Periadantalagy2000, Val. 11, 1996, 18-28Printed in Denmark All rights reserved

Copyright @ Munksgaard 1996

PERIODONTOLOGY 2000

ISSNO906-6713

DAVID A. GARBER & MAURICE A. SALAMA

.the teeth

.lip framework

.the gingival scaffold.

The teeth

The dentist is concerned with the color, the posi-tion, and the shape or silhouette form of teeth. Theadvent of adhesive dentistry has allowed literallyan instantaneous change in the color, the shapeand the position of teeth via bonding techniquessuch as porcelain laminate veneers and direct

composite bonding.

The gingival scaffold

The primary objective of periodontal therapy is torestore and maintain the health and integrity of theattachment apparatus. From an aesthetic perspec-tive this is often not enough. An irregular gingivalarrangement, despite being healthy, may strike adiscordant note, and it may become desirable toestablish a certain harmony and continuity of formto the free gingival margin. In its broadest sense,this would require that the gingival architecture forthe two central incisors mimic one another. For thelateral incisors, one would like to see these gingivalmargins somewhat more incisally placed and, forthe most part, bilaterally symmetrical. The cus-

I Table 1. Methods of developing gingival

harmony

Orthodontics

ExtrusionIntrusion

Until recently, dentists' and the public's concept ofdental aesthetics was necessarily limited to alter-ations of the teeth themselves. Dentists concernedthemselves with changing the position, the shapeand the color of the teeth -basically restoringmissing units or enhancing those already present.For the most part the dentist was forced to acceptthe pre-existing relationship between the threecomponents of the smile; the teeth, the gingivalscaffold and the lips.

Interestingly, the restorative dentist's concept ofaesthetics varied considerably from that practicedby removable prosthodontists where, in the fulldenture set-up, they could not only select the mostdesirable shape and color of denture toothconcomitant with the patient's facial features butcould position them in the optimal relationshipwith regards to the upper lip, the lower lip and thecommissures of the mouth -thereby creating thedesired ideal smile.

The three basic tenets germaine to optimalaesthetics in removable prosthetics were not reallya part of the restorative dentist's rules, as anychanges in the pre-existing lip-tooth-gingivalrelationships were thought to necessitate long-term orthodontic therapy, often in combinationwith orthognathic surgery or aggressiveperiodontal procedures. Today much of this haschanged; with the advent of soft tissue periodontalplastic procedures designed to enhancedentofacial harmony following the same basictenets as those of the removable prosthodontist.

The domain of periodontics has changed frombeing strictly a health service to one where smileenhancement has been brought to the forefront oftreatment planning.

The essentials of a smile involve therelationships between the three primary

components:

Surgery

Additive gingival techniques

Resective gingival techniques

To develop this symmetry, both surgical andorthodontic procedures might be used (Table I).

Surgical techniques

pids, in turn, would have the free gingival marginat the same level of the centrallncisors and match -

ing one another. Extending distally, the tissues onthe premolars would be somewhat coronally posi-tioned (1,9).

Periodontic plastic procedures, such as the basicgingivectomy, soft tissue grafting or the apicallypositioned flap, may be used to change thesilhouette form of teeth and their relative

proportion.

Additive techniques for augmenting gingiva haveevolved from the early free gingival grafts throughthe many different forms of contiguous grafting.This would include pedicle grafts, connective tis-

Fig. I. Preoperative view showing gingival recession of themaxillary left central incisor. This is the only apically no-tated gingival margin showing an overall lack of harmony.

Fig. 2. Postoperative view following semilunar graft dis-playing optimally developed gingival symmetryFig. 3. Postorthodontic case showing excessive display ofgingival tissue below the inferior border of the upper lip.This is a case of altered passive eruption, which should bedifferentiated from vertical maxillary excess. The short,rather squat teeth and hyperplastic tissue usually indicatean altered passive eruption case. Compare this with thepostoperative result in Fig. 5 where the gingiva line fallsjust below the inferior border of the upper lip.

Fig. 4. Periodontal probing showing the amount of tissuereadily removed without compromising the biologicalwidth. A basic gingivectomy/gingivoplasty is therefore theprocedure of choice.

Fig. 5. The case following a gingivectomy showing nor-mally proportioned teeth with a decrease in the amount ofgingival display just below the border of the upper lip.

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Garber & Salama

The medium lipline in western culture isdeemed to be the most attractive. When the patientsmiles, a nominal exposure of 1 to 3 mm of gingivafrom the most apical extent of the free gingivalmargin to the inferior border of the upper lip isexposed. Thus the teeth in their entirety are ondisplay as well as the interdental gingival tissueand the border of free gingiva around the cervicalarea of the tooth.

sue grafting, semilunar techniques, coronally posi-tioned grafts and guided tissue regeneration (Fig. 1,2) (2, 3, 5, 7, 8, 10, 11, 13, 14).

Resective techniques involve both the basicgingivectomy with or without gingivoplasty, as wellas the full flap procedure incorporating osseousremoval for crown lengthening of one or moreteeth (Fig. 3-5).

The geometry of harmony

Orthodontic techniques

The great advantage in moving teeth orthodonti-cally is that the entire attachment apparatus, in-corporating the osseous structure, periodontallig-aments and the soft tissue components, moves to-gether with the tooth. This means that, in health,during an extrusive movement, the free gingivalmargin will move coronally at the same distance asthe incisal edge moves (Fig. 6) .Concomitantly, theosseous level will move an identical distance in thesame direction.

From an aesthetic perspective, this means thatany intrusive or extrusive tooth movement can beused to develop symmetry of the gingival margin ina nonsurgical mode (Fig. 7-9). This is particularlyuseful when any form of restoration is necessary, asa surgical procedure invariably exposes rootstructure, where the mesiodistal dimension of thetooth is now considerably narrower (Fig. 10). Inattempting to restore this, it becomes necessary toprepare the tooth and the tissue in such a way thatan emergence profile can be developed from deepwithin the sulcus to avoid lateral horizontalextensions from the preparation line on thenarrower root surface to the desired wider form ofthe restoration. If there is a dramatic diminution ofthe mesiodistal width of the root at the originalgingival level versus the desired level, thenorthodontics may be the treatment of choice.

The lips

Within the confines of th~ lipline, the remainingtwo components of the smile need to be arrangedin such a way as to develop a c~rtain continuity ofform, harmony and balance (Fig. 11). Classically,the prosthodontist would like to set up a dentureso that the level of the gingival margins of the max-illary teeth parallel the form of the upper lip. Theincisal edges of these maxillary teeth tend to followthe form of the lower lip. In a transverse dimen-sion, the teeth should extend progressively posteri-orly and laterally to fill the vestibule extending tothe corners of the smile. In the composition of abeautiful smile, the form, balance, symmetry andrelationship of the elements make it attractive orunattractive. An expanse of soft tissue should notbe considered to be unaesthetic per se, but the waythis soft tissue is arranged relative to the teeth andlips is of aesthetic concern. Continuity of linearhorizontal form between the gingival expanse, theteeth and the upper lip is critical. Any asymmetryin this parallelism disturbs the sense of balance inthe composition, disturbing the flow and results inan unaesthetic smile (Fig. 12).

By this definition, a high lipline in itself may notbe unaesthetic if these basic rules are followed.However, in today's mass media-influencedculture, many people consider eventhe slightestexcessive display of gingival tissue -the " gummy

smile" -unattractive.The gummy smile or high lipline case with an

expanse of soft tissue can result from two basic

problems:

.altered passive eruption

.vertical maxillary excess.

The lips form the frame of a smile and as such, de-fine the aesthetic zone. Liplines have classicallybeen defined as being high, medium or low (6).

In the typical low lipline, only a portion of theteeth are exposed below the inferior border of the

upper lip.The high lipline shows a large expanse of gingiva

extending from the inferior border of the upper lipto the free-gingival margin.

The definitive diagnosis of the problem determinesthe treatment.

One of the clinical criteria in determining whichof these two factors is responsible for a" gummy

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Principles of aesthetic diagnosis

Fig. 6. Orthodontic clinical eruption sequence showinghow movement of the left central incisor in an incisal di-rection results in a concomitant change in the level of thefree gingival margin as well as the osseous crest

Fig. 7. Preoperative smile showing compensatory overe-ruption of the maxillary central incisors as a result of along-term anterior bruxing pattern. Note the unaestheticchange in gingival line as compared with the drape of the

upper lipFig. 8. Orthodontic appliance is in position showing the useof an intrusive archwire. The stainless steel archwire in apassive position lays in the manllary anterior vestibule.When ligated to the central incisor brackets, it exerts an in-trusive force.

Fig. 9. Postorthodontic result showing alignment of thegingiva on the two central incisors without harming theadjacent teeth. No surgery was performed in this situation.Compare with Fig. 7.

Fig 10. Computer simulation showing restorative differen-tial in preparation of cases where the gingival harmony isrestored with orthodontic intrusion versus surgical crown

lengthening

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Garber & Salama

Fig. II. Computer simulation showing a smile with the var-ious components in harmony. The incisal edge line followsthe form of the lower lip -while the line joining the tops ofthe free gingival margins form the upper lip. The teeth bi-laterally extend to fill the vestibules to the commissures ofthe lips.

Fig. 12. A preoperative maxillary anterior reconstruction inplace showing the lack of harmony between the variouscomponents of the smile, the teeth, the lips, and the gin-giva. The gingival line is diametrically opposed before themaxillary arch. Note the harmony developed in the postop-erative case between the lips, the teeth, and the gingivalscaffold.

Fig. 13. Preoperative view showing rather short, squat teethin which the height is inadequate relative to the width. Peri-odontal bone-soundingvia the sulcus indicates that there is

a large dimension between the free gingival margin and thecementoenamel junction, as well as space between cemen-toenamel junction and the osseous crest for insertion of thebiological width. The green line on the teeth is indicative ofthe preoperative level of the free gingival margin.

Fig. 14. A gingivectomy was performed to elevate the levelof the free gingival margin -developing a more proportion -ate form for the teeth, as well as removing an excessive dis-play of gingiva below the inferior border of the upper lip.

Fig. 15. Postoperative healing of the gingivectomy as wellas orthodontic repositioning of the right central incisorwithout closing the diastema provides for bonding in equalamounts between the two central incisor without closingthe diastema.

Fig. 16. Preoperative view of smile showing short nonpro-portionate teeth as well as an excessive display of gingiva.

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Principles of aesthetic diagnosis

cementoenamel junction of the tooth. Insubcategory A, the dimension between the level ofthe cementoenamel junction and the osseous crestis greater than 1 mm, which is sufficient for theinsertion of the connective tissue fibrousattachment component of the biological width. Insubcategory B, detected by the process of bonesounding via the sulcus, the osseous crest occurs inclose proximity to the cementoenamel junction,thereby diminishing the space for the insertion ofthe connective tissue of the biological width.

The biological width, which comprises thejunction epithelium, the connective tissue fibrousattachment and the sulcus, is co~sidered to be aninviolate parameter. This implies that thebiological width should not be impinged upon byrestorative endeavors. Based on early necropsystudies, the average dimensions of the biologicalwidth were considered to be approximately 2.7 mm-about 1 mm for the junctional epithelium, 1 mmfor the connective tissue attachment and 1 mm forthe sulcus. In clinical practice, we have found thisto be a more varied dimension often exceeding the3 mm average.

smile " relates to the basic shape of the teeth. If the

teeth appear to be somewhat short and squat -

meaning that the vertical dimension appears to betoo short as compared with the horizontaldimension, the gummy smile is probably due toaltered passive eruption.

If, however, the silhouette form of the toothappears to be normal and an expanse of tissue isexposed below the inferior border of the upper lip,this is probably due to an overgrowth of the maxillain a vertical dimension or a vertical maxillaryexcess.

In many situations, the gummy smile may be acombination of these two factors.

The gummy smile.

eruptIon

altered passive

Altered passive eruption is an aberration in normaldevelopment where a large portion of the ana-tomic crown remains covered by the gingiva. Thiscomplicates developing dentofacial harmony fortwo dominant reasons:

Treatment of type I -altered passive eruption

The typical case of altered passive eruption type I -

A exhibits short, square-Iooking teeth and an ex-panse of gingiva below the inferior border of theupper lip. A needle probing of the osseous crestthrough the gingival sulcus detects a distance be-tween the cementoenamel junction and the os-seous crest that is sufficient to maintain the biolog-ical width (Fig. 13). A gingivectomy using scalpel,electrosurgery or carbon dioxide laser will readilyremove this tissue. The tissue should be removedcervically in order not to compromise the inter-dental papillae. This procedure will result in a re-vised silhouette form for the tooth (Fig. 14) that ismore elliptical and attractive and will resolve theunwarranted excessive display of gingiva apparentduring smiling (Fig. 15).

.The tissue being positioned coronally on theteeth results in a silhouette form that is unattrac-tive. There is only a nominal degree of scallop tothe free gingival margin, resulting in a toothshape that is somewhat square instead of a moreattractive elliptical or ovoid form.

.The excess soft tissue tends to be displayedbelow the inferior border of the upper lip, com-plicating the desired relationship in that it makesa potentially medium lipline into a high lip line.

Altered passive eruption -type I-B

Diagnosis is confusing in this subcategory, as theclinical appearance is similar, with an excessiveamount of gingiva from the free gingival margin tothe mucogingival junction readily shown duringsmiling (Fig. 16). On bone sounding via the sulcus,it would appear that the osseous crest is at the

Altered passive eruption has been classified intotwo distinct types (4) .

In type I, there is typically an excessive amountof gingiva, as measured from the free gingivalmargin to the mucogingival junction.

In type II, there is a normal dimension of gingivawhen measured from the free gingival margin tothe mucogingival junction. Although these mightappear to be clinically similar in that there is tissueextended over the coronal portion of the tooth,therapeutically the diagnosis between the twotypes is essential to determine the appropriatetreatment modality.

Type I can be further subdivided on ananatomical histological basis into sub-categories Aand B. This subclassification depends on therelationship of the osseous crest to the

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Garber & Salama

ence of interdental papillae and realigning the gingivalmargin optimally, not with the cementoenamel junction,but with the drape of the upper lip.

Fig. 21. Postoperative early healing of the case followingthe second stage of electrosurgery. Compare with Fig. 16and note the more proportionate teeth as well as the di-minished amount of gingival display.

Fig. 22. Lateral oblique view of a patient with vertical max-illary excess in combination with altered passive eruption.The green line on the gingiva indicates the extent of the re-quired gingivectomy to develop gingival harmony as wellas optimal tooth proportion. The black lines on the incisaledges denote the tooth structure to be removed in cosmeticcontouring to develop ideal embrasure form and incisaledge line.

Fig. 17. The bone-sounding process viewed by making asubmarginal incision, leaving the free gingival margin inplace while elevating mucoperiosteal full-thickness flaps.With a probe in place, the dimension from the free gingivalmargin to the cementoenamel junction and level of the os-seous crest is evident.

Fig. 18. The osseous has been redeveloped apically with theform following and paralleling the rise and fall of the ce-mentoenamel junctions typical of this genetic phenotype.

Fig. 19. The flaps coapted and sutured in position just in-cisal to the cementoenamel junction

Fig. 20. Following initial healing of the flap procedure, agingivectomy/gingivoplasty is performed as part of thetwo-stage procedure using electrosurgery to fine-tune theharmony of the free gingival margin, ensuring the pres-

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Principles of aesthetic diagnosis

The sounding with a probe tends to identify themore incisally positioned outer cortical plate. Theproximity of the osseous crest to the cementoe-namel junction requires surgical relocation of thesoft tissue apically via reduction of the osseouscrest (Fig. 18, 19) (1, 5) to allow for insertion ofthese fibers in a more coronal position followed bya concomitant apical positioning of the junctionalepithelium and the sulcus. This ultimately resultsin the free gingival margin being positioned right atthe cementoenamel junction. The surgical proce-dure, however, may require modification depend-ing on the relative position of the upper lip to the

cementoenameljunction (Fig. 20, 21).

Altered passive eruption -type II

In altered passive eruption type II, the pathogno-monic short teeth are clinically evident, but thezone of masticatory mucosa is not excessive as intype I. This then requires reduction apically of theentire dentogingival complex, with or without os-seous reduction, to aesthetically solve the aesthetic

problem.

same level as the cementoenamel junction. Thiswould seem to be contrary to the concept of the bi-ological width, as the connective tissu~ fibrous at -

tachment cannot insert into the enamel and yetmust be present (Fig. 17) .Clinical and histologicalnecropsy observations suggest that, in altered pas-sive eruption type I- B, there is an added dimensionbuccolingually to the osseous form. This extrathickness to the osseous structure allows for anapical angulation of the bone crest from the gingi -

val aspect of the periodontal ligament side. Al-though periodontal connective tissue fibers nor-mally run horizontally across the osseous crest ex-tending from the cementum to the gingiva, in thisform of altered passive eruption, the fibers run api-cally' parallel to this angular crest, allowing for in-sertion of the connective tissue fibers just apical tothe cementoenamel junction in the cementum.

The gummy smile -verticalmaxillary excess

The gummy smile frequently results from a skeletaldysplasia (Fig. 22) I such as a hyperplastic growth ofthe maxillary skeletal base. This results in the teethbeing positioned farther away from the skeletalmaxillary base and a display of gingiva below theinferior border of the upper lip. Diagnosis in thehigh lipline case involving a vertical maxillary ex-cess requires ruling out the cases due to a superim-

Table 3. Treatment of the gummy smile: altered passive eruption or vertical maxillary excess

Condition Treatment options

Altered passive eruption type I-B Flap with osseous resection

Vertical maxillary excess -degree 2 Periodontics and restorative dentistry

Orthognathic surgery

Garber & Salama

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Principles of aesthetic diagnosis

Table 4. Desirable traits of an attractive smile

Teeth color

position

silhouette shape

Lips define the aesthetic zonethree forms ofliplines: high, medium, and lowthe geometry of harmonygingival line follows upper lip contourincisal edge line follows lower lip form

Fig. 23. The gingivectomy is performed with the CO2 laseron the upper right side, but contrasted to the left side. Thisis done prior to any orthognathic surgery to give the sur-geon a more precise guideline as to the degree of impactionrequired during his procedures.

Fig. 24. The patient following the orthognathic procedures.This depicts the patient with lips at rest showing a nominalamount of incisal edge as well as a full smile. The degree ofvertical translation of the lip between the rest and fullsmile is the required dimension of a tooth to eliminate anyshow of gingiva. This, however, may result in an excessivelylong tooth. The lip at rest is the limitation to vertical im-paction for the orthognathic surgeon, as any further im-paction will result in no show of incisal edge at rest and amore aged appearance for the patient. Here, following or-thognathic procedures, there is still a show of gingiva be-low the inferior border of the lip in full smile view.

Fig. 25. To eliminate this postorthognathic surgery show oftissue, the patient elected to have further periodontal sur-gery to lengthen the teeth -eliminating the gingiva. Thegreen dot on the teeth is indicative of the cementoenameljunction to which the original gingivectomy was done.Now the osseous structures redeveloped in a more apicallevel and the flap repositioned further apically to displaymore tooth structure.

Fig. 26. Postoperative early healing showing the relocatedgingiva line following bleaching of these teeth and cos-metic contouring of the incisal edges above the mandibu-lar teeth.

Fig. 27. A preoperative view of the completion of the orth-odontic phase prior to orthognathic surgery.

Fig. 28. The postoperative view following gingivectomy, or-thognathic procedure, surgical crown lengthening, bleach-ing, and cosmetic contouring 5 years following completionof the case.

Fig. 29. The implant site optimally developed showing acontinuity of form of the free gingival margin, as well as thethree-dimensional reconstruction of the papillae and rooteminence.

Fig. 30. Postoperative view of the lateral incisor and resto-ration in place. Note harmony with the rest of the naturalteeth, but supported by the soft tissue reconstruction tomake it indistinguishable from the adjacent dentition.

position of altered passive eruption in combina-tion with maxillary hyperplasia. These combinedcases should first be treated for any altered rela-tionship between gingiva and cementoenameljunction (Fig. 21). This results in the developmentof a more aesthetic tooth silhouette form and al-lows for more accurate diagnosis. Orthognatic pro-cedures can take place to reposition the maxilla.The combined cases require for optimal treatmenta multidisciplinary approach to treatment plan-ning involving an orthodontist, a periodontist, anorthognathic surgeon and a restorative dentist.

The classification of vertical maxillary excess(Tables 2, 3) was developed to help determine themost appropriate treatment modality. Thediagnosis relative to the degree of severity ispredicated upon first treating the altered gingivaldisplay (removing the altered passive eruptioncomponent) and to develop a normal tooth form(crown form). Degrees of severity I, II and III arethen determined by the amount of remaininggingiva displayed. The treatment modalities rangefrom orthodontic intrusion alone through complextreatments involving orthognathic surgery,orthodontics, restorative components and

periodontal plastic procedures.In vertical maxillary excess cases degrees II and

III involving orthognathic surgery, the treatmentplanning relates to developing the relationshipbetween the incisal edge and the lip at' rest. Insome combination cases, the vertical translation ofthe lip from rest to its position at maximal smilemay, in fact, exceed the normal length of a toothcrown. As such, patients must decide whether toaccept a nominal display of gingiva below theupper lip and normal crown dimensions or toprefer an increased length of the crowns and nodisplay of gingiva.

It is critical in these cases to treat to the positionof the lip at rest, as otherwise the surgeon mayoverimpact the maxilla, burying the incisal edgebeyond the vermilion border of the lip -resultingin a dramatically aged appearance.

In combination cases, the diagnostic proceduraltreatment is as follows:

27

Gingiva

Garber & Salama

Summary

As the public becomes increasingly concernedwith looking younger and healthy, aesthetic con-siderations will become increasingly more relevantin dental treatment planning. As such, dentistsmust define the basic tenets of an aesthetic smile -extending that vision beyond simply " pretty teeth "

to a concept whereby total dentofacial harmony isdeveloped. Aesthetics is not simply a matter for re-storative dentists -it uses restorative dentistry asone of the disciplines, but it is about beauty. Thesame rules that apply for a denture are thereforepertinent for crown and bridge and/ or implantsand must be applied in all aesthetic endeavors.

.First create an attractive silhouette form for theteeth developing normal anatomical form. Thiswill remove any altered passive eruption compo-nent from the case, leaving only the vertical max-illary excess or skeletal dysplasia evident. It alsogives the surgeon a definitive guideline as to thepotential lip-to-tooth relationships and theamount of impaction necessary (Fig. 23).

.The orthognathic procedure is limited by theincisal edge to lip at rest position. A minimum of2.0 mm of the incisal edge of the teeth should beshowh at rest; that is, the maxilla is not to beimpacted beyond this level (Fig. 24) .

.Following orthognathic impaction, any remain-ing gingival display may be removed as deter-mined by the patient's subjective needs by usinga periodontal flap with osseous resection accom-plished in a two-stage approach. The flap shouldfirst be replaced and sutured at its original posi-tion, and following initial healing, sculpted withelectrosurgery to develop optimal silhouettetooth form, thereby retaining the interdentalpapillae (Fig. 25-28) .

References

Diagnosis for total dentofacial aesthetics today in-volves a comprehensive knowledge of the desiredsmile composition as determined by its three basicelements: the teeth themselves, the gingival scaf -

fold and the lip framework. Developing these rela-tionships about the three basic tenets of a beautifulsmile incorporates:

.adhesive dentistry

.a multidisciplinary integrated approach

.implants.

When implants form part of the treatment plan, thebasic tenets relevant for removable prosthodonticsand conventional restorative work remain identi-cal. The high lip line is thus the most difficult for cli-nicians to deal with, because it exposes to the on-looker any restorative work. In any implant case, thebasic arrangement of the various components ofthe smile -the teeth, the lips, and the gingival scaf -

fold -must first be made harmonious prior to de-veloping the individual implant receptor sites withthe identical configuration to conventional teeth;that is, an interdental papilla on each side with arise and fall to the free gingival margin in betweenand the illusion of a root eminence -all in harmonywith the contralateral teeth (Fig. 29, 30) (Table 4).

1. Allen E~ Use ofmucogingival surgical procedures to en-hance esthetics. Dent Clin North Am 1988: 32: 307-330.

2. Eernimoulin I~ Luscher E, Muhlemann HR. Coronallyrepositioned periodontal flap. Clinical evaluation afterone year. I Clin Periodontol1975: 2: 1-13.

3. Cohen D, Ross S. The double papillae flap in periodontaltherapy. I Periodontol1968: 39: 65-70.

4. Coslet IG, Vanarsdall RL, Weisgold A. Diagnosis andclassification of delayed passive eruption of the dento-gingival junction in the adult. Alpha Omegan 1977: 70(3): 24-28.

5. Garber DA, Rosenberg ES. The edentulous ridge in fIXedprosthodontics. Compendium 1981: 2: 212-224.

6. Goldstein RE. Esthetics in dentistry. Philadelphia: I.E.Lippincott Co., 1976.

7. Gottlow I, Nyman S, KarringT, Lindhe I. Treatment oflo-calized gingival recessions with coronally displacedflaps and citric acid. An experimental study in the dog. IClin Periodontol1986: 13: 57-63.

8. Langer E, Calagna L. The subepithelial connective tissuegraft. I Prosthet Dent 1980: 44: 363-367.

9. Lombardi RE. The principles of visual perception andtheir clinical application to denture esthetics. I ProsthetDent 1973:29:358-382.

10. Nabers CL. Free gingival grafts. Periodontics 1966: 4:243-245.

11. Pennel EM, Higgison ID, Towner TD, King KG, Fritz ED,Salder IF. Oblique rotated flap. I Periodontol 1965: 36:305-309.

12. Seibert IS. Reconstruction of deformed, partially eden-tulous ridges, using full thickness onlay grafts. II. Pros-

thetic/periodontal interrelationships. Compendium1983: 4: 549-562.

13. Sullivan HC, Atkins IH. Free autogenous gingival grafts.I. Principles of successful grafting. Periodontics 1968: 6:121-129.

14. Sullivan HC, Atkins IH. Free autogenous gingival grafts.III. Utilization of grafts in the treatment of gingival re-cession. Periodontics 1968: 6: 152-160.

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