M. W. Egan, D. A. Spratt, Y.-L. Ng, J. M. Lam, D. R. Moles & K. Gulabivala
Departments of Conservative Dentistry and Oral Pathology, Eastman Dental Institute for Oral Health Care Sciences, University College London, London, UK.

Aim.
To determine:

1. the relative prevalence and diversity of yeasts in salivary and root canal samples from the same patients; and
2. the clinical factors associated with their presence in saliva and root canals.

Conclusions.

1. The prevalence of yeasts in saliva was 32.7%.
2. The prevalence of yeasts in root canals associated with chronic periapical periodontitis was 10% (untreated root canals, 5.7%; previously treated canals, 16%).
3. There was a significant association between the presence of yeasts in saliva and root canal but the effect of previous root canal treatment and restoration leakage on the recovery of yeasts from root canal was equivocal.

E. V. Cruz, Y. Shigetani, K. Ishikawa, K. Kota, M. Iwaku & H. E. Goodis
Department of Operative Dentistry and Endodontics, Niigata University Faculty of Dentistry, Niigata City, Japan.
Manila Central University College of Dentistry, Manila, Philippines.
Division of Endodontics, University of California San Francisco School of Dentistry, California, USA.

Aim.
The aim of this study was to compare the sealing abilities of Fermin and Canseal with the more popular temporary coronal filling materials, Cavit and Caviton

Conclusion.
Amongst the four materials tested, Fermin was observed to provide a consistently tight seal even after being subjected to thermal and load cycling procedures. It was followed by Caviton and then Cavit. This study also showed that thermal cycling procedures seemed to affect the sealing ability of certain types of temporary endodontic filling materials whilst load cycling did not. These results further stress the importance of correctly placing a sufficient thickness of temporary filling material in endodontic access cavities to ensure a tight seal. Additional studies may be needed to verify the quality of seal provided by these materials for prolonged periods.

N. Özmeriç
Department of Periodontology, Faculty of Dentistry, Gazi University, Ankara, Turkey.

Aim.
To describe some toxic effects of arsenic trioxide in the mouth, to condemn its continued use, and present a case in which a tooth was preserved despite significant bony destruction.

Key learning points

• Arsenic and its compounds have no place in contemporary endodontics.
• Dentists should protect their patients by avoiding the use of arsenic-containing materials and refusing to use products whose constituents are not known.
• Localized bone necrosis may not require tooth extraction.

Depending on the severity of the case, the tooth may be preserved by a combination of endodontic, periodontal, prosthodontic and maintenance therapies.

M. L. Siers, W. L. Willemsen & K. Gulabivala
Department of Cariology and Endodontology, Faculty of Dental Science, University of Nijmegen, Nijmegen, the Netherlands.
Department of Conservative Dentistry, Eastman Dental Institute for Oral Health Care Sciences, University of London, London, UK.

Aim.
To initiate discussion on the value of routine root canal treatment for transplanted teeth.

Key learning points.

• Following transplantation original pulp tissue may survive the operation.
• Teeth with obliterated pulp space do not become necrotic more often than those without obliteration.
• Monitoring the tooth is an acceptable alternative to automatic root canal treatment for transplanted teeth.
• Root canal treatment should be undertaken only upon occurrence of pathological signs.

C. Dobo-Nagy, T. Serban, J. Szabo, G. Nagy  & M. Madlena
Department of Prosthetic Dentistry, Faculty of Dentistry, Semmelweis University, Budapest, Hungary.
Dental School, Medical University of Pecs, Pecs, Hungary.

Aim.
The purpose of this study was to compare the shaping characteristics of Ni–Ti K-files and Ni–Ti S-files manipulated by hand.

Conclusions.
Under the conditions of this study, preparation with Ni–Ti K-files produced more appropriate shapes in roots with apically curved canals than Ni–Ti S-files.