Dental Materials in the Digital Age PowerPoint

DENTAL MATERIALS IN THE DIGITAL AGE DR. ÖĞR. ÜYESİ BEGÜM ASL AN  Computer-aided design- computer-aided manufacturing (CAD-CAM) technologies were introduced to dentistry about 50 years ago. Today, many CAD-CAM systems and workflows are available to produce highly accurate dental...

DENTAL MATERIALS IN THE DIGITAL AGE DR. ÖĞR. ÜYESİ BEGÜM ASL AN  Computer-aided design- computer-aided manufacturing (CAD-CAM) technologies were introduced to dentistry about 50 years ago. Today, many CAD-CAM systems and workflows are available to produce highly accurate dental prostheses at low cost. MATERIALS USED IN CAD-CAM SYSTEMS: Ceramics Polymers Metals CE RAMICS C E RA M I C S Ceramics are hard, stable and strong, but brittle under stress. This brittleness of ceramics can be overcome by supporting the ceramic with a high-strength core material or by selecting a ceramic with increased strength or bending resistance.  C E RA M I C S Dental ceramics can be crystalline or non- crystalline materials or a combination of them. There are three main types according to their microstructure: (i) Glassy ceramics (leucite, feldspathic ) (ii) partially crystalline glass ceramics (lithium disilicate ) or C E RA M I C S Ceramics with mostly glassy microstructure, such as leucite and feldspathic-based glasses, are more aesthetic but have the lowest mechanical properties and are often used as veneer materials.  C E RA M I C S Ceramics with more crystalline phase such as zirconia and alumina are stronger, but not as aesthetically successful. The strength and aesthetic properties of partially crystalline glassy ceramics such as lithium disilicate fall between glassy and polycrystalline ceramics  COMMON PROCESSING METHODS Machinable and pressable CAD‐CAM materials developed for ceramic restoration are industrially manufactured and are almost defect‐free before use but each method of making them introduces different types of flaws.  COMMON PROCESSING METHODS For instance, pressing ceramic materials can lead to porosity , while grinding them can cause cracks and surface defects that reduce the strength of the restoration COMMON PROCESSING METHODS Milling of fully sintered ceramics , which are very hard, commonly leads to formation of cracks and chipping ending up with a reduced quality of the final restoration.  COMMON PROCESSING METHODS For this reason, machining (milling) of ceramics in a partially sintered or pre-crystalline state called ‘green phase’ is more commonly preferred. COMMON PROCESSING METHODS After milling, restorations in the green phase undergo crystallization or sintering heat treatment processes to complete the sintering and the mechanical properties of the restoration are improved. P O LYME RS  P O LY M E R S 📌 Polymers are lightweight, ductile and have lower strength compared to most metals and ceramics. 📌 However, their aesthetics and ease of repair make them a useful material for many dental applications.  P O LY M E R S Since high functional loads are encountered in the oral environment, traditional polymers used for fixed prostheses may need to be reinforced or supported with a stronger material.  P O LY M E R S For full-mouth reconstructions polyether ether ketone poly-aryl-ether ketone polyether aryl ketone and new, high-performance polymeric materials containing polyether ketones have been developed. P O LY M E R S High-performance materials are often used as a supporting frame and require a covering material to mask the color. ME TAL AL LOYS  M E TA L A L L OY S 📌 Metals used in dentistry are often an alloy or a combination of two or more metals, resulting in materials with improved properties. 📌 Typical properties of metals include high strength, polishability, and opacity.  M E TA L A L L OY S 📌 Dentistry's greatest challenge when using metals involves hiding them from view by layering with polymers or ceramics. COMMON PROCESSING METHODS 📌 Historically, restorative metals were produced by casting, forging or sintering, but today most CAD- CAM workflows are either additive or subtractive. 📌 Cobalt-chromium and titanium alloys are some of the commonly used base metal alloys COMMON PROCESSING METHODS 📌 The scientific literature does not support CAD‐CAM milling technology over classical laboratory procedures for fabricating a metal restoration and both workflows can result in clinically acceptable restorations.  GENEL İŞLEME YÖ N T E M L E R I 📌 The innovations in AM (Additive manufacturing) CAD-CAM workflows have enabled the production of complex shapes using selective laser melting and electron beam melting. 📌 The biggest disadvantage of AM may be the cost of initial equipment acquisition.  CASE SELECTION The reasons for considering a material to be used in a prosthetic reconstruction may be; 📌 Esthetics, 📌 Expected forces 📌 Mechanical properties, 📌 Available space, 📌 Wear resistance 📌 Survival rate  ESTHETICS Translucency is a function of a material's light transmission, a b s o r p t i o n and re fl e c t i v i t y. Core materials affect the translucency of the restoration, especially in the gingival 1/3.  ESTHETICS Polycrystalline ceramic materials such as alumina and zirconium do not transmit light. Glass ceramics and zirconium partially stabilized with 4 and 5 mol% yttria fall between glassy and polycrystalline materials and easily transmit visible light  ANTICIPATED STRESS OR FORCE The magnitude of forces on teeth and restorations is individualized and depends on the patient's personal habits. It is also influenced by the direction of the force, the prosthetic design and the type of restoration. ANTICIPATED STRESS OR FORCE Conventional polymeric dental materials such as acrylics and urethanes cannot withstand high functional forces without support from a high-strength framework. Depending on the severity of occlusal forces and parafunctional movements, even supporting polymers with ANTICIPATED STRESS OR FORCE New h i g h - p e r f o r m a n c e p o l y m e r s are often produced using high heat and pressure with reliable industrial production methods; these materials have high flexural strength and can be used in m i l l i n g machines to produce complex shapes. ANTICIPATED STRESS OR FORCE Precious metal-based dental alloys can be 3D printed or milled; however, a base metal alloy such as chromium-cobalt or titanium are usually chosen. ANTICIPATED STRESS OR FORCE Glass ceramics have exceptional aesthetics and can be m i l l e d or p r e s s e d. They have moderate durability and are often used for single tooth restorations or short, fixed dentures. Intraorally, the time from load to fracture is increased by dental bonding technology. ANTICIPATED STRESS OR FORCE Polycrystalline ceramics alumina and zirconia are l e s s e s t h e t i c but have sufficient strength to be used as a monolithic structure. Aesthetics are achieved by applying superficial or intrinsic colorants with polycrystalline materials. Alternatively, polycrystalline materials can be layered or coated with a more aesthetic “g l a s s o r g l a s s c e r a m i c ”. ANTICIPATED STRESS OR FORCE Polycrystalline ceramics have the highest flexural strength of any ceramic material available, and short-term clinical evaluations show that clinical success can be expected if the minimum recommendations are followed. SOFT ‘MILLING ’ Although the use of For milling hard lubricant/coolant during materials such as milling helps to reduce glass-ceramics, surface stress, machine- induced superficial diamond-coated milling microcracks may occur tools with higher RPM during the processing of are usually used. glass-ceramic restorations due to the brittleness of the material. SOFT ‘MILLING ’ In lithium disilicate To overcome this glass ceramic milling, limitation, instead of ' f u l l y soft milling c r y s t a l l i z e d ' blocks, s t r a t e g y is often used softer ' p r e - for high-strength ceramic c r y s t a l l i z e d ' blocks are restorations. used. SOFT ‘MILLING ’ Once the restorations have been successfully milled to the desired shape, they undergo h e a t t re a t me n t. SOFT ‘MILLING ’ SOFT ‘MILLING ’ Most zirconia blocks available on the market are milled in a pre- sintered state that is very soft, often referred to as the g r e e n state.  SOFT ‘MILLING ’ The sintering of z i r c o n i a causes dimensional change. To compensate for this sintering shrinkage, zirconia restorations are milled l a r g e r than their actual size, then the material is restored to its actual size by volume shrinkage throughout the sintering process. “Pre‐sintered zirconia restoration (left): the restoration is approximately 20% larger than the final restoration” COMPOSITE RESIN & HYBRID RESIN CERAMIC The m e c h a n i c a l p r o p e r t i e s (flexural resistance, resilience) of the resin-infiltrated ceramic material, called h y b r i d c e r a m i c , are between those of composite resin and reinforced glass ceramic. COMPOSITE RESIN & HYBRID RESIN CERAMIC The probability of m a r g i n a l f r a c t u r e s occurring during milling is signifi cantly lower compared to dental ceramic blocks of similar strength. COMPOSITE RESIN & HYBRID RESIN CERAMIC Composite or hybrid resin ceramic blocks are mostly used for p a r t i a l coverage CAD/CAM composite resin inla restorations. T H A N K YO U..