A comparative study of initial changes in pulpal blood flow between clear aligners and fixed orthodontic appliances

EFFECTIVENESS OF CLEAR ORTHODONTIC ALIGNERS IN CORRECTING MALOCCLUSIONS: A SYSTEMATIC REVIEW AND META-ANALYSIS

OBJECTIVE

The purpose of this research was to assess the effectiveness of clear aligners in treating various types of malocclusions when compared to fixed orthodontic appliances.

METHODS AND QUALITY

The following databases were searched: EMBASE (Ovid), Medline (Ovid), the Cochrane Library, Latin America and the Caribbean Literature on Health Sciences (Lilacs), Web of Science and EBMR review until October 2024. Additionally, Google scholar, PubMed were also searched for completion for including all relevant articles. No restrictions were placed on language or publication date, and only randomized controlled trials (RCTs) were included in this review. Evaluation of the potential for bias in randomized controlled trials (RCTs) was carried out with the use of the revised Cochrane Risk of Bias instrument (ROB tool 2). The primary outcome was the treatment accuracy of clear aligners vs fixed appliances and included orthodontic tooth movement in terms of anteroposterior discrepancy, transverse discrepancy, vertical discrepancy and overjet. The secondary outcomes included the effectiveness of treatment, such as duration of treatment, periodontal health, root resorption and patient satisfaction. Available data was meta-synthesized using Review Manager 5.4.

RESULTS

About 21 RCT studies were selected from a total of 600 records and involved 970 participants. All 21 studies included a comparison of the effectiveness of clear aligners vs fixed appliances. About 3 of the studies were assessed to be at high risk of bias, whilst 14 of the studies were assessed to be at unclear risk of bias, and only 1 study was found to be at low risk of bias. Based on the primary outcome, there was no significant difference in the ABO objective grading scores, Little Irregularity Index and PAR scores between the fixed appliances and clear aligner treatments. Meta-analysis was only possible for secondary outcomes. The scores for plaque index (MD = -0.76, 95% CI, -1.14 to - 0.38, P = .00001), gingival index (MD = -0.61, 95% CI, -0.78 to - 0.44, P = .00001) and bleeding index (MD = -0.71, 95% CI, -0.92 to - 0.49, P < .0001) were significantly lower in clear aligners when compared to the fixed appliances. The patients quality of life at 6 months was significantly better for clear aligners compared with fixed appliances (MD = -4.37, 95% CI, -6.93 to -1.80, P < .0001). Clear aligners also appeared to have a better outcome for chairside time, pain and root resorption.

CONCLUSION

The overall quality of evidence from the included studies was low. Both clear aligners and fixed appliances worked well in treating simple malocclusions treated on a nonextraction basis. There was no significant difference in the ABO Objective Grading System, Little Irregularity index and PAR scores between the clear aligner and fixed appliance groups. There was low quality evidence available in favor of clear aligners for periodontal health and moderate quality evidence in favor of clear aligners for quality of life. More high-quality studies evaluating clear aligner treatment for treating complex malocclusions are required.

Transient apical breakdown associated with clear aligner therapy: a case report

Transient apical breakdown (TAB) is widely reported in response to trauma, yet its occurrence due to orthodontic forces, particularly in aligner therapy, is less documented within current literature. TAB can easily be misdiagnosed as pulp necrosis, potentially leading to unnecessary and irreversible endodontic procedures. This case report describes an instance of TAB following the initiation of aligner treatment, where the affected tooth initially presented with signs suggesting pulp necrosis but regained normal coloration and pulpal response after six months of active monitoring. This case highlights the importance of raising awareness among dental practitioners, especially those providing aligner therapy, about the risk of TAB. This awareness is crucial given the increasing provision of aligner treatment in general practice settings and the associated medico-legal implications.

Evaluation of pulpal blood flow during orthodontic space closure: Prospective clinical trial

INTRODUCTION

Orthodontic tooth movement (OTM) is a biological process that can affect the vascularization of the dental pulp. The forces exerted on the teeth may increase periapical pressure that could compress the arterioles, which in turn affects pulpal blood flow (PBF). The study aimed to investigate how OTM affects PBF during orthodontic space closure.

METHODS

A total of 22 adolescent participants who required orthodontic space closure in mandibular posterior sectors were enrolled in a prospective clinical study. The same sliding mechanics, wires, and active elements were used. Patients were observed before OTM, after leveling before space closure, and at the 4th, 7th, 21st, and 28th during active space closure. PBF was measured with laser Doppler (LD) flowmetry. Dental models were obtained with an intraoral scanner.

RESULTS

The LD flow values decreased significantly during the observation period (2-way repeated measures analysis of variance, P <0.001). There was a significant difference in LD flow between tooth categories (2-way repeated measures analysis of variance, P <0.001). During space closure, the most pronounced LD flow reduction was observed in single-rooted teeth closest to the residual space. A higher speed of OTM was associated with a greater decrease in LD flow on day 4 of OTM (Pearson correlation, P = 0.0299).

CONCLUSIONS

Orthodontic space closure reduced PBF; it was lowest in the early stages of space closure and showed a tendency to increase during the first month. Anterior teeth closer to the interdental space that experiences more OTM and teeth that move faster during initial OTM had a higher risk of reduced blood flow.

The orthodontic-endodontic interface: trauma and pulpal considerations

The interpretation of the clinical signs and symptoms arising from the interdisciplinary relationship between orthodontics and endodontics becomes more complicated when superimposed by dental trauma. A history of dental trauma before or during orthodontic tooth movement may have implications for pulpal health and clinical outcomes. An understanding of the biology is essential for appropriate treatment planning. This review and treatment recommendations will assist dental practitioners in managing orthodontic-endodontic interactions.

Leveling the curve of Spee using different sized archwires: a randomized clinical trial of blood flow changes

OBJECTIVES

To compare blood flow (BF) changes of teeth subjected to orthodontic forces during curve of Spee (COS) leveling using different archwires (AW).

MATERIAL AND METHODS

Thirty subjects with COS > 5 mm were randomly assigned (1:1:1) into three groups based on the AW used: group 1: 0.017 × 0.025-inch stainless-steel (SS)AW, group 2: 0.019 × 0.025-inch SSAW, and group 3: 0.021 × 0.025-inch β-titanium (TMA)AW. In the 3 groups, a 5 mm-depth reverse COS was placed in the AWs. A laser Doppler flowmeter was used to measure BF at different time intervals (T0-T4).

RESULTS

In the 3 AWs group, BF of all measured teeth was reduced 20 min after force application. Afterwards, the BF values started to increase until the baseline values were almost restored within 1 week. Differences in BF changes between the extrusion and intrusion subgroups were observed within groups 1 and 3 during the first 20 min of force application (P < 0.05). Similar BF changes were recorded using the 3 different AWs. BF changes were associated with tooth type and the amount of COS depth change.

CONCLUSIONS

During CoS leveling, similar BF changes were recorded using the 3 different AWs. Tooth type and the amount of COS depth change were associated with BF changes within the first 20 min of force application. Greater BF reduction was found in premolars compared to incisors during the first 20 min of AW placement.

CLINICAL RELEVANCE

It is important to select a type of applied forces that minimally affect the BF. Intrusive forces appeared to have lower negative effects on the BF of teeth during COS leveling.

TRIAL REGISTRATION

ClinicalTrial.gov (# NCT04549948).

Endodontic-orthodontic interactions: a review and treatment recommendations

The literature is replete with articles describing the many and varied interactions between endodontic treatment and orthodontic tooth movement (OTM), often reporting conflicting views and findings, which creates confusion for clinicians. Original research and review articles have described aspects such as apical root resorption and potential pulpal complications of teeth related to OTM. Some interactions are of relatively minor clinical significance, whilst others may have adverse consequences. A history of dental trauma before or during OTM further complicates the interactions. This review re-assesses the historical literature on endodontic-orthodontic interactions in light of more recent research and presents guidelines for managing clinical situations involving both disciplines. © 2023 Australian Dental Association.

Adverse effects of orthodontic forces on dental pulp. Appearance and character. A systematic review

OBJECTIVE

To comprehensively assess recent data on the effects of orthodontic forces on the dental pulp and to critically evaluate, whether any of the changes are permanent.

MATERIALS AND METHODS

Articles published between 2/2009 and 2/2022 were searched electronically on the PubMed, EMBASE and SCOPUS databases. The initial search retrieved 780 publications and, applying the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, 33 relevant articles were identified. Twenty articles fulfilled the requirements for high (n = 1) or moderate (n = 19) methodological quality and were included. All assessments were made independently by three researchers.

RESULTS

Orthodontic forces appeared to cause a reduction in pulpal blood flow and a reduction in tooth sensibility, as indicated by increased response thresholds and increased amounts of negative responses to tooth sensibility tests. In addition, there were increases in the expression or activity levels of enzymes and neuropeptides associated with hypoxia and inflammation. Fibrotic tissue formation in the pulp was also reported.

CONCLUSIONS

Except for some histological and morphological alterations, the observed pulpal changes were in most cases only temporary, appearing within days of initiating the treatment and usually lasting for weeks. There were no clear signs of permanent damage.

Pulp blood flow changes in maxillary and mandibular anterior teeth after orthodontic retraction: a prospective study

Background

Previous studies of pulpal blood flow (PBF) changes in anterior teeth have been limited in the early phase of orthodontic treatment; less is known about the blood supply of anterior teeth in bimaxillary protrusion patients after orthodontic retraction.

Methods

Fifty bimaxillary protrusion patients (25 orthodontic patients ready for debonding and 25 non-orthodontic patients) were selected as study participants. The PBF of maxillary and mandibular anterior teeth were measured using laser Doppler flowmetry. For orthodontic patients, the PBF was measured at 1 day (T1), 1 month (T2), and 3 months (T3) after fixed appliance removal. Non-orthodontic patient PBF was measured as a control. Cone-beam computed tomography (CBCT) examinations before and after orthodontic treatment were performed for orthodontic patients to measure the root resorption. The anterior teeth in orthodontic group were further divided into subgroups according to root resorption and patient age.

Results

At T1 and T3, PBF changes did not differ significantly between the orthodontic and non-orthodontic groups. Maxillary lateral incisor, maxillary central incisor, and mandibular lateral incisor PBFs at T2 were significantly higher in the orthodontic group (P = 0.048, P = 0.04, and P = 0.021). No significant difference in PBF was found between the root resorption and non-resorption subgroups at any time point. Adolescent patients showed a higher PBF in the maxillary lateral incisor at T2 (12.23 ± 3.48) relative to that at T1 (9.10 ± 3.76) and T3 (9.81 ± 2.80) with statistically significant difference (P = 0.020).

Conclusion

For bimaxillary protrusion patients with four premolars extraction, PBF in the maxillary anterior teeth increased transiently after orthodontic appliance removal and then returned to non-orthodontic levels 3 months later. This effect was more pronounced in adolescents. The PBF of anterior teeth after orthodontic retraction may not be influenced by root resorption.

Response of human periodontal ligament to orthodontic force using superb microvascular imaging

INTRODUCTION

Remodeling of the periodontal ligament (PDL) during orthodontic tooth movement is closely related to the vascularity of the PDL, which has not been thoroughly investigated in humans. This study aimed to measure the width and vascular parameters of human PDL using superb microvascular imaging for the first time.

METHODS

Patients aged 18-25 years were selected for participation. The intervention was randomly allocated from the maxillary canines to the first molars on both sides using 50 g or 150 g of force. The width and vascular parameters of the PDL were measured using superb microvascular imaging at different time intervals (baseline, 30 minutes, and 1, 3, 7, and 14 days).

RESULTS

Before the intervention, the width of the PDL ranged from 0.14 to 0.25 mm, and the vascular index ranged from 9.40% to 13.54%. After applying orthodontic forces, the cervical and middle PDL widths increased. The vascular index decreased slightly in 30 minutes, decreased to a minimum value after 1 day, increased to the maximum in 3-7 days, and returned to baseline values in 14 days. The values of other vascular parameters showed similar trends.

CONCLUSIONS

The width and vascular parameters of the PDL changed slightly after force application, underwent changes in the period of reconstruction for 3-7 days, and eventually returned to baseline in 14 days.

The impact of mini-implant hybrid hyrax maxillary expansion on pulp blood flow and sensibility in healthy and traumatized teeth: A prospective study

INTRODUCTION

We aimed to assess pulp blood flow (PBF) and pulp sensibility changes in healthy and traumatized teeth undergoing maxillary expansion with a mini-implant hybrid hyrax appliance.

METHODS

Forty-five patients requiring maxillary expansion either with mini-implant supported hyrax expander (MARME) or tooth-borne hyrax expander (RME) had the pulp status of their maxillary anterior teeth assessed using laser Doppler flowmetry, electric pulp testing, and thermal testing (carbon dioxide snow). The study cohort was divided into 4 groups on the basis of expansion appliance (MARME or RME) and trauma experience (trauma or nontrauma). Each patient was tested before expansion, 2 weeks after expansion, and 3 months after expansion (T3). Relationships between PBF, time interval, and trauma were evaluated using linear mixed modeling.

RESULTS

Healthy teeth with RME or MARME expansion had reestablished pretreatment PBF at T3 (P >0.05). Traumatized teeth undergoing RME did not reach pretreatment PBF at T3 (P ≤0.05). There were no statistically significant changes in PBF in the MARME+Trauma group at all time intervals (P >0.05). A reduction in pulp blood flow occurred during rapid maxillary expansion from both expansion appliances; however, the relative reduction of PBF in MARME was less than with RME (P ≤0.05) 2 weeks after expansion. Most teeth across all groups (≥85%) maintained pulp sensibility at all time intervals regardless of whether there was a history of trauma.

CONCLUSIONS

Patients with transverse discrepancies and a history of trauma may benefit from MARME as evidenced by reduced changes in PBF compared with RME without affecting pulp sensibility.

Pulpal blood flow changes and pain scores related to using Superelastic 0.018-inch Nickel Titanium as the first orthodontic alignment archwire: a prospective clinical trial

Background

Optimal orthodontic force results in maximum rate of tooth movement without tissue damage. Even though starting orthodontic treatment with a thicker archwire may shorten treatment duration, the evidence on the effect of using 0.018-inch NiTi as the first alignment archwire on pulpal blood flow (PBF) status is still scarce.

Objectives

to record PBF changes and pain scores associated with using 0.018-inch NiTi as the first alignment archwire during fixed orthodontic treatment.

Methodology

Patients were selected from subjects attending postgraduate orthodontic teaching clinics at Jordan University of Science and Technology. In total, forty healthy patients who exhibited mild lower arch crowding were included. A split-mouth trial design was used. Each patient received two archwire sizes at one time joined in the midline by crimpable hook and applied in the lower arch. Patients were assigned into one of two groups based on archwire sizes used. Group 1: 0.014-inch and 0.018-inch NiTi (Six males, 14 females aged 19.4±1.33 years) and Group 2: 0.016-inch and 0.018-inch NiTi (Seven males, 13 females aged 19.6±1.45 years). The archwire size group was randomly allocated with a 1:1 allocation ratio. A Laser Doppler Flowmeter was used to measure PBF at different time intervals (T0-T5). Pain scores were recorded using a visual analogue scale (VAS). A repeated measures ANOVA and a post-hoc Bonferroni comparison tests were conducted to examine differences at the different time points before and during orthodontic alignment.

Results

For all studied archwire sizes, PBF decreased 20 minutes after their placement. Most PBF changes occurred within 24hours and continued to decrease until 72 hours after archwire placement where the maximum reduction was reached. Eventually, normal values were reverted within 1 month. PBF changes were similar between all alignment – groups.

Conclusions

Initial orthodontic alignment with 0.018-inch NiTi does not cause irreversible changes to pulpal vasculature or produces higher pain scores.

The perception of tooth whitening practices during and after orthodontic treatment: A survey of orthodontists

Background

At present, there are limited studies on how tooth whitening procedures are applied in orthodontic patients. Therefore, the objective of this study was to assess the perception of tooth whitening practices during and after orthodontic treatment.

Material and Methods

A survey of orthodontists in Medellín (Colombia) between January and October 2020 was carried out. The survey instrument was developed to obtain information regarding the perception and practices of tooth whitening during and after orthodontic treatment.

Results

133 orthodontists with a mean age of 41,6 years old participated in the survey. Over 60% of participants reported >6 years of experience as orthodontist. The majority (99,2%) reported that their patients request tooth whitening. Of these, 71,2% refer the patient to another dental professional for the procedure while 28,8% administers it. More than half of orthodontists reported that their patients request dental whitening during orthodontic treatment. The majority (>90%) of orthodontists do not recommend tooth whitening during orthodontic treatment. Furthermore, >80% consider that tooth whitening is best recommended after brackets have been removed.

Conclusions

Requests for tooth whitening from orthodontic patients is very frequent and most orthodontists favor the referral to another dental professional for the procedure. The majority do not recommend tooth whitening during orthodontic treatment and prefer waiting 1 to 3 months after brackets removal for the procedure.

Key words:Tooth whitening, orthodontic treatment, brackets.

Do orthodontic tooth movements induce pulp necrosis? A systematic review

BACKGROUND

Orthodontic tooth movements are performed by applying forces on teeth, which may cause alterations within the dental pulp. Previously published systematic reviews on the subject only included a small number of studies that assessed pulp status through reliable diagnostic methods. Since then, new evidence has been published, and a further systematic review on the subject is necessary.

OBJECTIVES

To evaluate whether there is scientific evidence to support the possibility that orthodontic tooth movements could induce pulp necrosis.

METHODS

A systematic search of articles published until June 2020 was performed using MeSH and free terms in the PubMed, Cochrane Library, LILACS, SciELO, Web of Science, EMBASE, Open Grey and Grey Literature databases. Randomized clinical trials (RCTs), nonrandomized clinical trials (nRCTs) and longitudinal (prospective or retrospective) studies that evaluated the pulp status of teeth subjected to orthodontic movements using laser Doppler flowmetry or pulse oximetry were included. The revised Cochrane risk of bias tools for randomized trials (RoB 2) and nonrandomized interventions (ROBINS-I) were used to assess the quality of the included studies. Relevant findings were summarized and evaluated. The overall quality of evidence was assessed through the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) tool.

RESULTS

Initial screening of databases resulted in 353 studies. In total, 285 studies were excluded because they were duplicates. Of 68 eligible papers, fourteen met the inclusion criteria and were selected for full-text reading. Two studies were excluded due to the methods used to evaluate pulp status. Twelve studies (five RCTs, one nRCT and six prospective) were included. Four RCTs were classified as having an unclear risk of bias and one as having a high risk of bias. The nRCT was classified as having a low risk of bias. Two prospective studies were classified as having a moderate risk of bias and four as having a serious risk of bias. The GRADE analysis demonstrated a low to very low quality of evidence.

DISCUSSION

Significant limitations regarding the randomization processes within the included RCTs and a lack of control of confounders on most nonrandomized and longitudinal studies were verified.

CONCLUSIONS

This systematic review indicates that orthodontic movements do not induce loss of pulp vitality with low to very low certainty of evidence.