ABSTRACT
INTRODUCTION: Rotation of rounded teeth, particularly canines, is reported as one of the most difficult and inaccurate tooth movements with aligners. This retrospective study aimed to assess the accuracy and reliability of prescribed mandibular canine rotation with Invisalign aligners and the influence of attachment type and wear schedule on accuracy. METHODS: A sample of 75 subjects with mandibular canines requiring rotation was collected from an existing database. The initial, predicted finish, and achieved finish, were measured using metrology software, and the differences between predicted and achieved mandibular canine rotations were calculated. The sample was divided into 3 groups: optimized rotation attachments using 1-week wear, optimized rotation attachments using 2-week wear, and conventional rectangular attachments using 2-week wear. RESULTS: Rotation was an underexpressed movement, with an overall median sample efficiency of 75.4%. For all groups, predicted rotation was not equivalent to achieved rotation at a ± 5° equivalence margin. This indicates that none of the Invisalign SmartTrack aligner attachment configurations display clinical accuracy in their predicted rotation. By attachment type, median efficiencies of 81.5%, 76.5%, and 63.1% were found for groups 1-week wear, 2-week wear, and 2-week wear, respectively. By wear schedule, there was no significant difference in efficiency for optimized rotation attachments. CONCLUSIONS: The clinical expression of canine rotation with SmartTrack aligners is less than the prescribed rotation for all attachment configurations. Vertical rectangular attachments were associated with the least accurate expression of prescribed movement. There was no difference in rotation efficiency between 1- or 2-week aligner wear.
Subject(s)
Orthodontic Appliance Design , Orthodontic Appliances, Removable , Cuspid , Humans , Reproducibility of Results , Retrospective Studies , Tooth Movement TechniquesABSTRACT
BACKGROUND: Public awareness/knowledge on oral and pharyngeal cancer (OPC), potentially malignant disorders (PMODs) and their risk factors is crucial for prevention and early detection of OPC and PMODs. Yet, there are no published data available on the awareness and knowledge of OPC and PMODs among people living in Far North Queensland, Australia. MATERIALS AND METHODS: This study was conducted as a cross sectional survey. A self-administered questionnaire was designed and consisted of relevant questions to ascertain socio-demographic information, awareness and knowledge of OPC, PMODs and risk factors and questions on participant's exposure to risk factors and dietary history were also included. Survey was carried out at the Dental Clinic of the James Cook University School of Dentistry (JCU Dental), Cairns, Australia. Subjects above the age of 20 years (n=366) were randomly selected during the period from 31st July to 6th September 2013 and questionnaire was distributed to complete while they are waiting for treatment. Data analysis was carried out using SPSS version 21 and the chi -squared test was employed to compare groups. P<0.05 was considered statistically significant. RESULTS: The study revealed that 52.3% of the respondents were aware of the existence of OPC but only 19.0% were aware of PMODs. Of those who were aware of oral cancer, 92% agreed or strongly agreed that smoking is a strong risk factor for OPC. Similarly a relatively high proportion of the respondents agreed or strongly agreed that tobacco chewing (84%), tobacco chewing with areca nut (68%), chewing areca nut alone (51%) and exposure to actinic radiation (71%) as risk factors. However, the results for alcohol intake, age, and HPV infection were found to be relatively poor with proportions 33%, 34%, and 23% respectively. CONCLUSIONS: This study revealed an alarming lack of awareness and knowledge of OPC and PMODs.
