A rare occurrence of supplementary maxillary lateral incisors and a detailed review on supernumerary teeth.

This article highlights a rare occurrence of nonsyndromic supplemental maxillary lateral incisors in a 11-year-old boy. It also includes a detailed literature review of supernumerary teeth.

INTRODUCTION

Supernumerary teeth/tooth (ST) which are well aligned in the arch and resemble the normal anatomy of adjacent teeth are called supplementary teeth.[1] They have also been defined as ST that bear resemblance with the teeth they are associated with.[2] According to the Darwin's theory of evolution, as human evolved, organs that were minimally used became vestigial, such as the appendix, tail bone and fourth molar. However, in rare cases, there are still occurrences of supplementary molars and premolars.[13] Only six cases of supplemental central incisors have been reported in literature till date.[456789] Supplemental lateral incisors are rare, and bilateral cases are even rarer. To the best of our knowledge, only three cases have been reported in literature till date.[101112]

CASE REPORT

A 11-year-old boy visited the Department of Pedodontics and Preventive Dentistry with the complaint of anterior crowding [Figure 1]. On intraoral examination, the teeth present in the upper arch were: 16, 15, 14, 53, 12, 11, 21, 22, 63, 24, 65, 26 and two supplemental incisors, bilaterally. Anterior crowding was evident and amalgam restorations were present on the first permanent molars [Figure 2]. The following teeth were unerupted: 17, 27, 13, 23 and 25 [Figure 3]. The lower arch contained the following teeth: 36, 35, 34, 33, 32, 31, 41, 42, 43, 44, 85 and 46. Dental caries (distoproximal) was present on 85; however, no treatment was carried out since it was nearing exfoliation (root resorption was completed). The 37, 47 and 45 were unerupted [Figure 4]. The OPG confirmed the absence of any congenitally missing teeth, additional ST or malformations [Figure 3]. There were no orofacial deformities, mental retardation or any other medical conditions.

Figure 1

Anterior view of both arches

Figure 2

Maxillary arch

Figure 3

Orthopantomograph

Figure 4

Mandibular arch

DISCUSSION

Unerupted supplemental teeth have been associated with several pathological conditions such as widened follicular space, dentigerous cyst formation, and disturbances in adjacent permanent teeth such as ectopic eruption, diastema formation, pulp necrosis, pulp canal obliteration, root resorption, ankylosis and rotations.[46] Most supplemental teeth remain unerupted.[6] However, in the present case, the supplemental lateral incisors were erupted and had only resulted in ectopic eruption and rotations among the adjacent incisors. They did not cause any symptoms in the individual, which supports the fact that 75% of supernumerary lateral incisors located on both maxillary bones in the same position do not cause any symptoms.[1314] If a supplemental tooth is present and erupted, it may be difficult to determine which tooth is supplemental and which are constituents of the normal dentition.[9] However, in the present case, they were categorized as supplemental lateral incisors, since their coronal dimensions closely matched with those of the lateral incisors. Supernumerary canines and lateral incisors are rare with low frequency of occurrence (2.8%) in comparison with other ST.[15] Multiple ST not associated with syndromes are found in rare conditions.[316171819] The patient in the present case did not have any mental retardation, abnormal facial appearance or any skeletal abnormalities suggestive of any syndrome, suggesting an autosomal dominant pattern of inheritance. Similar cases have been documented by many authors.[161920212223] Nonsyndromic ST in the permanent dentition, as in the present case, are mostly found in the maxilla[162425262728] in the anterior region.[25] However, there have been reports of cases involving all maxillary dental series.[1317272930] A predilection for such ST in the mandibular premolar series had also been reported.[1819313233] The patient had reported with the chief complaint of anterior crowding and was unaware of the extra teeth he had. The supplemental maxillary lateral incisors were discovered on intraoral examination and were confirmed on the orthopantomograph. However, fixed orthodontic treatment has been planned to be undertaken after the eruption of all premolars and permanent canines. Selective removal of lateral incisors (normal or supplementary) may be required. In such circumstances, when both teeth are healthy, it has been suggested to extract the tooth/teeth that is most displaced from the line of the arch, so as to relieve crowding.[9]

Definitions

ST have been defined in various ways by authors:

Definition 1: ST (or hyperdontia) are teeth that exceed the normal dental formula (or complement), regardless of their location and form (or morphology)[11131620273435363738394041424344]

Definition 2: Hyperdontia or ST are terms referred to any excess number of teeth or odontogenic structures[1445]

Definition 3: ST may be defined as any teeth or tooth substance in excess of the usual configuration of 20 deciduous and 32 permanent teeth.[46]

Definition 4: ST (or hyperdontia) are defined as the existence of an excessive number of teeth in relation to the normal dental formula[47]

Definition 5: ST are defined as those that appear in addition to the normal series[9]

Definition 6: ST are defined as “supplementary,” if they present a normal morphology, and as “supernumerary,” if they present morphologic and volumetric anomalies.[43]

Classifications

Based on position

The classification of ST may be done on the basis of their position.[248] ST with positional variations include mesiodens, paramolars, distomolars and parapremolars.[217414849] There are variations in the frequency of occurrence of various ST based on the studies conducted. However, mesiodens has been found to be the most common ST with a prevalence between 0.15% and 1.9%.[13363750] According to Türkkahraman et al., the frequency of ST in the descending order of occurrence had been suggested as maxillary midline supernumeraries (mesiodens), maxillary fourth molars, maxillary paramolars, mandibular premolars, maxillary lateral incisors, mandibular fourth molars and maxillary premolars.[51] Many authors have reported the mesiodens as being the most common ST, followed by supernumerary premolars and supernumerary fourth molars.[1415315253] However, Yagüe-García et al. found paramolars to be more frequently occurring than parapremolars.[16] According to a few authors, the order was mesiodens, distomolars or fourth supernumerary molars, paramolars and supernumerary premolars.[13363750] According to Fernández-Montenegro et al., the frequency of occurrence of ST were mesiodens (46.9%), supernumerary premolars (24.1%) and distomolars (18%).[15] Many authors have reported an increased presence of supernumerary premolars.[18192526323354] Parapremolars, that are known to constitute about 8%–9% of all ST,[5556] may occur as single (76%–86%), double (12%–23%) or multiple (<1%) teeth.[34] However, a paramolar is a supernumerary molar, usually rudimentary, situated buccally or lingually/palatally to a molar, or may occur in the interproximal space buccal to the second and third molar.[57] Some authors had found supernumerary molars to be the most prevalent ST.[135859] Supernumerary canines and supernumerary lateral incisors are rare with low frequency of occurrence (2.8%) among ST.[15]

Based on morphology

ST have been classified on the basis of morphology.[248] Primosch classified ST into two types: ST with normal shapes and sizes (eumorphic) were termed as “supplemental” or “incisiform,” whereas ST with abnormal shapes and smaller sizes (dysmorphic) were termed as “rudimentary.”[60] Dysmorphic/heteromorphic/rudimentary ST show distinct forms such as conical or pin, tuberculate, infundibular and molariform.[21314174148496061] Fernández-Montenegro et al. found most supernumerary premolars to be eumorphic (81.8%).[15]

Etiology

ST result from any disturbance in the initiation and proliferation stages of odontogenesis.[6263] There are several theories regarding the development of a ST – trauma, environmental factors, phylogenetic theory (regression to the anthropoids whose dental formula had more teeth), atavism (reversion to a more primitive type of dentition), dichotomy of the tooth germ, hyperactivity of the dental lamina and autonomic recessive inheritance linked to the X chromosome have been suggested.[131416181927646566]

Dichotomy

Dichotomy of the dental lamina (primary or successional) or tooth buds at the stage of histodifferentiation may occur during the 6th week of fetal life.[6768] The tooth bud splits into two parts of equal or unequal sizes, resulting in ST.[111314183069] This hypothesis is supported by animal experiments in which the split germs have been cultivated in vitro.[7071] Gemination, which is assumed to be a similar incomplete process, also supports this theory.[69]

Hyperactive dental lamina

Hyperactive dental lamina continues to proliferate because of failure in programmed cell death, due to defects in signaling between epithelium and mesenchyme. The excessive proliferation of cells results in the formation of extra tooth buds.[131418196072]

Genetics

The role of genetics has been considered in the formation of ST, since they have been found in twins, siblings and sequential generations of a family.[1619287374] Several families have been documented in which at least two individuals presented with multiple ST, not associated with any syndrome.[19265475767778] However, the pattern of inheritance does not follow Mendelian principles.[1719] A dominant autosomal trait characterized by low penetrance has also been suggested.[13162766]

Syndromes and anomalies

The involvement of any syndrome must be carefully examined in any case exhibiting multiple ST.[79] The various syndromes or anomalies associated with ST are cleft lip and palate, cleidocranial dysostosis, Gardner's syndrome, Fabry–Anderson's syndrome, chondroectodermal dysplasia (Ellis–Van Creveld syndrome), Ehlers–Danlos syndrome, incontinentia pigmenti and tricorhinophalangeal syndrome.[313141618202324273435373840426061666980818283] Dental anomalies such as hypodontia, taurodontism, gemination or macrodontia have also been associated with ST.[8485]

Prevalence

Permanent dentition

ST had been first reported between 23 AD and 79 AD[29] The prevalence of ST in the general population had been reported by various authors to be between 0.09 and 0.29%,[1336373839408386] 0.5%–5.3%,[16] 0.5%–3.8%,[204113343637398687] 1%–4%,[60] 0.5%–5.3%,[88] 0.3%–1.7%,[71] 0.1%–3.9%[91445899091] and 0.15%–3.800%.[3153] Their prevalence had been reported to be higher in Mongoloids and African-Americans.[1445899091] A similar observation had been made in the Asian and Native American populations.[71] Their prevalence in the Caucasian population had been found to be between 0.1% and 3.9%.[144589929394] Their prevalence in countries between the Caspian sea, and the Black sea were found to be between 0.1% and 3.8%.[14899293] Their prevalence was found to be between 0.4% and 3.4% in Arabs and Asians,[14899293] and 1.24% in South Indians.[95] ST were also found to have a prevalence between 2.7% and 3.4% in Sub-Saharan and Asian populations.[3796] These variations in global prevalence, especially for the Asian population, might stem from diversities in ethnicity, methodological differences, age groups examined and sample size.[376397]

Primary dentition

The prevalence of ST in the primary dentition had been found to vary according to authors. It had been found to be between 0.3%–1.7%,[71] 0.2%–0.8%,[1688] 0.2%–1.9%,[60] 0.3%–0.8%[9] and 0.3%–0.6%.[1320343637398687]

Gender variation

ST had been found to occur more in males.[145089939597] However, male-to-female ratios of 2:1,[13141518263435364044618283] 9:2[1318] and 1.4:1[15] had been reported.

Site of occurrence

ST had been found to occur more, unilaterally than bilaterally.[98] They had been found to occur in the maxilla 8.2–10 times more frequently than in the mandible, commonly affecting the premaxillary region,[111416273057] in a palatine position.[155099100101102] About 90%–98% of ST are found in the premaxillary region,[353760] followed by the mandibular premolar region (supernumerary premolars).[15182089103104] Supernumerary premolars are mostly located in the mandible, in a lingual position,[15] while paramolars and distomolars are mostly found in the maxilla.[105106107]

Multiple supernumerary teeth

The prevalence of multiple ST had been found to be 0.06%.[31] Multiple ST had been reported in 8%–27%[60101] or 1.5%[14] of the individuals with at least one ST. The presence of one, two and three or more ST occur in 76%–86%, 12%–23% and 1% of the individuals with ST, respectively.[1415108] Three or more ST in the same individual were found in 2%–8% of cases with ST.[1415] However, five or more ST in the same individual were found in <1% of individuals with ST.[1418]

Complications

ST teeth can erupt normally, remain impacted, invert, reach heterotopic positions or show abnormal eruptive patterns.[184959] There are various complications related to ST according to authors:[131426314243444548525660747797109110111112113114115116117118119120121122123124125126127]

Eruption disturbances: Delayed eruption or noneruption of permanent teeth (30%–60% of cases

Malpositions: Discrepancy in the Bolton's arch perimeter resulting in severe crowding and malpositioning; displacement or rotation of adjacent teeth

Root related: Absorption of roots and root malformations (dilacerations) secondary to the pressure exerted by ST

Pathologic: Development of follicular cysts

Endodontic: Caries and loss of vitality of adjacent teeth

Periodontal: Gingivitis, periodontitis and abscess formation

Functional: Occlusal interferences and masticatory difficulties

Others: Neuralgic manifestations and dysodontiasis of permanent teeth.

Treatment options

Since the majority of ST (80%–93%) cause clinical complications, early diagnosis and treatment planning are important in preventing complications related to ST and adjacent teeth.[89118] Orthodontists, pediatric dentists, and general practitioners who usually visit children at lower ages can contribute to early diagnosis and planning more effective long-term interdisciplinary therapies.[128] There are two treatment options for delayed eruption of adjacent teeth due to the presence of ST. The first option being, removal of the ST if adequate space is available for the adjacent tooth to erupt or removal of the ST followed by a surgical-orthodontic treatment to re-establish space for the unerupted tooth.[17] The timing of surgical removal of ST is contentious and two alternatives exist. First, to remove the ST as soon as it has been diagnosed and second, to leave the ST as such till the root development of adjacent teeth is complete, to prevent damage to their root apices. However, no evidence of root resorption, loss of vitality, or any disturbance to root development in adjacent permanent teeth had been reported by Hogstrom and Andersson.[113] The underlying permanent teeth usually erupt spontaneously following the removal of unerupted ST.[14]

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.