Biomechanics of conventional and miniscrew-assisted rapid palatal expansion.

Posterior Crossbite is a common condition resulting because of transverse maxillary deficiency. The growth of the craniofacial complex finishes first in the transverse dimension, followed by sagittal and vertical dimensions. Conventional rapid palatal expansion (RPE) appliances are commonly used to correct transverse maxillary deficiency. Although RPE is efficient in correcting posterior crossbite, it results in dental side effects such as buccal tipping of maxillary molars, root resorption, bone dehiscence, and relapse. Mini-implant-assisted RPE has been introduced to increase the skeletal effects of expansion especially in patients with increased maturation and greater interdigitation of midpalatal suture. This article will review the biomechanics of RPE and mini-implant-assisted RPE. Additionally, the different designs of MARPE and the long-term clinical effects of expansion appliances will also be discussed in detail.

2023-2024 American Board of Orthodontics practice analysis study: Part 1.

As a specialty board, the American Board of Orthodontics (ABO) serves to protect the public and the orthodontic specialty by certifying orthodontists. The demonstration of commitment to lifelong learning and self-improvement is critical to achieving the highest level of patient care. The ABO completed a practice analysis study in 2023 to ensure all examinations represent current assessments of proficiency in orthodontics at a level of quality that satisfies professional expectations. The practice analysis is essential to providing a demonstrable relationship between the examination content and orthodontic practice and provides a critical foundation for ABO's examination programs.

Long-term evaluation of soft-tissue changes after miniscrew-assisted and conventional rapid palatal expansion using voxel-based superimposition of cone-beam computed tomography scans.

INTRODUCTION: This study aimed to evaluate the soft-tissue changes in the long-term after miniscrew-assisted rapid palatal expansion (MARPE) and conventional rapid palatal expansion (RPE) appliances compared with a matched control group using voxel-based superimposition of cone-beam computed tomography (CBCT) scans. METHODS: A total of 180 CBCTs for 60 patients at 3-time points were evaluated: pretreatment (T1), postexpansion (T2), and posttreatment (T3) for 3 groups: (1) MARPE, (2) RPE, and (3) controls (time-period T1 to T3: MARPE, 2 years 8 months; RPE, 2 years 9 months; control, 2 years 7 months). The voxel-based superimposition technique was used to superimpose the CBCT scans, after which the soft-tissue surfaces were extracted from the superimposed T1-CBCT, T2-CBCT, and T3-CBCT scans. Nine landmarks were identified on the CBCT scans: nasion, A-point, pogonion, right and left alar base, right and left zygoma, and right and left gonion. The coordinates of the 9 parameters were obtained in the x-axis, y-axis, and z-axis for the CBCT scans and subjected to statistical analyses. The changes in the soft-tissue surfaces were also evaluated by color-coded maps for short-term (T2) and long-term (T3) changes. The mean changes from T1 to T2 and T1 to T3 were tested against no change within the groups by paired t test, and the mean changes among the 3 groups were compared with analysis of variance F test with Tukey's Honest significant difference used for adjusting P values for multiple testing. RESULTS: In the short term, both MARPE and RPE led to a significant downward movement of pogonion, left gonion, and lateral movement of the right and left alar base compared with controls at T2 (P <0.05). In addition, MARPE led to a significant downward movement of right gonion than controls at T2 (P <0.05). Moreover, RPE led to a significant downward and forward movement of A-point and downward movement of the right and left alar base than controls at T2 (P <0.05). However, in the long-term, there were no significant differences in the soft-tissue changes among the MARPE, RPE, and control groups. CONCLUSIONS: MARPE and RPE do not lead to significant soft-tissue changes in the long term when compared with controls.

Estimating the 3-D location of impacted maxillary canines: A CBCT-based analysis of severity of impaction.

OBJECTIVES: The objective of the study was to quantify the 3-D location of impacted canines by measuring their linear and angular deviations in relation to adjacent structures and further evaluate impaction severity. METHODS: CBCT images of 314 impacted canines were analysed in the sagittal, coronal and axial planes. Linear and angular measurements were recorded. Canine inclination was identified in coronal and sagittal planes. An evaluation system was constructed for analysis. Upright canine was considered as the appropriate position for fully erupted maxillary canine. Outcomes were compared between right and left sides and by gender. For categorical variables, chi-square tests were used while Mann-Whitney U test was used for continuous variables. Regression models were used to measure severity. RESULTS: Impactions were greater in females (119/207; 57.5%). No significant differences between unilateral (100/207; 49.3%) and bilateral (107/207; 51.7%) (P > 0.05). Out of 314 impactions, 105 (33.4%) were mild, 118 (37.58%) moderate and 91 (28.98%) severe. Severe impactions were primarily buccal (44/ 91; 48.3%), in the occlusal ½ of the adjacent incisor root (38/ 91, 41.7%), mesial to the distal border of central incisor (47/91, 51.6%), with sagittal angle value + >45 ̊ (46/ 91, 50.5%) and mesial tip + >30 ̊ (86/ 91, 94.5%). CONCLUSIONS: Severely impacted canines had their crowns buccal, closer to occlusal plane and mesial to the distal border of the central incisor with greater than 45-degree buccal inclination and greater than 30-degree mesial tip. The sagittal angle can have a significant impact on the severity of impaction. A new classification system was proposed to quantify severity.

Orthodontic and surgical management of a patient with severe mandibular deficiency and asymmetry with condylar hypoplasia using 3-dimensional surgical planning in combination with a modified surgery-first approach.

Progressive improvements in digital technology and surgical techniques have synergized the speed, predictability, and favorable outcomes for patients undergoing surgical-orthodontic treatment with handicapping dentofacial deformities. This case report will demonstrate the management of a patient with severe mandibular hypoplasia, condylar hypoplasia, and mandibular asymmetry. The dentofacial deformity, and consequently, the unaesthetic facial appearance, led to psychosocial stress, symptoms of excessive daytime sleepiness, and functional limitations, especially related to mandibular movements. A modified surgery-first approach was used, which was successfully performed using computer-assisted surgical planning. Postsurgical orthodontics was accomplished with the aid of temporary skeletal anchorage mini-plates. An additional alloplastic enhancement of the chin addressed the severe microgenia, which the osseous advancement could not achieve. This resulted in a total advancement of the pogonion by 26 mm yielding a remarkable improvement in the patient's facial esthetics. Furthermore, a considerable improvement in mandibular function and reduction in daytime sleepiness occurred. The severe malocclusion with a discrepancy index value of 47 was treated to a successful final occlusion in 21 months of treatment time.

Orthodontic management of a patient with short root anomaly and impacted teeth.

Short root anomaly (SRA) is a rare familial dental condition that is often misdiagnosed. Orthodontic treatment of patients with SRA is challenging because it is difficult to diagnose, it may be accompanied by other dental anomalies, and it has been reported to contribute to additional susceptibility to root resorption during orthodontic treatment. In this article, we describe a methodical and evidence-based means of diagnosing and orthodontically managing a patient with SRA. The patient had additional challenges, including impacted and ectopic teeth. An individualized treatment plan that incorporated efficient and effective mechanics led to a well seated occlusion and an esthetic smile.

Gender and growth variation in palatal bone thickness and density for mini-implant placement.

BACKGROUND: The objective was to compare the palatal bone thickness (PBT) and palatal bone density (PBD) in the anterior, middle, and posterior part of the palate in males and females. METHODS: This retrospective study reviewed cone beam computed tomography scans of 359 patients. The scans were divided into 99 growing males, 105 growing females, 74 non-growing males, and 81 non-growing females. The measurements of PBT and PBD were made in between the canine and first premolar, the first premolar and second premolar, the second premolar and first molar, and the first molar and second molar. The measurements were made in the center of the palate and 4 mm away from the center. ANOVA was used to analyze the PBT and PBD in different areas between four different groups. RESULTS: The PBT was lower (P <  0.0001) as we moved from the anterior to the posterior palate. The PBT was more (P <  0.001) in the center of the palate than 4 mm away from the center, except in between the canine and first premolar. The growing male and non-growing male had higher (P <  0.0001) PBT than the growing female and non-growing female in between the canine and first premolar and the first premolar and second premolar both in the center and 4 mm away from it. The PBD was higher (P <  0.05) in between the canine and first premolar area at the center of the palate and between the second premolar and first molar 4 mm away from the center in all the experimental groups. CONCLUSIONS: There exists a definite gender and growth variation in the PBT and PBD in different parts of the palate. Palatal bone thickness between the males and females revealed that the males had significantly higher PBT than the females.

Force System with Vertical V-Bends: A 3D In Vitro Assessment of Elastic and Rigid Rectangular Archwires.

A proper understanding of the force system created by various orthodontic appliances can make treatment of patients efficient and predictable. Reducing the complicated multi-bracket appliances to a simple two-bracket system for the purpose of force system evaluation will be the first step in this direction. However, much of the orthodontic biomechanics in this regard is confined to 2D experimental studies, computer modeling/analysis or theoretical extrapolation of existing models. The objective of this protocol is to design, construct and validate an in vitro 3D model capable of measuring the forces and moments generated by an archwire with a V-bend placed between two brackets. Additional objectives are to compare the force system generated by different types of archwires among themselves and to previous models. For this purpose, a 2 x 4 appliance representing a molar and an incisor has been simulated. An orthodontic wire tester (OWT) is constructed consisting of two multi-axis force transducers or load cells (nanosensors) to which the orthodontic brackets are attached. The load cells are capable of measuring the force system in all the three planes of space. Two types of archwires, stainless-steel and beta-titanium of three different sizes (0.016 x 0.022 inch, 0.017 x 0.025 inch and 0.019 x 0.025 inch), are tested. Each wire receives a single vertical V-bend systematically placed at a specific position with a predefined angle. Similar V-bends are replicated on different archwires at 11 different locations between the molar and incisor attachments. This is the first time an attempt has been made in vitro to simulate an orthodontic appliance utilizing V-bends on different archwires.

Autotransplantation: A biological treatment alternative for a patient after traumatic dental injury.

Traumatic dental injury is considered a public dental health problem because of a high childhood incidence, high treatment costs, and prolonged treatment time. Although management guidelines for traumatized teeth have been outlined, tooth loss following trauma is occasionally unavoidable. Here, we describe the successful interdisciplinary management of a traumatized central incisor in an 11-year old boy that was extracted because of a poor prognosis and restored by the autotransplantation of an immature donor tooth into the site. The patient underwent orthodontic treatment in order to close the donor site space and bring the autotransplanted tooth to an ideal position. Postorthodontic treatment radiographs and photographs revealed an esthetic and functional natural tooth replacing the lost tooth. The findings from this case suggest that autotransplantation offers unique advantages as a treatment modality for the restoration of missing teeth, particularly in growing children.

The effect of low-frequency mechanical vibration on retention in an orthodontic relapse model.

OBJECTIVE: To investigate the effect of low-frequency mechanical vibration (LFMV) on the prevention of relapse after active orthodontic tooth movement, bone volume fraction (BVF), tissue density, and the integrity of periodontal ligament. MATERIALS AND METHODS: Thirty male CD1, 12-week-old mice were used for the study. Mice were randomly divided into three groups: 1. control group, 2. relapse group, and 3. relapse + 30 Hz vibration group. In the control group, first molar was moved mesially for 7 days using nickel-titanium coil spring delivering 10g of force, whereas in relapse and relapse + 30 Hz groups, first molar was moved mesially for 7 days and then orthodontic force was removed and molar was allowed to relapse for 7 days. In relapse + 30 Hz group, LFMVs were applied at 30 Hz. Micro-focus computed tomography (micro-CT) was used for tooth movement measurements (relapse), BVF, and tissue density. Additionally, immunostaining for sclerostin, tartrate-resistant acid phosphatase staining, and picro-sirius red staining were performed on histological sections. RESULTS: LFMV at 30 Hz showed a tendency to decrease relapse but was not statistically significant. Micro-CT analysis showed a trend towards increase in BVF and tissue density with application of LFMV. Sclerostin expression was decreased with 30 Hz vibration. Additionally, the picro-sirius staining showed that LFMV at 30 Hz helped in maintaining the thickness and integrity of collagen fibres in periodontal ligament. LIMITATIONS: This is an animal study and extrapolation of the current findings to the clinical situation must be done with caution, as there is no osteonal remodelling (secondary remodelling) in mice when compared to humans. CONCLUSION: There was no statistically significant difference in the amount of relapse between the relapse-only and relapse + 30 Hz groups. However, there was a trend of decrease in relapse with 30 Hz mechanical vibration.

Integration of 3-dimensional surgical and orthodontic technologies with orthognathic "surgery-first" approach in the management of unilateral condylar hyperplasia.

Recent innovations in technology and techniques in both surgical and orthodontic fields can be integrated, especially when treating subjects with facial asymmetry. In this article, we present a treatment method consisting of 3-dimensional computer-aided surgical and orthodontic planning, which was implemented with the orthognathic surgery-first approach. Virtual surgical planning, fabrication of surgical splints using the computer-aided design/computer-aided manufacturing technique, and prediction of final orthodontic occlusion using virtual planning with robotically assisted customized archwires were integrated for this patient. Excellent esthetic and occlusal outcomes were obtained in a short period of 5.5 months.

Evaluation of alveolar bone dimensions in unilateral palatally impacted canine: a cone-beam computed tomographic analyses.

INTRODUCTION: The purpose of this study was to evaluate the alveolar bone dimensions and arch perimeter discrepancy in unilateral palatally impacted canines. METHODS: This retrospective split-mouth study reviewed 207 cone-beam computed tomography (CBCT) scans of patients with unilateral or bilateral impacted canines referred for orthodontic treatment. Out of 207 CBCT scans, only 39 scans in which canines were unilaterally palatally impacted were approved for the study based on our inclusion and exclusion criteria. Two fiducial lines were used to orient the examiners and standardize the measurements. Arch perimeter, buccopalatal (BP) width, and alveolar height were measured both on the impacted and non-impacted side. Two different examiners measured all the parameters. A one-sample Kolmogorov-Smirnov test was used to examine normality of distribution of outcomes. Wilcoxon Signed Rank tests were used for comparing arch width and alveolar bone height between the impacted and non-impacted sides. For arch perimeter, the paired-sample t-test was used. RESULTS: The arch perimeter, BP width, and alveolar bone height was significantly decreased on the impacted side (P < 0.05). The mean arch perimeter on the impacted side was 41.7 ± 2.5mm compared to 43.5 ± 2.37 on the non-impacted side. Similarly, BP width and alveolar bone height on the impacted side was 6.87 ± 1.08 mm and 18.12 ± 2.28 mm, respectively, whereas on the non-impacted side was 8.70 ± 1.13 mm and 19.49 ± 2.09 mm, respectively. CONCLUSION: There was a significant decrease in the arch perimeter and alveolar bone dimensions (BP width and alveolar bone height) on the impacted side.