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An attempt to correlate dentin and pulp changes in human carious teeth
An attempt to correlate dentin and pulp changesin human carious teeth Ole Skogedul, D.D.S., lic.oo?ont., and Leif Ph.D., Oslo, Norway, and Malmii, Sweden DEPARTMENT OSLO,
AND
OF
OPERdTIVE
DEPARTMENT
DENTISTRY,
OF ENDODONTICS,
Tronstad,
DENTAL DENTAL
D.D.S., lic.odont.,
FACULTY, FACULTY,
UNIVERSITY
OF
UNIVERSITY
OF
LUND
The purpose of the present investigation was to study the dentin and pulp changes in the two halves of bisected carious teeth in order to determine if they are comparable. The dentin was studied by means of contact microradiography. Hypo- and hypermineralized zones, which were fairly similar in extension and degree of mineralization, were seen in the primary dentin of both halves of the teeth. If secondary dentin had formed, comparable amounts were usually present in the two halves. The pulp was studied, using demineralized 5 lrn thick paraffin serial sections. In teeth with deep carious lesions severe inflammation with abscess formation was often observed in one half, whereas only scattered inflammatory cells were present in the other half. It seems questionable, therefore, whether the study of dentin and pulp reactions to caries in different halves of bisected teeth is a suitable method in investigations eoneerning a possible correlation between these reactions.
A
n intimate relationship exists between the dentin and the dental pulp. It is therefore reasonable to expect pulpal involvement subjacent to lesions in the dentin. There is, however, great disagreement in the lit,erature on this issue. Studying the pulp of teeth with caries of the dentin, some authors report pathologic changes even under early superficial lesions.lm5 These authors describe disruption of the odontoblast layer, subodontoblastic vascular engorgement, and cellular infiltration of the affected area of the pulp. In contrast to this, other investigators describe a normal arrangement of the odontobast layer and no pulpal inflammation under much deeper and presumably more destructive lesions6-* It is conceivable that the apparent discrepancies in the findings of these studies are due to variations in the reaction known to occur in the dentin subjacent to carious lesions.g-12 If earious teeth are bisected, ground sections may be prepared from one half of the tooth and demineralized sections from the other half. This method permits 135
136
Xkogedal mad Tronstad
Oral January,
Surg. 1977
Fig. 1. Microradiograph showing carious lesion in the dentin of two ground sections from bisected molar. Hypo- and hypermineralized zones which are comparable in extension and degree of mineralization are seen in the dentin of both sections. (Magnification, x10.)
the study of the mineral phase of the dentin and the morphology of the pulp of the same tooth and has been used in attempts to correlate the dentinal and pulpal changes in carious teeth.?9 I3 However, before one draws conclusions from such a study, it seems imperative to establish whether the reactions in the dentin and in the pulp of the two halves of the teeth are comparable in a sufficient number of instances, It was the purpose of the present study, therefore, to carry out such comparative studies of the dentin and the pulp of the two halves of carious teeth split longitudinally through the carious lesion and the pulp. MATERIALS AND METHODS The experimental material comprised forty-eight human carious teeth extracted for various reasons. From twenty teeth two longitudinal slices were cut with a diamond disk of 300 pm thickness through the deepest part of the carious lesion and the pulp, by means of a Bronwill thin-sectioning machine, model 60. The slices were reduced in thickness from about 200 pm to about 80 pm by grinding on abrasive papers. Contact microradiographs of the ground sections were then produced on Kodak Spectroscopic plates 649-O with a Phillips x-ray diffraction unit, type PW 1009, equipped with a fine focus tube. Nickel-filtered copper radiation at 20 kv. and 20 Ma. was employed, and the target-film distance was 26 cm. The plates were developed in Kodak D-11 under constant agitation. This technique has been shown to demonstrate the distribution of minerals in dental tissues.l* The microradiographs of the two ground sections of each tooth, which during exposure had been placed close together on the same plate, were then examined and compared in the light microscope. Special attention was paid to the zones of hypo- and hypermineralization12 and a possible deposition of secondary dentin. After fixation in 10 per cent neutral-buffered formalin, twenty-eight teeth were split in a longitudinal direction through the macroscopically deepest part of the carious lesion and the pulp by means of a Bronwill thin-sectioning machine.
Volume 43 Number 1
Dentin
and pulp changes in carious teeth
137
Figs. d and PI. Demineralized sections from two halves of bisected molar with deep carious lesion. In one half of the tooth (Fig. 2) a severe inflammatory reaction with abscess formation is seen. In the other half (Fig. 3) only scattered inflammatory cells are present. (Hematoxylin and eosin stain. Magnification, x40.)
Table I. Comparison of dentinal reactions in the two halves of bisected carious teeth as studied by microradiography Correlation Hypomineralized zone 15
between halves of teeth
Hypermineralized zone 14
The divided teeth were demineralized in 5.2 per cent nitric acid and serially sectioned at 5 pm parallel with the cut surfaces. The sections were stained with hematoxylin and eosin, or according to the Brown and Brenn method for the demonstration of bacteria, and they were examined and compared in the light microscope. The pulp responses were classified as no/slight, moderate, or severe.3’ l5 According to the deepest penetration of bacteria to the superficial, middle, or pulpal third of the dentin, the carious lesions were classified as superficial, moderately deep, or deep. RESULTS Dentinal reactions
The results are presented in Table I. Hypo- and hypermineralized zones were observed in the dentin subjacent to the carious lesion in all ground sections, and both types of zones were comparable in thirteen teeth (Fig. 1). The hy-
Oral January,
138
Skogedal and Tromtad
Table
II. Comparison of pulp reactions in the two halves of bisected teeth
Surg. 1977
No. of teeth (n = 28)
Degree ofpulp reaction in two halves of teeth
18
No/slight and no/slight Moderate and moderate Severe and severe Correlated reaction No/slight and moderate No/slight and severe Moderate and severe Different reaction
-i 21 2 4 I -7
Ill. Comparison of pulp reactions in the two halves of bisected carious teeth as related to cavity depth
Table
Curious penetration No. of teeth (28)
Correlated reaction Different reaction
21 7
Tos;
erer’ R.
2
of primary
dentin
To middle third
8
Tolf,;$~
II 7
pomineralized zones were comparable in another two teeth, and the hypermineralized zones in one additional tooth. In the remaining teeth, especially the width of the zones varied between the two ground sections studied. Comparable amounts of secondary dentin were deposited in the two halves of nine teeth, whereas in eight teeth no secondary dentin had formed. Pulpal
reactions
The results are presented in Tables II and III. In the two halves of twentyone of twenty-eight teeth the pulp reactions were comparable. In eighteen of the teeth where a correlation was found, the pulp was almost devoid of inflammatory cells. A moderate reaction was observed in both halves of one tooth, whereas a severe inflammatory reaction was seen in the two halves of two teeth (Table II). Different reactions were observed in the two halves of seven teeth. In four of the teeth a severe inflammatory response was found in one half (Fig. 2)) whereas only scattered inflammatory cells were seen in the other half (Fig. 3). In the remaining three teeth, a moderate versus a severe or slight reaction was found in the two halves (Table II). The bacteria had penetrated less than two thirds of the primary dentin in ten teeth (Table III). The pulp of these teeth was almost devoid of inflammatory cells and the reactions in the pulp of the two halves of these teeth were comparable. Eighteen teeth exhibited deep carious lesions, and pulpal inflammation was observed in sections from both halves in ten teeth. In seven of these teeth the pulp reaction was not comparable from one half of the tooth to the other (Table II).
Volume Number
43 1
Dentin
and pulp changes &IL curious teeth
139
DISCUSSION
The reaction in the dentin of carious teeth as studied by microradiography appears to be fairly uniform under the deepest parts of the lesion. Thus, in the present study a good correlation was found between the degree and pattern of mineralization in ground sections made from the two halves of bisected teeth. It should be borne in mind, however, that microradiography is a relatively coarse technique. Structural superimpositions are probably unavoidable in sections of 80 pm thickness and may at least partly account for the observed similarity in the reactions. When the reactions in the pulp of the two halves of the bisected teeth were compared, great differences were sometimes observed. Still, comparable puln reactions were observed in the halves of teeth with superficial or moderately deep carious lesions. Only negligible signs of inflammation were seen in the pulp of these teeth. However, the teeth were bisected with a 300 pm thick disk, and at least 400 to 700 pm of the pulp tissue subjacent to the deepest part of the carious lesion was necessarily lost before sections could be obtained from the two halves of the teeth. Foci of inflammatory cells might therefore also be partly or completely lost in this region of the pulp. It should also be noted that although the teeth macroscopically appeared to be divided through the deepest part of the lesion, microscopic discrepancies may exist in the carious penetration of the two halves (Figs. 2 and 3). When the carious process has reached the pulpal third of the dentin, such discrepancies apparently may be crucial. Thus, in teeth with deep carious lesions and severe pulpal inflammation the correlation between the reaction in the two halves of the teeth was usually bad. It seems likely, therefore, that the present methods are not suitable in correlating dentinal and pulpal reactions to caries as has been reported.‘, l3 Furthermore it should be remembered that the dentinal reaction to caries regularly was comparable in the two halves of bisected teeth, whereas the pulpal response usually was different in the two halves when a severe inflammation was observed. These findings indicate that the state of the pulp of carious teeth is not closely correlated with the degree of mineralization of the overlying dentin as observed in microradiographs. REFERENCES
1. Nygaard-iistby, 2. r6yb;;ri H.:
B.: Caries Profunda, Nor. Tannlaegeforen. Tid. 61: 96-105; 1956. Healing Processes in the Pulp on Capping, Acta Odontol. &and. 13: Supp.
3. Ls&geland, K.: Tissue Changes in the Dental Pulp, Odontol. Tidskr. 65: 239-386, 1957. 4. Langeland, Ii.: Pulpal Response to Caries and Operative Procedures, J. Dent. Assoc. 8. Afr. 18: 101-112, 1963. 5. BrLnnstrSm, M., and Lind, P. 0.: Pulpal Response to Early Dental Caries, J. Dent. Res. 44: 10451050, 1965. 6. MacGregor, A., Marsland, E. A., and Batty, I.: Experimental Studies of Dental Caries. I. The Relation of Bacterial Invasion to Softening of the Dentine, Br. Dent. J. 101: 230235, 1956. 7. Kuwabara, R. K., and Massler, M.: Pulpal Reactions to Active and Arrested Carious Lesions, J. Dent. Child. 33: 190-204, 1966. 8. Shovelton, D. 8.: A Study of Deep Carious Dentine, Int. Dent. J. 18: 392-405, 1968. 9. Bodecker, C. F.: Tooth Condition, a Factor in Experimental Isotope Absorption, J. Dent. Res. 22: 281-285, 1943. 10. Dreyfuss, F., Frank, R. M., and Gutmann, B.: La S&rose Dentinaire, Bull. Group. Int. Rech. Sci. Stomatol. 7: 207-229, 1964.
140
Skogedal
rind
Trmstnd
Oral
Surg.
Januzwy,
1977
11. Frank, R. M., Wolff, F., and Gutmann, B. : Mciroscopie Electronique de la Carie au Niveau de la Dentine Humaine, Arch. Oral Biol. 9: 163-179, 1964. 12. Takuma! S., Hunohara, H., Sekiguchi, K., and Egawa, I.: Electron Microscopy of Carious Lesions m Human Dentin, Bull. Tokyo Dent. Coll. 8: 143-165, 1967. 13. Baume, L. J.: Dental Pulp Conditions in Relation to Carious Lesions, Int. Dent. J. 20: 309337, 1970. 14. Bergman, G., and Engfeldt, B.: Studies on Mineralized Dental Tissues. IT. Microradiography as a Method for Studying Dental Tissues and Its Application to the Study of Caries, Acta Odontol. &and. 12: 99-132, 1954. 15. Mjijr, I. A., and Tronstad, L.: Experimentally Induced Pulpitis, ORAL SURG. 34: 102-108, 1972. Reprint
requests
to:
Dr. Ole Skogedal Department of Operative Dental Faculty University of Oslo Geitmyrsv. 71 Oslo 4, Norway
Dentistry
AND
OF
OPERdTIVE
DEPARTMENT
DENTISTRY,
OF ENDODONTICS,
Tronstad,
DENTAL DENTAL
D.D.S., lic.odont.,
FACULTY, FACULTY,
UNIVERSITY
OF
UNIVERSITY
OF
LUND
The purpose of the present investigation was to study the dentin and pulp changes in the two halves of bisected carious teeth in order to determine if they are comparable. The dentin was studied by means of contact microradiography. Hypo- and hypermineralized zones, which were fairly similar in extension and degree of mineralization, were seen in the primary dentin of both halves of the teeth. If secondary dentin had formed, comparable amounts were usually present in the two halves. The pulp was studied, using demineralized 5 lrn thick paraffin serial sections. In teeth with deep carious lesions severe inflammation with abscess formation was often observed in one half, whereas only scattered inflammatory cells were present in the other half. It seems questionable, therefore, whether the study of dentin and pulp reactions to caries in different halves of bisected teeth is a suitable method in investigations eoneerning a possible correlation between these reactions.
A
n intimate relationship exists between the dentin and the dental pulp. It is therefore reasonable to expect pulpal involvement subjacent to lesions in the dentin. There is, however, great disagreement in the lit,erature on this issue. Studying the pulp of teeth with caries of the dentin, some authors report pathologic changes even under early superficial lesions.lm5 These authors describe disruption of the odontoblast layer, subodontoblastic vascular engorgement, and cellular infiltration of the affected area of the pulp. In contrast to this, other investigators describe a normal arrangement of the odontobast layer and no pulpal inflammation under much deeper and presumably more destructive lesions6-* It is conceivable that the apparent discrepancies in the findings of these studies are due to variations in the reaction known to occur in the dentin subjacent to carious lesions.g-12 If earious teeth are bisected, ground sections may be prepared from one half of the tooth and demineralized sections from the other half. This method permits 135
136
Xkogedal mad Tronstad
Oral January,
Surg. 1977
Fig. 1. Microradiograph showing carious lesion in the dentin of two ground sections from bisected molar. Hypo- and hypermineralized zones which are comparable in extension and degree of mineralization are seen in the dentin of both sections. (Magnification, x10.)
the study of the mineral phase of the dentin and the morphology of the pulp of the same tooth and has been used in attempts to correlate the dentinal and pulpal changes in carious teeth.?9 I3 However, before one draws conclusions from such a study, it seems imperative to establish whether the reactions in the dentin and in the pulp of the two halves of the teeth are comparable in a sufficient number of instances, It was the purpose of the present study, therefore, to carry out such comparative studies of the dentin and the pulp of the two halves of carious teeth split longitudinally through the carious lesion and the pulp. MATERIALS AND METHODS The experimental material comprised forty-eight human carious teeth extracted for various reasons. From twenty teeth two longitudinal slices were cut with a diamond disk of 300 pm thickness through the deepest part of the carious lesion and the pulp, by means of a Bronwill thin-sectioning machine, model 60. The slices were reduced in thickness from about 200 pm to about 80 pm by grinding on abrasive papers. Contact microradiographs of the ground sections were then produced on Kodak Spectroscopic plates 649-O with a Phillips x-ray diffraction unit, type PW 1009, equipped with a fine focus tube. Nickel-filtered copper radiation at 20 kv. and 20 Ma. was employed, and the target-film distance was 26 cm. The plates were developed in Kodak D-11 under constant agitation. This technique has been shown to demonstrate the distribution of minerals in dental tissues.l* The microradiographs of the two ground sections of each tooth, which during exposure had been placed close together on the same plate, were then examined and compared in the light microscope. Special attention was paid to the zones of hypo- and hypermineralization12 and a possible deposition of secondary dentin. After fixation in 10 per cent neutral-buffered formalin, twenty-eight teeth were split in a longitudinal direction through the macroscopically deepest part of the carious lesion and the pulp by means of a Bronwill thin-sectioning machine.
Volume 43 Number 1
Dentin
and pulp changes in carious teeth
137
Figs. d and PI. Demineralized sections from two halves of bisected molar with deep carious lesion. In one half of the tooth (Fig. 2) a severe inflammatory reaction with abscess formation is seen. In the other half (Fig. 3) only scattered inflammatory cells are present. (Hematoxylin and eosin stain. Magnification, x40.)
Table I. Comparison of dentinal reactions in the two halves of bisected carious teeth as studied by microradiography Correlation Hypomineralized zone 15
between halves of teeth
Hypermineralized zone 14
The divided teeth were demineralized in 5.2 per cent nitric acid and serially sectioned at 5 pm parallel with the cut surfaces. The sections were stained with hematoxylin and eosin, or according to the Brown and Brenn method for the demonstration of bacteria, and they were examined and compared in the light microscope. The pulp responses were classified as no/slight, moderate, or severe.3’ l5 According to the deepest penetration of bacteria to the superficial, middle, or pulpal third of the dentin, the carious lesions were classified as superficial, moderately deep, or deep. RESULTS Dentinal reactions
The results are presented in Table I. Hypo- and hypermineralized zones were observed in the dentin subjacent to the carious lesion in all ground sections, and both types of zones were comparable in thirteen teeth (Fig. 1). The hy-
Oral January,
138
Skogedal and Tromtad
Table
II. Comparison of pulp reactions in the two halves of bisected teeth
Surg. 1977
No. of teeth (n = 28)
Degree ofpulp reaction in two halves of teeth
18
No/slight and no/slight Moderate and moderate Severe and severe Correlated reaction No/slight and moderate No/slight and severe Moderate and severe Different reaction
-i 21 2 4 I -7
Ill. Comparison of pulp reactions in the two halves of bisected carious teeth as related to cavity depth
Table
Curious penetration No. of teeth (28)
Correlated reaction Different reaction
21 7
Tos;
erer’ R.
2
of primary
dentin
To middle third
8
Tolf,;$~
II 7
pomineralized zones were comparable in another two teeth, and the hypermineralized zones in one additional tooth. In the remaining teeth, especially the width of the zones varied between the two ground sections studied. Comparable amounts of secondary dentin were deposited in the two halves of nine teeth, whereas in eight teeth no secondary dentin had formed. Pulpal
reactions
The results are presented in Tables II and III. In the two halves of twentyone of twenty-eight teeth the pulp reactions were comparable. In eighteen of the teeth where a correlation was found, the pulp was almost devoid of inflammatory cells. A moderate reaction was observed in both halves of one tooth, whereas a severe inflammatory reaction was seen in the two halves of two teeth (Table II). Different reactions were observed in the two halves of seven teeth. In four of the teeth a severe inflammatory response was found in one half (Fig. 2)) whereas only scattered inflammatory cells were seen in the other half (Fig. 3). In the remaining three teeth, a moderate versus a severe or slight reaction was found in the two halves (Table II). The bacteria had penetrated less than two thirds of the primary dentin in ten teeth (Table III). The pulp of these teeth was almost devoid of inflammatory cells and the reactions in the pulp of the two halves of these teeth were comparable. Eighteen teeth exhibited deep carious lesions, and pulpal inflammation was observed in sections from both halves in ten teeth. In seven of these teeth the pulp reaction was not comparable from one half of the tooth to the other (Table II).
Volume Number
43 1
Dentin
and pulp changes &IL curious teeth
139
DISCUSSION
The reaction in the dentin of carious teeth as studied by microradiography appears to be fairly uniform under the deepest parts of the lesion. Thus, in the present study a good correlation was found between the degree and pattern of mineralization in ground sections made from the two halves of bisected teeth. It should be borne in mind, however, that microradiography is a relatively coarse technique. Structural superimpositions are probably unavoidable in sections of 80 pm thickness and may at least partly account for the observed similarity in the reactions. When the reactions in the pulp of the two halves of the bisected teeth were compared, great differences were sometimes observed. Still, comparable puln reactions were observed in the halves of teeth with superficial or moderately deep carious lesions. Only negligible signs of inflammation were seen in the pulp of these teeth. However, the teeth were bisected with a 300 pm thick disk, and at least 400 to 700 pm of the pulp tissue subjacent to the deepest part of the carious lesion was necessarily lost before sections could be obtained from the two halves of the teeth. Foci of inflammatory cells might therefore also be partly or completely lost in this region of the pulp. It should also be noted that although the teeth macroscopically appeared to be divided through the deepest part of the lesion, microscopic discrepancies may exist in the carious penetration of the two halves (Figs. 2 and 3). When the carious process has reached the pulpal third of the dentin, such discrepancies apparently may be crucial. Thus, in teeth with deep carious lesions and severe pulpal inflammation the correlation between the reaction in the two halves of the teeth was usually bad. It seems likely, therefore, that the present methods are not suitable in correlating dentinal and pulpal reactions to caries as has been reported.‘, l3 Furthermore it should be remembered that the dentinal reaction to caries regularly was comparable in the two halves of bisected teeth, whereas the pulpal response usually was different in the two halves when a severe inflammation was observed. These findings indicate that the state of the pulp of carious teeth is not closely correlated with the degree of mineralization of the overlying dentin as observed in microradiographs. REFERENCES
1. Nygaard-iistby, 2. r6yb;;ri H.:
B.: Caries Profunda, Nor. Tannlaegeforen. Tid. 61: 96-105; 1956. Healing Processes in the Pulp on Capping, Acta Odontol. &and. 13: Supp.
3. Ls&geland, K.: Tissue Changes in the Dental Pulp, Odontol. Tidskr. 65: 239-386, 1957. 4. Langeland, Ii.: Pulpal Response to Caries and Operative Procedures, J. Dent. Assoc. 8. Afr. 18: 101-112, 1963. 5. BrLnnstrSm, M., and Lind, P. 0.: Pulpal Response to Early Dental Caries, J. Dent. Res. 44: 10451050, 1965. 6. MacGregor, A., Marsland, E. A., and Batty, I.: Experimental Studies of Dental Caries. I. The Relation of Bacterial Invasion to Softening of the Dentine, Br. Dent. J. 101: 230235, 1956. 7. Kuwabara, R. K., and Massler, M.: Pulpal Reactions to Active and Arrested Carious Lesions, J. Dent. Child. 33: 190-204, 1966. 8. Shovelton, D. 8.: A Study of Deep Carious Dentine, Int. Dent. J. 18: 392-405, 1968. 9. Bodecker, C. F.: Tooth Condition, a Factor in Experimental Isotope Absorption, J. Dent. Res. 22: 281-285, 1943. 10. Dreyfuss, F., Frank, R. M., and Gutmann, B.: La S&rose Dentinaire, Bull. Group. Int. Rech. Sci. Stomatol. 7: 207-229, 1964.
140
Skogedal
rind
Trmstnd
Oral
Surg.
Januzwy,
1977
11. Frank, R. M., Wolff, F., and Gutmann, B. : Mciroscopie Electronique de la Carie au Niveau de la Dentine Humaine, Arch. Oral Biol. 9: 163-179, 1964. 12. Takuma! S., Hunohara, H., Sekiguchi, K., and Egawa, I.: Electron Microscopy of Carious Lesions m Human Dentin, Bull. Tokyo Dent. Coll. 8: 143-165, 1967. 13. Baume, L. J.: Dental Pulp Conditions in Relation to Carious Lesions, Int. Dent. J. 20: 309337, 1970. 14. Bergman, G., and Engfeldt, B.: Studies on Mineralized Dental Tissues. IT. Microradiography as a Method for Studying Dental Tissues and Its Application to the Study of Caries, Acta Odontol. &and. 12: 99-132, 1954. 15. Mjijr, I. A., and Tronstad, L.: Experimentally Induced Pulpitis, ORAL SURG. 34: 102-108, 1972. Reprint
requests
to:
Dr. Ole Skogedal Department of Operative Dental Faculty University of Oslo Geitmyrsv. 71 Oslo 4, Norway
Dentistry