Corticotomy-assisted and osteotomy-assisted tooth movement involves surgical incisions through the alveolar bone. To ascertain whether teeth move by distraction osteogenesis or by regional accelerated phenomenon (RAP), we randomly assigned 30 Sprague-Dawley rats to one of 5 experimental groups: corticotomy alone, corticotomy-assisted tooth movement, osteotomy alone, osteotomy-assisted tooth movement, or tooth movement alone. Each animal was imaged by microtomography immediately after surgery, after 21 days, and after 2 months. After 21 days, regional accelerated phenomenon was observed in the alveolar bone of the corticotomy-treated animals and distraction osteogenesis in the osteotomy-assisted tooth movement animals. Pixel count data were analyzed by nested ANOVA for 5 experimental groups, split-mouth controls, 3 levels along the root, and 5 sites per level. The most demineralized sites after 21 days differed for each of the experimental groups. Our study indicates that osteotomies and corticotomies induce different alveolar bone reactions, which can be exploited for tooth movement.

There is concern that widespread usage of ertapenem may promote cross-resistance to other carbapenems. To analyse the impact that adding ertapenem to our hospital formulary had on usage of other broad-spectrum agents and on susceptibilities of nosocomial Enterobacteriaceae and Pseudomonas isolates, we performed interrupted time-series analyses to determine the change in linear trend in antibiotic usage and change in mean proportion and linear trend of susceptibility pre- (March 2004-June 2005) and post- (July 2005-December 2008) ertapenem introduction. Usage of piperacillin-tazobactam (P=0·0013) and ampicillin-sulbactam (P=0·035) declined post-ertapenem introduction. For Enterobacteriaceae, the mean proportion susceptible to ciprofloxacin (P=0·016) and piperacillin-tazobactam (P=0·038) increased, while the linear trend in susceptibility significantly increased for cefepime (P=0·012) but declined for ceftriaxone (P=0·0032). For Pseudomonas, the mean proportion susceptible to cefepime (P=0·011) and piperacillin-tazobactam (P=0·028) increased, as did the linear trend in susceptibility to ciprofloxacin (P=0·028). Notably, no significant changes in carbapenem susceptibility were observed.

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