Difference in the alveolar bone remodeling between the adolescents and adults during upper incisor retraction: a retrospective study

Changes in alveolar bone remodeling after maxillary anterior retraction using fixed appliances with different periodontal conditions: A retrospective study based on cone-beam computed tomography

INTRODUCTION

This study aimed to compare changes in maxillary anterior alveolar bone remodeling and complication rates in adult patients with different periodontal conditions after maxillary anterior tooth retraction using fixed appliances. In addition, this study analyzed potential factors affecting alveolar bone thickness in patients with periodontitis.

METHODS

A total of 55 adult patients (mean age, 23.53 ± 4.55 years) with Angle Class I or II Division 1 malocclusion with maxillary protrusion were recruited and categorized into the healthy control group (n = 23), stage I periodontitis (P-I) group (n = 17), and stage II periodontitis (P-II) group (n = 15). The maxillary anterior teeth were retracted using a fixed appliance. Cone-beam computed tomography was used to measure the thickness, height, and density of the alveolar bone in the maxillary anterior region before (T1) and after (T2) treatment. The incidences of bone dehiscence and fenestration were documented. Statistical analysis was conducted to evaluate intergroup and intragroup differences. Clinical and cephalometric data were collected to identify factors affecting the changes in alveolar bone thickness using multivariate linear regression analysis.

RESULTS

The labial alveolar bone thickness increased significantly after treatment in all groups, but no differences were observed among the groups. In contrast, the palatal alveolar bone thickness decreased, particularly in the P-I and P-II groups, at the midroot and apical levels (P <0.05). A significant decrease in alveolar bone height was observed in the P-I and P-II groups (P <0.05). The incidence of palatal bone dehiscence was higher in the P-II (84.44%) and P-I (69.61%) groups. Multivariate linear regression analyses revealed that sex, treatment duration, periodontal treatment, changes in tooth inclination, and initial thickness significantly affected palatal alveolar bone thickness changes in patients with periodontitis.

CONCLUSIONS

After retraction of the maxillary anterior teeth with a fixed appliance, the labial alveolar bone of the maxillary anterior teeth thickened, whereas the palatal bone exhibited thinning in adults with periodontitis. The reduction in palatal bone height was more significant in this population than in healthy subjects, along with a higher incidence of palatal bone dehiscence. Bone morphology must be carefully assessed, considering these relevant factors before and during orthodontic treatment.

Characterization of craniofacial tissue aging in genetically diverse HET3 male mice with longevity treatment of 17-alpha estradiol

OBJECTIVE

The objective of our study was to 1) characterize craniofacial tissue aging in the new, genetically diverse HET3 mouse model; and 2) ascertain whether increased longevity with 17-alpha estradiol (17αE2) treatment in male mice also improved the health of these tissues. The HET3 mice are a four-strain cross preferred and recommended by the National Institute of Aging to identify longevity treatments and test their ability to reduce age-related pathologies. Previous reports demonstrated increased longevity in male, but not female, HET3 mice with 17αE2 administration.

DESIGN

Male mice were raised to approximately 8 months (young), 16 months (middle-aged), and 25 months (old). Middle-aged and old mice were administered a diet supplemented with 17αE2 for 19 weeks. We quantified craniofacial tissue volume and density changes with micro-computed tomography followed by histology.

RESULTS

Micro-CT showed that the alveolar bone volume and density did not change with age or treatment. Enamel volume and density changed with age but not treatment. Histology revealed region-specific degeneration of periodontal ligaments (PDLs) with age. Cellular cementum demonstrated age-related density decreases but no change in volume. However, cementum volume and density increased with 17αE2 treatment. Dentin volume increased with age whereas density decreased with age, which were attenuated by 17αE2 treatment.

CONCLUSIONS

The HET3 mice present an excellent model with which to study the heterogeneous nature of tooth aging and the effects of longevity interventions. We provide novel data on how 17αE2 improves healthspan by modifying age-related changes in the molar dentin and cementum of male mice.

Application of a 3D Fusion Model to Evaluate the Efficacy of Clear Aligner Therapy in Malocclusion Patients: Prospective Observational Study

BACKGROUND

Investigating the safe range of orthodontic tooth movement is essential for maintaining oral and maxillofacial stability posttreatment. Although clear aligners rely on pretreatment digital models, their effect on periodontal hard tissues remains uncertain. By integrating cone beam computed tomography-derived cervical and root data with crown data from digital intraoral scans, a 3D fusion model may enhance precision and safety.

OBJECTIVE

This study aims to construct a 3D fusion model based on artificial intelligence software that matches cone beam computed tomography and intraoral scanning data using the Andrews' Six Element standard. The model will be used to assess the 3D effects of clear aligners on tooth movement, to provide a reference for the design of pretreatment target positions.

METHODS

Between May 2022 and May 2024, a total of 320 patients who completed clear aligner therapy at our institution were screened; 136 patients (aged 13-35 years, fully erupted permanent dentition and periodontal pocket depth <3 mm) met the criteria. Baseline ("simulation") and posttreatment ("fusion") models were compared. Outcomes included upper core discrepancy (UCD), upper incisors anteroposterior discrepancy (UAP), lower Spee curve deep discrepancy (LSD), upper anterior teeth width discrepancy (UAW), upper canine width discrepancy (UCW), upper molar width discrepancy (UMW), and total scores. Subanalyses examined sex, age stage (adolescent vs adult), and treatment method (extraction vs nonextraction).

RESULTS

The study was funded in May 2022, with data collection beginning the same month and continuing until May 2024. Of 320 initial participants, 136 met the inclusion criteria. Data analysis is ongoing, and final results are expected by late 2024. Among the 136 participants, 90 (66%) were female, 46 (34%) were male, 64 (47%) were adolescents, 72 (53%) were adults, 38 (28%) underwent extraction, and 98 (72%) did not. Total scores did not differ significantly by sex (mean difference 0.01, 95% CI -0.13 to 0.15; P=.85), age stage (mean difference 0.03, 95% CI -0.10 to 0.17; P=.60), or treatment method (mean difference 0.07, 95% CI -0.22 to 0.07; P=.32). No significant differences were found in UCD (mean difference 0.001, 95% CI -0.02 to 0.01; P=.90) or UAP (mean difference 0.01, 95% CI -0.03 to 0.00; P=.06) by treatment method. However, adolescents exhibited smaller differences in UCD, UAW, UCW, and UMW yet larger differences in UAP and LSD (df=134; P<.001). Extraction cases showed smaller LSD, UAW, and UCW but larger UMW differences compared with nonextraction (df=134; P<.001).

CONCLUSIONS

The 3D fusion model provides a reliable clinical reference for target position design and treatment outcome evaluation in clear aligner systems. The construction and application of a 3D fusion model in clear aligner orthodontics represent a significant leap forward, offering substantial clinical benefits while establishing a new standard for precision, personalization, and evidence-based treatment planning in the field.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR2400094304, https://www.chictr.org.cn/hvshowproject.html?id=266090&v=1.0.

The periodontal ligament-periosteum sandwich hypothesis: A thought experiment on fenestrations and dehiscences

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.

AL, P. P, R. V, Mahendra J. A review on periodontal care: Challenges among geriatric and pediatric patients

Periodontal care for geriatric and pediatric patients poses distinct challenges due to age-specific factors. In elderly patients, systemic conditions, medications and reduced dexterity complicate treatment. Pediatric patients face unique issues related to developing dentition and behaviour management. This review reports these challenges and offers strategies for effective, tailored periodontal care. Emphasizing patient-centered approaches improves outcomes for both populations.

[Research progress on labial protuberances of anterior teeth in orthodontic treatment]

During orthodontic treatment, irregular and varying sized nodular bony protrusions may sometimes appear on the labial side of the patient's anterior alveolar bone, which is closely related to the differential bone remodeling on the inner and outer surfaces of the alveolar bone. Labial protuberances not only affect the aesthetic results of orthodontic treatment, but also pose potential risks to periodontal health. Currently, it is believed that the influencing factors of the formation of the labial protuberances may be related to the patient's gender and age, tooth movement speed, and extent of anterior teeth retraction. Labial protuberances typically resolve spontaneously, however, if persistent, alveoloplasty may be necessary for treatment. This review provides a summary on the occurrence, influencing factors of formation, potential biological mechanisms, and corresponding treatment methods of labial protuberances during orthodontic treatment.

Age-related alveolar bone maladaptation in adult orthodontics: finding new ways out

Compared with teenage patients, adult patients generally show a slower rate of tooth movement and more pronounced alveolar bone loss during orthodontic treatment, indicating the maladaptation of alveolar bone homeostasis under orthodontic force. However, this phenomenon is not well-elucidated to date, leading to increased treatment difficulties and unsatisfactory treatment outcomes in adult orthodontics. Aiming to provide a comprehensive knowledge and further inspire insightful understanding towards this issue, this review summarizes the current evidence and underlying mechanisms. The age-related abatements in mechanosensing and mechanotransduction in adult cells and periodontal tissue may contribute to retarded and unbalanced bone metabolism, thus hindering alveolar bone reconstruction during orthodontic treatment. To this end, periodontal surgery, physical and chemical cues are being developed to reactivate or rejuvenate the aging periodontium and restore the dynamic equilibrium of orthodontic-mediated alveolar bone metabolism. We anticipate that this review will present a general overview of the role that aging plays in orthodontic alveolar bone metabolism and shed new light on the prospective ways out of the impasse.

Alveolar bone remodelling and stability of mandibular incisors in adult patients after orthodontic treatment with premolar extractions: A prospective follow-up study

OBJECTIVE

To evaluate alveolar bone remodelling and stability of mandibular incisors in adult orthodontic extraction patients.

MATERIALS AND METHODS

Cone-beam computed tomography images of 25 adult patients undergoing extraction were collected before orthodontic treatment (T1), after orthodontic treatment (T2), and after at least 1 year of retention (T3). The labial and lingual alveolar bone heights (ABH), thickness (ABT), and tooth movement of the mandibular incisors were measured during the retraction (T2-T1) and retention (T3-T2) periods. According to the tooth movement during the retention period, the mandibular incisors were further divided into stable and unstable groups, and the correlation between L1-BMe and stability was evaluated.

RESULTS

The labial and lingual ABHs significantly increased after orthodontic treatment and decreased during the retention period. The lingual ABH was 7.36 ± 2.27 mm at T2 and 5.37 ± 1.98 mm at T3, indicating a great bone remodelling capacity. The labial ABT exhibited a significant increase during orthodontic treatment and a slight decrease during the retention period, while the lingual ABT showed an opposite trend. During the retention period, the root apex moved labially into the alveolar bone housing. L1-BMe significantly increased during orthodontic treatment and decreased during the retention period. Compared to the stable group, lingual ABH and L1-BMe at T2 was significantly higher, and lingual ABT was smaller in the unstable group.

CONCLUSION

Post-treatment lingual alveolar bone defects of the mandibular incisors could recover to some extent during the retention period. There was a negative correlation between post-treatment L1-BMe and mandibular incisor stability.

Combined distalization and lingual cortex remodeling during mandibular growth for facial profile improvement: a case report

Borderline crowding poses a challenge in deciding whether or not to prescribe premolar extraction. This case report describes the two-phase nonextraction orthodontic treatment of an 11-year-old girl with a hyperdivergent skeletal Class I pattern exhibiting anterior crowding and moderate lip protrusion. The initial phase of treatment included maxillary and mandibular expansion to correct the transverse discrepancy as an early intervention. Subsequently, comprehensive treatment was initiated at the age of 13 years, with fully erupted permanent second molars and growth potential remaining. Phase II treatment involved a second round of maxillary expansion, followed by simultaneous bimaxillary total arch intrusive distalization, using interradicular, temporary skeletal anchorage devices to correct dental crowding and improve the facial profile. Although the limited retromolar space posed a challenge to mandibular tooth distalization, gradual bone remodeling was observed in the lingual cortex of the mandibular body, enabling sufficient orthodontic tooth movement without noticeable side effects. After 4 years 3 months of treatment, her dental crowding was relieved, with significant improvement in the facial profile and proper occlusion. The treatment outcomes remained stable 2 years 4 months after retention.

Low-intensity pulsed ultrasound reduces alveolar bone resorption during orthodontic treatment via Lamin A/C-Yes-associated protein axis in stem cells

BACKGROUND

The bone remodeling during orthodontic treatment for malocclusion often requires a long duration of around two to three years, which also may lead to some complications such as alveolar bone resorption or tooth root resorption. Low-intensity pulsed ultrasound (LIPUS), a noninvasive physical therapy, has been shown to promote bone fracture healing. It is also reported that LIPUS could reduce the duration of orthodontic treatment; however, how LIPUS regulates the bone metabolism during the orthodontic treatment process is still unclear.

AIM

To investigate the effects of LIPUS on bone remodeling in an orthodontic tooth movement (OTM) model and explore the underlying mechanisms.

METHODS

A rat model of OTM was established, and alveolar bone remodeling and tooth movement rate were evaluated via micro-computed tomography and staining of tissue sections. In vitro, human bone marrow mesenchymal stem cells (hBMSCs) were isolated to detect their osteogenic differentiation potential under compression and LIPUS stimulation by quantitative reverse transcription-polymerase chain reaction, Western blot, alkaline phosphatase (ALP) staining, and Alizarin red staining. The expression of Yes-associated protein (YAP1), the actin cytoskeleton, and the Lamin A/C nucleoskeleton were detected with or without YAP1 small interfering RNA (siRNA) application via immunofluorescence.

RESULTS

The force treatment inhibited the osteogenic differentiation potential of hBMSCs; moreover, the expression of osteogenesis markers, such as type 1 collagen (COL1), runt-related transcription factor 2, ALP, and osteocalcin (OCN), decreased. LIPUS could rescue the osteogenic differentiation of hBMSCs with increased expression of osteogenic marker inhibited by force. Mechanically, the expression of LaminA/C, F-actin, and YAP1 was downregulated after force treatment, which could be rescued by LIPUS. Moreover, the osteogenic differentiation of hBMSCs increased by LIPUS could be attenuated by YAP siRNA treatment. Consistently, LIPUS increased alveolar bone density and decreased vertical bone absorption in vivo. The decreased expression of COL1, OCN, and YAP1 on the compression side of the alveolar bone was partially rescued by LIPUS.

CONCLUSION

LIPUS can accelerate tooth movement and reduce alveolar bone resorption by modulating the cytoskeleton-Lamin A/C-YAP axis, which may be a promising strategy to reduce the orthodontic treatment process.

Bone Remodeling of Maxilla after Retraction of Incisors during Orthodontic Treatment with Extraction of Premolars Based on CBCT Study: A Systematic Review

Background: Incisor retraction is often a crucial phase in ongoing orthodontic treatment, with significant implications for alveolar remodeling mechanisms. There are two prevailing theories which seek to explain this. According to the first, teeth move with the bone, while according to the second, teeth move within the bone. This systematic review seeks to assess morphometric changes in the maxillary alveolar process resulting from incisor retraction following premolar extraction and to evaluate the potential for bone remodeling associated with orthodontic movement. Methods: The study was conducted following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. The following electronic databases were searched: PubMed, Google Scholar, Web of Science EMBASE and the Cochrane Central Register of Controlled Trials. The databases were searched using the following keywords: "Bone remodeling and retraction of incisors", "Alveolar bone and incisor retraction", "Bone thickness and incisor retraction", and "Bone changes and orthodontic treatment". Search filters were utilized to identify relevant papers and articles written in English and published during the last 10 years. Based on the information provided in their abstracts, papers and articles were selected according to the following criteria: randomized clinical trials (RCTs), controlled clinical prospective trials (CCTs), and retrospective studies. Articles unrelated to the study's scope or failing to meet inclusion criteria were excluded. These generally comprised individual case reports, case series reports, literature reviews, experimental studies, studies with limited data (including conference abstracts and journal writings), studies involving an unrepresentative group of patients (less than 10 patients), studies concerning patients with syndromes, and animal experiments. The remaining articles which were deemed relevant underwent comprehensive reference review and such journals as the American Journal of Orthodontics, Dentofacial Orthopedics, International Orthodontics, Journal of Clinical Orthodontics, and Angle Orthodontist were manually searched. Results: Seven articles meeting the inclusion criteria articles were selected for final evaluation, with a total of 284 participants, including 233 women and 51 men. During the analysis of the results included in the publications, a lack of homogeneity was observed, rendering a reliable statistical analysis and heterogeneity assessment unobtainable. Noteworthy disparities in methodologies and measurements posed a risk of drawing inappropriate conclusions. Consequently, emphasis was placed on qualitative analysis, emphasizing the need for standardization in future studies of a similar nature, to enable valid and comparable analyses. Conclusions: The research findings incorporated in this review demonstrate that significant bone loss occurs because of incisor retraction, which diminishes distance between the bone surface and the root surface on the palatal aspect. The magnitude of this change may vary, contingent upon both the extent of incisor displacement and alterations in their inclination, thereby affecting the positioning of the root tips. This change is significantly higher in adults than in growing adolescents. The rationale behind this assertion lies in the widely recognized phenomenon of declining cellular activity with advancing age. The decrease in the speed and intensity of cellular changes may explain the diminished capacity for remodeling as patient age increases. There is ongoing discourse regarding alterations in the volume of bone on the labial aspect of the alveolar process. Further research is necessary to measure whether bone remodeling during orthodontic movement is contingent upon other factors, such as the speed and biomechanics of retraction, the level of applied orthodontic force, and the patient age.

Comparative analysis of anchorage strength and histomorphometric changes after implantation of miniscrews in adults and adolescents: an experimental study in Beagles

OBJECTIVES

This study aimed to explore the differences in anchorage strength and histomorphometric changes in orthodontic miniscrews between adult and adolescent beagles.

MATERIAL AND METHOD

Six adult beagles and six young beagles were used as experimental subjects, and eight miniscrews were symmetrically placed in the posterior mandible of each dog. Measurement of the displacement (mm) of two adjacent miniscrews after load application was performed to compare the anchorage strength between the adult and adolescent groups. Three intravital bone fluorochromes (oxytetracycline, calcein green, xylenol orange) were administered postoperatively to mark the active bone-forming surface. Subsequently, the mineral apposition rate and bone-implant contact ratio were measured for dynamic and static histomorphometry. Finally, the expression levels of the RANKL/OPG ratio were evaluated by immunohistochemistry.

RESULTS

The average displacement of miniscrews in the adult group was significantly less than that in the adolescent group after load application. For histomorphometry analysis, the mineral exposure rate in the adolescent group was higher than that in the adult group with or without force application. In addition, more fractures and new bone formation but deceased bone-implant contact ratios were observed in the adolescent group than in the adult group. The ratio of RANKL/OPG expression increased more in the adolescent group than in the adult group.

CONCLUSION

Miniscrews do not remain in the same position as skeletal anchors, and the amount of displacement was higher in adolescent group than that in adult group, reflecting the weaker anchorage strength of miniscrews in adolescents due to the higher bone turnover rate and active bone remodelling. Therefore, it is feasible to apply orthodontic loading to the miniscrews in adult patients earlier, even immediately, but it is recommended to wait a period for the adolescents.

Evaluation of alveolar bone morphology of incisors with different sagittal skeletal facial types by cone beam computed tomography: A retrospective study

Background

Safe orthodontic tooth movement should be performed within the alveolar bone. The purpose of this study was to evaluate the morphology of the alveolar bone of incisors.

Materials and methods

This retrospective study included pretreatment cone beam computed tomography of 120 patients with malocclusion. Patients were divided into 4 groups (Class I, Class II division 1, Class II division 2 and Class III) according to the subspinale-nasion-supramental (ANB) angle and occlusal relationship. The sagittal root positions, anterior and posterior root-cortical bone angles (AR-CA and PR-CA), root-crown ratios (RCR) and alveolar bone thickness were evaluated.

Results

The sagittal root positions were mainly positioned against the labial cortical plate in the maxillary incisors of the Class II division 2 group and engaged by both the labial and palatal cortical plates in the mandibular incisors of the Class III group. The AR-CA was lower than that in the other groups (P < 0.01) in the maxillary incisors of the Class II division 2 group, and the AR-CA and PR-CA were lower than those in the other groups (P < 0.01) in the mandibular incisors of the Class III group. The alveolar thickness showed no significant difference between the Class II division 1 group and the Class I group (P > 0.05), the middle and lower anterior alveolar thickness (LAAT and MAAT) were lower than those in other groups (P < 0.01) in the maxillary incisors of the Class II division 2 group, and the alveolar thickness at the measurement sites of the middle and lower line were lower than those in other groups (P < 0.01) in the mandibular incisors of the Class III group. The RCR had a moderate positive correlation with the LAAT.

Conclusion

Based on several limitations, this study found that maxillary incisor roots were at risk of penetrating the alveolar bone of Class II division 2 patients, and mandibular incisors may have a relatively small range of safe movement on both the labial and lingual sides of Class III patients during orthodontic treatment.

Detailed Correlation between Central Incisor Movement and Alveolar Bone Resorption in Adults with Orthodontic Premolar Extraction Treatment: A Retrospective Cohort CBCT Study

Background: This study aims to explore the detailed correlation between the movement of maxillary and mandibular central incisors and alveolar bone resorption in adults who had orthodontic premolar extraction treatment. Methods: A total of 63 adult patients (mean age, 24.41 years) who received orthodontic treatment with the extraction of four first premolars were included in this study. CBCT images were obtained before and after treatment. Three-dimensional evaluations of the movement of 252 central incisors (126 maxillary and 126 mandibular incisors) and alveolar bone changes were conducted. Four points were used to describe the incisor movement: C (cusp point), R (root apex point), M (mid-point of root neck), and L (labial cementoenamel junction point). The thickness of labial and palatal alveolar bone was assessed at the crestal, mid-root, and apical levels of incisors. The results were analyzed with Spearman’s correlation and multilinear regression. Results: Matching the measurements of central incisor movement and alveolar bone resorption, significant correlations could be observed. For maxillary central incisors, the labial alveolar bone resorption at the crestal level was correlated with the movement of Point L (r = 0.290, p < 0.05), and the labial alveolar bone resorption at the apical level was correlated with Point M (r = 0.387, p < 0.05). For mandibular central incisors, the labial alveolar bone resorption at the apical level was correlated with the movement of Point M (r = 0.493, p < 0.05) and R (r = 0.498, p < 0.01); the palatal alveolar bone resorption at the mid-root level with Point M (r = -0.170, p < 0.01); and the palatal alveolar bone resorption at the apical level with Point R (r = 0.177, p < 0.01). Conclusions: This study investigated the concrete correlations between central incisor movement and alveolar bone resorption in adults after orthodontic treatment with premolar extraction. It is potentially helpful for orthodontists to have a relatively accurate prediction of alveolar bone resorption based on the specific movements of central incisors and to reduce the risk of alveolar bone resorption by better adjusting the three-dimensional movement types of incisors.