MAXILLARY SECOND MOLAR EXTRACTIONS IN ORTHODONTIC TREATMENT

This article is a review of the rationales, indications, methods, andeffects of orthodontic treatment with maxillary second molar extrac-tions. In addition to the patient’s malocclusion, specific considera-tions about the status and position of the maxillary second and thirdmolars should be taken into account. In recent years, the develop-ment of temporary anchorage devices, in addition to extraoral trac-tion and intraoral distalization appliances, has become another arma-mentarium in the distalization of the maxillary posterior teeth, whichmay affect the selection of teeth to be extracted from second to thirdmolars. In conclusion, extraction of maxillary second molars is aviable option in selected cases at present, but it is important tounderstand the indications and limitations of this treatment choice.World J Orthod 2008;9:52–61.

Wilson Lee, BDS, BSc, MOrth,MOrth RCS (Edin)1

Ricky Wing-Kit Wong, BDS,MOrth, PhD, MOrthRCS,FRACDS2

Tomio Ikegami, DDS, CertPedo, Cert Orth, MSc,Dip ABO3

Urban Hägg, DDS, OdontDr, FDSRCS (Edin)4

52

1Advanced Diploma student, Disci-pline of Orthodontics, Faculty ofDentistry, The University of HongKong, Hong Kong SAR, China; pri-vate practice of orthodontics, HongKong SAR, China.

2Associate Professor, Discipline ofOrthodontics, Faculty of Dentistry,The University of Hong Kong, HongKong SAR, China.

3Honorary Clinical Associate Profes-sor, Discipline of Orthodontics, Fac-ulty of Dentistry, The University ofHong Kong, Hong Kong SAR, China;private practice of orthodontics,Kumamoto, Japan.

4Chair and Professor, Discipline ofOrthodontics, Faculty of Dentistry,The University of Hong Kong, HongKong SAR, China.

CORRESPONDENCE Dr Wilson LeeDiscipline of OrthodonticsFaculty of DentistryThe University of Hong Kong2/F, Prince Philip Dental Hospital34 Hospital RoadSai Ying PunHong Kong SAR, China

The maxillary second molars are not acommon choice for extraction in ortho-

dontic treatment. The first comprehen-sive review of the role of maxillary secondmolar extractions in orthodontic treat-ment was published in 1939,1 while themost recent was published in 1996.2

The purpose of this article is to reviewcontemporary views about this treatmentoption. Previously published reports onextraction of the second molars were pri-marily based on the authors’ personalclinical experience rather than evidence-based research.3,4 While most of thereports referred to cases treated with theextraction of all 4 second molars,5–7 only1 report was about extraction of only themaxillary second molars.2 The last com-prehensive review of the literature onextraction of second molars in orthodon-tic treatment was 20 years ago.8

NORMAL DEVELOPMENT OFMAXILLARY SECONDMOLARS

On average, the calcification of the maxil-lary permanent molars commences at2.5 to 3 years of age. The crown is fullyformed at 7 to 8 years, and the tootherupts at 12 to 13 years of age, with itsfinal root formation at 14 to 16 years.9

According to a study by Ling,10 the aver-age mesiodistal crown diameter of themaxillary second molar of a 12-year-oldSouthern Chinese child is 10.3 mm inmales and 10.0 mm in females. In Cau-casians of the same age, it is 10.4 mm inboys and 9.8 mm in girls.11

Lee 2/4/08 3:01 PM Page 52

53

VOLUME 9, NUMBER 1, 2008 Lee et al

RATIONALE FOR MAXILLARYSECOND MOLAR EXTRACTION

The main indication for extraction ofteeth in orthodontic treatment is to cre-ate space. Various rationales for theselection of maxillary second molarextraction are reviewed in the followingsections and summarized in Table 1.

Orthodontic camouflage of ClassII malocclusion

Extraction of maxillary second molarswas once suggested to be indicated forthe correction of Class II division 1 mal-occlusion, provided there was excessivelabial inclination of the maxillary incisorswith no spacing and minimal overbiteand the unerupted maxillary third molarswere in good position and of propershape.12 The diagnostic space-manage-ment guidelines of the Tweed-Merrifieldphilosophy indicated this option in casesof mild skeletal Class II pattern with anANB angle between 5 and 8 degrees.13

This extraction option is also suitable forpatients with a skeletal Class II malocclu-sion, as dentoalveolar compensation, inthose cases for whom bite-jumping is notrecommended because of a prognathicmaxilla and near-correct anterior-poste-rior positioning of the mandible.2,14,15

Patients with Angle Class II division 2malocclusions have retroclined maxillaryincisors and deep overbite. If a protrusive

upper lip and prognathic maxilla are alsopresent, extraction of the maxillary firstpremolars will reduce lip protrusion; how-ever, this option increases the danger ofroot resorption during space closure, dueto the large amount of root torquerequired to move the roots of the maxil-lary incisors into a more palatal posi-tion.16 By extracting the maxillary secondmolars, this problem can be avoidedbecause the orthodontic tooth movementis slow with simultaneous distalization ofall maxillary teeth, allowing bone remod-eling along the maxillary incisor roots totake place. It also allows more efficienttorque control of the maxillary incisors.17

Facial profile

Extraction of the maxillary second molarshas become a popular treatment optionwhen there is concern about the poten-tial adverse effect upon the facial profilewith extraction of the maxillary first pre-molars. Maxillary second molars arelocated in the posterior part of the arch;therefore, the extraction of these teethwill have less effect on the positioning ofthe maxillary incisors during orthodontictreatments than would extraction of themaxillary premolars.18 Thus, extraction ofthe maxillary second molars is indicatedwhen a so-called “dished-in” appearanceof the face at the end of facial growthshould be avoided.15

Table 1 Indications and contraindications of maxillary second molar extraction inorthodontic treatment

Indications

Class II molar and canine relationship with good facial profileDeep overbitePosterior crowding and/or mild anterior crowdingGrossly carious, periodontally involved, or ectopically erupted maxillary second molarsDistally tilted developing maxillary third molarsContraindicationsExcessively protrusive facial profile Agenesis of permanent teethGrossly restored, carious, or periodontally involved maxillary first permanent molars

Lee 2/4/08 3:01 PM Page 53

54

Lee et al WORLD JOURNAL OF ORTHODONTICS

Distalization of the buccal segment

Extractions of the maxillary secondmolars and distalization of maxillary pos-terior teeth may be indicated in patientswith a good facial profile and skeletalClass I pattern but who have Class IImolar and canine relationships, moder-ate maxillary arch crowding, and mildmandibular arch crowding.19 This is par-ticularly true in patients with retroclinedmaxillary and mandibular incisors. Theextraction of the maxillary second molarsprovides the space required for align-ment of the teeth and for attaining cor-rect occlusal relationships, as well asfacilitating the distal movement of themaxillary posterior teeth.

In cases of severe posterior crowdingin the maxillary arch, extraction of themaxillary second molars may also beindicated. In some complex cases, it maybecome necessary to extract the maxil-lary first premolars, as well.

I f the developing maxil lary thirdmolars encounter a lack of space foreruption, the space created after extrac-tion of the maxillary second molars canprovide space not only for the distaliza-tion of the posterior teeth, but also forthe eruption of the maxillary third molars.Research has shown that, in general, themaxillary third molars will erupt favorablyin such cases.20 Simple extraction of themaxillary second molars may preventpossible trauma arising from the surgicalremoval of eventually impacted maxillarythird molars.

A sample case is presented in Figs 1to 3 to demonstrate the successful man-agement of severe Angle Class II division1 malocclusion, with extraction of maxil-lary second molars combined with head-gear treatment and fixed appliances.

Fig 1 Treatment sequence of a female, 12 years 9 months of age, with an Angle Class II division 1 malocclusion. (a) Pretreat-ment. (b) After 6 months of cervical headgear. (c) After 2 years of headgear treatment. Note that the axial inclination of themaxillary incisors was corrected as the posterior teeth were distalized. (d) Fixed appliance, worn for 3 months. (e) Finishingstage with the multiloop edgewise archwire technique. (f) Posttreatment.

a b c

d e f

Lee 2/4/08 3:01 PM Page 54

55

VOLUME 9, NUMBER 1, 2008 Lee et al

Fig 2 Lateral profiles, frontal profiles, and overjet: (a to c) Pretreatment. (d to f) Posttreatment. (g to i) Ten years posttreatment.

a b c

d e f

g h i

Lee 2/4/08 3:01 PM Page 55

56

Lee et al WORLD JOURNAL OF ORTHODONTICS

Condition of the maxillary secondmolars

When the maxillary second molars aregrossly carious, periodontally compro-mised, or ectopically erupted,21 theirextraction can also be considered as atreatment option.

CONTRAINDICATIONS

Agenesis, or severe mesioangulation, ofthe maxillary third molars is a contraindi-cation of orthodontic treatment withextraction of the maxillary second molars(see Table 1). The general pattern of max-illary third molar eruption is downward

Fig 3 Panoramic radiographs. (a) Pretreatment. (b) Nine months after headgear treatment. (c) Sixteen months after headgeartreatment. (d) Three years after the start of headgear treatment. (e) Posttreatment. Note the positioning of the maxillary thirdmolars. (f) Retention (3 years 9 months posttreatment).

a b

c d

fe

Lee 2/4/08 3:01 PM Page 56

and forward21; an ideal maxillary thirdmolar will have a slight distoangular posi-tion that will allow it to rotate mesially asit descends into the occlusion.

Orthodontic treatment with maxillarysecond molar extraction requires distal-ization of the maxillary first molars, whichmay result in some bite opening; there-fore, it may be contraindicated in patientswith open bite. Patients with a maxillaryprotrusive facial profile would likely bene-fit more from extraction of the maxillaryfirst premolars, since conventional distal-ization would eventually result in posteriorrotation of the mandible, thus increasingthe lower facial height and worsening thefacial appearance. The use of the newtemporary anchorage devices (TADs)seems to have the potential to reducethese adverse effects by providing verticalcontrol.

ADVANTAGES

From the literature, the following reasonsare proposed as the major advantages ofmaxillary second molar removal: (1) noexcessive retrusion of the maxillary ante-rior teeth and normalization of maxillaryincisor inclination during retraction, com-pared to maxillary first premolar extrac-tion, and hence less adverse change ofprofile in cases of mild Class II malocclu-sion with mild crowding22; (2) better sta-bility of treatment results23,24; (3) avoid-ance of maxillary molar staggering andimpaction22; (4) facilitation of maxillaryfirst molar distal movement15; (5) distalmovement of the maxillary dentition only,as needed to correct the overjet and max-illary crowding; (6) no trauma of maxillarythird molar extraction22; and (7) preser-vation of more the patient’s completedentit ion, from right molars to lef tmolars, compared with extraction of allfirst premolars.

It has been demonstrated that theextraction of maxillary second permanentmolars can be effective in many caseswhere removal of maxillary first or sec-ond premolars would otherwise be recommended.25

DISADVANTAGES

The following are disadvantages of themaxillary molar extraction treatmentoption: (1) too much tooth substanceremoved in Class I malocclusions withmild crowding15,24; (2) extraction sitesare far from the area of concern in mod-erate-to-severe anterior crowding15; (3)extraction sites are of no help in the cor-rection of anteroposterior discrepancieswithout patient cooperation in wearingextraoral appliances capable of movingthe dentition “en masse” distally; (4)potentially insufficient size and form ofthese molars24; and (5) unpredictablepath of eruption of maxil lary thirdmolar.26

OPTIMAL TIMING FOR EXTRACTIONS

Ideally, maxillary second molars shouldbe extracted when the maxillary thirdmolars reach the vertical midline of themaxillary second molar root in a Class Imalocclusion.27 In a Class II malocclu-sion, because treatment often needs dis-talization of the maxillary first molars, themaxillary third molars should be approxi-mately at the level of the cementoenameljunction of the maxillary second molarsat the time of extraction.27 The maxillarythird molars should be developed to theirbifurcation before extraction of the maxil-lary second molars.9

CHANGES IN MAXILLARYTHIRD MOLAR POSITION

With proper diagnosis and careful treat-ment planning, most maxillary thirdmolars would erupt successfully intogood position.25,27 After extraction of themaxillary second molars, the maxillarythird molars rotate and tip mesially withdescent; the greater the original distalangulation, the greater the amount ofrotation.20

Recent research has shown that max-illary third molars uprighted and accept-ably replaced maxillary second molarsafter extraction for orthodontic purposes

57

VOLUME 9, NUMBER 1, 2008 Lee et al

Lee 2/4/08 3:01 PM Page 57

58

Lee et al WORLD JOURNAL OF ORTHODONTICS

in 95% of such-treated cases.27 Unsuc-cessful eruption of the maxillary thirdmolars has been shown to be due toprior excessive mesial tilting or lack ofproximal contact.27

The eruption prognosis of the maxil-lary third molars improves when theyhave a favorable inclination, with a 15- to30-degree angle distal to the long axis ofthe maxillary first molars.21,23 The mesialsurface of the unerupted maxillary thirdmolars should be “fairly in line horizontallywith the distal surface of the mandibularsecond molars.”21

With proper selection of cases, theform and size of the erupted maxillarythird molars after orthodontic treatmentwith extraction of the maxillary secondmolars was acceptable nearly 90% of thetime; all maxillary third molars eruptedwith mesial contact, and in 90% of thecases, the maxillary third molars hadacceptable axial inclination and positionwithout the need for further alignment.2

Bennett and McLaughlin28 concludedthat the pantomographic evaluation ofthe changes in third-molar angulationbefore and after orthodontic treatmentwith extraction of all second molars werenot statistically different. In both groups,the maxillary third molars showed animprovement in angulation, while themandibular third molars showed anundesirable increase in angulation. Arecent study by De-la-Rosa-Gay et al27

reported similar results.

EFFECTS OF ORTHODONTICTREATMENT WITH EXTRACTION

Few studies have investigated the effectsof extraction of maxillary second molarsin orthodontic treatment. These studieshad different treatment objectives andthe characteristics of the samples weredifferent.2,6,29

One of the objectives of extractingmaxillary second molars is to minimizethe change in patient profile after ortho-dontic treatment. Basdra et al2 did a pre-and posttreatment cephalometric analy-sis of 32 young patients (mean age of14.6 years) with Class II malocclusion

who had extraction of maxillary secondmolars. Primarily angular measurementswere used in the cephalometric analysis;however, the l inear measurementsshowed that both upper lips and maxil-lary incisors were significantly retracted.This study did not include any controlgroup.

Staggers6 examined treatment resultsof maxillary and mandibular secondmolar extraction cases and comparedthem with treatment results of maxillaryand mandibular first premolar extractioncases. The results showed that the 2groups had fewer differences than oftenindicated by advocates of second molarextraction. However, the maxillary andmandibular incisors and the lower lip inthe premolar extraction group wereretracted significantly more than those inthe maxillary second molar group. Theresulting facial profile after extraction ofsecond molars appears to have no signifi-cant difference from that obtained afterextraction of first premolars. However,this comparison would only be valid if theamount and site of crowding were similarin both groups, factors that were notmentioned in the study.28 The averagetreatment time did not differ statisticallybetween the groups.

Waters and Harris29 conducted a retro-spective cephalometric study to comparethe nature of the skeletodental correctionof maxillary second molar extraction andnonextraction treatments in correctingClass II malocclusions. The sample com-prised Class II, deep-bite, low-angle ado-lescents; half were treated with maxillarysecond molar extraction and half weretreated without extraction. Pitchforkanalysis30,31 was used to evaluate sagit-tal changes (in mm) of the teeth and sup-porting bones, relative to the functionalocclusal plane. There was no significantdifference in the dentofacial morphologybetween the 2 groups at the start oftreatment. Several skeletodental treat-ment changes dif fered significantlybetween the 2 groups. The maxillary sec-ond molar extraction group exhibited dis-tal movement of the maxil lary f irstmolars (1.2 mm vs 0.0 mm), and therewas greater flaring of the mandibularincisors in the nonextraction group (9.1

Lee 2/4/08 3:01 PM Page 58

59

VOLUME 9, NUMBER 1, 2008 Lee et al

degrees vs 3.5 degrees). The maxillaryincisor roots were torqued lingually inboth groups, but there was more anteriorcrown movement in the nonextractiongroup (2.0 mm vs 0.0 mm). Sagittalmolar correction in the maxillary secondmolar group was a result of distalizing ofthe maxillary first molars to correct themalocclusion in the nonextraction group.On average, the extraction group finishedactive treatment 7 months earlier thanthe nonextraction group. It was con-cluded that in properly selected Class IImalocclusions, extraction of maxillarysecond molars is a viable alternativetreatment choice.

EXTRACTION IN CONJUNCTIONWITH FIXED APPLIANCETHERAPY

Rix32,33 showed that sometimes theextractions of 4 premolars provided morespace than was actually needed in ClassII division 1 malocclusions with borderlinecrowding of the mandibular incisors. As aresult, he recommended the extraction of4 second molars in conjunction withmonobloc therapy as a better alternative.

In a study on extraction of maxillaryand mandibular second molars in 78patients with Class II malocclusions, 21patients had no orthodontic treatment, 9patients were treated with activators withsprings to move the first molars distally,and 48 had fixed appliances.34 It wasstated that the advantages of thismethod of treatment included ease indistally moving mandibular first molars ifthey were mesially tipped, the rapid andcomplete eruption of the third molars,and complete space closure of theextraction sites. The limitation of thisapproach is the assumption of the pres-ence and proper eruption of the thirdmolars. Moreover, moving mandibularfirst molars distally can be mechanicallydifficult and, in Class II cases, there isthe need to move all the anterior andposterior permanent teeth distally for thecorrection of overjet.

Sfondrini et al35 did a comprehensiveanalysis of the effect of maxillary molardistalization with various appliances.

They mentioned that distalization of max-illary posterior teeth with the extractionof maxillary second molars will reducethe treatment duration compared tononextraction treatment. Various types ofdistalization appliances were discussed,including headgears, acrylic cervicaloccipital, transpalatal arch, Wilson bimet-ric distalizer, Herbst, Jasper jumper, andpendulum. It was concluded that ifpatient compliance was good andanchorage demand was maximum, theuse of extraoral traction for distalizationof the maxillary first molars was the besttreatment option. However, the use ofTADs for maxillary distalization of molarswas not mentioned.

At present, there are no scientificallyviable data available to compare thelong-term results of similar malocclusionscorrected with maxillary premolar vs maxillary second molar extractions.

EXTRACTION IN CONJUNCTIONWITH TADS

Temporary anchorage devices havebecome increasingly popular in orthodon-tic treatment. There have been recentstudies discussing the effects of TADs indistalization of maxillary posterior teethwith or without the extraction of maxillarysecond or third molars.36–40 A study bySugawara et al38 reported that the aver-age amount of distalization of the maxil-lary first molars was 3.8 mm at the crownlevel and 3.2 mm at the root level. Kyunget al39 reported the use of a midpalatalmicroscrew together with a transpalatalarch to distal ize the maxil lary f irstmolars, illustrated with 2 case reports. Inthese 2 young patients, the maxillarymolars moved distally 5 mm from thecrowns and 3.5 mm from the apiceswithin 3 to 5 months, without the extrac-tion of second molars.

Gelgor et al41 investigated the efficiencyof intraosseous screws for anchorage inmaxillary molar distalization and the sagit-tal and vertical skeletal, dental, and softtissue changes after maxillary molar distal-ization using intraosseous screw-sup-ported anchorage. An anchorage unit wasprepared for molar distalization by placing

Lee 2/4/08 3:01 PM Page 59

an intraosseous screw behind the incisivecanal at a safe distance from the mid-palatal suture, following the palatalanatomy. The screws were placed andimmediately loaded to distalize the maxil-lary first molars; the maxillary secondmolars were present. The average distal-ization time to achieve an overcorrectedClass I molar relationship was 4.6months. The skeletal and dental changeswere measured on cephalograms anddental casts obtained before and afterthe distalization. Analysis of the lateralcephalograms showed that, on average,the maxillary first molars were tipped 8.8degrees and moved 3.9 mm distally. Mea-surements of the dental casts showed a mean distalization of 5.0 mm. The max-illary first molars were rotated disto-palatally. On average, mild protrusion(mean 0.5 mm) of the maxillary centralincisors was also recorded. However,there was no change in overjet, overbite,or mandibular plane angle measure-ments. It was concluded that the immedi-ately loaded intraosseous screw-sup-ported anchorage unit was successful inachieving sufficient maxillary molar distal-ization without major anchorage loss.

CONCLUSIONS

This review discussed a number of issuesrelated to maxillary second molar extrac-tions, including the indications, con-traindications, advantages, disadvan-tages, optimal timing for extraction, aswell as how it affects the eruption of max-illary third molars. The reviewed literaturestrongly suggests that in carefullyselected cases, the extraction of maxillarysecond molars relieves crowding in the

posterior part of the arch and facilitateseruption of maxillary third molars (Table 2).

It is important to consider the biologi-cal and mechanical requirements andconsequences of a particular treatmentplan for both short- and long-term results,as well as the effects of these decisionson the duration of treatment, facial pro-file, periodontal tissues, and functionalocclusion. To determine the possibleadvantages of maxillary second molarextraction versus other extraction andnonextraction concepts, there is a needfor randomized clinical trials that evalu-ate and compare both short- and long-term treatment outcomes.

REFERENCES

1. Chapin WC. The extraction of maxillary secondmolars to reduce growth stimulation. AmOrthod Oral Surg 1939;11:1072–1078.

2. Basdra EK, Stellzig A, Komposch G. Extractionof maxillary second molars in the treatment ofClass II malocclusion. Angle Orthod 1996;66:287–292.

3. Harnick DJ. Case report: Class II correctionusing a modified Wilson bimetric distalizingarch and maxillary second molar extraction.Angle Orthod 1998;68:275–280.

4. Dickson JA, Jones AG. Extraction of four secondpermanent molars in the presence of severepremolar crowding: A case report. Dent Update1996;23:339–340, 342-333.

5. Smith R. The effects of extracting upper sec-ond permanent molars on lower second perma-nent molar position. Br J Orthod 1996;23:109–114.

6. Staggers JA. A comparison of results of secondmolar and first premolar extraction treatment.Am J Orthod Dentofacial Orthop 1990;98:430–436.

7. Wilson HE. Angle’s Class II, Division 2. DentPract 1964;14:245–255.

8. Bishara SE, Ortho D, Burkey PS. Second molarextractions: A review. Am J Orthod 1986;89:415–424.

60

Lee et al WORLD JOURNAL OF ORTHODONTICS

Table 2 Summary of effects expected after maxillary second molar extraction in orthodontic treatment

Effect

Extraoral Increase in upper lip–to–E-line; more palatal root torque but less anterior crown movementthan in nonextraction group

Vertical No reported change in vertical relationshipDental Ninety-six percent of maxillary third molars will erupt into good positionTransverse No change

Lee 2/4/08 3:01 PM Page 60

61

VOLUME 9, NUMBER 1, 2008 Lee et al

9. Mitchell L, Carter NE, Doubleday B. An Intro-duction to Orthodontics. Oxford: Oxford Univer-sity Press, 2001.

10. Ling J. A Morphometric Study of the Dentitionof 12 year old Chinese Children in Hong Kong.Hong Kong: University of Hong Kong, 1992.

11. Moorrees CFA. The Dentition of the GrowingChild: A Longitudinal Study of Dental Develop-ment Between 3 and 18 Years of Age. Cam-bridge: Harvard University Press, 1959.

12. Graber TM. The role of upper second molarextraction in orthodontic treatment. Am JOrthod 1955;41:354.

13. Graber TM, Swain BF. Orthodontics: CurrentPrinciples and Techniques. St Louis: Mosby,1985.

14. Rees H, Witt E. Second molar extractions. Zahnarztl Prax 1981;32:222–237.

15. Basdra EK, Komposch G. Maxillary secondmolar extraction treatment. J Clin Orthod1994;28:476–481.

16. Wong RWK, Rabie ABM, Bendeus MSA. Ortho-dontic management of Class II Division 2 mal-occlusion using 2 by 3 appliance and molardistalization. Hong Kong Dental AssociationLimited-Millenium Report 2001;II:12–15.

17. Litt RA, Nielsen IL. Class II, division 2 malocclu-sion. To extract—or not extract? Angle Orthod1984;54:123–138.

18. Halderson H. Early permanent second molarextractions in orthodontics. J Can Dent Assoc1959;25:549–560.

19. Wong AM, Rabie AB, Hagg U. The use of pendu-lum appliance in the treatment of Class II mal-occlusion. Br Dent J 1999;187:367–370.

20. De-la-Rosa-Gay C, Valmaseda-Castellon E, Gay-Escoda C. Spontaneous third-molar eruptionafter second-molar extraction in orthodonticpatients. Am J Orthod Dentofacial Orthop2006;129:337–344.

21. Chipman M. Second and third molars: Theirrole in orthodontic therapy. Am J Orthod 1961;47:498–520.

22. Haas AJ. Let’s take a rational look at perma-nent second molar extraction. Am J OrthodDentofacial Orthop 1986;90:361–363.

23. Lehman R. A consideration of the advantagesof second molar extractions in orthodontics.Eur J Orthod 1979;1:119–124.

24. Stellzig A, Basdra EK, Komposch G. Skeletaland dentoalveolar changes after extraction ofthe second molars in the upper jaw. J OrofacOrthop 1996;57:288–297.

25. Quinn GW. Extraction of four second molars.Angle Orthod 1985;55:58–69.

26. Brown ID. The unpredictable lower third molar.A case report. Br Dent J 1974;136:155–156.

27. Magness WB. Extraction of second molars. JClin Orthod 1986;20:519–522.

28. Bennett JC, McLaughlin RP. Orthodontic Man-agement of the Dentition with the PreadjustedAppliance. London: Mosby, 2001.

29. Waters D, Harris EF. Cephalometric comparisonof maxillary second molar extraction andnonextraction treatments in patients with ClassII malocclusions. Am J Orthod DentofacialOrthop 2001;120:608–613; quiz 677.

30. Johnston LE Jr. Balancing the books on ortho-dontic treatment: An integrated analysis ofchange. Br J Orthod 1996;23:93–102.

31. Johnston LE Jr. An objective evaluation of thepitchfork analysis (PFA). Eur J Orthod2002;24:121–122; author reply 122–123.

32. Rix R. Some problems for consideration. II.Trans Br Soc Orthod 1960:108–117.

33. Rix R. Further thoughts on monobloc therapy.Trans Br Soc Orthod 1966:1–12.

34. Rindler A. Second permanent molar extractionin Class II cases with crowding in the lowerarch. Sven Tandlak Tidskr 1970;63:699–708.

35. Sfondrini MF, Cacciafesta V, Sfondrini G. Uppermolar distalization: A critical analysis. OrthodCraniofac Res 2002;5:114–126.

36. Carano A, Velo S, Incorvati C, Poggio P. Clinicalapplications of the mini-screw-anchorage-system (M.A.S.) in the maxillary alveolar bone.Prog Orthod 2004;5:212–235.

37. Sugawara J, Daimaruya T, Umemori M, et al. Distal movement of mandibular molars in adultpatients with the skeletal anchorage system.Am J Orthod Dentofacial Orthop 2004;125:130–138.

38. Sugawara J, Kanzaki R, Takahashi I, NagasakaH, Nanda R. Distal movement of maxillarymolars in nongrowing patients with the skeletalanchorage system. Am J Orthod DentofacialOrthop 2006;129:723–733.

39. Kyung SH, Hong SG, Park YC. Distalization ofmaxillary molars with a midpalatal miniscrew. JClin Orthod 2003;37:22–26.

40. Lee JS, Kim DH, Park YC, Kyung SH, Kim TK.The efficient use of midpalatal miniscrewimplants. Angle Orthod 2004;74:711–714.

41. Gelgor IE, Buyukyilmaz T, Karaman AI, DolanmazD, Kalayci A. Intraosseous screw-supportedupper molar distalization. Angle Orthod 2004;74:838–850.

Lee 2/4/08 3:01 PM Page 61