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Questions and Answers
What occurs to the orbicularis oris muscle following tooth loss?
In Angle Class II, how does the mento-labial sulcus typically appear?
What anatomical feature is located between the upper lip and the base of the nose?
What happens to the modiolus after tooth loss?
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What is the term for the portion of the alveolar process that remains after teeth are extracted?
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Which structure is considered the primary stress-bearing area in the upper jaw?
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How does the absence of teeth affect the philtrum's appearance?
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What is the characteristic angle of the mento-labial sulcus in Angle Class I?
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What is the purpose of the inter-pupillary line in denture construction?
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Which line is used to establish the posterior occlusal plane of a denture?
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What anatomical feature does the naso-labial sulcus describe?
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What role does the vermillion border play in denture construction?
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Which of the following is NOT an extraoral landmark used in prosthetics?
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What is a common result of aging and loss of teeth in relation to the naso-labial sulcus?
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Which landmark is arbitrary for locating the position of the condyles?
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Why is knowledge of oral anatomy critical during denture construction?
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Study Notes
Extraoral Landmarks of Prosthetic Importance
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Inter-pupillary line: Imaginary line connecting the pupils when looking straight ahead. Used for orienting the maxillary anterior occlusal plane.
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Ala-tragus line: Imaginary line from the nose's inferior border (ala) to the ear's tragus. Establishes the posterior occlusal plane of artificial teeth.
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Canthus-tragus line: Line from the eye's outer canthus to the ear's tragus. Used to locate the condyles.
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Naso-labial sulcus: Depression from the nose's ala downward and laterally. Deepens with age and tooth loss. Denture construction aims to restore its contour.
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Vermillion border: Transitional epithelium between lip and skin. Tooth loss and bone resorption affect its appearance, reducing its prominence.
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Mento-labial sulcus: Horizontal depression between lower lip and chin. Its curvature reflects maxillo-mandibular relationship and overclosure.
- Angle class I: Normal ridge relationship, gentle curvature.
- Angle class II: Retruded mandible, acute angle with lip folding towards chin.
- Angle class III: Protruded maxilla, almost 180° angle.
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Philtrum: Diamond-shaped area between upper lip and nose. Tooth loss distorts its shape. Dentures can restore its contour.
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Modiolus: Confluence of buccinator and facial muscles near the mouth's angle. Droops with tooth loss, contributing to the sunken appearance of edentulous individuals.
Intraoral Landmarks of Prosthetic Importance - Maxilla
- Residual ridge: Remaining alveolar process after tooth extraction. Resorption reduces its size. The highest continuous surface is the ridge crest. Serves as the primary stress bearing area in the upper jaw.
- Maxillary tuberosity: Rounded bulge behind the last molar. Important for denture extension and stability.
- Hamular notch: Concave notch on the posterior border of the maxillary tuberosity. Used as a posterior denture border landmark.
- Pterygomaxillary notch: Narrow space between the maxillary tuberosity and the pterygoid process. Used for denture border placement.
- Incisive papilla: Small, rounded projection on the palate, anterior to the incisive foramen, marking the location of the incisive foramen.
- Incisive foramen: Opening in the palate, just behind the central incisors. Important for denture design as it houses nerves and vessels that need to be avoided.
- Maxillary rugae: Irregular ridges on the hard palate. Act as a guide for denture fitting.
- Palatine raphe: Ridge of tissue that runs down the midline of the hard palate. A landmark used for denture positioning.
- Hard palate: Bony roof of the mouth, covered by mucosa. Provides support for the denture.
- Soft palate: Posterior part of the palate, composed of muscle and soft tissue. Important for denture extension and retention.
- Vibrating line: Line on the soft palate that marks the transition between the fixed and movable parts. Determines the denture's posterior extension.
- Fossa palatina: Depression on the posterior hard palate. Used as a reference point for denture border placement.
- Posterior palatine foramina: Small openings on the hard palate, posterior to the rugae. Important for denture design as they house vessels and nerves.
- Maxillary alveolus: Socket where the tooth roots were located. Resorption after tooth extraction reduces its size.
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Description
Test your knowledge on the extraoral landmarks crucial for prosthetic dentistry. This quiz covers key lines and anatomical features important for denture construction and alignment. Understand their significance in creating functional and aesthetic dental prosthetics.
