[A cephalometric study on the similarity of craniofacial morphology between children and their parents].

This study was performed to estimate genetic influences on craniofacial form and to obtain a method of analysing the characteristics in a child as well as the individual growth prediction in each child. Posteroanterior and lateral cephalographs were used to estimate the morphological similarities of craniofacial form between 150 children and their parents. Subjects consisted of 38 boys and 112 girls who were estimated to mature according to the bone maturity index (B.M.I.) on the hand radiographs and who were older than 13 years chosen from among 3,500 orthodontic patients registered at the University Hospital associated with the Faculty of Dentistry, Kyushu University. The correlation analysis in family, estimation of the sexual linkage, the multi-regression analysis and estimation of the heritability of craniofacial characters were computed. The differences in correlations were also tested between prepuberty and postpuberty craniofacial forms in another 100 children with orthodontic treatment. The results are as follows: 1. The craniofacial form of children was highly correlated with that of their parents. 2. The genetic effects of determining the craniofacial form of offspring by the father were equivalent to those by the mother, but daughters were more affected by parents than were sons. 3. The proportions of multi-regression functions ranged from 3.7 to 34.0 percent. These values are too low to predict the growth of a child. 4. The calculated heritabilities on craniofacial form were from 0.286 to 0.962, with the majority being more than 0.600. 5. The coefficients of correlation between the children and their parents increased with growth, regardless of their orthodontic treatment.

A jointed fan-type expander: a newly designed expansion appliance for the upper dental arch of patients with cleft lip and/or palate.

Most patients with repaired cleft lip and/or palate have malocclusion and show various forms of occlusal discrepancy between the upper and lower dentition. In unilateral clefts, the teeth in the collapsed small segment are usually in lingual crossbite, although in most cases they are in normal buccolingual occlusal relation in the molar region. Expansion appliances should fulfill the following functions: the application of expansion force to the alveolar bone of the maxillary complex without buccal tipping of the teeth (to obtain the differential segmental movement); force to the lateral segments of the maxilla without their distortion; and expansion of the smaller segment without creating posterior crossbite. Unfortunately, many appliances do not satisfy these functions. A new fan-type expansion appliance has been designed by the authors to solve these problems. This appliance consists of three parts, as follow: an expansion screw; four bands (anchorage); and a joint connecting both buccal segments. The expansion screw is set in a direction tangent to the curve drawn by the intended fan-type movement of the collapsed small segment. The joint converts the expansion force from parallel to an arched direction.

Maxillary lateral incisor of subjects with cleft lip and/or palate: Part 1.

As a pilot study, dental casts of 30 patients with unilateral cleft lip and palate were selected and examined from the longitudinal data in the Department of Orthodontics, Kyushu University Dental Hospital. Dental casts of the anterior teeth were sectioned at right angles to the long axis of the tooth 2 to 3 mm below the incisal edge. The teeth were differentiated according to their cross sections. They were classed as lateral incisors or other types by the ratio of labiolingual diameter to mesiodistal diameter and the flatness labiolingually. Dental casts of 309 additional patients with cleft alveolus were examined subjectively based on above findings. In primary dentition, 183 of 184 teeth on the cleft side were incisal type. One tooth was canine type. In permanent dentition, 42 of 78 teeth on the cleft side were conical type, 20 teeth were intermediate type, and 16 teeth were incisal type. As a conclusion, the tooth on the cleft side is almost certain to be a lateral incisor, not a supernumerary canine tooth. As well, their form was normal in the majority of the primary dentition, but malformed in the permanent one.

Parental data used to predict growth of craniofacial form.

The sample for this study consisted of 250 families. From 850 lateral and posteroanterior cephalograms, 81 variables from the X, Y coordinates of 67 landmarks were calculated and matched with the normal distribution. Principal component analysis was used to summarize these 81 variables in proper factor scores. The craniofacial patterns of 500 adults were classified by cluster analysis on the basis of those factor scores. This study introduced the concept of "similar parent" and "dissimilar parent" instead of the father and mother equally. Finally, the following model for predicting the individual growth of craniofacial characters was obtained. The predicted value Y(t) [formula: see text] is the logistic curve used in growth studies, C1X(s) is for the similar parent of a child, and C2X(d) is for the dissimilar parent. Multiple regression functions were calculated for both sexes in each of four craniofacial patterns. The errors of prediction at the average age of 18 years from the data at the average age of 11.6 years were 1.12, 2.88, 2.87, 3.14, and 1.93 mm for the respective distances S-N, N-Me, S-Me, Gn-Cd, and G-G'. These errors in our growth prediction are much smaller than in ordinary normal facial diagrams and may be considered negligible for orthodontic clinical application.

Prediction of coronal size of third molars by factor and multiple regression analyses.

Factor analysis and multiple regression analysis were made to establish a method for the prediction of the unerupted third molar size. The samples were dental casts of 138 adults (69 women and 69 men) who had all their teeth from the central incisor to the third molar, at least in one side of each maxillary and mandibular dentition. Mesiodistal and buccolingual tooth crown sizes were measured with sliding calipers. Five factors were selected from the factor analysis on the tooth crown sizes. Multiple regression analysis with the third molar as the dependent variable was carried out. Independent variables were selected on the basis of the factors obtained from the factor analysis. Two kinds of multiple regression equations were obtained (the first molar was used as an independent variable in one equation and the second molar was used in the other). The accuracy of the prediction was highest when the lateral incisor, the second premolar, and the second molar were used as independent variables in the maxillary dentition, and the central incisor, the first premolar, and the second molar in the mandibular dentition. The mean of the absolute values of the differences between the predicted values and the actual values was 0.5 mm in the maxillary third molar, and 0.42 mm in the mandibular third molar.

Periodontal changes after experimentally induced intrusion of the upper incisors in Macaca fuscata monkeys.

We are studying the biologic aspects of vertical movement of teeth, which are often used in orthodontic treatment involving variations in alveolar tissue. In the present study, the four upper incisors of five infant Macaca fuscata monkeys were intruded vertically from 1.1 to 5.5 mm. The following effects were examined: (1) movement of the gingiva, (2) change in the depth of the gingival sulcus, and (3) microscopic effects on the alveolar tissue. The results were as follows. (1) The gingiva moved in the same direction that the teeth were intruded, but only about 60% as far. (2) The clinical crown shortened and the gingival sulcus deepened. The shortening of the crown and the deepening of the sulcus were both approximately 40% as much as the tooth intrusion. (3) There was no inflammation or swelling microscopically in the gingiva of either the experimental animals or the controls. (4) The epithelium was always attached in the cementoenamel junction, even when the tooth was intruded. As the tooth intrusion was increased, the dentoperiosteal fiber (DPF) and the dentogingival fiber (DGF) terminating in the cementum gradually parted from it; when the tooth was intruded more than 5.0 mm, few fibers terminated in the cementum. It was concluded that the gingival sulcus deepened with horizontal tooth intrusion because of an accumulation of gingival tissue applied with good oral hygiene--not because of swelling around the gingival margin or apical movement of the gingival pocket--and the DPF and the DGF were parted from the cementum gradually as the tooth intrusion increased.

Maxillary lateral incisors of subjects with cleft lip and/or palate: Part 2.

Maxillary lateral incisors on the alveolar cleft were investigated in 431 cleft children registered in the Department of Orthodontics, Kyushu University Dental Hospital. The majority of primary maxillary lateral incisors were located on the distal side of the alveolar cleft in both unilateral cleft lip and alveolus (UCLA) and unilateral cleft lip and palate (UCLP) subjects. Permanent teeth in UCLA tend to be located distally, but in UCLP they tend to be congenitally absent (p less than .01). The majority of primary teeth had normal shapes; the majority of permanent teeth were of intermediate type or were missing congenitally. One third of the UCLA and one half of the UCLP subjects who had primary maxillary lateral incisors were not followed by permanent replacements. The location of the majority of permanent maxillary lateral incisors tallied with that of the primary ones except in four UCLA, ten UCLP, and two bilateral cleft lip and palate (BCLP) subjects. Four UCLA and ten UCLP subjects who had primary lateral incisors on the distal side were followed by their permanent successors on the mesial side. Three UCLP and one BCLP subjects had permanent maxillary lateral incisors even though they had no temporary predecessors.

Familial similarity in dental arch form and tooth position.

This study was done to quantify and compare similarities in dental arch form and tooth position among individuals of various degrees of biological kinship. The sample consisted of 360 dental casts selected from 102 Japanese families, each including both parents and one of their offspring. Most of the subjects had well-aligned permanent dentitions. Coefficients of dissimilarity were obtained by orienting two standard-sized dental arch diagrams plotted from occlusal photographs to the position of best fit. Dissimilarity between adults and children from different families was computed and served as the control data. With few exceptions, the mean dissimilarity between parents and offspring was smaller than that of the nonfamilial pairings; however, statistical differences were not always significant. Among all the teeth observed, the position of both upper and lower central incisors was found to exhibit the least familial similarity. Analysis of variance among pairings of different sources of variation suggested the existence of significant additive genetic effect, both autosomal and sex-linked. Relative contribution of the additive genetic effect in the total variability of this sample was estimated for dental arch form and tooth position to be in the range of 55-60% and 39-77%, respectively. Autosomal additive genetic effects appear to strongly account for the variation in position of the second premolar and of the first molar.

Heritability of dental arch dimensions in humans.

The purposes of this study were to estimate the heritabilities of several human dental arch dimensions and compare the hereditary differences among kinships and among variables. The sample consisted of 102 Japanese families, each including both parents and one of their offspring, and on average all subjects had relatively well-aligned permanent dentitions. The heritabilities of all variables were estimated from the regression of offspring on parent and on midparent. Results showed that genetics played a role regarding dental arch dimensions, and arch perimeter (sum of tooth width) was a more definite genetic-related factor than other arch dimensions, such as width, length, or size. There were few significant hereditary differences between sons and daughters, and between upper and lower arches for each variable. Sex chromosomal involvement was not confirmed, but maternal effects were found to be more evident in daughters than in sons, for both arches. Comparisons among the heritabilities of overall and of anterior arch dimensions indicated that size of the anterior part of the dental arch might be less resistant to environmental factors, especially in case of the lower arch.

Hereditary factors in the craniofacial morphology of Angle's Class II and Class III malocclusions.

We attempted to assess the role of heredity in the development of Angle's Class II and Class III malocclusions by comparing craniofacial morphologic differences between parents with Class II offspring and those with Class III offspring and by analyzing the parent-offspring correlations within each Class II and Class III malocclusion group. Lateral and frontal roentgenographic cephalograms were obtained for ninety-six patients with Class II malocclusion, 104 patients with Class III malocclusion, and their respective parents. Mean cephalometric profile diagrams were superimposed between the two groups of parents as well as between their offspring. Within the two groups, the parent-offspring correlation coefficients were computed for nineteen variables connecting cephalometric landmarks. The differences in the craniofacial complex were evident in the two groups of parents as well as in their offspring. High correlation coefficient values were seen between parents and their offspring in the Class II and Class III groups. Thus, there appears to be a strong familial tendency in the development of Class II and Class III malocclusions. We conclude that the hereditary pattern must be taken into consideration in the diagnosis and treatment of patients with these classes of malocclusion.

Radiologic exposure conditions and resultant skin doses in application of xeroradiography to the orthodontic diagnosis.

Xeroradiography is the recording of radiologic images by a photoelectric process rather than the photochemical one used in conventional radiography. In order to investigate the advantages and disadvantages of xeroradiography in the orthodontic field, minimum xeroradiologic exposure conditions for skull projections, Schüller's and oblique temporomandibular joint projections, and hand projections were established by thirteen examiners and the relationship between the image production and x-ray radiation was discussed in comparison with related findings obtained with conventional film techniques. The advantages of xeroradiograph were finer and clear images caused by the "edge effect" and wide latitude of xeroradiography; the main hazard was the unavoidable larger skin dose required by the projection procedures. The skin doses with xeroradiography were 2.4 to 16.2 times larger than those with conventional film techniques.

Long-term occlusal guidance of a severely intoxicated patient with yusho (PCB poisoning): a case report.

The peculiar dentoorofacial characteristics and 12 years of interdisciplinary management of a patient who was severely intoxicated with the man-made chemical polychlorinated biphenyls (PCBs) are described in this case report. Cephalometric measurements showed that the SNA and SNB angles were reduced but that the developments in height and skeletal maturity were in normal ranges. Gingival hyperpigmentation that was caused by high blood PCB concentration was extremely slow to fade. A cystic mass, diffused trabeculae, and irregular calcification, which were shown on the radiograph and which were caused by high blood levels of PCB, changed gradually. However, the patient had periodontal disease because of horizontal alveolar bone resorption and a deep periodontal pocket, despite good plaque control. After the PCB poisoning the tooth roots were hypoplastic and dilacerated. One root was extracted because of chronic periodontitis. Some teeth were impacted, malposed, or ankylosed.

Management and subsequent 13-year progress of a mandibular fracture with malocclusion in a child--case report.

Under acute conditions, maxillofacial injuries may be treated without the opportunity for an assessment of occlusal irregularities, even when there are mandibular fractures, because life-threatening injuries have priority over occlusion. Consequently, mandibular fractures may result in post-trauma malocclusion and facial deformity. The case history reported is of a male patient who had been involved in a traffic accident in childhood and suffered mandibular fractures. The initial incomplete management resulted in persistent deformation of the mandible, disturbance of dental occlusion and difficulty in mastication. These irregularities were corrected during childhood by non-operative orthodontic treatment. When the patient reached adulthood, some permanent teeth were malformed because the fractures had damaged some tooth germs. However, the permanent dentition in general was almost normal as a result of the corrected primary dentition. Although the alveolar deformity due to the injury remained, the mandibular base was satisfactorily remodelled. The case reported supports the view that early restoration of normal dental occlusion before the eruption of permanent teeth contributes to the establishment of good functional dental occlusion of the permanent teeth.

Relationship between tongue volume and lower dental arch sizes.

The interrelation between the tongue volume and the lower dental arch sizes (arch width and area) was studied by the original methods that we developed. A plane perpendicular to the occlusal plane and 40 mm posterior to the lower incisal point was taken as the posterior border of the tongue and the arch. The tongue volume and the lower dental arch sizes were measured anterior to this border with plaster models. The correlations between the parameters obtained from 74 Japanese adults (37 men and 37 women) with normal occlusion were statistically analyzed. The results showed that (1) both the mean tongue volume and the mean lower dental arch sizes were significantly larger in men than in women; (2) the tongue volume and the lower dental arch sizes were significantly correlated; and (3) these correlations tended to be higher at the more posterior part of the dental arch.

Evaluation of cationic liposome suitable for gene transfer into pregnant animals.

Cationic liposome-mediated in vivo gene transfer represents a promising approach for somatic gene therapy. To assess the most suitable liposome for gene delivery into a wide range of organs and fetuses in mice, we have explored several types of cationic liposomes conjugated with plasmid DNA carrying the beta-galactosidase gene through intravenous injection into pregnant animals. Transduction efficiency was assessed by Southern blot analysis and expression of the transferred gene was evaluated by enzymatic demonstration of beta-galactosidase activity. Through the analysis of several types of recently synthesized cationic liposome/lipid formulations, DMRIE-C reagent, a liposome formulation of the cationic lipid DMRIE (1, 2-dimyristyloxypropyl-3-dimethyl-hydroxy ethyl ammonium bromide) and cholesterol in membrane-filtered water met our requirements. When the plasmid DNA/DMRIE-C complexes were administered intravenously into pregnant mice at day 11.5 post coitus (p.c.), transferred genes were observed in several organs in dams and were expressed. Furthermore, although the copy numbers transferred into embryos were low, we observed reporter gene expression in the progeny.