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Biomedical subjects

A Ben-Amar

Publications and source records attributed to A Ben-Amar.

At least 19 recordsLinked to original sources
PubMed2001

Improving the seal of amalgam cores with cemented dowels: a comparative in vitro radioactive tracer study.

Amalgam cores with cemented dowels are commonly used to restore endodontically treated teeth. These restorations were widely studied for their mechanical properties; however, less is known about their sealing ability. The effect of the cement type used for the dowel and that of a bonding agent application were studied in a radioactive tracer coronal leakage study. The sealing ability of posts and cores was also compared with that of 5 mm remaining root canal fillings. Composite luting cement provided a better seal than zinc phosphate cement. The seal provided by 5 mm root canal fillings was poorer than that provided by posts and cores. High variability in seal quality was found among all types of posts and cores studied. This may indicate that the seal provided by cemented dowels with amalgam cores is unpredictable. Because neither the remaining root canal filling nor the post and core may be trusted alone for a seal, each should be performed with the greatest care and both covered with a crown as soon as possible.

Bicuspid↗
PubMed2001

Effect of repeated vertical loads on microleakage of IRM and calcium sulfate-based temporary fillings.

Temporary fillings are commonly used to seal endodontic access cavities between visits. IRM and Cavidentin were selected to represent two widely used groups of temporary filling materials. The first is a reinforced zinc oxide-eugenol preparation that is mixed at chairside, whereas the second is a ready-to-use calcium sulfate-based material that gained popularity due to its convenience of application. The seal provided by the aforementioned materials was studied using a radioactive tracer quantitative assay. When compared as passive temporary filling, the two provided a similar quality of seal. However, when subjected to repetitive "occlusal" cyclic loading of 4 kg, IRM was clearly superior to the calcium sulfate-based material. Whereas IRM maintained a reasonable seal, the calcium sulfate-based fillings deteriorated and lost the ability to seal. These results suggest that even though calcium sulfate-based materials may be useful when not subjected to any occlusal forces, IRM should be preferred whenever occlusal loads may be applied. Furthermore it is demonstrated that testing such materials for microleakage with no reference to mastication forces may be of limited value.

Bite Force↗
PubMed1999

Comparison of microleakage for three one-bottle and three multiple-step dentin bonding agents.

PURPOSE: This in vitro study compared the ability of several recently introduced 1-bottle adhesives to their preceding multiple-step dentin bonding agents in reducing microleakage around Class V composite restorations. MATERIAL AND METHODS: Facial and lingual Class V cavities were prepared in 48 molar teeth, which were randomly divided into 6 equal groups. Three groups used the fourth-generation multiple-step systems, and 3 used the fifth-generation single-bottle adhesives. All cavities were restored by composite and subjected to thermocycling and intermittent occlusal loading. After immersion in 0.5% basic fuchsin, the teeth were cut faciolingually in 5 consecutive sections and evaluated for dye penetration using a binocular stereomicroscope. RESULTS: There was no statistically significant difference in the degree of microleakage comparing the adhesive's generation and manufacturer and the location of the cavity margins. A significant interaction was found between margin location and manufacturer, which implied that the sealing capacity at the enamel and cementum margins was material-specific. CONCLUSION: Scotchbond Multi-Purpose and Single Bond adhesives provided the best seal for enamel margins, and One-Step and Optibond FL adhesives were best for cementum margins.

Adhesives↗
PubMed1999

pH changes of glass-ionomer lining materials at various time intervals.

The purpose of this in vitro study was to evaluate pH changes of resin modified glass-ionomer (RMGI) and conventional glass-ionomer liners at short-term intervals after mixing to relate the timing of light activation on the acidity of RMGI lining materials. The RMGI liners tested were Vitrebond (3M), Variglass VLC (Dentsply), Fuji Lining LC (GC Dental Industrial Corp.) compared to a traditional glass-ionomer liner: Lining Cement (GC, control). Light activation of liners was carried out at different time intervals after mixing. The pH changes of each liner were evaluated immediately after mixing and thereafter every minute for 8 min using a surface pH meter. All liners tested exhibited a gradual increase in surface pH over time. The delay of light activation of RMGI lining materials after mixing did not significantly decrease the acidity of the liner during the first 9 min post-mixing.

Acids↗
PubMed1997

Marginal seal of composite inlays using different polymerization techniques.

The effect of indirect and semi-direct curing systems of Cl II composite inlays on microleakage was investigated in vitro and compared to conventional direct posterior composite restorations. Nearly identical Cl II cavities were restored with the same composite resin using different polymerization systems. Microleakage assessment was carried out after cyclic loading and thermal stressing by assessing the dye penetration. The data showed that all inlay techniques resulted in improved marginal sealing compared with conventional restorations. However, the indirect procedure resulted in significantly reduced microleakage compared to the semi-direct inlay techniques.

Acid Etching, Dental↗
PubMed1996

Reduction of microleakage in class II composite resin restorations using retentive pins.

The effect on microleakage of Bondent parapulpal pins used in class II composite resin restorations was evaluated in vitro. Bulk and incremental packing and polymerization techniques were compared, using pins anchored at the gingival cavity walls. Evaluation of microleakage was carried out following cyclic load application and an extended thermocycling procedure by the assessment of dye penetration. The results showed that the use of pins at the gingival wall of class II composite resin restorations provided significantly improved marginal sealing. The procedure should, therefore, be regarded as an effective clinical practice.

Composite Resins↗
PubMed1995

Removal of overextended gutta-percha root canal fillings in endodontic failure cases.

A procedure is proposed for the complete removal of an overextended root canal filling when associated with a root canal treatment failure. First, the gutta-percha is softened with xylene and removed to a distance of 2 to 3 mm short of the apex. Second, the remaining gutta-percha, which is preserved as solid as possible, is removed by a Hedstrom file. The file is extended 0.5 to 1.0 mm beyond the apex, firmly engages the gutta-percha and is slowly removed. In 17 of the 18 cases, this procedure successfully removed the overextended gutta-percha.

Extravasation of Diagnostic and Therapeutic Materi↗
PubMed1995

The rate of OH- ion release from lining materials containing calcium hydroxide.

Four light-cured calcium hydroxide and three chemically cured resin-based lining materials were compared for hydoxil ion (OH-) release. Results indicated that the chemically cured calcium hydroxide cements were capable of OH- release for a longer period than the light-cured resin bases. Alkaliner (a chemically cured liner) produced and maintained the highest alkaline environment in the long-term, whereas calcium fluoride liner and Basic-L (both resin-based) showed the lowest values of OH- ion release.

Analysis of Variance↗
PubMed1995

The sealing of the tooth/amalgam interface by corrosion products.

A marginal gap exists between the amalgam restoration and the cavity walls. At this interface, there is a constant percolation of fluid containing ions, molecules and bacteria. With time, corrosion products of the amalgam components seal the gap at the amalgam/tooth interface. The corrosion processes for conventional and high copper amalgam and factors affecting the corrosion deposits are reviewed. Better amalgam adaptation to the cavity walls improves the chances of sealing the restoration by corrosion products. The effectiveness of cavity varnish in preventing microleakage until corrosive deposits are formed is discussed.

Copper↗
PubMed1995

Antibacterial activity of three dental liners.

PURPOSE: The purpose of the present study was to assess the antibacterial activity of the following three dental liners: Vitrebond (3M, St Paul, MN), Dycal (LD Caulk, Dentsply International, Milford, DE), and Life (Kerr, Romulus, MI). MATERIALS AND METHODS: The test was based on a modification of the agar diffusion test in which samples were placed on agar plates previously inoculated with Streptococcus mutans and were removed after predetermined time periods. The material's effect on bacterial growth was evaluated. RESULTS: Results show that Vitrebond has a strong antibacterial effect that was evident after 1 minute of direct contact with the inoculated bacteria. It was significantly more effective (P<.0001) than Dycal or Life. CONCLUSIONS: This method allows for the evaluation of the antibacterial effect of dental materials.

Analysis of Variance↗
PubMed1995

Effect of mouthguard bleaching on enamel surface.

PURPOSE: To evaluate in vitro the effect of 10% carbamide peroxide in a mouthguard on the shear bond strength of resin composite to bleached enamel surfaces and morphological changes in these surfaces. MATERIALS AND METHODS: Thirty anterior extracted were divided into a control and a test group. Plastic trays were made for each tooth and the test group treated with Opalescence bleaching gel and incubated at 37 degrees C humid environment for 8 hours. The bleaching agent was washed and the trays replaced with water-soaked cotton wool for another 16 hours in the incubator. This procedure was repeated every day for 21 days. The control group was just treated with the water-soaked cotton wool. Selected teeth from both groups were evaluated with the SEM and 72 hours after the bleaching treatment, Scotchbond 2/Silux Plus rings were bonded to the enamel surfaces in both groups and sher bond strength testing performed. RESULTS: Bleaching created some enamel porosity and significant reduction in the resin composite shear bond strength.

Carbamide Peroxide↗
PubMed1994

Long term sealing properties of Amalgambond under amalgam restorations.

The degree of microleakage at 14 days, 6 months and 1 year between Class V amalgam restorations lined with Copalite varnish or with Amalgambond was compared in this in vitro study. The restored teeth were subjected to cyclic occlusal loading, thermocycling procedures and then stored in a dye solution at the appropriate intervals. Dye penetration was assessed at the gingival and occlusal margins of the restorations. The results showed that with Amalgambond, there was significantly better sealing of the dentin tubules than with Copalite or unlined restorations (P < 0.001) at all times tested. Amalgambond showed significantly less microleakage as compared to unlined restorations (P < 0.01) at all time periods, and significantly less short-term (14 days) microleakage compared with the Copalite-lined group (P < 0.01).

Dental Amalgam↗
PubMed1993

The effect of porcelain color on the hardness of luting composite resin cement.

Visible light- and dual-curing composite resin luting cements were cured under porcelain disks of different colors to examine the effect of porcelain color on surface hardness. Knoop microhardness measurements were made at exposure times of 48, 72, and 120 seconds. Higher levels of hardness were obtained with dual-cured resin. Visible light-cured resin irradiated through colored porcelain required more prolonged exposure times to reach a degree of hardness approaching that of dual-cure resin. From the standpoint of microhardness, dual-cured composite resin is preferred for luting porcelain restorations of > or = 2 mm thickness.

Analysis of Variance↗
PubMed1993

Varnish application technique and microleakage of amalgam restorations.

Various techniques for applying two types of varnish to control microleakage of Class V amalgam restorations were compared in vitro. The drying time for each layer of varnish with a gentle air spray was varied, including delays in applying the second coat and the placement of the amalgam restoration. Microleakage was recorded by dye penetration. Both varnishes were inefficient at reducing dye penetration at the gingival wall. There were no statistical differences in dye penetration at the gingival wall between the two varnishes, regardless of the method of application, or the presence of varnish. Both varnishes exhibited good sealing properties at the occlusal wall when used according to the manufacturer's instructions, but varnish application was technique-sensitive. Short-cuts in the procedure may increase leakage; too short a drying time of either varnish can cause microleakage similar to the control group without a varnish.

Analysis of Variance↗
PubMed1991

Effect of water spray on lining materials and their adhesion to composite and dentin cavity walls.

The effect of an air-water spray on the adhesion of lining materials to both overlying composite restorations and cavity walls was evaluated. An in vitro study was performed on extracted molar teeth: Two resinous light-cured liners and one calcium hydroxide, chemically activated liner were compared. Teeth were restored with composite materials and subjected to cyclic thermal changes so that microleakage could be evaluated. Results indicated that adaptation between the restorative material and the liner was effective, regardless of whether the oxygen-inhibited layer was removed by being rinsed. A definite gap was detected between the liners tested and the dentin cavity walls.

Acrylic Resins↗
PubMed1991

The fluid-filled gap under amalgam and resin composite restorations.

This article discusses the factors involved in the formation of marginal gaps between amalgam or resin composite restorative materials and cavity walls. The fluid that penetrates the microspace from the oral cavity and from the dentinal tubules is followed by bacterial invasion. This process can lead to secondary caries and irritation of the dentin/pulp complex. The bacterial growth is controlled by effective sealing at the tooth/restoration interface, partial obliteration of the gap, accumulation of solids at the cavosurface margins of the restorations, and by antibacterial linings.

Animals↗
PubMed1990

Long-term use of dentine adhesive as an interfacial sealer under Class II amalgam restorations.

An in vitro study was carried out to evaluate the long-term sealing properties of a light-cured dentine adhesive in Class II amalgam restorations. The restorations were subjected to repeated vertical occlusal loads and a number of thermocycling procedures. The results demonstrated significant advantages of using a dentine adhesive as an interfacial sealer in order to reduce microleakage, compared to a conventional Copal varnish.

Composite Resins↗