Purpose: The aim of the present animal study was to examine the impact of two implant designs

that promote different insertion torque values on implant stability and evaluate, histomorphometrically,

the bone healing for immediate implant placement in fresh sockets.

Materials and Methods: Twelve female sheep (35.0±5.0kg) and 48 conical Morse-taper dental

implants divided into two groups (n = 24 per group): G1 group, where the implants present

a design that can provide high insertion torque values; and G2 group, where the implants

present a design that can provide low insertion torque values. Both had the same surface

treatment, and dimensions (4.0 mm in diameter and 10 mm in length). The first two posterior

teeth (both sides) were extracted carefully. Sequentially, there were osteotomies in the mesial

socket of each molar tooth. The final implant position was 2 mm below the buccal bone crest

level. On the right side, implants of the G1 were placed anteriorly, followed by implants of

the G2; and, on the left side, it was the reverse. A digital torquemeter was used to measure the

maximum final insertion torque value (f-IT). The initial implant stability quotient (ISQ) was

measured immediately after the implant insertion (T0) and immediately after the euthanasia

and removing the mandibles with the implants. The animals were euthanized (n=6 animals/

time) at 21 days (T1) and 35 days (T2). The t-test was used to compare statistical differences

for each intragroup parameter analyzed. Pearson's correlation was used to analyze possible

correlations: f-IT and BIC%, f-IT and ISQ, and ISQ and %BIC.

Results: Regarding the insertion torque, the G1 presented higher values than the G2, with a

statistically significant difference (p<0.0001). The ISQ mean values were higher in the B-L

direction than those obtained for M-D for both groups. %BIC measurements showed higher

values in samples from G2 than G1 at both times and in both directions. New bone, medullary

spaces, and collagen matrix had statistical differences between the groups at each evaluation

time.

Conclusion: Using implants with a modified macrogeometry plays a significant role in implant

stability and the healing process of bone tissue around the implant. It is important for

clinicians to carefully consider implant macrogeometry when planning dental implant surgery

to achieve optimal implant stability and successful osseointegration, mainly in cases of immediate

implant placement.