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Materials and methods Enhance-L.C. was used with one of the manufacturer's recommended adhesives, Light-Bond, and with a second from another manufacturer, Transbond-XT. One hundred premolars were divided into four groups of 25 premolars: 1)Transbond-XT, 2) Transbond-XT/Enhance-L.C., 3) Light-Bond, 4) Light-Bond/Enhance-L.C. Main outcome measures Shear bond strength was evaluated with a universal test machine and the adhesive remaining after debonding was determined using image analysis equipment. Results Enhance-L.C. did not significantly increase the bond strength of either of the two systems (P > 0.008). However, LightBond/Enhance-L.C. provided a bond strength significantly greater (P < 0.008) than Transbond-XT and Transbond-XT/Enhance-L.C. Light-Bond also left significantly (P < 0.05) less adhesive remaining on the enamel than Transbond-XT, whether or not either of the systems were used with Enhance-L.C. Conclusions The use of Enhance-L.C with Light-Bond is to be recommended whenever extra bond strength is needed.Bracket bond failure is one of the most frustrating ocurrences in orthodontic practice. The consequences include an increase in treatment time, additional costs in both materials and personnel, and additional patient visits.

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Although the metal devices used in orthodontic treatments are manufactured highly resistance to corrosion, they may still suffer some localized corrosion resulting from the oral cavity conditions. The corrosion causes the release of metals from the alloys used for their manufacture. In this report, we evaluated the in vivo metal ions release of three alloys (stainless steel, titanium and nickel-free) usually used in the orthodontics treatments and its genotoxicity. We applied to 15 patients, between 12 and 16 years, 4 tubes and 20 brackets. Samples from oral mucosa were taken before the treatment and 30 days later. The concentration of the titanium, chromium, manganese, cobalt, nickel, molybdenum and iron were detected using inductively coupled plasma mass spectrometry (ICP-MS). The genotoxicity was measured with a comet assay (Olive moment). The oral mucosa cells in contact with the stainless steel alloy displayed the greatest titanium and manganese concentrations and those in contact with the nickel-free alloy presented the greatest concentration of chromium and iron. Both alloys, stainless steel and nickel-free, induced a higher DNA damage in the oral mucosa cells than the titanium alloy, in which the Olive moment was similar to controls. Based on the results of our study, we can conclude that titanium brackets and tubes are the most biocompatible of the three alloys.