Are insertion torque and early osseointegration proportional? A histologic evaluation

Area of Science:

• Biomaterials Science
• Dental Implantology
• Histology

Background:

• Primary implant stability is crucial for osseointegration.
• Drilling protocols can influence initial bone-to-implant contact and subsequent healing.
• Understanding the impact of drilling dimensions on early biologic responses is essential for optimizing implant success.

Purpose of the Study:

• To evaluate the effect of three drilling protocols (oversized, intermediate, undersized) on biologic responses to a single implant type.
• To assess early healing periods (2 weeks) in a canine model.
• To correlate drilling dimensions with insertion torque, bone-to-implant contact (BIC), and bone area fraction occupied (BAFO).

Main Methods:

• Histologic study utilizing a beagle dog model.
• Three drilling dimensions (3.5mm, 3.75mm, 4.0mm) were used for Unitite implants (4mm x 10mm).
• Insertion torque, BIC, and BAFO were measured and statistically compared using the Wilcoxon signed-rank test with Bonferroni correction.

Main Results:

• Insertion torque increased significantly with decreasing drilling diameter (P = 0.005).
• Bone-to-implant contact (BIC) and bone area fraction occupied (BAFO) were highest in the recommended and undersized drilling conditions.
• The oversized drilling condition showed statistically significant reductions in BIC and BAFO (P < 0.01).

Conclusions:

• Reduced drilling dimensions enhance primary stability (insertion torque).
• Optimal drilling dimensions maximize bone integration (BIC and BAFO) at early healing stages.
• Oversized drilling negatively impacts early osseointegration, highlighting the importance of precise drilling protocols.