[Extraction treatment on orthodontic patients with Stage â £/Grade C periodontitis: a preliminary study].

Objective: To evaluate the effect of extraction treatment on orthodontic patients with Stage Ⅳ/Grade C periodontitis. Methods: Eight orthodontic patients with Stage Ⅳ/Grade C periodontitis (3 males, 5 females, 25~38 years old) who had finished extraction treatment during January 2003 and December 2013 were included in the study. The patients accepted periodontal treatment and extraction orthodontic treatment in the Department of Periodontology and Department of Orthodontics at Peking University School and Hospital of Stomatology. Clinical examination records and periapical films of 34 teeth adjacent to extraction sites (TAES) and 34 teeth non-adjacent to extraction sites (TNES) were evaluated and compared. Probing depth (PD) and relative bone height (RBH) before and after orthodontic treatment were also compared. Results: No significant difference was found between PD of TAES and that of TNES (P>0.05). After orthodontic treatment, RBH of TAES was increased by 8.19% (-3.36%,14.01%) (P<0.05). RBH of TAES far from extraction sites was elevated by 7.73% (-1.52%, 21.55%)(P<0.05). Tooth resorption rate of TAES was 13.1% (1.3%, 23.9%)and TNES was 4.3% (-8.19%, 12.5%) after orthodontic treatment, and the difference was statistically significant. Conclusions: Under proper combined periodontal and orthodontic treatment, stability of periodontal status in patients with Stage Ⅳ/Grade C periodontitis can be maintained. Relative bone height of extraction sites can be elevated after orthodontic treatment.

Versatile mechanical properties of novel g-SiC x monolayers from graphene to silicene: a first-principles study.

Recently, a series of graphene-like binary monolayers (g-SiC x ), where Si partly substitutes the C positions in graphene, have been obtained by tailoring the band gaps of graphene and silicene that have made them a promising material for application in opto-electronic devices. Subsequently, evaluating the mechanical properties of g-SiC x has assumed great importance for engineering applications. In this study, we quantified the in-plane mechanical properties of g-SiC x (x = 7, 5, 3, 2 and 1) monolayers (also including graphene and silicene) based on density function theory. It was found that the mechanical parameters of g-SiC x , such as the ideal strength, Young's modulus, shear modulus, Poisson's ratio, as well as fracture toughness, are overall related to the ratio of Si-C to C-C bonds, which varies with Si concentration. However, for g-SiC7 and g-SiC3, the mechanical properties seem to depend on the structure because in g-SiC7, the C-C bond strength is severely weakened by abnormal stretching, and in g-SiC3, conjugation structure is formed. The microscopic failure of g-SiC x exhibits diverse styles depending on the more complex structural deformation modes introduced by Si substitution. We elaborated the structure-properties relationship of g-SiC x during the failure process, and in particular, found that the structural transformation of g-SiC3 and g-SiC is due to the singular symmetry of their structure. Due to the homogeneous phase, all the g-SiC x investigated in this study preserve rigorous isotropic Young's moduli and Poisson's ratios. With versatile mechanical performances, the family of g-SiC x may facilitate the design of advanced two-dimensional materials to meet the needs for practical mechanical engineering applications. The results offer a fundamental understanding of the mechanical behaviors of g-SiC x monolayers.

[Extraction-orthodontic treatment on patients with chronicperiodontitis: a preliminary study].

OBJECTIVE: To retrospectively evaluate clinical and radiographic records of chronic periodontitis patients who underwent extraction-orthodontic treatment, in order to determine the effect of the treatment on probing depth, alveolar bone height of teeth adjacent to the extraction sites. METHODS: In the study, 33 chronic periodontitis patients who had finished extraction-orthodontic treatment were selected, the periodontal examination system tables and panoramic tomography were recorded before treatment (T0) and after treatment (T1), and the periodontal probing depth (PD), residual alveolar bone height (RBH) of the teeth adjacent to extraction sites (TAES) and the non-teeth adjacent to extraction sites (NTAES) were measured at T0 and T1. RESULTS: There was insignificant difference in PD of TAES and NTAES at T0 [(2.40±0.51) mm vs. (2.42±0.55) mm,P>0.05], neither was that at T1 [(2.70±0.67) mm vs. (2.67±0.64) mm, P>0.05]; From T0 to T1, PD of TAES and NTAES had mean increases of 0.3 mm [(2.40±0.51) mm vs. (2.70±0.67) mm,P<0.01] and 0.25 mm [(2.42±0.55 mm vs. (2.67±0.64) mm, P<0.01], respectively. And PD of TAES and NTAES increased from T0 to T1 statistically in the same degree [(0.30±0.64) mm vs. (0.25±0.58) mm,P>0.05]; at T0, RBH of TAES was 0.024 smaller than that of NTAES (0.74±0.16 vs. 0.76±0.16,P<0.05), but there was no difference in RBH between the TAES and NTAES at T1 (0.78±0.14 vs. 0.79±0.12,P>0.05); From T0 to T1, RBH of TAES and NTAES had mean increases of 0.04 (0.74±0.16 vs.0.78±0.14,P<0.05) and 0.02 (0.76±0.16 vs. 0.79±0.12,P<0.05), respectively. And the change of RBH between TAES and NTAES from T0 to T1 had no statistical difference (0.04±0.11 vs. 0.02±0.08,P>0.05)RBH of TAES in the side close to extraction sites was as the same as that of TAES in the side away from the extraction sites at T0 (0.73±0.17 vs. 0.74±0.16,P>0.05). From T0 to T1, RBH of both sides of TAES had mean increases of 0.04 (0.73±0.11 vs. 0.77±0.11,P<0.05) and 0.04 (0.74±0.11 vs. 0.78±0.11,P<0.05), respectively. But for both sides of TAES, from T0 to T1, there was no significant difference in change of RBH (0.04±0.11 vs. 0.04±0.11,P>0.05). CONCLUSIONS: With strict control of periodontal inflammation and maintenance of oral hygiene, orthodontic treatment preserves the periodontal conditions in patients with chronic periodontitis, and the extraction-orthodontic treatment can preserve the bone height of the teeth adjacent to extraction sites.

Pharmacokinetics of four 5-FU preparations administered rectally to rats and rabbits.

AIM: To compare the pharmacokinetic characteristics of four preparations of fluorouracil (5-FU) administered rectally using a rat model. METHODS: Concentrations of 5-FU were measured in plasma, the rectal wall and mesentery lymph tissues of rats and rabbits by high performance liquid chromatography. Differences between the main pharmacokinetic parameters were compared by statistical analysis. RESULTS: The 5-FU concentrations in the rectal wall and mesenteric lymph tissues were significantly higher than the concentration in blood following rectal administration for all four of the preparations (P < 0.01). The drug level in the rectal wall was higher in the animals received delivery of an emulsion, compared to those who received delivery as a suppository (P < 0.05). Moreover, the animals who received a lipophil-based suppository had lower plasma level of drug than those who received a hydrophil-based suppository, and the animals who received the simple (o/w) emulsion had lower plasma level than those who received the complex (w/o/w) emulsion. The differences found in the rat model were confirmed in rabbits (P < 0.01). CONCLUSION: The lipophil-based suppository and the simple emulsion of 5-FU might be more suitable for rectal administration for treatment of rectal cancers.