Natal and neonatal teeth : a review of the literature

1 Centro de Investigación y Estudios Avanzados en Odontología "Dr. Keisaburo Miyata" de la Facultad de Odontología de la Universidad Autónoma del Estado de México. Toluca, México. 2 Área Académica de Odontología del Instituto de Ciencias de la Salud de la Universidad Autónoma del Estado de Hidalgo. Pachuca, México. 3 Facultad de Odontología de la Universidad Autónoma de Campeche. Campeche, México. Correspondencia: MSc. Carlo Eduardo Medina Solís. Avenida del Álamo # 204, Fraccionamiento Paseo de los Solares. Colonia Santiago Tlapacoya. CP. 42110. Pachuca de Soto, Hidalgo, México. E-mail: cemedinas@yahoo.com Conflicto de intereses: Los autores declaran no poseer conflicto de interés. Recibido: 14/12/2016. Aceptado: 02/03/2017. Doi: 10.18004/ped.2017.abril.62-70 RESUMEN


Introduction
Typical eruption of primary teeth begins at about 6 months of age.Teeth observed at birth are considered as natal teeth, while teeth observed within the first 30 days as neonatal teeth, based on the classification given by Massler and Savara in 1950 according to the time of eruption 78 .In 1966, Spouge and Feasby categorized these teeth based on clinical features as mature and immature 110 .Mature are those which are fully developed in shape and comparable in morphology to the deciduous teeth; immature are the teeth whose structure and development are incomplete.Finally, Hebling in 1997 presented 4 clinical categories 44 : -Shell-shaped crown loosely attached to the alveolus by gingival tissue and absence of a root; -Solid crown loosely attached to the alveolus by gingival tissue and little or no root; -Eruption of the incisal margin of the crown through gingival tissue; -Mucosal swelling with the tooth non-erupted but palpable.
The rare occurrence of natal and neonatal teeth was associated in the past with superstition and folklore.Today this phenomenon creates great interest and concern, not only to parents but to clinicians as well.This is due to their clinical characteristics (small size, conical shape, and great mobility) which are the cause of certain complications (laceration of mother's breasts, sublingual ulceration, and danger of aspiration of the teeth).

History
The rare occurrence of natal and neonatal teeth has led to association with superstition and folklore.Some cultures have believed that children born with teeth were favoured, particularly in Western Europe and Malaysia, whereas other considered natal teeth as an ill omen.In England it was believed that natal teeth showed that the children would grow into famous soldiers, in France and Italy that they 'would get on in the world' and in Sweden that they could cure an injured finger if it were placed in whose teeth grow early, will early sink into the grave' 14 .Due to these superstitions it is suggested that a transcultural approach be adopted in managing cases in which the parents feel particularly anxious and uncomfortable about prematurely erupted teeth in order to cater for the social well-being of the child and family 88 .

Prevalence
Many authors have reviewed the incidence of natal and neonatal teeth (Table 1).The estimated prevalence ranges from 1:10 to 1:30.000.It is accepted by many authors that the ratio of natal and neonatal teeth is somewhere between 1:2000 and 1:3500 14,23,24,78,110,123 .their mouth.In many places like Poland India and Africa superstition still prevails considering these children to be monsters or evil children 14 .Among several native African tribes, such as in urban Bariba in Benin West Africa, one of the most dangerous signs suggesting a witch child is to be born with teeth and if that happened the child was either abandoned or killed.Precautions in the form of a purification ritual are still taken today in such cases, and sometimes the teeth will be extracted 101 .In China a child born with teeth suggests misfortune for the family: if the child is male then the father will die and if it is a female the mother.Many historic personalities, like Hannibal, Cardinal Richelieu, Broca, Zoroaster, Napoleon, English King Richard the III and King Louis XIV of France are said to be born with teeth.Also many proverbs and apothegms are made up for natal teeth, such as 'The one pyelitis during pregnancy 15 .Another theory refers to hormonal stimulation, meaning the excessive secretion of pituitary, thyroid or gonads 78 .It is also significant to mention that congenital syphilis seems to have varying effect; in some cases premature eruption was noticed, while in others the eruption was retarded 15 .Moreover, febrile states can affect the normal eruption of teeth, for example fever and exanthemata during pregnancy can cause premature eruption 78 .The hereditary factor is assumed a possible cause of natal teeth.Zhu and King (1995)  123 have reported natal teeth as a familiar trait in 8-62% of cases.Bondenhoff and Gorlin (1963) 14 reported family association in 14.5% of cases, while Kates et al (1984) 52 found a positive family history in 7 out of 38 cases of natal and neonatal teeth.A hereditary transmission of an autosomal dominant gene has also been suggested 24,49 .
The prevalence of occurrence of natal and neonatal teeth in males and females is controversial, with some authors giving a higher ratio for females 3,5,23,36,52,65,78 , Kates et al 54 reporting a 66% proportion for females against a 31% proportion for males, and others suggesting that there isn't any correlation with gender 14,25,106 .

Etiology
The exact etiology of natal and neonatal teeth has not been elucidated yet.Many theories have been expressed regarding the cause of the occurrence of these teeth.One of them includes dietary deficiencies 3 or hypovitaminosis due to poor maternal health, endocrine disturbances and  115 they occur in pairs 65,123 .The eruption of more than 2 teeth is rare.Despite that, Masatomi et al 77 in 1991 reported an 18-month-old Japanese boy with 14 natal teeth, Gonçalves et al 40 in 1998 presented the case of a newborn with 12 natal teeth and Portela et al 92 in 2004 reported a newborn with 11 natal teeth.Natal teeth are described as conical or normal in size and shape, yellowish, with hypoplastic enamel and dentin, and poor or absent root development 37,100,123 .The hypoplastic enamel might be related to gingival covering 52 and has a tendency to discolour.The incomplete root formation is the reason for the great mobility of the natal and neonatal teeth.
As far as histological characteristics are concerned, despite the normal basic structure of the natal teeth, early eruption is associated with hypo-mineralization of the enamel, which is usually described as dysplastic 52 , reduced in thickness and covering only the two thirds of the crown 6,42 , but has a normal ultrastructure 111 .Complete absence of enamel is noted rarely 3,78 .The enamel for the age of the child is normal but since the tooth erupts prematurely the matrix of the non-calcified enamel wears off in time and this is probably the reason why their crowns look small in size and appear yellow brown in colour 52 .The dentino-enamel junction seems irregular 42 .
Dentin and predentin appear normal coronally, but become irregular and with reduced number of dentinal tubules and large inter-globular spaces with abnormal cell inclusions 14,16,42 cervically and bonelike apically resembling osteodentin, which is attributed to stimulation by movement of the teeth.It has been further suggested that the mobility may cause degeneration of Hertwig's sheath, thus preventing root development and stabilization 109 .Increased mobility causes histological changes in the cervical dentin and cementum 6,42,109 .Cementum is either absent 14 or, if present, shows variation in thickness covers the cervical third of the crown and is usually acellurar 42 .The pulp tissue has a normal appearance but the pulp cavity and the radicular canals are wider 6,42,110 .
In neonatal teeth the differences from normal primary dentition are less pronounced due to their more mature state at the time of eruption 6 .Root formation in natal and neonatal teeth is grossly deficient 14 .

Differential Diagnosis
Most of the teeth that occur in the oral cavity at birth or during the first days of life represent the early eruption of the normal primary deciduous dentition 44,65 .The prevalence of supernumerary teeth has been suggested to range from 1-10% 17,37,123 .At this point, it is important Another theory explaining the premature eruption is considered to be the abnormal position of the germ during its development in the alveolar bone 8,97 .Furthermore, Clergueau-Guerithault proposed that the eruption of natal and neonatal teeth could be dependent on osteoblastic activity within the area of the tooth germ 102 .
As far as environmental factors are concerned, some environmental toxins are considered to be causative factors.Gladden et al (1990) 39 reported that 13 of 128 newborns, whose mothers where exposed to polychlorinated binephyls and dibenzofurans during the Yusheng environmental accident in Taiwan, had natal teeth.Also, 2 out of 12 live-borns from parents poisoned by PCBs in Kyushu, Japan were reported to have natal teeth 82 .Another report by Alaluusua et al (2002) 2 supports that there is no association between milk levels of polychlorinated binephyls, and dibenzofurans and the occurrence of natal teeth.They suggest that the prevailing levels of polychlorinated binephyls and dibenzofurans are likely below the threshold to cause prenatal eruptions of teeth.
Moreover, the presence of natal and neonatal teeth has been associated with many syndromes and developmental disturbances but there is no conclusive evidence of a correlation with these systemic conditions 25 .The conditions that are related with the appearance of natal teeth are shown in the table 2.
Natal and neonatal teeth have also been reported in cutis gyratum and acanthosis nigricans 10 , Turnpenny ectodermal dysplasia 119 , in association with primary congenital glaucoma 72 , in a case of an anencephalic infant with cleft palate 74 , in association with giant congenital nevocellular nevus 53 , in a case of restrictive dermopathy 79 , in a case of multiple joint dislocations with metaphyseal dysplasia 90 , in a case of multiple anomalies: natal teeth, palatal cyst, bilateral lymphangiomas of the alveolar ridge and median alveolar notch 21 , in a case of complex craniofacial anomalies 112 , in Mohr syndrome 9 and in association with syringomas and oligodontia 83 .It is suggested that tooth abnormalities are dysmorphic markers of earlier developmental abnormalities, and could give warning signs in a syndrome diagnosis 13 .

Clinical and Histological Characteristics
Regarding clinical characteristics, the most affected teeth are the lower primary central incisors (85%), followed by the maxillary incisors (11%), mandibular canines and molars (3%) and maxillary canines and molars (1%) 123 .Another characteristic of natal teeth is that breast 106 , inflammation of the surrounding tissues, pain associated with mobility, which all may lead to refusal to nurse 52 .Although no case is reported, there is usually a concern about aspiration or swallowing of the teeth due to excessive mobility or spontaneous exfoliation 95 .Furthermore there can be teething symptoms just as with eruption of the primary teeth 52 or even infantile diarrhea, drooling and malaise 106,110 .The development of an abscess, probably due to the loss of attachment, has also been reported 32,51 .
A complication that is common with natal teeth is ulceration of the tip or the ventral surface of the tongue, known as Riga-Fede disease.The ulceration occurs after repetitive tongue thrusting not only in newborns but also to elder infants with the eruption of the primary mandibular central incisors and in children with familiar dysanatomia 107 .There has also been a report of prenatal ulceration of the tongue due to natal teeth 58 .The lesion begins as an ulcerated area and with repeated trauma it may progress to an enlarged fibrous mass with the appearance of a granuloma.The pain occurring from the ulceration often results on dehydration, feeding difficulties and discomfort.It also may lead to bleeding and in a child with other medical problems a potential of infection is added to the concerns 107 .Periapical abscess is possible because enamel breakdown may lead to carries 52 .Another complication in children with cleft lip-palate is the potential interference in naso-alveolar moulding 124 .
There have also been reported a case of reactive fibrous hyperplasia by a natal tooth 106 , hypoplasia of primary and permanent teeth following osteitis due to infection by neonatal tooth 55 and also microdontic teeth succedaneous to natal teeth, suggesting that there might be some unknown developmental influence common to the occurrence of natal teeth and abnormally small (mesiodistal dimension) permanent successors 75 and in neonatal orthopaedics 31 .

Management
The treatment plan for natal and neonatal teeth has many factors to consider.If the tooth is not interfering with the nutrient intake of the child and is otherwise asymptomatic no intervention should be made 78 .Although it is difficult to determine initially whether root formation will occur in natal or neonatal teeth 104 those teeth that are stable beyond 4 months have a good prognosis 52 .The retention of a natal tooth, which is part of the normal primary dentition, is suggested because of possible space loss, although the opinions differ 23,32,38 .If the tooth is supernumerary or has an excessive mobility, if it is poorly developed or is associated with soft tissue growth 106 or if to mention the need of radiographic examination, in order to differentiate the premature eruption of a primary deciduous tooth from a supernumerary tooth 15,25,65 .Moreover, radiographic verification reveals the root development of the tooth, adjacent structures and the existence of a relative germ in the primary dentition.
There are also 3 types of inclusion cysts that might be confused with natal teeth: Epstein's pearls, Bohn's nodules and dental lamina cysts.Epstein's pearls are located along the mid-palatine raphe in the line of fusion of embryonic palatal processes.They are true cysts derived from residual ectodermal cells covering these processes.The cysts are lined by stratified squamous epithelium and the lumen contains keratin 24 .Bohn's nodules are usually multiple and located along the buccal and lingual aspects of the mandibular and maxillary ridges 68 .They represent remnants of minor mucous salivary glands.They are true cysts comprised of stratified squamous epithelium lining a dense fibrous connective tissue wall that contains mucous acinar cells and wellformed ducts.The clinical appearance of Epstein's pearls and Bohn's nodules is similar.They are both small white-gray, raised nodules, 0.5-3 mm in diameter and no treatment is necessary 24 .
The third type of cyst is dental lamina cyst which appears as single or multiple swellings on the maxillary or mandibular ridges.These cysts, also known as gingival cysts of the newborn, are lined by thin epithelium and show a lumen usually filled with desquamated keratin, occasionally containing inflammatory cells.It is believed that they are created by fragments of dental lamina that remain within the alveolar ridge mucosa after tooth formation.Most of them degenerate and involute or rupture into the oral cavity within two weeks to five months of postnatal life 63 .
Furthermore, natal teeth should be discriminated from epulis and odontogenic hamartomas.Epulis are tumour-like growths of the gum that might be either sessile or pedunculated, and are reactive rather than neoplastic lesions 68 .Odontogenic hamartomas are tumour-like lesions, without the growth characteristics of a neoplasm, and develop during the time dental structures remain capable of further development and maturation 38 .

Complications
Problems that arise from the presence of natal and neonatal teeth include interruption in breastfeeding 93 either by pain on suckling or by ulceration of the mother's nipples, but the infant's tongue usually overlies the lower incisors while nursing and any trauma will be to the infants tongue rather than mother's Paediatric dentists should educate parents and medical community about the preferred treatment and should conduct any necessary extraction in order to prevent trauma.The child should be re-evaluated periodically to ensure oral health.Management of natal and neonatal teeth should consist of concern to avoid any complication, to make early diagnosis and provide adequate treatment.

Conclusion
Natal and neonatal teeth are rare conditions in infancy.Most commonly involved teeth are the mandibular central incisors.Despite the fact that the exact etiology is still unknown, superficial position of the tooth germ with association of hereditary factors is the most accepted possibility.Many complications may occur with the nursing problem most commonly reviewed.Treatment and periodic follow-up should be conducted by a paediatric dentist.it interferes with naso-alveolar moulding 124 or presents an abscess, the treatment of choice is extraction 32,51,52 .Before extraction, a dental radiograph should be obtained in order to inform the parents of possible complications and to get their consent.It is suggested to leave the tooth in the mouth as long as possible in order to decrease the possibility of removing permanent tooth buds with the natal tooth or risk defecting them 76 .The possibility of hypoprothrombinaemia should be taken into consideration as the commensal flora of the intestine might not have been established until the child is 10 days old.Since vitamin K is essential for the production of prothrombin in the liver it should be administered before extraction (0.5-1.0 mg, intramuscularly) if the routine postnatal injection is not given 32 .Also, haemophilia should be investigated 38 .The extraction is usually done under local anaesthesia but can also be done without anaesthesia depending on the gingival attachment, with the use of gauze as a pharyngeal guard 32 .After the extraction, it is advised to curette the socket to prevent the cells of the dental papillae from continuing to develop and erupting as odontogenic remnants 11,25,108 .If curettage is to become the routine treatment, then the injection of local anaesthetic to provide adequate anaesthesia would be required 32 .Residual natal teeth have been reported with a risk of formatting without curettage about 9.1% 32,86 , myxoid calcified hamartoma 1 , pulp polyp as erupted remnants 121 , pyogenic granuloma due to trauma during extraction 84 and peripheral ossifying fibroma 60 .
Riga-Fede disease is another complication of natal teeth and neonatal teeth but it's not an indication for extraction 78 .The treatment options include smoothing off the incisal edges of lower incisors with an abrasive instrument 3 , modifying feeding behaviour or feeding devise, treatment of symptoms with oral triamcinolone acetonide in orabase applied on the lesion (Kenalog® in Orabase® Triamcinolone Acetonide Dental Paste USP, APOTHECON® A Bristol-Myers Squibb Company), or placement of composite over the edges of the insicors 89,107 .As many natal and neonatal teeth have hypo-mineralised enamel and are difficult to access and keep adequate moisture control, the bonding of the resin is questionable and presents the risk of swallowing or inhaling it.In cases of mild-to-moderate irritation to the tongue, such treatment may suffice.If the ulcerated area is large, however, even the reduced incisal edge may still contact and traumatize the tongue during suckling to such an extent that would delay healing 86,118 .The fact that the lesion could reoccur should also be taken into consideration 89,107 .If none of the more conservative measures is effective, the option is extraction of the tooth or even excision of the lesion 107 .

Table 1 .
Prevalence of natal and neonatal teeth