Evaluation of maxillary arch dimensional and inclination changes with self-ligating and conventional brackets using broad archwires

Effect of time between archwire changes on intended dentoalveolar expansion in orthodontic patients treated with fixed appliances : A prospective controlled clinical trial

OBJECTIVE

To analyze the effects of the time span between archwire changes on the amount of transverse dental arch expansion. The design was a prospective, controlled clinical trial. Randomization was performed by computer-generated allocation tables.

METHODS

In all, 35 patients were evaluated in three groups treated with fixed appliances and the same four sequential leveling archwires, however, with different replacement periods: 28 days (4-week [4W] group), 56 days (8-week [8W] group), and 84 days (12-week [12W] group). Digital models were measured before the treatment (T0) and at the end of the evaluation period (T1) by a blinded operator with OrthoAnalyzer® software (3-Shape, Copenhagen, Denmark) and compared using MANOVA. A multiple linear regression was also used to evaluate the influences of age, initial dental crowding, incisor inclination, and facial pattern on the amount of expansion.

RESULTS

Mean expansion was 2.77 ± 0.84 mm (upper arch) and 3.12 ± 0.88 mm (lower arch) in the 12W group; 1.96 ± 0.82 mm and 2.27 ± 0.96 mm in the 8W group, and 1.11 ± 0.93 mm and 1.32 ± 0.91 mm in the 4W group, respectively for the upper and lower arches. The amount of expansion varied significantly between the groups in the area of the canines, first premolars, and second premolars for both arches. Expansion was less in older patients. Initial dental crowding, incisor inclination and facial pattern had no influence on dental expansion.

CONCLUSION

Longer time spans between archwire changes provided greater amounts of expansion, while age is inversely related, with younger patients expressing greater amounts of expansion. The results also suggest that the expansion provided by the fixed appliances is expressed mainly in the canine and premolar areas.

Comparison of transverse dimensional and incisor changes between wide and narrow orthodontic archwires: a randomized controlled trial

OBJECTIVES

To clinically compare the effects of broader archwires to standard archwires, using conventional brackets in both cases, on the transverse and incisor changes in maxillary and mandibular arches during leveling and alignment.

MATERIALS AND METHODS

Fifty-two patients presenting with crowding were allocated into two groups; one group received the broad Damon archwires while the other received standard 3M OrthoForm III Ovoid archwires. All participants were treated with conventional brackets using similar archwire sequences (0.014, 0.018, 0.016 × 0.022/0.016 × 0.025, 0.019 × 0.025 NiTi/CuNiTi archwires). Digital casts were obtained from alginate impressions before treatment (T0) and six weeks after inserting 0.019 × 0.025 NiTi archwires (T1). Pretreatment (T0) and post-alignment (T1) lateral cephalograms were obtained for each patient. The primary outcomes were the changes in the transverse arch dimensions and incisor inclination. The secondary outcomes were the horizontal and vertical linear changes in incisor position.

RESULTS

Complete data were collected for 47 patients. There was a significant increase in arch width during treatment within each group, except for upper inter-molar width in 3M group (P = 0.071). Damon wire induced a statistically significant increase in maxillary inter-second premolar width (P = 0.042), and mandibular inter-first premolar (P = 0.043), inter-second premolar (P = 0.008) and inter-molar widths (P = 0.033) compared to 3M group. The increase in incisor proclination and the linear change in incisor position were significant within each group, with less mandibular incisor proclination (P = 0.004) and horizontal advancement (P = 0.038) in the Damon group.

CONCLUSIONS

Damon archwires created a comparatively greater increase in the maxillary inter-second premolar width and the mandibular inter-first premolar, inter-second premolar, and inter-molar widths, and less proclination and horizontal advancement in mandibular incisors. The study provides invaluable evidence that using broad archwires with self-ligating brackets is the reason behind any greater expansion observed in this system rather than the unique mechanical and biological features exerted by the self-ligating system.

CLINICAL RELEVANCE

Our results suggest that Damon archwire might be a better alternative compared to the narrower standard archwires that are usually used with conventional brackets, especially in the mandibular arch, in cases where mild to moderate crowding is planned to be resolved with a non-extraction approach. However, as arch expansion in the absence of posterior crossbites raises the question of long-term stability, the reported advantage of the use of wide wires should be interpreted with caution and should be considered in the retention phase, bearing in mind that achieving a good post-treatment occlusion is important for enhancing post-treatment stability.

Deflection of tandem archwire in a specific self-ligating metal bracket system: an in vitro study

The aim of this study was to quantify the force exerted by tandem archwires in a specific system of passive self-ligating bracket. Forty-eight thermo-activated nickel-titanium orthodontic archwires were separated into four groups (n = 12): G1 - two .014" + .014" round archwires; G2 - two .014" + .016" round archwires; G3 - .014" x .025" rectangular archwire; and. G4 - .016" x .022" rectangular archwire. Brackets were fixed onto teeth 1.5 to 2.5 using a device that represented the upper teeth, maintaining an interbracket distance of 6.0 mm. The deflection tests were performed using the structure representative of tooth 1.1 as support on the Instron testing machine at a speed of 2.0 mm/min. The archwires were evaluated at deflections of 0.5 mm, 1.0 mm, and 1.5 mm. The data were analyzed by a generalized linear model, considering values at different deflections as repeated measurements in the same experimental unit (α = 0.5%). At 0.5 mm, higher forces were observed in G2 and G3, which did not differ significantly (p > 0.05). The lowest force was observed in G4 (p < 0.05). At 1.0 mm and 1.5 mm, the highest force was observed in G3, followed by G4 and G2 (p < 0.05). The lowest force was observed in G1 (p < 0.05). In general, tandem archwires (same or different calibers) in a specific passive self-ligating bracket exerted lower force when compared with rectangular archwires.

Assessment of Dentoalveolar Changes Following Leveling and Alignment of Severely Crowded Upper Anterior Teeth Using Self-Ligating Brackets Alone or With Flapless Piezocision Compared to Traditional Brackets: A Randomized Controlled Clinical Trial

Introduction Dental crowding is one of the most common types of malocclusions. It can be treated with or without extraction, depending on the severity of the crowding. Extraction-based orthodontic treatments are the preferred treatment option in cases of severe crowding, but they take longer than non-extraction cases. Objective This study aimed to evaluate the dentoalveolar changes following the orthodontic treatment of severely crowded maxillary anterior teeth in adults using self-ligating brackets alone or combined with flapless piezocision. Materials and methods The participants in this study were 63 patients (46 females and 17 males; mean age SD: 19.71 ± 2.74 years) who attended the Department of Orthodontics at the University of Damascus from January 2020 to December 2021. The participants were divided into three groups at random: Group (1): traditional brackets group, Group (2): self-ligating brackets group; and Group (3): self-ligating brackets with flapless piezocision group. Little's Irregularity Index (LII) was measured at five assessment times: before the onset of orthodontic treatment (T0), after one month (T1), after two months (T2), after three months (T3), and at the end of the leveling and alignment phase (T4). The intercanine width (lingual), the intercanine width (cusp), and the canine rotation angle were measured at two assessment times: before the onset of orthodontic treatment (T0) and at the end of the leveling and alignment phase (T4). Results The three studied groups had statistically significant differences in terms of LII during the first three months, and the most significant improvement of LII was in the self-ligating brackets with the piezocision group (P < 0.001). In addition, the intercanine width (cusp) at the end of the leveling and aligning phase revealed greater mean values in both self-ligating brackets groups compared to the traditional brackets group, and the differences were statistically significant (P < 0.001). Otherwise, no statistically significant differences were found at the end of the leveling and aligning phase in the intercanine width (lingual) or the canine rotation angle between the three studied groups (P > 0.05). Conclusion Using self-ligating brackets with flapless piezocision revealed more significant results concerning LII as compared to other groups. Thus, combining these two acceleration methods could get more effective results in aligning severely crowded teeth. Self-ligating brackets, whether used alone or with flapless piezocision, resulted in greater intercanine width at the cusp level. The type of brackets (traditional or self-ligating) did not affect the canine rotation angle.

Comparative assessment of dental and basal arch dimensions of passive and active self-ligating versus conventional appliances : A randomized clinical trial

PURPOSE

In this parallel, three-arm, single-center randomized trial, the dental and basal arch dimensions after orthodontic treatment using conventional brackets and passive and active self-ligating (SL) brackets were compared.

METHODS

Patients needing comprehensive orthodontic treatment were randomly allocated to the active SL, passive SL, or conventional brackets (control) group. All patients were treated with a standardized arch wires sequence. Eligibility criteria included class I malocclusion in the permanent dentition, crowding (4-6 mm), and adequate oral hygiene. The primary outcome was intermolar width, based on cone beam computed tomography (CBCT) scans. Secondary outcomes were maxillary and mandibular widths in the canines and premolars regions, dental arch depth, buccolingual inclination, and alignment duration. Blinding of outcome assessment was implemented. Patients were followed every 4 weeks until insertion of the stainless steel 0.019 × 0.025 wire. Mean values were computed from CBCT sections, and data were analyzed using a one-way analysis of variance.

RESULTS

In all, 66 patients (ages 18-25 years) were randomized into a 1:1:1 ratio; 7 patients dropped out before treatment initiation. Examining dental arch dimensions in the canine and premolar regions showed that expansion of the maxillary dental arch was greatest in the passive SL brackets group, less in the active SL brackets group, and lowest in the control group (P < 0.01). Changes in maxillary intermolar width between the three groups were not significant, and changes in basal arch dimensions, depth of dental and basal arches, buccolingual inclination, and alignment duration were similar in the three groups.

CONCLUSIONS

Self-ligating brackets were not more effective than conventional brackets when examining intermolar width, basal transverse dimensions, depth of the arch, and alignment duration.

Effect of Low-Intensity Pulsed Ultrasound (LIPUS) on Alveolar Bone during Maxillary Expansion Using Clear Aligners

The present study evaluated the possible effect of low-intensity pulsed ultrasound (LIPUS) on buccal bone plate thickness and height after maxillary arch expansion using clear aligners. The cone beam computed tomography (CBCT) of before and immediately after maxillary arch expansion (3 mm per side) of 28 adult patients (18 in LIPUS group and 10 in control) (average age $36.2\pm 13.2$ years old) was analyzed. The wearing protocol of clear aligners in the LIPUS group was to change the aligners every 4 to 5 days, while the wearing protocol in the control group (without LIPUS) was to change the aligners every 7 to 10 days. Bone thickness at 3 mm and 6 mm from the buccal alveolar bone crests, along with the measurements of buccal alveolar bone heights, was measured in standardized sagittal sections. Data were analyzed through paired sample $t$ -test and the Wilcoxon test. The results were given as $\text{mean}\pm \text{standard}\text{deviation}$ and 95% confidence intervals. $p$ value < 0.05 was considered statistically significant. The results showed significant increase in bone height in both groups. However, comparison of both LIPUS and control groups showed no statistically significant difference in bone thickness or bone height. The results of this study showed that the use of LIPUS together with accelerated aligner tray change protocol did not affect alveolar bone integrity when compared to the control group.

Is there any difference between conventional, passive and active self-ligating brackets? A systematic review and network meta-analysis

AIM

To test the null hypothesis that there was no difference in treatment efficiency between therapies undertaken with conventional (CBs), passive self-ligating (PSLBs) or active self-ligating (ASLBs) brackets.

MATERIALS AND METHODS

An electronic search was performed in 3 data bases (Pubmed, Web of Science, Cochrane Library) from their origin up to January 2019. Additional references were hand searched. Search was strictly restricted to randomized controlled trials (RCTs) and split-mouth design studies (SMDs). RCTs and SMDs were initially processed separately and subsequently combined in a network meta-analysis. The following variables were evaluated: treatment duration, number of visits, occlusal outcomes, alignment rate, transverse arch dimensional changes, incisor position modification, rate of space closure, anchorage loss, bond failure, root resorption, perception of discomfort during the initial phase of alignment, time to ligate in or to untie an archwire, periodontal variables, quality of life.

RESULTS

On 229 papers, 30 RCTs and 9 SMDs were finally included in this study. Out of 85 comparisons, 16 only revealed statistically significant differences. It was quicker to untie and ligate an 0.014 NiTi arch from/in 6 ASLBs anterior ceramic brackets compared to 6 ceramic CBs. It was also more painful to insert and remove an 0.019×0.025 SS wire in/from PSLB's brackets compared to CB's attachments. Compared to conventional brackets, there was less maxillary incisor proclination with PSLBs in non-extraction cases. Moreover, there was less bleeding on probing 4-5 weeks after bonding with PSLBs compared to CBs brackets. The only significant difference between ASLBs and PSLBs was that alignment was 10 days faster with active self-ligating braces compared with passive self-ligating braces even if treatment duration between ASLBs and PSLBs was not significantly different. The network meta-analysis revealed that IMPA was greater in extractions cases with CBs compared with both ASLBs (+2,5°) and PSLBs (+1,6°).

CONCLUSIONS

The vast majority of the studied variables did not show any significant differences between the three types of brackets. The most significant findings were that it was quicker to insert and remove archwires from ASLBs compared to CBs, and it was more painful to insert and remove an 0.019×0.025" stainless steel wire in/from PSLBs compared to CBs. The major difference between ASLBs and PSLBs was that alignment was 10 days faster with active self-ligating braces compared with passive self-ligating braces even if treatment duration between ASLBs and PSLBs was not significantly different. Most of the claims put forward by the suppliers were not substantiated by our network meta-analysis.

Implications of pretreatment incisor inclinations for the achievement of cephalometric normal values-a study on two patient collectives

PURPOSE

The objective was to clarify whether standardized multibracket therapies-differing only in finishing-wire dimensions (0.016 × 0.022 inch vs. 0.017 × 0.025 inch CNA [Connecticut New Archwire]) and excluding any extraction treatment or additional appliances other than intermaxillary elastics-can produce normal incisor inclinations starting from different baseline inclinations.

METHODS

We analyzed pre- and posttreatment cephalograms of 156 patients (age: 15.6 ± 1.3 years) treated with Roth system (0.018 inch slot). Each archwire group (n = 89 or 67) was divided into subjects with initially retroclined, orthograde, or proclined upper and/or lower incisors (U1, L1). For the resultant 12 subgroups, descriptive statistics were compiled relative to five reference planes (NL, ML, NA, NB, BOP), followed by multiple intragroup (Kolmogoroff-Smirnoff and Wilcoxon signed-rank test) and intergroup (Kruskal-Wallis and Mann-Whitney U test) comparisons relative to NL or ML.

RESULTS

The following intra- (1, 2) and intergroup (3, 4) differences were statistically significant (p ≤ 0.05) in both archwire groups: (1) post- vs. pretreatment inclinations in the subgroups initially retroclined U1, retroclined L1 and orthograde U1, but without normal values being achieved (subgroups retroclined U1, L1) or preserved (subgroup orthograde U1); (2) observed vs. expected alterations for the subgroups initially orthograde and proclined U1 and L1; (3) posttreatment inclinations for the subgroups initially retroclined vs. orthograde L1 and proclined L1; (4) observed alterations for the subgroups initially retroclined vs. proclined U1 and L1, but neither retroclined nor proclined vs. orthograde. Archwire thickness influenced the outcome to only a limited extent under the special circumstances of this study.

CONCLUSION

The bracket/archwire combinations evaluated did not lead to normal incisor inclinations in most cases. Posttreatment values did significantly depend on the pretreatment situation. Most frequently, alterations were protrusive in direction, which notably even included incisors that showed norm values at the outset of treatment. It can be concluded that bracket torque will influence but not dominate incisor inclinations.

Maxillary arch development with Invisalign system

OBJECTIVES

To evaluate tooth movements during maxillary arch expansion with clear aligner treatment.

MATERIALS AND METHODS

The study group included 28 subjects (16 females, 12 males, mean age 31.9 ± 5.4 years) collected prospectively from January 2018 to May 2019. Inclusion criteria were European ancestry, posterior transverse discrepancy of 3-6 mm, permanent dentition stage, presence of second permanent molars, mild or moderate crowding, and good compliance with aligners. Treatment protocol included nonextraction strategies, application of Invisalign clear aligner system, and no auxiliaries other than Invisalign attachments. Linear and angular measurements were performed before treatment (T1), at the end of treatment (T2), and on final virtual models (T2 ClinCheck). A paired t-test was used to compare T2-T1 and T2-T2 ClinCheck changes. The level of significance was set at 5%.

RESULTS

Statistically significant differences were found for all measurements, except for ones at the upper second molars. The greatest increase in maxillary width was detected at the upper first and second premolars: +3.5 mm for the first premolar and +3.8 mm for the second premolar at T2. Comparison of T2-T1 angular outcomes showed statistically significant changes in the inclinations of all teeth except for the second permanent molars. T2-T2 ClinCheck showed significant differences for both linear and angular measurements for maxillary canines, resulting in poor predictability.

CONCLUSIONS

Maxillary arch development revealed a progressive reduction of the expansion rate and buccal tipping in the anterior, lateral, and posterior regions, with the greatest net increase at the first and second premolars. Clinical attention should be paid to maxillary canine movements, and overcorrection should be planned for them during dentoalveolar expansion.

Transverse stability of Class II malocclusion correction with the pendulum appliance

INTRODUCTION

This study aimed to evaluate the stability of transverse changes after Class II malocclusion correction with the pendulum fixed distalizer, followed by preadjusted edgewise fixed orthodontic appliances.

METHODS

This longitudinal study was conducted in the maxillary dental casts of 20 Class II malocclusion subjects (mean age, 12.5 years; 14 females and 6 males). Eighty 3-dimensional maxillary dental casts were analyzed; 20 at the beginning of treatment, 20 after distalization, 20 after edgewise appliance debonding, and 20 at 5 years posttreatment. Maxillary transverse distances between canines, first premolars, second premolars, first molars, and second molars were analyzed using Geomagic Studio 5 (3D Systems, Rock Hill, SC).

RESULTS

There were no significant changes in intercanine distance during and after treatment. There were significant interfirst and intersecond premolar distance increases during treatment. There were significant interfirst and intersecond molar distance increases during the distalization phase. However, there were significant decreases in these distances at the end of treatment. There were no significant long-term posttreatment changes.

CONCLUSIONS

The intercanine distance remains stable during and after treatment. The interfirst and intersecond premolar distances significantly increase during treatment and remain stable after treatment. The interfirst and intersecond molar distances increase during the distalization phase, decrease at the end of treatment, and remain stable after treatment.

Inter-premolar width changes related to the orthodontic traction of maxillary impacted canines in adolescents and young adults: A retrospective CBCT study

OBJECTIVE

Maxillary canine impaction is directly associated with a narrow maxillary arch, mainly in the inter-premolar widths. This study compared the transverse changes at the level of maxillary premolars after traction of maxillary impacted canines (MICs) in adolescents and young adults through three main goals: to compare unilateral versus bilateral cases, to compare buccally versus palatally MIC cases, and to compare the affected versus non-affected side exclusively in the unilateral group.

METHODS

This before and after CBCT study involved 45 MIC orthodontically tractioned until the occlusal plane with a standardized protocol. The sample was classified regarding the impaction type (unilateral versus bilateral), impaction location (palatal versus buccal) and the affected versus unaffected sides in the unilateral cases. MIC characteristics as impaction sector, height, and complexity of the traction, as well as α and β angles, canine root length and area were measured. Moreover, cephalometric characteristics were also evaluated. Mann-Whitney U or Wilcoxon signed-rank tests and multiple regressions were applied (α=0.05).

RESULTS

Maxillary inter-premolar widths (first or second) expanded approximately 3mm after traction of unilateral or bilateral MIC (P>0.05). Changes in hemi-arch widths between palatal (1.67mm) versus buccal (1.90mm) MIC were similar (P>0.05). In unilateral impaction, the transversal changes on the affected side were 2mm versus almost 1mm observed in the unaffected side (P<0.05). Finally, the multiple linear regressions were identified to the ANB angle, the impaction sectors and the distance from middle raphe to the cusp tip of MIC as influential variables.

CONCLUSION

The maxillary inter-premolar widths increase after traction of MIC without differences between type or location of impaction. In addition, the transverse change in the affected side in unilateral MIC is greater than the unaffected side resolving the earlier transverse asymmetry.

Dental and skeletal changes associated with the Damon system philosophical approach

OBJECTIVE

To compare the skeletal and dentoalveolar changes produced by the Damon system's treatment philosophy to traditional orthodontic treatment techniques.

MATERIALS AND METHODS

An electronic search in four major databases was completed: Cochrane, PubMed, EMBASE, and Google Beta Scholar on October 5th, 2018. Randomized controlled trials, prospective and retrospective controlled clinical trials were included in this systematic review. The quality assessment of individual studies was done using two different tools: The Cochrane Risk of Bias Assessment Tool (RTCs) and The Methodological Index for Non-Randomized Studies (MINORS) (non-RCTs).

RESULTS

Seven studies were included for this qualitative analysis. Six studies compared the Damon system to various types of conventional (non self-ligating bracket) system as a comparison group. One study used a quad helix as a comparison for a few months before a full bonding appointment with conventional brackets. The majority of studies found an increase in maxillary inter-canine, inter-premolar, and intermolar distance after the treatment in both the Damon and comparison groups. Yet, all studies concluded that there is no significant difference in the final transverse dimension between the two groups. One study also found that the transverse expansion was achieved mainly by tipping movement of posterior dentition, and a decrease in the posterior buccal bone area was evident in both groups after treatment.

CONCLUSION

There is not enough evidence to support the claim that the Damon system allows additional arch expansion with better tipping control than with traditional techniques.

Comparison of transverse maxillary dental arch width changes with self-ligating and conventional brackets in patients requiring premolar extraction - A randomised clinical trial

OBJECTIVE

The purpose of this study was to evaluate, the change in the transverse maxillary arch dimensions, in patients requiring all first premolar extractions when using Active and Passive Self-ligating brackets, and comparing them with Conventional brackets.

MATERIALS AND METHODS

This study was a non-blinded randomised clinical trial, which consisted of 42 patients (21 males and 21 females) within the age group of 16-25 years, having bimaxillary protrusion. They were divided into three groups with 14 patients each. In Group 1 - Conventional brackets (3M Unitek), in Group 2 - Passive Self-ligation brackets: Smart Clip (3M Unitek), and in Group 3 - Active Self-ligation brackets: Empower AO (American Orthodontics) were bonded. All brackets had MBT prescription and 0.02" slot size. Dental study models were taken before the start of treatment and after six months of retraction. Inter-canine and intermolar widths were measured in all the three groups in the above mentioned stages.

RESULTS

As compared to Conventional brackets, Self-ligating brackets (Passive and Active) showed greater increase in the transverse arch widths. Furthermore, between Passive and Active Self-ligating brackets, Passive Self-ligating brackets - Smart Clip (Group 2) showed a greater increment in the transverse arch dimensions, with an increase of 4.89mm in the inter-canine width and 3.4mm in intermolar width.

CONCLUSION

Significant difference was found between Self-ligating brackets and the Conventional bracket system regarding maxillary arch width dimensional changes. Passive Self-ligating brackets - Smart Clip (Group 2) showed the highest and inter-molar width increase.

Agreement of the clinician's choice of archwire selection on conventional and virtual models

OBJECTIVES

To compare archwire selection on dental casts with archwire selection using a three-dimensional (3D) software program (OrthoAid) and assess agreement between clinicians.

MATERIALS AND METHODS

The best-fitting archwires were selected for dental casts of 100 patients with malocclusion using two approaches by three orthodontists. The first method was to visually determine the fitness of five preformed nickel titanium archwires to the arch form on a dental cast (subjective method). The second method was archwire selection on a virtual image of the same cast by means of 3D software (objective method). Agreement between selections performed by the orthodontists was calculated using Kappa statistics. The accuracy of fit of the archwires to the curves fitted to the arch form was also calculated or reversely assessed by means of the root mean square (RMS) for both methods using the Dahlberg formula.

RESULTS

The mean RMS of the distances between the patient arch forms and the archwires for the subjective method was 1.163-1.366 mm. The agreement of selections between orthodontists was 42%-58% (Kappa ranged from .074 to .382). Using the 3D software (objective method), the mean RMS decreased to 0.966-1.171 mm, and agreement increased to 47% to 84% (Kappa ranged from .444 to .747).

CONCLUSIONS

The use of 3D computer software for archwire selection in patients with malocclusion provided better adaptation and interexaminer reliability.

Dental inclination with self-ligating and conventional fixed appliances, with and without rapid maxillary expansion

OBJECTIVE

To compare the labio- and buccolingual inclination of the anterior and posterior teeth in subjects treated with self-ligating and conventional fixed appliances with and without rapid maxillary expansion.

METHODS

Seventy-one subjects with Class I malocclusion were divided into three groups. Group 1 comprised 24 subjects (17 female; seven male, with a mean age of 13.94 ± 2.87 years), treated with Roth's pre-adjusted fixed appliances. Group 2 comprised 24 subjects (14 female; 10 male, with a mean age of 13.85 ± 1.83 years) treated with Rapid Maxillary Expansion followed by Roth's pre-adjusted fixed appliances. Group 3 comprised 23 patients (12 female; 11 male, with a mean age of 14.75 ± 1.34 years) treated with Damon self-ligating bracket system. Buccolingual inclination was measured on digital dental models using a 3D software. Intergroup changes comparison was performed with one-way ANOVA, followed by Tukey tests.

RESULTS

The left maxillary lateral incisor showed labial inclination in the conventional and RME groups, and palatal inclination in the Damon group. The Damon group showed greater buccal inclination in most posterior mandibular teeth during treatment than the conventional and RME groups. The right mandibular canine and lateral incisor showed greater labial inclination in the Damon group than in the RME group.

CONCLUSIONS

There was greater buccal inclination of the posterior mandibular teeth and labial inclination of the right mandibular canine and lateral incisor in the Damon group.

Photoelastic analysis of stress distributions in the root-bone interface when applying various orthodontic methods to subside lower anterior crowding

Dental crowding is a prevalent problem in modern society. Various factors, including different bracket systems and geometry of wire, influence the outcome using superelastic wire in the alignment stage of treatment. Currently, the use of light round wire instead of large-sized rectangular wire is emphasized to avoid powerful torsional stiffness. However, these guidelines lack scientific evidence for support. They have been written predominantly based on clinical experience. Therefore, the purpose of this study was to evaluate how factors such as bracket systems and wire geometry affect the stress distribution at the root-bone interface. Models using a photoelastic material (PL-3) to simulate bone tissue were fabricated. The simulated teeth were arranged as in lower anterior crowding. Then, the crowded teeth were subjected to orthodontic treatment with various types of bracket, ligating approaches using ligature wires of different sizes, shapes, and materials. Photoelastic images of the bone area of the models were obtained and compared. The results showed that wire size plays a more significant role than the material or cross-sectional shape of the wire in affecting the stress distribution at the simulated root-bone interface. The teeth ligated with a larger cross-sectional diameter of wire showed the application of excessive torque, which may cause root resorption and slow down tooth movement. These results not only demonstrate the scientific evidence backing clinical experience but also can be a useful reference for further clinical application.

Evaluation of lower anterior dental changes in patients treated with self-ligating brackets

The aim of this study was to evaluate and compare changes in linear distance and inclination of lower incisors and canines and intercanine distance after a 30 months orthodontic treatment with self-ligating appliances. Seven patients were treated orthodontically with a Roth prescription passive self-ligating bracket. To perform the measurements and comparisons, CBCT scans were taken before the start of the orthodontic treatment (T₁) and after a period of 30 months treatment (T₂). The following measurements were performed: (1) the lower incisors and canines inclination in relation to the mandibular plane, (2) intercanine linear distance in millimeters and (3) linear distance in millimeters of the incisal and apical part of lower anterior teeth to a plane (POGM) passing through pogonion point and perpendicular to the mandibular plane. No significant difference were observed between T₁ and T₂ for canine inclination (p = 0.835), incisors inclination (p = 0.149), canine incisal distance to POGM (p = 0.423) and incisors incisal distance to POGM (p = 0.966), however canine apical distance (p = 0.049) and incisors apical distance (p = 0.002) to POGM was lower at T₁ than at T₂. The intercanine distance was significantly lower (p = 0.022) at T₁ when compared to T_2. The use of passive self-ligating brackets in orthodontic treatment to solve 4 mm tooth crowding were able to produce dental arch expansion by bodily tooth movement.

Evaluation of maxillary buccal alveolar bone before and after orthodontic alignment without extractions: A cone beam computed tomographic study

OBJECTIVES:

To assess the changes in the maxillary buccal alveolar bone during alignment without extractions. Secondarily, to evaluate the changes in arch dimensions and buccolingual inclinations of teeth and to identify risk factors for bone loss.

MATERIALS AND METHODS:

Twenty-two adolescents with crowded permanent dentitions were treated without extractions with Damon 3MX brackets. Cone beam computed tomographic scans were taken before treatment (T0) and after alignment (T1). Bone thickness (BT) and height from the cementoenamel junction to the alveolar crest (BH) were evaluated at the maxillary central incisors, second premolars, and buccal roots of first molars. Changes in all variables from T0 to T1 were assessed. Correlations between bone changes and initial bone thickness, initial arch widths, initial crowding, amount of expansion, amount of tipping, and amount of molar rotation were calculated.

RESULTS:

BT decreased and BH increased significantly for the incisors and mesiobuccal root of the first molars. Arch dimensions generally increased together with tipping. Bone loss was correlated with crowding and amount of expansion in the premolar region. Initially thinner BT was correlated with greater apical migration of bone for the incisors.

CONCLUSIONS:

Nonextraction alignment with self-ligating brackets led to arch expansion associated with tipping of teeth. Expansion related to alignment resulted in horizontal and vertical bone loss at the incisors and mesiobuccal root of the first molars. Thinner BTs and more severe crowding before treatment increased the risk for buccal bone loss.