Load Transfer with Staggered Buccal-Lingual Implant Placement Including Wide-diameter Implants

Load Transfer with Staggered Buccal-Lingual Implant Placement Including Wide-diameter Implants
27 June 2003
H. ITOH1, A.A. CAPUTO2, T. SASAKI1, T. KUROE3, and H. NAKAHARA4, 1 Tohoku University, Sendai, Japan, 2 UCLA School of Dentistry, Los Angeles, USA, 3 Hokkaido University Graduate School of Dentistry, Sapporo, Japan, 4 Miyagi National Hospital, Japan
IADR
Objectives: Previous studies by the authors did not demonstrate a biomechanical advantage to a staggered 1.5 mm buccal and lingual offset placement of standard diameter implants. Questions arise as to potential load transfer advantages when wide diameter implants are included in the offset placement configuration. The purpose of this investigation was to compare photoelastically the stresses generated by a staggered implant configuration which included wide diameter implants. Methods: Two photoelastic models of an adult human left mandible edentulous distal to the canine were fabricated. Three screw type implants were embedded into the edentulous region of each model. Implants of 3.75 mm diameter and 13 mm long were placed (3i, Palm Beach Gardens, FL) in the premolar region, while 5 mm diameter 8.5 mm long implants were placed in the molar regions. The implants were placed in a straight line in one model and in a staggered 1.5 mm buccal and lingual offset configuration in the other. Fixed anchor bridges were fabricated to the same occlusal scheme for each placement configuration. Simulated vertical and lateral functional loads were applied to the prostheses at fixed locations. The stresses which developed in the supporting structure were observed and recorded photographically in the field of a circular polariscope. Results: Depending upon the load condition, some differences in stress distribution and intensity were noted between the straight line and staggered implant placement schemes. The highest stress levels occurred under cuspal loading for both placement configurations. Lingual cusp loads produced higher stresses with straight placement, while higher stresses resulted from buccal cusp loading with the staggered configuration. Conclusions: For the vertical and lateral loading conditions tested, there was no clear biomechanical advantage to staggered 1.5 mm buccal and lingual offset placement configuration. It is important that selection of placement configuration should include consideration of anticipated occlusion.