Polyetheretherketone (PEEK) is a new material used for the frameworks of removable partial dentures (RPD). The questions whether the PEEK framework has similar stress distribution on oral tissue and displacement under masticatory forces as titanium alloy (Ti-6Al-4V) or cobalt-chromium alloy (CoCr) remain unclear and worth exploring. A patient’s intraoral data were obtained via CBCT and master model scan. Four RPDs were designed by 3Shape dental system, and the models were processed by three-dimensional finite element analysis. Among three materials tested, PEEK has the lowest maximum von Mises stress (VMS) on periodontal ligament (PDL), the greatest maximum VMS on mucosa, the maximum displacement on free-end of framework, and the lowest maximum VMS on framework. Results suggested that PEEK framework has a good protective effect on PDL, suggesting applications for patients with poor periodontal conditions. However, the maximum displacement of the free-end under masticatory force is not conducive for denture stability, along with large stress on the mucosa indicate that PEEK is unsuitable for patients with more loss of posterior teeth with free-end edentulism.

Although in vivo studies have shown that low-magnitude, high-frequency (LMHF) vibration (LM: < 1 ×g; HF: 20-90 Hz) exhibits anabolic effects on skeletal homeostasis, the underlying cellular/molecular regulation involved in bone adaptation to LMHF vibration is little known.In this report, we tested the effects of microvibration (magnitude: 0.3 ×g, frequency: 40 Hz, amplitude: ±50 μm, 30 min/12 h) on proliferation and osteodifferentiation of bone marrow-derived mesenchymal stromal cells (BMSCs) seeded on human bone-derived scaffolds. The scaffolds were prepared by partial demineralisation and deproteinisation. BMSCs were allowed to attach to the scaffolds for 3 days. Morphological study showed that spindle-shaped BMSCs almost completely covered the surface of bone-derived scaffold and these cells expressed higher ALP activity than those cultured on plates. After microvibration treatment, BMSC proliferation was decreased on day 7 and 10; however, numbers of genes and proteins expressed during osteogenesis, including Cbfa1, ALP, collagen I and osteocalcin were greatly increased. ERK1/2 activation was involved in microvibration-induced BMSC osteogenesis. Taken together, this study suggests that bone-derived scaffolds have good biocompatibility and show osteoinductive properties. By increasing the osteogenic lineage commitment of BMSCs and enhancing osteogenic gene expressions, microvibration promotes BMSC differentiation and increase bone formation of BMSCs seeded on bone-derived scaffolds. Moreover, ERK1/2 pathway plays an important role in microvibrationinduced osteogenesis in BMSC cellular scaffolds.Keywords: Bone-derived scaffold, bone marrow-derived mesenchymal stromal cells, microvibration, osteogenesis, ERK1/2. *Address for correspondence: Haiyang Yu West China Hospital of Stomatology Sichuan University Chengdu, 610041, P.R. China Telephone/FAX Number: 86-028-85502869 E-mail: yhyang6812@scu.edu.cn IntroductionCurrent consensus for bone tissue engineering includes three essential elements, i.e., biomaterial scaffold, osteogenic cell lineage and bone inducing factors (e.g., mechanical stimulus, Ashammakhi and Ferretti, 2003; Khan et al., 2005;Mistry and Mikos, 2005). Scaffold materials should provide the support for cell attachment and have osteoinductive property (Langer and Vacanti, 1993;Ashammakhi and Ferretti, 2003). Due to the limited supply and donor-site morbidity of autogenous bone grafts, different physical structures and insuffi cient osteoinductive ability of synthetic materials (Ashammakhi and Ferretti, 2003;Silber et al., 2003), scaffolds derived from different individuals (allografts) and species (xenografts) provide a promising resource and approach to address the signifi cant drawbacks of existing scaffolds, because these scaffolds have similar structures to autogenous bone (Salkeld et al., 2001;Simion et al., 2004). Additionally, with the proper chemical and physical process on these bone materials, including demineralisation and deproteinisation (Tadjoedin et al., 2003;Xu et al., 2003...

By removing a part of the structure, the tooth preparation provides restorative space, bonding surface, and finish line for various restorations on abutment. Preparation technique plays critical role in achieving the optimal result of tooth preparation. With successful application of microscope in endodontics for >30 years, there is a full expectation of microscopic dentistry. However, as relatively little progress has been made in the application of microscopic dentistry in prosthodontics, the following assumptions have been proposed: Is it suitable to choose the tooth preparation technique under the naked eye in the microscopic vision? Is there a more accurate preparation technology intended for the microscope? To obtain long-term stable therapeutic effects, is it much easier to achieve maximum tooth preservation and retinal protection and maintain periodontal tissue and oral function health under microscopic vision? Whether the microscopic prosthodontics is a gimmick or a breakthrough in obtaining an ideal tooth preparation should be resolved in microscopic tooth preparation. This article attempts to illustrate the concept, core elements, and indications of microscopic minimally invasive tooth preparation, physiological basis of dental pulp, periodontium and functions involved in tool preparation, position ergonomics and visual basis for dentists, comparison of tooth preparation by naked eyes and a microscope, and comparison of different designs of microscopic minimally invasive tooth preparation techniques. Furthermore, a clinical protocol for microscopic minimally invasive tooth preparation based on target restorative space guide plate has been put forward and new insights on the quantity and shape of microscopic minimally invasive tooth preparation has been provided.

Oxygen deficiency is associated with various oral diseases, including chronic periodontitis, age-related alveolar bone loss, and mechanical stress-linked cell injury from orthodontic appliances. Nevertheless, our understanding of the impact of hypoxia on periodontal tissues and its biochemical mechanism is still rudimentary. The purpose of this research was to elucidate the effects of hypoxia on the apoptosis of human periodontal ligament stem cells (PDLSCs) in vitro and the underlying mechanism. Herein, we showed that cobalt chloride (CoCl) triggered cell dysfunction in human PDLSCs in a concentration-dependent manner and resulted in cell apoptosis and oxidative stress overproduction and accumulation in PDLSCs. In addition, CoCl promoted mitochondrial fission in PDLSCs. Importantly, CoCl increased the expression of dynamin-related protein 1 (Drp1), the major regulator in mitochondrial fission, in PDLSCs. Mitochondrial division inhibitor-1, pharmacological inhibition of Drp1, not only inhibited mitochondrial fission but also protected against CoCl-induced PDLSC dysfunction, as shown by increased mitochondrial membrane potential, increased ATP level, reduced reactive oxygen species (ROS) level, and decreased apoptosis. Furthermore, N-acety-l-cysteine, a pharmacological inhibitor of ROS, also abolished CoCl-induced expression of Drp1 and protected against CoCl-induced PDLSC dysfunction, as shown by restored mitochondrial membrane potential, ATP level, inhibited mitochondrial fission, and decreased apoptosis. Collectively, our data provide new insights into the role of the ROS-Drp1-dependent mitochondrial pathway in CoCl-induced apoptosis in PDLSCs, indicating that ROS and Drp1 are promising therapeutic targets for the treatment of CoCl-induced PDLSC dysfunction.

.Cystic echinococcosis (CE), also known as hydatid cyst, is a zoonosis caused by the tapeworm Echinococcus granulosus. It is a common health problem in many countries. This condition predominantly affects the liver and the lungs, and the spleen to a less extent (splenic hydatid cyst, SHD). Indeed, it is estimated that SHD occurs in less than 2% of abdominal CE and 0.5–8% of CE cases. Here, we present a case of a 44-year-old Chinese woman with primary giant SHD who experienced pain in the left hypochondrium for 10 days. A combination of abdominal ultrasonography and computed tomography (CT) were used for preoperative diagnosis. Laparoscopic splenectomy was performed without any complications, and albendazole (400 mg per day) was administered postoperatively for 3 months. At 3-, 6-, 12-, and 24-month follow-up, the patient remained symptoms free, and abdominal CT found no signs of recurrence. In addition to this case, we review the previous literature on SHD treated by laparoscopy and reveal that laparoscopic approach is safe and effective for SHD. Particularly, we show that laparoscopic splenectomy is feasible for giant cysts (> 10 cm) at high risk of rupture or compressing other vital structures.