The Operating Microscope In The Research Of Second Mesiobuccal Canals In The First Maxillary Molars

Root canal therapy is a method of treating pulp necrosis and periapical disease with the help of periapical tissues which are characterized by abundant blood flow and strong ability of repair and regeneration.Therefore.the ability to locate all the canals ih this system is an important factor in determining the eventual success of the case.If a canal is not detected.it cannot be cleaned and filled and is a potentiall cause of failure of endodontic therapy. So a dentist must know the shape of the canal system clearly before his treatment.It has been known that the first maxillary molars erupted early and supply the mainly function of chewing,it has hign incidence of dental caries.So the endodontic therapy is always essential.Due to its complicated canal system,especially the mesiobuccal canals,the treatment is often unsuccess.The morphologic feature of the root canal system of the first maxillary molars is always the hotspot which many scholars and clinicans researched for the past 75 years.Some researchs are focused on the incidence of the second mesiobuccal canal with different methods.But these studies have produced variable results in domestics and overseas.In recent years the operating microscope(OM)was introduced toendodontics.The fiber optic light of the OM provides x2.5 to x30.0 and has significantly improved magnifyication and illumination.beca-use the OM has become more widely used in endodontic treatment procedures,clinicians have indicated that it facilitates treatment of very fine canals,particularly the MB2 canal.The purpose of this study is to evaluate prevalence,location,negotia-tion and the effect of operating microscope in the treatment of the second mesiobuccal canal in the first maxillary molars.The experiment includes vitro study and clinical investigation.lt was divides into three parts:l.The prevalence and negotiation of MB2 in maxillary first molars with nake eyes and with OM.To investigate the frequency of the second mesiobuccal canal (MB2) in maxillary first molars and evaluate the effect of operating microscope (OM) in the location and negotiation of MB2.One hundred and ten maxillary first molars were used in this study. All the teeth were randomly divided into two groups. After removing the crowns 1 mm above the bottom of pulp chamber, the teeth were examined to detect MB2 by naked eyes and operating microscope respectively. The efficiency of locating MB2 using OM was evaluated by comparing with that by naked eyes. Results: MB2 orifices were located in 46 teeth (38.46%) with OM and negotiated in teeth. Conclusion: Ability to locate and negotiate MB2 canal is facilitated by OM.2.Location of second mesiobuccal canals in maxillary first molars.To investigate the relationship between the second mesiobuccal canal (MB2) and other canals (mesiobuccal canal, MB and palatal canal, P) in maxillary first molars and provide a morphological basis for locating canal orifice in endodontic therapy.Forty six maxillary first molars with MB2 were observed and measured under the XTL-2 photostereograph microscope. The MB2-MB, MB2-P and MB-Pdistances were measured. Results: The MB-MB2 distance is (1.800.24) mm. The vertical distance from MB2 to MB-P line is (0.71 0.19) mm. The palatal distance (PD) is 1.62 0.31mm. Conclusion: The MB2 canal was located less than 0.9 mm mesially to the MB-P line and 2 mm palatally from the MB orifice.3.Clinical evaluation of locating and identifying MB2 canal in maxillary first molar by operating microscope.To evaluate the efficiency of clinical application of operating microscope (OM) in locating the second mesiobuccal canal (MB2) in maxillary first molars.Forty one maxillary first molars, which were diagnosed as pulpitis or periapical periodontitis clinically, were selected and the MB2 canals were detected using naked eyes and OM respectively. The efficiency of locating MB2 using OM was evaluated by comparing with that using naked eyes.Results: The discovered incidence of MB2 is 15% (3/20) in naked eyes group and 47.61% (10/21) in OM...