DT Israel

10Dentaltribune israel edition ‫טכנולוגיה‬ ceramics.13, 14, 16 Another advantage is that e.max can be finished thinner without chipping owing to its higher edge strength.13–15 Additionally, e.max provides exceptional aesthetics without requiring a veneering ceramic when processed in its monolithic form. This allows restorations to maintain their structural ntegrity.7 The material is available in four translucencies, including high opacity, medium opacity, low translucency, and high translucency.15 In a five-year study conducted by Ivoclar Vivadent, 97 per cent of the pressed e.max restorations studied received an excellent rating in aesthetics.17 Research continues to examine the efficacy of lithium disilicate restorations. Fasbinder et al., for example, investigated the longevity of lithium disilicate crowns, following 62 restorations over two years. The researchers found no identified cases of crown fracture or surface chipping. Over the two-year period, the patients were checked three times and none reported any sign of sensitivity.11 Guess et al. examined the fatigue behaviour and reliability of CAD/ CAM-processed lithium disilicate compared with zirconia all- ceramic crowns veneered using the hand-layering technique. They concluded that the lithium disilicate configurations resulted in fatigue-resistant crowns compared with the zirconia crowns, which demonstrated a high susceptibility to early veneer failure.18 Further, e.max can be used for a variety of indications, as demonstrated by Sorensen et al., in whosestudye.maxwasusedforthe fabrication of three-unit bridges. The researchers concluded that by using e.max they achieved an acceptable clinical success rate.19 Other indications include posterior partial and full-coverage, as well as implant-supported restorations. 20 Case studies IPS e.max can be used for a wide range of universal anterior and posterior indications. Patients with concerns regarding aesthetics are pleased after receiving their restorations, and clinicians can be assured of functional predictability. Pos terior restorations fabricated from e.max demonstrate the requisite strength, aesthetics, and durability. Whether full or partial coverage, e.max restorations provide function and fit to ensure satisfaction of both clinician and patient. The following cases demonstrate the material’s versatility for a number of everyday restorative cases. Case 1 The patient presented with three non-vital maxillary anterior teeth and had concerns regarding her aesthetics (Fig. 1a). Three anterior full-coverage all-ceramic restorations were fabricated from e.max in order to enhance aesthetics and function, and were cemented with Multilink N adhesive cement (Fig. 1b). Case 2 A patient presented with failing ceramic veneers in the maxillary anteriorregionandconcernsabout the aesthetics of her smile (Fig. 2a). Owing to significant tooth decay, the teeth were prepared for full coverage restorations (Fig. 2b). Four e.max restorations were fabricated to establish an enhanced aesthetic appearance for the patient and cemented with Variolink N adhesive cement (Fig. 2c). The lithium disilicate material absorbs and reflects light in a similar manner to natural teeth. The wide variety of options for brightening the restorations enabled the clinician to meet the patient’s expectations. Case 3 A female patient presented with worn dentition, a closed vertical dimension of occlusion, and poor occlusion, particularly on the left side (Fig. 3a). She expressed great concern about what she perceived as unacceptable aesthetics. The teeth were prepared for fullcoverage restorations owing to the extensive fillings and need to change her occlusion and vertical dimension of occlusion radically (Fig. 3b). All of the maxillary teeth were restored with full-coverage crown restorations fabricated with e.max. This material was selected basedonitsstrengthanddurability, which would be necessary to establish a new and comfortable occlusion and desirable aesthetic outcome (Fig. 3c). Case 4 The patient presented with mesial decay on a maxillary molar (Figs. 4a & b). A minimally invasive mesial–occlusal inlay preparation was performed in anticipation of a lithium disilicate restoration. The preparation maintained the enamel on all of the peripheral margins. The mesial–occlusal inlay was placed and adhesively bonded to the enamel along all of the margins (Fig. 4c). Once placed, superior aesthetics and marginal fit were confirmed. The lithium disilicaterestorationdecreasedthe flexure of the tooth dramatically, which possibly decreased the risk of future facture. Case 5 A patient presented with significant mesial–occlusal decay of a maxillary first molar (Figs. 5a & b). The tooth preparation was performed for an onlay fabricated from e.max by hollow grinding the internal aspects of the tooth and finishing all of the margins on the enamel. The onlay was adhesively bond ed entirely to the enamel with Multilink N cement (Fig. 5c). This procedure was minimally invasive, and the ceramic material provided a successful longterm result. Case 6 The patient presented needing an implant abutment. A stock titanium abutment (Bio- Horizons) with Laser-Lok was used to wax and press an e.max implant abutment, which would be cemented on to the titanium abutment (Figs. 6a– c). Since allceramic restorations can be subject to failure from the inside out, the stiffness of the core material, or modulus of elasticity, was a consideration. A titanium abutment with a high elastic modulus minimizes failure when lithium disilicate or zirconia is used. The pressed e.max was cemented to the titanium abutment in the mouth using Multilink Implant cement (Ivoclar Vivadent; Figs. 6d–f) This represents an entirely different method of implant restoration that is easier and less expensive (Figs. 6g & h). Case 7 A patient presented with minimal enamel that was chipping off the maxillary anterior teeth (Fig. 8a). There was insufficient enamel to support a veneer restoration, so the teeth were prepared for full- coverage restorations. Because e.max reflects light in a manner similar to natural enamel and has the same wear coefficient, it was the ideal material in this case. The maxillary reconstruction using e.max restorations demonstrated enhanced aesthetics and predictable function (Fig. 8b). Case 8 The patient presented needing a complex reconstruction involving individual tooth and implant restorations, as well as periodontal therapy (Fig. 9a). The implants were placed, the teeth prepared, and a ceramic core cemented on to the man - dibular right second molar (Fig. 9b). The individual e.max restorations were fabricated and demonstrated superior aesthetics and occlusion compared with the patient’s previous treatment (Fig. 9c). Case 9 Apatientpresentedwithperiodontal disease and significant decay (Fig. 10a), resulting in the need to extract some of the teeth in the maxillary left quadrant and place implants. Additionally, there was a significant problem concerning the vertical dimension of occlusion and lack of anterior guidance. In addition, the patient was very unhappy with the aesthetics of the teeth. A metal–ceramic implant prosthesis was placed in the maxillary left quadrant, and all of the individual lithium disilicate crowns were fabricated to realise a more functional and aesthetic reconstruction. By using lithium disilicate principally as a monolithic material in this case, the laboratory time to fabricate these restorations was two-thirds less than when a metal core is made and a ceramic layered over it (Fig. 10b). Conclusion I have maintained a database for the last 30 years of different confounding variables and papers on the long-term survival rates of ceramic materials and the conditions that promote failure. Previously, the best longterm survival of a restoration that has been studied was the monolithic leucite-reinforced glass-ceramic (IPS Empress, Ivoclar Vivadent). It has been demonstrated that e.max can be used universally and effectively in all areas of the mouth, including the posterior region, making it suitable for a range of indications. It has been studied repeatedly to confirm its strength and functionality, and my research confirms that lithium disilicate has been used with impressive long-term success (Fig. 11). A list of references is available from the publisher. Fig. 8a: The patient presented with minimal enamel, and the teeth were prepared for full-coverage restorations. Fig. 8b: The maxillary reconstruction with lithium disilicate restorations demonstrated enhanced aesthetics and function. Fig. 9a: A patient presented requiring a complex reconstruction involving individual tooth restorations and implants, as well as periodontal therapy.— Fig. 9b: Implants were placed, preparations completed, and a ceramic core cemented on to the mandibular right second molar. Fig. 9c: The individual lithium disilicate restorations were fabricated and demonstrated improved aesthetics over previous restorations. Fig. 10a: The patient presented with periodontal disease and significant decay.—Fig. 10b: A metal–ceramic implant prosthesis was placed in the maxillary left quadrant, and all of the individual lithium disilicate crowns were fabricated to create a more functional and aesthetic reconstruction. Fig. 11: Chart documenting the author’s clinical success using lithium disilicate restorations. Dr Kenneth Malament maintains a full time private practice limited to prosthodontics in Boston, MA, USA. He can be contacted at ken.malament@verizon.net. Contact Info