Anin vitrostudy into the efficacy of complex tooth alignment with conventional and self-ligating brackets

Change in crown inclination accompanying initial tooth alignment with round archwires

OBJECTIVE

To evaluate, in-vitro, the change in crown inclination that occurs during orthodontic leveling and alignment using different archwire-bracket-ligation combinations.

MATERIALS AND METHODS

Four archwire types were tested: (1) 0.012-in stainless steel and (2) 0.0155-in stainless steel multi-stranded, (3) 0.012-in nitinol Orthonol® and (4) 0.012-in nitinol Thermalloy®. Combinations with five types of 0.022-in slot orthodontic brackets were tested: SmartClipTM and Time3® self-ligating brackets, Mini-Taurus® and Victory SeriesTM conventional brackets, and Synergy® conventional-low friction bracket. Conventional brackets were ligated with both stainless steel and elastomeric ligatures. The simulated malocclusion comprised 2.0mm gingival and 2.0mm labial displacements of a maxillary right central incisor. Rotation around the Y-axis (representing labio-palatal inclination) was measured for the different archwire-bracket-ligation combinations.

RESULTS

The largest rotation was measured whith Orthonol® and Thermalloy® wires when combined with SmartClipTM brackets (8.07±0.24º and 8.06±0.26º, respectively) and with Synergy® brackets ligated with stainless steel ligatures (8.03±0.49º and 8.0±0.37º, respectively). The lower rotation was recorded when Thermalloy®, multi-stranded, and Orthonol® wires were ligated with elastomeric rings to Mini-Taurus® brackets (1.53±0.18º, 1.65± 0.23º and 1.70±0.28º, respectively) and to Victory SeriesTM brackets (1.68± 0.78º, 2.92± 1.40º and 1.74±0.46º, respectively).

CONCLUSIONS

All archwire-bracket-ligation combinations produced lingual crown inclination; however, lower changes were observed when the conventional brackets were ligated with elastomeric rings. The multi-stranded archwire produced less rotation with nearly every bracket-ligation combination, compared to the other archwires. The effect of the archwire-bracket-ligation combination on tooth inclination during leveling and alignment should be considered during planning treatment mechanics.

Comparison of the friction forces delivered by different elastomeric patterns and metal ligature on conventional metal brackets with a NiTi arch wire versus a self-ligating system: An in vitro study

OBJECTIVES

The aim of this study was to measure the frictional resistance of different types of ligatures used on conventional and self-ligating brackets.

MATERIALS AND METHODS

Monoblock (conventional) and Portia (self-ligating) brackets were used and the archwire used was nickel-titanium. On conventional brackets the ligatures tested were the Elastomeric type and steel 0.30 tie-wire. The groups were divided according to the ligature types (n=8): (1) conventional elastomeric ligature; (2) relaxed conventional elastomeric ligature; (3) elastomeric ligature in shape-8; (4) double vertical elastomeric ligatures; (5) double-crossed elastomeric ligatures; (6) crossed ligature; (7) steel wire ligature; and (8) self-ligating ligature (self-ligating bracket). A segment of five brackets, each ligature types, was mounted. The archwire, between the bracket and the ligature, was connected on Instron® Universal test machine to simulate the frictional resistance. The maximum frictional resistance was obtained, and the mean values were submitted to the analysis of variance (ANOVA) and the Tukey's post-hoc test (α=0.05).

RESULTS

The elastomeric ligature in shape-8 showed the highest value compared with other groups (P<0.05). Although the crossed elastomeric ligature presented the lowest mean value and it was not statistically different regarding relaxed conventional elastomeric ligature, steel wire ligature and self-ligating (P≥0.05).

CONCLUSIONS

The frictional resistance was influenced by ligature types. Elastomeric Ligature in shape-8 showed the highest frictional force. Crossed Elastomeric Ligature had the lowest frictional force value.

Customized lingual brackets vs. conventional labial brackets for initial alignment : A randomized clinical trial

PURPOSE

The aim of this randomized prospective clinical study was to determine whether there are differences between customized lingual brackets and conventional labial brackets regarding the alignment of the mandibular arch and a reduction of the irregularity index during an 18-week treatment interval.

METHODS

A total of 20 patients who presented with class I malocclusion for scheduled orthodontic treatment without tooth extraction were included. The patients were randomly assigned by numbered, opaque, sealed envelopes to treatment with customized lingual brackets or conventional labial brackets. During the initial alignment (T0), 0.012″ (T1), 0.014″ (T2), and 0.016″ (T3) nickel-titanium archwires were applied, respectively, and the control visits were scheduled at 6‑week intervals. In all sessions, digital models were obtained by an intraoral scanning device after removal of the archwire and were analyzed by software. Little's irregularity index, intercanine width, intermolar width and arch length were evaluated at three time points and were statistically analyzed with a repeated measures analysis of variance (ANOVA). Changes in these measurements at the three intervals (T1-T0, T2-T1, T3-T2) and overall treatment effects were also compared using the Student t‑test.

RESULTS

Comparing the two treatments regimes, intergroup mean values at T0, T1, T2, and T3 were not significantly different regarding the irregularity index, intercanine width, intermolar width and arch length.

CONCLUSION

In this pilot study, no differences between the two treatment approaches could be detected for the phase of initial mandibular alignment.

Influence of a Lubricating Gel (Orthospeed®) on Pain and Oral Health-Related Quality of Life in Orthodontic Patients during Initial Therapy with Conventional and Low-Friction Brackets: A Prospective Randomized Clinical Trial

The aim of this study was to investigate whether statistically significant differences exist regarding pain and the impact on oral quality of life of orthodontic treatment. A conventional brackets system was compared with low-friction brackets. A total of 90 patients (male = 35, female = 55) were chosen for this randomized clinical trial. Pain was assessed at 4, 8, and 24 hours and 2, 3, 4, 5, 6, and 7 days after the start of treatment using the McGill Pain Questionnaire. Oral health-related quality of life (OHRQoL) was assessed using the Oral Health Impact Profile-14 (OHIP-14) questionnaire. Oral quality of life was assessed at one month, with patients with low-friction brackets describing lower levels of pain. The patients with conventional brackets indicated a worse impact on their quality of life compared to the group with low-friction brackets. Statistically significant differences were found between the groups, with maximum pain observed between the first 24 and 48 hours, and the values of minimum pain are reached after 7 days. The pain and impact on oral quality of life was statistically worse in patients with conventional brackets compared to patients with low-friction brackets. The type of bracket system used was therefore shown to influence patients' perceptions of pain and impact on their OHRQoL.

Incorrect measurements and misleading conclusions in the article "Comparison of the efficacy of tooth alignment among lingual and labial brackets: an in vitro study"

Background/objective

To reproduce the methods and results of the study by Alobeid et al. (2018) in which the efficacy of tooth alignment using conventional labial and lingual orthodontic bracket systems was assessed.

Materials/methods

We used the identical experimental protocol and tested (i) regular twin bracket (GAC-Twin [Dentsply]) and lingual twin bracket systems (Incognito [3M]), (ii) together with NiTi 0.014” wires (RMO), and (iii) a simulated malocclusion with a displaced maxillary central incisor in the x-axis (2 mm gingivally) and in the z-axis (2 mm labially).

Results

The method described by Alobeid et al. (2018) is not reproducible, and cannot be used to assess the efficacy of tooth alignment in labial or lingual orthodontic treatment. Major flaws concern the anteroposterior return of the Thermaloy-NiTi wire ligated with stainless steel ligatures. The reproduced experimental setting showed that a deflected Thermaloy-NiTi wire DOES NOT move back at all to its initial stage (= 0 per cent correction) because of friction and binding (see supplemented video), neither with the tested labial nor with the lingual brackets. Furthermore, an overcorrection of up to 138 per cent, which the authors indicate for some labial bracket-wire combinations and which deserves the characterization “irreal”, stresses the inappropriateness of the method of measurement.Further flaws include: a) incorrect interpretation of the measurement results, where a tooth tripping around (overcorrection) is interpreted as a better outcome than a perfect 100 per cent correction; b) using a statistical test in an inappropriate and misleading way; c) uncritical copying of text passages from older publications to describe the method, which do not correspond to this experimental protocol and lead to calculation errors; d) wrong citations; e)differences in table and bar graph values of the same variable; f) using a lingual mushroom shaped 0.013” Thermaloy-NiTi wire which does not exist; g) drawing uncritical conclusions of so called "clinical relevance" from a very limited in vitro testing.

Conclusions

Clinical recommendations based on in vitro measurements using the Orthodontic Measurement and Simulation System (OMSS) should be read with caution.

Comparison of the efficacy of tooth alignment among lingual and labial brackets: an in vitro study

Background/objective

The aim of this study was to evaluate the efficacy of tooth alignment with conventional and self-ligating labial and lingual orthodontic bracket systems.

Materials/methods

We tested labial brackets (0.022″ slot size) and lingual brackets (0.018″ slot size). The labial brackets were: (i) regular twin brackets (GAC-Twin [Dentsply]), (ii) passive self-ligating brackets including (Damon-Q® [ORMCO]; Ortho classic H4™ [Orthoclassic]; FLI®SL [RMO]), and (iii) active self-ligating brackets (GAC In-Ovation®C [DENTSPLY] and SPEED™[Strite]). The lingual brackets included (i) twin bracket systems (Incognito [3M] and Joy™ [Adenta]), (ii) passive self-ligating bracket system (GAC In-Ovation®LM™ [Dentsply]), and (iii) active self-ligating bracket system (Evolution SLT [Adenta]). The tested wires were Thermalloy-NiTi 0.013″ and 0.014″ (RMO). The archwires were tied to the regular twin brackets with stainless steel ligatures 0.010″ (RMO). The malocclusion simulated a displaced maxillary central incisor in the x-axis (2 mm gingivally) and in the z-axis (2 mm labially).

Results

The results showed that lingual brackets are less efficient in aligning teeth when compared with labial brackets in general. The vertical correction achieved by labial bracket systems ranged from 72 to 95 per cent with 13″ Thermalloy wires and from 70 to 87 per cent with 14″ Thermalloy wires. In contrast, the achieved corrections by lingual brackets with 13″ Thermalloy wires ranged between 25-44 per cent and 29-52 per cent for the 14" Thermalloy wires. The anteroposterior correction achieved by labial brackets ranged between 83 and 138 per cent for the 13″ Thermalloy and between 82 and 129 per cent for the 14″ Thermalloy wires. On the other hand, lingual brackets corrections ranged between 12 and 40 per cent for the 13″ Thermalloy wires and between 30 and 45 per cent for the 14″ Thermalloy wires.

Limitation

This is a lab-based study with different labial and lingual bracket slot sizes (however they are the commonly used ones in clinical orthodontics) and study did not consider saliva, periodontal ligament, mastication and other oral functions.

Conclusions

The effectiveness of lingual brackets in correcting vertical and anteroposterior displacement achieved during the initial alignment phase of orthodontic treatment is lower than that of the effectiveness of labial brackets.

Archwire diameter effect on tooth alignment with different bracket-archwire combinations

INTRODUCTION

Our objective was to evaluate the effect of the diameter of the archwire on tooth alignment with different bracket-archwire combinations.

METHODS

The materials included 2 categories of orthodontic brackets (1) conventional ligating brackets (Victory Series [3M Unitek, Monrovia, Calif], Mini-Taurus [Rocky Mountain Orthodontics, Denver, Colo], and Synergy [Rocky Mountain Orthodontics]) and (2) self-ligating brackets (SmartClip [3M Unitek], a passive self-ligating bracket; Time3 [American Orthodontics, Sheboygan, Wis], an active self-ligating bracket; and SPEED [Strite Industries, Cambridge, Ontario, Canada], an active self-ligating bracket). All brackets had a nominal 0.022-in slot size. The brackets were combined with Therma-Ti 0.014-in and Therma-Ti 0.016-in titanium memory archwires (American Orthodontics). The archwires were tied to the conventional brackets with both stainless steel ligatures (0.010 in) and elastomeric rings. Each bracket-archwire combination was tested 20 times with the orthodontic measurement and simulation system built in a temperature-controlled chamber where the temperature was kept at 37°C (±1°C) during testing. The malocclusion simulated in the study represented a maxillary central incisor displaced 2 mm gingivally (x-axis) and 2 mm labially (z-axis).

RESULTS

The incisogingival corrections achieved by the 0.014-in archwire combined with the brackets used ranged from 40% to 95%; the corrections by the 0.016-in wire were 55% to 95%. The labiolingual corrections achieved by the 0.014-in archwire combined with the brackets used ranged from 10% to 100%, and the corrections of the 0.016-in archwires ranged from 15% to 100%.

CONCLUSIONS

Increasing the diameter from 0.014 to 0.016 in increased the correction achieved by up to 15% in certain bracket-archwire combinations, but it decreased the correction by up to 25% in other combinations.