الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Summary
To date, the use of GIC in pediatric dentistry has increased drastically owing to its advantages
being biocompatible, its capability of bonding to the tooth structure and its fluoride release. On
the other hand, the brittle nature of the material as well as its solubility affects its durability
as a restoration. Knowing that repairing the defective restorations would be a more conservative
approach, would prevent any accidental pulp injury and would be a less time consuming procedure.
Accordingly, this study was designed to assess the repair bond strength of two different GICs using
various bonding methods.
Forty intact hourglass slabs of two GICs, a RMGIC and a HVGIC (Ionolux AC and Ionofil Molar AC
respectively, VOCO, Germany) were prepared and served as a control (n=20 each) to evaluate the
cohesive strength after 24-hours (n=10) and 6-months (n=10) storage periods. Eighty half hourglass
slabs were divided into two main groups (n=40 each) according to the material used and stored in
water for 6 months. After 6 months, the half slabs were divided into 2 subgroups (n=20 each)
according to the presence or absence of surface grinding. Each of the above subgroups was
divided into 2
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divisions (n=10) according to the application of 25% PAA (PAA, 3M ESPE, AG, Germany). The
repair procedure was carried out by adding new material to the aged one and the slabs were
stored in distilled water for 24- hours.
The TBS of both whole and repaired slabs was evaluated using the Universal Testing Machine at a
crosshead speed of 0.5mm/min. All fractured surfaces of the aged material were evaluated to assess
the type of failure. Statistical analysis was carried out using SPSS program (SPSS, 2008).
Two-way ANOVA revealed that glass-ionomer type and bonding methodss had a significant effect on
TBS. The interaction between the two independent variables (glass-ionomer type and bonding method)
had also a significant effect on the repair bond strength.
The analysis of failure modes using digital microscope showed
that 47 % of the fracture mode was ‘mixed’, 22.5 % was ‘adhesive’,
17.5 % was ‘Cohesive in the new material’ while 1.25 % was cohesive in the old
material’.
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Conclusion
Under the limitations of this study, several conclusions could be deducted:
1. Repair of RMGIC can be a clinically accepted procedure.
2. It is mandatory to grind the surface of RMGIC before the repair procedure.
3. The application of PAA did not add any advantage on the repair potential of both HVGIC and
RMGIC.
4. The repair of HVGIC is not an easy procedure and needs further investigation.
Recommendations
1. Further investigations are needed to study the effect of different bonding methods on the
repair of different GICs.
2. Repair of RMGIC is preferred over HVGIC used in this study.
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