Pain experience in adults undergoing treatment: A longitudinal evaluation

Orthodontic pain is related to oral health-related quality of life in orthodontic patients

INTRODUCTION

Orthodontic pain (OP) is a subjective experience induced by prolonged force on the teeth in fixed orthodontic treatment. OP acts as a predictor of aspects related to oral health-related quality of life (OHRQOL). It is important to understand the extent of the impact of OP on a patient's daily life, especially on stomatognathic function and social impact.

OBJECTIVE

To assess the correlation between OP and OHRQOL in fixed orthodontic treatment patients.

MATERIAL AND METHODS

The comparative pain rating scale is used to assess pain intensity, while the oral health impact profile-14 (OHIP-14) assesses the impact of OP severity on OHRQOL of 57 patients undergoing fixed orthodontic treatment in the early stages of treatment (1-3 months of treatment) at the Dental Hospital, Universitas Airlangga. Gender, age, and malocclusion classifications were also analyzed for their influence. The data were analyzed using Spearman correlation and two-way analysis of variance (ANOVA).

RESULTS

In the initial phase of treatment, most of the patients (53%) experienced mild OP and moderate OP (39%), and OP was reduced over a week. The overall OHRQOL score was 17.4 ± 8, which indicates a negative impact on OHRQOL. There were also positive correlation dimensions of OHRQOL, which include the dimensions of physical limitations, psychological discomfort, and psychological limitations (r > 0.50). There was a significant difference between age groups in OP perception and OHRQOL (P < 0.05).

CONCLUSIONS

There was a positive correlation between OP intensity and OHRQOL experienced by fixed orthodontic patients at the Dental Hospital, Universitas Airlangga.

Biological and psychological factors affecting the sensory and jaw motor responses to orthodontic tooth movement

Orthodontic tooth movement (OTM) is associated with an inflammatory response, tooth pain (i.e. orthodontic pain) and changes in dental occlusion. Clinical realms and research evidence suggest that the sensory and jaw motor responses to OTM vary significantly among individuals. While some adjust well to orthodontic procedures, others may not and can experience significant pain or not adjust to occlusal changes. This is of concern, as clinicians cannot anticipate an individual's sensorimotor response to OTM. Converging evidence shows that some psychological states and traits significantly affect the sensorimotor response to OTM and may considerably affect an individual's adaptation to orthodontic or other dental procedures. We performed a topical review to synthesize the available knowledge about the behavioural mechanisms regulating the sensorimotor response to OTM, with the intent of informing orthodontic practitioners and researchers about specific psychological states and traits that should be considered while planning orthodontic treatment. We report on studies focusing on the role of anxiety, pain catastrophising, and somatosensory amplification (i.e. bodily hypervigilance), on sensory and jaw motor responses. Psychological states and traits can significantly affect sensory and jaw motor responses and a patient's adaptation to orthodontic procedures, although large interindividual variability exists. Clinicians can use validated instruments (checklists or questionnaires) to collect information about patients' psychological traits, which can assist in identifying those individuals who may not adjust well to orthodontic procedures. The information included in this manuscript also assists researchers investigating the effect of orthodontic procedures and or/appliances on orthodontic pain.

Comparison of pain intensity and impacts on oral health-related quality of life between orthodontic patients treated with clear aligners and fixed appliances: a systematic review and meta-analysis

OBJECTIVE

This study aimed to compare the pain intensity and impacts on oral health-related quality of life (OHRQoL) between orthodontic patients treated with clear aligners (CAs) and fixed appliances (FAs).

METHODS

A systematic search was conducted up to December 2022 using PubMed, Web of Science, Cochrane Central Register of Controlled Trials, and Embase. Randomized controlled trials (RCTs) and prospective non-randomized controlled trials (non-RCTs) comparing pain intensity or OHRQoL between patients treated with CAs and FAs were included. The risk of bias (RoB) of individual studies was evaluated using the Cochrane RoB tool 2.0 and ROBINS-I tool for RCTs and non-RCTs, respectively. Further, meta-analyses were separately conducted for each included study using the total oral health impact profile (OHIP)-14 and visual analog scale (VAS) scores to evaluate OHRQoL and pain intensity, respectively.

RESULTS

Overall, 12 studies (5 RCTs and 7 non-RCTs) were included in the study. Subgroup analyses conducted according to the total OHIP-14 scores revealed that patients treated with CAs had higher OHRQoL at 1 week, 1 month, and 6 months of the treatment. Meanwhile, subgroup analyses conducted according to the VAS scores revealed that pain levels were lower in the CA group only at 3 and 4 days of the treatment.

CONCLUSIONS

Patients treated with clear aligners had higher OHRQoL than those treated with fixed appliances during orthodontic treatment. However, OHRQoL appeared to be similar between the two groups at the end of the treatment. Moreover, patients treated with clear aligners experienced lesser pain than those treated with fixed appliances on the third and fourth day after the initial treatment. The difference in pain intensity between the two treatment modalities was not noted at other time points.

Implant-supported canine retraction using different reactivation intervals of elastomeric chains: A CBCT-based split-mouth randomized controlled trial

INTRODUCTION

Orthodontists attempt to maximize treatment efficiency regarding time, tooth position and adverse effects. A new approach, not yet explored, is the activation frequency.

OBJECTIVE

The aim of this split-mouth randomized controlled trial was to evaluate the effect of reactivation intervals on the efficiency of tooth movement.

METHODS

Thirty eight patients having a Class I malocclusion with bimaxillary dentoalveolar protrusion or severe crowding, Class II with mandibular deficiency or Class III, requiring first premolar extraction and canine retraction were recruited. Elastomeric chains producing 150g were replaced every two, four, six or eight weeks. There were 36, 37, 36, and 36 quadrants randomly allocated to these groups, respectively. The canine retraction rate was the primary outcome. Canine tipping, rotation, and root resorption and pain were the secondary outcomes. Only the outcome assessors were blinded to group assignment.

RESULTS

The average total movement for the 6 months was 5.14, 5.31, 2.79 and 3.85 mm for the two-week, four-week, six-week and eight-week reactivation intervals, respectively. Root resorption was significantly higher in the two-week and four-week groups. No adverse events were observed.

CONCLUSION

The canine retraction rate, tipping, rotation and pain were similar in 2, 4, 6 and 8-week activation intervals groups. Longer reactivation intervals show less root resorption. The trial protocol was not pre-registered. The study was self-funded.

Influence of functional and esthetic expectations on orthodontic pain

OBJECTIVES

To investigate the effect of orthodontic treatment outcome (OTO) expectations on the level of pain intensity experienced after orthodontic elastomeric separation (OES).

MATERIALS AND METHODS

A total of 100 orthodontic patients (74 female and 26 male, age 14 years and above) from the Faculty of Dentistry, Mahidol University were enrolled. Before OES, questionnaires were administered to obtain patients' expectations regarding various aspects of OTO as well as OES pain expectations. Real-time self-reported pain intensity from OES at the maxillary and mandibular first permanent molars was obtained before and immediately after separator placement and at 6 h, 24 h, and then every day until day 7 after OES. Data were analyzed for the relationship between OTO expectations and OES pain intensity. The level of significance was set at 0.05.

RESULTS

The maximum OES pain intensity occurred on day 2 after OES and gradually decreased to the pretreatment level on day 7. The degree of facial, tooth alignment, masticatory function improvement expectations, and a high level of OES pain expectations were significantly associated with the severity of OES pain after separator placement.

CONCLUSION

Esthetic and functional expectations of OTO were significantly associated with OES pain intensity. Thus, knowledge about esthetic and functional expectations may help to predict patient's pain response to orthodontic treatment.

Impact of the use of dental services on dental pain according to adolescents' skin colour: a 10-year cohort

OBJECTIVE

Evaluate the association of the interaction between the use of dental services and the skin colour on the occurrence of dental pain over time.

MATERIAL AND METHODS

This study is a cohort with 10 years of follow-up, started in 2010 with a sample of 639 preschool children (1-5 years old). The use of dental services, race and the presence of dental pain were self-reported by the individuals according to predefined criteria. Multilevel logistic regression analysis was performed to assess the interaction between skin colour and use of dental services in the occurrence of dental pain over time.

RESULTS

About 449 and 429 were reassessed in 2017 and 2020, respectively. The occurrence of dental pain across the cohort was 60.7%. Caucasian individuals who used dental services throughout the cohort had a 51% lower chance of having a dental pain than those who used dental services but were non-white (OR 0.49; 95% IC 0.27-0.90).

CONCLUSION

There was a racial inequity in the occurrence of dental pain among individuals who managed to make use of dental services throughout the follow-ups.

CLINICAL RELEVANCE

The differences found should serve as a warning to the way how individuals with different characteristics are treated and must be used to combat this inequity. Individuals should receive resolute and personalized treatments according to their clinical condition and not according to their socioeconomic characteristics.

Altered Brain Topological Property Associated With Anxiety in Experimental Orthodontic Pain

Background

Orthodontic pain is orofacial pain caused by tooth movement. Anxiety is a strong predictor of the severity of such pain, but little is known about the underlying neuropsychological mechanisms of such effects. The purpose of this study was to investigate the effect of orthodontic pain on brain functional networks and to define the mediating role of anxiety in orthodontic pain and brain function.

Methods

Graph theory-based network analyses were applied to brain functional magnetic resonance imaging data from 48 healthy participants exposed to 24 h orthodontic pain stimuli and 49 healthy controls without any stimulation.

Results

In the experimental orthodontic pain stimulation, brain functional networks retained a small-world organization. At the regional level, the nodal centrality of ipsilateral brain nodes to the pain stimulus was enhanced; in contrast the nodal centrality of contralateral brain areas was decreased, especially the right mid-cingulate cortex, which is involved in pain intensity coding. Furthermore, anxiety mediated the relationship between nodal efficiency of mid-cingulate cortex and pain severity.

Conclusion

The results illuminate the neural mechanisms of orthodontic pain by revealing unbalanced hemispherical brain function related to the unilateral pain stimulation, and reveal clinically exploitable evidence that anxiety mediates the relationship between nodal function of right mid-cingulate cortex and orthodontic pain.

Is catastrophizing associated with pain perception in early phase of orthodontic treatment? a cohort study

BACKGROUND AND OBJECTIVES

This study aimed to investigate the association between pain perception and catastrophizing at the beginning of orthodontic treatment; and the association between pain during orthodontic treatment and demographic, clinical, and other psychological factors.

METHODS

A cohort study with 44 patients (28.9±15.05 years old; 25 females and 19 males) under orthodontic treatment with fixed appliances had their pain perception evaluated through a visual analog scale at baseline (before activation), 6 h, 24 h, 2^nd day, 3^rd day, 5^th day, and 7^th day after activation. The scores at each evaluation period after the first (T1), second (T2), and third (T3) appointments were compared by analysis of variance. A multivariate Poisson regression analysis verified the association between pain perception and Pain Catastrophizing Scale (PCS); and demographic (age, gender), clinical (tooth crowding, tooth loss, analgesic intake, and archwire characteristics), and other psychological (dental anxiety, and previous negative dental experiences) independent variables (p<.05).

RESULTS

Catastrophizing (RR=1.03, 95%CI 1.01 to 1.05, p=.0001) showed a weak risk of pain perception at T1. The peak of pain occurred 24 h after activation at T1, T2, and T3. Significant higher scores were observed at T1 in comparison to T2 (F_T1,T2 =11.82, p=.005) and T3 (F_T1,T3 =5.09, p=.03). Wire diameter, tooth crowding, and single arch treatment were found as risk factors for pain. Patients without tooth loss had half of the risk of pain perception, while analgesics intake and older patients were also found with a weak protective association. Dental anxiety and negative dental experience were not associated with pain perception.

CONCLUSION

Catastrophizing has a mild influence on pain perception and only after the first orthodontic activation. Patients with tooth losses, tooth crowding, and using thicker archwires are more likely to report pain after orthodontic activations.

The effect of piezocision vs no piezocision on maxillary extraction space closure: A split-mouth, randomized controlled clinical trial

INTRODUCTION

The aim of this 2-arm-parallel, split-mouth trial was to investigate the effects of piezocision compared with no piezocision on maxillary canine distalization and to evaluate patient perceptions on the surgical procedure.

METHODS

Twenty-two participants requiring extractions of maxillary first premolars were recruited from the Department of Orthodontics (Sydney Dental Hospital) waiting list. After leveling and alignment, a minimum of 3 mm space was required for canine retraction. Piezocision cuts distal to the canines were 4 mm long and 3 mm deep into the buccal cortical plate. The canine retraction was initiated on both sides immediately after surgery, with coil springs delivering 150 g of force per side. Random assignment of piezocision or control intervention on the patient's right side was performed (www.randomisation.com) for the random number generation, and allocation concealment was accomplished with opaque, sealed envelopes. Patients were assessed every 6 weeks for coil activation and alginate impressions over 18 weeks. The primary outcome was the amount of tooth movement in mm. Secondary outcomes were canine rotation, anchorage loss measured on scanned dental models, and patient pain levels and perception on piezocision using visual analog scale questionnaires. Blinding was feasible for the dental model measurements.

RESULTS

Twenty patients completed the trial. The treatment × time interaction showed no statistically or clinically significant differences in maxillary extraction space closure (b = -0.02; 95% confidence interval [CI], -0.29 to 0.25; P = 0.89) canine rotation (b = -1.45; 95% CI, -4 to 1.09; P = 0.26) and anchorage loss (b = -0.02; 95% CI, -0.38 to 0.34; P = 0.92). All patients except for one had minimal pain associated with the piezocision surgery but found the procedure tolerable and would recommend it. No harm occurred during the trial.

CONCLUSIONS

Piezocision-assisted maxillary canine distalization was similar to distalization with conventional orthodontics with patients tolerating the procedure.

Comparative Analysis of Periodontal Pain According to the Type of Precision Orthodontic Appliances: Vestibular, Lingual and Aligners. A Prospective Clinical Study

The objective of this prospective clinical study was to analyze the pain (intensity, location and type) that patients presented after the placement of different types of orthodontic appliances: conventional, low friction, lingual and aligners. The sample consisted of 120 patients divided into four groups: conventional (CON), low friction (LF), lingual (LO) and aligners (INV). The participants were given the Short-Form McGill Pain Questionnaire (Ortho-SF-MPQ), where they had to record the pain intensity (no pain, mild, moderate or intense) and the periodontal location at different time points, from the first 4 h to 7 days after the start of treatment. In all the study groups, the most frequent location was both anterior arches, with maximum values between 56.7% (CON group at 24 h) and 30% (LO group at 4 h). The "whole mouth" and "complete lower arch" locations were indicated only by the patients in the lingual group. Regarding pain intensity, the patients reported a higher percentage of mild-moderate pain during the first 3 days of treatment (96.7% in LO at 4 h, 86.7% in CON, 83.3% in LF and 90% in INV at 24 h); later, the reported pain decreased to no pain/mild pain, especially in the lingual group, until reaching values close to zero at 7 days post-treatment. The most frequent type of pain was acute in the low friction and lingual groups (with maxima of 60% and 46.7% at 24 h, respectively). On the contrary, in the conventional (36.7% at 4 h) and Invisalign (40% at 24 h) groups, the sensitive type was the most frequent. There are differences regarding periodontal pain in its intensity, location and type according to the use of different orthodontic techniques.

The Influence of Friction on Design of the Type of Bracket and Its Relation to OHRQoL in Patients Who Use Multi-Bracket Appliances: A Randomized Clinical Trial

Background and objectives: The aim of this study was to evaluate the influence of friction on design of the type of bracket, patients’ perception of pain and the impact on their oral health-related quality of life. Materials and Methods: A randomized clinical trial was carried out with 90 patients (62.2% women and 37.8% men) with three kinds of fixed multi-bracket appliances: Conventional (GC), fixed multi-bracket low friction (GS) and self-ligating (GA). The VAS (Visual Analogue Scale) was used to determine pain during the first seven days of treatment at different points in time. The patients were also given the OHIP-14 (Oral Health Impact Profile) questionnaire to analyse their oral health-related quality of life (OHRQoL) after the first 30 days of treatment. The ANOVA test was used for the analysis of the variables and the post hoc Bonferroni test for the comparison between groups. Results: Maximum pain was observed between one and two days after the start of treatment. The GC group showed the greatest degree of pain, with maximum values (4.5 ± 2.0) at 24 h. The self-ligation brackets show lower impact on patients’ oral health-related quality of life (0.8 ± 2.2, p < 0.01). Conclusions: Friction in the type of bracket influences pain and the Oral Health-Related Quality of Life of patients who use multi-bracket fixed orthodontics.

Patients' and parents' expectations of orthodontic treatment in university settings

INTRODUCTION

The primary aim was to compare patients' and parents' orthodontic treatment expectations at the Eastman Institute for Oral Health, University of Rochester, Rochester, NY (UR) in the United States. Secondary aims were to assess the association between sociodemographic factors and UR participants' expectations; and compare participants' expectations between UR, Academic Centre for Dentistry Amsterdam (ACTA) and King's College Dental Hospital, London, United Kingdom (KC) (previously published data).

METHODS

One hundred and forty participants [70 patients and one of their parents (n = 70)] completed a validated questionnaire (10 questions) to measure orthodontic treatment expectations before screening at the Orthodontic Department at UR. Various sociodemographic factors were assessed. The paired t test (for continuous responses) and the Fisher exact test (for categorical responses) were used to compare UR patients' and parents' responses. Two-sample t test and the Fisher exact test were used to compare participants' responses among sociodemographic groups. One-way analysis of variance followed by the Tukey test, and the Fisher exact test were used to compare participants' responses between UR, and ACTA and KC (data collected from previous publications). A multiplicity correction was performed to control the false discovery rate.

RESULTS

Patients at UR expected less check-up and diagnosis, and less discussion about treatment at the initial visit, more dietary restrictions, and less improvement in smile esthetics and social confidence with orthodontic treatment than parents. Participants' responses differed by sociodemographic factors at UR and between UR, ACTA, and KC.

CONCLUSIONS

Expectations of orthodontic treatment differ between patients and their parents, are associated with sociodemographic factors, and vary among United States and European University centers.

Orthodontic debonding and tooth sensitivity of anterior and posterior teeth

OBJECTIVES

To assess whether orthodontic debonding and onset of tooth sensitivity were related and if anterior and posterior teeth showed different sensitivity.

MATERIALS AND METHODS

40 patients were divided into a trial group (group 1, at the end of the multibracket treatment) and a control group (group 2, not under treatment). After the application of compressed air and cold water to mandibular incisors and first molars, participants were asked to report the pain felt for each tooth using a 100-mm visual analogue scale. In group 1, assessment was performed just before debonding (T0), immediately after completion of debonding (T1) and 7 days after (T2). In group 2, values were assessed at the beginning of a follow-up visit (T0), at the end of the same visit (T1) and 7 days after (T2).

RESULTS

Considering overall teeth, statistical analyses showed significantly higher values in the trial group at T1 after both stimuli, especially after cold water, besides a significant difference between T0 and T2 values in the same group. Anterior teeth showed significantly higher VAS scores than posterior after the two thermal stimuli, except after air stimulation in group 1 at T2 and in group 2.

CONCLUSIONS

Orthodontic debonding leads to sensitivity to thermal stimuli especially in the anterior teeth, however pain level is restored within 7 days.

Effect of experimental orthodontic pain on gray and white matter functional connectivity

Aim

Over 90% of patients receiving orthodontic treatment experience clinically significant pain. However, little is known about the neural correlates of orthodontic pain and which has therefore been investigated in the present study of healthy subjects using an experimental paradigm.

Methods

Resting‐state functional magnetic resonance imaging (rsfMRI) was performed in 44 healthy subjects 24 hours after an elastic separator had been introduced between the first and the second molar on the right side of the lower jaw and in 49 age‐ and sex‐matched healthy control (HC) subjects. A K‐means clustering algorithm was used to identify functional gray matter (GM) and white matter (WM) resting‐state networks, and differences in functional connectivity (FC) of GM and WM between the group of subjects with experimental orthodontic pain and HC were analyzed.

Results

Twelve GM networks and 14 WM networks with high stability were identified. Compared with HC, subjects with orthodontic pain showed significantly increased FC between WM12, which includes posterior thalamic radiation and posterior cingulum bundle, and most GM networks. Besides, the WM12 network showed significant differences in FC with three GM‐WM loops involving the default mode network, dorsal attention network, and salience network, respectively.

Conclusions

Orthodontic pain is shown to produce an alteration of FC in networks relevant to pain processing, which may be mediated by a WM network relevant to emotion perception and cognitive processing.

Effectiveness of animal-assisted therapy on pain in children: A systematic review and meta-analysis

Aims

Animal-assisted therapy (AAT) relieves pain by creating a relaxed and comfortable environment to reduce anxiety in children. Yet little is known about its effects on pain in children. This study aims to systematically evaluate the effects of AAT on pain in children.

Methods

Eight databases including PubMed, Cochrane Library, Web of Science, CINAHL Complete, Chinese Biomedical Database (CBM), Weipu Database (VIP), China Knowledge Resource Integrated Database (CNKI) and Wanfang Database were retrieved, and all randomized controlled trials or controlled clinical trial using AAT on children’s pain were recruited from inception to October 2019. Two reviewers independently screened literature, extracted data and assessed the risk of bias of the included studies. RevMan 5.3 software was employed for meta-analysis.

Results

Seven published studies containing 4 RCTs and 3 CCTs were included for the systematic review. The results of meta-analysis showed that AAT could reduce children’s pain when compared with the control group [MD = −0.53, 95% CI (−0.77, −0.30), P < 0.00001].

Conclusion

Current evidence shows that AAT can relieve pain in children to some extent. Considering the limited quality and quantity of the available studies, more high quality studies should be performed to verify the above conclusion.

Accelerated orthodontics: Getting ahead of ourselves?

There is disagreement as to what constitutes an acceptable duration for orthodontic treatment but seeming unanimity that acceleration is required. This contention has spawned a range of surgical and non-surgical adjuncts designed to accelerate orthodontic tooth movement, geared at reducing overall treatment times while maintaining optimal occlusal results. Largely, however, marketed non-surgical adjuncts and involved surgical procedures have shown equivocal effectiveness in reducing treatment times. Notwithstanding this, a range of key treatment decisions and approaches may have a more potent effect. While external solutions may offer alluring possibilities, perhaps, more mundane realities including refinement of orthodontic planning and decision-making with efficiency and process, as well as final outcome, in mind continue to offer the most accessible and influential means of improving orthodontic efficiency?

Pain and Oral-Health-Related Quality of Life in Orthodontic Patients During Initial Therapy with Conventional, Low-Friction, and Lingual Brackets and Aligners (Invisalign): A Prospective Clinical Study

The aim of this study was to compare pain and its relationship with the oral quality of life of patients with different types of orthodontic appliances: conventional and conventional low-friction brackets, lingual brackets, and aligners. A prospective clinical study was carried out with a sample size of 120 patients (54 men, 66 women) divided into 4 groups of 30 patients each. The modified McGill questionnaire was used to measure pain at 4, 8, and 24 h and 2, 3, 4, 5, 6, and 7 days after the start of treatment, and the Oral Health Impact Profile-14 (OHIP-14) questionnaire was used to measure the oral-health-related quality of life (OHRQoL) in the first month of treatment. The maximum peak of pain was obtained between 24 and 48 h of treatment. It was found that patients in the lingual orthodontic group described lower levels of pain at all times analyzed, and their scores in the total OHIP-14 indicated less impact on their oral quality of life (1.3 ± 1.2, p < 0.01) compared with the other groups analyzed. There was little difference with the aligners group (Invisalign) (1.7 ± 1.9, p < 0.01). The technique used influences the pain and quality of life of patients at the start of orthodontic treatment.

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.

Vesicular nucleotide transporter mediates adenosine triphosphate release in compressed human periodontal ligament fibroblast cells and participates in tooth movement-induced nociception in rats

OBJECTIVE

Pain control is imperative in orthodontic treatment. Adenosine triphosphate (ATP) is a key mediator released from periodontal ligament cells that excites nociceptive nerve endings. Vesicular nucleotide transporter (VNUT), encoded by the Solute carrier family 17 member 9 (SLC17A9) gene, participates in ATP uptake into secretory vesicles; thus, it may mediate tooth movement-induced pain. In the present study, we examined whether VNUT in periodontal ligament cells participates in tooth movement-induced nociception.

DESIGN

Expression levels of SLC17A9, connexin 43, and pannexin 1 in human periodontal ligament fibroblasts (HPDLFs) were examined by quantitative reverse transcription-polymerase chain reaction. Mechanical force via centrifugation-induced ATP release was measured using an ATP bioluminescence assay. Inhibitors were used to evaluate the role of ATP transporters. Face-grooming behaviors were assessed as indicators of nociceptive responses after experimental tooth movement in rats, as well as the effects of drugs for the pain-like behavior.

RESULTS

After HPDLFs underwent mechanical stimulation by centrifugation, SLC17A9 mRNA expression in the cells was significantly upregulated. Increased ATP release from HPDLFs after mechanical stimulation was suppressed by treatment with clodronic acid, a VNUT inhibitor, at concentrations of 0.1 and 1.0 μM. In rats, face-grooming behaviors (indicators of nociception) were significantly increased on day 1 after experimental tooth movement. Increased face-grooming behaviors were suppressed by systemic administration of clodronic acid (0.1 mg/kg).

CONCLUSIONS

These results indicate that release of ATP from periodontal ligament cells via VNUT is important for nociceptive transduction during orthodontic treatment. Thus, VNUT may provide a novel drug target for tooth movement-induced pain.