A Radiographic Study of Root Filled Teeth . . .
,.
,
C. E. Chapman. D.D.S., H.D.D., FDS. Conservation Department, Edinburgh Dental School.
The requirements which are fundamental for successful root canal therapy are asepsis and tlie preparation of a smooth, round tapering root cana!. The first is obtained by careful planning und discipline. The second necessitates an accurate assessment of the length of the tooth and meticulous mechanical instrumentation. It is only when these pre-requisites have been satisfied that the eanal can be obturated. In addition adequate drug therapy is required, although progress has been made in this direction beyond the dogmatic attitude of Appleton (1950) who stated that the problem of the pulpless tooth was essentially a bacteriologic one. The aim of the present investigation was to study the degree of success obtained in the complete obturation of the root eanal. The judgements of apparently clinically successful treatments were compared with the radiographic evidence. . , . ' Mechanical instrumentation is thought to he the most important stage in root canal therapy. Nicholls (1967) has demonstrated that 'sterilisation' of a canal can be achieved in approximately three-quarters of those treated, merely by mechanical instrumentation and irrigation alone. Ideal preparation of the canal involves an assurance that the canal is finally presented with a configuration that is circular in cross-section, tapering towards the apex and with a minute foramen (Chanoch, 1966). Precise cleansing and adequate mechanical instrumentation must be meticulous. In the treatment of tcetli with necrotic pulps it is necessary that all soft tissue and infected dentine within the canal should be removed. Care should be taken during this step to avoid infected material being forced through the apex. According to Baume et al (1974) total removal of vital tissue from the apical third of the tooth may not be necessary. He reports a 95% success rate for root treatments for vital teeth based on this principle. However, Ingle & Zcldow (1958), Seltzer ct al (1964) and Grossman (1943) all state that the most common cause of failure of root canal fillings is the result of incorrectly filled canals. They arc all o[ the opinion that anything siiort of total obliteration of the eentral space cannot be tolerated. Total obliteration of the central space of a tooth is usually carried out by means of silver or gutta percha points in conjunction with a sealing agent. Silver points, corresponding in diameter and taper to the prepared canal, were first introduced hy Jasper (1933). These are particularly suitable for canals which are narrow and markedly curved. However gutta percha points, whieh were first described by Bowman in 1867, are probably the most common root filling material in use today. With the introduction of 'matched points' in 1955, the dental profession can now be assured of a more effective and precise technique for the obliteration of the central space. A comparison of the diameters of standardised gutta percha points and root canal reamers* measured at 3mm and 6mm from the tip are set out in Figures 1 and 2. The graphs indicate that there is close correlation between ihc percha points and the reamers at the two selected regions and therefore such points arc very suitable for obliteration ot" the canal. However even when using the most precise and meticulous technique, there would appear to he occasions when complete obliteration of the root canal presents difficulties. It was hoped that this study would lead to an assessment of:— (1) the radiographic picture of the periapical area and (2) the degree of obliteration of the central space.
:
* Manufacturer Produit Dentaire 94
Journal of the British Endodontic Society, 1975 Vol.8 No.2
Tliis information was soughL because a survey of the success rate for root fillings was found to be impossible because of local factors. It has been stated by Ingle (1965) tiiat 6 and 12 month recalls for completed root fillings are valueless from an analytical point of view and that a small recall attendance for a two year recall might similarly invalidate the results obtained. For this reason the success rate for completed root fillings was abandoned. Only those patients for whom pre- and post-treatment radiographs were available were selected for this study. From these radiographs it was hujjcd that information would he provided on 1) the degree of obliteration of the central space, 2) the degree of scaling of the apical third of the canal and 3) ihe point of termination of the root filling. '- . ' , ' The degree of obliteration of the central space of a tooth is one aspect of root canal therapy which appears from ihe literature to have somewhat varying interpretations, lnglc (1965), Kulller (1958), Sommcr, et al (1966), Sellzer ct ar(1964), Grossman (1943) and Haga (1967), all stale thai the entire central space must be completely filled throughout its cnlirc volume as well as ils enlirc length. Total obliteration of the central space in the majority of maxillary anterior teeth, using the single point technique, is however impossible in view of tlic ovoid nature of the canal in the middle and coronal third of these teeth. The multiple point or the lateral condensation technique has to be used to ensure complete ohturalion of the canal. On the other hand, Marshall &: Masslcr (1961), Dow & Ingle (1955), Cr^iwford ik Larson (1958) and Going ct ;U (1960), all appear to place more emphasis on the adequacy of the seal in the apical region of the root canal. They do not necessarily insist on total obliteration of the central space, a situation which exists when a sectional root filling technique is used. The distance from the end of the root filling point to the apex of tiie tooth is a most important consideration in obliteration of the apical portion of the eanal. There is agrcemenl among Crane (1926), Hartzell (1930), Ingle (1965), Sominer, et ul (1966), that the apical constriction of a root eanal allows a seal to be established at this point more easily by virtue of the circular configuration of the canal. Isotope studies have demonstrated that when this region is prepared and scaled correctly, there is no evidence that fluid can percolate from the canal into the periapical tissues. The importance of this was considered such that it was taken as one of the aspects in this study. Care in the proper use of delicate endodontic instruments must always be borne in mind. Inept instrumentation within the root eanal may be responsible lor fractured instruments, perforation of the apex and for the unnecessary extrusion of material from the canal into the periapical tissues. Expulsion of material from the root canal during instrumentation has been demonstrated by Black (1917), Grossman (1950), Kurer (1966) and Cluipmim (1971). Material introduced into the periapical tissues in this way has been shown to cause irritation. However Matusow (1967) has suggested that the introduction of material into the periapical tissues may elicit a stimulative reaction. Similarly overfilling the canal causes irritation to the periapical tissues. This aspect of root canal therapy was considered by Ingle, (1965) and Sommcr, et al (1966) to mitigate against successful root canal therapy. METHOD A total of 792 patients, made up of 385 males and 407 females, for whom prc- and post-treatment radiographs were available and easily interpreted were selected lor tliis study. Complete records were not available for all patients, therefore a division into age groups was thought to be inappropriate. Tlie patients who had had root fillings completed in the Edinburgh Dental Hospital were selected from a period of tiiree years. All data obtained was recorded on puncli cards. The various teeth involved in this study are shown in the histogram in Fig.3. For case of assessment, only single Journal of the British Endodontic Society, 1975 Vol,8 No,2
95
- i
.•
1.25
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0.75
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Fig 1
5 25
4 JO
6
5 to
7 60
8 70
9 80
10 11 90 100
1 2 - reamers 110 - points
A comparison of the mean diameter of root canal reamers and standardised gutta percha points at 3mm from tip.
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.
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96
2 20
5 25
50
6 50
7 60
B 70
9 SO
10 90
11 100
12 110
- roaomrB - polntB
A comparison of the meaJi diameter of root canal reamers and standardised gutta percha points 6mm from the tip. Journal of the British Endodontic Society, 1975 Vol.8 No.2
rooted teeth were selected for this investigation. Sixty-three of the patients included in this study had had two root treatments completed at the same time or within a reasonably short space of time. Thirteen of these patients had had three root treatments completed. For record purposes each root treatment was investigated individually so that the number of patients and root treatments are the same. It is interesting to note largest variation in teeth treated was for maxillary lateral incisors (129 males and 158 females). Radiographs of the root filled teeth were obtained by use of the short cone and bisected angle technique. Because of the grain size of the X-Ray film used, it was found that a magnification of more than X 3V2 was unsatisfactory. All assessments were therefore made using a watchmakers lens of this magnification.
Oanlx^lM
Fig 3
Distribution of teeth treated in the survey.
RESULTS The radiographic appearance of the periapical region of the teeth before treatment was classified as follows, (1) Normal or thickened periodontal space. (2) Rarefaction around the apex, (a) small — less than 4mm in diamter, (b) medium — between 4mm and 8mm in diamter, (c) large — greater than 8mm in diamter. "Normal and thickened periodontal" spaces were classified under one heading as it is difficult to interpret with accuracy from a radiograph, if the periodontal space around a single tooth is pathologically thickened. Journal of the British Endodontic Society, 1975 Vol.8 No.2
97
The state of the periapex, obtained from an assessment of the radiographs in this study, is set out in Fig.4. Almost threequartcrs (74%) of the root treatments were carried out on teeth with areas of rarefaction. By far the largest number of these teeth had rarefaction which was greater than 8mm in diameter. A comparison between vital and pulpless root treatments is seen in Fig.5.
Normal and Rarefaction Rarefaction Rarefaction
State of periapex thickened periodontal space (small) (medium) (large)
Fig 4
Total 207 125 84 376
Percentage 26 16
11 47
Table to show radiographic assessment of the state of the periapex.
100
Vital 90
bo « 70 •f Co
o 30
30
kaxLllarj cntzuls
Fig 5
latcruls
otuiiaaa
rtwtcd
Distribution of vital and pulpless teeth treated in the survey. Journal of the British Endodontic Society, 1975 Vol.8 No.2
Any space that exists I)ctween the gutta pcrcba or silver point and the canal wall is usually due to the introduction of uir bubbles with tlie scaling agent at the time of completion of the treatment (Kig.G). In this investigation 158 of those teeth treated showed evidence of deficiencies in the sealing agent (Fig.7). However these voids were not always in a position which would necessarily lead to failure of the root treatment.
Fig 6 Radiograph illustrating the presence of voids as a result of the incorporation of air bubbles with the sealing agent.
Teeth investigated 324 287 61 52 68
Maxillary centrals Maxillary laterals Maxillary canines Mandibular incisors Single rooted posteriors Fig 7
No evidence of Air Voids 240 227
•
Evidence of Air V^oids
84 60
8
L
53 48 •
4
'
iS6
2
Table to show the distribution of canals exhibiting evidence of voids within the root filling.
Journal of the British Endodontic Society. 1975 Vol.8 No.2
99
The assumption was m^idc that :m assessment of the radiographs, using the criteria described, was sufficiently accurate for the purpose of this study. When examining any radiograph it should i)c remembered that it is a two dimensional rcpresenlation of a three dimensional situation. When assessing the quality of the apical seal therefore, some doubt on the adequacy of the effectiveness of the seal must exist. However, because the apical constriction of the root canal is usually circular in cross-section, (Sommcr, et al (1966), Ingle (1965), Kuttlcr (1958), Green (1955) and Chapman (1969)) it can be assumed thai if a circular point has reached such a position, a satisfactory seal has been achieved. The success of a root filling is considered to be more likely when the filling material reaches the apical constriction. If the filling finishes more than 2mm short of the apical third of the canal, there is a possibility that there will be eontinued irritation of the apical tissues and eventual failure of the root treatment. Figure 8 shows the distribution of the various distances that root fillings terminated in relationship to the radiographic apex of the teeth examined. Of the 792 teelh examined 695 had root fillings which finished within the acceptaljle limit of 0 to 2mm from the apex, and only 1% were more than the unacceptable distance of 2mm from the apex. The histogram (Fig.9) shows a record of those root fillings which extended beyond the apical foramen (11% of the total). However of the 695 teeth with correctly placed root fillings, 45 were considered to exhibit inadequate sealing of the apex (Fig.10).
162
UaxlXlary Uaxillarj-
latezuls
Usjtlllury
citiiJieo
iainglc
rooted
poaterioru
so
10
0.6
Fig 8 100
-
1 .0
-
2.Cnm
Gronter than 2»CEBn
Showing the distribution of variation of the distances the root fillings terminated from the apex. Journal of the British Endodontic Society, 1975 Vol.8 No.2
If the sole aim of cndodontie therapy were to cleanse and obturate the root canal completely to within 2mm of the apex, then all those teeth where there was evidence of underfilling or overfilling might be classified as failures. Figure 11 shows that there were 97 teeth (12%) in tliis study which were within this category; Figure 11 also shows that failure vvas reasonably uniformly distributed among the types of teeth treated.
20
10
0
Fig 9
greater
-
than
0,5aQ
Showing the distribution of the variation of the distances of those fillings which extended beyond the apex.
Distance from apex in mm 0-0.5 Maxillary centrals Maxillary laterals Maxillary canines Mandibular incisors Single rooted posteriors Fig 10
(25) (16) (2) (0)
18 10 2 0
(2)
1
0.6-1.0 6
1.1-2.0 1
3 0 0
3 0 0 0
1
Table to show the distribution of those teeth for which there appeared to be an inadequate seal at the apex.
Journal of the British Endodontic Society, 1975 Vol.S No.2
101
DISCUSSION For root canal therapy to be a success if is clearly desirable that preparation of the canal should be meticulously carried out. This must depend primarily on an accurate assessment of the length of the tooth. As there appears to be a close correlation in size between standardised gutta percha points :ind root canal reamers the use of these points is recommended. Care is necessary in limit preparalion of tbe canal to tbe apical constriction. Although Harty et al (1970) suggested that where periapical disturbance bad taken place the success rate was greater tban where no such interference bad occurred, this observation is regarded as speculative. The introduction of a root canal sealing agent by tbe use of a lentulo spiral is a simple procedure, bowever it carries witb it the risk that air bubbles may be introduced into the canal. The inclusion of air in this manner can clearly result in (ieficient obturation of tbe canal. The frequency with which voids were detected within tbe root canals of treated teetb suggests tbat the introduction of the sealing agent without air bubbles is dilTicult. If tbe success of root fillings depends on the accurate placement of tbe root filling point and the obliteratitin of tbe central .space, then this study shows a high rate of success. Of those points placed incorrectly however, tbe majority were shown to be through tbe apex. Tbis must have been due eitber to an incorrect assessment of tooth lengtb, loo forceful an insertion of tbe point, or to a discrepancy in tbe matching of tbe point compared witb the instrument used in the final preparation of the canal. It is considered that over-fillini^ the canal is more likely lo lead lo failure of ibe rool filling and tbis is borne out by tbe findings of Harty et al. Tbey found that overfilled canals failed twice as often as under-filled canals. CONCLUSIONS Of tbe root treatments examined 74% were performed on teeth with radiographic evidence of periapical rarefaction, the distribution for tbe various types oi leeth being remarkably uniform. 2. Tbe number of teetb witb root fillings placed within the acceptable range of 0 to 2mm from the apex was found to be 88% of tbe total. 3. Of the 695 with root fillings wbich were correctly placed, 6% showed some evidence of a poor apical seal. 4. In all, 1% of tbe teetb examined had rool fillings wbicb terminated at a poinl more tban 2mm sbort of Lbe radiograpbic apex. 5. Overfilled canals represented 11% of the total. 6. The addition of under-filled and over-filled canals represented 97 of tbe teelb examined, resulting in 12% of lbe root fillings in this study as being inadequate. 1.
ACKNOWLEDGEMENTS My grateful thanks are accorded to Dr. Waterslon and otber colleagues for their advice and helpful criticism during the preparation of tbis article. To Mr. I. Goddard and to Mr. R. Renton many tbanks for tbe photographic illustrations. References APPLETON, J. T. L. (1950) Baclerial Infection. 4th Ed. Lea Sc Fcbiger. Philadelphia. BAUME, L. J., RISK, L. B., & ROSSIKR, V. (1974) Radiographic control of radicular pulpotomy in category III pulps. / . Br. Endod. Soc. 7: 17—27. BLACK, G. V. (1917) A Work on Operative Dentistry. 3rd Ed. H. Kimpton. London. BOWMAN, G. A. (1867) History of Dentistry in Missouri, Ovid Bell Press, Fulton. 102
Journal of the British Endodontic Society, 1975 VoL8 No.2
CHANOCH, J. G. (1966) Root Canal Therapy./. Dent. Assoc. S. Afr. 21: 382-385 CHAPMAN, C. K. (19G9) A microscopic study of tbe apical region of human anterior teetb. y. Br. Endod. Soc. 3: 5 2 - 5 8 . CHAPMAN, C. E. (1971) The correlation between apical infection and instrumentation in endodontics./ Br. Endod. Soc. 5: 76—80. CRANE, A. B. (1926) Filling the Root Canal. Dc7il. Cosmos LXVIII: 709-713. CRAWFORD, \V. H. & LARSON, J. H. (1956) Fluid Penetration between fillings and teeth using Ca"'. /. Dent. Res. 35: 518-522. DOW, P. R. & INGLE, J. I. (1955) Morphology of tbe pulp cavity of tbe permanent teeth. Ora/5i(r^. 8: 1100-1104. GOING, R. E., MASSLER, M. & DUTE, H. L. (1960) Marginal penetrations of dental restorations as studied by crystal violet dye and I' 3 ' . /. Atn. Dent. Assoc. 61: 285-300. GREEN, D. (1955) Morphology of the pulp cavity of the permanent teeth. Oral Sure. 8: 743-759. GROSSMAN, L. I. (1943) Irrigation of root ciimih. J.Ain.Dent. Assoc. 30: I 9 1 5 - I 9 I 7 GROSSMAN, L. 1. (1950) Root Canal Therapy. 3rd Ed. H. Kimpton. London. HAGA, C. S. (1967) Microscopic measurements of root canal preparations following instrumentation. Northwestern University Bulletin. Fall: 11 — 19. HARTY, F. J., PARKINS, B. J. & WENGRAF, A. M. (1970) Success rate in root canal therapy: a restrospective study of conventional cases. Br. Dent. J. 128: 65-70. HARTZELL, T. B. (1930) Tbe pulpless tootb. Dent. Cosmos. LXXII: 1177. INGLE, J. 1. &: ZELDOW, B. J. (1958) An evaluation of mechanical instrumentation and ihe negative culture in endodontic therapy./. Am. Dent. Assoc. 57: 471—476. INGLE, J. 1. (1965) Endodontics. H. Kimpton. London. JASPER, E. A. (1933) Root Canal tberapy in modern dentistry. Dent. Cosmos. LXXV: 823-829. KURER, J. (1966) Immediate root canal sterilization. Dent. Pract. Dent. Ree. 16: 404-407. KUTTLER, Y. (1958) A precision and biologic root canal filling tecbnic. /. Am. Dent, Assoc. 56: 38-50. MARSHALL, F. J. & MASSLER, M. (1961) Sealing of pulpless teetb evaluated with radioisotopes./. Dent. Med. 16: 172-184. MAIUSOW, R. J. (1967) Microbiology of the pulp and periapical tissues: culture control. Deyit. Clin. North Atn. November 549. NICHOLLS, E. (1967) Endodontics, John Wright & Sons Ltd. Bristol. SELTZER, S., TURKENHOFF, S., VITO, A., GREEN, D. &: BENDER, I. B., (1964). A bistologic evaluation of periapical repair following positive and negative root canal cultures. Oral Surg. 17: 507-532. SOMMER, R. F., OSTRANDER, F. D. &: CROWLEY, Mary C. (1966) Clinical Endodontics. 3rd Ed. W. B. Saunders Co. Philadelphia & London.
Journal of the British Endodontic Society, 1975 Vol.S No.2
103
,.
,
C. E. Chapman. D.D.S., H.D.D., FDS. Conservation Department, Edinburgh Dental School.
The requirements which are fundamental for successful root canal therapy are asepsis and tlie preparation of a smooth, round tapering root cana!. The first is obtained by careful planning und discipline. The second necessitates an accurate assessment of the length of the tooth and meticulous mechanical instrumentation. It is only when these pre-requisites have been satisfied that the eanal can be obturated. In addition adequate drug therapy is required, although progress has been made in this direction beyond the dogmatic attitude of Appleton (1950) who stated that the problem of the pulpless tooth was essentially a bacteriologic one. The aim of the present investigation was to study the degree of success obtained in the complete obturation of the root eanal. The judgements of apparently clinically successful treatments were compared with the radiographic evidence. . , . ' Mechanical instrumentation is thought to he the most important stage in root canal therapy. Nicholls (1967) has demonstrated that 'sterilisation' of a canal can be achieved in approximately three-quarters of those treated, merely by mechanical instrumentation and irrigation alone. Ideal preparation of the canal involves an assurance that the canal is finally presented with a configuration that is circular in cross-section, tapering towards the apex and with a minute foramen (Chanoch, 1966). Precise cleansing and adequate mechanical instrumentation must be meticulous. In the treatment of tcetli with necrotic pulps it is necessary that all soft tissue and infected dentine within the canal should be removed. Care should be taken during this step to avoid infected material being forced through the apex. According to Baume et al (1974) total removal of vital tissue from the apical third of the tooth may not be necessary. He reports a 95% success rate for root treatments for vital teeth based on this principle. However, Ingle & Zcldow (1958), Seltzer ct al (1964) and Grossman (1943) all state that the most common cause of failure of root canal fillings is the result of incorrectly filled canals. They arc all o[ the opinion that anything siiort of total obliteration of the eentral space cannot be tolerated. Total obliteration of the central space of a tooth is usually carried out by means of silver or gutta percha points in conjunction with a sealing agent. Silver points, corresponding in diameter and taper to the prepared canal, were first introduced hy Jasper (1933). These are particularly suitable for canals which are narrow and markedly curved. However gutta percha points, whieh were first described by Bowman in 1867, are probably the most common root filling material in use today. With the introduction of 'matched points' in 1955, the dental profession can now be assured of a more effective and precise technique for the obliteration of the central space. A comparison of the diameters of standardised gutta percha points and root canal reamers* measured at 3mm and 6mm from the tip are set out in Figures 1 and 2. The graphs indicate that there is close correlation between ihc percha points and the reamers at the two selected regions and therefore such points arc very suitable for obliteration ot" the canal. However even when using the most precise and meticulous technique, there would appear to he occasions when complete obliteration of the root canal presents difficulties. It was hoped that this study would lead to an assessment of:— (1) the radiographic picture of the periapical area and (2) the degree of obliteration of the central space.
:
* Manufacturer Produit Dentaire 94
Journal of the British Endodontic Society, 1975 Vol.8 No.2
Tliis information was soughL because a survey of the success rate for root fillings was found to be impossible because of local factors. It has been stated by Ingle (1965) tiiat 6 and 12 month recalls for completed root fillings are valueless from an analytical point of view and that a small recall attendance for a two year recall might similarly invalidate the results obtained. For this reason the success rate for completed root fillings was abandoned. Only those patients for whom pre- and post-treatment radiographs were available were selected for this study. From these radiographs it was hujjcd that information would he provided on 1) the degree of obliteration of the central space, 2) the degree of scaling of the apical third of the canal and 3) ihe point of termination of the root filling. '- . ' , ' The degree of obliteration of the central space of a tooth is one aspect of root canal therapy which appears from ihe literature to have somewhat varying interpretations, lnglc (1965), Kulller (1958), Sommcr, et al (1966), Sellzer ct ar(1964), Grossman (1943) and Haga (1967), all stale thai the entire central space must be completely filled throughout its cnlirc volume as well as ils enlirc length. Total obliteration of the central space in the majority of maxillary anterior teeth, using the single point technique, is however impossible in view of tlic ovoid nature of the canal in the middle and coronal third of these teeth. The multiple point or the lateral condensation technique has to be used to ensure complete ohturalion of the canal. On the other hand, Marshall &: Masslcr (1961), Dow & Ingle (1955), Cr^iwford ik Larson (1958) and Going ct ;U (1960), all appear to place more emphasis on the adequacy of the seal in the apical region of the root canal. They do not necessarily insist on total obliteration of the central space, a situation which exists when a sectional root filling technique is used. The distance from the end of the root filling point to the apex of tiie tooth is a most important consideration in obliteration of the apical portion of the eanal. There is agrcemenl among Crane (1926), Hartzell (1930), Ingle (1965), Sominer, et ul (1966), that the apical constriction of a root eanal allows a seal to be established at this point more easily by virtue of the circular configuration of the canal. Isotope studies have demonstrated that when this region is prepared and scaled correctly, there is no evidence that fluid can percolate from the canal into the periapical tissues. The importance of this was considered such that it was taken as one of the aspects in this study. Care in the proper use of delicate endodontic instruments must always be borne in mind. Inept instrumentation within the root eanal may be responsible lor fractured instruments, perforation of the apex and for the unnecessary extrusion of material from the canal into the periapical tissues. Expulsion of material from the root canal during instrumentation has been demonstrated by Black (1917), Grossman (1950), Kurer (1966) and Cluipmim (1971). Material introduced into the periapical tissues in this way has been shown to cause irritation. However Matusow (1967) has suggested that the introduction of material into the periapical tissues may elicit a stimulative reaction. Similarly overfilling the canal causes irritation to the periapical tissues. This aspect of root canal therapy was considered by Ingle, (1965) and Sommcr, et al (1966) to mitigate against successful root canal therapy. METHOD A total of 792 patients, made up of 385 males and 407 females, for whom prc- and post-treatment radiographs were available and easily interpreted were selected lor tliis study. Complete records were not available for all patients, therefore a division into age groups was thought to be inappropriate. Tlie patients who had had root fillings completed in the Edinburgh Dental Hospital were selected from a period of tiiree years. All data obtained was recorded on puncli cards. The various teeth involved in this study are shown in the histogram in Fig.3. For case of assessment, only single Journal of the British Endodontic Society, 1975 Vol,8 No,2
95
- i
.•
1.25
•
•.
' I
1.00
0.75
0.50
....^r
-^
reamorfl
0.25
0
1 2 15 20
Fig 1
5 25
4 JO
6
5 to
7 60
8 70
9 80
10 11 90 100
1 2 - reamers 110 - points
A comparison of the mean diameter of root canal reamers and standardised gutta percha points at 3mm from tip.
1.25
1.00 '
.
.
.
/
.
•
.
•
•
•
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.
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.
.
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0.25
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• •
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,
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0
15
Fig 2
96
2 20
5 25
50
6 50
7 60
B 70
9 SO
10 90
11 100
12 110
- roaomrB - polntB
A comparison of the meaJi diameter of root canal reamers and standardised gutta percha points 6mm from the tip. Journal of the British Endodontic Society, 1975 Vol.8 No.2
rooted teeth were selected for this investigation. Sixty-three of the patients included in this study had had two root treatments completed at the same time or within a reasonably short space of time. Thirteen of these patients had had three root treatments completed. For record purposes each root treatment was investigated individually so that the number of patients and root treatments are the same. It is interesting to note largest variation in teeth treated was for maxillary lateral incisors (129 males and 158 females). Radiographs of the root filled teeth were obtained by use of the short cone and bisected angle technique. Because of the grain size of the X-Ray film used, it was found that a magnification of more than X 3V2 was unsatisfactory. All assessments were therefore made using a watchmakers lens of this magnification.
Oanlx^lM
Fig 3
Distribution of teeth treated in the survey.
RESULTS The radiographic appearance of the periapical region of the teeth before treatment was classified as follows, (1) Normal or thickened periodontal space. (2) Rarefaction around the apex, (a) small — less than 4mm in diamter, (b) medium — between 4mm and 8mm in diamter, (c) large — greater than 8mm in diamter. "Normal and thickened periodontal" spaces were classified under one heading as it is difficult to interpret with accuracy from a radiograph, if the periodontal space around a single tooth is pathologically thickened. Journal of the British Endodontic Society, 1975 Vol.8 No.2
97
The state of the periapex, obtained from an assessment of the radiographs in this study, is set out in Fig.4. Almost threequartcrs (74%) of the root treatments were carried out on teeth with areas of rarefaction. By far the largest number of these teeth had rarefaction which was greater than 8mm in diameter. A comparison between vital and pulpless root treatments is seen in Fig.5.
Normal and Rarefaction Rarefaction Rarefaction
State of periapex thickened periodontal space (small) (medium) (large)
Fig 4
Total 207 125 84 376
Percentage 26 16
11 47
Table to show radiographic assessment of the state of the periapex.
100
Vital 90
bo « 70 •f Co
o 30
30
kaxLllarj cntzuls
Fig 5
latcruls
otuiiaaa
rtwtcd
Distribution of vital and pulpless teeth treated in the survey. Journal of the British Endodontic Society, 1975 Vol.8 No.2
Any space that exists I)ctween the gutta pcrcba or silver point and the canal wall is usually due to the introduction of uir bubbles with tlie scaling agent at the time of completion of the treatment (Kig.G). In this investigation 158 of those teeth treated showed evidence of deficiencies in the sealing agent (Fig.7). However these voids were not always in a position which would necessarily lead to failure of the root treatment.
Fig 6 Radiograph illustrating the presence of voids as a result of the incorporation of air bubbles with the sealing agent.
Teeth investigated 324 287 61 52 68
Maxillary centrals Maxillary laterals Maxillary canines Mandibular incisors Single rooted posteriors Fig 7
No evidence of Air Voids 240 227
•
Evidence of Air V^oids
84 60
8
L
53 48 •
4
'
iS6
2
Table to show the distribution of canals exhibiting evidence of voids within the root filling.
Journal of the British Endodontic Society. 1975 Vol.8 No.2
99
The assumption was m^idc that :m assessment of the radiographs, using the criteria described, was sufficiently accurate for the purpose of this study. When examining any radiograph it should i)c remembered that it is a two dimensional rcpresenlation of a three dimensional situation. When assessing the quality of the apical seal therefore, some doubt on the adequacy of the effectiveness of the seal must exist. However, because the apical constriction of the root canal is usually circular in cross-section, (Sommcr, et al (1966), Ingle (1965), Kuttlcr (1958), Green (1955) and Chapman (1969)) it can be assumed thai if a circular point has reached such a position, a satisfactory seal has been achieved. The success of a root filling is considered to be more likely when the filling material reaches the apical constriction. If the filling finishes more than 2mm short of the apical third of the canal, there is a possibility that there will be eontinued irritation of the apical tissues and eventual failure of the root treatment. Figure 8 shows the distribution of the various distances that root fillings terminated in relationship to the radiographic apex of the teeth examined. Of the 792 teelh examined 695 had root fillings which finished within the acceptaljle limit of 0 to 2mm from the apex, and only 1% were more than the unacceptable distance of 2mm from the apex. The histogram (Fig.9) shows a record of those root fillings which extended beyond the apical foramen (11% of the total). However of the 695 teeth with correctly placed root fillings, 45 were considered to exhibit inadequate sealing of the apex (Fig.10).
162
UaxlXlary Uaxillarj-
latezuls
Usjtlllury
citiiJieo
iainglc
rooted
poaterioru
so
10
0.6
Fig 8 100
-
1 .0
-
2.Cnm
Gronter than 2»CEBn
Showing the distribution of variation of the distances the root fillings terminated from the apex. Journal of the British Endodontic Society, 1975 Vol.8 No.2
If the sole aim of cndodontie therapy were to cleanse and obturate the root canal completely to within 2mm of the apex, then all those teeth where there was evidence of underfilling or overfilling might be classified as failures. Figure 11 shows that there were 97 teeth (12%) in tliis study which were within this category; Figure 11 also shows that failure vvas reasonably uniformly distributed among the types of teeth treated.
20
10
0
Fig 9
greater
-
than
0,5aQ
Showing the distribution of the variation of the distances of those fillings which extended beyond the apex.
Distance from apex in mm 0-0.5 Maxillary centrals Maxillary laterals Maxillary canines Mandibular incisors Single rooted posteriors Fig 10
(25) (16) (2) (0)
18 10 2 0
(2)
1
0.6-1.0 6
1.1-2.0 1
3 0 0
3 0 0 0
1
Table to show the distribution of those teeth for which there appeared to be an inadequate seal at the apex.
Journal of the British Endodontic Society, 1975 Vol.S No.2
101
DISCUSSION For root canal therapy to be a success if is clearly desirable that preparation of the canal should be meticulously carried out. This must depend primarily on an accurate assessment of the length of the tooth. As there appears to be a close correlation in size between standardised gutta percha points :ind root canal reamers the use of these points is recommended. Care is necessary in limit preparalion of tbe canal to tbe apical constriction. Although Harty et al (1970) suggested that where periapical disturbance bad taken place the success rate was greater tban where no such interference bad occurred, this observation is regarded as speculative. The introduction of a root canal sealing agent by tbe use of a lentulo spiral is a simple procedure, bowever it carries witb it the risk that air bubbles may be introduced into the canal. The inclusion of air in this manner can clearly result in (ieficient obturation of tbe canal. The frequency with which voids were detected within tbe root canals of treated teetb suggests tbat the introduction of the sealing agent without air bubbles is dilTicult. If tbe success of root fillings depends on the accurate placement of tbe root filling point and the obliteratitin of tbe central .space, then this study shows a high rate of success. Of those points placed incorrectly however, tbe majority were shown to be through tbe apex. Tbis must have been due eitber to an incorrect assessment of tooth lengtb, loo forceful an insertion of tbe point, or to a discrepancy in tbe matching of tbe point compared witb the instrument used in the final preparation of the canal. It is considered that over-fillini^ the canal is more likely lo lead lo failure of ibe rool filling and tbis is borne out by tbe findings of Harty et al. Tbey found that overfilled canals failed twice as often as under-filled canals. CONCLUSIONS Of tbe root treatments examined 74% were performed on teeth with radiographic evidence of periapical rarefaction, the distribution for tbe various types oi leeth being remarkably uniform. 2. Tbe number of teetb witb root fillings placed within the acceptable range of 0 to 2mm from the apex was found to be 88% of tbe total. 3. Of the 695 with root fillings wbich were correctly placed, 6% showed some evidence of a poor apical seal. 4. In all, 1% of tbe teetb examined had rool fillings wbicb terminated at a poinl more tban 2mm sbort of Lbe radiograpbic apex. 5. Overfilled canals represented 11% of the total. 6. The addition of under-filled and over-filled canals represented 97 of tbe teelb examined, resulting in 12% of lbe root fillings in this study as being inadequate. 1.
ACKNOWLEDGEMENTS My grateful thanks are accorded to Dr. Waterslon and otber colleagues for their advice and helpful criticism during the preparation of tbis article. To Mr. I. Goddard and to Mr. R. Renton many tbanks for tbe photographic illustrations. References APPLETON, J. T. L. (1950) Baclerial Infection. 4th Ed. Lea Sc Fcbiger. Philadelphia. BAUME, L. J., RISK, L. B., & ROSSIKR, V. (1974) Radiographic control of radicular pulpotomy in category III pulps. / . Br. Endod. Soc. 7: 17—27. BLACK, G. V. (1917) A Work on Operative Dentistry. 3rd Ed. H. Kimpton. London. BOWMAN, G. A. (1867) History of Dentistry in Missouri, Ovid Bell Press, Fulton. 102
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CHANOCH, J. G. (1966) Root Canal Therapy./. Dent. Assoc. S. Afr. 21: 382-385 CHAPMAN, C. K. (19G9) A microscopic study of tbe apical region of human anterior teetb. y. Br. Endod. Soc. 3: 5 2 - 5 8 . CHAPMAN, C. E. (1971) The correlation between apical infection and instrumentation in endodontics./ Br. Endod. Soc. 5: 76—80. CRANE, A. B. (1926) Filling the Root Canal. Dc7il. Cosmos LXVIII: 709-713. CRAWFORD, \V. H. & LARSON, J. H. (1956) Fluid Penetration between fillings and teeth using Ca"'. /. Dent. Res. 35: 518-522. DOW, P. R. & INGLE, J. I. (1955) Morphology of tbe pulp cavity of tbe permanent teeth. Ora/5i(r^. 8: 1100-1104. GOING, R. E., MASSLER, M. & DUTE, H. L. (1960) Marginal penetrations of dental restorations as studied by crystal violet dye and I' 3 ' . /. Atn. Dent. Assoc. 61: 285-300. GREEN, D. (1955) Morphology of the pulp cavity of the permanent teeth. Oral Sure. 8: 743-759. GROSSMAN, L. I. (1943) Irrigation of root ciimih. J.Ain.Dent. Assoc. 30: I 9 1 5 - I 9 I 7 GROSSMAN, L. 1. (1950) Root Canal Therapy. 3rd Ed. H. Kimpton. London. HAGA, C. S. (1967) Microscopic measurements of root canal preparations following instrumentation. Northwestern University Bulletin. Fall: 11 — 19. HARTY, F. J., PARKINS, B. J. & WENGRAF, A. M. (1970) Success rate in root canal therapy: a restrospective study of conventional cases. Br. Dent. J. 128: 65-70. HARTZELL, T. B. (1930) Tbe pulpless tootb. Dent. Cosmos. LXXII: 1177. INGLE, J. 1. &: ZELDOW, B. J. (1958) An evaluation of mechanical instrumentation and ihe negative culture in endodontic therapy./. Am. Dent. Assoc. 57: 471—476. INGLE, J. 1. (1965) Endodontics. H. Kimpton. London. JASPER, E. A. (1933) Root Canal tberapy in modern dentistry. Dent. Cosmos. LXXV: 823-829. KURER, J. (1966) Immediate root canal sterilization. Dent. Pract. Dent. Ree. 16: 404-407. KUTTLER, Y. (1958) A precision and biologic root canal filling tecbnic. /. Am. Dent, Assoc. 56: 38-50. MARSHALL, F. J. & MASSLER, M. (1961) Sealing of pulpless teetb evaluated with radioisotopes./. Dent. Med. 16: 172-184. MAIUSOW, R. J. (1967) Microbiology of the pulp and periapical tissues: culture control. Deyit. Clin. North Atn. November 549. NICHOLLS, E. (1967) Endodontics, John Wright & Sons Ltd. Bristol. SELTZER, S., TURKENHOFF, S., VITO, A., GREEN, D. &: BENDER, I. B., (1964). A bistologic evaluation of periapical repair following positive and negative root canal cultures. Oral Surg. 17: 507-532. SOMMER, R. F., OSTRANDER, F. D. &: CROWLEY, Mary C. (1966) Clinical Endodontics. 3rd Ed. W. B. Saunders Co. Philadelphia & London.
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