Sharif Digital Repository

Natural teeth are connected to alveolar bone by periodontal ligaments ( PDL). PDL in addition to supporting tooth have the damping effect on transferring load from tooth to the surrounding bone. The most common replacement for a complete tooth loss is the use of Osseointegrated dental implants. The healthy bone remodeling and full bonding between bone and titanium surface of the implant is subjected to a successful osseointegration. The lack of PDLs in the structure of implant-bone system could lead to the failure of implant’s components due to overloading or to the impact loads. The aim of this study is to use viscoelastic material in the structure of dental implants to compensate for the... 

In this research Ti-6Al-4V samples were surface treated with acid, alkali and sandblasting treatment. Alkali treatment parameter was the NaOH concentration. The results of roughness measurement demonstrate that increase in NaOH Concentration results in rougher surface. Sandblasting produces rough surfaces in the scale of 1 to 10 micrometers. Acid treatment reduces initial roughness and the resultant roughness is in the under micrometer scale. After surface treatment, samples were soaked in simulated body fluid for invitro assessment. Results of this analysis indicate that sample with sandblasting+chemical treatment has the best invitro bioactivity. Chemical+sandblasting treated sample shows... 

Due to the key role of implant stability and Oseointegration in dental implant success, in the last two decades, many methods have been proposed to assess these parameters. Resonance Frequency Analysis (RFA) is one of these methods that attracted special attention and has been widely used in implant stability assessment. In the present work, a method is proposed that uses fuzzy logic to solve RFA restriction in evaluating Oseointegration degree.
In the first part of this work, a 3-D finite element model of implant-bone system is used to study factors affecting system resonance frequency. Then, fuzzy logic is used to propose a method for evaluating degree of Oseointegration. The designed... 

Loosening of uncemented tibial component is one the most common causes of total knee prosthesis failure which is a result of short-term factors such as instability and incomplete osseointegration as well as long-term factors such as peri-prosthetic stress shielding and bone atrophy. Porous cellular structures for tibial stem have been considered as a solution to this problem. This project is aimed to achieve an optimal gradient porous cellular design of tibial stem that in addition to sufficient mechanical strength, provides a perfect osseointegration and prevents bone resorption by incorporating appropriate porosity size, small micro-motion and favorable stress distribution on bone. A... 

Flexible cones are one of the latest bone loss treatment methods in the ever-increasing revision total knee arthroplasty. This study is conducted to assess the biomechanical performance of the tibial flexible cellular cones in enhancing the initial stability of the implant system through the analysis of implant micromotion, as well as minimizing stress shielding through the analysis of strain distribution in the bone. The research evaluates the impact of various geometrical variables, including the thickness of the porous wall, the presence, type, width, number, and location of the inner solid wall notches on the spring stiffness and stress distribution of these cones. The research...