Pharmacological management of pain during orthodontic treatment: a meta-analysis

The effectiveness of interventions in reducing pain related to orthodontic separation: a systematic review and meta-analysis

BACKGROUND

Pain is an unpleasant experience and annoying sensation. To control this pain during orthodontic separation, different pharmacological and non-pharmacological methods have been used.

OBJECTIVE

This systematic review and meta-analysis aimed to critically assess the evidence of the effectiveness of pharmacological and non-pharmacological methods in reducing pain induced by orthodontic separation.

SEARCH STRATEGY

An electronic search was conducted using the following databases: PubMed® (Medline), Scopus®, EMBASE®, Web of ScienceTM, Google ScholarTM, ProQuest, and Cochrane Central Register of controlled trials (CENTRAL) searching for the studies published between January 2012 and April 2023.

SELECTION CRITERIA

Only randomized controlled trials (RCTs) were included, each experimental group included patients who received elastomeric separators and one kind of pharmacological or non-pharmacological interventions for pain reduction during the separation stage.

DATA COLLECTION AND ANALYSIS

Cochrane's risk of bias tool (RoB2 tool) was applied. The Grading of Recommendations Assessment, Development, and Evaluation [GRADE] approach was used to evaluate the strength of the evidence.

RESULTS

Thirty-one studies (RCTs) were included in this systematic review. Nineteen of them were appropriate for quantitative synthesis and used VAS for pain assessment. Meta-analysis showed that low-level laser therapy (LLLT) was an effective approach for pain relief after separators placement with standard mean difference of 13.79 mm (95% confidence interval (CI): -15.64, -11.94) at 6 h and 23.34 mm at 24 h (95% CI: -25.91, -20.77). LLLT was also effective when applied in split-mouth and the standard mean difference was 8.9 mm at 6 h (95% CI: -12.86, -3.33) and 17.15 mm at 24 h (95% CI: -30.12, -4.17). Ibuprofen had a pain control effect at 6 h and at 24 h compared with the placebo group. The standard mean difference was 14.37 mm (95% CI: -20.54, -8.19) and 20.46 mm (95% CI: -27.79, -13.13), respectively. There was no difference in pain control between ibuprofen and acetaminophen. Naproxen had lower visual analog scale scores in pain perception at 6 h and the standard mean difference was 7.03 mm (95% CI: -12.67, -1.40).

CONCLUSIONS

The application of LLLT decreased the pain induced by the separation during the first day of teeth separation; the pain reduction showed an increase from 6 h to the end of the 24 h. However, the evidence is weak to moderate. The analgesics reduced the pain compared to placebo; this pain reduction had shown an increase from 6 h to the end of the 24 h. The strength of the evidence is moderate. Naproxen gel effectively reduced the pain compared to placebo; the evidence in this regard is moderate. Naproxen gel effectively reduced the pain compared to placebo, but it was less effective than the oral intake of non-steroidal anti-inflammatory drugs. However, the evidence in this regard is moderate.

REGISTRATION

This systematic review was registered with PROSPERO (CRD42022335553) during the first stages of its conduction.

Acupressure versus NSAID for relief of orthodontic pain : A randomized controlled clinical trial

AIM

To compare ibuprofen and acupressure for pain relief after insertion of elastomeric orthodontic separators.

MATERIALS AND METHODS

A randomized control clinical trial was conducted in an orthodontic clinic. A total of 75 orthodontic patients aged 12-16 years participating in the study were randomly allocated to receive either 400 mg of oral ibuprofen, applying acupressure therapy, or no pain-relief approach. Pain scores were recorded on visual analog scales (10 cm) over a week at different times (4, 10, 18, 24 h, and 1 week). The margin of equivalence was defined as 10 mm.

RESULTS

For all timepoints, the control group recorded the highest pain. For the ibuprofen and acupressure group, after 4 h, 18 h, and 1 week, no significant difference was noted. However, after 10 h, no significant difference in pain between the control and acupressure groups was noted and the ibuprofen group showed significantly lower pain. In the acupressure group, the highest pain was noted at 10 h. After this timepoint, pain progressively decreased with time and the lowest pain was noted after 1 week. In the control and ibuprofen groups, the highest pain was after 4 h, and then progressively decreased with time and the lowest pain was noted after 1 week.

CONCLUSIONS

There was no significant difference in pain perception between participants using ibuprofen or acupressure and both groups recorded significantly lower pain than the control group at most of the observed timepoints. Results support the analgesic effect of the acupressure approach.

The effect of alpha binaural beat music on orthodontic pain after initial archwire placement: A randomized controlled trial

OBJECTIVE

The objective of this article was to evaluate the effect of alpha binaural beat music on pain level after initial placement of a maxillary fixed appliance, compared to music without binaural beats (placebo) and no music (control).

METHODS

60 patients undergoing maxillary fixed orthodontic appliance and initial archwire placement were randomly allocated into the three aforementioned groups. The pain level experienced was monitored for the following seven days, using the short-form McGill pain questionnaire (SF-MPQ).

RESULTS / DESCRIPTORS

Intensity of both sensory and psychological aspects of pain reduced significantly in the binaural beat music (BBM) group, compared to the control, after the 5th day. Statistically significant lower affective and total pain scores were also found on day 6 for the placebo group, compared to the control. Present Pain Intensity (PPI): Statistically significant lower scores were found between the BBM group and the control group from days 3 to 7. Statistically significant lower scores were also found between the placebo and the control groups on days 4, 5 and 6. Visual Analog Scale (VAS): Compared to the control group, the placebo group had a lower VAS score on day 4, and the BBM group had lower scores on days 6 and 7.

CONCLUSIONS

There was a significant reduction of pain demonstrated in the BBM group, compared to the control, toward the end of the first week of treatment. There was no difference in reported pain between the BBM and placebo groups for any of the scores.

Chewing gum as a non-pharmacological alternative for orthodontic pain relief: A randomized clinical trial using an intention-to-treat analysis

Objective

To compare the effectiveness of ibuprofen, acetaminophen, and chewing gum for orthodontic pain relief and to assess if chewing gum can be a non-pharmacological alternative for orthodontic pain relief.

Methods

The study enrolled 106 patients of both sexes, aged ≥ 12 years, with body weight > 50 kg, and mild-to-moderate dental crowding in the upper arch. After randomization and allocation concealment, the intervention groups were either administered with ibuprofen (400 mg) or acetaminophen (500 mg) or chewed sugar-free chewing gum immediately after initial archwire placement and every 6 hours for 1 week if the pain persisted. The control group did not receive any pain relief. The pain was assessed on a 100-mm visual analog scale at rest and while biting down at T1 (2 hours), T2 (24 hours), T3 (2 days), T4 (3 days), T5 (7 days), and T6 (21 days). Statistical analyses were performed using the Kruskal–Wallis and post-hoc Mann–Whitney U tests (α = 0.05).

Results

The chewing gum group experienced more pain relief than the ibuprofen group at while biting down at T3 (p = 0.04) and at rest at T4 (p < 0.001). The chewing gum group reported more pain relief than the acetaminophen and control groups while biting down at T3 (p = 0.03 and p = 0.0006, respectively) and T4 (both p < 0.001).

Conclusions

Chewing gum can be a non-pharmacological alternative for orthodontic pain relief at 2 and 3 days after initial archwire placement.

Effect of verbal and written information on pain perception in patients undergoing fixed orthodontic treatment: a randomized controlled trial

BACKGROUND

Pain can discourage patients from seeking orthodontic treatment or compromise their compliance during therapy.

OBJECTIVES

To determine the effects of verbal and written information on orthodontic pain after fixed appliance placement.

TRIAL DESIGN

Two-arm parallel design randomized controlled trial.

METHODS

Healthy adolescents with permanent dentition enrolled for orthodontic treatment were assigned to the study or control group using computer-generated random lists and allocation concealment with sealed envelopes. Participants completed baseline questionnaires to assess anxiety (State-Trait Anxiety Inventory Trait Version, Form X-2) and somatosensory amplification (Somatosensory Amplification Scale). Brackets were placed in the maxillary arch, from first molar to first molar, and an Australian archwire 0.012 inch was used for alignment. General verbal information on orthodontic treatment was given to all patients by the same clinician. Participants included in the study group received also detailed verbal instructions on orthodontic pain together with a take-home information leaflet by another clinician. Outcome included assessments of pain intensity with a Numerical Rating Scale (NRS) on the day of appliance placement (Day 1, bedtime) and twice a day for the following 6 days (Day 2 to Day 7, morning, bedtime), and analgesic consumption. Participants, statistician, and clinicians who gave general verbal information on orthodontic treatment and instructions about how to score pain intensity were blinded to group assignment.

RESULTS

Sixty patients were assigned to the study (n = 30, mean age: 15.4 ± 1.3 years) or control group (n = 30, mean age: 14.7 ± 3.2 years). At baseline, no significant between-group differences were present in terms of anxiety and somatosensory amplification. Orthodontic pain scores were significantly lower in the study group compared with the control one, at bedtime on Day 1 (P < 0.05) and in the morning of Day 2 (P < 0.01). No significant between-group differences were found in following measurements. Overall, analgesic consumption was significantly lower in study compared with the control (P < 0.01).

CONCLUSION

A combination of verbal and written information on orthodontic pain after placement of fixed appliances reduced patient's self-reported pain in the early stages.

REGISTRATION

This study was not registered.

Effectiveness of different debonding techniques and adjunctive methods on pain and discomfort perception during debonding fixed orthodontic appliances: a systematic review

BACKGROUND

Pain is an unpleasant side-effect that can be experienced during orthodontic procedures including debonding of fixed appliances. Pain experience can vary depending on the appliance, debonding technique, as well as adjunctive measures used.

OBJECTIVES

The primary objective of this systematic review was to assess the effectiveness of different debonding techniques and adjunctive methods on pain/discomfort perception during debonding procedure (PDP) of fixed orthodontic appliances. The secondary objective was to assess the effects of anatomic location and gender on PDP of fixed orthodontic appliances.

SEARCH METHODS

Multiple electronic databases were searched from inception to August 2018. Reference lists of the included articles were manually screened.

SELECTION CRITERIA

Randomized clinical trials (RCTs) and controlled clinical trials were included.

DATA COLLECTION AND ANALYSIS

Study selection, data extraction, and risk of bias assessment were performed independently by two reviewers according to Cochrane guidelines, with disputes resolved by a third reviewer. Clinical heterogeneity in study design and methodology prevented quantitative synthesis of the data.

RESULTS

The search yielded 198 articles after the removal of duplicates. Seven studies were included in the final review with a total of 307 participants aged 12-60 years. Of the four studies comparing different debonding instruments of labial fixed appliances, two studies showed that the lift-off debonding instrument (LODI) produced lower PDP levels than ligature cutting pliers. Three studies compared adjunctive measures to reduce PDP of labial fixed appliances. Finger pressure and bite wafers significantly reduced PDP levels. Analgesics administration (ibuprofen + paracetamol tablets) 1 hour prior to debonding also reduced PDP. PDP was significantly higher in anterior segments and in females.

LIMITATIONS

The authors acknowledge that there was clinical heterogeneity among the included studies and that the potential effect of diurnal variation on pain during debonding was not considered in any of the included trials.

CONCLUSIONS AND IMPLICATIONS

There is weak evidence indicating that using the LODI may reduce PDP of labial fixed appliances. Adjunctive measures such as an intrusive force with finger pressure, bite wafers, and preoperative analgesia may further aid PDP control. Further well-designed parallel-group RCTs taking into consideration the diurnal variation in pain are required.

REGISTRATION

PROSPERO (CRD42017084474).

FUNDING

None.

CONFLICT OF INTEREST

The authors declare that there is no conflict of interest.

Systematic reviews in orthodontics: Impact of the PRISMA for Abstracts checklist on completeness of reporting

INTRODUCTION

This study evaluated and compared the completeness of reporting of abstracts of orthodontics systematic reviews before and after the publication of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) extension for Abstracts Checklist (PRISMA-A).

METHODS

Abstracts of systematic reviews and meta-analyses in orthodontics published in PubMed, Latin American and Caribbean Health Sciences Literature, and the Cochrane Database of Systematic Reviews databases before March 23, 2018, that met the predefined inclusion and exclusion criteria, were evaluated using the 12 items of PRISMA-A, scoring each item from 0 to 2. Abstracts were classified into 2 groups: before and after publication of the PRISMA-A checklist. Three calibrated evaluators (intraclass correlation coefficient and kappa > 0.8) assessed the scores for compliance with the checklist. The number of authors, country of affiliation of the first author, performance of meta-analysis, and topic of the article were recorded. A regression analysis was performed to assess the associations between abstract characteristics and the PRISMA-A scores.

RESULTS

Of 1034 abstracts evaluated, 389 were included in the analysis. The mean PRISMA-A score was 53.39 (95% CI, 51.83-54.96). The overall score for studies published after the publication of the checklist was significantly higher than for studies published before (P ≤ 0.0001). The components returning significantly higher scores after publication of PRISMA-A were title (P = 0.024), information from databases (P = 0.026), risk of bias (P ≤ 0.0001), included studies (P ≤ 0.0001), synthesis of results (P ≤ 0.0001), interpretation of results (P = 0.035), financing and conflict of interest (P ≤ 0.0001), and registration (P ≤ 0.0001). These results showed the positive effect of PRISMA-A had on the quality of reporting of orthodontics systematic reviews. Nevertheless, the poor adherence revealed that there is still need for improvement in the quality of abstract reporting.

CONCLUSIONS

The quality of reporting of abstracts of orthodontic systematic reviews and meta-analyses increased after the introduction of PRISMA-A.

Comparing the effectiveness profile of pharmacological interventions used for orthodontic pain relief: an arm-based multilevel network meta-analysis of longitudinal data

Background and objectives

We compare the effectiveness profile of various analgesics used for orthodontic pain relief over a 1-week time period by conducting a longitudinal network meta-analysis (NMA).

Search methods

The MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials databases were searched till 31st December 2015 to identify the relevant studies. Additional studies were identified by hand searching journals and reference lists. Unpublished literature was also searched.

Selection criteria

Eligible studies were randomized-controlled trials (RCTs) evaluating the effectiveness of pharmacological interventions for pain relief after placement of separator or initial aligning arch wire.

Data collection and analysis

Pain intensity data at 2, 6, 12, 24, 36, 48, 72, 96, and 168 hours was collected. In addition, data were also extracted for potential covariates (age, sex, and procedure). A covariate-adjusted arm-based multilevel random coefficient model was used for evidence synthesis.

Results

Fifteen RCTs (1341 participants; male/females 595, 44.6%/746 55.4%; mean age 17.3 years, SD 4.1) were included. A total of 11 nodes (Acetaminophen, Aspirin, Etoricoxib, Flurbiprofen, Ibuprofen, Lumiracoxib, Meloxicam, Naproxen, Piroxicam, Placebo, and Control) were identified out of which five nodes (Placebo, Ibuprofen, Naproxen, Acetaminophen, and Aspirin) had subnodes (based on timing of administration). Compared to Control, Placebo, Flurbiprofen, Lumiracoxib, and Meloxicam were not significantly effective. Etoricoxib (most effective) and Piroxicam (second most effective) were effective over a long period which lasted up to 96 and 72 hours, respectively. Ibuprofen, Acetaminophen, Naproxen, and Aspirin were effective at 6, 12, and 24 hours. The effectiveness of these analgesics was significantly influenced by the timing of administration. Assessment of heterogeneity, transitivity, inconsistency, and publication bias revealed no major threat to the NMA derived estimates.

Conclusion

Compared to the Control, Placebo was least effective whereas Etoricoxib was the most effective analgesic in reducing orthodontic pain. Administration timing has significant influence on the effectiveness profile of analgesics routinely used for managing orthodontic pain.

Comparison of two analgesics used for pain relief after placement of orthodontic separators

Objective

The purpose of this study was to assess the possible effect of two analgesics: paracetamol (500 mg) and ibuprofen (400 mg) on pain and routine life of the patients after placement of orthodontic separators.

Methodology

Ninety patients aged 11–41 years undergoing fixed comprehensive orthodontic treatment requiring placement of different orthodontic separators participated in the study. Following placement of separators, the participants were randomly assigned to 1 of 3 groups: paracetamol (500 mg) given every 6 h for 3 days, ibuprofen (400 mg) given every 8 h for 2 days and control group in which no analgesic was given. A questionnaire comprising of 7 questions was distributed to the participants and were asked to report their feeling of pain. The collected data were tabulated and the statistical analysis was performed using ANOVA, chi-square test, and t-test with a significance level of p < 0.05.

Results

In general, the level of pain was high for all groups in the first three days. Then it was gradually reduced until the 7th day of the study. Few patients reported feeling of pain during their sleep whereas a significant reduction of the pain was reported during eating and chewing after the 3rd day of separators. However, some participants felt continuous pain on the 1st and 2nd days and it was reduced gradually on the 3rd day until the 7th day following application of separators.

Conclusion

The patients prescribed ibuprofen did not report any problem with tooth movement along with significant reduction in pain as compared to paracetamol. Pain relief medication after placement of separators should be taken only if patient feels intolerable pain but not as routine practice.

Pharmacological interventions for pain relief during orthodontic treatment

BACKGROUND

Pain is a common side effect of orthodontic treatment. It increases in proportion to the amount of force applied to the teeth, and the type of orthodontic appliance used can affect the intensity of the pain. Pain during orthodontic treatment has been shown to be the most common reason for people wanting to discontinue treatment, and has been ranked as the worst aspect of treatment. Although pharmacological methods of pain relief have been investigated, there remains some uncertainty among orthodontists about which painkillers are most suitable and whether pre-emptive analgesia is beneficial. We conducted this Cochrane Review to assess and summarize the international evidence relating to the effectiveness of analgesics for preventing this unwanted side effect associated with orthodontic treatment.

OBJECTIVES

The objectives of this review are to determine:- the effectiveness of drug interventions for pain relief during orthodontic treatment; and- whether there is a difference in the analgesic effect provided by different types, forms and doses of analgesia taken during orthodontic treatment.

SEARCH METHODS

Cochrane Oral Health's Information Specialist searched the following databases: the Cochrane Oral Health Trials Register (to 19 June 2017), the Cochrane Central Register of Controlled Trials (CENTRAL;the Cochrane Library 2016, Issue 7), MEDLINE Ovid (1946 to 19 June 2017), Embase Ovid (1980 to 19 June 2017) and CINAHL EBSCO (Cumulative Index to Nursing and Allied Health Literature; 1937 to 19 June 2017). The US National Institutes of Health Ongoing Trials Register (ClinicalTrials.gov) and the World Health Organization International Clinical Trials Registry Platform were searched on the 19 June 2017 for ongoing studies. We placed no restrictions on language or date of publication when searching the electronic databases.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) relating to pain control during orthodontic treatment. Pain could be measured on a visual analogue scale (VAS), numerical rating scale (NRS) or categorical scale.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the search results, agreed the studies to be included and extracted information from the included studies regarding methods, participants, interventions, outcomes, harms and results. We planned to resolve any discrepancies or disagreements through discussion. We used the Cochrane 'Risk of bias' tool to assess the risk of bias in the studies.

MAIN RESULTS

We identified 32 relevant RCTs, which included 3110 participants aged 9 to 34 years, 2348 of whom we were able to include in our analyses. Seventeen of the studies had more than two arms. We were able to use data from 12 trials in meta-analyses that compared analgesics versus control (no treatment or a placebo); nine that compared non-steroidal anti-inflammatories (NSAIDs) versus paracetamol; and two that compared pre-emptive versus post-treatment ibuprofen for pain control following orthodontic treatment. One study provided data for the comparison of NSAIDs versus local anaesthetic.We found moderate-quality evidence that analgesics effectively reduced pain following orthodontic treatment when compared to no treatment or a placebo at 2 hours (mean difference (MD) -11.66 mm on a 0 to 100 mm VAS, 95% confidence interval (CI) -16.15 to -7.17; 10 studies, 685 participants), 6 hours (MD -24.27 mm on a VAS, 95% CI -31.44 to -17.11; 9 studies, 535 participants) and 24 hours (MD -21.19 mm on a VAS, 95% CI -28.31 to -14.06; 12 studies, 1012 participants).We did not find any evidence of a difference in efficacy between NSAID and paracetamol at 2, 6 or 24 hours (at 24 hours: MD -0.51, 95% CI -8.93 to 7.92; 9 studies, 734 participants; low-quality evidence).Very low-quality evidence suggested pre-emptive ibuprofen gave better pain relief at 2 hours than ibuprofen taken post treatment (MD -11.30, 95% CI -16.27 to -6.33; one study, 41 participants), however, the difference was no longer significant at 6 or 24 hours.A single study of 48 participants compared topical NSAIDs versus local anaesthetic and showed no evidence of a difference in the effectiveness of the interventions (very low-quality evidence).Use of rescue analgesia was poorly reported. The very low-quality evidence did not show evidence of a difference between participants taking ibuprofen and participants taking paracetamol (relative risk (RR) 1.5, 95% CI 0.6 to 3.6). Nor did we find evidence of a difference between groups in likelihood of requiring rescue analgesia when ibuprofen was taken pre-emptively compared to after treatment (RR 0.8, 95% CI 0.3 to 1.9).Adverse effects were identified in one study, with one participant developing a rash that required treatment with antihistamines. This was provisionally diagnosed as a hypersensitivity to paracetamol.

AUTHORS' CONCLUSIONS

Analgesics are more effective at reducing pain following orthodontic treatment than placebo or no treatment. Low-quality evidence did not show a difference in effectiveness between systemic NSAIDs compared with paracetamol, or topical NSAIDs compared with local anaesthetic. More high-quality research is needed to investigate these comparisons, and to evaluate pre-emptive versus post-treatment administration of analgesics.

Methodologies in Orthodontic Pain Management: A Review

Introduction:

Patients experience pain and discomfort during active orthodontic treatment with fixed appliances. Pain is considered a subjective response to noxious stimuli. It can vary from person to person and is influenced by certain factors such as age, gender, previous pain experiences, stress or anxiety, and type of appliance.

Objective:

The objective of this literature review was to discuss conventional versus recently introduced treatment modalities used in pain management for orthodontic patients.

Discussion:

According to the reviewed articles, both pharmacological and non-pharmacological methods were introduced in orthodontic pain management. However, orthodontists must use their best professional judgment to assess each case individually and select an appropriate treatment modality based on pain threshold level of an individual.

Conclusion:

Nevertheless, further investigations are required in this field.

CO2 low-level laser therapy has an early but not delayed pain effect during experimental tooth movement

OBJECTIVES

To test the hypothesis that the use of low-level laser therapy (LLLT) reduces elevated pain by controlling the release of neurochemicals during orthodontic tooth movement.

SETTING AND SAMPLE POPULATION

Department of Orthodontics and Dentofacial Orthopedics, Okayama University. Sixty-five Sprague Dawley rats were subjected to tooth movement and LLLT.

MATERIALS AND METHODS

Adult Sprague Dawley rats were used in this study. Groups included day 0 controls, irradiation only controls and with or without irradiation sacrificed at 1, 3, 5, 7 and 14 days after tooth movement (n=5 each, total n=65). Tooth movement was achieved by insertion of an elastic module between molar teeth. Immunohistochemistry for CD-11b, GFAP and c-fos in the brain stem was performed. Stains were quantified by constructing a three-dimensional image using IMARIS, and counted using NEURON TRACER and WinROOF software. Two-way ANOVA followed by a Tukey's post hoc test (P<.05) was used for statistical comparison between groups.

RESULTS

C-fos expression was significantly increased at one and three days after tooth movement. LLLT significantly diminished this increase in c-fos expression only at one day after tooth movement CD-b11 and GFAP expression also significantly increased after tooth movement. No significant change was observed for CD-11b and GFAP expression in the central nervous system upon LLLT.

CONCLUSION

Low-level laser therapy may reduce early neurochemical markers but have no effect on delayed pain neurochemical markers after tooth movement.

Effect of 5% benzocaine gel on relieving pain caused by fixed orthodontic appliance activation. A double-blind randomized controlled trial

AIM

To compare the effectiveness of 5% benzocaine gel and placebo gel on reducing pain caused by fixed orthodontic appliance activation.

SETTING AND SAMPLE POPULATION

Thirty subjects (15-25 years) undergoing fixed orthodontics.

METHODS AND MATERIALS

A randomized, double-blind, placebo-controlled and cross-over clinical trial study was conducted. Subjects were asked to apply a placebo gel and 5% benzocaine gel, exchangeable in two consecutive appointments, twice a day for 3 days and mark their level of pain on a VAS scale. The pain severity was evaluated by means of Mann-Whitney U-test for comparing two gel groups, Kruskal-Wallis nonparametric test for overall differences and post hoc test of Dunnett for paired multiple comparisons. p-value was assigned <0.05.

RESULTS

The overall mean value of pain intensity for benzocaine and placebo gels was 0.89 and 1.15, respectively. The Mann-Whitney U-test indicated that there was no significant difference between overall pain in both groups (mean difference = 0.258 p ˂ 0.21). For both groups, pain intensity was significantly lower at 2, 6 and 24 h compared with pain experienced at days 2, 3 and 7.

CONCLUSION

Benzocaine gel caused a decrease in pain perception at 2 h compared with placebo gel. Peak pain intensity was at 2 h for placebo gel and at 6 h for benzocaine gel, followed by a decline in pain perception from that point to day 7 for both gels.

Current advances in orthodontic pain

Orthodontic pain is an inflammatory pain that is initiated by orthodontic force-induced vascular occlusion followed by a cascade of inflammatory responses, including vascular changes, the recruitment of inflammatory and immune cells, and the release of neurogenic and pro-inflammatory mediators. Ultimately, endogenous analgesic mechanisms check the inflammatory response and the sensation of pain subsides. The orthodontic pain signal, once received by periodontal sensory endings, reaches the sensory cortex for pain perception through three-order neurons: the trigeminal neuron at the trigeminal ganglia, the trigeminal nucleus caudalis at the medulla oblongata and the ventroposterior nucleus at the thalamus. Many brain areas participate in the emotion, cognition and memory of orthodontic pain, including the insular cortex, amygdala, hippocampus, locus coeruleus and hypothalamus. A built-in analgesic neural pathway—periaqueductal grey and dorsal raphe—has an important role in alleviating orthodontic pain. Currently, several treatment modalities have been applied for the relief of orthodontic pain, including pharmacological, mechanical and behavioural approaches and low-level laser therapy. The effectiveness of nonsteroidal anti-inflammatory drugs for pain relief has been validated, but its effects on tooth movement are controversial. However, more studies are needed to verify the effectiveness of other modalities. Furthermore, gene therapy is a novel, viable and promising modality for alleviating orthodontic pain in the future.

Periodontal CGRP contributes to orofacial pain following experimental tooth movement in rats

Calcitonin-related gene peptide (CGRP) plays an important role in orofacial inflammatory pain. The aim of this study was to determine whether periodontal CGRP contributes to orofacial pain induced by experimental tooth movement in rats. Male Sprague-Dawley rats were used in this study. Closed coil springs were used to deliver forces. Rats were euthanized on 0d, 1d, 3d, 5d, 7d, and 14d following experimental tooth movement. Then, alveolar bones were obtained for immunostaining of periodontal tissues against CGRP. Two hours prior to euthanasia on each day, orofacial pain levels were assessed through rat grimace scale. CGRP and olcegepant (CGRP receptor antagonist) were injected into periodontal tissues to verify the roles of periodontal CGRP in orofacial pain induced by experimental tooth movement. Periodontal CGRP expression levels and orofacial pain levels were elevated on 1d, 3d, 5d, and 7d following experimental tooth movement. The two indices were significantly correlated with each other and fitted into a dose-response model. Periodontal administration of CGRP could elevate periodontal CGRP expressions and exacerbate orofacial pain. Moreover, olcegepant administration could decrease periodontal CGRP expressions and alleviate orofacial pain. Therefore, periodontal CGRP plays an important role in pain transmission and modulation following experimental tooth movement. We suggest that it may participate in a positive feedback aiming to amplify orofacial pain signals.

Low-level laser therapy for orthodontic pain: a systematic review

This review aimed to evaluate the clinical outcome of different lasers management on orthodontic pain. Cochrane Library (Issue 7, 2014) and MEDLINE (1966-2014.7) were searched to collect randomized controlled trials on lasers for orthodontic pain. Studies meeting the inclusion criteria were systematically evaluated. The Cochrane Collaboration tools RevMan5.1.7 and GRADEpro 3.6 were used in this systematic review and meta-analysis. As a result, 11 randomized controlled trials (RCTs) studying on low-level laser therapy (LLLT) for orthodontic pain control were included. Meta-analysis and risk of bias assessment were implemented using RevMan5.1.7, and level of evidence assessments was measured by GRADEpro 3.6. In the outcome of the score of the most painful day, the comparison of laser versus placebo (pain associated with tooth movement) demonstrated that LLLT reduced the pain score significantly compared with placebo groups (MD = -4.39, 95% CI range -5.9--2.88, P < 0.00001). In the same way, the most painful day was significantly brought forward in laser versus control group (MD = -0.42, 95% CI range -0.74--0.10, P = 0.009). Furthermore, the outcome of the end of pain day showed a trend of pain termination earlier in laser versus control and placebo groups, but without statistical significance (MD = -1.37, 95% CI range -3.37-0.64, P = 0.18 and MD = -1.04, 95% CI range -4.22-2.15, P = 0.52). However, for the reason of downgrade factors, all the GRADE level of evidences of eight comparisons for three outcomes showed a very low quality. Therefore, for the methodological shortcomings and risk of bias of RCTs included, insufficient evidence was submitted to judge whether LLLT was effective in relieving orthodontic pain. Further and more perfect researches should be done in order to recommend LLLT as a routine method for orthodontic pain.

The effect of diode superpulsed low-level laser therapy on experimental orthodontic pain caused by elastomeric separators: a randomized controlled clinical trial

The aim of this study was to evaluate the efficacy of diode superpulsed low-level laser therapy (SLLLT) in reducing experimentally induced orthodontic pain. Overall, 120 subjects (23.01 ± 1.39 years) were enrolled for a clinical trial. Subjects were randomly assigned to upper (U, N = 60) or lower (L, N = 60) jaw groups. All subjects received 4 elastomeric separators mesial and distal to the upper (U group) or lower (L group) right first molar and bicuspids. Each subject of the U and L groups was randomly assigned to laser (Ul, N = 20 and Ll, N = 20), placebo (Up, N = 20 and Lp, N = 20) or control (Uc, N = 20 and Lc, N = 20) sub-groups. Subjects in laser groups received a single GaAs diode SLLLT application (910 nm, 160 mW, beam diameter of 8 mm, applied for 340 s) immediately after placing orthodontic separators. Placebo groups received a simulated SLLLT and controls did not receive any therapy. All participants compiled a survey on pain duration and a 100-mm visual analogue scale immediately after the separators placement and after 12, 24, 36, 48, 72, and 96 h. Pain intensity of laser groups was significantly lower compared to placebo and control groups (p = 0.0001). In the laser group, 70% of subjects felt pain, while in the placebo and control groups all subjects felt pain (p = 0.0001). The end of pain occurred earlier in laser compared to placebo and control groups (p = 0.021). A single-diode SLLLT application appeared to be effective in reducing the intensity and duration of experimentally induced orthodontic pain and could be used in daily orthodontic practice.