Robert E. Moyers

Differential diagnosis of Class II malocclusions: Part 1. Facial types associated with Class II malocclusions

By means of computer-based statistical methods, several types of Class II malocclusion have been discovered with defining horizontal and vertical characteristics. Of the six horizontal types, four are severe syndromes, one is a loose, ill-defined grouping of cases with mild skeletal features, and one has only the dental features of Class II. Five vertical types associates with Class II were also revealed, although each vertical is not associated with all horizontal types. A simplified simulation of the computerized procedures has been developed for routine use in clinical practice.

Craniofacial adaptation to protrusive function in young rhesus monkeys

I t is still not fully understood how clinical corrections are achieved by activators and other related orthodontic and orthopedic procedures, largely because the role of function in craniofacial growth and orthodontic treatment is not yet clear. Numerous experiments have been conducted using different methods and producing widely varying results. Clinical studies have offered one avenue of approach to this problem. Patients treated by one of the functional jaw orthopedic methods have been analyzed individually or compared to untreated controls. Many of these studies reported differences in the craniofacial growth pattern, particularly in the mandible.lm4 Both Brownel and Marschner and Harris,2 in two of the few clinical studies that consider total mandibular length rather than mandibular positioning, noted significantly higher mandibular growth rates in the treated groups. However, Bj6rk5 stated that any skeletal changes during this type of treatment may well be within the range of normal growth. Other investigators5-7 found that treatment had no apparent effect on mandibular growth but, rather, acted by reshaping the alveolar arches, by altering vertical dimension, and by affecting the eruption and alignment of teeth. Definitive comparisons among these findings are somewhat obscured by differences in measuring methods, experimental design, and treatment procedures. Experimental approaches have also been taken. The studies most relevant to the clinician have been those utilizing nonhuman primates. Since the original

Some physiologic considerations of centric and other jaw relations

Abstract The postural position of the mandible is the only reflex determining mandibular position present at birth. Centric relation is learned after the teeth errupt: it is the first learned reflex determining the occlusal position of the mandible after the primary dentition is complete. Eccentric mandibular positions are learned as expedient mechanisms for avoiding occlusal disharmonies. They are forgotten when the source of the afferent impulses prompting them is removed. Centric relation in the edentulous adult is determined by muscle proprioceptors largely, and thus presents slightly different problems in registration.

Original articleDifferential diagnosis of Class II malocclusions: Part 1. Facial types associated with Class II malocclusions☆

By means of computer-based statistical methods, several types of Class II malocclusion have been discovered with defining horizontal and vertical characteristics. Of the six horizontal types, four are severe syndromes, one is a loose, ill-defined grouping of cases with mild skeletal features, and one has only the dental features of Class II. Five vertical types associates with Class II were also revealed, although each vertical is not associated with all horizontal types. A simplified simulation of the computerized procedures has been developed for routine use in clinical practice.

Prediction of craniofacial growth: The state of the art

M ost predictions of growth are based on some mathematical model of the growth process, two kinds of which can be distinguished: (1) the transformed coordinate method of D’Arcy Thompson,Z5 applied to human growth by MedawaPg and to craniofacial growth by Moorrees and Lebret,2z and (2) equations producing curves descriptive of processes--some intended to be of general application (for example, Gompertz’ equation, Weiss and Kavanaugh’P model, and the compound Gompertz-linear equation of LairdIE). Others were intended only for specific kinds of growth, such as Huxley’sle allometric equation and Tanner’sz4 equation. Useful though these equations may be for the analysis and description of growth, they have in common one unavoidable shortcoming so far as prediction is concerned: They do not adequately describe any single growth series. The orthodontist wishes to predict the future sizes and relationships of parts of a single person whose growth is usually abnormal and who may not be represented in any populations thus far studied. This article considers the state of the art in quantitative prediction of craniofacial measures of particular interest to orthodontists.

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.

Electromyography of the oral phase of deglutition in the Rhesus monkey (Macaca mulatta).

Summary-Patterns of activity of selected muscle groups which function during the oral phase of swallowing were analysed electromyographically in 33 monkeys (Macuca mulatta) during a total of 113 recording sessions. Salivary, water and masticatory swallows were studied. The activity of the suprahyoid muscle group was relatively constant in each animal during all types of swallows. However, three patterns of muscle activity of the other masticatory muscles were identified. In the first pattern (pattern A), the suprahyoids usually fired concurrently with the superior head of the lateral pterygoid muscle with little or no elevator activity evident. In the second pattern (pattern B), the temporal muscle, masseter muscle and superior head of the lateral pterygoid muscle fired concurrently with the suprahyoids. In the third pattern (pattern C), elevator and lateral pterygoid activity preceded the suprahyoid burst. The inferior head of the lateral pterygoid was not active in any swallowing pattern. About 60-70 per cent of the salivary swallows were of pattern A. Most water-swallows were of patterns B and C, while those swallows associated with mastication were entirely of pattern C.

An Electromyographic Analysis of the Temporalis Muscles and Certain Facial Muscles in Thumb-and Finger-sucking Patients

Every dentist is frequently confronted with the problem of digital sucking in children. Yet any information he can give questioning parents relies largely on opinions, observations, or argumentation, because very little scientific evidence is found in the literature. In 1958, Cook1 analyzed intraoral pressures involved during thumbor finger-sucking in a selected sample of 25 children. He found that there was a relationship between the type of pressure developed and the malocclusion observed. After such findings, one is naturally tempted to define more precisely the part played by the digital pressure and that played by the neuromuscular complex. Is the sucking habit a source of alteration in facial muscle function? If so, what muscles are mostly involved? The purpose of this study is to examine electromyographically the involvement of selected fifth and seventh cranial nerve muscles in a group of thumband finger-suckers.

A cephalometric template: Its construction and clinical significance

IN THE University of Michigan Orthodontic Clinic the growth pattern of each patient is considered to be an individual factor which must be studied wit,11 great carp. For this reason, patients are accepted in the clinic when they arcquite young, even though orthodontic treatment may not be initiated for somc~ time. Unfortunately, it is not always possible in practice to accumulate growth records on patients, and an immediate evaluation of present and potentia~l growth factors must be made. Est,imating the level of growth and development of a child at any givcll t imc is a matter of judgment. However, guide lines may be drawn t,o direct the clinician’s observations to critical relationships. To derive these guide lines, the I)cpartmcnt of Orthodontics has for many years c,ooperated with the Univcrsit!: of Michigan School of Education in a program known as the Universit.y 01 Michigan Wementary School Growth Study. One of the results of this project has been the compilation of a set of ccphalometric norms or standards. TIN transformation of tbesc data into a visual form or template suitable for t,ho rapid evaluation of lateral cephalograms by t,he clinician will be presented hcrc from a statist,&& biometric, and clinical viewpoint.

The stabilizing plate, an adjunct to orthodontic therapy

Abstract The stabilizing plate, an adjunct to orthodontic mechanical therapy, has been presented. A description of the device, methods of construction, and its clinical usage have been given.