Orthodontic treatment aims at providing an acceptable functional and aesthetic occlusion with appropriate tooth movements. These movements are strongly related to interactions of teeth with their supportive periodontal tissues. In recent years, because of the increased number of adult patients seeking orthodontic treatment, orthodontists frequently face patients with periodontal problems. Aesthetic considerations, like uneven gingival margins or functional problems resulting from inflammatory periodontal diseases should be considered in orthodontic treatment planning. Furthermore, in cases with severe periodontitis, orthodontics may improve the possibilities of saving and restoring a deteriorated dentition. In modern clinical practice, the contribution of the orthodontist, the periodontist and the general dentist is essential for optimized treatment outcomes. The purpose of this systematic review is to highlight the relationship between orthodontics and periodontics in clinical practice and to improve the level of cooperation between dental practitioners. Potentials and limitations that derive from the interdisciplinary approach of complex orthodontic-periodontal clinical problems are discussed.

BackgroundAim was to systematically search the literature and assess the available evidence regarding the clinical effectiveness of the Invisalign® system.MethodsElectronic database searches of published and unpublished literature were performed. The reference lists of all eligible articles were examined for additional studies. Reporting of this review was based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.ResultsThree RCTs, 8 prospective, and 11 retrospective studies were included. In general, the level of evidence was moderate and the risk of bias ranged from low to high, given the low risk of bias in included RCTs and the moderate (n = 13) or high (n = 6) risk of the other studies. The lack of standardized protocols and the high amount of clinical and methodological heterogeneity across the studies precluded a valid interpretation of the actual results through pooled estimates. However, there was substantial consistency among studies that the Invisalign® system is a viable alternative to conventional orthodontic therapy in the correction of mild to moderate malocclusions in non-growing patients that do not require extraction. Moreover, Invisalign® aligners can predictably level, tip, and derotate teeth (except for cuspids and premolars). On the other hand, limited efficacy was identified in arch expansion through bodily tooth movement, extraction space closure, corrections of occlusal contacts, and larger antero-posterior and vertical discrepancies.ConclusionsAlthough this review included a considerable number of studies, no clear clinical recommendations can be made, based on solid scientific evidence, apart from non-extraction treatment of mild to moderate malocclusions in non-growing patients. Results should be interpreted with caution due to the high heterogeneity.Electronic supplementary materialThe online version of this article (10.1186/s40510-018-0235-z) contains supplementary material, which is available to authorized users.

Serial 3-dimensional dental model superimposition provides a risk-free, detailed evaluation of morphological alterations on a patient’s mouth. Here, we evaluated accuracy and precision of five palatal areas, used for superimposition of maxillary 3D digital dental casts. Sixteen pre- and post-orthodontic treatment dental casts of growing patients (median time lapse: 15.1 months) were superimposed on each palatal area using the iterative closest point algorithm. Area A (medial 2/3 of the third rugae and a small area dorsal to them) was considered the gold standard, due to high anatomical stability. Areas B, C, and D added a distal extension along the midpalatal raphe, an anterior extension to the second rugae, and the remaining palatal surface, respectively. Area E was similar to A, located more posteriorly. Non parametric multivariate models showed minimal or no effect on accuracy and precision by operator, time point, or software settings. However, the choice of superimposition area resulted in statistically significant differences in accuracy and clinically significant differences in detected tooth movement (95% limits of agreement exceeding 1 mm and 3°). Superimposition on area A provided accurate, reproducible, and precise results. Outcomes were comparable for area B, but deteriorated when alternative areas were used.

intraoral three-dimensional imaging has gained great interest in dentistry as a mean to generate risk-free imprints of the oral cavity. Accurate intraoral models facilitate proper diagnosis, growth assessment, outcome evaluation, and 3D printing applications. Here, in an actual clinical setup on 12 subjects, we evaluate the trueness and precision of two widely used intraoral scanners (TRIOS 3, 3Shape and CS 3600, Carestream), using an industrial scanner (Artec Space Spider) as a reference. Surface based matching was implemented using the iterative closest point algorithm (ICP). Trueness of the intraoral scans was analyzed by measuring their distance from the reference scan, in the upper buccal front area. precision was tested through the distance of repeated scans regarding the whole dental arch, following superimpositions in the buccal front and in the whole dental arch area. TRIOS 3 displayed slightly higher precision (approximately 10 μm) compared to CS 3600, only after superimposition on the whole dental arch (p < 0.05). Both intraoral scanners showed good performance and comparable trueness (median: 0.0154 mm; p> 0.05). However, in individual cases and in various, not spatially defined areas, higher imprecision was evident. thus, the intraoral scanners' appropriateness for highly demanding, spatially extended clinical applications remains questionable.Digital three-dimensional imaging has gained great interest in dentistry as a mean to generate an imprint of the oral cavity. Digital dental models can overcome certain drawbacks associated with plaster models, such as patient discomfort and vulnerability. Being also advantageous in terms of cost, time, and space required, digital models will probably soon become the new standard in clinical practice 1 .Currently there are two ways to generate a digital 3D model: direct intraoral digital impression with an intraoral scanner and extraoral scanning of conventional plaster casts or impressions. In contemporary clinical practice, alginate impressions are still commonly used due to simplicity reasons, adequate accuracy for diagnosis and low costs. However, the intraoral scans are very rapidly incorporated in everyday practice.Several studies have tested the performance of intraoral scanners both in vivo and in vitro and concluded that relatively precise 3D dental model representations of a patient's mouth can be performed 2-4 . The accuracy of intraoral digital scans has also been reported to be clinically adequate as assessed through 2D linear measurements 5,6 or 3D surface assessments 6-8 . Thus, the models obtained through intraoral scans are satisfactory for diagnostic reasons.However, direct intraoral scans have been shown to have a degree of imprecision and inaccuracy, attributed to the 3D model generation process 3,7,9 . So far, there are few in vivo studies that evaluated complete-arch scans acquired directly in the patient's mouth. To our knowledge, there is only one study which tested the accuracy of full arch digital impression procedure in a clinical set...

ObjectivesTo test the applicability, accuracy, precision, and reproducibility of various 3D superimposition techniques for radiographic data, transformed to triangulated surface data.MethodsFive superimposition techniques (3P: three-point registration; AC: anterior cranial base; AC + F: anterior cranial base + foramen magnum; BZ: both zygomatic arches; 1Z: one zygomatic arch) were tested using eight pairs of pre-existing CT data (pre- and post-treatment). These were obtained from non-growing orthodontic patients treated with rapid maxillary expansion. All datasets were superimposed by three operators independently, who repeated the whole procedure one month later. Accuracy was assessed by the distance (D) between superimposed datasets on three form-stable anatomical areas, located on the anterior cranial base and the foramen magnum. Precision and reproducibility were assessed using the distances between models at four specific landmarks. Non parametric multivariate models and Bland-Altman difference plots were used for analyses.ResultsThere was no difference among operators or between time points on the accuracy of each superimposition technique (p>0.05). The AC + F technique was the most accurate (D<0.17 mm), as expected, followed by AC and BZ superimpositions that presented similar level of accuracy (D<0.5 mm). 3P and 1Z were the least accurate superimpositions (0.790.05), the detected structural changes differed significantly between different techniques (p<0.05). Bland-Altman difference plots showed that BZ superimposition was comparable to AC, though it presented slightly higher random error.ConclusionsSuperimposition of 3D datasets using surface models created from voxel data can provide accurate, precise, and reproducible results, offering also high efficiency and increased post-processing capabilities. In the present study population, the BZ superimposition was comparable to AC, with the added advantage of being applicable to scans with a smaller field of view.