R. Mericskestern, FORCE DISTRIBUTION ON IMPLANTS SUPPORTING OVERDENTURES - THE EFFECT OF DISTAL BAR EXTENSIONS, Clinical oral implants research, 8(2), 1997, pp. 142-151
Citations number
15
Categorie Soggetti
Engineering, Biomedical","Dentistry,Oral Surgery & Medicine
Force distribution on mandibular implants supporting overdentures was
registered in vivo by means of piezo-electric transducers that allow f
or simultaneous force measurements in 3 dimensions. The anchorage devi
ce for connecting the overdenture to the implants was a U-shaped bar t
o which distal extensions were soldered bilaterally. Force patterns we
re analyzed under different test conditions such as maximum force when
biting in centric occlusion, maximum biting with the unilateral use o
f a bite plate, parafunction and chewing bread. Maximum force measured
in centric occlusion and on the ipsilateral implant with the use of b
ite plate was increased in the vertical dimension, compared to transve
rse dimensions. On the contralateral implant, equally low values were
found, in all 3 dimensions. Transverse force components reached 5 to 3
5% of the vertical magnitudes. With the use of the bite plate on the i
psilateral implant, force magnitudes in the vertical direction and in
the backward-forward direction were significantly higher (P<0.01, P<0.
00) compared to measurements in centric occlusion. Chewing and grindin
g resulted in lower vertical forces compared to maximum biting, while
transverse forces in the backward forward direction reached force magn
itudes that resembled the vertical component (50 to 100%). The prevale
nt (>95%) or exclusive force direction in the vertical dimension, regi
stered on both implants was downward. However, with the unilateral use
of the bite plate, upward directions were found on the contralateral
implant as an effect of distal bar extensions. This was in contrast to
previous results where upward force directions were not found. In tra
nsverse dimensions, the specific influence of bar extensions was recog
nised in backward directions on the contralateral implant. In comparis
on with previous results, it was concluded that, in vivo, the effect o
f distal bar extensions was of much lesser influence regarding force m
agnitudes and force directions than was expected.