SCIENTIFIC ARTICLES
D i f f e r e n t i a l d i a g n o s i s of i n t e r n a l a n d e x t e r n a l root r e s o r p t i o n Arnold H. G~t,,er, DDS; Thomas Mack, DDS: Richard Ca. Someflott, DDS: and Lawrence C. Walsh, DDS, Detroit
A n effort h a s b e e n m a d e to arrive at a p r e d i c t a b l e m e t h o d for correctly differentiatinq internal a n d external root resorption. The criteria for the differential diaqn o s i s a r e presented.
terizing internal resorption and suggested that certain cases require endodontic intervention and surgical repair. Lepp 9 distinguished between centrifugal, symmetric resorption beginning in the pulp chamber, and centripetal, asymmetric resorption beginning in the periodontium.
DIFFERENTIAL DIAGNOSIS Internal and external resorption have been identified as discrete entitiesA ,2 Radiographic interpretation of these lesions is of paramount importance in determining a modality of treatment and in establishing a prognosis. However, there appears to be no routine method of differentiating these two resorptive processes radiographically, z The purpose of this paper is to establish guidelines leading to a systematic approach for the differential diagnosis of internal and external root resorption. Bell 4 first reported on internal resorption in 1830. FothergilP referred to the condition as "pink spot." In 1920, Mummery 6 published the first extensive study of pink spots, and Pritchard 7 later showed histologically that internal resorption is comparable to a granuloma of the pulp. Munch, s in 1937, was the first to point out that internal resorption can often be delineated radiographically. He established the factors charac-
The basis of any attempt to establish a systematic approach toward a differential diagnosis rests on the ability to interpret normal tooth structures radiographically. Entities that must be considered are the normal tooth with its variations, dental caries, early pulpal death or incomplete root formation, internal resorption, and external resorption (see Table). To simplify the establishment of a differential diagnosis, the tooth is divided into three areas--apical, midroot, and coronal. Apical In the apical area, early pulpal death or incomplete root formation (Fig 1, top) and external resorption (Fig 1, bottom) may each show a blunted or shortened root with an open foramen. However, these conditions may be differentiated by the shape and size of the canal system and the appearance of the apex. With
early pulpal death or incomplete root formation, the canal system is large with parallel or divergent walls, and the apex may be blunderbuss in appearance. This contrasts with apical external resorption where the canal size will generally be smaller, and the walls will converge apically. The fact that orthodontic movement can cause external root resorption is well documented. 10,1t In most cases this resorption occurs at the apex and can be clearly seen radiographically (Fig 1, bottom).
Mid.root Internal and external resorption can occur on any surface of the tooth that contacts vital tissue. The margins of an internal resorptive lesion are sharp, smooth, and clearly defined (Fig 2) .2,12 Most internal resorptive lesions are symmetrical but may occur eccentrically, while external resorptions are not symmetrical and may occur on any external surface of the root. Within the margins of the lesion, internal resorption will show a defect that appears to be uniform in density. In contrast to this, external resorption, within its less well-defined margins, shows variations in density that may appear striated. This results from varying rates of resorption and repair, thus presenting a "moth-eaten" appearance. ~3
329
JOURNAL OF ENDODONTICS 1 VOL 2, NO 1I, NOVEMBER 1979
.
.
.
.
.
.
.
,
9
9
~2::: iiL,~n','~ ;:~:' i::" ~:~,,.;:~ i-~ :,~:.s,~.~:~'t(i-
::~:~ ~:;o~;;~ ;:~!'i,. . . . . . . .
. : 9 ~:
:?", ?A_I~x ~aortened, flattened, blunted, or square
:.:s
' : : ~: Marg~msof lesion are ragged and irregular i:~~ : m a y l ~ S U l ~ r ~ m p o s e d : o v e r canal
Because external resorption can occur on any lateral surface of the root, it may appear superimposed over the root canal system, presenting a difficult diagnostic problem. The shape of the root canal system can often lead to an accurate differential diagnosis. In external resorption, even though the lesion may be superimposed over the canal, the canal can be followed unaltered through the area of the defeet. In contrast to this, in internal resorption the unaltered canal or chamber cannot be followed through the lesion (Fig 3). The walls of the root canal system appear to balloon out, showing an enlarged area of uniform
330
9 Radiographic, appearance
density. There are no radiographic criteria to aid in ascertaining whether or not a perforation has occurred, regardless of the nature of the lesion. A n important radiographic aid that may be used to help distinguish these lesions can be referred to as the mesial-buccal-distal ( M B D ) rule. This rule is often applied during endodontic therapy to determine the relative position of roots. Two radiographs are exposed: one perpendicular to the tooth, the other from an angle mesial to the perpendicular in the same horizontal plane. Objects c l o s e r to the source of radiation will shift distally in relation to objects further from the source.
Fig 1--Radiographs show apical conditions." top, early pulpal death; bottom, external resorption.
JOURNAL OF ENDODONTICS
VOL 2, NO 11, NOVEMBER 1976
/
Fig 2--Radiographs show examples of internal and external resorption: top left, external resorption; top right, external resorption; bottom left, internal resorption; bottom right, internal resorption.
Fig 3----Diagrammatic representations of midroot resorptive lesions (Based on drawings by Leppg). Top, internal resorption: normal outline of canal cannot be followed through lesion; bottom, external resorption: normal outline of canal can be followed through lesion. 331
JOURNAL OF ENDODONTICS
In the context of this paper, the MBD rule may be applied in two ways. The first is to help in the differential diagnosis of internal resorption from external resorption. If the lesion is one of external resorption, it will shift from its superimposed position over the canal system on t h e mesially angulated radiograph (Fig 4, top left and right). Internal resorptive lesions, however, will not shift no matter how severe an angle the radiograph was taken from, although their shape may change (Fig 4, bottom left and right). Of course, circumstances may dictate a need to expose the angulated radiograph from the distal rather than from the mesial. This was the case in the two situations shown in Figure 4. The second use is to determine the relative position on the lateral root surface, should the lesion prove to be external resorption. If the lesion is located on or toward the palatal aspect, the mesially angulated radiograph will show it shifted to the mesial. This information is essential if surgery is indicated. A final consideration in the midroot area is the differential diagnosis between caries, external resorption, and internal resorption (Fig 5). This may become necessary because periodontally involved teeth often show midroot caries. Caries may easily be differentiated from internal resorption by the fact that, as in external resorption, the unaltered canal configuration can be followed through the area of the lesion. The outline of a carious lesion is more poorly defined than internal resorption. A difficult diagnostic problem is distinguishing midroot caries from external resorption radiographically. External resorption may show the classic striations within the margins of the lesion, whereas midroot caries usually does not. Therefore, a thorough clinical examination is always indicated.
332
VOL 2, NO 11, NOVEMBER 1979
Fig 4--Radiographs show use of MBD rule for differential diagnosis. Top left: external resorption, perpendicular; top right: external resorption, mesial; bottom le[t: internal resorption, perpendicular; bottom right: internal resorption, mesial.
JOURNAL OF ENDODONTICS
VOL 2, NO 11, NOVEMBER 1976
b: I Fig 5---Radiographs show three conditions that may be seen at level o/ alveolar crest: top left, external resorption; top right, dental caries; bottom left, internal resorption (lateral incisor).
Coronal
Internal resorption, external resorption, and caries can all occur in the coronal area of the tooth. Because vital tissue is necessary for either external or internal resorption to occur,
internal resorption can begin within the clinical crown whereas external resorption will not. However, external resorption m a y begin below the epithelial attachment, and once having penetrated the dentin, may extend incisally or occlusally to invade the clinical crown. In diagnosing these lesions in the coronal area, the same approach can be used as in the midroot section. Dental caries, as seen in Figure 5, top right, is usually located in the coronal aspect of the tooth. Caries can cause varying radiographic appearances, depending on location, and usually can be diagnosed by clinical examination. With internal resorption (Fig 2, bottom left) the canal or chamber
Fig 6--Radiographs show external resorption: top, apical; bottom, midroot.
shows an enlarged area that can vary considerably in size and location. The margins of the lesion may be sharp, smooth, and clearly defined. The lesion may be symmetrical or eccentric in nature. The normal canal outline cannot be followed through the lesion. External resorption can affect either the apex or the body of the root (Fig 6). If the resorption occurs at the 333
JOURNAL OF ENDODONTICS [ VOL 2, NO 11, NOVEMBER 1976
apex, the apex will appear shortened, blunted, or irregular in appearance. The foramen is visible in the apical region, and the opening of the canal can be seen. Assuming the tooth is mature, the walls of the root canal system converge apically. When external resorption occurs in the body of the root, the margins of the lesion are ragged and irregular. The lesion may be superimposed over the root canal, yet the normal unaltered canal outline can be followed through the region of the resorptive defect. 2 SUMMARY
AND CONCLUSIONS
Internal and external resorption can be differentially diagnosed by radiographs in most cases. In attempting to diagnose resorption, dental caries, external resorption, and internal resorption must be considered. The radiographic criteria for diagnosing these entities are presented along with the use of the MBD rule. Radiographs do not show whether or not the lesion has perforated the root. The methodology presented here provides the practitioner with a guide to identify predictably the particular
334
entity present, which enables him to establish a diagnosis and prognosis more readily, and to institute appropriate treatment. This paper is based on a table clinic that won the award of the best table clinic by graduate students at the annual scientific session of the American Association of Endodontists, New Orleans, 1975. The authors thank Mr. Eric Jacobs and Drs. Robert Hershey, Richard DeFillipo, Carl Botvinick, and Anthony Dietz for their help in completion of this paper. Drs. Gartner and Somerlott, formerly graduate students, are instructors in endodontics, and Drs. Mack and Walsh are former graduate students in endodontics, University of Detroit School of Dentistry. Requests for reprints should be directed to: Dr. Arnold H. Gar,tner, University of Detroit School of Dentistry, Department of Endodontics, 2985 E Jefferson Ave, Detroit, 48207. References
1. Rabinowitch, B.Z. Internal resorption. Oral Surg 33:263 Feb 1972. 2. Worth, H.M. Principles and practice of oral radiologic interpretat,ion. Chicago, Year Book Medical Publishers, 1963, p 161.
3. Stafne, E.C., and Slocumb, C.H. Idiopathic resorption of teeth. Am J Orthod & Oral Surg 30:41 Jan 1944. 4. Bell, T. The anatomy, physiology and diseases of teeth. Philadelphia, Carey & Lee Publishing, 1830, p 171. 5. Fothergill, J.A. Casual communications: pink spot. Trans Odontol Soc GB 32:213 May 7, 1900. 6. Mummery, J.H. The pathology of "pink spots" on teeth. Br Dent J 41:300, 1920. 7. Pritchard, G.B. A specimen showing "pink spot." R Soc Med Trans 24:1600, 1931. 8. Munch, J. Zur genese, klinik und therapie der sogenannten internen granulome. Dtsch Zahn Mund Kieferheilkd 4:424 June 1937. 9. Lepp, F.H. Progressive intradental resorption. Oral Surg 27:184 Feb 1968. 10. Massler, M., and Malone, A.J. Root resorption in human permanent teeth. A roentgenographic study. Am J Orthod 40:619 Aug 1954. 11. Phillips, J.R. Apical root resorption under orthodontic therapy. Angle Orthod 25:1 Jan 1955. 12. Kolas, S.; Cavalaris, C.J.; and Finch, R.R. Rad,iographic patterns of resorption seen in some gnathodental hard-tissue disturbances. Dent Clin North Am Nov 1968, p 589. 13. Auslander, W.P. Resorption internal and external. NY Dent J 31:397 Nov 1965.
D i f f e r e n t i a l d i a g n o s i s of i n t e r n a l a n d e x t e r n a l root r e s o r p t i o n Arnold H. G~t,,er, DDS; Thomas Mack, DDS: Richard Ca. Someflott, DDS: and Lawrence C. Walsh, DDS, Detroit
A n effort h a s b e e n m a d e to arrive at a p r e d i c t a b l e m e t h o d for correctly differentiatinq internal a n d external root resorption. The criteria for the differential diaqn o s i s a r e presented.
terizing internal resorption and suggested that certain cases require endodontic intervention and surgical repair. Lepp 9 distinguished between centrifugal, symmetric resorption beginning in the pulp chamber, and centripetal, asymmetric resorption beginning in the periodontium.
DIFFERENTIAL DIAGNOSIS Internal and external resorption have been identified as discrete entitiesA ,2 Radiographic interpretation of these lesions is of paramount importance in determining a modality of treatment and in establishing a prognosis. However, there appears to be no routine method of differentiating these two resorptive processes radiographically, z The purpose of this paper is to establish guidelines leading to a systematic approach for the differential diagnosis of internal and external root resorption. Bell 4 first reported on internal resorption in 1830. FothergilP referred to the condition as "pink spot." In 1920, Mummery 6 published the first extensive study of pink spots, and Pritchard 7 later showed histologically that internal resorption is comparable to a granuloma of the pulp. Munch, s in 1937, was the first to point out that internal resorption can often be delineated radiographically. He established the factors charac-
The basis of any attempt to establish a systematic approach toward a differential diagnosis rests on the ability to interpret normal tooth structures radiographically. Entities that must be considered are the normal tooth with its variations, dental caries, early pulpal death or incomplete root formation, internal resorption, and external resorption (see Table). To simplify the establishment of a differential diagnosis, the tooth is divided into three areas--apical, midroot, and coronal. Apical In the apical area, early pulpal death or incomplete root formation (Fig 1, top) and external resorption (Fig 1, bottom) may each show a blunted or shortened root with an open foramen. However, these conditions may be differentiated by the shape and size of the canal system and the appearance of the apex. With
early pulpal death or incomplete root formation, the canal system is large with parallel or divergent walls, and the apex may be blunderbuss in appearance. This contrasts with apical external resorption where the canal size will generally be smaller, and the walls will converge apically. The fact that orthodontic movement can cause external root resorption is well documented. 10,1t In most cases this resorption occurs at the apex and can be clearly seen radiographically (Fig 1, bottom).
Mid.root Internal and external resorption can occur on any surface of the tooth that contacts vital tissue. The margins of an internal resorptive lesion are sharp, smooth, and clearly defined (Fig 2) .2,12 Most internal resorptive lesions are symmetrical but may occur eccentrically, while external resorptions are not symmetrical and may occur on any external surface of the root. Within the margins of the lesion, internal resorption will show a defect that appears to be uniform in density. In contrast to this, external resorption, within its less well-defined margins, shows variations in density that may appear striated. This results from varying rates of resorption and repair, thus presenting a "moth-eaten" appearance. ~3
329
JOURNAL OF ENDODONTICS 1 VOL 2, NO 1I, NOVEMBER 1979
.
.
.
.
.
.
.
,
9
9
~2::: iiL,~n','~ ;:~:' i::" ~:~,,.;:~ i-~ :,~:.s,~.~:~'t(i-
::~:~ ~:;o~;;~ ;:~!'i,. . . . . . . .
. : 9 ~:
:?", ?A_I~x ~aortened, flattened, blunted, or square
:.:s
' : : ~: Marg~msof lesion are ragged and irregular i:~~ : m a y l ~ S U l ~ r ~ m p o s e d : o v e r canal
Because external resorption can occur on any lateral surface of the root, it may appear superimposed over the root canal system, presenting a difficult diagnostic problem. The shape of the root canal system can often lead to an accurate differential diagnosis. In external resorption, even though the lesion may be superimposed over the canal, the canal can be followed unaltered through the area of the defeet. In contrast to this, in internal resorption the unaltered canal or chamber cannot be followed through the lesion (Fig 3). The walls of the root canal system appear to balloon out, showing an enlarged area of uniform
330
9 Radiographic, appearance
density. There are no radiographic criteria to aid in ascertaining whether or not a perforation has occurred, regardless of the nature of the lesion. A n important radiographic aid that may be used to help distinguish these lesions can be referred to as the mesial-buccal-distal ( M B D ) rule. This rule is often applied during endodontic therapy to determine the relative position of roots. Two radiographs are exposed: one perpendicular to the tooth, the other from an angle mesial to the perpendicular in the same horizontal plane. Objects c l o s e r to the source of radiation will shift distally in relation to objects further from the source.
Fig 1--Radiographs show apical conditions." top, early pulpal death; bottom, external resorption.
JOURNAL OF ENDODONTICS
VOL 2, NO 11, NOVEMBER 1976
/
Fig 2--Radiographs show examples of internal and external resorption: top left, external resorption; top right, external resorption; bottom left, internal resorption; bottom right, internal resorption.
Fig 3----Diagrammatic representations of midroot resorptive lesions (Based on drawings by Leppg). Top, internal resorption: normal outline of canal cannot be followed through lesion; bottom, external resorption: normal outline of canal can be followed through lesion. 331
JOURNAL OF ENDODONTICS
In the context of this paper, the MBD rule may be applied in two ways. The first is to help in the differential diagnosis of internal resorption from external resorption. If the lesion is one of external resorption, it will shift from its superimposed position over the canal system on t h e mesially angulated radiograph (Fig 4, top left and right). Internal resorptive lesions, however, will not shift no matter how severe an angle the radiograph was taken from, although their shape may change (Fig 4, bottom left and right). Of course, circumstances may dictate a need to expose the angulated radiograph from the distal rather than from the mesial. This was the case in the two situations shown in Figure 4. The second use is to determine the relative position on the lateral root surface, should the lesion prove to be external resorption. If the lesion is located on or toward the palatal aspect, the mesially angulated radiograph will show it shifted to the mesial. This information is essential if surgery is indicated. A final consideration in the midroot area is the differential diagnosis between caries, external resorption, and internal resorption (Fig 5). This may become necessary because periodontally involved teeth often show midroot caries. Caries may easily be differentiated from internal resorption by the fact that, as in external resorption, the unaltered canal configuration can be followed through the area of the lesion. The outline of a carious lesion is more poorly defined than internal resorption. A difficult diagnostic problem is distinguishing midroot caries from external resorption radiographically. External resorption may show the classic striations within the margins of the lesion, whereas midroot caries usually does not. Therefore, a thorough clinical examination is always indicated.
332
VOL 2, NO 11, NOVEMBER 1979
Fig 4--Radiographs show use of MBD rule for differential diagnosis. Top left: external resorption, perpendicular; top right: external resorption, mesial; bottom le[t: internal resorption, perpendicular; bottom right: internal resorption, mesial.
JOURNAL OF ENDODONTICS
VOL 2, NO 11, NOVEMBER 1976
b: I Fig 5---Radiographs show three conditions that may be seen at level o/ alveolar crest: top left, external resorption; top right, dental caries; bottom left, internal resorption (lateral incisor).
Coronal
Internal resorption, external resorption, and caries can all occur in the coronal area of the tooth. Because vital tissue is necessary for either external or internal resorption to occur,
internal resorption can begin within the clinical crown whereas external resorption will not. However, external resorption m a y begin below the epithelial attachment, and once having penetrated the dentin, may extend incisally or occlusally to invade the clinical crown. In diagnosing these lesions in the coronal area, the same approach can be used as in the midroot section. Dental caries, as seen in Figure 5, top right, is usually located in the coronal aspect of the tooth. Caries can cause varying radiographic appearances, depending on location, and usually can be diagnosed by clinical examination. With internal resorption (Fig 2, bottom left) the canal or chamber
Fig 6--Radiographs show external resorption: top, apical; bottom, midroot.
shows an enlarged area that can vary considerably in size and location. The margins of the lesion may be sharp, smooth, and clearly defined. The lesion may be symmetrical or eccentric in nature. The normal canal outline cannot be followed through the lesion. External resorption can affect either the apex or the body of the root (Fig 6). If the resorption occurs at the 333
JOURNAL OF ENDODONTICS [ VOL 2, NO 11, NOVEMBER 1976
apex, the apex will appear shortened, blunted, or irregular in appearance. The foramen is visible in the apical region, and the opening of the canal can be seen. Assuming the tooth is mature, the walls of the root canal system converge apically. When external resorption occurs in the body of the root, the margins of the lesion are ragged and irregular. The lesion may be superimposed over the root canal, yet the normal unaltered canal outline can be followed through the region of the resorptive defect. 2 SUMMARY
AND CONCLUSIONS
Internal and external resorption can be differentially diagnosed by radiographs in most cases. In attempting to diagnose resorption, dental caries, external resorption, and internal resorption must be considered. The radiographic criteria for diagnosing these entities are presented along with the use of the MBD rule. Radiographs do not show whether or not the lesion has perforated the root. The methodology presented here provides the practitioner with a guide to identify predictably the particular
334
entity present, which enables him to establish a diagnosis and prognosis more readily, and to institute appropriate treatment. This paper is based on a table clinic that won the award of the best table clinic by graduate students at the annual scientific session of the American Association of Endodontists, New Orleans, 1975. The authors thank Mr. Eric Jacobs and Drs. Robert Hershey, Richard DeFillipo, Carl Botvinick, and Anthony Dietz for their help in completion of this paper. Drs. Gartner and Somerlott, formerly graduate students, are instructors in endodontics, and Drs. Mack and Walsh are former graduate students in endodontics, University of Detroit School of Dentistry. Requests for reprints should be directed to: Dr. Arnold H. Gar,tner, University of Detroit School of Dentistry, Department of Endodontics, 2985 E Jefferson Ave, Detroit, 48207. References
1. Rabinowitch, B.Z. Internal resorption. Oral Surg 33:263 Feb 1972. 2. Worth, H.M. Principles and practice of oral radiologic interpretat,ion. Chicago, Year Book Medical Publishers, 1963, p 161.
3. Stafne, E.C., and Slocumb, C.H. Idiopathic resorption of teeth. Am J Orthod & Oral Surg 30:41 Jan 1944. 4. Bell, T. The anatomy, physiology and diseases of teeth. Philadelphia, Carey & Lee Publishing, 1830, p 171. 5. Fothergill, J.A. Casual communications: pink spot. Trans Odontol Soc GB 32:213 May 7, 1900. 6. Mummery, J.H. The pathology of "pink spots" on teeth. Br Dent J 41:300, 1920. 7. Pritchard, G.B. A specimen showing "pink spot." R Soc Med Trans 24:1600, 1931. 8. Munch, J. Zur genese, klinik und therapie der sogenannten internen granulome. Dtsch Zahn Mund Kieferheilkd 4:424 June 1937. 9. Lepp, F.H. Progressive intradental resorption. Oral Surg 27:184 Feb 1968. 10. Massler, M., and Malone, A.J. Root resorption in human permanent teeth. A roentgenographic study. Am J Orthod 40:619 Aug 1954. 11. Phillips, J.R. Apical root resorption under orthodontic therapy. Angle Orthod 25:1 Jan 1955. 12. Kolas, S.; Cavalaris, C.J.; and Finch, R.R. Rad,iographic patterns of resorption seen in some gnathodental hard-tissue disturbances. Dent Clin North Am Nov 1968, p 589. 13. Auslander, W.P. Resorption internal and external. NY Dent J 31:397 Nov 1965.
