The influence of abutment angulation on strains and stresses along the implant/bone interface: comparison between two experimental techniques.
BACKGROUND
Preangled abutments produce different stress distribution compared to straight abutments.


OBJECTIVE
The objectives of this study were to (1) test the hypothesis that preangled abutments produce different stress distribution than straight abutments by using strain gauges attached to implants embedded in a medium simulating bone to determine strain distribution along the implant/bone interface; (2) test this hypothesis by photoelastic method; and (3) compare the two experimental techniques.


METHODS
Five Integral Omniloc cylindrical implants 13 x 4 mm were polished to remove the hydroxyapatite coating, then six linear miniature strain gauges were attached, three on each side of the implant's surface. Two similar implants were embedded in a photoelastic material. Three abutments, straight, 15 degrees, and 25 degrees, were connected to each implant; strain versus applied compressive forces were recorded. Strain response to force parameter was defined as the slope of the strain-force curve. Isochromatic fringe patterns were also recorded.


RESULTS
The strain gauge measurements showed higher, threefold and 4.4-fold, compressive strain concentration in the coronal zone of the implant when 15-degree and 25-degree angulated abutments were used, respectively, compared with the straight abutment; whereas the photoelastic method showed an increase of only 11% in fringe order. Tensile strains were also measured from the coronal contralateral position on the implant, where photoelastic models did not show a change in stress type.


CONCLUSIONS
Data obtained from strain gauges bonded to implants embedded in a medium can represent a precise simulation of the clinical condition when analyzing stress distribution along the implant/ bone interface. Photoelasticity provides different information and therefore should be regarded as a complementary method.
Brosh
T
T
Department of Oral Rehabilitation, Maurice and Gabriela Goldschleger, School of Dental Medicine, Tel Aviv University, Israel.
Pilo
R
R
Sudai
D
D
D000704:Analysis of Variance; D001718:Birefringence; D019245:Compressive Strength; D000044:Dental Abutments; D003758:Dental Implantation, Endosseous; D015921:Dental Implants; D017267:Dental Prosthesis Design; D003799:Dental Stress Analysis / Q000295:instrumentation / Q000379:methods; D004548:Elasticity; D006801:Humans; D008961:Models, Structural; D013718:Tensile Strength
D015921:Dental Implants