Wendell L. Wylie

Mixed dentition case analysis-estimating size of unerupted permanent teeth

Abstract 1. 1. The amount of harmony between groups of human mandibular teeth with respect to mesiodistal width is indicated by coefficients of correlation. 2. 2. From the coefficients of correlation there has been derived a predictive graph which makes it possible for one, knowing the sum of the mesiodistal widths of the four mandibular incisors to arrive at the total sum of the mesiodistal widths of the mandibular canine, first premolar, and second premolar of one side. 3. 3. The average error found to arise from the use of this predictive graph was 0.6 mm., or 2.6 per cent. In the same group of cases, using measurements taken from models of the permanent dentition as the correct values, the average error arising from the use of intraoral dental films of average quality taken in the mixed dentition was found to be 2.2 mm. or 10.5 per cent. 4. 4. The predictive graph will give only the sum of the unerupted teeth of one side in the mixed dentition, and does not provide an estimate of the mesiodistal width of any one of the three teeth. As such it is offered as an adjunct to the method of the mixed dentition diagnosis and case analysis of Nance.

The Naso-Meatal Line as a Guide for the Determination of the Occlusal Plane

In determining the level of the occlusal plane in complete denture prosthesis, dentists commonly accept as a guide a line connecting the tragus of the ear (sometimes the auditory meatus) and the ala of the nose, making the occlusal plane of the denture parallel with this line in the lateral aspect, and parallel in the frontal aspect with a line connecting the pupils of the eyes. Reliance upon this naso-meatal line is based upon a considerable number of years of clinical observation; in practice it serves only as a point of departure and is not rigidly binding, i.e., articulation and balance of the artificial teeth ultimately play a larger part in the final determination of the occlusal plane. Wilson (1) and Anthony (2) recommended the guide without comment, while Prothero (3) and Swenson (4) mentioned it but pointed out that it is variable and that other factors enter into the determination of occlusal level. Schlosser (5) suggested a line from the base of the nose to the center of the head of the condyle. The true usefulness of this guide depends upon two things: whether or not in a representative group of adults having a natural dentition the occlusal plane parallels this line on the average, and whether or not most of the individuals in the group adhere closely enough to the average value to accept that average as a reliable guide. This study was undertaken to test the usefulness of the clinical rule by determining a quantitative measure of this average and its variability, and to determine what age changes, if any, must be considered. Fifty-five individuals (22 parents and 33 offspring) were radiographed in the Broadbent-Bolton cephalometer in the Department of Orthodontia, College of Dentistry, University of Illinois, and the lateral head-films so obtained were traced and studied. The convention of treating all points in the lateral headfilm as projections to the median sagittal plane was used; when this was done, all bilateral points were treated as single points situated in the midline, and planes became lines lying in the median sagittal plane. The anthropometric plane, proposed by Petrus Camper in 1786, which passes through the center of the external auditory meati and the anterior nasal spine was taken as a bony appr9ximation of the naso-meatal guide line; on the tracings it was necessary to use the superior surface of the ear-rod for the posterior point. The occlusal plane was determined on each tracing by drawing a line through the incisal

Orthodontic education, certification, and licensure

Abstract The place of orthodontics in the undergraduate curriculum may be more sharply defined when other departments in the school give fuller recognition to certain biologic fundamentals. This can be achieved by allotting more time to basic material in the curriculum, and by integrating those concepts with clinical teaching. This would relieve the orthodontist of teaching subject matter which they must now cover if students are to get it at all. Orthodontics would then be presented for what it is—a complex clinical field which involves specialized training and skill—a line of endeavor which the general practitioner cannot hope to practice, but one with which he should have more than a casual acquaintance. The Preventive Curriculum at the University of California has shown itself to be an effective program for training specialists in orthodontics, even though the original intention of its sponsors were somewhat different. The plan has distinct advantages over the usual graduate or postgraduate course taken after the dental degree has been won; not only do the students have a longer period of contact with patients under treatment, thus seeing a higher percentage of cases through to completion under supervision, but they also have a longer period of time for mulling over problems and establishing close rapport with instructors. Certification of dental specialists by qualified boards has had an auspicious beginning, and its rapid growth in the immediate future may be expected. The mutual interest of established diplomates, prospective diplomates, and educational institutions must receive careful consideration in the coming years of rapid expansion. Because the boards and the specialties which they represent secure their strength primarily from the respect they can command, wielding no police power, they may expect a certain amount of harassment from those who are specialists by declaration only. In localities where the irresponsibilities of pretenders threaten the public welfare and the reputations of properly qualified men, state licensure for specialists should be considered. This is a dismal recommendation to make when there seem to be more than enough laws already, but grave ailments sometimes require strong medicine.