for a nite group g the commutativity degree denote by d(g) and de nd: d(g) = jf(x; y)jx; y 2 g; xy = yxgj jgj2 : in [2] authors found commutativity degree for some groups,in this paper we nd commuta- tivity degree for a class of groups that have high nilpontencies.

objective: in all ceramic fixed partial dentures the connector area is a common fracture location. the survival time of three-unit fixed partial dentures may be improved by altering the connector design in regions of maximum tension. the purpose of this study was to determine the effect of buccolingual increase of the connector width on the stress distribution in posterior fixed partial denture...

o bjectives: headgears are among the effective orthodontic appliances to achieve treatment goals. unilateral molar distal movement is sometimes needed during an orthodontic treat- ment, which can be achieved by an asymmetric headgear. different unilateral headgears have been introduced. the main goal of this study was to analyze the force system of uni- lateral expanded outer bow asymmetric hea...

introduction: the fracture strength of endodontically treated teeth compared to vital ones has long been a source of controversy. it is not clear how root canal therapy affects the stress distribution in teeth. the purpose of this study was to evaluate the changes in stress distribution after root canal therapy in a human maxillary canine by finite element analysis (fem). materials and methods:...

introduction: excessive temperature rise during drilling of the mandible for dental implant placement might damage adjacent osseous tissues. various factors affect temperature rise, including the geometrical parameters of surgical drills, one of which is the drill bit head angle. the aim of this research was to determine suitable drill bit head angle to induce minimum temperature rise during ma...

introduction: with the rapid increase in use of lasers in medical treatments, it is important to understand the mechanisms of heat transfer in biological tissues in order to minimize damage to the tissues resulting from extra heat applied. the aim of this study is to investigate the temperature distribution in living biological tissues when laser irradiation is used in a treatment. methods:  in...

conclusions the most relevant finding was that hook pinning in pauwels type iii fracture may result in delayed :union: or non:union: due to significantly increased stress of a traction force at the fracture site that works to displace the fracture. however, in a pauwels type i fracture, increased compression stress contributes to stabilize it. surgeons are recommended not to treat pauwels type ...

background and aims. all-on-four technique involves the use of tilted implants to allow for shorter cantilevers. this finite element analysis aimed at investigating the amount and distribution of stress in maxillary bone surrounding the implants with all-on-four vs. frequently used method with six implants technique using different numbers and inclination angles. materials and methods. a 3d ede...

objective: intrusion as a type of tooth movement is managed by different mechanotherapies during various treatment stages. the morphology of the apical third of the teeth to be intruded plays an important role in the risk of root resorption due to the raise of stresses. the main goal of this study was to compare various types of apical third of the teeth while loaded by an intrusive force. mate...