“Extractions In Orthodontics”

Introduction

Painless removal of teeth from its socket is termed as Extraction. It is one of the most common methods of gaining space in the arch.

In orthodontics, there are two major reasons to extract teeth:

To provide space to align the remaining

teeth in the presence of severe crowding.

To allow teeth to be moved so that protrusion can be reduced or so skeletal class II or class III problems can be camouflaged.

The alternative to extraction in treating dental crowding is to expand the arches.

The alternative for skeletal problems is to correct the jaw relationship, by modifying growth or surgery.

Need For Extraction

Arch length – tooth material discrepancy :- Ideally the arch length and tooth material should be in harmony with each other. If the dentition is too large to fit in the dental arch without irregularity, it may be necessary to reduce the dentition size by the extraction of teeth. It is not normally acceptable to increase the dental arch size, because the increased dental arch dimension would not be tolerated by the oral musculature.

Arch length - tooth material discrepancy - may result in spacing or crowding.

Crowding - May be due to arch length deficiency. Tooth material excess - Necessitates

extraction.

Less than 4mm arch length discrepancy extraction rarely indicated.

5-9 mm arch length discrepancy - non extraction or extraction, depends on the details of both the hard- and soft-tissue characteristics of the patient and on how the final position of the incisors will be controlled.

10 mm or more: extraction almost always required.

Correction of Sagittal Inter arch Relationship : In a Class I malocclusion it is preferable to extract in both the arches because it is not advisable to discourage the development of only one arch more than the other.In most Class II cases with abnormal upper proclination, it is advisable to extract teeth only in the upper arch and to retract the maxillary incisors and canines. In case of the lower arch crowding it is advisable to extract in both the arches.

Class III cases are usually treated by extracting teeth only in the lower arch to discourage the forward growth of mandible.

Extraction for the Relief of Crowding :-

Extraction for the relief of crowding will be governed by:

The condition of the teeth

The position of the crowding

The position of the teeth

condition of the teeth:

Fractured, hypoplastic, grossly carious teeth & teeth with large restorations would be more favorable for extraction than sound, healthy teeth.

The main consideration is the long term prognosis for the tooth & the secondary consideration is the appearance of the tooth.

Abnormal size and form of teeth- may necessitate their extraction in order to achieve satisfactory results. Eg: macrodontia, severe hypoplasia , dilaceration and abnormal crown form.

position of the crowding:

If crowding is located in one part of the dental arch, it will be more readily corrected if extractions are carried out in that part of the arch.

However, crowding of incisors is usually relieved by extraction of premolars, thus giving a more pleasing final appearance and occlusal balance.

First premolar, positioned in the center of each quadrant is usually near the area of crowding.

position of the teeth:

Teeth which are grossly malpositioned and would be difficult to align, are often the teeth of choice for extraction.

The position of the apex of the tooth must be considered, as it is usually more difficult to move the apex than to move the crown.

DIFFERENT EXTRACTION PROCEDURES Balancing extractions Compensating extractions Phased extractions Enforced extractions Wilkinson extractions Serial extractions Driftodontics. Therapeutic extraction.

Balancing Extractions:

Removal of a tooth on the opposite side of the same arch (although not necessarily the antimere) in order to preserve symmetry. Designed to eliminate centre line displacements that will require fixed appliances for their later correction. Balancing extractions are not necessary if the dental arch is spaced.

Compensating Extractions:

Removal of the equivalent tooth in the opposing arch to maintain buccal occlusion. In a class I occlusion with crowding in some cases, extraction is the only treatment needed. Here, the arches being equal sizes, it would be necessary to extract in both arches to maintain lateral symmetry ie., a tooth would need to be removed from four quadrants of the jaws. Compensating extractions preserve inter arch relationship by allowing the posterior teeth to drift forward together.

Wilkinson extractions:

Wilkinson has advocated the extraction of the 4 first permanent molars between the ages of 8 ½ and 9 ½ years in selected cases on account of their susceptibility to caries.

He believed that this provided additional space for third molars and the resulting relief from over crowding.

Favors the preservation from caries of the remaining teeth.

Drawbacks of Wilkinson Method:

1. Excessive drifting of lower second premolars.2. Second premolars and second molars rotate

frequently as they erupt following extraction.3. Deprives operator of adequate anchorage for

orthodontic appliances.4. second molars erupt with mesial tilting to

contact second premolars resulting in inter dental space

Phased Extractions It may be possible to effect a change

in molar occlusion by extracting in one arch only, or a few months earlier than in the other. Thus extractions done in phases, so called as Phased Extractions.

Enforced Extractions :-These extractions are carried out

because they are necessary as in the case of grossly decayed teeth, poor periodontal status, fractured tooth, impacted tooth, etc.

Driftodontics:This concept is applicable when extraction of the permanent teeth are done without appliance therapy. Teeth have a natural tendency to drift into the extraction space.Extraction of the lower first premolars are often associated with spontaneous de-crowding of lower anteriors. Such spontaneous de-crowding by drifting of teeth is referred to as Driftodontics, & is less frequent in upper arch.

Therapeutic Extractions: Extractions carried out for the purpose of treatment.

serial extraction: An interceptive orthodontic procedure usually

initiated in the early mixed dentition when one can recognize and anticipate potential irregularities in the dentofacial complex.

It is designed to avoid the development of a fully matured malocclusion in the permanent dentition in severely crowded mouths.

Planned extraction of certain deciduous teeth and later specific permanent teeth in an orderly sequence and predetermined pattern to guide the erupting permanent teeth into a more favorable position.

Various indications: 1) Class I malocclusion showing harmony and

balance between skeletal and muscular systems. 2) Arch length deficiency compared to tooth

material as indicated by one of the following cardinal clues:-

Absence of physiologic spacing. Midline shift of mandibular incisors due to

displaced lateral Incisor. Uni/ bilateral premature loss of deciduous canines

with midline shift. Abnormal or asymmetric primary canine root

resorption. Markedly crowded or irregular upper or lower

anteriors.

Lingual eruption of lateral incisors. Mesial eruption of canine over lateral incisors. Ectopic eruption. Flaring of lower anteriors Abnormal eruption direction and eruption sequence. Localized gingival recession of lower incisors.

contraindications: Class II/Class III malocclusions with skeletal

abnormalities. Anodontia/oligodontia. Class I malocclusion where lack of space is

slight and teeth are only slightly crowded. Midline diastema. Open bite Deep bite. When fixed appliance cannot be used to avoid

arch collapse.

technique of serial extraction:

1. NANCE METHOD:

Sequence of Extraction: (D4C) 1. Deciduous first molars. 2. First Premolar. 3. Deciduous canine.

dewel's method:(CD4) 3 Stages

1. Early extraction of deciduous canines to provide space for the incisors to assume correct alignment at the expense of the space for permanent canines.

2. Extraction of the first deciduous molars to permit early eruption of 1st premolars, especially in mandibular arch where normal sequence is for deciduous canines i.e., between 9 & 10 years.

3. Extraction of the first premolars to allow space for the permanent canines to erupt in the spaces formerly occupied by first premolars.

tweed's method (D4C) When the patient is between the ages of 7 ½ - 8½

years. Serial extraction is performed as follows:-

a) Extract all 4 deciduous 1st molars at the age of 8 years. If mandibular permanent incisors are not blocked out or severely crowded, Tweed advised maintaining the deciduous canines in position so that eruption of permanent canine will not be hastened.

b) When the I premolar teeth erupt to about the level of the crest of the alveolar mucosa they are extracted.

c) The deciduous canines are also extracted at this time.

ADVANTAGES

Treatment is more physiologic as it involves guidance of teeth into normal positions using physiologic forces.

It eliminates/ reduces the duration of multi banded fixed treatment.

Lesser retention period at completion of treatment.

More stable results; tooth material and arch length are in harmony.

DISADVANTAGES Requires clinical judgment. No single approach

can be universally applied.

Treatment time is prolonged; spread out over 2-3 years.

Patient co-operation is vital.

As extraction spaces close gradually, patient has a tendency to develop tongue thrust.

CHOICE OF TEETH FOR EXTRACTION

Choice of teeth to be extracted depends on local conditions which include:

Direction and amount of jaw growth. Discrepancy between size of dental arches and

basal arches. State of soundness, position and eruption of

teeth. Facial profile. Degree of dentoalveolar prognathism. Age of patient. State of dentition as a whole.

INCISORS Maxillary incisors:

The incisors are rarely extracted as a part of orthodontic therapy, especially the maxillary central incisors

Indications –▪ Unfavorably impacted maxillary incisors that

cannot be brought into normal alignment within the arch.▪ If one of the lateral incisor is congenitally

missing, opposite lateral incisor may be extracted to maintain arch symmetry.▪ Grossly carious incisor that cannot be

restored.▪ Fracture or irreparable damage to incisors by

fracture▪ Incisor with dilacerated root

Mandibular incisors It is often very tempting to extract a lower

incisor to relieve crowding particularly when its confined to the anterior segment but its extraction should be avoided as far as possible because it causes:-

a. Remaining anterior teeth tend to imbricate.

b. Although crowding may be relieved in the short term, forward movement of buccal teeth leaves incisor contacts and positions less than ideal.

However, in a few well defined cases, extraction of lower incisors may be appropriate-

a. When one incisors is completely excluded from the arch and there are satisfactory approximal contacts between other incisors.

b. Poor prognosis for mandibular incisors trauma, caries, bone loss, gingival recession.

c. Lower incisor is severely malpositoned.

CANINES:

The permanent canines are important teeth and are not frequently extracted as part of orthodontic treatment.

Extraction of canines can cause:-

Flattening of face Altered facial balance Change in facial expression.

Some of the conditions under which the canines may have to be extracted are:

1. Canines highly susceptible to ectopic eruption or impaction

2. Canine that is completely out of the arch with reasonably good contact between lateral incisor and first premolar

3. premature shedding of a deciduous canine usually indicates extraction of its fellow on opposite side of the arch

4. Deciduous canines may be extracted as apart of serial extraction procedure.

FIRST PREMOLARS: It is the tooth most commonly extracted as part

of orthodontic therapy especially for the relief of crowding because:-

1. It is positioned near the centre of each quadrant of the dental arch and since is near the site of crowding i.e space gained by their extraction can be utilized for correction both in anterior and posterior region.

2. First premolars extraction is least likely to upset molar occlusion and is the best alternative for maintaining vertical dimension.

3. The contact that results between canine and the second premolar is satisfactory

4. First premolar extraction leaves behind a posterior segment that offers adequate anchorage for retraction of the 6 anterior teeth.

SECOND PREMOLARS

indications for extraction:

1. When second premolar is excluded completely from the arch due to forward drift of first permanent molars after early loss of deciduous second molars.

2. In mild anterior crowding cases, second premolar extraction is preferred over first premolar as space closure and vertical control is easier after anterior alignment.

FIRST MOLAR

The first permanent molar has been esteemed as untouchable from the very beginning of the history of orthodontics; it is considered as the consistence of the dentition always at its right position in the arch.

Extraction of first molars is avoided because-

It does not give adequate space in the incisor region. Deepening of bite. Poor contact relation between second premolar and

second molar. Second premolar and second molar may tip into

extraction space. Mastication is affected.

SECOND MOLARS

Lower second molar is often not removed for the relief of crowding. Its position at the end of the dental arch means that it is usually removed from the site of crowding and is not itself actually malpositioned through crowding.

But extraction may be indicated in the following cases:-

To relieve impaction of second premolars- To relieve impaction of mandibular third molars- When permanent second molars are impacted

THIRD MOLARS Extraction of third molars during orthodontic

treatment does not yield space that can be used for de crowding or reduction of proclination.

Indication for III molar extractions:- Grossly impacted third molars that are unable

to erupt into ideal position: The erupting mandibular third molars have

been implicated to be the cause of late lower anterior crowding, although the evidence is not clear cut

Malformed third molars which interfere with normal occlusion should be extracted.

Indications For Extraction Of Different Teeth

A

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