Objectives: The fitting of aligners on anchorage teeth is a crucial factor in clear aligner orthodontics. The purpose of this experimental study was to evaluate the fitting of two aligner systems, Invisalign and CA-Clear Aligner, using scanning electron microscopy (SEM). Materials and Methods: Passive aligners (Invisalign and CA-Clear Aligner) were adapted on resin casts obtained by stereolithography (STL) files of a patient, and then sectioned buccolingually. Upper and lower central incisors, upper and lower first premolars, and upper and lower first molars were the regions analyzed. Representative microphotographs of sections were taken with a scanning electron microscope (SEM); a total of 160 micrometric measurements were obtained and analyzed with ANOVA tests. Results: Invisalign provided an overall better fit on lower incisors ( F = 11.48, P = .0095) and on lower molars ( F = 19.93, P = .0012). Considering the different regions, Invisalign provided better fit at the gingival edge of the buccal aspect on lower incisors ( F = 11.33, P = 0.0056) and at the gingival edge of the lingual aspect on upper premolars ( F =5.34, P = 0.0047). On the upper molars, Invisalign provided better fit at the gingival edge of the buccal aspect, while CA-Clear Aligner provided better fit at the buccal maximum convexity, on the buccal cusp, on the occlusal groove and at the palatal cusp. On lower molars, Invisalign showed a more accurate fit at the buccal aspect points. Conclusions: Invisalign and CA-Clear Aligner exhibited comparable fit on anchorage teeth. Invisalign provided better fit at the gingival edges of aligners, while the CA-Clear Aligner provided better fit on complex occlusal surfaces.

Objectives: To measure the thickness homogeneity of Invisalign (Align Technology Inc, San José, Calif) aligners with micro-computed tomography (micro-CT) scans. Materials and Methods: Starting from micro-CT scanning of 20 different aligners, multiplanar reconstructions were obtained. An orthodontist blinded about the study measured aligner thickness in different regions (molar, canine, incisor) and in different sites (gingival–buccal, buccal, occlusal, lingual, and gingival–lingual). To assess various thicknesses in different aligner sites and regions, the sample was stratified into subgroups and linear regression analysis was performed. Results: Descriptive analysis showed that mean thickness of aligners in the incisor region ranged from 0.582 mm to 0.639 mm, in the canine region from 0.569 mm to 0.644 mm, and in the molar region from 0.566 mm to 0.634 mm. Student's t -tests showed no significant differences in the aligner thickness of different regions when data were stratified by different sites. Student's t -tests showed significant differences in thickness homogeneity for the molar region when the data were stratified by tooth (mean difference = 0.068 mm; 95% confidence interval, 0.009–0.126 mm; P = .024). Conclusions: Invisalign aligner thickness is characterized by small differences. The only significant difference was revealed in the molar region where thickness of the gingival–lingual edge is significantly thinner than that measured at the occlusal aspect. From a clinical perspective, the results of the present study could be considered to explain the reduced predictability of several orthodontic tooth movements in the molar region.

Pathologic tooth migration (PTM) is a complication of Stage III and IV periodontitis. This pilot study aims to analyze the periodontal response to orthodontic aligner therapy in stage IV periodontitis patients, by perio charting and digital orthodontic data obtained from intraoral scans. Following periodontal treatment of 21 recruited patients, 11 underwent clear aligner treatment. Periodontal data (Probing Pocket Depth—PPD, Recession Index—REC, Clinical Attachment Loss—CAL) were collected at baseline (T0), after periodontal treatment (T1), and at the end of the orthodontic treatment (T2). Digital data obtained at T1 and T2 were processed with the 3D software Geomagic^® Control X™. Occlusograms obtained by the proximity sensors of the scans were converted into differently colored pixelated areas. These results were compared to highlight changes in clinical crown length or occlusal contact areas. The results showed a slight increase in the REC index and a statistically significant reduction of PPD and CAL at T1 and T2. Digital data showed a statistically significant decrease in terms of gingival recessions and clinical crowns at the end of orthodontic treatment. Hard occlusal contacts showed a statistically significant decrease by the end of the orthodontic treatment. The results are comparable to those reported in the scientific literature for fixed orthodontic treatment. Clear aligner treatment could be considered an option in patients with severe periodontitis, promoting final light occlusal contacts.