- Email: [email protected]
Repeatability of a specially designed intraoral colorimeter
THEJOURNALOFPROSTHETICDENTISTRY
HANSASUTAETAL
15. Assmussen E. Factor affecting the quantity of remaining double bonds in restorative resin polymer. Stand J Dent Res 1982;90:490-6. 16. Tirtha R, Fan PL, Powers JM. In vitro depth of cure of photoactivated composites. J Dent Res 1982;61:1184-7. 17. Hanks CT, Strawn SE, Wataha JC, Craig RG. Cytotoxic effects of resin components on cultured mammalian fibroblasts. J Dent Res 1991;70:1450-5. 18. Terakado M, Yamaxaki M, Tsujimoto Y, et al. Lipid peroxidation as a possible cause of benzoyl peroxide toxicity in rabbit dental pulp-a microsomal lipid peroxidation in vitro. J Dent Res 1984;63:901-5. 19. Fujisawa S, Kadoma Y, Komoda Y. ‘Hand 13C NMR studies of the interaction of eugenol, phenol and triethyleneglycol dimethacrylate with phospholipid liposomes as a model system for odontoblast membranes. J Dent Res 1988;67:1438-41. 20. Ferracane JL, Greener EH. The effect of resin formulation on the de-
Repeatability
of a specially
Gary R. Goldstein, New
York
University,
of Dentistry,
New
York,
Reprint
requests
to:
DR. ROBERT E. COHEN UB SCHOOL OF DENTAL 250 SQUIRE HALL BUFFALO, NY 14214
designed
DDS,a and George W. Schmitt, College
gree of conversion and mechanical properties of dental restorative resins. J Biomed Mater Res 1986;20:121-31. 21. Ruyter IE, Svendsen SA. Remaining methacrylate groups in composite restorative materials. Acta Odontol Stand 1978;36:75-82. 22. Leung RL, Fan PL, Johnston WM. Post-irradiation polymerization of visible light-activated composite resin. J Dent Res 1983;62:363-5. 23. Cataldo E, Santis H. Response of the oral tissue to exogenous foreign materials. J Periodontol 1974;45:93-106.
MEDICINE
intraoral
calorimeter
DDSb
N. Y.
A specially modified Minolta CS-100 calorimeter with a DP-101 data processor was designed for intraoral use. To test the repeatability of the results obtained with this specially modified unit, five porcelain and five acrylic resin denture teeth were mounted in a fixed position in front of a fixed mounted meter. Three L*a*b* readings were taken per tooth and mean values were obtained after calibration as a baseline measurement. The readings were repeated on day 3 without recalibration and on day 8 after recalibration. The same-day repeatability showed AE values <0.4 in nine of the 10 samples. The day 3 repeatability showed AE values <0.4 in only 2 of the 10 samples. The day 8 results, after recalibration, showed AE values >0.4 in all of the samples, with a range of 0.57 to 2.75. In vivo testing was performed on five patients with AE values that ranged from 1.1 to 32.1. (J PROSTHET D~~~1993;69:616-9.)
M
atching tooth shades intraorally has been both empirical and subjective. Colorimeters have been produced, but the most reliable are contact types, which cannot be disinfected or sterilized. In an effort to overcome this problem, a noncontact calorimeter was modified with a powerful light source for possible use in the oral environment. This study tested the repeatability of the results obtained with this specially designed calorimeter. MATERIAL
AND
1). A Sumita SLS-100 LSE (Sumita Optical Glass Mfg. Co., Tokyo, Japan) light source (Fig. 2), which uses a quartz halogen bulb (3100” K), was connected by fiberoptic cables, through LB200 color temperature conversion filters, to
METHODS
A specially modified Minolta CS-100 calorimeter with a DP-101 data processor (Minolta Corp., Industrial Meter Division, Ramsey, N. J.) was designed for intraoral use (Fig. Presented at the American Association for ton, Mass. aProfessor and Director of Prosthodontic Restorative Dentistry and Prosthodontic bAssistant Professor and Assistant Director tures, Division of Restorative Dentistry ences. Copyright @ 1993 by The Editorial Council PROSTHETIC DENTISTRY. 0022-3913/93/$1.00 + .lO.
616
10/l/46149
Dental
Research,
Bos-
Research, Division of Sciences. for Complete Denand Prosthodontic Sciof the THE JOURNAL
OF
Fig. 1. Specially modified CS-100 meter fixed in position and aimed at fixed mounted calibration card. VOLUME
69
NIJMRER
6
GOLDSTEIN
Fig.
DP-101
Table
AND
SCHMITT
2. Sumita SLS-100 data processor.
Acrylic
I.
LSE
light
source
and Minolta
Fig. 3. Fixed denture
resin denture
Day
102
112
118
mounted
meter
OF PROS’WETiC
aimed
DENTISTRY
:i: tixed
mounted
teeth
Shade
108
JOURNAL
tooth.
Mean
104
THE
values
obtained
L*
a*
b*
1 3 8 1 3 8 1 3 8
69.27 68.54 68.54 69.76 69.65 69.41 67.09 66.69 66.73
+1.40 +1.33 +0.91 -0.76 -0.54 -0.92 t1.01 +0.62 +0.26
+14.57 +14.31 +14.18+ +16.39 +16.50 +15.97 +20.04 +19.35 +1s.75
1 :i 8
69.01 68.45 68.19
-0.29 -0.31 -0.29
+19.3:1 +19.5:-I +19.34
1 3 8
66.47 66.53 66.55
t1.35 t1.25 +0.46
+25.32 +25.61 +25.01
AE
0.778” 1.031** $1 < no* 0.5f;9* * 0.997:” 1.Gl** 0.590” ‘)-. 'i&17" *
_--_-
o.xIo* 0.946'* ~-. _.--.--.--___
*AE for day 3 compared with day 1. **AE for day 8 compared with day 1.
project two beams of 7100° K light at a 45 degree angle to a fixed point. The distance from the source to the target was fixed at 50 mm. A Minolta 110 close-up lens, with a 1.3 mm measuring diameter, was attached to the front of the CS100 meter. To test the repeatability of this specially modified unit, five porcelain denture teeth-Trubyte Bioform B62, B65, B69, B77, and B81-and five acrylic resin denture teethTrubyte Bioblend 102, 104, 108, 112, and 118-(Densply International, York, Penn.) were mounted in a fixed position in front of the fixed mounted meter (Fig. 3). The anterior teeth were divided into ninths by establishment vertically of an incisal, middle, and gingival third, and horizontally a mesial, middle, and distal third. All data were obtained from readings taken in the middle of the JUNE
1993
middle third, because this is the flattest portion of a tooth. After calibration with a fixed calibration card, three L*a*b* readings per tooth were taken and mean values were calculated for a baseline measurement. The readings were repeated on day 3 without recalibration and on day 8 after recalibration. In vivo testing was performed on the maxillary right central incisor in five patients. The unit was hand held and three readings were taken in each of the incisal, middle, and gingival thirds of the mesiodistal middle third of the teeth.
RESULTS Table I (acrylic resin denture teeth) and Table II (porcelain denture teeth) show the mean values obtained from 617
THE
JOURNAL
Table
OF PROSTHETIC
DENTISTRY
GOLDSTEIN
AND
SCHMITT
Porcelain denture teeth
II.
Mean Shade
Day
B62
1 3 8 1 3 8 1 3 8 1 3 8 1 3 8
B65
B69
B77
B81
L*
a*
67.68 65.10 67.41 66.15 63.82 66.22 62.20 61.22 61.20 63.27 61.16 62.96 61.99 59.00 61.17
-0.37 +0.20 -0.25 +1.14 +0.78 +1.44 +0.26 +O.lS -0.01
values
obtained b*
+0.56 -0.07 +0.29 +1.38 +1.79 +1.57
BE
+16.16 +14.45 +15.24 +18.80 +18.13 +16.33 +17.90 +16.66 +17.35 +19.87 +20.31 +21.09 +23.63 +22.08 +22.79
3.140* 0.966** 2.45* 2.49** 1.26* 1.67** 2.15* 1.26** 3.39* 1.19**
*AE for day 3 compared with day 1. **AE for day 8 compared with day 1.
Table
III.
In vivo trials
Patient
AL*
1
I M G I
2
M G I M G I M G I M G
3
4
5
I, In&al;
M, middle;
da*
Ab*
AE
4.0 2.7 4.0
0.009 0.006 0.002
0.008 0.006 0.011
4.0 2.7 4.0
22.8 32.1 7.6 4.8 3.5 4.0 4.7 18.9 25.0 2.0 1.1 2.7
0.026 0.008 0.000 0.009 0.008 0.008 0.003 0.017 0.025 0.007 0.004 0.007
0.019 0.032 0.004 0.002 0.010 0.004 0.012 0.007 0.022 0.003 0.003 0.009
22.8 32.1 7.6 4.8 3.5 4.0 4.7 18.9 25.0 2.0 1.1 2.7
G, gingival.
the three readings taken on day 1, day 3 (without recalibration), and day 8 (after recalibration). The AE values were calculated to compare day 3 with day 1 and day 8 with day 1. The day 3 to day 1 comparison showed AE values (0.4 in only two of the 10 samples. The day 8 (after recalibration) to day 1 comparison showed AE values >0.4 in all of the samples, with a range of 0.57 to 2.75. The AE values of the porcelain denture teeth were greater than those of the acrylic resin denture teeth, with the most variation in the L* readings. Clinical trials were conducted with the unit hand held. Table III (in vivo trials) shows the change or differences in L*, a*, and b* between the three readings taken. The AE
was calculated to show the difference between the three readings, with values ranging from 1.1 to 32.1.
DISCUSSION It is desirable for the investigator-clinician to be able to repeat results under ideal conditions when using a scientific instrument whose purpose is to quantitate change. If the standard error of the unit is so large that it indicates a color change when no color change exists, the instrument is not acceptable as a research tool. The highly trained human eye can detect color changes when AE is greater than 0.4. It is derived from the formula: AE = \/(AL*)2
+ (Aa*)’
+ (Ab*)2.
GOLDSTEIN
AND
THE
SCHMITT
Clinically discernable SE values are debatable,1-3 but the results obtained with the unit could not be adequately repeated. The results of the in vitro testing were discouraging because the denture teeth were mounted in a fixed position and light readings were taken on the flattest portion of the tooth. Same-day repeatability tests were run with the position of the fiberoptic cord altered, with the overhead lights on and off, in the morning when the room was hot, and after air-conditioning had cooled the environment. All variables affect,ed the repeatability of the light meter. In the clinical trials, the range of AE values was 1.1 to 32.1, wit,h all of the major changes taking place in the L* readings. Minor movement of the patient and/or operator meant that the measurements were not being taken at exactly the same position on the tooth. Variations in texture and surface contour, translucency, and subsurface stains all affect the way the light is reflected to the meter. Trying to get repeatable readings in areas where the tooth was not flat, for example, mesiogingival and distogingival thirds of the tooth, was nearly impossible. Plaque and saliva caused major variations in L*a*b* readings. The unit was bulky and difficult to stabilize, and the fiberoptic cords prevented easy access to the meter’s control panel.
Bound
volumes
available
JOIJRWAL
OP PKOST?iETI(
DE.h’TISTRY
CONCLUSIONS A specially modified calorimeter was ineffective in producing repeatable readings of tooth color. The unit was bulky and difficult to position when hand held for in vivo work. Even when it was mounted in a nxed position and recalibrated before each use, it was unreliable and sensitive to changes in the fiberoptic cord, ambient light. and room temperature. REFERENCES 1. O’Brien equation 2. Johnston servation 3. Wozniak tal shade
WJ, (;I*oh CL, Boenke KM. A new, small-color-difference for dental shades. J Dent Res 1990$9:1762-4. WM, Kao EC. Assessment of appearance match hy visual ohand clinical calorimetry. J Dent Res 1989:6B:819-12. WT. Plroposed guidelines for the accepiance program for denguides. Chicago, Ill: Am Dent Assoc. l!%V:l 2.
to subscribers
Bound volumes of THE JOURNALOFPROSTHETICDENTISTRY are available to subscribers (only) for the 1993 issues from the publisher at a cost of $60.56 ($73.50 international) for Vol. 69 (January-June) and Vol. 70 (July-December). Shipping charges are included. Each bound volume contains a subject and author index, and all advertising is removed. Copies are shipped within 30 days after publication of the last issue in the volume. The binding is durable buckram with the journal name, volume number, and year stamped in gold on the spine. Volumes 67 and 68 are also available. Payment must accompany all orders. Contact Mosby, Subscription Services, 11830 Westline Industrial Drive, St. Louis, MC 63146-3318, USA; phone (800) 3254177, ext. 4351, or (314)453-4351. Subscriptions must be in force to qualify. in place of a regular JOURNAL subscription.
JUNE
1993
Bound
volumes
are not available
619
HANSASUTAETAL
15. Assmussen E. Factor affecting the quantity of remaining double bonds in restorative resin polymer. Stand J Dent Res 1982;90:490-6. 16. Tirtha R, Fan PL, Powers JM. In vitro depth of cure of photoactivated composites. J Dent Res 1982;61:1184-7. 17. Hanks CT, Strawn SE, Wataha JC, Craig RG. Cytotoxic effects of resin components on cultured mammalian fibroblasts. J Dent Res 1991;70:1450-5. 18. Terakado M, Yamaxaki M, Tsujimoto Y, et al. Lipid peroxidation as a possible cause of benzoyl peroxide toxicity in rabbit dental pulp-a microsomal lipid peroxidation in vitro. J Dent Res 1984;63:901-5. 19. Fujisawa S, Kadoma Y, Komoda Y. ‘Hand 13C NMR studies of the interaction of eugenol, phenol and triethyleneglycol dimethacrylate with phospholipid liposomes as a model system for odontoblast membranes. J Dent Res 1988;67:1438-41. 20. Ferracane JL, Greener EH. The effect of resin formulation on the de-
Repeatability
of a specially
Gary R. Goldstein, New
York
University,
of Dentistry,
New
York,
Reprint
requests
to:
DR. ROBERT E. COHEN UB SCHOOL OF DENTAL 250 SQUIRE HALL BUFFALO, NY 14214
designed
DDS,a and George W. Schmitt, College
gree of conversion and mechanical properties of dental restorative resins. J Biomed Mater Res 1986;20:121-31. 21. Ruyter IE, Svendsen SA. Remaining methacrylate groups in composite restorative materials. Acta Odontol Stand 1978;36:75-82. 22. Leung RL, Fan PL, Johnston WM. Post-irradiation polymerization of visible light-activated composite resin. J Dent Res 1983;62:363-5. 23. Cataldo E, Santis H. Response of the oral tissue to exogenous foreign materials. J Periodontol 1974;45:93-106.
MEDICINE
intraoral
calorimeter
DDSb
N. Y.
A specially modified Minolta CS-100 calorimeter with a DP-101 data processor was designed for intraoral use. To test the repeatability of the results obtained with this specially modified unit, five porcelain and five acrylic resin denture teeth were mounted in a fixed position in front of a fixed mounted meter. Three L*a*b* readings were taken per tooth and mean values were obtained after calibration as a baseline measurement. The readings were repeated on day 3 without recalibration and on day 8 after recalibration. The same-day repeatability showed AE values <0.4 in nine of the 10 samples. The day 3 repeatability showed AE values <0.4 in only 2 of the 10 samples. The day 8 results, after recalibration, showed AE values >0.4 in all of the samples, with a range of 0.57 to 2.75. In vivo testing was performed on five patients with AE values that ranged from 1.1 to 32.1. (J PROSTHET D~~~1993;69:616-9.)
M
atching tooth shades intraorally has been both empirical and subjective. Colorimeters have been produced, but the most reliable are contact types, which cannot be disinfected or sterilized. In an effort to overcome this problem, a noncontact calorimeter was modified with a powerful light source for possible use in the oral environment. This study tested the repeatability of the results obtained with this specially designed calorimeter. MATERIAL
AND
1). A Sumita SLS-100 LSE (Sumita Optical Glass Mfg. Co., Tokyo, Japan) light source (Fig. 2), which uses a quartz halogen bulb (3100” K), was connected by fiberoptic cables, through LB200 color temperature conversion filters, to
METHODS
A specially modified Minolta CS-100 calorimeter with a DP-101 data processor (Minolta Corp., Industrial Meter Division, Ramsey, N. J.) was designed for intraoral use (Fig. Presented at the American Association for ton, Mass. aProfessor and Director of Prosthodontic Restorative Dentistry and Prosthodontic bAssistant Professor and Assistant Director tures, Division of Restorative Dentistry ences. Copyright @ 1993 by The Editorial Council PROSTHETIC DENTISTRY. 0022-3913/93/$1.00 + .lO.
616
10/l/46149
Dental
Research,
Bos-
Research, Division of Sciences. for Complete Denand Prosthodontic Sciof the THE JOURNAL
OF
Fig. 1. Specially modified CS-100 meter fixed in position and aimed at fixed mounted calibration card. VOLUME
69
NIJMRER
6
GOLDSTEIN
Fig.
DP-101
Table
AND
SCHMITT
2. Sumita SLS-100 data processor.
Acrylic
I.
LSE
light
source
and Minolta
Fig. 3. Fixed denture
resin denture
Day
102
112
118
mounted
meter
OF PROS’WETiC
aimed
DENTISTRY
:i: tixed
mounted
teeth
Shade
108
JOURNAL
tooth.
Mean
104
THE
values
obtained
L*
a*
b*
1 3 8 1 3 8 1 3 8
69.27 68.54 68.54 69.76 69.65 69.41 67.09 66.69 66.73
+1.40 +1.33 +0.91 -0.76 -0.54 -0.92 t1.01 +0.62 +0.26
+14.57 +14.31 +14.18+ +16.39 +16.50 +15.97 +20.04 +19.35 +1s.75
1 :i 8
69.01 68.45 68.19
-0.29 -0.31 -0.29
+19.3:1 +19.5:-I +19.34
1 3 8
66.47 66.53 66.55
t1.35 t1.25 +0.46
+25.32 +25.61 +25.01
AE
0.778” 1.031** $1 < no* 0.5f;9* * 0.997:” 1.Gl** 0.590” ‘)-. 'i&17" *
_--_-
o.xIo* 0.946'* ~-. _.--.--.--___
*AE for day 3 compared with day 1. **AE for day 8 compared with day 1.
project two beams of 7100° K light at a 45 degree angle to a fixed point. The distance from the source to the target was fixed at 50 mm. A Minolta 110 close-up lens, with a 1.3 mm measuring diameter, was attached to the front of the CS100 meter. To test the repeatability of this specially modified unit, five porcelain denture teeth-Trubyte Bioform B62, B65, B69, B77, and B81-and five acrylic resin denture teethTrubyte Bioblend 102, 104, 108, 112, and 118-(Densply International, York, Penn.) were mounted in a fixed position in front of the fixed mounted meter (Fig. 3). The anterior teeth were divided into ninths by establishment vertically of an incisal, middle, and gingival third, and horizontally a mesial, middle, and distal third. All data were obtained from readings taken in the middle of the JUNE
1993
middle third, because this is the flattest portion of a tooth. After calibration with a fixed calibration card, three L*a*b* readings per tooth were taken and mean values were calculated for a baseline measurement. The readings were repeated on day 3 without recalibration and on day 8 after recalibration. In vivo testing was performed on the maxillary right central incisor in five patients. The unit was hand held and three readings were taken in each of the incisal, middle, and gingival thirds of the mesiodistal middle third of the teeth.
RESULTS Table I (acrylic resin denture teeth) and Table II (porcelain denture teeth) show the mean values obtained from 617
THE
JOURNAL
Table
OF PROSTHETIC
DENTISTRY
GOLDSTEIN
AND
SCHMITT
Porcelain denture teeth
II.
Mean Shade
Day
B62
1 3 8 1 3 8 1 3 8 1 3 8 1 3 8
B65
B69
B77
B81
L*
a*
67.68 65.10 67.41 66.15 63.82 66.22 62.20 61.22 61.20 63.27 61.16 62.96 61.99 59.00 61.17
-0.37 +0.20 -0.25 +1.14 +0.78 +1.44 +0.26 +O.lS -0.01
values
obtained b*
+0.56 -0.07 +0.29 +1.38 +1.79 +1.57
BE
+16.16 +14.45 +15.24 +18.80 +18.13 +16.33 +17.90 +16.66 +17.35 +19.87 +20.31 +21.09 +23.63 +22.08 +22.79
3.140* 0.966** 2.45* 2.49** 1.26* 1.67** 2.15* 1.26** 3.39* 1.19**
*AE for day 3 compared with day 1. **AE for day 8 compared with day 1.
Table
III.
In vivo trials
Patient
AL*
1
I M G I
2
M G I M G I M G I M G
3
4
5
I, In&al;
M, middle;
da*
Ab*
AE
4.0 2.7 4.0
0.009 0.006 0.002
0.008 0.006 0.011
4.0 2.7 4.0
22.8 32.1 7.6 4.8 3.5 4.0 4.7 18.9 25.0 2.0 1.1 2.7
0.026 0.008 0.000 0.009 0.008 0.008 0.003 0.017 0.025 0.007 0.004 0.007
0.019 0.032 0.004 0.002 0.010 0.004 0.012 0.007 0.022 0.003 0.003 0.009
22.8 32.1 7.6 4.8 3.5 4.0 4.7 18.9 25.0 2.0 1.1 2.7
G, gingival.
the three readings taken on day 1, day 3 (without recalibration), and day 8 (after recalibration). The AE values were calculated to compare day 3 with day 1 and day 8 with day 1. The day 3 to day 1 comparison showed AE values (0.4 in only two of the 10 samples. The day 8 (after recalibration) to day 1 comparison showed AE values >0.4 in all of the samples, with a range of 0.57 to 2.75. The AE values of the porcelain denture teeth were greater than those of the acrylic resin denture teeth, with the most variation in the L* readings. Clinical trials were conducted with the unit hand held. Table III (in vivo trials) shows the change or differences in L*, a*, and b* between the three readings taken. The AE
was calculated to show the difference between the three readings, with values ranging from 1.1 to 32.1.
DISCUSSION It is desirable for the investigator-clinician to be able to repeat results under ideal conditions when using a scientific instrument whose purpose is to quantitate change. If the standard error of the unit is so large that it indicates a color change when no color change exists, the instrument is not acceptable as a research tool. The highly trained human eye can detect color changes when AE is greater than 0.4. It is derived from the formula: AE = \/(AL*)2
+ (Aa*)’
+ (Ab*)2.
GOLDSTEIN
AND
THE
SCHMITT
Clinically discernable SE values are debatable,1-3 but the results obtained with the unit could not be adequately repeated. The results of the in vitro testing were discouraging because the denture teeth were mounted in a fixed position and light readings were taken on the flattest portion of the tooth. Same-day repeatability tests were run with the position of the fiberoptic cord altered, with the overhead lights on and off, in the morning when the room was hot, and after air-conditioning had cooled the environment. All variables affect,ed the repeatability of the light meter. In the clinical trials, the range of AE values was 1.1 to 32.1, wit,h all of the major changes taking place in the L* readings. Minor movement of the patient and/or operator meant that the measurements were not being taken at exactly the same position on the tooth. Variations in texture and surface contour, translucency, and subsurface stains all affect the way the light is reflected to the meter. Trying to get repeatable readings in areas where the tooth was not flat, for example, mesiogingival and distogingival thirds of the tooth, was nearly impossible. Plaque and saliva caused major variations in L*a*b* readings. The unit was bulky and difficult to stabilize, and the fiberoptic cords prevented easy access to the meter’s control panel.
Bound
volumes
available
JOIJRWAL
OP PKOST?iETI(
DE.h’TISTRY
CONCLUSIONS A specially modified calorimeter was ineffective in producing repeatable readings of tooth color. The unit was bulky and difficult to position when hand held for in vivo work. Even when it was mounted in a nxed position and recalibrated before each use, it was unreliable and sensitive to changes in the fiberoptic cord, ambient light. and room temperature. REFERENCES 1. O’Brien equation 2. Johnston servation 3. Wozniak tal shade
WJ, (;I*oh CL, Boenke KM. A new, small-color-difference for dental shades. J Dent Res 1990$9:1762-4. WM, Kao EC. Assessment of appearance match hy visual ohand clinical calorimetry. J Dent Res 1989:6B:819-12. WT. Plroposed guidelines for the accepiance program for denguides. Chicago, Ill: Am Dent Assoc. l!%V:l 2.
to subscribers
Bound volumes of THE JOURNALOFPROSTHETICDENTISTRY are available to subscribers (only) for the 1993 issues from the publisher at a cost of $60.56 ($73.50 international) for Vol. 69 (January-June) and Vol. 70 (July-December). Shipping charges are included. Each bound volume contains a subject and author index, and all advertising is removed. Copies are shipped within 30 days after publication of the last issue in the volume. The binding is durable buckram with the journal name, volume number, and year stamped in gold on the spine. Volumes 67 and 68 are also available. Payment must accompany all orders. Contact Mosby, Subscription Services, 11830 Westline Industrial Drive, St. Louis, MC 63146-3318, USA; phone (800) 3254177, ext. 4351, or (314)453-4351. Subscriptions must be in force to qualify. in place of a regular JOURNAL subscription.
JUNE
1993
Bound
volumes
are not available
619