Palate vault morphology in Down syndrome

Moire topography was used to quantitatively determine the shape of the palatal vault in 57 Spanish patients with Down syndrome (DS) (38 males and 19 females; age range 18-36 years) and in 100 normal controls (N) (76 males and 24 females; age range 20-29 years). The topographic image for each palatal vault was analyzed and approximately 40 sets of coordinates (x, y, z) were recorded. Other parameters, including length, width and maximum height, were recorded from the palate vault images. No appreciable sexual dimorphism in palate dimensions was observed in DS subjects versus the situation in N subjects. Globally, the average N dimensions were significantly greater than those in the DS patients (P < 0.005). A special palatal morphology was found to be associated with DS, with different ratios for the three dimensions (mean factor 0.88 for length, 0.81 for width and 0.73 for height), versus the healthy palatal vaults. It is concluded that palatal morphology in DS fits an elliptic paraboloid. On the other hand, no lineal correlation was observed between height, width and length in the DS and N groups. The scatter plots of bivariate data exhibited a shapeless morphology. The lineal correlation coefficients ranged from 0.008 to 0.33 for the DS and N groups.     

Human palatal growth evaluated on medieval crania using nerve canal openings as references

The purpose of this investigation was to measure postnatal lengthening and widening of the hard palate by use of nerve canal openings as references. The relationship of the dentition to the greater palatine foramina was also investigated. Thirty-nine medieval dry skulls were examined, 22 from children and 17 from adults. All crania were photographed at a 1:1 scale. The dimensions of the maxilla and the location of the dentition were determined from the photographs. The study showed that palatal growth in length in the sagittal plane takes place anterior to the greater palatine foramen. The growth increment in the area between the incisive foramen and the transverse palatine suture is more pronounced than the growth increment in the area between the transverse palatine suture and the greater palatine foramen. The distance from the greater palatine foramina to the posterior margin of the palate did not increase significantly with age. The growth in width seems to continue into adult life. The first permanent molars and the surrounding bone are moved forwards in relation to the greater palatine foramina during growth. The space for the developing maxillary premolars and molars therefore has to be obtained by growth in the transverse palatine suture. © 1996 Wiley-Liss, Inc.     

Palatal thickening and facial form in Paranthropus: Examination of alternative developmental models

Paranthropus is distinctive among hominoids in its possession of a greatly thickened hard palate. Although traditionally considered a structural adaptation to counter high-magnitude masticatory stress, alternative developmental models are equally viable. Three models of palatal thickening were evaluated in this study. A mechanical model interprets palatal thickening as a compensatory response to increased instability of the midpalatal suture effected by an anterior placement of the masseteric muscle mass. This model predicts that palatal thickness is correlated with the length of the palate posterior to the masseteric tubercle. Two non-mechanical models consider the thickness of the hard palate to be structurally related to and therefore correlated with either 1) the degree to which the premaxilla overlaps the hard palate in the subnasal region or 2) the height of the posterior facial skeleton. The correlation of craniofacial variables was assessed intraspecifically in ontogenetic series of great ape and human crania. Tests of correlation were performed for each comparison using both residuals calculated from reduced major axis regression of the variable of interest against a measure of cranial size and shape ratios. A significant correlation of palatal thickness with posterior facial height in Pan suggests that the unusually thick hard palate of Paranthropus is directly related to the increased posterior facial height characteristic of this taxon. Further evaluation suggests that extreme palatal thickening in these specimens occurred by virtue of their possession of a nasal septum morphology in which the vomer extends onto the superior nasal surface of the premaxilla. Such a morphology would have constrained the palatal nasal lamina to maintain the approximate level of the premaxillary nasal lamina throughout the growth process thereby promoting palatal thickening. Am J Phys Anthropol 103:375–392, 1997. © 1997 Wiley-Liss, Inc.     

Selection of appropriate artificial frontal teeth size using dimensions of hard palate

Eighty dentate students participated as a study group and another 74 as a control group. The aim was to determine a possibility to reconstruct maxillary frontal teeth dimensions by use of certain hard palate dimensions. The height (IH) and the incisal (IW), contact point (CtW) and cervical width (CW) of maxillary central incisors (MCI), hamular width (HW) and the distance between the incisive papilla and the palatine foveas (IP-FP) were measured on the maxillary casts. CtW of maxillary lateral incisors and canines were measured too. In the study group the ratios were computed: HW/IW (5.71), HW/CtW (5.69), HW/CW (5.51) and IP-FP/IH (4.76). These ratios were multiplied by incisor's dimensions (obtained from the control group) to calculate the hard palate dimensions. No significant differences were obtained between the calculated and the measured (study group) hard palate dimensions. Furthermore, there was no significant difference between the HW and the Sum of contact-point widths of all maxillary frontal teeth (p > 0.05) in the both groups. The results revealed: 1. MCI width and height might be calculated by dividing dimensions of a patient's hard palate and appropriate ratio; 2. hamular width dimension can be used as a selection guide for the sum of contact-point widths of six maxillary frontal teeth.     

Thickness of masticatory mucosa in the human hard palate and tuberosity dependent on gender and body mass index

The aim of this study was to clinically determine the thickness of masticatory mucosa in the hard palate and tuberosity as potential donor sites for subepitelial grafts for ridge augmentation procedures of small and moderate alveolar ridge defects to improve aesthetics of a pontic area of fixed partial dentures. In 102 periodontally healthy fully dentate subjects the thickness of mucosa was assessed by bone sounding with a periodontal probe. Twenty measurement points were defined, 18 on hard palate located on 3 lines running at different distances parallel to gingival margin and 2 on tuberosity. Data were analysed to determine differences between gender and different body mass index using t-test. The mucosa on the hard palate was significantly thicker than on the tuberosity. The thickest mucosa was registered on the second and the third line behind canines and on all 3 lines behind the first premolar. These areas are recommended as potential donor sites. Males had significantly thicker mucosa than females (p < 0.01), except for the sites behind the first molar (p > 0.05) where the mucosa was the thinnest in the both gender, which was attributed to the protuberance of the palatal root of the first molar. The same was with the body mass index. Therefore canine-premolar palatal region is recommended for harvesting free subepitelial grafts for moderate augmentation of alveolar ridges for achieving optimal aesthetics of the pontic area.     

Sagittal fractures of the maxilla and palate

Sagittal fractures of the maxilla and palate are infrequent and can demonstrate significant instability with conventional methods of treatment. They require that rigid, horizontal stability of the dentition be obtained, as well as restoration of midface projection and height. The most effective and precise management has utilized a combination of open reduction and internal fixation at the piriform aperture and zygomatic buttress and posterior palate, use of a maxillary arch bar as a tension band, and utilization of a palatal splint.     

Palatal and dental arch morphology in Down syndrome

The analysis of palatal vault morphology and maxillary dental arch shape was carried out in the sample of 42 Down syndrome (DS) patients with trisomy 21. The data were compared to those of healthy controls from the same population matched for age and sex. Palatal morphology and upper dental arch shape were studied on hard plaster casts of the patients and controls. No sexual dimorphism in palatal and dental arch shape was observed in DS and controls. Normal palatal shape was more frequent in controls than in DS subjects (52.38% vs. 28.57%; p < 0.05). DS patients displayed significantly higher frequency of shelf-like or "stair palate" (38.1%) than controls (11.9%) (p < 0.02). The younger age group (3-14 year) showed much higher frequency of "stair palate" than controls (26.19% vs. 2.38%; c2 = 9.72; p = 0.003). The older group of DS patients did not show increased frequency of such shape of the palatal vault. There was no significant difference in dental arch shape between DS patients and controls. High frequency of shelf-like palate in DS subjects is decreasing by age. The obtained results indicate that palatal vault morphology is subjected to the age related changes. These changes can be attributed to the growth of caraniofacial structures and increased tonus of tongue and other orofacial muscles.     

Early palatal changes in complete and incomplete cleft lip and/or palate.

Early palatal development in various complete and incomplete forms of cleft lip and/or palate (CLP) was studied from birth to 3 months of age by means of dental casts. Palatal morphology (shape) and dimensions--based on reproducible reference points--were determined in a group of 128 CLP children and 68 normal children who served as controls. Substantial normal palatal growth during the first 3 months of life was observed. Round arch forms changed into oval arch forms. Growth mainly takes place in the sagittal direction (+4 mm) (transverse: +1 mm). Palates of CLP children differed significantly dependent on the type of cleft and whether the cleft was complete or incomplete. Cleft lip and alveolus children and bilateral cleft lip and palate children had more elongated palatal arches, whereas unilateral cleft lip and palate children and cleft palate children had wider palatal arches than the control group. Incomplete clefts differed from the control group in the same direction as their complete cleft forms, though less distinctly. Preoperative orthopedics used in CLP patients does not stimulate growth. On the contrary, it even restricts growth.     

第二恒磨牙正锁[牙合]畸形相关因素的研究

目的探讨引发下颌第二磨牙正锁(牙合)的相关因素,为口腔正畸临床诊断和治疗提供参考。方法随机抽取800例符合条件的病例作为研究对象。男349例,女451例,平均年龄21.7±3.31岁,其中45例发生第二磨牙正锁(牙合)。测量上颌后段牙弓间隙,下颌后段牙弓间隙,ANB角,上颌第一磨牙区和上颌第二磨牙区的牙槽弓宽度和下颌第一磨牙区和下颌第二磨牙区的牙槽弓宽度,对测量值进行统计分析。结果第二磨牙正锁(牙合)的发生率为5.6%,其性别构成差异无显著性(P>0.05)。回归方程:第二磨牙正锁(牙合)=22.9748 2.0257×上颌后段牙弓拥挤度 1.5372×下颌后段牙弓拥挤度 1.0071×ANB角度 0.3785×上颌第二磨牙处牙槽弓宽度-0.4897×下颌第二磨牙处牙槽弓宽度。结论第二磨牙正(牙合)与上颌后段牙弓拥挤有显著的相关关系,与下颌后段牙弓拥挤度、ANB角度和上颌第二磨牙处牙槽弓宽度呈正相关关系,与下颌第二磨牙处的牙槽弓宽度呈负相关关系。     

A prospective evaluation of the prevalence of submucous cleft palate in patients with isolated cleft lip versus controls.

Although there is an established relationship between cleft lip and overt cleft palate, the relationship between isolated cleft lip and submucous cleft palate has not been investigated. To test the hypothesis that patients with isolated cleft lip have a greater association with submucous cleft palate, a double-armed prospective trial was designed. A study group of 25 consecutive children presenting with an isolated cleft lip, with or without extension through the alveolus but not involving the secondary palate, was compared with a control group of 25 children with no known facial clefts. Eligible patients were examined for the presence of physical criteria associated with classic submucous cleft palate, namely, (1) bifid uvula, (2) absence of the posterior nasal spine, and (3) zona pellucida. Nasoendoscopy was subsequently performed just after induction of general anesthesia, and the findings were correlated with digital palpation of the palatal muscles. Patients who did not satisfy all three physical criteria and in whom nasoendoscopy was distinctly abnormal relative to the control group were classified as having occult submucous cleft palate. Classic submucous cleft palate was found in three study group patients (12 percent), all of whom had flattening or a midline depression of the posterior palate and musculus uvulae on nasoendoscopy and palpable diastasis of the palatal muscles under general anesthesia. An additional six study group patients (24 percent) had similar nasoendoscopic criteria and palpable diastasis of the palatal muscles; they were classified as having occult submucous cleft palate. No submucous cleft palate was identified in the control group. Seventeen patients in the study group had an alveolar cleft with a 53 percent (9 of 17) prevalence of submucous cleft palate. In the present study, classic submucous cleft palate in association with isolated cleft lip was 150 to 600 times the reported prevalence in the general population. All children with an isolated cleft lip should undergo peroral examination and speech/resonance assessment no later than the age of 3 years. Any child with an isolated cleft lip with velopharyngeal inadequacy or before an adenoidectomy should be assessed by flexible nasal endoscopy to avoid missing an occult submucous cleft palate.     

Ontogeny of craniofacial sexual dimorphism in the orangutan (Pongo pygmaeus). I: face and palate

The orangutan is widely recognized as a highly dimorphic species. An ontogenetic approach to the study of sexual dimorphism can assist researchers in understanding both where and when these differences develop. In this study, 357 orangutans from Borneo were divided into five developmental stages representing infancy to mature adulthood. Three-dimensional (3D) coordinate data from 16 landmarks representing the face and palate were analyzed by means of a Euclidean distance matrix analysis (EDMA), a quantitative method for the comparison of forms. Three separate analyses (an age-specific static comparison of forms, a sex-specific analysis of growth trajectories, and an intersex comparison of patterns of relative growth) were carried out with the intent to describe the rate, timing, magnitude, and pattern of growth in the orangutan face and palate. The results indicate that generally males and females share a similar, but not identical, pattern of growth or local form change, but differ in growth rate, timing, and magnitude of difference. Dimorphism in the face and palate can be localized in infancy and traced throughout all age intervals. Orangutan females grow slightly faster than males from infancy to adolescence, at which time male growth exceeds female growth. Female growth ceases with the advent of adulthood, while male growth continues (i.e., both the number and magnitude of the dimorphic dimensions increase). Males and females are similar in facial dimensions and growth related to the orbits, upper face, and palate width. They maintain these similarities throughout development. However, they differ in facial and nasal height, palate length, snout projection, depth of the nasopharynx, and hafting of the face onto the skull. The face broadens and the zygomatic bone flares dramatically in adult males, corresponding to the development of cheek pads. While growth patterns are similar between the two sexes, they differ in the lateral orbit, snout projection, and hafting of the face onto the cranium. Adult dimorphism is the result of growth patterns experienced throughout life, and it is not equally expressed across the cranium. An understanding of patterns of dimorphism, along with the magnitude of difference, may be helpful for interpreting dimorphism in the fossil record.     

47,XXX females,sex chromosomes,and tooth crown structure

Summary Enamel thickness of the maxillary permanent central incisors and canines in seven Finnish 47,XXX females, their first-degree male and female relatives, and control males and females from the general population were determined from radiographs. The results showed that enamel in the teeth of 47,XXX females was clearly thicker than that of normal controls. On the other hand, the thickness of dentin (distance between mesial and distal dentinoenamel junctions) in 47,XXX females' teeth was about the same as that in normal control females, but clearly reduced as compared with that in control males. It is therefore obvious that in the triple-X chromosome complement the extra X chromosome is active in amelogenesis, whereas it has practically no influence on the growth of dentin. The calculations based on present and previous results in 45,X females and 47,XYY males indicate that the X chromosome increases metric enamel growth somewhat more effectively than the Y chromosome. Possibly, halfway states exist between active and repressed enamel genes on the X chromosome. The Y chromosome seems to promote dental growth in a holistic fashion.     

Inhibitory effect of corticoids on the proliferative pattern in mouse palatal processes.

The formation of the secondary palate in mice is accompanied by intensive mitotic activity, which is mainly concentrated at the medial edges of the palatal processes. In control H-Velaz randombred fetuses the mitotic activity culminated approximately 24 h before palatal-shelf horizontalization, so that the period of intensive cell proliferation coincided with the period when cleft palate could be induced by cortisone administration. Effects of teratogenic doses of corticoids, injected directly into amniotic sac of embryos on day 13 (0.3 mg hydrocortisone) or im to pregnant females on day 12 (7.5 mg cortisone acetate), on the proliferative peak in palatal processes were studied using intraamniotic injection of colchicine. Counts of colchicine-blocked mitoses in histological serial sections revealed both a significant decrease in overall mitotic density and a posterior shift of the proliferative peak in the palatal processes of fetuses treated with doses of corticoids producing cleft palate.     

Racial differences in cephalometric measurements and incidence of cleft lip with or without cleft palate

A study was made to search for the morphological basis and, indirectly, the developmental basis for racial differences in risk of cleft lip with or without cleft palate CL(P) in Hawaii. A total of ten linear and three angular measurements read from anterior-posterior cephalographs were examined on 210 healthy adult Caucasian, Hawaiian, Japanese, Chinese, and Filipino subjects. Racial comparisons were made on these variables after adjusting for age and sex. Generally, the CL(P) high-risk group consisting of Japanese, Chinese, and Filipinos had smaller dimensions than Caucasians and Hawaiians in the variables (S-N, N-Ba) representing size of cranial base and the measurements of face height (N-A, N-ANS), palatal length (ANS-PNS), and mandibular length (Ar-Gn). Facial width relative to palatal length as measured by the ratio of bizygomatic diameter to palatal length showed a marked consistency with the racial differences in CL(P) risk. Possible significance of this finding is discussed in relation to development of the orofacial structure.     

Roentgen cephalometric studies on skull development in rats. II. Normal and hypophysectomized males; sex differences

Growth of the skull in normal male rats of the Long-Evans strain has been studied by serial roentgen cephalometry (under anesthesia) from 27 to 280 days of age, and has been compared with the retardation following hypophysectomy and with growth data obtained on females in an earlier similar study. The dimensions measured represented major skull regions and segments, and in some instances allowed calculation of indices (e.g., neurocranial width/length ratio) which would show changing proportions. In general, the skull showed the more rapid and prolonged growth characteristic of male rats' skeletal development when compared with that of females. Viscerocranial (“facial”) length and width were notable in this respect. On the other hand, growth in neurocranial width and height ceased at a time and size much like that in females. Examination of the possibility that the adult female skull might correspond closely to that of an immature male disclosed that though this might be true for the neurocranium, facial dimensions showed distinctive sex differences. After hypophysectomy at 27 days of age males (as also females) showed marked reduction of growth but not complete cessation. Dimensional increases were between one-fifth and one-fourth of the normal gains. The ratios computed showed that the proportions of infancy were retained after early hypophysectomy.     

Formation of anterior maxillary teeth in 0-3-year-old children with cleft lip and palate and prenatal risk factors for delayed development

Formation of deciduous and permanent maxillary incisors and canines was studied in 361 children with cleft lip and palate. Altogether, 704 occlusal X rays of the children aged from 2 weeks to 41 months were assessed using a 13-stage scale. The early timing of tooth development was in both dentitions close to that reported for healthy children. However, developmental asymmetry was noted between contralateral teeth on the cleft and noncleft sides. In the unilateral cleft lip and palate group, every tenth cleft-side deciduous central incisor, deciduous canine, and permanent central incisor was delayed compared to the corresponding contralateral tooth. The formation timing was also compared within 11 prenatal and hereditary variables. Risk factors for delayed development were low placental weight, short gestation, mother's use of drugs during pregnancy, first in birth order, cleft with multiple additional malformations, and relatives having malformations other than oral clefts. However, the associations between a risk factor and tooth development were weak.     

A comparative study of tooth and dental arch dimensions in Jewish children of different ethnic descent. I. Kurds and Yemenites

Dental casts of 99 Kurdish and 98 Yemenite Jewish children evenly distributed between the sexes, aged 12 years, were measured for mesio-distal and buccolingual tooth dimensions, and arch depth and width. Dental dimensions showed significant differences between the two groups in certain permanent teeth in mesiodistal length, while in the buccolingual diameter the differences did not reach statistical significance. Dental arch form in Kurdish children was more rounded due to significantly bigger arch width, while arch depth was not significantly different from Yemenites. Intragroup sex differences were found in both groups with reference to arch dimensions, while in the dental parameters they were more strongly expressed in Kurdish children.     

Occlusal morphology in 45,X females

Seventy-two 45,X females (Turner syndrome) were examined for occlusal anomalies. Prevalence comparisons were made with first-degree female relatives and female population controls. The method of Bj?rk et al [1964] was used for determination of malocclusion. The results clearly suggest an increased prevalence of occlusal anomalies in 45,X females. The most common malocclusions are cross bite, large maxillary overjet, distal molar occlusion, and a tendency to open bite. These anomalies reflect an imbalanced growth of the craniofacial skeleton in three dimensions. These findings suggest that genes on the human X chromosome are of importance in the harmonious growth and development of the craniofacial skeleton and ultimately normal occlusal morphology and relations.