The aim of this study was to evaluate the microleakage of teeth according to root canal preparation with & without apical enlargement in various size of apical foramen. 60 extracted one canal roots were cross-cutted at 5 mm from root apex and divided into two groups according to their apical foramen size of large (L) and small (S). Each group was subdivided into two groups accordance with their cross-sectional configuration at 5 mm from apex, round (R) and ovoid (O); SR Group, SO Group, LR Group, LO Group. Each group was shaped in .02 taper by Quantec series Nickel-Titanium (NiTi) rotary file, obturated by lateral condensation method. Leakage was measured using a fluid transport model under 40 cmH2O pressure. After the leakage test, blocks which had showed the leakage retreated with .04 taper and .06 taper and evaluated the degree of fluid filtration in each group. The data was analysed statistically using chi-square test and fisher's exact test. The results obtained were as follows: 1. Significant difference in leakage was found in groups which had different apical foramen size in .02 taper instrumentation (p < 0.05), but not in .04 taper instrumentation (p > 0.05). 2. The difference in microleakage according to the shape of canal was not evident at 5 mm from apex (p > 0.05). 3. There was correlation between .02 taper instrumentation and .04 taper instrumentation in LR group , LO group (p < 0.05).
Filtration ; Root Canal Preparation ; Tooth Apex ; Tooth*

Humans ; Root Canal Therapy ; Tooth Apex ; Tooth Root ; injuries

OBJECTIVETo investigate the relationship between apical root resorption and orthodontic tooth movement in growing subjects.

METHODS58 growing subjects were collected randomly into the study sample and another 40 non-treated cases were used as control. The apical resoption of the upper central incisors was measured on periapical film and the incisor displacement was measured on lateral cephalogram. Using multiple linear regression analysis to examine the relationship between root resoption and the displacement of the upper incisor apex in each of four direction (retraction, advancement, intrusion and extrusion).

RESULTSThe statistically significant negative association were found between resorption and both intrusion (P < 0.001) and extrusion (P < 0.05), but no significant association was found between resorption and both retraction and advancement. The regression analysis implied an average of 2.29 mm resorption in the absence of apical displacement.

CONCLUSIONSThe likelihood that the magnitude of displacement of the incisor root is positively associated with root resoption in the population of treated growing subjects is very small.

OBJECTIVETo evaluate accuracy of Propex, Raypex 5, Root ZX electronic apex locator in positions of the perforation with different irrigations in the root canal.

METHODSPerforation lengths were measured with Propex, Raypex 5, Root ZX electronic apex locators in 19 extracted human teeth embedded in model after simulate perforation preparation by ultrasonic ET40 and compared with the actual canal length measurements taken before embedding the teeth in model. Measurements were taken with the different canal contents. RESULTS; Propex, Raypex 5, and Root ZX could locate the positions of the perforation with different irrigations in the root canal. The differences between actual root canal perforation length and measured root canal perforation length of same electronic apex locators in different irrigations were no statistically significant (P > 0.05). Meanwhile, the differences between actual root canal perforation length and measured root canal perforation length of three kinds of electronic apex locators in same irrigations were not statistically significant (P > 0.05).

CONCLUSIONPropex, Raypex 5, and Root ZX electronic apex locators can detect perforation accurately.

OBJECTIVETo compare the therapeutic efficacy both apexification and revascularization in the immature anterior teeth of animal model with apical periodontitis, and observe the histological situation of revascularization in the root canal.

METHODSSix immature anterior teeth of one animal model (dog) aged approximately 4.5 months was selected. Afterwards, periapical periodontitis pattern were established, the samples were randomly divided into the experimental group (revascularization, 3 teeth) and the control group (apexification, 3 teeth). To compare the development of root and the healing of periapical inflammation, the involved teeth were respectively radiographed 1, 4, 8 weeks after surgery. The animals were sacrificed after 8 weeks, and the closure of apical foramen and the content of root canal were observed by hematine-eosine (HE) staining.

RESULTSThe postoperative radiography after 1 week and 4 weeks, the apical foramen size and the periapical radiolucency of the samples was shown no perceptual change. After 8 weeks, the experimental group periapical radiolucency area was obviously more narrowing, and had a apical closure tendency whereas the thickness of the root canal walls had imperceptible changed. While the control group periapical radiolucency change varied. The granulation tissue could be seen within the lumen of the experimental group, which contained a large number of irregular calcification, the calcification was obvious in the apical and adjacent the root canal wall. A small quantity of hard tissue was deposited in the apical of the control group.

CONCLUSIONRevascularization may increase the recovery of immature anterior teeth with chronic periapical inflammation, the vital regenerative tissue within root canal is the granulation tissue contained calcification.

OBJECTIVEThe study was designed to investigate the relationship between the accuracy of Root ZX and the size of apical foramen, when the apical constrictions were intact or not. Methods Lengths were taken when the needle reached the '0.5' mark and 'APEX' mark on the Root ZX. The electronic apex locator (EAL)-measured canal working length (L2) and EAL-measured canal length (L1) were then compared with the actual canal working length (L') and actual canal length (L). Besides, the areas of apical foramens CS) were measured when the apical constriction were intact or not. Then the measurement deviations and the areas of apical foramens were analyzed by linear correlation and linear regression using the software SPSS 12.0. Statistical significance was considered at P < 0.05.

RESULTSThere were no significantly correlations between the area of apical foramen and the accuracy of Root ZX if the apical constriction was intact (P > 0.05). However, the accuracy of Root ZX and the size of apical foramen had significant negative correlation when the apical constriction was destroyed (P < 0.001). Then the linear regression was completed, and the linear regression equation was deltaL2 = -0.623 + 6.5965, so the critical area of the apical foramen was 0.135 mm2 if the tolerant error was set at 0.5 mm according to the statistic control.

CONCLUSIONThe size of apical foramen has little effect on the accuracy of Root ZX if the apical constriction is intact. However the measurements of Root ZX should be used carefully when the apical constriction was destroyed.

PURPOSE: The purpose of this study was to examine the patient- and treatment-related etiologic factors of external root resorption. MATERIALS AND METHODS: This study consisted of 163 patients who had completed orthodontic treatments and taken the pre- and post-treatment panoramic and lateral cephalometric radiographs. The length of tooth was measured from the tooth apex to the incisal edge or cusp tip on the panoramic radiograph. Overbite and overjet were measured from the pre- and post-treatment lateral cephalometric radiographs. The root resorption of each tooth and the factors of malocclusion were analyzed with an analysis of variance. A paired t test was performed to compare the mean amount of root resorption between male and female, between extraction and non-extraction cases, and between surgery and non-surgery groups. Correlation coefficients were measured to assess the relationship between the amount of root resorption and the age in which the orthodontic treatment started, the degree of changes in overbite and overjet, and the duration of treatment. RESULTS: Maxillary central incisor was the most resorbed tooth, followed by the maxillary lateral incisor, the mandibular central incisor, and the mandibular lateral incisor. The history of tooth extraction was significantly associated with the root resorption. The duration of orthodontic treatment was positively correlated with the amount of root resorption. CONCLUSION: These findings show that orthodontic treatment should be carefully performed in patients who need the treatment for a long period and with a pre-treatment extraction of teeth.
Female ; Humans ; Incisor ; Male ; Malocclusion ; Orthodontics ; Overbite ; Radiography, Panoramic ; Root Resorption ; Tooth ; Tooth Apex ; Tooth Extraction

OBJECTIVETo compare the shaping ability and the influence on apical foramen among hand ProTaper, stainless steel K-files and rotary ProTaper in preparing different curved root canal.

METHODSForty simulated resin root canal blocks were randomly divided into four groups and prepared by hand ProTaper, stainless steel K-file and rotary ProTaper, respectively. Of them, 12 blocks in group A, B, C consist of six 200 curved root canals and six 30 degrees curved root canals each group. The curvature of the other 4 blocks in group D was less than 5 degrees. Taking photos of the models to the root canal orthotopically and apical foramen using digital camera before and after instrumentation. Finally, the transportation of root canal and the size of apical foramen were analyzed using special image software Auto-CAD.

RESULTSThe transportation of center in group B was the highest than that in group A and group C (P<0.05). In some portions of root canal, the transportation of center in group C was higher than that in group A. The size of the apical foramen in group B was significantly bigger than the other groups and the size of the apical foramen in 30 degrees root canal was significantly bigger than that in 20 degrees root canal after instrumentation (P<0.05). There was no significantly different between group A and group C, though the size of apical foramen in group C was bigger than that in group A at the same curvature, and that in 30 degrees root canal was bigger than in 20 degrees root canal (P>0.05).

CONCLUSIONBoth of the two instruments engender root canal transportation, and curvature is the main reason of transportation. Comparing with stainless steel K-files, NiTi files can maintain the shape of the root canal and apical foramen well.

OBJECTIVETo evaluate the accuracy of Root ZX root apex locator in detecting stimulated horizontal root fractures.

METHODSA total of 20 single-canal maxillary anterior teeth were collected. All roots were simulated horizontal root fracture. Root ZX root apex locator measured the canal length in 3 stages: Broken ends of horizontal fractures without separation; broken ends of horizontal fractures with separation, but no impression material; broken ends of horizontal fractures with separation and impression material. The lengths measured by Root ZX root apex locator were compared with actual canal length.

RESULTSTo horizontal root fracture without separation or without impression material, Root ZX root apex locator couldn't detect the horizontal root fracture. To horizontal root fracture with separation and impression material, Root ZX root apex locator detected the horizontal root fracture within +/- 0.5 mm in 100%.

CONCLUSIONRoot ZX root apex locator lacks of diagnostic value for horizontal root fractures without soft tissue ingrowth, but provides with preferable veracity for horizontal root fractures with soft tissue ingrowth.

Constriction, Pathologic ; Humans ; Root Canal Obturation ; methods ; Root Canal Preparation ; methods ; Tooth Apex ; anatomy & histology ; pathology ; Tooth Diseases ; pathology ; therapy