Miniscrew design and bone response: Defining a correlation

Abstract

This prospective clinical trial aims at correlating miniscrew implant (MSI) micro/macro architecture, the method of placement, and biologic markers in peri-MSI crevicular fluid (PMICF) as indicators of bone response. A comparative evaluation of surface morphology of the MSIs before placement and after retrieval defines a correlation between the architecture of the MSIs and the bone- implant contact ratio. Two types of MSIs (hybrid and cylindric) were placed in ten patients using a split-mouth technique with the aid of a restricted random number table. Each of the MSIs was placed in the intraradicular area between the second premolar and first molar in the attached gingiva, 4 mm from the cementoenamel junction. The MSIs were immediately loaded, and PMICF was collected on days 0, 7, 14, 21, 28, and 42 and evaluated using a standard laboratory protocol. Surface morphology before placement and after retrieval of the MSI was observed using scanning electron microscopy (SEM) at a magnification of ×11, ×40, and ×1,000. Alkaline phosphatase (ALP) and aspartate aminotransferase (AST) levels observed were lower in the hybrid MSI in comparison to the cylindric MSI. For both MSIs, ALP and AST levels showed a trend of significant increase at days 0, 7, and 14 and then a significant decrease on days 21, 28, and 42. Observations from SEM showed an oxide layer over the entire surface of the bone-expanding hybrid MSI; this layer was observed only at the tip of the cylindric MSI. Levels of both the diagnostic tissue destruction biologic markers ALP and AST are significantly higher in cylindric MSIs compared with hybrid MSIs, indicating a correlation to the type and method of placement of the MSI. The inflammatory markers show a definitive trend, with an elevation until day 14 and a decline after that, indicating an active inflammatory process until day 14 that could be correlated to tissue trauma. Observations from the SEM show a greater oxide layer formation in the hybrid MSI, which could imply a better bone-MSI contact ratio.