On the causes of persistent apical periodontitis: a review.

Apical periodontitis is a chronic inflammatory disorder of periradicular tissues caused by aetiological agents of endodontic origin. Persistent apical periodontitis occurs when root canal treatment of apical periodontitis has not adequately eliminated intraradicular infection. Problems that lead to persistent apical periodontitis include: inadequate aseptic control, poor access cavity design, missed canals, inadequate instrumentation, debridement and leaking temporary or permanent restorations. Even when the most stringent procedures are followed, apical periodontitis may still persist as asymptomatic radiolucencies, because of the complexity of the root canal system formed by the main and accessory canals, their ramifications and anastomoses where residual infection can persist. Further, there are extraradicular factors -- located within the inflamed periapical tissue -- that can interfere with post-treatment healing of apical periodontitis. The causes of apical periodontitis persisting after root canal treatment have not been well characterized. During the 1990s, a series of investigations have shown that there are six biological factors that lead to asymptomatic radiolucencies persisting after root canal treatment. These are: (i) intraradicular infection persisting in the complex apical root canal system; (ii) extraradicular infection, generally in the form of periapical actinomycosis; (iii) extruded root canal filling or other exogenous materials that cause a foreign body reaction; (iv) accumulation of endogenous cholesterol crystals that irritate periapical tissues; (v) true cystic lesions, and (vi) scar tissue healing of the lesion. This article provides a comprehensive overview of the causative factors of non-resolving periapical lesions that are seen as asymptomatic radiolucencies post-treatment

Stress, Personality, and Counterproductive Work Behavior

Counterproductive work behaviour (CWB) by employees is an all too common occurrence in organizations. Studies have shown that 95 per cent of employees have engaged in some form of CWB at least once (e.g. Penney, 2002). The costs to American businesses associated with just one type of CWB, employee theft, have been estimated to be more than $200 billion annually (Govoni, 1992). Given the prevalence and economic impact of CWB, the attention given to CWB by organizational researchers is not surprising. Two major threads in organizational research on CWB have developed over the years. One identifies environmental conditions that may serve as antecedents to CWB, such as the presence of job stressors, while the other focuses on the role that individual personality plays in the likelihood that an individual will engage in CWB. The purpose of this chapter is to discuss recent organizational research linking both of these streams, job stressors and personality, to CWB. First, the CWB construct and research is discussed briefly. Next, a conceptual model illustrating the relationships among job stress, personality, and CWB is presented as an organizing framework. Finally, specific job stressors and personality variables and their relationships with CWB are discussed