Stress dissipation characteristics of four implant thread designs evaluated by 3D finite element modeling / 대한치과보철학회지

PURPOSE: The aim was to investigate the effect of implant thread designs on the stress dissipation of the implant. MATERIALS AND METHODS: The threads evaluated in this study included the V-shaped, buttress, reverse buttress, and square-shaped threads, which were of the same size (depth). Building four different implant/bone complexes each consisting of an implant with one of the 4 different threads on its cylindrical body (4.1 mm x 10 mm), a force of 100 N was applied onto the top of implant abutment at 30degrees with the implant axis. In order to simulate different osseointegration stages at the implant/bone interfaces, a nonlinear contact condition was used to simulate immature osseointegration and a bonding condition for mature osseointegration states. RESULTS: Stress distribution pattern around the implant differed depending on the osseointegration states. Stress levels as well as the differences in the stress between the analysis models (with different threads) were higher in the case of the immature osseointegration state. Both the stress levels and the differences between analysis models became lower at the completely osseointegrated state. Stress dissipation characteristics of the V-shape thread was in the middle of the four threads in both the immature and mature states of osseointegration. These results indicated that implant thread design may have biomechanical impact on the implant bed bone until the osseointegration process has been finished. CONCLUSION: The stress dissipation characteristics of V-shape thread was in the middle of the four threads in both the immature and mature states of osseointegration.

A Clinicostatistical Analysis Of Oral And Maxillofacial Infected Patients

A case of oral leiomyoma

Leiomyoma is a benign smooth muscle tumor that usually arise in the uterus, skin and gastrointestinal system. Only 2 percent are located in the head and neck. Leiomyomas of oral cavity are uncommon as only two cases have been reported in the Korean literature. The common location of oral cavity has been tongue, but other sites include buccal mucosa, lips, palate. mouth floor, and gingiva. Our patient was 30 years old female who complained of swelling and discomfort in the mouth floor. Microscopically this tumor showed bundles of intertwining spindle cells within fibrous connective tissue stroma. The nuclei were generally pale staining and blunt ended. Masson's trichrome stain was positive for muscle, and immunohistochemical study for alpha -smooth muscle actin revealed strong positivity. It was treated by surgical excision. We experienced a case of leiomyoma of oral cavity, so we report with literature reviews