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Introduction: Decalcification is a significant problem during fixed orthodontic treatment. Topical Fluorides can reduce or eliminate the problem, but the relative effectiveness of different treatments or combinations of topical fluoride preparations is unknown. This systematic review was undertaken to determine the effectiveness of topical fluoride preparations in preventing decalcification during fixed orthodontic treatment. Methods: A wide search of published and unpublished material in any language was undertaken by using general and specialist databases; key dental journals were searched by hand. Predefined inclusion criteria based on objective outcome measures of decalcification, duration of treatment, presence of a comparison group, and study design were applied to determine study selection. Included studies were double extracted onto predesigned data extraction sheets. Results and conclusions: By screening titles and abstracts, we identified 143 articles; after the inclusion criteria were applied, 7 reports (of 6 studies) remained. Differences in the methodologies and reporting made statistical analysis impossible. However, the use of topical fluorides in addition to fluoride toothpaste reduced the incidence of decalcification in populations with both fluoridated and nonfluoridated water supplies. Different preparations and formats appear to decrease decalcification, but there was no evidence that any 1 method was superior. There was some evidence that the potency of fluoride preparations might be important.

The objective of this study was to evaluate the stresses generated in the bracket-cement-tooth continuum by a tensile load case when the physical and geometric properties of cement are varied. A 2-stage approach was used. In the first stage, a validated 3-dimensional finite element model of the bracket-cement-tooth system was constructed that consisted of 15,324 nodes and 2971 finite elements. Bracket base geometry was held constant; the physical properties (elastic modulus; Poisson's ratio) and geometry (lute thickness) of the cement varied. A simplified 2-dimensional model was then developed to investigate the localized effects of the cement lute thickness and the shape of the lute periphery on the stress distribution in the system. Small increases in stress were recorded under load within the cement as the rigidity of the cement increased. Similarly, Poisson's ratio values above 0.4 appeared to have a small influence on the major principal stresses in the impregnated wire mesh layer when a tensile force was applied. Variation in lute thickness was shown to have an influence on the distribution of major principal stresses within the cement lute. Increased stresses were recorded at the lute periphery as the lute dimensions increased. The morphologic features of the lute periphery also appeared to have had a significant effect on the performance of an orthodontic adhesive. Acute cementenamel angles resulted in an increased chance of singularity development and attachment failure. The physical properties and thickness of the cement lute and the shape of the cement lute periphery contribute to the stress distribution within the bracket-cement-tooth continuum and, therefore, the quality of orthodontic attachment provided. (Am J Orthod Dentofacial Orthop 2001;119:43-53)