Abstract
ObjectiveTo compare dental and skeletal anchorages in mandibular canine retraction by means of a stress distribution analysis. MethodsA photoelastic model was produced from second molar to canine, without the first premolar, and mandibular canine retraction was simulated by a rubber band tied to two types of anchorage: dental anchorage, in the first molar attached to adjacent teeth, and skeletal anchorage with a hook simulating the mini-implant. The forces were applied 10 times and observed in a circular polariscope. The stresses located in the mandibular canine were recorded in 7 regions. The Mann-Whitney test was employed to compare the stress in each region and between both anchorage systems. The stresses in the mandibular canine periradicular regions were compared by the Kruskal-Wallis test. ResultsStresses were similar in the cervical region and the middle third. In the apical third, the stresses associated with skeletal anchorage were higher than the stresses associated with dental anchorage. The results of the Kruskal-Wallis test showed that the highest stresses were identified in the cervical-distal, apical-distal, and apex regions with the use of dental anchorage, and in the apical-distal, apical-mesial, cervical-distal, and apex regions with the use of skeletal anchorage. ConclusionsThe use of skeletal anchorage in canine retraction caused greater stress in the apical third than the use of dental anchorage, which indicates an intrusive component resulting from the direction of the force due to the position of the mini-implant and the bracket hook of the canine.
Highlights
IntroductionMany resources have been used with the purpose of avoiding undesired movement of the anchoring unit, namely: headgear appliances, lingual arches and transpalatal bars
The concern over anchorage has always accompanied the evolution of Orthodontics
The stresses associated with skeletal anchorage were significantly higher than the stresses associated with dental anchorage (P < 0.05)
Summary
Many resources have been used with the purpose of avoiding undesired movement of the anchoring unit, namely: headgear appliances, lingual arches and transpalatal bars. Some approaches to anchoring consider the biological basis and avoid mobility of posterior teeth before space closure. In these cases, rigid appliances are combined with monitoring of the occlusion in order to achieve anchoring.[1] Strategies such as including the second molar in the mechanics, using low forces for retraction and low friction mechanics have already been suggested to minimize loss of anchorage.[2] Despite the availability of several papers studying anchorage, due to methodological issues, the scientific evidence is not considered sufficient to identify the most effective anchoring system.[3]
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