to make the information noticeable to the maximum extent the microdot designated 30 is placed in the bottom of the recess in tooth t prepared by the foregoing procedure in the manner shown in fig7 e g by use of a pipette or probe whereafter the recess is filled and the microdot is covered by a light curing transparent bonding medium 31 e g the product 34 heliobond 34 distributed by vivadent u s a inc of tonawanda n y the bonding medium cures quickly e g in about 30 seconds completing the operation in view of the extremely small size of the chip the data on the chip cannot be read by the naked eye but has to be read under magnification the use of a conventional optical instrument for such reading is cumbersome since the subject 39 s head must be held steady for an appreciable length of time to allow the data to be read in contrast to prior art techniques therefore the present invention contemplates that the data on the microdot will be retrieved by use of a camera which is operative to magnify and photograph the microdot thereby to provide an enlarged image which can be read by the naked eye and which at the same time provides a permanent record of the microdot information to simplify the retrieval of information and to obviate the need to make adjustments in the camera at the time the microdot is photographed the camera utilizes a lens of predetermined fixed focal length the depth of the tooth recess achieved by the aforementioned steps having been selected to assure.