Anatomy of Denture Bearing Areas PDF

ANATOMY OF DENTURE BEARING AREAS  INCISIVE PAPILLA – This soft tissue overlies the incisive canal through which pass the nerve...

ANATOMY OF DENTURE BEARING AREAS  INCISIVE PAPILLA – This soft tissue overlies the incisive canal through which pass the nerves and vessels supplying anterior part of the palatal mucosa. The labial surface of the natural central incisor lie approximately 8-10 mm anterior to the center of the papilla, a relationship which should be borne in mind when positioning artificial replacement  RUGAE. Irregular transverse mucosal ridges occurring in the anterior part of the hard palate. This is an area of the fine tactile discrimination and partial dentures should therefore be designed to leave as Much of this area uncovered as From this view, the anterior possible. border of the denture shown here is preferable to the border indicated by the dotted line.  1. PALATINE RAPHE. A mucosal ridge lying sagittally in the midline of the palate. 2 PALATINE TORUS. A developmental bony prominence sometimes seen in the center of the palate. This structure is often covered by relatively incompressible mucoperiosteum. A mucosally supported denture may need to be relieved over the torus to prevent rocking.  VIBRATING LINE. The junction between the movable mucosa of the soft palate and the static mucosa of the hard palate. If decision has been taken to cover a large area of palate with the partial denture connector, the posterior border of the connector should be positioned on the compressible tissue just anterior to the vibrating line.  1. PALATINE FOVEA. The orifices of common collecting ducts of minor palatine salivary glands which are often to be found close to vibrating line.(anteriorly) 2. HAMULAR NOTCH. Mucosal depression posterior to the maxillary tuberosity. The notch overlies the gap between pterygoid hamulus and maxillary tuberosity and marks the posterior limit of extension of an upper saddle where there is no distal abutment tooth.  PALATINE SUBMUCOSA. Variation in thickness of the submucosa influence the compressibility of the denture-bearing surface and consequently the degree of mucosal support offered to a partial denture SURFACE ANATOMY OF MANDIBLE  BUCCAL SHELF. This lies between crest of ridge and external oblique ridge. Broad horizontal surface covered with smooth cortical bone makes it a major support area of mandibular residual ridge and important in the support of free-end saddle.  RETROMOLAR PAD. The anterior part of this pad is usually firm and fibrous and forms an important part of denture bearing area. Offers support for denture and helps to resist posterior displacement. The posterior part is mobile and falls outside the denture bearing area. In the absence of upper and lower posterior teeth a point halfway up the retromolar pad may be used to indicate the occlusal plane level.  MYLOHYOID RIDGE. The bony ridge to which the mylohyoid muscle is attached. As resorption of the residual ridge proceeds, the prominence of mylohyoid ridge increase predisposing to mucosal soreness beneath the denture in this area.  RETROMYLOHYOID AREA (LINGUAL POUCH) the part of the lingual sulcus lying behind the mylohyoid ridge posteriorly. Whenever the functional movements of the sulcus permits, the lingual flange of a free-end saddle should be extended into this area to provide optimum stability.  MANDIBULAR TORI. Developmental swellings occasionally seen lingually in the the premolar region. Bilateral, sometimes multiple and symmetrical. May prevent the optimum positioning of lingual major connector and may need to be removed surgically.  SULCUS. Mucosal lying between the ridge on the one hand and the cheeks, lips or tongue on the other. In majority case the denture flanges will need to fill the dimension of the sulci so recorded. Important to obtain an accurate recording to form lingual sulcus that determine the postion of lingual connectors  FRENUM. Fold mucous membrane which crosses the sulcus and contains fibrous submucosa but no muscle fibers. Require sufficient clearance by denture border to allow their unimpeded movement in function ANATOMY OF THE BUCCAL SULCI RELATED TO THE BORDER OF UPPER AND LOWER DENTURES ANATOMY OF THE BUCCAL SULCI RELATED TO THE BORDER OF UPPER AND LOWER DENTURES  B- BUCCINATOR, DAO- DEPRESSOR ANGULI ORIS, II- INCISIVUS INFERIOR, IS- INCISIVUS SUPERIORIS, LAO- LEVATOR ANGULI ORIS, OO- ORBICULARIS ORIS, ZM- ZYGOMATICUS MAJOR MODIOLUS. Decussation of muscle fibers near the angle of the lips. Can fix the corner of the mouth in any position required for function and during mastication it closes the buccal sulci to prevent food escape.. The closing movement of the mandible is effected by the A. relaxation of the lateral pterygoid muscle (not elevator) B. synergism of retracting portions of masseter and temporalis muscles and the retracting components of the depressors C. contraction of the elevators(masseter, temporalis and medial pterygoid)  On clenching the teeth, the anterior border of the masseter muscle bulges into the distobuccal sulcus area. If the flange of the denture is over extended in this area the resulting pressure may lead to soreness and denture diplacement. Failure to contour buccal flange in the premolar region to accommodate the activity of the modiolus also cause displacement of the denture.  Contraction of the buccinator muscle raises soft tissue band at occlusal plane level. The polished surface of the buccal flange should be shaped so that the pressure falling on it from this buccinator activity will have a component of force which is directed towards the ridge, to help retain the denture.  Contraction of mentalis raises the soft tissue of the chin, thus reducing the depth and width of labial sulcus. It there has been marked resorption of the underlying bone, it can exert considerable pressure on the labial flange resulting in posterior and upward displacement.  When the tongue is elevated, the sublingual folds are raised and may greatly reduce depth and width of the sulcus. This phenomenon is marked when advance resorption of the ridge has occured.  When the mandible is moved laterally, the coronoid process on the non working side ( the side from which the mandible is moving)comes into close relationship to the buccal aspect of maxillary tuberosity. The buccal sulcus in this region is thus reduced in width, limiting the space available for a buccal flange. Patient Work Up a. Patient Interview b. Data gathering 1. Chief complaint 2. History of present illness 3. Medical history 4. Dental History 5. Extraoral examination 6. Intraoral examination 27  Intraoral examination 1.Visual- Position of teeth Number of teeth Caries Condition of soft tissues Restorations present Oral Hygiene Design possibilities related to esthetics and function Occlusion Vertical space Horizontal rel’n of mand-maxilla in centric & eccentric positions  Intraoral examination 2. Digital and exploratory- Firmness of teeth Depth of pockets Extent of caries Sensitivity of teeth Condition of restorations present Condition of soft tissue Action of tongue and muscles affecting denture borders  Conditions of restorations present Assess if there is need to change restorative fillings Include in planning the type of restorations for abutments  Site Selection and Preferred Type of Surface for the Rest Teeth Enamel Gold Alloy Amalgam Silicate or Acrylic Resin Maxillary Conventional Full crown, Replace with Replace with teeth molars preparations 3/4 crown, gold if minor gold and usually in inlay, or connector restorations premolars the mesial or onlay contacts the distal fossae proximal surface of the restoration. Canines Cingulum,inl Cingulum Might be Replace with ay, full rest in gold employed gold crown or 3/4 provides the under a restorations crown often ideal surface cingulum needed rest in selected instances Incisors Cingulum Cingulum Replace with Replace with rest (not rest, inlay, gold gold feasible full crown or restorations without a 3/4 crown  Site Selection and Preferred Type of Surface for the Rest Teeth Enamel Gold Alloy Amalgam Silicate or Acrylic Resin Mandibula Conventiona Full crown, Replace with Replace with r teeth l 3/4 crown, gold if clasp gold Molars preparations inlay or onlay connector restorations and in the mesial contacts the Premolars or distal proximal fossae surface of the amalgam Canines Incisal Cingulum Replace with Replace with (usually) rest in crown gold gold or inlay is restorations ideal Incisors Incisal rest Cingulum Replace with Replace with sometimes rest with two gold gold used or more teeth restorations splinted together  Intraoral examination 3. Roentgenographic Pathology ( cysts, tumors, granulomas, etc) Amount of bone support Periodontal pockets Periodontal prognosis Caries Bone index areas  Bone index areas Those areas of bony support which discloses the reaction of bone to abnormal stress. E.g. Areas of bone around abutment teeth or isolated teeth subjected to overloading. Residual ridge Edentulous area of bone supporting a complete or RPD These areas are compared to areas of bone around teeth in normal occlusion (seen in radiographs) Primary or preliminary impression Choose a suitable impression tray Choose a suitable impression material Over extension of border is advisable No voids on critical areas There should be adequate detail captured ******plaster wash impression to remove blood, saliva and other debris 35