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

Abstract

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.

3D quantification of in vivo orthodontic tooth movement in rats by means of micro-computed tomography

“…In group 2 (n = 6), a self-drilling mini-screw (2.5 × 1.3 × 5 mm, Dewimed, Tuttlingen, Germany) was placed in the alveolar bone, 2 mm distal to the incisors in one random side of the maxilla. The area was allowed to heal for 3 weeks to assure stability [14]. A 25cN Sentalloy closed coil spring was attached between M1 and the miniscrew by passing a metallic ligature through its eyelet.…”

Dynamic Changes in Tooth Displacement and Bone Morphometry in Orthodontic Tooth Movement in Rats: A 3D Analysis

“…Brie y, on one randomly-allocated side of the maxilla, a self-drilling mini-screw (2.5 mm x 1.3 mm x 5 mm, DEWIMED, Tuttlingen, Germany) was implanted in the alveolar bone, approximately 2 mm distal to the upper incisors and with an angulation of 45° to the occlusal plane, in order to provide bone anchorage. Healing time of 3 weeks was allowed to ensure stability [20] . Afterwards, a constant orthodontic force (OF) of 25 cN was loaded between the mini-screw and the upper rst molar by using a Sentalloy closed coil spring (Ultralight, Dentsply GAC, Rochecorbon, France) (Figure 1A).…”