Single-cell transcriptome analysis reveals development atlas of mouse molar pulp cells / 中华口腔医学杂志

Objective: Single-cell RNA sequencing (scRNA-seq) was used to analyze the developing mouse molars, in order to construct a spatiotemporal development atlas of pulp cells, and further to reveal the developmental process and regulatory mechanism of tooth development. Methods: Ten mandibular first molars from C57BL/6 mice in postnatal day (PN) 0 and 3 were respectively dissected and digested to obtain single-cell suspensions. scRNA-seq was performed on 10× Genomics platform. PN 7 mouse molar scRNA-seq data were obtained from our previous study. PN 0, 3, and 7 scRNA-seq data were integrated for following analysis. The initial quality control, mapping and single cell expression matrix construction were performed by Cell Ranger. Quality control, standardization, dimensional reduction and cluster analysis were performed by using Seurat. Monocle was used to generate the pseudotime trajectory. Scillus was used to perform gene ontology analysis. In order to detect the spatiotemporal change of different population of pulp cells, the marker genes of each cluster were demonstrated by RNAscope in situ hybridization. Results: There were twenty-six cell clusters within mouse molars, which were identified as eight different cell types, including dental pulp cells, dental follicle cells, epithelial cells, immune cells, endothelial cells, perivascular cells, glial cells and erythrocytes. We further re-clustered and analyzed dental pulp cells. Cluster 0 were mature pulp cells, which located at the upper portion of crown. The main functions of cluster 0 were osteogenesis and extracellular structure organization. Cluster 1 were apical papilla cells, which located at the apical part of roots, whose main functions were extracellular structure organization and organ development. Cluster 2 were cycling cells, which were actively proliferated, resided in the lower portion of the crown. Cluster 3 and 4 were preodontoblasts and odontoblasts, respectively. Their functions were closely related to biomineralization. The proportion of mature pulp cells increased with the development process, while the proportion of cycling cells and odontoblast lineage decreased. According to the expression pattern of marker genes of each cluster, we constructed a cell atlas of dental pulp. Pseudotime trajectory analysis found there were two development trajectories within dental pulp. They both started from SPARC related modular calcium binding 2 (Smoc2)+ dental papilla cells, then went through DNA topoisomerase Ⅱ alpha (Top2a)+ cycling cells, and finally divided into coxsackie virus and adenovirus receptor (Cxadr)+ mature pulp cells or dentin sialophosphoprotein (Dspp)+ odontoblasts two lineages. Conclusions: scRNA-seq could fully discover the intercellular heterogeneity of cells on transcriptome level, which provides a powerful tool to study the process and regulatory mechanism of organ development.

Comparative study of differentiation potential of mesenchymal stem cells derived from orofacial system into vascular endothelial cells / 北京大学学报(医学版)

OBJECTIVE@#To compare the proliferation and capacity of differentiation to vascular endothelial cells and angiogenesis induction among stem cells from human exfoliated deciduous teeth (SHED), dental pulp stem cells (DPSC) and human bone marrow mesenchymal stem cells (BMSC) from orofacial bone.@*METHODS@#SHED and DPSC were isolated from pulp tissue of the patients. BMSC were isolated from orthognathic or alveolar surgical sites. The surface markers of the cells were detected by flowcytometry. Cell counting kit-8 (CCK-8) assays were conducted to detect the proliferation ability of the cells. The cells were induced into endothelial cells with conditional medium and then the induced cells were cultured in Matrigel medium. The expression of angiogenesis-related genes such as platelet endothelial cell adhesion molecule-1 (PECAM-1/CD31), vascular endothelial growth factor (VEGF), vascular endothelial growth factor receptor 1 (VEGFR1), vascular endothelial growth factor receptor 2 (VEGFR2) and von Willebrand Factor (vWF) were quantified by real-time PCR. The cells were cultured in chick embryo chorioallantoic membrane (CAM) and the vessels were counted after 5 days.@*RESULTS@#The cell surface markers CD73, CD90, CD105 and CD146 of all the stem cells were positive, CD34 and CD45 were negative. The CD146 positive rate of SHED and DPSC was higher than that of BMSC. SHED had a higher proliferation rate than DPSC and BMSC. After angiogenic induction for 14 d, 3 kinds of cells emanated pseudopodia formed grid structure long vasculature in Matrigel media. The total length of tube formation of induced BMSC (7 759.7 μm) and SHED (7 734.3 μm) was higher than DPSC (5 541.0 μm). The meshes number of induced SHED (70.7) was higher than DPSC (60) and BMSC (53.7) in Matrigel medium. The expression of CD31, VEGFR2 and vWF genes of SHED were higher than those of BMSC and DPSC. VEGFR1 gene expression of BMSC was higher than that of the other groups, and SHED was higher than DPSC. The expression of VEGF showed no difference among the cells. No deference was showed between the effect of the stem cells and negative control on new formed vessels in CAM. The total length of vessels of SHED (30.4 mm) was higher than that of the negative control (20.9 mm) and BMSC (28.0 mm).@*CONCLUSION@#SHED, DPSC and BMSC can differentiate into vascular endothelial cells. SHED showed a stronger angiogenesis differentiation and proliferation potential compared with DPSC and BMSC.

Comparison of the properties of CD146 positive and CD146 negative subpopulations of stem cells from human exfoliated deciduous teeth / 北京大学学报(医学版)

OBJECTIVE@#Stem cells from human exfoliated teeth (SHED) were sorted by magnetically activated cell sorting (MACS) technique to obtain the CD146 positive and negative cell subpopulation. Then the biological characteristics of these subpopulations were compared to explore their specific application potential in tissue engineering.@*METHODS@#In this study, freshly extracted deciduous teeth without any caries or dental pulp disease were obtained. SHED was isolated using enzyme digestion method and then sorted by MACS, CD146 positive cells and CD146 negative cells were obtained after cell sorting. The biological characteristics of the unsorted mixed cells, CD146 positive subpopulation and CD146 negative subpopulation were compared. The proliferation ability was detected through cell counting kit-8 (CCK-8) and colony-forming unit (CFU). After osteogenic induction, alizarin red staining was performed and the gene expression of osteogenic related markers was detected by quantitative real-time polymerase chain reaction(qPCR). After adipogenic induction, oil-red O staining was performed and the gene expression of adipogenic related markers was detected. After neurogenic differentiation induction, the expression of neural markers was detected by immunofluorescence and the gene expression of neural markers was detected by qPCR.@*RESULTS@#SHED of the fifth passage was sorted by MACS. And the CD146 positive cell subpopulation and CD146 negative cell subpopulation were obtained. CCK8 assay showed that the proliferative tendency of the three cell groups was consistent, but the proliferation potential of CD146 positive and negative cell subpopulations was significantly lower than that of the unsorted cells. The colony forming rates of the unsorted mixed cell group, CD146 positive and negative populations were 28.6%±3%,17.1%±2.3% and 27.5%±2.5%, respectively. After 21 days of osteogenic induction, alizarin red staining and qPCR showed that the CD146 positive cell population had more mineralized nodule formation and expressed higher level of osteogenic related genes compared with the other two groups. After 21 days of adipogenic induction, oil red O staining and qPCR results showed that the CD146 negative subpopulation produced more lipid droplets and the expression of lipid related genes increased more significantly. After 14 days of neural induction, cell immunofluorescence and qPCR results showed that the unsorted mixed cell group and CD146 positive subpopulation expressed glial cell marker, and the expressions of neural precursor cells and neuronal marker increased significantly in negative subpopulation.@*CONCLUSION@#The unsorted mixed cells showed better proliferative potential than CD146 positive and negative subpopulations. The CD146 positive subpopulation was most potent in osteogenic differentiation; it was more suitable for bone tissue engineering. The CD146 negative cells had stronger adipogenic differentiation potential than the other two cell groups; different subpopulations differed in neural differentiation.

Three-dimensional analysis of the early correction of anterior crossbite using eruption guidance appliance / 北京大学学报(医学版)

OBJECTIVE@#To investigate the clinical effect of eruption guidance appliance in the treatment of anterior cross bite in mixed-dentition children.@*METHODS@#In the study,10 mixed-dentition children with anterior cross bite, totally 12 incisors, were selected. Alginate was used to take upper and lower dentition impression and make a hard plaster model,which served as the eruption guidance appliance for treatment. The pre- and post-operative dental casts were digitized with SmartOptics Activity 880 scanner,and the three-dimensional overlapping models were obtained by reverse engineering software,Geomagic Studio 2012,then the three-dimensional movements of the upper and lower incisors were analyzed using Imageware 13.2 software. The overbite and overjet were analyzed using the same methods. Measurement with copper wire was used to analyze the upper and lower arch length. Space analysis was the result by the sum of crown width minus the arch length. The crown width of unerupted permanent teeth was according to X-ray method to predict. The SPSS 17.0 software was used to analyze the pre- and post-operative measurements of the same child. The normality test of the measured data showed that it conformed to the normal distribution. Therefore,the t test and double side test were used,and the significance level was 0.05.@*RESULTS@#The course of treatment was (5.6±2.7) months. During orthodontic treatment, the upper incisors moved mainly labially (P<0.001) in three-dimensional displacement, and the lower incisors moved mainly the same direction (P=0.025). During the treatment of eruption guidance appliance,the average overbite decreased (1.01±0.9) mm (t=-3.531, P=0.006), and the difference was statistically significant. There was no statistically significant difference between the pre- and post-operative average overjet (t=0.771, P=0.460). The severity of crowding in upper arch decreased (1.9±0.99) mm (t=-6.042, P<0.001),and that in lower arch decreased (1.9±0.74) mm (t=-8.143, P<0.001), both of the differences were statistically significant.@*CONCLUSION@#The anterior cross bite in mixed dentition could be corrected by eruption guidance appliance, and at the same time, the normal overjet and overbite were established, and the teeth were aligned.

Analysis of dental agenesis patterns of the oligodontia patients using the method of tooth agenesis code / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To analyze the common dental agenesis patterns of the oligodontia patients.</p><p><b>METHODS</b>The information of 64 oligodontia patients was collected, including the histories, oral examinations and panoramic radiographs. The Tooth Agenesis Code (TAC) procedure was used to analyze the agenesis pattern of each quadrant.</p><p><b>RESULTS</b>In the maxilla, 63% (40/64) (right side) and 58% (37/64) (left side) could be described using eight different patterns. The most common pattern was agenesis of the maxillary lateral incisor, canine and both premolars.In the mandible, 52% (33/64) (right side) and 53% (34/64) (left side) of the patients could be described using only five different patterns, the most common pattern was agenesis of both mandibular premolars.</p><p><b>CONCLUSIONS</b>Common patterns of tooth agenesis were successfully identified in non-syndromic oligodontia patients.</p>

Chinese version of a face version of the modified child dental anxiety scale: transcultural adaptation and evaluation / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To develop the Chinese version of a face version of the modified child dental anxiety scale (MCDASf) and test the reliability and validity of MCDASf.</p><p><b>METHODS</b>The English version of MCDASf was translated and back-translated, as well as crosscultural adapted by the method of psychometrics to develop the Chinese version of MCDASf. Subsequently the Chinese version schedule was randomly investigated among 245 kindergarten children and school children aged greater than 4 and less than 12 years on two separate occasions 3 weeks apart to determine the reliability. A total of 248 children attending Pediatrics Dentistry of Peking University School and Hospital of Stomatology aged greater than 4 and less than 12 years old were selected and completed the Chinese version of MCDASf and the Chinese version of modified Children's fear survey schedule-dental subscale (CFSS-DS) before treatment to determine the validity. Then we rated the children's behavior during dental treatment by Venham's clinical anxiety rating scale and cooperative behavior rating scale to evaluate the relation between self-assessed dental anxiety scores and the behavioral reaction during the dental treatment.</p><p><b>RESULTS</b>In reliability study, 98.0% of 250 children completed the MCDASf. In validity study, 99.2% of 248 children completed the MCDASf. Cronbach's alpha coefficient of the translated scale was 0.814 and the test-retest reliability was 0.907. Principal component analysis of the translated scale confirmed that the scale consisted of a single unidimensional construct. The Chinese version of MCDASf significantly was correlated with the Chinese version of modified CFSS-DS (r = 0.843, P < 0.01) . It was also correlated with Venham's clinic anxiety rating scale and cooperative behavior rating scale (r = 0.675, P < 0.01).</p><p><b>CONCLUSIONS</b>The Chinese version of MCDASf demonstrated good reliability and validity and can be used as a simple self-report measurement of dental anxiety in Chinese children aged 4-11 years.</p>

Isolation and identification of Beagle dog dental pulp stem cells / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To identify the existence of the dental pulp stem cells in Beagle's pulp tissue by using the same methods of isolating and culturing the human dental pulp stem cells.</p><p><b>METHODS</b>Pulp tissue was extirpated from the crown and root of the Beagle's healthy permanent tooth, and digested by dispase for cell culture. Classical identification methods of mesenchymal stem cells including observation of biological characteristics, capacity of multilineage differentiation, and expression of specific markers associated with mesenchymal stem cells were applied to verify the existence of Beagle's dental pulp stem cells.</p><p><b>RESULTS</b>A clonogenic, rapidly proliferative population of cells were isolated from Beagle' pulp tissue. Under the same culture condition, the Beagle's dental pulp stem cells had a significant higher colony-forming unit-fibroblast (CFU-F) formation rate (150 colony/10(4) cells) than the dental pulp cells derived from the human pulp tissue (60 colony/10(4) cells). These cells also had the multilineage differentiation ability. They could be induced to form mineralized nodules, lipid droplets and chondrocytes. Furthermore these cells expressed the mesenchymal stem cell markers including STRO-1, CD146, alkaline phosphatase, nestin, vimentin and cytokeratin-18.</p><p><b>CONCLUSIONS</b>There are dental pulp stem cells in the Beagle's pulp tissue.</p>

An experimental study on the penetration abilities of resin infiltration into proximal caries lesions in primary molars / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To compare the penetration abilities of resin infiltration into proximal lesions in primary molars with those of adhesive in vitro.</p><p><b>METHODS</b>Thirty-two extracted or exfoliated primary molars showing proximal white spot lesions were selected. Roots of the teeth were removed, and the crowns were cut across the white spot lesions perpendicular to the surface. Cut surfaces were examined (by stereo microscopy) and classified with respect to histological lesion extension (C1-C4): lesions confined to the outer half on enamel (C1), lesions confined to the inner half on enamel (C2), lesions confined to the outer half on dentin (C3), lesions extending into the inner half of dentin (C4). Corresponding lesion halves were etched for 120 s with 15% hydrochloric acid gel and were subsequently treated with either adhesive or resin infiltration. Specimens were observed with laser scanning confocal microscope (LSCM) in dual fluorescence mode. In confocal microscopic images, lesion depth and penetration depth of the resin infiltration or the adhesive in corresponding halves were measured, and penetration percentages were calculated respectively. Differences of the data between two groups were analyzed by Wilcoxon signed rank test. Variations of histological caries extensions were detected with Kruskal-Wallis H test.</p><p><b>RESULTS</b>At the same grading level (C1-C3) in histological caries extension, penetration depths of the resin infiltration group and the adhesive group were 240 (230, 260) µm vs 190 (150, 210) µm, 405 (300, 523) µm vs 180 (160, 200) µm, and 590 (430, 640) µm vs 180 (160, 200) µm respectively. There was significant statistical difference in the data between two groups (P < 0.05). Statistically significant difference in penetration depths of the resin infiltration group (at C1-C3) were found (P < 0.01). At the same grading level (C1-C3) in histological caries extension, percentage penetrations of the resin infiltration group and the adhesive group were [100.0% (96.2%, 100.0%)], [99.1% (95.7%, 100.0%)], [82.0% (81.1%, 92.2%)] and [79.2% (68.4%, 87.5%)], [41.8% (29.1%, 74.5%)], [30.2% (29.2%, 39.6%)], respectively. The difference between the above data was also significant (P < 0.05). Percentage penetrations of the resin infiltration group at C1 and C2 level was higher than those at C3 level (P < 0.05).</p><p><b>CONCLUSIONS</b>The resin infiltration is capable of penetrating almost completely into proximal lesions in primary molars.</p>

The role of pulp in the root resorption of primary teeth without permanent tooth germs / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the role of pulp in the root resorption of primary teeth without permanent tooth germs.</p><p><b>METHODS</b>The animal model without permanent tooth germs was established by surgery in Beagle dog. The root resorption was observed by taking periapical radiographs periodically. The samples of mandibular bone and pulp at different resorption stages were collected. The distribution of odontoclasts and the activating factor was analyzed by histological staining and semiquantitative reverse transcriptase polymerase chain reaction (RT-PCR). The role of pulp in the root resorption of primary teeth was tested by early pulpectomy.</p><p><b>RESULTS</b>In the root resorption of primary molars without permanent teeth germs, a large number of odontoclasts were present on the pulpal surface of the root canal. Semi-quantification RT-PCR showed that the ratios of the expression of receptor activator of NF-κB ligand (RANKL) mRNA and β-actin in the pulp of permanent teeth and primary teeth without permanent teeth germ during different periods of root resorption are 0.1314, 0.1901, 0.2111 and 0.6058 (P > 0.05). The root resorption of primary teeth without permanent teeth germs in test groups was about 5 weeks later than that of control group.</p><p><b>CONCLUSIONS</b>The pulp of primary tooth played an important role in the root resorption of primary tooth without permanent tooth germ.</p>

Dental anomalies in Chinese children with complete unilateral cleft lip and palate / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the prevalence of dental anomalies in Chinese children with complete unilateral cleft lip and palate (UCLP).</p><p><b>METHODS</b>Dental histories and radiographs of 244 Chinese children with UCLP were collected. The diagnosis of dental anomalies was based on panoramic radiographs before alveolar bone grafting. All patients were over 8 years old.</p><p><b>RESULTS</b>In the UCLP group, 66.8% of the patients was presented with hypodontia. The maxillary lateral incisors were the most common teeth affected, followed by maxillary second premolars, mandibular incisors and mandibular second premolars. A total of 33.6% the patients was presented with dental malformation, most were microdontic laterel incisors. A total of 4.9% the patients was presented with hyperdontia. The supernumerary teeth were more frequently found in the cleft region. The prevalence of missing maxillary lateral incisor in the noncleft side was statistically different between genders, which was higher in male (P < 0.050). This group of Chinese children with UCLP demonstrated significantly higher prevalence of hypodontia, hyperdontia, and malformation on the cleft side than on the noncleft side (P < 0.01).</p><p><b>CONCLUSIONS</b>Hypodontia is the most common type of dental anomalies. The prevalence of dental anomalies is higher in the UCLP patients than in the normal population. Dental anomalies occur more frequently on the cleft side than on the noncleft side.</p>

Right hepatic arterial pseudoaneurysm with hemobilia following minilaparotomy cholecystectomy: a rare complication

Hepatic arterial pseudoaneurysm with hemobilia occurs less frequently as a complication of minilaparotomy cholecystectomy than laparoscopic cholecystectomy; however, given its severe nature, it needs to be managed promptly. This report presents a case of right hepatic artery pseudoaneurysm with hemobilia in a 36-year-old woman who underwent minilaparotomy cholecystectomy 5 weeks earlier. Angiography with embolization was carried out as definitive treatment

Results of functional management of condylar fracture in 3 to 16 years old children / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the effect of soft occlusal splint in the treatment of condylar fracture in children and adolescents.</p><p><b>METHODS</b>Twenty-three children with condylar fracture aged from 3 to 16 were included in this study. Impressions of both jaws were taken and stone working models poured. After occlusion was recovered by mounting on a bionic articulator, a soft occlusal splint was fabricated. The occlusal splint was worn for 1 to 3 months accompanied with functional exercise. Follow-up was carried out by clinical observation and panoramic image.</p><p><b>RESULTS</b>Clinical satisfactory results were obtained in all the patients with good occlusion, unimpaired function and normal growth and development of the mandibles. Panoramic image showed reconstruction of the fractured condyles, which were flattened and short.</p><p><b>CONCLUSIONS</b>Soft occlusal splint is a promising approach for treating condylar fracture in children.</p>

Occurrence of supernumerary upper incisor teeth in Pax6-/- mouse fetuses / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the occurrence of supernumerary upper incisor teeth in Pax6-/- mouse fetuses and to provide a model to explore the role of Pax6 in the upper incisor development and the mechanism of supernumerary teeth involving Pax6.</p><p><b>METHODS</b>Twenty Pax6-/- mouse fetuses of strain DEBA were isolated on E18.5 (embryonic day). The fetuses were sectioned serially in coronal plane and stained with haematoxylin and erosion, then the presence of supernumerary teeth in the upper anterior area was examined histologically, and also the number, morphology and structure of lower incisor germs and the first and second molar germs in the maxilla and mandible were observed histologically. Eighteen E18.5 mouse fetuses of strain DEBA with Pax6+/+ genotype were used as control.</p><p><b>RESULTS</b>Of the 20 Pax6-/- fetuses examined, four possessed a single supernumerary tooth in the upper incisors' region. No supernumerary upper incisor teeth were observed in any of the 18 Pax6+/+ fetuses examined. In the regions of lower incisors and the first and second molars of the maxilla and mandible, no significant difference was observed between Pax6-/- and Pax6+/+ fetuses regarding the number, morphology and structure of tooth germs.</p><p><b>CONCLUSIONS</b>The results suggest that Pax6 played an important role in the development of upper incisor teeth in mice.</p>

Clinical analysis of simple hypodontia / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To compare and analyse the distribution and characteristic of born missing teeth.</p><p><b>METHODS</b>A total of 183 simple hypodontia patients was reviewed and statistically analysed.</p><p><b>RESULTS</b>There was no significant difference in the number of missing teeth between different sexs (P > 0.05), and there was also no significant difference in the number of missing teeth among different sites (maxilla, mandible or left and right sides) (P > 0.05). The mandibular second premolar was the most frequently missing tooth. The missing molars were more commonly seen in oligodontia patients who had six missing teeth or beyond than hypodontia patients with less than six missing teeth (P < 0.05).</p><p><b>CONCLUSIONS</b>Each hypodontia patient has his own clinical manifestation, and appropriate treatment should be planed accordingly for these patients.</p>

Establishment and evaluation of a scale method for rating children's behavior in dental clinic in China / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To establish and evaluate a scale method for rating children's behavior in dental clinic in China.</p><p><b>METHODS</b>DV records were taken for 210 children under 8-year-old, who visited the department of pediatric dentistry of Peking University School and Hospital of Stomatology during Jun to Aug in 2004. The Venham's clinic anxiety rating scale and cooperative behavior rating scale were translated into Chinese, and modified according to these records. Twenty-four pieces of records were selected randomly, and 11 pediatric dentists and assistants assessed the child behavior in the 24 records. The intraclass correlation coefficient (ICC) and Spearman's correlation coefficient (SCC), which denoted inter-rater reliability and intra-rater reliability, were calculated.</p><p><b>RESULTS</b>The ICC was 0.929 and the SCC was 0.963.</p><p><b>CONCLUSIONS</b>The scale has good inter-rater reliability and excellent intra-rater reliability, and it is competent for rating the children's behavior in dental clinic in China.</p>

Experimental study of compomer sealant with non-rinse conditioner used on permanent molar / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To compare the microleakage of compomer sealant with non-rinse conditioner and resin sealant with phosphoric acid (35%) by dye test and scanning electron microscope (SEM) observation.</p><p><b>METHODS</b>16 extracted third permanent molars were divided into 4 groups: Group I, non-rinse conditioner (NRC) + Prime & Bond NT + Dyract seal; Group II, phosphoric acid (35%) + Concise sealant; Group III, phosphoric acid (35%) + Dyract seal; Group IV, NRC + Prime & Bond NT + Concise sealant. The teeth were then coated with nail polish, placed in a 50% AgNO3 dye for 18 hours, and sectioned with a diamond saw. SEM observation was performed to evaluate microleakage in the teeth.</p><p><b>RESULTS</b>Silver nitrate penetration was found in each group. The percentage of microleakage in group I was higher than that in group II, and group IV was higher than that in group II (P < 0.01). The percentage of microleakage of resin sealant with phosphoric acid was lower than that in compomer sealant with NRC (P < 0.01). On SEM observation, resin tags and few gaps were found in groups with phosphoric acid. Some gaps and bubbles were found at the bottom of the fissures, particularly in the narrow fissures because of the failure of sealant penetration.</p><p><b>CONCLUSION</b>Resin sealant used with phosphoric acid was better than compomer sealant with NRC on microleakage.</p>

The relationship between early childhood caries and child temperament / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate the differences in temperament between children with early childhood caries (ECC) and an age-matched children without ECC.</p><p><b>METHODS</b>A total of 219 3-year-old children were selected in urban areas of Beijing, who were physically and mentally healthy. There were 109 children in ECC group, who had unfilled caries in 1 or more surfaces in primary maxillary anterior teeth, and 110 children without caries. The children were examined for ECC levels, and their parents were asked to complete the NYLS Temperament Scale questionnaire. Then the data was collected and analyzed.</p><p><b>RESULTS</b>Children with difficult, intermediate high or slow-to-warm-up temperament had more severe caries than children with easy or intermediate low temperament. There was a significant difference in temperament attribute "Activity level" between male children with ECC and without ECC. There was a significant difference in temperament attribute "Rhythmicity" between female children with ECC and without ECC.</p><p><b>CONCLUSIONS</b>There were some differences in temperament between 3-year-old children with ECC and without ECC in urban areas of Beijing.</p>

Novel mutations of cathepsin C gene in two Chinese patients with Papillon-Lefèvre syndrome / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the mutational characteristics of cathepsin C (CTSC) gene in two Chinese patients with Papillon-Lefèvre syndrome (PLS), and provide molecular basis for research of the pathogenesis of PLS.</p><p><b>METHODS</b>Peripheral blood samples were obtained from patients and their parents respectively. Genomic DNA were extracted after consents. Polymerase chain reaction, direct DNA sequencing and restriction enzyme reaction were performed to screen mutations of CTSC gene.</p><p><b>RESULTS</b>Compound heterozygous mutations of CTSC gene were identified in the two patients. Patient I carried the G139R and S260P mutations, patient II had the R250X and C258W mutations. The parents were heterozygous carriers without the clinical feature of PLS. None of the mutations were detected in normal controls. Furthermore, the S260P and C258W changes were novel mutations of CTSC gene, which had not been reported previously.</p><p><b>CONCLUSIONS</b>Mutations of CTSC gene are responsible for the phenotype of Papillon-Lefèvre syndrome in two Chinese patients. The results extend the mutation spectrum of CTSC gene and also provide basis for gene diagnosis of PLS in China.</p>

Risk factors of alveolar bone loss of primary teeth / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To study the risk factors of alveolar bone loss (ABL) of primary teeth in Chinese children.</p><p><b>METHODS</b>Caries, restoration, food impact, pulp pathosis, calculus, and periodontal status were examined in 106 children aged 3-10 years old. Bite-wing radiographs of posterior teeth were scanned into computer. The distance from the cemento-enamel junction to alveolar bone crest was measured from the mesial surface of the first primary molar to the distal surface of the second primary molar using Adobe Photoshop 5.0 image analyzing system. ABL was recorded if the distance was more than 2 mm and the lamina dura was absent. All patients were divided into ABL group and non-ABL group. All data were analyzed by SPSS 10.0.</p><p><b>RESULTS</b>Alveolar bone loss was found in 31 children (29%). Most of the affected areas were located at the proximal surface of primary molars. The mean of dmft and proximal dmft in ABL group were higher than those in non-ABL group (P < 0.01). Logistic regression also confirmed that proximal caries was high related factor. Inadequate restoration, and pulp pathosis were also related to alveolar bone loss in primary tooth.</p><p><b>CONCLUSION</b>In children, alveolar bone loss was mainly associated with local factors such as proximal caries, inadequate restoration, and pulp pathosis. Caries and pulp pathosis might be treated in time. Children with bone loss should be re-examined regularly.</p>

A study on initial colonization of Mutans streptococci on teeth in infants and toddlers / 华西口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the initial colonization of Mutans streptococci (MS) on teeth of children.</p><p><b>METHODS</b>Dental plaque was collected from 123 children aged from 7 to 42 months. MS was isolated by culturing on selective medium and identified by biochemical tests.</p><p><b>RESULTS</b>MS was detected in 51 of 123 children. The rate of colonization was 41.5%, and the mean age of colonization was 29 month. The incidence of MS infection increased with age and tooth eruption, and reached peak at 25 - 31 months, which was statistically significant. There was a correlation between infection of MS and dental caries.</p><p><b>CONCLUSION</b>The results indicate that the susceptive period of MS infection is from 25 to 31 months when the second primary molars erupt. MS infection is associated with dental caries.</p>