John Afflitto

Crystal Growth of Hydroxyapatite In Vitro and Dental Calculus and Plaque Formation on Human Teeth In Vivo

Sodium polyvinylphosphonic acid (SPVPA) was synthesized using vinyl phosphonyl dichloride and azobisisobutyronitrile (AIBN) as a radical initiator. The homopolymer obtained was characterized by molecular weight, purity and impurities by using gel permeation chromatography and NMR. The pure polymer was used to assess the influence on crystal growth kinetics of hydroxyapatite (HAP) in vitro. Briefly, the experimental solution supersaturated with respect to hydroxyapatite (HAP) was prepared from stock solutions of CaCl2, K2HPO4, KH2PO4, and NaCl. The crystal growth was initiated by adding pure seeds of HAP at 37 °C. The precipitation kinetics was followed using a pH-stat and measuring calcium phosphate in the solution. The effect of the polymer on the crystal growth kinetics was assessed, and it was found that the polymer inhibited the growth at 10−5 M. The inhibitory effect of the polymer was related to its adsorption onto the growing crystals. The adsorption parameters were derived from an adsorption isotherm-yielding a K value of 1,950 m1/mM and the N value of 0.038 mM/m2. A topical application of 1% solution of the polymer onto teeth was effective in reducing calculus formation by 18% in rat model system. SPVPA was also very effective in reducing adsorption (>90%) of radiolabelled bacteria, Streptococcus mutans, and Actinomyces viscosus, onto saliva-coated hydroxyapatite beads and disks. The polymer was also tested in short-term human clinical studies and showed that 1% and 3% solutions significantly (P = 0.05) reduced bacterial plaque film on teeth by 21 to 36%, respectively. Collectively, the data indicated that the sodium polyvinylphosphonic acid has the potential to prevent soft and hard dental deposits on teeth.

113Cd Nuclear Magnetic Resonance (NMR) Study of the Inhibitory Effect of Methylvinylether/Maleic Acid (PVM/MA) Copolymer on the Alkaline Phosphatase of Escherichia coli

The inhibitory effect of PVM/MA copolymer on the alkaline phosphatase (AP) of E. coli was investigated. Kinetic studies indicated that enzyme inhibition was characterized by a reduction in both the Vmax and the Km. Addition of 1 mM zinc or magnesium ions to the reaction prevented inhibition of the enzyme by the copolymer. The inhibitory effect of the copolymer on alkaline phosphatase was also investigated using 113Cd NMR after exchange of the active center metal ions with 113Cd. The resulting Cd(II)6AP exhibited characteristic 113Cd resonances reflecting the environment of the A, B, and C metal binding sites of the enzymes active center. Addition of copolymer resulted in a 113Cd NMR spectrum which indicated removal of 113Cd from the C site and formation of two distinct forms of the enzyme. Possible explanations for the 113Cd NMR results are discussed.

Recent Advances in Dentifrice Technologies

Dental diseases including cavities (caries), tartar (calculus), sore gums (gingivitis), and periodontitis (loss of tissue supporting the teeth) are worldwide problems. The annual cost of all dental care in the U.S. exceeds

Antiplaque antibacterial oral composition

37 billion,1 out of which roughly

Antibacterial antiplaque anticalculus oral composition

6 billion is spent to repair the ravages of decay. However, the cost of dental disease cannot simply be measured in monetary terms. Other factors also need to be considered; for example, the loss of teeth leading to impaired chewing ability, speech problems, and changes in facial aesthetics which can cause embarrassment. The well-being of a person may also be compromised due to the associated dental pain, inability to chew properly, and potential of the infection spreading from the mouth to other parts of the body.