15.-SAS_DEN029_Lesson15.pdf

DEN 029: Dental Materials Lecture Student Activity Sheet #15 Name: ____________________________________________________________...

DEN 029: Dental Materials Lecture Student Activity Sheet #15 Name: ____________________________________________________________ Class number: _______ Section: ____________ Schedule: _____________________________________ Date: _______________ LESSON TITLE: Types and Uses of Dental Resins MATERIALS: Ballpens, erasers, pencils and LESSON OBJECTIVES: module At the end of the day, you will be able to: 1. Learn the uses of dental resins. REFERENCES: 2. Know the usefulness of dental resins in dental profession. Kenneth J. Anusavice – 3. Apply the knowledge you acquire in the lecture to your laboratory Phillips’ Science of Dental exercises. Materials (2012, Saunders) PRODUCTIVITY TIP: Good Day dear students. Let us be thankful for another day given to us, to live, to explore, to learn and feed our minds of useful topics that will help us become a Dentist soon… So, sit down and will start our minds working. Enjoy your day! A. LESSON PREVIEW / REVIEW Introduction (2 minutes) Good day my dear students. Welcome to DEN 029 (Dental Materials Lecture)! The topic is about Dental resins. Let us continue our learning in knowing the types and uses of resins in Dentistry. Let us continue to feed our minds and focus on our lesson. Enjoy and God bless! Activity 1: What I Know Chart, part 1 (3 minutes) What I Know Guide Questions: What I Learned (Activity 4) 1. How do you define Acrylic Resin 2. What are the properties of denture base resin? 3. What are the different uses of Dental resins? This document is the property of PHINMA EDUCATION  DEN 029: Dental Materials Lecture Student Activity Sheet #15 Name: ____________________________________________________________ Class number: _______ Section: ____________ Schedule: _____________________________________ Date: _______________ B. MAIN LESSON Activity 2: Content Notes (20 minutes) Types and Uses of Dental Resins:  Uses of Resin in Dentistry: - restoration of missing teeth - restoration of missing tooth structure like enamel, dentin and cementum - denture base – 95% of prostho plastics are acrylic type - filling material  Acrylic Plastics as Denture Bases    ACRYLIC RESIN - are derivatives of ethylene and contains vinyl group in their structural formula. - There are two acrylic resin series that are of dental interest.  Acrylic Acid  Methacrylic Acid  Acrylic are supplied in different forms, like:  powder-liquid – most popular form  Gels  Sheets or Blanks This document is the property of PHINMA EDUCATION  DEN 029: Dental Materials Lecture Student Activity Sheet #15 Name: ____________________________________________________________ Class number: _______ Section: ____________ Schedule: _____________________________________ Date: _______________  COMPOSITION:  POWDER – pre-polymerized powder described as small spheres called beads or pearls.  contains 1% benzoyl peroxide initiator  opacifier like titanium dioxide is present to make the material translucent This document is the property of PHINMA EDUCATION  DEN 029: Dental Materials Lecture Student Activity Sheet #15 Name: ____________________________________________________________ Class number: _______ Section: ____________ Schedule: _____________________________________ Date: _______________  inorganic pigment to attain specific denture base shade and stains can be added also during denture processing  dyed synthetic fibers are added to simulate minute blood vessels underlying the oral mucosa.  LIQUID  Methyl methacrylate monomer  Methyl ether of hydroquinone inhibitor, less than 0.1%  Dimethacrylate or cross-linking agent – resist crazing and improves their fatigue properties. o Organic amine – if chemically cured as accelerator o Plasticizers – Dibutyl phthalate and glycol ethyl phthalate. Butadiene- styrene rubber  Radiopacifier – 10-15% of bismuth or uranyl salts provides adequate radiodensity. o Its’ disadvantage is increase transverse deflection, water sorption and decreases handling qualities.  Properties of Denture Base Resin: - Low in strength - Fairly flexible - Brittle - Soft and reasonably high resistance to failure in fatigue (1.5 million flexures before failure at maximum stress of 17 Mpa) This document is the property of PHINMA EDUCATION  DEN 029: Dental Materials Lecture Student Activity Sheet #15 Name: ____________________________________________________________ Class number: _______ Section: ____________ Schedule: _____________________________________ Date: _______________ - Low thermal conductivity o Decrease thermal stimulation of underlying soft tissues o Relatively low heat distortion temperature of 95 0C - Volumetric polymerization shrinkage of 3:1 polymer:monomer ratio is high (6%). - Water sorption is also high (0.6 mg/cm2 or 2%) o There is expansion and may compensate polymerization shrinkage. - Adhesion of acrylic to metal and porcelain is poor, bonding can be achieve through mechanical retention. o 10-15% 4 META increases bonding between cross-linked teeth and metal. - Color is stable - Excessive residual monomer may cause toxicity or some form of soft tissue reaction.  Room temperature-processed or self-cured acrylic dentures: - More residual monomer is present - Residual monomer will initially serve as plasticizer - As this residual monomer be leached out the physical property will be improved - Residual monomer may cause tissue irritation - Room temperature processed is more accurate than heat cured, with dimensional change of less than 0.1%  Processing techniques for acrylic denture base: 1. DOUGH MOLDING TECHNIQUE 2. INJECTION MOLDING  Initiation of Polymerization 1. Heat 2. Chemicals 3. Microwave  INJECTION MOLDING: - Polymer-monomer mixture is processed under pressure - More accurate than the dough-compression molding technique - Requires a less highly trained technician This document is the property of PHINMA EDUCATION  DEN 029: Dental Materials Lecture Student Activity Sheet #15 Name: ____________________________________________________________ Class number: _______ Section: ____________ Schedule: _____________________________________ Date: _______________  Dough-compression molding technique  Most commonly used technique  Steps for heat processing acrylic:  1. The appropriate amount of liquid is poured into a mixing jar, the powder is added until the liquid is absorbed  Powder-liquid system o 3:1 ratio – minimizing shrinkage and temperature rise during processing  2. The top of the mixing jar is screwed on, and the material is allowed to stand while the solution of the powder and the liquid takes place.  During the SOLUTION PROCESS the material changes from a sandy, to a sticky, to a doughlike consistency. This document is the property of PHINMA EDUCATION  DEN 029: Dental Materials Lecture Student Activity Sheet #15 Name: ____________________________________________________________ Class number: _______ Section: ____________ Schedule: _____________________________________ Date: _______________  DOUGHLIKE CONSISTENCY o The material separates easily from the side of the mixing jar o Breaks cleanly with a snap when pulled apart rapidly o Ready to pack in the DENTURE MOLD contained in a denture flask. o Less than 40 minutes DENTURE MOLD o Constructed by use of a clinically acceptable waxed up denture in a stone cast This document is the property of PHINMA EDUCATION  DEN 029: Dental Materials Lecture Student Activity Sheet #15 Name: ____________________________________________________________ Class number: _______ Section: ____________ Schedule: _____________________________________ Date: _______________  The waxed up denture and the stone cast are invested in a split metal denture flask with gypsum products.  The flask is then immersed in boiling water for a few minutes to remove the wax  Liquid alginate separator is applied to all surfaces except those of the teeth. This document is the property of PHINMA EDUCATION  DEN 029: Dental Materials Lecture Student Activity Sheet #15 Name: ____________________________________________________________ Class number: _______ Section: ____________ Schedule: _____________________________________ Date: _______________  3. The acrylic dough is placed into the denture mold. An excess of the acrylic dough is placed into the part of the flask containing the teeth. A thin plastic sheet is placed over the acrylic and the flask is put together, and pressure is applied to force the dough into all portions of the mold and to eliminate excess.  4. The flask is opened and the excess is trimmed away.  TRIAL PACKING – the procedure is repeated several times until no excess appears; at this point the plastic separating sheet is removed and the flask is closed and placed in a clamp under pressure. This document is the property of PHINMA EDUCATION  DEN 029: Dental Materials Lecture Student Activity Sheet #15 Name: ____________________________________________________________ Class number: _______ Section: ____________ Schedule: _____________________________________ Date: _______________  5. The denture flask under pressure is placed in a heated polymerization bath, the most common one being a TEMPERATURE CONTROLLED WATER BATH at 73 degrees celcius for 8hours or longer (frequently overnight).  6. Flask is removed and allowed to cool to room temperature.  The denture is separated from the investment and cleaned.  The periphery of the denture is finished with a variety of instruments and only the non-tissue bearing surface are polished.  Polishing is done under WET CONDITIONS because temperatures sufficient to decompose and distort the acrylic plastic can result to dry polishing. This document is the property of PHINMA EDUCATION  DEN 029: Dental Materials Lecture Student Activity Sheet #15 Name: ____________________________________________________________ Class number: _______ Section: ____________ Schedule: _____________________________________ Date: _______________  7. The denture is then ready for delivery, adjustment of occlusion and any final adjustment by the dentist. REVIEW:  Heat-curing system is the most commonly used method of processing dentures despite the linear dimensional shrinkage is about 0.3% compared to that of chemically cured acrylics Activity 3: Skill-building Activities (10 mins + 2 mins checking) Answer the following questions: ________1. Are derivatives of ethylene and contains vinyl group in their structural formula. ________2. These are added to simulate minute blood vessels underlying the oral mucosa. ________3. Acrylic are supplied in different forms, like: ________4. ________5. ________6. It is present to make the material translucent. ________7. Give at least 3 properties of denture base resin: ________8. ________9. ________10. It is a procedure that is repeated several times until no excess appears. Activity 4: What I Know Chart, part 2 (2 minutes) Go back to the “What I Know Chart” in Activity 1 and answer the “What I Learned” column. This document is the property of PHINMA EDUCATION  DEN 029: Dental Materials Lecture Student Activity Sheet #15 Name: ____________________________________________________________ Class number: _______ Section: ____________ Schedule: _____________________________________ Date: _______________ Activity 5: Check for Understanding (5 minutes) Please answer the short quiz as honestly as you can. Let’s go! My Score: _____________ 1. Most commonly used technique for processing acrylic denture base : a. Injection molding technique b. Multiple Mix technique c. Reline technique d. Dough-compression molding technique 2. A synthetic polymer material made from an organic acid: a. Co-polymer b. Light activated c. Acrylic d. Initiator 3. The following are the properties of waxes: 1. Color is stable 2. High in strength 3. Soft and reasonably high resistance to failure in fatigue 4. Low thermal conductivity a. 1, 2 and 3 are correct b. 2, 3 and 4 are correct c. 1, 3 and 4 are correct d. All of the above 4. The following statement are true about Injection molding except: a. Most commonly used technique b. Polymer-monomer mixture is processed under pressure c. More accurate technique d. Requires a less highly trained technician 5. This is the first stage when the powder is wetted by the liquid and resembles wet sand at the beach: a. Sandy b. Stops c. Doughy d. Heat-activated Stop and check your answers against the Key to Corrections found at the end of this Activity Sheet. Write your score/s on your paper. This document is the property of PHINMA EDUCATION  DEN 029: Dental Materials Lecture Student Activity Sheet #15 Name: ____________________________________________________________ Class number: _______ Section: ____________ Schedule: _____________________________________ Date: _______________ C. LESSON WRAP-UP Activity 6: Thinking about Learning (5 minutes) A. Work Tracker You are done with this session! Let’s track your progress. Shade the session number you just completed. B. Think about your Learning: Please answer the following questions: 1) Please rate your activity today by placing a check mark (/) before a choice. Please explain your choice on the blank space beside the table: 1. Boring 2. Not informative 3. Challenging 4. Fair 5. Fun 2) “What details in the content and/or activities were not clear to you?” ________________________________________________________________________________________ ________________________________________________________________________________________ ________________________________________________________________________________________ ________________________________________________________________________________________ ________________________________________________________________________________________ ________________________________________________________________________________________ D. FREQUENTLY ASKED QUESTIONS: What is acrylic resin used for in dentistry? Acrylic resin is usually the material of choice for full denture bases and ‘gumwork’ for removable devices. It has also been the chemical model for many material developments in dentistry, such as restorative materials. This document is the property of PHINMA EDUCATION  DEN 029: Dental Materials Lecture Student Activity Sheet #15 Name: ____________________________________________________________ Class number: _______ Section: ____________ Schedule: _____________________________________ Date: _______________  What is the importance of benzoyl peroxide in acrylic resin? Benzoyl peroxide in acrylic resin is used to initiate free radical chain polymerization of the monomer, similar to the polystyrene synthesis.  How is acrylic resin made? Acrylic resins are synthesized from a wide selection of acrylic and methacrylic ester monomers and low level of monomers having other functional groups. Most of the commercial processes are free-radical- type additional reactions conducted at elevated temperature in the presence of an initiator. KEY TO CORRECTIONS: Activity 3: 1. Acrylic Resin 2. Dyed synthetic fibers 3. Powder-liquid 4. Gels 5. Sheets or blanks 6. Titanium dioxide 7. Color is stable 8. Low in strength, fairly flexible, brittle 9. Soft and reasonably high resistance to failure in fatigue 10. Trial Packing Activity 5 Short Quiz: 1. d 2. c 3. c 4. a 5. a Prepared by: AILEEN D. ATILLO, DMD Subject Instructor Southwestern University PHINMA - College of Dentistry This document is the property of PHINMA EDUCATION  DEN 029: Dental Materials Lecture Student Activity Sheet #15 Name: ____________________________________________________________ Class number: _______ Section: ____________ Schedule: _____________________________________ Date: _______________ This document is the property of PHINMA EDUCATION