Anterior maxillary supernumerary teeth: A clinical and radiographic study Thomas von Arx, DMD*
Key words: Mesiodens, radiography, supernumerary teeth.
Abstract Clinical records and radiographs of 90 patients with 113 anterior maxillary supernumerary teeth (mesiodens) have been evaluated. Although uncommon, mesiodentes are the most frequent supernumerary teeth and may disturb the eruption and/or position of the adjacent permanent incisors. Clinical and radiographic examination may disclose the number, direction and location of mesiodentes and their effects on neighbouring teeth. In the present study the majority of the supernumerary teeth lay palatal to the central incisors. Complete or partial eruption of a mesiodens was rare, hence the importance of radiographs to locate supernumerary teeth in the premaxilla. Pathological findings included the formation of dentigerous cysts in three patients and complete ossification of the pericoronal space with resorption of the crown of the mesiodentes in eight cases. Retention and malposition of the adjacent permanent incisors occurred in 39 and 24 cases, respectively. (Received for publication November 1990. Revised March 1991. Accepted May 1991.)
Introduction The aim of the present study was to investigate the clinical and radiographic features associated with anterior maxillary supernumerary teeth in 90
*Formerly at Department of Oral and Maxillofacial Surgery, Kantonsspital, Lucerne, Switzerland. Australian Dental Journal 1992;37:(3):189-95
patients at the Department of Oral and Maxillofacia1 Surgery in a Swiss Hospital. Epidemiological studies report an incidence of up to 5 per cent for supernumerary teeth in the permanent dentiti~n.'.~Ninety per cent of these teeth were found in the m a ~ i l l aThe . ~ incidence of mesiodentes has been reported to range from 0.15 to 4 per ~ e n t .Mesiodens ~-~ prevalence in males is twice as frequent as in fern ale^.',^,^,^,^ The aetiology of supernumerary teeth i, essentially unknown. Originally Bolk'O proposed that mesiodentes were a phylogenetic relict (six incisors). A second theory described a splitting of the tooth bud (dich~tomy).~," Today the most supported theory of aetiology is a hyperactivity of the dental lamina.4,'2 The factors which are responsible for such hyperactivity might be tensions within the jaws as well as the mobility of particular facial processes which result in dental lamina splitting." Furthermore, a genetic factor is emphasized because of familial mesiodens ~ c c u r r e n c e .Mesiodentes ~,~ are usually small and short with triangular or conical crown shapes. Because of their smallness, they normally cannot be detected by palpation. Clinical symptoms caused by mesiodentes are also very rare except that delayed eruption (Fig. 1) or disturbance of alignment of the permanent upper incisors occurs (Fig. 2). They are consequently detected in radiog r a p h ~ . ' . ' ~ -Unilateral '~ persistence of a deciduous incisor, retention or ectopic eruption of a permanent incisor, a wide diastema or rotation or inclination of erupted permanent incisors may be due to anterior maxillary supernumerary teeth. Radiological findings include cyst formation, pericoronal space or progressive external resorption of the crown (Fig. 3).8 This crown resorption is more common and more severe in older age groups, and if removal of the mesiodens is indicated, it becomes increasingly diffi~u1t.l~ Formation of a dentigerous cyst associated with a mesiodens is 189
Fig. 1.-Persistence of a deciduous central incisor and retention of the permanent central incisor caused by a mesiodens. Fig. 2.-Alignment disturbance of both permanent central incisors due to a mesiodens.
p o ~ s i b l e . ' ~Resorption .'~ of the adjacent roots by a mesiodens may occur, but is extremely r a ~ e . ~ . ~ The radiographic examination is important to assess the number and location or displacement of a mesiodens. A maxillary occlusal radiograph is highly recommended for all children with dental disturbances in the prema~illa.~ Periapical radiographs utilizing a parallax technique can help in establishing a palatal or buccal location of the mesiodens. The use of the panoramic radiograph is limited because of the thin focal trough in the anterior dental region.2o In two-thirds of the cases only one mesiodens is present, but in the remainder multiple supernumerary teeth occur (Fig. 3, 4). Most mesiodentes are located palatally to the permanent incisors. Only a few lie in the dental arch or labially to the permanent incisor^.^,'^ The incidence of retention of a mesiodens ranges from 75 to 90 per ~ e n t . ~The , ~ direction .~ of the long axis of the mesiodens is either normal (downward) (Fig. 1) or inverted (upward) (Fig. 5); in a few cases it is horizontal (Fig. 6).8,19 Because of these clinical and radiological findings it is recommended that mesiodentes be removed ~urgically.~ Iatrogenic damage to adjacent perman190
ent incisor roots has been reported, but intra- or post-operative complications are very rare, especially if removal is performed during childhood or adolescence.2 . 9
Materials and methods The population studies consisted of 90 patients who had been examined or treated because of anterior maxillary supernumerary teeth at the Department of Oral and Maxillofacial Surgery, Kantonsspital, Lucerne, Switzerland, between 1977 and 1989. The patients were either referred to the hospital for removal of supernumerary anterior teeth or a mesiodens was found accidentally during routine radiographic examination. The patient records and the radiographs were evaluated and the following features were studied. Patient variables Age and sex distribution. Number of mesiodentes per patient. Condition of mesiodens Clinical symptoms. Stage of eruption. Direction and location. Australian Dental Journal 1992;37:3.
Fig. 3. -Case with three supernumerary maxillary front teeth. Inverted mesiodens with progressive crown resorption. Retention of permanent left central incisor caused by overlying mesiodens. A further mesiodens is completely erupted mesial to the lateral left incisor. Fig. 4.-Case with two supernumerary front teeth. The inverted mesiodens has an enlarged pericoronal space. Fig. 5.-Inverted mesiodens causing a central diastema and pushing aside the incisive suture. Fig. 6. - Horizontally-transverse positioned mesiodens with a large dentigerous cyst. Australian Dental Journal 1992;37:3
191
40
30
20
10
n "
-5 -10 -15 -20 -25 -30 -35 -40 -45 -50 -55 -60 -65 -70 YEARS
MALES
FEMALES
Fig. 7.-Age and sex distribution of 90 patients with Supernumerary maxillary anterior teeth.
................ Buccal location
9
8%
Location in the dental arch
6
5%
.............
..........
Palatal location
I
98
Total
113
87%
100%
Fig. 8.-Location of 113 supernumerary maxillary anterior teeth in relation to the dental arch.
Width of pericoronal space. External crown resorption. Effects on neighbouring teeth Retention of permanent incisors. Malposition of permanent incisors. Root resorption of permanent incisors. Central or lateral diastema formation.
Table 1.
Number of mesiodensper patient
Number of mesiodens 1 2 3 4 Total
Number of cases* 70 18 1 1 90
(78) (20) (1) (1) (100)
Total of mesiodentes 70 36 3 4 113
'Percentage in parenthesis.
Results Patient variables Between 1977 and 1989, 113 anterior maxillary supernumerary teeth were diagnosed in 90 patients. The age and sex distribution is shown in Fig. 7. There were 65 male and 25 female patients with a sex ratio of 2.6 to 1. The predominant age group 192
was from six to ten years of age. A majority of 78 per cent had only one supernumerary tooth. In 20 per cent of the cases two mesiodentes were present. Two cases (2 per cent) had multiple occurrences with three and four mesiodentes respectively (Table 1)Australian Dental Journal 1992;37:3.
Table 2.
Degree of mesiodens eruption
Degree of eruption Impacted Partially erupted Completely erupted Total
No.* 106 (94) 2 (2) 5 (4) 113 (100)
+Percentage in parenthesis.
Normal (non-inverted) Inverted Horizontal-transverse Horizontal-sagittal Total
No.*
No space visible Space smaller than 2 mm Space between 2 and 5 mm Space larger than 5 mm Total
9 (8) 92 (86) 3 (3) 3 (3) 1077 (100)
No.* 50 (44) 42 (37) 12 ( 1 1 ) 9 (8) 113 (100)
*Percentage in parenthesis
Condition of the mesiodens Clinical symptoms associated with a mesiodens were found only in two cases. One patient complained of pressure pain at the incisive papilla and another of sustained infection of a large dentigerous cyst associated with a mesiodens. The degree of eruption and the direction of the 113 mesiodentes are shown in Tables 2 and 3. Ninetyfour per cent of the supernumerary teeth remained completely embedded. The commonest direction of the long axis of the mesiodens was a normal downward position (44 per cent). Figure 8 shows the location of the supernumerary teeth with a majority (87 per cent) lying palatally to the dental arch. The distribution of the width of the pericoronal space as a variable for cystic transformation of the follicle is given in Table 4. A normal width (less than 2 mm) was found in 86 per cent of cases. Three mesiodentes presented a widened pericoronal space (2 to 5 mm) and another three cases had large dentigerous cysts (diameters 13, 16 and 24 mm) associated with the mesiodentes. Eight of nine teeth with complete absence of the pericoronal space showed external crown resorption with seven of these patients being older than 40 years. Effects on neighbouring teeth A total of 39 permanent incisors in 26 patients had not erupted because of the supernumerary teeth. Malposition of the neighbouring permanent incisors in reference to the long axis of the tooth occurred as tooth rotation in 13 cases and as tooth inclination in 11 cases (Table 5). Ten central and two lateral diastemata were caused by mesiodentes. Australian Dental Journal 1992;37:3.
Width of pericoronal space
*Percentage in parenthesis. tSix mesiodentes out of 113 were excluded because of partial or complete tooth eruption.
Table 3. Position of mesiodens Position
Table 4. Distribution of width of radiographic pericoronal space
Table 5. Effects on permanent upper incisors Effect* Tooth retention Root resorption Tooth rotation Tooth inclination Central diastema Lateral diastema
39 none 13 11 10 2
*Multiple effects possible per case.
Resorption of adjacent roots by an unerupted supernumerary tooth was not seen radiographically.
Discussion In this study a ma1e:female ratio of 2.6:l for the prevalence for anterior maxillary supernumerary teeth was found. This was slightly higher than the average sex ratio stated in the literature of 2:1.1.2.6.8.9 The predominance of children between 6 and 10 years in the present study can be explained by the fact that the children at this age were specifically referred to the hospital for surgical removal of the supernumerary teeth. An accidental finding of a mesiodens was more frequent in older patients when the supernumerary teeth were seen on radiographs taken for other reasons. Multiple occurrence of supernumerary anterior teeth is reported in the l i t e r a t ~ r e to ~ . range ~ . ~ from 8 to 27 per cent of mesiodens cases compared with 22 per cent in the present study. A triple or quadruple occurrence is extremely rare, but two corresponding cases were seen in patients in the present study. The location and the position of the mesiodentes were similar to those of Bodin et al.' who examined 350 supernumerary anterior teeth in 290 patients. Dentigerous cyst formation is another problem associated with unerupted supernumerary anterior teeth. Primosch4 reported an enlarged follicular sac in 30 per cent of the cases, but histological evidence 193
of cyst formation in only 4 to 9 per cent. In the present study only three cases presented with a widened pericoronal space and another three had developed dentigerous cysts. This relative infrequency may be explained by the fact that most supernumerary teeth had been diagnosed and extracted before cystic transformation of the follicle could take place. Bodin et a1.' found a significantly higher frequency of pathologically widened follicles in adult patients. On the other hand, the pericoronal space of a mesiodens may disappear completely because of a degeneration of the follicle and consequent bony apposition. Stafne17emphasized that following degeneration of the enamel epithelium, the enamel comes in contact with connective tissue which can produce progressive resorption of the embedded crown. This is confirmed by the study by Bodin, Julin and Thomsson,8 who found a strong correlation between the lack of pericoronal space and crown resorption of supernumerary anterior teeth. Furthermore he reported that crown resorption was more common and more severe in older age groups. In the present study, all patients in whom crown resorption was evident were older than 40 years of age and the involved teeth showed a complete absence of the pericoronal space in the radiographs. The percentages reported in the literature4.'." for retention of adjacent incisors (59 per cent), malposition (48 per cent) and diastema formation (15 per cent) are higher than those reported in the present study. This can be partially explained by the fact that most of the referred children had undergone orthodontic pre-treatment before examination and surgical removal of the mesiodens at this hospital. The results of this clinical and radiographic study of anterior maxillary supernumerary teeth underline the necessity for early detection and appropriate treatment of these supernumerary teeth. The wide range of effects on neighbouring teeth include the following features: retention or delayed eruption of permanent incisors, axial rotation or inclination of erupted permanent incisors, formation of diastemas and cyst development. As a consequence of these clinical implications, it is recommended that mesiodentes be removed surgically. Koch, Schwartz and Klausen19 advocated that symptomless supernumerary teeth may be followed clinically and radiographically without surgical removal but the majority of a ~ t h o r s ~agree . ~ . ' that ~ extraction is the indicated treatment for these supernumerary teeth. Controversy exists as to when to remove a mesiodens. Some prefer an immediate surgical removal after diagnosis to permit spontaneous 194
eruption of the permanent incisors and to avoid possible orthodontic problem^.^,'^ Others prefer a delayed approach in order to avoid iatrogenic damage to the developing adjacent teeth.*I
Conclusions (1) A radiographic screening of the premaxilla using an occlusal radiograph is recommended for all children at the age of six years in order to detect supernumerary anterior teeth. (2) If permanent incisors are retained or their eruption is disturbed, a radiographic check-up with an occlusal radiograph must be undertaken. (3) The same requirement applies to cases of malposition of permanent incisors or diastema formation. (4) Supernumerary anterior teeth should be extracted in children and adolescents in order to avoid possible effects on neighbouring teeth andor cyst development. (5) An immediate surgical removal after diagnosis of a mesiodens is indicated because intra- or postoperative complications are less likely to occur in younger patients. (6) If a supernumerary tooth cannot be located exactly in relation to the dental arch, a palatal approach should primarily be chosen for the surgical approach. If necessary a buccal flap may be raised secondarily. (7) In adults a careful evaluation of the indication for surgical removal is necessary considering the increasing difficulty of removing an impacted and ankylosed supernumerary anterior tooth with external resorption. References 1. Hennis I, Lotz G, Schienbein H. Die Zahnueberzahl im Oberkiefer-Frontzahngebiet unter besonderer Beruecksichtigung der Odontoide (I). Quintessenz 1983;34: 1961-70. 2. Hennis I, Lotz G, Schienbein H. Die Zahnueberzahl im Oberkiefer-Frontzahngebiet unter besonderer Beruecksichtigung der Odontoide (11). Quintessenz Ibid.,2167-76. 3. Schroeder HE. Pathobiologie oraler Strukturen. Basle: Karger, 1983. 4. Primosch RE. Anterior supernumerary teeth - assessment and surgical intervention in children. Pediatr Dent 1981;3:204-15. 5. Hurlen B, Humerfelt D. Characteristics of premaxillary hyperodontia. A radiographic study. Acta Odontol Scan 1985;43:75-81. 6. Kaler LC. Prevalence of mesiodens in a pediatric Hispanic population. J Dent Child 1988;55:137-8. 7. Konchak PA, Lanigan DT. The management of impacted maxillary incisors secondary to supernumeraries. Oral Health 1985;75:59-61. Australian Dental Journal 1992;37:3.
8. Bodin I, Julin P, Thomsson M. Hyperodontia 111. Supernumerary anterior teeth. Dentomaxillofac Radio1 1981;1035-42. 9. Hoegstroem A, Anderson L. Complications related to surgical removal of anterior supernumerary teeth in children. J Dent Child 1987;54:341-3. 10. Bolk L. Die ueberzaehligen oberen Inzisivi des Menschen. Dtsch Monatsschr Zahnheilk 1917;35: 185-228. 1 1. Sedano H, Gorlin R. Familial Occurrence of mesiodens. Oral Surg Oral Med Oral Pathol 1969;27:360-2. 12. Knychalska-Karwan Z, Pawlicki R, Jakob-Dolezal K, Kanvan T . The mesiodens teeth under an electron scanning microscope and X-ray microanalyzer. J Int Assoc Dent Child 1984;15:7-13. 13. Cangialosi TJ. Management of a maxillary central incisor impacted by a supernumerary tooth. J Am Dent Assoc 1982;105:8 12-4. 14. Munns D. Unerupted incisors. Br J Orthod 1981;8:39-42. 15. Tay F, Pang A, Yuen S. Unerupted maxillary anterior supernumerary teeth: report of 204 cases. ASDC J Dent Child 1984;51:289-94. 16. Witsenburg B, Boering G. Eruption of impacted permanent upper incisors after removal of supernumerary teeth. Int J Oral Surg 1981; 10:423-31.
Australian Dental Journal 1992;37:3.
17. Stafne EC, Gibilisco JA. Oral roentgenographic diagnosis. 4th edn. Philadelphia: Saunders, 1975. 18. Fischer-Brandies E, Bunnag T. Mesiodens und Zyste. Quntessenz 1982;33:1345-8. 19. Koch H, Schwartz 0, Klausen B. Indications of surgical removal of supernumerary teeth in the premaxilla. Int J Oral Maxillofac Surg 1986;15:273-81. 20. Matteson SR, Lupton CR, Morrison WS. Effect of panoramic focal trough topography on radiographic imaging of supernumerary teeth in the anterior region. J Oral Maxillofac Surg 1982;40:318-9. 21. Hotz RP. Orthodontie in der taeglichen. Praxis. Bern: Huber, 1980.
Address for correspondenceheprints: Abt G r Mund-Kiefer-Gesichts-Chirurgie, Kantonsspital, CH-6006 Luzern 16, Switzerland.
195
Key words: Mesiodens, radiography, supernumerary teeth.
Abstract Clinical records and radiographs of 90 patients with 113 anterior maxillary supernumerary teeth (mesiodens) have been evaluated. Although uncommon, mesiodentes are the most frequent supernumerary teeth and may disturb the eruption and/or position of the adjacent permanent incisors. Clinical and radiographic examination may disclose the number, direction and location of mesiodentes and their effects on neighbouring teeth. In the present study the majority of the supernumerary teeth lay palatal to the central incisors. Complete or partial eruption of a mesiodens was rare, hence the importance of radiographs to locate supernumerary teeth in the premaxilla. Pathological findings included the formation of dentigerous cysts in three patients and complete ossification of the pericoronal space with resorption of the crown of the mesiodentes in eight cases. Retention and malposition of the adjacent permanent incisors occurred in 39 and 24 cases, respectively. (Received for publication November 1990. Revised March 1991. Accepted May 1991.)
Introduction The aim of the present study was to investigate the clinical and radiographic features associated with anterior maxillary supernumerary teeth in 90
*Formerly at Department of Oral and Maxillofacial Surgery, Kantonsspital, Lucerne, Switzerland. Australian Dental Journal 1992;37:(3):189-95
patients at the Department of Oral and Maxillofacia1 Surgery in a Swiss Hospital. Epidemiological studies report an incidence of up to 5 per cent for supernumerary teeth in the permanent dentiti~n.'.~Ninety per cent of these teeth were found in the m a ~ i l l aThe . ~ incidence of mesiodentes has been reported to range from 0.15 to 4 per ~ e n t .Mesiodens ~-~ prevalence in males is twice as frequent as in fern ale^.',^,^,^,^ The aetiology of supernumerary teeth i, essentially unknown. Originally Bolk'O proposed that mesiodentes were a phylogenetic relict (six incisors). A second theory described a splitting of the tooth bud (dich~tomy).~," Today the most supported theory of aetiology is a hyperactivity of the dental lamina.4,'2 The factors which are responsible for such hyperactivity might be tensions within the jaws as well as the mobility of particular facial processes which result in dental lamina splitting." Furthermore, a genetic factor is emphasized because of familial mesiodens ~ c c u r r e n c e .Mesiodentes ~,~ are usually small and short with triangular or conical crown shapes. Because of their smallness, they normally cannot be detected by palpation. Clinical symptoms caused by mesiodentes are also very rare except that delayed eruption (Fig. 1) or disturbance of alignment of the permanent upper incisors occurs (Fig. 2). They are consequently detected in radiog r a p h ~ . ' . ' ~ -Unilateral '~ persistence of a deciduous incisor, retention or ectopic eruption of a permanent incisor, a wide diastema or rotation or inclination of erupted permanent incisors may be due to anterior maxillary supernumerary teeth. Radiological findings include cyst formation, pericoronal space or progressive external resorption of the crown (Fig. 3).8 This crown resorption is more common and more severe in older age groups, and if removal of the mesiodens is indicated, it becomes increasingly diffi~u1t.l~ Formation of a dentigerous cyst associated with a mesiodens is 189
Fig. 1.-Persistence of a deciduous central incisor and retention of the permanent central incisor caused by a mesiodens. Fig. 2.-Alignment disturbance of both permanent central incisors due to a mesiodens.
p o ~ s i b l e . ' ~Resorption .'~ of the adjacent roots by a mesiodens may occur, but is extremely r a ~ e . ~ . ~ The radiographic examination is important to assess the number and location or displacement of a mesiodens. A maxillary occlusal radiograph is highly recommended for all children with dental disturbances in the prema~illa.~ Periapical radiographs utilizing a parallax technique can help in establishing a palatal or buccal location of the mesiodens. The use of the panoramic radiograph is limited because of the thin focal trough in the anterior dental region.2o In two-thirds of the cases only one mesiodens is present, but in the remainder multiple supernumerary teeth occur (Fig. 3, 4). Most mesiodentes are located palatally to the permanent incisors. Only a few lie in the dental arch or labially to the permanent incisor^.^,'^ The incidence of retention of a mesiodens ranges from 75 to 90 per ~ e n t . ~The , ~ direction .~ of the long axis of the mesiodens is either normal (downward) (Fig. 1) or inverted (upward) (Fig. 5); in a few cases it is horizontal (Fig. 6).8,19 Because of these clinical and radiological findings it is recommended that mesiodentes be removed ~urgically.~ Iatrogenic damage to adjacent perman190
ent incisor roots has been reported, but intra- or post-operative complications are very rare, especially if removal is performed during childhood or adolescence.2 . 9
Materials and methods The population studies consisted of 90 patients who had been examined or treated because of anterior maxillary supernumerary teeth at the Department of Oral and Maxillofacial Surgery, Kantonsspital, Lucerne, Switzerland, between 1977 and 1989. The patients were either referred to the hospital for removal of supernumerary anterior teeth or a mesiodens was found accidentally during routine radiographic examination. The patient records and the radiographs were evaluated and the following features were studied. Patient variables Age and sex distribution. Number of mesiodentes per patient. Condition of mesiodens Clinical symptoms. Stage of eruption. Direction and location. Australian Dental Journal 1992;37:3.
Fig. 3. -Case with three supernumerary maxillary front teeth. Inverted mesiodens with progressive crown resorption. Retention of permanent left central incisor caused by overlying mesiodens. A further mesiodens is completely erupted mesial to the lateral left incisor. Fig. 4.-Case with two supernumerary front teeth. The inverted mesiodens has an enlarged pericoronal space. Fig. 5.-Inverted mesiodens causing a central diastema and pushing aside the incisive suture. Fig. 6. - Horizontally-transverse positioned mesiodens with a large dentigerous cyst. Australian Dental Journal 1992;37:3
191
40
30
20
10
n "
-5 -10 -15 -20 -25 -30 -35 -40 -45 -50 -55 -60 -65 -70 YEARS
MALES
FEMALES
Fig. 7.-Age and sex distribution of 90 patients with Supernumerary maxillary anterior teeth.
................ Buccal location
9
8%
Location in the dental arch
6
5%
.............
..........
Palatal location
I
98
Total
113
87%
100%
Fig. 8.-Location of 113 supernumerary maxillary anterior teeth in relation to the dental arch.
Width of pericoronal space. External crown resorption. Effects on neighbouring teeth Retention of permanent incisors. Malposition of permanent incisors. Root resorption of permanent incisors. Central or lateral diastema formation.
Table 1.
Number of mesiodensper patient
Number of mesiodens 1 2 3 4 Total
Number of cases* 70 18 1 1 90
(78) (20) (1) (1) (100)
Total of mesiodentes 70 36 3 4 113
'Percentage in parenthesis.
Results Patient variables Between 1977 and 1989, 113 anterior maxillary supernumerary teeth were diagnosed in 90 patients. The age and sex distribution is shown in Fig. 7. There were 65 male and 25 female patients with a sex ratio of 2.6 to 1. The predominant age group 192
was from six to ten years of age. A majority of 78 per cent had only one supernumerary tooth. In 20 per cent of the cases two mesiodentes were present. Two cases (2 per cent) had multiple occurrences with three and four mesiodentes respectively (Table 1)Australian Dental Journal 1992;37:3.
Table 2.
Degree of mesiodens eruption
Degree of eruption Impacted Partially erupted Completely erupted Total
No.* 106 (94) 2 (2) 5 (4) 113 (100)
+Percentage in parenthesis.
Normal (non-inverted) Inverted Horizontal-transverse Horizontal-sagittal Total
No.*
No space visible Space smaller than 2 mm Space between 2 and 5 mm Space larger than 5 mm Total
9 (8) 92 (86) 3 (3) 3 (3) 1077 (100)
No.* 50 (44) 42 (37) 12 ( 1 1 ) 9 (8) 113 (100)
*Percentage in parenthesis
Condition of the mesiodens Clinical symptoms associated with a mesiodens were found only in two cases. One patient complained of pressure pain at the incisive papilla and another of sustained infection of a large dentigerous cyst associated with a mesiodens. The degree of eruption and the direction of the 113 mesiodentes are shown in Tables 2 and 3. Ninetyfour per cent of the supernumerary teeth remained completely embedded. The commonest direction of the long axis of the mesiodens was a normal downward position (44 per cent). Figure 8 shows the location of the supernumerary teeth with a majority (87 per cent) lying palatally to the dental arch. The distribution of the width of the pericoronal space as a variable for cystic transformation of the follicle is given in Table 4. A normal width (less than 2 mm) was found in 86 per cent of cases. Three mesiodentes presented a widened pericoronal space (2 to 5 mm) and another three cases had large dentigerous cysts (diameters 13, 16 and 24 mm) associated with the mesiodentes. Eight of nine teeth with complete absence of the pericoronal space showed external crown resorption with seven of these patients being older than 40 years. Effects on neighbouring teeth A total of 39 permanent incisors in 26 patients had not erupted because of the supernumerary teeth. Malposition of the neighbouring permanent incisors in reference to the long axis of the tooth occurred as tooth rotation in 13 cases and as tooth inclination in 11 cases (Table 5). Ten central and two lateral diastemata were caused by mesiodentes. Australian Dental Journal 1992;37:3.
Width of pericoronal space
*Percentage in parenthesis. tSix mesiodentes out of 113 were excluded because of partial or complete tooth eruption.
Table 3. Position of mesiodens Position
Table 4. Distribution of width of radiographic pericoronal space
Table 5. Effects on permanent upper incisors Effect* Tooth retention Root resorption Tooth rotation Tooth inclination Central diastema Lateral diastema
39 none 13 11 10 2
*Multiple effects possible per case.
Resorption of adjacent roots by an unerupted supernumerary tooth was not seen radiographically.
Discussion In this study a ma1e:female ratio of 2.6:l for the prevalence for anterior maxillary supernumerary teeth was found. This was slightly higher than the average sex ratio stated in the literature of 2:1.1.2.6.8.9 The predominance of children between 6 and 10 years in the present study can be explained by the fact that the children at this age were specifically referred to the hospital for surgical removal of the supernumerary teeth. An accidental finding of a mesiodens was more frequent in older patients when the supernumerary teeth were seen on radiographs taken for other reasons. Multiple occurrence of supernumerary anterior teeth is reported in the l i t e r a t ~ r e to ~ . range ~ . ~ from 8 to 27 per cent of mesiodens cases compared with 22 per cent in the present study. A triple or quadruple occurrence is extremely rare, but two corresponding cases were seen in patients in the present study. The location and the position of the mesiodentes were similar to those of Bodin et al.' who examined 350 supernumerary anterior teeth in 290 patients. Dentigerous cyst formation is another problem associated with unerupted supernumerary anterior teeth. Primosch4 reported an enlarged follicular sac in 30 per cent of the cases, but histological evidence 193
of cyst formation in only 4 to 9 per cent. In the present study only three cases presented with a widened pericoronal space and another three had developed dentigerous cysts. This relative infrequency may be explained by the fact that most supernumerary teeth had been diagnosed and extracted before cystic transformation of the follicle could take place. Bodin et a1.' found a significantly higher frequency of pathologically widened follicles in adult patients. On the other hand, the pericoronal space of a mesiodens may disappear completely because of a degeneration of the follicle and consequent bony apposition. Stafne17emphasized that following degeneration of the enamel epithelium, the enamel comes in contact with connective tissue which can produce progressive resorption of the embedded crown. This is confirmed by the study by Bodin, Julin and Thomsson,8 who found a strong correlation between the lack of pericoronal space and crown resorption of supernumerary anterior teeth. Furthermore he reported that crown resorption was more common and more severe in older age groups. In the present study, all patients in whom crown resorption was evident were older than 40 years of age and the involved teeth showed a complete absence of the pericoronal space in the radiographs. The percentages reported in the literature4.'." for retention of adjacent incisors (59 per cent), malposition (48 per cent) and diastema formation (15 per cent) are higher than those reported in the present study. This can be partially explained by the fact that most of the referred children had undergone orthodontic pre-treatment before examination and surgical removal of the mesiodens at this hospital. The results of this clinical and radiographic study of anterior maxillary supernumerary teeth underline the necessity for early detection and appropriate treatment of these supernumerary teeth. The wide range of effects on neighbouring teeth include the following features: retention or delayed eruption of permanent incisors, axial rotation or inclination of erupted permanent incisors, formation of diastemas and cyst development. As a consequence of these clinical implications, it is recommended that mesiodentes be removed surgically. Koch, Schwartz and Klausen19 advocated that symptomless supernumerary teeth may be followed clinically and radiographically without surgical removal but the majority of a ~ t h o r s ~agree . ~ . ' that ~ extraction is the indicated treatment for these supernumerary teeth. Controversy exists as to when to remove a mesiodens. Some prefer an immediate surgical removal after diagnosis to permit spontaneous 194
eruption of the permanent incisors and to avoid possible orthodontic problem^.^,'^ Others prefer a delayed approach in order to avoid iatrogenic damage to the developing adjacent teeth.*I
Conclusions (1) A radiographic screening of the premaxilla using an occlusal radiograph is recommended for all children at the age of six years in order to detect supernumerary anterior teeth. (2) If permanent incisors are retained or their eruption is disturbed, a radiographic check-up with an occlusal radiograph must be undertaken. (3) The same requirement applies to cases of malposition of permanent incisors or diastema formation. (4) Supernumerary anterior teeth should be extracted in children and adolescents in order to avoid possible effects on neighbouring teeth andor cyst development. (5) An immediate surgical removal after diagnosis of a mesiodens is indicated because intra- or postoperative complications are less likely to occur in younger patients. (6) If a supernumerary tooth cannot be located exactly in relation to the dental arch, a palatal approach should primarily be chosen for the surgical approach. If necessary a buccal flap may be raised secondarily. (7) In adults a careful evaluation of the indication for surgical removal is necessary considering the increasing difficulty of removing an impacted and ankylosed supernumerary anterior tooth with external resorption. References 1. Hennis I, Lotz G, Schienbein H. Die Zahnueberzahl im Oberkiefer-Frontzahngebiet unter besonderer Beruecksichtigung der Odontoide (I). Quintessenz 1983;34: 1961-70. 2. Hennis I, Lotz G, Schienbein H. Die Zahnueberzahl im Oberkiefer-Frontzahngebiet unter besonderer Beruecksichtigung der Odontoide (11). Quintessenz Ibid.,2167-76. 3. Schroeder HE. Pathobiologie oraler Strukturen. Basle: Karger, 1983. 4. Primosch RE. Anterior supernumerary teeth - assessment and surgical intervention in children. Pediatr Dent 1981;3:204-15. 5. Hurlen B, Humerfelt D. Characteristics of premaxillary hyperodontia. A radiographic study. Acta Odontol Scan 1985;43:75-81. 6. Kaler LC. Prevalence of mesiodens in a pediatric Hispanic population. J Dent Child 1988;55:137-8. 7. Konchak PA, Lanigan DT. The management of impacted maxillary incisors secondary to supernumeraries. Oral Health 1985;75:59-61. Australian Dental Journal 1992;37:3.
8. Bodin I, Julin P, Thomsson M. Hyperodontia 111. Supernumerary anterior teeth. Dentomaxillofac Radio1 1981;1035-42. 9. Hoegstroem A, Anderson L. Complications related to surgical removal of anterior supernumerary teeth in children. J Dent Child 1987;54:341-3. 10. Bolk L. Die ueberzaehligen oberen Inzisivi des Menschen. Dtsch Monatsschr Zahnheilk 1917;35: 185-228. 1 1. Sedano H, Gorlin R. Familial Occurrence of mesiodens. Oral Surg Oral Med Oral Pathol 1969;27:360-2. 12. Knychalska-Karwan Z, Pawlicki R, Jakob-Dolezal K, Kanvan T . The mesiodens teeth under an electron scanning microscope and X-ray microanalyzer. J Int Assoc Dent Child 1984;15:7-13. 13. Cangialosi TJ. Management of a maxillary central incisor impacted by a supernumerary tooth. J Am Dent Assoc 1982;105:8 12-4. 14. Munns D. Unerupted incisors. Br J Orthod 1981;8:39-42. 15. Tay F, Pang A, Yuen S. Unerupted maxillary anterior supernumerary teeth: report of 204 cases. ASDC J Dent Child 1984;51:289-94. 16. Witsenburg B, Boering G. Eruption of impacted permanent upper incisors after removal of supernumerary teeth. Int J Oral Surg 1981; 10:423-31.
Australian Dental Journal 1992;37:3.
17. Stafne EC, Gibilisco JA. Oral roentgenographic diagnosis. 4th edn. Philadelphia: Saunders, 1975. 18. Fischer-Brandies E, Bunnag T. Mesiodens und Zyste. Quntessenz 1982;33:1345-8. 19. Koch H, Schwartz 0, Klausen B. Indications of surgical removal of supernumerary teeth in the premaxilla. Int J Oral Maxillofac Surg 1986;15:273-81. 20. Matteson SR, Lupton CR, Morrison WS. Effect of panoramic focal trough topography on radiographic imaging of supernumerary teeth in the anterior region. J Oral Maxillofac Surg 1982;40:318-9. 21. Hotz RP. Orthodontie in der taeglichen. Praxis. Bern: Huber, 1980.
Address for correspondenceheprints: Abt G r Mund-Kiefer-Gesichts-Chirurgie, Kantonsspital, CH-6006 Luzern 16, Switzerland.
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