Stoll R, Urban-Klein B, Roggendorf MJ, JablonskiMomeni A, Strauch K, Frankenberger R. Effectiveness of four electronic apex locators to determine distance from the apical foramen. International Endodontic Journal, 43, 808-817, 2010.Aim To evaluate the accuracy of four electronic apex locators (EAL) in the apical region (0-3 mm short of the foramen) and to compare the precision of the readings on the display with the real position of the file in the root canal. Methodology Twenty single-rooted extracted teeth with round root canals were used. The canal orifices were preflared, and the length to the major foramen was determined visually under a microscope. Canals were enlarged, so that a size 15 file fitted well inside the canal. Teeth were mounted in acrylic test tubes filled with physiologic saline solution. Electronic length was determined in the region between the major foramen and 3 mm short of it in 0.5 mm steps with the Dentaport ZX, Root ZX mini, Elements Diagnostic Unit and Apex Locator and Raypex 5 using files of size 10 and size 15. The data were analysed using linear regression between true length and EAL reading, Bland-Altman plots and nonparametric tests at a significance level of alpha = 0.05. ResultsThe major foramen was detected by all EALs. With a measurement file positioned directly at the major foramen, meter readings were equivalent to a position 0.01-0.38 mm away. For the Dentaport ZX, a better accuracy using the size 15 file for the area 0-1.5 mm short of the apex was found. The differences in measurements between the two files were smaller for the other EALs. In linear regression, a good linearity for Dentaport ZX and Root ZX mini and moderate linearity for Elements Diagnostic Unit and Apex Locator and Raypex 5 were found. The slope of the measurement curve was too low (0.37-0.57) for the Raypex 5 and almost optimal for the Dentaport ZX (1.01-1.05). The Root ZX mini and the Elements Obturation Unit produced lower slope values and especially the Elements Obturation Unit revealed much higher SDs at the different measurement levels. Conclusion Amongst the four EALs, the Dentaport ZX and Root ZX mini had the best agreement between true lengths and meter readings. For the Raypex 5, an interpretation of the colour-coded zones as distance to the foramen cannot be recommended and might lead to erroneous interpretations.

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Sustainable Collection Services is a new venture for you. Tell us about it. Who are the partners? Is it a sole proprietorship, a sub-S, or another configuration? What is your remit? How many employees will you have initially? RL/RF: Sustainable Collection Services (SCS) grew directly out of R2's consulting work. In project after project, we saw libraries struggling to find space to accommodate users. Stacks are full, and yet print collection use is low and declining. Weeding and storage processes, especially for monographs, are incredibly labor-intensive. We realized that new thinking and new tools were needed to support efficient deselection, based on rules defined by the library. We decided it would be interesting to build one of those tools. We needed help, and called on our friends Andy Breeding and Eric Redman. In February 2010, we formed SCS as a partnership. We've known Eric for years in his role as Chief Architect and Director of Engineering at Blackwell's. He knows the MARC format inside out, and has long experience with large record sets. Andy and Rick met 20 years ago in the MLIS program at Simmons. Andy's skills in product design, user experience, and high-end SQL work were exactly what we needed, and he very much wanted to be part of a start-up. Ruth and Rick have previously built Web products and decision-support systems, and have spent years immersed in library workflows and strategies. The four of us make an excellent team. On our Website (http://sustainablecollections.com), we define our remit like this: Sustainable Collection Services (SCS) provides data-driven deselection services to academic libraries. SCS tools enable carefully managed drawdown of print monograph collections, while supporting shared print archiving efforts. ATG: Are you still running R2 Consulting? Can you tell us the difference/relation between the two companies/ventures? RL/RF: There is still strong demand for R2's services. For the past 18 months, we've been running both businesses. We've now decided to take our own advice and stop doing some tasks in order to focus on others. R2 will be on hiatus for 2012 so that we can work exclusively on SCS. We'll revisit that decision at the end of the year. ATG: As we understand it, you are focusing on deselection issues with Sustainable Collection Services. You have always focused on popular trends. Is deselection a trend driven by circumstances (need for space for example)? What is your definition of sustainable?