Extraction in orthodontics

1. 1 Extraction in orthodontics Extraction in orthodontics Prepared by: Prepared by: Dr Mohammed Alruby Dr Mohammed Alruby مكسبلام نوراتخت امك مكتاملك اوراتخا هقانا اضيا ملاكلاف Dr Dr. Mohammed Alruby . Mohammed Alruby E Extr xtraction in Orthodontics action in Orthodontics

2. 2 Introduction Reasons of extraction Analysis help in decision of extraction Effects of extraction Choice of tooth extraction Types of extraction Serial extraction Dr Dr. Mohammed Alruby . Mohammed Alruby E Extr xtraction in Orthodontics action in Orthodontics

3. 3 Introduction and history In corrective orthodontics or in camouflage treatment, extraction of certain tooth remains the most accepted method of gaining space in the arch The role of extraction in orthodontics was recognized by John Hunter 1771 in his book (natural history of teeth) 1889 Spooner advised the extraction of four premolars or 1st molars when defective 1859 Pierce writing in dental cosmos (advocated extraction in teeth crowding as a means for simplifying orthodontic procedure. The great extraction controversy is based on two schools: a-Adward Angle school b-Calvin Case school That is known after time as extraction debate of 1911 == Angle believed that full complement set of teeth should be present to improve function of masticatory muscles, he advocated expansion of arches in all patients == but Calvin Case (his former student) opposed the idea of non-extraction in all cases and contended that teeth extraction produces stable results == it is more than likely that Charles Tweed was familiar with Case’s concept of extraction because Tweed was extremely unhappy with the faces he was producing == the idea of treating cases again with extraction formed the basis of his further work, which lead to the Tweed philosophy % of extraction in UK: 1 ---- 1% 2 ---- 3% 3 -----4% 4 ----59% 5 ----13% 6 ----12% 7 ---- 7% Methods of good alignment: 1-Enlargement of arch form 2-Reduction in tooth size 3-Reduction in tooth number Reasons of extraction: 1-Arch length – tooth material discrepancy 2-Correction of sagittal inter-arch relationship 3-Abnormal size and form of teeth 4-Skeletal jaw mal-relationship Factors determining the needs for extraction: 1-Gonial angle 2-Axial inclination of lower incisors 3-Type and degree of crowding 4-Direction of growth 5-Differences in basal arch length 6-Age of patient 7-Thickness and distribution of the soft tissue covering facial bones Dr Dr. Mohammed Alruby . Mohammed Alruby E Extr xtraction in Orthodontics action in Orthodontics

4. 4 Analysis help for decision of extraction: 1-Arch analysis: -Bolton tooth size analysis -Howe’s analysis -Kesling diagnostic set up -Harvold symmetrograph -Peck and peck analysis 2-Cephalometric analysis: a-Tweed analysis: Tweed considered that, the lower incisors should be upright over the basal bone to achieve harmonious and symmetric occlusal and facial balance and gain a stable result Tweed triangle: TMA: 25 L1 – MP: IMPA: 90 L1 – FH: FMIA: 65 Role of FMA: 1-When FMA= 20 –30 degree, the correct position of L1 vary from 95 at 20 – to 85 at 30 Prognosis varies from excellent at 20 degree to good at 30 degree. When FMA below 20 the aim should not exceed the IMPA over 92 2-When FMA= 30 --- 35 degree the correct position of L1 vary from 85 – 80 degree Prognosis; good at 30 and fair nearest to 35 3-When FMA = 35 – 40 the prognosis for reducing the dento-alveolar prognathism vary: fair at 35 to unfavorable at 40 degree 4-When FMA is over 40 degree the prognosis is extremely unfavorable N: B: Tweed formula: -Non-extraction: FMA: 65 or greater and sufficient arch length -Borderline: FMA: 62 – 65 with sufficient arch -Extraction FMA: 62 or less b-Steiner analysis: He relates the lower incisors to NB line and use a linear measurement of 4mm and angular measurement of 25 degree Every degree of movement of lower incisors represent 2.5 mm in linear movement c-Holdaway analysis: He proposed that the lower incisors and pogonion be related to each other by the reference to NB line, both are linear measurement expressed in mm. the ratio of this measurements are important not their value Ratio: 2mm ----- very good facial balance 3mm ----- Holdaway will tolerate it 4mm ----- be extracts to return to 3mm Effects of extraction 1-Lower anterior face height and mandibular position: = Many orthodontists agree that non-extraction treatment is associated with downward and backward rotation of the mandible and increase the lower anterior facial height, also the Dr Dr. Mohammed Alruby . Mohammed Alruby E Extr xtraction in Orthodontics action in Orthodontics

5. 5 extraction treatment is associated with upward and forward rotation of the mandible and decrease the lower anterior facial height because extraction permits the posterior teeth to move forward and result decrease facial height = Schudy, among other recommended non-extraction approach for treatment of hypodivergant face, and extraction treatment in hyperdivergant facial type = Pearson, recommended extraction of premolars in patients with large AFH and steep MP 2-Soft tissues: = Orthodontist have long recognized that extraction especially the premolars have changes in soft tissue profile, these changes improve the profile and other called (orthodontic look) or dished – in profile, so in some cases may be prone to extract the 2nd premolars =Lo and Hunter studied the nasolabial angle changes that occurred in class II div 1 malocclusion: -NLA increase with increase in maxillary incisors extraction, the main ratio of increase was 1.6 to 1 -There is a strong and significant correlation between the change in the nasolabial angle and increase LFH = Looi and Mills studied the effect of extraction versus non-extraction on soft tissue profile and concluded that: 1-Following extraction of upper incisors in class II div 1, the upper lip drops back to a certain extent 2-Retraction of lower incisors affect the lower lip 3-The reduction of overjet has the effect of underlying both lips, this enables them to be held together without undue effort 4- There is a wide individual response in the reaction of soft tissue to change in the underlying hard tissues, so it is not possible to predict the effect on lips of a given movement of the teeth = Young and Smith, compare the soft tissues profile changes of extraction and non-extraction treatment patients, they concluded that: Non-extraction patients had less facial changes as a result of orthodontic treatment than group of extraction patients, the differences are: 6 degree in the nasolabial angle 1 to 2mm in upper lip protrusion 2mm to 3mm in lower lip protrusion = Drobacky and smith examined the change in facial profile during orthodontic treatment with extraction, and found that negative effect of extraction on the facial profile are false. Clearly the great majority of patients exhibit controlled amount of profile change improvement in facial esthetics = Talass et al, analyzed the soft tissue profile changes that result from retraction of maxillary incisors: 1-The upper lips were retracted mean 3.7 2-The anterior posterior position of the lower lip seems to be unchanged 3-Increase nasolabial angle by mean of 10.5 degree 4-Decrease the inter-labial gap by about 2.4mm 5-Increase the lower lip length by mean of 3.4mm 6-Increase upper lip thickness by mean of 2.3mm 7-Increase soft tissues lower face height Dr Dr. Mohammed Alruby . Mohammed Alruby E Extr xtraction in Orthodontics action in Orthodontics

6. 6 They concluded three measurements that were of clinical significance, these measurements are: Upper lip retraction Lower lip length The increase in the labiomental angle 3-TMJ: 1st premolars extraction is considered by many as an etiologic factor for TMJ disorders, Farar and Mc-Cathly, among others, believed that extraction of premolars during the course of orthodontic therapy are considered as predisposing factor for TMJ disorder as: 1-Extraction of premolars permits the posterior teeth to move forward resulting in decrease in the vertical dimension of occlusion, the mandible is then allowed to overclose 2-1st premolar extraction lead to over retraction of anterior teeth that lead to displace the mandible and condyles posteriorly. Posterior condylar displacement has long been associated with TMJ disorders = Kimiding, among others measured the anterior and posterior condylar spaces, and concluded that extraction of premolars did not affect the condyle position = Reilly et al, examined clinically the TMJ in extraction patients before and after treatment and concluded that the orthodontic treatment is not a causative factor to TMJ disorders Choice of tooth for extraction The decision regarding extraction of the teeth is governed by the following: 1-Condition of the teeth: Fractured teeth, hypoplastic teeth, grossly carious teeth beyond repair, periodontally affected teeth and teeth with large restoration are more favorable for extraction than sound healthy teeth In assessing the condition of the teeth, long term prognosis of the teeth is more important than their appearance which should be 2nd consideration 2-The position of crowding: Actually the 1st premolars are the teeth most commonly removed for relief of crowding, because they are located in the center of the dental arch and usually near to crowding whether anterior or posterior 3-Position of the teeth: Teeth which are severely rotated, grossly malposed and would be difficult to align are often the teeth of choice for extraction 4-Direction and amount of jaw growth 5-Amount of crowding 6-Molar relationship 7-Missing teeth in one side 8-Facial profile === class II extraction U4 and L5 but in class III extraction U5 and L4 9-Age of patients As general: the teeth to be extracted should provide the most favorable results with the least amount of tooth movement Dr Dr. Mohammed Alruby . Mohammed Alruby E Extr xtraction in Orthodontics action in Orthodontics

7. 7 Choose tooth for extraction 1-1st premolar (Tully): Most commonly extracted tooth for orthodontic treatment due to: a-Positioned almost near the center of each quadrant of arch b-Perfect contact between canine and 2nd premolar can obtained c-Maintain the vertical dimension d-After extraction of 1st premolar leaves 2nd and molars which form posterior segment the used as anchorage to allow extraction of anterior segment Indication: a-Moderate to severe crowding in both arches b-Severe proclination of anterior teeth (bimaxillary cases) c-As a part of serial extrcation d-In case of high anchorage demands Time of extraction: Four premolar extraction should not be extracted more than 3 weeks before starting active treatment to avoid mesial migration of posterior teeth 2-Second premolars: Tully and Logan 1047, Nance: first attention for extraction 2nd premolars in mild cases discrepancy 1974, Castro 1st advocated removal of 2nd premolars in orthodontic cases Indication: 1-mild arch length discrepancy less than 8mm 2-if mesial movement of 1st permanent molar is required 3-when creation of space for 2nd molar permanent is indicated 4-in cases of open bite closure in class I 5-when less maxillary incisors retraction is needed 6-when it is badly decayed, beyond the limit of orthodontic tooth movement Or take too much orthodontic procedures 7-when the facial contour is in good balance and proportion 3-1st permanent molar: Tully – Jensen: Considered as corner stone of dental arch Maintain the height of the bite The extraction of 1st molar is avoided for the following: When crowding is present in anterior segment so the 1st molar does not give good balance to relief crowding in anterior segment Lead to deepening the bite Masticatory efficiency is reduced Indication: Grossly decayed 1st permanent molar Periodontally weakened molar with poor prognosis Skeletal open bite cases in mixed dentition stage 4-Second molar extraction: Mogness The position of 2nd molar is at the end of the arch so that extraction is uncommon procedure Indication: 1-Where 3rd molar is present and with normal size and position Dr Dr. Mohammed Alruby . Mohammed Alruby E Extr xtraction in Orthodontics action in Orthodontics

8. 8 2-For distalization 3-Relief of impaction of 2nd premolar by distal movement of 1st molar 4-Severely carious, ectopically erupted 5-Open bite cases, that deepened the bite 6-Prevent 3rd molar impaction: where 3rd molar is upright or its long axis is not tilted mesially more than 30 degree to the long axis of 2nd molar. And also benefit after calcification of third molar crown or just after root formation, between 12 – 14 years Contraindication: 1-Missed 3rd molar or bicuspid 2-Severe bimaxillary protrusion 3-Severe anterior space deficiency Advantage: 1-Less surgical trauma 2-Better esthetic ----- reduce the probability of dish –in 3-More stability ----- reduce the probability of relapse 4-No problem in border line cases 5-Elimination of 3rd molar as a possible cause of relapse N: B: Criteria for 2nd molar extraction and replacement by 3rd molar are listed by Chimpan as follow: 1-The age of patient: if you decide to extract 2nd molar, they should extract before eruption of 3rd molar so 3rd molar will have great chance to erupt mesially in the space of 2nd molar 2-Size, shape and root area of 3rd molars: Third molar should be morphologically sufficient to serve instead of 2nd molar 3-The posterior alveolar process is not sufficient to accommodate the molars and crowding, malposition or impaction are expected 4-2nd molars are malposed, supra, infra occlusion or severely rotated 5-2nd molar caries beyond repair 6-3rd molar favorable angulation for eruption 7-Attempts to bring 2nd molar into proper occlusion will cause relapse of treated dentition 5-Third molar: Indication: 1-Most common one for impaction 2-Not likely to erupt into ideally position 3-Prevent late incisors crowding 4-Carious and difficult to restore 6-Upper incisors teeth: Max. central U1: Most prominent one due to its position in the arch rarely Indication: 1-Impacted one which cannot align properly 2-Severe fractured one 3-Grossly decayed tooth, cannot treated 4- Severely dilacerated root which cannot moved Max. lateral U2: Dr Dr. Mohammed Alruby . Mohammed Alruby E Extr xtraction in Orthodontics action in Orthodontics

9. 9 Teeth which has greatest variation next to third molars in form and number and eruption pattern. Indication: 1-Severely malposed tooth as when it is palatally blocked and more approximation between canine and incisors 2-Missing in one side so do balanced extraction on other side 3-Malformed tooth 4-When all teeth are more aligned except lateral incisors 7-Mandibular incisors: Indications: 1-When one of the incisors completely out of the arch with good alignment of other incisors and good light contact 2-Tooth size anomalies 3-Ectopic eruption of incisors 4-Moderate class III malocclusion 5-Incisors with poor prognosis Advantages: One way for preventing relapse is to extract incisors with extreme mal-positioning which limit movement of many teeth Contraindications: 1-Deep bite cases with horizontal growth pattern 2-Bimaxillary crowding 3-Cases with collapsed lower arch 4-Cases with narrowing inter-canine width 8-Canines: Have the largest and strongest root of all teeth that provide excellent anchorage Help to establish facial expression at corner of mouth Guide teeth to inter-cuspal position by canine guidance Indications: 1-Ectopic eruption or unfavorable impaction 2-When canine in one side is extracted so should extract other side to permit symmetry in arch 3-Tooth beyond restoration 4-When prolonged treatment time to be avoided N: B: Occlusion with incisors extraction may shows: 1-Tendency to cusp to cusp relationship on one side of the arch with what called slippage 2-A tendency for space opening after treatment especially when the basal arch is large 3-Tendency to increase overjet 4-Deep over bite may developed Types of extraction procedures -Balanced extraction -Compensatory extraction -Phased extraction -enforced extraction -therapeutic extraction Dr Dr. Mohammed Alruby . Mohammed Alruby E Extr xtraction in Orthodontics action in Orthodontics

10. 10 -Wilkinson extraction -Serial extraction 1-Balancing extraction: Extraction of another tooth on the opposite side of same arch to maintain symmetry in both arches 2-Compensatory extraction: Extraction of the tooth in opposite jaws to maintain buccal occlusion as in case of class I bi-max or crowding case, it is usually advised to extract in both arches to preserve the molars relationship 3-Enforced extraction: Extraction of decayed, fracture, impacted, tooth which enforced the orthodontic to extract. 4-Therapeutic extraction; Extraction of sound tooth for orthodontic purpose 5-Phased extraction: Extraction of one tooth in one arch few months earlier than other arch 6-Serial extraction: Extraction of deciduous tooth followed by permanent to relief crowding 7-Wilkinson extraction: Wilkinson advocated extraction of all 1st molars permanent between age of 8.5 to 9.5 years because these teeth highly prone to caries Benefits: -Prevent impaction of 3rd molar -Relief of crowding in dental arch -Decrease the incidence of caries Draw backs of Wilkinson extraction: -Relief of crowding only to certain extent -Mesial drifting of 2nd molars -Rotation of 2nd premolars -Lack of anchorage -Difficult define type of occlusion Contraindication to extraction 1-When the basal arch is large enough to accommodate all teeth in normal alignment 2-Slight crowding less than 3mm which can treat by other type of treatment 3-Early extraction in which the growth can change the pattern of face and arch Reasons against early extraction in orthodontic treatment 1-Continued growth of the jaws and there are some changes in face pattern 2-Relapse may show itself as spacing at the site of extraction due to functional forces and changes in the inter-dental ligament in spite of proper mechanotherapy Serial extraction Definition: Procedure which includes the extraction of certain deciduous teeth followed by permanent one to relief crowding. It is based on the assumption that, it is possible to predict at early age that, there will be lack of space to accommodate all of the permanent teeth. Dr Dr. Mohammed Alruby . Mohammed Alruby E Extr xtraction in Orthodontics action in Orthodontics

11. 11 Or: It is the planned program for reduction of deciduous dentition followed by reduction of permanent dentition to provide an adequate space for the remaining teeth to erupt in normal alignment Aim: = The aim of serial extraction is to provide an adequate space for permanent teeth to erupt into good alignment at early phase of mixed dentition, rather than allowing them to erupt abnormally in irregular position then extract to correct the condition at later age = this eliminate the needs for complicate treatment at later age History: 1743: Robert Bonon: first references for serial extraction 1929: Kjellgren: first coined the term of extraction (seweden) 1940: Nance: popularized the term of serial extraction, Hayes, Nance, considered the father of serial extraction 1970: Hotz (Rudolph Hotz of swizther land against this term and prefere guidance of eruption or active supervision of teeth by extraction Diagnostic procedure for serial extraction 1-Clinical examination of patient to assess soft tissue and skeletal background 2-Study model: -Assess dental anatomy -Assess inter-cuspation of teeth -Assess arch form -Evaluate the occlusion -Arch analysis: mixed dentition: Johnston& Tanaka 3-Radiograph: -Intra-oral -Extra-oral -Panoramic -Periapical -Cephalometry To detect the following: -Any pathosis -Missing or supernumerary teeth -Skeletal relationship -Soft tissue profile -Root development Indications: 1-When careful diagnosis predicts on arch length in adequacy through the following: -Lack of spacing or mild crowding in deciduous dentition -Deficiency of space for the lateral incisor to erupt in normal alignment -Premature loss of primary canine due to root resorption by pressure from erupting lateral incisors Dr Dr. Mohammed Alruby . Mohammed Alruby E Extr xtraction in Orthodontics action in Orthodontics

12. 12 -When radiograph shows an uneven resorption of deciduous teeth roots or shows lack of space among the erupting teeth -When mixed dentition analysis reveals arch length deficiency 2-When no discrepancies in the dental arch relationship that contraindicate the serial extraction = this is not an absolute rule and cannot applied in all cases, but the correction of dental arch relationship usually requires good control of space, and the risk of space loss during serial extraction make it more suitable for class I malocclusion = only few cases of dental arches mal-relationship can meet all the requirement of serial extraction 3-When the radiograph reveals that, all erupting teeth in good conditions and in correct eruptive path 4-Some cases of mild crowding in mandibular arch in class II 5-Some cases of mild crowding in maxillary arch in class II = if serial extraction to be carried in class II or class III, it must apply with greater cautions 6-Mayne reported that, serial extraction must be largely applied to class I malocclusion and should limited to those cases that have a good face 7-Eisner listed a number of rules that govern the decision of serial extraction: Rule 1: there must be class I molar relationship bilaterally. Rule II: the facial skeleton must be balanced anterior posterior, vertically and medio- laterally Rule III: the space deficiency must be at least 5mm in four quadrant Rule IV: the midline must be coinciding Rule V: the midline must be neither open bite nor deep bite The more the case meet these requirements, the more successful procedure and the reverse is true Contraindication: 1-Class I malocclusion when there is slight crowding which can be corrected by: -Distalization: upright of tipped U and L 6 and corrected rotation -Later growth = the crowding is less than 5mm in all quadrant 2-Class II and class II div 2 malocclusion, where the problem will need comprehensive treatment at later age 3-Presence of facial a symmetry and midline deviation that will require complicated treatment at later age 4-When Oligodontia or other deficiencies of the teeth are present 5-Delayed eruption of the teeth or abnormal eruptive path 6-In the presence of midline diastema 7-Deep over bite and open bite which should be treated first 8-When fixed appliances cannot be used to avoid arch collapse Some important consideration before serial extraction 1-Indication for serial extraction are depends mainly on the leeway space. = careful assessment of arch length and leeway space by using all available diagnostic aids (cast, periapical, and panoramic radiograph) is necessary = the severity and the amount of crowding should be considered = the labial tipping of permanent incisors Dr Dr. Mohammed Alruby . Mohammed Alruby E Extr xtraction in Orthodontics action in Orthodontics

13. 13 = the occlusal relationship of 1st permanent molars 2-There are marked individual variation in the arch size and leeway space which may result in favorable or unfavorable arrangement of permanent teeth. 3-Children on serial extraction is plasticized according to Dewel usually shows in addition to crowding of incisors = premature loss of deciduous canines = sometimes midline deviations 4-In class I malocclusion, serial dentition proceeds active orthodontic treatment while in class II malocclusion, it should be a part of the 1st stage of treatment 5-Growth changes should be watched to determine whether growth can provide an adequate space for permanent teeth and thus the needs for extraction is eliminated 6-Before serial extraction is undertaken, it is important to check the occlusion to determine whether the 1st permanent molars are tipped or rotated and whether the correction of condition can provide adequate space for aligning teeth, thus the needs for extraction is eliminated Some important consideration during serial extraction 1-Serial extraction requires serial observation both clinically and radiographically to determine the relative positions of unerupted teeth to the alveolar crest and to detect any conditions might interfere with eruption 2-The space created by extraction of deciduous teeth should be kept under strict supervision to prevent space loss before eruption of permanent successors 3-The rate and amount of root development of permanent successors must put in mind = generally, teeth emerge into the mouth when about ½ to ¾ of their roots are completely found 4-More cautions and more precise space control is required in the mandibular arch more than in maxillary arch as reported by Morrees and his co-workers 5-The rate and direction of growth must be considered = the amount of inter-canine width increase cannot be predicted with any degree of accuracy 6-Flush terminal plane and relationship of newly erupted U6 and L6 will followed by mesial shifting in the leeway space for the purpose of occlusal adjustment 7-The relative position of 1st premolar to the permanent canines should be considered: a-When radiographic examination showed that the permanent canines might erupt before the 1st deciduous molar, extraction of primary canine to prevent permanent canines from erupting before 1st premolar which if occurs ---------- impaction of 1st premolars b-When the permanent canines tend to erupt labially or lingually, the primary canines should be extracted then followed by extraction of 1st premolars c-When any integrity factors are detected such as bulk of alveolar bone or fibrous gingiva, they should be surgically removed to facilitate eruption Benefits of serial extraction 1-To ensure eruption of permanent teeth in favorable direction and good alignment 2-To avoid loss of labial alveolar bone, when the teeth erupt in labioversion due to lack of space 3-To reduce malposition of individual teeth Dr Dr. Mohammed Alruby . Mohammed Alruby E Extr xtraction in Orthodontics action in Orthodontics

14. 14 4-To reduce treatment time when major orthodontic treatment is required at later age, and in some cases to eliminate the need for treatment at later age Timing of extraction 1-Serial extraction usually starts in early mixed dentition 2-It is not possible to predict the exact time of teeth eruption from the root length or from the eruption table, however the root length is used as diagnostic criteria 3-The deciduous 1st molars should not extract before one half of 1st premolar root is formed 4-The deciduous canines should not remove until ½ of the permanent canine root is formed = As a general rule, deciduous tooth should not be extracted until ½ to ¾ of the root of its permanent successors is completely formed Methods of serial extraction 1-Nance method: 1949 : D 4 C = Nance analyzed arch length and found that, the difference in the leeway space may varies from 0 to 4mm between the deciduous and permanent teeth = the following method was introduced by Nance to determine the relative mesio-distal width of deciduous and permanent teeth in mixed dentition: a-Measure with a pair of divider the mesiodistal width of the two deciduous molar and the deciduous canine or the amount of space which these were occupied in the dental arch b-Measure the greatest mesiodistal width of premolars and permanent canine as shown on roentgenogram c-Compare the measurements, the difference in the leeway space Nance obtained the following measurements from the mandibular cast in mixed dentition: a-The outside measurement: measure the arch parameter from the mesio- buccal surface of 6 on one side to mesiobuccal surface of 6 on the other side, by adapting 0.010 inches’ brass wire on the buccal surface of the teeth so that, it touches the middle 1/3 of the teeth b-The inside measurement: with a pain of divider, measure from the mesiolingual surface of 6 on one side to the apex of inter-dental papilla between mandibular central incisors == after measurements: when the arch length is deficient, serial extraction is indicated 2-Dewel’s method: 1978: C D 4: Dewel describe 3 stages in serial extraction: a-Early extraction of deciduous canine to provide a space for lateral incisors to assume normal position b-Extraction of 1st deciduous molars to permit early eruption of 1st premolars c-Extraction of 1st premolar to allow space for canine to erupt in the space occupied by 1st premolars = the intervals between these stages and the sequence of eruption various with the individual patient from 6 months to 1 year = the patient should keep under periodic observation at 2:3 months’ interval to supervise the space and extent of growth 3-Tweed method: 1966: D C 4: When diagnosis showed that there is discrepancy between the size of the teeth and the size of basal bone, and the patient was between 7.5 and 8.5 years, serial extraction is performed as follows: Dr Dr. Mohammed Alruby . Mohammed Alruby E Extr xtraction in Orthodontics action in Orthodontics

15. 15 a-At 8 year of age, all the four 1st primary molars are extracted = if the mandibular permanent incisors are not blocked out or severely crowded, Tweed maintain the deciduous canine in position, so that, the eruption of permanent canines will not be listened b-When the premolars teeth erupt to the level of crest of alveolar mucosa, they are extracted c-The deciduous canines are also extracted at this time: = if the 1st premolars are extracted 4 to 6 months prior to eruption of permanent canines, the permanent canines usually shift posteriorly and erupt in the space for mainly occupied by the extracted 1st premolars = the mild irregularities of mandibular incisors are usually self-corrected N: B: 1- the second deciduous molars should be maintained in the arch to prevent mesial shifting of U and L 6 2-a profile roentgenogram is taken and traced: -After 6 to 12 months a second roentgenogram is taken and traced -Then the two radiographs are superimposed by taken the S – N line as references A-If the growth of the mandible appears to be more vertical (downward or downward and backward) the point B cannot be expected to advance during treatment so that headgear is necessary to be applied on maxillary arch just after removal of 1st premolars in order to move the A point posteriorly to reduce the ANB angle B-If tracings showed that growth of mandible is more forward (horizontal) this favorable growth and no need for headgear treatment. The prognosis is more favorable 4-Esner method: The procedure consists of the four following steps: 1-Extraction of primary lateral incisors as permanent central erupt 2-Extraction of primary canine as the permanent lateral erupt 3-Extraction of primary 1st molar usually 6 to 12 month before time of exfoliation, at the point when the underlying premolars have one half to two third of their root is formed 4-Extraction of 1st premolars before eruption of permanent canines Dr Dr. Mohammed Alruby . Mohammed Alruby E Extr xtraction in Orthodontics action in Orthodontics