World Dental Implants and Orthodontics Congress August 17-18, 2018 Tokyo, Japan

Soonshin Hwang completed her dental education at Creighton University School of Dentistry. She has completed the AEGD (Advanced Education in General Dentistry) program at Columbia University and orthodontic specialty training at Yonsei University Gangnam Severance Dental Hospital. She currently works at the Orthodontic Department of Gangnam Severance Dental Hospital as a clinical assistant professor.

The aim of this study was to investigate the alveolar bone width of lower incisors in skeletal Class III adults of different vertical facial patterns. CBCT images of 90 skeletal Class III patients were evaluated and 29 Class I patients were assigned as the control group. Class III subjects were divided by mandibular plane angle; high (SN-MP>38.0°), normal (30.0°

Material and Methods: In this randomized clinical trial 75 patients (48 females and 27 males) underwent mandibular molar extraction and socket preservation by using allograft bone in control group: allograft bone with collagen membrane in group 1 and allograft bone with the amniotic membrane in group 2. All 25 stages of socket preservation procedures in each group were done by the same surgeon and evaluated by the same radiographic machine. The data were statistically analyzed by SPSS software, one-way ANOVA and Tukey post-hoc tests. The P-value <0.05 was considered as significant. Results: The results of this study showed that after 4 months the mean density difference in the extracted site was 1736.88 in control group; for patients who underwent socket preservation with allograft and collagen membrane it was 1746.20 and in cases, with allograft in addition amniotic membrane it was 1762.48. Discussion and Conclusion: The results demonstrated that, compared with control group, both collagen membrane and amniotic membrane showed a higher mean bone density (P-Value =/998 and P-Value = /918), but this difference was not statistically significant. Whereas amniotic membrane showed a higher bone density than the collagen membrane, there are no significant differences between these two groups (P-Value =/994). Although socket preservation methods may be effective on alveolar bone contour stability, we cannot significantly confirm the efficacy of these methods on bone quality and density. Keywords: Amnion; Collagen; Ridge Augmentation; Bone Density

Aim: The present study aims at determining what maybe the causes of poor quality appliances and also find out what appliance has the highest failure rate. Methods: A survey consisting of 27 questions was distributed among orthodontist and orthodontic post grads in Saudi Arabia. Results: The most common appliance needing an adjustment was Hawley Retainer (52.6%) and the least common appliance needing an adjustment was Essex Retainer (47.4%). Respondents were asked which component of each appliance was most commonly responsible for an ill-fit. For Hawley and wrap-around retainers and spring aligners, clasps were the most common problem at (52.6%) and (45.1%) respectively. Limitations: Insufficient studies related to the subject. Less responses than expected which may be due to few number of orthodontists in Saudi Arabia and poor cooperation in participating the survey in relation to number of surveys distributed. Conclusion: Most of the orthodontists reassured the quality of the cases returned from the lab with visual inspection and accuracy of fit being the most practiced way. 10% of the appliances fail within the first six months whereas solder joint followed by cement loss at bands and acrylic were the three most common areas of failure. Key words: Failure, orthodontic appliances, quality assurance, impression.