Root resorption after leveling with super-elastic and conventional steel arch wires: a prospective study

Alignment efficiency and three-dimensional assessment of root resorption after alignment with conventional and copper-nickel-titanium archwires: A randomized controlled trial

OBJECTIVE

To compare alignment efficiency and root resorption between nickel-titanium (NiTi) and copper-nickel-titanium (CuNiTi) archwires after complete alignment in mandibular anterior region.

METHODS

In this two-arm parallel single-blind randomized controlled trial, forty-four patients with Class I malocclusion with mandibular anterior crowding were recruited form orthodontic clinic of All India Institute of Medical Sciences (Jodhpur, India). Patients were randomly allocated into NiTi and CuNiTi groups, with a 1:1 allocation. Alignment was performed using 0.014-in, 0.016-in, 0.018-in, 0.019x0.025-in archwire sequence in the respective groups, which terminated in 0.019 x 0.025-in stainless-steel working archwire. The primary outcome was alignment efficiency, measured on study models from baseline (T0) to the first, second, third, fourth and fifth-month (T5). Secondary outcome was root resorption, measured from CBCT scans taken at T0 and T5. Mixed-factorial ANOVA was used to compare Little's Irregularity Index (LII). For assessing the proportion of patients with complete alignment at the end of each month, Kaplan-Meier survival curve was built and time to treatment completion was compared between groups using log rank test. Paired t-test was used to assess external apical root resorption (EARR) within groups, whereas independent t-test was used to evaluate LII and EARR between the groups.

RESULTS

Twenty-two patients were recruited in each group. One patient was lost to follow-up in the CuNiTi group. No statistically significant differences were observed in alignment efficiency between the groups (p>0.05). Intergroup comparison revealed that the changes in root measurement in three-dimensions were not statistically significant (p>0.05), except for mandibular right central incisor, which showed increased resorption at root apex in NiTi group (p<0.01).

CONCLUSION

The two alignment archwires showed similar rate of alignment at all time points. Root resorption measurement did not differ between the NiTi and CuNiTi groups, except for the mandibular right central incisor, which showed more resorption in NiTi group.

Thermal Programming of Commercially Available Orthodontic NiTi Archwires

The shape of superelastic Nickel-Titanium (NiTi) archwires can be adjusted with thermal treatments using devices such as the Memory-Maker^TM (Forestadent), which potentially affects their mechanical properties. The effect of such treatments on these mechanical properties was simulated by means of a laboratory furnace. Fourteen commercially available NiTi wires (0.018″ × 0.025″) were selected from the manufacturers American Orthodontics, Dentaurum, Forestadent, GAC, Ormco, Rocky Mountain Orthodontics and 3M Unitek. Specimens were heat treated using different combinations of annealing duration (1/5/10 min) and annealing temperature (250-800 °C) and investigated using angle measurements and three-point bending tests. Complete shape adaptation was found at distinct annealing durations/temperatures for each wire ranging between ~650-750 °C (1 min), ~550-700 °C (5 min) and ~450-650 °C (10 min), followed by a loss of superelastic properties shortly afterwards at ~750 °C (1 min), ~600-650 °C (5 min) and ~550-600 °C (10 min). Wire-specific working ranges (complete shaping without loss of superelasticity) were defined and a numerical score (e.g., stable forces) was developed for the three-point bending test. Overall, the wires Titanol Superelastic (Forestadent), Tensic (Dentaurum), FLI CuNiTi²⁷ (Rocky Mountain Orthodontics) and Nitinol Classic (3M Unitek) proved to be the most user-friendly. Thermal shape adjustment requires wire-specific working ranges to allow complete shape acceptance and high scores in bending test performance to ensure permanence of the superelastic behaviour.

Orthodontic root resorption

External apical root resorption (EARR) is one of the most frequently reported iatrogenic side effects of orthodontic movement. Nevertheless, no robust and unequivocal scientific evidence is yet available in the literature regarding the clinical and biological factors that trigger EARR. The purpose of the present position paper is to provide clinicians, residents, and investigators a summary of our current understanding about root resorption caused by orthodontic tooth movement, based on up-to-date available scientific evidence. Morphological, structural, biomechanical, and biological differences account for predisposing the apical third to EARR compared to other root surfaces during orthodontic treatment. In addition, a relevant number of patient and treatment-related factors increase risk of EARR. The main patient-related factors are reviewed and discussed: genetic factors, tooth anatomy, demographic factors, malocclusion factors, previous endodontic treatment, medical history, short root anomaly. Similarly, the influence of treatment-related factors are analyzed with regard to the effect of: biomechanical factors, type of orthodontic appliance, adjunctive therapies to accelerate tooth movement, early treatment, maxillary expansion, teeth extractions, the duration of treatment and the amount of apical displacement. Clinical management of EARR from pre-treatment records to the monitoring strategy as well as recommendations for the post orthodontic-treatment period are presented as a guide for the clinician. Despite years of studies, we still do not fully understand EARR, but the future is promising. True three-dimensional imaging with higher resolution and low radiation, and predictive tools towards an earlier detection without radiographs, will mark future developments in the field of EARR in orthodontics.

Comparison of two different initial archwires for tooth alignment during fixed orthodontic treatment-A randomized clinical trial

OBJECTIVES:

The aim of the study was to clinically evaluate and compare 0.016-inch superelastic nickel–titanium (NiTi) and 0.016-inch heat-activated nickel–titanium (NiTi) archwires in terms of alignment efficiency, root resorption, and pain intensity.

METHOD:

A total of 20 patients requiring fixed orthodontic treatment, having Little's irregularity index of 5–8, and requiring first premolar extractions were recruited. They were randomly allocated to receive two different archwires (0.016-inch superelastic NiTi or 0.016-inch thermoelastic NiTi). Good-quality impressions were taken of the lower arch before archwire placement (T0) and at every month after that till the alignment was complete. The rate of tooth alignment was measured on casts by determining Little's irregularity index. The pain experienced by the patient was assessed 24 hours and 1 week after the placement of the archwire on a visual analogue scale. Cone beam computed tomographic radiographs of lower anterior teeth were taken before and after alignment to assess root resorption. Data obtained were subjected to statistical analysis using the SPSS software (version 20.0). The level of significance was kept at 5%.

RESULTS:

The repeated measures ANOVA indicated that there was no significant difference in the aligning efficiency of superelastic and heat-activated NiTi wires. (p = 0.45). The Mann Whitney U test showed that superelastic NiTi wires had statistically significant higher VAS scores than heat-activated NiTi at 24 hours and 1-week interval (p < 0.05). Student's t-test indicated greater root resorption with superelastic NiTi but the difference was not statistically significant.

CONCLUSION:

Both the wires showed similar aligning efficiency and resulting root resorption. Superelastic NiTi was observed to produce more pain compared to heat-activated NiTi in the aligning phase.

A clinical comparison of the effectiveness of two types of orthodontic aligning archwire materials: a multicentre randomized clinical trial

OBJECTIVES

To compare the heat-activated nickel titanium (HANT) with superelastic nickel-titanium (SENT) archwires in terms of their effectiveness of aligning teeth, possibility of inducing root resorption, and perception of pain.

SUBJECTS AND METHODS

Orthodontic patients aged 12 years or over with mandibular anterior crowding of 3-6 mm, who required treatment without extractions were randomly allocated (a simple non-stratified randomization) to the HANT and SENT archwires groups with a 1:1 allocation ratio. The archwire sequence in both groups was 0.014-inch and 0.016-inch, respectively. Each archwire was placed for 4 weeks. The outcome measures included the amount of crowding assessed blindly using Little's irregularity index (LII), apical root resorption, and pain perception. The effectiveness of alignment was tested using 2 × 2 mixed factorial analysis of variance (ANOVA) model, while root resorption and pain perception were tested by the Mann-Whitney U-test and Wilcoxon signed-rank test (P < 0.05).

RESULTS

Thirty-four patients were randomized and recruited from four centres, of those 31 were analysed (15 participants for the HANT and 16 for the SENT groups) with an overall mean age of 19.13 ± 5.73 years. The total reduction in the LII was 2.69 mm and 2.74 mm for the HANT and SENT groups, respectively. This did not reach the level of statistical (P = 0.809) or clinical significance. Similarly, root resorption and pain perception showed non-significant difference between groups. However, there was a slight increase in root resorption with the SENT group.

LIMITATIONS

A long-term evaluation of root resorption is required.

CONCLUSIONS

Both HANT and SENT archwires were equally effective in the aligning stage of orthodontic treatment. Root resorption with SENT wires should be monitored throughout treatment.

REGISTRATION

The trial was registered with ClinicalTrials.gov on 18 September 2019, registration number: NCT04090931.

Orthodontic treatment and root resorption: an overview of systematic reviews

BACKGROUND

Root resorption can be considered the most unfortunate complication of orthodontic treatment.

OBJECTIVE

To evaluate the available evidence regarding orthodontically induced inflammatory root resorption (OIIRR).

SEARCH METHODS

A comprehensive literature search was conducted for the systematic reviews investigating OIIRR published up to 24 May 2020. This was accomplished using electronic databases: MEDLINE via OVID, EMBASE, AMED (Allied and Complementary Medicine Database), PubMed, and Web of Science. Any ongoing systematic reviews were searched using Prospero and a grey literature search was undertaken using Google Scholar and OpenGrey (www.opengrey.eu/). No language restriction was applied.

SELECTION CRITERIA

Only studies investigating OIIRR were included.

DATA COLLECTION AND ANALYSIS

Screening, quality assessment [using the AMSTAR 2 tool (A Measurement Tool to Assess Systematic Reviews)], and data extraction were performed by two authors independently. Information was categorized and narratively synthesized for the key findings from moderate and high-quality reviews.

RESULTS

A total of 2033 potentially eligible studies were identified. After excluding the non-relevant studies, 28 systematic reviews were included. Of which, 20 systematic reviews (71.5%) were of moderate and high-quality level of evidence. The incidence and severity of OIIRR increase with the fixed appliance, especially with heavy force, intrusion, torqueing movements, increased treatment duration, and treatment with extractions or with long apical displacement (particularly for maxillary incisors). There was insufficient evidence regarding most other treatment- and patient-related factors on OIIRR. Following all precautionary measures, pausing treatment and regular monitoring benefits patients with OIIRR.

CONCLUSIONS AND IMPLICATIONS

There is a limited number of high-quality studies in terms of OIIRR. The influence of fixed appliance on root resorption was noted; however, the cause and effect relationship between OIIRR and orthodontic biomechanics has not been confirmed. Avoiding heavy, continuous forces and a greater amount of apical displacement over a long duration of treatment is recommended. Precautionary measures should be carefully considered when treating patients with a high risk of OIIRR.

REGISTRATION

CRD42020166629.

Apical root resorption after orthodontic treatment in patients with unilateral cleft lip and palate

OBJECTIVES

The aims of this retrospective longitudinal study were to present the incidence of external apical root resorption (EARR) in the maxillary anterior teeth of patients with complete unilateral cleft lip and palate (CUCLP) and to evaluate the influence of orthodontic treatment variables on the development of EARR.

MATERIAL AND METHODS

Forty-one patients with CUCLP participated in the study. Orthopantomograms (OPGs), taken before (T2) treatment with multiband orthodontic appliances (MBA), and periapical radiographs (PAs) of the maxillary anterior teeth taken at the end (T3) of orthodontic treatment (OT) were assessed for EARR.

RESULTS

The incidence of EARR at T3 (97.6%) was considerably higher than at T2 (51.2%). Central incisors and canines on the cleft side showed a significantly higher score (p < 0.01, p < 0.05 respectively) of EARR in comparison to the same group of teeth on the non-cleft side. Preexisting EARR and abnormal root morphology were identified as predisposing factors for EARR.

CONCLUSIONS

Patients with CUCLP treated with MBA have higher incidence of EARR on the maxillary anterior teeth of the cleft side. Severe EARR is rather rare but more often seen on central incisors of the cleft side.

CLINICAL RELEVANCE

As most of the patients with cleft lip and palate undergo a challenging and long-term OT with MBA, it is of importance to identify the predisposing factors related to the special anatomical features of the bone and teeth located in the cleft area, as well as the special OT needs of these patients.

Orthodontic mechanotherapies and their influence on external root resorption: A systematic review

INTRODUCTION

This systematic review assesses the literature regarding the association between orthodontic tooth movement and external root resorption. By determining the evidence level supporting the association, the results could provide clinical evidence for minimizing the deleterious effect of orthodontic tooth movement.

METHODS

Electronic databases, including MEDLINE, PubMed, Embase, Scopus, CINAHL, Cochrane Library, and LILACS, were searched up to February 2018, with hand searching of selected orthodontic journals undertaken to identify any preelectronic publications. Searches were undertaken with no restrictions on year, publication status, or language. Selection criteria included randomized controlled trials conducted with the use of fixed orthodontic appliances or sequential thermoplastic aligners on human patients. The quality of included studies was assessed with the use of the Cochrane Risk of Bias Tool and the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. Inter-rater agreement of the review authors was used for the inclusion of primary articles, risk of bias assessment, and evaluation of the quality of evidence (GRADE), and it was calculated with the use of the Cohen kappa statistic.

RESULTS

A total of 654 articles were retrieved in the initial search. After the review process, 25 articles describing 24 individual trials met the inclusion criteria. Sample sizes ranged from 6 to 154 patients. Most articles were classified as having unclear risks of bias and very low to low quality of evidence.

CONCLUSIONS

There is very low to low evidence for supporting positive associations between root resorption and increased force levels, force continuity, intrusive forces, and treatment duration. Moreover, by including a pause in treatment for patients experiencing root resorption, it may be possible for the clinician to reduce the severity of the condition. Of the included studies, the most common methodologic flaws include the absence of a control group, appropriate randomization strategy, and adequate examinations before and after treatment.

The effect of mechanical vibration on orthodontically induced root resorption

OBJECTIVE

To investigate the effect of low-frequency mechanical vibration (LFMV) on orthodontically induced root resorption.

MATERIALS AND METHODS

Forty male CD1, 12-week-old mice were used for the study. The mice were randomly divided into five groups: group 1 (baseline)-no spring and no mechanical vibration, group 2-orthodontic spring but no vibration, group 3-orthodontic spring and 5 Hz of vibration applied to the maxillary first molar, group 4-orthodontic spring and 10 Hz of vibration applied to maxillary first molar, and group 5-orthodontic spring and 20 Hz of vibration applied to maxillary first molar. In the different experimental groups, the first molar was moved mesially for 2 weeks using a nickel-titanium coil spring delivering 10 g of force. LFMVs were applied at 5 Hz, 10 Hz, and 20 Hz. Microfocus X-ray computed tomography imaging was used to analyze root resorption. Additionally, to understand the mechanism, we applied LFMV to MC3T3 cells, and gene expression analyses were done for receptor activator of nuclear factor kappa-B ligand (RANKL) and osteoprotegerin (OPG).

RESULTS

Orthodontic tooth movement leads to decreased root volume (increased root resorption craters). Our in vivo experiments showed a trend toward increase in root volume with different frequencies of mechanical vibration. In vitro gene expression analyses showed that with 20 Hz of mechanical vibration, there was a significant decrease in RANKL and a significant increase in OPG expression.

CONCLUSION

There was a trend toward decreased root resorption with different LFMVs (5 Hz, 10 Hz, and 20 Hz); however, it was not more statistically significant than the orthodontic-spring-only group.

External root resorption with the self-ligating Damon system-a retrospective study

Background

The aim of this study was to compare the degree of external apical root resorption (EARR) in patients treated with self-ligating Damon appliances and with conventional preadjusted appliances.

Methods

The sample comprised 52 patients, divided into two groups. Group 1 consisted of 25 patients treated with self-ligating Damon appliances, with an initial age of 16.04 years, final age of 18.06 years, and treatment time of 2.02 years. Group 2 consisted of 27 patients, treated with conventional preadjusted appliances, with an initial age of 16.77 years, final age of 18.47 years and treatment time of 1.70 years. The groups were matched regarding the initial and final ages, treatment time, type of malocclusion, and treatment protocol without extractions. Root resorption was evaluated on periapical radiographs of the maxillary and mandibular incisors at the end of orthodontic treatment with the scores of Levander and Malmgren. Intergroup comparisons of root resorption were performed with Mann-Whitney tests.

Results

No significant difference in the degree of root resorption between the two groups was found.

Conclusions

Similar degrees of resorption can be expected after non-extraction treatment with Damon self-ligating or conventional preadjusted appliances.