The following clinical study was conducted in order to evaluate and compare the long term (2-30 yr) clinical effects of subgingival placed crown margin in areas of narrow < 2.0 mm and with >2.0 mm zones of keratinized gingiva.
A total of 58 teeth in 28 patients were evaluated in this study. Age 23- 80 yr. Teeth were divided into two groups. Group I had a width of keratinized gingiva equal to or greater than 2.0 mm and Group II had less than 2.0 mm. These groups were further subdivided into two subgroup exp. or cont. according to the presence or absence of a full coverage subgingival restoration. Experimental teeth criteria. Subgingival margin, clinically acceptable, must be in place for at least 2 years. Measurements- PlI, GI, PD < BlI, Width of Keratinized Gingiva, Width of Attached Gingiva, Attachment Level, Bone Level. The mean length of time 4.5 yr.
Comparing the two groups I and II, in the control group. The mean width of attached tissue was 2.47 mm in group I and 0.19 mm in group II. Bleeding on probing in group I 26.7%, in group II 40.0%
Comparing groups I and II, in the experimental group. The mean width of attached tissue was 2.13 mm in group I and 0.16 mm in group II. A mean gingival score of 1.73 for group I, and 2.27 in group II. 86.7% in group I bled on probing, and 93.3% in group II bled.
A subgingival restoration, the degree of gingival inflammation in significantly greater in association with narrow zones of keratinized gingiva than with those greater than 2.0 mm. While nonrestored teeth with either wide or narrow zones showed no significant difference. The increase in gingival scores from restored teeth to nonrestored teeth in the present study was expected.
In patients scheduled to receive subgingival restorations where narrow zones of keratinized gingiva exist, and who cannot maintain optimal plaque control levels, it may be desirable to increase the width of keratinized tissue.
Problem with study was the lack of number of teeth, and the lack of pre-op measurements.
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