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Delayed eruption of first molars due to immature tooth formation: Report of five cases
PEDIATRIC DENTAL JOURNAL 16(2): 184–186, 2006 184
Case Report
Delayed eruption of first molars due to immature tooth formation: Report of five cases Kaori Nishio, Kazuhiko Nakano, Atsuko Murakami and Takashi Ooshima Department of Pediatric Dentistry, Osaka University Graduate School of Dentistry 1-8 Yamada-oka, Suita, Osaka 565-0871, JAPAN
Abstract Five cases of delayed eruption of the first molars due to immature tooth formation are presented. Three cases involved a teeth in a single quadrant, two of which were the maxillary left region while the other was in the maxillary right region. Both the maxillary left and right regions were affected in one case, and all four molar regions were affected in another case. Dental age was calculated by evaluating the tooth developmental stage in each case, and was compared with chronological age (CA). The mean dental age, excluding the affected molar region (MD), was compared with the dental age of the affected tooth (DA). The CA was more than 1 SD older than the MD in four cases. When we considered the affected molars to be first permanent molars, DA was 1.51– 2.43 years younger than MD in all five cases, while DA was approximately 1.07–2.39 years older than MD when the affected molars were considered as second permanent molars. These results indicated that the developmental stages of the affected molars were between that of the first and second molars, and were estimated to have emerged into oral cavity at an age between 9 and 10 years old.
Introduction Delayed eruption of first permanent molars is occasionally encountered, which is generally caused by ectopic eruption, impaction on the distal aspect of the primary second molars, or the presence of a physical barrier like an odontoma impeding the eruption pathway1). The tooth root is usually approximately one half to two thirds of its final length at the time of gingival emergence2) and delayed development of a tooth can be one of the causes for its delayed eruption. In our previous study, analysis of 353 orthopantomographs of child patients revealed nine cases of immature tooth formation of a single first molar, when the results were compared with the developmental status of all of the other first permanent molars3). The major characteristics of those cases were that the affected Received on January 6, 2006 Accepted on May 16, 2006
184
Key words Chronological age, Delayed eruption, Dental age, First molar, Second molar
teeth tended to erupt between the ages of 9 and 10 years, and showed an occlusal morphology similar to second molars rather than first molars. Furthermore, only one or two molars were identified in the affected quadrants of these patients, while the congenital absence of other permanent teeth were an additional complication in several of the cases. In the present study, we report five cases of retarded eruption of first molars due to immature tooth formation identified in our clinic in 2005. Three cases showed involvement of a single region and two had multiple quadrant involvement.
Case Reports Five patients with delayed eruption of the first molar were identified from orthopantomographic examinations conducted in the spring and summer of 2005 at the Pedodontics Clinic of Osaka University Dental Hospital. The Table 1 shows a summary of these five cases. All were females and their chronological
DELAYED ERUPTION OF M1 DUE TO IMMATURE TOOTH FORMATION
185
Table 1 Analysis of cases with retarded eruption due to immature tooth development Case no.
Gender
Affected molars*
Chronological age (CA) (years)
Mean dental age of premolar and molar region excluding affected tooth (MD) [MeanⳲSD (years)]
Dental age of the most mesially located affected molar (DA) (years) Analyzed as first molar
Analyzed as second molar
1
F
UL
7.50
7.64Ⳳ0.96
5.1
9.0
2
F
UL
8.08
6.61Ⳳ0.78
5.1
9.0
3
F
UR
8.83
7.10Ⳳ0.73
5.1
9.0
4
F
UL/UR
6.58
5.83Ⳳ0.51
3.5
7.0
5
F
UL/UR/LL/LR
7.50
5.93Ⳳ0.42
3.5
7.0
*: The location of the affected molars are abbreviated as follows: UL: maxillary left; UR: maxillary right; LL: mandibular left; LR: mandibular right
Fig. 1 Orthopantomograph of Case 1 The maxillary left molar (arrow) was affected in this 7Y6M female.
Fig. 3 Orthopantomograph of Case 5 All four molars (arrows) were affected in this 7Y6M female.
ages (CA) ranged from 6.58 to 8.83 years. Single molars were affected in three cases, among which two were in the maxillary left region (Cases 1 and 2)
Fig. 2 Orthopantomograph of Case 4 Both the maxillary right and left molars (arrows) were affected in this 6Y7M female.
and the other was in the maxillary right region (Case 3). A representative orthopantomograph (Case 1) is presented in Fig. 1. In addition, two molars (both the maxillary right and left molars) were affected in Case 4 (Fig. 2) and all four molars were affected in Case 5 (Fig. 3). In each case, the dental age was calculated using the method described by Haavikko4), which have been proven to be valid for Japanese subjects3). The dental age of each tooth was assessed based on its developmental stage, after which the mean dental age was calculated by the dental age of the premolars and molars, excluding the affected molar region (MD). Subsequently, the dental age of the affected region (DA) was compared with MD. The CA was found to be more than 1 SD greater than MD in four cases. When the affected molars were considered to be first permanent molars, DA was approximately 1.51–2.43 years younger than MD,
186
Nishio, K., Nakano, K., Murakami, A. et al.
whereas DA was approximately 1.07–2.39 years older than MD when the affected molars were considered to be second permanent molars.
Discussion Several local and systemic conditions associated with delayed tooth eruption have been reported, and systematic classifications of delayed eruption have been recently proposed5,6). However, there is no known description of delayed eruption due to immature tooth formation, as in the present cases, though a previous report described similar cases, in which the affected molars were termed as “9-yearmolars”7). The pathological features of the patients with “9-year-molars” and those described in our study are somewhat similar. Rasmussen7) found that crossbite and severe hypodontia were present in some patients with “9-year-molars”; however, those features were not identified in our previous study3) or in the present report. The first permanent molars are known to emerge into the oral cavity and erupt at the age of 6 to 7 years, with their roots becoming complete by the age of 9 or 10 years2). The affected molars in the present patients had not emerged into the oral cavity by the age of 8 years 10 months due to immature tooth formation, which is estimated to delay eruption until the age of 9 to 10 years, as reported in our previous study3). The CA for Case 1 was not significantly different from the mean values of the dental ages calculated using the premolars and molars, excluding the affected molar region (MD). However, the MD for Cases 2, 3, 4, and 5 were significantly retarded as compared to their CA. Since the MD in most of our cases was delayed as compared to CA, we compared the MD and the dental age of the affected molars (DA). The DA ranged from 3.5 to 5.1 years old when the teeth considered to be first molars, indicating that the DA was approximately two years behind the MD, which is consistent with our previous report3). It is difficult to determine whether the phenomenon is due to the retarded development of a first permanent molar or the early eruption of a second permanent molar because of the congenital absent of the first molar. First permanent molars are considered to the most mesially located molar, which supports the speculation that the affected teeth in the present cases were first permanent molars. In spite of a few reports addressing the congenital absence of first molars, it is possible
to speculate that second molars mesially migrate towards the space of a congenitally missing first molar. The dental ages of the affected molars in the present cases were approximately two years older and approximately 1.5 years younger than the MD, when they were considered to be first and second molars, respectively. As a result, we propose that the present affected molars be newly categorized. The first molars are considered to be highly important for the mastication of food as well as in sustaining the vertical dimension of the face, because they are both the largest and strongest teeth, with well-developed cusps and roots, and provide maximum anchorage against force8). Therefore, children with delayed eruption of first molars are disadvantaged compared to children with normal eruption. However, it is reasonable to speculate that the reason for such delayed eruption is delayed tooth development and the best treatment modality is to wait for eruption while conducting periodic observations.
References 1) Winter, G.B.: Anomalies of tooth formation and eruption. In: Paediatric Dentistry. (Welbury, R.R. ed.) Oxford University Press, Oxford, 1997, pp.255–280. 2) Pinkham, J.R.: The dynamic of change. Physical changes. In: Pediatric Dentistry. 3rd ed. (Pinkham, J.R., Casamassimo, P.S., McTigue, D.J., Fields H.W. Jr. and Nowak, A.J. eds.) Elsevier Saunders, St. Louis, 1999, pp. 141–183. 3) Nakano, K., Matsuoka, T., Takahashi, A., Matsumura, M., Sobue, S. and Ooshima, T.: Delayed development or congenital absence of a single first permanent molar in Japanese child patients. Int J Paediatr Dent 9: 271–276, 1999. 4) Haavikko, K.: The formation and the alveolar and clinical eruption of the permanent teeth. An orthopantomographic study. Suom Hammaslaak Toim 66: 103–170, 1970. 5) Palma, C., Coehlho, A., Gozalez, Y. and Cahuana, A.: Failure of eruption of first and second permanent molars. J Clin Pediatr Dent 27: 239–246, 1999. 6) Suri, L., Gagari, E. and Vastardis, H.: Delayed tooth eruption: Pathogenesis, diagnosis, and treatment. A literature review. Am J Orthod Dentofacial Orthop 126: 432–445, 2004. 7) Rasmussen, P.: “9-year-molars” aberrantly developing and erupting: report of cases. J Clin Pediatr Dent 22: 151–153, 1998. 8) Woelfel, J.B.: Permanent maxillary molars. In: Permar’s Outline for Dental Anatomy. Lea & Febiger, Philadelphia, 1979, pp.87–99.
Case Report
Delayed eruption of first molars due to immature tooth formation: Report of five cases Kaori Nishio, Kazuhiko Nakano, Atsuko Murakami and Takashi Ooshima Department of Pediatric Dentistry, Osaka University Graduate School of Dentistry 1-8 Yamada-oka, Suita, Osaka 565-0871, JAPAN
Abstract Five cases of delayed eruption of the first molars due to immature tooth formation are presented. Three cases involved a teeth in a single quadrant, two of which were the maxillary left region while the other was in the maxillary right region. Both the maxillary left and right regions were affected in one case, and all four molar regions were affected in another case. Dental age was calculated by evaluating the tooth developmental stage in each case, and was compared with chronological age (CA). The mean dental age, excluding the affected molar region (MD), was compared with the dental age of the affected tooth (DA). The CA was more than 1 SD older than the MD in four cases. When we considered the affected molars to be first permanent molars, DA was 1.51– 2.43 years younger than MD in all five cases, while DA was approximately 1.07–2.39 years older than MD when the affected molars were considered as second permanent molars. These results indicated that the developmental stages of the affected molars were between that of the first and second molars, and were estimated to have emerged into oral cavity at an age between 9 and 10 years old.
Introduction Delayed eruption of first permanent molars is occasionally encountered, which is generally caused by ectopic eruption, impaction on the distal aspect of the primary second molars, or the presence of a physical barrier like an odontoma impeding the eruption pathway1). The tooth root is usually approximately one half to two thirds of its final length at the time of gingival emergence2) and delayed development of a tooth can be one of the causes for its delayed eruption. In our previous study, analysis of 353 orthopantomographs of child patients revealed nine cases of immature tooth formation of a single first molar, when the results were compared with the developmental status of all of the other first permanent molars3). The major characteristics of those cases were that the affected Received on January 6, 2006 Accepted on May 16, 2006
184
Key words Chronological age, Delayed eruption, Dental age, First molar, Second molar
teeth tended to erupt between the ages of 9 and 10 years, and showed an occlusal morphology similar to second molars rather than first molars. Furthermore, only one or two molars were identified in the affected quadrants of these patients, while the congenital absence of other permanent teeth were an additional complication in several of the cases. In the present study, we report five cases of retarded eruption of first molars due to immature tooth formation identified in our clinic in 2005. Three cases showed involvement of a single region and two had multiple quadrant involvement.
Case Reports Five patients with delayed eruption of the first molar were identified from orthopantomographic examinations conducted in the spring and summer of 2005 at the Pedodontics Clinic of Osaka University Dental Hospital. The Table 1 shows a summary of these five cases. All were females and their chronological
DELAYED ERUPTION OF M1 DUE TO IMMATURE TOOTH FORMATION
185
Table 1 Analysis of cases with retarded eruption due to immature tooth development Case no.
Gender
Affected molars*
Chronological age (CA) (years)
Mean dental age of premolar and molar region excluding affected tooth (MD) [MeanⳲSD (years)]
Dental age of the most mesially located affected molar (DA) (years) Analyzed as first molar
Analyzed as second molar
1
F
UL
7.50
7.64Ⳳ0.96
5.1
9.0
2
F
UL
8.08
6.61Ⳳ0.78
5.1
9.0
3
F
UR
8.83
7.10Ⳳ0.73
5.1
9.0
4
F
UL/UR
6.58
5.83Ⳳ0.51
3.5
7.0
5
F
UL/UR/LL/LR
7.50
5.93Ⳳ0.42
3.5
7.0
*: The location of the affected molars are abbreviated as follows: UL: maxillary left; UR: maxillary right; LL: mandibular left; LR: mandibular right
Fig. 1 Orthopantomograph of Case 1 The maxillary left molar (arrow) was affected in this 7Y6M female.
Fig. 3 Orthopantomograph of Case 5 All four molars (arrows) were affected in this 7Y6M female.
ages (CA) ranged from 6.58 to 8.83 years. Single molars were affected in three cases, among which two were in the maxillary left region (Cases 1 and 2)
Fig. 2 Orthopantomograph of Case 4 Both the maxillary right and left molars (arrows) were affected in this 6Y7M female.
and the other was in the maxillary right region (Case 3). A representative orthopantomograph (Case 1) is presented in Fig. 1. In addition, two molars (both the maxillary right and left molars) were affected in Case 4 (Fig. 2) and all four molars were affected in Case 5 (Fig. 3). In each case, the dental age was calculated using the method described by Haavikko4), which have been proven to be valid for Japanese subjects3). The dental age of each tooth was assessed based on its developmental stage, after which the mean dental age was calculated by the dental age of the premolars and molars, excluding the affected molar region (MD). Subsequently, the dental age of the affected region (DA) was compared with MD. The CA was found to be more than 1 SD greater than MD in four cases. When the affected molars were considered to be first permanent molars, DA was approximately 1.51–2.43 years younger than MD,
186
Nishio, K., Nakano, K., Murakami, A. et al.
whereas DA was approximately 1.07–2.39 years older than MD when the affected molars were considered to be second permanent molars.
Discussion Several local and systemic conditions associated with delayed tooth eruption have been reported, and systematic classifications of delayed eruption have been recently proposed5,6). However, there is no known description of delayed eruption due to immature tooth formation, as in the present cases, though a previous report described similar cases, in which the affected molars were termed as “9-yearmolars”7). The pathological features of the patients with “9-year-molars” and those described in our study are somewhat similar. Rasmussen7) found that crossbite and severe hypodontia were present in some patients with “9-year-molars”; however, those features were not identified in our previous study3) or in the present report. The first permanent molars are known to emerge into the oral cavity and erupt at the age of 6 to 7 years, with their roots becoming complete by the age of 9 or 10 years2). The affected molars in the present patients had not emerged into the oral cavity by the age of 8 years 10 months due to immature tooth formation, which is estimated to delay eruption until the age of 9 to 10 years, as reported in our previous study3). The CA for Case 1 was not significantly different from the mean values of the dental ages calculated using the premolars and molars, excluding the affected molar region (MD). However, the MD for Cases 2, 3, 4, and 5 were significantly retarded as compared to their CA. Since the MD in most of our cases was delayed as compared to CA, we compared the MD and the dental age of the affected molars (DA). The DA ranged from 3.5 to 5.1 years old when the teeth considered to be first molars, indicating that the DA was approximately two years behind the MD, which is consistent with our previous report3). It is difficult to determine whether the phenomenon is due to the retarded development of a first permanent molar or the early eruption of a second permanent molar because of the congenital absent of the first molar. First permanent molars are considered to the most mesially located molar, which supports the speculation that the affected teeth in the present cases were first permanent molars. In spite of a few reports addressing the congenital absence of first molars, it is possible
to speculate that second molars mesially migrate towards the space of a congenitally missing first molar. The dental ages of the affected molars in the present cases were approximately two years older and approximately 1.5 years younger than the MD, when they were considered to be first and second molars, respectively. As a result, we propose that the present affected molars be newly categorized. The first molars are considered to be highly important for the mastication of food as well as in sustaining the vertical dimension of the face, because they are both the largest and strongest teeth, with well-developed cusps and roots, and provide maximum anchorage against force8). Therefore, children with delayed eruption of first molars are disadvantaged compared to children with normal eruption. However, it is reasonable to speculate that the reason for such delayed eruption is delayed tooth development and the best treatment modality is to wait for eruption while conducting periodic observations.
References 1) Winter, G.B.: Anomalies of tooth formation and eruption. In: Paediatric Dentistry. (Welbury, R.R. ed.) Oxford University Press, Oxford, 1997, pp.255–280. 2) Pinkham, J.R.: The dynamic of change. Physical changes. In: Pediatric Dentistry. 3rd ed. (Pinkham, J.R., Casamassimo, P.S., McTigue, D.J., Fields H.W. Jr. and Nowak, A.J. eds.) Elsevier Saunders, St. Louis, 1999, pp. 141–183. 3) Nakano, K., Matsuoka, T., Takahashi, A., Matsumura, M., Sobue, S. and Ooshima, T.: Delayed development or congenital absence of a single first permanent molar in Japanese child patients. Int J Paediatr Dent 9: 271–276, 1999. 4) Haavikko, K.: The formation and the alveolar and clinical eruption of the permanent teeth. An orthopantomographic study. Suom Hammaslaak Toim 66: 103–170, 1970. 5) Palma, C., Coehlho, A., Gozalez, Y. and Cahuana, A.: Failure of eruption of first and second permanent molars. J Clin Pediatr Dent 27: 239–246, 1999. 6) Suri, L., Gagari, E. and Vastardis, H.: Delayed tooth eruption: Pathogenesis, diagnosis, and treatment. A literature review. Am J Orthod Dentofacial Orthop 126: 432–445, 2004. 7) Rasmussen, P.: “9-year-molars” aberrantly developing and erupting: report of cases. J Clin Pediatr Dent 22: 151–153, 1998. 8) Woelfel, J.B.: Permanent maxillary molars. In: Permar’s Outline for Dental Anatomy. Lea & Febiger, Philadelphia, 1979, pp.87–99.