RPD Lecture Notes PDF

PROSTHODONTICS 2 I. INTRODUCTION Prostheses – artificial device to replace or augment a missing or impaired part of the PROSTHODONTICS...

PROSTHODONTICS 2 I. INTRODUCTION Prostheses – artificial device to replace or augment a missing or impaired part of the PROSTHODONTICS body.  The branch of dentistry that deals Prosthodontics – the branch of dentistry with the design, fabrications, and that deals with the design, fabrication, and fitting of artificial replacements for fitting of artificial replacements for teeth teeth and other parts of the mouth. and other parts of the mouth. Support - The foundation on which a dental prosthesis rests, or to hold up and serve as a foundation Stability - The quality of a prosthesis to be HISTORY firm stable, or constant.  Replacement of lost teeth have  To resist the displacement by been produced for thousands of functional, horizontal, or rotational years. stresses  First dentures were fabricated from ivory and bone Retention - Is spoken of as that quality  Some cultures also used gold, inherent in the denture that resists the copper, and teeth from animals vertical forces of dislodgement  One breakthrough in prosthodontics Abutment – is a tooth, a portion of a tooth, is the discovery of acrylic resin which or a portion of an implant that serves to is used in most denture bases. support and/or retain a prosthesis. EXAMPLE OF PREHISTORIC DENTURES Height of Contour – a line encircling a tooth, designating its greatest circumference at a selected position determined by a dental surveyor. Undercut – that portion of a tooth that lies between the height of contour and the gingiva. TERMINOLOGIES: Prosthetics – the surgical specialty concerned with the design, construction, and fitting of prostheses Guiding planes – two or more vertically parallel surfaces of abutment teeth shaped to direct a prosthesis during placement and removal. REMOVABLE PARTIAL DENTURES 1  PROSTHODONTICS 2 Residual ridge or Edentulous Ridge – the  Health residual bone, with its soft tissue that covers  Appearance the underlying area of the denture base. Cast/ Dental Cast- an accurate and BRANCHES OF PROSTHODONTICS positive reproduction of a maxillary or mandibular dental arch made from an - Fixed Partial Dentures impression of that arch - Removable Partial Dentures - Complete Dentures Dentulous – an arch/ patient with natural teeth present Edentulous – an arch/ patient with no PARTIAL DENTURES natural teeth/ absence of natural teeth Fixed partial dentures - Cemented, Screwed REMOVABLE PARTIAL DENTURES Removable Partial dentures Removable partial dentures are a Types: component of Prosthodontics, which denotes the branch of dentistry pertaining  All-resin appliance to the restoration and maintenance of oral  Resin with wire clasp functions, comfort, appearance and  Resin with casted clasp health of the patient by the restoration of natural teeth and/or the replacement of missing teeth and craniofacial tissues with EFFECTS OF TOOTH LOSS artificial substitutes. Tooth loss and age are linked to each other. OBJECTIVES OF PROSTHODONTIC INTERarch difference = maxillary before RESTORATION mandibular 1. Elimination of disease INTRAarch difference = posterior before 2. Preservation, restoration, and anterior maintenance of the health of the  Frequently the last remaining teeth remaining teeth and oral tissues in the mouth are in the mouth are 3. Replacement of lost teeth the mandibular anterior teeth, 4. Restoration of normal function especially the mandibular canines. CONSIDERATIONS IN PROSTHODONTIC CONSEQUENCES OF TOOTH LOSS TREATMENT ANATOMICALLY:  Oral Function  Loss of ridge volume  Comfort REMOVABLE PARTIAL DENTURES 2  PROSTHODONTICS 2  Bone loss is greater in mandible than notice a diminished function to a level that is in maxilla unacceptable to them.  Bone loss is more pronounced posteriorly than anteriorly o  Result: broader mandible and constriction of maxilla SUBJECTIVE: the level at which a patient finds FOR THE SOFT TISSUES: function to be  Attached gingiva is replaced with less keratinized oral mucosa unacceptable varies among individuals. Changes in facial features due to: -  Altered lip support An understanding of these variations among  Reduced facial height individuals with a full complement of teeth and those with prostheses can help clinicians formulate realistic treatment goals that can be communicated to the patient. PHYSIOLOGIC: - - A review of oral function, especially mastication, Diminished masticatory efficiency> digestive may help interested clinicians problems better understand issues related to the impact - of removable partial denture Speech function. FUNCTIONAL RESTORATION WITH CLASSIFICATION OF PARTIALLY EDENTULOUS PROSTHESES ARCH - REQUIREMENTS OF AN ACCEPTABLE METHOD OF CLASSIFICATION The loss of teeth can lead a patient to seek care for functional reasons as they It should permit immediate visualization of the type of partially edentulous arch that REMOVABLE PARTIAL DENTURES 3  PROSTHODONTICS 2 is being considered. remaining natural teeth It should permit immediate differentiation CLASS II between tooth-supported and tissue unilateral edentulous area supported RPD. located posterior to the It should be universally acceptable. remaining natural teeth - CLASS III Useless if another dental practitioner would not unilateral edentulous area be able to understand it with remaining natural WHY? teeth both anterior and A classification system facilitates posterior to it. communication between dentists. CLASS IV Since there are several methods of classifying partial denture, the use of non single, but bilateral standard classifications could lead to confusion. edentulous area located Kennedy’s Classification is the most widely anterior to the remaining used and accepted classification of natural teeth partially edentulous arches RULES GOVERNING APPLICATIO OF THE In 1923, Kennedy devised a system that KENNEDY METHOD became popular due to its simplicity and 1. Classification should follow rather than ease of application. precede any extractions of teeth that might CLASS I alter the original classification. (distal extension) 2. If a third molar is missing and not to be replaced, it is not considered in the bilateral edentulous are classification. located posterior to the REMOVABLE PARTIAL DENTURES 4  PROSTHODONTICS 2 3. If a third molar is present and is to be used class II mod 1 as an abutment, it is considered in the Class II Mod 2 classification. Class I, mod 1 4. If a second molar is missing and is not to be Class I mod 3 replaced, it is not considered in the Class IV classification (e. g., if the opposing second Class 3 mod 3 molar is likewise missing and is not to be class II mod 1 replaced). (When the 3rd molar moved mesially) Class IV 5. The most posterior edentulous area (or areas) always determines the classification. Class III mod 1 6. Edentulous areas other than those Class I determining the classification are referred to as not tooth bound, modifications and are designated by their supraerruption and tooth movementClass 3 number. Class1 7. The extent of the modification is not considered, only the number of additional (indicated for semi-CD) edentulous areas. Class II, mod1 8. There can be no modification areas in Class (rare: replacement of 3rd molar) IV arches. (Other edentulous areas lying TREATMENT OPTIONS FOR PATIENTS posterior to the single bilateral areas crossing Tooth replacements from the PATIENT’S the midline would instead determine PERSPECTIVE the classification; see Rule 5.) - Class II, mod 1 Tooth loss is a permanent condition Class IV (permanent dentition) Class II, mod 1 no treatment but are manageable REMOVABLE PARTIAL DENTURES 5  PROSTHODONTICS 2 NATURAL ORDER IS DISRUPTED= chronic o Those that we cannot control medical condition ▪ Accidental trauma - ▪ Parafunctional habits (e.g. bruxism) Prostheses must be managed as well When RPD are suggested, they are seldom recalls for management described in the detail THINGS TO CONSIDER in which fixed or implant prostheses are prescribed, - as they generally are considered less like teeth Expected VS. Unexpected Outcomes and not desirable a replacement. - SHARED DECISION MAKING: EXPECTED OUTCOMES TO ACHIEVE A STATE OF ORAL HEALTH: o Type of prostheses chosen - o Needs that may arise due to degradation of prostheses Patients need to recognize behavioral issues (prone to breakage, wear and tear) - o Retreatment course (time for recall for For tooth replacement decisions = complex management) trade offs consider life expectancy for elder patients SHARED DECISION MAKING - - UNEXPECTED OUTCOMES Addressesthe need to fully inform the patients about risk and benefits o Related to our control of manipulation - ▪ Tissue damage Px’s values and preference play a role in the ▪ Material design flaw final decision ▪ Prosthesis design ACTIVE INQUIRY REMOVABLE PARTIAL DENTURES 6  PROSTHODONTICS 2 - Different types of patients August 26, 2021 o Px who doesn’t want to get involved Types and Components of RPD Restoration o Px’s who wishes to participate PARTIAL EDENTULISM PROSTHETIC OPTIONS  Tooth-supported FPD (short pan) -  RPD  Implant supported prostheses Ultimately, it is our role to help patients o Pwede rin sa distal extension case consider important differences pero magiging abutment lang ng rpd between different prosthesis types.  How well these options restore and maintain the features of natural teeth WHAT THEN DEFINED IMPORTANT depends to a large extent on the DIFFERENCES? numbers and locations of the missing teeth Technical outcomes  The more modification spaces, the more difficult the making of denture is Physical outcomes TYPES OF RPD RESTORATION Esthetic outcomes TOOTH SUPPORTED TOOTH-TISSUE SUPPORTED Maintenance needs Initial and future costs Physiologic Outcomes The replacement and prosthesis ideally should provide function “tooth bound” “distal extension” o Tooth-tissue supported: One and a level of comfort as equivalent as possible abutment then the rest is supported to normal dentition. by residual ridge In achieving this, stability while chewing is a * Removable partial dentures can be designed in various ways to allow use of primary focus of attention, abutment teeth and supporting tissue for stability, support, and retention of the and we should strive to determine what is prosthesis. required to ensure it.  Tooth-bound spaces: RPD is like a fixed partial denture because natural teeth alone provide direct resistance to functional forces. REMOVABLE PARTIAL DENTURES 7  PROSTHODONTICS 2 o Design of RPD and abutment teeth: RETAINER (technically) take advantage of tooth support. BASE MATERIAL Metal bases  Generally o Has more retention than distal can be Acrylic Resin extension cases used o More conservative preparation than FPD DIRECT  Retained  Wrought-wire  Tooth-tissue supported: it is necessary RETENTION and or bar type that the residual ridge be used to assist stabilized by retentive arms in the functional stability of the a clasp prosthesis. o Takes advantage of the residual In the combination tooth- and tissue- ridge supported o Minimal movement (1-3mm)  B = Flat ridge provides good support, *types of RPD based of support = tooth poor stability tissue and tooth-tissue supported  C = Sharp, spiny ridge, provides poor *types of RPD bases on material = ‘all resin support, poor to fair stability appliance” “resin with wire clasp” resin  D = Displaceable tissue on the ridge with casted clasp” provides poor support, poor stability o B is ideal TOOTH TOOTH-TISSUE SUPPORTED SUPPORTED  Because of the anticipated functional movement of the distal extension base, MOVEMENT  Less  More prone to the direct retainer adjacent to the POTENTIAL movement distal extension base must perform still DESIGN  Design is less  More complex another function in addition to that of CONSIDERATION variable design resisting vertical displacement. PRIMARY  Abutment  Residual ride *movement should be 1-3 mm , grater SUPPORT teeth and tissue than that is not good underlying the denture base BASIC COMPONENTS OF RPD 1. Retainer SECONDARY  Abutment  Abutment a. Direct SUPPORT teeth teeth b. Indirect INDIRECT  None  Present REMOVABLE PARTIAL DENTURES 8  PROSTHODONTICS 2 2. Connector  Secondary abutment = indirect retainer a. Major are placed b. Minor TYPES OF DIRECT RETAINERS 3. Denture Base I. INTRACORONAL a. Resin  Vertical walls built INTO the crown of b. Metal the abutment  Retained by virtue of friction 4. Pontics  a.k.a. internal attachment, precision - Artificial teeth that replaces the attachment, key and keyway missing teeth “ porcelain*metal*  this can be casted then attached to 5. Other Parts the abutment  Proximal plates  Not usually used in distal extension  Clasp: under direct retainer  Tooth-tissue supported (based on  DISADVANTAGE OF INTRACORONAL support) RETAINERS  All resin, resin with wired clasp, resin  Prepared abutment and casting with casted clasp  Complicated clinical and lab  Resin with casted clasp (based on procedure material used)  Loss of frictional resistance due to  Kasi makapal yung clasp wear  Difficult to repair and replace  Least effective on short  RETAINERS teeth (possible that the entire A. DIRECT RETAINERS keyway will not fit)  Engages an abutment tooth to resist  Difficult to place within the displacement of the prosthesis away circumference of the from the basal seat tissue abutment (direct retainer must  Responsible for retention make contact with abutments as  Clasps or precision attachments much as possible)  Primary abutment = direct retainer are placed REMOVABLE PARTIAL DENTURES 9  PROSTHODONTICS 2 CLASP ASSEMBLY COMPONENT FUNCTION LOCATION PART REST Support Occlusal, Lingual, Incisal MINOR Stabilization/Bracin Proximal CONNECTOR g Surface II. EXTRACORONAL CLASP ARMS  Mechanical retention from the outer surface Reciprocal  Most widely used retainer Arm Reciprocation Apical  Clasp type retainer is the most common Portion of form used the Middle Retentive REQUIREMENTS OF CLASP ASSEMBLY Stabilization/Bracin Third Arm *should provide: g (located on the (Lingual o Retention shoulder apical surafce) o Reciprocation portion) and Buccal o Bracing Retention area with o Support  Clasp has two arms , one will be the flexible retentive (terminal end) teeth engagin g the undercut /gingival third *only the retentive teeth is in undercut REMOVABLE PARTIAL DENTURES 10  PROSTHODONTICS 2 Lower cost Strain on abutment teeth caused by: Shorter fabrication Improper tooth prep time Wrong clasp design Loss of tissue support under DE,DB (distal extension of denture base)  Retentive location: Buccal area with the Clasp can be unaesthetic retentive teeth engaging the undercut Caries may develop under clasp components  REST  Rounded triangular  To conform with the anatomy of the occlusal surface The clasp retained RPD with extracoronal DR (direct retainer) are used more frequently than the precision attachment RPD.  Precision cannot be altered Clasp Retained Advantage vs. Disadvantage ADVANTAGES DISADVANTAGES REMOVABLE PARTIAL DENTURES 11  PROSTHODONTICS 2  Buccal with the retentive teeth engaging the undercut (below survey 2. INFRABULGE CLASP line)  Arms originating from the mesh or o Retentive tip (located on the below the height of contour undercut only para flexible)  Reciprocal arm: middle third only 3. COMBINATION CLASP (located above or on the survey line  Combination of supra and itself) infrabulge  Retentive arm should be tapering to provide flexibility ( to prevent difficulty o HoC- greatest circumference, of inserting the denture) determined by survey line  Infrabulge *reciprocal arm = located lingual  Suprabulge 8retentive arm = located buccal and shoulder is TYPES OF EXTRACORONAL RETAINER 1. SUPRABULGE CLASP  Arms originates from occlusal, or above the height of contour (indicated by the survey line)  Andito si C class REMOVABLE PARTIAL DENTURES 12  PROSTHODONTICS 2  Combination B. INDIRECT RETAINERS  Resists rotational movement of the denture TYPES OF SUPRABULGE CLASP  Usually comes in the form of a rest 1. Circumferential Clasp  Used in tooth tissue supported 2. Ring Clasp  TYPES: 3. Multiple Clasp o Auxiliary occlusal rest (hindi siya 4. Half and Half Clasp part ng class assembly) 5. Reverse action Clasp o Cingulum rest 6. Embrasure Clasp o Incisal rest 7. Back action Clasp o Canine extension from occlusal rest 1. PRIMARY RETENTION  Abutments bearing the direct retainers (primary abutment) 2. SECONDARY RETENTION  Provided by the intimate relationship of TYPES OF INFRABULGE CLASP the minor connectors contact with the “rest proximal plate T(type of bar) guiding planes, denture bases- and 1. RPT major connectors with the underlying 2. RPI tissue. 3. RPY o How framework is manufactured 4. RP- MODIFIED T-BAR and designed 5. RP- MODIFIED Y-BAR  R - Rest  P - Proximal Plate  Last letter: type of bar  Direct Retainer: tooth 25, 26, 14  Indirect Retainer: tooth 24 REMOVABLE PARTIAL DENTURES 13  PROSTHODONTICS 2 FULCRUM LINE  Where the denture rotates so we can predict the rotation of RPD  An imaginary line passing through 2 primary abutments o Triangle: direct retainer o Red arrow = the attempt od denture to remove denture away from denture o Green arrow = movement of denture towards the tissue  Indirect retainer: would counteract the movement (square)  There is a possible movement bc it is distal extension  Bisect the fulcrum line, this is where you will put indirect retainer REMOVABLE PARTIAL DENTURES 14  PROSTHODONTICS 2 LOCATION OF MAJOR CONNECTOR  Free of movable tissues (for the border) o Frenum, Tongue  Impingement of gingival tissue should be avoided o Cause pain and damage to gingival tissues  Should have a gingival clearance of at least 4mm (lower), 6mm (upper)  Bony prominences should be avoided during placement and removal. o Bony prominence that may be present: Maxillary Tori, mandibular exostosis o Cannot place MC in bony prominences  Relief should be provided beneath a major connector to prevent its settling into areas of possible interference such as inoperable tori or elevated median palatal suture. o Relief: space In between tissue and metal as thick as pink wax, very thin. SEP 2 2021 (THURSDAY) o Reduce metal framework thickness if patient is in pain due to impingement (it will prone to CONNECTOR fracture) A. MAJOR CONNECTOR  Connects the part of the prosthesis located on CHARACTERISTICS OF MAJOR CONNECTORS: one side with those on the opposite side 1. Must be Rigid  Provides cross-arch stability to help resist the 2. Made from metal compatible with oral tissues (to avoid displacement of the denture by functional allergic reaction to soft tissue) stresses. 3. Does not interfere with and is not irritating to the tongue, As  Provides stability, just like a foundation thin as functionally as possible.  From the primary abutment to the other 4. Does not alter the lingual surface of mandibular lingual abutment on the opposite side sulcus or the palate  Choice of the major connector has a great 5. Covers no more tissue than is absolutely necessary impact in the design of the RPD. 6. Does not contribute to the entrapment of food: Should be  Should the major connector be flexible? NO, it well adapted to soft tissues. must be rigid to provide cross-arch stability.  Possible effect of major connector not being rigid can cause damage; periodontal damage, to the abutment, to the teeth and to the residual ridge  Should be made up of alloy that are compatible of oral tissues. MANDIBULAR MAJOR CONNECTORS A. Lingual Bar REMOVABLE PARTIAL DENTURES 15  PROSTHODONTICS 2  Commonly used (first option) together with F. Labial Bar linguoplate bar.  Thickness should be 4mm  Significant: no minimum of 8mm clearance you cannot use the lingual bar  If it will hit the frenum then choose other connectors B. Linguoplate  Very rarely use due to esthetic  Adapted in the linguo surfaces Tissue Clearance: Distance from the metal to the cervical  Scalloped shape area.  For high lingual frenum Maxillary: 4mm Mandibular:6mm C. Sublingual Bar Thickness of Lingual Bar: Minimum of 4mm  Located much lower almost at the frenum area D. Lingual bar with cingulum bar E. Cingulum bar (continuous bar) MAXILLARY MAJOR CONNECTOR A. Single palatal strap REMOVABLE PARTIAL DENTURES 16  PROSTHODONTICS 2 SAMPLE EXAM: B. Combination anterior and posterior palatal strap-type connector (AP STRAP) Major Connector: Single Palatal Bar How many direct retainer: 4 Do you have indirect retainer? Yes Where is located? 33 C. Palatal plate-type connector Type? Cingulum Rest ( Refrain using cingulum rest in mandibular) D. U-shaped palatal connector Major Connector: AP Strap How many direct retainer? 2 Type? Extracoronal What type of extracoronal in tooth 25: Infrabulge Type of Infrabulge: RPI Dimensions of AP strap in lateral: 7-9mm extended until the posterior area Remaining Tooth: 13,14, 15,16,17,26,27 rarely use; no cross arch stabilisation and it is flexible E. Single Palatal Bar MINOR CONNECTOR  4mm only greater than that would be considered as strap  Connecting link between major connector base of a RPD and the other component of a prosthesis F. Anterior-posterior palatal bars  It retains the denture base  It contacts the guiding planes (proximal plates) REMOVABLE PARTIAL DENTURES 17  PROSTHODONTICS 2 FUNCTIONS OF THE MINOR CONNECTOR 1. Joins the part of the denture to the major connector 2. Transfers the stresses to the abutments (Prosthesis to abutment function) Prosthesis To Abutment FXN – 50:46  Supported by horizontal 3. Transfers the effect of the retainers, rests, and stabilizing components throughout the prosthesis. (Abutment to prosthesis function) Other Types of Minor Connector Horizontal A. Ladder Type  Should have no sharp angles  Extends just a little on the buccal side of the crest of the ridge  For distal ecxtension  Stress concentrated to the abutment area. o MAX: Extends up to the hamular notch The effect of the minor connector o MAN: Extends up to 2/3 length of edentulous area  Thus forces applied on one portion of the denture may be resisted by other components placed elsewhere in the arch for that purpose. FORM AND LOCATION OF MINOR CONNECTORS  VERTICAL MINOR CONNECTORS o Should have sufficient bulk to be rigid o Located on embrasure area o Should conform to the interdental embrasure o Covers a little gingiva as possible o Thickest towards the lingual surface and tapering towards the contact area. B. MESH o Should have no sharp angles - Less retention for the acrylic if openings are small o Must have at least 5mm distance between 2 - A.k.a Lattice Gridwork minor connector o Must meet the MC at right angle REMOVABLE PARTIAL DENTURES 18  PROSTHODONTICS 2 Factors to consider in pontic selection:  Shade o Use natural teeth as the basis  Mould o Based on the shape of the face of the patient  Metal pontics that is adapted on metal bases. DENTURE BASE 2 TYPES OTHER PARTS a. Acrylic A. PROXIMAL PLATES b. Metal  Thickest towards the cervical area FUNCTION:  Should contact the guiding plane of the abutment  Supports artificial teeth  Triangular in shape  Receives the funcitonal stresses from occlusion  Height is 2/3 of the length of the crown (at the  Transfers functional forces to oral structures greatest circumference of the tooth)  Aids to the cosmetic effects of the denture  Width, ¼ intercuspal distance  Stimulation of underlying tissue of residual ridge REQUIREMENTS OF AN IDEAL DENTURE BASE  Accuracy of adaptation  Dense, non-irritating surface, with good finish  Thermal conductivity  Easily kept clean  Has sufficient stregth B. TISSUE STOPS  Esthetic acceptability  Integral part of the minor connector  Has potential for future relining  Low initial cost PONTICS REMOVABLE PARTIAL DENTURES 19  PROSTHODONTICS 2 Function:  Provides stabillity to the denture framework during processing  Prevents distortion of framework during processing  Can engage buccal and lingual stops for stability. C. FINISH LINES  Marks the end of the denture base  Junction between the minor connector and the major connector TYPES: a. Internal Finish Line- Contact of metal/ acrylic to tissue b. External Finish Line- Acrylic to metal REMOVABLE PARTIAL DENTURES 20