The effect of morphine on orthodontic tooth movement in rats.

OBJECTIVES: To investigate the effect of morphine as an exogenous opioid on orthodontic tooth movement. Naltrexone will be used as an opioid antagonist to confirm the results. METHODS: Forty rats were randomly divided into four equal groups. The first group received no injection; the second group received daily injections of morphine; the third group received daily naltrexone-morphine injections and the fourth group daily injections of naltrexone-normal saline. The left first maxillary molar in each rat was tipped mesially with a NiTi closed coil spring. The rats were sacrificed after 14 days and the maxillae fixed, sectioned serially and examined histologically. RESULTS: The greatest amount of tooth movement occurred in the Control group and the least amount of tooth movement in the Morphine group. Tooth movement in the Morphine group was significantly different from the other three groups (p < 0.05). The differences in tooth movement in the Control, Morphine-naltrexone and Naltrexonesaline groups were not statistically significant (p > 0.05). No statistically significant histological differences were found. CONCLUSIONS: Morphine reduced orthodontic tooth movement in rats. This effect was reversed by the opioid antagonist, naltrexone, which had no effect on tooth movement.

Comparison of occlusal balance contacts in patients treated with standard edgewise and preadjusted straight-wire appliances.

This study investigated the functional occlusion in two groups of patients treated to a Class I canine and molar relationship by fixed appliance therapy. Group A consisted of 24 patients treated with standard edgewise appliances, whereas the 15 patients in group B were treated with a straight-wire appliance. The occlusal contacts were assessed intraorally with articulating ribbon of 8 microns thick. All procedures and measurements were performed by the same examiner. The results revealed that balancing contacts were significantly more frequent in group A. In both groups, most subjects had balancing contacts between their second molars (P<.05). The prevalence of posterior protrusive contacts in group A was similar to group B. Most of the subjects in group B demonstrated canine guidance on laterotrusion, whereas in group A, the majority exhibited group function (P<.05). Mutually protected occlusion was present in an overwhelming percentage of group B, as compared to no patient in group A (P<.05). Patients treated with edgewise appliances did not exhibit ideal functional occlusal relationships, whereas most individuals after straight-wire appliance therapy had a mutually protected (ideal) occlusion.

Comparison of wire loop and shear blade as the 2 most common methods for testing orthodontic shear bond strength.

INTRODUCTION: The purpose of this study was to compare 2 common methods of measuring orthodontic shear bond strength. METHODS: Brackets were bonded to 40 bovine incisors, and the teeth were mounted in a jig. The teeth were paired for symmetry, and the pairs were divided into 2 groups for debonding. In group 1, the shear force was applied with a rectangular wire under the tie wings. In group 2, a shearing blade applied force to the junction between the bracket base and the adhesive. RESULTS: Debonding with the shear blade produced higher (24.86 +/- 7.44 MPa) and more dispersed (coefficient of variation = 29.91%) bond strengths compared with the wire loop (17.12 +/- 3.16 MPa, coefficient of variation = 18.44%). Adhesive remnant index (ARI) scores showed a tendency for cohesive failure in the enamel in the shear-blade group (ARI = 5) compared with adhesive failure (ARI = 3) in the wire group. CONCLUSIONS: There is a need to standardize bond strength tests. The results of this study favor the wire-loop method, which might have more similarity to clinical loads. The regression formula might make comparison of previous studies easier.

Introduction of a new orthodontic treatment planning software; a fuzzy logic expert system.

General practitioners can learn the mechanical aspects of orthodontics quickly. But they are not usually sure about the treament plans they propose. In this article, new software is described that proposes treatment plans fornon-surgical orthodontic cases. This computer program can receive patients' data in both graphical and numerical forms. The concepts of fuzzy logic have been used to enable the software to work with nominal parameters. This feature greatly simplifies the use of the software because it does not force the user to measure several numerical variables. Each patients' data is saved by this software and the saved data can be modified or deleted later. The computer program is prepared to deal with special cases such as incomplete dentitions appropriately. The software is supposed to reduce the number of inappropriate extractions and erroneous treatment plans for orthodontic purposes.

Orthodontic treatment planning software.

A new software is described that can receive patient data in both graphic and numeric forms and then propose a treatment plan for nonsurgical orthodontic patients. The concepts of fuzzy logic enable the software to work with nominal parameters; the human brain is naturally accustomed to fuzzy variables. The computer program can propose treatment for some special cases, such as incomplete dentition.

Prediction of arch perimeter changes due to orthodontic treatment.

A borderline orthodontic case with mild to moderate space deficiency can be treated without extractions. Expansion can be used to relieve space deficiency. The prediction of arch perimeter change for a given amount of expansion is helpful in planning the treatment of a patient who needs expansion, and it can facilitate nonextraction orthodontic treatment. To date, different amounts of arch perimeter change have been proposed for the same amount of expansion. A computer program is explained in this study, and examples of its uses are given. By entering 4 parameters of a dental arch into the computer program before and after an orthodontic procedure, one can simply calculate the total and the anterior arch perimeters and see the differences between them numerically and graphically. The program can save, print, change, and delete the calculated data for each patient. For clinicians who do not choose to use the computer program, 2 regression formulas are also presented to calculate the anterior and the total dental arch perimeters. The perimeters of 23 pairs of well-aligned dental arches were measured to check the accuracy of the computer program and the formulas. Paired t tests did not show statistically significant differences between the actual, the computer-derived, and the formula-derived perimeters of the dental arches at 95% confidence level.

Extrusion-based leveling with segmented arch mechanics.

Leveling of the dental arch may be accomplished through anterior intrusion, posterior extrusion, or a combination. Posterior extrusion is usually preferred in vertically balanced adolescents and in surgical-orthodontic treatment of adults suffering from deep bite and mandibular deficiency. A major disadvantage of posterior extrusion, when accomplished by continuous archwires, is incisor flaring. Here a segmented arch arrangement is proposed for posterior extrusion that combines the clinical simplicity of continuous mechanics with better control of incisor position.