Agenor Osório¹, Roberto Rosendo Barros Reis², Suzimara Reis Gea Osorio¹, Adriana Neves Da Costa³, Karina Maria Salvatore Freitas^4,, Marcelo Cavenaghi Pereira Da Silva^{2, 5}

Midpalatine suture disjunction is a routine procedure in the orthodontic clinic; however, the cellular events involved in the procedure have not yet been completely explained. The aim of this study was to verify the tissue events, particularly those related to osteogenic differentiation, which occur in the region of the palatal suture after disjunction, by means of histologic and immunohistochemical analyses of the following noncollagenous proteins: BSP, OCC, OPN and ONC. In this study, 10 male Wistar rats aged two months and weighing approximately 250 g were used. The animals were divided into two groups of five animals: Group I – control (mini-implant placement) and group II – experimental (placement of mini-implant and disjunction spring made of 0.60mm steel wire, with an initial load of 2N (200 grams)). After 21 days, the animals were sacrificed and histological and immunohistochemical analyses were performed for the noncollagenous proteins. The use of the spring anchored to mini-implants promoted the disjunction of the median palatal suture, with a V-shaped opening, in which the base faced the superior region (at the nasal cavity) and the vertex was in the inferior region of the oral cavity (at the palatal bone). It could be concluded that after disjunction, there was presence of osteoblasts in an osteoid matrix in the region of the median palatal suture, and the immunohistochemical expression of the noncollagenous proteins increased in all the analyzed parameters, expression being most significant for ONC.

rapid maxillary expansion, anchorage, mini-implants, noncollagenous proteins