The Effects of Topically Applied Citric Acid on Periodontally Diseased Root Surfaces
The goal of reconstructive periodontal therapy is new connective tissue attachment to periodontally diseased root surfaces. Recently Register (1973) and Register and Burdick (1975) have reported accelerated reattachment and cementogenesis when citric acid was applied to surgically created root surface defects. There are apparently no reports in the literature regarding the effects of citric acid on periodontally diseased root surfaces. This study was designed to determine the effects of topically applied citric acid on periodontally diseased root surfaces using the scanning (SEM) and transmission (TEM) electron microscopes. Twenty three human teeth, nineteen extracted because of periodontal disease and four bicuspids extracted for orthodontic reasons, were used in this study. The teeth were divided into four groups: 1. orthodontic bicuspids (control), 2. periodontal disease without calculus, 3. periodontal disease with calculus removed, and 4. periodontal dis ease root planed. Each specimen was split and the experimental half of the tooth etched for three minutes with acid. The specimens were then analyzed with the SEM and TEM. SEM photos from adjacent control and experimental areas were evaluated for the presence or absence of five surface characteristics: 1. morphologic projections (pebbles), 2. depressions, 3. smooth flat areas, 4. ridges, 5. fiber-like structures (fibers). Differences were analyzed statistically using the paired Students "t" test. SEM results indicated that acid application produced significant differences only when applied to orthodontic bicuspids and root planed periodontally diseased specimens. It was ineffective when applied to periodontally diseased teeth that were not root plan ed. This is probably related to the hypermineralized zone which is characteristic of periodontally diseased root surfaces. When applied to root planed areas the acid produced a fiber-like surface with frequent depressions. With higher magnification (14000X) the entire surface appeared to be fiber-like. TEM observations showed that the fiber-like SEM surface was actually exposed collagen fibers. The acid produced a five micron demineralized surface zone which was dominated by exposed collagen fibers. These fibers were continuous from the mineralized to the demineralized portions of the root. The possible implications regarding connective tissue attachment to diseased root surfaces, of this collagen containing area are very exciting. With acid application we have produced a demineralized surface that may facilitate cementogenesis and new connective tissue attachment. In addition, this bed of exposed collagen fibers on the root surface may act in a manner similar to retained root surface fibers in reimplantation studies. In these experiments connective tissue attachment to retained root surface fibers has been a routine event, if the root surface fibers are unaltered. Whether acid demineralization does facilitate new connective tis sue attachment is a matter to be verified by further research. Nevertheless, acid application seems to produce root surface changes which are biologically compatible with predictable new attachment.
Periodontics and Periodontology, Periodontics -- methods
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