Hellman's Dental Age Research Articles

Biomechanical evaluation of maxillary protraction with an orthodontic anchor screw: a three-dimensional finite element analysis

ABSTRACT Purpose The purpose of this study was to biomechanically evaluate maxillary protraction using an orthodontic anchor screw. We conducted three-dimensional finite element analysis to determine the initial displacement and stress distribution during maxillary protraction by comparing a conventional method involving fixation on teeth with maxillary protraction using an orthodontic anchor screw. Materials and methods We used X-ray computed tomography data obtained from Hellman Dental Age IIIA dry human skulls to create a skeletal anchorage model and a dental anchorage model as finite element models. In each model, a load of 6 N was applied in the anteroinferior direction at 0°, 10°, 20°, 30°, and 40° to the occlusal plane by means of a traction hook and the initial displacement and stress distribution were analysed. Results For the anterior nasal spine (ANS) sagittal displacement was greater in the skeletal anchorage model than in the dental anchorage model. In the central incisors and first molars, greater sagittal displacement was observed in the dental anchorage model compared with the skeletal anchorage model. In both models, vertical displacement was 20°, indicating maximum suppression of rotation in the maxilla. The zygomaticomaxillary and zygomaticofrontal sutures demonstrated high stress at 0° and 10° in the dental anchorage model, and at 20°, 30°, and 40° in the skeletal anchorage model. Conclusions These results indicate that tooth and bone–borne maxillary protraction using an orthodontic anchor screw inserted in the palatal region may be of value for the early mixed dentition period in patients with maxillary deficiency.

Quantitative proteomic analysis of gingival crevicular fluids from deciduous and permanent teeth.

Gingivitis commonly progresses to periodontitis in permanent dentition but rarely in deciduous teeth. Little is known about the biochemical differences between gingiva of deciduous and permanent teeth. Here, we compared the protein profiles of gingival crevicular fluids (GCF) from the gingiva of deciduous and permanent teeth. Forty children with mixed dentition (Hellman's dental age IIIA) were selected and GCF samples were collected from deciduous cuspids and central incisors in the maxilla. Pairs of GCF samples were labelled using isobaric tags to permit quantitative comparison of protein abundance in the samples using liquid chromatography-electron spray ionization-tandem mass spectrometry. Sixty-two proteins were upregulated in deciduous teeth GCF and 54 in permanent teeth GCF. In particular, neutrophil-derived proteins, including myeloperoxidase and lactoferrin, were repeatedly higher in deciduous teeth GCF than in permanent teeth GCF. These differences were verified using ELISA (p<0.01). In contrast, immunoglobulin components were upregulated in permanent teeth GCF. Neutrophil-related proteins were enriched in deciduous teeth GCF and immunoglobulins in permanent teeth GCF. This suggests that neutrophil accumulation plays a protective role in innate immunity against bacterial infection in gingival tissue of deciduous teeth.

Design of safe foods that induce mastication in very young children

Background/purposeIn order to obtain information for the design of foods for infants and other young children, we analyzed bite size and mastication of children eating test foods with their fingers. MethodsUsing baked stick biscuits (Food A: newly designed biscuits for children; or Food B: commercially available control biscuits) as the test foods, we analyzed how children grasped the foods themselves with their fingers, bit into the items, and finished swallowing. Among 79 children who went to nursery school or preschool in a specified prefecture and gave consent to the objectives of this study, there were 54 for whom three dimensional motion analysis data from two trials for each food were obtained. ResultsBite weight was significantly larger for Food A, and the bite length was significantly greater for Food B. The number of jaw movements was about 25 for both foods, being the least in the primary occlusion completion period group (Hellman's dental age ⅡA) for Food B. The maximum mastication distance for Food A was significantly longer, by 1.25 times, in the early period of primary occlusion completion group (Hellman's dental age ⅠC) and was longer, by approximately 1.2 times, in the II A period group. The total trajectory distance was significantly longer for Food A, by 1.2 times, in the IC period group and by 1.1 times in the IIA period group. ConclusionIn designing foods for children, it is considered necessary to examine the design by dividing the target ages into 1–2 years and 3–5 years. It is also suggested that Food A not only requires a greater number of jaw Q2 movements but also is likely to produce more dexterous mandibular movements.

Observation of maxillary incisive canal using dry skulls between Hellman's dental age IA and IIIC.

The maxillary incisive canals were observed in childhood from infancy to school-aged children to clarify their development. Cone-beam computed tomography was performed to investigate 44 dry child skulls. Two-dimensional images of various planes in the maxillary incisive canal were reconstructed on a computer using 3-dimensional visualization and measurement software. Then, antero-posterior angulation, and antero-posterior and lateral axes of the maxillary incisive canal were measured at the inferior and middle levels. The mean difference of angulation between the inferior and middle levels was 2.3 degrees in IIC, and 11.1 degrees in IIIC. The mean ratio of the lateral axis to antero-posterior axis at the middle level was 2.54 in IIC, and 1.93 in IIIC. In conclusion, it was antero-posteriorly straight from IA to IIC, and, after IIIA, it curved at the middle level. The cross-sectional shape in IIC was depressed with a larger lateral axis.

Changes of Oral Pathogens in Children with Respiratory Disease

Respiratory disease occurs frequently in children. The nasal cavity, trachea, and oral cavity are considered the primary routes of infection. We aimed to investigate the types of microbial pathogens present in the oral cavities of children with respiratory disease. In addition, we compared the detection rates of different pathogens between the oral cavity and the nasopharynx according to Hellman dental age. We included 32 children who were hospitalized for respiratory disease and classified them according to Hellman dental age. Specimens were collected using 2 palate swabs: one taken at hospital admission and the other at discharge. The culture results of the samples were compared with those of nasopharyngeal cultures. The following 6 bacterial strains were detected in both the palate and nasopharynx: α-Streptococcus, Corynebacterium, Haemophilus influenzae, Haemophilus parainfluenzae, MRSA, and Neisseria. In the comparison of the detection rates, Neisseria were significantly more frequently detected in the palate. MRSA was detected at a significantly higher rate in the nasopharynx. When the detection rates of different bacteria were compared according to Hellman dental age, significant differences were observed in the detection rates of α- Streptococcus in stage IA and Neisseria in stages IC and IIA. We noted that the bacterial load of specific bacteria in the palate increased with Hellman dental age.

Locating Mandibular Foramen in Children with Mandibular Retrognathism in Mixed Dentition.

Background and aims. One of the most common reasons forthe inferior alveolar nerve block anesthesia failure is the variation in mandibular foramen location. The aim of this study was to assess the location of mandibular foramen in children with mandibular retrognathism in comparison to children with normal skeletal occlusion in the mixed dentition.Materials and methods. One hundred and twenty panoramic radiographs of patients in mixed dentition period, undergoing orthodontic treatment, were selected based on inclusion criteria, skeletal occlusion and stage of dental development. The radiographs were divided into two groups: I: 60 panoramic radiographs of patients with normal skeletal occlusion (15 in each of the Hellman dental age stages); II: 60 panoramic radiographs of patients with mandibular retrognathism (15 in each of the Hellman dental age stages). The radiographs were traced and the linear distance from the mandibular foramen to the borders of the mandibular ramus and its angular position were identified. The measurements were compared between the two groups and among the four dental age groups by t-test, ANOVA and post hoc tests.Results. No statistically significant differences werefound between the patients with normal skeletal occlusion and patients with mandibular retrognathism (P>0.05). Statistical tests showed significant differences in the vertical location of mandibular foramen and gonial angle between the four dental age groups (P<0.05).Conclusion. Mandibular retrognathism does not have a significant impact on the location of the mandibular foramen in the mixed dentition period. The child’s dental age would be considered in the localization of the mandibular foramen.

Oral pathogens in children with respiratory disease

Abstract Objective Respiratory disease occurs frequently in children. The nasal cavity, trachea, and oral cavity are considered the primary routes of infection. We aimed to investigate the types of microbial pathogens present in the oral cavities of children with respiratory disease. In addition, we compared the detection rates of different pathogens between the oral cavity and the nasopharynx according to Hellman dental age. Materials and methods We included 32 children who were hospitalized for respiratory disease and classified them according to Hellman dental age. Furthermore, 32 control children were included as controls. Specimens were collected using two palate swabs: one taken at hospital admission and the other at discharge. The culture results of the samples were compared with those of the nasopharyngeal cultures. Results The following six bacterial strains were detected in both the palate and the nasopharynx: α-Streptococcus , Corynebacterium , Haemophilus influenzae , Haemophilus parainfluenzae , methicillin-resistant Staphylococcus aureus (MRSA), and Neisseria . In the comparison of the detection rates, Neisseria were significantly more frequently detected in the palate. MRSA was detected at a significantly higher rate in the nasopharynx. When the detection rates of different bacteria were compared according to Hellman dental age, significant differences were observed in the detection rates of α-Streptococcus in stage IA and Neisseria in stages IC and IIA. Discussion We noted that the bacterial load of specific bacteria in the palate increased with Hellman dental age. Furthermore, the increase in bacterial load in the oral cavity at stage IA, when teeth have not yet erupted, suggests the need for oral management.

하악 과성장형 골격성 III급 부정교합 아동의 치아성숙도에 관한 연구

현재까지의 많은 연구들을 통해 치아의 발육상태와 골격성 부정교합과의 연관성이 보고되어 왔다. 본 연구는 방사선학적 방법을 통하여 정상교합군과 하악 과성장형 골격성 3급 부정교합군의 상하악 치령 및 제2대구치 맹출률을 비교, 분석하여, 파노라마 방사선 사진으로 평가 가능한 상하악 치아성숙도의 차이가 하악 과성장형 골격성 3급 부정교합의 감별진단 요소로 의의가 있는지 알아볼 목적으로 시행되었다. 부산대학교 소아치과에 내원한 Hellman 치령 IIIA의 환자를 대상으로 정상교합군과 하악 과성장형 골격성 3급 부정교합군 각 50명을 선택한 후, 이들의 파노라마 방사선 사진을 이용하여 Demirjian법으로 각 군의 상하악 치령 및 제2대구치 맹출률을 구하고 그 차이를 비교, 분석하였다. 그 결과 정상교합군과 하악 과성장형 골격성 3급 부정교합군의 상하 치령의 차이는 각각 0.66세와 1.20세로 하악 과성장형 골격성 3급 부정교합군에서 유의하게 더 큰 차이를 보였으며(p < 0.05), 상하 제2대구치 맹출률은 두 그룹 간 유의한 차이를 보이지 않았다(p > 0.05). In growing children it is frequently found that dental maturation is strongly influenced by the growth rate of maxilla or mandible. If there is evidence to prove this, it might be utilized as a criterion in the early diagnosis of skeletal malocclusion, even before the object's real skeletal features are yet revealed. The purpose of this study was to find out if the difference of dental maturation in over-grown mandible in children with skeletal Class III has any relationship with some skeletal features of mandible. 50 patients in Hellman dental age IIIA with normal occlusion and Class III malocclusion of mandibular over-growth type respectively were selected as study objects. The age estimation was performed on maxillary and mandibular teeth, eruption rate of the 2nd molars of each group have been measured on panoramic radiography, and the differences in dental age of the upper and lower jaw were analyzed under Demirijian's method. The results were as follows: The difference of dental age of maxillary and mandibular teeth between the two groups was 0.66 and 1.20 years respectively, with a higher difference in the experimental group (p < 0.05). The difference of eruption rate of the maxillary and mandibular second molar was not found between two group (p >0.05).

Hellmanの歯齢II CからIV Aにおける叢生と咀嚼筋筋電図との関係

Hellmanの歯齢II CからIV Aにおける叢生と咀嚼筋筋電図との関係

상악 열성장형 전치부 반대교합 아동에 있어서의 상악 치아 성숙도

초기 혼합치열기 어린이의 전치부 반대교합 평가과정에서는 부정교합의 골격적 특성이 강할수록 상악 치아의 맹출 및 형성이 현격히 지연되는 것이 흔히 감지되었다. 만일 두개안면부의 전후방적 골격적 특성이 치아의 성숙도와 연관성을 가진다면, 치아의 발육과 맹출에 대한 평가가 반대교합의 조기 감별진단의 한 도구로써 가치가 있을 것으로 판단되었다. 본 연구는 초기 혼합치열기의 상악 열성장형 반대교합 아동에 있어서 상악의 치아 석회화도와 맹출률, 그리고 측두방사선규격사진 분석을 통한 수종의 계측치 간 연관성을 규명할 목적으로 시도되었다. 부산대학교치과병원 소아치과에 교정적 목적으로 내원한 Hellman 치령IIA IIC 아동 중, 전치부 반대교합을 보이는 III급 부정교합 증례로부터 상악 열성장군과 상악 정상군 각 50례를 무작위 추출하여 연구 대상으로 하였다. 이들의 측두방사선 규격사진과 파노라마방사선사진을 이용하여 각 군의 골격적 양상, 상하악 치아의 석회화도와 맹출률을 구하고 그 차이와 상관성을 분석하여 다음과 같은 결과를 얻었다. 1. 양 군의 상악 치아 성숙도 비교에 있어서 상악 열성장군의 제 1대구치만 석회화도와 맹출률 이 낮게 나타났다(p<0.05). 2. 역령은 상악 치아의 석회화도와 맹출률과 높은 상관관계를 보였다(p<0.05). 3. 상하악의 전후방적 악골 관계중 Wits는 상악 제 1대구치의 석회화도와 맹출률 모두를, SNA는 맹출률을 예측할 수 있는 유용한 지표로 나타났다(p<0.05). In the process of assessing the children with anterior crossbite in early mixed dentition, it has frequently been detected that the stronger the skeletal pattern of the malocclusion is, the more markedly delayed the development and eruption of maxillary teeth are. If the anteroposterior characteristics of craniofacial skeleton has any relationship with dental maturation, the evaluation of dental development and eruption was thought to be able to contribute to early diagnosis of crossbite in children. This study was performed for the purpose of elucidating the relationship between dental maturation of maxillary teeth and some cephalometric values in children with anterior crossbite of maxillary undergrowth type in early mixed dentition. Among the children in Hellman dental age IIA and IIC who attended the Pediatric Dental Clinic of Pusan National University Hospital with orthodontic problems, cases with Class III malocclusion were classified and 50 cases of maxillary undergrowth type and type with normal maxilla respectively were randomly selected and studied as subjects. From their lateral cephalographs and panoramic radiographs, their anteroposterior skeletal features, the dental maturity and eruption rate were obtained of each group and data were analyzed to yield the results as follows: 1. Comparing the maturity of maxillary teeth of both groups, only the first molars of maxillary undergrowth group showed significantly slower development and eruption (p<0.05). 2. There was high correlation between maturation of maxillary 1st molar and chronological age(p<0.05). 3. Among the parameters of anteroposterior relationship of skeletal pattern in maxilla and mandible. Wits was revealed as a useful index to predict both the calcification and eruption rate of the 1st molars whereas SNA was to eruption rate(p<0.05).

機能的矯正装置を用いた成長期ｈｅｍｉｆａｃｉａｌ ｍｉｃｒｏｓｏｍｉａ症例の１治療例

Hemifacial microsomia (HFM) is characterized by unilateral underdevelopment of facial bones and soft tissues originating from the first and second branchial arches. In this article, we report an adolescent HFM patient treated with a functional appliance to facilitate mandibular growth.The patient was a 7-year 1-month-old boy with the chief complaint of open bite and facial asymmetry. He had Pruzansky Grade II deformity of the mandible. The overjet was 7.0 mm, the overbite was -5.0 mm, and Hellman's dental age was IIC. The left lower second premolar was congenitally missing and the left lower first molar showed a 90-degree mesio-buccal rotation. The postero-anterior cephalometric analysis revealed that the mandible was shifted to the left side and the occlusal plane was tilted upward on the left side. The lateral cephalometric analysis showed a small and distally-located mandible with clockwise rotation. Prior to orthognathic treatment started at 15 years old, the first phase of treatment was initiated with a functional appliance and headgear for a period of 1 year and 10 months at 12 years 10 months old.During the initial 4 years of treatment from the first consultation at 7 years 1 month old, the amount of occlusal plane inclination and lateral shift of the mandible increased due to a lack of patient cooperation. Nevertheless, use of the functional appliance improved the facial asymmetry due to lateral shift of the mandible. On the lateral cephalogram, a remarkable mandibular growth was found on the asymptomatic left side of the mandible.

Observation of maxillary sinus septa and bony bridges using dry skulls between Hellman's dental age of IA and IIIC

Maxillary sinus septa and bony bridges were observed using dry skulls in childhood, classified based on Hellman's dental age, to clarify maxillary sinus septum formation. Eighty-eight maxillary sinuses of 44 dry skulls and a cone-beam computed tomography (CBCT) unit were used. The locations of the septum, defined as a pointed bony structure originating from the inferior wall, and bony bridge, defined as a bony structure between the maxillary sinus wall and dental germ, were antero-posteriorly recorded, and the superoinferior distance, distance from the bony palate, and angle to the median palatine suture were measured. The rate of septum presence in the maxillary sinus was high (41.7%) in IIIC, and the septa were located in the deciduous molars, premolars, and molars. Also, all bony bridges were related to the median maxillary sinus wall, and the rate of the maxillary sinus showing a bony bridge was high in IIA and IIIA. Septum presence in the maxillary sinus was observed in IIA, IIC, IIIA, IIIB, and IIIC of Hellman's dental age. Also, bony bridges were observed in IC, IIA, IIC, IIIA, IIIB, and IIIC of Hellman's dental age.

Assessment of oropharynx using cone beam computed tomography—Change in volume during oropharynx growth—

Recently airway blockage accidents have increased in Japan, and airway blockage accidents involving children account for 12% of the total. However, the causes of airway blockage accidents are not clear. The oropharynx plays an important role in feeding and swallowing by helping to prevent aspiration and airway blockage accidents. Few studies, however, detail the changes in volume of the oropharynx during growth. The relationship, therefore, between the volume of the oropharynx and growth was investigated in this study. The subjects, 50 males and 50 females aged 7 to 15 years, were grouped according to a dental development age index (Hellman Dental Age), resulting in a dental development range from IIC to IVA. Cone beam computed tomography (CB Mercuray, Hitachi) was used to scan each subject's head, and a three-dimensional modeling system was used to measure the oropharynx volume, height and other. The mean and standard deviation of the height of males was 35.48 ± 6.85 mm and of females, 34.78 ± 7.42 mm. In male and female subjects, the height of the oropharynx airway increased from IIC to IVA. The mean and standard deviation of the oropharynx volume of males was 5,570.79 ± 3,790.30 mm 3 and of females, 4,942.80 ± 2,818.75 mm 3 . In male and female subjects, the volume of the oropharynx airway increased significantly from IIIC to IVA. Therefore, this study suggests that there is a strong relationship between the increase of the oropharynx airway and the time and condition of eruption of the second molar teeth from period of IIC to IVA of the Hellman Dental Age index.

The relationship between body balance and occlusal balance of Japanese children during the deciduous dentition period

The relationship between children's deciduous dentition occlusal balance and body's gravity center movement was studied. The participants of this study were 128 children with Hellman's Dental Age IIA stage at a nursery school. The distance and the area of gravity center movement (GCM) when the participants had their eyes-opened and eyes-closed were measured with automatic posture analytical devices. Occlusal abilities including occlusal contact area, average pressure, maximum occlusal pressure, occlusal force and occlusal balance were measured with the Dental Prescale® system. Analysis of occlusal balance was determined by separating the middle group (|x|≤5mm) from the deflection group (|x|>5 mm) based on the position of occlusal balance center. A significant difference was found between the occlusal balance of the middle group (n=96) and the occlusal balance of the deflection group (n=32) in the distance and area of gravity center movement with eyes-opened and closed. The distance and area of gravity center movement of the middle group was less than that of the deflection group. Analysis of body balance was determined by the good balance group and bad balance group based on the GCM area with eyes-closed. A difference was found between the good balance group and the bad balance group in the occlusal contact area and occlusal force. The occlusal contact area and occlusal force of good balance group were higher than the bad balance group. Body and occlusal balance was observed to have some interactive influence during Hellman's Dental Age IIA period. The influence of occlusal balance on body balance is much stronger and obvious than the influence of body balance over occlusal balance. Occlusal balance can influence on the body balance most of the time while body balance can sometimes influence on the occlusal balance.

The relationship between body balance function and occlusal function during the mixed dentition period

The aim of this study was to investigate the relation between body balance and occlusal balance during the mixed dentition stage. Fifty-six healthy children with Hellman's Dental Age IIIA: (31 boys and 25 girls) with an average age of 8.1 years, were selected from an elementary school. The body balance, distance and area of gravity center movement (GCM) were measured with automatic posture analytical devices. Occlusal abilities were measured with pressure-sensitive sheets (Dental Prescale ® ), including occlusal contacts area, average occlusal pressure, maximum occlusal pressure, occlusal force and occlusal balance. Analysis of occlusal balance was determined by separating the middle group (| x | ≤ 5 mm) from the deflection group (| x | > 5 mm) based on the position of occlusal balance center. Similarly, the children were instructed to perform the GCM area of eyes-closed exercise. The first 25% of the participants with the best balance were grouped as the good balance group; and the last 25% with the worse balance were grouped as the bad balance group. Results showed that occlusal contact area and occlusal force of the middle group were more than the deflection group, GCM distance and area of the middle group were less than the deflection group. occlusal contacts area and occlusal force of the good balance group were more than the bad group. Body balance function and occlusal balance function were observed to have mutual influence during Hellman's Dental Age IIIA stage in this study.

Morphological Study on Quadruplets by Cephalometric and Model Analyses

Clarifying the genetic factors involved in maxillofacial growth and development is very important in orthodontic treatment planning and prognosis. However, few dental studies have examined multiple births. The present orthodontic evaluation was conducted using orthodontic data from a set of quadruplets. Orthodontic evaluation was performed on a set of quadruplets (1 girl and 3 boys) aged 9 years and 7 months at the initial visit. Although all 4 children weighed only about 1,400 g each at birth, height and body weight subsequently normalized. Mean skeletal age of the quadruplets was 10 years and 2 months, about 6 months ahead of their calendar age. In all 4 children, facial profile was mostly symmetrical and convex. Intraoral findings showed a Hellman's dental age of IIIA, together with spacing of the upper anterior teeth. Both overbite and overjet were 5-7 mm, and mesial step of the terminal plane was noted. Model analysis showed that tooth materials were on the large side, while arch width was narrow. Cephalometric analysis revealed that the ANB of the first- and fourth-born children was 6 degrees , and skeletal maxillary protrusion due to mandibular retrusion was diagnosed. The second- and thirdborn children exhibited no marked skeletal abnormalities.

Dento-alveolar development in unilateral cleft lip, alveolus and palate

Background and objective: Palatal surgery for cleft lip, alveolus and palate is considered to have the most powerful negative impact on maxillary growth. The aim of this study was to compare dento-alveolar development of the permanent dentition and morphology of the palate after surgery in unilateral cleft lip, alveolus and palate patients following two types of palatoplasty: supraperiosteal flap vs mucoperiosteal flap technique. Patients: Thirty-eight patients born between 1976 and 1983 with a complete unilateral cleft of lip, alveolus and palate were studied. Fifteen patients were treated with supraperiosteal flaps (SP group), and the other 23 patients with mucoperiosteal flaps (MP group). In this cross-sectional study, dental casts of stage IV A of Hellman's dental age in each patient were used. Methods: The following distances were measured: (1) transverse distance C–C′, (2) transverse distance M–M′, (3) palatal length, (4) palatal height. Results: No statistically differences were seen between the SP and MP groups regarding C–C′ and M–M′. However, palatal length and palatal height were significantly greater in the SP than in the MP group. Conclusion: The technique that leaves no denuded palatal bone is considered to be advantageous for the development of the alveolar process.

乳歯歯根嚢胞の４例における臨床的検討

Radicular cysts arising from deciduous teeth are rare, although they are the most common cysts of the jaws. During the 20-year period between 1976 and 1995, we studied four cases (three boys, one girl) of radicular cysts arising from deciduous teeth at our hospital. These cases were diagnosed clinically and histologically. The patients' ages ranged from 9 years to 12 years, with a mean age of 11 years 4 months, and they were all in Hellman's Dental Age III B. Three patients had gingival swelling as a primary symptom, and the other had no symptoms. All lesions were located in the second premolar area of the mandible. Three cases were unilateral, and one was bilateral. All lesions showed swelling on the buccal side of the mandibular bone in the areas of the cysts. In all the lesions, X-ray examination showed cyst-like radiolucency at the apex of the second deciduous molars. Extirpation or mar supialization of the cysts was the treatment of choice for all lesions. There has been no recurrence, and all permanent teeth erupted at their normal positions in all patients.

Palate Morphology in Children with Cleft Palate with Palatalized Articulation

This study was designed to examine postoperatively morphological characteristics of the palate of children with cleft palate with palatalized articulation. Palate morphology was measured in children with good velopharyngeal closure function after surgery, who were classified in Hellman's Dental Age II A group with unilateral cleft lip and palate, and the groups of children with palatalized articulation (CP-P) and normal articulation (CP-N) were compared. The results showed that the group of children with palatalized articulation was characterized by small palatal volume. In particular, there was narrowing and shortening of the anterior palate, and the palate was shallow. It was surmised that morphology may be one cause of palatalized articulation. Accordingly, it is important that early tongue-clicking movements are encouraged in patients exhibiting narrow palate morphology.

頭部固定条件が45度Oblique Cephalogramの映像に与える影響に関する研究

When the cephalograms are taken, the child's head is, as a rule, immobilized on the Cephalostat with his Frankfort horizontal plane being parallel to the floor. But it sometimes happens that the exposure is made while the head tilts somewhat upward or downward around the transmeatal axis. So it is necessary to study the influence of the head positioning on the image of the cephalogram in order to evaluate the growth changes with series of 45-degree oblique cephalograms.The horizontal and vertical measurements were made mainly on the mandible of two dried skulls of Hellman's dental age IIA and IIIB. The measurements of the space posterior to the dental arch by three reference planes for measurements were also compared. The results were as follows:1) In the horizontal measurements, the influence of the head position on the image of the 45-degree oblique cephalogram was negligible and the enlargement and distortion can be regarded as uniform.2) In the vertical measurements, the influence of the head position was obvious and some kind of correction or relative evaluation will be needed.3) In the measurements of the space posterior to the dental arch by the three reference planes, the influence of the head position was negligible.