deep overlap
Introduction
Deep cover Deep lamination is a misalignment caused by vertical dysplasia of the upper and lower arches and/or upper and lower jaws, ie the relative or absolute excessive development of the anterior teeth and alveolar height, or (and) posterior teeth and teeth The trough height is relatively or absolutely insufficient. According to the formation mechanism of deep lamination, it can be divided into deep lamination and deep laminar bone. Clinically, the upper anterior teeth can cover more than 1/3 of the crown of the anterior teeth; or the lower anterior teeth can be occluded more than 1/3 of the upper anterior teeth. The symptoms of the disease are upper or indirect incisors, the incisors are inclined at both sides, or the upper incisors are inwardly inclined and the cusps are inward, or all upper anterior teeth are introverted, and the anterior teeth cover less than 3 mm, sometimes 0 to 1 mm; Or the upper and lower anterior teeth are crowded, introverted, severely locked, and can bite the anterior or anterior teeth of the upper anterior teeth, causing acute and chronic periodontitis and causing alveolar bone absorption and loose teeth. basic knowledge The proportion of illness: 0.001% Susceptible people: no specific population Mode of infection: non-infectious Complications: facial atrophy
Cause
Deep lamination
Systemic factors (28%):
In childhood, the chronic diseases of the whole body are caused by jaw dysplasia, the posterior teeth are incomplete, the posterior alveolar height is insufficient, and the anterior teeth continue to erupt, the anterior alveolar height is too large, or the mandible rotates forward and upward.
Genetic or innate factors (19%):
The maxilla develops too much; the mandibular bone rotates forward and upward. The molars are severely dislocated to the dislocation, or the back teeth are excessively worn, reducing the vertical distance. The masticatory muscle tension is too large, and the inter-cuspal position (ICP) is tight when the muscle potential is large, and the alveolar bone growth is inhibited.
Other (8%):
Most deciduous teeth or the first permanent molars lose early, reducing the distance between the jaws, and lacking the stimulation of mastication, affecting the development of the jaw and alveolar. The congenital missing part of the mandible is incisive, the premature deciduous teeth are missing, and the anterior teeth are not exposed to normal contact and excessive eruption.
Pathogenesis
Mainly due to the improper matching of the anterior and posterior heights of the alveolar bone or the mandible, the coverage of the upper and lower anterior teeth is deepened, and there are three manifestations:
Type I is the anterior alveolar bone or jaw height is normal, and the posterior alveolar bone or jaw height is insufficient.
Type II is the anterior alveolar bone or jaw height is too large or the mandibular body is rotated upwards, and the height of the posterior alveolar bone is normal.
Type III is that the height of the anterior alveolar bone or jaw is too large and the height of the posterior alveolar bone or jaw is insufficient.
Prevention
Deep cover prevention
About 25% of the causes of occlusal malformation are genetic factors, and most of the rest are caused by acquired environment. According to the survey, about 80% of cases are preventable, so prevention is very important. Prevention should start from the fetal period, mother During pregnancy, nutrition should be strengthened to enhance the physical condition of the fetus. Infants should be breast-fed in the infancy, so that the mandible can be used for proper mandibular advancement, and the muscles of the tongue, lips and cheeks can be coordinated to develop the maxillofacial muscles. The period is a period of vigorous growth and development of children. Not only should we pay attention to the proper improvement of diet and nutrition, but also pay attention to properly improve the hardness of the food, so that the structure of the child is fully stimulated and the chewing function is improved. In addition, it is also important to keep the mouth clean.
Complication
Deep complication Complications facial lateral atrophy
Not only causes disturbance of occlusal relationship, but also can cause facial deformity, which seriously affects the patient's oral function and face.
Symptom
Deep laxity symptoms common symptoms traumatic mandibular posterior lip conversion
The upper central incisor is vertical or introverted, the incisors are inclined obliquely on both sides, or the upper incisors are inwardly inclined and the cusps are inward, or all upper anterior teeth are introverted, the anterior teeth cover less than 3 mm, sometimes 0 to 1 mm; or the upper and lower anterior teeth Crowded, introverted, severely occluded, can bite the anterior lingual or lower anterior labial sacral tissue, causing acute and chronic periodontitis, causing alveolar bone resorption, loose teeth, etc., posterior teeth are neutral or far In the middle, the lower lower arch is shortened, and the compensation curve and the sagittal curve of the deep upper arch are opposite arcs. The mandibular advancement and lateral movement are blocked, and the lower jaw can only be closed. The hinged movement, such as the side-to-side movement, is also due to the fact that the distal side of the maxillary canine has been ground into a groove to achieve rearward; functional mandibular retraction, lip muscle and masticatory muscle tension are normal or too large, When the ICP is bitten, the muscle potentials are large, and the shape of the facial jaw is still well developed. It is generally in the shape of a face, the lower third of the face is shorter, the mandibular angle is prominent, and the mandibular plane angle is a low angle type. The shape is the lower lip eversion, forming a horizontal deep wrinkle, the crotch protrudes forward, and the nose rises outward. Lip shortening.
Examine
Deep cover inspection
Clinical physical examination: the upper central incisor is vertical or introverted, the incisors are inclined obliquely on both sides, or the upper incisors are inwardly inclined and the cusps are inward, or all upper anterior teeth are introverted, and the anterior teeth cover less than 3 mm, sometimes 0 to 1 mm; Or the upper and lower anterior teeth are crowded and introverted, showing severe atresia. It can be seen that the bite of the upper anterior lingual or the lower anterior labial sacral tissue causes periodontitis and causes alveolar bone resorption, loose teeth, etc., and the posterior teeth are neutral. Or in the far center, the lower lower arch is shortened.
Laboratory examination: X-ray examination of the jaw can clarify the specific deformity and severity.
Diagnosis
Deep lamination diagnosis
diagnosis
Issue it to 3 degrees according to the degree of coverage:
I degree: the upper anterior teeth cover more than 1/3 to 1/2 of the anterior crown; or the lower anterior teeth are 1/3 or more to 1/2 of the upper anterior lingual side.
II degree: the upper anterior teeth cover more than 1/2 to 2/3 of the anterior crown length; or the lower anterior teeth are occluded in the upper anterior lingual side cut more than 1/2 to 2/3 (such as the tongue bulge) .
III degree: the upper anterior crown completely covers the lower anterior crown, even biting on the lower anterior labial sacral tissue; or the lower anterior teeth are occluded on the anterior lingual or sacral mucosa, thus causing traumatic gingivitis or Mucosal damage.
Specific diagnosis can be combined with X-ray cephalometric analysis.
Disease identification
Deep overjet: Deep anterior teeth coverage refers to the horizontal distance from the upper anterior cutting edge to the lower anterior labial surface exceeding 3 mm. Deep anterior teeth coverage is a common symptom of malocclusion.
Scissors bite: Some people call it a strabismus deformity, which is a misalignment of the posterior teeth. According to the positional relationship of the buccal and lingual parts of the upper and lower teeth, the lock can be divided into positive and negative locks in clinical practice. Positive locking refers to the buccal side of the tip of the maxillary posterior teeth located on the buccal side of the cheeks of the cheeks of the lower jaw, and there is no occlusal contact on the face. It is more common in clinical practice; the anti-locking occlusion refers to the cheek slope and the lower cheek of the upper posterior teeth. The lingual surface of the tongue of the posterior teeth is bitten, and there is no occlusal contact on the face. It is rare in clinical practice. Locking can occur on one side of the dental arch, or on both sides of the dental arch; it is more common on the side of the dental arch, and less common on both sides of the dental arch; permanent teeth are more common and milky. Teeth are less common. Most commonly found in the upper and lower jaw second molars, the locking of the premolar area is also more common.
Open bite: refers to the phenomenon that the upper and lower jaw teeth are in occlusal contact in the vertical direction when the median teeth are in position. Opening and closing can occur in the deciduous period, the dentition period and the permanent period. The clinical stage is the most common in the permanent dentition. The main mechanism is the vertical development of the upper and lower arch and jaw.
Posterior crossbite: often caused by stenosis of the maxillary arch or lingual tilt of the maxillary posterior teeth. A small number of patients are caused by the excessive width of the mandibular arch or the cheek side of the lower jaw. Clinically, the posterior teeth can occur on one side or on both sides; it can be expressed as individual posterior teeth, or it can be a majority of posterior teeth.
