Z. Fuss, A.Mizrahi, S. Lin, O. Cherniak & E. I.Weiss
Department of Endodontology and Department of Restorative Dentistry, The Maurice and Gabriela Goldschleger School of Dental Medicine, Tel Aviv University, Tel Aviv, Israel.
Department of Prosthodontics, Faculty of Dental Medicine, Hebrew University, Jerusalem, Israel.

Aim.
The aim of this laboratory study was to evaluate the ability of calcium hydroxide (CH), CH/iodine-potassium iodide (IKI) and electrophoretically activated copper to kill bacteria in dentinal tubules.

Conclusions.
The present study demonstrated that the addition of IKI or electrically activated copper to CH significantly (P < 0.001) increased its antibacterial activity and their penetration into the dentinal tubules in vitro. Further studies are necessary to identify more effective nontoxic antibacterial agents and delivery systems that ensure direct contact of the medicament with bacteria in the dentinal tubules.

E. Schafer & D. Lohmann
Department of Operative Dentistry, University of Munster, Munster, Germany.

Aim.
To determine the cleaning effectiveness and the shaping ability of FlexMaster nickel-titanium rotary instruments and stainless steel hand K-Flexoашles during the preparation of curved root canals in extracted human teeth.

Conclusions.
With in the parameters of this study, manual instrumentation using K-Flexofiles resulted in better canal cleaning
than with rotary nickel-titanium FlexMaster instruments. FlexMaster instruments maintained the original curvature significantly better.

E. Schafer & D. Lohmann
Department of Operative Dentistry, University of Munster, Munster, Germany.

Aim.
The purpose of this study was to compare the shaping ability of FlexMaster rotary nickel-titanium instruments with stainless steel hand K-Flexoï¿ files. This part of the two-part report describes the efficiency of these two instruments in simulated curved root canals.

Conclusions.
Inconclusion, with in the limitations of the present study, the FlexMaster instruments prepared curved canals rapidly, without substantial change in working length, only with few canal aberrations and minimal transportation towards the outer aspect of the curve. Nevertheless, further studies will be needed to evaluate three-dimensional analysis of the prepared canal in order to assess smoothness, ï¿¡flow characteristics and taper of the enlarged canals.

K. S. Al-Fouzan
Dental Department, King Fahad National Guard Hospital, Riyadh, Kingdomof Saudi Arabia.

Aim.
The aim of this study was to determine the frequency of C-shaped canals in mandibular second molars in a population in Saudi Arabia and to establish a classiï¿ cation for the most common conï¿ gurations.

Conclusions.
Mandibular second molars with C-shaped canals vary in canal conï¿ guration. The early recognition of these conï¿ gurations facilitates cleaning, shaping, and obturation of the root-canal system. The possibility of CShaped canals has to be considered during the clinical and radiographic examination of the patient.

F. Maggiore,Y. T. Jou & S. Kim
Department of Endodontics, School of Dental Medicine, University of Pennsylvania, Philadelphia, USA.

Aim.
The aim of this case report is to describe an unusual six-canal maxillary first molar tooth.

Key learning points.

1. It should be assumed that all molar teeth have more than the traditionally expected three canals.
2. The location of root canals should be identified at high magnification under the microscope.
3. Careful radiographic re-examination of the fillings should be done in order to identify possibly missed canals.