Experimentally induced abutment strains in three types of single-molar implant restorations

Statement of problem. The choice of single-molar implant design is difficul t because of a lack of controlled, quantitative biomechanical analyses. Purpose, This study determined the effect of 3 single-molar implant designs on implant strains under 3 variety of homologous loading conditions. Material and methods. On each implant abutment, 4 strain gauges were placed axially at 90 degrees to each other on Is buccal, lingual, mesial, and dis tal surfaces. Effects of implant design, load location, direction, and magn itude were tested on axial and bending (buccolingual and mesiodistal) strai ns of 3 single-molar implant designs: (1) single, 3.75-mm (regular) diamete r implant, (2) single, 5-mm (nide) diameter implant, and (3) two 3.75-mm di ameter (double) implants connected through a single-molar crown. Results we re analyzed with ANOVA. Results. Variations in lending conditions induced 3-dimensionally complex a butment strains on the tested implant designs. Peak absolute strains in mes iodistal direction were 6493 mu epsilon for design 1 and 3958 mu epsilon on design 2, and 3160 mu epsilon in buccolingual direction on design 3. For a ll loading conditions, the single 3.75-mm diameter implant consistently exp erienced the largest strains compared with wide-diameter and double implant designs. Changes in centric contact location affected implant abutment str ains differently among the 3 designs. Angulated force direction resulted in larger bending strains. Conclusion. For single-molar implant designs, an increase in implant number and diameter may effectively reduce experimental implant abutment strains.