- Email: [email protected]
Apical root anatomy of impacted maxillary canines
Apical root anatomy of impacted maxillary canines .
A clinical and radiographic
study
Madeleine Rohlin, D.D.S.. Odont.D.,* and Lars Rundquist, D.D.S.,** Malmii, Sweden SCHOOL
OF DENTISTRY,
UNIVERSITY
OF LUND
When planning autotransplantation of impacted maxillary canines, it is advantageous to know not only the position but also the root anatomy. Radiographic and clinical findings on the root anatomy of 65 impacted maxillary canines were compared. The apices were judged as straight or deflected. The positions of the canines were also recorded. Twenty-eight canines (43%) had a straight and 37 (57%) a deflected apex. The radiographic diagnosis was confirmed in 49 canines, which means a diagnostic accuracy of 75%. The misinterpretation, consisting of seven false-positive and nine false-negative diagnoses, was due to insufficient radiographic examination (7 canines), observation errors (7 canines), and limitations of radiographic examination (2 canines). No association was found between the root anatomy and position. The results show than an optimal radiographic examination and knowledge of any apical deflection are valuable aids to operative assessment of impacted maxillary canines. (ORAL SURG. 58:141-147, 1984)
D
uring the last two decades,several studies have discussedautotransplantation of impacted maxillary canines.‘-” The importance of avoiding surgical trauma to the periodontal membrane for a favorable prognosis was already emphasized in the comprehensive study on transplantation of impacted canines by Widmanlz and has later been confirmed by Andreasen.13It seemsalso to be of utmost importance that the extra-alveolar time for the transplant is as short as possible.*4-‘6This means that the transplant should be transferred to the new alveolus as soon as the preparation is completed. Optimal planning of the surgical procedure is therefore necessary. This is facilitated by accurate evaluation of the position and anatomy of the transplant.2*8’I7 The aim of this study was to compare radiographic and surgical findings on the root anatomy of impacted maxillary canines. In addition, the position of these canines was related to the root anatomy. PATIENTS AND METHODS Patients
Fifty-five consecutive patients referred for autogeneic transplantation (terminology according to Urist18) were collected retrospectively for this study. *Department of Oral Radiology. **Department of Oral Surgery and Oral Medicine.
There were 35 right and 30 left impacted maxillary canines. Table I presents the sex and age distribution of the patients. Clinical examination
Preoperatively, a canine was classified as nonerupted when the tooth had no connection with the oral cavity and as partially erupted when part of the tooth was seen or could be probed from the oral cavity. Radfographic
examination
The routine for examination of impacted maxillary canines consisted of two periapical radiographs and one maxillary axial view. The two periapical radiographs were taken as one orthoradial and one horizontally eccentric radiograph. The routine examination was supplemented with an occlusal view for 28 canines, a tangential view for 11 canines, and hypocycloidal tomography for 2 canines. For 15 canines a panoramic radiograph taken in connection with a complete-mouth examination was also available. The radiographic interpretation of the root anatomy was performed by one of the authors (M.R.). The apex was judged as being straight or deflected. The projection showing the clearest image of the apical region was noted and any signs of deflection were 141
142 Rohlin and Rundquist
Oral Surg. August. I984
Table
I. Sex and age distribution for 55 patients Age (years) Mean age
Sex
1.5-19
6 I
Female Male Total
20-24
(2)
25-29
6
i-
8 (1)
2
A--
8
13
30-34
8 (2) - 7 (1)
15
35-39
40-44
45-49
>49
(wars)
I
1 (1)
2 (1)
1
29
2 3
4 5
0 2
1. 2
33 30
Number of patients with bilateral transplantation of maxillary canines is shown in parentheses.
II. Position of impacted maxillary canines in relation to surgical findings of apical root anatomy (n = 65)
Table
Buccal/lingual
Eruption
position
Angular position
’ Lingual
Straight
apex
Dejected
Vertical Mesioangular I Horizontal
4 14 2
I 15 6
Vertical Mesioangular Vertical Mesioangular
2 4
3 5
I I
3
Vertical I Mesioangular
0 0
2
apex
Nonerupted , Within the dental arch
Partially
I
erupted
Lingual
Within the dental arch
tll. Comparison of surgical and radiographic findings on the apical root anatomy of impacted maxillary canines (n = 65)
Table
Radiographic SurgicalJindings
Straight
Straight apex Deflected apex Total
apex
findings Deflected apex
Total
21
I
28
-9
28
21
30
35
65
Diagnostic accuracy g = 75%.
recorded. The retention level of the crown, buccal/ lingual, and angular positions of the tooth were subgrouped according to the criteria presented by Nordenram.lp Thus, the retention level wasjudged as superficial (coronal to the cervical region of neighboring teeth), medium (between the cervical and apical regions of neighboring teeth) or deep (apical to the neighboring teeth). Also, the position of the crown was classified as buccal, within the dental arch, or lingual. The angular position was classified as vertical, mesioangular, distoangular, or horizontal. surgery
All transplantations were performed by one of the authors (L.R.) with the aid of local anesthesia (48 patients) or general anesthesia (7 patients). During
1
I
the extra-alveolar period the tooth was inspected and the apex was evaluated as straight or deflected. When a deflection was found, the approximate direction in situ was estimated. Comparison findings
between radktgraphic
and surgical
The radiographic and surgical findings were compared. When the radiographic interpretation differed from the surgical findings, the radiographs were studied once more in an attempt to explain the disparity. RESULTS Twenty-eight maxillary canines (43%) presented a straight apex and 37 canines (57%) a deflected apex. There were 15 right and 13 left canines with a straight apex and 20 right and 17 left canines with a deflected apex. Because of the necessity of rotating the canine during surgery, it was extremely difficult to judge the direction of the apical deflection in situ. However, our impression was that most of the deflected apices were mainly buccally deflected. The position of the maxillary canines in relation to the apical root anatomy is presented in Table II. There was no association between position and apical root anatomy of these impacted maxillary canines. Fiftysix canines were nonerupted, and nine were partially erupted. Only one canine was in a superficial posi-
Volume58 Number 2
Apical root anatomy of impacted maxillary canines 143
Fig. 1. Periapical radiographs of an impacted right maxillary canine with a deflected apex. The signs of apical deflection are more evident in A. The superior root surface is positioned close to the wall of the maxillary sinus.
Fig. 2. Periapical radiographs of an impacted left maxillary canine with a deflected apex. A, Note the cross-sectional view of the root canal (arrow). B, Bending of the apical part of the periodontal membrane is seen on the superior root surface.
tion, and the remaining 64 were in a medium position, that is, between the cervical and apical
regions of the lateral incisor. No canine was buccally positioned, 26% of the canines were observed within the dental arch, and 74% were lingually positioned. Most of the canines (68%) were located mesioangularly, and the remaining canines either vertically or horizontally. Table III compares the surgical and radiographic findings on the apical root anatomy. The radiograph-
ic diagnosis was confirmed for 49 canines, representing a diagnostic accuracy of 75%. For 28 canines the radiographic diagnosis was true-positive (deflected apex), and for 21 canines it was true-negative (straight apex). Of the cases with a true-positive diagnosis, 17 canines exhibited an obvious deflection radiographically (Fig. l), whereas only indirect signs of the apical deflection were observed for 11 canines. The indirect signs consisted of bowing of the periodontal membrane, with or without a cross-sectional
144 Rohiin and Rundquist
Oral Surg. August, 1984
Fig. 3. Impacted right maxillary canine. A, Periapical radiograph showing deviation of the periodontal membrane in the superior and apical parts of the root. The deviation was interpreted as a deflection. B, Photograph of the canine shown in A.
Fig. 4. Photograph of a canine showing slight bowing of the apical part of the root.
view of the root canal for six canines (Fig. 2). In another three canines only the periodontal membrane deviated (Fig. 3), and in two canines the apices were diffusely depicted even though the projection and blackening of the radiographs were optimal and revealed surrounding areas clearly. The deflection of the apex was observed in the periapical radiographs in 24 cases. For several canines, however, the deflection was clearly depicted in only one of the periapical radiographs (compare
Fig. 1, A with Fig. 1, B). In three casesthe deflection was seen only in the occlusal view. For one canine only, the tangential view revealed the deflection. For some canines, the panoramic radiographs depicted the deflection when it was shown distinctly in the periapical radiographs. The axial maxillary view did not depict the root anatomy; nor did the lateral tomograms. The disparities between surgical and radiographic findings for 16 canines are presented in Table IV. In four out of seven false-positive diagnoses, a deflection observed radiographically turned out to be a slight bow at inspection (Fig. 4). Among nine falsenegative diagnoses, the defkction was impossible to detect at review in sevencanines (Fig 5). The causes of errors were insufficient examination (seven canines), observation errors (seven canines), and limitations of radiographic examination (two canines). DISCUSSION
After the third molar, the maxillary canine is the tooth that is most frequently impacted, with a reported prevalence of 0.9% to 2%~~~~’Among impacted maxillary canines, 76% to 93% are positioned lingually or within the dental arch and the remainder are displaced buccally.25-30Bucoally displaced maxillary canines can be treated interceptively with a good prognosis, whereas lingually impacted maxillary canines have the least tendency to erupt.26 These facts explain why, in this study, impacted maxillary canines of persons with a mean age of 30
Apical root anatomy of impacted maxillary canines 145
Volume58 Number 2
Fig. 5. Impacted left maxillary canine. A and B, Periapical radiographs of an apex interpreted as straight. C, Photograph of the canine shown in A and B. The apical part of the root is deflected. This false-negative diagnosis was probably due to poor image quality with too low blackening and overaxial projection. Table IV. Disparity
between surgical and radiographic findings on the apex of impacted maxillary canines
(n = 65) No. of canines
SurgicaiJinding
Radiographic finding
Radiographic errors
False-positive False-positive
5
Straight apex
Deflectedapex
2
Straight apex
Deflected apex
5
Deflected apex
Straight apex
False-negative
2 2
Deflected apex Deflected apex
Straight apex Straight apex
False-negative False-negative
Errors
Error obviousat review;observationerror Overaxialx-ray films showingcut apex interpreted as deflection; insufficient examination X-ray films overaxial and too low blackening; insufficient examination Error obvious at review; observation error Impossible to detect deflection even with good
imagequality; limitation of radiographic examination
years and referred for autotransplantation were positioned lingually or within the dental arch. The mesioangular position was seen most frequently, in accordance with observations by Cranin and Cranin30and Lind.3’ According to Marsh,32displacement toward a horizontal position, observed in 32%, might be a result of continued growth of the root. The presence of a deflected apex of impacted canines has previously been only briefly mentioned.8*27’ 33A deflection also seemsto be present in an illustration published by Azaz and Shteyer.34The incidence of apex deflection was high in our study, which might be due to the selection procedure and the criteria used. No exact clinical demarcation between straight and deflected apices was possible since there were intermediate forms. Apices with a gentle bow were classified as straight. It is reason-
able to deduce that the presenceof a deflection of the apex is the result rather than a causeof impaction. In the region where the apical part of the impacted canine is developed, the cortical linings of the nasal cavity and the maxillary sinus, as well as the anterior border of the maxilla, limit a narrow space in the trabecular bone. Since developing roots are plastic and their form seems to be dependent upon the immediate environment,3sthe root apex of impacted maxillary canines might develop a deflection, as shown in Fig. 6. Similarly, for lower third molars the compact bone of the walls of the mandibular canal will not be deflected by developing roots, but the roots in the precalcification stage seek an easier growth course and are deflected by the cana1.36 Moreover, when immobilizing erupting molars of hamsters, Greggs5found that the proliferating apical
146
Rohlin and Rundquist
Oral Surg. August, 1984
6. Left maxillary canine. A, Periapical radiograph showing an apex that is not fully mineralized. B, Periapical radiograph 2 years later, revealing a deflection of the apex.
Fig.
dentin appeared to be bent or distorted when the root apex was stabilized. Even though the radiographic anatomy of the maxillary cuspid region is complicated, the present diagnostic accuracy of 75% should be further increased when the diagnostic criteria and major pitfalls for impacted maxillary canines are better known. Most diagnostic errors were due to insufficient radiographic examination or observation errors. Since the study was a retrospective one, the quality of the radiographs was in some casesinsufficient. The radiographs were taken mainly for diagnosis of the position, since the varying apical anatomy was not fully considered at the time of examination. The vertical angulation for the periapical radiographs should be underaxial rather than overaxial. The latter projection will show a shortened root and hide a buccal deflection of the apex. To depict the apex clearly, the image should preferably be projected into the maxillary sinus, avoiding the bony walls of the maxillary sinus and the nasal cavity. Optimal blackening of the radiographs is also of utmost importance. An optimal quality of the radiographs will also facilitate assessmentof root resorption of adjacent teeth, which is reported to occur in 7.5% of cases,37and resorption of the crown of the impacted canine, which occurs in 14%.34 This study indicates that in cases with a root deflection the occlusal as well as the tangential views might be valuable aids to diagnosis. The axial view was applicable only for diagnosing the position of the canine. As no association was found between the apical anatomy and any particular position, the
position could not be used as any indicator of the apical anatomy. The number of observation errors may decrease when more knowledge about the radiographic apical anatomy becomes available. Continuous communication between the radiologist and the surgeon is therefore important so that also indirect, minor radiographic signs of the anatomy are learned. The cross-sectional view of the apical part of the root canal and atypical outline of the periodontal membrane are such signs. Each radiographic examination of nonerupted canines so as to be able to start suitable treatment has been recommended, at the age of 8 to 9 years27. 31.38 or at 11 years.26Later, when the root is fully mineralized, not only a possible deflection of the apex but also diminished eruptive force have to be considered. When orthodontic treatment is not possible or is not accepted by the patient, autotransplantation might be the treatment of choice. In view of the importance of atraumatic removal of the autograft for a good prognosis, a correct radiographic examination would be a prerequisite for the achievement of an optimal clinical result. REFERENCES 1. Simpson W: The reimplanted maxillary canine. Br J Oral Surg 4:150-154, 1959. 2. Moss JP: Autogenous transplantation of maxillary canines. ORAL SURC 26~775-783,1968. 3. Hovinga J: Autotransplantation of maxillary canines: a longterm evaluation. ORAL SURG 27:701-708, 1969. 4. Thonner KE, Meijer M: Autotransplantation of impacted upper canines: a clinical and histologic investigation. Odontol T 77:113-119, 1969.
Volume 58 Number 2
Apical root anatomy of impacted maxillary canines 147
5. Thonner KE: Autogenous transplantation of unerupted maxillary canines: a clinical and histologic investigation over five years. Dent Pratt 21:251-257, 1971. 6. Cook RM: The current status of autogenous transplantation as applied to the maxillary canine. Int Dent J 22: 286-300, 1972. 7. Lovius BBJ, Atherton JD. Wynne THM, Finch LD: Br J Orthod 1: 27-33 1974. 8. Oksala E: Autotransplantation of vital maxillary canines: a clinical and radiographic study. Proc Finn Dent Sot 70: Suppl. 1, 1974. 9. McCay C: The unerupted maxillary canine: an assement of the role of surgery in 2,500 treated cases. Br Dent J 145: 207-210, 1978. 10. Kristerson L, Kvint S: Autotransplantation av tander-10 Brs erfarenheter. Tandlakartidningen 73: 598-606, 1981. 1 I. Hardy P: The autogenous transplantation of maxillary canines. Br Dent J 153: 183-186, 1982. 12. Widman L: Om transplantation av retinerade horntinder. Sven Tandlakartidn 8: 131-160, 1915. 13. Andreasen JO: Relationship between cell damages in the periodontal ligament after replantation and subsequentdevelopment of root resorption. Acta Odontol Stand 39: 15-25, 1981. 14. Andreasen JO, Hjglrting-Hansen E, Jdlst 0: A clinical and radiographic study of 76 autotransplanted third molars. Stand J Dent Res 78: 512-523, 1970. 15. Hansen J, Fibaeck B: Clinical experience of auto- and allotransplantation of teeth. Int Dent J 22: 270-285, 1972. 16. Andreasen JO: The effect of extra-alveolar period and storage media upon periodontal and pulpal healing after replantation of mature permanent incisors in monkeys. Int J Oral Surg 10: 43-53, 1981. 17. Andreasen JO, Hjdrting-Hansen E: Replantation and autotransplantation of teeth. Trans Congr Int Assoc Oral Surg, pp. 430-433, 1970. 18. Urist MR: Bone transplants and implants. In Fundamental and clinical bone physiology, Philadelphia, 1980,J. B. Lippincott Company, pp. 331-368. 19. Nordenram A: Retinerade tinder. In Hjdrting-Hansen L, Nordenram A, Aas E (editors): Oral kirurgi, ed 2, Copenhagen, 1978, Munksgaard, pp. 184-188. 20. Cramer HC: Dental survey of one thousand adult males: a statistical study correlated with physical and laboratory findings. J Am Dent Assoc 16: 122-128, 1929. 21. Rohrer A: Displaced and impacted canines. Int J Orthod 15: 1002-1020. 1929.
22. Mead SV: Incidence of impacted teeth. Int J Orthod 16: 885-890, 1930. 23. Baden E: Surgical management of unerupted canines and premolars. ORAL SURG 9: 141-192, 1956. 24. Dachi SF, Howell FV: A survey of 3,874 routine full-mouth radiographs. II. A study of impacted teeth. ORAL SURG 14: 1165-1169, 1961.
25. Bass TP: Observations on the misplaced upper canine tooth. Dent Pratt 18: 25-33, 1967. 26. Thilander B, Jakobsson SO: Local factors in impaction of maxillary canines. Acta Odontol Stand 26: 145-168, 1968. 27. Rayne J: The unerupted maxillary canine. Dent Pratt 19: 194-204, 1969. 28. Hitchin AD: The impacted maxillary canine. Br Dent J 100: 1-4, 1956. 29. Nordenram A, Stromberg C: Positional variations of the impacted upper canine. ORAL SURG 22: 711-714, 1966. 30. Cranin AN, Cranin SL: Aiding eruption of maxillary cuspids. Dent Radiogr Photogr 41: 27-34, 1968. 3 I. Lind V: Overkakshorntandens eruptionsproblem. Tandllkartidningen 69: 1066-1074, 1977. 32. Marsh W: Aberrant canines. Dent Pratt Dent Ret 16: 124-126, 1965. 33. Bergstrom K, Carlsson E, H&wing R, JohanssonL, Nilsson J: Transplantation av tinder; en litteraturstudie. Tandllkartidningen 72: 10-16, 1980. 34. Azaz B, Shteyer A: Resorption of the crown in impacted maxillary canine: a clinical, radiographic and histologic study. Int J Oral Surg 7: 167-171, 1978. 35. Gregg JM: Immobilization of the erupting molar in the Syrian hamster. J Dent Res 44: 1219-1226, 1965. 36. Stockdale CR: The relationship of the roots of mandibular third molars to the inferior dental canal. ORAL SURG 12: 1061-1072, 1959. 37. Nitzan D, Keren T, Marmary Y: Does an impacted tooth cause root resorption of the adjacent one? ORAL SURG51: 221-224, 1981. 38. Williams BH: Diagnosis and prevention of maxillary cuspid impaction. Angle Orthod 51: 30-40, 1981. Reprint requests to:
Dr. Lars Rundquist Department of Oral Surgery and Oral Medicine School of Dentistry Carl Gustavs viig 34 S-214 21 MalmB, Sweden
A clinical and radiographic
study
Madeleine Rohlin, D.D.S.. Odont.D.,* and Lars Rundquist, D.D.S.,** Malmii, Sweden SCHOOL
OF DENTISTRY,
UNIVERSITY
OF LUND
When planning autotransplantation of impacted maxillary canines, it is advantageous to know not only the position but also the root anatomy. Radiographic and clinical findings on the root anatomy of 65 impacted maxillary canines were compared. The apices were judged as straight or deflected. The positions of the canines were also recorded. Twenty-eight canines (43%) had a straight and 37 (57%) a deflected apex. The radiographic diagnosis was confirmed in 49 canines, which means a diagnostic accuracy of 75%. The misinterpretation, consisting of seven false-positive and nine false-negative diagnoses, was due to insufficient radiographic examination (7 canines), observation errors (7 canines), and limitations of radiographic examination (2 canines). No association was found between the root anatomy and position. The results show than an optimal radiographic examination and knowledge of any apical deflection are valuable aids to operative assessment of impacted maxillary canines. (ORAL SURG. 58:141-147, 1984)
D
uring the last two decades,several studies have discussedautotransplantation of impacted maxillary canines.‘-” The importance of avoiding surgical trauma to the periodontal membrane for a favorable prognosis was already emphasized in the comprehensive study on transplantation of impacted canines by Widmanlz and has later been confirmed by Andreasen.13It seemsalso to be of utmost importance that the extra-alveolar time for the transplant is as short as possible.*4-‘6This means that the transplant should be transferred to the new alveolus as soon as the preparation is completed. Optimal planning of the surgical procedure is therefore necessary. This is facilitated by accurate evaluation of the position and anatomy of the transplant.2*8’I7 The aim of this study was to compare radiographic and surgical findings on the root anatomy of impacted maxillary canines. In addition, the position of these canines was related to the root anatomy. PATIENTS AND METHODS Patients
Fifty-five consecutive patients referred for autogeneic transplantation (terminology according to Urist18) were collected retrospectively for this study. *Department of Oral Radiology. **Department of Oral Surgery and Oral Medicine.
There were 35 right and 30 left impacted maxillary canines. Table I presents the sex and age distribution of the patients. Clinical examination
Preoperatively, a canine was classified as nonerupted when the tooth had no connection with the oral cavity and as partially erupted when part of the tooth was seen or could be probed from the oral cavity. Radfographic
examination
The routine for examination of impacted maxillary canines consisted of two periapical radiographs and one maxillary axial view. The two periapical radiographs were taken as one orthoradial and one horizontally eccentric radiograph. The routine examination was supplemented with an occlusal view for 28 canines, a tangential view for 11 canines, and hypocycloidal tomography for 2 canines. For 15 canines a panoramic radiograph taken in connection with a complete-mouth examination was also available. The radiographic interpretation of the root anatomy was performed by one of the authors (M.R.). The apex was judged as being straight or deflected. The projection showing the clearest image of the apical region was noted and any signs of deflection were 141
142 Rohlin and Rundquist
Oral Surg. August. I984
Table
I. Sex and age distribution for 55 patients Age (years) Mean age
Sex
1.5-19
6 I
Female Male Total
20-24
(2)
25-29
6
i-
8 (1)
2
A--
8
13
30-34
8 (2) - 7 (1)
15
35-39
40-44
45-49
>49
(wars)
I
1 (1)
2 (1)
1
29
2 3
4 5
0 2
1. 2
33 30
Number of patients with bilateral transplantation of maxillary canines is shown in parentheses.
II. Position of impacted maxillary canines in relation to surgical findings of apical root anatomy (n = 65)
Table
Buccal/lingual
Eruption
position
Angular position
’ Lingual
Straight
apex
Dejected
Vertical Mesioangular I Horizontal
4 14 2
I 15 6
Vertical Mesioangular Vertical Mesioangular
2 4
3 5
I I
3
Vertical I Mesioangular
0 0
2
apex
Nonerupted , Within the dental arch
Partially
I
erupted
Lingual
Within the dental arch
tll. Comparison of surgical and radiographic findings on the apical root anatomy of impacted maxillary canines (n = 65)
Table
Radiographic SurgicalJindings
Straight
Straight apex Deflected apex Total
apex
findings Deflected apex
Total
21
I
28
-9
28
21
30
35
65
Diagnostic accuracy g = 75%.
recorded. The retention level of the crown, buccal/ lingual, and angular positions of the tooth were subgrouped according to the criteria presented by Nordenram.lp Thus, the retention level wasjudged as superficial (coronal to the cervical region of neighboring teeth), medium (between the cervical and apical regions of neighboring teeth) or deep (apical to the neighboring teeth). Also, the position of the crown was classified as buccal, within the dental arch, or lingual. The angular position was classified as vertical, mesioangular, distoangular, or horizontal. surgery
All transplantations were performed by one of the authors (L.R.) with the aid of local anesthesia (48 patients) or general anesthesia (7 patients). During
1
I
the extra-alveolar period the tooth was inspected and the apex was evaluated as straight or deflected. When a deflection was found, the approximate direction in situ was estimated. Comparison findings
between radktgraphic
and surgical
The radiographic and surgical findings were compared. When the radiographic interpretation differed from the surgical findings, the radiographs were studied once more in an attempt to explain the disparity. RESULTS Twenty-eight maxillary canines (43%) presented a straight apex and 37 canines (57%) a deflected apex. There were 15 right and 13 left canines with a straight apex and 20 right and 17 left canines with a deflected apex. Because of the necessity of rotating the canine during surgery, it was extremely difficult to judge the direction of the apical deflection in situ. However, our impression was that most of the deflected apices were mainly buccally deflected. The position of the maxillary canines in relation to the apical root anatomy is presented in Table II. There was no association between position and apical root anatomy of these impacted maxillary canines. Fiftysix canines were nonerupted, and nine were partially erupted. Only one canine was in a superficial posi-
Volume58 Number 2
Apical root anatomy of impacted maxillary canines 143
Fig. 1. Periapical radiographs of an impacted right maxillary canine with a deflected apex. The signs of apical deflection are more evident in A. The superior root surface is positioned close to the wall of the maxillary sinus.
Fig. 2. Periapical radiographs of an impacted left maxillary canine with a deflected apex. A, Note the cross-sectional view of the root canal (arrow). B, Bending of the apical part of the periodontal membrane is seen on the superior root surface.
tion, and the remaining 64 were in a medium position, that is, between the cervical and apical
regions of the lateral incisor. No canine was buccally positioned, 26% of the canines were observed within the dental arch, and 74% were lingually positioned. Most of the canines (68%) were located mesioangularly, and the remaining canines either vertically or horizontally. Table III compares the surgical and radiographic findings on the apical root anatomy. The radiograph-
ic diagnosis was confirmed for 49 canines, representing a diagnostic accuracy of 75%. For 28 canines the radiographic diagnosis was true-positive (deflected apex), and for 21 canines it was true-negative (straight apex). Of the cases with a true-positive diagnosis, 17 canines exhibited an obvious deflection radiographically (Fig. l), whereas only indirect signs of the apical deflection were observed for 11 canines. The indirect signs consisted of bowing of the periodontal membrane, with or without a cross-sectional
144 Rohiin and Rundquist
Oral Surg. August, 1984
Fig. 3. Impacted right maxillary canine. A, Periapical radiograph showing deviation of the periodontal membrane in the superior and apical parts of the root. The deviation was interpreted as a deflection. B, Photograph of the canine shown in A.
Fig. 4. Photograph of a canine showing slight bowing of the apical part of the root.
view of the root canal for six canines (Fig. 2). In another three canines only the periodontal membrane deviated (Fig. 3), and in two canines the apices were diffusely depicted even though the projection and blackening of the radiographs were optimal and revealed surrounding areas clearly. The deflection of the apex was observed in the periapical radiographs in 24 cases. For several canines, however, the deflection was clearly depicted in only one of the periapical radiographs (compare
Fig. 1, A with Fig. 1, B). In three casesthe deflection was seen only in the occlusal view. For one canine only, the tangential view revealed the deflection. For some canines, the panoramic radiographs depicted the deflection when it was shown distinctly in the periapical radiographs. The axial maxillary view did not depict the root anatomy; nor did the lateral tomograms. The disparities between surgical and radiographic findings for 16 canines are presented in Table IV. In four out of seven false-positive diagnoses, a deflection observed radiographically turned out to be a slight bow at inspection (Fig. 4). Among nine falsenegative diagnoses, the defkction was impossible to detect at review in sevencanines (Fig 5). The causes of errors were insufficient examination (seven canines), observation errors (seven canines), and limitations of radiographic examination (two canines). DISCUSSION
After the third molar, the maxillary canine is the tooth that is most frequently impacted, with a reported prevalence of 0.9% to 2%~~~~’Among impacted maxillary canines, 76% to 93% are positioned lingually or within the dental arch and the remainder are displaced buccally.25-30Bucoally displaced maxillary canines can be treated interceptively with a good prognosis, whereas lingually impacted maxillary canines have the least tendency to erupt.26 These facts explain why, in this study, impacted maxillary canines of persons with a mean age of 30
Apical root anatomy of impacted maxillary canines 145
Volume58 Number 2
Fig. 5. Impacted left maxillary canine. A and B, Periapical radiographs of an apex interpreted as straight. C, Photograph of the canine shown in A and B. The apical part of the root is deflected. This false-negative diagnosis was probably due to poor image quality with too low blackening and overaxial projection. Table IV. Disparity
between surgical and radiographic findings on the apex of impacted maxillary canines
(n = 65) No. of canines
SurgicaiJinding
Radiographic finding
Radiographic errors
False-positive False-positive
5
Straight apex
Deflectedapex
2
Straight apex
Deflected apex
5
Deflected apex
Straight apex
False-negative
2 2
Deflected apex Deflected apex
Straight apex Straight apex
False-negative False-negative
Errors
Error obviousat review;observationerror Overaxialx-ray films showingcut apex interpreted as deflection; insufficient examination X-ray films overaxial and too low blackening; insufficient examination Error obvious at review; observation error Impossible to detect deflection even with good
imagequality; limitation of radiographic examination
years and referred for autotransplantation were positioned lingually or within the dental arch. The mesioangular position was seen most frequently, in accordance with observations by Cranin and Cranin30and Lind.3’ According to Marsh,32displacement toward a horizontal position, observed in 32%, might be a result of continued growth of the root. The presence of a deflected apex of impacted canines has previously been only briefly mentioned.8*27’ 33A deflection also seemsto be present in an illustration published by Azaz and Shteyer.34The incidence of apex deflection was high in our study, which might be due to the selection procedure and the criteria used. No exact clinical demarcation between straight and deflected apices was possible since there were intermediate forms. Apices with a gentle bow were classified as straight. It is reason-
able to deduce that the presenceof a deflection of the apex is the result rather than a causeof impaction. In the region where the apical part of the impacted canine is developed, the cortical linings of the nasal cavity and the maxillary sinus, as well as the anterior border of the maxilla, limit a narrow space in the trabecular bone. Since developing roots are plastic and their form seems to be dependent upon the immediate environment,3sthe root apex of impacted maxillary canines might develop a deflection, as shown in Fig. 6. Similarly, for lower third molars the compact bone of the walls of the mandibular canal will not be deflected by developing roots, but the roots in the precalcification stage seek an easier growth course and are deflected by the cana1.36 Moreover, when immobilizing erupting molars of hamsters, Greggs5found that the proliferating apical
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Oral Surg. August, 1984
6. Left maxillary canine. A, Periapical radiograph showing an apex that is not fully mineralized. B, Periapical radiograph 2 years later, revealing a deflection of the apex.
Fig.
dentin appeared to be bent or distorted when the root apex was stabilized. Even though the radiographic anatomy of the maxillary cuspid region is complicated, the present diagnostic accuracy of 75% should be further increased when the diagnostic criteria and major pitfalls for impacted maxillary canines are better known. Most diagnostic errors were due to insufficient radiographic examination or observation errors. Since the study was a retrospective one, the quality of the radiographs was in some casesinsufficient. The radiographs were taken mainly for diagnosis of the position, since the varying apical anatomy was not fully considered at the time of examination. The vertical angulation for the periapical radiographs should be underaxial rather than overaxial. The latter projection will show a shortened root and hide a buccal deflection of the apex. To depict the apex clearly, the image should preferably be projected into the maxillary sinus, avoiding the bony walls of the maxillary sinus and the nasal cavity. Optimal blackening of the radiographs is also of utmost importance. An optimal quality of the radiographs will also facilitate assessmentof root resorption of adjacent teeth, which is reported to occur in 7.5% of cases,37and resorption of the crown of the impacted canine, which occurs in 14%.34 This study indicates that in cases with a root deflection the occlusal as well as the tangential views might be valuable aids to diagnosis. The axial view was applicable only for diagnosing the position of the canine. As no association was found between the apical anatomy and any particular position, the
position could not be used as any indicator of the apical anatomy. The number of observation errors may decrease when more knowledge about the radiographic apical anatomy becomes available. Continuous communication between the radiologist and the surgeon is therefore important so that also indirect, minor radiographic signs of the anatomy are learned. The cross-sectional view of the apical part of the root canal and atypical outline of the periodontal membrane are such signs. Each radiographic examination of nonerupted canines so as to be able to start suitable treatment has been recommended, at the age of 8 to 9 years27. 31.38 or at 11 years.26Later, when the root is fully mineralized, not only a possible deflection of the apex but also diminished eruptive force have to be considered. When orthodontic treatment is not possible or is not accepted by the patient, autotransplantation might be the treatment of choice. In view of the importance of atraumatic removal of the autograft for a good prognosis, a correct radiographic examination would be a prerequisite for the achievement of an optimal clinical result. REFERENCES 1. Simpson W: The reimplanted maxillary canine. Br J Oral Surg 4:150-154, 1959. 2. Moss JP: Autogenous transplantation of maxillary canines. ORAL SURC 26~775-783,1968. 3. Hovinga J: Autotransplantation of maxillary canines: a longterm evaluation. ORAL SURG 27:701-708, 1969. 4. Thonner KE, Meijer M: Autotransplantation of impacted upper canines: a clinical and histologic investigation. Odontol T 77:113-119, 1969.
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5. Thonner KE: Autogenous transplantation of unerupted maxillary canines: a clinical and histologic investigation over five years. Dent Pratt 21:251-257, 1971. 6. Cook RM: The current status of autogenous transplantation as applied to the maxillary canine. Int Dent J 22: 286-300, 1972. 7. Lovius BBJ, Atherton JD. Wynne THM, Finch LD: Br J Orthod 1: 27-33 1974. 8. Oksala E: Autotransplantation of vital maxillary canines: a clinical and radiographic study. Proc Finn Dent Sot 70: Suppl. 1, 1974. 9. McCay C: The unerupted maxillary canine: an assement of the role of surgery in 2,500 treated cases. Br Dent J 145: 207-210, 1978. 10. Kristerson L, Kvint S: Autotransplantation av tander-10 Brs erfarenheter. Tandlakartidningen 73: 598-606, 1981. 1 I. Hardy P: The autogenous transplantation of maxillary canines. Br Dent J 153: 183-186, 1982. 12. Widman L: Om transplantation av retinerade horntinder. Sven Tandlakartidn 8: 131-160, 1915. 13. Andreasen JO: Relationship between cell damages in the periodontal ligament after replantation and subsequentdevelopment of root resorption. Acta Odontol Stand 39: 15-25, 1981. 14. Andreasen JO, Hjglrting-Hansen E, Jdlst 0: A clinical and radiographic study of 76 autotransplanted third molars. Stand J Dent Res 78: 512-523, 1970. 15. Hansen J, Fibaeck B: Clinical experience of auto- and allotransplantation of teeth. Int Dent J 22: 270-285, 1972. 16. Andreasen JO: The effect of extra-alveolar period and storage media upon periodontal and pulpal healing after replantation of mature permanent incisors in monkeys. Int J Oral Surg 10: 43-53, 1981. 17. Andreasen JO, Hjdrting-Hansen E: Replantation and autotransplantation of teeth. Trans Congr Int Assoc Oral Surg, pp. 430-433, 1970. 18. Urist MR: Bone transplants and implants. In Fundamental and clinical bone physiology, Philadelphia, 1980,J. B. Lippincott Company, pp. 331-368. 19. Nordenram A: Retinerade tinder. In Hjdrting-Hansen L, Nordenram A, Aas E (editors): Oral kirurgi, ed 2, Copenhagen, 1978, Munksgaard, pp. 184-188. 20. Cramer HC: Dental survey of one thousand adult males: a statistical study correlated with physical and laboratory findings. J Am Dent Assoc 16: 122-128, 1929. 21. Rohrer A: Displaced and impacted canines. Int J Orthod 15: 1002-1020. 1929.
22. Mead SV: Incidence of impacted teeth. Int J Orthod 16: 885-890, 1930. 23. Baden E: Surgical management of unerupted canines and premolars. ORAL SURG 9: 141-192, 1956. 24. Dachi SF, Howell FV: A survey of 3,874 routine full-mouth radiographs. II. A study of impacted teeth. ORAL SURG 14: 1165-1169, 1961.
25. Bass TP: Observations on the misplaced upper canine tooth. Dent Pratt 18: 25-33, 1967. 26. Thilander B, Jakobsson SO: Local factors in impaction of maxillary canines. Acta Odontol Stand 26: 145-168, 1968. 27. Rayne J: The unerupted maxillary canine. Dent Pratt 19: 194-204, 1969. 28. Hitchin AD: The impacted maxillary canine. Br Dent J 100: 1-4, 1956. 29. Nordenram A, Stromberg C: Positional variations of the impacted upper canine. ORAL SURG 22: 711-714, 1966. 30. Cranin AN, Cranin SL: Aiding eruption of maxillary cuspids. Dent Radiogr Photogr 41: 27-34, 1968. 3 I. Lind V: Overkakshorntandens eruptionsproblem. Tandllkartidningen 69: 1066-1074, 1977. 32. Marsh W: Aberrant canines. Dent Pratt Dent Ret 16: 124-126, 1965. 33. Bergstrom K, Carlsson E, H&wing R, JohanssonL, Nilsson J: Transplantation av tinder; en litteraturstudie. Tandllkartidningen 72: 10-16, 1980. 34. Azaz B, Shteyer A: Resorption of the crown in impacted maxillary canine: a clinical, radiographic and histologic study. Int J Oral Surg 7: 167-171, 1978. 35. Gregg JM: Immobilization of the erupting molar in the Syrian hamster. J Dent Res 44: 1219-1226, 1965. 36. Stockdale CR: The relationship of the roots of mandibular third molars to the inferior dental canal. ORAL SURG 12: 1061-1072, 1959. 37. Nitzan D, Keren T, Marmary Y: Does an impacted tooth cause root resorption of the adjacent one? ORAL SURG51: 221-224, 1981. 38. Williams BH: Diagnosis and prevention of maxillary cuspid impaction. Angle Orthod 51: 30-40, 1981. Reprint requests to:
Dr. Lars Rundquist Department of Oral Surgery and Oral Medicine School of Dentistry Carl Gustavs viig 34 S-214 21 MalmB, Sweden