Accuracy comparison of implant impression techniques: A systematic review

Background Several studies link the seamless fit of implant-supported prosthesis with the accuracy of the dental impression technique obtained during acquisition. In addition, factors such as implant angulation and coping shape contribute to implant misfit. Purpose To identify the most accurate impression technique and factors affecting the impression accuracy. Material and Methods A systematic review of peer-reviewed literature was conducted analyzing articles published between 2009 and 2013. The following search terms were used: implant impression, impression accuracy, and implant misfit. A total of 417 articles was identified, 32 were selected for review. Results All 32 selected studies refer to in vitro studies. Fourteen articles compare open and closed impression technique, 8 advocate the open technique and 6 report similar results. Other 14 articles evaluate splinted and non-splinted techniques; all advocating the splinted technique. Polyether material usage was reported in 9; 6 studies tested vinyl polysiloane and 1 study used irreversible hydrocolloid. Eight studies evaluated different copings designs. Intra-oral optical devices were compared in 4 studies. Conclusions The most accurate results were achieved with two configurations: (1) the optical intra-oral system with powder; and (2) the open technique with splinted squared transfer copings, using polyether as impression material.

Listening to the public: enacting power : citizen access, Standing and influence in public participation discourses

Public participation in environmental governance is typically associated with citizen access to power despite many closures and limitations having been identified in participatory processes. This article proposes an analytical framework to analyse discursive practices involved in public consultation processes. Critical Discourse Analysis is used to examine and appraise citizens’ access, standing and influence. We apply that framework to a ‘notice and comment’ process on a hydroelectric power plan in Portugal and show that it was discursively managed to justify the decision of constructing 10 large dams and to reject critical or alternative views. Citizens’ access, standing and influence were constrained through diverse discursive practices which (re)produced very unequal power relationsbetween policy proponents and participating individuals. More generally, the article illustrates the potential of Critical Discourse Analysis to assess voice(s) in policy processes. Focusing on argumentative, interactional and rhetorical levels, and how they are interwoven in public consultation discourses, the proposed framework is conceivably applicable in other studies.