American Journal of Orthodontics and Dentofacial Orthopedics最新文献

Introduction: This study aimed to investigate the accuracy of dental model printing using 2 different layer height settings and how these settings affect the fabrication of thermoformed retainers.

Methods: Subjects were recruited from the Department of Orthodontics at Case Western Reserve University and scanned according to specific selection criteria. A total of 30 stereolithography files were produced and used as reference files. The stereolithography files were printed at the recommended layer height of 100 μm and 170 μm with a Sprint Ray Pro 95 3-dimensional (3D) printer (Sprint Ray, Los Angeles, Calif). All printed models were scanned using the same iTero intraoral scanner (Align Technology, San Jose, Calif) as was used for the initial intraoral scan as well. The accuracy of the printed models was based on the evaluation of root mean square values resulting from 3D superimpositions. Afterward, vacuum-formed retainers were fabricated. The vacuum-formed retainers were evaluated by the patient and an American Board of Orthodontics-certified orthodontist.

Results: No difference was observed in the maxillary arch (P = 0.85) and the mandibular arch accuracy (P = 0.08) by assessing the root mean square values. No difference was observed in the doctor retainer score of the maxillary retainers (P = 0.37) and the mandibular retainers (P = 0.77). There was no difference in the patient retainer score of the maxillary (P = 0.08) and the mandibular retainers (P = 0.22) when comparing retainers. Conversely, less printing time was observed when printing the models with 170 μm compared with 100 μm (P <0.001).

Conclusions: The accuracy of a dental model printed with a Sprint Ray Pro 95 3D printer was not affected by the 100 or 170 μm layer height. Orthodontists and patients did not detect a statistically significant difference in retainer fit.

Introduction: The objective of this study was to evaluate the effects of the miniplate application sites in the maxilla and the applied force vector changes during skeletally supported facemask application in adolescent patients with unilateral cleft lip and palate (UCLP) using finite element model (FEM) analysis.

Methods: A FEM was obtained from a cone-beam computed tomography image of a 12-year-old female patient with UCLP. Miniplates were placed on 3 different sites of the maxilla; 500 g of advancement force was applied bilaterally, parallel (0°), and downward (-30°) to the occlusal plane. Von Mises stress and displacement in the nasomaxillary complex were analyzed.

Results: Von Mises stress values were higher at 0° force mechanics in the nasomaxillary complex in 3 different miniplate sites. In all scenarios, stresses were higher in zygomaticotemporal, zygomaticofrontal, and pterygopalatine sutures. In the y-axis, the amount of displacement was higher in the 0° force mechanics in all models. Midface advancement and clockwise rotation of the nasomaxillary complex were observed in the -30° force mechanics over mini plates placed on the lateral nasal wall and among the premolars, whereas counterclockwise rotation occurred in all miniplate placement sites with 0° force vector.

Conclusions: In patients with skeletal Class III maloclussion with UCLP, anterior placement of miniplates in the maxilla may be a more precise alternative when midface advancement and clockwise rotation of the nasomaxillary complex are desired. This FEM study demonstrated that more anterior placement sites and a 30° force vector is efficacious for maxillary clockwise advancement in UCLP.

Introduction: This study aimed to assess the root resorption and alveolar bone changes of maxillary incisors volumetrically and 3-dimensionally in patients with Class II Division 1 malocclusion who underwent treatments involving the extraction of 4 first premolars with conventional fixed appliances (FAs) vs clear aligners (CAs).

Methods: A total of 320 maxillary incisors from 80 patients were assessed and divided into 2 groups (FAs and CAs), each possessing similar baseline characteristics. Pretreatment and posttreatment cone-beam computed tomography scans were used to analyze linear and volumetric orthodontically induced inflammatory root resorption, alveolar bone thickness (ABT), alveolar bone height (ABH), as well as anteroposterior and vertical movements of maxillary incisors.

Results: Both groups revealed a significant reduction in palatal ABT and an increase in labial ABT in both the central and lateral incisors. The total ABT reduction was more pronounced in the FAs group than in the CAs group (P <0.005). In terms of ABH, FAs treatment resulted in more labial and palatal marginal alveolar bone resorption around the maxillary incisors. The root length and volume losses in the CAs group were significantly less than those in the FAs group: 0.90 ± 0.97 vs 1.85 ± 1.18 mm and 19.59 ± 8.75 vs 24.28 ± 10.05 mm³, respectively. The axial inclination was significantly less in the CAs group than in the FAs group: 8.83 ± 8.73 vs 2.64 ± 12.31°.

Conclusions: Treatments of Class II Division 1 malocclusion with FAs and CAs appeared to cause a statistically significant palatal ABT reduction and maxillary incisors root resorptions, with the FAs treatment causing a more significant effect. Both treatment modalities significantly reduced the ABH, with the greatest reduction found on the lateral incisors' palatal side in the FAs group. The CAs treatment resulted in a more significant incisor lingual tipping.

Introduction: The objective of this study was to compare the dental and skeletal changes promoted by the miniscrew-anchored cantilever and pendulum appliance for Class II correction.

Methods: This retrospective study involved 52 patients with Class II malocclusion divided into 2 groups according to the treatment received: the miniscrew group (MG) with 23 patients (14 females and 9 males; mean initial age of 12.42 years) treated using the miniscrew-anchored cantilever, and the pendulum group (PG) with 29 patients (21 females and 8 males; mean initial age of 13.60 years) treated using the pendulum appliance. Lateral cephalograms and digital dental models were obtained and analyzed in 2 phases: pretreatment and postdistalization. Intergroup comparisons were performed using t test, Mann-Whitney test, and multivariate analysis of covariance test for covariates (P <0.05).

Results: Both groups exhibited similar molar distalization (3.25 ± 1.68 mm for MG and 2.90 ± 2.17 mm for PG). The MG showed distalization of premolars (2.03 ± 2.09 mm) and incisors (1.70 ± 2.27 mm), whereas the PG exhibited mesialization of premolars (3.24 ± 2.01 mm) and incisors (2.30 ± 2.60 mm). A greater distal rotation (20.20° ± 5.73° for MG and 4.26° ± 6.41° for PG; P <0.001) and smaller distal angulation (8.55° ± 3.75° for MG and 14.36° ± 5.67° for PG; P <0.001) of the maxillary first molar was observed in the MG when compared with the PG.

Conclusions: Both devices were effective for Class II molar distalization. The miniscrew-anchored cantilever was able to control the side effects of mesialization in the incisors and premolars during distalization when compared with distalization with a pendulum appliance.

Introduction: The primary aim of this study was to assess the amount and long-term stability of orthodontically created bone in patients with agenesis of maxillary lateral incisors after canine distalization. The secondary aim was to explore the impact of patient age on the process of alveolar bone resorption.

Methods: A group of patients with agenesis of the maxillary permanent lateral incisor was examined at 4 time points: the beginning of orthodontic treatment (T1, n = 80), the end of treatment (T2, n = 80), 2-5 years after treatment (T3, n = 79), and 12-15 years after treatment (T4, n = 32). The width of the edentulous alveolar bone was measured from study casts at the level of the bone ridge (point A) and 5 mm apically from the alveolar ridge (point B). Alveolar ridge height was also recorded using panoramic radiographs at all time points. Paired t tests, 2-sample t tests, Friedman test with Bonferroni correction, Spearman`s correlation, and linear regression tests were used to analyze the data.

Results: The alveolar ridge width was reduced by an average of 0.44 mm at point A and 0.47 mm at point B during the 12-15 years after treatment (T2-T4) and by 0.21 mm and 0.19 mm during the last 10 years (T3-T4). The alveolar ridge height was reduced by 0.59 mm between T2 and T4 and by 0.05 mm between T3 and T4. All reductions in ridge width and height were statistically significant (P <0.05). However, no significant correlation was observed between patient age and changes in alveolar bone parameters (P >0.05).

Conclusions: Although the reductions in alveolar ridge dimensions were statistically significant, the orthodontically created bone after canine distalization remained stable 12-15 years after treatment in both the horizontal and vertical dimensions. Patient age did not significantly influence alveolar bone changes.

Introduction: Increased preoperative anxiety may have an adverse impact on the patient experience. This qualitative study therefore aimed to explore those factors affecting anxiety in the approach to orthognathic surgery.

Methods: A total of 28 orthognathic patients who had completed their presurgical orthodontic treatment and were within 8 weeks before their surgery underwent one-to-one in-depth interviews. The interviews explored their experience in the preoperative period, with the focus on aspects relating to anxiety. Interviews were audio-recorded and transcribed verbatim, and data were then analyzed using a thematic framework approach.

Results: Eight themes and associated subthemes were identified. The first theme related to time and described the approach to the surgery and the transience of the side effects. The second theme discussed control and how the need for control may affect anxiety; the third focused on fear related to the surgery and the element of "the unknown." The fourth theme highlighted the importance of trust between patients and clinicians, whilst the fifth focused on information and its delivery, which was crucial for managing uncertainty. The sixth theme centered on expectations about the surgery and the patient's ability to cope, and the seventh discussed coping strategies that were effective in alleviating anxiety. The final theme focused on the benefits of a strong, effective support system in reducing anxiety. No distinct typologies emerged from the data. Recommendations for consideration by clinicians are presented.

Conclusions: The findings provide a novel insight into the multifactorial nature of preoperative anxiety in orthognathic patients and also highlight the important role of the clinical team in creating a supportive environment to help reduce patient anxiety.

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.

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 use of artificial intelligence (AI) is growing quickly and has already had a significant impact on the practice of orthodontics. This study aimed to explore the degree to which the study and use of AI have been integrated into accredited postgraduate orthodontic programs in North America.

Methods: An anonymous electronic survey was sent to each of North America's 74 orthodontic residency programs, requesting information from either the program director or department chair. Data were collected and analyzed using SPSS (version 28; IBM, Armonk, NY) and Excel (Microsoft, Redmond, Wash).

Results: Forty-one valid surveys were analyzed. Among the respondents, 56.1% had implemented or planned to implement AI instruction into their program. Among those who reported using this technology, 60.9% indicated that they have applied these principles for research purposes. Most respondents (87.8%) noted that they have not developed seminars and/or AI training to be included in their curriculum, whereas residents in 17.1% of respondent programs have advocated for these modifications. Lack of expertise and availability in the schedule (71.4%) are common challenges associated with the dearth of curriculum changes. Most programs (68.3%) encouraged their residents to attend continuing education for AI fundamentals, while 75.6% reported that they do not encourage their residents to use AI for patient care, research, or didactic assignments. Several programs (68.3%) reported not updating their academic manuals and syllabi with new AI policies, nor have they installed new AI detection software (80.5%).

Conclusions: More than half of orthodontic residencies have implemented AI into their program in some capacity. The continual advancements of AI algorithms will require modifications to orthodontic residency programs. AI-related education should be implemented into academic curricula to provide residents with the tools necessary to thrive in an AI-driven practice.

Introduction: Used clear aligner trays are often indiscriminately disposed of with general plastic waste and incinerated. This study aimed to analyze the smoke composition from incinerating 2 common aligner materials: glycol-modified polyethylene terephthalate (PET-G) and polyurethane.

Methods: Each of the 2 materials in triplets was thermoformed. The thermoformed trays were shredded and subjected individually to open-fire combustion, ignited using a methane torch, in a specially designed combustion chamber. The resultant smoke was collected and analyzed using gas chromatography-mass spectrometry to study its in-depth composition.

Results: A total of 20 peaks, corresponding to 20 compounds, were identified from each of the 2 material samples. O-xylene (21.06%) showed the maximum concentration in the PET-G sample, whereas 1,4-dimethyl-1,3-cyclohexadiene in polyurethane (18.88%). The first peak in the PET-G sample corresponded to benzene with a relative concentration of 5.18%. Four compounds were common to both samples: 1,4-dimethyl-1,3-cyclohexadiene; 1,3-cyclohexadiene, 2,3-dimethyl-; 1-hydroxymethly-4-methylenecyclohexane; and cyclohexanemethanol, 4-methylene-.

Conclusions: Benzene, a group 1 carcinogen, was identified in the PET-G smoke sample, whereas tetrahydrofuran, a suspected carcinogen, was found in the polyurethane sample. Some compounds were hazardous, whereas most were skin, eye, and respiratory irritants. Possible mitigation strategies include proper case selection, efficient manufacturing, direct 3-dimensional printing, and developing biodegradable materials. Clinicians can set up 'used aligner collection points' to ensure responsible disposal. Proper disposal guidelines and stringent regulations are the need of the hour.