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AT C Quiz #5 (Math)
Quiz by Michael Chan
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Sumulat ng quiz gamit ang mga sumusunod na tanong: 1. Alin sa sumusunod na kalagayan ang nagpapakita ng lubos na pagtulong ng pamahalaan sa mga mamamayan? A. Pagbibigay ng buwis sa pamahalaan B. Pagbibigay pautang para sa mga magsasaka C. Pagpapawalang-bisa sa pagkakakulong dahil sa utang D. Pagbigay galang sa mga matataas na opisyal ng pamahalaan 2. Ano ang itinuring pinakamahalagang naidulot ng pakikipagkalakalan sa Kabihasnang Greek? A. Lumago ang mga negosyanteng Greek. B. Nakapipili ang mga mamamayan ng iba’t ibang produkto. C. Nakapaglalakbay ang mga mamamayang Greek sa ibang lupain. D. Nalalaman nila ang mga bagong ideya at teknik mula sa ibang lugar. 3. Sa lungsod-estado ng Sparta, ang mga batang lalaking malulusog ay sinanay na sa mga serbisyong militar. Ano ang iyong mahinuha sa kalagayang ito? A. Pinahalagahan ang kanilang edukasyon. B. Pinahalagahan ang kalinisan ng kampo-militar C. Pinahalagahan ang kanilang sandatahang lakas. D. Pinahalagahan ang karapatan ng mga kababaihan at kalalakihan. 4. Ano ang kahulugan ng salitang tyrant sa kasalukuyan? A. masipag na lider B. masayahing lider C. malupit na pinuno D. makupad na pinuno 5. Dahil sa pagsalakay at pagsakop nito sa mga Minoan, anong pangkat ng tao ang nagpayaman sa kabihasnang Greece? A. Athenian C. Mycenaean B. Minoan D. Spartan 6. Ano ang ginawa ng mga Minoan upang umunlad ang kanilang kabihasnan? A. pinalawig ang pagmimina sa lugar B. nagtatag ng mga arena upang kumita C. nakikipagkalakalan sa mga karatig lugar D. nakipaglaban at umangkin ng iba pang lupain 7. Ayon kay Pericles ng Athens, ang konstitusyon ng Athens ay isang demokrasya sapagkat nasa kamay ito ng nakakarami. Ano ang ipahiwatig ni Pericles? A. Ang pamahalaan ay hawak ng mga iilang mamamayan sa lipunan. B. Hari at reyna lamang ang may lubos na kapangyarihan sa kanilang bayan. C. Tanging opisyal ng pamahalaan lamang ang magdesisyon para sa kanilang bayan. D. Ang taong-bayan ang siyang magdesisyon kung sino ang dapat mamuno sa kanilang pamahalaan. 8. Ano ang pinakamahalagang natutunan ng mga Greek mula sa mga Phoenician? A. paggamit ng mga aklat B. paggamit ng lapis at papel C. pagtatag ng mga paaralan D. paggamit ng kanilang alpabeto 9. Anong pangyayari ang sanhi ng pagbagsak ng Mycenae? A. Pagsakop ng mga Dorian B. Pakikipagkalakalan sa ibang lugar C. Pagkasira ng kanilang mga pananim D. Epidemya at maraming tao ang namatay 10. Ano ang pinakamahalagaahang naiambag ng Athens sa kabihasnan ng daigdig? A. Asembleya C. Demokrasya B. Batas Militar D. Lungsod-Estado 11. Saan itinatag ang kabihasnang Minoan? A. Athens C. Parthenon B. Crete D. Sparta 12. Bakit mahalaga ang pagkakaroon ng mahusay at matibay na sandatahang-lakas sa isang bansa? A. para mapanatili ang kapayapaan at kaunlaran ng ibang bansa B. upang maipagtanggol ang sariling bansa laban sa mga kalaban C. upang maipakita sa buong mundo ang kahusayan at kagalingan D. para siguradong matatakot ang lipunan at susunod sa pamahalaan 13. Alin sa sumusunod ang hindi kabilang sa tinatamasa ng lehitimong mamamayan ng Greece? A. karapatang bomoto B. magkaroon ng ari-arian C. bibigyan ng porsiyento sa kalakalan D. humawak ng posisyon sa pamahalaan 14. Anong lungsod-estado ng Greece ang binansagang “pamayanan ng mga mandirigma”? A. Athens C. Mycenae B. Corinth D. Sparta 15. Anong lugar ang sentro ng pulitika at relihiyon ng Greece? A. Acropolis C. Arena B. Agora D. Polis
Gumawa ng quiz gamit ang mismong mga tanong: 1. Alin sa sumusunod na kalagayan ang nagpapakita ng lubos na pagtulong ng pamahalaan sa mga mamamayan? A. Pagbibigay ng buwis sa pamahalaan B. Pagbibigay pautang para sa mga magsasaka C. Pagpapawalang-bisa sa pagkakakulong dahil sa utang D. Pagbigay galang sa mga matataas na opisyal ng pamahalaan 2. Ano ang itinuring pinakamahalagang naidulot ng pakikipagkalakalan sa Kabihasnang Greek? A. Lumago ang mga negosyanteng Greek. B. Nakapipili ang mga mamamayan ng iba’t ibang produkto. C. Nakapaglalakbay ang mga mamamayang Greek sa ibang lupain. D. Nalalaman nila ang mga bagong ideya at teknik mula sa ibang lugar. 3. Sa lungsod-estado ng Sparta, ang mga batang lalaking malulusog ay sinanay na sa mga serbisyong militar. Ano ang iyong mahinuha sa kalagayang ito? A. Pinahalagahan ang kanilang edukasyon. B. Pinahalagahan ang kalinisan ng kampo-militar C. Pinahalagahan ang kanilang sandatahang lakas. D. Pinahalagahan ang karapatan ng mga kababaihan at kalalakihan. 4. Ano ang kahulugan ng salitang tyrant sa kasalukuyan? A. masipag na lider B. masayahing lider C. malupit na pinuno D. makupad na pinuno 5. Dahil sa pagsalakay at pagsakop nito sa mga Minoan, anong pangkat ng tao ang nagpayaman sa kabihasnang Greece? A. Athenian C. Mycenaean B. Minoan D. Spartan 6. Ano ang ginawa ng mga Minoan upang umunlad ang kanilang kabihasnan? A. pinalawig ang pagmimina sa lugar B. nagtatag ng mga arena upang kumita C. nakikipagkalakalan sa mga karatig lugar D. nakipaglaban at umangkin ng iba pang lupain 7. Ayon kay Pericles ng Athens, ang konstitusyon ng Athens ay isang demokrasya sapagkat nasa kamay ito ng nakakarami. Ano ang ipahiwatig ni Pericles? A. Ang pamahalaan ay hawak ng mga iilang mamamayan sa lipunan. B. Hari at reyna lamang ang may lubos na kapangyarihan sa kanilang bayan. C. Tanging opisyal ng pamahalaan lamang ang magdesisyon para sa kanilang bayan. D. Ang taong-bayan ang siyang magdesisyon kung sino ang dapat mamuno sa kanilang pamahalaan. 8. Ano ang pinakamahalagang natutunan ng mga Greek mula sa mga Phoenician? A. paggamit ng mga aklat B. paggamit ng lapis at papel C. pagtatag ng mga paaralan D. paggamit ng kanilang alpabeto 9. Anong pangyayari ang sanhi ng pagbagsak ng Mycenae? A. Pagsakop ng mga Dorian B. Pakikipagkalakalan sa ibang lugar C. Pagkasira ng kanilang mga pananim D. Epidemya at maraming tao ang namatay 10. Ano ang pinakamahalagaahang naiambag ng Athens sa kabihasnan ng daigdig? A. Asembleya C. Demokrasya B. Batas Militar D. Lungsod-Estado 11. Saan itinatag ang kabihasnang Minoan? A. Athens C. Parthenon B. Crete D. Sparta 12. Bakit mahalaga ang pagkakaroon ng mahusay at matibay na sandatahang-lakas sa isang bansa? A. para mapanatili ang kapayapaan at kaunlaran ng ibang bansa B. upang maipagtanggol ang sariling bansa laban sa mga kalaban C. upang maipakita sa buong mundo ang kahusayan at kagalingan D. para siguradong matatakot ang lipunan at susunod sa pamahalaan 13. Alin sa sumusunod ang hindi kabilang sa tinatamasa ng lehitimong mamamayan ng Greece? A. karapatang bomoto B. magkaroon ng ari-arian C. bibigyan ng porsiyento sa kalakalan D. humawak ng posisyon sa pamahalaan 14. Anong lungsod-estado ng Greece ang binansagang “pamayanan ng mga mandirigma”? A. Athens C. Mycenae B. Corinth D. Sparta 15. Anong lugar ang sentro ng pulitika at relihiyon ng Greece? A. Acropolis C. Arena B. Agora D. Polis
*MCQ Quiz: Understanding Good Practices in Writing AI Prompts** 1. **Q:** What is the first step in crafting an effective AI prompt? - a) Define the objective - b) Select the AI tool - c) Provide examples - d) Choose the target audience 2. **Q:** Why is it important to specify the target audience in a prompt? - a) It helps in choosing the right AI tool. - b) It ensures the output is tailored to the right level. - c) It determines the length of the prompt. - d) It makes the prompt more creative. 3. **Q:** Which of the following is a good practice when writing a prompt? - a) Keep the prompt vague to allow AI flexibility. - b) Include clear and specific instructions. - c) Write a very long and detailed prompt. - d) Start with examples before stating the objective. 4. **Q:** What is the role of examples in a well-structured prompt? - a) To confuse the AI with multiple possibilities. - b) To provide context and clarify expectations. - c) To make the prompt longer. - d) To show off knowledge of the subject. 5. **Q:** When should you select the AI tool in the prompt-writing process? - a) After defining the objective and specifying the audience. - b) Before defining the objective. - c) At the very end. - d) Before writing anything else. 6. **Q:** What is a common mistake to avoid when writing prompts? - a) Being too specific in instructions. - b) Including irrelevant information. - c) Mentioning the target audience. - d) Defining the objective clearly. 7. **Q:** How should the tone of a prompt be set? - a) It should be casual and open-ended. - b) It should be formal and precise. - c) It should change depending on the day. - d) It should be vague to encourage creativity. 8. **Q:** What is the final step in crafting a well-structured prompt? - a) Review and refine the prompt. - b) Select the target audience. - c) Provide examples. - d) Choose the AI tool. https://www.revisely.com/quiz/oEkao
Time-Telling Quiz: Half Past the Hour Name: ______________________ Date: ______________ What does "half past" specifically mean on an analog clock? A) 15 minutes have passed B) 30 minutes have passed C) 45 minutes have passed D) The hour has just begun When the minute hand points to 6, what position represents "half past"? A) The start of the hour B) Exactly halfway through the hour C) The end of the hour D) A quarter of the way through the hour If the hour hand is between 4 and 5, and the minute hand is on 6, what time is it? A) 4:15 B) 4:45 C) 4:30 D) 5:00 Which statement best describes how the hour hand moves? A) It moves quickly between numbers B) It moves slowly between numbers C) It stays in one place all the time D) It moves only at the top of each hour How many minutes are in a complete circle on a clock? A) 12 minutes B) 24 minutes C) 60 minutes D) 30 minutes When reading an analog clock for "half past", which hand should you look at first? A) The hour hand B) The second hand C) The minute hand D) The decorative hand What is the most important position of the minute hand when identifying "half past"? A) Pointing to 3 B) Pointing to 12 C) Pointing to 6 D) Pointing to 9 If a clock shows half past 7, how would this be written numerically? A) 7:15 B) 7:45 C) 7:30 D) 8:00 Which of the following is TRUE about clock hands? A) The shorter hand always shows minutes B) The longer hand always shows hours C) The longer hand shows minutes, the shorter hand shows hours D) Both hands move at exactly the same speed What is the primary challenge when learning to read "half past" times? A) Remembering the minute hand must be on 6 B) Counting all the numbers on the clock C) Understanding what an hour is D) Knowing the difference between AM and PM Answer Key: B B C B C C C C C A
Gumawa ng quiz gamit mismo ang mga sumusunod: 1. Saang kontinente matatagpuan ang Imperyong Romano? A. Amerika C. Asya B. Aprika D. Europa 2. Anong uri ng pamahalaan ang ipinalit ng mga Romano mula sa pagiging monarkiya? A. Aristokrasya C. Diktadurya B. Demokrasya D. Republika 3. Ano ang tawag sa mamamayang Romano na kasapi sa mayayamang asendero? A. Haciendero C. Patrician B. Negosyante D. Plebeian 4. Ang karaniwang mamamayang Romano o masa ay tinatawag na? A. Haciendero C. Patrician B. Negosyante D. Plebeian 5. Ano ang sinaunang kabisera ng bansang Italya? A. Roma C. Milan B. Florence D. Venice 6. Ilang Digmaang Punic ang naganap laban sa kapangyarihan ng Roma at Carthage? A. isa C. tatlo B. dalawa D. apat 7. Anong pangkat ang nagtatag ng Carthage na naging kalaban ng mga Romano? A. Assyrian C. Phoenician B. Lydian D. Sumerian 8. Ano ang pinakamagandang naidulot ng pagkakaroon ng Pax Romana? A. paghatid ng kasaganaan sa lipunan B. pagkaroon ng maraming tagapagtanggol C. pagpahalaga ng kapayapaan sa lipunan D. pag-unlad ng pangkabuhayan ng mga mamamayan 9. Alin sa sumusunod ang hindi salik sa pagbagsak ng Imperyong Romano? A. hindi matatag na pamumuno B. paglusob ng mga tribong barbaro C. may sariling paraan ang bawat isa D. pagkawala ng katuturan ng pagkamamamayan
RPMS Quiz: Quality vs. Efficiency 1. A teacher spends five hours creating a highly interactive digital game for a single 40-minute lesson. This is an example of prioritizing: • A) Quality over Efficiency • B) Efficiency over Quality • C) Administrative Competence • D) Resource Management • Hint: The focus is on high-level engagement, but the time investment is very high. 2. Which of the following best describes "Efficiency" in the context of the RPMS? • A) Submitting all MOVs and reports on or before the deadline with minimal errors. • B) Ensuring 100% of students pass the quarterly examination. • C) Creating the most aesthetically pleasing portfolio in the department. • D) Conducting home visits for every single student in a class of 50. • Hint: Look for the option that emphasizes timeliness and resource use. 3. Using a "template" or a "reusable slide deck" for lesson planning is a strategy to improve: • A) Efficiency • B) Instructional Diversity • C) Subject Matter Mastery • D) Classroom Discipline • Hint: Templates reduce the time spent on repetitive formatting. 4. If a teacher provides detailed, personalized feedback to every student but submits the grades two weeks late, they have achieved: • A) High Quality, Low Efficiency • B) Low Quality, High Efficiency • C) High Quality, High Efficiency • D) Low Quality, Low Efficiency • Hint: The work itself is excellent, but the timing is poor. 5. Which tool improves Efficiency without sacrificing the Quality of assessment data? • A) Automated Google Forms for multiple-choice quizzes. • B) Giving everyone a passing grade to save time on checking. • C) Writing long paragraphs of feedback on 200 paper-based essays. • D) Skipping assessments entirely to finish the syllabus faster. • Hint: Look for a balance where technology handles the "busy work." 6. When discussing Quality in your RPMS portfolio, which "Means of Verification" (MOV) is most appropriate? • A) Sample of student work with constructive teacher comments. • B) A logbook showing you arrived at school at 7:00 AM daily. • C) A certificate for attending a 1-hour webinar. • D) A photo of your organized teacher's cabinet. • Hint: Quality is evidenced by the impact on student learning. 7. The concept of "Doing the right things" (Effectiveness) represents: • A) Quality • B) Efficiency • C) Speed • D) Compliance • Hint: "Doing the right things" is about results; "Doing things right" is about process. 8. How does "Efficiency" help a teacher maintain "Quality" in the long run? • A) It prevents burnout by optimizing workload, leaving energy for creative teaching. • B) It allows the teacher to take more side jobs. • C) It ensures the teacher never has to talk to parents. • D) It proves that the teacher is smarter than their peers. • Hint: Consider the relationship between teacher well-being and performance. 9. If a teacher's RPMS rating for Quality is 5 (Outstanding) but Efficiency is 2 (Fair), what is the most likely reason? • A) The teacher produces excellent work but often misses deadlines. • B) The teacher is very fast but makes many mistakes in their reports. • C) The teacher is both slow and produces poor results. • D) The students are failing despite the teacher being very organized. • Hint: Check the gap between the high-standard output and the slow delivery. 10. What is the ultimate goal of balancing Quality and Efficiency in the PPST-RPMS? • A) To achieve sustainable professional excellence that benefits the learners. • B) To get a higher salary increase only. • C) To impress the School Head during the observation. • D) To finish the school year with the least amount of work possible. • Hint: It's about long-term growth for both teacher and student. ________________________________________ Answer Key: 1. A | 2. A | 3. A | 4. A | 5. A | 6. A | 7. A | 8. A | 9. A | 10. A ________________________________________
I'm wanting to make a vocab quiz using the following 1. Supply chain a) The sequence of activities involved in the production and distribution of a product (Correct) b) The sequence of activities involved in marketing a product (Incorrect - refers to a different aspect of business operations) c) The sequence of activities involved in hiring employees (Incorrect - unrelated to product production) d) The sequence of activities involved in customer service (Incorrect - unrelated to product production) 2. Intermediaries a) Middlemen or brokers who facilitate transactions between two parties (Correct) b) The final consumers of a product (Incorrect - refers to end-users, not intermediaries) c) The employees working at a company's headquarters (Incorrect - unrelated to transaction facilitation) d) The shareholders of a company (Incorrect - unrelated to transaction facilitation) 3. Specialization a) Focusing on a specific task or aspect of production to achieve expertise and efficiency (Correct) b) Expanding business operations to new markets (Incorrect - refers to a different concept) c) Maximizing profits through cost-cutting measures (Incorrect - unrelated to specialization) d) The process of developing new products (Incorrect - unrelated to specialization) 4. Coordination a) Organizing and harmonizing different elements or activities to work together effectively and efficiently (Correct) b) Maintaining independence and autonomy among different departments (Incorrect - opposite meaning of coordination) c) Creating a hierarchical structure within an organization (Incorrect - unrelated to coordination) d) Maximizing competition among employees (Incorrect - unrelated to coordination) 5. Outsourcing a) Hiring external companies or individuals to perform specific tasks or functions (Correct) b) Expanding business operations to international markets (Incorrect - refers to a different concept) c) Merging with other companies to form a larger entity (Incorrect - unrelated to outsourcing) d) Expanding the scope of in-house operations (Incorrect - opposite meaning of outsourcing) 6. Inspection a) Examining and evaluating suppliers, products, or processes to ensure compliance with quality standards (Correct) b) Promoting new products through advertising campaigns (Incorrect - unrelated to inspection) c) Conducting market research to understand customer preferences (Incorrect - unrelated to inspection) d) Developing prototypes for new products (Incorrect - unrelated to inspection) 7. Efficiency a) Accomplishing tasks or goals with minimum waste of time, effort, or resources (Correct) b) Maximizing profits through aggressive pricing strategies (Incorrect - unrelated to efficiency) c) Expanding business operations to new markets (Incorrect - refers to a different concept) d) Streamlining organizational hierarchy through downsizing (Incorrect - unrelated to efficiency) 8. Expertise a) Specialized knowledge or skill in a particular field or area (Correct) b) Broad knowledge across multiple disciplines (Incorrect - opposite meaning of expertise) c) Entry-level knowledge and skills (Incorrect - unrelated to expertise) d) General knowledge applicable to various industries (Incorrect - opposite meaning of expertise) 9. Trend a) General direction or pattern of change or development over time (Correct) b) A one-time occurrence or isolated event (Incorrect - opposite meaning of trend) c) A static and unchanging state (Incorrect - opposite meaning of trend) d) A minor fluctuation in a stable market (Incorrect - unrelated to trend) 10. Demand a) Desire or need for a particular product or service (Correct) b) The quantity of a product produced by a company (Incorrect - refers to supply, not demand) c) The pricing strategy employed by a company (Incorrect - unrelated to demand) d) The promotional activities carried out by a company (Incorrect - unrelated to demand)
Make mcq quiz with 4 option in which one is correct -'10 Basis of Material Science • .....;;;";;;"~~;;,,;;,,,,;.;.,,;;,,,;,,;.;,.,------------ 6. Temporary materials: Some materials are meant to be placed in the oral cavity for a short period of time for different reasons. • Temporary crowns: While a permanent crown is prepared in the dental laboratory, the patient must wait for few days before it can be fabricated and cemented into place. Does patient experience any problems during this time period? If the tooth is vital (the pulp is alive), the patient is likely to experience pain and sensitivity while eating and drinking, also it looks unesthetic. What can be done to solve this problem? A temporary crown is placed before the patient leaves the clinic. It is constructed and luted in the same appointment in which the crown preparation is done. Temporary crowns are not very strong or esthetic but they serve adequately till the permanent crown is ready to be cemented. • Temporary restorations: Sometimes it is difficult to decide immediately the best line of treatment for a particular tooth. The exact condition of the pulp may not be obvious to the dentist from the patient's symptoms. A dentist removes all or part of the decay and then places a temporary restoration to have time to observe the behaviour of the pulp or to give the pilip time to heal before deciding the further treatment required. Classification based on Location of Fabrication 4,9 Materials can be classified based on the location of fabrication into: • Direct restorative materials. • Indirect restorative materials Direct restorative materials: They include those materials which are used to restore cavity preparations directly in the oral cavity (Box 1.5). Box 1.5: Examples of direct restorative materials Amalgam, composites, glass ionomer and other materials, which set by chemical reactions in the mouth. Indirect restorative materials: It includes those restorations which must be fabricated outside the mouth, indirectly on a cast/ model/ die, because their processing condition would harm oral tissues. Materials used in the construction of such prosthesis are called indirect restorative materials (Box 1.6). Box 1.6: Examples of indirect restorative materials Gold inlays, crowns of metal, ceramic and polymers, which are processed at elevated temperatures. Some indirect composite restorations can be processed under specific wavelength of light, e.g. Ceramage. Classification based on Longevity of Use 1. Permanent restorations: These restorations are not planned to be replaced for a particular time period. Though they are referred to as permanent, actually they are not, e.g. fillings, crowns, bridges and dentures do not last forever (Fig. 1.5). 2. Temporary restorations: These restorations are planned to be replaced in a short period of time, such as few days to weeks. For ~ Permanent C/) c c -.2 0 c- :;::; Cll co Interim ~ Q; 0 .8ll::1iJ C/) o~ Cll a:: c:=:J Temporary Time period Fig. 1.5: Diagram depicting the time period of use of a restoration. (Arrow in permanent restoration depicts that such restorations are not planned to be replaced for a long period of time.) Introducton to Dental Materials Dental materials Box 1.7: Characteristics of metals 1. High thermal and electrical conductivity 2. Ductility (pure metals are very soft and they can be bent without breaking) 3. Opacity (they do not transmit light) 4. Luster (they have a surface that strongly reflects light and appears bright and shiny) 5. They tend to dissolve to some extent in water or other aqueous solutions, producing cations. 6. All metals are white (actually gray) except for gold, which is yellow, and copper, which is reddish. 7. All metals are solid at room temperature except mercury, which is liquid at room temperature and is used with silver alloys as amalgam. 8. All metals have high melting temperatures because of high strength of the metallic bond that holds the atoms together. 3. Polymers 4. Composites Composites are mixtures of two or more of the first three classes in which the different components remain distinct from one another in the final structure. A common example is composite resin. Fig. 1.7a: Three-dimensional structure of iron (metal) Metals Metals are the oldest of the three classes of materials that have been used as dental materials. Metals are characterized by metallic bonds (Box 1.7) which will be discussed in the next chapter. Metals solidify with their atoms in a regular or crystalline arrangement (see Chapter 2), often in the form of a cube (Fig. 1.7a). example, temporary fillings done in a tooth during root canal treatment, which have to be replaced within 2-4 days during subsequent visits. They are used to protect the tooth and provide function till the final restoration is done. 3. Interim restoration: At times, dental treatment requires "long-term" definite temporary restorations or "interim" restorations. For examle, a 7-year-old child, met with trauma and fractured one of his central incisors. A large composite build- up may serve his immediate requirement until the root formation is completed and a permanent crown is placed. 5 Classification based on the Chemical Nature of the Material These are the atoms that make up a material and the way they are bonded together determine the properties of that materiaLS Weak bonds make for weak materials and vice versa (Table 1.4). Materials can be classified into different categories based on their primary atomic bonds (Fig. 1.6): 1. Metals 2. Ceramics Fig. 1.6: Classification of dental materials based on chemical nature 12 Basis of Material Science Box 1.9: Benefits of ceramics in dentistry 1. Many ceramic oxides are used as pigmenting agents. These oxides produce good range of colors. Due to this characteristic, we are able to match almost any tooth color with good esthetic results. 2. They are inert, i.e. not chemically reactive. This quality provides ceramics with good bio- compatibility. 3. Ceramic materials are translucent, like natural teeth. This translucency gives the ceramic crown a more natural appearance than any other dental material. Fig. 1.7b: Internal arrangement of tetrahedral structure of ceramic (silica) four large oxygen atoms surround smaller silicon atom Ceramics A ceramic is a compound formed by the union of a metallic and a non-metallic element (Box 1.8). Most of these materials are oxides, formed by the union of oxygen with metals such as silicon, aluminum, calcium and magnesium (Fig.1.7b). Ceramics may be simple or complex. Examples of simple ceramics are alumina and silica. Examples of complex ceramics are feldspar (potassium aluminum silicate) and kaolin (hydrated aluminum silicate). Ceramics may be crystalline or non- crystalline (i.e. amorphous). Porcelain is a specific type of ceramic used extensively in dentistry (Box 1.9). Box 1.8: Characteristics of ceramics 1. High melting points. 2. Brittleness, which means they cannot be bent or deformed (no sliding) to any extent without actually cracking and breaking. 3. They are poor conductor of heat and electricity. 4. They are chemically inert. 5. They have excellent esthetic result in terms of matching natural teeth. Fig. 1.8: Stucture of synthetic polymer Polymers They are the latest addition (early to mid- 1900s) to dental materials. Most of the polymers are nowadays synthesized by humans. Polymers are giant, long-chain organic molecules (Fig. 1.8). Polymers are characterized by covalent bonds within each molecule, giving them tremendous strength in a single direction. Try to break a nylon rope by pulling it! They are poor conductors of heat and electri- city. Most polymers have a structure containing thousands of carbon atoms linked together like beads on a string. Others, such as silicone polymers are formed with silicon-oxygen bonds. Introducton to Dental Materials Table 1.4: Characteristics of different materials 13 Characteristics Bond Properties Crystal structure Metals Metallic bonding High strength and hardness, high electrical and thermal conductivity BCC, FCC, or HCP unit cells Ceramics Ionic or covalent bonding, or both High hardness and stiffness, electrically insulating, refractory, and chemically inert Crystalline or amorphous Polymers Covalent bonding Low sensitivity, high electrical resistivity, and low thermal conductivity, strength and stiffness vary widely Amorphous and crystalline Composites Composites are combinations of any of the basic ceramic, metallic and polymeric materials (Box 1.10). Each material that makes up composites is called a phase. Their properties tend to be somewhere between those of their basic constituents and are used to enhance their performance, longevity and handling chracterstics. Box 1.10: Types of composites in dentistry 1. Ceramic - metallic composite: Tungsten carbide bur. 2. Metal - polymer composite: Die materials in dental laboratory. 3. Ceramic - polymer composite: Enamel, dentin, bone and restorative composites. A composite is a kind of "combination" of materials, which compliment each other. The properties lacking in one material are compensated by those of the other material. For example, restorative composite has two phases, namely resin and fillers. Teeth and bones are examples of natural composites. Enamel is a composite of hydroxyapatite (which is a ceramic material) and protein (which is a polymer). EVALUATION OF DENTAL MATERIALS Most manufacturers of dental materials maintain a quality assurance programme (As per international standard like ADA specifications) and materials are thoroughly tested before being released into the market for dental practitioner (Fig. 1.9). Laboratory Evaluations Most ADA/ ANSI specifications involve laboratory tests. The tests performed as per these specifications are useful but they all are performed in vitro, (carried out in the laboratory away from the clinical conditions) which have a lot of limitations in clinical practice.lO Clinical Notes 1. For example, most of the direct restorative materials are tested for their compressive strength but ultimately the material is subjected to a combination of compressive, tensile and shear stresses, which may decide the final success or failure of the material under masticatory load. 2. Similarly upper dentures mostly fracture along the midline because of bending. Hence a bending or transverse strength ~B-a-s-is-o-f-M-a-t-e-ria-I-S~c-ie-n-c-e-------------- ---------. test is far more meaningful for denture base materials than a compression test. Clinical Trials The majority of new materials are subjected to extensive clinical trials normally in co-operation with a dental college or hospital departments prior to their release. CONCLUSION As the number of available materials is going up, it is important that the dentist remains more aware about new products so that their judgement about the selection of material remains successful. Materials which have not been thoroughly evaluated should be avoided, specially with clinical dentistry falling under Consumer Protection Act (CPA). I Research and development I iI Manufacturer/analysis Ideal requirements for clinical use: Thermal, optical, mechanical, chemical, biological Available materials and their properties are evaluated Launch of new I product Choice and selection of material by the dentist Critical assessment based on clinical performance I I H feedback to I