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REMOVABLE ORTHODONTIC APPLIANCES (ROA), THEIR INDICATIONS AND CONTRAINDICATIONS by Dr. Wangui .K. Objectives • • • • • Definition of ROA Brief History of ROA Mode of Action Components of ROA Indications & Contraindications of ROA Definition: Appliances that can be inserted and removed from the mouth at will, by the patient. History • Victor Hugo early 20th century used vulcanite bases • Crozat used precious metals i.e. gold for arch expansion Action of removable appliances • Act by tipping the tooth around its centre of resistance. • Teeth that have their apex at the correct position are ideally suited for treatment with ROA. • Ineffective in bringing about bodily translation, derotation and uprighting due to the single point of contact of these appliances • Incorporation of bite planes enables intrution and extrusion of teeth COMPONENTS OF ROA • retentive components • active components • base plate Retentive Components Clasps: • Adam’s clasp • Crozat clasp • Circumferential clasp • Jackson’s clasp • South end clasp • Ball end clasp Requirements of clasps Easy to fabricate & clean • Shouldn't impinge on soft tissues • • Provide adequate retention • Deciduous and permanent dentition • No active forces causing unwanted tooth movement Active Components • Bows • Springs • Screws • elastics Bows *Uses & Examples: • Short & long labial bow • Reverse labial bow • Split labial bow • Roberts retractor-severe overjet • Mills retractor • High labial bow with apron springs Springs Requirements: • Easy to fabricate and clean • Robust • Should not be easily dislodged • Force in required magnitude and direction • Active over a long period of time • Should fit easily in available space *Uses & Examples: • • • • • Finger springs Z spring T spring Coffin Spring Canine retractors Screws Used to: • expand arch • Buccal lingual & mesio-distal tooth movement • Activated using a key Elastics • Rarely used with ROA. • used for anterior teeth retraction Base Plate dIndications of ROA Contraindications of ROA Expansion of narrow arches Severe skeletal discrepancy Treatment of Individual arches Severe rotation Bite correction Upper & lower arch correlation treatment Unilateral Crossbite Bodily movement Single malpositioned teeth Severe crowding Bad habits Very dense bone References Orthodontic Art and Science S.I Bhalajhi • Orthodontic Pearls Eliakim Mizrahi • Adams: Removable Appliances Yesterday and Today American Journal of Orthodontics1969;202-218 •