Exploration and practice of Peking University Model to improve the clinical teaching effect of clinical postgraduates majoring in periodontology / 中华口腔医学杂志

The number of patients with periodontal disease in China is large, and the ratio of doctors to patients is seriously imbalanced, especially in the insufficient number of periodontal specialists and periodontal teachers. Strengthening the cultivation of professional postgraduates in periodontology can effectively solve this problem. This paper summarizes the experiences of Peking University School and Hospital of Stomatology in the teaching of periodontal postgraduate students for more than 30 years, in cluding teaching objectives formulation, teaching resources allocation and enhancement of the quality control system of clinical teaching, for ensuring that the periodontal professional postgraduates could reach the expected level after training. This formed the current "Peking University Model". There are both opportunities and challenges in clinical teaching of periodontal postgraduates in domestic stomatology community. The authors hope that the continuous exploration and improvement of this teaching system will promote the vigorous development of clinical teaching for the postgraduates majoring in periodontology in China.

Multivariable analysis of tooth loss in subjects with severe periodontitis over 4-year natural progression / 北京大学学报(医学版)

OBJECTIVE@#To evaluate the characteristics of severe periodontitis with various number of tooth loss during 4-year natural progression, and to analyze the factors related to higher rate of tooth loss.@*METHODS@#A total of 217 patients aged 15 to 44 years with severe periodontitis were included, who participated in a 4-year natural progression research. Data obtained from questionnaire survey, clinical examination and radiographic measurement. Tooth loss during 4-year natural progression was evaluated. The baseline periodontal disease related and caries related factors were calculated, including number of teeth with bone loss > 50%, number of missing molars, number of teeth with widened periodontal ligament space (WPDL), number of teeth with periapical lesions and etc. Characteristics of populations with various number of tooth loss and the related factors that affected higher rate of tooth loss were analyzed.@*RESULTS@#In 4 years of natural progression, 103 teeth were lost, and annual tooth loss per person was 0.12±0.38. Nine patients lost 3 or more teeth. Thirty-four patients lost 1 or 2 teeth, and 174 patients were absent of tooth loss. Molars were mostly frequent to lose, and canines presented a minimum loss. The number of teeth with WPDL, with periapical lesions, with intrabony defects, with probing depth (PD)≥7 mm, with PD≥5 mm, with clinical attachment loss≥5 mm, with bone loss > 50% and with bone loss > 65% were positively correlated to number of tooth loss. Results from orderly multivariate Logistic regression showd that the number of teeth with bone loss > 50% OR=1.550), baseline number of molars lost (OR=1.774), number of teeth with WPDL (1 to 2: OR=1.415; ≥3: OR=13.105), number of teeth with periapical lesions (1 to 2: OR=4.393; ≥3: OR=9.526) and number of teeth with caries/residual roots (OR=3.028) were significant risk factors related to higher likelihood of tooth loss and multiple tooth loss.@*CONCLUSION@#In 4 years of natural progression, the number of teeth with bone loss > 50%, baseline number of missing molars, number of teeth with WPDL, baseline number of teeth with periapical lesions and number of teeth with caries/residual roots were significantly related to higher risk of tooth loss and multiple tooth loss among Chinese young and middle-aged patients with severe periodontitis in rural areas.

Role of growth arrest-specific protein 6 in migration and osteogenic differentiation of human periodontal ligament cells / 北京大学学报(医学版)

OBJECTIVE@#To investigate the role of growth arrest-specific protein 6 (Gas6) in the process of the migration and osteogenic differentiation of human periodontal ligament cells (hPDLCs).@*METHODS@#After different concentrations of recombinant human Gas6 (rhGas6) were added to hPDLCs, cell prolife-ration experiment (CCK-8) was taken to observe the effect of rhGas6 on hPDLCs cell proliferation. Scratch test and cell migration test (Transwell) were taken to analyze the migratory ability of hPDLCs in different concentrations of rhGas6 groups. After osteogenic induction, real-time quantitative polymerase chain reaction (real-time PCR) was taken to detect the expression of the Runt-related transcription factor 2 (Runx2) and alkaline phosphatase (ALP). ALP staining was used to detect the amount of mineralized nodules.@*RESULTS@#After adding different concentrations of rhGas6, there were no statistically significant differences in hPDLCs cell proliferation among the experimental groups and the control group at 24, 48 and 72 hours (P>0.05). After 24 h of scratch, the healing area in the 800 μg/L of the rhGas6 group was greater than that in the control group, but without statistically significant difference (31.06%±13.70% vs. 21.79%±9.51%, P>0.05). In the migration test, after 24 h, the number of hPDLCs cells which penetrated through the membrane in the 800 μg/L rhGas6 group was significantly higher than that in the control group (P < 0.01). After rhGas6 was added and osteogenic induction, Runx2 and ALP gene expressions of hPDLCs in the 800 μg/L group were significantly higher than those in the control group (1.60±0.30 vs. 0.91±0.10, 2.81±0.61 vs. 0.86±0.12, P < 0.01). After Gas6 was knocked down, the ALP expression of hPDLCs was significantly lower than that of the control group (0.39±0.07 vs. 0.92±0.14, P < 0.01). There was no significant change in Runx2 expression (P>0.05). After 7 days of osteogenic induction, the mineralized nodules formed in the Gas6 knockdown group were significantly less than those in control group (0.25±0.04 vs. 1.00±0.11, P < 0.001). After 14 days of induction, the staining degree of the Gas6 knockdown group was lower than that of the control group, but there was no significant difference (0.86±0.04 vs. 1.00±0.16, P>0.05).@*CONCLUSION@#After downregulation of Gas6 gene, mineralized nodule formation was reduced and ALP gene expressions were decreased in the early stage of osteogenic induction (7 days). After addition of rhGas6, Runx2 and ALP gene expressions were increased and the number of cell migration was increased, suggesting that Gas6 might play a promoting role in the migration and osteogenic differentiation of human periodontal ligament cells.

Gingival thickness assessment of gingival recession teeth / 北京大学学报(医学版)

OBJECTIVE@#To evaluate the gingival thickness and gingival biotype of gingival recession teeth of Chinese population.@*METHODS@#A total of 112 non-molar teeth with gingival recession in 34 patients were included. Direct measurement, cone-beam computerized tomography (CBCT) measurement and periodontal probe method were used to evaluate gingival thickness and biotype. Gingival thickness was measured at 2 mm apical to the gingival margin. Direct measurement was performed with a caliper of 0.01 mm resolution and anesthesia needles attached to silicone disk stops. Gingival biotype was assessed by sulcus probing, if the periodontal probe was visible through the gingival tissue, the gingival biotype was thin; If not visible, the gingival biotype was thick. The differences of gingival thickness among different gingival biotype, tooth site and gingival recession type were analyzed respectively. Besides, the results of CBCT measurement was analyzed compared with the direct measurement.@*RESULTS@#The average gingival thickness of non-molar recession teeth was (1.17±0.41) mm. The average gingival thickness of thick and thin biotype group were (1.38±0.4) mm and (0.97±0.30) mm, respectively, with statistically significant difference (P<0.001). The median of gingival thickness was 1.1 mm. Using 1.1 mm as the cut-off value of thick and thin gingival thickness group, the results matched well with the gingival biotype classification results by periodontal probe method (P=1.000). The average gingival thickness of maxillary teeth was significantly thicker than that of the mandibular teeth. They were (1.39±3.44) mm and (1.01±0.31) mm, respectively (P<0.001). The mean gingival thickness of MillerI, II and III degree gingival recession teeth were (1.15±0.34) mm, (0.83±0.17) mm and (1.26±0.56) mm, respectively, without statistically significant difference (P=0.205). The gingival thickness measurement results between CBCT method and direct measurement were without statistically significant difference (P=0.206).@*CONCLUSION@#In the non-molar gingival recession teeth, the cut-off value of gingival thickness to classify thick and thin biotype of Chinese population was 1.1 mm. The average gingival thickness of the maxillary teeth was significantly thicker than that of the mandibular teeth. Besides, CBCT measurement was an accuracy method for evaluating facial gingival thickness.

Vestibular incision subperiosteal tunnel access with connective tissue graft for the treatment of Miller classI and II gingival recession / 北京大学学报(医学版)

OBJECTIVE@#To evaluate the clinical outcomes of vestibular incision subperiosteal tunnel access (VISTA) with connective tissue graft (CTG) in the treatment of Miller classes I and II localized gingival recession.@*METHODS@#Ten patients with 10 Miller classes I and II localized gingival recessions were enrolled in the study. All defects were equal to or above 2 mm in recession depth. All the patients received treatment with VISTA+CTG. Their clinical parameters, including recession depth (Rec), recession width (RW), keratinized tissue width (KT), clinical attachment loss (CAL), probing depth (PD) were recorded and compared before surgery and 6 months later. The mean root coverage (MRC) and complete root coverage (CRC) were calculated at the end of 6 months. A visual analogue scale (VAS) was used to estimate the patients' discomfort during the operation and during the 2 weeks post-operation. Patient-based aesthetic satisfaction 6 months after surgery was evaluated by a VAS.@*RESULTS@#The mean Rec was (2.65±0.82) mm at baseline, and (0.35±0.58) mm after 6 months. The VISTA+CTG treatment resulted in an improvement of (2.30±0.98) mm in recession depth (P<0.001). MRC was 86.67%±21.94% and CRC reached 70% at the end of 6 months. KT increased (0.90±1.22) mm (P<0.05). Aesthetic satisfaction on the patients' level was 8.30 based on VAS (0=unsatisfied, 10=extremely satisfied). The patients' discomfort during the operation and 2 weeks post operation were 2.40 and 4.30 (0=no pain, 10=extreme pain). Furthermore, clinical outcomes showed no statistically significant difference between the gingival biotypes, and between the teeth positioned in maxillary and in mandibular.@*CONCLUSION@#VISTA+CTG could be an effective treatment for Miller classes I and II localized gingival recession. Clinical outcomes indicated decrease in recession depth and width, and increase in width of keratinized tissue. Patients suffered little pain during the operation and 2 weeks post-operation of healing and accessed good aesthetic satisfaction. VISTA+CTG could be an option for the treatment of Miller classes I and II localized gingival recession.

Role of vitamin K-dependent protein Gas6 in the expression of endothelial cell adhesion molecule-1 and chemokines induced by Porphyromonas gingivalis lipopolysaccharide / 北京大学学报(医学版)

OBJECTIVE@#Growth-arrest-specific protein 6 (Gas6) is a vitamin K-dependent protein and involved in cell proliferation, survival, adhesion and migration . Also it has been shown to play an important role in the inflammatory response .The aim of present study was to investigate the role of Gas6 in the process of the expression of adhesion molecules and chemokines of human umbilical vein endothelial cells (HUVECs) induced by Porphyromonas gingivalis lipopolysaccharide(P.g-LPS).@*METHODS@#After up-regulation and down-regulation of the expression of Gas6, the vascular endothelial cells were stimulated with 1 mg/L P.g-LPS for 3 h and 24 h. Real-time quantitative polymerase chain reaction(real-time PCR) was taken to detect the expression of the cell adhesion molecules:intercellular adhesion molecule-1 (ICAM-1) and E-selectin, as well as chemokines:interleukin-8 (IL-8) and monocyte chemoattractant protein 1 (MCP-1). Wound healing assay was taken to observe the migration ability of endothelium cells in different groups.@*RESULTS@#After 3 h of P.g-LPS stimulation, the expression of adhesion molecules and chemokine in the down-regulation group was not significantly different from that in the control group,while in the up-regulation group the decrease of E-selectin, ICAM-1, IL-8 and MCP-1 was 81%±0%, 47%±3%, 76% ± 3%, 26% ± 6% respectively. After 24 h of P.g-LPS stimulation, the expression of adhesion molecules and chemokine in down-regulation group was significantly higher than that in control group (2.06±0.07, 1.99±0.11, 3.14±0.15, 1.84±0.03 flod), while these molecules in the down-regulation group was significantly lower than in the control group (29%±1%, 62%±3%, 69%±1%, 41%±2%). Differences were statistically significant (P<0.01). Wounding healing assay showed that down-regulation of Gas6 enhanced migration ability of endothelial cells while up-regulation of Gas6 weakened this ability,which was consistent with the trend of real-time PCR result.@*CONCLUSION@#Down-regulation of the Gas6 gene enhanced the expression of ICAM-1, E-selectin, IL-8 and MCP-1 in HUVECs after P.g- LPS stimulating, while up-regulaiton of the Gas6 gene weakened the expression of ICAM-1, E-selectin, IL-8 and MCP-1 in HUVECs after P.g-LPS stimulating,suggesting that Gas6 may play a role in the process of endothelial cell adhesion.

Effect of initial periodontal therapy on chronic periodontitis patients with stable coronary heart disease / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the clinical results of initial periodontal therapy on chronic periodontitis patients with stable coronary heart disease.</p><p><b>METHODS</b>Thirty-two chronic periodontitis patients with stable coronary heart disease were included in this prospective study. All subjects received oral hygiene instruction, scaling and root planing and clinically monitored for 3 months. The clinical parameters, including plaque index (PLI), probing depth (PD), attachment loss (AL) and bleeding index (BI), were recorded at baseline and 3 months after treatment. Serum levels of high-sensitivity C-reactive protein (hs-CRP), cholesterol (CHO), triglyceride (TG), high-density lipoprotein (HDL), low-density lipoprotein (LDL) and glucose (GLU) were also measured.</p><p><b>RESULTS</b>At 3 months after initial periodontal therapy, the mean PD of patients reduced from (3.95 +/- 0.15) mm to (2.93 +/- 0.21) mm (P < 0.01), the mean AL from (3.08 +/- 0.43) mm to (2.43 +/- 0.37) mm (P < 0.01), the percentage of sites with PD > or =5 mm from (22.37 +/- 6.88)% to (3.00 +/- 1.80)% (P < 0.01). hs-CRP significantly decreased at 3 months after treatment compared with baseline [(2.71 +/- 2.69) mg/L vs. (1.99 +/- 2.14) mg/L, P < 0.05]. CHO,TG, HDL, LDL and GLU decreased slightly (P > 0.05).</p><p><b>CONCLUSIONS</b>Initial periodontal therapy is effective for chronic periodontitis patients with stable coronary heart disease. After initial periodontal therapy, periodontal parameters improved significantly and serum levels of hs-CRP decreased.</p>

Clinical evaluation on aesthetic outcome of anterior tooth restoration using crown lengthening surgery / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To evaluate methods and clinical performance of crown lengthening surgery for aesthetic restoration improvement of short anterior teeth. Various surgery methods, proper restoration time after surgery, and indications for crown lengthening surgery were discussed.</p><p><b>METHODS</b>Crown lengthening surgery and prosthetic treatment were applied to 148 short anterior teeth of 22 cases. Modified Ryge criteria were used to assess the gingival health after treatment. Restoration results before and after treatment were evaluated by use of Kay's altered dental esthetics classification.</p><p><b>RESULTS</b>When patients were re-examined after restoration of two weeks, obvious inflammation was found in 7.4% teeth. After providing the treatment and instruction on oral hygiene, 98.6% gingival health was significantly improved during the follow-up period. Two cases were examined during more than 4-year period and no obvious gingival inflammation and change in dental crown ratio were found. After treatment, all of 22 cases met Kay dental esthetics classification Class II-I (cosmetic) or Class II-I criteria.</p><p><b>CONCLUSIONS</b>Right selection of indications, accurate restoration design, delicate surgery operation, enough recover period for the gingival after surgery, and proper oral hygiene training method, all contribute to the satisfactory aesthetic restoration of anterior teeth.</p>

Effects of enamel matrix protein on the growth of human periodontal ligament cells on root cementum surfaces / 中华口腔医学杂志

<p><b>OBJECTIVE</b>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.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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).</p><p><b>CONCLUSIONS</b>It was suggested that EMP could promote the growth of PDLC on the diseased root cementum surface.</p>

Effect of platelet-rich plasma in the treatment of periodontal intrabony defects in humans / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Platelet-rich plasma (PRP) is a kind of natural source of autologous growth factors, and has been used successfully in medical community. However, the effect of PRP in periodontal regeneration is not clear yet. This study was designed to evaluate the effectiveness of PRP as an adjunct to bovine porous bone mineral (BPBM) graft in the treatment of human intrabony defects.</p><p><b>METHODS</b>Seventeen intrabony defects in 10 periodontitis patients were randomly treated either with PRP and BPBM (test group, n = 9) or with BPBM alone (control group, n = 8). Clinical parameters were evaluated including changes in probing depth, relative attachment level (measured by Florida Probe and a stent), and bone probing level between baseline and 1 year postoperatively. Standardized periapical radiographs of each defect were taken at baseline, 2 weeks, and 1 year postoperatively, and analyzed by digital subtraction radiography (DSR).</p><p><b>RESULTS</b>Both treatment modalities resulted in significant attachment gain, reduction of probing depth, and bone probing level at 1-year post-surgery compared to baseline. The test group exhibited statistically significant improvement compared to the control sites in probing depth reduction: (4.78 +/- 0.95) mm versus (3.48 +/- 0.41) mm (P < 0.01); clinical attachment gain: (4.52 +/- 1.14) mm versus (2.85 +/- 0.80) mm (P < 0.01); bone probing reduction: (4.56 +/- 1.04) mm versus (2.88 +/- 0.79) mm (P < 0.01); and defect bone fill: (73.41 +/- 14.78)% versus (47.32 +/- 11.47)% (P < 0.01). DSR analysis of baseline and 1 year postoperatively also showed greater radiographic gains in alveolar bone mass in the test group than in the control group: gray increase (580 +/- 50) grays versus (220 +/- 32) grays (P = 0.0001); area with increased gray were (5.21 +/- 1.25) mm(2) versus (3.02 +/- 1.22) mm(2) (P = 0.0001).</p><p><b>CONCLUSIONS</b>The treatment with a combination of PRP and BPBM led to a significantly favorable clinical improvement in periodontal intrabony defects compared to using BPBM alone. Further studies are necessary to assess the long-term effectiveness of PRP, and a larger sample size is needed.</p>

Prospective study on results of the surgical crown lengthening and its associated factors / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To observe the results of surgical crown lengthening procedure and the factors which affected the success of the surgery.</p><p><b>METHODS</b>Crown lengthening surgery was performed on 27 teeth. The distance between margin of tooth and bone crest (MT-B) was obtained greater than 4 mm during the surgeries on 10 teeth which were considered as satisfying group. The other 17 teeth were as temporized group with MT-B < or = 3 mm. The position of the tooth margin was evaluated before surgery, immediately after suturing, and at 4 - 6 weeks after surgery. The occlusal force and tooth mobility were measured immediately after restoration, at 3 and 6 months after surgery.</p><p><b>RESULTS</b>MT-B was obtained > or = 4 mm and all margins and sites of the teeth were exposed in satisfying group (10/10). At least 1 site with MT-B < 3 mm in temporized group in which there still were 11 sites (16%) in 5 teeth (29%) with subgingival tooth margin at 4 - 6 weeks after surgery. There were more teeth showing increased mobility in temporized group (12/17) than in satisfying group (1/10) after surgery (P < 0.05). The occlusal force of the teeth after surgery and restoration in temporized group was significantly lower than that of their counterpart teeth (P < 0.01), but it was not the case in satisfying group (P > 0.05).</p><p><b>CONCLUSIONS</b>It is suggested that ideal exposure of tooth margin could be obtained if 4 mm from tooth margin to alveolar crest could be created during the crown lengthening surgery. The teeth both with 4 - 5 mm subgingival margin sites and factors limiting surgical performance are not the suitable indications for the surgical crown lengthening.</p>

Two-year disease progression in mild, moderate and advanced chronic periodontitis patients / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To observe two-year natural progression of chronic periodontitis in mild, moderate and advanced periodontitis patients.</p><p><b>METHODS</b>The periodontal status of 169 untreated chronic periodontitis patients aged from 22 to 64, were examined for two years. Periodontal measurements were performed on all teeth except the third molars and 6 sites examined for each tooth. Probing depth (PD), attachment loss (AL), and bleeding on probing (BOP) were measured at baseline, one year, and two year by a same experienced periodontist. Forty-five patients were diagnosed as having mild periodontitis, 87 with moderate, and 37 with advanced periodontitis. The changes of attachment level in these three group patients were analyzed. The site with change of AL greater than 3 mm (DeltaAL > or = 3 mm) were defined as periodontal disease activity (PDA) sites. The occurrence of PDA in three groups was compared.</p><p><b>RESULTS</b>(1) The average AL levels at 1 year and at 2 year were greater than that at baseline in mild, moderate and advanced periodontitis. (2) The percentage of sites with AL > or = 1 mm in three groups all increased from baseline to 1 year and to 2 year. (3) The occurrence of periodontal disease activity increased significantly from mild (0.14% at site level, 15.56% at subject level), moderate (0.39%, 29.89%) to advanced (0.73%, 43.24%) periodontitis patients. (4) The mean baseline AL and PD levels in active sites were greater than that in inactive sites (PD: 3.03 +/- 0.45 vs. 2.87 +/- 0.38, P < 0.05; AL: 2.25 +/- 0.93 vs. 1.77 +/- 0.90, P < 0.01).</p><p><b>CONCLUSION</b>Untreated advanced periodontitis patients were the risk population for further periodontal breakdown.</p>