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implants - international magazine of oral implantology

Available implant lines: 1.TRI® -Friction Secure frictional implant-abutment connection Elimination of micro movements Seal effect for platform switching 2.TRI® -BoneAdapt Step-design for ideal bone adaptation Progressive cutting design Protected cortical design 3.TRI® -Grip Increased primary stability Enhanced control during placement Superior guidance and direction TRI® Performance Concept Through Research Innovative www.tri-implants.com Free Infoline: 00800 3313 3313 The Swiss implant provider TRI Dental Implants presents its patented TRI® implant concept with three essential success factors - released after test market with 5000 implants. *Offer only includes titanium abutments **Registered trademarks of Zimmer Dental and Camlog AG. Test our free introductory implant set. Each additional implant incl abutment 150 Euro*. AD Wheneverpossible,thetreatmentchoiceshouldbeanattempttosalvageatooth using a multidisciplinary team approach, putting aside preconceived notions and biases.Financesshouldnotdictatetheadviceproffered.Furthermore,itisadvisable toforegobeingclinically‘conservative’.Treatmentshouldnotbeinitiatedintheab- sence of a critical evaluation of the potential for all contributing factors to equate to a positive outcome. When needed, care must be taken to carry out every diag- nostic procedure available, even those of a more invasive nature (Fig. 1). Before ar- riving at a definitive diagnosis and treatment plan, the clinician should obtain con- sent from the patient to remove any restoration in order to analyse the residual tooth structure and assess the potential to carry out reliably predictable treatment. The patient must understand in detail, the feasibility of and margin for success of each treatment option presented.14 There are few studies in the endodontic literature analysing the reasons for ex- traction of endodontically treated teeth. Root-filled teeth are invariably prone to extraction due to non-restorable carious destruction and fracture of unprotected cusps. Tamse etal. found that mandibular first molars were extracted with greater frequency than maxillary first molars; the most significant causal difference was the incidence of vertical root fracture (VRF—1.8% maxillary molar, 9.8% mandibu- larmolar).15 Teethnotcrownedafterobturationarelostwithsixtimesthefrequency of those restored with full coverage restorations.16 Procedural failure, iatrogenic perforation or stripping, idiopathic resorption, trauma and periodontal disease all contribute to a lesser degree. The major biological factor that influences endodontic treatment outcome failure with the possibilityofextractionappearstobetheextentofmicrobiologicalinsulttothepulp and peri-apical tissue, as reflected by the peri-apical diagnosis and the magnitude of peri-apical pathosis (Table I and Figs. 2a–c).17 Dentine is the most abundant mineralised tissue in the human tooth. In spite of thisimportance,overhalfacenturyofresearchhasfailedtoprovideconsistentval- ues of dentine’s mechanical properties. In clinical dentistry, knowledge of these propertiesispivotaltoanynumberofvariables,rangingfrominnovationsinprepa- ration design to the choice of bonding materials and methods. The Young’s modu- lus(themeasureofthestiffnessofanisotropicelasticmaterial)andtheshearmod- ulus (modulus of rigidity) are diminished by viscoelastic behaviour (time-depend- ent stress relaxation) at strain rates of physiological (functional) relevance. The re- portedtensilestrengthdatasuggeststhatfailureinitiatesatflaws.Theseflawsmay be intrinsic, perhaps regions of altered mineralisation, or extrinsic, caused by cav- ity or post-channel preparation, wear, or damage. There have been few studies of fracture toughness or fatigue.18 Finally, little is known about the biomechanical properties of altered forms of dentine subsequent to decay, the influence of irrig- ants and chemicals, and the choice of curing techniques used for bonded restora- tions.19 Studiessuggestthatthereareatleasttwoformsoftransparentorscleroticden- tine: a form associated with caries and a form associated with age-related changes in the root. The impact upon tooth strength as a function of these altered forms of dentine is not well understood. The long-term predictability of residual coronal tooth structure to function in a manner commensurate with the demands of the orofacial ecosystem may need to be reassessed in light of observations that scle- roticdentine,unlikenormaldentine,doesnotexhibityieldingbeforefailureandthat the fatigue lifetime is deleteriously affected at high stress levels.20 Mechanisms for energy dissipation and crack growth resistance present in young dentine are not present in old dentine. Restorative methods and techniques, particularly regarding ferrule creation for endodontically treated teeth, may need to be amplified to ad- dress the fact that fatigue crack growth resistance of dentine decreases with age (Fig. 3).21