Khaled Mahmoud Fawzy, Mohamed Moustafa Abdel-Moaty, Nermin AlSayed Mahmoud And Asmaa Abdel-Hakeem Metwally,

ABSTRACT


Aim: The Objective Of This In Vitro Study Was To Evaluate The Effect Of Incorporation Of Nano-hydroxyapatite Particles With Three Different Proportions (1 %, 5% And 10%) In To Glass Ionomer Cement (GIC) On Shear Bond Strength To Dentin, Water Sorption And Water Solubility.

Materials & Methods: Experimental Material Powder Was Prepared By Mixing Different Wt% (1%, 5% And 10%) Of Nano-hydroxyapatite (HA) Powder With GIC Powder (GC Gold Label 9 Posterior Restorative) And Evenly Mixed By A Spatula On A Glass Slab. A Total Of Eighty Specimen From GICs [GIC Control (Group I), GIC+1%NH (Group II), GIC+5%NH (Group III) And GIC+10%NH (Group IV)] Were Prepared According The Manufacturer Instructions [Powder / Liquid Ratio (3.6g/1.0g)], Divided As Forty Specimen For Each Test. For Shear Bond Strength Test; Forty Human Posterior Teeth Were Used In This Study. Ten Disks Of 5mm Diameter And 2mm Thickness From Each Tested Material (n=10) Were Prepared And Bonded To Occlusal Dentin Surface Beyond The Dentino-enamel Junction. The Specimens Were Removed From The Molds After 30 Min, And Then Stored At 37?C For 24 Hour. Universal Testing Machine Was Used To Measure The Shear Bond Strength Between The Tested Material And Dentinal Surface. Another Ten Disks Of 10mm In Diameter And 2mm Thickness From Each Tested Material (n=10) Were Prepared For Water Sorption And Solubility Tests. After Complete Setting Of The Specimens, The Original Mass Of Each One (M1) Was Recorded By Using The Digital Balance With An Accuracy Of 0.1 Mg, Then Transferred To Separate Test Tubes Contained Distilled Water And Stored In An Incubator At 37?C For One Week After That, Wet Mass (M2) Then Each Disk Was Placed In A Silica Particles-containing Desiccator And Weighed Daily Within 7 Days To A Constant Finalmass (M3) To Allow Determination Of The Mass Loss. Data Were Collected, Tabulated And Statistically Analyzed By Using One-way ANOVA Followed By Tukey Post Hoc Test.

Results: There Was A Statistically Significantdifference Between Groups Where (p<0.001). The Shear Bond Strength And Water Solubility Of GIC With 10% Nano-hydroxyapatite GIC+10%NH (G4) Had The Highest Values (3.249?0.152MPa) And (252.46 ?9.06 Ug/mm3) Respectively. GIC With 5% Nano-hydroxy-apatite GIC+5%NH (G3) Had The Highst Value In Water Sorption (301.58?12.33 Ug/mm3).

Conclusions: Incorporation Of Nano-hydroxyapatite Particles Within Glass Ionomer Cement Enhanced The Shear Bond Strength Between The GIC And Dentin, Also Increased The Water Sorption And Solubility Of GIC Which Affect Its Physical Properties.

Basma Osama Abbas Ghonim, Dina Magdy El Shehawi And Gihan Abd-El Hady El Naggar,

ABSTRACT


Aim: The Study Was Conducted To Assess The Fracture Resistance Of Zirconia Reinforced Lithium Silicate All Ceramic Material ?Celtra Press? Compared To Lithium Disilicate One ?IPS E-max Press? Under Simulated Oral Conditions.Methodology: Fourteen Ceramic Crowns Were Fabricated On Epoxy Dies Which Were Duplicated From Stainless Steel Master Die And Divided Into Two Equal Groups (n=7) According To The Material Of Construction; Group A: Crowns Fabricated With IPS E-max Press Material And Group B: Crowns Fabricated With Celtra Press Material. The Crowns Were Then Cemented Onto Their Corresponding Dies With A Self-adhesive Resin Cement And Subjected To Thermocycling And Cyclic Loading. Then They Were Loaded To Fractur In A Universal Testing Machine. The Results Were Tabulated And Statistically Analyzed Using Kolmogorov-Smirnov And Shapiro-Wilk Tests. Student T-test Used To Compare Mean Values. The Significancelevel Was Set At P ? 0.05 And 95% Confidenceinterval. Statistical Analysis Was Performed Using Graph Pad Instat (Graph Pad, Inc.) Software For Windows

Results: The Mean ? SD Values Of Fracture Resistance Were Recorded For Lithium Disilicate Group (1706.01 ?154.32 N) Meanwhile The Mean ? SD Value Recorded With Celtra Group Were (1550.67?196.71 N). Conclusion: Zirconia Reinforced Lithium Silicate Ceramic Crowns Produced Comparable Fracture Resistance Values To Lithium Disilicate Ceramic Crowns And Both Tested Materials Are Within The Clinically Acceptable Values In The Posterior Area.