Evolution of Straight wire appliance, transition from Edgewise & Bracket placement.
www.indiandentalacademy.com
INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com
www.indiandentalacademy.com
Introduction Introduced – 1970. “sophisticated edgewise appliance”. It seeks to build as much treatment in the appliance as practical.
www.indiandentalacademy.com
Evolution of the bracket. Edgewise Appliance: Angle’s - edgewise appliance - place the teeth according to - ‘line of occlusion’. metal bracket - rectangular slot- 0.022 x 0.028”. Original soft gold bracket - easily deformed by the forces of occlusion & ligature wires The original design - modified - slightly larger bracket- tying area under the wings. www.indiandentalacademy.com
Single Width Bracket : narrow width - ineffective tooth rotation. Angle, - gold eyelets on the orthodontic bands. Two brackets-single tooth.
Twin Brackets : two edgewise brackets on a common base. ‘Siamese twin bracket’ by Swain Space between two brackets - 0.050 inch = width of one bracket. www.indiandentalacademy.com
The bases - curved to conform - curvatures of the canines &PM. some deflection of the bracket from the basepresent –controlled to a great extent . This bracket offers ‘positive control’ on the tooth . Disadvantage. Interbracket span is greatly reduced causing decrease in resiliency of wires .
www.indiandentalacademy.com
ď ąLewis Bracket : Lewis soldered auxiliary rotation arms. abutted against the bracket itself - lever arm -deflect the archwire and rotate the tooth.
ď ąVertical Slot Lewis Bracket : A vertical slot 0.020 x 0.020 inch. Uprighting springs - correct axial inclinations www.indiandentalacademy.com
Steiner Bracket : Flexible rotation arm. The flexibility - arms - a rotational effect .
Broussard Bracket : Graffard Broussard – 0.0185 x 0.046 inch vertical slot – accept a doubled 0.018 inch auxiliary wire www.indiandentalacademy.com
Later modifications: Burstone modified canine bracket a vertical tube - retraction assemblies. Edgelock Bracket and Hanson Speed Appliance Bracket : These brackets eliminate the need for ligature ties as they possess self ligating mechanism. www.indiandentalacademy.com
Holdaway - 1952 angulated brackets on the teeth adjacent to extraction spaces: aid in paralleling the roots . setting up posterior anchorage. obtaining correct axial inclinations or ‘artistic positioning’ of the teeth.
John J. Stifter -1958 U.S. patent - designing an edgewise bracket comprising a male and female component www.indiandentalacademy.com
Female part - attached to the tooth. Many interchangeable male components – various - inclination , angulation and prominence. First edgewise bracket - guidance into all three planes of space . did not address optimal tooth position & too many separate parts - needed . www.indiandentalacademy.com
Ivan Lee -1960: Torqued slots - regional and basic edgewise bracket. to eliminate - adding torque - anterior portion of the upper archwire.
Manufacturers – 1960: raised the base of lateral incisors. Raised bases eliminated the need for lateral offset bends. Jaraback – 1963: described the use of torqued brackets www.indiandentalacademy.com
Andrews Straight Wire Appliance - 1970. two varieties . The standard prescription for non extraction cases & ‘Translation series’ for extraction cases .
Roth -1976: bracket set up containing modifications of tip , torque and rotations. purpose of Roth - over corrected tooth positioning. appliance in position - impossible to position the teeth precisely into occlusion. After appliance removal – the teeth will shift slightly. www.indiandentalacademy.com
Alexander – 1983 : Vari – simplex discipline . Vari - variety of bracket types used ; simplex - KISS principle. ( Keep it Simple Sir ) Discipline was chosen rather than the appliance.
Creekmore -1993: slot machine . Slot machine - solution to the inaccuracies of bracket placement , anatomic and biologic variations ,
www.indiandentalacademy.com
over correction for tissue rebound and relapse and mechanical differences of preadjusted edgewise orthodontic appliance
It orients - archwire slot - relative to the facial surface of each tooth on the model . Craig Andreiko – 1994: Elan and Orthos system . Represent for the first time the modern CAD / CAM ( Computer aided design / computer aided manufacture ) technology . www.indiandentalacademy.com
Straight wire appliance – 1970 – Lawrence F Andrews. Origin of appl. & Six keys – interrelated. Series of five studies. 1st – 1960 – examination of post trt. dental casts – asses state of art – static occl. 2nd – 1964 – casts of dentitions – naturally occuring optimal occl. 120 samples – collected. Never subjected to ortho trt. Aligned & pleasing Excelent occlsn. Would not benefit from ortho trt. www.indiandentalacademy.com
3rd – most imp step fully programmed appl. Discovery – six keys to optimal occlsn. 4th – measurements – crown in 120 cast sample. - supply data – consistency – shape & position of each tooth type consistency – relative size – within an arch. Help in design – new appl. www.indiandentalacademy.com
5th study – established need – for fully programmed appl. 1150 – post trt. dental casts – compared – non orthodontic sample – occlusal characteristics. www.indiandentalacademy.com
Andrews – Non Programmed appliance & Fully programmed appliance. Non Programmed Appliance: Set of br. - same design for all tooth types. wire bending - achieve optimal posn. – individual tooth. Fully Programmed appliance: Set of br. – guide teeth – goal posn. – unbent archwires. www.indiandentalacademy.com
Non Programmed Appliance: Design short comings. Six factors.Each factor – Slot misdirected > 2°, optimal angulation & inclination. > 0.5 mm occluso gingivally, Mesio distally, Facio lingually. www.indiandentalacademy.com
Factors are: Br. Base perpendicular to br. Stem.. Br. Base not contoured occluso gingivally. Slots are not angulated. Br. Stem – equal facio lingual thickness. Max. molar offset not built in. Bracket siting tech. – unsatisfactory. www.indiandentalacademy.com
Perpendicular bases. Base per. – F-L axis of stem. Each crown – its own optimal inclination. Br. When sited – base point to FA point of each crown – target slots – that many difft. inclinations & occluso gingival levels
www.indiandentalacademy.com
Bases not contoured occluso gingivally: Br. Unintentionally rocked – occl. Or gingivally. Potential inclination range - > 2° Occluso gingival range - > 0.5mm.
www.indiandentalacademy.com
ď ą Mesio distal contour: Partly contoured base
Flat base
www.indiandentalacademy.com
Slots not angulated. When located on FACC’s & FA points of optimally positioned crowns – slot angulations & Occl – gingival posn. – not harmonious with Andrews plane. www.indiandentalacademy.com
To correct angulation – 2nd order bends requd. To eliminate bends – angulate br. It
incln.& occluso gingival range – slot
siting.
www.indiandentalacademy.com
Stems of Equal prominence. Dist. From br. Base – centre of slot – same in each br. Slots & teeth – irregular in facial prominence – teeth are optimally positioned. Edgewise www.indiandentalacademy.com
SWA
Max. molar offset not built in. mid sagittal planes – crowns & slots – not coincidental for max. molars. MB cusp – prominent facially. So Mid sagittal plane of stem & slot – angular to mid sagittal plane of crown. www.indiandentalacademy.com
Fully programmed standard bracket. Concept of programming tooth guidance into br. based on – extensive similarities – Morphology – normal tooth types. In posns. – optimal occlusion. www.indiandentalacademy.com
Design – emanates – slot site. Slot site – “the area that the bracket slot must occupy if it is to passively receive a full size and unbent archwire when a tooth is optimally positioned.”
Fully programmed std. Br. Include: Slot siting features. Convenience features. Auxiliary features. www.indiandentalacademy.com
Slot siting features – explained from perspective – planes of individual teeth & br. Mid transverse plane. Separates crowns occl. half form gingival half. It should coincide with MT plane – slot.
www.indiandentalacademy.com
To achieve this – Feature 1: MT plane of slot, stem & crown same. Feature 2: base of br.- same inclination – facial plane of crown – FA point.
www.indiandentalacademy.com
Feature 3: Inclined base – contoured occlusogingivally – curvature of the crown. These three eliminate the need for: 2nd order bends – occluso-gingival disharmony. 3rd order bends – inclination.
www.indiandentalacademy.com
Midsagittal plane. Midsagittal plane of each slot – facial extension of crowns – mid sagittal plane. To achieve this: Feature 4; Midsagittal plane of the slot, stem of the crown same.
www.indiandentalacademy.com
Feature 5: Plane of br. Base – base point – identical to the facial plane of crown at FA point. In max. molars – 100. In all other teeth – 90 to mid sag. Plane
www.indiandentalacademy.com
Feature 6: Base of each br. – contoure to match – Md radius of area of crown – designed to fit. Feature 7. Vertical components ( Mesial & distal borders of br. Stem & tie wings) – designed to parallel one another. Horizontal components – When sited equidistant – gingiva & cusp tip –Base point – mate with crowns FA point. www.indiandentalacademy.com
Midfacial plane: Of each slot – must superimpose – crowns prominence plane. Feature 8. In an arch – all slot points – same dist. – from crowns embrasure line.
Convenience features. A design feature – facilitates – use by orthodontist or promotes comfort for the Patient – does not contribute to biological aspect of trt. Or targeting the slot. www.indiandentalacademy.com
Machining procedures – not suitable. Complex design – casting & molding – practical manufacturing process. Gingival tie wings – post. Br.- extend farther laterally – easier ligation & eliminates gingival impingement. www.indiandentalacademy.com
Facial surfaces – incisor & canine br. – designed to // their bases – in turn // crowns’ faces. – lip comfort. Mand. Incisor br. – least occlusofacial prominence.-
occl. Interference.
Br. Identification.
www.indiandentalacademy.com
ď ą Gingival wings of posterior brackets, in SWA, are stepped out. Results: easier ligation and less frequent www.indiandentalacademy.com gingival impingement.
ď ąAuxiliary features. Contribute to biologic aspects of trt.Power arms, hooks, facebow tubes, utility tubes & rotation wings. Incisor brackets: Inclination range > for other teeth. Three std. Br. – difft. Base inclination. Used according to anticipated jaw relation: Class I, Class II or Class III. www.indiandentalacademy.com
Posterior brackets: Except for max. molars – 1 br . Type needed. Max. molars - 2 br. Class I & Class II.
www.indiandentalacademy.com
Fully programmed translation brackets: When teeth require bodily movt. Addnl. Qualities : Power arm. Slot siting features: Counter mesiodistal tip & Counter rotation. Counter B-L tip – max. molars.
www.indiandentalacademy.com
Translation problems: Br – occlusal – centre of resistance. Tooth – tiphorizontal centre of rotn. – mesial or distal force. Br.- lateral – CR. Tooth – rotate – vertical center rotn.MD force. www.indiandentalacademy.com
Slot siting features: Counter rotation: Rotating the slot – 3 sp. Amounts – vertical axis ( 2, 4 or 6°). Efficient force transfer – br. slot – centre of crown – MD length of br. = dist. from slot point – tooth’s vertical axis. Rationale – farther tooth moved – greater rotation overcorrection needed. www.indiandentalacademy.com
Counter mesiodistal tip. Rotating the slot – 3 sp. Amounts ( 2,3, 4°) Counter moment – angulated slot & flexed archwire - < moment – force applied. For translation – lever long as the dist. from the slot point to the centre of Res. Power arm added. www.indiandentalacademy.com
SWA - mini
SWA - std
SWA - medium
SWA - maximum
www.indiandentalacademy.com
Optimal power arm length = dist. form bracket – C.R minus MD slot length. Power arm - gingival tie wing – side of intended direction of movement. Power arm – Calvin Case.
Counter Bucco lingual tip. Rotating – base of br.- mesio distal axis. needed – max. molar translational br. More –ve base inclination – std. br. www.indiandentalacademy.com
Translation br. Categories. Min. Translation br. 2mm or less transln. 2° of counter mesiodistal tip & power arm – distogingival tie wing – distal transln. Mesial transln. - 2° 2° - counter rotn. – direcn. of movt., 4° BL tip Medium translation br. Transln – 2-4 mm. Power arm, 3° counter MD tip +/-, 4° counter rotn, 5° counter BL tip. www.indiandentalacademy.com
Max. Translation br. > 4mm transln. 4° counter MD tip, 6° - counter rotn., 6° of counter BL tip.
Identification: All trans. Br. – 1,2 or 3 notches – occl. surface – base. Molar – 1,2 or 3 raised dots – power arms. 1 – min, 2- medium; 3 – max.
www.indiandentalacademy.com
Set of ant. br.
www.indiandentalacademy.com
List of SWA brackets.
www.indiandentalacademy.com
Roth Prescription: Standard Straight-Wire brackets – treat only nonextraction cases. Andrews - different series and sets of brackets - different combinations of extractions, -ANB differentials, & -anchorage requirements. inventory - becoming a problem Roth - prescription for a special set of overcorrection brackets - applicable to most cases. www.indiandentalacademy.com
Problems Roth noticed: achieve desired tooth positions - standard SWA, - mechanotherapy phase of treatment – compensating curves – upper & - reverse curves - lower archwires. anchorage control, - extraction cases, mesial inclination - in the buccal segments segments drift mesially during treatment. Teeth posn.- end of the appliance therapy settle into non-orthodontic normal positions www.indiandentalacademy.com
This was the beginning of the Roth Prescription. Roth’s reasoning: use primarily one prescription - finish to an "end of appliance therapy" goal tooth positions are slightly overcorrected & teeth - settle into non-orthodontic normal positions.
Overcorrection overcorrection - comprehensive prescription using - Andrews extraction brackets. www.indiandentalacademy.com
Roth’s observations: single prescription with overcorrection in all planes of space & Meet - "Six Keys to Normal Occlusion" Avoid offset bends into archwires— finishing with full-size wires – only arch form bent & flat - curve of Spee or compensating bends.
www.indiandentalacademy.com
Maxillary prescription: maxillary incisors- extra torque (5° more than normal). upper canines - less negative torque. 2° more distal tip, because - retracted in most treatment. 2° rotation to the mesial. "Super Torque" - maxillary anteriors - Class II, division 2
www.indiandentalacademy.com
buccal segments - distally uprighted to 0°, the bicuspids- rotated 2° mesially, molars -14° distal rotation (2x, > nonorthodontic normals) & 14° buccal root torque (5° more than normal). www.indiandentalacademy.com
Mandibular prescription: Incisor brackets - same - non-orthodontic normals Canines - 7° mesial tip and 2° distal rotation. Lower buccal segment - 3° distal tip & 4° distal rotation. necessitate extra distal rotation. buccal segments - torque - normal, (overcorrection to problems and interferences) Two lower molars -the same degree of root torque www.indiandentalacademy.com
Root Positions Root positions of a set of extracted teeth – Roth Prescription - overcorrection in appliance & in arch form. Overcorrection - extracted teeth –never expressed intraorally www.indiandentalacademy.com
Roth prescription
Andrews prescription
www.indiandentalacademy.com
Reasons: Angle of deflection – b/w- bracket slot & the archwire. force values drop low – below threshold. The teeth - relapse back to their original positions. Need to build in offsets - undesirable side effects of tooth-moving mechanics. www.indiandentalacademy.com
www.indiandentalacademy.com
www.indiandentalacademy.com
Thank you www.indiandentalacademy.com Leader in continuing dental education
www.indiandentalacademy.com