The University of Western Australia | Oral Health Centre of Western Australia Removable partial denture Survey and Design Dr/ Marrwa Ibrahim  The University of Western Australia Oral Health Centre of Western Australia #### Course Presentation - Removable partial denture - Survey and Design - Dr. Marrwa Ibrahim Close-up photograph of a white architectural structure featuring rows of circular holes. The holes reveal colorful interiors in red, yellow, green, and blue, creating a patterned visual effect relevant to the aesthetic design context of removable partial dentures. # **KENNEDY CLASSIFICATION + MODIFICATIONS** | Class | Definition | | :--- | :--- | | **Class I** | Bilateral edentulous areas located posterior to all remaining teeth. | | **Class II** | Unilateral edentulous area located posterior to all remaining teeth. | | **Class III** | Unilateral edentulous area bounded by anterior and posterior natural teeth. | | **Class IV** | A single edentulous area, but bilateral bordered by natural teeth, (crossing the midline) located anterior to remaining teeth. |     #### Kennedy Classification Definitions - **Class I**: Bilateral edentulous areas located posterior to all remaining teeth. - **Class II**: Unilateral edentulous area located posterior to all remaining teeth. - **Class III**: Unilateral edentulous area bounded by anterior and posterior natural teeth. - **Class IV**: A single edentulous area, but bilateral bordered by natural teeth (crossing the midline), located anterior to remaining teeth. Clinical photograph of a dental cast demonstrating Class I Kennedy classification: bilateral edentulous areas located posterior to all remaining teeth. Clinical photograph of a dental cast demonstrating Class II Kennedy classification: unilateral edentulous area located posterior to all remaining teeth. Clinical photograph of a dental cast demonstrating Class III Kennedy classification: unilateral edentulous area bounded by anterior and posterior natural teeth. Clinical photograph of a dental cast demonstrating Class IV Kennedy classification: single edentulous area crossing the midline, bounded by natural teeth, located anterior to remaining teeth. KENNEDY CLASSIFICATION + **MODIFICATIONS** Each additional edentulous area (not each missing teeth) is referred as a modification space.  #### Modification Spaces Each additional edentulous area is referred to as a modification space. Note that the classification is based on the number of additional areas, not the number of individual missing teeth. A composite figure displaying four dental casts illustrating edentulous areas for Kennedy Classification modifications. The top-left panel (labeled E) shows a mandibular cast with missing posterior teeth on the right side. The top-right panel (labeled F) displays a maxillary cast with missing posterior teeth on both sides. The bottom-left panel (labeled G) features a mandibular cast with multiple missing teeth and edentulous spaces. The bottom-right panel (labeled H) presents a maxillary cast with significant posterior tooth loss. These visuals demonstrate different modification spaces as described in the accompanying text. Applegate’s rules applied to the Kennedy classification 1. The classification should be **determined after all extractions** (if applicable) 2. If the **third molar is missing** and **not to be replaced**, it is **not considered in the classification** 3. If the **third molar is present** and **is an abutment**, it is **considered in the classification** 4. If the **second molar is missing** and is **not to be replaced**, it is **not considered in the classification** 5. The **most posterior edentulous area**(s) always **determines the classification** 6. **Edentulous areas other** than those determining the classification are **referred as ‘modification’** and are designated by their number 7. The **extent of the modification is not considered**, only the **number of additional edentulous areas** 8. THERE IS **no modification in Class IV** 1. The classification should be determined after all extractions (if applicable). 2. If the third molar is missing and not to be replaced, it is not considered in the classification. 3. If the third molar is present and is an abutment, it is considered in the classification. 4. If the second molar is missing and is not to be replaced, it is not considered in the classification. 5. The most posterior edentulous area(s) always determines the classification. 6. Edentulous areas other than those determining the classification are referred to as 'modification' and are designated by their number. 7. The extent of the modification is not considered, only the number of additional edentulous areas. 8. There is no modification in Class IV. # **Surveying the Diagnostic Cast** 1- To determine the most desirable path of placement 2- To identify proximal tooth surfaces that are or need to be made parallel so that they act as guiding planes 3- To locate and measure areas of the teeth that may be used for retention 4- To determine whether teeth and bony areas are area of interference 5- To determine the most suitable path of placement that provide the best esthetic advantage 6- To permit accurate charting of the mouth preparations to be made 7- To record the cast position in relation to the selected path of placement for future reference: The diagnostic cast is surveyed to achieve the following clinical and technical goals: 1. Determine the most desirable path of placement. 2. Identify proximal tooth surfaces that are or need to be made parallel so that they act as guiding planes. 3. Locate and measure areas of the teeth that may be used for retention. 4. Determine whether teeth and bony areas act as areas of interference. 5. Determine the most suitable path of placement that provides the best esthetic advantage. 6. Permit accurate charting of the mouth preparations to be made. 7. Record the cast position in relation to the selected path of placement for future reference. **PARTS OF A DENTAL SURVEYOR** **1. Surveying Table (Cast holder):** it allows the cast to be oriented at various tilts and to be fixed along one of these planes through a ball and socket joint.   #### Surveying Table (Cast Holder) The surveying table allows the cast to be oriented at various tilts and to be fixed along one of these planes through a ball and socket joint. Clinical photo of a dental surveyor's Surveying Table (Cast holder). The image shows the metallic base and ball-and-socket joint mechanism without a cast attached. Clinical photo demonstrating the use of the Surveying Table. A white dental cast is mounted on the device, illustrating how it allows the cast to be oriented at various tilts via the ball and socket joint as described in the text. # **PARTS OF A DENTAL SURVEYOR** **2. Surveying Arm:** **** a vertical arm used to analyse the parallelism of various axial cast surfaces. The height of the arm can be adjusted, and it contains a holder so that several surveying tools may be attached and used.  #### Surveying Arm The surveying arm is a vertical arm used to analyze the parallelism of various axial cast surfaces. The height of the arm can be adjusted, and it contains a holder so that several surveying tools may be attached and used. Photo of a dental surveyor with the vertical Surveying Arm circled in blue. The image demonstrates the tool described in the text as being used to analyze parallelism and containing a holder for surveying tools. **PARTS OF A DENTAL SURVEYOR** **3. Surveying Tools:** **a. Analyzing Rod** A thin straight metal rod used to analyze contours and undercuts in the cast. It determines relative parallelism of axial surfaces. *Analyzing rod* *Triangular space* **b. Carbon Marker** Rod like pencil lead that is used to mark the location of the height of contour on a dental cast. *Sheath* *Lead* **c. Undercut gauges** Identify the position of desired undercuts on casts **Size 1:** 0.25 mm/ 0.01" - CoCr alloys **Size 2:** 0.50 mm/ 0.02" - Gold alloy **Size 3:** 0.75 mm/ 0.03"- Wrought wire **d. Surveyor blade:** Trim stone tooth to adjust the height of contour to the desirable position.      #### Surveying Tools - **Analyzing Rod** A thin straight metal rod used to analyze contours and undercuts in the cast. It determines the relative parallelism of axial surfaces and identifies the triangular space. - **Carbon Marker** A rod-like pencil lead, often held in a sheath, used to mark the location of the height of contour on a dental cast. - **Undercut Gauges** Used to identify the position of desired undercuts on casts. They are available in specific sizes for different materials: - **Size 1:** 0.25 mm (0.01") - Used for Cobalt-Chromium (CoCr) alloys. - **Size 2:** 0.50 mm (0.02") - Used for Gold alloys. - **Size 3:** 0.75 mm (0.03") - Used for Wrought wire. - **Surveyor Blade** Used to trim the stone tooth to adjust the height of contour to the desirable position. Line drawing diagram illustrating the 'Analyzing Rod' in use. It shows a vertical rod labeled 'Analyzing rod' placed against a tooth outline to identify a 'Triangular space', demonstrating how it analyzes contours and undercuts. Diagram showing the components of the 'Carbon Marker'. It displays a cylindrical object labeled 'Sheath' and a thin rod labeled 'Lead', representing the pencil-like lead used to mark the height of contour. Photograph or realistic rendering of three distinct metal instruments identified as 'Undercut gauges' (Sizes 1, 2, and 3). The tools are shown with varying thicknesses corresponding to their specific measurements for CoCr alloys, Gold alloy, and Wrought wire respectively. Small line drawing diagram showing an undercut gauge placed against a tooth outline, visually demonstrating the application described in the text for identifying desired undercuts on casts. Diagram illustrating the 'Surveyor blade'. It depicts a black cutting tool with a curved tip positioned next to a grey rectangular block, representing the action of trimming stone teeth to adjust the height of contour. **DENTAL SURVEY** 1 - Preliminary assessment of the cast 2 - Selecting the path of insertion (POI) of the RPD 3 – Initial assessment of undercuts 4 – Drawing the height of contour 5 - Survey lines of soft tissues 6 - Tripodization of the diagnostic cast 7 - Identification of retentive undercuts 8 - Drawing the metal framework 9 - Adjusting the height of contour 10 - Creating guiding planes 11– Redraw the lines erased after changes on tooth contour The dental survey procedure involves the following sequential steps: 1. Preliminary assessment of the cast 2. Selecting the path of insertion (POI) of the RPD 3. Initial assessment of undercuts 4. Drawing the height of contour 5. Survey lines of soft tissues 6. Tripodization of the diagnostic cast 7. Identification of retentive undercuts 8. Drawing the metal framework 9. Adjusting the height of contour 10. Creating guiding planes 11. Redraw the lines erased after changes on tooth contour # Initiate dental survey of maxillary model ## Task Initiate dental survey of maxillary model ## Preliminary assessment 1) Kennedy Classification (modifications): _________________________ 2) Identify the fulcrum lines (tooth number): _________________________ 3) Potential rest seat locations (tooth number, surface M/D/L): _________________________ 4) Indirect retention (tooth number, surface M/D/L): _________________________ 5) Find the initial POI (Perpendicular to the occlusal plane) 6) Initial assessment of undercuts: verify if the POI is adequate 7) Draw the height of contour on abutment teeth 8) Tripodization of the diagnostic cast 8) Identification of retentive undercuts (retentive clasp position) ## Self-assessment | Self-assessment | 2 | 1 | 0 | | ---|---|---|---|---| | **POI** | | | | | | **Height of contour** | | | | | | **Tripodization** | | | | | | **Retentive clasp tip position** | | | | |  #### Task Initiate dental survey of maxillary model #### Preliminary Assessment Data 1. Kennedy Classification (modifications): _________________________ 2. Identify the fulcrum lines (tooth number): _________________________ 3. Potential rest seat locations (tooth number, surface M/D/L): _________________________ 4. Indirect retention (tooth number, surface M/D/L): _________________________ 5. Find the initial POI (Perpendicular to the occlusal plane) 6. Initial assessment of undercuts: verify if the POI is adequate 7. Draw the height of contour on abutment teeth 8. Tripodization of the diagnostic cast 9. Identification of retentive undercuts (retentive clasp position) #### Self-Assessment Rubric | Self-assessment | 2 | 1 | 0 | | :--- | :--- | :--- | :--- | | **POI** | | | | | **Height of contour** | | | | | **Tripodization** | | | | | **Retentive clasp tip position** | | | | Self-assessment table with columns for 'Self-assessment' and numeric ratings (2, 1, 0), plus a 'Tutor grade' column. Rows include: POI, Height of contour, Tripodization, Retentive clasp tip position. **DENTAL SURVEY** 1 - Preliminary assessment of the cast *Classify the edentulous arch *Identify fulcrum lines *Define potential rest seat locations  #### Preliminary Assessment Steps - Classify the edentulous arch - Identify fulcrum lines - Define potential rest seat locations Anatomical diagram of the upper edentulous dental arch showing five different configurations with overlaid lines. The top row shows three variations: a diagonal line crossing the arch (left), a longer diagonal line extending from posterior to anterior (center), and a horizontal line across the mid-arch (right). The bottom row shows two more complex configurations: one with multiple intersecting lines forming an X-shape and another with parallel vertical lines and a horizontal crossbar. These diagrams illustrate fulcrum lines and potential rest seat locations for removable partial dentures, as referenced in the OCR text. **DENTAL SURVEY** **2 - Selecting the path of insertion (POI) of the RPD** * The initial POI will be perpendicular to the occlusal plane. * Select three points in the model that define the occlusal plane. **Maxilla:** Two posterior points, mesial marginal ridge of 1st or 2nd molars in each quadrant. One anterior point: bellow the interproximal contact point between 11 and 21 (near the cingulum). **Mandible:** Two posterior points, mesial marginal ridge of 1st or 2nd molars in each quadrant. One anterior point: incisal edge of 31 or 41.   #### Path of Insertion Selection Criteria - The initial POI will be perpendicular to the occlusal plane. - Select three points in the model that define the occlusal plane. #### Anatomical Reference Points - **Maxilla:** Two posterior points (mesial marginal ridge of 1st or 2nd molars in each quadrant). One anterior point (below the interproximal contact point between 11 and 21, near the cingulum). - **Mandible:** Two posterior points (mesial marginal ridge of 1st or 2nd molars in each quadrant). One anterior point (incisal edge of 31 or 41). Clinical photograph of a dental cast showing the maxillary arch. A red dot marks the anterior point (near the cingulum between teeth 11 and 21), and two other red dots mark posterior points on the mesial marginal ridges of molars in each quadrant. Clinical photograph of a dental cast showing the mandibular arch from an occlusal view. Red dots indicate the selected points: one anterior point on the incisal edge of tooth 31 or 41, and two posterior points on the mesial marginal ridges of molars in each quadrant. **DENTAL SURVEY** 2 - Selecting the path of insertion (POI) of the RPD * Place the cast on the surveyor table and orient the plane of occlusion relatively horizontal. * Using the Analysing Rod, adjust the inclination of the Surveying Table and the vertical position of the Surveying Arm until the three points coincide with the tip of the analysing rod without changing the vertical arm position.     #### Surveyor Table Adjustment - Place the cast on the surveyor table and orient the plane of occlusion relatively horizontal. - Using the Analysing Rod, adjust the inclination of the Surveying Table and the vertical position of the Surveying Arm until the three points coincide with the tip of the analysing rod without changing the vertical arm position. Clinical photo of a maxillary dental cast showing the upper arch. Red dots mark specific points on the buccal cusps of posterior teeth, likely indicating reference points for surveying. Clinical photo of a mandibular dental cast showing the lower arch. Red dots mark corresponding points on the lingual cusps of posterior teeth, demonstrating the selection of three points for establishing the path of insertion. Clinical photo of a third dental cast (likely maxillary) with red dots marking the same anatomical regions as the other casts, illustrating consistency in point selection across different cases. Schematic diagram illustrating the use of a wax rim to simulate molar anatomy. The caption 'Use wax rim to simulate the molar' explains that this step is necessary when the patient's posterior teeth are missing or worn down, allowing the surveyor to establish the correct occlusal plane and path of insertion. # **Dental Survey of maxillary cast** --- 1 - Preliminary assessment of the cast 2 - Selecting the path of insertion (POI) of the RPD  1. Preliminary assessment of the cast 2. Selecting the path of insertion (POI) of the RPD Clinical photo demonstrating the setup for a dental survey of a maxillary cast. The image shows a dental cast mounted on an articulator base with a metal casting ring or clasp assembly attached. Above it is a dental surveyor instrument with its indicator arm positioned to analyze the path of insertion (POI) and guide plane. **DENTAL SURVEY** **3 – Initial assessment of undercuts** * Place the analysing rod against the axial surface of proposed abutment teeth. * The tip of the rod should be at the level of the free gingival margin. * If the height of contour is located in an unfavourable position (near the occlusal third or near the gingival margin) or if there is no undercut, the incline of the cast has to be changed to obtain a more favourable retention area. * Soft tissues interferences (i.e., mandibular tori, residual ridge undercuts) also need to be avoided by modifying the path of insertion.  #### Analyzing Rod Application - Place the analysing rod against the axial surface of proposed abutment teeth. - The tip of the rod should be at the level of the free gingival margin. #### Corrective Actions - If the height of contour is located in an unfavourable position (near the occlusal third or near the gingival margin) or if there is no undercut, the incline of the cast has to be changed to obtain a more favourable retention area. - Soft tissues interferences (i.e., mandibular tori, residual ridge undercuts) also need to be avoided by modifying the path of insertion. Line drawing diagram demonstrating the placement of a dental analyzing rod against an abutment tooth. The image shows a vertical black tool labeled 'Analyzing rod' positioned on the axial surface of a tooth outline. A red bracket highlights the specific area where the rod contacts the tooth contour, labeled 'Undercut', illustrating the concept of undercut assessment during the initial survey. **DENTAL SURVEY** **4 – Drawing the height of contour** Place the carbon marker against the axial surface of proposed abutment teeth. The tip of the carbon should be placed near the level of the free gingival margin. Mark the height of contour around each abutment teeth. The position of the height of contour can be changed again by tilting the cast if necessary.   #### Marking the Height of Contour - Place the carbon marker against the axial surface of proposed abutment teeth. - The tip of the carbon should be placed near the level of the free gingival margin. - Mark the height of contour around each abutment teeth. #### Adjustments - The position of the height of contour can be changed again by tilting the cast if necessary. Diagram illustrating the 'Drawing the height of contour' procedure on dental casts. It displays three labeled panels: 'Ideal' (0°), 'Too high' (-10), and 'Too low' (+10). Each panel shows a carbon marker placed against the axial surface of teeth to mark the height of contour relative to the free gingival margin. Photo showing a dental surveyor instrument mounted on a base with a cast. The text next to it explains that the position of the height of contour can be changed by tilting the cast if necessary. **Dental Survey of maxillary cast** **3 – Initial assessment of undercuts** **4 – Drawing the height of contour**  3. Initial assessment of undercuts 4. Drawing the height of contour Clinical procedure photo demonstrating the 'Dental Survey of maxillary cast'. The image shows a white plaster dental cast (maxilla) mounted on an articulator. A metal surveyor instrument with a vertical pointer is positioned directly above the teeth, illustrating the physical process of assessing undercuts and determining the height of contour. **DENTAL SURVEY** 5 - Survey lines of soft tissues  5. Survey lines of soft tissues Line drawing diagram illustrating the survey line of soft tissues. It shows a simplified outline of a human head and neck with a vertical black bar representing the surveyor's indicator or parallel plane positioned along the right side of the mandible/neck area. An arrow points from the vertical bar towards the tissue contour, indicating the measurement path or contact point as described in the OCR text 'Survey lines of soft tissues'. # DENTAL SURVEY ## 6 - Tripodization of the diagnostic cast Tripodization is completed after the ideal path of insertion has been established. With the vertical arm of the surveyor **locked**, three widespread tissue points (two posterior and one anterior) are selected in relatively noncritical areas. *(Maxilla: **palate**; Mandible: **lingual side of alveolar ridge**)* **Reason:** to facilitate the repositioning of the same cast or a different one in the established ideal path of insertion.  #### Tripodization Procedure Tripodization is completed after the ideal path of insertion has been established. - With the vertical arm of the surveyor **locked**, three widespread tissue points (two posterior and one anterior) are selected in relatively noncritical areas. - **Reference Areas:** - Maxilla: Palate - Mandible: Lingual side of alveolar ridge **Reason:** To facilitate the repositioning of the same cast or a different one in the established ideal path of insertion. Clinical procedure photo demonstrating tripodization of a diagnostic dental cast. The image shows a maxillary plaster cast mounted on an articulator with the vertical arm of a dental surveyor locked in position and pointing downwards towards the palate area. This visual demonstrates the step where three widespread tissue points are selected to facilitate repositioning. # **DENTAL SURVEY** ## **7 - Identification of retentive undercuts:** ➢ where the tip of the retentive arm will be placed. ➢ Use 0.25 mm gauge (0.01'') ➢ Bring the vertical shaft of the gauge in contact with the tooth and then moving the surveying arm up or down until the terminal lip touches the tooth surface. ➢ Repeat the steps for all retentive arms.  #### Retentive Undercut Identification - Identify where the tip of the retentive arm will be placed. - Use 0.25 mm gauge (0.01''). - Bring the vertical shaft of the gauge in contact with the tooth and then move the surveying arm up or down until the terminal lip touches the tooth surface. - Repeat the steps for all retentive arms. Clinical photo demonstrating the dental survey procedure. It shows a close-up of a metal surveying gauge (specifically the vertical shaft and terminal lip) being applied to the buccal surface of a tooth model. The image illustrates the step where the terminal lip touches the tooth surface to identify retentive undercuts. **Dental Survey of maxillary cast** 5 - Survey lines of soft tissues 6 - Tripodization of the diagnostic cast 7 - Identification of retentive undercuts:  5. Survey lines of soft tissues 6. Tripodization of the diagnostic cast 7. Identification of retentive undercuts Clinical photograph demonstrating the dental survey of a maxillary cast. The image shows a white diagnostic dental model (upper jaw) mounted on an articulator base with a surveyor instrument positioned directly above it. The probe tip of the surveyor is aligned with a specific tooth on the cast, illustrating step 6 'Tripodization of the diagnostic cast' or step 7 'Identification of retentive undercuts' mentioned in the OCR text. **DENTAL SURVEY** **8 - Drawing the metal framework** 1) **REST SEATS:** * Intercalated edentulous area: adjacent to the edentulous area * **Free-end edentulous area:** not immediately adjacent to the saddle * Include indirect retainers 2) **GRIDS:** * Free-end saddle—2/3 of the bearing area  #### Rest Seats - **Intercalated edentulous area:** Adjacent to the edentulous area. - **Free-end edentulous area:** Not immediately adjacent to the saddle. - Include indirect retainers. #### Grids - **Free-end saddle:** 2/3 of the bearing area. Labeled diagram of a maxillary dental cast illustrating the design of a metal framework for a partial denture. The image shows two distinct areas outlined in red: the 'Free-end edentulous area' on the left side and the 'Intercalated edentulous area' on the right side. Black rectangular outlines represent rest seats within these areas. A text label '2/3' points to the black rectangle in the free-end saddle region, indicating that the grid should cover 2/3 of the bearing area. **DENTAL SURVEY** **8 - Drawing the metal framework** **3) CLASPS:** retention arm and reciprocal arm **Simple circumferential:** rest adjacent to edentulous area **Reverse circumferential:** rest opposing to edentulous area. It needs a proximal plate. **Ring clasp:** rest on both sides of the abutment **Embrasure clasp:** between abutments, indirect retainer **T-clasp:** Retention arm cross gingival margin at 90° **Modified T-clasp:** to avoid significant undercuts **I-clasp:** cross perpendicular the gingival margin. **RPI-clasp:** rest, proximal plate and I bar (no reciprocal arm)         #### Clasp Types and Applications - **Simple circumferential:** Rest adjacent to edentulous area. - **Reverse circumferential:** Rest opposing to edentulous area; requires a proximal plate. - **Ring clasp:** Rest on both sides of the abutment. - **Embrasure clasp:** Placed between abutments; acts as an indirect retainer. - **T-clasp:** Retention arm crosses gingival margin at 90°. - **Modified T-clasp:** Used to avoid significant undercuts. - **I-clasp:** Crosses perpendicular to the gingival margin. - **RPI-clasp:** Consists of a rest, proximal plate, and I-bar (no reciprocal arm). Clinical photo of a Simple circumferential clasp. The metal framework rests adjacent to the edentulous area. Clinical photo of a Reverse circumferential clasp. The rest opposes the edentulous area and includes a proximal plate. Diagram illustrating a Ring clasp. The visual shows the clasp resting on both sides of the abutment tooth. Diagram of an Embrasure clasp positioned between two abutments, functioning as an indirect retainer. Clinical photo of a T-clasp. The retention arm crosses the gingival margin at a 90° angle. Clinical photo of a Modified T-clasp designed to avoid significant undercuts. Clinical photo of an I-clasp. The component crosses perpendicular to the gingival margin. Diagram of an RPI-clasp system. It illustrates the Rest (mesial), Proximal plate, and I-bar, noting that this configuration has no reciprocal arm. **DENTAL SURVEY** **8 - Drawing the metal framework** **4) MAJOR CONNECTOR:** Mandible : 3-4 mm from the gingival margin and 5 mm of width Maxilla : 5-6 mm from the gingival margin and 8 mm of width **TYPES:** | | **Maxilla** | **Mandible** | |---|---|---| | | Single palatal strap | Lingual bar | | | Anterior-posterior palatal strap | Lingual plate | | | U-shaped palatal connector | Cingulum bar | | | Broad palatal strap or Palatal plate | Double lingual bar (Kennedy bar) | | | Single palatal bar | Sublingual bar | | | Anterior-posterior palatal bar | |   #### Major Connector Dimensions - **Mandible:** 3-4 mm from the gingival margin and 5 mm of width. - **Maxilla:** 5-6 mm from the gingival margin and 8 mm of width. #### Major Connector Types | Maxilla | Mandible | | :--- | :--- | | Single palatal strap | Lingual bar | | Anterior-posterior palatal strap | Lingual plate | | U-shaped palatal connector | Cingulum bar | | Broad palatal strap or Palatal plate | Double lingual bar (Kennedy bar) | | Single palatal bar | Sublingual bar | | Anterior-posterior palatal bar | | Step-by-step procedure image demonstrating the drawing of a metal framework for a major connector. The sequence shows an initial outline on a cast (left), progressing to a detailed design with specific measurements marked in red (middle). The rightmost panel provides a close-up cross-sectional view illustrating vertical dimensions: 3-4 mm from the gingival margin and a total width of 5 mm. A classification table listing types of Major Connectors categorized by arch. Columns are 'Maxilla' and 'Mandible'. Maxilla types include Single palatal strap, Anterior-posterior palatal strap, U-shaped palatal connector, Broad palatal strap or Palatal plate, Single palatal bar, and Anterior-posterior palatal bar. Mandible types include Lingual bar, Lingual plate, Cingulum bar, Double lingual bar (Kennedy bar), and Sublingual bar. **DENTAL SURVEY** 8 - Drawing the metal framework 5) **MINOR CONNECTORS:** Join the remaining components of a RPD to the major connector   #### Minor Connectors Minor connectors join the remaining components of a Removable Partial Denture (RPD) to the major connector. Clinical photo showing a close-up view of a metallic dental minor connector (clasp assembly) joining the retainer component to the major framework bar on a dental cast. Clinical photo demonstrating minor connectors on an RPD. Red arrows point specifically to the minor connectors that join the clasp assemblies to the central metal framework bar. **Dental Survey of maxillary cast** **8 - Drawing the metal framework**  8. Drawing the metal framework Clinical photo of a maxillary dental cast (upper jaw model) with visible teeth and marked survey lines on the palate. The image is associated with the text 'Dental Survey of maxillary cast' and '8 - Drawing the metal framework', indicating it demonstrates the stage of preparing for a removable partial denture by marking reference points. **DENTAL SURVEY** 9 - Adjusting the height of contour: - All reciprocal arms need to be above the height of contour - 1/3 of the retention arm should be in undercut - Use surveyor blade to trim the plaster tooth surface     #### Height of Contour Adjustments - All reciprocal arms must be positioned above the height of contour. - 1/3 of the retention arm should be located in the undercut. - Use a surveyor blade to trim the plaster tooth surface. Diagram of a dental tooth model showing the 'Retention arm' positioned to engage the undercut area, indicated by dotted lines representing the path of insertion. Diagram of a dental tooth model showing the 'Reciprocal arm', which is depicted as being positioned above the height of contour line (dotted), consistent with the text instruction that reciprocal arms must be above this level. Clinical photograph demonstrating the use of a surveyor blade trimming the plaster tooth surface. The image shows the instrument in action on the cast material. Figure illustrating the adjustment of the height of contour. It compares the 'Original height of contour' (red dashed line) with the 'New height of contour' (solid black line) after the surveyor blade has been used to trim the plaster surface. **DENTAL SURVEY** **10 - Creating guiding planes** Use surveyor blade | Carbon marking | Appearance on the surveyor | | :--- | :--- | | **Correct** | | | Wrong (too thin) | |  #### Guiding Plane Creation Use a surveyor blade to create guiding planes. | Carbon marking | Appearance on the surveyor | | :--- | :--- | | **Correct** | [Visual representation] | | **Wrong (too thin)** | [Visual representation] | Labelled diagram demonstrating the use of a surveyor blade for creating guiding planes. The visual is split into two rows comparing 'Correct' versus 'Wrong (too thin)' outcomes. The left column shows 'Carbon marking' on a tooth model with a grey shaded band representing the depth of cut. The right column shows the corresponding 'Appearance on the surveyor,' depicting the carbon line against the vertical blade edge. The top row illustrates a thick, correct carbon transfer, while the bottom row shows an insufficiently thin line indicating an error in procedure. **DENTAL SURVEY** 11 – Redraw the lines erased after changes on tooth contour 11. Redraw the lines erased after changes on tooth contour **Dental Survey of maxillary cast** 9 - Adjusting the height of contour 10 - Creating guiding planes 11 – Redraw the lines erased after changes on tooth contour  9. Adjusting the height of contour 10. Creating guiding planes 11. Redraw the lines erased after changes on tooth contour Clinical procedure image showing a dental surveying tool (labeled 'OPTEC 2') being used on a maxillary cast mounted in a dental articulator. The tool is positioned over the teeth to adjust height of contour or create guiding planes, as described by the OCR text listing steps 9, 10, and 11. # **Rests and Rest Seats:** ### **Rest:** A rigid component of a removable partial denture which rests in a recessed preparation on the occlusal, lingual or incisal surface of a tooth to provide vertical support for the denture. Although a rest is a component of a direct retainer (retentive unit, clasp assembly), the rest itself is classified as a supporting element due to the nature of its function. #### Rest A rigid component of a removable partial denture which rests in a recessed preparation on the occlusal, lingual or incisal surface of a tooth to provide vertical support for the denture. Although a rest is a component of a direct retainer (retentive unit, clasp assembly), the rest itself is classified as a supporting element due to the nature of its function. # **Rests and Rest Seats:** **Rest Seat:** A portion of a tooth selected and prepared to receive an occlusal, incisal or lingual rest. **Armamentarium:** ■ Spherical diamond bur (large diameter) ■ tapered round end bur ■ Material for composite restorations #### Rest Seat A portion of a tooth selected and prepared to receive an occlusal, incisal or lingual rest. #### Armamentarium - Spherical diamond bur (large diameter) - Tapered round end bur - Material for composite restorations # **Occlusal rest seat** Prepared on the occlusal surface of a bicuspid or molar. preparations are entirely in enamel. Preparation should have a smooth flowing outline form (no sharp line angles). ➢ Rounded triangular shape, base facing the proximal surface at the marginal ridge, and the apex toward the center of the occlusal surface ➢ Bucco-lingually: ½ inter-cusp distance (approximately one third the bucco-lingual width of the tooth. ➢ Mesio-distally: equal or slightly larger than B/L size    #### General Characteristics - Prepared on the occlusal surface of a bicuspid or molar. - Preparations are entirely in enamel. - Preparation should have a smooth flowing outline form (no sharp line angles). #### Dimensions and Shape - Rounded triangular shape, base facing the proximal surface at the marginal ridge, and the apex toward the center of the occlusal surface. - Bucco-lingually: 1/2 inter-cusp distance (approximately one third the bucco-lingual width of the tooth). - Mesio-distally: Equal or slightly larger than B/L size. Schematic diagram of a tooth occlusal view showing an occlusal rest seat preparation in red. Includes dimensional annotations: vertical height (y) and bucco-lingual width (w), illustrating the rounded triangular shape with base toward the proximal surface. Second schematic diagram of a tooth occlusal view with the same occlusal rest seat preparation highlighted in red. Shows detailed dimension lines for height (y) and bucco-lingual width (w), reinforcing proportional guidelines for preparation size. Line drawing of a molar occlusal surface with a black-shaded area indicating the occlusal rest seat location. Adjacent to it is a vertical scale bar labeled '1/3', visually representing that the bucco-lingual dimension should be approximately one-third of the total bucco-lingual width of the tooth. **Occlusal rest seat** The marginal ridge must be lowered and rounded to permit a sufficient bulk of metal to prevent fracture of the rest from the minor connector (1 to 1.5 mm) Concaved floor, rounded (spoon like shape) Slightly inclined apically (less than 90°) Tooth reduction: 1-1.5mm occ-gingival, taper to the center till only 0.5mm reduction #### Structural Requirements - The marginal ridge must be lowered and rounded to permit a sufficient bulk of metal to prevent fracture of the rest from the minor connector (1 to 1.5 mm). - Concaved floor, rounded (spoon like shape). - Slightly inclined apically (less than 90°). #### Tooth Reduction - 1-1.5mm occluso-gingival reduction. - Taper to the center until only 0.5mm reduction. **Occlusal rest seat** ✓ The floor of the rest seat should be inclined towards the centre of the tooth, so that the angle formed by the rest and the minor connector should be less than 90°. This helps to direct the occlusal forces along the long axis of the tooth. ✓ You can test to see if a rest seat is ‘positive’ (less than 90° by trying to slide an explorer tip off the rest seat. ✓ An angle of more than 90° fails to transmit the occlusal forces along the long axis of the tooth and permits movement of the clasp assembly away from the abutment and orthodontic movement of the tooth.  #### Floor Inclination and Force Distribution - The floor of the rest seat should be inclined towards the centre of the tooth, so that the angle formed by the rest and the minor connector should be less than 90°. This helps to direct the occlusal forces along the long axis of the tooth. - You can test to see if a rest seat is ‘positive’ (less than 90°) by trying to slide an explorer tip off the rest seat. - An angle of more than 90° fails to transmit the occlusal forces along the long axis of the tooth and permits movement of the clasp assembly away from the abutment and orthodontic movement of the tooth. Labelled diagram comparing occlusal rest seat angles. Top right shows a 'Less than 90°' angle with an explorer tip resting securely on the floor of the rest seat. Bottom left shows a 'Positive' Rest Seat (< 90°) where the text notes the 'Explorer will NOT slip off rest seat if pulled proximally'. Bottom right shows a 'Rest Seat not Positive' (>90°) where the text notes the 'Explorer WILL slip off rest seat if pulled proximally'. ## **Lingual rest seat** Can be done by cutting tooth structure or Adding composite Cingulum of anterior teeth especially canine, due to its well-developed cingulum. Convex M/D Concave B-L: V shaped Floor less than 90° Rounded, no sharp line angles Minimum reduction 0.8 mm  #### Preparation Methods and Location - Can be done by cutting tooth structure or adding composite. - Cingulum of anterior teeth especially canine, due to its well-developed cingulum. #### Design Specifications - Convex M/D. - Concave B-L: V shaped. - Floor less than 90°. - Rounded, no sharp line angles. - Minimum reduction 0.8 mm. A composite diagram illustrating the preparation of a lingual rest seat on an anterior tooth (specifically a canine). The image contains four panels: top-left shows a mesial view with a red arc indicating the concave V-shaped floor; bottom-left shows a labial view with a small red line marking the entry point or reduction; right side shows a lateral view with vertical purple lines indicating the convex mesio-distal walls and the depth of the preparation. Labels A, B, and C at the bottom correspond to three white anatomical models showing the prepared cingulum from occlusal (A), labial (B), and lingual (C) perspectives. **Lingual rest seat** **Correct Preparation:** The cingulum rest seat should be prepared in the bulk of the cingulum to minimize tooth reduction. The cavosurface should be less than 90° to prevent orthodontic movements of the tooth. **Less than 90°**  #### Correct Preparation The cingulum rest seat should be prepared in the bulk of the cingulum to minimize tooth reduction. The cavosurface should be less than 90° to prevent orthodontic movements of the tooth. Labeled diagram illustrating the correct preparation of a lingual rest seat on a tooth. The visual consists of three panels: (1) A line drawing of a tooth from the mesial aspect showing the general anatomy; (2) A detailed view of the cingulum area with shaded regions indicating material removal and a dashed line labeled 'Less than 90°' demonstrating the cavosurface angle requirement to prevent orthodontic movements; (3) An occlusal view of the tooth showing the location of the rest seat. ## Figures **Lingual rest seat** **Preparation Too High:** If the preparation is started too high above the cingulum proper, much of the lingual surface of the tooth above the cingulum will need to be reduced, in order to obtain sufficient width for support. On maxillary anteriors, this may also cause the rest to interfere with the opposing tooth.  #### Preparation Too High If the preparation is started too high above the cingulum proper, much of the lingual surface of the tooth above the cingulum will need to be reduced, in order to obtain sufficient width for support. On maxillary anteriors, this may also cause the rest to interfere with the opposing tooth. Labeled diagram illustrating 'Preparation Too High' for a lingual rest seat. The visual consists of two panels: the left panel shows a side view of a tooth with an arrow indicating 'Unnecessary Reduction' on the lingual surface above the cingulum; the right panel provides a cross-sectional or occlusal view showing the resulting wide preparation area in grey. # Lingual rest seat ## Preparation Too Low **_Preparation Too Low_** If the preparation is started too low, much of the cingulum will need to be reduced, in order to obtain sufficient width for support. Enamel is thinner in this area, and preparation could result in dentinal exposure, resulting in sensitivity. If correction of the outline form or depth is required, there will be little tooth structure remaining to make such changes.  #### Preparation Too Low If the preparation is started too low, much of the cingulum will need to be reduced, in order to obtain sufficient width for support. Enamel is thinner in this area, and preparation could result in dentinal exposure, resulting in sensitivity. If correction of the outline form or depth is required, there will be little tooth structure remaining to make such changes. Labelled diagram illustrating a 'Preparation Too Low' error in dental anatomy. The image displays two views of a tooth: a lateral view on the left and an occlusal view on the right. An arrow points to the lingual cingulum area with the label 'Excessive cingulum reduction', indicating where the preparation has been lowered too much. # **Lingual rest seat** Care must be taken not to create an enamel undercut that would interfere with the placement of the denture. A medium or large diameter cylindrical fissure bur should be utilized approaching along the long axis of the tooth. Approach from a horizontal direction will often result in creation of an undercut incisal to the rest seat. **Correct** **Incorrect**  #### Instrumentation and Undercuts Care must be taken not to create an enamel undercut that would interfere with the placement of the denture. A medium or large diameter cylindrical fissure bur should be utilized approaching along the long axis of the tooth. Approach from a horizontal direction will often result in creation of an undercut incisal to the rest seat. - Correct - Incorrect Comparison diagram illustrating the correct and incorrect approach for preparing a lingual rest seat. The left panel, labeled 'Correct', shows a dental bur approaching the tooth along its long axis (vertically). The right panel, labeled 'Incorrect', depicts a horizontal approach that results in an undercut incisal to the rest seat, which would interfere with denture placement. **Lingual rest seat** A **rest** placed on an unprepared cingulum results in force being applied in a labial direction. Orthodontic movement will occur with osteoclastic activity around the centre of rotation of the root. A rest seat prepared in the cingulum of the tooth results in the forces being directed along the long axis of the tooth.  #### Biomechanical Considerations A rest placed on an unprepared cingulum results in force being applied in a labial direction. Orthodontic movement will occur with osteoclastic activity around the centre of rotation of the root. A rest seat prepared in the cingulum of the tooth results in the forces being directed along the long axis of the tooth. Anatomical line diagram of a tooth illustrating the effects of a lingual rest seat. The diagram shows an arrow pointing to the cingulum area representing applied force. It visualizes 'Osteoclastic activity' occurring on both sides of the root and indicates the 'Center of rotation of the tooth' located in the middle of the root, demonstrating how forces are directed along the long axis. **Composite Buildups for Cingulum Rests** When a cingulum is poorly developed, with insufficient bulk for preparation for a cingulum rest seat, a rest seat can be made using composite resin. The cervical portion of the buildup should have a flat emergence profile (not over contoured) with bulk increasing toward the incisal. The bonded rest seat should be smooth and well polished, with no sharp line angles. Correct Overcontoured Overcontoured Open margin  #### Indications and Technique When a cingulum is poorly developed, with insufficient bulk for preparation for a cingulum rest seat, a rest seat can be made using composite resin. #### Contour and Finish - The cervical portion of the buildup should have a flat emergence profile (not over contoured) with bulk increasing toward the incisal. - The bonded rest seat should be smooth and well polished, with no sharp line angles. #### Clinical Outcomes - Correct - Overcontoured - Overcontoured Open margin Labeled comparison figure showing three cross-sectional diagrams of a tooth with composite buildup for a cingulum rest. The left panel labeled 'Correct' shows a proper emergence profile with flat cervical bulk increasing toward the incisal. The middle panel labeled 'Overcontoured' demonstrates excessive bulk at the cervical margin. The right panel labeled 'Overcontoured Open margin' illustrates improper contouring resulting in an open margin. Thank You Sources: - Removable Partial Denture Manual Robert W. Loney, DMD, MS 2011 - McCracken’s REMOVABLE PARTIAL PROSTHODONTICS Thank You #### Primary Sources - Removable Partial Denture Manual, Robert W. Loney, DMD, MS, 2011 - McCracken’s Removable Partial Prosthodontics [^1]: Original PDF page 1: [[L12 Marwa RPD Final CSSL presentation.pdf#page=1|L12 Marwa RPD Final CSSL presentation, p.1]] [^2]: Original PDF page 2: [[L12 Marwa RPD Final CSSL presentation.pdf#page=2|L12 Marwa RPD Final CSSL presentation, p.2]] [^3]: Original PDF page 3: [[L12 Marwa RPD Final CSSL presentation.pdf#page=3|L12 Marwa RPD Final CSSL presentation, p.3]] [^4]: Original PDF page 4: [[L12 Marwa RPD Final CSSL presentation.pdf#page=4|L12 Marwa RPD Final CSSL presentation, p.4]] [^5]: Original PDF page 5: [[L12 Marwa RPD Final CSSL presentation.pdf#page=5|L12 Marwa RPD Final CSSL presentation, p.5]] [^6]: Original PDF page 6: [[L12 Marwa RPD Final CSSL presentation.pdf#page=6|L12 Marwa RPD Final CSSL presentation, p.6]] [^7]: Original PDF page 7: [[L12 Marwa RPD Final CSSL presentation.pdf#page=7|L12 Marwa RPD Final CSSL presentation, p.7]] [^8]: Original PDF page 8: [[L12 Marwa RPD Final CSSL presentation.pdf#page=8|L12 Marwa RPD Final CSSL presentation, p.8]] [^9]: Original PDF page 9: [[L12 Marwa RPD Final CSSL presentation.pdf#page=9|L12 Marwa RPD Final CSSL presentation, p.9]] [^10]: Original PDF page 10: [[L12 Marwa RPD Final CSSL presentation.pdf#page=10|L12 Marwa RPD Final CSSL presentation, p.10]] [^11]: Original PDF page 11: [[L12 Marwa RPD Final CSSL presentation.pdf#page=11|L12 Marwa RPD Final CSSL presentation, p.11]] [^12]: Original PDF page 12: [[L12 Marwa RPD Final CSSL presentation.pdf#page=12|L12 Marwa RPD Final CSSL presentation, p.12]] [^13]: Original PDF page 13: [[L12 Marwa RPD Final CSSL presentation.pdf#page=13|L12 Marwa RPD Final CSSL presentation, p.13]] [^14]: Original PDF page 14: [[L12 Marwa RPD Final CSSL presentation.pdf#page=14|L12 Marwa RPD Final CSSL presentation, p.14]] [^15]: Original PDF page 15: [[L12 Marwa RPD Final CSSL presentation.pdf#page=15|L12 Marwa RPD Final CSSL presentation, p.15]] [^16]: Original PDF page 16: [[L12 Marwa RPD Final CSSL presentation.pdf#page=16|L12 Marwa RPD Final CSSL presentation, p.16]] [^17]: Original PDF page 17: [[L12 Marwa RPD Final CSSL presentation.pdf#page=17|L12 Marwa RPD Final CSSL presentation, p.17]] [^18]: Original PDF page 18: [[L12 Marwa RPD Final CSSL presentation.pdf#page=18|L12 Marwa RPD Final CSSL presentation, p.18]] [^19]: Original PDF page 19: [[L12 Marwa RPD Final CSSL presentation.pdf#page=19|L12 Marwa RPD Final CSSL presentation, p.19]] [^20]: Original PDF page 20: [[L12 Marwa RPD Final CSSL presentation.pdf#page=20|L12 Marwa RPD Final CSSL presentation, p.20]] [^21]: Original PDF page 21: [[L12 Marwa RPD Final CSSL presentation.pdf#page=21|L12 Marwa RPD Final CSSL presentation, p.21]] [^22]: Original PDF page 22: [[L12 Marwa RPD Final CSSL presentation.pdf#page=22|L12 Marwa RPD Final CSSL presentation, p.22]] [^23]: Original PDF page 23: [[L12 Marwa RPD Final CSSL presentation.pdf#page=23|L12 Marwa RPD Final CSSL presentation, p.23]] [^24]: Original PDF page 24: [[L12 Marwa RPD Final CSSL presentation.pdf#page=24|L12 Marwa RPD Final CSSL presentation, p.24]] [^25]: Original PDF page 25: [[L12 Marwa RPD Final CSSL presentation.pdf#page=25|L12 Marwa RPD Final CSSL presentation, p.25]] [^26]: Original PDF page 26: [[L12 Marwa RPD Final CSSL presentation.pdf#page=26|L12 Marwa RPD Final CSSL presentation, p.26]] [^27]: Original PDF page 27: [[L12 Marwa RPD Final CSSL presentation.pdf#page=27|L12 Marwa RPD Final CSSL presentation, p.27]] [^28]: Original PDF page 28: [[L12 Marwa RPD Final CSSL presentation.pdf#page=28|L12 Marwa RPD Final CSSL presentation, p.28]] [^29]: Original PDF page 29: [[L12 Marwa RPD Final CSSL presentation.pdf#page=29|L12 Marwa RPD Final CSSL presentation, p.29]] [^30]: Original PDF page 30: [[L12 Marwa RPD Final CSSL presentation.pdf#page=30|L12 Marwa RPD Final CSSL presentation, p.30]] [^31]: Original PDF page 31: [[L12 Marwa RPD Final CSSL presentation.pdf#page=31|L12 Marwa RPD Final CSSL presentation, p.31]] [^32]: Original PDF page 32: [[L12 Marwa RPD Final CSSL presentation.pdf#page=32|L12 Marwa RPD Final CSSL presentation, p.32]] [^33]: Original PDF page 33: [[L12 Marwa RPD Final CSSL presentation.pdf#page=33|L12 Marwa RPD Final CSSL presentation, p.33]] [^34]: Original PDF page 34: [[L12 Marwa RPD Final CSSL presentation.pdf#page=34|L12 Marwa RPD Final CSSL presentation, p.34]] [^35]: Original PDF page 35: [[L12 Marwa RPD Final CSSL presentation.pdf#page=35|L12 Marwa RPD Final CSSL presentation, p.35]] [^36]: Original PDF page 36: [[L12 Marwa RPD Final CSSL presentation.pdf#page=36|L12 Marwa RPD Final CSSL presentation, p.36]] [^37]: Original PDF page 37: [[L12 Marwa RPD Final CSSL presentation.pdf#page=37|L12 Marwa RPD Final CSSL presentation, p.37]] [^38]: Original PDF page 38: [[L12 Marwa RPD Final CSSL presentation.pdf#page=38|L12 Marwa RPD Final CSSL presentation, p.38]] [^39]: Original PDF page 39: [[L12 Marwa RPD Final CSSL presentation.pdf#page=39|L12 Marwa RPD Final CSSL presentation, p.39]] [^40]: Original PDF page 40: [[L12 Marwa RPD Final CSSL presentation.pdf#page=40|L12 Marwa RPD Final CSSL presentation, p.40]] [^41]: Original PDF page 41: [[L12 Marwa RPD Final CSSL presentation.pdf#page=41|L12 Marwa RPD Final CSSL presentation, p.41]] [^42]: Original PDF page 42: [[L12 Marwa RPD Final CSSL presentation.pdf#page=42|L12 Marwa RPD Final CSSL presentation, p.42]] [^43]: Original PDF page 43: [[L12 Marwa RPD Final CSSL presentation.pdf#page=43|L12 Marwa RPD Final CSSL presentation, p.43]]