Indian Dental Academy: will be one of the most relevant and exciting training center with best faculty and flexible training programs for dental professionals who wish to advance in their dental practice,Offers certified courses in Dental implants,Orthodontics,Endodontics,Cosmetic Dentistry, Prosthetic Dentistry, Periodontics and General Dentistry.
Soldering and welding are the integral part of dentistry specially in prosthodontics and crown and bridge procedure. it is also used in implant supported prosthetic.
Soldering and welding are the integral part of dentistry specially in prosthodontics and crown and bridge procedure. it is also used in implant supported prosthetic.
2- b. Basic principles for designing Kennedy class II, III and IV Removable P...AmalKaddah1
1-a. Basic principles for designing the removable partial denture (class I partial denture design)
Introduction.
Objectives and Functions of RPD.
Factors that affect RPD design.
Basic principles for designing Kennedy class I partial denture.
2- b. Basic principles for designing Kennedy class II, III and IV Removable Partial Denture(RPD)
Description :
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
A comprehensive slideshow covering all the basics relating to dental materials and their physical properties. Based on standard text books - Phillips Science of Dental Materials (11th Edition).
Biological properties of dental materials 1 /certified fixed orthodontic cour...Indian dental academy
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.
Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
0091-9248678078
Description :
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
2- b. Basic principles for designing Kennedy class II, III and IV Removable P...AmalKaddah1
1-a. Basic principles for designing the removable partial denture (class I partial denture design)
Introduction.
Objectives and Functions of RPD.
Factors that affect RPD design.
Basic principles for designing Kennedy class I partial denture.
2- b. Basic principles for designing Kennedy class II, III and IV Removable Partial Denture(RPD)
Description :
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
A comprehensive slideshow covering all the basics relating to dental materials and their physical properties. Based on standard text books - Phillips Science of Dental Materials (11th Edition).
Biological properties of dental materials 1 /certified fixed orthodontic cour...Indian dental academy
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.
Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
0091-9248678078
Description :
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
Abrasive and polishing agents/certified fixed orthodontic courses by Indian d...Indian dental academy
Description :
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
Description :
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
Description :
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
Description :
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
It occurs when a hard, rough surface slides along a softer surface and cuts a series of grooves.
The wearing away of a substance or structure through a mechanical process, such as grinding, rubbing or scraping .
Polishing is production of smooth mirror like surface without use of any external form.
Indian Dental Academy: will be one of the most relevant and exciting training center with best faculty and flexible training programs for dental professionals who wish to advance in their dental practice,Offers certified courses in Dental implants,Orthodontics,Endodontics,Cosmetic Dentistry, Prosthetic Dentistry, Periodontics and General Dentistry.
Indian Dental Academy: will be one of the most relevant and exciting training center with best faculty and flexible training programs for dental professionals who wish to advance in their dental practice,Offers certified courses in Dental implants,Orthodontics,Endodontics,Cosmetic Dentistry, Prosthetic Dentistry, Periodontics and General Dentistry.
Finishing and polishing of cast metal framework/prosthodontic coursesIndian dental academy
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
Finishing & Polishing Materials by Dr Rashid HassanDr Rashid Hassan
A comprehensive lecture on finishing and polishing materials by Dr Rashid Hassan covering all the aspects of the topic from basic concepts to the applications in dentistry.
For more lectures on different topics of Dental Materials by Dr Rashid visit and follow Dr Rashid lectures on Dental Materials on Facebook (dmbydrrashid)
Indian Dental Academy: will be one of the most relevant and exciting training center with best faculty and flexible training programs for dental professionals who wish to advance in their dental practice,Offers certified courses in Dental implants,Orthodontics,Endodontics,Cosmetic Dentistry, Prosthetic Dentistry, Periodontics and General Dentistry.
Opportunity for Dentists (BDS/MDS )to relocate to United kingdom -Register as a DENTAL HYGIENIST/ DENTAL THERAPIST without Board exams and after approval you can register in GDC as a DH/DT and start working as a DH/DT Immediately and get paid.
You can complete the whole process in 3-4 months.Salary range for DH/DT is around 2500-3500 Pounds per month.
Eligibility / requirements-
1. An International English Language Testing System (IELTS) certificate
at the appropriate level.(Within 2 yrs of application date )
2: A recent primary dental qualification that has been taught and examined in English..(Within 2 yrs of application date )
3: A recent pass in a language test for registration with a regulatory authority in a country where the first language is English.
If you are interested Please contact us for more details.
1ST, 2ND AND 3RD ORDER BENDS IN STANDARD EDGEWISE APPLIANCE SYSTEM /Fixed ort...Indian dental academy
Indian Dental Academy: will be one of the most relevant and exciting training center with best faculty and flexible training programs for dental professionals
who wish to advance in their dental practice,Offers certified courses in Dental implants,Orthodontics,Endodontics,Cosmetic Dentistry, Prosthetic Dentistry,
Periodontics and General Dentistry.
Indian Dental Academy: will be one of the most relevant and exciting training center with best faculty and flexible training programs for dental professionals who wish to advance in their dental practice,Offers certified courses in Dental implants,Orthodontics,Endodontics,Cosmetic Dentistry, Prosthetic Dentistry, Periodontics and General Dentistry.
I –Aligners are made with FDA approved transparent thermoplastic materials using 3D scanning, 3D Printing and finally Trays with Pressure vacuum formers.
Dear Doctor,
Indian Dental Academy Now offers comprehensive online Orthodontics course.
Course includes:
1.whiteboard lecture presentations
2.Case Discussions
3.with hundreds of pictures.
4.Demo on Models
5.Demo on Patients
6. subtitles in your own language
12 months unlimited access and support @350 USD only.
For Demo please visit :www.idalectures.com/preview/
For more details visit: www.idalectures.com
Please contact us for any clarifications:
idalectures@gmail.com
indiandentalacademy@gmail.com
Thanks & Regards
Indian Dental Academy
--
Indian Dental Academy
Leader in continuing dental education
www.indiandentalacademy.com
skype:indiandentalacademy
+919248678078
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
Cytotoxicity of silicone materials used in maxillofacial prosthesis / dental ...Indian dental academy
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
Diagnosis and treatment planning in completely endntulous arches/dental coursesIndian dental academy
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
Properties of Denture base materials /rotary endodontic coursesIndian dental academy
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
Use of modified tooth forms in complete denture occlusion / dental implant...Indian dental academy
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
Unveiling the Secrets How Does Generative AI Work.pdfSam H
At its core, generative artificial intelligence relies on the concept of generative models, which serve as engines that churn out entirely new data resembling their training data. It is like a sculptor who has studied so many forms found in nature and then uses this knowledge to create sculptures from his imagination that have never been seen before anywhere else. If taken to cyberspace, gans work almost the same way.
Enterprise Excellence is Inclusive Excellence.pdfKaiNexus
Enterprise excellence and inclusive excellence are closely linked, and real-world challenges have shown that both are essential to the success of any organization. To achieve enterprise excellence, organizations must focus on improving their operations and processes while creating an inclusive environment that engages everyone. In this interactive session, the facilitator will highlight commonly established business practices and how they limit our ability to engage everyone every day. More importantly, though, participants will likely gain increased awareness of what we can do differently to maximize enterprise excellence through deliberate inclusion.
What is Enterprise Excellence?
Enterprise Excellence is a holistic approach that's aimed at achieving world-class performance across all aspects of the organization.
What might I learn?
A way to engage all in creating Inclusive Excellence. Lessons from the US military and their parallels to the story of Harry Potter. How belt systems and CI teams can destroy inclusive practices. How leadership language invites people to the party. There are three things leaders can do to engage everyone every day: maximizing psychological safety to create environments where folks learn, contribute, and challenge the status quo.
Who might benefit? Anyone and everyone leading folks from the shop floor to top floor.
Dr. William Harvey is a seasoned Operations Leader with extensive experience in chemical processing, manufacturing, and operations management. At Michelman, he currently oversees multiple sites, leading teams in strategic planning and coaching/practicing continuous improvement. William is set to start his eighth year of teaching at the University of Cincinnati where he teaches marketing, finance, and management. William holds various certifications in change management, quality, leadership, operational excellence, team building, and DiSC, among others.
Explore our most comprehensive guide on lookback analysis at SafePaaS, covering access governance and how it can transform modern ERP audits. Browse now!
Putting the SPARK into Virtual Training.pptxCynthia Clay
This 60-minute webinar, sponsored by Adobe, was delivered for the Training Mag Network. It explored the five elements of SPARK: Storytelling, Purpose, Action, Relationships, and Kudos. Knowing how to tell a well-structured story is key to building long-term memory. Stating a clear purpose that doesn't take away from the discovery learning process is critical. Ensuring that people move from theory to practical application is imperative. Creating strong social learning is the key to commitment and engagement. Validating and affirming participants' comments is the way to create a positive learning environment.
Attending a job Interview for B1 and B2 Englsih learnersErika906060
It is a sample of an interview for a business english class for pre-intermediate and intermediate english students with emphasis on the speking ability.
Skye Residences | Extended Stay Residences Near Toronto Airportmarketingjdass
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As a business owner in Delaware, staying on top of your tax obligations is paramount, especially with the annual deadline for Delaware Franchise Tax looming on March 1. One such obligation is the annual Delaware Franchise Tax, which serves as a crucial requirement for maintaining your company’s legal standing within the state. While the prospect of handling tax matters may seem daunting, rest assured that the process can be straightforward with the right guidance. In this comprehensive guide, we’ll walk you through the steps of filing your Delaware Franchise Tax and provide insights to help you navigate the process effectively.
What is the TDS Return Filing Due Date for FY 2024-25.pdfseoforlegalpillers
It is crucial for the taxpayers to understand about the TDS Return Filing Due Date, so that they can fulfill your TDS obligations efficiently. Taxpayers can avoid penalties by sticking to the deadlines and by accurate filing of TDS. Timely filing of TDS will make sure about the availability of tax credits. You can also seek the professional guidance of experts like Legal Pillers for timely filing of the TDS Return.
Cracking the Workplace Discipline Code Main.pptxWorkforce Group
Cultivating and maintaining discipline within teams is a critical differentiator for successful organisations.
Forward-thinking leaders and business managers understand the impact that discipline has on organisational success. A disciplined workforce operates with clarity, focus, and a shared understanding of expectations, ultimately driving better results, optimising productivity, and facilitating seamless collaboration.
Although discipline is not a one-size-fits-all approach, it can help create a work environment that encourages personal growth and accountability rather than solely relying on punitive measures.
In this deck, you will learn the significance of workplace discipline for organisational success. You’ll also learn
• Four (4) workplace discipline methods you should consider
• The best and most practical approach to implementing workplace discipline.
• Three (3) key tips to maintain a disciplined workplace.
"𝑩𝑬𝑮𝑼𝑵 𝑾𝑰𝑻𝑯 𝑻𝑱 𝑰𝑺 𝑯𝑨𝑳𝑭 𝑫𝑶𝑵𝑬"
𝐓𝐉 𝐂𝐨𝐦𝐬 (𝐓𝐉 𝐂𝐨𝐦𝐦𝐮𝐧𝐢𝐜𝐚𝐭𝐢𝐨𝐧𝐬) is a professional event agency that includes experts in the event-organizing market in Vietnam, Korea, and ASEAN countries. We provide unlimited types of events from Music concerts, Fan meetings, and Culture festivals to Corporate events, Internal company events, Golf tournaments, MICE events, and Exhibitions.
𝐓𝐉 𝐂𝐨𝐦𝐬 provides unlimited package services including such as Event organizing, Event planning, Event production, Manpower, PR marketing, Design 2D/3D, VIP protocols, Interpreter agency, etc.
Sports events - Golf competitions/billiards competitions/company sports events: dynamic and challenging
⭐ 𝐅𝐞𝐚𝐭𝐮𝐫𝐞𝐝 𝐩𝐫𝐨𝐣𝐞𝐜𝐭𝐬:
➢ 2024 BAEKHYUN [Lonsdaleite] IN HO CHI MINH
➢ SUPER JUNIOR-L.S.S. THE SHOW : Th3ee Guys in HO CHI MINH
➢FreenBecky 1st Fan Meeting in Vietnam
➢CHILDREN ART EXHIBITION 2024: BEYOND BARRIERS
➢ WOW K-Music Festival 2023
➢ Winner [CROSS] Tour in HCM
➢ Super Show 9 in HCM with Super Junior
➢ HCMC - Gyeongsangbuk-do Culture and Tourism Festival
➢ Korean Vietnam Partnership - Fair with LG
➢ Korean President visits Samsung Electronics R&D Center
➢ Vietnam Food Expo with Lotte Wellfood
"𝐄𝐯𝐞𝐫𝐲 𝐞𝐯𝐞𝐧𝐭 𝐢𝐬 𝐚 𝐬𝐭𝐨𝐫𝐲, 𝐚 𝐬𝐩𝐞𝐜𝐢𝐚𝐥 𝐣𝐨𝐮𝐫𝐧𝐞𝐲. 𝐖𝐞 𝐚𝐥𝐰𝐚𝐲𝐬 𝐛𝐞𝐥𝐢𝐞𝐯𝐞 𝐭𝐡𝐚𝐭 𝐬𝐡𝐨𝐫𝐭𝐥𝐲 𝐲𝐨𝐮 𝐰𝐢𝐥𝐥 𝐛𝐞 𝐚 𝐩𝐚𝐫𝐭 𝐨𝐟 𝐨𝐮𝐫 𝐬𝐭𝐨𝐫𝐢𝐞𝐬."
Memorandum Of Association Constitution of Company.pptseri bangash
www.seribangash.com
A Memorandum of Association (MOA) is a legal document that outlines the fundamental principles and objectives upon which a company operates. It serves as the company's charter or constitution and defines the scope of its activities. Here's a detailed note on the MOA:
Contents of Memorandum of Association:
Name Clause: This clause states the name of the company, which should end with words like "Limited" or "Ltd." for a public limited company and "Private Limited" or "Pvt. Ltd." for a private limited company.
https://seribangash.com/article-of-association-is-legal-doc-of-company/
Registered Office Clause: It specifies the location where the company's registered office is situated. This office is where all official communications and notices are sent.
Objective Clause: This clause delineates the main objectives for which the company is formed. It's important to define these objectives clearly, as the company cannot undertake activities beyond those mentioned in this clause.
www.seribangash.com
Liability Clause: It outlines the extent of liability of the company's members. In the case of companies limited by shares, the liability of members is limited to the amount unpaid on their shares. For companies limited by guarantee, members' liability is limited to the amount they undertake to contribute if the company is wound up.
https://seribangash.com/promotors-is-person-conceived-formation-company/
Capital Clause: This clause specifies the authorized capital of the company, i.e., the maximum amount of share capital the company is authorized to issue. It also mentions the division of this capital into shares and their respective nominal value.
Association Clause: It simply states that the subscribers wish to form a company and agree to become members of it, in accordance with the terms of the MOA.
Importance of Memorandum of Association:
Legal Requirement: The MOA is a legal requirement for the formation of a company. It must be filed with the Registrar of Companies during the incorporation process.
Constitutional Document: It serves as the company's constitutional document, defining its scope, powers, and limitations.
Protection of Members: It protects the interests of the company's members by clearly defining the objectives and limiting their liability.
External Communication: It provides clarity to external parties, such as investors, creditors, and regulatory authorities, regarding the company's objectives and powers.
https://seribangash.com/difference-public-and-private-company-law/
Binding Authority: The company and its members are bound by the provisions of the MOA. Any action taken beyond its scope may be considered ultra vires (beyond the powers) of the company and therefore void.
Amendment of MOA:
While the MOA lays down the company's fundamental principles, it is not entirely immutable. It can be amended, but only under specific circumstances and in compliance with legal procedures. Amendments typically require shareholder
RMD24 | Retail media: hoe zet je dit in als je geen AH of Unilever bent? Heid...BBPMedia1
Grote partijen zijn al een tijdje onderweg met retail media. Ondertussen worden in dit domein ook de kansen zichtbaar voor andere spelers in de markt. Maar met die kansen ontstaan ook vragen: Zelf retail media worden of erop adverteren? In welke fase van de funnel past het en hoe integreer je het in een mediaplan? Wat is nu precies het verschil met marketplaces en Programmatic ads? In dit half uur beslechten we de dilemma's en krijg je antwoorden op wanneer het voor jou tijd is om de volgende stap te zetten.
The world of search engine optimization (SEO) is buzzing with discussions after Google confirmed that around 2,500 leaked internal documents related to its Search feature are indeed authentic. The revelation has sparked significant concerns within the SEO community. The leaked documents were initially reported by SEO experts Rand Fishkin and Mike King, igniting widespread analysis and discourse. For More Info:- https://news.arihantwebtech.com/search-disrupted-googles-leaked-documents-rock-the-seo-world/
1. INTRODUCTION
Before any dental restoration or appliance is placed in the mouth is
should be highly polished.
Not only a rough surface on restoration, denture, orthodontic
appliance and so forth uncomfortable, but also food and other debris cling
to it. Such a restoration or appliance becomes dirty and in some cases
tarnish or corrosion may occur.
Rough surface are likely to occur unavoidably during the fabrication
of an appliance.
The finished restoration has three benefits the oral health, function
and esthetics, the well contoured and polished restoration promotes oral
health by resisting the accumulation of food debris and pathologic bacteria.
This is accomplished through a reduction in total surface area and
reduced roughness of restoration surface. Another surfaces are easer to
maintain in a hygienic state when preventive home care is practiced.
Oral function is enhanced with a well polished restoration, because
food glides more freely over occlusal and embrasure surface during
mastication.
1
2. Smooth restoration contacts minimize wear rates on opposing and
adjacent teeth. This is particularly true for restorative materials such as
ceramics that contain phases that are harder than tooth enamel and dentin.
Rough material surfaces lead to the development of high contact
stresses that can cause the loss of functional and stabilizing contacts
between teeth.
Finally, esthetics demands may require the dentist to handle highly
visible surfaces of restorations differently than those that are not
accessible.
Although a high mirror like polish is preferred for previously
mentioned reasons this type of surface may not be aesthetically compatible
with adjacent teeth in highly visible areas such as labial surfaces of
maxillary anterior teeth. Fortunately, these surfaces are not subject to high
contact stresses, and they are easily accessible for cleaning.
Finishing, cutting, grinding and polishing process:
The finishing process usually removes material such that:
a) The surface finishes and imperfections are removed.
The material is shaped to an ideal form and the outermost surface of
the material is developed to a desired state.
2
3. The particles of substrate material are recovered the action of hard
material that comes into frictional contact with the substrate.
In this process the tensile and shear stress are induced within both
the substrate and abrasive instrument but for the abrasive to cut the
substrate, the stresses induced within the abrasive should not exceed the
stresses induced into the substrate. If the stress in the instrument exceeds
which developed in the substrate, than in such cases the instrument fails to
cut, grind or polish and the blade edges will become dull and abrasive will
fracture or tear away from their binder.
A cutting operation usually refers to the use of bladed instrument or
use of any instrument in a blade like fashion. The substrate may divided
into large separate pieces or may sustain large deep grooves by a cutting
operation. The cutting blades are regularly arranged. A separating wheel
can be used in a blade like a fashion.
A separating wheel does not contain individual blades but its shape
allows it to be used in a rotating blade like fashion, to slice through the
sprue and die stone materials.
A grinding operation remove small particles of a substrate through
the action of bounded or coated abrasive instrument. Each particle may
contain several sharp points that run along the substrate surface and
remove particles of the material.
3
4. These grinding instruments contain many randomly arranged
abrasive particles, because these particles are randomly arranged
innumerable unidirectional scratches are produced on material surface.
Cutting and grinding are both considered to be predominantly
unidirectional in their course of action.
A polishing operation is considered at the most refined of finishing
process, produces the finest of the particles. It acts on an extremely thin
region of the substrate surface.
The polishing is considered to be multidirectional in its course of
action. The ideally polished surface should be atomically smooth with no
surface imperfections. This condition is virtually impossible to achieve
because most restorative materials are brittle and easily acquire surface
flaws during cutting and grinding procedures.
Types of abrasives:
Abrasives can be broadly divided into natural abrasives and
manufactured abrasives.
Natural abrasives include : Arkansas stone, chalk, corundum, diamond,
Emery, garnet, pumice, quartz sand, Tripoli and zirconium silicate cuttle
and kieselguhr are derived from the remnants of living organisms.
4
5. Manufactured abrasives are synthesized materials that are generally
preferred because and their predictable physical properties.
Silicon, carbide, aluminum oxide, synthetic diamond, rough and tin
oxide are example of manufactured abrasives.
Arkansas stone:
Arkansas stone is semi translucent, light gray, siliceous sedimentary
rock mixed in Arkansas. It contains microcrystalline quartz and is dense
hard and uniformly textured. Small pieces of this material are attached to
metal shanks and trued to various shapes for fine grinding of tooth enamel
and metal alloys.
Chalks : One of the mineral forms of calcite is called chalk. Chalk is white
abrasive composed of calcium carbonate. It is used as a mild abrasive paste
to polish tooth enamel gold foil, amalgam and plastic materials.
Corundum : This mineral form of aluminum oxide is usually white, its
physical properties are inferior to those of manufactured aluminium oxide,
which has largely replaced corundum in dental applications, corundum is
used primarily for grinding metal alloys and is available as a bonded
abrasive is several shapes. It is most commonly used in an instrument
knows as a white stone.
Diamond : Diamond is transparent, colorless mineral composed of carbon.
It is the hardest substance known. Diamond is called a super abrasive,
5
6. because and its ability to abrade any other diamond abrasives are supplied
in several forms, including bonded abrasive rotary instruments, flexible
metal backed abrasive strips, and diamond polishing pastes. They are used
in ceramic and resin-based composite materials.
Emery : Thus abrasive is a grayish black corundum that is prepared in a
fine ground forms. Emery is used predominantly in the form of coated
abrasive disks and is available in a variety of grit size. It may be used for
finishing metal alloys or plastic material.
Garnet : The term garnet includes a number of different minerals that
possess similar physical properties and crystalline forms. These minerals
are the silicates of aluminium, cobalt, iron, magnesium and manganese.
The garnet abrasive used in dentistry is usually dark red. Garnet is
extremely hard and when fractured during the grinding operation, forms
sharp, chisel-shaped plates, making garnet a highly effective abrasive.
Garnet is available on coated disks and arbor bands. It is used in grinding
metal alloys and plastic materials.
Pumice : Volcanic activity produces this light gray, highly siliceous
material. It is used mainly in grit form but can be found in some rubber-
bonded abrasives. Both forms are used on plastic materials. Flour of
pumice is an extremely fine grained volcanic rock derivative from Italy and
6
7. is used in polishing tooth enamel, gold foil, dental amalgam, and acrylic
resins.
Quartz : The most commonly used form of quartz is very hard, colorless
and transparent. It is the most abundant and widespread of minerals. Quartz
crystalline particles are pulverized to form sharp, angular particles that are
useful in making coated abrasive disks. Quartz abrasives are used mostly to
finish metal alloys and may be used to grind dental enamel.
Sand : Sand is a mixture of small mineral particles predominantly
composed of silica. The particles represent a mixture of colors, making
sand abrasives distinct in appearance. Sand particles have a rounded to
angular shape. They are applied under the air pressure to remove refractory
investment materials from base metal alloy castings. They are also coated
onto paper disks for grinding of metal alloys and plastic materials.
Tripoli : This abrasive is derived from a light weight, friable siliceous
sedimentary. It can be white, gray, pink, red or yellow. The gray and red
type are most frequently used in dentistry. The rock is ground into very
fine particles and is formed with soft binders into very fine particles and is
formed with soft binders into bars of polishing compound. It is used for
polishing metal alloys and some plastic materials.
Zirconium silicate : Zircon or zirconium silicates is supplied as an off-
white mineral. This material is ground to various particle sizes and is used
7
8. to make coated abrasives disks and strips. It is frequently used as a
component of dental prophylaxis pastes.
Cuttle : Cuttle fish, cuttle bone, or cuttle are the common names for this
abrasive. It is a white, calcareous powder made from the pulverized
internal shell of a Mediterranean marine mollusk of the genus sepia. It is
available as a coated abrasive and is useful for delicate abrasion operations
such as polishing of metal margins and dental amalgam restorations.
Kieselguhr : This material is composed of the siliceous remains of minute
aquatic plants known as diatoms. The coarser form is called diatomaccous
earth, which is used as a filler in many dental materials, such as the
hydrocolloid impression materials. It is excellent mild abrasive. The risk of
respiratory silicosis caused by chronic exposures to airborne particles of
this material is significant and appropriate precautions should always be
taken.
Silicon carbide : This extremely hard abrasive was the first of the
synthetic abrasives to be made. Both green and blue black types are
produced and have equivalent physical properties. The green form is often
preferred because substrates are more visible against the green color.
Silicon carbide is extremely hard and brittle. Particles are sharp and break
to form new sharp particles. This results in highly efficient cutting of a
wide variety of materials, including metal alloys ceramics, and plastic
8
9. materials. Silicon carbide is available as an abrasive in coated disks and
vitreous bonded and rubber bonded instruments.
Aluminium oxide : Fused aluminium oxide was the second synthetic
abrasive to be developed after silicon carbide. Synthetic aluminium oxide
(alumina) is made as a white powder. It can be much harder than corundum
(neutral alumina) because of its purity. Alumina can be processed with
different properties by slight alteration of the reactants in the
manufacturing process. Several grain sizes are available and alumina has
largely replaced emery for several abrasive uses. Aluminium oxide is
widely used in dentistry. It is used to make bonded abrasives, coated
abrasives, and air-propelled grit abrasives. White stones are made of
sintered aluminium oxide and are popular for adjusting dental enamel and
for finishing both metal alloys and ceramic material.
Pink and ruby variations of aluminium oxide abrasives are made by
adding chromium compound to the original melt. Those variations are sold
in a vitreous bonded form as non-contaminating mounted stones for the
preparation of metal-ceramic alloys to receive porcelain. Any remnants of
these abrasives should not interfere with porcelain bonding to the metal
alloy. A review by Yamamoto (1985) suggested that carbide burs are the
most effective instrument for finishing this type of alloy because they do
not contaminates the metal surface with entrapped abrasive particles.
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10. Synthetic diamond abrasives : Manufactured diamond is used almost
exclusively as an abrasive and is produced at five times the level of natural
diamond abrasive. This abrasive is used in the manufacture of diamond
saws, wheels, and burs. Block with embedded diamond particles are used
to true other types of bonded abrasives. Diamond polishing pastes are also
produced from particles smaller than 5mm in diameter and are useful in
polishing ceramic materials. Synthetic diamond abrasive are used primarily
on tooth structure, ceramic materials and resin-based composite materials.
Rouge : Iron oxide is the fine, red abrasive component of rouge. It is
blended, like Tripoli, with various soft binders into a cake form. It is used
to polish high noble metal alloys.
Tin oxide : This extremely fine abrasive is used extensively as a polishing
agent for polishing teeth and metallic restorations in the mouth. It is mixed
with water, alcohol, or glycerin to form a mildly abrasive paste.
Factors influencing the efficiency of abrasives:
1. The hardness of the abrasive particles. To be effective abrasive and
polishing agents should possess certain characteristic. First of all the
cutting or abrading particle must be able to scratch or cut grooves on
the surface of the material to be treated. It must therefore be harder
than the surface against which it is to be used. It must also be
sufficiently hard to retain an effective cutting edge.
10
11. The harder the material within the particle limits the longer the agent
remains effective as an abrading agent.
2. The shape of the abrasive particles. Particles with sharp edges are
more efficient than those with abture angle.
3. The particle size of the abrasive the particle size must be enough to
remove sufficient amount of mateials.
4. Mechanical properties of the particles. Brittleness can be an
advantage. If the material breaks in the process, then it should be
able from another sharp edge.
5. The pressure applied to the abrasive. The pressure should be light,
because great pressure may fracture an abrasive cutting instrument
and also causes frictional heat.
6. Properties of the material that is being abraded.
Brittle material can be abraded rapidly where as the mollable and
ductile material (e.g. pure gold), will flow and instead of being removed
by abrasives.
7. Rate of movement. Slower the movement of the abrasive instrument
deeper will be the scratches.
The ideal abrading and polishing speeds respectively are for acrylic
resin, it is 2000 and 3000 rpm for gold alloy – 1500 rpm to 3000 rpm.
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12. During abrading polymeric materials excessive heat must be
avoided as it can cause stress relief and warpage.
Finally, the range of particle size as well as distribution and position
of the abrading particles on the holding surface plays an important role in
effectiveness of an abrasive agent.
For example if the particles are to close to each other and the debris
from the cutting can’t escape and becomes entrapped between the abrasive
particles and an it loses its effectiveness.
ABRASIVE AND EROSIVE WEAR
Abrasive wear, wear is a material removal process that can occur
whenever surfaces slide against each other. The process of finishing a
restoration involves abrasive wear through the use of hard particles.
The dentistry the outermost particles or surface material of an
abrading instrument is referred to as the abrasive. The material being
finished is called as substrate.
Substrate wear is further divided into process of two body and three
body wear. The body occurs when abrasive particles are firmly bonded to
the surface and abrasive instrument and no other abrasive particles are
used. E.g. diamond bur.
12
13. Three body wear occurs when abrasive particles are free to translate
and rotate between two surfaces.
E.g.: Dental prophylaxis, which involves the use of a rotating
rubber cup and abrasive paste on tooth or material surface.
These two process are not mutually exclusive. The diamond
particles may debond from a diamond bur and cause three body wear.
Likewise some abrasive particles in the abrasive paste can become trapped
in the surface of a rubber cup and cause two body wear.
Lubricants are often used to minimize the risk for these
unintestional shifts from the body wear and vice versa.
Erosive wear : Erosive wear is caused by hard particles impacting a
substrate surface, carried either by a sit of ream of air or liquid.
Most dental laboratories have air driven grit blasting units that
employ hard particle erosion to remove surface material. A distinction
must be made between this type of erosion and chemical erosion, which
involves chemicals such as acids and alkalis instead of hard particles to
remove substrate material.
Acid etching is a familiar term that is used, more commonly
chemical erosion, chemical erosion is not used as a method of finishing
dental materials it is used primarily to prepare surfaces to enhance
bounding or coating.
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14. Hardness of abrasive:
A stated previously the inherent strength of cutting blades or
abrasive particles on a dental instrument must be great enough is remove
particles of substrate material without becoming dull or fracturing too
rapidly. The strength of an abrasive is often measured by the hardness of its
particles or surface material to plastic deformation. The first hardness was
published by Eriedrich Mohs- A German microbiologist in 1820 the ranked
10 minerals by their relative earth resistance, mineral received a score of 1
and most scratch resistance. Mineral received the score of 10 (diamond).
The Mohs scale was later exposed in 1930s to accommodate several new
abrasive materials that received scores in a 9 to 10 range.
Knoop and Vickers hardness tests are based on indentation methods
that quantity the hardness of materials. The tip of a knoop diamond indents
had an elongated pyramid shape. Where as the Vickers diamond indenter
has an equilateral pyramid design. Both tests involve the application and
indenter to a test surface under a known load (usually 100W). The depth of
surface penetration is reported as hardness in units of force per unit area.
14
15. Hardness values for dental materials and abrasives
Material
Mohs
hardness
Knoop
Hardness
(kg/mm2
)
Vickers
hardness
(Kg/mm2
)
Diamond
Silicon carbide
Aluminium oxide
Porcelain
Pumice
Denture resins
10
9-10
9
6-7
6-7
-
7,000-10000
25,000
21,000
560
460
20
-
430
-
-
Abrasive Instrument Design
Abrasive grits – abrasive grits are derived from materials that have been
crushed and passed through a series of mesh screens to obtain different
15
16. particle size ranges. Dental abrasive grits are classified as course, medium
and superfine according to particle size ranges.
In finishing process rate of materials is not the only important
factor. The surface finish obtained with each abrasive is as important. If too
hard abrasive is used, or the grain size is too course for use on a given
material, deep acratches result in substrate that can’t be removed easily in
subsequent finishing process. Additionally. If an abrasive does not have the
proper particle shape of does not break down in a manner that creates or
exposure new sharp edges particle, it will tend to gauge the substrate.
1. Bonded abrasive : Bonded abrasive consists of abrasive particles
that are incorporated through a binder to form grinding tools such as
points, wheels, separating discs and wide variety and other abrasive
shapes. Particles are bonded by four general methods.
1. Sintering.
2. Vitreous bonding (glass or ceramic.)
3. Resinold bonding (usually phenolic resin).
4. Rubber bonding (usually silicone rubber).
Sintered abrasives are the strongest type because the abrasive
particles are fused. The vitreous bonded abrasives are mixed a glass or
ceramic matrix material, cold pressed and then are heated to cure the resin.
16
17. Rubber bonded abrasives are made in a manner similar to that for resin
bonded abrasives.
The type of bounding method employed for the abrasive greatly
affects the grinding behaviour of the tool on the substrate, bounded
abrasives that lead to disintegrate rapidly against a substrate are too weak
and result in increased abrasive costs because the reduced instrument life.
Those that tend to degrade too slowly clog with grinding debris and
result in the loss of abrasive efficiency increased heat generation and
increased finishing time. An ideal binder holds the abrasive particles in tool
sufficiently long enough to cut, grind, or polish the substrate, yet release
the either before its cutting efficiency is lost or before heat build up causes
thermal damage to the substrate. Besides are specially formulated for
substrate specific applications.
A bounded abrasive instrument should always be treed and dressed
before its use. Truing is a procedure through which the abrasive instrument
is run against a harder abrasive block until the abrasive instrument rotates
in the handpiece without accealricty or ran out when placed on substrate.
The dressing procedure like is used to shape the instrument but
accomplishes two different purposes. First dressing procedure reduces the
instrument to its correct working size and shape. Second it is used to
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18. remove clogged debris from the abrasive instrument to restore grinding
efficiency during the finishing operation.
The clogging of the abrasive instrument with debris is called
‘abrasive blinding’. Abrasive binding occurs when the debris generated
from grinding or polishing occludes the small spaces between the abrasive
particles on the tool and reduces the depth that particles can penetrate into
the substrate. As a result, abrasive efficiency is lost and greater heat is
generated.
A blinded abrasive appears to have a coating of the substrate
material on its surface. Frequent dressing of the abrasive instrument during
the finishing operation on truing instrument, maintain the efficiency of the
abrasive in removing the substrate material.
Blinders for diamond abrasive are manufactured specifically to
resist abrasive particle loss rather than no degrade at a certain point and
release particles. One reason for this is that diamond is the hardest material
known, so that diamond abrasive particles do not loose their cutting
efficacy against substrate. There is no need for new abrasive particles to be
exposed during the grinding process.
Another reason is that diamond grits are expensive and must be used
in limited quantities for instrument manufacture special bonding processes
have been designed to allow for extended instrument life by keeping the
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19. abrasive particles firmly bound to the instrument shank yet with maximum
particle exposure. Diamond particles are bonded to metal wheel and to bur
with special heat resistant resins such as polymides. The supercourse plated
with a refractory metal film such as nickel titanium nitride coatings are
used as an additional layer on some of the recent diamond abrasive
instruments to further extend their longevity.
Finishing diamond used for resin based composites contain diamond
particles 40mm or less in diameter, and many are not nickel plated.
Therefore they are highly susceptible to abuse and should always be used
with light force and copious water spray to preserve the very fine diamond
coatings.
Coated abrasive disks and strips
Coated abrasives are fabricated by securing abrasive particles to a
flexible backing material (heavy weight proper or mylar) with a suitable
adhesive material. These abrasives typically are supplied as disks and
finishing strips disks are available in different diameter and with thin and
very thin backing thickness.
Finishing and polishing for cast restoration
Finishing and polishing for cast restoration are finished and polished
using rotary instruments. The speed of the instruments (revolutions) differs
19
20. form one alloy to another, generally increasing, going from Class I to Class
IV alloys. This should be done on the die.
According to the following sequences:
1. Gross finishing
This should remove roughness impacted on the casting from the
investment mold walls, eliminate surface discolouration and eliminate
fine excess and obliterate minute defects. This step is always done
using abrasive stones and discs, ranging from sand and silicone carbide
to alumina, until no surface discrepancies are detected.
2. Removal of scratches and irregularities
This will eliminate undetected fine scratches by removing the alloy
substance between these scratches or locally melting the alloy at the
surface, obliterating these irregularities. Also, the conversion stage of
the finishing process is initiated. This step is done using wire metal
brushes, usually brass or steel, to be followed by rubber wheels and
cones. There is a large amount of heat produced in this stage, and it
may be a factor in fulfilling is objective. The alloy surface should have
a satin like surface by the end of this step.
20
21. 3. Conversion
Conversion will create the most biologically compatible surface.
This step is done using a rubber wheel or cone, followed by brushes
carrying extremely fine abrasives, such as Tripoli or specifically
compounded abrasive pastes. The alloy surface should be shiny by the
end of this stage.
4. This creates a reflective, non-adhesive surface.
It is done using rouge on a felt cone or wheel. The alloy surface
should be extremely shiny by the end of this stage. The entire oral
surface of cast alloys should be finished and polished.
FINISHING AND POLISHING THE PORCELAIN JACKET AND
CERAMIC CROWN
Porcelain adjustment kits are used for contour reduction of porcelain
restorations. These kits have a variety of stones and polishing wheels of
different abrasiveness. Since, there is some vibration produced as the rotary
instrument abrades from the surface, the porcelain crown should be
adjusted while being held between the thumb and fingers, not on the die.
A porcelain surface adjusted with disks of stones has had the surface
glaze removed. The resultant surface is rough and dull in appearance.
Restoring the polished porcelain surface is accomplished by employing one
of a variety of polishing sequences.
21
22. There may be a perforation for a polished porcelain surfaces, rather
than a highly glazed surface. Polished porcelain has a thin like surface than
in some cases simulates the surface of natural tooth structure. A highly
glazed porcelain surface at times will appear to reflective. In some patients
whose natural tooth surfaces are highly reflective, a glazed surface is,
naturally, indicated. The surface finish is a matter of careful evaluation for
each patient. From the standpoint of soft tissue compatibility, the porcelain
surfaces in the gingival crevices are best allowed to retain the natural glaze
produced by baking.
Porcelain surfaces that have been adjusted can be reglazed in a
porcelain oven, polished, by using a series of porcelain polishing
instruments, or polished using a series of rubber impregnated abrasives
followed by a creamy mix of the leviated alumina and water. More recently
specially compounded porcelain polishing pastes have gained popularity
for final polishing of a porcelain surface. Reglazing the porcelain does
require an oven, whereas the other polishing procedures can be
accomplished with rotary instruments.
In order to avoid fracture of a margin by vibration, the porcelain
jacket is polished also while being held between the fingers rather tan the
die. No matter which polishing procedure is used, it is important to follow
the recommended sequence to obtain the optimal surface finish on the
22
23. porcelain. The levigated alumina is used with a lead-center unstiched
muslin wheel on a lathe motor. A stitched wheel is undesirable since it
tends to tear the crown out of the finger grasp. Further protection of the
crown is secured by lining the polishing cubicle with dental towels. The
crown and adjacent thumb surfaces are loaded with the creamy levigated
alumina and the crown is pressed firmly against the rotating wheel, turning
the crown constantly in many directions assures the production of a good
luster. In the areas where cervical excess has been removed, a final polish
is also achieved with the lead center wheel and creamy levigated alumina.
The wheel should turn away from the cervical margin, not into it. This is
sequence with the lead center wheel is completed in 3 to 4 minutes.
Polishing material is removed by scrubbing the crown with a soft bristled
tooth brush under a stream of water. All moisture is removed with
compressed air. The crown is cleansed with alcohol, redried and the tested
in the patient’s mouth. The patient is asked to wet the anterior teeth,
including the crown, with saliva. An evaluation of the finish can now be
made by the patient and the operator. If a high reflective luster is desired,
the crown is returned to the laboratory and polished with a creamy mix of
tin oxide. This tends to add even further highlight effect to the porcelain
surface.
23
24. CONTENTS
Introduction
Finishing, Cutting, Grinding and Polishing Process
Factors Influencing the Efficiency of Abrasives
Hardness of Abrasive
Abrasive Instrument Design
Finishing and Polishing of Cast Restoration
Finishing and Polishing of the Porcelain Jacket and Ceramic
Crown
References
24