dental abnormalities
Introduction
Introduction The development of human teeth is a complex and lengthy process. In this long process, various unfavorable factors inside and outside the body can cause different types of developmental abnormalities in different stages of tooth development, such as abnormal teeth eruption, abnormal number, abnormal morphology and abnormal tooth structure.
Cause
Cause
The cause of abnormal teeth
The development of teeth is divided into three compensations: occurrence, calcification and eruption. The deciduous tooth germ develops from the second month of the embryo, and the oral mucosal epithelium rapidly proliferates in the corresponding part of the tooth germ. Locally thickened and protruded into the middle ovule to form a dental plate. Deep cell proliferation in the dentate plate, forming 10 spherical superior bulging in the upper and lower jaws, called the tooth bud. At 4 months of the embryo, in the distal direction of the second deciduous tooth germ, the dental plate extends distally and gradually forms the first permanent molar tooth germ. At 5-6 months of the embryo, at the deep side of the lingual side of the deciduous tooth, the end of the dental plate proliferates to form a permanent tooth bud, which becomes a permanent tooth tooth germ instead of the deciduous tooth. Then the deep cells of the dentate further proliferate to form a glaze, and gradually form enamel through the bud stage, the cap stage, and the bell stage. The opposite mesodermal tissue under the dental plate proliferates to form a dental papilla, and dentin cells are formed under the enamel to form dentin. It takes a long time for the teeth to develop, calcify, erupt, and until the roots are completely formed. For example, the formation of permanent incisors takes about ten years. During the long-term development of teeth, systemic diseases, malnutrition, improper medication and local infections of mothers and children can affect the normal development, calcification and eruption of teeth.
(A) enamel hypoplasia: during tooth development, due to systemic disease, nutritional disorders or severe apical apical infection, can lead to abnormal enamel structure. When vitamin A is deficient, the glaze cannot differentiate into high columnar cells and become squamous cells, resulting in enamel hypoplasia. When vitamin C is deficient, odontoblasts are degenerated and cannot form normal dentin. In severe cases, dentin development stops. Denaturation of odontoblasts can affect the normal development of enamel. When vitamin D is severely deficient, the deposition of calcium salt in bone and tooth tissue is slow or even stopped, so that the formed enamel matrix cannot be timely mineralized, can not maintain its shape and collapse, resulting in the formation of depressions and minerals on the enamel surface. Poor.
(2) Dental fluorosis: It is a special type of enamel hypoplasia caused by excessive intake of human body during the development of teeth. The mechanism is not fully understood. However, the following understandings are made: 1 When the concentration of fluorine is increased, the activity of alkaline phosphatase can be inhibited. Alkaline phosphatase can hydrolyze a variety of phosphates to provide sufficient inorganic phosphorus as a raw material for bone salt formation. The result is incomplete interstitial mineralization, resulting in enamel dysplasia. 2 high fluoride can cause swelling of the endoplasmic reticulum of the enamel cells, and glaze matrix synthesis disorders. 3 Excessive fluorine is combined with enamel and exists as fluoroapatite. Excessive fluoroapatite causes degeneration and stripping of enamel cells, resulting in enamel hypoplasia. Excessive fluoroapatite replaces hydroxyapatite, changing the normal calcification process of enamel.
(C) Tetracycline teeth: Tetracycline has an affinity with calcium ions, and the two combine to form a stable tetracycline calcium complex. When tetracyclines are continuously taken during tooth development and mineralization, tetracycline molecules can be tightly bound to the hydroxyapatite crystals of the teeth to form a tetracycline calcium orthophosphate complex, which can discolor the teeth and severely inhibit the hard tissue of the teeth. The deposition of chemical substances and collagen synthesis of dentin cells affect the development of enamel and dentin. Tetracycline can also cause deciduous coloration in the mother through the placenta. The degree of tetracycline staining and dentin calcification is related to the color, drug dosage and age of the tetracycline drug itself. Tetracycline-induced coloration is more pronounced than oxytetracycline and chlortetracycline. The time and dose of the drug are directly proportional to the degree of coloration, and a large dose in a short period of time is more effective than a total dose equivalent to a long-term service. Tetracycline in the dentin, the degree of dentin coloration is different due to the depth of the binding site. When the coloring band is closer to the enamel dentin, the coloring is easier. Therefore, when the outer layer of dentin is formed in the early stage of the baby, the effect of the drug is affected. maximum. Once the teeth are colored, they are permanent. After the formation of crowns and calcification is complete (usually taking tetracyclines for people around 7 years old, it is not obvious to the teeth.
(4) Congenital syphilis teeth: The most serious period of syphilis damage to tissues is at the end of the embryo and the first month after birth, so syphilis is more common. On this side, it is in the stage of tooth germ differentiation, inflammation affects the glaze, damages the enamel cells, and some enamel is stopped. In addition, it can also cause mineralization disorders of dentin. The dentin is increased in the early stage, causing the dentin to collapse and form a half-moon shape damage.
(5) Fusion teeth: fusion due to stress. If this pressure occurs before the two teeth are calcified, the crown is fused. If it occurs after the development of the crown, the root is merged into one, and the crown is divided into two teeth.
(1) abnormal teeth caused by systemic diseases
1. Severe nutritional disorders: Vitamins A, C, D and calcium. Phosphorus deficiency can affect the secretion of enamel matrix and mineralization by enamel cells, resulting in enamel surface depression and poor mineralization.
2. Endocrine dysfunction: When the parathyroid function is reduced, there is a clinical manifestation of hand and foot spasm, and its teeth may also have developmental defects.
3. Infectious diseases: Children with chickenpox and scarlet fever can cause obstacles in the development of enamel cells. Pregnant women suffering from rubella, toxemia, etc. may also cause enamel hypoplasia in the fetus during this period.
4. Digestive system diseases: Children with habitual constipation, diarrhea, vomiting, dyspepsia and lack of nutrition can also be the cause of enamel hypoplasia.
5. Congenital syphilis: Causes abnormal tooth morphology.
6. Chronic fluorosis: Fading plaques that damage enamel-developing tooth germs occur.
7. Excessive use of tetracyclines: Yellowing teeth can cause "tetracycline teeth".
(2) Dental abnormalities caused by local diseases
1. Root infection and trauma of deciduous teeth: affect the development of the permanent tooth germ below, resulting in abnormal tooth structure, morphology and eruption.
2. Rickets, periodontal disease: deciduous teeth can cause abnormal eruption of permanent teeth. Permanent dental caries and periodontal disease can cause tooth corrosion. Loose, shedding, causing missing teeth, even toothless deformities.
3. Inflammation of the gums, hypertrophy: causing the teeth to erupt too late, ectopic.
4. Local radiation of the oral cavity: It can decalcify and soften the teeth, prone to extensive caries, and progress rapidly, resulting in the loss of multiple teeth.
(3) Genetic factors: hereditary dentin dysplasia, congenital missing teeth and late mouth gingeration have genetic factors.
Examine
an examination
Related inspection
Oral endoscopic oral X-ray examination of pulp electrical activity determination of pulp temperature test (cold fever diagnosis)
Examination of abnormal teeth
(1) medical history
Ask the child about his previous medical history and medication history, whether he took tetracyclines, the time and dosage. Whether living in a high fluoride area, local morbidity. Have a history of acute infection of the maxillofacial region. Whether there is systemic disease and performance.
(2) Partial inspection
1. Looking around: Observe the number, shape, color and arrangement of the teeth. Whether there is white color, light yellow, yellow brown. Ink immersion, dark brown. Whether the damaged part is at the tip of the crown or the neck is linear, dotted or full crown discolored.
2. Probing: Use a sharp probe to probe the defect area and understand the hardness of the tooth. The dentin is soft and the caves are mostly rickets, such as hard dentin, rough tooth surface, and uneven enamel dysplasia.
(three) systemic examination
For the abnormal shape of teeth such as half-moon incisors, mulberry-shaped molars and bud-shaped molars, a systemic examination is required, and changes in other organs of the body can be established to establish a diagnosis.
(4) Laboratory inspection
Such as Kang's, Fahrenheit reaction test, determination of fluorine content and ultraviolet light to check the tetracycline staining band of the teeth.
(5) X-ray examination
X-ray examination is required for late teeth, abnormal roots, fused twins, multiple teeth, ambushed teeth, and dental caries. Patients with suspected congenital syphilis should be aware of the bones in other parts, often requiring X-ray examination.
Diagnosis
Differential diagnosis
Symptoms of abnormal teeth
1. Abnormal teeth eruption: more common in permanent teeth, because permanent teeth are more affected by deciduous teeth diseases, such as deciduous teeth retention or early loss, trauma, etc. Common eruption abnormalities: early teeth, eruption and ectopic eruption.
2. Insufficient number of teeth: The number of normal human teeth is 20 deciduous teeth and 28-32 permanent teeth. The abnormal number of teeth is due to insufficient or excessive number of teeth. The number of teeth is insufficient, also known as congenital missing teeth, and there are individual missing teeth. Partially missing teeth and full mouth missing teeth.
3. Excessive number of teeth: The number of normal human teeth is 20 deciduous teeth and 28-32 permanent teeth. The abnormal number of teeth is characterized by insufficient or excessive number of teeth. Commonly, there are many teeth (also called extra teeth) and dental tumors.
4. Abnormal tooth structure: refers to the abnormal development of teeth caused by various obstacles during tooth development or matrix calcification during tooth development, and leaves permanent defects or traces on the tooth tissue. Common ones are: Enamel dysplasia, dentine hypoplasia, dental fluorosis and tetracycline staining teeth.
5. Abnormal dental morphology: the shape and size of the teeth, like the physical appearance, affected by genetic factors, the mode of action, is still unclear. A few under the influence of environmental factors, such as mechanical pressure, can also cause tooth morphology Variations. Common tooth morphology abnormalities are as follows: malformed cusps, malformed sockets, deformed teeth, deformed teeth, curved teeth, etc.
