The mechanical testing and performance analysis of three-dimensionally produced lingual retainers.

BACKGROUND: Introducing three-dimensional (3D) printing has opened new visions in the orthodontic field. This research evaluates three-dimensionally produced orthodontic retainers and their future possible uses. For this purpose, in vitro tests were performed for these groups, including bond strength, failure analysis, discoloration, and biodegradation. METHODS: A total of 30 specimens (n = 30), lower incisor human teeth, were randomly divided into three groups for a bond strength failure analysis (for each group n = 10). In the experimental groups, lingual retainers were fabricated using 3D systems (group 1 with 3D dental pen and group 2 with 3D-printed). In the control group (group 3), the retainer system was a combination of a wire and composite, which is being used worldwide. A total of 30 specimens (n = 30) from the 3D dental pen and 3D-printed for discoloration and biodegradation tests were divided into three groups (water, tea, and coffee). Data were analyzed using the Mann-Whitney U test, ANOVA, and chi-square test. RESULTS: For all parameters tested, significant differences were determined among groups. The 3D pen group had the highest score for bond strength, whereas discoloration differed significantly. CONCLUSIONS: According to the limitations of this research, 3D-printed retainers have the potential for clinical use in the near future.

Three-dimensional zygomatic changes after rapid maxillary expansion in growing patients.

PURPOSE: To assess the effects of rapid maxillary expansion (RME) treatment on the zygomatic bone complex (ZBC). METHODS: In this single-center retrospective study, pre- and posttreatment cone-beam computed tomography (CBCT) images of 38 patients treated with RME were analyzed to investigate changes in the coordinates of the ZBC landmarks. At the start of treatment (T0), the patients' mean age was 11.1 ± 3.8 years (range 8.3-14.9 years). Cohen's d test was used to evaluate statistical differences. RESULTS: There were statistically significant differences between T0 and T1 (P < 0.01) in the measurement values for the maxillary transverse width (ΔT: 3.18 ± 2.58, d: 1.23), frontozygomatic sutures (ΔT: 1.09 ± 0.56, d: 0.43), lowest point of the zygomaticomaxillary sutures (ΔT: 3.16 ± 1.78, d: 0.78), frontomaxillary angular parameter (right side ΔT: 2.81 ± 1.63, d: 1.73; left side ΔT: 2.52 ± 1.20, d: 2.10), frontozygomatic angular parameter (right side ΔT: 2.81 ± 1.63 d: 1.07; left side ΔT: 2.21 ± 2.79, d: 0.61), anterior intermaxillary distance (ΔT: 2.11 ± 1.42, d: 0.99), interzygomaticotemporal distance (ΔT: 2.00 ± 2.42, d: 0.99), and zygomatic angular parameter (right side ΔT: 2.06 ± 1.29, d: 1.6; left side ΔT: 2.02 ± 1.86, d: 1.09). CONCLUSIONS: After RME in growing patients, the zygomatic bone showed pyramidal expansion in the coronal plane and parallel palatal expansion in the axial plane. In addition, significant lateral relocation of the zygomatic bone occurred. The zygomatic bone tended to rotate outward in conjunction with the maxilla, with a typical center of rotation close to the superior side of the frontozygomatic suture. These results shed light on the patterns of skeletal expansion in the zygomatic bone associated with RME in growing patients.

Fractal Perspective on the Rapid Maxillary Expansion Treatment; Evaluation of the Relationship Between Midpalatal Suture Opening and Dental Effects.

OBJECTIVE: This retrospective study investigates the relationship between the midpalatal suture opening and the dental effects of Rapid Maxillary Expansion (RME) treatment using fractal analysis. METHODS: The participants of this study were selected from the patients who underwent Cone Beam Computed Tomography(CBCT) scans in 2019 and were treated with banded type Maxillary Expander. This study included 20 participants (with a mean age of 10.64±10.64, ranging from 8 to 13 years): 12 males and 8 females. Patients went through CBCT scan and images taken were analyzed using the ImageJ program. The following parameters were measured and analyzed before and after RME treatment: fractal dimensional value of Midpalatal suture(MPS), Distobuccal(DB), Mesiobuccal(MB), Palatal(P), Total distance, Cortical bone and linear values of External maxilla, Internal maxilla, Palatal roots, distance of Central fosses and angular values of Tipping value of 16 and 26. We used Spearman's nonparametric test for non-normal variables to investigate the correlation between changes in MPS and other variables. RESULTS: The results showed a strong positive correlation between the MPS and Right MB (0.34, p<0.05) and Left MB (0.59, p<0.05) variables and a strong negative correlation between the MPS and the External maxillary variables (-0.53, p<0.05). CONCLUSION: The results of the study have shown a strong correlation between right and left MB and External Maxilla. RME caused a reduction in buccal alveolar bone thickness and a slight reduction in MPS thickness in growing patients. Therefore, we suggest that fractal analysis can be used to evaluate the skeletal and dental effects of RME in patients.

Is there a relationship of nasal septum deviation with pharyngeal airway dimension and craniocervical posture?

OBJECTIVE: This study aimed to evaluate the effects of nasal septum deviation on the pharyngeal airway and craniocervical posture measurements using cone beam computed tomography (CBCT). METHODS: This retrospective study analyzed the CBCTs of 25 patients with and without nasal septum deviation. Various parameters defining the pharyngeal airway and craniocervical and facial skeletal morphology were measured and compared between the groups after confirming intra-examiner reliability. RESULTS: Compared to the control group, the group with nasal septum deviation had a statistically significantly shorter nasopharyngeal length (p < 0.001), longer vertical airway length (p < 0.002), and larger cervical column curvature angle (p < 0.006). CONCLUSION: Children with a nasal septum deviation of 4 mm or more on their CBCT scan are susceptible to unfavorable pharyngeal airway and craniocervical postural changes.

Single-component orthodontic adhesives: comparison of the clinical and in vitro performance.

OBJECTIVES: To investigate the clinical and in vitro performance of single-component orthodontic adhesives under metal brackets. MATERIALS AND METHODS: Bimaxillary orthodontic treatment was required for sixty patients and 60 premolar teeth were divided into three groups (n: 20). The single-component orthodontic adhesives Biofix and GC Ortho Connect (GC) that did not require primers were compared to the control group using Transbond XT, which was applied with a primer. For each patient, total bonding time was measured. The Adhesive Remnant Index (ARI(Bracket)) score was noted over 12 months. In vitro tests were used to evaluate specimens, shear bond strength (SBS), ARI(Bracket), and Enamel Surface Index (ESI). After in vitro debonding, the enamel surface and bracket base were analyzed using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). RESULTS: Clinical failure rate with primer was 9.0%, while it was 8.0 and 10.0 for GC and Biofix, respectively. The mean in vitro SBS values of the Biofix, GC, and Transbond XT groups were 8.21, 8.07, and 7.37 MPa, respectively. There were no statistically differences in clinical failure (p = 0.160) and SBS values (p = 0.158). Mean differences in bond-up time per jaw were 9.65, 10.51, and 11.97 min, which were statistically significant (p = 0.0001). CONCLUSION: Single-component adhesives had acceptable SBS values and enamel effects according to SEM-EDX analysis. Clinically, bonding failure was not shown statistically inferior to bonding with primer. There was also a significant difference in bond-up times. CLINICAL RELEVANCE: Considering an intensely working clinic with bonding processes for at least two jaws per day, this means a saving of the chair time of 1 patient per week. However, better saliva contamination and moisture control with lack of the primer stage and, thereby, an acceptable bracket failure rate will bring clinically significant results with less chair time for clinicians.

Alternative treatment plan for congenitally missing teeth in an adolescent patient: A case report.

BACKGROUND AND OVERVIEW: Mandibular second premolars are the second most commonly missing teeth, and there are various treatment alternatives to restore the space of the missing teeth. However, in growing patients, implants are contraindicated because they prevent growth of bone. CASE DESCRIPTION: In this case report, the authors describe a 13-year-old girl with Class II malocclusion with congenitally missing mandibular second premolars. Autotransplantation of 2 maxillary premolars to the missing teeth site was performed considering the presence of crowding in the maxillary anterior segment. The teeth were fixed with a semirigid splint for 3 months. The patient had an acceptable occlusion at the end of the orthodontic treatment, which lasted 20 months. CONCLUSIONS AND PRACTICAL IMPLICATIONS: The autotransplanted right premolar showed normal physiological adaptation, whereas the tooth on the left side was ankylosed. The short-term results show that autotransplantation, which requires high technical sensitivity, may provide a biological and economical alternative to tooth replacement.