Teeth under High Occlusal Force may Reflect Occlusal Trauma-associated Periodontal Conditions in Subjects with Untreated Chronic Periodontitis.

OBJECTIVE: To determine the association of high occlusal force (HOF) with the signs of occlusal trauma and periodontal conditions in periodontitis patients, and elaborate the relevant clinical implications. METHODS: Periodontal parameters and signs of occlusal trauma were recorded for 807 teeth in 30 subjects with untreated chronic periodontitis. The T-scan II occlusal analysis system determined the HOF during maximum intercuspation, lateral excursion and protrusive excursion. The correlation of HOF with periodontal parameters and signs of occlusal trauma was analysed. RESULTS: Overall, the teeth with HOF existed mainly in molars and presented with deeper probing depth (PD) and higher frequency of bleeding on probing (BOP) than those without HOF. The fixed-effect analysis showed that HOF was positively correlated with PD and BOP (P < 0.05) in posterior teeth; widened periodontal ligament space on radiographs in upper (r = 0.179, P < 0.01) and lower posterior teeth (r = 0.205; P < 0.05); as well as functional mobility in upper posterior teeth (r = 0.168; P < 0.05). CONCLUSION: This study suggests that the posterior teeth with HOF in subjects with chronic periodontitis may reflect occlusal trauma-associated periodontal conditions that could probably increase the risk of further periodontal destruction. These findings may improve the clinical assessment of occlusal trauma and related periodontal conditions for better patient management and treatment outcomes.

Effect of glycine powder air-polishing as an adjunct in the treatment of peri-implant mucositis: a pilot clinical trial.

BACKGROUND: Glycine powder air-polishing (GPAP) has the potential to effectively erase biofilms and may improve the treatment efficacy of peri-implant mucositis. This pilot clinical trial evaluated the effect of GPAP as an adjunct in treating peri-implant mucositis. MATERIALS AND METHODS: Twenty-four subjects having at least one implant with peri-implant mucositis were randomly assigned to test (12 subjects with 17 implants) and control (12 subjects with 16 implants) groups. Following baseline assessment, all subjects received oral hygiene instruction and non-surgical debridement. In the test group, the sites with probing depth (PD) ≥4 mm were additionally treated by GPAP for 5 sec. Clinical parameters were measured at 1-week, 1-month, and 3-month recall visits. RESULTS: At the 3-month visit, the mean reductions in PD at site level were 0.93 ± 0.93 mm and 0.91 ± 0.98 mm in the test and control groups, respectively (P < 0.05), and no significant difference existed between two groups. Mean bleeding score was also significantly reduced in both groups after the intervention. No complications or discomfort were reported during the study. CONCLUSIONS: This pilot clinical trial suggests that non-surgical mechanical debridement may effectively control peri-implant mucositis, and adjunctive GPAP treatment seems to have a limited beneficial effect as compared with mechanical debridement alone. However, further clinical trials with a large sample size are needed to confirm this preliminary observation.

[Longitudinal genetic effect on incisor position in cephalograms of female twins from six to twelve years old].

PURPOSE: A better understanding of the relative effect of genes and environment on craniofacial parameters should improve the possibilities and limitations of the orthodontic treatment and treatment planning. This is especially important for early treatment started in the mixed dentitions that is performed to enhance the dental and skeletal development before the eruption of the permanent dentition. METHODS: The sample used in this study consisted of lateral cephalograms of eighty-nine pairs of female twins in Beijing. With a mixed longitudinal method, the effective twins were 183 pairs (MZ 110, DZ 73). With the statistical methods of twins, the genetic and environmental effects were analyzed on the position of incisors in female twins from six to twelve years old. SPSS13.0 software package was used for independent-sample t test. RESULTS: Statistical comparisons revealed significant environmental effects on 6 positions of incisors (P<0.05), whilst family genetic effects on angle LI-MP were significant (P<0.05). CONCLUSION: Although the relatively low inherited proportions of dental variations could be found, genetic effects on incisor position should be carefully treated. Supported in part by a Grants-in-Aid for Scientific Research (International Scientific Exchange, 1994-1996) from the Japanese Ministry of Education, Culture, Science & Technology.

[Evaluation of the in vitro quantitative measurement of II degree furcation involvements in mandibular molars by cone-beam computed tomography].

OBJECTIVE: To evaluate the accuracy of measurement of II degree furcation involvements in molars of dry mandibles by cone-beam computed tomography (CBCT). METHODS: Twenty molars with II degree furcation involvements in dry mandibles were examined directly and measured by CBCT. Eight parameters were selected to describe the exact appearance of each II degree furcation involvements, including vertical defect dimensions, horizontal defect dimensions and furcation entrance dimensions. The results were compared with the corresponding data obtained by probing and periapical radiograph. RESULTS: All furcation involvements could be correctly classified by CBCT. For 5 of 8 parameters, no significant difference was found between the data obtained by CBCT and probing measurements (P>0.05). The distances from furcation entrance to alveolar crest, to bottom of bone pocket, and to the deepest site of horizontal bone defect measured by CBCT were less than those probed directly (P<0.05), but the differences were less than 0.5 mm (0.21, 0.24, 0.35 mm, respectively). The localization of furcation entrance may cause the differences. Two out of 20 furcation involvements could not be detected on periapical radiographs, and only 2 of 8 parameters could be measured on periapical radiographs. CONCLUSION: CBCT could provide precise and detailed 3D images of II degree furcation involvements in vitro.

[Association of Fc gamma receptors IIIA gene polymorphisms with the susceptibility to periodontitis in Chinese patients].

OBJECTIVE: Fc gamma receptors IIIA (Fc gamma RIIIA) mediates phagocytosis by macrophages, and cytokine production by NK cells and lymphocytes. The Fc gamma R IIIA-158V/F polymorphism may play a role in the pathogenesis of periodontitis. This study was to detect Fc gamma R IIIA-158V/F genotypes in Chinese patients with different forms of periodontitis. METHODS: Thirty aggressive periodontitis (AgP) patients (aged from 9 to 40, 13 males and 17 females), 131 chronic periodontitis (CP) patients (aged from 22 to 63, 76 males and 55 females), and 47 healthy subjects (H) (aged from 22 to 75, 21 males and 26 females) consented to participate in this study. Swabs were taken from each subject by ten strokes on the buccal mucosa. DNA was isolated from each swab by Chelex-100 methods. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP)was performed to determine the Fc gamma R IIIA-158 genotypes in each groups of subject. RESULTS: The allele frequency was in Hardy-Weinberg equilibrium in our cohort for the V-158F polymorphism in Fc gamma R IIIA gene (P>0.05). The detected frequency of 158F/F in AgP patients was significantly higher than that in CP patients (16.7% vs 0.8%, P<0.05), and also higher than that in H subjects (16.7% vs 4.3%) but was not statistically significant. No significant difference in distribution of the Fc gamma R IIIA-158V/F genotype was found between CP and H groups (P>0.05). CONCLUSION: The distribution of Fc gamma R IIIA-158F/F genotype might have effects on the phenotypes of periodontitis.

[The effect of different concentrations of platelet-rich plasma on human periodontal ligament cells in vitro].

PURPOSE: To assess the effect of different concentrations of platelet-rich plasma (PRP) on cell proliferation and alkaline phosphatase (ALP) activity of human periodontal ligament cells (hPDLCs) in vitro. METHODS: PRP was obtained from volunteer donors using two-step centrifugation. TGF-beta1 and PDGF-AB levels in activated PRP, PRP and plasma were evaluated by enzyme-linked immunosorbent assay. hPDLCs were exposed to various concentrations of PRP (2%,5%,10% and 20%) and DMEM (negative control), respectively. After 24 and 72 hours, cell proliferation was evaluated using Cell Counting Kit-8 assay. Alkaline phosphatase (ALP) activity of hPDLCs was evaluated by a p-nitrophenyl phosphate disodium assay. Statistical analysis was performed using one-way ANOVA and Student's t test in SPSS10.0. RESULTS: TGF-beta1 and PDGF-AB levels were highest in activated PRP. The effect of various concentrations of PRP on cell proliferation and ALP activity was significantly greater than that of negative control (P<0.001). The effect of PRP was significantly greater at 72-hour compared with that at 24-hour (P<0.01), with significantly difference among various PRP concentrations (P<0.001). Cell proliferation and ALP activity increased when the concentration of PRP increased from 2% to 10%. The maximum effect on cell proliferation was achieved with 10% PRP; 20% PRP resulted in a reduced cell proliferation. However, ALP activity was greatest with 20% PRP. CONCLUSION: PRP preparations exert a dose-dependent effect on hPDLCs proliferation and ALP activity in a certain extent in vitro at 24-hour and 72-hour. Supported by the Capital Medical Development Fund (Grant No. 2005-2007).

[Construction of 3D complex of porous beta-tricalcium phosphate/collagen scaffolds and dog periodontal ligament cells].

OBJECTIVE: To investigate the construction of 3D complex of porous beta-tricalcium phosphate/collagen scaffolds (beta-TCP/col) and dog periodontal ligament cells (PDLCs). METHODS: Dog PDLCs were isolated, cultured and identified. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay was used to evaluate the cytotoxicity of beta-TCP/col on the proliferation of PDLCs. The cells were seeded onto porous beta-TCP/col scaffolds. The cellular capability of adhesion and growth on porous beta-TCP/col surface was investigated visually by scanning electron microscopy (SEM). RESULTS: The cytotoxicity assay indicated that there was no significant difference between beta-TCP/col and the control during the 7 days (P>0.05). SEM showed cells successfully adhered to porous beta-TCP/col scaffolds and spread extensively. Matrix secretions were found on the cell surface. CONCLUSION: Porous beta-tricalcium phosphate/collagen scaffolds were of good biocompatibility to the dog periodontal ligament cells, and were potential ideal candidates for periodontal tissue engineering.

[Effect of verapamil on the proliferation of normal gingival fibroblast].

OBJECTIVE: To evaluate the effect of verapamil on the proliferation of normal gingival fibroblast (NGF) in vitro. METHODS: NGF was isolated and cultured. The 5th passage of NGF was incubated with 0, 0.1, 1, 10, 100 micromol/L verapamil respectively. Methyl thiazolyl tetrazolium (MTT) assay and flow cytometry were used to detect cell proliferation and cell cycles. RESULTS: Incubated with 100 micromol/L verapamil for 66 h, the A value of normal gingival fibroblast was significantly lower than those without verapamil groups (P < 0.01). Incubated with 100 micromol/L verapamil for 18 h, 69% of cells were at the G(0) - G(1) phase, 27% were at the S phase. For control group (without verapamil) 41% of cells were at G(0) - G(1) phase and 49% cells were at S phase. There was significant difference between the two groups (P < 0.001). CONCLUSIONS: 100 micromol/L verapamil inhibited proliferation of normal gingival fibroblast by a cell-cycle arrest.

[Novel mutations of cathepsin C gene in two Chinese patients with Papillon-Lefèvre syndrome].

OBJECTIVE: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

[Effects of enamel matrix protein on the growth of human periodontal ligament cells on root cementum surfaces].

OBJECTIVE: To evaluate the effect of enamel matrix protein (EMP) on the attachment and proliferation of periodontal ligament cells (PDLC) on diseased cementum surfaces in vitro. METHODS: Cementum chips were obtained from diseased roots exposed to periodontal pocket. Thirteen diseased root cementum chips were conditioned with EMP. Meanwhile, 13 diseased and 13 healthy cementum chips were treated with physiological saline as control. The growth and morphology of PDLC on the root surface were observed after 24 hours incubation by scanning electron microscope (SEM). PDLC attachment and proliferation were quantified using MTT assay at 16 or 72 hours. RESULTS: The cells on EMP treated roots under SEM were growing robust like the cells on healthy roots. By contrast, the diseased cementum surface without conditioned with EMP was only partly covered with spindle-shaped cells, with filopodia appearing short and thin. MTT assay indicated that the number of adhered and proliferated cells on diseased cementum chips treated with EMP was significantly greater than that on diseased chips treated with saline (adhesion: 0.45 +/- 0.03 vs. 0.37 +/- 0.05, P < 0.05; proliferation: 0.71 +/- 0.02 vs. 0.55 +/- 0.08, P < 0.01), but less than that on healthy chips (adhesion: 0.45 +/- 0.03 vs. 0.67 +/- 0.08, P < 0.05; proliferation: 0.71 +/- 0.02 vs. 1.05 +/- 0.09, P < 0.05). CONCLUSIONS: It was suggested that EMP could promote the growth of PDLC on the diseased root cementum surface.

[Comparative study of the effects of removing plaque by two toothbrushing methods].

OBJECTIVE: To compare the effects of removing plaque by two toothbrushing methods. METHODS: Forty subjects were chosen to take part in the randomized, examiner-blind, crossover study. RESULTS: Modified Bass method has better effect of removing plaque, especially that at the central margin than Vertical method (P<0.05). CONCLUSION: Modified Bass method needs to be recommended.

[The p16 methylation in oral leukoplakia and oral squamous cell carcinoma].

OBJECTIVE: To investigate p16 gene methylation in normal mucosa, leukoplakia with hyperplasia and dysplasia and oral squamous cell carcinoma. METHODS: 20 patients of leukoplakia with hyperplasia, 11 patients of leukoplakia with mild dysplasia, 10 patients of leukoplakia with moderate dysplasia, 9 patients of leukoplakia with severe dysplasia, 10 patients with OSCC in low grade, 12 patients with OSCC in moderate grade, 8 patients with OSCC in high grade, and 10 normal individuals were studied on p16 methylation. RESULTS: Rates of p16 methylation were 0 for normal individuals, 5% for patients of leukoplakia with hyperplasia, 18% for patients of leukoplakia with mild dysplasia, 10% for patients of leukoplakia with moderate dysplasia, 22% for patients of leukoplakia with moderate dysplasia, and 50% for patients with OSCC in low grade, 42% for patients with OSCC in moderate grade, and 63% for patients with OSCC in high grade. Rates of p16 methylation increased with tissue malignance increase and correlated positively to the tissue malignance. The rate (82%) of p16 methylation in OSCC patients with lymph node metastasis was significantly high than that (32%) of OSCC patients without lymph nodes metastasis. The methylated rates of p16 correlated positively to the lacking rates of p16 protein. CONCLUSIONS: It was first reported that p16 methylation occurred in every stage of leukoplakia cancerization and OSCC progression. p16 can be one of the important molecular biological markers for leukoplakia cancerization and OSCC progression. p16 methylation is recommended as an important marker for diagnosis of OSCC.