DES410 Fixed & Removable Prosthodontics PDF Exam - European University Cyprus

DES410 School of Dentistry Fixed & Removable Prosthodontics Department of Dentistry Dr. C. Theocharides & Dr. A. Panayiotou Dr. Christos Theocharides...

DES410 School of Dentistry Fixed & Removable Prosthodontics Department of Dentistry Dr. C. Theocharides & Dr. A. Panayiotou Dr. Christos Theocharides Dr. Alexandros Panayiotou (BDS, BSc, MFDS RCSEd, MclinDent Pros, MPros RCSEd) (DDS, MD) Uk Registered Specialist In Prosthodontics BG Specialist in Prosthodontics  School of Dentistry EXAM FORMAT Ø 20MCQs – 10 fixed and 10 removable (each worth 1 mark) Ø In the MCQ Questions you will have 5 OPTIONS. In each questions there is only ONE CORRECT ANSWER Dr.– C. Ø 10 SAQs Theocharides 5 fixed & Dr. and 5 removable A.worth (each Panayiotou 4 marks) Ø The questions are mainly clinical based. It is advised to review all notes from year 3 as well as the clinical guidelines. Ø READ THE QUESTION CAREFULLY BEFORE YOU ANSWER  School of Dentistry Crowns Ø Indications for a dental crown: § Protection of the remaining tooth structure § Alteration of Aesthetics § Alteration of crown form to facilitate the construction of removable partial dentures (act as abutments) § To alter the occlusal plane Dr. C. Theocharides & Dr. A. Panayiotou Ø Most conservative to most destructive crowns: § Zirconia (monolithic) § All metal Crown § All Ceramic Crown § Ceramo-metal crown § Porcelain fused to zirconia  School of Dentistry Tooth reductions Biomaterials Reductions Occlusal (Posterior) Incisal (Anterior) Axial Least destructive Zirconia 1mm-1.5mm (at 1.5mm-2mm 0.5mm-1mm (monolithic) functional cusp) (can drop down to 0.3mm in some cases) All metal crown 1mm-1.5mm (at 1.5mm-2mm 0.5mm Dr. C. Theocharides & Dr. A. Panayiotou functional cusp) All Ceramic crown 1mm-1.5mm (at 1.5mm-2mm 1mm (e.g. Lithium functional cusp) disilicate emax) Ceramo-metal 1.2mm-2mm (at 1.5mm-2mm 1.2mm crown functional cusp) Porcelain fused to 1.5m-2mm (at 2mm-2.5mm 1.5-2mm Most destructive Zirconia (Lava functional cusp) Crowns) Maxillary teeth – Functional cusp is the palatal Mandibular Teeth – Function cusp is the buccal  School of Dentistry Crown preparation (steps) 1. Take shade of crown (if you will prepare for porcelain or zirconia) 2. Take two or three putty indices 3. Use local anaesthetic if required 4. Prepare the tooth appropriately (use indices as guides) Dr. C. Theocharides & Dr. A. Panayiotou 5. Construction of temporary crown 6. Placement of retraction cord with haemostatic agent 7. Take impression 8. Place temporary crown 9. Check occlusion and adjust if needed 10. Complete records and laboratory card  One stage Impression technique step by step procedure: Choose the appropriate tray Apply adhesive on tray and allow for it to dry (based on manufacturers recommendations) Make sure if there are any undercuts in the mouth that the material could engage they are appropriately blocked (wax can be used to block them). Dr. C. Theocharides & Dr. A. Panayiotou Ask your clinical assistant to load the heavy bodied material into the selected tray. The green/blue mixing tip should be used. At the same time syringe the wash material (light bodied) around the prepared tooth / teeth – the yellow mixing tip with the yellow intra-oral tip should be used Place the loaded tray into the mouth Hold the tray firmly until the impression has thoroughly set (Once set, should not be left for too long as it can lock in any undercuts) Remove the impression from mouth, rinse and disinfect to manufacturer’s recommendations.  School of Dentistry Inspection of the Quality of the Impression Dr. C. Theocharides & Dr. A. Panayiotou  School of Dentistry Crown cementation (steps) 1. Check your lab work – check fit of crown on die, check shade 2. Remove temporary restoration 3. Clean the underlying prepared tooth 4. Try in the restoration Dr. C. Theocharides 5. Check marginal & Dr. points fit (with probe), contact A. Panayiotou and occlusion 6. Check patient is happy with fit and appearance 7. Remove crown and clean both crown fit surface and fit surface of tooth. If indicated sandblast with Aluminium oxide 50µm 8. Cement with appropriate cement. Check and remove any excess cement. Also recheck occlusion  School of Dentistry Cements or Luting agents PERMANENT (HARD) CEMENTS SOFT (Temporary) CEMENTS (Zinc Oxide with /without - definitive cementation Eugenol) (Conventional cements) Dr.restorations - provisional C. Theocharides & Dr. A. Panayiotou - acid-base reaction (Resin cements) - definitive restorations if - polymerization reaction (Hybrid cements) a) tooth is symptomatic b) trial assessment is required - combination of above reactions  School of Dentistry Choosing the Right Cement (Luting or Bonding?) I. The restoration material The weaker the material, the stronger should be the cement. Cements that merely lute and do not bond, keep the applied forces concentrated at the tooth-restoration interface; bonded cements dissipate forces applied to the restoration away from the tooth-restoration interface. Dr. C. Theocharides & Dr. A. Panayiotou II. The amount of retention needed (preparation form, tapers, length of crown/ walls)  School of Dentistry Non-silicate ceramics, especially zirconia, have become a topic of great interest. A clinical problem with the use of zirconia-based components is the difficulty in achieving suitable adhesion with intended synthetic substrates or natural tissues. Traditional adhesive techniques used with silica-based ceramics Dr. C. Theocharides & Dr. A. Panayiotou do not work effectively with zirconia. Currently, several technologies are being utilized clinically to address this problem, and other approaches are under investigation. Most focus on surface modification of the inert surfaces of high strength ceramics. The ability to chemically functionalize the surface of zirconia appears to be critical in achieving adhesive bonding.  School of Dentistry Unfortunately, the composition and physical properties of ZrO2 differ from conventional silica-based materials like porcelain. Zirconia is not readily etched , and requires Dr. C. Theocharides & Dr. A. Panayiotou very aggressive mechanical abrasion methods to be used to increase surface roughness, possibly creating strength reducing surface flaws Resin cements and primers containing the acidic monomer 10- MDP- (methacryloyloxydecyl dihydrogen phosphate) are the recommended cements for zirconia ceramics as MDP can chemically bond with zirconia. Examples of such cements and primers are Panavia V5, SE Bond, SA Luting Cement (Kuraray, Osaka, Japan) Dr.newer and the C. Theocharides & Dr. adhesive Scotchbond Universal A. Panayiotou (3 M Espe, Germany). Aside from these 10 MDP-containing primers, primers such as Metal/Zirconia Primer (Ivoclar), Z-Primer (Bisco), and AZ Primer (Shofu) which contain phosphoric acid monomers can also be used to promote the adhesion of alumina and zirconia due to chemical bond formation.  Some tips Avoid any contact of phosphoric acid with the zirconia restoration during the cementation process. The phosphate ion Researches has shown more debonding of zirconia in the acid greatly reduces any potential bonding to the restorations cemented with resin cements than those zirconia. cemented with RMGI cements, despite their being stronger than RMGI cements. To reduce the debonding Do not clean the tooth preparations with prophy paste. The problem with resin cements, researches has shown that emollients and fluoride in some prophy pastes can be negative placement of a bonding agent on the tooth preparation and cause crowns to come off. Use flour of pumice and water. and on the internal side of the zirconia restoration before Dr. C. Theocharides & Dr. A. Panayiotou cementing with self-adhesive or adhesive cements significantly increases their bond to tooth structure. The unfortunate situation relative to cementing procedures for zirconia restorations is that there is no agreement among Use resin-modified glass ionomer (RMGI) cement for zirconia manufacturers of cements as to the best technique. restorations when the tooth preparations have near-optimum characteristics. Most clinicians and researchers would agree that the tooth preparation should be at least 4 mm in height from the gingival margin to the occlusal table, and that the lack of parallelism of the preparation walls should be up to, but not more than, 20 degrees from the long axis of the tooth being prepared.  School of Dentistry Cement Type Recommended for Primary Strength Primary Weakness Recommended for cast restorations on Lack of chemical adhesion. Permanent Cements normal, conservatively prepared teeth. Zinc Phosphate Long clinical experience. Low tensile strength Mainly for cast restorations on retentive preparations when minimal pulp irritation is important (eg. In patients Relative biocompatibility. Mixing can be tricky as sensitive to with large pulp chambers). powder-to-liquid ratio. Polycarboxylate Dr. C. Theocharides & Dr. A. Panayiotou Cast metal and monolithic zirconia restorations mainly for posterior teeth. Adheres to enamel and dentine and exhibits good During setting is susceptible to moisture contamination – Glass Ionomer biocompatibility. Releases marginal solubility. Fluoride. Resin Modified GIC Similarly to GIC but when we seek a Less susceptible to early moisture Swelling or linear expansion. stronger luting cement. exposure than GIC. High strength similar to Resin luting cements Indicated for all-ceramic and laboratory- High retention strength values, Highly technique sensitive. processed composite restorations. Aesthetics Resin based Potential for post-operative sensitivity.  School of Dentistry Dr. C. Theocharides & Dr. A. Panayiotou Ø Articulating papers are used to check occlusal contacts. In crowns they are used to check if the provisional and definitive crowns are harmonious with the remaining occlusal contacts. Ø Normal Articulating paper can be 70-200 microns – Thick and mainly used for dentures Ø GHM articulating paper – 12-20 microns – Ideal to check occlusal contacts – most frequently used in restorative dentistry Ø Shimstock – 8 microns – also used in crowns and implant crowns.  School of Dentistry Treatment planning process Emergency Phase Investigation / Stabilisation Phase Dr. C. Theocharides & Dr. A. Panayiotou Rehabilitation Phase Maintenance & Monitoring Phase  School of Dentistry Clinical Case scenario: A patient comes to you complaining of acute pain from his tooth number 46. On examination you diagnose 46 with irreversible pulpitis due to extensive caries. Furthermore, you realise that there are several more carious cavities and there is advanced periodontal disease. Dr. C. Theocharides & Dr. A. Panayiotou How would you manage?  School of Dentistry Emergency phase: Acute pain on 46 – Either initiate RCT or extract if tooth is not considered unrestorable. You do not need to complete the RCT especially if there are several carious cavities and active periodontal disease Stabilisation phase: Restore / temporise carious cavities Stabilise periodontal disease Dr. C. Theocharides & Dr. A. Panayiotou Complete RCT on 46 Rehabilitation phase: Focus on the prosthetic stage. Crown 46. Focus on restoring all the teeth that need to be restored Maintenance: Set the recall intervals for check-ups and Hygiene  School of Dentistry Common Errors affecting Marginal Fit and failing to seat the crown Ø Tight Proximal contacts Ø Casting blebs on fit surface Ø Over / Under – crown extended margins Ø No dieDr. spacer C. Theocharides & Dr. A. Panayiotou Ø Impression distortion The first four may be correctible, but a casting made from a distorted impression will need to be remade from a new impression  School of Dentistry Checking the fit of the crown Visual: ü Margins ü Direct or with mirror ü Magnification Dr. C. Theocharides & Dr. A. Panayiotou Using instruments: ü Use explorer (Straight probe) – esp. if margins are subgingival ü Use the correct size tip and angle of approach  School of Dentistry Types of Defective margins Over-extended margin Under-extended margin Over-Contoured Open Margin (A) (B) (thick) (C) (D) § Poor Impression § Poor impression § Over-waxed § Casting not completely § Surplus untrimmed wax § Over-polished casting seated or ceramic § Improperly trimmed die § Poor impressions § Improperly trimmed die § Difficulty identifying finish § Incomplete casting line § Improperly trimmed die Dr. C. Theocharides & Dr. A. Panayiotou § Over-polished casting  School of Dentistry Evaluating the crown prior to cementation Check fit of the crown on the die prior to assessing it in the patients mouth I. Proximal Contacts – use floss to check II. Marginal Fit – use an explorer to check III. Dr. C. Theocharides Aesthetics & Dr.andA.shade – Check both shape Panayiotou IV. Occlusion – Check using GHM articulating paper The order is important as if the proximal contacts are too tight then it will be impossible to assess the rest.  School of Dentistry Semi-precision attachments Dr. C. Theocharides & Dr. A. Panayiotou  School of Dentistry Objectives of Modifying Abutment tooth contours (Advantages of milled crowns) Ø Develop an acceptable path of insertion Ø Promote favourable biomechanical properties (Retention, support and stability) Ø Improve aesthetics Dr. C. Theocharides & Dr. A. Panayiotou Ø Improve the structural durability of a tooth, especially if heavily restored  Options for replacing teeth Acrylic Partial Cobalt Chrome Removable: Valplast (flexible) Complete Acrylic Cobalt Chrome (not so common) Dr. C. Theocharides & Dr. A. Panayiotou Resin-bonded bridge (minimally invasive) Fixed: Implant (ideal but cost implications) Conventional bridge (invasive)  Factors affecting Prognosis of Teeth Patient Factors: The patient's restorative status (endodontic, periodontal, and structural integrity), medical, dental and social factors, expectations, financial status, and behaviour, must all be carefully evaluated in the decision-making process Dr. C. Theocharides & Dr. A. Panayiotou (Dawood & Patel, 2017) Dentist Factors: Skills sets, Post-graduate training, years of experience and available equipment and materials will also affect the decision making to keep or remove a tooth.  Prognosis Structural Integrity: Ø There needs to be at least more than 1.5mm of ferrule in order to have enough structure to support a fixed prosthesis Ø Dentin thickness needs to be >1mm especially in Root Treated teeth Dr. C. Theocharides & Dr. A. Panayiotou Endodontic Integrity: Ø A predictable endodontic outcome necessitates the presence of either a healthy pulp or an acceptably cleansed and obturated root canal area Ø We know that the key to success of a root canal treatment is the success of the coronal seal (Ng et al. 2008) Periodontal Integrity: Ø The larger the amount of bone loss and the greater the mobility the lower the tooth prognosis.  The Strategic Value of a tooth Aesthetic Impact Medical Impact Dr. C. Theocharides & Dr. A. Panayiotou Occlusal Impact Prosthodontic Impact Functional Impact Financial Impact  School of Dentistry What is RCP? Definition of CR: A bilateral, unstrained position of the mandible in which the condylar disc assembly is in the most superior anterior position in the glenoid fossa and the initial 20 mm of incisal opening is a pure hinge axis. RCP is when there is the initial tooth to tooth contact in CR. Dr. reproducible RCP is the only C. Theocharides position & of Dr. the A. Panayiotou occlusion so is used when we want to make large changes to the occlusion (eg. restoring multiple units) in the fully dentate individual. To alter the occlusion in this way is called Re-organised approach and is used in wear cases or when restoring multiple units. RCP is also used when dealing with edentulous patients (making complete dentures)  School of Dentistry What is ICP? Definition: This is the position where there is most tooth to tooth contact for that individual's occlusion. We can also use ICP the intercuspal position, when we conform to the patients’ occlusion. This is what you are doing every time you place a restoration, you ensure that Dr. C. Theocharides & Dr. A. Panayiotou the restoration harmonises with the occlusal scheme. This is the Conformative approach. For the majority of your clinical work as a General Dental Practitioner you will use the conformative approach. For example: Placement of a crown or bridge.  School of Dentistry Management of teeth with extensive Dr. C. Theocharides & Dr. A. Panayiotou tooth loss  School of Dentistry Toothwear What would you check in a clinical examination? § Presenting complaint § Medical History § Social History § Diet History Dr. C. Theocharides & Dr. A. Panayiotou § Extra-oral examination (What is important?) § Intra-oral examination o Identify the lesions present to determine type of wear o Sensibility tests o Radiographs o Prosthodontic assessment  School of Dentistry Types of Tooth Surface Loss Ø Attrition Ø Abrasion Ø Erosion / Acid dissolution Ø Dr. C. Theocharides & Dr. A. Panayiotou Abfraction Ø Caries Ø Iatrogenic Ø Trauma  School of Dentistry Toothwear How do you manage such cases: What type of wear is it? Would you treat attrition the same way as erosion? Monitor ? / Treat ? If you are planning on restoring the original shape of the teeth how would you plan it? Dr. C. Theocharides & Dr. A. Panayiotou Articulated study casts Wax-ups What materials can be used to restore this teeth? When would you offer a splint? What types of splints? What does a hard splint do? What does a soft splint do?  School of Dentistry Clinical Features Attrition Erosion Flat cusps, matching wear facets, excessive Teeth lose surface characteristics fracture of restorations, hypersensitivity, Enamel is smooth & shiny fremitus Dentine often looks very shiny Tooth surface loss not involved in ‘Cupping’ seen articulation Old amalgams ‘proud’ or Dr. C. Theocharides Masseteric hypertrophy & tenderness & Dr. A. ‘outstanding’ Panayiotou Prominent antagonial notching Pterygoid tenderness TMJ – clicking, crepitus, trismus, limitation of mandibular movement Tongue scalloping, cheek ridging  School of Dentistry Management of TSL Active monitoring Most conservative Splint Therapy Composite Build-ups Onlay Dr. C.Dentures Theocharides & Dr. A. Panayiotou Crown and Bridges Crowns with Dentures Overdentures Dentures Least (Extractions)) Implants  How can you manage a patient suffering with TSL from erosion? Dr. C. Theocharides & Dr. A. Panayiotou (most conservative to most destructive)  How can you manage a patient suffering with TSL from erosion? Carry out a diet analysis and suggest changes Most conservative Recommend use of fluoride containing toothpasteDr. C. Theocharides indicated for repair and & Dr. A. Panayiotou protection of teeth Restore function and aesthetics using composite resin restorations Least (Extractions)) Plan to restore the warn down teeth using indirect lab made restorations Note: Splints should not be offered in patients with active erosion ability compensation - - School of Dentistry How a wear case is managed? a b Take Articulated study casts in CR c d Wax-ups made - Dr. C. Theocharides & Dr. A. Panayiotou Demonstrate to patient e f - Putty index or plastic retainer made - g h Composite used to restore the 4 - upper anterior teeth - - j i Fig. 2 Clinical case 1. a) Pre-operative BDJ Mehta Toothwear Case view. b-c) Study casts. d-e) Diagnostic wax up to conform to occlusal and aesthetic prescription. f-g) Silicone index (Optosil P  Role of Splints Ø To test increase in occlusal vertical dimension. Ø To check patient is in RCP. Ø To treat TMD patients where the pain is of muscle origin. Dr. C. Theocharides & Dr. A. Panayiotou Ø To prevent toothwear before and after restorative care. Ø To check patients can wear partial dentures or overdentures or onlay dentures Dr. C. Theocharides & Dr. A. Panayiotou Posts & Cores Post: The post (dowel) is a metal or other rigid restorative material placed in the radicular(root) portion of a non vital tooth. A dowel traditionally made of metal is fitted in to a prepared canal of a natural tooth. Core: Refers to substructure, which replaces missing coronal structure and retains the final restoration. Dr. C. Theocharides & Dr. A. Panayiotou Dental posts should be recognized as simply a way to help to anchor a dental core in a tooth. If enough natural tooth structure exists that it can be relied upon to securely hold and retain the core, then no post is needed  How to decide which post is the ideal: Direct / Indirect (TIP) It all comes down to the amount of ferrule present! The absolute minimum is 1.5mm Ø 2-3mm ferrule (height) you are better off with an Ferrule indirect cast post. Dr.you Ø ≥ 3-4mm ferrule C. can Theocharides & post then use a direct Dr. A. Panayiotou Ø For molar teeth its best to consider a Nayyar core instead of a post and core How much apical GP do we always leave? (The minimum) 44 Be able to differentiate between the indirect and the direct method. Indirect: Post and core fabricated in the laboratory (Usually involves the cast post) Direct: Post and core fabricated chairside (Usually involves fibre composite post and bulk filled composite for the core) Dr. C. Theocharides & Dr. A. Panayiotou The is also the direct / indirect method where duralay (ideally) or wax is used to make an exact representation of the post and core system and this is send to the laboratory which is then made into a cast post and core. Questions: WHAT IS THE IDEAL LENGTH OF A POST?  School of Dentistry Tooth Restorability Index A tooth restorability index (TRI) was developed to provide a structured assessment using defined parameters to evaluate remaining coronal tissue (remaining dentine for retention and resistance). Ø Tooth is decided into 6 equal sextants: 2 proximal, 2 buccal and 2 lingual Dr. C. Theocharides & Dr. A. Panayiotou Ø The TRI allowed scores of 0 to 3 in each tooth sextant, with a maximum score of 18 per tooth  School of Dentistry Tooth Restorability Index 0 – ‘None’ Throughout 2/3 or more of the tooth sextant there is no axial wall of dentine, or any dentine above the finishing line is so lacking in height as to be unable to contribute to retention and resistance of a core or crown. 1- Inadequate Coronal dentine present in the tooth sextant but, in terms of thickness, height or distribution Dr. clinical is, in the operators C. Theocharides &toDr. opinion, insufficient A.any make Panayiotou predictable contribution to retention and resistance. Dentine walls that are less than 1.5mm thick or more than twice as high as their thinnest part would be included in this category. 2 – Questionable More dentine is present that in 1, but in one’s clinical opinion it is not possible to be confident whether or not it will make a predictable contribution to retention and resistance. 3- Adequate There is sufficient coronal dentine in terms of thickness, height and distribution for the operator to feel confident that this sextant will contribute fully to retention and resistance of the core and final restoration.  School of Dentistry Tooth Restorability Index Dr. C. Theocharides & Dr. A. Panayiotou TRI was developed to assist the clinician with assessing the restorability of a tooth. Although this index was developed for root-treated teeth, it is also intended for assessment of vital teeth. Disadvantage: Subjective to clinician’s opinion of assessing each sextant.  School of Dentistry Make sure you read all the lectures and lab sessions as well as the clinical guidelines Do not only focus your revision on this Revision lecture but use it as a guide to pay some further attention on some topics. Dr. C. Theocharides & Dr. A. Panayiotou ANY QUESTIONS? GOOD LUCK!