**The University of Western Australia** **Oral Health Centre of Western Australia** ## **MOUTH PREPARATION** **FOR RPD** Dr Matsubara #### Clinical Overview This documentation outlines the protocols for mouth preparation required for Removable Partial Dentures (RPD) at the Oral Health Centre of Western Australia, University of Western Australia. #### Presentation Details - **Institution:** The University of Western Australia - **Department:** Oral Health Centre of Western Australia - **Lead Clinician:** Dr. Matsubara # **Mouth Preparation** **THE UNIVERSITY OF WESTERN AUSTRALIA** | **Oral Health Centre of Western Australia** - A series of procedures executed to repair, alter and/or protect the remaining teeth. - To prevent or redirect adverse forces that may affect the supporting teeth, periodontal tissues and residual alveolar bone crest, obtaining retention and support for a removable prosthesis for the maximum period of time. - Mouth preparation includes all operations which re-establish or maintain the health of the abutment teeth, supporting structures, and ridge tissues and which make possible a simpler design for the prosthesis. Mouth preparation consists of a series of procedures executed to repair, alter, and/or protect the remaining teeth. #### Clinical Objectives - Prevent or redirect adverse forces that may affect the supporting teeth, periodontal tissues, and residual alveolar bone crest. - Obtain retention and support for a removable prosthesis for the maximum period of time. - Re-establish or maintain the health of the abutment teeth, supporting structures, and ridge tissues. - Facilitate a simpler design for the prosthesis. # **Mouth Preparation** **The University of Western Australia** | **Oral Health Centre of Western Australia** Two Stages: * 1st stage - Clinical interventions to establish a healthy condition of remaining teeth and related tissues. These include maneuvers to eliminate the factors that harm hard tissues (teeth and bones) and soft tissues (periodontium, mucosa, gingiva) Mouth preparation is divided into two stages. #### First Stage Overview The first stage involves clinical interventions to establish a healthy condition of remaining teeth and related tissues. These include maneuvers to eliminate the factors that harm: - Hard tissues (teeth and bones) - Soft tissues (periodontium, mucosa, and gingiva) # Mouth Preparation ### Two Stages: - 1st stage - Clinical interventions to establish a healthy condition of remaining teeth and related tissues #### Emergency and Control Phase – Eliminate pain, infection and inflammation - Periodontal treatment - Endodontic treatment - Restorative treatment* - Oral surgeries (pre-prosthetic surgeries) - Orthodontic treatment - Occlusal adjustments #### Holding phase – Preserve residual dentition  The first stage of clinical interventions focuses on establishing a healthy environment through specific phases of care. #### Emergency and Control Phase This phase aims to eliminate pain, infection, and inflammation through: - Periodontal treatment - Endodontic treatment - Restorative treatment - Oral surgeries (pre-prosthetic surgeries) - Orthodontic treatment - Occlusal adjustments #### Holding Phase - Focuses on the preservation of the residual dentition. A text-based procedure outline detailing the 'Emergency and Control Phase' of mouth preparation. The visual lists specific clinical interventions required to eliminate pain, infection, and inflammation, including periodontal treatment, endodontic treatment, restorative treatment, oral surgeries (pre-prosthetic), orthodontic treatment, and occlusal adjustments. It also outlines the subsequent 'Holding phase' for preserving residual dentition. **Mouth Preparation** Two Stages: 2nd stage - Interventions on the remaining teeth aiming at improving biomechanical conditions between supporting teeth and metal structure. Reconstructive Phase - Replace lost tissues, stabilize occlusion - Rest seat preparation - Tooth recontouring (height of contour, guiding planes) After: **Maintenance Phase** – Prevention of further breakdown #### Second Stage Clinical Interventions This stage involves interventions on the remaining teeth aiming at improving biomechanical conditions between supporting teeth and the metal structure. #### Reconstructive Phase Designed to replace lost tissues and stabilize occlusion through: - Rest seat preparation - Tooth recontouring (adjusting height of contour and creating guiding planes) #### Maintenance Phase Following the active preparation stages, this phase focuses on the prevention of further breakdown. # Mouth Preparation ## 1st stage Periodontal Treatment **Aims:** 1) **Control microbiological factor**: calculus removal, plate control, oral hygiene orientation, control of iatrogenic factors 2) **Provide comfort to the patient**: pain and bleeding control, and improvement in gingival appearance   #### Objectives of Initial Periodontal Therapy 1. **Control of Microbiological Factors** - Removal of calculus - Plaque control and oral hygiene orientation - Management of iatrogenic factors 2. **Patient Comfort and Health** - Control of pain and bleeding - Improvement in gingival appearance Clinical intraoral photograph showing a patient's mouth with significant periodontal pathology. The image displays severe gingival inflammation (redness and swelling) and heavy accumulation of supragingival calculus on the teeth, corresponding to the 'Periodontal Treatment' context. Dental radiograph (X-ray) displaying the roots of several posterior teeth. It illustrates the underlying bone structure and tooth anatomy relevant to the 'Mouth Preparation' procedure, likely used for diagnostic assessment prior to treatment. # **Mouth Preparation** ## 1st stage **Periodontal Treatment** - **Probe** - **Supra and sub-gingival debridement**     #### Clinical Procedures - Periodontal probing - Supra-gingival and sub-gingival debridement Clinical photo showing periodontal treatment step: a dental probe is inserted into the gingival sulcus near the upper anterior teeth to demonstrate probing for pocket depth assessment. Clinical photo showing a dental scaler or curette being used for sub-gingival debridement on the lower right posterior teeth area, demonstrating removal of calculus from the root surface. Clinical photo showing a periodontal probe with black markings indicating millimeter depth, measuring gingival pocket depth between two lower anterior teeth with visible inflammation. Clinical photo showing a dental instrument performing supragingival and subgingival debridement on an upper molar tooth, removing plaque/calculus deposits from the gumline and root surface. Mouth Preparation **THE UNIVERSITY OF** **WESTERN** **AUSTRALIA** Oral Health Centre of Western Australia   Oral Health Centre of Western Australia Clinical intraoral photograph of the lower anterior dentition showing multiple teeth with extensive carious lesions, decayed structures, and gingival inflammation. The image illustrates a pre-treatment state requiring mouth preparation. Series of dental radiographs (periapical views) displaying the mandibular anterior region. Multiple images show varying degrees of root structure, bone levels, and restorations, including what appear to be endodontically treated teeth or posts in some views. **Headline**: Mouth Preparation **Subheading**: Scaling and root planing, crown lengthening  #### Periodontal Interventions - Scaling and root planing - Crown lengthening Clinical photo showing a close-up of the lower anterior teeth and gingiva during mouth preparation. The image demonstrates scaling and root planing with visible bleeding (redness) along the gumline, indicating active treatment. Black marking lines are drawn on the cervical third of each tooth to indicate the planned crown lengthening margin or reference points for contour reduction. **Mouth Preparation** Scaling and root planing, crown lengthening    #### Periodontal Interventions - Scaling and root planing - Crown lengthening Clinical photo of a lower jaw showing teeth with black sutures (stitches) visible in the gum tissue, indicating an immediate post-operative state following scaling and root planing or crown lengthening. Clinical photo of the upper anterior teeth showing metal sub-structures on the left and right canines, likely representing retained tooth fragments or crowns after preparation. Clinical photo of the upper anterior teeth showing smooth, prepared enamel surfaces, demonstrating the result of the mouth preparation process. Mouth Preparation THE UNIVERSITY OF WESTERN AUSTRALIA Oral Health Centre of Western Australia   Oral Health Centre of Western Australia Dental radiograph showing a tooth with extensive decay and possible root canal treatment, surrounded by other teeth in the jaw. The image is part of a 'Mouth Preparation' presentation from The University of Western Australia Oral Health Centre. Dental radiograph displaying multiple teeth with fillings or crowns, likely part of a dental restoration case. This image is also from the same 'Mouth Preparation' presentation context. **Mouth Preparation** THE UNIVERSITY OF WESTERN AUSTRALIA | Oral Health Centre of Western Australia 1st stage **Endodontic Treatment** Pulp necrosis Abscess (endodontic, periodontal or combination)    #### Indications for Treatment - Pulp necrosis - Abscess (endodontic, periodontal, or combination) Clinical photo of the oral cavity showing a patient's upper anterior teeth. A dental instrument is visible entering the gingival sulcus at the gumline between the central incisors, demonstrating the procedure for mouth preparation. Radiograph (X-ray) image showing a tooth with an endodontic treatment in progress or completed, displaying a root canal filling material within the canal space. Radiograph (X-ray) image showing another tooth with a root canal filling, likely illustrating the result of the Endodontic Treatment mentioned in the text. # Mouth Preparation ### 1st stage Endodontic Treatment **Tooth with root canal treatment:** a) Completely filled canals, without radiographic signs of apical periodontitis b) Completely filled canals, but with radiographic signs of apical periodontitis c) Root canal partially filled, with no signs of apical periodontitis d) Root canal partially filled, with apical periodontitis  #### Assessment of Existing Root Canal Treatment 1. Completely filled canals, without radiographic signs of apical periodontitis 2. Completely filled canals, but with radiographic signs of apical periodontitis 3. Root canal partially filled, with no signs of apical periodontitis 4. Root canal partially filled, with apical periodontitis Composite figure containing four dental radiographs labeled A, B, C, and D, illustrating different stages of root canal treatment outcomes. Panel A shows a tooth with completely filled canals without signs of apical periodontitis (healthy periapical bone). Panel B displays a tooth with completely filled canals but with radiographic evidence of apical periodontitis (radiolucency at the root tip). Panel C presents a tooth with partially filled canals and no signs of apical periodontitis. Panel D depicts a tooth with partially filled canals accompanied by visible apical periodontitis. The images serve to visually correlate the text descriptions of endodontic treatment conditions. **Mouth Preparation** ## 1st stage ### Endodontic Treatment **Tooth with root canal treatment:** Completely filled canals, without radiographic signs of apical periodontitis 1. Asymptomatic on percussion or palpation 2. When the root canal treatment was performed 3. Quality of the obturation #### Evaluation of Successful Obturation For a tooth with root canal treatment featuring completely filled canals and no radiographic signs of apical periodontitis, evaluate the following: 1. Asymptomatic on percussion or palpation 2. When the root canal treatment was performed 3. Quality of the obturation # Mouth Preparation The University of Western Australia Oral Health Centre of Western Australia 1st stage Restorative Treatment • Stablish a healthy oral environment through the restoration of decayed tissues, replacement of restorations • Supporting tooth: Adequate restorations that will receive rest seat – enough depth and width. Rest seat 1 mm of amalgam     #### Clinical Objectives - Establish a healthy oral environment through the restoration of decayed tissues and the replacement of failing restorations. - Ensure supporting teeth have adequate restorations capable of receiving rest seats with sufficient depth and width. #### Rest Seat Requirements - Rest seats placed in amalgam restorations require a minimum thickness of 1 mm of material. Intraoral radiograph showing multiple posterior teeth with large, multi-surface restorations. The image demonstrates the 'restoration of decayed tissues' mentioned in the text. Dental X-ray showing a molar tooth with significant caries and an existing restoration. This visual supports the text regarding the need for restoring decayed tissues to establish a healthy oral environment. Anatomical diagram of a molar tooth illustrating a 'Rest seat' (labeled with red arrow) prepared into the occlusal surface. A second label indicates '1 mm of amalgam' thickness required at the base of the preparation. Clinical photograph of a molar tooth showing a completed dental restoration. Black brackets outline specific areas on the silver-colored filling, likely indicating the depth or location of the 'rest seat' described in the text. **Mouth Preparation** **1st stage** **Restorative Treatment** THE UNIVERSITY OF WESTERN AUSTRALIA Oral Health Centre of Western Australia  Mouth Preparation 1st stage Restorative Treatment Clinical photo showing the upper dental arch during mouth preparation (1st stage Restorative Treatment). Visible features include a metal framework or matrix bands across multiple posterior teeth, likely for impression taking or temporary restoration. The image demonstrates restorative treatment progress with metallic structures in place on several molars and premolars. # **Mouth Preparation** **THE UNIVERSITY OF WESTERN AUSTRALIA** | **Oral Health Centre of Western Australia** 1st stage Oral surgeries **•** Tooth extraction, periodontal and endodontic surgeries **•** Pre-prosthetic surgery: Surgical procedure that modify the oral anatomy to facilitate retention and seating of dentures > **Glossary of prosthodontic terms**: surgical procedures designed to facilitate fabrication or to improve the prognosis of prosthodontic care  #### Clinical Interventions - Tooth extraction, periodontal and endodontic surgeries - Pre-prosthetic surgery: Surgical procedure that modify the oral anatomy to facilitate retention and seating of dentures #### Definition of Pre-Prosthetic Surgery According to the **Glossary of Prosthodontic Terms**, these are surgical procedures designed to facilitate fabrication or to improve the prognosis of prosthodontic care. Text box styled as a definition table or glossary entry. Contains the header 'Glossary of prosthodontic terms' followed by the definition: 'surgical procedures designed to facilitate fabrication or to improve the prognosis of prosthodontic care'. This visual structure separates the definition from surrounding text. Mouth Preparation - Extractions - Removal of residual roots - Removal of mandibular tori - Removal of exostosis, hyperplastic tissue, high muscle attachments - Round of sharp bony spines and knife-edge ridges - Reduction of maxillary tuberosity volume <br> The University of Western Australia Oral Health Centre of Western Australia     #### Common Surgical Procedures - Extractions - Removal of residual roots - Removal of mandibular tori - Removal of exostosis, hyperplastic tissue, and high muscle attachments - Rounding of sharp bony spines and knife-edge ridges - Reduction of maxillary tuberosity volume Clinical photo of the mandibular vestibule showing a bony ridge (likely a torus or exostosis) under retraction. Relevant to 'Removal of mandibular tori' and 'Removal of exostosis'. Clinical photo of the maxillary anterior region showing prominent gingival tissue and teeth, possibly illustrating an area requiring 'Extractions', 'Removal of residual roots', or addressing 'hyperplastic tissue'. Clinical photo of the maxillary arch (palatal view) showing a large, bulbous bony prominence at the midline (maxillary tuberosity). Directly illustrates 'Reduction of maxillary tuberosity volume'. Clinical photo of the floor of the mouth (mandibular lingual aspect) showing irregular soft tissue growths or bony projections. Relevant to 'Removal of exostosis, hyperplastic tissue' and 'Round of sharp bony spines'. **Mouth Preparation** THE UNIVERSITY OF WESTERN AUSTRALIA Oral Health Centre of Western Australia - Extractions - Removal of residual roots - Removal of mandibular tori - Removal of exostosis, hyperplastic tissue, high muscle attachments - Round of sharp bony spines and knife-edge ridges - Reduction of maxillary tuberosity volume   #### Common Surgical Procedures - Extractions - Removal of residual roots - Removal of mandibular tori - Removal of exostosis, hyperplastic tissue, and high muscle attachments - Rounding of sharp bony spines and knife-edge ridges - Reduction of maxillary tuberosity volume Clinical intraoral photograph showing the maxillary arch with a visible palatal torus (bony growth) on the roof of the mouth. The image corresponds to the slide item 'Removal of mandibular tori' and demonstrates the anatomical structure requiring reduction. Clinical photograph of a translucent dental impression tray or study model. This visual aids in understanding the physical space and volume within the oral cavity relevant to the text point 'Reduction of maxillary tuberosity volume'. - **Mouth Preparation** - Maintenance of non-vital residual root - **Submerged** - **Non-submerged** - Alveolar ridge preservation   #### Residual Root Management and Ridge Preservation - Maintenance of non-vital residual root - Submerged - Non-submerged - Alveolar ridge preservation Medical diagram illustrating a 'Submerged' non-vital residual root. The image shows the tooth crown covered by gum tissue (represented by a curved line), with the root tip positioned below the alveolar bone level. Bone fragments are visible in the surrounding area. Medical diagram illustrating a 'Non-submerged' non-vital residual root. The image shows the tooth crown exposed above the gum line, with the root tip positioned within the alveolar bone level. Bone fragments are visible in the surrounding area. **Mouth Preparation** The University of Western Australia | Oral Health Centre of Western Australia 1st stage **Orthodontic Treatment** Teeth position may prevent the ideal design of the RPD Most frequent indication: * **Molar leaning towards the edentulous area** * **Tooth rotation** * **Labial migration of anterior teeth**   Teeth position may prevent the ideal design of the Removable Partial Denture (RPD). #### Common Indications for Orthodontic Intervention - **Molar leaning towards the edentulous area**: Correcting the angulation of tilted abutment teeth to improve the path of insertion and loading. - **Tooth rotation**: Realigning rotated teeth to facilitate proper clasp positioning and seating of the prosthesis. - **Labial migration of anterior teeth**: Addressing drifted or flared anterior teeth to improve esthetics and structural stability. Anatomical diagram showing the occlusal view of posterior teeth (molars and premolars) illustrating specific malpositions. The image depicts molar leaning towards the edentulous area, tooth rotation, and labial migration of anterior teeth, corresponding to the text 'Most frequent indication' on the left. Clinical intraoral photograph showing a patient's dentition with an orthodontic appliance in place. The image demonstrates the alignment issues mentioned in the text, such as labial migration of anterior teeth or rotation, within the context of mouth preparation for RPD design. The University of WESTERN AUSTRALIA Oral Health Centre of Western Australia     Clinical intraoral photograph showing the mandibular posterior dentition. It demonstrates a tooth with significant carious destruction (cavity) on the occlusal surface and adjacent teeth, serving as the baseline for mouth preparation. Dental radiograph (X-ray) of the mandibular molar region. The image reveals the internal structure of the teeth, including the root canals and bone levels, providing diagnostic context for the procedure shown in the clinical photos. Clinical intraoral photograph displaying the 'Mouth Preparation' stage. A metal matrix band is visible securing a temporary restoration or impression material onto the prepared tooth to shape the cavity walls before the final crown is placed. Close-up clinical intraoral photograph focusing on the prepared tooth within the dental arch. It clearly shows the outline form created by the temporary material and the matrix band, demonstrating the preparation depth and margin location. **Mouth Preparation** **1st stage** **Occlusal Adjustment** THE UNIVERSITY OF WESTERN AUSTRALIA | Oral Health Centre of Western Australia   Mouth Preparation 1st stage Clinical photo showing a close-up lateral view of the patient's lower left posterior teeth and upper anterior teeth. The image highlights significant dental decay (caries) on the occlusal surfaces and interproximal areas of several molars, along with gingival inflammation. Clinical photo showing a frontal view of the patient's dentition. A red curved line is drawn across the arch to indicate the occlusal plane or contact points between the upper and lower teeth, relevant to the 'Occlusal Adjustment' text in the slide title. # **Mouth Preparation** **1st stage** **Occlusal Adjustment**   Mouth Preparation 1st stage Clinical photo of dental stone models showing occlusal adjustment. The image displays upper and lower teeth in contact with a red line highlighting the contact area between the molars, indicating the region of interest for occlusal adjustment. Clinical photo of dental stone models showing occlusal adjustment from a different angle. Similar to the first image, it features upper and lower teeth with a red line marking the occlusal contact area for adjustment purposes. Mouth Preparation **The University of Western Australia** Oral Health Centre of Western Australia 1st stage Occlusal Adjustment  Mouth Preparation 1st stage Clinical photo of a dental study model (cast) showing the mandibular arch. Two posterior teeth on either side are prepared with visible reduction in crown height, indicated by lighter-colored material or preparation depth compared to adjacent natural teeth. The image is framed with a red border and labeled 'Occlusal Adjustment' as part of the '1st stage' of mouth preparation. **Mouth Preparation** 1st stage **Occlusal Adjustment** **THE UNIVERSITY** OF **WESTERN** **AUSTRALIA** **Oral Health Centre** of Western Australia   Mouth Preparation 1st stage Clinical photo showing a dental cast with an occlusal adjustment being performed on the lower arch. The image displays the upper and lower teeth in occlusion, with a darkened area indicating the tooth surface that has been adjusted or prepared. Clinical photo showing another view of a dental cast undergoing occlusal adjustment. Similar to the first image, it depicts the alignment of upper and lower teeth with a specific focus on the adjusted region in the lower jaw. Original Text: **Vit** **Am** | **Exc** **Olu** | **Ere** | **Per** | **Ar** **Tes** | **Seek Wisdom** | **The University of Western Australia** | **Oral Health Centre of Western Australia** | Mouth Preparation   Mouth Preparation Clinical photo showing a dental cast of the maxillary (upper) arch from an occlusal view. The teeth are prepared for dentures, with significant reduction in crown height and rounded surfaces. This is relevant to 'Mouth Preparation'. Clinical photo showing a dental cast of the mandibular (lower) arch from an occlusal view. Similar to the upper arch, the teeth have been reduced in preparation for a complete denture prosthesis. Mouth Preparation THE UNIVERSITY OF WESTERN AUSTRALIA | Oral Health Centre of Western Australia   Mouth Preparation Clinical photo showing a dental study model with full upper and lower teeth in occlusion, representing the pre-preparation state for mouth preparation. Clinical photo showing a dental study model after tooth reduction (mouth preparation), with visible flat surfaces on anterior teeth and an open bite between upper and lower arches. Mouth Preparation THE UNIVERSITY OF WESTERN AUSTRALIA Oral Health Centre of Western Australia   Mouth Preparation Clinical photo of a maxillary dental cast showing the occlusal view with prepared teeth indicated by circular markings. Clinical photo of a mandibular dental cast showing the occlusal view with prepared teeth indicated by circular markings. **Mouth Preparation** THE UNIVERSITY OF WESTERN AUSTRALIA Oral Health Centre of Western Australia     Mouth Preparation Clinical photo of a maxillary dental cast showing red wax or material placed on the posterior teeth (molars and premolars) bilaterally, likely representing prepared areas for denture fabrication. Clinical photo of a mandibular dental cast with red wax applied to the left posterior region (premolar/molar area), indicating preparation site for prosthesis. Lateral view clinical photo of upper and lower dental casts in occlusion, showing red wax extending across multiple posterior teeth on both arches — demonstrating interarch relationship during mouth preparation. Lateral view clinical photo of upper and lower dental casts in occlusion, showing red wax primarily on the right posterior region of the lower arch, illustrating localized preparation for prosthetic work. # Mouth Preparation Mini implants The University of Western Australia Oral Health Centre of Western Australia Paccini et al. 2016    Mouth Preparation Mini implants Paccini et al. 2016 Clinical photo showing a close-up of the upper left posterior teeth with fixed orthodontic brackets (metal and pink) and an archwire. A mini implant is visible attached to the gum tissue between the premolar and molar region, connected via a transparent attachment to a metal bracket on the first molar. Clinical photo showing the upper right posterior dentition with fixed orthodontic appliances (brackets and archwires). Two mini implants are inserted into the alveolar ridge near the molars, connected by clear acrylic attachments to the orthodontic wire system. Technical diagram illustrating three types of dental mini implants of varying lengths: 10 mm, 13 mm, and 15 mm. The implants have a diameter of Ø 2.5mm as indicated in the top-left corner. Each implant shows a threaded body and a smooth connection head. # Mouth Preparation Top right corner logos: THE UNIVERSITY OF WESTERN AUSTRALIA Oral Health Centre of Western Australia 2nd stage Adjust and prepare the supporting teeth - Rest seat preparation - Tooth recontouring (height of contour, guiding planes)  During the second stage of mouth preparation, the supporting teeth are adjusted and prepared through the following procedures: - Rest seat preparation - Tooth recontouring, including adjustments to the height of contour and the creation of guiding planes Text-only slide content listing the '2nd stage' of Mouth Preparation. It outlines steps to 'Adjust and prepare the supporting teeth', specifically detailing 'Rest seat preparation' and 'Tooth recontouring (height of contour, guiding planes)'. No visual diagrams or figures are present. **Mouth Preparation** 2nd stage Rest seat preparation The University of Western Australia | Oral Health Centre of Western Australia    #### Rest Seat Preparation Initial focus of the second stage involves the preparation of rest seats to provide support for the removable partial denture. A composite figure showing two views of a molar tooth preparation: an occlusal view with a dashed line indicating the margin and an axial cross-section showing the internal anatomy. Below is a clinical photo of a prepared tooth with amalgam filling material. A schematic diagram illustrating the outline of a prepared tooth (likely a canine or premolar) with a rest seat preparation on the mesial aspect, indicated by stippled shading. A clinical photograph of a tooth with a prepared rest seat on the lingual surface, likely for a crown or bridge abutment. # Mouth Preparation **2nd stage** **Tooth recontouring** * height of contour * guiding planes   #### Tooth Recontouring Components Tooth recontouring involves two primary modifications: - Adjusting the height of contour - Establishing guiding planes Clinical photo showing a dental cast with a metal framework and teeth. The image illustrates the concept of 'height of contour' as part of tooth recontouring. Clinical photo showing another angle of a dental cast with a metal framework. This image demonstrates the placement of 'guiding planes' on the prepared teeth. **Mouth Preparation** THE UNIVERSITY OF WESTERN AUSTRALIA Oral Health Centre of Western Australia 2nd stage **Drop down the height of contour** Creating guiding planes Cut tooth structure     #### Height of Contour and Guiding Planes Procedures for recontouring include: - Dropping down the height of contour - Creating guiding planes by cutting tooth structure Clinical photo of a dental model showing the buccal aspect of a molar. It displays the '2nd stage' of mouth preparation with a red dotted line indicating the original height of contour and a blue solid line showing the new, lowered height of contour to create guiding planes. Clinical photo of a dental model showing the lingual/palatal aspect of a tooth. It illustrates the cut lines (red dotted) for creating guiding planes on the proximal surfaces, corresponding to the text instruction 'Cut tooth structure'. Clinical photo of a dental model showing the mesial aspect of a molar. It visualizes the 'Drop down the height of contour' step with distinct red and blue lines marking the modification of the tooth's contour. Close-up clinical photo of a dental handpiece cutting into a prepared tooth structure, demonstrating the physical execution of the 'Cut tooth structure' step described in the slide. <!-- Transfer tooth reduction for prosthodontics -->   Transfer tooth reduction for prosthodontics Clinical photo showing a dental stone model of teeth with red wax outlines indicating preparation margins. A metal dental bur is shown actively cutting the tooth structure to demonstrate the physical reduction step. Clinical photo showing a close-up view of a patient's mouth during a dental procedure. Gloved hands are using a dental instrument (likely a diamond bur) to reduce the tooth structure in accordance with the planned preparation. Mouth Preparation The University of Western Australia Oral Health Centre of Western Australia **2nd stage** Transfer tooth reduction from model to mouth • **Free hand**   #### Free Hand Technique One method for transferring tooth reduction from the model to the mouth is performed free hand. Clinical photo demonstrating the 'Free hand' technique for mouth preparation. The image shows a gloved hand retracting the cheek to expose a tooth being treated with a dental rotary instrument. Visible is the cutting action on the tooth structure and the gingival tissue. Clinical photo demonstrating the 'Free hand' technique from a different angle or stage. A gloved hand holds a dental instrument against a prepared tooth while another gloved finger retracts the adjacent cheek tissue. Mouth Preparation 2nd stage Transfer tooth reduction from model to mouth • **Free hand**   #### Free Hand Technique Transferring tooth reduction from the model to the mouth using the free hand method. Clinical photo showing a dental procedure in progress. A gloved hand holds a dental instrument against a prepared tooth inside the patient's mouth, demonstrating the 'Free hand' technique mentioned in the OCR text for transferring tooth reduction. Close-up clinical photo of a prepared tooth (likely a cast model or extracted tooth) held by fingers. The tooth shows distinct horizontal lines representing the depth cuts made during the reduction process, visually corresponding to the 'Transfer tooth reduction' step described in the text. **The University of Western Australia** **Oral Health Centre of Western Australia** Mouth Preparation 2nd stage Transfer tooth reduction from model to mouth * Dura-lay guide     #### Dura-lay Guide Technique Utilizing a Dura-lay guide to transfer tooth reduction from the model to the mouth. Clinical photo showing the first step of tooth reduction on a dental cast. A vertical metal bur is positioned directly onto a specific tooth to demonstrate the cutting depth and angle. Clinical photo illustrating the second step of the procedure. A hand holds a brush with red marking material (Dura-lay guide) over a dental model while a drill operates nearby, demonstrating the transfer process. Clinical photo showing the third step: applying the red Dura-lay guide material to the surface of the tooth on the dental cast using a fine-tipped brush. Clinical photo showing the final step of this stage. The red guide material has been applied to the tooth, outlining the area for preparation before the actual reduction begins in the patient's mouth. # Mouth Preparation **THE UNIVERSITY OF WESTERN AUSTRALIA | Oral Health Centre of Western Australia** 2nd stage Transfer tooth reduction from model to mouth * Dura-lay guide   #### Dura-lay Guide Technique Transferring tooth reduction from the model to the mouth using a Dura-lay guide. Clinical photo showing a dental study model with teeth reduced in red material. Black outline markings are visible on the teeth and gum line, representing the preparation guide or reduction path. Clinical photo showing a close-up of a dental model where a brush is applying red material to the tooth surfaces along black outline guides. This demonstrates the application of the Dura-lay guide for tooth reduction transfer. **Mouth Preparation** 2nd stage Transfer tooth reduction from model to mouth • Dura-lay guide   #### Dura-lay Guide Technique Transferring tooth reduction from the model to the mouth using a Dura-lay guide. Clinical photo showing a dental procedure: a rotary cutting instrument is being used to reduce the tooth structure on a white plaster dental model. Red material simulates soft tissue or gingiva around the teeth. Clinical photo showing the continuation of the dental procedure with the rotary instrument positioned over another tooth on the same plaster model. **Mouth Preparation** **THE UNIVERSITY OF WESTERN AUSTRALIA** Oral Health Centre of Western Australia 2nd stage Transfer tooth reduction from model to mouth * **Dura-lay guide**   #### Dura-lay Guide Technique Transferring tooth reduction from the model to the mouth using a Dura-lay guide. Clinical photo showing a gloved hand holding a red Dura-lay guide positioned over the upper left canine and premolar teeth during the 'Mouth Preparation' procedure. The image demonstrates the transfer of tooth reduction from model to mouth. Clinical photo showing a similar view of the upper left dentition with the red Dura-lay guide in place, illustrating the second stage of mouth preparation where tooth reduction is transferred from the model to the patient's mouth. The University of Western Australia Oral Health Centre of Western Australia Mouth Preparation **2nd stage** Transfer tooth reduction from model to mouth * Dura-lay guide   #### Dura-lay Guide Technique Transferring tooth reduction from the model to the mouth using a Dura-lay guide. Clinical photo showing the 'Dura-lay guide' procedure in the second stage of mouth preparation. An intraoral view displays a dental drill with a bur actively reducing a tooth covered by a red-colored wax or temporary matrix material, demonstrating the transfer of reduction from model to mouth. Clinical photo showing the completed result of the tooth reduction procedure. The image displays the prepared tooth (covered in red material) next to adjacent natural teeth, illustrating the shape and extent of the reduction achieved using the Dura-lay guide.    Clinical photo showing a dental procedure: a red Dura-lay guide is positioned over a tooth while a high-speed dental handpiece (drill) reduces the tooth structure. The image demonstrates the transfer of tooth reduction from model to mouth. Close-up clinical photo of a red Dura-lay guide covering the occlusal surface of an upper molar, demonstrating the guide's fit on the prepared tooth before or during preparation. Clinical photo showing a vertical cross-section of a tooth with a red Dura-lay guide placed over it, illustrating the depth and contour of the planned tooth reduction guided by the material. **Mouth Preparation** **THE UNIVERSITY OF WESTERN AUSTRALIA** | **Oral Health Centre of Western Australia** 2nd stage Transfer tooth reduction from model to mouth * Base plate      #### Base Plate Technique Utilizing a base plate to transfer tooth reduction from the model to the mouth. Clinical photo showing a dental study model with red base plate material mounted on a metal articulator stand. The setup is used for the 'Base plate' stage of mouth preparation. Close-up clinical photo demonstrating the procedure to transfer tooth reduction from model to mouth. A dental instrument (bur) is shown actively cutting into the center of the red base plate material on the model. Hand-held view of the base plate in the second stage of mouth preparation. A hand holds the model while an instrument is inserted into the prepared area of the red material. Clinical photo showing the final result of the reduction process. A white translucent dental appliance or wax pattern is placed over the reduced area on the yellow stone model. Macro close-up photo illustrating the surface detail of the tooth reduction. It shows the texture and depth created by the bur cutting into the pinkish-red material. # Mouth Preparation **The University of Western Australia** Oral Health Centre of Western Australia 2nd stage No retentive area – low height of contour Raising Height of Contour * Prepare an undercut using a bur * Add composite to create undercut * Surveyed crown Insufficient retention The retentive arm has to be at least 1 mm from gingiva  #### Management of Insufficient Retention When there is no retentive area due to a low height of contour, the following methods can be used to raise the height of contour: - Prepare an undercut using a bur - Add composite to create an undercut - Utilize a surveyed crown Note: The retentive arm must be positioned at least 1 mm from the gingiva. Annotated diagram illustrating a dental crown on a tooth. A yellow triangle highlights the 'low height of contour' area near the gum line, labeled as 'No retentive area'. Below this, a red dotted line indicates the path of the retentive arm, which is noted to be 'Insufficient retention' and positioned too close to the gingiva (less than 1 mm). # Mouth Preparation ## The University of Western Australia | Oral Health Centre of Western Australia ### 2nd stage #### Raising Height of Contour Preparing undercut * Create a gentle depression where the tip of the retention arm will be placed * Follow the shape and design of the selected retentive tip   #### Preparing Undercuts - Create a gentle depression where the tip of the retention arm will be placed. - Ensure the preparation follows the shape and design of the selected retentive tip. Clinical close-up photograph demonstrating the 'Raising Height of Contour' step in mouth preparation. It shows a dental bur (drill tip) actively creating a gentle depression on the enamel surface of a tooth, preparing an undercut for a retentive arm. Intraoral clinical photograph showing the facial aspect of anterior teeth. A specific area on the mesial surface of a central incisor is marked with a black circle, indicating the planned location for the undercut preparation mentioned in the text. **Mouth Preparation** THE UNIVERSITY OF WESTERN AUSTRALIA | Oral Health Centre of Western Australia 2nd stage **Raising Height of Contour** Adding composite above the retentive area **Lingual and buccal surfaces of tooth needs to be nearly vertical**   #### Composite Addition Adding composite above the retentive area is a method used when the lingual and buccal surfaces of the tooth are nearly vertical. Clinical photo showing a dental handpiece in use on a tooth during the 'Raising Height of Contour' procedure. The image demonstrates adding composite material above the retentive area. Diagram illustrating four stages of mouth preparation to demonstrate the requirement that 'Lingual and buccal surfaces of tooth needs to be nearly vertical'. The first and third panels show correct vertical alignment (green lines), while the second and fourth panels are marked with red 'X's indicating incorrect angulation. Mouth Preparation The University of Western Australia | Oral Health Centre of Western Australia 2nd stage **Raising Height of Contour** Surveyed crowns: - guiding planes, give adequate contour, rest seats    #### Surveyed Crowns Surveyed crowns are used to provide: - Guiding planes - Adequate contour - Rest seats Clinical procedure image showing a dental model with a green surveyor material on a prepared tooth. A metal instrument (likely a surveyor or matrix band) is being used to raise the height of contour. Clinical procedure image showing a dental model where a blue wax build-up has been placed on a tooth to demonstrate raising the height of contour for a crown preparation. Clinical procedure image showing a silver metallic crown form being fitted onto a prepared tooth in a dental model, demonstrating the final contour and fit. **Mouth Preparation** THE UNIVERSITY OF WESTERN AUSTRALIA | Oral Health Centre of Western Australia 2nd stage Raising Height of Contour     Raising Height of Contour Clinical photo showing a dental model with a grey metal crown preparation. The image illustrates the 'Raising Height of Contour' step in mouth preparation, as indicated by the OCR text. Clinical photo showing another view of a dental model with a grey metal crown preparation. This image also demonstrates the 'Raising Height of Contour' step in mouth preparation. Clinical photo showing a dental model with a silver metal partial denture framework and a tooth. This image is part of the 'Mouth Preparation' series from The University of Western Australia. Clinical photo showing a dental model with a pink gum-colored base and a white ceramic crown on a metal abutment. This image is part of the 'Mouth Preparation' series from The University of Western Australia. <script src="https://cdnjs.cloudflare.com/ajax/libs/html2pdf.js/0.10.1/html2pdf.bundle.min.js" referrerpolicy="no-referrer"></script> <script src="https://cdnjs.cloudflare.com/ajax/libs/html2pdf.js/0.10.1/html2pdf.bundle.min.js" referrerpolicy="no-referrer"></script> [^1]: Original PDF page 1: [[L8 Mouth Preparation for RPD.pdf#page=1|L8 Mouth Preparation for RPD, p.1]] [^2]: Original PDF page 2: [[L8 Mouth Preparation for RPD.pdf#page=2|L8 Mouth Preparation for RPD, p.2]] [^3]: Original PDF page 3: [[L8 Mouth Preparation for RPD.pdf#page=3|L8 Mouth Preparation for RPD, p.3]] [^4]: Original PDF page 4: [[L8 Mouth Preparation for RPD.pdf#page=4|L8 Mouth Preparation for RPD, p.4]] [^5]: Original PDF page 5: [[L8 Mouth Preparation for RPD.pdf#page=5|L8 Mouth Preparation for RPD, p.5]] [^6]: Original PDF page 6: [[L8 Mouth Preparation for RPD.pdf#page=6|L8 Mouth Preparation for RPD, p.6]] [^7]: 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