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At least 19 recordsLinked to original sources
PubMed2005

The use of Ormocer as an alternative material for bonding orthodontic brackets.

As new adhesives, composite resins, and bonding techniques were introduced, orthodontists adopted some of these innovations and added them to their armamentarium. The purpose of this study was to compare the shear bond strength (SBS) of two adhesive materials; one with an organically modified ceramic matrix, Admira (Voco, Cuxhaven, Germany) and another that contains the traditional Bis GMA matrix namely Transbond XT (3M Unitek, Monrovia, Calif). The new materials have a lower wear rate and are more biocompatible than traditional composites. Forty molar teeth were randomly divided into two groups: 20 teeth bonded with the Transbond adhesive system and the other 20 teeth with the Admira bonding system. Student's t-test was used to compare the SBS of the two adhesives. Significance was predetermined at P < or = .05. The results of the t-test comparisons (t = 0.489) of the SBS indicated that there was no significant (P = .628) difference between the two adhesives tested. The mean SBS for Admira was 5.1 +/- 3.3 MPa and that for Transbond XT was 4.6 +/- 3.2 MPa. It was concluded that the new material, Ormocer, which is an organically modified ceramic restorative material can potentially have orthodontic applications if available in a more flowable paste. These new materials are more biocompatible and have lower wear rate including bonding orthodontic brackets to teeth.

Ceramics↗
PubMed2004

Surface roughness of nanofill and nanohybrid composite resin and ormocer-based tooth-colored restorative materials after several finishing and polishing procedures.

The purpose of this study was to evaluate the effect of several finishing and polishing procedures on the surface roughness of nanofill and nanohybrid composites and ormocer-based dental restorative materials. The materials included a nanofill composite (Supreme); a nanohybrid composite (Grandio); and an ormocer (organically modified ceramic) (Admira). Forty specimens of each material were prepared using a Mylar strip (polyester strip) and randomly divided into four finishing and polishing groups (n =10): (I) Diamond bur/Super-snap Rainbow Technique Kit(Al(2)O(2)-coated, graded abrasive discs); (II) Diamond bur/Astropol and Astrobrush system (silicone abrasive polishers and brush system); (III) Tungsten carbide bur/Super-snap Rainbow Technique Kit; and (IV) Tungsten carbide bur/Astropol and Astro-brush system. The average surface roughness (Ra) in micrometers was measured using a "Mahr Perthometer S4P" Surface Roughness Tester and the data were compared using ANOVA at P <or=0.05. The results of this study indicated that the Mylar strip produced the smoothest surface on all materials and among the finishing-polishing methods the first and the third methods performed significantly smoother surfaces than the second and the fourth methods for the three restoratives. Ormocer (Admira) performed the lowest variability in initial surface roughness among the tested materials. This study has shown that Super-snap abrasive discs produced a smoother surface than the Astropol and Astrobrush silicone polishers for composite and ormocer-based restorative materials, but the results would be valid clinically for readily accessible and flat surfaces i.e., not for all areas in the mouth. Therefore silicone polishers are necessary for posterior areas and for concave and convex surfaces.

Ceramics↗
PubMed2004

The effect of pulse activation on microleakage of a 'packable' composite resin and two 'ormocers'.

The purpose of the study was to examine the effect of pulse polymerization on microleakage of one packable composite resin and two organically modified ceramics (ormocers), within a high C-factor preparation. Class-V cavity preparations with occlusal margins in enamel and gingival margins in dentin were prepared on 60 freshly extracted premolars or molars. Teeth were randomly assigned to 12 experimental groups (five teeth each) representing the different restorative systems, mode of polymerization and thermal cycling test. Three groups of 20 teeth each were restored with one of the following restorative systems: Scotch bond 1/Filtek P 60, Admira bond/Admira, Etch&Prime 3.0/Definite. 10 restorations of each restorative system (two experimental groups) were conventionally polymerized, whereas the other 10 restorations were polymerized with a pulse program. The specimens were stored in double-distilled water at 37 degrees C for 24 h. Ten restorations from each restorative system (30 restorations, half of the specimens) were thermocycled, the other 30 restorations were kept in double-distilled water at 37 degrees C for 24 h. Then all 60 restorations stained with dye, sectioned and scored for microleakage. Results showed that there were no significant differences (P > 0.05) among the materials with respect to microleakage scores. The experimental groups that were conventionally polymerized revealed significantly more microleakage (P < 0.05) after thermal cycling than all the other groups. The gingival microleakage was significantly more (P < 0.05) than occlusal in conventionally polymerized, thermocycled experimental groups.

Bicuspid↗
PubMed1999

In vitro cytotoxicity of resin-containing restorative materials after aging in artificial saliva.

Studies have reported that dental resin-based materials release substances which have biological liabilities. However, some current methods for detecting these substances may not be adequate to detect biologically relevant concentrations. In the current study, we hypothesized that resin-based materials exhibit cytotoxic effects and alter cellular function in vitro when high-pressure liquid chromatography (HPLC-UV detection) cannot detect any release of substances. We further hypothesized that this release continues even after aging the samples in artificial saliva. Five types of composite or compomer materials (Z-100, Tetric Ceram, Dyract AP, Solitaire, and Clearfil AP-X) and one organically modified ceramic material (Definite) were tested after aging in artificial saliva for 0, 7, or 14 days. Cytotoxicity was assessed using direct contact with fibroblasts and measurement of succinic dehydrogenase activity after 48 h of exposure post aging. Release of substances from the materials was assessed using HPLC with UV detection. Altered cellular function was estimated by measuring proliferation of MCF-7 cells with sulforhodamine staining. HPLC showed that whereas initial release of substances was higher without aging, this release dropped significantly after 7 or 14 days of aging, and was equivalent to the Teflon controls after 14 days for four of the materials (Tetric Ceram, Definite, Solitaire, and Clearfil AP-X). Without aging in saliva, all materials had cytotoxicities > 50% of the Teflon negative controls. After 14 days of aging, all materials except the Definite continued to show severe cytotoxicity. Only the Definite could be tested for its ability to alter cellular function because of the continuing toxicity of the other materials. This modified ceramic material caused a significant proliferative effect on the MCF-7 cells indicating that sufficient substances were released to alter cellular function. We concluded that all of these commercially available resin-based dental materials continue to release sufficient components to cause lethal effects or alter cellular function in vitro even after 2 weeks of aging in artificial saliva.

Analysis of Variance↗
PubMed2001

The suitability of packable resin-based composites for posterior restorations.

BACKGROUND: Packable composites, promoted for the restoration of stress-bearing posterior teeth, have captured clinicians' interest. METHODS: The authors tested three packable composites (Alert, Jeneric/Pentron; Solitaire, Heraeus Kulzer, Wehrheim, Germany; SureFil, Dentsply De Trey, Konstanz, Germany); a new packable organically modified ceramic, or ormocer (Definite, Degussa AG, Hanau, Germany); a hybrid composite (Tetric Ceram, Ivoclar Vivadent, Schaan, Liechtenstein) and an ion-releasing composite (Ariston pHc, Ivoclar Vivadent, Schaan, Liechtenstein). They determined modulus of elasticity according to EN 24049:1993 of the European Committee for Standardization. They measured Vickers hardness using a 200-gram load for 40 seconds. To determine the materials' depth of cure, they used both a scraping method (International Standards Organization standard CD 4049:1997) and a hardness profiling method. RESULTS: The authors calculated means and standard deviations from 10 replications of each test and used one-way analysis of variance and post hoc Tukey tests (alpha = .05). The materials had significant differences (P < .001) in all characteristics. Solitaire had the significantly lowest elastic modulus and microhardness; Alert had the highest values for these characteristics. Ariston pHc exhibited the significantly lowest depth of cure. There was a significant correlation between the two methods of measuring depth of cure (r2 = 0.9945; P = .021). CONCLUSIONS: The material group of packable composites is rather inhomogeneous in terms of mechanical and physical data. Our data suggest that bulk curing of packable composites in deep cavities still is not recommendable. CLINICAL IMPLICATIONS: The clinician needs to select packable composites carefully, as it seems that not all of these materials quality for stress-loaded posterior restorations.

Analysis of Variance↗
PubMed2004

Tooth-composite interface from specific and nonspecific adhesive restorative systems.

The aim of this in vitro study was to do a morphological comparison of tooth/composite interface by means of three composite systems: (1) a specific formulated primer adhesive and Organically Modified Ceramics (ORMOCER) composite, (2) an universal self-etching adhesive and the same ORMOCER composite, (3) and the same universal adhesive used for Group 2 and a fine-particle hybrid resin composite. The rational for this study was based on the recommendations from manufacturers that nonspecific dentin bonding agents can be used with ORMOCER. Twenty-one Class II cavities were prepared in extracted third molars. Seven randomly assigned teeth were restored with one of the three methods according to the instructions provided by the manufacturer. Following completion of the restorations, the teeth were sectioned and evaluated by means of scanning electron microscopy for evaluation of interfacial morphology and light microscopy for the determination of microleakage. The last was scored as being present or absent. The best results were observed using method 1, in which a special primer adhesive and ORMOCER composite was used. In this group there were statistically significant fewer gaps in enamel (4.7+/- 7.5%) and dentin (22.8 +/- 7.4%) compared to the other two groups (Group 2: enamel 21.1 +/- 8.3% and dentin 66.3 +/- 17.3%; and Group 3: enamel 40.6 +/- 35.2% and dentin 89.4 +/- 13.3%). The interfaceof method 2, universal self-etching adhesive and ORMOCER, was of a lesser quality than Group 1. Within the limitations of this study the recommendation is made to use the ORMOCER tested in this experiment with the matching specifically formulated primer adhesive system. A lack of adhesion as well as microleakage, were prominent features for Groups 2 and 3. From the data of this study the practitioner is cautioned not to indiscriminately exchange specific dentin bonding agents for nonspecific ones. Considering the shear endless number of possible combinations and the numerous different tests that would be required to test these all, selection of different combinations will remain a theoretical exercise.

Acrylic Resins↗
PubMed2003

Hygroscopic expansion and solubility of composite restoratives.

OBJECTIVE: To quantify the changes of dimension (vol%), weight (microgram/mm(3)) and the solubility (microgram/mm(3)) of dental composite restorative materials after a period of 64 days immersed in de-ionized water or artificial saliva. METHOD: Six resin-based composite restorative materials were investigated. An organically modified ceramic (Definite((R))), an ion-leaching composite (Ariston pHc((R))), two high-density packable composites (Solitaire((R)) and SureFil((R))) and two sub-micron hybrid composites (Pertac II((R)) and Spectrum TPH((R))). Twelve disks of each test material were prepared, 10mm diameter by 1mm thickness. All specimens were kept dry for 48h during polymerization. Two control specimens of each group were kept in a desiccating chamber; five specimens in de-ionized water and five specimens in artificial saliva (Salivace((R)), Penn) at 37 degrees C. The diameter of each disc was measured automatically across 200 points by rotation through beam of a laser micrometer. These measurements, together with weight measurements, were carried out at intervals over a 64 day period. The equilibrium value at time infinity, the rate of change and the equilibrium solubility was calculated for each material. RESULTS: At 64 days, the mean dimensional change (vol%) after water immersion ranged between 0.15% (+/-0.05) for Pertac II((R)) to 2.39% (+/-0.6) for Ariston pHc((R)). Dimensional changes (vol%) values for specimens immersed in artificial saliva were significantly different only for the material Solitaire((R)) (p<0.05). Change in weight (microgram/mm(3)) values were significantly different (p<0.05), according to the immersing solution for the materials Solitarie((R)), Ariston pHc((R)) and Surefil((R)) At 64 days, all specimens gained weight with the exception of the material Ariston pHc((R)) that lost 20.57 microgram/mm(3) (+/-6.46). Only the specimens immersed in de-ionized water showed any significant dissolution of the material, with solubility values ranging up to 32.5 microgram/mm(3) (+/-2.7) for Ariston pHc((R)). SIGNIFICANCE: Currently available dental composite materials vary significantly in the post-placement expansion behavior demonstrating a lack of consensus view amongst developers as to the most desirable values that should be attained. The nature of the immersing solution in in vitro studies of this nature has a distinct effect on the results obtained for some materials.

Absorption↗
PubMed2002

Long-term cytotoxicity of resin-based dental restorative materials.

Highly filled composites, Ormocers (organically modified ceramics) and 'smart' materials have been developed to overcome the polymerization shrinkage problems of conventional composite materials. The purpose of the current study was to investigate the effect of longer-term (up to 8 weeks) ageing of these resin-based dental restorative materials and determine the effect of post-curing on cytotoxicity. Twelve discs of each material (Colombus/IDR, Definite/Degussa, Ariston pHc/Vivadent) were either light-cured (Lc) or light-cured and post-cured (Pc). For cytotoxicity testing, the discs were placed in contact with cell culture medium (DMEM) and incubated at 37 degrees C. Extracts from composite materials were collected after 24 h and weekly over a time period of 8 weeks. Cytotoxicity of the eluates to cultured fibroblasts (Balb/c3T3) were measured by the succinic dehydrogenase (SDH) activity (MTT assay) and the results expressed in percentage of negative controls (Teflon discs). The results showed that ageing significantly influenced the cytotoxicity of the materials. Except for Ariston pHc, materials were less cytotoxic after 8 weeks of ageing than they were in early intervals and post-curing was not generally useful in reducing cytotoxicity. The Ariston pHc was initially moderately toxic, but then become highly cytotoxic for 5 weeks before returning to initial levels. The current study demonstrated the importance of assessing the cytotoxicity of resin composite materials at multiple times.

3T3 Cells↗
PubMed2003

Effect of finishing and polishing procedures on the surface roughness of new tooth-coloured restoratives.

The purpose of this study was to evaluate the effect of various finishing and polishing procedures on the surface roughness of three new tooth-coloured restorative materials. The materials included a hybrid composite resin (Filtek Z250), a packable composite resin (Filtek P60), and an ormocer (organically modified ceramic) (Definite). Thirty-two specimens of each material were prepared and randomly divided into four finishing and polishing groups (n = 8): (i) diamond bur/silicone polishers, (ii) diamond bur/Sof-Lex discs, (iii) carbide bur/silicone polishers, (iv) carbide bur/Sof-Lex discs. Average surface roughness (Ra) in micrometers was measured with a Mitutoyo Surftest-402 Surface Roughness Tester and the data compared using anova, at P < or = 0.05. Surface topography was also assessed using the scanning electron microscope (s.e.m) from samples of each group. The Mylar strip produced the smoothest surface and finishing/polishing procedures; (ii) and (iv) were significantly smoother than (i) and (iii). The lowest variability in initial surface roughness between materials was also observed with ormocer group.

Composite Resins↗
PubMedDate not supplied

Microleakage of different resin composite types.

OBJECTIVE: The purpose of this study was to evaluate the microleakage of Class V cavity preparations restored with three different types of resin composite and an ormocer. METHOD AND MATERIALS: Forty Class V cavities were prepared in buccal and lingual surfaces of 20 recently extracted molar teeth. The occlusal margin of each restoration was on enamel and the gingival margin on dentin. Teeth were randomly assigned to four groups of 5 teeth each and restored as follows: Group I, flowable resin composite (Tetric Flow); Group II, hybrid resin composite (Z100); Group III, packable resin composite (Solitaire 2); Group IV, organically modified ceramics-ormocer (Admira). In all groups, the manufacturers' instructions were strictly followed. All restorative resin composite materials were placed in one increment. All teeth were then immersed in 0.5% basic fuchsin solution for 24 hours after thermocycling (200 cycles; between 4 degrees C to 60 degrees C). The teeth then were longitudinally sectioned and observed under a stereomicroscope. The degree of dye penetration was recorded and analyzed with the Kruskal-Wallis and Mann-Whitney tests. RESULTS: No statistically significant differences in microleakage were observed between groups either on enamel or dentin. CONCLUSION: All restorative materials demonstrated equal effectiveness in reducing microleakage.

Ceramics↗
PubMedDate not supplied

Wear behavior of new composite restoratives.

This study investigated the wear resistance of recently introduced nanofill (Filtek Supreme [FS], 3M-ESPE) and ormocer (Admira [AM], Voco) composites and compared their wear characteristics to microfill (Filtek A110 [AO], 3M-ESPE]), minifill (Esthet X [EX], Dentsply; Filtek Z250 [ZT], 3M-ESPE) and polyacid-modified (Dyract AP [DY], Dentsply) composites. Six specimens were made for each material. The specimens were conditioned for one week in distilled water at 37 degrees C and subjected to wear testing at 20 MPa contact stress against SS304 counter-bodies using reciprocal compression-sliding wear instrumentation. Distilled water was used as lubricant. Wear depth (microm) was measured using profilometry every 5,000 cycles up to 20,000 cycles. The results were analyzed using ANOVA/Scheffe's test (p<0.05). Wear of the materials was cycle and fatigue dependent. Although no significance in wear was observed between materials after 5,000 cycles of wear testing, significant differences were observed at 10,000 cycles and greater. After 20,000 cycles of wear testing, ranking was as follows: ZT > DY >AM > AO > FS > EX. Wear ranged from 39.90 microm for EX to 113.32 microm for ZT. The wear resistance of ZT and DY was significantly lower than AO, FS and EX In addition, ZT experienced significantly more wear than AM. Under the conditions of this in-vitro study, the wear resistance of nanofill and ormocer composites was comparable or superior to polyacid-modified, microfill and minifill composites.

Analysis of Variance↗
PubMed2005

Effect of two different bleaching regimens on the gloss of tooth colored restorative materials.

OBJECTIVES: Vital tooth bleaching with peroxide is one of the most common cosmetic procedures in dentistry and can be accomplished using a variety of methods or regimens. Recently, new generation of tooth color restorative materials were introduced to market. The purpose of this in vitro study was to determine the gloss changes of three different tooth color restorative materials: Flowable composite (Filtek Flow/3M), packable composite (Filtek P60/3M) and ormocer (Definite/DEGUSSA) after two different bleaching regimens (Vivastyle/VIVADENT) and (Crest Professional Whitestrips/PROCTER and GAMBLE). METHODS: 16 specimens 30 x 30 x 2 mm size were fabricated from each restorative material. After gloss values were measured with gloss meter, at two different angles of illumination (20 and 60 degrees ), 10% carbamide peroxide (Vivastyle) was applied for 2 h per day for fourteen days to the half of the specimens while 6.5% hydrogen peroxide strip bands (Crest Professional Whitestrips) were applied to the remaining eight of the specimens for 30 min twice daily for 14 days. During the test period the specimens were stored in 37 degrees C and 100% relative humidity. At the end of bleaching regimen the gloss measurements were repeated and the data were subjected to statistical analysis. RESULTS: The Wilcoxon Signed Rank Test analysis revealed that the gloss values were affected by both bleaching regimens (P=0.012). Whitestrips decreased the gloss values of Filtek P60 (at 20 and 60 degrees , P<0.001) and Filtek Flow (at 20 degrees , P=0.05 and at 60 degrees , P=0.05) significantly compared to Vivastyle, while the gloss values of Definite did not show any significant change between Vivastyle and Whitestrips application (at 20 degrees P=0.279; at 60 degrees , P=0.279, Mann-Whitney U Test). The gloss values of materials were significantly different before (at 20 degrees P<0.001; at 60 degrees , P=0.003) and after bleaching (at 20 degrees P<0.05; at 60 degrees , P<0.05) with the highest value of Filtek Flow followed Filtek P60 and then by Definite (Kruskal Wallis test). SIGNIFICANCE: As the gloss of tooth colored restorative materials could be affected by bleaching regimens, it is necessary to consider the type of the material before starting the treatment.

Carbamide Peroxide↗
PubMed2005

Influence of initial water content on the subsequent water sorption and solubility behavior in restorative polymers.

PURPOSE: To evaluate the water sorption characteristics and solubility behavior of two resin-based composites, an ormocer, a compomer and a resin-modified glass-ionomer, according to ISO 4049 specifications and also without the initial desiccation cycle. METHODS: After polymerization, five disks (15 x 1 mm) of each material [Filtek P60 (P60), Solitaire 2 (SOL2), Admira (ADM), Compoglass F (COF) and Fuji II LC (FLC)] were desiccated until a constant mass (ml) was obtained. They were immersed in distilled water for 7 days and immediately weighed after that period (mass m2). Then disks were again desiccated and weighed every day for 35 days (mass m3). Sorption and solubility values were deduced from these different measures. Without initial desiccation mass m1 was obtained just after polymerization. RESULTS: Without initial desiccation, all the materials absorbed less water and solubility was 1.5 to 8 times greater than in standard experiment. For the two protocols, water sorption and solubility were significantly greater in FLC, and ADM showed the least weight loss of all the materials tested.

Absorption↗
PubMedDate not supplied

Wear and microhardness of different resin composite materials.

This study determined the three-body abrasive wear resistance of two packable composites (P-60; Solitaire 2), an ion-releasing composite (Ariston AT), a hybrid composite (Tetric Ceram) and an ormocer (Admira). The study also looked at the correlation between wear resistance and hardness of the composites. Three-body wear testing was performed using an ACTA wear machine with 15 N contact force using millet seed as the third body. Wear depth (microm) was measured by profilometry after 200,000 cycles. The hardness test was performed using a digital microhardness tester (load: 500 g; dwell time: 15 seconds). The data were analyzed by using Kruskal Wallis (p < 0.05). There were statistically significant differences among the three body abrasive wear of the composites. The ranking from least to most were as follows: Filtek P-60 < Solitaire 2 < Ariston AT < Tetric Ceram < Admira. Filtek P-60 showed the highest microhardness value. No other significant differences in hardness were observed among the different resin composites (P-60 > AristonAT = Tetric Ceram = Solitaire 2 = Admira). The results of this study indicate that there are significant differences in the wear resistance of the resin composites. The correlation between hardness and wear was significant with a correlation coefficient of r:-0.91. A significant negative correlation exists between hardness and three-body wear of resin composites.

Analysis of Variance↗
PubMed2004

Marginal and internal adaptation of Class II ormocer and hybrid resin composite restorations before and after load cycling.

To overcome the shortcomings of the conventional composite restorative materials, ormocer materials have been introduced over the past few years. The purpose of this study was to evaluate the marginal and internal adaptation of two ormocer restorative systems (Admira, Voco and Definite, Degussa) compared to a hybrid composite one (TPH Spectrum, Dentsply/ DeTrey), before and after load cycling in Class II restorations. Standardized Class II restorations with cervical margins on enamel were divided into three groups ( n=16). Teeth of each group were filled with one of the restoratives tested and its respective bonding agent. Each group was divided into two equal subgroups. The marginal and internal adaptation of the first subgroup was evaluated after 7-day water storage at room temperature and of the second after cyclic loading in a mastication simulator (1.2x10(6) cycles, 49 N, 1.6 Hz). The occlusal and cervical marginal evaluation was conducted by videomicroscope and ranked as "excellent" and "not excellent". One thin section (150 microm), in mesial-distal direction, of each restoration, was examined under metallographic microscope to determine the quality of internal adaptation. The occlusal and cervical adaptation of both ormocer restorative systems was similar and clearly worse compared with the hybrid composite restorative one before as well as after load cycling. Concerning internal adaptation, no gap-free ormocer restorations were detected, whereas all Spectrum restorations presented perfect adaptation. The bonding agents of the ormocers formed layers with unacceptable features (pores, fractures) whereas that of the hybrid composite achieved perfect bonding layer even after loading. The rheological characteristics of the bonding agents of the ormocer restorative systems are proposed to be responsible for their inferior marginal and internal quality in Class II restorations compared with the hybrid composite one.

Ceramics↗
PubMed2003

Abrasive effect of brushing on ormocers following acid conditioning.

The purpose of this study was to evaluate the effect of toothbrushing on the surface roughness and microhardness of Admira and Definite following acid conditioning. Half of the samples were either used as controls or brushed for 10 minutes using an electric toothbrush with slurry. The remaining specimens were stored in orthophosphoric acid with a pH of 1.9 for 24 hours and then half were brushed. The surface roughness of Admira and Definite was not significantly affected by storage under acidic conditions. However, the specimens of both materials in the control groups and the ones tested after acidic storage were found to be significantly smoother than the specimens subjected to toothbrushing alone and brushing following acid conditioning. For both materials, significantly higher values of microhardness were obtained after toothbrushing following acid conditioning than toothbrushing alone. Therefore, brushing following acid conditioning significantly affects the surfaces of the ormocers.

Analysis of Variance↗
PubMed2005

Discoloration of restorative materials after bleaching application.

OBJECTIVE: The esthetic application of bleaching materials has gained popularity, with consequences for teeth and restorative materials. The aim of this investigation was to evaluate the influence of different bleaching agents with varying peroxide concentrations on restorative materials. METHOD AND MATERIALS: The color behavior, Vickers hardness, and surface roughness were determined on different restorative materials and bovine enamel. Cylindric samples of two fine hybrid composites, one microfilled composite, one compomer, and one ormocer were bleached for two 2-hour periods with three commercial and three experimental bleaching agents with varying peroxide concentrations. The properties were determined before and after bleaching. As a control, all materials were investigated without bleaching after a 14-day storage. RESULTS: The restorative materials showed maximum changes in Vickers hardness of 44, maximum changes in surface roughness of between 0.2 and 0.7 microm, and a maximum discoloration of deltaE = 6.8. A statistically significant deterioration of hardness, combined with the highest discoloration, was found for the microfilled composite and the compomer. Different bleaching systems showed varying effects on surface roughness. CONCLUSION: Bleaching resulted in a deterioration of the restorative materials, indicated by a decrease of hardness and an increase in surface roughness. Generally, bovine enamel showed significantly higher discoloration compared to the restorative materials.

Animals↗