Experimentally induced abutment strains in three types of
single-molar implant restorations
Wook-Jin Seong, DDS, MS,a Tom W.P. Korioth, B Od, Cir Dent, PhD,b and James S.
School of Dentistry, University of Minnesota, Minneapolis, Minn.
Statement of problem. The choice of single-molar implant design is difficult 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 a 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 the buccal, lingual, mesial, and distal surfaces. Effects of implant design, load location, direction,
and magnitude were tested on axial and bending (buccolingual and mesiodistal) strains of 3 singlemolar
implant designs: (1) single, 3.75-mm (regular) diameter implant, (2) single, 5-mm (wide) diameter
implant, and (3) two 3.75-mm diameter (double) implants connected through a single-molar crown. Results
were analyzed with ANOVA.
Results. Variations in loading conditions induced 3-dimensionally complex abutment strains on the tested
implant designs. Peak absolute strains in mesiodistal direction were 6493 ∑ for design 1 and 3958 ∑ on
design 2, and 3160 ∑ in buccolingual direction on design 3. For all loading conditions, the single 3.75-mm
diameter implant consistently experienced the largest strains compared with wide-diameter and double implant
designs. Changes in centric contact location affected implant abutment strains 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. (J Prosthet Dent 2000;84:318-26.)