Bracket Failure in Orthodontic Patients: The Incidence and the Influence of Different Factors

Failure of brackets is a common problem in orthodontics. This affects the treatment time, cost, and compliance of the patient. This study was conducted to estimate the bracket failure rate and the related factors for the long term. Methodology. This ambidirectional cohort study included 150 nonsyndromic orthodontic patients undergoing fixed appliance therapy for the last two years. The same patients were followed for 7 months. Different variables related to bracket failure were evaluated. The available data were analyzed descriptively, and the Kaplan-Meier estimate was used to measure the bracket survival rate from the date of bonding to failure. Results. A total of 180 bracket bond failures in the 150 included patients (52.2% males and 47.8% females) with a median age of 17 years (range 10-25 years). 69% of brackets failures were reported within the first 6 months after bonding. About 58.3% of bracket failure was noticed in adolescent patients before the age of 18 years. The majority of the cohort (81.1%) has good oral hygiene. The failure rate in patients with normal overbite was 41.1%, in decreased overbite cases was 15%, while in deep bite cases the failure rate was 43.9% with a statistically significant difference. Adults show less bracket failure (41.7%) than adolescent patients (58.3%). More bracket failure was noted in the lower arch (55%) than the upper arch (45%), and there were more bond failures posteriorly (61%) than on the anterior teeth (39%). Majority (41.1%) of the bracket failed on round NiTi wires. Conclusion. The bracket failure rate was 6.4%, with most bracket failure occurring in the first 6 months after bonding with individual difference. There was more incidence of bond failure in an increased overbite, adolescents, lower arch, posterior teeth, and lighter alignment wires.

Structural Performance of Thin-Walled Twisted Box-Section Structure

The light weight and high strength-to-mass ratio of thin-walled boxed sections have incited interest in their widespread use in the construction of domes. However, the installation of these sections in forming the dome geometry has induced initial twists and curving features, to which their mechanical response has rarely been explored. Therefore, the structural performance of a structure with thin-walled twisted box sections is numerically studied in this paper, employing ANSYS, the verification of which is carried out through a comparison with experimental results. Additional components examined include the longitudinal stiffening rib, diaphragm, and web. The effects of variations in the thicknesses of these member plates on the mechanical behaviors are investigated. In general, the ultimate capacity of the structure is improved by increasing the thickness of the longitudinal stiffening rib, diaphragm, and web, but the strengthening effect of the stiffener is limited by a certain thickness enhancement. The common failure mode of the initial model is found to be an overall elastic-plastic buckling. A reduction in the thickness of the stiffener or web creates a curving deformation zone in the lower arch at the ultimate capacity, whereas the diaphragm thickness has little effect on the failure mode of the model.

Effects of obesity and foot arch height on gait mechanics: A cross-sectional study

Foot arch structure contributes to lower-limb joint mechanics and gait in adults with obesity. However, it is not well-known if excessive weight and arch height together affect gait mechanics compared to the effects of excessive weight and arch height alone. The purpose of this study was to determine the influences of arch height and obesity on gait mechanics in adults. In this study, 1) dynamic plantar pressure, 2) spatiotemporal gait parameters, 3) foot progression angle, and 4) ankle and knee joint angles and moments were collected in adults with normal weight with normal arch heights (n = 11), normal weight with lower arch heights (n = 10), obesity with normal arch heights (n = 8), and obesity with lower arch heights (n = 18) as they walked at their preferred speed and at a pedestrian standard walking speed, 1.25 m/s. Digital foot pressure data were used to compute a measure of arch height, the Chippaux-Smirak Index (CSI). Our results revealed that BMI and arch height were each associated with particular measures of ankle and knee joint mechanics during walking in healthy young adults: (i) a higher BMI with greater peak internal ankle plantar-flexion moment and (ii) a lower arch height with greater peak internal ankle eversion and abduction moments and peak internal knee abduction moment (i.e., external knee adduction moment). Our results have implications for understanding the role of arch height in reducing musculoskeletal injury risks, improving gait, and increasing physical activity for people living with obesity.

Effects of Gender and Age in Mandibular Leeway Space for Taiwanese Children

Purpose: Leeway space is clinically crucial in pediatric dentistry because it is utilized to resolve tooth crowding and allow the first molars to drift mesially to establish a Class I molar relationship in the later stages of mixed dentition. This study investigated leeway space in the mixed dentition of Taiwanese children of different sexes and ages. Materials and Methods: The digital panoramic dental films of 182 lower arches of 119 boys and 63 girls aged 5–10 years were analyzed in this retrospective study. The mesiodistal crown widths of the primary canines and first and second molars and the permanent canines and first and second premolars were measured using medical imaging software. Differences in leeway space were statistically analyzed. Results: The average leeway space was 1.29 ± 1.48 mm on each side of the lower arch. The leeway space of children aged 5–6 years was significantly greater than that of children aged 7–8 years. No gender difference in crown width was discovered, except with regard to the primary first molar. Although no gender difference in leeway space was observed, permanent teeth affected leeway space more for girls than for boys. Conclusion: In Taiwanese children, although leeway space does not differ by sex, age affects leeway space. However, permanent tooth size has an influence on the leeway space of girls.

Fabrication of Hollow Maxillary Complete Denture Using Silicon Putty and Double Flask Technique

This article describes the fabrication of a hollow maxillary complete denture using silicone putty and a double flask technique. A successful complete denture directly depends on retention, stability and support accompanied by good aesthetics. However, in case of atrophic edentulous ridges the challenge lies in the fact that there is a significantly lesser denture bearing area that can lead to a number of problems. The most important of these is an increased interarch space resulting from excessive resorption of upper or lower arch. This can lead to a resulting heavy complete denture that further deteriorates the bone condition due to excessive and continuous load, accelerating bone resorption. Moreover, there is no effective support to deal with any kind of harmful lateral forces and this can lead to dislodgment of the denture. The operator’s efficiency lies in applying the basic principles of fabricating a denture and innovating various steps to counter critical situations. Various methods such as asbestos, silicone putty, modelling clay, thermocol, salt, wax have been used for creating a hollow space inside the denture. Out of the various methods that have been used for fabrication of a hollow space inside a complete denture, silicone putty method is one of the more convenient and accurate method for achieving the objective, thereby rendering a lighter prosthesis. A hollow maxillary denture is highly advantageous as it reduces the weight of acrylic resin, thereby preserving the residual alveolar ridge. It also helps in stability of the denture by indirectly reducing the lateral forces.

Prediction of arch perimeter based on arch width as a guide for diagnosis and treatment planning

Background The choice between extraction and expansion treatment is an endless debate in orthodontics. Ethnic and secular variations showed that there was a change in arch perimeter over the last 50 years. Accordingly, the purpose of this study was to investigate the relation between the arch perimeter and the intercanine and intermolar widths in normal occlusion. Also, to design regression equations for the prediction of the arch perimeter based on arch width, in a sample of the Egyptian population. The images of 340 cast pairs for 11 to 13-year-old patients were traced using TracerNet. Intercanine width, intermolar width and arch perimeter were measured, statistical analysis was performed and regression equations for both arches were formulated. Results There was a positive correlation between the lower arch AP, ICW and IMW and between the upper arch AP and ICW. Lower arch perimeter = 0.536 I33 + 71.642, lower arch perimeter = 0.828 l66 + 58.604 and upper arch perimeter = 1.988 U33 + 30.492 were the significant derived equations. Conclusions The formulation of regression equations offers a tool for the prediction of arch perimeter or arch width that can act as a guide in diagnosis and treatment planning.

Occlusion and occlusal characteristics of the primary dentition in Emirati schoolchildren

Background: The prevalence of occlusion and various occlusal characteristics differ between populations. Major contributions to these different types of occlusion and occlusal features include ethnic, genetic and environmental factors. Purpose: The objective of the study was to understand the type and prevalence of terminal plane relationships and other occlusal traits, including physiological spacing and primate spacing, in Emirati schoolchildren. Methods: A cross-sectional study was conducted involving 458 participants in the age range of 3–6 years. A clinical evaluation was performed to record other occlusal characteristics. The data was then subjected to statistical analysis. Results: The present study revealed that the bilateral flush terminal plane was seen in 40.8% of the examined children, the bilateral mesial step in 37.3% and the bilateral distal step in 1.7%. It was found that 44.5% of the examined children had physiologic space in both the upper and lower arches, while 14.19% of them had physiologic space only in the upper arch, 2.18% had it only in the lower arch, and 39% of them had no physiologic space. Primate space was found to be present in both the upper and lower arches in 46% of the examined children. Conclusions: The bilateral flush terminal plane relationship was the most common, and the bilateral distal step was the least common of the terminal plane relationships. In addition, primate spacing had a lower prevalence when compared to other studies.

UNILATERAL BIJAW PREMOLAR EXTRACTIONS FOR CORRECTION OF CROWDING, BUCCALLY PLACED CANINES AND ASYMMETRIC DENTAL MIDLINE - A CASE REPORT

This case report is of a 22 year old male patient who presented with irregularly placed and crowded teeth in bothmaxillary and mandibular arch on the right side with both upper and lower dental midlines shifted to the patients right. This case was corrected non surgically merely by employing simple mechanics with the help of Fixed Orthodontic Mechanotherapy by extracting a single maxillary and mandibular 1st premolar of right side followed by retraction and closure of spaces with the help of Elastomeric chains. The case ended in a Class I Molar and canine relationship bilaterally. The case report emphasizes on the need for extracting 1st premolars only on 1 side in the upper and lower arch for the purpose of correcting the shifted dental midlines. The extractions also favour correction of crowding and buccally placed upper and lower canines on the right side. Following fixed orthodontic treatment, marked improvement in patients smile was achieved and there was a remarkable increase in the patients confidence and quality of lifeThe profile changes and treatment results were demonstrated with proper case selection and good patient cooperation with Fixed appliance therapy. The patient was extremely satisfied with the results at the end of treatment.

Comparative Analysis of Periodontal Pain According to the Type of Precision Orthodontic Appliances: Vestibular, Lingual and Aligners. A Prospective Clinical Study

The objective of this prospective clinical study was to analyze the pain (intensity, location and type) that patients presented after the placement of different types of orthodontic appliances: conventional, low friction, lingual and aligners. The sample consisted of 120 patients divided into four groups: conventional (CON), low friction (LF), lingual (LO) and aligners (INV). The participants were given the Short-Form McGill Pain Questionnaire (Ortho-SF-MPQ), where they had to record the pain intensity (no pain, mild, moderate or intense) and the periodontal location at different time points, from the first 4 h to 7 days after the start of treatment. In all the study groups, the most frequent location was both anterior arches, with maximum values between 56.7% (CON group at 24 h) and 30% (LO group at 4 h). The “whole mouth” and “complete lower arch” locations were indicated only by the patients in the lingual group. Regarding pain intensity, the patients reported a higher percentage of mild–moderate pain during the first 3 days of treatment (96.7% in LO at 4 h, 86.7% in CON, 83.3% in LF and 90% in INV at 24 h); later, the reported pain decreased to no pain/mild pain, especially in the lingual group, until reaching values close to zero at 7 days post-treatment. The most frequent type of pain was acute in the low friction and lingual groups (with maxima of 60% and 46.7% at 24 h, respectively). On the contrary, in the conventional (36.7% at 4 h) and Invisalign (40% at 24 h) groups, the sensitive type was the most frequent. There are differences regarding periodontal pain in its intensity, location and type according to the use of different orthodontic techniques.

Enamel interproximal reduction during treatment with clear aligners: digital planning versus OrthoCAD analysis

Background The aim of the study was to compare the amount of interproximal enamel reduction (IPR) provided on ClinCheck software with the amount of IPR carried out by the orthodontist during treatment with clear aligners. Methods 30 subjects (14 males, 16 females; mean age of 24.53 ± 13.41 years) randomly recruited from the Invisalign account of the Department of Orthodontics at the University of Rome “Tor Vergata” from November 2018 to October 2019, were collected according to the following inclusion criteria: mild to moderate dento-alveolar discrepancy (1.5–6.5 mm); Class I canine and molar relationship; full permanent dentition (excluding third molars); both arches treated only using Comprehensive Package by Invisalign system; treatment plan including IPR. Pre- (T0) and post-treatment (T1) digital models (.stl files), created from an iTero scan, were collected from all selected patients. The OrthoCAD digital software was used to measure tooth mesiodistal width in upper and lower arches before (T0) and at the end of treatment (T1) before any refinement. The widest mesio-distal diameter was measured for each tooth excluding molars by “Diagnostic” OrthoCAD tool. The total amount of IPR performed during treatment was obtained comparing the sum of mesio-distal widths of all measured teeth at T0 and T1. Significant T1–T0 differences were tested with dependent sample t-test (P < 0.05). Results In the upper arch, IPR was digitally planned on average for 0.62 mm while in the lower arch was on average for 1.92 mm. As for the amount of enamel actually removed after IPR performing, it was on average 0.62 mm in the maxillary arch. In the mandibular arch, the mean of IPR carried out was 1.93 mm. The difference between planned IPR and performed IPR is described: this difference was on average 0.00 mm in the upper arch and 0.01 in the lower arch. Conclusions The amount of enamel removed in vivo corresponded with the amount of IPR planned by the Orthodontist using ClinCheck software.