Purpose: To evaluate the shear bond strength of a new generation of glass ionomer (Glass Carbomer) to enamel versus a nano-filled resin-modified glass ionomer (ketac Nano) and a conventional type after different storage periods. Materials & methods: Crowns of 36 sound and freshly extracted human permanent molars were sectioned mesiodistally into two halves. The convex buccal or lingual surface was gently ground with water cooled 200-, 400-, and 600-grit silicon carbide abrasive papers successively to obtain flat enamel surfaces. The prepared specimens (n ¼ 72) were divided into three main groups (24 each): I (Ionofil Molar), II (Ketac Nano) III (Glass Carbomer). The specimens in each group were subdivided into three subgroups A, B & C according to the storage period in artificial saliva. Shear bond strength between enamel surface and the bonded material was measured using a universal testing machine at a cross head speed of 0.5 mm/min. All the debonded interfaces were examined under both binocular stereo microscope at 40Â and SEM at 200Â to determine the mode of failure. Results: Ketac Nano recorded the highest shear bond strength values (9.30 ± 0.67, 12.07 ± 0.76, 6.7 ± 0.73) followed by Ionofil Molar, recording (5.25 ± 0.62, 7.82 ± 1.42, 5.91 ± 0.87) while the lowest values were found in Glass Carbomer specimens, recording (2.17 ± 0.63, 6.66 ± 0.68, 5.72 ± 0.79). There was a highly significant difference in shear bond strength values among the three different storage periods in all the tested materials (P < 0.0001). A positive correlation was recorded (R ¼ 9.3) between the adhesive mode of failure and shear bond strength while a negative correlation was recorded (R ¼ 4.5) between the cohesive mode of failure and shear bond strength using Spearman's correlation test. Conclusions: Storage time was a factor which significantly influenced both shear bond strength and mode of failure especially in Glass Carbomer specimens.

Purpose: To evaluate the clinical performance of two nano-hybrid giomer restorative composites; Beautifil II and Beautifil Flow Plus F00 with FL-Bond II adhesive system in class I posterior restorations during three-year period. Materials and methods: Twenty patients joined this study with age ranging from 20 to 35 years. Each patient has to present two permanent upper or lower molars of the same side requiring new class I restorations of primary carious lesions to be restored by both tested materials. Two clinicians examined the twenty patients with 40 restorations (20 for each restorative material) clinically using Modified USPHS/Cvar & Ryge Criteria for direct restoration for a period of three years with an examination interval 6 months. Results: Data was collected and statistically analyzed using SPSS version 18. Friedman's test showed no significant changes to all modified USPHS criteria for each material during the three-year evaluation period. Fisher's exact test showed no significant changes between materials in postoperative sensitivity, recurrence of caries or retention of restoration. The significant changes recorded were after three years period follow up between the two materials; Beautifil flow plus F00 has significantly better marginal adaptation (P < 0.01), marginal discoloration (P ¼ 0.01), surface roughness (P ¼ 0.01) and surface morphology (P < 0.01) versus Beautifil II. Conclusion: Beautifil Flow Plus F00 (zero flow) restorative material achieved clinically better significant acceptable results than Beautiful II after three years of service in conservative class I cavities.

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