A maxillary midline supernumerary tooth is the most common type of supernumerary tooth. We present a case of a mesiodens, preventing eruption of a permanent central incisor. The aetiology, diagnosis and the effect of these developmental anomalies upon the dentition are discussed.peer-reviewe

Azzopardi, Alexander

Camilleri, Simon

DePasquale, Sandra

English

OAR@UM

Malta Medical Journal    Volume 17   Issue 02   July 2005 37Mesiodens Preventing Eruptionof a Permanent Central IncisorCase ReportSandra DePasquale,  Alexander Azzopardi, Simon CamilleriKeywordsTooth, supernumerary; tooth, unerupted;  mesiodensSandra DePasquale BChD Vth yearDepartment of Dental Surgery,St. Luke’s Hospital, Gwardamangia, Malta.Email: sandydep@di-ve.comAlexander Azzopardi BChD PhDDepartment of Dental Surgery,St. Luke’s Hospital, Gwardamangia, Malta.Email: aazz2@um.edu.mtSimon Camilleri MSc MOrth RCSFaculty of Dental Surgery,University of Malta Medical and Dental School,Gwardamangia, Malta.Email: xmun@onvol.netAbstractA maxillary midline supernumerary tooth is the mostcommon type of supernumerary tooth. We present a case of amesiodens, preventing eruption of a permanent central incisor.The aetiology, diagnosis and the effect of these developmentalanomalies upon the dentition are discussed.IntroductionHyperdontia (supernumerary teeth) is a developmentalanomaly in which extra teeth are formed.1,2 Supernumerary teethare classified as:a) Accessory, where the morphology is different to that of thenormal series.b) Supplemental teeth, with morphology similar to normalteeth.Accessory teeth can also be subclassified into:i) Conical (peg-shaped)ii) Tuberculate (barrel-shaped)iii) OdontomeThe prevalence of supernumerary teeth ranges from 0.15%to 3.9% 3 and are five times more common in the maxilla, witha male to female ratio of 2:1.4 Supernumerary teeth are lesscommon in the deciduous dentition, with an incidence of 0.3%to 1.7%.5 A supernumerary deciduous tooth is followed by asupernumerary permanent tooth in 35% - 50% of cases. Themajority of supernumerary teeth remain unerupted.  It has beenstated that only 25% of anterior supernumerary teeth eruptspontaneously.6Multiple supernumerary teeth may be a feature of asyndrome, such as; cleidocranial dysostosis, Gardner’ssyndrome, cleft lip and palate, Fabry-Anderson’s Syndrome orchondroectodermal dysplasia (Ellis-van Greveld Syndrome).2,7A mesiodens is an accessory supernumerary tooth presentin the midline of the maxilla between the two incisors.  It is themost frequent supernumerary tooth with an overall prevalenceof 0.15% to 1.9%.8 It may occur individually or as multiples(mesiodentes).  A mesiodens that is palatally located is the mostcommon type, and is usually unerupted.  This type ofsupernumerary tooth often prevents the maxillary incisors fromcontacting each other, resulting in the formation of a mid-linediastema.Case ReportA healthy 9 year old boy was referred by his General DentalPractitioner to the School Dental Clinic (SDC) Floriana, becauseof delayed eruption (>2 years) of the permanent upper leftFigure 1: Standard Maxillary Occlusal view of the premaxilla,showing an unerupted, inverted mesiodens (arrowed). 21 ismagnified and indistinct, indicating it’s position as beingbuccal to the arch.38 Malta Medical Journal    Volume 17   Issue 02   July 2005central incisor (21).  A Standard Maxillary Occlusal radiograph(SMO) was taken (Figure 1).  The radiograph revealed amesiodens and an unerupted 21.  A periapical radiograph ofthe upper left incisor region was taken to reveal further detailof the area and for localization of the mesiodens using theparallax radiographic principle (Figure 2).  This showed themesiodens to be located palatal to the central incisor.The patient was subsequently referred to the Oral SurgeryDepartment at St. Luke’s Hospital for the removal of themesiodens and exposure of the 21.Treatment was carried out as a day case using generalanesthesia.  61 and 62 were extracted.  A gingival sulcularincision in the gingival sulcus, extending from the upper leftdeciduous canine to the upper deciduous right canine, wasperformed to raise a full thickness palatal envelope flap.  Bonewas removed to uncover the supernumerary tooth with a roundbur, allowing the tooth to be elevated and removed from itsposition.Bone overlying the 21 was removed with a round bur tofacilitate it’s eruption and the flap closed over the crown of theexposed tooth with four black silk sutures.On discharge the patient was prescribed Amoxicillin 250mgcaps tds for five days.At one week recall for removal of sutures, healing wasuneventful.At the three month review it was found that unexpectedmesial drift of the permanent upper left lateral incisor (22), intothe space of the unerupted 21, had taken place. Both upperdeciduous canines were extracted under local anaesthetic toallow retraction of the 22 with an upper removable appliance,in order to provide space for the 21 to erupt spontaneously. One year post-operatively the 21 had erupted, albeit slightlyproclined.  A second appliance was used to realign the 21 intoplace.The position of the tooth is now satisfactory (Figure 3).DiscussionThe aetiology of supernumerary teeth remains unknown;however, it is appropriate to consider hyperdontia as amultifactorial inheritance disorder.9  Whist the occurrence ofsupernumerary teeth cannot be predicted, the influence ofgenetic factors is strongly suggested.5  Familial occurrence ofmesiodens has been reported to involve siblings and sequentialgenerations of a single family, and is thus thought to be anautosomal dominant condition with incomplete penetrance.  Asexlinked pattern of inheritance may also be acting.3 Several theories have been put forward concerning thecause of this dental anomaly; the most widely accepted of theseis the hyperactivity theory, which implies that supernumeraryteeth are the result of excessive but organized growth of thedental lamina.  Remnants of the dental lamina or palatalextensions of the active dental lamina are induced to developinto an additional tooth bud, which results in a supernumerarytooth.7Mesiodentes can cause impaction or ectopic eruption of themaxillary incisors.  To this end, in a recent reprospective studyon 47 Maltese cases, Betts and Camilleri10 reported thatsupernumerary teeth were the most common cause of failure oferuption of maxillary incisors, having put the figure at 47%.Figure 2: Intraoral periapical view taken with a distal tubeshift for localization using horizontal parallax. The mesiodens(arrowed) has moved distal relative to the root of the deciduouscentral incisor and the crown of the buried permanent incisor,indicating it’s position as palatal to the line of the arch.Figure 3: Intraoral view showing tooth 21 in place after beingretracted with an orthodontic appliance.Malta Medical Journal    Volume 17   Issue 02   July 2005 39They also reported that, following the removal of thesupernumerary teeth and conventional surgery andorthodontics, the maxillary incisors usually erupt successfully.It is therefore important that clinical diagnosis and managementof this condition occurs early, in order to minimize aestheticand occlusal problems which may arise.3Diagnosis: This is by radiography, either as an incidentalfinding, or following investigation of an occlusal anomaly.Careful localization of the supernumerary tooth, utilizingradiographic techniques, such as parallax, is indicated prior tosurgery and is normally carried out using supplementaryintraoral views.The Dental Panoramic Tomogram (DPT) is unreliable in thistype of case as the focal trough is very narrow in the anteriorregion.  Part of the premaxilla may lie outside the trough andmay not be visualized.  This view may be used to supplementintraoral views if pathology in other parts of the jaws issuspected.Supernumerary teeth may affect the dentition in variousways.  Some of the problems these teeth can cause are:1. crowding2. displacement and/or rotation3. failure of eruption4. hindrance of orthodontic movement5. enlargement of the follicle and possible cystic changeIn all these cases the treatment of choice is extraction of thesupernumerary tooth, with orthodontic treatment asappropriate.If the unerupted supernumeraries exhibit no pathology andwill not interfere with orthodontic movement of the adjacentteeth, they are usually left in situ. Periodic radiographic controlis essential, as degeneration of the follicle may lead todevelopment of a dentigerous cyst.When surgical removal of a supernumerary tooth isindicated, this is best carried out under general anesthesia.11  Itis important to ensure that enough space for the unerupted toothto erupt into is present. Lack of space may necessitate extractionof other teeth with or without orthodontic intervention.  Onceenough space is present, the tooth should erupt after 12 months,in a pre-pubertal patient.  However, if it remains unerupted aftertwo years, re-exposure and orthodontic traction is indicated.11,13Post-pubertal patients should have an attachment and chainbonded at the time of exposure and traction appliedstraightaway.During surgery, care must be taken not to damage theadjacent developing teeth or follicles.12ConclusionEarly detection and management of all supernumerary teethis a necessary part of preventive dentistry.  In this wayorthodontic problems and/or dental pathology associated withhis dental anomaly can be avoided. 12  The importance of earlyradiographic investigation of suspect cases cannot beunderstated.References1. Cawson R A, Odell E W, Cawson’s Essentials of Oral Medicineand Pathology, 7th edn, Churchill Livingstone, 2002;19-20.2. Soames J V, Southam J C, Oral Pathology, 3rd edn, OxfordUniversity Press, 1998.3. Russell K A, Folwarczna M A, Mesiodens – Diagnosis andmanagement of a common supernumerary tooth, Journal of theCanadian Dental Association, 2003; 69: 362-366.4. Stellzig A, Basdra E K, Komposch G, Mesiodentes: incidence,morphology, etiology, Journal of Orofacial Orthopedics, 1997; 58(3): 144-153.5. Scheiner M A, Sampson W J, Supernumerary teeth: A review ofthe literature and four case reports, Australian Dental Journal,1997; 42:3, 160-165.6. Tay F, Pang A, Yuen S, Unerupted maxillary anterior supernu-merary teeth: report of 204 cases, Journal of Dentistry forChildren, 1984; 51: 284-294.7. Gallas M M, Garcia A, Retention of permanent incisors bymesiodens: a family affair, British Dental Journal, 2000; 188: 63-64.8. Sedano H O, Gorlin R J, Familial occurrence of mesiodens, OralSurgery Oral Medicine Oral Pathology, 1969; 27 (3): 360-361.9. Weber F, Supernumerary teeth, Dental Clinics of NorthernAmerica, 1964:509-517.10. Betts A, Camilleri G E, A review of 47 cases of uneruptedmaxillary incisors, International Journal of Paediatric Dentistry,1999; 9: 285-292.11. Sharma A, Familial occurrence of mesiodens – a case report,Journal of Indian Society of Pedodontics and PreventiveDentistry, 2003; 21; 84-85.12. Saeed N R, Mackay F A, The oral surgery/orthodontic interface.2. Local causes of malocclusion, Dental Update, 1993; 20:102.13. Mitchell L, Mitchell D A, Oxford Handbook of Clinical Dentistry,3rd edn, Oxford University Press, 2000; 68-69.

Camilleri G E, A review of 47 cases of unerupted maxillary incisors,

Cawson’s Essentials of Oral Medicine and Pathology, 7th edn,

Familial occurrence of mesiodens – a case report,

Familial occurrence of mesiodens, Oral Surgery Oral Medicine Oral Pathology,

Handbook of Clinical Dentistry, 3rd edn,

Local causes of malocclusion, Dental Update,

Mesiodens – Diagnosis and management of a common supernumerary tooth,

Mesiodentes: incidence, morphology, etiology,

Oral Pathology, 3rd edn,

Retention of permanent incisors by mesiodens: a family affair,

Supernumerary teeth, Dental Clinics of

Supernumerary teeth: A review of the literature and four case reports, Australian Dental Journal,

The oral surgery/orthodontic interface.

Unerupted maxillary anterior supernumerary teeth: report of 204 cases,

Mesiodens preventing eruption of a permanent central incisor

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Mesiodens preventing eruption of a permanent central incisor

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