Journal of Orofacial Orthopedics-Fortschritte Der Kieferorthopadie最新文献

Purpose: This observational study aimed to evaluate the stability of unilateral posterior crossbite (UPXB) correction with the functional appliance function generating bite (FGB appliance) during follow-up and its effects on craniofacial growth.

Materials and method: A total of 102 age- and gender-matched patients were included: 51 with UPXB (male [M] = 19; female [F] = 32; mean age ± standard deviation [SD] = 7.6 ± 1.4 [years.months]) and 51 controls (C; M = 19; F = 32; mean age ± SD = 7.9 ± 1.3). UPXB was corrected with the FGB appliance. Study casts were collected before treatment (T0), after correction (T1), after a follow-up of 3.7 ± 1.6 [years.months] (T2) and different transversal measurements were performed with calipers: intermolar (IMD), intermolar gingival (IMGD), intercanine (ICD), and intercanine gingival distances (ICGD). In treated patients, in addition, lateral cephalometric tracings were analyzed at T0 and T2.

Results: At T0, all maxillary measurements were significantly smaller in the UPXB group compared to the controls (p < 0.001). Between T0 and T1, all maxillary variables increased significantly in the UPXB group (p < 0.001; IMD +4.3 ± 2.1 mm; ICD +3.1 ± 2 mm). Between T1 and T2, maxillary IMD increased further (p < 0.05; +2.2 ± 2 mm). The mean T0-T2 increases were 6.6 ± 2.6 mm (IMD) and 4.3 ± 2.6 mm (ICD). At T0, the cephalometric analysis showed significantly stronger mandibular clockwise rotation (p < 0.01) in the UPXB group compared to the control group. Between T0 and T2, the UPXB group showed a significant reduction of mandibular (p < 0.001; SpP-CoOr T0 = -3.47°± 4.38, T2 = -1.14°± 4.01) and occlusal plane (p < 0.01; SpP-Oc T0 = 11.37°± 3.91, T2 = 9.86°± 3.83) clockwise rotation, and of intermaxillary divergence (p < 0.01; SpP-GoGn T0 = 27.8°± 5.39, T2 = 26.65°± 5.49).

Conclusions: Treatment of UPXB with the FGB appliance effectively increased maxillary transversal width measurements, especially in the posterior region, even after follow-up, indicating stable results. Concurrently, mandibular clockwise rotation was reduced, indicating control of the vertical dimension.

Aim: The purpose of the present study was to compare the interproximal accuracy (IA) of two different CAD/CAM (computer-aided design/computer-aided manufacturing) manufactured and conventionally bent retainers.

Materials and methods: On 20 digitized debonding casts (10 upper, 10 lower), a canine-to-canine retainer was designed using two different CAD/CAM software: OnyxCeph^® (Image Instruments, Chemnitz, Germany) and FixR™ (YOAT Corp., Lynnwood, WA, USA). Each design was bent using the Bender II™ retainer bending machine (YOAT Corp.) and 3‑ or 6‑stranded twistflex wires (0.018-inch Dentaflex^®, Dentaurum, Ispringen, Germany), respectively. For each cast, one CAD/CAM machine cut retainer (Memotain^®, SCHEU DENTAL custom-made, Hilden, Germany) was fabricated and one retainer was bent manually by a dental technician using the 6‑stranded wire. All retainers were passively waxed on the dental casts and digitized using a laboratory scanner (Atos, Carl Zeiss IQS Deutschland, Oberkochen, Germany). For each of the five interproximal areas, IA was measured (1) as vertical distance between retainer and the reference retainer plane and (2) as horizontal distance between the interproximal reference point and the retainer in millimeters. For both directions, it was assumed that the smaller the distance, the higher the interproximal accuracy of the retainer. Statistical analysis was performed using Mann-Whitney and Kruskal-Wallis tests.

Results: Considering the vertical deviation, significant differences of interproximal accuracy were seen between the jaws (upper 0.25 mm > lower 0.18 mm, p < 0.001), planning software (FixR 0.25 mm > OnyxCeph 0.21 mm, p = 0.03) and settings (upper jaw: CAD/CAM bent [FixR] 0.34-0.32 mm > manually bent 0.27 mm > CAD/CAM bent [Onyx] 0.23-0.18 mm > CAD/CAM cut 0.17 mm, p = 0.001; lower jaw: CAD/CAM bent [FixR 3‑stranded and Onyx] 0.22-0.21 mm > manually bent 0.18 mm > CAD/CAM bent [FixR 6‑stranded] 0.13 mm > CAD/CAM cut 0.10 mm, p = 0.004). For horizontal deviation, significant differences were observed between the jaws (upper 0.97 mm > lower 0.66 mm, p < 0.001), planning software (OnyxCeph 0.90 mm > FixR 0.72 mm, p < 0.001), settings (upper jaw: CAD/CAM bent [Onyx] = CAD/CAM cut 1.16-1.10 mm > CAD/CAM bent [FixR] 0.96-0.89 mm > manually bent 0.76 mm, p < 0.001; lower jaw: CAD/CAM bent [Onyx] 0.84-0.71 mm > CAD/CAM cut 0.66 mm = CAD/CAM bent [FixR] 0.66-0.63 mm > manually bent 0.51 mm, p < 0.001) and location of the interdental area in the upper jaw (13-12 = 22-23 > 22-21 > 11-21 > 12-11, p < 0.001). The wire quality had no significant impact in either of the dimensions.

Conclusion: Interproximal accuracy in the vertical plane was achieved best by CAD/CAM cut retainers, while horizontally, manually bent retainers were the most accurate. Overall, the accuracy of lower retainers seems clinically acceptable for their u

Purpose: This in vitro study aimed to examine aging-associated adaptations in the mechanoresponse of periodontal ligament fibroblasts (PdLFs) and explore a potential regulatory role of growth differentiation factor 15 (GDF15).

Methods: Replicative senescence was induced in cultured human PdLFs (hPdLFs) by repeated enzymatic subcultivation as a valid in vitro aging model. The senescent phenotype was assessed by analyzing cellular morphology, proliferative capacity, and senescence marker expression. Furthermore, GDF15 levels were measured and subsequently modulated by small interfering RNA(siRNA)-mediated knockdown and by ponsegromab, a novel GDF15-neutralizing antibody. Tensile and compressive forces were applied using BioFlex® Culture Plates (FLEXCELL®, Dunn Labortechnik, Asbach, Germany) and sterile glass plates, respectively. The mechanoresponses of hPdLFs were characterized by analyzing pro-inflammatory cytokine levels and the activation of immune cells as well as of bone-remodeling osteoblasts and osteoclasts.

Results: Aged hPdLFs exhibited decreased proliferation, increased β‑galactosidase activity, and morphological changes indicative of cellular senescence. Elevated baseline and force-induced intra- and extracellular GDF15 levels were observed in aged hPdLFs correlating with enhanced pro-inflammatory cytokine expression and immune cell activation. While aged hPdLFs showed reduced activation of osteoblasts in response to tensile forces, compressive forces led to increased osteoclast activation. Remarkably, modulating intra- and extracellular GDF15 levels partially restored the deregulated activation of bone-remodeling cells.

Conclusion: Aging altered the mechanobiological response of PdL fibroblasts by promoting a hyperinflammatory microenvironment and shifting bone remodeling towards degenerative processes. Senescence-associated increases in GDF15 contributed to these changes by force-dependent intra- and extracellular signaling pathways. Targeting GDF15 could offer a therapeutic potential to optimize bone remodeling and improve orthodontic care for the elderly.

Background: Orthodontic treatment offers numerous benefits, but prolonged treatment times can lead to increased costs and sequelae. Piezoelectric-assisted procedures like piezocision show promise in accelerating treatment, though their efficacy is not yet fully confirmed, nor are they widely adopted. This study aimed to evaluate the effectiveness of piezocision for orthodontic patients.

Methods: A meta-analysis of 16 randomized controlled trials (RCTs) involving 371 patients was conducted to compare piezocision with conventional orthodontic treatment. Systematic searches were performed in PubMed, EMBASE, and Cochrane Library databases. Statistical analyses included mean difference (MD) with 95% confidence intervals (CI) using a random-effects model. The study protocol was registered in PROSPERO (CRD42022335350).

Results: Piezocision significantly reduced treatment duration compared to conventional methods (MD = -39.60, 95% CI -59.67 to -19.52), though total treatment time was investigated by only one research group. Posttreatment pain was significantly higher in the piezocision group on day 1 (MD = 17.83, 95% CI 5.75-29.92) but showed no significant differences on day 7 (MD = 4.86, 95% CI -0.74 to 10.47). Despite similar pain levels by day 7, patients expressed preferences for conventional orthodontic treatment. The reduction rate of Little's irregularity index was more efficient in the piezocision group during the first month (MD = 1.58, 95% CI -0.13 to 3.29), with no significant differences at the end of alignment (MD = 1.04, 95% CI -0.06 to 2.15).

Conclusion: Piezocision resulted in reduced orthodontic treatment duration compared to conventional methods. However, considering the study limitations and patient preferences, future research with larger sample sizes and more RCTs is needed to validate these findings and assess the long-term clinical implications before widespread adoption.

Objectives: To establish cephalometric norms for African American adults with normal occlusion and balanced soft tissue profiles in the Greater Philadelphia region and compare these findings with existing African American norms.

Materials and methods: A total of 650 orthodontic records from adult African American subjects were reviewed. Normal occlusion was defined based on Angle's class I molar relationship, an overbite of 20-30% or greater than 0 mm and less than 3 mm, an overjet ranging from 1-3 mm, absence of crossbites, minor dental crowding, and gaps or rotations not exceeding 2 mm, along with a balanced facial profile. According to these criteria, 34 lateral cephalograms (25 females, 9 males; mean age 28.4 ± 12.7 years) were selected. These lateral cephalograms were digitally traced using Dolphin Imaging software (version 12.0, Chatsworth, CA, USA), and the obtained cephalometric measurements were compared with established African American norms from existing literature.

Results: Skeletally, African American subjects from the Greater Philadelphia region demonstrated smaller vertical measurements, characterized by reduced SN-GoGn, FMA, and Y‑axis angles compared to previously published norms for the African American population. The skeletal sagittal relationship indicated a more anteriorly positioned maxilla relative to established Caucasian norms. Dental evaluations revealed a slight increase in upper incisor inclination and a reduced interincisal angle, as evidenced by measurements such as the 1/to SN, 1/to FH, and 1/to NA angles when compared to existing African American norms. Additionally, subjects from the Greater Philadelphia region exhibited a more protrusive lower lip compared to previously reported norms for African Americans.

Conclusion: Our findings indicate that cephalometric norms vary by both ethnicity and geographic region, underscoring the necessity of establishing population-specific standards to ensure accurate diagnosis and effective treatment planning.

The use of computed tomography (CT) or cone-beam CT (CBCT) enables three-dimensional (3D) cephalometric analysis but exposes patients to high levels of radiation, while conventional X‑ray imaging provides projected measurements for two-dimensional (2D) cephalometric analysis with lower radiation exposure. The presented tool overcomes the disadvantages of both imaging modalities for performing 3D cephalometric analysis. Our tool aims to evolve a 3D framework from the fusion of conventional lateral and posteroanterior (PA) X‑ray images for performing 3D cephalometric analysis. Lateral and PA image datasets of 27 patients were used to validate the proposed tool. A total of 29 cephalometric landmarks were plotted on each image, and therefore, a total of 406 measurements were computed on each patient's image. An image registration-based method was implemented using the MATLAB (MathWorks, Natick, MA, USA) programming language for the prediction of 3D landmarks and computation of cephalometric measurements. The same 406 measurements were compared with measurements made on corresponding CT images. Statistical parameters, e.g., average error, standard deviation, t‑test, and correlation coefficient were computed to evaluate the performance of the proposed tool. The average mean error and average standard deviation of the 406 measurements were 2.40 and 1.77 mm, respectively. Using the proposed tool, a 3D cephalometric analysis can be performed using two X‑ray images, avoiding the need for CT/CBCT images. The proposed tool is the first method to evolve 3D cephalometric landmarks and measurements from two conventional X‑ray images, and the overall results were satisfactory.

Purpose: Using a commercial orthodontic treatment planning system, tooth movements were simulated to analyse how precise predefined movements can be determined by three different superimposition methods. Additionally, a retrospective analysis on clinical patient models before and after orthodontic treatment was performed to analyse possible differences in determination of clinical tooth movements with these methods.

Methods: (1) A hexapod system was used to perform the tooth movements in physical maxillary dental models (N = 70). The initial and final situations were scanned, superimpositions executed, movements calculated, and their accuracy compared to the predefined movements was determined. (2) Digital three-dimensional (3D) maxillary dental models representing pre- and postorthodontic treatment situations (N = 100 patients) were superimposed. Selected tooth movements were calculated (N = 3600), and the results of the different superimposition methods were compared pairwise.

Results: (1) The experimental study delivered only small location and scale shifts. Furthermore, concordance correlation coefficients above 0.99 for all three methods. This verified that all methods deliver values corresponding well to the predefined movements. (2) The retrospective analysis of the clinically performed orthodontic tooth movements comparing pairwise the three different methods intraindividually also showed small location and scale shifts. Furthermore, concordance correlation coefficients between 0.68 and 0.98 were observed, with only three of them below 0.8. This verified that the applied superimposition methods delivered values sufficiently close to each other.

Conclusions: As the experimental study showed very good agreement between the predefined and determined movements, and as the retrospective clinical study showed that the methods compared pairwise delivered values close to each other for the performed orthodontic tooth movements, it can be concluded that orthodontic tooth movements can be determined adequately correct by each of the examined methods.

Purpose: The purpose of this study was to assess differences in the fundamental mechanical properties of resin-made three-dimensional (3D) printed orthodontic aligners according to the printing orientation.

Methods: Twenty resin 3D-printed dumbbell-shaped specimens and 20 orthodontic aligners were fabricated and postcured in nitrogen. Half of the specimens and aligners were built in horizontal (H), the other half in vertical (V) directions. The dumbbell-shaped specimens were loaded in a tensile testing machine, while parts of the aligners were embedded in acrylic resin, ground, polished, and then underwent instrumented indentation testing (IIT). Mechanical properties that were assessed included the yield strength (YS), breaking strength (BS), plastic strain (ε), Martens hardness (HM), indentation modulus (E_IT), elastic index (η_IT), and indentation relaxation (R_IT). Data were analyzed statistically with independent t‑tests or Mann-Whitney tests at α = 5%.

Results: No significant differences were found between specimens or aligners printed either in a horizontal or a vertical direction (P > 0.05 in all instances). Overall, the 3D-printed aligners showed acceptable mechanical propertied in terms of YS (mean 19.2 MPa; standard deviation [SD] 1.7 MPa), BS (mean 19.6 MPa; SD 1.2 MPa), ε (mean 77%; SD 11%), HM (median 89.0 N/mm²; interquartile range [IQR] 84.5-90.0 NN/m²), E_IT (median 2670.5 MPa; IQR 2645.0-2726.0 MPa), η_IT (median 27.5%; IQR 25.9-28.1%), and R_IT (mean 65.1%; SD 3.5%).

Conclusion: Printing direction seemed to have no effect on the mechanical properties of 3D-printed resin aligners, which are promising for orthodontic use.

Objectives: Long-term stabilization of orthodontic treatment outcomes is an everyday challenge in orthodontics. The use of permanently attached lingual retainers has become gold standard. However, in some cases, patients with fixed lingual retainers show retainer-associated side effects. Aiming to reduce these side effects, clinical knowledge about how tooth and arch form stability adaption takes place over time is important to improve long-term retention protocols. Therefore, the present study aimed to investigate occlusion stability and risks for a newly developing malocclusion in a time-dependent manner in patients being treated with permanent 2‑point steel retainers.

Materials and methods: In this retrospective cohort study, a total of 66 consecutive patients with round stainless-steel retainers were analyzed for postorthodontic occlusion changes after 1 year (group 1, n = 33) and 3 years (group 2, n = 33). Digital Standard Tessellation Language (STL) datasets of the lower jaw were obtained before retainer insertion (T0), and after a 1- (T1) or 3‑year (T2) retention period. Using superimposition software, T1 and T2 situations were compared to T0 regarding rotational and translational changes in tooth positions in all three dimensions.

Results: Occlusion changes were low in both groups. The investigated lower canines were nearly stable in the 1‑ and 3‑year group, although a retention-time-dependent increase in tooth position change of the central and lateral incisors could be observed.

Conclusion: The present data provide evidence for time-dependent development of posttherapeutic occlusal adaption limited to central and lateral incisors in patients treated with a 2-point retainer. The observed occlusal changes should be interpreted as an occlusal adaption process rather than severe posttreatment changes associated with the orthodontic retainer.

Purpose: Acidification by bacterial biofilms at the bracket/tooth interface is one of the most common problems in fixed orthodontic treatments, which can lead to white spot lesions (WSL) and caries. As lingual brackets were shown to exhibit reduced WSL formation clinically, the aim of this in situ study was to compare initial intraoral biofilm formation and acidification on bracket-like specimens placed buccally and palatally in the upper jaw as a possible cause for this observation.

Methods: Intraoral biofilm was collected from splints equipped with buccally and palatally exposed test specimens, which were worn by 12 volunteers for a total of 48 h. The test specimens consisted of standard bracket material cylinders on top of a hydroxyapatite disc to represent the bracket/tooth interface. They were analyzed for three-dimensional biofilm volume and live/dead distribution by fluorescence staining and confocal laser scanning microscopy as well as for acidification by fluorescence-based pH ratiometry.

Results: Similar general biofilm morphology with regard to volume and viability could be detected for buccally and palatally exposed specimens. For pH values, biofilms from both positions showed increased acidification at the bottom layer. Interestingly, the pH value at the top layers of the biofilms was slightly lower on palatally than on buccally exposed specimens, which may likely be due to anatomic conditions.

Conclusion: Based on the results of this study, initial intraoral biofilm formation and acidification is almost similar on the bracket material/biomimetic tooth interface when placed buccally or palatally in the upper jaw. As lingual brackets were shown to exhibit reduced WSL formation clinically, future studies should investigate further factors like bracket geometry.