Anatomy of the Denture Bearing Areas PDF

Anatomy of the denture bearing areas Dr. Azize Demir https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/  The anatomy of the edentulous ridge in the maxilla and mandible is very important f...

Anatomy of the denture bearing areas Dr. Azize Demir https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/  The anatomy of the edentulous ridge in the maxilla and mandible is very important for the design of a complete denture. Objective in fabrication of a complete denture is to provide a prosthesis that restores lost teeth and associated structures functionally, anatomically and aesthetically as much as possible with preservation of underlying structures and the knowledge landmarks help us in achieving our objective. https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/  The landmarks of an edentulous jaw are grouped into limiting structures, supporting structures and relief area. https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/  Limiting structures These are the sites that will guide us in having an optimum extension of the denture so as to engage maximum surface area without encroaching upon the muscle actions. Encroaching upon these structures will lead to dislodgement of the denture and/or soreness of the area while failure to cover the areas up to the limiting structure will imply decreased retention, stability and support. https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/  Supporting structures / Stress-bearing areas Supporting structures are the load bearing areas. The denture should be designed such that most of the load is concentrated on these areas. Support is the resistance to the displacement towards the basal tissue or underlying structures. https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/  Relief area Relief areas are areas where they are either resorb under constant load, having fragile structures within or covered by thin mucosa which can be easily traumatized. It should be designed in such away that the masticatory load is not concentrated over these area. https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/  Anatomical Landmarks – MAXILLA https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/  LIMITING STRUCTURES Labial & buccal frenum Labial & buccal vestibule (sulcus) Hamular notch Posterior palatal seal area (post-dam) https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/   Labial & buccal frenum Fibrous band covered by mucous membrane. Labial frenum extends from the labial aspect of the residual ridge to the lip. A passive frenum and has no active muscle fibers. A v-shaped notch (labial notch) should be provided very carefully which should be narrow but deep enough to avoid interference and should snugly around frenum if peripheral seal is to be achieved. https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/   Labial & buccal frenum Buccal frenum has the attachment of following muscles; levator anguli oris, orbicularis oris and buccinator. It needs greater clearance on buccal flange of the denture (shallower and wider) than the labial frenum. https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/   Labial & buccal vestibule (sulcus) Labial sulcus is bounded on one side by the teeth, gingiva and residual alveolar ridge and on the outer side by lips. It runs from one side of the buccal frenum of one side to the other side ; dividing in two compartments-left and right by the labial frenum. https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/   Labial & buccal vestibule (sulcus) Buccal sulcus extends from buccal frenum anteriorly to the hamular notch posteriorly. The size of the vestibule is dependant upon: Contraction of buccinator muscle. Position of the mandible. Amount of bone loss in maxilla. https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/   Hamular notch It is depression situated between the maxillary tuberosity and the hamulus of the medial pterygoid plate. It is a soft area of loose connective tissue. Significance : it houses the disto-lateral termination of the denture. Aids in achieving posterior palatal seal. Overextension causes soreness. Underextension causes poor retention. https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/   Posterior palatal seal area (post-dam) It is a soft tissue area at or beyond the junction of the hard and soft palates on which pressure within physiological limits can be applied by a complete denture to aid in its retention. https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/   Posterior palatal seal area (post-dam) Parts: Pterygomaxillary seal – The part of the posterior palatal seal that extends across the hamular notch and extends 3-4 mm anterolaterally to end in the mucogingival junction on the posterior part of the maxillary ridge. Postpalatal seal – This is a part of the posterior palatal seal area that extends between the two maxillary tuberosities. https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/   Posterior palatal seal area (post-dam) Extensions: Anteriorly – Anterior vibrating line Posteriorly – Posterior vibrating line Laterally – 3-4 mm anterolateral to hamular notch WHAT IS VIBRATING LINE? An imaginary line drawn across the posterior part of the palate that marks the division between the movable and immovable tissue of the soft palate which can be identified by asking the patient to say ‘ah’. It is extending from one hamular notch to the other hamular notch; lying usually 2mm in front of fovea palatinae. https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/ https://sites.google.com/a/atsu.edu/complete-dentures/_/rsrc/1602275638654/palatal-seal/post%20dam.jpg?height=265&width=400   Posterior palatal seal area (post-dam) Functions of the posterior palatal seal: Aids in retention. Prevents food accumulation. Compensation for polymerization shrinkage. Reduces the tendency for gag reflex as it prevent the formation of the gap. between the denture base and soft palate during functional movement. https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/  The distal end of the denture must : cover the tuberosities extend into the hamular notches It should end 1-2 mm posterior to the vibrating line https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/  SUPPORTING STRUCTURES  Primary stress bearing area / Supporting area 1.Posterior part of the palate 2.Posterolateral part of the residual alveolar ridge  Secondary stress bearing area / Supporting area 1.The palatal rugae area 2.Maxillary tuberosity https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/  RELIEF AREAS Incisive papilla Mid-palatine raphe Crest of the residual alveolar ridge Fovea palatinae https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/   Incisive papilla Midline structure situated behind the central incisors. It is an exit point of nasopalatine nerves and vessels. It should be relieved if not, the denture will compress the nerve or vessels and lead to necrosis of the distributing areas and paresthesia of anterior palate. https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/   Mid-palatine raphe Extends from incisive papilla to distal end of hard palate. Median suture area covered by thin submucosa Relief is to be provided as it is supposed to be the most sensitive part of the palate to pressure Incisive papilla https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/   Crest of the residual alveolar ridge Cuspid Eminence https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcRYk7QeAXPOWDjVjqzxbmuEhOVD1VowvWQZAQ&usqp=CAU   Fovea palatinae Few areas like the cuspid eminence , fovea palatinae and torus palatinus may be relieved according to condition required. https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/  Anatomical Landmarks – MANDIBLE https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/  LIMITING STRUCTURES Labial, lingual & buccal frenum Labial & buccal vestibule Alveololingual sulcus Retromolar pad Pterygomandibular raphe https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/   Labial, lingual & buccal frenum It is fibrous band extending from the labial aspect of the residual alveolar ridge to the lip containing a band of the fibrous connective tissue the that helps in attachment of the orbicularis oris muscle. It is quite sensitive hence the denture should have an appropriate labial notch. The fibers of buccinator are attached to the buccal frenum. https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/   Labial, lingual & buccal frenum Should be relieved to prevent displacement of the denture during function. The lingual frenum relief should be provided in the anterior portion of the lingual flange. This anterior portion of the lingual flange called sub-lingual crescent area. The lingual notch of the denture should be well adapted otherwise it will affect the denture stability. https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/ https://www.researchgate.net/profile/Martha-Ann-Keels/publication/6604266/figure/fig2/AS:278614256963600@1443438223628/Heart-shaped-tongue- due-to-tethering-by-the-frenu.png   Labial & buccal vestibule The labial sulcus runs from the labial frenum to the buccal frenum on each side. Mentalis muscle is quite active in this region. The buccal sulcus extends posteriorly from the buccal frenum to outside back corner of the retromolar region. Area maximization can be safely done here as because the fibers of the buccinator runs parallel to the border and hence displacing action due to buccinator during its contraction is slight. The impression is the widest in this region. https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/   Alveololingual sulcus Between lingual frenum to retromylohyoid curtain. Overextension causes soreness and instability. It can be divided into three parts: https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/   Alveololingual sulcus Anterior part : From lingual frenum to mylohyoid ridge The shallowest portion(least height) of the lingual flange https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/   Alveololingual sulcus Middle region : From the premylohyoid fossa to the the distal end of the mylohyoid region https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/   Alveololingual sulcus Posterior portion : From the end of the mylohyoid ridge end to the retromylohyoid curtain Provides for a valuable undercut area so important retention Overextension causes soreness and instability Proper recording gives typical S –form of the lingual flange https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/   Retromolar pad Pear-shaped triangular soft pad of tissue at the distal end of the lower ridge is referred to as the retromolar pad. It is an important structure, which forms the posterior seal of the mandibular denture. The denture base should extend up to 2/3rd of the retromolar pad triangle. https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/  Pterygomandibular raphe The pterygomandibular raphe (pterygomandibular ligament) is a ligamentous band of the buccopharyngeal fascia, attached superiorly to the pterygoid hamulus of the medial pterygoid plate, and inferiorly to the posterior end of the mylohyoid line of the mandible. https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/  SUPPORTING STRUCTURES  Primary stress bearing area / Supporting area Buccal shelf area  Secondary stress bearing area / Supporting area Residual alveolar ridge https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/  Primary stress bearing area / Supporting area  Buccal shelf area Extends from buccal frenum to retromolar pad. Between external oblique ridge and crest of alveolar ridge. Its boundaries are: 1. Medially the crest of the ridge 2. Laterally the external oblique ridge 3. Distally the retromolar pad 4. Mesially the buccal frenum The width of this area increases as the alveolar resorption continues. https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/  Secondary stress bearing area / Supporting area  Residual alveolar ridge Buccal and lingual slopes are secondary stress bearing areas. https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/  RELIEF AREAS Mylohyoid ridge Mental foramen Genial tubercle Torus mandibularis https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/  Mylohyoid ridge Attachment for the mylohyoid muscle. Running along the lingual surface of the mandible. Anteriorly: the ridge lies close to the inferior border of the mandible. Posteriorly it lies close to the residual ridge. Covered by the thin mucosa which may be traumatized by denture base hence it should be relieved. The extension of the lingual flange is to be beyond the palpable position of the mylohyoid ridge but not in the undercut. https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/  Mental foramen Lies on the external surface of the mandible in between the 1st and the 2nd premolar region. It should be relieved specially in case it lies close to the residual alveolar ridge due to ridge resorption to prevent parasthesia. https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/  Genial tubercle Area of muscle attachment (Genioglossus and Geniohyoid). Lies away from the crest of the ridge. Prominent in resorbed ridges therefore adequate relief to be provided. https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/  Torus Mandibularis Abnormal bony prominence. Bilaterally on the lingual side near the premolar area. Covered by thin mucosa so it should be relieved. https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/ https://marlin-prod.literatumonline.com/cms/attachment/2119433510/2093759531/gr1.jpg  A Comparison Between Edentulous Jaws Maxilla Mandible 1. Has more supporting areas 1. Has less supporting area. 2. Limiting structures are less in number 2. Limiting structures are more in number 3. Have a less stronger influence over the 3. Have a stronger influence over the denture border denture border https://mydentaltechnologynotes.wordpress.com/2018/06/19/complete-denture-anatomical-landmarks/