JADA Continuing Education: The effects of periodontal curette handle weight and diameter on arm pain: A four-month randomized controlled trial.

Article (PDF Available)inJournal of the American Dental Association (1939) 143(10):1105-13 · October 2012with79 Reads
DOI: 10.14219/jada.archive.2012.0041 · Source: PubMed
Abstract
/st> The design of periodontal curette handles may cause or aggravate arm pain in dental practitioners. The authors conducted a four-month randomized controlled trial to evaluate the effects of curette handle diameter and weight on arm pain among dental hygienists and dentists. /st> One hundred ten dental hygienists and dentists who performed scaling, root planing or dental prophylaxis procedures participated in this study. The authors assessed right wrist/hand, elbow/forearm and shoulder pain levels weekly. They randomized participants to receive either a set of light (14 grams) periodontal curettes with a large diameter (11 millimeters) or a set of heavy (34 g) periodontal curettes with a narrow diameter (8 mm). The authors compared changes in mean pain scores across the study period between intervention groups by using general linear models and controlling for covariates. /st> The improvement in pain scores across the three body regions was greater for participants who used the lighter, wider-diameter curettes. In the final adjusted model, the differences were statistically significant only for the shoulder region (P = .02). /st> The study results show that dental instrument design has an effect on upper-extremity pain in dental practitioners. Using a lighter instrument with a wider diameter may be an easy and cost-effective intervention to reduce or prevent upper-extremity pain associated with dental hygiene procedures. Clinical implications To prevent or reduce arm pain, practitioners should consider using lightweight instruments with large diameters when performing scaling and root planing procedures.
W
ork disability and
decreased productivity
due to musculoskeletal
disorders of the hands
and arms are common problems
among dentists and dental hygien-
ists.
1-11
A survey conducted by the
American Dental Association
12
showed that 9.2 percent of 2,983
responding dentists had received
diagnoses of upper-extremity
musculoskeletal disorders; of these,
approximately 20 percent required
surgery and more than 40 percent
reduced their work hours. A survey
of dentists in the United Kingdom
found that 29.5 percent of prema-
ture retirements were the result of
similar problems.
13
Pain in the right wrist, elbow and
shoulder appears to be the problem
that most interferes with dental
procedures. The prevalence of right
arm symptoms among dentists and
dental hygienists ranges from 19 to
61 percent.
9,14,15
Carpal tunnel syn-
drome, one of the more disabling
disorders that affects the hand, is
more common among dental practi-
tioners than it is among people in
most other occupations.
16
Carpal tunnel syndrome and
other hand and arm disorders are
associated with factors both personal
(for example, female sex, obesity,
diabetes, age) and workplace-related
(for example, repetitive forceful
Dr. Rempel is a professor of medicine, Division of Occupational and Environmental Medicine, University of California, San Francisco, 1301 S. 46th St.,
Building 163, Richmond, Calif. 94804, e-mail david.rempel@ucsf.edu. Address reprint requests to Dr. Rempel.
Dr. Lee is a research scientist, Division of Occupational and Environmental Medicine, University of California, San Francisco.
Ms. Dawson is a research associate, School of Dentistry, University of California, San Francisco.
Dr. Loomer is a professor, Department of Orofacial Sciences, School of Dentistry, University of California, San Francisco.
The effects of periodontal curette handle
weight and diameter on arm pain
A four-month randomized controlled trial
David Rempel, MD, MPH; David L. Lee, ScD; Katie Dawson, RDH; Peter Loomer, DDS, PhD
A B S T R A C T
Background. The design of periodontal
curette handles may cause or aggravate arm
pain in dental practitioners. The authors con-
ducted a four-month randomized controlled trial
to evaluate the effects of curette handle diameter
and weight on arm pain among dental hygienists and
dentists.
Methods. One hundred ten dental hygienists and dentists who
performed scaling, root planing or dental prophylaxis procedures
participated in this study. The authors assessed right wrist/hand,
elbow/forearm and shoulder pain levels weekly. They randomized
participants to receive either a set of light (14 grams) periodontal
curettes with a large diameter (11 millimeters) or a set of heavy
(34 g) periodontal curettes with a narrow diameter (8 mm). The
authors compared changes in mean pain scores across the study
period between intervention groups by using general linear models
and controlling for covariates.
Results. The improvement in pain scores across the three body
regions was greater for participants who used the lighter, wider-
diameter curettes. In the final adjusted model, the differences were
statistically significant only for the shoulder region (P = .02).
Conclusions. The study results show that dental instrument
design has an effect on upper-extremity pain in dental practi-
tioners. Using a lighter instrument with a wider diameter may be
an easy and cost-effective intervention to reduce or prevent upper-
extremity pain associated with dental hygiene procedures.
Clinical implications. To prevent or reduce arm pain, practi-
tioners should consider using lightweight instruments with large
diameters when performing scaling and root planing procedures.
Key Words. Musculoskeletal disorders; pain; ergonomics;
shoulder; dental instrument design; occupational; intervention;
periodontitis.
JADA 2012;143(10):1105-1113. ClinicalTrials.gov identifier
NCT01332760.
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R E S E A R C H
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pinching or gripping, sustained nonneutral wrist
positions and use of vibrating tools).
9,17-19
For
dental practitioners, periodontal scaling and root
planing may pose the most important risk.
20,21
The results of a study of pinch force in a clinical
setting show that dentists applied repeated
mean (standard deviation [SD]) peak pinch
forces of 24.5 (4.1) newtons during periodontal
scaling and root planing procedures.
22
This may
be a primary cause of hand and arm disorders
and pain. In studies of industrial workers, inves-
tigators have found that repeated pinch forces of
more than 10 N (1 kilogram of force) were asso-
ciated with an increased risk of experiencing
wrist, elbow and shoulder disorders.
19,23-25
Modifications to work practices that reduce
the applied pinch force may play a role in pre-
venting hand and arm disorders among dental
practitioners. Researchers in a recent laboratory
study found that using lighter (15 versus 24
grams) or larger-diameter (10 versus 7 millime-
ters) instruments reduced the peak pinch force
applied during scaling on a typodont by 23
and 17 percent, respectively.
26
Ozawa and col-
leagues
27
found that the use of a larger-
diameter endodontic instrument handle
(6.0 mm versus 3.5 mm) was associated with
decreased forearm muscle activity.
To our knowledge, no systematic workplace
intervention studies have been conducted to
identify work practices or dental instrument
designs that may prevent musculoskeletal disor-
ders or decrease arm pain among dental practi-
tioners. The purpose of this randomized con-
trolled trial (RCT) was to evaluate the effects of
periodontal instrument handle diameter and
weight on arm pain among dentists and dental
R E S E A R C H
ABBREVIATION KEY. RCT: Randomized controlled
trial.
TABLE 1
Demographic and preintervention characteristics of study participants
(N = 110).
CHARACTERISTIC NO. OF PARTICIPANTS*
Heavy Instrument,
Narrow Handle
(n = 56)
Light Instrument,
Wide Handle
(n = 54)
Mean (SD
) Age, Years
42.9 (10.8) 46.6 (9.8)
Sex
Female
49 51
Male
7 3
Occupation
Dentist
6 7
Dental hygienist
50 47
Years in Practice
1-5
16 7
> 5
40 47
Dental Scaling/Root Planing per Week, Hours
< 20
14 14
20-30
19 20
> 30
23 20
Mean (SD) Percentage of Time Using Hand Scaler
62.5 (18.9) 65.7 (23.4)
Mean (SD) Percentage of Time Using Ultrasonic Scaler
39.8 (20.6) 37.5 (24.2)
Mean (SD) No. of Days per Week Performing Dental
Procedures
3.7 (0.9) 3.6 (1.1)
Mean (SD) No. of Hours per Day Performing Dental
Procedures
7.9 (0.7) 7.9 (0.8)
Mean (SD) No. of Patients Treated in Eight-Hour Period
7.8 (1.8) 8.3 (1.2)
Second Dental Job
12 14
Physician-Diagnosed Upper-Extremity Disorder
8 10
* Unless otherwise specified.
SD: Standard deviation.
Wrist tendonitis, carpal tunnel syndrome, Raynaud disease, epicondylitis, rotator cuff injury or cervical radiculopathy. Participants were
not being treated for these conditions at the time of the study.
§ 0 indicates no pain and 10, unbearable pain.
Calculated from reported hours performing scaling or root planing on a weekly questionnaire during the four-week preintervention period.
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hygienists who perform scaling and root planing
procedures. Our hypothesis was that a lighter,
larger-diameter periodontal instrument would
result in less arm pain than that resulting from
use of the more traditional heavier instrument
with a small diameter.
METHODS
We conducted a four-month cluster RCT with
randomization at the level of the dental office.
We recruited dentists and dental hygienists
from the greater San Francisco Bay Area to par-
ticipate in the study. The University of Cali-
fornia, San Francisco, Committee on Human
Research approved the study design, and all
participants signed consent forms. The study
took place between April 2009 and February
2011.
Dentists and dental hygienists were eligible
to participate if they performed scaling and root
planing or teeth cleaning for more than 10
hours per week and had been doing this work
for more than one year. They were not eligible if
they were receiving care from a physician for
treatment of an upper-extremity disorder. We
recruited participants at local dental profes-
sional meetings.
Participants completed an online baseline
questionnaire from which we collected demo-
graphic data and work history information.
They then completed an online questionnaire at
the end of every workweek (Thursday or Friday)
for the next five months. The weekly question-
naire assessed the participant’s maximum pain
level (on a 0- to 10-point scale, with anchors at 0
[“no pain”] and 10 [“unbearable pain”]) for the
right wrist and hand, right elbow and forearm,
and right shoulder. The questionnaire also
assessed the number of hours during the week
that the participant performed different dental
tasks; the number of nights during which he or
she awakened with numbness in the right
thumb, index finger or middle finger; and the
number of days during which the participant
used pain medication for right–upper-extremity
symptoms.
R E S E A R C H
TABLE 1 (CONTINUED)
CHARACTERISTIC NO. OF PARTICIPANTS*
Heavy Instrument,
Narrow Handle
(n = 56)
Light Instrument,
Wide Handle
(n = 54)
Pain, Stiffness, Ache in Previous Month
Right shoulder
5 10
Right elbow/forearm
7 9
Right hand/wrist
15 12
Any Difficulty in Previous Four Months Because of Upper-
Extremity Problem
Using usual technique for work
13 17
Doing usual work
9 19
Doing work as well as you would like
15 17
Spending usual amount of time doing work
11 15
Earning sufficient income
5 4
Always or Often Physically Exhausted After Work
16 23
General Health Very Good or Excellent
42 45
Race/Ethnicity
Asian or Pacific Islander
8 15
African American, not of Hispanic origin
1 2
Hispanic
8 3
White, not of Hispanic origin
36 32
Other
3 2
Mean (SD) Preintervention Pain
(0-10 Scale
§
)
Right shoulder
1.9 (1.3) 2.2 (1.5)
Right elbow/forearm
1.7 (1.3) 1.8 (1.3)
Right hand/wrist
1.9 (1.4) 2.3 (1.4)
Mean (SD) Hours per Week Performing Scaling or Root
Planing
10.7 (8.2) 11.3 (6.7)
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One month after the start of the study, we
randomly assigned participants to one of two
types of periodontal instruments for the re-
maining four months of the study. Randomiza-
tion was at the level of the dental office. If two
or more participants worked in the same office,
we assigned the same instrument to them to
minimize contamination bias. A postdoctoral
fellow made computer-generated random
assignments. We concealed intervention alloca-
tion from the researchers who recruited partici-
pants (K.D., P.L.). The one-month run-in period
before the intervention allowed participants to
become accustomed to the questionnaire and
provided us with baseline arm pain data. We
instructed participants not to discuss the study
or their impressions of the assigned instru-
ments with dental personnel inside or outside of
their office.
Instruments. Instrument 1 weighed 14 g
(with curette tips) and had an 11-mm–diameter
handle; instrument 2 weighed 34 g and had an
8-mm–diameter handle (Figure 1). We selected
the instrument diameters and weights on the
basis of previous laboratory study results
26
to
provide a practical range that would have an
effect on pinch force. The instruments were
custom manufactured and surfaced with a
medium diamond texture. Instrument 1 was
made from black plastic (acetal resin, Delrin,
DuPont, Wilmington, Del.), and instrument 2
was made from steel plated with black coating.
All instruments were fitted with an R3S and an
R4S tip (Ratcliff stainless steel universal
scalers, G. Hartzell & Son, Concord, Calif.).
We informed participants that the study
involved evaluation of a new periodontal instru-
ment, but they did not know what design
elements were being compared. Therefore,
participants were effectively masked to the
intervention. The cluster randomization, at the
level of the dental office, also helped maintain
masking and minimized contamination. Partici-
pants received as many of the instruments as
they needed for their practice; the typical
number requested ranged from four to eight. We
instructed participants to sterilize and sharpen
the assigned instruments as they did for their
own instruments. At the end of the study, par-
ticipants completed an online exit survey, the
results of which enabled us to assess their opin-
ions about the instrument to which they were
assigned.
Primary and secondary outcomes. The
primary outcomes tested were change in mean
pain score, in the right wrist, elbow and
shoulder, from the month before the interven-
tion to the last month of the study after we
adjusted for important covariates. We compared
differences in pain score changes between the
two intervention groups by using general linear
models (SAS version 10, SAS, Cary, N.C.) and
by controlling for age, sex, occupation and hours
of instrument use per week. The analyses fol-
lowed an intent-to-treat approach. We tested the
effect of interaction between instrument and
sex, instrument and age, and instrument and
occupation. We based sample size calculations
on an estimated mean (SD) shoulder pain score
of 2.9 (1.6) (obtained from preliminary studies).
For a type I error of 5 percent, a total of 82 par-
ticipants (41 in each group) would be needed to
have 80 percent power to detect a difference of
1.0 point (33 percent) between groups in the
mean pain score change. To account for covari-
ates and dropouts, we increased the recruitment
goal to 120. Ultimately, we recruited 120 partici-
pants, but only 110 met the inclusion criteria.
We used the t test to compare secondary out-
comes (that is, nights awakened by finger
numbness, days of medication use for pain) for
the subset of participants who reported these
outcomes.
RESULTS
The 110 participants (13 dentists and 97 dental
hygienists) worked at 90 dental offices. The
greatest number of participants in any one
dental office was three. The mean (SD) age of
participants was 44.7 (10.4) years and 100 par-
ticipants (91 percent) were female. The similar
distribution of demographic and other charac-
teristics between the two intervention groups
demonstrates baseline comparability (Table 1,
pages 1106-1107).
Five participants dropped out of the study
between two and 12 weeks after receiving the
R E S E A R C H
Figure 1. The two periodontal instruments evaluated in the
study. A. Instrument 2 (weighing 34 grams with an 8-millimeter–
diameter handle).
B. Instrument 1 (weighing 14 g with an
11-mm–diameter handle).
A
B
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allocated intervention (Figure 2). We included
their data in the analysis following intent-to-
treat methods (that is, the last observation was
carried forward to the 16th week). One partici-
pant who was assigned to the heavy instrument
with the narrow-diameter handle dropped out
because the instrument was too heavy. The
other four participants who dropped out had
been assigned to the lighter instrument with
the larger diameter; one of these participants
dropped out because the instrument was not as
effective as her usual instruments, and the
other three stopped working because of personal
health issues unrelated to the study. During the
intervention period, the weekly reported mean
hours of dental procedures, hours of scaling or
root planing, and hours of use of the assigned
instrument were similar between the two inter-
vention groups (Tables 1 and 2).
(Table 3, page 1111) shows a comparison of
differences in pain score changes between the
two intervention groups from the month before
the intervention began to the last month of the
intervention. The unadjusted pain scores
improved more for participants who used
instrument 1 (light handle with wide diameter)
than for those who used instrument 2 (heavy
handle with narrow diameter) for the three
right–upper-extremity regions. After adjusting
for age, sex, occupation and hours of instrument
use per week, we found that the only significant
difference between the two groups was for
shoulder pain. The interaction terms between
instrument and sex, instrument and age, and
instrument and occupation were not significant
and, therefore, we did not include them in the
final models.
Secondary outcomes. For the secondary
outcomes, both the number of nights awakened
with finger numbness and the number of days of
pain medication use improved more for partici-
pants assigned to the lightweight instrument
R E S E A R C H
Figure 2. Flowchart of the randomized controlled trial of the effect of curette handle design on upper-extremity pain.
Enrollment
Allocation
Follow-up
Analysis
Assessed for Eligibility (n = 163)
Randomized (N = 110)
Allocated to Heavy Handle, Narrow Diameter (n = 56)
Received Allocated Intervention (n = 56)
Allocated to Light Handle, Wide Diameter (n = 54)
Received Allocated Intervention (n = 54)
Excluded (n = 53)
Did Not Meet Inclusion Criteria (n = 29)
Declined to Participate (n = 24)
Analyzed (n = 56)
Excluded From Analysis (n = 0)
Analyzed (n = 54)
Excluded From Analysis (n = 0)
Lost to Follow-up (n = 0)
Discontinued Intervention (n = 1): Instrument Too
Heavy
Lost to Follow-up (n = 0)
Discontinued Intervention (n = 4): 3 for Health
Reasons Unrelated to Study, 1 Did Not Like
Instrument
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with the wide diameter than they did for those
assigned to the heavy instrument with the
narrow diameter (Table 4, page 1112). The mean
difference between the groups with regard to
the change in number of nights that partici-
pants were awakened with numbness in the
right thumb or index or middle finger was 1.6
(95 percent confidence interval [CI], 0.13 to
2.92; P = .04). The mean difference between the
groups with regard to the change in days of pain
medication use was 0.7 (95 percent CI, 0.03 to
1.50; P = .07).
Exit survey. The online exit survey ratings
for instrument diameter, weight, shape and pro-
ductivity were more positive for participants
who used the lightweight instrument with the
wide diameter than they were for those who
used the heavy instrument with the narrow
diameter (Table 2). We noted similar findings in
participants’ responses to the open-ended ques-
tions regarding the positive and negative fea-
tures of the assigned instrument. Participants
reported that they used the assigned instru-
ment approximately 82
percent of the time
during scaling and root
planing procedures
(Table 2). One indication
of successful masking in
this study was that par-
ticipants’ positive and
negative comments about
the handle texture,
which was the same for
the two instruments,
were distributed simi-
larly between the two
intervention groups. Six-
teen participants who
used the larger-diameter
instrument reported that
the tips were loosened
easily and were not stiff
enough. These instru-
ments were made from
acetal resin, which did
not maintain a stiff
thread. Consequently, we
had to replace several of
these handles during the
study.
DISCUSSION
The mean pain scores for
the three regions
(wrist/hand, elbow/
forearm and shoulder)
improved in both intervention groups during the
four-month study. However, the improvements
were greater among those who were assigned to
the lighter instrument with the larger-diameter
handle. The differences between groups were
statistically significant for change in shoulder
pain but not for change in wrist or elbow pain.
The lack of interaction between the instrument
and the covariates (sex, age and occupation)
indicates that the reported changes in pain
scores are relatively homogeneous across
the range of covariates and that stratification
on the covariates would not have altered our
findings.
The reported difference between groups in
change in right shoulder pain from preinterven-
tion to postintervention was modest (0.33) and
represents a 16 percent decline from the mean
baseline shoulder pain score of 2.1. Although the
effect is relatively small, it is similar to that
observed in other workplace intervention
studies. Rempel and colleagues
28
found that a
new task chair design tested among garment
R E S E A R C H
Participants’ work pattern during intervention
period and exit survey results.
VARIABLE HEAVY INSTRUMENT,
NARROW HANDLE
(n = 56)
LIGHT INSTRUMENT,
WIDE HANDLE
(n = 54)
Mean (SD
*
) No. of Hours per Week
Dental procedure
25.3 (7.3) 25.3 (7.6)
Scaling or root planing
12.4 (7.8) 11.9 (6.4)
Use of assigned instrument
9.8 (4.8) 10.2 (6.4)
Mean (SD) Exit Survey Rating of
Assigned Instrument (0 = Worst;
5 = Best)
Compared with usual instrument
2.6 (1.3) 3.6 (1.4)
Diameter
2.4 (1.2) 3.9 (1.1)
Weight
2.3 (1.5) 4.3 (1.1)
Shape
2.8 (1.2) 3.9 (1.0)
Productivity
2.7 (1.1) 3.6 (1.3)
Positive Features of Assigned
Instrument According to Exit Survey
Rating,
No. of Participants
Weight
10 38
Diameter
9 19
Surface texture
13 9
Negative Features of Assigned
Instrument According to Exit Survey
Rating,
No. of Participants
Weight
28 4
Diameter
22 1
Surface texture
4 3
Tips too loose
3 16
* SD: Standard deviation.
Calculated from the weekly questionnaire completed during the intervention period.
Cumulative responses from open-ended questions on the exit survey. Not all participants
answered the question.
TABLE 2
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workers reduced shoulder and neck pain by 0.28
point on a 0- to 10-point scale. Rempel and col-
leagues
29
reported that use of a forearm support
board resulted in reduced shoulder and neck
pain among computer users by 0.48 point on the
same 0- to 10-point scale. On the basis of the
results of our previous laboratory studies, we
expected the reduction in pinch force to be
greater than 33 percent when participants used
the lighter, larger-diameter instrument com-
pared with the heavier, smaller-diameter
instrument.
In a recent prospective study of blue-collar
workers, Harris and colleagues
19
found that the
duration of work during which pinch force was
greater than 10 N was a strong predictor of
upper-extremity musculoskeletal disorders. The
smaller effect size in our RCT may be due to the
fact that participants used more instruments
than the ones provided to them for dental
hygiene procedures. We might have observed a
larger effect if all of the instruments used had
been replaced with the instrument to which par-
ticipants had been assigned.
The effect of the instrument and differences
in pinch force on the shoulder may be due to an
increase in shoulder muscle co-contraction when
the dental professional increases the hand grip
force.
30
During dental hygiene procedures, the
high-force fine motor work of the hand requires
shoulder stabilization, which is achieved by
increased shoulder muscle activity. Investiga-
tors conducting epidemiologic studies have iden-
tified forceful pinch as a risk factor for shoulder
disorders.
24,25
Our study findings show that secondary out-
come measures also improved more among par-
ticipants assigned to the lightweight wide-
diameter curettes than they did among those
assigned to the heavy, narrow-diameter
curettes. At baseline, 20 participants reported
experiencing symptoms, which may be asso-
ciated with carpal tunnel syndrome (that is,
numbness or tingling in the thumb or index or
middle finger) and they reported waking an
average of two nights per week because of these
symptoms. Among those assigned to the light-
weight, wide-diameter curette, this number
declined to 0.7 night per week, whereas in the
other group, it increased to 2.1 nights per week
(P = .04). Given the small number of partici-
pants, we did not adjust for covariates in our
analysis. The results showed no significant dif-
ference between the intervention groups with
regard to change in medication use from base-
line to postintervention.
Study strengths and limitations. The
strengths of this study were the randomized
intervention design, with randomization at the
level of the dental office (to minimize contami-
R E S E A R C H
TABLE 3
Unadjusted and adjusted* regression models comparing effects of
periodontal curette instrument on change in pain scores in right–
upper-extremity regions.
BODY REGION HEAVY INSTRUMENT,
NARROW HANDLE
(n = 56)
LIGHT INSTRUMENT,
WIDE HANDLE
(n = 54)
BETA
(95% CI
)
P VALUE
MEAN PAIN
SCORE CHANGE
§
SEM
MEAN PAIN
SCORE CHANGE
SEM
Wrist/Hand
Unadjusted
0.14 0.11 0.40 0.11 0.13 .10
Adjusted
0.14 0.17 0.40 0.18 0.11 .15
(
0.04-0.28)
Elbow/Forearm
Unadjusted
0.06 0.09 0.20 0.09 0.07 .27
Adjusted
0.06 0.14 0.20 0.15 0.07 .29
(
0.06-0.21)
Shoulder
Unadjusted
0.19 0.15 0.51 0.16 0.17 .03
Adjusted
0.19 0.16 0.52 0.17 0.18 .02
(0.02-0.324)
* Adjusted models include covariates age, sex, occupation and mean hours of instrument use per week.
The beta coefficient for instrument in the general linear model.
CI: Confidence interval.
§ A positive value is a reduction in the pain score across the intervention period.
SEM: Standard error of the mean.
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nation bias and maintain masking); participant
masking with regard to the specific features of
the instrument being evaluated; the conceal-
ment of instrument allocation from study inves-
tigators; the effective randomization of partici-
pants whose demographic characteristics were
similar; the low dropout rate; the similar
number of hours per week that participants in
both groups performed dental procedures and
their exposure to the intervention instruments;
and the intention-to-treat approach to analysis.
One limitation of the study was in restricting
the intervention to only one type of instrument
for each participant. Another limitation was the
lack of objective clinical outcome measures, such
as results of physical examinations or of nerve
conduction studies in participants. However,
adding clinical outcomes would have substan-
tially increased the expenses associated with
the study, and the more complex logistics may
have reduced the number of participants.
CONCLUSION
The results of our study show that replacing
periodontal instruments with handles that are
lighter and wider in diameter (11 mm) than a
typical handle is a low-cost intervention that
resulted in a modest reduction in arm pain
among dental practitioners who performed
dental hygiene procedures. Other workplace
changes also are likely to lead to reduced arm
pain, but these interventions have not been
evaluated in RCTs, to our knowledge. These
changes include maintaining sharp scaling tips
to reduce the applied pinch force; scheduling
patients with
heavy calculus
on different
days; and
reducing the
time during
which the prac-
titioner applies
a high pinch
force during the
workday
(allowing
adequate
recovery time
from the pinch).
Other handle
designs, such as
a tapered grip or
high friction sur-
face, may reduce
applied pinch
force during
dental hygiene procedures, but, to our knowl-
edge, these also have not been tested in field
studies.
Disclosure. The authors did not report any disclosures.
This work was supported in part by grant R01-OH008892 from the
National Institute for Occupational Safety and Health, Centers for
Disease Control and Prevention, Atlanta.
1. Milerad E, Ekenvall L. Symptoms of the neck and upper extrem-
ities in dentists. Scand J Work Environ Health 1990;16(2):129-134.
2. Osborn JB, Newell KJ, Rudney JD, Stoltenberg JL. Musculo-
skeletal pain among Minnesota dental hygienists. J Dent Hyg 1990;
64(3):132-138.
3. Oberg T, Oberg U. Musculoskeletal complaints in dental
hygiene: a survey study from a Swedish county (published correction
appears in J Dent Hyg 1993;67[6]:288). J Dent Hyg 1993;67(5):257-
261.
4. Liss GM, Jesin E, Kusiak RA, White P. Musculoskeletal prob-
lems among Ontario dental hygienists. Am J Ind Med 1998;28(4):
521-540.
5. Finsen L, Christensen H, Bakke M. Musculoskeletal disorders
among dentists and variation in dental work. Appl Ergon
1998;29(2):119-125.
6. Akesson I, Johnsson B, Rylander L, Moritz U, Skerfving S.
Musculoskeletal disorders among female dental personnel: clinical
examination and a 5-year follow-up study of symptoms. Int Arch
Occup Environ Health 1999;72(6):395-403.
7. Lalumandier JA, McPhee SD. Prevalence and risk factors of
hand problems and carpal tunnel syndrome among dental hygien-
ists. J Dent Hyg 2001;75(2):130-134.
8. Werner RA, Hamann C, Franzblau A, Rodgers PA. Prevalence of
carpal tunnel syndrome and upper extremity tendinitis among
dental hygienists. J Dent Hyg 2002;76(2):126-132.
9. Crawford L, Gutierrez G, Harber P. Work environment and occu-
pational health of dental hygienists: a qualitative assessment.
J Occup Environ Med 2005;47(6):623-632.
10. Ayers KM, Thomson WM, Newton JT, Morgaine KC, Rich AM.
Self-reported occupational health of general dental practitioners
(published online ahead of print Feb. 17, 2009). Occup Med (Lond)
2009;59(3):142-148. doi:10.1093/occmed/kqp004.
11. Morse T, Bruneau H, Dussetschleger J. Musculoskeletal disor-
ders of the neck and shoulder in the dental professions. Work 2010;
35(4):419-429.
12. American Dental Association. 1997 Survey of Current Issues in
Dentistry: Repetitive Motion Injuries. Chicago: American Dental
R E S E A R C H
TABLE 4
Summary measures for participants who reported right-
finger numbness or use of medications for right–upper-
extremity pain.
SECONDARY OUTCOME MEAN (STANDARD DEVIATION)
P
VALUE
Heavy Instrument,
Narrow Handle
Light Instrument,
Wide Handle
Mean No. of Nights per Week Awakened
Because of Numbness in Fingers
(n = 9) (n = 11)
Preintervention
*
1.9 (2.1) 2.0 (2.3)
Postintervention
*
2.1 (2.7) 0.7 (1.1)
Preintervention minus postintervention
0.3 (1.0) 1.3 (1.9) .04
Mean No. of Days of Medication Use
for Upper-Extremity Pain
(n = 13) (n = 15)
Preintervention
*
1.5 (2.2) 1.1 (1.4)
Postintervention
*
1.7 (2.7) 0.6 (1.0)
Preintervention minus postintervention
0.2 (1.3) 0.5 (0.7) .07
* Calculated from weekly questionnaire during the four-week preintervention period.
Mean preintervention value minus mean postintervention value. Positive values indicate a reduction in finger
numbness or medication use after the intervention.
Copyright © 2012 American Dental Association. All rights reserved.
on October 1, 2012jada.ada.orgDownloaded from
JADA 143(10) http://jada.ada.org October 2012 1113
Association; 1997:2-8.
13. Burke FJ, Main JR, Freeman R. The practice of dentistry: an
assessment of reasons for premature retirement. Br Dent J
1997;182(7):250-254.
14. Hamann C, Werner RA, Franzblau A, Rodgers PA, Siew C,
Gruninger S. Prevalence of carpal tunnel syndrome and median
mononeuropathy among dentists. JADA 2001;132(2):163-170.
15. Anton D, Rosecrance J, Merlino L, Cook T. Prevalence of
musculoskeletal symptoms and carpal tunnel syndrome among
dental hygienists. Am J Ind Med 2002;42(3):248-257.
16. Leigh JP, Miller TR. Occupational illnesses within two national
data sets. Int J Occup Environ Health 1998;4(2):99-113.
17. Geoghegan JM, Clark DI, Bainbridge LC, Smith C, Hubbard R.
Risk factors in carpal tunnel syndrome. J Hand Surg Br 2004;29(4):
315-320.
18. Bernard BP, Putz-Anderson V. Musculoskeletal Disorders and
Workplace Factors: A Critical Review of Epidemiologic Evidence for
Work-related Musculoskeletal Disorders of the Neck, Upper
Extremity, and Low Back. Atlanta: U.S. Department of Health and
Human Services, Public Health Service, Centers for Disease Control
and Prevention, National Institute for Occupational Safety and
Health; 1997. DHHS publication (NIOSH) 97-141.
19. Harris C, Eisen E, Goldberg R, et al. 1st place, PREMUS best
paper competition: workplace and individual factors in wrist tendi-
nosis among blue-collar workers—the San Francisco study (pub-
lished online ahead of print Feb. 6, 2011). Scand J Work Environ
Health 2011;37(2):86-98. doi:10.5271/sjweh.3147.
20. Rice VJ, Nindl B, Pentikis JS. Dental workers, musculoskeletal
cumulative trauma, and carpal tunnel syndrome, who is at risk? A
pilot study. Int J Occup Saf Ergon 1996;2(3):218-233.
21. Bramson JB, Smith S, Romagnoli G. Evaluating dental office
ergonomic risk factors and hazards. JADA 1998;129(2):174-183.
22. Dong H, Loomer P, Villanueva A, Rempel D. Pinch forces and
instrument tip forces during periodontal scaling. J Periodontol
2007;78(1):97-103.
23. Roquelaure Y, Mechali S, Dano C, et al. Occupational and per-
sonal risk factors for carpal tunnel syndrome in industrial workers.
Scand J Work Environ Health 1997;23(5):364-369.
24. Silverstein BA, Bao SS, Fan ZJ, et al. Rotator cuff syndrome:
personal, work-related psychosocial and physical load factors. J
Occup Environ Med 2008;50(9):1062-1076.
25. van Rijn RM, Huisstede BM, Koes BW, Burdorf A. Associations
between work-related factors and specific disorders of the shoulder: a
systematic review of the literature (published online ahead of print
Jan. 22, 2010). Scand J Work Environ Health 2010;36(3):189-201.
doi:10.5271/sjweh.2895.
26. Dong H, Barr A, Loomer P, Laroche C, Young E, Rempel D. The
effects of periodontal instrument handle design on hand muscle load
and pinch force. JADA 2006;137(8):1123-1130.
27. Ozawa T, Nakano M, Sugimura H, et al. Effects of endodontic
instrument handle diameter on electromyographic activity of
forearm and hand muscles. Int Endod J 2001;34(2):100-106.
28. Rempel DM, Wang PC, Janowitz I, Harrison RJ, Yu F, Ritz BR.
A randomized controlled trial evaluating the effects of new task
chairs on shoulder and neck pain among sewing machine operators:
the Los Angeles garment study. Spine 2007;32(9):931-938.
29. Rempel DM, Krause N, Goldberg R, Benner D, Hudes M,
Goldner GU. A randomized controlled trial evaluating the effects of
two workstation interventions on upper body pain and incident
musculoskeletal disorders among computer operators. Occup Env-
iron Med 2006;63(5):300-306.
30. Sporrong H, Palmerud G, Herberts P. Hand grip increases
shoulder muscle activity: an EMG analysis with static hand contrac-
tions in 9 subjects. Acta Orthop Scand 1996;67(5):485-490.
R E S E A R C H
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on October 1, 2012jada.ada.orgDownloaded from
    • "The literature is in agreement that hand-pieces of diameter between 6 and 8 mm require considerable muscular strength to control their function, such that prolonged use may lead to overloading the extrinsic and intrinsic muscles and tendons of the hand [10,14,15,21,22,26] and that those of greater diameter may restrict access to the posterior regions of the patient's oral cavity [20] but they seem to be most effective in reducing fatigue [26]. It is also generally accepted that hand-pieces should preferably have knurled or grooved finish, or be coated with anti-slip material (as they require a lighter grip) and offer an adequate area of contact with the hand to avoid excessive localized pressure [21,22,24] . "
    Full-text · Article · Jan 2014
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    Conference Paper · Jun 2014 · Open Journal of Stomatology
  • [Show abstract] [Hide abstract] ABSTRACT: This discussion panel aims to identify ergonomic concerns, solutions and research needs, physical stresses, and outcomes related to clinical and surgical procedures. This session will begin with formal presentations to demonstrate current ergonomic concerns and research initiatives associated with clinical and surgical procedures to frame the panel discussion for the second part of the session. Discussion of different procedures will help to identify solutions and research needs that relate to a broad range of ergonomic problems. Questions will be collected from the attendees and speakers and organized so as to guide the panel discussion and to engage all of the speakers in the discussion to achieve the symposium aims.
    Article · Oct 2014
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