Characteristic anterior tooth movements in stage I
Labiolingual movements as required for alignment on the anterior curve of the archwire
Over rotating - To positions that are reverse of the original rotation
Creating space for overlapped teeth or closing spaces as required ,so that the incisors and cuspid of each dental arch are placed and maintained in a single segment of six anterior teeth
Intruding the anterior teeth for correction of overbite,all 12 teeth should be intruded evenly
Retracting anterior teeth for correction of overjet and for placing them in a slightly lingual inclination.proper retraction means that the central incisor crowns tip lingually,lateral incisor crowns tip lingually and distally, and cuspid crowns tip distally
The anchor molars are maintained in upright positions throughout treatment. Specifically, mesially inclined molars are overcorrected to mild distal inclinations and distally inclined molars are maintained in mild distal inclinations. These positions are most efficient for molar anchorage requirements
Molar rotations are corrected. Mesiolingual rotations are corrected to mild mesiobuccal rotation and mesiobuccal rotations are maintained as such
Cross bite relationships are overcorrected
Chracteristic archwires and elastics in the first stage
Plain or looped archwires.looped archwires are replaced as soon as possible
In class I and class II cases,class II elastics are used. In class III, class III elastics are used
Bracket Placement: Brackets are centered mesio distally on the labial or buccal surface with the base of the arch wire slot 4mm from the incisal edge of cusp tips. Only exception is maxillary lateral incisor where 3.5mm from the incisal edge is placed.
Lingual Button: Placed directly opposite to to the areas of engagement of the archwire on the opposite side of the teeth. This is to permit free mesio distal tipping or uprighting of the teeth. If the lingual button is placed incisal or occlusal to the level of base of arch wire the steel ligature would loosen or tighten during mesio distal uprighting.
Buccal Tube: Molar tubes should be parallel to the occlusal surface when viewed from buccal and parallel with a line bisecting the occlusal surface mesiodistally.
Arch wire: Different diameters of wire are available but the most commonly used one is 0.016” wire 0.016” special plus - Looped arch wire in any case 0.016” special plus - Plain arch wire in extraction cases or in which 1 st and 2 nd premolars are extracted 0.018” - Plain arch wire in molar extraction cases Initial Arch wire: The basic shape of the initial archwire depends upon the shape of malocclusion and although it is similar it is seldom identical. The archwire shape is proportional to the width, the form and symmetry of dental arch. There may be localized modifications of archwire in the vertical and horizontal plane and these are called Offset bends.
Offset bends: In Anterior segment Vertical offset - To Intrude or Extrude Horizontal offset - to Expand, contract and rotate In posterior segment Gingival offset - to avoid occlusal distortion and interference with bicuspids
The labiolingual width of the cuspid is greater than that of the
lateral when measured at bracket level
To avoid lingual tipping of the cuspid and labial tipping of the
lateral a horizontal offset bend is given distal to the
It is usually called the cuspid offset bend,however it provides for
proper positioning of both lateral and canine
Shape of Anterior segment: The anterior curve of the initial arch wire is usually a compromise between the shape of the malocclusion and that of normal occlusion. E.g.: If anterior segment is narrow and protrusive the arch wire is made slightly broader in the cuspid region and flatter opposite to central incisors.
Used to supply local increased arch flexibility or used for space opening or closing, stops, rotation or root torque.
The most vertical loops to align six anterior teeth are five, one in each interproximal area.
Generally loops are made 6 to 8mm long but greater the length of the loop, the more gentle the force on the tooth .
The Loop between the maxillary central incisors should be avoided, when indicated the loop is made shorter because
Avoid irritation to the labial frenum
Loop in midline causes arch wire to assume “V” shape when contracted by placement in the molar tube
Horizontal bracket area for severly lingually placed tooth is bent 1mm further gingivally than plane of arch wire to prevent elongation of tooth as it tips labially Contraction Loop in midline with incisor stops to tip crowns of upper centrals Vertical loops bent in case of high frenum attachment
Placed immediately posterior to the 2 nd premolar bracket
Bent opposite so that when inserted into the buccal tubes the anterior section of the archwire lies in the buccal sulci
Amount of bend varies from case to case
Greater force tend to eventually cause lingual rolling and distal tilting of molars
Increase of excessive leverage the mesial marginal ridge of the molars are is seen to raise above the occlusal level
the purpose of anchor bend in upper arch is to prevent mesial migration of the molars; In lower is to supply bodily control of the lower molars as these are moved forward by action of Class II elastics
The anchorage bend,formerly called the tip back bend is a bend whose vertex faces occlusally
Anchorage bend opposite to molar premolar contact point Labial portion lying in buccal sulci
Inclination of the anchor molar- if one or both the molars are
inclined then the anchor bend should be reduced so that the
wire will rest evenly and passively in the mucobuccal fold
The hazard of occlusal impingement
The type of archwire used – in looped archwire it is placed far enough forward so that ythe bend does not slide back into the buccal tube before the looped archwire is discarded
Bayonet bends : Commonly used passively to retain overrotation brought about via previously looped arch. It is inadvisable to use bayonet bends for active correction, because of the tendency for round archwire to rotate within bracket slots causing the bayonet bend to become ineffective or supply movement in wrong plane They should be small and offset section is 5 degrees to the line of main arch.
In non extraction cases the class II and horizontal elastics average 1 ½ -2 ½
ounces (42-71) grams
Larger diameter elastics exert lighter force and smaller diameter exert heavier
The natural rubber Begg elastics used in the early 1960’s exerted 5-8 ounces
(142-227) gms and the elastic force was reactvated in four day cycle.
Currently, latex elastics are preferred that exert much lower force initially but
show less drop off over a 24 hour span
Placement of Elastics: It is impossible for the arch wire to function properly without the proper elastics. In order to determine the size of the elastics the tension gauge is used. The Class II elastics are engaged around the distal ends of the molar tubes or molar hooks and stretched anteriorly to engage the maxillary Intermaxillary hook mesial to the maxillary cuspid. In Class III elastics are worn from the maxillary molars to the intermaxillary hook mesial to the mandibular cuspid bracket. No horizontal (intramaxillary) elastics are applied during stage I
Class II elastics pulling 2 to 3 ounce at the beginning Class III elastics Horizontal (intramaxillay) elastic
Check for desired movements Overbite and over jet improvement Anterior alignment progressing Dental arch width particularly the molar width Dental arch form being maintained Antero - posterior relation of cuspids and molars being maintained Individual molar positions being maintained
Check for undesired movements or manifestations Failure to wear elastics at all times Poor hygiene Vertical loops impinging on tooth or tissues Arch wire distortion contraction or expansion of arch width
STAGE MODELS. THE IMPORTANCE OF STAGE MODELS AS TOLD BY DR.A ROCKE,: 1. TO CHECK THE ARCH CONTOUR AND WIDTH. 2. TO CHECK THE INCLINATION OF UPPER AND LOWER ANTERIOR TEETH. 3. SELF-DISCIPLINE TO TO COMPLETE EACH STAGE BEFORE PROCEEDING TO THE NEXT. 4. TO DETERMINE THE TEETH MOVEMENT. 5. TO GAIN INSIGHT INTO ANCHORAGE MAINTAINED IN THE TREATMENT. 6. VISUAL AID FOR PATIENTS AND PARENTS. 7. VISUAL AID FOR REFERRING DENTISTS THE POSSIBILITY OF ANTERIOR TORQUING..
Intermaxillary hooks are incorporated in both archwire immediately mesial to the cuspid brackets and in contact or very near contact with them
The hooks in upper arch has to bear two elastics which is somewhat difficult for ring pattern. A ‘Z’ shaped hook makes it easier for the patient to apply two rubbers to the hook
The 2nd premolar is bypassed from pinning as in Stage I, The wire is held in position by bypass clamp or steel ligature
The bypass clamp in position of the bracket in premolar Slight horizontal offsets are formed distal to canines to maintain correct buccolingual position of the premolars and canines-they are the premolar offsets
Passive- to prevent the rotation of anchor molars already in normal alignment
Inter & Intramaxillary elastics: Lateral Cephalogram is taken and from cephalometric evaluation it is determined whether the anteriors are to be retracted or posteriors are moved for closure of space. The Space – closing elastic ( esp. the maxillary) stretching from the Intermaxillary hook to the molar hook against molar lies against the gingiva and irritates the gingiva, to overcome this elastic is twisted one half turn when it is placed
Wearing of horizontal elastics try to rotate the molars distobuccaly and this should be counteracted by the toe – in bends of the arch wire. If rotation aggravates after giving toe in bends the elastics can be engaged on the lingual hooks. Care should be taken of the second premolar so it doesn’t tip when elastic crosses it occlusally.
Correction of Midline discrepancy: Midline must be determined by reference to the center of face, whether the discrepancy is confined to one arch or in both If one arch is involved shifts more than 2mm is major; less than 2mm is a minor problem. The application of intramaxillary elastic will complete closure on the side to which midline is shifted; The intramaxillary elastic on the side which closes first can be discontinued Minor discrepancies are self correcting Diagonal elastics for correction of midline in both the arches Correction by movement of individual units or small group after distal tipping of canine
Auxiliaries in stage II: The auxiliaries used are passive mesio distal root uprighting springs on the mandibular canines and the lower anterior braking arches. The function of of these types of auxiliaries is to establish two point contact between teeth and archwire and prevent free tipping movement of the anteriors. Lower braking auxiliary on the four Anteriors