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Development of the deciduous dentition
Am. J. Orthod. February 1983
176 Reviewsand abstracts 2. The mandible demonstrated significant forward and upward displacement, associated with rotation. 3. The condylar cartilage gained in thickness with increased growth of the condyle on the ninetieth day but returned to normal by day 180. The reaction was considered to have a certain saturation point, rather than being linear. 4. Morphologic changes in the condyle were seen with resorption on the anterior border of the condylar neck and deposition on the posterior border. 5. The mandibular angle was opened by pronounced bone deposition on the posterior ramal border and bone resorption on the inferior mandibular border. 6. The coronoid process demonstrated a backward and upward morphologic change, with resorption on the anterior border and marked deposition on the posterior border. 7. The postglenoid tubercle showed mesial drift and morphologic changes with deposition on the anterior border and resorption on the posterior border. 8. Changes were observed in growth direction of the maxilla. 9. Forward traction on the mandible influenced not only the maxilla but the zygomatic, temporal, and sphenoid bones. T. M. Graber
Thesis abstracts Development
of the Deciduous
Dentition
Marjatta NystrC)m University
of Helsinki,
1982
This academic dissertation is roughly equivalent to a doctoral dissertation in the United States, albeit the work can be done and parts can be published in periodical literature before the final compilation and defense. Five publications serve as the basis of this work. The aim of the investigation was to study formation of maxillary deciduous incisors and canines and mandibular deciduous molars from the age of 6 months onward. In addition, clinical eruption of deciduous teeth and dimensions of dental arches, spacing, and occlusion during the complete deciduous dentition were studied. The longitudinal investigation was started in 1967. Of the 382 first-born children who started the project, 214 were still part of the study at the 5-year examination. Fifty-three siblings joined the project, making a
total of 267. By 1981, the sample size was 185, with subjects ranging in age from 7 to 13 years. Clinical, radiographic, and cast data were compiled and subjected to biometric evaluation. The investigation of tooth formation was cross sectional; the balance of the study was longitudinal. The results are summarized as follows: All deciduous teeth studied showed completion of crowns by the age of 1 year. At 3 years all teeth studied, except the mandibular second molar, had complete root development. No sexual dimorphism was noted. The tooth-emergence study was based on data compiled by the mothers. The mean age at eruption of the first tooth (mandibular central incisor) was 7.1 months. The mean length of the interval between first eruption and completion of the deciduous dentition was 19.3 months, which is shorter than reported earlier. The most frequent order of eruption in both the maxilla and the mandible was central incisor, lateral incisor, first deciduous molar, second deciduous molar. Arch dimensions, spacing, and occlusion were studied from 2.5 to 5.5 years. The mean dimensions changed very little during this period. Changes between first and last casts of individual children were frequently encountered, however. Spacing was more pronounced in the maxilla than in the mandible. In 49 percent of the children, however, the maxillary anterior spacing decreased during the investigation. Changes between upper and lower intercanine segments of individual children were not associated with each other. In the maxilla, changes in intercanine dimension were associated with changes in anterior arch depth at the 1 percent level of significance but not with changes in intercanine width, whereas in the mandible changes were significant for both parameters. Primate spaces were present bilaterally more frequently and were wider than were spaces on the other side of the canines. The frequency of distal canine relationships decreased with age, and the frequency of normal canine relationships increased, but no similar trend was noted in molar relationships. Overjet decreased with age. Open-bite was relatively frequent in the ages from 2.5 to 3.4 but had disappeared completely by 4.5 years. Except for autonomous adjustment of the open-bite, no trends existed in overbite changes. All children gave up their finger-sucking habits before or during this period, and it is suggested that closure of the open-bite and reduction of overjet are due to the cessation of this habit. (Also published in Proceedings of the Finnish Dental Society, Vol. 78, Suppl. IV.) T. M. Graber
176 Reviewsand abstracts 2. The mandible demonstrated significant forward and upward displacement, associated with rotation. 3. The condylar cartilage gained in thickness with increased growth of the condyle on the ninetieth day but returned to normal by day 180. The reaction was considered to have a certain saturation point, rather than being linear. 4. Morphologic changes in the condyle were seen with resorption on the anterior border of the condylar neck and deposition on the posterior border. 5. The mandibular angle was opened by pronounced bone deposition on the posterior ramal border and bone resorption on the inferior mandibular border. 6. The coronoid process demonstrated a backward and upward morphologic change, with resorption on the anterior border and marked deposition on the posterior border. 7. The postglenoid tubercle showed mesial drift and morphologic changes with deposition on the anterior border and resorption on the posterior border. 8. Changes were observed in growth direction of the maxilla. 9. Forward traction on the mandible influenced not only the maxilla but the zygomatic, temporal, and sphenoid bones. T. M. Graber
Thesis abstracts Development
of the Deciduous
Dentition
Marjatta NystrC)m University
of Helsinki,
1982
This academic dissertation is roughly equivalent to a doctoral dissertation in the United States, albeit the work can be done and parts can be published in periodical literature before the final compilation and defense. Five publications serve as the basis of this work. The aim of the investigation was to study formation of maxillary deciduous incisors and canines and mandibular deciduous molars from the age of 6 months onward. In addition, clinical eruption of deciduous teeth and dimensions of dental arches, spacing, and occlusion during the complete deciduous dentition were studied. The longitudinal investigation was started in 1967. Of the 382 first-born children who started the project, 214 were still part of the study at the 5-year examination. Fifty-three siblings joined the project, making a
total of 267. By 1981, the sample size was 185, with subjects ranging in age from 7 to 13 years. Clinical, radiographic, and cast data were compiled and subjected to biometric evaluation. The investigation of tooth formation was cross sectional; the balance of the study was longitudinal. The results are summarized as follows: All deciduous teeth studied showed completion of crowns by the age of 1 year. At 3 years all teeth studied, except the mandibular second molar, had complete root development. No sexual dimorphism was noted. The tooth-emergence study was based on data compiled by the mothers. The mean age at eruption of the first tooth (mandibular central incisor) was 7.1 months. The mean length of the interval between first eruption and completion of the deciduous dentition was 19.3 months, which is shorter than reported earlier. The most frequent order of eruption in both the maxilla and the mandible was central incisor, lateral incisor, first deciduous molar, second deciduous molar. Arch dimensions, spacing, and occlusion were studied from 2.5 to 5.5 years. The mean dimensions changed very little during this period. Changes between first and last casts of individual children were frequently encountered, however. Spacing was more pronounced in the maxilla than in the mandible. In 49 percent of the children, however, the maxillary anterior spacing decreased during the investigation. Changes between upper and lower intercanine segments of individual children were not associated with each other. In the maxilla, changes in intercanine dimension were associated with changes in anterior arch depth at the 1 percent level of significance but not with changes in intercanine width, whereas in the mandible changes were significant for both parameters. Primate spaces were present bilaterally more frequently and were wider than were spaces on the other side of the canines. The frequency of distal canine relationships decreased with age, and the frequency of normal canine relationships increased, but no similar trend was noted in molar relationships. Overjet decreased with age. Open-bite was relatively frequent in the ages from 2.5 to 3.4 but had disappeared completely by 4.5 years. Except for autonomous adjustment of the open-bite, no trends existed in overbite changes. All children gave up their finger-sucking habits before or during this period, and it is suggested that closure of the open-bite and reduction of overjet are due to the cessation of this habit. (Also published in Proceedings of the Finnish Dental Society, Vol. 78, Suppl. IV.) T. M. Graber