PURPOSEThe aim of this study was to evaluate the effect of cyclic loading and screw retightening on reverse torque value (RTV) in external and internal type implants.MATERIALS AND METHODSCement-retained abutments were connected with 30 Ncm torque to external and internal type implants. Experimental groups were classified according to implant connection type and retightening/loading protocol. In groups with no retightening, RTV was evaluated after cyclic loading for 100,000 cycles. In groups with retightening, RTV was measured after 3, 10, 100 cycles as well as every 20,000 cycles until 100,000 cycles of loading.RESULTSEvery group showed decreased RTV after cyclic loading. Before and after cyclic loading, external type implants had significantly higher RTVs than internal type implants. In external type implants, retightening did not affect the decrease in RTV. In contrast, retightening 5 times and retightening after 10 cycles of dynamic loading was effective for maintaining RTV in internal type implants.CONCLUSIONRetightening of screws is more effective in internal type implants than external type implants. Retightening of screws is recommended in the early stage of functional loading.
The presence of implant-prosthesis misfits can cause various complications. It is very important to detect misfits to prevent such complications. There are various evaluation methods for misfit assessment including clinical methods and laboratory in vitro methods. The clinical misfit evaluation includes radiographic analysis, visual observation, probing, Sheffield test, evaluation with disclosing materials, and screw resistance test. The laboratory in vitro evaluation method includes indirect modelling evaluation and direct metrological visualization. Of the indirect modelling methods, photoelastic stress analysis, finite element analysis, strain gauge analysis, and microbial colonization analysis were reviewed. Of the direct metrological visualization, microscopic analysis, 3-D photogrammetric analysis, coordinate measuring analysis, and radiographic analysis were reviewed. In this review, the characteristics, advantages and disadvantages of each method were evaluated.
Gangneung-Wonju National University, Gangneung, Republic of KoreaTeeth wear and extrusion of antagonist are commonly observed in deep bite patient having severe vertical and horizontal overlap. These problems cause collapse of occlusal plane and abnormal anterior guidance. Without restoring harmonious occlusion, loss of multiple teeth and decreased masticatory function could not be prevented. To resolve problems associated with deep bite, multidisciplinary treatment including oral surgical, orthodontic and prosthetic treatment should be performed. This clinical report describes the results of increasing occlusal vertical dimension with a full-mouth restoration procedure. The treatment procedures include extraoral and intraoral examination, diagnosis, treatment planning, diagnostic wax-up, segmental osteotomy, orthodontic intrusion and prosthodontic rehabilitation. Full mouth rehabilitation with increasing occlusal vertical dimension can solve esthetic and functional problems. (J Korean Acad Prosthodont 2015;53:26-38)
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