S. M. Ardeshna, A. J. E. Qualtrough & H. V. Worthington
University of Manchester Dental Hospital, Higher Cambridge Street, Manchester, UK.

Aim.
This study aimed to measure and compare pH changes at apical and cervical sites on the external root surface of extracted teeth dressed with calcium hydroxide in two different formulations.

Conclusion.
The results of this study indicate that the rise in pH of root dentine at apical and cervical sites was significantly greater ( P < 0.001) in teeth dressed with a proprietary calcium hydroxide paste material compared with teeth dressed with calcium hydroxide points. For all groups, from 24 h, there was a significant difference in pH between apical and cervical sites with that at the apical being lower. Our findings confirm that placement of a calcium hydroxide material in either point or paste formulation as an interappointment dressing is effective at raising the pH at all external aspects of the root surface.

Y. Boucher, L. Matossian, F. Rilliard & P. Machtou
Unite de Formation et de Recherche (UFR) d’Odontologie de l’Université Paris 7, Service d’Odontologie de l’Hôtel Dieu, AP-HP, Paris, France.

Aim.
This study was undertaken to examine the prevalence and technical quality of root fillings and the periapical status of endodontically treated teeth in a French subpopulation.

Conclusion.
The results demonstrate a high prevalence of root-filled teeth and poor technical quality of treatment. Roots presenting with acceptable root fillings were associated with a lower prevalence of periapical pathology ( P < 0.001). Posts in roots were associated with periapical pathology significantly more than in roots without posts ( P < 0.001).

S. Aryanpour, P. Bercy & J.-P. Van Nieuwenhuysen
Department of Dental Medicine and Stomatology, Université Catholique de Louvain, Brussels, Belgium.

Summary.
The complex morphology of geminated teeth renders their endodontic and periodontal management difficult. Root canal and periodontal treatments were performed on a geminated mandibular first premolar with three canals. Clinical examination showed two separated crowns with united roots. Radiographically, two distinct pulp chambers with two joined and a third independent canal were seen. Conventional root canal treatment resulted in complete healing of the apical lesion. However, the occurrence of a vertical fracture led to the extraction of the mesial segment. At the follow-up visit, the distal segment was clinically healthy and continued to satisfy functional demands.

Key learning points.

• Failure to diagnose the initial crack along a gemination groove resulted in further propagation and finally complete vertical fracture.
  
• Owing to the abnormal morphology of the crown and the complexity of the root canal system in geminated teeth, treatment protocols require special attention.
  
• For asymptomatic cases without aesthetic or orthodontic problems and without associated pathosis, routine review and careful maintenance are required.

R. J. G. De Moor
Department of Operative Dentistry and Endodontology, Dental School, Ghent University Hospital, Ghent University, Gent, Belgium.

Aim.
This clinical report presents the endodontic treatment of two maxillary first molars and the anatomical study of two additional maxillary first molars with a C-shaped distally located root canal system. This configuration is not a common finding.

Summary.
According to the endodontic literature, the C-shaped root canal is most frequently seen in the mandibular second molar. The occurrence of C-shapes in maxillary first molars, however, has only been described in a limited number of case reports. We observed this configuration in two out of 2175 root-filled maxillary first molars treated at the Department of Endodontology, Ghent University Hospital, during the last 10 years. In order to study and visualize this particular aberration, cross-sections in two additional two-rooted maxillary first molars were made. From these cross sections it can be concluded that the C-shaped canal configuration is the result of a fusion of the distobuccal and the palatal roots.

Key learning points.

• C-shaped root canal morphotypes may occur in the distal portion of the pulp chamber in maxillary first molars.
  
• The C-shape results from a fusion of the distobuccal and palatal roots.
  
• The C-shape may extend to the apical third of the fused roots.

D. J. Caplan, J. Kolker, E. M. Rivera & R. E. Walton
Department of Dental Ecology, University of North Carolina, Chapel Hill, NC, USA.
Departments of Operative Dentistry and Endodontics, University of Iowa, Iowa City, IA, USA.

Aim.
The present study tested the hypothesis that having two proximal contacts (PCs) at access is associated with improved survival of root canal treated (RCT) teeth, controlling for important presenting conditions, endodontic variables and restorative factors

Conclusions.
In conclusion, if factors related to loss of RCT teeth are identified, their modification or elimination should lead to improved survival of RCT teeth. This study showed that RCT teeth with no or one PC at access were lost at more than three times the rate of RCT teeth with two PCs, controlling for crown status, tooth type, and presence of radiographic caries at access. Though recommendations for or against saving individual teeth should be made on a case-by-case basis, the influence of PCs on prognosis should be recognized during endodontic treatment planning if long-term retention of the tooth is a primary goal. Given the increasing emphasis on evidence-based decision-making in medical and dental care (Bray & Williams 1997, Dodson 1997), future research should provide data to support informed endodontic treatment decisions. Prospective designs that capture additional variables should be used, and outcomes related to costs of care also should be assessed (Klein et al. 1985, Maryniuk & Haywood 1990).