The pathogenesis of reduced mandibular dimensions and asymmetry was studied in 103 patients with juvenile rheumatoid arthritis. Abnormalities of the temporomandibular joint were intimately related to mandibular growth disturbances. Unilateral joint abnormality resulted in jaw asymmetry and underdevelopment on the affected side. Duration of disease and of corticosteroid therapy, age at disease onset, and age when the data were recorded were correlated with the size of the mandible. Our findings did not support a hypothesis of cervical spine involvement as an etiologic factor of reduced mandibular size.

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The design and mode of operation of a digital read-out system for rational measuring of radiographic headplates and dental models is described and the advantages and disadvantages of the instrument are discussed. The instrument allows direct reading of linear and angular measurements and of coordinates in a freely chosen coordinate system to a resolution of 0.1 mm and 0.1 degree. The instrument is connected to a teletype writer that can reproduce the results as hard copy print-outs and as punched paper tapes. Data can be transferred directly from the paper tapes to a computer for storage or calculation. Additionally the teletype can serve as a computer terminal with optional connection on-line with a computer. In the conventional method of compiling data from radiographic headplates error can arise from landmark identification, tracing, measuring and recording. In the transfer of data to a computer the punching is another possible source of error. With the instrument described in this report, provided that it is in order and correctly operated, there is only one source of error, namely landmark identification. The instrument is time-saving and simple to use. For clinical purposes direct measurement of linear and angular dimensions is the most rational approach but, in research, coordinate registration offers considerable advantages in that all parameters regularly used in roentgencephalometrics can be calculated by a computer on the basis of the coordinates of a relatively limited number of landmarks.

– The present study investigated whether the incidence or prevalence of filled teeth/ approximal surfaces at one age could be predictive for the incidence in another period or for the prevalence at the age of 18. The study was conducted in 12–18‐yr‐olds in Norway. Regression analysis showed that the best prognosis for subsequent incidence of filled teeth/approximal surfaces could be made at the age of 15. By using regression analysis or discriminant analysis it was possible at the age of 15 to predict with high accuracy those who would acquire more fillings than the median at the age of 18. Discriminant analysis with one predictor variable is suggested for clinical use. The variable that discriminated best between above and below median number of new fillings in the period 15 18 yr was untreated lesions in the inner half of the enamel in the approximal surfaces of premolars and molars at the age of 15. From the use of simple prediction tools, it was concluded that individuals at the age of 15 with a low prevalence of filled teeth/filled approximal surfaces and without untreated approximal lesions would be subjected to a low incidence of new fillings until the age of 18.