Efficacy of collection methods in orthodontic practices.
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Chi-Square Distribution↗
Biomedical subjects
O C Tuncay
Publications and source records attributed to O C Tuncay.
Association of interleukin-1-induced, NF kappa B DNA-binding activity with collagenase gene expression in human gingival fibroblasts.
During earlier examination of interleukin-1 (IL-1)-induced matrix metalloproteinase gene expression in human gingival fibroblasts a highly induced immediate early gene, I kappa B-alpha, a NF kappa B DNA-binding inhibitor, was identified. The aim now was to investigate whether recombinant (r)IL-1 beta induces the stimulation of NF kappa B and its inhibitor proteins in human gingival fibroblasts and to understand if inhibition of its activity affects collagenase gene expression. Primary gingival fibroblasts (human) were treated with rIL-1 beta to determine the effect on NF kappa B-like DNA-binding activity. IL-1 induced the production of steady-state mRNA levels of I kappa B-alpha in the cultured fibroblasts. Nuclear run-on transcription studies demonstrated that rIL-1 induction of I kappa B-alpha may be transcriptionally regulated. Using electrophoretic mobility gel-shift assays it was shown that rIL-1 activates NF kappa B-like, DNA-binding activity in these fibroblasts. NF kappa B-like DNA-binding activity was rapidly induced and turned over in gingival fibroblasts with peak activity at 30 min after rIL-1 treatment. Further, treatment with chymotrypsin protease inhibitor and antioxidant inhibitor prevented IL-1-induced, NF kappa B-like, DNA-binding activity and collagenase mRNA production. When coupled with the existence of NF kappa B consensus DNA-binding sites on the collagenase gene promoter, these findings suggest that the stimulation of NF kappa B in gingival fibroblasts by rIL-1 could play an important part in the regulation of their collagenase gene expression. The ability of IL-1 to stimulate this expression may define a pivotal role for this cytokine in the pathogenesis of periodontitis.
Cells, Cultured↗
Validity of computerized predictions of dentoskeletal and soft tissue profile changes after mandibular setback and maxillary impaction osteotomies.
The aim of the present investigation was to evaluate the validity of the predictions of a computerized cephalometric system (Dentofacial Planner) regarding dentoskeletal and soft tissue profile changes after mandibular setback and maxillary impaction osteotomies. Tracings of lateral cephalograms taken at the end of preoperative orthodontics (within 1 week before surgery) and approximately 1 year after the operation were digitized and entered into the Dentofacial Planner. For the mandibular setback group, the computerized predictions tended to place the mandible less posteriorly than the actual situation and to significantly underestimate the mandibular plane angle, the total anterior skeletal and soft tissue facial heights, the lower anterior skeletal facial height, and the upper lip height. In the maxillary impaction group, the prediction printouts significantly overestimated the total anterior soft tissue facial height, the upper lip height and the inclination and curvature of the lower lip and underestimated the soft tissue thickness in the regions of pogonion and point B.
Adolescent↗
A "patient" patient: 22 years in bands.
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Adult↗
Implants from an orthodontic perspective.
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Dental Implants↗
How dentists perceive the effects of orthodontic extraction on facial appearance.
In recent years, orthodontic treatment, particularly that involving premolar extractions, has been alleged to cause flat facial profiles. Those who make such assertions also claim to be able to instantly identify from a distance faces of patients who have received orthodontic treatment. These are strong claims that could profoundly affect the public's perception of dentistry and its specialties. This study examined whether dentists could distinguish between profiles of treated and untreated patients as well as between patients who had undergone extraction and those who had not.
Analysis of Variance↗
Oxygen tension regulates osteoblast function.
Abrupt changes in oxygen availability within the periodontium have been suggested to have a regulatory role in alveolar bone remodeling during tooth movement; arguably, similar to that seen in bone growth or fracture healing. The purpose of this investigation was therefore to study the effects of ambient hypoxia and hyperoxia on osteoblast function in vitro. Osteoblast-enriched cultures from fetal rat calvariae were exposed to atmospheres of hyperoxia (90% O2) and hypoxia (10% O2) and assayed for media pH, pO2, pCO2, cellular proliferation, alkaline phosphatase (AP) activity, and collagen synthesis. Results of this study show that in low ambient oxygen tension cellular proliferation increases, whereas the AP activity, collagen synthesis, media pO2, PCO2 decreases. In contrast, in hyperoxic conditions cellular proliferation is suppressed with concomitant increases in: AP activity, collagen synthesis, and partial pressures for oxygen and carbon dioxide. Media pH remained unaffected. In crossover experiments, where cells were initially grown in hypoxic conditions and were switched to hyperoxic conditions, their metabolic activities were abruptly reversed. These findings in conjunction with earlier reports, suggest a triggering role for oxygen tension (an environmental factor) in bone remodeling.
Alkaline Phosphatase↗
Cytotoxicity of orthodontic elastics.
The neon-colored orthodontic rubber bands have recently become remarkably popular to wear among the young patients. In this study we examined if the dyes used in the manufacture of these elastics might exhibit any toxic effects. Gingival fibroblasts were exposed to extracts of colored and plain elastics in vitro. Cytotoxicity was examined by cellular proliferation rate and viability. Results showed that both the plain and the colored elastics display identical toxic effects. This ex vivo cytotoxicity, however, could not be observed in orthodontic patients: gingival fibroblast viability is no different in patients with and without rubber band wear. We conclude that in in vitro conditions, all orthodontic rubber bands are cytotoxic. Clinically, however, this effect is not demonstrable.
Adolescent↗
Gingival blood flow.
In the oral cavity extensive vascular changes accompany progression of gingival inflammation or healing and remodeling of periodontal tissues. This study was designed to explore how the gingival capillary circulation might be influenced by mechanical stimuli; specifically, tooth brushing. Changes in blood flow subsequent to mechanical stimulus of brushing were measured by laser Doppler flowmetry at the midline, canine and premolar regions of maxillary and mandibular arches. Results showed that tooth brushing increased the blood flow in these regions by approximately 60 percent relative to the resting state. These changes, however, were shortlived. Fifteen minutes following this mechanical stimulus the capillary circulation returned back to within ten percent of baseline readings. We conjecture that frequently applied mechanical stimuli might aid in gingival remodeling, high tissue turnover and metabolic rate.
Bicuspid↗
Apparatus criticus: methods used to evaluate growth modification in Class II malocclusion.
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Humans↗
Referral of patients for orthodontic treatment.
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Child↗
Scanning microfluorimetric measurements of redox status in the rat dento-alveolar tissues.
The oxidative state of periodontal tissues in situ is not known. Scanning microfluorimetry uses NADH fluorescence readings to provide a measure of a tissue's oxidative metabolic activity. Digitally recorded fluorescence signals were compiled to create a distribution map for this reduced pyridine nucleotide in the periodontal structures, which was then related to the morphology as seen by SEM. To distinguish between NADH fluorescence and intrinsic fluorescence of collagen, as well as to study the effect of oxygen deprivation, mitochondrial oxidative activity was inhibited by CO in some animals. Oxidative status and sensitivity to changes in cellular energy metabolism in the dento-alveolar complex were tissue specific; differences between tissues may play a part in the differential remodelling of the periodontium.
Alveolar Process↗
Methods used to evaluate growth modification in Class II malocclusion.
The methods used to study growth modification in orthodontic patients can have considerable impact on the conclusions that may be drawn. Because of the large "between-patient" variation and small mean changes usually observed, apparent differences in response may sometimes be more attributable to study design than to treatment effectiveness. A systematic review of four major orthodontic journals (1980 to 1987) identified 50 studies reporting treatment of young patients with Class II malocclusion. Variables defined to classify the studies included appliance systems, patient selection, comparison groups, research design, data collection, analysis, and reporting. The appliance systems most frequently investigated were the function regulator and the activator, used with and without headgear. Only 11 (22%) studies were prospective, and random assignment to alternative treatments was never used in this sample. Comparison groups used in 76% of the studies were untreated Class II patients (n = 18) and/or patients with alternate appliance systems (n = 17). In only 24% of the reports were groups tested for pretreatment equivalence. Few studies reported fully how patients had been selected, how decisions had been made to discontinue or change treatment, or whether patients had been lost to study. While most studies reported "p values," in only four were alpha levels adjusted for the number of tests (type I error), and no study included a post beta estimate (type II error). Age, sex, maturation, and duration of treatment were usually reported but seldom adjusted for in the analyses. Given the multiple indices of treatment effect, the generally small sample sizes, weak research designs, and incomplete reporting of important data, we cannot yet conclude whether orthodontic treatment influences the growth of Class II patients.
Data Collection↗
A review of clinical research in orthodontics.
The orthodontic journals should provide valid and reliable information that helps clinicians make appropriate decisions about patient care. The nature of the published literature has not been categorized. The American Journal of Orthodontics and Dentofacial Orthopedics (formerly the American Journal of Orthodontics) was reviewed for the years 1976, 1981, and 1986, to determine the frequency of clinical articles, the topics reported, the study designs used to obtain information, the senior author affiliation, and the major funding sources. This review demonstrates that more than half the articles in this Journal report data on patients, with the majority focusing on the evaluation or description of therapeutic interventions. Academic institutions contribute the majority of the clinical research, although only a few student theses are published. The major support for this work continues to be from departmental resources with little external funding. Despite the introduction of powerful research designs such as randomized clinical trials, these methods have not been widely adopted for orthodontic clinical research. The case report (study containing fewer than 10 patients with no control nor comparison group) continues to be the most frequently published format. Clinicians should become aware of the inherent weakness in the research designs generally used and recognize the limited information that can be obtained from such methods. Support for this research needs to be greatly expanded if the more powerful type of study required to provide valid and reliable clinical information is to be continued.
Epidemiologic Methods↗
Linkage between energy status of perivascular cells and mineralization of the chick growth cartilage.
The objective of this investigation was to investigate the relationship between the energy status of epiphyseal chondrocytes of the chick growth cartilage and the development of mineralization. A microfluorimetric scanning technique was used to measure the reduced pyridine nucleotide content of transverse sections of freeze-trapped cartilage; these measurements were related to tissue structure by scanning electron microscopy. The results of this study show that the energy status of cells in the hypertrophic region of the growth cartilage is more complex than was previously believed. In hypertrophic cartilage, most chondrocytes are in a reduced state. However, in the early hypertrophic region, the vascular channels that penetrate the cartilage from the metaphysis exert a profound local effect on the energy metabolism of perivascular chondrocytes. Thus, around each of the channels, there exists a zone of chondrocytes about 40-60 micron wide which exhibits a low fluorescence yield. The fluorescence level suggests that these perivascular cells have a higher level of oxidative metabolism than hypertrophic chondrocytes that are a distance (greater than 150 micron) from the vascular channels. This finding, in conjunction with our earlier observation that mineralization is first seen in the perivascular region, leads us to the conclusion that mineralization is associated with cellular oxidative activity. We now reject the long-held concept that in cartilage the development of mineralization is entirely due to tissue hypoxia.
Animals↗
The effect of gingival fiberotomy on the rate of tooth movement.
This study was designed to assess the gingival tissue resistance to remodeling in determining the rate of orthodontic tooth movement. Closed coil spring orthodontic appliances were stretched bilaterally between the first molars and incisors in the maxillary arches of 18 adult rats. The resistance of gingival tissues was eliminated around the randomly chosen first molars by a circumferential fiberotomy procedure. Movements of teeth were measured on submental vertex radiographs against the metallic implants that were placed in zygomatic processes. The data were analyzed by randomized block design analysis of variance. During the 30-day experimental period, the teeth that underwent the fiberotomy procedure moved faster (0.63 mm versus 0.51 mm, P less than 0.05), indicating that the resistance of gingival tissues may be a rate-limiting factor in orthodontic tooth movement.
Animals↗
The effect of indomethacin (an aspirin-like drug) on the rate of orthodontic tooth movement.
Prostaglandins (PGs) have been suggested as mediators of bone resorption. In addition, their presence in the periodontal tissues has also been demonstrated. To characterize the involvement of PGs in orthodontic tooth movement, indomethacin, an aspirin-like drug and a potent inhibitor of PG synthesis, was administered orally to six mongrel cats; another group of six animals served as controls. These animals were fitted with orthodontic appliances that consisted of coil springs stretching between the right side maxillary and mandibular canines and third premolars. The data for tooth-movement measurements were analyzed by repeated measures factorial analysis of variance. At the end of the 21-day experimental period, the rate of tooth movement in experimental animals was approximately one half of controls (P less than 0.01). Findings of this study imply a significant role for PGs in bone resorption during orthodontic therapy. It is recommended that aspirin-like drugs not be administered to patients undergoing orthodontic tooth movement as it may extend the treatment time.
Alveolar Process↗
Effects of diazepam on orthodontic tooth movement and alveolar bone cAMP levels in cats.
Cyclic AMP has been suggested as a possible intracellular mediator in bone remodeling during tooth movement. Accordingly, an increase in the level of this nucleotide should result in faster tooth movement. Breakdown of cAMP was inhibited by administration of diazepam in eight cats undergoing orthodontic tooth movement; another matched group of eight animals served as controls. Orthodontic appliances consisted of coil springs stretching between the right side maxillary and mandibular canines and third premolars. The data for tooth movement and cAMP concentrations were analyzed by repeated measures factorial analyses of variance. The results indicated that administration of diazepam increased the rate of tooth movement at P less than 0.0005 and, interestingly, although diazepam had no effect on undisturbed tissues, it lowered the cAMP levels in the periodontal tissues of orthodontically moved teeth at P less than 0.01. On the basis of these results, it was concluded that the concentration of cAMP did not correlate with bone remodeling in this model and perhaps should not be used as an index of periodontal-tissue response during orthodontic tooth movement.
Alveolar Process↗