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Comparative evaluation of polishing systems on the surface of three aesthetic materials.

This study compared the efficacy of three different polishing methods on a resin composite, a glass ionomer cement (GIC) and a compomer. Thirty samples of each material were prepared. Ten of them were randomly assigned to one of the three polishing methods. The surface roughness (Ra) of the samples were measured before and after the polishing procedure with a profilometer. There was no statistical difference between the composite and the compomer prior to polishing but statistical difference was found between the GIC and the two other materials. After polishing, the smoothest surfaces were obtained using Sof-Lex discs for the three materials, and the roughest surface, with tungsten carbide burs for the composite and the compomer, and with Enhance kit for the GIC. The composite gave the smoothest surface with the three methods.

Compomers↗

Surface roughness evaluation of resin modified glass-ionomers polished utilizing poly(acrylic acid) gel.

The differences in polishability of modified and conventional glass-ionomers were studied following different polishing procedures. Specimens of conventional glass-ionomer (Fuji II(R)), resin modified glass-ionomer (Vitremer(R)) and compomer (Dyract(R)) were prepared and polished using either Soflex(R) or Enhance(R) discs with either aluminum oxide or poly(acrylic acid) gel as polishing agents. Surface roughness of the specimens was evaluated by profilometric measurements and electron microscopic examination. It was shown that Soflex(R) discs manifest superior polishing effect on glass-ionomers and resin modified glass-ionomers compared to the Enhance(R) system, although no significant differences were found for the compomer specimens. Addition of poly(acrylic acid) gel as a polishing agent reduced surface roughness of conventional glass-ionomer and resin modified glass-ionomer specimens and did not significantly affect the compomer specimens.

Acrylic Resins↗

The effects of light intensity and method of exposure on the hardness of four light-cured dental restorative materials.

AIM: To determine the microhardness of several light-curing dental restorative materials at the top surface as well as at a depth of 2mm. METHODS: Comparisons were made using different light sources. Four groups of five specimens each (3mm diameter, 2mm thick) of Z250 (composite), Filtek Flow (flowable composite), Dyract AP (compomer) and Dyract Flow (flowable compomer) were cured using different methods of exposure. The curing lights used were a Spectrum 800 halogen curing light at settings of 800 mW/cm2 and 400 mW/cm2 and an Optilux 501 ramping light. Vickers microhardness tests were performed at the top surface and at the bottom surface. RESULTS: Significant differences in microhardness between the top and bottom surfaces were demonstrated for all materials and with all light sources (p<0.05). The different exposures also produced significant differences (p<0.05). The light source used had less of an effect on the hardness of the compomers than the composites. CONCLUSIONS: Effective hardness ratios between the top and bottom surfaces were achieved with all three curing protocols. The effect of total energy application must be taken into account before assumptions can be made as to the effect on hardness using different exposure methods.

Compomers↗

Direct restorative material use of selected practitioners in the United Kingdom.

PURPOSE OF THE INVESTIGATION: To investigate, by questionnaire, the direct restorative materials used by a sample of practitioners from the United Kingdom. BASIC PROCEDURES: A postal questionnaire was distributed to a group of self-selected practitioners, who volunteered to participate in the study. In all 110 practitioners participated in the study. MAIN FINDINGS: The most used material for the restoration of occlusal (Class I) and approximal (Class II) lesions was amalgam with 61% and 73% of practitioners indicating that they used amalgam in this situation. Adhesive tooth-coloured materials, specifically composites and compomers, were preferred by the majority of practitioners for anterior approximal (Class III) and incisal (Class IV) restorations with compomer preferred for Class V restorations including non-carious cervical lesions and for the restoration of primary teeth. PRINCIPAL CONCLUSIONS: It is concluded that the general practitioners surveyed in this study tend to use amalgam for the restoration of Class I and II lesions as opposed to resin composite. The majority of practitioners in this study used compomers, a relatively new group of restorative materials, with little evidence of traditional glass-ionomer cements being used routinely.

Adult↗

Flouride release from various restorative materials.

Fluoride release from six light-activated restorative materials, including two resinmodified glass-ionomers, two composites, and two compomers, was evaluated and compared with one conventional acid-based glass-ionomer cement. The amount and rate of release varied among the tested materials. Both resin-modified glass-ionomers and the conventional acid-base glass-ionomer cements released more fluoride then the composites and compomers (p < 0.05). Additionally, composite materials released less fluoride than compomer materials (p < 0.05). Release of fluoride by the tested materials showed a significant decrease after all the tested time intervals.

Acrylic Resins↗

Single-crystalline ceramic whisker-reinforced carboxylic acid-resin composites with fluoride release.

Currently available glass-ionomer, resin-modified glass-ionomer, and compomer materials have relatively low strength and toughness and, therefore, are inadequate for use in large stress-bearing posterior restorations. In the present study, ceramic single-crystalline whiskers were mixed with fluorosilicate glass particles and used as fillers to reinforce experimental carboxylic acid-resin composites. The carboxylic acid was a monofunctional methacryloxyethyl phthalate (MEP). Five mass fractions of whisker/(whisker + fluorosilicate glass), and corresponding resin (resin + MEP), were evaluated. Four control materials were also tested for comparison: a glass ionomer, a resin-modified glass ionomer, a compomer, and a hybrid composite resin. Flexural specimens were fabricated to measure the flexural strength, elastic modulus, and work-of-fracture (an indication of toughness). Fluoride release was measured by using a fluoride ion selective electrode. The properties of whisker composites depended on the whisker/(whisker + fluorosilicate glass) mass fraction. At a mass fraction of 0.8, the whisker composite had a flexural strength in MPa (mean +/- sd; n = 6) of 150 +/- 16, significantly higher than that of a glass ionomer (15 +/- 7) or a compomer control (89 +/- 18) (Tukey's multiple comparison test; family confidence coefficient = 0.95). Depending on the ratio of whisker:fluorosilicate glass, the whisker composites had a cumulative fluoride release up to 60% of that of a traditional glass ionomer. To conclude, combining ceramic whiskers and fluorosilicate glass in a carboxylic acid-resin matrix can result in fluoride-releasing composites with significantly improved mechanical properties.

Analysis of Variance↗

Restorative materials used on primary teeth: a comparative study between two European universities: Nice and Amsterdam.

A descriptive retrospective survey was carried in two European dental schools (UNSA - Nice and ACTA - Amsterdam), in order to compare the restorative materials used in deciduous dentition. Examination of 460 patient files showed that age and sex distribution among children in both cities was comparable. The dft scores were also comparable but the number of decayed teeth was higher in Nice (4.61 +/- 2.68) than in Amsterdam (2.86 +/- 2.30). In Nice, composite resins, compomers and glass ionomers were all used in deciduous anterior teeth whereas only compomers were used in Amsterdam. As far as deciduous molars were concerned, composite resins and amalgams were used on small and large cavities respectively in Nice whereas in Amsterdam, compomers were once again preferred.

Child↗

The influence of hygroscopic expansion of resin-based restorative materials on artificial gap reduction.

PURPOSE: This study compared the effect of water sorption on the extent of marginal gap reduction in two resin-modified glass-ionomer cements (RMGICs), two giomers, two compomers, and two resin composites over a twelve-week storage period. MATERIALS AND METHODS: Artificial gaps were created in 160 borosilicate glass cylinders. One-half of the internal surface of each cylinder was blocked out with wax and the other half was sandblasted. The bonding surface was further treated with 4% hydrofluoric acid, rinsed, and then coated with silane. After removal of the wax, one coat of dentin adhesive was applied to the silane-treated surface of the cylinder, briefly air dried and light cured. Eight light-cured restorative materials were placed incrementally: Vitremer (V), Fuji II LC (FJ), Beautifil (B), Reactmer Paste (R), Compoglass F (C), F2000 (F), Filtek Z250 (Z), and Tetric-Ceram (T). For each material, ten specimens were stored in deionized water (W), and ten (control) in nonaqueous silicone fluid (O) at 37 degrees C. The dimension of the same maximum gap created in each specimen was repeatedly measured at 0, 1, 2, 4, 6, 8, 10, and 12 weeks. RESULTS: R-W exhibited extensive hygroscopic expansion that resulted in cracking of 40% of glass cylinders after the 2nd week and 70% after the 4th week. One-way ANOVA of the other seven water groups showed significant differences (p < 0.001) among gap widths measured at different time intervals in V-W, FJ-W, C-W, F-W. Both RMGICs had the most significant gap reduction during the first week (p < 0.001). Both compomers exhibited delayed water-sorption characteristics, with more significant gap reduction observed in C-W. B-W was similar to the two resin composites Z-W and T-W and exhibited the least gap reduction. After the first week, there were no significant differences in the percentage reduction in marginal gaps for any of the groups (p > 0.05). CONCLUSION: Marginal gap reduction that results from water sorption is more extensive and rapid in RMG-ICs, followed by compomers, whereas composites are relatively stable. Reactmer Paste exhibits rapid and extensive expansion and should probably be avoided in tooth preparations that involve thin unsupported enamel.

Acid Etching, Dental↗

Dentin/enamel adhesives in pediatric dentistry.

The improvements in adhesives and composite technology have made resin-based composite resins and polyacid-modified resin-based composites (compomers) very popular as materials to restore primary and permanent anterior and posterior teeth. More conservative preparations can be performed maintaining more tooth structure due to the adhesive properties of the adhesives used with composites and compomers. Meticulous care in the placement of adhesives and, subsequently, resin-based composites and compomers is necessary to produce long-term satisfactory results.

Acid Etching, Dental↗

Fluoride, hydrogen ion and HEMA release from light-cured GIC restoratives.

PURPOSE: To quantitatively measure the amount of fluoride, hydroxy ion and hydroxyethyl methacrylate (HEMA) released from various light-cured restorative materials. MATERIALS AND METHODS: Three resin-modified glass-ionomer cements (RMGI): Photac-Fil Aplicap, Vitremer, and Fuji II LC and two polyacid-modified resin-based composites (compomer): Dyract and Variglass VLC were used in this study. Disc-shaped specimens were made as per manufacturer's recommendations and the surfaces were polished with a 600 grit abrasive paper. Immediately after setting, each disc was immersed into 10 ml of distilled water at 37 degrees C and the eluates were collected after 8- or 24-hour immersion. The concentration of HEMA in the eluate was determined by high performance liquid chromatography. In addition, the concentration of fluoride ion and pH were measured by the respective ion selective electrode. RESULTS: The RMGIs released the greater amount of fluoride and smaller amounts of HEMA compared to the compomers at both the 8- and 24-hour eluates. Although there were no significant differences in pH of the 8-hour eluates among the restoratives, the pHs of the RMGI were significantly higher than those of the compomers for the 24-hour eluates.

Acrylic Resins↗

One-year evaluation of atraumatic restorative treatment and minimum intervention techniques on primary teeth.

Atraumatic restorative treatment (ART) and minimal intervention treatment (MIT) techniques were evaluated under field conditions in 5 regions of the Western Cape Province of South Africa, where caries prevalence exceeds 60% and remains mostly untreated. The purpose of the study was to compare and evaluate results of ART and MIT techniques in the primary dentition of 6-9 year-old schoolchildren using glass-ionomer (GI) (Fuji IX) and compomer (Dyract AP) materials. At baseline 401 children were treated, and 1,119 restorations placed by 5 calibrated dentists, 53% with ART (using hand instruments only) and 47% with MIT (minimal use of slow hand-piece) techniques. Evaluations were done with a CPI periodontal probe to measure marginal defects and to detect decay. A pain assessment for the restoration procedures indicated that 80% of subjects experienced no pain, 18% discomfort and slight pain, and 2% required local anaesthetic. After one year 90.5% of subjects and 80% of restorations were followed up (11.1% lost as a result of exfoliation); of these restorations 86% were clinically acceptable (84.1% of the ART and 88% of the MIT). With the art technique 82.7% of GI restorations and 85.6%, of compomer restorations were acceptable. With the MIT technique 86.5% of GI restorations and 89.9% of compomer restorations were acceptable. Success of restorations per region varied significantly: regions 1 and 2-90%, region 3-80%, region 4-70% and region 5-95%. There were no significant statistical differences in respect of materials or methods employed. ART and MIT techniques were well accepted as complementary caries approaches by operators. One-year results show that ART and MIT techniques were successful, substantiating its use for the primary dentition in areas with high caries prevalence. Longer-term assessments are required.

Anesthesia, Dental↗

Linear displacement and force induced by polymerization shrinkage of resin-based restorative materials.

PURPOSE: To measure the linear displacement and force induced by polymerization shrinkage of a series of resin-based restorative materials. METHODS: The materials tested were 10 ultrafine midway-filled resin-based composites, mainly used in anterior restorations (Brilliant Dentin, Brilliant Enamel, Charisma F, Pertac II Aplitip, Prodigy, Resulcin, Sculpt-it, Synergy Duo, Tetric and Z100), 11 ultrafine compact-filled composites, suggested by the manufacturers as "amalgam substitutes" for posterior restorations (Alert, Ariston pHc, Definite, EXI-119, EXI-120, Nulite F, Prodigy Condensed, Prodigy High Viscosity, Solotaire, Surefil and Synergy Compact), and six polyacid-modified composites (Compoglass, Dyract, Dyract AP, Elan, F2000 and Hytac Aplitip), also known as compomers. Each property was measured for 180 seconds from the start of curing with the help of custom made devices in eight specimens for each material. Statistical evaluation of the data was performed with one-way ANOVA, Tukey's Studentized Range (HSD) Test (P= 0.05) and simple linear regression. RESULTS: Statistically significant differences among groups and among composites were found for both of the properties that were studied. The ultrafine compact-filled composites (amalgam substitutes) exhibited the least linear displacement, followed by the polyacid-modified composites (compomers) and the ultrafine midway-filled composites, with statistically significant differences among all groups. The groups followed the same order in the polymerization force, with only the compomer-amalgam substitute comparison not being statistically significantly different. The simple linear regression showed that the two studied properties were also highly correlated (r=0.89).

Analysis of Variance↗

[Effect of saliva contamination on microleakage around class-5 cavities restored with three different types of adhesive materials].

The recent improvement of adhesive materials should decrease the risk related to saliva contamination. The aim of this study was to evaluate the effect of saliva contamination on the microleakage within class V cavities restored with three different types of materials: conventional glass ionomer cement, composite resin and compomer. 30 human extracted teeth were randomly divided in 3 equal groups. In each group, class V cavities were prepared on both facial and lingual surfaces (but joint for glass ionomer cement and bevelled incisal margin for composite resin and compomer). The lingual cavities were contaminated with saliva prior to restoration, while the facial cavities were not contaminated, serving as control. After water storage for 24 hours, teeth were immersed in 1% methylene blue solution for 24 hours. The axial sections were viewed under an optical microscope and the extent of dye penetration along cervical, axial and incisal margins was measured in millimetres. Statistic analysis showed that under salivary contamination, microleakage increased along the cervical margin of restoration for all three tested materials. Saliva contamination resulted in microleakage within the axial wall of the cavity only for the conventional glass ionomer cement. These data indicate that composite resin and compomer used together with new adhesives seem to be less sensitive to saliva contamination compared to conventional materials. However, under saliva contamination, cervical microleakage cannot be completely prevented and proper isolation should still be mandatory.

Adhesives↗

Longevity of occlusally-stressed restorations in posterior primary teeth.

PURPOSE: To compile a survey of the longevity and reasons for failure of stainless steel crowns, amalgam, glass-ionomer, composite and compomer restorations in stress-bearing cavities of primary molars. METHODS: This work reviewed the dental literature of 1971 up to July 2003 for longitudinal, controlled clinical studies and retrospective cross-sectional studies. Only studies investigating the clinical performance of restorations in primary teeth with an observation period of at least 2 years were included. Annual failure rates of stainless steel crowns, amalgam, glass-ionomer, composite and compomer restorations were determined and failure reasons were discussed. RESULTS: Annual failure rates in stress-bearing cavities of primary molars were determined to be: 0-14% for stainless steel crowns, 0-35.3% for amalgam restorations, 0-25.8% for glass-ionomer restorations, 2-29.1% for atraumatic restorative treatments, 0-15% for composite restorations, and 0-11 for compomer restorations. Main reasons for failure were secondary caries, marginal deficiencies, fracture, and wear.

Compomers↗

Measurement of water sorption in dental composites.

This study measures the changes in dimension and weight resulting from water sorption in light-cured resin-based materials using an innovative computer-controlled laser micrometer and a precision digital balance. Three materials are examined in this study: a micro-filled composite, a dual-cure luting composite and a compomer. Five discs of each test material were prepared, weighed and the size of each disc was measured across sequential diameters by a computer-controlled laser micrometer. Measurements were carried out at intervals over a 24-month period. Significant changes in the rate of percentage weight gain and the rate of percentage linear expansion occurred for up to 90 days for the composite restorative and the luting material and up to 150 days for the compomer. This study concludes that over a period of 24 months, the hygroscopic expansion of the compomer material is significantly greater than that of the conventional composites tested.

Absorption↗

Influence of patient factors on age of restorations at failure and reasons for their placement and replacement.

OBJECTIVE: This study examined the reasons given by a selected group of dental practitioners for placement and replacement of restorations and correlated the data provided with patient factors, such as patients' age and gender, caries risk, occlusal function and oral hygiene, with restoration longevity. METHOD: A group of general dental practitioners (GDPs) were recruited to take part in the study. Each participant was asked to record the reason for placement or replacement of restorations from a list of potential reasons. The age and Class of the restoration being replaced was also recorded, as also was the material being used and the material being replaced. RESULTS: Details of reason for placement/replacement was received on 3196 restorations from 32 GDPs. Of the restorations placed, 54% were amalgam, 32% composite, 8% compomer and 7% glass ionomer. The reasons for placement/replacement of the restorations were principally primary caries (28%), secondary caries (29%), margin fracture (10%), tooth fracture (7%), and non-carious defects (6%). Overall, the mean age of restorations at failure was 7.1 years. Of the patients who received glass ionomer restorations, 29% were rated as having poor oral hygiene, compared with 18% of the patients who received amalgam restorations, 18% of the patients who received composite restorations and 23% of the patients who received compomer restorations. Of the patients who received glass ionomer restorations, 35% were rated as having high caries susceptibility, compared with 27% of those receiving amalgam restorations, 21% of those receiving composite restorations and 30% of those receiving compomer restorations. CONCLUSION: Primary caries was the principal reason for initial restorations. Secondary caries was the most prevalent reason for replacement of restorations. The results also indicate a selective application of different materials for different patients.

Adolescent↗

Water sorption and water-induced molecular mobility in dental composite resins.

Water sorption in two resin composites, Kulzer's Solitaire (S) and SDI's Wave (W), and in a polyacid-modified composite resin, 3M's F2000 (compomer F), was investigated by means of equilibrium sorption isotherms (ESI) and of dynamic sorption (DS) measurements. Molecular mobility in these materials was studied by means of dielectric relaxation spectroscopy (DRS) and of thermally stimulated depolarization currents (TSDC) measurements. The results of ESI measurements show that at equilibrium, water is molecularly distributed in the materials and the effects of hydrophilic sites and clustering are negligible. Hysteresis effects in sorption-desorption cycles are larger in the resin composites than in the compomer. Equilibrium water uptakes in both ESI and DS conditions are rather low, in the range 1-2%. Diffusion coefficients of water are about 1x10(-8) cm(2)/s in the resin composites and by a factor of about 2 smaller in the compomer. Molecular mobility increases with hydration, as suggested by preliminary DRS and TSDC measurements. Detailed dielectric measurements may give important information for understanding, at the molecular level, water-induced degradation in dental materials.

Journal Article↗

A clinical evaluation of a resin-modified. Glass ionomer restorative material.

Compomers, resin-modified glass ionomers, were developed to improve the physical properties and clinical handling of glass ionomers. Compomers can be designed to be light-activated and used as restoratives or liners. This article reports data collected up to 12 months after placement of both compomer restorations and liners and is part of an ongoing study evaluating the performance of this material. Based on this data, the authors conclude that this new generation of light-activated glass-ionomer restoratives provides clinical results comparable to those recorded for composite resins at 12 months.

Acrylic Resins↗