Muhamed Ajanović

Analysis of the Abfraction Lesions Formation Mechanism by the Finite Element Method

Introduction: An abfraction lesion is a type of a non-carious cervical lesion (NCCL) that represents a sharp defect on the cervical part of tooth, caused by occlusal biomechanical forces. The largest prevalence of the NCCL is found on the mandibular first premolar. The goal of the study is, by means of a numerical method – the finite element method (FEM), in an appropriate computer program, conduct a stress analysis of the mandibular premolar under various static loads, with a special reference to the biomechanics of cervical tooth region. Material and methods: A three-dimensional model of the mandibular premolar is gained from a µCT x-ray image. By using the FEM, straining of the enamel, dentin, peridontal ligament and alveolar bone under axial and paraxial forces of 200 [N] is analyzed. The following software were used in the analysis: CT images processing–CTAn program and FEM analysis–AnsysWorkbench 14.0. Results: According to results obtained through the FEM method, the calculated stress is higher with eccentric forces within all tested tooth tissue. The occlusal load leads to a significant stress in the cervical tooth area, especially in the sub-superficial layer of the enamel (over 50 MPa). The measured stress in the peridontal ligament is approximately three times higher under paraxial load with regard to the axial load, while stress calculated in the alveolar bone under paraxial load is almost ten times higher with regard to the axial load. The highest stress values were calculated in the cervical part of the alveoli, where bone resorption is most commonly seen. Conclusion: Action of occlusal forces, especially paraxial ones, leads to significant stress in the cervical part of tooth. The stress values in the cervical sub-superficial enamel layer are almost 5 times higher in relation to the superficial enamel, which additionally confirms complexity of biomechanical processes in the creation of abfraction lesions.

Comparing the Retention of Cast Posts Cemented with Three Different Kinds of Cement

Objective: To check and compare the retenti on of cast posts cemented with three diff erent kinds of cement. Method: Forty fi ve 45 human permanent maxillary...

Assessment of Patient's Satisfaction with the Partial Removable Denture Therapy

Objective: The aim of this study was to assess patients satisfaction with retention, aesthetics, chewing, speech and comfort of wearing removable partial de...

Evaluation of Dental Fear and Anxiety in Displaced Persons in Bosnia and Herzegovina

Introduction In Bosnia and Herzegovina, apart from domicile population, there is a certain number of displaced persons. Most of them are situated in the area of Canton Tuzla. These persons are generally at risk of and being watched for various diseases, including the disease of the orofacial area. Dental fear and anxiety (DFA) is also inevitably present in displaced persons, with higher prevalence compared with general population. Therefore, the aim was to evaluate the DFA presence and the most common reasons for dental fear and anxiety in displaced persons in our country. Patients and methods 310 interviewed persons were included in this study, aged 35 to 44 years, from several cities of Canton Tuzla. They were divided in the group of displaced persons (n=153), and the group of domicile inhabitants (n=157). The study participants were interviewed about the DFA presence, as well as about the risk factors for DFA, which was subsequently evaluated by the Modified Corahs Dental Anxiety Scale. Results A high prevalence of DFA presence was determined in the total sample (38.71%), and particularly in the displaced persons group (57.52%). The results showed that displaced persons rarely visited dentists, mainly when it was necessary (odontalgia), with stronger reactions to factors that could cause DFA appearance. Conclusion Displaced persons are regarded as one of the highest risk groups for prevalence of DFA. This could be mainly due to poor oral health status, rare dental office visits and the urgent need for dental treatment, which could lead to vicious circle of mutual strengthening between bad oral health and DFA appearance.

Evaluation of the water sorption of luting cements in different solutions

OBJECTIVE To evaluate and compare the water sorption of three luting cements in three different solutions: distilled water and artificial saliva with different pH values (7.4 and 3.0). MATERIALS AND METHODS Resin-modified glass-ionomer cement (GC Fuji Plus) and two resin cements (Multilink Automix and Variolink II) were used. A total of 45 specimens - 15 specimens (15x1 mm) for each cement were prepared according to ISO standard 4049:2009. The water sorptions of the cements were calculated by weighing the specimens before and after immersion and desiccation. RESULTS . Nonparametric statistic methods were applied. GC Fuji Plus cement showed significantly higher values of water sorption in all three solutions of both resin cements (p<0.009) and significantly higher values of sorption in artificial saliva pH 3.0. Multilink Automix showed significantly higher values of water sorption compared with Variolink II in artificial saliva pH 7.4, and higher values of sorption in this solution compared with pH value 3.0. CONCLUSION Water sorption values are mainly influenced by the proportion of hydrophilic matrix, the type and composition of filler, and the pH value of solutions.

Biomechanics of cervical tooth region and noncarious cervical lesions of different morphology; three-dimensional finite element analysis.

Objective: The present study aims to investigate the influence of presence and shape of cervical lesions on biomechanical behavior of mandibular first premolar, subjected to two types of occlusal loading using three-dimensional (3D) finite element method (FEM). Materials and Methods: 3D models of the mandibular premolar are created from a micro computed tomography X-ray image: model of sound mandibular premolar, model with the wedge-shaped cervical lesion (V lesion), and model with saucer-shaped cervical lesion (U lesion). By FEM, straining of the tooth tissues under functional and nonfunctional occlusal loading of 200 (N) is analyzed. For the analysis, the following software was used: CTAn program 1.10 and ANSYS Workbench (version 14.0). The results are presented in von Mises stress. Results: Values of calculated stress in all tooth structures are higher under nonfunctional occlusal loading, while the functional loading is resulted in homogeneous stress distribution. Nonfunctional load in the cervical area of sound tooth model as well as in the sub-superficial layer of the enamel resulted with a significant stress (over 50 [MPa]). The highest stress concentration on models with lesions is noticed on the apex of the V-shaped lesion, while stress in saucer U lesion is significantly lower and distributed over wider area. Conclusion: The type of the occlusal teeth loading has the biggest influence on cervical stress intensity. Geometric shape of the existing lesion is very important in the distribution of internal stress. Compared to the U-shaped lesions, V-shaped lesions show significantly higher stress concentrations under load. Exposure to stress would lead to its progression.

Radiographic Evaluation of Crestal Bone Loss Around Dental Implants in Maxilla and Mandible: One Year Prospective Clinical Study

PURPOSE The aim of the study was to analyze the amount of maxillary and mandibular crestal bone loss around Bredent Sky Blue type of implants of different dimensions one year after implantation. MATERIALS AND METHODS 36 implants of diameter 3.5 x 10 mm were inserted in the maxilla and 12 in the mandible. 52 implants of diameter 4.0 x 8 mm were inserted in the maxilla, and 61 in the mandible (two-stage implant surgery). RESULTS No statistically significant differences were found between the right and left side of the maxilla and between the right and left side of the mandible at the implant sites regarding distal and mesial bone losses as shown by analysis of variance (ANOVA). CONCLUSION Statistically significant differences were found between anterior maxilla, posterior maxilla and anterior mandible and posterior mandible at implant sites regarding distal and mesial bone losses as shown by analysis of variance (ANOVA).

Measurements of Implant Stability Following Sinus Lift: A Pilot Clinical Study

AIM The aim of this study was to evaluate the implant stability of Bredent Sky Blue implants of different diameters following one stage sinus lift procedure. MATERIAL AND METHODS This study included 9 male patients with an existing indication for unilateral or bilateral sinus lift procedure. As grafting materials, combination of allograft material MinerOss® cortical & cancellous and Ossceram nano were used. RESULTS All implants were considered successful and ISQ levels were measured by Osstell ISQ device. The ISQ values were from 68 to 84. The mean values of stability of Bredent Sky Blue implants of different diameters following one stage sinus lift procedure were 77.73 ± 2.93 (MD) and 77.98 ± 2.72 (VO).

Effect of Three Topical Fluoride Solutions on Fluoride Level in Plaque

Objective: To examine process inside plaque after application of three topical fluoride solutions: 1% TiF4, 1% NaF and Aminfluorid soluti on. Efficiency of t...

Comparação da Retenção de Pinos Fundidos Cimentados com Três Tipos de Cimento

Objetivo: Verificar e comparar a retencao de pinos fundidos cimentados com tres diferentes tipos de cimento. Metodo: Quarenta e cinco incisivos superiores permanentes humanos foram divididos aleatoriamente em tres grupos de 15 dentes cada um. Os canais radiculares foram preparados para receberem pinos fundidos de ate 8.5 mm de comprimento. Os pinos foram cimentados com um dos tres tipos de cimentos a seguir: cimento de fosfato de zinco, cimento de ionomero de vidro e cimento de ionomero de vidro modificado por resina (hibrido). Apos a cimentacao, as amostras foram armazenadas em solucao salina durante 7 dias e entao submetidas a analise da forca de retencao em maquina universal de ensaios (Zwick num. 112627, Ulm-Germany). Resultados: O cimento hibrido apresentou o maior valor medio de retencao (312.90 N), seguido do cimento de ionomero de vidro (272.40 N) e do cimento de fosfato de zinco (312.90 N). A analise estatistica mostrou diferenca estatisticamente significante nos valores de retencao entre o cimento de fosfato de zinco e o cimento de ionomero de vidro (p<0,01), e entre o cimento de fosfato de zinco e o cimento hibrido (p<0,01). Conclusao: Nao houve discrepância significativa entre o cimento de ionomero de vidro e o cimento hibrido, embora a diferenca na forca de retencao entre os dois materiais tenha sido de aproximadamente 40 N.