implants - international magazine of oral implantology

gous to the use of a long, tapered friction-fit interface with a retaining screw (Morse taper) to secure an abutment to a fixture. In both cases, the role of contact pressure between mating surfaces in generating frictional resistance provides a locked connection. This has been shown to effect long-term stability of crestal bone support for the overlying gingival tissues and maintain a healthy protective and aesthetic periodontal attachment apparatus.47 The Roman architect Vitruvius’ (Marcus Vitruvius Pollio) description of the per- fect human form in geometrical terms was a source of inspiration for Leonardo da Vinci, who successfully illustrated the proportions outlined in Vitruvius’ work De Architectura.Theresult,theVitruvianman,isoneofthemostrecogniseddrawings in the world and is accepted as the standard of human physical beauty. Vitruvius theorised that the essential symmetry of the human body with arms and legs ex- tended should fit into the perfect geometric forms: the circle and the square. Da Vinci recognised that the circle and the square are only tangent at one place, the base. Observe the insert in Figure 8. The stabilising platform for the human form outlined begins at that tangent; the intersection is graphically analogous to the structural configuration of platform switching. The relative simplicity of this construct reinforces the obvious. When we com- pare design in living things to the artificial designs they inspire, a striking parallel emerges. Almost all the products of man’s technology are no more than imitations of those in nature and usually, they fail to match the superior design in living things. Consider the engineering perfection that is the egg. Its strength lies in its oblatespheroidshape.Ablowtothesideofaneggfromasharpobjectplacespres- sure along the thin shell and breaks it easily. However; if the egg is squeezed di- rectly on its poles, the vectored pressure is compressed along the surface struc- ture, not across the shell; the egg cannot be broken without extraordinary force. However, if a pinhole is created in one of the poles disrupting the integrity of the structure,thepressurewillreadilybreaktheegg,commensuratewithasharpblow to the side. In geometry, an oval is a curve that resembles an egg or an ellipse. Architects and engineers have used smooth ovate curves to support the weight of structures over an open space literally since the second millennium BC. These arches, vaults and domes can be seen in buildings and bridges all over the world; the most per- vasive example is the keystone arch used by the Romans for aqueducts and mills. An arch directs pressure along its form so that it compresses the building ma- terial from which it is constructed. Even a concrete block is readily broken if one hitsitonthesidewithasledge.Butundercompressionforcesfromabove,theblock is incredibly strong and unyielding. Many will remember the weight-bearing tri- pod experiments from grade school in which an egg acts as one of three support- ing legs of a square section of wood that bears books as the load. The structure could support over sixty books, almost twenty pounds (9 kilograms), before break- ing the supporting egg. One need only look at the root trunk and coronal tooth structure of a multi-rooted teeth and it becomes apparent that strength of the tooth form is dependent upon an arch form for its integrity (Figs. 8 & 9). Is it possible for this natural feat of engineering to be biomimetically replicated to the design parameters of osseointegrated implants? There are a number of par- adigms that continue to fuel debate in the dental clinical and scientific communi- ties that pertain to the optimal engineering predicates for implant design. These include smooth versus rough surfaces, submerged versus non-submerged instal- lation techniques, mixed tooth-implant versus solely implant-supported recon- structions, Morse taper abutment fixation versus a butt-joint interface, and tita- nium abutments versus aesthetic abutments in clinical situations in which aes- thetics are of primary concern. Augmentation versus Prävention Wissenschaftliche Leitung: Prof. Dr. W. Lückerath Kongress-Anmeldung: www.dsdental.ch/Kongress Telefon: 0180 13 73 368 24.–25. Juni 2011, Luzern 5th Swiss Bio- material Days Speakers: Prof. Dr. Wilfried Engelke, Göttingen Prof. Dr. Walter Lückerath, Bonn Prof. Dr. Else Marie Pinholt, Kopenhagen Prof. Dr. Dr. Rudolf Reich, Bonn Dr. Georg Bach, Freiburg im Breisgau Dr. Peter Fairbairn BDS, London Dr. Dr. Karl-Heinz Heuckmann, Chieming Dr. Stefan Neumeyer, Eschlkam Dr. Detlef Klotz, Duisburg Dr. Kurt Ruffieux, Zürich Dr. Jens Schug, Zürich PD. Dr. Patrick Schmidlin, Zürich Dr. Dr. Angelo Trödhan, Wien Dr. Mario Kirste, Frankfurt Dr. Gerhard Werling, Bellheim Prevention versus augmentation Scientific chair: Prof. Dr. W. Lückerath Registration: www.dsdental.ch June 24–25, 2011, Lucerne AD