Effect of Drilling Preparation on Immediately Loaded Implants: An In Vivo Study in Sheep.

This article investigates the biological and biomechanical effects of two dental implant drilling protocols—undersized preparation (US) and nonundersized preparation (NUS)—on cortical bone osseointegration under immediate loading conditions in a sheep model. Forty-eight implants were placed in sheep mandibles, with half subjected to dynamic vertical loads immediately after insertion, and outcomes such as insertion torque value (ITV), resonance frequency analysis (RFA), bone-to-implant contact (BIC), and new bone formation were assessed over five weeks. Results showed that the US protocol yielded significantly higher primary stability (ITV) and greater BIC compared to NUS, while immediate loading did not impair osseointegration; notably, loading induced intense new bone formation in the NUS group despite lower initial stability. The study concludes that immediate loading is advisable only when primary stability exceeds an ITV of 10 Ncm and an RFA value of 60, emphasizing the importance of implant stability and drilling technique in successful immediate implant loading.