アブストラクト（35巻1号：The Bulletin of Kanagawa Dental College）

The Bulletin of Kanagawa Dental College

English

Title　： Effect of Abutment Design on Screw Loosening in Wide Diameter Implants
Subtitle　： ORIGINAL ARTICLES
Authors　： D.Vo, K.T.Ochiai, E.Sultan, S.Hojo*, A.A.Caputo
Authors（kana）　：
Organization　： UCLA School of Dentistry Department of Biomaterial, *Department of Oral and Maxillofacial Rehabilitation, Kanagawa Dental College
Journal　： The Bulletin of Kanagawa Dental College
Volume　： 35
Number　： 1
Page　： 3-8
Year/Month　： 2007 / 3
Article　： Original article
Publisher　： Kanagawa Odontological Society
Abstract　： [Abstract] [Purpose]: The use of dental implants of various diameters and sizes has been suggested as a treatment option for implant placement into areas of reduced or limited vertical osseous height or width. The purpose of this investigation was to determine the resistance to screw loosening for three different external hexagon wide diameter implant abutment designs. [Method]: Three 5.5 diameter 10 mm long implant designs (WD Lifecore implants, WP Mk II Biocare, 3i Wide Diameter) were embedded in resin blocks. Crowns, incorporating 25° cuspal inclines, were cast to fit the appropriate non-segmented machined abutments. The corresponding gold abutment screws were tightened to 32 N-cm with a calibrated ITI torque driver. Prior to fatigue loading, the torques required to loosen the abutment screws were measured as baseline values. The individual crowns were subjected to simulated occlusal loadings of 6,000 cycles in both clockwise and counterclockwise directions. The reverse torques required to loosen the screws were then measured. Each implant type and load direction was replicated five times. Comparisons among implants and load directions were analyzed using ANOVA and t-tests with corrections for multiple comparisons. [Results]: Upon counterclockwise cyclic loading, the retaining screw removal torque values were lower than the clockwise loaded torque removal values. Both the baseline and counterclockwise loaded screw loosening values were higher for the Lifecore than for the Biocare and 3i implants. The Lifecore loosening torque value was 18.22 +- 1.06 N-cm, compared to 14.75 +- 1.62 and 14.58 +- 0.95 N-cm for the Biocare and 3i implants respectively. [Conclusions]: All implant designs tested with occlusal load clockwise loading exhibited greater resistance to screw removal torque. The Lifecore implant demonstrated a significantly higher resistance to screw removal than the 3i or Biocare implants after counterclockwise cyclic loading. The implant abutment design and the direction of the occlusal loading force influence the degree of screw tightness and loosening.
Practice　： Dentistry
Keywords　： Wide diameter implants, Abutment design of implant, External hexagon