Yasuhide Takahama

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.

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 Angles 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.

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.

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.

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.

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.

The dimensions of the tongue in relation to its motility.

To obtain basic information about the motility and dimensions of the tongue, the tongue volume was measured and the change in its length and location was noted while the tongue was undergoing protrusion, and then the relationships among those parameters were examined statistically. The tongue was measured at rest from the tip to a point 40 mm posterior corresponding to a plane connecting the lower permanent second molars. The subjects were 100 Japanese men and women. It was found that (1) maximum protrusion of the tongue is accomplished by two functions combined--a forward movement and a longitudinal stretching; the volume of the tongue was significantly correlated with its stretching. (2) The mean length of the tongue in the most protruded position was about 20% longer than its length in the resting position; it was stretched most in the segment from 1 to 2 cm posterior to its tip. (3) The mean tongue volume was 25.3 cm3 in men and 22.6 cm3 in women, a statistically significant sex difference; the volume was about 12% larger in men than in women. (4) There was no correlation between the tongue volume and the length of the most extraorally protruded tongue. The results suggested that the volume of the tongue can be estimated from the stretched length of the tongue in the most protruded position, if it is measured properly.