Objective: To analyse through a systematic review the effectiveness of clear aligners by assessing: (a) predictability of clear aligners and (b) treatment outcome comparison of clear aligner therapy with fixed appliance therapy.Methods: An electronic search was made from January 2014 to April 2019 using MEDLINE, Embase, Web of Science and LILACS databases without any limitations on language. Three reviewers independently assessed the articles. Quality assessment of observational studies and randomized control trial was done by using the ROBINS tool and Cochrane risk of bias tool, respectively. GRADE instrument was used to assess certainty level for each identified outcome.Results: Seven eligible articles (one randomized controlled trial and six retrospective cohort) were included in our systematic review. Most of the studies (six out of seven) had a moderate risk of bias and one had a high risk of bias.Conclusions: ‘Low to moderate level’ of certainty in regard to specific clear aligner therapy tooth movements’ efficiency was identified. Clear aligners may produce clinically acceptable outcomes that could be comparable to fixed appliance therapy for buccolingual inclination of upper and lower incisors in mild to moderate malocclusions. However, not all potential clinical scenarios have been assessed in the included studies. Most of the tooth movements may not be predictable enough to be accomplished with only one set of trays with clear aligners despite the recent advances in technology.

Objective: To compare the aesthetic perception of different anterior visible occlusions in different facial and dental views (frontal view, lower facial third view and dental view) by lay persons. Design: Cross-sectional survey, Lima, Perú, 2002. Subjects: The different views were rated by 91 randomly selected adult lay persons. Main outcome measurement: Visual Analogue Scale (VAS) ratings of aesthetic perception of the views. Results: Anterior visible occlusion, photographed subject and view (p<0.001) had a significant effect on the aesthetic ratings. Also gender (p=0.001) and the interaction between gender and level of education (p=0.046) had a significant effect over the aesthetic rating. Conclusions: A lay panel perceived that the aesthetic impact of the visible anterior occlusion was greater in a dental view compared with a full facial view. The anterior visible occlusion, photographed subject, view type are factors, which influence the aesthetic perception of smiles. In addition, gender and level of education had an influence.

The development of 3D technology and the trend of increasing the use of intraoral scanners in dental office routine lead to the need for comparisons with conventional techniques. To determine if intra- and inter-arch measurements from digital dental models acquired by an intraoral scanner are as reliable and valid as the similar measurements achieved from dental models obtained through conventional intraoral impressions.Search methods: An unrestricted electronic search of seven databases until February 2015. Studies that focused on the accuracy and reliability of images obtained from intraoral scanners compared to images obtained from conventional impressions.Data collection and analysis: After study selection the QUADAS risk of bias assessment tool for diagnostic studies was used to assess the risk of bias (RoB) among the included studies. Four articles were included in the qualitative synthesis. The scanners evaluated were OrthoProof, Lava, iOC intraoral, Lava COS, iTero and D250. These studies evaluated the reliability of tooth widths, Bolton ratio measurements, and image superimposition. Two studies were classified as having low RoB; one had moderate RoB and the remaining one had high RoB. Only one study evaluated the time required to complete clinical procedures and patient’s opinion about the procedure. Patients reported feeling more comfortable with the conventional dental impression method. Associated costs were not considered in any of the included study. Inter- and intra-arch measurements from digital models produced from intraoral scans appeared to be reliable and accurate in comparison to those from conventional impressions. This assessment only applies to the intraoral scanners models considered in the finally included studies. Digital models produced by intraoral scan eliminate the need of impressions materials; however, currently, longer time is needed to take the digital images. PROSPERO (CRD42014009702). None.