Osseointegration of dental implants without primary stability: an experimental study in sheep
Background and objective: Primary implant stability is considered necessary for
achieving and maintaining osseointegration. This experimental study aimed to evaluate the
outcome of implants without primary stability, clinically and radiographically.
Methods: Two adult sheep (3-4 years of age), 70 kg in weight, were included in the study.
After sedation and local anesthesia, the lateral side of the basal bone of mandible is
exposed by a single long incision. The implant bed performed in the inferior border of the
basal bone of mandible drilling to 5 mm in diameter and 10 mm in length. Five implants
were inserted into the basal bone of mandible for each side (right and left), but the sizes of
inserted implant was 3.8 mm in diameter and 10 mm in length, after 4 months the 2 sheep
were sacrificed and the universal torque ratchet was used to measure the stability of the
implant by a counter torque 30 N/cm test. Cone Beam Tomography (CBCT) was used to
evaluate the implants radiographically.
Results: Nineteen (from 20) implants successfully tolerated a 30 N/cm countertorque test
comprising (95%). Only one implant failed to osseointegrate (5%). During the healing
period, no any adverse clinical signs reported.
Conclusion: Dental implants may have a chance to osseointegrate even in the lack of
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