Gingival Tissue

Thick Versus Thin Gingival Tissue: A Key Determinant in Tissue Response to Disease and Restorative Treatment

Richard T. Kao, DDS, PhD, and Kirk Pasquinelli, DDS

Copyright 2002 Journal of the California Dental Association.

About the Authors:

Richard T. Kao, DDS, PhD, is an adjunct associate professor in the Department of Periodontology at the University of the Pacific School of Dentistry and is in private practice in Cupertino, Calif.

Kirk Pasquinelli, DDS, is an assistant clinical professor in the Division of Periodontology at the University of California at San Francisco School of Dentistry and is in private practice in San Francisco.

During the treatment planning process, it is important for clinicians to appreciate that the differences in gingival tissue can affect treatment outcomes. The concept of thick versus thin gingiva has previously been introduced. This concept has been expanded to describe the different ways these tissue types respond to inflammation, restorative trauma, and parafunctional habits. The resulting defects from these traumatic events will dictate varying treatment management modalities. As restorative dentists begin to appreciate the differences in gingival morphology, they will discover that working with thick gingiva is easier and more predictable. In the past, restorative dentists had no options for influencing the tissue quality they had to work with during restorative procedures. Recent advances in periodontal surgery have made it possible not only to reposition tissues to meet esthetic demands, but also to change the tissue quality of the restorative environment for more-predictable treatment outcomes.

During clinical examinations, periodontal information-gathering tends to focus on quantitative information such as pocket depth, recession, mobility, and furcation involvement. Not enough time is devoted to evaluating the qualitative nature of the periodontium or, more notably, the gingiva. This is unfortunate since the quality of the gingiva will often define how restorations will appear esthetically. Additionally, it will provide the clinician with insight into how periodontal defects result and what treatments are required. This paper will describe the importance of differentiating between thick and thin gingiva in the examination phase in preparation for treatment planning. Additionally, it will introduce a new paradigm shift.

The gingiva is that part of the masticatory mucosa which surrounds the cervical portion of the teeth and acts as the covering for the alveolar housing. Clinicians would all agree that an ideal healthy gingiva would be pink, be firm, be adjacent to the cemento-enamel junction, and fill the interproximal area fully (Figure 1). There is less agreement regarding what gingival features are risk predicators for periodontal breakdown. Quantitative descriptions of gingival recession or clefting are not consistently used nor fully appreciated. Qualitative gingival descriptors such as "minimal attached gingiva" or "thick versus thin attached gingiva" are seldom documented. Yet this information can be useful in telling the clinician which areas are at risk for periodontal breakdown in the presence of inflammation, restorative trauma, and parafunctional habits.

Why is gingival tissue quality important? The gingival tissue serves as the "picture framework" for a patient’s smile and restorative treatment. In this day of esthetic dentistry, it is paramount for the restorative dentist to consider how the gingival tissue is going to respond to both restorative margins and gingival inflammation. This appreciation may help clinicians find answers to past dilemmas such as why the gums receded on a recently cemented crown; why one extraction caused so much ridge atrophy while another did not; or why a new patient with generalized gingival recession appeared as if he had pocket reduction surgery despite the patient’s adamant denial. An appreciation of gingival tissue will also help clinicians have a better understanding of the periodontist’s viewpoints. This will encourage better teamwork and enhance patient treatment.

The Difference Between Thick and Thin Gingiva

Historically, Ochsenbein and Miller¹ have discussed the importance of "thick versus thin" gingiva in restorative treatment planning. But what is this difference?

Thick gingival tissue is probably the image most associated with periodontal health (Figure 1, Table 1). The tissue is dense in appearance with a relatively large zone of attachment. The gingival topography is relatively flat with a suggestion of thick underlying bony architecture. Surgical evaluation of these areas often reveals relatively thick underlying osseous form (Figures 2a and b).

Thin gingival tissue tends to be delicate and almost translucent in appearance (Figures 3a through d, Table 2). The tissue appears friable with a minimal zone of attached gingiva. The soft-tissue topography is highly accentuated and often suggestive of thin or minimal bone over the labial roots. Surgical evaluation often reveals thin labial bone with the possible presence of fenestration and dehiscence. Unlike thick gingiva, this tissue is highly sensitive to trauma and inflammation.

Classically, clinicians familiar with the concept of thick versus thin gingiva will describe a patient’s gingival tissue quality as either a thick or thin case. This is true only when the gingival tissue is consistent. Frequently there are situations with regions of thick and thin gingiva. Since thick and thin gingiva is a gross description of the gingival-osseous housing complex, there is often a regional variation of labial plate thickness. Clinicians will see a mixture of thick and thin gingiva in the same dentition. Areas of thin labial plate are commonly associated with the canine eminencies, the mesial roots of maxillary first molars, and mandibular incisors. These areas tend to have thin gingiva. So for the clinician, it is better to describe the case as thick, thin, or mixed thick-thin gingiva. It is important to note the tissue quality in the region to be treated.

The quality of the gingiva may change depending on the age of the patient.² For a young child 7 to 9 years old, the gingiva may appear thin with a minimal zone of attached gingiva. The zone of attached gingiva and volume will increase with growth, tooth eruption, and jaw development. After growth, the volume of the gingival tissue and the osseous housing remain relatively stable in health, but the width of the attached gingiva may continue to increase. Since the mucogingival junction remains stable throughout life, the increase in width is suggestive of slow eruption secondary to occlusal wear.

Periodontal Response to Insult

Thick and thin gingiva will respond differently to infectious, restorative, and parafunctional insults (Table 3).

In thick gingiva, the gingival-osseous housing is comparatively thicker. With acute inflammation secondary to a periodontal/endodontic abscess, cracked tooth, or failing endodontic treatment, clinicians tend to see either encapsulation of the infection through abscess formation, venting through a parulis, or a perio-endodontic lesion through the periodontal pocket. Marginal inflammation can be described in the acute form as marginal redness to a chronic form that is magenta-cyanotic in appearance. With chronic inflammation, marginal gingivitis is present with gingiva coloration ranging from red to magenta. The gingiva may range from a normal shape to a boggy, enlarged shape. As inflammation persists, periodontal pocketing tends to occur. In regions with a relatively thick bulk of bone, the pocket formation occurs in conjunction with infrabony defects. These defects tend to occur in areas where there is a large region of interproximal bone and on the labial/lingual aspect when tori are present. Surgical procedures are more predictable with thick gingiva. There is less postsurgical remodeling so the clinician can better predict tissue position. This is important in crown-lengthening procedures and extraction of teeth preceding implant placement. Lastly, the thick gingival-osseous housing makes this tissue more resistant to clinical and parafunctional insults such as toothbrush abrasion, the packing of impression cords, and poor restorative margins.

Thin gingiva responds differently than thick tissue. Acute insults such as trauma, fracture, abscess, or viral infection result not only in abscess/parulis formation, but also in the development of gingival recession/clefting. Rarely do these defects heal. With chronic periodontal disease, the marginal inflammation tends to be reddish in appearance. As inflammation persists, attachment loss occurs by gingival recession without significant pocket formation. This tendency toward gingival recession is significant for the clinician in terms of understanding how periodontal disease progresses differently in these patients and how these tissues respond to restorative procedures.

Monitoring of periodontal disease progression requires diligence on the part of the clinician. Since dental training and record-keeping are largely focused on pocket depth, clinicians often will not fully appreciate periodontal disease progression in patients with thin gingiva. In these patients, disease progression occurs with an increase in gingival recession rather than pocket depth. In fact, these patients may appear as if they have had periodontal pocket reduction surgery because of the prevalence of gingival recession seen in patients following this type of surgery. Further questioning often reveals that they have never had advanced periodontal or surgical care. In these thin cases, it is critical for the clinician to realize that attachment loss is not only indicated by how deep the pockets are, but also by the amount of recession present. Frequently, pocket depth is insignificant in comparison to recession measurements.

Frequent analysis of attachment loss is important in thin cases. However, the manual recording of pocket depth and recession is so tedious that most clinicians only monitor pocket depth. Focusing only on pocket depth has the potential of giving one a false view that the patient is periodontally stable. With computer charting, attachment loss is easier to monitor; however, most software programs only record one recession measurement. Only with six-point pocket depth and recession measurements can one accurately monitor a patient’s periodontal health status.

Gingival recession is a frequent clinical finding in patients with thin gingiva. If a tooth is in buccal version, localized gingival recession can occur. Aggressive toothbrushing can result in a zone of gingival recession. This is most notable in teeth with buccal prominence, such as the cuspids and maxillary first molars. Regardless of whether the trauma is from toothbrush abrasion, eating, or localized recurrent apthous ulcers or viral infections, these gingival areas are highly susceptible to recession.

Differential Management of Defects Associated With Thick and Thin Gingiva

Since the responses to infectious, restorative, and parafunctional insults by thick and thin tissues are different, the clinical management of these defects also varies (Table 4).

In thick tissue, acute infections are managed with curettage, irrigation with betadine solution (diluted 1:10 with water),^3,4 and antibiotics as needed. Chronic inflammation is managed with scaling and root planing. As periodontal disease progresses, deep pockets may be managed with flap osseous surgery. Associated infrabony defects can be managed by any combination of curettage, osseous contouring, and regenerative procedures. Crown lengthening procedures are relatively predictable with soft- and hard-tissue contouring as needed. With tooth extraction, ridge augmentation is often not necessary since there is adequate bulk of labial bone. In fact, grafting associated with a ridge preservation procedure will often compromise implant osseointegration since grafted materials such as demineralized freeze-dried allograft⁵ do not readily resorb. Some of the graft materials remain amalgamated with the reparative bone and do not contribute to osseointegration.

In thin gingiva, the management approach is different. Both acute and chronic inflammation will result in gingival recession. The periodontal pockets are generally 2 to 4 mm deep. The definitive treatment for these cases often consists of scaling and root planing along with oral hygiene instruction. There are no pocket or infrabony defects that form because the thin bony plate resorbs in advance of the recession. Surgical procedures are also difficult since it is hard to predict the reparative result of the healing tissue. With crown lengthening and any flap osseous procedure, it is difficult to anticipate the final positioning of the thin soft and hard tissue, partially due to the fact that each time a surgical flap is reflected, there is at least 0.5 to 0.8 mm of bone loss. ^5,6 With this loss, the thin labial plate recedes apically, and the soft tissue will follow. The extent of this recession is difficult to predict due to the varying thickness of the labial plate. Although a crown lengthening procedure may be necessary, it is important for the clinician to allow for more healing time so that the tissue can stabilize. This may require up to a minimum of six months or more for esthetically important areas such as the anterior maxillary segment. With extraction, the labial plate is prone to fracture. As the ridge heals, there is a tendency for the ridge to remodel apically as well as lingually. To prevent this, ridge preservation procedures such as guided bone regeneration and/or soft tissue grafting are indicated to minimize ridge atrophy. Further treatment to correct residual ridge deficiencies may include ridge augmentation procedures.

Engineering a Change in the Periodontium

Based on the preceding discussion, it should be apparent that thick gingival tissue is easier and more predictable to manage restoratively and surgically. The literature on restorative treatment supports this finding. Until 10 to 15 years ago, restorative dentists had little choice in determining the type of gingiva with which they had to work. Recent advances in periodontal surgery have eliminated many of these constraints.

Restorative dentists now have the option of referring the patient to the periodontist for corrective procedures. These procedures will develop the gingival environment into a "psuedo-thick" case. For areas with thin gingiva or gingival recession, a connective tissue graft procedure may be performed. This not only thickens the soft tissue so it is more resistant to trauma, but it can also cover exposed root surfaces (Figures 4a and b). When these strategies are used in conjunction with esthetic crown lengthening, it is possible for the periodontist to develop the gingiva volumetrically and in the apical/coronal direction to create the appropriate "framework" for restorative treatment. Similarly, the periodontist can manage extraction in the thin case with ridge preservation procedures to minimize ridge atrophy and/or ridge augmentation to correct ridge deficiencies (Figures 5a through c). In incidences where implants are desired, immediate implants can be placed to preserve not only the bone, but also the soft tissue, including the papilla (Figures 6a through d). These periodontal procedures convert a thin case into a tissue type that the restorative dentist can work with more easily and predictably.

Summary

A new paradigm shift has occurred in periodontics. In this new era, it is important for restorative dentists to consider the thick and thin gingival-osseous housing of the dentition. As clinicians begin to appreciate how thick versus thin tissues respond to infectious, restorative, and parafunctional trauma, they will be better able to predict the defects that will result and prescribe the appropriate treatment. Even more important for the restorative dentist is the realization that thick gingiva is a more favorable tissue environment for restorative procedures. With advances in periodontal plastic surgery, it is possible to transform a thin case into a more manageable "pseudo-thick" case. This paradigm shift will permit clinicians to be more effective in diagnosing periodontal problems and prescribing treatment. Additionally, these new procedures give them the ability to modify the tissue environment when they need to deliver esthetic restorations.

References

1. Ochsenbein C, Ross A, A re-evaluation of osseous surgery. Dent Clin North Am 13:87-103, 1969.

2. Ainamo J, Talari A, The increase with age of the width of attached gingiva. J Periodont Res 11:182-8, 1976.

3. Rosling BG, Slots J, et al, Topical antimicrobial therapy and diagnosis of subgingival bacteria in the management of inflammatory periodontal disease. J Clin Periodontol 13:975-81, 1986.

4. MG Jorgensen, J Slots, Antimicrobials in periodontal maintenance. J Dental Hygiene 75:233-9, 2001.

5. MA Reynolds, GM Bowers, Fate of demineralized freeze dried bone allografts in human intrabony defects. J Periodontol 67:150-7, 1996.

6. Wilderman M, Pennel B, et al, Histogenesis of repair following osseous surgery. J Periodontol 41:551-65, 1970.

7. Moghaddas H, Stahl S, Alveolar bone remodeling following osseous surgery. A clinical study. J Periodontol 51:376-81, 1980.

To request a printed copy of this article, please contact/Richard T. Kao, DDS, PhD, 10440 So. DeAnza Blvd., Suite #D-1, Cupertino, CA 95014 or richkao@value.net.

Legends

Figure 1. The ideal smile is supported by a thick gingiva with a stippled appearance. The gingival crest of the maxillary teeth follows the flow of the upper lip.

Figures 2a and b. The clinical presentation of thick gingiva and the type of osseous architecture associated with this gingival tissue type.

Figures 3a through c. Clinical presentation of thin gingiva is characterized by thin friable tissue. It is associated with clefts, perforations, and gingival recession.

Figure 3d. The osseous architecture associated with this gingival tissue type is characterized by fenestration and dehiscence.

Figures 4a and b. Thin gingival tissue and recession can be corrected with a connective tissue graft to thicken the gingiva and cover exposed root surfaces. This approach permits repositioning of the gingiva in the coronal direction, while apical positioning can be performed by a variety of treatments including apical positioned gingival flap procedure, gingivectomy, and crown lengthening. These procedures permit the development of an esthetic gingival relationship to the restorations.

Figures 5a-c. Ridge preservation and augmentation have been performed in this case. Ridge deficiency is present in the #13 position from a previous extraction, and tooth #12 is planned for extraction. Volumetric increase in the gingiva was obtained with periodontal grafting for the #13 region, and ridge preservation was performed after extracting tooth #12. These periodontal procedures improve the gingival-restorative appearance to be more natural in appearance.

Figures 6a and b. To minimize soft- and hard-tissue loss associated with tooth extraction, an immediate implant was placed.

Figures 6c and d. An impression was taken such that a provisional temporary was placed to support the gingiva and adjacent papilla. Note that there was minimal tissue loss after six months.