[Interpretation of the European Federation of Periodontology S3 level clinical practice guideline for prevention and treatment of peri-implant diseases].

The S3 level clinical practice guideline for the prevention and treatment of peri-implant diseases, developed by the European Federation of Periodontology, was published in June, 2023 (DOI: 10.1111/jcpe.13823), which culminated in the recommendations for implementation of various different interventions before, during and after implant placement/loading. Aim of the present article is to summarize and interpret the key points of this guideline and help clinicians understand this guideline better, in order to standardize the prevention and treatment of peri-implant diseases.

[Diagnosis and antidiastole of leukemia-associated gingival lesions].

Leukemia is a heterogeneous group of hematological disorders that arises from a hematopoietic stem cell characterized by a disordered differentiation and proliferation of neoplastic cells. The prevalence of leukemia is high in juveniles and adults under 35 years. Gingival manifestations of leukemia include gingiva bleeding, enlargement, pallor, petechial, ulceration, which may be the first clinical signs of leukemia. In the dental clinic, identification of leukemia-associated gingival lesions, referring patients to hematologists without delay will improve the prognosis of leukemia. Diagnosis and antidiastole of leukemia-associated gingival lesions have been discussed with reference to the related cases.

[Exploration and practice of Peking University Model to improve the clinical teaching effect of clinical postgraduates majoring in periodontology].

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.

[Healing of the dento-gingival junction following modified crown lengthening procedure in beagle dogs].

OBJECTIVE: To evaluate the type of wound healing following modified crown lengthening surgery in dog model to provide a biological basis for its clinical application. METHODS: Flap surgery, traditional crown lengthening procedure and modified crown lengthening procedure were performed on the right maxillary central incisor, the left maxillary central incisor and the left maxillary first lateral incisor respectively of five male beagle dogs. The right maxillary first lateral incisors with no surgical intervention were used as controls. Thirty-six weeks after the experimental procedure, tissue blocks were harvested and prepared for histological examination and analysis. RESULTS: Histometric examination of buccolingual sections stained with hematoxylin-eosin demonstrated that the type of wound healing in the flap surgery group was re-attachment, similar to the control group. For the traditional crown lengthening surgery group, all of the five beagle dogs had lamellar cementum defects on root surface, the wound healing of four beagle dogs was new attachment accompanied by new cementum formation at cementum defect areas and the suprac-restal connective tissue was functionally oriented perpendicular to the new cementum. The wound healing of the other beagle dog was long junctional epithelial attachment, in which the junctional epithelium extended to the apical terminus of the cementum defect. In the modified crown lengthening surgery group, four beagle dogs had cementum defects on root surface (two lamellar cementum defects and two shallow platform-like cementum defects), the wound healing of three beagle dogs was new attachment, however, the supracrestal connective tissue was parallel to the root surface. The type of wound healing of another one beagle dog was long junctional epithelial attachment. Wound healing of one beagle dog in this group could not be characterized due to incomplete dissection. CONCLUSION: Wound healing in the modified crown lengthening surgery group was similar to the traditional crown lengthening surgery group, and two types of wound healing were observed: new attachment and long junctional epithelium attachment. Neither type of root treatment procedure (root planing or root reshaping) nor root surface defect pattern (the lamellar cementum defect or shallow platform-like cementum defect) influenced the observed type of wound healing.

Monitoring mild cognitive impairment of workers exposed to occupational aluminium based on quantitative susceptibility mapping.

AIM: To investigate the diagnostic value of quantitative susceptibility mapping (QSM) in mild cognitive impairment (MCI) of aluminium (Al) workers. MATERIALS AND METHODS: The basic data of 53 workers in an Al factory were collected and divided into the MCI group and normal control (NC) group by Montreal Cognitive Assessment (MoCA) scores. All participants were tested for plasma Al concentration and had magnetic resonance imaging (MRI). The QSM values of many areas of the brain were delineated and measured. Independent two-sample t-tests or non-parametric tests were used to compare the parameter values between the two groups. Spearman's correlation analysis was performed between QSM values, MoCA scores, and plasma Al concentration. The receiver operating characteristic curve and z test were performed to assess diagnostic efficacy and the best parameter. RESULTS: There was no difference in age and educational level. Plasma Al concentration of the MCI group was higher than that of NC group (p=0.057). QSM values of the left hippocampus, left dentate nucleus, right substantia nigra, and left putamen in MCI group were higher than that of NC group (p<0.05), and the left hippocampus had the best diagnostic efficacy. QSM values correlated negatively with MoCA scores. No correlation was found between QSM values and plasma Al concentration (p>0.05). CONCLUSION: QSM might be a neuroimaging marker for the diagnosis of MCI. The left hippocampus showed the best diagnostic efficacy. Plasma Al concentration of the MCI group was higher than that of the NC group. A correlation between QSM and plasma Al concentration was not found.

[Effect of non-surgical periodontal treatment on blood inflammatory parameters, glucose and lipid metabolism in patients with periodontitis and type 2 diabetes mellitus].

Non-surgical periodontal treatment (NSPT) is the most essential part of periodontal treatment. Most patients with periodontitis and type 2 diabetes mellitus (T2DM) can achieve a satisfying outcome by NSPT. For these patients, NSPT can not only improve clinical periodontal parameters significantly and decrease the serum inflammatory status,but also improve glucose and lipid metabolism to some extent. Thus, NSPT is of great significance in preventing or retarding the progress of T2DM or even its complications. However, the special general condition of T2DM makes NSPT effects on periodontitis patients partially differ from those without systemic diseases. Therefore, the special characteristic led by T2DM should be taken into account in the decision and implementation of treatment plans for periodontitis patients. This paper will review the above issues mainly based on the studies of our research group.

[Risks and preventive strategy of periodontal treatments for patients with cardiovascular and cerebrovascular diseases].

The prevalence and mortality of the patients who suffer cardiovascular and cerebrovascular diseases are rising in China, and the number of periodontitis patients with cardiovascular and cerebrovascular diseases is growing. Certain principles should be followed during periodontal treatments for these patients due to their particular health conditions. Stomatologists should cooperate with cardiovascular physicians to evaluate the risks and benefits of periodontal treatments in advance, and to select reasonable treatment timings and plans. During treatments, the heart rates, blood pressures and other vital indicators are monitored in real time to avoid acute cardiovascular and cerebrovascular events. The application, discontinuation and adjustment of specific cardiovascular drugs are determined by cardiovascular physicians.

[Gene polymorphisms of cytochrome B-245 alpha chain (CYBA) and cholesteryl ester transfer protein (CETP) and susceptibility to generalized aggressive periodontitis].

OBJECTIVE: To explore the correlation of cytochrome B-245 alpha chain (CYBA) rs4673 and cholesteryl ester transfer protein (CETP) rs12720922 polymorphisms with the susceptibility of gene-ralized aggressive periodontitis (GAgP). METHODS: The study was a case-control trial. A total of 372 GAgP patients and 133 periodontally healthy controls were recruited. The CYBA rs4673 and CETP rs12720922 polymorphisms were detected by matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS). Logistic regression models were used to analyze the correlation of CYBA rs4673 and CETP rs12720922 variants with the susceptibility of GAgP. The interaction between the two gene polymorphisms to the susceptibility of GAgP was analyzed by the likelihood ratio test. The interaction model adopted was the multiplication model. RESULTS: The mean age of GAgP group and control group was (27.5±5.2) years and (28.8±7.1) years respectively. There was significant difference in age between the two groups (P < 0.05). The gender distribution (male/female) was 152/220 and 53/80 respectively, and there was no significant difference between GAgP group and controls (P>0.05). For CYBA rs4673, the frequency of CT/TT genotype in the GAgP group was significantly higher than that in the controls [18.0% (66/366) vs. 10.6% (14/132), P < 0.05]. After adjusting age and gender, the individuals with CT/TT genotype had a higher risk of GAgP (OR=1.86, 95%CI: 1.01-3.45, P < 0.05), compared with CC genotype. There was no statistically significant difference in distributions of the CETP rs12720922 genotypes (GG, AA/AG) between GAgP patients and healthy controls (P>0.05). A significant interaction between CYBA rs4673 and CETP rs12720922 in the susceptibility to GAgP was observed. The GAgP risk of the individuals with CYBA rs4673 CT/TT and CETP rs12720922 GG genotypes was significantly increased (OR=3.25, 95%CI: 1.36-7.75, P < 0.01), compared with those carrying CC and AA/AG genotypes. CONCLUSION: CYBA rs4673 CT/TT genotype is associated with GAgP susceptibility. There is a significant interaction between CYBA rs4673 CT/TT genotype and CETP rs12720922 GG genotype in the susceptibility of GAgP.

[Comparison of initial periodontal therapy and its correlation with white blood cell level in periodontitis patients with or without diabetes mellitus].

OBJECTIVE: To compare the clinical efficacy of initial periodontal therapy in periodontitis patients with or without type 2 diabetes mellitus and its correlation with white blood cell counts. METHODS: In this study, 32 chronic periodontitis patients without systemic disease (CP group) and 27 chronic periodontitis patients with type 2 diabetes mellitus (CP+DM group) were enrolled. At admission, all the patients went through periodontal examination and fasting blood examination(baseline). Probing depth (PD), attachment loss (AL), bleeding index (BI), plaque index (PLI), white blood cells (WBC) counts and fasting blood glucose (FBG) were recorded respectively, while hemoglobin A1c (HbA1c) was recorded only in CP+DM group. After that, initial periodontal therapy was performed. All the tests were repeated 3 and 6 months after treatment. The changes of periodontal clinical indexes and WBC levels were compared between the two groups before and after treatment, and the correlation between WBC and periodontal clinical indexes and glucose metabolism indexes were analyzed by generalized linear mixed model. RESULTS: At baseline, the periodontal inflammation and destruction were similar in CP and CP+DM group, but the WBC level was significantly higher in CP+DM groups [(6.01±1.26)×109/L vs. (7.14±1.99)×109/L, P=0.01]. After 3 and 6 months of initial periodontal therapy, the mean PD, AL, BI, and PLI in CP+DM and CP groups were significantly lower than the baseline, and the PD in CP+DM group was further decreased by 6 months compared with 3 months [(3.33±0.62) mm vs. (3.61±0.60) mm, P < 0.05]. However, none of these periodontal indexes showed significant difference between the two groups by 3 or 6 months. In CP+DM group, HbA1c at 3 months and 6 months were significantly lower than the baseline [(7.09±0.79)% vs. (7.64±1.16)%, P < 0.05; (7.06±0.78)% vs. (7.64±1.16)%, P < 0.05], and FBG was significantly lower than the baseline by 6 months [(7.35±1.14) mmol/L vs. (8.40±1.43) mmol/L, P < 0.05]. The WBC level in CP group was significantly lower than the baseline level by 3 months [(5.35±1.37)×109/L vs. (6.01±1.26)×109/L, P < 0.05], while that in CP+DM group was significantly lower than the baseline level by 6 months [(6.00±1.37)×109/L vs. (7.14±1.99)×109/L, P < 0.05]. The analysis of genera-lized linear mixed model showed that WBC level was significantly positively correlated with PD and FBG (P < 0.05). CONCLUSION: Initial periodontal therapy can effectively improve the periodontal clinical status of patients with or without type 2 diabetes mellitus, and have benefits on glycemic control in diabetic patients. However, the response of periodontal indexes and WBC level to initial therapy were relatively delayed in diabetic patients. WBC plays an important role in the correlation between diabetes mellitus and periodontitis.

[A cross-sectional study of periodontal pathogens in saliva of edentulous patients].

Objective: To investigate the prevalence of five specific periodontal pathogens in the saliva of edentulous patients and to compare the differences in the saliva of dentulous individuals with various periodontal conditions. Methods: All the subjects were patients who received regular care at the Beijing Hypertension Prevention and Management Institute. Twenty-seven edentulous patients (edentulous group) were included. According to age (age gap≤5 years), gender, smoking status, diabetes status and hypertension status, each edentulous patient was paired with dentulous individuals suffering from various severity of periodontitis in the same cohort. Then, we selected 3 groups of patients (n=27 in each group) with no or mild periodontitis (mild group), moderate periodontitis (moderate group) and severe periodontitis (severe group). The whole unstimulated saliva was collected before the periodontal examination. Questionnaire survey and periodontal parameters, including plaque index (PLI), probing depth (PD), bleeding index (BI) and clinical attachment loss (CAL), were examined at mesial-buccal and distal-lingual sites of each tooth respectively. DNA was extracted from each sample of the salivary deposition. Porphyromonas gingivalis (Pg), Tannerella forsythia (Tf), Treponema denticola (Td), Campylobacter rectus (Cr) and Prevotella nigrescens (Pn) were detected by using PCR method based on 16SrRNA. The prevalence and quantity of the pathogens under various severity of periodontitis were compared. Results: One or more periodontal pathogens could be detected from the 78% (21/27) of the salivary samples in edentulous group. Thereinto, the prevalences of the five periodontal pathogens were ranked as (from high to low): Cr [56% (15/27)], Tf [44% (12/27)], Pn [26% (7/27)], Pg [22% (6/27)] and Td [11% (3/27)]. All five pathogens' prevalences and Pg, Tf, Td and Pn's quantities showed statistical differences among the four groups. The numbers of detected bacterial species in the mild, moderate and severe groups were significantly higher than that in the edentulous group (P<0.01). Furthermore, the prevalences of the red complex in three dentulous groups [96% (26/27) in each group] were significantly higher than the edentulous group [48% (13/27)] (P<0.05). The proportions of the red complex among all five pathogens (83%) in moderate and severe groups were significantly higher than that in the edentulous group (37%) (P<0.01). Conclusions: All five periodontal pathogens could be detected in most of the saliva samples from edentulous individuals. Nevertheless, the prevalence and quantity were lower than dentulous individuals.

[Expression and distribution of calprotectin in healthy and inflamed periodontal tissues].

OBJECTIVE: Calprotectin, the heterdimer of S100A8 and S100A9, is the major cytoplasmic protein of neutrophils, which is also expressed or induced in gingival epithelial cells, activated mononuclear macrophages and vascular endothelial cells. Calprotectin is intimately associated with the initiation and progression of periodontitis, but the in vivo expression patterns of calprotectin in healthy and inflamed periodontal tissue are not fully understood. To observe the expression, distribution and cellular localization of calprotectin in the samples of healthy periodontal tissues and experimental periodontitis tissues of Beagles and to explore their relationship with periodontal inflammation and possible effect. METHODS: Experimental periodontitis model was established by ligation around the mandibular second molar of the Beagle dogs, while the contralateral teeth were healthy controls. Induction duration was 12 weeks, before the dogs were executed. Tissue specimens were demineralized and serial sections were made conventionally. The in vivo expression of calprotectin in the healthy and inflamed periodontal tissues were examined by immunohistochemistry. The in vitro expression of calprotectin in human primary gingival fibroblasts (GFs) and periodontal ligament (PDL) cells were detected by immunocytochemistry. RESULTS: Immunohistochemistry analysis indicated that calprotectin was expressed in gingival epithelial cells and infiltrated neutrophils in the healthy periodontium within the gingival epithelium, S100A8/A9 was most strongly expressed in the junctional epithelium, followed by surface epithelium, and least expressed in the sulcular epithelium. The S100A8/A9 expression levels were sharply defined at the junction between the junctional epithelium and the sulcular epithelium. In periodontal inflammatory lesions, the expression level of calprotectin in sulcular epithelium and junctional epithelium was up-regulated than that in the healthy gingival epithelium. Calprotectin was inducibly expressed in fibroblast-like cells in gingival connective tissue and periodontal ligament tissue, microvascular endothelial cells (ECs) and bone marrow fibroblasts under inflammatory conditions. Additionally, the expression of calprotectin in primary human GFs and PDL cells was confirmed by immunnocytochemistry staining. CONCLUSION: Constitutively expressed in neutrophils and gingival epithelial cells, and calprotectin might maintain the homeostasis and integrity of periodontium. Inflammation-induced expression of calprotectin in GFs, PDL cells, microvascular ECs and bone marrow fibroblasts might process anti-microbial function and promote leukocytes transmigration to defend the host against the microorganisms.

[Effects of interpregnancy interval on pregnancy outcomes of subsequent pregnancy: a multicenter retrospective study].

Objective: To explore the effects of interpregnancy interval (IPI) on pregnancy outcomes of subsequent pregnancy. Methods: A multicenter retrospective study was conducted in 21 hospitals in China. Information of age, height, pre-pregnancy weight, IPI, history of diseases, complications of pregnancy, gestational age of delivery, delivery mode, and pregnancy outcomes of the participants were collected by consulting medical records of pregnant women who had two consecutive deliveries in the same hospital during 2011 to 2018. The participants were divided into 4 groups according to IPI:<18 months, 18-23 months, 24-59 months and ≥60 months. According to the WHO's recommendation, with the IPI of 24-59 months group as a reference, to the effects of IPI on pregnancy outcomes of subsequent pregnancy were analyzed. Stratified analysis was further carried out based on age, history of gestational diabetes mellitus (GDM), macrosomia, and premature delivery, to explore the differences in the effects of IPI on pregnancy outcomes among women with different characteristics. Results: A total of 8 026 women were included in this study. There were 423, 623, 5 512 and 1 468 participants in <18 months group, 18-23 months group, 24-59 months group and ≥60 months group, respectively. (1) The age, pre-pregnancy body mass index (BMI), history of cesarean section, GDM, gestational hypertension and cesarean section delivery rate of <18 months group, 18-23 months group, 24-59 months group and ≥60 months group were gradually increased, and the differences were statistically significant (P<0.05). (2) After adjusting for potential confounding factors, compared with women in the IPI of 24-59 months group, the risk of premature delivery, premature rupture of membranes, and oligohydramnios were increased by 42% (OR=1.42, 95%CI: 1.07-1.88, P=0.015), 46% (OR=1.46, 95%CI: 1.13-1.88, P=0.004), and 64% (OR=1.64, 95%CI: 1.13-2.38, P=0.009) respectively for women in the IPI≥60 months group. No effects of IPI on other pregnancy outcomes were found in this study (P>0.05). (3) After stratified by age and adjusted for confounding factors, compared with women in the IPI of 24-59 months group, IPI≥60 months would significantly increase the risk of oligohydramnios for women with advanced age (OR=2.87, 95%CI: 1.41-5.83, P=0.004); and <18 months could increase the risk of premature rupture of membranes for women under the age of 35 (OR=1.59, 95%CI: 1.04-2.43, P=0.032). Both the risk of premature rupture of membranes (OR=1.58, 95%CI: 1.18-2.13, P=0.002) and premature delivery (OR=1.52, 95%CI: 1.07-2.17, P=0.020) were significantly increased in the IPI≥60 months group. After stratified by history of GDM and adjusted for confounding factors, compared with women in the IPI of 24-59 months group, IPI≥60 months would lead to an increased risk of postpartum hemorrhage for women with a history of GDM (OR=5.34, 95%CI: 1.45-19.70, P=0.012) and an increased risk of premature rupture of membranes for women without a history of GDM (OR=1.44, 95%CI: 1.10-1.90, P=0.009). After stratified by history of macrosomia and adjusted for confounding factors, compared with women in the IPI of 24-59 months group, IPI≥60 months could increase the proportion of cesarean section for women with a history of macrosomia (OR=4.11, 95%CI: 1.18-14.27, P=0.026) and the risk of premature rupture of membranes for women without a history of macrosomia (OR=1.46, 95%CI: 1.12-1.89, P=0.005). After stratified by history of premature delivery and adjusted for confounding factors, compared with women in the IPI of 24-59 months group, IPI≥60 months would significantly increase the risk of premature rupture of membranes for women without a history of premature delivery (OR=1.47, 95%CI: 1.13-1.92, P=0.004). Conclusions: Both IPI≥60 months and <18 months would increase the risk of adverse pregnancy outcomes in the subsequent pregnancy. Healthcare education and consultation should be conducted for women of reproductive age to maintain an appropriate IPI when they plan to pregnant again, to reduce the risk of adverse pregnancy outcomes in the subsequent pregnancy.

[S100A8/A9 and periodontal inflammatory diseases].

Calprotectin S100A8/A9, a heterodimer composed of S100A8 and S100A9, is the main component of cytoplasmic proteins in neutrophils. It plays multiple roles in the immuno-inflammatory reactions intracellularly and extracellularly. Recent studies find that S100A8/A9 is closely related with the initiation and progression of periodontal inflammatory diseases. S100A8/A9 is expected to be a new biomarker for diagnosing periodontal inflammatory diseases, monitoring inflammatory activities in patients with periodontitis, evaluating the outcome of periodontal treatments and predicting the susceptibility of individual patient to periodontitis. In this literature review, we summarize the clinical research progress on the relation between S100A8/A9 and periodontal inflammatory diseases.

[Effect of initial periodontal therapy on blood parameters related to erythrocyte and platelet in patients with type 2 diabetes mellitus and chronic periodontitis].

OBJECTIVE: To compare the blood parameters related to erythrocyte and platelet between baseline and 3 months after initial periodontal therapy in patients with both type 2 diabetes mellitus and chronic periodontitis (DM-P). METHODS: According to the International Symposium on Classification of Periodontal Diseases and Conditions in 1999 and the diagnostic criteria of type 2 diabetes mellitus proposed by the World Health Organization in 1999, 35 patients with DM-P were recruited. All the participants received initial periodontal therapy, including oral hygiene instruction, scaling, and root planning provided by one senior periodontist. Original diet, exercise, and medication for blood glucose control were unchanged for all the participants. At baseline and 3 months after initial periodontal therapy, the clinical periodontal parameters, including probing depth (PD), bleeding index (BI) and clinical attachment loss (CAL); erythrocyte-related indexes, including red blood cell (RBC) count, hemoglobin (HGB), hematocrit (HCT), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), RBC volume distribution width (RDW); platelet-related indexes, including platelet (PLT) count, mean platelet volume (MPV), platelet distribution width (PDW), plateletocrit (PCT) were measured and compared. RESULTS: Compared with baseline, the periodontal parameters, including PD [(3.370±0.601) mm vs. (2.729±0.431) mm], BI [2.160 (1.550~3.410) vs. 1.420 (1.000~2.970)] and CAL [(3.307±1.577) mm vs. (2.990±1.587) mm], were significantly reduced (P < 0.001) three months after the initial periodontal therapy; the erythrocyte-related indexes, including RBC count [(4.727±0.392)×1012/L vs. (4.825±0.394)×1012/L, P=0.010], HGB [(145.886±11.792) g/L vs. (149.200±12.979) g/L, P=0.007] and HCT [43.40% (37.50%~48.50%) vs. 43.80% (38.50%~53.20%), P=0.003], were significantly increased three months after the initial periodontal therapy; PLT count [(216.714±61.900)×109/L vs. (205.886±62.051)×109/L, P=0.016] was significantly reduced 3 months after the initial periodontal therapy. CONCLUSIONS: The initial periodontal therapy can significantly improve blood parameters related to RBC and PLT, which might decrease the risk of vascular complications in DM-P patients.

[Effect of systemic use of amoxicillin and metronidazole during mechanical therapy on the periodontal microorganisms in subgingival plaque and saliva of patients with aggressive periodontitis].

Objective: To explore the effect of systemic use of amoxicillin and metronidazole during mechanical therapy on the clinical parameters of the first molars and periodontal microorganisms in subgingival plaque and saliva in patients with generalized aggressive periodontitis (GAgP). Methods: A total of 23 GAgP patients were recruited from Peking University School and Hospital of Stomatology from January 2006 to December 2009 and then randomly divided into two groups according to random number table: 12 patients received scaling and root planning (SRP) only and 11 patients received SRP combined with systemic administration of antibiotics (amoxicillin and metronidazole for a week after supragingival scaling). Clinical examination of periodontal parameters and collection of saliva and pooled subgingival plaque samples from mesial-buccal sites of 4 first molars were performed before initial therapy and 2, 4 and 6 months respectively after mechanical therapy, and saliva samples were also collected 2 weeks after therapy. Eight different periodontal microorganisms were detected in these samples by PCR. In addition, semiquantitative analysis of red complex microorganisms [Porphyromonas gingivalis (Pg), Tannerella forsythia (Tf), Treponema denticola (Td)] was performed. Results: Both therapies led to significant decrease of the plaque index (PLI), probing depth (PD) and bleeding index (BI) from mesial-buccal sites of first molars. Meanwhile the PD of antibiotics group [(4.21±1.50), (4.00±1.54), (3.84±1.89) mm of 2, 4 and 6 months respectively after therapy] was significantly lower than the SRP group [(5.29±1.27), (5.30±1.34), (4.98±1.36) mm of 2, 4 and 6 months respectively after therapy] at 3 different time points after mechanical therapy (P<0.05). In the antibiotics group, the quantities of Pg, Tf and Td in subgingival plaque samples (the median quantity decreased to 0.0 ng at 2, 4 and 6 months after therapy) and saliva samples (the median quantity of Tf and Td decreased to 0.0 ng at 2, 4 and 6 months after therapy (P<0.05), and the median quantity of Pg decreased to 16.3, 59.6 and 22.4 ng at 2, 4 and 6 months respectively after therapy) significantly decreased at 3 different time points after mechanical therapy compared with before therapy (P<0.05). While in the SRP group, there were no significant changes in the quantities of Tf and Td in saliva at 2, 4 and 6 months after mechanical therapy (P>0.05) , and the quantities of Tf and Td in subgingival plaque significantly decreased only at 2 months after therapy (P<0.05). Conclusions: SRP combined with systemic administration of amoxicillin and metronidazole could achieve greater improvement in PD of first molars and better control of the amounts of red complex microorganisms in the saliva and subgingival plaque of GAgP patients over a 6-month period.

[Interaction analysis between epidermal growth factor and peroxidase proliferators activate receptor-α gene polymorphism and susceptibility to generalized aggressive periodontitis].

Objective: To explore the correlation and interaction between epidermal growth factor (EGF) rs2237051 and peroxidase proliferators activate receptor-α (PPAR-α) rs4253623 polymorphisms and the susceptibility of generalized aggressive periodontitis (GAgP). Methods: Two hundred and nineteen Chinese patients with GAgP were enrolled from the patients of the Department of Periodontology, Peking University School and Hospital of Stomatology from January 2001 to December 2015. The control group comprised 138 periodontally healthy volunteers recruited from the staff and students of the Peking University School and Hospital of Stomatology. The EGF rs2237051 and PPAR-α rs4253623 polymorphisms were genotyped using time-of-flight mass spectrometry. Logistic regression models were conducted to analyze the correlation between the EGF rs2237051 and PPAR-α rs4253623 variants with GAgP. The likelihood ratio test was used to analyze whether there was an interaction between the two polymorphisms in the susceptibility of GAgP. The interaction model adopted was the multiplication model. Results: The mean ages of GAgP group (male:87; female:132) and control group (male: 53; female: 85) were (27.3±4.5) years and (27.1±4.2) years respectively and there was no significant difference in age and gender distribution between the two groups. For EGF rs2237051, the frequency of AA genotype in the GAgP group [49.5% (107/216)] was significantly higher than that in the control group [37.7% (52/138)], and the frequency of AG/GG genotype in the GAgP group [50.5% (109/216)] was significantly lower than that in the control group [62.3% (86/138)](P<0.05). Compared with AA genotype, individuals with AG/GG genotype had a 39% lower risk of GAgP after adjustment of age and gender (OR: 0.61, 95%CI: 0.40-0.95, P<0.05). For PPAR-α rs4253623, the frequency of AA genotype in the GAgP group [76.2% (160/210)] was significantly higher than that in the control group [65.9%(81/123)], and the frequency of AG/GG genotype in the GAgP group [23.8% (50/210)] was significantly lower than that in the control group [34.1%(42/123)] (P<0.05). Compared with AA genotype, individuals with AG/GG genotype had a 40% lower risk of GAgP after adjustment of age and gender (OR: 0.60, 95%CI: 0.36-0.98, P<0.05). EGF rs2237051 and PPAR-α rs4253623 showed a significant interaction in the susceptibility to GAgP. Compared with AA genotype, the risk of GAgP in individuals with both AG/GG genotypes of EGF rs2237051 and PPAR-α rs4253623 was reduced by 66% (OR: 0.34, 95%CI: 0.17-0.66, P<0.01). Conclusions: EGF rs2237051 and PPAR-α rs4253623 are correlated with GAgP susceptibility, and there is a significant interaction between them in the susceptibility of GAgP. The G allele of the two loci has a protective effect on the disease of GAgP.

[Preliminary study on the expression and distribution of S100A8 and S100A9 in healthy and experimental periodontitis tissues].

Objective: To investigate the systemic expression profile of S100A8 and S100A9 in healthy and inflamed periodontal tissues. Methods: Experimental periodontitis models were established by ligations around the mandibular second molars of six beagle dogs for 12 weeks (ligation group). The mandibular second molars on the opposite side were kept clean (healthy control group). The expressions of S100A8 and S100A9 in healthy and inflamed periodontal tissues of six beagle dogs were examined by immunohistochemistry. The expressions of S100A8 and S100A9 in primary human gingival fibroblasts (hGF) from 3 subjects and human periodontal ligament cells (hPDLC) from 3 other subjects were detected by immunocytochemistry. Results: After the ligation for 12 weeks, the mean probing depth of ligation group [(3.86±0.14) mm] was significantly higher than that of healthy control group [(2.11±0.28) mm] (P<0.01). Results of immunohistochemistry analysis indicated that S100A8 and S100A9 could be expressed in gingival epithelial cells and might infiltrated neutrophils in the healthy periodontium. Except for the gingival epithelial cells and neutrophils, both proteins were induced and expressed in gingival fibroblasts, periodontal ligament cells, microvascular endothelial cells and bone marrow fibroblasts under inflammatory conditions. The distribution of S100A8 and S100A9 differed in the healthy oral gingival epithelium (OGE), which becomes consistent in inflamed OGE. Additionally, the expressions of S100A8 and S100A9 were confirmed in primary hGF and hPDLC. Conclusions: Periodontal inflammation might enlarge the expression scope of S100A8 and S100A9 and enrich multiple cells with expressions of S100A8 and S100A9.

[Effect of vertical soft tissue thickness on clinical manifestation of peri-implant tissue in patients with periodontitis].

OBJECTIVE: To observe and investigate the effect of vertical soft tissue thickness on the peri-implant tissue condition and the prevalence of peri-implant disease in patients with history of periodontitis. METHODS: Among 210 patients who showed initial interest of implant therapy, 92 patients were included in this study and received implant surgery during 2010 and 2015. Sixty-six patients with 66 implants finally came back for T2 evaluation. Prior to the implant therapy, all the patients had received periodontal treatment. During the implant placement surgery, the distance from palatal soft tissue edge to the alveolar crest, which was defined as vertical soft tissue thickness (VT), was measured after the buccal full thickness flap was elevated. According to the cut off point which was adopted from the operating characteristic curve, 66 implants within 66 patients were divided into two groups, which were called normal group (VT≤4.5 mm) and thick group (VT>4.5 mm), respectively. Information of the patient's general status, periodontal situation and implant information were recorded. After a follow-up period of 42.9 months, the parameters of peri-implant tissue and condition of peri-implant disease were recorded. Mann-Whitney U test as well as Chi-square test were used to compare the parameters between two groups. Moreover, Kaplan-Meier method was chosen to draw the event(peri-implantitis)-free survival curve. RESULTS: The survival rate of the implants was 100%. At the end of the follow-up examination(T2), the parameters including max PDi, mean PDi, max BIi, mean BIi, mean MBL, MBL at distal side, MBL at mesial side, mean PLIi presented significantly higher values in thick group than in normal group (P < 0.05). Moreover, the prevalence of peri-implantitis and peri-implant disease (peri-implant mucositis & peri-implantitis) in thick group was respectively 34.8% and 73.9%, which was significantly higher than 2.3% and 48.8% respectively in normal group (P<0.05). The prevalence of peri-implant mucositis did not show significant difference in the two groups. In addition, Kaplan-Meier analysis showed that there was significant difference between the event-free survivals of the two groups. CONCLUSION: The vertical soft tissue thickness around implants in patients with periodontitis has a significant effect on the health of the peri-implant tissue. Excessive vertical soft tissue thickness may result in deeper peri-implant probing depth as well as more peri-implant marginal bone loss, and eventually increase the risk of peri-implant disease. The vertical remodeling of soft tissue may be a new direction to indicate the role of periodontitis in peri-implant tissue condition. Moreover, the biological mechanism of the association between soft tissue thickness and peri-implantitis risk as well as effective approaches to prevent the adverse effect of excessive soft tissue thickness on peri-implant tissue is necessary to be investigated.

[Short-term outcome of regenerative surgery treating peri-implantitis].

OBJECTIVE: To evaluate the short-term outcome of regenerative surgery for peri-implantitis therapy. METHODS: From March 2018 to January 2019, 9 patients with 10 implants who suffered from peri-implantitis were included in the present research. Vertical bone defect at least 3mm in depth with 2 or more residual bone walls was confirmed around each implant by radiographic examination. Restorations were replaced by healing abutments on 3 implants with the consent of the patients. Guided bone regeneration surgery was performed after a hygienic phase. During surgery, full thickness flaps were elevated on both buccal and lingual aspects. Titanium curette was used for inflammatory granulation tissue removal and implant surface cleaning. The implant surface was decontaminated by chemical rinsing with 3% hydrogen peroxide solution. After being thoroughly rinsed with saline, the bone substitutes were placed in bone defects which were covered by collagen membranes. 6 months after non-submerged healing, the clinical parameters including peri-implant probing depth (PD, distance between pocket bottom and peri-implant soft tissue margin) and radiographic bone level (BL, distance form implant shoulder to the first bone-to-implant contact) were used to evaluate the regenerative outcome. PD was measured at six sites (mesial, middle and distal sites at both buccal and lingual aspects) around each implant, and BL was measured at the mesial and distal surfaces of each implant on a periapical radiograph. RESULTS: The deepest PD and largest BL of each implant ranged from 6-10 mm and 3.2-8.3 mm respectively. All the implants healed uneventfully after surgery. The mean peri-implant PD at baseline and 6 months after surgery were (6.2±1.4) mm and (3.1±0.6) mm respectively, and a mean (3.0±1.5) mm radiographic bone gain was observed, P<0.01. Treatment success was defined as: no sites with residual PD≥6 mm, no bleeding on probing, and BL elevation of at least 1 mm. Nine implants from 8 patients fulfilled the success criteria. Residual pockets with 6 mm in depth and bleeding on probing could be detected in only one implant. CONCLUSION: Within the limitation of the present research, guided bone regeneration surgery can be used for the treatment of bone defect that resulted from peri-implantitis. Significant PD reduction and radiographic bone gain can be obtained after 6 months observation.

[Influential factors related to the long-term effect of periodontal-orthodontic treatment in patients with aggressive periodontitis and malocclusion].

Objective: To investigate the influential factors related to the long-term effect of periodontal-orthodontic treatment in patients with aggressive periodontitis (AgP). Methods: A retrospective analysis was conducted in 25 AgP patients, who have received periodontal-orthodontic treatment in Peking University School and Hospital of Stomatology. Changes in the ratio of the residual alveolar bone height (RBH) was measured at three time points: baseline (T0), post orthodontic treatment (T1), and the last re-visit 3 years after orthodontic treatment (T2). Root abnormity was evaluated by observing periapical radiographs, and its relationship with alveolar bone loss after orthodontic treatment was analyzed. A multi-level analysis on factors related to the clinical outcome (alveolar bone height change) was performed. Results: Totally 693 teeth of 25 patients at T0 and T1 and 368 teeth of 14 patients at T2 were investigated. During the periodontal-orthodontic treatment, the RBH was mainly influenced by root abnormity (estimation value -2.392), tooth position (estimation value for upper teeth vs. lower teeth 3.139, and anterior teeth vs. posterior teeth -3.469) and the baseline RBH at T0 (estimation value -0.391) (P<0.05). Teeth with root abnormity, teeth in mandibular and anterior area, and teeth with higher RBH showed less change in T1-T0 RBH values. In the long-term follow-up, RBH was mainly influenced by tooth position (estimation value for upper teeth vs. lower teeth 3.735, and anterior teeth vs. posterior teeth -5.318), the baseline RBH and probing depth (PD) at T0. Teeth in mandibular and anterior area, teeth with higher RBH (estimation value -0.498) and PD (estimation value -1.594) (P<0.05) showed less change in T0-T2 RBH values. Conclusions: During orthodontic treatment, teeth with abnormal root, lower teeth, anterior teeth, and teeth with high RBH were unfavorable factors for bone gain. In the long-term observation, lower teeth, anterior teeth, teeth with high RBH and PD at first visit were unfavorable factors for bone gain.