Laser ablation of hard tissue allows very precise pre-programmed incisions with complete free geometry and it has advantage of leaving no tissue damages. Those disadvantages of thermal side effects and low cutting rates had been overcome by introducing ultra-short pulses and ultra-power laser systems. This review highlights the recent advances in the laser ablation of hard tissues.

Object To develop a method for the identification of Fritillaria walujewii Regel by UV spectrum. Methods UV spectrum of the absolute alcoholic extract of F. walujewii was determined and compared with that of four other similarly treated Fritillaria species. Results The UV spectrum of F. walujewii was consistently different with that of the other four species. Conclusion UV spectrum can be used to differentiate F. walujewii from other species of Fritillaria.

Bone and Bones ; Humans ; Mandible ; Osteogenesis, Distraction

BACKGROUND:Osteoporosis is characterized by low bone mineral density and/or poor bone microarchitecture leading to an increased risk of fractures. Oral manifestations can be frequently discovered in osteoporosis patients. Osteoporosis therapies have mostly relied on antiresorptive drugs. Parathyroid hormone plays a significant role in osteogenesis and calcium deposition. Intermittent exposure to parathyroid hormone has been widely proved to lead to a net increase in bone formation.
OBJECTIVE: To discuss the possibly celular and molecular mechanism of parathyroid hormone in strengthening the bone mineral density and regulating bone formation.
METHODS: An online search of CNKI and Medline databases was performed for relevant articles using keywords of “parathyroid hormone; osteoporosis; osteoblast; osteogenesis” in Chinese and English, respectively. Relevant articles were summarized from three aspects: effects of parathyroid hormone on differentiation and proliferation of osteoblasts, effects of parathyroid hormone on osteoblast apoptosis, and the relationship of parathyroid hormone with Wnt/beta-catenin pathway and other cytokines. According to inclusion criteria, 41 articles were retained at last.
RESULTS AND CONCLUSION:Parathyroid hormone exerts an effect on parathyroid hormone type I receptor, triggering a classic G protein signaling pathway. Parathyroid hormone mainly works through protein kinase A signaling pathway, adjusting its downstream c-reactive protein. Intermittent use of parathyroid hormone can increase osteoblast proliferation, increase osteoblast runx2 and osteocalcin at mRNA and protein levels, inhibit osteoblast apoptosis by against oxidative stress, so as to promote osteogenesis.

Adult chondrocytes had been used as seed cells in the previous tissue engineering; however, they possess the weaknesses including the limited proliferative capability in vitro and the liability to aging after amplification. Bone marrow stromal cells (BMSCs) are multipotent cells, which can differentiate into osteoblasts, chondrocytes, and adipocytes. It is of great importance to study the regulation and control of BMSC directed induction because directed differentiation is required in the tissue engineering. During the BMSC differentiation towards chondrocytes, serious kinds of biological inducing factors participate in precise induction as signal factors. The physical factors, such as biomechanical strength and ultrasound, have been shown to be involved in the regulation of BMSC differentiation towards chondrocytes. In terms of tissue repair, apart from biological factors which play an important role in the formation of cartilage tissue, the chondrocyte microenvironment in vivo is indispensable. Bioreactor is a kind of device intended for in vitro tissue culture that incubates the cells or tissues taken from living bodies in simulated physiological environment in vivo. On the basis of original cell culture, the present bioreactors apply biomechanical stimulation to simulate the stressed environment of articular cartilage in vivo.

BACKGROUND:3D bioprinting has been used to print a variety of tissues including skin,vascular tissues,liver,cartilage,cardiac tissues,ear,and adipose tissues.OBJECTIVE:To review the application of 3D bioprinting technology in printing tissues or organs and its research progress in oral medicine.METHODS:A computer-based retrieval of PubMed and CNKI was performed to search articles concerning the application of 3D bioprinting technology in printing tissues,organs and stomatology which were published from 2006 to 2016,using the keywords of 3D bioprinting,3D pinting,organs,tissues,tissue engineering,stomatology,oral,cranio-maxillofacial in English and Chinese,respectively.RESULTS AND CONCLUSION:Direct cell-bioprinting is still in its early stage,even though 3D bioprinting has been applied to print various tissues such as skin,vascular tissues,liver,cartilage and cardiac tissues,etc.Although additive manufacturing technology has been widely used for printing different scaffolds of tissues and organs nowadays,there are no successful bioprinted tissues with biological functions in clinical practice.Even in oral medicine,most of the studies still remain in the stage of printing biological scaffolds.It is a long way to solve the problems such as source of cells,materials of biological scaffolds and types of extracellular matrix in the future,due to the complexity of human organism structure and the function expression of various tissues and organs.

BACKGROUND:Bioceramic has similar components compared to human bone tissue and it has shown good ostoconductivity both in vitro and in vivo.Meanwhile,it is biocompatible.So,bioceramics is considered as one of the most promising materials which can be applied to bone tissue engineering.OBJECTIVE:To summarize the properties of bioceramics and the research progress in experimental studies and clinical applications.METHODS:PubMed was searched for relevant articles published during 2000 to 2016 with the key words of bioceramics,hydroxylapatite,calcium phosphate,bioglass,bone tissue engineering in English.RESULTS AND CONCLUSION:Bioceramic materials can be divided into two categories:calcium phosphates and bioactive glass.Calcium phosphates have good biocompatibility and osteoconductivity,while the mechanical property is not so satisfying.Bioactive glass is biocompatible and beneficial to the expression of some osteogenic genes,but it is brittle and weak.Some kinds of bioceramics have already been applied to clinical practice.In recent years,calcium phosphates have also been used as coated materials to improve the properties of tissue-engineered scaffolds.Bioceramics combined with synthetic polymers,shows better mechanical performance and biodegradation.Even so,it still has plenty of problems and challenges as a widely used bone repair material in clinical practice.

Objective To summarize the clinical features and possible impacts of Goodpasture's syndrome in pregnancy on the pulmonary and kidney of the newborn and the mothers. Methods One patient diagnosed Goodpasture's syndrome in pregnancy hospitalized in Peking Union Medical College Hospital on August 23 in 2011 delivered a neonate with bullae of lung. And literatures including 8 cases of pregnancy complicated by Goodpasture's syndrome worldwide through Medline were reviewed. Results (1) Case report:one 31-year-old women presented with acute renal failure at 30+6 weeks of gestation and delivered a male infant with birth weight 1 900 g by caesarean section at 31+1 weeks of gestation. Diagnosis was confirmed as Goodpasture's syndrome with anti-glomerular basement membrane(GBM) antibodies in serum and renal biopsy after delivery. Then she was treated with methylprednisolone, cyclophosphamide, plasmapheresis and dialysis. The neonate showed the lung bullae in the right middle lobe and bilateral intraventricular hemorrhage but renal function was transient normal with anti-GBM as 113.1 EU/ml. The baby was treated by glucocorticoid for two months and clinical symptoms were improved. Anti-GBM antibodies and chest CT showed normal. After been followed up for two years, the baby was normal. (2) Literatures review:the main manifestations of Goodpasture's syndrome in pregnancy were malignant hypertension and renal failure but respiratory symptoms were not obvious. Treated with plasmapheresis, hematodialysis and glucocorticoid maybe have good effects. Most cases had premature delivery. Neonatal anti-GBM antibodies coming from mothers could result to cerebral, renal and pulmonary injury which could be treated by glucocorticoid. Conclusions The Clinical features of pregnancy complicating the Goodpasture's syndrome are malignant hypertension and renal failure. Diagnosis was depended on positive anti-GBM antibodies and renal pathological changes and treatment were depended on plasmapheresis, hematodialysis and glucocorticoid. Neonatal cerebral, renal and pulmonary injury resulting from anti-GBM antibodies coming from mothers should be followed up, and glucocorticoid should be taken if necessary.

BACKGROUND: Cryopreservation can decrease tissue and organ immunogenicity. The effects of cryopreservation on cell immunogenicity are disputed.OBJECTIVE: To investigate the effects of liquid nitrogen cryopreservation on osteoblast immunogenicity. DESIGN: Randomized,controlled ,paired-sample experiment. SETTING: This study was performed in the Laboratory Center, Qilu Hospital Affiliated to Shandong University between July 2003 and March 2004. MATERIALS: Four New Zealand rabbits of either gender were included for this study. 3H-TdR was provided by Nuclear Medicine Institute of Shandong University. METHODS: Osteoblasts were cultured from the tibial periosteum of New Zealand rabbits and then cryopreservated in the liquid nitrogen for 3 months and defrosted. Cryopreservated and thawn osteoblasts were set as cryopreserved group and freshly cultured osteoblasts were set as non-cyropreserved group. Major histocompatibility complex (MHC)-I positive rate was examined by flow cytometry assay prior to and after cryopreservation. Simultaneously, mixed lymphocyte-osteoblast cultures were established. Lymphocyte stimulation index was calculated after counting the flares using β liquid scintilloscope. MAIN OUTCOME MEASURES: MHI-I antigen positive rate and lymphocyte stimulation index prior to and after cryopreservation of osteoblasts. RESULTS: MHI-I antigen positive rate and lymphocyte stimulation index of osteoblasts was significantly higher in the non-cryopreserved group than in the cryopreserved group (P＜0.01). CONCLUSION: The immunogenicity of cryopreserved osteoblasts was significantly decreased. Liquid nitrogen cryopreservation is an ideal method to decrease the immunogenicity of osteoblasts.

Objective To apply the three-dimensional pre-operative simulation and intra-operative real-time navigation in the reconstruction of old maxillofacial fractures so as to increase the surgical precision. Methods Six patients with old maxillofacial fractures were enrolled, and the diagnosis of unilateral old maxillofacial fractures was confirmed by clinical and imaging examinations. Virtual three-dimensional skull models were reconstructed from pre-operative CT images. The fractured bone was moved or rotated, and was reposed in a desired site according to the mirrored part from the healthy side. After patient-to-image registration, the surgical instruments and patients were tracked in real-time by optical tracking system during operation, and in this way the maxillofacial fractures were reposed satisfactorily guided by the virtual image. Results Three-dimensional simulation before operation and real-time navigation of patients and instruments during operation were realized. The error of registration was less than 1 mm. The post-operative CT examinations of these six patients revealed that the fracture reposition was same to the pre-operative planning, and the difference between them was less than 1.5 mm. The operations were minimally-invasive, with no complications. Conclusion Computer-aided surgical simulation and navigation system can effectively increase the surgical precision of reconstruction of old maxillofacial fractures.