Kenneth L. Zakariasen

Scanning electron microscopic analysis of canal wall dentin following neodymium-yttrium-aluminum-garnet laser irradiation

Five maxillary canines were split labiolingually and the canal concavities were debrided. At a series of evenly spaced locations along the canal wall, the concavity was flattened by an inverted cone bur to form small circular areas to be utilized as target locations. The specimens were stored in a thymolwater solution and subsequently rinsed in a 5.25% NaOCl solution for 1 min before lasing. The specimens were dried and lased from 10 to 90 W and 0.1 to 0.9 with a neodymium-yttrium-aluminum-garnet laser. Scanning electron microscopic analysis showed the effects of lasing to vary from no effects to disruption of the smeared layer to actual melting and recrystallization of the dentin, depending on such factors as power level, duration of exposure, and color of the dentin. The recrystallized canal wall dentin appeared to be nonporous and continuous in nature and could conceivably demonstrate reduced permeability to fluids.

Linear and volumetric analysis of apical leakage in teeth prepared for posts

The effect of post preparation on the apical seal of endodontically treated teeth was studied. The canals of extracted human teeth were instrumented and obturated with gutta-percha using the lateral condensation technique. Post spaces were prepared immediately or 48 h after obturation by removing the gutta-percha with either heated endodontic pluggers, chloroform and files, or Peeso reamers. Linear and volumetric measurements of resultant apical dye leakage revealed that no significant differences existed between the gutta-percha removal techniques at either of the two time intervals studied.

Endodontic recall radiographs: How reliable is our interpretation of endodontic success or failure and what factors affect our reliability?

Three hundred thirty cases were selected from an endodontic practice. Postoperative and recall radiographs of each case were examined by four endodontists for an interpretation of treatment success or failure. One hundred eighteen cases were examined a second time by each endodontist. Initial analysis showed substantial inconsistency in both inter- and intraobserver interpretation. The cases were then categorized by average radiographic density differences within radiograph sets, anatomic location of the treated tooth, technical compatibility within radiograph sets, and by length of time between postoperative and recall radiographs. It appears that these factors do not affect reliability of success/failure interpretation.

The effects of cyclical axial motion on rotary endodontic instrument fatigue

A potential problem with the use of rotary engine-driven files to flare canals is metal fatigue and subsequent breakage. This study analyzes the effects of cyclical axial motion on instrument failure by fatigue testing of endodontic files with and without cyclical axial motion. Eighteen new instruments, sizes 15 to 45, were mounted in a lathe and turned at 1650 rpm in the lubricated lumen of a curved Pyrex capillary tube until failure occurred. Nine instruments of each size were turned with cyclical axial motion and nine were turned without it. The results indicated that cyclical axial motion can significantly extend the life span of rotary engine files. Torsional forces were not considered in this study.

Corrosion and cytotoxicity evaluation of thermafil endodontic obturator carriers

The purpose of this study was to evaluate the in vitro cytotoxicity of two metallic and two plastic Thermafil carrier materials, and to separately evaluate the in vitro corrosion behavior of the two metallic carriers. Stainless-steel, Ti-6AI-4V, Polysulfone, and Vectra carriers were evaluated for cytotoxicity using the ISO-recommended agar overlay test. The two metallic carriers were additionally corrosion tested in 0.9% NaCl solution for 174 wk, at 37 degrees C. Elemental analyses of the corrosion solutions were periodically conducted using inductively coupled plasma-mass spectroscopy. Agar overlay results showed that the four carrier materials were not cytotoxic to L929 fibroblasts. Inductively coupled plasma-mass spectroscopy results showed that the metallic materials had small mass loss rates. Scanning electron microscopy showed no evidence of pitting or crevice corrosion.

Developing a public health leadership graduate program responsive to a global perspective

Purpose – The purpose of this paper is to describe a new public health leadership graduate program, and the incorporation of a practical global perspective to health leadership education using contemporary organization development inquiry methods to develop a case‐based learning strategy using graduate student‐authored cases.Design/methodology/approach – Case‐based curricula have been designed for the leadership and organizational change courses in the Public Health Leadership MPH Program that promote a global orientation and relevancy by having graduate students individually develop cases based on their experiences and observations in their own health care and social systems. They develop these cases using an extensive series of Appreciative Inquiry questions that focus on successful leadership practices, and the key stages involved in leading successful sustainable change. This method gives the students a framework to analyze leadership and leading change cases from the perspective of what the leaders t...

Rapid-cycle brainstorming: facilitating whole-systems change in time- and scheduling-challenged health care settings

Correspondence: Kenneth Zakariasen 3-50P University Terrace, 8303 – 112 St, edmonton, Alberta T6g 2T4, Canada Tel +1-780-492-1907 Fax +1-780-492-0364 email ken.zakariasen@ualberta.ca Abstract: Whole-systems approaches to organizational change dominate the contemporary change literature. They focus on widespread engagement of people within organizations, individual and collective ownership of both process and results, and encouragement of creativity and optimism regarding the future. One potential barrier to using whole-systems methods in health care is the frequent recommendation to bring many people together at the same time, sometimes for several days. In health care, it is very difficult to find blocks of time when a group can come together, even when the target unit is relatively small. Rapid-cycle brainstorming is an alternative process for using a whole-systems change method, in this case appreciative inquiry, in a time-efficient, effective manner for change planning in health care. It was used in this case to facilitate strategic planning for a hospital-based dental service for geriatric patients and persons with disabilities. The goals of this method for applying a whole-systems approach to change planning are (1) to minimize the time required to effectively work through the whole-systems process, while at the same time (2) to maximize the engagement of participants, (3) to develop creative synergism between small groups addressing specific planning topics, and when called for (4) to be able to facilitate the involvement of large numbers of individuals across an organization.