Objective: To collect data regarding Canadian laypersons' perceptions of smile esthetics and compare these data to US data in order to evaluate cultural differences. Materials and Methods: Using Adobe Photoshop 7, a digital image of a posed smile of a sexually ambiguous lower face was prepared so that hard and soft tissue could be manipulated to alter buccal corridor (BC), gingival display (GD), occlusal cant (OC), maxillary midline to face discrepancy (MMFD), and lateral central gingival discrepancy (LCGD). Adult Canadian laypersons (n 5 103) completed an interactive computer-based survey of 29 randomized images to compare smile preferences for these variables. The custom survey was developed to display fluid, continuously appearing modifiable smile variables using MATLAB R2008 for presentation. These data were compared with previously published data for US laypersons. Statistical inference was determined using Wilcoxon rank sum tests. Results: Canadian laypersons were more sensitive in detecting deviations from ideal and had a narrower range of acceptability thresholds for BC, GD, OC, MMFD, and LCGD. Ideal esthetic values were significantly different only for BC.Conclusions: It appears that cultural differences do exist related to smile characteristics. Clinically significant differences in the preference of the smile characteristics were found between Canadian and US laypersons. Canadian laypersons, on average, were more discriminating to deviations from ideal and had a narrower range of acceptability. (Angle Orthod. 2011;81:198-205.)

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The aim of this study was to evaluate the possible effect of low intensity pulsed ultrasound (LIPUS) on tooth movement and root resorption in orthodontic patients. Twenty-one patients were included in a split-mouth study design (group 1). Ten additional patients were included with no LIPUS device being used and this group was used as the negative control group (group 2). Group 1 patients were given LIPUS devices that were randomly assigned to right or left side on upper or lower arches. LIPUS was applied to the assigned side that was obtained by randomization, using transducers that produce ultrasound with a pulse frequency of 1.5 MHz, a pulse repetition rate of 1 kHz, and average output intensity of 30 mW/cm 2 . Cone-beam computed tomography (CBCT) images were taken before and after treatment. The extraction space dimensions were measured every four weeks and root lengths of canines were measured before and after treatment. The data were analyzed using paired t-test. The study outcome showed that the mean rate of tooth movement in LIPUS side was 0.266 ± 0.092 mm/week and on the control side was 0.232 ± 0.085 mm/week and the difference was statistically significant. LIPUS increased the rate of tooth movement by an average of 29%. For orthodontic root resorption, the LIPUS side (0.0092 ± 0.022 mm/week) showed a statistically significant decrease as compared to control side (0.0223 ± 0.022 mm/week). The LIPUS application accelerated tooth movement and minimized orthodontically induced tooth root resorption at the same time.

VERIFIABLE CPD PAPER• Readers will develop an understanding of the background of nickel allergy and its epidemiology in orthodontics.• Readers will learn the signs and symptoms of a nickel allergy in orthodontics.• Readers will have an understanding of making a diagnosis and alternative methods to treat orthodontic patients who have developed an intra-oral nickel allergy due to orthodontic appliances.• Two detailed real life cases are presented. I N B R I E F PRACTICENickel is a common component in many orthodontic materials. An allergy to nickel is commonly seen in the population, more frequently in women. This allergy has increased with the more frequent use of nickel containing jewellery and in traoral piercings. As a result, this allergy can be expected to be more readily encountered in dental practice. Possible allergy to nickel should be a question in the initial patient health history questionnaire. The dental practitioner should be mindful of this allergy during the course of orthodontic treatment, and know how to diagnose a nickel allergy if it appears and subsequent action in treatment and referral if it is suspected. This paper provides a summary of nickel allergy, its epide miology, diagnosis and recommendations and alternatives to treatment. A detailed description of two cases where it was discovered in orthodontic patients is also reported.

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