Gingivectomy versus flap surgery:the effect of the treatment ofinfrabony defectsA clinical and radiographic study

George Proestakis', GoranS6derholm\ Gunilla Bratthair,Boel Kuilendorff, KerslinGrondahP, Madeleine Rohlin^ andRolf Attstrom'Departments of 'Periodontology and "OralRadiology, Faculty ot Odontology, Universityof Lund, ^Department of Oral Radiology,Faculty of Odontology; University ofGoteborg, Sweden

Proestakis G. Soderholm G. Brattkall G, Kullendorff B. Grondahl K. Rohlin Mand Attstrom R: Gingivectomy versus flap surgery: the effect of the treatment ofinfrabony defects. A ctinical and radiographic study. J Clin Periodontol 1992: 19:497-508.

Abstract. The aim of this paper was to compare the short-term results ofgingivectomy (GV) and modified Widman flap (MWF) surgery in the treatmentof infrabony defects. 14 patients with 68 bilateral infrabony defects were selected.At baseline, and 3 and 6 months postoperatively. assessments of oral hygiene,gingival conditions, bleeding on probing, probing pocket depth and attachmentlevel, were recorded. Conventional radiograps were obtained in a way that assureda reproducible projection geometry. In a split-mouth design, one jaw quadrant wasrandomly treated with GV. while the contralateral with a MWF. The changes ofthe bone tissue were assessed by means of conventional and subtraction imagesby 2 observers. The interobserver agreement of the conventional and subtractiontechnique was studied. The majority of the sites demonstrated a significant improve-ment in gingival conditions and a reduction in bleeding. For both treatments,probing depths were reduced by an average of 3 mm. while a mean of 1.22-1.35mm of probing attachment gain was obtained. The GV resulted in slightly moregingival recession (1.90 mm) than the MWF {1,60 mm). The radiographicexamination demonstrated gain of bone in 7 defects treated with GV and in 9defects treated with MWF, This study demonstrated that pockets associated withinfrabony defects can be successfully treated by both treatment modalities. Fur-thermore, bone gain can occur after treatment but not in a predictable manner.

Key words: periodontal healing; infrabony de-fects; surgical treatment; clinicai measure-ments; subtraction radiography.

Accepted for publication 6 August 1991

Periodontal surgery is a valuable toolto achieve healing of the periodontaltissues. The need for accomplishing di-rect access to the root during the treat-ment of periodontally compromisedteeth justifies the incorporation of dif-ferent surgical procedures in the oper-ators armamentarium.

This need is particularly acute incases where infrabony pockets are pres-ent. Following treatment of these de-fects, discrepancy between the form ofthe soft tissues and the irregularly re-sorbed alveolar bone can be expressedas increased pocket depth (Prichard1961. Ochsenbein 1977). Thus, it may benecessary either to recontour the bonystructures or the soft tissue in order toovercome this discrepancy, or to achieverepair or regeneration of the perio-dontal tissues,

A large number of studies has beenperformed to evaluate the healing poten-

tial of the periodontal tissues after surgi-cal treatment of infrabony defects. Elle-gaard & Loe (1971) treated 191 infra-bony defects with flap procedues. Theyfound. 6 months postoperatively, com-plete bone fill, assessed by periapicalradiographs, and gain in probing attach-ment in 70% of the teeth exhibiting 3-wail defects. 40% of the teeth with com-bined 3- and 2-wali defects and in 45%»ofthe teeth with 2-wall defects. Poison &Heijl (1978). treated surgically 15 defects(seven 3-wall and eight 2-i-3-wall ones).The mean initial defect depth was 3,5mm. At the time of re-entry operation,regeneration of bone tissue was ob-served, with a mean amount of bone fillof 2,5 mm. The same successful outcomeregarding bone regenerat was achievedby Rosling et al. (1976a. b) in patientswith a high standard of oral hygiene.

Smaller amounts of bone fill (1.2-1,4mm) and gain of probing attachment

(1,2-2.0 mm), were achieved m otherstudies (Renvert & Egelberg 1981.Renvert e t a l 1981). Isidor et al, (1985).treated 43 angular bony defects withflap procedures in 3 of the 4 quadrantstested, while the 4th quadrant wastreated with root planing alone. 1 yearpost-treatment, the mean coronal re-growth of bone was found to be at alevel of 0.5 mm. The probing attach-ment gain ranged from 0.5 to 1,9 m.depending on the treatment modahty.

As can be concluded from previousstudies, the results regarding the pre-dictability of the healing outcome aftersurgical treatment of intraosseouslesions are contradictory.

The aim of the present study was tocompare clinically and radiographicallythe healing of infrabony defects treatedwith the gingivectomy (GV) with thehealing after modified Widman flap(MWF) technique.

498 Proestakis et at.

Table I. Experimental design

2 months Maintenance treatment

Seieclion Baseline Surgery 3 months 6 months

PUGIBOPPPDPALRadiographyPhotosDefect class.

Material and Methods

14 patients, 6 female and 8 tnales, 17-57years of age (tnean age 40 years) partici-pated in the study. The selection criteriawere: (a) uncomplicated tnedical his-tory; (b) at least 2 teeth with proximalinfrabony defects located bilaterally; thedefects should be revealed radiograph-ically; teeth with furcation involvementsor deep root furrows were excluded; (c)ability to follow regularly the recall ap-pointments.

The initiai treatment was performedby a dental hygienist 2 months priorto the surgical procedure. It comprisedinstructions in oral hygiene measuresand scaling of the entire dentition. Fol-lowing that, the patients returned for abasehne examination,

A total of 68 teeth exhibiting a defectsite with probing pocket depth > 5 mm2 months after scaling was selected forsurgical treatment. Each patient con-tributed to the study with between 2 and13 teeth located at 2 or 4 quadrants ofthe dentition,

A split-mouth design was applied,with 32 teeth randomly selected to betreated with the gingivectomy pro-cedure (GV) while 36 contralateral teethwere treated with a modified Widmannap (MWF) procedure,

Crinical examination

The experimental design is presented inTable 1,

At the baseline examination and atthe 3- and 6-month postoperative exam-inations, assessment of the periodontalstatus was performed by one observer(G,P,j in the following sequence:

(1) gingival conditions (gingivalindex, GI, Loe 1967);

(2) probing pocket depth, (PPD);(3) probing attachment level, (PAL);(4) bleeding on probing to the bottom

of the pocket, (BOP);

(5) oral hygiene status (plaque index,PH, Silness & Loe 1964),

Measurements were obtained at 4sites of each tooth: mesiobuccal, mid-buccal, distobuccal and mid-lingual.Probing was performed with a cali-brated periodontal probe (LL 20, HuFriedy, USA) to the nearest mm (diam-eter of the probe tip 0,5 mm, 1 mmincrements). The margin of a vacuumadapted soft acrylic onlay (0,7 mmthickness, Erkoien, Germany) was usedas fixed reference level for the PALmeasurements. For the proximal meas-urements, the probe was guided by theinterdental indentations of the splint as-suring a standardized angulation of theprobe towards the deepest part of thedefect.

To estimate the gingival recession, thedistance from the acrylic onlay marginto the gingival margin at the baselineexamination was compared with thesame distance at 3- and 6-months post-operatively.

Sources of errorIn order to assess the intra-examinermeasurement performance, repeatedmeasurements of the probing pocketdepths and probing attachment levelswere performed at the 3- or the 6-monthpostoperative examination in 60 teeth(240 surfaces). The measurements were

repeated with a 2-week interval betweenthe 1st and 2nd examination. Table 2presents the intra-examiner perform-ance.

Complete agreement was achieved in68,5% of the sites for the measurementsof PPD and in 63,8% for the PAL meas-urements. The measurements of FPDand PAL were reproduced within I mmin 96,8'yij and 95,4% of the sites, respec-tively. The standard deviation of theduplicate measurements was 0,667 mmand 0,723 mm for the PPD and thePAL, respectively,

Radiograpiiic examination

Conventional radiographyTo obtain a reproducible projection ge-ometry, a hard acrylic splint was madeon each individual plaster cast, A plasticfilm holder (Twix*, ASDI, Sweden),was attached with cold cured acrylicresin to the splint on the sites to beexamined. Care was taken to attach thefilm holder as parallel as possible to thetooth under examination, E-speed filmNo, 0 (Ektaspeed, Kodak, Rochester,USA) was used. As X-ray source, a ce-phalostat with a focus-film distance of150 cm and an object-film distance of0,5-1,0 cm was utilized. Different angu-lations (15 ' ^5 ) in the horizontal planewere used, depending on the site to beexamined. The exposure parameterswere 100-120 mAs and 60 kV, The filmswere processed in an automatic pro-cessor (Diirr Periomat, Germany) witha processing time of 7 min. The conven-tional radiographs were mounted inpairs (Fig, l-3a, b), in opaque filmframes (Trollhatteplast, TroUhattan,Sweden),

Subtraction techniqueThe conventional radiographs wereconverted to video signals and digitizedby an 8-bit analog to digital converter

Table 2. Intra-examiner performance for duplicate measurements of probing pocket depth(PPD) and probmg attachment level (PAL) expressed in number of sites and in % of Jotalnumber of sites {A'=240 sites)

Difference(mm)

- 32

„ _ !

0

-n+2

Probing

no.

25

4216426

10

x + S,D,=

pocket depth

(%)

0,82,0

17,568,510,80,40

-0,125±0,667

Probing

no.

06

381533841

,£ + S,D,

attachment level

(%)

02,5

15,863,815,81,70,4

= -0,004±0,723

Surgical treatment of infrabony defects 499

Fig. I. Subtraction image (c) based on conventional radiographstaken at ba.ieline (a) and 6 months postoperatively (b) of a mandibu-lar 1st molar treated by GV. The distal site (arrow) was assessed bythe 2 observers to present gain of bone tissue.

(256 grey-levels), resulting in images of512 X 512 pixels corresponding to about3 x 3 cm- in the original image. Thebaseline radiographs were digitally sub-tracted according to Grondahl et al.(1983), from the subsequent radio-graphs obtained 6 months postopera-tively. Before the subtraction, a grey-level value of 128 was added to eachpixel of the subsequent image. There-fore, the resultant subtraction image re-ceived a background grey-level of 128.against which any differences betweenthe original radiographs showed up.Areas darker than the background cor-responded to areas with a loss of bonetissue, while those which appearedbrighter corresponded to areas withgain of bone tissue (Fig. 1), Figs, 2 and3 are examples of resultant subtractiotiimages demonstrating loss and un-changed appearance of botie tisstie, re-spectively.

The bone tissue of each site was classi-fied into 1 of the 3 categories: gain (Fig,1), continued loss (Fig, 2) or unchangedappearance of the bone (Fig. 3),

The conventional radiographs fromthe baseline examinatioti were compared

with those taken 6 months postopera-tively for an analysis of both the distal,mesial and the buccalingual sites. Thesubtraction images were interpreted di-rectly as presented on the TV screen. Theconventional radiographs and the sub-traction images were first independentlyand separately assessed by 2 oral radiol-ogists (BK and KG), Then, each exam-iner ititerpreted the bone tissue with ac-cess to both the conventional and thesubtraction images. For the final evalu-ation of the bone tissue, all infortnationfrom the conventional and the subtrac-tion images was evaluated by both ob-servers together until they came tc anagreement. The inter-observer agree-ment for the 2 observers is expressed asoverall agreement and as Cohen's Kindex (Nuttall & McPaul 1985).

Surgrcal procedures

Gingivectonty procedureThe gingivectomy operations in thesame patient were carried out by 1 of 2operators (GS and RA). according tothe basic principles described by Gold-man (1946, 1951), The excision of thesoft tissues was performed in 2 stages.Firstly, after marking the base of the

pockets buccaliy and lingually the sup-racrestal portion of the soft tissuepocket was removed by an externallybevelled incision. The incision was end-ed just above the bone crest in such away that part of the buccal and lingualsoft tissue was also excised. In patientswith a shallow palatal vault, minimalbevelling was performed in order notto produce an extended wound surface.Secondly, the inner contents of the bonypocket were removed using a scaier ora heavy surgical curette until the botiywalls covering the defects were felt. Allgranulation tissue was removed. Thedepth of the defect was measured witha calibrated periodontal probe, 2 teethwith defects shallower than 2 mm and1 tooth with furcation involvement wereexcluded. The infrabony defects wereclassified according to the number ofos,seous walls surrounding the defects(Goldman & Cohen 1958), All root sur-faces were scaled and planed smoothwith ultrasonic and hand instruments.Bone removal was not performed. Thewound was irrigated with sterile saline,Periodontal pack (Coe pack", COELab,, Inc, Chicago, USA) was applied,first interdentally into the bone defectsand then buccally and lingually.

500 Proestakis et ai.

Fig. 2. Subtraction image (c) based on conventional radiographstaken at haselitie (a) and 6-months postoperalively (b) of the man-dibular premolars treated by MWF. The distal sites (arrows! wereassessed by the 2 observers to present contitiued loss of bone tissue.

The patients returned for pack re-moval after ! week. Pack reappiicationwas performed weekly for a minimumof 2 weeks.

Modified Widman flap procedureThe MWF operations were peformedby another operator (GB) according tothe principles described by Ramfjord &Nissle (1974). During the initial in-cision, care was taken to preserve asmuch as possible of the interdentaltissue. Mucoperiosteal flaps v/ere elev-ated 3-5 mm apically to the alveolarcrest. After the granulation tissue wasremoved from the defects, the samemeasurements were taken as those dur-ing the gingivectomy operations. 1tooth presented furcation involvementand was excluded from further evalu-ation. The root surfaces were scaled androot planed. Osteoplasty was not per-formed in any case. The flaps were re-placed at or near to their presurgicalpositions and sutured with interruptedsutures. Periodontal pack was not ap-plied. Sutures were removed 7-10 daysafter surgery.

Maintenance care

All patients, except 1. were instructedto rinse. 2 x daily, for a period of 4weeks postoperativeiy with 0.2% solu-tion of chlorhexidine digluconate (Hibi-tane«. ICl, Great Britain).

The patients were followed on aweekly basis during the 1st postopera-tive month. For the rest of the healingperiod, they were maintained on aplaque control programme which in-cluded oral hygiene reinforcement andprofessional tooth cleaning every 3-4weeks. Subgingival scaling was not per-formed at any of the recall appoint-ments.

Statistical analysis

Changes in plaque and gingiva) scoreswere analyzed with the /" test. The Wil-coxon signed rank test was used to ana-lyze the bleeding scores and the softtissue changes between treatments at thedifferent examinations, as well as toanalyze the effect of each treatmentfrom the baseline. The patient was

chosen as the computational unit. Thehypothesis of equal treatment effectswas rejected at the 0.05 level of signifi-cance. In addition, the 95'K. non-para-metric confidence interval for the differ-ences was calculated.

ResultsPiaque index

A statistically significant improvementm the oral hygiene status occurred dur-ing the postoperative period for bothtreatment modalities (^< 0.001). At thebaseline examination, only 17-21% ofall sites of the experimental teeth werefree of plaque (PlI 0). The plaque-freesites increased to 48-52% at the 3-month examination and to 52-54°/i> atthe 6-month postoperative examination(Fig. 4a). No differences were found inthe distribution of plaque indices of thetooth sites (interproximal and defect)treated with GV and MWF at any ofthe time intervals (/'>0.10).

Gingival index

At the baseline examination, none ofthe sites in the GV or MWF groups

Surgica! treatmeni of infrabony defects 501

Fig, 3. Subtraction image (c) based on convenliona! radiographslaken at hasvline (a) and 6 months post ope rative]y (b) of a mandibu-lar lsi molar treated with MWF The distal sile (arrow) was assessedby the 2 observers lo present unchanged appearance of bone tissue.

PLAQUE INDEXAtL SITES INTERPBOXIMAL SrTES

BL 3M

DEFECT SITES

>BL 3M I

GV MWF CSV MWF GV MWF

GlNGiVAL INDEXALL SITES

3M 6M

QV MWF QV tJMF

INTERPROXIMAL SITES

3K/I

DEFECT SITES

3M 6M

ao

OV MWF GV MV»F GV

Q G I O

OGII

GV tMfF SV MWF GV MWF QV MVWF GV MWF GV MWF

BFig. 4, % distribution of plaque index (Fig. 4a) and gingival index (Fig, 4b) scores at theliaseline exatnination and the exatninations 3 and 5 months postoperatively, for the differentsite categories treated with gingivectomy (GV) or n^odified Widman flap (MWF).

exhibited dinically healthy gingiva (GI0). At the 3-month postoperative exam-ination, the";. of inflamtnation-free gin-givai units was 46^9°/ij, and 6 monthspostoperatively, this was further in-creased to 54-59'/ii for the GV andMWF groups, respectively (Fig. 4b),Only 6-10% of the sites exhibited GI 26 months after the treatment com-pletion. The improvement in the gin-gival status was, for both treatments,statistically significant compared tobaseline (/><0.001). When the distri-bution of the GI scores was analyzedseparately for the interproximal and thedefect sites, it was shown that the defectsites exhibited a smaller "/« (n-AS'Yo)of inflammation-free sites. While astatistically significant improvement(/><0.001) for the GI scores was shownwithin treatments for each of the sitecategories examined, the differences be-tween treatments were not significant

Bleeding on probing

During the maintenance period, amarked reduction in the % of sites with

502 Proestakis et al.

BIDDING ON PROBING

ALL SITES INTEHPROXIMAL STTES DEFECT srres

BASEUNE 3 MOHTHS 8 MDKTHS BASELINE 3 MOMTHS B MONTHS3 MONTHS « MONTHS

Fig 5. % dislribulion of individual mean bleeding on probing (BOP) scores at the baseiineexaminalion and the examinations 3 and 6 months postoperatively for the different sitecategories treated with GV or MWF.

bleeding on probing occurred, from64-53% at the baseline examination to23-29% at the 3-nionth examination,and to 12-21% at the examination 6months postoperatively (Fig. 5). The re-duction in the bleeding scores was statis-tically significant ( / J < 0 . 0 1 ) for bothgroups. Analysis of the pooled dataconcerning the bleeding tendencyshowed that the MWF group had. 6months postoperatively, significantlyfewer ( / J < 0 . 0 5 ) sites that bled on prob-ing than the GV group (;)<0.05). Theresults of the site-specific analysisshowed that greater reduction in theBOP scores could also be seen duringthe postoperative period in the inter-proximal sites of the MWF group

Probing pocket depths

When all tooth sites were examined, amean of 1.50 mm reduction in PPD oc-curred during the postoperative period(Fig. 6a). The reduction was the samefor both treatment modalities and stat-istically significant cotiipared to the

baseline values (p < 0.001). The separateanalysis of the restilts for each site cat-egory showed that the largest reductionin PPD occurred in the sites exhibitinginfrabony defects (Fig. 6b). The initialPPD values or 6.35 mm for the GVgroup and 6.40 mm for the MWF groupwere reduced by 3.00 mm and 2.60 mm.respectively, at the 3-month examin-ation. This reduction was statisticallysignificant (jP< 0.001) compared tobaseline for both groups. Minor alter-ations m the PPD occurred between the3- and 6-month postoperative examin-ations. For the interproximal sites, sig-nificant reduction was shown amount-ing to between 2,36 mm for the sitestreated with GV and 2.10 mm for thosetreated with MWF (Fig. 6c). The com-parison between the GV and MWFgroups showed that in none of the sitecategories did a significant difference inthe amount of PPD reduction exist. Fig.7 presents the % distribution of PPDfor the defect sites at the different exam-ination intervals. In the GV group, 21(65%) of the infrabony pockets were 4-6mm deep and 11 (35%) > 6 mm deep at

PROBING POCKET DEPTHS

ALL SITESman (mil

DEFECT SITES INTERPROXIMAL SITES

the baseline examination. The corre-sponding numbers were 21 (58%) and15 {42-y«) for the MWF group, 3 monthsafter treatment, none of the sites in theGV group was deeper than 6 mm,whereas only 9 (28%) of the remainingpockets were in the 4-6 mm category.The same distribution was noted for the6-month examination. 3 months aftertreatment, none of the MWF sites wasdeeper than 6 mm. The prevalence ofmoderately deep sites dropped to 47%.At the 6 months re-examination, only 1surface was > 6 mm deep, whereas thesites at the 4-6 mm category wereftjrther reduced to 14 (39%).

Probing attachment levels

A small but significant (p<0.05) gainof probing attachment was noted post-surgically when all sites of the GV andMWF groups are analyzed (Fig. 8a).The amount of attachment gain was0.44 mm and 0.36 mm (3 months post-operatively). and 0,36 and 0.50 mm atthe 6-month examination for the GVand MWF groups, respectively. The de-fect sites of both groups showed a meangain of probing attachment at the levelof 1.22 mm to 1,35 mm 6 months post-operatively (Fig. gb). This gain was stat-istically significant compared to base-line (/7<0.01). The differences betweenthe groups, however, were not statisti-cally significant (/)>0.05). A smallergain was recorded for the interproximalsites (Fig. 8c) compared to the defectsites. This gain, though, was significantat every examination compared to base-line for both treatment groups

Fig. 6. Individual mean probing pocket depths at the baseline examination and the examin-ations 3 and 6 months postoperatively for the different site categories treated with GV orMWF

Fig. 9 presents the % distribution ofdifferent classes of PAL change for thedefect sites, 10 (3r/o) of the sites sub-jected to GV and 14 (39%) of the totaldefect sites subjected to MWF gained2 mm or more of probing attachmentcompared to baseline. Of the defect sitesin both groups. 30-40% gained 1 mmof probing attachment. Only 2 (6%) and1 (3%,) of the sites treated with GV andMWF, re.spectively, displayed loss ofprobing attachment 6 months post-operatively. This loss never exceeded 2mm.

When the changes in PAL were ana-lyzed according to the initial PPD ofthe sites (Fig. 10), a significant loss ofprobing attachment occurred for thesites initially 1-3 mm deep (/)<0.05).For the moderately deep sites of bothtreatment groups, a significant

Surgical treatment of infrabony defects 503

PERCENTAGE DISTRIBUTION OF PPD

DEFECT SITES

GVBL

MWFBL

^ 1 - 3 mm

GV3M GV GMMWF3M MWF6M

i'vi 4-6 mm

Fig 7. % distribution of probing pocket depth categories at the baseline examination and theexaminations 3 and 6 months postoperatively for the defect sites treated with GV or MWF,

PAL CHANGES

ALL SITES

mean (mm)

DEFECT SrTES

mean (min)

INTERPFIOXIMAL SfTES

mean (mm)

3 MONTHS 6 MONTHS

Ea MWF

3 MONTHS 6 MONTHS 3 MONTHS 6 MONTHS

S GV & MWF S GV Q MWF

Fig. H. Individual mean probing attachment level changes compared !o baseline for thedifferent site categories treated with GV or MWF.

PERCENTAGE DISTRIBUTION OF PAL CHANGES

DEFECT SITES

100

80

ao

40

20

QV3M>- 2 mm

MWF3M

S? 1 mm ^ 0 mmMWF6M

; <- -1 min

Fig. 9 % distribution of probing attachment level changes at the 3 and 6 months postoperativeexaminations compared to baseline for the defect sites treated with GV or MWF,

(/'<0,05) gain of attachment could beobserved (0,78 mm for the GV and 0,55mm for the MWF) 6 months postopera-tively. The largest gain of attachmentoccurred, for both treatment groups, atthe initially deeper site category ( > 6mm); the GV treated sites gained onthe average 1,90 mm while the MWFtreated sites gained 2,00 mm comparedto baseline (p<0,05 for both treat-ments).

Gingival recession

Similar and statistically significant(p< 0,001) amounts of gmgival re-cession, compared to baseline, werefound at the tooth surfaces of eachgroup at both postoperative examin-ations, 3 months postoperatively, theamount of gingival recession was 1,15mm for both groups (Fig, 1 la). For therest of the study period, only minor

changes were seen. Smaller amounts ofrecession were calculated, 6 monthspostoperatively, for the interproximalsites (1,33 mm and 1,49 mm for the GVand MWF, respectively) compared tothe defect sites; the GV procedure re-sulted in an average 1,92 mm of rootexposure in contrast to the 1,57 mm ofthe MWF (Ftg, l ib , c). The amount ofgingival recession on the defect surfaceswas signiftcant for both procedurescompared to baseline (p<0,01), but thedifference between the procedures wasnot statistically significant (/)>0,05),The % distribution of the changes inrecession for the defect sites comparedto baseiine is presented in Fig, 12, TheGV had 66% of the sites tn the 2-3mm level compared to the MWF 61% 3months postoperatively. Similar pat-terns of changes in recession was notedfor both groups 6 months postopera-tively,

Radiographic examination

The image quality of the radiographs of10 teeth precluded the assessment of thebone tissue. Therefore, the assessmentof the bone tissue was performed in 25teeth of the GV group (28 mfrabonydefects) and in 29 teeth of the MWFgroup (30 infrabony defects).

Table 3 presents the observer per-formance for all assessed sites. Theoveall inter-observer agreement and thecorresponding h: index values were 64%and 0,12 for the conventional radio-graphic technique, 78% and 0,50 for thesubtraction technique, and 86% and0,62 for the simultaneous interpretationof both conventional and subtractionimages. The overall inter-observeragreement for the assessment of the de-fect sites was, however, lower than theagreement for all sites. For the conven-tional radiographic technique, the over-all agreement for the defect sites was38%, for the subtraction technique 69%and for the simultaneous interpretationsof both conventional and subtractiontechnique, 80%,

The simultaneous interpretation ofconventional and subtraction images ofthe defect sites by both observers is pre-sented in Table 4, 7 (25%) of the defectstreated with GV gained bone tissue (Fig,I) compared to 9 (30%) treated withMWF, 1 defect of the GV group and 5of the MWF group lost bone tissue dur-ing the 6 months period (Fig, 2), In theremaining defect sites of both groups,the appearance of the bone tissue was

504 Proestakis et al.

PALCHANGES

ALL SITES

GINGIVECTOMY

PAL CHANGES

ALL SITES

MODIFIED WIDMAN FLAP

3 MONTHS 6 MONTHS

1-3 mm O 4-6 mm Q > 6 mm

3 MONTHS 6 MONTHS

1-3 mm B 4-G mm Q > e mm

Fig. JO. Individual mean probing attachment level changes compared to ba.^eline accordingto the initial PPD of all sites treated with GV or MWF,

GINGIVAL RECESSION

ALL SITES

iTwan (inin)

2,5

2

1,5

1

0,50

3 MONTHS 6 MONTHSS QV S MWF

DEFECT SITES

Riaan (mm)

2,5

2

1,5

1

0,5

03 MONTHS 6 MONTHS

S GV B MWF

1iINTCRPROXIfcML SITES

mean (mm)

2,5

3 MONTTHS 6 MONTKS

S GV @ MWF

Fig. I!. Individual mean changes in gingival recession compared to baseline for the differentsite categories treated with GV or MWF,

PERCENTAGE DISTRIBLmC»J OF RECESSION CHANGES

DEFECT SITES

GV3M UWF3U GVSUE 0 / 1 mm fS 2 / 3 mm » > 3 mm

Fig. 12. % distribution of changes in gingival recession at the 3 and 6 months postoperativeexaminations compared to baseline for the defect sites treated with GV or MWF,

Table S. Overall inter-observer performance for 2 observers assessing conventional radio-graphs, subtraction images and conventional and subtraction images together: numbers ofsites on which the 2 observers were unanimous or disagreed in their assessments

Imaging Technique

conventional radiographysubtraction techniqueconventional and subtraction

Unanimousdecision

87112123

No, sites

Disagreement

1 step 2 steps

46 430 121 0

Total

137143144

judged as unchanged (Fig, 3), Frotn theother interproximal sites in each group.i,e,. all interproximal sites besides thosewith irtfrabony defects. 1 site in the GVgroup and 2 in the MWF group showedgain of bone tissue, 3 of the sites treatedwith GV and 6 treated with MWF pre-sented continued bone loss. Analysis ofthe bone changes for the bucco-lingualsites revealed that I site in each surgicalgroup showed gain, and 1 more loss ofbone tissue. The majority of these sitesremained unchanged.

Variations were seen in the individualbone tissue changes. Thus, 1 of the sub-jects accounted for 25V(, of the defectsites, showing gain of bone, whereas 4of the 14 subjects had 50% o( the siteswith bone gain. On the other hand. 1 ofthe participants is responsible for 50%of the sites showing continumg loss ofbone tissue. When the changes m bonetissue were analyzed tn accordance withthe number of defects walls (Table 4).no relation could be found {/- = 11,162.

Table 5 compares the changes in PALand the bone changes between the base-Une and the 6 months postoperativeexamination, 19% of the sites thatgained bone tissue also showed gain inPAL > 2 tnm, compared to only 3%of the sites in the group that showedunchanged appearance of the bonetissue. Furthermore, none of the sitesthat gained bone tissue lost probingattachment 6 months postoperatively.However, no statistically significant as-sociation was shown between bone andPAL changes (/-= 8,599, /)>0,05),

Discussion

The present study has shown that therewas no significant difference in the heal-ing response in infrabony pockets be-tween the 2 treatment modalities, norwas there any difference when alltreated sites were induced. This is inaccordance with Zamet (1967), Roslinget al, (1976b), Westfelt et al, (1985) andLindhe et aL (1987), In the study byRosling et a!, (1976b). however, theattachment level changes of approximalsurfaces treated with the GV techniquewere evaluated. They found a loss ofattachment with a mean of 0,4 mm. Thisis in contrast to the present study, whereGV in approximal surfaces resulted ina gain of attachment (mean 0.93 mm).One reason for the differences betweenthe 2 studies might be that in our study,

Surgical treatment of infrabony defects 505

Table 4. Radiographic bone tissue changes 6 months postoperatively compared to baseline asrelated to the defect type and the surgical modality

GVBone tissue

MWFBone tissue

Defect type

1 wall1+2 walls2 walls3 + 2 walls3 walls

loss

00100

unchanged

00767

gain

00i33

loss

10112

unchanged

03

101

gain

!023•?

total 20 16

only teeth presenting infrabony defectswere included.

Pocket reduction was achieved by acombination of gingival recession andgain in probing attachment. Pockets as-sociated with infrabony defects gainedon average 1,35 mm of probing attach-ment after treatment with MWF, whilean average of 1,60 mm of gingival re-cession was calculated. The amount ofprobing attachment gain is somewhatmore than that obtained by Isidor et al,(1985) and Becker et al, (1988), but lessthan in the studies by Rosling et al,(1976a), Froum et al, (1982) and Beckeret al, (1986), The levet of attachmentgain though, is consistent with Renvertet ai, (1981), Renvert & Egelberg (1981),Westfelt et al, (1985), Lindhe et al,(1987), In the study by Isidor et al,(1985), a gain of probing attachment of0,5-0,9 mm was obtained after treat-ment of infrabony defects, while theamount of gingival recession in thosesites was 2,6-3,4 mm, Froum et al,(1982) reported a mean 1,4 mm of PALgain and 2,0 mm of gingival recessionin infrabony pockets treated with opendebridement procedures, and Renvert &Egelberg (1981) achieved 1,20 mm ofprobing attachment gain and 1,60 mmof recession. In the studies by Rosiinget al, (i976a), a high standard of oralhygiene was maintained during the en-

Tabk 5. Association between radiographicbone tissue and probing attachment levelchanges 6 months postoperatively comparedto baseiine for Ihe defect sites (A' = 58): num-ber (Vn) of sites within each bone tissuechange category and the correspondingchanges in probing attachment level

Bonetissue

gainunchangedloss

Probing attachment

< - lmm

011

(0)(3)(17)

0

271

mm

(12)(19)(17)

1-2

11274

level

mm > 2

(69)(75)(66)

310

mm

(19)(3)(0)

tire postoperative period, A gain ofattachment amounting to 3 mm wasachieved for the interproximal sitestreated with MWF, Variations in the pa-tient and defect selection, preoperativeprobing pocket and defect depths andoral hygiene levels may account forthese differences.

The attachment level changes suggestthat the alterations are related to theinitial PPD of the sites. Shallow (1-3tnm) pockets tend to lose probingattachment, whereas deeper pocketsseem to gain. The biggest gam occurredin initially deeper pockets. This obser-vation corroborates the results fromsimilar studies (Rosling et al, 1976b,Hill et ai, 1981, Pihlstrom et al, 1981.Lindhe, et al, 1982a, b, Westfelt et al,1985, Lindhe et al, 1987. Becker et ai,1988), It should be noted, however, thatwhile attachment loss at initially shai-lower sites mainly represents a true iossof connective tissue attachment, thegain of attachment seen in deeperpockets is due to tlie relative resistanceof the healthy periodontal tissues to api-cal probe penetration (Armitage et al,1977, Robinson & Vitek 1979. Van derVelden 1979, Listgarten 1980),

The degree of gingival recession wassimilar at all site categories for the twotreatment modalities (Fig, 11), Whenthe changes were analyzed separatelyfor the defect sites (Fig, 12), no differ-ences could be seen in the distributionof different degrees of root exposure be-tween the procedures. These fmdingsare in accordance with those of Lindheet al, (1987), These authors studied thepost-surgical alterations of the perio-donta] tissues utilizing, besides GV, 5treatment modalities. They concludedthat irrespective of the treatment mo-dality, heaiing is likely to produce simi-lar degree of root exposure.

It was suggested that gingivectomyresults in uneven gingival contour (Za-met 1967), This condition might have

posed an obstacle in the efftcacy of theoral hygiene measures. In the presentstudy, however, no differences in Pll andGi were observed between the sitestreated with GV or MWF A significantimprovement in the plaque and gingivaiindex scores occurred during the main-tenance period for both treatment mo-dalities. It must be noted that this im-provement would have been more dis-tinct if the comparisons had been madewith the pre-hygiene plaque scores.

Substantial reduction in the sites thatbled on probing was observed duringthe post-surgical examinations for bothtreatments, ,A large number of inter-proximal and defect sites though,treated with GV, were still bleeding 6months after treatment. For the defectsites, however, the difference in thebleeding tendency was not statisticallysignificant. No apparent explanationcan be given for that phenomenon, sincethe prevalence of plaque and the gin-gival index scores of these sites do notverify a plaque induced inflammatoryresponse. It is possible that lateral probepenetration into the connective tissue(Spray et al, 1978) or disruption of thevessels can be responsible for this reac-tion,

A 6-month period was chosen for theevaiuation of the treamtent outcome,since previous studies have shown thatthe major part of the soft tissue changeswere completed within 6 months follow-ing treatment (Rosling et al, 1976a, b,Lindhe et al, i982a, Lindhe & Nymani985, Westfelt et al, 1985, Lmdhe'et al,i987).

In the present study, bone changeswere evaluated in both conventionairadiographs and subtraction images.The subtraction technique has beenproven to be a sensitive and accuratemethod in evaluating alveolar bonechanges (Grondahl & Grondah! 1983.Grondahl et al, 1983, Hausmann et al,1985, Schmidt et al, 1988), It should benoted that the possibility to detectchanges in the subtraction images is veryciosely dependent on the level of stan-dardization between the 2 radiographsavailable for the subtraction techniqueand the accuracy of their alignment(Grondahl et al, 1984, Janssen et al,1989), In order to overcome the problemof geometric misalignment of some ofthe images, a simultaneous interpreta-tion of both conventional and subtrac-tion images was applied. As the resultsof overall agreement and K index valuesindicate, higher agreement rates were ac-

506 Proestakis et al.

complished when the subtraction tech-nique was employed and even betterwhen the simultaneous interpretationwas applied. Similar values to thesefound in the present study were demon-strated by Grondahl et al. (1987).

In order to obtain a reproducible pro-jection geometry of the radiographic im-ages, a cephalostat was utilized. In astudy by Jeffcoat et al. (1987). it is statedthat the use of a cephalostat for a repro-ducible patient positioning can giveeven better results than when a stentcoupled to an X-ray tube is used. Withthe cephalostat technique, the relation-ship between the X-ray beam and theobject can stay nearly identical and thelong focus-film distance results in a uni-form magnification, minimizing distor-tion. However, the experiments byJeffcoat were carried out with strictlylateral projections and only with bite-wing films. In the present study, whenapplying the cephalometric techniquetogether with a stent and not only inlateral regions, equally good resultscould not be achieved. One possible ex-planation could be the selection of pa-tients in the present study. Some of themhad such advanced bone loss that bite-wing radiographs could not be used.Periapical radiographs introducing ahigher risk for differences in film place-ment and consequently projection dif-ferences had to be used. Because theteeth were used to secure film place-ment, changes in their position over the6-month period may have caused geo-metric differences between the radio-graphs.

Thus, the results indicate that in or-der to use the cephalometric techniquefor oblique projections, a more rigidplacement of the patient with some kindof exact registration of the position atthe baseline examination is necessary.

Of the infrabony defects treated. 16(28%) showed gain and only 6 (10%)showed continued ioss of bone tissueduring the 6 months postoperativeperiod for both treatment modalities.The variance in the bone changes is inaccordance with the results of thestudies by Renvert & Egelberg (1981),Renvert et al. (1985a). Froum et al.(1982), Isidor et al. (1985). In thosestudies, bone changes after flap pro-cedures were assessed by re-entry meas-urements (Froum et al. 1982), transgin-givai bone level measurements(Renvert & Egelberg 1981, Renvert etal. 1985a, b) or assessment of alveolarbone height on standardized radio-

graphs (Isidor et al. 1985). Limitedamounts of bone gain (0.5-1.2 mm)were obtained and the degree of bonefill varied within the defects studied. Incontrast Rosling et al. (1976a, b) andPoison & Heijl (1978) reported bonegain in nearly all defects treated,amounting 70°4.-80% of the initial de-fect depth. Moreover, in the study byRosling et al. (1976b). 9 out of the 39defects treated with gingivectomy ex-perienced loss of bone tissue (mean 0.7mm) postsurgically. it is possible thatvariations in the level of post-surgicalplaque control, depth of the defectsstudied and the method of evaluationmay account for the differences. In thestudies by Rosling et al. (1976a. b). theassessment of the alveolar bone heightwas performed by measurements onstandardized radiographs. Radio-graphic measurements, though, are theleast accurate way of estimating changesof alveolar bone height (Renverl et al.1981, Benn 1990).

Studies of bone regeneration in infra-bony defects suggested that 3-wall de-fects have a higher osieogenic potentialthan the 2- or 1-wall defects (Prichard1957, Patur & Giickman 1962. Elle-gaard & Loe 1971). In the present study,no such relation was found (Table 4).This observation is in accordance withRosling et al. (1976a. b). Poison & HeijI(19781. Renvert et al. (1985b). Further-more, according to Renvert et al.(1985b). a high degree of correlationexists between the depth of the bonydefect and the postoperative changes inbone levels (p < 0.01). Even though stan-dardized defect measurements were notobtained in the present study, it wasobserved that the defects that gainedbone tissue were more than 4 mm deep.Moreover, there was no association be-tween the bone tissue and the probingattachment level changes 6-monthspostoperatively. This observation is inagreement with Payot et al. (1987) andBragger et al. (1988).

It seems resonable to conclude fromthe present study that both treatmentmodalities would induce the same de-gree of soft and hard tissue changes ininfrabony defects. This means that GVand MWF would both induce gain ofprobing attachment and possibly bonegain 6 months postoperativeiy.

Acknowledgements

Sincere thanks are due to Siv Jacobsonfor ora! hygiene treatment and to Mika-

e! Astrom for help with the statisticalanalysis.

Zusammenfassung

Gingivektomie oder Luppenchirurgie: Der Er-folg hei der Behandlung intraussoser DefekieDas Ziel der vorliegenden Studie war, Kurz-zeitresuliate nach der Behandlung iniraossa-rer Defek'te mil Gingivektomie (GV), mit Be-handlungsresultaten nach der modifiziertenWidman'schen Lappenoperation (MWF =modified Widman flap) zu vergleichen. Fiirdiese Untersuchung wurden 14 Patienten mit68 bilaieralen. intraossaren Defekten ausge-wahh. AnlaBlich der Eingangsuntersuchungund postopcrativer Untersuchungen nacb 3und 6 Monaten wurde die Mundpflege, derZustand der Gingiva. die Zahnneischblutungnach dem Sondieren, die sondierte Taschen-tiefe und das sondierle Atiachmenlniveau be-urleill und regi.slrieri. Konventionelle Ronl-genaufnahmen mit reproduzierbarer Projek-tionsgeometrie wurden angefertigt. lmRahmen des Versuchsansatzes nach demsplit-mouth Model! wurde ein Kieferqua-drani zufalJig mil der G\\ und der kontraJale-rale mit der MWF-Operation hehandeit. Ver-anderungen der Knochengewebe wurden milHilfe von konventioneSSen und Subtraktions-Rontgenbildern von 2 Untersuchenden be-gutbachcet. Ausserdem wurde die ijbererein-slimmung zwischen den Resultaten der kon-ventionellen und der Subtraktionstechnik un-tersucht. An den meisten Stellen hatten sichdie gingivalen Verhalinisse erheblich verbes-sert und die Zahnfleischblutung nach demSondieren war geringer. Bei beiden Behand-lungsformen waren die Sondierungsliefen umetwa y mm geringer und der sondierte At-tachmentgewinn behef sich auf 1.22-1.35mm. Bei der GV war die Rezession der Gingi-va (1.90 mm) ein wenig hoher als bei der.MWF (].6O mm). Die Rontenuntersuchungzeigte. dafi nach der GV ein Knochengewinnan 7 Defekten und nach der MWF an 9 De-feklen vorlag. Diese Untersuchungen zeigen.dafi mit intraossdsen Defekten verbundeneTaschen mit beiden Behandlungsformenerfolgreich behandeit werden konnen undweiterhin, daB Knochengewinn als Behand-lungsfolge vorkommen. aber nicht vorausge-sagt werden kann.

Effet du irailemeni des IHiotts infraosseusespar gingivectomie ou operation a lambeau. Uneetude clinique ei radiographique14 patients avec 68 lesions infraosseu&es bila-terales ont ete selectionnes. Lors de I'exameniniiial ainsi que 3 el 6 moi.s apres Toperationles indices cliniques suivanls ont ete mesures:hygiene buccale, condition gingivale. saigne-ment au sondage, profondeur de poche ausondage et niveau d'attache. Des radiogra-phies conventioneJIes reproductibles ont eteoblenues. Un quadrant a ete Iraite par gingi-vectomie el le contralateral par operation de

Surgical treatment of infrabony defects SCSI

Widman modifiee. Les variations de tissu os-seux ont ete mesurees a l'aide d'imagesconventionelles et de soustraction par deuxobservateurs. La variation interobservateurdes techniques conventionelle et de soustrac-tion a egalement ete etudiee. La majorite dessites out montre une amelioration des condi-tions ging]vales et une reduction du saigne-ment. Pour ies 2 types de traitement les pro-fondeurs au sondage ont ete reduites d'unemoyenne de 3 mm tandis qu'un gain d'atta-che moyen de 1.22 a ! ,35 mm a ete obtenu.La gingivectomie etait suivie d'un peu plusde recession gingivale (1.90 mm) que I'opera-tion a lambeau (1.60 mm). L'analyse radio-graphique a mis en evidence un gain osseuxdans sept lesions traitees par gingivectomieet 9 lesions soignees par operation a iambeau.Les poches associees aux lesions infraosseu-ses peuvent done etre traitees avec succes parles 2 types d'operation. De plus, un gain os-seux peut survenir apres traitement mais demaniere imprevisible.

References

Armitage, G. C . Svanberg, G. K. & Loe, H.(1977) Microscopic evaluation of clinicalmeasurements of connective tissue attach-ment. Journal of Ciinical Periodonloiogy 4,173-190.

Becker. W., Becker, B. & Berg, L. (1%8) Re-pair ofinfrabony defects as a result of opendebridement procedures. Report of 36treated cases. The Internalional Journal ofPeriodontics and Restorative Dentistrx 6,9-20.

Becker, W., Becker, B., Ochsenbein, C . Ker-ry, G., Caffesse. R., Morrison, E. & Prich-ard. J. (1988) A longitudinal study com-paring scaling, osseous surgery and modi-fied Widman procedures. Results after oneyear. Journal of Periodontologv 59,351-365.

Benn, D. K. (1990) A review of the reliabilityof radiographic measurements in estimat-ing alveolar bone changes. Journal of Clini-cal Periodontology 17, 14-21.

Bragger, U., Pasquali, L. & Kornman, K. S.(I98S) Remodelling of interdental alveolarbone after periodontal flap procedures as-sessed by means of computer-assisted den-sitometric image analysis (CADIA). Jour-nal of Clinical Periodontologv IS, 558-564.

Ellegaard. B. & Loe. H. (197!) New attach-ment of periodontal tissues after treatmentof infrabony lesions. Journal of Perio-dontology 42, 648-652.

Froum, S. ],, Coran, M., Thaller, B., Kush-ner, L., Scopp, I. W. & Stahl, S. S. (1982)Periodontal healing following open de-bridement flap procedures. I. Clinical as-sessment of soft tissue and osseous repair.Journal of Periodontology 53, 8-14.

Goldman, H. M. (1946) Gingivectomy: Indi-cations, contraindications and method.American Journal of Orthodontics 32,323-326.

Goldman, H. M. (1951) Gingivectomy. Oral

Surgery, Oral Medicine, Oral Pathology 4.1136-1157.

Goldman, H. M. & Cohen, D. W. (1958) Theinfrabony pocket: classification and treat-ment. Journal of Periodontology 29,272-291.

Grondahl, H-G. & Grondahl. K. (1983) Sub-traction radiography for the diagnosis ofalveolar bone lesions. Oral Surgery. OralMedicine, Oral Pathology 55, 208-213.

Grondahl, H-G.. Grondahl, K. & Webber,R. (1983) A digital subtraction techniquefor dental radiography. Oral Surgery. OralMedicine. Oral Pathology 55, 96-102.

Grondahl. K., Grondahl, H-G. & Webber,R. (1984) Influence of the variations ofprojection geometry in the detectability ofperiodontai bone lesions. A comparisonbetween subtraction radiography and con-ventional radiographic technique. Journalof Clinieal Periodontologv H , 411^20.

Grondahl, K., Grondahl. H-G.. Wennstrom,J. & Heijl, L. (1987) Examiner agreementin estimating changes in periodontal bonefrom conventional and subtraction radio-graphs. Journal of Clinical Periodontologv14. 74-79.

Hausmann, E., Christersson, L., Dunford,R., Wikesjo, U., Phyo, J. & Genco. R.(1985) Usefulness of subtraction radi-ography in the evaluation of periodontaltherapy. Journal of Periodontology(Supplement) 56, 4-7.

Hill. R. W., Ramfjord, S. P . Morrison, E. C ,Appleberrj. E. A., Caffesse. R. G.. Kerry.G. J. & Nissle, R. R. (1981) Four types ofperiodontal treatment compared over twoyears. Journal of Periodonlology 52.655-662.

Isidor. K. Attstrom. R. & Karring, T. (1985)Regeneration of aiveoiar bone followingsurgical and non surgical periodontaltreatment. Journal of Clinical Periodontol-ogy 12, 687-696.

Janssen. P. T. M., van Palenstein Helderman,W H. & van Aken, J. (1989) The effect ofin-vivo occurring errors in the reproducibi-lity of radiographs on the use of the sub-traction technique. Journal of ClinicalPeriodontologv 16, 53-58.

Jeffcoat, M. K,, Reddy. M. S., Webber, R.L., Williams, R. C. & Ruttimann, U. E.(i987) Extraoral control of geometry fordigital subtraction radiography. Journal ofPeriodontal Research 22. 396-402.

Lindhe, J.. Westfeit, E., Nyman, S., Socran-sky, S., Heijl, L. & Bratthall G. (1982a)Healing following surgical/non surgicaltreatment of periodontal disease. Journalof Clinical Periodon tology 9, 115-128.

Lindhe, J., Socransky, S. S., Nyman, S., Haf-fajee, A. & Westfelt, E. (1982b) "Criticalprobing depths" in periodontal therapy.Journal of Clinical Periodontologv 9.323-336.

Lindhe, J. & Nyman, S. (1985) Scaling andgranulation tissue removal in periodontaltherapy. Journal ofClinieal Periodontology12, 374-388.

Lindhe, J., Socransky, S. S., Nyman, S. &

Westfelt, E. (1987) Dimensional alterationsof the periodontal tissues following ther-apy. The International Journal of Perio-dontics and Restorative Dentistry 7, 9-21.

Listgarten, M. A. (1980) Periodontai prob-ing. What does it mean? Journal of ClinicalPeriodontology 7, 165-176.

Loe, H. (1967) The gingival index, the plaqueindex and the retention index system. Jour-nal of Periodontology 38, 610-616.

Nuttall, N. M. & McPaul, J. K. (1985) Theanalysis of inter-dentist agreement in cariesprevalence studies. Community DentalHealth 2, 123-128.

Ochsenbein. C. (1977) Current status of oss-eoys surgery. Journal of Periodontology 4li,577-586.

Patur, B. & Glickman, 1. (1962) Clinical androentgenographic evaluation of the post-treatment healing of infrabony defects.Journal of Periodontology 33, 87-iO2.

Payot, P . Bickel. M. & Cimasoni, G. (1987)Longitudinal quantitative radiodensitome-tric study of treated and untreated lowermolar furcation involvements. Journal ofClinical Periodontologv 14, 8-18.

Pihlstrom, B. L., Ortiz-Campos. C. &McHugh. R. B. (1981) A randomized fouryear clinical study of periodontal therapy.Journal of Periodontology 52, 227-242.

Poison, A. M. & Heijl, L. C. (1978) Osseousrepair in infrabony penodontal defects.Journal of CUnicai Periodontologv 5.13-23.

Prichard. J. (1957) The infrabony techniqueas a predictable procedure. Journal ofPeriodontology 28, 202-216.

Prichard, J. (1961} Gingivoplasty. Gingivec-tomy and Osseous surgery. Journal ofPeriodontoiogy 32, 275-282.

Ramfjord. S. & Nissle. R. (1974) The modi-fied Widman flap. Journal of Periodontolo-gy 45. 601-607.

Renvert. S.. Badersten. A., Nilveus, R. & Eg-elberg, J. (1981) Healing after treatment ofperiodontal intraosseous defects (I). Com-parative study of clinical methods. Journalof Clinical Periodontology 8. 387-399.

Renvert. S. &. Egeiberg. J. (1981) Healingafter treatment of periodontal intraosseousdefects, il . Effect of citric acid condition-ing on the root surface. Journal ofCliniealPeriodontology 8, 459^73.

Renvert, S., Garrett, S., Shallhorn, R. G. &Egelberg, J. (i985a) Healing after treat-ment of periodontal intraosseous defects.Hi. Effect of osseous grafting and citricacid conditioning. Journal of ClinicalPeriodontology 12. 441^55.

Renvert. S., Garrett, S., Nilveus, R.. Durwin,A., Chamberlain, H. & Egelberg, J.(1985b) Healing after treatment of perio-dontal intraosseous defects. Vi. Factors in-fluencing the liealing response. Journal ofClinical Periodontologv 12, 707-715.

Robinson. P J. & Vitek. R. M. (1979) Thereiationship between gingival inflam-mation and resistance to probe penetra-tion. Journal of Periodontal Research 14,239-243.

508 Proestakis et al.

Rosling. B,. Nyman. S. & Lindhe. J. (1976a)The effect of systematic plaque control onbone regeneration in infrabony pockets.Journal of Clinical Periodoniology 3.38-53.

Rosling. B.. Nyman. S. & Lindhe. J. (1976b)The healing poteniial of the periodonialtissues following different techniques ofperiodontal surgery in pSaque-free den-titions. Journal of Clinical Periodontologv3. 233-250.

Silness. J. & Loe. H. (1964) Periodontal dis-ease in pregnancy. II. Correlation betweenoral hygiene and periodontal condition.Acta Odontohgica Scandinavica 22.121-135.

Schmidt. E.. Webber. R.. Ruttimann. U. E. &Loesche, W. (1988) Effect ofperiodontaltherapy on alveolar bone as measured bysubtraction radiography. Journal of Perio-dontology 59, 633-538.

Spray. J. R.. Garnick. J. J.. Doles. L. R. &Klawitter. J. J. (1978) Microscopic demon-stration of the position of periodontalprobes. Journal of Periodontologv 49.148-152.

Van der Velden. U. (1979) Probing force andthe relationship of the probe tip to theperiodontal tissues. Journal of ClinicalPeriodontology b. 106-114.

Westfelt. E.. Bragd. L.. Socransky. S. S., Haf-fajee. A. D. . Nyman. S. & Lindhe. J.

(1985) Improved periodontal conditionsfollowing therapy. Journal of ClinicaiPeriodontohgy 12. 283-293.

Zamet. J. S. (1967) A comparison of unem-bellished gingivectomy with the inversebevel flap procedure incorporating osseousrecontouring. Dental Practitioner 17,387-395.

Address:

Gunilla BratthallDepartment of PeriodontologyFaculty of OdontologyCart Gustafs vdg 34S-2I4 21 MaimsSweden