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Ya-qin Zhu

Publications and source records attributed to Ya-qin Zhu.

13 recordsLinked to original sources
PubMed2005

[Comparison of the effects of 5 irragant combinations on cleaning of anterior straight root canal walls].

PURPOSE: To evaluate the effect of 5 kinds of irrigant combinations on cleaning of anterior straight root canal walls. METHODS: 25 extracted human maxillary anterior teeth, with a single straight root were randomly divided into 5 groups. They were instrumented with K-files and conventional preparation technique. The irrigations were as follow: in group 1,the canals were irrigated with 1% NaOCl and 3% H2O2 in sequence during and after instrumentation.In group 2,the canals were irrigated with 1% NaOCl during instrumentation and after instrumentation being irrigated with 17% EDTA. In group 3,irrigation during and after instrumentation was accomplished using 17% EDTA and 1% NaOCl in sequence. In group 4,irrigation during instrumentation was accomplished using 17% EDTA and 1% NaOCl in sequence, and after instrumentation being irrigated with 17% EDTA.In group 5,the canals were irrigated with 17% EDTA, 1% Triton X-100 and 1% NaOCl in sequence during instrumentation and irrigated with 17% EDTA after instrumentation. The total amount of irrigant was 22ml and the irrigation time was 7 minutes in each root canal. The root was split longitudinally and 3 specimens in each group were evaluated regarding to the smear layer, debris and erosion of dentinal tubules with SEM at the coronal, middle and apical thirds. RESULTS: In group 1, typical amorphous smear layer and abundance of debris were seen on the wall of canals. In group 2, the smear layer was removed partly in coronal and middle thirds, but the apical surface of the canal walls were covered with a typical amorphous smear layer. Although irrigants of group 3 could remove smear layer effectively, it resulted in moderate erosion of dentinal tubules. In group 5, part of the smear layer was removed on the surface of coronal and middle thirds but abundance of debris were present on the surface at the apical levels. Severe erosion was noted on the root canal surfaces in this group. Irrigation of group 4 had the best result: it not only removed smear layer effectively ,but also had no erosion on dentinal tubules. CONCLUSION: Using the combination of 17% EDTA and 1% NaOCl can remove smear layer effectively and has no erosion on the dentinal tubules under the condition of strict time control and irrigation sequence. Supported by Phosphor Plan (No.01QB14025) of Science and Technology of Shanghai Municipality.

Dentin↗
PubMed2005

[Comparison on the shaping ability of three different instruments in preparing curved molar canals].

OBJECTIVE: To study the changes of root canal curvatures and apical transportation index when the curved root canals were prepared by hand-use ProTaper, stainless steel K-files or nickel-titanium K-files. METHODS: Forty-five extracted molars, with the degree of root canal curvature from twenty to forty, were divided into fifteen sections in curvature sequence. After that, three canals of each section were randomly distributed to three different instrumentation groups. One group of them was prepared by hand-use ProTaper with crown-down technique. The other two groups were instrumented by stainless steel or nickel titanium K-files with modified step-back technique to working length. The standard digital radiographs were taken to record the profiles of root canals and the positions of the tips of the instruments. The change of curvature degree between pre- and post-instrumentation and the apical transportation indexes (ATI) among three groups were analyzed respectively using SAS statistical software. RESULTS: The change of curvature degree between pre- and post-instumentation for stainless steel K-files group was largest, and the ATI of stainless steel K-files group was significantly greater than that for nickel titanium K-files group (P < 0.05). The canals prepared by hand-use ProTaper was smallest in the change of curvature and ATI among the three groups (P < 0.01). CONCLUSION: When preparing curved molar canals, hand-use ProTaper with crown down technique can obtain better shaping effect and higher efficiency.

Dental Instruments↗
PubMed2005

[In vitro evaluation of the sealing ability of an iodoform-calcium phosphorate cement root canal filler].

PURPOSE: To evaluate the sealing ability of an injectable iodoform-calcium phosphate cement(CPC) root canal filler in vitro. METHODS: Sixty-two single-rooted human extracted teeth were selected and root canals were instrumented to 40# with K file. Fifty-eight teeth were randomly divided into two experimental groups. The root canals were filled by lateral condensation of gutta-purcha with iodoform-CPC or zinc-oxide-eugenol-iodoform paste used as sealer respectively. Other four teeth were used as control. When the sealer was solidified, the apical portion of tooth was soaked into 2% methylene blue for 6 days. After the tooth was longitudinally sectioned, the dye length was measured for apical microleakage.The data obtained were analysed with group t test. RESULTS: The average microleakage in iodoform-CPC group(8.400mm) was significantly larger than that in the control group(5.300mm), P=0.021. CONCLUSIONS: We conclude that iodoform-CPC does not provide a sealing ability as good as zinc-oxide-eugenol-iodoform paste in vitro.

Calcium Phosphates↗
PubMed2005

[The influence of smear layer and different sealers on apical microleakage of root canals obturated with Ultrafil-3D system].

PURPOSE: To evaluate the sealing properties of Ultrafil-3D system with three different root canal sealers in absence or presence of smear layer. METHODS: 64 straight single-root anterior teeth were selected and root canals were instrumented. 60 teeth were divided into two groups with or without smear layer. Each group was then divided into three subgroups, three different sealers (AH-plus, Roekoseal, CRCS) were applied in each subgroup when the root canals were obturated with Ultrafil-3D system (using Firm set gutta-percha). Other 4 teeth were used as control. After dyed in 2% methyl blue for 5 days, all teeth were longitudinally split from mesiodistal surface into two parts. The linear length of dye was measured for apical microleakage. SAS6.04 software was used for statistical analysis. RESULTS: (1) The linear dye penetration was significantly higher in group A (CRCS) compared with that in group B (AH-plus) and in group C (Roekoseal) (P<0.05). (2) Whether the smear layer was absent or present, the apical microleakage had no significant difference when using gutta-percha of Ultrafil-3D system with the same sealer (P>0.05). CONCLUSION: Root-canal obturation with Ultrafil-3D gutta-percha can obtain better sealing ability when AH-plus or Roekoseal is applied as sealer. Removing the smear layer can not significantly reduce the apical microleakage.

Dental Leakage↗
PubMed2005

[Investigation of the current situation on clinical application of endodontic treatments in Shanghai municipality].

PURPOSE: To investigate the present state of endodontic treatments applied in Shanghai municipality. METHODS: A questionnaire survey about clinic application of three endodontic treatments including pulp mummification (PM), resinifying therapy(RT) and root canal therapy(RCT) was conducted by 136 dentists of 42 hospitals selected from three different types of hospitals in Shanghai. The questionnaire concerned the proportion and the scale of three treatments used clinically , the indications, the evaluation of the curative effect and the prospective application in future. SAS6.04 statistical software was used for Chi square test and Kruskal-Wallis test. RESULTS: (1) PM and RCT were applied widely, RT was seldom used. There was significant difference in the proportion using PM among three different types of hospitals (P<0.001). (2) PM was primarily applied to the teeth suffering from acute or chronic pulpitis, especially molars with vital pulp.(3)Good long-term curative effect was the primary factor affecting dentists to chose endodontic treatment.(4) Most dentists affirm that the best curative effect would be obtained for RCT, however, the effect was uncertain for PM to treat acute or chronic pulpitis. CONCLUSION: The current situation of clinical use of endodontic therapeutic methods in Shanghai falls some short of the concepts accepted internationally. But in general, RCT should be popularized while PM should be eliminated gradually.

China↗
PubMed2005

[Preliminary evaluation of the clinical results of calcium phosphorate cement root canal sealer].

PURPOSE: To investigate the clinic effect of calcium phosphorate cement as a root canal sealer-filler material. METHODS: 136 teeth with chronic periapical disease were instrumented and obturated with laterally condensed gutta-percha and either calcium phosphate cement(CPC) or iodoform paste. The patients were recalled and observed according to the clinic symptom and radiography after 1 week,3 months, 6 months and 1 year. The data was processed using SAS6.2 software package for Chi-square test and Wilcoxon rank test. RESULTS: The patients of CPC group had mild reaction after treatment and the successful rate of 3-month was higher compared with the control group(with iodoform paste), however there was no different clinical effects between the two groups after one year. CONCLUSION: Calcium phosphate cement root canal sealer can be acceptable for root canal filling , but the long term clinical results are needed be investigated.

Calcium Phosphates↗
PubMed2004

[Advances in investigation of calcified root canal therapy].

Calcified root canal occurs often during root canal therapy. It's important to understand various methods to deal with calcified root canal, which may increase the successful rate. From anatomy, radiography, chemical root canal preparation, ultrasonic root canal preparation and endodontic microscopic system etc., this paper reviews the present research about the treatment techniques for calcified root canal.

Dental Pulp Calcification↗
PubMed2004

[Effect of coronal preflaring on the instrumentation of curved premolar canals.].

PURPOSE: To study the effect of coronal preflaring on the instrumentation of curved premolar canals. METHODS: Sixty extracted premolars, with the degree of root canal curvature from fifteen to thirty-five, were divided into fifteen sections in curvature sequence. After that, four canals of each section were randomly distributed to four different instrumentational groups. Two groups were coronally preflared with Gates Glidden drills first. Then they were instrumented by stainless steel or nickel titanium K-files from 15# to 40# with sequential preparation to working length. The other two groups were prepared directly with the above-mentioned two instruments. The standard digital radiographs were taken to record the position of the tip of the different sizes of instruments. At last, the curvature degrees were measured and the apical transportation indexes (ATI) were determined under stereomicroscope. t test or rank test for paired data was used for statistical analysis. RESULTS: The curvature degree before and after instrumentation for each group was significantly different (P<0.01). The larger the files were, the greater the ATI became. The cases of root perforations in the stainless steel K-files group became fewer after coronal preflaring. The ATI of 30# for stainless steel K-files were much less after coronal preflaring, and were not significantly different with the ATI for nickel titanium instruments (P>0.05). CONCLUSION: The effect of nickel titanium instruments was superior to that of stainless steel instruments by comparing the change of curvature degree and the ATI of preparing curved premolars root canals. Coronal preflaring should be performed first when the root canals were instrumented by stainless steel K-files or nickel titanium instruments with sequential preparation technique.

Bicuspid↗
PubMed2003

[Using mineral trioxide aggregate as a direct pulp-capping material in dogs].

OBJECTIVE: The purpose of this study was to compare the dental pulp responses in dogs after MTA (Mineral Trioxide Aggregate) and a calcium hydroxide (Dycal) were applied as pulp-capping materials. METHODS: Twelve cuspids in three healthy adult beagle dogs were divided into two groups randomly. MTA or Dycal was used to repair the exposed site which was created with a fissure bur in a high-speed handpiece with copious water spray at the labial cervical access. Then the cavity was filled with glass ionomer cement (GIC). Four months later, the specimens were processed for histologic examination to observe the pulpal inflammation and dentin bridge formation. RESULTS: Five of six samples capped with MTA were free of pulpal inflammation, and all of samples in this group had dentin bridge formation. In contrast, all of samples capped with Dycal showed pulpal inflammation, and dentin bridge formation occurred in only 2 samples. CONCLUSION: MTA is a biocompatible material which can promote dentin bridge formation. It can be used as a direct pulp-capping material during vital pulp therapy.

Aluminum Compounds↗
PubMed2003

[Histological evaluation on repair of furcation perforation in dogs using mineral trioxide aggregate].

OBJECTIVE: To investigate histological response to immediate repair of different sizes of furcation perforation using MTA, Dycal and GIC. METHODS: Forty-two posterior teeth in three adult beagle dogs were randomly divided into two groups, small perforation group and large perforation group. Each group was then divided into three sub-groups which were repaired with MTA, Dycal and GIC respectively. The dogs were sacrificed 4 months later, and the specimens processed and examined under the light microscope. Inflammation, epithelial proliferation, and formation of hard tissue over the material were evaluated. RESULTS: In teeth repaired with MTA, five cases were free of inflammation, and the other nine cases were associated with slight or moderate inflammation. There was formation of cementum with cementoblast cells around it in four cases. In the group of Dycal, all specimens had moderate or severe inflammation. The deposition of irregular calcified tissues as well as a large quantity of inflamed cells were found in two cases of small perforation. Six cases presented epithelial proliferation. In the group of GIC, moderate or severe inflammation was seen in all cases except for one case of large perforation with fibrous tissues and sparse inflammatory cells around the material. Four cases presented epithelial proliferation. There was some relation between epithelial proliferation and size of perforation. CONCLUSION: MTA is superior to GIC and Dycal for immediate repairing furcation perforation in dogs owing to its less irritation to surrounding tissues and its ability to induce the formation of hard tissues.

Aluminum Compounds↗
PubMed2003

[Study on the reliability of two methods for measurement of root canal curvatures].

OBJECTIVE: To study the reliability of the degree of root canal curvatures with Schneider's and Weine's methods. METHODS: Fifty-one selected premolars were measured by three trained examiners with Schneider's and Weine's methods. RESULTS: Among the three examiners, the datas were not significantly different (P > 0.05) and linear correlation existed between the two methods (P = 0.0001). CONCLUSION: It was reliable to determine the degree of root canal curvatures using the two methods.

Dental Pulp Cavity↗
PubMed2002

[Analysis the stress variations of the root canal wall of pulpless tooth by different root canal preparation with finite-element method].

OBJECTIVE: To analyze the stress variations of the root canal wall of pulpless tooth by different root canal preparations. METHODS: On the basis of the set up model of the mandibular first molar, modified model was established by simulation of the routine or step-back root canal preparation and filling in. Then the maximum mises stress of each part of teeth and wall of root canal were calculated by special finite-element software. RESULTS: The stress-changing tendency is similar between two modified models but the maximum mises stress of the model by step-back technique is a little greater than one by routine. The stress of wall of mesial-buccal root canal was the greatest and one of mesial-lingual root canal was the least at three root canals. The stress-changing tendency of modified models was similar to original model. The maximum mises stress of modified models was near or less than one of original model except that of amalgam layer because of material property alteration. CONCLUSION: Not only routine but step-back technique is an effective and safe method. Dentist can choose them in practice.

English Abstract↗