a-r--

MORPHOLOGICAL CHANGES IN THEDENTURE BEARING AREA FOLLOWING

h i t . d?nt . J . , 1974,116.225.

Alveolar Process; Atrophy; Denture, complete. immediate:Denture, complete, upperj Denture, partial, immediate:Denture , par t ia l . rcmorab le ; Mouth Muco\a : Pa la te :Too!h Extraction.

Materials and methods employed in the-study of posGextraction changes in the maxillary denturebeari-ng area are described. From an original sample of 7l patients, 25 were studied ot.i " f..ioaof 2[ years. The post-extraction dimensional changes are indicated in graphs, taUei-anAdiagrams.

-The changes in a sample of 12 immediate denture patients are compared with those in a sampleof 10 patients with dentures fitted after healing.

A s-tudy of spots tattooed,on the mucosa prior to extraction of teeth has made it possible toiden-tify the remnant of the lingual gingival margin in the edentulous mouth.

The constancy of the pre-extraction measuremtnt of the buccalJingual breadth of the alveolarprocess is noted, as is the usefulness of this measurement as a biomletric guide for futl d.nto."construction.

THE EXTRACTION OF MAXILLARY TEETHDAVID M. WATTI, prr .D. . F. r ) .s . . r r .D.D. , L.D.s.

PETER R . L IKEMANI , s .o . s . . r . o . s .

rHE atrophy of the alveolar process after theloss of the teeth is a matter of common observa-tion and it is apparent, from general clinicalexper ience. that the amount of the at rophicchange in the residual alveolar ridges and- therate at which it takes place vaiies greatlybetwcen individuals and between differeni partsof the same mouth.

Atthough the growth of the alveolar pro-cesses with the eruption of the teeth and-thedevelopment of the human jaws have beencarefully studied, the atrophic changes follow-ing the loss of teeth have ieceived siant atten-tion. Nevertheless, these changes are imDortantto the practice of prostheti i dentistry. Thedesign of prostheses to replace lost te;th andresorbed alveolar ridges is largely determinedby Lhe position and amount of moroholosicalchange in the denture bearing areas of the iawsand, to a certain extent, thebptimum time forfitt ing prostheses depends upon the rate ofcnange being minimal.

Review of the LiteratureLisowski (1944) used a tracing instrument tostudy morphological changes following toothextraction, but his use of a face-bow to orientatecasts wa-s a principal source of inaccuracy. Heobserved. jn 10 patients, approximately 2 mmDuccal and 2 mm lingual loss of contour of there^srdual alveolar ridge 2 months after extractionol ma4i l lary inc isors and canines.t;"n**"* ;-..,*",,u" Dentistry, University of Edinburgh.

MARCH l9 1974

. Harper (1950) described the changes observedin.the. study_of 'several cases' birt gave noindication of how many. He concludei (194g)that the inc is ive papi l la d id not change posi t ionup to 7 years after tooth extraction, but'did norpresent e_ngugh evidence to support this con_clusion. More recent work has-shown that theposition of the incisive papilla changes relativeto the vault of the palate after tooth extraction.

. Atwood (1957) in a radiographic study of 32denture-wearing patients estimated the com_bined loss of alveolar ridge height in the medianplane of maxilla and mandible varied from0.37mm to 1.26 mm per month before theinsertion of dentures and from 0.1 to 0.21 mmper month after insertion of the dentures.

Lam (1960) studied the resorption of anteriormaxil lary tooth sockets in 3 patients and usedthe standing posterior teeth to orientate succes_sive casts. He found 2.7 mm loss in heisht ofre_sidual alveolar ridge I month after extrictionot 'centra l inc isors and 3.7 mm af ter 5 months.The corresponding means of loss in labialcontour were 3.2mm at I month and 4.1mmat 5 months. He also observed that there wasno further change between the fifth and thetwelfth post-extraction months.

.Atkinson and Johnson (1962a and 6) des_cribed an instrument for cast measuring andsupported their use of a palatal index fo*r castorientation by producing evidence that serialcephalometric radiographs showed no changein the posterior part of the vault of the palate

22s

9y9! 3 years. Johnson (1963, 1964a, b, c ,1961,1969a, b, 1970) measured serial casts up to jyears. He found less resorption whcrr immediatedentures were inserted than rvhcn denturcs rveref i t ted at rhc end of the per iod of rapid resorDr ionl0 to 20 xeeks af rer e i t ract ion.

Wictorin (1964), in a 3-year study of 77patients by cephalometric radiography. alsolound less resorpt ion in cases rvhere immedi l tcdenlures uere f i t ted.

Macgregor (1965) carried out a cross-sectionstudy of the dimensions of 351 dentulous and300 edentulous maxil lary casts in order todesign impression trays. Some indication ofchanges follou'ing tooth loss can be obtainedby comparison of the mean neilsurements ofhis samples.

. Carlsson et al. (1967) reported on the reduc-tion of the maxil lary alveolar ridge underimmediate dentures in 38 patients. 6 monthsafter extraction, the cross-sectional area of thealveolar process in the median plane wasreduced by 23 per cent and by a further | | percent after 5 years. They observed that afrer 2years the reduction of the ridge from the oalatals ide and. f rom rhe r idge heig[ t proceeded moreraprdly than trom the buccal side. Thev alsoconfirmed the stabil ity of the radioeiaphicshadow of the posterior part of the hard-paiate.

Maxil lary ridge resorption has been studiedover periods in excess of 7 years after extraction(Atkinson and Johnson, l9j2; Tallgren, 1966,1961,1969,1972). These studies show rhat theanterior vertical ridge height may continue toreduce at a rate of 0.1 mrl a year or less,although in some cases it may apparently cease.

l\ laterials and NlethodsThe changes in the mucosal surface form of thcdenture-bearing area of the upper jaw, followingthe extraction of teeth, rveie observecl in alample selected from patients attending theP,rost hodo nt ic Department of Fdi nburgh I)entalHospital. Impressions were taken before and atintervals after the extraction of teeth. Verticalsection traces of the pre- and post-extractioncasts were made as follows:(l).Tracings in sagittal planes: through themedian plane and central incisors.(2) Tracings in coronal planes: through canincs,first and second premolars, first, sEcond andthird molars.

In each series of casts, tracings were madeonly where teeth were present at the com-mencem€nt of the study. The post-extractiontraces were super imposed in turn on the equi_valent pre-extraction trace and measurements

226

rnade ol the post-extraction changes for eachtooth rernoved.

The SampleSe.venty-one petients were selected, the onlycrrterion being that they requirccl the extractionol at lcast 4 maxil lary. teeth. pre-

.and p:lst_extraction impressions \\,ere taken cif '

' these

patients, rvho attended the clirric at varyingtirrcs, in diminishing numbers, as the siuc.tvprogressed. It was p-rrticularly dil lcult t;persuade sonte of the paticnts to retrLrn forfurther impressions after dcntures had becnfitted and ntany of the series of casts terminatedat that point; as a result. onlv l5 n.rales arrcl l0females had adequate series of casts extenclinsover pcriods of 2] years or more. The postlextraction intervals at u,hich thc casts wercmade varied considerably betrveen patierrts andbetrveen different groups of extraCtions in thesame patient. Nevertheless, as far as possiblc,an attempt was made to obtain casts at lbrt-nightly,intervals for thc first 2 months, at 3, o,9 and l2 months after extraction and, thereafter,at 6-monthly in tervals . A tota l o f 1,2g5 ver t ica lsection traces were made of 206 casts froru 25patients and comprise lhe rnaterial fbr thisstudy.

All the teeth includcd in the sample ryereextracted rvith forceps and no bone ir. imrningor suturing rvas carried out. Teeth rvere ex-cluded fronr the study if they u,ere fractured orif there were surgical diff icult ies involving bonetrimming or suturing, or i l there q'ere o-bviouspre-extraction swell ings or faults in the pre-extraction cast. No ntcdian plane trace rvasmade rvhere one incisor rvas missing befor-c thestart of the study as the remaiiing incisortended to drift across the median plane andintercept the plane of thc tracing.

All the impressions u'ere taken in alginateand were cast immediately, using equal quar.r-t it ies by rveight of plaster and Kaffri D. lZ otthe patients were fitted with full or partialimmediate dentures and l3 had denturcs fittcdat periods varying from 14 to 52 rveeks afterextraction. All the dcntures were made ivithlabial f langes and the immediatc dentures didnot extend into the extraction rvounds. In ordcrto minimise any change produced by the dcn-tures, particular attention was paid to theirocclusal balance and fit, which rvere checked atevery visit. Patierrts were requested to leavetheir dentures out at niqht. and rhat this rvasbeing done rvas checked-by questioning at elchvis i t .

The'Stable Area of the Palate'It rvas essential that the casts were mounted on

RRITISTI DENTAL JOI-IRNAI

--r4as

1,

t

the .tracing instrument as nearly as possible inan identical manner. Differences of antero-posterior or lateral tilt would result in thetracing point passing over parts of the serialcasts which were not equivalent to each other,and would invalidate any conclusions drawnfrom a comparison of the traces. The accuracyof the mounting of the casts was thereforefundamental to the study and the method usedwas based on radiographic evidence that littlechange took place in the vault of the hard palateduring the period of investigation.

There was, however, no evidence for thestability of the mucosal surface covering thepalate; a careful study was therefore made ofthe 25 pre-extraction and 181 post-extractioncasts of this study, together with 46 pre-extrac-tion and 138 post-extraction casts from incom-plete series. These 7l series of casts werestudied with a hand lens. At least 4 points in themucosal pattern which could be clearly identi-fied throughout each series were marked on eachcast in an area bounded anteriorly bv the thirdpair of rugre, laterally by sagittat ptaires l0 mmfrom the mid-line, and posteriorly by a coronalplane 5 mm anterior to the posterior border ofthe hard palate. Comparative measurementswere then made between the points on the castsof each series. On everv cast of each series atIeast 4 such points could be identified whichmaintained their relationship to within 0.3 mm.This was accepted as evidence of the relativestability of the form of the mucosal surface inthis area of the palate.

_ It,is recognised that stability of any part ofthe human body is only a relative value and itis not implied tiat changes were totally absentin the 'stable area' of the palate but rather thatthe changes over the 2! y,iars period of the firstpart of this study were negligible when com-pared with those of the alveolar ridges, so thatvalid measurements of morphological changesfollowing tooth extraction- could be maderelative to this area. The vertical tracings werethen arranged to cross this stable area ii everycasl-of a series, so that, by superimposing thestable portions of the traces, changes whichoccurred in the other parts could be measured.The Refererce PlanesIn order to position the tracings of each series'accurately, each cast was considered to bedivided by two imaginary planes which inter-sected each other at right angles (fig. l). Thepldrtes selected were the 'median' plane, asdefined by one anterior and one posteiior pointon the median raphe. and a coronal 'reference'plane, which interiected the median plane within

MARCH 19 1974

Frc. l.-The median sagittal and reference planes.The M and R points are on the stable part of the palate.

the stable arca at a point (R) near the medialends ofthe third and fourth pairs ofrugr.

On each sagittal trace, the point at which itintersected the reference plane was indicated bya vertical line (R line) and on each coronal tracethe intersection with the median plane wasindicated by a similar vertical line (M line). TheR point, which represents the intersection of theR and M planes on the surface of the cast, wasselected by finding on the median raphe nearthe ruga a characteristic detail which was easilyidentifiable on all the casts of a series. Thepoint was confirmed by a constant linearrelationship to other defined points within thestable area. The posterior M point was simi-larly placed on a permanent surface configura-tion on the raphe near the posterior border ofthe hard palate not less than 5'mm anterior tothe vibrating line. This point, together with theR point, defined the median plane.

Mounting the CastsEach of the casts to be traced was mounted ona 9 cm square Perspex base with impressionplaster. A mounting jig with four adjustablepointers was used (fig. 2).'The pre-extraction

*ilt

I

I, :

I Frc. 2.-The jig used for mounting series of casts to anidentical orientation on machined Perspex bases.

227

cast was set up with the occlusal plane hori-zorLlll. The posterior pointer of the jig waspositioned on the M point, the anterior-p-ointeron the R point and fhe cast secured to'the j igby an elastic band passing undbrneath it. Twolateral pointers, placed 5 irm either side of themid-line, contacied the surface of the palatewithin the stable area to maintain the positionof the cast. From this position, the iast wasIowered into a mix of impression plaster on thePerspex base. The level of each cast wasidentical as it was determined by a stop on themounting jig. Each Perspex base was oiientatedin an identical manner by a set-square clampedto the table of the instrument. The side of ihebase. was set parallel to the median plane. Eachof the casts in a series was positioned on thejig in turn and secured to d separate perspexbase.

The Tracing Instrament (Figure 3)The base of the instrument for making thetracings was an engineer's surface tablE. Avertical steel plate, the paper holder, was boltedto the back of the table. The traces were madeupon papers which were fastened to this holderby button magnets. The main part of the instru-ment comprised a double jointed, counter-poised surveying arm clamped to the right sideof the table. This arm mov-ed in a plane*parallelto the-surface of the paper holder. At fhe freeend of_the surveying drm, a cranked rod passedthrough two bearings and rotated about ahorizontal axis which remained pemendicularlo the surface of the tracing paper no matterwhat the _ position of the suiveying arm. Astylus with a rounded steel point oT 0.75 mmJiameter was fixed to the iront end of the;ranked rod in such a manner that the point lay

exactly- in the axis of rotatiol of the,rod. Thus,the stylus_could be rotated through 360., movedup and down, and from side to side, but re_mained in a vertical plane parallel to and 20 cmIrom tne traclng paper.

A pen of the type used. in barographs wasmounted on a spring-loaded hinged bar attachedto the other end of the surveying arm. Thespring held lhe pen.away from the tracing paperbut pressure on a button on the right or oir alever on the left of the table activated push rodswhich brought the pen into contact with thepaper in the same axis as the stylus tip when atrace was made.

The casts were positioned on the table by asteel bevel which located the same corner of ihePerspex base as had entered the set square onthe mounting instrument. The short arm of thebevel was held in close contact with the left sideof the table where it registered on a millimetrescale and guided the whole back or forth in apath normal to the paper holder.

The traces from the first cast of a series weremade-on millimetre-sqr,ere graph paper. Theyprovided thc baselines from which post-extrac-tion changes were measured. Subsequent tracesfrom the post-extraction casts were made ontracing paper so that they might be super-imposed on the equivalent pre-extraction traces.After tracing the median plane and beforemoving the cast or the paper, the vertical R linewas marked to indicate the position of the refer-ence.plane. The cast and the locating beveltogether were advanced to bring each-of thecentral incisors in turn into tho plane of thetracing point. The position of these traces wasnoted on the millimetre scale and the R linemarked to indicate the position of the referenceplane on both of these tracings.

The cast was then turned through a rightangle so that the tracing point m-oved in acoronal plane and tracings were made througheach of ihe posterior teelh in turn, their poii-tions again being noted on the millimetre scale.The M line was marked on each trace in thesame way as the R line on each of the sagittaltracings. Only the lateral incisors were totallyexcluded from this investigation, as sagittaltracings of these teeth did not cross the stablearea of the palate. Coronal traces anterior tothe R plane were assumed to fall entirely in anarea subject to change and were superimposedby relerence to the vertical change indicated onthe median sagittal plane trace at the pointwhere it was crossed by the coronal tracing.

Repetitive tracing of the pre-extraction castwas avoided by superimposing the post-extrac-

tc. 3.-The tracing instrument. A tracing being madein the coronal plane.

228 BRITISH DENTAL JOURNAL

tion traces in turn on thc pre-extraction traceand making direct _contact photographs. Meas-urements \{ere made on the dev..loped negatives

using a Brinell microscope calibrated in tenthsof a millimetre. The poJitions of measuremintare shown in figurc 4a, b, c.

#

b

)

_ GFtc' 4'-Measurement of ,the traces: a, sagittal ptane; Q, coronal plane anterior to the stable area of the palate;c, coronat ptane crossine the- stabte are:a;t ih; i;dt.: iti:i;;iiffii,iiiii'iilr*"rnents: RH ridge height; BLBbucco-linguat breadth: IpB,}]ll1t-""r b;fiih:-ilrj ;;6t3f ;,6td:-Foiij"ii'.""tion measurements: B (u, m, l)09cqal:-upper, middle a-nd .lower mquurements; ihe mein oi irtiiE rc'.t o"*o-as buccat change;- LV verticat changeot the lingual gingival margin; p palitat ttringi, iruniu.tr. or sagittal in the plane of the tracing; MV median vertical.

MARCH 19 1974 229

-' . +

ErrorsCalibration exoeriments were conducted toinvestigate the 6rrors from variations in mount-ing the casts and superimposing the traces. Themean error of the former varied betw'cen 0'2 mmand 0'5 mm, depending on the position ofmeasurenent. The mean errors of superimposi-tion varied bet*.een 0'1 and 0'3 mm.

The post-extraction intervals at tvhich thetraces were made varied from patient to patientand, in order to compare them, it was neccssaryto construct graphs of post-extraction changeplotted against time. Graphs of buccal change,lingual vertical, and palatal change, rvere madefor every region of the mouth traced in each

patient. The changes over 2] years at each olthe 8 regions traccd are shown in Tables I, l land III and are i l lustrated in tigures 5, 6 and 7.These diagrams were made from the traccs olthe patient rvhose measurenlents werc nearestto the mean for the rvhole sample. Thc traceswere altered exactly to coincide rvith the meansat the positions of measuremcnt.

Observations and Discussion( I ) Rate of Change

For every tooth extracted the amount of changeof contour was plotted against t ime and 3ilgraphs were constructed to enable post-extrac-tion changes to be studied. In every case, a

(

I 'Aal E I . AVERA(jE Posr-EXtRACTtoN CHANCES IN SAcrrrAL -I

RACrs rN MFDIAN PLANE AND THlroucH 1l l

I r( n

t

39 52 78 10.1ntil nt|il tnnt nlnr

1 . 0 5 3 2 0 3 . 3 5 3 5 0

52 78 10.1ililt tnill tltIl

4 U 0 5 . 1 0 5 . 3 0nlnl Dlln

B u c c a l 1 5 0 2 3 0

1 . 8 5( n - 1 5

r - 2 8 )

52 78

3 . 7 5 3 9 5

2 4n lm t tn l

1 . 1 0 t . 1 5

N l e d i a np l a n e( n - - 1 8 )

l l 0

3 6 0

2 . 3 0

9 3 5

3 2 5

F r c ' . 5 . -sagi t ta lrlonths

FrLi . tcanineand 3(

faplct ion,decrtext raaverib,u" ela s pyean

\11

.37) L insua lv e r t i c a l I l 0 1 4 2 1 6 0

B u c c a l

L i n g u a lv e r t r c a lS a g i t t a lp a l a t a lB u c c a l

L i n g u a lvert icalM e d i a nv e t t r c a lB u c c a l

L i n g u a l 0 8 0 1 3 5ver t i ca lT r a n s v e r s e 3 0 5 4 3 5pa la ta lBucca l 0 '60 1 00

L ingua l l ' 20 1 65verticalTransverse 2 '75 4 45palataln:number of patients in sample.t : number o f tee th in sample .

B u c c a l

I ' inrc in ||?eks since \l! e.Ylrttction2 4 6 8 1 2 1 6 2 6

nrm nlnt nlnr m4l illnl n|Dl nltlr

0 8 0 1 2 5 1 . 6 0 1 . 8 5 2 . 2 0 2 4 0 2 . 8 0

0 3 5 0 6 5 0 8 0 0 . 9 5 l . l 5 1 3 0 1 . 6 0

1 9 0 2 . 9 0 3 5 0 3 . 9 0 5 0 5 5 8 0 6 8 0

0 . 6 0 0 9 5 1 . 2 5 1 5 5 1 . 9 5 2 . 2 0 2 . 5 0

I 8 5 l . 9 i 2 . 0 5 2 2 0'1.' �70 8.20 8 65 9 00

2.65 2 75 2 85 3 .00

( n - . 9t : 1 6 )

S a g i t t a lp a l a t a In : n u m b e r o f p a t i e n t s i n s a m p l e .t n u n b e r o l t e c t h i n s a m p l e ,

TABLF I l . AVLRACF Posr-ExTRACTIoN CsaNcrs rN CORONAL TRACES rHRoucH CANINtis AND PRIMOLARSTitne in ||ceks sii lae ettraction

6 8 1 2 1 6 2 6 3 9nttt nlnt ttm l/lnl ltxtl nlll1

2 6 0 3 . 0 0 3 5 5 3 . 8 5 4 . 2 5 4 . 6 5

2 . 5 5 2 . ' � 1 5 3 . 1 0 3 2 5 1 . 5 0 3 . 7 0

0 6 0 0 7 5 0 9 0 0 . 9 5 I 1 5 1 . 3 0

I .20 I .45 I 90 2 20 2 .65 2 85

I 7 0 2 0 0 2 3 5 2 6 0 2 . 9 5 3 1 5

5 . 3 0 6 . 2 0 7 6 0 8 8 5 1 0 . 4 5 I 1 0 5

1 3 5 I 6 5 2 . 1 5 2 . 4 5 2 . 8 5 3 ' 0 0

2 . t 0 2 . 3 5 2 . 7 0 2 9 s 3 . 4 0 3 . 5 5

1.70 1 .92 2 00 2 28 2 48 2 .65 2 .78 2 .90 3 00

3.30 4 70 5 .40 6 .05 ' �1 .35 8 05 9 '00 9 85 l0 30 l0 75 I I l0

1 3 0

5.6-s

1.40 2.20

0 2 5 0 5 0

0 50 0 .85

3.90 3 9_5

1 . 5 0 1 . 5 5

3 . 2 0 3 3 5

3.50 3 60

12.25 r 2 50

3.40 3 55

3 . 8 5 3 9 5

1 1 . 7 0 l l 9 0

r . 3 5 1 . 4 5

2 . 9 0 1 1 0

3 . 2 5 3 . 1 0

i l 35 1 1 .90

3 1 5 . 3 3 0

3 6 5 3 . 7 5

1 t 1 l 1 1 . . 1 5

(

(

nX(_

4 l {( n : l 5

t 1 6 )

6 6( n : 8

r l l )

230

5.55 6 35 ' t .25 8 . 0 5 9 4 5 1 0 . 1 0

TABLE II I . -AVERAGE Posr-ExTRACTIoN CHANcEs IN CoRoNAL TRAcEs rHRolrcH THE l \{oLARsTine in wceks since exlra.l ion

6 8 1 2 1 6 2 6mm illnl lnnl mD1 llolt

2 . t 0 2 30 2 60 2 .80 3 20

3 9

3 . 4 5

10,1 130

4 . 1 0 4 . 2 0

7 7( n - . 9t =. 1.1)

E 8( n - . 8r - 1 2 )

L i n g u a l 0 8 5 1 ' 4 5 1 9 0 2 1 0 2 3 0 2 4 5 2 7 o 2 9 O 3 l 0 3 2 0 3 4 0 3 4 5vert lcalT r a n s v e r s e 3 . 0 5 , 1 4 0 4 9 5 5 3 5 5 8 5 6 2 5 7 1 0

' 7 7 O 8 0 5 8 4 0 9 2 5 9 4 5pa la ta Ib u c c a l 1 0 0 1 8 0 2 1 5 2 9 5 3 , 1 5 3 6 5 4 0 5 ' 1 3 0 4 4 5 4 7 0 ' 1 . 9 0 5 . 0 0

L i n g u a l 1 2 0 1 6 5 2 0 0 2 2 5 2 5 0 2 6 5 2 8 0 2 9 O 2 9 5 3 1 5 3 3 0 3 4 0vert icalT r a n s v e r s e 3 9 0 4 ' , ' O 5 . 2 5 5 7 0 6 4 5 7 0 5 7 9 5 8 6 0 8 9 0 9 1 5 9 3 5 1 0 2 5pa lJ l f , l

b u c c a l 1 7 0 2 ' 3 5 2 6 0 2 8 0 2 9 5 3 1 0 3 4 0 3 5 5 3 6 5 3 8 0 4 0 0 4 1 0

L i n s u a l 1 4 5 1 6 5 1 8 5 2 . 0 0 2 2 O 2 3 0 2 5 0 2 5 5 2 6 0 2 ' 7 O 2 8 0 2 8 5verticalT r a n s v e r s e 3 9 5 5 0 5 6 0 0 6 8 5 7 6 0 8 0 5 9 0 5 9 7 5 1 0 6 0 l l 2 0 l l 4 1 l ' 6 5palataln:number of patients in sampl€t :number o f tee th in sample ,

BRITISH DI]NTAL JOURNAL

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Irrc.. 5.-Average changes in median sagittal plane an<lsagi t ta l p lane through centra l inc isor 1, 3, 6, f2, and 3Omonths post-extraction.

Ftc. 6.-Average changes in coronal planes throughcaninc^, first premolar and second premolar 1, 3, 6, i2,r rnd 30 months post-exl ract ion.

rapid change was observed shortly after extrac-tion, and there was a general trend towards adecrease in the rate of change as the Dost-extraction time increased. An a-ssessment of theaverage rate of change in the samples was madeby expressing the average changes in each regionas perc^entages of the average changes at 2$years after extraction.

MARCFI 19 1974

Ftc. 7.-Average_ changes in coronal p lanes throughf i rst molar , second molar and th i rd molai l , 3, 6, 12, a;d30 months post-extraction.

The figures may be shown by the followirrgapproximate modal values:

40 per cent by the end of the firstpost-extraction month ;

65 per cent by the end of the thirdpost-extraction month;

80 per cent by the end of the sixthpost-extraction month ;

90 per cent by the end of the twelfthpost-extraction month.

, The average post-extraction changes over the8 regions appeared to be slightly less in malesthan in females, but in view of the small samoleand the large range of the observed changes ihedifference was not of importance.

(2) Main Dimensional Changes(a) Two-and-a-half years after extraction of theteeth_, the ayerage buccal change in the sampleof 25 patients was approximately 3.5 mm in ihemedian plane. central incisor and premolartraces, and 4 to 5 mm in the molar trates.(6) Th9 average vertical loss of height (lingualvertical change) 2! years after extraction wasbetween 3 and 4 mm in 7 of the 8 resionstraced, but in the median plane the meaiure-ment was 2.3 mm. The smaller measurement inthe median plane rvas chiefly due to absence ofgingival margin collapse in the region and alsoto the forward movement of the incisive papilla

.presenting a change in contour at the p-osftionoI measurement.(c) The atrophy of the residual ridges affectedthe shape of the palate and its contour in agiven plane widened as the atrophy of theridges progressed. The area of the palate

231

affected by change extended towards the centreof the palate until only a relatively smallmedian area remained unchanged 21, yearsafter the extraction of the teeth. On average,this area was roughly boundcd by a line drawnon the surface of the palate about I cm fromthe lingual gingival margins (flg. 8.)

Frc. 8.-The part of the palate which remained stableover the 212-year period of the study is indicated by thestippled area on the diagram.

At the end o[ 2! years study, the palatalchange was still progressing slowly. Furtherdiminution of the stable area was, therefore, tobe expected in studies covering a longer period.

(3) Gingival Margin Collapse

General observations showed that in every casethe buccal and lingual gingival margins col-lapsed towards the sockets when the teeth wereexlracted. This was reflected by a dip in thegraph of lingual vertical change shortly afterextraction and thereafter the change proceededmore slowly (see fig. l2). In the median planethere was naturally no such collapse and thefirst part of the graph showed a more gentleslope than in other regions of the same mouth.

A number of the tooth sockets studied showeda surface concavity when they were first healedbut as the healing progressed the concavitybecame less obvious. This was chiefly due toshrinkage of the margins but partly due toproliferative change within it.

(4) Efect of DenturesIf dentures are to be fitted a short time after theextraction of teeth, it is advisable to fill thedepressions on the cast with plaster so as. notto inhibit any proliferative change. In thosepatients who were fitted with immediate den-tures, the casts were trimmed so that there wereno depressions and a smoother ridge resulted.

232

Frc. 9.-series of tracings through the iS region of onepatient. The denture was fitted at l6 weeks post-extrac-iion and it can be seen that the surface concavity at thattime is still in evidence at 158 weeks.

l6 weeks alter extraction. the depressed scar ofthe extraction wound was preserved by the formof the denture throughout the 3-year period. Inthe immediate denture case, the ridge had beensmoothed on the cast and it can be seen that thesmooth contour was preserved throughout theperiod of study.

(5) Immediate Dentures

When removing teeth from the cast beforemaking immediate dentures they should be cut

1 week

6 wks

10 wks

18 wks

20 wks

28 wl(s

43 wks

60 wks

158 wks

BRITISH DENTAL JOURNAL

A series of tracings through a first uppslmolar where the denture was fitted t0 w-eiksafter extraction, and through a first premolarfollowing the fitting of an immediate dentureui" rho#n in figures"9 and 10. tn the case dttei

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Frc. 10.-patient.

'I

to the Plsocketing.

F r c . l l . -plaster terconstructlinterrupt(

off at tlcated inportionthe congum fittwith unbone. Iing denl

L"+-rwt.+rL-+JwWW

Frc.. 10.-Series of tracings through the { l region of onepauenr. I ne smooth contour of the r idge is attr ibutedto .the provision of an immediate dinture *i i troursocketing.

Frc. I l .-Diagram i l lustrat ing method of removal ofplaster teeth lrom the cast prior to immediate denturemnstructio.n.. The cast is trimmed as indicated by thernterrupted lines.

off at the level of the gingival papi l le as indi_cated in the.diagram (f ig. I | ) ani i fhe remainingport ion of the tooth should be carved to fol lowthe contour of the r idge. Cutt ing sockets andgum fitting the teeth usually resu-lts in a ridgewitlr. uneven thickness of mucosa overlying t[ebone. This provides poor support for iuiEeea_rng dentures.

MARCH 19 1974

A sample of l2 imnrediate denture pat ientswas comptred with a sample of l0 patients withdentures fitted after heaiing. The amount ofbuccal and vcrtical cha.ngc in the central incisorlegion is i l lustrated in the graphs in figure 12.The stippled areas.representlhe range oichangeobserved in the whole sample. ThJcontinuouslines represent the change in patients withimmediate dentures and ihe intcrrupted l inesthe changes in pat ients wi th dentures f i t ted af terhcal ing. l t can be seen that s l ight ly less changetook p lace in the pat ients wi th immediate dei_tures, but statistical tests indicated that thedifference was not significant. It can be seenthat the difference between the immediatedenture patients and the ordinary denturepatients diminished with time, so that. at 2lyears, the difference was completely negligible.(6) Changes in Incisive Papilta and RugeA change in the position of the incisive panil larelative to the stable area of the palate

'*as

observed in every case fo l lowing the extract ionof the maxi l lary centra l inc isors-and changcs inthe shape of the prpil la were also fouid toaccompany thc loss of these teeth.. On average. the papil la moved forward about1 .6 mm ( range 0 .6 t o 2 .7 mm) and uDwardsabout 2.3 mm (range 1.3 to 4.0 mm). Thismovemetrt of the papil la has an importantlmpttcatlon. As rcsorption proceeds, the rela_tions.hip between the

-incisive ptpil la and the

incisive fossa changes. Thc foisa tends tooccupy a.more posterior position as the boneresorbs while the papil la moves forwards. Thus,the lossa tends to l ie poster ior to the prp i l la inthe edentulous mouth.

The inc is ive prp i l la prov ides a roush guideto the posi r ion of the nraxi l lary caninc i . I i i thede.ntulous- mouth, a coronai plane through themiddle of the papilla generally passes th"roughthe canrne crowns but after the teeth are lostthe canines should be located in a coronal planepassing through the posterior border oi thepapilla. The so-called canine eminence in theedentulous mouth often lies distal to the truecanine position. particularly where there hasbeen much resorption. It is formed by thebuttress of bone between the larger caninesocket anteriorly and the sma-ller firs-l oremolarsocket posteriorly.

. Changes in the position and shape of therugre followed the extraction of anteiior teeth.The g.reatest change took placc in the first pairo l 'pnmary rugie ' (Lysel l . 1955), which appearedto be carried forward and upwards *iitr tt epapilla by the hinge like .movement of themucosa concomitant with the underlying bony

2 weeks

4 wks

8 wks

12 wks

27 wks

44 wks

142 wks

r.:.?-r:

RANGE & AVERAGE VERTICAL POST'EXTMCTION CHANGES AT LINGUAL G!'IG[VA- MARGIN

IN SAGTTTAL TRACES THROUGH !IL.

(r) mrrevrs wrIH |MMED|ATE DENTURES n=12 (e) PATTENTS WTH DENTURES FITTED AFTER HEALING

TIME IN WEEKS SINCE EXTRACTION OF III

3 9 9 7 4

E - l

u( r -z

change. A similar forward and upwards move-ment of the second pair of ruge also occurred,but later than in the case of the first pair. Thechange, hou'ever, was usually evideirt by the26th post-extraction week. In some cases thelateral ends of the third and fourth pairs ofruge wore observed to move upwards an.dlaterally, especially when the ruga were long.These movements of the rugr are significant,as changes in their position under denturesleads to pressure upon them. This causesflattening of the rugre and occasionally patientsexperience discomfort in the ruge area. Thefirst and second pairs of ruge are chieflyaft-ected.

In cases of extreme resorption, the residualalveolar ridge disappears entirely and the softflabby ridge which is left does not comprise anyalveolar tissue but is composed entirely of thesoft tissue of the palate. The ruge may be seenforming transverse ridges across the anteriorpart of this so-called 'soft residual alveolarr idge' ( f ig . 13) .

(7) Tattoo Spot StudyIn 8 patients of the sample, a tattoo spot wasplaced near the gingival margin on the buccaland lingual side of each tooth before extraction.A total of 110 spots were tattooed. The move-ments of the tattoo soots indicated that the

234

Frc. l3.-L,xtreme resorption of the maxilla in whichthe rugrc may be seen crossing the residual ridge whichis norv composed entirely of former palatal tissue.

sreatest reduction in mucosal surface area tookilace in the areas of the extraction wounds.Scar tissue contraction in these areas may havecontributed to the observed changes in thepositions of the rugre.

It was evident, from the study oftattoo spots'that the remnant of the lingual gingival rnarginscould be easily identified on edentulous casts(fig. 1a). Itwas also evident from pre-extractionmeasurements (BLB, fig. 4) in this and anotherstudy (Watt et a|.,1961) that the between patientvariation of alveolar'breadth at each toothposition was relatively small (Table IV)' Thus'

ERrrrsu DENTAI- JOURNAL

I - .u

RANG€ E A/ERAG€ zuCCAL POST.EXTRACTION CHANGES IN SAGITTAL TRACES THRO{JGH IIL.(A) hT|ENTS MTH |MMEDTATE DENTURES n-r2 (B) PATTENTS WrTH DENTLRES FrTED AFTER HEALING n.lo.

T|ME rN WEEKS Sll.|CE EXTRACTION OF ll l .

t 5 2

t A w

Frc. 12.-Comparison of lingual vertical and buccal change in sagittal planes through centralincisors in natients with immediate dentures and dentures fitted after healing of sockets. Thestippled areas represent the range of change observed

E

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Frc. i4t o 4 i ycast tn(and thindicatrrequire

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ever biras tae\tractherefiand repositir

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TABLE IV.-ANALysrs oF MEAsuREMENTs oF HoRIzoNTAL BREADI

,,,,,,,,;,; o:;;' :ii:li;:[::il'i3'lH: ?'l If" S.I^Y,'3.?],'J":,::$': FR.M rHE Ltxcuar crNG,vAL MARGTNS ron Min Max x SO

central incisorsagittal oR *,\ n:m_ mm mm

!fi:i?::,T,:?'"..."", ip ;! lii f i ? Bl.i::#jT#iJlf :nf,X'"" ;3 ;:i l3:i i3B llig+ru j{145 coronal sectionirrrst morar coron"t 119 .q ! 13 6 10.3 1.27

ii::t*T,?'i:j:j:tit j! 'i 3 i19 I?2 ??i'Molai iegton'combined data 45 7 4 ic o lo.t 1.33

EZIZS coronal sections rc6 7.g 14.3 lt.O 1.37

who made the instruments which were used inthis study and who provided *""f, t".[ni"ufassistance. We also wish to-thant Mia.liuot"r,Y. R. Renton and Miss M. il;;;;?Jr'th"illrrstrations, and the many otherun"mOeis ofstaff of the University of fOinUuig-fr- *f,o i,uu"rn some measure assisted us in thiiwork.

REFERENCES

Atkinson. H. F.. and LoJlj l^.gn, I. (t962a) Aust. dent.J.,7.3t0.( l 9 - 6 2 b t A u s t - d e n t - J . , j . f S f . " - " ' - ' " .

(1972) eut. dent. J.,17',140',Atwood, D. A. (1957) J, prosth. Dent.,j,544.tlttii:."' E., Rognarson, N., and Astrand, p. (1967) oclont. 7.,

Harper, R..N. (.19_48) J. dent. Res., 27,661.(t950) Dent. Items,72, i!2i.

Johnson, K . (1 .963\ .Aus t - dcn t . J . ,g .42g.- ( . ! l y .q ) Aus t . dcn t . J . ,9 ,6 .- l t vb4b) Aus t - dent . J . ,9 , 127.- .{! le-!ct Ausr. dent. t.,g, j iz.

- t,179!.Aust. dent. J-,"12, 152.- \ , t :9 t^q l Aus t . dent . J . ,14 ,241.- t. le^9??t Aust. dcn,. J.,14,3j0.'-......._ (1970) Aust. det. t., tS,'CAl.'Lam, R. V. (196O) J. prosth. Dent,,tO.25.Lisowski. C:S. (1944) A Compararive Study of the Resorption ofA,iveotar Ridge.Tissue under'tmmeai"i i-o'.ri". lr. v.i i .S."it"rir,Northwestern University, Chicago.Lysell, L. (1955) Acta odont. scand.,13,6, suppl. lg.Macgregor, A._ R. (1965) The Size and Form of Dentulous and

Ff, :fi ,li:i,,,.rt:i"::rff ,;f i..nr,, jl:o*.ien"i'rii,i.!',',iti?,uv..Taffgren, A..^(_1966\ Acta odont. scand.,24. 195.

\rto t ) Actq odont. scand., 24, 563.t !e^99^t 4fra odont. scand., 27, 5i9.\ t9 tz t J . p rosrh . Dent . ,21 , 120.

WlIl;^?:,Y.-q?gO) Morphologicatchanges in the denture bearins areai?'f}'Jf"lli.t-"action

ormaxillarv ieeth. Ptr.D. itrerii-trni"?i.tty

(1970) Anglo-coruin. dent. Soc. Newslerter.23. l0-(r-.L),#:'rdij c' M" and Adenubi' i'-ij."irb61i'i:"*. uoe.

Wicroritr. L. (1964) Acta radiol. (Stockh.),228. 1.

\uuuuu\lNuur\\!lu\l\\u[[l\

Frc.., l4.-Ser-ial casts showing tattoo spot positions upto 4$ years after tooth extraction. The arrow in tfr" tu.tcast rndicares the remnant of the linguil gin;iv;i ;a;;rn,and the measurements B.r-.r. on first and last castsindicate- the toss of tissue ana nence irr! irri#i.ri?tr,required on the edentulous cast.

it is possible to estimate more accurately thaneyer before the amount of buccal chanee'wiiichhas taken place in patients fo, *t o--no o."-extractlon casts are available. Dentures

^can

therefore be designed to restore the lost tissuesanc. replace the teeth more nearly in their correctposrtlons (Watt, 1970).

ACKNOWLEDGMENTS

We are particularly indebted to Mr J. Copland

MARCH lg 1974235