الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
To date, there are various types of restorative materials in the market that are suitable for use as filling materials for primary teeth. Among these materials were the newly introduced flowable colored PAM-CR. Owing to its flowable nature and color, it was suggested that these materials would be more accepted by children and would favor the needs of operator in terms of better adaptation to cavity walls, less incorporation of air voids, ease of application and acceleration of the filling process.
Accordingly, this study was formulated in an attempt to test the flowable colored fluoride releasing polyacid-modified composite resin (PAM-CR) material and compare it to the most commonly used fluoride releasing filling materials in pediatric dentistry such as; resin-modified glass ionomer cement(GIC), tooth-colored PAM-CR and flowable resin composite. This study was divided into two parts; an in-vitro study and an in-vivo study in order to try to correlate some laboratory properties with the clinical performance of the tested materials.
In-vitro study
a) Flexural Strength:
Four hundred rectangular specimens were prepared in standardized mold. Specimens were divided into five main groups (n=80 each) according to the material under study.Specimens were further divided into 4 sub-groups (n=20 each) according to the designated storage time: 24 hours, 3, 6, and 12 months.Specimens were tested for flexural strength using the Universal Testing Machine (LR5K series, LIoyd Instruments, Ltd, UK).
Results showed that the type of material used as well as the time and the interactions between the two independent variables (material type and storage time) had a statistically significant effect on the flexural strength of the materials under study.
b) Microhardness:
One hundred disc shaped specimens were prepared in standardized mold. Specimens were divided into five main groups (n=25 each) according to the material under study.Specimens were further divided into 4 sub-groups (n=5 each) according to the designated storage time: 24 hours, 3, 6, and 12 months.Specimens were evaluated for microhardness using the Nexus 4000 TM Vickers Microhardness tester (INNOVATEST Europe, BV, Borgharenweg, Netherlands)
Results showed that the type of material used as well as the storage time and the interactions between the two independent variables (material type and storage time), had a statistically significant effect on the microhardness of the materials under study.
c) Surface Roughness:
One hundred disc shaped specimens were prepared in standardized mold. Specimens were divided into five main groups (n=25 each) according to the material under study.Specimens were further divided into 4 sub-groups (n=5 each) according to the designated storage time: 24 hours, 3, 6 and 12 months.Specimens were evaluated for surface roughness using the stereomicroscope under 25x magnification and image J software was used for analysis.
Results showed that the type of material used as well as the storage time and the interactions between the two independent variables (material type and storage time) had a statistically significant effect on the surface roughness of the materials under study.
d) Degree of Conversion
Twenty-five disc shaped specimens were prepared in standardized mold. Specimens were divided into five main groups (n=5 each) according to the material under study. Specimens were evaluated for the degree of conversion at 24 hours using the Fourier Transform Infra-Red (FTIR) spectrometer (Thermo-Nicolet Nexus 670 FTIRc).
Results showed that the type of material used had a statistically significant effect on the degree of conversion.
e) Fluoride Release
Fifty disc shaped specimens (10 discs from each material) were prepared in standardized mold.Each disc was stored separately in a plastic container encompassing 10ml de-ionized water. Specimens were retrieved from water, rinsed, and placed in a new container before each measurement. The rinsing water added to the storage water was tested according to the designated storage time: 24 hours, 7 and 28 days. Specimens were evaluated for fluoride release using ion chromatograph device (ICS-1100, Thermo, DX 100, Dionex, Camberley, UK)
Results showed that the type of material used as well as the interactions between the two independent variables (material type and storage time), had a statistically significant effect on the amount of fluoride released. On the other hand, the storage time had no statistical significant effect on the amount of fluoride released.
f) Fluoride Recharge-ability
The previously mentioned discs used in fluoride release were retrieved from the de-ionized water after 28 days of storage. Discs were recharged by applying fluoride varnish containing 5% NaF (ProShield Varnish, President Dental, Germany) and evaluated for fluoride recharge-ability using ion chromatograph device (ICS-1100, Thermo, DX 100, Dionex, Camberley, UK) at 24-hour, 7, and 28-day storage periods.
Results showed thatthe type of material used, storage time as well as the interactions between the two independent variables (material type and storage time) had a statistically significant effect on the amount of fluoride recharge-ability.
In-vivo Study
One hundred restorations were placed in Class I cavities (n=20 from each material under study) in 50 systemically healthy subjects between the age of 4 to 7 years. Cavities were prepared in upper or lower first and/or second primary molars with detectable pits and fissures caries by clinical and radiographic examinations. Each patient received two restorations from the same material. Two trained calibrated evaluators evaluated the restorations at 24 hours, 3, 6, and 12 months using the United States Public Health Services criteria (USPHS).
A written questionnaire was carried among children in an attempt that each child would pick his/her preferred filling material color and state his/her feeling towards the color of the filling material chosen.
Results showed that most of the restorations, from the five materials under study, were clinically acceptable and none required repair nor change over the 12-month storage period.As for the questionnaire, almost all boys preferred the blue color of restorations toother colors. Likewise, almost all girls preferred the pink color of restorations toother colors. They also showed a happy attitude towards the dental experience with the colored filling material.