Abstract: Aims: The aim of this study was to evaluate the effect of mixing different concentrations of chlorhexidine, iodine ,and sodium hypochlorite solutions on the setting time and dimensional change of alginate impression material. Materials and methods: Total number of samples (40) has been prepared in this study. Ten samples for control group made from pouring alginate impressions of metal model .The other groups made by mixing alginate with 0.05% iodine, 0.5% chlorhexidine and 0.5% sodium hypochlorite solutions. Dimensional change was measured with AutoCAD program .The Setting time was also measured for each group. Statistical analysis was performed using ANOVA and Duncan multiple range test. Results: no significant difference in the linear dimensional change among the tested groups ,sodium hypochlorite added to alginate as disinfectant showed the highest dimensional changes among the other groups. There was a significant difference among the tested groups in the setting time. It was found that treating the alginate with sodium hypochlorite and chlorhexidine disinfecting agents accelerated the setting time of the material. Conclusion: The testing disinfecting agents can be used safely regarding dimensional change.

Abstract: Aims: To compare between the effects of deproteinized bovine bone (DBB) and osteon in the healing of mandibular bone defects in the rabbits. Materials and Methods: This experimental study was conducted on ten rabbits at the Animal House, Dentistry college, Mosul University. The rabbits weighted between 1.5 and 2 kg and each rabbit was given anesthesia (10% ketamine (40 mg/kg) and 2% xylazine (5 mg/kg). Surgery was performed aseptically. Mandibles were exposed through a sub-mandibular incisions. Three rectangular full thickness defects (6×5 mm) were created in each side. The first defect in each side was filled with DBB, the second defect was filled with osteon, while the third defect was left untreated to serve as a control. Five rabbits were sacrificed after one week and the other five rabbits were sacrificed after one month. The bony mandibles were immersed in 10% formalin solution and examined histologically by two histopathologists. Results: Microscopically, sections for one week of all groups showed mild degree of inflammation, moderate amount of vascularity, granulation tissue and osteoid tissue formation. Sections of one month showed no difference regarding the degree of inflammation vascularity, but the amount of granulation tissue and osteoid tissue formation in the control group were lesser than the amount seen in both experimental groups. Conclusions: DBB and osteon accelerate bone healing after month regarding the amount of granulation tissue and osteoid tissue formation.

Abstract: Aims: The aim of this study was to evaluate the shear bond strength of brackets bonded to composite restorations using four types of surface conditioning procedure. Materials and Methods: Thirty two cylindrical cavities were made at the center of self-cured acrylic resin blocks. All cavities were then filled with composite resin. The specimens were randomly divided into four groups. Group one: Composite surface was acid etched with 37% phosphoric acid. Group two: After using 37% phosphoric acid, bonding agent was applied and cured. Group three: After using 37% phosphoric acid silane coupling agent was applied then bonding agent was applied. Group Four: The composite surface roughened with a diamond bur, and then 37% phosphoric acid was applied. Brackets were bonded onto the composite prepared samples with Transbond XT. Shear Bond Strength was measured by a universal testing machine. KruskalWallis test was utilized for data analysis. Results: There was a significant difference between the four groups. The highest bond strength was that of Group 3. Group 1 had the lowest bond strength. Conclusions: Roughening the composite surface before acid etching was effective to improve the bond strength of orthodontic brackets to composite restorations. Addition of silane before bonding agent application result in highest bond strength.

Abstract: Aims: the aim of this study is to determine a calibration factor to eliminate the distortion in the linear cephalometric measurements. Materials and Methods; the study was performed on the 5 dry skulls, the first skull contained 12 radiopaque markers fixed at different plains, and radiographed by digital cephalometric x-ray machine. The X and Y axes of the shadow of each radiopaque marker used to estimate the calibration factor. Eight linear distances measured directly and radiographically on the conventional cephalographs of the 5 skulls to evaluate the detected calibration factor. Results; the results showed no-significant difference (p > 0.05) between the direct and calibrated radiographic measurement on the digital and conventional cephalographs. whereas significant difference was found between the conventional cephalometric linear measurements as compared with direct anatomical linear and the conventional cephalometric linear measurements with those measurements manipulated with the estimated calibration factor (p < 0.05). Conclusions; this study found that the conventional cephalometric linear measurements could be reliable as that of digital cephalometric linear measurements, if it's calibrated by the calibration factor (1.08) which is estimated by the present study.

Abstract: Aims: Hepatitis B virus infection is a global health hazard. The virus can be transmitted by both parenteral and non- parenteral methods such as direct contact with mucus membrane. Dental instruments can be the source of infection, therefore this study was conducted to detect HBs Ag in dental instruments used in the different public dental centers and clinics in Duhok governorate. Sampling process was from December 2016 to January 2017. Materials and Methods: A total of 549 samples were collected from five different districts as follow: 238 samples from center of Duhok, 121 samples from Zakho, 87 samples from Amedi, 68 samples from Sumail and 35 samples from Aqre. Four different commonly used dental instruments were chose namely: Scaler tips, curette, sickle and chisele. The samples divided into sterilized and used using capital A letter for sterilized and small a letter for used samples. Results: No HBs Ag was detected in all tested samples both sterilized and non- sterilized samples by ELISA technique. The results of the present study indicated to the proper hygienic precautions implemented in public dental centers and clinics as well as to the effectiveness of anti-HBV vaccine that almost all dentists had been received prior working. Conclusions: Further studies are required to cover private dental instruments as well as dentists and assistant technicians using both ELISA and RT-PCR techniques.

Abstract: Aims: Orthodontic treatment is known as a painful procedure among patients. They feel varying degrees of pain during orthodontic treatment from the stage of initial examination till the end of the treatment. The aims of this study are to explore pain experience among patients undergoing orthodontic treatment with the fixed appliances by comparing two different arch wires sizes. Materials and Methods: The study group consisted of 60 patients (26 males, 34 females) with a mean age of 17.6 years and 20.5 years consequently. Insertion of either 0.014 or 0.016-inch wire was by random selection of patients. Patients were asked to fill out a series of questionnaires for five consecutive days after the insertion of orthodontic initial arch wire, and after the arch wire activation for 4 hours, 6 hours, 24 hours, and till 5 days. The intensity (weak, mild, moderate, severe, and intensive) of the pain symptoms in connection with ten items (Biting on a hard/soft food, sensitive to hot or cold food/drink, mastication of food, fitting anterior and fitting posterior teeth together, cheeks, lips, and tongue pain) have been evaluated. Results: No significant differences were found between age groups, and between the two arch wire groups. Pain perception was more significant in females than in males and the pain perceived at the anterior teeth was greater than posterior teeth. Pain percentage level increased gradually till reaching the peak within 24 hours after the insertion of arch wire and retained the same level in the 2nd day, then decreased till the 5th day. Perceptions of pain by fitting anterior teeth were exactly the same within the period of the first few hours in both arch wire groups, and decreased over the following hours. Conclusion: No age discrimination was found for perception of pain in the two different arch wire groups, with no significant correlation for the time with initial pain that perceived after the insertion of two different initial arch wire sizes then the intensity of pain reduced over the time. Pain was perceived as being greater at the anterior than the posterior teeth and females experienced more pain than males.

Abstract: Aims: The aims of the study are to evaluate the radiographical views, OPG and periapical views on the changes in peri- implant bony tissue around dental implant at time of placement and another reading after 16 weeks before functional prosthetic loading and regard it as a prognostic parameter. Material and methods: Nineteen cases with 24 implant were enrolled for standardization. Radiographical measurement undertaken by a periapical and OPG radiographs after implant placement, then after16 weeks later, again a second periapical and OPG radiographs were taken for measurements using Dimaxis 3.2.1. Software program to estimate marginal bone height of both sides of implant and its changes during times of evaluation. Results: 19 medically fit patients, male and female with age 22-65 years, twenty four implants with average bone loss 0.59 mm mesialy and 0.60 mm distally at T0 as standered base line in compared to 0.98mm mesialy and 1.11mm distally at T1as average bone loss. There was a significant bone resorption in both sides in relation of implant size and in comparison to time of placement and after 16 weeks according to statistical analysis. Conclusion: OPG and periapical views are a good parameter for evaluation of successful implant and monitoring of the prognosis and stability and durability, as these radiographs more available in most dental centers and clinics with less cost.

Abstract: Aims: prosthetic rehabilitation of a maxillary defect after hemi-maxillectomy with a palatal obturator made from nickel chromium framework. Materials and methods: A silicon impression was made and poured with a dental stone to develop a definitive cast. The site, position and shape of maxillary defect determine the path of insertion. Design the metal framework of the obturator to Class II R.P.D according to Kennedy's classification. Casting the framework in base-metal alloy made from nickel chromium framework, centric jaw relation was recorded. A finished prosthesis (an obturator of closed hollow-bulb type) was inserted. Conclusions: Obturator prosthesis enhancing function and speech, reduce the rate of fluids and food passing to the nose. Extend the border of an acrylic of the prosthesis at defect site lead to enhance both the retention and stability of the obturator.

Abstract: Aims: The present study tests the effect of preoperative encouraging words provided by dental clinician on the levels of anxiety and pain experienced by patients after tooth extraction. Materials and methods: Patients were randomly assigned to the intervention and the control group. Intervention subjects had pre-operative ten minutes appointment with operating oral surgeon. This appointment identify the sources of anxiety, and participants given individualized encouragement according to their needs. Control subjects received reassurance immediately before surgery. All patients completed several questionnaires covering measures of anxiety and pain. Results: Discussion with patients along with encouragement highly affects patients’ levels of anxiety and pain after tooth extraction. Conclusions: Dental clinicians should consider the practice of encouraging patients shortly before tooth extraction.

Abstract: Aims: to evaluate the accuracy of W angle, ANB angle and gonial angle in assessing anterio-posterior jaw dysplasia and the correlation between them in class I , II, III patients. Materials and Methods: one hundred twenty patients (18-30) years of male and female from the center of Mosul City that met the criteria of the sample with class I, II, and III, the sample was divided into 3 groups The: 40% was male (48 cases) and 60 % was female (72 cases). Three groups 40 cases were distributed for each one of class I, II, III. Cephalometric analysis and measurement of angles were done .Results: the mean value of gonial angle for class I was 126.24±0.77° , class II cases was 123.42±0.86° and the class III cases was 127.53±0.98°;the mean value of W angle for class I was 53.953±0.309° , for class II was 48.78±1.29° and for class III was 60.96±3.00; 3; the mean value of ANB angle for class I was 2.71±0.155° , class II was 5.82±0.431°and for the class III was -3.182±0.241.The comparison between all variables in all classes showed highly significant differences at p