INCISOR EXTRACTION
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Introduction The debate on extraction goes a long way back into the history of dentistry Historically, it is well known that Dr. Angle was against extraction. Angle declared his non-extraction mind by the statement. “The best balance, the best harmony, the best proportion of the mouth in its relations to other structures require that there shall be the full complement of teeth and that each tooth shall be made to occupy its normal position normal occlusion.� www.indiandentalacademy.com
The great extraction debate of the 1920’s between Dr. Case and Angle’s devotees were well known and documented in orthodontic annuals. Few dared to oppose angle and those who dared like Dr. Case had to pay a heavy price. It was Dr. Tweed, who publicly endorsed extraction after the death of Dr. Angle. In fact Dr. Tweed was so candid and generous that he re-treated many of his cases with extraction free of cost (during 1940’s The introduction of light wire deferential force technique in 1950’s by Begg-further enhanced the acceptance of extraction as a mode of orthodontic therapy
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The last quarter of the century saw the swing of the pendulum more towards non-extraction. Early treatment Acceptance of functional therapy. Growth modification by orthopedic methods. RME better anchorage control, changing esthetic for a fuller face and profile, face-lift concepts are some of them. Development of three dimensionally controlled brackets of PEA systems (Fully programmed). www.indiandentalacademy.com
Why should we extract teeth?
Primarily for gaining space Decrowding Retraction Leveling of curve of spee Correcting the sagittal interarch discrepancy etc. With the evolutionary trend of reduction in jaw size, space has become scarce.
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Orthodontist is essentially a “space manager” – creating, deploying and expanding the space in the arch has been our primary task.
Once the non-extraction options of gaining spaces (expansion, molar distalization, protraction of anteriors, proximal reduction, and derotation of posteriors) are rejected on the merits of the case, orthodontist sets himself to extract teeth. www.indiandentalacademy.com
Objectives TD Foster, W.R Proffit Extraction of teeth in orthodontic treatment will be necessary in 2 main circumstances. ď Ž For the relief of crowding. ď Ž For the correction of Anterior / Posterior dental arch relationship.
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Need for extraction Arch length – tooth material Discrepancy ď Ž 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 mercenary to reduce the dentition size by the extraction of teeth.
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Correction of sagittal inter arch relationship
Abnormal sagittal malrelationship such as class II / III malocclusion may require extraction to achieve a normal interarch relationship. In a class I- it is preferable to extract in both the arches In class II with abnormal upper proclination, normal alignment of the lower teeth and where point A is abnormally forward relative to the B point, it is advisable to extract teeth only in the upper arch and to retract the maxillary incisors and canines
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when the lower arch is crowded or molars are not in full cusp class II molar relationship, it might be preferable to extract in both the arches.
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Class III cases are usually treated by extracting teeth only in the lower arch.
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Different extraction procedures:
Balancing extraction. Compensating extraction. Phased extraction. Serial extraction. Enforced extraction Wilkinson extraction. Therapeutic extraction. Atypical extraction www.indiandentalacademy.com
Balancing extraction This is done to maintain the symmetry and midline of the arch
Compensating extraction. Removal of the equivalent tooth in the opposing arch to maintain buccal occlusion.
Enforced extraction Extraction carried out by compulsion www.indiandentalacademy.com
Wilkinson extraction Wilkinson advocated extraction of all the four first permanent molars between the age of 8½ and 9 years.
Serial extraction Orderly removal of selected deciduous teeth and permanent teeth in a predetermined sequence
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Therapeutic extractions . The choice of teeth for-extraction depends upon.
Arch length discrepancy The antero-posterior positioning of teeth in relation to the facial line Presence of orthognathic or prognathic profile.
Age and dental development. The degree of alvelo-dental prognathism. Direction of jaw growth / especially lack of jaw length. Degree and site of crowding. www.indiandentalacademy.com
Contemporary extraction guidelines (proffit)
Discrepancy <4mm extraction rarely indicated Discrepancy 5-9 mm Non-extraction / extraction treatment depends on the hard tissue / soft tissue characteristics and on how the final position of the incisors will be controlled. Discrepancy 10mm or more Extraction almost always required to obtain enough space. www.indiandentalacademy.com
Incisor extraction Maxillary incisors Indications Unfavorably impacted maxillary incisors Buccally or lingnally placed lateral incisor with good contact between central incisor and canines. If a lateral incisor is crowded in linguo-version with its apex palatally displaced and if the canine is erupting in a forward position and distally is inclined, lateral incisor extraction is indicated. Grossly carious incisor that cannot be restored. Trauma / irreparable damage to incisors by fracture www.indiandentalacademy.com
Mandibular incisors
Indications When one incisor is completely excluded from the arch and there are satisfactory approximate contacts between other incisors.
Severely malpositioned incisor.
Poor prognosis as in case of trauma, caries,
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bone loss etc
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Lower canines are severely inclined distally and lower incisors are fanned – it is very difficult to correct the condition by extractions further back in the arch. The most upright incisor is selected for extraction so that other teeth can be tipped into correct position.
In mild class III incisor relation with an acceptable upper arch and lower incisor crowding, a lower incisor may be extracted to achieve normal overjet, overbite and to relieve crowding
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contraindications
It is often very tempting to extract a lower incisor to relieve crowding particularly which it is confined to the anterior segment but its extraction should be avoided as far a possible because it causes. Remaining anterior teeth to imbricate Although crowding may be relieved in the short term forward movement of buccal teeth leaves incisor contacts and positions less than ideal. Deep bite. www.indiandentalacademy.com
Lower inter canine width (ICW) decreases resulting in a secondary reduction in the upper inter canine width with crowding in the upper labial segment. Retroclination of lower incisors. It is not possible to fit upper four incisors around three lower incisors, either on increase in over jet (or) upper incisor crowding have to be accepted. www.indiandentalacademy.com
Clinical considerations
Mandibular incisors are the objects of very significant therapeutic value in clinical orthodontist and their relevance as follows. They from the first sign of an incipient malocclusion. They are difficult to treat as they relapse readily. Crowding of the mandibular incisors in the most frequent anomaly www.indiandentalacademy.com
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Wayne A. Bolton analysis (1958)
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Bolton pointed out that the extraction of one tooth or several teeth should be done according to the ratio of tooth material between the maxillary and mandibular arch, to get ideal interdigitation, overjet, overbite and alignment of teeth.
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Procedure for doing Bolton analysis
Overall ratio =
Sum of mandibular 12 x100 Sum of maxillary 12
Average = 91.3% If overall ratio is greater than 91.3, then mandibular tooth material is excessive. Sum of mand =
Sum of max12 x 91.3 100
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If overall ratio is lesser than 91.3% then maxillary material is excessive.
Sum of max =
Anterior ratio =
Sum of man12x100 91.3
Sum of man 6 x 100 Sum of max. Average â&#x20AC;&#x201C; 77.2% www.indiandentalacademy.com
If anterior ratio is greater than 77.2% then the mandibular anterior tooth material is excessive.
Sum of man =
6 − sum of max . 6 x 77.2 100
•If anterior ratio is less than 77.2, then maxillary anterior tooth material is excessive. Sum of max. =
6 − sum of man. 6 x 100 77.2
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Review of literature ď Ž
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As a matter of fact lower incisor extraction to treat mandibular incisor crowding is not a new idea. Jackson in 1904 had illustrated a case where one incisor had been earlier removed and he chose to remove a second incisor because the remaining three were crowded and the intercanine distance was too narrow for their alignment. Owing to the close occlusion it was not considered practicable to increase the distance between the canines to correct the crowding www.indiandentalacademy.com
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Fisher: Demonstrated several cases in 1940 with a two incisor extraction plan and no retention. Schwarz: Reviewed 20-year post retention records of one patient who had congenitally missing two mandibular incisors. He was surprised to observe good long-term stability www.indiandentalacademy.com
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Riedel: Extreme crowding or protrusion of incisors often accompanied by loss of gingival line and bone overlying the labial surfaces of incisor roots, would be good indicators for mandibular incisor extraction. Riedel further wrote that extraction of two mandibular incisors may satisfy the requirements of maintaining arch form without expansion of inter canine width of the arch with nonextraction or with premolar extraction therapy, the inguinal inter canine width usually requires to be increased in order to gain adequate alignment and arch form. www.indiandentalacademy.com
Salzmann, reviewing Edward H. Angle’s philosophy of extraction in orthodontics, noted that angle regarded the extraction of an incisor, when the tooth was sound, to be inexcusable. Angle warned that extracting one incisor, as advocated by some, would lead to a less acceptable harmony between the occlusal planes of the remaining teeth in addition to an abnormal incisor overbite.
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Lower incisor extraction in orthodontic treatment “Vincent kokich and Peter Shapiro (angle orthodontist 1984)” They have presented four different cases –I their treatment plan, which included the extraction of one mandibular incisor and reduction of maxillary tooth width.
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Key consideration Tooth size analysis is an important part of the evaluation because in some situations this may indicate little likelihood of a successful result with an incisor extraction as in a case of significantly maxillary anterior excess. If the analysis, shows lower anterior excess the incisor extraction might have a positive effect. Kokich and Shapiro have mentioned that the indication are relatively low, however the possibility of lower incisor extraction should be a part of every orthodontist portfolio of treatment techniques. www.indiandentalacademy.com
Mandibular incisor extraction – post retention evaluation of stability and relapse. Reidel R.A 1992 (AJO-DO) Little R.M Their purpose was to access the stability of mandibular dental alignment in patients treated. With conventional edge-wise mechanism following the extraction of one (or) two mandibular incisors. The results were favorable when compared with premolar extraction case. Single incisor extraction - 29% Two-incisor extraction - 56% Pre molar extraction - 70% www.indiandentalacademy.com
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When two mandibular incisors are removed, the mandibular teeth are re-arranged so that the mandibular canines become mandibular laterals and if central incisors are extracted the laterals become centrals 1st premolars assume the place of canines.
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Single lower incisor extractions Albert owen (JCO 1993) Class I molar relationship, indicating that the final buccal interdigitation will be acceptable. Moderately crowded lower incisors Severe – premolar extractions Mild –without extraction Mild or no crowding in the upper arch Acceptable soft tissue profile Minimal to moderate overbite / overjet Minimal growth potential.
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Lower incisor extraction is orthodontic treatment Ali-Akber Babreman AJO-DO-1977. Extraction of single mandibular incisor can be employed as a compromise treatment of certain malocclusions, if the end result fulfills the requirements for healthier dentition, which is functionally and esthetically harmonized in relation to the surrounding structures. Best-suited cases for this procedure are those Crowding which have the following specifications www.indiandentalacademy.com
Good normal maxillary dentition Perfect buccal interdigitation Severe lower anterior crowding with lack of space for almost one lower incisor. Lower anterior arch length discrepancy is greater than 4 to 5 mm. Anterior tooth ratio is more than 83mm.
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Contraindications Deep-bite case with horizontal growth pattern Bimaxillary crowding cases, which have no tooth size discrepancy in the incisor area. All cases having incisor discrepancy due to either small lower incisor / large upper incisors. In conditions exhibiting a deep overbite pattern, reduction of the mandibular anterior unit should be avoided. He concluded his study by stating that this procedure should be considered as a last resort measure since it involves the most important stabilizing area of occlusion. www.indiandentalacademy.com
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