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information regarding the details of gingival repair following gingivectomy. The demonstration of the applicability of the Warburg technic8 for the determination of the oxygen consumption of normal and inflamed gingiva suggested an additional approach to the subject of gingival repair. A correlated study of oxygen consumption and histological changes in the course of gingival healing was undertaken, therefore, in an effort to augment existing knowledge by revealing an additional aspect of the gingival repair process.

IT HAS B E E N DEMONSTRATED that the chloromethyl analogue of Victamine C , t an inhibitor of crystal seeding of calcium phosphate in calculus smears in vitro, 1 reduces calculus formation intraorally on Mylar strips tied to mandibular incisors. To rule out the possibility that the taste of the chemical may have influenced its effect on calculus formation by stimulating salivation or mechanical action of the tongue against the Mylar strips, a study was conducted comparing it with quinine sulfate for its effect on calculus formation on the teeth. Quinine sulfate has a similar taste, but does not inhibit crystal seeding of calcium phosphate in vitro.

Five straight-chain homologs of chlorhexidine, containing from two to 12 methylene groups, were synthesized and evaluated along with chlorhexidine for in vitro antiplaque activity. Maximum antiplaque activity was exhibited by the compounds containing six (chlorhexidine) and 12 methylene groups.

A microscopic study was made of the crystallization of calcium phosphate on calculus in vitro and its inhibition by certain chemicals. To induce crystallization, human calculus was smeared on microscopic slides. These were incubated in a physiologic metastable calcifying solution and stained with haematoxylin and eosin. Needle and rod shaped crystals formed about central calculus particles after 24 hr and increased in amount during a 6-day experimental period. Octacalcium phosphate was identified in the crystals and the calculus by X-ray diffraction analysis. Neutral solutions of the following were screened for their capacity to inhibit crystal seeding by the calculus: distilled water, magnesium chloride, ammonium oxalate, barium chloride, nickel chloride, sodium stearate, sodium tartrate, glycerine, sodium-β-glycerophosphate, thiamine pyrophosphate, adenosine diphosphate. Crystal seeding by the calculus was inhibited by sodium-β-glycerophosphate, thiamine pyrophosphate, and adenosine diphosphate, when employed both as a pretreatment for 24 hr and as a mixture with the calcifying solution. Crystallization was not affected by pretreatment with the other chemicals.

Primary explants from human gingiva, lip and palate were cultured in vitro from male and females 6–69 years of age. Cultures were maintained from 1 week to 4 months and were stained for acid and alkaline phosphatase and acid mucopolysaccharides. No significant differences were noted in the rate or type of outgrowth or staining characteristics from different areas of the mucosa and in the different age groups. Sex differences were not demonstrated morphologically or histochemically.

Exposure of male albino rats to temperatures of 0 to 2° C. for two weeks resulted in osteoporosis of alveolar bone, characterized by decreased osteoblastic activity and periodontal membrane changes consisting of decreased cellularity and granularity of the collagen. With continued exposure, the changes in the periodontium diminished in severity. There was evidence of changes after four weeks, but after four months the periodontium returned to normal.

SummaryAn epithelial-like cell line has been established from an area of clinically normal adult human attached gingiva, It has a generative time of approximately 24 hours in logarithmic phase and a plating efficiency of about 80-90%.