Forces and moments generated by aligner‐type appliances for orthodontic tooth movement: A systematic review and meta‐analysis

The aim of this review was to systematically appraise the evidence on aligner mechanics and forces and moments generated across difference types of aligners. In vitro- laboratory studies for model simulated tooth movement with aligners. Database searches within Medline via Pubmed, Cochrane Central Register of Controlled Trials (CENTRAL), LILACS via BIREME Virtual Health Library. Unpublished literature was also searched in Open Grey, ClinicalTrials.gov (www.clinicaltrials.gov), the National Research Register (www.controlled-trials.com) and Center for Open Science (Open Science Framework), using the terms "aligner" AND "orthodontic". Risk of bias assessment was based on the Cochrane Risk of Bias tool. Random effects meta-analyses were conducted. A total of 447 studies were identified through electronic search and after careful consideration of pre- defined eligibility criteria, 13 deemed eligible for inclusion, while 2 were included in the quantitative synthesis. When palatal tipping of the upper central incisor through PET-G aligners was considered, aligner thickness of 0.5, 0.625 or 0.75 mm was not associated with a significantly different moment to force (M/F) ratio, given a common gingival edge width of 3-4 mm. Aligner thickness does not appear to possess a significant role in forces and moments generated by clear aligners under specific settings, while the most commonly examined tooth movements are tipping and rotation. The findings of this review may be applicable to certain conditions in laboratory settings. Keywords: aligner; force; meta-analysis; moment; systematic review; tooth movement

Sources of Authority for Leadership and Instructional Technology Coaches\u27 Diffusion of High Access Teaching and Learning

This study used a theoretical framework to explore the leadership of three schoolbased instructional technology coaches (ITCs). The researcher employed typical qualitative fieldwork methods by compiling observation notes, interview transcripts, and archival documents for data analysis. This research and dissertation were also placed in context with the tenets of diffusion research. The collected evidence was analyzed with a theory that proposes five sources of authority for leadership: bureaucratic, psychological, technical rational, professional, and moral. The study presents four major findings: First, ITCs do not use bureaucratic or moral sources of authority for leadership. Second, the coaches are aware of and use technical rational and professional sources of authority. Third, the participants may use some of the characteristics of psychological sources of authority for leadership. Finally, this study verifies that all five theoretical sources of authority are discernible in the participants\u27 school district. The author recommends that educators combine their respective sources of authority in diffusion of innovation. Schools should recognize and use in combination their administrators’ bureaucratic, coaches’ technical rational, and teachers’ professional sources of authority for leadership. This study suggests future research in applying the theoretical framework: for tests of the consequences of each source of authority for leadership; to the use of diffusion; for leadership in the diffusion of professional learning communities; to analyze the 2014 Interstate School Leaders Licensure Consortium (ISLLC) standards for school leaders

Image analysis and superimposition of 3-dimensional cone-beam computed tomography models

Three-dimensional (3D) imaging techniques can provide valuable information to clinicians and researchers. But as we move from traditional 2-dimensional (2D) cephalometric analysis to new 3D techniques, it is often necessary to compare 2D with 3D data. Cone-beam computed tomography (CBCT) provides simulation tools that can help bridge the gap between image types. CBCT acquisitions can be made to simulate panoramic, lateral, and posteroanterior cephalometric radioagraphs so that they can be compared with preexisting cephalometric databases. Applications of 3D imaging in orthodontics include initial diagnosis and superimpositions for assessing growth, treatment changes, and stability. Three-dimensional CBCT images show dental root inclination and torque, impacted and supernumerary tooth positions, thickness and morphology of bone at sites of mini-implants for anchorage, and osteotomy sites in surgical planning. Findings such as resorption, hyperplasic growth, displacement, shape anomalies of mandibular condyles, and morphological differences between the right and left sides emphasize the diagnostic value of computed tomography acquisitions. Furthermore, relationships of soft tissues and the airway can be assessed in 3 dimensions

Unilateral segmental odontomaxillary hypoplasia: an unusual case report

Facial asymmetry is not an uncommon occurrence in day to day dental practice. It can be caused by various etiologic factors ranging from facial trauma to serious hereditary conditions. Here, we report a rare case of non-syndromic facial asymmetry in a young female, who was born with this condition but was not aware of the progression of asymmetry. No relevant family history was recognized. She was also deficient in both deciduous and permanent teeth in the corresponding region of maxilla. Hence, the cause of this asymmetry was believed to be a segmental odontomaxillary hypoplasia of left maxilla accompanied by agenesis of left maxillary premolars and molars and disuse atrophy of corresponding facial musculature. This report briefly discussed the comparative features of segmental odontomaxillary hypoplasia, hemimaxillofacial dysplasia, and segmental odontomaxillary dysplasia and justified the differences between segmental odontomaxillary hypoplasia and the other two conditions

Effects of Vertical Movement of the Anterior Nasal Spine on the Maxillary Stability After LeFort I Osteotomy for Pitch Correction

Few reports have so far evaluated the maxillary stability after LeFort I osteotomy (L-1) for pitch correction. In the current study, the authors assessed the SN-PP (palatal plane) to evaluate the skeletal stability after osteotomy with clockwise or counter-clockwise rotation and investigated the effects of anterior nasal spine (ANS) and posterior nasal spine (PNS) movement on the stability of the SN-PP. The SN-PP and the positions of ANS, PNS, and point A were measured on lateral cephalograms before surgery (T1), immediately after surgery (T2), and more than 1 year after surgery (T3). All measured angle and points were stable in 4 cases of counterclockwise rotation. In the 16 cases of clockwise rotation, T3-T2 of SN-PP, ANS, and point A was ?2.058 ?2.56 mm, and ?1.64 mm, when the SN-PP increased more than 48 after osteotomy. When the ANS moved downward more than 3 mm, the ANS and point A relapsed significantly by 2.75 and 2.31 mm, while the SN-PP relapsed 1.618 more than 1 year after surgery. When the SN-PP increased by more than 48 or the ANS moved downward by more than 3 mm, the authors suggest shifting the PNS upward instead of moving the ANS downward

The hierarchy of stability and predictability in orthognathic surgery with rigid fixation: an update and extension

A hierarchy of stability exists among the types of surgical movements that are possible with orthognathic surgery. This report updates the hierarchy, focusing on comparison of the stability of procedures when rigid fixation is used. Two procedures not previously placed in the hierarchy now are included: correction of asymmetry is stable with rigid fixation and repositioning of the chin also is very stable. During the first post-surgical year, surgical movements in patients treated for Class II/long face problems tend to be more stable than those treated for Class III problems. Clinically relevant changes (more than 2 mm) occur in a surprisingly large percentage of orthognathic surgery patients from one to five years post-treatment, after surgical healing is complete. During the first post-surgical year, patients treated for Class II/long face problems are more stable than those treated for Class III problems; from one to five years post-treatment, some patients in both groups experience skeletal change, but the Class III patients then are more stable than the Class II/long face patients. Fewer patients exhibit long-term changes in the dental occlusion than skeletal changes, because the dentition usually adapts to the skeletal change