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 Table of Contents  
CASE REPORT
Year : 2012  |  Volume : 3  |  Issue : 6  |  Page : 203-205  

Concomitant solitary median maxillary central incisor and fused right mandibular incisor in primary dentition


Department of Pedodontics and Preventive Dentistry, Narayana Dental College and Hospital, Nellore, Andhra Pradesh, India

Date of Web Publication18-Sep-2012

Correspondence Address:
Sivakumar Nuvvula
Department of Pedodontics and Preventive Dentistry, Narayana Dental College, Nellore, Andhra Pradesh- 524 003
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0976-237X.101094

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   Abstract 

Solitary median maxillary central incisor (SMMCI) is a unique developmental anomaly in primary dentition. It involves central incisor tooth germs and may or may not be associated with other anomalies. Its presence, concomitant with fusion of right mandibular incisors has not previously been reported. A 5-year-old girl was presented with a single symmetrical primary maxillary incisor at the midline, with the absence of labial frenulum, an indistinct philtrum and a prominent midpalatal ridge. There was an associated fused tooth in the right incisor region and radiographic examination confirmed only one maxillary central incisor in both the dentitions. Family history revealed that the father of the girl also had a similar anomaly providing probable evidence of etiological role for heredity in SMMCI.

Keywords: Central incisor, double tooth, maxillary, median, solitary median maxillary central incisor


How to cite this article:
Shilpa G, Nuvvula S, Gokhale N, Yamini V. Concomitant solitary median maxillary central incisor and fused right mandibular incisor in primary dentition. Contemp Clin Dent 2012;3, Suppl S2:203-5

How to cite this URL:
Shilpa G, Nuvvula S, Gokhale N, Yamini V. Concomitant solitary median maxillary central incisor and fused right mandibular incisor in primary dentition. Contemp Clin Dent [serial online] 2012 [cited 2019 Sep 17];3, Suppl S2:203-5. Available from: http://www.contempclindent.org/text.asp?2012/3/6/203/101094


   Introduction Top


Solitary median maxillary incisor (SMMCI) is a rare anomaly with a reported prevalence of 1 in 50,000 live births and is more common among females. [1] The most common clinical presentation in the oral cavity is the presence of a single central incisor at the midline of the maxilla in both dentitions. The etiology of SMMCI is unknown, but it may be related to a disruption in the development of the maxilla, which occurs at approximately 35-38 days of intrauterine life, with abnormal formation of tooth germs and alveolar bone or soft tissue. [2],[3],[4] It is known to be associated with anomalies of midline structures of brain and face, growth retardation (with or without growth hormone deficiency), malformations of sella, choanal atresia, mid-nasal stenosis, and pyriform aperture stenosis. [1],[5],[6] The anomaly occurs due to disruption in development of maxilla leading to lack of space and premature fusion of dental lamina. [3],[4] Cases of isolated SMMCI without any associated anomalies have also been reported. [7] It could also form part of a syndrome well known as Solitary median maxillary incisor syndrome (SMMCIS) which includes symmetrical central incisor, absence of labial frenulum and incisive papilla, absence of inter-maxillary suture in front of the incisive fossa, and a prominent mid-palatal ridge. [8] It may be associated with holoprocencephaly, [9],[10] Goldenhar's syndrome, [11] and oromandibular-limb hypogenesis syndrome type 1. [12] We report a case of SMMCI in a 5-year-old girl concomitant with fusion of right mandibular incisors.


   Case Report Top


A 5-year-old girl, only child, born to nonconsanguineous parents was brought to our out patient clinic with complaint of a large anterior tooth in the maxillary arch. On clinical examination the child was of normal built (weight: 20 kg, height: 112 cm, and head circumference: 49 cm). The philtrum was indistinct. Intraoral examination revealed an absent maxillary median labial frenulum with a large, symmetrical, midline tooth, and fused right mandibular incisors [Figure 1]. The incisive fossa was prominent along with a very prominent midpalatal ridge [Figure 2]. The intraoral periapical radiograph revealed only one central incisor with single root and root canal and no impacted tooth but with only one developing succedaneous tooth [Figure 3]a. Intraoral periapical radiograph of mandibular incisors confirmed fusion of right primary central and lateral incisors [Figure 3]b. Family history revealed that her father also had a similar anomaly with midline single maxillary incisor.
Figure 1: Clinical picture showing large median maxillary incisor with absent labial frenulum and fused mandibular right incisor

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Figure 2: Intraoral picture shows prominent midline palatal ridge

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Figure 3: Intraoral periapical radiographs revealing solitary central incisor with one root and root canal and one
succedaneous tooth (a), and fused mandibular right primary incisors (b)


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   Discussion Top


The prevalence of double tooth in various studies ranges from 0.1% to 4.1%. The prevalence rate shows a definite geographical variation, the Chinese and Japanese having high prevalence rates. [13] It is more common in the anterior mandibular region of primary dentition. Most frequent combination in double tooth includes central and lateral incisor or lateral incisor and canine. Double tooth involving maxillary central incisors in primary dentition is very rare. It can present as a solitary finding SMMCI, solitary median maxillary central incisor syndrome (SMMCIS) or it can be a mild manifestation along with multisystemic major anomalies. Traumatic loss, fusion of primary or permanent central incisors with a supernumerary tooth and mesiodens must be ruled out before diagnosing SMMCI. In conditions where two maxillary central incisors began normal development but failed to proceed beyond the cellular developmental stage cannot be diagnosed as SMMCI. [7] The case presented by us showed double tooth (fusion) in the mandibular right incisor region.

Hitchin and Morris [14] have shown that persistence of interdental lamina (which maintains continuity between tooth germs) initiates formation of double tooth. Several cases of double teeth in families have been reported implicating a hereditary cause. Various etiological factors have been implicated for SMMCI. Disruption of maxilla during intrauterine period of 35-38 days may lead to lack of space and premature fusion of dental lamina across the midline resulting in SMMCI. [5],[6] Solitary median incisor is seen in all patients with holoprosencephaly which is a midline developmental defect of prosencephalon and face. [10] Mutations in human sonic hedgehog gene can cause holoprosencephaly. [15] It has an autosomal dominant inheritance with 70% penetrance. [16] Solitary median incisor could also be associated with CHARGE (coloboma, heart defects, choanal atresia, retarded growth and development, genital anomalies, and ear anomaly), VACTERL (vertebral anomalies, cardiac anomalies, trachea-oesophageal fistula, nasal and labial anomalies), Goldenhar's syndrome, hypothalamic hamartoma, triple-X syndrome, ectodermal dysplasia, hypotelorism, and mid-axial defects of craniofacial and brain structures. [6],[7],[11]

Children with SMMCIS could have growth and mental retardation. There are cases of SMMCIS with short stature and growth hormone deficiency. However, Cho and Drummond in their report of three cases of SMMCIS have reported normal growth. [17] Stanhope et al, [18] felt that growth abnormalities could manifest at a later stage. Hall et al. [1] suggest regular follow up of SMMCIS children associated with at least 2 SD below the mean height for their age and gender by an endocrinologist. They have demonstrated abnormal sella turcica in their cases. Pituitary function and sellar structure may or may not be associated; in the case reported by Bolan et al., sella turcica was normal. [2] Though the SMMCIS is shown to be associated with learning difficulty there have been various reports with normal intellectual development. [2],[4]

SMMCIS is sometimes associated with midline nasal cavity abnormalities like choanal atresia, nasal stenosis, and aperture stenosis. These children may or may not manifest obstruction symptoms. In the case reported by Velasco et al. there was severe asphyxia at birth. [19] Hall et al. and Kjaer et al. [1],[10] have found that clinically symptomatic obstruction is present in only few of their patients with neonatal nasal obstruction. Hall et al.[1] recommend evaluation by an otolaryngologist once a diagnosis of SMMCIS is made. Bolan et al.[2] have reported "open trachea" causing breathing difficulty in their case.

Chromosomal deletions have been shown in chromosomes no. 7, 18 and 22 in some cases of SMMCIS. [1],[15] In the two cases of SMMCIS reported by Yassin and Bolan [2],[20] in one of the twins, the other twin was normal. In the online database developed by John Hopkins University this SMMCIS is referred as Online Mendelian Inheritence in Man [21] (OMIM 147250). Our report involving the child patient and her father with manifestation in both of them supports possible X-linked dominant inheritance apart from autosomal inheritance pattern, though this needs further proof of genetic analysis for which the family did not give consent.

SMMCIS can be associated with posterior cross bite, [1],[4],[22] Beckor et al, [23] have dislocated the mandible on the right side because of occlusion repositioning provoked by contact with a canine tooth. Some authors recommend treatment with orthodontic appliances at the permanent dentition stage to gain space for implant-prosthodontic rehabilitation. [6],[7],[24]

Johnson et al. [25] used magnetic resonance imaging (MRI) for prenatal diagnosis of solitary median maxillary central incisor syndrome and reported that MRI provided detailed insight into fetal anatomy and pathology, aiding prenatal diagnosis, and facilitating parental counseling.


   Conclusion Top


SMMCIs should alert the clinician towards possible associations. These children require evaluation by endocrinologist and otolaryngologist. Genetic studies are required to establish the possible mutations. Parents should be counseled regarding the need for regular follow up by the multidisciplinary team.

 
   References Top

1.Hall RK, Bankier A, Aldred MJ, Kan K, Lucas JO, Perks GB. Solitary median maxillary central incisor, short stature, choanal atresia/midnasal stenosis (SMM-CI) syndrome. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1997;84:651-62.  Back to cited text no. 1
    
2.Bolan M, Derech CD, Ribeiro GL, Pereira ET, Almeida IC. Solitary median maxillary central incisor. J Dent Child (Chic) 2009;76:82-6.  Back to cited text no. 2
[PUBMED]    
3.DiBiase AT, Elcock C, Smith RN, Brook AH. A new technique for symmetry determination in tooth morphology using image analysis: Application in the diagnosis of solitary maxillary median central incisor. Arch Oral Biol 2006;51:870-5. Epub 2006 Apr 18.  Back to cited text no. 3
    
4.Harrison M, Calvert ML, Longhurst P. Solitary maxillary central incisor as a new finding in CHARGE association: A report of two cases. Int J Paediatr Dent 1997;7:185-9.  Back to cited text no. 4
[PUBMED]    
5.Rappaport EB, Ulstrom RA, Gorlim RJ. Monosupero-centroincisivodontic dwarfism. Birth Defects Orig Artic Ser 1976;12:243-5.  Back to cited text no. 5
    
6.Lo FS, Lee YJ, Lin SP, Shen EY, Huang JK, Lee KS. Solitary maxillary central incisor and congenital nasal pyriform aperture stenosis. Eur J Pediatr 1998;157:39-44.  Back to cited text no. 6
[PUBMED]    
7.Hall RK. Solitary median maxillary central incisor (SMMCIS) syndrome. Orphanet J Rare Dis 2006;1:12.  Back to cited text no. 7
[PUBMED]    
8.Bazan MT. Fusion of maxillary incisor across the midline: Clinical report. Pediatr Dent 1983;5:220-1.  Back to cited text no. 8
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9.Viana Eda S, Kramer PF, Closs LQ, Scalco G. Solitary median maxillary central incisor syndrome and holoprosencephaly: A case Report. Pediatr Dent 2010;32:424-7.  Back to cited text no. 9
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10.Kjaer I, Becktor KB, Lisson J, Gormsen C, Russel BG. Face, palate, and craniofacial morphology in patients with a solitary median maxillary central incisor. Eur J Orthod 2001;23:63-73.  Back to cited text no. 10
    
11.Garcia de Paula e Silva FW, de Carvalho FK, Diaz-Serrano KV, de Freitas AC, Borsatto MC, de Queiroz AM. Solitary median maxillary central incisor in association with Goldenhar's syndrome: A case report. Spec Care Dentist 2007;27:104-7.  Back to cited text no. 11
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12.Lertsirivorakul J, Hall RK. Solitary median maxillary central incisor syndrome occurring together with oromandibular-limb hypogenesis syndrome type 1: A case report of this previously unreported combination of syndromes. Int J Paediatr Dent 2008;18:306-11. Epub 2008 Mar 6.   Back to cited text no. 12
    
13. Yonezu T, Hayashi Y, Sasaki J, Machida Y. Prevalence of congenital dental anomalies of the deciduous dentition in Japanese children. Bull Tokyo Dent Coll 1997;38:27-32.  Back to cited text no. 13
    
14.Hitchin AD, Morris I. Geminated odontome-connation of the incisors in the dog- its etiology and ontogeny. J Dent Res 1966;45:575-83.  Back to cited text no. 14
    
15.Hehr U, Gross C, Diebold U, Wahl D, Beudt U, Heidemann P, et al., Wide phenotypic variability in families with holoprosencephaly and a sonic hedgehog mutation. Eur J Pediatr 2004;163:347-52. Epub 2004 Apr 24.  Back to cited text no. 15
    
16.Cohen MM Jr. An update on the holoprosencephalic disorders. J Pediatr 1982; 101:865-9.  Back to cited text no. 16
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17.Cho SY, Drummond BK. Solitary median maxillary central incisor and normal stature: A report of three cases. Int J Pediatr Dent 2006;16:128-34.  Back to cited text no. 17
    
18.Stabnhope R, Preece MA, Brook CG. Hypoplastic optic nerves and pituitary dysfunction A spectrum of anatomical and endocrine abnormalities. Arch Dis Child 1984;59:111-4.  Back to cited text no. 18
    
19.Velasco DMM, Ramírez JAF, Nagano AY. Incisor syndrome Single central midline fusion of the maxillary and mandibular permanent central incisors: Report of clinical case. Rev Odont Mex 2005;9:37-41. (Velasco DMM, Ramírez JAF, Nagano AY. Síndrome del incisivo central único de la línea media del maxilary fusión de incisivos centrales permanentes mandibulares:Reporte de um caso clínico. Rev Odont Mex 2005;9:37-41.)  Back to cited text no. 19
    
20.Yassin OM, El-Tal YM. Solitary maxillary central incisor in the midline associated with systemic disorders. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1998;85:548-51.  Back to cited text no. 20
    
21.Online Mendelian Inheritence in Man, OMIM (TM). McKusick-Nathans Institute for Genetic Medicine, John Hopkins University (Baltimore, MD) and National Center for Biotechnology Information, National Library of Medicine (Bethesda, MD), 2000 http://www.ncbi.nlm.nih.gov/omim/.  Back to cited text no. 21
    
22.Lowry RB. Letter: Holoprosencephaly. Am J Dis Child 1974;128:887.  Back to cited text no. 22
    
23.Becktor KB, Sverrild L, Pallisgaard C, Burhoj J, Kjaer I. Eruption of the central incisor, the intermaxillary suture, and maxillary growth in patients with a median maxillary central incisor. Acta Odontol Scand 2001;59:361-6.  Back to cited text no. 23
    
24.Wesley RK, Hoffman WH, Perrin J, Delaney JR jr. Solitary maxillary central incisor and normal stature. Oral Surg Oral Med Oral Pathol1978; 46:837-42.  Back to cited text no. 24
    
25.Johnson N, Windrim R, Chong K, Viero S, Thompson M, Blaser S. Prenatal diagnosis of solitary median maxillary central incisor syndrome by magnetic resonance imaging. Ultrasound Obstet Gynecol 2008;32:120-2.  Back to cited text no. 25
    


    Figures

  [Figure 1], [Figure 2], [Figure 3]



 

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