Abstract: Aims: The aim of this study is to assess the prevalence of Angle’s molar classification and recording sagittal malocclusion, among (15- 18) years-old-school students; by studying two factors: gender and the socio-economic status, which are represented by the school type as private or public schools. Materials and Methods: In this cross-sectional study, a total of 593 aged between 15 – 18 years old. Students were included from randomly selected male, female and mixed high schools. Distributed in different areas in Erbil city. Excluding those who previously had orthodontic treatment, orthognathic surgery, missing upper or lower first molar, and students with any contagious diseases. The molar relationship was determined by direct clinical examination according to Angle’s classifications and sub-classifications. Statistical analysis was obtained using SPSS (Statistical Package for the Social Sciences). Pearson Chi-Square test was used to determine the significance among the data’s variables. Results: The findings showed 90.2 % of the subjects had malocclusion, and the prevalence of malocclusion was as the following: Class I 59.1%, Class II 24.7%, Class III 16.2%, respectively. According to gender, Chi-square was significant in molar classification and sub-classification. As for the school type, Chi-square was not significant in molar classification, but it was significant in sub-classification at p-value ≤0.05. Conclusions: Malocclusion is relatively high in Erbil city among adolescents.      

Abstract: Aims: The study intended to inspect the consequence of the addition of zirconium oxide (ZrO2) nanoparticle at two concentrations (1% and 1.5% by weight) on the surface roughness of the maxillofacial silicone material (room temperature vulcanized).  Materials and methods: Thirty samples were prepared according to the manufacture instructions and divided into three groups (n=10). A digital surface roughness profilometer tested the surface roughness samples for the control group (A) free from nanoparticle, group (B) 1% ZrO2, group (C) 1.5 % ZrO2. Results: The mean values of the surface roughness measured groups a highly significant difference among groups. Group A (.2137 µm) exhibited a highly significant difference compared to group B (.2698 µm) and group C (.2801 µm). Besides, a highly significant difference between group B and group C. Conclusions: Incorporation of 1% and 1.5% by weight of ZrO2 nanoparticle into maxillofacial silicone material increases surface roughness.

Abstract: Aims: The aim of this in-vitro study was to compare the retention force of Polyetheretherketone (PEEK) and Cobalt-Chromium (Co-Cr) clasps by mechanical cycling test simulating ten years of use. Materials and Methods: 72 clasps samples were fabricated on a standardized e-max upper right first premolar, it is divided into 24 Co-Cr clasps, and 48 PEEK clasps which were subdivided into 24 clasps (2.4mm width), and 24 clasps (3.00mm width).Each group was further subdivided (n=8 clasps) into amounts of abutment undercut 0.25mm, 0.50, and 0.75mm undercuts. Mechanical cycling of each clasp was performed for 15000 times on its specific abutment crown. The retention force of each clasp in newton was measured every 1500 cycles by applying a tensile force using a universal tensile machine. Results: The retention force of Co-Cr clasps was higher significantly than the PEEK clasps retention force for the three undercuts. Deeper undercut showed a significantly higher retention force for both materials. All subgroups (except 0.75mm Co-Cr group) exhibit an increase in retention force after first 1500 cycles followed by gradual decrease till the end of 15000 cycles. Conclusions: The retention force of PEEK clasps with both widths along 15000 cycles of insertion/removal were lower than Co-Cr clasps but still sufficient for clinical use at 050, and 0.75mm undercut but not enough at 0.25mm undercut.

Abstract: Aims: This in-vitro study aimed to compare the fatigue deformation of Polyetheretherketone (PEEK) and Cobalt-Chromium (Co-Cr) clasps by mechanical cycling test simulating ten years of use. Materials and Methods: 72 clasps samples were fabricated on a standardized e-max upper right first premolar; it is divided into 24 Co-Cr clasps, and 48 PEEK clasps which were subdivided into two halves (2.4, and 3.00) mm width respectively. Each group was further subdivided (n=8 clasps) according to the amounts of abutment undercut (0.25, 0.50, and 0.75) mm respectively. Each clasp was digitally pictured by a microscope before cycling, and then mechanically cycled by a specifically designed insertion-removal apparatus for 15000 times on its specific abutment crown, and at the end of 15000 cycles, each clasp was digitally re-pictured, and the distance between the clasp tips in millimeter of the pre and post cycling pictures were measured with specific analyzing computer program. Results: The fatigue deformation of Co-Cr clasps was higher significantly than the PEEK clasps for the three undercuts. Deeper undercuts showed a significantly higher fatigue deformation for Co-Cr clasps but not significant for PEEK clasps. Conclusion: The fatigue deformation of PEEK clasps with both widths after 15000 cycles of insertion/removal was lower than Co-Cr clasps fatigue deformation.

Abstract: Aims: to investigate serum biochemical changes (malondialdehyde levels and T-AOC) and the histopathological changes of salivary glands. Materials and Methods: Twelve healthy mature male rabbits were included in the study.Group one (6 animals): the rabbits were maintained on a standard diet and water without any treatment for 30 days.  Group two (6 animals): the rabbits were given) NaF at the dose of 20 mg/kg/day (dissolved in 400 ml of distilled water for 30 days. At the end of one month of treatment, the animals were sacrificed and (5ml) of blood samples were taken from all animals via jugular vein during the animal sacrificing. Serum were separated from all samples and stored at -20 ˚C till time of analysis by colorimetric Assay kit for both total antioxidant capacity (T-AOC) by (Elabscience, Cat. No. E-BC-K136-S, TBA method) and malondialdehyde (MDA) by (Elabscience, Cat.No.E-BC-K025-S, TBA method).Tissue samples from parotid and sub-mandibular salivary glands were isolated and examined under a light microscope for histopathological changes. Results: Significant differences were founded between the values of serum biochemical markers between control and treatment groups. T-AOC in control group was higher than in treatment group, while MDA level in treatment group was higher than control group. Sections of the parotid and submandibular glands taken from the control group appeared to have the normal histological structure compared to the treated group, which showed an acute inflammatory cell infiltration, Hyperemia with thickening of blood vessels wall. Conclusions: NaF at dose of 20 mg/kg/day for 30 days can lead to a decrease in T-AOC with considerable inflammatory changes in tissues of salivary glands of rabbits.

Abstract: Abstract: Malocclusion bearings a great weight internationally. Persistent oral habits produce alteration in the activity of orofacial muscles. Early diagnosis and treatment of the orofacial myofunctional disorders render countless welfares by minimizing related malocclusion and reducing the possibility of relapse after orthodontic treatment. Pre orthodontic trainers are innovative types of prefabricated removable functional appliances claimed to train the orofacial musculature; thus correcting malocclusion. This review aimed to search the literature for studies and case reports on the effectiveness of pre-orthodontic trainers on early correction of developing malocclusion and highlight particularly on its structural characteristics and its mechanism of action. Current literature provides sufficient evidence that these appliances are effective in treating Class II malocclusions especially those due to mandibular retrusion. Case reports on Class I malocclusion have reported relief of anterior crowding, alignment of incisors, and correction of deep bite with pre-orthodontic trainers. Promising results with pre-orthodontic trainers are realized in improved nasal breathing, improved swallowing pattern, and removal of habits like tongue thrusting and mouth breathing.

Abstract: Aims: Evaluate the ability of different a bulk-fill flowable composite sealing around class I cavities compared to conventional composite. Materials and Method: Forty upper premolar teeth prepared with an ideal class I, then distributed according to types of composite resin into four groups (n=10): group I= filling with SDR, group II= filling with Sarmco flowable composite resin, group III= filling with Tg flowable composite resin, finally group IV= filling with Valux plus composite resin (as a control) polymerized by LED light cure unit, varnished and placed in 2% methylene blue then sectioned bucco-palatally. The Micro-leakage was determined by stereomicroscope. Results: There was a significant difference (p<0.05) in mean micro-leakage values between SDR (group I) and Saremco (group II) while there was no significant difference (p>0.05) in micro-leakage values between SDR (group I) and Tg (group III) and Valux plus (group IV). Conclusion: SDR can be applied in 4 mm as a lone layer without negative effect on micro-leakage.

Abstract: Aims: The study aimed to estimate the in vitro effect of a cocoa bean husk extract (CBHE) mouth rinse in comparison with that of a fluoridated mouth rinse on microscopic features of enamel surface after subjecting the teeth to two types of energy drink challenge. Materials and Methods: Twenty sound maxillary first premolars were collected and randomly divided into four groups, the teeth in the first two groups were immersed in the tiger energy drink for 14 days, then the teeth in the first group were exposed to a CBHE mouthwash and the second group was exposed to a fluoride mouth wash for 7 days. While the remaining teeth in the second two groups were immersed in the red bull energy drink for 14 days, then one group in a CBHE mouth wash and the other in a fluoride mouth wash for 7 days. Enamel surface was evaluated by a polarized light microscope at a baseline, after erosive challenge and after remineralization with the different treatment materials. Results: Microscopic images confirmed that prolonged subjection of dental sample to energy drink could crack or erode the tooth surface and between the two energy drinks, tiger energy drink had a somewhat more destructive microscopic feature. Besides that, both mouthwashes were efficient in re-mineralizing the defected area, and CBHE mouth wash revealed somewhat a high amount of remineralization which appeared in the polarized light microscope images being more dark areas in comparison with fluoride groups . Conclusion: Within the limits of the current study, CBHE and fluoride mouth rinses had an effective re-mineralizing ability after erosive energy drinks which had a destructive effect on tooth enamel. CBHE mouth wash showed somewhat a high ability of remineralization when compared with fluoride groups 

Abstract: Aims: The aims of this study were to evaluate the in vitro effect of a cocoa bean husk extract (CBHE) mouthwash in comparison with that of a fluoridated mouthwash on surface roughness of the enamel surface after subjecting the teeth to two types of energy drink challenge. Materials and Methods: Eighty (80) sound maxillary first premolar were collected and randomly divided into four groups, the teeth in the first and second groups were immersed in a tiger energy drink for 14 days and then one group in a CBHE and another in a fluoride mouth rinses for 7 days. While the remaining teeth in the third and fourth groups were immersed in a red bull energy drink for 14 days and then one group in a CBHE and another in a fluoride mouth rinses for 7 days. Enamel surface was assessed by a profilometer device at a baseline, after erosive challenge and after remineralization with the different treatment materials. Results: In all groups, there was a high statistically significant increase in surface roughness after erosive challenge. Meanwhile, there was a high statistically significant decrease in surface roughness in all groups after remineralization, with no significant differences between energy drinks or remineralization materials. Conclusion: Within the limits of the current study, cocoa bean husk extract and fluoride mouth rinses had an effective remineralizing ability after erosive energy drinks which have a destructive effect on tooth enamel. CBHE mouth wash showed a similar remineralization effect to fluoride groups.

Abstract: Aims: This study aims to assess the impact of the addition of MgO nanoparticles(NPs) with size of 50nm at different concentrations,which are 1.25%,2.5% and 5%  on adherence of Candida albicans to cold- cured acrylic resin. Materials and Methods: Twenty-four specimens with the dimensions of (10mm ×10mm×2mm)length, width, and thickness respectively were made and divided into four groups, 6 specimens for each group; controlled (without the addition of  MgO NPs) ,group of 1.25% MgO NPs ,group of 2.5% MgO NPs and group of 5% MgO NPs; were subjected to adherence test. The statistical analysis was done by using SPSS program including descriptive statistics, ANOVA, and the Duncan΄s test at p ≤ 0.05. Results: Results showed that, the maximum reduction in Candida albicans adherence obtained at a concentration of 5% followed by 2.5% then 1.25% ; while the control group showed that the highest number of Candida albicans colonies  adhered to cold-cured acrylic. Conclusions: The MgO NPs influenced the adherence of Candida albicans to cold-cured acrylic resin, there is a significant reduction in the number of Candida albicans attached to cold-cured acrylic modified with MgO nanoparticles at different concentrations;and this reduction  increases with increasing the concentration of MgO nanoparticles.

Abstract: Aims: This study investigates the effects of the addition of magnesium oxide Nanoparticles(MgO NPs)  with size (50 nm) on the flexural strength of cold˗cured acrylic resin. Materials and methods: Forty acrylic specimens were made, which divided into four groups (10 specimens for each group) which were control group (pure acrylic without addition), group of acrylic specimens containing 1.25% MgO NPs,  group of acrylic specimens containing 2.5%MgO NPs, and a group of acrylic specimens containing 5%MgO NPs, the flexural test was performed using the universal testing machine, FTIR test performed using (BRUKER LASER CLASS 1). The statistical analysis was done by using  SPSS program including descriptive statistics, ANOVA, and the Duncan΄s test at p ≤ 0.05. Results: The Maximum mean of flexural strength belong to the group with 1.25% of MgO NPs,the minimum mean of flexural strength belongs to a group with 5% MgO NPs.  Conclusion: The addition of  MgO NPs affected the flexural strength of the cold-cured acrylic resin, it improved the flexural strength at low concentration but decreased it at higher concentratios.

Abstract: Aims: Assess the quantity of apical extruded debris after instrumentation with ProTaper universal files, K3 files, and Wave One reciprocating file. Materials and Methods: Thirty lower premolars were used in this study. Teeth were randomly divided into 3 groups each one contained 10 samples as follow: Group1- Teeth were prepared with ProTaper universal files. Group2- Teeth were prepared with K3 files. Group3- Teeth were prepared with Wave One file. Debris that was apically extruded during canals preparation was collected in the centrifuge tubes, which previously were weighed. Centrifuge tubes were put for 5 days in the incubator with temperature of 70 °C to allow evaporation of moisture. After that centrifuge tubes that contained debris were weighed, and quantity of extruded debris was determined via subtraction the initial weight of centrifuge tube from the final weight of same tube, then collected data was analyzed statistically. Results: Statistical analysis revealed that, ProTaper group showed highest amount of apical extruded debris followed by Wave One group and, K3 group showed least amount of apical extruded debris. The difference between ProTaper group and Wave One group was not significant, but both of them had significant difference with K3 group. Conclusions: Within the limits of the current study, preparation of root canals with K3 files is better than other groups in terms of less extrusion of apical debris.

Abstract: Aims: To compare the apical sealing ability of TotalFill BC, AH Plus Jet, and GuttaFlow Bioseal sealers. Materials and Methods:  Thirty single rooted mandibular premolars were decoronated and standardized at 15mm. The specimens were chemo- mechanically prepared, and randomized into three experimental groups (n =10) according to the root canal sealer tested: TotalFill BC, AH Plus Jet and, GuttaFlow Bioseal. The specimens were filled using single cone technique. The specimens were decalcified, dehydrated, and cleared. The specimens were analyzed by stereomicroscope, and digital images were captured using stereomicroscope attached camera. The apical dye leakage depth was measured and evaluated using four grade scoring system at 10X magnification. The apical micro leakage data among experimental groups were statistically analyzed by one way analysis of variance (ANOVA) test and Fisher’s exact test at 5% significance. Results: Statistically, there was no significant difference in apical micro leakage among the experimental root canal sealers. (P> .05) Conclusions: In this study, no experimented root canal sealer had perfect sealing ability. The experimental root canal sealers were similar in their sealing ability at apical area of root canal.

Abstract: Aims: To evaluate the effect of incorporation of different types and concentrations of additives on water sorption denture base acrylic resin. Materials and Methods: Heat polymerized acrylic resin samples were prepared and divided into two groups; control group (without additives) and experimental group (with additives). The additives were three types of polymers (Styrene Butadiene Rubber (SBR), Poly Ethylene Glycol (PE) and Poly Urethane (PU)) being added with three concentrations 1%, 3% and 5%. SPSS Version 19 was used to analyze and to assess the results of the present study by mean of Descriptive statistics, analysis of Variance (ANOVA) and Duncan multiple range tests at p ≤0.05. Results: The results reveal that there is statistically significant reduction in the amount of water sorption of experimental group as compared to that of control group at p≤ 0.05. The reduction in the amount of water sorption of experimental group is directly proportional to the concentration of incorporate additives.  Conclusions: Water sorption of experimental group is less than that of control group. The additives produce statistically significant reduction in the amount of absorbed water of denture base resin and this reduction was directly proportional to the concentration additives material being used.

Abstract: Aims: To investigate the reasons for replacement of composite restorations northern Iraq. Method: Seventy general dental practitioners (GDP) were recruited by personal contact, and asked to provide data on consecutive composite restorations they replaced for adult patients (ranged from 14-year-old to 60 years) over an eight-month period. In addition, a cross-sectional survey was carried out over eight months at the undergraduate student clinics of a University Dental Hospital (DS). The data was analyzed using SPSS software with significance set at p≤0.05. Results: Of the performed 1,338 restoration replacements. The types of restorative materials were 395 (30%) were amalgam, 929 (69%) were composite and 14 (1%) were glass ionomers (GIC). Secondary caries was the most diagnosed failure reason for the replacement of composite restorations (32%), which were more in class II cavities (47%). Conclusion: The study exposed different features of the restorative practice in the north of Iraq. The evidences are of importance that the everyday restorative practice will be analyzed by academics to make a progression in the dental services in Iraq.

Abstract: Aims: To evaluate the effect of the addition of MgO, ZrO2, ZnO nanoparticles in different concentration to acrylic based soft liner on candida Albicans adhesion. Materials and methods: acrylic-based soft-liner samples were prepared (10 X10 X 2mm dimension) by addition MgO, ZrO2, ZnO nanoparticles in 0.25, 0.5, 1, 2, 4 % by weight concentration to the monomer resin, the samples were immersed in Candida Albicans suspension for 1 hour then washed and dried, the microorganism were fixed and stained by crystal violet and examined by light microscope (at 400 x) to enumerate the stained candida Albicans in two occasions for thirty fields of view. Result: soft liner with 1,2,4 % by weight demonstrated that a decreased the surface adhesion of candida Albicans when compared with control group while specimens with lower concentration (0.25, 0.5% by weight) show no significant difference from control. Conclusion: addition of nanoparticles in 1,2,4 % concentration of weight to acrylic based soft liner impaired the adhesion properties of Candida Albicans, and reduce fungal induced denture stomatitis.

Abstract: Aims: This study aims to evaluate the combined efficacy of aqueous extracts of propolis and Fluoridated Casein Phosphopeptide–Amorphous Calcium Phosphate (CPP.ACPF) paste or Minimal Intervention (MI) paste plus on improving enamel surface roughness after demineralization challenge. Materials and methods: A total of (75) posterior wisdom teeth were used in the study. Enamel blocks were prepared and divided into five groups randomly, the teeth in all groups were subjected to demineralization cycle and then treated with: Sinjar's aqueous extract of propolis (AEP)-MI paste plus cream n. (15), Sulaymaniah's AEP-MI paste plus cream n. (15), Duhok's AEP-MI paste plus cream group n. (15), control positive group of MI paste plus alone n. (15), and control negative group of artificial saliva alone n. (15). The Roughness of enamel blocks was measured using a profilometer machine at baseline, after demineralization cycle and finally after the treatment protocol.Results: There were statistically high significant differences among study groups after the demineralization cycle and there was an increase in surface roughness in all groups after demineralization, but the least elevation in surface roughness belonged to a mixture of Sulaymaniah's aqueous extract of propolis with MI past plus followed by Duhok's aqueous extract of propolis with MI past plus group after treatment protocol. Statistically, there were high significant reductions in surface roughness in all groups after the remineralization except in an artificial saliva group. Conclusions: Combination CPP-ACPF Paste with Aqueous Extracts of Propolis reducing enamel's roughness and increasingresistance to demineralization.

Abstract: Aims: To investigate the effect of in-office dental bleaching techniques on the microhardness of enamel and the influence of post bleaching diode laser irradiation on the surface microhardness of bleached enamel. Materials and methods: Forty bovine teeth were prepared and then randomly allocated into two equal groups (n=20) according to bleaching technique as follows: CB: Conventional in-office bleaching technique and LB: Laser–assisted in-office bleaching technique. Each group was subdivided into two subgroups (n=10) according to laser irradiation setting as follows: C2: Conventionally bleached followed by diode laser irradiation at 2-Watt laser, C4: Conventionally bleached followed by diode laser irradiation at 4-Watt laser, L2: laser –assisted bleached followed by diode laser irradiation at 2-Watt laser and L4: Laser–assisted bleached followed by diode laser irradiation at 4-Watt laser. Vickers microhardness was assessed three times for all the specimens: before bleaching, 24 hours after bleaching and finally 24 hours after post bleaching diode laser irradiation. Paired samples t- test and independent samples t- test were utilized for statistical analysis. Results: Both bleached groups exhibited a significant decrease in micro harness after bleaching with no statistically significant differences between them. Post bleaching diode laser irradiation at 2Watt and 4Watt resulted in significant increase in microhardness with no significant difference was evident between them. Conclusions: Diode laser irradiation on bleached enamel had a positive influence on surface microhardness of enamel and it may represent a promising post bleaching treatment modality.

Abstract:   Aims: This study aims to evaluate the effects of different storage temperatures -18°C, 5°C, 23°C and 40°C on degree of conversion of bulk fill composite. Materials and Methods: The tetric evoceram was randomly allocated into four equal treatment groups (n=10/group) according to the storage temperatures: A: 23°C (control), B: 5°C, C: -18°C and D: preheated to 40°C. After the material removal from storage. The forty-disc shape specimens were prepared with 8mm diameter and 4mm thickness all specimens cure with monowave LED light (LEDition light cure). After photoactivation, the specimens were stored in artificial saliva for 24 hours, at 37°C for complete polymerization.  The degree of conversion of the top and bottom surface of composite resin specimens were determined after 24 hours of curing using FTIR-ATR. Results: There was a significant difference in different storage temperatures on degree of conversion.  As the temperature of resin composite increase, the top and bottom degree of conversion of the specimens also increased. Conclusions: The degree of conversion of bulk-fill composite resin increase as the increase of pre-cure temperatures.

Abstract: Background: Interim or transitional restorations have been demonstrated as critical components in different dental treatments, they designed to enhance the esthetics, functions and protect the oral structures for limited period of time. Aims: This review focuses on several important aspects associated with the interim restorations including: materials, techniques of fabrication, and current trends in the application of interim restorations in fixed prosthodontics. Conclusions: Interim fixed restorations play a specific role in the diagnosis and treatment plan of the dental procedures. They must resemble the function and form of the definite prostheses. Therefore, interim restorations should satisfy the criteria of longevity, marginal adaptation and strength.