No abstract

Objectives: To investigate the effects of long-term, artificially created, hypofunctional occlusion and its recovery on the morphology of rat molar roots. Material and Methods: Eighteen 5-week-old Wistar-strain male rats were randomly divided according to their periodontal conditions into normal, hypofunctional, and recovery groups (n 5 6 in each). In the experimental hypofunctional and recovery groups, a bite-raising appliance was set to produce hypofunction at the molar region. All groups were analyzed at 16 weeks of age using three-dimensional micro-computed tomography. Root length, width, and area as well as the thickness and the area of the periodontal ligament (PDL) space of the maxillary first molar were calculated. Results: Roots were longer and narrower in the hypofunctional group than in the control group. The mesial root in particular showed a dramatic change. Root area also decreased significantly in the hypofunctional group compared to the other groups. Moreover, the PDL thickness and area decreased significantly in the hypofunctional group compared to the control group, but increased in the recovery group compared to the hypofunctional group. Conclusions: These findings suggest that root size and PDL structure may be reduced due to disuse atrophy resulting from a defect in occlusal function, but may be recovered following a gain of occlusal stimuli. (Angle Orthod. 2013;83:597-604.)

In a 4-week orthodontic adjustment period, intermittent force significantly reduced the amount of root resorption compared with continuous force. Although there was less degree of tooth movement with intermittent force, unwanted rotational movement was avoided. This is crucial in patients who are predisposed to orthodontically induced inflammatory root resorption, and the use of this intermittent regimen should be considered.

Objective: The present study aimed to determine how the popularity of ‘Do It Yourself’ (DIY) aligner videos available on YouTube relates to authorship, video content, quality and reliability, and to determine why DIY aligners appeal to consumers. Methods: The Google Trends website was interrogated to identify the most frequently used search terms regarding DIY aligners which were subsequently applied to a search of the YouTube website. One hundred twenty-three videos were assessed for completeness of content, reliability (using a modified version of the DISCERN tool) and quality using the Global Quality Score (GQS). The relationship between the variables and authorship, popularity, financial interest, and recommendations were assessed using Pearson Correlation Coefficients. Results: Laypeople produced the majority of the videos (73%). Dentists/Orthodontists uploaded only 4% of the videos, and dental professional bodies uploaded none. Most videos (86%) were content poor, unreliable (average DISCERN score of 1) and of low quality (average GQS of 2). The more popular, reliable and superior the quality of the video, the greater the number of views, likes and viewing rate (p < 0.05). Conversely, authors with a financial interest and lower quality and less reliable videos were more likely to recommend DIY aligners. Consumers sought DIY aligner treatment due to a reduced cost. Conclusions: YouTube should not be considered as a viable nor reliable source of DIY aligner information for patients or the public. Dentists/Orthodontists should be encouraged to publish comprehensive and more informative YouTube content related to DIY aligners.