The Relationship Between the Width of Keratinized Gingiva and Gingival Health

by

NIKLAUS P. L A N G *

HARALD L E * *

INTRODUCTION

IN MAN T H E KERATINIZED gingiva includes the free and the attached gingiva and extends from the gingival margin to the mucogingival junction. 1 The width of the keratinized gingiva may vary between 1 and 9 mm. 2 , 3

The characteristics of the gingiva on the facial aspect have been described by several authors. 1 7 However, only one recent study has reported on the width of the lingual keratinized gingiva of the mandible.7

Although not substantiated, it is generally believed that an adequate width of keratinized gingiva is important for maintaining gingival health. This has resulted in the introduction of numerous surgical procedures to increase the width of gingiva. 8 3 0 However, the question of how much gingiva is "adequate" has not been investigated.

The purpose of the present investigation was to examine the width of the facial and lingual keratinized gingiva and to determine how much keratinized gingiva is adequate for the maintenance of gingival health.

MATERIAL AND METHODS

Thirty-two dental students between 19-29 years of age with no pathologic pockets performed supervised oral hygiene (daily supervision with the Plak-Lite disclosing system) 3 1 for 6 weeks. Following this period, the gingiva of all buccal and lingual tooth surfaces was assessed using the Gingival Index system.3 2 Oral hygiene was scored on all surfaces according to the criteria of the Plaque Index system.3 3 The identification of the mucogingival junction was facilitated by staining with Schiller's IKI solution. 3 4 Using this method, the epithelium of the alveolar mucosa yielded an iodine-positive reaction while the keratinized gingiva was iodine-negat i v e , 3 4 3 6 (Figure 1 a,b). After application of the Schiller solution, the width of keratinized gingiva was measured

FIGURE 1. Clinical photographs showing the mucogingival junction a) without stain b) after application of the Schiller IKI solution.

to the nearest 0.5 mm from the gingival margin to the mucogingival junction using a specially graded periodontal probe. The depth of the gingival crevices was also measured. In order to compare the results of the present study to results from previous studies the width of attached gingiva was determined by subtracting the crevicular depth from the width of keratinized gingiva.

Gingival exudate was assessed37 on all (116) buccal and lingual surfaces which had 2 mm or less of keratinized gingiva. In addition, the amount of gingival exudate from 118 tooth surfaces randomly selected from a total of 371 which had 2.5 to 3.0 mm gingiva was measured. Only plaque free surfaces were scored.

RESULTS

After the six weeks of controlled oral hygiene the mean individual Plaque Index (PI I) was 0.22 (range 0.00-0.57). The mean individual Gingival Index (GI) was 0.09 (range 0.04-0.25). The crevicular depth averaged 1.0 mm (range 0.5-1.5 mm).

From a total of 1406 tooth surfaces, 1168 were completely plaque free.

*Research Associate, Department of Periodontology, Royal Dental College, Aarhus, Denmark.

**Professor and Chairman, Department of Periodontology, Royal Dental College, Aarhus, Denmark.

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624 Lang and Le J. Periodontol. October, 1972

MEAN WIDTH OF KERATINIZED GINGIVA

FIGURE 2. Pattern of variation in the mean width of keratinized gingiva in 32 individuals (19-29 years of age) with excellent oral hygiene and healthy gingiva.

The facial keratinized gingiva was widest in the area of upper and lower incisors and narrowest adjacent to the maxillary and mandibular canines and first premolars (Figure 2) . The lingual gingiva of the lower jaw exhibited its greatest width in the area of the premolars and molars. The incisors showed the narrowest lingual gingiva (Figure 2) . In the maxilla the facial

gingiva was generally 0.5-1 mm wider than in the mandible (Figure 2) .

Most surfaces ( > 80%) with 2.0 mm or more keratinized gingiva were clinically healthy, (Figure 3) and 76% of these same surfaces failed to show gingival exudation (Figure 4) . On the other hand, all surfaces

PERCENTAGE OF SURFACES

FIGURE 3. Proportion of Gingival Index score 0 to 1 to 2 in surfaces of varying width of keratinized gingiva (1.0-25.0 mm) of 1168 plaque free teeth.

625 Keratinized Gingiva and Gingiva Health Volume 43 Number 10

PERCENTAGE OF SURFACES

FIGURE 4. Proportion of gingival exudate measurements 0 to 03-0.5 to 0.6-1.0 to greater than 1.0 mm in surfaces of varying width of keratinized gingiva (1.0-3.0 mm) of 234 plaque free teeth.

with less than 2.0 mm of keratinized gingiva exhibited clinical inflammation and varying amounts of gingival exudate (Figures 3, 4) . Generally, the Gingival Index and gingival exudate scores increased as the width of the keratinized gingiva decreased (Figures 3, 4 ) . The maximum score during this examination was G I = 2 (moderate inflammation) which occurred only in surfaces whose width of keratinized gingiva was 2 mm or less (Figure 4 ) .

Figure 5 compares the distribution of variation of the width of attached gingiva found in the present study to that of previous studies.2' 3 , 7 The similarity between these results is apparent.

DISCUSSION AND CONCLUSION

The present investigation has shown that the pattern of variation in the width of the facial keratinized gingiva minus the crevicular depth agrees with previous studies on the width of attached gingiva. 2 , 3, 5 , 7 Similarly, it corroborates recent data on the width of the lingual attached gingiva.7 In this study the width of the lingual keratinized gingiva varied between 1 and 8 mm. The smallest width was usually seen in the area of the anterior teeth, and the widest gingiva was found adjacent to premolars and molars. This pattern of variation is almost the reverse of that of the facial gingiva.

The present material has also clearly demonstrated that although tooth surfaces may be kept free of clinically detectable plaque, areas with less than 2 mm of keratinized (which means less than 1 mm of attached) gingiva persisted to remain inflamed. The fact that inflammation persisted in these areas irrespective of

ATTACHED GINGIVA OF BUCCAL SURFACES

FIGURE 5. Comparison of the pattern of variation in the mean width of attached gingiva in the present study to those of previous studies.

626 Lang and Le J. Periodontol. October, 1972

the presence or absence of frenum insertions, suggests that the inflammatory situation in the gingiva is not a result of only mechanical irritation from these structures. Rather it is conceivable that a movable gingival margin would facilitate the introduction of microorganisms into the gingival crevice resulting in a thin subgingival bacterial plaque which would be difficult to detect and not easily removed by conventional tooth-brushing.

The regions which consistently showed the narrowest width of keratinized gingiva were the lingual surface of the lower anteriors and the buccal surface of the lower canines and first premolars. However, the study has shown that these surfaces which averaged nearly 3 mm in width should be adequate to maintain gingival health. Although not a problem from a preventive point of view, the narrow keratinized gingiva on the lingual of the lower anteriors may pose a problem in prostho-dontic and periodontal treatment. For example, it is required that if lower partial removable appliances are to be equipped with a lingual bar, the lingual area should have a minimum width of 4 mm keratinized gingiva. 3 8 ' 3 9 This requirement may be difficult to satisfy in the average patient since the mean width of the lingual gingiva adjacent to the lower anterior teeth is usually less than 3 mm.

It is apparent in periodontitis that pathologic pockets may easily extend beyond the mucogingival junction. Although procedures have been devised for correction this problem when it occurs on the facial aspect, to the best of our knowledge, modern periodontal surgery offers no specific method for increasing the width of keratinized gingiva on the lingual surface of the lower incisors.

Furthermore, since it would appear from this study that less gingiva is needed to maintain health than generally believed, a critical reappraisal of the indications for performing anyone of the many surgical procedures available for increasing the width of gingiva must be undertaken.

SUMMARY

The study undertook to examine the width of the facial and lingual keratinized gingiva and to determine how much gingiva is "adequate" for the maintenance of gingival health. After 6 weeks of supervised oral hygiene the gingival health of 1406 buccal and lingual surfaces in 32 dental students was assessed according to the criteria of the Gingival Index system. The width of keratinized gingiva was measured after the application of the Schiller I K I solution. Gingival exudation was measured on all buccal and lingual surfaces which had 2 mm or less of keratinized gingiva and in a randomly selected number of tooth surfaces with more than 2

mm gingiva. Only plaque free surfaces were scored. Previous observations on the width and the pattern of variation of keratinized gingiva were confirmed. It was demonstrated that gingival health is compatible with a very narrow gingiva. However, in areas with less than 2 mm keratinized gingiva inflammation persisted in spite of effective oral hygiene. It is suggested that 2 mm of keratinized gingiva (corresponding to 1 mm attached gingiva in this material) is adequate to maintain gingival health.

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2. Bowers, G.: A study of the width of attached gingiva. J. Periodont. 54:201-209, 1963.

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4. Fehr, C. and Mhlemann, H. R.: The surface of the free and attached gingiva studied with the replica method. Oral. Surg. 5:649-655, 1955.

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6. Bernimoulin, J. P., Son, S. and Regolati, B.: Bio-metric comparison of three methods for determining the mucogingival junction. Helv. odont. Acta 75:118-120, 1971.

7. Coppes, L.: Routine-Sulcusdieptemetingen in de parodontologie. Het belong-de betrouwbaarheid-de toepass-ing. Academisch proefschrift. Universiteit van Amsterdam. 117-135, 1972.

8. Gottsegen, R.: Frenum position and vestibule depth in relation to gingival health. Oral Surg. 7:1069-1078, 1954.

9. Nabers, C. L.: Repositioning the attached gingiva. J. Periodont. 25:38-39, 1954.

10. Grupe, H. E. and Warren, R. F.: Repair of gingival defects by a sliding flap operation. J. Periodont. 27:92-95, 1956.

11. Ariaudo, A. A. and Tyrrell, H. A.: Repositioning and increasing the zone of attached gingiva. J. Periodont. 25:106-110, 1957.

12. Ochsenbein, C : Newer concepts of mucogingival surgery, J. Periodont. 57:175-185, 1960.

13. Bohannan, H. M.: Studies in the alterations of vestibular depth. I. Complete Denudation. J. Periodont. 55:120-128, 1962.

14. Bohannan, H. M.: Studies in the alterations of vestibular depth. II. Periosteum retention. J. Periodont. 55: 354-359, 1962.

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16. Corn, H.: Edentulous area pedicle grafts in mucogingival surgery. Periodontics 2:229-242, 1964.

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19. Edlan, A. and Mejchar, B.: Parodontologisch in-

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dizierte Vertiefung des unteren Mundvorhofes. Parodon-tologie 75:87-94, 1964

20. Friedman, N. and Levine, L.: Mucogingival Sur-gery: Current status. J. Periodont. 55:5-21, 1964.

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Announcements CONTINUING EDUCATION COURSES

FALL SEMESTER1972

COLLEGE OF MEDICINE AND DENTISTRY OF NEW JERSEY

NEW JERSEY DENTAL SCHOOL 201 Cornelison Avenue Jersey City, N.J. 07304

Course TitleP-l Periodontics for the General Practitioner; FaculyDr. A. Formicola and Staff; Dates 9-20-72 (Wed.); Fee$40.*

Course TitleCE-2 Getting Prevention Through To Your Patients; FacultyDr. J. Mittelman; Dates10-18-72 (Wed.); Fee$50.

Course TitleCE-3 Principles of Occlusion; FacultyDr. N. Guichet; Dates 11-13, 14, 72 (Mon. and Tues.); Fee$95 (Dentists) $60 (Aux.). *No tuition for N.J. dentists. However, a $10. registration fee is required for each course.

FOR INFORMATION AND APPLICATION, WRITE TO: Dr. Daniel Isaacson Director of Continuing Education New Jersey Dental School 201 Cornelison Avenue Jersey City, New Jersey 07304

ARMY DENTAL RESEARCH INSTITUTE EARN AWARD AT ARMY SCIENCE CONFERENCE

On June 21, 1972 the United States Army Institute of Dental Research team of Brigadier General Surindar N. Bhaskar, Colonel Arthur Gross and Colonel Duane E. Cutright presented a study of their work with the pulsating water jet device at the Army Science Conference at West Point. Their contribu-tion to Army research and development was judged to be among the nine most significant in all areas of research.

Scientists from throughout the Army Research and Develop-ment Command had submitted a total of 497 proposals for papers to be presented at the conference. Of these, 100 were selected by a panel of Judges for presentation. Papers selected represented all areas of Army research, and included such subjects as communications, computer systems and nuclear research as well as medical studies.

At the end of the week-long conference, the panel of scien-tists selected the nine best papers presented. Authors of these studies received medals, certificates, and cash awards.

The studies conducted at the United States Army Institute of Dental Research led to the use of the pulsating water jet devices in the debridement of combat wounds in Vietnam. These techniques have now been adopted for the management of wounds in all parts of the body.

This is the first time that dental research has won such an award at the Army Science Conference.