Evaluation of the long-term stability of micro-screws under different loading protocols: a systematic review

• Published in: Brazilian oral research Vol. 33; p. e046
• Main Authors: Zhang, Jia-Nan, Lu, Hai-Ping, Bao, Xi-Chen, Shi, Yuan, Zhang, Meng-Han
• Format: Journal Article
• Language: English
• Published: Brazil Sociedade Brasileira de Pesquisa Odontológica - SBPqO 01.01.2019; Sociedade Brasileira de Pesquisa Odontológica
• Subjects: Animal Experimentation; Animals; Biomechanical Phenomena; Bone Screws; Bone Screws - standards; Dental Implantation - instrumentation; Dental Implantation - methods; Dental Implants - standards; DENTISTRY, ORAL SURGERY & MEDICINE; Equipment Design; Models, Animal; Orthodontic Anchorage Procedures - instrumentation; Orthodontic Anchorage Procedures - methods; Reference Values; Reproducibility of Results; Time Factors; Treatment Outcome; Workload Stability; Wound Healing; Bone Screws; Workload Stability; Animal Experimentation
• ISSN: 1806-8324; 1807-3107; 1807-3107
• DOI: 10.1590/1807-3107bor-2019.vol33.0046

The aim of this systematic review was to investigate the association between the different factors of loading protocols and the long-term stability of micro-screws from biomechanical and histological viewpoints. Searches were performed on PubMed, Embase, Cochrane Library, Wanfang and CNKI databases for animal experiments comparing loading protocols and the long-term stability of micro-screws. Among 1011 detected papers, 16 studies met the eligibility criteria and were selected for analysis. Most studies showed medium methodological quality for evaluation of micro-screws' long-term stability. Five studies reported that loading would not destroy the long-term stability of micro-screws. Three studies indicated that low-intensity immediate loading or a 3-week minimal healing time was acceptable. Two studies reported that the loading magnitude was a controversial issue with regard to the micro-screws' long-term stability. Two studies suggested that counterclockwise loading could decrease the long-term stability of micro-screws. In conclusion, immediate loading below 100g force, healing time greater than 3 weeks, regular loading below 200g force and a clockwise direction of force supported the long-term stability of micro-screws. Further studies relating to the combination of varying loading conditions will be needed.