Objectives:The aim of this study was to assess the effects of different resin-based and ceramic superstructure materials and two different abutment types on the stress distribution of the abutment screw using the method of three-dimensional finite element stress analysis. Materials and Methods:A three-dimensional implant, abutment (zirconia and titanium), abutment screw, crown (zirconia reinforced lithium silicate, lithium disilicate, polymer-infiltrated resin ceramic, and PEEK), and alveolar bone were designed using Rhinoceros 3D modeling software and VRMesh Studio software to form 8 simulations. On the models prepared, loading was made on the lingual tubercle of the maxillary right first premolar crown at an angle of 30° with 150 N force obliquely in the buccolingual direction. The von Mises stress values obtained from the abutment screw were compared according to the types of abutment and crown materials. Results:The von Mises stress values in the abutment screw were higher in the models using a titanium abutment (on average 1336.24 MPa), and the lower stress values were obtained in the models using a zirconia abutment (on average 964.26 MPa). When the prosthetic material used was changed, the stress values on the abutment screw was similar.Conclusions: Considering that the abutment screw is the weakest component of the implant-system, zirconia abutments can be used reliably in the maxillary first premolar region where aesthetic expectations are high.
PurposeTo evaluate the effect of restorative materials with or without resin content, modeled on zirconia and titanium abutment materials, on the stress distribution on the alveolar bone, implant, and prosthetic crowns with a 3D finite element stress analysis.Material and MethodsTitanium and zirconia abutments were combined with three implant‐supported crown materials (polymer infiltrated hybrid ceramic (PICN), lithium disilicate (LD), and zirconia‐reinforced lithium silicate (ZLS)) to create six experimental groups. The 40 × 30 × 20 mm alveolar bone, 3.75 × 10 mm implant, esthetic abutment, and maxillary first premolar crown bonded over the abutment were the components of the finite element models. On the lingual cusp of the crown, the 150 N occlusal loading was applied in the buccolingual direction at a 30° angle. Equivalent von Mises stress and maximum and minimum principal stresses were used for both the qualitative and quantitative evaluation of the stress distribution of the created models.ResultsThe von Mises stress in implant and abutment did not differ according to the crown materials. The use of a zirconia abutment resulted in higher von Mises stress values in the abutment but lower stress values in the implant. The highest stress values were obtained in ZLS (196.65 MPa) and LD (194.05 MPa) crowns. The use of titanium abutments, regardless of crown materials, resulted in higher von Mises stress values in restorative crowns than in zirconia abutments. The principal stress values in alveolar bone showed similar distribution and concentration in all models.ConclusionsChanges in crown material did not affect stress distribution in the implant and peripheral bone. However, the zirconia esthetic abutment resulted in a lower stress concentration on the implant.
The aim of this study was to assess the knowledge and apprehension of patients at Afyonkarahisar Health Sciences University Faculty of Dentistry, about coronavirus disease-2019 . Material and Methods: The cross-sectional survey study consisted of 43 questions and three sections. These sections included questions about demographic information and general awareness and the source of awareness, the knowledge level about COVID-19, and apprehensions about dentist appointments and patients' knowledge about infection control. A total of 200 patients, who were randomly selected and agreed to answer the questionnaire, participated in the questionnaire survey. Chi-square analysis was conducted to analyze the statistically significant difference between patients' responses and independent variables such as sex and educational level. Statistical significance was set at p<0.05. Results: Of the participants, 98% thought that they had knowledge about COVID-19. One hundred thirty six participants (68%) indicated television as the source of information. The majority of the participants (82.5%) had excellent and good knowledge. There was no significant difference between the knowledge level and sex (p>0.05). However, a significant difference was found between age, educational status, and knowledge level (p<0.05). When concerns about COVID-19 transmission were evaluated, 122 subjects (61%) stated that they took some precautions during their visits to dental clinics. Conclusion: Most of the patients had heard of COVID-19 and were aware of infection control measures. However, some patients were worried about undergoing dental treatment due to COVID-19. Further steps should be taken to inform patients about COVID-19 transmission and infection control measures in a dental hospital.
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