Extraoral Landmarks in Dentistry

The inter-pupillary line is an imaginary line between the two pupils of the eyes, used to orient the anterior occlusal plane of artificial teeth.

The ala-tragus line is an imaginary line from the ala of the nose to the tragus of the ear, used to orient the posterior occlusal plane of artificial teeth.

The canthus-tragus line runs from the outer canthus of the eye to the tragus of the ear and is used for the arbitrary location of the condyles.

<p>The nasio-labial sulcus is a depression from the ala of the nose to the corner of the mouth, becoming deeper with age due to tissue changes.</p> Signup and view all the answers

<p>The vermillion border is the transition between the lip mucous membrane and facial skin, which loses support from the orbicularis oris after tooth loss.</p> Signup and view all the answers

<p>The labial tubercle is a swelling in the center of the upper lip's vermillion border that drops inward due to loss of support after tooth resorption.</p> Signup and view all the answers

<p>Two extraoral landmarks are the inter-pupillary line and the ala-tragus line.</p> Signup and view all the answers

<p>The angle of the mouth, or commissure, is important for esthetics and function of dentures, as it affects lip closure and facial contour.</p> Signup and view all the answers

<p>The curvature indicates the maxillo-mandibular relationship, with a gentle curve representing a normal ridge relationship.</p> Signup and view all the answers

<p>Angle Class II is characterized by a retruded mandibular position, resulting in the mento-labial sulcus forming an acute angle.</p> Signup and view all the answers

<p>The philtrum is a diamond-shaped area at the center of the upper lip that can be distorted by loss of teeth and alveolar bone resorption.</p> Signup and view all the answers

<p>Angular cheilitis is inflammation and drooping of saliva from the angle of the mouth, caused by prolonged edentulism or vitamin B12 deficiency.</p> Signup and view all the answers

<p>The modiolus is the point where facial muscle fibers meet, and it is significant because its position changes after tooth loss, affecting denture fit.</p> Signup and view all the answers

<p>A stress bearing area is a region that can withstand forces from the denture base without causing tissue ulceration or bone resorption.</p> Signup and view all the answers

<p>Proper denture construction with correct vertical dimension and positioning of anterior teeth will support the angle of the mouth.</p> Signup and view all the answers

<p>After tooth loss and alveolar bone resorption, the modiolus drops inward, resulting in a characteristic appearance of edentulism.</p> Signup and view all the answers

<p>The criteria are that it must be relatively horizontal, consist of compact bone type, and have thick mucosa.</p> Signup and view all the answers

<p>A relief area is a sensitive elevated region that cannot withstand pressure, necessitating a space in the denture base to reduce stress.</p> Signup and view all the answers

<p>The residual alveolar ridge serves as the primary stress-bearing area in the upper arch, covered with dense fibrous connective tissue that is favorable for support.</p> Signup and view all the answers

<p>The maxillary tuberosity is a bony prominence that helps retain and support the maxillary denture.</p> Signup and view all the answers

<p>The median palatine raphe is an area of firm mucous membrane that lacks resiliency, and stress should not be applied here to avoid denture rocking.</p> Signup and view all the answers

<p>After tooth extraction, the incisive papilla migrates to the crest of the ridge due to alveolar bone resorption.</p> Signup and view all the answers

<p>Relief of the incisive papilla is necessary to avoid interference with the blood and nerve supply, which can cause sensations of burning.</p> Signup and view all the answers

<p>Some supporting structures include the residual alveolar ridge, maxillary tuberosity, median palatine raphe, incisive papilla, palatine rugae, torus palatinus, and fovea palatinae.</p> Signup and view all the answers

<p>A perpendicular line drawn posterior to the center of the incisive papilla passes through the tip of the maxillary canines.</p> Signup and view all the answers

<p>Palatine rugae assist the tongue in forming a seal for linguopalatal sounds, such as the 'S' sound.</p> Signup and view all the answers

<p>The torus palatinus may necessitate relief in the denture base if small or surgical removal if large to prevent irritation.</p> Signup and view all the answers

<p>Fovea palatinae are small pits located just posterior to the junction of the hard and soft palate.</p> Signup and view all the answers

<p>The residual alveolar ridge is formed of cancellous bone and is unsuitable for bearing stresses.</p> Signup and view all the answers

<p>The crest of the ridge is the highest part of the residual alveolar ridge.</p> Signup and view all the answers

<p>A torus palatinus can cause tissue irritation and ulceration when pressure is applied by a maxillary denture.</p> Signup and view all the answers

<p>The external oblique ridge and the buccal shelf of bone are two supporting structures of the mandibular arch.</p> Signup and view all the answers

<p>The external oblique ridge acts to prevent denture displacement by the masseter muscle, as lower dentures should cover but not extend beyond it.</p> Signup and view all the answers

<p>The buccal shelf is nearly perpendicular to vertical masticatory forces and consists of dense compact bone, making it ideal for support.</p> Signup and view all the answers

<p>The mental foramen is located on the buccal surface of the mandible between the first and second premolars, and relief is required to avoid lower lip numbness.</p> Signup and view all the answers

<p>The retromolar pad contains mucous glands and muscle fibers, and it provides a shock-absorbent cushion, contributing to denture support and stability.</p> Signup and view all the answers

<p>The pterygomandibular raphe may cause dislodgement of dentures as it stretches during mouth opening, affecting stability.</p> Signup and view all the answers

<p>A torus mandibularis may necessitate relief in the denture base to avoid mucosal impingement if it is covered with thin mucosa.</p> Signup and view all the answers

<p>The retromolar pad helps cushion the denture, maintain the occlusal plane, and assists in arranging mandibular posterior teeth.</p> Signup and view all the answers

<p>If the denture base extends beyond the external oblique ridge, it may lead to denture displacement due to the action of the masseter muscle.</p> Signup and view all the answers