The Angle orthodontist最新文献

Objectives: To compare the buccal and palatal bone changes of maxillary posterior teeth produced by hybrid hyrax (HH) and conventional hyrax (CH) expanders in growing patients.

Material and methods: A sample of 32 patients with posterior crossbites in the late mixed dentition was recruited and randomly allocated into two groups. Group HH was composed of 18 individuals with a mean age of 10.7 years (six female, 12 male) treated with a hybrid expander with two anterior parasagittal miniscrews. Group CH was composed of 14 individuals with a mean age of 11.4 years (six female, eight male) treated with a conventional Hyrax expander. Cone-beam computed tomography (CBCT) exams were obtained before expansion (T1) and after 11 months when the expander was removed (T2). Buccal and palatal bone plate thickness and height of maxillary posterior teeth were measured. Intergroup comparisons were performed using t or Mann-Whitney tests (P < .05).

Results: The CH group showed greater decreases of the buccal bone plate height (mean change: 1.27 mm) at the maxillary first premolars compared to the HH group (mean change: 0.11 mm, P = .001). No intergroup difference was found for changes in the buccal and palatal bone thickness.

Conclusions: Hybrid expanders showed a tendency to cause less negative impact on the buccal bone plate height of first premolars compared to conventional Hyrax expanders. However, the difference was not clinically significant. Both hybrid and conventional Hyrax expanders are safe for the alveolar bone morphology in the late mixed dentition.

Objectives: To compare changes in upper arch dimension and molar inclination between Invisalign First (IF) and removable acrylic expander (RE) treatments during the mixed dentition period.

Materials and methods: Seventeen patients meeting inclusion criteria underwent IF treatment and were age matched with a group that received treatment with a removable acrylic expander (RE). Intercanine width (ICW), intermolar width, arch depth, buccolingual inclination of the first molars (MI), surface area (SA) and volume (VAP) of the anterior palate, and expansion were compared before and after treatment. The predictability of expansion was calculated for the IF group. Analysis of variance and Kruskal-Wallis tests were used to assess differences.

Results: The ICW increased significantly by 2.14 mm in the IF group and 3.49 mm in the RE group, with no significant intergroup difference. Both groups exhibited significant increases in intermolar width (P < .05), except for intermolar distopalatal width in the IF group (P = .246). Mesiobuccal rotation of the first molar was observed with IF treatment. Although SA and VAP increased in both groups, the changes were not significant for the IF group (P > .05). The RE group exhibited significantly higher increases (P < .05), with an SA increase of 34.32 mm2 and VAP increase of 119.15 mm3. MI changes were in the opposite directions. The prediction accuracy of expansion was 70.28% for canines and 34.12% for first molars.

Conclusions: Both appliances effectively expanded the intercanine region in growing patients. Expansion predictability was lower in first molars than in canines for the IF group. Removable acrylic expanders could be a choice of preference for expansion targeted to the molar region.

Objectives: To evaluate the effects of bone-anchored maxillary protraction (BAMP) treatment and longterm stability in growing cleft lip and palate and isolated cleft palate (CLP/CP) patients with mild maxillary hypoplasia and to compare maxillary growth patterns of BAMP-treated patients to matched control CLP/CP patients.

Materials and methods: Ten patients with CLP/CP were treated with BAMP; they were compared to the maxillary growth pattern of 10 age-matched cleft control patients with no maxillary protraction treatment, who later received surgical Le Fort I maxillary advancement after the growth period. The assessment of maxillary growth and the occlusion started at mean 8 years of age and continued until mean 18 years of age.

Results: The use of BAMP orthopedic traction changed the growth pattern of mild hypoplastic maxilla toward a more anterior direction and advanced the face even above the level of Le Fort lll with only a minor effect on dentoalveolar units. The correction of occlusion and facial convexity were stable in the long term.

Conclusions: The using BAMP may improve the position of the maxilla relative to the anterior cranial base for the correction of mild maxillary hypoplasia in adolescent patients with CLP/CP. The achieved results are rather stable in the long term.

Objectives: To identify whether intramaxillary miniscrew anchorage could achieve a better maxillary arch distalization effect in clear aligner treatment compared to Class II elastics.

Materials and methods: Thirty adult patients with Class II dentition who were treated with whole maxillary arch distalization using clear aligners were collected. Either intramaxillary miniscrew anchorage (miniscrew group, n = 17) or intermaxillary Class II elastics (Class II elastic group, n = 13) were used to support maxillary arch distalization. Three-dimensional predicted and achieved displacements, and angular changes of maxillary posterior teeth and anterior teeth, were measured and compared.

Results: The achieved distalization efficiency was 36.2%-43.9% in the posterior teeth and the retraction efficiency was 36.9%-49.4% in the anterior teeth. No statistically significant differences were found in maxillary arch distalization efficiency between the groups. The miniscrew group achieved less incisor extrusion and posterior tooth distal tipping than the Class II elastic group. Both groups achieved comparable arch expansion, posterior tooth buccal inclination, and anterior tooth lingual inclination.

Conclusions: Intramaxillary miniscrew anchorage and intermaxillary Class II elastics achieved comparable efficiency in maxillary arch distalization. However, the miniscrew anchorage showed better vertical control in anterior teeth and mesiodistal tipping control in posterior teeth.

Objectives: To determine the impact of build orientation, increased layer thickness, and dental crowding on the trueness of three-dimensional (3D)-printed models, and to evaluate how these parameters affect the fit of thermoformed appliances.

Materials and methods: Ninety-six dental models were printed horizontally and vertically on the building platform using different 3D-printing technologies: (1) a stereolithography (SLA) printer with layer thicknesses of 160 μm and 300 μm and (2) a digital light processing (DLP) printer with layer thicknesses of 100 μm and 200 μm. Each printed model was digitalized and superimposed on the corresponding source file using 3D rendering software, and deviations were quantified by the root mean square values. Subsequently, a total of 32 thermoformed appliances were fabricated on top of the most accurate 3D-printed models, and their fit was evaluated by digital superimposition and inspection by three blinded orthodontists. Paired t-tests were used to analyze the data.

Results: Significant differences (P < .05) between printing technologies used were identified for models printed horizontally, with the SLA system achieving better trueness, especially in crowded dentitions. No significant differences between technology were found when models were printed vertically. The highest values of deviation were recorded in appliances fabricated on top of DLP-printed models. The results of the qualitative evaluation indicated that appliances fabricated on top of SLA models outperformed the DLP-modeled appliances.

Conclusions: Three-dimensional printing with increased layer height seems to produce accurate working models for orthodontic applications.

A bone-borne full-arch vertical control strategy using miniscrews was deployed with aligners to treat a case of skeletal hyperdivergent Class II malocclusion with bimaxillary protrusion. Miniscrews were inserted in the posterior buccal and palatal regions and the anterior buccal region of the maxilla to distribute vertical intrusive force through the upper arch by anchoring vertical elastics from the miniscrews to the aligners. Synergetic lower anterior intrusion was completed using bilateral posterior miniscrews to counteract the extrusive force generated. Substantial full upper arch and lower anterior vertical intrusion was achieved. In conjunction with en masse anterior-posterior retraction, synergetic posterior and anterior vertical intrusion facilitated counterclockwise rotation of the mandible, creating significant esthetic improvement. Anterior vertical elastics also provided flaring of the anterior teeth, reducing the side effect of lingual tipping from en masse retraction, while successfully controlling overbite and incisor torque during space closure. The bone-borne full-arch vertical intrusion strategy can work well with aligners to address hyperdivergent skeletal Class II malocclusion with bimaxillary protrusion.

Objectives: To compare orthodontic treatment (OT) outcome in adolescents undergoing nonextraction fixed OT with or without bonding of second molars using the score of the American Board of Orthodontics Cast Radiograph Evaluation (C-R-Eval).

Materials and methods: This study included healthy adolescents with skeletal Class I or mild Class II/Class III malocclusion, normal or deep overbite (OB), and mild-to-moderate dental crowding (<5 mm) who underwent nonextraction fixed OT with ("bonded" group) or without ("not-bonded" group) bonding of second molars. Patient treatment records, pre- and posttreatment digital models, lateral cephalograms, and orthopantomograms were assessed. The evaluated outcomes included leveling of the curve of Spee (COS), OB, control of incisor mandibular plane angle (IMPA), number of emergency visits (related to poking wires and/or bracket failure of the terminal molar tubes), treatment duration, and C-R-Eval. Treatment variables were compared across time points and among groups.

Results: The sample included 30 patients (mean age 16.07 ± 1.80 years) in the bonded group and 32 patients (mean age 15.69 ± 1.86 years) in the not-bonded group. The mean overall C-R-Eval score was significantly higher (P < .001) in the not-bonded group (25.25 ± 3.98) than in the bonded group (17.70 ± 2.97). There were no significant differences in mean changes of COS, OB, IMPA, or treatment duration among groups. The mean number of emergency visits was significantly higher in the bonded (3.3 ± 0.6) than the not-bonded group (1.9 ± 0.4) (P < .001).

Conclusions: Bonding of second molars enhances the outcome of nonextraction fixed OT as demonstrated by the C-R-Eval without increasing treatment duration, irrespective of more emergency visits.