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Therapies most frequently used for the management of bruxism by a sample of German dentists
Therapies most frequently used for the management of bruxism by a sample of German dentists Michelle A. Ommerborn, PhD, Dr med dent,a Jalleh Taghavi,b Preeti Singh, DDS, MScD,c Joerg Handschel, PhD, MD, Dr med dent,d Rita A. Depprich, PhD, MD, Dr med dent,e and Wolfgang H. M. Raab, PhD, Dr med dentf Heinrich-Heine-University, Duesseldorf, Germany; Duesseldorf University Hospital, Duesseldorf, Germany Statement of problem. At present, there is little information available on how practicing dentists manage bruxism patients with respect to conservative, reversible techniques as compared to irreversible techniques. Purpose. The purpose of this study was to determine the most commonly applied therapies used for the management of bruxism by German general dentists (GDs) and dental specialists. In addition, efforts were made to gather information on the knowledge and opinion of GDs and specialists regarding the role of occlusal interferences, in particular, on the development of sleep bruxism. Material and methods. A 13-item questionnaire was developed and mailed to all active members of the statutory dental insurance providers of the German North Rhine (n=5500; 2006 roster) and the German Westphalia-Lippe area (n=4984; 2006 roster). Group differences were statistically analyzed using chi-square tests for the qualitative variables and Mann-Whitney U tests for the quantitative variables (α=.05). Results. Occlusal splints were by far the most frequently prescribed therapy for the management of bruxism, followed by relaxation techniques, occlusal equilibration, physiotherapy, and prosthodontic reconstruction. The occlusal stabilization splint with canine protected articulation was the splint type most often prescribed, whereas respondents used unadjusted soft splints for approximately 8% of their bruxism patients. Comparison of the opinions of all responding practicing dentists with that of experts in regard to the statement that “sleep bruxism is caused by occlusal interferences” showed a significant difference between the 2 groups (P=.021). Eighty-five percent of the experts disagreed with this statement, and only 47.7% of the practicing dentists had the same opinion as the experts. Conclusions. Most practicing dentists seem to concur with current scientific recommendations, and express the opinion that the management of bruxism should predominantly be conservative and reversible; however, the findings of the present survey reveal diverse differences between GDs and dental specialists concerning the most frequently prescribed therapies. Moreover, the discrepancies detected in some areas, such as the use of irreversible techniques or the use of unadjusted soft splints, emphasize the need to more promptly transfer new knowledge in the field of bruxism from researchers to practicing dentists. (J Prosthet Dent 2011;105:194-202)
Clinical Implications
The present results indicate that there is a need to more promptly disseminate new insights in the field of bruxism. For this reason, it seems that predoctoral dental training in bruxism should be strengthened and that the topic of bruxism should be expanded in postdoctoral courses. Associate Professor, Department of Operative Dentistry, Periodontology and Endodontics, Heinrich-Heine-University. Postgraduate student, Department of Operative Dentistry, Periodontology and Endodontics, Heinrich-Heine-University. c Assistant Professor, Department of Operative Dentistry, Periodontology and Endodontics, Heinrich-Heine-University. d Associate Professor, Department of Cranio- and Maxillofacial Surgery, Heinrich-Heine-University. e Associate Professor, Department of Cranio- and Maxillofacial Surgery, Heinrich-Heine-University. f Professor, Department of Operative Dentistry, Periodontology and Endodontics, Heinrich-Heine-University; CEO, Duesseldorf University Hospital. a
b
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March 2011 Bruxism is defined as a diurnal or nocturnal parafunctional activity, which comprises clenching, bracing, gnashing, and grinding of the teeth.1-3 Although the etiology of bruxism has not been clarified, among researchers in the field of bruxism, there is a consensus on its multifactorial nature.4 In early scientific research on the subject, peripheral factors, particularly, occlusal interferences, were regarded as essential for the onset of bruxism.5 Accordingly, the management of bruxism consisted primarily in occlusal strategies, such as irreversible occlusal interventions6-10 or the use of occlusal splints.11-14 However, in the past 15 years, corresponding with the methodological improvement of clinical investigations,15,16 research has principally been focused on central factors (such as neuropathophysiology and psychology),17-27 and has provided new insights into the etiology of bruxism. As a result, peripheral factors are currently relegated to only a minor role, and this has resulted in an alteration in the therapy recommendations for bruxism.4,28 Currently, there is a considerable consensus among bruxism researchers that the management of most situations should be conservative and reversible.4,29-31 Furthermore, conflicting results on the clinical efficacy and effectiveness of occlusal splints, and the lack of knowledge regarding the potential underlying mechanisms that explain their apparent success in the management of bruxism, have led to the view that occlusal splints are merely a nonspecific therapy for bruxism.32 Based on this, reviews suggest that the use of occlusal splints be restricted to the prevention and/ or limitation of dental damage that is potentially induced by the disorder.4,32 Therefore, it is of interest as to what extent these insights and the resulting scientific recommendations have reached practicing dentists and, moreover, how general dentists (GDs) view bruxism. To date, there have been only a few studies that evaluate the transfer of knowledge from research-
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ers to front-line care providers. These investigations essentially focused on the prescription patterns for occlusal splints.33,34 In 1995, a random sample of US dentists was surveyed to determine the type of occlusal splint most preferred, and the number of splints that were fabricated over the preceding year for bruxism patients. Results indicated that both GDs and dental specialists had made approximately 11 splints in the preceding year. Of the 380 dentists who had made splints for bruxism patients, 14.5% fabricated occlusal splints from only soft materials, 59.4% made only hard acrylic resin splints, and 26.1% varied with respect to their selection of materials.34 Similarly, the outcome of a recent retrospective study in Sweden revealed that the most common indication for the use of hard acrylic resin stabilization splints, as well as for soft splints, was occlusal wear due to bruxism.33 Although several investigations have shown increased electromyographic (EMG) activity in patients wearing soft splints,12,35 the results of the 2 previously mentioned studies show discrepancies between scientific knowledge and the opinion and decisions of practicing dentists in regard to the use and, in particular, the type of occlusal splints prescribed for the management of bruxism.33,34 At present, there is little information available on how German GDs manage bruxism patients using both conservative reversible and irreversible techniques. Likewise, there is little information on the percentage of bruxism patients in German dental practices. Therefore, the purpose of this investigation was to determine the most frequently applied therapies and, in particular, the prescription patterns for occlusal splints used by German GDs and dental specialists for the management of bruxism. Furthermore, the authors made an effort to gather information on the knowledge and opinions of GDs and specialists regarding the role of occlusal interferences, in particular, the development of sleep bruxism. The first
null hypothesis of this study was that there would be no difference among GDs and dental specialists with respect to the most frequently applied therapies; the second null hypothesis was that GDs and dental specialists would not differ regarding the scientific recommendations for the management of bruxism.
MATERIAL AND METHODS A 13-item questionnaire was developed to identify the therapies prescribed most frequently and, particularly, the prescription patterns for occlusal splints used by German GDs and dental specialists for the management of patients diagnosed with bruxism. The questionnaire was mailed along with a cover letter, explaining the purpose of the survey and requesting participation. A stamped, self-addressed envelope was enclosed with the questionnaire and mailed to all active members of the statutory dental insurance providers of the German North Rhine (n=5500; 2006 roster) and the German WestphaliaLippe area (n=4984; 2006 roster). To ensure the anonymity of the respondents, the questionnaires were mailed by the statutory dental insurance providers along with their regular quarterly newsletter. No financial incentive was provided for responding to the survey. The first 5 questions in the questionnaire gathered sociodemographic and descriptive information on the respondents. In addition, respondents were asked to estimate the percentage of patients that were diagnosed with bruxism in their own practices in the past year and the percentage of those patients needing therapy and receiving it. The definition of bruxism was clearly stated as “the involuntary grinding and clenching of the teeth” at the bottom of the first page. The definition was limited not only to keep the questionnaire simple, but also to consider the fact that the present management strategies in many German dental practices differenti-
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Volume 105 Issue 3 ate little between diurnal and sleep bruxism. Respondents were explicitly informed not to include patients diagnosed with craniomandibular disorders. The last question in the first section was to identify whether respondents primarily referred their bruxism patients to other clinicians or to university-based care centers. Respondents who treated bruxism patients themselves were asked to continue the questionnaire. The next 4 questions in the questionnaire requested that respondents specify the percentage of the various therapeutic modalities used, the types and distribution of occlusal splints, and the number of occlusal splints made for the management of bruxism patients. The respondents were further asked to provide details regarding the wear time they most frequently recommended for each type of occlusal splint. With the intention of gaining information on the knowledge and opinions of practicing dentists, in particular, regarding sleep bruxism, the last part of the questionnaire included one statement, “Sleep bruxism is caused by occlusal interferences,” which was derived from a mail survey designed at the University of Wash-
ington and fielded in the Seattle36 and the Kansas City areas.37 Due to the complexity of the questionnaire used in the current study, only one statement relating to the topic of sleep bruxism was taken from the 4 original categories in the University of Washington survey. This statement was derived from the psychophysiological category, which included questions related to the interaction of physical and psychological factors in temporomandibular disorders (TMDs) etiology, diagnosis, and management. Respondents were asked to rate their answer according to an 11-point scale in which 0 represented “strongly disagree,” 10 represented “strongly agree,” and 5 represented a “neutral’” standpoint. In the original Seattle study,36 statements were verified by 2 panels of experts who formed the expert group. As in the Kansas City survey,37 the expert responses used in the Seattle study were also used in the present investigation. A statement was defined as “expert consensus” if more than 75% of the experts in the designated group endorsed either an “agree” (scores 7-10) or a “disagree” response (scores 0-3). Statistical analysis was performed
using statistical software (SPSS, v. 17.0; SPSS, Inc, Chicago, Ill). Normal distribution was tested using the Kolmogorov-Smirnov test along with an assessment of histograms. The Pearson chi-square test was used to determine the significance of differences between 2 independent groups when data consisted of frequencies in discrete categories. For all quantitative variables that were not normally distributed, differences were evaluated by means of the nonparametric Mann-Whitney U test. For all statistical analyses, an alpha error probability of .05 was defined as the statistically significant level.
RESULTS In total, 939 (8.96%) of the 10,484 questionnaires mailed were returned. Six hundred and eighty (72.4%) respondents provided complete data, 12 (1.3%) had filled in only the first section of the questionnaire, and in 247 (26.3%) resubmitted questionnaires, at least one item of the questionnaire was not completed. The largest proportion of responding participants (368 (39.9%) of 922) had 11 to 20 years of professional work experience. Approximately 52% (489)
Table I. Demographic and practice characteristics of respondents Dental Specialists
General Dentists
P
17.75 ± 8.61
18.33 ± 8.77
.516a
Male (n=935)
95 (75.4%)
603 (74.5%)
.836b,c
Age (n=929)
45.57 ± 8.82
45.95 ± 8.55
.514a
Percentage of patients diagnosed with bruxism (n=923)
13.84 ± 14.86
15.79 ± 16.55
.175a
Percentage of bruxism patients needing therapy and receiving it (n=922)
27.86 ± 33.52
32.53 ± 33.27
.020a
Number of years in professional practice (n=922)
.001b
Do you predominantly treat bruxism patients on your own? (n=931) Yes
100 (79.4%)
737 (91.6%)
No
26 (20.6%)
68 (8.4%)
aMann-Whitney U test; data are presented as mean ± standard deviation (SD). bChi-square test cOne respondent failed to report his/her gender.
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March 2011 of the returned questionnaires were from members of the statutory dental insurance providers of the German North Rhine, and 47.6% (444) were practitioners in the Westphalia-Lippe area. Significantly more male than female dentists returned the questionnaire, 74.2% (699) versus 25.4% (239) (chi-square test, P=.004). This respondent distribution is consistent with the approximate gender distribution of practicing dentists in both statutory dental insurance provider groups (30.0% female in the German North Rhine area and 29.0% female in the Westphalia-Lippe area) and is thus representative of the population of dentists in the former West German federal states. Some of the demographic and descriptive characteristics of the respondents, classified as dental specialists and GDs, are shown in Table I. One hundred and twenty-eight (13.6%) of the respondents were dental specialists, and 811 (86.4%) were GDs. Forty-three orthodontists represented the largest proportion of specialists (33.6%), followed by 24 dentists with
postgraduate qualifications in oral implantology (18.8%) and 19 oral surgeons (14.8%). Further specialist groups included 13 oral and maxillofacial surgeons (10.2%), 9 periodontists (7%), 3 prosthodontists (2.3%), 2 endodontists (1.6%), 2 specialists in preventive and restorative dentistry (1.6%), 1 pediatric dentist (0.8%), and 12 others (9.4%). Table II shows the average percentage of patients for whom respondents reported prescribing one of the 10 most common therapies for the management of bruxism. Occlusal splints were by far the most frequently prescribed, followed by relaxation techniques, occlusal equilibration, physiotherapy, and prosthodontic reconstruction. In the preceding year, a GD made an average of 27.5 occlusal splints (SD, 31.85; range, 0 to 300) while a dental specialist made an average of 19.8 occlusal splints (SD, 37.37; range, 0 to 300) (Mann-Whitney U test, P<.001). The number of occlusal splints made in the preceding year, divided into 6 categories (0 occlusal splints, or 1-10, 11-50, 51-100,
101-200, or 201-300) revealed a statistically significant group difference (chi-square test, P<.001). As seen in Figure 1, the majority of respondents in both groups fabricated 50 or fewer occlusal splints in the preceding year. With respect to prescription patterns for the different splint types, Table III provides the average percentage of patients treated by GDs and dental specialists with different types of occlusal splints. The most frequently used splint type was the occlusal stabilization splint with canine protected articulation, followed by the occlusal splint with group function and the unadjusted hard splint. Table IV shows, for the respective type of occlusal splint, the percentage of respondents who recommended splint use for 24 hours, only at night, if required, or various combinations of usage times. As seen from Table IV, there is considerable agreement between GDs and dental specialists as to the prescribed usage times. For all types of occlusal splints, the most frequently recommended use was at night. With respect to the opinions of
Table II. Average percentage of patients treated with the most frequent therapies for bruxism Patients of Dental Specialists
Patients of General Dentists
P
Occlusal splints (n=909: 120 dental specialists and 789 GDs)
52.37%
73.11%
.001
Relaxation techniques (n=914: 120 dental specialists and 794 GDs)
17.19%
14.51%
.880
Occlusal equilibration (n=914: 120 dental specialists and 794 GDs)
7.23%
9.20%
.003
Physiotherapy (n=918: 120 dental specialists and 798 GDs)
8.35%
6.70%
.579
Prosthodontic reconstruction (n=911: 120 dental specialists and 791 GDs)
4.03%
5.59%
.004
Orthodontics (n=917: 120 dental specialists and 797 GDs)
7.28%
0.65%
.001
Psychotherapy (n=918: 121 dental specialists and 797 GDs)
2.99%
2.32%
.847
Thermal packs (n=918: 121 dental specialists and 797 GDs)
1.97%
1.34%
.617
Medications (n=919: 121 dental specialists and 798 GDs)
1.33%
1.10%
.411
Diet counseling (n=918: 121 dental specialists and 797 GDs)
0.50%
1.71%
.264
Miscellaneous (n=915: 122 dental specialists and 793 GDs)
4.02%
2.48%
.311
Therapy
Mann-Whitney U test was used to assess differences between dental specialists and GDs.
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Volume 105 Issue 3
Number of Responding Practicing Dentists
500 Dental specialists
416
400
GDs
300 215
200 100 0
43 48
0
31
1-10
33
11-50
58 10
2
18
1
1
51-100 101-200 201-300
Number of Occlusal Splints 1 Number of occlusal splints made by responding dentists in preceding year is shown following classification into 6 groups. Majority of both groups fabricated 50 or fewer occlusal splints in preceding year.
Table III. Average percentage of patients treated with various occlusal splint types Patients of Dental Specialists
Patients of General Dentists
P
Stabilization splint with canine protected articulation (n=910: 120 dental specialists and 789 GDs)
32.98%
42.49%
.018
Occlusal splint with group function (n=913: 122 dental specialists and 791 GDs)
10.06%
16.54%
.001
Unadjusted hard splint (n=913: 122 dental specialists and 791 GDs)
8.63%
16.45%
.009
Unadjusted soft splint (n=916: 122 dental specialists and 794 GDs)
7.28%
8.23%
.719
Repositioning splint (n=914: 122 dental specialists and 792 GDs)
5.22%
3.34%
.517
Reflex splint with anterior ramp (n=915: 122 dental specialists and 793 GDs)
1.20%
1.80%
.269
Type of Occlusal Splint
Mann-Whitney U test was used to assess differences between dental specialists and GDs.
practicing dentists pertaining to the etiology of sleep bruxism, the initial analysis revealed no statistically significant differences between the responses of GDs (47.0% disagree) and dental specialists (52.1% disagree) compared to the expert opinions (chisquare test, P=.513). For this reason, the opinions of both the responding GDs and the responding specialists were combined and their responses compared to the experts’ opinion. As shown in Figure 2, 85% of the experts
disagreed with the statement that “sleep bruxism is caused by occlusal interferences,” and only 47.7% of the practicing dentists had the same opinion as the experts. This difference between the experts and the responding practicing dentists was statistically significant (chi-square test, P=.021). Apart from this disagreement between the practicing dentists and the experts, 28.6% of the practicing dentists had a neutral opinion and thus expressed their uncertainty
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about the statement. To compare the present opinion of German practicing dentists with results derived from a preceding survey, the responses of the practicing dentists received in the Kansas City study37 are also shown in Figure 2. As derived from this comparison, the disagreement of the practicing dentists surveyed in the current study was approximately 15% greater than the disagreement of practicing dentists questioned 20 years ago in the Kansas City area.
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March 2011
Table IV. Number (%) of respondents who recommend various application durations for different occlusal splint types Dental Specialists (%) Type of Occlusal Splint Stabilization splint with canine protected articulation
At Night
24 h
If Required
General Dentists (%)
Diverse Combinations
At Night
24 h
If Required
Diverse Combinations
P .506
5
33
5
7
34
341
21
44
(10.0)
(66.0)
(10.0)
(14.0)
(7.7)
(77.5)
(4.8)
(10.0)
(n=490: 50 dental specialists and 440 GDs) Occlusal splint with group function
2
11
1
4
20
176
15
21
(11.1)
(61.1)
(5.6)
(22.3)
(8.6)
(75.9)
(6.5)
(9.0)
.628
(n=250: 18 dental specialists and 232 GDs) Unadjusted hard splint (n=267: 25 dental specialists
1
20
3
1
11
193
20
18
(4.0)
(80.0)
(12.0)
(4.0)
(4.5)
(79.8)
(8.3)
(7.4)
.934
and 242 GDs) Repositioning splint (n=106: 12 dental specialists
5
5
0
2
27
55
7
5
(41.7)
(41.7)
(0)
(16.7)
(28.7)
(58.5)
(7.4)
(5.3)
.079
and 94 GDs) Unadjusted soft splint (n=180: 19 dental specialists
1
6
2
0
12
114
25
10
(5.3)
(84.2)
(10.5)
(0)
(7.5)
(70.8)
(15.5)
(6.2)
.736
and 161 GDs) Reflex splint with anterior ramp
1
3
2
0
7
42
9
6
(16.7)
(50.0)
(33.3)
(0)
(10.9)
(65.6)
(14.1)
(9.4)
(n=70: 6 dental specialists and 64 GDs) Chi-square test was used to determine significance of differences between dental specialists and GDs.
Percent of Disagree
100 80
P=.021 85.0%
Statement: “Sleep bruxism is caused by occlusal interferences” (n=915)
60 47.7%
40
33.0%
20 0
Expert Response (Le Resche et al.36)
Responding Dentists (Present Survey)
Practicing Dentists (Glaros et al.37)
Surveys 2 Percentage of responding dentists agreeing with expert response regarding statement on sleep bruxism. To compare present opinion of German practicing dentists with results derived from preceding survey, responses of practicing dentists received in Kansas City study are also shown.
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.694
200
Volume 105 Issue 3 DISCUSSION
The purpose of the present study was to evaluate whether GDs and dental specialists differ with respect to their most frequently applied therapies for the management of bruxism. The results of this study indicate that in 4 of the 10 most frequently prescribed therapies, GDs and dental specialists differed to a statistically significant extent. Moreover, significant discrepancies between the 2 groups were found in the average number of occlusal splints made in the preceding year and the type of occlusal splints that were prescribed. Therefore, the null hypothesis that there is no difference among GDs and dental specialists with respect to the most frequently applied therapies was rejected. A second objective of the present study was to identify whether the surveyed GDs and dental specialists differ regarding the scientific recommendations for the management of bruxism. The findings of this investigation confirm agreement of practicing dentists with the current scientific recommendations; most respondents indicated that the management of bruxism should predominantly be conservative and reversible.4,29-31 For both GDs and dental specialists, occlusal splints were the first-choice treatment, followed by relaxation techniques. However, apart from these reversible techniques, an appreciable number of practicing dentists still use irreversible techniques, such as occlusal adjustment, prosthodontic restoration, or orthodontics, for the management of bruxism. For example, GDs were found to manage approximately 9% of their bruxism patients with occlusal equilibration. A potential explanation for this finding might be that this irreversible technique is recommended by a few authors,6-8 although their suggestions are predominantly based on opinions and subjective clinical experiences and less on well-founded scientific data. However, considering that, on average, rsponding practicing dentists graduated 18 years prior
to this study, and given that substantial changes in the field occurred during this period, these findings may indicate a delayed transfer of knowledge from researchers to front-line care providers. Extending the topic of bruxism in postdoctoral courses will promote transfer of knowledge and thus will support clinicians in their daily decision-making process. Most importantly, there is a need to discover the definitive underlying etiology of bruxism and, accordingly, the causeoriented management approaches. Based on available literature on bruxism, occlusion is known to have only a minor role in the development of bruxism,23 if any.4,23,29,31 Moreover, as shown by various review articles, there is no high-quality, evidencebased support for the use of irreversible techniques.4,9,10,29,31 Therefore, the null hypothesis that both GDs and dental specialists do not differ from scientific recommendations regarding the management of bruxism is rejected. With regard to the type of occlusal splint prescribed by practicing dentists, the responses of the present survey are largely consistent with the current view of scientific dental experts. While various authors have reported on the efficacy of occlusal stabilization splints, the clinical results obtained were not found to be superior to those obtained for other types of splints.13,14 There is, however, one exception: the use of soft splints. The present investigation revealed that on average, 8% of the practicing dentists prescribe unadjusted soft splints for the management of their bruxism patients, even though the data of 2 studies indicate that soft splint material may actually increase bruxism activity in some patients.12,35 Although hard splints are suggested to be more effective in reducing bruxism activity,11,12 it appears that the traditional decision-making process of dentists in this study, which is similar to that of Swedish dentists,33,38 is based on knowledge gained through individual past experience, practice traditions,
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and the opinions of recognized authorities. Given the conflicting results on the clinical efficacy and effectiveness of occlusal splints and the lack of knowledge regarding the potentially underlying mechanisms that explain their apparent success in the management of bruxism, it is reasonable to view the occlusal splint primarily as a nonspecific therapy for bruxism. Therefore, reviews suggest that the use of occlusal splints be limited to the prevention and/or limitation of dental damage potentially induced by the disorder.4,29,32 To gain information on dentists’ belief regarding the role of occlusal interferences on the development of sleep bruxism, the survey used in the current study included one statement derived from a mailed survey that was designed at the University of Washington and fielded in the Seattle area.36 Although the statement was developed in 1993, its validity was verified by a panel of experts in 200738 and in various scientific publications.4,19,20,22,23,31,32,39 In the present study, no difference in opinion was found between the GDs and dental specialists; however, there was a considerable discrepancy between the responding practicing dentists and the experts. Furthermore, it should be noted that, on average, 30% of the practicing dentists had a neutral opinion. This finding could be interpreted as tacit uncertainty instead of open disagreement with the expert opinion. The uncertainty might stem from a lack of information or from knowledge of arguments on both sides of the issue and, consequently, an ambiguous opinion. As has been previously discussed, the finding with respect to this statement also points to a discrepancy between what is known by scientific researchers in the area of bruxism and what is believed by practicing dentists. The present investigation includes some shortcomings that must be considered when data are interpreted. First, within this survey, some percentages did not add up to 100 per-
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March 2011 cent. This arises from the effect of rounding and the fact that some respondents failed to answer all of the questions on the survey. Secondly, the response rate in the present study, when compared to that of a previous survey performed in the US, appeared relatively low and, therefore, a response bias might have influenced the outcome of this investigation. Nevertheless, the lack of gender differences between GDs and dental specialists and the close approximation of the respondents’ gender distribution to that of the original study sample and the former West German federal states dentist population corroborate the validity of the data. Accordingly, data obtained from the responding practicing dentists can be regarded as representative. The low response rate could be attributed to the complexity of the survey, as the questionnaire consisted of 3 sections that dealt with diverse issues. Another possible explanation might be that, compared to dentists in the US, German dentists are, in general, less trained and less familiar with surveys. In addition, this was the first survey on the topic of bruxism. Apart from that, in the US, there appears to be a general interest in data collection and, consequently, the willingness to participate in a survey is stronger than it is in Germany. Moreover, in contrast to previous surveys of dentists in the US, this investigation was performed anonymously (as is usual in diverse German surveys) and, therefore, there was neither a chance to remind nonrespondents via telephone, nor did the participants receive any financial incentive to participate.
CONCLUSIONS Practicing dentists seem to concur with current scientific recommendations, expressing the opinion that the management of bruxism should predominantly be conservative and reversible. However, the findings reveal diverse differences between GDs and dental specialists concerning the
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most frequently prescribed therapies, the average number of occlusal splints made in the preceding year, and the type of occlusal splints used. Moreover, the discrepancies detected in some areas, such as the use of irreversible techniques or the use of soft splints, emphasize the need to more quickly transfer new knowledge in the field of bruxism from researchers to practicing dentists.
REFERENCES 1. American Academy of Sleep Medicine. The international classification of sleep disorders, revised: diagnostic and coding manual. 2nd ed. Westchester: American Academy of Sleep Medicine; 2005. p. 189-92. 2. American Academy of Orofacial Pain. Orofacial pain: guidelines for assessment, diagnosis and management. In: de Leeuw R, editor. 4 th ed. Chicago: Quintessence; 2008. p. 257-300. 3. The glossary of prosthodontic terms. J Prosthet Dent 2005;94:19. 4. Lobbezoo F, van der Zaag J, van Selms MK, Hamburger HL, Naeije M. Principles for the management of bruxism. J Oral Rehabil 2008;35:509-23. 5. Ramfjord SP. Bruxism, a clinical and electromyographic study. J Am Dent Assoc 1961;62:21-44. 6. Ash MM Jr. Occlusion, TMDs, and dental education. Head Face Med 2007;3:1. 7. Christensen GJ. Treating bruxism and clenching. J Am Dent Assoc 2000;131:233-5. 8. Christensen GJ. The major part of dentistry you may be neglecting. J Am Dent Assoc 2005;136:497-9. 9. Clark GT, Tsukiyama Y, Baba K, Watanabe T. Sixty-eight years of experimental occlusal interference studies: what have we learned? J Prosthet Dent 1999;82:704-13. 10.Tsukiyama Y, Baba K, Clark GT. An evidence-based assessment of occlusal adjustment as a treatment for temporomandibular disorders. J Prosthet Dent 2001;86:57-66. 11.al-Quran FA, Lyons MF. The immediate effect of hard and soft splints on the EMG activity of the masseter and temporalis muscles. J Oral Rehabil 1999;26:559-63. 12.Okeson JP. The effects of hard and soft occlusal splints on nocturnal bruxism. J Am Dent Assoc 1987;114:788-91. 13.Rugh JD, Graham GS, Smith JC, Ohrbach RK. Effects of canine versus molar occlusal splint guidance on nocturnal bruxism and craniomandibular symptomatology. J Craniomandib Disord 1989;3:203-10. 14.Türp JC, Komine F, Hugger A. Efficacy of stabilization splints for the management of patients with masticatory muscle pain: a qualitative systematic review. Clin Oral Investig 2004;8:179-95.
15.Ommerborn MA, Giraki M, Schneider C, Schäfer R, Gotter A, Franz M, et al. A new analyzing method for quantification of abrasion on the Bruxcore device for sleep bruxism diagnosis. J Orofac Pain 2005;19:232-8. 16.Yoshimi H, Sasaguri K, Tamaki K, Sato S. Identification of the occurrence and pattern of masseter muscle activities during sleep using EMG and accelerometer systems. Head Face Med 2009;5:7. 17.Ahlberg J, Rantala M, Savolainen A, Suvinen T, Nissinen M, Sarna S, et al. Reported bruxism and stress experience. Community Dent Oral Epidemiol 2002;30:405-8. 18.Kampe T, Edman G, Bader G, Tagdae T, Karlsson S. Personality traits in a group of subjects with long-standing bruxing behaviour. J Oral Rehabil 1997;24:588-93. 19.Kato T, Thie NM, Huynh N, Miyawaki S, Lavigne GJ. Topical review: sleep bruxism and the role of peripheral sensory influences. J Orofac Pain 2003;17:191-213. 20.Lavigne GJ, Kato T, Kolta A, Sessle BJ. Neurobiological mechanisms involved in sleep bruxism. Crit Rev Oral Biol Med 2003;14:30-46. 21.Lobbezoo F, Lavigne GJ, Tanguay R, Montplaisir JY. The effect of catecholamine precursor L-dopa on sleep bruxism: a controlled clinical trial. Mov Disord 1997;12:73-8. 22.Lobbezoo F, Naeije M. Bruxism is mainly regulated centrally, not peripherally. J Oral Rehabil 2001;28:1085-91. 23.Lobbezoo F, Rompre PH, Soucy JP, Iafrancesco C, Turkewicz J, Montplaisir JY, et al. Lack of associations between occlusal and cephalometric measures, side imbalance in striatal D2 receptor binding, and sleeprelated oromotor activities. J Orofac Pain 2001;15:64-71. 24.Macaluso GM, Guerra P, Di Giovanni G, Boselli M, Parrino L, Terzano MG. Sleep bruxism is a disorder related to periodic arousals during sleep. J Dent Res 1998;77:565-73. 25.Ohayon MM, Li KK, Guilleminault C. Risk factors for sleep bruxism in the general population. Chest 2001;119:53-61. 26.Ommerborn MA, Schneider C, Giraki M, Schafer R, Handschel J, Franz M, et al. Effects of an occlusal splint compared with cognitive-behavioral treatment on sleep bruxism activity. Eur J Oral Sci 2007;115:7-14. 27.Schneider C, Schaefer R, Ommerborn MA, Giraki M, Goertz A, Raab WH, et al. Maladaptive coping strategies in patients with bruxism compared to non-bruxing controls. Int J Behav Med 2007;14:257-61. 28.Ommerborn MA, Schneider C, Giraki M, Schafer R, Singh P, Franz M, et al. In vivo evaluation of noncarious cervical lesions in sleep bruxism subjects. J Prosthet Dent 2007;98:150-8. 29.Attanasio R. An overview of bruxism and its management. Dent Clin North Am 1997;41:229-41. 30.Greene CS, Klasser GD, Epstein JB. ‚Observations‘ questioned. J Am Dent Assoc 2005;136:856, 858; author reply 858.
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Volume 105 Issue 3 31.Lavigne GJ, Khoury S, Abe S, Yamaguchi T, Raphael K. Bruxism physiology and pathology: an overview for clinicians. J Oral Rehabil 2008;35:476-94. 32.Dao T T, Lavigne GJ. Oral splints: the crutches for temporomandibular disorders and bruxism? Crit Rev Oral Biol Med 1998;9:345-61. 33. Lindfors E, Magnusson T, Tegelberg A. Interocclusal appliances--indications and clinical routines in general dental practice in Sweden. Swed Dent J 2006;30:123-34. 34.Pierce CJ, Weyant RJ, Block HM, Nemir DC. Dental splint prescription patterns: a survey. J Am Dent Assoc 1995;126:248-54. 35.Harkins S, Marteney JL, Cueva O, Cueva L. Application of soft occlusal splints in patients suffering from clicking temporomandibular joints. Cranio 1988;6:71-6.
36.Le Resche L, Truelove EL, Dworkin SF. Temporomandibular disorders: a survey of dentists‘ knowledge and beliefs. J Am Dent Assoc 1993;124:90-4, 97-106. 37.Glaros AG, Glass EG, McLaughlin L. Knowledge and beliefs of dentists regarding temporomandibular disorders and chronic pain. J Orofac Pain 1994;8:216-22. 38.Tegelberg A, Wenneberg B, List T. General practice dentists’ knowledge of temporomandibular disorders in children and adolescents. Eur J Dent Educ 2007;11:216-21. 39.Lavigne GJ, Manzini C, Kato T. Sleep bruxism. In: Kryger MH, Roth T, Dement WC, editors. Principles and practice of sleep medicine. 4 th ed. Philadelphia: Elsevier/ Saunders; 2005. p. 946-59.
Corresponding author: Dr Michelle A. Ommerborn Department of Operative Dentistry, Periodontology and Endodontics Heinrich-Heine-University Moorenstr. 5 40225 Düsseldorf GERMANY Fax: +49 211 81 04021 E-mail: [email protected] Acknowledgments The authors thank the statutory dental insurance providers of the German North Rhine area and the German Westphalia-Lippe area for their kind support in sending out the questionnaires. Copyright © 2011 by the Editorial Council for The Journal of Prosthetic Dentistry.
Noteworthy Abstracts of the Current Literature A 15-year clinical comparative study of the cumulative survival rate of cast metal core and resin core restorations luted with adhesive resin cement Hikasa T, Matsuka Y, Mine A, Minakuchi H, Hara ES, Van Meerbeek B, Yatani H, Kuboki T. Int J Prosthodont. 2010 Sep-Oct;23(5):397-405. Purpose. The aim of this study was to compare the core survival rates (CSRs) of cast metal versus resin core restorations luted with adhesive resin cement, as well as to determine the risk factors for core failure. Materials and Methods. Nine hundred ninety-one patients (2,124 cores) who received either cast metal or resin cores luted with adhesive resin cement at the Fixed Prosthodontic Clinic of Okayama University Dental Hospital between April 1988 and December 1991 and whose structured clinical core record was filled appropriately comprised the study subjects. The clinical core record included information regarding patient age, sex, core restoration type, tooth location, tooth type, remaining coronal dentin, and root canal form. CSRs, as well as causes for failure, were analyzed 15 years postinsertion. Since 381 patients lacked data regarding predictors for core failure, a subsample of 610 patients (1,053 cores) was used for the subsequent risk factor analysis. Results. The cumulative CSR of resin cores (78.7%) was significantly higher than that of cast metal cores (55.4%; log-rank test, P < .0001). The Cox proportional hazards test revealed that sex (male, P < .0001), absence of remaining coronal dentin (P = .0057), core restoration type (cast metal, P = .0186), and higher age at core insertion (P = .0380) were significant predictors for core failure. The incidence of complications, such as core loosening (P = .0016) and tooth extraction (P < .0001), was significantly higher in cast metal cores. Conclusions. Cast metal cores were associated with a significantly lower CSR than resin cores, and significant risk factors for core failure were sex (male), absence of remaining coronal dentin, core restoration type (cast metal), and higher age at core insertion. Reprinted with permission of Quintessence Publishing.
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Clinical Implications
The present results indicate that there is a need to more promptly disseminate new insights in the field of bruxism. For this reason, it seems that predoctoral dental training in bruxism should be strengthened and that the topic of bruxism should be expanded in postdoctoral courses. Associate Professor, Department of Operative Dentistry, Periodontology and Endodontics, Heinrich-Heine-University. Postgraduate student, Department of Operative Dentistry, Periodontology and Endodontics, Heinrich-Heine-University. c Assistant Professor, Department of Operative Dentistry, Periodontology and Endodontics, Heinrich-Heine-University. d Associate Professor, Department of Cranio- and Maxillofacial Surgery, Heinrich-Heine-University. e Associate Professor, Department of Cranio- and Maxillofacial Surgery, Heinrich-Heine-University. f Professor, Department of Operative Dentistry, Periodontology and Endodontics, Heinrich-Heine-University; CEO, Duesseldorf University Hospital. a
b
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March 2011 Bruxism is defined as a diurnal or nocturnal parafunctional activity, which comprises clenching, bracing, gnashing, and grinding of the teeth.1-3 Although the etiology of bruxism has not been clarified, among researchers in the field of bruxism, there is a consensus on its multifactorial nature.4 In early scientific research on the subject, peripheral factors, particularly, occlusal interferences, were regarded as essential for the onset of bruxism.5 Accordingly, the management of bruxism consisted primarily in occlusal strategies, such as irreversible occlusal interventions6-10 or the use of occlusal splints.11-14 However, in the past 15 years, corresponding with the methodological improvement of clinical investigations,15,16 research has principally been focused on central factors (such as neuropathophysiology and psychology),17-27 and has provided new insights into the etiology of bruxism. As a result, peripheral factors are currently relegated to only a minor role, and this has resulted in an alteration in the therapy recommendations for bruxism.4,28 Currently, there is a considerable consensus among bruxism researchers that the management of most situations should be conservative and reversible.4,29-31 Furthermore, conflicting results on the clinical efficacy and effectiveness of occlusal splints, and the lack of knowledge regarding the potential underlying mechanisms that explain their apparent success in the management of bruxism, have led to the view that occlusal splints are merely a nonspecific therapy for bruxism.32 Based on this, reviews suggest that the use of occlusal splints be restricted to the prevention and/ or limitation of dental damage that is potentially induced by the disorder.4,32 Therefore, it is of interest as to what extent these insights and the resulting scientific recommendations have reached practicing dentists and, moreover, how general dentists (GDs) view bruxism. To date, there have been only a few studies that evaluate the transfer of knowledge from research-
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ers to front-line care providers. These investigations essentially focused on the prescription patterns for occlusal splints.33,34 In 1995, a random sample of US dentists was surveyed to determine the type of occlusal splint most preferred, and the number of splints that were fabricated over the preceding year for bruxism patients. Results indicated that both GDs and dental specialists had made approximately 11 splints in the preceding year. Of the 380 dentists who had made splints for bruxism patients, 14.5% fabricated occlusal splints from only soft materials, 59.4% made only hard acrylic resin splints, and 26.1% varied with respect to their selection of materials.34 Similarly, the outcome of a recent retrospective study in Sweden revealed that the most common indication for the use of hard acrylic resin stabilization splints, as well as for soft splints, was occlusal wear due to bruxism.33 Although several investigations have shown increased electromyographic (EMG) activity in patients wearing soft splints,12,35 the results of the 2 previously mentioned studies show discrepancies between scientific knowledge and the opinion and decisions of practicing dentists in regard to the use and, in particular, the type of occlusal splints prescribed for the management of bruxism.33,34 At present, there is little information available on how German GDs manage bruxism patients using both conservative reversible and irreversible techniques. Likewise, there is little information on the percentage of bruxism patients in German dental practices. Therefore, the purpose of this investigation was to determine the most frequently applied therapies and, in particular, the prescription patterns for occlusal splints used by German GDs and dental specialists for the management of bruxism. Furthermore, the authors made an effort to gather information on the knowledge and opinions of GDs and specialists regarding the role of occlusal interferences, in particular, the development of sleep bruxism. The first
null hypothesis of this study was that there would be no difference among GDs and dental specialists with respect to the most frequently applied therapies; the second null hypothesis was that GDs and dental specialists would not differ regarding the scientific recommendations for the management of bruxism.
MATERIAL AND METHODS A 13-item questionnaire was developed to identify the therapies prescribed most frequently and, particularly, the prescription patterns for occlusal splints used by German GDs and dental specialists for the management of patients diagnosed with bruxism. The questionnaire was mailed along with a cover letter, explaining the purpose of the survey and requesting participation. A stamped, self-addressed envelope was enclosed with the questionnaire and mailed to all active members of the statutory dental insurance providers of the German North Rhine (n=5500; 2006 roster) and the German WestphaliaLippe area (n=4984; 2006 roster). To ensure the anonymity of the respondents, the questionnaires were mailed by the statutory dental insurance providers along with their regular quarterly newsletter. No financial incentive was provided for responding to the survey. The first 5 questions in the questionnaire gathered sociodemographic and descriptive information on the respondents. In addition, respondents were asked to estimate the percentage of patients that were diagnosed with bruxism in their own practices in the past year and the percentage of those patients needing therapy and receiving it. The definition of bruxism was clearly stated as “the involuntary grinding and clenching of the teeth” at the bottom of the first page. The definition was limited not only to keep the questionnaire simple, but also to consider the fact that the present management strategies in many German dental practices differenti-
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Volume 105 Issue 3 ate little between diurnal and sleep bruxism. Respondents were explicitly informed not to include patients diagnosed with craniomandibular disorders. The last question in the first section was to identify whether respondents primarily referred their bruxism patients to other clinicians or to university-based care centers. Respondents who treated bruxism patients themselves were asked to continue the questionnaire. The next 4 questions in the questionnaire requested that respondents specify the percentage of the various therapeutic modalities used, the types and distribution of occlusal splints, and the number of occlusal splints made for the management of bruxism patients. The respondents were further asked to provide details regarding the wear time they most frequently recommended for each type of occlusal splint. With the intention of gaining information on the knowledge and opinions of practicing dentists, in particular, regarding sleep bruxism, the last part of the questionnaire included one statement, “Sleep bruxism is caused by occlusal interferences,” which was derived from a mail survey designed at the University of Wash-
ington and fielded in the Seattle36 and the Kansas City areas.37 Due to the complexity of the questionnaire used in the current study, only one statement relating to the topic of sleep bruxism was taken from the 4 original categories in the University of Washington survey. This statement was derived from the psychophysiological category, which included questions related to the interaction of physical and psychological factors in temporomandibular disorders (TMDs) etiology, diagnosis, and management. Respondents were asked to rate their answer according to an 11-point scale in which 0 represented “strongly disagree,” 10 represented “strongly agree,” and 5 represented a “neutral’” standpoint. In the original Seattle study,36 statements were verified by 2 panels of experts who formed the expert group. As in the Kansas City survey,37 the expert responses used in the Seattle study were also used in the present investigation. A statement was defined as “expert consensus” if more than 75% of the experts in the designated group endorsed either an “agree” (scores 7-10) or a “disagree” response (scores 0-3). Statistical analysis was performed
using statistical software (SPSS, v. 17.0; SPSS, Inc, Chicago, Ill). Normal distribution was tested using the Kolmogorov-Smirnov test along with an assessment of histograms. The Pearson chi-square test was used to determine the significance of differences between 2 independent groups when data consisted of frequencies in discrete categories. For all quantitative variables that were not normally distributed, differences were evaluated by means of the nonparametric Mann-Whitney U test. For all statistical analyses, an alpha error probability of .05 was defined as the statistically significant level.
RESULTS In total, 939 (8.96%) of the 10,484 questionnaires mailed were returned. Six hundred and eighty (72.4%) respondents provided complete data, 12 (1.3%) had filled in only the first section of the questionnaire, and in 247 (26.3%) resubmitted questionnaires, at least one item of the questionnaire was not completed. The largest proportion of responding participants (368 (39.9%) of 922) had 11 to 20 years of professional work experience. Approximately 52% (489)
Table I. Demographic and practice characteristics of respondents Dental Specialists
General Dentists
P
17.75 ± 8.61
18.33 ± 8.77
.516a
Male (n=935)
95 (75.4%)
603 (74.5%)
.836b,c
Age (n=929)
45.57 ± 8.82
45.95 ± 8.55
.514a
Percentage of patients diagnosed with bruxism (n=923)
13.84 ± 14.86
15.79 ± 16.55
.175a
Percentage of bruxism patients needing therapy and receiving it (n=922)
27.86 ± 33.52
32.53 ± 33.27
.020a
Number of years in professional practice (n=922)
.001b
Do you predominantly treat bruxism patients on your own? (n=931) Yes
100 (79.4%)
737 (91.6%)
No
26 (20.6%)
68 (8.4%)
aMann-Whitney U test; data are presented as mean ± standard deviation (SD). bChi-square test cOne respondent failed to report his/her gender.
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March 2011 of the returned questionnaires were from members of the statutory dental insurance providers of the German North Rhine, and 47.6% (444) were practitioners in the Westphalia-Lippe area. Significantly more male than female dentists returned the questionnaire, 74.2% (699) versus 25.4% (239) (chi-square test, P=.004). This respondent distribution is consistent with the approximate gender distribution of practicing dentists in both statutory dental insurance provider groups (30.0% female in the German North Rhine area and 29.0% female in the Westphalia-Lippe area) and is thus representative of the population of dentists in the former West German federal states. Some of the demographic and descriptive characteristics of the respondents, classified as dental specialists and GDs, are shown in Table I. One hundred and twenty-eight (13.6%) of the respondents were dental specialists, and 811 (86.4%) were GDs. Forty-three orthodontists represented the largest proportion of specialists (33.6%), followed by 24 dentists with
postgraduate qualifications in oral implantology (18.8%) and 19 oral surgeons (14.8%). Further specialist groups included 13 oral and maxillofacial surgeons (10.2%), 9 periodontists (7%), 3 prosthodontists (2.3%), 2 endodontists (1.6%), 2 specialists in preventive and restorative dentistry (1.6%), 1 pediatric dentist (0.8%), and 12 others (9.4%). Table II shows the average percentage of patients for whom respondents reported prescribing one of the 10 most common therapies for the management of bruxism. Occlusal splints were by far the most frequently prescribed, followed by relaxation techniques, occlusal equilibration, physiotherapy, and prosthodontic reconstruction. In the preceding year, a GD made an average of 27.5 occlusal splints (SD, 31.85; range, 0 to 300) while a dental specialist made an average of 19.8 occlusal splints (SD, 37.37; range, 0 to 300) (Mann-Whitney U test, P<.001). The number of occlusal splints made in the preceding year, divided into 6 categories (0 occlusal splints, or 1-10, 11-50, 51-100,
101-200, or 201-300) revealed a statistically significant group difference (chi-square test, P<.001). As seen in Figure 1, the majority of respondents in both groups fabricated 50 or fewer occlusal splints in the preceding year. With respect to prescription patterns for the different splint types, Table III provides the average percentage of patients treated by GDs and dental specialists with different types of occlusal splints. The most frequently used splint type was the occlusal stabilization splint with canine protected articulation, followed by the occlusal splint with group function and the unadjusted hard splint. Table IV shows, for the respective type of occlusal splint, the percentage of respondents who recommended splint use for 24 hours, only at night, if required, or various combinations of usage times. As seen from Table IV, there is considerable agreement between GDs and dental specialists as to the prescribed usage times. For all types of occlusal splints, the most frequently recommended use was at night. With respect to the opinions of
Table II. Average percentage of patients treated with the most frequent therapies for bruxism Patients of Dental Specialists
Patients of General Dentists
P
Occlusal splints (n=909: 120 dental specialists and 789 GDs)
52.37%
73.11%
.001
Relaxation techniques (n=914: 120 dental specialists and 794 GDs)
17.19%
14.51%
.880
Occlusal equilibration (n=914: 120 dental specialists and 794 GDs)
7.23%
9.20%
.003
Physiotherapy (n=918: 120 dental specialists and 798 GDs)
8.35%
6.70%
.579
Prosthodontic reconstruction (n=911: 120 dental specialists and 791 GDs)
4.03%
5.59%
.004
Orthodontics (n=917: 120 dental specialists and 797 GDs)
7.28%
0.65%
.001
Psychotherapy (n=918: 121 dental specialists and 797 GDs)
2.99%
2.32%
.847
Thermal packs (n=918: 121 dental specialists and 797 GDs)
1.97%
1.34%
.617
Medications (n=919: 121 dental specialists and 798 GDs)
1.33%
1.10%
.411
Diet counseling (n=918: 121 dental specialists and 797 GDs)
0.50%
1.71%
.264
Miscellaneous (n=915: 122 dental specialists and 793 GDs)
4.02%
2.48%
.311
Therapy
Mann-Whitney U test was used to assess differences between dental specialists and GDs.
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Number of Responding Practicing Dentists
500 Dental specialists
416
400
GDs
300 215
200 100 0
43 48
0
31
1-10
33
11-50
58 10
2
18
1
1
51-100 101-200 201-300
Number of Occlusal Splints 1 Number of occlusal splints made by responding dentists in preceding year is shown following classification into 6 groups. Majority of both groups fabricated 50 or fewer occlusal splints in preceding year.
Table III. Average percentage of patients treated with various occlusal splint types Patients of Dental Specialists
Patients of General Dentists
P
Stabilization splint with canine protected articulation (n=910: 120 dental specialists and 789 GDs)
32.98%
42.49%
.018
Occlusal splint with group function (n=913: 122 dental specialists and 791 GDs)
10.06%
16.54%
.001
Unadjusted hard splint (n=913: 122 dental specialists and 791 GDs)
8.63%
16.45%
.009
Unadjusted soft splint (n=916: 122 dental specialists and 794 GDs)
7.28%
8.23%
.719
Repositioning splint (n=914: 122 dental specialists and 792 GDs)
5.22%
3.34%
.517
Reflex splint with anterior ramp (n=915: 122 dental specialists and 793 GDs)
1.20%
1.80%
.269
Type of Occlusal Splint
Mann-Whitney U test was used to assess differences between dental specialists and GDs.
practicing dentists pertaining to the etiology of sleep bruxism, the initial analysis revealed no statistically significant differences between the responses of GDs (47.0% disagree) and dental specialists (52.1% disagree) compared to the expert opinions (chisquare test, P=.513). For this reason, the opinions of both the responding GDs and the responding specialists were combined and their responses compared to the experts’ opinion. As shown in Figure 2, 85% of the experts
disagreed with the statement that “sleep bruxism is caused by occlusal interferences,” and only 47.7% of the practicing dentists had the same opinion as the experts. This difference between the experts and the responding practicing dentists was statistically significant (chi-square test, P=.021). Apart from this disagreement between the practicing dentists and the experts, 28.6% of the practicing dentists had a neutral opinion and thus expressed their uncertainty
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about the statement. To compare the present opinion of German practicing dentists with results derived from a preceding survey, the responses of the practicing dentists received in the Kansas City study37 are also shown in Figure 2. As derived from this comparison, the disagreement of the practicing dentists surveyed in the current study was approximately 15% greater than the disagreement of practicing dentists questioned 20 years ago in the Kansas City area.
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March 2011
Table IV. Number (%) of respondents who recommend various application durations for different occlusal splint types Dental Specialists (%) Type of Occlusal Splint Stabilization splint with canine protected articulation
At Night
24 h
If Required
General Dentists (%)
Diverse Combinations
At Night
24 h
If Required
Diverse Combinations
P .506
5
33
5
7
34
341
21
44
(10.0)
(66.0)
(10.0)
(14.0)
(7.7)
(77.5)
(4.8)
(10.0)
(n=490: 50 dental specialists and 440 GDs) Occlusal splint with group function
2
11
1
4
20
176
15
21
(11.1)
(61.1)
(5.6)
(22.3)
(8.6)
(75.9)
(6.5)
(9.0)
.628
(n=250: 18 dental specialists and 232 GDs) Unadjusted hard splint (n=267: 25 dental specialists
1
20
3
1
11
193
20
18
(4.0)
(80.0)
(12.0)
(4.0)
(4.5)
(79.8)
(8.3)
(7.4)
.934
and 242 GDs) Repositioning splint (n=106: 12 dental specialists
5
5
0
2
27
55
7
5
(41.7)
(41.7)
(0)
(16.7)
(28.7)
(58.5)
(7.4)
(5.3)
.079
and 94 GDs) Unadjusted soft splint (n=180: 19 dental specialists
1
6
2
0
12
114
25
10
(5.3)
(84.2)
(10.5)
(0)
(7.5)
(70.8)
(15.5)
(6.2)
.736
and 161 GDs) Reflex splint with anterior ramp
1
3
2
0
7
42
9
6
(16.7)
(50.0)
(33.3)
(0)
(10.9)
(65.6)
(14.1)
(9.4)
(n=70: 6 dental specialists and 64 GDs) Chi-square test was used to determine significance of differences between dental specialists and GDs.
Percent of Disagree
100 80
P=.021 85.0%
Statement: “Sleep bruxism is caused by occlusal interferences” (n=915)
60 47.7%
40
33.0%
20 0
Expert Response (Le Resche et al.36)
Responding Dentists (Present Survey)
Practicing Dentists (Glaros et al.37)
Surveys 2 Percentage of responding dentists agreeing with expert response regarding statement on sleep bruxism. To compare present opinion of German practicing dentists with results derived from preceding survey, responses of practicing dentists received in Kansas City study are also shown.
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.694
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Volume 105 Issue 3 DISCUSSION
The purpose of the present study was to evaluate whether GDs and dental specialists differ with respect to their most frequently applied therapies for the management of bruxism. The results of this study indicate that in 4 of the 10 most frequently prescribed therapies, GDs and dental specialists differed to a statistically significant extent. Moreover, significant discrepancies between the 2 groups were found in the average number of occlusal splints made in the preceding year and the type of occlusal splints that were prescribed. Therefore, the null hypothesis that there is no difference among GDs and dental specialists with respect to the most frequently applied therapies was rejected. A second objective of the present study was to identify whether the surveyed GDs and dental specialists differ regarding the scientific recommendations for the management of bruxism. The findings of this investigation confirm agreement of practicing dentists with the current scientific recommendations; most respondents indicated that the management of bruxism should predominantly be conservative and reversible.4,29-31 For both GDs and dental specialists, occlusal splints were the first-choice treatment, followed by relaxation techniques. However, apart from these reversible techniques, an appreciable number of practicing dentists still use irreversible techniques, such as occlusal adjustment, prosthodontic restoration, or orthodontics, for the management of bruxism. For example, GDs were found to manage approximately 9% of their bruxism patients with occlusal equilibration. A potential explanation for this finding might be that this irreversible technique is recommended by a few authors,6-8 although their suggestions are predominantly based on opinions and subjective clinical experiences and less on well-founded scientific data. However, considering that, on average, rsponding practicing dentists graduated 18 years prior
to this study, and given that substantial changes in the field occurred during this period, these findings may indicate a delayed transfer of knowledge from researchers to front-line care providers. Extending the topic of bruxism in postdoctoral courses will promote transfer of knowledge and thus will support clinicians in their daily decision-making process. Most importantly, there is a need to discover the definitive underlying etiology of bruxism and, accordingly, the causeoriented management approaches. Based on available literature on bruxism, occlusion is known to have only a minor role in the development of bruxism,23 if any.4,23,29,31 Moreover, as shown by various review articles, there is no high-quality, evidencebased support for the use of irreversible techniques.4,9,10,29,31 Therefore, the null hypothesis that both GDs and dental specialists do not differ from scientific recommendations regarding the management of bruxism is rejected. With regard to the type of occlusal splint prescribed by practicing dentists, the responses of the present survey are largely consistent with the current view of scientific dental experts. While various authors have reported on the efficacy of occlusal stabilization splints, the clinical results obtained were not found to be superior to those obtained for other types of splints.13,14 There is, however, one exception: the use of soft splints. The present investigation revealed that on average, 8% of the practicing dentists prescribe unadjusted soft splints for the management of their bruxism patients, even though the data of 2 studies indicate that soft splint material may actually increase bruxism activity in some patients.12,35 Although hard splints are suggested to be more effective in reducing bruxism activity,11,12 it appears that the traditional decision-making process of dentists in this study, which is similar to that of Swedish dentists,33,38 is based on knowledge gained through individual past experience, practice traditions,
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and the opinions of recognized authorities. Given the conflicting results on the clinical efficacy and effectiveness of occlusal splints and the lack of knowledge regarding the potentially underlying mechanisms that explain their apparent success in the management of bruxism, it is reasonable to view the occlusal splint primarily as a nonspecific therapy for bruxism. Therefore, reviews suggest that the use of occlusal splints be limited to the prevention and/or limitation of dental damage potentially induced by the disorder.4,29,32 To gain information on dentists’ belief regarding the role of occlusal interferences on the development of sleep bruxism, the survey used in the current study included one statement derived from a mailed survey that was designed at the University of Washington and fielded in the Seattle area.36 Although the statement was developed in 1993, its validity was verified by a panel of experts in 200738 and in various scientific publications.4,19,20,22,23,31,32,39 In the present study, no difference in opinion was found between the GDs and dental specialists; however, there was a considerable discrepancy between the responding practicing dentists and the experts. Furthermore, it should be noted that, on average, 30% of the practicing dentists had a neutral opinion. This finding could be interpreted as tacit uncertainty instead of open disagreement with the expert opinion. The uncertainty might stem from a lack of information or from knowledge of arguments on both sides of the issue and, consequently, an ambiguous opinion. As has been previously discussed, the finding with respect to this statement also points to a discrepancy between what is known by scientific researchers in the area of bruxism and what is believed by practicing dentists. The present investigation includes some shortcomings that must be considered when data are interpreted. First, within this survey, some percentages did not add up to 100 per-
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March 2011 cent. This arises from the effect of rounding and the fact that some respondents failed to answer all of the questions on the survey. Secondly, the response rate in the present study, when compared to that of a previous survey performed in the US, appeared relatively low and, therefore, a response bias might have influenced the outcome of this investigation. Nevertheless, the lack of gender differences between GDs and dental specialists and the close approximation of the respondents’ gender distribution to that of the original study sample and the former West German federal states dentist population corroborate the validity of the data. Accordingly, data obtained from the responding practicing dentists can be regarded as representative. The low response rate could be attributed to the complexity of the survey, as the questionnaire consisted of 3 sections that dealt with diverse issues. Another possible explanation might be that, compared to dentists in the US, German dentists are, in general, less trained and less familiar with surveys. In addition, this was the first survey on the topic of bruxism. Apart from that, in the US, there appears to be a general interest in data collection and, consequently, the willingness to participate in a survey is stronger than it is in Germany. Moreover, in contrast to previous surveys of dentists in the US, this investigation was performed anonymously (as is usual in diverse German surveys) and, therefore, there was neither a chance to remind nonrespondents via telephone, nor did the participants receive any financial incentive to participate.
CONCLUSIONS Practicing dentists seem to concur with current scientific recommendations, expressing the opinion that the management of bruxism should predominantly be conservative and reversible. However, the findings reveal diverse differences between GDs and dental specialists concerning the
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most frequently prescribed therapies, the average number of occlusal splints made in the preceding year, and the type of occlusal splints used. Moreover, the discrepancies detected in some areas, such as the use of irreversible techniques or the use of soft splints, emphasize the need to more quickly transfer new knowledge in the field of bruxism from researchers to practicing dentists.
REFERENCES 1. American Academy of Sleep Medicine. The international classification of sleep disorders, revised: diagnostic and coding manual. 2nd ed. Westchester: American Academy of Sleep Medicine; 2005. p. 189-92. 2. American Academy of Orofacial Pain. Orofacial pain: guidelines for assessment, diagnosis and management. In: de Leeuw R, editor. 4 th ed. Chicago: Quintessence; 2008. p. 257-300. 3. The glossary of prosthodontic terms. J Prosthet Dent 2005;94:19. 4. Lobbezoo F, van der Zaag J, van Selms MK, Hamburger HL, Naeije M. Principles for the management of bruxism. J Oral Rehabil 2008;35:509-23. 5. Ramfjord SP. Bruxism, a clinical and electromyographic study. J Am Dent Assoc 1961;62:21-44. 6. Ash MM Jr. Occlusion, TMDs, and dental education. Head Face Med 2007;3:1. 7. Christensen GJ. Treating bruxism and clenching. J Am Dent Assoc 2000;131:233-5. 8. Christensen GJ. The major part of dentistry you may be neglecting. J Am Dent Assoc 2005;136:497-9. 9. Clark GT, Tsukiyama Y, Baba K, Watanabe T. Sixty-eight years of experimental occlusal interference studies: what have we learned? J Prosthet Dent 1999;82:704-13. 10.Tsukiyama Y, Baba K, Clark GT. An evidence-based assessment of occlusal adjustment as a treatment for temporomandibular disorders. J Prosthet Dent 2001;86:57-66. 11.al-Quran FA, Lyons MF. The immediate effect of hard and soft splints on the EMG activity of the masseter and temporalis muscles. J Oral Rehabil 1999;26:559-63. 12.Okeson JP. The effects of hard and soft occlusal splints on nocturnal bruxism. J Am Dent Assoc 1987;114:788-91. 13.Rugh JD, Graham GS, Smith JC, Ohrbach RK. Effects of canine versus molar occlusal splint guidance on nocturnal bruxism and craniomandibular symptomatology. J Craniomandib Disord 1989;3:203-10. 14.Türp JC, Komine F, Hugger A. Efficacy of stabilization splints for the management of patients with masticatory muscle pain: a qualitative systematic review. Clin Oral Investig 2004;8:179-95.
15.Ommerborn MA, Giraki M, Schneider C, Schäfer R, Gotter A, Franz M, et al. A new analyzing method for quantification of abrasion on the Bruxcore device for sleep bruxism diagnosis. J Orofac Pain 2005;19:232-8. 16.Yoshimi H, Sasaguri K, Tamaki K, Sato S. Identification of the occurrence and pattern of masseter muscle activities during sleep using EMG and accelerometer systems. Head Face Med 2009;5:7. 17.Ahlberg J, Rantala M, Savolainen A, Suvinen T, Nissinen M, Sarna S, et al. Reported bruxism and stress experience. Community Dent Oral Epidemiol 2002;30:405-8. 18.Kampe T, Edman G, Bader G, Tagdae T, Karlsson S. Personality traits in a group of subjects with long-standing bruxing behaviour. J Oral Rehabil 1997;24:588-93. 19.Kato T, Thie NM, Huynh N, Miyawaki S, Lavigne GJ. Topical review: sleep bruxism and the role of peripheral sensory influences. J Orofac Pain 2003;17:191-213. 20.Lavigne GJ, Kato T, Kolta A, Sessle BJ. Neurobiological mechanisms involved in sleep bruxism. Crit Rev Oral Biol Med 2003;14:30-46. 21.Lobbezoo F, Lavigne GJ, Tanguay R, Montplaisir JY. The effect of catecholamine precursor L-dopa on sleep bruxism: a controlled clinical trial. Mov Disord 1997;12:73-8. 22.Lobbezoo F, Naeije M. Bruxism is mainly regulated centrally, not peripherally. J Oral Rehabil 2001;28:1085-91. 23.Lobbezoo F, Rompre PH, Soucy JP, Iafrancesco C, Turkewicz J, Montplaisir JY, et al. Lack of associations between occlusal and cephalometric measures, side imbalance in striatal D2 receptor binding, and sleeprelated oromotor activities. J Orofac Pain 2001;15:64-71. 24.Macaluso GM, Guerra P, Di Giovanni G, Boselli M, Parrino L, Terzano MG. Sleep bruxism is a disorder related to periodic arousals during sleep. J Dent Res 1998;77:565-73. 25.Ohayon MM, Li KK, Guilleminault C. Risk factors for sleep bruxism in the general population. Chest 2001;119:53-61. 26.Ommerborn MA, Schneider C, Giraki M, Schafer R, Handschel J, Franz M, et al. Effects of an occlusal splint compared with cognitive-behavioral treatment on sleep bruxism activity. Eur J Oral Sci 2007;115:7-14. 27.Schneider C, Schaefer R, Ommerborn MA, Giraki M, Goertz A, Raab WH, et al. Maladaptive coping strategies in patients with bruxism compared to non-bruxing controls. Int J Behav Med 2007;14:257-61. 28.Ommerborn MA, Schneider C, Giraki M, Schafer R, Singh P, Franz M, et al. In vivo evaluation of noncarious cervical lesions in sleep bruxism subjects. J Prosthet Dent 2007;98:150-8. 29.Attanasio R. An overview of bruxism and its management. Dent Clin North Am 1997;41:229-41. 30.Greene CS, Klasser GD, Epstein JB. ‚Observations‘ questioned. J Am Dent Assoc 2005;136:856, 858; author reply 858.
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Volume 105 Issue 3 31.Lavigne GJ, Khoury S, Abe S, Yamaguchi T, Raphael K. Bruxism physiology and pathology: an overview for clinicians. J Oral Rehabil 2008;35:476-94. 32.Dao T T, Lavigne GJ. Oral splints: the crutches for temporomandibular disorders and bruxism? Crit Rev Oral Biol Med 1998;9:345-61. 33. Lindfors E, Magnusson T, Tegelberg A. Interocclusal appliances--indications and clinical routines in general dental practice in Sweden. Swed Dent J 2006;30:123-34. 34.Pierce CJ, Weyant RJ, Block HM, Nemir DC. Dental splint prescription patterns: a survey. J Am Dent Assoc 1995;126:248-54. 35.Harkins S, Marteney JL, Cueva O, Cueva L. Application of soft occlusal splints in patients suffering from clicking temporomandibular joints. Cranio 1988;6:71-6.
36.Le Resche L, Truelove EL, Dworkin SF. Temporomandibular disorders: a survey of dentists‘ knowledge and beliefs. J Am Dent Assoc 1993;124:90-4, 97-106. 37.Glaros AG, Glass EG, McLaughlin L. Knowledge and beliefs of dentists regarding temporomandibular disorders and chronic pain. J Orofac Pain 1994;8:216-22. 38.Tegelberg A, Wenneberg B, List T. General practice dentists’ knowledge of temporomandibular disorders in children and adolescents. Eur J Dent Educ 2007;11:216-21. 39.Lavigne GJ, Manzini C, Kato T. Sleep bruxism. In: Kryger MH, Roth T, Dement WC, editors. Principles and practice of sleep medicine. 4 th ed. Philadelphia: Elsevier/ Saunders; 2005. p. 946-59.
Corresponding author: Dr Michelle A. Ommerborn Department of Operative Dentistry, Periodontology and Endodontics Heinrich-Heine-University Moorenstr. 5 40225 Düsseldorf GERMANY Fax: +49 211 81 04021 E-mail: [email protected] Acknowledgments The authors thank the statutory dental insurance providers of the German North Rhine area and the German Westphalia-Lippe area for their kind support in sending out the questionnaires. Copyright © 2011 by the Editorial Council for The Journal of Prosthetic Dentistry.
Noteworthy Abstracts of the Current Literature A 15-year clinical comparative study of the cumulative survival rate of cast metal core and resin core restorations luted with adhesive resin cement Hikasa T, Matsuka Y, Mine A, Minakuchi H, Hara ES, Van Meerbeek B, Yatani H, Kuboki T. Int J Prosthodont. 2010 Sep-Oct;23(5):397-405. Purpose. The aim of this study was to compare the core survival rates (CSRs) of cast metal versus resin core restorations luted with adhesive resin cement, as well as to determine the risk factors for core failure. Materials and Methods. Nine hundred ninety-one patients (2,124 cores) who received either cast metal or resin cores luted with adhesive resin cement at the Fixed Prosthodontic Clinic of Okayama University Dental Hospital between April 1988 and December 1991 and whose structured clinical core record was filled appropriately comprised the study subjects. The clinical core record included information regarding patient age, sex, core restoration type, tooth location, tooth type, remaining coronal dentin, and root canal form. CSRs, as well as causes for failure, were analyzed 15 years postinsertion. Since 381 patients lacked data regarding predictors for core failure, a subsample of 610 patients (1,053 cores) was used for the subsequent risk factor analysis. Results. The cumulative CSR of resin cores (78.7%) was significantly higher than that of cast metal cores (55.4%; log-rank test, P < .0001). The Cox proportional hazards test revealed that sex (male, P < .0001), absence of remaining coronal dentin (P = .0057), core restoration type (cast metal, P = .0186), and higher age at core insertion (P = .0380) were significant predictors for core failure. The incidence of complications, such as core loosening (P = .0016) and tooth extraction (P < .0001), was significantly higher in cast metal cores. Conclusions. Cast metal cores were associated with a significantly lower CSR than resin cores, and significant risk factors for core failure were sex (male), absence of remaining coronal dentin, core restoration type (cast metal), and higher age at core insertion. Reprinted with permission of Quintessence Publishing.
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