ABSTRACT
BACKGROUND:Scaffold materials are the important part of tissue engineering bone, and the ideal biodegradation speed of the scaffold materials can be in accordance with the regeneration speed of bone formation in order to achieve a long-term stability. OBJECTIVE:To summarize the biodegradability of different types of currently available scaffold materials and its relationship with bone formation. METHODS:The PubMed and CNKI database were searched by the first author using the key words of “tissue engineering bone, composite scaffold, scaffold degradation” in English and Chinese for articles addressing biodegradability of scaffold materials and its relationship with bone formation published during January 1996 and December 2013. RESULTS AND CONCLUSION:Many scaffold materials under organic, inorganic and organic-inorganic categories have been available and the current studies focus on inorganic materials and organic-inorganic composite materials.In vivo andin vitro studies indicate the different characteristics and relative merits of these scaffold materials. Organic materials have a relatively slow degradation rate while inorganic materials can completely degrade but have an insufficient mechanical property. For organic-inorganic composite materials, further studies are needed.
ABSTRACT
This study is designed to theoretically evaluate the treatment effects of MEAW with tip back bends on the mandible dentition when used as a finishing archwire without elastic and with long class III elastics respectively, and to compare them with those of stainless-steel wire and shape-memory wire. The finite element analysis (FEA) method was adopted and the findings were as follows: (1) In the case of no elastics, the MEAW rotates the second premolar, the first molar and the second molar distally while rotating other teeth mesially, and depresses anterior teeth. However, the stainless-steel wire and the shape-memory wire rotate molars distally while rotating other teeth mesially. Furthermore, they extrude anterior teeth and depress posterior teeth. (2) The MEAW with tip back bends and long class III elastics inclines and rotates posterior teeth more distally than the MEAW with only tip back bends does. In the case of tip back bends and long class III elastics loaded together, the shape-memory wire inclines teeth in greater strength as compared with the stainless-steel wire. (3) The stress level of tooth root is the lowest with MEAW, the highest with stainless-steel wire, and is middle with the shape-memory wire. From these results, it is suggested that: (1) The MEAW therapy technique is effective for leveling the curve of Spee and regulating tooth respectively. (2) The MEAW therapy technique can transfer therapy force efficiently. (3) The MEAW is considered to be suitable for treating openbite malocclusion to make the posterior teeth upright because it effectively rotates teeth distally through the force of posterior bends and long class III elastics. (4) The loaded force on the teeth is more soft and permanent in the MEAW than in the stainless-steel wire and the shape-memory wire.
Subject(s)
Humans , Biomechanical Phenomena , Finite Element Analysis , Imaging, Three-Dimensional , Malocclusion , Therapeutics , Orthodontic Appliance Design , Orthodontic Brackets , Orthodontic Wires , Orthodontics, Corrective , Methods , Tooth Movement TechniquesABSTRACT
Objective:To evaluate the effect of segmental approach in the treatment of Angle class Ⅱ division 1 malocclusion.Methods:7 cases of classⅡ,division 1 maloclusion were treated.Upper first premolar and lower second premolars were extracted in all cases.Lower first molars were mesially moved by means of segmental arch. Cephalometric analysis was used to evaluate the effects of the treatment.Results:Facial profile improvement and lower anterior facial height maintenance were achieved.The occlusion plane angle,mandibular plane angle were well controlled with lower anterior teeth upright on the lower basal bone.All patients represented good mandible response.Conclusion:Segmental technique is a simple and effective approach in correcting class Ⅱ,division 1 maloclusion
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Objective:To evaluate the reliability of localization of the impacted teeth by assessing various conventional radiographies. Methods:32 patients with impacted teeth were included. The impacted teeth were localized by conventional roentgenographic techniques including panoramic radiography (PR) and linear tomography (LT).Results:Dentomaxillary orthopantomographic solution (PR,LT and PR combined with LT) clearly presented the position of the impacted teeth. Serial cross-section linear tomography also ensured the shape and axis of the impacted teeth captured on the radiograph. The accuracy of the localization was further verified by the surgical exposure in 5 cases. Conclusion:Orthopantomographic assessing can directly and precisely localize the buccal and lingual position of the impacted teeth.