Inlays and Onlays Ceramics 2022

Indirect Tooth-Colored Restorations •Introduction •Indications and contraindications •Advantages and Disadvantages •Clinical procedures : INLAYS AND ONLAYS •Difference between ceramic and cast metal inlays and onlays •Impression•Tr y- i n and cementation •Finishing and...

Indirect Tooth-Colored Restorations •Introduction •Indications and contraindications •Advantages and Disadvantages •Clinical procedures : INLAYS AND ONLAYS •Difference between ceramic and cast metal inlays and onlays •Impression•Tr y- i n and cementation •Finishing and polishing •Inlays and onlays using Different ceramic systems •Common problems and •solutions •Repair of ceramic inlays and onlays •ConclusionCONTENTS Types of Ceramic Inlays and Onlays •Feldspathic Porcelain (feldspar, silica, alumina) •Lithium Disilicate (EMAX Press or CAD) •Zirconia •Resin Composite (ENAMIC) INDICATIONS1. SMALL TO MODERATE CARIOUS LESIONS 2. LARGE CARIOUS OR TRAUMATIC LESIONS 3. ENDODONTICALLY COMPROMISED TEETH 4. TEETH WHERE IT IS DIFFICULT TO DEVELOP RETENTION FORM 5. WHEN METAL ALLERGY IS A FACTOR 6. THE RESTORATIONS OF TEETH IN AN ARCH OPPOSED BY ALREADY PRESENT CERAMIC RESTORATIONSESTHETICS INTRODUCTION•Dental ceramics are nonmetallic, inorganic structures, primarily containing compounds of oxygen with one or more metallic or semi-metallic elements (aluminum, boron, calcium, cerium, lithium, magnesium, phosphorus, potassium, silicon, sodium, titanium, and zirconium). •Ceramic inlays offer an aesthetic alternative to metal class I or II restorations. Their primary use is in compromised posterior teeth with intact buccal and lingual walls. These restorations offer the opportunity to conserve tooth structure while taking advantage of the mechanical benefits of modern adhesive technology, which can strengthen the compromised tooth •According to Sturdevant, an onlay caps all cusps; an inlay may cap none or may cap all but one cusp. CONTRAINDICATIONS•Parafunctional habits •Heavy occlusal forces •Deep subgingival preparations •Aggressive wear of dentition •Although technique-sensitivity is itself not a contraindication, difficulty to maintain a dry operative field and obtaining precisely fabricated restorations, with attention to detail in placement, can make this contraindication a reality. ADV A NTAGES •Improved physical properties •Va r i e t y of materials and techniques •Wear resistance •Reduced polymerization shrinkage •Support of remaining tooth structure •More precise control of contours and contacts •Biocompatibility and good tissue response •Increased auxiliary support DISAD V ANTAGES •Increased cost and time •Te c h n i q u e sensitivity •Difficult try-in and delivery •Brittleness of ceramics •Wear of opposing dentition and restorations •Short clinical track record •Low potential for repair TOOTH PREPARATION •The principles of cavity preparation for esthetic inlays or onlays differ from those for gold restorations. •For esthetic inlay or Onlay restorations bevels and retention forms are not needed . •Resistance form is generally not necessary but may be required in very large onlay restorations. •Retention form is not as critical due to the bonded nature of the restoration, and bevels are contraindicated. RULE FOR CUSP CAPPING •If cusps must be capped, they should be reduced 1.5 to 2 mm and should have a 90-degree cavosurface angle. •When capping cusps, especially centric holding cusps, it may be necessary to prepare a shoulder to move the facial or lingual cavosurface margin away from any possible contact with the opposing tooth, either in maximum intercuspal position or during functional movements. •Such contacts directly on margins can lead to premature deterioration of marginal integrity. • The axial wall of the resulting shoulder should be sufficiently deep to allow for adequate thickness of the restorative material and should have the same path of draw as the main portion of the preparation •For onlay restorations, nonworking and working cusps are covered with at least 1.5 mm and 2 mm of material, respectively. •If the cusp to be onlayed shows in the patient’s smile, a more esthetic blended margin is achieved by a further 1 to 2-mm reduction with a 1 mm chamfer IMPRESSION•To o t h - c o l o r e d i n l a y o r o n l a y systems require an elastomeric (PVS) or optical impression of the prepared tooth and the adjacent teeth and interocclusal records, which allow the restoration to be fabricated on a working cast in the laboratory. •With chairside CAD/CAM systems, no working cast is necessary. PROVISIONAL RESTORATION For exceptionally non-retentive preparations, or when the temporary phase is expected to last longer than 2 to 3 weeks, zinc phosphate or polycarboxylate cement can be used to increase retention of the provisional restoration. •Resin-based temporary cements are also available (e.g., Te m p B o n d Clear ) •Provisional can be made using conventional techniques and bis-acryl composite materials. (ej Protemp ) TRY-IN AND CEMENTATION •Try-in and bonding of tooth-colored inlays or onlays are more demanding than those for cast gold restorations because of (1) the relatively fragile nature of some ceramic materials (2) the requirement of near-perfect moisture control (3) the use of resin cement. •Occlusal evaluation and adjustment generally are delayed until after the restoration is bonded. to avoid fracture of the ceramic material TRY-IN PRELIMINARY STEPS•The use of a rubber dam is strongly recommended to prevent moisture contamination of the conditioned tooth or restoration surfaces during cementation and to improve access and visibility during delivery of the restoration. •After removing the provisional restoration, all of the temporary cement is cleaned from the preparation walls. RESTORATION TRY-IN AND PROXIMAL CONTACT ADJUSTMENT •Passing thin dental floss through the contact reveals tightness and position of the proximal contact, signifying to the experienced operator the degree and location of excess contact. •Articulating paper also can be used successfully to identify overly tight proximal contacts. •Abrasive disks or points are used to adjust the proximal contour and contact relationship. •While adjusting the intensity and location of the proximal contacts, increasingly finer grits of abrasive instruments are used to polish the proximal surfaces because they will be inaccessible for polishing after cementation. •Marginal fit is verified after the restoration is completely seated. •Ceramic inlays and onlays typically have slightly larger marginal gaps than comparable gold restorations. •Slight excesses of contour can be removed, if access allows, using fine-grit diamond instruments or 30-fluted carbide finishing burs. These adjustments are done preferably after the restoration is bonded so that marginal fractures are avoided. RESTORATION TRY-IN AND PROXIMAL CONTACT ADJUSTMENT MECHANISM OF BONDING •Bonding of ceramic CAD/CAM restorations is a critical step in achieving good long-term results. •Ceramic restorations are bonded to tooth structure by (1)Etching enamel to increase the bondable surface area (2)Etching, priming, and applying the bonding agent to dentin (when appropriate) (3)Etching ( by hydrofluoric acid ) and then priming (silanating ) the restoration (4)Cementing the restoration with composite cement •Ceramic restorations must be etched internally with 6% to 10% hydrofluoric acid for 1 to 2 minutes to create retentive microporosities analogous to those that occur in enamel on etching with phosphoric acid. •Hydrofluoric acid must be rinsed off carefully with running water for at least 2 minutes. •Sandblasting with aluminum oxide particle can be done in the internal surface of the restoration. •Mean bond strengths decrease, however, when hydrofluoric acid etching is not used. Hydrofluoric acid •The bonding of traditional glass-containing ceramics or silica based ceramics utilizes mechanical and adhesive way •Mechanical bonding assumed micromechanical interlocking between the resin cement and roughen surface of silica-based ceramics. •Hydrofluoric acid etching is the method commonly used for roughening the silica-based ceramics surfaces •Chemical adhesion of glass ceramic and resin cements is achieved with use of bi-functional compounds, silanes that promote connection between dissimilar organic and inorganic counterparts. •Also, silanes could influence increasing surface energy and wettabiliy of ceramic surfaces, which enhances both mechanical and chemical bonding ACID ETCHING •Acid etching with solutions of hydrofluoric acid (HF) or ammonium bifluoride can achieve proper surface texture and roughness. •The glassy matrix is selectively removed, and crystalline structures are exposed. •HF solutions between 2.5% and 10% applied for 2 to 3 minutes seem to be most successful •The well known methods of mechanical and chemical bonding used on glass- ceramics are not applicable for use with zirconia . •The most important reason for this is the absence of silica in the zirconia microstructure which ignores the viability of etching as a roughening method essential for mechanical bonding, as well as nullified the use of silanes, forming surfaces hydroxyls and developing the chemical bond DIFFERENT APPROCHES IN ZIRCONIA/CEMENT BONDING •Surface abrasion or roughening (sandblasting) •Application of MDP ➢Nanostructured alumina coating •Surface treatments : Hot chemical etching solution, Laser application, Zirconia ceramic powder coating, Application of phosphate ester primers and phosphate modified resin cements, Gas-phase fluorination process 10-Methacryloyloxydecyl dihydrogen phosphateMDP CERAMIC BONDING FOR RESTORATIONS FABRICATED IN OFFICE CERAMIC BONDING FOR RESTORATIONS FABRICATED IN EXTERNAL LABORATORY CEMENTATION•The preparation surfaces are etched and treated with the components of an appropriate enamel/ dentin bonding system •Ty p i c a l l y, the final step of the bonding system (e.g., an unfilled resin) also is applied to the internal surfaces of the restoration previously etched and silanated. (Self-adhesive, resin based cements have been introduced in recent years, but whether they are appropriate with tooth-colored inlays/onlays remains unproven.) • A d u a l - c u r e c o m p o s i t e c e m e n t i s m i x e d a n d i n s e r t e d i n t o t h e p r e p a r a t i o n with a paddle-shaped instrument or a syringe. •The internal surfaces of the restoration also are coated with the composite cement , and the inlay is immediately inserted into the prepared tooth, using light pressure. •A b a l l b u r n i s h e r a p p l i e d with a slight vibrating motion is usually sufficient to seat the restoration •Excess composite cement is removed with thin-bladed composite instruments, brushes, or an explorer 1.Resin-based composites are the material of choice for adhesive luting. Both material properties and wear behavior of fine particle hybrid-type resin-based composites are superior to other materials. The use of compomers is questionable due to hygroscopic expansion and possible crack formation as proven for IPS Empress caps in vitro and in vivo. 2.Recent luting cements exhibit excellent flow characteristics with mean film thicknesses ranging between 8 microm and 21 microm. The ultrasonic insertion technique is recommended for viscous luting composites or conventional restorative composites utilizing their thixotropic properties. CEMENTATION RECOMMENDATIONS 3. For successful overhang control, good fit of the restoration (during luting) and high radiopacity of the cement (after luting) are indispensable. Overhang control is estimated easier when the ultrasonic insertion technique is applied . 4. The pre-treatments of ceramic inlays using hydrofluoric acid or silica coating result in effective bonding; for pre-treatment of resin-based composite inlays, silica coating is promising as well. 5. Bonding to enamel and dentin is proven clinically acceptable, but it should be performed with multi-step systems providing separate primers and bonding agents producing a perfect internal seal with almost no hypersensitivities. Dual-cured multi-step bonding agents provide the most promising potential. 7. The viscosity and filler content of the resin composite used for luting does not influence the wear characteristics within the marginal luting area in vivo. However, the ultrasonic insertion technique involving high viscosity materials provides enhanced handling characteristics for luting of tooth- colored inlays. 8. Clinical results with tooth-colored inlays and veneers are promising over periods of up to 10 yrs, including use in severely destroyed teeth. FINISHING AND POLISHING PROCEDURES•After light-curing the cement, the plastic matrix strips and the wedges (if used) are removed, and the setting of the resin cement is verified. •All marginal areas are checked with an explorer After tooth preparation, an impression is made, and a “master” working cast is poured of die stone 1.The die is duplicated and poured with a refractory investment capable of withstanding porcelain-firing temperatures. The duplication method must result in the master die and the refractory die being accurately interchangeable 2. Porcelain is added into the preparation area of the refractory die and fired in an oven. Multiple increments and firings are necessary to compensate for sintering shrinkage 3. The ceramic restoration is recovered from the refractory die, cleaned of all investment, and seated on the master die and working cast for final adjustments and finishing FELDSPATHIC PORCELAIN INLAYS AND ONLAYS FELDSPATHIC PORCELAIN INLAYS AND ONLAYS Advantages : Low startup cost. •The ceramic powders and investments are relatively inexpensive, and the technique is compatible with most existing ceramic laboratory equipment such as firing furnaces. Disadvantages : technique sensitivity, both for the technician and the dentist. •Inlays and onlays fabricated with this technique must be handled gently during try-in and bonding to avoid fracture. • Feldspathic porcelains are weak, so even after bonding, the incidence of fracture can be relatively high PRESSED GLASS-CERAMICS•In 1984, the glass-ceramic material Dicor (DENTSPLY International, Yo r k , PA ) was patented and became a popular ceramic for dental restorations. A m a j o r d i s a d v a n t a g e o f Dicor was its translucency, which necessitated external application of all shading •Dicor restorations were made using a lost-wax, centrifugal casting process. Newer leucite-reinforced glass-ceramic systems (e.g., IPS Empress, Ivoclar Vivadent, Amherst, NY) also use the lost-wax method, but the material is heated to a high temperature and pneumatically pressed, rather than centrifuged, into a mold PRESSED GLASS-CERAMICS •After tooth preparation, an impression is made, and a working cast is poured in die- stone. A w a x p a t t e r n o f t h e r e s t o r a t i o n i s m a d e u s i n g c o n v e n t i o n a l techniques •After spruing, investing, and wax pattern burnout, a shaded ceramic ingot and aluminum oxide plunger are placed into a special furnace •The shade and opacity of the selected ingot are based on the information provided by the clinician, specifically the desired shade of the final restoration and the shade of the prepared tooth. •At approximately 2012°F (1100°C), the ceramic ingot becomes plastic and is slowly pressed into the mold by an automated mechanism. •After being separated from the mold, the restoration is seated on the master die and working cast for final adjustments and finishing. •To reproduce the tooth shade accurately, a heavily pigmented surface stain is typically applied. •The ceramic ingots are relatively translucent and available in a variety of shades, so staining for hot pressed ceramic inlay and onlay restorations is typically minimal. PRESSED GLASS-CERAMICS •The advantages of leucite-reinforced pressed ceramics are their (1)similarity to traditional “wax-up” processes (2)excellent marginal fit (3)moderately high strength (4)surface hardness similar to that of enamel. Although pressed ceramic inlays and onlays are stronger than porcelain inlays made on refractory dies, they are still somewhat fragile during try-in and must be bonded rather than conventionally cemented. LITHIUM DISILICATE •Lithium disilicate (e.max, Ivoclar Vivadent Inc., Amherst, NY), is available in both pressed (IPS e.max Press) and machinable (IPS e.max CAD) forms, and either can be used to fabricate inlays and onlays. •The two forms of e.max are slightly different in composition, but lithium disilicate is a moderately high-strength glass ceramic that also can be used for full crowns or ultra-thin veneers. •In vitro testing of this ceramic material has shown very positive results, and it has become a highly popular alternative for inlays and onlays. •However, because the material is relatively new, long-term clinical studies to demonstrate superior performance are lacking. COMPUTER-AIDED DESIGN/COMPUTER- ASSISTED MANUFACTURING INLAYS AND ONLAYS •Generation of a chairside CAD/CAM restoration begins after the dentist prepares the tooth and uses a scanning device to collect information about the shape of the preparation and its relationship with the surrounding structures •This step is termed optical impression. •The system projects an image of the preparation and surrounding structures on a monitor, allowing the dentist or the auxiliary personnel to use the CAD portion of the system to design the restoration. •The operator must input or confirm some of the restoration design such as the position of the gingival margins •After the restoration has been designed, the computer directs a milling device (CAM portion of the system) that mills the restoration out of a block of high-quality ceramic or composite in minutes •The restoration is removed from the milling device and is ready for try-in, any needed adjustment, bonding, and polishing •Several different types of ceramics are available for chairside CAD/CAM restoration fabrication. •These include the feldspathic glass ceramics Vitablocs Mark II (Vident, Brea, CA) and CEREC Blocs (Sirona, manufactured by Vita Zahnfabrik, Bad Säckingen, Germany). •The ceramic blocks are available in various shades and opacities, and some are even layered to mimic the relative opacity or translucency in different areas of a tooth. •Tw o leucite-reinforced glass ceramics are available—IPS Empress CAD (Ivoclar Vivadent) and Paradigm C (3M ESPE). •Lithium disilicate also is available in machinable form as IPS e.max CAD blocks. Although newer materials are stronger than the original ceramics, less is known about their long-term clinical performance CERAMIC RECONSTRUCTION SYSTEM (CEREC-1) •The Ceramic Reconstruction System (CEREC-1; Siemens, Germany) was the first commercially available CAD/CAM system used in dentistry. •An intraoral video camera images the tooth preparation and the adjacent tooth surfaces. •Elevations of the imaged surfaces are calculated by Moiré fringe displacement. •Features of the tooth preparation are used to define the limits of the restoration. •External surfaces of the restoration are estimated as distances to adjacent tooth structure in the computer view. •Occlusal surfaces are designed from a preexisting shape library and information about the occlusion. • CEREC-3 displays an extremely high level of sophistication and can fabricate inlays, onlays, crowns, and veneers. •It can be operated chairside, but also is being used with remote milling units in dental laboratories for two-appointment procedures. •All other current CAD/CAM systems are employed in dental laboratories to fabricate a wide range of ceramic restorations CEREC AC (A) and E4D (B) computer - aided design/ computer -assisted manufacturing (CAD/CAM) devices. These chairside units are compact and mobile COMMON PROBLEMS AND SOLUTIONS •The most common cause of failure of tooth-colored inlays/onlays is bulk fracture. •Bulk fracture can result from placing the restoration in a tooth where it should not have been indicated, such as in bruxers and clenchers, or from lack of appropriate restoration thickness derived from lack of tooth preparation. •If bulk fracture occurs, replacement of the restoration is almost always indicated. REPAIR OF CERAMIC INLAYS AND ONLAYS •Before initiating any repair procedure, the operator should determine whether replacement rather than repair is the appropriate treatment •A small fracture resulting from occlusal trauma might indicate that some adjustment of the opposing occlusion is required. •The repair procedure is initiated by mechanical roughening of the involved surface. Although a coarse diamond may be used, a better result is obtained with the use of air abrading or grit blasting with aluminum oxide particles and a special intraoral device •For ceramic restorations, the initial mechanical roughening is followed by brief (typically 2 minutes ) application of 10% hydrofluoric acid gel . •Hydrofluoric acid etches the surface, creating further microdefects to facilitate mechanical bonding •The next step in the repair procedure is application of a silane coupling agent . •Silanes mediate chemical bonding between ceramics and resins and may improve the predictability of resin-resin. •After the silane has been applied, a resin adhesive is applied and light cured. •A composite of the appropriate shade is placed, cured, contoured, and polished GRACIAS