Objectives: The objective this study is validate the use of nanoindentation tests in research and to assess the quality of newly formed bone in sheep mandibles submitted to Distraction osteogenesis (DO) and low-level laser therapy (LLLT) based on hardness and modulus of elasticity values. We also aim to determine the best moment for the application of laser therapy.

Methods: Extraoral distraction devices were placed in five sheep so as to achieve 1.5 cm of lengthened bone in 60 days. Distraction devices were removed 50, 40, and 33 days after surgery. Four animals were also treated with eight applications of infra-red laser (830 nm), in three equidistant spots (5 J cm ² and 50 mW) at different times. One was used as control (no laser therapy). The bone was submitted to nanoindentation tests for the assessment of hardness and modulus of elasticity and a computed tomography (CT) to bone contraction evaluation.

Results: When applied in the bone consolidation period, LLLT caused an increase in hardness and modulus of elasticity values. Animals irradiated with LLLT during the activation period presented lower values. CT revealed that the animals using the devices for 33 days presented contraction of the newly formed bone.

Conclusions: Nanoindentation tests were able to detect slight abnormalities in bone metabolism and proved to be important tools for the assessment of bone quality after DO. LLLT provides increased benefits when applied during the bone consolidation period. The bone consolidation period should be of at least 3 weeks, so as to prevent bone contraction.

Conflict of interest: None declared.