Chlordiazepoxide and Phenobarbital in a Model Anxiety-inducing Situation Richard
C. Pillard and Seymour
Fisher
T
HE STUDY reported here is one of several in which we evaluated the effects of benzodiazepine tranquilizer on persons in an anxiety-inducing situation--outpatient dentistry. The study had three purposes: (1) to see whether a benzodiazepine tranquilizer, chlordiazepoxide, would reduce anxiety in patients undergoing a standard dental procedure; (2) to see whether the anxiety reduction would be greater in patients predicted to be highly anxious during dental procedures as contrasted with those predicted to be minimally anxious; (3) to compare chlordiazepoxide and phenobarbital on criteria of anxiety reduction and the presence of side effects such as sedation. Our previous studies using diazepam in highly anxious dental patients suggested that it was somewhat more effective than placebo, but not greatly so.’ In the present study we added a group of patients who were not particularly anxious about dentistry, predicting that they would have essentially no antianxiety response to the medication. The design of this study was to choose 6 patients scoring high on fear of dental procedures and 6 scoring low. They were given chlordiazepoxide, phenobarbital, or placebo in a three-session repeated-measures design. The design therefore consisted of two levels of patient dental fear and three medications. METHODS Patients were selected from a pool of several hundred university students who
Patient selection.
were given a number of preliminary scale and the situational the situational
anxiety
screening measures. These included the Taylor
manifest anxiety
anxiety scale. which is described in greater detail below. One of the factors on scale reflects a fear of dental procedures.
Six subjects scoring in the highest
10% and 6 from the lowest 10% on the “dental phobic” factor were invited to participate
Procedure. Dentistry
The I2 volunteers
Outpatient
procedure
were asked to come to the Boston University
Clinic for three weekly sessions of tooth cleaning and scaling. This is a simple
that can normally
be accomplished
sessions of about 20 min each. Patients
in an hour, but for the study it was divided into three
were told that they would be receiving either a mild tran-
quilizer or a placebo and that the aim of the study was to help us evaluate medication.
Patients
in the study.
School of Graduate
and treating
dentists completed
various criterion
the effectiveness of the
measures before, during. and
after the cleaning procedures.
Medicorion each patient.
Chlordiazepoxide
10 mg. phenobarbital
Since there are six medicatron
30 mg, and placebo were given in sequence to
sequences, one high dental phobic and one low phobic
were assigned to each sequence. At each session five capsules were given in a coded envelope with
From Medicine.
the P.ychophormaco&y Boston.
Laboratory,
Division y/‘ Pswhiatry.
Boston
Universit:.
School
I#
Mass.
Richard C. Pillard, M.D.: .4 s?ociate ProfPssor; Seymour Fisher, Ph.D.: Profkssor: Divi.vion of P.YJ,rhiatrr. Boston University School of Medicine. This research was supported in part by NlMH grant MH 17417 and Research Screnti,st Development .4 ward MH 32896. Requests Jtir reprints ma)’ be addressed to Dr. Pillard. 80 East Concord Street. Bmton. Mass. O-71IX r? 1975 hy Grune & Stratton, Inc.
Comprehenswe
Psychiatry,
Vol. 16. No. 1 (January/Februaryl.
1975
97
98
PILLAAD AND
Table 1. Outline
of Experimental
Time (minutes)
Session Event
0
FSP #l
5
POMS #l
10
Tooth cleaning and scaling starts
20
FSP #2
25
POMS #2
30
Tooth cleaning and scaling resumes DARS Side-effects checklist PTQ Finish
40
50
FISHER
instructions to take one capsule three times daily on the day before the dental procedure, and one morning and noon on the day of the procedure, which was scheduled for early afternoon. Measures. 1. Situational
anxiety scale: This is a 28-item self-rating scale that asks the subject to rate the degree of his fear in a number of commonly feared situations. For example: How anxious would you feel if you were riding in a crowded elevator? . having a tooth pulled by a dentist? . . seeing a bloody operation?. waiting in a dentist’s office? Subjects respond to each item on a 5-point scale. Two scores were derived from this form: a dental-phobic score composed of the 5 dental items and a total-phobic score composed of the other 23 items. Since we had no previous experience with this test we did not know whether it would in fact differentiate high- from low-anxious patients in a real dental situation. 2. Taylor manifest anxiety scale (TMAS):*50 unbuffered items reflecting trait anxiety. 3. Profile of mood states (POMS)? An abbreviated and slightly modified version of this selfadministered mood-adjective rating scale was completed by the patient before and again during the procedure. Mood factors measured were tension/anxiety, fatigue/sedation, and vigor. 4. Finger sweat print (FSP): A measure of the amount of finger sweat was taken before and during the procedure at the same time as the POMS. Finger sweat produces a visible mark on treated paper, which is then rated on a l5-point scale. There is a general positive relationship between the amount of finger sweat and subjective anxiety.’ 5. Side-effects checklist: At the end of each session, the patient filled out a 22.item checklist of possible medication side effects. 6. Dentist’s anxiety rating scale (DARS): A IO-item scale on which the dentist rated each patient’s signs of anxiety, hostility, and complaints of fear or pain. 7. Post-treatment questionnaire (PTQ): At the end of each session the patient completed a short questionnaire that asked for global ratings of “discomfort,” “pain,” and “anxiety,” as well as a global estimate of how much the medication had reduced anxiety. Also, the patient was asked to judge whether he had received an active medication or placebo. Table 1 outlines the experimental sessions giving the approximate time at which each measure was administered. Before analyzing the data for medication effects, we examined it to determine whether the dental-fear items on the situational anxiety scale were a specific and valid predictor of the patient’s behavior and mood response while undergoing the dental treatment. The high and low dental phobics were, of course, different from each other on the dental-phobic items of the situational anxiety scalethat was the basis of their selection. We found that the high dental phobics were also significantly higher on the four items relating to the fear of doctors and medical procedures (p < 0.002).* There was, however, no significant difference on the other 19 items in the situational anxiety scale. Likewise, on the Taylor manifest anxiety scale, the high phobics were slightly, but not significantly, more anxious than the lows. Thus the difference between the two groups related rather specifically to their fear of dental and medical procedures and did not reflect a generalized personality trait of greater phobic concerns or enhanced anxiety.
*Based on a two-tailed t test comparing the high and low dental phobics.
CHLORDIAZEPOXIDE
AND
PHENOBARBITAL
PLACEBO CHLORDIAZEPOXIDE PHENOBARBITAL
LOW
HIGH Fig. 1. POMS tension/anxiety scores.
DENTAL PHOBICS
The validity of the dental-phobic scale (DARS)
factor was examined
and on the tension/anxiety
phobics as significantly
more anxious (p < 0.025)*
patients rated themselvevlikewise factor of the situational
by comparing
factor of the self-rated
the two groups on the dentist’s
POMS.
The dentists rated the high
during the various procedures,
as more anxious (p < O.Ol)l on the POMS.
anxiety scale does seem to accurately
and the high phobic
Therefore,
predict a patient’s
the dental
response while un-
dergoing dental treatment.
RESULTS One patient on his first clinic visit developed an episode of vasovagal syncope and lost consciousness for several seconds. He was a high dental phobic receiving chlordiazepoxide. He did not have a history of syncope, and so the exact precipitant for his episode is unclear. He was dropped from the study, leaving 5 high and 6 low dental phobics. The chief question asked by the experiment was whether the medication significantly reduced patient anxiety. Figure 1 shows POMS tension/anxiety scores. Chlordiazepoxide and phenobarbital appear to cause lower anxiety in both the high and low phobics. This tendency was not significant for chlordiazepoxide, but was significant for phenobarbital (p < O.O5).t The dentists, on their rating scale, were unable to detect any medication effects. Analysis of the finger-sweat print scores shows that neither a phobic nor a medication effect was detected on that measure. Thus, overall medication effects were detectable but small. Examination of Fig. 1 suggests that the anxiety reduction within the high phobic group is greater than within the low phobic group (as we predicted). However, the interaction term of the analysis of variance shows that this effect is not remotely significant. We conclude, therefore, that the high phobics were not differentially sensitive to medication. Figure 2 illustrates POMS scores that reflect feelings of fatigue and sedation.
*Based on a two-tailed
t test comparing
the high and low dental phobics.
tBased on a 3 x 2 analysis of variance with repeated measures on the medication test was used to compareeach
active medication
with placebo.
factor. A Dunnett
100
PILLARD AND
m
PLACEBO
;ii$;$ EJ
CHLORDIAZEPOXIDE
m
PHENOBARBITAL
FISHER
HIGH
DENTAL PHOBICS
Fig. 2. POMS fatigue scores.
Interestingly, subjects when taking chlordiazepoxide appear remarkably less sedated than when taking either placebo or phenobarbital. The overall difference between tranquilizer and placebo is significant (p < O.O5).t The complementary finding was that patients scored high on POMS vigor items while taking the tranquilizer. It appears that chlordiazepoxide had an activating or stimulating effect on these patients. Items on the side-effects checklist were examined, but no difference was found either between the high and low phobics or among the three medications. POMS and FSP tests were administered just before the cleaning procedure and again during a short break in the midst of the procedure. These two sets of tests were analyzed separately to see whether they systematically differed or whether the drugs might have a different effect before the procedure than during it. No such effects were observed. At the end of the procedure patients were asked to guess whether they had received an active medication or a placebo. They showed no significant ability to guess correctly. The errors were, for the most part, in the direction of guessing placebo when an active medication had been received. We next examined whether the high phobics were experiencing more pain during the procedures. (In a previous paper we showed that fearful patients do not give a history of experiencing greater pain.5) This information was taken from a question on the PTQ, which patients completed at the end of each session. High phobics did tend to experience more pain during the procedures (p < 0.05).* Finally, we examined the effects of habituation over the three sessions of the experiment. Separate analyses were done on the various criteria measures to determine whether, regardless of medication, the patient’s scores tended to change over time. On the POMS tension/anxiety factor, habituation was observed. Selfreported anxiety decreased monotonically over the three experimental days tBased on a 3 x 2 analysis of variance with repeated measures on the medication test was used to compare each active medication with placebo. *Based on a two-tailed
t test comparing
high and low dental phobics.
factor. A Dunnett
CHLORDIAZEPOXIDE
AND
101
PHENOBARBITAL
(p < 0.05).* Vigor, fatigue/sedation, DARS, and FSP scores showed no significant changes over time, although the vigor score did increase monotonically to an extent that was close to being significant. DISCUSSION
The hypotheses that prompted this experiment were only partially confirmed. Medication effects were detected, which was gratifying in view of the small number of subjects used, but high dental phobics did not appear especially sensitive to medication effects. Also, the high phobics appeared to be experiencing more pain during the procedures, which may in itself have prevented the active medications from having a stronger effect. This raises the possibility of whether analgesics alone or in combination with the tranquilizers would have been a more effective treatment for this group. That patients receiving medication showed no increased side effects and were not even able to detect that they were receiving active medication suggests that we might be justified in employing a larger dose. We did observe a syncopal episode in one patient for which chlordiazepoxide may have been partly responsible. The practical value of this treatment for dental outpatients would be greatly reduced if they had to endure side effects for a day prior to treatment. Nevertheless. it would appear reasonable to experiment with larger doses of chlordiazepoxide. The activating effect of the chlordiazepoxide should be noted. In previous experiments with single doses of this medication we have observed sedation.” Since no measures were taken following the first dose, it is entirely possible that patients may have been at first sedated and then stimulated. ACKNOWLEDGMENTS The authors acknowledge
the collaboration
of Dr. Morris
Ruben. Dr. Jose Priito,
and Dr. Robert
Goldman.
REFERENCES I. Fisher
S. Pillard
core anxiety drug
RC,
Yamada
in dental patients:
screening.
L: Hard-
Implications
for
Neuropsychopharmacology
measures
6:381, 1968 JA: A personality
anxiety. J Abnorm 3. McNair
DM.
Sot Psycho1 48:285. Loor
M,
Service.
19.53
Droppleman
Protile of mood states (POMS). Testing
scale of manifest
San
Diego.
1971
*Based on a two-tailed
and
Calif..
comparing
J, Atkinson
film-inducing
KW,
23:771,
anxiety.
as
Percept
1966
5. Pillard RC, Fisher S: Aspects of anxiety in 6. Pillard diazepoxide anxiety.
RC. and
Fisher
80:1331, S:
secobarbital
Psychopharmacologia
1967
t test
Carpenter
sweat prints and self-ratings
dental clinic patients. JADA LF:
Educational
RC, of
MotorSkills
2. Taylor
Industrial
4. Pillard
Fisher S: Palmar
high and low dental phobics.
1970
Effects on
of chlor-
film-induced
(Berlin)
12-18.
C. Pillard and Seymour
Fisher
T
HE STUDY reported here is one of several in which we evaluated the effects of benzodiazepine tranquilizer on persons in an anxiety-inducing situation--outpatient dentistry. The study had three purposes: (1) to see whether a benzodiazepine tranquilizer, chlordiazepoxide, would reduce anxiety in patients undergoing a standard dental procedure; (2) to see whether the anxiety reduction would be greater in patients predicted to be highly anxious during dental procedures as contrasted with those predicted to be minimally anxious; (3) to compare chlordiazepoxide and phenobarbital on criteria of anxiety reduction and the presence of side effects such as sedation. Our previous studies using diazepam in highly anxious dental patients suggested that it was somewhat more effective than placebo, but not greatly so.’ In the present study we added a group of patients who were not particularly anxious about dentistry, predicting that they would have essentially no antianxiety response to the medication. The design of this study was to choose 6 patients scoring high on fear of dental procedures and 6 scoring low. They were given chlordiazepoxide, phenobarbital, or placebo in a three-session repeated-measures design. The design therefore consisted of two levels of patient dental fear and three medications. METHODS Patients were selected from a pool of several hundred university students who
Patient selection.
were given a number of preliminary scale and the situational the situational
anxiety
screening measures. These included the Taylor
manifest anxiety
anxiety scale. which is described in greater detail below. One of the factors on scale reflects a fear of dental procedures.
Six subjects scoring in the highest
10% and 6 from the lowest 10% on the “dental phobic” factor were invited to participate
Procedure. Dentistry
The I2 volunteers
Outpatient
procedure
were asked to come to the Boston University
Clinic for three weekly sessions of tooth cleaning and scaling. This is a simple
that can normally
be accomplished
sessions of about 20 min each. Patients
in an hour, but for the study it was divided into three
were told that they would be receiving either a mild tran-
quilizer or a placebo and that the aim of the study was to help us evaluate medication.
Patients
in the study.
School of Graduate
and treating
dentists completed
various criterion
the effectiveness of the
measures before, during. and
after the cleaning procedures.
Medicorion each patient.
Chlordiazepoxide
10 mg. phenobarbital
Since there are six medicatron
30 mg, and placebo were given in sequence to
sequences, one high dental phobic and one low phobic
were assigned to each sequence. At each session five capsules were given in a coded envelope with
From Medicine.
the P.ychophormaco&y Boston.
Laboratory,
Division y/‘ Pswhiatry.
Boston
Universit:.
School
I#
Mass.
Richard C. Pillard, M.D.: .4 s?ociate ProfPssor; Seymour Fisher, Ph.D.: Profkssor: Divi.vion of P.YJ,rhiatrr. Boston University School of Medicine. This research was supported in part by NlMH grant MH 17417 and Research Screnti,st Development .4 ward MH 32896. Requests Jtir reprints ma)’ be addressed to Dr. Pillard. 80 East Concord Street. Bmton. Mass. O-71IX r? 1975 hy Grune & Stratton, Inc.
Comprehenswe
Psychiatry,
Vol. 16. No. 1 (January/Februaryl.
1975
97
98
PILLAAD AND
Table 1. Outline
of Experimental
Time (minutes)
Session Event
0
FSP #l
5
POMS #l
10
Tooth cleaning and scaling starts
20
FSP #2
25
POMS #2
30
Tooth cleaning and scaling resumes DARS Side-effects checklist PTQ Finish
40
50
FISHER
instructions to take one capsule three times daily on the day before the dental procedure, and one morning and noon on the day of the procedure, which was scheduled for early afternoon. Measures. 1. Situational
anxiety scale: This is a 28-item self-rating scale that asks the subject to rate the degree of his fear in a number of commonly feared situations. For example: How anxious would you feel if you were riding in a crowded elevator? . having a tooth pulled by a dentist? . . seeing a bloody operation?. waiting in a dentist’s office? Subjects respond to each item on a 5-point scale. Two scores were derived from this form: a dental-phobic score composed of the 5 dental items and a total-phobic score composed of the other 23 items. Since we had no previous experience with this test we did not know whether it would in fact differentiate high- from low-anxious patients in a real dental situation. 2. Taylor manifest anxiety scale (TMAS):*50 unbuffered items reflecting trait anxiety. 3. Profile of mood states (POMS)? An abbreviated and slightly modified version of this selfadministered mood-adjective rating scale was completed by the patient before and again during the procedure. Mood factors measured were tension/anxiety, fatigue/sedation, and vigor. 4. Finger sweat print (FSP): A measure of the amount of finger sweat was taken before and during the procedure at the same time as the POMS. Finger sweat produces a visible mark on treated paper, which is then rated on a l5-point scale. There is a general positive relationship between the amount of finger sweat and subjective anxiety.’ 5. Side-effects checklist: At the end of each session, the patient filled out a 22.item checklist of possible medication side effects. 6. Dentist’s anxiety rating scale (DARS): A IO-item scale on which the dentist rated each patient’s signs of anxiety, hostility, and complaints of fear or pain. 7. Post-treatment questionnaire (PTQ): At the end of each session the patient completed a short questionnaire that asked for global ratings of “discomfort,” “pain,” and “anxiety,” as well as a global estimate of how much the medication had reduced anxiety. Also, the patient was asked to judge whether he had received an active medication or placebo. Table 1 outlines the experimental sessions giving the approximate time at which each measure was administered. Before analyzing the data for medication effects, we examined it to determine whether the dental-fear items on the situational anxiety scale were a specific and valid predictor of the patient’s behavior and mood response while undergoing the dental treatment. The high and low dental phobics were, of course, different from each other on the dental-phobic items of the situational anxiety scalethat was the basis of their selection. We found that the high dental phobics were also significantly higher on the four items relating to the fear of doctors and medical procedures (p < 0.002).* There was, however, no significant difference on the other 19 items in the situational anxiety scale. Likewise, on the Taylor manifest anxiety scale, the high phobics were slightly, but not significantly, more anxious than the lows. Thus the difference between the two groups related rather specifically to their fear of dental and medical procedures and did not reflect a generalized personality trait of greater phobic concerns or enhanced anxiety.
*Based on a two-tailed t test comparing the high and low dental phobics.
CHLORDIAZEPOXIDE
AND
PHENOBARBITAL
PLACEBO CHLORDIAZEPOXIDE PHENOBARBITAL
LOW
HIGH Fig. 1. POMS tension/anxiety scores.
DENTAL PHOBICS
The validity of the dental-phobic scale (DARS)
factor was examined
and on the tension/anxiety
phobics as significantly
more anxious (p < 0.025)*
patients rated themselvevlikewise factor of the situational
by comparing
factor of the self-rated
the two groups on the dentist’s
POMS.
The dentists rated the high
during the various procedures,
as more anxious (p < O.Ol)l on the POMS.
anxiety scale does seem to accurately
and the high phobic
Therefore,
predict a patient’s
the dental
response while un-
dergoing dental treatment.
RESULTS One patient on his first clinic visit developed an episode of vasovagal syncope and lost consciousness for several seconds. He was a high dental phobic receiving chlordiazepoxide. He did not have a history of syncope, and so the exact precipitant for his episode is unclear. He was dropped from the study, leaving 5 high and 6 low dental phobics. The chief question asked by the experiment was whether the medication significantly reduced patient anxiety. Figure 1 shows POMS tension/anxiety scores. Chlordiazepoxide and phenobarbital appear to cause lower anxiety in both the high and low phobics. This tendency was not significant for chlordiazepoxide, but was significant for phenobarbital (p < O.O5).t The dentists, on their rating scale, were unable to detect any medication effects. Analysis of the finger-sweat print scores shows that neither a phobic nor a medication effect was detected on that measure. Thus, overall medication effects were detectable but small. Examination of Fig. 1 suggests that the anxiety reduction within the high phobic group is greater than within the low phobic group (as we predicted). However, the interaction term of the analysis of variance shows that this effect is not remotely significant. We conclude, therefore, that the high phobics were not differentially sensitive to medication. Figure 2 illustrates POMS scores that reflect feelings of fatigue and sedation.
*Based on a two-tailed
t test comparing
the high and low dental phobics.
tBased on a 3 x 2 analysis of variance with repeated measures on the medication test was used to compareeach
active medication
with placebo.
factor. A Dunnett
100
PILLARD AND
m
PLACEBO
;ii$;$ EJ
CHLORDIAZEPOXIDE
m
PHENOBARBITAL
FISHER
HIGH
DENTAL PHOBICS
Fig. 2. POMS fatigue scores.
Interestingly, subjects when taking chlordiazepoxide appear remarkably less sedated than when taking either placebo or phenobarbital. The overall difference between tranquilizer and placebo is significant (p < O.O5).t The complementary finding was that patients scored high on POMS vigor items while taking the tranquilizer. It appears that chlordiazepoxide had an activating or stimulating effect on these patients. Items on the side-effects checklist were examined, but no difference was found either between the high and low phobics or among the three medications. POMS and FSP tests were administered just before the cleaning procedure and again during a short break in the midst of the procedure. These two sets of tests were analyzed separately to see whether they systematically differed or whether the drugs might have a different effect before the procedure than during it. No such effects were observed. At the end of the procedure patients were asked to guess whether they had received an active medication or a placebo. They showed no significant ability to guess correctly. The errors were, for the most part, in the direction of guessing placebo when an active medication had been received. We next examined whether the high phobics were experiencing more pain during the procedures. (In a previous paper we showed that fearful patients do not give a history of experiencing greater pain.5) This information was taken from a question on the PTQ, which patients completed at the end of each session. High phobics did tend to experience more pain during the procedures (p < 0.05).* Finally, we examined the effects of habituation over the three sessions of the experiment. Separate analyses were done on the various criteria measures to determine whether, regardless of medication, the patient’s scores tended to change over time. On the POMS tension/anxiety factor, habituation was observed. Selfreported anxiety decreased monotonically over the three experimental days tBased on a 3 x 2 analysis of variance with repeated measures on the medication test was used to compare each active medication with placebo. *Based on a two-tailed
t test comparing
high and low dental phobics.
factor. A Dunnett
CHLORDIAZEPOXIDE
AND
101
PHENOBARBITAL
(p < 0.05).* Vigor, fatigue/sedation, DARS, and FSP scores showed no significant changes over time, although the vigor score did increase monotonically to an extent that was close to being significant. DISCUSSION
The hypotheses that prompted this experiment were only partially confirmed. Medication effects were detected, which was gratifying in view of the small number of subjects used, but high dental phobics did not appear especially sensitive to medication effects. Also, the high phobics appeared to be experiencing more pain during the procedures, which may in itself have prevented the active medications from having a stronger effect. This raises the possibility of whether analgesics alone or in combination with the tranquilizers would have been a more effective treatment for this group. That patients receiving medication showed no increased side effects and were not even able to detect that they were receiving active medication suggests that we might be justified in employing a larger dose. We did observe a syncopal episode in one patient for which chlordiazepoxide may have been partly responsible. The practical value of this treatment for dental outpatients would be greatly reduced if they had to endure side effects for a day prior to treatment. Nevertheless. it would appear reasonable to experiment with larger doses of chlordiazepoxide. The activating effect of the chlordiazepoxide should be noted. In previous experiments with single doses of this medication we have observed sedation.” Since no measures were taken following the first dose, it is entirely possible that patients may have been at first sedated and then stimulated. ACKNOWLEDGMENTS The authors acknowledge
the collaboration
of Dr. Morris
Ruben. Dr. Jose Priito,
and Dr. Robert
Goldman.
REFERENCES I. Fisher
S. Pillard
core anxiety drug
RC,
Yamada
in dental patients:
screening.
L: Hard-
Implications
for
Neuropsychopharmacology
measures
6:381, 1968 JA: A personality
anxiety. J Abnorm 3. McNair
DM.
Sot Psycho1 48:285. Loor
M,
Service.
19.53
Droppleman
Protile of mood states (POMS). Testing
scale of manifest
San
Diego.
1971
*Based on a two-tailed
and
Calif..
comparing
J, Atkinson
film-inducing
KW,
23:771,
anxiety.
as
Percept
1966
5. Pillard RC, Fisher S: Aspects of anxiety in 6. Pillard diazepoxide anxiety.
RC. and
Fisher
80:1331, S:
secobarbital
Psychopharmacologia
1967
t test
Carpenter
sweat prints and self-ratings
dental clinic patients. JADA LF:
Educational
RC, of
MotorSkills
2. Taylor
Industrial
4. Pillard
Fisher S: Palmar
high and low dental phobics.
1970
Effects on
of chlor-
film-induced
(Berlin)
12-18.
