Pre-Clinical Removable Prosthodontics (Complete Denture) PDF

Pre-Clinical Removable Prosthodontics (Complete Denture) Dr: Sherin Donia ANATOMY AND PHYSIOLOGY IN RELATION TO COMPLETE DENTURE CONSTRUCTION Oro-Facial Anatomical Landmarks Extra-oral Intra-oral Maxillary Mandibular Supporting Limitin...

Pre-Clinical Removable Prosthodontics (Complete Denture) Dr: Sherin Donia ANATOMY AND PHYSIOLOGY IN RELATION TO COMPLETE DENTURE CONSTRUCTION Oro-Facial Anatomical Landmarks Extra-oral Intra-oral Maxillary Mandibular Supporting Limiting Supporting Limiting A- Anatomical landmarks of the denture bearing area Maxillary landmarks 1-Crest of the ridge 2- Maxillary tuberosity 3- Median palatine raphe 4- Incisive papilla 5- Rugae area 6- Torus palatinus 7- Fovea palatinae 8- Hard palate The anatomic landmarks of significance in relation to maxillary and mandibular complete denture impressions can be discussed as: 1- Supporting areas. A- Primary stress-bearing areas. B- Secondary stress-bearing areas. 2- Relief areas. 3- Limiting areas.  Maxillary intra-oral landmarks 1. Residual alveolar ridge: It is that portion of the alveolar process and its covering soft tissue that remains after extraction of teeth. The highest part of the ridge is called the crest of the ridge. It is considered the primary stress bearing area in the upper arch as it is covered with a layer of dense fibrous connective tissue that is favorable for supporting the denture.  Maxillary intra-oral landmarks 2. Maxillary tuberosity: It is a rounded bony prominence that is located just behind and above the distal end of the maxillary ridge. It should be covered by the denture as it plays a role in retention and support of the maxillary denture. In some cases, extremely large tuberosities may need surgical correction before complete denture construction in order not to interfere with denture insertion.  Maxillary intra-oral landmarks 3.Median palatine raphe: It is a thin mucoperiostium that covers the median palatine suture. It may be hard or sensitive. Lack of relief of the median palatine raphe would result in rocking of the denture with subsequent midline fracture.  Maxillary intra-oral landmarks 4. Incisive papillae: It is pear-shaped elevation of soft tissue at the midline just palatal to the upper centrals. It covers the incisive foramen through which the nasopalatine nerves and vessels pass. After extraction of teeth and alveolar bone resorption, it migrates to the crest. It should be relieved to avoid interference with blood and nerve supply which might cause burning sensation.  Incisive Papilla It also acts as a guide for anteroposterior position of the central incisors as the labial surfaces of the upper centrals are usually located 8 to 10mm labial to the middle of the incisive papilla. The line passing at the distal aspect of the papilla parallel to the posterior palatal seal is an indicator for the position of the canines.  Maxillary intra-oral landmarks 5. Palatine rugae: It is irregular ridges of dense connective tissue radiating from anterior one third of the hard palate on both sides of the midline. It is associated with the sense of taste and function of speech. Its serves as a secondary stress bearing area in the maxillary arch if it is less prominent. They also enable the tongue to form a perfect seal when it is pressed against the palate in making the linguopalatal sounds like "S" sound. Copying the rugae on the palatal surface of a denture helps to reduce the disability in some cases.  Maxillary intra-oral landmarks 6. Torus palatinus: It is a bony bulge sometimes present in the midline of the palate. It varies in size and form. If it is small, the denture base over this area should be relieved. If it is large, it is surgically removed.  Maxillary intra-oral landmarks 7. Fovea palatinae: These are two small pits found on each side of the midline just posterior to the junction of hard and soft palate. They are openings of the ducts of minor salivary glands. The posterior border of the maxillary denture should extend 2 mm posterior to the fovea palatinae. Maxillary arch showing: incisive papilla (IP), maxillary tuberosity (MT) and the hamular notch (HM). Mandibular Landmarks- Buccally. Mandibular Landmarks- Lingually  Mandibular intra-oral landmarks 1- Residual alveolar ridge: It is that portion of the alveolar process that remains after extraction of teeth. The highest part of the ridge is called the crest of the ridge. It is formed of cancellous bone. Sometimes, in severe resorption, it appears as flabby tissue. This case necessitates special impression technique or surgical intervention as it impairs denture stability. Mandibular alveolar ridge showing: crest of the ridge (*) and the retromolar pad areas (RP).  Mandibular intra-oral landmarks 2. External Oblique ridge : It is a dense bony ridge descending obliquely from the ramus of the mandible downward and forward till it fades at the mental foramen. The mandibular denture should cover but not extend beyond the external oblique ridge to avoid denture displacement by the powerful masseter muscle  Mandibular intra-oral landmarks 3. Buccal Shelf of bone(Buccal plateau): It is bordered externally by the external oblique line and internally by the slope of the residual ridge. This region is a primary stress bearing area in the mandibular arch because it is lies horizontal (parallel to the occlusal plane) and the bone is very dense (compact bone). Thus, It must be covered by the denture to provide support.  Mandibular intra-oral landmarks 4. Mental Foramen: It is located on the buccal surface of the mandible in the premolar region between the roots of the first and second premolars. The mental nerves and blood vessels pass through it. The anterior exit of the mandibular canal and the inferior alveolar nerve. In cases of severe residual ridge resorption, the foramen occupies a more superior position. The denture base must be relieved to prevent nerve compression and pain and cause numbness of the lower lip.  Mandibular intra-oral landmarks 5. Retromolar pad: It is pear shaped pad of soft tissue present bilaterally at the distal end of the residual Ridge and anterior to the pterygo-mandibular raphe. It contains mucous glands, tendons, and muscle fibers.  Retromolar pad It should be covered by the mandibular denture to ensure proper extension of the denture. It doesn’t provide support, but covering it is essential to cover the buccal shelf of bone. Help in denture retention Act as cushion (shock absorber ) so it decrease bone resorption. This pad is extremely important in denture construction from both a denture extension and plane of occlusion standpoint.  Mandibular intra-oral landmarks 6. Torus mandibularis: It is a bony prominence sometimes present on the inner surface of the mandible in the premolar region. It varies in size and shape. Relief of the denture base in this area could be made to avoid impingement of the mucosa. If the torus mandibularis is large and prevents proper seating of the lower denture, surgical intervention is necessary.  Mandibular intra-oral landmarks 7. Mylohyoid ridge : (internal oblique ridge) It is a bony ridge extending on the medial surface of the mandible from the third molar region to the lower border of the mandible near the midline. it represents the attachment of mylohyoid muscle  Mandibular intra-oral landmarks Dentate Mandible-No resorption Moderate resorption Mylohyoid ridge should be included in the denture bearing area. Thin and sharp mylohyoid ridge should surgically recountoured Severe resorption  Mandibular intra-oral landmarks 8.Genial tubercles: Two small bony projections present on the medial surface of the mandible and serve as the attachment sites of the genioglossus and geniohyoid muscles. In patients’ with severe ridge resorption.lt may cause discomfort if they are exposed to the denture base so it have to be relieved.  Mandibular intra-oral landmarks 9. Tongue: It is a powerful muscle where the dorsum rests against the roof of the mouth and the tip rests in contact with the lingual surfaces of the lower incisor teeth. The lateral borders lie against the lingual borders of the posterior teeth  Mandibular intra-oral landmarks Teeth have to be set on the crest of the ridge with the occlusal plane lower than the highest convexity of the tongue in order to avoid cramped tongue and allow the tongue to reflect the food on the occlusal surface ANATOMY AND PHYSIOLOGY IN RELATION TO COMPLETE DENTURE CONSTRUCTION Oro-Facial Anatomical Landmarks Extra-oral Intra-oral Maxillary Mandibular Supporting Limiting Supporting Limiting Limiting Structures  Maxillary limiting structures 1. Labial Frenum It is a fold of mucous membrane present in the midline It must be relieved in the denture by making V-shaped notch in the labial flange opposite to its position.  Maxillary limiting structures 2. Labial Vestibule It Is the reflection of the mucosa of the lip to the mucosa of the alveolar process. The denture in this area is in relation to the orbicularis oris and the superior incisive muscles. These muscles limit the thickness and the length of the labial flange of the denture.  Maxillary limiting structures 3. Buccal Frenum It is a fold of mucous membrane that varies in size, number and position. A V-shaped notch is made in the denture flange opposite to its position to facilitate its functional movements. Inadequate clearance in buccal flange to allow its movement will cause dislodgment of the denture.  Maxillary limiting structures 4. Buccal Vestibule It Is the reflection of the mucosa of the cheek to the mucosa of the alveolar process. The denture in this area is related to buccinator muscle. Due to the horizontal direction of the fibers of this muscle contraction of this muscle will not displace the denture. Buccal flanges must extend in the buccal vestibule.  The attachment of the buccinator muscles limits the depth and thickness of the denture flange in the buccal vestibule. At the distobuccal area the flange thickness is affected also by the movement of the coronoid process. Excessive flange thickness in this area can cause denture displacement and subsequent mucosal injury during movements. Normal attachments of buccinator muscle on the maxilla and mandible.  Maxillary limiting structures 5. Hamular Notch (pterygo-maxillary notch) It is a notch located between the maxillary tuberosity anteriorly and the pterygoid hamulus posteriorly. It is one of the important landmarks for determination of the posterior limit of the upper denture. A straight line from hamular notch on one side to the other side determines the posterior limit of the upper denture.  Maxillary limiting structures 6. Vibrating Line ( Ah Line) ▪ It separates the movable part from the immovable part of the soft palate. ▪ This line is 2mm posterior to the fovea palatine. ▪ This line determines the posterior end of the upper denture.  Maxillary limiting structures 1. Labial frenum 2. Labial vestibule 3. Buccal frenum 4. Buccal vestibule 6. Vibrating line 5. Hamular notch Anatomical landmarks influencing the labial and buccal maxiary denture periphery An illustration of the and Maxiallary denture landmarks and borders. The surrounding musculature is essential to activate the muscles and produce a perfect impression.  Mandibular limiting structures 1. Labial Frenum It is a fold of mucous membrane present in the midline extending from the inner surface of the mandibular lip toward the crest of the residual ridge Denture should be notched opposite to it.  Mandibular limiting structures 2. Labial vestibule It is the reflection of the mucosa of The lip to the mucosa of the alveolar ridge extending from the labial frenum to the buccal frenum. The denture flange in this area is in relation to the orbicularis oris muscle and the incisivus labii inferioris muscle Limits the denture flange thickness and length.  Mandibular limiting structures 3. Buccal Frenum It is a fold of mucous membrane in the premolar area. Movement of the lip and the cheek move the frenum. It varies in shape, size and number. A notch is made in the lower denture to accommodate the frenum and to facilitate its functional movement.  Mandibular limiting structures 4. Buccal Vestibule It is the reflection of mucous membrane from the cheek to the alveolar ridge distal to the buccal frenum. The denture in this area is related to the buccinator muscle. Its contraction does not displace the lower denture so flanges of the lower denture must extend in the buccal vestibule.  Mandibular limiting structures 5. Masseter muscle influencing area (Masseteric Groove) The distobuccal flange of the denture should be converge in a medial direction to allow freedom for masseter muscle to contract otherwise the denture will be displaced or the patient will experience soreness in this area. Just buccal to the crest of the mandibular ridge in the distal-buccal corner of the arch is an area known as the masseter notch, or groove area (A). The most distal extent of the inner surfaces of the mandibular ridges ends in an area called the retromylohyoid area, or fossa (B).  Mandibular limiting structures 6. Posterior end of retromolar pad It constitutes the posterior limit of the lower denture at which post damming can be performed.  Mandibular limiting structures 7- Pterygo mandibular raphe and anterior border of the ramus: ❑Distally, the mandibular denture is in relation to the pterygo mandibular raphe and the anterior border of the ramus. ❑ The raphe is relaxed when the patient is closing. It is only activated and moves anteriorly with wide jaw opening. ❑ The mandibular denture should extend to cover the retromolar pad till the anterior border of the ramus. Pterygo mandibular raphe Extending from the hamulus above to the area of the retromolar pad below is the pterygomandibular raphé fold which underlies the fold, is the junction between the buccinator (cheek muscle) and the superior constrictor muscle of the pharynx. On the lingual side, starting backward and passing forward, the lingual flange is related to the latter structures: Pterygo mandibular raphe  Mandibular limiting structures 8. Palatoglossal arch The distolingual border of the mandibular denture is related to the palatoglossal arch. which is formed mainly by the palatglossus muscle. Denture overextension in this area will cause sore throat.  Mandibular limiting structures 9. Lingual Pouch Anterior to the palatoglossal arch, the denture flange is related to the lingual pouch. Lingual pouch is a very important landmark in the mandibular arch as it includes an undercut area that provides mechanical means of retention for the mandibular denture.  Mandibular limiting structures 10. Mylohyoid muscle influencing area. (internal oblique ridge) Anterior to the lingual pouch, the denture flange is related to the mylohyoid muscle. The lingual flange should extend to the mucolingual sulcus as determined by the functional movement of the mylohyoid muscle.  Mandibular limiting structures 11. Sublingual salivary gland area. More anteriorly, the lingual flange is related to the sublingual salivary gland. The lingual flanges of the lower denture should not extend in this area because with excessive resorption of the mandible the gland may bulge superiorly above the body of the mandible. Therefore it affects the depth of the lingual flange at this area.  Mandibular limiting structures 12. Lingual Frenum More anteriorly a fold mucous membrane attach the mucosa of the undersurface of the tongue to mucosa of the floor of the mouth. It moves with the movement of the tongue so a notch is made to accommodate the frenum. An illustration of the and Mandibular denture landmarks and borders. The surrounding musculature is essential to activate the muscles and produce a perfect impression. Anatomical landmarks influencing the labial and buccal mandibular denture periphery Intra-Oral Landmarks of Prosthetic Importance Figure 8-4 A, Maxilla: 1, labial frenum (not visible); 2, labial vestibule; 3, buccal frenum; 4, buccal vestibule; 5, coronoid bulge; 6, residual alveolar ridge; 7, maxillary tuberosity; 8, hamular notch; 9, posterior palatal seal region; 10, foveae palatinae; 11, median palatine raphe; 12, incisive papilla; 13, rugae; 14, displaceable soft and hard palate. B, Maxillary denture shows the corresponding landmarks: 1, labial notch; 2, labial flange; 3, buccal notch; 4, buccal flange; 5, coronoid contour; 6, alveolar groove; 7, area of tuberosity; 8, pterygomaxillary seal in area of hamular notch; 9, area of posterior palatal seal; 10, foveae palatinae; 11, median palatine groove; 12, incisive fossa; 13, rugae; 14, “butterfly” outline of posterior palatal seal. Figure 8-12 A, The anatomy and related denture form is noted here. 2, labial vestibule; 3, buccal frenum; 4, buccal vestibule; 5, residual alveolar ridge; 6, buccal shelf; 7, retromolar pad; 8, pterygomandibular raphe; 9, retromylohyoid fossa; 10, alveololingual sulcus; 11, sublingual caruncles; 12, lingual frenum; 13, region of premylohyoid eminence. B, Mandibular denture revealing 1, labial notch; 2, labial flange; 3, buccal notch; 4, buccal flange; 5, alveolar groove; 6, buccal flange, which covers the buccal shelf; 7, retromolar pad; 8, pterygomandibular notch; 9, lingual flange with extension into retromylohyoid fossa, 10, lingual flange; 12, lingual notch; 13, area of premylohyoid eminence.