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Direct or Indirect?
QuizĀ by Coleen Colton
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DIRECT OR INDIRECT
PREASSESSMENT DIRECT OR INDIRECT SPEECH
Introduction to Decolonization and Nationalism Lesson Vocabulary colony (n) an area over which a foreign nation or state extends or maintains control. colonize (v) to take control of(a people or area, especially as an extension of state power. control (v) to exercise restraining or directing influence over. decolonize (v) to free or give up control of a colonized people or area. empire (n) a major political unit having a territory of great extent or a number of territories or peoples under a single sovereign authority. Ex. Roman Empire, Ottoman Empire human rights (n) rights (such as freedom from unlawful imprisonment, torture, and execution) regarded as belonging fundamentally to all people. imperialism (n) the policy, practice, or advocacy of extending the power and dominion of a nation, especially by direct territorial acquisitions or by gaining indirect control over the political or economic life of other areas. independence (n) a state of being free from direct control by others. majority (n) being over 50% of a population OR the group with the greater amount of power in a political entity. minority (n) being less than 50% of a population OR the group with less power than the majority in a political entity. nation (n) a politically organized group of people with shared characteristics, such as language, culture, or geographic origins. nationalism (n) a movement that seeks to unify or promote the interests of a nation or national group. nonviolence (n) a movement that completely abstains or avoids violence as a means of political protest. oppress (v) to crush or burden by abuse of power or authority. political movement (n) a group of people who seek to organize people to change government, policy, or social values. protest (n) an organized public demonstration of disapproval. reform (n) removal or correction of errors or of an abuse or a wrong. state (n): an organization that has a system in which a politically organized group of people have primary control over a definite territory. Definitions mostly used: Merriam-Webster
The advantage of direct method is that the teacher can control the class and fit in a lot of activity into a short class period. This leaves plenty of opportunities for the students to hone their skills, especially new ones. On the other hand, because the class is centered around the teacher, some students may not receive proper feedback, and creativity is limited. Also, the lesser talented athletes often tend to get lost in the shuffle while the great athletes shine. However, there are now a multitude of various teaching strategies that can be employed in addition to that method. Ex: Announcements, Module/Unit introductions, Descriptions/modeling of assignments and learning activities, Written or video lectures, Demonstration videos, Presentations, Discussions moderated by instructors, Interactive tutorials. Indirect Method The Indirect Teaching Style allows students to be involved in their own learning through experience and other peerās knowledge. Students can use critical thinking to expand their learning capabilities by seeing what others may be doing correct and adjusting this to their own knowledge. The Indirect approach is the opposite of what the direct style suggests, but they are both strictly related, meaning you canāt have one without the other. Direct teaching: The instructor stands in front of the class or group and lectures or advises. Indirect teaching: The instructor assumes a more passive role and guides the student interactions. Movement exploration: Incorporates the use of equipment that involves movement. Movement Exploration The movement exploration class is founded on developing a strong, positive association to physical activity. Classes are aimed at developing movement skills and foundational strength through fun and engaging activities. The activities are age appropriate and include games, challenges, and exploration that positively challenge childrenās competency while improving their physical capabilities. Skills such as the ability to climb, hold animal shapes, gymnastic style activities, and the introduction to athletic motor skill competencies are the foundations to youth training. This class provides the introduction to strength training to give children the opportunity to learn the skills required to safely and confidently engage in resistance training. Cooperative Skills Cooperative activities teach students to work together for their group's common good. By participating in these activities, students can learn the skills of listening, discussing, thinking as a group, group decision making, and sacrificing individual wants for the common good. There are two primary objectives guiding the teaching of cooperative activities. First, cooperative activities allow students to apply a variety of fundamental motor skills in a unique setting. Students are typically asked to perform motor skills in a specific way, such as āskip in general spaceā or ābalance on one foot and one elbow.ā Cooperative activities ask students to perform different activities such as skip with their hands on the shoulders of someone in front of them, walk with big steps while placing their feet on small spots, or walk across an area blindfolded while someone directs their moves. Due to the uniqueness of such experiences, students often find cooperative activities exciting and motivating. Second, cooperative activities are a wonderful medium for teaching social and emotional learning (SEL). SEL offers students an opportunity to understand and manage their emotions. In addition, such activities offer an opportunity to show empathy for others and develop positive relationships. Cooperative activities demand that all students play a role in completing the task or solving the movement problem. Every student, regardless of ability level, is important and contributes to group goals. 9 traits a PE teacher often needs Here are nine essential traits of an effective PE teacher: 1. Athletic ability Athletic ability is an essential trait for a PE teacher because they're often showing kids how to perform exercises. To demonstrate proper form and encourage the kids to continue their fitness education, it's important they can perform the exercises themselves. Having experience with fitness training can enhance a PE teacher's lesson planning because they're familiar with how each exercise affects a person's body. Athletic ability can also refer to an aptitude for sports and games. PE teachers can instruct students on how to play these games or lead after-school activities involving them, like soccer or basketball. An aptitude for sports and games can help a PE teacher encourage students to participate in the activities during class. If the PE teacher enjoys physical activity, they may make the lessons more enjoyable for the student. 2. Teaching ability A PE teacher is a member of a school faculty, so it's essential they have the teaching ability that allows them to communicate lessons to students. There are various skills involved in teaching, including the technical capabilities associated with each professional's particular field. Learning these skills can help PE teacher plan their lessons effectively and connect with their students, meaning they can encourage students to practice fitness skills in optimal ways for their health. Here are some important teaching skills for PE teachers: Having an engaging classroom presence ļ· Real-world learning ļ· Project building ļ· Lesson planning ļ· Technology 3. Interpersonal skills PE coaches are part of faculty teams, so working alongside other teachers is an essential part of their job. They often collaborate with a student's general education teacher to address any behavioral issues that arise. They can also team up with other classes to plan activities for students, like field days and special field trips. Communicating with peers can ensure these interactions remain productive and create opportunities for more fulfilling lessons. Teachers can also model emotional skills for their students by displaying positive social interactions. Interpersonal skills can also help PE teachers interact with students and their families. If a student can make a student feel comfortable expressing their needs and preferences, they can often perform physical exercises or play games to the best of their individual capacities. Understanding how to soothe nerves and support students' emotional needs are important examples of interpersonal skills. When interacting with family members, you may use some of these same techniques to communicate effectively and best uplift students. 4. Written and verbal communication Both verbal and written communication is important for PE teachers because they often communicate with students, families and various personnel on a day-to-day basis. For example, a PE teacher uses their communication skills in a lesson plan to describe any student assignments or expectations accurately. They may also write instructions in a document, then explain them in a classroom lecture. They also use communication skills to share their lesson plans with other PE teachers during conferences or classroom development exercises. Many teachers continue to learn their trade even after working as a teacher for many years. They may share tips with each other or special lessons they've developed if they feel another teacher may benefit from it. Creating a community can help PE teachers continue to expand their teaching methodology and receive feedback on their lessons. 5. Patience and adaptability Working with children can require patience and adaptability because they're encountering many new concepts at the same time and learning how to regulate their emotions. As a result, it's important to treat them with patience and care while they're in your class so they can feel comfortable and feel motivated to complete assignments. As children become teenagers, they may require patience and adaptability to account for their changing bodies and attention spans. Like any job where you perform tasks in real-time, certain circumstances may occur that require you to adapt lesson plans. For example, if the weather turns from sunshine to rain on a day you planned for students to run a mile outside, you may need to adapt the lesson plan so they can practice endurance sports inside a gymnasium instead. 6. Organization PE teachers can use organization skills to improve their lesson planning sessions. For example, they can keep their plans in one place, and determine which parts of a semester or quarter to introduce new concepts. Throughout the year, these objectives may change because of unforeseen setbacks, but organizational skills can help PE teachers control the trajectory of their class curriculum. PE teachers can also use organizational skills to maintain their classroom space. Physical education frequently requires balls, equipment and tools to play games that may be on a lesson plan. They also organize equipment and decide where to store it within their classroom or storage space. 7. Creativity Creativity can help a PE teacher develop fun ways to introduce new material to their students or reinforce previous lessons. They can teach new games or devise interesting ideas to change the rules of a game to help keep students engaged. To find inspiration for their lesson plans, they can turn to personal hobbies or media aspects they enjoy, like movie scenes, songs or dances. A varied lesson plan can foster more engagement among students who prefer action- based learning activities, rather than lectures. 8. Focus Focus is an essential trait of a PE teacher because students often require their full attention during class, especially if they're learning a complicated physical task. You can focus your lesson plans around specific elements of physical education you believe are essential for students of a certain age group or skill level. If students require mentorship, you can also focus on each student's needs to supply them with a steady support system. Focusing on your students can help guide your career purpose. It can give you a core value system that informs your lesson plans and mentorship activities. This passion for your student's well-being can also help you become an advocate for each student in your class. You can also help organize funding for different field trips or establish after-school activities to support their interests. 9. Enthusiasm for teaching sports and fitness Enthusiasm is essential for a PE teacher. Many physical education activities require high energy and may suit someone who enjoys teaching them to others. Being an effective PE teacher also requires an enthusiasm for working with kids and making a positive impact on their lives.
A1.ACE.2* Create equations in two or more variables to represent relationships between quantities. Graph the equations on coordinate axes using appropriate labels, units, and scales. (Limit to linear; quadratic; exponential with integer exponents; direct and indirect variation.)
Earlier in 2019 there was a lot of femicide uh girls being killed by their boyfriends because they did one or two things there are also cultures of if there is violence in terms of a marital relationship that that is fine if there's a marital rape that that is fine so you find such situations being normalized and it being also a taboo to speak about those issues the 2030 agenda for sustainable development is grounded in respect for human rights and the power of people to change the world every individual on the planet has the right to health and well-being in all aspects of their sexuality their body and their reproductive choices ensuring these rights is integral to addressing poverty education violence against women and gender equality sexual and reproductive health rights are agreed in international law they were fought for by courageous women's rights activists and advocates across a broad range of professional fields and frontline experiences by movements of all ages levels and backgrounds they are still being fought for while progress has been made globally many barriers remain especially for those most marginalized excluded or discriminated against human rights are central to delivering the 17 sustainable development goals in the sustainable development agenda indeed each sdg target is simultaneously a metric and a claim for human rights the interplay between these political commitments and human rights obligations is particularly important when it comes to achieving sexual and reproductive health rights for decades human rights-based tactics have been used to drive progress in this episode of right to a better world experts share challenges they have faced and tactics they have used to address them the challenges they describe occur in settings all around the world the strategies used are ones that they have found to be successful in their own settings viewers are encouraged to learn from these experiences and consider how tactics could be adapted to their own context when sexual and reproductive health begins with equality the discussions decisions programs and policies which follow can build towards a future where every individual is not only born free but lives free and equal in dignity and rights without violence or discrimination the time to take action is now violence against women is any act that results in or is likely to result in physical sexual or psychological harm or suffering to women this includes threats of such acts coercion or arbitrary deprivation of liberty in public or private life it happens everywhere in every country in the home in communities at work and at school crises including health and humanitarian crises frequently contribute to higher rates of violence against women violence against women is directed at women because of their status as women the consequences are dire jeopardizing women's health including sexual and reproductive health and mental health hampering their ability to participate fully in society causing tremendous physical and psychological suffering for both women and their children the majority of women survivors of violence do not disclose or seek any type of services efforts to address violence against women must recognize the many different contexts in which it occurs and the many different forms it can take the majority of violence against women is committed by an intimate partner her current or previous boyfriend or husband globally around 30 of women have experienced physical and or sexual violence by an intimate partner in their lifetime this increases the risk of acquiring an sti or in some regions hiv by 1.5 fold when a woman is experiencing violence especially from her partner she's really unable to keep safe from hiv men have power to decide how when and where sex should be done and the woman is at risk of being infected because she cannot say no schools are another setting where violence against girls can take place assault and harassment during their commute bullying sexual harassment and mental or physical abuse on school property are all challenges across various country contexts this has a direct impact on girls access to inclusive quality education a target of sdg4 and an indirect impact on many of their other human rights young girls are taking advantage of at a very young age and they do not understand the choices and the avenues whereby they can exercise their rights when it comes to sexual productive health and rights and so you find a lot of dropouts and a lot of girls also going through a lot of traumatic experiences that would be avoided if they had guidance promoting a safe and secure working environment for all is a cornerstone of sdg 8. this includes a workplace free from sexual harassment and violence but for many women especially women migrant workers and others in precarious employment this is far from reality so we went to naivasha which is a flower farm and we've met the informal workers the casual liberals working for the flower farms when for example the sexual violence cases are reported companies don't take them very seriously a wide range of tactics have been used to prevent and address violence against women and girls and to recognize it as a fundamental violation of human rights prevention of intimate partner violence is possible when interventions are informed by evidence of what works we started out by describing the problem we've now moved to research on what works what are the kinds of interventions that are successful both for preventing the problem from happening in the first place and also from interventions to respond the respect women framework on preventing violence against women developed by the who un women ohchr and other international agencies promotes seven strategies which focus on relationship skills strengthening empowerment of women services for health justice police and social sector poverty reduction environments made safer including schools workplaces and public spaces child and adolescence abuse prevented and transformation of gender attitudes beliefs and norms this action-oriented framework can enable policy makers and health implementers to design plan implement monitor and evaluate interventions and programs to prevent violence against women we have come a long way for sure we still have some ways to go and we need to do more to stop this violence from happening in the first place this involves addressing the social norms that still prevail in many settings that make this form of violence acceptable women are not exposed to gender-based violence by accident all because of an inbuilt vulnerability violence against women is rooted in discriminatory social norms and power dynamics dismantling these underlying causes of violence against women and girls is at the heart of achieving gender equality and empowering all women and girls as set out in the targets and indicators of sdg 5 ensuring healthy lives in sdg3 and reducing inequalities in sdg 10. women and men are valued differently society has heap privileges on the men while the women are looked at as subordinate power is not only the problem but also the solution to preventing violence against women we are making it personal everyone connects with power every day people living with power or grappling with power they find themselves within this whole conversation if you're working to create gnome change there has to be change at all levels strategies to raise awareness in communities about violence against women and girls are critical as there is still a lot of stigma and shame which inhibits many women and girls from talking about it intervention is like a big complicated word sometimes it's just about talking about dialogue i mean the fact that we went into schools and just began a conversation with parents um bringing them together in the school along with the school personnel and then having the conversation start from there and we also sort of train providers within schools to appropriately refer children to health facilities for care what we found was that this dialogue began to spark other conversations in the community and i guess they just felt that oh it's actually okay to talk about this openly rather than pretend that nothing is going on sassa is a community mobilization approach to prevent violence against women and hiv and aids it is activist led it's not workshop heavy based it comes away from the traditional programming of organizations going to do things themselves instead they support activists who do the activities with their friends and neighbors health systems play a critical role in responding to violence wherever it occurs supporting health workers to respond appropriately to violence as well as ensuring their work environment enables them to provide safe effective and quality survivor centred care are important strategies for better addressing violence against women and girls um we came to learn not to ask direct questions not to give our opinion or our judgment on them and let her speak and once with that flow starts once that connection is established that doctor-patient relationship emotionally is established she will actually tell you the whole history legal frameworks to promote enforce and monitor equality and non-discrimination on the basis of sex are an important sdg 5 indicator but putting laws in place does not automatically make them effective there are existing protections for women in the workplace or for individuals in the workplace in relation to harassment but we know from our call for evidence that they are not actually addressing the problem the recommendations that we developed included government implementing a mandatory duty for employers to take preventative steps to address harassment in the workplace so what we would like to see is government implement a much stronger legislative duty it has taken decades of struggle by the women's rights movement to persuade the international community to view violence against women as a human rights concern and a sustainable development priority not a private matter governments have obligations to respect protect and fulfill the right to a life free of violence and to provide for sanctions when they fail when seeking accountability the priority consideration must always be the safety and well-being of survivors respecting their wishes and autonomy and supporting them to make informed choices about the type of justice they want context is vitally important there are many strategies to hold perpetrators accountable including strategic litigation and public campaigns when the teachers impregnate the girls that means the system has failed and okay what they do is they blacklist the teachers and they are always removed from the payroll but we think that is not enough the case that was quite interesting is where one of the judges she did find a ruling against the teacher service commission the commission that is responsible for hiring teachers asking them that they must take responsibility and they were ordered to pay compensation to the girls who had gotten pregnant while in school the justice police issue came about a few years back when a young girl was raped and the punishment for her being ripped was that harappa she was gang-ripped and therapists were told to slash grass feminist organizations and young women organizations came back to the police and the police commissioner to ask and request that the people who are found to be perpetrators should be punished according to our constitution and according to the laws of the land and those are very big campaigns to get better justice so consequently they were jailed but also it was a sign that the system the police system had to be checked in terms of when someone reports a case any case of violence what happens and how is it followed through the maria pedra is another example of litigation that became a political mobilizer so this was a case from the inter-american commission that really galvanized a change in public policy a huge change because it was a case that addressed gender-based violence intimate partner violence it called on responsibility of brazil also for not having prevented this kind of violence the reality of a case that says you have the right to not be bruised you have the right to be free of physical psychological violence it's powerful it can change women's lives investing in autonomous women's movements has been one of the most important drivers of changes in laws and policies to address violence against women over the past 40 years according to data from over 70 countries women organizing to advance women's status define the very concept of violence against women raised awareness of the issue and put it on national and global policy agendas often we thought that it takes generations or centuries to change working intensely with the communities we can actually see change coming violence against women and girls is a violation of fundamental human rights to life and to physical and psychological integrity not to be tortured or treated in an inhuman and degrading way to respect for private and family life and the right not to be discriminated against this understanding is more than theoretical human rights-based tactics can offer a practical route to addressing systemic challenges across all the circumstances where violence against women and girls occurs including but not limited to at the hands of their partners at school and in the workplace by using evidence-informed prevention strategies addressing power relations and social norms community mobilizing and dialogue supporting health systems and professionals putting in place strong legal frameworks accessing justice and ending impunity feminist organizing and mobilizing every individual can help to deliver the 2030 agenda for sustainable development building a world in which women and girls are free from all forms of violence and discrimination [Music] you
7.03 Patients with Infectious Disease The center adheres to infection control policies to ensure the safety of patients, physicians, and staff members. Patients who are currently being treated for an infectious disease or condition that is transmitted via the contact route may not be treated at the center. Patients with disease spread via droplet (e.g. influenza) or airborne (e.g. tuberculosis, measles) routes will reschedule their procedures in consultation with their physicians. The infection control nurse, in consultation with the infection control consultant, will determine whether the patient requires isolation or other additional precautions. If a patient with current Clostridium difficile-associated diarrhea is treated at the center, all rooms where the patient was housed, even briefly, should be cleaned by housekeeping under supervision of the staff at the center. Physicians must document relevant information in their pre-admission documentation. Standard Precautions will be followed in the care of all patients. Cigarroa Interventional Institute establishes policies to ensure compliance with infection control policies for the care of patients with drug-resistant organisms. The physician will screen patients through the medical history review prior to scheduling a patient at the center. During the pre-operative (pre-op) phone call or interview, a pre-op screening of the patient will be conducted. Strict isolation policies are required to treat patients with active MRSA, VRSA, or tuberculosis. Since this facility has no provisions for strict isolation, those patients with active infections will be referred elsewhere for treatment. Patients who are undergoing or completed a course of antibiotic therapy, are colonized and/or are not actively infected may be treated at the center. Patients with active infections requiring transmission-based precautions are not appropriate candidates for this facility and will be referred to another facility or rescheduled. Procedures cannot be scheduled for patients currently undergoing an infection with transmission based precautions. The patient must finish the course, and they will be rescheduled. Definitions and Standards: The following definitions and standards are provided for informational purposes only: Airborne Transmission and Precautions: This mode of transmission occurs by the spreading of either airborne droplet nuclei (small particle residue of 5 microns or smaller), of evaporated droplets which contain microorganisms that remain suspended in the air for long periods of time) or dust particles containing microorganisms. Patients must be isolated in private rooms with special air handling and ventilation, and the door must remain closed. Patient transport should be restricted to essential transport only. Respiratory precautions must be taken when in the presence of patients with active tuberculosis, including respiratory masks. Droplet Transmission and Precautions: Droplets are transmitted from the host source by coughing, sneezing, talking, or during procedures such as suctioning or bronchoscopy. Patients must be isolated, and a distance of 3 feet maintained between the infected patient and others. Caregivers within 3 feet of the patient should wear a mask. Patient transport should be minimized. Contact Transmission and Precautions: Direct contact transmission involves direct body surface to body surface contact with physical transfer of microorganisms between a susceptible host and an infected person. Indirect contact transmission involves contact with an intermediate object (usually inanimate) and a susceptible host. Patients should be isolated as much as possible. Gloves and hand washing are essential for all contact with the patient and contact with objects, which come in contact with the patient. Gloves should be changed after each contact. Reportable Condition If the patient is determined to have a reportable condition at any time during pre-admission, the Director of Operations/Nurse Manager will be notified. The procedural physician will be contacted and the case will be canceled. The Department of Health will also be notified the same day following state regulations regarding Reportable Communicable Diseases. To report a disease or condition, contact: The City of Laredo Epidemiology 24/7 Reporting Line: (956) 763-2915, if unable to report locally, call The Texas Departmrent of Health Services epidemiology program: 24/7Number for Immediately Reportable ā 1-800-705-8868
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