[The investigation on the situation of biting pencils among part pupils in Harbin, Guangzhou, and Beijing].

Objective: To investigate the prevalence of biting pencils among pupils living in Harbin, Guangzhou, and Beijing and to compare the differences among these cases. Methods: Stratified sampling method was used to select four elementary schools in Harbin and Guangzhou from April 2015 to April 2016. Firstly, Simple random sampling method was used in every grade (grade 1-grade 5) to select 3 or 4 classes (71 classes in total).After the sample selection, questionnaire surveys were conducted among pupils and their guardians (anyone of their guardians) who belonged to these classes. Secondly, the study extracted part of these pupils to conduct a field survey. Every school was classified by grade, and every grade adopted the method of random sampling to select one classes (20 classes in total). Meanwhile, the study randomly selected pupils from 10 classes in 2 elementary schools in Beijing. All together, 1 627 pupils participated in the field survey. The questionnaire included general information about the students and their guardians, the situation of biting pencils, the awareness of the harm of biting pencils, etc.; the field survey considered if participates' pencils have tooth marks and the severity of the marks, etc. χ(2) was applied to test and compare the differences among pupils of different genders and different cities. The comparison focused on the proportion of students who bited pencils, the proportion of pencils with tooth marks and the proportion of students and guardians already awared of the harm of biting pencils, etc. Results: The number of the valid questionnaires in Harbin and Guangzhou were 1 842, and 1 210, respectively. The occurrence rate of pupils biting pencils in Harbin (18.0% (333/1 842)) was higher than that in Guangzhou (11.3% (137/1 210)) (χ(2)=29.16, P=0.001). Specifically, in Harbin, the rate of boys biting pencils was 21.9% (212/965), which was higher than girls (13.8% (121/877)) (χ(2)=27.04, P=0.001). Similarly, in Guangzhou, the rate of boys biting pencils was 14.5% (92/632), which was also higher than girls (7.7% (45/578)) (χ(2)=15.34, P=0.001). The awareness rate of the harm of biting pencils among students from these two cities were 88.5% (1 611/1 819), and 90.8% (1 098/1 208), respectively, and the difference was statistically significant as well (χ(2)=4.39, P= 0.020). Compared with these data, the awareness rate of the harm of biting pencils among guardians from these two cities were 74.7% (1 339/1 791), and 79.4% (832/1 047), respectively as well as the statistically significant difference appeared (χ(2)=9.83, P=0.007). The result of field survey showed the rate of tooth-marked pencils in Harbin, Guangzhou and Beijing was 30.5% (187/613), 14.8% (79/534), and 28.3% (136/480), respectively. The difference was also statistically significant (χ(2)=42.68, P=0.001). The degree of tooth marks was mainly mild, while the percentage of mild degree in Guangzhou (54.4%(43/79)) and Beijing (41.2% (56/136)) was apparently higher than that of Harbin (39.0% (73/187)). The difference was not statistically significant (χ(2)=7.01, P=0.136). Conclusion: The behavior of biting pencils existed universally among pupils in Harbin, Guangzhou, and Beijing , which the situation of pupils biting pencils in Harbin and Beijing was more serious than that in Guangzhou. Pupils, parents and teachers should pay attention to such a behavior.

Cloning and characterization of peanut allene oxide cyclase gene involved in salt-stressed responses.

In this study, the full-length cDNA encoding allene oxide cyclase (AhAOC) was isolated from peanut (Arachis hypogaea L.). The deduced amino acid sequence of AhAOC showed high homology with other plant AOCs. The transcript of AhAOC was found to be abundantly expressed in roots. Expression analysis demonstrated that AhAOC was induced by abscisic acid, methyl-jasmonic acid, salicylic acid, salinity, polyethylene glycol, and cold stresses, particularly by high salinity. Overexpression of AhAOC in rice increased root elongation and plant height compared with expression in control plants and conferred tolerance against salinity. Thus, the AhAOC gene may play an important role in increasing the expression of transcription factors (MYB2 and OsONAC045) and functional genes (DREB1F and LEA3) in transgenic rice under salt stress as well as improve stress tolerance through the accumulation of compatible solutes (proline and soluble sugar). The AhAOC gene is a potential resource for enhancing salt tolerance in crop species.

A critical evaluation of physical and manufacturing properties of genuine and counterfeit rotary nickel-titanium endodontic instruments.

BACKGROUND: Rotary nickel-titanium (NiTi) instruments are made to exacting standards and are costly to manufacture, and quality control is paramount. Consequently, unauthorized factories make counterfeit instruments that are less expensive and may therefore be attractive to dentists. Little information exists about the metallurgy and manufacturing quality of such instruments. There is the potential for counterfeit instruments to be at higher risk of fracture during treatment, thereby compromising clinical outcomes. The aim of this study was to evaluate physical and manufacturing properties of genuine and counterfeit ProTaper Next™ and Mtwo® rotary NiTi instruments. METHODS: This study investigated the metallurgical properties, manufacturing quality, microhardness and number of cycles to failure of two commonly used rotary NiTi systems and compared them with counterfeit products purporting to be genuine articles. RESULTS: Counterfeit instruments were found to be inferior in manufacturing standards and were less resistant to cyclic fatigue when compared to genuine instruments. CONCLUSIONS: Counterfeit rotary NiTi instruments may be less efficient at preparing root canals and may be at higher risk of fracture during endodontic treatment. Dentists must be aware that, although less expensive, counterfeit instruments may be of dubious manufacturing quality and at higher risk of fracture if used in patients. © 2023 Australian Dental Association.

[Complications related to axial orientation of implants and their research progress].

The ideal axial orientation of implant is the key to the success of implant denture restoration. According to the restoration-oriented concept of implant, the implant axis direction should be consistent with the long axis direction of the suprastructure. In clinical practice, implant axial deviation leads to related complications, such as implant fracture, periimplant inflammation, and poor esthetic outcome of implant restoration, resulting in implant treatment failure. In this paper, complications related to improper implant axial orientation, their causes and treatment strategies are reviewed.

[Imaging observation and analysis of condylar osteosclerosis in temporomandibular joint osteoarthrosis].

Objective: To observe the different imaging manifestations of condylar sclerosis in temporomandibular joint osteoarthrosis and explore the imaging significance of condylar sclerosis. Methods: From January 2018 to December 2020, 50 patients with temporomandibular joint condylar sclerosis were examined by cone-beam CT (CBCT) and underwent spiral CT, MRI and radionuclide bone imaging at the Department of Oral and Maxillofacial Surgery in General Hospital of Chinese PLA. There were 15 males and 35 females aged from 16 to 65 years with age of (42.7±14.5) years. The imaging manifestations of CBCT, spiral CT, MRI and radionuclide bone imaging, joint disc displacement and abnormal bone metabolism of condylar sclerosis were analyzed. And the area of condylar sclerosis was graded according to the image of CBCT. Results: A total of 50 patients were included, including 38 unilateral condylar sclerosis, 12 patients with bilateral condylar sclerosis, the total condylar sclerosis were 66. There was no significant difference between the detection rate of further spiral CT (95.5%, 63/66) and CBCT (100.0%, 66/66) (corrected χ²=1.36,P=0.244). The area of condylar sclerosis was (35.5±4.5) mm2, ranged from 1 to 100 mm2. In addition, spiral CT showed more clearly condylar sclerosis than CBCT. Sclerosis can occur in all parts of condyle, mainly in the upper middle region (68.2%,45/66) in coronal position and in the upper front region (71.2%,47/66) in sagittal position. Fifty-seven condylar sclerosis were detected by MRI, including 4(4/19) condylar sclerosis less than 4 mm2. There was significant difference in the displacement of temporomandibular joint disc between the sclerotic side and the non sclerotic side (χ²=10.09, P=0.006). MRI display the condylar sclerosis showed low signal (56/62), followed by high signal (5/62) and medium signal (1/62). Radionuclide bone imaging showed that 4 of the 38 patients with unilateral condyle sclerosis had symmetrical bone metabolism, 34 had abnormal bone metabolism, and 21 patients had concentrated on the non-sclerotic side. Radionuclide bone imaging showed that 4 of the 38 patients with unilateral condyle sclerosis had symmetrical bone metabolism and 34 had abnormal bone metabolism. Conclusions: Spiral CT is more accurate than CBCT in terms of condyle sclerosis through different imaging analysis, and the detection rate of both is higher than MRI. Most of condylar sclerosis showed different degrees of low signal on MRI. The condylar sclerosis side is usually manifested by abnormal bone metabolism.

[Multimodal imaging analysis of the cyst like lesion of condyle in temporomandibular joint].

Objective: To investigate the imaging features of condylar cystic degeneration of temporomandibular joint (TMJ) by cone-beam CT (CBCT), spiral CT, MRI and radionuclide bone imaging. Methods: From January 2018 to December 2020, thirty-two patients with cyst-like lesions of condylein temporomandibular joint were examined by CBCT, spiral CT, MRI and radionuclide bone imaging at the Department of Oral and Maxillofacial Surgery in General Hospital of Chinese PLA. There were 12 males and 20 females involved, aged from 16 to 65 years with an average age of (33.9±12.5) years. The characteristics of CBCT, spiral CT, MRI and radionuclide bone imaging were analyzed. Condylar cyst like lesions were classified as type A and type B based on the presence or absence of surface bone defects. Condylar cyst like lesions were classified as type Ⅰ(yes) and type Ⅱ(no) according to the accompanying bone marrow edema-like lesions of the condyles. The incidence of condylar bone marrow edema, disc displacement and abnormal bone metabolism were analyzed. Results: A total of 64 joint images of 32 patients were included, including 34 sides with TMJ cyst-like lesion and 6 sides with multiple cyst-like lesions,the total cyst-like lesions were 42. The largest diameter of cyst-like lesion ranged from 1.0 to 12.4 mm, with an average length of (3.7± 1.8) mm. There were 24 cases of type A TMJ cyst like lesion and 10 cases of type B cyst-like lesion. The detection rate of CBCT was 95.2% (40/42) and that of spiral CT was 100% (42/42), there was no significant difference (Calibration Chi-square=0.51, P=0.474). The detection rate of nuclear magnetic resonance was 80.1% (34/42), and the detection rate of cyst-like lesions less than 2 mm was 3/11. In the cyst like lesion side, there were 9 sides with anterior disc displacement with reduction, 20 sides with anterior disc displacement without reduction. In the non-cyst like lesion side, 10 sides with anterior disc displacement with reduction and 6 sides with anterior disc displacement without reduction. There was a significant difference in the displacement of the disc between cyst-like and non-cystic lesion side (χ²=7.80, P=0.005). MRI showed that 6 cases of cystic side[17.6% (6/34)] had bone marrow edema-like lesions (all type A), 1 case of non-cyst like lesions side [3.3% (1/30)] had bone marrow edema-like lesion, there was no significant difference between cystic and non-cystic lesions (Calibration Chi-square=2.04, P=0.153). There was a significant difference between type A and B cystic lesions (Fisher exact probability method, P=0.024). Radionuclide bone imaging showed abnormal bone metabolism in 26 patients in the cyst-like lesion side and 5 patients in the non-cyst like lesion side (χ²=22.82, P<0.001). Conclusions Multi-slice Spiral CT could detect the cyst-like lesion of TMJ condyle in the early stage, which is different from the large joint. And the formation mechanism may vary from the different classifications.

[Research progress of dental pulp stem cells for peripheral nerve injury repair].

Peripheral nerve injuries are mainly related to severe trauma, fracture and tumor surgery, leading to reduced quality of life and impaired physical and mental health. The repair of peripheral nerve still faces great challenges in clinic, and the research on the regeneration and repair of peripheral nerve has become a hot issue in related disciplines. Cell therapy plays an irreplaceable role in tissue regeneration and repair. Schwann cells are ideal cells for peripheral nerve repair, but their limited sources inhibit the clinical application. Dental pulp stem cells are derived from neural crest, which provides a new cell source for nerve regeneration. The purpose of this article is to review the research progress of dental pulp stem cells for peripheral nerve repair.

[Reconstruction of zygomatico-orbtial and maxillary bone defects using three-dimensional printed customized prosthesis].

Objective: To reconstruct zygomatico-orbtial and maxillary bone defects using three-dimensional (3D) printing technology, so as to provide the basis for complicated maxillofacial bone defects. Methods: Five patients diagnosed with in zygomatico-orbtial and maxillary neoplasm in Department of Oral and Maxillofacial Surgery, General Hospital of Chinese PLA, who need bone defect reconstruction after surgery. Two different customized prosthesis were fabricated by computer aided design and 3D printing techonology, and the length of orbital floor extension in the customized prosthesis were different: Design 1, 9-10 mm orbital floor extension; Design 2, 10-15 mm orbital floor extension. The clinical outcome were evaluated during operation and matching condition of two different designed prosthesis were carried out after scanning for analysis. Results: The results indicated that the deviation value were 2-3 mm located at fixed structure during clinical evaluaton, and the deviation value were about 1 mm after prosthesis scanning. Finally, prothesis of Design 1 were applied for clinical use, and satisfactory reconstruction contour was achieved in all patients. Conclusions: The results suggest that zygomatico-orbtial and maxillary bone defects reconstruction can be conducted with satisfactory effect using 3D printing technology, and design and fabrication factors should be taken into consideration in complicated structure design with multi-protuberance.

[Design and application of three-dimensional printing guide plate for oral and maxillofacial surgery].

Objective: To explore the application of three-dimensional (3D) printing technology in oral and maxillofacial surgery, so as to optimize and standardize its design and application. Methods: From January 2010 to December 2020, 40 cases of mandibular tumor surgery (20 cases of conventional group and 20 cases of guide plate group), 20 cases of temporomandibular joint replacement surgery (10 cases of conventional group and 10 cases of guide plate group), 20 cases of malocclusion surgery (10 cases of conventional group and 10 cases of guide plate group), 20 cases of radioactive particle implantation surgery (10 cases of CT guided group and 10 cases of guide plate group) were analyzed. All patients in the guide plate group were scanned with spiral CT, and the 3D models of the jaw and the donor bone area were reconstruction. According to the purpose of surgical guide, the design and clinical application of osteotomy guide, in place forming guide and puncture positioning guide were analyzed respectively. The design time of guide plate, the performance and printing time of guide material, the sterilization method of guide and its influence on accuracy, and the influence of guide application on operation time and accuracy were analyzed. Results: The design time of orthognathic guide plate was (2.9±1.8) d, and the design time of mandibular transplantation guide plate was (2.8±1.8) d, that of the temporomandibular joint replacement guide plate and the puncture guide plate was (2.2±0.3) and (0.9±0.3) d. The average printing time of the 40 maxilla model was (11.1±1.6) h, and that of the 40 mandible models was (2.6±0.4) h. The average printing time of the 40 sets of osteotomy and positioning guide plate was (2.5±0.8) h, and that of the 10 puncture positioning guide plate (1.1±0.4) h. The operation time of the conventional group was (6.99±1.10) and (6.02±0.55) h. In the CT guided group, the operation time was (1.91±0.55) h and (0.89±0.15). The operation time of mandible tumor operation and radioactive particle implantation in the guide plate group was less than that in the control group (P<0.05), and there was no significant difference in the operation time of orthognathic surgery and joint replacement between the two groups (P>0.05). The displacement distance of the mark points in the TMJ replacement and mandibular tumor operation guide group was less than that in the control group (P<0.05), and the error of the guide plate in orthognathic operation and particle implantation operation was basically less than 1 mm. Conclusions: The application of the surgical guide plate made by 3D printing technology helps to complete the operation more safely, accurately and quickly, But its design, manufacture and disinfection still need to be further standardized and improved.

[Feasibility study of cone-beam CT for the analysis of cortical bone thickness in the posterior area of the jaw bone].

Objective: To investigate the feasibility of cone-beam CT (CBCT) in evaluating the thickness of cortical bone in jaw bone. Methods: Sixty patients [twenty-three for males and forty-seven for females, at an average age of (43.8±1.7) years] from Center of Stomatology, The First Affiliated Hospital of USTC & Anhui Provincial Hospital with 63 operational regions were included in the present study. Totally 63 bone sections from these areas were all selected at last. Case Viewer and oral dynamic system were used for the measurements in sections and CBCT graphs of the cortical bone thicknesses at alveolar ridges. Paired samples t test was performed to compare the difference between CBCT measurement and Case Viewer measurement. Results: The cortical bone thicknesses measured by Case Viewer were (1.20±0.75), (0.68±0.46) and (1.48±0.77) mm in the posterior, maxillary posterior and mandibular posterior areas, respectively. The cortical bone thicknesses measured by dynamic navigation software were (1.14±0.77), (0.64±0.24) and (1.41±0.83) mm in the posterior, maxillary posterior and mandibular posterior areas, respectively. There were no significant differences between either the two methods or the different areas (P>0.05). Conclusions: CBCT would be a useful equipment for the analysis of cortical bone thickness with a reliable and convincible accuracy.

Simulation of postoperative occlusion and direction in autotransplantation of teeth: application of computer-aided design and digital surgical templates.

Autotransplantation of teeth requires optimisation of both occlusion and direction to ensure minimal injury to the dental crown and the alveolar bone. We describe a method that could simulate postoperative occlusion and direction of the donor tooth by using CAD and digital surgical templates, and evaluate the postoperative effect in five patients who had teeth autotransplanted. Computed tomographic data were imported into ProPlan CMF 3.0 software, the donor tooth was simulated to replace the recipient site according to the position of the occlusion and alveolar bone, and a digital template was designed to guide preparation of the socket. A computer-aided, rapid prototyped, tooth was used to match the socket and, finally, an occlusal template was designed to ensure that the donor tooth was in the simulated position. We compared the position of the tooth in the simulation with its postoperative position using ProPlan CMF 3.0 software. In this way it was possible to simulate and guide the donor tooth accurately to the recipient site. At six-month follow up all teeth had survived successfully. Given the efficiency and precision of placement and the success, we conclude that CAD can successfully help to simulate occlusion and direction in autotransplantation of teeth while simplifying the procedure.

[Epidemiological characteristics of imported acute infectious diseases in the border areas of Yunnan province, 2008-2017].

Objective: To understand the epidemiological characteristics of imported acute infectious diseases between 2008 and 2017 in the border areas of Yunnan province. Methods: All the cases occurred between January 2008 and December 2017 and related information was from the Chinese CDC infectious disease report information management system, according to definition of imported cases diagnosed by clinicians. Epidemiological characteristics of the imported cases of related information were gathered. Results: A total of 13 157 imported acute infectious diseases were reported from the border areas of Yunnan province, which accounted for 6.03% (13 157/218 284) of the total number of acute infectious diseases in the same areas from 2008 to 2017. Malaria, dengue fever and hand-foot-mouth disease were accounted for 56.05% (7 374/13 157), 21.82% (2 871/13 157) and 4.62% (608/13 157), of all the case, respectively. The number of imported malaria cases decreased annually. However, dengue fever showed a sharp increase. Peaks of the epidemics appeared as: May for malaria and October for dengue fever. Male patients were accounting for the majority (73.22%, 9 634/13 157), so as the patients with Chinese nationality (54.91%, 7 225/13 157). The age distribution appeared as: 67.12% (8 829/13 157) for the 15-44 year olds and 19.26% (2 535/13 157) were children below 14 years of age. Proportions of occupation appeared as: farmers (45.23%, 5 596/13 157), migrant workers (21.30%, 2 802/13 157) and children living at home (11.12%, 1 463/13 157). Most of the imported cases were coming from Myanmar and appearing in the following three counties: Ruili city, Tengchong city, and Yingjiang of Yunnan province. Cities/counties that with number of imported cases more than 10% of the local reported cases, would include Ruili city, Tengchong city, Zhenkang county and Mangshi of Yunnan province. Conclusions: Imported acute infectious disease was a serious public health problem in Yunnan province, 2008-2017. The main imported acute infectious diseases were malaria, dengue fever and hand-foot-mouth disease. The majority imported cases were accounting for Chinese, male, young adults and farmers. It is also important for immigration workers to carry out surveillance, prevention and control programs on infectious diseases when working in neighboring countries.

Effect of a beta-adrenergic blocking agent on dental anxiety.

The effect of propranolol was studied on 23 dental phobics in a double-blind, placebo-controlled clinical trial involving actual dental treatment. The subjects were selected because they showed high physiological reactivity in the dental situation. Twelve subjects received the test drug and 11 subjects received the placebo at individualized doses of either 80 or 120 mg. A significant difference in self-reported anxiety at the injection phase of treatment and less overall pain intensity and aversiveness were observed for the propranolol as compared with the placebo group. No differences were detected for behavior ratings. Beta-adrenergic blocking agents may have utility for reducing anxiety in individuals fearful of dental treatment.

Calculating dose distributions and wedge factors for photon treatment fields with dynamic wedges based on a convolution/superposition method.

A convolution/superposition based method was developed to calculate dose distributions and wedge factors in photon treatment fields generated by dynamic wedges. This algorithm used a dual source photon beam model that accounted for both primary photons from the target and secondary photons scattered from the machine head. The segmented treatment tables (STT) were used to calculate realistic photon fluence distributions in the wedged fields. The inclusion of the extra-focal photons resulted in more accurate dose calculation in high dose gradient regions, particularly in the beam penumbra. The wedge factors calculated using the convolution method were also compared to the measured data and showed good agreement within 0.5%. The wedge factor varied significantly with the field width along the moving jaw direction, but not along the static jaw or the depth direction. This variation was found to be determined by the ending position of the moving jaw, or the STT of the dynamic wedge. In conclusion, the convolution method proposed in this work can be used to accurately compute dose for a dynamic or an intensity modulated treatment based on the fluence modulation in the treatment field.

A dual source photon beam model used in convolution/superposition dose calculations for clinical megavoltage x-ray beams.

A realistic model of photon beams generated by clinical linear accelerators has been incorporated in a convolution/superposition method to compute dose distributions in photon treatment fields. In this beam model, a primary photon source represents photons directly from the target, and an extra-focal photon source represents scattered photons from the primary collimator and the flattening filter. Monte Carlo simulation was used to study clinical linear accelerators producing photon beams. From the output of the Monte Carlo simulation, the fluence and spectral distributions of each photon component, as well as the geometrical characteristics of each photon source with respect to its distance to the isocenter and its source distribution, were analyzed. These quantities were used to reproduce realistic photon distributions in treatment fields, and thus to compute dose distributions using the convolution method. Our results showed that compared to the primary photon fluence, the extra-focal photon fluence from the primary collimator and the flattening filter was 11%-16% at the isocenter, among which 70% was contributed by the flattening filter. The variation of extra-focal photons in different treatment fields was predicted accurately by accounting for the finite size of the extra-focal source. Compared to measurements, dose distributions in photon treatment fields, including those of asymmetric jaw settings and at different SSDs were calculated accurately, particularly in the penumbral region, by using the convolution method with the new dual source photon beam model.

Modeling photon output caused by backscattered radiation into the monitor chamber from collimator jaws using a Monte Carlo technique.

Dose per monitor unit in photon fields generated by clinical linear accelerators can be affected by the backscattered radiation into the monitor chamber from collimator jaws. Thus, it is necessary to account for the backscattered radiation in computing monitor unit setting for a treatment field. In this work, we investigated effects of the backscatter from collimator jaws based on Monte Carlo simulations of a clinical linear accelerator. The backscattered radiation scored within the monitor chamber was identified as originating either from the upper jaws (Y jaws), or from the lower jaws (X jaws). From the results of Monte Carlo simulations, ratios of the monitor-chamber-scored dose caused by the backscatter to the dose caused by the forward radiation, R(x,y), were modeled as functions of the individual X and Y jaw positions. The amount of the backscattered radiation for any field setting was then computed as a compound contribution from both the X and Y jaws. The dose ratios of R(x,y) were then used to calculate the change in photon output caused by the backscatter, Scb(x,y). Results of these calculations were compared with available measured data based on counting the electron pulses or charge from the electron target of an accelerator. Data from this study showed that the backscattered radiation contributes approximately 3% to the monitor-chamber-scored dose. A majority of the backscattered radiation comes from the upper jaws, which are located closer to the monitor chamber. The amount of the backscatter decreases approximately in a linear fashion with the jaw opening. This results in about a 2% increase of photon output from a 10 cm x 10 cm field to a 40 cm x 40 cm field. The off-axis location of the jaw opening does not have a significant effect on the magnitude of the backscatter. The backscatter effect is significant for monitor chambers using kapton windows, particularly for treatment fields using moving jaws. Applying the backscatter correction improves the accuracy of monitor-unit calculation using a model-based dose calculation algorithm such as the convolution method.

A cross-cultural cross validation of the Dental Fear Survey in South East Asia.

This study was designed as a cross-cultural replication and cross validation of the Dental Fear Survey (DFS) in two groups of Singapore adults: university students and military conscripts. Factor analysis of the DFS in each of these dissimilar samples revealed factor structures that were highly comparable to one another as well as to those obtained in the U.S.A. Behavioral and physiological fear assessment during exposure to simulated dental treatment also showed results comparable to those found in Western cultures. Self report measures were more likely to correlate with other self reports than with physiologic or behavioral measures. Among university students, those who had visited a dentist within the past year had significantly lower DFS scores than those who had avoided dentistry. The fear-avoidance relationship did not hold for military subjects who reported less dental fear overall. It was concluded that the DFS was factorially stable; and therefore, generalizable to this South East Asia culture.

Cracked teeth--treatment rationale and case management: case reports.

The treatment rationale for, and successful management of, six teeth with cracks in the form of incomplete vertical fractures are reported. Further crack propagation was prevented by placement of either stainless steel orthodontic bands or aluminum or acrylic resin provisional crowns, and endodontic treatment was subsequently carried out. The teeth were restored with intraradicular amalgam cores and complete veneer crowns. The teeth were reexamined periodically for up to 3.5 years after treatment. During the period of review, all teeth remained asymptomatic.

Crown diameters of the deciduous teeth of Taiwanese.

The purposes of this study were (1) to characterize the crown diameters of the deciduous teeth of Taiwanese; (2) to compare the differences in the deciduous crown diameters between different populations. The results might provide odontometric information in making preformed stainless steel crowns of the Chinese population. Study casts of 90 children (51 boys and 39 girls) of aged 3 to 6 years were used in this study. The maximum mesiodistal crown diameter (the greatest distance between the contact points of the approximal surfaces) and the buccolingual crown diameter (the greatest distance at a right angle to the mesiodistal measurement) were obtained by using an electronic digital caliper. Significant differences between antimeres were found in the mesiodistal diameters of maxillary canine and maxillary molars (p < 0.001) as well as in the buccolingual diameters of mandibular molars (p < 0.05). Excellent correlations between the antimeres of the corresponding teeth were found (r = 0.70 to 0.96). Boys generally had larger crown diameters than girls with the exception of mesiodistal diameters of maxillary and mandibular canines, and mandibular lateral incisor, whereas the statistically significant gender difference was only found in the buccolingual diameter of mandibular second molar (p < 0.05). The higher the percentage of sexual dimorphism, the larger the gender differences. The percentage of sexual dimorphism ranged from 0.09 to 1.94 for mesiodistal diameters and 0.04 to 2.86 for buccolingual diameters. The mandibular second molar was the most dimorphic tooth. Variations in the crown diameters of the deciduous teeth existed among and within different populations. Deciduous mesiodistal crown diameters of Taiwanese were, in general, smaller than those of Australian aborigines, Taiwan Chinese aborigines, and Hong Kong Chinese, but larger than those of American whites. When considering the buccolingual crown diameters, our data were significantly smaller than those of Icelanders, western Indians, and whites.

Melanotic neuroectodermal tumour of infancy in the maxilla: a case report.

A 4.5-month-old Chinese boy presented with a bulging mass in the anterior right maxillary region. Clinical features and incisional biopsy examination confirmed the diagnosis of melanotic neuroectodermal tumour of infancy (MNTI). The lesion had first been noted a month before the biopsy. The extent of the lesion was defined via computed tomography, and surgical excision was accomplished through a partial maxillectomy under general anaesthesia. The patient has been irregularly followed-up over the past 8 years, and no evidence of recurrence has been found, either by clinical examination or serial computed tomography scans. A bony defect and a lack of alveolar process were noted on the right side of the anterior maxilla. The patient displayed social withdrawal at school as a result of his partial anodontia. There have only been a limited number of reports on the dental rehabilitation of postoperative MNTI. We report a case of maxillary MNTI in which the need for dental rehabilitation was emphasized.