Protective effect of a nanofilled resin-based coating on wear resistance of glass ionomer cement restorative materials.

BACKGROUND: The effect of nanofilled resin-based coating on the wear resistance of glass ionomer cements (GICs) is still controversial. This study aims to compare the wear resistance of four encapsulated GICs including two conventional and two resin-modified, and to evaluate the effect of G-Coat Plus on the wear resistance of GICs. METHODS: A total of 80 disk-shaped specimens were prepared from two CGICs (riva self cure (SDI) and Equia Forte Fil (GC) and two RM- GICs (Ketac Nano (3 M/ESPE) and Fuji II LC (GC). The specimens of each material were divided into two groups (n = 10) based on the surface protection: no coating (NC), and coating with G-Coat Plus (GCP). All specimens were then placed in distilled water for 24 h at 37 °C. The specimens were subjected to thermocycling for 120,000 cycles using a chewing simulator. Wear resistance was measured using a specific formula. Data was analyzed using Kruskal-Wallis test. RESULTS: There was no significant difference in volume loss (mm3) between coated and uncoated groups for all materials (P > 0.05). Ketac Nano showed significantly lower volume loss (0.65 ± 0.12) compared to all other groups (P < 0.05) among uncoated specimen, and significantly lower than Fuji II LC (P = 0.035) and Equia Forte Fil (P = 0.040) among coated groups. However, no statically significant difference was observed between volume loss of coated Ketac Nano with that of riva self cure (P = 0.087). CONCLUSIONS: Coating with GCP did not affect the wear depth of GICs, and Ketac Nano showed significantly lower volume loss regardless of coating.

Physical and Mechanical Properties of Bulk-Fill, Conventional, and Flowable Resin Composites Stored Dry and Wet.

Surface degradation, margin, and bulk fracture are common reasons that necessitate replacement of resin composite restorations. The purpose of this study was to determine filler weight (FW), fracture toughness (FT), Vickers hardness (VHN), sorption/solubility (S/S), and colour change (ΔE) of four resin composites in dry and wet conditions. Four resin composites of shade A2 were investigated: Aura bulk-fill (AB) (SDI), Tetric Evoceram (TE) (Ivoclar), G-ænial Universal Flo (GUF) (GC), and GC Kalore (GCK) (GC). For FT, VHN, and ΔE, the specimens were prepared, divided into 2 groups, and stored dry or immersed in distilled water. The specimens were subdivided into three subgroups and stored for 1, 7, and 60 days and then subjected to the relevant tests. Six fractured remnants were weighed for each material to measure FW%. To test S/S, ISO 4049 was used. The data were analysed using ANOVA and Tukey's test. There was an inverse correlation between FW and FT. A significantly higher FT was found for GUF. There were no significant differences between conditions in materials except for AB. The highest VHN was found for GCK and AB. After 1 and 7 days, a significant difference was observed in S/S between all materials with the highest values for GUF. There was a correlation between sorption and solubility. The material, the media, and aging have an influence on the properties of resin composites. It is important to emphasise that each material should be used for a specific clinical need based on their properties.

Microtensile bond strength of glass ionomer cements to a resin composite using universal bonding agents with and without acid etching.

OBJECTIVES: To assess the effect of two universal bonding agents on the microtensile bond strength (µTBS) of encapsulated conventional glass ionomers (CGICs) and resin-modified glass ionomers (RMGICs) to a resin composite, with or without the use of 35% phosphoric acid. METHODS: Four materials were used in this study: Riva Self-cure and Riva Light-cure; SDI and Equia Forte Fil and Fuji II LC; GC. The specimens were prepared in Teflon moulds with half the specimens for each GIC etched using 35% phosphoric acid (Ultra-Etch) and the remainder not etched. Each group was randomly subdivided into three groups, where the first two groups received an air-thin layer of bonding agent (G-Premio Bond = GPB or Clearfil Universal Bond = CUB) then light cured; and the third group had no bonding agent. For all groups, a nanohybrid composite (GC Kalore; GC) was placed incrementally on the GIC. Following 24 h immersion in distilled water, each block was embedded in epoxy resin in a cubic mould and sectioned by a cutting device. The stick specimens were then subjected to µTBS testing. RESULTS: The application of both universal bonding agents significantly enhanced the µTBS of all GICs (p < 0.001). Both RMGICs exhibited higher µTBS compared to that of CGICs (p < 0.001). The application of universal bonding agents with acid etching significantly increased the µTBS of both CGICs and RMGICs to resin composite in contrast to without acid etching. CONCLUSION: Using 35% phosphoric acid for 15 s prior to the application of universal bonding agents improved the µTBS of GIC to resin composite. CLINICAL SIGNIFICANCE: Using Universal bonding agents with 15 s acid etching may increase the bond strength of both CGICs and RMGICs to resin composite when utilising the sandwich technique.

Mathematical validation of measurement of root fracture resistance: an in vitro study.

BACKGROUND: The aim of this study was to develop a mathematically valid method of assessing fracture resistance of roots. The model developed used mesial roots of lower molars instrumented using stainless steel hand files (SS) and two rotary nickel-titanium (NiTi) systems. METHODS: Eighty human lower molars were selected and randomly divided into four groups (n = 20). After instrumentation, the root canals were obturated using thermoplasticized gutta percha. The roots were covered with a simulated periodontal ligament and mounted vertically in autopolymerizing acrylic in PVC tubes. Using a universal testing machine, the force to fracture (N) was applied and the maximum load (FL) was recorded. Remaining dentine volume was calculated and the fracture resistance (FR) was recorded. The data were analyzed using SPSS version 22 with P < .05. RESULTS: There were no significant differences among the instrumentation methods for FL but in FR the roots instrumented using rotary NiTi showed significantly lower values than control groups and SS files (P < 0.001). CONCLUSIONS: Considering the effect of root length, volume of the root, and volume of the instrumented canal as well as the maximum failure load may be a more objective method of reporting fracture resistance of roots.

The effect of sodium hypochlorite enamel pretreatment on the shear bond strength of fissure sealant using a resin-modified glass ionomer cement and a fluoride-releasing self-etch resin adhesive.

BACKGROUND: The relative high caries risk of pits and fissures highlights the importance of protecting these areas. The aim is to determine the effect of sodium hypochlorite (NaOCl) on the shear bond strength (SBS) of resin-based pit and fissure sealant (RBPFS) material to enamel using resin-modified glass ionomer cement (RMGIC) and fluoride-releasing self-etch resin (FRSE) adhesives. MATERIALS AND METHODS: In this in vitro study extracted third molar teeth without carious lesions or defects were divided into five experimental groups (n = 20). Group A: (Control group) etch (35% phosphoric acid) for 15 s and RBPFS applied. Group B: Etch for 15 s, FRSE and RBPFS applied. Group C: Pretreated with 5% NaOCl and similar steps to Group B. Group D: Etch for 15 s then RMGIC bonding agent and RBPFS applied. Group E: Pretreated with 5% NaOCl and then similar steps to Group D. SBS was determined using a universal testing machine. The tested specimens were examined under a field-emission scanning electron microscope. Data were analyzed using one-way ANOVA and post hoc Tukey's tests (P=0.05). RESULTS: A statistically significant difference between the test groups was observed; Group C showed the highest SBS mean value (7.52 ± 2.74 MPa) and Group D showed the lowest (4.48 ± 1.81 MPa) (P < 0.001). Pretreatment with NaOCl increased the SBS of fissure sealant when Riva bond LC was used (P = 0.049). CONCLUSION: The use of NaOCl as pretreatment can increase the SBS of RBPFS to enamel using RMGIC adhesive. FRSE adhesive did not show improvement in SBS values using pretreatment.

The Effect of Nanofilled Resin-Base Coating on the Mechanical and Physical Properties of Resin Composites.

OBJECTIVE: The aim of this study was to evaluate the effects of a nanofilled resin-base coating on the physical and mechanical properties of four different types of resin composites. MATERIALS AND METHODS: Disc-shaped specimens of four resin composites (Aura bulk fil [SDI], IPS Impress Direct [Ivoclar], Filtek Z250, and Filtek P60 [3M/ESPE]) were prepared and divided in two groups: either uncoated or coated with G-coat plus (n = 10). The specimens were obtained and stored in distilled water (DW) at 37°C. For water sorption and solubility, the specimens were stored for 60 days in DW and measured according to ISO 4049 instructions. The specimens were subjected to color change (ΔE), microhardness, and flexural strength (FS) measurements after 24 hours and 60 days of immersion in DW. STATISTICAL ANALYSIS: ANOVA, post hoc Tukey's, and independent t-tests were used to analyze data. RESULTS: Mean solubility values of coated groups were significantly lower than that of uncoated ones (p < 0.001). No significant differences were detected between neither water sorption nor FS of coated and uncoated groups (p = 0.502 and p = 0.510, respectively). For all materials except IPS Empress, the mean values for ΔE were not statistically different between coated and uncoated groups, and mean microhardness values of the uncoated groups were significantly greater than the coated groups (p < 0.001). CONCLUSION: Coating resin composites improved water sorption and solubility but increased ΔE, decreased microhardness, and had no significant effect on FS in the long run.

The effects of nanofilled resin-based coatings on the physical properties of glass ionomer cement restorative materials.

OBJECTIVES: To determine the effect of two resin-based coatings on the water sorption/solubility and colour change of three conventional and two resin modified glass ionomer cement restorative materials. METHODS: Five glass-ionomer cement (GIC) restorative materials and two nanofilled resin-based coatings were studied. Disc-shaped specimens of each material were prepared and divided into three groups, uncoated and coated with either of the two coatings tested (n = 8). Water sorption and solubility were measured in accordance with ISO 4049 and ISO 6876 instructions, respectively. For colour change, the specimens were immersed in distilled water for 24 h, then immersed for another 24 h and an extra week in the three solutions of lactic acid, coffee, and distilled water. The specimens were subjected to colour measurements, using a spectrophotometer after 24 h and 7 days of immersion. The colour change (ΔE) was calculated using a specific formula. ANOVA tests were used for data analysis. RESULTS: Two-Way ANOVA revealed a significant interaction between materials and coatings for the water sorption/solubility values. Fuji Bulk showed the lowest water sorption/solubility and the coated groups showed a lower mean sorption/solubility and ΔE. The ΔE varied depending on the materials and the solutions. CONCLUSIONS: Coating of GIC restoratives reduced the water sorption/solubility and ΔE of almost all materials with a significant decline in most of the materials. CLINICAL SIGNIFICANCE: Coating of GIC restorations in the oral environment with resin-based coating may protect the restorations from early water sorption/solubility and discolouration.

Influence of beverages and surface roughness on the color change of resin composites.

AIM: The aim of the present study was to determine the degree of surface staining and roughness of resin composites (RC) after finishing and polishing with different methods and immersion in three soft drinks. METHODS: A microhybrid, a nanohybrid, and a hybrid composite were selected. The specimens were prepared and divided into three groups of 36 after 24 hours, and designated as either unpolished or polished using Sof-Lex discs or Enhance point. Each group was further divided into three subgroups, immersed in distilled water, coffee, or cola for 1 week (N = 12). Color change (∆E) was measured by a spectrophotometer after each treatment. The ∆E was calculated using the following formula: ∆E = ([∆L]2+[∆a]2+[∆b]2)1/2. Surface roughness (Ra) was measured after 24 hours and 1 week. To observe the Ra, a scanning electron microscope was used. RESULTS: A moderate correlation between Ra and ∆E was determined. Only coffee caused perceptible ∆E. The effect of Ra on staining was statistically significant (P < .05), but immersion in solutions for 7 days did not increase the Ra of RC. CONCLUSIONS: The highest Ra values were obtained from hybrid RC. The Enhance point created the greatest roughness. Coffee was associated with the greatest ∆E for all materials and polishing methods.

Influence of Curing Mode on the Surface Energy and Sorption/Solubility of Dental Self-Adhesive Resin Cements.

This study investigated the influence of curing mode (dual- or self-cure) on the surface energy and sorption/solubility of four self-adhesive resin cements (SARCs) and one conventional resin cement. The degree of conversion (DC) and surface energy parameters including degree of hydrophilicity (DH) were determined using Fourier transform infrared spectroscopy and contact angle measurements, respectively (n = 5). Sorption and solubility were assessed by mass gain or loss after storage in distilled water or lactic acid for 60 days (n = 5). A linear regression model was used to correlate between the results (%DC vs. DH and %DC/DH vs. sorption/solubility). For all materials, the dual-curing consistently produced significantly higher %DC values than the self-curing (p < 0.05). Significant negative linear regressions were established between the %DC and DH in both curing modes (p < 0.05). Overall, the SARCs showed higher sorption/solubility values, in particular when immersed in lactic acid, than the conventional resin cement. Linear regression revealed that %DC and DH were negatively and positively correlated with the sorption/solubility values, respectively. Dual-curing of SARCs seems to lower the sorption and/or solubility in comparison with self-curing by increased %DC and occasionally decreased hydrophilicity.

Impact of bleaching agents on water sorption and solubility of resin luting cements.

AIM: The aim of the present study was to evaluate the effect of distilled water and home and office bleaching agents on the sorption and solubility of resin luting cements. METHODS: A total of 18 disc-shaped specimens were prepared from each of four resin cements: G-CEM LinkAce, Panavia F, Rely X Unicem, and seT. Specimens were cured according to the manufacturers' instructions and randomly divided into three groups of six, where they were treated with either an office or home bleaching agent or immersed in distilled water (control). Water sorption and solubility were measured by weighing the specimens before and after immersion and desiccation. Data were analyzed using Pearson correlation coefficient, two-way analysis of variance (ANOVA) and Tukey's test. RESULTS: There was a significant, positive correlation between sorption and solubility. Two-way anova showed significant differences among all resin cements tested for either sorption or solubility. Water sorption and solubility of all cements were affected significantly by office bleaching, and even more by home bleaching agents. CONCLUSIONS: Sorption and solubility behavior of the studied cements were highly correlated and significantly affected by applying either office or home bleaching agents; seT showed the highest sorption and solubility, whereas Rely X Unicem revealed the lowest.

Fracture toughness of seven resin composites evaluated by three methods of mode I fracture toughness (KIc).

This study compared the fracture toughness values of seven resin composites and analyzed the consistency of data values using three methods: compact tension, three point and four point bending for Mode I failure. Seven resin composites were selected: Estellite Sigma Quick, Esthet X HD, Filtek Supreme XTE, Heliomolar, Ice, Rok, and Vit-l-escence. For each material, 18 specimens (n=6 for each test) were prepared. Maximum load to failure was recorded using a universal testing machine and fracture toughness was calculated. There was a direct significant correlation among all tested methods. Rok showed the highest and Estelite the lowest KIc values. SEM of the fractured surface of compact tension method showed propagation of the cracks from stresses concentrating at the corner of the notch and the surface of the sample. Four-point test gave the largest range in KIc and was a simple method to discriminate between the resin composite values of KIc.

The Comparison of Sorption and Solubility Behavior of Four Different Resin Luting Cements in Different Storage Media.

STATEMENT OF THE PROBLEM: Structural integrity and dimensional stability are the key factors that determine the clinical success and durability of luting cements in the oral cavity. Sorption and solubility of self-adhesive resin luting cements in food-simulating solutions has not been studied sufficiently. PURPOSE: This study aimed to compare the sorption and solubility of 2 conventional and 2 self-adhesive resin-based luting cements immersed in four different storage media. MATERIALS AND METHOD: A total of 32 disc-shaped specimens were prepared from each of four resin luting cements; seT (SDI), Panavia F (Kuraray), Clearfil SA Cement (Kuraray), and Choice 2 (Bisco). Eight specimens of each material were immersed in all tested solutions including n-heptane 97%, distilled water, apple juice, or Listerine mouth wash. Sorption and solubility were measured by weighing the specimens before and after immersion and desiccation. Data were analyzed by SPSS version 18, using two-way ANOVA and Tukey's HSD test with p≤ 0.05 set as the level of significance. RESULTS: There was a statistically significant interaction between the materials and solutions. The effect of media on the sorption and solubility was material-dependent. While seT showed the highest values of the sorption in almost all solutions, Choice 2 showed the least values of sorption and solubility. Immersion in apple juice caused more sorption than other solutions (p≤ 0.05). CONCLUSION: The sorption and solubility behavior of the studied cements were significantly affected by their composition and the storage media. The more hydrophobic materials with higher filler content like Choice 2 resin cement showed the least sorption and solubility. Due to their lower sorption and solubility, these types of resin-based luting cements are recommended to be used clinically.

Comparison of the Mechanical Properties of Early Leukocyte- and Platelet-Rich Fibrin versus PRGF/Endoret Membranes.

Objectives. The mechanical properties of membranes are important factors in the success of treatment and clinical handling. The goal of this study was to compare the mechanical properties of early leukocyte- and platelet-rich fibrin (L-PRF) versus PRGF/Endoret membrane. Materials and Methods. In this experimental study, membranes were obtained from 10 healthy male volunteers. After obtaining 20 cc venous blood from each volunteer, 10 cc was used to prepare early L-PRF (group 1) and the rest was used to get a membrane by PRGF-Endoret system (group 2). Tensile loads were applied to specimens using universal testing machine. Tensile strength, stiffness, and toughness of the two groups of membranes were calculated and compared by paired t-test. Results. The mean tensile strength and toughness were higher in group 1 with a significant difference (P < 0.05). The mean stiffness in group 1 was also higher but not statistically significant (P > 0.05). Conclusions. The results showed that early L-PRF membranes had stronger mechanical properties than membranes produced by PRGF-Endoret system. Early L-PRF membranes might have easier clinical handling and could be a more proper scaffold in periodontal regenerative procedures. The real results of the current L-PRF should be in fact much higher than what is reported here.

Characterization of the bioactive and mechanical behavior of dental ceramic/sol-gel derived bioactive glass mixtures.

Dental ceramics can be modified by bioactive glasses in order to develop apatite layer on their surface. One of the benefits of such modification is to prolong the lifetime of the fixed dental prosthesis by preventing the formation of secondary caries. Dental ceramic/sol-gel derived bioactive glass mixture is one of the options for this modification. In the current study, mixtures of dental ceramic/bioactive glass with different compositions were successfully produced. To evaluate their bioactive behavior, prepared samples were immersed in a simulated body fluid at various time intervals. The prepared and soaked specimens were characterized using Fourier transform infrared spectroscopy, X-ray diffractometry and scanning electron microscopy. Since bioactive glasses have deleterious effects on the mechanical properties of dental ceramics, 3-point bending tests were used to evaluate the flexural strength, flexural strain, tangent modulus of elasticity and Weibull modulus of the specimens in order to find the optimal relationship between mechanical and bioactive properties.

Effect of calcium chloride on physical properties of calcium-enriched mixture cement.

The aim of this study was to evaluate the effect of adding 10% calcium chloride (CaCl2) on the setting time, solubility and the pH of calcium-enriched mixture (CEM) cement. Setting time was assessed in accordance with American Dental Association specification N°57. Solubility was measured at 24 and 72 h, 7 and 14 days in hydrated and dehydrated conditions by calculating weight change. The pH of MiliQ water in which the CEM cement samples were immersed was measured immediately after each time interval with and without the addition of CaCl2. The data were analysed using the Mann-Whitney U-test and the Student's t-test. The initial setting time was significantly decreased after the addition of 10% CaCl2. The pH of water increased immediately when in contact with the cements in both groups. The weight loss of hydrated and dehydrated specimens was more than 3% and was significantly reduced by the addition of 10% CaCl2.

Effect of home bleaching on the mechanical properties of resin luting cements using Hertzian indentation test.

AIM: The aim of the present study was to determine the effects of immersion time and 10% carbamide peroxide treatment using a Hertzian indentation test after placing resin-based cements into 37°C distilled water, with and without 10% carbamide peroxide. METHODS: Disc-shaped specimens (10-mm diameter × 1-mm thick), were prepared from five resin-based cements; seT PP, Maxcem Elite, RelyX Unicem, Panavia F, and G-Cem. The specimens of each material were randomly divided into three groups of six. The study groups were bleached with 10% carbamide peroxide on one surface for 21 days for 2 h per day. Two control groups were kept in distilled water for either 24 h or 21 days. A load was applied to the center of the disc using a hard, steel ball. The load at the first crack was recorded. RESULTS: Significant differences were observed between the cements. seT PP showed the highest strength, and G-Cem the lowest. Differences between the treatment and control groups were statistically significant for all cements, except Panavia F. CONCLUSIONS: The effect of 10% carbamide peroxide treatment reduces cement strength, which could be important for patients undergoing bleaching who have crowns.

Cure mechanisms in materials for use in esthetic dentistry.

The current paper reviews the curing mechanisms found in resin-based materials used in dentistry. Historical aspects of dental products and the associated curing mechanisms are reviewed. In comparison with common industrial procedures, curing methods employed for dental materials are relatively limited because of the need to polymerize quickly in the oral cavity at an ambient temperature. Heat-cure and self-cure dental resins utilize benzoyl peroxide initiator alone with a tertiary amine co-initiator. At present, most dental restorative composites use a camphorquinone-amine complex initiation, visible light-cure, one-component systems, although alternative photoinitiators have been researched and developed. A multiple curing mode in a dual-cure material is a complex combination of various initiation systems. The use of aryl sulfinic acid sodium salt to overcome adverse chemical interactions between simplified adhesives and self- or dual-cure composites is based on another self-cure polymerization mechanism, sulfinic acid-initiated polymerization, proposed by Hagger in 1948. The sodium salt of aryl sulfinic acid reacts with an acidic monomer in simplified adhesives, and is believed to produce radicals. Clinically, it is important to try to optimize the degree of conversion of resin-based materials using proper manipulation and adequate light-curing techniques to ensure the best outcome for materials used to restore teeth.

The effect of aging on the fracture toughness of esthetic restorative materials.

PURPOSE: To compare the fracture toughness (KIc) of tooth-colored restorative materials based on a four-point bending; to assess the effect of distilled water and a resin surface sealant (G-Coat Plus) on the resistance of the materials to fracture. METHODS: Specimens were prepared from six materials: Quix Fil; Dyract (Dentsply), Freedom (SDI), Fuji VII (GC), Fuji IX (GC); Fuji II LC (GC). Fuji II LC and Fuji IX were tested both with and without applying G-Coat Plus (GC). The specimens were divided into the three groups which were conditioned in distilled water at 37 degrees C for 48 hours, 4 and 8 weeks. The specimens were loaded in a four-point bending test using a universal testing machine. The maximum load to specimen failure was recorded and the fracture toughness calculated. RESULTS: There were significant differences among most of the materials (P < 0.001). Quix Fil had the highest mean KIc value and Fuji VII the lowest. Immersion in distilled water for the resin composite and polyacid-modified resin composites caused a significant decrease in KIc as the time interval increased. For glass-ionomer cements, KIc decreased significantly after 4 weeks, and after 8 weeks immersion slightly increased. G-Coat Plus affected Fuji II LC positively while it had no effect on the Fuji IX.

Comparison of the effect of storage media on shear punch strength of resin luting cements.

OBJECTIVES: To measure the shear punch strength of eight resin-containing luting cements before and after immersion in acidic solution and ethanol at different temperatures (37 degrees C and 60 degrees C). METHOD: Specimens were prepared from six resin luting cements; Set (SDI), Panavia F (Kuraray), RelyX Veneer (3M/ESPE), VarioloinkII (Ivoclar), Maxcem (Kerr), Nexus2 (Kerr) and two Resin-modified glass-ionomer luting cements (RM-GICs); GC Fuji Plus (GC Corporation), RelyX Luting 2 (3M/ESPE). For each material a total of 114 disc-shaped specimens were prepared. Six specimens were immersed in distilled water for 24 h at 37 degrees C, polished and subjected to baseline measurement for shear punch strength. The remaining 108 specimens were randomly divided into 18 groups of six, and immersed in three solutions; distilled water, 0.01 mol/L lactic acid, and 50% ethanol at 37 degrees C or 60 degrees C, for 1 week, 1 month or 3 months. Specimens were washed, dried and tested for final shear punch strength. RESULTS: Values were material and solution dependent. Values of Nexus 2 and Rely X Veneer are the highest, and Rely X Luting 2 the lowest. Ethanol and lactic acid specimens showed significantly lower values compared with the distilled water specimens. CONCLUSION: The shear punch strengths of the resin-containing luting cements were affected by time and storage solution. While some of the resin luting cements had significantly higher values compared to that of the RM-GICs, there were no significant differences between the RM-GICs and resin cements such as Panavia F and Set.

Comparison of the effect of storage media on hardness and shear punch strength of tooth-colored restorative materials.

PURPOSE: To measure the surface hardness and shear punch strength of six tooth-colored restorative materials before and after immersion in acidic and alkaline solutions. METHODS: Specimens were prepared from three resin composites; Ceram X, Filtek Supreme, Point 4, two polyacid-modified resin composites; Dyract, F2000, and one resin-modified glass-ionomer cement; Fuji II LC, immersed in distilled water for 24 hours at 60 degrees C, polished with silicon carbide papers up to 2000-grit and subjected to baseline measurement for Vickers hardness or shear punch strength. Further specimens were transferred to one of four aqueous media at 60 degrees C for a further 2 weeks; distilled water, 0.01 mol/L lactic acid, 0.1 N NaOH or coffee 15 g/500mL, washed, dried and tested for final hardness or shear punch strength. RESULTS: Data analysis using ANOVA and Tukey's test showed that the hardness and shear punch strength values were material and solution dependent. Regardless of the solutions; the hardness of F2000 was the highest and Fuji II LC the lowest; Point 4 and Filtek Supreme had the highest shear punch strength; Fuji II LC and F2000 had lowest. NaOH significantly reduced the hardness of all materials and completely dissolved the structure of Fuji II LC. Lactic acid and coffee significantly increased shear punch strength compared to baseline.