Extractions in orthodontics

it explain need for extraction, choice of teeth for extraction, Wilkinson extraction, extraction of permanent teeth without appliance therapy, balance extractions, compensating extractions, additional factor to consider in extraction of teeth.

1. Extractions in Orthodontics Dr. Shweta A. Kolhe BDS.MDS (Orthodontist). PhD Scholar.

2. The philosophy of extraction in conjunction with orthodontic treatment is not new. Extractions in orthodontics requires the reduction of one or more teeth include serial extraction- carried out as an interceptive procedure during the mixed dentition period. Therapeutic extraction- treatment procedure for gaining space.

3. Extraction and controversy in orthodontics Edward Angle- belied that an individual was capable of having 32 teeth in normal occlusion and orthodontic treatment for every patient involved expansion of arches. Calvin Case- argued that arches could always be expanded so that teeth could be placed in alignment, neither aesthetics nor stability would be satisfactory in the long term for many patients. thus advoated extraction of teeth.

4. Charles Tweed- observed that the post-treatment occlusion was more stable in patients treated with extraction of four first premolar. Begg - in Australia, argued that premolar extractions were required in order to compensate for the lack of interproximal wear seen in the modern dentition, through lack of a coarse diet. I t is advisable that each case must be assessed on its merits with more sensible approach based on the requirements of the individual case rather than the two extremes seen in the past century.

5. Need for extraction Arch length-tooth material discrepancy- The presence of tooth material in excess of the arch length can result in crowding of teeth or proclination of anteriors . In many cases the tooth material-arch length disproportion cannot be treated by increasing the arch length. Hence reduction of tooth material is the only alternative.

6. Sign of arch length discrepancy

7. Sign of arch length discrepancy

8. Correction of sagittal inter-arch relationship - Angle Class I : characterized by a normal sagittal inter-arch relation. Thus it is not advisable to discourage the development of one dental arch more than the other. Hence in Angle’s Class I cases, it is preferable to extract in both the arches.

9. Ange Class II: upper dental arch is forwardly placed or the lower arch placed back. Thus by extracting only in the upper arch it is possible to reduce the abnormal upper proclination and also to discourage the forward development of the upper arch. - where there is lower arch crowding or the molars are not in full Class II occlusion, may be necessary to extract in both arches.

10. Angle Class III: Beneficial to avoid extraction in the upper arch as it may affect the forward development of the maxilla. Angle class III cases are preferably treated by extraction only in the lower arch or by extraction in both arches.

11. Abnormal size and form of teeth: Anomalies includes macrodontia, severely hypoplastic teeth, dilaceration and abnormal crown morphology. Skeletal jaw malrelations : Sever skeletal malrelationship of the jaws ma not be satisfactorily treated using orthodontic appliances alone. Surgical respective procedures along with extraction maybe required.

12. The Choice of teeth for extraction The Choice of teeth for extraction depend on number factors including: Arch length tooth material discrepancy The direction and amount of jaw growth The facial profile The state and position of teeth in particular The entire dentition Age of patient

13. Extraction of upper incisors An unfavorably impacted upper incisor that cannot be brought to normal alignment. A buccally/ lingually blocked out lateral incisor with good contact between the central incisor and canine can be extracted. If one of the lateral incisors is congenitally missing, the opposite lateral may have to be extracted in order to maintain arch symmetry. A grossly carious incisor that cannot be restored may have to be sacrificed. Malformations of incisor crowns that cannot be restored by prosthesis may necessitate their extraction. Trauma or irreparable damage to incisors by fracture may indicate their removal. An incisor with dilacerated root cannot be efficiently moved by orthodontic therapy. It is hence preferable to extract them.

14. Extractions of Lower Incisors If one of the incisors is completely out of the arch with good inter-dental contact between the rest of the teeth. A lower incisor that was traumatized, or exhibiting severe caries, gingival recession or bone loss may have a poor prognosis. Presence of severe arch length deficiency is often characterized by the presence of fan-shaped flaring out of the lower incisor crowns. In these cases it may not be possible to flatten the lower anterior segment by extracting teeth further distally in the arch. Thus one of the incisors may have to be extracted so as to improve the crowding and axial inclination of rest of the incisors.

15. In mild Class III cases with lower incisor crowding, one of the lower incisors may be extracted to achieve normal overjet, overbite and to relieve crowding. Cases where a tooth size discrepancy exists, for example upper peg shaped laterals or missing upper lateral incisors, it may be extracted to achieve normal overjet, overbite and to relieve crowding. Cases where a tooth size discrepancy exists, for example upper peg shaped laterals or missing upper lateral incisors, it may be of benefit to extract a lower incisor. Treatment of Class I cases with moderate lower labial segment crowding of up to 5 mm (i.e. the size of a lower incisor) may be treatment with loss of a lower incisor.

16. Extraction of one lower can be considered in adult who have had previous loss of premolars in each quadrant and present with late lower labial segment crowding.

17. Extractions of Canine The canines develop far away from their final location. In addition they a long path of eruption from their site of development to their final position in the oral cavity. Thus the canines are highly susceptible to ectopic eruption and impaction. Such unfavorably impacted canines or canines that have erupted in unusual locations may have to be removed. A canine that is completely out of the arch with reasonably good contact between the lateral incisor and first premolar is an indication for its extraction.

18. Premature shedding of a deciduous canine usually indicates the extraction of its fellow on the opposite side of the arch to restore symmetry. In Class II cases if the lower deciduous canines are shed early, the upper deciduous canines should also removed so as to avoid worsening of the post- normalcy (Class II tendency). In Class III cases if the upper deciduous canines are shed early, it may necessitate the extraction of the lower deciduous canines to avoid worsening of the pre-normalcy (Class III tendency). Deciduous canines may be extracted as a part of serial extraction procedure.

19. Extractions of First Premolars Reasons for extraction : Their location in the arch is such that the space gained by their extraction can be utilized for correction both in the anterior as wel as the posterior region. The contact that results between the canine and second premolar is satisfactory. The extraction of the first premolar leaves behind a posterior segment that offers adequate anchorage for the retraction of the six anterior teeth.

20. Indications for first premolar extraction: The teeth of choice for extraction to relieve moderate to severe anterior crowding of the upper or lower arch. The first premolars are extracted for correction of moderate to severe anterior proclination as in a Class II, division 1 malocclusion or a Class I bidental protrusion.

21. Extraction of second premolars To relieve mild crowding and proclination where anchorage loss is desirable Unfavorably impacted In open bites, they are preferred over first premolars as deepening of bite is encouraged. If grossly decayed or has a large filling with questionable prognosis, then they are questionable prognosis, then they are extracted instead of first premolars.

22. Extractions of first permanent molars Reasons for avoiding extraction of first permanent molars: Does not give adequate space in the incisor region. Extraction of the first molar result in deepening of the bite. The second premolar and molar may tip into the extraction space. Mastication may be affected.

23. Indications for first molar extraction Minimal space requirement for correction of mid anterior crowding or mild proclination . Grossly decayed molar or heavily filled teeth. Molars that are extruded or with marked periodontal involvement. Open bite cases can benefit from extraction of first molar, as there is a tendency for the bite to deepen after extraction of first molars. Orthodontically retracted cases presenting with Angle Class II malocclusion where the first premolars have already been extracted.

24. Wilkinson extraction Wilkinson advocated extraction of all the four first permanent molars between the ages of 8 ½ - 9 ½ years. The basis for such extractions is the fact that the first permanent molars are highly susceptible to caries. Benefits of extracting the first molars at an early age are: Their extraction provides additional space for eruption of the third molars. Thus impaction of third molars can be avoided. Crowding of the arch is minimized.

25. Wilkinson’s extraction has number of drawbacks: The extraction of first molars offers limited space to relieve crowding. The second bicuspids and second molars rotate and may tip into the extraction space. The removal of the first molars deprives the orthodontist of adequate anchorage for any orthodontic appliance.

26. Extractions of second permanent molars To prevent third molar impaction To relieve impaction of second premolar Lower incisor crowding To enable distalization of first molars Open bite cases.

27. 1. To prevent third molar impaction Cases where third molars are upright or not tipped mesially more than 30 0. then upper second molar extraction if carried out prior to the eruption of the third molars, results in satisfactory third molar position. 2. To relieve impaction of second premolar Premature loss of ‘E’ allow drift of first permanent molar leaving inadequate space for second premolar such case extraction of second molar allow distal movement of first permanent molars and offer sufficient space for the second premolar to erupt.

28. 3. Lower incisor crowding very mid crowding in the anterior part of the arch can be relived by extraction of second molars. 4. To enable distalization of first molars Rapid and efficient distalization of first permanent molar can occur. 5. Open bite cases Extraction of second molars deepens the bite.

29. Extractions of third molars Etraction of third molar does not yield space that can be used for decrowding or reduction of proclination . Reasons are as follow: Grossly impacted Grossly malformed Eruption of third molars cause late lower anterior crowding.

30. Extractions of permanent teeth with-out appliance therapy Extraction of the lower first premolars are often associated with spontaneous decrowding of the lower anteriors . Such spontaneous decrowding by drifting of teeth, referred to as driftodontics are less frequent in the upper arch.

31. Balance extraction Removal of a tooth from one side of a dental arch result in tendency for the rest of the teeth to move towards the extraction space. Thus the midlines of the arch may shift to the side of the extraction space. To avoid such unaesthetic shifts of the dental arch, balancing extractions are advocated. Balancing extraction refers to removal of another tooth on the opposite side of the same arch.

32. Compensating Extractions Compensating extraction refers to extraction of teeth in opposite jaws. Compensating extractions are carried out to preserve the buccal occlusal relationship. In a class I relation it is usually advisable to extraction in both the arches to preserve the buccal occlusal relationship.

33. Additional factors to consider in extraction of teeth Quality of the teeth Hypoplastic, heavily restored or carious teeth should generally be removed in preference to healthy teeth. Abnormalities of tooth form Teeth of abnormal form or size may be considered for removal as they can look unsightly and be difficult to align. Medical history e.g. patient with cardiac problem may need antibiotic prophylaxis prior to extraction of teeth. Extraction is potentially traumatic experience.

34. Facial pattern and extractions Dolichocephalic facial pattern Dolichofacial patients feature increased facial height relative to the width, exhibiting a long and narrow face. They have hypotonic facial muscles in the vertical direction and can have anterior overbite. They suffer from greater anchorage loss, which helps in closing spaces. Greater control should be exercised, however, in order to avoid excessive anchorage loss and the consequent lack of space to ensure the planned correction. Extrusive mechanics should be avoided, as well as distal tooth movement.

35. Brachycephalic facial pattern : Brachyfacial patients facial width is greater than their facial height, displaying a broad, short an globular face. These patients are not as prone to anchorage los due to certain muscle characteristic (hypertonic masticatory muscles) that hinder tooth movement. Many patients have deepbite . Since in these cases tooth extractions tend to worsen the vertical overlap, adequate mechanical control is required.