ro o 1Ppr4( SVsT' r&cr( -too c The Development of the Permanent Teeth( CARMEN M. NOLLA, B.S., D.D.S., M.S.* T. is important to every dentist treat- in the mouth of different children, the I ing children to have a good under - majority of the children exhibit some standing of the development of the den- pattern in the sequence of eruption tition. In order to widen one's think- (Klein and Cody) 9 (Lo and Moyers). 1-3 ing about the impingement of develop- However, a consideration of eruption ment on dental problems and perhaps alone makes one cognizant of only one improve one's clinical judgment, a com- phase of the development of the denti- prehensive study of the development of tion. A measure of calcification (matura- the teeth should be most helpful. tion) at different age-levels will provide In the study of child growth and de- a more precise index for determining velopment, it has been pointed out by dental age and will contribute to the various investigators that the develop- concept of the organism as a whole. ment of the dentition has a close cor- In 1939, Pinney2' completed a study relation to some other measures of of the development of the mandibular growth. In the Laboratory School of the teeth, in which he utilized a technic for University of Michigan, the nature of a serial study of radiographs of the same growth and development has been in- individual. It became apparent that a vestigated by serial examination of the similar study should be conducted in same children at yearly intervals, utiliz- order to obtain information about all of ing a set of objective measurements the teeth. Therefore, an investigation of various physical and mental attri- was star ted,isirigPinney's technic, with butes. It has been found by Olson and some modifications. It seemed logkal to Hughes'6' 17, 18, 19 that there is an in- conduct such a radiographic study of the timate relationship in the functioning of development of the dentition, since ra- all the aspects of normal growth, as has diographs are used extensively in dental been shown by the plotting of a number diagnosis and clinical practice. Further- of measurements in the same graph. more, by means of serial radiographs When this relationship is appreciated, one can obtain continuous data on the one thinks of the development of the changes exhibited by the individual be- teeth, not as an isolated process, but as ing studied. one which relates to other developmen- Many investigators have studied the tal processes. development of the dentition by employ- So far, the only available measure of ing different methods of observation. dental age has been secured by noting These investigators should be recognized the eruption of teeth (Cattell). 5 Al- for their contributions because they have though the eruption of the teeth may facilitated further research. However, differ greatly in the time of appearance one still finds principles in the litera- ture that have not been explained sat- Formerly Assistant Professor of Dentistry, isfactorily and some misinterpretation of School of Dentistry, University of Michigan, Ann Arbor. Present address: 1408 Magdalena Ave., information. A review of the literature on Candado, Santurce, Puerto Rico. the development of the dentition shows 254 / 76 FOURTH QUARTER, 1960 255 that the technics and methods used 3. To prepare tables of development by Legros and Magitot,'l' 12 Black," 2 of permanent teeth which will permit Pierce, 20 Colyer, 7 B roomell and Fichclis,4 the interpretation of individual differ- Brady,3 Schour and Massler,22' 23, 24, 25 ences in dental growth, by the age-unit Logan and Kronfc-ld,'°' 14 and Mc- method; Call'4' 23 are inconclusive from, the point. 4. To gain information relative to the of view, of serial growth and develop- amount and kind of variation displayed ment of the individual as a whole. The by the growth 'of the permanent teeth; method most frequently used by these 5. To contribute to the understanding investigators has been the anatomic, his- of differences in dental development of tologic or radiographic study of autop boys and girls; sled material.. These methods of study 6. To reconstruct previous evidence, have a number of limitations. For in- with its errors in sampling and the omis- stance, with anatomic or microscopic sec- sions, into a theoretical set of develop- tions it is impossible to study the con- mental norms for permanent teeth from tinuity of growth in the same individual. beginning to completion; • According to Todd '26 "A dead. child is a 7. To make recommendations for fur- defective ` -.child in whom there has oc- ther study in terms of 'progress made by curred an interruption or prohibition of the current study. developmental growth sometime before It would appear that the information death, unless death is due to an acute derived would aid the dentist to assess disease or an accident, such as injury or and pace the development of a young burns. The interpretive study of actual person's dentition. Hence, .a meaningful skulls must be tempered by recognition concept, of normality, involving an in- of this fact. If we are to investigate dividual' growing child, might be se- healthy skulls, we must. do it on the liv- cured. ing." The,lmitation of the radiographic MATERIALS study is that the, developmental changes which occur prior to calcification are not The materials used for this :study con- sisted of "serial oral radiographs of twen- observed radiographically. On the other fv ty-five bo'ys' and twenty-five girls obtained c hand, a study of serial radiographs of from the files of the Child Development 5 the same individual provides, a good Laboratories of the University of Mich- method for the longitudinal study of ,igan School.. Each set of radiograph in- growth. cluded: This investigation, now to be report- 1. Extra-oral right and left lateral ed, was formulated in accord with, the jaws, following objectives: '2. Intra-oral maxillary and mandib- 1. To organize a technic for the de- ular occiusals, tailed appraisal of the development, of 3. 'Intra-oral right and left maxillary the permanent dentition as revealed by periapicals of posterior teeth. radiographs; These radiographs were' exposed and 2. To construct norms (tables and processed by the technicians in' the De- graphs) which will display the average partment of Radiography of the School development of individual teeth, both of Dentistry, University of Michigan. for boys and girls; Usually, a set of radiographs was secured 256 JOURNAL OF DENTISTRY FOR CHILDREN for each year of the record at a time Not all of the long series were used. were approximating the individual's birthday. The radiographs were placed on a spe- that t] The total number of radiographs for the cial view table which permitted accurate ly the girls was 1746 and for the boys 1656. reading of details. The observation took is in a The range in age of the group studied cognizance only of the degree of develop- in his is shown in Table I. ment, as outlined in Figure I, which is can b a set of drawings illustrating the ten are re TABLE I stages of development of the teeth as ob- the te RANGE IN AGE served radiographically. The first column dil)Ie. (right) appraises the growth-stage of the the ol Beginning Terminal Age in Age in central and lateral incisor, the second peatin Sex Months Average Months Average the cuspid, the third the bicuspids, and In Girls 25- 80 55.3 141-279 198.2 the fourth the molars. The drawings il- the d4 Boys 41-121 68.3 163-277 201.8 lustrate for each of the ten stages (1 to the r2 10 inclusive) the appearance of the stage as pos METHOD of dental development observed radio- For e The radiographic records were select- graphically. were ed from the files on the basis of length. Although both right and left sides given root ' grade 10. APICAL ENVOY ROOT COMPLETED iiig la' was in ample . S 9. ROOT ALMOST COMPLETED OPEN APEX ilj were of the . TWO-THIRDS OF ROOT COMPLETED... VLIUC showe 7. ONE-THIRD OF ROOT COMPLETED er tha much the fl( . CROWN COMPLETED e am1 of the 5. CROWN ALMOST COMPLETED l,ecorr, one-th 4. TWO-THIRDS OF CROWN COMPLETED grade 1.1 tent 3. ONE-THIRD OF CROWN COMPLETED i.iitlica examl appro. 2. INITIAL CALCIFICATION () 0 0 0 Q Q Q Q would root i 0 0 00 0000 1. PRESENCE OF CRYPT would Tlim 0. ABSENCE OF CRYPT difhcu FIGURE 1. Stages of development of mandibular and maxillary teeth. LIC, as FOURTH QUARTER, 1960 257 re used. were observed and studied, it was found the growth-level, half-way between the )fl a spe- that the rate of growth was approximate- growth-stage, and close to the next level. accurate ly the same in both sides. This finding Attempts to appraise radiographs more ;ion took is in agreement with Pinney's experience accurately than this grading do not develop- in his earlier investigation. As a rule, it seem feasible. which is can be said that the values for one side A detailed description of the changes the ten are representative of the development of in developing teeth as observed radio- th as ob- the teeth of the maxilla and the man- graphically now will be described. In de- •t column dible. In all of the radiographs studied termining the amount of maturation of ge of the the observations were controlled by re- developing teeth, the marginal appear - e second peating the observation a second time.