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Biomedical subjects

J F Roulet

Publications and source records attributed to J F Roulet.

At least 19 recordsLinked to original sources
PubMed1992

Marginal adaptation of four tooth-coloured inlay systems in vivo.

This study investigates the margin quality of four different tooth-coloured inlay systems using computer-aided quantitative margin analysis under scanning electron microscopy. Three types of restorations involved chairside procedures using a commercial CAD-CAM apparatus: one type of inlay restoration was milled from preformed glass ceramic blocks, the other two inlay types were milled from preformed porcelain blocks. The fourth system was based on an experimental indirect composite inlay system. Each inlay type was luted with its respective dual-curing luting composite, which was supplied with the system. After 6 months of clinical service, all four systems revealed a significant percentage of submargination indicating occlusal wear of the luting composite. The porcelain inlays and the composite inlays luted with their respective experimental luting composite showed the best marginal adaptation. Luted glass ceramic inlays, in particular, suffered from a significantly higher percentage of inlay margin fractures (9 per cent) and marginal openings (4 per cent) than the other systems. A possible explanation is that the glass ceramic subsurface structure at the inlay-lute interface was weakened by etching with ammonium bifluoride.

Acid Etching, Dental↗
PubMed1992

[Mercury concentration in blood and urine--before and after the placement of dental amalgam fillings].

70 patients of dentist's surgery were given MOD amalgam fillings (non-gamma-2 amalgam) for molars. They were allocated for comparison to four groups defined by their treatment, i.e. the number of old and new restorations and whether a rubber dam was used. Blood and urine samples were collected at regular intervals before and during a 14-day period after treatment and tested for mercury concentration (Hg). Over the observation period the groups with the highest exposure (1-2 old restorations replaced by new ones) showed a tendency, in contrast to the less exposed groups (1 new filling with or without dam), towards increases (p less than 0.10) in group average Hg values of approx. 0.2 microgram/L (blood) and 0.3 microgram/g creatinine (urine) as acute treatment effects. The highest values recorded before and after the treatment, 3.3 micrograms/L (blood) and 16.5 micrograms/L (urine) are higher than normal but do not indicate any increase in the risk to health especially if they are not persistent.

Creatinine↗
PubMed1991

Margin analysis of posterior composites in vivo.

One of the major shortcomings of posterior composites is their tendency to shrink during polymerization. Thirty-three class II cavities were filled with Occlusin (OCC) (12), Coltène EX-D2 (CEX) (10), and Dispersalloy (AM) (11). The composites were placed in beveled, enamel-etched cavities by means of an incremental technique. One week and seven mo after placement, replicas were obtained and quantitatively analyzed in the SEM. The composites showed higher percentages of "excellent margin" (EM) (OCC, 70.6%; CEX-D2, 66.6%) than AM (49.2%) at baseline (p less than 0.01) and after seven mo (p less than 0.01). During the experimental period, the percentage of EM decreased by 10% for AM and OCC and by 14% for CEX-D2 (p less than 0.01). With the composites, an increase of "submargination" (SM) was found: OCC, 8.8%, and CEX-D2, 12.7%. An increase (11.2%) in margin fractures occurred for amalgam. Only OCC showed a low but significant increase (6%) in "marginal openings" (MO). This study confirms the inferior micromorphology of AM at the margins. The high amount of MO with the resin composites (16% after seven mo) indicates that, despite the complicated application technique, leakage of the restorations will occur. The margin analysis showed SM (OCC, 18%; CEX-D2, 21%) after seven mo, indicating severe wear. Class II amalgam restorations should not be replaced with the composites used in this study.

Adolescent↗
PubMed1991

Margin quality of Class III and IV composites in vitro.

Polymerization shrinkage and thermal expansion/contraction of composites counteract marginal bonding. The purpose of this study was to determine the margin quality of Class III and IV microfilled and hybrid composite restorations placed with adhesive techniques. Two experiments were conducted. In experiment 1, small, beveled Class III cavities were prepared in 24 incisors. Twelve cavities were filled with an experimental microfilled composite (COMPAFILL) and 12 with a control microfilled material (DURAFILL). In experiment 2, standardized large, beveled Class IV cavities were prepared in 24 incisors. Twelve of these incisors were filled with DURAFILL and 12 with the hybrid composite HERCULITE XR. The teeth were stored in water for 21 days. Before and after the restorations were thermocycled (5 degrees C-55 degrees C), replicas were obtained for quantitative analysis in the SEM. Statistical analysis (non-parametric tests, p less than 0.05) revealed that the two microfilled materials behaved very well (greater than 95% excellent margins) in Class III restorations before being thermocycled. After the restorations were thermocycled, the margin quality of DURAFILL decreased to 90% excellence, due to the increase in restoration fractures. Thermocycling did not affect the margin quality in the Class IV cavities, and the hybrid composite showed superior margin qualities (89% excellent). Better margin qualities were obtained in Class III cavities. Class IV restorations showed more overhangs (12%) and submargination (6%) which were technique-related. In no cases were greater than 1% marginal openings found.

Acid Etching, Dental↗
PubMed1991

Radiopacity of composites compared with human enamel and dentine.

A 99.5 per cent pure aluminium step-wedge served as reference for evaluating the radiopacity of 55 anterior and posterior composites. The radiopacity of all materials evaluated was compared with the radiopacity of human enamel and human dentine of equivalent sample thickness. Seventeen composites exhibited a radiopacity significantly greater than that of enamel. Some composites intended for posterior use lack the radiopacity required for posterior composite restorations.

Analysis of Variance↗
PubMed1991

Tooth-colored inlays.

There is an increasing need for conservative treatment with tooth-colored inlay restorations due to esthetic concerns and the decreasing acceptance of amalgam. The use of ceramic materials has become possible by using adhesive luting techniques, in which enamel and ceramic inlays are etched and luted with composite resins. The weakest point is still the poor tensile strength of brittle inlay materials, so most efforts are concentrated on strengthening porcelains by ion exchange, tempering, or improving the composition. Despite the fact that adhesively luted inlays show good marginal adaptation, the luting composite layer is worn out because of the low filler fraction of the resins. For composite inlays, the same resins are used as for direct placement. Despite more effective curing techniques, the wear behavior of composite inlays may have been improved, but it is still less than ideal. In clinically orientated studies, it is clearly demonstrated that the luting procedure is technically sensitive with all systems. The clinical experience is limited to only a few years, so to assess the longevity of adhesively luted inlays, more clinical studies must be done. However, tooth-colored inlays are the most esthetic, conservative restorations dentistry has ever offered its patients.

Composite Resins↗
PubMed1991

[Effects of dentin bonding agents on the proximal margins of ceramic inlays].

Ceramic inlays have shown good marginal seal as long as the margins of the cavities are located in enamel. The purpose of this study was to investigate the marginal seal of ceramic inlays with the cervical margins situated in dentin and to determine the effectiveness of dentin bonding agents. Sintered ceramic inlays were adhesively luted either without dentin bonding agents or with the use of Gluma or Miragebond. After thermocycling and incubation in a colored dye the penetration depth of the dye was measured on sequential sections. The used dentin bonding agents did not improve marginal seal. The glass ionomer cement base was able to prevent further penetration in most of the cases when deep leakage occurred. Unless a tight marginal seal in dentin can be achieved, the indication for adhesively luted inlays must be limited to cavities with margins located in enamel.

Ceramics↗
PubMed1991

[Opacity and opacity changes in composites].

The opacity of 5 self-curing and 11 light-curing composite resins was measured 24 hours after sample/preparation and after 6 months of storage (dry or in water) by means of an UV-visible spectrophotometer. The opacity of the investigated hybrid composite resins was between 47.3 and 62.4%. The opacity of the microfilled composite resins ranged from 48 to 64.4%. The opacity was not influenced by the polymerization time. The spectral opacity decreased with greater wavelengths, particularly in microfilled composite resins. All materials except Durafill, which became more translucent, were more opaque after 180 days of storage in water. Storage in water for 180 days caused greater changes of the opacity than dry storage for the same time. The opacity changes resulting from storage in water can be reduced by increasing the polymerization time.

Analysis of Variance↗
PubMed1991

Criteria for substituting amalgam with composite resins.

In recent years patients' aesthetic requirements have increased as knowledge of new materials and techniques has spread. Enamel etching and composite filling materials have enabled dentists to meet high functional and aesthetic standards in the placing of anterior and, latterly, posterior restorations. There has been a dramatic growth in the use of posterior composites and the aim of this paper is to provide the practising dentist with guidelines for the use of these materials.

Composite Resins↗
PubMed1991

Marginal adaptation with glass-ceramic inlays adhesively luted with glycerine gel.

The purpose of this study was to examine the effectiveness of glycerine gels in preventing the formation of an oxygen-inhibition layer during the polymerization of composite resin materials. Sixteen glass-ceramic inlays were adhesively luted with and without the application of glycerine gels on the inlay margins before the polymerization of the luting composite resin material. To remove the oxygen-inhibition layer, the inlays were brushed with acetone. Replicas were obtained before and after acetone brushing, and a computerized quantitative marginal analysis was carried out under the scanning electron microscope. Statistical analysis revealed significant differences between the polymerization with and the polymerization without the use of a glycerine gel. The inlay margins polymerized after the application of a glycerine gel showed better marginal adaptation than did the inlay margins polymerized without it, suggesting that oxygen inhibition during polymerization can be prevented by the application of glycerine gels to the surface of composite resin materials.

Ceramics↗
PubMed1990

[Effect of cavity design on the marginal fit of Class I composite fillings].

16 butt joint (Group A) and 16 beveled (Group B) class I cavities were prepared in extracted molars and filled with two hybrid composite resin materials using the enamel etching technique. Replicas were obtained before and after thermocycling (TC) and a computerized quantitative margin analysis was carried out in the SEM. Statistical analysis revealed significant differences (p less than 0.01) between the two groups only after TC. Group B showed significantly less marginal openings than Group A (A: 50.7%, B: 8.4%) after TC. Class I cavities for hybrid composite resin materials should be beveled.

Acid Etching, Dental↗
PubMed1989

[Opacity of composites and hard tooth substance on X-ray].

The opacity of eleven composites, enamel, and dentin was determined quantitatively using densitometric measurements of X-rays. The reference material was aluminium 99.5% which was exposed with each film. Opacity values were 215% for enamel and 118% for dentin. Three of the composite materials demonstrated an opacity similar to enamel, one similar to dentin. The other materials showed higher values than enamel. Consequently, the majority of composites reaches opacity values necessary for the diagnosis of secondary caries.

Composite Resins↗
PubMed1989

Quantitative margin analysis in the scanning electron microscope.

Interface between restorative materials and tooth hard substances must be morphologically as perfect as possible to avoid plaque accumulation and subsequent secondary caries or pulpal diseases. Therefore the marginal behavior of restorations is an important parameter to predict their longevity. Morphologically, the quality of margins is characterized by different well defined criteria. Using a replica technique it is possible to assess the complete marginal circumference of restorations in the SEM. Margins of restorations show a large variety of their morphology. This publication describes a method to quantify the quality of dental restorations. The restoration margins are traced on the SEM screen with a digitizer and an interface to measure the margin's length. Simultaneously the margin quality is assessed and assigned to the corresponding lengths. The % distribution of the quality criteria for each restoration is then calculated. Using a comparative light microscope, the replicas are aligned and mounted identically in the SEM for longitudinal studies. The results presented are limited to tests for the accuracy of the method. Using 5 criteria to characterize the margin quality, it was found that the difference between two measurements by the same operator, 4 weeks apart was 3% +/- 2.6%. The largest difference for one group was 9%. In another accuracy test where 4 criteria for margin characterization were used, the difference between two measurements was 1.9% +/- 0.9%. The largest difference between two groups found was 3.4%. This method can be used for longitudinal studies in vivo, but also for in vitro screening tests with new materials.

Dental Restoration, Permanent↗