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Introduction

The effects of a lip bumper on the mandibulardentition are well documented The use of theappliance results in an appreciable widening of

the dental arch at the canines and premolars(Cetlin and Ten Hoeve 1983 Nevant et al 1991Osborn et al 1991 Werner et al 1994 Grossenand Ingervall 1995) and a slight proclination of the incisors (Nevant et al 1991 Osborn et al1991 Werner et al 1994 Grossen and Ingervall1995) The distalizing effect on the first molarshas in some studies been found to be small andtherefore the increase in arch length (a result of

incisor proclination and molar distalization) tobe only moderate (Nevant et al 1991 Osbornet al 1991 Werner et al 1994 Grossen andIngervall 1995) In one study (Nevant et al1991) more distal movement and distal tippingof the molar crown was found in patients wear-ing a lip bumper with a vestibular shield than insubjects having had only a lip bumper of roundwire covered with plastic tubing This was in linewith the results of Bjerregaard et al (1980) whoreported considerable distal molar tipping fromthe use of a lip bumper with a vestibular shield

In a recent study by OrsquoDonnell et al (1998)where a wire lip bumper was tied in for 1 year theeffect on the molar was intermediate betweenthat usually found with a wire lip bumper (Nevantet al 1991 Osborn et al 1991 Grossen and

Ingervall 1995) and that produced by a shield lipbumper (Bjerregaard et al 1980 Nevant et al1991) When a wire lip bumper was used in themixed dentition the first molars in most casesmoved mesially into the leeway space (Werneret al 1994)

Most of the studies of the effect of a lower lipbumper indicate that the increase in arch perim-eter may be attributed to an increase in arch

width rather than in arch length (Nevant et al1991 Osborn et al 1991 Werner et al 1994Grossen and Ingervall 1995) In a recent studyby Davidovitch et al (1997) however wheretomography was used to record molar movementand angulation more effect on the molar fromthe lip bumper was noted compared with thatfound with conventional cephalometry The useof tomography has the advantage of allowinganalysis of the right and left sides separately incontrast to the inevitable superimposition withconventional cephalometry

European Journal of Orthodontics 22 (2000) 25ndash32 983209 2000 European Orthodontic Society

The effect of a maxillary lip bumper on tooth positions

Rudolf Haumlsler and Bengt IngervallDepartment of Orthodontics University of Bern Switzerland

SUMMARY The effect of the use of a lip bumper with anterior vestibular shields on the maxillawas studied in twenty-two 9ndash14-year-old children with a space deficiency in the maxillarydental arch The lip bumper was used for 1 year

The effect of the treatment was evaluated from dental casts and profile cephalograms madebefore and after treatment Both the width of the maxillary dental arch at the premolars andthe length of the arch increased significantly by about 2 mm The effect of the treatment onthe antero-posterior position of the first molars was small In one subject the molar wasdistalized 28 mm The average effect was however a reduction in the anterior movementof the molar within the face by about 05 mm ie the maxilla moved anteriorly 1 mm butthe molar only 04 mm No skeletal effects were found when the group of subjects treatedwith a lip bumper was compared with a reference sample of untreated individuals Themain effects of a maxillary lip bumper thus seem to be a widening of the dental arch acrossthe premolars a moderate increase in arch length due to eruption and slight proclination

of the incisors and moderate distal tipping of the first molars



While the picture of the effect of a lip bumper

on the mandibular dentition is relatively clearnothing is known about the effects of such anappliance when used in the maxilla A lip bumperin the maxilla could be a good alternative forincreasing the arch perimeter in the interceptivetreatment of subjects with a Class III tendencyIn such cases with a retrognathic and small maxillathere is often an obvious space deficiencyExtraction of maxillary teeth is an unfavourable

solution because it exaggerates the discrepancyin size between the maxillary and mandibulardental arches The possibilities of proclining theincisors or transversally expanding the dental archare limited for reasons of stability Distalizationof the molars would be a possible way to gainspace but cannot be carried out with headgearbecause of the risk of increasing the maxillaryretrognathism through the orthopaedic effect

This risk would be less with a lip bumper whichsimultaneously to the holding or distalization of the molars could bring about a slight proclinationof the incisors and a transverse development of the dental arch

The present study was undertaken in order toevaluate the effects of a lip bumper on themaxillary dentition

Subjects and methods

Seven boys and 15 girls participated in the studyTheir ages varied between 9 years 3 monthsand 13 years 7 months (median age 10 years6 months) The children were treated with a lipbumper in the maxilla for 10ndash14 months (median12 months) In addition to the lip bumper nineof the children also had a Goshgarian transpalatal

arch (TPA) anchored to the first permanentmolars Five children wore the TPA throughoutthe period of treatment with the lip bumper andthe remaining four children for 15ndash9 monthsof this period No other appliance was used inthe maxilla during this period

The children were treated at the Departmentof Orthodontics University of Bern The lipbumper was inserted in an attempt to gain spacein the maxilla A headgear for distalization ofthe maxillary molars in order to gain space wascontra-indicated in these children because of

their Class III or tendency to Class III skeletalintermaxillary relation

The type of lip bumper used is shown inFigure 1 It was made of 11-mm stainless steeland had custom-made acrylic shields in the labialfold opposite the anterior teeth (on each side inthe region between the canine and the central

incisor) The shield covered the gingiva 2ndash3 mmabove the gingival margin and reached 6ndash7 mmocclusal to the gingival margin The lip bumperwas anchored in buccal tubes on the maxillaryfirst permanent molars and was adjusted to lie2ndash3 mm away from the labial surfaces of theincisors and canines and from the buccal surfacesof the premolars The children were instructedto wear their lip bumper day and night and to

remove it only for meals or for tooth brushingControl visits were scheduled every secondmonth at which time the position of the lipbumper was checked and adjusted if necessaryThe lip bumper was used passively ie it was notadjusted for active expansion

The effects of the lip bumper were docu-mented by measurements on dental casts andprofile cephalograms made immediately before

and after treatment The recording on the castincluded measurement of the width of themaxillary dental arch at the first permanentmolars premolars and canines The measuringpoints are shown in Figure 2 When the premolarsor permanent canines were not erupted thecorresponding points on the deciduous teethwere used No measurement was made when adeciduous tooth was replaced by its successorduring the period of observation The length of the dental arch was measured from a lineconnecting the tip of the mesiobuccal cusp of the

26 R HAumlSLER AND B INGERVALL

Figure 1 Type of lip bumper used for the treatment



right and left first molars to the mid-point of theincisal edge of the two central incisors The meanof the measurement to the right and left incisorwas used as the variable for arch length Allmeasurements were made with electronic dialcalipers to the next tenth of a millimetre The

results of the measurements of the dental archdimensions were compared with the annualchanges of the same dimensions in the untreatedgroup of Moyers et al (1976) For this comparisontheir sample was matched with the present indi-viduals with regard to sex and age This matchingwas undertaken separately for each variable

The reference points and lines used in thecephalometric analysis are shown in Figure 3

The point m was located on the distal surface of the first molar band Before radiography a metal

rod was inserted in the buccal tubes of the rightand left first permanent molar bands respect-ively The length of the straight metal rod whichextended vertically gingivally and occlusallymesial to the mesial opening of the buccal tubeswas 15 mm The metal rod was used to measure

the inclination of the first molars in relation toOLP The design of the rod on the right andleft sides was different so that a differentiationcould be made In the cephalometric analysis thechange in position of point m as well as in theinclination of the molar on the two sides wasaveraged The dimensions measured on thecephalograms were reduced to zero magnifica-tion The changes of the distances ssndashpm prndashpm

and isndashpm as well as of the angle ILsNL in thetreated group were compared with the annualchanges of the same variables in the untreatedsample of Bahtia and Leighton (1993) Theirsample was matched with the present individualswith regard to sex and age This was carriedout individually for each variable Analysis of antero-posterior linear changes was performedwith the method of Pancherz (1982) A co-

ordinate system consisting of the occlusal line(OL) and a perpendicular to this line throughthe point sella (OLP) was drawn on a tracing of the pre-treatment cephalogram The co-ordinatesystem was transferred to the post-treatmentcephalogram by superimposing on structures of the anterior cranial base as described by Bjoumlrk(1968) All variables recorded on the casts orcephalograms were measured twice with newmarkings on the casts or new tracings Themean of the two measurements was used in theanalysis

EFFECT OF A MAXILLARY LIP BUMPER 27

Figure 2 Measuring points used in the recording of the dental arch dimensions The figure also shows the median changesin widths and arch length during the period of observation

Figure 3 Reference points and lines used in the measure-ments on the cephalograms



Errors of the method and statistical

methods used

The errors of the method were calculated fromthe duplicate measurements made before andafter treatment Systematic differences betweenthe duplicate measurements were tested withWilcoxonrsquos matched pairs signed ranks test Theaccidental errors of the method ( s

i) were calcu-

lated with the formula

si = radicΣd22n

where d is the difference between two measure-ments and n the number of recordings

Differences between distributions were testedwith MannndashWhitneyrsquos U -test and between pairedobservations with Wilcoxonrsquos matched pairssigned ranks test

The number of duplicate determinations of the

variables measured on the casts varied between18 and 44 No systematic differences were foundfor these variables The accidental errors variedfrom 016 to 041 mm The number of duplicatedeterminations of the cephalometric variableswas 36 One systematic difference was foundThe angle ILsNL was on average 040 degreeslarger at the second than at the first measure-ment (001 lt P lt 005) The accidental errors for

the measurement of distances on the cephalo-grams varied between 020 and 031 mm Theerrors for the measurement of the molar inclin-ation and for the angle ILsNL were 071 and081 degrees respectively Because the analysis

of the results of the treatment was based onreplicated measurements the errors were reducedby a factor of 07

Results

The changes of the dimensions of the maxillarydental arch during treatment are given in Table 1The variation in number of observations in Table 1and in Figure 4 is due to the fact that the widths

at the premolarsdeciduous molars and at thecanines could not be measured in all subjectsdue to the varying stage of development of thedentition There was no difference in the changesbetween cases having and not having had a TPAduring treatment Therefore no differentiationwith regard to the use of a TPA was made Thechange in width between the first permanentmolars during the treatment varied widely from

a decrease of 2 mm to an increase of 75 mm Themedian change during treatment was small andnot significant and nor was any significantdifference found in relation to the referencesample The widths between the secondpremolars or the second deciduous molars aswell as between the first premolars increasedsignificantly during treatment and developedsignificantly differently to the corresponding

dimensions in the reference sample The changein width in the individual cases treated with thelip bumper is shown in Figure 4 All subjects of the treatment group had an increase of thedimensions mentioned The widths between


Table 1 Median and range (in mm) of changes in the dimensions of the maxillary dental arch duringtreatment The table also gives the median annual changes in the matched reference sample (Moyers et al1976) The varying number of observations is due to varying development of the dentition

Width between n Median Range Median in Significance of differencereference sample in test-reference

First molars 22 03 ndash20ndash75 05 NSSecond premolars 6 22 01ndash46 ndash01 Second deciduous molars 7 15 02ndash33 02 First premolars 11 22 06ndash47 ndash01 First deciduous molars 3 09 08ndash10 0 NSCanines 6 08 ndash06ndash17 ndash03 NS

Deciduous canines 3 11 09ndash26 0 NSArch length 22 19 01ndash40 ndash03

001 lt P lt 005 0001 lt P lt 001 P lt 0001 NS non-significant



the first deciduous molars and between thecanines also showed a numerical increase butthe number of observations was too small toallow statistical analysis The length of the dentalarch increased significantly during treatment andalso when compared with the reference sampleAll subjects showed an increase in arch length(Figure 5) For the reference sample in contrastthe arch length decreased in 20 cases (up to07 mm)

The changes of the variables measured on theprofile cephalogram are given in Table 2 Therewas no significant difference in the change of first molar position between patients who had orhad not worn a TPA Therefore no differenti-ation of the sample with regard to the use of aTPA was undertaken During the period of treatment the maxilla (point ss) and the maxillaryincisors (point is) moved anteriorly by 10 and

15 mm (median) respectively Only one patientshowed a distal movement of the maxilla orincisors The anterior movement of the molarswas less and not significant The movement of the molars varied from an anterior movement of 15 mm to a posterior movement of 28 mm Thenext largest posterior movements were 14 and065 mm The crowns of the first molars tippedposteriorly by 58 degrees (median) The molars

tipped anteriorly in only one caseThe maxilla increased in length (distances

ssndashpm prndashpm isndashpm) by 10ndash13 mm (median) andthe incisors proclined 14 degrees The proclinationof the incisors was however not significant andnone of these changes were significant comparedwith the changes in the reference material


Figure 4 Change in width in the individual cases betweenthe second premolars (a) between the second deciduousmolars (b) and between the first premolars (c) during thetreatment

Figure 5 Change in arch length in the individual cases during treatment



Discussion

For this study a lip bumper with vestibularshields was chosen The force from the lip on abumper with shields has in the mandible beenfound to be greater than on a wire lip bumper(Hodge et al 1997) and this may also be assumedto be true for the maxilla The difference in forceis thought to be due to the larger surface area of

contact between the lip and the appliance whenshields are used The upper lip is much weakerthan the lower The mean pressure at rest fromthe lower lip on the lower incisors amounts to9ndash12 gcm2 against 2ndash5 gcm2 from the upper lipon the upper incisors (Thuumler et al 1985 Thuumlerand Ingervall 1986 1990) Therefore a bumperwith shields is necessary if the distally-directedforce from the lip bumper on the molars is to be

of any appreciable magnitudeThe changes of most of the variables during

the period of treatment were compared with thechanges of the same dimensions in samples of children followed for the study of normal growthand development These samples (Moyers et al1976 Bahtia and Leighton 1993) comprise chil-dren with normal occlusion and varying types of malocclusions It cannot be taken for granted thatthe changes with growth and development of thesechildren are quite comparable with those of thechildren of the present study who had a Class

III or a tendency to Class III intermaxillaryskeletal relationship Furthermore the childrenof the reference samples were from differentpopulations than those of this investigation Thedata in the reference samples were collectedseveral decades ago It is therefore possible thatsecular changes may influence a comparison withthe present results A control group of childrenwith the same characteristics as the group of

treated children would have been preferable forthe comparison The collection of such materialwas however impossible for ethical reasonsand also because of the scarcity of children withClass III morphology When comparing thetreated children and the reference samples thelimitations mentioned should be kept in mind

The median increase in width between thefirst permanent molars during treatment was

negligible This may be due to the fact that the lipbumper was used passively ie a change in widthbetween the first molars was hindered by therigid lip bumper and that in many cases theinter-molar width was controlled by a TPAIn one subject however the width between thefirst molars was purposely expanded 75 mm Inthe premolar area on the other hand there wasa considerable widening of the dental archwhich was significant when compared with thereference sample There was also an increase ininter-canine width which however was not


Table 2 Median and range (in mm and degrees) of changes in antero-posterior position of points ss is andm as well as dimensions of the maxilla and inclination of the maxillary central incisors and maxillary molars

during treatment The table also gives the median annual changes in maxillary dimensions and in theinclination of the incisors in the matched reference sample (Bahtia and Leighton 1993) n = 18

Median Range Median in Significance of differencereference sample in test-reference

Antero-posterior position of pointsss 10 ndash03ndash18is 15 ndash17ndash38m 04 ndash28ndash15

Inclination of first molars(degree) ndash58 ndash182ndash38

Distance ssndashpm 10 ndash03ndash34 08 NSDistance prndashpm 12 ndash03ndash36 10 NSDistance isndashpm 13 ndash03ndash40 11 NSILsNL (degree) 14 ndash28ndash77 ndash01 NS

A positive sign means anterior movement or change in inclination in an anterior direction NS not significant0001 gt P gt 001



significant The number of inter-canine widthobservations was however small The increase inmaxillary inter-premolar widths achieved by thelip bumper treatment was much the same asthe increase in mandibular inter-premolarwidths achieved by the use of a lower lipbumper (Osborn et al 1991 Nevant et al 1991Werner et al 1994 Grossen and Ingervall 1995Davidovitch et al 1997 OrsquoDonnell et al 1998)

In contrast to the situation in the mandible

there is possibly more than one explanation forthe increase in arch width from a lip bumperused in the maxilla One explanation whichwould hold true for both the maxilla and themandible is that the lip bumper changes the oralenvironment by holding the lips and cheeksaway from the dental arches thus altering theequilibrium between the forces from the cir-cumoral soft tissues and from the tongue acting

on the teeth The effect of the lip bumper wouldthen be similar to that of the vestibular shields of a Fraumlnkel appliance (Fraumlnkel 1974) The otherexplanation is that a maxillary lip bumperincreases the growth in the mid-palatal sutureThis has been shown to be the case with the useof vestibular shields in growing rabbits (Kalogirouet al 1996) In that animal experiment howeverthe shields were extended to create tension in

the buccinator insertions The authors suggestedthat the increased sutural growth was due torelief of the buccal pressure and continuedtongue pressure against the dento-alveolar boneleading to separation of the adjoining bone andsutural growth as a passive filling process In thepresent study the increase in width between thefirst molars as well as between the second pre-molarssecond deciduous molars and between the

first premolarsfirst deciduous molars and be-tween the canines was the same in subjects withand without a TPA during treatment A TPAholds the two maxillary halves together therebydecreasing the possibility of mid-palatal suturalgrowth expressing itself Therefore the explan-ation for the increase in maxillary dental archwidth produced by the lip bumper treatment ismost likely the change in equilibrium of theforces acting on the surfaces of the teeth

The growth in length of the maxilla was notaffected by the lip bumper treatment as the

distance ssndashpm increased similarly in the treatedgroup and the reference sample The same is truefor the distances prndashpm and isndashpm In relation tothe reference line OLP the maxilla (point ss) inthe treated group moved 1 mm (median)anteriorly during the period of observationUnfortunately the literature contains no suchmeasurement for untreated samples The mediananterior movement of is was 15 mm iesomewhat more than for point ss This may

be due to eruption of the incisor andor to aslight increase in its inclination which changedmore in the treated group than in the referencesample The anterior movement of the first molar(point m) was only half that of the maxilla (pointss) and signifies a slight holding effect (medianabout half a millimetre) from the lip bumper onthe molar In single cases the molars may movedistally but this rarely exceeds 1 mm The small

effect of the lip bumper on the molars in termsof holding or distalization may be due to thesmall force produced by the upper lip but asmentioned in the introduction in many studiesa similar small effect was also found in themandible In a previous study of the effect of alip bumper in the mandible (Grossen andIngervall 1995) the state of development anderuption of the second molars was found not to

influence the effect of the bumper on the firstmolars A similar analysis could not be carriedout in the present study because we refrainedfrom taking additional radiograms and becauseone or both second molars were only erupted infour cases as judged from the dental casts

The increase in arch length from molar holdingdistalization and from incisor eruptionproclinationwas limited and quite comparable with that found

with the use of a lip bumper in the mandible(Osborn et al 1991 Grossen and Ingervall 1995Davidovitch et al 1997 OrsquoDonnell et al 1998)The main effect of a maxillary lip bumper seemsto be a widening of the dental arch across thepremolars This is of course beneficial but it isnot the ultimate solution to the space deficiencyproblem in a retrognathic maxilla On the otherhand no negative effects of the use of a maxil-lary lip bumper were found

It is an open question whether the expansiveeffect of a lip bumper and the proclination of the




incisors are stable in the long term The results of Soo and Moore (1991) indicated an adaptation of the lower lip to the tooth position achieved withlower lip bumper treatment In their study thepressure from the lower lip both at rest and duringspeech first increased (at 1 month) but then (at8 months) decreased below baseline These obser-vations are at variance with the results of recentstudies OrsquoDonnell et al (1998) found no decreaseof the pressure from a lower lip bumper on the

first molars after one year of uninterrupted useIngervall and Thuumler (1998) found the pressurefrom the lower lip on the lower incisors to be thesame after 8 months of lower lip bumper treat-ment as at the start The lip had not adapted tothe changed position of the incisors nor had itreacted to the extension by the lip bumper There-fore the conclusion of Houston and Edler (1990)may be correct namely lsquowith a few exceptions

the initial position of the lower incisors providesthe best guide to their position of stabilityrsquo

Address for correspondence

Professor Bengt IngervallKlinik fuumlr KieferorthopaumldieFreiburgstrasse 7CH-3010 Bern Switzerland

References

Bahtia S N Leighton B C 1993 A manual of facial growthOxford University Press Oxford

Bjerregard J Bundgaard A M Melsen B 1980 The effect of themandibular lip bumper and maxillary bite plate on toothmovement occlusion and space conditions in the lowerdental arch European Journal of Orthodontics 2 257ndash265

Bjoumlrk A 1968 The use of metallic implants in the study of

facial growth in children method and application AmericanJournal of Physical Anthropology 29 243ndash254

Cetlin N M Ten Hoeve A 1983 Nonextraction treatmentJournal of Clinical Orthodontics 17 396ndash413

Davidovitch M McInnis D Lindauer S J 1997 The effects of lipbumper therapy in the mixed dentition American Journalof Orthodontics and Dentofacial Orthopedics 111 52ndash58

Fraumlnkel R 1974 Decrowding during eruption under thescreening influence of vestibular shields American Journalof Orthodontics 65 372ndash406

Grossen J Ingervall B 1995 The effect of a lip bumper onlower dental arch dimensions and tooth positions Euro-pean Journal of Orthodontics 17 129ndash134

Hodge J J Nanda R S Ghosh J Smith D 1997 Forces pro-duced by lip bumpers on mandibular molars American

Journal of Orthodontics and Dentofacial Orthopedics111 613ndash622

Houston W J B Edler R 1990 Long-term stability of thelower labial segment relative to the AndashPog line Euro-pean Journal of Orthodontics 12 302ndash310

Ingervall B Thuumler U 1998 No effect of lip bumper therapyon the pressure from the lower lip on the lower incisorsEuropean Journal of Orthodontics 20 525ndash534

Kalogirou K Ahlgren J Klinge B 1996 Effects of buccal

shields on the maxillary dentoalveolar structures and themidpalatal suturemdashhistologic and biometric studies inrabbits American Journal of Orthodontics and Dento-facial Orthopedics 109 521ndash530

Moyers R E van der Linden F Riolo M McNamara J Jr1976 Standards of human occlusal development Mono-graph No 5 Craniofacial Growth Series Center for HumanGrowth and Development University of Michigan AnnArbor Michigan

Nevant C T Buschang P H Alexander R G Steffen J M1991 Lip bumper therapy for gaining arch lengthAmerican Journal of Orthodontics and DentofacialOrthopedics 100 330ndash336

OrsquoDonnell S Nanda R S Ghosh J 1998 Perioral forces anddental changes resulting from mandibular lip bumpertreatment American Journal of Orthodontics andDentofacial Orthopedics 113 247ndash255

Osborn W S Nanda R S Currier G F 1991 Mandibular archperimeter changes with lip bumper treatment American

Journal of Orthodontics and Dentofacial Orthopedics 99527ndash532

Pancherz H 1982 The mechanism of Class II correctionin Herbst appliance treatment A cephalometric investi-gation American Journal of Orthodontics 82 104ndash113

Soo N D Moore R N 1991 A technique for measurement of intraoral lip pressures with lip bumper therapy AmericanJournal of Orthodontics and Dentofacial Orthopedics 99409ndash417

Thuumler U Ingervall B 1986 Pressure from the lips on theteeth and malocclusion American Journal of Ortho-dontics and Dentofacial Orthopedics 90 234ndash242

Thuumler U Ingervall B 1990 Effect of muscle exercise withan oral screen on lip function European Journal of Orthodontics 12 198ndash208

Thuumler U Janson T Ingervall B 1985 Application in childrenof a new method for the measurement of forces from thelips on the teeth European Journal of Orthodontics 763ndash78

Werner S P Shivapuja P K Harris E F 1994 Skeletodentalchanges in the adolescent accruing from use of the lipbumper Angle Orthodontist 64 13ndash22




While the picture of the effect of a lip bumper

on the mandibular dentition is relatively clearnothing is known about the effects of such anappliance when used in the maxilla A lip bumperin the maxilla could be a good alternative forincreasing the arch perimeter in the interceptivetreatment of subjects with a Class III tendencyIn such cases with a retrognathic and small maxillathere is often an obvious space deficiencyExtraction of maxillary teeth is an unfavourable

solution because it exaggerates the discrepancyin size between the maxillary and mandibulardental arches The possibilities of proclining theincisors or transversally expanding the dental archare limited for reasons of stability Distalizationof the molars would be a possible way to gainspace but cannot be carried out with headgearbecause of the risk of increasing the maxillaryretrognathism through the orthopaedic effect

This risk would be less with a lip bumper whichsimultaneously to the holding or distalization of the molars could bring about a slight proclinationof the incisors and a transverse development of the dental arch

The present study was undertaken in order toevaluate the effects of a lip bumper on themaxillary dentition

Subjects and methods

Seven boys and 15 girls participated in the studyTheir ages varied between 9 years 3 monthsand 13 years 7 months (median age 10 years6 months) The children were treated with a lipbumper in the maxilla for 10ndash14 months (median12 months) In addition to the lip bumper nineof the children also had a Goshgarian transpalatal

arch (TPA) anchored to the first permanentmolars Five children wore the TPA throughoutthe period of treatment with the lip bumper andthe remaining four children for 15ndash9 monthsof this period No other appliance was used inthe maxilla during this period

The children were treated at the Departmentof Orthodontics University of Bern The lipbumper was inserted in an attempt to gain spacein the maxilla A headgear for distalization ofthe maxillary molars in order to gain space wascontra-indicated in these children because of

their Class III or tendency to Class III skeletalintermaxillary relation

The type of lip bumper used is shown inFigure 1 It was made of 11-mm stainless steeland had custom-made acrylic shields in the labialfold opposite the anterior teeth (on each side inthe region between the canine and the central

incisor) The shield covered the gingiva 2ndash3 mmabove the gingival margin and reached 6ndash7 mmocclusal to the gingival margin The lip bumperwas anchored in buccal tubes on the maxillaryfirst permanent molars and was adjusted to lie2ndash3 mm away from the labial surfaces of theincisors and canines and from the buccal surfacesof the premolars The children were instructedto wear their lip bumper day and night and to

remove it only for meals or for tooth brushingControl visits were scheduled every secondmonth at which time the position of the lipbumper was checked and adjusted if necessaryThe lip bumper was used passively ie it was notadjusted for active expansion

The effects of the lip bumper were docu-mented by measurements on dental casts andprofile cephalograms made immediately before

and after treatment The recording on the castincluded measurement of the width of themaxillary dental arch at the first permanentmolars premolars and canines The measuringpoints are shown in Figure 2 When the premolarsor permanent canines were not erupted thecorresponding points on the deciduous teethwere used No measurement was made when adeciduous tooth was replaced by its successorduring the period of observation The length of the dental arch was measured from a lineconnecting the tip of the mesiobuccal cusp of the


Figure 1 Type of lip bumper used for the treatment

















methods used


i) were calcu-


si = radicΣd22n







Results























Discussion









































References











































methods used


i) were calcu-


si = radicΣd22n







Results























Discussion









































References







































Discussion









































References



















































References



























eur j orthod 2000 hдsler 25 32

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