en ارتودنسی Orthodontics پژوهشي Research <strong>Introduction </strong><p> The purpose of this research was to evaluate microdamage accumulation after mini-implant placement by self-drilling (without a pilot hole) and self-tapping (screwed into a pilot hole) insertion techniques. The null hypothesis was that the mini-implant insertion technique would have no influence on microcrack accumulation and propagation in the cortical bones of the maxillae and mandibles of adult hounds.</p><strong>Methods</strong> <p> Mini-implants (n = 162 diameter, 1.6 mm length, 6 mm) were placed in the maxillae and mandibles of 9 hounds (12-14 months old) with self-drilling and self-tapping insertion techniques. The techniques were randomly assigned to the left or the right side of each jaw. Each hound received 18 mini-implants (10 in the mandible, 8 in the maxilla). Histomorphometric parameters including total crack length and crack surface density were measured. The null hypothesis was rejected in favor of an alternate hypothesis: that the self-drilling technique results in more microdamage (microcracks) accumulation in the adjacent cortical bone in both the maxilla and the mandible immediately after mini-implant placement. A cluster level analysis was used to analyze the data on the outcome measured. Since the measurements were clustered within dogs, a paired-samples <i>t</i> test was used to analyze the average differences between insertion methods at both jaw locations. A significance level of 0.05 was used for both analyses.</p><strong>Results</strong> <p> The self-drilling technique resulted in greater total crack lengths in both the maxilla and the mandible (maxilla: mean difference, 18.70 ± 7.04 μm/mm² CI, 13.29-24.11 mandible: mean difference, 22.98 ± 6.43 μm/mm² CI, 18.04-27.93 <i>P</i> <0.05), higher crack surface density in both the maxilla and the mandible (maxilla: mean difference, 10.39 ± 9.16 μm/mm² CI, 3.34-17.43 mandible: mean difference, 11.28 ± 3.41 μm/mm² CI, 8.65-13.90 <i>P</i> <0.05).</p><strong>Conclusions</strong> <p> This study demonstrated greater microdamage in the cortical bones of adult hounds in both the maxilla and the mandible by the self-drilling insertion technique compared with the self-tapping technique.</p><hr><p></p><p> <strong> Source: </strong>American<strong> </strong>Journal of Orthodontics and Dento facial Orthopedics </p><p><a href="http://www.ajodo.org/article/PIIS0889540612000613/abstract"><font color="#0000cc">  Full text</font></a> </p> 0 0 http://idai.ir/browse.php?a_code=A-10-32-482&slc_lang=en&sid=1 Surnit Yadav yadav_sumit17@yahoo.com 10031947532846001953 10031947532846001953 Yes Health Centre, University of Connecticut, Franington, Conn Madhur Upadhyay 10031947532846001954 10031947532846001954 No Health Centre, University of Connecticut, Franington, Conn Sean Liu 10031947532846001955 10031947532846001955 No Indiana University –Purdue University, Indianapolis Euqene Roberts 10031947532846001956 10031947532846001956 No Indiana University –Purdue University, Indianapolis William P. Neace 10031947532846001957 10031947532846001957 No University of Hatford, West Hatford, Conn Ravindra Nanda 10031947532846001958 10031947532846001958 No Health Centre, University of Connecticut, Franington, Conn