Congenitally Missing Mandibular CE - Spear Aesthetics · the lingual. This factor requires that the...

C ongenital absence of mandibularsecond premolars affects many or-

thodontic patients. The clinician mustmake the proper decision at the appro-priate time regarding management ofthe edentulous space.1 If space will beleft open for an eventual restoration, thekeys during orthodontic treatment areto create the correct amount of spaceand leave the alveolar ridge in an idealcondition to receive a restoration in thefuture. In the distant past, either con-ventional bridges or, more recently,resin-bonded bridges have been usedto fill in the edentulous space. However,full-coverage conventional bridges inyoung patients can result in devitaliza-tion of the pulp and require root canaltherapy.2 Resin-bonded posterior bridg-es have a questionable survival rate.3-5

Today, the first choice of restoration fora congenitally missing mandibular pre-molar should be a single-tooth implant.6

But if the implant cannot be placeduntil the patient has completed facialgrowth, how should the edentulous ridgebe preserved?

Ostler and Kokich7 evaluated thelong-term changes in the width of thealveolar ridge after extraction of man-dibular primary second molars. Theirdata showed that the ridge narrows by25% during the first 4 years after pri-mary tooth extraction. After 7 years,the ridge narrows another 5%, for atotal reduction of 30% over 7 years.However, these authors showed thatthese ridges were still broad enough toreceive a dental implant. Unfortunately,the ridge resorbs more on the facial thanthe lingual and, therefore, although theimplant can be placed without a bonegraft, the implant position is more tothe lingual. This factor requires that therestorative dentist alter the loading ofthe buccal and lingual cusps of the crownon the implant to avoid fracture of theabutment or the implant crown.8

Another option is to maintain theprimary tooth until the patient is oldenough to place the implant. The appro-priate age for implant placement is de-termined by the cessation of vertical facialgrowth. That parameter is determined

Congenitally Missing MandibularSecond Premolars: Clinical Options

Learning Objectives

After reading this article, the readershould be able to:

• discuss treatment options fororthodontic patients who havecongenital absence of mandib-ular second premolars.

• describe the criteria that shouldbe considered in creating atreatment plan using a single-tooth implant.

• understand how the anatomy ofyoung orthodontic patientscan affect treatment outcomes.

Vincent G. Kokich, DDS, MSDProfessor, Department of Orthodontics

School of DentistryUniversity of Washington

Seattle, Washington

Vincent O. Kokich, DMD, MSDAffiliate Assistant Professor

Department of OrthodonticsSchool of Dentistry

University of WashingtonSeattle, Washington

Abstract:Background: Congenital absence of mandibular second premolars affects many orthodontic patients.The orthodontist must make the proper decision at the appropriate time regarding management of theedentulous space. These spaces may be closed or left open.

Implications: If space will be left open for an eventual restoration, the keys during orthodontic treat-ment are to create the correct amount of space and leave the alveolar ridge in an ideal condition to receivea restoration in the future. If space will be closed, the clinician must avoid altering the occlusion andfacial profile in a way that would be detrimental to the patient.

Significance: Some of the decisions that the orthodontist makes early on in the life of a patient who iscongenitally missing mandibular second premolars will affect these patients and their dental health fora lifetime. Therefore, the correct decision must be made at the appropriate time.

Purpose: This article will present and discuss a variety of treatment alternatives for managing the ortho-dontic patient who is congenitally missing one or both mandibular second premolars.

CE

2 ADVANCED ESTHETICS & INTERDISCIPLINARY DENTISTRY JUNE 2007—VOLUME 3, NUMBER 2

Reprinted with permission from American Journal of Orthodontics & Dentofacial Orthopedics. 130:437-444.©2006 American Association of Orthodontics.

AEID_V3N2_CE_5th 5/10/07 4:54 PM Page 2

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by comparing serial cephalometric radio-graphs to determine when ramus growthand, therefore, vertical changes in fa-cial growth have stopped. Fudalej andcoworkers9 have shown that, on av-erage, females continue facial growthuntil about 17 years of age, while theaverage male completes facial verticalgrowth at about 21 years of age. There-fore, maintaining the primary toothuntil the cessation of growth is desir-able. But primary molars are too widemesiodistally, which could affect the fitof the posterior teeth. So, it is advan-tageous to reduce the width of the pri-mary second molar to the size of asecond premolar.1

The reduction of a primary molarshould be accomplished with a sharpcarbide fissure bur or a diamond bur.The key is to remove sufficient toothstructure to create space, but not enoughto cause pulpal necrosis. A guide to es-timating the correct amount of reduc-tion is to measure the mesiodistal widthof the primary molar at the level of thecementoenamel junction on a bitewing

radiograph (Figure 1). This distance canbe transferred to and marked on theocclusal surface of the primary molar us-ing a pencil or marking pen. Then, thebur is positioned to follow this lineand cut down toward the gingival to re-move a wafer of enamel and underly-ing dentin on both the mesial anddistal surfaces (Figure 1). About 2 mmmay be removed from both mesial anddistal surfaces, which should leave thecrown about 7 mm to 8 mm wide.

A potential problem of reducing theprimary molar in this way is that it leavesexposed dentin on the mesial and distalsurfaces of the tooth. As the spaces areclosed, it would be difficult for thepatient to adequately clean these inter-proximal surfaces, and the tooth coulddecay easily. Therefore, in order to pre-vent decay, a layer of light-cured re-storative composite should be appliedto the mesial and distal surfaces to pro-tect the primary tooth. In addition toprotecting these exposed dentinal sur-faces, the addition of restorative com-posite will build up the occlusal surface

JUNE 2007—VOLUME 3, NUMBER 2 ADVANCED ESTHETICS & INTERDISCIPLINARY DENTISTRY 3

Figure 1 This adolescent female was congenitally missing her mandibular right permanent second premolar and the primary second molar was present andsubmerged below the level of the occlusal plane (A). The radiograph showed that the root had not resorbed (B). Since the bone levels were flat betweenthe primary and adjacent permanent teeth, the tooth was maintained. The tooth was too wide (C), so the mesial and distal surfaces were reduced sub-stantially (D,E). The tooth was built up with composite (F,G) in order to reduce the caries risk. The pulp was not damaged (G) after the space was closed (H)and the posterior teeth were brought into occlusion (H,I).

A B C

D E F

G H I

...have shown that, onaverage, females continuefacial growth until about

17 years of age, whilethe average male completesfacial vertical growth atabout 21 years of age.

Therefore, maintainingthe primary tooth

until the cessation ofgrowth is desirable.

AEID_V3N2_CE_4th 5/10/07 9:04 AM Page 3

of the typically short primary molar, soit can function with the teeth in the op-posing dental arch and prevent super-eruption. After composite restoration,the interproximal spaces can be closed,and the primary molar now functions asa premolar (Figure 1).

A common concern about closingthese interproximal spaces after reduc-tion of the primary tooth is that the rootsof the primary teeth will prevent com-plete space closure, because these rootstend to diverge beyond the width of thecrown. However, in most cases, as thesocket wall of the permanent teeth movenear and into contact with the primarytooth roots, the latter will resorb. Afterresorption, these primary roots are re-placed with bone, which is an ideal wayto prepare this site for a future implant.1

Occasionally a primary second molarmay become ankylosed. If the ankylosisoccurs while the patient is young andstill undergoing significant facial growth,then the tooth will become submergedrelative to the adjacent erupting perma-nent teeth.1 If this region will be restored

with an implant in the future, then thealveolar ridge could be compromisedvertically and require a bone graft.10

However, vertical bone grafting is oftenunpredictable11 and an added expensefor the patient. Therefore, extraction ofankylosed primary molars is recommend-ed if the patient is missing the primarysecond molar and still has significantfacial growth remaining. But how doesthe clinician diagnose ankylosis in thechild or adolescent? The most reliableindicator of primary molar ankylosis isto evaluate the alveolar bone levels be-tween the primary molar and the adja-cent permanent first molar and firstpremolar.1 If the bone is flat, this indi-cates that the primary tooth and theadjacent teeth are erupting evenly. How-ever, if the alveolar bone level becomesoblique, with the bone level located moreapically around the primary tooth, thisconfirms ankylosis (Figure 2). If thepatient has little facial growth remain-ing, and the primary molar is only sub-merged slightly, the tooth can be main-tained in order to preserve the width of

the alveolus for the future implant.However, if the patient has significantgrowth remaining, the primary molarmust be extracted to avoid producing asignificant ridge defect.

A common question after primarymolar extraction is whether or not toplace a space maintainer to preserve thearch length. Personally, we do not placespace maintainers in most of thesesituations, especially if implants will bethe choice of restoring the edentulousspace. If the edentulous space is notmaintained, the adjacent permanent firstmolar and first premolar should erupttogether (Figure 2). Although this couldrequire longer orthodontic treatmentto push the teeth apart to create the im-plant space, this type of tooth movementwill also result in a more robust alveo-lar ridge (Figure 2). As the roots of adja-cent teeth move away from one another,they deposit bone behind that equalsthe width of the premolar and molar andwill produce an excellent ridge in whichto place the implant. This process is calledorthodontic implant site development.


Figure 2 This female child was missing her mandibular right and left permanent second premolars, and the primary first and second molars were anky-losed and submerged (A,B). All primary molars were extracted and the permanent first premolar and first molar drifted toward one another and closed thespace (C,D). Since the mandibular incisors were positioned lingually relative to the chin (E), the treatment plan involved opening of the second premolarspace (F), followed by placement of an implant (G), and porcelain crown (H). This treatment plan resulted in an ideal Angle Class I occlusion after ortho-dontic treatment (I).

A B C

D E F

G H I



Occasionally the decision to extractan ankylosed and submerged primarysecond molar will be made too late, re-sulting in a narrow alveolar ridge with avertical defect. If an implant will beplaced in this site, a bone graft may benecessary to provide adequate ridge widthand height. However, another possibilityexists, especially if the patient will beundergoing orthodontic therapy. It maybe advantageous to push the first pre-molar into the second premolar position,thereby creating space for the single-tooth implant in the first premolarlocation. When faced with this deci-sion, clinicians are often fearful that thereis insufficient alveolar ridge width inwhich to move the permanent first pre-molar. However, previous studies12,13

have shown that a wider tooth root canbe pushed through a narrow alveolarridge without compromising the even-tual bone support around the reposi-tioned tooth root. We have performedthis type of tooth movement on severaloccasions resulting in a much better ridgein which to place the implant.

Another possible situation is the pa-tient who is missing not only the sec-ond premolar, but also the first perma-nent molar (Figure 3). If some driftingof the adjacent teeth has occurred, theresulting edentulous space may be toolarge for one-tooth replacement, andtoo small for two-teeth replacement. Inthese situations, it could be advantage-ous to place a single-tooth implant inthe appropriate position prior to theorthodontic treatment. This implantcan be restored and used as an anchorto close any excess and remaining space,using the implant as an anchor to avoidunwanted occlusal changes in the re-maining dentition.14 The advantage tothe patient is a reduction in the num-ber of restorations required to fill theedentulous space. The advantage to theorthodontist is having an immobile an-chor in the bone to protract or retractthe adjacent teeth to close the space.This type of interdisciplinary treatmentrequires proper planning, the construc-tion of a diagnostic wax-up, and precisepositioning of the implant to satisfy the

Figure 3 This adult female was missing the mandibular right second premolar and permanent first molar (A). As a result, there was too much space for one-tooth replacement and too little space for two-teeth replacement (B,C). An implant was placed in the first premolar position (D). It was restored (E) and abracket was placed on the implant provisional crown (F). The implant was used to close the remaining edentulous spaced (G). The width of the final pre-molar crown was normal size (H) and an Angle Class I occlusion was achieved (I).

A B C

D E F

G H I

...If some drifting ofthe adjacent teeth hasoccurred, the resulting

edentulous space may betoo large for one-toothreplacement, and toosmall for two-teeth

replacement. In thesesituations, it could beadvantageous to placea single-tooth implant

in the appropriateposition prior to the

orthodontic treatment.



Figure 4 This adolescent female had an end-to-end malocclusion (A) and was congenitally missing three second premolars (B). Her facial profile was ideal.In order to avoid any future restorations and prevent any negative facial changes, a chin cup and elastics were used to protract the maxillary and mandibu-lar molars into a class I relationship (D). This significant tooth movement eliminated the need for extensive restorative dentistry (E), without jeopardizingher facial profile (F).

A B C

D E F

orthodontic, surgical, and restorative ob-jectives (Figure 3).

If an implant is used to move adjacentteeth and close an edentulous space, thetiming of implant loading is an impor-tant factor. In the past, implant loadingtraditionally has been delayed until theimplant had fully integrated with the sur-rounding bone.15 However, recent stud-ies have shown that early or immediateloading is possible,16,17 especially in theorthodontic patient.18 The differenceis that an orthodontic load is continuousand in one direction, whereas an occlusalload is intermittent and in differentdirections. Researchers have shown thata continuous load in the same directionactually stimulates bone formation,which further enhances the osseointe-gration of the implant. So, in most ortho-dontic situations, implants may be loadedearly, soon after the restorative dentisthas placed the temporary restoration.

Another alternative for treating thepatient who is congenitally missing themandibular second premolars is to sim-ply close the space.19 If the patient hascrowding in the opposite dental arch,or a protrusive facial profile, closure of theedentulous space would be advantage-ous. However, in the patient with no den-tal crowding and a normal facial profile,closure of the edentulous space from acongenitally missing second premolarcould produce an undesirable facial pro-file. In these situations, the orthodontist

requires additional anchorage, either ex-traoral or intraoral, to avoid these un-wanted facial changes. A protractionfacemask or a chin cup (Figure 4) aretwo examples of extraoral appliances thatwill accomplish this type of tooth move-ment. Miniscrews20 and mini-implantsare an intraoral method of providing ad-ditional anchorage to close these edentu-lous spaces without altering the patient’sfacial profile. Another method of clos-ing the edentulous space is to hemisect theprimary second molar at an early age,21,22

and allow the permanent molar to eruptin a mesial direction without affectingthe position of the mandibular inci-sors. If the orthodontist can see the pa-tient at an early age and monitor thepatient on a regular basis, this alterna-tive is especially attractive.

Case Presentation 1This 12-year, 4-month-old female

was congenitally missing the mandibu-lar right second premolar. The right pri-mary second molar was present, butwas submerged below the occlusal lev-els of the adjacent teeth (Figure 1A). Theradiograph of the primary tooth showsthat the bone levels between the primarymolar and the adjacent permanent teethare flat (Figure 1B). This indicates thatthe primary tooth was not ankylosed andhad erupted evenly with the adjacentteeth. The mesiodistal width of the pri-mary molar was 13 mm (Figure 1C),

in the patient with nodental crowding and a

normal facial profile, closureof the edentulous space

from a congenitally missingsecond premolar couldproduce an undesirableacial profile. In these

ituations, the orthodontistrequires additional

anchorage, either extraoralor intraoral, to avoid theseunwanted facial changes.



Figure 5 This late adolescent female was congenitally missing her mandibular left second premolar and the primary molar was ankylosed and submerged(A). The primary molar was extracted, which resulted in a significant narrowing of the edentulous ridge (B). The first premolar was pushed distally (C,D,E)into the second premolar position. This orthodontic movement allowed an implant to be placed in the newly regenerated bone (F,G). After restoration ofthe first premolar implant in the second premolar position (H), it is difficult to recognize any difference (I).

A B C

D E F

G H I

while the normal width of an averagemandibular second premolar is 7.5mm. Although a single-tooth implantwas the planned replacement for themissing premolar, the patient was tooyoung and still growing. In order topreserve the buccolingual bone for aneventual implant, the primary molarwas reduced in width (Figure 1D andFigure 1E), restored with composite (Fig-ure 1F and Figure 1G), and the remain-ing space was closed in order to produceclass I molar and canine relationshipsafter orthodontic therapy (Figure 1Hand Figure 1I).

Case Presentation 2This young girl was 8 years, 3 months

of age and had bilateral, submerged man-dibular primary second molars (Figure2A). The radiograph (Figure 2B) showedthat the bone levels between the rightprimary second molar and adjacentpermanent first molar were angled oroblique, indicating that the permanenttooth had continued to erupt. All re-maining primary teeth were extracted,

no space maintaining appliances wereplaced, and the remaining permanentteeth were allowed to erupt (Figure 2C).Even though a significant vertical bonydefect remained immediately after ex-traction of the submerged primary molar,subsequent tooth eruption normal level(Figure 2D) and eliminated the alveo-lar defect. Since the position of themandibular incisors was located so far tothe lingual (Figure 2E), the mandibularincisors were proclined labially, and spacewas opened between the premolar andmolar (Figure 2F) for the placementof a single-tooth implant (Figure 2G).This implant was restored with a secondpremolar crown (Figure 2H), whichhelped to re-establish proper occlusionfor the patient. The bone to house theimplant was created through orthodon-tic implant site-development.

Case Presentation 3This adult female was missing her

mandibular right second premolar andfirst molar. The mandibular second mo-lar was in an Angle Class II relationship

with the maxillary first molar (Figure3A), and the edentulous space betweenthe second molar and first premolar(Figure 3B), was too large for one toothand too small for two teeth. After ini-tial orthodontic alignment (Figure 3C),a diagnostic wax-up was constructed todetermine the precise position for a sec-ond premolar implant (Figure 3D). Afterintegration of the implant, a provisionalcrown was attached (Figure 3E), and abracket was placed on the implant-sup-ported crown (Figure 3F). The implantwas used as an anchor to move the man-dibular right second molar mesially intoan Angle Class I relationship, withoutjeopardizing orthodontic anchorage,the position of the remaining anteriorteeth (Figure 3G), or the patient’s facialprofile. The final porcelain crown onthe implant (Figure 3H) was the appro-priate size, and the eventual posttreatmentocclusion was finished in an ideal AngleClass I relationship (Figure 3I). Usingthe implant as an anchor for partial clo-sure of a two-tooth space minimized the


complexity of the orthodontics and therestorative management of this patient.

Case Presentation 4This 13-year, 8-month-old patient

had an Angle Class II occlusion bilat-erally, with a 5-mm anterior overjet (Fig-ure 4A). She had a minor arch lengthdeficiency in both arches, but was con-genitally missing the maxillary right,and mandibular right and left perma-nent second premolars (Figure 4B). Hermaxilla and mandible were well related(Figure 4C), and the maxillary and man-dibular incisors were in a relatively nor-mal anteroposterior position. Extractionof the maxillary left second premolarand remaining primary second molarsand closure of all edentulous spaces wouldhave been detrimental to her facialprofile by overly retracting the lips rel-ative to the chin. The only options foravoiding the incisor retraction wouldhave been placement of mini-implantsfor anchorage to protract the maxillaryand mandibular first molars, or extra-oral anchorage to achieve the same ob-jective. Since this patient was treatedprior to the era of mini-implants, a chin-cup and elastics were used to slide themaxillary and mandibular first molarsmesially along a continuous archwire.The posttreatment dental casts (Figure4D) show that an Angle Class I molarrelationship was achieved. The intrao-ral radiograph (Figure 4E) shows theamount of tooth movement that oc-curred, and the cephalometric super-imposition before and after orthodontics(Figure 4F) provides verification thatthe mandibular incisors did not movelingually, but that the mandibular mo-lars moved entirely mesially using theprotraction force. Although this toothmovement required 4 years of ortho-dontic treatment, the patient has norestorations, and the facial profile hasbeen maintained in spite of the threecongenitally missing premolars.

Case Presentation 5This 14-year, 6-month-old female

was congenitally missing her mandibu-lar left second premolar (Figure 5A), andthe primary second molar was anky-losed and submerged. The maxillaryleft second premolar was present butdelayed in its eruption. After extraction

of the primary second molar, substan-tial bone resorption with significantvertical and buccolingual narrowing ofthe alveolar ridge had occurred (Figure5B). This degree of ridge defect wouldprobably narrow even further and re-quire a bone graft prior to implant re-placement. However, another approachinvolved moving the first premolar intothe second premolar position (Figure5C through Figure 5E), which createdadequate ridge for the first premolarimplant. When the flap was elevated toplace the implant, sufficient alveolarbone was located distal to the premo-lar where the ridge had been deficient(Figure 5F). By using the adjacent toothas the stimulus for alveolar site devel-opment, no bone graft was necessary,when the implant was placed (Figure5G). The final crown on the mandibu-lar implant provides the proper spaceand support for the occlusion, and thefirst premolar functions nicely in thesecond premolar position.

SummaryThis article has described and illus-

trated several methods of managing thepatient who is congenitally missing man-dibular second premolars. In the past,orthodontists primarily made the treat-ment decisions in these types of patients.However, with the addition of newersolutions to restoring edentulous spaces,surgeons and restorative dentists mayplay a significant role in helping to man-age these types of orthodontic patients.Although the orthodontist may see thesepatients at a young age, some of the de-cisions that are made at that time willaffect the patient for a lifetime. This arti-cle has emphasized the interdisciplinaryaspects of treating a patient who is con-genitally missing their mandibular sec-ond premolars, in order to provide thepatient with the best possible result thatteamwork dentistry can offer.

References1. Spear F, Mathews D, Kokich V. Interdisciplin-

ary management of single-tooth implants.Semin Orthod. 1997;3:45-72.

2. Habsha E. The incidence of pulpal complica-tions and loss of vitality subsequent to fullcrown restorations. Ont Dent. 1998;75:19-21.

3. Ketabi A, Kaus T, Herdach F. Thirteen-yearfollow-up study of resin-bonded fixed par-tial dentures. Quintessence Int. 2004;35:407-410.

4. Zalkind M, Ever-Hadani P, Hochman N. Resin-bonded fixed partial denture retention: Aretrospective 13-year follow-up. J Oral Re-habil. 2003;30:971-977.

5. Creugers N, De Kanter R, Verzijden C, Van’tHof M. Risk factors and multiple failures inposterior resin-bonded bridges in a 5-yearmulti-practice clinical trial. J Dent. 1998;26:397-402.

6. ADA Council on Scientific Affairs. Dental En-dosseous implants: An update. J Am DentAssoc. 2004;135:92-97.

7. Ostler M, Kokich V. Alveolar ridge changes inpatients congenitally missing mandibular sec-ond molars. J Prosthet Dent. 1994;71:144-149.

8. Kokich V, Spear F. Guidelines for managingthe orthodontic-restorative patient. SeminOrthod. 1997;3:3-20.

9. Fudalej P, Kokich V, Leroux B. Determiningthe cessation of facial growth to facilitate place-ment of single-tooth implants. Am J OrthodDentofac Orthop. In press.

10. Chen S, Darby I, Adams G, Reynolds E. A pro-spective clinical study of bone augmentationtechniques at immediate implants. Clin OralImplants Res. 2005;16:176-184.

11. Jemt T, Lekholm U. Single implants and buc-cal bone grafts in the anterior maxilla: Meas-urements of buccal crestal contours in a 6-yearprospective clinical study. Clin Implant DentRelat Res. 2005;7:127-135.

12. Stepovich M. A clinical study on closing eden-tulous spaces in the mandible. Angle Orthod.1979;49:227-233.

13. Hom B, Turley P. The effects of space closureof the mandibular first molar area in adults.Am J Orthod. 1984;85:457-469.

14. Kokich V. Comprehensive management ofimplant anchorage in the multidisciplinarypatient. In: Orthodontic Applications of Osseo-integrated Implants. Higuchi K, ed. Quintes-sence. 2000;21-32.

15. Adell R, Lekholm U, Rockler B. A 15-year studyof osseointegrated implants in the treatmentof the edentulous jaw. Int J Oral Surg. 1981;10:387-416.

16. Tarnow D, Emtiaz S, Classi A. Immediate load-ing of threaded implants at stage 1 surgeryin edentulous arches: ten consecutive casereports with 1- to 5- year data. Int J Oral Max-illofac Implants. 1997;12:319-324.

17. Piattelli A, Corigliano M, Scarano A. Imme-diate loading of titanium plasma-sprayedimplants: an histologic analysis in monkeys.J Periodontol. 1998;69:321-327.

18. Duyck J, Ronold H, Van Oosterwyck H. Theinfluence of static and dynamic loading onmarginal bone reactions around osseoin-tegrated implants: An animal experimentalstudy. Clin Oral Implants Res. 2001;12:207-218.

19. Fines C, Rebellato J, Saiar M. Congenitally mis-sing mandibular second premolar: Treatmentoutcome with orthodontic space closure. Am JOrthod Dentofacial Orthop. 2003;123:676-682.

20. Giancotti A, Greco M, Mampieri G. The useof titanium miniscrews for molar protractionin extraction treatment. Prog Orthod. 2004;5:236-247.

21. Northway W. Hemisection: One large steptoward management of congenitally missinglower second premolars. Angle Orthod. 2004;74:792-799.

22. Northway W. The nuts and bolts of hemisec-tion treatment: Managing congenitally missingmandibular second premolars. Am J OrthodDentofacial Orthop. 2005;127:606-610.



Continuing Education QuizTufts University School of Dental Medicine provides 1 hour of Continuing Education credit for this article for those who wishto document their continuing education efforts. To participate in this CE lesson, please log on to www.AEID.AEGISCE.net,where you may further review this lesson and test online for a fee of $14.00. To obtain mailing instructions or for moreinformation, please call 877-4-AEGIS-1.

1. If space will be left open for an eventualrestoration, the keys during orthodontictreatment are to:a. create the correct amount of space.b. leave the alveolar ridge in an ideal condition to

receive a restoration in the future.c. straighten the remaining teeth until an implant

can be placed.d. a and b

2. Which of the following can result indevitalization of the pulp in young patients?a. root canal therapyb. full-coverage conventional bridgesc. amalgam restorationsd. conventional orthodontics

3. Ostler and Kokich evaluated the long-termchanges in the width of the alveolar ridge afterextraction of the mandibular primary secondmolars. Their data showed that the ridge:a. widens by 20% during the first 3 years after

primary tooth extraction.b. narrows by 20% during the first 3 years after

primary tooth extraction.c. widens by 25% during the first 4 years after

primary tooth extraction.d. narrows by 25% during the first 4 years after

primary tooth extraction.

4. After 7 years, the ridge:a. widens by another 5%.b. narrows by another 5%.c. widens by another 10%.d. narrows by another 5%.

5. The appropriate age for implant placementis determined by the cessation of:a. primary tooth eruption.b. vertical facial growth.c. horizontal facial growth.d. secondary tooth eruption.

6. Fudalej and coworkers have shown that,on average, females continue facial growthuntil about:a. 16 years of age.b. 17 years of age.c. 18 years of age.d. 19 years of age.

7. The same researchers have shown that,on average, males continue facial growthuntil about:a. 18 years of age.b. 19 years of age.c. 20 years of age.d. 21 years of age.

8. Primary molars are too wide:a. mesiodistally.b. mesioocclusally.c. distalocclusally.d. distal-lingually.

9. A guide to estimating the correct amount ofreduction is to measure the mesiodistal widthof the primary molar at the level of the:a. adjacent teeth.b. cementoenamel junction.c. the gingiva.d. crown of the root.

10. The most reliable indicator of primary molarankylosis is to evaluate the alveolar bone levelsbetween the:a. secondary molar and adjacent molar and first

premolar.b. crown of the molar and the gingiva.c. primary molar and the adjacent permanent

first molar and first premolar.d. primary molar and the adjacent canine.

Tufts University School of Dental Medicine

is an ADA CERP and ACDErecognized provider.

Association for ContinuingDental Education

JUNE 2007—VOLUME 3, NUMBER 2 ADVANCED ESTHETICS & INTERDISCIPLINARY DENTISTRY 17


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