REVIEW ARTICLE
Year : 2013 | Volume
: 1 | Issue : 2 | Page : 110--113
Orthodontic considerations of extraction – A review
Mallikarjun Reddy1, Santosh Kumar Goje2, Zarana Purohit3, Kunal Patel3,
1 Reader, Dept. of Orthodontics, K.M. Shah Dental College and hospital, Sumandeep Vidyapeeth, Piparia - 391760, India
2 Professor & HOD, Dept. of Orthodontics, K.M. Shah Dental College and hospital, Sumandeep Vidyapeeth, Piparia - 391760, India
3 MDS Student, Dept. of Orthodontics, K.M. Shah Dental College and hospital, Sumandeep Vidyapeeth, Piparia - 391760, India
Correspondence Address:
Zarana Purohit
MDS Student, Dept. of Orthodontics, K.M. Shah Dental College and hospital, Sumandeep Vidyapeeth, Piparia - 391760
India
Abstract
Incorporation of soft tissue consideration, retention, changing trend in appliance design and treatment biomechanics has led to a lot of controversy in decision of extraction in orthodontics. Hence an attempt was made to review the orthodontic considerations for the choice of extraction in an orthodontic treatment. The literature was refined with the advanced search option for case reports, meta-analysis, and randomized control trial, retrospective and prospective studies. We observed that extraction of second premolar was more advantageous in orthodontic treatment.
How to cite this article:
Reddy M, Goje SK, Purohit Z, Patel K. Orthodontic considerations of extraction – A review.J Integr Health Sci 2013;1:110-113
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How to cite this URL:
Reddy M, Goje SK, Purohit Z, Patel K. Orthodontic considerations of extraction – A review. J Integr Health Sci [serial online] 2013 [cited 2023 Jun 9 ];1:110-113
Available from: https://www.jihs.in/text.asp?2013/1/2/110/239492 |
Full Text
Introduction
Extraction of premolars is the preference of treatment when the teeth are proclined/ protruded. The function of extractions in orthodontic treatment has been a contentious subject for over a century. Maxillary protrusion cases with a high mandibular plane angle have some clinical difficulties. In such cases, each cephalometric plane spreads out with large angles and masticatory muscles are weak. Maxillary protrusion cases with a high mandibular plane angle were re-estimated through a consideration of how natural anchorage is established by occlusal force.
It is fair to say that even today, controversy still exists in orthodontic treatment planning in terms of extraction or non extraction. Angle[1] thought that full complement of teeth could reside in the jaws, in an ideal occlusion with the first molars in a Class I occlusion. Extraction was abhorrence to his ideals, as he believed bone would adapt in their new position around the teeth, according to Wolff’s law.2 However, in 1911 Calvin Case strongly opposed non extraction philosophy of Angle suggesting that extractions were necessary to relieve crowding and for stability of treatment.[3]
During 1930-1970’s Charles Tweed retreated with extraction in those cases which showed relapse; which were formerly treated by non extraction philosophy & found occlusion to be much more stable.[4]
Tweed argued that premolar extractions were needed in order to compensate for the decrease in the interproximal teeth wear due to reduction in the intake of coarse diet.[5] Over the past 20 years, there has been a rise in the percentage of non extraction cases in the average orthodontic practice, which now stands as high as 80%.[1] According to Lama Hussam Jarrah, the clinical choice of extraction of teeth is highly debatable. Since literature suggested such a controversial observation, we attempted to review the literature in relation to orthodontic considerations of extraction.
The literature search was performed in two electronic databases. PubMed (January 1950 – January 2012) Ovid Embase +Ovid Embase Classic (January 1947 - January 2012). The following journals were additionally searched: American Journal of Orthodontics and Dentofacial Orthopedics (January1960 - January 2012), Angle Orthodontist (January1960 - January 2012), European Journal of Orthodontics (March 1970 - January 2012) and Journal of Orthodontics (April 1974 - January 2012). Grey literature was searched using Google Scholar. The literature was further refined with the advanced search option for case reports, meta analysis, randomized control trial, retrospective and prospective studies.
A total of 1231 articles were available when the literature was reviewed in relation to extraction in orthodontics. Of these 1231 article, 889 were case reports, 224 were retrospective studies, 79 were prospective studies, 31 were meta analysis and 8 were randomised control trial. These 1231 articles were filtered to 60 articles considering the inclusion criteria of evaluating the outcome of orthodontic extraction in terms of the effect of extraction site on anchorage, effect of extraction site on the amount of lip retraction, effect of extraction site on the amount of tooth size arch length discrepancy, effect of extraction site on the vertical facial dimension and clinical considerations. Articles which revealed serial extraction, congenitally missing teeth and extraction for surgical treatment were excluded.
Since the effect of teeth extraction in an orthodontic treatment had many outcomes, we reviewed the selected literature in the following aspects:
Importance of extraction site for anchorage consideration.Importance of extraction site on the amount of lip retraction.Importance of extraction site on the amount of tooth size arch length discrepancy.Impact of extraction site on the vertical facial dimension.Clinical considerations.
Anchorage:
A total of 15 articles were observed in relation to impact of extraction site over anchorage. It was observed that over the years, anchorage needs the choice of extraction. In high anchorage cases first premolars are extracted; while in borderline cases the choice of extraction would be second premolars. These choices were based on the foundation of William’s Hypothesis in1969; which stated that there would be a change in the relative root surface areas by a change in the location of the extraction site, between the anterior and posterior segments, which is necessary to influence the potential for incisor retractions.[6] Creekmore in 1997 enumerated this clinically; when first premolars in the lower arch are extracted, the posterior teeth move anteriorly about one-third of the space, parting two-thirds of the space for correction of crowding and for incisor retraction.{Table 1}
Lip Retraction:
A total of 12 articles were observed when literature was appraised in relation to impact of orthodontic extraction on soft tissue lips. There are anecdotally based expectations of the esthetic benefit of one premolar extraction sequence over another. In 1949, Nance advocated extraction of second premolars of both upper and lower to limit the amount of incisor retraction during space closure, in order to achieve better lip seal and fullness in the lateral lip profile.[7] Choice of one sequence over another was based on proposals which were largely derived from clinical observations with inadequate scientific evidence. [8] Proffit highlighted the differences in the amount of incisor retraction and mesial molar movement with different extraction patterns through clinical observation. [9] The depth of lip curvature was affected by the pretreatment thickness of the upper and lower 1 · lips[10].
Tooth Size arch length Discrepancy:
To manage the tooth-size-arch-length discrepancy, or arch crowding, the traditional method of choice was first or second premolar extractions. Extraction of maxillary second premolars is preferable to removal of first premolars for some adult cases. When we appraised the literature on the selection of extraction based on tooth size arch length discrepancy we observed a total of 14 articles. We observed that arch length tooth material discrepancy between the upper and lower dental arches may produce deviations from an ideal occlusion at the end of orthodontic treatment.
Maxillary lateral incisors, maxillary second premolars, and all four third molars are the most variable teeth in their crown size.[6]
In extraction cases, premolar size discrepancies can have an intense effect on the final occlusion.[11] Saatçi, Yukay in 1997, showed that the removal of the four 1st premolars created the more severe tooth-size discrepancy compared to the extraction of all four 2nd premolars. In his study, the mandibular second premolar showed the maximum mean mesiodistal dimension. This result is in accordance with the opinion expressed by Bolton in 1962, that the removal of lower 2nd premolars often creates the potential for a better occlusion compared to the removal of the 1s’ premolars.[12]
Facial Vertical Dimension:
We observe a total of 10 articles on impact of orthodontic extraction on facial and dental height. Earlier it was hypothesized that second premolar extraction permits the molar to move more forward than first premolar extraction consequently limiting the wedge effect. Mesial movement of the molars leads to counter-clock wise rotation of the mandible and a decrease in the vertical facial height. Therefore, in normal grower and horizontal grower patients, first premolar extractions are selected and vertical grower patients are treated with extraction of second premolars.
Clinical Considerations:
Extraction of premolar provides about 8 mm of space per quadrant and is the usual way to provide space in order to relieve crowding, retract incisors that are too protruded and to move the molars mesially. Bimaxillary protrusion in adolescent patients has conventionally been treated by extracting the four first premolars and retracting the anterior teeth.[16],[17]
In a molar distoclusion, extracting the premolar which matches mesiodistal width of the first molar mesiobuccal cusp will result in a more harmonious posterior Bolton relationship.[18],[19] If the first premolar which is wider is extracted, it becomes almost impossible to close the space distal to the canine completely because of this Bolton discrepancy. The clinical crown height of the first premolar is generally higher than that of the second premolar providing a more esthetic smile. Moreover, extraction of the first premolar results in an unpleasant gap that will not be closed for many months, which is especially bothersome to adults.[21]
After appraising a total of 9 articles we observed extraction of second premolars was more advantageous in comparison to first premolars.
Clinical advantages of extracting second premolars are:[13]
Easier bracket bonding to the first premolars.Highest incidence of bracket bond failure of second premolars.Extraction of first premolar leads to furrow formation.Easier to extract second premolars.Chances of fracture during extraction are less.
Extraction consideration in lingual orthodontics
Takemoto[22] suggested that the anchorage value of posterior teeth in the lingual technique is more compared to labial technique because of the less distance of the lingual brackets to the center of resistance of tooth. Additionally, the direction of forces during space closure creates a lingual crown torque and distal rotation of the molar crown, which is favorable for cortical bone anchorage. Kurz and Bennett[23] suggest that the decreased arch perimeter increases the rigidity of lingual arch wires, which may increase anchorage control while retraction mechanics. The larger slot size of the posterior lingual attachments gives maximum frictionless sliding retraction with no anchor loss. Extraction choices62’ 63 often differ in lingual Orthodontic in different patients.
Drawbacks of extractions:
Extraction has been a contentious topic for as long as the specialty of orthodontics has existed. Some authors consider that the extraction of premolars leads to vertical dimension collapse creating temporomandibular disorders.[14],[15] Concomitantly, over-retraction and retroclination of the incisors cause the facial profile to flatten, bring about premature anterior contacts, and distally displace the mandible and mandibular condyle.
Conclusion
Several factors control the preference of teeth for extraction to achieve an acceptable, aesthetic and functional occlusion. Literature also revealed a highly debatable comparison between the first and second premolar extraction. Convenient bracket bonding on first premolar, increased bracket bond failure of second premolars and furrow formation on first premolar lead to decline of first premolar as choice of extraction. Chances of fracture during extraction are less. Still premolar extractions are considered as a valuable adjunct for resolution of orthodontic problems. Since second premolars have a more incidence of congenital malformation, they should be the most favorable extraction choice followed by first premolars.
References
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