- Email: [email protected]
Eruption prediction of mandibular premolars associated with dentigerous cysts
Eruption prediction of mandibular premolars associated with dentigerous cysts Yoshie Yahara, DDS,a Yasutaka Kubota, DDS, PhD,b Takahiro Yamashiro, DDS, PhD,c and Kanemitsu Shirasuna, DDS, PhD,d Fukuoka, Japan KYUSHU UNIVERSITY
Objective. A tooth with a dentigerous cyst (DC) does not always erupt by marsupialization. The eruption duration and conditions of DC-associated premolars were examined to predict such eruption following marsupialization. Study design. The eruption and conditions including depth, root formation, inclination, and eruption space were examined retrospectively in 21 DC-associated mandibular premolars using dental and panoramic radiograms. Results. Fifteen of 21 premolars erupted half within 3 months and all 15 erupted completely within 10 months after marsupialization, without orthodontic traction. The age of the patients, tooth depth, and inclination were significantly different between the erupted and non-erupted groups, whereas there was no significant difference in the root formation or the eruption space between the 2 groups. Conclusions. The successful eruption of a DC-associated premolar can be predicted within 3 months after marsupialization. Furthermore, the eruption may be affected by the patient’s age, tooth depth, and tooth inclination. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009;108:28-31)
A dentigerous cyst (DC) is one of the most common odontogenic jaw cysts. The cyst encloses the crown of an impacted tooth in the cystic cavity and the cyst wall attaches to the neck of the tooth. DCs are commonly found associated with the mandibular second premolar, except for the maxillary canine and the third molars.1 The cyst generally grows in the jaws without pain and the cyst-associated tooth is commonly displaced. There are 2 principal surgical methods for the treatment of DC. One is the enucleation of the cyst wall with a cyst-associated tooth and the other is marsupialization that creates a surgical window into the cavity of the cyst. The marsupialization for DC has been widely recommended in order to avoid making a marked bone defect in the jaw and decreasing the patient’s quality of life.2 Furthermore, the marsupialization has the advantage of promoting the eruption of a DC-associated tooth and preserving the tooth without orthodontic traction.3-7 An impacted tooth associated with a DC, however, does not always successfully erupt follow-
ing marsupialization. It was reported that 81% of DC-associated mandibular premolars and 36% of maxillary canines successfully erupted about 100 days after marsupialization without orthodontic traction.8 The orthodontic traction of the tooth should be considered to provide the ideal dental arch, if the impacted tooth does not erupt following marsupialization. It is, therefore, clinically important to predict whether a DC-associated tooth will successfully erupt during marsupialization. The eruption speed of a DC-associated tooth and the conditions including the age of patient, tooth depth, dental root maturity, tooth inclination, and eruption space have been investigated.6-8 The information, however, is very limited and the factors that affect the successful eruption of an impacted tooth associated with a DC are unclear. This study examined the duration of DC-associated premolar eruption and evaluated the factors that affected the eruption after marsupialization, including the age of the patients, tooth depth, dental root formation, tooth inclination, and eruption space.
a
PATIENTS AND METHODS Twenty-one DC-associated mandibular premolars that had been marsupialized at Kyushu University Dental Hospital were retrospectively analyzed after obtaining informed consent from the patients (12 males and 9 females; mean age 10.8 ⫾ 2.7 years). The cysts were diagnosed as DCs based on the clinical, radiographic, and pathological findings. The eruption of impacted premolars associated with DCs after marsupialization was evaluated by dental radiographs that were taken after marsupialization.
Postgraduate student, Department of Oral and Maxillofacial Surgery, Graduate School of Dental Science, Kyushu University, Japan. b Lecturer, Department of Oral and Maxillofacial Surgery, Graduate School of Dental Science, Kyushu University, Japan. c Clinical Fellow, Department of Oral and Maxillofacial Surgery, Graduate School of Dental Science, Kyushu University, Japan. d Professor and Chairman, Department of Oral and Maxillofacial Surgery, Graduate School of Dental Science, Kyushu University, Japan. Received for publication Sep 19, 2008; returned for revision Jan 6, 2009; accepted for publication Feb 5, 2009. 1079-2104/$ - see front matter © 2009 Published by Mosby, Inc. doi:10.1016/j.tripleo.2009.02.001
28
OOOOE Volume 108, Number 1
Fig. 1. Measurement of the conditions of a DC-associated premolar in a panoramic radiogram. The tooth depth, dental root formation, tooth inclination, and eruption space were evaluated before marsupialization by a panoramic radiogram taken at the first visit to the hospital. a and a’, the enamel junction of the adjacent teeth; b and b’, root apex of the adjacent teeth; c, central point of a DC-associated tooth crown; d and e, angle of the inclination and the long axis of a DC-associated tooth, respectively.
When the upper tip of the cusp of an impacted DCassociated tooth erupted to the line that passes the cement-enamel junction of the adjacent teeth or reached the occlusal plane, the eruption was evaluated as half (score 0.5) or complete (score 1.0). The conditions of the impacted tooth, including tooth depth, the level of dental root formation, tooth inclination, and eruption space for the tooth were evaluated before marsupialization by panoramic radiograms that were taken at the first visit to the hospital (Fig. 1). Tooth depth was classified into 2 groups, type S and type D. When the central point of the impacted tooth crown was shallower than the line that passes the one half root of the adjacent teeth, the tooth was defined as type S. When the point was deeper, the tooth was defined as type D. The level of dental root formation was divided into 2 groups, stage E (root length ⬍ crown height) and stage F (root length ⱖ crown height) according to the previous report by Wasserstein et al.9 Tooth inclination of a DC-associated tooth was measured by the angle between the long axis of the tooth and the line that passes the cement-enamel junction of the adjacent teeth. The long axis of DC-associated premolars was suitable for bucco-lingual direction in 4 of 21 DCs, and it was impossible to measure the tooth inclination in such cases (Fig. 2, a). Therefore, tooth inclination was measured in 17 impacted premolars. The eruption space was measured by the ratio of the
Yahara et al. 29
Fig. 2. Panoramic radiograms of 2 cases of DC-associated mandibular second premolars successfully erupted after marsupialization. DC-associated mandibular second premolars on the right (a) and left (c) sides erupted after marsupialization (b, d). The radiograms were taken before (a, c) and 20 (b) or 9 (d) months after marsupialization.
distance between both contact points of the adjacent teeth to the crown width of the DC-associated tooth.8 The data are expressed as the mean ⫾ SD. Statistical significance was assessed using the 2-test or MannWhitney U test. P values of less than .05 were considered to be significant. RESULTS In 21 mandibular premolars associated with DCs, 15 teeth (71.4%) erupted half within 3 months (mean duration; 2.2 ⫾ 0.7 months) after marsupialization and all these teeth erupted completely within 10 months (mean duration: 5.8 ⫾ 2.8 months) (Fig. 2). On the other hand, the other 6 impacted teeth, which did not erupt half within 3 months, did not successfully erupt even 12 months after marsupialization (Fig. 3). The mean age of the patients whose DC-associated premolars erupted successfully was 9.8 ⫾ 2.1 years (n ⫽ 15), which was significantly younger than that of the patients (13.2 ⫾ 2.8 years; n ⫽ 6) of the nonerupted group (Table I). The tooth depth was type S in 14 of 15 erupted premolars (93.3%), whereas it was type D in 4 of 6 nonerupted ones (66.6%), indicating that the depth of the erupted group was significantly shallower than that of the nonerupted group (P ⫽ .0114). Tooth inclination was measured in 12 erupted and 5 nonerupted premolars. The angle of the erupted and nonerupted groups was 60.2 ⫾ 19.6° (n ⫽ 12) and 26.6 ⫾ 21.7° (n ⫽ 5), respectively. There was a significant difference between the values (P ⫽ .0176). In dental root forma-
30
OOOOE July 2009
Yahara et al.
Fig. 3. The effect of marsupialization on the eruption period of the impacted premolars associated with DCs. The eruption of a DC-associated premolar was evaluated by dental radiograms as half (0.5) or complete (1.0) when the upper tip of the cusp or the cement-enamel junction of the impacted tooth was at the line that passes the cement-enamel junction of the adjacent teeth. Closed and open circles indicate erupted and nonerupted teeth, respectively.
Table I. Conditions of erupted and nonerupted premolars associated with DCs Premolars (n ⫽ 21)
Age, y Tooth depth Type S Type D Root formation Stage E Stage F Eruption space/ Crown width Tooth inclination*
Erupted (n ⫽ 15)
Non-erupted (n ⫽ 6)
9.8 ⫾ 2.1
13.2 ⫾ 2.8
P values .0128
14 1
2 4
9 6 1.08 ⫾ 0.36
5 1 1.14 ⫾ 0.12
.5850
62.6 ⫾ 19.6°
26.6 ⫾ 21.7°
.0176
.0114
.6126
*Tooth inclination was measured in 12 erupted and 5 nonerupted premolars, respectively. DC, dentigerous cyst.
tion, 6 of 15 erupted premolars (40.0%) and 1 of 6 nonerupted ones (16.7%) showed immature root formation and were stage F. There was no significant difference in the dental root formation between the erupted and nonerupted groups. The ratio of eruption space to the crown width in the erupted group was 1.08 ⫾ 0.36 (n ⫽ 15) and the values were not significantly different from those of the nonerupted group (1.14 ⫾ 0.12; n ⫽ 6) (Table I).
DISCUSSION Marsupialization is the minimal surgical intervention for the treatment of a DC and also has advantages in promoting the eruption of a DC-associated tooth without orthodontic traction.2,3,5-7 An impacted tooth associated with DC, however, does not always erupt following the marsupialization. In the present study, 71.4% of DC-associated mandibular premolars successfully erupted without orthodontic traction within 5.8 ⫾ 2.8 months after marsupialization. This value is similar to that of a previous report that showed the successful eruption in 81% of DC-associated mandibular premolars in about 100 days after marsupialization.8 Interestingly, when a DC-associated tooth did not erupt half within 3 months after marsupialization, none of the tooth successfully erupted even if the marsupialization was continued for 12 months. The eruption speed of a DC-associated tooth has been shown to decrease rapidly within the first 3 months after marsupialization.6 Therefore, these findings suggest that the successful eruption of a DC-associated premolar without orthodontic traction may be predicted 3 months after marsupialization. It is important to determine the conditions that affect the eruption of a DC-associated tooth to predict the successful eruption before marsupialization. In this study, the mean age of the patients with the successfully erupted premolars after marsupialization was 9.8 ⫾ 2.1 years (7⬃14 years). These values were significantly younger than that of the nonerupted cases with a deviation from 11 to 16 years. Previous studies have also indicated that the age of patient affects the successful eruption of a DC-associated premolar,7,8 as shown in the spontaneous eruption of an impacted permanent tooth after the extraction of the supernumerary tooth.10 The cutoff value of patient age less than 10 years has been shown to be a significant parameter for prediction of the eruption.7 Furthermore, it has been reported that the tooth depth of the DC-associated premolars is a crucial factor for the successful eruption.7,8 The current data also showed that the depth of a DC-associated tooth in the erupted group was significantly shallower than that in the nonerupted group. Therefore, both the age of a patient and the depth of a DC-associated tooth are important factors associated with the successful eruption of a DC-associated premolar after marsupialization. The effect of dental root maturation on the eruption of a DC-associated tooth remains controversial. As shown in a noncystic permanent tooth,11 the dental root maturation was reported to be one of crucial factors affecting the tooth eruption in a DC-associated mandibular premolar.2,8 In this study, however, there was no significant difference in the dental root formation
OOOOE Volume 108, Number 1
between erupted and nonerupted premolars. This finding is supported by other data that showed no significant relationship between eruption speed and dental root formation in DC-associated second premolars.6 Tominaga et al.12 also reported that the successful eruption of a DC-associated tooth was independent of the maturation of the dental root. The level of the dental root formation was classified into 2 groups, less than the crown height and equal to or greater than the crown height, because it is difficult to evaluate the dental root maturation precisely by panoramic radiograms. The difference in the evaluation methods for the dental root maturation might cause the different results. Further studies are needed to clarify the effect of dental root maturation on the eruption of DC-associated premolars. The angle of the long axis of DC-associated premolars against the line that passes the cement-enamel junction of the adjacent teeth (60.2 ⫾ 19.6°) was significantly larger than that of nonerupted ones, whereas the ratio of the eruption space to the crown width of the impacted premolars was not significantly different from that of the nonerupted ones. A DC is classified into the central and lateral types according to the location of the cyst against the DC-associated tooth,3 and the eruption of a DC-associated tooth might be more expected in the central type independent of the inclination of the DCassociated tooth.12 In the current cases, however, the central type was detected in 7 of 12 (58.3%) erupted and in 2 of 5 (40.0%) nonerupted teeth and there was no significant difference between the values (data not shown). Therefore, a small inclination of a DC-associated premolar (⬎ 60°) may be an important factor that affects the eruption of a DC-associated tooth as shown by previous reports7,8 rather than the location of the cyst against the enclosed tooth. Although the eruption space/tooth size was reported to be significantly larger than that in the nonerupted group,7 authors in the same institute reported that the eruption space/tooth size did not relate to the eruption, not only in DC-associated mandibular premolars but also in DC-associated maxillary canines.8 Therefore, the ratio of eruption space to the size of a DC-associated premolar may not affect its eruption. In conclusion, the successful eruption of DC-associated premolars without orthodontic traction may be predicted 3 months after marsupialization. The age of the patients, tooth depth, and inclination, but neither the
Yahara et al. 31
dental root formation nor the eruption space affect such eruptions. REFERENCES 1. Kramer IRH, Pindborg JJ, Shear M. Histological typing of odontogenic tumours. 2nd ed. World Health Organization. Berlin: Springer-Verlag; 1992. 2. Ertas U, Yavuz MS. Interesting eruption of 4 teeth associated with a large dentigerous cyst in mandible by only marsupialization. J Oral Maxillofac Surg 2003;61:728-30. 3. Thoma KH. Oral surgery II, 5th ed. St. Louis: Mosby Co.; 1969. p. 891–904. 4. Ziccardi VB, Eggleston TI, Schneider RE. Using fenestration technique to treat a large dentigerous cyst. J Am Dent Assoc 1997;128:201-5. 5. Takagi S, Koyama S. Guided eruption of an impacted second premolar associated with a dentigerous cyst in the maxillary sinus of a 6-year-old child. J Oral Maxillofac Surg 1998;56: 237-9. 6. Miyawaki S, Hyomoto M, Tsubouchi J, Kirita T, Sugimura M. Eruption speed and rate of angulation change of a cyst-associated mandibular second premolar after marsupialization of a dentigerous cyst. Am J Orthod Dentofacial Orthop 1999;116:578-84. 7. Fujii R, Kawakami M, Hyomoto M, Ishida J, Kirita T. Panoramic findings for predicting eruption of mandibular premolars associated with dentigerous cyst after marsupialization. J Oral Maxillofac Surg 2008;66:272-6. 8. Hyomoto M, Kawakami M, Inoue M, Kirita T. Clinical conditions for eruption of maxillary canines and mandibular premolars associated with dentigerous cysts. Am J Orthod Dentofacial Orthop 2003;124:515-20. 9. Wasserstein A, Brezniak N, Shalish M, Heller M, Rakocz M. Angular changes and their rates in concurrence to developmental stages of the mandibular second premolar. Angle Orthod 2004; 74:332-6. 10. Leyland L, Batra P, Wong F, Llewelyn R. A retrospective evaluation of the eruption of impacted permanent incisors after extraction of supernumerary teeth. J Clin Pediatr Dent 2006;30: 225-31. 11. Grøn AM. Prediction of tooth emergence. J Dent Res 1961; 41:573-85. 12. Tominaga K, Kikuta T, Fukuda J, Uemura S, Yasumitsu C, Yamada N, et al. Marsupialization for dentigerous cysts in children– especially behaviors of the involved teeth. Jpn J Oral Maxillofac Surg 1988;34:1957-62. Reprint requests: Yasutaka Kubota, DDS, PhD Department of Oral and Maxillofacial Surgery Graduate School of Dental Science Kyushu University 3-1-1 Maidashi, Higashi-ku Fukuoka 812-8582, Japan [email protected]
Objective. A tooth with a dentigerous cyst (DC) does not always erupt by marsupialization. The eruption duration and conditions of DC-associated premolars were examined to predict such eruption following marsupialization. Study design. The eruption and conditions including depth, root formation, inclination, and eruption space were examined retrospectively in 21 DC-associated mandibular premolars using dental and panoramic radiograms. Results. Fifteen of 21 premolars erupted half within 3 months and all 15 erupted completely within 10 months after marsupialization, without orthodontic traction. The age of the patients, tooth depth, and inclination were significantly different between the erupted and non-erupted groups, whereas there was no significant difference in the root formation or the eruption space between the 2 groups. Conclusions. The successful eruption of a DC-associated premolar can be predicted within 3 months after marsupialization. Furthermore, the eruption may be affected by the patient’s age, tooth depth, and tooth inclination. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009;108:28-31)
A dentigerous cyst (DC) is one of the most common odontogenic jaw cysts. The cyst encloses the crown of an impacted tooth in the cystic cavity and the cyst wall attaches to the neck of the tooth. DCs are commonly found associated with the mandibular second premolar, except for the maxillary canine and the third molars.1 The cyst generally grows in the jaws without pain and the cyst-associated tooth is commonly displaced. There are 2 principal surgical methods for the treatment of DC. One is the enucleation of the cyst wall with a cyst-associated tooth and the other is marsupialization that creates a surgical window into the cavity of the cyst. The marsupialization for DC has been widely recommended in order to avoid making a marked bone defect in the jaw and decreasing the patient’s quality of life.2 Furthermore, the marsupialization has the advantage of promoting the eruption of a DC-associated tooth and preserving the tooth without orthodontic traction.3-7 An impacted tooth associated with a DC, however, does not always successfully erupt follow-
ing marsupialization. It was reported that 81% of DC-associated mandibular premolars and 36% of maxillary canines successfully erupted about 100 days after marsupialization without orthodontic traction.8 The orthodontic traction of the tooth should be considered to provide the ideal dental arch, if the impacted tooth does not erupt following marsupialization. It is, therefore, clinically important to predict whether a DC-associated tooth will successfully erupt during marsupialization. The eruption speed of a DC-associated tooth and the conditions including the age of patient, tooth depth, dental root maturity, tooth inclination, and eruption space have been investigated.6-8 The information, however, is very limited and the factors that affect the successful eruption of an impacted tooth associated with a DC are unclear. This study examined the duration of DC-associated premolar eruption and evaluated the factors that affected the eruption after marsupialization, including the age of the patients, tooth depth, dental root formation, tooth inclination, and eruption space.
a
PATIENTS AND METHODS Twenty-one DC-associated mandibular premolars that had been marsupialized at Kyushu University Dental Hospital were retrospectively analyzed after obtaining informed consent from the patients (12 males and 9 females; mean age 10.8 ⫾ 2.7 years). The cysts were diagnosed as DCs based on the clinical, radiographic, and pathological findings. The eruption of impacted premolars associated with DCs after marsupialization was evaluated by dental radiographs that were taken after marsupialization.
Postgraduate student, Department of Oral and Maxillofacial Surgery, Graduate School of Dental Science, Kyushu University, Japan. b Lecturer, Department of Oral and Maxillofacial Surgery, Graduate School of Dental Science, Kyushu University, Japan. c Clinical Fellow, Department of Oral and Maxillofacial Surgery, Graduate School of Dental Science, Kyushu University, Japan. d Professor and Chairman, Department of Oral and Maxillofacial Surgery, Graduate School of Dental Science, Kyushu University, Japan. Received for publication Sep 19, 2008; returned for revision Jan 6, 2009; accepted for publication Feb 5, 2009. 1079-2104/$ - see front matter © 2009 Published by Mosby, Inc. doi:10.1016/j.tripleo.2009.02.001
28
OOOOE Volume 108, Number 1
Fig. 1. Measurement of the conditions of a DC-associated premolar in a panoramic radiogram. The tooth depth, dental root formation, tooth inclination, and eruption space were evaluated before marsupialization by a panoramic radiogram taken at the first visit to the hospital. a and a’, the enamel junction of the adjacent teeth; b and b’, root apex of the adjacent teeth; c, central point of a DC-associated tooth crown; d and e, angle of the inclination and the long axis of a DC-associated tooth, respectively.
When the upper tip of the cusp of an impacted DCassociated tooth erupted to the line that passes the cement-enamel junction of the adjacent teeth or reached the occlusal plane, the eruption was evaluated as half (score 0.5) or complete (score 1.0). The conditions of the impacted tooth, including tooth depth, the level of dental root formation, tooth inclination, and eruption space for the tooth were evaluated before marsupialization by panoramic radiograms that were taken at the first visit to the hospital (Fig. 1). Tooth depth was classified into 2 groups, type S and type D. When the central point of the impacted tooth crown was shallower than the line that passes the one half root of the adjacent teeth, the tooth was defined as type S. When the point was deeper, the tooth was defined as type D. The level of dental root formation was divided into 2 groups, stage E (root length ⬍ crown height) and stage F (root length ⱖ crown height) according to the previous report by Wasserstein et al.9 Tooth inclination of a DC-associated tooth was measured by the angle between the long axis of the tooth and the line that passes the cement-enamel junction of the adjacent teeth. The long axis of DC-associated premolars was suitable for bucco-lingual direction in 4 of 21 DCs, and it was impossible to measure the tooth inclination in such cases (Fig. 2, a). Therefore, tooth inclination was measured in 17 impacted premolars. The eruption space was measured by the ratio of the
Yahara et al. 29
Fig. 2. Panoramic radiograms of 2 cases of DC-associated mandibular second premolars successfully erupted after marsupialization. DC-associated mandibular second premolars on the right (a) and left (c) sides erupted after marsupialization (b, d). The radiograms were taken before (a, c) and 20 (b) or 9 (d) months after marsupialization.
distance between both contact points of the adjacent teeth to the crown width of the DC-associated tooth.8 The data are expressed as the mean ⫾ SD. Statistical significance was assessed using the 2-test or MannWhitney U test. P values of less than .05 were considered to be significant. RESULTS In 21 mandibular premolars associated with DCs, 15 teeth (71.4%) erupted half within 3 months (mean duration; 2.2 ⫾ 0.7 months) after marsupialization and all these teeth erupted completely within 10 months (mean duration: 5.8 ⫾ 2.8 months) (Fig. 2). On the other hand, the other 6 impacted teeth, which did not erupt half within 3 months, did not successfully erupt even 12 months after marsupialization (Fig. 3). The mean age of the patients whose DC-associated premolars erupted successfully was 9.8 ⫾ 2.1 years (n ⫽ 15), which was significantly younger than that of the patients (13.2 ⫾ 2.8 years; n ⫽ 6) of the nonerupted group (Table I). The tooth depth was type S in 14 of 15 erupted premolars (93.3%), whereas it was type D in 4 of 6 nonerupted ones (66.6%), indicating that the depth of the erupted group was significantly shallower than that of the nonerupted group (P ⫽ .0114). Tooth inclination was measured in 12 erupted and 5 nonerupted premolars. The angle of the erupted and nonerupted groups was 60.2 ⫾ 19.6° (n ⫽ 12) and 26.6 ⫾ 21.7° (n ⫽ 5), respectively. There was a significant difference between the values (P ⫽ .0176). In dental root forma-
30
OOOOE July 2009
Yahara et al.
Fig. 3. The effect of marsupialization on the eruption period of the impacted premolars associated with DCs. The eruption of a DC-associated premolar was evaluated by dental radiograms as half (0.5) or complete (1.0) when the upper tip of the cusp or the cement-enamel junction of the impacted tooth was at the line that passes the cement-enamel junction of the adjacent teeth. Closed and open circles indicate erupted and nonerupted teeth, respectively.
Table I. Conditions of erupted and nonerupted premolars associated with DCs Premolars (n ⫽ 21)
Age, y Tooth depth Type S Type D Root formation Stage E Stage F Eruption space/ Crown width Tooth inclination*
Erupted (n ⫽ 15)
Non-erupted (n ⫽ 6)
9.8 ⫾ 2.1
13.2 ⫾ 2.8
P values .0128
14 1
2 4
9 6 1.08 ⫾ 0.36
5 1 1.14 ⫾ 0.12
.5850
62.6 ⫾ 19.6°
26.6 ⫾ 21.7°
.0176
.0114
.6126
*Tooth inclination was measured in 12 erupted and 5 nonerupted premolars, respectively. DC, dentigerous cyst.
tion, 6 of 15 erupted premolars (40.0%) and 1 of 6 nonerupted ones (16.7%) showed immature root formation and were stage F. There was no significant difference in the dental root formation between the erupted and nonerupted groups. The ratio of eruption space to the crown width in the erupted group was 1.08 ⫾ 0.36 (n ⫽ 15) and the values were not significantly different from those of the nonerupted group (1.14 ⫾ 0.12; n ⫽ 6) (Table I).
DISCUSSION Marsupialization is the minimal surgical intervention for the treatment of a DC and also has advantages in promoting the eruption of a DC-associated tooth without orthodontic traction.2,3,5-7 An impacted tooth associated with DC, however, does not always erupt following the marsupialization. In the present study, 71.4% of DC-associated mandibular premolars successfully erupted without orthodontic traction within 5.8 ⫾ 2.8 months after marsupialization. This value is similar to that of a previous report that showed the successful eruption in 81% of DC-associated mandibular premolars in about 100 days after marsupialization.8 Interestingly, when a DC-associated tooth did not erupt half within 3 months after marsupialization, none of the tooth successfully erupted even if the marsupialization was continued for 12 months. The eruption speed of a DC-associated tooth has been shown to decrease rapidly within the first 3 months after marsupialization.6 Therefore, these findings suggest that the successful eruption of a DC-associated premolar without orthodontic traction may be predicted 3 months after marsupialization. It is important to determine the conditions that affect the eruption of a DC-associated tooth to predict the successful eruption before marsupialization. In this study, the mean age of the patients with the successfully erupted premolars after marsupialization was 9.8 ⫾ 2.1 years (7⬃14 years). These values were significantly younger than that of the nonerupted cases with a deviation from 11 to 16 years. Previous studies have also indicated that the age of patient affects the successful eruption of a DC-associated premolar,7,8 as shown in the spontaneous eruption of an impacted permanent tooth after the extraction of the supernumerary tooth.10 The cutoff value of patient age less than 10 years has been shown to be a significant parameter for prediction of the eruption.7 Furthermore, it has been reported that the tooth depth of the DC-associated premolars is a crucial factor for the successful eruption.7,8 The current data also showed that the depth of a DC-associated tooth in the erupted group was significantly shallower than that in the nonerupted group. Therefore, both the age of a patient and the depth of a DC-associated tooth are important factors associated with the successful eruption of a DC-associated premolar after marsupialization. The effect of dental root maturation on the eruption of a DC-associated tooth remains controversial. As shown in a noncystic permanent tooth,11 the dental root maturation was reported to be one of crucial factors affecting the tooth eruption in a DC-associated mandibular premolar.2,8 In this study, however, there was no significant difference in the dental root formation
OOOOE Volume 108, Number 1
between erupted and nonerupted premolars. This finding is supported by other data that showed no significant relationship between eruption speed and dental root formation in DC-associated second premolars.6 Tominaga et al.12 also reported that the successful eruption of a DC-associated tooth was independent of the maturation of the dental root. The level of the dental root formation was classified into 2 groups, less than the crown height and equal to or greater than the crown height, because it is difficult to evaluate the dental root maturation precisely by panoramic radiograms. The difference in the evaluation methods for the dental root maturation might cause the different results. Further studies are needed to clarify the effect of dental root maturation on the eruption of DC-associated premolars. The angle of the long axis of DC-associated premolars against the line that passes the cement-enamel junction of the adjacent teeth (60.2 ⫾ 19.6°) was significantly larger than that of nonerupted ones, whereas the ratio of the eruption space to the crown width of the impacted premolars was not significantly different from that of the nonerupted ones. A DC is classified into the central and lateral types according to the location of the cyst against the DC-associated tooth,3 and the eruption of a DC-associated tooth might be more expected in the central type independent of the inclination of the DCassociated tooth.12 In the current cases, however, the central type was detected in 7 of 12 (58.3%) erupted and in 2 of 5 (40.0%) nonerupted teeth and there was no significant difference between the values (data not shown). Therefore, a small inclination of a DC-associated premolar (⬎ 60°) may be an important factor that affects the eruption of a DC-associated tooth as shown by previous reports7,8 rather than the location of the cyst against the enclosed tooth. Although the eruption space/tooth size was reported to be significantly larger than that in the nonerupted group,7 authors in the same institute reported that the eruption space/tooth size did not relate to the eruption, not only in DC-associated mandibular premolars but also in DC-associated maxillary canines.8 Therefore, the ratio of eruption space to the size of a DC-associated premolar may not affect its eruption. In conclusion, the successful eruption of DC-associated premolars without orthodontic traction may be predicted 3 months after marsupialization. The age of the patients, tooth depth, and inclination, but neither the
Yahara et al. 31
dental root formation nor the eruption space affect such eruptions. REFERENCES 1. Kramer IRH, Pindborg JJ, Shear M. Histological typing of odontogenic tumours. 2nd ed. World Health Organization. Berlin: Springer-Verlag; 1992. 2. Ertas U, Yavuz MS. Interesting eruption of 4 teeth associated with a large dentigerous cyst in mandible by only marsupialization. J Oral Maxillofac Surg 2003;61:728-30. 3. Thoma KH. Oral surgery II, 5th ed. St. Louis: Mosby Co.; 1969. p. 891–904. 4. Ziccardi VB, Eggleston TI, Schneider RE. Using fenestration technique to treat a large dentigerous cyst. J Am Dent Assoc 1997;128:201-5. 5. Takagi S, Koyama S. Guided eruption of an impacted second premolar associated with a dentigerous cyst in the maxillary sinus of a 6-year-old child. J Oral Maxillofac Surg 1998;56: 237-9. 6. Miyawaki S, Hyomoto M, Tsubouchi J, Kirita T, Sugimura M. Eruption speed and rate of angulation change of a cyst-associated mandibular second premolar after marsupialization of a dentigerous cyst. Am J Orthod Dentofacial Orthop 1999;116:578-84. 7. Fujii R, Kawakami M, Hyomoto M, Ishida J, Kirita T. Panoramic findings for predicting eruption of mandibular premolars associated with dentigerous cyst after marsupialization. J Oral Maxillofac Surg 2008;66:272-6. 8. Hyomoto M, Kawakami M, Inoue M, Kirita T. Clinical conditions for eruption of maxillary canines and mandibular premolars associated with dentigerous cysts. Am J Orthod Dentofacial Orthop 2003;124:515-20. 9. Wasserstein A, Brezniak N, Shalish M, Heller M, Rakocz M. Angular changes and their rates in concurrence to developmental stages of the mandibular second premolar. Angle Orthod 2004; 74:332-6. 10. Leyland L, Batra P, Wong F, Llewelyn R. A retrospective evaluation of the eruption of impacted permanent incisors after extraction of supernumerary teeth. J Clin Pediatr Dent 2006;30: 225-31. 11. Grøn AM. Prediction of tooth emergence. J Dent Res 1961; 41:573-85. 12. Tominaga K, Kikuta T, Fukuda J, Uemura S, Yasumitsu C, Yamada N, et al. Marsupialization for dentigerous cysts in children– especially behaviors of the involved teeth. Jpn J Oral Maxillofac Surg 1988;34:1957-62. Reprint requests: Yasutaka Kubota, DDS, PhD Department of Oral and Maxillofacial Surgery Graduate School of Dental Science Kyushu University 3-1-1 Maidashi, Higashi-ku Fukuoka 812-8582, Japan [email protected]