rotation of teeth & its management

ROTATION OF TEETH & ITS

MANAGEMENT

PRESENTED BY DR : MANAS . AJIT MOKASHI

•Rotations are tooth movements that occur around their long axis.

Types of tooth movement :• Pure translation : It is of three types 1, Intrusion ,

2, Extrusion, 3,Bodily movement.• Pure rotation : It is of two types 1,Transverse

rotation eg : tipping & torqueing. 2, Long-axis rotation eg :rotation of tooth around its long axis.• Generalized rotation :Any movement that is not

pure translation or pure rotation is generalized rotation, it is seen routinely in day to day practice.

TYPES OF ROTATION

• THERE ARE TWO TYPES OF ROTATION :• 1, Mesio-lingual or disto-buccal.• 2, Disto-lingual or mesio-buccal.

POSSIBLE ETIOLOGY OF ROTATION OF TEETH ARE :

• 1, Severe crowding ,• 2, Supernumerary tooth , or odontomas .• 3, Typical class II div II malocclusion , where upper central

is lingualy inclined , leaving insufficient room in dental arch. 4,Unilatral cleft where usually teeth lateral to cleft is rotated.

• 5, Over retained deciduous teeth .• 6, Unereupted teeth at the base of root of the completely erupted teeth.• 7, Ectopic canine.• 8,Scar tissue from trauma.• 9, Hereditary factors.• 10, Spacing.• 11,Different types of forces acting on the teeth such as masticatory forces, forces from tongue, digit sucking habit , lip biting etc.

Tongue thrusting

Lip biting .

Advantages of derotation :• Rotated posterior teeth occupy more space than normally placed teeth. Derotation of these teeth provide some amount of arch length.• Absence of rotation is one of the keys of normal occlusion •Non rotated teeth have tight contact with its adjacent teeth.•Derotation is essential for proper maxilla to mandible relation & proper inter cuspation .•Derotation is essential for equal distribution of occlusal forces.

Treatment of rotations.

• In fortunate few cases as we resolve the etiologic factors causing rotation , the severity of the rotation reduces.• But others require extensive treatment , &

have tendency to relapse .

Force required for derotation is 35-60 gms , & 50-100 gms , depending from case to case.

• In edgewise treatment derotation is performed by placing first order bends like IN-OUT bends.

Derotation using NITI wire :

The derotation of premolars and canines with a NiTi wire is a simple and clear method that can also derotate extremely rotated teeth without interrupting the levelling phase. The occurring torquing moments are quite moderate, and the forces from the eccentric bend can be intercepted by the existing levelling arch. Since the nickel-titanium wire has a large range of activation, reactivation during rotation is not necessary. The tooth to be derotated is fixed to the levelling arch in order to avoid a palatal or lingual movement of the tooth. The element for derotation must have a cross section of .018” x .018”, so that the vertical slot is completely filled

Space management :

• Treatment of anterior tooth rotation requires space. • There should some provision for space

gaining in treatment planning.

Use of removable appliances :• Mild rotation can be treated using

removable appliances.• Removable appliances which has “Z”

springs {double cantilever springs} & labial bow.

USE OF FIXED APPLIANCES :• It is the most appropriate mode of treatment when

there are multiple rotated teeth present.• Teeth derotation can be done by using rotational

wedges. They can be wedged in between teeth and arch wire.

• Mild rotation can be effectively treated using NITI. Arch wires.

• Their super elasticity allows easy engagement of wire into the bracket slot.

• This brings derotation , alignment , and levelling of the teeth to a certain extent.

• Elastics threads , elastic chain or power chain , elastic bands, springs can be used to derotate the teeth around its long axis by engaging them with lingual buttons.

• In a couple system of derotation elastics are attached on lingual side and wrapped around the tooth in the direction of derotation. • A force couple system is also useful in treating

rotation . Here elastics are used both bucally as well as lingually .

Rotating springs: it is engaged through vertical slot, it brings derotation along teeth's own axis.

Molar rotation and expansionLemons and Holmes reported that a majority of patients with Class II malocclusions exhibit maxillary first molars that are rotated mesially around the palatal root. In other words, the palatal root may be in a normal, Class I position despite giving the clinical appearance of Class II when the first molar is viewed from the buccal surface. The implication is that, in some cases, simply producing a distal rotation of the molar will produce a Class I molar relationship for many patients.Molar distalizing appliances that produce forces on the lingual surfaces of the upper molars may produce additional inappropriate mesial rotation.

RETENTION :

• DEROTATED TEETH ARE DIFFICULT TO RETAIN IN THEIR NEW POSITION.• They have very high risk of relapse because of

over stretched supra alveolar & trans septal fibre's.

• Long term stability can be achieved by PERICISION OR CIRCUMFERENTIAL SUPRACRESTAL FIBROTOMY where gingival fibres are incised to prevent relapse.

Retention appliance which may be used are :

Thank you.