Orthodontics

The present review was undertaken to investigate the orofacial muscle response to various types of orthodontic treatment and consider any possible neuromuscular adaptation to the therapeutic result. The methods of evaluating orofacial function are briefly discussed, and various muscular adaptive responses are described according to methods of treatment. From the contradicting evidence in the literature it can be inferred that no definite conclusions can be reached on muscle functional therapeutic alterations. Many factors hamper a more systematic approach to this subject. Studies available present different methodological approaches in assessing possible adaptation, and use various appliances, making scientific comparisons of the outcome difficult. Furthermore, muscle function has not been assessed longitudinally to determine any long-term effects, nor are the results compared to mean measurements from untreated populations. Therefore, the need for meticulous research is underlined,...

The purpose of this study was to investigate the composition of as-received, retrieved, and recycled stainless steel brackets. New, used, and recycled brand-matched, slot size-matched, and prescription-matched appliances were subjected to scanning electron microscopy and energy dispersive electron probe microanalysis. Elemental analysis was performed on randomly selected surface bracket base and wing areas, and metal content was statistically analyzed with the 2-way ANOVA and the Tukey test, with treatment (as-received, retrieved, and recycled) and bracket regions (base and wing) serving as discriminating variables (␣ ϭ 0.05). The results showed that there was no difference in the surface composition of the base; however, surface area-wing analysis indicated that nickel content was decreased in retrieved and recycled specimens, implying that an ionic release effect occurred in vivo. Differences were noted between bracket base and wing with respect to elemental composition for the same brackets, implying that the base and wings are manufactured from different alloys. (Am J Orthod Dentofacial Orthop 2002;122:217-20)

Introduction: The aim of this study was to assess the effect of intraoral aging on the setting status of a resin composite and a glass ionomer adhesive, relative to control specimens stored in water. Methods: Metallic brackets were bonded with resin composite orthodontic adhesive (Transbond XT; 3M Unitek, Monrovia, Calif) or a glass ionomer cement (Fuji I; GC, Tokyo, Japan) to recently extracted premolars and kept in water for 6 months. The same materials were also bonded to the premolars of orthodontic patients. After 6 months, the teeth were carefully extracted, with the brackets intact on their buccal surfaces. All teeth were embedded in epoxy resin and sectioned buccolingually. Fourier transform infrared microscopy and Raman microscopy were used for the estimation of the degree of cure in the composite and the salt yield in the glass ionomer adhesives. Results: The control samples of the composite showed significantly lower degrees of cure than did the retrieved specimens (52.40% 6 3.21% vs 57.62% 6 1.32% by Fourier transform infrared microscopy, and 61.40% 6 2.61% vs 67.40% 6 3.44% by Raman microscopy). Raman microscopy significantly overestimated the degree of cure and failed to provide reliable information for the salt yield in the glass ionomer cement. Fourier transform infrared microscopy showed increased, but no statistically significant difference in, aluminum-carboxylate salts in the retrieved specimens. Conclusions: Enhanced oxidation of residual carbon-carbon bonds in the composite and slightly increased dissolution of the weaker calcium-salt phase in the glass ionomer cement were the main differences in the intraorally aged specimens in comparison with the specimens stored in water. (Am J Orthod Dentofacial Orthop 2014;145:425-33)

Objective: To comparatively assess clinical failure rate of brackets cured with two different photopolymerization sources after nine months of orthodontic treatment. Materials and Methods: The sample of this study comprised 30 patients who received comprehensive orthodontic treatment by means of fixed appliances. Using the same adhesive, 600 stainless steel brackets were directly bonded and light cured for 10 seconds with the light-emitting diode (LED) lamp or for 20 seconds with the conventional halogen lamp. A split-mouth design randomly alternated from patient to patient was applied. Failure rates were recorded for nine months and analyzed with Pearson 2 test, and log-rank test at ␣ ϭ .05 level of significance. Results: The overall failure rate recorded with the halogen unit (3.33%) was not significantly different from the failure rate for the LED lamp (5.00%). Significantly more failures were found in boys compared with girls, in the mandibular dental arch compared with the maxillary arch, and in posterior segments compared with anterior segments. However, no significant difference was found between the right and left segments. Conclusion: Both light-curing units showed sufficiently low bond failure rates. LED curing units are an advantageous alternative to conventional halogen sources in orthodontics because they enable a reduced chair-time bonding procedure without significantly affecting bond failure rate.