Low Intensity Thermal Stimulation to Enhance Early Osteointegration in Implants: A Preclinical Study in Rabbits

This study is the first to integrate 3D finite element modeling, in vitro validation, and preclinical animal experiments to determine the efficacy of low-intensity thermal stimulation (LITS) in enhancing dental implant osseointegration. The study seeks to provide experimental evidence for applying thermal stimulation as a possible approach to enhance osseointegration.

A 3D finite element implant-femur model and in vitro implant-bone system were developed to simulate heat distribution. LITS conditions (50°C/5 s) were validated to avoid exceeding the osteoblast safety threshold (47°C). Eighteen rabbits received femoral implants divided into: control (no heating), T1 (single 50°C/5 s heating cycle), and T2 (three cycles). Outcomes included implant stability (IST), reverse torque, bone volume fraction (BV/TV), and histomorphometric osseointegration rate at 6 weeks.

Finite element and in vitro analyses confirmed 50°C/5 s as the optimal protocol, maintaining implant surface temperatures ≤ 46.3°C and complete thermal recovery within 1 min. T1 significantly increased in vivo rabbit model reverse torque (p < 0.05) and BV/TV (p < 0.05), while T2 showed no BV/TV improvement. Both T1 and T2 exhibited higher osseointegration rates (p < 0.05). Implant stability (IST) remained unchanged across groups (p > 0.05).

LITS at 50°C/5 s safely enhances early osseointegration in rabbits, increasing biomechanical anchorage and peri-implant bone formation. This study provides preliminary experimental evidence for the potential of thermal application in enhancing implant osseointegration.