the roth prescription / orthodontic courses by indian dental academy

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Functional Occlusion&

Roth’s treatment mechanics

The Roth Prescription

INDIAN DENTAL ACADEMY

Leader in continuing dental education www.indiandentalacademy.com


Pleasing facial esthetics, evaluated by soft tissue and skeletal measurements cephalometrically.

Molar relation and tooth alignment, evaluated by Angle's description of anatomical occlusion.

TREATMENT GOALS


Functional occlusion, evaluated gnathologically on an articulator.

Stability of post-treatment tooth positions and alignment.

Comfort, efficiency, and longevity of the dentition, supporting structures, and the temporomandibular joints.

GOALS…


Roth’s :

Belief that functional dynamics of occlusion is important for stability

Functional Occlusion


The condyles should be centered transversely and seated against the articular disks at the superior and posterior slope of the articular eminences when the teeth reach maximum intercuspation,

The anterior teeth should serve as a gentle glide path to disoclude the posterior teeth but immediately upon all movement away from full closure.

Functional Occlusion


On full closure the posterior teeth should have equal & even contact of centric cusps,

The forces being directed as nearly as possible down their long axes ,

The anterior teeth should not actually be in contact but should have 0.005 inch of clearance.


Three parts -

1. On normal closure in centric relation

2. Protrusive movement

3. Lateral movement

Gnathological Objectives


Class I occlusion at centric

Simultaneous contact of all posterior teeth with force directed down the long axis of the posterior teeth

0.005” clearance of anteriors

CO = CR

On closure in centric


Mandible is not in centric when….

Occlusal wearExcessive tooth mobilityTMJ soundsLimitation of mouth openingMyofacial painTightness of mandibular musculature


Anteriors must gently disocclude posteriors

Sufficient overjet and bite

Occlusion – U- 6 anteriors with L-6 ant and 1st PMs14 teeth bear the stress

Mutually protected occlusion

Protrusive movement


Cuspids main guiding inclines

U canine cusp tips ride on disto-incisal incline of L canine.

All other teeth lifted out of occlusion

Cuspid Guidance

On Lateral Excursions


The distal surface of the distal marginal ridge of the upper 1st permanent molar contacts and occludes with the mesial surface of the mesial marginal ridge of the lower 2nd molar.

The mesio-buccal cusp of the upper 1st permanent molar falls within the groove between the mesial and middle cusps of the lower 1st permanent molar.

The mesio-lingual cusp of the upper first molar seats in the central fossa of the lower 1st molar.

Andrews Six keys of Normal Occlusion


Crown inclination is the angle between a line 90 degrees to the occlusal plane and a line tangent to the middle of the labial or buccal clinical crown.

Labiolingual crown inclination


Anterior crowns central and lateral incisors: In upper incisors the occlusal portion of the crown's labial surface is labial to the gingival portion & in all other crowns the occlusal portion of the labial or buccal surface is lingual to the gingival portion.

In the nonorthodontic normal models the average

inter-incisal crown angle is 174 degrees.

Upper posterior crowns (cuspids - molars): Lingual crown inclination is slightly more pronounced in the molars than in cuspids and bicuspids.

Lower posterior crowns (cuspids -molars): Lingual inclination progressively increases


In normally occluded teeth the gingival portion of the long axis of each crown is distal to the occlusal portion of that axis. The degree of tip varies with each tooth type.

Mesio-distal angulation


Teeth should be free of undesirable rotations.

Rotated molar or bicuspid occupies more space than normally.

A rotated incisor can occupy less space than normal.

Rotation & Tight contacts


Measured from the most prominent-cusp of lower second molar to the lower central incisor.

A deep curve of Spee results in a more confined area for the upper teeth creating spillage of upper teeth mesially and distally.

A flat curve of Spee is most receptive to normal occlusion.

A reverse curve of Spee results in excessive room for the upper teeth

Curve of Spee


Lower incisors at the cephalometric goal (+ 1 to A-Po); for facial esthetics, for planning anchorage control, and for selecting the most appropriate mechanics to reach this goal.

Tips of the upper incisors 2-2.5mm below the lip embrasure of the upper and lower lips, when the lips are closed with no lip strain.

Requirement for IDEAL occlusion


No more than 1 mm of attached gingiva showing upon a full smile.

Approximately a 2.5mm overjet-overbite

relationship at the tip of the upper incisor in its relationship to the lower incisor.

(The lower incisor would have .0005" clearance with the lingual surface of the upper incisor, but the articulating paper mark would occur 2.5mm gingival to the incisal edge of the upper incisors.)


A level or nearly level occlusal plane, at the end of appliance therapy that would return to a 1 to 1.5mm curve, at its deepest point, after appliance removal and settling of the occlusion.

A curve of Wilson that would allow seating of

centric cusps, but clearance upon excursions.


As much divergence as possible of the occlusal plane from the angle of the eminence for excursive clearance.

Lower incisors aligned contact point-to-contact point with the roots in the same plane, when observed from the occlusal, and a mesioaxial inclination of 2 degrees.


Lower cuspid crowns angulated mesially 5 degrees, with the incisal tip lmm higher than the incisal edge of the lateral incisors.

{Note :The lower cuspids should have a slightly exaggerated mesial rotation on extraction cases.}

The lower bicuspids should be uprighted 1 degree from their normal mesial inclination and should have a slight distal rotation (more so on an extraction case). The contact point should be adjacent to the contact point on the lower cuspid distal surface.


The lower molars should be uprighted 1 degree from their normal 2-degree mesial inclination and should have a slight distal rotation.

The lower buccal segment should have progressive torque close to Andrews' measurements for establishing the curve of Wilson, and there should be no rotations or spaces.


The upper six-year molars should have sufficient distal rotation, mesioaxial inclination, and buccal root torque, so as to fit with the lower six-year molars, as described by Andrews.

The same would follow for the upper second molars. The torque requirement would be what is required for the seating of the centric cusps, approximately 14 degrees torque and 0 degrees mesial inclination.


The upper bicuspids should be uprighted to 0 degrees from their normal 2-degree mesial inclination, with no rotation, except for some distal rotation in an extraction case

The upper cuspid must have its contact points adjacent to the contact points of the upper bicuspid and lateral incisor, to establish proper length for cuspid guidance. It should have 11 to 13 degrees of mesial crown tip, and mesial rotation of 4 degrees, on an extraction case..


The upper lateral and central incisors should be almost equal in incisal edge length, with no more than O.5mm height differential.

They should have 9 degrees and 5 degrees mesioaxial inclination respectively, and there should be sufficient torque so that the six upper anterior teeth can contact the six lower anterior teeth and the upper cuspids can lift off the lower bicuspids in a protrusive excursion.


There should be no rotations (other than those for overcorrection) or spaces in the upper arch, and the buccal segments from the cuspids distally should have 14 degrees nonprogressive buccal root torque.


The arch form should be a modified catenary curve consisting of five separate radii –

one for the front of the arch form, one for each cuspid-bicuspid area

and one for each buccal segment from

the first bicuspid distally.

The widest point of the lower arch would be at the mesiobuccal cusp of the mandibular first molars and at the first bicuspids.

The widest point of the maxillary arch would be at the mesiobuccal cusps of the first molars.


Correction of crossbites.

Reduction of jaw relationship (orthopedic correction).

Elimination of crowding.

Establishment of space for severely malposed teeth

Consolidation of the lower arch.

Levelling of the curve of Spee.

Finishing of the lower arch.

Treatment Priorities


Overcorrection of buccal segments, curve of Spee,

rotations, and root positions at extraction sites

Establishment of the desired molar and buccal segment relationship.

Consolidation of maxillary space and retraction and/or intrusion of the maxillary anteriors.


Positioning and torque of maxillary anteriors, to allow them to occupy sufficient space to encase the lower arch and still maintain functional overbite.

Final detailing of tooth positions. (This should entail only minor, rapidly executed movements such as vertical height, minor rotation, and in-out).


It is of so importance that the lower arch must be finished and in the correct position to act as a template to receive the upper teeth, so that the upper teeth can be set to the lowers.


Each tooth must be considered individually, as the position of each tooth affects the positions of all the other teeth.

Regardless of the type of attachments, bracket placement is of more importance in achieving a good occlusal intercuspation.

Improperly placed brackets should be corrected at the earliest possible time during the course of treatment

Detailing of Tooth Positions in Treatment


Twelve-year molars are the teeth most commonly involved in occlusal interference .

It is therefore, important to see that these teeth are placed in proper positions.

So it is important to band all 2nd molars.


Normally tipped incisors occupy more space than those that are straight up and down

Torqued incisors describe the arc of a bigger circle than those that are not and cuspids that have their contact areas gingival to the adjacent contact points of the bicuspids and lateral incisors may take up less space in the arch than they ought to.


Rotations to the mesial cause upper molars to take up too much space in the arch and cause the buccal segments to fit more Class II.

Insufficient buccal root torque of upper molars makes for balancing and centric interferences.


One of the greatest problems in attempting to treat orthodontically to centric relation is that of avoiding extrusion of the posterior teeth and encouraging excess vertical alveolar growth, thus creating a molar fulcrum.

When the fulcrum has been created, one of two things occurs:

1. Appearance of an anterior open bite through the bicuspids and development of a tongue-thrust swallow.

2. No open bite, but clicking of the TMJ's and/or a tightness or stiffness of the mandibular musculature, usually associated with pain or discomfort of any combination of mandibular muscles.

Molar Fulcrum


The fulcrum effect can be observed on cephalometric laminagraphs showing the condyles being projected downward and distally towards the tympanic plates as the teeth are closed into habitual centric occlusion


ROTH’S PRESCRIPTION AND

TREATMENT MECHANICS


Roth Andrews


The use of straight wire appliance & the manner in which teeth are moved.

Andrews attempted to translate teeth throughout treatment without ever tipping teeth.

This leads to the necessity of utilizing sliding mechanics & a number of different series of brackets to solve the problem of translating teeth.

ROTH PHILOSOPHY


In the Roth approach, tipping of teeth is allowed but the attempt is to keep it minimum so that no complex mechanics requires to upright teeth.

Too many brackets in Andrews’ prescription

Translation – friction

Overcorrection

One prescription for all his patients

ROTH PHILOSOPHY


The Roth PrescriptionTooth II

molarI Molar II PM I PM Canine Lateral Central

Maxilla 0/-14(14o

offset)

0/-14 (14o

offset)

0/-7 0/-7 9/-2 9/8 5/12

Mand. 0/-304o offset

1/-304o offset

0/-22 0/-17 7/-11 0/0 0/0


Lower cuspid crowns angulated mesially 5 degrees, with the incisal tip lmm higher than the incisal edge of the lateral incisors.

{Note :The lower cuspids should have a slightly exaggerated mesial rotation on extraction cases.}

The lower bicuspids should be uprighted 1 degree from their normal mesial inclination and should have a slight distal rotation (more so on an extraction case). The contact point should be adjacent to the contact point on the lower cuspid distal surface.

Roth Prescription


The upper bicuspids should be uprighted to 0 degrees from their normal 2-degree mesial inclination, with no rotation, except for some distal rotation in an extraction case

The upper cuspid must have its contact points adjacent to the contact points of the upper bicuspid and lateral incisor, to establish proper length for cuspid guidance. It should have 11 to 13 degrees of mesial crown tip, and mesial rotation of 4 degrees, on an extraction case..

Roth Prescription


5o more torque in upper incisors.Less torque in upper canines.2o more tip in canines.2o anti-rotation in canines and PMs.Upright posterior segments.Over-correction of U molar offset and torque.

Roth Prescription


Lower posteriors –

3o distal tip.

Distal rotation.

Roth Prescription


Molar tubes with no upper molar offset

“Super torque” anterior brackets

Canines with 0o tip

Roth Prescription


In 1984 the "Attract" brackets were introduced


“Sapphire" Brackets


Bracket placement – as advocated by Andrews FACC except –

Upper anteriors and lower incisors bonded more incisally .

Lower canines bonded slightly more gingivally.

In addition, the maxillary central incisors should be bracketed at equal height to lateral incisors.

Roth Prescription


Archform – ‘Truarch’Flatter anteriorlySharp curve in Canine PM

regionGentle curve at posterior legs

Roth Prescription


Roth’s treatment mechanics


Ricketts VTO with the centric relation –adjusted head film tracing

Jarabak analysis

Selection of treatment mechanics

Repositioning of the mandible on the tracing


Depend upon type treatment mechanics.

0.022 slot is better –Wire size selectionControl of torque in buccal segmentIn terms of stabilizing arches as anchor units

&For orthognathic surgery.

0.018 Vs 0.022


1. Correction of Crossbites2. Correction of jaw relations3. Eliminate severe crowding4. Create space in the arch for severely

malposed/impaced teeth5. Alignment of teeth in the individual arches

Treatment Objectives


6. Begin space closure7. Finish the lower arch8. Achieve class I relationship of the buccal

segments9. Retract and intrude maxillary anterior teeth.10. finishing and detailing

Treatment Objectives


3 phases –

1. Unlocking phase

2. Working phase

3. Finishing phase

Treatment mechanics


Major correctionsCross bites Severely malposed teeth

Use of RME, Quadhelix, Bimetric arches & Utility arches. Jarabak helical loops in light wireBraided wires

Unlocking Phase


Unlocking Phase

Jarabak light wire helical loops


Main objective –

Gross corrections

Alignment with flexible wires – so that heavier wires can be used later.

Unlocking Phase


Closure of extraction siteCorrect a-p jaw relation & dental relationIntrusion, if required.

Space closure with Double keyhole loopIntroduced by John Parker. 19x26 mil rounded edge rectangular wire

Working phase


Double keyhole loop – Space closure with one wireMedium between tipping and translationPermit either anterior retraction or posterior

protraction.Control of canine rotationUsed as elastic hooks.

Working phase


Asher face bow for retracting anteriors en masse.

12 – 15 oz of force for upper anteriors.

Working phase


Working phase


Some tipping occurs after space closure – 18x25 blue Elgiloy heat treated with COS

0.018 steel special plus 16 x 22 yellow Elgiloy 2 ½ turn helix


0.018 steel special plus


18x25 blue Elgiloy heat treated with COS


16 x 22 yellow Elgiloy 2 ½ turn helix


After uprighting – 21 x 25 SS wire with only archform.Occasionally 22 x 28 SS wire.


High angle cases – Avoid heavy wires – max use of Nitinol and

TMA and braided wiresSpace closure on 0.016” SS wireUprighting with 19x25 TMA/Nitinol/braided

wire


Bimax cases – Initial space closure with 0.018” or 0.020” wire

with double keyhole loopsOnce teeth are upright – intrude with Utility

archContinue space closure with 19x26 double

keyhole loops and Asher face bow


Maximum retraction and torque control21 x 25 SS or Elgiloy double keyhole loopsMaximum torque controlReduce posterior ends


Place full sized wires and let brackets expressDrop to braided – settling elastics

Short Class IIs- minimum extrusion.


Case report – Bimax.


Pretreatment


Retraction


After Space Closure


Post Treatment


Factors that result in mesial migration of molars –

Heavy wires for leveling COS Attempts to gain rapid alignment with heavy

wires Uprighting distally tipped canines Lingual root torque of max. incisors Arch expansion with labial archwire Retracting extremely procumbent anterior

teeth

Anchorage considerations


Procumbent teeth offer a lot of anchorageOnce teeth are upright, they retract easily.

Space closure can be done on any wire, as long as it is done slowly.

Anchorage considerations


Thank you…

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