Harald A.B. Linke

Black tea extract and dental caries formation in hamsters

Several studies have suggested that green tea and Oolong tea extracts have antibacterial and anticariogenic properties in vitro and in vivo. The aim of the present study was to determine the effect of a standardized black tea extract (BTE) on caries formation in inbred hamsters on a regular and a cariogenic diet. Eighty hamsters were divided into four groups of 20 animals each. Two groups received a pelleted regular diet (LabChow) with water or BTE ad libitum. The other two groups received a powdered cariogenic diet (Diet 2000, containing 56% sucrose) with water or BTE ad libitum. The animals were kept for 3 months on their respective diets and then were sacrificed. The heads were retained, the jaws were prepared and stained using alizarin mordant red II, and were then scored for dental caries according to the Keyes method. This is the first study indicating that BTE, as compared with water, significantly decreased caries formation by 56.6% in hamsters on a regular diet and by 63.7% in hamsters on a cariogenic diet (P < 0.05). In the cariogenic diet group BTE, reduced the mandibular caries score of the hamsters slightly more than the maxillary caries score. The fluoride content of the standardized BTE solution was frequently monitored during the experiment; the mean fluoride concentration was found to be 4.22 ppm. A frequent intake of black tea can significantly decrease caries formation, even in the presence of sugars in the diet.

Effective surface sterilization of gutta-percha points

A bacteriologic investigation was conducted to determine the sterilizing effectiveness of various germicidal endodontic irrigants on gutta-percha points. It was found that most effective in surface sterilization was a 5-minute treatment using sodium hypochlorite, Zephiran, and hydrogen peroxide in concentrations of 4.50 percent, 0.53 percent, and 3.00 percent, respectively. These agents were potent against gram-positive and gram-negative bacteria as well as endospore-forming microorganisms. Fungal spores were killed only by the first two but not by the latter germicidal agents. On the other hand, ethanol, chloroform, eugenol, betadine, and Grams iodine solution were found not to be effective for surface sterilization.

Clinical survey of Entamoeba gingivalis by multiple sampling in patients with advanced periodontal disease

A clinical survey of Entamoeba gingivalis was conducted in patients with advanced periodontal disease. A total of 100 specimens were taken from 10 patients (four females and six males) who were each sampled at 10 disto-facial random sites. The oral hygiene of the persons scored from good to fair to poor and very poor. The age of the test persons ranged from 20 to 68 years. All persons examined harbored E. gingivalis: the minimum prevalence was four sites positive out of 10 and the maximum prevalence was 10 sites positive out of 10 for the protozoan. It is recommended that for reliable testing of the presence of E. gingivalis at least five-10 different sites should be examined within the periodontium of each patient. Data reported earlier in the literature on the incidence of E. gingivalis--obtained after a single sampling per individual--are believed to be on average too low and, therefore, should be interpreted with caution.

Quantitation of catecholamines in inflamed human dental pulp by high-performance liquid chromatography.

Catecholamines may play an important role in the control of intrapulpal pressure as mediators of vasoconstriction. A baseline level of catecholamines (dopamine, epinephrine, and norepinephrine) in the uninflamed human dental pulp was previously reported using high-performance liquid chromatography. The purpose of this study was to compare the level of catecholamines present in the inflamed human dental pulp with the baseline level established in virgin teeth. Twelve uninflamed pulps were analyzed as a control and to validate previous findings. Pulp tissue was obtained from 10 vital and inflamed teeth requiring endodontic treatment. Selective criteria for each patient included: absence of systemic disease, medications, and allergies; a vital response to ice, heat, and electric pulp tests; and periodontal probing < or = 3 mm. A prior history of pain associated with the tooth was an additional criterion for inflamed pulps. To avoid the presence of an exogenous catecholamine, local anesthesia without epinephrine was administered. Dopamine, epinephrine, and norepinephrine were chemically extracted and analyzed by high-performance liquid chromatography with ultraviolet detection. Catecholamine levels found to be present in the pulp during inflammation were greater than the baseline level established in uninflamed pulp tissue.

Quantitation of catecholamines in uninflamed human dental pulp tissues by high-performance liquid chromatography

The quantitation of catecholamines has yet to be reported in the human dental pulp. Various methods of chemical detection have shown the presence of catecholamines in pulpal tissue. Pulpal tissue was obtained from nonrestored, uninflamed teeth that needed to be extracted. The samples were collected, extracted, and analyzed by means of high-performance liquid chromatography with ultraviolet detection for levels of catecholamines (dopamine, epinephrine, and norepinephrine). As mediators of vasoconstriction, catecholamines play an important role in the control of intrapulpal pressure. This research describes a method for quantitation of catecholamines. Future studies investigating inflamed tissue can now be accomplished with the use of this analytic method. The results from this research indicate a baseline level of catecholamines in the uninflamed human dental pulp.

Growth studies on xenic cultures of Entamoeba gingivalis using established media

Wantlands egg medium, modified Shaffer-Frye (MSF) medium and Tryptose-Trypticase-Yeast Extract-Serum-Blood (TTY-SB) medium were compared with variations of the latter two media for their ability to support xenic growth of Entamoeba gingivalis. Wantlands egg medium was unsuitable for growth of E. gingivalis. Accompanying bacteria became resistant to penicillin and streptomycin, overwhelming the amoeba culture. MSF medium was also unsuitable for the cultivation of E. gingivalis. Bacterial growth was heavy and protozoan growth sparse. MSF medium without mercaptosuccinic acid, but with rice starch, dextran or levan substituted for glucose and with Yersinia enterocolitica added, supported limited growth of the amoeba. Unmodified TTY-SB medium did not sustain growth of E. gingivalis. However, when rice starch suspension was substituted for glucose, L-cysteine HCl was deleted, and a Crithidia sp. was added to the E. gingivalis culture grown xenically, enhanced growth of the oral amoeba resulted in this modified TTY-SB medium. E. gingivalis is very sensitive to changes in incubation temperature. Optimum growth was found to be in the narrow range from 34.5 to 35 degrees C for all media tested.

Microbiological composition of whole saliva and caries experience in minority populations

Microbiological factors in whole saliva, previously implicated in dental caries formation, were studied in four caries-positive adult ethnic groups: Asians, blacks, whites, and Hispanics. Whole saliva was collected from each patient and used for the enumeration of total cultivable microflora (T), streptococci, mutans streptococci (MS), and lactobacilli. In the female subgroup, statistically significant differences were found among the ethnic groups with regard to T in saliva. In the male subgroup, statistically significant differences were found among the ethnic groups with regard to MS in saliva. Statistically significant differences were also found among the ethnic groups in relation to caries score (DMFS), with the Hispanic group having the highest mean DMFS score; and among socioeconomic groups with regard to MS in saliva. Moreover, microbial composition (T and MS) of whole saliva and DMFS scores differed significantly (P < 0.05) among the ethnic groups studied.

Synergistic growth studies of Entamoeba gingivalis using an ecologen.

A unique multiple diffusion growth chamber, an Ecologen, designed for the study of interactions among microorganisms, was introduced as a means of growing xenic cultures of Entamoeba gingivalis with Crithidia sp. or Yersinia enterocolitica. Entamoeba gingivalis was grown in the central diffusion reservoir of the Ecologen connected to separate growth chambers inoculated with the microorganisms to be evaluated. Growth of the accompanying bacteria in the E. gingivalis compartment was almost completely eliminated, except for sparse Pseudomonas sp. growth. The most vital E. gingivalis cultures were observed when either Crithidia sp. or Y. enterocolitica were added to the Ecologen 48 h prior to the E. gingivalis inoculum. The medium which provided the best growth of the oral protozoan in this system was the new improved E. gingivalis medium containing antibiotics.

An antibiotic-free medium for the xenic cultivation of Entamoeba gingivalis

Diamonds TYI-S-33 (Trypticase-Yeast Extract-Iron-Serum) medium was used as the basis for a new antibiotic-free medium for xenic growth of Entamoeba gingivalis. Nutritional requirements of the oral protozoan were determined in an effort to optimize growth. TYI-S-33 medium did not support E. gingivalis growth prior to modification. The changes included: (a) deletion of L-cysteine.HCl and thioctic acid, (b) substitution of glucose for dextran I (mol. wt 185,000) or rice starch, (c) reduction of concentrations of tryptone (2.5 g l-1), yeast extract (1.25 g l-1) and dextran I (1 g l-1), (d) increased concentration of ferric ammonium citrate (0.2 g l-1), and (e) addition of gastric mucin (2.4 g l-1). Dextran I was chosen as the major carbon source; its use in the medium limited growth of accompanying bacteria. This new antibiotic-free medium significantly increased E. gingivalis growth (16-20 E. gingivalis trophozoites observed per field) as compared to growth in Diamonds TYSGM-9 (Trypticase-Yeast Extract-Serum-Gastric Mucin) medium (six to 10 E. gingivalis trophozoites observed per field).

A new medium containing antibiotics for the xenic cultivation of Entamoeba gingivalis.

Diamonds trypticase-yeast extract-serum-gastric mucin (TYSGM-9) medium was studied for its suitability to support the xenic growth of the oral protozoanEntamoeba gingivalis. Amoebic growth was found to be best when the inoculum for transfer was 0.1 ml, the incubation temperature was 35°C, and the interval between transfers was 48 h. These parameters were also useful for controlling the growth in xenic stock cultures, In addition, bacterial growth in xenic stock cultures, which had a direct effect on the activity ofE. gingivalis trophozoites, was kept to a minimum by addition of the antibiotics piperacillin, erythromycin, neomycin, and penicillin. Varying substitutions and selected supplementations of TYSGM-9 medium led to the development of an improved medium forE. gingivalis. Supplements most beneficial for the growth ofE. gingivalis trophozoites were ascorbic acid, ferric ammonium citrate, and special NCTC 107 vitamin mixture. As compared with TYSGM-9 medium (6–10E. gingivalis trophozoites observed per field), the newE. gingivalis medium supported excellent growth (16–20E. gingivalis trophozoites observed per field during optimal growth) of the oral protozoan. The medium is suitable for clinical isolation ofE. gingivalis.