Prof. Maher A. Prof. Maher A. FoudaFouda

Prepared by:- Bilal A.M.Prepared by:- Bilal A.M.Faculty of dentistry-Faculty of dentistry-

Mansoura university - Mansoura university - EgyptEgypt

A 13-year-old girl who did not have the benefit of serial extraction and early treatment

A 13-year-old girl who had the benefit of serial extraction and early treatment.

SERIAL EXTRACTIONThe combination of preventive therapy and orthodontics, is essential during development and the guidance of the child's dentition towards an adult occlusion of good quality. It is for this reason that child dental care and orthodontics form an entity.Only with such basic thinking in mind is it possible to guide development towards an optimal form and function of the dentition.

So, the question of serial extraction arises when the first permanent tooth erupts and, if it is to be considered, it is during the period of six to twelve years of age.

Serial extraction is an interceptive procedure designed to assist in the correction of hereditary tooth-size Jaw-size discrepancies. It improves the alignment of the teeth when they emerge into the oral cavity.

It does not replace mechanotherapy but if it done properly in carefully selected patients, it reduces treatment time, the cost of treatment, discomfort of the patient at the sensitive teenage period and time lost by the patient and parents.

Both Hotz and Kjellgren stated that the goal of serial extraction is to create a modified occlusion with less than the normal complement of teeth in order to assure better function,improved aesthetics and stability throughout life.

(Brouwer, 1986)The principle of early treatment, associated with theextraction of primary teeth followed by the removal of permenant teeth firstly described by Robert Bunon in 1743. Kjellgren's term " Serial extraction" which he introduced in 1929, is somewhat dangerous because it tends to create a misconception of simplicity. It is , in fact, misleading . It implies that there is nothing moreinvolved than the more extraction of teeth. So, Hotz's term (1947) "Guidance of Occlusion" is better.

CRITERIA FOR SERIALEXTRACTION (lndications)1. Class I malocclusions are ideal for serial extraction because the dentition is basically in a favorable relationship and successful treatment is possible with a minimum of mechanotherapy.2. A true,relatively severe, hereditary tooth-size jaw-size discrepancy. (10 mm or more).3. A mesial step mixed dentition developing into a class I permenant relationship.4. A minimal overjet relationship of the incisor teeth.5. A minimal overbite of incisors.

6. A Facial pattern that is class I maxillary mandibular alveolodental protrusion.7. A Facial pattern that is class II maxillary alveolodental protrusion (with extraction of the two maxillary first premolars).8. Class I maxillary mandibular prognathism with severe crowding.9. Class II maxillary prognathism.(Serial extraction in class II malocclusions aids in the correction of tooth-size jaw-size discrepancy but not necessarily in the correction of a class II relationship).

10. In high angle cases (steep mandibular plane), associated withsevere crowding.11. Premature loss of anterior teeth B,C.12. Lingual eruption of anterior teeth.13. Unilateral deciduous canine loss and shift to the same side.14. Ectopic eruption.15. Ankylosis.16. Abnormal resorption.

CONTRA INDICATIONS OF SERIAL EXTRACTION1. Class III malocclusions are not suitable for serial extraction.2. A Facial pattern that is class I maxillary mandibular alveolodental retrusion.3. A Facial pattern with Class II mandibular alveolodental retrusion.4. Class I maxillary mandibular retrognathism.5. Class II mandibular retrognathism.6. In low angle cases (low mandibular plan angle).7. Class I malocclusion cases where the lack of space is slight and the teeth are only slightly crowded.

8. When there are teeth missing from the dental arch.9. Deep overbite cases.10. Anterior openbite cases.11. When fixed appliance cannot be used to avoid arch collapse.

OBJECTIVES OF SERIALEXTRACTION1- Serial extraction allows teeth to become aligned when they emerge into the oral cavity rather than to stay in a crowded unfavorable condition for several years.2- It makes the treatment easier and the mechanotherapy less complicated.3- It makes the treatment less extensive and shorter in time(especially during the teenage period).4- To avoid loss of labial alveolar bone.

5- To reduce malposition of individual teeth.6- It encourages eruption of permenant teeth in favorable direction.7- To minimize unfavorable sequalea as root resorption ,decalcification and soft tissue proliferation that so ofen accompany protracted period of appliance therapy.8- It reduces the cost of treatment.

EXAMINATION AND EVALUATIONSerial extraction should never be initiated without a comprehensive diangosis, which is established by a thorough examination and evaluation of the diagnostic records.

I-Clinical AnalysisThe hereditary tooth-size jaw-size discrepancies must be differentiated from crowded dentitions resulting from factors that are more enviromental in nature. It is quite likely that true hereditary crowding will be treated with the aid of extractions and, if discovered early , with serial extraction. On the other hand, crowding resulting from enviromental factors may be treated without extractions.

A-Hereditary crowding

The signs of a true hereditary tooth-size jaw-size discrepancy may be outlined as follows:1. Maxillary mandibular alveolodental protrusion without interproximal spacing.2. Crowded mandibular incisor teeth.3. A midline displacement of the permanent mandibular incisors, resulting in the premature exfoliation of the primary canine on the crowded side.4. A midline displacement of the permanent mandibular incisors with the lateral incisors on the crowded side blocked out, usually lingually but occasionally labially .

5. A crescent area of external resorption on the mesial aspect of the roots of the primary canines , caused by crowded permanent lateral incisors.6. Bilateral primary mandibular canine exfoliation, resulting in an uprighting of the permanent mandibular incisors ; this, in turn, increases the overjet and/or the overbite .7. A splaying out of the permanent maxillary or mandibular incisor teeth due to the crowded position of the unerupted canines.8. Gingival recession on the labial surface of the prominent mandibular incisor.9. A prominent bulging in the maxilla or mandible due to the crowding of the canines in the unerupted position.

10. A discrepancy in the size of the primary and permanent teeth, reducing the leeway space .11. Ectopic eruption of the permanent maxillay first molars, resulting in the premature exfoliation of the primary second molars ; this indicates a lack of development in the tuberosity area.12. A vertical palisading of the permanent maxillary first, second, and third molars in the tuberosity area, again indicating a lack of jaw development.13. Impaction of the permanent mandibular second molars in the absence of treatment.

B- Enviromental crowding : It may result under thefollowing condition :1. Trauma.2. Iatrogenic treatment.3. A discrepancy in the size of individual teeth.4. A discrepancy between mandibular tooth size and maxillarytooth size and maxillary tooth size.5. An aberration in the shape of teeth.

6. An aberration in the eruptive pattern of the permanent teeth.7. Transposition of teeth.8. Uneven resorption of primary teeth.9. Rotation of teeth.10. Suppression of primary teeth.11. Premature loss of primary teeth resulting in the reduction of arch length due to subsequent drifting of permanent teeth .12. A reduction of arch length due to interproximal caries in the primary teeth.13. Emergence sequence.14. Exfoliation sequence of primary teeth.15. Prolonged retention of primary teeth.

II Diagnostic records :A complete set of diagnostic records is required including , intaoral radiographs , cephalometric radiographs , facial photographs , study models and intraoral slides of the dentition.1- Intraoral radiographA complete series of periapical radiographs or a panoramic radiographs must be taken for the following:1. Protection of the patient and the orthodontist.2. Detection of congenital absences of teeth .3. Detection of supernumerary teeth.4. Evaluation of the dental health of the permanent teeth,especially the first molars.

5. Detection of pathologic conditions in the early stages.6. Assessment of trauma to the teeth after an injury.7. Detection of evidence of a true hereditary tooth-size jawsize discrepancy such as the resorptive pattern on the mesial of the roots of the primary canines.8. Determination of the size, shape, and relative position of unerupted permanent teeth.9. Evaluation of the eruptive patterns of unerupted permanent teeth.10. Calculation of the total space analysis .

11. Detection of root resorption before, during, and after treatment.12. Evaluation of third molars before, during, and after treatment.13. Final appraisal of the dental health after orthodontic treatment.14. Determination of dental age of the patient by assessing the length of the roots of permanent unerupted teeth and the amount of resorption of primary teeth.

Dental Age AnalysisDental age is determined by two ways ; tooth eruption and root formation. Dental age, assessed particularly by root length, is an essential requirement in the decision of a serial extractionprogram. Serial extraction too early in the primary dentition can delay the eruption of permenant teeth. In case of early extraction of the primary molars, fanning reported an initial spurt in eruptionof premolars. This leveled off and the tooth then remained stationary erupting later than its antimare with a normally shedded primary tooth.

If serial extraction is initiated with extraction of the primary canines, the length of the roots of the premolars is not an important consideration. If, however, one is contemplating initiating serial extraction by the removal of the primary first molars, then the length of the root of the premolar is an important consideration and guide the commencement of the procedure.The relative eruptive rates of the permenant canines and first premolars influence the decision as to which primary teeth one should extract.

If an examining periapical radiographs one observes the mandibular first premolar crown ahead of the permenant mandibular canine crown, the premolar with less than half its root formed, and the madibular incisors crowded, then the primary canine should be extracted to relieve the crowding. The primary molar should be left until the first premolar has attained half its root length. If on examining the radiographs one observersthe premolar crown even with the canine crown, the premolar with half its root formed, and an alveodental protrusion, then the primary first molar should be extracted to encourage the emergence of its successor.

2- Cephalometric radiographs :Sound orthodontic treatment, including serial extraction, is based on the intelligent use of cephalometric radiographs andanalysis. They are utilized for the following :1. Evaluation of craniofaciodental relationships prior to treatment.2. Assessment of the soft tissue matrix.3. Calculation of tooth-size jaw-size discrepancies.4. Determination of mandibular rest position.5. Prediction of growth and development.

6. Monitoring of skeletodental relationships during treatment.7. Detection of pathologic conditions before, during, and after treatment.8. Assessment of trauma after facial injuries.9. Study of relationships prior to , immediately following, and several years after treatment for the purpose of long-rangeimprovement in treatment planning.10. Classification of facial patterns.

proportional facial analysisThe proportional facial analysis is basically a classification of facial patterns based on the Steiner and the Merrifield and Tweed cephalometric analysis , and especially on the counterpart analysis of Enlow . It includes an evaluation of the following relationships:Anterior cranial base (1,2).Posterior cranial base (2,3).

Cranial base angle (1,2,3).Ramus of the mandible (3,4).Corpus of the mandible (4,5).Gonial angle (3,4,5).Nasomaxillary complex (6,7,8,9).Maxillary dentition (10,11).Mandibular dentition (12,13).

To determine the relationship between the facial structures and the cranium, between the maxilla and the mandible, between the maxilla and the maxillary dentition, between the mandible and the mandibular dentition, between the maxillary dentition and the mandibular dentition, and between the soft tissue profile and the underlying hard tissue structures.

3- facial photographs :Ortial , (1995) stated that; the vertical skeletal pattern is afactor that makes malocclusions with the same tooth arrangment very different.Facial patterns play an extremely important role in serialextraction in the following :

1. Evaluation of craniofacial relationships prior to treatment.2. Assessment of soft tissue profile.3. Proportional facial analysis.4. Total space analysis.5. Occlusal curves analysis.6. Monitoring of treatment progress.7. Study of relationships prior to , immediately following , and several years after treatment to improve treatment planning.

American Board of Orthodontics requirements for facial photographs. (From American Board of Orthodontics:Specific instructions for candidates, St Louis, 1998, The Board.)Requirements:-Quality, standardized facial photographic prints either in black and white or color-Patient's head oriented accurately in all three planes of space and in the Frankfort horizontalplane-One lateral view; facing to the right; serious expression; lips closed lightly to reveal muscleimbalance and disharmony

-One anterior view; serious expression-Optional: One lateral view and/or one anterior view with lips apart-Optional: One anterior view, smiling-Background free of distractions-Quality lighting revealing facial contours, with no shadows in the background.-Ears exposed for purpose of orientation-Eyes open and looking straight ahead; glasses removed

4- Intraoral p h o t o g r a p h s :Treatment could be performed without the use of colortransparencies of the dentition. However, they are extremely valuable for one reason: to record, for future reference, the structure of the enamel. This is particularly important when bands or brackets are removed.

It is quite possible that the orthodontistcould be accused of producing decalcification, or an imperfection in the enamel, that was already present before treatment was begun. Intraoral photographs add the dimension of color to the records, which aids in assessing and recording the health or disease of the teeth and soft tissue structures.

5- Study models:Study models provide a three- dimensional record of the dentition and are essential for many reasons. They are used to :1. Claculate total space analysis.2. Assess and record the dental anatomy.3. Assess and record the intercuspation.4. Assess and record arch form.5. Assess and record the curves of occlusion (occlusal curves analysis).

6. Evaluate occlusion, with the aid of articulators .7. Measure progress during treatment.8. Detect abnormalities .9. Provide a record before , immediately after, and several years following treatment for the purpose of studying treatment procedures.10. Assess in detetmination of 3 , 4 , 5 by mixed dentition analysis .

Mixed dentition analysisThis analysis aids in determination of cases indicated for serial extraction. The purpose of this analysis is to evaluate acurately as possible, future crowding in the permenant dentition using a prediction of mesiodistal width of the permenant canines and premolars. The value obtained is added to the already known measurement of the permenant incisors . This represents space required . The resulting calculation is subtracted from the arch circumference of space available. If the result is significantly negative, future crowding can be predicted.

Many methods of mixed dentition analysis have been suggested. They are :1-Nance Analysis (1947) :He found that the combined width of the primary canine and primary molars averages l .7mm more in the mandibular arch and 0.9mm more in the maxillary arch, than the combined widths oftheir successors measure.2-Moyers Analysis (1963) :He found that the approximated size of the canines and premolars is calculated by measuring the mesiodistal width of erupted permenant incisors. Prediction is done on the propability charts.

3- Sim's Analysis (1972) :He pointed out that various tooth size charts indicated that the mesiodistal width of a first premolar is nearly one third of the combined mesiodistal widths of the cuspid and bicuspids in a quadrant. This hold true for the maxillary and mandibular arches.N.B : The width of the first premolar determined radiographically using the long cone parallel techinque.

4- Johnson-Tanaka- A n a l y s i s (1974) :They found that half the mesiodistal width of the mandibular incisors measured on the cast plus 11 mm. For the maxillary arch and 10.5mm. for the mandibular arch equal to the mesiodistal width of unerupted cuspid and bicuspids.

5 - A b o u l - A z m - F o u d a ' s A n a l y s i s (1989):-It is a new equation for predicting the combined mesiodistal width of unerupted cuspid and bicuspids.- For the upper arch :mesiodistal dimension of cuspid and bicuspids =(buccolingual dimension of first permenant molar X 2) - 1 .- For the lower arch :mesiodistal dimension of cuspid and bicuspids =buccolingual dimension of first - permenant molar X 2.

Categories Of Serial Extraction

The best results can be achieved when disturbing factors are minimal. Flexibility in thinking is necessary, diagnosing every case individually, and each time the patient is seen it needs to be carefully assessed.

There are three categories which are:1. A period of interceptive guidance. Extending approximately 5years, from age 7.5 to 12.5 . This consists entirely of the guidance of occlusion, including serial extraction, and is the most ideal service that one can provide. The results are achieved without multibanded mechanotherapy.

2. An initial period of interceptive guidance, extending approximately 4 years , from age 7.5 to 11.5 , plus a second period of multibanded treatment extending approximately lyear(from 11.5 to 12.5).3- An initial period of interceptive treatment, extending approximately 1 year, from 8.5 to 9.5 plus a period of interceptive guidance extending approximately 2 years,from 9.5 to 11.5, and a second period of multibanded treatment extending approximately 1.5 years, from 11.5 to 13.

GENERIAL TECHNIQUES FOR SERIAL EXTRACTION

1-Hotz Method:It is the basic procedures for serial extraction :1.Extraction of deciduous canines. This is generally followed by spontaneous correction of the position of the permanent incisors.2. Extraction of deciduous first molars, to encourage early eruption of first premolars.3. Extraction of first premolars.This method proposed by Hotz, (1947).(Brouwer, 1986)

2- Nance Method:Nance showed that the difference of leeway space may vary from 0 to 4 mm. Between the deciduous and permenant teeth in the mixed dentition.When we see that there is a significant crowding , we begin our planned program of guided extraction in three stages :1. Removal of deciduous canines at 8 - 9 years:The immediate purpose is to permit the eruption and optimal allignment of the lateral incisors, prevention of the eruption of the maxillary lateral incisors in lingual cross-bite or the mandibularincisors in lingual malposition.

But this improvement is gained at the expence of space for the permenant canines vitally important is the fact that the correct lateral incisor position prevent the mesial migration of the canines into severe malposition that willrequire treatment with mechanotherapy later.2- Removal of the first diciduous molars at 9-10 years:This is done to accelerate the eruption of the first premolars ahead of the canines. Generally speaking the first deciduous molars are removed 12 months after the deciduous canines. Thus,first deciduous molars removal would be when the roots of the first premolars have half root calcification.

Sometimes the removal is done earlier in the mandibe than in the maxilla to enhance the early eruption of first premolars.3- Removal of the erupting first premolars :The purpose of this step is to permit the canine to drop distally into the space created by the extraction. The extraction of first premolar happens more frequently in the maxillary arch than in the mandibular arch.

The reason is the eruption sequence, which upper first premolar eruption is ahead of lower one. Sometimes, while removing first deciduous molars we enucleate the unerupted first premolars (usually in the lower arch).Sometimes , it becomes necessary to remove the mandibular second deciduous molars to permit the first premolars to erupt.

3 - Tweed's orthodontic guidance:When diagnosis shows that a discrepancy between tooth and jaw-size, and the age of the patient is between 7 - and 8 - years ,serial extraction is performed as following :1- At age 8 years; all 4 deciduous first molars are extracted. If the permenant incisors are not severely crowded, the deciduous canines mantained in position so that the eruptionof the permenant canines will not be hastened.

2. When the first premolars erupt to about the level of the crest of the alveolar mucosa they are extracted. The deciduous canines are also extracted at this time. If the first premolars are extracted 4 to 6 months prior to the eruption of the permenant canines, the permenant canines usually shift posteriorly and erupt in the space left by the extracted first premolars.The second deciduous molars should be maintained in the arch to avoid mesial shifting of first permenant molars.

CLASS 1 TREATMENTThe classic procedure of serial extraction has been the elimination of the primary canines, primary first molars, and permanent first premolars.This has been the most popular and widely used procedure.

serial extraction in treatment of different cases of class I :A- CASES WITH ANTERIOR DISCREPANCY : CROWDING- Treatment Procedure:1. Extraction of the primary canines:

If we found severe crowding, a developing Class Imalocclusion, a favorable overjet overbite relation of the incisor teeth, and an ideal orthognathic facial pattern. On examining the one radiographs, can note a crescent pattern of resorption on the mesial of the primary canine roots.

This is an indication of a true hereditary tooth-size jaw-size discrepancy. It signifies that the first premolars are emerging favorably, ahead of the permanent canines. None of the unerupted permanent teeth have reached one half root length. Because of this, we would not extract the primary first molars. The primary canines should be extracted to relieve the incisor crowding.

2. Extraction of the primary first molars :The incisor crowding has improved ; the overbite has increased, and the extraction site is reduced in size. The radiographs reveal that the first premolars have reached one half root length. It is now time to extract the primary first molars toencourage the eruption of the first premolar teeth.

3. Extraction of the first premolars :Since the permanent canines have developed beyond one half root length, indicating that they are prepared to accelerate their eruption, the premolars are extracted.

4. Multibanded treatment:To treat the typical result of serial extraction, a relatively deep overbite with a distoaxialinclination of the canines, a mesioaxial inclination of the second premolars, a Class I molar relationship, an improved alignment of the incisors ; and residualspaces at the extraction sites.

5. Retention :When multibanded mechanotherapy is completed.

A, Lateral view. B, Anterior view. C, Occlusal view of mandibular dentition 18 years after treatment.

B. CASES WITH ANTERIOR DISCREPANCY ;ALVEOLODENTAL PROTRUSION:- Treatment Procedure :1. Extraction of the primary first molars:

When we found a minor irregularity of the incisor teeth , the crowns of the first premolars and canines are at the same level, the canines are beyond one half root length and are erupting faster than the premolars, the first premolars have one half their root length developed, the primary first molars should be extracted toaccelerate eruption of the first premolars.

2. Extraction of primary canines and first premolars:When the first premolars have emerged sufficiently, they areextracted along with whatever primary canines remain. No effortis made to prevent lingual tipping of the incisor teeth since the objective is to reduce the alveolodental protrusion.

3. Multibanded treatment:The dentition is aligning itself. Very little mechanical treatment will be required.

4. Retention :Retention in the mandible is less crucial since there was minimal irregularity before treatment.

C. CASES WITH MIDDLE DISCREPANCY : IMPACTED CANINES :- Treatment Procedure :1. Extraction of the primary first molars:When the tooth-size jaw-size discrepancy is severe , causing premature exfoliation of the primary canines and the radiograph will reveal that the first premolars are ahead of the canines

in eruption and have attained one half their root length, we must begin with extraction of the primary first molars. The impacted permanent maxillary canines may cause severe splaying of the maxillary incisors to such an extent that the lateral incisors do not contact the primary canines .

In this situation extract the primary first molars to encourage the first premolars to emerge as early as possible. The canines will then have space to migrate away from the apices of the incisors and begin their eruption into the oral cavity. In this instance we should be concerned more with incisor irregularity.

2. Extraction of the first premolar:Since the permanent canines have developed beyond one half root length, indicating that they are prepared to accelerate their eruption, the premolars are extracted.

3. Multibanded treatment.

4. Retention.

D- CASES NEED PREMOLAR ENUCLEATION:Advantages:1- Enucleation of premolars can be used to minimize the severity of crowding in arch-length deficiency cases.2- It can minimize the severity of the malocclusionsimplifying appliance therapy if proper diagnosis and good surgical technique are employed.3- The mandible tends to rotate in a counterclockwise manner following enucleation of four first premolars without appliance therapy.

4- Enucleation offers autonomous adjustment of the mandibular incisors and root positioning ofmandibular cuspids.5- Enucleation cases usually require fewer traumatic surgical procedures and less supervision by the orthodontist.

(Ingram, W76)

I. CASES NEED ENUCLEATION IN THE MANDIBLE :- Treatment Procedure :l. Extraction of the primary first molars and enucleation of the mandibular first premolars :

If it is evident that the canines will emerge into the oral cavity ahead of the first premolars, we can extract the primary first molars and enucleate the first premolars. This will encourage distal migration of the canines as they erupt.

2. Extraction of the primary maxillary canines and maxillary first premolars:In the maxilla the first premolars usually emerge before the canines. Therefore enucleation is less likely to be indicated.

3. Multibanded treatment

4. Retention.

I I . CASES NEED ENUCLEATION IN THE MAXILLA AND MANDIBLE- Treatment Procedure :1. Extraction of primary canines and primary first molars and enucleation of the first premolars:On occasion the canines in both the maxilla and the mandible will erupt prior to the first premolars. We must extract the primary canines and first molars and enucleate the first premolars.

2. Multibanded treatment.

3. Retention.

E. CASES IN WHICH ENUCLEATION IS AVOIDED :- Treatment Procedure :1. Extraction of the primary first molars:When the permanent canines are erupting ahead of the first premolars and if there is an opportunity to place multibanded appliances at the completion of serial extraction, enucleation of the premolars should be avoided.

When the first premolars have attained one half their root length, the primary first molars should be extracted.

2. Extraction of the primary maxillary canines,maxillary firs premolars, and primary mandibular second molars:Some 6 to 9 months later , when the emerging mandibular first premolar appears to be obstructed by the mesial contour of the primary second molar, we should extract the offending tooth. However, this sequence is usually not necessary in the maxillary dentition.

3. Extraction of the mandibular first premolars:When these teeth emerge sufficiently, they are extracted.

4. Multibanded treatment

5. Retention.

CLASS II TREATMENT PLAN

Serial extraction can be an important part of Class II treatment , it must be stressed that , serial extraction does not replace mechanotherapy.

TREATMENT PLAN

1. Initial period of interceptive treatment:During this period, which may extend 1 to 1.5 years, the primary first molars and maxillary first premolars are extracted as early as possible. This provides space for retraction of the permanent maxillary anterior teeth. Bands are placed on the premanent maxillary incisors and first molars and on the primary second molars. With a maxillary edgewise arch and an anterior high pull headgear, the maxillary incisors are retracted, intruded, and torqued. This reduces the overjet and overbite.

The primary objective of the initial period of interceptive treatment is to decrease the vulnerability of and possible injury to the maxillary incisors. In the mandible the primary canines areextracted to relieve the permenant incisor crowding. Later the primary first molars and premolars are extracted . To prevent collapse of the mandibular incisors and accentuation of the curve of occulsion, bands are placed on the permanent incisors and first molars and on the primary second molars. Progress is made fromround leveling arches to ideal edgewise arches.

2. Period of interceptive guidance:During this period retention appliances are worn and serial extraction is continued. The parents are informed that appointments will be required every 3 months for assessment of growth and development with the aid of diagnostic records and that teeth will be extracted periodically as indicated.3. Second period of active treatment:When all the permanent teeth have emerged, a multibanded appliance is placed and the Class II is corrected.

Serial extraction in treatment of defferent cases of class II :-A. CASES WITH ANTERIOR DISCREPANCY:MAXILLARY PROTRUSION- Treatment Procedure :1. Extraction of primary maxillary first molars:In this instance the patient has a maxillary alveolodental protrusion with everything else normal. The objective is to retract the maxillary incisor teeth and relieve the anterior discrepancy as early as possible.

To do this, space must be created in the firstpremolar area. To encourage the early eruption of the premolars, the primary first molars are extracted. In the maxilla we can get away with this when the root is nearly one half its length, but not in the mandible. While , if there is mandibular incisor crowding,we must extract the primary mandibular first molars.

(Dugoni, 1992).

2. Extraction of the primary maxillary canines and maxillary first premolars:The primary canines may interfere with the final emergence of the first premolars. This is especially true when a directional force high pull headgear has been utilized to begin the retractionof the maxillary incisors. Therefore , canines should be extracted as well as the premolars. Space is now provided for complete retraction of the maxillary incisors with the high pull headgear.Because there is no lack of space in the mandibular dentition, development is progressing in a normal manner.

3. Extraction of the primary second molars:Treatment time may be accelerated somewhat by extraction of the primary second molars when the second premolars have reached at least one half root length. This step is not always necessary.4. Second period of active treatment:In both the maxillary and the mandibular dentition, when the second premolars begin their emergence and the permanent second molars are about to emerge, the second period ofmultibanded edgewise mechanotherapy is initiated.

5. Retention.

B. CASES WITH MIDDLE DISCREPANCY •IMPACTED MAXILLARY CANINES:- Treatment Procedure :1. Extraction of primary maxillary first molars :The primary first molars are extracted to allow early eruption of the first premolars. This , in turn, creates space for the permanent canines to move away from the roots of the permanent lateral incisors.

2. Extraction of the maxillary first premolars.3. Second period of active treatment:By mechanotherapy.4. Retention.

C. CASES WITH POSTERIOR DISCREPANCY :ECTOPIC ERUPTION IN THE MAXILLA :- Treatment Procedure :1. Extraction of the primary maxillary second molars:A lack of development in the tuberosity area will create the posterior discrepancy that causes the permanent first molars to erupt ectopically in a forward position leading to premature exfoliation or , at least , resorption of the primary maxillary second molars. If the primary molars have not exfoliated, they should be extracted at this time. This will create a Class II relationship of the permanent first molars. The mandibulardentition is relatively normal.

2. Extraction of the primary maxillary first molars:To encourage early emergence of the first premolars, the primary maxillary first molars should be extracted.3. Extraction of the primary maxillary canines if still present and the maxillary first premolars.

4. Multibanded edgewise appliance.

5. Retention.

D. CASES WITH ANTERIOR DISCREPANCY :MAXILLARY PROTRUSION &MANDIBULAR INCISOR CROWDING .-- Treatment Procedure :1. Extraction of the primary maxillary first molars and primary mandibular canines:The purpose of these extractions is to encourage early emergence of the first premolars and to promote favorable alignment of the mandibular incisors. This in aggrement with Dugoni, (1995).

2. Extraction of the primary maxillary canines, maxillary first premolars, and primary mandibular first molars:With extraction of the maxillary first premolars, space has now been provided for retraction of the maxillary incisors by the directional force, high pull, J hook headgear .

3. Extraction of the mandibular first premolars:It is possible that the primary mandibular second molars will have to be extracted to allow for emergence of the first premolars. Then the first premolars are extracted.

4. Second period of active treatment, multibanded edgewise appliance.

5. Retention

E. CASES WITH MIDDLE DISCREPANCY: MAXILLARY AND MANDIBULAR CANINE AND PREMOLAR CROWDING :

- Treatment Procedure :1. Extraction of the primary maxillary first molars:The purpose of this extraction is to encourage eruption of the first premolars and relieve the middle discrepancy. Because of root length development it may not be wise to extract theprimary first molars in the mandible at this time.

2. Extraction of the primary maxillary canines,maxillary first premolars , and primary mandibular first molars.3. Extraction of the primary maxillary second molars and mandibular second premolars :The purpose of extracting the mandibular premolars is to relieve the middle discrepancy and allow for the mesial migration of the permanent first molars.

4. A. Second period of active treatment, multibanded edgewise appliance.5. Retention.

THE TREATMENT OBJECTIVES AFTERSERIAL EXTRACTIONThey are:1. Closure of residual extraction spaces.2. Improvement of the axial inclination of individual teeth.3. Correction of rotations.4. Correction of midline discrepancy.5. Correction of a residual overbite.

6. Correction of a residual overjet.7. Correction of crossbites.8. Refinement of the intercuspation of individual teeth.9. Improvement and coordination of arch form.10. Correction of the Class II relationship in some Class II patients. When the serial extraction phase has been completed, themultibanded appliance is placed and treatment is initiated utilizing the traditional concepts of the orthodontic treatment.

PROPABLE OBSTACLES1. Sometimes removal of premolars does not stimulate the distal migration of canines. In this case, surgical exposure and retraction of canines is indicated.2. Large restorations or caries in second premolars may indicate their extraction instead of first premolars.3. Congenital missing of one or more premolar may create a problem and require a change in the convential serial extraction procedure.4. The removal of premolars in the mandibular arch may enhance the overbite tendency. This will need holding arch or bite-plate.

5. The ultimate status of third molars should be considered. Sometimes extraction of premolars will enhance normal eruption of the third molars.6. The timing of tooth removal: It is not always possible to see the patient at the optimal time for teeth removal.7. It is much difficult to close spaces in the mandibular arch in the premolar area than in the maxillary arch , so, some orthodontists are willing to accept minor irrigularties of the lower incisors and remove only the maxillary firstpremolars.

REFERENCESIngram A.H. "Premolar Enucleation" Angle Orthod. 1976.Joondeph D.R., et al. " Second Premolar Serial Extraction".Am. J. Orthod., 1976.Wagers L.E. " Preorthodontic Guidance And The CorrectiveMixed Dentition Treatment Concept". Am. J. Orthod., 1976.Graber T.M., Swain B.F. " Current Orthodontic ConceptsAnd Techniques". W.B. Saunders Company 1984.Brouwer H. "Child Dental Care And Serial Extraction"British J. Orthod. 1986 Me.Little R.M., et al. "Serial Extraction Of First Premolars -Postretention Evaluation Of Stability And Relapse". AngleOrthod. 199).

Dugoni, S.A. "Mixed Dentition Treatment" Am. J. Orthod. 1992 June.Reading JF. " Dento-Alveolar Disproportion" Aust. Orthod. J., 1993 Mar.Proffit W.R., Fields H.W. "Contenporary Orthodontics“ 1994. (Mosby Year Book).Dugoni , S.A. , "Mixed Dentition Case Report" Am. J. Orthod. 1995 March.Ortial JP. "Vertical Dimension And Therapeutic Choices". Am. J. Orthod. Dentofacial Orthop., 1995 Oct.