Enamel hypoplasia refers to defective development of the crown-covering layer of the teeth. It may manifest in the form of reduced hardness or thickness of the dental enamel.
EH may manifest in single or multiple teeth, in the form of an irregular, rough surface, small dents, flat pits , grooves, greater defects or complete absence of the enamel layer. Contrary to cases of enamel hypomineralization, the contour of the affected tooth is altered because the overall thickness of the enamel is reduced. EH patients present softer enamel than healthy individuals. Discoloration may be observed, but this feature is not helpful in distinguishing EH from hypomineralization. In both cases, teeth may have opaque, white, yellowish or brown spots. Patients may report increased sensitivity. Teeth affected by EH are more prone to attrition, decay and fracture.
Most commonly affected are the permanent incisors and first molars . This observation may be explained by the fact that enamel layers of these teeth develop during the first years of life, a period of life that may be characterized by childhood infectious diseases and traumas.
Careful examination of the teeth reveals irregular surfaces, pits and grooves in the affected teeth. Differential diagnoses are excess attrition due to bruxism or malocclusion as well as enamel demineralization. Tooth grinding affects the occlusal surfaces of the teeth and malocclusion may be diagnosed during routine dental examination. Enamel demineralization may occur due to the influence of acids produced by bacteria located in plaques. It is often associated with poor oral hygiene.
In some cases, the medical history of the patient indicate infectious diseases, nutritional deficiencies or sustained traumas during pregnancy or early childhood as the underlying cause, but usually it is not possible to identify the precise cause of visible enamel defects.
The therapeutic approach depends on the extent of EH, on potential comorbidities and on the number of affected teeth . Therapy aims at conserving the tooth, protecting it from further wear and associated dental diseases as well as preventing sensitivity and pain.
Mild cases may be treated by sealing or bonding a circumscribed affected area of the tooth. In some cases, these materials do not bond well with the surrounding enamel. Thus, patients should be re-evaluated after six months. If the sealant is lost, pits and grooves should be cleaned before dental composite is used to reconstruct the crown. Composites may suffer the same fate as sealants. This treatment may be repeated before choosing alternative therapeutic options.
If neither sealants nor composites yield satisfactory results, or if the patient continues to experience enhanced sensitivity or if there are extensive enamel defects then a replacement of the dental crown has to be considered. Stainless steel crowns or full cast crowns may be used, but the former will have to be replaced by the latter eventually.
In severe cases, extraction of the affected teeth and replacement with implants or bridges may be the only therapeutic option.
Mild cases of EH may be effectively treated with seals and bonds. However, extensive enamel defects will most likely require crown replacement. If dental care is provided before the onset of comorbidities, the prognosis for tooth conservation is good.
Environmental factors, particularly nutritional deficiencies, and infection may interfere with enamel formation. In this regard, the second half of pregnancy and early childhood years are most critical. Any infection that may affect the (unborn) child, high fever, and vitamin deficiencies are detrimental to enamel formation. Chicken pox, measles, and congenital syphilis may serve as examples of infectious diseases interfering with enamel formation. Vitamins A, C,and D are needed for amelogenesis, but vitamin D deficiency most commonly causes EH. Vitamin D deficiency may lead to hypocalcemia, a condition that can be observed in premature infants and rickets , and thereby cause EH. Diseases and nutritional deficiencies may be mutually dependent and contribute to EH in a combined way, as is the case in those suffering from Celiac disease . Additionally, certain drugs and traumas may interfere with tooth development. Of note are infections of or trauma to primary teeth which may damage the superficial layers of the underlying permanent teeth and thus cause EH .
Genetic factors also contribute to EH, but seem to be of less importance than environmental influences. Amelogenesis imperfecta is the term used for an enamel formation defect that is inherited as a dominant trait. Patients suffering from EH due to amelogenesis imperfecta present with crown defects on all teeth, deciduous as well as permanent.
Poor oral hygiene does not affect enamel formation but may significantly promote damage of less protected teeth.
Because the diagnosis of EH is made years after the causative event, it is often difficult to identify the precise cause in an individual case.
Studies comparing dental diagnoses in skeletons and living people of different sexes, ages and races has revealed an overall decline in EH prevalence . However, the reasons behind reduced EH prevalence could only be speculated as specific etiologies could not be identified. The trend may be explained by improved prenatal and early childhood care and nutrition. Nutritional deficiencies are observed less frequently as prenatal vitamins ensure sufficient intake by expectant mothers. Incidence rates of many childhood infectious diseases have been reduced considerably and better treatment options exist for children who become ill.
Amelogenesis is a process that takes place over prolonged periods of time. The location and time of systemic or local disturbances will thus be represented by enamel lesions. If environmental factors triggered the disease, EH is limited to circumscribed areas of particular teeth. Thus the distribution of enamel defects helps to determine the disturbing factor  . All teeth are affected in patients suffering from amelogenesis imperfecta, a condition caused by gene mutations.
EH is the result of impaired matrix formation due to ameloblast functional impairment during amelogenesis . Incomplete maturation and calcification, however, results in hypomineralization. While the former leads to the crown being covered by a thin, softer enamel layer, hypomineralization manifests in the form of opaque and crumbly spots without altered teeth contours. Fluorosis, for instance, is a rather frequently observed enamel defect that occurs due to increased fluoride intake. Pathogenetically, fluorosis is a form of enamel hypomineralization. EH and enamel hypomineralization may or may not affect one and the same tooth.
Avoiding environmental risk factors may not always be possible, but regular vaccination of mother and child may help to prevent certain infectious diseases. Healthy individuals rarely suffer from nutritional deficiencies and if nutrient absorption is known to be reduced due to pre-existing diseases, the corresponding supplements and/or medication should be taken. Only drugs approved for use during pregnancy or childhood should be used. Careful supervision of children reduces the incidence of trauma.
Children, adolescents, and adults should undergo regular dental check-ups. Visible dental defects, discoloration, sensitivity, and pain should prompt dental examination as soon as possible. Early diagnosis of EH defects prevents secondary dental diseases and facilitates treatment.
Proper oral hygiene should come naturally at all ages.
Enamel is the crown covering or external layer of the teeth. It covers the dentin layer and is produced by ameloblasts during amelogenesis, which takes place during fetal and early childhood tooth development. Healthy tooth formation occurs through different consecutive developmental stages. Only successful termination of a preceding stage guarantees physiological progress through subsequent phases. In this context, amelogenesis is dependent on dentinogenesis. Developmental enamel defects may be the result of abnormal amelogenesis, although dentinogenesis is not usually compromised. The most common developmental enamel defects are enamel hypoplasia (EH) and hypomineralization, particularly hypocalcification. EH results due to disturbed matrix formation while hypomineralization results from incomplete maturation.
EH may manifest in the form of pits and grooves of different shape and size or even total absence of enamel. The contour of the affected teeth may be altered. Malnutrition and disease may hinder amelogenesis for limited periods of time and in these cases, horizontal lines visible in the enamel layer mark conditions before and after developmental disturbance. Similarly, trauma may interfere with amelogenesis, but will not affect already formed enamel . In this context, the degree of EH is proportional to the severity of pathological conditions during amelogenesis. EH is most frequently observed in permanent teeth whose crown-covering enamel is formed during the first childhood years. However, if early amelogenesis is disturbed, EH may also occur in deciduous teeth. The disease may affect single or multiple teeth.
As has been indicated above, nutritional deficiencies and diseases are the most common triggers of EH. Infection, fever or exposure to certain drugs during pregnancy as well as the deficiency of vitamins A, C or D are possible causes of this disease. Premature birth has been related with EH . Trauma has been mentioned and may involve exposure to toxic substances.
Good oral hygiene practice is essential to avoid further tooth damage. Smaller enamel defects can simply be sealed, but teeth affected by extensive EH will need crown replacement to protect the underlying dental layers and to avoid sensitivity. If tooth damage is severe, the affected tooth may need to be extracted.
The outer layer of the upper part of the teeth, the crown, is called enamel. It is a hard, off-white substance covering the crown and protecting the tooth. Both milk as well as, permanent teeth possess enamel layers.
The process of enamel formation is called amelogenesis and starts during the second half of pregnancy, but does not terminate until well into the early years of childhood. If it is disturbed by any internal or external factor, the basic structure of the enamel layer, the matrix, cannot develop properly. Such a condition leads to defective enamel development and enamel hypoplasia (EH).
Infectious diseases such as chicken pox, measles, fever, nutritional deficiencies regarding vitamin A, C and D supply, hypocalcemia, certain medications, and trauma may interfere with enamel formation. As has been indicated above, amelogenesis is a process that takes very long to complete. The aforementioned factors may therefore, disturb enamel development at any time during late pregnancy and early childhood. Only teeth and crown regions that are currently in process of being covered with enamel will suffer the impact of the disruptive element.
Some forms of EH are inheritable. In these cases, all teeth, both deciduous and permanent ones, will be affected.
Single or multiple teeth may be affected; in the case of EH for genetic reasons, all teeth will show enamel defects. These teeth can be recognized due to their irregular, rough surface that is further characterized by pits and grooves as well as color changes. Opaque, yellowish or brown spots may be visible to the naked eye. EH patients often report increased sensitivity of affected teeth. Because the protective layer is defective or even missing, impaired enamel covering renders teeth more susceptible to other dental diseases.
EH will be diagnosed during routine dental exams. The dentist may ask for potential triggers that may have disturbed enamel formation during pregnancy or early childhood. In order to rule out secondary enamel attrition, one should confirm whether the patients grind their teeth or whether the teeth are mal-aligned.
Treatment depends on the extent of EH and possibly existing secondary tooth damage. Minor lesions may be sealed with desensitizing agents in order to reduce sensitivity. Bonding may be required to confer a protective layer to the respective area of the tooth. Similarly, a dental composite may be used to fill somewhat greater enamel defects. If these treatments are not sufficient to protect the tooth and to diminish sensitivity, artificial crowns will have to be employed. Only in extreme cases of EH or extensive tooth damage due to comorbidities, teeth will need to be extracted and replaced with implants or bridges.
Additionally, adequate oral hygiene and regular dental check-ups contribute to early detection of potential problems and greatly facilitate their treatment.