DT Israel

11 Dentaltribune israel edition‫טכנולוגיה‬ Dr Kenneth Malament USA Posterior restorations are among the most frequently performed treatments in dentistry today, yet various challenges and limitations still exist in their execution. Whether for cases involving full coverage, partial, implant-supported, or aesthetic restorations, the process of selecting the appropriate material for indirect posterior treatments can be wrought with confusing information because the requisite demands may seem contradictory. Among the considerations for posterior restorations are establishing proper isolation for adhesive cementation, ensuring facture resistance of the selected material for long-term function, and achieving proper anatomical form and marginal integrity. 1–3 Superior fit contributes to the best possible outcome and functional longevity for the patient,3 while strength of the selected restorative material helps to ensure resistance against the masticatory force exerted on posterior dentition. Combined, ideal anatomic form, marginal adaptation, and appropriate proximal contact and contour are required of materials and resulting restorations used in posterior treatments. 4, 5 Additionally, aesthetics in posterior restorations has become an increasingly important consideration for both patient and clinician despite their location in less visible areas of the mouth. Shade and color matching between the restorative material and natural tooth structure is necessary for creating lifelike restorations.6 Not surprisingly, considering the multiple requirements for posterior restorations, it can be challenging for clinicians to determine the most appropriate material for various indications.7 High-strength allceramic materials are recommended for posterior restorationsbasedontheirstrength. However, some have lacked aesthetics.8 Recently, non- ceramic materials have evolved to compete with ceramic in posterior restorations. The numerous indirect resin composites now available may perform well in certain clinical situations, but they still require further research to determine whether they are viable for long-term success. 9, 10 The advent of new materials and the expanding use of CAD/CAM have ushered in improvements in ceramic materials. The result has been increased use of durable metal free materials that are more aesthetic for successful treatments.11 Investment in terms of education, purchasing of the systems, and skills enhancement is required for proper and predictable use. Among these advancements is lithium disilicate (IPS e.max CAD/Press, Ivoclar Vivadent), a universal all-ceramic material for indirect restorations. Because this material combines strength with high aesthetics,12 its durability, predictability, and longevity make it an ideal material forindirectposteriorrestorations.13 Lithium disilicate Lithium disilicate (e.max) is categorised as a glass-based ceramic. It is generally composed of quartz, lithium dioxide, phosphorus oxide, alumina, potassium oxide, and other components.14 These powders are combined to make a glass melt that is moulded and then formed into blocks or ingots. The manufacturing process creates a highly thermal shock- resistant glass-ceramic due to the low thermal expansion that results during manufacturing.15 Within the material, needle-like crystals form and comprise about two-thirds of the volume.16 The ingots can be processed using the lost-wax hot pressing technique, whereas blocks are milled using the CAD/CAM technique. Lithium disilicate can be cemented using adhesive bonding (such as Multilink N/ Automix, Ivoclar Vivadent) or conventional cementation techniques.8 The monolithic property of e.max contributes to the strength and aesthetics of the restoration. The traditional use of a highstrength core material made of zirconia or alumina decreased aesthetics owing to the high value and increased opacity compared with glass-ceramic materials. Even though these high-strength core materials demonstrated excellent mechanical properties, the added layers of veneered ceramic, which have a much lower strength, caused the overall strength of the restoration to decrease.16 Lithium disilicate circumvents these problems and offers both strength and high aesthetics for an expanded range of indications other ceramics, e.max offers 360 MPa in strength, which is over twice the strength of other Understanding e.max as the ideal material for indirect posterior and anterior restoration Fig. 1a: The patient presented with three non-vital teeth.—Fig. 1b: The situation at the five-year recall appointment: the three anterior crowns were completed to improve aesthetics and longevity.— Fig. 2a: A patient presented with failing ceramic veneers..—Fig. 2b: The teeth were prepared for full-coverage restorations owing to significant decay.—Fig. 2c: Four lithium disilicate restorations were placed to provide the desired aesthetics for the patient.—Fig. 3a: The patient presented with worn dentition, a closed vertical dimension of occlusion, and poor occlusion on the left side.— Figs. 3b: The teeth were prepared for full-coverage restorations.—Fig. 3c: All of the maxillary teeth were crowned with lithium disilicate restorations to achieve a good occlusion and great aesthetics. —Figs. 4a & b: A patient presented with mesial decay on a maxillary molar.—Fig. 4c: A mesial–occlusal inlay fabricated from lithium disilicate was adhesively bonded into place along the enamel margins.—Figs. 5a & b: The patient presented with significant mesial–occlusal decay.—Fig. 5c: A mesial–occlusal lithium disilicate onlay was adhesively bonded into place along the enamel margins. —Figs. 6a–c: A stock titanium abutment with Laser-Lok was used for waxing and pressing a lithium disilicate implant abutment.—Figs. 6d–f: The pressed lithium disilicate restoration was cemented to the titanium abutment.—Figs. 6g & h: The lithium disilicate restoration was cemented to the titanium abutment in the mouth.