Docademy Removable Prosthodontics 1 PDF

‫‪Docademy‬‬ ‫‪#2‬‬ ‫مدير األكاديمية عمر الحريبات‪app‬‬ ‫‪0792149318 Whats‬‬ "INTRODUCTION TO REMOVABLE PROSTHODONTICS" Let’s go through the: Anatomy of edentulous maxilla ❖ Principles of removable complete dentures: 1. Retention: ▪...

‫‪Docademy‬‬ ‫‪#2‬‬ ‫مدير األكاديمية عمر الحريبات‪app‬‬ ‫‪0792149318 Whats‬‬ "INTRODUCTION TO REMOVABLE PROSTHODONTICS" Let’s go through the: Anatomy of edentulous maxilla ❖ Principles of removable complete dentures: 1. Retention: ▪ The ability of the denture to resist forces displacing the denture in the direction(s) opposite to the path of insertion. ▪ Ability of the denture to resist dislodgment. 2. Support: The ability of the denture to resist tissue-ward movement (inward movement). 3. Stability: ▪ The ability of the denture to resist dislodgment forces that are not parallel to the path of insertion axis. ▪ The ability of the denture to resist lateral (sideways movement). 2 ❖ Dentures contact mucosa with a continuum of compressibility and movement that varies between each arch, among areas within the arch, and among patients. ❖ Short-term and long-term health of the contacting tissues is influenced by the methods used to capture these tissues and the final adaptation of the denture bases in function. ❖ Maximum extension of the denture base increases surface area and spreads the “pressure” of mastication and tooth contacts during swallowing over a greater surface area. ❖ One can regard the intaglio surface of a denture as comprising two areas: a stress- bearing (or supporting) area and a peripheral (or limiting) area. Supporting structures:(Denture bearing area/Denture Foundation) ❖ The foundation for dentures is made up of bone and covering soft tissues(mucosa). ❖ The denture base rests on the mucous membrane, which serves as a cushion between the denture base and the supporting bone. ❖ Primary stress-bearing areas generally have thicker mucosa and/or underlying bone that is less subject to resorption because it is cortical bone. 3 ❖ Maxillary and mandibular stress-bearing areas: 1. Maxillary: - Primary stress bearing areas: ▪ Firm tuberosities. ▪ Hard palate on either side of palatal raphe(the palatal raphe is not a stress- bearing area). - Secondary stress bearing areas: ▪ Alveolar ridge. ▪ Rugae area. 2. Mandible: - Primary stress bearing areas: ▪ Buccal shelves. ▪ Retromolar pads. - Secondary stress bearing area: alveolar ridge. ❖ Mucous membrane ▪ Mucosa: - Stratified squamous epithelial cells. - Lamina propria. ▪ Submucosa: - Connective tissue, it varies in:  Character from dense to loose areolar tissue  Thickness  Provides resiliency  We need this in managing complete dentures. 4  ▪ Residual ridge mucosa:  Keratinized mucosa is the remaining gingival tissue after extraction, it has excellent stress-bearing capacity.  The surgeon should pay attention to maintain all of this available gingival tissue when closing the extraction sites.  On the crest of the ridge: in a healthy mouth, it is firmly attached to the periosteum of the bone by the connective tissue of the submucosa.  Greater bone resorption leads to loosely attached mucosa, making it movable (displaceable) tissue ➔ Unfavorable denture situation!  Greater bone resorption ➔ Increase compressibility of the tissue➔ Unfavorable denture situation!  When the submucosal layer is thin, the soft tissues will be less resilient, the mucous membrane will be easily traumatized, so it will need Relief.  When the submucosal layer is loosely attached or inflamed ➔ more displaceable and compressible mucosa, respectively. Concept of relief: - Area on the fitting surface of the denture that is reduced to eliminate pressure. - Simply, provide more space between the denture surface and the tissue. ❖ Areas requiring relief in impression: imp - 2o stress bearing areas. - Palatal torus and Mandibular tori. - Median palatal raphe. - Retro-mylohyoid ridge. - Undercuts or sharp boney prominences on ridges. 5  As the mucous membrane extends from the crest along the slope of the residual ridge to the vestibular reflection, it loses its firm attachment to the underlying bone.  The more loosely attached mucous membrane in this region has a nonkeratinized or slightly keratinized epithelium, and the submucosa contains loose connective tissue and elastic fibers.  This tissue does not withstand the forces of mastication as well as the mucous membrane covering the crest of the ridge. Residual ridge: ▪ It varies in size and shape between individuals. ▪ U, V, and square arch forms. ▪ After teeth extraction, the width and height of the residual alveolar ridge change, the greatest in the first 6 to 12 months, but it continues at a reduced rate throughout life. ▪ The ridge crest is a secondary supporting area. ▪ The lateral walls of the ridges give stability against denture lateral displacement and create the peripheral seal. ▪ The maxillary anterior alveolar ridge is proclined, so the resorption of the ridge creates a smaller maxillary base. ▪ The mandibular dentition is positioned significantly lingual to the basal bone of the mandible, so the resorption creates a denture-bearing area that is in a more buccal position with a flatter and wider mandibular base. ▪ Outward positioning of the mandible and inward positioning of the maxillae so jaw relationships appear prognathic. 6  Hard palate: ▪ The two palatine processes of the maxilla (anteriorly) and the palatine bone (posteriorly) form the foundation for the hard palate and provide considerable surface area and support for the denture. ▪ Covered by keratinized epithelium of varying thickness. ▪ Medial palatal suture (11): the submucosa is extremely thin, mucosa is not resilient making it easily traumatized if compressed , so it needs Relief! ▪ On either sides of the raphe:  Anterolaterally ➔ Submucosa contains adipose tissue.  Posterolateral ➔ Submucosa contains salivary glands.  The horizontal part provides the primary support area for the denture. Rugae area: number (13)  Mucosal ridges on the anterior third of the palate.  Participate in speech and in suction in children.  Secondary support area. ▪ Palate is set at an angle to the residual ridge. ▪ Thin mucosa. 7  Incisive papilla: number (12)  The submucosa covering the incisive papilla and the nasopalatine canal contains the nasopalatine vessels and nerves.  Located at the line behind and between the central incisors.  Gives an indication on the amount of resorption.  Relief is needed to avoid impinging on the nasopalatine vasculature. Tuberosities: number (7)  Dense fibrous connective tissues with minimal compressibility (Firm).  Primary support area.  When no opposing teeth exist in the mandible ➔ hypertrophy ➔ Interfere with mandibular denture.  The need for surgical tuberosity reduction should always be evaluated. Torus palatinus:  Hard bony enlargement that occurs in the midline of the roof of the mouth.  Covered by a thin layer of mucous membrane that is easily traumatized by the denture base.  If the torus extends posteriorly to the vibrating line, it may need to be surgically reduced in order to achieve a posterior palatal seal and adequate denture retention. 8  Peripheral border tissue (Limiting structures): 1. Labial vestibule: number (2) ▪ Runs from one buccal frenum to the other on the labial side of the ridge. ▪ Divided into left and right vestibule by the labial frenum. 2. Labial frenum: ▪ Starts superiorly in a fan shape and converges as it descends to its terminal attachment on the labial side of the ridge. ▪ It contains no muscle and has no action of its own,it is moved by the Orbicularis oris, zygomatic major and minor and the buccinator muscles. ▪ This makes space in the denture border (flange) to accommodate the movements. 3. Buccal Frenum: number (3) ▪ Forms the dividing line between the labial and buccal vestibules. ▪ A single or double fold or even a broad-fan shape. ▪ The orbicularis oris pulls the frenum forward, and the buccinator pulls it backward. ▪ It requires more (broad) relief. 9 4. Buccal vestibule: number (4) ▪ Lies opposite the tuberosity and extends from the buccal frenum to the hamular notch. ▪ Buccal vestibule size varies with:  Contraction of the buccinator muscle.  Position of the mandible (Coronoid process).  Amount of bone lost from the maxilla. ▪ Distal to the buccal frenum and palpable superior to the vestibule is the root of the zygoma, which is located opposite the first molar region, it may require relief when resorption is extensive. 5. Hamular notch: number (8) ▪ Forms the distal limit of the buccal vestibule. ▪ Situated between the tuberosity and the hamulus of the medial pterygoid plate. ▪ It can be palpated with a mouth mirror or T-shaped burnisher. 6. Incisive papilla: number (12) ▪ The mucous membrane of the hamular notch consists of a thick submucosa made up of loose areolar tissue, it is compressible, this achieves peripheral seal and retention. ▪ The pterygomandibular raphe, covered by mucosa, extends from the hamulus inferiorly into the retromolar pad of the mandible, it moves forward when opening the mouth. ▪ Avoid denture overextension. 10 7. Vibrating line: ▪ Marks the junction between the movable and non-movable part of the soft palate. ▪ Tissue anterior to this line is compressible ➔ Achieve peripheral seal and retention. ▪ The vibrating line is more of an area and is always on the soft palate. ▪ Lateral border terminates through the hamular notches. ▪ At the midline, it usually passes 1 to 2 mm anterior to the fovea palatinae. ▪ The distal end of the denture should extend to the vibrating line. 8. Fovea palatinae: ▪ Two small depressions on the posterior aspect of the soft palate. ▪ Coalescence of mucus glands ducts. ▪ Usually located 1-2mm posterior to the vibrating line. ▪ The distance from the vibrating line may vary but they are always posterior to it. ❖ So: ▪ To maximize the success of complete denture treatment, the requirements of retention, support and stability should be fulfilled. ▪ Understanding the structure and function of the anatomical landmarks plays an important role in complete denture treatment success and health and disease of the edentulous patient. ▪ Relate the anatomy to function and integrate this into clinical and laboratory practice. 11