Effects of Particle Abrasion Media and Pressure on Flexural Strength and Bond Strength of Zirconia.

OBJECTIVES: To compare the effects of particle abrasion medium and pressure on shear bond strength and biaxial flexural strength of three generations of zirconia (Lava Frame, Lava Plus, and Lava Esthetic) with the goal of optimizing the bond to zirconia. METHODS: 280 discs (14 mm diameter; 1 mm thickness) of each zirconia were milled and sintered. Specimens of each material were randomly distributed into 14 groups (n=20); half were tested for shear bond strength and half were tested for biaxial flexural strength. The specimens were particle abraded on one surface by 2 different media (50 µm alumina particles or 50 µm glass beads) for 10 seconds at three different pressures (15, 30, and 45 psi or 0.1, 0.2, 0.3 MPa). Untreated specimens served as positive control. A tube (1.50 mm diameter) filled with dual cured resin cement (Panavia SA) was placed onto the surface and light cured. Specimens were stored in water (37°C for 24 hours) and shear bond strength was measured in a universal testing machine (Instron). Biaxial flexural strength of each specimen was measured according to ISO 6872. Shear bond strength and biaxial flexural strength were compared individually with a 2-way analysis of variance (ANOVA) for factors surface treatment and zirconia composition. RESULTS: Significant differences were seen between surface treatments (p<0.01), zirconia composition (p<0.01) and their interaction (p<0.01) for both bond strength and flexural strength. With alumina particle abrasion, higher pressure produced higher bonds for Lava Frame and Lava Plus zirconia while the bond of Lava Esthetic declined with increased pressure. Higher pressure (>0.2 MPa or 30 psi) with alumina decreased biaxial flexural strength with Lava Esthetic zirconia. CONCLUSIONS: Particle abrasion with alumina produced a significantly better combination of bond strength while maintaining biaxial strength of three zirconia materials than particle abrasion with glass beads. The bond strength also depended upon the pressure of particle abrasion and the generation of zirconia used.

Demineralization Inhibition by Two Calcium-releasing Restorative Materials.

OBJECTIVE: To compare the ability of two calcium-releasing restorative materials to inhibit root dentin demineralization in an artificial caries model. METHODS AND MATERIALS: Preparations were made at the cementum-enamel junction of extracted human molars (40, n=10/material) and restored with two calcium-releasing materials (Experimental composite, Pulpdent Corporation and Cention N, Ivoclar Vivadent), a resin composite (Filtek Supreme Ultra, 3M Oral Care), and a resin-modified glass ionomer (RMGI) (Fuji II LC, GC). All materials (other than the RMGI) were used with an adhesive (Scotchbond Universal Adhesive, 3M Oral Care) in the self-etch mode, which was light cured for 10 seconds. All restorative materials were light cured in 2-mm increments for 20 seconds and then finished with a polishing disc. Teeth were incubated (37°C) for 24 hours in water. An acid-resistant varnish was painted onto the teeth around the restoration, leaving a 2-mm border of uncovered tooth. A demineralization solution composed of 0.1 M lactic acid, 3 mM Ca3(PO4)2, 0.1% thymol, and NaOH (to adjust pH=4.5), and a remineralization solution composed of 1.5 mM Ca, 0.9 mM P, and 20 mM Tris(hydroxymethyl)-aminomethane (pH=7.0) were prepared. Specimens were placed in the demineralization solution for 4 hours, followed by the remineralization solution for 20 hours and cycled daily for 30 days. The specimens were embedded, sectioned into 100-µm sections, and the interface between the restorative material and root dentin was viewed with polarized light microscopy. A line was drawn parallel with the zone of demineralization for each tooth. The area of "inhibition" (defined as the area external to the line) or "wall lesion" (defined as the area internal to the line) was measured with image evaluation software. Areas of inhibition were measured as positive values, and areas of wall lesions were measured as negative areas. RESULTS: A one-way analysis of variance (ANOVA) found significant differences between materials for "inhibition/wall lesion" areas in root dentin (p<0.001). Tukey post hoc analysis ranked materials (µm2, mean ±SD): Fuji II LC (5412±2754) > Cention N (2768±1576) and experimental composite (1484±1585) > Filtek Supreme Ultra (-1119±1029). CONCLUSION: The experimental composite and Cention N materials (used with an adhesive) showed net areas of inhibition greater than a reference resin composite, albeit at a lower level than a reference RMGI material (used with no adhesive).

Silver Diamine Fluoride: A Successful Anticarious Solution with Limits.

Silver diamine fluoride (SDF) is a solution containing ionic silver, fluoride, and ammonia that arrests the progress of carious lesions and prevents the development of future caries. The silver particle extends into the dentin tubules and could create some bonding problems for subsequent composite resin restorations placed over SDF-treated darkened tooth structures. The fluoride penetrates deeper into the tooth with SDF as compared with other fluoride solutions, creating a fluoride reservoir in the tooth structure. The fluoride component of SDF contributes to remineralization and fluorapatite formation, producing harder, more caries-resistant tooth structures. The silver provides the antimicrobial activity for the material and inhibits biofilm formation. It has been evaluated in >20 clinical studies and reviewed in systemic reviews. The material was recently approved by the Food and Drug Administration for desensitizing cold-sensitive teeth and has been used off-label to treat carious lesions. SDF will produce a caries lesion darker (brown to black) than the original, which is the major criticism of the material. A nanoparticle-sized silver material was recently developed that may retain the antimicrobial properties of the larger-sized ion silver material without the discoloring effects. The application of SDF is easily adapted for field use. The lesion is isolated, and the solution is painted onto the clean caries lesion and dried. This simple application process requires little equipment, and its low cost per application makes the material ideal for large populations.

Two-year Randomized, Controlled Clinical Trial of a Flowable and Conventional Composite in Class I Restorations.

OBJECTIVES: This study evaluated the two-year clinical performance and volumetric wear of a flowable resin composite compared to a conventional highly filled composite resin in Class I restorations. METHODS AND MATERIALS: In this single-center, single-blinded, comparator-controlled clinical study (Institutional Review Board approved), 120 carious teeth distributed in 60 patients were randomly assigned to four calibrated practitioners who placed occlusal restorations (n=60 flowable and n=60 conventional composite). Direct and indirect assessment at baseline, six months, one year, and two years occurred during which the modified Cvar and Ryge criteria were evaluated. Volumetric wear was determined by superimposition of profilometer scans of baseline and two-year casts. RESULTS: At two years, there was no significant difference in anatomic form (p=0.80), color match (p=0.08), marginal adaptation (p=0.89), marginal discoloration (p=0.79), surface integrity (p=0.18), secondary caries (p=0.66), cold sensitivity (p=0.522), occlusal sensitivity (p=0.818), or volumetric wear (p=0.661) between materials. Both materials showed a decrease in all criteria except secondary caries (p=0.95) over time. Two-year mean volumetric wear was 3.16 ± 2.38 mm(3) for the flowable composite and 3.43 ± 2.50 mm(3) for the conventional composite. CONCLUSIONS: The flowable and conventional composites used in this study have similar clinical efficacy after two years of service when placed as Class I occlusal restorations having isthmus widths less than one-half the intercuspal distance.

Influence of Etching Protocol and Silane Treatment with a Universal Adhesive on Lithium Disilicate Bond Strength.

OBJECTIVES: To measure the effects of hydrofluoric acid (HF) etching and silane prior to the application of a universal adhesive on the bond strength between lithium disilicate and a resin. METHODS AND MATERIALS: Sixty blocks of lithium disilicate (e.max CAD, Ivoclar Vivadent) were sectioned into coupons and polished. Specimens were divided into six groups (n=10) based on surface pretreatments, as follows: 1) no treatment (control); 2) 5% HF etch for 20 seconds (5HF); 3) 9.5% HF etch for 60 seconds (9.5HF); 4) silane with no HF (S); 5) 5% HF for 20 seconds + silane (5HFS); and 6) 9.5% HF for 60 seconds + silane (9.5HFS). All etching was followed by rinsing, and all silane was applied in one coat for 20 seconds and then dried. The universal adhesive (Scotchbond Universal, 3M ESPE) was applied onto the pretreated ceramic surface, air thinned, and light cured for 10 seconds. A 1.5-mm-diameter plastic tube filled with Z100 composite (3M ESPE) was applied over the bonded ceramic surface and light cured for 20 seconds on all four sides. The specimens were thermocycled for 10,000 cycles (5°C-50°C/15 s dwell time). Specimens were loaded until failure using a universal testing machine at a crosshead speed of 1 mm/min. The peak failure load was used to calculate the shear bond strength. Scanning electron microscopy images were taken of representative e.max specimens from each group. RESULTS: A two-way analysis of variance (ANOVA) determined that there were significant differences between HF etching, silane treatment, and the interaction between HF and silane treatment (p<0.01). Silane treatment provided higher shear bond strength regardless of the use or concentration of the HF etchant. Individual one-way ANOVA and Tukey post hoc analyses were performed for each silane group. Shear bond strength values for each etch time were significantly different (p<0.01) and could be divided into significantly different groups based on silane treatment: no silane treatment: 0 HF < 5% HF < 9.5% HF; and RelyX silane treatment: 0 HF < 5% HF and 9.5% HF. CONCLUSIONS: Both HF and silane treatment significantly improved the bond strength between resin and lithium disilicate when used with a universal adhesive.

Enamel wear opposing polished and aged zirconia.

Aging of dental zirconia roughens its surface through low temperature degradation. We hypothesized that age-related roughening of zirconia crowns may cause detrimental wear to the enamel of an opposing tooth. To test our hypothesis, we subjected artificially aged zirconia and reference specimens to simulated mastication in a wear device and measured the wear of an opposing enamel cusp. Additionally, the roughness of the pretest surfaces was measured. The zirconia specimens, artificially aged by autoclave, showed no significant increase in roughness compared to the nonaged specimens. Furthermore, no significant difference in material or opposing enamel wear between the aged and nonaged zirconia was seen. All zirconia specimens showed less material and opposing enamel wear than the enamel to enamel control or veneering porcelain specimens. Scanning electron micrographs showed relatively smooth surfaces of aged and nonaged zirconia following wear testing. The micrographs of the veneering ceramic showed sharp fractured edges and fragments of wear debris. Zirconia may be considered a wear-friendly material for restorations opposing enamel, even after simulated aging.

Clinical evaluation of self-etch and total-etch adhesive systems in noncarious cervical lesions: a two-year report.

OBJECTIVE: The purpose of this study was to compare the clinical performance of two self-etch dental adhesives with Single Bond Plus, a traditional one-bottle total-etch dental adhesive, for the restoration of noncarious cervical lesions. MATERIALS AND METHODS: A total of 156 restorations were placed in noncarious cervical lesions with a minimum depth of 1.5 mm. Patients had no chronic periodontal disease and had normal salivary function. Each patient received restorations on three teeth, each bonded with either Adper Single Bond Plus, Adper Easy Bond, or Adper Scotchbond SE dental adhesive. All lesions were restored with Filtek Supreme Plus composite resin. All teeth were isolated with a rubber dam, received a short enamel bevel, and were cleaned with flour of pumice. The adhesives and resin composite were applied following the manufacturers' instructions. Restorations were clinically evaluated at baseline, six months, one year, and two years using modified US Public Health Service criteria. RESULTS: Two-year retention was recorded as 97.3%, 90.5%, and 95.2%, for Single Bond Plus, Scotchbond SE, and Easy Bond, respectively. Statistical analysis did not show a significant difference (p>0.05) in clinical performance between any of the three adhesives after a period of two years.

Effect of light activation on resin-modified glass ionomer shear bond strength.

OBJECTIVE: Recent studies confirmed that resin-modified glass ionomers (RMGIs) set on the basis of two competing mechanisms, an acid-base reaction and a light-activated resin polymerization. This study evaluated the effect of the setting mechanism on bond strength by measuring the shear bond strength of three RMGIs to dentin with and without light activation. METHODS: Sixty human molars were ground to midcoronal dentin and randomly divided into six even groups: 1) Ketac Nano (KN), 2) KN without light cure (woLC), 3) Fuji Filling LC (FF), 4) FF woLC, 5) Fuji II LC (FII), and 6) FII woLC. The dentin surfaces of the specimens were conditioned/primed according to the manufacturers' instructions. A 1.54-mm diameter plastic tube was filled with RMGI material and affixed to the dentin surface. Groups 1, 3, and 5 were light cured for 20 seconds, and groups 2, 4, and 6 were immediately placed in a damp dark box with no light curing at 37°C for 24 hours. Shear bond strength testing was performed in an Instron device at 1 mm/min. Data were analyzed with a one-way analysis of variance (ANOVA) and Tukey/Kramer test (α=0.05). RESULTS: Mean ± standard deviation shear bond strength values (MPa) are: 7.1 ± 4.2 (KN), 11.7 ± 3.9 (FF), 10.2 ± 3.2 (FF woLC), 12.5 ± 5.1 (FII), and 0.3 ± 0.4 (FII woLC). Two KN, all KN woLC, and seven FII woLC specimens debonded before testing. Tukey/Kramer analysis revealed no significant differences in bond strength between the three light-cured RMGIs. KN and FII showed significantly lower bond strength without light cure, but no significant difference was observed between FF and FF woLC. CONCLUSIONS: The results of this study strongly suggest that light activation is necessary to obtain optimal bond strength between RMGI and dentin. FF may contain components that chemically activate resin polymerization. Clinically, KN and FII need to be light cured after placement of these RMGIs.

Evaluation of outgassing, tear strength, and detail reproduction in alginate substitute materials.

OBJECTIVE: To compare three alginate substitute materials to an alginate impression material for cast surface porosity (outgassing), tear strength, and detail reproduction. MATERIALS AND METHODS: Detail reproduction tests were performed following American National Standards Institute/American Dental Association (ANSI/ADA) Specification No. 19. To measure tear strength, 12 samples of each material were made using a split mold, placed in a water bath until testing, and loaded in tension until failure at a rate of 500 mm/min using a universal testing machine. For cast surface porosity testing, five impressions of a Teflon mold with each material were placed in a water bath (37.8°C) for the in-mouth setting time and poured with vacuum-mixed Silky Rock die stone at 5, 10, 30, and 60 minutes from the start of mixing. The gypsum samples were analyzed with a digital microscope for surface porosity indicative of hydrogen gas release by comparing the surface obtained at each interval with four casts representing no, little, some, and significant porosity. Data analysis was performed using parametric and Kruskal-Wallis analysis of variance (ANOVA), Tukey/Kramer post-hoc tests (α=0.05), and individual Mann-Whitney U tests (α=0.0167). RESULTS: All alginate substitute materials passed the detail reproduction test. Tear strength of the alginate substitute materials was significantly better than alginate and formed three statistically different groups: AlgiNot had the lowest tear strength, Algin-X Ultra had the highest tear strength, and Position Penta Quick had intermediate tear strength. Significant variation in outgassing existed between materials and pouring times (p<0.05). All alginate substitute materials exhibited the least outgassing and cast porosity 60 minutes after mixing. CONCLUSIONS: Detail reproduction and tear strength of alginate substitute materials were superior to traditional alginate. The outgassing effect was minimal for most materials tested. Alginate substitute materials are superior replacements for irreversible hydrocolloid.

Posterior resin-based composite: review of the literature.

The use of direct posterior resin-based composite has increased primarily due to patient esthetic desires and product improvements. Other factors (substantiated or not) contributing to increased use of resin-based composite are environmental and health concerns with dental amalgam. New visible light cured resin-based composite products are introduced yearly, as manufacturers continue to improve this tooth-colored restorative material. This paper will characterize current posterior resin-based composite materials (hybrid, microfill, flowable, and packable), review recent in vitro and clinical research, and recommend indications for these materials. In addition, the literature on compomers will be reviewed and recommendation made for their use. The data indicates that composite resin is a technique sensitive restorative material that can be used in large preparations if proper manipulation and isolation can be maintained. Compomers may also be used as an esthetic posterior restorative if proper isolation is provided.

The performance of bonded vs. pin-retained complex amalgam restorations: a five-year clinical evaluation.

BACKGROUND: The authors compared the clinical performance of complex amalgam restorations, replacing at least one cusp--retained either mechanically with self-threading pins or bonded--with a filled, 4-methacryloxyethyl trimellitate anhydride, or 4-META-based resin designed for amalgam bonding. METHODS: The authors placed 60 amalgam restorations (28 pin-retained and 32 bonded), each restoration replacing at least one cusp. They used self-threading stainless steel pins in the pin-retained group and a filled, 4-META-based bonding resin in the bonded group. For both groups, the authors left in place any retention form remaining after removal of an old restoration but did not enhance it. RESULTS: At four years, six restorations had failed. At five years, of the 40 restorations available for evaluation, three had failed, for a total of nine failed restorations; seven of those were pin-retained and two were bonded. Using the Fisher exact test to compare the groups at five years, the authors found no significant difference in failure rate, marginal adaptation, marginal discoloration, secondary caries, tooth sensitivity or tooth vitality. CONCLUSIONS: At five years, there was no difference in the performance of pin-retained amalgam restorations and bonded amalgam restorations. This study will be continued for at least a sixth year. CLINICAL IMPLICATIONS: Bonding with a filled, 4-META-based bonding resin appears to be a satisfactory method of retaining large amalgam restorations replacing cusps.

Selected mechanical properties of fluoride-releasing restorative materials.

Mechanical properties, diametral tensile strength (DTS) and flexural strength (FS) of six fluoride releasing materials were measured and compared. The samples were prepared and tested according to ISO specifications. The materials included a glass ionomer (Fuji IX), a resin-modified glass ionomer (Photac-Fil), two compomers (F 2000; Dyract AP) and two composites (Solitaire; Tetric Ceram). The tests were performed after the materials were stored in distilled water (DTS) and phosphate buffered saline solution (FS) at 37 degrees C for 24 hours and one week. Fluoride-releasing composite resin had the highest flexural and diametral tensile strengths and were statistically stronger than compomers, followed by resin-modified glass ionomer and conventional glass ionomer. However, a notable exception to this general trend was Solitaire, a fluoride-releasing composite resin.

Shear bond strength of four filled dentin bonding systems.

This study compared the shear bond strength of four filled dentin bonding agents (Prime & Bond NT, One Coat Bond, OptiBond Solo, PermaQuik1) to a conventional unfilled Dentin Bonding agent (3M Scotchbond Multipurpose Plus). A column of composite resin (Herculite XRV Restorative Resin) was bonded to human dentin using the five dentin-bonding systems following the manufacturers' directions. The specimens were thermocycled 1000 cycles from 6 to 60 degrees C. Each specimen was tested on an MTS machine in shear-to-failure. The data were subjected to One-Factor ANOVA and Newman-Kuels post-hoc tests. Statistical analysis revealed that One Coat Bond had significantly greater shear bond strength than all other materials tested.

Effect of delayed application on shear bond strength of four fifth-generation bonding systems.

This study compared the shear bond strength of four adhesives dispensed 10 minutes prior to use to immediate dispensing and use. For half (40) of the specimens (n = 10), four different dentin bonding agents (One Coat, Bisco One Step, Prime & Bond 2.1 and 3M Single Bond) were used to bond a column of composite resin (Z100 Restorative Resin) to the dentin surface following manufacturers' directions and using the dentin bonding agent immediately after dispensing. For the remaining specimens, the same procedure was followed except that the dentin-bonding agent was dispensed 10 minutes prior to use. All specimens were tested two weeks after bonding on a MTS machine. The data obtained was subjected to Two-factor ANOVA and Tukey-B post-hoc tests. The statistical analysis showed that there was no significant difference between the control groups and the experimental groups, although the dentin bonding agents containing acetone showed a trend toward lower bond strengths when not used immediately after dispensing.

Microleakage and adaptation of Class II packable resin-based composites using incremental or bulk filling techniques.

PURPOSE: To compare the ability of three packable resin-based composite (RBC) systems (ALERT, SureFil, and Solitaire), placed and light-cured in either incremental layers or in bulk, to seal the gingival margin of Class II preparations when the gingival margin is placed apical to the cementoenamel junction. MATERIALS AND METHODS: Packable RBCs were used to restore 60 extracted human premolars with Class II preparations using an incremental-cure technique (each layer no greater than 2 mm in thickness when light-cured) or a bulk-cure technique (n=10). Manufacturers' directions were followed; the cure technique was the only variable. After the restorations were completed, the specimens were thermocycled, stained, sectioned, and viewed under a light microscope for microleakage at the gingival margin. RESULTS: All specimens showed leakage at the gingival margin. No statistically significant difference was found between the bulk-cure and incremental-cure techniques for each of the RBC systems evaluated. ALERT had significantly less leakage than SureFil and Solitaire.

Shear bond strength to moist and dry dentin of four dentin bonding systems.

PURPOSE: To compare the shear bond strength of four single-bottle adhesive systems (Prime & Bond NT, Single Bond, Gluma Comfort Bond, Gluma Comfort Bond + Desensitizer) bonded to moist and dry dentin. MATERIALS AND METHODS: A column of resin-based composite was bonded to human dentin using the dentin bonding systems following manufacturers' directions (n= 12). For half the specimens, the dentin was dried completely after acid etching (air dried for 10 s). For the remaining specimens, the dentin was left moist (glistening appearance with no puddles) after acid etching. All specimens were thermocycled for 1,000 cycles at 6-60 degrees C, placed in a fixture on an MTS machine and loaded in shear until failure. RESULTS: Statistical analysis revealed that dentin condition (moist or dry) was significant for Prime & Bond NT, Single Bond, and Gluma Comfort Bond. Bonding to moist dentin produced higher bond strengths than bonding to dry dentin. For Gluma Comfort Bond + Desensitizer, no statistical difference was found between bonding to moist vs. dry dentin. Over all, Single Bond and Gluma Comfort Bond bonded to moist dentin produced significantly higher bond strengths than all other groups.

Color stability of fluoride-containing restorative materials.

Six fluoride-releasing materials of shade A3 were tested: one glass ionomer (Fuji IX), one resin-modified glass ionomer (Photac-Fil), two compomers (F 2000 and Dyract AP) and two composites (Tetric Ceram and Solitaire). Disk-shaped specimens of each material were prepared according to manufacturer's instructions, polished and L*a*b* baseline measurements taken. Specimens were randomly divided into two groups and given four different treatments of UV light exposure and immersion in a staining solution. Chromo Meter color measurements were taken following each treatment. Two-way ANOVA and Duncan Multiple Range post-hoc tests were used to compare color changes as a function of the four treatment conditions and one-way ANOVA was used to compare materials for each treatment separately. The results showed significant difference in shade A3 between products. In general, the hydrophobic materials showed greater color stability and stain resistance than the hydrophilic materials. Tetric ceram had the best color stability and stain resistance, while Fuji IX had the least.

An evaluation of four light-curing units comparing soft and hard curing.

Composite resin shrinks during polymerization producing marginal gaps around composite restorations. While incremental placement of composite resin has been used to control shrinkage, this technique is time consuming. Curing lights have been developed with varying outputs and curing cycles to speed curing and reduce marginal gaps in composite restorations. This investigation measured the marginal openings of Class V resin restorations cured with four different light-curing units. High-intensity curing units provided rapid curing to composite resin increments, but the two-phase curing cycle afforded significantly better marginal integrity than the other units.

Fracture resistance of complex amalgam restorations.

This study evaluated fracture resistance provided to complex amalgam restorations by adhesive and mechanical resistance features. The occlusal surfaces of 30 extracted molar teeth of similar size were ground flat to approximately 2 mm coronal to the CEJ. The teeth were divided into three groups. Roots were notched and embedded in acrylic resin. In two groups, four TMS Minim stainless steel pins were placed into dentin at the line angles. A copper band matrix was applied to each specimen and reinforced with compound. After applying either Copalite or Amalgambond Plus, Tytin amalgam was condensed into the matrix. The bands and excess amalgam were removed 10 minutes later, and each amalgam occlusal surface was ground flat to give the amalgam restoration a 4 mm occlusal height. Specimens were thermocycled for 2500 cycles at 6-60 degrees C with a 30-second dwell time. They were then stored in deionized water for 1 month at room temperature. A 1 mm 45 degrees bevel was placed on the facio-occlusal angle of the amalgam. Each specimen was loaded to failure in compression at 45 degrees in an Instron Testing Machine at a crosshead speed of 5 mm/min. The groups were: Group 1, four Minim pins and Copalite; Group 2, four Minim pins and Amalgambond Plus; and Group 3, Amalgambond Plus only. The data were analyzed using a one-factor ANOVA and a Tukey B post hoc test. There was no significant difference between Groups 1 and 3. The Amalgambond Plus combined with pins provided significantly greater resistance to fracture than pins or Amalgambond Plus alone (P < 0.05).

Accelerated aging affects color stability of provisional restorative materials.

PURPOSE: The color stability of two shades each of five acrylic resin and seven resin composite provisional restorative materials was evaluated by reflection spectrophotometry following in vitro accelerated aging. MATERIALS AND METHODS: Specimens of provisional restorative materials were polymerized according to manufacturers' instructions and aged in an artificial aging chamber with exposure to a total ultraviolet irradiation of 60 kJ/m2. Color was measured by CIE L*a*b* on a reflection spectrophotometer before and after aging. Color change (delta E*) was calculated and analyzed statistically. RESULTS: Statistically significant changes in color were observed after accelerated aging. Nine of the 12 provisional materials tested showed perceptible color change of at least one of the shades tested. The most color-stable materials were the acrylic, Alike, and the resin composites, Luxatemp and Protemp Garant, which had no perceptible color changes under these conditions. CONCLUSIONS: Some acrylic resin and composite provisional materials change color significantly and perceptibly when exposed to in vitro accelerated aging conditions.