THE UNIVERSITY OF WESTERN AUSTRALIA Oral Health Centre of Western Australia # Fixed Dental Prosthesis ## COMPONENTS Acknowledgements to Dr Matsubara   #### Oral Health Centre of Western Australia This section outlines the fundamental components of a fixed dental prosthesis. *Acknowledgements to Dr Matsubara* Clinical photo of a dental bridge model showing the upper anterior teeth with blue and pink stains applied to the occlusal surfaces. This likely demonstrates staining patterns for diagnostic or educational purposes related to Fixed Dental Prosthesis components. Clinical photo of a dental bridge model showing the lower anterior teeth without any visible stains. This appears to be an untreated control or comparison image alongside the stained upper arch. Before we begin Going over DMD2 single unit indirect restoration exam answers • Overall exam was completed well, good understanding of some dental materials • Some incorrect answers regarding the steps of impressions • Answers also need to be clearer 1. Please outline in dot points the clinical steps of EACH pair of two different impression techniques. For each listed PAIR of impression techniques, also state which technique is more accurate? a. PVS Monophase vs PVS Dual phase a. Putty wash 1-step vs Putty wash 2-step Please only write 4-6 dot points per sub-section.  #### Review of DMD2 Single Unit Indirect Restoration Exam - Overall exam was completed well, showing a good understanding of some dental materials. - Some incorrect answers were provided regarding the steps of impressions. - Answers need to be clearer in future assessments. #### Assessment Task Requirements Outline in dot points the clinical steps of each pair of the following impression techniques and state which technique is more accurate (4-6 dot points per sub-section): 1. PVS Monophase vs. PVS Dual phase 2. Putty wash 1-step vs. Putty wash 2-step Text-based procedure outlining the clinical steps for two pairs of impression techniques: 'PVS Monophase vs PVS Dual phase' and 'Putty wash 1-step vs Putty wash 2-step'. Includes instructions to outline steps in dot points and state which technique is more accurate for each pair. Specifies a constraint to write 4-6 dot points per sub-section. # **Before we begin** ## **Monophase** *preparation with retraction cord* *preparation covered with impression material* *tray inserted with the same impression material* NOT RECCOMENDED DUE TO LOWER DEFINITION ## **Dualphase - Lightbody & Heavybody** *preparation with retraction cord* *preparation covered with lightbody (LB) material* *tray inserted with heavy body (HB) material* ## **Two-step impression with Putty** *preparation with retraction cord* *Impression with putty* *Putty cut-out* *Preparation / putty cut-out covered with lightbody (LB)* Good accuracy ## **Dualphase - "Putty Wash"** *preparation with retraction cord* *preparation covered with lightbody (LB) material* *tray inserted with putty material* One-step putty impressions can have significantly lower accuracy compared to two step impressions     #### Monophase Technique - Preparation with retraction cord - Preparation covered with impression material - Tray inserted with the same impression material - **Note:** Not recommended due to lower definition #### Dualphase Technique (Lightbody & Heavybody) - Preparation with retraction cord - Preparation covered with lightbody (LB) material - Tray inserted with heavy body (HB) material #### Two-Step Impression with Putty - Preparation with retraction cord - Impression with putty - Putty cut-out - Preparation / putty cut-out covered with lightbody (LB) - **Note:** Good accuracy #### Dualphase "Putty Wash" (One-Step) - Preparation with retraction cord - Preparation covered with lightbody (LB) material - Tray inserted with putty material - **Note:** One-step putty impressions can have significantly lower accuracy compared to two-step impressions Visual procedure diagram for 'Monophase' impression technique. Contains three sequential panels: (1) preparation with retraction cord, (2) preparation covered with impression material, and (3) tray inserted with the same impression material. Includes caption text 'NOT RECCOMENDED DUE TO LOWER DEFINITION'. Visual procedure diagram for 'Dualphase – Lightbody & Heavybody' impression technique. Contains three sequential panels: (1) preparation with retraction cord, (2) preparation covered with lightbody (LB) material, and (3) tray inserted with heavy body (HB) material. Visual procedure diagram for 'Dualphase – Putty Wash' impression technique. Contains three sequential panels: (1) preparation with retraction cord, (2) preparation covered with lightbody (LB) material, and (3) tray inserted with putty material. Includes caption text regarding accuracy comparison. Visual procedure diagram for 'Two-step impression with Putty'. Shows four steps in a grid layout: (1) preparation with retraction cord, (2) Impression with putty, (3) Putty cut-out, and (4) Preparation / putty cut-out covered with lightbody (LB). Includes caption text 'Good accuracy'. Heading: Before we begin Top right logos: The University of Western Australia | Oral Health Centre of Western Australia 1. Please outline in dot points the clinical steps of EACH pair of two different impression techniques. For each listed PAIR of impression techniques, also state which technique is more accurate? - PVS Monophase vs PVS Dual phase - Putty wash 1-step vs Putty wash 2-step Please only write 4-6 dot points per sub-section. Answer I was looking for: PVS Monophase: **Medium/Heavy body PVS** material in the tray + on the preparation PVS Dualphase: **Heavy/medium body PVS** material in the tray, **Lightbody PVS** material expressed on the tooth Putty wash 1-step: Putty mixed and placed into tray, **light body PVS** expressed onto the prepared tooth and tray immediately inserted. Putty wash 2-step: Putty mixed and placed into tray. Tray inserted into the mouth, impression taken and removed from mouth. Cut out area around prepared tooth. **Light body PVS** applied on prepared tooth, impression taken using putty/tray unit. #### Clinical Steps Comparison **PVS Monophase vs. PVS Dual Phase** - **PVS Monophase:** Medium/Heavy body PVS material in the tray + on the preparation. - **PVS Dualphase:** Heavy/medium body PVS material in the tray, Lightbody PVS material expressed on the tooth. **Putty Wash 1-Step vs. Putty Wash 2-Step** - **Putty wash 1-step:** Putty mixed and placed into tray, light body PVS expressed onto the prepared tooth and tray immediately inserted. - **Putty wash 2-step:** 1. Putty mixed and placed into tray. 2. Tray inserted into the mouth, impression taken and removed. 3. Cut out area around prepared tooth. 4. Light body PVS applied on prepared tooth, impression taken using putty/tray unit. # Before we begin ## Answer I was looking for: **PVS Monophase**: **Medium/Heavy body PVS** material in the **tray** + on the **preparation** **PVS Dualphase**: **Heavy/medium body PVS** material in the **tray**, **Lightbody PVS** material expressed on the **tooth** **Putty wash 1-step**: **Putty mixed** and placed into **tray**, **light body PVS** expressed onto the prepared **tooth** and **tray immediately inserted**. **Putty wash 2-step**: **Putty mixed** and placed into **tray**. **Tray inserted** into the mouth, **impression taken** and removed from mouth. **Cut out area** around prepared **tooth**. **Light body PVS** applied on prepared **tooth**, **impression taken** using putty/tray unit. Not able to award full marks if you: * Did not specify the impression material used. “impression material placed on tooth” (*what* impression materials? *Light body?* *Heavy body?* *Alginate?*) Confusion seems to exist regarding the Putty wash 1-step vs Putty wash 2-step. Some answers said you take impression with the putty, then apply the light body onto the putty. #### Detailed Technique Comparison - **PVS Monophase:** Medium/Heavy body PVS material in the tray + on the preparation. - **PVS Dualphase:** Heavy/medium body PVS material in the tray, Lightbody PVS material expressed on the tooth. - **Putty wash 1-step:** Putty mixed and placed into tray, light body PVS expressed onto the prepared tooth and tray immediately inserted. - **Putty wash 2-step:** Putty mixed and placed into tray. Tray inserted into the mouth, impression taken and removed. Cut out area around prepared tooth. Light body PVS applied on prepared tooth, impression taken using putty/tray unit. #### Common Errors in Assessment - **Lack of Specificity:** Full marks were not awarded if the specific impression material was not identified (e.g., stating "impression material" without specifying Light body, Heavy body, or Alginate). - **Procedural Confusion:** Confusion exists regarding Putty wash 1-step vs. 2-step. Some incorrectly stated taking an impression with putty and then applying light body directly onto the putty. # Module Overview **THE UNIVERSITY OF WESTERN AUSTRALIA** | **Oral Health Centre of Western Australia** * Practical assessment: Bridge preparation + provisional bridge (marking rubric will be released to you later) * Formative assessment: 13/04/26 ***No weighting*** * Summative assessment: 11/05/26 (the timetable columns seem to be jumbled up) ***50% of module*** * Workbook to be completed * Theoretical exam: Held at main campus, main round exam time. ***50% of module*** * MCQs and SAQs * Likely as combined exam with FPD Please note both the summative assessment and theoretical exams need to be passed **(50%+)** to successfully pass the module. The summative assessment is made of TWO components, which must be independently passed **(50%+ must be achieved on both tasks)**. #### Assessment Components - **Practical Assessment: Bridge preparation + provisional bridge** - Formative assessment: 13/04/26 (No weighting) - Summative assessment: 11/05/26 (50% of module) - **Workbook:** To be completed as part of the module. - **Theoretical Exam:** Held at main campus (50% of module) - Format: MCQs and SAQs - Likely combined with FPD exam #### Passing Requirements - Both the summative assessment and theoretical exams must be passed with a score of **50%+**. - The summative assessment consists of two components; both tasks must be independently passed with a minimum score of **50%**. **Learning outcomes** Learning outcomes: * Discuss the components of a fixed partial prosthesis * Discuss the principles of tooth preparation: Biological, Aesthetic and Mechanical * Understand the concept of Path of Insertion * Discuss different designs of retainers * Discuss different designs of pontics * Discuss different types of connectors * Understand the concept of Cantilever **Reading:** Contemporary Fixed Prosthodontics: Chapter 20 Pontic Design  #### Learning Outcomes - Discuss the components of a fixed partial prosthesis. - Discuss the principles of tooth preparation: Biological, Aesthetic, and Mechanical. - Understand the concept of Path of Insertion. - Discuss different designs of retainers. - Discuss different designs of pontics. - Discuss different types of connectors. - Understand the concept of Cantilever. #### Required Reading - *Contemporary Fixed Prosthodontics*: Chapter 20, Pontic Design Institutional logo for The University of Western Australia and the Oral Health Centre of Western Australia. This visual element serves as a branding identifier rather than an educational figure demonstrating or summarizing prosthodontic concepts. Tooth Supported Bridgework (Fixed partial prosthesis) THE UNIVERSITY OF WESTERN AUSTRALIA Oral Health Centre of Western Australia   Tooth Supported Bridgework (Fixed partial prosthesis) Clinical photo showing the pre-operative condition of a patient's upper anterior teeth. There is a visible gap (edentulous space) in the central region, flanked by teeth with significant wear and discoloration. The left canine appears to have a metal restoration or crown. Clinical photo showing the post-operative result following tooth-supported bridgework (fixed partial prosthesis). The edentulous space has been restored with dental prosthetics that match the adjacent natural teeth in color and shape, completing the anterior dentition. Implant Supported Bridgework The University of Western Australia | Oral Health Centre of Western Australia   Implant Supported Bridgework Clinical intraoral photograph showing the anterior view of a patient's mouth with an implant-supported fixed dental prosthesis (bridgework) in place. The upper and lower arches are fully restored with prosthetic teeth. Composite radiographic figure consisting of multiple periapical X-ray panels arranged in two rows. These images demonstrate the osseointegration and positioning of multiple endosseous dental implants supporting bridgework structures in both the maxilla and mandible.   Diagram showing the internal root structure of abutment teeth (labeled 1, 2, and 3) connected by a metal framework. The image includes labels for 'Abutment teeth' pointing to the tooth roots. Diagram illustrating the external components of a dental bridge with arrows pointing to 'Retainers', 'Pontics', and 'Connectors'. The retainer is highlighted in red, while the pontic is shown as a yellowish restoration. <tr><td>Components</td><td>R</td><td>Oral Health Centre</td><td>of Western Australia</td><td>Contemporary Fixed Prosthodontics, 4th ed</td></tr><tr><td colspan="4">The University of Western Australia</td></tr><tr><td colspan="4">Cantilever</td></tr>  #### Structural Overview - Components - Cantilever Anatomical diagram illustrating components of a fixed dental prosthesis. The image displays a cross-section of the jawbone with natural teeth on the left and right sides, an implant fixture in the center, and corresponding tooth-shaped prosthetic crowns below. A red arrow labeled 'Cantilever' points to the anterior-most prosthetic crown (a central incisor), indicating its unsupported extension from the implant-supported structure. The source text identifies this as being from 'Contemporary Fixed Prosthodontics, 4th ed' by The University of Western Australia. **Components** To be successful, single abutment cantilevers require a very favorable occlusion. **FIGURE 3-16** ■ **A**, Forces applied to a cantilever fixed dental prosthesis are resisted on only one side, which leads to imbalance. Vertical forces can cause tipping, and horizontal forces can cause rotation, of abutment teeth. **B**, By including both adjacent teeth in the prosthesis, it is possible to resist forces much better because the teeth have to be moved bodily rather than merely rotated or tipped. (Redrawn from Rosenstiel SF: Fixed bridework—the basic principles. In Rayne J, ed: General Dental Treatment. London, Kluwer Publishing, 1983.)  #### Cantilever Mechanics To be successful, single abutment cantilevers require a very favorable occlusion. - **Force Resistance**: Forces applied to a cantilever fixed dental prosthesis are resisted on only one side, which leads to imbalance. Vertical forces can cause tipping, and horizontal forces can cause rotation of abutment teeth. - **Multi-Abutment Support**: By including both adjacent teeth in the prosthesis, it is possible to resist forces much better because the teeth have to be moved bodily rather than merely rotated or tipped. Labelled diagram: Figure 3-16 illustrating forces on fixed dental prostheses. Panel A shows a cantilever prosthesis with vertical and horizontal force arrows causing tipping and rotation of the abutment teeth, labeled accordingly. Panel B shows a prosthesis spanning two adjacent teeth with downward force arrows indicating bodily movement rather than tipping or rotation. The caption explains that single abutment cantilevers require favorable occlusion to resist imbalance, while including both adjacent teeth allows better resistance by moving teeth bodily. **Indications** **The University of Western Australia** **Oral Health Centre of Western Australia** When would we consider restoring teeth via FPDs? * Patient unable/unwilling to accept removable options. * Orthodontic reasons (replacement of missing lateral incisors) * When adjacent teeth would also benefit from indirect restorations * Patient not suited for implants (eg. Bone) * Splinting teeth (**Mentioned in textbooks, but I would suggested to proceed with care**)   Restoring teeth via Fixed Partial Dentures (FPDs) is considered in the following scenarios: - Patient unable or unwilling to accept removable options. - Orthodontic reasons (e.g., replacement of missing lateral incisors). - When adjacent teeth would also benefit from indirect restorations. - Patient not suited for implants (e.g., insufficient bone). - Splinting teeth (Note: Proceed with care despite mention in textbooks). Panoramic dental radiograph (OPG) of the mandible showing a full lower arch. The image demonstrates multiple missing teeth and several fixed partial dentures (bridges). Specifically, there is a bridge replacing posterior teeth on the left side and another bridge spanning the anterior region. This visual serves as an example for indications where FPDs are used, such as when adjacent teeth benefit from indirect restorations or when splinting teeth. Intraoral periapical radiograph showing the right posterior maxilla. The image features a large fixed partial denture replacing a missing molar. Below the prosthesis, there is a significant area of radiolucency indicating alveolar bone loss. The caption below explicitly labels this as 'Insufficient bone height/dimensions for implant', illustrating a scenario where implants are not viable and FPDs may be indicated. # Contra-indications ## The University of Western Australia Oral Health Centre of Western Australia What do we have to be wary of? * **Poor periodontal status of abutments** (Crown root ratio, Ante’s law etc). * Absence of distal abutment in posterior sections * Long span bridges * **Poor OH** * Extremely tilted teeth (not firm contra-indication, but needs to be carefully assessed) Factors requiring careful assessment or caution include: - **Poor periodontal status of abutments**: Considerations include crown-root ratio and Ante’s law. - **Absence of distal abutment**: Specifically in posterior sections. - **Long span bridges**. - **Poor Oral Hygiene (OH)**. - **Extremely tilted teeth**: Requires careful assessment rather than being a firm contra-indication. # Recap: Components **THE UNIVERSITY OF WESTERN AUSTRALIA | Oral Health Centre of Western Australia** ## ABUTMENT TOOTH * Principles of tooth preparation * Partial or complete preparation ## BIOLOGICAL * Conservation of tooth structure * Avoidance of overcontouring * Supragingival margins * Harmonious occlusion * Protection against tooth fracture ## MECHANICAL * Retention form * Resistance form * Deformation ## AESTHETIC * Minimum display of metal * Maximum thickness of porcelain * Porcelain occlusal surfaces * Subgingival margins  #### Abutment Tooth Considerations - Principles of tooth preparation - Partial or complete preparation #### Biological Principles - Conservation of tooth structure - Avoidance of overcontouring - Supragingival margins - Harmonious occlusion - Protection against tooth fracture #### Mechanical Principles - Retention form - Resistance form - Deformation #### Aesthetic Principles - Minimum display of metal - Maximum thickness of porcelain - Porcelain occlusal surfaces - Subgingival margins Venn diagram illustrating the three components of abutment tooth preparation: Biological (yellow circle), Mechanical (green circle), and Aesthetic (blue circle). The circles overlap to show relationships between the categories. Each circle contains bullet points detailing specific aspects such as 'Conservation of tooth structure' for Biological, 'Retention form' for Mechanical, and 'Minimum display of metal' for Aesthetic. Components  Components Clinical photo showing a dental model with three teeth and blue lines indicating components or alignment guides. The image is labeled 'Components' at the top.  Clinical photograph of a dental model showing three teeth embedded in pink gingival tissue. The central tooth is a molar with a broad occlusal surface and rounded buccal contours; the left tooth is an incisor with a pointed incisal edge; the right tooth appears to be a premolar or canine with visible cusp morphology. A vertical blue line annotation is drawn along the mesial aspect of the leftmost incisor, likely indicating a reference plane or anatomical boundary for educational purposes. Components THE UNIVERSITY OF WESTERN AUSTRALIA | Oral Health Centre of Western Australia  Components Clinical or anatomical model photo showing three teeth with a blue vertical line indicating the midline of the central tooth. The image demonstrates components related to dental anatomy or prosthetics. **Components**  Components Clinical photograph or model of anterior teeth (incisors) demonstrating components. The image shows three artificial teeth in a pink gum base against a black background. A blue vertical line is drawn on the rightmost tooth, likely indicating a specific anatomical feature or measurement point relevant to the 'Components' title. **Components** The University of Western Australia Oral Health Centre of Western Australia  Components Clinical figure showing a dental cast with three visible teeth: an incisor on the left and two premolars/molars on the right. The image demonstrates anatomical components of dentition against a black background. # Components **The University of Western Australia** | **Oral Health Centre of Western Australia**  Components Clinical photograph of a dental model showing three anterior teeth (likely incisors) embedded in pink gingival tissue. Blue vertical lines are overlaid on the image, likely indicating anatomical landmarks or axes for study purposes. Components THE UNIVERSITY OF Western Australia Oral Health Centre of Western Australia  Components Clinical photograph showing a dental model with upper and lower arches. The upper section displays individual teeth mounted in pink gum tissue, while the lower section shows a metallic fixed partial denture (bridge) spanning multiple units. This visual demonstrates components of a prosthodontic restoration. Components **THE UNIVERSITY OF WESTERN AUSTRALIA** Oral Health Centre of Western Australia  Components Clinical photo of a metal-ceramic dental bridge or partial denture framework seated on a pink acrylic gum model. The image shows metallic crowns and connectors with anatomical tooth shapes, demonstrating the physical components of a prosthesis. **Components** The University of Western Australia | Oral Health Centre of Western Australia  Components Clinical photograph of a dental model showing the anterior maxillary arch with five teeth. The image is titled 'Components' and includes branding for The University of Western Australia and Oral Health Centre of Western Australia. # Components  Clinical diagram illustrating dental components. The image shows a close-up of three teeth (likely anterior dentition) with blue vertical lines indicating alignment or anatomical reference points. One tooth on the left is highlighted in brown and outlined, possibly to denote a specific component such as an implant abutment, crown margin, or restoration interface. The title 'Components' suggests this visual demonstrates parts of a dental prosthesis or implant system. **Components** THE UNIVERSITY OF WESTERN AUSTRALIA Oral Health Centre of Western Australia  Components Clinical diagram illustrating dental components under the title 'Components'. The image shows a close-up view of teeth with a highlighted section on the left side, outlined in black and shaded brown, likely indicating a specific anatomical feature or area of interest. The background includes branding for 'THE UNIVERSITY OF WESTERN AUSTRALIA' and 'Oral Health Centre of Western Australia', suggesting an educational context related to dentistry. # Components  Clinical photograph of three anterior teeth demonstrating the 'Components' of a dental restoration. The leftmost tooth shows a dark brown composite filling (labeled as an overlay) extending into the interproximal area, while the central and right teeth show intact restorations. Three vertical blue lines are superimposed on the image to indicate the midlines or borders of each component. Components **ABUTMENT TOOTH** The University of Western Australia | Oral Health Centre of Western Australia Contemporary Fixed Prosthodontics, 4th ed  Components Labeled diagram illustrating the 'ABUTMENT TOOTH' in a fixed prosthodontic context. The image shows two natural teeth on either side of a missing tooth space, each marked with a yellow downward arrow pointing to their prepared cervical areas for abutment use. Above the gap is a three-unit dental bridge (yellowish crown structure) spanning the edentulous span. On the right abutment tooth, a red starburst symbol highlights an area of caries or decay at the distal aspect near the gingiva. A small purple cross-hatched region indicates possible periodontal involvement or preparation margin detail. This visual demonstrates how adjacent natural teeth serve as supports (abutments) for a fixed partial denture. Components **THE UNIVERSITY of WESTERN AUSTRALIA** Oral Health Centre of Western Australia ABUTMENT TOOTH Contemporary Fixed Prosthodontics, 4th ed  Components Anatomical diagram illustrating dental components for a fixed prosthesis. It shows three artificial crown units (pontics) suspended above a gap in the jaw. Yellow arrows point to two natural teeth on either side of the gap, which are labeled as 'ABUTMENT TOOTH'. These abutment teeth have been prepared with reduced crowns to support the bridge structure. **Components** **ABUTMENT TOOTH** Continuity Fixed Prosthodontics, 14th The University of Western Australia  Components Labeled diagram illustrating the 'ABUTMENT TOOTH' component in a fixed partial denture. The image shows two natural teeth with prepared crowns (indicated by yellow arrows pointing downward) supporting a three-unit bridge prosthesis above them. Labels and context from OCR confirm this is part of a study on 'Components' in Contemporary Fixed Prosthodontics. **Components** ABUTMENT TOOTH **THE UNIVERSITY OF** **WESTERN** **AUSTRALIA** Oral Health Centre of Western Australia Contemporary Fixed Prosthodontics, 4th ed  Components Labeled anatomical diagram illustrating 'ABUTMENT TOOTH' components in fixed prosthodontics. The image shows four teeth: three adjacent anterior/posterior teeth on the left connected by a rigid metal framework (bridge abutments), and one molar tooth on the right separated from them by an edentulous span (gap). A coiled spring connector spans the gap between the last abutment and the final tooth, demonstrating the mechanical linkage or movement involved in the prosthetic assembly. # Components ## RETAINERS Full coverage restoration: All metal, PFM, All ceramic crowns Partial coverage restoration: 4/5, 7/8 Give stability and retention to the dental bridge  Retainers provide stability and retention to the dental bridge. #### Full Coverage Restorations - All metal crowns - PFM (Porcelain-Fused-to-Metal) crowns - All ceramic crowns #### Partial Coverage Restorations - 4/5 crowns - 7/8 crowns Diagram illustrating dental bridge components. Top section shows a partial coverage restoration with crowns on teeth 4 and 5 (or 7 and 8), demonstrating 'Partial coverage restoration'. Bottom section shows a full coverage restoration with crowns on multiple teeth, demonstrating 'Full coverage restoration'. Both diagrams visually represent the concept of retainers giving stability and retention to the dental bridge. **Components** Image of a dental prosthesis with pontics **Glossary of Prosthodontic terms** The university of western australia | Oral Health Centre of western australia **PONTICS** * **Artificial tooth that replaces a missing natural tooth** * **Suspended: tooth supported** * **Restore aesthetic and function** * **Prevent tilting and drifting of adjacent teeth and super-eruption of opposing teeth**  #### Definition and Function According to the Glossary of Prosthodontic terms, a pontic is an artificial tooth that replaces a missing natural tooth. - **Support**: Suspended and tooth-supported. - **Purpose**: - Restore aesthetics and function. - Prevent tilting and drifting of adjacent teeth. - Prevent super-eruption of opposing teeth. Clinical photograph of a dental prosthesis containing pontics. The image shows an artificial tooth replacement with a central natural-looking ceramic crown flanked by two metallic retainer clasps on either side, designed to replace missing teeth and restore function. **Components** <div align='right'> **THE UNIVERSITY OF WESTERN AUSTRALIA** | **Oral Health Centre of Western Australia** </div> **PONTICS** *Design parameters of pontics involve:* * Height and width of the residual ridge   Design parameters of pontics involve: - Height and width of the residual ridge Clinical photo showing the residual ridge and adjacent teeth in an oral cavity. The image demonstrates a dental preparation or bridge abutment area with visible metal crowns on neighboring teeth. Clinical photo of another section of the oral cavity, highlighting the residual ridge between prepared teeth. A metal crown is visible on one tooth, and brackets are present on an adjacent tooth, indicating orthodontic treatment. # PONTICS ## Design parameters of pontics involve: * Height and width of the residual ridge * Dimensions of the edentulous space   Design parameters of pontics involve: - Height and width of the residual ridge - Dimensions of the edentulous space Clinical photo of the lower anterior dentition showing a large edentulous space between the left central incisor and right canine. The adjacent teeth appear to be natural or restored with crowns. This image demonstrates the dimensions of the edentulous space mentioned in the text. Clinical photo of the upper anterior dentition showing an edentulous space between the lateral incisor and canine. The residual ridge is visible within the gap. This image illustrates the height and width of the residual ridge relevant to pontic design parameters. **Components** **THE UNIVERSITY OF WESTERN AUSTRALIA** | **Oral Health Centre of Western Australia** **PONTICS** Design parameters of pontics involve: - Height and width of the residual ridge - Dimensions of the edentate space - Shape and texture of the soft tissues - Comfort and support the adjacent tissues - Aesthetic requirements   Design parameters of pontics involve: - Height and width of the residual ridge - Dimensions of the edentate space - Shape and texture of the soft tissues - Comfort and support of the adjacent tissues - Aesthetic requirements Clinical photo of the upper anterior dentition showing a significant edentulous space in the central incisor region. The adjacent teeth (lateral incisors and canines) are visible with some discoloration on the right lateral incisor. This image demonstrates the 'Dimensions of the edentate space' and 'Shape and texture of the soft tissues' mentioned in the text. Clinical photo of the upper anterior dentition following the placement of pontics. The gap seen in the previous image is now filled with prosthetic teeth, demonstrating the 'Aesthetic requirements' and final restoration design parameters. # Components # **PONTICS** Design parameters of pontics involve: * Height and width of the residual ridge * Dimensions of the edentate space * Shape and texture of the soft tissues * Comfort and support the adjacent tissues * Aesthetic requirements * Access for oral hygiene   Design parameters of pontics involve: - Height and width of the residual ridge - Dimensions of the edentate space - Shape and texture of the soft tissues - Comfort and support of the adjacent tissues - Aesthetic requirements - Access for oral hygiene Clinical photo showing a close-up of anterior teeth with a pontic (false tooth) in the edentate space. A dental floss is being used to demonstrate access for oral hygiene between the pontic and adjacent natural teeth, illustrating the 'Access for oral hygiene' design parameter. Clinical photo demonstrating oral hygiene maintenance around a pontic. An interdental brush is shown inserted into the edentate space between the pontic and adjacent teeth, visually representing the requirement for 'Access for oral hygiene' as listed in the text. Components The University of WA The University of Western Australia OHCWA MECHANICAL Rigid (to resist deformation) Strong connectors (to prevent fracture) Metal-ceramic framework (to resist porcelain fracture) Biologic Cleansable tissue surface Access to abutment teeth No pressure on ridge ESTHETIC Shaped to look like tooth it replaces Appears to "grow" out of edentulous ridge Sufficient space for porcelain Bior 2-2 Biologic, mechanical, and esthetic considerations for successful pontic design Optimal pontic design OPTIMAL PONTIC DESIGN BOX 20-1 Pontic Design Classification MUCOSAL CONTACT Ridge-lap Modified ridge-lap Ovate Conical NO MUCOSAL CONTACT Sanitary (hygienic) Modified sanitary (hygienic) Contemporary Fixed Prosthodontics   #### Mechanical Considerations - Rigid design to resist deformation - Strong connectors to prevent fracture - Metal-ceramic framework to resist porcelain fracture #### Biological Considerations - Cleansable tissue surface - Access to abutment teeth - No pressure on the ridge #### Aesthetic Considerations - Shaped to look like the tooth it replaces - Appears to "grow" out of the edentulous ridge - Sufficient space for porcelain #### Pontic Design Classification - **Mucosal Contact**: - Ridge-lap - Modified ridge-lap - Ovate - Conical - **No Mucosal Contact**: - Sanitary (hygienic) - Modified sanitary (hygienic) Venn diagram illustrating the intersection of three concepts for successful pontic design: Biologic (Cleansable tissue surface, Access to abutment teeth, No pressure on ridge), Mechanical (Rigid, Strong connectors, Metal-ceramic framework), and Esthetic (Shaped to look like tooth it replaces, Appears to 'grow' out of edentulous ridge, Sufficient space for porcelain). The central overlapping area is highlighted in red as the 'Optimal pontic design'. Caption reads: FIGURE 20-2 Biologic, mechanical, and esthetic considerations for successful pontic design. Classification table titled 'BOX 20-1 Pontic Design Classification'. It categorizes designs into two main groups based on mucosal contact. Under 'MUCOSAL CONTACT', it lists Ridge-lap, Modified ridge-lap, Ovate, and Conical. Under 'NO MUCOSAL CONTACT', it lists Sanitary (hygienic) and Modified sanitary (hygienic). **Components** **PONTICS** **Classification:** 1) **SADDLE / RIDGE LAP** * Concave tissue surface * Overlap the residual ridge bucco-lingually * Contraindicated under all circumstances **THE UNIVERSITY OF WESTERN AUSTRALIA** **Oral Health Centre of Western Australia** Figure 20-14 A, Cross-sectional view of ridge-lap pontic. B, The tissue surface is inaccessible to cleaning devices.   #### 1. Saddle / Ridge Lap - **Characteristics**: Concave tissue surface; overlaps the residual ridge bucco-lingually. - **Contraindication**: Contraindicated under all circumstances because the tissue surface is inaccessible to cleaning devices. Clinical photographs of a saddle/ridge lap pontic. The top-left image shows the occlusal view with a concave tissue surface designed to overlap the residual ridge bucco-lingually. The top-right image displays the cross-section of the pontic base revealing the metal framework and the concave shape against the pink acrylic material. Labeled diagram (Figure 20-14) illustrating the ridge-lap pontic design. Panel A shows a cross-sectional view where the pontic overlaps the tooth root. Panel B demonstrates how the pontic sits on the ridge, highlighting that the tissue surface is inaccessible to cleaning devices. **Components** **PONTICS** Classification: 2) **MODIFIED RIDGE LAP** • Lingual modification to open cervical embrasures and facilitate the hygiene • Gentle concavity linguo-facially but is always convex mesio-distally. • Ideally suitable for "convex" gingiva profile with no concavities • High aesthetic A B     #### 2. Modified Ridge Lap - **Characteristics**: - Lingual modification to open cervical embrasures and facilitate hygiene. - Gentle concavity linguo-facially but always convex mesio-distally. - **Indications**: Ideally suitable for "convex" gingiva profiles with no concavities. - **Aesthetics**: High aesthetic value. Line drawing diagram showing two pontic profiles labeled 'A' and 'B'. The diagrams depict the outline of a tooth crown with the gingival margin shown as a wavy line above. These illustrate different contour shapes for the pontic relative to the ridge. Schematic illustration demonstrating the Modified Ridge Lap pontic design. The left sub-figure shows a cross-section of a pontic (white) against pink tissue, highlighting the concave lingual surface and convex facial surface. The right sub-figure shows a top-down view of three teeth in a row, illustrating how the pontic fits between abutment teeth to maintain cervical embrasures. Clinical photograph of a dental bridge pontic viewed from an occlusal angle. It shows the facial porcelain veneer and the underlying metal framework on the lingual side, demonstrating the high aesthetic quality mentioned in the text. Intraoral clinical photograph showing a completed dental bridge in situ. A dental floss is being passed through the contact point between the pontic and adjacent teeth, demonstrating the open cervical embrasure which facilitates hygiene. ``` # Components ## PONTICS Classification: 3) CONICAL * Bullet-shape, egg-shape * Convex with only one point of contact with residual ridge * Posterior region * Not as suitable for broad residual ridges due to food trapping Contemporary Fixed Prosthodontics, 4th ed | The University of Western Australia | Oral Health Centre of Western Australia ```    #### 3. Conical - **Characteristics**: Bullet-shaped or egg-shaped; convex with only one point of contact with the residual ridge. - **Indications**: Posterior region. - **Limitations**: Not as suitable for broad residual ridges due to potential food trapping. Lateral view diagram of a dental bridge showing pontics between abutment teeth. The pink area represents the residual ridge with the gingival contour shown in magenta. Illustrates the conical pontic shape fitting into the space. Cross-sectional diagram comparing original tooth profile (solid line) with resorbed ridge profile (dashed line). Shows how a conical pontic fits into the concave resorbed ridge. Labels include 'Original tooth' and 'Resorbed ridge'. Clinical photograph of an intraoral view showing posterior teeth with missing teeth replaced by fixed prosthesis. Demonstrates placement of pontics in edentulous spaces with visible gingival tissue and adjacent natural/damaged teeth. **Components** PONTICS Classification: 4) Ovate / Spheroidal • Best aesthetic, appears to be emerging from the ridge • Relative ease of hygiene (large tissue contact area) • Convex tissue surface buccal-lingual and mesio- distal directions • May need surgical augmentation (Costly) • Strong pontic design (supported ceramic) FIGURE 20-22 The ovate pontic design eliminates the potential for unsupported porcelain in the cervical portion of an anterior pontic.     #### 4. Ovate / Spheroidal - **Characteristics**: - Convex tissue surface in both buccal-lingual and mesio-distal directions. - Strong design with supported ceramic. - **Advantages**: Best aesthetics (appears to emerge from the ridge); relative ease of hygiene despite large tissue contact area. - **Disadvantages**: May need costly surgical augmentation. Diagram labeled 'FIGURE 20-22' showing two cross-sectional views of pontic designs: 'Ovate' (left) and 'Modified ridge lap' (right). Caption states the ovate design eliminates unsupported porcelain in the cervical portion of an anterior pontic. Clinical photo of a patient's upper anterior teeth showing an ovate pontic with gingival tissue emerging from between the artificial tooth and adjacent natural teeth. Clinical photo of a full set of upper anterior teeth showing multiple ovate pontics integrated into the dental arch with healthy-looking gingival emergence profiles. Photo of a dental model showing a three-unit bridge with ovate pontics, demonstrating the convex tissue surface contact area on both buccal and lingual aspects. **Components** **PONTICS** Classification: 5) Sanitary / Hygienic * **2-3 mm clearance off the ridge** * **Easy cleaning** * **Posterior regions** * Disadvantages: poor aesthetic, entrapment of food, sharp line angle THE UNIVERSITY OF WESTERN AUSTRALIA | Oral Health Centre of Western Australia   #### 5. Sanitary / Hygienic - **Characteristics**: 2-3 mm clearance off the ridge. - **Indications**: Posterior regions where cleaning ease is prioritized. - **Disadvantages**: Poor aesthetics, entrapment of food, and sharp line angles. Lateral cross-section diagram of pontics showing a row of yellow teeth with pink gingival tissue. The pontic is depicted as a white gap between two adjacent teeth, illustrating the space required for hygiene. Interproximal view diagram of a single tooth structure in light pink/grey. A red curved line highlights the contour of the gingiva and the clearance under the pontic, demonstrating the specific anatomical relationship for posterior regions. Components PONTICS Aesthetic considerations - Modified Ridge Lap and Ovate pontics B CORRECT INCORRECT Rounded facial line angle creates a shadow effect     #### Pontic Selection - Modified Ridge Lap and Ovate pontics are preferred for aesthetic regions. #### Visual Effects - A rounded facial line angle creates a shadow effect, which is a key consideration in correct vs. incorrect contouring. Diagram showing a cross-section of a tooth with pontic. Includes labels for anatomical structures (pink gingiva, yellow dentin, red pulp), a green outline indicating the modified ridge lap contour, and a dimension 'H' measuring the height of the pontic above the ridge. Close-up clinical photo of a pontic in situ. Shows the glossy surface of the prosthetic tooth against dark background, demonstrating the contouring of the material. Clinical intraoral photograph labeled 'A'. Shows a patient's lower anterior teeth with multiple pontics replacing missing teeth. The gingival tissue appears healthy around the pontics, demonstrating the aesthetic outcome of the procedure. Comparison diagram illustrating shadow effects created by facial line angles. Left panel labeled 'CORRECT' shows a rounded facial line angle creating a subtle shadow that mimics natural anatomy. Right panel labeled 'INCORRECT' shows a flat or sharp edge creating an unnatural, harsh shadow effect. Caption: 'Rounded facial line angle creates a shadow effect.' # Components ## PONTICS ### Aesthetic considerations - Modified Ridge Lap and Ovate pontics ### Soft tissue management     #### Pontic Selection - Modified Ridge Lap and Ovate pontics #### Soft Tissue Management Clinical photo showing the preparation of a tooth for a dental bridge. A dental handpiece with a bur is actively cutting the enamel of the central incisor, which has been isolated from adjacent teeth. Clinical photo demonstrating 'Modified Ridge Lap' pontics. The image shows two prepared abutment teeth flanking an edentulous space where the gingival margin of the restoration overlaps slightly onto the natural gum tissue (ridge), creating a scalloped appearance. Clinical photo demonstrating 'Ovate' pontics. The image shows a wider edentulous span with a pink acrylic base shaped to mimic the contour of the alveolar ridge and gingiva, sitting between two prepared abutment teeth. Close-up view of a dental bridge component (pontic) against a black background, illustrating the anatomical shape of the restoration designed to fit into the soft tissue. Components Image A: Oral cavity with missing central incisors and surrounding teeth. Image B: Close-up of a dental molar with a crown. Image C: Fabrication of a dental bridge, showing the pontic and abutment teeth. Image D: Final placement and occlusion of the dental bridge in the mouth.  #### Clinical Workflow - Assessment of missing central incisors and surrounding teeth. - Evaluation of abutment crowns. - Fabrication of the dental bridge (pontic and abutment integration). - Final placement and occlusal adjustment. Clinical procedure image showing four stages of dental bridge fabrication and placement. Panel A: Clinical photo of oral cavity with missing central incisors. Panel B: Close-up photo of a dental molar crown. Panel C: Photo of fabricated dental bridge showing pontic and abutment teeth. Panel D: Final clinical photo of the placed dental bridge in occlusion. # Components  Clinical comparison photo showing two states of the anterior dentition. Left panel (labeled 'E') displays a mouth with severe periodontal disease, tooth loss, and remaining teeth exhibiting significant decay and staining. Right panel (labeled 'F') shows a restored smile with full, healthy-looking anterior teeth. Components **Components** **THE UNIVERSITY OF WESTERN AUSTRALIA** Oral Health Centre of Western Australia **PONTICS** **Aesthetic considerations** * Soft tissue ridge augmentation    #### Soft Tissue Ridge Augmentation Considerations for enhancing the aesthetic outcome through surgical ridge modification. Clinical intraoral photograph showing a soft tissue defect adjacent to a molar with a dark metal crown. The gingival margin is receded and bleeding is visible, demonstrating the need for soft tissue ridge augmentation prior to pontic placement. Intraoral clinical photograph depicting a surgical site with sutures in place. This image illustrates the immediate post-operative state of soft tissue ridge augmentation or flap closure between two teeth. Intraoral clinical photograph showing the healed soft tissue ridge between two abutment teeth. The gum contour appears smooth and esthetic, representing the result of successful soft tissue ridge augmentation for a pontic space. # **Components** # PONTICS Aesthetic considerations # **Root surface simulation** # **Soft tissue simulation**   #### Simulation Techniques - Root surface simulation - Soft tissue simulation Clinical photo showing a dental bridge with pontics. Caption reads 'Root surface simulation', illustrating how the crown material mimics the color and texture of the natural tooth root visible below the gum line. Close-up clinical photo of a dental bridge against a dark background. Caption reads 'Soft tissue simulation', demonstrating how the pontic shape is contoured to mimic the appearance of healthy gum tissue between teeth. ### Components - **PONTICS** - Correct configuration of the metallic or ceramic substructure in the pontic area - **Prof Hotinski** - **Image 1:** - **Image 2:** - **Image 3:** - **Image 4:**     #### Substructure Design - Correct configuration of the metallic or ceramic substructure in the pontic area is essential for success. Diagram showing two cross-sectional views of a dental bridge pontic design. The top view includes a central 'open' configuration with an open space for hygiene access, while the bottom shows a solid or closed design. These illustrate correct substructure configurations in the pontic area. Clinical photograph showing a green-stained wax-up or provisional restoration on a dental model. It demonstrates the contour and configuration of the metallic or ceramic substructure in the pontic area. Intraoral clinical photo labeled 'Prof Hotinski', showing a completed dental bridge with a pontic. The image illustrates proper emergence profile and contact points between the pontic and adjacent teeth. Another intraoral clinical photo showing a different angle or stage of a fixed dental prosthesis. Highlights the metallic framework (possibly gold alloy) under porcelain veneering material, demonstrating correct substructure configuration in the pontic region. INTERNAL TEXT EXPLICITLY ON THE IMAGE: **CONNECTORS**   CONNECTORS Clinical photograph showing two dental bridge components: a metal retainer and pontic assembly on the left (partially shown) and a complete three-unit bridge with porcelain-fused-to-metal crowns on the right, demonstrating individual retainers joined to pontics. Clinical photograph of a metal framework for a fixed dental prosthesis embedded in grey dental stone. Yellow arrows point to specific connector regions between the metal segments, illustrating rigid cast connectors joining individual retainers and pontics as described in the text. **Components** **The University of Western Australia** | **Oral Health Centre of Western Australia** **CONNECTORS**    Components Clinical photo showing a patient's upper anterior teeth with a missing central incisor and a visible carious lesion on the adjacent tooth. The gingiva appears inflamed. Photo of a dental cast model demonstrating a metal connector between two crowns or partial denture components. The connector spans the edentulous space. Clinical photo showing a patient's upper anterior teeth with a metal framework connector replacing multiple missing teeth. The connector connects the remaining natural teeth. **Components** CONNECTORS    Components Clinical photo of a dental bridge with metal pontic and abutments in place; red wax or temporary material is visible between the central teeth, demonstrating the connector area under the gum line. Clinical photo showing a dental bridge with red wax used to demonstrate the connector design—specifically highlighting the mesial and distal connectors at the base of the abutment teeth where they meet the pontic. Clinical photo of a cast model of a dental bridge held by gloved fingers, viewed from an occlusal/lingual perspective, clearly displaying the metal framework and connector regions between the artificial teeth. Components **CONNECTORS** Law of beams:  #### Law of Beams Labelled diagram illustrating the 'Law of beams' under a 'CONNECTORS' section. The image displays four distinct beam configurations arranged horizontally. Each configuration shows a yellow rectangular block subjected to a downward force labeled 'F'. From left to right: 1) A single beam with dimensions 3U (height) x 1U (width), supported by an upward reaction force R; 2) Two parallel beams side-by-side with total height 3U and width 2U, supported by two upward forces totaling 2R; 3) A shorter single beam with height 1U and width 1U, supported by force R; 4) Two stacked beams with total height 2U and width 1U, supported by a large upward force labeled 8R. ### Components **The University of Western Australia | Oral Health Centre of Western Australia** #### Figure: Deflection illustration of a fixed dental prosthesis (FDP). **8 times more deflection** Deflection of a fixed dental prosthesis (FDP) is directly proportional to the cube of the length of its span. An FDP with 2 pontics will deflect 2 [3] i.e. 8 times as much as an FDP with 1 pontic. Aslam A, Khan DA, Hassan SH, Ahmed B. Ceramic fracture in metal-ceramic restorations: the aetiology. Dental update. 2017 May 2;44(5):448-56.  #### Deflection Principles Deflection of a fixed dental prosthesis (FDP) is directly proportional to the cube of the length of its span. - **Single Pontic**: Baseline deflection. - **Two Pontics**: An FDP with 2 pontics will deflect 2³ (i.e., 8 times) as much as an FDP with 1 pontic. Line drawing diagram of a dental arch showing fixed dental prosthesis (FDP) deflection. A red arrow points downward onto the central pontic area with a vertical red line indicating the point of force application. The text '8 times more deflection' is placed below the diagram. The visual demonstrates that an FDP with 2 pontics deflects significantly more than one with 1 pontic. **Components** **CONNECTORS** **The University of Western Australia** **Oral Health Centre of Western Australia** Components <font color="#3B53A3">Components</font> THE UNIVERSITY OF WESTERN AUSTRALIA Oral Health Centre of Western Australia CONNECTORS   Components Clinical photograph showing the occlusal view of a dental bridge framework. The image displays two metal connector components: a central lingual connector (trough) connecting to an anterior connector, and another trough-like structure on the right side. The connectors are cast in metal with visible margins against pink wax or gingival material, demonstrating the internal anatomy of fixed partial denture connectors. Clinical photograph of a finished maxillary dental bridge viewed from the labial aspect. The prosthesis consists of multiple teeth connected by dark-colored metal frameworks at the cervical margins and inter-dental areas. This visual demonstrates how connectors are integrated into the final restoration for structural support. # Components ## CONNECTORS Areas of overcontouring   #### Areas of Overcontouring Labeled diagram of anterior teeth showing areas of overcontouring in the gingival embrasures (interproximal spaces). The golden-yellow regions highlight where a connector may be too bulky or convex, impinging on adjacent tissue. Labeled diagram of posterior teeth illustrating areas of overcontouring at the interproximal contact points. These are shown as golden-yellow zones where the connector material extends excessively into the embrasure space. **The University of Western Australia** **Oral Health Centre** **of Western Australia** # Components ## CONNECTORS ### NON-RIGID CONNECTORS * Impossibility to prepare two abutments for a partial FDP with a common path of placement * Segment a large FPD into shorter components that are easier to replace or repair individually Male Female   #### Indications for Non-Rigid Connectors - **Path of Placement**: Used when it is impossible to prepare two abutments for a partial FDP with a common path of placement. - **Segmentation**: Allows segmenting a large FPD into shorter components that are easier to replace or repair individually. #### Components - Male - Female Diagram illustrating the use of non-rigid connectors in a partial Fixed Partial Denture (FDP). It shows two abutment teeth with prepared crowns and three pontics bridging the gap. The connector between the segments is depicted as a non-rigid joint, addressing the impossibility of preparing two abutments for a common path of placement. Diagram showing a large Fixed Partial Denture (FPD) segmented into shorter components using male-female non-rigid connectors. Labels 'Male' and 'Female' indicate the interlocking parts that allow individual replacement or repair. A separate component is shown detached to demonstrate modularity. <p><b>COMPONENTS</b></p> <p><b>CONNECTORS</b></p> <p><b>NON-RIGID CONNECTORS</b></p> - Impossibility to prepare two abutments for a partial FDP with a common path of placement - Segment a large FPD into shorter components that are easier to replace or repair individually - Prevent the stresses that potentially result from mandibular flexure   #### Functional Benefits - Accommodates cases where a common path of placement between abutments is impossible. - Facilitates easier repair or replacement by segmenting large prostheses. - **Stress Prevention**: Helps prevent stresses that potentially result from mandibular flexure. Schematic diagram illustrating the biomechanical function of non-rigid connectors. It depicts a mandible with red arrows indicating divergent forces from abutment teeth and blue curved arrows showing how the connector allows movement to prevent stress concentration during mandibular flexure. Clinical photograph of a dental model demonstrating a segmented Fixed Partial Denture (FPD). The image shows two distinct metal frameworks connected by a non-rigid joint in the posterior region, visually confirming the concept of segmenting a large FPD into shorter components for easier repair or replacement as described in the text. # Functional Mandibular Deformation in Edentulous Subjects Treated with Dental Implants Hind H. Abdel-Latif, BDS, MSc, PhD^a John A. Hobkirk, Dr Med HC, PhD, BDS, FDS RCS (Eng), FDS RCS (Edin)^b John P. Kelleway, LIBST, RDT^c Int J Prosthodont. 2000 --- ## Torsion | Medial Convergence | Corporal Rotation | Dorsoventral Shear | | :--- | :--- | :--- | | | | | | • 70 to 780 μm<br>• Commencement of opening<br>• After 28% of maximum opening | • Power stroke of mastication<br>• Opening and closing of the jaw | • Unilateral mastication<br>• Opening and closing of the jaw |    #### Torsion Types and Characteristics 1. **Medial Convergence** - 70 to 780 μm - Occurs at commencement of opening (after 28% of maximum opening) 2. **Corporal Rotation** - Occurs during power stroke of mastication - Occurs during opening and closing of the jaw 3. **Dorsoventral Shear** - Occurs during unilateral mastication - Occurs during opening and closing of the jaw Clinical photograph of a mandibular cast demonstrating 'Medial Convergence'. Two black arrows point inward towards the central incisor region. Associated text indicates this deformation is 70 to 780 μm in magnitude, occurs at the commencement of opening, and happens after 28% of maximum opening. Clinical photograph of a mandibular cast demonstrating 'Corporal Rotation'. A curved arrow indicates a rotational movement around the posterior aspect of the ramus. Associated text links this motion to the power stroke of mastication and opening/closing of the jaw. Clinical photograph of a mandibular cast demonstrating 'Dorsoventral Shear'. Vertical arrows indicate vertical displacement: an upward arrow on the left side and a downward arrow on the right side. Associated text notes this occurs during unilateral mastication and opening/closing of the jaw. **Components** **THE UNIVERSITY OF WESTERN AUSTRALIA** | **Oral Health Centre of Western Australia** **CANTILEVER** • Only one side of the pontic is attached to a retainer • Replace one tooth **Assess** • Teeth • Abutment vitality • Opposing occlusion • Edentulous ridge • Esthetic   #### Definition - Only one side of the pontic is attached to a retainer. - Typically used to replace one tooth. #### Assessment Criteria - Condition of teeth - Abutment vitality - Opposing occlusion - Edentulous ridge status - Aesthetic requirements Clinical photo of an anterior dentition showing a missing central incisor (edentulous space) with adjacent teeth. This visual demonstrates the clinical context for a cantilever pontic, which is used to replace one tooth. Clinical photo of a posterior dentition showing a cantilever fixed partial denture. The image displays a metal framework where only one end is attached to abutment teeth, visually demonstrating the 'one side attached' definition provided in the text. # Components ## The University of Western Australia | Oral Health Centre of Western Australia # Ten-year survival of anterior all-ceramic resin-bonded fixed dental prostheses Matthias Kern ¹, Martin Sasse Affiliations + expand PMID: 21935512 DOI: [10.3290/j.jad.a22096](10.3290/j.jad.a22096) ### Abstract **Purpose:** To evaluate the long-term outcome of all-ceramic resin-bonded fixed dental prostheses (RBFDPs) made with a two-retainer design or a cantilever single-retainer design. **Materials and methods:** Overall, 38 anterior RBFDPs were made from a glass-infiltrated alumina ceramic (In-Ceram). Sixteen RBFDPs had a two-retainer design, while 22 RBFDPs had a cantilever single-retainer design. Phosphate monomer containing luting agents were used either after silica coating and silanation or after air-abrasion only. The mean observation time in the two-retainer group was 120.2 months and in the single-retainer group 111.1 months. **Results:** No restoration debonded. In the two-retainer group unilateral and bilateral fractures of the connectors occurred. In the case of unilateral fracture, the pontic remained in situ as a cantilever RBFDP for several years. In the single-retainer group, only one FDP fractured and was lost 48 months after insertion. The 10-year survival rate was 73.9% in the two-retainer group and 94.4% in the single-retainer group. When unilateral fracture of a FDP was taken as a criterion for failure, the 10-year survival rate decreased to 67.3% in the two-retainer group. **Conclusion:** Cantilever all-ceramic RBFDPs are an adequate alternative to two-retainer RBFDPs. #### Study: Ten-year Survival of Anterior All-Ceramic Resin-Bonded FDPs - **Design Comparison**: Evaluated two-retainer designs vs. cantilever single-retainer designs. - **Survival Rates**: - **Single-retainer group**: 94.4% survival rate over 10 years. - **Two-retainer group**: 73.9% survival rate (decreased to 67.3% if unilateral fracture was considered failure). - **Findings**: In the two-retainer group, unilateral and bilateral fractures of the connectors occurred. In the single-retainer group, only one FDP fractured. - **Conclusion**: Cantilever all-ceramic resin-bonded FDPs are an adequate alternative to two-retainer designs. **Components** **CANTILEVER** The University of Western Australia | Oral Health Centre of Western Australia     Components Clinical photo of a cantilever dental bridge showing the pontic and abutment teeth from an occlusal view. Clinical photo of a cantilever dental bridge viewed from the buccal aspect, displaying the crowns on the supporting tooth structure. Dental radiograph (X-ray) showing the internal structure of a cantilever bridge with two distinct radiopaque units corresponding to the crowns. Laboratory photograph of a cantilever bridge model demonstrating the connection between the pontic and the abutment crown. The University of Western Australia Oral Health Centre of Western Australia # Components **Careful selection of cases!!!** Review Article **Assessment of Various Factors for Feasibility of Fixed Cantilever Bridge: A Review Study** ***Potentially*** favorable situations: * **Anterior > Posterior** (Anterior open bite ideal. Excessive overlap between maxillary and mandibular teeth is bad due to excursive movements. Replacement of lateral incisor with canine favourable) * **Vital > Non vital** (Thought to be less susceptible to root fracture) **FIGURE 3:** Failed posterior cantilever bridge due to fractured premolar abutment. **FIGURE 4:** Fractured 2nd premolar (abutment next to pontic).   #### Favorable Clinical Situations - **Anterior vs. Posterior**: Anterior is generally more favorable. An anterior open bite is ideal; excessive overlap is problematic due to excursive movements. Replacing a lateral incisor using a canine abutment is favorable. - **Vitality**: Vital abutments are preferred as they are thought to be less susceptible to root fracture than non-vital teeth. #### Risks - Posterior cantilever bridges carry a higher risk of failure, such as fractured premolar abutments. Clinical photo (FIGURE 3): Failed posterior cantilever bridge due to fractured premolar abutment. Clinical photo (FIGURE 4): Fractured 2nd premolar (abutment next to pontic). # Components **THE UNIVERSITY OF WESTERN AUSTRALIA** | **Oral Health Centre of Western Australia** ## CANTILEVER Adding a second abutment may lessen the forces experienced by the most distal abutment, and help in rotational forces. However greater challenge to the cement on the further abutment crown **Figure 1:** Creation of a class 1 lever by a cantilevered FPD [3]. Abd Elghany MH. Cantilevered Fixed Partial Denture. *EC Dental Science*. 2020;19:122-30.   #### Biomechanical Dynamics - **Lever Systems**: A cantilevered FPD can create a Class 1 lever. - **Multi-Abutment Support**: Adding a second abutment may lessen the forces experienced by the most distal abutment and assist with rotational forces. - **Cementation Challenge**: Using multiple abutments increases the challenge to the cement seal on the abutment crown furthest from the pontic. Medical diagram illustrating the mechanical forces on a dental cantilever bridge. It includes two separate views: a side view showing tilting/rotation of an abutment tooth under force F, and an occlusal (top-down) view showing rotation around the central axis. Labels include 'Tilting/rotation', 'F' (Force), and 'Rotation'. The visual demonstrates how rotational forces are applied to the teeth in a fixed partial denture setup. Figure 1 labeled illustration showing the creation of a Class 1 lever by a cantilevered Fixed Partial Denture (FPD). The image depicts three molar roots with a fulcrum point indicated between the middle and posterior root. Red arrows indicate upward and downward forces acting on the anterior and posterior teeth respectively, demonstrating the lever mechanics described in the caption. **Components** **CANTILEVER** THE UNIVERSITY OF WESTERN AUSTRALIA Oral Health Centre of Western Australia     Components Clinical photo of a dental model showing a cantilever bridge. A red circle highlights the connector area between the pontic and the abutment tooth on the left side. Intraoral clinical photo demonstrating a cantilever fixed partial denture. The image shows the posterior teeth with crowns and the anterior tooth acting as the abutment for the cantilever extension. Intraoral clinical photo showing a cantilever restoration in progress or completed. A red circle highlights the specific abutment tooth supporting the cantilever structure. Intraoral clinical photo providing another view of the cantilever arrangement, focusing on the occlusal surfaces and the connection point of the prosthesis. Thanks for listening! Thank you! Thanks for listening! Thank you! [^1]: Original PDF page 1: [[L1 Fixed Dental Prosthesis.pdf#page=1|L1 Fixed Dental Prosthesis, p.1]] [^2]: Original PDF page 2: [[L1 Fixed Dental Prosthesis.pdf#page=2|L1 Fixed Dental Prosthesis, p.2]] [^3]: Original PDF page 3: [[L1 Fixed Dental Prosthesis.pdf#page=3|L1 Fixed Dental Prosthesis, p.3]] [^4]: Original PDF page 4: [[L1 Fixed Dental Prosthesis.pdf#page=4|L1 Fixed Dental Prosthesis, p.4]] [^5]: Original PDF page 5: [[L1 Fixed Dental Prosthesis.pdf#page=5|L1 Fixed Dental Prosthesis, p.5]] [^6]: Original PDF page 6: [[L1 Fixed Dental Prosthesis.pdf#page=6|L1 Fixed Dental Prosthesis, p.6]] [^7]: Original PDF page 7: [[L1 Fixed Dental Prosthesis.pdf#page=7|L1 Fixed Dental Prosthesis, p.7]] [^8]: Original PDF page 8: [[L1 Fixed Dental Prosthesis.pdf#page=8|L1 Fixed Dental Prosthesis, p.8]] [^9]: Original PDF page 9: [[L1 Fixed Dental Prosthesis.pdf#page=9|L1 Fixed Dental Prosthesis, p.9]] [^10]: Original PDF page 10: [[L1 Fixed Dental Prosthesis.pdf#page=10|L1 Fixed Dental 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