Artigo2020_Nayara_JOR_2

Prévia do material em texto

This article has been accepted for publication and undergone full peer review but has not been 
through the copyediting, typesetting, pagination and proofreading process, which may lead to 
differences between this version and the Version of Record. Please cite this article as doi: 
10.1111/JOOR.13130
 This article is protected by copyright. All rights reserved
PROF. PAULO CÉSAR RODRIGUES CONTI (Orcid ID : 0000-0003-0413-4658)
PROF. LEONARDO RIGOLDI BONJARDIM (Orcid ID : 0000-0002-0080-7678)
PROF. ANA CLÁUDIA DE CASTRO FERREIRA CONTI (Orcid ID : 0000-0001-9658-1652)
Article type : Original Article
Frequency of awake bruxism behavior in orthodontic patients: randomized clinical 
trial
Awake bruxism behavior in orthodontic patients
Authors: Nayara Caldas Pereira1, Paula Vanessa Pedron Oltramari2, Paulo César 
Rodrigues Conti3, Leonardo Rigoldi Bonjardim4, Renata Rodrigues de Almeida-Pedrin2, 
Thaís Maria Freire Fernandes2, Marcio Rodrigues de Almeida2, Ana Cláudia de Castro 
Ferreira Conti2
1 Postgraduate Student, Department of Orthodontics, University of North Paraná 
(UNOPAR), Londrina-PR, Brazil.
2 Full Professor, Department of Orthodontics, University of North Paraná (UNOPAR), 
Londrina-PR, Brazil.
3 Full Professor, Department of Prosthodontics, Bauru School of Dentistry, University of 
São Paulo, Brazil, Bauru Orofacial Pain Group.A
cc
ep
te
d 
A
rt
ic
le
https://doi.org/10.1111/JOOR.13130
https://doi.org/10.1111/JOOR.13130
https://doi.org/10.1111/JOOR.13130
http://crossmark.crossref.org/dialog/?doi=10.1111%2Fjoor.13130&domain=pdf&date_stamp=2020-12-05
This article is protected by copyright. All rights reserved
4 Full Professor, Section of Head and Face Physiology, Department of Biological 
Sciences, Bauru School of Dentistry, University of São Paulo, Brazil, Bauru Orofacial 
Pain Group.
ACKNOWLEDGMENTS
This study was funded by CAPES
ABSTRACT
Introduction: The influence of aligners on the activity of the masticatory muscles is still 
controversial, especially regarding the behavior associated with awake bruxism (AB).
Objective: To compare the frequency of AB behaviors between patients treated with 
aligners and fixed appliances. 
Methods: The sample comprised 38 Class I patients (mean age 22.08 years), divided by 
simple randomization into two groups: OA group; orthodontic aligners (n 19) and FA 
group; fixed appliance (n 19). The frequency of AB was investigated by the ecological 
momentary assessment using an online device (mentimeter), during 7 following days at A
cc
ep
te
d 
A
rt
ic
le
This article is protected by copyright. All rights reserved
different timepoints, before and after appliance placement and in the 2nd, 3rd, 4th and 6th 
months of orthodontic treatment. These variables were also evaluated: level of anxiety by 
the State-Trait Anxiety Inventory, stress by the Perceived Stress Scale, catastrophizing 
related to pain and degree of hypervigilance by the Pain Vigilance and Awareness 
Questionnaire, and the presence of facial pain evaluated by the DC/TMD. 
Results: There was no difference between groups in the frequency of AB behaviors, with 
mean of 53.5% for group OA and 51.3% for FA. The most frequent behavior was slightly 
touching the teeth, and in FA group there was a significant reduction in this behavior 
soon after appliance placement. The groups did not differ concerning the degree of 
anxiety, stress, catastrophizing, hypervigilance and facial pain. 
Conclusion: The orthodontic treatment performed with aligners or fixed appliances did 
not influence the frequency of AB during the 6 months of treatment. 
Registry of Clinical Trials (REBEC): RBR-9zytwf
Key words: Orthodontics, Aligners, Fixed appliance, Awake bruxism
1- BACKGROUND
Bruxism is defined as the activity of masticatory muscles occurring during sleep 
(characterized as rhythmic or non-rhythmic) or awake (characterized by repetitive or 
sustained contact of teeth), which should be considered separately.1 Awake bruxism (AB) A
cc
ep
te
d 
A
rt
ic
le
This article is protected by copyright. All rights reserved
may be associated with several psychosocial factors, such as anxiety,2,3 stress3,4 and 
hypervigilance,5 and its most important effects are tooth wear, orofacial pain symptoms, 
periodontal disease, tooth fracture and/or breakage of dentures.2
Most studies have focused on the study of sleep bruxism (SB),6,7 while knowledge 
about awake bruxism is still fragmented.6 The prevalence of AB in adults varies from 22% 
to 30% and SB from 1% to 15%.7 This high prevalence of AB affects more than one third 
of the population, especially young adult individuals, which is considered an age group 
frequently present in orthodontic practices.8
It should be noted that, in recent years, the use of orthodontic aligners (OA) has 
increased significantly mainly to meet the demand of young adult patients with great 
esthetic needs. The clinical efficiency of these appliances associated with comfort in 
relation to traditional fixed appliances (FA) have been identified as contributing factors for 
their large-scale use.9,10
Studies have investigated the clinical efficacy of aligners and their effects on root 
resorption,11 periodontal health,12 perception of pain and discomfort.10 It has been 
reported that orthodontic aligners could be an alternative option for orthodontic treatment 
in patients with temporomandibular disorder (TMD)13 and sleep bruxism.9 Its possible 
effects on bruxism are still unknown, and evidence on the possible effects of aligners on 
the activity of masticatory muscles is still limited and controversial.14 There is still lack of 
scientific evidence demonstrating the effects of aligners on intraoral perception and AB 
behavior.
Thus, this clinical study had as primary objective to compare the frequency of 
bruxism behavior while awake, during the initial stages of orthodontic treatment, 
comparing two types of orthodontic appliances (fixed and aligners). The levels of anxiety, 
stress, degree of hypervigilance and catastrophizing related to pain and presence of 
facial pain symptoms were also compared.
2- METHODS
- Participants 
Overall, from 2,662 individuals, 40 patients were selected in this randomized 
parallel clinical trial study meeting the criteria: (1) age between 13 and 35 years; (2) both A
cc
ep
te
d 
A
rt
ic
le
This article is protected by copyright. All rights reserved
genders; (3) Angle Class I malocclusion; (4) moderate lower anterior crowding (3 to 6 
mm); and (5) treatment without extraction. The exclusion criteria were: (1) missing 
permanent teeth, except for the third molars; (2) anterior or posterior open bite; (3) 
anterior or posterior crossbite; (4) history of orthodontic treatment and (5) signs or 
symptoms of TMD or other painful chronic disorder based on the recommendations of the 
“Diagnostic Criteria for TMD (DC/TMD)”15. Written consent was obtained from all patients 
before the study. This study was approved by the Institutional Review Board of University 
of North Paraná (UNOPAR) under CAAE n. 12088219.0.0000.0108 and received the 
number (RBR-9zytwf) in the Brazilian Registry of Clinical Trials (REBEC).
- Interventions
For all patients included in the sample, initial orthodontic records were obtained 
including intra- and extraoral photographs; dental casts; periapical radiographs of upper 
and lower incisors; cone beam computed tomography (CBCT) and digital intraoral 
scanning (3D model) using an intraoral scanner (iTero® Intraoral Element Scanner).
The participants were randomly divided into 2 groups by simple randomization for 
the factors gender, age, amount of crowding (Little’s irregularity index) and severity of 
malocclusion (PAR index):
- Group OA (n=20) treated with Invisalign orthodontic aligners from Align 
Technology (Santa Clara, California, USA). The 3D planning was performed using the 
software ClinCheckTM Pro version 5,6 following thepatients’ needs and manufacturer's 
guidelines, and the aligners were changed at every 10 days.
- Group (FA) was also composed of 20 patients treated with fixed appliances (slot 
0.022 x 0.030”, 3M Unitek, Monrovia, Calif). The appliances were placed up to the 
second molars following the same sequence of Nitinol wires (0.014”, 0.016”, 
0.016x.022”), respecting the individual needs of each patient. Orthodontic appointments 
were performed once a month by 2 orthodontic master program students at the post-
graduate clinics under supervision of an orthodontist with more than 15 years of 
experience.
- Outcome Measurement A
cc
ep
te
d 
A
rt
ic
le
This article is protected by copyright. All rights reserved
To allow real-time evaluation of the frequency of awake bruxism behavior, the 
ecological momentary assessment (EMA) was used collecting self-reports of episodes of 
this parafunction, in their natural environment.16 Each participant was instructed to 
recognize various AB-related behaviors by links sent by WhatsApp using a web based 
survey program called Mentimeter®. Aiming to allow the study participants to get used to 
this assessment, test links were sent for training how to use the research instrument one 
day before the study beginning.
The link directed the patient to the question about the contact condition between 
teeth suggesting some behavior related to bruxism during wakefulness, based on 
previous studies: “Which option below best describes the contact of your teeth?”. The 
possible responses were: a) I am not touching my teeth; b) I am not touching my teeth, 
but I feel my muscles are contracted; c) I am slightly touching my teeth; d) I am clenching 
my teeth; or e) I am grinding my teeth. Each link was available for response for 5 minutes 
from the moment of the alert sound. After this period, the system was blocked to record 
responses. A total of 10 links were sent per day, for 7 consecutive days in the following 
periods: baseline, soon after appliance placement, in the first, second, third and sixth 
months after appliance placement.17,18
The questions were sent by the researcher at random times to avoid the risk that 
individuals modify their behavior based on the expectation of alert. The recording time 
was set between 8:00 to 20:00. A minimum of 70% of responses was considered 
necessary to validate them; in case of failure to reach this percentage, an additional 
recording day was defined to complete this protocol.
The variables that might impact the AB behavior were also assessed at baseline 
as anxiety by the State-Trait Anxiety Inventory (STAI-T),19 stress by the Perceived Stress 
Scale (PSS 14),20 and catastrophizing by the pain catastrophizing scale (PCS)21 and the 
degree of hypervigilance by the Pain Vigilance and Awareness Questionnaire (PVAQ).22 
The presence of facial pain was also investigated using the DC/TMD symptoms 
questionnaire.15 Additionally, stress and the presence of pain were also investigated in 
the first, second, third and sixth months after appliance placement.
Sample SizeA
cc
ep
te
d 
A
rt
ic
le
This article is protected by copyright. All rights reserved
An analysis of the power of the test showed that based on the average standard 
deviation of the AB frequency variation (32.1), a sample of at least 19 patients would 
have an 80% probability of detecting a real difference of 30 percentage points between 
the groups, with a significance level of 5%.
Randomization
Simple randomization was performed by an external investigator, using a software 
(Excel 2007, Microsoft Windows, Microsoft, Chicago, IL, USA), at a ratio of 1:1. This 
investigator inserted the randomization codes in numbered, sealed and opaque 
envelopes, consecutively, assuring blinded allocation into 2 groups.
Blinding
The blinding of patient and operator was not possible in this study. However, the 
results were analyzed in a blind manner, assigning a code number to the patients and 
group with aligners as OA Group, and fixed appliances as FA Group.
- Statistical analysis
Statistical analysis was performed by an investigator not related to the study. All 
quantitative measurements were analyzed using the Kolmogorov-Smirnov normality test. 
Comparison between the OA and FA groups in the quantitative variables was performed 
by the t test for independent groups, and the proportion of occurrence of pain was 
analyzed by the Fisher exact test. Regarding the frequency of AB, comparison between 
the six periods, within each group, was performed by the Friedman test, and comparison 
between the two groups in each period was performed by the Mann-Whitney test. 
All tests were performed at a significance level of 5% (p<0,05). All statistical 
procedures were performed on the software SPSS version 26.
3- RESULTS
3.1 Participants flow and baseline data A
cc
ep
te
d 
A
rt
ic
le
This article is protected by copyright. All rights reserved
Figure 1 shows the flowchart of patients evaluated for study eligibility, 
randomization, allocation, treatment and follow-up on the first 6 months of orthodontic 
treatment. Participants who met the established criteria were recruited from August 2018 
to February 2019. Forty individuals were recruited, divided into 2 groups of 20 patients. 
One participant from each group was excluded from the sample due to non-compliance in 
answering the questions (group FA) and due to a trip abroad at baseline (group OA). 
Thus, data from a total of 38 patients were analyzed. According to Table 1 the two groups 
matched for gender (p=1.000), age (p=0.0681), PAR index (p=0.8751) and Little's 
irregularity index (p=0.5705). At baseline, the groups did not differ regarding anxiety, 
catastrophizing, hypervigilance, stress and facial pain. 
3.2 Outcome data
Evaluation of frequency of awake bruxism
The mean percentage of valid responses in the study was 71.52%, being 72.88% 
for group OA and 70.16% for group FA.
Regarding the mean frequency of AB, considering all types of behavior, group OA 
maintained a more constant frequency, with 55.9% at T0, 56% T1, 50.2% at T2, 52.2% at 
T3, 52.4% at T4 and in 54.1% at T5. Conversely, group FA had a mean frequency at T0 
(baseline) of 61.4%, and then this frequency showed a decrease, namely 44.4% at T1, 
47.7% at T2, 46.1% at T3 and 46.3% at T4, rising again at T5 to 61.8% (Table 2 and 
Figure 2). 
Concerning the different habits that comprised the diagnosis of AB, the most 
prevalent in groups OA and FA was to slightly touch the teeth (40.1% and 38.4%), 
clenching the teeth (9.5% and 7.6%), without dental contact but with contracted muscles 
with 3.2% and 4.9%, and grinding the teeth with 0.7% and 0.4%, respectively (Table 2).
With regard to the variation in the frequency of AB in each evaluation period 
compared to the baseline (T0), there was no statistically significant difference between 
the groups (P<0.05) (Table 3).
A
cc
ep
te
d 
A
rt
ic
le
This article is protected by copyright. All rights reserved
Regarding the most frequent behavior (slightly touching the teeth), an increase was 
observed right after appliance placement (T1) from 36.6% to 42.7% in group OA, 
gradually decreasing in the following periods. In group FA, a statistically significant 
decreasing shortly after placement (T1) from 45.1% to 25.6% was observed, rising in the 
following periods (Table 4).
Harms
There were no harms during the follow-up of the two groups between time points.
4- DISCUSSION
The AB has higher prevalence in the adult population than SB;6,7 however, much 
of the scientific evidence obtained so far is related to SB. Among the strategies to control 
the activity of masticatory muscles during sleep, the use of interocclusal devices has 
been indicated, even though this remains controversial in the literature.23 In this context, 
appliances made of different material than rigid or resilient occlusal plates, such asorthodontic aligners, called the attention of researchers.14,24 Although the use of these 
appliances does not seem to influence the SB,14 no study has investigated the effect of 
these aligners in relation to AB. Thus, this study compared the frequency of AB behavior 
among patients starting orthodontic treatment with aligners and conventional fixed 
appliances. Our results showed that the type of orthodontic appliance does not seem to 
influence the activity levels of awake bruxism, considering all different types of 
parafunctional behavior. However, the “light contact” behaviors presented significant 
different frequencies between groups after appliance placement.
The groups were matched at baseline for age, gender, amount of crowding and 
severity of malocclusion. Also, at baseline, the intergroup results concerning the degree 
of anxiety, stress, hypervigilance, pain catastrophizing and facial pain showed similarity 
between groups. This “baseline” facial pain was mostly mild in both groups and did not 
meet the DC criteria for TMD. The similarity between groups was preserved throughout 
the period of evaluation, and therefore did not interfere with the study’s outcomes. The 
control of these variables is fundamental, since several authors have already related AB A
cc
ep
te
d 
A
rt
ic
le
This article is protected by copyright. All rights reserved
to anxiety,2,3 stress,3,4 and hypervigilance.5 The combination of these factors seems to be 
additive, non-adaptive and may lead to an increase in the individual's likelihood to 
develop oral parafunctions and facial pain.25
Most reports in the literature about the frequency of AB were obtained by cross-
sectional and retrospective self-reports;8 however, due to the risk of memory bias of 
patients and lack of information on their frequency, other diagnostic means were 
developed.17,26 In order to minimize the risk of bias, we assess AB frequency applying the 
EMA as reported in most recent studies.6,17,18,26 Sending questions in links by WhatsApp 
allowed checking the frequency of AB in real time for the two groups during the first six 
months of the orthodontic treatment. The association of the web-based survey program 
(mentimeter) with popular social media is an interesting and easy way for the 
implementation of EMA in researches.
The mean total response rate to the 10 alerts sent was 71.52%, being similar 
between the two groups: 72.88% for group OA and 70.16% for group FA. These values 
were lower than the mean response rate of 82.1±9.2% from 15 alerts per day found in 
another study,17 yet they are in agreement with the mean compliance rate per day of 60% 
of alerts, with a minimum of 12 daily alerts.6
The evaluation of AB behaviors in this follow-up period of 6 months resulted in a 
mean total frequency of 53.5% and 51.3% for groups OA and FA, respectively. It can be 
noticed that the frequency was similar between groups, regardless of the type of 
orthodontic appliance used (Table 2). Other studies also reported the mean frequency of 
AB in a sample of healthy young adults (non-orthodontic patients), dental students, and 
observed frequencies of 28.3%17 and 48%,18 both related to data collected for seven 
consecutive days using EMA strategy, applying the BruxAppR (BruxApp Team, 
Pontedera, Italy). In the latter, that value of 48% at baseline decreased to 26% after one 
month.18 A similar AB frequency was found in another study, 49% of the sample (114 
patients) beginning orthodontic treatment self-reported awake bruxism behavior.27 
When the frequency of AB behavior was analyzed between groups, there was no 
significant variation in this frequency comparing each period to the baseline data (Table 
3). Therefore, the frequency of AB did not differ, regardless of the type of appliance used. A
cc
ep
te
d 
A
rt
ic
le
This article is protected by copyright. All rights reserved
The paucity of the available literature regarding the influence of the type of orthodontic 
treatment on the frequency of AB make it impossible to have comparison parameters. 
Concerning the effects of aligners with episodes of SB, a tendency to increase in SB after 
the first and third months of treatment has been reported,14 in contrast to another study 
which revealed that, after the first month of treatment, the patients showed a significant 
reduction in the number of SB episodes, and after three months the values returned to 
baseline levels.9 To date, there is no pre-established standard or cut-off value to define 
who has or does not have AB. In addition, many types of oral habits are part of this 
behavior, which complicates the analysis and interpretation of data.
When considered a specific type of behavior, the habit of slightly touching the 
teeth and clenching the teeth were the conditions most frequently reported, with a total 
mean frequency of 40.1% and 9.5% in group OA, and 38.4% and 7.6% in group FA. 
Lower prevalence values (14.5% for touching the teeth and 3.7% for clenching the teeth) 
were reported in samples of individuals not undergoing orthodontic treatment.17 In 
another study, 20% of participants answered that the teeth were in contact, 14% with 
mandibular clenching, 3% reported clenching the teeth, 1% grinding the teeth, and a 
month later these values were 11%, 13%, 2% and 1%, respectively.18
Although the methodology used to characterize the frequency of AB in this study 
considered the frequency of four behaviors, higher values were found for the “slightly 
touching the teeth” from the baseline, regardless of the type of appliance. Possibly, such 
differences can be explained by the use of an online evaluation technique and by directly 
sending the questions: "What option below best describes the contact of your teeth?" 
Other studies employing different methods without suggesting this possible teeth contact, 
may not stimulate their attention to this behavior.17,18 However, regardless of the 
recording method, it should be noted that the same behavior has been reported as more 
prevalent in individuals with complaints of chronic pain related to TMD.28
It is interesting to note that, although no differences were found in the inter group 
analysis for this behavior, the intra group evaluation has shown a significant decrease in 
its frequency right after appliance placement (T0-T1), from 45.1% to 25.6% in FA group 
(Table 4). Conversely, the OA group showed a constant habit frequency during the entire 
study.A
cc
ep
te
d 
A
rt
ic
le
This article is protected by copyright. All rights reserved
This aspect deserves some comments. The stimulus caused by FA tends to be 
more impacting on the system, in general, based on the presence of brackets, wires, and 
all the discomfort caused by the apparatus. At first, this sudden intraoral new condition 
might alter the individuals’ sensory perception, leading to a natural and unconscious 
protection against it, leading to decreasing the behavior. This condition, however, is lost 
after the patient becomes used to the new intraoral condition, returning to the baseline 
parameters, before the appliance placement. For OA group, this effect does not seem to 
exist, i.e. the interocclusal insertion of a thin plate does not seem to change the initial 
frequency of light touch behavior reported by EMA.
Considering that the groups did not differ in the initial levels of anxiety, stress, 
hypervigilance, catastrophizing and reports of facial pain, we can infer that possibly the 
awake bruxism behavior in these patients could be influenced only by the presence of 
orthodontic appliances. Thus, this pioneer study contributed to understand a little more 
about the impact of orthodontic therapy over the initial phase of treatment.
Limitations 
As a limitation of our study it should be highlighted that the sample was composed 
of young individuals, other age ranges might be investigated as well.
GeneralizabilityGeneralization of the outcomes should be performed with caution as the 
patients were healthy and young. 
4-CONCLUSION
The type of orthodontic appliance (orthodontic aligners or conventional fixed 
appliances) did not influence the frequency of awake bruxism behavior during the initial 
stages of orthodontic treatment, although the behavior of slightly touching the teeth 
seems to be reduced right after placement of FA. Yet, the most common behaviors were 
slightly touching the teeth and clenching the teeth.A
cc
ep
te
d 
A
rt
ic
le
This article is protected by copyright. All rights reserved
All authors declare no conflict of interests.
REFERENCES
1. Lobbezoo F, Ahlberg J, Raphael KG, Wetselaar P, Glaros AG, Kato T, et al. 
International consensus on the assessment of bruxism: Report of a work in progress. J 
Oral Rehabil. 2018; 45 (11): 837-844.
2. Endo H, Kenemura K, Tanabe N e Takebe J. Clenching occurring during the day is 
influenced by psychological factors. J Prosthodont Res. 2011; 55 (3): 159–164.
3. Ordonez-Plaza MP, Villavicencio-Caparó E, Alvarado-Jiménez OR, Vanegas-
Alvecillas ME. Prevalencia de bruxismo de vigilia evaluado por auto-reporte en relación 
con estrés, ansiedad y depresión. Rev Estomatol Herediana. 2016; 26 (3):147-150.
4. Rao SK, Bhat M, David J. Work, Stress, and Diurnal Bruxism: A Pilot Study among 
Information Technology Professionals in Bangalore City, India. Int J Dent. 2011; 2011: 00
5. Michelotti A, Cioffi I, Landino D, Galeone C, Farella M. Effects of Experimental 
Occlusal Interferences in Individuals Reporting Different Levels of Wake-Time 
Parafunctions. J Orofac Pain. 2012; 26 (3):168–175.
6. Colonna A, Lombardo L, Siciliani G, Bracci A, Guarda-Nardini L, Djukic G, et al. 
Smartphone-based application for EMA assessment of awake bruxism: compliance 
evaluation in a sample of healthy young adults. Clin Oral Investig. 2019; 00: 00.
7. Melo G, Duarte J, Pauletto P, Porporatti AL, Stuginski-Barbosa J, Winocur E, et al. 
Bruxism: An umbrela review of systematic reviews. J Oral Rehabil. 2019; 46 (7): 666–
690. 
A
cc
ep
te
d 
A
rt
ic
le
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3235458/
https://www.ncbi.nlm.nih.gov/pubmed/?term=Smartphone-based+application+for+EMA+assessment+of+awake+bruxism%3A+compliance+evaluation+in+a+sample+of+healthy+young+adults
This article is protected by copyright. All rights reserved
8. Manfredini D, Winocur E, Guarda-Nardini L. Paesani D, Lobbezoo F. Epidemiology 
of bruxism in adults: A systemic review of the literature. J Orofac Pain. 2013; 27 (2): 99-
110
9. Bargellini A, Castroflorio T, Casasco F, Giacone M, Garino F, Cugliari G, et al. 
Short Term Evaluation of the Effects of Orthodontic Clear Aligners on Sleep Bruxism 
Activity. Iran J Ortho. 2017; 12(2):7916-7920.
10. Fujiyama K, Honjo T, Suzuki M, Matsuoka S, Deguchi T. Analysis of pain level in 
cases treated with Invisalign aligner: comparison with fixed edgewise appliance therapy. 
Prog Orthod. 2014; 15 (1) :64-70.
11. Fang X, Qi R, Liu C. Root resorption in orthodontic treatment with clear aligners: A 
systematic review and meta-analysis. Orthod Craniofac Res. 2019;22(4):259-269.
12. Jiang Q, Li J, Mei L, Du J, Levrini L, Abbate GM. Periodontal health during 
orthodontic treatment with clear aligners and fixed appliances. J Am Dent 
Assoc. 2018;149(8):712-720.
13. Schupp W, Haubrich J, Neumann I. Invisalign treatment of patients with 
craniomandibular disorders. Int Orthod. 2010; 8(3): 253-267.
14. Castroflorio T, Bargellini A, Luccchese A, Manuelli M, Casasco F, Cugliari G, Cioffi 
I e Deregibus A. Effects of Clear Aligners on Sleep Bruxism: Randomized Controlled 
Trial. Journal of Biological Regulators e Homeostaticagents. J Biol Regul Homeost 
Agents. 2018; 32(2): 21-29.
15. Schiffman E, Ohrbach R, Truelove E, Look J, Anderson G, Goulet JP, et al. 
Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) for Clinical and 
Research Applications: recommendations of the International RDC/TMD Consortium 
Network and Orofacial Pain Special Interest Group. J Oral Facial Pain 
Headache. 2014;28(1):6-27.
A
cc
ep
te
d 
A
rt
ic
le
https://www.ncbi.nlm.nih.gov/pubmed/?term=Fang%20X%5BAuthor%5D&cauthor=true&cauthor_uid=31323701
https://www.ncbi.nlm.nih.gov/pubmed/?term=Qi%20R%5BAuthor%5D&cauthor=true&cauthor_uid=31323701
https://www.ncbi.nlm.nih.gov/pubmed/?term=Liu%20C%5BAuthor%5D&cauthor=true&cauthor_uid=31323701
https://www.ncbi.nlm.nih.gov/pubmed/31323701
https://www.ncbi.nlm.nih.gov/pubmed/29921415
https://www.ncbi.nlm.nih.gov/pubmed/29921415
https://www.ncbi.nlm.nih.gov/pubmed/?term=Effects+of+Clear+Aligners+on+Sleep+Bruxism%3A+Randomized+Controlled+Trial.
https://www.ncbi.nlm.nih.gov/pubmed/?term=Effects+of+Clear+Aligners+on+Sleep+Bruxism%3A+Randomized+Controlled+Trial.
https://www.ncbi.nlm.nih.gov/pubmed/24482784
https://www.ncbi.nlm.nih.gov/pubmed/24482784
This article is protected by copyright. All rights reserved
16. Manfredini D, Bracci A, Djukic G. BruxApp: The Ecological Momentary 
Assessment of Awake Bruxism. Minerva Stomatol. 2016; 65 (4):252-255.
17. Bracci A, Djukic G, Favero L, Salmaso L, Guarda-Nardini L, Manfredini D. 
Frequency of awake bruxism behaviours in the natural environment. A 7-day, multiple-
point observation of real-time report in healthy young adults. J Oral Rehabil. 
2018;45(6):423-429.
18. Zani A, Lobbezoo F, Bracci A, Ahlberg J, Manfredini D. Ecological Momentary 
Assessment and Intervention Principles for the Study of Awake Bruxism Behaviors, Part 
1: General Principles and Preliminary Data on Healthy Young Italian Adults. Front. 
Neurol. 2019; 10:169-174.
19. Spielberger C D., Gorsuch R, Lushene RE. Manual for the State-Trait Anxiety 
Inventory. Palo Alto, CA, USA: Consulting Psychologist Press; 1970.
20. Cohen S, Karmack T, Mermelsteinm R. A global measure of perceived stress. J 
Health Soc Behav. 1983;24(4):385-96. 
21. Flor H, Behle DJ, Birbaumer N. Assessment of pain-related cognitions in chronic 
pain patients. Behav Res Ther. 1993;31(1):63-73.
22. Roelofs J, Peters ML, McCracken L, Vlaeyen JW.The pain vigilance and 
awareness questionnaire (PVAQ): further psychometric evaluation in fibromyalgia and 
other chronic pain syndromes. Pain. 2003; 101(3):299-306.
23. Manfredini D, Ahlberg J, Winocur E, Lobbezoo F. Management of sleep bruxism in 
adults: a qualitative systematic literature review. J Oral Rehabil. 2015;42(11):862–874.
24. Manfredini D, Lombardo L, Vigiani L, Arreghini A, Siciliani G. Effects of invisible 
orthodontic retainers on masticatory muscles activity during sleep: a controlled trial. Prog 
Orthod. 2018;19(1):24-28.
A
cc
ep
te
d 
A
rt
ic
le
https://www.ncbi.nlm.nih.gov/pubmed/?term=Roelofs%20J%5BAuthor%5D&cauthor=true&cauthor_uid=12583873
https://www.ncbi.nlm.nih.gov/pubmed/?term=Peters%20ML%5BAuthor%5D&cauthor=true&cauthor_uid=12583873
https://www.ncbi.nlm.nih.gov/pubmed/?term=McCracken%20L%5BAuthor%5D&cauthor=true&cauthor_uid=12583873
https://www.ncbi.nlm.nih.gov/pubmed/?term=Vlaeyen%20JW%5BAuthor%5D&cauthor=true&cauthor_uid=12583873
This article is protected by copyright. All rights reserved
25. Ohrbach R, Michelotti A. The Role of Stress in the etiology of oral parafunction and 
myofascial pain. Oral Maxillofac Surg Clin North Am. 2018; 30(3):369-379.
26. Bracci A, Lange M, Djukic G, Guarda-Nardini L, Manfredini D. Ecological 
momentary assessment of awake bruxism behaviors. J Craniomandibular Function. 
2018; 10(3):217-228.
27. Machado NAG, Costa YM, Quevedo HM, Stuginski-Barbosa J, Valle CM, 
Bonjardim LR et al. The association of self-reported awake bruxism with anxiety, 
depression, pain threshold at pressure, pain vigilance, and quality of life in patients 
undergoing orthodontic treatment. J Appl Oral Sci. 2020;28:e2019040. 
28. Sato F, Kino K, Sugisaki M, Haketa T, Amemori Y, Ishikawa T et al. Teeth 
contacting habit as a contributing factor to chronic pain in patients with 
temporomandibulardisorders. J Med Dent Sci. 2006; 53(2):103-109.
A
cc
ep
te
d 
A
rt
ic
le
This article is protected by copyright. All rights reserved
Table 1 – Comparison between the two groups regarding age, Little’s irregularity index, 
Par index, degree of anxiety, stress, hypervigilance, catastrophizing and facial pain, 
before appliance placement.
Variables OA (n=20) FA (n=20) p
Age (years) mean/sd £ 23.60 5.65 20.56 4.51 0.0681 ns
Gender §
Male n(%) 11 60.0 12 (65.0)
Female n (%) 8 40.0 7 35.0
1.0000 ns
Little’s irregularity index 
mean/sd £
4.69 1.35 4.99 1.88 0.5705 ns
PAR index mean/sd £ 7.70 4.66 7.50 3.18 0.8751 ns
Variables OA (n=19) FA (n=19) p
Anxiety mean/sd £ 36.3 6.1 37.4 6.9 0.622 ns
Catastrophizing mean/sd £ 1.4 1.1 1.9 0.9 0.077 ns
Hypervigilance mean/sd £ 50.8 13.5 49.9 11.2 0.825 ns
Stress mean/sd £ 19.4 6.9 21.8 7.4 0.302 ns
Facial pain n(%) ¥ 6 31.6 6 31.6 1.000 ns
£ (Independent t test) 
§ (Chi-square test with Yates’ correction)
¥ (Fisher exact test)
ns (non-significant)
A
cc
ep
te
d 
A
rt
ic
le
This article is protected by copyright. All rights reserved
Table 2 – Description of the proportion of each response related to EMA during the 
evaluation periods for both groups, mean (m) and standard deviation (sd).
T0 T1 T2 T3 T4 T5 Total
Response
m sd m sd m sd m sd m sd m sd m sd
a 44.1 30.9 44.0 28.3 49.8 33.5 47.8 34.8 47.6 35.2 45.9 39.0 46.5 30.4
b 5.9 15.6 2.7 8.1 2.7 10.4 2.8 11.8 2.8 11.2 2.6 11.2 3.2 11.2
c 36.6 26.1 42.7 27.5 41.6 31.5 40.6 29.4 39.8 29.7 39.5 33.6 40.1 26.8
d 12.4 19.1 10.4 14.9 6.0 9.3 8.4 12.7 9.7 16.9 9.8 17.4 9.5 12.6
e 1.0 4.3 0.2 1.0 0.0 0.0 0.4 0.9 0.2 0.7 2.2 9.6 0.7 1.8
OA
b+c
+
d+e
55.9 30.9 56.0 28.3 50.2 33.5 52.2 34.8 52.4 35.2 54.1 39.0 53.5 30.4
a 38.6 31.2 55.6 35.4 52.3 34.7 53.9 33.2 53.7 37.4 38.2 36.7 48.7 30.3
b 6.0 11.6 10.3 17.4 4.4 11.4 4.2 10.9 2.1 5.5 2.3 6.5 4.9 10.0
c 45.1 28.0 25.6 26.7 37.4 33.2 35.1 30.8 33.4 33.0 54.2 34.6 38.4 25.7
d 10.0 9.8 8.0 13.8 6.0 7.4 6.8 14.2 10.4 23.5 4.3 7.3 7.6 9.5
e 0.3 0.9 0.5 1.7 0.0 0.0 0.1 0.4 0.4 0.9 0.9 3.1 0.4 1.0
FA
b+c
+
d+e
61.4 31.2 44.4 35.4 47.7 34.7 46.1 33.2 46.3 37.4 61.8 36.7 51.3 30.3
a- I am not touching my teeth, b- I am not touching my teeth, but I feel my muscles are contracted, c- I am 
slightly touching my teeth, d- I am clenching my teeth, e- I am grinding my teeth
A
cc
ep
te
d 
A
rt
ic
le
This article is protected by copyright. All rights reserved
Table 3 – Comparison between groups of the variation of frequency of AB (responses 
b+c+d+e) between each evaluation period and T0.
OA Group FA GroupResponses
b+c+d+e mean sd CI 95% mean sd CI 95%
p
T1-T0 0.1 26.3 -12.6 to 12.8 -17.0 31.0 -32.0 to -2.1 0.075 ns
T2-T0 -5.7 26.6 -18.5 to 7.1 -13.7 36.4 -31.2 to 3.9 0.445 ns
T3-T0 -3.7 33.6 -19.9 to 12.5 -15.3 33.1 -31.2 to 0.7 0.291 ns
T4-T0 -3.5 34.7 -20.2 to 13.2 -15.1 35.4 -32.1 to 2.0 0.313 ns
T5-T0 -1.8 36.9 -19.6 to 15.9 0.4 26.7 -12.5 to 13.3 0.832 ns
ns – non-statistically significant difference (independent t test)
(b) - I am not touching my teeth, but I feel my muscles are contracted, (c) - I am slightly touching my teeth, 
(d) - I am clenching my teeth, (e) - I am grinding my teeth
A
cc
ep
te
d 
A
rt
ic
le
This article is protected by copyright. All rights reserved
Table 4 – Intra- and intergroup comparison concerning the response “C” between the 6 
evaluation periods
OA Group FA Group
Period
mean sd median mean sd median
p
between groupsA
cc
ep
te
d 
A
rt
ic
le
This article is protected by copyright. All rights reserved
T0 36.6 26.1 37.9 45,1 28,0 44,4 c 0,354
T1 42.7 27.5 35.8 25,6 26,7 18,4 a 0,025*
T2 41.6 31.5 32.8 37,4 33,2 21,9 ab 0,583
T3 40.6 29.4 42.9 35,1 30,8 29,2 bc 0,452
T4 39.8 29.7 31.0 33,4 33,0 27,2 ab 0,563
T5 39.5 33.6 44.4 54,2 34,6 58,8 c 0,181
p between 
periods
0.912 0.001** 
* – statistically significant difference between groups (Mann-Whitney test)
** – statistically significant difference between periods (Friedman test)
Periods with similar letters are not statistically different from each other
Response C - I am slightly touching my teeth
A
cc
ep
te
d 
A
rt
ic
le
This article is protected by copyright. All rights reserved
FIGURE LEGENDS:
Figure 1: Flowchart of patients
Figure 2: Evolution of responses b+c+d+e (b- I am not touching my teeth, but I feel my muscles 
are contracted, c - I am slightly touching my teeth, d - I am clenching my teeth, e- I am grinding 
my teeth), that characterized the behavior of AB in the two groups during the evaluation period. 
A
cc
ep
te
d 
A
rt
ic
le
 
CONSORT 2010 Flow Diagram 
Evaluated for eligibility 
(n=2662) 
Excluded (n= 2622) 
¨ Did not meet the inclusion 
criteria (n=2608) 
¨ Refused to participate (n=14) 
Analyzed (n=19) 
 
Loss due to trip abroad (n=19) 
Orthodontic aligners (OA) 
(n=20) 
Analyzed (n= 20) 
Fixed appliance (FA) 
(n= 20) 
Analyzed (n=20) 
 
 
Allocation 
After placement 
 
Baseline 
Randomization (n= 40) 
Evaluation 
Analyzed (n=19) 
 
Analyzed (n=20) 
 
 
1 month 
 
Analyzed (n=19) 
 
Analyzed (n=20) 
 
 
2 months 
 
Analyzed (n=19) 
 
Analyzed (n=20) 
 
 
3 months 
 
Analyzed (n=19) 
 
Analyzed (n=19) 
Loss because of not responding to 
the questions for 2.5 months 
Loss because of not responding to 
the questions for 2.5 months 
 
 
6 months 
 
Analysis 
 
Analyzed (n=19) 
 
Analyzed (n=19) 
 
joor_13130_f2.tif
This	article	is	protected	by	copyright.	All	rights	reserved
A
cc
ep
te
d 
A
rt
ic
le