Methods, Materials and Madness

Transcription

1 Methods, Materials and Madness 1960 s- occlusion/gnathology 1970 s- perio 1980 s- composite/adhesion 1990 s- tooth colored stuff fixing stuff digital technology - materials - fabrication techniques LAB DIAGNOSTIC SEQUENCE 1. Global Diagnosis and Tx as Needed 2. Healthy TMJ s with Models Mounted to CR 3. Upper Anterior Incisal Edges for Aesthetics 4. Lower/Upper Incisal Planes Parallel and Coupled 5. Evaluate Need for VDO Change 6. Level Lower Occlusal Plane Side to Side and Front to Back 7. Coordinate Upper Posterior to Lower Posterior Anterior Guidance: It s effect on electromyographic activity of the temporalis and masseter muscles. Williamson and Lundquist Anterior contact in centric has an inhibitory effect on temporalis and masseter contraction; Posterior contact overrides this inhibition. Mann, JPD, May 1989 Canine guidance always has less muscle activity than group function. Mann, JPD, April 1987 CLINICAL RESTORATIVE SEQUENCE 1. Global Diagnosis and Tx as Needed 2. Healthy TMJ s Treated to CR 3. Open VDO with Premolar Stops as Per Wax Up Open the estimated amount that was opened in Dx Wax Up. Use Stops in CR to serve as a stable stop and VDO reference 4. Upper Anterior Incisal Edges for Aesthetics 5. Level Lower/Upper Incisal Planes Parallel and Coupled Coupling is adjusted so teeth go back into premolar stops. Now coupled anterior serves as VDO reference Now aesthetics and Guidance has been satisfied Anterior Guidance dictates the shapes/contours of. 6. Level Lower Occlusal Plane Side to Side and Front to Back 7. Coordinate Upper Posterior to Lower Posterior

2 One of the most important factors in determining the longevity of the tooth/restoration complex is the amount of remaining tooth structure Dr. Terry Donavan With partial veneer restorations we shift the probable mode of failure from the to the Dr. John Kois Ceramics do not fail because their strength is insufficient, they fail because of placed on them, fatigue & defect propagation.... rather than inherent properties of the material, is the most important factor relating to the load required to initiate radial fractures. Rekow, D., Zhang, Y., Thompson, V. Compendium, July, 2007 Laminate Veneer Preparation Design Shadow Full Coverage Preparation Design

3 Finite Element Analysis of Preparation Finish Lines S tre s s (p s i) % re d u c tio n Shoulder Radial shoulder Deep chamfer Mullasseril PM, et al, JPD, in progress Rules for Bonded Porcelain Restorations Axial Reduction- mm Occlusal Reduction- mm Transition Reduction- mm Elevation Changes- Rounded Heavy Chamfer or Moderate Shoulder No Sharp Internal Line Angles SUPEROXYL Don t pass over the face Avoid skin No cotton rolls 10 Minutes- go! Effects on bond strength? Properties of Ideal Restorative Material? 1. Surface Hardness equivalent to or lower than 2. Material does not fatigues with time/use 3. Fracture proof in dimensions of less than mm 4. Optimizes aesthetic outcome 5. Familiar fabrication and delivery techniques Principles of Predictable Bonding & is more fracture resistant than & Enamel surface area makes more difference than the bonding materials or techniques Unfortunately many clinicians and more importantly those in the dental (materials) industry, have lost sight of the most significant determinate of success with resin-bonded restorations: the bond to enamel.

4 Regardless of the adhesive type or generation employed, ultimately clinical success with resin-bonded restorations is determined primarily by the quality of the bond to enamel, not to dentin. Dr. Harold Heymann, Prof. Univ. of North Carolina Inside Dentistry, August 2013 Resin Adhesive Classifications Total Etch- Primer/Adhesive 4th Generation- 3 component system acid primer adhesive Scotchbond Multi-Purpose- 3M ESPE All-Bond 3- Bisco Probond- Dentsply Caulk Optioned FL- Kerr Syntac- Ivoclar 5th Generation- 2 component system acid primer/adhesive Single Bond Plus- 3M ESPE All-Bond TE- Bisco Prime & Bond NT or XP- Dentsply Caulk Optioned Solo Plus- Kerr Excite F- Ivoclar Vivadent Light Cure Only Veneers Only Color Stable Simple Use Light/Duel Cure Option Suitable for all Restorations May Discolor Duel Cure Suitable for all Inlays, Onlays and Crowns Not Recommended for Veneers Self Etching Primer/Adhesive- 6 th Generation Shorter Window of Contamination Possibly minimizes post-op sensitivity Strong bond to dentin Bond strength to enamel is questionable NOT recommended for veneers

5 Self Adhesive 7th Generation Rely X Unicem- 3M ESPE BisCem- Bisco Smartcem 2- Dentsply Caulk Maxcem Elite- Kerr Speedcem- Ivoclar Vivadent G-Cem- GC America Panama SA- Kurary America Shortest Window of Contamination Minimum Post-Op Sensitivity Weak bond to Enamel Not Recommended for Veneers All Ceramic Restorations High Strength Cores- Requires more tooth reduction! Must have adequate retention/resistence Zirconia Core ( MPa)- Lava, E Max Zircad, Procera Zircon, Everest, Inceram Alumina Core ( MPa) Procera, Inceram Layering High Strength Cores- Chipping Bonded Ceramics Lithium Disilicate ( MPa) Leucite Reinforced ( Mpa) Feldspathic Veneers ( MPa) in the back for strength, in the front for aesthetics Bond strength is reduced with time when in a wet environment ZIRCONIA Wear Behavior of BruxZir (In process) Research sponsored by Glidewell Laboratories Samples tested by Prof. De. Jurgen Geis-Gerstorfer University Hospital, Tubingen, Germany Low Temperature Degradation (LTD) is defined as the spontaneous tetragonal to monoclinic transformation occurring over time at low temperatures......transformation also occurs in the presence of hydrothermal stress such as water, blood, and synovial fluids over a long period of time and is considered unfavorable

6 because the excess volume is not compensated by crack space and causes micro and macro-cracking, reducing the mechanical properties. Facts about Zirconia 1. Zirconia does not wear. 2. Physical strength and ability to resist fatigue fracture is dependent upon. There are over 50 different manufacturers and labs have no idea of manufacturing standards for a given material. 3. Is inherently opaque in color thus mask underlying discoloration well. 4. Due to the ability to mask color, restorations can tend to be bright or in value. 5. More translucent zirconia materials are now available. These materials have and reduced resistance to fracture. 6. Serious chipping and failure of laying porcelain has been reported. 7. Zirconia is susceptible to. The milling process damages the material which persists even after it has been heat cycled. 8. If there is grinding on a restoration after it is manufactured, phase transfer to a weakened state occurs. See #7 and #9. 9. Hydrothermal temperature changes contribute to a state. As this weakened state develops is transformed into a more abrasive material. 10. When not highly polished, zirconia is it a highly abrasive material. Glazing is highly polished. 11. Because the internal surface is smooth, and because Zirconia cannot be bonded in place, using it as a partial coverage restoration is not indicated. 12. Post cementation removal is very difficult. 836 subjects yo Tooth wear initially in anterior teeth As teeth wore they all turned into group function 3% of population have bilateral contact with canines (non ortho or restorations) 10% have unilateral canine contacts Wear is a general phenomena that happens in everyone and happens more as we age. Our restorations should wear similar as teeth for adaptation to the changing system. Woda Study-JPD yo with no restorations, no ortho, class 1 with minimal wear. All teeth except lateral incisors had wear facets. Working side wear facets evident on all post teeth. Non-Working wear facets on all 1-2 molars and most premolars. If dental wear is a natural process, then the introduction of a restoration that are more abrasive than enamel, we will alter the systems ability to adapt. In other words something else will suffer!

7 Facts about Lithium Disilicate