Stress analysis of incline implant supported fixed bridge at local area of maxillary molar

Objective To study the influence of incline implant supported fixed bridge at the local area of the maxillary molar on the implant-bone-interface stress distribution and illustrate the correlation between every influence factors about incline implant supported fixed bridge and late success rate of implant denture. Methods Three-dimensional finite element model for the insufficient vertical bone mass at the area of the maxillary molar was established biomechanically in this study by spiral CT technique and finite element software technique. Different experimental conditions were designed which were about different implant lengthes(7,9and 11mm,diameter of implants was 5.5mm and oblique angle was 10°),implant diameters(3.5,4.5and 5.5mm,length of implants was 7mm and oblique angle was 10°)and oblique angles of implant(5,10and 15°,diameter of implants was 5.5mm,length of implants was 7mm).The implant-bone-interface stress distribution was analyzed by 3-D finite element method under the action of vertical and decentralized load.Results When implant length changed from 7to 11mm,the stress of necks and root tips of implants was big,and the one on root tips was bigger than the necks at the same time.The stress on root tips was decreased as the length of the implant was increased and was closed to the necks.The feature on stress distribution of different diameters was that the stress of necks and root tips of implants was big with 3.5and 4.5mm in diameter,and the stress on each part of the implant-bone-interface was similar with 5.5mm in diameter.The feature of stress distribution on each part of the implant-bone-interface was very close in resemblance with different oblique angles,the stress of necks and root tips of implants was big. The stress of root tips of implants was increased as the angle was increased.Load distribution also affected stress distribution on the interface.The peak stress under a concentrated load was bigger than the one under decentralized load.Conclusion When the vertical bone mass at the local area of the maxillary molar is relative insufficient,the implant-bone interface stress distribution tends towards uniformity in selecting longer and wider-diameter implant. The complicated maxillary anatomical structure could be considered adequately to prevent stress concentration to occur in partial thick bone.