Biomedical subjects
Publications and source records attributed to F Popovich.
In normal and Class I malocclusions, ramus and mandibular angles are found to correlate most strongly with cranial base dimensions rather than angles, whereas in Class II malocclusions these angles tend to relate more closely to the cranial base angles.
This paper describes study No. 6 in a series dealing with mandibular growth direction (Lundström and Woodside, 1980). Study No. 5. (Lundström, Woodside and Popovich 1987) investigated facial harmony and disharmony of the facial profile. The present paper describes a study of the frontal views of the same children as paper No. 5. A mixed panel of 17 individuals (four categories of three, four and six people in each) made an aesthetic evaluation of the frontal facial view of 64 subjects (32 of each sex) from the Burlington serial experimental group. The sample consisted of equal numbers of individuals who displayed vertical, average or horizontal mandibular growth between the ages 6-20 years. We calculated correlations between the four assessor groups and found these to be acceptable. On average the panel found no change in frontal appearance between 12 and 18 years because of the balance between individuals improving and deteriorating. Our earlier work showed systematic differences in profile view between those with vertical growth on the one hand and average o horizontal on the other. The vertical cases were more disharmonious than the other categories. Corresponding findings were made also in the frontal view. Mean overall evaluations by all assessors showed a positive correlation between profile and front view assessments.
1. In comparing characteristics associated with the presence or absence of diastema at the age of 16 years, generalized spacing was the only significant factor. 2. In the 230 children who had a diastema of 0.5 mm. or greater at age 9, there was a significant association between the diastema and the amounts of crowding or spacing at age 16. 3. A clinician must analyze the individual case in order to determine whether the diastema is to close through normal development or if there exists a likelihood of its persistence.
The frequency of two non-metric skeletal traits, atlas bridging and clinoid bridging, were examined serially in a randomly chosen sample of 147 families who participated in the Burlington Growth Study. The sample is representative of an Ontario white Anglo-Saxon population. Partial and complete atlas briging occurred in 29.2% of the sample, partial and complete clinoid bridging in 15.2%. Atlas bridging appears at an average age of 10.7 years, clinoid bridging at seven years, demonstrating that these characters are not simply expressions of soft tissue sclerosis in old age. Both traits show no strong associations with bone robusticity although atlas bridging is slightly more frequent in males. Both traits are more frequent in relatives of affected individuals than in the sample as a whole. Correlations between parents and offspring and between sibs are highly significant for atlas bridging, less so far clinoid bridging. These traits should fit either a single gene or quasi-continuous, polygenic model of inheritance. Several tests for polygenic inheritance such as the correlation between first and second born sibs' trait condition, the relationship between trait expression in offspring and total trait incidence in affected parents, and the correlation between trait frequency and expressivity on an intergroup basis were all positive for atlas bridging. The evidence for polygenic inheritance of clinoid bridging is weaker but suggestive. The results obtained in this study for atlas bridging are comparable to data from one earlier family study. The evidence suggests that these two traits should prove useful as genetic markers in skeletal population studies although there is still need for careful control over trait observation and description. Future research should attempt to measure non-metric traits continuously when their underlying distributions are known to be graded.
Body growth at adolescence was later in children of the serial experimental sample of the Burlington Growth Centre who had agenesis of third molars of 4-cusped mandibular permanent first molars. These groups of children tended to have later maximum increment of growth, later completion of the growth spurt, less adolescent prepeak gain and greater postpeak gain in height and weight than the children with four third molars and 5-cusped first molars. Growth of the boys differed significantly (P less than 0.05) according to absence or presence of third molars, whereas in girls it differed significantly (P less than 0.05) by the number of cusps of the mandibular first molars. In skeletal age, the children with the molar reductions were slightly advanced before adolescence, fell behind during prepeak adolescent growth, and caught up to the other children by the end of their growth spurt. Later maturation in association with dental reduction may be an evolutionary trend in man.
Correlations of size of teeth, chin, bone and body were investigated in 118 males and 102 females of the Burlington Growth Centre. In the males, the mesiodistal widths of the mandibular lateral incisors and canines were independently related to the thickness of the cortex of the second metacarpal and to body weight. Bone cortex thickness was significantly related to metacarpal width in males and to body weight in females. Chin depth of the males was significantly related to bone width and to body height, negatively related to tooth width when bone width or body weight was held constant in partial correlations. Bone width and length were significantly related to body height in both sexes.
Although first permanent molar hypoconulid absence, third molar agenesis, and small tooth size are all part of evolutionary trend of dental retardation, each bears a different relationship to dental caries. Caries prevalence in the maxillary and mandibular permanent first molars of the Burlington Research Centre serial experimental group at age 16 years was less in the children whose first molars were missing the hypoconulid. Conversely, caries prevalence in mandibular first molars was greater in the children who had agenesis of third molars. The extraction of first molars due to caries was more frequent in children with agenesis of third molars, less frequent in those with absence of hypoconulids of the first molars and unrelated to tooth size. Caries prevalence was less in small teeth, and occurred least in the small mandibular first molars with four cusps. Whereas this is in harmony with the hypothesis that evolutionary dental reductions resulted from the pressure of caries, the increased prevalence of caries and extractions coinciding with third molar agenesis does not support this view. In addition, agenesis of hypoconulids and agenesis of third molars were related to changes in structures unrelated to caries.
1. Age-, sex-, and growth-type-specific craniofacial templates represent a practical approach to orthodontic case analyses and craniofacial growth. 2. The Burlington Growth Centre Cephalometric Analysis is a practical adjunct to treatment planning. 3. This cephalometric analysis, which combines many analyses, is an assessment of the relative proportions of the face in length, width, and height (static analysis) and an estimation of the future changes (dynamic analysis). 4. As an aid in diagnosis, the template and/or analysis in conjunction with a cephalogram, with provide information pertaining to (q) cranial base length angle, (b) upper and lower face height and maxillary and mandibular height, (c) size and proportions of the facial bones, both anteroposteriorly and in width, (d) denture relationship, both anteroposteriorly and in width, and (e) expected general growth changes.
From the analysis of histories, dental casts, and cephalograms of 471 children of the Burlington Growth Centre sample, interrelationships between the degree of spacing, crowding, diastema and frenum and suture type were derived and the following conclusions were drawn: 1. Suture type remains more constant through development than frenum type. 2. Frenum type is reasonably constant but may change from low to medium or high attachments, but only to a higher level of attachment. 3. Frenum and suture type are related; frenum types 5 and 6 (low attachment) are associated with spacing and with suture types 3 and 4. 4. The primary factors contributing to maxillary diastema appear to be degree of spacing or crowding in most cases, the specific types of sutures and frenum making a minor contribution.
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The chronological age, skeletal age, and morphological age at the time of mineralization of 14 stages of the permanent teeth of 121 boys and 111 girls of the serial experimental sample of the Burlington Growth Centre were contrasted according to whether or not the children had 4- or 5-cusped mandibular permanent first molars, and whether or not they had agenesis of one or more third molars. In the boys with 4-cusped mandibular first molars, the mineralization of the teeth occurred at significantly earlier chronological and skeletal ages when they were significantly shorter in stature. Tooth mineralization was not consistently earlier in the girls with 4-cusped molars, but these girls tended to be taller and heavier than those with 5-cusped molars. In contrast, in both sexes with agenesis of third molars, the mineralization of the teeth was significantly delayed according to chronological, skeletal and morphological evaluation. The change in timing of mineralization was greatest for the second premolars and second molars, and least for the first molars.
The ages at which the maxillary and mandibular teeth of 121 boys and 111 girls reached 14 mineralization stages were determined from serial cephalograms at the Burlington Growth Centre. The present data are more comprehensive than any previously available and can be applied to chronological age determinations in juveniles of indefinite age, and of specimens in anthropological and forensic investigations. The sexes differed in the age at which they attained the stages of mineralization, with the canines demonstrating the greatest difference. In each sex, the ages at identical stages were similar for the corresponding teeth in the maxilla and mandible. Variability in age was greater among the males, especially for the first premolars, and increased with age, except for the third molars. Variability in age of third molar mineralization was greater in females and diminished among both sexes at late stages of root formation.
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In the evolution of primates there has been a tendency towards reduction in jaw length and prognathism, mandibular canine size and first molar cusp number, and third molar presence. These oral structures were contrasted, and compared with cranial size, body height and weight, and finger length in 118 males and 102 females of the Burlington Growth Centre. Body weight was significantly related to canine width and to jaw length and prognathism. These relationships were stronger in the males than in the females. The evolutionary reduction in these dental dimensions may result from an evolutionary reduction in genetically determined body size. In the males the number of molar cusps was related to finger length and cranial height. Agenesis of third molars was related to the length of the maxilla in both sexes. In the females, canine width was related to the number of cusps of the first molars, agenesis of third molars, and length of a finger. Simultaneous reductions in dental structures were more frequent in the females.
This study determined for 121 boys and 111 girls of the serial experimental group of the Burlington Growth Centre the age, time interval and age sequence of 14 stages of mineralization of all tooth types. The two sexes differed significantly in the age at which the stages of tooth mineralization appeared, and in the length of the interstage intervals. In the canines, there was maximum sex difference in mineralization, which was almost 20 per cent and resulted from a delay in the boys. Changes in sequence of mineralization were due to delay rather than to acceleration. Sex differences in tooth mineralization manifested themselves before puberty, and mineralization was not accelerated at puberty. In contrast, post-pubertal mineralization of third molars appeared to be accelerated in both sexes and occurred earlier in the boys.
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The correlations of dental mineralization stages, skeletal mineralization, body-height and weight were determined for each year between age 4 and 14 for 121 boys and 111 girls of the serial experimental group of the Burlington Growth Centre. Dental development related more strongly to morphological development than to skeletal development in both sexes, and skeletal age was more strongly related to morphological age than to dental stage. The relationship of individual teeth to skeletal age, height and weight were different but consistent in a sex-specific pattern. In males, both skeletal mineralization and dental mineralization, particularly of the first molars, were more closely related to height than to weight. In the females, skeletal and dental mineralization, especially of the second molars, were more closely related to weight from age 7 than to height. These relationships were significant in both pre-adolescent and adolescent years. In both these periods, skeletal age and body size related most strongly to late stages of tooth formation. Hence, from an early age, the stages of dental, skeletal and morphological maturation were significantly interrelated in a pattern that was specific for individual teeth and for sex.