Extraction in orthodontics /certified fixed orthodontic courses by Indian dental academy


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Extraction in orthodontics /certified fixed orthodontic courses by Indian dental academy

  1. 1. Extractions in orthodontic treatment www.indiandentalacademy.com
  2. 2. INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  3. 3. Introduction: Extraction is necessary part of the treatment in some cases, but in others it is contraindicated. Before extractions are considered, an exhaustive study of the case must be made by a clinical examination of the patient, paying particular attention to caries or restored or traumatized teeth which might subsequently give rise to symptoms. Radiographs should be scrutinize to ensure the presence of all teeth . www.indiandentalacademy.com
  4. 4. If a clinicain desires to change the facial profile, the choice of teeth prescribed for extraction will influence the result significantly. In simple terms, if maximum anterior retraction in both the upper and lower arches is the objective, most orthodontists would remove the four first premolars. For lesser retraction in the lower face ( patients with a large chin button), the upper first and lower second premolars would be removed. Less overall retraction occurs with the extraction of the four-second premolars, and the least occurs with removal of the fours first molars. www.indiandentalacademy.com
  5. 5. DIAGNOSIS AND TREATMENT PLANING. In 1965, Henry gave two basic criteria for extraction of second bicuspids: 1. Mild degree of corwding and an excellent profile. 2. No crowding and fullness of the lips. www.indiandentalacademy.com
  6. 6. Although Begg stated that second premolars should not be extracted instead of frst premolars unless they are carious or poorly formed, there is no reason why Henry’s criteria could not be applied to the Begg technique. Nance was one of the first to draw attention to the option of extracting second premolars in mild discrepancy cases (the sort of case in which we wish we might extract a part of a tooth rather than a whole tooth). He stated that this avoided a disned-in-face and that there was less tendency for residual spacing. Carey advised second premolar extractions in cases with a discrepancy greater than 5mm. Dewel observed that in the borderline case, extraction creates more space than is necessary and this must be closed by reducing the anchorage value of the buccal segments. Logan noted similar findings and listed other factors of significance when second premolars were extracted. www.indiandentalacademy.com
  7. 7. 1. The maxillary first premolar is more esthetic than the second. 2. The contact point of mandibular first molar and first premolar tended to stay closed. 3. Rapid space closure reduces the possibility of buccal or lingual bone furrows in the extraction site. 4. Overbite can be controlled easily. 5. .Closure of anterior open bite is facilitated by reducing posterior vertical dimension. www.indiandentalacademy.com
  8. 8. DeCastro considers the mammalian dentition as an arrangement of three independent segments-an anterior segment ending at canine and two posterior segment. When the second premolar is extracted in the middle posterior segment, only this segment is shortened. But, when first premolar are extracted, both the segments are shortened. Hence there will be greater effect on the functional integrity of the dentition. www.indiandentalacademy.com
  9. 9. History The role of extraction in orthodontics was recognized by John Hunter (in 171) in his natural history of teeth. Spooner (in 1839) advised the extraction of four premolars or the 1st molars when defective. Farrar (in 1888) considered judicious extraction an essential requisite “for the prevention and correction of irregularities”. He recognized that indiscriminate extraction may “.......... Create a new difficulty while removing the original one”. Pierce, writing in the Dental Cosmos of October, 1959, advocated extraction in tooth crowding as a means for simplifying orthodontic procedure. www.indiandentalacademy.com
  10. 10. E.H. Angle on Extraction There have always been those who practiced extraction, even advocating it as a panacea for all types of malocclusion and for the reduction of dental decay in the remaining teeth. Extraction to avoid “collapse” and to improve facial appearance was advocated by Angle in his book. Angle States : It is difficult to lay down any precise rule regarding extraction, but it is a matter which involves the broadest consideration and closest study of each case, after taxing the judgement as much as any problem in orthodontia. He gives two reasons for extractions in Class I Malocclusion. www.indiandentalacademy.com
  11. 11. First, where the jaws are so small, either naturally or because of arrested development, that the angles of inclination would be too great if all the teeth were placed in line. Procumbency of incisor teeth. Second, where extraction is necessary form the requirements of the facial lines, for the development of the arches may be such as to afford on abundance of room for the malposed teeth, and yet placing them in the line of occlusion may result in marked dental or labial prominence and the facial result be more unpleasing than if the teeth had been allowed to remain in malposition. He states further..........There seems to be a difference of opinion as to the choice of teeth in case a sacrifice be necessary, either the first or second bicuspids are dental collapse. The orthodontist cannot always make the extraction decision on a priority basis. It is not always possible to predict what the profile will look if the teeth were not extracted.www.indiandentalacademy.com
  12. 12. Margolis, popularized the view that the most effective extraction strategy to relieve crowding is to extract the premolar teeth closest to the is the of crowding and this would dictate extracting first premolar in most cases. PROCUMBENCY OF MANDIBULAR INCISORS AS A CRITERION FOR EXTRACTION. When the ramus of the mandible is short, as indicated by a line drawn tangent to the mandibular plane passing through the occipital bone, instead of tangent to almost tangent to the bone, as pointed out by Atkinson, the mandibular incisors may appear to be in precumbent relationship but frequently will be found to be at 90° or less to the mandibular plane. www.indiandentalacademy.com
  13. 13. When the incisor teeth in different mandible are viewed in cross section, a variety of relationship can be seen between the body of the mandible and the teeth. In some mandibles, the entire dental arch may be situated lingual to the body of the mandible, when teeth showing an outward flaring to varying degrees. The mesiodistal relationship of the dental arch to the base of the mandible is an important factor in determining the need for extraction when facial esthetics are concerned. However, extraction of teeth does not depend solely on the degrees of procumbency of the mandibular incisors teeth in relation to the mandibular plane. The size of the gonial angle, the labial lingual position of the mandibular arch, the presence of tooth crowding and the relationship of the incisor teeth to the pogonion are most important factors in determining the need for extraction as a method of reducing facial prognathism than is incisor www.indiandentalacademy.com procumbency.
  14. 14. EFFECT OF EXTRACTION ON OVERJET AND OVERBITE This depends on the type of occlusion present and the tendency of overbite and over jet shown by the patient, the type of appliance used and the manner in which it is used. Extraction is not responsible per se for increase or decrease in overbite. When the anterior or posterior teeth are crowded with or without procumbency of the mandibular incisor and the basal arch shows the presence of the “Simian Shelf” (there is an extreme subalveolar constriction), extraction is indicated one jaw more than in the other. Extractions which have to be performed in Class I cases other than teeth completely displaced from the arch are usually better to be symmetrical, i.e., the same tooth usually being removed from each quadrant of the mouth, in both upper and lower arches. www.indiandentalacademy.com
  15. 15. Angle Class II. In some of these cases the upper dental arch may appear relatively further forward than the lower arch. Where such a condition has been diagnosed it may be desirable to discourage forward development of the upper arch more than the lower. Of the malocclusion in severe and the root apices of the lower teeth are in correct relationship to one another, extraction of a premolar tooth from either side of the upper arch will cause a relative impairment of the forward development of the upper arch and allow the upper anterior teeth to be moved palatally with appliances thus improving the upper and lower incisor relationships. The upper first premolars are usually the teeth of choice though some orthodontist favour the removal of the second premolars. In Class II treated by this method the posterior teeth retain their apparent post normal relationship which in functionally satisfactory and the method is often suitable for patients who are not likely to respond to extensive appliance therapy. www.indiandentalacademy.com
  16. 16. Extraction from the lower arch in Class II case are necessitated by extreme caries. It is almost always essential to extract teeth from the upper arch least the overject increase. Normally extractions one avoided in the lower arch unless indicated by the orthodontic treatment plan, in any particular case or for bringing the lower molar forward. On that case the second premolars are preferred. Angle Class III - Similar principles guide the decision to extract teeth from prenormal cases. When the treatment of Class III cases is complete, the upper incisor may be inclined labially to an abnormal extent and may be only be prevented from assuming a lingual relationship to the lower incisors by the degree of overbite. Because of the effect upon the forward development of the upper dental arch extraction of the upper teeth should be avoided in most cases. If such extractions are inevitable, consideration should be given to the reduction in numbers of the lower teeth. www.indiandentalacademy.com .
  17. 17. This is especially so where “the malocculusion is accompanied by the excessive forward development of the mandible”. For this reason, if extractions from the lower arch are considered necessary they should performed as early as possible in order that the maximum interference with the forward development of the dental arch is obtained. ADVERSE POSITION OF ROOT APICES Provided sufficient space exists the inclination of the crown of the tooth to an abnormal position is usually readily corrected with simple forms of orthodontic render extraction necessary for even where the tooth has not been displaced traumatically, its eruption likely to be impaired by the root deformity. www.indiandentalacademy.com
  18. 18. PRESERVATION OF SYMMETRY There is always a continuos normal forward movement of the teeth to maintain approximal contact. It is explained that the pressure caused by growth and eruption is guided round he arch by the lips to the midline where the forces from each side are equal and opposite and therefore balance one another. If the tooth is extracted form one side of the dental arch only, the forward movement of the teeth mesial to the space is impaired and therefore, pressure form that side is deficient. The pressure from the other side is normal however, the inequality of pressure may cause the incisors to be inclined towards the side from which the tooth was removed especially where the tooth was lost at an early age. www.indiandentalacademy.com
  19. 19. Where teeth are congenitally missing from one arch, the other arch being intact (the arch relation being normal and the muscular forces of the tongue, lips and cheek adequate) it may be advisable to balance it by symmetrical extraction of similar teeth from the opposite side. Similarly, where pathological conditions necessitate the extraction of the tooth from an arch, further extraction may be justified to preserve symmetry or to maintain the relative proportion in arch size. www.indiandentalacademy.com
  20. 20. EXTREME ABNORMALITY OF JAW RELATIONSHIP In those cases where treatment for a malocclusion has not been sought until a late age of fifteen years and above extraction of one or more teeth may well reduce the duration of treatment and overcome a possible lack of cooperation of the patient to a long course of treatment. It is particularly useful in children who have very little growth left. www.indiandentalacademy.com
  21. 21. LATE TREATMENT In those cases where treatment for a malocclusion has not been sought until a late age of fifteen years and above extraction of one or more teeth may well reduce the duration of treatment and overcome a possible lack of cooperation of the patient to a long course of treatment. It is particularly useful in children who have very little growth left. www.indiandentalacademy.com
  22. 22. CRITERIA FOR EXTRACTION The criteria for extraction may be summarized as follows: 1. When the labio-lingual dental relationship to the facial plane (N-Pg) where the dental arch is not crowded and is situated far enough in a lingual direction so that existing procumbency of incisor teeth does not produce facial proganthism while gonial angle is less than 125° and the ramus of the mandible is long enough for the base of the mandible to approach a parallelism with FH plane, extraction becomes a purely www.indiandentalacademy.com subjective procedure.
  23. 23. 2. The size of the gonial angle. The incisor procumbency in relation to the Frankfurt plane is more pronounced in the presence of a short ramus and an extremely obtuse gonial angle. 3. The axial inclination of the mandibular incisors and their effect on the Frankfurt mandibular incisor angle. 4. The type and degree of irregularity and crowding present in the dental arches. 5. The direction of jaw growth. 6. The relative difference in the size of the basal arches i.e. Basal arch length. 7. The thickness and distribution of the soft tissue covering www.indiandentalacademy.com the facial bone.
  24. 24. If the arrangement of the teeth is asymmetrical and the removal of only one premolar from an arch will permit the remaining teeth to be brought into good alignment, this may be done. When the posterior segment of the maxillary arch are narrower than the mandibular dental arch, extraction should not be undertaken until buccal lingual arch relation of the posterior teeth is established. After this is accomplished the necessity for extraction should be reevaluated. TWEED-THE FRANKFURT MANDIBULAR INCISOR ANGLE The Frankfurt mandibular planes are extended into space and meet to form the Frankfurt mandibular angle. The third angle is drawn along the long axis of the most labial mandibular incisor. The angles forming this triangle are used in diagnosis, classification, treatment planning and prognosis. www.indiandentalacademy.com
  25. 25. Tweed presents the role of the Frankfurt mandibular angle in determining the need for extraction as follows: When the Frankfurt mandibular plane angle range is 20° to 30°, the prognosis for favorable orthodontic is excellent for those nearest the 20° to good for those near the 30° extreme. Reduction of the alveolodental proganthism will require extraction of teeth where necessary to permit tooth alignment over the basal arches. Tweed found that about 60% of the malocclusions fall within the 20° to 30° range of the Frankfurt mandibular plane angle when measurement are taken from profile radiograph and more than half these cases require extraction of teeth. www.indiandentalacademy.com
  26. 26. When the Frankfurt mandibular plane angle is 30° to 35° as measured the prognosis for reducing the alveolodental prognathism varies form good at 30° to fair at 35°. When the Frankfurt mandibular plane angle range is 35° to 40°, the prognosis of reducing alveolodental prognathism is fair at 35° and unfavorable at 40°. When the Frankfurt mandibular plane angle range is 40° upwards, Tweed considers prognosis to be unfavorable. In some causes the removal of teeth in the 40° or above Frankfurt mandibular plane angle cases detracts from rather than enhances facial profile. www.indiandentalacademy.com
  27. 27. How considers tooth crowding to be due to deficiency in arch width rather than length. He found a relationship to exist between the total width of the mesiodistal diameters of the teeth anterior to the 2nd molars and the width of the dental arch in the 1st premolar region. Arch length is measured at the midline from the distal in measured at the midline from the distal marginal line of the 1st molar to the most anterior point of the basal arch as defined by Salzmam. This is then compared with the arch width for possible extraction. Cases with between 37 to 44% of the intercanine fossa width to mesiodistal arach width (1st molar to 1st molar) are in the doubtful category and extraction of the 1st premolars is the result of more or less subjective treatment planning. When the ratio between intercanine fossa width and the 1st molar to 1st molar width is less than 37%, it is considered by Howe to be indication of basal arch deficiency and extractionwww.indiandentalacademy.com is indicated. of the 1st premolar
  28. 28. SERIAL EXTRACTION Serial extraction is the planned and sequential removal of the primary and permanent teeth to intercept and reduce dental crowding problems. The principle of extraction of specific primary and permanent teeth was suggested as a means to eliminate arch length deficiency over 200 years ago, when Bunon proposed an extraction sequence that would improve arch length deficiency problems. The sequence consisted of ; 1. Extraction of the primary canines to permit the self-alignment of permanent incisor. 2. Extraction of the primary first molars to promote the eruption of the first premolar. www.indiandentalacademy.com
  29. 29. 3. Extraction of the first premolar to relieve the crowding and permit eruption of the permanent canines. Rationale : The rationale for serial extraction has its foundation of several basic biologic facts and processes; 1. Tooth material arch length deficiency 2. Physiologic tooth movement. 3. Normal dental, skeletal and profile development. Dental crowding the result of inadequate arch size, insufficient basal bone and /or excessive tooth material - is epidemiological the common types of malocclusion. www.indiandentalacademy.com
  30. 30. Physiologic tooth movement or drifting occurs in a rather predictable pattern dependent primarily on the dental age at the time of extraction. If the primary teeth are extracted prematurely, this will influence the eruption rate and position of permanent successors. The treatment objective for a serial extraction is to reduce or eliminate the need for extensive appliance therapy. Although this is an idealistic goal, it is the initial objective in considering serial extraction. www.indiandentalacademy.com
  31. 31. The signs or symptoms indicating that an arch length deficiency exists and that a serial extraction. Midline shift of the mandibular incisor due to a displaced lateral incisor. Premature moss of primary canine, abnormal or symmetrical primary canine root resorption. Ectopic eruption of maxillary first molar Labial but unerupted permanent canines that are extremely prominent, gingival recession on a labially displaced incisors, extreme labial displacement of a mandibular incisor, maxillo mandibular alveolar dental protrusion, unusual shape, size or number of teeth and crowded maxillary or mandibular teeth that are excessively inclined labially. www.indiandentalacademy.com
  32. 32. The indication for doing a serial extraction must correspond to the patients need and biologic characteristic and must fulfill the desired objectives. There is no absolute sequence for all situation. However, to select an ideal patient for a serial extraction, for an 8 year old with normal number, size and shape of teeth, a class I canine and molar relation with minimal overjet and overbite mayne chosen with symmetric arch length tooth size deficiency in the early stage of the middle mixed dentition, a normal eruption sequence and dental development present radiographically, a normal skeletal growth pattern, and a normal AP vertical and transverse skeletal pattern. www.indiandentalacademy.com
  33. 33. Treatment planning and extraction sequencing: Deciding on the timing and sequencing for extraction of primary and permanent teeth is the key to success. Unfortunately, there is no plan applicable to all situations. Every serial extraction must be individualised to accomplish the objectives for the particular patients developing malocclusion. Class I malocclusion - premature loss of primary canine. This situation is rather common and will usually be accompanied by a midline shift to the side from which the tooth has been lost. www.indiandentalacademy.com
  34. 34. If the skeletal, profile and dental patterns, the overjet, axial inclinations and the number, size shape and development pattern are normal and f there is 5 to 10 mm of arch length discrepancy per arch, the remaining primary canine should be extracted of the permanent first premolar have more than half the roots formed, the primary first premolars should extracted; if not primary first molar should extracted when the root formation is half completed. The first premolar should be extracted as they emerge. www.indiandentalacademy.com
  35. 35. Congenitally missing teeth Congenitally missing teeth excluding 3rd molars are observed in more than 5% of the population. The teeth most frequently missing are the mandibular 2nd premolars, maxillary lateral incisors and maxillary 2nd premolars when a congenitally missing tooth is observed in the middle mixed dentition period, one should make a decision as to whether to undertake a serial extraction. Interview of the fact that dental drifting can close apices, the plan should be formulated. Maxillary lateral incisor Lingually locked in lateral incisor are a definite indication of tooth size- arch length discrepancy. Delaying extraction may cause other cross bite or root resorption. www.indiandentalacademy.com
  36. 36. If the objective is to close the space, the desirable characteristic would be: 1. A crowded mandibular arch no spacing or crowding in the maxillary arch and a Class I buccal interdigitation. OR 2. No spacing or crowding in both aches and a Class II buccal interdigitation. www.indiandentalacademy.com
  37. 37. In the former the maxillary primary lateral incisors and canines and mandibular primary first molars and canines should be extracted when the canine roots have half formed. The mandibular first premolars are extracted when they emerge. It might be necessary to extract the maxillary primary 2nd molars to facilitate imterdigitation. Then the maxillary primary canines and lateral incisors are extracted when the maxillary canine roots are half formed. Again the extraction of either the maxillary or mandibular second premolar may be necessary to facilitate buccal interdigitation. www.indiandentalacademy.com
  38. 38. In patients with Class II tendencies or excess maxillary space, this procedure is not successful and one should consider prosthetically replacing missing maxillary laterals. Mandibular 2nd premolar In a patient missing a mandibular second premolar in whom there is maxillary crowding and a Class I buccal interdigitation one can consider the same sequence as a Class I malocclusion with the 2nd premolar and primary molar removal. This will be more successful if the extraction are done in the middle mixed dentition. www.indiandentalacademy.com
  39. 39. Choice of teeth for extraction The choice of the teeth to be extracted depends on the local conditions which include the direction and amount of jaw growth, discrepancy between size of the dental arches and the basal arches; sate of mobility, position and eruption of the teeth, facial profile, the degree of alveolodental prognathism, age of the patient and the state of the dentition as a whole. In adults the teeth to be extracted other condition being favorable are those that entail the least amount of tooth movement for obtaining favorable results. www.indiandentalacademy.com
  40. 40. Incisors They should not be extracted unless damaged beyond satisfactory repair. Extraction of incisor teeth should be avoided especially when the canine teeth are in infraversion or superversion since this tends to produce greater disharmony. When lateral incisors are severely fractured in young children, it becomes necessary to extract the broken incisor and move the adjacent canine to occupy the space. In the mandible, the space left by an extracted incisor should not be allowed to close by itself, because tooth shifting is not predictable. Active closure of the space is required by means of orthodontic appliances. Extraction of mandibular incisor teeth can lead to disturbance of the entire occlusion. Malocclusion treated in this manner shows a tendency to develop abnormal overbite and cusp-to-cusp occlusion of the buccal series of teeth. www.indiandentalacademy.com
  41. 41. When there is a decided discrepany in the size of the maxillary and mandibular incisors themselves, then consideration may be given to the removal of an incisor tooth through such cases are rare. The inter canine distance of the maxillary and mandibular teeth should be considered when contemplating extraction of incisor teeth. Occlusion with incisor tooth extraction show a tendency to cusp to cusp relation on one side of the dental arches with what is known as "silppage'. There may be a tendency to increased maxillary overjet and occasionally also a deep overbite. www.indiandentalacademy.com
  42. 42. Canines They should not be extracted by choice as an orthodontic measure because of their importance in maintaining facial expressions and balance. In order to avoid prolonged treatment with appliance or where it is impossible to bring the canine into normal alignment, it may be necessary to remove a canine when impacted or in ectopic eruption. First Premolar They are the teeth usually extracted when it is necessary to obtai stable results in malocclusion with dental arch and basal discrepancies . The choice depends on the age of the patient, the presence and severity of caries, presence of extensive filling in the dental arch. www.indiandentalacademy.com
  43. 43. When forward positioning of the molars is not required to any extent the 1st premolar should take precedence over the 2nd premolar as the teeth to be extracted. Second Premolar They may be extracted instead of the 1st premolar if they are not sound or their position in the arch is such that extended orthodontic tooth movement would be in the maxilla, however, the second and the third molars before emergence have their crowns inclined distally and bucally. www.indiandentalacademy.com
  44. 44. After extraction of a maxillary first molar, the adjacent eruption second permanent molar performs tipping movement in which the crown moves more mesially. This movement corresponds more or less with the normal changes in mesio-distal angulation that an erupting second permanent molar would experience if the first one had not been extracted at an early age. The tipping movement is however, a little greater. A considerably more unfavorable situation exists in that respect in the mandible. Under normal circumstances a second permanent molar that originally was mesially inclined would upright itself on eruption. Extracting the first permanent molar affects the eruption path of the not yet emerged second molar, which subsequently will display little or no up righting movement or even will tip more mesially. This last movement is the opposite to what is required to achieve an acceptable angulation after emergence. www.indiandentalacademy.com
  45. 45. In contrast to the mandibular teeth, the maxillary 2nd molar in the absence of the first molar show only a slight abnormality in the mesiodistal angulation. TO reach a good mesiodistal angulation the root apices of the maxillary molars do not need to move so far mesially as those in the mandible. It also makes a difference how far the eruption of the 2nd molar has progressed a the time the 1st molars are extracted. The mesio-lingual rotation of the second molar after extraction of the first molar is more pronounced in the maxilla than the mandible. Maxillary second molar rotate about an axis more or less through the mesiopalatal cusp and the palatal root. Madibular second molar also rotate mesiolingually but less so. www.indiandentalacademy.com
  46. 46. After extracting the first molar, the adjacent second molars drift more mesially in the maxilla than in the mandible. The mesial tipping of the second permanent molars (especially in the mandible) their mesial drifting and rotation (especially in the maxilla) and the distal tipping and rotation of the premolar(especially in the mandible) leads to a ramshackle occlusion. Both transversely and sagitally, good interdigitation is lacking. www.indiandentalacademy.com
  47. 47. Asymmetrical extraction: When in both jaws the first permanent molars are extracted on one side only, the changes will be limited chiefly to that side. The midlines will become displaced towards the extraction side. This deviation is limited in extent and is seldom recognized as an esthetic disorder. Of course the dental arch midlines often cease to correspond because the mandibular incisor migrate more than maxillary incisor. Pronounced asymmetries and disturbed occlusions develop when one side a mandibulat molar is extracted and a maxillary molar on the other side. www.indiandentalacademy.com
  48. 48. Definite contraindications prevail against extracting first permanent molars. Indications to extract one or more first molar for orthodontic reasons alone are seldom , if ever, encountered. If extraction therapy is required, preference for removal goes to premolars or occasional second permanent molars. Only when first molars are so defective that there can be no hope of keeping them intact despite the best care, and the premolars are sound, would the molars be sacrificed rather than the premolar or should be realized that such cases will require orthodontic therapy that is considerably more complex than usual. This certainly is undesirable in a situation where defective first molars are a symptom of a generally weak dentition with a high caries susceptibility. www.indiandentalacademy.com
  49. 49. The only actual indication for extracting first permanent molar is the impossibility of conserving them for a greater part of life. Sechwarz stated that when first permanent molars appeared likely to be lost as a result of caries before the age of 30 years, removal at an early age is indicated. In conclusion, a purely orthodontic indication is rarely found for extracting first molar. Nonetheless, these teeth are sometimes extracted in the context of orthodontic therapy. www.indiandentalacademy.com
  50. 50. Two circumstances justify this approach. The first is when removed of qualitative worthless first molar takes the place of extracting for example a sound premolar. The second is when orthodontic treatment required for other reasons can be employed to correct most of the undesirable effects for extracting defective first molars. In these cases extraction would not be contemplated as a part of orthodontic treatment if the molars were at all reasonable in quality. Second molar extraction: In the last few years, the extraction of the 2nd molar has become a matter of great interest and controversy within the dental profession. Liddle believes that many malocclusion develop because of eruption forces of the permanent second molars and that premolars is treating the effects rather than the cause of the malocclusion www.indiandentalacademy.com
  51. 51. CHRONOLOGY AND DIMENSIONS OF SECOND MOLARS Calcification of both the mandibular and maxillary second molars at 2 1/2 to 13 years of age 7 to 8 years the crown are fully formed. Eruption of the mandibular second molar is seen at 11 to 13 years; the root development is not completed until 14 to 15 years. The maxillary second molar erupts at 12 to 13 years of age with its final root formation realized at 14 to 16 years Average crown dimension for the mandibular second molars are 10.5mmm both mesiodistally and labio lingually. Crown height averages 70mm and tooth length 20.9mm. The maxillary second molar has an average mesiodistal diameter of 9mm and buccolingual dimension of 11m. mean crown height is 7mm with the averagewww.indiandentalacademy.com 18mm. tooth length being
  52. 52. Advantages and indications of second molar extraction According to Wilson and Graber - the following reasons were proposed as the major advantages and favorable results of second molar extraction. - Facilitation of treatment using removable appliance. - Reduction in the amount and duration of appliance therapy. - Disimpaction of third molars. - Faster eruption of third molars. - Prevention of dished - in appearance of the face at the end of facial growth. www.indiandentalacademy.com
  53. 53. - Prevention of late incisor imbrication. - Facilitation of first molar distal movement. - Distal movement of the dentition only as needed to correct the overjet. - Fewer residual spaces at the end of the orthodontic treatment. - Less likelihood of relapse. - Good functional occlusion. - Good mandibular arch form. - www.indiandentalacademy.com Reduction in incisal overjet.
  54. 54. Chipman believes that the procedure is indicated when; 1. The second molars are severely carious ectopically erupted or severely rotated. 2. Mild to moderate arch length deficiencies exist with good facial profile. 3. There is crowding in the tuberosity area with a need to facilitate first molar distal movement. According to Wilson premolar extraction in Class I crowded cases without the use of fixed appliance therapy will result in the tipping of teeth poor contact points, increase in overbite, and functional interference. On the other hand according to Wilson, extraction of the second molar extraction www.indiandentalacademy.com
  55. 55. Timing for mandibular second molar extraction. Kokich in his summary of presentation given by Scholz Stressed three criteria is to be met when making the decision on timing of the dentition. The third molar crowns should be completely formed but extraction should be performed before the root begins to develop. The axial inclination of the third molar buds should not be greater than 30° relative to the occlusal plane. Mandibular third molar should be in close proximity to the second molar roots to ensure adequate mesial drift of the third molar as it erupts. www.indiandentalacademy.com
  56. 56. Halderson, Higgins, Lehman and Smith agree that the optimal timing of the extraction of the second molar is when the crowns of the third molar are fully formed but before any radiographic evidence of root formation. Cryer and Fanning believe that the optimum age for this treatment is between 12 to 14 year and both stresses the importance of the position of the third molars. According to Wilson second molars should be extracted as soon as they erupt particularly in patients with severely tipped third molars. The third molars should be observed for 6 to 12 months for possible spontaneous correction. Rix suggested that the optimal time for extraction is as soon as the second molars erupt provided the mesial angulation of the 3rd molar is not greater than 45°. www.indiandentalacademy.com
  57. 57. Liddle on the other hand advocates early diagnosis and possible enucleation of the second molar (8-12 year). He notes that third molar would erupt by 13 years of age and are in occlusion by 14 years. Breakspear recommends not extracting second molar if the roots of the 3rd molars are half formed even if the latter have a favorable angulation. In summary, the consensus of opinion in both anecdotal and quantitative reports is that the optimal time of the second molar extraction, is as soon as it erupts if the third molar crown is complete, but before radiographic evidence of root formation, the angulation of the third molar bud plays a crucial role in the extraction decision. www.indiandentalacademy.com
  58. 58. Tulley believes that extraction of the second molar (both maxillary and mandibular) may minimize the deterioration of the incisor alignment which tends to occur in the middle and later teens period. Goldberg also referred to the extraction of the upper second molar when more space is required to get the first molar in Class I relationship and to avoid impaction of the third molar. Reid believed that this procedure causes decrease in the overbite, while premolar extraction tends to deepen the bite. He also suggested that a mesial exial angulation of the first molar is a favorable diagnostic factor when contemplating second molar extraction. www.indiandentalacademy.com
  59. 59. Removal of maxillary second molars instead of the premolars has been proposed by Graber for the correction of Class II div I in conjunction with extra oral appliances. In these cases the second molars are extracted and a lower fixed lingual arch is placed with occlusal rest on the mandibular 2nd molars until the maxillary third molars erupt and are on contact. Graber's rationale for this therapy is that only as much space as is required need to be used with the subsequent mesiovertical eruption of the maxillary third molar filling the gap. Graber believes that growth increments during therapy partly reduce the requirements for distal movements and that root movement requirements of the maxillary incisor do not appear to be as great with first premolar extraction. www.indiandentalacademy.com
  60. 60. According to Graber, 3 criteria should be met before this treatment is employed; a. There should be excessive inclination of the maxillary incisors with no spacing. b Overbite must be minimal or negative and c. Third molar should be present and in a good position to erupt. Goldberg also referred to the extraction of the upper second molars when more space is required to get the first molars in Class I relationship and to avoid impacting of the third molars. www.indiandentalacademy.com
  61. 61. Third molar extraction. The influence of the third molars on the alignment of the anterior dentition is controversial. There is no conclusive evidence to indict the third molars are being a major extiologic factor in post treatment changes in incisor alignment. The role of the mandibular third molars in the relapse of lower anterior crowding following the cessation of retention in orthodontically treated patients has provoked much speculation in dental literature. THE PRESENT CONTROVERSY In a survey I 1971, Laskin found that the third molars sometimes produce crowding of the mandibular anterior teeth. As a result of such opinion as Laskin reported, the removal versus the preservation of third molars became the subject of contention in www.indiandentalacademy.com dental circles.
  62. 62. The different view range between the extreme expresses in two different statement: 1. Third molars should be removed even on a pryphylactic basis because they frequently are associate with the future orthodontic and periodontic complication as well as other pathological condition. 2. There is no scientific evidence of a cause and effect relationship between the presence of third molars and orthodontic and periodontic problems. Third molar are teeth that are most often congenitally missing. Estimates of the percentage of the persons with one or more third molars missing range from 9% to 20%. www.indiandentalacademy.com
  63. 63. The average age for third molar crypt formation is 7 years. Its earliest occurrence was reported at 5 years and its latest at 15years. Bjork identified three skeletal factors that are separately influencing third molar impaction. 1. Reduced mandibular length measured as the distance from the chin point to the condylar head. 2. Vertical direction of condylar growth as indicated by the mandibular base angles. 3. Backward-directed eruption of the mandibular dentition determined by the degree of alveolar prognathy of the lower jaw. www.indiandentalacademy.com
  64. 64. In a case study of Jensen, there was more crowding in the quadrant with a 3rd molar present than in the quadrant with a 3rd molar missing. There was a mesial displacement of the lateral dental segments on the side with the third molar in the mandibular arch, but not in the maxilla. Bergstrom and Jenson concluded that the presence of a third molar appeared to exert some influence on the development of the dental arch, but not to the extent that would justify either the removal of the tooth germ or the extraction of the third molars. www.indiandentalacademy.com
  65. 65. Third molar enueleation at the age of 8 years has been practiced in England since 1936 by Henny and Morant. There are 3 major areas of economic concern in the third molar extraction: 1. Can the cost of the routine removal of the third molars as a preventive procedure be justified? 2. What are the risk and cost involved in the routine use of general anesthsia? 3. What are the added cost of hospitalization? www.indiandentalacademy.com
  66. 66. Pathological changes associated with third molars according to Lilly can be divided into two categories. 1. Those associated with erupted or partially erupted third molars (caries, periodontitis and other inflammatory condition, malcocclusion etc). 2. Those associated with un erupted or impacted teeth (follicular cyst, neoplasia). www.indiandentalacademy.com
  67. 67. A report presented by National Institute of Dental Research, 1979, stated; Crowding of lower incisor in produced by many factors which include tooth size, tooth shape, narrowing of the inter canine dimension, retrusion of incisors and growth changes occuring in the adolescent stage of development. Therefore, it was agreed that there is little rationale based on the present evidence for the extraction of the 3rd molar solely to minimize present or future crowding. Orthodontic therapy in both maxillary and mandibular arches may require posterior movement of both first and second molars by either tipping or translation which can result in the impaction of the third molars. To avoid impacting third molars and to facilitate retraction procedure. www.indiandentalacademy.com
  68. 68. ORTHODONTIC CONTRA INDICATIONS FOR EXTRACTION OF THIRD MOLARS. From an orthodontic stand point clinicians should attempt to persuade both the general practitioner and the oral surgeon to postpone the decision for the removal of third molars in the patients with malocclusion until the orthodontic treatment plan is completed. Certain situations need special attention When mandibular first premolars are extracted or one congenitally missing. If the orthodontic treatment plan calls for closure of the available space in the lower arch and no extraction approach in the upper arch, then the first molar relationship will become Class III. The maxillary second molar will have little or no occlusal contact with the opposing tooth that is the madibular second molars. The preservation and proper alignment of the mandibular third molars www.indiandentalacademy.com will allow them to interdigitate with the maxillary second molar.
  69. 69. When the orthodontic treatment plan calls for extraction of first or second permanent molars, particularly in the non-growing persons with Class II malocclusion or open bite tendencies. When the first or second molars have been extracted because of extensive caries and periapical involvement. In any situation which extraction of first or second permanent molars is considered, it is important to evaluate the size and morphology of the un erupted third molars by taking periapical radiograph before the extraction are recommended. One has to recognize that the presence of normally developed third molar does not automatically mean that the tooth will erupt into the line of occlusion. www.indiandentalacademy.com
  70. 70. Conclusion. The influence of the third molars on the controversial. There is no conclusive evidence to indict the third molars as being the major etiologic factor in the post treatment changes of incisor alignment. www.indiandentalacademy.com
  71. 71. Thank you www.indiandentalacademy.com Leader in continuing dental education www.indiandentalacademy.com