Removable appliances

1. 1 Removable appliances Removable appliances Prepared by: Prepared by: Dr Mohammed Alruby Dr Mohammed Alruby تكس كنا ينعي ابلاغ لب ملاستسلاا امئاد ينعي لا صاخشلاا ضعب هايح نم باحسنلاا قحتسي لا ئش لجا نم لاوط R Removable emovable appliances appliances Dr. Mohammed Alruby Dr. Mohammed Alruby

2. 2 History: = In early 1900, George Crozat developed a removable appliance that fabricated from precious metal and consists of: a-Effective clasp on 1st molars b-Heavy gold wire as a framework c-Lighter gold finger springs that produce desired tooth movements After that the removable appliance developed and continued in Europe but neglected in united state = in 1900, Monoblock developed by Robin and considered the forerunner of all functional appliance = in 1920, development of activator by Andreson in Norwegian Martin Schwarz in Vienna developed variety of split plate which effective in expanding the dental arches Philip Adams in Belfast modified the arrow head clasp by Schwartz into Adams Crip which become the basis of English removable appliance = in 1925 to 1965: American orthodontic based on use of fixed appliance that is unknown in Europe which all treatment done by removable = in 1960: introduction of functional appliances in American by Egil Harvold General requirements of orthodontic appliances: 1-Should be comfortable to wear and easily accepted by patients 2-Should be able to produce the desired force that cause a well-controlled tooth movement 3-Should be fabricated from bi-compatible material that is well tolerated by oral tissues 4-Should be readily cleansable by the patients so that they do not constitute a hazard to dental or oral health 5-Should be capable of being firmly positioned in the mouth Mode of action of removable appliances: There is a variety of movements can be achieved either individually or in group of teeth: 1-Tipping: unlike the fixed appliance which control the tooth in three directions, force by removable appliance is mediated by spring, elastic, piece of acrylic which can make one point of contact. Directions: mesial, distal, buccal, lingual 2-Overbite reduction: incorporating an anterior bite plate to correct the deep bite by allowing super eruption of posterior segment 3-Anterior cross bite: if space available, anterior teeth pushed by using removable appliance with spring or screw and corrected to normal bite to prevent relapse 4-Posterior cross bite: incorporated expansion screw in midline only make buccal tipping of teeth (bucally) 5-Extrusion: elastic from removable appliance used to extrude the teeth by engaging a fixed attachment by vertical component Used for impacted central incisors in mixed dentition. 6-Intrusion: by using buccal capping lead to force for intrusion 7-Retention: to maintain the position of teeth (Hawley, vacuum form) Advantages of removable appliances: Little Wood 2001: 1-Make it possible for patients to maintain oral hygiene during treatment 2-Most of malocclusion require tipping movement so removable appliance can be used 3-Less chair time side of dentist, so dentist can be handle more than one patient 4-Less force needed to move the teeth than in fixed appliances 5-Can be used by general practitioner(GP) dentist 6-Less expensive, can be used by large of people 7-Less risk of damage (root resorption) than fixed appliance R Removable emovable appliances appliances Dr. Mohammed Alruby Dr. Mohammed Alruby

3. 3 Disadvantages of removable appliances: 1-Appliance can be left out 2-Only tilting movement possible 3-Good technical required 4-Affect speech 5-In efficient of multiple tooth movement 6-Patient can misplace or damaged it 7-Patient need enough skill to remove and replaced the functional appliance without distort it Component of removable appliances: 1-Active component: -Springs -Screws -Elastics -Bows -Bite plates -ELSAA 2-Retentive component: -Adams clasp -Southend clasp -Triangular clasp -Circumferential clasp -Jackson clasp -Splint clasp -Achwarz clasp -Crozat clasp 3-Base plate 4-Anchorage Active component: Component of removable appliances that produce tooth movements 1-Springs: expression of force exerted by spring: F ∝ dr4 / B or L F: force d:deflection of spring r:radius of wire L or B: length of spring Wire length and diameter affect the force Requirement of springs: a-Simple to fabricate b-Easy to adjustable c-It should easy to clean d-Should not dislodge when placed on tooth surface e-Remain active for long period of time f-Should be robust enough Examples of springs: = Palatal finger spring: 0.05 or 0.06mm stst used for move the tooth in mesial or distal direction along the dental arch, incorporation of helix increase the length of wire and allow delivery of light force = Buccal canine retractor: 0.07mm stst wire, retract bucally placed maxillary canine = Z spring: 0.05mm stst wire used to move one or two teeth labially Activation is achieved by pulling the spring away from the base plate at a 45-degree angle = T spring: 0.05mm stst wire move the individual tooth either labially or bucally, activation by putting the spring away from the base plate. R Removable emovable appliances appliances Dr. Mohammed Alruby Dr. Mohammed Alruby

4. 4 = coffin spring: introduce by Walter Coffin. Spring provides a useful alternative to screw for expansion 1.25mm wire, activated by putting two halves of the appliance a part manually. Need good retention 2-Screws: can be embedded into the base plate of an appliance and activated by the patient turning a key. Screws make three types of tooth movements -Expansion of arch -Movement of one or group of teeth in mesial or distal, labial or buccal direction -Both 3-Elastics: Elastic force can be applied from the removable appliance Application of elastomeric force require good retention to avoid displacement 4-Bows: Active component that are used for retraction of incisors Types: a-Short labial bow: 0.07mm hard stst round, extended to the labial surface of teeth, end of U shape at distal surface of canine activated by compressing the U loops b-Long labial bow: similar to short labial bow except that extended to premolar of one side to other side and used for: -Minor anterior space closure -Minor overjet reduction -Closure of space -Guidance of canine during retraction using palatal retractor -Retaining device at the end of fixed orthodontic treatment c-Split labial bow: labial bow split in the midline used in case of diastema closure d-Reverse labial bow: here the labial loops are placed distal to canine and the free ends adapts occlusally between the 1st premolar and canine e-Roberts retractor: 0.05mm stst wire diameter, 3mm coil internal diameter that increase the wire length very thin wire used -------- high flexible wire f-Milles retractor: extended labial bow: Extensive loop spring, used in patients with large overjet, difficult in construction Poor patient acceptance due to complex design g-High labial bow with apron spring: 0.9mm wire extended into buccal vestibule Apron spring is made of 0.4mm wire attached to high labial bow, design for retraction of one or more teeth High flexible ------- light force, used in case of large overjet h-Fitted labial bow: R Removable emovable appliances appliances Dr. Mohammed Alruby Dr. Mohammed Alruby

5. 5 0.7mm adapted to follow the contour of labial surface, U loop is usually small, cannot used to bring active tooth movement, used as retainer at the completion of orthodontic therapy. I- active labial bow: can be used to reduce an increased overjet by tipping the teeth palatally High amount of wire: ----- mills. Light amount of wire: ------- Robert 5-Bite plate: Incorporation of anterior bite plane in removable appliance allow eruption of posterior to reduce deep bite. -Anterior bite plane: increased open bite, work by allowing posterior teeth to erupt and intrusion of incisors -Posterior bite plane: capping help anterior cross bite correction, distal movement of buccal segment, in conjunction with headgear to produce distal movement of maxillary buccal segment. 6-ELSAA: Expansion labial segment alignment appliance in class II cases, useful for creating overjet where your incisors either retruded or upright Retentive component Are concerned primarily with seating, it in the correct position. R Removable emovable appliances appliances Dr. Mohammed Alruby Dr. Mohammed Alruby

6. 6 a-Adams clasp: produced by Philip Adams (1950) it is known as Liverpool clasp, universal clasp, modified arrow head clasp. 0.07mm wire diameter Components: arrow head,-- retentive arms,--- bridge: made of 45-degree with long axis of the tooth Advantages: -Rigid excellent retention -Used in permanent dentition -Used in partially or complete erupted teeth -Used in premolars and molars and incisors -Small and occupied minimum space -No specialized instrument is needed Modifications: -Adams with J hooks -Single arrow head -Incorporated helix -With distal extension -With soldered buccal tube b-South end clasp: 0.7mm stst. Retention in anterior segment. c- Triangular clasp: 0.7mm stst Used between two adjacent posterior teeth Indicated when additional retention is needed d-Circumferential: = C clasp or three quarter clasp = simple clasp that are designed to engaged the bucco-cervical undercut = wire engaged from one proximal undercut along the cervical margin then carried over the occlusal embrasure to end as single retentive arm on the lingual aspect = simple and easy for fabrication = not good to use in partially erupted teeth e-Jackson clasp: = introduced by Jackson 1906, it is called U clasp or full clasp = wire adapted on the bucco-cervical margin and both proximal undercuts Advantage: simple construction, provide good retention Disadvantage: inadequate retention in partially erupted teeth f-Ball ended clasp: g-plint clasp: useful for combination of removable appliance with fixed appliance, 0.7mm stst h-Schwarz clasp: clasp designed in such a way that number of arrow head engaged the inter-proximal undercuts between molars and premolars i-Crozat clasp: clasp has an additional piece of wire soldered which engage the mesial and distal proximal undercuts *** Requirements of an ideal clasp: 1-Should offer adequate retention 2-Should permit usage in both fully erupted as well as partially erupted teeth 3-It should offer adequate retention even in the presence of shallow undercuts 4-Easy to fabricate 5-Should not impinges on the soft tissue 6-Should not interfere with normal occlusion R Removable emovable appliances appliances Dr. Mohammed Alruby Dr. Mohammed Alruby

7. 7 Base plate: Connect all component Heat cured acrylic Support anchorage through palatal coverage Can incorporated bite planes Anchorage: = for every action, there is an equal and opposite reaction (Newton’ 3rd law) = resistance to unwanted tooth movements (Proffit 1993) How can increase anchorage: 1-Clasp more teeth 2-Move only one or two teeth at time 3-Use lighter forces 4-Occlusal capping 5-Added headgear Fitting a removable appliance 1-Check acrylic for sharp edges 2-Fit appliance in patient mouth, note any rocking or areas that do not fit and adjust if necessary 3-Tighten clasp and check retention 4-Activate springs and check that teeth are free to move 5-Insure patient can insert and remove, warn of initial discomfort 6-Give written and verbal instruction to patient and parents normally removable appliance are worn 24 hours / day except sports and cleaning 7-Arrange next appointment, with patients / parents a ware to contact sooner if problem R Removable emovable appliances appliances Dr. Mohammed Alruby Dr. Mohammed Alruby

8. 8 Monitoring progress Ideally patients wearing active removable appliance should be seen around every 4 weeks, passive appliance can be seen less frequently a-The appliance shows little evidence of wear and tear b-The patient lips (aske patient count from 65 to 70 with and without appliance) c-No mark in patient mouth around the gingival margin palatally or cross the palate d-Frequent leakage At 1st review visit: 1-Is patients wearing the appliance when they attend 2-Chat to patient and note speech with appliance in place, ask about problems 3-Check appliance out of the mouth, note loss of surface luster, tooth impression on bite plane 4-Check condition of growth, palatal mucosa, should have inter-dentition or redness if good URA wear, note any trauma from spring (etc) 5-Check position of teeth that are being moved and the anchor teeth from the original study models 6-Teeth should be slightly mobile if movement is occurring. If teeth is not move, look for the causeas: -Acrylic in the way -Unerupted teeth -Retained roots -Insufficient activation 7-Reactivate spring: 1 – 2mm and tighten crib 8-Congratulate patient if appropriate and re-appointment 9-Approximately 1mm of tooth movement should occur each month Common problems during treatment (Mitchell 2007) 1-Slow rate of tooth movements: Normal tooth movement should proceed approximately 1mm / month in children and slightly less in adults If progress is slow, check the following: -If patient wear appliance full time or not, if poor cooperation, resulting in lack of progress -For spring --- is this correctly positioned and optimally activated -For screw --- if is patient adjust this correctly or not -Tooth movement obstructed by acrylic or wires -If tooth movement is prevented by occlusion with opposing arch, may be necessary to increase the bite plane or buccal capping to free the occlusion 2-Frequent breakage of the appliance: The main reason for that: -The appliance is not worn full time -Patient has a habit of clicking the appliance in and out -Patient eating food whilst wearing the appliance 3-Anchorage loss; Can increase by part time wearing appliance, and not using optimum force at optimum time 4-Palatal inflammation: Can occurred by: -Poor oral hygiene may be mixed of fungal and bacterial infection as angular cheilitis -Entrapment of gingiva between the acrylic and toot to be moved R Removable emovable appliances appliances Dr. Mohammed Alruby Dr. Mohammed Alruby