An ideal occlusal scheme plays an important role in a good prognosis of All-on-Four applications, as it does for other implant therapies, due to the potential impact of occlusal loads on implant prosthetic components. The aim of the present three-dimensional (3D) finite element analysis (FEA) study was to investigate the stresses on abutments, screws and prostheses that are generated by occlusal loads via different occlusal schemes in the All-on-Four concept. Three-dimensional models of the maxilla, mandible, implants, implant substructures and prostheses were designed according to the All-on-Four concept. Forces were applied from the occlusal contact points formed in maximum intercuspation and eccentric movements in canine guidance occlusion (CGO), group function occlusion (GFO) and lingualized occlusion (LO). The von Mises stress values for abutment and screws and deformation values for prostheses were obtained and results were evaluated comparatively. It was observed that the stresses on screws and abutments were more evenly distributed in GFO. Maximum deformation values for prosthesis were observed in the CFO model for lateral movement both in the maxilla and mandible. Within the limits of the present study, GFO may be suggested to reduce stresses on screws, abutments and prostheses in the All-on-Four concept.

BackgroundThe follow‐up of the peri‐implant marginal bone loss is the most important criterion for the determination of implant success.PurposeThe purpose of this study is to measure marginal bone loss using panoramic radiographic images (PRI) of patients treated using a mandibular, two implant–supported, locator‐retained denture and to evaluate the compatibility of these findings with those of the finite element analysis (FEA).Materials and MethodsThe PRI of patients who had a mandibular, two implant–supported, locator‐retained denture were assessed, and the mesial and distal marginal bone loss of both right‐ and left‐sided implants was measured. Mandibular and maxillary models, which have the features of bilateral balanced occlusion, were created. The surfaces of the generated models were converted in a computer‐aided design model that could be transferred to the FEA software, and the forces were defined on contacts formed in maximum intercuspation, lateral, and protrusive movement position for bilateral balanced occlusion.ResultsThe bone loss in the mesial and distal regions at the right‐ and left‐sided implants was not statistically significant. Higher stresses were formed on the vestibular side under protrusive movement, on the lingual side under maximum intercuspation, on the distolingual side under left unilateral biting, and on the mesiolingual side under right unilateral biting in the FEA.ConclusionAccording to FEA, peri‐implant bone resorption may be higher in the buccal and palatal regions, implying that panoramic radiographs can be misleading in understanding the amount of peri‐implant bone resorption.

No abstract

The objective of the present study was to evaluate condylar, ramal and condylar+ramal mandibular vertical asymmetry in a group of patients with different vertical skeletal patterns. Methods: Mandibular condylar and ramal measurements of 104 patients were performed on panoramic radiographic images and asymmetry indices were obtained according to the Habets' formula. The study groups consisted of 35 hypodivergent, 34 normodivergent and 35 hyperdivergent patients. Data were statistically analysed by means of two-way ANOVA, Kruskal-Wallis and Pearson chi square tests. Results: Ramal height was significantly higher in the hypodivergent group (p < 0.05). No significant differences were found between the vertical skeletal pattern groups in relation to the asymmetry indices (p > 0.05). Conclusion:Condylar asymmetry values were found to be higher than a 3% threshold value in all groups, but no significant differences were observed between the groups. The effect of the vertical skeletal pattern on vertical mandibular asymmetry was found to be insignificant.

Bu çalışmada yazarlar, klinik uygulama yapan diş hekimliği fakültesi öğrencilerinin koronavirüs hastalığı-2019 (COVID-19) enfeksiyonu ile ilgili bilgi düzeylerini, tutumlarını ve kaygı kaynaklarını incelemeyi ve değerlendirmeyi amaçlamaktadır.Objective: This study aimed to examine and evaluate the knowledge levels, attitudes and anxiety sources regarding coronavirus disease-2019 (COVID-19) infection in dentistry students in clinical practice. Materials and Methods: Fourth-and fifth-year dentistry students of Aydın Adnan Menderes University and Akdeniz University were selected for this study. For data collection, a questionnaire survey was performed. The questionnaire contained 34 items on demographic data, knowledge level about COVID-19 infection and attitudes and anxiety sources about their education. Descriptive statistical methods and the Pearson chi-square test were used to analyse data. P<0.05 was statistically significant. Results: A total of 137 students, including 75 females (54.7%) and 62 males (45.3%), participated in the study. Significantly higher levels of negativity and anxiety due to COVID-19 was found in female participants than in male participants, based on their responses to the following questions: "Do you believe that the lack of face-toface training due to COVID-19 will negatively affect your working life?"; "Do you worry about graduating having completed clinical practice without direct patient care?"; "Do you worry about practising your job because of the coronavirus?" and the p values were found 0.019, 0.002 and 0.009, respectively. The answers for these questions were not related to the graduation degree. Conclusion:The results reveal that female students demonstrated higher stress levels than male students based on the responses to some questions. Moreover, responses to the same questions were not related to the graduation degree. Further larger studies will give more accurate outcomes.