OBJECTIVETo investigate root canal curvatures of human maxillary first premolars in buccolingual directions.

METHODSOne hundred extracted permanent maxillary first premolars were used. After access preparation, a K-file was inserted into the canals and gently advanced until it reached the apical foramen. Then standardized periapical radiovisiography (RVG) images were taken from mesiodistal direction. The angle of curvature was determined according to the method described by Schneider. The radiu of curvature and length of the curved part of the root canal were calculated.

RESULTS1) The total 50.00% (88/176) of root canal curves were in buccolingual directions, and 53 curves were showed in apical 1/3 of root region. 11.93% (21/176) of S-shaped canals were detected, and the first curves were mostly showed in middle 1/3 of root region, the secondary curves were totally showed in apical 1/3 of root region. 2) There was no difference of curvatures between buccal and lingual root canals, but the secondary curves of S-shaped canals were more complicated than other root canals. 3) There was no correlation between the angle of curvature and the radius of curvature (r=0.002, P>0.05), but significantly correlation between the angle of curvature and length of the curved part of the root canal (r=0.489, P<0.01).

CONCLUSIONThe occurrence of curved root canals in buccolingual directions may be high in human maxillary first premolars, and the curvatures of S-shaped canals were more complicated than others.

Bicuspid ; Dental Pulp Cavity ; Humans ; Root Canal Therapy ; Tooth Root

OBJECTIVETo estimate the diagnostic potential of the dental operating microscope used for locating the second mesiobuccal canal (MB2) orifice in maxillary first molars.

METHODS120 extracted maxillary first molars were used, all the access cavities were prepared and fixed on the dental study model. MB2 orifices were examined with naked eye and under a dental operating microscope (DOM). The examination was repeated by another dentist with the same methods. Then Indian ink was injected into the pulp chamber and all the teeth were treated to be transparent to determine if it had a real MB2.

RESULTSThe sensitivity and accuracy of the DOM group were 0.78 and 0.76, higher than 0.61 and 0.65 of the naked eye group (P<0.05). The correspondency of Kappa index between observers by naked eye and DOM was 0.701 and 0.819, respectively.

CONCLUSIONThe use of DOM can increase the detection rate of MB2.

Dental Pulp Cavity ; Diagnostic Tests, Routine ; Humans ; Maxilla ; Microscopy ; Molar

OBJECTIVETo compare the shear bond strength of the fractured anterior teeth reattached by two different adhesive materials.

METHODSForty crown fractured anterior modes were divided into two groups randomly, with 20 in each group. Group A were reattached by Clearfil SE Bond and Clearfil AP-X, while group B were reattached by Clearfil S3 Bond and Clearfil AP-X. Then the specimens were submitted to an axial compression test in a universal testing machine until tooth fractured. The strength was recorded.

RESULTSThe mean shear bond strength of group A and group B was (324.32 +/- 65.91) N and (263.08 +/- 55.88) N, separately. The mean shear bond strength of group A was statistically higher than group B(t = 3.17, P = 0.000).

CONCLUSIONThe shear bond strength of two-step adhesive Clearfil SE Bond is higher than one-step adhesive Clearfil S3 Bond for the reattachment of fractured anterior teeth.

Adhesives ; Composite Resins ; Dental Bonding ; Dental Stress Analysis ; Dentin-Bonding Agents ; Humans ; Methacrylates ; Resin Cements ; Shear Strength ; Tooth Fractures

This case report describes the diagnosis and endodontic therapy of maxillary fused second and third molars, using cone-beam computed tomography (CBCT). A 31-year-old Chinese male, with no contributory medical or family/social history, presented with throbbing pain in the maxillary right molar area following an unsuccessful attempted tooth extraction. Clinical examination revealed what appeared initially to be a damaged large extra cusp on the buccal aspect of the distobuccal cusp of the second molar. However, CBCT revealed that a third molar was fused to the second molar. Unexpectedly, the maxillary left third molar also was fused to the second molar, and the crown of an unerupted supernumerary fourth molar was possibly also fused to the apical root region of the second molar. Operative procedures should not be attempted without adequate radiographic investigation. CBCT allowed the precise location of the root canals of the right maxillary fused molar teeth to permit successful endodontic therapy, confirmed after 6 months.
Adult ; Cone-Beam Computed Tomography ; methods ; Follow-Up Studies ; Fused Teeth ; diagnostic imaging ; Humans ; Image Processing, Computer-Assisted ; methods ; Imaging, Three-Dimensional ; methods ; Male ; Maxilla ; Molar ; abnormalities ; Molar, Third ; abnormalities ; Pulpitis ; diagnostic imaging ; Root Canal Therapy ; Tooth Root ; abnormalities ; Tooth, Supernumerary ; diagnostic imaging ; Tooth, Unerupted ; diagnostic imaging

OBJECTIVETo review and analyze the history and current situation of stomatological journals in China from 1949 to 2009.

METHODSThe data from journal database, web sites and yearbooks were collected, and the information on Chinese dental journals, national economic indicators and the development in dental disciplines from 1949 to 2009 were obtained.

RESULTSThe dental journals numbered one kind, four issues in 1949 and 32 kinds, 204 issues in 2009. China's gross domestic product (GDP) was from 67.9 billion Yuan in 1949 to 30.067 trillion Yuan in 2008.

CONCLUSIONSThe quantity of stomatological journals in China has increased remarkably over the past 60 years.

Bibliometrics ; China ; Economics ; History, 20th Century ; History, 21st Century ; Oral Health ; Oral Medicine ; Periodicals as Topic ; history ; Socioeconomic Factors

OBJECTIVETo draw a chorochromatic atlas of mortality on China Cancer Database in order to display the geographical distribution of selected diseases in China and to identify its demographic and disease-specific patterns in the 1990's.

METHODSThe source of data was from nationwide cause-of-death surveys conducted in the 1990's. Standardized rates were computed by direct method using the population age distribution in 1964 as the standard of weights. Inverse distance weight (IDW) was applied as the method of interpolation with the help of Arcview system to draw a choropleth map of cancer mortality.

RESULTSThe IDW maps of cancer mortality shows a continuous and smooth variation, especially compared with maps drawn by filling method.

CONCLUSIONWith the application of inverse distance weight interpolation, it seemed feasible to draw continuous map of cancer on sampling data.

Cause of Death ; China ; epidemiology ; Databases, Factual ; Geography ; Humans ; Neoplasms ; mortality

With the acceleration of the process of global integration, China’s international exchanges and cooperation with other countries have been further increased. The personnel exchange has led to the frequent occurrence of imported schistosomiasis from abroad, which seriously endangers people’s health. This paper reviews the prevalence and transmission risks of oversea imported schistosomiasis, providing the reference for the entry and exit health quarantine and prevention and control of schistosomiasis in China.