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OBJECTIVE To discuss the difficulties in t he development of complex preparations and puts forward solutions ，in order to provide some reference for the development and preparation of complex preparations. METHODS Based on the development status of complex preparations ，the challenges faced by the development of complex preparations were analyzed ，and the countermeasures for the development of complex preparations were proposed. RESULTS & CONCLUSIONS The development of complex preparations required high quality of personnel ，and was limited by pharmaceutical excipients ，delivery devices and pharmaceutical equipment. The preparation process was complex ，there were many quality control parameters and patent barriers. Complex preparation development enterprises need to pay more attention to talents ，pharmaceutical excipients ，delivery devices and pharmaceutical equipment ，and clarify the impact of key technology on preparation production and quality characteristics ；in addition，they need to strengthen independent research and development ，crack the patent layout of original research enterprises and protect their own innovative achievements. Domestic complex preparation development enterprises can combine imitation and innovation to develop complex preparation products with independent brands to better meet the needs of patients.
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INTRODUCTION: Eliminating the residual debris and bacteria in the root canal system is one of the main purposes of the endodontic treatment. However, the complexity on the anatomy of the root canal system makes it difficult to eliminate the bacterial biofilm existing along the root canal surface and necrotic pulp tissue by mechanical instrumentation and chemical irrigation. Recently, more effective irrigant delivery systems for root canal irrigation have been developed. The purpose of this review was to present an overview of root canal irrigant delivery techniques and devices available in endodontics. REVIEW: The contents of this paper include as follows; - syringe-needle irrigation, manual dynamic irrigation, brushes - sonic and ultrasonic irrigation, passive ultrasonic irrigation, rotary brush, RinsEndo, EndoVac, Laser CONCLUSION: Though technological advances during the last decade have brought to fruition new agitation devices that rely on various mechanisms, there are few evidence based study to correlate the clinical efficacy of these devices with improved outcomes except syringe irrigation with needle and ultrasonic irrigation. The clinicians should try their best efforts to deliver antimicrobial and tissue solvent solutions in predictable volumes safely to working length.