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1400 Average Flexural Strength Distribution 1300 Flexural strength (MPa ) 1200 1100 1000 900 800 sagemax ht zirconia DoCERaM zirconia amann Girrbach zirconia Zirkonzahn zirconia Cercon zirconia BruxZir ® zirconia Figure 2: Graph showing the average flexural strength distribution of monolithic zirconia products, as tested by <strong>Glidewell</strong> Laboratories FRACTURE TOUGHNESS Fracture toughness (K 1c value) is a quantitative way of expressing a material’s resistance to brittle fracture when a crack is present. Materials such as lead or steel, for example, demonstrate high fracture toughness, whereas most ceramic and glass-ceramic materials exhibit low and inconsistent fracture toughness. This means that a crack can travel through a typical ceramic with little resistance, resulting in immediate, brittle fracture and catastrophic failure. Partially stabilized zirconia, however, contains an internal mechanism that actually inhibits crack propagation. This “self-healing” event is known as phase transformation toughening. When faced with a propagating crack tip, a zirconia grain particle is able to absorb the associated energy by transforming from its tetragonal phase to the more stable monoclinic phase. This results in an associated volumetric expansion, effectively closing the advancing crack. Transformation toughening gives partially stabilized zirconia a K 1c value that is three to six times higher than normal cubic zirconia and most other ceramics, resulting in tremendous impact resistance. Figure 3: Spring fabricated from BruxZir zirconia Figure 4: Compressed BruxZir zirconia spring 32 – www.inclusivemagazine.com –
CONCLUSION Partially stabilized zirconia … contains an internal mechanism that actually inhibits crack propagation. The fastest-growing product in the 42-year history of <strong>Glidewell</strong> Laboratories, BruxZir Solid Zirconia has quickly proven itself as a reliable, esthetic alternative to traditional PFM and full-cast restorations. Manufactured from yttriastabilized zirconia powder specially processed to achieve a nanocrystalline particle size as small as 3 nm, BruxZir zirconia exhibits class-leading strength and flexibility in addition to its high biocompatibility. These mechanical properties enable it to absorb high levels of functional stress, making it an ideal material choice for implant-borne restorations, whether cement-retained or screw-retained (Figs. 5, 6). IM As a demonstration of this principle, note the fabrication of BruxZir zirconia into a spring-shaped coil (Fig. 3). Due in part to its high K 1c value and ability to transform its structure, this coil can endure repeated compression cycles (Fig. 4), returning each time to its original shape without suffering the fracture damage one might expect of a typically brittle ceramic. COEFFICIENT OF FRICTION Although dependent on system variables such as temperature, velocity and atmosphere, the coefficient of friction (COF) is often stated as a material property that describes the ratio of the force of friction between two bodies and the force pressing them together. Ice on steel, for example, would tend to have a low COF, while rubber on pavement tends to have a high COF. A material with a low COF value, such as that exhibited by BruxZir zirconia, can be perceived then as having a greater resistance to frictional wear present in any nanomechanical system, enabling it to better withstand the rigors of micromovement. Figure 5: Cement-retained BruxZir crown with Inclusive ® All-Zirconia Custom Implant Abutment COEFFICIENT OF THERMAL EXPANSION The coefficient of thermal expansion (CTE) describes how the size of an object changes with a change in temperature. In general, substances expand or contract when their temperature changes, with expansion or contraction occurring in all directions. This causes strain within the material, which again can introduce the potential for fracture. A lower CTE number indicates greater resistance to thermal shock. Because the oral environment is highly susceptible to rapid temperature changes, a material like BruxZir zirconia, characterized by a relatively low CTE, is better suited to withstand the rigors of that environment than a material with a higher CTE. Figure 6: Screw-retained BruxZir crown R&D Corner: Strength and Flexibility of BruxZir Solid Zirconia Implant Restorations 33
Page 1 and 2: Inclusive Restorative Driven Implan
Page 3 and 4: Contents 13 Intraoral Scanning and
Page 6 and 7: Publisher Jim Glidewell, CDT Editor
Page 8 and 9: Contributors ■ Bradley C. Bockhor
Page 10 and 11: Trends in Implant Dentistry Custom
Page 13: my first implant with Gordon J. Chr
Page 16 and 17: Figure 4: Following a six-month oss
Page 18 and 19: 18a 18b 18c Figures 18a-18c: The co
Page 21 and 22: Guided Implant Surgery for Single-T
Page 23 and 24: Figure 2: Tongue depressors used to
Page 25: 10a Summary Digital treatment plann
Page 29 and 30: Type D1 Type D2 Endodontic probe be
Page 31: 1Prosthetic guide in situ Because t
Page 37 and 38: The Do’s and Don’ts of Immediat
Page 39: cases, the caveats noted previously
Page 42 and 43: Step-by-Step 1Seat the temporary ab
Page 44 and 45: Implant& Q A: Go online for in-dept
Page 46 and 47: We have been working with dedicated
Page 48 and 49: had another way to put the occlusal
Page 50 and 51: PRODUCTION WORKFLOW The following o
Page 52 and 53: The Critical Nature of Tissue Conto
Page 54 and 55: attempts to shape the tissues with
Page 56: As implant dentistry is a restorati
Page 59 and 60: Adjusting the Inclusive Custom Temp
Page 61 and 62: Delivering the Provisional Restorat

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