T. Kvist & C. Reit
Department of Endodontology and Oral Diagnosis, Faculty of Odontology, Göteborg University, Gothenburg, Sweden.

Aim.
There is substantial variation amongst dentists in the management of symptom-free periapical lesions in root-filled teeth. It has been suggested that this variation can be understood as clinicians’ choice of different cut-off points on a continuous periapical health scale (the ‘Praxis Concept (PC) theory’). Based on this suggestion, an individual’s inclination to propose retreatment can be expressed in the Retreatment Preference Score (RPS). In the present study it was hypothesized that:

1. the PC theory is valid amongst experienced endodontists; and that
2. interindividual variation in RPS can be explained by a corresponding variation in the perceived benefit of endodontic retreatment.

Conclusions.
Findings suggest that the PC theory is valid amongst endodontic experts. The study did not support the notion that the more potential utility that could be produced, the more the individual dentist should tend to perform retreatment. However, alternative consequentialist strategies focusing low risk taking may be involved.

A. Lussi, B. Suter, A. Fritzsche, M. Gygax & P. Portmann
Department of Operative, Preventive and Paediatric Dentistry, University of Bern, School of Dental Medicine, Bern, Switzerland.

Aim.
The aim of this in vivo study was to compare the radiographic quality of root fillings performed by the NIT-obturation method versus conventional mechanical obturation.

Conclusions.
The present investigation demonstrated the performance of the NIT-obturation method in vivo . Root canals filled by the reduced-pressure-method using sealer combined with gutta-percha cones exhibited equivalent radiographic quality compared to conventionally filled canals.

J. F. Siqueira Jr, I. N. Rocas, S. R. Moraes & K. R. N. Santos
Institute of Microbiology, Federal University of Rio de Janeiro, RJ, Brazil.
Department of Endodontics, Estacio de Sa University, RJ, Brazil.
Department of Microbiology, Immunology and Parasitology, School of Dentistry, Veiga de Almeida University, Rio de Janeiro, RJ, Brazil.

Aim.
The purpose of this study was to assess the prevalence of selected oral pathogens in root canal infections and their relationship with symptoms using a highly sensitive technique, the polymerase chain reaction.

Conclusions.
Direct molecular approaches appear to be a valuable tool for the rapid and reliable diagnosis of infectious diseases, as well as for research purposes. There was no correlation between target microbial species and symptoms.

1. Roots with thin dentine walls were more prone to root fracture during post removal.
2. The Eggler post remover can be used to remove cast posts/cores from teeth with minimal risk of root fracture when applied correctly.
3. Tooth damage may occur if the Eggler device is applied at an angle to the long axis of the tooth root. Care should be taken to ensure that the device is correctly aligned along the long axis of the tooth and the repeller arms contact the mesial and distal dentine surfaces uniformly and simultaneously. Point stresses or shear stresses in the dentine near the repeller arms may occasionally initiate root fracture due to incorrect positioning of the repeller arms.

E. V. Cruz, K. Kota, J. Huque, M. Iwaku & E. Hoshino
Departments of Operative Dentistry and Endodontics and Oral Microbiology, Cariology Research Unit, Niigata University School of Dentistry, Niigata, Japan.

Aim.
This study aimed to evaluate penetration of propylene glycol into root dentine.

Conclusion.
The results of this study indicate that propylene glycol could quickly and efficiently deliver dye through the root canal system. This suggests that propylene glycol may be useful in delivering intracanal medicaments into the root canal. The combination of propylene glycol and dye has the potential to allow for the visualization of tooth structures that could possibly be invaded and colonized by bacteria.