Early vs late orthodontic treatment of tooth crowding by first premolar extraction: A systematic review.

Objective: To investigate the body of evidence in the literature about the most favorable time for initiating orthodontic treatment in patients with severe crowding caused by tooth size arch length deficiency (TSALD).

Materials And Methods: Electronic databases (PubMed, Ovid Medline, Scopus, Virtual Health Library, and The Cochrane Library) were searched for articles published between 1900 and April 2014. Studies were included that evaluated treatment of patients with severe crowding caused TSALD, who were treated with first premolar extraction.

Corrosion behavior of self-ligating and conventional metal brackets.

Objective: To test the null hypothesis that the aging process in self-ligating brackets is not higher than in conventional brackets.

Methods: Twenty-five conventional (GN-3M/Unitek; GE-GAC; VE-Aditek) and 25 self-ligating (SCs-3M/Unitek; INs-GAC; ECs-Aditek) metal brackets from three manufacturers (n = 150) were submitted to aging process in 0.9% NaCl solution at a constant temperature of 37 ± 1°C for 21 days.

Colour stability of aesthetic brackets: ceramic and plastic.

Background: The colour stability of aesthetic brackets may differ according to their composition, morphology and surface property, which may consequently influence their aesthetic performance.

Aims: To assess the colour stability of aesthetic brackets (ceramic and plastic) after simulating aging and staining.

Methods: Twelve commercially manufactured ceramic brackets and four different plastic brackets were assessed.

Incorporation of metal and color alteration of enamel in the presence of orthodontic appliances.

Objective: To test the null hypothesis that it is not possible to incorporate metal ions arising from orthodontic appliance corrosion into tooth enamel with resulting tooth color change.

Materials And Methods: This in vitro study used atomic absorption spectrophotometry to evaluate the presence of nickel, chromium, and iron ions in tooth enamel in three groups: a group submitted to cyclic demineralization and remineralization processes with solutions in which orthodontic appliances were previously immersed and corroded, releasing metallic ions; a control group; and another group, submitted to cycling only, without the presence of orthodontic appliances. The influence of the incorporation of these metals on a possible alteration in color was measured with a portable digital spectrophotometer using the CIE LAB system.