Low-level laser therapy improves peri-implant bone formation: resonance frequency, electron microscopy, and stereology findings in a rabbit model

Previous studies have reported positive effects of low-level laser therapy (LLLT) on bone healing. This study evaluated the effects of LLLT on peri-implant healing in vivo. Thirty-two rabbits had their mandibular left incisors removed, followed by immediate insertion of a dental implant into the fresh socket. Animals were assigned randomly to four groups: control (non-irradiated) or LLLT at three different doses per session: 5 J/cm2, 10 J/cm2, and 20 J/cm2. A GaAlAs laser (830 nm, 50 mW) was applied every 48 h for 13 days, starting immediately after surgery. The implant stability quotient (ISQ) was measured using resonance frequency analysis upon implant insertion and immediately after death, 30 days after the last application. Tissues were prepared for scanning electron microscopy (SEM) and stereology. Variables measured were bone–implant contact (BIC) and bone neoformation within implant threads at three different sites. The results showed better ISQ for the 20 J/cm2 group (P = 0.003). BIC values were significantly higher (P < 0.05) in the 20 J/cm2 group, on both SEM and stereology. Bone area values were better in the 10 J/cm2 (P = 0.036) and 20 J/cm2 (P = 0.016) groups compared to the control group. Under these conditions, LLLT enhanced peri-implant bone repair, improving stability, BIC, and bone neoformation. The findings support and suggest parameters for the design of clinical trials using LLLT after implant placement.