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 Table of Contents  
CASE REPORT
Year : 2021  |  Volume : 13  |  Issue : 2  |  Page : 121-124

Solitary median maxillary central incisor: Gateway to diagnosis of systemic diseases


1 Department of Prosthodontics, 3 Corps Dental Unit, Kochi, Kerala, India
2 Department of Peadodontics, INHS Sanjivani, Kochi, Kerala, India
3 Department of Orthodontics, Army Dental Centre (Research & Referral), New Delhi, India
4 Dental Officer (Pedodontics), Fd Hosp, Manipur, India, India

Date of Submission08-Oct-2020
Date of Acceptance06-Feb-2021
Date of Web Publication22-Jun-2021

Correspondence Address:
Rahul Kaul
House No. 150, MH Road, EktaVihar, Udhampur - 182 101, Jammu and Kashmir
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jorr.jorr_49_20

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  Abstract 


A Solitary median maxillary central incisor (SMMCI) is a rare dental anomaly that may occur alone or be associated with other systemic conditions. Most common association is with holoprosencephaly. It can easily be misdiagnosed as a simple case of hypodontia due to either traumatic dental injury or fusion of two central incisors or a mesiodens developing to the one side of midline or any other condition that may lead to growth termination of central incisor at the cellular level. Every dentist needs to be aware of oral manifestations of this anomaly, thereby facilitating an early diagnosis of SMMCI, as it may be a sign of other severe congenital or developmental anomalies. Proper follow-up and close monitoring of the growth and development of SMMCI patients are of critical importance. The aim of this paper was to report a case of a 12-year-old female child with an SMMCI and describe important symptoms of this syndrome.

Keywords: Congenital, incisor, single, solitary, systemic diseases


How to cite this article:
Talwar BS, Dempsy Chengappa M M, Bali A, Kaul R. Solitary median maxillary central incisor: Gateway to diagnosis of systemic diseases. J Oral Res Rev 2021;13:121-4

How to cite this URL:
Talwar BS, Dempsy Chengappa M M, Bali A, Kaul R. Solitary median maxillary central incisor: Gateway to diagnosis of systemic diseases. J Oral Res Rev [serial online] 2021 [cited 2021 Dec 5];13:121-4. Available from: https://www.jorr.org/text.asp?2021/13/2/121/319025




  Introduction Top


Solitary median maxillary central incisor syndrome (SMMCIS) is a rare dental anomaly (OMIM 147250) that mainly presents as an esthetic concern to a dentist. SMMCIS was initially described by Hall et al. in 1997.[1] As per literature, the estimated incidence of SMMCIS is reported to be 1 in 50,000 live births. Higher incidence is reported in aborted fetuses and still births.[2] Solitary median maxillary central incisor can either be an isolated dental finding or as a part of SMMCIS; a complex neurodevelopmental disorder affecting midline structures of the head occurring as a result of unknown events occurring between 35th and 38th days of intrauterine life. SMMCIS is known to involve cranial bones, especially maxilla and its dentition, nasal airways, and brain along with other midline structures of the body.[3]

The most noteworthy feature of SMMCIS is the presence of a single maxillary central incisor in both primary and permanent dentitions located exactly in the midline region.[4] Timely detection and diagnosis of this syndrome are important because it may lead to diagnosis of more severe congenital malformations. Treatment approach is always multidisciplinary.


  Case Report Top


A 12-year-old female child reported to our department of dentistry with chief complaint of single large upper front tooth that led to low self-esteem and communion among her peers. The child's parents had a consanguineous marriage. Neither her parents nor any of her siblings were affected by SMMCIS. Medical history revealed that the child was born through a cesarean section as a full-term baby and had normal birth weight. Dental history revealed that she had only one deciduous maxillary central incisor. No other relevant medical history was observed.

On clinical examination, the child had a mesoprosopic facial form. On extraoral examination, no facial asymmetry was observed [Figure 1]. She had a complete set of permanent dentition erupted excluding all four third molars. Maxillary and mandibular arches were found to be symmetrical to each other. Angles' Class 1 molar relationship with mild crowding in both maxillary and mandibular dentition was observed. Only one maxillary central incisor was present that too in the midline. Philtrum of the upper lip could not be appreciated, and incisive papilla was missing as well. In addition to this, both maxillary and mandibular labial frena were absent [Figure 2]. A good oral hygiene was maintained by the child. Radiographic examination ruled out the presence of any mesiodens, unerupted tooth, or impacted tooth [Figure 3] and [Figure 4]. There was no history of dental trauma to primary as well as permanent dentition. Treatment plan was explained to the child's parents. The child was referred to a pediatrician to rule out possibility of any systemic disease and obtain consent to carry out dental treatment. No systemic finding was observed by pediatrician. The child was then referred to the department of orthodontics to reposition the tooth to a desired position and create space for implant or fixed dental prosthesis in the future.
Figure 1: Extraoral photograph

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Figure 2: Intraoral photograph

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Figure 3: Orthopantomogram of the patient

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Figure 4: IOPA of the single median maxillary central incisor

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  Discussion Top


Solitary median maxillary central incisor (SMMCI) is a rare developmental anomaly that may occur sometimes as an isolated dental finding.[5] Presence of SMMCI can lead to the diagnosis of various associated anomalies such as holoprosencephaly (HPE), choanal atresia, nasal pyriform aperture stenosis, and greater risk of pituitary malformation.[6]

Although the etiology is largely unknown, it has been hypothesized that missense mutation in Sonic Hedgehog gene at 7q36.1 may be lead to the formation of SMMCI.[7],[8] Hall et al. proposed that a critical absence of or reduction in the lateral growth from the midline, on or around 35th or 38th day of gestation, leads to premature fusion of the epithelial dental lamina, thereby preventing the formation of two complete central incisors, hence leading to the formation of SMMCI.[1] Uniqueness of single central incisor is attributed to its morphology with identical right and left surfaces, unlike a normal central incisor. Maxillary and mandibular buccal frena are missing in these cases. The present case displayed all these features.[2]

Early diagnosis of cases of SMMCI is important as it could be a manifestation of other more severe developmental and congenital anomalies.[9] This can be done prenatally with ultrasound or genetic testing. Diagnosis can be made at birth and even prenatally at 18–22 weeks by ultrasound or genetic testing. Evaluation of dental alveoli and germinal teeth by prenatal ultrasound in fetuses with midline pathology facilitates diagnosis of SMMCI and associated anomalies.[6]

Various other congenital anomalies frequently found in association with SMMCI are severe-to-mild intellectual disability, congenital heart disease, cleft lip and/or palate and less frequently, hypotelorism, hypothyroidism, hypopituitarism, microcephaly, absent kidney, convergent strabismus, esophageal and duodenal atresia, cervical hemivertebrae, cervical dermoid, scoliosis, micropenis, and ambiguous genitalia.[10],[11]

SMMCIS requires comprehensive treatment by a team comprised pediatric neonatologist, obstetrician, pediatric otolaryngologist, geneticist, pediatric neurologist, pediatric endocrinologist, pediatric dentist, orthodontist, and prosthodontist.[5]

Pediatric neonatologist and obstetrician play a role in diagnosis of respiratory distress due to congenital nasal obstruction if present at birth and refer the child immediately to an otolaryngologist. Geneticist will be helpful in the detection of this syndrome by the assessment of family pedigree and genetic analysis. Early referral to the pediatric dentist proves helpful in monitoring growth of the child. Patients' facial growth pattern in both transverse and sagittal directions should be analyzed right from primary dentition stage. Treatment is not done at the primary dentition stage. Pediatric neurologist should be consulted in case of HPE. Growth abnormalities such as deficiency of growth hormone that leads to short stature are taken care by the pediatric endocrinologist. In the permanent dentition, treatment regimen includes orthodontic intervention in the form of either palatal expansion, distalization of the first permanent molars, or otherwise, extraction of premolars to create space for replacement of the contralateral missing central incisor.[12] After creating space for contralateral artificial central incisor, the prosthodontist places a single tooth implant or fixed partial denture at appropriate age.

Solitary median maxillary central incisor easily misses diagnosis. Cases in primary dentition have been reported.[9],[12],[13],[14] Differential diganosis includes hypodontia due to either traumatic dental injury or fusion of two central incisors or a mesiodens developing to the one side of midline or any other condition that may have led to growth termination of central incisor at the cellular level. Every dentist needs to be aware of oral manifestations of this anomaly, thereby facilitating an early diagnosis of SMMCI, as it may be a sign of other severe congenital or developmental anomalies. Proper follow-up and close monitoring of the growth and development of SMMCI patients is of critical importance.


  Conclusion Top


SMMCI is a rare condition which may point toward other severe congenital and developmental anomalies. A multidisciplinary approach is key to successful early diagnosis and management of this condition. A suitable treatment plan tailor made based on the various associated anomalies over different phases of the life of the patient would be critical in successful long-term care.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

Ethical clearance

DS3/2020/03 dt 07 Aug 2020.



 
  References Top

1.
Hall RK, Bankier A, Aldred MJ, Kan K, Lucas JO, Perks AG. Solitary median maxillary central incisor, short stature, choanal atresia/midnasal stenosis (SMMCI) syndrome. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1997;84:651-62.  Back to cited text no. 1
    
2.
Hall RK. Solitary median maxillary central incisor (SMMCI) syndrome. Orphanet J Rare Dis 2006;1:12.  Back to cited text no. 2
    
3.
El-Jaick KB, Fonseca RF, Moreira MA, Ribeiro MG, Bolognese AM, Dias SO, et al. Single median maxillary central incisor: New data and mutation review. Birth Defects Res A Clin Mol Teratol 2007;79:573-80.  Back to cited text no. 3
    
4.
Youko K, Satoshi F, Kubota K, Goto G. Clinical evaluation of a patient with single maxillary central incisor. J Clin Pediatr Dent 2002;26:181-6.  Back to cited text no. 4
    
5.
Scott DC. Absence of upper central incisor. Br Dent J 1958;104:247-8.  Back to cited text no. 5
    
6.
Faure JM, Captier G, Bäumler M, Boulot P. Sonographic assessment of normal fetal palate using three-dimensional imaging: A new technique. Ultrasound Obstet Gynecol 2007;29:159-65.  Back to cited text no. 6
    
7.
Nanni L, Ming JE, Du Y, Hall RK, Aldred M, Bankier A, et al. SHH mutation is associated with solitary median maxillary central incisor: A study of 13 patients and review of the literature. Am J Med Genet 2001;102:1-10.  Back to cited text no. 7
    
8.
Dolan LM, Willson K, Wilson WG. 18p-Syndrome with a single central maxillary incisor. J Med Genet 1981;18:396-8.  Back to cited text no. 8
    
9.
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:S203-5.  Back to cited text no. 9
    
10.
Mustafa MM, Zakirulla M, AlShahrani I, Togoo RA, Alkahtani ZM, Ain TS. Clinical evaluation of solitary median maxillary central incisor syndrome. Case Rep Dent 2019;2019:2637825.  Back to cited text no. 10
    
11.
Garcia Rodriguez R, Garcia Cruz L, Novoa Medina Y, Garcia Delgado R, Perez Gonzalez J, Palma Milla C, et al. The solitary median maxillary central incisor (SMMCI) syndrome: Associations, prenatal diagnosis, and outcomes. Prenat Diagn 2019;39:415-9.  Back to cited text no. 11
    
12.
Bolan M, Derech CD, Côrrea M, Ribeiro GL, Almeida IC. Palatal expansion in a patient with solitary median maxillary central incisor syndrome. Am J Orthod Dentofacial Orthop 2010;138:493-7.  Back to cited text no. 12
    
13.
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. 13
    
14.
Lygidakis NN, Chatzidimitriou K, Petrou N, Lygidakis NA. Solitary median maxillary central incisor syndrome (SMMCI) with congenital nasal puriform aperture stenosis: Literature review and case report with comprehensive dental treatment and 14 years follow-up. Eur Arch Paediatr Dent 2013;14:417-23.  Back to cited text no. 14
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4]



 

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