Morphometry of the cranial base in subjects with Class III malocclusion

Midface hypoplasia in syndromic craniosynostosis: predicting craniofacial growth via a novel regression model from anatomical morphometric analysis

Midface hypoplasia in syndromic craniosynostosis (SC) may lead to serious respiratory issues. The aim of this study was to analyse the morphometric correlation between midface and cranial base parameters in paediatric SC patients in order to formulate predictive regression models. The computed tomography scans of 18 SC patients and 20 control were imported into Materialise Mimics Medical version 21.0 software for the measurement of multiple craniofacial landmarks and correlation analysis. The results showed a strong correlation of anterior cranial base (SN), posterior cranial base (SBa), and total cranial base (NBa) (r = 0.935) to maxilla length and width (ZMR-ZML) (r = 0.864). The model of NBa = - 1.554 + 1.021(SN) + 0.753(SBa) with R2 = 0.875 is proposed to demonstrate the development of the cranial base that causes a certain degree of midface hypoplasia in SC patients. The formula is supported using a prediction model of ZMR-ZML = 5.762 + 0.920(NBa), with R2 = 0.746. The mean absolute difference and standard deviation between the predicted and true NBa and ZMR-ZML were 2.08 ± 1.50 mm and 3.11 ± 2.32 mm, respectively. The skeletal growth estimation models provide valuable foundation for further analysis and potential clinical application.

Comparison of three-dimensional maxillary growth across spheno-occipital synchondrosis maturation stages

BACKGROUND

This study aimed to three-dimensionally compare the maxillary growth among the spheno-occipital synchondrosis (SOS) maturation stages in both genders.

METHODS

This is a cross-sectional study of a retrospective type in which cone-beam computed tomography (CBCT) images of 500 patients aged 6 to 25 years (226 males and 274 females) were analyzed. The SOS was evaluated using the four-stage scoring system; completely open, partially fused, semi-fused, or completely fused. The SOS scoring and three-dimensional cephalometric measurements were analyzed by Invivo 6.0.3 software. Descriptive and analytical statistics were performed and a P-value < 0.05 was considered statistically significant.

RESULTS

There was a statistically significant difference in maxillary measurements among SOS maturation stages in both genders (P < 0.05). The mean differences in the maxillary growth among the SOS maturation stages between SOS stages 2 and 3 were higher than those between stages 1and 2 and stages 3 and 4 for maxillary length and height in both genders. However, the mean difference in the maxillary width was higher between SOS stages 1 and 2 than those stages 2 and 3 and stages 3 and 4. On other hand, there may be lesser maxillary growth between SOS stages 3 and 4 for maxillary width, length (in males), and height. The growth curves showed high active growth of the maxilla as the SOS was still fusing (especially stage 2 and 3) than those of the fused (stage 4). Moreover, the acceleration of growth occurred earlier in females than males regarding chronological age but not for SOS maturation stages.

CONCLUSIONS

The SOS maturation stages are valid and reliable maxillary skeletal maturation indicators for three-dimensional maxillary growth in both genders.

Comparison of spheno-occipital synchondrosis maturation stages with three-dimensional assessment of mandibular growth

BACKGROUND

This study aimed to compare spheno-occipital synchondrosis (SOS) maturation stages with a three-dimensional assessment of mandibular growth.

METHODS

This is a cross-sectional study of a retrospective type, in which cone-beam computed tomography (CBCT) images of 500 patients aged 6 to 25 years (226 males and 274 females) were analyzed. The SOS was evaluated using the four-stage scoring system; completely open, partially fused, semi-fused, or completely fused. The SOS scoring and three-dimensional cephalometric measurements were analyzed by Invivo 6.0.3 software. Descriptive and analytical statistics were performed, and a P-value < 0.05 was considered statistically significant.

RESULTS

There was a statistically significant difference in mandibular measurements among SOS maturation stages in both sexes (P < 0.05). The skeletal growth increments of mandibular variables across the SOS stages had higher mean differences between SOS stages 2 and 3 than those between stages 1 and 2 and stages 3 and 4 in both sexes. The mandibular growth curves increased with chronological age (earlier in females) and SOS maturation stages (mostly in stages 1, 2, and 3 than stage 4).

CONCLUSIONS

The SOS maturation stages are valid and reliable mandibular skeletal indicators as evaluated with three-dimensional cephalometric mandibular measurements. The findings of growth increments and constructed growth curves of mandibular growth might be helpful in diagnosis and treatment planning.

Assessment of Dentofacial Characteristics in Individuals with Different Midfacial Skeletal Morphologies

Introduction An orthodontist's primary objective is to diagnose and describe the characteristics of any particular malocclusion. It has been reported that when the anteroposterior dimension of the maxilla is either reduced or increased, the measured dentoalveolar and skeletal parameters gets affected in other dimensions also.

Aim This study aims to assess and compare the dentofacial characteristics in individuals with different skeletal morphology (normal, retrognathic, and prognathic maxilla).

Materials and Methods A total of 194 individuals in the age group of 18 to 32 years were grouped as group I (34 males, 33 females) with normal maxilla, group II (30 males, 32 females) with retrognathic maxilla, and group III (34 males, 31 females) with prognathic maxilla. The measurements of N-A and anterior nasal spine to posterior nasal spine were the basis for selecting the individuals. The dentoalveolar characteristics were assessed using 17 lateral cephalometric and 08 posteroanterior (P-A) cephalometric parameters.

Results The data of the study when analyzed statistically using sample “t” test (p < 0.05), revealed significant differences between the genders within the groups. All 08 characteristics measured in the P-A cephalogram showed had significant differences. Pairwise comparison between the groups was performed using the Tukey post hoc test (p < 0.05) and significant differences in various dentoalveolar characteristics were observed between the groups.

Conclusion Dentoalveolar and facial parameters showed a significant degree of sexual dimorphism associated with maxillary morphology in all three groups of individuals. The majority of the parameters showed male dominance, and the differences were statistically significant. Statistically significant differences were observed in dentofacial characteristics in individuals with different skeletal morphologies

Virtual Surgical Planning: Modeling from the Present to the Future

Virtual surgery planning is a non-invasive procedure, which uses digital clinical data for diagnostic, procedure selection and treatment planning purposes, including the forecast of potential outcomes. The technique begins with 3D data acquisition, using various methods, which may or may not utilize ionizing radiation, such as 3D stereophotogrammetry, 3D cone-beam CT scans, etc. Regardless of the imaging technique selected, landmark selection, whether it is manual or automated, is the key to transforming clinical data into objects that can be interrogated in virtual space. As a prerequisite, the data require alignment and correspondence such that pre- and post-operative configurations can be compared in real and statistical shape space. In addition, these data permit predictive modeling, using either model-based, data-based or hybrid modeling. These approaches provide perspectives for the development of customized surgical procedures and medical devices with accuracy, precision and intelligence. Therefore, this review briefly summarizes the current state of virtual surgery planning.

Developmental Abnormalities of the Skull Base in Patients with Turner Syndrome

The skull base is one of the most complex anatomic structures of the skeleton that is responsible for protecting and supporting the brain and is also involved in the development of the facial structures. The main objective of our study was to evaluate skull base abnormalities in a group of patients diagnosed with Turner syndrome by assessing lateral cephalometric radiographs. A total of 7 patients diagnosed with Turner syndrome in the Endocrinology Department of the Emergency Clinical County Hospital of Craiova were included in the study. The following cephalometric variables were measured in our study: total skull base (N-Ba): Nasion (N)-Basion (Ba); anterior skull base (N-S): Nasion (N)-Sella (S); posterior skull base (S-Ba): Sella (S)-Basion (Ba). Regarding the investigated cephalometric variables, the mean±standard deviation (SD) recorded values in our study were 86.34±4.26mm for the total skull base (N-Ba), 63.87±2.54mm for the anterior skull base (N-S) and 38.33±4.87mm for the posterior skull base (S-Ba). The results of our study were compared to the ones provided by one of the most representative studies described in the literature. A reduced size of the posterior base of the skull is considered pathognomonic in subjects diagnosed with Turner syndrome. Also, the posterior base of the skull directly influences the maxillomandibular skeletal relationships and it is therefore necessary to calculate this cephalometric variable, which is easily highlighted on a lateral cephalometric radiograph.

Time and pattern of the fusion of the spheno-occipital synchondrosis in patients with skeletal Class I and Class III malocclusion

OBJECTIVES

To investigate the time and pattern of fusion of the spheno-occipital synchondrosis in patients with skeletal Class I and Class III malocclusion using cone-beam computed tomography (CBCT).

MATERIALS AND METHODS

A total of 262 CBCT images were collected: 140 skeletal Class I (0° < ANB < 4°; 71 males, 69 females) and 122 skeletal Class III (ANB ≤ 0°; 61 males and 61 females). The fusion stages were identified using CBCT images of a six-stage system defined by the appearance of osseous cores and ossifying vestige in the synchondrosis. The age distributions of each stage and the pattern of fusion were evaluated.

RESULTS

The stages of fusion progressed with increasing age (P < .05, r = .824), and the age distributions in the female groups were generally 1 to 3 years younger than those in the male groups. However, no significant differences were observed between the skeletal Class I and Class III groups regarding the time of ossification of the synchondrosis. The osseous cores appeared most frequently in the supero-center part, followed by the mid-center part of the synchondrosis.

CONCLUSIONS

The time and pattern of fusion of the spheno-occipital synchondrosis are not apparently different between patients with Class I malocclusion and those with Class III malocclusion. The osseous cores appear frequently in the supero-center and mid-center of the synchondrosis with various patterns before the end of the pubertal growth spurt period.

Influence of the cranial base flexion on Class I, II and III malocclusions: a systematic review

Objective:

The aim of this study was to perform a systematic review on the morphological characteristics of the skull base (flexion, anterior length and posterior length) and the concomitant development of malocclusions, by comparing differences in dimorphism, ethnicity and age.

Methods:

The articles were selected by means of electronic search on BBO, MEDLINE and LILACS databases from 1966 to 2016. A qualitative evaluation of the methodologies used on the articles was also performed.

Results:

Although the literature on this topic is abundant, only 16 articles were selected for the present systematic review. The cranial base angle itself does not seem to play a significant role in the development of malocclusions. In fact, the cranial base angle is relatively stable at the ages of 5 to 15 years.

Conclusions:

A more obtuse angle at the skull base, in association or not with a greater anterior length of the cranial base, can contribute to the development of Class II division 1 malocclusions. On the other hand, a more acute angle at the skull base can contribute to a more anterior positioning of the mandible and to the development of Class III malocclusions.

Appropriate cyclic tensile strain promotes biological changes of cranial base synchondrosis chondrocytes

OBJECTIVES

This study was designed to clarify biological changes of cranial base synchondrosis chondrocytes (CBSCs) upon cyclic tensile strain (CTS) loading which simulated orthopaedic mechanical protraction on cranial base synchondroses (CBS).

MATERIAL AND METHODS

A two-step digestion method was used to isolate CBSCs obtained from 1-week-old Sprague Dawley rats. Immunohistochemical staining of type II collagen and Sox9 was conducted to identify chondrocytes. A CTS of 1 Hz and 10% elongation was applied to the second passage of CBSCs by FX-5000™ Tension System for 24 hours. The control group kept static at the same time. The expression levels of extracellular matrix (Acan, Col1a1, Col2a1 and Col10a1) and key regulatory factors (Sox9, Ihh and PTHrP) were detected by quantitative real-time RT-PCR.

RESULTS

Positive staining of type II collagen and Sox9 was detected in the isolated CBSCs. The relative expression level of Acan, Col2a1, Col10a1, Sox9 and Ihh in the CTS-loading group was 1.85-fold, 2.19-fold, 1.53-fold, 6.62-fold, and 1.39-fold, respectively, as much as that in the control group, which had statistical significance (P<.05). There was no statistical difference (P>.05) in the expression of Col1a1 and PTHrP.

CONCLUSIONS

A CTS of 1 Hz and 10% elongation for 24 hours had positive effects on chondrocyte proliferation, phenotype maintenance and cartilage matrix synthesis.

Longitudinal Craniofacial Growth Patterns in Patients with Orofacial Clefts: Geometric Morphometrics

Objective

To demonstrate craniofacial developmental patterns in repaired cleft lip and cleft palate (CLP).

Design

Retrospective, longitudinal.

Setting

Center for Craniofacial Disorders, San Juan, Puerto Rico.

Sample

Males aged 9 to 17 years: 13 noncleft (NC) Class I occlusion (NCC1); 13 NC Class III malocclusion (NCC3); 12 CLP Class I occlusion (CLPC1); and 15 CLP Class III malocclusion (CLPC3).

Main Outcome Measures

Form changes (ages 10, 13, and 16 years), using finite-element scaling analysis.

Results

NCC1, 10 to 13 interval: 30% size increase in upper midface (p < .05), mental region (p < .01), mandibular body (p < .05); 13 to 16 interval: 10% to 35% size increase in bimaxillary region and ramus (p < .01). NCC3, 10 to 13 interval: 10% to 40% size increase in posterior cranial base, upper midface, and mandible (p < .05); 13 to 16 interval: 10% to 30% size increase in bimaxillary region (p < .01), especially ramus. CLPC1, 10 to 13 interval: 10% to 15% size increase in posterior cranial base (p < .01), midface (p < .05), and mandibular ramus (p < .05); 13 to 16 interval: 8% to 20% size increase in upper midface (p < .01), lower midface (p < .05), and mandible (p < .05). CLPC3, 10 to 13 interval: no significant changes; 13 to 16 interval: upper midface and cranial base show nonsignificant size decreases, but ramus showed size increase.

Conclusions

Noncleft and CLP Class 1 occlusion groups show similar craniofacial growth patterns. Noncleft Class III groups show excessive cranial and mandibular growth. Class III malocclusion in CLP patients is associated with clinically deficient craniomaxillary growth. Growth guidance may be indicated in children with CLP with unfavorable craniofacial growth patterns.

Cranial base characteristics in anteroposterior malocclusions: A meta-analysis

OBJECTIVE

To investigate cranial base characteristics in malocclusions with sagittal discrepancies.

MATERIALS AND METHODS

An electronic search was performed in PubMed, Embase, Web of Science, and the Cochrane Library. A fixed- or random-effect model was applied to calculate weighted mean difference with 95% confidence intervals (CIs) according to statistical heterogeneity. Outcome measures were anterior, posterior, and total cranial base length and cranial base angle. Sensitivity analysis and publication bias were conducted.

RESULTS

Twenty studies that together included 1121 Class I, 1051 Class II, and 730 Class III cases qualified for the final analysis. Class III malocclusion demonstrated significantly reduced anterior (95% CI: -1.74, -0.53; P < .001 vs Class I; 95% CI: -3.30, -2.09; P < .001 vs Class II) and total cranial base length (95% CI: -3.33, -1.36; P < .001 vs Class I; 95% CI: -7.38, -4.05; P < .001 vs Class II). Further, Class II patients showed significantly greater anterior and total cranial base length than did Class I patients (95% CI: 0.51, 1.87; P < .001 for SN; 95% CI: 2.20, 3.30; P < .001 for NBa). Cranial base angle was significantly smaller in Class III than in Class I (95% CI: -3.14, -0.93; P < .001 for NSBa; 95% CI: -2.73, -0.68; P  =  .001 for NSAr) and Class II malocclusions (95% CI: -5.73, -1.06; P  =  .004 for NSBa; 95% CI: -6.11, -1.92; P < .001 for NSAr) and greater in Class II than in Class I malocclusions (95% CI: 1.38, 2.38; P < .001 for NSBa).

CONCLUSIONS

This meta-analysis showed that anterior and total cranial base length and cranial base angle were significantly smaller in Class III malocclusion than in Class I and Class II malocclusions, and that they were greater in Class II subjects compared to controls.

Cranial-base morphology in adults with skeletal Class III malocclusion

INTRODUCTION

The objectives of this study were to clarify the characteristics of cranial-base morphology in adults with skeletal Class III malocclusion and investigate factors relating to the establishment of a skeletal Class III malocclusion.

METHODS

Initial lateral cephalograms of women were examined. Subjects with an ANB angle of 0° to 4°, normal overjet and overbite, and a Class I molar relationship were classified as Class I (n = 86). Those with an ANB angle less than -1°, a Wits appraisal less than 2 mm, a negative overjet, and a Class III molar relationship were the Class III group (n = 86) in this study. Angular, linear, and coordinate measurements were made. Multivariate analysis of variance and the Student t test were used to analyze significant differences between the 2 groups. Discriminant analysis, logistic regression analysis, and decision analysis were used to identify which cranial-base and maxillomandibular variables influenced the establishment of a skeletal Class III malocclusion.

RESULTS

The Class III group had smaller values for NSBa, SeSBa, FH-SSe, and FH-SBa. Sphenoidale and basion were more inferior and anterior than those of the Class I group. There was no difference in the anterior and posterior cranial-base lengths between the groups. Greater mandibular length was the first major characteristic in the Class III group, followed by smaller values for SeSBa and NSBa.

CONCLUSIONS

Cranial-base morphology in adults with a skeletal Class III malocclusion is different from that in a skeletal Class I malocclusion. Smaller cranial-base angles, steeper posterior cranial bases, more inferiorly positioned sphenoidale, and more anteriorly positioned basion are major characteristics of skeletal Class III malocclusions. These characteristics play important roles in the establishment of a skeletal Class III malocclusion.

A computerized tomography study of the morphological interrelationship between the temporal bones and the craniofacial complex

The hypothesis that the temporal bones are at the center of the dynamics of the craniofacial complex, directly influencing facial morphology, has been put forward long ago. This study examines the role of the spatial positioning of temporal bones (frontal and sagittal inclination) in terms of influencing overall facial morphology. Several 3D linear, angular and orthogonal measurements obtained through computerized analysis of virtual models of 163 modern human skulls reconstructed from cone-beam computed tomography images were analyzed and correlated. Additionally, the sample was divided into two subgroups based on the median value of temporal bone sagittal inclination [anterior rotation group (n = 82); posterior rotation group (n = 81)], and differences between groups evaluated. Correlation coefficients showed that sagittal inclination of the temporal bone was significantly (P < 0.01) related to midline flexion, transversal width and anterior-posterior length of the basicranium, to the anterior-posterior positioning of the mandible and maxilla, and posterior midfacial height. Frontal inclination of the temporal bone was significantly related (P < 0.01) to basicranium anterior-posterior and transversal dimensions, and to posterior midfacial height. In comparison with the posterior rotation group, the anterior rotation group presented a less flexed and anterior-posteriorly longer cranial base, a narrower skull, porion and the articular eminence located more superiorly and posteriorly, a shorter posterior midfacial height, the palatal plane rotated clockwise, a more retrognathic maxilla and mandible, and the upper posterior occlusal plane more inclined and posteriorly located. The results suggest that differences in craniofacial morphology are highly integrated with differences in the positional relationship of the temporal bones. The sagittal inclination of the temporal bone seems to have a greater impact on the 3D morphology of the craniofacial complex than frontal inclination.

Orthopedic protraction of the maxilla may affect cranial base synchondroses indicated by increased expressions of growth factors

OBJECTIVES

To examine the biological adaptation of cranial base synchondroses (CBS) when the maxilla was forward positioned by orthopedic force.

SETTING AND SAMPLE POPULATION

The Department of Orthodontics at Shanghai Jiao Tong University. 50 Sprague-Dawley rats, 4 weeks of age, were divided into experimental (n=30) and control groups (n=20).

MATERIAL AND METHODS

An orthopedic appliance was fitted to the cranio-maxillary complex to advance the maxilla forward. The animals in the experimental group, together with the counterparts in the control group, were sacrificed at days 1, 3, 5, 7, and 14, respectively. The whole cranial base housing both the spheno-ethmoid (SES) and spheno-occipital synchondroses (SOS) was removed for tissue processing and immunotest of Sox9, Core-binding factor α 1 (Cbfa1), and vascular endothelial growth factor (VEGF), three carefully selected growth factors that are markers of chondrogenesis in different stages and its transition to endochondral ossification. Semiquantitative analysis was also conducted by using a computerizing imaging system.

RESULTS

The temporal tendency of the changes in the expressions of the three growth factors featured an increase from Day 3 and onwards for Cbfa1 and VEGF, and a following decline after Day 5 for Sox9. In both SES and SOS, the expressions of the three growth factors were significantly stronger in the experimental groups than that in groups (p<0.05).

CONCLUSIONS

Protractive orthopedic force imposed on the maxilla provokes an enhancement of chondrogenic process in CBS.

Inheritance of craniofacial features in Colombian families with class III malocclusion

Introduction

The inheritance of class III malocclusion has been well documented, but the inheritance of craniofacial structures in Colombian families with this malocclusion has been not yet reported.

Patients and methods

The study sample of 25 families comprised 186 untreated orthodontic individuals from 8 to 60 years old. Pedigrees were drawn using Cyrillic software. Complete family histories for each proband were ascertained and the affection status of relatives was confirmed by lateral cephalograms and facial and dental photographs. Analysis of variance and odds ratio test for each parameter was performed to estimate inheritance from parents to offspring and to determine similar phenotypic features in relatives.

Results

The analysis of the pedigrees suggests autosomal dominant inheritance. The craniofacial characteristics that showed more resemblance between parents and offspring were middle facial height, shorter anterior cranial base and mandibular prognathism. In contrast the protrusion of upper lip and maxillary retrusion were the phenotypic features that contributed to class III in the majority of families.

Conclusion

Knowledge of the inheritance of craniofacial phenotypes in class III malocclusion will enable the design of new therapies to treat this malocclusion.

Induced premaxillary suture fusion: class III malocclusion model

The etiology of class III malocclusion remains unknown. The present study investigates the relationship between craniofacial morphology and premaxillary suture fusion to test the hypothesis that class III malocclusion may be related to premaxillary suture fusion. Cyanoacrylate was applied to immobilize the left premaxillary suture in the experimental group. Sham surgeries in rats were used for controls. Dental impressions and radiographs were taken before and after surgery for comparison of craniofacial differences between groups. Overall cranial base lengths, craniofacial widths, and craniofacial angulations related to the anterior base showed significant differences between groups. At the end of the experiment, the growth of the snout in the experimental group was inhibited and deviated to the treated side, while no obvious change was seen in the control group. The results show that induced premaxillary suture fusion can affect craniofacial morphology and indicate that premature premaxillary suture fusion may result in class III malocclusion.

Cranial base features in skeletal Class III patients

OBJECTIVE

To investigate the cranial base configuration in skeletal Class III patients to clarify the conflicting findings from literature.

MATERIALS AND METHODS

Initial lateral radiographs of 54 skeletal Class III patients and 54 matched controls (Class I, II/1, II/2) aged 14 to 24 years were analyzed retrospectively for 21 cephalometric basicranial variables and jaw lengths relative to anterior cranial base length.

RESULTS

In contrast to overall cranial base length, the anterior (N-S) and posterior (S-Ba, S-Ar) sections failed to show a significant reduction in Class III patients. The significantly more acute angles Ca-S-Ba and Se-S-Ba reflected increased cranial base flexure. Resulting anterior condylar displacement was shown by significant reduction of Se-S-Cd and Ar-Ca. Relative mandibular length was significantly increased.

CONCLUSIONS

Decreased basicranial angulation associated with Class III mandibular protrusion was clearly confirmed for skeletal Class III patients. Overall shortening of the cranial base apparently resulted from various minor alterations. The results are compatible with the deficient orthocephalization hypothesis of Class III morphogenesis. The basicranial-maxillary relationship in skeletal Class III remains unclear.

Craniofacial morphometric analysis of mandibular prognathism

The purpose of this study was to provide more information about the morphological characteristics of the craniofacial complex in mandibular prognathism. Forty young adult males having mandibular prognathism were compared with 40 having normal occlusion. This was conducted to carry out geometric morphometric assessments to localize alterations, using Procrustes analysis and thin-plate spline analysis, in addition to conventional cephalometric techniques. Procrustes analysis indicated that the mean craniofacial, midfacial and mandibular morphology was significantly different in prognathic subjects compared with normal controls. This finding was corroborated by the multivariate Hotelling T(2)-test of cephalometric variables. Mandibular prognathism demonstrated a shorter and slightly retropositioned maxilla, a greater total length and anterior positioning of the mandible. Thin-plate spline analysis revealed a developmental diminution of the palatomaxillary region anteroposteriorly and a developmental elongation of the mandible anteroposteriorly, leading to the appearance of a prognathic mandibular profile. In conclusion, thin-plate spline analysis seems to provide a valuable supplement for conventional cephalometric analysis because the complex patterns of craniofacial shape change are visualized suggestive by means of grid deformations.

Morphometric Analysis of Mandibular Growth in Skeletal Class III Malocclusion

BACKGROUND

The craniofacial growth patterns of untreated individuals with skeletal Class III malocclusion have rarely been systemically investigated. This study used morphometric techniques to investigate the growth characteristics of the mandible in individuals with skeletal Class III malocclusion.

METHODS

Lateral cephalometric head films of 294 individuals with untreated skeletal Class III malocclusion (134 males, 160 females) were selected and divided into five triennial age groups (T1-T5) and by gender to identify the morphologic characteristics and sexual dimorphism in changes of mandibular growth. Procrustes, thin-plate spline, and finite element analyses were performed for localization of differences in shape and size changes. Maximum and minimum principal axes were drawn to express the directions of shape changes.

RESULTS

From T1 (age 6-8 years) to T4 (age 15-17 years), the distribution of localized size and shape changes of the mandible was very similar between the two genders. From T1 to T2 (age 9-11 years), significant lengthening of the condylar region was noted (23.4-39.7%). From T2 to T3 (age 12-14 years), the greatest size and shape change occurred at the condylar head (27.4-34.9%). From T3 to T4, the greatest size and shape changes occurred in the symphyseal region (23.6-42.1%). From T4 to T5 (age>or=18 years), significant sexual dimorphism was found in the distribution and amount of localized size and shape changes. Females displayed little growth increments during T4. Despite differences in the remodeling process, the whole mandibular configurations of both genders exhibited similarly significant upward and forward deformation from T4 to T5.

CONCLUSION

We conclude that thin-plate spline analysis and the finite element morphometric method are efficient for the localization and quantification of size and shape changes that occur during mandibular growth. Plots of maximum and minimum principal directions can provide useful information about the trends of growth changes.

Cranial base in craniofacial development: developmental features, influence on facial growth, anomaly, and molecular basis

The cranial base is of crucial importance in integrated craniofacial development. As distinct from facial bones, it is formed through endochondral ossification. The posterior and anterior cranial bases are derived from distinct embryologic origins and grow independently--the anterior cranial base solely from the neural crest, the posterior cranial base from the paraxial mesoderm. The anterior cranial base has more prolonged and active growth and exerts more influence on facial growth than does the posterior cranial base. Cranial base angulation is a unique feature in modern human beings. Cranial base anomalies have been identified in many genetic and developmental disorders. The molecular basis of cranial base development and growth is being clarified. In this review, these aspects of cranial base are discussed in detail, with a focus on developmental features, roles in craniofacial growth, anomalies, and the genetic basis of development.

Evaluation of facial soft tissue changes with optical surface scan after surgical correction of Class III deformities

PURPOSE

To evaluate the soft tissue changes after correction of Class III dentoskeletal deformity with orthognathic surgery using the optical surface scanner as a 3-dimensional imaging tool and thin-plate splines as a morphometric analysis.

PATIENTS AND METHODS

Forty-six patients with Class III dentoskeletal relationship who underwent a bimaxillary orthognathic surgical procedure involving advancement of the maxilla and mandibular setback to correct the deformity and create a Class I dentoskeletal relationship were included. Optical surface scans (lasergraphs) were obtained from all patients preoperatively and 6 months postoperatively. They were evaluated for the soft tissue changes 3-dimensionally and on the profile line. The cephalographs taken pre- and postoperatively were digitized and evaluated using the CogSoft digitizing software (Consultant Orthodontists Group Software, Bristol, United Kingdom) to confirm whether the preoperative surgical plan was applied.

RESULTS

The soft tissue change in different areas of the face ranged from 30% on the nasal tip to 80% on subnasale and from 50% on subcomissural region corresponding to lateral parts of the mandibular body to 100% on the pogonion. The direction of soft tissue movement was not solely forwards and backwards on a horizontal plane but had upward and downward vectors.

CONCLUSIONS

The soft tissue changes following orthognathic surgery depend on various factors; hence it can be difficult to predict. However, there is a general trend as discussed in this study for the direction and amounts of facial soft tissue changes in the middle and lower facial thirds.

Finite element growth analysis for the craniofacial skeleton in patients with cleft lip and palate

The purpose of this study was to clarify the differences in the nature of craniofacial growth between subjects with normal occlusion and patients with unilateral cleft lip and palate (CLP) in terms of the size, shape and principal growth direction of craniofacial skeleton using finite element method (FEM). Lateral cephalograms were taken of 40 subjects as normal group and 178 patients as CLP group. These subjects were divided into seven developmental ages of 4-, 6-, 8-, 10-, 12-, 14- and 18-year-old. For the finite element analysis, the craniofacial complex was discretized into seven structures or elements with three nodal points in each after tracing each lateral cephalogram on acetate paper. For each stage, the growth parameters in CLP group were compared to those in normal group. The growth of upper facial skeleton and maxillary complex was more remarkably inhibited in CLP than in normal group. Especially, the growth inhibition of posterior maxillary complex in a vertical direction was remarkable in CLP group at any ages. Difference in the size and shape of entire mandibular skeleton between CLP and normal groups was not apparent. It is suggested that grow timing and peak velocity, an essential and key determinant to the success in orthodontic treatment, have been clarified in this study more clearly than in previous studies. It is hopefully anticipated to explore some key determinants to predict individual growth of the craniofacial skeleton near future.

Are collimated low-dose digital radiographs valid for performing Delaire's architectural analysis?

Computed radiography (CR) provides the dynamic exposure range to reveal objects in film areas exposed by very low X-ray exposure. Conventional cephalometric radiographs are normally beam limited to the facial skeleton. The cranial vault and cervical vertebra are collimated and only exposed by extra-focal radiation and scatter. We hypothesize that, on conventional cephalometric radiographs obtained with CR, image data of collimated film areas can be enhanced for reliable performance of Delaire's cephalometric analysis of the entire skull. Therefore the aim of the present study was to compare the reproducibility of landmark placement on normal and underexposed film areas of CR images. Intra- and inter-observer reproducibility of landmark identification was evaluated on 200 randomly selected radiographs by calculating the error radius of repeated landmark placements. A paired-samples t-test revealed differences (P< 0.001) between intra- and inter-observer reproducibility. Intra-observer accuracy was influenced (P< 0.001) by variability of suture obliteration (bregma). Identification of landmarks in areas of extra-focal radiation showed no difference (P> 0.05) from that of landmarks inside the normally exposed area. CR offers the opportunity to perform of a full cranial analysis on a cephalometric radiograph collimated to the facial region.

Effects of the headgear-activator Teuscher appliance in the treatment of Class II Division 1 malocclusion: a geometric morphometric study

OBJECTIVES

To test the hypothesis that there are no gender differences in the outcomes of patients with class II malocclusion treated with the headgear-activator Teuscher appliance (HATA).

DESIGN

Retrospective, longitudinal

SETTING AND SAMPLE POPULATION

Puerto Rico and Scotland, UK. Thirty-one patients requiring correction of class II division 1 malocclusions.

EXPERIMENTAL VARIABLE

Male and female patients treated using HATA.

OUTCOME MEASURES

Mean pre- and post-treatment parameters derived from cephalometry subjected to t-tests, and finite-element scaling analysis (FESA), which localizes and quantifies differences between mean pre- and post-treatment configurations.

RESULTS

Post-treatment, cephalometry showed that for both males and females, angle SNA decreased, SNB increased, and lower facial heights increased significantly (p < 0.01). For the female post-treatment configuration, FESA revealed large size increases (approximately 20%) located in the inter-maxillary region, the ramus and mandibular body, and around the nasal and mental regions. Conversely, the lip region was diminished (approximately 20%). Similarly, male post-treatment showed size increases located in the inter-maxillary region that extended into the nasal region and the mandibular body (approximately 10-15%), and around the chin (15%). The lip region was diminished (approximately 5%).

CONCLUSION

In the attainment of a normal occlusion, both male and female patients treated for class II malocclusions using HATA exhibit antero-posterior restraint of the maxilla, improvements in the mandible maintaining facial height, and lip changes commensurate with improvements in the soft tissue profile.

Mandibular transformations in prepubertal patients following treatment for craniofacial microsomia: thin-plate spline analysis

To analyze correction of mandibular deformity using an inverted L osteotomy and autogenous bone graft in patients exhibiting unilateral craniofacial microsomia (CFM), thin-plate spline analysis was undertaken. Preoperative, early postoperative, and approximately 3.5-year postoperative posteroanterior cephalographs of 15 children (age 10+/-3 years) with CFM were scanned, and eight homologous mandibular landmarks digitized. Average mandibular geometries, scaled to an equivalent size, were generated using Procrustes superimposition. Results indicated that the mean pre- and postoperative mandibular configurations differed statistically (P<0.05). Thin-plate spline analysis indicated that the total spline (Cartesian transformation grid) of the pre- to early postoperative configuration showed mandibular body elongation on the treated side and inferior symphyseal displacement. The affine component of the total spline revealed a clockwise rotation of the preoperative configuration, whereas the nonaffine component was responsible for ramus, body, and symphyseal displacements. The transformation grid for the early and late postoperative comparison showed bilateral ramus elongation. A superior symphyseal displacement contrasted with its earlier inferior displacement, the affine component had translocated the symphyseal landmarks towards the midline. The nonaffine component demonstrated bilateral ramus lengthening, and partial warps suggested that these elongations were slightly greater on the nontreated side. The affine component of the pre- and late postoperative comparison also demonstrated a clockwise rotation. The nonaffine component produced the bilateral ramus elongations-the nontreated side ramus lengthening slightly more than the treated side. It is concluded that an inverted L osteotomy improves mandibular morphology significantly in CFM patients and permits continued bilateral ramus growth.

Euclidean distance matrix analysis of surgical changes in prepubertal craniofacial microsomia patients treated with an inverted L osteotomy

OBJECTIVES

Correction of craniofacial microsomia (CFM) presents several challenges concerning the modality of surgical intervention. The aim of this study was to assess early and late surgical outcome, by undertaking Euclidean distance matrix analysis (EDMA) of CFM patients exhibiting an unilateral mandibular deformity that was surgically corrected by an inverted L osteotomy and autogenous bone graft.

DESIGN

Longitudinal study. Preoperative, approximately =1-year postoperative and approximately 3-year postoperative assessments of 14 consecutive children (mean age 9 years) with CFM. Posteroanterior cephalographs were scanned and five homologous mandibular landmarks were digitized in triplicate (< 1% digitization error). Average mandibular geometries, scaled to an equivalent size, were generated using a generalized rotational fit program (Procrustes superimposition) and subjected to EDMA.

RESULTS

The mean pre- and both postoperative mandibular configurations differed statistically (p < .01). Early postoperative improvements in mandibular form were noted; increases in length arising in the treated mandibular body (approximately =19%) and ramus (approximately =13%). Comparing early and late postoperative configurations, a decrease of approximately =22% in the late postoperative mandibular body length was evident, but the ramus maintained steady vertical growth (approximately =7%). Comparing the preoperative and late postoperative configurations, the decrease observed in the mandibular body on the treated side was reduced to approximately =8% while the ramus maintained good growth (approximately =20%) on that side.

CONCLUSION

Mandibular morphology is improved significantly in CFM patients surgically treated by an inverted L osteotomy, but relapse in the mandibular body is evident after approximately =3 years. Nevertheless, ramus growth proceeds well after the surgical reconstruction.

Morphometry of the midfacial complex in subjects with class III malocclusions: Procrustes, Euclidean, and cephalometric analyses

The purpose of this study was to determine whether the morphology of the midface differed in subjects with a retrognathic midfacial appearance (Class III malocclusions) using a combination of morphometric and cephalometric analyses. After obtaining appropriate consent, lateral cephalographs of 133 children of European-American descent, ages 5-11 years, were compared: 73 had Class III malocclusion, 60 had normal (Class I) occlusion. The cephalographs were traced and subdivided into seven age- and sex-matched groups. Average geometries based upon seven nodes (pterygoid point, PTS; rhinion, RO; posterior nasal spine, PNS; midpalatal point, MPP; anterior nasal spine, ANS; subspinale, A; prosthion, Pr), scaled to an equivalent size, were compared using a Procrustes routine. Euclidean distance matrix analysis (EDMA) was employed to localize differences in morphology. Bivariate analyses on unscaled data utilizing nine linear and six angular measurements were also undertaken. Results from Procrustes and EDMA analyses indicated that although the overall midfacial configurations differed statistically (P < 0.05), only about half of the seven age sub-groups maintained significance. Similarly, only four of the nine linear measures (PNS-MPP, MPP-ANS, A-Pr and PTS-RO) and two of the six angular parameters (PTS-RO-ANS and ANS-A-Pr) tested were significantly different (P < 0.05). Therefore, midfacial morphometric variability and morphological diversity may mask statistical differences. It is concluded that the midface may be the defining craniofacial component in the final appearance of Class III malocclusions compared to other craniofacial components, including the cranial base and mandible.

Morphologic determinants in the etiology of class III malocclusions: a review

Morphospatial disharmony of the craniomaxillary and mandibular complexes may yield apparent mandibular prognathism, but Class III malocclusions can exist with any number of aberrations of the craniofacial complex. Deficient orthocephalization of the cranial base allied with a smaller anterior cranial base component has been implicated in the etiology of Class III malocclusions. Whereas the more acute cranial base angle may affect the articulation of the condyles resulting in their forward displacement, the reduction in anterior cranial size may affect the position of the maxilla. As well, intrinsic skeletal elements of the maxillary complex may be responsible for maxillary hypoplasia that may exacerbate the anterior crossbite seen in the Class III condition. Conversely, with an orthognathic maxilla, condylar hyperplasia and anterior positioning of the condyles at the temporo-mandibular joint may produce an anterior crossbite. Aside from the skeletal components, soft tissue matrices, particularly labial pressure from the circumoral musculature, may influence the final outcome of craniofacial growth of a child skeletally predisposed to Class III conditions. Indeed, as some Asian ethnic groups demonstrate an increased prevalence of Class III malocclusions, it is likely that the skeletal components and soft tissues matrices are genetically determined. Presumably, the co-morphologies of the craniomaxillary and mandibular complexes are likely dependent upon candidate genes that undergo gene-environmental interactions to yield Class III malocclusions. The identification of such genes is a desirable step in unraveling the complexity of Class III malocclusions. With this knowledge, the clinician may elect an early course of dentofacial orthopedic and orthodontic treatments aimed at preventing the development of Class III malocclusions.

Spatial and temporal distribution of cellular proliferation in the cranial base of normal and midfacially retrusive mice

The craniofacial region of the Brachyrrhine (Br) mouse is characterized by a retruded midface. The cellular mechanism causing this growth deficiency is unknown. However, the cranial base is foreshortened in adult Br mice. The purpose of this study was to determine whether the spatial and temporal patterns of cellular proliferation in the cranial base (CB) differ between normal (C3H/HeJ) and Br mutant (3H1 Br/+) embryonic mice. Twenty-four dams were injected (3)H thymidine (5 microCi/gram body weight) and 15 embryos from each group were collected at Theiler stages 23, 25, and 27 (15, 17, and 19 days of gestation). Serial sections from each head were processed with routine autoradiography. Labelling indices (LI) were determined for each specimen and cellular proliferation maps were generated for each age group. LI patterns within and between groups were compared statistically. Results showed that cellular proliferation in the CB of normal embryos displayed a time- and position-dependent pattern, characteristic of transient growth sites (TGS). Generally, as age increases, cellular proliferative activities decrease gradually (from an average LI of 11.4 +/- 5.7% at stage 23 to 4.4 +/- 2.2% at stage 27), and the number of the TGS decreases in the presumptive nasal septal region and increases in presumptive sphenoethmoidal area with age, indicating the existence of cellular subpopulations in the CB. Cellular proliferation in the CB of the Br mutant displays a different growth pattern compared to the normal condition. Deficiencies in cellular proliferation exist mainly in the presumptive sphenoethmoidal area of the CB. The results indicate that the TGS play an important role in the normal morphogenesis of the CB, and abnormalities in their timing and/or position may be responsible for the dysmorphology of the midface in the Br mutant.

Procrustes, Euclidean and cephalometric analyses of the morphology of the mandible in human Class III malocclusions

The role of mandibular phenotype in the development of Class III malocclusion remains unclear. The purpose of this study was to determine whether the form of the mandible differed between prepubertal individuals with Class I and Class III malocclusions. Lateral cephalographs of 73 children of European-American descent aged between 5-11 years with Class III malocclusion were compared to those of 60 counterparts with a normal, Class I molar occlusion. The cephalographs were traced and checked, and eight homologous mandibular landmarks were digitized. Average mandibular geometries, scaled to an equivalent size, were generated using Procrustes superimposition. Euclidean distance matrix analysis (EDMA) was undertaken to corroborate the Procrustes analysis, and bivariate analysis utilizing eight linear and five angular measurements was also performed. Residuals and F-values from Procrustes analysis indicated that mandibular configurations differed statistically for Class I and Class III types. EDMA confirmed that the Class I and Class III geometries were significantly different, revealing that the greatest differences in morphology arose in the anterior-most mandibular regions. As well, most variables showed statistically significant differences when the Class I and Class III mandibular types were compared. When the sample was subdivided into seven age- and sex-matched groups, nearly all age-based comparisons were significantly different. It is concluded that the morphology of the mandible differs in individuals with Class III malocclusions when compared to the normal Class I configuration, and that these alterations may indicate dichotomous postnatal mandibular ontogeny.

Prediction of liability to orofacial clefting using genetic and craniofacial data from parents

BACKGROUND

Cleft lip with or without cleft palate (CL(P)) and isolated cleft palate (CP) are separate clinical entities and for both polygenic multifactorial aetiology has been proposed. Parents of children with orofacial clefting have been shown to have distinctive differences in their facial shape when compared to matched controls.

OBJECTIVE

To test the hypothesis that genetic and morphometric factors predispose to orofacial clefting and that these markers differ for CL(P) and CP. Methods-Polymorphisms at the transforming growth factor alpha (TGFalpha) locus in 83 parents of children with nonsyndromic orofacial clefts were analysed, and their craniofacial morphology was assessed using lateral cephalometry.

RESULTS

Parents of children with CL(P) and CP showed an increased frequency of the TGFalpha/TaqI C2 allele (RR=4.10, p=0.009) relative to the comparison group. Also the TGFalpha/BamHI A1 allele was more prevalent in the CP parents. MULTIVARIATE STATISTICAL ANALYSIS: Using stepwise logistic regression analysis the TGFalpha/TaqI C2 polymorphism provides the best model for liability to orofacial clefting. To determine the type of clefting a model involving interaction between the parental TGFalpha/BamHI and TGFalpha/RsaI genotypes showed the best fit. Using genotype only to predict the clefting defect in the children according to parental genotype, 68.3% could be correctly classified. By adding information on craniofacial measurements in the parents, 76% of CP and 94% of CL(P) parents could be correctly classified.

CONCLUSIONS

This study provides a model for prediction of liability to orofacial clefting. These findings suggest that different molecular aberrations at the TGFalpha locus may modify the risk for CP and CL(P).

Localisation of deformations of the midfacial complex in subjects with class III malocclusions employing thin-plate spline analysis

This study determines deformations of the midface that contribute to a class III appearance, employing thinplate spline analysis. A total of 135 lateral cephalographs of prepubertal children of European-American descent with either class III malocclusions or a class I molar occlusion were compared. The cephalographs were traced and checked, and 7 homologous landmarks of the midface were identified and digitised. The data sets were scaled to an equivalent size and subjected to Procrustes analysis. These statistical tests indicated significant differences (P < 0.05) between the averaged class I and class III morphologies. Thinplate spline analysis indicated that both affine and nonaffine transformations contribute towards the total spline for the averaged midfacial configuration. For nonaffine transformations, partial warp 3 had the highest magnitude, indicating the large scale deformations of the midfacial configuration. These deformations affected the palatal landmarks, and were associated with compression of the midfacial complex in the anteroposterior plane predominantly. Partial warp 4 produced some vertical compression of the posterior aspect of the midfacial complex whereas partial warps 1 and 2 indicated localised shape changes of the maxillary alveolus region. large spatial-scale deformations therefore affect the midfacial complex in an anteroposterior axis, in combination with vertical compression and localised distortions. These deformations may represent a developmental diminution of the palatal complex anteroposteriorly that, allied with vertical shortening of midfacial height posteriorly, results in class III malocclusions with a retrusive midfacial profile.

Spline analysis of the mandible in human subjects with class III malocclusion

This study determines deformations that contribute to a Class III mandibular morphology, employing thin-plate spline (TPS) analysis. A total of 133 lateral cephalographs of prepubertal children of European-American descent with either a Class I molar occlusion or a Class III malocclusion were compared. The cephalographs were traced and checked, and eight homologous landmarks on the mandible were identified and digitized. The datasets were scaled to an equivalent size and subjected to statistical analyses. These tests indicated significant differences between average Class I and Class III mandibular morphologies. When the sample was subdivided into seven age and sex-matched groups statistical differences were maintained for each group. TPS analysis indicated that both affine (uniform) and non-affine transformations contribute towards the total spline, and towards the average mandibular morphology at each age group. For non-affine transformations, partial warp 5 had the highest magnitude, indicating large-scale deformations of the mandibular configuration between articulare and pogonion. In contrast, partial warp 1 indicated localized shape changes in the mandibular symphyseal region. It is concluded that large spatial-scale deformations affect the body of the mandible, in combination with localized distortions further anteriorly. These deformations may represent a developmental elongation of the mandibular corpus antero-posteriorly that, allied with symphyseal changes, leads to the appearance of a Class III prognathic mandibular profile.

Finite element analysis of the cranial base in subjects with Class III malocclusion

The association between cranial base morphology and Class III malocclusion is poorly understood. This study analyses local shape- and size differences in cranial base configurations of Class I and Class III subjects, employing finite element (FEM) analysis. Seventy-three prepubertal European-American children with Class III malocclusion were compared to their counterparts with a normal, Class I molar occlusion. Lateral cephalographs were traced, checked and subdivided into age- and sex-matched groups. Thirteen points on the cranial base were identified and digitized, providing a geometrical cranial base representation. Average cranial geometries were scaled to an equivalent size and a FEM analysis, capable of depicting and quantifying local shape- and size-change, employed to highlight regionalized, morphological differences. While the anterior cranial base was more homogeneous for shape-change, significant, localized anisotropy in the posterior regions of the cranial base and around sella turcica was evident. For size-change, areas of negative allometry were located posteriorly, but dilations in the mid- and anterior cranial base also were apparent. It is concluded that morphological alterations within the petro-occipital complex accompanied by changes in the sphenoidal and ethmoidal regions induce deviation from a normal cranial base configuration to one associated with deficient orthocephalization and an appearance of Class III malocclusion.