The effect of provincial policies on seismic disaster mitigation in China: An empirical study.

With the development of earthquake disaster reduction efforts in China, the content of earthquake disaster reduction policies has become increasingly enriched and improved. Particularly, multiple provincial governments have proposed earthquake disaster reduction planning policies. It is important to explore whether these policies can affect disaster mitigation. Therefore, this paper summarizes the earthquake disaster reduction plans and factors influencing seismic resilience. Panel data from 24 provinces between 2012 and 2021 were collected, and a difference-in-differences approach was used to construct an econometric model to evaluate the policy effects and analyze the enhancement of seismic resilience. The results show that the implementation of earthquake disaster reduction policies has a positive impact on earthquake monitoring, evacuation, and emergency relief capabilities, and the estimated policy effects are statistically significant. Moreover, a series of tests were conducted. The conclusions are as follows: (1) Earthquake disaster reduction policies have a positive impact on the improvement of seismic resilience in provinces. (2) Provinces with a higher number of earthquakes experience more significant effects from earthquake disaster reduction policies. (3) Provinces with higher seismic peak ground acceleration values exhibit more pronounced improvements in seismic resilience.

Early soft tissue response to zirconium oxide and titanium healing abutments in vivo: a study in dogs.

BACKGROUND: This study aimed to investigate the clinical characteristics and early soft tissue response to zirconium oxide (Zr) and titanium (Ti) healing abutments in dogs. METHODS: Eight implants (four at each hemi-mandible) were inserted after bilateral mandibular third and fourth premolars and first molar extraction in dogs. Then, two Zr and two Ti healing abutments were connected to each unilateral mandible eight weeks later. The ligation method was used to create a peri-implant mucositis model and the 24 abutments were divided into four groups: Zr or Ti healing abutments with ligation (ZrL, TiL) or non-ligation (ZrN, TiN). The clinical indices, peri-implant crevicular fluid (PICF), and inflammatory cytokines (TNF-α and IL-1ß) were measured and analyzed on days 0 and 28. The dogs were then sacrificed on day 28, soft tissues around the implants were harvested, and inflammation infiltration was tested by immunohistochemistry. Normal distribution test and two-way analysis of variance was used to analyze the data. RESULTS: The results showed that the clinical indices were similar for Zr and Ti healing abutments. There was significantly more PICF in the ZrL and TiL groups compared to in the ZrN and TiN groups. The TNF-α levels in PICF were significantly different between ZrL and ZrN groups on day 28. And the TNF-α levels in PICF were significantly higher in TiL group on day 28 than that on day 0. However, the number of inflammatory cells was not significantly different between the groups as measured by immunohistochemistry. CONCLUSIONS: These data indicate that soft tissue responses to Zr healing abutments with peri-implant mucositis were comparable to those of Ti healing abutments in vivo, providing a theoretical foundation for the clinical application of Zr abutments.

Local Inflammation Alters MMP-2 and MMP-9 Gelatinase Expression Associated with the Severity of Nifedipine-Induced Gingival Overgrowth: a Rat Model Study.

Nifedipine-induced gingival overgrowth (NIGO) is characterized by cell proliferation and extracellular matrix (ECM) component accumulation in gingival connective tissues, with varying degrees of inflammation and fibrosis. Impaired collagen and ECM homeostasis may be among the underlying molecular mechanisms that lead to the fibrotic changes that occur in drug-induced gingival overgrowth (DIGO). Because matrix metalloproteinases (MMPs) play vital roles in regulating collagen and ECM metabolism, many studies have been performed to reveal the relationship between MMPs and DIGO. It is thought that the gelatinases MMP-2 and MMP-9, both type IV collagenases, are involved in the development of tissue inflammation and organ fibrosis. However, the few studies regarding gelatinase expression in DIGO are controversial. Recent studies have demonstrated the inhibitory effect of cyclosporine A (CsA) on gelatinase expression and/or activity; however, similar changes have yet to be detected in Nif-treated gingival tissues. In this study, we verified that Nif treatment could lead to gingival overgrowth in rats and that gingival inflammation played a pro-proliferative role in NIGO development. Additionally, we examined the temporal expression of gelatinases on days 0, 7, 14, 21, 30, and 40 during NIGO development. The aim was to investigate whether MMP-2 and MMP-9 played significant roles in regulating NIGO development and progression. MMP-2 gene expression was not altered by Nif treatment alone but was significantly inhibited by Nif treatment for 30 days in the presence of local inflammation. However, no significant alterations in MMP-2 protein expression were detected in the Nif-treated gingival tissue, regardless of the presence or absence of local inflammation. Moreover, Nif treatment could lead to transient and significant increases in MMP-9 gene and protein expression levels in the presence of local inflammation. In particular, active MMP-9 expression increased significantly in the gingival tissue that received the combined effect of Nif and ligation treatment; besides, a temporal, but not significant, change was also observed in the gingival tissue that received Nif treatment alone. Taken together, these results provided evidence that temporal changes in MMP-2 and MMP-9 expression occurred during NIGO development. Nif treatment accompanied by local inflammation regulated MMP-2 and MMP-9 expression, primarily MMP-9, which was most likely associated with NIGO severity. Thus, MMP-9 is a potential contributing factor in the process of NIGO development.