ABSTRACT
@#Root canal isthmus(RCI) is defined as a narrow, ribbon-shaped communication between two root canals that contains pulp or tissue derived from pulp. Any root that contains two or more root canals has the potential to contain an isthmus. The incidence of RCI from different tooth positions varies, with the highest RCI incidences usually found in the mesial root of the mandibular first molar and the mesiobuccal root of the maxillary first molar. The presence of RCI increases the difficulty of root canal therapy and introduces uncertainty regarding the prognosis for dental treatment. It is recommended to use CBCT and dental microscopy to identify teeth with suspected RCI in clinical practice. At the same time, for treatment of teeth with RCI, appropriate instruments should be selected, and enhanced root canal irrigation assisted by ultrasound should be considered to improve the success rate of root canal treatment and endodontic root-end surgery. The current technology still has some limitations regarding the cleaning and filling of RCI and additional research and development. Improvement of the corresponding technology and equipment is a current research hotspot and a future research direction.
ABSTRACT
Objective@#To investigate the differences in dentin structure, mineral content and microhardness of single premolar roots with or without an isthmus.@*Methods @#Thirty single-root premolars with a canal isthmus (experimental group) and thirty single-root premolars without a canal isthmus (control group) were collected and analyzed by scanning electron microscopy, X-ray energy spectrometry and a Vickers microhardness tester. Structure, mineral content and microhardness were compared. Results In the experimental group, the dentinal tubules were not obvious, and the structure was disordered. In the control group, the dentin tubules of the root canal wall were arranged regularly, and the lumen opening was clear. The Ca and P contents and Ca/P ratio of the experimental group were lower than those of the control group (P < 0.05). The microhardness of the experimental group was less than that of the control group (P < 0.05).@* Results@# In the experimental group, the dentinal tubules were not obvious, and the structure was disordered. In the control group, the dentin tubules of the root canal wall were arranged regularly, and the lumen opening was clear. The Ca and P contents and Ca/P ratio of the experimental group were lower than those of the control group (P < 0.05). The microhardness of the experimental group was less than that of the control group (P < 0.05).@*Conclusion@#The dentin structure of the root canal isthmus was changed, and the Ca, P contents and microhardness were low. The root canal isthmus was a weak link in the root, which could weaken the resistance of the hard tissue of the root tooth, which may be one of the important factors that could cause vertical root fracture.
ABSTRACT
Objective:To compare quantitatively the quality of the canal isthmus retropreparation among three kinds of ultrasonic ret-rotips.Methods:1 20 maxillary bicuspid teeth with two canals and an isthmus were randomly assigned to 3 groups(n=40).The canal isthmus retropreparation were made respectively using ultrasonic niti tip RE2,diamond tip Berutti and #25K file.Image processing and analysis system were used to measure the preoperative and postoperative parameters for further evaluation.Results:The cutting volume of ultrasonic niti tip RE2 group was significantly less than those of other two groups(P<0.05).Conclusion:Ultrasonic niti tip RE2 is feasible in the canal isthmus retropreparation.
ABSTRACT
Objective:To compare the quality of the canal isthmus retropreparation among three ultrasonic retrotips.Methods:120 maxillary bicuspid teeth with 2 canals and an isthmus were randomly assigned to 3 groups(n =40).The canal isthmus were retro-preparated by ultrasonic Ni-Ti tip RE2,diamond tip Berutti and #25K file respectively.The quality of cavity margin,the number and type of the micro-cracks were evaluated by SEM.Data were statistically analysed by Kruskal Wallis Test of SPSS 13.0.Results:The cavity margin quality of ultrasonic Ni-Ti tip RE2 group was superior to that of other 2 groups(P =0.003);The number of micro-crack in Ni-Ti tip RE2 group was less than that of other 2 groups(P =0.003).The type of micro-cracks has no significant difference among the 3 groups(P =0.830).Conclusion:Ultrasonic Ni-Ti tip RE2 is feasible in the canal isthmus retropreparation.
ABSTRACT
Objective: To investigate the root canal configuration and the incidence and location of the isthmus in extracted maxillary second premolar with single root. Methods: 60 maxillary second premolars were included in the study. 1 mm root was cut from the apical end of root. The transverse section was stained with methylene blue dye and viewed with a surgical operating microscope. 1 mm increment sections were made and stained and observed by the same way from apex to 6 mm. The number of canals as well as the type of canal isthmuses were recorded. Results: 41.67% maxillary second premolar with single root had two canals. Canal isthmus happened more frequently in the apical 4 mm levels. Conclusion: The incidence of isthmus in the maxillary second premolar was highest in the apical 3-to 5-mm level. Canal morphology in the apical 1-to 6-mm is complicated.