Orthodontic Miniscrew Implants
Dr. Zaid Al-DewachiHistory 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
1945 - Gainsforth and Higley - concept of skeletal anchorage using vitallium implants 1969 - Branemark - concept of osseointegration using titanium implants1985 - Kokich – concept of purposely induced ankylosis of a deciduous tooth 1990’s – Commercially available miniscrew implants1997 – Kanomi – K1 system of osseointegrated miniscrews History of Skeletal Anchorage
Biological Basis of Miniscrew Implant Anchorage
Miniscrew implants are Made of titanium alloy Have a smooth machined surface Not surface treated Osseointegrated implantsBiological Basis of Miniscrew Implant Anchorage
At the time of insertionDevitalization of 1 mm of peri-implant boneClose bone implant contact Primary stabilityLocal inflammatory response Bone remodeling Secondary stabilityLoading More bone formationBiological 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 boneD1 D2 D3 D4
Types of TADs
Osseointegrated (surface treated – need lag time)Palatal implants OnplantsRetromolar implantsDental implantsNon-osseointegrated (smooth surface – immediate loading)Miniscrew implants (MI)MiniplatesAdvantages and Uses of TADs
Patients with hypodontia Asymmetric tooth movements Treatment of occlusal cant Alternative to orthognathic surgery Retreatment cases Cases of poor patient complianceThings 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 structuresThings to Consider before Placing a MI
Reducing the risk of complicationsBittencourt 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 movementSelection of a MI System
Design characteristicsPitch – tight vs looseLength – 6 – 10 mmDiameter – 1.3 – 2 mmShape – Conical, cylindrical, mixedTip – Thread forming vs thread cuttingSurface – Smooth or roughenedEase of useNeed for a pilot holeNeed for soft tissue punchInsertion torque – insertion devicesInsertion 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 PDLInsertion Technique
Determine the site by placing a probe parallel to the long axis of the teeth or a radiographPinpoint mark is made at the planned area with explorerMiniscrew is mounted on driver and secured on cortical boneClockwise roations at less than 1/4 rotation per secondDetach driver from screw by pulling in the axis of the screwPrimary stability – Periotest scores (-3 to 10)Biomechanical Consideration using MI
Loading Time - Immediate Loading Technique - Direct vs Indirect Loading Force - 300gm Loading Torque - 11000 gm/mmUses 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 appliancesIntrusion of Upper or Lower Anterior Teeth
Force system for enmass intrusion of upper anterior teethIntrusion of Upper or Lower Anterior Teeth
Force system for enmass intrusion of upper anterior teethIntrusion of Upper Posterior Teeth
Intrusion of supra erupted upper posterior tooth/teethIntrusion of Upper Posterior Teeth
Intrusion of posterior teethIntrusion of Upper Posterior Teeth
Intrusion of posterior teethMesialization of Molars
Mesialization of MolarsCorrection 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 miniscrewsDistalization of Molars
Open coil assembly fixed with miniscrewsDistalization of Molars
Use of transpalatal arch with miniscrewsDistalization of Molars
Use of split palatal arch with miniscrewsRetraction of Anterior Teeth
Biomechanical considerationRetraction of Anterior Teeth
Use of power armNanda, R. Biomechanics and Esthetic Strategies in Clinical Orthodontics. St. Louis, MO: Elsevier Saunders; 2005.
Retraction of Anterior Teeth
Completion of retraction Change of force systemUse of MI with Functional Appliances
Treatment of Class II malocclusionUzuner 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 malocclusionLuzi C, Luzi V, Melsen B. Mini-implants and the efficiency of Herbst treatment: a preliminary study. Prog Orthod. 2013 Jul 31;14:21.