Congenital Anomalies are a broad category of health conditions that are present at birth and is a deviation from normal anatomic growth, development, or function. The congenital anomaly may have developed in utero or may have genetic origins.
Anodontia is defined as the failure of teeth to form, completely or partially.
Ectodermal Dysplasia:
In congenital ectodermal dysplasia, teeth are absent or conical in appearance so that from childhood, partial dentures are needed.
Congenital ectodermal dysplasia is the result of an hereditary fault affecting the stage of initiation of various specialized ectodermal structures. It is characterized by one or all of the following:
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Anodontia – partial or total
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Absence of sweat or sebaceous glands. The skin is smooth, atrophic and wrinkled. The absence of sweat glands makes the child extremely susceptible to heat prostration since heat regulation by sweating is absent.
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Absence of hair. Lanugo (fetal) hair only, present on scalp. Scant eyebrows and eyelashes and wrinkled skin give an aged appearance to the face.
Fingernails and toenails may also be dystrophic. There is also deficiency in the lacrimal and salivary glands. The iris may be affected.
The defect affects males more frequently than females and is transmitted genetically through the mother. The growth of the maxillary and mandibular bases is entirely normal. Prostheses should be constructed as soon as the child is able to cooperate, usually between 3 to 6 years of age. These children manage the prosthesis remarkably well in spite of the absence of an alveolar process due to the absence of teeth. Dentures produce a marked psychologic improvement in both the child and his parents and give the face a younger appearance. Since the denture bases increase only in length and not in width, the prostheses need to be replaced only at the following age periods to simulate changes in the natural dentition and to accommodate for increased length of the denture base: at 3-6 years (mixed dentition), at 15 years (young permanent dentition), and in adulthood, to simulate the older, worn dentition.1
More about Ectodermal Dysplasia.
Dentinogenesis Imperfecta:
Hereditary Opalescent Dentin or Dentinogenesis Imperfecta, an autosomal dominant disorder produces abnormal dentin that is dull and bluish brown or opalescent and does not cushion the overlying enamel adequately. Such teeth cannot withstand occlusal or biting stresses and rapidly become worn. Congenitally narrow lateral incisors, often referred to as “peg shaped” laterals, are not associated with systemic disease.
Dentinogenesis Imperfecta is the result of a dominant genetic defect which affects both the deciduous and permanent dentitions. The teeth appear a gray, amber, or brown translucent color and undergo a characteristically rapid and severe attrition as soon as they appear within the oral cavity. The third characteristic is the absence of pulp chambers and usually also, an absence of pulp canals.
The enamel appears to be normal both histologically and chemically but tends to chip away from the dentin and wears away with extraordinary rapidity. The dentino-enamel junctions are smooth and non-scalloped.
The dentin is imperfectly formed (Dentinogenesis Imperfecta). It is atubular, fibrous and highly irregular. A thin peripheral layer (the mantle dentin) is normally formed.
Pulp. The fibrous dentin is laid down continuously so that the pulpal outline as seen in the x-rays is abnormal even in the young child. The pulp chamber is soon obliterated and the pulp canal remains only as a thin slit or is also obliterated. In spite of the fibrous dentin and absence of pulp tissue, the sensitivity of these teeth varies from normal to decreased sensation.
The rapid attrition of these teeth soon results in a closed bite. Crowns should be placed on the deciduous and permanent molars as soon as they appear into the oral cavity. Even brief delays result in wearing of the enamel crown to the gingival line. Procera crowns should be placed on the anterior teeth as soon as the self-conscious child requests them. Preparations of the teeth for crowns is minimal due to the rapid wear.
Dentinogenesis Imperfecta may occur alone or may be associated with another mesodermal defect, osteogenesis imperfecta (brittle bone disease) and blue sclera. When the triad occurs together, the defects tend to be very severe and the condition is termed Congenital Mesodermal Dysplasia. In view of this possible association, a history of bone fractures should always be sought in children with hereditary opalescent dentin.2
References:
1) Sarnat, B.G., Brodie, A.G., and Kubacki, W.H.: Fourteen-year Report of Facial Growth in a Case of Complete Anodontia with Ectodermal Dysplasia. Am. J. Dis. Child. 86: 162-169, August 1953.
2) Roberts, E. and Schour, I.: Hereditary Opalescent Dentin (Dentinogenesis Imperfecta). AM. J. Orthod. and Oral Surg. 25:267-276, March 1939.
