Gerald J. Cox

Effects of Food Acids on Human Teeth in Vitro

Many studies have been made comparing the effects of acids on human teeth with varying results. To clarify what happens to the enamel of teeth, three food acids and two liquids commonly consumed by humans were tested. A 0.055% solution of phosphoric acid (the concentration in a cola beverage) a 0.1 M solution of citric acid (simulating orange juice), and a 0.05 M solution of oxalic acid (representing spinach and some other vegetables) were used. Also included were a cola beverage and orange juice. Human teeth were cut in half vertically with a Gillings-Hamco thin sectioning machine. The plane of sectioning was chosen to provide similar sections for each half. A fine blade was used so that a minimum amount of material was lost in the process. To duplicate the conditions in the mouth more closely it was necessary to coat the root area of the teeth with paraffin. This left only the enamel exposed to the acid. A different color paraffin was used for each of the test solutions as a means of identification. Half of each tooth was then placed in 15 ml of distilled water in a 25 ml stoppered tube and the other half in 15 ml of the acid solution being tested. Eight pairs were tested because the probability of all eight being equally affected by the acids, on the null hypothesis, is 1/256 or 0.0039. Five solutions were used and this meant 40 teeth or 80 halves.

Effects of Physical Character of Diet on Tooth Emergence Time of Third Molar Tooth of the Rat

Although tooth emergence is only one incident in the process of eruption, the time of emergence varies widely and may be retarded or accelerated by systemic factors, such as race, nutrition, body growth, and heredity, biological functions, as well as local factors. The purpose of this study was to investigate the possible stimulatory effects of the physical character of diet on tooth emergence time. The birth of the rats used in this study was ascertained within an 8-hour period. Thirty-eight male rats of the Long-Evans strain 21 days of age were utilized. An experimental group of 19 animals was placed on rat diet whole pellets,

Punched-Card Recording of Carious Lesions of Both Dentitions of Man

while an equal number were given pellets ground by the local supplier. These diets were the only food supplied throughout the course of the experiment. All animals were fed and watered ad libitum. At approximately 31 days, the animals were observed every 8 hours for evidence of emergence of the maxillary right third molar. This examination procedure was aided by a fine dental explorer (No. 17) and an otoscope with a 5-mm. spectrum.§ Tooth emergence time was recorded in 8-hour units and calculated from the birth time. The mean emergence time for the third molars of the group on whole pellets was 103.24 eight-hour units or 34.41 days, while the molars of the ground pellet group was 103.55 eight-hour units or 34.52 days. These data indicated no significant difference between the emergence times of the maxillary right third molars of the wholeand ground-pellet diet groups.

Effects of the physical consistency of diet on the condylar growth of the rat mandible.

This report is concerned with a method of reducing individual dental records to a form, namely, a single punched card of the Hollerith type that permits (1) the ready analysis of a population for simple frequency of various attack on any surface of any of the primary and permanent teeth of man, (2) study of association of decay of any groups of 2 or more dental areas, and (3) study of frequency of and associations of other oral conditions. In order to record all of the data of caries in 52 teeth as well as to give description of the subjects and other oral conditions on a single card, the following principles have been used: