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Static occlusal
- relationships are seen when the jaws are closed in centric relation.
- The static occlusion can be efficiently observed in occluded study casts and seen directly in the oral cavity when the lips and cheeks are retracted.
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Normal (ideal) occlusion:
Ideal: all teeth in the maxillary arch are in maximum contact with all teeth in the mandibular arch in a definite pattern. Maxillary teeth slightly overlap mandibular teeth on the facial surfaces.
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Malocclusion:
any deviation from the physiologically acceptable relationship of the maxillary arch and/or teeth to the mandibular arch and/or teeth.
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Mesognathic.
Having slightly protruded jaws, which give the facial outline a relatively flat appearance (straight profile).
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Retrognathic.
Having a prominent maxilla and a mandible posterior to its normal relationship (convex profile).
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Prognathic:
Having a prominent, protruded mandible and normal (usually) maxilla (concave profile).
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Centric occlusion
- Posterior teeth are closed in a relaxed normal position.
- Anterior teeth have light contact.
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Who developed classifications for occlusion?
Dr. Edward Angle in 1890.
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Key to occlusion.
Mesiobuccal cusp of maxillary 1st molar.
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Types of facial profiles:
- Retrognathic - chin back (Sam's friend)
- Mesognathic - flat face look
- Prognathic - chin forward
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Crossbites:
- Posterior. Maxillary or mandibular posterior teeth are either facial or lingual to their normal position.
- This condition may occur bilaterally or unilaterally (as seen on the next slide). Anterior. Maxillary incisors are lingual to the mandibular incisors.
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Edge-to-edge bite:
incisal surfaces of maxillary teeth occlude with incisal surfaces of mandibular teeth instead of overlapping as in normal occlusion.
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End-to-end bite:
molars and premolars occlude cusp to cusp as viewed mesiodistally.
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Open bite:
- Lack of occlusal or incisal contact, posterior teeth in normal occlusion.
- The teeth cannot be brought together, and a space remains as a result of the arching of the line of occlusion.
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Overjet:
- Maxillary incisors are labial to the mandibular incisors.
- One way to measure the amount of overjet is to place the tip of a probe on the labial surface of the mandibular incisor and, holding it horizontally against the incisal edge of the maxillary tooth, read the distance in millimeters.
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Underjet:
- Maxillary teeth are lingual to mandibular teeth.
- Measurable horizontal distance between the labioincisal surfaces of the maxillary incisors and the linguoincisal surfaces of the mandibular incisors.
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Malposition of individual teeth.
- Labioversion - tooth that has assumed a position labial to normal
- Lingunoversio - position lingual to normal
- Buccoversion - position buccal to normal
- Supraversion - elongated above the line of occlusion
- Torsiversion - turned or rotated
- Infraversion - depressed below the line of occlusion, for example, primary tooth that is submerged or ankylosed.
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During the exam you noticed that your patient's maxillary incisors are lingual to the mandibular incisors; this is called_______.
Crossbite
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During your exam you noticed that the incisal edge of #8 & #9 occludes w/ the cervical 3rd of the facial surface of #24 & #25; this would be identified as ________.
deep overbite
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Occlusal contacts that are made outside of the normal range of function in occlusion are called _______.
parafunctional contacts.
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ANGLE Class I: NEUTROOCCLUSION
- Molar Relationship: According to Angle, the MB cusp of the maxillary 1st molar aligns with the B groove of the mandibular 1st molar.
- Canine Relationship: The maxillary canine occludes with the distal half of the mandibular canine and the mesial half of the mandibular first premolar
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Normal occlusion
- Molar Relationship: According to Angle, the MB cusp of the maxillary 1st molar aligns with the B groove of the mandibular 1st molar.
- Canine Relationship: The maxillary canine occludes with the distal half of the mandibular canine and the mesial half of the mandibular first premolar
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Class II or distocclusion
- Description - Mandibular teeth posterior to normal
- Facial profile. - Retrognathic; mandible appears retruded
- Molar relation: the buccal groove of the mandibular first permanent molar is distal to the MB cusp of the maxillary 1st permanent molar by at least the width of a premolar. When the distance is less than the width of a premolar, the relation should be classified as “tendency toward Class II.”
Canine relation: the distal surface of the mandibular canine is distal to the mesial surface of the maxillary canine by at least the width of a premolar. When the distance is less than the width of a premolar, the relation should be classified as “tendency toward Class II.”
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Class II, Division 1:
- Description: mandible is retruded and all maxillary incisors are protruded.
- General conditions that frequently occur :deep overbite, excessive overjet, abnormal muscle function (lips), short mandible, or short upper lip
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Class II, Division 2:
- Description: mandible is retruded, and one or more maxillary incisors are retruded.
- General conditions that frequently occur :
- maxillary lateral incisors protrude while both central incisors retrude, crowded maxillary anterior teeth, or deep overbite.
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Class III - Mesiocclusal
- Description - Mandibular teeth are anterior to maxillary
- Facial profile - Prognathic: mandible is prominent / protrudes
- Molar relation: the buccal groove of the mandibular 1st permanent molar is mesial to the MB cusp of the maxillary 1st permanent molar by at least the width of a premolar. When the distance is less than the width of a premolar, the relation should be classified as “tendency toward Class III.”
- Canine relation: the distal surface of the mandibular canine is mesial to the mesial surface of the maxillary canine by at least the width of a premolar. When the distance is less than the width of a premolar, the relation should be classified as “tendency toward Class III.”
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Types of trauma form occlusion:
- Primary trauma - excessive occlusal force is exerted on a tooth with normal bone support
- Secondary trauma - excessive occlusal force is exerted on a tooth with bone loss and inadequate alveolar bone support
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Effects of trauma from occlusion:
- Effects- attachment apparatus (periodontal ligament, cementum, and alveolar bone) has as its main purpose the maintenance of the tooth in the socket in a functional state
- Excessive forces - Circulatory disturbances, tissue destruction from crushing under pressure, bone resorption, and other pathologic processes
- Relation to inflammatory factors - Trauma from occlusion does not cause gingivitis, periodontitis, or pocket formation. In the presence of inflammatory disease, the existing periodontal destruction may be aggravated or promoted by trauma from occlusion.
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Recognition of signs of trauma from occlusion
- Clinical findings: - Tooth mobility / Fremitus / Sensitivity of teeth to pressure and/or percussion / Pathologic migration / Wear facets or atypical incisal or occlusal wear / Open contacts related to food impaction. Neuromuscular disturbances Temporomandibular joint symptoms.
- Radiographic findings - Triangulation = widened periodontal ligament spaces, particularly angular thickening / Vertical bone loss in localized areas / Root resorption / Furcation involvement / Thickened lamina dura /
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