A Study on the Illumination of Dental Surfaces

Abstract

Although there is much published literature on lighting equipment in the dental field, studies on the illumination in this field are scanty. In the present study, the author was concerned with the measurement of illuminative degrees on the surfaces of individual teeth by directly introducing photoconductive cells into the mouth of a subject. Along with the measurement of illumination on the teeth, efforts were also made to find out how much contribution would be made by the dental mirror by way of promoting the dental surface illumination.For experimental purposes, a complete denture was constructed with 16 photoconductive cells embedded on the distal, lingual and buccal sides 6, labial side of 1, lingual side of 1, occlusal surfaces of 4 5 6 7 distal, lingual and buccal sides of 6, occlusal surfaces of 4 5 6 7. This experimental denture was installed in the mouth, so that indices of the photoconductive cells on the illuminative surfaces would be measured and the indices were subsequently converted numerically by the illuminometer. A subject was instructed to sit in a dental chair and light was projected from three directions: the occlusal surface of the upper jaw (A), the occlusal surface of the lower jaw (C), and midway between the two (B). At the same time, three positions of 20° right of the median line (X), median line (Y) and 20° left of the median line (Z) were established. Therefore, light was be projected from each of these nine directions.As a result of these comprehensive efforts, the author arrived at the following conclusions.1) Under direct light at the different positions, the degree of illumination increased in the order of A, B and C with the upper jaw; the highest degree was registered on the labial surface of the central incisors and the lowest was on the distal surface of first molars. The lowest was on the distal surface of the first molars at a position of CX, the latter corresponding to only 0.1% of the former.2) With the exception of a 19mm dental mirror for the distal surface of the upper and lower first molars, dental mirrors with larger diameter were found to be more efficient. A dental mirror of much larger diameter, devised for the purpose of this study, was quite efficient.3) All of the commercial dental mirrors failed to come up to the Japanese Industrial Standards in the rate of light reflection.4) Although a dental mirror of small diameter had a large reflecting rate, mirrors of larger diameter had correspondingly large reflecting rates on the whole.5) In separating colored rice grains by subjects inexperience with dental mirrors, the 19mm mirror was found less efficient than the 35mm mirror and, when a mirror of smaller diameter was used, more sense of fatigue was complained of. The result was more or less the same with dentists. The illumination of 34000 lux was very efficient. The fact that the 35mm mirror was very efficient was also endorsed by the findings of a flcker test.6) In a test where Landolt rings were used, the findings were also in favor of the 35mm mirror and 34000 lux. From these facts, it was found that the efficiency differed according to the diameter of dental mirrors and projecting rates.7) In a group dental examination, it was found that working efficiency and accuracy of the diagnosis were definitely influenced by the diameter of the dental mirrors used.