Clinical comparison of desired versus actual amount of surgical crown lengthening.

The actual length of clinically exposed tooth structure between planned restoration margin and alveolar crest ("biologic width") obtained during surgical crown elongation procedures was compared to the textbook goal of 3.0 mm. Sixteen (16) patients with 21 teeth requiring surgical crown lengthening for restoration placement participated. Oral hygiene instructions were given and optimal plaque control was mandatory. At each clinician's discretion, surgical techniques consisted of either gingivectomy or an apically positioned flap with and without osseous resection. Utilizing a reference stent, measurements were obtained at the facial, mesial-facial, lingual, and distal-lingual of the treated teeth both before and after osseous reduction. Parameters evaluated were gingival margin position, probing depth, mucogingival junction position, alveolar crest location, mobility, plaque index, and gingival index. These measurements were again recorded 8 weeks after surgery with the exception of alveolar crest. Statistical analysis with the paired t-test and linear correlation showed no significant change from baseline or among operators with varying experience in any of these parameters. Overall the results showed that the default objective of 3 mm between planned restoration margin and alveolar crest was not routinely achieved (mean 2.4 +/- 1.4 mm). The post-treatment distance from the planned restoration margin to the alveolar crest was greatest at the facial aspect of the teeth (mean 2.6 +/- 1.2 mm) and least at the distal-lingual (mean 2.2 +/- 1.7 mm). In addition, although more experienced periodontists removed a larger amount of bone, the amount of root surface exposed was still short of the initially desired biologic width.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparative study of vitreous carbon, pyrolytic carbon, pyrolytic graphite/silicon-carbide, and titanium implants in rabbit mandibles.

The purpose of the present investigation was to evaluate the biocompatibility of vitreous carbon, pyrolytic carbon, and pyrolytic graphite/silicon-carbide with rabbit mandibular tissues. Titanium was employed as the control material. Twelve New Zealand albino rabbits were implanted with each of the four materials described. Groups of four animals each were killed at 14 days, 45 days, and 90 days. Block sections containing the implants were then removed from the rabbit mandibles, and representative sections were evaluated histologically. All of the implants elicited similar reactions, including fibrous connective tissue capsule formation, multinucleated phagocytic cells, a mild inflammatory infiltrate, and reactive bone. On the basis of these findings, it appears that further detailed investigations are necessary to elucidate the biologic ramifications of the implantation of carbons in mammalian tissues.