Progress in Orthodontics最新文献

Background: Tooth wear is an important mechanism for reducing dental dimensions and, consequently, dental crowding. The objective of this cohort study was to examine the relation of tooth wear, adjusted for covariates (age, tooth loss, arch perimeter and intercanine width), on tertiary crowding in Amazon Indigenous populations.

Methods: A sample of 40 Indigenous people in permanent dentition at T0 (baseline) and after 13 years (T1) were evaluated. The sample included 16 males and 24 females belonging to two villages, Arara (n = 22, mean ages 16.6 and 29.9 years) and Assurini do Xingu (n = 18, mean ages 16.0 and 29.6 years). Clinical, intraoral photograph and dental cast evaluations were performed at both times. The anterior crowding was measured using Little's Irregularity Index (LI) and modeled through a multilevel linear regression with the predictor variables: village, tooth wear (T1-T0), age (T0), tooth loss (T1-T0), changes in intercanine width (T1-T0) and changes in arch perimeter (T1-T0).

Results: A slight increase was observed (< 1 mm) in anterior dental crowding and a decrease in arch perimeter < 1.5 mm, while tooth wear increased between 0.65 and 0.99 units. The contextual variable (village) had no significant association with LI. In the upper arch, tooth loss was the only variable that showed an inverse association with LI (β=-0.41, p < 0.05). In the lower arch, the increase in dental crowding was inversely associated with tooth wear (β=-1.30, p < 0.05) and changes in arch perimeter (β=-0.31, p < 0.05). The other variables did not show significant associations.

Conclusion: After 13 years, dental crowding and tooth wear increased, while the arch dimensions tended to decrease. The changes in long-term dental crowding seem to have distinct etiological components for each dental arch. In the mandible, the changes in incisor alignment were associated with increased tooth wear and decreased dental arch dimensions. Whereas in the maxilla, only tooth loss caused alterations in tooth alignment. It is suggested that the effect of increased tooth wear on the etiology of tertiary crowding is of small magnitude and restricted to the lower dental arch.

Background: Yes-associated protein (YAP) is a crucial mechanosensor involved in mechanotransduction, but its role in regulating mechanical force-induced bone remodeling during orthodontic tooth movement (OTM) is unclear. This study aims to elucidate the relationship between mechanotransduction and mechanical force-induced alveolar bone remodeling during OTM.

Results: Our study confirms an asynchronous (temporal and spatial sequence) remodeling pattern of the alveolar bone under mechanical force during OTM. Both compression and tension activate osteoclasts recruiting to the alveolar bone, whereas no significant presence of osteoblasts in the alveolar bone at the early stages of bone remodeling. Specifically, applying different force magnitudes (10, 25, 50, 100 g) to rats' 1st molars affected OTM distance. Force-induced alveolar bone remodeling was characterized by osteoclastogenesis and YAP activation at compressive/tensile sites on day 1 of OTM. Notably, 25 g force triggered peak YAP expression and osteoclastic activity early on. Time-course analysis revealed two YAP activity peaks on day1 and 14, contrasting with one peak of type I collagen expression on day14. In addition, RNA-sequencing highlighted increased nuclear factor kappa B (NF-κB) signaling, mineral absorption, and osteoclast differentiation at day-1 and 3. Moreover, gene expression analysis showed similar trends for NF-κB p65, YAP1, and TEA domain 1 (TEAD1) during this time. Furthermore, experiments on osteoclast cultures indicated YAP activation via large tumor suppressor (LATS) and TEAD under mechanical stimuli (compression/tension), promoting osteoclastogenesis by regulating NF-κB p65 and receptor activator of NF-κB (RANK). Inhibiting YAP with verteporfin delayed OTM by impairing force-induced osteoclastic activities in vivo and ex-vivo.

Conclusions: We propose that YAP mediates alveolar bone remodeling through NF-κB p65-induced osteoclastogenesis in an asynchronous remodeling pattern during OTM. Both compression and tension activate osteoclasts recruiting to the alveolar bone at early stages of bone remodeling, offering evidence for orthodontists as a reference.

Background: White spot lesions (WSLs) may develop in adolescents undergoing clear aligner (CA) therapy with poor oral hygiene. The specific effects of CAs on the microbial composition and functional characteristics of supragingival plaques remain unclear. The present study investigated the shift in the supragingival microbial community induced by CAs in adolescents through metagenomic technology.

Methods: Fifteen adolescents (12-15 years old) with Invisalign appliances were recruited. Supragingival plaque specimens were obtained twice, before treatment (T₁) and three months after treatment (T₂). All the bacterial plaque specimens were analyzed for microbial communities and functions using metagenomic analyses.

Results: A total of 2,840,242,722 reads disclosed 180 phyla, 3,975 genera, and 16,497 microbiome species. During the first three months, the microbial community was relatively stable. The genus level revealed a higher relative abundance of Capnocytophaga, Neisseria, and Arachnia in the T₂ period. Furthermore, the functional analysis suggested that the relative abundances of folate biosynthesis, biotin metabolism and biofilm formation-vibrio cholerae were increased in the T₂ period compared to the T₁ period. Finally, virulence factor analysis demonstrated that the relative abundance of genes associated with type IV pili (VF0082) and polar flagella (VF0473) was higher in the T₂ period than in the T₁ period.

Conclusion: In adolescents undergoing CA therapy with poor plaque control, caries progresses quickly within three months and noticeable WSLs develop on the tooth surface. Although the microbial community remained relatively steady and CA therapy did not cause significant changes in the overall functional gene composition in the first three months, virulence factors, including type IV pili and flagella, were more abundant and actively contributed to microorganism adhesion and biofilm formation.

Background: This study aimed to analyze the effects of maxillary molar distalization using clear aligners with different intramaxillary and intermaxillary traction via the three-dimensional (3D) finite element method.

Methods: A 3D finite element model consisting of the maxilla, mandible, dentitions, periodontal ligaments (PDLs), attachments, and clear aligners was constructed. Five groups were established based on different traction modalities: group 1 (control group); group 2 (orthodontic mini-implants (OMIs) were implanted between the maxillary first molars and the second premolars on the buccal side); group 3 (OMIs were implanted in the infrazygomatic crest area between the maxillary first and second molars on the buccal side); group 4 (OMIs were implanted between the maxillary first molars and the second premolars on the palatal side); and group 5 (class II elastics were utilized between the maxillary canines and the mandibular first molars). OMIs were implanted 4 mm away from the alveolar crest in each experimental group. A force of 1.5 N was applied to each experimental group. The 3D displacement of the target teeth and stress distribution around the PDLs were analyzed.

Results: Group 4 exhibited the least amount of torque change in the upper anterior teeth and the highest displacement of the maxillary second molars. Group 3 showed smaller changes in anterior teeth torque and higher molar distalization efficiency compared to group 2. Group 5 showed adverse effects such as anterior teeth extrusion and mandibular anchorage loss.

Conclusion: OMIs implanted on the palatal side have advantages in preserving anterior teeth anchorage and improving the efficiency of molar distalization compared to those positioned on the buccal side. OMIs implanted in the infrazygomatic crest area between the first and second molars on the buccal side demonstrate benefits in the aforementioned aspects when compared to OMIs implanted between the first molars and the second premolars on the buccal side.

Background: Molar distalization with clear aligners (CAs) is a common treatment. However, when the molars reach their target position and the distal movement of premolars begins, the mesial movement of molars might reduce the overall efficiency of molar distalization. This study aimed to investigate tooth movement patterns under different CA designs in the premolar distalization stage using a four-dimensional mechanical simulation method.

Methods: A finite element method (FEM) model encompassing the maxillary dentition, periodontal ligaments, attachments, and associated CAs was constructed. The simulation aimed to replicate a premolar distalization of 2 mm within 10 sequential steps. Buccal interradicular mini-implants were used. Three groups of CAs were designed: the conventional CA design group (Con group), the second molar half-wrap group (SMHW group) and the all-molar half-wrap group (MHW group). An iterative computational approach was employed to simulate prolonged tooth movement resulting from orthodontic forces. Additionally, morphological alterations in the CA throughout the staging process were simulated utilizing the thermal expansion method.

Results: Compared with the Con and SMHW groups, the MHW group presented significantly reduced mesial movement of the first and second molars. However, the MHW group presented the greatest displacement of canines and incisors. The distalization efficiency of premolars in the MHW group reached 95.5-96.5%, which was substantially greater than that in the Con group (84.5-85%) and the SMHW group (75-75.5%).

Conclusions: The four-dimensional mechanical simulation results indicate that during the process of premolar distalization with CA, removing the distal portion of the aligner covering the first and second molars (MHW group) can effectively reduce the mesial movement of molars. Consequently, this approach can increase the overall efficiency of molar distalization.

Background: This study aimed to evaluate the effect of systemically administered anti-sclerostin antibodies (Anti-Scl Ab) on orthodontic tooth movements (OTM) in an ovariectomized rat.

Methods: Twenty-four 12-week-old female Sprague-Dawley rats were randomly divided into two groups: (1) ovariectomy (OVX) group, (2) ovariectomy + romosozumab (ROMO) group. OTM was performed 8 weeks after OVX. The ROMO group received subcutaneous injections of romosozumab twice a week, starting two weeks after OVX. Eight weeks after the OVX, an orthodontic force of 50 g was measured and applied by connecting orthodontic elastic bands between the maxillary first molar and a mini-screw to facilitate tooth movement (orthodontic treatment). Subsequently, the three rats were sacrificed on days 5, 7, 10, and 14. The plaster models were scanned to measure the amount of tooth movement. The effects on alveolar bone and periodontal tissues were evaluated through micro-computed tomography (micro-CT) analysis, tartrate-resistant acid phosphatase (TRAP) staining, and immunohistochemistry (IHC) analysis.

Results: The ROMO group showed more tooth movement on day 7 of orthodontic treatment. Conversely, on days 10 and 14, relatively less movement was observed. Analysis of the root furcation area of the maxillary first molars revealed that from the 7th day, BV/TV, Tb.N., Tb.Th. increased, while Tb.Sp. decreased in the ROMO group. More TRAP-positive cells were observed in the compression side of the OVX group, the ROMO group exhibited a marked decrease in the positive expression of the RANKL, OPG, and sclerostin. The OPG/RANKL ratio showed significant differences in expression between the two groups. The ROMO group exhibited a higher OPG/RANKL ratio than the OVX group, and the tension side exhibited a higher OPG/RANKL ratio demonstrating significant differences.

Conclusion: Romosozumab initially accelerated tooth movements, but later decreased tooth movement. As new alveolar bone is formed, the micro-CT parameters are also improved. Osteoclasts, RANKL, OPG, and sclerostin decreased, while the OPG/RANKL ratio became higher.

Introduction: Although with increasing popularity due to aesthetic appeal and comfort, clear aligners (CAs) are facing challenges in efficacy and predictability. Advancement in the underlying biomechanical field is crucial to addressing these challenges. This paper endeavors to provide a comprehensive framework for understanding the biomechanics of CA and enlightening biomechanics-based improvements on treatment strategies.

Methods: A thorough review of the English-language literature accessible through PubMed and Google Scholar, without any publication year restrictions, was undertaken to unravel the biomechanical aspects of CA.

Results: This review presented an up-to-date understanding of aligner biomechanics arranged by the framework of the material-dependent mechanical characteristics of CA, the geometric characteristics-dependent force transmission of the CA system, methods for studying the biomechanics of CA, and the biomechanical analyses for different types of tooth movement.

Conclusions: Biomechanics should be the fundamental concern for concepts, methods and adjuncts attempting to enhance the accuracy and predictability of tooth movement induced by CA. Improvement on material properties and alteration of geometric design of CA are two main approaches to develop biomechanically optimized force system. Exploration of real-world force sensing and monitoring system would make substantial progresses in aligner biomechanics.

Objective: This study compared the achieved tooth movement to that predicted in the preliminary simulated digital treatment plan between adults and teenagers.

Materials and methods: Records of 60 patients (30 adults; mean age: 36.6 ± 11.36 years, and 30 teenagers; mean age: 16.23 ± 2.25 years) were randomly selected. Initial and predicted models were obtained from the initial simulated treatment plan. The first model of the refinement scan was labeled as achieved. SlicerCMF software (version 3.1; https://www.slicer.org ) was used to superimpose the achieved and predicted digital models over the initial ones with regional superimposition on relatively stable first molars. 600 teeth were measured in each group for horizontal, vertical, angular movements, and transverse dimensions. Accuracy was defined as the achieved amount of movement minus predicted and was calculated for each individual and compared between teens and adults.

Results: The mandibular inter-canine width accuracy was statistically significant between groups (p = 0.050). Significant under-correction in horizontal movements was noted for mandibular first premolars in teenagers compared to adults (p = 0.037). There was considerable over-correction in horizontal movements for mandibular central and lateral incisors between groups (p < 0.05). No significant difference was observed between groups in the vertical plane. Rotations were underachieved for maxillary first premolars, more in adults than teenagers (p = 0.017).

Conclusion: The accuracy of achieved versus predicted tooth movement between adults and teenagers was significant for the inter-canine width. Mandibular central and lateral incisors showed significantly greater over-correction in adults in the horizontal plane. The accuracy of rotations and vertical movements was comparable.

Background: Obstructive sleep apnea (OSA) is a complex disorder characterized by interruptions in breathing during sleep, leading to a range of adverse outcomes from reduced quality of life to serious health risks, including cardiovascular diseases and increased mortality.

Main body: This manuscript reviews the orthodontists' essential role in the multidisciplinary healthcare team tasked with managing OSA. It particularly highlights critical orthodontic interventions, such as surgical-orthodontic maxillomandibular advancement (MMA), mandibular advancement appliances (MAAs), and rapid maxillary expansion (RME). These interventions are pivotal in modifying craniofacial structures to enhance airway patency. The importance of conducting a thorough airway analysis is underscored, assessing the complete anatomical and functional factors contributing to airway obstruction.

Conclusion: The paper calls for increased collaborative research efforts to develop standardized, evidence-based orthodontic procedures for effectively managing OSA, aiming to improve patient outcomes through specialized, tailored interventions.