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Margin quality and isotope microleakage analyses of Class II restorations placed in extracted human molars were compared using various composite resins and placement techniques. At occlusal margins, the traditional (experimental) composite resin restoration placed by the incremental technique showed less microleakage than did the traditional (commercial) [corrected] composite resin restoration placed by the bulk technique. In each group, the occlusal and proximal adaptations had significantly higher "excellent margin" than did the cervical adaptation. Thus, the marginal adaptation at the cervical aspect of conventional Class II composite resin restorations may present a problem with respect to microleakage.

A method is described to quantify marginal leakage of amalgam restorations in vitro as a function of time. The method consists of the determination of the amount of nitrogen gas passing through the margins of the restoration at 2 atm. pressure in 30 min. The method described needs about sixteen specimen per experiment. The standard error is 20-30% of the mean leakage value and is independent of the type of condensation and the amalgam type. Two amalgams, the non-gamma 2-Dispersalloy and the conventional, Amalcap was compared longitudinally over a period of 4 months. The results showed: (1) The marginal leakage of Dispersalloy decreased strongly with time; the time dependency of Amalcap was less pronounced. (2) That carefully condensed Amalcap showed significantly less marginal leakage than Dispersalloy. (3) Whereas the marginal leakage of Amalcap was dependent on the condensation procedure, the leakage of Dispersalloy did not depend strongly on it.

The marginal leakage of five adhesive composites placed in class V cavities extending into the root was examined by immersing the specimens in China ink after thermal cycling. Clearfil F II-initial bond, Silar-Scotch Bond, and Miradapt-D21 materials did not show leakage when all cavity walls were totally etched, whereas they showed leakage at the dentinal/cemental wall when only enamel was etched. In either conditions Clearfil F II-New Bond materials did not show leakage and Miradapt material showed leakage. Manipulative variables affected the seal of Clearfil F II-New Bond materials. Insertion later than 3 minutes after applying New Bond material induced microleakage. The use of pressure under a matrix did not affect the seal. Maintaining dryness for 3 minutes at the etched dentinal/cemental margin and 1 minute at the etched enamel margin was sufficient to prevent microleakage. Finishing before the initial polymerization of the composite or lining the whole axial wall caused microleakage.

Composite resin restorative materials have been used in dental practice for over 25 years. The original composite resins were subjected to discolouration and marginal breakdown. These problems have largely been overcome with the exception of marginal gaps at the dentine-restoration interface. The introduction of dentine adhesives has reduced but not eliminate this problem. This study shows how the marginal gaps at the dentine-restoration interface were significantly reduced firstly by the introduction of an intermediate resin and then further by using a dentine adhesive.

One hundred and twenty caries-free molar teeth were stored in saline. Three types of cavities were prepared in these teeth: conventional MOD, parallel-sided MOD with no buccal or lingual extensions, and a slit cavity. Cavity dimensions were recorded. Each group of teeth were restored with either a microfine or conventional composite, used in conjunction with a dentine adhesive. Cusp movement was recorded via two linear variable displacement transducers attached to the cusps. Using dye penetration studies, the marginal adaptation of the material to the teeth was assessed. In a small number of cases, the amount and type of cuspal movement and the degree of dye penetration was variable, depending on cavity design and the composite used, but generally cusp movement was unaffected by variation in cavity outline.

The purpose of this study was to quantitatively evaluate the sealing properties of various temporary restorative materials used in standard endodontic access preparations by using a newly introduced fluid filtration method. The materials tested were Cavit, Cavit-G, TERM, glass ionomer cement, zinc phosphate cement, polycarboxylate cement, and IRM. Extracted human incisor, canine, and premolar teeth were used, and each tooth served as its own control by testing for microleakage prior to access preparation. Following access preparation, cotton pellets were placed in the pulp chamber so that the space remaining for the restoration was 4 mm. Immediately after placement of the restoration, the teeth were immersed in Ringer's solution and incubated at 37 degrees C. Microleakage was measured after various time intervals. The results indicated that Cavit, Cavit-G, TERM, and glass ionomer cement provided leakproof seals during the 8-wk testing period, while leakage was observed in 4 of the 10 teeth restored with zinc phosphate cement. IRM and polycarboxylate cement were the least effective of the materials tested for preventing microleakage.

Amalgam can be bonded to etched enamel by a thin coat of Panavia resin cement with a resulting mean bond strength of 1404 psi to enamel and 469 psi to dentin as tested in tension. Less microleakage was observed in resin-bonded amalgam restorations than in Copal varnish-lined or unlined restorations. The technique could be used clinically with possible implications for cavity design, fracture resistance of restored teeth, and recurrent caries. These properties as well as the variables affecting bond strength need further exploration.

The time-dependent microleakage behaviour of two types of restorative materials, a microfilled composite resin and a glass ionomer, was studied. A dentine bonding agent was also included. This study was based on a diffusion model of microleakage. It was found that the initial gap sizes of the restorations increased progressively for restorations microfilled with bonding agent, microfilled alone, and glass ionomers, in that order. Analysis of microleakage over some periods suggests that the gap size of the restorations by microfilled with bonding agent may increase with time, and that while restorations by glass ionomer and microfilled composite resin decrease in gap sizes with time, glass ionomer restorations show a faster rate of decrease.

The marginal adaptation to acid-etched enamel of a hybrid and a microfilled composite resin, placed with or without intermediate low-viscous resin, was investigated in vivo. Each of 37 patients received four class III test fillings, one with each filling technique. The evaluation was done with the use of SEM on replicas from the cavity margins, 1 week and 1 year after insertion of the fillings. The observed defects were marginal cracks or fractures, chip fractures, and enamel fractures. In the comparison of the size and volume of the marginal defects no significant differences were seen after 1 week between fillings of the same material placed with or without an intermediate resin. However, after 1 year the hybrid resin fillings with an intermediate resin showed significantly better adaptation than the ones without. No difference was found between the microfilled resin fillings. The hybrid resin fillings showed significantly better marginal adaptation than the microfilled resin fillings after 1 week. A further increase of the differences was observed after 1 year.

This investigation revealed no significant difference among the four thermocycling techniques. The use of a dye or an isotope was equally effective and penetrated the tooth/restoration interface to a similar degree. The extent of tracer penetration appeared to be independent of the dwell time in the thermal baths. All procedures involving thermal changes were more potent in demonstrating leakage than the noncycled method.

Single-rooted teeth were instrumented and filled in vitro with a lateral condensation of gutta-percha with sealer. Following obturation, the tooth apices were treated by various retrograde procedures. The teeth were then coated with ethyl acetate, immersed in 45Ca solution, washed, and sectioned, and autoradiographs were used to compare the leakage of the various techniques. Statistical analysis indicated that lateral condensation produced a significantly better seal than any retrograde technique tested except retrofilling with Super EBA cement and that a significantly worse seal was obtained with amalgam retrofill when compared to all retrograde techniques except cold-burnished gutta-percha following apicoectomy. No significant difference existed between other group combinations.

By means of dye penetration, the authors determined the microleakage at the interface of class II composite restorations in thirty-eight extracted or naturally exfoliated primary molars. Scotchbond was used as the bonding agent in half of the prepared cavities' dentin and enamel; the control group (B) used Concise bonding agent in the enamel only. The use of Scotchbond in class II cavities did not prevent marginal leakage under the conditions of this study.