INTRODUCTION TO FIXED APPLIANCE.
Appliances that are fixed or fitted onto to the teeth by the operator & cannot be removed by the patient at will are called fixed appliance.
Advantages: Can do complex tooth movement Better control over tooth movement Better control of anchorage & extraoral force can be used in conjunction with fixed Eg: Head gears.
Doesnot require pt co-operation Better aligning, detailing & finishing of the occlusion Disadvantages: Difficult to maintain good oral hygiene More time consuming to fix & adjust More conspicous and not esthetically pleasing Requires special training of the operator Patient visit the orthodontist at regular intervals Comparatively expensive
Various tooth movement brought about by fixed appliances: Tipping Bodily movement Torquing Uprighting Rotations Extrusion & Intrusion
Tipping:- Here the crown moves in the direction of force around a fulcrum in the apical region of the root. Root apex moves in opposite direction. Bodily movement:- Equal movement of both the crowns as well as the root in the same direction.
Torquing:- Root movement in the labial or lingual direction Uprighting:- refers to mesio-distal movement of the roots.
Extrusion & Intrusion:- refer to Vertical movements of teeth along their long axis.
History: The irregular position of teeth has been a problem for some individuals since the beginning of time. Attempts to correct this disorder go back to at least 1000BC.
1850 AD:- The first texts which systematically described orthodontics appeared. Dr. Norman Kingsley was among the first to use extraoral force to correct protruding teeth. 1890's AD:- Dr. Edward Angle "The father of Modern Orthodontist'' was one of the first to emphasize occlusion in the natural dentition. His interest in creating proper occlusion in natural teeth created the specialty of orthodontist.
1900'AD:- With a concept of normal occlusion established by Angle, orthodontist began to enable into the treatment of malocclusion and not just the straightening of teeth. 1940'AD:- Cephalometerics radiographs were developed which allowed the orthodontist to see how he bones of the face contributed to malocclusion. 1970's AD:- Surgical technique developed which allowed oral surgeons to perform surgery on patients who did not have the ability to grow any longer.
PRESENT ORTHODOMTICS: Uses a combination of extraoral forces to align teeth as well as growth modification, surgery and extractions to accomplish 3 goals. Create the best occlusal relationship Create acceptable facial esthetics Create a stable occlusal result DIFFERENT TECHNIQUES: The edgewise arch mechanism was Edward.H.Angles last and greatest contribution to orthodontics. The edgewise mechanism was designed to allow the orthodontist to place the teeth into Angles concept of the 'line' of occlusion' defined as ''the line with which in form and position according to type, the teeth must be in harmony if in normal occlusion.'' The evolution of this appliance and its recommended use can be traced by following Angle's earlier works in appliance design.
ANGLE E Arch: The simple E.ARCH which was used primarily for tipping tooth crowns into proper alignment, was the first in a long series of Angle appliances. It was the first to utilize stationary anchorage or bodily control of first permanent molar teeth, which were fitted with clamp bands. The expansion arch was threaded to form a traction screw arrangement attached to the buccal of the anchor bands.
The shortcomings of this approach became apparent to Angle and he set about to device a means for more individual tooth control. The pin and tube appliance by which the tooth roots could be brought into proper axial relationship with the crowns was a logical consquence. This was the first appliance developed by angle that employed a bracket and used bands on most of teeth. However despite it potential versatility, difficulties were encountered with the actual manipulation of the technique. Noyes commented that the pin and tube appliance demanded such a high degree to skill to obtain proper parallelism b/w the tubes & pins on the archwire that few would be able to master the technique. Soldering & unsoldering the pins at each adjustment was time consuming and tedious. The appliance design made rotational adjustments most difficult
RIBBON ARCH APPLIANCE The ribbon arch appliance introduced in 1915, was the next step in the evolution of took alignment devices. It was actually the first bracket as such to be used in an orthodontic appliance. It obviously was a great step forward and in fact was a testament to the genius of Angle insofar as the light wire technique of P. Raymound Begg of Australia was built around this bracket. Begg and his co-workers modified it only slightly. Both the Begg technique and the ribbon arch technique require a locking pin for attachment of the archwire to the bracket. One of the main advantages of the ribbon arch appliance is that it alones rotations to be readily accomplished. It also offers control of buccolingual and labiolingual movements and both incisogingival and occlusogingival movements are possible. The primary short using of the ribbon arch appliance as originally developed was that it made mesiodistal axial movements difficult to obtain. This inability to achieve distal tipping movements of buccal segments proved to be a serious handicap. Experience showed, furthermore that the size of the ribbon arch itself did not provide the stability thought necessary for stabilization or anchorage of the posterior teeth. It should be noted that the original ribbon arch technique , as developed by angle, was non-extraction oriented, in contradistinction to the current usage of the ribbon arch bracket in the Begg technique for both extraction and non-extraction treatment.
To overcome the deficiency of ribbon arch Angle re-oriented the slot from vertical to horizontal and inserted a rectangular wire, rotated 900 to the orientation it had with ribbon arch thus the name edge wise.
Preajusted edge wire (straight wire) – tip and torque pre adjusted into wire.
Raymond Begg received his training in orthodontics from Angle school during the early 1900's the later returned to Australia in 1925 and practised the edgewise technique. In the mean time Begg modified the Angle's ribbon arch technique & introduced the Begg light wire differential force technique. This appliance used the concept of differential force and tipping of teeth rather than bodily movement. Begg appliance used high strength stainless steel wire along with a number of auxillaries and springs to achieve the desired tooth movement. Treatment using Begg appliance is carried out in 3 different stages. Stage one Stage two - concerned with alignment, correction of crowding, rotation correction, closure of anterior space and achieving an edge – edge anterior bite .
- Remaining extraction spaces are closed while maintaining the previous corrections that have been achieved. Final Stage - Uprighting and torquing is carried out to achieve normal axial inclination of teeth.
The straight wire technique is a recent modification of the edgewise appliance introduced by L.F.Andrews in the 1970's, based on his 6 keys to normal occlusion. The basic concept was to programme the bracket to have the first, second and third order components so that the wire need not have any complex bending as required in edgewise appliance.Hence it is called Preadjusted Edgewise Appliance. This technique made it possible to substantially reduce the wire bending required and also enabled good finishing of cases.
The lingual orthodontic technique was introduced in 1976 by Craven Kurz. In this technique the brackets are placed on the palatal & lingual aspects of the teeth. Both the edgewise and Begg principles can be employed in treatment. Lingual appliances are highly esthetic but have the disadvantage of poor access and difficulty in speech and maintaining the oral hygiene.
The origin of orthodontic bonding dates to 1955 with the publication of the original work by Buonocore who demonstrated improved retention of methyl methacrylate resins to enamel after 30sec application of 85% orthophosphoric acid. In 1965 Newman reported on the use of epoxy adhesives for the bonding of orthodontic attachments to teeth. He was the first to use the acid etch technique for this purpose. The last major development was by Bowens who developed a bisGMA resin that proved to the more stable than the previous resins. Currently available bonding resins are based on Bowen's bisGMA resin. .
Advantage: More esthetically acceptable.
Easier oral hygiene maintenance. Partially erupted teeth can also be bonded. Risk of caries is eliminated.
Proximal stripping is possible. Less chair side time.
Proximal areas are available for restoration.
Disadvantage: It is a weak attachment Risk of enamel demineralization Enamel fracture can occur during debonding More boding failure
Types: Direct Bonding Indirect Bonding Steps: Polish the teeth with pumice powder to remove pellicle. Etching 35-50% of buffered orthophosphoric acid for 30 – 50sec.
Wash the etchant We can visudisc a frosty white appearance Apply sealent on the tooth surface.
Hold the bracket in reverse tweezer, apply sealant and adhesive over the bracket and selfcure or light cure it.
Position the bracket and press to remove the excess material which has to be removed to avoid white spots on tooth.
After sometime apply arch wire
Banding involves the use of thin stainless steel strips called bands that are pinched tightly around the teeth and then cemented to the teeth. The stainless steel tape is available in different width and thickness to suit different teeth. While the molar band material is wider and stiffer, the anterior band material is relatively thinner and narrower in width. The outer surface of the band material is smooth and glassy while the inner surface is comparatively rough and dull, so as to aid in retention of the cement.
Indications for banding In cases of posterior teeth banded attachments resists occlusal forces. It is preferable to band a tooth that requires buccal as well as lingual attachments. Band are better likely to resist heavy forces, head gears. Although it is possible the band attachments these cases.
It is preferable to use banded attachments
Steps in banding Separation of teeth Tight contacts should be broken using tooth separators prior to band pinching.
Different type of separators used are: Ring separator Dumbbell separator Brass wire separator Keslings spring separator.
Selection of band material Pinching of the band using a band pinching pliers, the band is tightly drawn around the tooth to form a ring. The bent portion is spot welded and the gingival margins of the bank are trimmed to conform to the contour of the gingival margin Fixing the attachment.
Attachments include brackets for the anterior teeth and buccal or molar tubes for the posterior teeth.
Cementation of the band.
During cementation, adequate moisture control is necessary by means of saliva ejectors and cotton roles. Cements used are zincpolycarboxylate, zincphosphate, glass ionomer cement etc.
COMPONENTS ACTIVE COMPONENTS Arch wires Springs Elastics Separators PASSIVE COMENTS Bands Brackets Buccal Tubes Lingual Attachments Lock pins Ligature wire ARCH WIRES: They can bring about various tooth movements through the medium of brackets and buccal tubes which act as handles on the teeth.
Ideal Requirements Spring back:- measures how far a wire can be deflected with out causing permanent deformation. Stiffness: Formability:- Wires exhibit high formability so as to bend the arch wires into disired configuration as coils,loops etc. Resilience:- The amount of force the wire can withstand before permanent deformation.
Bicompatibility environmental stability Joinability Friction Classification of arch wire I Based on material used Gold and Gold allays Stainless steel Nickel titanium alloys Beta titanium Cobalt chromium nickel alloys Optiflex arch wires.
II Based on cross section Round Square Rectangular Multiistranded.
Gold & gold alloys :- Prior to 1940, gold was extensively used in the manufacture of orthodontic wire.
Stainless Steel:- Austenitic stainless steel referred to as 18/8 is used to make orthodontic arch wire. Nickel Titanium alloys:- (Nitinol) have super elasticity and but reduced formability and cannot be soldered or welded. Beta:- titanium:- (T.M.A wires) Cobalt chromium nickel alloy(Elgiloy) Optiflex arch wires:- made of clear optical fibers and are highly esthetic with high resilience Multithreaded arch wires:- can be trusted or coaxial in form and have increased flexibility.
Begg called it as engine of appliance, made up of latex rubber.
Types: Class I – Molar to canine (intraarch) Class II – lower molar to upper canine Class III upper molar to lower canine Box elastic – to correct antr open bite Cross elastic – used in begg's appliaice Transpalatal elastic – to correct molar crossbite Elastic chains – Available as long chains if interconnected rings used in closure of space Elastic thread – made up if corex of latex rubber and surrounded by a sleave of woven silk used to derotate of tooth.
Elastic Modules – Made of 2 elastic rings separated to close space and for derotation of teeth Ligating ring's – Archwires can be secured to the brockets using small electrometric rings called lighting rings.
Uprighting springs : Used to move root is a mesial or distal direction Torquing Springs : Move root in a lingual or palatal creation Open coil springs : Compressed b/o two teeth to open up space b/o them.
Closed coil springs : stretched b/w teeth to close space
BANDS The attachment like brackets and molar tubes are soldered or welded over these bands which are cemented in position around the teeth.
Band sizes Incisor Canine Premolar 0.150
Molar thickness width (inches) 0.003
Act as handless the transmit the force from the active components to the teeth. Brackets have one or more slots that accept the arch wire.
Edgwise type of brackets Has horizontal slot facing labially. Also called as rectangular slots as they accept wires of rectangular cross section with larger dimension being horizontal
Ribbon arch brackets:
Has vertical slot facing the Occlusal or gingival direction. Slot is narrow m-d and are used in begg fixed appliance.
Weldable and bondable brackets Brackets that are bonded directly over the enamel and those that are weldable or soldered over the bands.
Metallic brackets Can be recycled and sterilized, resist deformation and fracture.But unesthetic and cause staining of teeth.
Ceramic brackets Are dimensionally stable and do not distort in oral cavity but are brittle and fracture.
Plastic brackets: Available in tooth coloured or transparent forms but undergo discoloration and their slots tend to distort.
Buccal Tubes: Can be round or rectangular in cross section. May have sometimes double or triple tubes. These additional tubes are for additional arch wires and for face bow insertion.
Are fixed on lingual aspect and are required for engaging elastics Eg: lingual buttons Lingal cleats, Eyelets Ball end look
Are soft stainless steel wires of 0.009-0.011 inches diameter and are used to secure the arch wire to the brackets usually necessary in edgewise type of brackets. Lock pins: Used to secure the arch wire to brackets with vertical slots such as ribbon arch brackets and usually made of brass.
Conclusion Fixed appliance is thus an extragenous method to correct both skeletal and dental malocclusion but though being uncomfortable to patient can bring esthetic and functional satisfaction. Reference: GRABER Google.com