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At least 37 records · Page 2Linked to original sources
PubMed1979

Microleakage around preventive composite fillings in loaded teeth.

The purpose of this study was to evaluate the microleakage around preventive composite fillings in teeth subjected to mechanical loading and thermal cycling, and to assess the influence of the consistency of the composite resin upon the leakage. The fissure enamel was partially removed without dentin exposure in 30 extracted maxillary pre-molars. The cavities were etched with phosphoric acid and filled with undiluted composite (Adaptic) or composite diluted with varying amounts of liquid resin (Adaptic Bonding Agent). Five teeth were not acid etched and served as a control group. All teeth were mechanically loaded and unloaded, simulating masticatory forces, and subsequently thermally cycled between two dye solutions. Extensive leakage was seen around all fillings in the control group, while slight leakage, restricted to the feather-edge margin, was seen in five teeth with acid etched cavities. Three of these contained undiluted composite fillings. Twenty teeth showed no leakage. The results show that preventive composite filling provides good sealing of occlusal fissures, and that the seal is resistant to those thermal and mechanical stresses which may be expected in vivo. The use of diluted composite resin in preventive composite fillings is recommended.

Acid Etching, Dental↗
PubMedDate not supplied

The influence of matrix use on microleakage in Class 5 glass-ionomer restorations.

This in vitro study examined the relationship of matrix use to microleakage in class 5 Ketal-Fil glass-ionomer restorations. Class 5 glass-ionomer restorations were placed on the facial and lingual surfaces of 40 extracted human molars. The occlusal margin was located on enamel, and the cervical margin was located on cementum or dentin. Each tooth had one restoration placed with and without the aid of a soft metal matrix. Specimens were thermocycled (1234 cycles, 6 degrees C -60 degrees C, 30-second dwell time) and immersed in 5% methylene blue dye for four hours. The teeth were sectioned occlusogingivally through the center of each restoration, viewed with an optical microscope (X10), and each restoration was scored for dye penetration around the cavity walls. The enamel and cementum margins were scored separately for the extent of marginal leakage. No difference in leakage was found between restorations placed with or without a matrix (P > 0.05). Enamel restorations leaked significantly less than nonenamel margins, regardless of matrix use (P > 0.05).

Dental Cementum↗
PubMed1992

Microleakage of a composite inlay system.

This study investigated the marginal seal of resin composite inlays in dentin and enamel when either unfilled resin or a second or third generation dentin bonding agent is used. Standardized mesial and distal inlay cavities were cut in 135 human third molar teeth. The teeth were randomly divided into 9 groups and inlays fabricated in a hybrid resin composite inlay material. Each group of teeth was then treated with one of 8 dentin bonding agents or an unfilled resin and cemented with a dual curing resin cement. Each group was stored in deionized water for 1 week, thermocycled between 5 degrees C, 37 degrees C and 55 degrees C for 500 cycles, then placed in 2% methylene blue solution for 15 hours. Following this the teeth were sectioned and scored for the degree of leakage observed. Marginal microleakage was minimal at enamel margins, however there was marked leakage, even when a dentin bonding agent was used, on the dentin side. Only two dentin bonding agents proved more effective than unfilled resin and in only one case was the leakage not significantly worse than in enamel.

Analysis of Variance↗
PubMed1992

Microleakage in the sandwich technique.

This study assessed the microleakage and if it was possible to reproduce the success that is seen in the oral cavity with properly placed "sandwich" restorations. Simulated Class V erosion lesions were prepared in extracted human molar teeth and restored using a Type III glass ionomer lining cement mixed mechanically at a high powder:liquid ratio of 3:1 or greater with resin composite laminated to it leaving cement exposed at the gingival margin. To update the technique for modern materials a dual cure glass ionomer lining cement was placed in a second series with resin composite laminated to it completely covering the gingival margin. The restorations were stored in water for two weeks before temperature cycled and immersed in dye. The results showed minimal leakage relative to most other published studies and that most leakage was related to the setting shrinkage of the resin composite.

Composite Resins↗
PubMed1992

Effect of matrix systems and polymerization techniques on microleakage of Class II resin composite restorations.

This study investigated the effect of different sized light curing tips (2 mm and 11 mm) with curing techniques associated with different matrix systems (Mylar with reflective wedge and metal with wooden wedge) on microleakage of a posterior resin composite material (P-50) placed using a bonding agent (Scotchbond 2). Eighty Class II mesial and distal slot preparations (40 with enamel gingival margins and 40 with dentin gingival margins) were randomly divided into four equal groups: 1) metal matrix, large tip; 2) Mylar matrix, light emitting wedge, large tip; 3) Mylar matrix, light emitting wedge, small tip; 4) metal matrix, small tip. Three-way ANOVA indicated no statistical differences among groups using small and large curing tips. The results showed significantly more leakage (alpha = 0.05) in the dentin gingival cavosurface margin groups than the enamel cavosurface margin groups. The results also showed significantly greater leakage in the polymerization procedures associated with the metal matrix groups (alpha = 0.05) compared to polymerization procedures associated with the Mylar matrix groups.

Analysis of Variance↗
PubMed1978

Marginal microleakage in cemented complete crowns.

An in vivo study was developed to observe the penetration of 131INa around the margins of complete crown castings cemented with zinc phosphate cement with and without the application of different protective agents, with the following results. 1. Complete crowns cemented with zinc phosphate cement showed 131INa marginal leakage differences depending on the protective material used prior to cementation. 2. The best protective agent against marginal leakage according to this study was two layers of cavity varnish applied to the margins. 3. The amount of marginal leakage can be influenced by crown adaptation and the film thickness of the cement. 4. There were no differences between test periods of 1 hour or 21 days after cementation.

Anti-Infective Agents↗
PubMed1978

Microleakage of several amalgam systems: an animal study.

Restorations placed without the application of cavity varnish to the cavity walls and the cavosurface angle exhibited significant marginal leakage after 24 hours and 3 months. At the end of 6 months a decrease in leakage was exhibited with all alloys. With the exception of two specimens, restorations placed after coating the cavity walls and the cavo-surface angle with cavity varnish demonstrated slight or no marginal leakage at all time intervals. The results of this study indicate that the marginal leakage of a conventional filing alloy, a conventional spherical alloy, and two high-copper alloys are approximately the same. The corrosion-resistant high-copper alloys showed the same degree of marginal leakage as the conventional alloys. The results of this study agree with those of a previously reported in vitro study on amalgam leakage.

Animals↗
PubMed1979

Reinforced matrices for pin-amalgam restorations reduce microleakage.

The considerable decrease in microkeakage in the compound-reinforced restorations may be due to the tighter fit of the matrix band at the gingival wall of the preparation, which allows better condensation and marginal sealing of the restoration. The compound prevents lateral migration of the band during condensation pressures.

Dental Amalgam↗
PubMed1979

Effect of composite resin bond agent on microleakage and bond strength.

A study was conducted to evaluate the efficacy of the bonding agents supplied with three composite resins in improving the sealing ability of the materials to tooth structure and the bond of the resins to enamel. When the enamel was not etched prior to insertion of the resin, the use of the bonding agents did not improve marginal seal. Little or no marginal leakage was detected when the restorations were placed by means of the acid etch technique, either with or without use of the respective bonding agents. A slight improvement in the bond of the resins to unetched enamel was secured by use of the bonding agents; however, this advantage was lost when the specimens were thermal cycled. Acid etching of the enamel significantly improved the bond of the strength of all three resins, both when the specimens were thermal-cycled and when stored at a constant temperature. Only one of the commercial bond agents enhanced the bond of its respective composite resin to etched enamel subjected to cycling.

Acid Etching, Dental↗
PubMed1976

The investigation of microleakage in root canal therapy. An electrochemical technique.

An electrochemical technique employing zero-resistance ammetry is described for evaluating the quantity, rate, and areas permeated in the canal system of a root-filled tooth by 1 per cent potassium chloride. Single-rooted extracted teeth were root-filled by a vertical condensation gutta-percha technique. The teeth were coated from the cementoenamel junction to 3 mm. from the apex with a stopping-off medium, so that the apical foramen and the accessory canals in the area would play a role, but not the lateral canals in the gingival area. The teeth were placed in a potassium chloride solution. When the potassium chloride permeated the apical seal and reached a mild steel rod placed through the occlusal access opening extending 2 mm. into the coronal end aspect of the canal, corrosion of the steel was established and was measured for quantity and rate. This technique suggests the possibility of another pathway for tissue fluid to effect coronal dentinal discoloration. The technique also suggests a quantitative means of measuring apical sealing procedures.

Corrosion↗
PubMed1978

Microleakage and marginal adaptation of composite resin restorations.

It has been shown that the use of a sealant offers no advantage with respect to the retentive strength of a composite resin restoration. However, for the improvement of marginal seal and adaptation, the present findings indicate that enamel etching and the application of a sealant, in conjunction with use of a cavity geometry which reduces shrinkage strain, are absolute necessities.

Acid Etching, Dental↗
PubMed1978

Microleakage and enamel finish.

Cavity preparations that are finished with hand instruments allow significantly less marginal leakage than those which are completed only with rotary instruments. This does not mean that hand-instruments walls are perfectly smooth; it only means that these walls allow less marginal leakage. Cavity preparations restored with composite resin showed more marginal leakage than those restored with amalgam. Also, the degree of marginal leakage was greater in cavity preparations restored with composite resin than in those restored with amalgam. Cavity preparations are more prone to marginal leakage at sharply defined cavosurface acute angles than at the smooth or straight surfaces of the cavity. This pattern of marginal leakage was true for both amalgam restorations and composite restorations, but the degree of marginal leakage was greater when composite resin was used as a restorative material. Since less marginal leakage was found in the finished cavity preparations, it is obvious that all cavity preparations must be finished with hand instruments. This may not completely eliminate the problem of marginal leakage, but it will reduce the potential secondary caries both in degree and frequency. Also, since sharply defined acute angles did exhibit more marginal leakage, this part of the cavity preparation needs special attention. With amalgam and composite restorations at least, these angles should not be sharply defined but should be slightly round, so that better condensation of restorative materials can be obtained. This may reduce the degree of marginal leakage.

Composite Resins↗
PubMedDate not supplied

Assessment of microleakage using a conductimetric technique.

A new method enables the dimensional changes of a range of anterior restorative materials to be demonstrated in an artificial cavity. The cavity wall-restoration interspace was incorporated into an electrochemical cell and the changes in the current passing through this cell reflected changes in the dimensions of the interspace.

Acrylic Resins↗