Effect of Periodontal Treatment on the Crevicular Level of High-mobility Group Box 1 and Soluble Triggering Receptor Expressed on Myeloid Cells 1 in Patients with Chronic Periodontitis.

The present study aimed to compare the levels of high-mobility group box 1(HMGB1) and soluble triggering receptor expressed on myeloid cells (sTREM1) in the gingival crevicular fluid (GCF). This cross-sectional cohort trial investigated two groups of 22 eligible chronic periodontitis and 22 periodontally healthy individuals (student volunteers) both before and after the periodontal treatment.  GCF was collected from the deepest pockets with clinical attachment loss≥3 mm. Both groups received oral hygiene instructions, and scaling and root planning were performed in the test group. Enzyme-linked immunosorbent assay kit (ELISA) was used to measure the levels of HMGB1 and sTREM1 in GCF samples collected before and 1 month after non-surgical periodontal treatment. The results showed that HMGB1 levels were significantly higher in the chronic periodontitis patients than those of the healthy individuals before treatment (p<0.02) and decreased significantly after periodontal treatment, which reduced gingival inflammation. Furthermore, the levels of sTREM1 marker were significantly higher in periodontitis patients before (p<0.001) and 1 month after treatment than in healthy individuals (p<0.003) although its crevicular levels decreased after periodontal therapy in periodontitis group. The higher levels of sTREM1 and HMGB1 cytokines in GCF of periodontitis patients and the significant decrease after the introduction of the periodontal treatment underlines the importance of HMGB1 and sTREM1 in pathogenesis of periodontitis.

Relationships between High-mobility Group Protein B1 and Triggering Receptor Expressed on Myeloid Cells Concentrations in Gingival Crevicular Fluid and Chronic Periodontitis.

One of the inflammatory mediators which is secreted by inflammatory cells is high-mobility group protein B1 (HMGB1). Interaction of HMGB1 and toll-like receptors (TLRs) leads to increased production of inflammatory cytokines. On the other hand, it was shown that triggering receptor expressed on myeloid cells (TREM-1) also can be activated by TLRs, and its soluble form (sTREM-1) can be formed by cleaving of membrane-bound form of TREM-1 proteinases. Since there is not enough knowledge about the precise role of HMGB1 and sTREM-1 in periodontal diseases, the aim of this study was to evaluate the concentration of HMGB1 and sTREM-1 in gingival crevicular fluid (GCF) samples of patients with chronic periodontitis. Gingival crevicular fluid (GCF) samples were obtained from a total of 24 individuals with clinically healthy gingiva and 24 patients with moderate to severe chronic periodontitis. For collecting GCF samples, periopapers were placed at the entrance of the crevice and left in position for 30 seconds. Then, they were stored at -80°C. Enzyme-linked immunosorbent assay (ELISA) was used for measuring the concentration of HMGB1 and sTREM-1 in GCF samples. The concentration of HMGB1 (p<0.001) and sTREM-1 (p<0.017), was significantly higher in chronic periodontitis group. In addition, there was a significant positive correlation between HMGB1 and sTREM-1 concentration in chronic periodontitis group (p<0.05). We also found significant positive correlation between PD (Pocket depth) and the concentration of HMGB1 (p<0.001) and sTREM-1 (p<0.015). It is concluded that both HMGB1 and sTREM-1 are released during the inflammatory response of periodontal tissues and they can promote inflammatory process, which leads to tissue destruction.

Histologic evaluation of bone healing capacity following application of inorganic bovine bone and a new allograft material in rabbit calvaria.

OBJECTIVES: Considering the importance of bone augmentation prior to implant placement in order to obtain adequate bone quality and quantity, many studies have been conducted to evaluate different techniques and materials regarding new bone formation. In this study, we investigated the bone healing capacity of two different materials deproteinized bovine bone mineral (DBBM with the trade name of Bio-Oss) and demineralized freeze-dried bone allograft (DFDBA with the trade name of DynaGraft). MATERIALS AND METHODS: This randomized blinded prospective study was conducted on twelve New Zealand white rabbits. Three cranial defects with an equal diameter were created on their calvarium. Subsequently, they were distributed into three groups: 1. The control group without any treatment; 2. The Bio-Oss group; 3. The DynaGraft group. After 30 days, the animals were sacrificed for histologic and histomorphometric analysis. RESULTS: Substantial new bone formation was observed in both groups. DynaGraft: 56/1 % ± 15/1 and Bio-Oss: 53/55 % ± 13/5 compared to the control group: 28/6 % ± 11/2. All groups showed slight inflammation and a small amount of residual biomaterial was observed. CONCLUSION: Considerable new bone formation was demonstrated in both DynaGraft and Bio-Oss groups in comparison with the control group. Both materials are considered biocompatible regarding the negligible foreign body reaction.

Cementogenesis in Patients with Localized Aggressive Periodontitis.

OBJECTIVES: The aim of this study was to determine the cementum thickness in the first molars of patients with localized aggressive periodontitis (LAP) compared to healthy individuals. MATERIALS AND METHODS: This case-control study compared eight first molar teeth affected by LAP with eight third molar teeth of healthy individuals. The teeth were disinfected by immersion in 10% buffered formalin solution for three days and were then sectioned. External mesial root surfaces (middle one-third) were evaluated under a stereomicroscope by a blinded pathologist to determine the mean thickness of cementum. SPSS software (version 16.0) and t-test were used for statistical analysis. RESULTS: Histological examination revealed a significant difference between the two groups in terms of the amount of cementogenesis (P<0.001) .The thickness of cementum was higher in the control group (105.16±11.5 µm) than in LAP patients (86.44±7.3 µm). CONCLUSION: This study demonstrated the presence of cementum hypoplasia in mesial root surfaces of first molars affected by LAP.

Effects of two types of anorganic bovine bone on bone regeneration: a histological and histomorphometric study of rabbit calvaria.

OBJECTIVE: The purpose of this study was to evaluate the efficacy of two types of bone substitutes, Bio-Oss and NuOss, for repair of bone defects. MATERIALS AND METHODS: This study was performed on the calvaria of 14 New Zealand rabbits. The 6mm critical size defect (CSD) models of bone regeneration were used. Three CSDs were created in each surgical site. The first defect was filled with NuOss, the second one with Bio-Oss and the third one remained unfilled as the control. After healing periods of one and two months (seven animal for each time point), histological and histomorphometric analyses were carried out to assess the amount of new bone formation, presence of inflammation, foreign body reaction and type of new bone. Qualitative variables were analyzed by multiple comparisons, Wilcoxon, Friedman and Mann Whitney tests. Quantitative variables were analyzed using the Mann-Whitney and Wilcoxon tests. Level of statistical significance was set at 0.05. RESULTS: The level of inflammation was not significantly different at four and eight weeks in the Bio-Oss (P=0.944), NuOss (P=1.000) and control groups (P=0.71). At four weeks, foreign body reaction was not observed in Bio-Oss, NuOss and control groups. There was no significant difference in the type of the newly formed bone at four and eight weeks in any group (P=0.141 for Bio-Oss, P=0.06 for NuOss and P=0.389 for the control group). CONCLUSION: Deproteinized bovine bone mineral can be used as a scaffold in bone defects to induce bone regeneration.