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Pulpal response to four restorative materials
Section of the
Federal dental services Pulpal response to four restorative materials Xurindar N. Bhaskar, Colonel, DC, USA,” Duane E. Cutright, Lieute?bant Colollel, DC, USA,** Joe D. Beasley, Major, DC, UXA,*** and Robert C. Boyers, Lieutenant Colonel, DC, UXA”“KX UNITED
STATES
WALTER
REED
INSTITIJTE
ARMY ARMY
MEDICAL
OF DENTAL
CENTER,
RESEARCH,
WASHINGTON,
D.C.
I
n order to provide maximal dental care for patients with multiple lesions, the ideal restorative material would be one that could be inserted without elaborate cavity preparation and that could serve the patient on a semipermanent basis. The advantage of such a mat.erial lies in the fact that multiple carious lesions could be excavated a.nd restored at a single visit, with permanent restorations provided at a future date. For this purpose, two restorative materials were developed at the dental research sections of the National Bureau of Standards and the United States Army Institute of Dental Research, and a, t,hird was selected from a commercial source.‘, 2 Since, in addition to having appropriate physical properties, a restorative material must also be biologically acceptable to the dental pulp, the present study was undertaken to test the pulpal response of three experimental filling materials and one control material. METHODS .AND MATERIALS The four filling materials tested in this study were the following: No. 1 (control)-Zinc oxide and eugenol (ZOE) . No. Z-Intermediate restorative material referred to in the ensuing description as IRM. This is a commercial polymethylmethacrylate-reinforced zinc oxide-eugenol product of 1~. I). Caulk Company, Milford, Delaware. No. J-Referred to in the ensuing description as ERA, it consists of the following : *Chief, Division of Oral Pathology. **Oral Pathologist, Division of Oral Pathology. ***Resident, Division of Oral Pathology. ****Assistant Chief, Division of Oral Pathology.
126
Volume Number
28 1
Pulpal
respome to four restorative
materials
127
Powder Liquid Zinc oxide 57.0% o-Ethoxybenzoic acid 662/3% Aluminum oxide 28.0% Eugenol 33Y3% A copolymer of 9.5% methylmethac~~late Rosin 5.5% h70. 4-Referred to in the ensuing description as CA.21, it consists of the following : Powder Liquid Zinc phosphate 85.0% Isobutyl-a-cyanoacrylate Zinc oxide 15.0% monomer (sterile) The components of the experimental formulations No. 3 and No. 4 were USP and reagent grade. Three miniature pigs were anesthetized with pentosol, and Class V cavities were made with a No. 35 inverted cone bur at 150,000 r.p.m. in a total of seventyeight teeth, as shown in Table I. All cavities were prepared by the same operator, and an attempt was made to keep the cavity depths at the same level. Twentysix teeth were filled in each pig (Table I). A total of twenty-one teeth were filled with zinc oxide and eugenol, eighteen with IRM, twenty-one with EBA, and eighteen with CAZI:. In order to assure uniformity, cavity preparations, mixing of the filling materials, and insertion of t,he fillings were done by three separate operators, respectively. Animals were killed 1, 2, and 3 weeks postoperatively. Teeth were recovered with blocks of surrounding bone, the apical third was cut with rongeurs, and the specimens were fixed in 10 per cent formalin. After decalcification and paraffin embedding, sections were cut at 6 microns and stained with hematox ylin and eosin. FINDINGS
Pulps in all teeth were vital. The pulpal response to the restorative materials was measured by the degree of disruption of the oclontoblastic layer under the cavity preparation (Fig. 1) and by the number and type of inflammatory cells seen in the area (Figs. 2 and 3).3 In order to quantify the pulpal response, the degree of odontoblastic d!isruption and inflammation was graded from 0 to 4, as indicated in Table II. In addition to the odontoblastic disruption and the inflammatory cells, the pulpal response was char.scterized by the formation of new dentine (Figs. 4 to Table I. Filling materials included in the study
tested, postoperative Nuder
_Filling
material
Zinc oxide and eugenol IRM EBA Cyanoacrylate mixture Totals
1 week i 6’ 26
1
periods, and number
of teeth
teeth used
of
8 weeks
)
3 weeks
Total
7 6 7 6
21 18 21 18
7 6 i 26
s
18
128
Bhusknr
OS., O.M. & O.P. July, 1969
et ccl.
Pig. 2. Pulp from tooth ruption of odontoblasts.
which
was filld
with
ERtl
one week postoperatively.
S&e
;Lis-
Fig.
F
Pigs. d and 3. Lowone week postoperatively.
and high-power photomicrographs Noto arca of inflammation.
of pulp of tooth filled
with
CA21
6). This dentine was producetl on the pulpal wall opposite the area of the restorations and could be easily distinguished from the pre-experimental dentine by a line of demarcation, the so-called calciotraumatic line (Figs. 4 t,o 6). In addition, the newly formed dent,ine (irregular or rcpa.ratixc dentine) could be identified by the reduction in the number of its dentinal tubules and by its lighter staining qualities (Fig. 4). The pulpal response to various filling materials is given below and is summarized in Tables II and III. One
week
ZOE. In three teeth pulp showed neutrophil case was there a disruption of the odontoblastic
infiltration, and in only one layer. Irregular dentine was
Volume 28 Number 1
Pulpal
II. Average disruption four restorative materials* Table
Postoperative‘ period (weelcs)
to four
response
of odontoblasts
restorative
and inflammatory
Disruption odontoblastic
NateGal
of layer
materials
response to the InfEammatory response (l-4) 0.4 0.3 0.5 1.0
I
Zinc: oxide and eugenol IRM EBA Cyanoacrylate
0.2 0.3 it;
2
Zinc: oxide and eugenol IRJC EBA Cyanoacrylate
0.7 1.2 0.8 1.2
0.6 1.0 0.6 1.4
3
Zinc: oxide and eugenol IRSC EBA Cpanoacrylate
1.0 1.2 1.3 1.8
0.8 1.2 1.0 1.4
: Odontoblastic airruption 0 1 Layer intact 1 = Evidence of disruption 2 = Partial disruption 3 = Complete disruption 4 = Pulp ncrosis
129
*Grading
0 1 2 3 4
Ill. Average thickkness of irregular under the four filling materials
Table
Filling
material
)
ZOE IRM EBA CAZI
with
Fig. 4. Photomierograph EBA.
= = = .= =
Inflammation No response Mild Moderate Severe Pulp necrosis
(reparative)
dentine
(in microns)
1 week
2 weeks
3 weeks
10 0 1::
36 22 29 108
24 10 83 104
showing
formation
of irregular
drntine
in Z-week specimen filled
130
Bhaskar
Fig.
Fig.
et al.
03..
O.M. & O.P. .July, 1969
5
6
Pig. 5. Irregular Pig. 6. Irregular
dentine in tooth filled with CAZl, Z-week speeimcm dentine in response to ERA, Y-week specimen.
seen in only two cases. Measurements showed that the maximum thickness of reparative dentine in these two teeth was 40 microns. IRM. Mild lymphocytic infiltrate was seen in one pulp disruption of odontoblastic layer also occurred in one case, but irregular de.ntine was not seen in any of the examined teeth. EBA. In one of the seven teeth examined the pulp showed a mild lymphocytic infiltrate, and in another the cellular infiltrate was moderate. Odontoblastic disruption was seen in two pulps, and in one an irregular dentine layer 52 microns in maximal thickness was observed. CAZI. The pulps of three teeth filled with CAZI showed a mild lymphocytic infiltrate and disruption of odontoblasts. Irregular dentine 54 microns in maximal thickness was seen in one tooth.
Volume Number
Two
28 1
Pulpal
response to four
restorative
materials
131
weeks
ZOE. Two of the seven teeth in which the restoration had been in place for 2 weeks showed a moderate lymphocytic infiltrate in the pulp, and one showed mild lymphocytic infiltration. Two teeth showed moderate disruption of odontoblasts. Irregular dentine was seen in two teeth, and its maximal thickness was 182 microns. IRJl. One of the six teeth examined showed a micro-abscess, and in two teeth mild lymphocytic infiltrate could be seen. Mild to moderate disruption of the odontoblastic layer was seen in two cases. Irregular dent.ine was seen in three of the six cases, and its maximal thickness was 69 microns. EBA. Of the seven teeth examined, two showed a mild inflammatory cell response and one showed a moderate response. Evidence of mild to moderate odontoblastic disruption W:SSseen in two cases. Five of the seven teeth showed irregular dentine, which at its maximal thickness measured 51 microns. C&1. In all cases the pulp showed a mild to moderate infiltration with lymphocytes. Four teeth revealed a moderate disruption of odontoblasts, and irregular dentine was seen in six teeth. The maximal thickness of the new dentine was 290 microns. Three
weeks
ZOE. Four teeth showed mild lymphocytic infiltrate, and a minimal disruption of odontoblastic layer was seen only in two cases. In three pulps irregular dentine, which measured 89 microns at its maximal thickness, was seen. TRM. Five teeth showed minimal lymphoeytic infiltrate, and in one the infiltrate was classified as moderate. Minimal disruption of odontoblastic layer was seen in three pulps, and a moderate disruption was evident in one pulp. Irregular dentine was seen in one tooth, and its maximal thickness was 58 microns. ERA. In the seven teeth, lymphocytic infiltrate was mild in five cases and moderate in one. All cases revealed disruption of the odontoblastic layer (five of mild and two of moderate severity). Irregular dentine was found in six of the seven teeth, and its maximal thickness was 22 microns. CAZI. Of the six teeth, the pulp in one was lost during preparation and this tooth is therefore excluded from the study. In three cases the pulps showed mild lymphocytic infiltrate, and in two the infiltrate was classified as moderate. Moderate odontoblastic disruption was seen in four cases, and in one instance the odontoblastic disruption was minimal. The irregular dentine was observed in all cases and, at its maximal thickness, measured 152 microns. DISCUSSION
In a previous study the tissue response to a cyanoacrylate-containing dental cement was compared with the response to zinc oxide and eugenol. It was observed in that study thal; the tissue response to these materials is comparable.” On the basis of the present investigation, it would appear that all of the experimental filling materials (IRM, EBA, and CAZI) are biologically acceptable to the dental pulp. A micro-abscess was seen in only one tooth which had
132
Bha,skar et al.
received an IRM restoration. A comparison of the odontoblastie clisrul)tion in the pulp showed that the odontoblastic tlisrupt.ion was least under zinc oxide and eugenol and that it was maximal unclcr the CAZI (Table II). Ilowvcver, it was less than what could be elassifietl as moderate (Table II). Since the irregular dentine is formed as a result of “trauma” to the odontoblasts, it is not surprising that the thickness of the secontlary dcntinc was greatest under the evanoarrylate restoration (Table III). The degree of cellular infilt.rate in the pulps of teeth restored with the four materials revealed that, with the exception of one tooth (IRM), the pulpal inflammation in a,11cases was minimal and reversible. However, a comparison between the four materials again showed that the zinc oxide a,nd eugcnol fillings elicited a somewhat milder response than the other three materials (Table II). This finding is consistent with the amount of dentine produced under t.hese restorative materials. From the observations made in this study, one might draw the following conclusions : 1. All three of the experimental restorative materials are biologically acceptable to the dental pulp. In no case would the pulpal response be classified as severe, and pulps were found vital in all teeth. 2. The degree of odontoblsstic disruption and inflammatory infiltrate, though minimal in all cases, was more pronounced in the experimental materials than in the ZOE. The response to CAZI was more marked than the response to the other two experimental materials, but t,he difference was not remarkable (Table 11). 3. The reparative dentine formed in the pulp was proportional to the severity of odontoblastic disruption and the inflammatory infiltrate. 4. At 3 weeks the reparative dentine layer was much thicker in teeth restored with CAZI and EBA than in teeth filled with IRM and ZOE. 5. Whereas all three of the restorative materials tested appear biologically suitable, it would seem that, on the basis of their dentine-producing qualities, t.he EBA and CAZI should be particularly valuable as a cavity base in indirect pulp capping. 6. Since all of the experimental materials tested appear biologically acceptable as semipermanent restorative materials, their physical properties and their reaction to the oral environment should be the decisive factors. SUMMARY
This study deals with pulpal response to four types of restorative material. Class V cavities were prepared in seventy-eight teeth of three miniature swine and were restored with zinc oxide and eugenol, a commercially available product called IRM, a mixture of ethoxybenzoic acid with fillers called EBA, and a mixture of isobutyl cyanoacrylate and zinc phosphate called CAZI. The animals were killed after 1, 2, and 3 weeks, and the teeth were examined microscopically. This study revealed the following : 1. With the exception of one tooth, which showed a micro-abscess, irreversible pulp damage was not. observed.
Volume Number
28 1
Pulpal
response to four restorative
materials
133
2. All three of the restorative materials appear biologically acceptable to the dental pulp. 3. Odontoblastic disruption and inflammatory infiltrate were not severe in any case. They were, however, least marked in the zinc oxide and eugenol restorations and most prominent in teeth restored with cyanoacrylate-containing restorative material. 4. The layer of reparative dentine formed in response to the filling materials was proportional to the degree of odontoblastic disruption and the inflammatory infiltrate. It was more prominent in those teeth which were restored with CAZI and EBA than in teeth filled with the other materials. 5. It appears from this study that any of the three experimental materials tested could be used as filling materials. However, in cases in which the therapeutic aim is to acquire a thick layer of reparative dentine, a cavity base with either the EBA or CAZI would be preferable. On the other hand, where these materials are to be used as semipermanent restorations rather than as cavity bases, their physical properties and their resistance to the oral environment should be the decisive factors. REFERENCES
D. : Polymerically R,einforced EBA Cement. 1. Brauer, G. M., Huget, E. F., and Termini, (Unpublished Data.) 2. Civjan, H., Margetis, P. M., and Reddick, R. L.: Properties of 12 Butyl Alpha Cyanoacrylate R.estorative Materials, I.A.D.R. Absts., p. 94, 1968. 3. Stanley, Harold, R.: Design for a Human Pulp Study. Part I, ORAL SURG., ORAL MED. 8; ORAL PATH.~~: 633.647,1968. P.: Tissue Response to a Butyl Cyanoacrylate 4. Bhaskar, H. N., Friscb, J’., and Margetis, Containing Dental Cement, J. D. Res. 48: 57-69, 1969.
Federal dental services Pulpal response to four restorative materials Xurindar N. Bhaskar, Colonel, DC, USA,” Duane E. Cutright, Lieute?bant Colollel, DC, USA,** Joe D. Beasley, Major, DC, UXA,*** and Robert C. Boyers, Lieutenant Colonel, DC, UXA”“KX UNITED
STATES
WALTER
REED
INSTITIJTE
ARMY ARMY
MEDICAL
OF DENTAL
CENTER,
RESEARCH,
WASHINGTON,
D.C.
I
n order to provide maximal dental care for patients with multiple lesions, the ideal restorative material would be one that could be inserted without elaborate cavity preparation and that could serve the patient on a semipermanent basis. The advantage of such a mat.erial lies in the fact that multiple carious lesions could be excavated a.nd restored at a single visit, with permanent restorations provided at a future date. For this purpose, two restorative materials were developed at the dental research sections of the National Bureau of Standards and the United States Army Institute of Dental Research, and a, t,hird was selected from a commercial source.‘, 2 Since, in addition to having appropriate physical properties, a restorative material must also be biologically acceptable to the dental pulp, the present study was undertaken to test the pulpal response of three experimental filling materials and one control material. METHODS .AND MATERIALS The four filling materials tested in this study were the following: No. 1 (control)-Zinc oxide and eugenol (ZOE) . No. Z-Intermediate restorative material referred to in the ensuing description as IRM. This is a commercial polymethylmethacrylate-reinforced zinc oxide-eugenol product of 1~. I). Caulk Company, Milford, Delaware. No. J-Referred to in the ensuing description as ERA, it consists of the following : *Chief, Division of Oral Pathology. **Oral Pathologist, Division of Oral Pathology. ***Resident, Division of Oral Pathology. ****Assistant Chief, Division of Oral Pathology.
126
Volume Number
28 1
Pulpal
respome to four restorative
materials
127
Powder Liquid Zinc oxide 57.0% o-Ethoxybenzoic acid 662/3% Aluminum oxide 28.0% Eugenol 33Y3% A copolymer of 9.5% methylmethac~~late Rosin 5.5% h70. 4-Referred to in the ensuing description as CA.21, it consists of the following : Powder Liquid Zinc phosphate 85.0% Isobutyl-a-cyanoacrylate Zinc oxide 15.0% monomer (sterile) The components of the experimental formulations No. 3 and No. 4 were USP and reagent grade. Three miniature pigs were anesthetized with pentosol, and Class V cavities were made with a No. 35 inverted cone bur at 150,000 r.p.m. in a total of seventyeight teeth, as shown in Table I. All cavities were prepared by the same operator, and an attempt was made to keep the cavity depths at the same level. Twentysix teeth were filled in each pig (Table I). A total of twenty-one teeth were filled with zinc oxide and eugenol, eighteen with IRM, twenty-one with EBA, and eighteen with CAZI:. In order to assure uniformity, cavity preparations, mixing of the filling materials, and insertion of t,he fillings were done by three separate operators, respectively. Animals were killed 1, 2, and 3 weeks postoperatively. Teeth were recovered with blocks of surrounding bone, the apical third was cut with rongeurs, and the specimens were fixed in 10 per cent formalin. After decalcification and paraffin embedding, sections were cut at 6 microns and stained with hematox ylin and eosin. FINDINGS
Pulps in all teeth were vital. The pulpal response to the restorative materials was measured by the degree of disruption of the oclontoblastic layer under the cavity preparation (Fig. 1) and by the number and type of inflammatory cells seen in the area (Figs. 2 and 3).3 In order to quantify the pulpal response, the degree of odontoblastic d!isruption and inflammation was graded from 0 to 4, as indicated in Table II. In addition to the odontoblastic disruption and the inflammatory cells, the pulpal response was char.scterized by the formation of new dentine (Figs. 4 to Table I. Filling materials included in the study
tested, postoperative Nuder
_Filling
material
Zinc oxide and eugenol IRM EBA Cyanoacrylate mixture Totals
1 week i 6’ 26
1
periods, and number
of teeth
teeth used
of
8 weeks
)
3 weeks
Total
7 6 7 6
21 18 21 18
7 6 i 26
s
18
128
Bhusknr
OS., O.M. & O.P. July, 1969
et ccl.
Pig. 2. Pulp from tooth ruption of odontoblasts.
which
was filld
with
ERtl
one week postoperatively.
S&e
;Lis-
Fig.
F
Pigs. d and 3. Lowone week postoperatively.
and high-power photomicrographs Noto arca of inflammation.
of pulp of tooth filled
with
CA21
6). This dentine was producetl on the pulpal wall opposite the area of the restorations and could be easily distinguished from the pre-experimental dentine by a line of demarcation, the so-called calciotraumatic line (Figs. 4 t,o 6). In addition, the newly formed dent,ine (irregular or rcpa.ratixc dentine) could be identified by the reduction in the number of its dentinal tubules and by its lighter staining qualities (Fig. 4). The pulpal response to various filling materials is given below and is summarized in Tables II and III. One
week
ZOE. In three teeth pulp showed neutrophil case was there a disruption of the odontoblastic
infiltration, and in only one layer. Irregular dentine was
Volume 28 Number 1
Pulpal
II. Average disruption four restorative materials* Table
Postoperative‘ period (weelcs)
to four
response
of odontoblasts
restorative
and inflammatory
Disruption odontoblastic
NateGal
of layer
materials
response to the InfEammatory response (l-4) 0.4 0.3 0.5 1.0
I
Zinc: oxide and eugenol IRM EBA Cyanoacrylate
0.2 0.3 it;
2
Zinc: oxide and eugenol IRJC EBA Cyanoacrylate
0.7 1.2 0.8 1.2
0.6 1.0 0.6 1.4
3
Zinc: oxide and eugenol IRSC EBA Cpanoacrylate
1.0 1.2 1.3 1.8
0.8 1.2 1.0 1.4
: Odontoblastic airruption 0 1 Layer intact 1 = Evidence of disruption 2 = Partial disruption 3 = Complete disruption 4 = Pulp ncrosis
129
*Grading
0 1 2 3 4
Ill. Average thickkness of irregular under the four filling materials
Table
Filling
material
)
ZOE IRM EBA CAZI
with
Fig. 4. Photomierograph EBA.
= = = .= =
Inflammation No response Mild Moderate Severe Pulp necrosis
(reparative)
dentine
(in microns)
1 week
2 weeks
3 weeks
10 0 1::
36 22 29 108
24 10 83 104
showing
formation
of irregular
drntine
in Z-week specimen filled
130
Bhaskar
Fig.
Fig.
et al.
03..
O.M. & O.P. .July, 1969
5
6
Pig. 5. Irregular Pig. 6. Irregular
dentine in tooth filled with CAZl, Z-week speeimcm dentine in response to ERA, Y-week specimen.
seen in only two cases. Measurements showed that the maximum thickness of reparative dentine in these two teeth was 40 microns. IRM. Mild lymphocytic infiltrate was seen in one pulp disruption of odontoblastic layer also occurred in one case, but irregular de.ntine was not seen in any of the examined teeth. EBA. In one of the seven teeth examined the pulp showed a mild lymphocytic infiltrate, and in another the cellular infiltrate was moderate. Odontoblastic disruption was seen in two pulps, and in one an irregular dentine layer 52 microns in maximal thickness was observed. CAZI. The pulps of three teeth filled with CAZI showed a mild lymphocytic infiltrate and disruption of odontoblasts. Irregular dentine 54 microns in maximal thickness was seen in one tooth.
Volume Number
Two
28 1
Pulpal
response to four
restorative
materials
131
weeks
ZOE. Two of the seven teeth in which the restoration had been in place for 2 weeks showed a moderate lymphocytic infiltrate in the pulp, and one showed mild lymphocytic infiltration. Two teeth showed moderate disruption of odontoblasts. Irregular dentine was seen in two teeth, and its maximal thickness was 182 microns. IRJl. One of the six teeth examined showed a micro-abscess, and in two teeth mild lymphocytic infiltrate could be seen. Mild to moderate disruption of the odontoblastic layer was seen in two cases. Irregular dent.ine was seen in three of the six cases, and its maximal thickness was 69 microns. EBA. Of the seven teeth examined, two showed a mild inflammatory cell response and one showed a moderate response. Evidence of mild to moderate odontoblastic disruption W:SSseen in two cases. Five of the seven teeth showed irregular dentine, which at its maximal thickness measured 51 microns. C&1. In all cases the pulp showed a mild to moderate infiltration with lymphocytes. Four teeth revealed a moderate disruption of odontoblasts, and irregular dentine was seen in six teeth. The maximal thickness of the new dentine was 290 microns. Three
weeks
ZOE. Four teeth showed mild lymphocytic infiltrate, and a minimal disruption of odontoblastic layer was seen only in two cases. In three pulps irregular dentine, which measured 89 microns at its maximal thickness, was seen. TRM. Five teeth showed minimal lymphoeytic infiltrate, and in one the infiltrate was classified as moderate. Minimal disruption of odontoblastic layer was seen in three pulps, and a moderate disruption was evident in one pulp. Irregular dentine was seen in one tooth, and its maximal thickness was 58 microns. ERA. In the seven teeth, lymphocytic infiltrate was mild in five cases and moderate in one. All cases revealed disruption of the odontoblastic layer (five of mild and two of moderate severity). Irregular dentine was found in six of the seven teeth, and its maximal thickness was 22 microns. CAZI. Of the six teeth, the pulp in one was lost during preparation and this tooth is therefore excluded from the study. In three cases the pulps showed mild lymphocytic infiltrate, and in two the infiltrate was classified as moderate. Moderate odontoblastic disruption was seen in four cases, and in one instance the odontoblastic disruption was minimal. The irregular dentine was observed in all cases and, at its maximal thickness, measured 152 microns. DISCUSSION
In a previous study the tissue response to a cyanoacrylate-containing dental cement was compared with the response to zinc oxide and eugenol. It was observed in that study thal; the tissue response to these materials is comparable.” On the basis of the present investigation, it would appear that all of the experimental filling materials (IRM, EBA, and CAZI) are biologically acceptable to the dental pulp. A micro-abscess was seen in only one tooth which had
132
Bha,skar et al.
received an IRM restoration. A comparison of the odontoblastie clisrul)tion in the pulp showed that the odontoblastic tlisrupt.ion was least under zinc oxide and eugenol and that it was maximal unclcr the CAZI (Table II). Ilowvcver, it was less than what could be elassifietl as moderate (Table II). Since the irregular dentine is formed as a result of “trauma” to the odontoblasts, it is not surprising that the thickness of the secontlary dcntinc was greatest under the evanoarrylate restoration (Table III). The degree of cellular infilt.rate in the pulps of teeth restored with the four materials revealed that, with the exception of one tooth (IRM), the pulpal inflammation in a,11cases was minimal and reversible. However, a comparison between the four materials again showed that the zinc oxide a,nd eugcnol fillings elicited a somewhat milder response than the other three materials (Table II). This finding is consistent with the amount of dentine produced under t.hese restorative materials. From the observations made in this study, one might draw the following conclusions : 1. All three of the experimental restorative materials are biologically acceptable to the dental pulp. In no case would the pulpal response be classified as severe, and pulps were found vital in all teeth. 2. The degree of odontoblsstic disruption and inflammatory infiltrate, though minimal in all cases, was more pronounced in the experimental materials than in the ZOE. The response to CAZI was more marked than the response to the other two experimental materials, but t,he difference was not remarkable (Table 11). 3. The reparative dentine formed in the pulp was proportional to the severity of odontoblastic disruption and the inflammatory infiltrate. 4. At 3 weeks the reparative dentine layer was much thicker in teeth restored with CAZI and EBA than in teeth filled with IRM and ZOE. 5. Whereas all three of the restorative materials tested appear biologically suitable, it would seem that, on the basis of their dentine-producing qualities, t.he EBA and CAZI should be particularly valuable as a cavity base in indirect pulp capping. 6. Since all of the experimental materials tested appear biologically acceptable as semipermanent restorative materials, their physical properties and their reaction to the oral environment should be the decisive factors. SUMMARY
This study deals with pulpal response to four types of restorative material. Class V cavities were prepared in seventy-eight teeth of three miniature swine and were restored with zinc oxide and eugenol, a commercially available product called IRM, a mixture of ethoxybenzoic acid with fillers called EBA, and a mixture of isobutyl cyanoacrylate and zinc phosphate called CAZI. The animals were killed after 1, 2, and 3 weeks, and the teeth were examined microscopically. This study revealed the following : 1. With the exception of one tooth, which showed a micro-abscess, irreversible pulp damage was not. observed.
Volume Number
28 1
Pulpal
response to four restorative
materials
133
2. All three of the restorative materials appear biologically acceptable to the dental pulp. 3. Odontoblastic disruption and inflammatory infiltrate were not severe in any case. They were, however, least marked in the zinc oxide and eugenol restorations and most prominent in teeth restored with cyanoacrylate-containing restorative material. 4. The layer of reparative dentine formed in response to the filling materials was proportional to the degree of odontoblastic disruption and the inflammatory infiltrate. It was more prominent in those teeth which were restored with CAZI and EBA than in teeth filled with the other materials. 5. It appears from this study that any of the three experimental materials tested could be used as filling materials. However, in cases in which the therapeutic aim is to acquire a thick layer of reparative dentine, a cavity base with either the EBA or CAZI would be preferable. On the other hand, where these materials are to be used as semipermanent restorations rather than as cavity bases, their physical properties and their resistance to the oral environment should be the decisive factors. REFERENCES
D. : Polymerically R,einforced EBA Cement. 1. Brauer, G. M., Huget, E. F., and Termini, (Unpublished Data.) 2. Civjan, H., Margetis, P. M., and Reddick, R. L.: Properties of 12 Butyl Alpha Cyanoacrylate R.estorative Materials, I.A.D.R. Absts., p. 94, 1968. 3. Stanley, Harold, R.: Design for a Human Pulp Study. Part I, ORAL SURG., ORAL MED. 8; ORAL PATH.~~: 633.647,1968. P.: Tissue Response to a Butyl Cyanoacrylate 4. Bhaskar, H. N., Friscb, J’., and Margetis, Containing Dental Cement, J. D. Res. 48: 57-69, 1969.