial non-shrinking dental epoxy co-polymers.

A major improvement in dental restoratives is possible through the development of biomaterials that do not shrink upon polymerization, hence, avoid leakage and subsequent breakdown. Polymers containing spiroorthocarbonates (SOCs) show promise in this respect, but their toxicology in copolymerized materials has not been explored. In this study, the in vitro toxicology of these materials in homopolymer form and in two trial non-shrinking epoxy co-polymers was evaluated for cytotoxicity and mutagenicity. Cytotoxicity was determined by the MTT test to measure the lethality effect on mouse L929 cells. Mutagenicity was evaluated using the Ames-Salmonella Test. For comparison, commercial composite and adhesive materials as well as several other materials of current interest in dentistry were also evaluated. Epoxy resin samples containing 5% of either T/T SOC or Dp SOC reduced the cytotoxicity (TC50) from approximately 400 to 800 micrograms/200 microliters. The epoxy-spiro copolymers had more favorable TC50 values than the commercial product Super-Bond. They showed TC50 values on the order of 35% greater than Super-Bond and 45% less than Scotchbond 2, the latter two being materials currently used in the clinic. These two comparatives demonstrated dose response curves with lower doses at maximum cell kill values than the spiro materials. The epoxy formulations all showed weak mutagenesis, but this is attributed to the epoxy formulation and not the SOCs. Although considerable toxicology is yet be conducted, these in vitro results suggest that biocompatible copolymer formulations for spiroorthocarbonates are a developmental reality.

Adhesives↗

PubMed1994

Shear bond strength and scanning electron microscopic observation of six current dentinal adhesives.

This paper presents shear bond strength data and scanning electron photo micrographs of six dentinal adhesives: All-Bond 2, etched and unetched; Syntac; Prisma Universal Bond 3; Scotchbond Multi-Purpose; Tenure Solution; and Adhesive By Choice. The methods used in tooth treatment and scanning electron microscopic observation were identical to those used in previous studies. This permitted comparisons among a total of 13 dentinal adhesives (seven from previous studies), all treated under the same experimental conditions and all currently available to the practitioner. Scanning electron micrographs showed the types of failures that occurred when the composite resin was fractured from the dentin. Most of the fractures were adhesive, with the exception of Scotchbond Multi-Purpose, which had many cohesive failures in the dentin or the composite resin. There was no significant difference among any of the shear bond strength values with the exception of Scotchbond Multi-Purpose, which was significantly stronger than the other five adhesives studied.

Analysis of Variance↗

PubMed1993

Auger electron spectroscopy of dentin: elemental quantification and the effects of electron and ion bombardment.

Auger electron spectroscopy was used in this investigation to quantify the elemental composition of various dentin surfaces. The surfaces included the "smeared layer," produced by abrasion, as well as surfaces prepared by fracturing in vacuum and in air. Quantification was aided by spectra obtained from standard samples of the two main components of dentin, hydroxyapatite, and collagen. Experimental conditions were found whereby the samples could be analyzed without conductive coatings. Ion sputter etch rates were measured for dentin, hydroxyapatite, and collagen. Under the conditions used here, it was observed that collagen etched at a rate approximately five times greater than hydroxyapatite. Auger spectra of the sputtered surfaces indicated significant ion beam-induced sample changes in collagen and dentin; no significant changes were found with hydroxyapatite. The results of this investigation demonstrate that Auger electron spectroscopy can be used to characterize dentinal surfaces and that ion sputtering can cause changes in the surface composition of dentin.

Collagen↗

PubMed1993

Properties of expanding SOC/epoxy copolymers for dental use in dental composites.

The objective of this work was to develop copolymers of alicyclic spiroorthocarbonates (SOCs) and epoxies that would yield hard non-shrinking matrix resins suitable for formulating dental composites. Several reactant ratio combinations of a four-component SOC/epoxy comonomer system were developed that demonstrated a copolymer expansion of between 0.1 and 0.8% on polymerization. The physical properties of tensile strength (29-48 MPa), water solubility of less than 5 microgram/mm(3), and water sorption of less than 50 microgram/mm(3) for the copolymer containing 5% SOC suggest that these materials have potential as matrix resins for dental composites.

Carbonates↗

PubMed1993

Effects of air-powder polishing on the bond strength of orthodontic bracket adhesive systems.

PURPOSE: The purpose of this in vitro investigation was to evaluate the effects of air-powder polishing on the shear bond strength of two adhesive systems used for direct orthodontic bracket bonding. METHODS: Ninety-six third molar teeth were randomly assigned to be bonded with metal brackets using either a no-mix (System 1+) or a two-paste (Concise) orthodontic adhesive resin. Twelve samples in each test group were air-powder polished for either 0, 15, 30, or 60 seconds. The shear bond strength was determined for each bracket using the Instron. Scanning electron microscopy determined bond fracture patterns of tested samples. RESULTS: Mean shear bond strength values from baseline to 60 seconds varied from 22.9+/-1.9 megapascal units (MPa) to 18.2+/-4.1 MPa for Concise and from 15.5+/-2.1 MPa to 14.6+/-1.9 MPa for System 1+. A two-factor analysis of variance showed air-powder polishing significantly affected the mean shear bond strength of one adhesive. Results showed a significant decrease (p < or = .05) in the mean shear bond strength of the Concise adhesive at 60 seconds of air-powder polishing when compared to the 0-, 15-, and 30-second treatments. No significant within group time effect of air-powder polishing was found for System 1+. Differences in the fracture pattern of the Concise 60-second air-powder polishing group may account for the decrease in mean bond strength seen after treatment. CONCLUSION: Although in vitro results showed decreased bond strength for Concise, these values were well above the minimum values needed for successful bonding. Therefore, use of air-powder polishing on orthodontic bracket adhesive systems does not appear to be contraindicated.

Bisphenol A-Glycidyl Methacrylate↗

PubMed1993

Photoelastic stress analysis of natural teeth and three osseointegrated implant designs.

This study used photoelastic stress analysis to compare the location and magnitude of periradicular stresses created by load application directed through two anatomically different natural teeth and three different implant designs. Also studied was the contribution made by the periodontal ligament in the transfer of these stresses. Within the limits of this study, results suggest that the abutment structures with the greatest amount of periodontal support tend to distribute stresses in the most favorable manner. Also, the conical shape of the tooth root, with its large cervical area, has a distinctly positive effect on stress distribution.

Birefringence↗

PubMed1993

The dentinal surface: its influence on dentinal adhesion. Part III.

This final paper in a series of three uses transmission and scanning electron microscopy to compare the category III dentinal adhesive systems--those with shear bond strength values near or exceeding 17 MPa. Contemporary commercial dentinal adhesive systems such as Superbond and Scotchbond Multi-Purpose, chosen for their varied chemical pretreatments, are contrasted; a contemporary commercial system (Prisma Universal Bond 3) with characteristics of category I and II dentinal adhesives is also included for comparison. The shear bond strength values attained with most category III systems are high enough to cause cohesive failure of the dentin during bond strength testing. This result is attributed to a combination of factors that include effective wetting and penetration of the prepared dentinal surface as well as a tendency to leave collagen fibers at the adhesive-dentin interface in an apparently structurally intact state.

Boron Compounds↗

PubMed1993

Adhesives and nonshrinking dental resins of the future.

Much attention has been directed toward producing dentinal adhesives that withstand the forces involved during polymerization shrinkage of composite resins. Studies have shown that an effective dentin-adhesive bond depends on the wetting and penetration characteristics of the dentinal adhesive system and the reactivity of the treated dentinal surface. The structure of the collagen in the demineralized dentinal layer also seems to influence the behavior of the bond. Adhesive systems that do not completely denature the fibrous collagen and leave interwoven banded collagen in the demineralized layer produce superior bond strengths (greater than 20 MPa). Other research efforts seek to develop a nonshrinking high-performance polymer for use as a matrix material for dental composite resins. Spiroorthocarbonates that expand during polymerization have been developed. In combination with a three-component epoxy comonomer, matrix resins have been produced that expand during polymerization and whose mechanical properties, water sorption, solubility, and degree of polymerization are acceptable for dental use. Further developments of nonshrinking composite resins and improved dentinal adhesives will greatly increase the longevity of 21st-century composite resin restorations and should significantly ease clinical placement.

Adhesives↗

PubMed1992

Effect of two dentin bonding agents on microleakage in two different cavity designs.

Studies have shown that cavity design and dentinal bonding agents can affect composite resin microleakage. This study compared the microleakage at cementum-dentin margins of box- and Vshaped preparations restored with two different bonding agents. Twenty freshly extracted, human third molars were prepared with one box-shaped and one V-shaped preparation on the mesial or distal surface. Occlusal margins were terminated in etched enamel and gingival margins were in cementum-dentin. There was no statistically significant difference (p greater than 0.05) between Dual Cure Scotchbond and Scotchbond 2 samples restored in the box-shaped preparations, but Scotchbond 2 had statistically significantly less microleakage (p less than 0.05) than Dual Cure adhesive in V-shaped preparations. The sealing of dentinal bonding agents varied in different cavity designs.

Adhesives↗

PubMed1992

Accuracy of one-step versus two-step putty wash addition silicone impression technique.

This study compared the accuracy of one-step putty wash with two-step putty wash impression techniques. Five addition silicone impression materials-Mirror 3 (MR), Mirror 3 Extrude (ME), Express (E), Permagum (P), and Absolute(A)--were tested. A stainless steel model containing two full-crown abutment preparations was used as the positive control. Five replications for one-step and two-step putty wash impressions of the master model were made for each test material. Accuracy of the materials was assessed by measuring six dimensions on stone dies poured from impressions of the master model. Accuracy of addition silicone impression material is affected more by material than technique. Accuracy of the putty wash one-step impression technique was not different from the putty wash two-step impression technique except at one of the six dimensions where one-step was more accurate than two-step. Mirror 3 putty wash two-step impression presented less distortion than Mirror 3 Extrude putty wash one-step or two-step impression.

Analysis of Variance↗

PubMed1992

Synthesis and polymerization of new expanding dental monomers.

The objective of this work was to develop polymeric materials that expand slightly upon polymerization and that could potentially be used as matrix resins for dental composites. A series of stereoisomeric alicyclic spiroorthocarbonates (SOC's) that expand when polymerized were synthesized. Three of these SOC racemates were analyzed: cis/cis-, cis/trans- and trans/trans-2,3,8,9-di(tetramethylene)-1,5,7,11-tetraoxaspiro[5.5] undecane. The degrees of expansion, approximately 3.9% and 3.5%, for the cis/cis and trans/trans, were determined by measuring the specific volume of the monomers and polymers in dilute solutions. This method of determining densities and subsequent calculated expansion or shrinkage was validated by duplicating the reported shrinkage of 4-tert-butylphenyl glycidyl ether, styrene, and methyl methacrylate. Based on these data and spectral data obtained using other analytical techniques, these stereoisomeric alicyclic SOC's appear to have potential as nonshrinking polymer or copolymer matrices for dental composites.

Chromatography, Gas↗

PubMed1992

Chemical characterization of the dentin/adhesive interface by Fourier transform infrared photoacoustic spectroscopy.

Irreversible bonding of composite materials to tooth structure depends on chemical as well as mechanical adhesion. The proposed bonding mechanism for several commercial dental adhesives is chemical adhesion to the dentin surface. The purpose of this in vitro investigation was to characterize the chemical nature of the surface interaction between dentin and two commercial adhesives by use of Fourier transform infrared photoacoustic spectroscopy (FTIR/PAS). The occlusal thirds of the crowns of freshly extracted, non-carious, unerupted human molars were sectioned perpendicular to the long axis. Dentin disks, 6 mm x 2 mm, were prepared from these sectioned teeth. The exposed dentin surface was treated with either Scotchbond 2, a BIS-GMA resin, or Dentin-Adhesit, a polyurethane resin. All spectra were recorded from 4000 to 400 cm-1 by use of an Analect RFX-65 FTIR spectrometer equipped with an MTEC Photoacoustics Model 200 photoacoustic cell. An initial spectrum of the dentin surface was collected. This surface was primed according to manufacturer's instructions and spectra recorded of the primed surface plus one to three layers of adhesive. By comparison of these spectra, it was possible for us to record changes in the phosphate and amide I and II bands due to surface interactions between the adhesive and the dentin. Although early results do not indicate covalent bonding between the dentin and these adhesives, this technique presents several advantages for spectroscopic evaluation of the dentin/adhesive interface.

Acrylic Resins↗

PubMed1992

Bone hole diameter as a function of drill guide length and drilling method in rigid internal fixation.

This study examines drill guide length and drilling method to see which technique produces the most accurate hole diameter. Two hundred twenty-five holes were produced in fresh porcine mandibles and then measured with a micrometer. A long guide, a short guide, and no guide were used with a drill press, a pneumatic drill, and a manual drill. Using a 2-mm drill bit, the overall average diameter was 2.03 mm and the overall range was 1.85 mm to 2.60 mm. Statistical analysis of the data indicates the drilling method and the guide length made no difference in the hole diameter at the 95% level (P = .05).

Analysis of Variance↗

PubMed1992

Smear layer--materials surface.

SEM and TEM photomicrographs were presented of the smear layer and several dentin-adhesive interfaces. It was shown that as the wetting and penetration of the dentin adhesive increased, the shear bond strength also increased. Three categories of dentin adhesives were presented. Category one included Scotchbond, Dentin Adhesit and Gluma, with shear bond strength values between 5 and 7 MPa; the second category, dentin adhesives based on Dr. Bowen's research, included Tenure and Mirage Bond, with shear bond strengths between 8 and 14 MPa; the third category included Superbond and Scotchbond 2, with shear bond strength values up to 20 MPa. Failures occurred at the interface or in the resin adhesive for materials in categories one and two; failures occurred through the dentin or composite for materials in category three.

Adhesives↗

PubMed1992

The dentinal surface: its influence on dentinal adhesion. 2.

The first paper in this series presented a categorization of dentinal adhesive systems that was organized roughly according to chronology, chemistry, and shear bond strength values. Category I dentinal adhesives demonstrate the lowest shear bond strength values, approximately 5 to 7 MPa. Category II dentinal adhesives, including experimental ferric and aluminum oxalate pretreatments and two commercial products, demonstrate shear bond strength values between 8 and 14 MPa. This second category of dentinal adhesives is the subject of this paper. An attempt is made to draw a parallel between the penetrative ability of the adhesive (the wettability of the dentinal substrate) and the efficacy of the adhesive bond as determined by shear bond strength values. Category III dentinal adhesives will be discussed in another paper.

Adhesives↗

PubMed1991

Indirect determination of isocyanates by gas chromatography.

A gas chromatographic method was developed to determine the purity of synthesized isocyanate monomers, specifically isocyanatoacrylates, and to determine the isocyanate content of synthesized polymers and prepolymers. The method is a modification of an ASTM procedure in which an isocyanate is allowed to react with excess di-n-butylamine. In the ASTM method, the amount of isocyanate present is calculated indirectly from the amount of unreacted di-n-butylamine, determined by back titration with standard hydrochloric acid. Determination of the excess di-n-butylamine by the gas chromatographic method developed has the advantages of providing better precision and requiring less sample than the titrimetric method. The two methods were compared using phenyl isocyanate as a model test compound. A synthesized monomer, methyl alpha-isocyanatoacrylate, was also analyzed, for comparison by both methods.

Chromatography, Gas↗