Development of the mandibular curve of spee and maxillary compensating curve: A finite element model.

The curved planes of the human dentition seen in the sagittal view, the mandibular curve of Spee and the maxillary compensating curve, have clinical importance to modern dentistry and potential relevance to the craniofacial evolution of hominins. However, the mechanism providing the formation of these curved planes is poorly understood. To explore this further, we use a simplified finite element model, consisting of maxillary and mandibular "blocks", developed to simulate tooth eruption, and forces opposing eruption, during simplified masticatory function.

Characteristics of an excellent orthodontic residency program.

Introduction: Although unquantifiable features, such as faculty passion and dedication to teaching, play a vital role in defining the quality of residency education, determinable features that are fundamental to the definition of a "top tier" orthodontic residency program also exist. The objective of this study was to identify those features.

Methods: A survey with 32 items was developed and validated to assess the features of an excellent orthodontic program based on the following 3 major domains: faculty, education, and resident/graduate student/alumni.

Childhood body mass index is associated with early dental development and eruption in a longitudinal sample from the Iowa Facial Growth Study.

Introduction: Children with high body mass index (BMI) values have been demonstrated to have precocious dental development. Research has largely focused on cross-sectional data sets, leaving an incomplete understanding of the longitudinal relationship between BMI and dental maturation.

Methods: We used a pure longitudinal growth series to examine the relationship between dental development and childhood BMI.

Long-term skeletal effects of high-pull headgear followed by fixed appliances for the treatment of Class II malocclusions.

Objectives: The long-term skeletal effects of Class II treatment in growing individuals using high-pull facebow headgear and fixed edgewise appliances have not been reported. The purpose of this study was to evaluate the long-term skeletal effects of treatment using high-pull headgear followed by fixed orthodontic appliances compared to an untreated control group.

Materials And Methods: Changes in anteroposterior and vertical cephalometric measurements of 42 Class II subjects (n = 21, mean age = 10.

Candidate gene analyses of 3-dimensional dentoalveolar phenotypes in subjects with malocclusion.

Introduction: Genetic studies of malocclusion etiology have identified 4 deleterious mutations in genes DUSP6,ARHGAP21, FGF23, and ADAMTS1 in familial Class III cases. Although these variants may have large impacts on Class III phenotypic expression, their low frequency (<1%) makes them unlikely to explain most malocclusions. Thus, much of the genetic variation underlying the dentofacial phenotypic variation associated with malocclusion remains unknown.

Spatial determinants of the mandibular curve of Spee in modern and archaic Homo.

Objectives: The curve of Spee (COS) is a mesio-distally curved alignment of the canine through distal molar cusp tips in certain mammals including modern humans and some fossil hominins. In humans, the alignment varies from concave to flat, and previous studies have suggested that this difference reflects craniofacial morphology, including the degree of alveolar prognathism. However, the relationship between prognathism and concavity of the COS has not been tested in craniofacially variant populations.

Patterns of morphological integration in the dental arches of individuals with malocclusion.

Objectives: In humans, there is a large range of variation in the form of the maxillary and mandibular dental arches. This variation can manifest as either prognathism or retrognathism in either or both arches, which can cause malocclusion and lead to abnormal masticatory function. This study aims to identify aspects of variation and morphological integration existing in the dental arches of individuals with different types of malocclusion.

Nasal Septal Deviation and Facial Skeletal Asymmetries.

During ontogeny, the nasal septum exerts a morphogenetic influence on the surrounding facial skeleton. While the influence of the septum is well established in long snouted animal models, its role in human facial growth is less clear. If the septum is a facial growth center in humans, we would predict that deviated septal growth would be associated with facial skeletal asymmetries.

Match or non-Match: at the crossroads.

Introduction: The National Matching Service provides an ethical and unbiased selection process between residency programs and candidates. Currently, 51 of the 66 accredited orthodontic residency programs in the United States participate in the matching service for orthodontic programs (the Match), and 15 do not. Our purpose was to identify the factors that contribute to an orthodontic residency program's decision to participate in the Match program or to refrain from doing so.

Phenotypic diversity in white adults with moderate to severe Class II malocclusion.

Introduction: Class II malocclusion affects about 15% of the population in the United States and is characterized by a convex profile and occlusal disharmonies. The specific etiologic mechanisms resulting in the range of Class II dentoskeletal combinations observed are not yet understood. Most studies describing Class II phenotypic diversity have used moderate sample sizes or focused on younger patients who later in life might outgrow their Class II discrepancies; such a focus might also preclude the visualization of adult Class II features.

Ontogenetic scaling of the human nose in a longitudinal sample: implications for genus Homo facial evolution.

Researchers have hypothesized that nasal morphology, both in archaic Homo and in recent humans, is influenced by body mass and associated oxygen consumption demands required for tissue maintenance. Similarly, recent studies of the adult human nasal region have documented key differences in nasal form between males and females that are potentially linked to sexual dimorphism in body size, composition, and energetics. To better understand this potential developmental and functional dynamic, we first assessed sexual dimorphism in the nasal cavity in recent humans to determine when during ontogeny male-female differences in nasal cavity size appear.

Functional and morphological correlates of mandibular symphyseal form in a living human sample.

Variation in recent human mandibular form is often thought to reflect differences in masticatory behavior associated with variation in food preparation and subsistence strategies. Nevertheless, while mandibular variation in some human comparisons appear to reflect differences in functional loading, other comparisons indicate that this relationship is not universal. This suggests that morphological variation in the mandible is influenced by other factors that may obscure the effects of loading on mandibular form.

Phenotypic diversity in white adults with moderate to severe Class III malocclusion.

Introduction: Class III malocclusion is characterized by a composite of dentoskeletal patterns that lead to the forward positioning of the mandibular teeth in relation to the maxillary teeth and a concave profile. Environmental and genetic factors are associated with this condition, which affects 1% of the population in the United States and imposes significant esthetic and functional burdens on affected persons. The purpose of this study was to capture the phenotypic variation in a large sample of white adults with Class III malocclusion using multivariate reduction methods.

Effect of miniscrew placement torque on resistance to miniscrew movement under load.

Introduction: The primary stability of orthodontic anchorage miniscrews is believed to result from mechanical interlock, with success based upon a number of variables, including screw diameter, angle of placement, monocortical vs bicortical placement, placement through attached or unattached soft tissue, presence or absence of a pilot hole, periscrew inflammation, and maximum placement torque. The purpose of this ex-vivo study was to further explore the relationship between maximum placement torque during miniscrew placement and miniscrew resistance to movement under load.

Methods: Ninety-six titanium screws were placed into 24 hemi-maxillae and 24 hemi-mandibles from cadavers between the first and second premolars by using a digital torque screwdriver.

Cervical vertebrae maturation method morphologic criteria: poor reproducibility.

Introduction: The cervical vertebrae maturation (CVM) method has been advocated as a predictor of peak mandibular growth. A careful review of the literature showed potential methodologic errors that might influence the high reported reproducibility of the CVM method, and we recently established that the reproducibility of the CVM method was poor when these potential errors were eliminated. The purpose of this study was to further investigate the reproducibility of the individual vertebral patterns.

Chin development as a result of differential jaw growth.

Introduction: During facial growth, the maxilla and mandible translate downward and forward. Although the forward displacement of the maxilla is less than that of the mandible, the interarch relationship of the teeth in the sagittal view during growth remains essentially unchanged. Interdigitation is thought to provide a compensatory (tooth movement) mechanism for maintaining the pattern of occlusion during growth: the maxillary teeth move anteriorly relative to the maxilla while the mandibular teeth move posteriorly relative to the basilar mandible.

Effect of maxillary anteroposterior position on profile esthetics in headgear-treated patients.

Introduction: Headgears have been used to treat Class II malocclusions for over a century. The purpose of this retrospective study was to investigate the profile esthetic changes resulting from headgear use in growing Class II patients with protrusive, normal, and retrusive maxillae.

Methods: Profile silhouettes were created from pretreatment and posttreatment lateral cephalometric tracings of growing Class II patients treated with headgear followed by conventional fixed appliances.

Effect of miniscrew angulation on anchorage resistance.

Introduction: Even though the use of titanium miniscrews to provide orthodontic anchorage has become increasingly popular, there is no universally accepted screw-placement protocol. Variables include the presence or absence of a pilot hole, placement through attached or unattached soft tissue, and angle of placement. The purpose of this in-vitro study was to test the hypothesis that screw angulation affects screw-anchorage resistance.

Nasal septal and premaxillary developmental integration: implications for facial reduction in Homo.

The influence of the chondrocranium in craniofacial development and its role in the reduction of facial size and projection in the genus Homo is incompletely understood. As one component of the chondrocranium, the nasal septum has been argued to play a significant role in human midfacial growth, particularly with respect to its interaction with the premaxilla during prenatal and early postnatal development. Thus, understanding the precise role of nasal septal growth on the facial skeleton is potentially informative with respect to the evolutionary change in craniofacial form.

Mandibular "tripod" advancement of a Class II Division 2 deepbite malocclusion.

This case report describes the treatment of a 25-year-old woman with a Class II malocclusion, secondary to mandibular skeletal deficiency, and mild overclosure. Inferior surgical repositioning of the maxilla is often the treatment of choice for patients with maxillary vertical deficiency; however, this patient had borderline vertical deficiency that was treated with a mandibular "tripod" advancement (leveling of the mandibular arch after surgery) coupled with a setback and down-grafting genioplasty. The surgical-orthodontic treatment plan, combined with cosmetic dentistry, resulted in dramatically improved facial esthetics and occlusal relationships.

Sutural growth restriction and modern human facial evolution: an experimental study in a pig model.

Facial size reduction and facial retraction are key features that distinguish modern humans from archaic Homo. In order to more fully understand the emergence of modern human craniofacial form, it is necessary to understand the underlying evolutionary basis for these defining characteristics. Although it is well established that the cranial base exerts considerable influence on the evolutionary and ontogenetic development of facial form, less emphasis has been placed on developmental factors intrinsic to the facial skeleton proper.