Receptor activator of nuclear factor kappa B ligand and osteoprotegerin expression in chronic apical periodontitis: possible association with inflammatory cells / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Receptor activator of nuclear factor kappa B (NF-κB) ligand (RANKL) and osteoprotegerin (OPG) have been recently shown to play important roles in bone resorption. The aim of this study was to investigate the possible association between the expression of bone resorption regulators (RANKL and OPG) and inflammatory cell infiltration in chronic apical periodontitis.</p><p><b>METHODS</b>The samples of chronic periapical lesions (n = 40) and healthy periapical tissues (n = 10) were examined for immunohistochemical analysis of RANKL and OPG. Lesion samples were further analyzed for the inflammatory infiltration condition. The inflammatory cell infiltration was scored in relation to immunohistochemical reactivity for CD3, CD20 and CD68.</p><p><b>RESULTS</b>The number of RANKL-positive cells and the ratio of RANKL/OPG in chronic apical periodontitis were significantly higher than those in healthy periapical tissues (P < 0.001). The number of RANKL-positive cells was higher in lesions with severe inflammatory infiltration than in those with light inflammatory infiltration (P < 0.05). Significantly increased RANKL expression was found with T lymphocytes (CD3(+)), macrophages (CD68(+)) and B lymphocytes (CD20(+)) infiltration (P < 0.05). No association was found between the ratio of RANKL/OPG and inflammatory cell infiltration.</p><p><b>CONCLUSIONS</b>RANKL expression was increased with T, B lymphocytes and macrophages infiltration, respectively in chronic periapical lesions. RANKL appears to be closely related to periapical inflammatory infiltrates. The relative ratio of RANKL/OPG may be a key determinant of RANKL-mediated bone resorption.</p>

Deformation evaluation of ProTaper nickel-titanium rotary instruments in curved canals instrumentation in vitro / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the deformation of ProTaper rotary instruments using in root canals of different curvature in vitro.</p><p><b>METHODS</b>Extracted first mandibular molars were divided into two experimental groups according to the curvature of mesial buccal canals: group A with moderate curvature and group B with severe curvature. Only the mesial buccal canals of all these teeth were prepared with 6 sets of new ProTaper rotary instruments individually. Additionally, the control group was established with a set of new ProTaper rotary instruments. After finishing each canal preparation, the instruments accompanied by control were examined under the stereomicroscope by an inspector without knowing the group. If distortion, unwinding, abrasion or fracture occurred within one set of instruments, then the whole set was disposed. The sets without problems were in use until 30 times. After 5, 10, 20 times canal preparation, S1, F1 files without deformation under stereomicroscope were examined under scanning electron microscope (SEM).</p><p><b>RESULTS</b>Deformation of ProTaper rotary instruments happened after 12 times in group A and after 7 times in group B. In these two experimental groups, microcracks were found increasing with the times of use under SEM in the instruments without deformation under stereomicroscope. The microcracks on tip of instruments were deep in the early use and became smoother after 10 times. Similar changes happened on knife-edge of instruments, and the microcracks extended over the edge after 20 times use.</p><p><b>CONCLUSION</b>Root canals with severe curvature tend to damage ProTaper rotary instruments more frequently than moderately curved canals. ProTaper rotary instruments are appropriate to treat less than 7 root canals with severe curvature or 12 root canals with moderate curvature. Stereomicroscope is recommended to detect early damages on Ni-Ti rotary instruments, for preventing instruments fracture in clinic.</p>

Comparative study of shaping efficiency in C-shaped canals of mandibular second molars / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the shaping efficiency of three instrumentation techniques in the C-shaped canals.</p><p><b>METHODS</b>Sixty extracted mandibular second molars with C-shaped canals were selected and cross-sectioned at 2, 5, 8 mm from the apex by using a muffle system as described by Bramante. The teeth containing C-shaped canals were randomly divided into three groups, respectively instrumented using stainless steel K-files in step-back and step-down techniques, and ProTaper series in crown-down technique. The digital images of canal cross-sections pre- and post-instrumentation were photographed to evaluate the proportion and position of uninstrumented area Working length loss and perforation were recorded. Data were analyzed using ANOVA.</p><p><b>RESULTS</b>Step-down technique gained smaller uninstrumented area in the coronal third of the canals, while step-beck technique gained the same results in the apical third (P < 0.05). Uninstrumented proportion in apical part was significantly higher than in the middle and the coronal (P < 0.05). Instrumenting type I canal as 2 or 3 separated canals was likely to reduce the miss. There were three perforations in manual stainless steel K-file groups.</p><p><b>CONCLUSIONS</b>Early opening the coronal part of C-shaped canal, shaping C-shaped canal as two or three separated canals and instrumenting the apical part with step-back technique, seemed to be the effective methods to avoid miss.</p>

Clinical evaluation of different angulation radiograph in diagnosing multiple canals of mandibular first premolars in vivo / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the efficiency of different angle projection radiograph in diagnosing multiple canals of mandibular first premolars.</p><p><b>METHODS</b>Eighty-eight mandibular first premolars that needed endodontic treatment in vivo were selected. The radiograph was taken at a horizontal angles of 0, 20-30 degrees from mesial or distal direction of the tooth preoperative. According to the different angle projection radiographic evaluation, radiographic diagnosis of multiple canals were suspected. After the root canal orifice were detected and located with K files, the root canals were prepared using crown-down technique and obturated using cold lateral condensation technique. The configurations and numbers of root canals were identified and recorded. The postoperative radiograph was taken. According to configurations and postoperative radiograph, the root canal configuration was classified into type I -V.</p><p><b>RESULTS</b>In eighty-eight mandibular first premolars, 31 multiple canals teeth were suspected in preoperative radiographic diagnosis, 30 multiple canal teeth were detected under clinical evaluation. In case of 31 multiple canal teeth suspected by preoperative radiographic diagnosis, 3 teeth were not found multiple canals under clinical evaluation. While in case of 2 teeth of one canal suspected by preoperative radiographic diagnosis, multiple canal was detected under clinical evaluation. In 31 multiple canal teeth suspected by preoperative radiographic diagnosis, 13 teeth were detected at a horizontal angles of 0 degree and 25 teeth were detected at a horizontal angles of 20-30 degree, 7 teeth were suspected at different angle projection. Clinical detected rate of multiple canal in mandibular first premolar were 34.09% (30/88), 70.00% of which were type IV and V.</p><p><b>CONCLUSION</b>Different angulation radiograph of preoperative will assist to increase clinical detection rate of multiple canals in mandibular first premolar.</p>

Clinical evaluation of the effect of angulation apical X-rays and the X-rays with file in diagnosing multiple canals in mandibular anterior teeth and premolars / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate different angle projection technique for the clinical detection and treatment of multiple canals in mandibular anterior teeth and premolars.</p><p><b>METHODS</b>Two hundred and forty-seven in vivo mandibular anterior teeth and premolars were selected from two hundred and fourteen patients. Four kinds of radiographs were taken for each tooth. The radiograph was taken at a horizontal angles of 0, 20 - 30 degrees from the mesial or distal of the tooth with and without files in canal. If a radiolucent line or files was present mesial or distal to the main canal, an additional canal was suspected. If the tooth appeared to have one large canal in the cervical or middle third of the root which disappeared or constricted as it traveled in an apical direction, an additional canal was suspected. The root canals were instrumented with ProTaper in crown-down mode and filled with laterally condensed gutta-percha and paste, the root canal configurations were classified into Types I - V.</p><p><b>RESULTS</b>60.92% multiple canals and 26.44% long oval canals were detected and treated from suspected multiple canals. The sensitivity of angle projection technique with file in X-ray diagnosing of multiple canals was 93.0%, and second canal was missed in four cases. The multiple canals in the 247 mandibular anterior teeth and premolars were present in central incisors: 9.43% (5 of 53); lateral incisors: 38.33% (23 of 60); canines: 15.90% (7 of 44), first premolar: 40.38% (21 of 52); second premolar: 2.63% (1 of 38).</p><p><b>CONCLUSIONS</b>The different angle projection technique will assist the clinician in the detection and treatment of multiple canals in mandibular anterior teeth and premolar, and angle projection technique with file detected more multiple canals.</p>

Location and negotiation of second mesiobuccal canals in maxillary molars / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate prevalence, location, negotiation and the effect of operating microscope (OM) in the treatment of the second mesiobuccal canal (MB2) in maxillary molars.</p><p><b>METHODS</b>113 maxillary molars were studied. The crowns of the teeth were removed 1 mm above the chamber bottom for searching MB2 canal. Initially location and negotiation of MB2 canal were attempted without OM. Teeth in which MB2 canal were not located or negotiated were further explored under OM. Canal orifices including MB orifice, MB2 orifice and palatal orifice were filled by red gutta-percha cones, then the teeth were scanned by scanner. The images were analyzed by Image-Proplus 4.0 software to measure the relationship between MB2 canal and other canals.</p><p><b>RESULTS</b>The MB-MB2 distance is (1.47 +/- 0.54) mm, MB-P distance is (5.77 +/- 0.66) mm, the vertical distance from MB2 to MB-P line is (0.53 +/- 0.28) mm, the angle between MB-P line and MB-MB2 line is 23.07 degrees +/- 13.08 degrees. MB2 orifices were located in 70 teeth (61.9%) and negotiated in 53 teeth (46.9%) without OM. With OM, additional MB2 orifices were located in other 6 teeth, 4 were negotiated; and 2 were negotiated in which MB2 canal were not negotiated without OM.</p><p><b>CONCLUSIONS</b>MB2 canal can be located in 67.3% and negotiated in 52.2% of maxillary molars. Ability to locate and negotiate MB2 canal is facilitated by OM. The MB2 canal was located less than 1 mm mesially to the MB-P line and 2 mm palatally from the MB orifice.</p>