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Orthodontic Miniscrew Implants Dr. Zaid Al-Dewachi • • • • • • • • • • History of skeletal anchorage Biological basis of mini-implant anchorage Types of Temporary Anchorage Devices (TAD) Advantages of using TADs Treatment planning for Miniscrew Implant (MI) placement Selection of a MI system Things to consider before placing a MI Insertion technique Biomechanical consideration using MI Uses of MI in difficult anchorage situations History of Skeletal Anchorage • 1945 - Gainsforth and Higley - concept of skeletal anchorage using vitallium implants • 1969 - Branemark - concept of osseointegration using titanium implants • 1985 - Kokich – concept of purposely induced ankylosis of a deciduous tooth • 1990’s – Commercially available miniscrew implants • 1997 – Kanomi – K1 system of osseointegrated miniscrews Biological Basis of Miniscrew Implant Anchorage • Miniscrew implants are – Made of titanium alloy – Have a smooth machined surface – Not surface treated • Osseointegrated implants Biological Basis of Miniscrew Implant Anchorage • At the time of insertion – – – – – Devitalization of 1 mm of peri-implant bone Close bone implant contact Primary stability Local inflammatory response Bone remodeling Secondary stability Loading More bone formation Biological Basis of Miniscrew Implant Anchorage Hounsfield Classification of Bone Density • D1: Dense compact bone • D2: Dense to thick porous compact bone on the outside and coarse trabecular bone on the inside • D3: Porous compact and fine trabecular bone • D4: Fine trabecular bone • D5: Immature, non-mineralized bone D1 D2 D3 D4 Types of TADs • Osseointegrated (surface treated – need lag time) – – – – Palatal implants Onplants Retromolar implants Dental implants • Non-osseointegrated (smooth surface – immediate loading) – Miniscrew implants (MI) – Miniplates Advantages and Uses of TADs • • • • • • Patients with hypodontia Asymmetric tooth movements Treatment of occlusal cant Alternative to orthognathic surgery Retreatment cases Cases of poor patient compliance Things to Consider before Placing a MI • Patient related factors – General factors • • • • • Smoking Age Infective endocarditis Diabetes mellitus Bone diseases and use of medicines – Local factors • Oral hygiene • Quality bone • Tooth roots and other vital structures Things to Consider before Placing a MI • Reducing the risk of complications Bittencourt LP, Vasconcellos M, Mucha J. The optimal position for insertion of orthodontic miniscrews. Rev Odonto Cienc. 2011; 26 (2): 133-138. Things to Consider before Placing a MI • Biomechanical utilization – – – – Force vector Magnitude of force/torque Force vs couple Direction of tooth movement Selection of a MI System • Design characteristics – – – – – – Pitch – tight vs loose Length – 6 – 10 mm Diameter – 1.3 – 2 mm Shape – Conical, cylindrical, mixed Tip – Thread forming vs thread cutting Surface – Smooth or roughened • Ease of use – Need for a pilot hole – Need for soft tissue punch – Insertion torque – insertion devices Insertion Technique • Drill-free method • Screw is placed directly in the cortical bone • Pre-drilling method • A hole of diameter smaller than the miniscrew is drilled in bone • Speed of < 30 rpm (round per minute) • Screw is inserted with less insertion torque • Pilot drilling method • A small round / fissure bur is used • Secure initial penetration of drill-free implants Insertion Technique • • • • • Rinse with a 0.12% chlorhexidine solution Apply a topical anesthetic gel Anesthesia with 2% lidocaine with epinephrine Quarter of a single 1.8 ml ampule is sufficient Will not completely anesthetize the PDL Insertion Technique • Determine the site by placing a probe parallel to the long axis of the teeth or a radiograph • Pinpoint mark is made at the planned area with explorer • Miniscrew is mounted on driver and secured on cortical bone • Clockwise roations at less than 1/4 rotation per second • Detach driver from screw by pulling in the axis of the screw • Primary stability – Periotest scores (-3 to 10) Biomechanical Consideration using MI • • • • Loading Time Loading Technique Loading Force Loading Torque - Immediate - Direct vs Indirect - 300gm - 11000 gm/mm Uses of MI in Difficult Anchorage Situations • • • • • • • Intrusion of upper or lower anterior teeth Intrusion of upper posterior teeth Mesialization of molars Correction of crossbite Distalization of molars Retraction of anterior teeth Use of MI with functional appliances Intrusion of Upper or Lower Anterior Teeth • Force system for enmass intrusion of upper anterior teeth Intrusion of Upper or Lower Anterior Teeth • Force system for enmass intrusion of upper anterior teeth Intrusion of Upper Posterior Teeth • Intrusion of supra erupted upper posterior tooth/teeth Intrusion of Upper Posterior Teeth • Intrusion of posterior teeth Intrusion of Upper Posterior Teeth • Intrusion of posterior teeth Mesialization of Molars Mesialization of Molars Correction of Crossbite Villela HM, Santos Sampaio AL, Bezerra F. Use of orthodontic miniscrews in asymmetrical corrections. Dental Press J Orthod. 2008;13:107–117. Distalization of Molars • Nance button fixed with miniscrews Distalization of Molars • Pendulum appliance fixed with miniscrews Distalization of Molars • Open coil assembly fixed with miniscrews Distalization of Molars • Use of transpalatal arch with miniscrews Distalization of Molars • Use of split palatal arch with miniscrews Retraction of Anterior Teeth • Biomechanical consideration Retraction of Anterior Teeth • Use of power arm Nanda, R. Biomechanics and Esthetic Strategies in Clinical Orthodontics. St. Louis, MO: Elsevier Saunders; 2005. Retraction of Anterior Teeth • Completion of retraction – Change of force system Use of MI with Functional Appliances • Treatment of Class II malocclusion Uzuner F, Aslan BI. Miniscrew Applications in Orthodontics. In: Current Concepts in Dental Implantology. Turkyilmaz I, editor. ISBN 978-953-51-1741-4. Use of MI with Functional Appliances • Treatment of Class II malocclusion Luzi C, Luzi V, Melsen B. Mini-implants and the efficiency of Herbst treatment: a preliminary study. Prog Orthod. 2013 Jul 31;14:21. Use of MI with Functional Appliances • Treatment of Class III malocclusion Thank You!