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Introduction: The aim of this study was to compare the efficiency of mandibular arch alignment in 3 dimensions with a self-ligating bracket system (SmartClip, 3M Unitek, Monrovia, Calif) and a conventional preadjusted edgewise twin bracket (Victory, 3M Unitek) in nonextraction patients. This was a prospective, randomized, controlled clinical trial at the Royal London Hospital, School of Dentistry, and Kent and Canterbury Hospital, United Kingdom. Sixty-six consecutive patients satisfying the inclusion criteria were enrolled in the study. They were randomly allocated with a computer-generated system to 1 of the 2 bracket systems., Methods: Pretreatment mandibular arch irregularity was measured by using a coordinate measuring machine (Merlin II, International Metrology Systems, Gloucester, United Kingdom). A 0.016-in round martensitic active nickel-titanium aligning archwire (3M Unitek) was placed in all subjects. Mandibular arch irregularity was remeasured 8 weeks later., Results: Sixty-five subjects completed the study. Bracket type had little influence on alignment efficiency overall (P = 0.08), or in the buccal (P = 0.173) or labial segments (P = 0.528) after adjustment for pretreatment differences by analysis of covariance (ANCOVA). Alignment efficiency was highly correlated to pretreatment irregularity overall (P <0.001), both in the buccal (P = 0.001) and labial (P <0.001) segments. Increasing age appeared to have a negative effect on alleviation of irregularity, although this effect did not reach statistical significance (P = 0.053)., Conclusions: The null hypothesis that efficiency of alignment in the mandibular arch in nonextraction patients is independent of bracket type was accepted. Alignment efficiency is largely influenced by initial irregularity.

Objectives: To test the hypotheses that (1) there is no difference in the pain experience during the week following initial placement of two orthodontic appliances (SmartClip and Victory; 3M Unitek, Monrovia, Calif); and (2) there is no difference in the pain experience during removal and insertion of orthodontic archwires with these brackets., Materials and Methods: Sixty-six consecutive patients were treated with a self-ligating bracket system (SmartClip) or a conventional appliance (Victory) on the basis of computer-generated random allocation. After appliance placement and engagement of a 0.016'' nickel-titanium archwire, pain experience was recorded after 4, 24, and 72 hours and after 7 days with the use of a visual analog system (VAS) questionnaire. At a subsequent visit, participants documented pain experiences during removal and insertion of 0.019 x 0.025'' archwires on an additional 100 mm VAS questionnaire. Independent t-tests and analyses of covariance were used to analyze normally distributed data; the Mann-Whitney U-test was used for skewed distributions., Results: Forty-eight (72.2%) and fifty-one (77.3%) subjects completed the first and second parts of the study, respectively. Bracket type had no influence on pain experience at 4 hours (P = .958), 24 hours (P = .289), 72 hours (P = .569), and 7 days (P = .756) following appliance placement. However, bracket type significantly influenced pain experience during archwire removal (P = .001) and insertion (P = .013)., Conclusions: Hypothesis 1 cannot be rejected. The bracket type had no effect on subjective pain experience during the first week after initial placement of two preadjusted orthodontic appliances. Hypothesis 2 was rejected. Significantly greater discomfort was experienced during archwire insertion and removal with the SmartClip appliance.

A gamma-ray source with an intense component around the giant dipole resonance for photonuclear absorption has been obtained via bremsstrahlung of electron bunches driven by a 10-TW tabletop laser. 3D particle-in-cell simulation proves the achievement of a nonlinear regime leading to efficient acceleration of several sequential electron bunches per each laser pulse. The rate of the gamma-ray yield in the giant dipole resonance region (8