Health in Down syndrome: creating a conceptual model.

BACKGROUND: Down syndrome (DS) has a unique medical and psychological profile that could impact how health is defined on three dimensions: physical, social and mental well-being. METHODS: In 2021, we presented our proposed conceptual model to three expert panels, four focus groups of parents of individuals with DS age 0-21 years and four focus groups of individuals with DS age 13-21 years through videoconferencing technology. Participants gave feedback and discussed the concept of health in DS. RESULTS: Feedback from participants resulted in iterative refinement of our model, retaining the three dimensions of health, and modifying constructs within those dimensions. Experts and parents agreed that individuals with DS have unique health concerns that necessitate the creation and validation of a syndrome-specific health model. We present key themes that we identified and a final conceptual model of health for individuals with DS. CONCLUSION: Health in DS is a multi-dimensional, multi-construct model focused on relevant constructs of causal and effect indicators. This conceptual model can be used in future research to develop a syndrome-specific measure of health status.

UV-induced mutagenesis at the hypoxanthine-guanine phosphoribosyl transferase locus in two L5178Y mouse lymphoma cell strains with different UV sensitivities.

Two strains of L5178Y mouse lymphoma cells, L5178Y-R (LY-R) and L5178Y-S (LY-S), differ markedly in their sensitivity to 254 nm UV radiation (D0 = 0.7 and 5.5 J/m2; n = 6.0 and 2.0 for LY-R and LY-S cells, respectively). In this study, the frequency of hypoxanthine-guanine-phosphoribosyl-transferase-deficient mutants was determined, using 6-thioguanine (TG) as a selective agent, in populations of LY-R and LY-S cells exposed to various fluences of UV radiation. The spontaneous mutation frequency for LY-R cells was (3.7 +/- 0.6) X 10(-5) TGr mutants per viable cell, and the UV induction rate was (2.2 +/- 0.8) X 10(-4) TGr mutants per viable cell, per J/m2. Both spontaneous and induced mutation frequencies were much lower for LY-S cells. The spontaneous mutation frequency for these cells were too low to make its measurement practicable (less than 0.0013 X 10(-5) TGr mutants per viable cell). Mutation induction rate was (4.2 +/- 2.2) X 10(-7) TGr mutants per viable cell, per J/m2. These differences in mutability do not appear to be due to gene duplication in LY-S cells, or to selective growth disadvantage of LY-S-derived TG-resistant mutants. Possible mechanisms underlying the differences in mutability of LY-R and LY-S cells are considered.

Toxicity and mutagenicity of radiation from fluorescent lamps and a sunlamp in L5178y mouse lymphoma cells.

Unfiltered broad spectrum radiation emitted by black light, cool white, and black light blue fluorescent lamps and a sunlamp, is both toxic and mutagenic to L5178Y mouse lymphoma cells when the cells are irradiated in phosphate-buffered saline. The increase in mutant frequency seen after exposure of the cells is linear throughout the range of exposures tested. The linear increase in mutagenesis is observed even at exposure levels which do not cause significant toxicity. To facilitate comparison of the differing rates of mutagenesis derived from exposure-response curves obtained for each light source, we have defined a parameter, joule-equivalent mutagenesis (jem), equal to mutants per 10(5) survivors per joule per square meter. Jem values are calculated using the integrated irradiance of each lamp. Based on jem values, the relative mutagenicity of the various lamps tested (compared with a germicidal ultraviolet lamp) is 3 x 10(-3) for the sunlamp, 1 x 10(-4) for the black light and cool white lamps, and 3 x 10(-5) for the black light blue lamp. The toxic and mutagenic effects of the lamps are in reasonable agreement with their relative spectral output from 290 to 330 nm.

Temporary reversal by topotecan of marked insulin resistance in a patient with myelodysplastic syndrome: case report and possible mechanism for tumor necrosis factor alpha (TNF-alpha)-induced insulin resistance.

Tumor necrosis factor-alpha (TNF-alpha) is an important mediator of insulin resistance in obesity and diabetes through its ability to decrease the tyrosine kinase activity of the insulin receptor. We report here a remarkable degree of insulin resistance in a patient with adult respiratory distress syndrome and myelodysplasia.

An in vitro comparison of five root canal length measuring instruments.

Several new root canal length measuring instruments (RCLMI) have recently been introduced claiming superiority over older systems. The purpose of this study was to compare five models of these instruments with respect to their accuracy under a given set of specified conditions. The five RCLMI tested were: the, Exact-a-pex, the Endocater, the Neosono-D, the Apex Finder, and the Sono-Explorer, Mark III. The conditions tested were the accuracy of the instruments in determining the working length, the consistency of measurement following canal instrumentation and with conductive gutta-percha points in place, and the operation of the RCLMI in the presence of fluids frequently found in root canals during endodontic treatment. An in vitro model was used to test these instruments. A set of 20 teeth was tested using the conditions specified above. All data were compared using the mean difference from the actual canal length of the teeth. The results indicated that there were no significant differences among measurements derived from the five instruments, under the specified conditions. There was a slight variation of the measurements by all instruments when they were used following instrumentation and with the use of conductive gutta-percha points. When fluids were present in the canals, the reliability of the RCLMI depended on the electrical conductivity of the fluid tested. The poorest results were obtained when either sodium hypochlorite or blood were present in the canals.

A safe technique for removal of provisionally cemented crowns.

A technique is presented for removing full-cast crowns and porcelain crowns that have been temporarily or provisionally cemented. A rubber dam retainer clamp with rubber dam attached is placed on the crown and clamped near its margins. Steiglitz forceps are used to apply pressure and leverage. The assembled unit is removed with the Steiglitz and safely removes the loosened crown from the mouth.

Ultrasonic condensation of gutta-percha: an in vitro dye penetration and scanning electron microscopic study.

Lateral condensation of gutta-percha with and without ultrasonic activation of the spreader was compared by use of dye penetration analysis and scanning electron photomicrographs of the gutta-percha fills in extracted human incisors and canines. The root canal fillings in three groups of 10 teeth each were laterally condensed using an ultrasonically activated spreader, a fine finger spreader, or a non-activated ultrasonic spreader. Significantly less apical dye penetration occurred when teeth were obturated using an ultrasonically activated spreader as compared with manual condensation with fine finger spreaders. The ultrasonically condensed gutta-percha mass was more homogeneous with fewer voids compared with gutta-percha masses from the two groups that were condensed without ultrasonic activation. A correlation between apical microleakage and the appearance of the gutta-percha mass was seen. All teeth with well-condensed, more homogeneous fillings had low dye penetration. All teeth with a high extent of dye penetration had poorly condensed, less homogeneous fillings. However, not all teeth that had poorly condensed fillings had high dye penetration.

A comparison between Thermafil and lateral condensation in highly curved canals.

The obturation of highly curved canals often poses a problem for the clinician using lateral condensation. Recently, a product that incorporates guttapercha with a carrier (Thermafil) has been marketed. This study asked, "Was there a difference in apical microleakage of highly curved canals obturated with the Thermafil versus lateral condensation?" Twenty-two extracted human molars with canal curvature greater than 30 degrees were instrumented using a step-back technique. Teeth were placed in two groups of 10 teeth. Two teeth were controls. Canals were either obturated using sealer and lateral condensation, or sealer and the Thermafil technique. The access was closed with Cavit. Teeth were coated with wax and placed into India ink for 48 h. The wax was removed and teeth were cleared. All teeth were evaluated for linear dye penetration using a x7 viewer. A t test resulted in t = 0.137 (p > 0.05). Mean leakage for teeth obturated with the Thermafil was 1.15 mm and was 1.09 mm for lateral condensation. The Thermafil technique resulted in similar dye penetration to lateral condensation in highly curved canals.

Anatomical and histological features of C-shaped canals in mandibular second molars.

The mandibular second molar has many root canal variations. This investigation used two evaluation methods to examine the canal morphology of mandibular second molars having C-shaped canals. Fifteen extracted mandibular second molars with a conical root and C-shaped canal orifice were separated into two groups. A polyester cast resin technique allowed three-dimensional visualization of the root canal system in eight teeth; the remaining seven molars were prepared for histological examination in cross-section in the coronal, middle, and apical thirds for study under the light microscope. The results illustrated that C-shaped canals in mandibular second molars can vary in number and shape along the length of the root with the result that debridement, obturation, and restoration in this group may be unusually difficult.

Vasculature of the dental pulp of atherosclerotic monkeys: light and electron microscopic findings.

Arteriosclerosis is a pathological condition in which there is a severe luminal narrowing of arterioles, resulting in tissue ischemia and necrosis. Arteriosclerosis has been reported in the dental pulp of normotensive persons as young as 40 yr of age. To date, no corroboration of these findings have been published. Our study examined pulp from atherosclerotic monkeys for such changes under controlled conditions. The lingual artery and canines from 11 nonatherosclerotic (control) and 11 atherosclerotic (experimental) cynolmolgus monkeys were histologically evaluated with light and transmission electron microscopy. Lingual arteries from controls did not exhibit atherosclerotic plaques, whereas those of the experimental monkeys did show fibro-foamy plaques. However, neither experimental nor control animals exhibited any arteriosclerotic alterations in the pulp. Our study concluded that, in this animal model, which did demonstrate atherosclerosis in the oral cavity, no similar alterations were found in the pulp.

Accuracy of the Endex with variations in canal irrigants and foramen size.

Several electronic apex locators (EALs) are currently available. The manufacturer of a new device, the Endex, claims that it is accurate regardless of canal conditions. This study compared the accuracy of the Endex with that of the Exact-a-pex, the Sono-Explorer Mark III, and the Neosono-D SE as to the effects of fluids in the canal and variation in foramen size. Sixty extracted single-canaled teeth were divided into two groups (narrow and wide foramina), depending on whether the apical foramina permitted the tip of a #30 K file to pass through. An in vitro model was used, in which teeth were fitted in test tubes with the roots immersed in 1% agar in phosphate-buffered saline. Root canal lengths were measured in dry canals, then with ethanol, Xylocaine, and sodium hypochlorite in the canals by each electronic apex locator. These lengths were compared with those of the actual root canal lengths. No significant differences were noted among the instruments in dry canals regardless of the foramen size. The endex was generally superior to the other instruments examined in canals containing conductive fluids, especially where the apical foramen was widened.

Clinical evaluation of five electronic root canal length measuring instruments.

A previous in vitro study has shown high accuracy, but no clinically significant differences in a group of five electronic root canal length measuring instruments. The purpose of this study was to evaluate and compare the performance of the same group of instruments under clinical conditions and to correlate their accuracy to radiographic estimates of canal length. Five electronic root canal length measuring instruments were used to measure the working length to the "apex" in 20 single-rooted teeth scheduled for extraction. After extraction, the actual canal length was measured visually to a point just within the apical foramen. This length was compared with instrument length as determined electronically. The accuracy of the instruments in determining canal measurement within +/- 0.5 mm from the apical foramen varied from 55 to 75%. The differences between the instruments were not statistically significant. On average, all of the instruments except for the Endocater gave canal length measurements that were beyond the apical foramen. The variability of the measurements, which was comparable to that of estimates of canal length from preoperative radiographs, indicated that radiographic verification of the working length is still desirable.

An evaluation of root canal treatment in patients who have received irradiation to the mandible and maxilla.

OBJECTIVE: The purpose of this study was to evaluate the success and failure of root canal treatment performed in areas of previous irradiation and to examine any cases of osteoradionecrosis associated with such treatment. STUDY DESIGN: A retrospective analysis was done on 22 teeth that had root canal treatment after radiation therapy. Strict radiographic and clinical criteria were used to determine success and failure. RESULTS: There was a mean follow-up period of 19 months. Of 22 cases, 20 (91%) were considered successful. Both failures occurred with a diagnosis of pulpal necrosis. There were no occurrences of osteoradionecrosis. CONCLUSIONS: Our study showed that root canal treatment in previously irradiated patients may be successful. In addition, treatment approaches, as well as the criteria for success and failure, should be the same for irradiated patients as for those who have not received radiation treatment.

Mandibular molars with five canals: report of two cases.

A mandibular first and second molar found to contain five root canals are described. Recent literature pertaining to unusual root canal morphological structure is reviewed and a recommendation is made for a complete and thorough examination of the chamber floor for even seemingly straightforward and simple nonsurgical endodontic cases.

Regional variation in permeability of young dentin.

Variation in the permeability of dentin in people 19 years and less in age was evaluated. The regions compared were the occlusal third versus the middle third versus the cervical third of approximal surfaces. Also compared were the mesial approximal surface versus the distal. The comparison was done by obtaining 1 mm-thick dentin discs from the area of dentin close to the dentinoenamel junction. It was seen that the cervical area was significantly more permeable than the occlusal area. The middle third, though not statistically significant, had mean values almost twice those in the occlusal third and almost half of the values in the cervical third. No difference was seen in permeability between the mesial and distal surfaces. The reasons for these regional variations and their clinical implications are presented.

Effect of dentin desensitizers and dentin bonding agents on dentin permeability.

PURPOSE: To determine the effect of dentin desensitizing agents (oxalates and glutaraldehyde) and dentin bonding agents, with and without resin-based composite (RBC) on dentin permeability and morphology of the dentin surface. The influence of saliva and toothbrushing on these agents was also evaluated. MATERIALS AND METHODS: Radicular dentin discs +/-1 mm thick were obtained from extracted human teeth. The thickness of the discs was standardized by grinding them with 600 grit silicon carbide powder. Both pulpal and periodontal surfaces of the discs were treated with 6% citric acid for 2 min prior to the baseline measurement of dentin permeability. Permeability was measured for the discs, using a split-chamber apparatus, at four different time points: at baseline, after treatment with each desensitizing modality, after 24 hrs of saliva immersion and after simulated toothbrushing equivalent to 3 weeks of normal brushing. The treatment modalities were: Sensodyne Dentin Desensitizer, Gluma Dentin Desensitizer, All-Bond DS (primers without etching), Etch+Primers (All-Bond 2 system), Etch+Primers+Adhesive and Etch+Primers+Adhesive+RBC (AElite Flo). Radicular dentin discs were prepared separately for scanning electron microscopy (SEM). One group was left untreated as the control group. Discs in the other groups were treated with the modalities listed above. One disc from each group was viewed under the SEM after treatment with the desensitizing modality. The second disc in each group was viewed after 24 hrs of saliva immersion following desensitizing treatment and the third disc after 3 weeks of simulated toothbrushing following desensitizing treatment and saliva immersion. RESULTS: The greatest reduction in permeability was caused by All-Bond DS followed by Sensodyne Dentin Desensitizer and Etch+Primers+Adhesive+RBC. Gluma Dentin Desensitizer, Etch+Primers, and Etch+Primers+Adhesive did not reduce permeability by a significant amount. Saliva immersion increased permeability significantly only for the Gluma and Etch+Primers+Adhesive groups. There was a trend towards increase in permeability after toothbrushing; however, this increase was not statistically significant for any group (P > 0.05). Thus, placement of primers without etching (All-Bond DS) reduced permeability more than any other treatment modality. These data indicate that etching a sensitive dentin area may be appropriate only if RBC is to be placed in the area. Exposure to saliva and toothbrushing countered the decrease in permeability caused by dedicated desensitizers and dentin bonding agents. The SEM micrographs revealed that in most cases, form corroborated function and the morphology of the dentin surface corresponded to the dentin permeability values.