To evaluate the relationship between-590C/T polymorphisms of interleukin-4 gene and periodontitis by meta-analysis.

Databases including PubMed, EMbase, Web of Science, CBM, CNKI, Wanfang and VIP, were searched from their establishment to December 31, 2016. Only case-control studies on the association between-590C/T polymorphisms of interleukin-4 gene and periodontitis were selected, and the references of those selected studies were searched by hand. Assessment and data extraction were conducted by 2 reviewers independently, and the meta-analysis was performed with the R 3.3.1 software.

The meta-analysis showed that there was no association between the IL-4-590C/T polymorphism and periodontitis susceptibility (T vs C: OR＝1.19, 95%CI＝0.81~1.76, P ＝0.37). Subgroup analysis showed that the IL-4-590 TT was associated with periodontitis in Caucasians (TT vs CT: OR＝1.75, 95%CI＝1.10 ~ 2.78, P ＝ 0.02), but no significant association in Asians (P ＝0.63). Meanwhile, IL-4 gene polymorphisms were not significantly associated with the susceptibility of chronic periodontitis (CP) or aggressive periodontitis (Ag P) (e. g. T vs C, CP: P＝0.45; Ag P: P ＝0.45).

Based on current evidence, the polymorphisms of IL-4-590C/T are associated with the increased risk of periodontitis in Caucasians.

To analyze the tooth movement distance and root resorption in rats under different orthodontic forces, to explore the effect of orthodontic force on the root resorption during orthodontic tooth movement.

64 male Sprague Dawley (SD) rats aged 10 months weighting 220-270 g in this study. 10 g and 30 g nickel-titanium closed-coil springs were applied mesially to the maxillary right first molars, while contralateral first molar was severed as a control. At day 3, 7, 14 and 28 after loading, the molars were extracted. The tooth movement distance and the volume on the surface area of root resorption were measured and scaned by Micro-CT.

Tooth movement gradually increased after loading. For 10 g group, 30 g group showed farther tooth movement distance with time throughout 14 days (P = 0.039), but there was a reverse result at day 28 (P＜0.05). There was a significant increased in the root resorption craters between the control group and the 10 g/ 30 g group after 28 days of loading (P = 0.004), and the deeply root resorption were observed on the 30 g group (P＜0.001).

Reliable evaluation and quantitative analysis in the tooth movement and the root resorption could be done by Micro-CT. Tooth movement in the 10 g group was more rapid than the 30 g group, nevertheless, the root resorption craters was less reduced after 28 days loading.