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Biomedical subjects

J M Dibbets

Publications and source records attributed to J M Dibbets.

17 recordsLinked to original sources
PubMed1992

Long-term effects of orthodontic treatment, including extraction, on signs and symptoms attributed to CMD.

The prevalence of signs and symptoms attributed to craniomandibular disorders (CMD) was established in an orthodontically treated sample. The effect of orthodontic therapy upon this prevalence was studied by monitoring three groups of patients whose treatment procedures were different. The first group was treated with functional appliances, the second with Begg light wire, and the third with chin cups. In addition, the effect of extraction upon the prevalence was studied by monitoring three groups in which different extraction decisions had been made: four first premolars extracted, all other types of extraction, and no extraction. Based upon the finding of similar prevalences after 20 years of observation, it appears that neither orthodontic treatment nor extraction has a causal relationship with the signs and symptoms of CMD recorded during this study.

Activator Appliances↗
PubMed1992

Prevalence of structural bony change in the mandibular condyle.

Estimated on data derived from a longitudinal study of 172 orthodontic subjects, structural bony change in the mandibular condyle occurs in 5% of the individuals documented from childhood to adulthood. The first appearance generally was between 12 and 16 years of age. Differential diagnosis based upon signs and symptoms of CMD registered simultaneously, as proposed in the 1990 guidelines for craniomandibular disorders appeared to be inconsistent. To illustrate how suddenly the process of bony change may proceed, a case report is presented in which a severe change transpired within a 1-year interval in a 13-year-old patient.

Adolescent↗
PubMed1992

The prevalence of joint noises as related to age and gender.

The interdependence of joint noises on age and gender was studied mixed-longitudinally in orthodontically treated subjects from 7 to 38 years of age. The prevalence of clicking signs and symptoms increased up to 25 years of age and leveled thereafter. Around age 19, a significant gender difference was present in clicking symptoms, with females reporting more clicks. The same pattern, although not significantly, was present for palpated clicks. Since male and female clicking prevalences are the same before and after adolescence, and since girls mature at an earlier age than boys, it is concluded that these noises reflect a maturity level rather than a multifactorial disorder. The prevalence of crepitation continued to increase slowly.

Adolescent↗
PubMed1991

Extraction, orthodontic treatment, and craniomandibular dysfunction.

Signs and symptoms attributed to craniomandibular dysfunction (CMD) were registered in the Groningen longitudinal prospective study over a 15-year period. It is concluded that none of the three treatment types--removable appliances, Begg mechanics, and chin cups--should be considered causal factors for the signs and symptoms registered many years later. Furthermore, a comparison was made among nonextraction, extraction of all first premolars, and extraction of other teeth with regard to CMD and it was concluded that the original growth pattern that caused the teeth to be selected for extraction--rather than the extraction itself--is the most likely factor responsible for the frequency of CMD reported years later. This conclusion agrees with one based on a previously postulated idea about the relationship between dysfunction symptoms and growth patterns.

Adolescent↗
PubMed1991

Flattened condylar projection in children: reflection of seasonal growth?

'Deformed or flattened' X-ray projections of the mandibular condyle are incidentally reported in the literature. However, when studied longitudinally in a growing child, this characteristic appears to come and go in an unpredictable order. In addition, there is experimental evidence that in the rat elongated 'flattened' condyles can be cultured and that the rat condylar growth exhibits seasonal fluctuations. Therefore, the hypothesis was formulated that a part of the flattened condylar projections may reflect a temporarily active growth vector. The result of this study suggests that condylar flattened projections in children exhibit a seasonal variation and may possibly be interpreted as the reflection of a temporarily active growth vector.

Adolescent↗
PubMed1990

Mandibular rotation and enlargement.

In a previous article, a theoretical mechanism for neutralization of condylar incremental growth was postulated. It was labeled counterbalancing rotation. The postulate resulted from the reasoning that condylar relocation along a segment of a circle around pogonion would be unable to enlarge the radius. In this article, the relationship between condylar relocation and mandibular enlargement is quantified. To this goal, counterbalancing proportion is defined as the percentage of condylar incremental growth, detected by implants that has contributed to the enlargement of the condylion-to-pogonion dimension. This proportion proves to vary widely in the 21 cases documented by Björk and Skieller. In addition, a relationship between this proportion and the Angle classification is observed. It is concluded that counterbalancing rotation indeed must be considered a mechanism capable of neutralizing condylar incremental growth and may have clinical implications.

Cephalometry↗
PubMed1990

A method for structural mandibular superimpositioning.

Structural mandibular superimpositioning on stable natural references has gained wide acceptance in the orthodontic literature. However, accurate instructions that provide a simple step-by-step procedure are not readily available. Considering the specific method described here and assuming stability of the natural reference structures, a reliable procedure for marking two artificial references (simulating "implants") on mandibles in a longitudinal series of cephalograms appears to be possible. In essence, the method is based on the construction of a template, drawn on a small auxiliary tracing sheet, which contains only information relevant for structural mandibular superimpositioning plus error checks. This template is subsequently superimposed on the radiographs in a longitudinal series by the structural method, which permits the transference of two fiducial points. These fiducial points consequently replace the images of metallic implants and thus facilitate local superimpositioning of mandibles. It is a convenient method for longitudinal growth research as well as for any two successive records in the clinical situation.

Cephalometry↗
PubMed1990

The validity of experimental evidence.

Commonly the assumption is held that correct data only and always will lead to valid deductions. However, analysis of the literature reveals striking examples of erroneous conclusions based upon correct data. The present article intends to show that meticulously performed research in itself is no guarantee for correct conclusions. It appears that investigators, together with the "scientific forum" of their time, interpret the results of experiments in the light of accepted viewpoints, without challenging other or less likely explanations. And since this has happened to the best of us in the past, it is also apt to happen to us today.

Animals↗
PubMed1990

[Effects of acid etchants in orthodontics].

Direct bonding of brackets onto the tooth enamel has become a routine procedure in orthodontics. Some detrimental side effects of this technique are described. Most iatrogenic effects are restricted to the enamel and mostly when white spots exist before bonding the brackets. The risk of damage is limited when the etching agent is applied carefully.

Acid Etching, Dental↗
PubMed1989

Prevalence of TMJ symptoms and X-ray findings.

Some results of the fifteen year longitudinal Groningen study on TMJ dysfunction are reported. The prevalence of subjectively communicated symptoms appears to consistently increase with age. The recording of 21 percent pain at the last check-up was judged high. Objectively determined symptom frequencies (in the literature sometimes indicated signs) seem to level off in the early twenties. Observed X-ray deformities or flattening of the condyle did not increase substantially. The symptoms registered at the successive time points were found to originate to a considerable extent from changing individuals, indicating the unstable character of these symptoms. Furthermore the symptom categories are rarely present simultaneously in one individual. In harmony with these findings it appeared to be nearly impossible to predict any component by the same or any other component at an earlier time point. It is concluded that during growth, and probably due to growth, different signals appear. Some are outgrown, others are followed by serious problems; a third group may develop a new problem at maturity. Future research will be directed to identify these different groups at an early stage.

Adult↗
PubMed1987

Orthodontic treatment in relation to symptoms attributed to dysfunction of the temporomandibular joint. A 10-year report of the University of Groningen study.

This article reports a 10-year longitudinal investigation of symptoms attributed to temporomandibular joint dysfunction in orthodontically treated subjects. The study was designed to test the prevailing assumption that orthodontic therapy is an etiologic factor in inducing TMJ dysfunction. Although the study was prospective in design, several unexpected methodologic complications limited the data analyses. Presumed joint dysfunction symptoms were assessed in orthodontically treated subjects. The presumed symptoms were subsumed under three categories: subjective symptoms, objective symptoms, and x-ray findings. The prevalence of symptoms was analyzed before treatment, 4 years later subsequent to retention, and 10 years after the initiation of the study. Comparisons of symptom frequencies were made between Begg and activator-treated subjects. The results of this investigation led to the following conclusions. In studying temporomandibular joint dysfunction, subjective symptoms, objective symptoms, and x-ray findings should be analyzed separately. Registration of symptoms during orthodontic treatment should probably be attributed to age changes rather than to treatment procedures. Begg Class I and Class II treatments do not reduce the percentages of symptoms registered. Begg Class I and Class II treatments do not affect the incidence of subjective symptoms. Begg Class I and Class II treatments do not affect the incidence of x-ray findings. Begg Class I and Class II treatments create higher percentages of objective symptoms after retention, but not in the long run (10 years). Ten years after the beginning of treatment, the initial differences in symptomatology between activator and Begg children no longer exist.

Activator Appliances↗
PubMed1987

Helkimo's index: a scale or just a set of symptoms?

This article discusses the validity of indices, exemplified by Helkimo index, by means of a critical analysis of the assumptions that should be made for constructing an index. General principles of scale construction are applied to test the adequacy of the scale-values used for five common clinical symptoms in the Helkimo Di index. These general principles postulate that in addition to identifying patients correctly, an effective scale should also discriminate normal subjects. It is concluded that there is insufficient evidence to support the general applicability of this index. Further research concerning the properties of the index is needed. It is suggested that, since Helkimo's Di index contains many valuable elements, the discussion should be directed to improving the existing scale rather than trying to construct a new one.

Evaluation Studies as Topic↗