Missing of one or more teeth is perhaps our most common congenital malformation. More than 20 % of us lack one or more wisdom teeth (third molars). More than five percent of us lack one or more second premolars or upper second (lateral) incisors. Lack of a large amount of teeth, though, is much more rare.
Numerous genetic and environmental factors may cause abnormalities in tooth development. These may include defects of structure (e.g. abnormal enamel, amelogenesis imperfecta or abnormal dentin, dentinogenesis imperfecta or dentin dysplasia); abnormal position of tooth; reduced size and abnormal shape of teeth (e.g. "peg- shaped" incisors, taurodontism, or short root anomaly); missing of one or more teeth (hypodontia, oligodontia, tooth agenesis).
Missing of one or more teeth is perhaps our most common congenital malformation. More than 20 % of us lack one or more wisdom teeth (third molars). More than five percent of us lack one or more second premolars or upper second (lateral) incisors. Lack of a large amount of teeth, though, is much more rare.
Several environmental factors like virus infections, toxins and radio- or chemotherapy may cause missing of permanent teeth. However, most of the cases are caused by genetic factors. The heritability of congenitally missing teeth has been shown in many studies. The genetic factors may be dominant or recessive and it is obvious that in many cases multiple genetic (and environmental) factors are acting together. The importance of genetic factors is shown by appearance of multiple cases among relatives (familial clustering) and higher concordance in identical than in non- identical twins.
Dominant inheritance of congenitally missing teeth has been shown both in hypodontia and oligodontia. However in both cases the amount and identity of missing teeth may vary between relatives. In hypodontia, the variability may extend to no teeth actually missing ("reduced penetrance"). The variability is probably caused by other genetic and environmental factors, and in some cases the etiology is analogous to multifactorial traits.
An example of recessive inheritance is given by recessive incisor hypodontia (RIH). In this condition described by us, a recessive gene causes congenital missing of several incisors, including lower permanent incisors and often decidusous incisors, too) the inheritance is recessive.
Prosthodontics is the dental specialty pertaining to the diagnosis, treatment planning, rehabilitation and maintenance of the oral function, comfort, appearance of patients with missing or deficient teeth.
The artificial teeth are classified into:Oligodontia refers to congenital lack of more than six teeth (wisdom teeth not included). The population frequency is low, especially for cases when absence of teeth is the only malformation ("isolated" cases). Most often oligodontia appears as part of some congenital syndrome that affects several organ systems. These include ectodermal dysplasias, i.e. defects of skin, hair, nails, teeth and ectodermal glands; oral clefting (cleft lip, cleft palate, or cleft lip and palate); Rieger syndrome, Char syndrome etc
Anodontia refers to complete lack of teeth, which is very rare.
Tooth agenesis, also used as partial or selective tooth agenesis, may refer to all of the above. Most commonly missing teeth are the third molars (wisdom teeth), second premolars and permanent upper second (lateral) incisors. Most rarely missing teeth are the upper first (central) incisors. Missing of lower second (lateral) incisors, all canines, first premolars and first molars or any of the deciduous teeth is also rare.
Shapes and positions of the existing teeth may also be abnormal in association with missing teeth. The features often seen include "peg- shaped" upper second incisors, taurodontism and malpositions.
Hypodontia, is the congenital absence of teeth. Generally:
Other associated clinical features of hypodontia include retention of deciduous predecessors, delayed formation and eruption of teeth, reduction in tooth size and form, short roots of teeth, taurodontism, enamel hypoplasia, hypocalcification, dental malpositions, diastemas and infraposition of primary molars.
Hypodontia can be caused by environmental factors (trauma, infection, radiation therapy, chemotherapeutic agents and the use of thalidomide during pregnancy) but is most commonly due to genetic factors.
Treatment of hypodontia requires long term multidisciplinary management. The use of fluoride toothpaste, healthy diet and good oral hygiene practices are emphasized at an early age. Regular dental visits are necessary. Orthodontic (fixed appliances, retainers) and prosthetic (removable partial dentures, over-dentures and fixed partial dentures) treatments are started at an early age (3 years) to improve esthetics and function and to minimize any psychological impact. They are essential for space management and to prepare for future therapies. Dental implants can be considered and placed in the anterior mandible as early as 6-7 years of age in cases of mandibular oligodontia. In other locations, they can be used to support dentures, and can be placed after the growth period. Therapy using recombinant replacement ectodysplasin is being developed.
Dental ankylosis is a rare disorder characterized by the fusion of the tooth to the bone, preventing both eruption and orthodontic movement. The periodontal ligament is obliterated by a 'bony bridge' and the tooth root is fused to the alveolar bone. Dental ankylosis can affect both primary and permanent teeth.
The disorder may result in loss of the retained molar and neighboring teeth due to caries and periodontal disease, and deformation of the facial skeleton (reduction in the height of the lower face, relative mandibular prognathism, posterior open bite). The major characteristic of a secondarily retained molar is infraocclusion that may result in malocclusion. Occasionally, dental ankylosis may be associated with fifth finger clinodactyly.
Etiology remains uncertain but a genetic predisposition to ankylosis with autosomal dominant inheritance has been suggested. Familial occurrence has been shown in several families. Trauma, inflammation or infection may play a causative role.
Clinical examination and X-ray are the main diagnostic methods for detecting ankylosis. The recommended management includes removing the ankylosed tooth to ensure development and eruption of the permanent teeth, and surgery to expose, protect, or reposition the emerging tooth.
Peg lateral teeth, or peg lateral incisors, are terms used to describe a condition where the lateral incisors (the second tooth on either side of the front teeth) are undersized and appear smaller than normal. This situation occurs when the permanent lateral incisors do not fully develop. Sometimes, the permanent adult lateral incisor teeth do not develop at all, leaving only the baby teeth (primary or deciduous teeth) in their place. Since peg lateral incisors are undersized, many times there will be a space between them and the adjacent teeth (this space normally would have been occupied by a fully developed lateral incisor). This resultant space causes the alignment of the teeth, and thus the smile, to appear abnormal.
There are several ways to treat and correct this condition. If the roots are strong but the visible teeth are undersized, the peg lateral incisors can be covered with porcelain crowns or porcelain veneers. Porcelain veneers are the most common treatment for peg lateral incisors, and require little or no tooth preparation. A porcelain shell is simply bonded over the smaller peg laterals making the teeth appear normal in size.
If not enough space exists between the central incisors (front teeth) and the canine teeth to accommodate normally sized lateral incisors, space must be created by orthodontic treatment. Traditional band orthodontic treatment or Invisalign appliances can be used to create the necessary space.
If the peg lateral incisor has a very small root, there may not be enough support to hold a free standing restoration such as a porcelain veneer or porcelain crown. In this situation, there are three possible methods of treatment.
Supernumerary teeth are the extra teeth that one can have in the mouth. They can be found at any location in the oral cavity. This condition is referred to as hyperdontia.These are more common in the maxilla than in the mandible.
The specific cause of the development of the extra teeth has not yet been established. But there are a number of theories that have been put across to explain their presence. Some theories say that these teeth might be present due to the division of the tooth bud in a way that is not normal while other theories blame the existence of the supernumerary teeth on the dental lamina hyperactivity. It is also believed that a person’s genetics has something to do with this condition because it is considered hereditary.
Treatment depends on the type and location of the supernumerary teeth and on its potential effect on adjacent hard and soft tissue structures. Occasionally, supernumerary teeth may lead to complications such as deep caries in the adjacent teeth, which may require restoration or endodontic therapy of the adjacent teeth as well. Supernumerary teeth can be managed either by removal/endodontic/orthodontic therapy or by maintaining them in the arch and frequent observation. Removal of the supernumerary teeth is recommended where; there is associated pathology, permanent tooth eruption has been delayed due to the presence of supernumerary tooth, increased risk of caries due to the presence of supernumerary teeth which makes the area inaccessible to maintain oral hygiene, altered eruption or displacement of adjacent tooth is evident, there are severely rotated teeth leading to further complication, orthodontic treatment needs to be carried out to align the teeth, its presence would compromise alveolar bone grafting and implant placement and there is compromised esthetic and functional status.
Cleidocranial dysostosis (CCD) is a rare congenital disorder of bone characterized by clavicular aplasia or deficient formation of the clavicles, delayed and imperfect ossification of the cranium, moderately short stature, and a variety of other skeletal abnormalities. The oral manifestations are delayed exfoliation of primary teeth, delayed or failing eruption of the permanent dentition, and presence of multiple supernumerary teeth.
Cleidocranial dysplasia is caused by a mutation in the RUNX2 gene, which is involved in skeletal bone growth.
Because dental problems — such as delayed tooth eruption and additional teeth — are the most significant complications of cleidocranial dysostosis, proper dental and orthodontic treatment is critical.
Some dentists do not recommend the removal of primary or supernumerary teeth as it does not necessarily promote eruption of unerupted permanent teeth. Also the permanent teeth may be difficult to extract due to presence of malformed roots.
Sinus and middle ear infections are also common and require aggressive treatment. If your child has frequent middle ear infections, tympanostomy tubes may be recommended. These are small tubes that are surgically placed into the eardrum to equalize pressure and aerate the middle ear, which helps prevent further infections and hearing loss.
Your child should also be evaluated by an orthopedic specialist for scoliosis, bone density abnormalities and osteoporosis, and other bone abnormalities such as missing collar bones.
Amelogenesis imperfecta (AI) is a relatively rare group of inherited disorders characterized by abnormal enamel formation. Include abnormalities that are classified as hypoplastic (defect in amount of enamel), hypomaturation (defect in final growth and maturation of enamel crystallites), and hypocalcified (defect in initial crystallite formation followed by defective growth).
Mutations in the AMELX, ENAM, and MMP20 genes cause amelogenesis imperfecta.
The main aim of the dentist should be, trying to restore aesthetics and function while keeping the treatment as conservative as possible. The mainstay of treatment should be to prolong the life of the patient’s own teeth and delay the need for extractions and subsequent replacement with conventional fixed, removable or implant retained prostheses. In order to achieve this goal a stepwise approach to treatment planning is required starting with the most conservative but aesthetically acceptable treatment. The literature regarding treatment options is abundant with case reports which predominately describe the use of removable prosthesis and full coverage crown and bridgework. Complete crowns represent a predictable and durable aesthetic option, however, the disadvantage of this approach is that it is highly destructive. In milder forms of AI, porcelain veneers have been advocated to restore aesthetics and in more severe cases overdentures or overlay dentures have been advocated. While veneer preparation is usually minimal it still requires preparation of a structurally compromised tooth at a young age. Placement of veneers during adolescence when gingival maturation is not complete can result in marginal exposure of the veneer in the future as the gingival tissues mature leaving an unaesthetic appearance. This subsequently results in the need for early replacement of the veneer which can further damage the tooth structure.
There is very little evidence regarding the use of composite resin in the management of AI. With advances in composite bonding techniques this is one option that should be considered earlier in the management of these cases.
Dentinogenesis imperfecta represents a group of hereditary conditions that are characterized by abnormal dentin formation. Researchers have described three types of dentinogenesis imperfecta with similar dental abnormalities. Type I occurs in people who have osteogenesis imperfecta, a genetic condition in which bones are brittle and easily broken. Dentinogenesis imperfecta type II and type III usually occur in people without other inherited disorders.
Mutations in the DSPP gene have been identified in people with dentinogenesis imperfecta type II and type III. Mutations in this gene are also responsible for dentin dysplasia type II. Dentinogenesis imperfecta type I occurs as part of osteogenesis imperfecta, which is caused by mutations in one of several other genes.
Treatment of mild to moderate DI severity or in those patients not exhibiting enamel fracturing and rapid wear of the dental crown, routine restorative techniques can often be used effectively.
In more severe cases where there is significant enamel fracturing and rapid dental wear, the treatment of choice is full coverage crowns. Intra-coronal restorations, such as amalgams and composites, are not well retained in patients having severe attrition. In these individuals the tooth structure tends to wear and break away from the restoration ultimately resulting in restorative failure. Stainless steel crowns will be the treatment of choice for cases in the primary dentition with excessive tooth wear. Stainless steel crowns with open face composite restorations or composite crowns can be used for a more esthetic result when crowning anterior teeth. Management of permanent DI teeth with fracturing and excessive wear can be treated with porcelain fused to metal crowns.
Some cases of dentinogenesis imperfecta will suffer from multiple periapicle abscesses apparently resulting from pulpal strangulation that occurs secondarily to pulpal obliteration or from pulp exposure due to extensive coronal wear. The potential for developing periapicle abscesses is another indication for performing thorough periodic radiographic surveys on all individuals with DI. Since these cases have pulpal obliteration and the dentist will rarely be able to negotiate the canal, apical surgery
