Intrusion and extrusion Invisalign

Presentation Title

Intrusion and extrusion with Invisalign

M.Sanoudos DDS,PhD

Force distribution & Type of tooth movementOptimal forceThe amount of force and the area of distribution The force distribution varies with the type of tooth movement

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Force distribution & Type of tooth movementStrainStrain is defined as percentage of change in length of the material in relation to original length. When a force is applied to any material, such as bone, it undergoes deformation.

Strain = (change in length/original length) x100

The amount of deformation in the material relative to its original length, is the strain.

Forces should be kept low- high concentration of forces

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Force distribution & Type of tooth movementIntrusion-very light forces-concentrated in a small area Extrusion-Only areas of tension

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Optimum forces for various tooth movements-Proffit

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6Force DurationSustained force- cyclic nucleotides appear- only after 4 hoursLonger & constant the force- faster the tooth movement

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Type force duration-force decayContinuous forceLight- frontal resorptionHeavy- undermining resorption- constant-further U.ResorptionDestructive to the PDL & toothForce decayLight force-FR- no movement till activationHeavyUR- force drops-repair & regeneration occurs

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Mechanical Signaling

Is true intrusion a reality?

Am J Orthod Dentofacial Orthop 2006;130:709-14

Is true intrusion a reality?


Is true intrusion a reality?CONCLUSIONS Limited evidence is available about the quantity ofattainable molar intrusion. True molar intrusion appears to be achievable in the maxillary arch, but theamount of evidence is minimal. The clinical significance of the magnitude of the trueintrusion reported for high-pull headgear is questionable as the sole treatment option to correct open bitesin clinical situations.


How good is Invisalign in moving teeth?


How good is Invisalign in moving teeth? Part2 Am J Orthod Dentofacial Orthop 2009;135:27-35




How good is Invisalign in moving teeth? CONCLUSIONS

1. The mean accuracy of tooth movement with Invisalign was 41%. The most accurate tooth movement was lingual constriction (47.1%). The least accurate tooth movement was extrusion (29.6%).2. Maxillary and mandibular canines achieved approximately one third of the predicted rotation. At rotational movements greater than 15, the accuracy for the maxillary canines was significantly reduced.

3. With the exception of canine rotation, no tooth was significantly less accurate in movement.


How good is Invisalign in moving teeth? 4. Lingual crown tip was significantly more accuratethan labial crown tip, particularly for the maxilaryincisors.

5. The severity of pretreatment overjet might influencethe accuracy of anterior tooth movement with Invisalign.

6. There was no statistical difference in accuracy between maxillary and mandibular teeth of the sametype for any tooth movement studied.


How good is Invisalign in moving teeth? Part2

Angle Orthodontist, Vol 85, No 5, 2015





How good is Invisalign in moving teeth? Part2 Most of the studies presented with methodological problems: small sample size, bias and confounding variables, lack of method error analysis, blinding in measurements, and deficient or missing statistical methods. The quality level of the studies was notsufficient to draw any evidence-based conclusions

CAT is an effective procedure that is able to alignand level the arches in non-growing subjects.

The anterior intrusion movement achievable withCAT is comparable to that reported for the straightwire technique.

CAT is not effective in controlling anterior extrusionmovement. Contrasting results have been reportedin relation to the posterior vertical control, and adefinite conclusion cannot be drawn.

How good is Invisalign in moving teeth? Part2 CAT is not effective in controlling rotations, especially of rounded teeth.

CAT is effective in controlling upper molar bodilymovement when a distalization of 1.5 mm has beenprescribed.

CAT is not based on aligners alone. It requires theuse of auxiliaries (attachments, interarch elastics,IPR, altered aligner geometries) to improve thepredictability of orthodontic movement.


Case 1 (From Invisalign Global Gallery)Treatment InformationAge:20Gender:MInvisalign Treatment Option:FullDiagnostic Summary:Class I relationshipAnterior open biteCrowdingUse of:IntrusionExtrusionIPRTADsinserted buccally between 1.6 (UR6) and 1.7 (UR7), and between 2.6 (UL6) and 2.7 (UL7), and lingually between 1.5 (UR5) and 1.6 (UR6), and between 2.5 (UL5) and 2.6 (UL6) for 20 monthsElasticsOptimized ExtrusionOptimized Rotation

Case 1 (From Invisalign Global Gallery)


Case 1 Ceph data (From Invisalign Global Gallery)ANB 2.3SNA 81.4SNB 79.1 degWits -1 mm x/Md differential 47 mmLAFH 91.3 mm MP-SN 35.5 degIMPA 86.4 degUI-SN 105.5 deg



Case 1 (From Invisalign Global Gallery)Treatment SummaryResults Achieved:Maintained initial Class I occlusionNormaloverjet and overbite achievedAll treatment goals were achievedTotal treatment time:24 monthsNumber of Aligners:Maxillary: 42+27=69Mandibular: 42+27=69Comments:Orthognathic surgery avoidedRetention:Maxillary: ViveraretainerMandibular: Viveraretainer

Case 2Treatment InformationAge:60Gender:FInvisalign Treatment Option:FullChief Concern:Open bite and affected speechDiagnostic Summary:All permanent dentition presentHistory of severe bruxismHistory of TMJ with severe pain (~2 years prior to orthodontic evaluation)

Treatment Plan and ClinCheck Analysis:TADs to intrude maxillary posterior 1st, 2nd, and 3rd molarsExtrude upper 2-2 by 1mmDistalize upper left quadrant with precision cutButton for class II elastics on the left side to correct class II occlusionPatient strongly advised but declined all 3rd molars extraction Maxillary 3rd molars finally extracted after completion of Invisalign treatmentUse of:DistalizationExtrusionIntrusion

Case 2

Case 2

Case 2

Case 2

Case 2

Case 2Treatment SummaryResults Achieved:Anterior and posterior crossbites closedDental midlines correctedClass II malocclusion on left side correctedUnable to extrude upper anterior teeth since patient declined to allow attachment placement on upper 2-2; results were obtained by intruding posterior dentition onlyMandible auto-rotatedOverjet and overbite correctedPatient extracted U8's after completion of treatment; open-bite closed despite presence throughout treatment11 TADs placed due to patient's uncooperation with foods and likely unfavorable bone quality

Case 2Total Treatment time:17monthsNumber of Aligners:Maxillary: 51Mandibular: 51Comments:4 TADs used to help intrude maxillary 1st, 2nd, and 3rd molarsClass II elastics used to correct class II on the left sideRetention:Maxillary: Other clearMandibular: Other clear

Discussion

Intrusion and extrusion Invisalign

Healthcare

Intrusion and extrusion Invisalign