A prospective comparative study between differential moments and miniscrews in anchorage control

Abstract

The purpose of this study was to measure the efficacy of anchorage control between differential moments mechanics and temporary anchorage devices in a clinical trial. Forty-six patients requiring extraction of maxillary first premolars were allocated into 2 treatment groups. The differential moments group (G1) received a nickel titanium (NiTi) intrusion arch and a 150g NiTi closing coil spring for separate canine retraction, followed by a continuous mushroom loop archwire for the retraction of the incisors. The TAD group (G2) received one miniscrew placed between maxillary second premolars and first molars with a 150 g NiTi closing coil spring connecting the miniscrew to a hook placed in the archwire between the lateral incisor and canine. Lateral cephalograms were taken before (T1) and after incisor retraction (T2). The ratio of molar protraction to incisor retraction was calculated and intragroup and intergroup changes in upper lip, maxillary incisor and molar position were analyzed by paired and independent t-tests. Twenty-eight patients were analyzed after 18 patients did not receive the intervention, were lost to follow-up, or discontinued treatment. The ratio of molar protraction to incisor retraction in G1 was 0.44 and in G2 was -0.11, which was significantly different. There was a statistically significant change in upper lip from T1 to T2 but no difference between the two groups. Moreover, there was a significant distal molar tipping and lingual incisor tipping in G2. There is a significant difference in the amount of anchorage control using differential moments mechanics compared to TADs. Although statistically significant retraction of upper lip was observed in both groups, there was no significant difference between the two groups.

A comparative anchorage control study between conventional and self-ligating bracket systems using differential moments

“…Most studies report on the initial and final molar position based on the lateral cephalometric radiographs taken at those points in treatment. Davoody et al 6 measured exactly the molar anchorage loss with differential moments after alignment and completion of space closure, finding, on average, 2.55 mm of maxillary mesial molar movement. Based on this finding one could presume that about 1 mm of molar anchorage loss may be expected during the alignment phase.…”

“…This concept of differential moments was later applied to a continuous straight wire to control posterior anchorage during canine retraction with minimal anchorage loss. [6][7][8] Friction in sliding mechanics has drawn a lot of attention, especially as it pertains to effectiveness and efficiency in orthodontic tooth movement. Studies have explored various factors that can affect friction during sliding mechanics in an in vitro setting.…”

“…The following differential moments mechanics were used in both groups for space closure, according to Davoody et al 6 Briefly, a prefabricated 0.017 3 0.025-inch NiTi intrusion arch was tied over the 0.016-inch 3 .0.022-inch base stainless steel archwire in the maxillary arch. The intrusion arch was tied mesial to the lateral incisors, delivering a tipback moment on the molars and an intrusive force to the anterior teeth.…”

Response of the maxillary dentition to a statically determinate one-couple system with tip-back mechanics: A prospective clinical trial

“…The anteroposterior and vertical measurements of the maxillary molars on the lateral cephalogram were registered at the jigs' insertion site on the molar auxiliary tube. 6 To evaluate the maxillary dental changes, all of the radiographs were hand traced and superimposed from the described three time points. 6 The maxillary superimpositions were performed on the internal palatal surfaces of the maxilla.…”

Une orthodontie contemporaine fondée sur l'harmonie esthétique et sur la biomécanique. Un entretien avec Ravindra Nanda

“…: Vous avez consacré de nombreuses publications [12,22,32,55,68,[70][71][72][73]87] et un ouvrage [50] aux ancrages orthodontiques temporaires. Comme pour tout dispositif mécanique, leur utilisation peut s'accompagner d'effets indésirables.…”