Very early face mask therapy in Class III children.

The purpose of this study was to examine the effects of very early face mask therapy in children with Class III malocclusion. At pretreatment (T0), 40 female subjects who were eventually treated showed a more severe Class III pattern (ANB 0.1 degrees) than did 28 skeletal Class III female subjects who remained untreated (ANB 0.4 degrees), as observed in the Wits analysis. Posttreatment results (T1) showed significant (p<0.01) anterior advancement of the maxillary components, backward rotation of the mandible without increased lower anterior facial height, and an improved incisor relationship. Comparison of posttreatment (T1) and postretention (T2) records, however, revealed no increase in SNA in the treated group. SNA did increase in the untreated group, with no significant difference in ANB angle. The x-components of B-point and Me showed a significant (p<0.05) difference between the two groups. At postretention (T2), N-S-Ba, N-S-Ar, and CC-Ba tended to increase more in the treated group than in the untreated group.

Two unilateral complete cleft lip and palate orthodontic cases treated from birth to adolescence.

These two cases, one extraction and one nonextraction, demonstrate the present day status of a treatment protocol initiated, refined, and modified for the past 30 years. Using the combined and coordinated services of surgeon and orthodontist from the time of birth, individuals born with complete clefts of the lip and palate now have a better possibility of full esthetic and functional use of all of their maxillary permanent anterior dentition.

Long-term assessment of early alveolar bone grafts using three-dimensional computer-assisted tomography: a pilot study.

Fifteen patients with complete unilateral cleft lip and palate who had primary alveolar bone grafting were studied with computer-assisted tomography at a mean age of 12 years. Keeping the maxillary alveolar crest parallel to the plane of the scan, 1.5-mm cuts of the maxilla were made from the infraorbital rim to the gingival third of the crowns of the teeth. A single operator reformatted the data into three-dimensional images using the Maxiview 3200 computer workstation. This allowed examination of the position, size, and spatial relationship of the grafted area and quantification of the amount of bone coverage of root surface and bone height of the alveolus in or adjacent to the graft site. Ten patients showed a lateral incisor in the line of the cleft. The average bony coverage of these tooth roots was 76.5 percent. In the five patients in whom there was lateral incisor agenesis, the canine root had average bony coverage of 82.6 percent. The average height of bone at the lateral incisor was 8.7 mm; at the canine, 14.1 mm. In two patients in whom there was only 42 percent tooth root coverage, the teeth were still viable, stable, and without mobility. Computed tomographic (CT) scans of the 15 patients demonstrated good graft survival with adequate volume. The functional and aesthetic status of the dentition in the area of the cleft also was demonstrated.

Comparison of 2-D calculations from periapical and occlusal radiographs versus 3-D calculations from CAT scans in determining bone support for cleft-adjacent teeth following early alveolar bone grafts.

OBJECTIVE: This investigation was conducted to determine the agreement between three-dimensional (3-D) calculations from CAT scans and two-dimensional (2-D) calculations from standard dental radiographs in evaluating bone support for cleft-adjacent teeth after primary bone grafting. DESIGN: This retrospective study utilized CAT scans and dental radiographs taken of the alveolar cleft in patients an average of 11 years after primary bone grafting. SETTING: The subjects were patients treated by the Cleft Palate Team at Children's Memorial Hospital and Loyola University Medical Center, Chicago, Illinois. PATIENTS: Fourteen UCLP patients (9 males, 5 females) agreed to participate in this study by undergoing CAT scan assessment of their alveolar cleft sites. They also had to have periapical or occlusal radiographs of the grafted cleft site taken within 6 months of the CAT scan. INTERVENTIONS: All patients underwent primary lip repair, placement of a passive palatal plate, primary alveolar bone grafting (mean age 6.4 months), and palatoplasty before 1 year of age. Major tooth movement through final orthodontics was completed by the time of the radiographic assessment. MAIN OUTCOME MEASURES: CAT scan sections were reformatted and reconstructed to three-dimensionally calculate the percentage of root covered by bone support for the 15 teeth adjacent to the graft cleft sites. Dental radiographs of the same teeth were also traced and digitized. Percentages of root supported by bone were also established using the dental radiographs by dividing the amount of root covered by bone, by the anatomic root length. RESULTS: A paired, two-sample t test revealed no significant differences between the two methods of assessment, while linear regression showed a statistically significant correlation between the CAT scan assessment and the percentages found on the radiographs. CONCLUSIONS: Routine dental radiographs were able to estimate the total 3-D bone support for the roots of cleft adjacent teeth as determined by CAT scan to a statistically significant degree when groups where compared. The clinical significance for evaluation of individual cases was less impressive with a wide range of variability and a level of agreement that required acceptance of differences up to 25%.

Hepatitis delta virus ribozymes fold to generate a solvent-inaccessible core with essential nucleotides near the cleavage site phosphate.

Self-cleaving sequences or ribozymes from the hepatitis delta virus (HDV) genomic RNA and its complement form similar secondary structures that suggest a core region and potential active site composed of "single-stranded" sequences. However, there is little data on tertiary interactions in these ribozymes, therefore structural features were investigated using cross-linking and hydroxyl radical cleavage. Cross-links in cis and trans forms of the antigenomic RNA were generated using the photoactivatable azidophenacyl group tethered to the cleavage site phosphate. Specific cross-links formed to J4/2, and to the 3' sides of P3 and L3. Different sites were cross-linked in low salt or monovalent cations versus divalent cations, suggesting a metal ion-dependent conformational change near the cleavage site. The solvent-inaccessible regions of both the genomic and antigenomic ribozymes were revealed by cleavage in Fe(II)-EDTA. In Mg2+, backbone segments most strongly protected from solvent-based hydroxyl radicals were mapped to J4/2 and parts of L3. Similar patterns of protection were seen in trans-acting ribozymes bound to a product oligonucleotide. These data provide evidence for a common tertiary structure for the HDV ribozymes. They would be consistent with a model in which the end of P1, including the cleavage site phosphate and the nucleotide 5' to the cleavage site, is positioned in an active site pocket or cleft formed by the three single-stranded regions, L3, J4/2, and J1/4.

Comparison of facial form in primary alveolar bone-grafted and nongrafted unilateral cleft lip and palate patients: intercenter retrospective study.

The purpose of this study was to describe and compare posttreatment craniofacial morphology in samples of complete unilateral cleft lip and palate (CUCLP) patients treated at two leading clinics: The Children's Memorial Hospital Cleft Palate Clinic, Chicago, Illinois, and the Lancaster Cleft Palate Clinic, Lancaster, Pennsylvania. These centers have well-defined treatment protocols that allow the long-term effects on craniofacial form of the following treatment regimes to be contrasted: (1) Chicago--primary alveolar bone grafting, with definitive lip repair at age 4 to 6 months and hard and soft palate repair at 6 to 12 months; and (2) Lancaster--definitive triangular-flap lip repair at 3 months of age, followed by staged surgeries of the hard and soft palates, both completed by 18 months of age, but without primary alveolar bone grafting. Although the Lancaster center now performs secondary alveolar bone grafting, the majority of the patients studied here were treated before this procedure became part of their protocol. Patients were eligible for inclusion if they had no other congenital anomalies and no previous orthodontic treatment. A sample of 43 (24 male, 19 female) CUCLP patients was obtained from the Chicago Center, each of which was then matched to a nongrafted Lancaster CUCLP patient. The matching criteria were age, sex, and sella-nasion distance (to control, at least in part, for size differences). Lateral cephalometric radiographs of these 86 CUCLP patients were traced, digitized, and analyzed. Additionally, all linear data were adjusted to a standard magnification of 8% because the cephalograms from each center featured different enlargements. The Chicago and Lancaster samples had mean posttreatment ages of 10.32 years (SD = 1.96) and 10.40 years (SD = 2.18), respectively. The grafted Chicago group had faces that were on average less maxillary protrusive compared with the nongrafted Lancaster sample; it appeared, however, that the mandible compensated for the maxillary position by downward and backward rotation. As a result, a similar maxillomandibular relationship was noted in both groups, although, in the Chicago group, the lower anterior facial height increased.

A Class II, division 1 malocclusion offering a myriad of treatment options. What would you have done?

This young man presented for treatment with an orthodontic problem that did not necessarily command a straight forward, uncomplicated plan even though the diagnosis and Angle classification of his problem did. The fact that so many options are available reaffirms once again that orthodontic treatment planning in the face of definitive records is indeed as much an art of personal conviction as well as scientific dictum.

Experimental evidence for the secondary structure of the hepatitis delta virus ribozyme.

Specific features of a model for the secondary structure of the self-cleaving RNA sequences (ribozymes) of hepatitis delta virus were rigorously tested. Using a self-cleaving form of the antigenomic sequence, mutations were made in the 5' and 3' sequences of each of four duplex regions within the proposed ribozyme structure. Precursor RNA from each variant sequence was prepared and the kinetics of cleavage in 10 mM Mg2+ at 37 degrees was examined. The data was quantified to determine an end point and a first-order rate constant for cleavage with each mutant by fitting the data to the exponential form of the first-order rate equation. With regard to the final extent of cleavage, most mutations in these regions appeared to have little effect, however, the kinetics indicated that disruption of the potential for basepairing resulted in dramatic decreases in the rate constant for cleavage. These results are consistent with the idea that most of the mutations affected ribozyme activity rather than an equilibrium between precursor and cleavage products. Mutations that reduced rates were compensated by changes that restored the potential for Watson-Crick pairing. Ribonuclease probing of ribozyme variants containing mismatches and compensatory changes allowed direct correlation of structural changes with the mutations. This provided an independent validation of the functional kinetic assay. Thus, site-directed mutagenesis was consistent with a proposed ribozyme secondary structure containing 4 distinct base-paired regions.

Secondary structure of the self-cleaving RNA of hepatitis delta virus: applications to catalytic RNA design.

A model for the secondary structure of the self-cleaving RNA from hepatitis delta virus was tested. Specific base changes were introduced in each of four regions with the potential for base-pairing (stems I-IV), and for each variant sequence, a rate constant for cleavage was determined. In each stem, mutations that would interfere with Watson-Crick base-pairing also reduced the first-order rate constants by 10-10(4)-fold relative to the unmodified version. Within stems I and II and a shortened form of stem IV, compensatory changes resulted in rates of cleavage equal to or greater than the unaltered ribozyme sequence. Stem III compensatory mutants cleaved faster than the uncompensated mutants although they were not as active as the natural sequence, suggesting additional sequence-dependent requirements within this region. Structure probing of RNA containing the stem II mutations provided an independent confirmation of stem II in the ribozyme. The predictive value of the model was tested by designing two trans-acting ribozymes which were circularly permuted composites of genomic, antigenomic, and unique sequences. The core of these two catalytic RNAs was the same, but they otherwise differed in that, in one of them, a constraining tetraloop sequence was added to stem II. Both ribozymes catalyzed the trans cleavage of a substrate oligoribonucleotide, thus providing additional evidence for stem II and the proposed structure in general.

Evidence that genomic and antigenomic RNA self-cleaving elements from hepatitis delta virus have similar secondary structures.

The two sequences that define the self-cleaving elements from the genomic and antigenomic RNA of hepatitis delta virus were folded into secondary structures with similar features. Evidence in support of the two models was obtained from limited ribonuclease digestion of genomic and antigenomic RNA fragments containing the sequence 3' of the cleavage site. Under conditions where the rates of self-cleavage are enhanced by addition of 5 M urea (2-10 mM Mg2+ at 37 degrees C), ribonucleases T1, U2, A and V1 generated digestion patterns consistent with the proposed RNA structures. The evidence for a relatively stable structure in urea when Mg2+ is present suggests that denaturant-enhanced rates of self-cleavage could result from destabilization of competing inactive structures.

Orthognathic surgery in cleft patients treated by early bone grafting.

For the past 25 years at Children's Memorial Hospital in Chicago a protocol has been followed for complete clefts that involves placement of an infant maxillary orthopedic appliance prior to lip closure, surgical closure of the lip, autogenous split-rib grafts to the alveolus to stabilize maxillary segments, and palatal closure, generally within the first year of life. The oldest 36 patients whose skeletal growth was for all practical purposes finished have been followed to determine the need for and type of orthognathic surgery. Of the total sample, 8 patients (22.2 percent) required some type of sagittal orthognathic surgery (1 patient in this group also required vertical maxillary alignment) and 2 patients required maxillary augmentation only in the form of an onlay graft. This report may serve as a baseline for others who wish to report on the incidence and type of orthognathic surgery in their cleft palate centers.

The case for early bone grafting in cleft lip and palate: a second report.

In 1982, the first long-term study of our early bone-grafting and infant maxillary orthopedic approach to newborn complete clefts of the lip, alveolus, and palate was published. The protocol and sequence of procedures were shown on the first 16 consecutively treated orthodontic patients, with a mean age of 14 years. Cephalometric analysis evaluated anteroposterior and vertical facial growth. This report follows the next 37 consecutively treated individuals in a similar manner and includes not only 20 complete unilateral clefts, but also 17 complete bilateral clefts. Results, when evaluated alone and in comparison with the original series, show once again that there are no adverse growth restraints and that early primary bone grafting in our protocol leads to teeth in better overall occlusion than if it had not been undertaken.

Self-cleavage of hepatitis delta virus genomic strand RNA is enhanced under partially denaturing conditions.

Self-cleavage of a polyribonucleotide containing an autocleaving sequence from the genomic strand of hepatitis delta virus was enhanced by conditions that destabilized RNA structure. Self-cleavage of the transcripts used in this study required Mg2+ (or another divalent cation), and in the absence of denaturants, maximum cleavage was observed at very low Mg2+ concentrations (0.05-0.1 mM). However, at 37 degrees C and in the presence of 2-10 mM Mg2+ the rate of cleavage was increased as much as 50-fold with the addition of urea to 5 M or formamide to 10 M. Cleavage was prevented by higher concentrations of the same reagents (9.5 M urea or 22.5 M formamide), presumably because a structure required for self-cleavage is disrupted by strongly denaturing conditions. In contrast to a previous report [Wu, H.-N., & Lai, M. M. C. (1989) Science 243, 652-654], we find that chelating Mg2+ with EDTA terminates the cleavage reaction without promoting measurable amounts of ligation of the cleavage products. The ability of denaturants to promote rapid self-cleavage in vitro raises the possibility that an unidentified factor could have a similar effect in vivo.

Parental predictions of their children's knowledge about dangerous situations.

This study explored the extent to which parents can predict their 5-, 8-, and 12-year-old male and female children's responses to questions about safe and dangerous situations. A total of 68 children and 61 parents of these children were questioned about their children's knowledge of (1) home address/telephone number, (2) strangers, (3) what to do in various emergency situations, (4) trust in police, (5) compliance towards police, and (6) resistance towards strangers. Parents were most accurate in predicting their children's understanding of strangers and trust in police officers. Parents overestimated their 5-year-olds' knowledge of home address/telephone and appropriate behaviors when lost or in abduction situations. Parental overestimations of knowledge and the likelihood to behave safely were more frequent with boys than with girls. Parental underestimations of children's knowledge of certain types of avoidance actions also were found. The results were interpreted in terms of metacognition and sex differences in spatial freedom.