Lihong Ge

Peking University School of Stomatology, Peping, Beijing, China

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Publications (14)22.99 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Purpose: To determine the effect of mechanical tooth cleaning by toothbrush and dental floss on mutans streptococci in the saliva of preschool children. Materials and Methods: This blinded, randomised controlled clinical trial included 54 3-year-old preschool children with detectable mutans streptococci in saliva. The children were randomly divided into a test and a control group. Dental college students cleaned the teeth of test group participants with toothbrush and dental floss under the indication of a plaque disclosing agent once a day. The control group received no intervention. Dentocult SM Strip mutans (D-SM) strips were used to test the mutans streptococci in saliva. Results: The D-SM test scores declined from 1.82 to 0.95 for the test group after the teeth were cleaned 10 times (P < 0.001) and the scores increased to 1.62 after tooth cleaning ceased for 2 weeks (P > 0.05 compared with baseline). The D-SM level of the control group did not change significantly. Conclusion: Meticulous and continuous plaque control with toothbrush and dental floss can decrease the mutans streptococci level in preschool children. However, the effect ceased as the intervention ceased.
    Oral health & preventive dentistry 06/2014; · 0.52 Impact Factor
  • Haihua Lei, He Liu, Yun Ding, Lihong Ge
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    ABSTRACT: Recent studies have reported that supernumerary teeth were observed in the maxillary incisor area in several Pax6 homozygous mutant mouse and rat strains. To date, it remains unknown whether Pax6 is expressed during tooth development in any species. The study aimed to analyze the expression of Pax6 during mouse incisor and molar development. C57BL/6J mouse embryos on days E12.5, E13.5, E14.5, E16.5 and E18.5 were produced. Heads from these embryos, as well as from P1.5 mice, were processed for paraffin wax embedding (N ≥ 3 for each stage) and prepared for immunohistochemistry. Pax6 immunostaining was found in all tooth germs examined. At the E12.5 dental placode, E13.5 bud stage, E14.5 cap stage and E16.5 early bell stage, Pax6 was expressed in ectodermally derived tissues of tooth germs and oral epithelia adjacent to the tooth germs. Cells in the underlying dental ectomesenchyme that showed Pax9 expression were Pax6 negative. At E18.5 and P1.5, Pax6 was expressed in more differentiated ameloblasts and cells of the stratum intermedium and stellate reticulum that were derived from the oral epithelium, as well as in mesenchyme-derived differentiated odontoblasts. Pax6 expression was also observed in the submandibular gland, tongue filiform papilla and hair follicle at E16.5 and P1.5. The present study demonstrated that Pax6 was expressed in incisor and molar germs during mouse tooth development. The results provide a basis for exploring the function of Pax6 during tooth development.
    Journal of molecular histology 01/2014; · 1.75 Impact Factor
  • Yu Wang, He Liu, Lihong Ge
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    ABSTRACT: To evaluate the effect of modified Nance arch appliance in the treatment of ectopic eruption of maxillary first permanent molar. Thirty children with unilateral ectopic eruption of maxillary first permanent molar were treated with modified Nance arch appliance. The mesial angle of the maxillary first permanent molars and the magnitude of the primary second molar distal root lesion before and after treatment were measured on the panoramic radiographs and analyzed statistically. All 30 children completed the treatment. The mesial angle of the ectopic side significantly changed from (75.2 ± 7.6) ° before the treatment to (92.9 ± 5.2) ° after the treatment (t = -11.082, P < 0.05). The root lesion of the ectopic side significantly enlarged after the treatment, but there was no significant change on the normal side. The treatment of ectopic eruption of the maxillary first permanent molar using modified Nance arch appliance was successful. The attention should be paid to the magnitude of the primary second molar distal root lesion before and after treatment and it is suggested to start the treatment when mild root resorption appears.
    Zhonghua kou qiang yi xue za zhi = Zhonghua kouqiang yixue zazhi = Chinese journal of stomatology 01/2014; 49(1):32-6.
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    ABSTRACT: To investigate the influence of digit-sucking habit on palatal features in pre-school children by using a laser scanning system. Forty pre-school children were chosen according to the results of questionnaires, among which 20 with digit-sucking habit(digit-sucking group) and 20 without any oral habits(control group). Impression of the upper jaw was taken from each child. After laser scanning the plaster casts, and three-dimensional reconstruction by the computer, parameters of anterior and posterior palatal length, width and height were measured, ratios of height/width, length/width and width ratio of anterior and posterior palatal were analyzed. The differences of palatal features between two groups were analyzed by t test. There was statistical significance between digit-sucking group and control group in posterior palatal width, anterior palatal length and anterior palatal height. The ratios of height/width and length/width in both posterior and anterior areas were statistically significant (P < 0.05). Compared to the control group, the results indicated that palatal features were relatively deeper, narrower and more protrusive in digit-sucking group. The digit-sucking habit may have some deleterious impacts on the palatal features in pre-school children with primary dentition. And it is practical to measure the spacial palatal features by using laser scanning system to some extent.
    Hua xi kou qiang yi xue za zhi = Huaxi kouqiang yixue zazhi = West China journal of stomatology 08/2013; 31(4):393-6.
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    ABSTRACT: To investigate the pulp prognosis and influence factors of dentin-fractured teeth. Case records of dentin-fractured teeth treated with indirect pulp capping and with more than 2 years follow-up were collected. The data related to trauma information and pulp prognosis were recorded and the influence factors were analyzed by Logistic regression. This study consisted of 205 cases with 242 dentin-fractured teeth. Among 242 teeth, pulp necrosis occurred in 78 teeth(32.2%) and pulp calcification occurred in 3 teeth(1.2%). The success rate of indirect pulp-capping on dentin-fractured teeth was 67.8%. During observation period, 141 out of 177 young permanent teeth completed root development. The extent of fracture close to pulp was an indicator for pulp prognosis (P=0.001). The prognosis of indirect pulp-capping on dentin-fractured permanent teeth is good. The extent of fracture close to pulp should be considered to evaluate the prognosis of the pulp.
    Hua xi kou qiang yi xue za zhi = Huaxi kouqiang yixue zazhi = West China journal of stomatology 06/2013; 31(3):275-8.
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    ABSTRACT: The health of human teeth depends on the integrity of the hard tissue and the activity of the pulp and periodontal tissues, which are responsible for nutritional supply. Without the nourishing of the pulp tissue, the possibility of tooth fracture can increase. In immature permanent teeth, root development may be influenced as well. This study explored the potential of using autologous dental pulp stem cells (DPSCs) to achieve pulp regeneration in a canine pulpless model. The establishment of the pulpless animal model involved pulp extirpation and root canal preparation of young permanent incisor teeth in beagles. Autologous DPSCs were obtained from extracted first molars and expanded ex vivo to obtain a larger number of cells. The biological characteristics of canine DPSCs (cDPSCs) were analyzed both in vitro and in vivo by using the same method as used in human DPSCs. cDPSCs were transplanted into the pulpless root canal with Gelfoam as the scaffold, and root development was evaluated by radiographic and histologic analyses. cDPSCs with rapid proliferation, multiple differentiation capacity, and development potential were successfully isolated and identified both in vitro and in vivo. After they were transplanted into the pulpless root canal with Gelfoam as the scaffold, DPSCs were capable of generating pulp-like tissues containing blood vessels and dentin-like tissue. Thickening of the root canal wall was also observed. This study demonstrates the feasibility of using stem cell-mediated tissue engineering to realize pulp regeneration in immature teeth.
    Journal of endodontics 02/2013; 39(2):195-201. · 2.95 Impact Factor
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    ABSTRACT: Dens invaginatus is a rare developmental malformation of a tooth caused by the invagination of the tooth crown before biological mineralization occurs. The complex anatomy of these teeth makes nonsurgical endodontic treatment difficult and more so when there is presence of periapical periodontitis with open apex. The endodontic treatment of dens invaginatus is a challenge, especially in the case of periapical periodontitis with open apex. Pulp revascularization is a conservative endodontic treatment that has been introduced in recent years. Presented here is a variant approach for the treatment of immature dens invaginatus type II with periapical periodontitis, which combines filling of the invagination and pulp revascularization. After accessing the pulp chamber, the main canal and the invagination were explored. The root was thoroughly disinfected by irrigating and medication, invagination was filled, and the main canal was revascularized. Then the coronal sealing was made by glass ionomer cement and composite resin. Radiograph taken regularly and computed tomography scan were used to investigate the healing of the periapical lesion and development of the root. In the subsequent follow-up, the periapical lesion was completely eliminated, the open apex was closed, and the wall of the root was thickened. For type II immature dens invaginatus with large periapical lesion, conservative endodontic treatment should be considered before periapical surgery. With sufficient infection control, pulp revascularization can be an effective alternative method.
    Journal of endodontics 02/2013; 39(2):288-92. · 2.95 Impact Factor
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    ABSTRACT: Cyclin D1 (CCND1) plays a critical role in the G1 to S-phase cell cycle transition. Data on the association between the CCND1 A870G polymorphism and oral cancer are conflicting. To assess the relationship between the CCND1 A870G genotype and the risk of developing oral cancer, we performed a meta-analysis. We searched PubMed to December 1, 2011, for studies on this topic that had been published in the English. For each study, we calculated odds ratios (ORs) and 95 % confidence intervals (CIs), assuming the frequency of allele comparison, homozygote comparison, recessive and dominant genetic models. We then calculated pooled ORs and 95 % CIs. Seven studies were included in the meta-analysis. The CCND1 G allele was not associated with oral cancer in the frequency of allele comparison (G vs. A: OR = 0.882; 95 % CI = 0.684-1.137; p = 0.001 for heterogeneity). In the subgroup analysis, the CCND1 G allele was associated with a borderline significantly decreased risk of developing oral cancer in Asians in the frequency of allele comparison (G vs. A: OR = 0.800; 95 % CI = 0.636-1.006; p = 0.089 for heterogeneity), and the association between the GG genotype and oral cancer was significant in Asians with respect to both the homozygote comparison (GG vs. AA: OR = 0.644; 95 % CI = 0.491-0.843; p = 0.186 for heterogeneity) and the dominant genetic model (GG + AG vs. AA: OR = 0.713; 95 % CI = 0.584-0.870; p = 0.293 for heterogeneity). Our analysis provides evidence that genotypes for the CCND1 A870G polymorphism may be associated with an increased risk of developing oral cancer in the Asian population.
    Molecular Biology Reports 10/2012; · 2.51 Impact Factor
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    ABSTRACT: The aim of the present study is to investigate the prognosis and influencing factors of crown-fractured young permanent teeth with pulp exposure. Case records of crown-fractured young permanent teeth with pulp exposure in the Department of Pediatric Dentistry, Peking University School and Hospital of Stomatology during 1991 to 2008 with more than 2 years follow-up were collected. These patients were treated with pulpotomy at the first visit at our hospital no matter whether these teeth were treated or untreated with direct pulp capping. The age of patients, interval between trauma and treatment, root development, mobility and tenderness to percussion were recorded. The prognosis was analyzed and Logistic regression was used to analyze the influencing factors. Totally 118 cases satisfied the inclusion criteria, including 136 crown-fractured teeth with pulp exposure. The patients of (8.8 +/- 1.2) years old were periodically monitored for (46.1 +/- 22.0) months. The success rate of pulpotomy after pulp exposure was 85.3%. Pulp necrosis occurred in 20 teeth (25.0 +/- 19.0) months after trauma. The extent of tenderness to percussion showed significant correlation with pulp necrosis, while the age of the patients, interval between injury and treatment, and mobility of the teeth were not related to pulp necrosis. The success rate of pulpotomy after pulp exposure is good. Tenderness to percussion is an important signal of pulp necrosis. There are no evidence about the relationship between the patient's age, interval between injury and treatment, mobility of the pulp-exposed teeth and the pulp prognosis.
    Hua xi kou qiang yi xue za zhi = Huaxi kouqiang yixue zazhi = West China journal of stomatology 12/2011; 29(6):622-5.
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    ABSTRACT: The most important events during the regulation of tooth development were inductive interactions between the epithelial and mesenchymal tissues. The expression of Pax9 had been shown to specifically mark the mesenchymal regions at the prospective sites of all teeth prior to any morphological manifestations. Here, we investigated the PAX9 gene as a candidate gene for hypodontia in five unrelated Chinese patients with tooth agenesis. Direct sequencing and restriction enzyme analysis revealed a novel heterozygous mutation c.480C>G (p.160Tyr>X, Y160X) in a patient who was missing 20 permanent teeth (the third molars excluded) and 6 primary teeth. The mutation was a nonsense mutation, leading to a premature stop codon in exon 2 of PAX9 gene. PCR analysis of complementary DNA from cultured lymphocytes of the affected individual could not indicate the complete degradation of the mutated transcript. Promoter reporter assays revealed reduced transcriptional activity of the mutated PAX9 protein suggesting that the severe phenotype may result from haploinsufficiency of PAX9. In another patient with 15 missing permanent teeth (the third molars excluded), we found the c.219insG mutation previously reported by Stockton.
    Mutagenesis 11/2011; 27(3):313-7. · 3.50 Impact Factor
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    ABSTRACT: To evaluate the efficacy of laser fluorescence (LF) device in detecting approximal caries in primary molars. Two hundred and sixteen primary molars from 96 children were inspected visually to identify possible caries with contact approximal surfaces. Target molars and their contralateral molars were examined using bitewing radiographs (BR) and LF. Depending on the examination findings, invasive treatments were performed on molars to identify the presence of cavitation. Of 256 surfaces evaluated from 216 primary molars, 128 were intact, 39 had white spots, and 89 had cavities. At the white-spot threshold, sensitivity and specificity, respectively, were 2.56% and 94.87% for visual inspection (VI); 64.10% and 97.43% for BR; and 56.41% and 94.87% for LF. At the cavity threshold, sensitivity and specificity, respectively, were 70.79% and 95.51% for VI; 97.75% and 93.26% for BR; and 92.14% and 97.75% for LF. Significant differences between intact surfaces and white spots, and white spots and cavities were shown through LF readings. Both LF and BR can detect cavitations on approximal surfaces of primary molars. LF could be an alternative to radiographs in detecting approximal caries in primary molars.
    International Journal of Paediatric Dentistry 09/2011; 22(2):132-8. · 0.92 Impact Factor
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    ABSTRACT: BACKGROUND.  The genotypic diversity of both Streptococcus mutans and Streptococcus sobrinus in children with different caries experience remains unclear. AIM.  To investigate the genotypic diversity of S. mutans and S. sobrinus in children with severe early childhood caries (SECC) and in caries-free (CF) children. METHODS.  Stimulated saliva of 87 SECC and 91 CF children aged 3-4 years was collected and submitted to cultivation, and MS colonies were enumerated. The genomic fingerprint analysis of S. mutans and S. sobrinus was carried out using AP-PCR. RESULTS.  One to five genotypes of S. mutans were colonized in an oral cavity of SECC and CF children; 85.5% SECC children and 57.9% CF children harboured more than one genotype of S. mutans. One to three genotypes of S. sobrinus were detected from each SECC child; 31.25% SECC children harboured more than one genotype of S. sobrinus. And one genotype was colonized in each CF child. S. mutans isolates from different individuals displayed distinctive DNA fingerprints. CONCLUSIONS.  DNA fingerprints of S. mutans and S. sobrinus isolates from 3- to 4-year-old children displayed genetic polymorphism, and S. mutans has greater genetic diversity than S. sobrinus. SECC children harboured more genotypes of S. mutans and S. sobrinus than CF children.
    International Journal of Paediatric Dentistry 06/2011; 21(6):422-31. · 0.92 Impact Factor
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    ABSTRACT: Cleidocranial dysplasia (CCD) is a dominantly inherited skeletal dysplasia caused by mutations in the osteoblast-specific transcription factor-encoding gene, RUNX2. To correlate different RUNX2 mutations with CCD clinical spectrum, we studied six independent Chinese CCD patients. In five patients, mutations were detected in the coding region of the RUNX2 gene, including two frameshift mutations and three missense mutations. Of these mutations, four were novel and one had previously been reported. All the detected mutations were exclusively clustered within the Runt domain that affected conserved residues in the Runt domain. In vitro green fluorescent protein fusion studies showed that the three mutations--R225L, 214fs and 172fs--interfered with nuclear accumulation of RUNX2 protein, while T200I mutation had no effect on the subcellular distribution of RUNX2. There was no marked phenotypic difference between patients in craniofacial and clavicles features, while the expressivity of supernumerary teeth in our patient cohort had a striking variation, even among family members. The occurrence of intrafamilial clinical variability raises the view that hypomorphic effects and genetic modifiers may alter the clinical expressivity of these mutations. Our results provide new genetic evidence that mutations involved in RUNX2 contribute to CCD.
    Mutagenesis 11/2010; 25(6):589-94. · 3.50 Impact Factor
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    H Liu, J Li, H Lei, T Zhu, Y Gan, L Ge
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    ABSTRACT: Hypophosphatasia is caused by mutations of the tissue-non-specific alkaline phosphatase (TNSALP) gene with deficiency of dentin structure. The aim of this study was to examine whether TNSALP mutation in dental pulp cells contributes to dentin dysplasia in hypophosphatasia. Mutation analysis showed that compound heterozygous mutations of TNSALP were identified in three hypophosphatasia patients, including 3 novel mutation sites. Exfoliated teeth from the patients showed abnormal dentin mineralization and loss of cementum, as assessed by ground sections and scanning electron microscope analysis. Dental pulp cells isolated from one of the patients showed a significantly reduced TNSALP activity and mineralization capacity when compared with those in dental pulp cells from the unaffected individuals. Our results suggested that dentin dysplasia in hypophosphatasia may be associated with the decreased mineralization ability of dental pulp cells.
    Journal of dental research 10/2010; 89(12):1373-7. · 3.46 Impact Factor