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Pulp healing subjacent to corticosteroid-covered and amalgam-covered dentin
endodontics Editor: MILTON
SISKIN,
D.D.S.
College of Dentistry The University of Tennessee 847 Monroe Avenue Memphis, Tennessee 3 8 163
Pulp healing subjacent to corticosteroidcovered and amalgam-covered dentin I. A. Mjiir, B.D.S., M.S.D., MA’., dr.odont., Oslo, Norway NIOM,
SCANDINAVIAN
OF ANATOMY,
DENTAL
INSTITUTE FACULTY,
OF
DENTAL
UNIVERSITY
and T. Lervik, MATERIALS,
AND
candodont., DEPARTMENT
OF OSLO
Pulp inflammation was induced by placing soft carious human dentin and amalgam in Class V cavities prepared in sixty-five monkey teeth. These fillings were removed after 7 days, and the cavities were restored with either a corticosteroidcontaining cement and amalgam or amalgam only. The teeth were then removed after 7, 44, and 104 days. Healing occurred subjacent to both corticosteroid-covered and amalgam-covered dentin, but the healing subjacent to amalgam-covered dentin was gemrally less complete during the observation periods available.
R
estorative materials are usually placed in cavities prepared in carious teeth. Such teeth exhibit structural alterations in the dentin and pulp to a variable and clinically unpredictable degree. The lack of correlation between clinical diagnosis and the histopathology of the pulp7 makes it impossible to use carious teeth in testing the effect of restorative materials on the pulp and dentin. Investigations have therefore been focused on the reactions which restorative materials produce in intact teeth, with normal pulp structure as a base line.2, 3 It is uncertain whether these results obtained from intact teeth are valid or comparable to those that may occur in carious teeth which often have inflamed pulps. Experimental techniques which allow the testing of the effect of restorative materials on teeth with inflamed pulps have been developed,4 and pulp inflammation may be induced experimentally with a fair degree of reproducibility. One such technique has been employed in the present study, and pulp healing has been evaluated following the use of a corticosteroid-containing cement as a 789
790
.Ifjijr
trjttl
Table
I. I )istrilmtion
Oral Surg. IkccnllKT, 1975
I,ertik
of material after illtluction 1
Observation period (days)
of pulpitis
Amalgam only
Corticosteroid cement/amalgam
fA 10
11: 12
4:
104
base iintl(~* amalgam 01’ ly- using amalgam alone to restore cavities iii teeth with inflanic‘tl pulps. MATERIALS
AND
METHODS
Severe pulp inflammation was inducyyl by restoring Class V buc+cal caavities prepared in monkey (Jlaccrccr irks) teeth with soft carious human tlentin on tht> pulpal surface as a “base” and then scaling the cavity with amalgam for 7 days. This proc*cdurc will usually result in a scverp hut localized cellular infiltration and destruc+tion of the odontohlast la~er.~ Following the induction of severe pulp inflammation, the initial fillings were carefully removed after 7 (lays. The cavities were then restored with either a corticosteroid-containing cement (Iiedcrmis) and amalgam or amalgam only. The ttbc>th JVVI’Ccstractecl after subsequent observation periods of 7, 44, and 10-I (lays. A total of sixty-five teeth from six monkeys were usctl, and the tlistrihution of the lrlaterial is shown in Table 1. All teeth wcrc trtatctl according to the same histologic procdcdurc ill\olving formalin fixation, demineralixation, paraffin cmbccltliiig, srctioning, ant1 staining iii hematosylin and cosin. The pulp reactions \vcre classifictl as none , slight, moderate, or scvcrc, accordpresc>lcctcd System.’ In addition, thtl amount of irregular sccondar) ing to dentin fO1’1lliltiO11sul~jacwit to tlic cavities was iiotetl. il
OBSERVATIONS Seven-day
observation
period
(Figs.
1 to 4)
Slight, moderate, ant1 severe pulp reactions were observed, but severe reactions were seen only occasionally. Signs of increased secondary dentin formation were noted, cvcn after ‘7 days, subjacent to both corticosteroid-covered and amalgam-covered dentin (Figs. 1 to 4). The irregular secondary dentin often had cellular inclusions (Figs. 2 to 4)) but in some areas where the cellular accumulations were particularly intense no irregular secondary dentin had formecl (Figs. 3 and 1). ?;o difference between the two groups was noted. Forty-four-day
observation
period
(Figs.
5 and
6)
Often no pulp inflammation was found subjacent to corticostcroid-covered dentin (Fig. 5). ldargc masses of irregular secondary dentin, which occasionall;v had cellular inclusions at the intcrfacc bctwcen primary antI secondary tientin, were noted. About llalf the teeth with corticostcroid-covered dentin showed this type of response, while the other half exhibited a slight pulp reaction in addition to irregular secondary tleritin formation. One tooth had an unusual histopathologie appearance which must be assumed to have been due to technical problems.
Volume 40 Number 6
Pulp
healing and restorative
materials
791
Pig. 1. Cavity (C) had been filled with soft carious human dentin and amalgam for 7 days and then with a corticosteroid-containing cement and amalgam for 7 days after the first filling had been removed. Irregular secondary dentin (SD) has started to form and a slight cellular infiltration is present. (Magnification, x50.) Pig. b. Higher magnification of an area at the pulp/dentin interface from Fig. 1. Note cellular inclusions in the irregular secondary dentin (SD). (Magnification, x150.) Fig. 3. Cavity (C) had heen filled with soft carious human dentin for 7 days and then with amalgam for 7 days after the first filling had been removed. Irregular secondary dentin (SD) had formed subjacent to the cavity except in one area (arrozu) where severe cellular infiltration persisted. (Magnification, x50.) Fig. 4. Pulp/dentin region in the location corresponding to the severe cellular infiltration shown in Fig. 3. No predentin or irregular secondary dentin is found corresponding to the severe cellular infiltration. (Magnification, x280.)
Oral Surg. December, 1975
Fig. 5. Pulp/dentin region subjacent to cavity which had been filled with soft carious human dentin and amalgam for 7 days and then with a corticosteroid-containing cement and amalgam for 44 days after the first filling had been removed. Note extensive secondary dentin (Li’D) formation with cellular inclusions (arrow). (Magnification, x100.) Fig. 6. Cavity (C) had been filled with soft carious human dentin for 7 days and then with amalgam for 44 days after the first filling had been removed. Secondary dentin (SD) has formed subjacent to the cavity, but severe inflammaticn persists in the pulp. (Magnification, x100.)
The pulp reactions subjacent to amalgam-covered dentin after 14 days’ observation time varied considerably. They were usually classified as slight, but teeth with severe reactions (Fig. 6) as well as those with no signs of pulp inflammation were noted. One-hundred-four-day
observation
period
(Figs. 7 to 10)
After a SO4day observation period the reactions noted in all teeth were characterized by large masses of irregular secondary dentin subjacent to the cavities. No pulp reactions were found subjacent to corticosteroid-covered dentin or in about half of the teeth with amalgam-covered dentin (Figs. 7 to 9). In the remaining teeth with amalgam-covered dentin, the pulp reactions were classified as slight (Fig. 10) and included hyperemia and a slight cellular infiltration. Large masses of irregular secondary dentin had formed subjacent to all cavities. Cellular inclusions were often present in the first-formed irregular secondary dentin, but the rest of it had a fairly uniform, tubular structure (Figs. 7 and 9). No cell-free zone was observed subjacent to the odontoblast layer bordering the masses of irregular secondary dentin, but this is often found in situations with an increased rate of irregular secondary dentin formation. The healing is considered completed at this stage (Figs. 7 to 9).
Volume 40 Number 6
Pulp
healing and restorative
materials
793
Fig. 7. Irregular secondary dentin (SD) subjacent to a cavity which had been filled with soft carious human dentin and amalgam for 7 days and then with a corticosteroid-containing cement and amalgam for 104 days after the first filling had been removed. A few cellular is found in the pulp. inclusions are seen close to the primary dentin. No inflammation (Magnification, x100.) Fig. 8. Cavity (C) had been filled with soft carious human dentin and amalgam for 7 days and then with amalgam for 104 days after the first filling had been removed. Irregular secondary dentin (SD) has formed subjacent to the cavity, and no or only very slight evidence of inflammation is found in the pulp. (Magnification, x40.)
DISCUSSION The regularity and uniformity of the response initiated by the first fillings with soft carious human dentin and amalgam are important for an assessment of the healing capacity of the materials used. Previous studies have shown that severe pulp inflammation occurs regularly with this technique, and it is considered to give reproducible responses within acceptable biologic limits.4 These observations have been confirmed by us (unpublished observations). The results from the series with 7 days’ healing also indicate that severe pulp reactions had been induced by the initial experimental procedure. In some teeth severe inflammation persisted in certain areas (Figs. 3 and 4)) while in other areas, where fairly marked healing had taken place (Figs. 1 and 2)) more irregular secondary dentin had formed than if similar restorations had been inserted in intact monkey teeth. 5, G It must be assumed, therefore, that the intended pulp inflammation had been induced by the initial experimental procedure. On this basis, it may be concluded that healing of localized pulp inflammation may occur subjacent to both corticosteroid-covered and amalgamcovered dentin, but that it occurs more slowly and with less regularity under amalgam-covered dentin. The corticosteroid-containing cement used in the present study contains
Oral Surg. l)oeeml~er, 1975
Fig. 9. liigher magnification of an area from Fig. 8. The thick layer of irregular secondary dentin (SD) has cellular inclusions fn~ozc,) close to the primary dentin. No inflammation is found in the pulp. (Magnification, x100.) Fig. 10. Irregular secondary dentin (SD) subjacent to a cavity xvhich had been filled with soft, carious human dentin and amalgam for 7 days and then mith amalgam for 104 days after the first filling had been removed. Hyperemia and a slight cellular infiltration in the pulp tissutl are seen. (Magnification, x100.)
an antibiotic and other ingredients in addition to a corticosteroid. However, this cement did not exhibit an additional healing effect when used in the present experimental s-ystem, as compared to that seen subjacent to calcium-hytlroxidecovered and zinc-oside-eugcnol-covered dentin .? In fact, the results were quite similar when these three types of cement base were used. The healing subjacent to amalgam-covered dentin was somewhat delayed in time and generally less complete as compared to the cement-covered dentin used in this and previous7 studies. The cavities used were relatively deep, that is, in the pulpal half of the dentin. Clinical experience indicates that if such cavities arc restored without a lining or base, discomfort may persist for some time. The somewhat delayed healing under amalgam-covered dentin therefore supports clinical observations. Histologic studies of the effect on the pulp following the insertion of deep, unlined restorations in intact teeth also suggest that irritation may be caused by such fillings.8* 9 CONCLUSIONS
Healing of induced pulpitis may take place subjacent to corticosteroidcovered and amalga,m-covered dentin under the present experimental conditions. Marked healing occurs within the first 7 days. The reactions subjacent to corticosteroid-covered dentin were similar to those found in response to calciumhydroxide-covered and zinc-oxide-and-eugenol-covered dentin reported previously. The healing subjacent to amalgam-covered dentin was less complete during the
Pulp
healing
and restorative
materials
795
observation periods available as compared to that subjacent to calciumhydroxide-covered, zinc-oxide-and-eugenol-covered, and corticosteroid-covered dentin used in this experimental system. These findings are considered to be in accordance with clinical experience in that more discomfort is generally experienced by patients if deep, unlined amalgam restorations are placed than if restorations with a base material are inserted. REFERENCES 1. Massler, M.: Pulp Reactions
to Dental Caries, Int. Dent. J. 17: 441-460, 1967. 2. Langeland, K. : Tissue Changes in the Dental Pulp ; an Experimental Histologic Study, Odontol. Tidskr. 65: 239-386. 1957. 3. Langeland, I?., D&den, %. ‘E.j Tronstad, L., and Langeland, L. K. : Human Pulp Changes of Iatroeenic Oriein. ORAL SURQ. 32: 943-980. 1971. 4. Mjb;r, I.-A., and-Trbnstad, L.: Experimentally Induced Pulpitis, ORAL SURG. 34: 102-108,
1972.
Materials, 5. Tronstad, L., and MjSr, I. A.: Pulp Reactions to Calcium Hydroxide-Containing ORAL SURG. 33: 961-965. 1972. 6. Erikseh, H. M.: Protective Effect of Dift’erent Lining Materials Placed Under Composite Resin Restorations in Monkeys. Stand. J. Dent. Res. 82: 373-380, 1974. 7. MjBr, I. A., and Tronstad; L.: The Healing of Experimentally Induced Pulpitis, ORAL SURG. 38: 115-121, 1974. Zinc Oxide/Eugenol and Amalgam on the 8. Mjiir, I. A.: The Effect of Calcium Hydroxide, Pulp, Odontol. Tidskr. 71: 94-105, 1963. 9. MGllcr, B., and Granath, L.-E.: Reaction of the Human Dental Pulp to Silver Amalgam Restorations, Acta Odontol. &and. 31: X37-192, 1973.
Reprint
requests
to:
Dr. Ivar A. MjBr NIOM Scandinavian Institute Forskningsveien 1 Oslo 3, Norway
of Dental
Materials
SISKIN,
D.D.S.
College of Dentistry The University of Tennessee 847 Monroe Avenue Memphis, Tennessee 3 8 163
Pulp healing subjacent to corticosteroidcovered and amalgam-covered dentin I. A. Mjiir, B.D.S., M.S.D., MA’., dr.odont., Oslo, Norway NIOM,
SCANDINAVIAN
OF ANATOMY,
DENTAL
INSTITUTE FACULTY,
OF
DENTAL
UNIVERSITY
and T. Lervik, MATERIALS,
AND
candodont., DEPARTMENT
OF OSLO
Pulp inflammation was induced by placing soft carious human dentin and amalgam in Class V cavities prepared in sixty-five monkey teeth. These fillings were removed after 7 days, and the cavities were restored with either a corticosteroidcontaining cement and amalgam or amalgam only. The teeth were then removed after 7, 44, and 104 days. Healing occurred subjacent to both corticosteroid-covered and amalgam-covered dentin, but the healing subjacent to amalgam-covered dentin was gemrally less complete during the observation periods available.
R
estorative materials are usually placed in cavities prepared in carious teeth. Such teeth exhibit structural alterations in the dentin and pulp to a variable and clinically unpredictable degree. The lack of correlation between clinical diagnosis and the histopathology of the pulp7 makes it impossible to use carious teeth in testing the effect of restorative materials on the pulp and dentin. Investigations have therefore been focused on the reactions which restorative materials produce in intact teeth, with normal pulp structure as a base line.2, 3 It is uncertain whether these results obtained from intact teeth are valid or comparable to those that may occur in carious teeth which often have inflamed pulps. Experimental techniques which allow the testing of the effect of restorative materials on teeth with inflamed pulps have been developed,4 and pulp inflammation may be induced experimentally with a fair degree of reproducibility. One such technique has been employed in the present study, and pulp healing has been evaluated following the use of a corticosteroid-containing cement as a 789
790
.Ifjijr
trjttl
Table
I. I )istrilmtion
Oral Surg. IkccnllKT, 1975
I,ertik
of material after illtluction 1
Observation period (days)
of pulpitis
Amalgam only
Corticosteroid cement/amalgam
fA 10
11: 12
4:
104
base iintl(~* amalgam 01’ ly- using amalgam alone to restore cavities iii teeth with inflanic‘tl pulps. MATERIALS
AND
METHODS
Severe pulp inflammation was inducyyl by restoring Class V buc+cal caavities prepared in monkey (Jlaccrccr irks) teeth with soft carious human tlentin on tht> pulpal surface as a “base” and then scaling the cavity with amalgam for 7 days. This proc*cdurc will usually result in a scverp hut localized cellular infiltration and destruc+tion of the odontohlast la~er.~ Following the induction of severe pulp inflammation, the initial fillings were carefully removed after 7 (lays. The cavities were then restored with either a corticosteroid-containing cement (Iiedcrmis) and amalgam or amalgam only. The ttbc>th JVVI’Ccstractecl after subsequent observation periods of 7, 44, and 10-I (lays. A total of sixty-five teeth from six monkeys were usctl, and the tlistrihution of the lrlaterial is shown in Table 1. All teeth wcrc trtatctl according to the same histologic procdcdurc ill\olving formalin fixation, demineralixation, paraffin cmbccltliiig, srctioning, ant1 staining iii hematosylin and cosin. The pulp reactions \vcre classifictl as none , slight, moderate, or scvcrc, accordpresc>lcctcd System.’ In addition, thtl amount of irregular sccondar) ing to dentin fO1’1lliltiO11sul~jacwit to tlic cavities was iiotetl. il
OBSERVATIONS Seven-day
observation
period
(Figs.
1 to 4)
Slight, moderate, ant1 severe pulp reactions were observed, but severe reactions were seen only occasionally. Signs of increased secondary dentin formation were noted, cvcn after ‘7 days, subjacent to both corticosteroid-covered and amalgam-covered dentin (Figs. 1 to 4). The irregular secondary dentin often had cellular inclusions (Figs. 2 to 4)) but in some areas where the cellular accumulations were particularly intense no irregular secondary dentin had formecl (Figs. 3 and 1). ?;o difference between the two groups was noted. Forty-four-day
observation
period
(Figs.
5 and
6)
Often no pulp inflammation was found subjacent to corticostcroid-covered dentin (Fig. 5). ldargc masses of irregular secondary dentin, which occasionall;v had cellular inclusions at the intcrfacc bctwcen primary antI secondary tientin, were noted. About llalf the teeth with corticostcroid-covered dentin showed this type of response, while the other half exhibited a slight pulp reaction in addition to irregular secondary tleritin formation. One tooth had an unusual histopathologie appearance which must be assumed to have been due to technical problems.
Volume 40 Number 6
Pulp
healing and restorative
materials
791
Pig. 1. Cavity (C) had been filled with soft carious human dentin and amalgam for 7 days and then with a corticosteroid-containing cement and amalgam for 7 days after the first filling had been removed. Irregular secondary dentin (SD) has started to form and a slight cellular infiltration is present. (Magnification, x50.) Pig. b. Higher magnification of an area at the pulp/dentin interface from Fig. 1. Note cellular inclusions in the irregular secondary dentin (SD). (Magnification, x150.) Fig. 3. Cavity (C) had heen filled with soft carious human dentin for 7 days and then with amalgam for 7 days after the first filling had been removed. Irregular secondary dentin (SD) had formed subjacent to the cavity except in one area (arrozu) where severe cellular infiltration persisted. (Magnification, x50.) Fig. 4. Pulp/dentin region in the location corresponding to the severe cellular infiltration shown in Fig. 3. No predentin or irregular secondary dentin is found corresponding to the severe cellular infiltration. (Magnification, x280.)
Oral Surg. December, 1975
Fig. 5. Pulp/dentin region subjacent to cavity which had been filled with soft carious human dentin and amalgam for 7 days and then with a corticosteroid-containing cement and amalgam for 44 days after the first filling had been removed. Note extensive secondary dentin (Li’D) formation with cellular inclusions (arrow). (Magnification, x100.) Fig. 6. Cavity (C) had been filled with soft carious human dentin for 7 days and then with amalgam for 44 days after the first filling had been removed. Secondary dentin (SD) has formed subjacent to the cavity, but severe inflammaticn persists in the pulp. (Magnification, x100.)
The pulp reactions subjacent to amalgam-covered dentin after 14 days’ observation time varied considerably. They were usually classified as slight, but teeth with severe reactions (Fig. 6) as well as those with no signs of pulp inflammation were noted. One-hundred-four-day
observation
period
(Figs. 7 to 10)
After a SO4day observation period the reactions noted in all teeth were characterized by large masses of irregular secondary dentin subjacent to the cavities. No pulp reactions were found subjacent to corticosteroid-covered dentin or in about half of the teeth with amalgam-covered dentin (Figs. 7 to 9). In the remaining teeth with amalgam-covered dentin, the pulp reactions were classified as slight (Fig. 10) and included hyperemia and a slight cellular infiltration. Large masses of irregular secondary dentin had formed subjacent to all cavities. Cellular inclusions were often present in the first-formed irregular secondary dentin, but the rest of it had a fairly uniform, tubular structure (Figs. 7 and 9). No cell-free zone was observed subjacent to the odontoblast layer bordering the masses of irregular secondary dentin, but this is often found in situations with an increased rate of irregular secondary dentin formation. The healing is considered completed at this stage (Figs. 7 to 9).
Volume 40 Number 6
Pulp
healing and restorative
materials
793
Fig. 7. Irregular secondary dentin (SD) subjacent to a cavity which had been filled with soft carious human dentin and amalgam for 7 days and then with a corticosteroid-containing cement and amalgam for 104 days after the first filling had been removed. A few cellular is found in the pulp. inclusions are seen close to the primary dentin. No inflammation (Magnification, x100.) Fig. 8. Cavity (C) had been filled with soft carious human dentin and amalgam for 7 days and then with amalgam for 104 days after the first filling had been removed. Irregular secondary dentin (SD) has formed subjacent to the cavity, and no or only very slight evidence of inflammation is found in the pulp. (Magnification, x40.)
DISCUSSION The regularity and uniformity of the response initiated by the first fillings with soft carious human dentin and amalgam are important for an assessment of the healing capacity of the materials used. Previous studies have shown that severe pulp inflammation occurs regularly with this technique, and it is considered to give reproducible responses within acceptable biologic limits.4 These observations have been confirmed by us (unpublished observations). The results from the series with 7 days’ healing also indicate that severe pulp reactions had been induced by the initial experimental procedure. In some teeth severe inflammation persisted in certain areas (Figs. 3 and 4)) while in other areas, where fairly marked healing had taken place (Figs. 1 and 2)) more irregular secondary dentin had formed than if similar restorations had been inserted in intact monkey teeth. 5, G It must be assumed, therefore, that the intended pulp inflammation had been induced by the initial experimental procedure. On this basis, it may be concluded that healing of localized pulp inflammation may occur subjacent to both corticosteroid-covered and amalgamcovered dentin, but that it occurs more slowly and with less regularity under amalgam-covered dentin. The corticosteroid-containing cement used in the present study contains
Oral Surg. l)oeeml~er, 1975
Fig. 9. liigher magnification of an area from Fig. 8. The thick layer of irregular secondary dentin (SD) has cellular inclusions fn~ozc,) close to the primary dentin. No inflammation is found in the pulp. (Magnification, x100.) Fig. 10. Irregular secondary dentin (SD) subjacent to a cavity xvhich had been filled with soft, carious human dentin and amalgam for 7 days and then mith amalgam for 104 days after the first filling had been removed. Hyperemia and a slight cellular infiltration in the pulp tissutl are seen. (Magnification, x100.)
an antibiotic and other ingredients in addition to a corticosteroid. However, this cement did not exhibit an additional healing effect when used in the present experimental s-ystem, as compared to that seen subjacent to calcium-hytlroxidecovered and zinc-oside-eugcnol-covered dentin .? In fact, the results were quite similar when these three types of cement base were used. The healing subjacent to amalgam-covered dentin was somewhat delayed in time and generally less complete as compared to the cement-covered dentin used in this and previous7 studies. The cavities used were relatively deep, that is, in the pulpal half of the dentin. Clinical experience indicates that if such cavities arc restored without a lining or base, discomfort may persist for some time. The somewhat delayed healing under amalgam-covered dentin therefore supports clinical observations. Histologic studies of the effect on the pulp following the insertion of deep, unlined restorations in intact teeth also suggest that irritation may be caused by such fillings.8* 9 CONCLUSIONS
Healing of induced pulpitis may take place subjacent to corticosteroidcovered and amalga,m-covered dentin under the present experimental conditions. Marked healing occurs within the first 7 days. The reactions subjacent to corticosteroid-covered dentin were similar to those found in response to calciumhydroxide-covered and zinc-oxide-and-eugenol-covered dentin reported previously. The healing subjacent to amalgam-covered dentin was less complete during the
Pulp
healing
and restorative
materials
795
observation periods available as compared to that subjacent to calciumhydroxide-covered, zinc-oxide-and-eugenol-covered, and corticosteroid-covered dentin used in this experimental system. These findings are considered to be in accordance with clinical experience in that more discomfort is generally experienced by patients if deep, unlined amalgam restorations are placed than if restorations with a base material are inserted. REFERENCES 1. Massler, M.: Pulp Reactions
to Dental Caries, Int. Dent. J. 17: 441-460, 1967. 2. Langeland, K. : Tissue Changes in the Dental Pulp ; an Experimental Histologic Study, Odontol. Tidskr. 65: 239-386. 1957. 3. Langeland, I?., D&den, %. ‘E.j Tronstad, L., and Langeland, L. K. : Human Pulp Changes of Iatroeenic Oriein. ORAL SURQ. 32: 943-980. 1971. 4. Mjb;r, I.-A., and-Trbnstad, L.: Experimentally Induced Pulpitis, ORAL SURG. 34: 102-108,
1972.
Materials, 5. Tronstad, L., and MjSr, I. A.: Pulp Reactions to Calcium Hydroxide-Containing ORAL SURG. 33: 961-965. 1972. 6. Erikseh, H. M.: Protective Effect of Dift’erent Lining Materials Placed Under Composite Resin Restorations in Monkeys. Stand. J. Dent. Res. 82: 373-380, 1974. 7. MjBr, I. A., and Tronstad; L.: The Healing of Experimentally Induced Pulpitis, ORAL SURG. 38: 115-121, 1974. Zinc Oxide/Eugenol and Amalgam on the 8. Mjiir, I. A.: The Effect of Calcium Hydroxide, Pulp, Odontol. Tidskr. 71: 94-105, 1963. 9. MGllcr, B., and Granath, L.-E.: Reaction of the Human Dental Pulp to Silver Amalgam Restorations, Acta Odontol. &and. 31: X37-192, 1973.
Reprint
requests
to:
Dr. Ivar A. MjBr NIOM Scandinavian Institute Forskningsveien 1 Oslo 3, Norway
of Dental
Materials