Postnatal structure of the sella turcica in Down syndrome

Sella turcica and facial bones: Morphological integration in the human fetal cranium

OBJECTIVES

The cranial base plays a significant role in facial growth, and closer analyses of the morphological relationship between these two regions are needed to understand the morphogenesis of the face. Here, we aimed to study morphological integration between the sella turcica (ST) and facial bones during the fetal period using geometric morphometrics.

MATERIALS AND METHODS

Magnetic resonance images of 47 human fetuses in the Kyoto Collection, with crown-rump lengths of 29.8-225 mm, were included in this study. Anatomical homologous landmarks and semilandmarks were registered on the facial bones and the midsagittal contour of the ST, respectively. The shape variations in the craniofacial skeleton and the ST were statistically investigated by reducing dimensionality using principal component analysis (PCA). Subsequently, the morphological integration between the facial bones and ST was investigated using two-block partial least squares (2B-PLS) analysis.

RESULTS

PCA showed that small specimens represented the concave facial profile, including the mandibular protrusion and maxillary retrusion. The 2B-PLS showed a strong integration (RV coefficient = 0.523, r = .79, p < .01) between the facial bones and ST. The curvature of the anterior wall of the ST was highly associated with immature facial morphology characterized by a concave profile.

CONCLUSION

The strong integration between the two regions suggested that the anterior ST may be associated with facial morphology. This result quantitatively confirms previous studies reporting ST deformities in facial anomalies and induces further research using postnatal subjects.

Sella turcica morphometrics in subjects with down syndrome

OBJECTIVE

Since the number of patients diagnosed with Down syndrome seeking orthodontic treatment is increasing, clinicians could contribute by applying diagnostic modalities used frequently in the orthodontic field for research purposes. Thus, The aim of the present study is to implement morphometric methods to investigate the size and shape of sella turcica in subjects with Down syndrome.

MATERIALS AND METHODS

In this retrospective study, archive records of 24 individuals with Down syndrome were compared to 48 healthy controls matched for age and gender. Parameters such as sella anterior, midpoint, and posterior height were measured, as well as sella width, area, and length were calculated. Independent sample t-tests were applied for the comparison of differences in sella turcica dimensions. Geometric morphometric analysis of the sella was performed with, implementing methods such as Procrustes superimposition and principal component analysis. Statistical significance was set at p<0.05.

RESULTS

Statistically significant differences were found for sella anterior height, sella midpoint height, sella posterior height, sella maximum height, sella length, and sella area. All the aforementioned values were significantly increased in the Down syndrome subjects (p<0.05). Principal component analysis (PCA) depicted a statistically significant difference in sella shape between patients with Down syndrome and healthy controls (p<0.05).

CONCLUSIONS

Subjects with Down syndrome presented significantly increased sella turcica dimensions as well statistically significant differences in shape compared to healthy controls.

Anatomical features of sella turcica with comprehensive literature review

OBJECTIVE

This study aimed to explore the relationship between skeletal patterns and the frequency of sella turcica bridging in a sample of young Turkish adults in order to provide a better understanding of the relationship between craniofacial morphology and sella turcica abnormalities.

METHODS

A total of 90 individuals aged between 18 and 25 years were examined in this study. The individuals were classified according to their skeletal pattern, specifically Class I, Class II, and Class III. Each group consisted of 15 males and 15 females. The length, depth, and anteroposterior diameter of sella turcica were calculated. The shape and bridging of sella turcica were estimated using lateral cephalometric images. All data were correlated and statistically analyzed according to skeletal patterns, genders, and age.

RESULTS

The mean length, depth, and anteroposterior diameter of sella turcica were 7.02±2.13, 7.56±1.38, and 10.54±1.3 mm in Classes I-III, respectively. There was no significant difference between the dimensions of sella turcica according to gender and age (p˃0.05). The length of sella turcica was larger in Class III, and the depth of sella turcica was larger in Class II individuals (p<0.05). A total of 44.4% of the individuals had normal sella turcica, while the remaining 56.6% had other types of sella turcica. It was determined that 31.1% of the individuals have no calcification, 62.2% had partial calcification, and 6.7% had total calcification.

CONCLUSION

The normal dimensions, shape, and bridging of the sella turcica can be used by the orthodontist for diagnosis, treatment planning, and evaluation of various pathological conditions associated with the sella turcica.

Investigating the Relationship between the Dimensions and Morphology of Sella Turcica with the Long-Face Growth Pattern and the Vertical Growth Pattern

Introduction

The sella turcica is one of the important landmarks of lateral cephalometry, which is used in orthodontics for the diagnosis, treatment plan, and evaluation of skeletal development and maturity. The purpose of the present study is to investigate the relationship between the dimensions and morphology of sella turcica with the long-face growth pattern and people with an open bite. This study also examines the relationship between sella turcica bridging (STB) and the vertical growth pattern.

Methods

As many as 153 radiographs were analyzed using the Romexis software, considering the basal, gonial, and FMA angles to determine the vertical growth pattern of the face. The basal angle was also used to check for an open bite. Of these patients, 80 had a long vertical face growth pattern, and 73 had a normal face growth pattern. The four landmarks of tuberculum sellae, dorsum sellae, sellae floor, and posterior clinoid were determined on the cephalograms to measure the length, depth, and anteroposterior diameter of the sella turcica.

Results

In this study, it was found that the chance of developing a long face in people with partial and complete bridging is 8.37 and 1.92, respectively. An increase in the length of the sella turcica for one unit decreases the chance of a long face, and as the depth of the sella turcica increases, the chance of a long face increases.

Conclusions

STB is frequently seen in people with long faces. However, this finding should be considered in relation to other diagnostic parameters. The shorter the length and higher the depth of sella turcica, the higher the chance of developing a long face.

Morphology of the Sella Turcica: A Meta-Analysis Based on the Results of 18,364 Patients

BACKGROUND

This meta-analysis aimed to present data on the sella turcica (ST) morphology and variations. Furthermore, a detailed morphometric analysis of the ST was conducted.

METHODS

Major online databases such as PubMed, Scopus, Embase, Web of Science, and the Cochrane Library were searched through. The overall search process was conducted in three stages.

RESULTS

This meta-analysis was based on the results of 18,364 patients and demonstrates the most up-to-date and relevant data regarding the morphology of the ST in the available literature. Four classification methods of the ST shape can be distinguished, in which the most commonly occurring variants are the normal ST (55.56%), the U-shaped ST (73.58%), the circular type of ST (42.29%), and non-bridging ST (55.64%). The overall midpoint height of the ST was 6.59 mm (SE = 0.13). The overall length of the ST was 9.06 mm (SE = 0.15). The overall volume of the ST was 845.80 mm3 (SE = 288.92). Four main classification methods of ST morphology can be distinguished in the available literature. Various morphometric characteristics of the ST may be applied in clinical practice to evaluate its shape, dimensions, and normal or pathological variants.

A CBCT Investigation of the Sella Turcica Dimension and Sella Turcica Bridging in Different Vertical Growth Patterns

This study aimed to compare the sella turcica dimensions and sella turcica bridging (STB) via cone-beam computed tomography in different vertical patterns and then analyze the link between the sella turcica and vertical growth patterns. The CBCT images of 120 skeletal Class I subjects (an equal proportion of females and males; mean age of 21.46 years) were divided into three vertical growth skeletal groups. Student's t tests and Mann-Whitney U tests were used to assess the possible diversity in genders. The link between sella turcica dimensions and different vertical patterns was explored by one-way analysis of variance, as well as Pearson and Spearman correlation tests. The prevalence of STB was compared using the chi-square test. Sella turcica shapes were not linked to gender, but statistical differences were observed among different vertical patterns. In the low-angle group, a larger posterior clinoid distance and smaller posterior clinoid height, tuberculum sellae height, and dorsum sellae height were determined, and the incidence of STB was higher (p < 0.01). Sella turcica shapes were linked to vertical growth patterns, mainly involving the posterior clinoid process and STB, which could be used as an index to assess vertical growth trends.

Relationship between palatally impacted canines and dimensions and morphology of sella turcica: A cone-beam computed tomography study

INTRODUCTION

This study aimed to analyze the association of unilateral and bilateral palatal canine impaction with the dimensions and morphology of sella turcica from 3-dimensional cone-beam computed tomography (CBCT) images.

METHODS

CBCT images of patients with bilateral (BPI) (n = 12; 9 female 3 male; 20.75 ± 5.88 years) and unilateral (UPI) (n = 35; 22 female 13 male; 19.28 ± 5.57 years) palatally impacted canines were compared with a control group (n = 56; 34 female 22 male; 20.82 ± 4.88 years). Linear measurements regarding sella turcica were made, and its morphologic variations were categorized. Two group comparisons were made with the Student t test or Mann-Whitney U-test, whereas one-way analysis of variance or Kruskal-Wallis tests were used for multiple group comparisons. Categorical variables were compared using the chi-square or Fisher exact test as appropriate. The binary logistic regression analyses and correlations using Spearman or Pearson correlation analyses were used to determine associations between variables (P <0.05).

RESULTS

Sella diameter was significantly smaller in the BPI group compared to UPI and control groups. There was a significant association between sella diameter and BPI when compared with the control group (χ2[1] = 9.150; P = 0.008). There were no significant differences between groups in the distribution of sella turcica morphology.

CONCLUSIONS

Despite the similar genetic origin of the sella turcica region and teeth, the association of palatal canine impaction with dimensions and morphology of sella turcica was weak. Both local and genetic factors might contribute to the ectopic position of the canine.

Is there a relationship between transverse maxillary deficiency and sella turcica: A cephalometric analysis study?

Objectives:

The aim of this study was to investigate the dimensions and morphological variations of sella turcica and to test whether a relationship exists between sella turcica and transverse maxillary deficiency.

Materials and Methods:

The cephalometric radiographs of patients older than 17.99 years, which have been taken before the orthodontic treatment, and patient records were analyzed to investigate sella turcica dimensional and morphological analysis. Linear measurements of sella are as follows sella length, sella width, sellar area, sella height anterior, posterior, and median. The sella turcica morphological shape analysis was performed into six groups (normal sella turcica, oblique anterior wall, sella turcica bridge, double contour of floor, irregularities of the posterior part of the dorsum sella, and pyramidal shape of the dorsum sella). The width of the maxillary arch is measured by the digital caliper. Male participants with a maxillary width of less than 30.8 mm and a maxillary width of less than 31.1 mm in female patients in the first molar region were determined as a transverse maxillary deficiency. The mean dimensions of sella turcica and the relationship between cases with transverse maxillary deficiency and non-skeletal anomaly were compared using independent samples t-tests. The transverse maxillary deficiency and the sellar morphology relationship were compared using Chi-square test. Post hoc multiple comparisons and analyzes were performed at 95% confidence interval by Bonferroni correction.

Results:

The sella length measurements yielded higher values among the patients with transverse maxillary deficiency (P < 0.05). The normal sella morphology had quantitative superiority in patients without skeletal anomaly in comparison with transverse maxillary deficiency cases (P < 0.05). It was observed that the sella turcica bridge had a statistically superiority in patients with transverse maxillary deficiency (P < 0.05).

Conclusion:

The increased sellar measurement and sella turcica bridging, may provide knowledge about possible transverse maxillary deficiency.

Sella Turcica Morphology on Cephalometric Radiographs and Dental Abnormalities-Is There Any Association?-Systematic Review

BACKGROUND

The sella turcica is a saddle-like structure in the middle cranial fossa on the intracranial surface of the sphenoid bone, visible on lateral cephalograms routinely conducted for orthodontic diagnosis. The development of facial structures follows similar traits to the sella turcica: glandular anomalies may be associated with functional disorders, e.g., altered hormonal levels, thus influencing dental development. The aim of this study is to find out if there is any association between the morphology of the sella turcica on cephalometric radiographs and the presence of dental abnormalities. (2) Methods: The search was conducted on 27 January 2021 in four search engines: Medline (PubMed Central), Scopus, Web of Science, Embase. The keywords used in the search strategy were as follows: "sella turcica" AND ("dental abnormalities" OR "dental anomalies" OR "malocclusion"). Since all the studies finally included were retrospective case-control studies, the Newcastle-Ottawa Quality Assessment Form for Case-Control Studies was applied. (3) Results: The search strategy identified 465 articles: 289 from PubMed, 121 from Scopus, 32 from Web of Science and 23 from Embase. Finally, 10 full-text papers were included into qualitative analysis. (4) Conclusions: Sella turcica bridging is very frequent among orthodontic patients. A clear association exists between dental abnormalities and sella turcica bridging.

Sella turcica morphology in patients with genetic syndromes: A systematic review

The sella turcica is an important anatomical reference used in orthodontics for the evaluation of craniofacial growth. Studies have found variations in the sella turcica morphology in patients with syndromes affecting the craniofacial complex. This review aims to determine whether genetic syndromes involving the craniofacial complex are associated with abnormal radiographic sella turcica morphology and whether there is a pattern of malformation which is consistent within each syndrome. An electronic database search was conducted to identify relevant studies. We included primary studies describing the morphology of the sella turcica on lateral radiographs in human subjects with genetic syndromes involving the craniofacial complex. No restrictions were placed on language or timeframe. PROSPERO registration CRD42019148060. Thirty-eight studies were included in this review. A 'J'-shaped sella was found in patients with Hutchinson-Gilford-Progeria syndrome and other syndromes. A bulbous dorsum sellae was highly prevalent Cleidocranial dysplasia, and a bulbous dorsum sellae and uneven contours of the clivus was found in Cri du chat syndrome. A steep clivus was described in patients with Axenfeld-Rieger syndrome. An oblique anterior wall was the most frequent malformation found in Down's syndrome. Genetic syndromes affecting the craniofacial complex are associated with abnormal morphology of the radiographic sella turcica. Clinicians should be observant of abnormal sella turcica morphology which can be a sign of undiagnosed or subclinical syndromes. More high-quality studies are needed which use standardized and objective methods of determining the morphology of the sella turcica.

Size and bridging of the sella turcica in Japanese orthodontic patients with tooth agenesis

The purpose of this study was to investigate the association between the size and bridging of the sella turcica and tooth agenesis, and whether the likelihood of second premolar agenesis can be predicted from the sella turcica size and bridging in Japanese orthodontic patients. Patients were divided into four groups of 32: groups 1 and 2 consisted of patients with agenesis of the maxillary and mandibular second premolars, respectively; group 3, patients with severe tooth agenesis; and group 4, patients without tooth agenesis. Each group was divided into two subgroups of 16 each based on the patient's age: patients under 14 years of age (groups 1A through 4A, group A) and patients 14 years of age or older (groups 1B through 4B, group B). Lateral cephalograms were used to evaluate the size and bridging of the sella turcica. The interclinoidal distance (ID) was significantly shorter in groups 1 and 3 than in group 4, and in group 3 than in group 2. Group B exhibited significantly greater depth, diameter, area, and perimeter of the sella turcica than group A. Groups 3 and 1B had a significantly higher prevalence of sella turcica bridging than groups 4 and 4B, respectively. Maxillary second premolar agenesis and severe tooth agenesis were associated with a reduced ID irrespective of age and increased occurrence of sella turcica bridging. The early emergence in life of a short ID might be a predictor of possible second premolar agenesis in later life.

Fetal Anatomy of the Optic Strut and Prechiasmatic Sulcus with a Clinical Perspective

OBJECTIVE

The main objective of the study was to show the morphologic features of optic strut (OS) and prechiasmatic sulcus (PS) in the fetal skull base with a surgical anatomical perspective.

METHODS

Twenty-three fetal cadavers (9 female, 14 male) with an average age of 21.70 ± 3.12 (range: 16-28) weeks of gestation in the inventory of the Anatomy Department were included in the study. Measurements were made with a digital image analysis software and goniometer.

RESULTS

The sulcal length, interoptic distance, planum length, and sulcal angle were detected as follows: 3.91 ± 0.74 mm, 6.88 ± 1.04 mm, 6.55 ± 1.51 mm, and 24.52 ± 9.51°, respectively. Considering the location of the posteromedial margin of OS according to PS, OS was identified as the sulcal in 56.5% (13 cases), postsulcal in 30.4% (7 cases), and asymmetric in 13% (3 cases). According to the sulcal length and angle, PS was identified as type 1 in 26.1% (6 cases), type 2 in 21.7% (5 cases), type 3 in 30.4% (7 cases), and type 4 in 21.7% (5 cases).

CONCLUSIONS

Our findings suggest that the sulcal length and angle reach adult size in utero. Taking into account the fetal and the gathered adult measurements, the high percentage of steep angle compared to flat angle show that after birth, PS become more flat, probably depending on the variations of the sphenoid sinus pneumatization. Thus, more studies conducted on the alterations in PS and OS types relative to the pneumatization are needed in terms of patient positioning, selection of appropriate surgical approach, and intraoperative decision-making.

The morphology and bridging of the sella turcica in adult orthodontic patients

Background

The purpose of this study was to determine and compare the shapes, sizes, and bridging of the sella turcica in patients with different skeletal patterns and genders.

Methods

It was a cross-sectional comparative study. The samples were divided into three groups according to the skeletal pattern viz. Class I, Class II and Class III, and each group consisted of 40 samples (20 males and 20 females). The lateral cephalograms were traced and the sella turcica was assessed for its size, shape, and bridging.

Results

The mean length, anteroposterior diameter and depth of sella turcica were 8.13 ± 2.03 mm, 9.60 ± 1.43 mm and 6.40 ± 1.21 mm respectively. The mean length of sella turcica was 7.91 ± 1.52 mm in Class I, 7.32 ± 1.62 mm in Class II and 9.16 ± .2.42 in Class III skeletal pattern; anteroposterior diameter was 9.30 ± 1.02 mm in Class I, 9.15 ± 1.28 mm in Class II and 10.35 ± 1.64 mm in Class III skeletal pattern; and the depth was 6.40 ± 0.92 mm in Class I, 6.07 ± 1.01 mm in Class II and 6.74 ± .1.54 mm in Class III skeletal pattern. There were significant differences in length and anteroposterior diameter and sella turcica between Class I, Class II and Class III skeletal patterns (p = 0.01), (p = 0.01) respectively. There was no significant difference in size of sella turcica between different genders and age groups. Sixty percent of the patients studied had normal Sella morphology. Partial Sella turcica bridging and Sella turcica bridging was seen in this study in 23.33% and 11.67% of patients respectively.

Conclusion

Sixty percent of the patients had normal sella turcica. There were significant differences in lengths and anteroposterior diameters among Class I, Class II and Class III patients. The larger size was present in skeletal Class III patients.

Maxillary and Sella Turcica Morphology in NewbornsWith Cleft Lip and Palate

Objective

The first aim was to examine maxillary developmental fields by analyzing bone size parameters within the maxillary bone complex in newborns with unilateral cleft lip (UCL) and unilateral cleft lip and palate (UCLP). The second aim was to evaluate sella turcica morphology in unilateral cleft lip and unilateral cleft lip and palate.

Subjects and Methods

Axial and profile radiographs from 40 newborns (boy–girl, 1:1) in each group (20 unilateral cleft lip and 20 unilateral cleft lip and palate) were randomly selected among radiographs taken for optimizing treatment planning. Analysis of maxillary bone size was performed on axial radiographs and size parameters were measured. Furthermore, analysis of sella turcica morphology was performed on profile radiographs. The results were divided into groups with normal morphology and severe deviations in the morphology.

Results

The maxillary areas were significantly shorter and broader in unilateral cleft lip and palate than in unilateral cleft lip. A profound asymmetry in the maxillary areas was seen in unilateral cleft lip and palate, but not in unilateral cleft lip. In both cleft types, approximately half of the individuals had deviations in sella turcica morphology. The most severe deviations occurred in newborns with unilateral cleft lip and palate.

Conclusions

In newborns with unilateral cleft lip and palate, the maxillary areas are significantly shorter, broader, and more asymmetric than in newborns with unilateral cleft lip. The present study showed that bone structures are a suitable parameter for characterizing the craniofacial developmental fields. Additionally, a high incidence of deviations in sella turcica morphology might indicate that this area is affected in individuals with clefts.

Association between sella turcica bridging and palatal canine impaction

INTRODUCTION

The association of sella turcica bridging and various dental anomalies has been an area of interest for researchers. Based on the evidence of a common embryologic origin between sella turcica and the teeth, the objectives of this study were to measure the dimensions of sella turcica and to test whether an association exists between sella bridging and impacted canines.

METHODS

Orthodontic records comprising standard-quality lateral cephalograms and dental panoramic radiographs were selected. Thirty-one patients with palatally impacted canines (20 female, 11 male; mean age, 18.4 ± 8.9 years) and 70 controls with erupted canines (35 male, 35 female; mean age, 17.1 ± 7.5 years) were included in the study. Comparison of sella dimensions between the patients and the controls was carried out by independent sample t tests, whereas the association of sella bridging with impacted canines was analyzed using the chi-square test.

RESULTS

The frequencies of complete and partial calcification of sella in the patients were 8 (25.8%) and 17 (54.8%), respectively, whereas those in the controls were 0 and 36 (51.4%), respectively. The frequency of sella bridging was significantly higher in subjects with canine impaction than in the controls (P <0.001). The sagittal interclinoidal distance was found to be significantly reduced in the patients (P = 0.028). According to the statistical analysis, age and sex do not influence the dimensions and calcification of sella turcica.

CONCLUSIONS

Sella bridging is frequently found in patients with impacted canines. Hence, sella bridging can complement other diagnostic parameters in confirming the status of canine impaction.

Dimensions and morphologic variations of sella turcica in type 1 diabetic patients

INTRODUCTION

Some chronic diseases are associated with changes in the morphology of sella turcica, and type 1 diabetes is the most common chronic disease in children and adolescents. Therefore, the aim of this study was to evaluate the size and morphology of sella turcica in patients with type 1 diabetes compared with a healthy control group.

METHODS

The study included 76 type 1 diabetic patients (38 boys, 38 girls; ages, 14.16 ± 2.46 years) and 76 controls (38 boys, 38 girls; ages, 14 ± 2.08 years). The groups were categorized as pubertal and postpubertal according to bone age. The length, height, and diameter of sella turcica were measured. Then the morphology of sella turcica was analyzed and categorized as normal, oblique anterior wall, bridging, double contour of the floor, irregularity in the posterior part of dorsum sellae, or pyramidal shape of the dorsum sellae. All measurements were made on tracings of cephalometric radiographs. Differences between the groups were tested with the Mann-Whitney U test. Categorical data were evaluated with the Fisher exact test, and the Bonferroni correction was made. The significance level was assigned as P <0.05.

RESULTS

There was no statistically significant difference in the dimensions of sella between the diabetic patients (diameter, 12.20 ± 1.49 mm; length, 10.49 ± 1.55 mm; height, 8.07 ± 1.25 mm) and the controls (diameter, 12.45 ± 1.43 mm; length, 10.90 ± 1.73 mm; height, 8.29 ± 1.66 mm). However, diameter and length increased with age in the overall assessment. Length was greater in the postpubertal controls (11.39 ± 1.69 mm) compared with the pubertal controls (10.41 ± 1.64 mm). Diameter was greater in the postpubertal diabetic patients (1.283 ± 1.55 mm) than in the pubertal diabetic patients (11.56 ± 1.12 mm) and was specifically higher in postpubertal boys. Normal sella morphology was less common in general in the diabetic patients, particularly in the diabetic boys and diabetic pubertal boys (P <0.05).

CONCLUSIONS

The measurements concerning sella were similar in the type 1 diabetic and control subjects, but dysmorphologic types were more common in diabetic patients.

Absent sella turcica: a case report and a review of the literature

Absent sella turcica is an extremely rare and dramatic radiographic finding. It may be isolated or occur in the presence of other anomalies, often involving the adenohypophysis. Our evaluation of a female infant with multiple anomalies including absence of the sella turcica, a normal pituitary in the craniopharyngeal canal, normal pituitary function, choanal atresia and anomalies of the appendiceal skeleton prompted a review of the occurrence and biology of an absent sella turcica.

The Morphology of the Sella Turcica in Monozygotic Twins

The purpose was to compare the sella turcica morphology of individuals within pairs of monozygotic twins with normal karyotype and to analyze the similarity between the observed morphology and the morphology of non-twins at the same age with normal karyotype. Profile radiographs from 84 individuals of 42 twin pairs (18 male and 24 female pairs, aged 18–23 years) comprised the material. Sella turcica measurements from non-twins aged 6–21 years were used as normal reference. Length, depth and diameter of the sella turcica were measured and controlled by re-measurements. Pearson's correlation coefficient was used for comparison of individuals within twin pairs. For comparison of twins and non-twins, normal standard values for length, depth and diameter were subtracted from the twin values. For the mean values of these differences, confidence limitspvalues andtvalues were calculated. The study showed that the size of the sella turcica may be partly similar and partly dissimilar within the pair of monozygotic twins. Statistical evaluation of the data showed correlations between length, depth and diameter of the sella turcica between the two twin individuals in the same twin pair. Differences in sizes are observed between individuals in the twin material and individuals in the non-twin material. As a conclusion, the twin males were more similar within the twin pair, but deviated more from the non-twin material than the females. Female twins had more discrepancy within the twin pair, but deviated less from the non-twin material than the males.

Prevalence and patterns of permanent tooth agenesis in Down syndrome and their association with craniofacial morphology

OBJECTIVE

To (1) document the prevalence and patterns of hypodontia (permanent tooth agenesis) in Down syndrome (DS) and (2) explore whether maxillary or mandibular hypodontia or simultaneous agenesis of all third molars was associated with differential alterations of the craniofacial morphology.

MATERIALS AND METHODS

Longitudinal panoramic radiographs of 25 white patients with DS (12 male, 13 female; mean age, 15.1 years) treated at The Hospital for Sick Children, Toronto, Ontario, Canada, were evaluated to document hypodontia. Cephalometric measurements of subjects with maxillary or mandibular hypodontia or agenesis of all third molars were compared with those of subjects without hypodontia in these regions using analysis of covariance adjusted for age, gender, and proportion of other missing teeth in the total number of missing teeth.

RESULTS

Hypodontia was seen in 92% of the sample when third molars were considered and in 56% when third molars were not considered. Hypodontia was more prevalent and severe in females. The most frequently agenetic teeth were maxillary and mandibular third molars > maxillary lateral incisors > mandibular second premolars > mandibular incisors > maxillary second premolars > maxillary second molars. Simultaneous agenesis of all third molars was seen in 52% of the sample. Maxillary hypodontia was not associated with significant regional craniofacial differences, while mandibular hypodontia was associated with decreased mandibular length and increased ramus∶body ratio. Agenesis of all third molars was not associated with significant craniofacial differences.

CONCLUSIONS

Hypodontia is widely prevalent in DS. The effect of the syndrome appears to be stronger than that of regional hypodontia in differentially altering the craniofacial morphology.

Cranial base, maxillary and mandibular morphology in Down syndrome

OBJECTIVE

To test the null hypothesis that there is no difference between craniofacial measurements of individuals with Down syndrome (DS) and normal controls.

MATERIALS AND METHODS

A cephalometric analysis including additional landmarks and measurements to study specific craniofacial features was undertaken on pretreatment cephalograms of 25 patients with DS (12 male, 13 female; mean age 15.1 years) treated at The Hospital for Sick Children, Toronto. Measurements were compared with those from cephalograms of racial groups age and gender matched, normal, Class I children, available from the Burlington Growth Center. Data were analyzed using paired t-tests.

RESULTS

Large reductions were measured in the size and spatial relationships of craniofacial structures in the DS group. The greatest differences included a larger cranial base angle; reduced elevation of sella from FHP; reduced anterior and posterior cranial base lengths; reduced anterior and posterior face heights; smaller maxilla with reduced anterior basal and apical dimensions; and smaller mandibular ramus, body and symphyseal dimensions and proclined symphysis. Maxillary incisors were severely proclined and undererupted, while mandibular incisors were undererupted. Alveolar heights were reduced. Anterior open bite was frequently noted. Maxillary and mandibular planes exhibited forward rotation patterns, promoting overclosure. Mandibular hypoplasia was less severe than cranial base and maxillary hypoplasia. Hypodontia of one or more permanent teeth was found in 92% of the sample.

CONCLUSIONS

The null hypothesis was rejected. Significant hypoplasia in endochondral, mesodermal, and ectomesenchymal derived structures of the cranium and face in subjects with DS was clearly evident. More severe platybasia than previously reported was found.

The morphology of the sella turcica in velocardiofacial syndrome suggests involvement of a neural crest developmental field

We described the morphology of the sella turcica in individuals with velocardiofacial syndrome (VCFS), also known as chromosome 22q11.2 deletion syndrome, and compared the morphology with that of a control group of individuals from the Oslo University Craniofacial Growth Archive. The aim was to measure the cranial base angles in individuals with VCFS and, if possible, to discover the developmental field that may be involved in the condition. The study included 33 patients with VCFS from the Copenhagen Cleft Palate Center, Denmark. The genotype was confirmed by fluorescence in situ hybridization. The morphology of the sella turcica was described and measurements of the cranial base angles were performed on lateral cephalometric radiographs. The VCFS individuals had larger deviations in the morphology of the sella turcica compared to individuals from the Oslo University Craniofacial Growth archive. The deviations were mostly in the posterior part of the dorsum sellae. Individuals with VCFS had increased cranial base angles. The results of this study combined with the information in the literature on the main defects in VCFS (palatal abnormalities, cardiac anomalies, thymic hypoplasia or aplasia, hypothyroidism, and posterior brain abnormality), suggest involvement of a specific developmental field.

Orthodontics and foetal pathology: a personal view on craniofacial patterning

This article summarizes the essentials of studies on the craniofacial skeleton performed over 17 years. It presents data from research into foetal pathology resulting in new views on craniofacial patterning and/or fields for further discussion. The fields described cover all areas seen on profile, frontal, and panoramic radiographs. The fields are the theca, frontonasal, maxillary, palatine, and mandibular together with the cerebellar field and cervical spine. Regional fields in the dentition are described according to the pattern of peripheral nerve innervation. Studies on severely malformed foetuses show that the malformation can occur solely within a single field or in several fields. This is the background for these personal views on craniofacial patterning. These new views may assist in the diagnosis and interpretation of malformations in the cranium and dentition.

Sella Turcica Morphology and Dimensions in Cleft Subjects

Objectives:

Evaluate sella turcica morphology, calculate its size in cleft subjects, and compare it with noncleft subjects.

Materials:

Lateral cephalometric radiographs of 95 cleft and 190 noncleft individuals. Radiographs were divided into two groups by age: 11 to 14 years of age, 15 years and above.

Main Outcome Measures:

The morphology of the sella turcica was categorized into six shapes; whereas, the size of the sella turcica was measured in terms of length, depth, and diameter in millimeters.

Results:

The sella turcica was abnormal in shape in the majority of cleft subjects when compared with noncleft subjects (p  =  .0000), more so in subjects with unilateral cleft lip and palate and bilateral cleft lip and palate (p  =  .0000, p  =  .020, respectively). Depth of sella turcica was smaller in unilateral cleft lip and palate subjects (p  =  .037). A smaller sella turcica size (length, depth, diameter) was evident in cleft subjects as compared with noncleft subjects (p  =  .037, p  =  .004, p  =  .000, respectively). Age correlated positively with an increase in sella turcica size in both noncleft and cleft subjects (p  =  .000, p  =  .009, p  =  .000).

Conclusions:

A majority of cleft subjects displayed an abnormal appearance of sella turcica when compared with noncleft subjects. A smaller depth of sella turcica was associated with unilateral cleft lip and palate. The sella turcica was smaller in size in cleft subjects than in noncleft subjects. Sella turcica size increased with age in subjects with and without clefts.

A cephalometric morphometric study of the sella turcica

The purpose of this study was to use quantitative methods to measure the size and shape of the sella turcica and thus establish normative reference standards that could assist in a more objective evaluation and detection of pathological conditions. Standardized lateral cephalograms of 184 healthy Greeks (91 males and 93 females) were used. The age range was between 6 and 17 years. Conventional measurements included three different heights of the sella turcica (anterior, posterior, median), its length, and width, measured in relation to the Frankfort reference line. In addition, the area of sella turcica was calculated. Morphometric methods were used to assess shape. The tracings were superimposed using the Procrustes method, and the average shape was computed. Principal component analysis (PCA) was used to assess shape variability. The data were correlated with centroid size, age, and gender. Unpaired t-tests were used to determine gender differences. Sella height anteriorly was the only variable found to be significantly different between the genders, being larger in females by 0.5 mm. Linear and area measurements were found to be significantly correlated with age, but all correlations were low (r(2) below 8 per cent). Sella turcica shape, as described by PCA, was different between males and females, mainly at the posterior aspect of the sella outline. However, although there was an extensive overlap between the genders, and differences were minimal. Age was not found to be correlated with the shape coefficients, although, in the female group, the first principal component of shape was marginally not significant. Allometry was observed in both genders, the sella showing a tendency towards a flatter and wider shape with increase in size. The results of this study constitute quantitative reference data that could be used for objective evaluation of sella shape.

Comparison of fetal nasal bone assessment by ultrasound at 11-14 weeks and by postmortem X-ray in trisomy 21: a prospective observational study

OBJECTIVE

To compare nasal bone assessment by ultrasound examination at 11-14 weeks' gestation and postmortem X-ray examination in fetuses with trisomy 21.

METHODS

Twenty-one fetuses with trisomy 21 which had undergone sonographic examination at 11-14 weeks for measurement of nuchal translucency thickness and assessment of the nasal bones were examined by postmortem X-ray following termination of pregnancy.

RESULTS

The nasal bones were absent in 11/21 (52.4%) fetuses on ultrasound examination at 11-14 weeks and in 10/21 (47.6%) fetuses on X-ray examination at 14 to 25 + 5 weeks. Ultrasound and X-ray findings were discordant in 9/21 (42.9%) cases. Eight of 11 (72.7%) fetuses with absent nasal bones on ultrasound examination had a nuchal translucency thickness > 95th centile.

CONCLUSION

The high incidence of absent nasal bones in first-trimester fetuses with trisomy 21 is compatible with a developmental delay. Prior to inclusion of nasal bone assessment into risk calculation for trisomy 21, the independence of absence of nasal bones by ultrasound and increased nuchal translucency above the 95th centile at 11-14 weeks should be investigated more extensively.

A histological and radiological investigation of the nasal bone in fetuses with Down syndrome

OBJECTIVES

Previous studies of nasal bone development in Down syndrome have used radiographs or ultrasound for the detection of nasal bone length or nasal bone absence. The aim of this study was to investigate the presence and size of the nasal bones in postmortem Down syndrome fetuses by means of radiographs and histological examination.

METHODS

Thirty-three aborted human fetuses (gestational age 14-25 weeks) with Down syndrome were included. A mid-sagittal tissue block was excised from the skull base to the foramen magnum and along the lateral aspect of the spine. Radiographs of the tissue block were taken in lateral, frontal and axial projections. The length of the nasal bone was measured. The tissue blocks were cut in serial sections and stained. The crown-rump length (CRL), foot length (FL) and number of ossified bones in the hand and foot (CNO) were recorded.

RESULTS

A total of 8/33 fetuses had bilateral nasal bone absence and two had unilateral absence. In fetuses with radiographically diagnosed nasal bone absence, no nasal bone could be found histologically. The majority of the Down syndrome fetuses had CRL, FL and CNO values within the range of those for normal age-matched fetuses. Nasal bone length was normal or reduced.

CONCLUSIONS

Absence of the nasal bone was registered by postmortem examination in one-third of fetuses with Down syndrome. In some fetuses this could be a result of delayed maturation associated with Down syndrome. The phenotypic differences in nasal bone appearance may reflect genotypic differences in the Down syndrome group.