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BACKGROUND:Severely curved root canal preparation is the difficulty during clinical root canal preparation, and improper preparation may induce complications such as stage, root canal offset and apical open, which affect the quality of root canal preparation and apical closure. Therefore, it is important to choose a root canal preparation instrument which has the best cutting and forming ability. OBJECTIVE: To compare the shaping ability of Mtwo nickel-titanium rotary instruments, K3 nickel-titanium rotary instruments and stainless steel K-files for the preparation of curved root canals. METHODS:A total of 30 severely curved root canals of freshly extracted human maxilary molars were randomly divided into three groups, with 10 canals in each group. The canals were prepared by Mtwo instruments, K3 instruments and K-files, respectively. The instrument’s tip location in pre- and post-instrumentation radiographs of the three groups was recorded; the changes of root curvature, working length and working time in the three groups were measured and compared. RESULTS AND CONCLUSION:The root curvature showed no significant difference in the three groups before preparation (P> 0.05). The changes of root curvature after root preparation in Mtwo instrument and K3 instrument groups were significantly less than that in K-files group (P 0.05). The root canal preparation time in the three groups showed significant differences (P 0.05). Mtwo nickel-titanium rotary instruments and K3 nickel-titanium rotary instruments are have high efficacy and strong shaping ability in preparing curved root canals.
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Objective:To investigate the influence of 3 methods of fiber posts on fracture resistance of maxillary anterior teeth with flared root canals.Methods:32 human maxillary central incisors were assigned randomly to 4 groups(n =8).The crowns of the teeth were removed at a level 2 mm incisal to the cementoenamel junction(CEJ).After root canal therapy,flared canals were simula-ted in 3 groups.The flared canals were reinforced with resin cement(group A),resin composite(group B)and accessory posts (group C)respectively.In group D flared canals were not created.The same size fiber posts were cemented with resin cement in all groups.After posts cementation and composite resin core formation,all teeth were restored with metal crowns.Then the roots of the teeth were embedded in acrylic resin blocks up to 2 mm below the CEJ.The samples were loaded in a testing machine until failure occurred.Results:The maximum load value(N)for fracture of group A,B,C and D was 295.94 ±69.11,450.51 ±54.68, 479.37 ±77.81 and 618.51 ±87.42 respectively(F =118.127,P =0.000);group B vs C,P >0.05,between each 2 of the other groups,P 0.05). Conclusion:Reinforcement of flared canal with resin composite and accessory posts can increase the fracture restance of the tooth root and the most of fracture patterns are beneficial for the second repair.
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<p><b>OBJECTIVE</b>To detect the ability of Enterococcus faecalis (E. faecalis) biofilm formation and explore the relationship between E. faecalis biofilm formation ability and clinical manifestation.</p><p><b>METHODS</b>96 well plate with the establishment of 53 E. faecalis in vitro biofilm model, combined with crystal violet staining, was used to test the biofilm formation ability of the clinical isolates E. faecalis and analyze the relationship between biofilm formation capacity and clinical manifestation.</p><p><b>RESULTS</b>In total 53 E. faecalis strains, 40 strains(75.47%) had biofilm forming ability. Statistical analysis revealed that the capacities of biofilm formation between E. faecalis isolated from with fistula and without fistula was significantly different (P<0.05).</p><p><b>CONCLUSION</b>In the retreatment of root canal, the ability of biofilm formation of E. faecalis separated from the teeth without fistula is better than those separated from the teeth with fistula.</p>
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Humans , Biofilms , Dental Pulp Cavity , Enterococcus faecalis , Retreatment , Root Canal TherapyABSTRACT
Objective To assess the efficacy of NaClO irrigation of root canal at different temperatures.(Methods Thirty) human teeth with single root-canal mandible premolar were instrumented using standard technique,then were divided into 3 groups,carrying on root-canal irrigation.group A: 5.25% NaClO+System B,group B:5.25% NaClO+15% EDTA,group C:5.25% NaClO+System B+15% EDTA.After the teeth root were split,the scanning electron microscope was used to observe the coronal third,middle third and apical third parts.(Results The) amount of remaining debris on root canal wall in group C decreased significantly,compared with group A and B.The differences of coronal third and middle third between group A and B,group B and C,group A and C were significant(P0.05),but there were significant differences between group A,B and C(P
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In order to adapt to the development of society,an innovative talent cultivation system has been explored to train stomatological specialists with active innovation spirit and strong ability to practise.
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Objective:To evaluate the ability of calcium hydroxide removal using different irrigation methods and the effect on canal sealing.Methods:200 human single root canal premolar teeth were prepared.Divided the teeth randomly into 2 groups(each group 96 teeth,8 as control),one group filled with chemical calcium hydroxide and another filled with finished product calcium hydroxide.7 days after,divided each groups randomly into 6 subsets and remove the calcium hydroxide in the root canal(table1).Then each subset group choose 8 teeth randomly,observed by scanning electron microscope.Other specimens were obturated by lateral condensation of cold gutta-percha with a AH-Plus sealer,stained by Indian ink and then made into transparent teeth model.Results:At the same condition,there was no significant difference between group A and group B;the results of groups associated with ultrasonic were better than groups with injection syringe.The rinse solution EDTA was the best,distilled water was the worse.Dye penetration showed that the length of dye staining was no significant difference among all groups.Conclusion:Ultrasonic and sodium hypochlorite associate EDTA is the best method to remove the calcium hydroxide.But none of the methods and rinse solution used in this experiment can remove all of the calcium hydroxide.The calcium hydroxide remained influence on the root canal sealer is not predominance.