Biologic response of immediately versus delayed loaded implants supporting ill-fitting prostheses: an animal study.
BACKGROUND
Computer-assisted preoperative implant planning and transfer toward the patient allow the production of a prosthesis prior to surgery. This implies that the prosthesis can be installed immediately following implant insertion. An inherent disadvantage of this is a cumulated error, which can lead to prosthesis misfit owing to topographic deviations of the planned versus the installed implants.


OBJECTIVE
The aim of this study was to determine whether prosthesis misfit is compromising the osseointegration of immediately versus delayed loaded implants and whether freshly installed implants adapt to the prosthesis.


METHODS
In each of five New Zealand White rabbits, two experimental conditions were compared. One tibia harbored the so-called test implant, which originally showed a vertical misfit of about 500 microm with the prosthesis to which it was tightened immediately after implant installation. The control implant was installed in the other tibia and was allowed to heal during 9 weeks before the prosthesis with the vertical misfit of about 500 microm was connected to it. The prostheses were left in place for 12 weeks, after which the animals were sacrificed.


RESULTS
All implants healed uneventfully. There were no statistically significant differences between the biologic responses of test and control implants. With a three-dimensional laser scanner, significantly more displacement of the test implants toward the prostheses was observed compared with the control implants. This led to a significant decrease in prosthesis misfit for the test implants compared with the control implants.


CONCLUSIONS
This study indicates that prosthesis misfit does not per se lead to biologic failure of immediately loaded or of already osseointegrated implants. In addition, immediately loaded implants seem to topographically adapt to the prosthesis, thereby minimizing the existing misfit.
Duyck
Joke
J
Department of Prosthetic Dentistry, BIOMAT Research Group, Katholieke Universiteit Leuven, Leuven, Belgium. Joke.Duyck@uz.kuleuven.ac.be
Vrielinck
Luc
L
Lambrichts
Ivo
I
Abe
Yasuhiko
Y
Schepers
Serge
S
Politis
Constantin
C
Naert
Ignace
I
D016301:Alveolar Bone Loss / Q000209:etiology; D000818:Animals; D003758:Dental Implantation, Endosseous / Q000379:methods*; D015921:Dental Implants; D017268:Dental Prosthesis Retention; D019094:Dental Prosthesis, Implant-Supported / Q000009:adverse effects*; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D005260:Female; D020007:Implants, Experimental; D007834:Lasers; D016348:Osseointegration; D017755:Prosthesis Fitting; D011817:Rabbits; D025321:Surgery, Computer-Assisted; D013977:Tibia; D013997:Time Factors; D014732:Vibration
D015921:Dental Implants