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Objectives: The purpose of this study was to determine differences in effectiveness between two types of mandibular advancement device (MAD)., Material and Methods: In this retrospective, cohort study, the two devices used were MAD type "Somnodent-Flex" (MAD 1) and MAD type "Herbst" (MAD 2). One hundred thirty-seven patients participated in this study, 67 patients were treated with MAD 1, and 70 patients with MAD 2. The indication MAD with obstructive sleep apnea (OSA) is based on a polysomnography test, in accordance with the CBO guidelines. The effectiveness of MAD therapy can be determined by a second polysomnography test (with the MAD in situ). The apnea-hypopnea index (AHI) is registered during the first and the second polysomnography test. Changes in these values determine the effectiveness., Results: A significant decrease in AHI was found regarding T1 and T2 for both the MADs: F (1, 134) = 140,850, p < 0,001. The mean differences of both the MADs turned out to correlate to T1. After correcting for this covariance, there was no significant difference between the two MAD devices regarding the AHI value: F (1, 134) = 1160, p = 0,283., Conclusions: The results of the present study show no significant difference in effectiveness between MAD 1 and MAD 2 in respect to the AHI value., Clinical Relevance: Since 2012, healthcare insurance companies in the Netherlands refunds MAD type "Somnodent" used for treatment of sleep apnea. It is important to investigate if this type of MAD is as more effective or less effective as other types of MADs. If research points out that other MADs are more effective in reducing the sleep apnea, refund policies have to be adapted.

The causes of bracket loss during the late phases of orthodontic treatment have hitherto been considered to be of mechanical nature (e.g. trauma, high forces applied). Recently, it was hypothesized that bacterial degradation of composite resin could be a reason for late bracket failure. This was based on the observation of apparently degraded composite on bracket bases sent to a recycling company, and on a weight loss of 0.1-1% of a limited number of composite resin foils incubated with bacteria. To further elucidate the basis for this hypothesis, we examined brackets, immediately after debonding, for signs of potential decay and tested the ability of selected bacterial species to degrade composites. Out of a total of 1056 brackets collected, 6.2% displayed signs of decay indicative of inclusion of air bubbles, corrosion of the bracket base and discoloration of the composite and comparable to the decay observed on brackets received from the recycling company. Composite discs of two different brands were each incubated with either of five strains representing different bacterial species. The incubation lasted 3 months or until the bacteria had died. There was no significant difference in weight change of the discs incubated with bacteria and control discs incubated without bacteria. Thus, our results do not support that bacterial degradation of composite resin bonding materials is a likely cause of bracket loss.