A polynomial approach to craniofacial growth: description and comparison of adolescent males with normal occlusion and those with untreated Class II malocclusion

Assessment of chin morphology in different skeletal dysplasia – A cross-sectional study

Objective:

The objective of the study is to evaluate the morphology of the symphyseal region of adult skeletal Class II and Class III malocclusion as compared with Skeletal Class I subjects.

Materials and Methods:

The symphyseal width and height were evaluated using data from 80 lateral cephalograms of the age range of 18 years to 25 years. Average growing Skeletal Class II (n = 30) and Class III (n = 20) subjects were used as a comparison group. Average growing normal occlusion samples (n = 30) were used as controls.

Results:

Alveolar height was similar in all groups. The width of the symphyseal region including basal width, the width of the cervical region of the lower central incisor at the cementoenamel junction, and symphysis width were found to be similar in all groups. There is no significant difference in gonial angle in both Class II and III groups as compared to control. Articular angle showed no significant difference. Mandibular incisor dentoalveolar height (L1-AH) was found to be significantly higher in the Class II group (P < 0.05).

Conclusions:

There are no definite morphological differences in the symphyseal region between average grower Class I, Class II, and Class III skeletal malocclusions except mandibular incisor dentoalveolar height (L1-AH) and incisor mandibular plane angle which is higher whereas ramus length and body length which is lesser in Class II group as compared with controls. Width of the cervical region of the lower central incisor at the cementoenamel junction (Id-Id’) and incisor mandibular plane angle was lower than control in Class III subjects.

Craniofacial growth and SITAR growth curve analysis

BACKGROUND

SITAR (SuperImposition by Translation And Rotation) is a shape invariant growth curve model that effectively summarizes somatic growth in puberty.

AIM

To apply the SITAR model to longitudinal mandibular growth data to clarify its suitability to facial growth analysis.

SUBJECTS AND METHODS

2D-cephalometric data on two mandibular measurements (AP: articulare-pogonion; CP: condylion-pogonion) were selected from the Denver Growth Study, consisting of longitudinal records (age range: 7.9-19.0 years) of females (sample size N: 21; number of radiographs n: 154) and males (N: 18; n: 137). The SITAR mixed effects model estimated, for each measurement and gender separately, a mean growth curve versus chronological age, along with mean age at peak velocity (APV) and peak velocity (PV), plus subject-specific random effects for PV and mean size. The models were also fitted versus Greulich-Pyle bone age.

RESULTS

In males, mean APV occurred at 14.6 years (AP) and 14.4 years (CP), with mean PV 3.1 mm/year (AP) and 3.3 mm/year (CP). In females, APV occurred at 11.6 years (AP and CP), with mean PV 2.3 mm/year (AP) and 2.4 mm/year (CP). The models explained 95-96 per cent of the cross-sectional variance for males and 92-93 per cent for females. The random effects demonstrated standard deviations (SDs) in size of 5.6 mm for males and 3.9 mm for females, and SDs for PV between 0.3 and 0.5 mm/year. The bone age results were similar.

CONCLUSION

The SITAR model is a useful tool to analyse epidemiological craniofacial growth based on cephalometric data and provides an array of information on pubertal mandibular growth and its variance in a concise manner.

Estimating Craniofacial Growth Cessation: Comparison of Asymptote- and Rate-Based Methods

OBJECTIVE

To identify differences between asymptote- and rate-based methods for estimating age and size at growth cessation in linear craniofacial measurements.

DESIGN

This is a retrospective, longitudinal study. Five linear measurements were collected from lateral cephalograms as part of the Craniofacial Growth Consortium Study (CGCS). Four estimates of growth cessation, including 2 asymptote- (GC_asym, GC_err) and 2 rate-based (GC_abs, GC_10%) methods, from double logistic models of craniofacial growth were compared.

PARTICIPANTS

Cephalometric data from participants in 6 historic longitudinal growth studies were included in the CGCS. At least 1749 individuals (870 females, 879 males), unaffected by craniofacial anomalies, were included in all analyses. Individuals were represented by a median of 11 images between 2.5 and 31.3 years of age.

RESULTS

GC_asym consistently occurred before GC_err and GC_abs consistently occurred before GC_10% within the rate-based approaches. The ordering of the asymptote-based methods compared to the rate-based methods was not consistent across measurements or between males and females. Across the 5 measurements, age at growth cessation ranged from 13.56 (females, nasion-basion, GC_asym) to 24.39 (males, sella-gonion, GC_err).

CONCLUSIONS

Adolescent growth cessation is an important milestone for treatment planning. Based on our findings, we recommend careful consideration of specific definitions of growth cessation in both clinical and research settings since the most appropriate estimation method may differ according to patients' needs. The different methods presented here provide useful estimates of growth cessation that can be applied to raw data and to a variety of statistical models of craniofacial growth.

Craniofacial growth predictors for class II and III malocclusions: A systematic review

Objective

To evaluate the validity of craniofacial growth predictors in class II and III malocclusion.

Material and methods

An electronic search was conducted until August 2020 in PubMed, Cochrane Library, Embase, EBSCOhost, ScienceDirect, Scopus, Bireme, Lilacs and Scielo including all languages. The articles were selected and analyzed by two authors independently and the selected studies was assessed using the 14‐item Quality Assessment Tool for Diagnostic Accuracy Studies (QUADAS‐2). The quality of evidence and strength of recommendation was assessed by the GRADE tool.

Results

In a selection process of two phases, 10 articles were included. The studies were grouped according to malocclusion growth predictor in (1) class II (n = 4); (2) class III (n = 5) and (3) class II and III (n = 1). The predictors were mainly based on data extracted from cephalometries and characterized by: equations, structural analysis, techniques and computer programs among others. The analyzed studies were methodologically heterogeneous and had low to moderate quality. For class II malocclusion, the predictors proposed in the studies with the best methodological quality were based on mathematical models and the Fishman system of maturation assessment. For class III malocclusion, the Fishman system could provide adequate growth prediction for short‐ and long‐term.

Conclusions

Because of the heterogeneity of the design, methodology and the quality of the articles reviewed, it is not possible to establish only a growth prediction system for class II and III malocclusion. High‐quality cohort studies are needed, well defined data extraction from cephalometries, radiographies and clinical characteristics are required to design a reliable predictor.

Geometric morphometric analysis of craniofacial growth between the ages of 12 and 14 in normal humans

Aim

There is great variation of growth among individuals. The question whether patients with different skeletal discrepancies grow differently is biologically interesting but also important in designing clinical trials. The aim of the present study was to evaluate whether growth direction depends on the initial craniofacial pattern.

Subjects and method

The sample consisted of 350 lateral cephalograms of 175 subjects (91 females and 84 males) followed during normal growth without any orthodontic treatment. The examined ages were 12 (T1) and 14 (T2) years. The cephalograms were obtained from the American Association of Orthodontists Foundation (AAOF) Craniofacial Growth Legacy Collection (Burlington, Fels, Iowa, and Oregon growth studies). We digitally traced 15 curves on each cephalogram, comprehensively covering the craniofacial skeleton, and located 127 points on the curves, 117 of which were sliding semilandmarks and 10 fixed. Procrustes alignment, principal component analysis and two-block partial least squares analysis were performed, after sliding the semilandmarks to minimize bending energy.

Results

The first 10 principal components (PCs) described approximately 71 per cent of the total shape variance. PC1 was related to shape variance in the vertical direction (low/high angle skeletal pattern) and PC2 was mainly related to shape variance in the anteroposterior direction (Class II/Class III pattern). PC3 was mainly related to the shape variance of the mandibular angle. All subjects shared a similar growth trajectory in shape space. We did not find any correlation between the initial shape and the magnitude of shape change between T1 and T2, but males showed a greater shape change than females. The direction of shape change was moderately correlated to the initial shape (RV coefficient: 0.14, P < 0.001).

Conclusions

The initial shape of the craniofacial complex covaried weakly with the direction of shape change during growth.

Craniofacial growth studies in orthodontic research — lessons, considerations and controversies

The distinguishing features of Class I, Class II and Class III craniofacial growth have been subjects of orthodontic research since the middle of the 20th century. However, the moral and practical issues related to studying craniofacial growth in modern times have presented unresolved challenges to researchers. While previous longitudinal growth investigations are typically based on historical data sets, the cephalometric growth studies of contemporary populations must now rely on cross-sectional data. Furthermore, clinical orthodontic research has faced similar ethical challenges in which therapeutic outcomes are analysed using historical control data. These limitations, amongst others, have obscured the conclusions that can be drawn from both types of studies. This article begins with a review of the defining characteristics of Class I, Class II and Class III growth and then explores the limitations of growth studies and the use of historical control groups in orthodontic research.

Effect of functional appliances on the airway dimensions in patients with skeletal class II malocclusion: A systematic review

OBJECTIVES

The aim of the present systematic review was to assess the effect of functional appliances on the airway dimensions in patients with skeletal Class II malocclusion.

MATERIALS AND METHODS

Articles were identified through a literature survey carried out through the following databases: (1) PUBMED, (2) Google Scholar, (3) The Cochrane Library, (4) Embase, (5) Lilac, and (6) Web of Scholars. The systematic review analyzed 12 articles comprising removable functional appliances, 3 articles with fixed functional appliances, and 2 articles having both fixed and removable functional appliances.

RESULTS

Qualitative assessment was done for all the 17 studies. The effect of functional appliances in the dimensions of three airway spaces - nasopharynx, oropharynx, and hypopharynx were analyzed.

CONCLUSIONS

Significant increase in the dimensions of nasopharynx and oropharynx was observed with Activator. Significant increase in the nasopharynx and hypopharynx (male patients) was observed with Bionator. Insignificant increase in the oropharynx was observed with the same. Significant increase in the oropharynx and hypopharynx was observed with Twin Block. Insignificant increase in the nasopharynx was observed with the same. Significant increase was observed only in the hypopharynx for Frankel II. Decreased or insignificant change was observed with FMA, MPA IV, and Herbst appliances.

Selecting subjects with high craniofacial shape homogeneity for clinical trials

INTRODUCTION

Morphologic homogeneity is desirable in sample selection of clinical studies that evaluate methods of treating craniofacial discrepancies in orthodontics. The purposes of this study were to assess sample selection criteria commonly used in the orthodontic literature regarding their effectiveness in achieving morphologic homogeneity, and to propose a method that can guarantee selection of a homogeneous sample, for which the degree of homogeneity and the average skeletal pattern can be specified a priori.

METHODS

Pretreatment lateral cephalograms from 170 consecutive patients (82 boys, 88 girls) aged 7 to 17 years were used. Sixteen skeletal and 4 dental landmarks were digitized and processed with Procrustes superimposition and principal component analysis. The sample was bootstrapped to a virtual population of 10,000 subjects by random sampling from the normal distribution for each principal component. A systematic literature search of randomized controlled trials showed that the most prevalent sample selection criteria, in addition to molar relationship, included overjet, ANB, and SN-GoGn. Each criterion was applied to the virtual population. The morphologic homogeneity of the samples was assessed as the percentage of shape variance of each sample relative to the shape variance of the population.

RESULTS

The first 3 principal components incorporated approximately 53% of shape variability. The evaluated criteria achieved low or moderate morphologic homogeneity scores (range, 28%-63%), and the selected patients were widely spread in the shape space. Although the criteria are commonly applied for selecting samples with skeletal discrepancies, a considerable number of subjects with an average shape were selected. The proposed procedure entails selecting a skeletal pattern appropriate for the study's purpose, setting limits in shape space within which the sample should be confined, and testing candidate patients against these limits. The patients within these boundaries have, by definition, a similar shape to the selected skeletal pattern and form a homogeneous sample.

CONCLUSIONS

The cephalometric variables that have been used in randomized controlled trials do not result in samples of high morphologic homogeneity. The proposed method guarantees high morphologic homogeneity. The extent of homogeneity, the average shape of the sample, and the sample's relationship to the general population's average can be specified a priori.

Variation in timing, duration, intensity, and direction of adolescent growth in the mandible, maxilla, and cranial base: the Fels longitudinal study

There is considerable individual variation in the timing, duration, and intensity of growth that occurs in the craniofacial complex during childhood and adolescence. The purpose of this article is to describe the extent of this variation between traits and between individuals within the Fels Longitudinal Study (FLS). Polynomial multilevel models were used to estimate the ages of onset, peak velocity, and cessation of adolescent growth, the time between these ages, the amount of growth between these ages, and peak velocity. This was done at both the group and individual levels for standard cephalometric measurements of the lengths of the mandible, maxilla, and cranial base, the gonial angle, and the saddle angle. Data are from 293 untreated boys and girls age 4-24 years in the FLS. The timing of the adolescent growth spurt was, in general, not significantly different between the mandible and the maxilla, with each having an earlier age of onset, later age of peak velocity, and later age of cessation of growth as compared to the cranial base length. Compared to lengths, angles had in general later ages of onset, peak velocity, and cessation of growth. Accurate characterization of the ontogenetic trajectories of the traits in the craniofacial complex is critical for both clinicians seeking to optimize treatment timing and anatomists interested in examining heterochrony.

Longitudinal study of mandibular behavior in Class I subjects with vertical and horizontal growth

OBJECTIVE: To evaluate possible differences in mandibular behavior in Class I individuals with vertical and horizontal growth patterns. METHODS: The sample consisted of 20 untreated Class I individuals divided into: Group 1 comprising 10 individuals with vertical growth pattern and Group 2 comprising 10 individuals with horizontal growth pattern, all of them belonging to the Burlington Growth Center files, University of Toronto-Canada, radiographically followed-up at ages 9, 12 and 21. Cephalometric radiographs, determined mean values for a long-term evaluation of mandibular behavior using the following measurements: SNB, Co-GN, SN.GoMe, anterior facial height and posterior facial height. RESULTS: SNB and Co-Gn values were higher in horizontal growth group at all of the ages studied; SN.GoMe measure was significantly lower in horizontal growth group; anterior facial height (AFH) showed lower values in individuals with horizontal growth pattern; and posterior facial height (PFH) showed lower values in individuals with vertical growth pattern. CONCLUSION: Long-term comparisons of Class I individuals' growth tendencies indicate that there are significant differences between both groups. Mandible showed a trend to clockwise rotation in Group 1. Group 2 showed a trend to brachycephalic facial form, due to the deficit in vertical development with regard to anterior facial height.

Cephalometric characterization of skeletal Class II, division 1 malocclusion in white Brazilian subjects

One of the main points in Orthodontic studies is the growth and development of the craniofacial structures. In this study, skeletal cephalometric characteristics of Class II, division 1 malocclusion were assessed in lateral cephalograms. The experimental sample comprised 55 white Brazilian individuals of both genders, with an ANB angle of 4.5 degrees or higher. The mean age of the subjects was 13.5 years. Steiner and McNamara Jr cephalometric analyses were used in order to evaluate the relation between angular and linear positions of the apical bases, the dental and cranial structures, comparing with the values obtained in the control group (available at Bauru Dental School-USP). The results showed that, for the experimental group, the maxilla was well positioned in relation to the cranial base. The maxillomandibular relation showed an increased overjet, which was predictable based on criteria for sample selection. The geometrical proportion of the apical bases presented a small mandible and a normal sized maxilla. The craniofacial growth pattern presented a vertical tendency. The maxillary incisors were buccally inclined and well positioned by the linear evaluation. The mandibular incisors showed marked buccal inclination and protrusion. No statistically significant difference between genders was found.

Evaluation of mandibular morphology in different facial types

The purpose of this study was to evaluate mandibular morphology in different facial types using various parameters. This study was conducted on lateral cephalograms of a total of 110 subjects, which included 55 males and 55 females between the age of 18-25 years having a mean of 22.3 years for males and 21.5 years for females. The sample was divided into normodivergent, hypodivergent, and hyperdivergent subgroups based on Jarabak's ratio. Symphysis height, depth, ratio (height/depth) and angle, antegonial notch depth, ramal height and width, mandibular depth, upper, lower, and total gonial angle, and mandibular arc angle were analyzed statistically and graphically. It was found that the mandible with the vertical growth pattern was associated with a symphysis with large height, small depth, large ratio, small angle, decreased ramus height and width, smaller mandibular depth, increased gonial angle, and decreased mandibular arc angle in contrast to mandible with a horizontal growth pattern. Sexual dichotomy was found with mean symphysis height and depth in the female sample being smaller than in the male sample, but symphysis ratio was larger in the female sample; males having greater ramus height and width, mandibular depth than females. The mandible seemed to have retained its infantile characteristics with all its processes underdeveloped in hyperdivergent group.

Ethnic differences in the soft tissue profiles of Turkish and European-American young adults with normal occlusions and well-balanced faces

The aim of this study was to evaluate soft tissue differences between Turkish and North American adults by comparing two sample populations with ideal occlusion and well-balanced faces. Lateral cephalometric radiographs of 117 Anatolian Turkish adults (65 female and 52 male, mean age: 23.9 ± 2.8 years) were compared with a sample of 116 adults of European-American ancestry (64 female and 52 male, mean age: 25.0 ± 6.8 years). The cephalometric analyses of Holdaway, Epker, and Legan and Burstone were performed using Dolphin Image Software 9.0. Thirty-two measurements (27 linear and 5 angular) were analysed. For statistical evaluation, independent samples t-tests were performed. Distinct differences were found between the two samples in facial convexity, upper lip position and length, lower lip position, chin prominence, and chin thickness. Vertical proportional findings were similar between groups. Ethnic differences were found between Turkish and North American adults in the soft tissue profile. It is appropriate to consider these differences during routine diagnosis and treatment planning of a Turkish patient or an American patient of European ancestry.

Age-dependant cephalometric standards as determined by multilevel modeling

INTRODUCTION

The purpose of this study was to evaluate the feasibility of constructing age-dependant cephalometric standards for white subjects by using 3 data sets.

METHODS

The data sets were the samples from the Fels Longitudinal Study (United States), the Michigan Growth Study (United States), and the Nijmegen Growth Study (The Netherlands). The 3 mixed-longitudinal samples provided data for 218 girls and 231 boys between 9 and 14 years of age and were compared based on 4 cephalometric angles: SNA, SNB, ANB, and SN/GoMe. Curve-fitting and statistical comparisons were performed with multilevel modeling procedures.

RESULTS

All 4 angles showed linear changes over time. SNA and SNB increased, whereas ANB and SN/GoMe decreased. Based on paired-sample comparisons, the samples displayed statistically significant (P <0.05) differences for 50% of the growth velocities and 8% to 17% of the intercepts (size of the angle at 11 years). The SNA and SNB angles showed small and inconsistent differences across the samples. The ANB angle for the Fels boys decreased less than in the other 2 samples. The Nijmegen and Fels girls had the greatest and the least decreases, respectively, in the SN/GoMe angle. Most sample differences decreased over time.

CONCLUSIONS

Based on the growth differences identified, we concluded that sagittal and vertical jaw relationships have different patterns of growth in different samples of white subjects; indiscriminate pooling of data, to create age-dependant cephalometric standards for white subjects is not recommended.

Thin-plate Spline Analysis of Craniofacial Growth in Class I and Class II Subjects

Objective: To compare the craniofacial growth characteristics of untreated subjects with Class II division 1 malocclusion with those of subjects with normal (Class I) occlusion from the prepubertal through the postpubertal stages of development.

Materials and Methods: The Class II division 1 sample consisted of 17 subjects (11 boys and six girls). The Class I sample also consisted of 17 subjects (13 boys and four girls). Three craniofacial regions (cranial base, maxilla, and mandible) were analyzed on the lateral cephalograms of the subjects in both groups by means of thin-plate spline analysis at T1 (prepubertal) and T2 (postpubertal). Both cross-sectional and longitudinal comparisons were performed on both size and shape differences between the two groups.

Results: The results showed an increased cranial base angulation as a morphological feature of Class II malocclusion at the prepubertal developmental phase. Maxillary changes in either shape or size were not significant. Subjects with Class II malocclusion exhibited a significant deficiency in the size of the mandible at the completion of active craniofacial growth as compared with Class I subjects.

Conclusion: A significant deficiency in the size of the mandible became apparent in Class II subjects during the circumpubertal period and it was still present at the completion of active craniofacial growth.

Treatment stability with the eruption guidance appliance

INTRODUCTION

Although the eruption guidance appliance has been used to correct Class II malocclusions for many years and its effects have been demonstrated, there is no study on the stability of the changes it produces. Therefore, the objective of this study was to investigate the long-term stability of cephalometric dentoskeletal and occlusal changes after eruption guidance appliance therapy.

METHODS

Thirty-nine patients were evaluated. Occlusal evaluations were made with the peer asseessment rating index, and anterior tooth irregularity was evaluated with the Little irregularity index. Cephalometric and occlusal data were obtained at pretreatment, posttreatment, and postretention. The data were analyzed by dependent 1-way analysis of variance (ANOVA) for comparison between the 3 stages of the experimental group, with the Newman-Keuls test as a second step. To compare the cephalometric experimental group changes with mean population changes, the t test was used.

RESULTS

Cephalometrically, in the postretention stage, overjet remained stable, overbite showed significant relapse, and molar relationship improved toward a Class I relationship. The peer asseessment rating index showed stability of the occlusion. The Little irregularity index demonstrated a statistically significant relapse of crowding in the postretention stage.

CONCLUSIONS

Cephalometrically, overjet and molar relationship were stable in the long term after treatment with the eruption guidance appliance; however, there was relapse of the overbite. Occlusally, correction of the malocclusion elevated by the peer assessment rating was stable. There was relapse of the anterior teeth crowding.

Skeletal and Dental Changes in Class II division 1 Malocclusions Treated with Splint-Type Herbst Appliances

OBJECTIVE

To evaluate skeletal and dental changes in growing individuals through lateral cephalograms obtained after the sole use of the splint-type Herbst appliances in Class II division 1 malocclusions.

METHODS

Several electronic databases (Pubmed, Medline, Medline In-Process & Other Non-Indexed Citations, Cochrane Library Database, Embase, Web of Sciences, Scopus, and Lilacs) were searched with the help of a health sciences librarian. Abstracts that appeared to fulfill the initial selection criteria were selected by consensus. The original articles were then retrieved. Their references were also hand-searched for possible missing articles. Clinical trials that assessed, through lateral cephalograms, immediate skeletal and dental changes with the use of splint-type Herbst appliances without any concurrent orthodontic appliances, surgical intervention, or syndromic characteristics were considered. A comparable untreated Class II division 1 malocclusion control group was required to factor out normal growth changes.

RESULTS

Three articles were finally selected and analyzed. An individual analysis of these articles was made and some methodological flaws were identified. The selected studies all showed statistically significant changes in the anteroposterior length of the mandible, vertical height of the ramus, lower facial height, mandibular incisor proclination, mesial movement of the lower molars, and distal movement of the upper molars. Posttreatment relapse in overjet and molar relationship was also observed.

CONCLUSIONS

Dental changes are as important as skeletal changes to attaining the final occlusal results. Long-term, prospective, double-blinded, randomized clinical trials are needed to support these conclusions.

Mandibular changes produced by functional appliances in Class II malocclusion: A systematic review

The aim of this systematic review of the literature was to assess the scientific evidence on the efficiency of functional appliances in enhancing mandibular growth in Class II subjects. A literature survey was performed by applying the Medline database (Entrez PubMed). The survey covered the period from January 1966 to January 2005 and used the medical subject headings (MeSH). The following study types that reported data on treatment effects were included: randomized clinical trials (RCTs), and prospective and retrospective longitudinal controlled clinical trials (CCTs) with untreated Class II controls. The search strategy resulted in 704 articles. After selection according to the inclusion/exclusion criteria, 22 articles qualified for the final analysis. Four RCTs and 18 CCTs were retrieved. The quality standards of these investigations ranged from low (3 studies) to medium/high (6 studies). Two-thirds of the samples in the 22 studies reported a clinically significant supplementary elongation in total mandibular length (a change greater than 2.0 mm in the treated group compared with the untreated group) as a result of overall active treatment with functional appliances. The amount of supplementary mandibular growth appears to be significantly larger if the functional treatment is performed at the pubertal peak in skeletal maturation. None of the 4 RCTs reported a clinically significant change in mandibular length induced by functional appliances; 3 of the 4 RCTs treated subjects at a prepubertal stage of skeletal maturity. The Herbst appliance showed the highest coefficient of efficiency (0.28 mm per month) followed by the Twin-block (0.23 mm per month).

Age-related changes in sagittal relationship between the maxilla and mandible

The aim of the study was to assess age-related changes in sagittal jaw relationship during pre-pubertal and pubertal development on the basis of angular [ANB, anteroposterior dysplasia indicator (APDI) and A-B plane angle] and linear (Wits, AF-BF, App-Bpp, and App-Pgpp) measurements. Lateral cephalograms of orthodontically untreated subjects were evaluated at 7, 9, 11, 13 and 15 years of age. Cephalometric standards and age-related changes were determined on the basis of Class I subjects with a good occlusion (n = 18, 10 males and 8 females). With respect to changes related to growth, the main findings were, in both genders, a statistically significant age-related decrease in ANB angle, App-Bpp and App-Pgpp, a significant increase in APDI, but no age-related change in Wits. A reduction of sagittal jaw distance during pre-pubertal and pubertal development was observed arising from a relative dominance of sagittal mandibular growth. For an evaluation of differences concerning jaw relationship in Class II subjects, a group with Class II division 1 malocclusions (n = 17) and a group with Class II division 2 malocclusions (n = 12 were compared with two control groups, i.e. the good occlusion group and a Class I group (n = 37). Conclusions about the sagittal discrepancy in Class II division 1 and Class II division 2 subjects depended on the geometric reference used in the various parameters, and further research is called for with respect to the diagnostic performance of the various measurements. Differences between Class II subjects and controls present at 15 years of age were already established at 7 years of age, but were less pronounced.

A longitudinal 3-dimensional size and shape comparison of untreated Class I and Class II subjects

BACKGROUND

The invention of the Broadbent-Bolton cephalometer in 1925 made possible the collection of 3-dimensional data from biorthogonal plain film head radiographs. The objective of this study was to compare longitudinal changes in the shape and size of craniofacial structures between 16 untreated Class II Division 1 girls and 16 untreated Class I Bolton girls.

METHODS

Procrustes analyses were used to compare differences in 30 cephalometric landmarks that were 3-dimensional. The same methods were also used to analyze changes of 4 subsets of landmarks (maxilla, mandible, midface, and cranial vault). Comparisons included shape and size differences between adjacent age groups at ages 6, 11, and 15 in the Class II sample as well as between the Class I and Class II samples at each age.

RESULTS

Overall, the craniofacial complex underwent continuous shape change from ages 6 to 15 in both samples. In the Class II sample, the smallest contribution to craniofacial shape change was seen for the mandibular landmarks between ages 6 and 11. Compared with the Class I sample, the Class II sample had (1) a longer facial pattern, (2) the smallest mandibular shape difference at age 6 and the largest at age 15, and (3) more protrusive maxillary landmarks at all ages compared with the Class I sample. The Class II sample also had the largest change in size from ages 11 to 15 (6.5%), whereas the Class I sample showed the greatest size change (10.5%) from ages 6 to 11.

CONCLUSIONS

Clinically significant size and shape differences were observed during growth and development between Class II and Class I subjects in this sample.

Craniofacial analysis of the Tweed Foundation in Angle Class II, division 1 malocclusion

This study has defined the cephalometric values of the Craniofacial Analysis of the Tweed Foundation for a sample of Brazilian subjects. The sample consisted of 211 cephalometric radiographs from subjects aged 12-15, which were divided into two groups: Class II group, with 168 lateral teleradiographs (cephalograms) of white Brazilian subjects, with Angle Class II, division 1 malocclusion, of both genders (82 males and 86 females); and the Control Group, with 43 lateral teleradiographs (cephalograms) of subjects whose occlusion was clinically excellent, and also of both genders (21 males and 22 females). The teleradiographs were selected from the files of the Department of Orthodontics, School of Dentistry of Piracicaba, State University of Campinas, previously to the orthodontic treatment. The results demonstrated no sexual dimorphism for each group, as attested by the Student's t-test. The exploratory analysis (± 0.5 standard deviation) enabled the tolerance limits to be determined and a Craniofacial Analysis Table to be constructed using the respective cephalometric intervals. In addition, the difference between the two groups was not statistically significant according to the maxilla position. The maxilla was in a good position in relation to the cranial base. On the other hand, the mandible was retruded in relation to the cranial base in the Class II cases. The skeletal pattern was not defined because only the Facial Height Index (FHI) showed a vertical pattern in Class II subjects, while the Y Axis, SN.PlO, SN.GoMe and FMA values did not show any statistically significant difference between the groups. The Class II division 1 subjects showed lower incisors more labially tipped and a convex facial profile.

Variation in Class II malocclusion: comparison of Mexican mestizos and American whites

This study compared the skeletal and dental characteristics of Class II Division 1 white Americans and Mexicans. It was designed specifically to the evaluate ethnic, age, and sex differences of 101 whites and 107 Mexican mestizos, with approximately equal numbers in each subgroup. Three-way analyses of variance were used to simultaneously evaluate the effects of age, sex, ethnicity, and their interactions. Although Mexicans and whites in the United States had similar maxillomandibular relationships, Mexicans showed greater protrusion of the jaws and teeth. Mexican subjects with Class II malocclusions also showed less divergence of the cranial base (SN-FH angle) and greater vertical tendencies (MPA, Y-axis, and palatal plane angle) than their white counterparts. In comparison with children (mean age 9.0 years), young adults (mean age 20.1 years) had significantly larger craniofacial dimensions, jaws that were positioned more forward, and teeth that were more protruded. Sex differences pertained only to size (men were larger) and maxillary incisor angulation (men were more protrusive). The findings pertaining to the ethnic differences have important clinical implications regarding treatment decisions for Mexican and white patients. In addition, this study provides a foundation for future studies pertaining to Class II malocclusion in Mexicans.

A comparison of craniofacial Class I and Class II growth patterns

Longitudinal craniofacial databases, including the Fels Longitudinal Study, the Michigan Growth Study, and the Nijmegen (The Netherlands) Growth Study, were compared for a set of 12 craniofacial measurements on lateral skull cephalograms. The age ranges of the subjects were 7-14 years for females and 9-14 years for males. When we compared the normally distributed databases using multiple comparisons, a small sample test statistic t for differences between means of the databases showed few statistical differences. The databases were therefore pooled, and sex-specific Class I (ANB < 4 degrees), and Class II (ANB > or = 4 degrees) subsamples were analyzed with the same t test. The sizes of these subsamples ranged from 39 to 122 at the different ages. The findings showed that the Class II samples had greater SNA and SN-GoMe angles. Compared with the Class I group, shorter mandibles were found in the younger age groups of the Class II samples. No differences were found in mandibular length (Ar-Gn) and mandibular body length (Go-Gn) in the older Class II groups compared with the Class I groups. These findings indicate that the greater mandibular lengthening in the Class II groups might have contributed to successful Class II treatment in studies in which a Class I group was the control. Because of individual biological variability, the average Class I or Class II growth pattern might not be a realistic assumption or have clinical relevance for individual patients.

Midsagittal facial soft-tissue growth of French Canadian adolescents

This study examines changes in 12 midline soft-tissue thicknesses from the forehead, nose, lip, and chin regions in girls and boys from 10 to 16 years of age. The soft-tissue changes are compared to changes in two hard-tissue distances (sella-nasion and nasion-menton). The subjects are from a mixed-longitudinal sample studied at the Montreal Human Growth Research Center in the 1960s and 1970s. Total sample size is 242 (from lateral cephalographs of 124 males and 118 females), with numbers varying by age and measurement. For hard-tissues, boys show clearly defined adolescent spurts, while girls display small velocity increases indicative of only very minor spurts. Forehead tissue thicknesses for both sexes change little and show no demonstrable growth spurts. For the nose and philtrum region, which have the greatest absolute soft-tissue growth changes, both boys and girls show adolescent spurts. Peak velocities are attained between 13 and 14 years in boys and between 11.9 and 12.5 years in girls. Boys appear to have small adolescent spurts for upper (13.7 years) and perhaps lower lip thicknesses. Neither sex displays clear evidence for adolescent spurts in the chin region.

Dental and facial skeletal characteristics and growth of females and males with Class II Division 1 malocclusion between the ages of 10 and 14 (revisited). Part II. Anteroposterior and vertical circumpubertal growth

Growth changes in the dentition and the facial skeleton of boys and girls with Class I malocclusion from 10 to 14 years of age are presented, and the changes are compared with those for children with Class II Division 1 malocclusion. Radiographs of 335 children with Class II Division 1 malocclusion and 273 Class I controls were assessed. Radiographs were converted to x and y coordinate data, and 52 commonly used linear, angular, and coordinate axis measurements were made. Both the Class II Division 1 and the control groups were subdivided into 6 samples according to sex and skeletal age (10, 12, and 14 years +/- 6 months; chronological age ranged from 8.5 to 15.5 years). The mean plots from the coordinate data for the Class I boys and girls at 14 years were superimposed over the mean plots for the 10-year-old groups, creating circumpubertal growth standards. The standards are supported by growth vector diagrams and other data and lead to the following conclusions: (1) boys and girls with Class I malocclusion differ distinctly from each other in the amount and the direction of circumpubertal growth; (2) radiographic composite standards are useful and accurate clinical tools to show mean dentofacial skeletal growth and change between 10 and 14 years of age; (3) compared with the controls, the maxillary dentition of girls with Class II Division 1 malocclusion grows more horizontally, the maxillary (but not the mandibular) incisors procline farther, and the mandible grows more horizontally; (4) compared with the controls, the midfacial convexity in Class II Division 1 boys is markedly increased, due to more horizontal growth at A-point and less horizontal growth at nasion and pogonion, and maxillary and mandibular anterior teeth are proclined farther; (5) angular measurements involving S, N, A-point, B-point, and Pog are useful only when the position of N is known; and (6) cranial base flexure bears no relationship to the development of Class II Division 1 malocclusion.

Postsurgical growth changes in the mandible of adolescents with vertical maxillary excess growth pattern

This case-control study investigates the effects of superior maxillary repositioning by LeFort I osteotomy on adolescent mandibular growth. A total of 15 growing patients (average age, 12.8 years) with vertical maxillary excess who had undergone maxillary surgery were compared with matched untreated control subjects. Lateral cephalograms were evaluated and superimposed to describe the presurgical (1.6 years), surgical, and postsurgical (4.0 years) changes. During the presurgical period, comparisons of traditional measures and mandibular modeling changes showed no significant differences between the 2 groups. During surgery, the maxilla was impacted approximately 3 mm anteriorly and 1 mm posteriorly, which caused a 3.2 degrees autorotation of the mandible. During the postsurgical period, there was no change in the vertical growth pattern of the surgical patients, with the vertical facial heights increasing the same as the control subjects and the mandible rotating backwards. Although there was no inhibition of mandibular growth in the patients postsurgically, there was a decrease in horizontal maxillary growth compared with control subjects. There were clear postsurgical changes in the mandibular modeling and condylar growth, which were indicative of adaptive compensations for surgical mandibular repositioning and autorotation. It is concluded that early maxillary impaction does not normalize or inhibit the vertical maxillary excess growth pattern; mandibular modeling and condylar growth undergo adaptive changes in response to repositioning.

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.

Benefit of early Class II treatment: progress report of a two-phase randomized clinical trial

Preadolescent children with overjet greater than 7 mm were randomly assigned to observation only, headgear (combination), or functional appliance (modified bionator) and were monitored for 15 months. Of the 166 patients who completed this first phase of the trial, 147 continued to a second phase of treatment. The data from the first 107 patients to complete phase 2 are available and form the basis of this progress report. During phase 1, on average there was no change in the jaw relationship of untreated children, but 5% showed considerable improvement and 15% demonstrated worsening. Both early-treatment groups had a significant average reduction in ANB angle, more by change in maxillary dimensions in the headgear group and mandibular growth in the functional appliance group. There were wide variations in response, however, with only 75% of the treated children showing favorable skeletal response. Failure to respond favorably could not be explained by lack of cooperation alone. The preliminary results from phase 2 show that, on average, time in fixed appliances was shorter for children who underwent early treatment, but the total treatment time was considerably longer if the early phase of treatment was included. Only small differences were noted in anteroposterior jaw position between the groups at the completion of treatment, and the changes in dental occlusion, judged on the basis of Peer Assessment Rating scores, were similar between groups. Neither the severity of the initial problem nor the duration of treatment was correlated with the occlusal result. The number of patients who required extraction of permanent teeth was greater in the early functional appliance group than in the headgear or control group. The option of orthognathic surgery was presented more often in the cases of children who did not undergo early treatment, but surgery was accepted or was still being considered almost as frequently in the previous headgear group as in the controls, less often in the patients previously treated with functional appliances.

Orthognathic surgery effects on maxillary growth in patients with vertical maxillary excess

This study assesses the effects of superior repositioning of the maxilla by LeFort I osteotomy on adolescent maxillary growth. A total of 48 patients, 23 who were stabilized with rigid fixation (RF) and 25 stabilized with wire fixation (WF), were compared with closely matched unoperated controls. Comparisons were made for the presurgical intervals (2.3 years for RF and 1.3 years for WF groups) and postsurgical intervals (1.9 years for RF and 2.3 years for the WF groups). Lateral cephalograms were evaluated to describe the presurgical and postsurgical spatial changes of the maxilla. During the presurgical interval, there were no significant differences in vertical or horizontal maxillary growth between the WF group and their controls. Although vertical growth changes were similar, the RF group showed slightly more than expected posterior movement of the upper incisor during the presurgical interval. During surgery, the maxilla was advanced approximately 2 mm and impacted approximately 2 mm. After surgery, there were no statistically significant differences in vertical maxillary growth between the two surgical and control groups. Horizontally, the RF group showed maxillary stability, whereas the WF groups showed posterior movement. It is concluded that multiple piece LeFort I osteotomy has little or no effect on vertical maxillary growth; rigid fixation provides superior long-term anteroposterior stability compared with wire fixation.

Craniofacial structure of Japanese and European-American adults with normal occlusions and well-balanced faces

The purpose of this study is to compare two groups of adults from different races who were selected on the basis of having normal ("ideal") occlusions and well-balanced faces. The lateral cephalometric radiographs of 54 Japanese adults (26 men and 28 women) were compared with a sample of 125 adults (44 men and 81 women) of European-American ancestry. The samples were chosen by orthodontists of the same racial background as the sample selected. Each lateral cephalogram was traced and digitized, and differences between cephalometric measurements between groups were analyzed with completely randomized t tests. In comparison to the European-American sample, the Japanese sample, in general, was smaller in anteroposterior facial dimensions and proportionately larger in vertical facial dimensions. The facial axis angle was more vertical in Japanese subjects, indicating a more downward direction of facial development. On average, the subjects in the Japanese sample were more protrusive dentally, with a more acute nasolabial angle and a greater tendency toward bilabial protrusion. These differences, evident even in groups with so-called "well-balanced faces", indicate that fundamental variation exists in the craniofacial structure of Japanese and European-Americans. The results of this study support the premise that a single standard of facial esthetics is not appropriate for application to diverse racial and ethnic groups.

Male postpubertal facial growth in Class II malocclusions

Maxillary and mandibular postpubertal growth changes were assessed from lateral cephalograms taken when subjects were 16 and 20 years of age. The sample consisted of 39 male subjects with no previous orthodontic treatment who exhibited Class II skeletal characteristics. Significant increases in mean maxillary and mandibular measurements were observed over the age period studied. Mean mandibular growth (Co-Gn) was approximately three times that of maxillary growth (Co-A). Total mandibular growth observed between 16 to 20 years of age was approximately 4.3 mm. The mandible appeared to rotate anteriorly superiorly, reflected by a mean reduction in mandibular plane angle of 1.47 degrees and a greater increase in posterior versus anterior face height. There were not statistically significant changes in incisor angulation. Mean growth changes in this Class II sample were comparable to those previously reported for male subjects with Class I malocclusions over the same age period, suggesting a similarity in postpubertal development between these two groups.

Mandibular form and position in 10-year-old boys

It is unclear whether malocclusion characterized by jaw discrepancy is caused by variations in mandibular position, mandibular size, or a combination of the two. To clarify the situation, the mandibular outlines of 124 10-year-old boys, equally divided among the Angle classes, were generated from cephalograms with a computer plotting technique. The mean plots for each of the groups were superimposed on S-N and Go-Gn. These showed mandibular form and size to be similar in the Class I and Class III groups and in both divisions of Class II. The position of Class III mandibles was more anterior and rotated forward in relation to the cranial base compared with the other groups. Statistical analysis confirmed these findings. There was evidence to support the idea that Class II, Division 2 malocclusion is largely a dentoalveolar rather than a skeletal entity.

An inventory of United States and Canadian growth record sets: preliminary report

A listing and description of longitudinal craniofacial growth record sets currently extant on the North American continent is provided. An argument is made for the preservation of these resources and for the generation of a pooled or shared image base of duplicate craniofacial physical records. This is a preliminary report and is assumed to be incomplete. In an effort to improve our accuracy and completeness, we invite corrections and additions.

Changes in mandibular length before, during, and after successful orthopedic correction of Class II malocclusions, using a functional appliance

Forty-seven girls were successfully treated with a functional appliance (FA). To be included in this study, the rate of increase in mandibular length during treatment had to be greater than twice the mean rate for a subgroup of 20 of these patients evaluated during a pre-FA observation period. The mean mandibular growth rate was 6 mm per year while the FA was activated. In the ensuing months, cephalograms were taken at intervals coinciding with five post-FA phases, including complete edgewise treatment and retention. During the post-FA phase of initial edgewise treatment, the mandibular growth rate was dramatically reduced when compared with 47 controls matched for age, sex, and initial SN:GoGn angle. Selected individual cases are presented to illustrate the great variability in growth responses that were obtained. This study found highly significant increases in mandibular length still present 2 years after treatment, diminished but still significant gains after 3 years, and no significant difference after 4 years.

Facial growth in males 16 to 20 years of age

Postpubertal craniofacial skeletal and dental changes were examined from lateral cephalograms taken when subjects were 16, 18, and 20 years of age. The sample consisted of males with no previous orthodontic treatment who had Class I skeletal and dental characteristics. Mandibular growth was found to be statistically significant for the age periods of 16 to 18 years and 18 to 20 years. Growth from 16 to 18 years was greater than that from 18 to 20 years. Maxillary and mandibular growth were highly correlated at each age period. However, overall mandibular growth was approximately twice that of overall maxillary growth. Mandibular growth was found to involve an upward and forward rotation, a result of posterior vertical growth exceeding anterior vertical growth. Lower incisors were found to tip lingually with increasing age. Incremental changes in mandibular cephalometric measurements were found to be equivalent when measured from either articulare or condylion, indicating the interchangeability of the landmarks for growth estimates.

Modeling longitudinal mandibular growth: percentiles for gnathion from 6 to 15 years of age in girls

Growth of the cephalometric landmark gnathion is modeled mathematically with multilevel statistical techniques. The findings, pertaining to a mixed longitudinal sample (N = 772) of 105 girls, 6 to 15 years of age, provide the most accurate descriptions of longitudinal mandibular growth presently available. Polar, rather than rectangular, coordinates are used to better distinguish between the amount and direction of growth. The velocity curve for sella-gnathion includes growth spurts during childhood (7.5 years) and adolescence (12.7 years). Growth direction of gnathion changes regularly throughout the age range, indicating a relative increase of vertical over horizontal growth. These reference standards serve as a basis for comparing and better understanding abnormal growth patterns.

Pubertal growth of the cephalometric point gnathion: multilevel models for boys and girls

Two-level polynomial models are used to summarize the amount Sella-Gnathion (S-Gn) and direction Nasion-Sella-Gnathion (N-S-Gn) of growth changes for the cephalometric landmark gnathion. Growth descriptions pertain to a mixed longitudinal sample of 209 French-Canadian children 10-15 years of age. The boy's growth curve attains mean minimum prepubertal velocity at 10.8 years and maximum pubertal velocity at 14.1 years. The girl's curve follows a cubic pattern, attaining maximum pubertal velocity at 12.1 years. Boys are larger than girls throughout the age range. Variation between-subjects increases with age in a curvilinear fashion. Growth direction of gnathion is more horizontally directed for girls than boys. Small but significant changes in growth direction occur between 10 and 15 years of age.