Study On Canal Isthmus In Maxillary Premolars

An isthmus is a narrow, ribbon-shaped, communication between two root canals that contains pulp or pupally derived tissue. It is also known as a corridor, a lateral interconnection, or a transverse anastamosis. Any root that contains two root canals has the potential to contain an isthmus . The isthmus may contain necrotic debris, tissue remnants or organic substrates that might support the growth of microorganisms. Failure to seal the isthmus will lead to eventual failure. The recognition and treatment of the canal isthmus may be one factor that will reduce the failure rate of surgical endodontics.There are many variations in the root and canal morphology of maxillary premolars. Regarding maxillary premolars, the configuration and the type of root canal were well studied, but there were few investigations for canal isthmus. The incidence of double root canal is high in the single-rooted maxillary premolars. So the incidence of canal isthmus is high. The purpose of this study is to investigate the incidence and location of the isthmus as well as the type of root canal configuration and the level of canal bifurcation or convergence in maxillary premolars.Objective: To investigate the incidence and location of the isthmus in extracted maxillary premolar with single root. The type of root canal configuration and the level of canal bifurcation or convergence were also examined.Methods: 50 maxillary first premolar and 60 maxillary second premolar were included in the study. Each tooth was embedded separately in clear resin. Starting at the root apex, the transverse section was stained with methylene blue dye after 1-mm root was resected, and viewed with a surgical operating microscope. The number of canals as well as the presence and type of canal isthmuses were recorded. Repeating the procedure at 1-mm increments to a level of 6mm from the apex.Results: In the maxillary first premolars with single root, 54.00% had two canals. Whereas 41.67% had two canals in the maxillary second premolars of single root. The incidence of an isthmus was highest in the apical 3-to 5-mm levels. Conclusions: Canal morphology in the apical 1-to6 -mm is complicated.The incidence of an isthmus in the maxillary first premolar was highest in the apical 4-6mm level. Whereas apical 3-5mm in the maxillary second premolars.