Objective:To compare the efficacy of six different irrigation techniques on smear layer removal.Methods:60 single-rooted teeth were prepared.The root canals were irrigated with NaOCl at 20 ℃ or 60 ℃,and activated with side-vented needle,pas-sive ultrasonic irrigation (PUI)and EndoActivator (EA)irrigation techniques respectively.Then teeth were randomly divided into 6 groups(n =1 0):20 ℃-PUI group,20 ℃-EA group,20 ℃control group,60 ℃-PUI group,60 ℃-EA group and 60 ℃ control group.Smear layer was observed under thermal field emission scanning electron microscope(FE-SEM)and scored according to the cri-teria specified by Hulsmann M.Results:The smear layer removal effect in 60 ℃ groups was better than that in 20 ℃ groups (P <0.05),and better in 20 ℃-EA and 20 ℃-PUI groups than in 20 ℃ control group(P <0.05).Conclusion:The temperature of NaOCl is the main factor influencing the smear layer removal,NaOCl at 60 ℃ is more effective than that at 20 ℃.

Objective:To investigate the inhibition of Streptococcus oligofermentans(So)on Streptococcus mutans(Sm)and the hydro-gen peroxide(H2 O2 )producibility by So under different sucrose concentration environment.Methods:The inhibition of So on Sm was observed by plating method under different sucrose concentration environment.The initial synthesis rates and production of H2 O2 by So were determined by 4-aminoantipyine-horseradish peroxidase method.Results:Under 500 mmol/L of H2 O2 ,the inhibition of So on Sm was not observed.Under the other sucrose concentration environment,the inhibition of So on Sm was as following:50 mmol/L >0 mmol/L and 1 mmol/L(P <0.05);the initial synthesis rates of H2 O2 by So under different sucrose concentrations were as following:50 mmol/L >0 mmol/L and 1 mmol/L >500 mmol/L(P <0.05);the total production of H2 O2 by So:0 mmol/L and 1 mmol/L >50 mmol/L >500 mmol/L(P <0.05).When So was inoculated before Sm,the inhibition of So on Sm was stronger than that when the two species were inoculated at the same time.Conclusion:The capability of the inhibition of So on Sm and the production of H2 O2 by So are influenced by sucrose concentration.

BACKGROUND:In root canal preparation, the clearance effect of sodium hypochlorite for root canal irrigation on the smear layer is associated with the contact time and contact area of irrigation fluid, the amount of irrigation fluid, irrigation fluid temperature, irrigation fluid concentration, flushing methods and so on. OBJECTIVE:To investigate the clearance effect of 3% sodium hypochlorite on the smear layer of root canal under different flushing methods, flushing temperature and flushing time. METHODS:Totaly 180 isolated front teeth with single root were colected and root canal preparation was conducted using motorized ProTaper. The root canal was flushed with 3% sodium hypochlorite. According to different flushing methods, these root canals were randomly and evenly divided into root canal active flushing group, passive ultrasound swished group and side opening flushing needle group. According to the flushing temperature and the flushing time after replacing a file, each group was randomly divided into six subgroups: 20℃ 30 seconds group, 20℃ 60 seconds group, 37 ℃ 30 se group. The clearance effect on the smear layer of root canal was observed using scanning electron microscope. RESULTS AND CONCLUSION:The general clearance effect on the smear layer in the root canal active flushing group was better than that in the passive ultrasound swished group and side opening flush acupuncture group (P< 0.05). At the same time, the clearance effect on the smear layer in the 60℃ group was better that that in the 37 ℃ group and 20℃group (P < 0.05). At a certain temperature, the clearance effect on the smear layer in 60 seconds group was better than that in the 30 seconds group (P < 0.05). The clearance effect on the smear layer in the 1/3 root cap zone was better than that in the 1/3 root and 1/3 apical root zone (P < 0.05). These results show that the best clearance effect on the smear layer can be achieved as folows: 3% sodium hypochlorite irrigation at 60℃ for 60 seconds.

Objective:To evaluate the fracture resistance of roots instrumented with Reciproc,WaveOne,ProTaper and BLX respectively.Methods:50 extracted maxillary and 50 extracted mandibular anterior teeth were selected and randomly divided into 5 groups respectively(n =10).The teeth in the 4 experimental groups were instrumented by 4 the instruments respectively and the teeth in the control group were not treated.A vertical load was applied to the roots and the fracture load for each sample was recorded.The data were analyzed with SPSS 19.0 software.Results:After preparition the fracture load of the experimental groups was lower than that of the control (P ＜ 0.05),between the Reciproc and WaveOne groups (P ＞ 0.05),between ProTaper and BLX groups for maxi teeth (P ＞0.05),for mandibular teeth(P ＜ 0.05).The fracture load of Reciproc and WaveOne was higher than that of ProTaper and BLX(P ＜0.05).After making same taper shape using same root canal instrument,the mandibular anterior teeth had lower fracture resistances than the maxillary anterior teeth (P ＜ 0.05).Conclusion:Single-file reciprocating systems groups may decrease less fracture resistance than full-sequence rotary systems.with or without instrumentation,maxillary anterior teeth have higher fracture resistance than mandibular anterior teeth.

OBJECTIVETo investigate the linkage between dentinogenesis imperfecta type II and chromosome 4q21 in a Tianjin-Tanggu family of the Hui nationality.

METHODSBlood samples were collected from 13 family members. DNAs were analyzed with 8 STRP markers (D4S2915, D4S2932, GATA62A11, D4S2409, DSP STRP, SPP1 STRP, D4S1563, D4S1544) using fluorescence-based PCR. The linkage between eight markers on chromosome 4q21 and dentinogenesis imperfecta type II locus was tested respectively by lod score analysis.

RESULTSGenotype and haplotype were acquired. Genetic linkage analysis demonstrated the maximum lod score of eight STRPs were all larger than zero, in which five of them were larger than 1.

CONCLUSIONThe locus of dentinogenesis imperfecta type II in Chinese family is located on human chromosome 4q21, which indicated that the locus of Chinese Hui nationality should be the same as that of other reported European or American family.

Chromosome Mapping ; Chromosomes, Human, Pair 4 ; genetics ; DNA ; genetics ; Dentinogenesis Imperfecta ; genetics ; pathology ; Family Health ; Female ; Genetic Linkage ; Genetic Predisposition to Disease ; genetics ; Humans ; Male ; Microsatellite Repeats ; Pedigree ; Polymerase Chain Reaction

Objective: To study the influence of environmental factors on the two-species biofilm formed by the combinations of Streptococcus oligofermentans (So) with Streptococcus mutans (Sm) and Streptococcus sanguinis (Ss) with Sm so as to evaluate the role of So in maintaining the microecological balance of the oral cavity. Methods: Single-and two-species biofilms were grown on saliva-coated surfaces (glass tube and 96-well plate). Colony-counting method and safranin staining method were used to measure the biofilms formed under various oxygen conditions (aerobic and anaerobic), sucrose conditions (0%, 1% and 5% sucrose concentrations) and pH conditions (5.5, 6.0, 6.5, 7.0, 7.5 and 8.0). Results: Comparing the numbers of Sm in two co-cultures under various conditions, Sm counts in So+Sm group [(7.70±2.46)×10⁸ CFU/ml] were significantly lower than those in Ss+Sm group [(9.00±1.13)×10⁸ CFU/ml] in aerobic environment (P<0.05). Sm counts in So+Sm group [(2.80±0.52)×10⁸ CFU/ml] were also significantly lower than those in the Ss+Sm group [(4.00±1.25)×10⁸ CFU/ml] in anaerobic environment (P<0.05). The Sm counts in So+Sm group [(8.90±0.82)×10⁸ CFU/ml] were significantly higher than those in Ss+Sm group [(7.50±1.73)×10⁸ CFU/ml] in 0% sucrose environment (P<0.05). The Sm counts in So+Sm group [(5.70±2.94)×10⁸ CFU/ml] were significantly lower than those in Ss+Sm group [(10.30±3.21) ×10⁸ CFU/ml] in 1% sucrose environment (P<0.05). The Sm counts in So+Sm group [(6.10±1.71)×10⁸ CFU/ml] were also significantly lower than those in Ss+Sm group [(7.40±1.20)×10⁸ CFU/ml] in 5% sucrose environment (P<0.05). The Sm counts in So+Sm group [(3.50±1.50)×10⁸ CFU/ml] were significantly lower than those in Ss+Sm group [(10.70±2.80)×10⁸ CFU/ml] in pH7.0 environment (P<0.05). Comparing the formation of biofilm after 24 h cultivation, the Sm counts in So+Sm group were significantly lower than those in Ss+Sm group both in aerobic and anaerobic environments (P<0.05). The Sm counts in So+Sm group were significantly higher than those in Ss+Sm group in 0% sucrose environment (P<0.05). The Sm counts in So+Sm group were significantly lower than those in Ss+Sm group in 1% and 5% sucrose and pH 7.0 environments (P<0.05). Both So and Ss had no inhibitory effect on Sm in pH5.5 and pH8.0 environments. Conclusions In the in vitro two-species co-culture systems, So showed stronger inhibitory effects than Ss on Sm and its inhibitory ability might influenced by various environmental factors.

OBJECTIVES: This study aims to predict the risk of deep caries exposure in radiographic images based on the convolutional neural network model, compare the prediction results of the network model with those of senior dentists, evaluate the performance of the model for teaching and training stomatological students and young dentists, and assist dentists to clarify treatment plans and conduct good doctor-patient communication before surgery. METHODS: A total of 206 cases of pulpitis caused by deep caries were selected from the Department of Stomatological Hospital of Tianjin Medical University from 2019 to 2022. According to the inclusion and exclusion criteria, 104 cases of pulpitis were exposed during the decaying preparation period and 102 cases of pulpitis were not exposed. The 206 radiographic images collected were randomly divided into three groups according to the proportion: 126 radiographic images in the training set, 40 radiographic images in the validation set, and 40 radiographic images in the test set. Three convolutional neural networks, visual geometry group network (VGG), residual network (ResNet), and dense convolutional network (DenseNet) were selected to analyze the rules of the radiographic images in the training set. The radiographic images of the validation set were used to adjust the super parameters of the network. Finally, 40 radiographic images of the test set were used to evaluate the performance of the three network models. A senior dentist specializing in dental pulp was selected to predict whether the deep caries of 40 radiographic images in the test set were exposed. The gold standard is whether the pulp is exposed after decaying the prepared hole during the clinical operation. The prediction effect of the three network models (VGG, ResNet, and DenseNet) and the senior dentist on the pulp exposure of 40 radiographic images in the test set were compared using receiver operating characteristic (ROC) curve, area under the ROC curve (AUC), accuracy, sensitivity, specificity, positive predictive value, negative predictive value, and F1 score to select the best network model. RESULTS: The best network model was DenseNet model, with AUC of 0.97. The AUC values of the ResNet model, VGG model, and the senior dentist were 0.89, 0.78, and 0.87, respectively. Accuracy was not statistically different between the senior dentist (0.850) and the DenseNet model (0.850)(P>0.05). Kappa consistency test showed moderate reliability (Kappa=0.6>0.4, P<0.05). CONCLUSIONS Among the three convolutional neural network models, the DenseNet model has the best predictive effect on whether deep caries are exposed in imaging. The predictive effect of this model is equivalent to the level of senior dentists specializing in dental pulp.
Humans ; Deep Learning ; Neural Networks, Computer ; Pulpitis/diagnostic imaging* ; Reproducibility of Results ; ROC Curve ; Random Allocation