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Implant prototypes and_designs
- 1. IMPLANT PROTOTYPES DESIGNS ANDSYSTEMS (How to select an implant system) Objectives Participants will understand the rationale behind the design of the root form implant. They will be given an over view of the other types of Implant systems. Nobel Replace® and Nobel Active ® designs will be discussed in some detail. At the end of the course they will be in a position to select an implant and a system on a scientific basis. DEFINITION : A Dental Implant is defined as “ A substance that is placed into the jaw to support a crown or fixed or removable denture.” History ANCIENT IMPLANTS :- Ú 16 th Dark stone ( Egyptian-South American) Ú 17 th Carved ivory teeth EARLY IMPLANTS :- Ú 1809 Gold implant Ú e.20th Lead, iridium, tantalum, stainless steel, & cobalt alloy Ú 1913 hollow basket, iridium + gold wires EARLY IMPLANTS Ú 1937 Adams’s submergible threaded cylindrical implant with round bottom Ú 1938 Strock’s (long term) threaded vitallium implant (cobalt+chrome+molybdenum) Ú The modern implants appear to be variants or composites of some of the designs of early implants
- 2. DENTAL IMPLANT DESIGNS EndostealImplants Root/Blade Subperiosteal Implants Transosteal Implants Intramucosal implants Dental Implant Designs Endosteal Implants Root /Blade Subperiosteal Implants Transosteal Implants Intramucosal implants AN ENDOSTEAL IMPLANT IS PLACED DIRECTLY INTO THE BONE, LIKE NATURAL TOOTH ROOTS AND CAN BE USED FOR MANY PURPOSES. A SINGLE PIN CAN BE INSERTED THROUGH AN EXISTING TOOTH TO STRENGTHEN AND STABILIZE IT. OTHER STYLES CAN PROVIDE AN ANCHOR FOR ONE OR MORE ARTIFICIAL TEETH. Root Form Dental Implants Solid Tapering types Solid cylinder Pin types Screw shaped implant type Hollow cylinder design Basket design Solid Tapering types Solid cylinder Pin types Screw shaped implant type Basket design/BOI
- 3. Hollow cylinder design DentalImplant Designs Endosteal Implants Root/ Blade Subperiosteal Implants Transosteal Implants Intramucosal implants
- 4. BLADE IMPLANT IT ISA BLADE PLACED DIRECTLY INTO BONE AND MAY BE SOLID OR VENTED. IT MAY BE USED TO SUPPORT SINGLE OR MULTIPLE TEETH. IT USES THE CONCE SUBPERIOSTEAL IMPLANT: IS USED WHEN THE BONE HAS ATROPHIED AND JAW STRUCTURE IS LIMITED. THE LIGHTWEIGHT, INDIVIDUALLY BONE, PROVIDING THE EQUIVALENT OF MULTIPLE TOOTH ROOTS. IT MAY BE USED I AREA OR, IF ALL THE TEETH ARE MISSING IN THE ENTIRE MOUTH Subperiosteal Implants IT IS A BLADE PLACED DIRECTLY INTO BONE AND MAY BE SOLID OR VENTED. IT MAY BE USED TO MULTIPLE TEETH. IT USES THE CONCEPT OF ‘FIBROOSSEOUS’ INTEGRATION SUBPERIOSTEAL IMPLANT: IS USED WHEN THE BONE HAS ATROPHIED AND JAW STRUCTURE IS LIMITED. THE LIGHTWEIGHT, INDIVIDUALLY-DESIGNED, METAL FRAMEWORK FITS OVER THE REMAINING BONE, PROVIDING THE EQUIVALENT OF MULTIPLE TOOTH ROOTS. IT MAY BE USED I AREA OR, IF ALL THE TEETH ARE MISSING IN THE ENTIRE MOUTH. IT IS A BLADE PLACED DIRECTLY INTO BONE AND MAY BE SOLID OR VENTED. IT MAY BE USED TO PT OF ‘FIBROOSSEOUS’ INTEGRATION IS USED WHEN THE BONE HAS ATROPHIED AND JAW STRUCTURE IS LIMITED. THE DESIGNED, METAL FRAMEWORK FITS OVER THE REMAINING BONE, PROVIDING THE EQUIVALENT OF MULTIPLE TOOTH ROOTS. IT MAY BE USED IN A LIMITED
- 5. A Letter tothe editor BDJ Sir, A 74-year-old patient was referred to the oral surgery department by her general dental practitioner. On consultation, the patient complained of a loose lower complete denture. She reported that she had undergone implant placement some 20 years previously in South Africa and that she had not attended for dental examination since. Clinical and radiographic examination revealed a subperiosteal mandibular implant (Figs 1,2). The bar was firm and the patient reported that she was experiencing no pain. There were multiple mucosal dehiscences anteriorly and posteriorly, with the exposure of necrotic bone. There appeared to be some deposits of calculus associated with the abutments. . Note dehiscences with bone exposure posteriorly, exposure of a screw in the lower left anterior region and calculus deposits around the posts Note radiolucencies adjacent to the anterior screws. The generalised lack of close fit to bony surface is likely related to continued ridge resorption Radiographic examination showed a metal framework spanning the entire edentulous mandible. It sat approximately 2-2.5 mm above the alveolar ridge. Due to the smooth bony border and the even loss across the mandible, this is most likely to be due to continued resorption over time rather than pathological bone loss due to infection. The framework was secured to the bone by four retaining screws: two anteriorly and two posteriorly. The mandible itself was atrophic, with radiolucencies evident around the two anterior retaining screws.
- 6. Complete subperiosteal implantplacement was first described as a treatment for the atrophic mandible in the 1940s. A mucoperiosteal flap would be raised to allow an impression to be made of the surface of the mandible. CT scans were also used to allow CAD/CAM fabrication of the framework, negating the need for impressions. The framework usually rests on the mandible, with no penetration into the bone. Due to the high success rates in atrophic mandibles of osseointegrated implants facilitated by the placement of autogenous grafts, subperiosteal implants are no longer used. However, as this case highlights, there may still be some in situwhich could present to the general dental practitioner. Manchester TRANSOSSTEAL IMPLANTS Transosteal or transosseous dental implants are implants composed of a metal plate and transosteal pins or posts. The metal plate is held with retentive pins or screws fixed to the inferior border of the mandible. This metal plate supports the transosteal pins/posts that penetrate the full thickness of the mandible and project into the mouth in the inter-foraminal area. The transosseous dental implants used in humans are the ‘staple bone implant’ system and the ‘transmandibular implant’ system (TMI). Transosteal Implants
- 7. INTRAMUCOSAL INSERTS REPRESENT AFOURTH TYPE OF IMPLANT USED WITH REMOVABLE DENTURES. THE MUSHROOM-SHAPED INSERTS ATTACH TO THE GUM-SIDE OF THE DENTURE AND FIT INTO SPECIALLY PREPARED INDENTIONS IN THE ROOF OF THE MOUTH. THEY PROVIDE GREATLY INCREASED STABILITY AND HOLDING POWER. Intramucosal implants
- 8. Implant BioMaterials A. Metalsand Alloys B. Inert ceramics C. Ca phosphate ceramics D. Bioactive and biodegradable ceramics E. Polymers Metals and alloys Titanium (Pure) 100% Cp Titanium Titanium alloy Titanium 90% Chromium 2% Molybedenium 7% Zirconium Chromium cobalt Cobalt 66% alloy Chromium 37% Molybedenium 7% Stainless Steel Iron 70% Chromium 18% Nickel12% Tantalum / Gold/ Platinium Inert Ceramics Aluminium oxide Al2O3 i. Polycrystalline ii. Single crystal Zirconium oxide ZrO2 Zircona
- 9. Titanium Oxide TiO2 ENGINEERINGPROPERTIES OF METALS AND ALLOYS USED FOR SURGICAL IMPLANTS Material Nominal Modulus of Ultimate Elongation Surface Analysis(w/o) Elasticity Tensile to Fracture(%) GN/m(psi x 10) MN/m(ksi) Titanium 99+Ti 97(14) 240-550(25-70) >15 Ti oxide Ti Al 90Ti-6Al-4V 117(17) 869-896(125-130) >12 Ti oxide vanadium Co CrMo- 66Co-27Cr-7Mo 235(34) 655(95) >8 Cr oxide (casting) Stainless steel 70Fe-18Cr-12Ni 193(28) 480-1000 >30 Cr oxide (316L) (70-145) Zirconium 99+Zr 97(14) 552(80) 20 Zr oxide Tantalum 99+Ta - 690(100) 11 Ta oxide Gold 99+Au 97(14) 207-310(30-45) >30 Au Platinum 99+Pt 166(24) 131(19) 40 Pt IMPLANT DESIGN
- 10. Crestal Module design Internalvs External Hex
- 11. Smooth vs Rough/Threaded Cylindervs Flare Platform switch vs Platform shift Smooth vs Rough/Threaded Platform switch vs Platform shift
- 12. Crestal Module design INTERNALvs EXTERNAL HEX vs TRI LOBE Precision fit Crestal Module design Smooth vs. Rough/Threaded INTERNAL vs EXTERNAL HEX vs TRI LOBE Smooth vs. Rough/Threaded
- 13. Crestal Module design Cylindervs. Flare Crestal Module design Platform switch vs shift When platform switching, a narrower abutment diameter for a given implant platform diameter is used; for example, placing a 3.8 However when the implant system provides for a NEP abutment then a Astra, Ankylos, or Bicon. 1) Esthetics. . 2) Implant Placement Flexibility Platform switch/shift , a narrower abutment diameter for a given implant platform diameter is used; for example, placing a 3.8 mm-wide abutment on a 4.8 mm-wide implant. Osstem plant system provides for a NEP abutment then a platform shift 2) Implant Placement Flexibility. , a narrower abutment diameter for a given implant platform diameter wide implant. Osstem platform shift is done.
- 14. Implant Body Design Cylindervs tapered threaded Thread shapes-V thread/buttress/r Thread geometry shape/pitch/depth Surface preparation-Ti plasma spray coating, sand blasting surface etching, acid etching, laser induced etching, HA coating , Ti Unite™, SLA® surface Flat /grooved areas Implant Body Design Implant Body design Thread Geometry Pitch/Shapes/Depth IMPLANT SURFACE Ti Plasma Spray Coating Implant Body Design Cylinder vs tapered threaded V thread/buttress/reverse buttress/square thread. Thread geometry shape/pitch/depth Ti plasma spray coating, sand blasting surface etching, acid etching, laser induced etching, HA coating , Ti Unite™, SLA® surface Thread Geometry Pitch/Shapes/Depth Ti plasma spray coating, sand blasting surface etching, acid etching, laser
- 15. Sand blasting surfaceetching Implant Body Surface Modification ACID ETCHING The acid etched dental implants were immersed in a mixture of HNO surface treatment, the samples were rinsed with distilled water, dried in an air furnace at 70 ºC for 2 h, packed and sterilized with gamma radiation (25 kgray). IMPLANT SURFACE MODIFICATIONS Laser induced etching/sintering SEM image of ablated holes formed on a titanium surface with 0.5 ps pulses of a KrF excimer laser. The laser fluence was 2.4 J/cm2 and 1000 shots were applied (Bereznai et al., 2003). Implant Body Surface H A COATING Sand blasting surface etching Implant Body Surface Modification The acid etched dental implants were immersed in a mixture of HNO3, HCl and H surface treatment, the samples were rinsed with distilled water, dried in an air furnace at 70 ºC for 2 h, packed and sterilized with gamma radiation (25 kgray). LANT SURFACE MODIFICATIONS Laser induced etching/sintering SEM image of ablated holes formed on a titanium surface with 0.5 ps pulses of a KrF excimer laser. The laser fluence was 2.4 J/cm2 and 1000 shots were applied (Bereznai et al., 2003). , HCl and H2SO4 After surface treatment, the samples were rinsed with distilled water, dried in an air furnace at 70 ºC SEM image of ablated holes formed on a titanium surface with 0.5 ps pulses of a KrF excimer laser. The laser fluence was 2.4 J/cm2 and 1000 shots were applied (Bereznai et al., 2003).
- 16. HA coatings ondental implants have been shown to accelerate surface bone apposition, shortening the waiting period for dental implant restoration. HA surface known to degrade and in some instances separates Implant Body Surface Ti Unite™ TiUnite is titanium oxide rendered into an osseoconductive ceramic biomaterial through spark anodization. Unlike implants with machined surfaces, TiUnite has clinically demonstrated the ability to increase the predictability and speed at which dental implants osseointegrate through osseoconductivity. Implant Body Surface SLA® surface Surface roughening is achieved through large grit sand-blasting with corundum particles followed by acid etching, commonly referred to as SLA® surface. The SLActive® surface has less surface tension and increases hydrophilic properties (wetability) intended to attract blood cells. SLActive® treated implants are stored and shipped in a vial filled with an isotonic liquid (salt water) to preserve the reduced surface tension qualities of the implant. Implant Body Design Cylinder vs tapered threaded
- 17. Apex design Tapered Antirotational Feature Hole/Vent Grooves/Flatsides Flat /Rounded End NobelReplace™ Tapered History of NobelReplace™ Evolution of NobelReplace™ Easy to use
- 18. Prosthetic connection designfor ease of use and to stabilise prosthetic Standardized tapered drilling protocol Groovy to enable faster bone formation Coronal design to improve soft tissue support Tapered body design for optimal initial stability Triunite oxidised surface to enhance osseointegration NobelReplace™ – Strong user benefits Tri-channel internal connection Color-coding The implant of choice for Advanced Users Prosthetic connection design for ease of use and to stabilise prosthetic restorations Standardized tapered drilling protocol Groovy to enable faster bone formation Coronal design to improve soft tissue support Tapered body design for optimal initial stability Triunite oxidised surface to enhance osseointegration Strong user benefits channel internal connection The implant of choice for Advanced Users: Treatment predictability/Safety restorations
- 19. Ease-of-use, simplified drillingprotocols, consistent restorative ou stability allows the use of NobelReplace also in more demanding indications. Clinical flexibility Satisfies broad range of indication: from single tooth to fully edentulous restorations as well as temporary solutions. Due to its placement in extraction sites. Suitable for NobelGuide Prosthetic versatility Tri-channel connection supports all types of restorative solutions including individualized NobelProcera prosthetic sol long term esthetics and functionality. NobelReplace™ Tapered Groovy TiUnite “all the way up” • Strong and faster osseointegration than machined surface implants Grooves on Threads • Bone is formed more rapidly inside the groove High stability Grooves on Collar • Intended for hard and soft tissue stabilization and improved long term esthetics use, simplified drilling protocols, consistent restorative outcomes and optimal initial stability allows the use of NobelReplace also in more demanding indications. Satisfies broad range of indication: from single tooth to fully edentulous restorations as well as temporary solutions. Due to its tapered design NobelReplace is also ideal for immediate placement in extraction sites. channel connection supports all types of restorative solutions including individualized NobelProcera prosthetic solutions. It also secures accurate prosthetic positioning and provides long term esthetics and functionality. NobelReplace™ Tapered Groovy osseointegration than machined surface implants Bone is formed more rapidly inside the groove for hard and soft tissue stabilization and improved long term esthetics tcomes and optimal initial Satisfies broad range of indication: from single tooth to fully edentulous restorations as well as tapered design NobelReplace is also ideal for immediate channel connection supports all types of restorative solutions including individualized utions. It also secures accurate prosthetic positioning and provides for hard and soft tissue stabilization and improved long term esthetics
- 20. Differences between Replace™ SelectTapered and NobelReplace™ Tapered Implant surface and grooves Bone forms faster within the grooves, compared to implant surfaces without grooves Resulting in higher implant stability2 Grooves on collar:designed esthetics 1.Zechner et al. Clin Oral Implants Res 2003 SINGLE TOOTH RESTORATION Young female, non-smoker, no parafunctional habit, persistent deciduous lateral incisor Diagnosis Extraction of persistent deciduous lateral incisor. Orthodontic treatment finalized. Missing lateral central incisor, limited space to adjacent teeth. Treatment Insertion of a NobelReplace Tapered Groovy NP/13 mm implant, intraoperative X-rays shows narrow space conditions, immediate loading with a temporary resin crown. Replace™ Select Tapered and NobelReplace™ Tapered surface and grooves – Osseointegration1 Bone forms faster within the grooves, compared to implant surfaces without grooves Resulting in higher implant stability2 for hard and soft tissue stabilization and improved long term Zechner et al. Clin Oral Implants Res 2003 SINGLE TOOTH RESTORATION smoker, no parafunctional habit, persistent deciduous lateral incisor Extraction of persistent deciduous lateral incisor. Orthodontic treatment finalized. Missing lateral central incisor, limited space to adjacent teeth. Insertion of a NobelReplace Tapered Groovy NP/13 mm implant, shows narrow space conditions, immediate loading with a temporary resin crown. Bone forms faster within the grooves, compared to implant surfaces without grooves for hard and soft tissue stabilization and improved long term smoker, no parafunctional habit, persistent deciduous lateral incisor Extraction of persistent deciduous lateral incisor. Orthodontic treatment finalized. Missing lateral central shows narrow space conditions, immediate loading with a temporary resin crown.
- 21. Treatment Insertion of aNobelReplace Tapered Groovy NP/13 mm implant, intraoperative X-rays shows narrow space conditions, immediate loading with a temporary resin crown. Results Excellent esthetics and soft tissue response shortly after final esthetic installed and after three years Multiple teeth restoration Young female, came to clinic because of trauma against central incisors Treatment Atraumatic extraction of central incisors. Flapless immediate implant placement 2 NobelReplace Tapered Groovy, WP Platform Shifting. Products used 2 NobelReplace Tapered WP 2 NobelProcera Zirconia Abutments 2 NobelProcera Alumina Crowns Results 2 NobelProcera Alumina Crowns (Graft for soft tissue thickness). NobelActive™ design Insertion of a NobelReplace Tapered Groovy NP/13 mm implant, rays shows narrow space conditions, immediate loading with a temporary resin crown. Excellent esthetics and soft tissue response shortly after final esthetic installed and after three years Young female, came to clinic because of trauma against central incisors extraction of central incisors. Flapless immediate implant placement 2 NobelReplace Tapered Groovy, WP Platform Shifting. 2 NobelReplace Tapered WP 2 NobelProcera Zirconia Abutments 2 NobelProcera Alumina Crowns a Crowns (Graft for soft tissue thickness). rays shows narrow space conditions, immediate loading with a temporary resin crown. Excellent esthetics and soft tissue response shortly after final esthetic installed and after three years extraction of central incisors. Flapless immediate implant placement 2 NobelReplace
- 22. • Expanding taperedbody with double variable thread design and apical drilling blades. • Manual insertion protocol Benefits • Gradual bone condensing and high initial • Enables ”active” directional changes for optimal restorative position NobelActive™ design Features: Triunite groovy Features Expanding tapered body with double variable thread design and apical drilling blades. Gradual bone condensing and high initial stability Enables ”active” directional changes for optimal restorative position Expanding tapered body with double variable thread design and apical drilling blades.
- 23. Benefits • Documented toenhance osseointegration and increase of the predictability of implant treatment1 • Bone forms faster within the grooves, compared to implant without grooves2 NobelActive™ design Benefits • Allows for maximum alveolar bone volume around implant for improved soft tissue support Animation: Bone condensing NobelActive™ design Features: APICAL:Drilling blades on apex. BENEFITS:
- 24. Enable smaller osteotomy. NobelActive™design Features • Conical connection • Built-in Platform Shifting Benefits • Sealed connection • Increased mechanical strength • Designed to enhance Soft Tissue Integration • NOBEL ACTIVE DESIGN • FEATURES:Hexagonal interlocking • Benefits
- 25. • Secure repositionof prosthetic components • Allows for prosthetic flexibility and implant level bridges Dual-function prosthetic connection NobelActive™ Macro Design Features 1. Coronal portion back taper (except 3,5) • Maximizes the volume of alveolar bone around the implant 2. Constantly expanding central core • Acts like a threaded osteotome • Compacts the bone outward • Provides excellent primary stability 3. Sharp blades, deep widely spaced 35º double lead threads • Allows implant to condense through bone • Actively changes direction Titanium Abutment Fit Into Implant
- 26. Insertion Torque Discussion Insertiontorque requirements for different implant designs are not comparable. The NobelActive implant requires higher insertion torque due to the large helix angle of the thread For each rotation, the implant advances 2.4 mm Occlusal Forces and Implant Design Stress and strain cause crestal bone loss and decrease long term survival of implant. Force applied to dental implants may be characterised as Force Magnitude Force duration Force Type Force Direction OCCLUSAL FORCES AND IMPLANT DESIGNS Insertion Torque Discussion e requirements for different implant designs are not comparable. The NobelActive implant requires higher insertion torque due to the large helix angle of the For each rotation, the implant advances 2.4 mm Occlusal Forces and Implant Design and strain cause crestal bone loss and decrease long term survival of implant. Force applied to dental implants may be characterised as OCCLUSAL FORCES AND IMPLANT DESIGNS e requirements for different implant designs are not comparable. The NobelActive implant requires higher insertion torque due to the large helix angle of the and strain cause crestal bone loss and decrease long term survival of implant.
- 27. Force magnitude Average forcesof mastication vary from 10lb to 350lb Molars 200lb Canine100lb Incisors 25-35lb Parafunction as high as 1000lb Occlusal Forces and Implant Design Force Duration Normally teeth are loaded during swallowing and eating which is less than 30 min /day Bruxism increases duration to several hrs a day Occlusal Forces and Implant Design Force Type Compression, tension and shear Bone is strongest under compression ,35% weaker under tension and 65% weaker when loaded in shear Occlusal Forces and Implant Design Force Direction Implant that is angled receives increased amount of shear loads especially in the crestal region. Angled implant will also receives more stress on the overall implant system with increased risk of abutment screw loosening and and fatigue fractures of the implant or its components. Occlusal Forces and Implant Design Force Magnification Occurs when the stress is increased beyond the usual conditions of load. Cantilevered prosthesis Crown height ratio greater than normal Parafunction IMPLANT SIZE AND DIAMETER Short vs long implants: To obtain predictable success in situations with most patient force factors or bone densities, there is minimum implant length, depending on the implant body
- 28. width and theimplant design. After the ideal treatment plan determines the key implant positions and implant number, the implant length selected for most treatment plan options is at least 12 mm long. Wide vs narrow implants :The logical method to increase functional surface area is to increase the implant diameter , because the opposing landmarks limit the implant length. Wider root form designs exhibit a greater area of bone contact than narrow implants of similar design, in part from an increase in circumferential bone contact. SHORT VS LONG IMPLANTS DISADVANTAGES Studies show success with implant lengths of at least 10-15mm in lengths Implants 10mm and smaller had increased failure rates.( 10% vs 3%) Failures of short implants occurred after prosthetic loading and especially in the posterior region ADVANTAGES Bone grafting not required to restore alveolar ht Less risk of damage to adjacent structures and thermal insult during osteotomy Surgical ease IMPLANT SIZE:SHORT VS LONG GUIDELINES Increase diameter Splint together Decrease crown ht Decrease cantilever Increase surface area design OD vs FPD Minimise lateral forces Improve bone density
- 29. WIDE VS NARROWIMPLANTS ADVANTAGES Surgical Rescue implant Failed implant/immediate implant Tooth extraction/immediate Increased surface area Compensate unfavourable patient force factors Enhance surface for short implants Compensate for poor bone density Minimise loads for angled implants/cantilevers DISADVANTAGES Bone trauma because of extended drill sequence Decreased facial thickness may lead to recession Stress shielding Increased surgical failure rate Too close to adjacent tooth ,PDL encroachment Selecting an Implant System Training Budget Established company Versatility of System Mentorship Warranty
- 30. THANK YOU Suggested references: BranemarkPI,Hansson BO,Adell R, Briene U,Lindstorm J,Hallen O,et al.(1997).Osseoitegrated implants in the treatment of the edentulous jaw,experience from a 10yr period.Scand J Plast.Reconstr Surg 16:1-132 Goldberg NI,Gershkoff A (1949),The implant lower denture.Dental digest 55 :490-494 Subperiosteal implants,H Beddis,S Lello,J Cunliffe &P Coulthard BDJ 212,4(2012)Published online:13jan 2012,doi;10.1038/sj;bdj:2012:6 Small IA, Misiek D(1986),Asixteen year evaluation of the mandibular staple bone plate.J. Oral Maxillofac. Surg. 44:60-66 Dahl G,History of intramuscular inserts.J Oral Implantol 1991;17(4):440 Becker J, Ferrari D, Herten M, Kirsch A, Schaer A, Schwartz F, Influence of platform switching on crestal bone changes at non submerged titanium implants :A histomorphometrical study in dogs.J Clin Periodontal 2007;34:1089-1096. Vigolo P, Givani A, Platform switched restorations on wide diameter implants;a 5yr clinical prospective study.Int J Oral Maxillof Implants 2009;24:103-109. Fickl S, Zuhr O, Stein JM, Hurzeler MB.Periimplant bone level around implants with platform switched abutments .Int J Oral Maxillofac.implants 2010;25:577-581 Berenznai et al,2003, Glauser R , Zembic A, Rahstaller P,Windisch S.Five year results of implants with an oxidized surface placed predominantly in soft quality bone and subjected to immediate occlusal loading.J Prosthet.Dent.2007;97(suppl):559-568.