American Journal of Orthodontics and Dentofacial Orthopedics最新文献

Introduction: Extraction of a single mandibular incisor may be prescribed in conjunction with clear aligner orthodontic treatment. The accuracy of therapeutic mesiodistal tooth positioning for the remaining mandibular anterior teeth for such patients has not been comprehensively evaluated. This retrospective study compared the predicted and achieved mesiodistal tooth movements in the mandibular anterior region for patients treated with Invisalign (Align Technology, Santa Clara, Calif), along with the influence of aligner attachments and the frequency of aligner change.

Methods: A sample of 83 subjects who had undergone Invisalign treatment with a single mandibular incisor extraction was collected from an existing database. The pretreatment tooth positions, the predicted mesiodistal tooth movement, and the achieved outcomes were measured for the remaining mandibular anterior teeth using Geomagic Control X metrology software (3D Systems, Rock Hill, SC). The predicted and achieved mesiodistal tip movements were analyzed and compared.

Results: Regression analysis revealed significant differences (P <0.001) between the predicted and achieved mesiodistal tooth positioning for incisors and canines. For every degree of predicted incisor mesiodistal tip, 78.89% of this tip was achieved (R² = 0.4901). For every degree of predicted canine tip, 54.16% was clinically expressed (R² = 0.5965). The accuracy of mesiodistal tip expression was not significantly affected by the prescribed number of aligners, 1-week vs 2-week aligner change protocols, or the presence of attachments (P >0.05). In addition, incisors were less likely to express the correct direction of the mesiodistal tip predicted than canines (P = 0.020).

Conclusions: A shortfall between the predicted and clinically achieved expression of mesiodistal tooth movement with Invisalign was found for the anterior teeth after a mandibular incisor extraction. The number of aligners, duration of aligner wear, and specific attachment designs were not found to significantly influence the accuracy of the achieved mesiodistal tip movements.

Introduction: Directly printed aligners (DPAs) are gaining in popularity, potentially streamlining manufacturing, decreasing environmental waste, and offering enhanced adaptation and tailoring. This transition has been facilitated by advances in materials, software, and production. Although DPAs may have enhanced versatility and application in the management of more complex malocclusions, there is little research evaluating their effectiveness.

Methods: A total of 54 patients undergoing treatment with DPAs were evaluated for occlusal improvement, overall treatment duration, and adverse effects. Regression models were fit to evaluate the association between the need for refinement, final peer assessment rating (PAR) score, and independent variables, including the total number of aligners and treatment indications.

Results: The mean number of aligners in the initial plan was 7.1 ± 2.9 and 5.1 ± 4.3 in maxillary and mandibular arches. Refinement was required in 40.8% (n = 20). The pretreatment PAR score of 17.01 ± 7.93 showed a significant improvement (86.6%), with a final PAR score of 2.25 ± 1.15. Minor complications were noted in 3 participants. The need for refinement was unrelated to the total number of aligners (odds ratio, 1.05; 95% confidence interval, 0.94-1.18; P = 0.36). There was weak evidence of an association between the final PAR score and the total number of aligners (odds ratio, -0.03; 95% confidence interval, -0.07 to 0.003, P = 0.07).

Conclusions: On the basis of this preliminary retrospective evaluation, DPAs may be used to manage mild-moderate malocclusion, producing a significant reduction in PAR score. Nevertheless, additional prospective research is required to confirm these findings and compare the relative merits of DPAs to alternatives.

This article describes a hypothesis for bone recovery after iatrogenic dehiscences or fenestrations. When roots are moved out of the alveolar bone, the periodontal ligament and periosteum form a bilayer membrane (sandwich) over the exposed root. If the root is allowed to relapse back toward its original position, bone recovery will occur between the periodontal ligament and periosteum.

Introduction: This study aimed to compare and evaluate time-dependent biofilm formation and microbial adhesion on 6 different clear aligner systems: Invisalign (Align Technology, San Jose, Calif), Clarity (3M ESPE Maplewood, Minn), ClearCorrect (Institut Straumann AG, Basel, Switzerland), Smartee (Smartee Denti-Technology, Shanghai, China), Orthero (Orthero, Istanbul, Turkey) and Graphy (Graphy Inc, Seoul, South Korea).

Methods: Streptococcus mutans (ATCC 25175) and Lactobacillus acidophilus (ATCC 4356) were used to evaluate the microbial adhesion and biofilm formation on orthodontic clear aligners at the 0, 24, 48, 72, 96, 120, 168, and 240 hours. Two-way repeated measures analysis of variance (Greenhouse-Geisser) test and post-hoc Bonferroni T2 tests were used for statistical evaluation. The statistical significance level was set at P <0.05.

Results: It was found that more bacterial formation occurred on ClearCorrect than on Smartee at 120, 168, and 240 hours (P <0.05). It was observed more biofilm formation at 168 hours on Graphy than on Smartee (P <0.05). It was found that S mutans + L acidophilus formed more biofilm at 120 and 168 hours on Graphy than on Invisalign (P <0.05).

Conclusions: Elevated biofilm formation across all materials carries substantial clinical implications. Orthodontists and patients should remain aware of the increased risk of microbial colonization with extended aligner usage.

Introduction: The objective of this study was to compare the differences in anchorage and torque control among the Tweed edgewise, Roth, and physiological anchorage Spee-wire systems (PASS) appliances (Zhejiang Xinya Technology Co, Ltd, Hangzhou, China).

Methods: A sample of 90 adolescent patients with Angle Class II Division 1 malocclusion (30 Tweed edgewise appliances, 30 Roth appliances, and 30 PASS appliances) with maximum anchorage requirements in the maxilla were collected for this study. The pretreatment baseline levels of the 3 groups were compared initially, and then the differences between the 3 appliances in anchorage and torque control were analyzed after superimposing the pretreatment and posttreatment lateral cephalograms and maxillary 3-dimensional (3D) digital models, respectively.

Results: There was no statistical difference in the pretreatment baseline levels of 3 groups, including gender, age, sagittal skeletal types (ANB), vertical skeletal types (SN-GoGn), anchorage requirements, and occlusal plane inclination (SN-OP). After superimposing the pretreatment and posttreatment lateral cephalograms and 3D digital models, respectively, no statistical differences were observed between the measurement results obtained from lateral cephalograms and 3D digital models. Among the measurement variables assessed in this study, statistical differences were observed in the mesial displacement of maxillary first molars, the incisor retraction, and the torque variation of maxillary central incisors among the 3 groups. Specifically, the Tweed group exhibited lower mesial displacement of maxillary first molars compared with the PASS and Roth groups. Furthermore, the Tweed group exhibited the greatest amount of incisor retraction and torque variation of maxillary central incisors, followed by the Roth group and then the PASS group. The remaining measurement variables for the 3 groups showed no statistical differences, including vertical variation of maxillary first molars and central incisors, torque variation of maxillary first molars and canines, mesiodistal inclination variation of maxillary first molars and canines, width variation between maxillary first molars, and width variation between maxillary canines.

Conclusions: Compared with contemporary preadjusted straight wire appliances, the Tweed edgewise appliance has superiority in molar anchorage control. In contrast, compared with the Roth appliances, the PASS appliances without any auxiliary anchorage devices could make full use of physiological anchorage to achieve adequate control of molar anchorage. Clinical orthodontists may need to pay extra attention to physiological anchorage. The difference in torque control varies depending on the respective characteristics of bracket designs.

Introduction: The aim was to compare the soft tissue changes in pretreatment and posttreatment facial scans of patients who had undergone various orthopedic treatments vs a control group of untreated growing patients.

Methods: Facial scans were performed before (T0) and after (T1) orthopedic treatment in 15 patients prescribed rapid palatal expander (RPE), 15 cervical headgear (HG), and 15 facemasks (FM), as well as 6 months apart in 15 untreated growing patients. After best-fit scan alignment using Geometric Control X software (3D Systems Inc, Rock Hill, SC), a 3-dimensional (3D) analysis of soft tissue changes was performed, comparing 3D reference points (total 22) and 8 areas on T0 and T1 scans. Kruskal-Wallis nonparametric tests and pairwise comparison with Bonferroni's correction were applied to identify any statistically significant differences among groups (P <0.05). All analyses were conducted with SPSS software (version 28; IBM, Armonk, NY).

Results: At T1, reduced soft tissue projection was found at the nose and upper lip in the HG group, the lower lip in the HG and RPE groups, and the chin in the FM and RPE groups. The RPE group displayed a statistically significant increase in facial divergence, confirmed by gnathion position (RPE vs FM [P = 0.018] and RPE vs control [P = 0.046]), as well as an increase in the soft tissue projection of both cheeks (left cheek in range of 1-2 mm [P = 0.030] and range of 0 to -1 mm [P = 0.022]; right cheek in range of 1-2 mm [P = 0.003] and range -1 to -2 mm [P = 0.001]). There were no clinically significant differences among groups in mandibular right and left body areas.

Conclusions: The 3D facial analysis revealed significant differences in soft tissues among orthopedic treatments, especially at the upper and lower lip and chin areas, as compared with untreated patients.

Introduction: We assessed the accuracy and fit of 3-dimensional (3D)-printed indirect bonding (IDB) trays fabricated using various photopolymer resin materials.

Methods: A maxillary plaster model and 60 plaster replicas were created. IDB trays with arbitrary bracket configurations were 3D-printed using 3 hard resins (Amber [AB], TC85DAC [TC], Orthoflex [OF]) and 3 soft resins (IBT [IT], IDB2 [ID], and MED625FLX [MD]). A reference plaster model with a computer-aided design-designed IDB tray attached with nonfunctional, arbitrary bracket configurations on the buccal surface serving as reference points for measurement was superimposed on scanned plaster replicas holding 3D-printed trays to assess transfer accuracy and clinically acceptable error. Printing accuracy was assessed by comparing computer-aided design trays to printed trays, and tray fit was measured by the gap volume between the tray and plaster replica using a Fit-Checker (GC Corp, Tokyo, Japan).

Results: Six tray groups showed significant linear transfer errors, particularly in the vertical direction (0.15 mm [95% confidence interval {CI}, 0.10-1.15]; P = 0.004). The OF group exhibited the largest vertical error (0.27 mm [95% CI, 0.19-0.35]), whereas the ID group had the smallest (0.10 mm [95% CI, 0.06-0.14]). Angular errors did not exhibit significant differences across the groups. Linear precision error was the highest in OF, followed by ID, TC, and MD, then AB and IT (P <0.001). Of all tray groups, 90.1% and 68.8% met the clinically acceptable linear (<0.25 mm) and angular errors (1°).

Conclusions: Linear errors, particularly vertical errors, are more material-dependent than angular errors. Gap volume alone was not a reliable predictor of IDB tray accuracy. Therefore, material-specific designs are needed to control the optimal fit and facilitate precise bracket placement.

Introduction: This study aimed to identify the link between alloy microstructures and the nanomechanical properties of different orthodontic archwires containing nickel-titanium (NiTi) by sensing sliced areas. Previous studies have focused on analyzing and contrasting physical properties such as microhardness, elasticity modulus, and resistance; therefore, the trend is to consider microstructural characteristics in detail.

Methods: Thirty archwire samples from 3 different commercial brands, American Orthodontics (AO), 3M Unitek (3M), and Borgatta, were analyzed through scanning electron microscopy and energy-dispersive x-ray spectroscopy, transmission electron microscopy, atomic force microscopy, Berkovich nanoindentation, and microtensile microscopy to determine their chemical-crystallographic characteristics and nanomechanical and bending characteristics.

Results: The identified formulations of AO and 3M had averages of 20 wt%, for Ni and 15.4 wt% for Ti, with lower concentrations for Borgatta. Alloys of Ni and Ti were distributed in different concentrates in the matrix of the archwires. The nanomechanical properties showed high values of the elastic modulus (82.8 ± 3.6 GPa) and hardness (6.4 ± 1.2 GPa) and a minor deformation degree of 0.38% for the AO wires, although the bending strength exhibited the highest values for 3M. No corrosion was observed with a prolonged hydrolytic attack on the surface of any of the wires (0.0-0.5 National Bureau of Standards units).

Conclusions: The highest nanomechanical properties and bending characteristics were observed for wires with higher NiTi precipitate contents, which were distributed differently in the alloy overall in the matrix. The nanoindentations sensed in different areas evidenced different mechanical properties for NiTi depending on its concentrations of Ti and enucleations.

Introduction: The objective of this study was to assess the relative contribution of genes to shape variation in the permanent dental arches in individuals of Western European descent.

Methods: The dental casts from 64 monozygotic and 38 dizygotic twins, housed in the Adelaide Dental School's twin record collection, Australia, were assessed. The subjects were of Western European descent, with a mean age of 19.4 ± 5.4 years. Dental casts were scanned using a 3-dimensional scanner (3Shape E4, 3Shape, Copenhagen, Denmark), and landmarks were placed on incisal edges and cusp tips of canines, premolars, and molars. Procrustes superimposition and principal components analysis were applied to examine shape variation. Two-block partial least-squares analysis was used to assess shape covariation between arches. Structural equation modeling was utilized to decompose observed shape variation into genetic and environmental components using the normal assumptions of the twin model.

Results: The first 3 principal components (PCs) of the maxillary and mandibular arch were meaningful, accounting for 53% and 50% of the variation in shape space, respectively. The PCs represented shape variability as follows: PC1 - arch depth-width ratio, PC2 - arch taper, canine position (and first premolar rotation for the mandibular arch), and PC3 - incisor displacement and rotation. Genetic modeling indicated that a model incorporating additive genetic and unique environmental factors optimally explained the observed variation for all meaningful PCs. Within shape space, most of the variation in maxillary and mandibular arches exhibited moderate to high heritability (h² = 0.61-0.74). Maxillary and mandibular dental arches had strong and significant shape covariation, with high heritability in their reciprocal influences on shape (h² = 0.72-0.74; r_pls coefficient = 0.87; P <0.05).

Conclusions: In this cohort, dental arch shape variation was predominantly influenced by genetic factors. High covariation and heritability were observed between the maxillary and mandibular dental arches. This information may help inform decisions around orthodontic intervention.