Mechanical Alternatives for Molars Uprighting. Force Systems Released by Appliances

Tatsuko SAKIMA, Lidia Parsekian MARTINS, Mauricio Tatsuei SAKIMA, Hélio Hissashi TERADA, Roberto Yoshio KAWAKAMI, Terumi Okada OZAWA

In the clinical routine we frequently come across mesially tipped molars due to the early loss of deciduous and permanent molars, missing second premolars, ectopic eruption and prolonged use of lip bumper or extraoral appliance, frequently causing impaction of sencond and third molars. Usually, the mesially tipped molars develop infrabony defects in their mesial area and the decrease of the interradicular space in their distal area. Molar uprighting with space openning or closure or even its extraction are the recommended solutions, depending on the severity of the problem. Molar uprighting movement is difficult to perform without extrusion and frequently produces premature occlusal contacts and also bite openning. Some segmented arch appliances advocated by Burstone, Melsen, Marcotte and other authors provide a mechanical control with well defined theoretical bases, mainly on the extrusion/intrusion movement of molars, with a few undesirable effects. The aim of this article is to present the different types of uprighting appliances, showing the mechanical principles and the side effects, describing the proper biomechanics for each situation.

Keywords: Biomechanics. Molar uprighting. Segmented arch. Intrusion. TMJ. NITI.

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