Regulation of biomineralization by proteoglycans: From mechanisms to application.

Proteoglycans consist of core proteins and one or more covalently-linked glycosaminoglycan chains. They are structurally complex and heterogeneous. Proteoglycans bind to cell surface receptors, cytokines, growth factors and have strong affinity for collagen fibrils. Together with their complex spatial structures and different charge densities, proteoglycans are directly or indirectly involved in biomineralization. The present review focused on the potential mechanisms of proteoglycans-mediated biomineralization. Topics covered include the ability of proteoglycans to influence the proliferation and differentiation of odontoblasts and osteoblasts through complex signaling pathways, as well as regulate the aggregation of collagen fibrils and mineral deposition. The functions of proteoglycans in mineralization regulation and biomimetic properties render them important components in bone tissue engineering. Hence, the integrated impact of proteoglycans on bone formation was also succinctly deliberated. The potential of proteoglycans to function therapeutic targets for relieving the symptoms of ectopic mineralization and mineralization defects was also comprehensively addressed.

Preventing Early-Stage Graft Bone Resorption by Simultaneous Innervation: Innervated Iliac Bone Flap for Mandibular Reconstruction.

BACKGROUND: Postoperative resorption of vascularized bone grafts jeopardizes the success of dental implant(s) and functional rehabilitation of the jaw. Recent evidence supports the crucial role of innervation in bone regeneration and turnover. METHODS: This study reports a new technique for simultaneous innervation of vascularized iliac flaps in mandibular reconstruction, through neurorrhaphy between ilioinguinal nerves, which innervate iliac bone, and inferior alveolar nerves or great auricular nerves. Twenty-two patients (aged 50 to 69 years) with postoncologic continuity defects of the mandible underwent mandibular reconstruction (10 innervated flaps and 12 control flaps). Graft bone resorption was analyzed by computed tomographic scans at 6 and 12 months postoperatively, and bone quality was evaluated for dental implantation, with histologic and histomorphometric analyses for graft samples. RESULTS: At 12-month follow-up, graft bone density loss in the control group was significantly higher than in the innervated group (p < 0.05). Bone quality evaluation indicated a suitable condition for dental implantation in all patients in the innervated group but in 41.7 percent of patients in the control group. Histologic and histomorphometric analyses showed successful innervation in the innervated group but not in the control group. Osteoclast activity was significantly higher in the control group than in the innervated group (p < 0.05). CONCLUSIONS: Innervated iliac flaps may effectively prevent bone resorption of grafts in mandible reconstruction that otherwise jeopardize the success of dental implants. This new strategy of innervation of bone flaps appears clinically valuable and provides insights into the homeostasis of grafts for functional reconstruction. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.

[Advances in research on lignin biosynthesis and its genetic engineering].

Lignin, one of the main components in vascular plants, is important for the adaptation of terrestrial plants to environment during evolution. However, its presence in plants has negative effects on wood processing during pulping and stock breeding. Therefore much attention has been focused on the regulation of lignin biosynthesis. The pathways leading to the synthesis of lignin polymers have been studied for decades. Much understanding of lignin biosynthesis has been advanced. This paper reviewed the recent progress made in the various steps associated with monolignol biosynthesis. It includes the catalysis by three enzymes, i.e. p-coumarate-3-hydroxylase (C3H), ferulate-5-hydroxylase (F5H) and caffeic acid 3-O-methyltransferase (COMT); the multiform biosynthetic pathway of syringyl (S) lignin in angiosperms; the biosynthesis route of guaiacyl (G) and syringyl (S) lignin specifically regulated by cinnamyl alcohol dehydrogenase (CAD) and sinapyl alcohol dehydrogenase (SAD) and the formation of the lignin macromolecule. Based on the elucidation of lignin biosynthesis pathway, it has also been given the achievements in lignin gene engineering. Many studies were concentrated on the modification of lignin content and composition. In some cases, the potential value of transgenic plants with modified lignin beneficial for pulping has been demonstrated. To better understand the mechanism of lignin biosynthesis and improve the properties of plants, new biotechnological strategies can be developed, which include combinatorial modification of multiple lignin traits in plants through multigene cotransformation, transcriptional control of lignin biosynthesis and the application of RNA interference. The identification of novel genes by molecular and genetic approaches will be useful in opening up new avenues of lignin modification in the future.

[Correction of progressive hemifacial atrophy using dermis-fat graft and Medpor implant shaped by reverse engineering technique].

OBJECTIVE: To evaluate the therapeutic effect of dermis-fat graft combined with Medpor implant shaped by reverse engineering technique in the correction of the progressive hemifacial atrophy. METHODS: A skull model was made by rapid prototyping and the bony deficiency model was acquired with reverse engineering technique. The Medpor implant was shaped precisely based on the deficiency model and implanted with dermis-fat graft at the same stage. RESULTS: 11 cases were treated successfully without infection, necrosis and rejection. The patients were followed up for six months to one year with satisfactory cosmetic improvement. The dermis-fat graft survived without obvious absorption. CONCLUSION: The technique can correct both the bony and soft tissue deficiency for progressive hemifacial atrophy. It is very practical and easily performed with reliant results and less morbidity.

[Comparative effects of essential oil-containing mouthrinse on reduction of plaque and gingivitis].

PURPOSE: The purpose of this study was to determine the efficacy of reducing plaque and gingivitis when used as an adjunct to normal oral hygiene routine and regular professional care. METHODS: Eighty-two adult subjects were enrolled into a 6-month, double-blind, controlled parallel-designed clinical study. After being scaled and polished, they were randomized into two groups: essential oil-containing mouthrinse group and placebo mouthrinse group. Everyone rinsed twice a day for 6 months with 20 mL mouthrinse. The subjects were provided with a soft nylon toothbrush and fluoride toothpaste and were asked not to use any other mouthrinse during the study. At baseline and at 3- and 6-month, subjects were evaluated for supragingival plaque and gingivitis. SPSS 13.0 software package was used for statistical analysis(student's t test). RESULTS: At 3- month, the essential oil-containing mouthrinse significantly produced a 9.02% inhibition of supragingival plaque development and a 11.88% inhibition of gingivitis development compared with the control group. At 6-month, the essential oil-containing mouthrinse significantly produced a 16.98% inhibition of supragingival plaque development and a 21.47% inhibition of gingivitis development compared with the control group. CONCLUSION: The essential oil-containing mouthrinse demonstrates a significant reduction in dental plaque, gingivitis and enhances overall gingival health compared with using placebo rinse.

[Constructing tissue engineered trachea-like cartilage graft in vitro by using bone marrow stromal cells sheet and PLGA internal support: experimental study in bioreactor].

OBJECTIVE: To explore the feasibility of constructing tissue engineered trachea-like cartilage graft in vitro by using bone marrow stromal cells (BMSCs) sheet and PLGA internal support. METHODS: Rabbit BMSCs were expanded and induced by transforming growth factor-1 to improve chondrocyte phenotype of BMSCs. BMSCs sheets were obtained by continuous culture and wrapped the PGLA scaffold in the shape of cylinder. The constructs were incubated in spinner flask for 8 weeks and cartilage formation was investigated by gross inspection, histology, glycosaminoglycan and mechanical strength content. RESULTS: After in vitro culture, cartilage like tissue in cylindrical shape had been regenerated successfully. Stiff, shiny, pearly opalescence tissues were observed. Histological analysis showed engineered trachea cartilage consisted of evenly spaced lacunae embedded in matrix, cells stationed in the lacunae could be noticed clearly. Safranin-O staining on the sections showed homogenous and positive red staining, which demonstrated that the engineered tissue was rich in proteoglycans. CONCLUSIONS: Based on the cell sheet and internal support strategy, trachea-like cartilage in cylindrical shape could be successfully fabricated which provided a highly effective cartilage graft substitute and could be useful in many situations of trachea-cartilage loss encountered in clinical practice.

Dentists' role in treating facial injuries sustained in the 2008 earthquake in China: how dental professionals can contribute to emergency response.

BACKGROUND: A major earthquake struck Sichuan province, China, on May 12, 2008, and the authors were involved in the medical response to the disaster in Jiangyou City, an area hard-hit by the quake. In this article, they analyze data about the earthquake-related facial injuries and assess dentistry's role in treating them. METHODS: This descriptive study included review of medical records for 4,582 patients with earthquake-related trauma at eight hospitals in Jiangyou, a city severely affected by the earthquake, for the day of the disaster and the 14 days immediately afterward. RESULTS: Of the 4,582 patients, 408 (8.9 percent) sustained a total of 482 facial injuries. The dental team treated patients with facial injuries and others who needed care. CONCLUSIONS: Facial injuries constitute a significant portion of earthquake-related trauma, and dentists therefore are an important part of the medical team that deals with such trauma. Dentists are a reliable force in the medical response to earthquakes and other disasters. CLINICAL IMPLICATIONS: The dental team should play an important role in disaster response. Establishing oral and maxillofacial surgeon (OMS)/dentist reserves and active leagues that use OMSs' and general dentists' offices as bases can help improve disaster response.

Histological evaluation and surface componential analysis of modified micro-arc oxidation-treated titanium implants.

The objective of this study is to investigate soft tissue and bone tissue reaction to titanium implants treated by a modified micro arc oxidation (MAO) technique, and analyze the surface components and implant-bone contact ratio by animal experiments to evaluate the osseointegration condition of implants with this modified MAO surface. MAO titanium plates were installed subcutaneously in rabbits. Tissue reaction was evaluated by HE sections. MAO titanium implants designed for endosseous examination were installed in Beagles' femurs. Bone tissue surrounding implants was analyzed histologically. Surfaces of retrieved implants were observed and examined by SEM and EDX. All procedures were performed under the control of untreated pure titanium implants. Thin homogeneous fibrous envelope could be found without apparent inflammation cells infiltration around the subcutaneously imbedded MAO titanium plates, which was almost same as control group. Fast osteoid deposition comprising high content of calcium, phosphor, carbon, and nitrogen elements was found on the retrieved MAO implant surfaces, while comparatively less amount of carbon and nitrogen elements were found on the retrieved implants of control group. Matured bone tissue comprising bone trabeculae and Haversian canals appeared in 8 weeks, while it took 12 weeks needed to form matured bone tissue in control group. In conclusion, MAO titanium materials shows good biocompatibility and calcium phosphate inducement capability in vivo and could accelerate bone tissue growth and shorten the osseointegration time.