Aims: The purpose of this study was to investigate the effect of different post space preparation techniques and times on the apical seal of two types of gutta-percha obturation techniques. Materials and methods: Two hundred extracted human lower premolars were selected for this study. All teeth were decoronated to adjust the working length at 14 mm. The canals were instrumented with ProTaper rotary instruments to size F3. The (200) root canals were randomly divided into two groups (100) of each according to the obturating method. Then each group was sub divided into (10) sub groups (10) of each (2 control groups and 8 experimental groups). Nine mm segment of gutta-percha was removed from the roots in each of the experimental groups either immediately after obturation or 7 days later using either heated pluggers, or Gates-Glidden drills or ProTaper rotary instruments or peeso reamers. The roots in the control groups were left without any post space preparation. The canal orifice of the roots in the experimental groups was sealed with amalgam. The extend of linear dye leakage was measured in mm with a stereomicroscope at (X 20). One-way ANOVA and sheffe statistical analysis were performed to the data collected. Results: The groups with ProTaper rotary instrument prepared the post space immediately after obturation( gps 3,11), showed the lowest mean leakage, but the difference was not statistically significant than the other experimental groups. T-test represented no significant differences existed at either two time interval studied and the type of obturation techniques. Sheffe-test for the post space preparation techniques revealed that there were a significant differences occurred with the use of ProTaper rotary instruments regardless the time interval and the obturation techniques. Conclusions: ProTaper rotary instrument provided less microleakage comparing to the other instruments used to prepare the post space. The post space preparation did not affect the apical seal in comparison with that of the intact filling. Abstract:Apical seal in root canal after post space preparation Al -

Article InfoThe present study was carried out to investigate heavy metal accumulation inthirtythree soil samples from different depths and six vegetable samples and to assess the human health risks of vegetable consumption. Four vegetable types (cress, leek, chard and celery) were irrigated with wastewater cultivated on farmland contaminated with heavy metals (Cu, Pb, Zn, and As) from Khassa river of Kirkukcity. The order of heavy metal concentration was found in Zn > Cu>Pb>As in vegetable samples and Zn > Cu>Pb>As was observed in soil samples. The health risk assessment methods include target hazard quotient (THQ) and hazard quotient (HQ) were used to assess the human health risks posed by heavy metals through vegetable consumption.

Aim:To evaluate the surface roughness of three different types of light activated composite resin using (Sof-Lex)polishing system, a profilometer study. Materials and Methods: A total of 30 resin composite disks were prepared from three different types of composite resin include 3groups. Group I: 10 specimens were prepared from light activated nano hybride (Tetric n -Ceram, Ivoclar -Vivadent -Liechtenstein). Group II: 10 specimens were prepared from light activated microhybride composite resin (Arabesk -Voco, Germany). Group III: 10 specimens were prepared from light activated polyglas composite resin (Solitaire -2, Heraeus, Kulzer, Germany). The resin blocks finished and polished using (Sof -Lex) polishing system. The specimens were analyzed for surface roughness using "Profilometer". Results: Tetric n -Ceram composite resin showed the lowest roughness average (0.112 µm) followed by Arabesk composite (0.150 µm), Solitaire -2 composite resin showed the highest roughness average (0.341 µm). Conclusions: Tetric n-Ceram (nano-hybride) was the best polished composite resin, showed the least roughness average.

Nayif A Jado EngineerABSTRUCT Aims: The aim of this study was to investigate the effect of storage time (immediately after polymerization and after one month of artificial saliva storage) on the degree of conversion (DC) of restorative type of light cured dental materials. Materials and Methods: Sixty samples of polyethylene molds were prepared. The samples were divided into three groups each of 20. The first group was filled with Composite resin, second group was filled with Compomer and the third group was filled with Resin modified glass ionomer cement (RMGIC). Each group was subdivided into two subgroups; each of ten according to storage time: The DC was tested for the first subgroup immediately after polymerization, while the DC of the second subgroup was tested after one month of storage in artificial saliva. The DC was investigated by Fourier-transform infrared spectroscopy (FTIR). Results: ANOVA test was used for statistical analysis. The results showed that there was a significant difference (p<0.05) in DC between the subgroups tested immediately after polymerization and the subgroups tested after one month of artificial saliva storage for Composite resin and Compomer. While RMGIC showed no significant difference (p>0.05) in DC between the subgroup tested immediately after polymerization and the subgroups tested after one month of artificial saliva storage. Conclusions: One month storage time has an effect on the DC of Composite and Compomer, but it has no effect on the DC of RMGIC.

The aim of this study was to determine the effect of storage time on shear bond strength of three composite resin, two utilize total etch technique and one utilize self etching bonding agent. One hundred twenty maxillary and mandibular molars were used in this study. The teeth were prepared by cutting the occlusal enamel with diamond bur to expose dentin and ground wet with silicone carbide papers. The specimens were then divided into three groups and stored in distilled water. Scotchbond Multipurpose Plus was used in the first group and a stainless steel round mould, with a central hole of 4 mm in diameter and 2 mm in height was used to build up the composite Z100. The composite resin was inserted in two increments, each one was light cured for 40 seconds. This group is divided into four subgroups each of ten according to the storage time (one day, fifteen days, three months and six months) then stored in distilled water accordingly. The same procedure was repeated in the second and third groups. The composite used in the second group was Tetric with Excite bonding agent. In the third group, Definite composite and its bonding agent Etch and Prime was used. The bond strength was measured and the data were statistically analyzed. Z100 composite had the greatest shear bond strength followed by Tetric and Definite. One day and fifteen days storage time for all types of composite had greater shear bond strength than the three months and six months storage time. In conclusion there was a gradual decrease in bond strength with increased storage time up to six months irrespective of the type of composite.