Morphological Aspect and iNOS and Bax Expression Modification in Bone Tissue Around Dental Implants Positioned Using Piezoelectric Bone Surgery Versus Conventional Drill Technique

Background: The aim of this work is to evaluate differences occurring in bone tissue around dental implants positioned using piezoelectric or conventional drill technique. Methods: Twenty-four implants were inserted bilaterally in the iliac crest of 6 sheep after site preparation through a piezoelectric instrument (Test) or after site preparation through conventional drill technique with rotary instruments (Control). Animals were randomly divided to be euthanized at 15 and 30 days post-intervention (p. i.); peri-implant bone samples were withdrawn and processed for histological analysis and immunohistochemical evaluation of iNOS and Bax expression. Results: Active remodeling phenomena in both Test and Control samples are showed at 15 days p. i., while at 30 days p. i., the overall organization of the peri-implant bone resembles native bone tissue. Immunohistochemical evaluation reveals a statistically significant increase of both iNOS and Bax expression at 15 days p. i. compared to samples obtained 30 days p. i. and to native bone. At both healing times, a higher but not statistically significant iNOS and Bax expression is recorded in samples from Control compared to Test Group. Conclusion: Even if the insertion protocol does not seem to significantly interfere with the long-term healing process, implant site preparation through the piezoelectric bone surgery technique may allow a reduction of peri-implant bone tissue inflammation and support a more rapid bone tissue healing phase.