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Penetration by Dyes of Normal Cementum of Permanent Teeth
D IA G N O S IS O F F O C A L IN F E C T IO N . . . V O L U M E 42, J U N E 1951 • 637
A N A T O M IC C O N SID E R ATIO N S P E N E T R A T IO N B Y D Y E S O F N O R M A L CEM ENTUM
OF PERM ANEN T TEETH
In an attempt to evaluate the ability of cementum to protect the root from in vasion by microorganisms and toxic prod ucts, or to protect the host from the dis semination o f bacteria and toxic products from the root canal, probably one should recall briefly the morphology of this bone like substance and the morphology of the apex o f the root. Kotanyi20 states: Acellular cementum covers the root dentin from the cementoenamel junction to the apex. It is thinnest at the cementoenamel junction (20 to 50 m icrons) and thickest toward the apex (150 to 200 m icrons). T h e apical for amen is surrounded by cementum. Sometimes the cementum extends to the inner wall o f the dentin for a short distance in the root canal, form ing a lining. Both acellular and cellular cementum are lam ellated; the incremental lines, dividing the lamellae, indicate periodic formation . . . .
Coolidge21 pointed out in 1929: The main canal may have branches with other foramina, which probably contain similar tis sue. T h e dentino-cemental junction is an ex tremely variable point at the orifice o f the canal. In some teeth the cementum forms the foram en and, in others, it does not. It would seem that the success o f a root-canal filling does not depend on the removal of the pulp to any definite point, but it should be ampu tated close to the apical foramen. Curved canals, inaccessible branches of the main canal and roots containing calcifications offer in creased difficulties to root-canal operations, but such difficulties do not seem to prevent suc cessful results if all infection is destroyed within the remaining tissue and the canal care fully filled to the surface o f the pulp stump.
In 1931, after a microscopic study o f a very large series of sections, he pointed out further:22 “ Comparative studies of the roots of young and old individuals have given positive evidence o f the continuous increase in thickness of the cementum de posited in successive layers one upon the other during the life cycle of the tooth. The roots of the teeth o f old individuals
generally show many layers of cementum laid down in thin lamellae parallel to the root surface.” Calling attention to the difference in the behavior o f cemen tum and bone, he continues, “ the ce mentum is a bonelike substance that is not physiologically resorbed.” As early as 1920 Davis23 pointed out the walling-off activity of cementum fol lowing the removal of a vital pulp from the root canal of a tooth: “ I have examined over one hundred cases, made sections, and mounted them for permanent evidence. I have many cases wherein the pulp-canal filling fell short of the apex from 1 to 3 mm., and where the remaining portion of the canal had been filled with cementum or dentin or calcic matter, separate or in combina tion, so that there existed no opening to the canal at the time of extraction. This has taken place both in cases of single and multiple foramina.” Rickert,24 in 1927, performed an experi ment to test the permeability of the roots o f teeth. He found, when the root canal contents had been removed from freshly extracted teeth, that a 10 per cent solu tion o f silver nitrate could not penetrate through normal cementum into the den tin except at the apical portion. If, how ever, the apical third of the canal of a freshly extracted tooth were filled care fully with a satisfactory adhesive root filling and the tooth placed in the 10 per cent solution of silver nitrate, the silver would fail to penetrate the cementum to a greater extent in the apical portion than in the gingival portion. D E N T IC L E S IN D IC A T IO N
IN
ROOT
CANAL
O F IN F E C T E D
AS
PULP
Orban,25 in his textbook, describes pulp nodules or denticles as formations on the borderline of pathologic conditions. He states: “ Pulp stones often are found in teeth which appear to be quite normal in
A N A T O M IC C O N SID E R ATIO N S P E N E T R A T IO N B Y D Y E S O F N O R M A L CEM ENTUM
OF PERM ANEN T TEETH
In an attempt to evaluate the ability of cementum to protect the root from in vasion by microorganisms and toxic prod ucts, or to protect the host from the dis semination o f bacteria and toxic products from the root canal, probably one should recall briefly the morphology of this bone like substance and the morphology of the apex o f the root. Kotanyi20 states: Acellular cementum covers the root dentin from the cementoenamel junction to the apex. It is thinnest at the cementoenamel junction (20 to 50 m icrons) and thickest toward the apex (150 to 200 m icrons). T h e apical for amen is surrounded by cementum. Sometimes the cementum extends to the inner wall o f the dentin for a short distance in the root canal, form ing a lining. Both acellular and cellular cementum are lam ellated; the incremental lines, dividing the lamellae, indicate periodic formation . . . .
Coolidge21 pointed out in 1929: The main canal may have branches with other foramina, which probably contain similar tis sue. T h e dentino-cemental junction is an ex tremely variable point at the orifice o f the canal. In some teeth the cementum forms the foram en and, in others, it does not. It would seem that the success o f a root-canal filling does not depend on the removal of the pulp to any definite point, but it should be ampu tated close to the apical foramen. Curved canals, inaccessible branches of the main canal and roots containing calcifications offer in creased difficulties to root-canal operations, but such difficulties do not seem to prevent suc cessful results if all infection is destroyed within the remaining tissue and the canal care fully filled to the surface o f the pulp stump.
In 1931, after a microscopic study o f a very large series of sections, he pointed out further:22 “ Comparative studies of the roots of young and old individuals have given positive evidence o f the continuous increase in thickness of the cementum de posited in successive layers one upon the other during the life cycle of the tooth. The roots of the teeth o f old individuals
generally show many layers of cementum laid down in thin lamellae parallel to the root surface.” Calling attention to the difference in the behavior o f cemen tum and bone, he continues, “ the ce mentum is a bonelike substance that is not physiologically resorbed.” As early as 1920 Davis23 pointed out the walling-off activity of cementum fol lowing the removal of a vital pulp from the root canal of a tooth: “ I have examined over one hundred cases, made sections, and mounted them for permanent evidence. I have many cases wherein the pulp-canal filling fell short of the apex from 1 to 3 mm., and where the remaining portion of the canal had been filled with cementum or dentin or calcic matter, separate or in combina tion, so that there existed no opening to the canal at the time of extraction. This has taken place both in cases of single and multiple foramina.” Rickert,24 in 1927, performed an experi ment to test the permeability of the roots o f teeth. He found, when the root canal contents had been removed from freshly extracted teeth, that a 10 per cent solu tion o f silver nitrate could not penetrate through normal cementum into the den tin except at the apical portion. If, how ever, the apical third of the canal of a freshly extracted tooth were filled care fully with a satisfactory adhesive root filling and the tooth placed in the 10 per cent solution of silver nitrate, the silver would fail to penetrate the cementum to a greater extent in the apical portion than in the gingival portion. D E N T IC L E S IN D IC A T IO N
IN
ROOT
CANAL
O F IN F E C T E D
AS
PULP
Orban,25 in his textbook, describes pulp nodules or denticles as formations on the borderline of pathologic conditions. He states: “ Pulp stones often are found in teeth which appear to be quite normal in