The Relationship Between the Width of Keratinized Gingiva and Gingival Health by NIKLAUS P. LANG* HARALD LÖE** INTRODUCTION IN MAN THE KERATINIZED gingiva includes the free and the attached gingiva and extends from the gingival mar­ gin 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.17 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 im­ portant for maintaining gingival health. This has resulted in the introduction of numerous surgical procedures to increase the width of gingiva.830 However, the question FIGURE 1. Clinical photographs showing the mucogingival of how much gingiva is "adequate" has not been inves­ junction a) without stain b) after application of the Schiller tigated. IKI solution. The purpose of the present investigation was to ex­ amine the width of the facial and lingual keratinized to the nearest 0.5 mm from the gingival margin to the gingiva and to determine how much keratinized gingiva mucogingival junction using a specially graded perio­ is adequate for the maintenance of gingival health. dontal 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 MATERIAL AND METHODS of attached gingiva was determined by subtracting the Thirty-two dental students between 19-29 years of crevicular depth from the width of keratinized gingiva. age with no pathologic pockets performed supervised Gingival exudate was assessed37 on all (116) buccal oral hygiene (daily supervision with the Plak-Lite® dis­ and lingual surfaces which had 2 mm or less of kera­ closing system)31 for 6 weeks. Following this period, tinized gingiva. In addition, the amount of gingival exu­ the gingiva of all buccal and lingual tooth surfaces was date from 118 tooth surfaces randomly selected from assessed using the Gingival Index system.32 Oral hy­ a total of 371 which had 2.5 to 3.0 mm gingiva was giene was scored on all surfaces according to the criteria measured. Only plaque free surfaces were scored. of the Plaque Index system.33 The identification of the mucogingival junction was facilitated by staining with 34 Schiller's IKI solution. Using this method, the epithe­ RESULTS lium of the alveolar mucosa yielded an iodine-positive After the six weeks of controlled oral hygiene the reaction while the keratinized gingiva was iodine-nega­ 3436 mean individual Plaque Index (PI I) was 0.22 (range tive, (Figure 1 a,b). After application of the Schiller 0.00-0.57). The mean individual Gingival Index (GI) solution, the width of keratinized gingiva was measured was 0.09 (range 0.04-0.25). The crevicular depth aver­ *Research Associate, Department of Periodontology, Royal aged 1.0 mm (range 0.5-1.5 mm). Dental College, Aarhus, Denmark. **Professor and Chairman, Department of Periodontology, From a total of 1406 tooth surfaces, 1168 were com­ Royal Dental College, Aarhus, Denmark. pletely plaque free. 623 624 Lang and Löe 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 gingiva was generally 0.5-1 mm wider than in the of upper and lower incisors and narrowest adjacent to mandible (Figure 2). the maxillary and mandibular canines and first pre­ molars (Figure 2). The lingual gingiva of the lower Most surfaces (> 80%) with 2.0 mm or more kera­ jaw exhibited its greatest width in the area of the pre­ tinized gingiva were clinically healthy, (Figure 3) and molars and molars. The incisors showed the narrowest 76% of these same surfaces failed to show gingival lingual gingiva (Figure 2). In the maxilla the facial 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. Volume 43 Keratinized Gingiva and Gingiva Health62 5 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 ATTACHED GINGIVA OF BUCCAL SURFACES 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 GI = 2 (moderate inflammation) which occurred only in sur­ faces 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 gin­ giva minus the crevicular depth agrees with previous studies on the width of attached gingiva.2, 3, 5,7 Simi­ larly, 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 varia­ tion 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 clin­ ically detectable plaque, areas with less than 2 mm of keratinized (which means less than 1 mm of attached) FIGURE 5. Comparison of the pattern of variation in the gingiva persisted to remain inflamed. The fact that mean width of attached gingiva in the present study to inflammation persisted in these areas irrespective of those of previous studies. 626 Lang and Löe J. Periodontol. October, 1972 the presence or absence of frenum insertions, suggests mm gingiva. Only plaque free surfaces were scored. that the inflammatory situation in the gingiva is not Previous observations on the width and the pattern of a result of only mechanical irritation from these struc­ variation of keratinized gingiva were confirmed. It was tures. Rather it is conceivable that a movable gingival demonstrated that gingival health is compatible with a margin would facilitate the introduction of microorgan­ very narrow gingiva. However, in areas with less than isms into the gingival crevice resulting in a thin sub­ 2 mm keratinized gingiva inflammation persisted in gingival bacterial plaque which would be difficult to spite of effective oral hygiene. It is suggested that 2 mm detect and not easily removed by conventional tooth- of keratinized gingiva (corresponding to 1 mm attached brushing. gingiva in this material) is adequate to maintain gin­ gival health. 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 REFERENCES lower canines and first premolars. However, the study 1. Orban, B.: Clinical and histologic study of the sur­ has shown that these surfaces which averaged nearly 3 face characteristics of the gingiva. Oral Surg. 7:827-841, mm in width should be adequate to maintain gingival 1948. health. Although not a problem from a preventive point 2. Bowers, G.: A study of the width of attached gin­ giva. J. Periodont. 54:201-209, 1963. of view, the narrow keratinized gingiva on the lingual 3. Ainamo, J. and Löe, H: Anatomical characteristics of the lower anteriors may pose a problem in prostho- of gingiva. A clinical and microscopic study of the free dontic and periodontal treatment. For example, it is and attached gingiva. J. Periodont. 57:5-13, 1966. required that if lower partial removable appliances are 4. Fehr, C. and Mühlemann, H. R.: The surface of the to be equipped with a lingual bar, the lingual area should free and attached gingiva studied with the replica method. Oral. Surg. 5:649-655, 1955. have a minimum width of 4 mm keratinized gin­ 5. Borowik, D., Grabowska, M., Kaczynska, W., Karas, 38 39 giva. ' This requirement may be difficult to satisfy Z., Lembas, K., Lisiecka, K., Martyka, D., Mazurek, I., in the average patient since the mean width of the lin­ Ostrysz, W. and Pruchla, M.: Measurements of the width gual gingiva adjacent to the lower anterior teeth is of gums, the depth of epithelial attachments and oral ves­ usually less than 3 mm. tibule in children and adolescents. Czas. Stomat. 22:989- 994, 1969. It is apparent in periodontitis that pathologic pockets 6. Bernimoulin, J. P., Son, S. and Regolati, B.: Bio- metric comparison of three methods for determining the may easily extend beyond the mucogingival junction. mucogingival junction. Helv. odont. Acta 75:118-120, Although procedures have been devised for correction 1971. this problem when it occurs on the facial aspect, to 7. Coppes, L.: Routine-Sulcusdieptemetingen in de the best of our knowledge, modern periodontal surgery parodontologie. Het belong-de betrouwbaarheid-de toepass- offers no specific method for increasing the width of ing.