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Biomedical subjects

M Staninec

Publications and source records attributed to M Staninec.

At least 19 recordsLinked to original sources
PubMed2002

Dentin shear strength: effect of distance from the pulp.

OBJECTIVE: Dentin structure varies with orientation and location. Ultimate shear strength (USS) has also been found in previous studies to vary with location. The present study further explores this relationship between USS and various locations in coronal dentin as well as distance from the pulp. METHODS: Stick specimens were prepared from coronal dentin located in the center or under cusps of human molar teeth. These were tested in the shear mode at various distances from the pulp. RESULTS: Median values ranged from 52.7 (range 29.0-73.1) MPa near the pulp to 76.7 (range 53.9-104.0) MPa near the dentino-enamel junction. No differences were found among the buccal, central or lingual locations, however, the USS near the pulp was found to be significantly lower. SIGNIFICANCE: The properties of coronal dentin vary with distance from the pulp, which may affect adhesion and other aspects of restorative dentistry.

Anisotropy↗
PubMed1999

The development of resin-bonding for amalgam restorations.

Adhesive techniques are now used for many dental restorative materials, including amalgam. Several generations of dentine bonding agents have been developed, mainly for bonding composite resins. When bonding is used with amalgam restorations, the need for retention and resistance form is reduced, the seal is improved, and some procedures, such as amalgam sealants, which were not previously possible, can be considered.

Acid Etching, Dental↗
PubMed1999

Inhibition of carious lesions in vitro around gallium alloy restorations by fluoride releasing resin-ionomer cement.

A new fluoride releasing resin-ionomer cement was used for bonding of gallium alloy restorations in vitro. Etching, priming, and fluoride releasing resin-ionomer cement were used in the experimental group (ARG), prior to placement of the gallium alloy restorations. Three different controls were used: gallium alloy only (G), no etching, fluoride releasing resin-ionomer cement, gallium alloy (RG), etching, priming, non-fluoride cement and gallium alloy (ACG). The mean shear bond strengths of ARG group to enamel and dentin were higher than those of the three control groups. Artificial secondary caries lesions around the restorations in the experimental group and the control groups were produced, using a strep. mutans culture. The microradiographs were examined for presence of a caries inhibition zone near the restoration. Caries inhibition zones were clearly detected around RG and ARG, but not around G and ACG. The results indicate that the fluoride releasing resin-ionomer cement provided good adhesion and caries inhibition in enamel and dentin.

Adhesiveness↗
PubMed1999

Artificial caries removal and inhibition of artificial secondary caries by pulsed CO2 laser irradiation.

PURPOSE: To investigate the inhibition of artifical secondary caries around restorations placed after removal of artificial caries by pulsed CO2 laser irradiation and by mechanical means. MATERIALS & METHODS: Beveled cavities were prepared mechanically on the facial surfaces of extracted human molars. Each cavity was subsequently exposed to an artificial caries (demineralizing) solution (pH 5.0) for 7 d to generate a demineralized zone approximately 100-200 microns thick on the cavity surface. The artificial carious/demineralized zones of the cavities were removed by a pulsed CO2 laser operating at a wavelength of 9.3 microns with pulse duration of 100 microseconds and an irradiation intensity of 5 J/cm2. Artificial control caries were removed mechanically with a carbide bur in a slow speed handpiece. The cavities were slightly undercut and restored with a resin-based composite without etching and bonding and the restored teeth were subjected to pH cycling solutions for 10 d as follows: Demineralization solution, pH 4.5 for 6 hrs, followed by remineralization solution, pH 7.0 for 18 hrs. Cycled teeth were sectioned through the restorations and the resulting lesions were analyzed in thin section using polarized light and Knoop microhardness. RESULTS: Mean microhardness delta Z values, indicating mineral loss were: 549 (SD 191) for control, and 140 (SD 127) N = 11. This difference is significant with t = 5.543 and P = 0.000 (Paired t-test). Caries penetration: Control side--231 microns (SD 71), Laser treated side: 123 microns (SD 79) N = 6. This difference is significant with t = 5.198 and P = 0.003 (Paired t-test). The results show that the laser treatment not only removed artificial caries, but also inhibited decalcification of the cavity wall in a subsequent artificial caries challenge by as much as 81% compared to control samples. No etching and bonding was used in this pilot study, which might have influenced the results. Future studies should address the inhibition effect of the laser treatment as compared to adhesive techniques, fluoride treatments and fluoride release restorative materials. CONCLUSION: Caries removal by a pulsed lambda = 9.3 microns CO2 laser produces a cavity surface morphology with marked resistance to artificial secondary caries as compared to mechanical removal.

Carbon Dioxide↗
PubMed1999

A two-year randomized, controlled clinical evaluation of bonded amalgam restorations.

PURPOSE: The clinical performance of adhesively bonded dental amalgam restorations was compared with that of traditionally placed non-bonded control amalgams in a randomized prospective study. MATERIALS AND METHODS: One-hundred thirteen Class II Dispersalloy amalgams were placed in permanent molars and premolars of 31 (21 males, 10 females) human subjects with their informed consent. By random assignment, 60 amalgam restorations were adhesively bonded using ED Primer and Panavia 21 TC (both Kuraray Co, Japan), and 53 traditional non-bonded restorations were placed. Most preparations involved replacement of defective amalgam restorations. Clinical recalls were conducted by experienced evaluators using modified USPHS criteria for occlusal and proximal anatomic form, occlusal and proximal marginal adaptation, and occlusal and proximal surface roughness. RESULTS: For the categories of anatomic form, marginal adaptation, surface quality, and temperature sensitivity, there were no significant differences between bonded and non-bonded amalgam restorations (chi-square analysis, p > 0.05). Three non-bonded restorations were lost at 4, 7, and 24 months from preparations with no deliberate retention. CONCLUSION: After two years' clinical service, there were no failures among the amalgam restorations adhesively bonded using ED Primer and Panavia 21 TC, but three non-bonded restorations failed due to lack of retention. For traditional preparations, adhesively bonded amalgams of the type investigated perform as well as non-bonded amalgams over two years' clinical service.

Bicuspid↗
PubMed1998

Bonded amalgam sealants: two-year clinical results.

The authors used bonded amalgams as pit and fissure sealants without mechanical preparation. They compared the two-year retention of the bonded amalgams with that of resin-based pit and fissure sealants. Clinical examinations at six months, one year and two years revealed no difference between the retention of the two sealants. This technique opens up the possibility of using bonded amalgam in pits and fissures surrounding very conservative preparations in a preventive amalgam restoration.

Acid Etching, Dental↗
PubMed1997

Effect of resin-modified glass ionomer cements on secondary caries.

PURPOSE: To evaluate the in vitro secondary caries inhibitory effect of two resin-modified glass ionomer cements (R-GICs). MATERIALS AND METHODS: Class V cavities were prepared at the cementoenamel junction on facial and lingual surfaces of 32 extracted upper premolars. The facial cavities were restored with a conventional glass ionomer cement (GIC) (Fuji II), while the lingual cavities were restored with either one of the R-GICs (Fuji II LC, Photac Fil, Vitremer), or a resin composite (Z-100). The margins of the restorations were subjected to a 20-day in vitro cariogenic challenge and the degree of demineralization was analyzed by microradiography. The amounts of fluoride released into distilled water from disc specimens of the materials tested were also measured for immersion time up to 161 days. RESULTS: The R-GICs and GIC's released similar cumulative amounts of fluoride over 161 days. Photac-Fil showed significantly higher amounts of fluoride release over the same period. The depth of the outer lesion and the thickness of the acid-resistant layer showed no significant difference among the R-GICs and GIC's. Moreover, the residual fluoride and calcium in the dentin adjacent to the R-GICs and GIC's were correlated with the thickness of acid-resistant layers in the dentin adjacent to the R-GICs and GIC's by electron probe microanalysis. However, the inhibitory effect of the R-GICs was not directly related to the fluoride concentrations eluted from them.

Bicuspid↗
PubMed1997

Bond strengths of the adhesive resin-amalgam interface.

PURPOSE: To evaluate the tensile and shear bond strengths of eight adhesives and two amalgams (spherical and lathe cut). MATERIALS AND METHODS: Two high-copper amalgams (Tytin, spherical; and ANA-2000, dispersed phase) and seven adhesives (Panavia EX, C&B Metabond, Chameleon Metal Resin Cement, All-Bond 2, All-Bond C&B, Photo-Bond and Imperva Dual) were evaluated. An epoxy resin (Stycast 1266) was included as a control for comparison because it was an adhesive material of similar viscosity but different chemistry from the dental adhesives. The aluminum surfaces were sandblasted with 50 microns aluminum oxide just prior to coating with adhesive resins. The testing area was defined with a 4 mm circular adhesive Mylar mask. All adhesives were mixed and handled according to manufacturers' instructions. Freshly mixed amalgam was condensed into the test cavity and onto the surface immediately after coating with adhesive. After 24 hours storage, the bond strengths were determined in an Instron testing machine at a crosshead speed of 2 mm/minute. The debonded surfaces were examined in an optical microscope for site of failure. The few samples which showed failure at the aluminum-resin interface were not included in the study. Selected debonded surfaces were examined by SEM. A 2-way ANOVA (General Levin Models-GLM) was used to analyze the data from both the tensile and shear bond strength tests. GLM was used instead of standard ANOVA because of the unbalanced design. The lack of balance occurred because some of the bonding resin/amalgam groups had different sample numbers. RESULTS: A wide variation in bond strengths was obtained with adhesive resin cements and not all appeared suitable for adhesive amalgam restorations. Panavia EX, C&B Metabond, Chameleon Metal Resin Cement and All-Bond C&B showed the best potential for amalgam bonding, with shear and tensile bond strengths greater than 8 MPa. Viscous, filled versions of adhesives appeared to be more effective. Choice of amalgam appeared to be less important than choice of adhesive.

Analysis of Variance↗
PubMed1995

Bond strength, interfacial characterization, and fracture surface analysis for a new stress-breaking bonding agent.

Three commercial dentin bonding systems were analyzed by tensile bond testing, area analysis of fractured surfaces, and SEM analysis of the tooth-resin interfaces. Tensile bond strengths in megapascals(SD) were Tenure-Marathon V ([T-M]; 8.86[3.02]), new system with low-viscosity resin ([K-LVR-P]; 6.50[2.01]), and new system without low-viscosity resin ([K-P] = 7.28[1.75]), which were significantly greater than Scotch-bond 2-P50 ([SB-P50]; 3.96[1.02]). Gaps that ranged up to 5.6 microns (mean for the group) were observed around most of the restorations at dentin surfaces and less so at enamel surfaces, where some of the restorations remained free of gaps. The gaps near the dentin margin were significantly smaller for K-LVR-P than for SB-P50. The tensile test revealed mixed failure modes in all systems, and in the cross sections of class V restorations, the gaps were confined to the dentin-resin junction.

Analysis of Variance↗
PubMed1994

Mechanical retention versus bonding of amalgam and gallium alloy restorations.

The retention of amalgam and gallium alloy restorations in proximal box forms was measured in vitro, and three different adhesives to conventional undercuts were compared. For control, restorations were placed without undercuts or adhesives. No significant difference was found between amalgam and gallium alloys with each of the five methods of retention used. Alloys placed without retention or adhesives were significantly less retentive than all other groups. When Tytin alloy was used, no difference was found in retention among the restorations retained with Panavia or All-Bond adhesive or an occlusal dovetail and retention grooves, but Amalgambond adhesive was less retentive than all three of these methods. When gallium alloy was used, both Panavia and All-Bond adhesive were more retentive than undercuts, but the effect of Amalgambond adhesive was more retentive than undercuts, but the effect of Amalgambond adhesive was comparable to that of undercuts. The results of this study indicate that adhesives could be used in place of traditional undercuts to retain amalgam and gallium alloys, thus saving a considerable amount of tooth structure.

Acid Etching, Dental↗
PubMed1994

Shear bond strength of amalgam adhesives to dentin.

This study compared the bond strength of resinous adhesives used to bond amalgam to dentin. The adhesives were: All-Bond 2 (AB), Liner-F (LF), SuperBond C&B (SB), Amalgambond (AM), Photo Bond (PB), and Panavia (PA). Occlusal surfaces of non-carious molars were ground wet to 600 grit finish, exposing dentin. The dentin surfaces were conditioned and the adhesives were applied according to manufacturers' instructions. Dispersalloy amalgam (D) was condensed onto the adhesive immediately. For comparison, resin composite, Photo Posterior (PO) and Bis-Fil (BIS) were used. After 24 hours of storage in 100% humidity at room temperature, shear bond strengths were determined with a shear testing jig in an Instron testing machine at a crosshead speed of 0.5 mm/minute. The data were compared using ANOVA, P < 0.01. AB, LF, D had significantly higher bond strengths than other amalgam adhesives. There was no significant difference between SB, D and PB, PO. Bond strength of PB, PA, D was significantly higher than PA, D. Thus, there were significant differences among adhesives for bonding amalgams. Amalgam to dentin and composite to dentin bond strength were comparable except for the All-Bond groups. Fracture patterns at the dentin/restoration interfaces were examined by scanning electron microscopy (SEM).

Analysis of Variance↗
PubMed1993

Adhesion and microleakage tests of a new dentin bonding system.

Adhesion to dentin and microleakage of a new dentin bonding system was studied. The new system includes a low viscosity lightly filled Bis-GMA based resin liner which is placed between the phosphate ester-containing adhesive layer and the composite. This system was compared to dentin bonding agents based on: 1) HEMA and Bis-GMA and 2) PMDM and NTG-GMA. The phosphate ester system was used with and without the low viscosity resin. Each system was used with its corresponding posterior composite. All groups were tested by shear and tensile bond testing immediately and up to 6 mon after bonding. Microleakage of the three systems was tested in Class V restorations by dye penetration. The results of the shear and tensile tests indicated that significant changes within groups occurred with time, and significant differences appeared between groups at various times. The use of low viscosity resin with the phosphate ester system resulted in decreased leakage. The amount of leakage observed was related to early shear bond strength. This study suggests that the properties of the layer immediately adjacent to the adhesive may affect the performance of the system.

Adhesiveness↗
PubMed1992

Effect of bonded amalgam on the fracture resistance of teeth.

The purpose of this study was to determine whether amalgam bonded to tooth structure with an adhesive resin cement can increase the fracture resistance of restored teeth. Extracted paired upper premolars were prepared for G.V. Black type mesioocclusodistal amalgam restorations. In one tooth of each pair (the experimental group), the enamel walls were etched with phosphoric acid and were painted with an adhesive resin (Panavia), and amalgam was condensed and carved. For the other tooth in each pair (the control group), amalgam was placed in the same manner but was not etched and lined with resin. The teeth were thermocycled and mounted for testing and then were loaded until fracture. A significant difference (p less than 0.05, the paired Student's t-test) was found in the force needed to fracture the bonded amalgam group (70.5 +/- 21.6 kg) compared with that needed to fracture the conventional amalgam group (60.3 +/- 16.8 kg). SEM examination of fractures at the interface occurred predominantly within the resin.

Acid Etching, Dental↗
PubMed1992

Tensile adhesion evaluation in a new universal test.

A tensile testing jig was designed to test adhesion between various materials and tooth surfaces, and between materials of various consistencies, modes of setting and properties. This study examined the adhesion of both flowable and condensable, light cured and chemically cured, direct and indirect restorative materials to dentin. All materials were mixed and placed according to manufacturer's directions. The bonds were tested in tension after 24 hours. The substrate was dentin, except in group 1. Results in MPa +/- SD: 1. Photobond & Photoposterior to enamel 15.84 +/- 3.93; 2. Superbond C&B and metal inlay 6.20 +/- 3.00; 3. SuperBond C&B and amalgam 5.76 +/- 1.89; 4. All-Bond and metal inlay 4.46 +/- 1.16; 5. Mirage Bond and Newbond and amalgam 2.97 +/- 0.85; 6. Vitrebond 2.06 +/- 0.95; 7. Newbond and amalgam 1.70 +/- 0.61; 8. Ketac-Bond 0.73 +/- 0.40. The groups (2,3,4), (4,5), (5,6,7) and (6,7,8) were not significantly different at the 95% confidence level, calculated by the Student-Newman-Keuls test. The testing method was useful for all materials studied.

Adhesives↗
PubMed1992

Effect of bonded gold inlays on fracture resistance of teeth.

The purpose of this study was to determine if bonding gold inlays to tooth structure with an adhesive resin cement would increase the fracture resistance of restored teeth. Extracted paired maxillary premolars were prepared for mesio-occlusodistal inlays, and the inlays were cast in type II gold. In one tooth of each pair, the inlay was sandblasted with aluminium oxide, tin plated, and cemented with an adhesive resin into the etched preparation. For the other (control) tooth in each pair, the inlay was sandblasted and then cemented into the preparation with zinc phosphate cement. The teeth were thermocycled and loaded until fracture. The teeth in the bonded group had a statistically significantly higher fracture resistance than did the teeth in the control group. Scanning electron microscopic examination revealed that failure in the bonded group occurred predominantly within the resin.

Bicuspid↗
PubMed1989

Comparative evaluation of the sensitometric properties of screen-film systems and conventional dental receptors for intraoral radiography.

This investigation determined the sensitometric properties of 27 rare-earth screen-film combinations and compared them to E- and D-speed films and xeroradiography, the current standards for intraoral radiography. A series of exposures from base plus fog to film saturation were made to determine the Hurter and Driffield curve of each image receptor. The base plus fog, film saturation, speed, gamma, average gradient, and resolution were determined. When dental receptors and screen-film systems are compared on the basis of radiographic quality (contrast and resolution), many screen-film systems have similar resolution (greater than 10 line pairs/mm), significantly greater contrast (greater than 2.0), and a substantial speed advantage (greater than 10). Thus selected screen-film systems may be an alternative to conventional dental receptors for intraoral radiography.

Evaluation Studies as Topic↗
PubMed1989

Effect of developer temperature changes on the sensitometric properties of direct exposure and screen-film imaging systems.

A heat exchanger was developed and incorporated into the recirculation system of a dental processor to maintain strict temperature control. Without the heat exchanger, developer temperature rose steadily over 8 h to a maximum of 35.7 degrees C: with the heat exchanger it was maintained, regardless of ambient conditions, at the desired temperature with virtually no fluctuation. Sensitometric properties of base and fog, speed, and average gradient were measured for D and E speed films and Lanex Regular/T-Mat G and Lanex Fast/T-Mat Hscreen-film systems at developer temperatures of 21.1, 23.8, 26.7, 29.4 and 32.2 degrees C. Small changes in these properties were found for D and E speed films: on the other hand, Lanex Regular/T-Mat G showed a 65% increase in base and fog and Lanex Fast/T-Mat H a 43% increase in average gradient over the temperature range studied. Although these changes may not be clinically significant for intra-oral and dental radiography, the variations in image quality may compromise controlled imaging experiments and clinically compromise radiographic quality when using screen-film systems.

Radiography, Dental↗