International Orthodontics最新文献

Aim

Fluoride-Amorphous Calcium Phosphate and Biomimetic Nano-Hydroxyapatite for Enamel Remineralization; An In-Vitro Study of Surface Microhardness and Composition.

Material and methods

Ninety-six extracted human premolars with sound buccal surface were divided using a randomization computer-generating software into four groups; Group I (control) sound untreated enamel, Group II (demineralized) demineralized to create white spot lesions, Group III (biom-n-HA) demineralized and then treated with biomimetic nanohydroxyapatite cream, and Group IV (F-ACP) demineralized and then treated using Fluoride-Amorphous Calcium Phosphate varnish. Each group was divided into two subgroups; subgroup “A” evaluated for mineral content using energy dispersive x-ray spectroscopy (EDX) and for surface microhardness using the Vickers microhardness test and Subgroup “B” evaluated for white spot lesion depth using a polarized light microscope (PLM).

Results

The highest microhardness (VHN) was found in the (F-ACP) group (mean = 428.61 ± 54.43) and then in the (Biom-n-HA) group (mean = 408.11 ± 70.16) followed by the (Control) group (mean = 402.13 ± 53.40) with no significant difference between them and finally in the significantly different (Demineralized) group (mean = 256.99 ± 45.83). The weight percentage of Ca (30.29 ± 1.04 and 33.44 ± 1.07) and Ca/P ratio (1.87 ± 0.06 and 2.03 ± 0.05) were significantly different between Group III and Group IV respectively. PLM measurements in Group II (198.83 μm), Group III (60.17 μm), and Group IV (26.33 μm) were significantly different.

Conclusions

Both the (Biom-n-HA) cream and the (F-ACP) varnish showed promising results for enamel remineralization. The increased enamel surface microhardness was consistent with the mineral content and the changes in the birefringence.

Introduction

Mandibular canine impaction is infrequent in dental eruption anomalies and treatment is very challenging. The aim of this multicenter retrospective panoramic study in Latin America was to evaluate panoramic radiographic imaging characteristics of mandibular canine impaction (impaction area, mandibular base contact, transmigration, impaction height and sex) and their associations.

Material and methods

This cross-sectional study evaluated 212 digital panoramic radiographs from three radiological centres in Tingo Maria (Peru), Bogota and Tunja (Colombia). The study included children of both sexes with impacted mandibular canines. Mandibular alpha angle, contact with mandibular basal bone (MBB), impacted sector according to 10 sectors with an adaptation of the Ericson and Kurol method, presence of transmigration and the impacted height were measured and the relationship among these measures was analyzed. Fisher's exact test, Chi-square and binary logistic regression were used. (P < 0.05).

Results

The mandibular canine impaction showed contact with the MBB (32.08%), dental transmigration (36.79%), mainly located at an apical (40.09%) and sub-apical (36.79%) level. Transmigration mainly occurred in sectors 6 (33.30%) and 10 (25.60%) (P < 0.001). It was found that for each year of increase in age, the possibility of contact with the MBB decreased (β = 0.89, P = 0.010), and as the alpha angle increased by one degree the probability of contact with the MBB decreased (β = 0.97, P = 0.001) and the probability of transmigration increased (β = 1.05, P < 0.001).

Conclusions

One third of the impacted canines were in contact with the MBB, while another third presented dental transmigration and were mainly located apically and subapically of the incisor roots. These imaging features should be taken into account when planning orthodontic treatment.

Aim

Two-phase treatment for children with Class II malocclusion with several functional appliances is still performed by many orthodontists, while the Activator and the Bionator appliances are two of the most popular ones. Aim of this study was to compare the skeletal and dentoalveolar effects of treatment with these two appliances.

Methods

Class II children treated with Activator or Bionator in the first phase, followed by a phase of fixed appliances were included. Skeletal and dentoalveolar parameters were assessed from lateral cephalograms and analysed with linear regressions at 5%.

Results

A total of 89 patients (mean age 10.0 years; 47% female) were included. During the first phase, Bionator increased less the SNB (difference in mean treatment-induced changes [MD] –0.7°; 95% confidence interval [CI] –1.3 to –0.2°; P = 0.01) and decreased less the ANB angle (MD 0.6°; 95% CI 0 to 1.1°; P = 0.03) compared to Activator. Activator slightly increased the facial axis and Bionator reduced it (MD –1.6°; 95% CI –2.3 to –0.8°; P < 0.001). Compared to Activator, the Bionator retroclined more the upper incisors (MD –2.4°; 95% CI –4.6 to –0.2°; P = 0.03) and increased more the interincisal angle (MD 2.9°; 95% CI 0.5 to 5.4°; P = 0.02). After the second phase (6.2 years after baseline), the only differences were a reduced facial axis (MD –1.3°; 95% CI –2.2 to –0.3°; P = 0.008) and an increased maxillary rotation (MD 0.9°; 95% CI 0 to 1.8°; P = 0.04) with Bionator compared to Activator.

Conclusion

Similar dentoalveolar effects were seen overall with two-phase treatment with either appliance, with Bionator being associated with more vertical increase compared to Activator.

Introduction

We aimed to compare alveolar morphometry in young adults with agenesis of the upper lateral incisor versus the side without agenesis and versus matched controls.

Material and methods

In this observational retrospective study, cone beam computed tomography scans were obtained of 36 upper hemiarches from young adults aged 15 to 30 years. The hemiarches were distributed into three groups: group 1: 12 upper hemiarches presenting agenesis of the upper lateral incisor; group 2: 12 upper hemiarches from the opposite side without agenesis of the upper lateral incisor (control group 1); and group 3: 12 upper hemiarches without agenesis of the upper lateral incisor matched for age and sex with respect to the affected group (control group 2). A trained and calibrated investigator performed all the alveolar measurements at two different times, including sagittal, coronal and axial slices of each hemiarch. Paired Student's t-tests, Chi-square and repeated measures ANOVA with Bonferroni correction were used, (P < 0.05).

Results

Apical mesial evaluation of group 1 (4.22 ± 1.19 mm) was significantly lower (P < 0.001) than that of groups 2 (6.72 ± 1.17 mm) and 3 (7.58 ± 1.67 mm). Apical distal evaluation also showed differences (P < 0.001) among the three groups, with the dimension being smaller in group 1 with agenesis (4.53 ± 1.14 mm), followed by group 2 without agenesis (6.23 ± 1.55 mm) and the healthy control group 3 (7.73 ± 1.71 mm).

Conclusions

Lateral incisor agenesis significantly reduces the alveolar dimensions of the affected area. In cases of unilateral agenesis, the unaffected side also shows sequelae, with decreased dimensions compared to cases without agenesis. This condition should be taken into account when making therapeutic decisions regarding rehabilitation with implants or canine replacement.

This case report describes a complex full-step class II case in a young adult patient treated with lingual straight-wire appliance and upper first molar extraction. As the patient refused a surgical treatment, she was offered the best possible camouflage with the double aim of obtaining an ideal occlusal relationship and maintaining the profile; appropriate biomechanical strategies, including extraction choice and anchorage control during space closure, were needed to achieve the planned results. This case report demonstrates the possibility of successfully resolving severe sagittal discrepancies in an adult patient without surgical treatment by means of a completely invisible non-compliance technique, with the extraction of the most compromised teeth. This report also underlines the need for careful planning during both diagnostic and treatment phases, in order to obtain the best results.

Background

Facial soft tissue analysis is becoming increasingly emphasized in orthodontic diagnosis and treatment planning. While traditional cephalometry primarily focuses on hard tissues, recent non-invasive imaging techniques offer the potential to comprehensively evaluate three-dimensional (3D) facial soft tissues. The aim of the study was to establish the geometrical 3D and cephalometric divergence between Cone Beam Computed Tomography (CBCT) derived images and scanned soft tissues. Crucial for enhancing orthodontic diagnosis, minimizing patient exposure to ionizing radiation and providing facial cephalometric parameters.

Material and methods

A cross-sectional study was conducted from January 2020 to May 2023. CBCT and 3D facial scans were obtained simultaneously using a specialized imaging system. Reproducible landmark points were selected for both cephalometric and soft tissue analysis. Angular and linear measurements were recorded, and correlations between CT and facial scans were statistically assessed.

Results

Comparisons between 10 CBCT-derived and 10 facial scan-based soft tissue representations resulted into 1.8 mm mean root median square (RMS). Angular measurements, such as ANB, right gonial angle, and left gonial angle, exhibited a 0.9° of difference with their respective soft tissue variables. In contrast, linear measurements of total anterior facial height showed a lower correlation coefficient, equal to 0.51. The correlation between soft tissues and underlying hard tissues was more pronounced for gonial angles.

Conclusion

Facial soft tissue analysis using either 3D facial scans or CBCT-derived offers similar results for orthodontic diagnosis and treatment planning. These findings support the use of non-invasive diagnostic tools in orthodontics, although further investigations are needed to comprehensively understand the complexity of hard and soft tissue relationships.

Objective

This study aimed to evaluate how the addition of resveratrol nanoparticles (RNPs), which act as an antimicrobial agent, affects the strength of acrylic resin used in orthodontics.

Methods

According to ISO 20795-1-2013, 76 cold cure acrylic resin samples (65 × 10 × 3.3 mm) were prepared. The samples were divided into four groups (19 samples in each group) based on RN concentrations added to 1 mL acrylic monomer (0 for control, 256, 512, and 1024 μg/mL). Flexural strength was assessed in megapascal (MPa) using a universal testing machine. Data analysis involved nonparametric Kruskal-Wallis analysis of variance and pairwise post-hoc Dunn's test.

Results

The flexural strength decreased as the concentration of RNPs increased, with the lowest value observed at 1024 μg/mL (63.06 ± 5.33 MPa). The control group exhibited the highest mean of flexural strength (88.43 ± 4.41 MPa), followed by the groups with RNPs at the concentrations of 256 μg/mL (82.69 ± 4.41 MPa) and 512 μg/mL (76.02 ± 4.59 MPa).

Conclusion

In conclusion, the addition of RNs to orthodontic acrylic resin had a dose-dependent impact on its flexural strength. Based on the findings, we recommend incorporating RNs at a concentration of 256 μg/mL as an antimicrobial agent in orthodontic acrylic resin. However, further research is necessary to assess the long-term effects and clinical applications of this approach.

Non-surgical treatment of Class II subdivision may involve complex mechanics or asymmetric tooth extraction in its resolution. This report demonstrates the result and the short-term stability of Class II subdivision treated with asymmetrically installed Herbst appliance followed by conventional fixed orthodontic appliance. The approach allowed the correction of the unilateral Class II molar relationship and increased overjet, as well as the deviation of dental midlines, with improvement in lip posture and facial profile. The results remained stable two years after treatment, confirming the treatment success.