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BEHAVIORAL SCIENCE
Prevalence of Bruxism Awareness in a
Sardinian Population

Marcello Melis, D.M.D., R.Pharm.; Youssef S. Abou-Atme, D.D.S., M.S.
ABSTRACT: 1014 subjects on the island of Sardinia (Italy) were interviewed regarding the habit ofclenching and grinding their teeth. They had to specify if this activity occurred during the day, during thenight, or both. Other information recorded was their age, gender, marital status, and occupation. Overallprevalence of bruxism was 27.2% (276 subjects). No association was found between bruxism and age, gender and job. Even differentiating diurnal, nocturnal, diurnal and nocturnal bruxism, associations were 000$05.00/0, THE JOURNAL OF non-significant. Marital status seems to make some difference: divorced people reported higher para- CRANIOMANDIBULAR functional activity compared to widows and widowers who reported the least. Although awareness of PRACTICE,Copyright 2003 bruxism is not a precise measure of parafunction, based on the results we cannot support the role of by CHROMA, Inc.
stress on bruxism etiology.
Manuscript receivedJuly 8, 2002; revisedmanuscript receivedOctober 20, 2002; acceptedJanuary 28, 2003 Address for reprint requests:Dr. Marcello MelisVia Grosseto, 109125 - Cagliari,Italy Dr. Marcello Melis received his degree
Bruxism is defined by the American Academy of Orofacial Pain as a diurnal or nocturnal parafunc- in pharmacy from the University of tional activity including clenching, bracing, Cagliari (Italy) in 1990, and a D.M.D. gnashing, and grinding of the teeth.1 It is difficult to degree from the dental school of the same report the prevalence of this habit in the general popula- university in 1998. From 1998 to 2000, hewas a resident at the Gelb Orofacial Pain tion, because there are no gold standard methods to mea- Center at Tufts University, Boston, sure it. As shown in a review study performed by Seligman, Massachusetts, U.S.A. Currently, Dr. et al.,2 the prevalence depends on the way it is measured.
Melis practices in Cagliari in the field oftemporomandibular disorders and orofa- Awareness of bruxism is low, about 15%, even though it cial pain and has been involved in several varies from one study to another;2-7 however, prevalence international research activities focusing increases to 50% if we clinically evaluate the subjects on temporomandibular disorders andorofacial pain, occlusion, and muscle interpreting dental attrition. If we interpret attrition eval- uating study casts, it goes up to 91.5%, and finally usingnocturnal electromyographic (EMG) recordings we find Dr. Youssef S. Abou-Atme received his
bruxism in 100% of the population2! This illustrates how D.D.S. degree from the Université Saint difficult is to detect parafunctional activity in the popula- Joseph (Lebanon) in 1994. After finishing tion. In fact, awareness is unquestionably a measure with a residency in craniomandibular disor-ders from the Université de Nantes low reliability, yet dental attrition (evaluated either clini- (France) in 1996, he joined the Gelb Pain cally or using dental casts) is not a sign of current brux- Center at Tufts University (Boston, MA) ism, but a cumulative record of tooth wear from both were he completed a Fellowship in tem-poromandibular disorders (TMD) and functional and parafunctional activity. In addition to that, orofacial pain (1998) and received a the amount of dental attrition is also related to age and Masters Degree in oral biology. He occlusal features of the subjects8,9 and is a sign of grind- worked as a clinical and research associ-ate at the Gelb Center during the acade- ing rather than clenching of the teeth. Also, EMG record- mic year 1998-99. Dr. Abou-Atme's ings are not completely reliable, because they detect not practice in Lebanon is limited to TMD only bruxism but also other nocturnal oral muscle activi- and orofacial pain. He is also an activepain researcher at the Université Saint ties such as myoclonus, somniloquy, and tics.8,10 The etiology of bruxism is also uncertain, but the hypotheses fall into three major categories11: BRUXISM IN A SARDINIAN POPULATION
MELIS AND ABOU-ATME
1. Local/mechanical factors and masticatory muscles,47-51 even though not all the 2. Systemic/neurological factors structures are affected in the same patient, but usually one 3. Psychological factors gives up protecting the others.52 These categories are not mutually exclusive, and one or Treatment is based on protecting the masticatory the other can be true in different situations, even in the system using occlusal appliances53-58 which avoid the same subject.
damage to the teeth, periodontium, temporomandibular Within the first category great importance has been joints, and the masticatory muscles, and trying to reduce given to occlusal factors with an attempt at interpreting bruxism using stress management,59 biofeedback modali- bruxism as an automatic reaction of the body to occlusal ties,57,59,60 and, when needed, medications.59,61,62 Lately, interferences with the purpose of eliminating them by injections of botulinum toxin have been tried with some grinding. Even though there are some data suggesting that occlusion affects muscle activity leading to parafunc- The purpose of this study was to detect the prevalence tions,12-15 most of the studies seem to deny this correla- of bruxism awareness in a specimen group drawn from tion.16 In fact, occlusal adjustment failed to reduce the population of the island of Sardinia (Italy), differenti- masseter EMG nocturnal recordings in patients seeking ating diurnal bruxism from nocturnal bruxism, and ana- treatment for bruxism,17,18 and the placement of experi- lyzing correlations between bruxism and other factors: mental occlusal discrepancies did not cause an increase in age, gender, marital status, and occupation.
nocturnal parafunctional activity.19 The choice was made because these factors, especially Among the systemic and neurological factors, we can marital status and occupation may influence the psychol- report several medications that have been shown to elicit ogy of the individual, affecting in turn parafunctional bruxism, such as amphetamines,3 L-dopa,3,20 fenflu- ramine,3,2l phenothiazine,3 other neuroleptics,22 selective Additionally, diurnal and nocturnal bruxism which serotonin reuptake inhibitors (SSRls),23-27 and all anti- could be two separate issues and the result of different psychotic agents which frequently cause dyskinesias: factors, and might respond to different treatments.3,4,64,65 fluphenazine, haloperidol, loxapine, molindone, per- This is why the authors chose to evaluate these two man- phenazine, pimozide, thiothixene, trifluoperazine.28 Also ifestations of bruxism separately.
recreational drugs (heroin, cocaine, ecstasy, marijuana,"crack", LSD, methadone) have been reported to increase Materials and Methods
bruxism as well as other parafunctional oral activities.29 Some neurological pathologies may be associated with One thousand fourteen (1014) Sardinian (citizens of parafunctional oral activity. These are all disorders that the island of Sardinia, Italy, population 1,423,808 are characterized by involuntary movements such as [regional electoral lists 11/1999]) adult subjects were dyskinesias,30 Parkinson's disease,30 and other extrapyra- interviewed on their habit of clenching or grinding their midal disorders.31,32 teeth during the day and/or during the night, on their age, A lot has been written on psychological factors that are gender, marital status, and occupation.
supposed to trigger bruxism. Stress seems to be the most The following questions were in the questionnaire: significant and the most frequently mentioned in the liter- 1. Do you have the habit of clenching, grinding your ature. In some studies by Rugh, et al.,12,33 EMG nocturnal teeth, sliding them between each other or keeping monitoring showed a strong association between stressful them tight together? events (exams, family, and job problems) and muscle And in case of a positive answer: activity, and other studies had similar results.34 On the 2. During the day, during the night, or both? other hand, other studies obtained different results.6,35,36 These questions were followed by information on age, Type-A behavior has been related to bruxism evalu- gender, marital status, and occupation. No effort was ated by occlusal wear, especially if associated with higher made to verify the data or to distinguish symptomatic stress levels,38 other personality traits,39 and anxiety.37,40,41 from asymptomatic people. Several inves-tigators in dif- But again, another study by Harness, et al.42 denied any ferent social and occupational areas, but without stan- association between bruxism and psychological distur- dardized randomization, recruited the subjects.
bance as measured by the Minnesota multiphasic person-ality inventory (MMPI), agreeing with other studies.43 The effects of bruxism are indeed directed towards all the structures of the stomatognathic system, including In this study, we looked at different groups with differ- teeth,44,46 periodontium,45 temporomandibular joints,47,48 ent characteristics. RxC table (contingency table) was THE JOURNAL OF CRANIOMANDIBULAR PRACTICE APRIL 2003, VOL. 21, NO. 2 MELIS AND ABOU-ATME
BRUXISM IN A SARDINIAN POPULATION
used to calculate the chi-square statistics to investigate professional, inactive, law enforcement, light physical the null hypothesis of no association between the row and worker, manager, office worker, professional, salesper- column variables.66 Statistical significance was accepted son, and student. Statistical analysis did not show signif- for p<0.05. For significant associations, Index of differ- icant association between overall parafunction and job ence (I dif.) was calculated in order to judge and classify categories (chi-square =10.39, P>0.05). When analyzed association factors. regarding daily activity of parafunction: nocturnal, diur-nal, nocturnal/diurnal or nonparafunction, there was no significant association with any job (chi-square = 37.37,
P>0.05), as shown in Table 3, Figure 3.
Gender: 1014 subjects answered the questionnaire, Age: As mentioned earlier, the mean age was 37.23 542 being females, and 472 males (53.5% F, 46.5% M; years (SD 14.38, range 18-84). Subjects were grouped in mean age 37.23 years, SD 14.38, range 18-84). 276 sub- five age categories. Statistical analysis showed no signif- jects (27.2%) reported bruxism. The data showed no sig- icant association between overall parafunction and differ- nificant difference between males and females regarding ent age categories (chi-square = 6.65, P>0.05). When parafunctional activity (chi-square = 0.4, p>0.05).
analyzed regarding daily activity of parafunction: noctur- Diurnal/Nocturnal Bruxism: Even differentiating nal, diurnal, diurnal/nocturnal or nonparafunction and between diurnal and nocturnal parafunction data analysis age categories (Table 4 and Figure 4), no significant
did not show significant gender difference between para- associations were found (chi-square = 15.59, P>0.05).
function (either diurnal or nocturnal or diurnal/nocturnal)and nonparafunction groups (chi-square = 0.75, P>0.05).
Table 1 and Figure 1 show gender distribution of para-
function.
Based on our results, 276 subjects reported some para- Marital Status: Out of 1014 subjects, 577 were single, functional habit, which is 27.2% of the population we 396 married, 22 divorced, and 19 widows/widowers examined. Even though the data found in the literature (Table 2, Figure 2). Overall parafunctional activity
are not consistent and vary significantly probably due to between these four marital status groups showed signifi- the different populations surveyed and to different ways cant difference (chi-square = 12.38, P<0.01). Based on of evaluating bruxism, awareness seems to range from six the Index of difference (I dif.=( E-O )/O) and following a to 23%.2,8 Since the range is so wide, we can consider the decreasing order, associations between parafunction and percentage we obtained not so different, but we cannot marital status were as follows: Divorced (0.40), Widow(er) exclude some peculiarity due to differences in the exam- (0.29), Married (0.24) and Single (0.10). Even though ined population and probably to the way the questions on very close to being statistically significant, marital status the questionnaire were formulated. We also did not take failed to show any significant association (chi-square = into account the effect on bruxism of medications or neu- 16.8, P>0.05) related to nocturnal, diurnal, diurnal/noc- rological diseases, because this information was not turnal and nonparafunction groups.
included in the questionnaire. In addition to that, subjects Occupation: Subjects were grouped in eleven job in this study were selected and interviewed casually, categories: educator, hard physical worker, health care without any standardized randomization, leading to some Gender Distribution of Diurnal and Nocturnal Parafunctional Activity Parafunction and gender showed no significant association (chi-square = 0.75, P>0.05, df=3) APRIL 2003, VOL. 21, NO. 2 THE JOURNAL OF CRANIOMANDIBULAR PRACTICE


BRUXISM IN A SARDINIAN POPULATION
MELIS AND ABOU-ATME
Figure 1
Gender distribution of diurnal and nocturnal
parafunctional activity (%).
involuntary selection bias, possibly altering the results of found gender differences between diurnal and nocturnal the survey. However, the number of the subjects (1014) clenching and grinding behavior, with more men report- should be high enough to help reduce this bias.
ing diurnal bruxism and more women reporting nocturnal Comparing male to female subjects we could not bruxism. Even though our results show a slightly higher detect any significant difference in parafunctional habits.
number of females reporting nocturnal parafunction, this This result agrees with Glaros, et al.'s4 study were overall trend did not reach statistical significance, and no differ- parafunctions where equal in men and women, but they ences were found regarding diurnal and diurnal/nocturnal Marital Status Distribution Between Parafunction and Nonparafunction *Parafunction and marital status showed significant association (chi-square=12.38, P<0.01, df=3) THE JOURNAL OF CRANIOMANDIBULAR PRACTICE APRIL 2003, VOL. 21, NO. 2


MELIS AND ABOU-ATME
BRUXISM IN A SARDINIAN POPULATION
Figure 2
Marital distribution between parafunction and
nonparafunction (%).
bruxism. Another study2 reports higher bruxism scores in Among the four Marital Status groups, the Divorced males than in females, but the method they used to mea- group showed the highest parafunctional activity, while sure it was based on study cast evaluation and cannot be Married and Widow(er) showed the least. Considering a measure of awareness. That is why we cannot compare that the Divorced group included only 22 people, and the results.
Widow(er) 19, this small number compared to the othertwo groups (396 Married, 577 Single) might have given Detailed Parafunctional Distribution Per Job Hard physical worker Health care professional Light physical worker Parafunctional and jobs showed no significant association (chi-square=37.37, P>0.05, df=30) APRIL 2003, VOL. 21, NO. 2 THE JOURNAL OF CRANIOMANDIBULAR PRACTICE


BRUXISM IN A SARDINIAN POPULATION
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Figure 3
Detailed parafunctional distribution
per job (%).
us unreliable results. Conversely, divorced subjects could high competition (professional, salesperson, student) to lead a more stressful life, which may, in turn, elicit para- show higher bruxism, but we did not detect this differ- function. But here we must say that our overall results did ence, even though students and health care professionals not suggest a strong link between stress and bruxism.
seem to report more parafunctional activity.
In fact, different job categories did not seem to be asso- If we consider that job is probably one of the most ciated with different parafunctional activity, neither common sources of stress, we may conclude that, in light assessing it as a whole nor separately as diurnal and/or of the results of this study, stress has no role in causing nocturnal parafunctional activity. We could have expected bruxism, agreeing with other previous studies.36,38,43,44 categories including jobs that share high responsibility One limitation of this study is that we measured brux- (health care professional, law enforcement, manager) or ism prevalence asking the subjects if they "clench or Detailed Parafunctional Age Distribution Parafunction and age categories showed no significant association (chi-square = 15.59, P>0.05, df=12) THE JOURNAL OF CRANIOMANDIBULAR PRACTICE APRIL 2003, VOL. 21, NO. 2


MELIS AND ABOU-ATME
BRUXISM IN A SARDINIAN POPULATION
Figure 4
Detailed parafunctional age (years)
distribution (%).
grind their teeth" and bruxism awareness does not coin- cide with actual bruxing activity; we could have subjectswho have such a parafunctional habit in spite of them The authors would like to acknowledge Dr. Simona being unaware of it. This limitation probably led to some Foddis, Dr. Alessandro Piras, and Paolo Putzolu for their bias and might have hidden a possible link between the great help collecting the data.
variables we examined. Furthermore, we arbitrarilygrouped the jobs into categories within which subcate- gories might not be uniformly stressful.
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