Progressive slenderizing technique

PROGRESSIVE SLENDERIZING TECHNIQUE

Presenter : Zia Ul Islam

Definition

Mechanical reduction of the dental interproximal enamel layer, which is carried out in order to re-shape the contact area and decrease the mesiodistal diameter of the teeth to facilitate alignment.

The objectives of slenderizing include:

• Correction of dentoalveolar discrepancies

• Treatment of tooth size discrepancy (Bolton discrepancy)

• Adjustment of interdental contact point to the papilla shape

• Increasing the interdental contact surface in order to contribute to better stability of corrected rotations

• Correction of asymmetries in order to improve

aesthetics.

Indications

1. CrowdingSlenderizing is a technique for the treatment of minor crowding, but anexperienced orthodontist also can treat moderate crowding cases.2. Bolton discrepanciesThe upper and lower canine-to-canine and upper and lower molar-to-molar Bolton indices indicate where slenderizing might be undertaken to improve the occlusion.

The relation between the lower molar-to-molar tooth size is 91.3 ± 1.91

The canine-to-canine relation is 77.2 ± 1.65

If a ‘12’ Bolton index is achieved, a molar Class I relationship is obtained

and

if the ‘6’ Bolton index is achieved, a canine Class I relationship is obtained.

3. Triangular and ‘barrel’ tooth shapes

According to Bennett and McLaughlin

three main tooth shapes:

rectangular

triangular

and a barrel-shaped teeth

Tooth shape has great importance in orthodontic treatment.

The rectangular shape allows a wide and stable contact point without visible interdental spaces.

The triangular shape allows a reduced and very occlusal or incisal contact point with BLACK GINGIVAL TRIANGLES.

Barrel shaped teeth have a reduced contact point in the middle with apparent embrasures at the incisallevel.

If the crown has a triangular shape, the distance between the bone crest and the contact point is relatively large. In these cases, the interproximal papilla tends to be absent.

4. Macrodontia

Dental shape does not have any influence on the enamel thickness but it is aesthetically more advisable to perform slenderizing on macrodontic rather than on microdontic teeth.

5. Over-extended crowns and fillings

In such cases, slenderizing is indicated to obtain normal tooth shape and dimensions

6. Bilateral dental asymmetries Slenderizing, veneers or crowns are often

indicated in order to compensate for dental asymmetries, upper anterior region.

7. Adult patient (narrowed pulp chambers) Adults have narrower pulp chambers, so

slenderizing can be carried out with less risk of compromising dental sensibility than in young patients.

8. Low caries index Slenderizing should only be carried out in

patients with a low caries index, in order to avoid increase in susceptibility.

9. Multiple rotations, in order to achieve better stability In patients who present with multiple

rotations, slenderizing can result in wider interproximal contact areas, which makes the tooth position more stable with respect to the risk of relapse

Contraindications

• Patients who do not consent to slenderizing..

• High caries index

• Poor oral hygiene: high bacterial plaque index

• Rectangular-shaped teeth

• Young patient (large pulpal chambers)

• Enamel hypoplasia, dentine hypoplasia, etc.

• Interproximally abraded teeth

Advantages of slenderizing

--Minimizing the need for extractions and their consequences

The consequences of extraction orthodontic therapy are:• Difficulties in extraction space closure due to loss of archwire control• Difficulties in root paralleling next to extraction sites• Possibility of the space re-opening (relapse), especially in adult patients.

--Less loss of tooth materialSlenderizing causes less tooth volume loss than extractions.--Smaller tooth movementsWith the progressive slenderizing technique, tooth movements required are smaller than in extraction cases.--Less root resorption riskWith smaller tooth movements and shorter treatment times, the risk of root resorption is reduced.

-- Better aestheticsBy using the ‘artistic grinding’ slenderizing, black gingival triangles are avoided, positioning the contact point at 5 mm from the bone crest; tooth asymmetries can be compensatand at the same time tooth shape can be improved.

• In the anterior group, incisors and canines, asymmetries should be compensated and midlines should be centred

• In premolars and molars, the cusps should remain untouched for intercuspation

• Slenderizing should be carried out in such a way that the interproximal contact point remains at the distance of 4.5–5 mm from the tip of the alveolar crest to assure black gingival triangles will not be visible due to the presence of the dental papilla.

How much enamel can be stripped?

The enamel layer at the level of the contact points has a minimum 1 mm thickness, except the lower incisors, where it is 0.6 mm. This allows the orthodontist to grind half layer: 0.5 mm on mesial or distal surface of all teeth, except of the the lower incisors where 0.3 mm can be removed.

Instrumentation for slenderizing The following instruments may be used:

Stainless steel strips

Burs

Discs

Intensive system for slenderizing

Dentacare system

Measuring instruments and gauges

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