Premature eruption, natal, and neonatal teeth
Teeth erupted at birth (natal teeth) or which erupt within the first 30 days of life (neonatal teeth) are uncommon, occurring in about 1 in 3000 live births in most reported series. In about 80 per cent of cases the mandibular incisors, usually one or both central incisors, are involved. They are thought to arise from normal tooth germs developing in a superficial position in the jaw with subsequent premature eruption. Coronal enamel and dentine formation is normal for the chronological age of the tooth, but because of the premature eruption the enamel may be hypoplastic. However, there is usually a virtual absence of root formation and any radicular dentine or cementum that forms is generally irregular in structure due to the mobility of the tooth in the jaw (Such teeth may be lost spontaneously or have to be extracted if there is a risk of dislocation and inhalation, or if they interfere with feeding.
Premature eruption of other deciduous or permanent teeth is rare and may be related to local factors such as a superficial location of a tooth germ or early shedding of deciduous teeth. Generalized early eruption of the permanent dentition may also be seen in children with endocrine abnormalities associated with an excess secretion of growth hormone or with hyperthyroidism.
Retarded eruption
Endocrinopathies (for example hypothyroidism), prematurity, nutritional deficiencies, and chromosome abnormalities, such as Down syndrome, may very occasionally be associated with retarded eruption of either the deciduous and/or permanent dentition. Idiopathic migration, traumatic displacement of tooth germs, or abnormally large crowns may also be associated with retarded eruption. Delayed eruption and multiple, impacted supernumerary teeth are also a feature of cleidocranial dysplasia
Premature loss
This is usually the result of either dental caries and its sequelae, or chronic periodontal disease. Occasionally, premature loss of teeth is more specifically associated with diseases such as hypophosphatasia, hereditary palmar-plantar hyperkeratosis, and other causes of periodontitis in systemic disease.
Persistence of deciduous teeth
This occurs when deciduous teeth are not shed at the expected time, and is usually associated with the failure of eruption of the permanent successor because it is missing or displaced. Persistence of the entire deciduous dentition is uncommon and usually has a systemic background, such as cleidocranial dysplasia when eruption of permanent teeth is impeded.
Impaction of teeth
An impacted tooth is one which remains unerupted, or only partly erupted, in the jaw beyond the time when it should normally be fully erupted. One or several teeth may be affected and the condition may be symmetrical. It is rarely seen in the primary dentition. In the permanent dentition the teeth most frequently involved are third molars, mandibular premolars, and maxillary canines. Local causes for impaction include abnormal position of the tooth germ, lack of space for the teeth in the jaws, supernumerary teeth, cysts, and tumours. As previously mentioned, cleidocranial dysplasia is almost always associated with multiple impacted teeth. Possible complications of impaction include resorption of the impacted tooth or adjacent erupted teeth, and the development of dentigerous cysts and odontogenic tumours.
Reimpaction of teeth
This term describes the situation in which a previously erupted tooth becomes submerged in the tissues. Alternative terms for the disorder are infraocclusion and submerged teeth. The deciduous second molar is most commonly affected and reimpaction occurs twice as frequently in the mandible than in the maxilla.The condition is associated with deficient development of the alveolar process around the reimpacted tooth which may, on rare occasions, become completely covered by oral mucosa. The roots of the tooth are usually partly resorbed and ankylosed to the bone. The cause is not known, but it is likely that the root first becomes ankylosed and that this is followed by lack of growth of the alveolar process. As the neighbouring teeth continue to move occlusally they tilt over the ankylosed tooth, causing reimpaction.
Endocrinopathies (for example hypothyroidism), prematurity, nutritional deficiencies, and chromosome abnormalities, such as Down syndrome, may very occasionally be associated with retarded eruption of either the deciduous and/or permanent dentition. Idiopathic migration, traumatic displacement of tooth germs, or abnormally large crowns may also be associated with retarded eruption. Delayed eruption and multiple, impacted supernumerary teeth are also a feature of cleidocranial dysplasia
Premature loss
This is usually the result of either dental caries and its sequelae, or chronic periodontal disease. Occasionally, premature loss of teeth is more specifically associated with diseases such as hypophosphatasia, hereditary palmar-plantar hyperkeratosis, and other causes of periodontitis in systemic disease.
Persistence of deciduous teeth
This occurs when deciduous teeth are not shed at the expected time, and is usually associated with the failure of eruption of the permanent successor because it is missing or displaced. Persistence of the entire deciduous dentition is uncommon and usually has a systemic background, such as cleidocranial dysplasia when eruption of permanent teeth is impeded.
Impaction of teeth
An impacted tooth is one which remains unerupted, or only partly erupted, in the jaw beyond the time when it should normally be fully erupted. One or several teeth may be affected and the condition may be symmetrical. It is rarely seen in the primary dentition. In the permanent dentition the teeth most frequently involved are third molars, mandibular premolars, and maxillary canines. Local causes for impaction include abnormal position of the tooth germ, lack of space for the teeth in the jaws, supernumerary teeth, cysts, and tumours. As previously mentioned, cleidocranial dysplasia is almost always associated with multiple impacted teeth. Possible complications of impaction include resorption of the impacted tooth or adjacent erupted teeth, and the development of dentigerous cysts and odontogenic tumours.
Reimpaction of teeth
This term describes the situation in which a previously erupted tooth becomes submerged in the tissues. Alternative terms for the disorder are infraocclusion and submerged teeth. The deciduous second molar is most commonly affected and reimpaction occurs twice as frequently in the mandible than in the maxilla.The condition is associated with deficient development of the alveolar process around the reimpacted tooth which may, on rare occasions, become completely covered by oral mucosa. The roots of the tooth are usually partly resorbed and ankylosed to the bone. The cause is not known, but it is likely that the root first becomes ankylosed and that this is followed by lack of growth of the alveolar process. As the neighbouring teeth continue to move occlusally they tilt over the ankylosed tooth, causing reimpaction.
Non-bacterial loss of tooth substance
Introduction
Although it is convenient to discuss attrition, abrasion, and erosion separately, in many patients tooth wear involves elements of all three. For this reason terms such as 'tooth wear with a major component of attrition' are usually preferred as clinical diagnoses.
Key points - Non-bacterial loss of tooth substance
· tooth wear
- attrition
- abrasion
- erosion
· resorption
- internal
- external
Attrition
Introduction
Although it is convenient to discuss attrition, abrasion, and erosion separately, in many patients tooth wear involves elements of all three. For this reason terms such as 'tooth wear with a major component of attrition' are usually preferred as clinical diagnoses.
Key points - Non-bacterial loss of tooth substance
· tooth wear
- attrition
- abrasion
- erosion
· resorption
- internal
- external
Attrition
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