A phase II trial of pemetrexed (P), gemcitabine (G), and bevacizumab (BV) in untreated patients (pts) with advanced non-small cell lung cancer (NSCLC)

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Background: P and G are active agents with acceptable toxicity profiles in the treatment of NSCLC. The addition of BV to chemotherapy has resulted in a significant improvement in survival for pts with non-squamous NSCLC. We are currently conducting a phase II trial of P, G and BV on a novel every two week schedule in untreated pts with advanced NSCLC. Methods: Advanced, non-squamous NSCLC pts with measurable/evaluable disease, no prior treatment for advanced disease, PS 0–1, adequate hepatic, renal and bone marrow function, treated brain metastases were eligible. No unstable hypertension/cardiac disease/vascular disease, hemoptysis, anti-coagulation, recent major surgery, no cavitation or close proximity of primary cancer to a major vessel were allowed. Pts received P 500 mg/m2, G 1,500 mg/m2, and BV 10 mg/kg every 2 weeks for 12 cycles. Doses were reduced to P 400 mg/m2 and G 1,200 mg/m2 when grade 4 neutropenia occurred in the first 2 patients. BV was continued until disease progression or toxicity. Planned accrual is 42 patients. Primary endpoint is progression-free survival. Secondary endpoints are response rate (RR), toxicity, time to progression and overall survival. Results: 20 pts have been accrued. Median age 57.5 yrs, males-55%, stage IV 90%, adenocarcinoma 75%. 18 pts are response evaluable (2 were too early to assess). 11/18 (61%) pts had a response (1 CR, 7 PR, 3 unconfirmed PR) (90% CI for RR is 0.42 - 0.77), and 3 had SD ( 17%) for a disease control rate of 78%. Currently the median treatment cycles for all pts are 6 (range 1–12). All pts are evaluable for toxicity. Grade 3- 4 toxicities: neutropenia 4, anemia 1, thrombocytopenia 2, lymphopenia 1, febrile neutropenia 1, fatigue 4, hypertension 1, GI 2, ALT/AST 3, pneumonitis 1, muscular weakness 1, metabolic 2, otitis media 1. Conclusions: The combination of P, G, and BV is a very active and tolerable treatment for NSCLC despite the preliminary nature of these results. Updated information will be presented at the meeting. This research is supported by Lilly Oncology and Genentech.

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Preoperative chemoradiation and postoperative adjuvant tetrathiomolybdate for patients with resectable esophageal cancer

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Background: Tetrathiomolybdate (TM) is an oral copper chelator. Copper is necessary for blood vessel growth, and so TM functions as an antiangiogenic agent. Methods: Pts with resectable esophageal cancer were treated at the University of Michigan with chemoradiation followed by surgery, and then 2 years of TM. Chemoradiation was cisplatin 60 mg/m2 on days #1 and 22, paclitaxel 60 mg/m2 on days #1, 8, 15, and 22, and radiation 1.5 Gy fractions b.i.d. x 3 weeks to a total of 45 Gy. Transhiatal esophagectomy was performed on approximately day #50. TM 20 mg p.o. q.d. was started approximately 4 weeks post-op, and continued for 2 years. Doses were adjusted to maintain the ceruloplasmin level between 5 and 15. Results: Between 1/23/02 and 1/24/06, 69 pts were enrolled. Pt characteristics: males - 62 (90%), females - 7 (10%); median age - 60 (range 42–74); adenocarcinoma - 56 (81%), squamous cell carcinoma 13 (19%). The chemoradiation was well tolerated: grade 3 leukopenia in 15 pts (22%), and 17 pts (25%) required feeding tubes. 66 pts went to surgery. 61 pts had a complete resection; 4 pts had metastases discovered at surgery, and 1 pt had extensive positive margins. Histologic complete response rate was 10%. 21 pts never received TM because of metastases noted in the peri-operative period, long post-op recovery time, or pt refusal. 48 pts started TM after surgery and it was well tolerated. Grade 3 toxicities were diarrhea -2 (3%), nausea - 2 (3%), dizziness - 2 (3%). 13 pts completed the full 24 mos of treatment, 12 completed 10–23 mos, 15 completed 2–8 mos, and 8 completed only 1 month or less. 27 pts have had disease recurrence, the majority (23 of the 27) of which was distant. Current status of pts with median follow-up time of 55 months: 25 alive and disease-free, 1 alive with disease, and 43 have died. 3-year survival probability is 47% (95% CI 35%-58.6%). 3-year recurrence-free probability is 51% (95% CI 38%- 62.7%). Conclusions: TM is an antiangiogenic agent which is fairly well tolerated. Prolonged adjuvant treatment over 2 years is difficult but not impossible to complete. Disease-free survival and overall survival are promising when compared to historical controls treated with a very similar chemoradiation regimen without TM in the past at the University of Michigan.

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Phase I study of vorinostat plus docetaxel in patients with solid tumor malignancies

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Background: Vorinostat is an inhibitor of histone deacetylase 6, which results in the acetylation of tubulin and the stabilization of microtubules. Since taxanes bind to stabilized microtubules, the administration of vorinostat followed by docetaxel, we hypothesized, should result in synergistic cytotoxicity. A phase I trial was conducted to determine the dose level of vorinostat plus docetaxel that would result in dose-limiting toxicity (DLT) in ≤ 30% of patients (pts). Methods: Eligible pts had castration-resistant prostate cancer (CRPC) or relapsed urothelial or non-small-cell lung cancer (NSCLC) after ≥1 prior chemotherapy regimen not containing docetaxel, a performance status of 0–2 and adequate organ function. Vorinostat was given orally for 14 days beginning on day 1 of a 21-day cycle. Docetaxel was given intravenously over 1 hour on day 4. The time-to-event continuous reassessment method guided dose escalation. Dose levels (DL) -1, 0, 1 and 2 corresponded to vorinostat 100, 100, 200 and 200 mg plus docetaxel 50, 60, 60, and 75 mg/m2, respectively. Blood was collected on days 1 and 4 of cycle 1 to measure drug levels by HPLC. Results: 12 pts were enrolled: median age 65 yrs (49–74); gender 9M:3F; 4 CRPC, 5 urothelial, 3 NSCLC. The median number of cycles was 2. 2 pts were treated at DL -1, 4 pts at DL 0, 5 pts at DL 1 and 1 pt at DL 2. 5 DLTs occurred in 5 pts: grade 4 neutropenic fever/sepsis (n = 2), anaphylactic reaction (n = 1), myocardial infarction (n = 1) and GI bleed (n = 1). Other toxicities included grade 4 neutropenia (n = 2), pulmonary embolus (n = 1) and GI bleed (n = 1). The estimated probability of DLT for DL -1 was .32 (90% posterior probability interval [PI], .11 to .53) for DL 0, .38 (90% PI, .16 to .58) and for DL 1, .43 (90% PI, .23 to .64). The trial was stopped due to excessive toxicity. No responses were noted. Conclusions: Combination vorinostat plus docetaxel was poorly tolerated with excessive DLTs requiring study termination. PK analysis will be presented. Supported in part by a grant from Merck & Co., Inc.

[Table: see text]

Phase II trial of imatinib maintenance therapy after irinotecan and cisplatin in patients with c-kit positive extensive-stage small cell lung cancer (ES SCLC)

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Background: The prognosis for patients (pts) with ES SCLC is poor, with a median survival of 9 mo. This trial was designed to evaluate the efficacy and toxicity of cisplatin plus irinotecan followed by maintenance imatinib (Gleevec) in pts with c-kit positive ES SCLC. Methods: Immunohistochemistry for c-kit was performed on paraffin-embedded tissue prior to enrollment. Treatment consisted of irinotecan 65 mg/m2 IV on days 1 and 8 plus cisplatin 60 mg/m2 IV on day 1 repeated every 21 days for 4 cycles. If no evidence of disease progression was identified, Gleevec was given at 400 mg orally BID until disease progression or unacceptable toxicity. Results: 14 pts have been enrolled: median age 61 yrs (range 47–73); 9 men: 5 women; PS 0/1/2 = 3/10/1. 6 pts did not begin Gleevec due to disease progression (4), persistent grade 3 emesis (1), and referral for radiation therapy (1). 8 pts had a PR with cisplatin/irinotecan and received Gleevec. Median number of wks on Gleevec was 6.1 (range 4.6–25.1). Reasons for discontinuation of Gleevec were disease progression (7) and persistent neutropenia (1). Median progression-free survival was 4.7 mo. (range 0.7–16.3) for all pts and 5.5 mo. (range 4.7–16.3) for pts receiving Gleevec. There were no objective responses to Gleevec, but 3 pts (21%) had stable disease for 12, 15 and 25 wks. Median survival was 8.1 mo. (range 3.7–19.6) for all pts and 10.0 mo. (range 7.1–19.6) for those receiving Gleevec. Myelosuppression was mild (grade 1–2 ANC 13%, anemia 76%, platelets 13%) with one pt with grade 3 neutropenia. Non-heme toxicity included grade 1–2 nausea 76%, diarrhea 51% and peripheral edema 75%. Conclusions: Gleevec did not appear to maintain disease stability after response to chemotherapy in the majority of pts despite c-kit tumor positivity. Although disease stability with Gleevec was noted in 3 pts (12–25 wks) and therapy was well tolerated, this approach does not appear to warrant further clinical study. Supported by Novartis Pharmaceuticals.

No significant financial relationships to disclose.

Catalytic inhibition of human DNA topoisomerase IIalpha by hypericin, a naphthodianthrone from St. John's wort (Hypericum perforatum)

St. John's wort (Hypericum perforatum) is the most widely used herbal medicine for the treatment of depression. However, concerns have arisen about the potential of its interaction with other drugs due to the induction of cytochrome P450 isozymes 1A2 and 3A4 by the components hypericin and hyperforin, respectively. Structurally similar natural products are often employed as antitumor agents due to their action as inhibitors of DNA topoisomerases, nuclear enzymes that modify DNA during cellular proliferation. Preliminary findings that hypericin inhibited the DNA relaxation activity of topoisomerase IIalpha (topo II; EC 5.99.1.3) led us to investigate the mechanism of enzyme inhibition. Rather than stabilizing the enzyme in covalent complexes with DNA (cleavage complexes), hypericin inhibited the enzyme prior to DNA cleavage. In vitro assays indicate that hypericin is a potent antagonist of cleavage complex stabilization by the chemotherapeutics etoposide and amsacrine. This antagonism appears to be due to the ability of hypericin to intercalate or distort DNA structure, thereby precluding topo II binding and/or DNA cleavage. Supporting its non-DNA damaging, catalytic inhibition of topo II, hypericin was shown to be equitoxic to both wild-type and amsacrine-resistant HL-60 leukemia cell lines. Moreover, hypericin was incapable of stimulating DNA damage-responsive gene promoters that are activated by etoposide. As with the in vitro topo II assay, antagonism of DNA damage stimulated by 30 microM etoposide was evident in leukemia cells pretreated with 5 microM hypericin. Since many cancer patients experience clinical depression and concomitantly self-medicate with herbal remedies, extracts of St. John's wort should be investigated further for their potential to antagonize topo II-directed chemotherapy regimens.

A study in animal ethics in New Brunswick

Society uses animals in ever-increasing numbers and ways, providing ethical challenges. Decisions about animal use are guided by the social consensus ethic towards animals. Because there is no clear social consensus ethic, these decisions are difficult. Society's ethic is changing and a "new ethic" towards animals is emerging. This study addressed the need to better understand society's ethics towards animals. Qualitative research methodology (focus groups) was used to study 7 different animal-interest groups. Qualitative data analysis was computer-aided. The group ethical position towards animals of its own group interest was determined for each group. The animal welfare, companion animal, and veterinary groups took Rollin's Position, a position based on both the Utilitarian and the Rights Principles; the farmer and trapper groups the Utilitarian/Land Ethic position, a dual position based on actions producing the greatest amount of pleasure and the least amount of pain for the greatest number, and preserving the integrity, stability, and beauty of the biotic community; the hunter group the Utilitarian/Judeo-Christian position, a dual position based on actions producing the greatest amount of pleasure and the least amount of pain for the greatest number, and having dominion over animals; and the naturalist group took Rollin's Position/Land Ethic. All these groups perceived medium to extreme ethical responsibility towards animals of their own group's interest that are used by others. The study showed that the predicted "new ethic" towards animals is in New Brunswick society and it is Rollin's Position.

Cephalometric appraisal of posttreatment vertical changes in adult orthodontic patients

The purpose of this study was to evaluate vertical facial changes in adult orthodontic patients and to evaluate the stability of these changes. Thirty-three patients (8 males and 25 females) were examined. The patients had been treated with full fixed edgewise appliance mechanics and exhibited at least 1.0 degrees of clockwise rotation of the mandible during treatment. Mandibular rotation was determined by the angular change in the Y-axis to the Frankfort plane. Twelve angular and 14 linear skeletal and dental measurements and 3 skeletal ratios were derived from pretreatment (T1), posttreatment (T2), and postretention (T3) cephalometric radiographs. Paired t tests were used to compare vertical changes that occurred as a result of orthodontic treatment and their stability or relapse tendency during the retention and postretention periods. Twenty-five percent (P <.001) of the opening rotation of the mandible recovered during the posttreatment period, resulting in a significant overall rotation that was maintained. Both treatment and posttreatment changes in the Y-axis angle showed a high correlation with the horizontal position of pogonion (r = -0.797 and -0.889, respectively). Only overjet showed a low correlation between treatment changes and posttreatment changes in the Y-axis angle. Stepwise regression analysis of pretreatment variables and treatment changes failed to predict the behavior of the Y-axis angle change.

Core structure of the envelope glycoprotein GP2 from Ebola virus at 1.9-A resolution

Ebola virions contain a surface transmembrane glycoprotein (GP) that is responsible for binding to target cells and subsequent fusion of the viral and host-cell membranes. GP is expressed as a single-chain precursor that is posttranslationally processed into the disulfide-linked fragments GP1 and GP2. The GP2 subunit is thought to mediate membrane fusion. A soluble fragment of the GP2 ectodomain, lacking the fusion-peptide region and the transmembrane helix, folds into a stable, highly helical structure in aqueous solution. Limited proteolysis studies identify a stable core of the GP2 ectodomain. This 74-residue core, denoted Ebo-74, was crystallized, and its x-ray structure was determined at 1.9-A resolution. Ebo-74 forms a trimer in which a long, central three-stranded coiled coil is surrounded by shorter C-terminal helices that are packed in an antiparallel orientation into hydrophobic grooves on the surface of the coiled coil. Our results confirm the previously anticipated structural similarity between the Ebola GP2 ectodomain and the core of the transmembrane subunit from oncogenic retroviruses. The Ebo-74 structure likely represents the fusion-active conformation of the protein, and its overall architecture resembles several other viral membrane-fusion proteins, including those from HIV and influenza.

Effectiveness and duration of orthodontic treatment in adults and adolescents

The purpose of this investigation was to compare the effectiveness and duration of orthodontic treatment in adults and adolescents with a valid and reliable occlusal index. Another aim was to evaluate variables that may influence the effectiveness and duration of orthodontic treatment in general. Pretreatment and posttreatment study models were scored using the Peer Assessment Rating Index. The difference in scores between pretreatment and posttreatment stages reflects the degree of improvement and therefore the effectiveness of treatment. Variables that reflect patient compliance were recorded from written treatment records from three private orthodontic practices. The sample consisted of 32 adults (mean age, 31.3 years) and 40 adolescents (mean age, 12.9 years), all of whom had four premolars extracted as part of the treatment strategy. The results indicated that there were no statistically significant differences (P > .05) between adults and adolescents regarding treatment effectiveness (occlusal improvement) and treatment duration. Multiple regression techniques revealed that the number of broken appointments and appliance repairs explained 46% of the variability in orthodontic treatment duration and 24% of the variability in treatment effectiveness. Furthermore, orthodontic treatment of the buccal occlusion and overjet explained 46% of the variability in treatment duration.

A comparative study of anchorage in bioprogressive versus standard edgewise treatment in Class II correction with intermaxillary elastic force

The primary purpose of this study was to evaluate the effectiveness of cortical anchorage, by comparing two groups of patients with Class II malocclusions that were treated successfully with Class II elastics. One group of 30 previously treated patients had a utility arch used to set up cortical anchorage in the lower arch before Class II elastic wear; the second group was treated with standard edgewise mechanics where anchorage preparation consisted of full appliances, a well-aligned mandibular arch, and a rectangular arch wire. The groups were selected according to age, sex, and the amount of Class II elastic usage. Pretreatment and posttreatment cephalometric radiographs were used to generate 32 variables. A Student's t test was used to evaluate treatment change between the groups and revealed that there were no statistically significant differences. Lower molar teeth extruded and moved mesially equally in both groups. Although cortical anchorage did not retard lower molar movement, it was no less effective in controlling molar movement with a partial appliance than the fully banded standard edgewise appliance.

Opening rotations of the mandible during and after treatment

In this retrospective cephalometric study of mandibular rotational change, we studied 60 cases. All patients were treated with full fixed appliances and exhibited an opening rotation of at least 1.5 degrees during treatment, as measured on the basis of the angle of the Y-axis to the sella-nasion line (SN). Our objective was to determine whether this opening rotation was sustained during retention. Paired t tests were used to test the hypothesis that the treatment change or opening rotation was stable and that these patients did not return to their original mandible-to-cranium relationship in the posttreatment period. Stepwise regression analysis was used to determine which (if any) changes in the independent variables during treatment could predict the subsequent behavior of the angle of the mandibular plane to the SN and the angle of the Y-axis to the SN during retention. During treatment, the mean increase in the angle of the Y-axis to the SN was 2.43 degrees. After an average posttreatment period of 54 months, this angle was reduced on average by only 0.73 degrees. Stepwise linear-regression analysis indicated that none of the treatment changes seen in the independent variables strongly predicted the ensuing closing rotation seen during retention. The correlation coefficient between the Y-axis angle and the mandibular-plane angle during treatment was 0.67. Mandibular opening rotations as a consequence of orthodontic treatment do not invariably return to the pretreatment value, and their negative effects--although sometimes small--cannot be discounted. Because the preponderant evidence of a closing rotation occurs in the terminal pubertal growth stages, the net effect may be even more significant.

An assessment of treatment outcome in American Board of Orthodontics cases

In a retrospective study, 90 American Board of Orthodontic (ABO) cases were evaluated for treatment outcome. Changes in occlusion, cephalometric skeletal and dental variables, soft tissue variables, and root resorption were evaluated. The occlusions of completed ABO cases were compared with 147 naturally occurring good-to-excellent occlusions from the Andrews Foundation for Education and Research, using the Ideal Tooth Relationship Index (ITRI). Cephalometric variables were evaluated in relation to an "acceptable range" based on established standards. Photographs were evaluated for lip posture at rest and at closure, and the incidence and the severity of root resorption of maxillary and mandibular teeth excluding second molars were evaluated from panoramic radiographs. After treatment, occlusions of ABO cases scored significantly higher overall and for all ITRI segments except the anterior interarch segment when compared with Andrew's sample. In all the ABO cases, ideal overjet and overbite were attained. Cephalometrically, the mandibular plane and the Y-axis angle showed no significant change as a result of treatment. However, skeletal dysplasia (ANB) and skeletal convexity (Na-A-Po) showed improvement. Dentally, the maxillary incisor position and inclination, the interincisal angle, and the lower incisor position ended within the acceptable range, whereas the lower incisors were proclined. Soft tissue variables also improved, lip balance and harmony, closure at rest, and closure without strain all improved. The nasolabial angle showed little change. Most of the root resorption was minor in nature and involved the maxillary and mandibular central and lateral incisors. In conclusion, the ABO cases were well treated and showed marked improvement in occlusion, cephalometric, and soft tissue changes, although experiencing minor iatrogenic effects.

Verification of the role of PCP 4-monooxygenase in chlorine elimination from pentachlorophenol by Flavobacterium sp. strain ATCC 39723

The bacterial enzyme PCP 4-monooxygenase from Flavobacterium sp. strain ATCC 39723 catalyzes the oxygenolytic removal of the first chlorine from pentachlorophenol. PCP 4-monooxygenase is an FAD binding, NADPH requiring oxygenase, with similar functional domains as other bacterial flavoprotein monooxygenases specific for phenolic substrates. However, the definitive proof for the singular role of an oxygenolytic elimination of the primary chlorine from pentachlorophenol by Flavobacterium sp. has awaited the development of a genetic system whereby targeted mutagenesis via allelic exchange could be carried out with the corresponding gene from PCP 4-monooxygenase, pcpB. We report the development of a genetic system for Flavobacterium sp. strain ATCC 39723, and its application in targeted mutagenesis of the pcpB allele for elimination of PCP 4-monooxygenase activity.

Long-term stability after orthodontic treatment: nonextraction with prolonged retention

A sample of 22 previously treated orthodontic cases was studied to evaluate long-term stability. All cases were treated nonextraction with fixed edgewise appliances and were without retainers a minimum of 5 years. Data were obtained from study models, although 14 of the 22 cases had longitudinal cephalometric radiographs. The average retention time with a mandibular fixed lingual retainer was 8.4 years. The irregularity index pretreatment was 8.0 mm in the maxillary arch and 5.2 mm in the mandibular arch; at the end of treatment it was 0.9 mm and 1.0 mm, respectively, and at the postretention stage it was 2.0 mm and 2.4 mm, respectively. Resolution of the lower irregularity index was accomplished without incisor advancement or distal movement of the mandibular molar, however, both arches were expanded transversely. During the posttreatment stage all variables showed relapse except for the expanded maxillary canines and premolars. However, the mandibular anterior segment demonstrated relatively good alignment at the long-term stage, which may be a reflection of prolonged mandibular retention.

Detection of Clavibacter michiganensis subsp. sepedonicus by DNA amplification

Control of bacterial ring rot ultimately depends on the accurate and sensitive detection of C. michiganensis subsp. sepedonicus in infected potato tissues and tubers. Polymerase chain reaction (PCR) based detection of C. michiganensis subsp. sepedonicus appears to have the potential to circumvent many of the problems currently associated with detection of this phytopathogen. PCR reactions using primers specific to C. michiganensis subsp. sepedonicus and genomic DNAs from related strains, including phytopathogens, did not produce any amplification products. C. michiganensis subsp. sepedonicus was detectable from a mixture of potato and bacterial DNA by amplification of a DNA sequence specific to C. michiganensis subsp. sepedonicus. Detection by DNA amplification allowed direct processing of plant tissue samples, and circumvented the need for prior isolation of the suspected phytopathogen.

Comparison of Roth appliance and standard edgewise appliance treatment results

A retrospective comparison of Roth appliance and standard edgewise appliance treatment results was made using two indices. The first, the ideal tooth relationship index (ITRI), scored dental casts for the presence of ideal tooth contacts. The second judged posttreatment dental casts on the basis of criteria established by Andrews in his "Six Keys to Normal Occlusion." The sample consisted of 120 orthodontically treated cases completed by two practitioners who have used both the Roth and standard edgewise appliances. Thirty cases of each appliance type were collected from each practitioner. The overall posttreatment ITRI percentage scores showed no significant differences between the appliances. Practitioner differences existed for the anterior intraarch, anterior interarch, and posterior buccal interarch relationships. These differences were related to both treatment time and finishing arch wire size. The results of the Six Keys Analysis showed that the angulation and inclination of the maxillary posterior teeth were better with the Roth appliance. However, success in achieving some components of the six keys did not translate into an increased percentage of ideal tooth contacts as measured by the ITRI. Despite using the Roth appliance, experienced clinicians still found it difficult to achieve all six keys to normal occlusion.

Cloning, sequence analysis, and expression of the Flavobacterium pentachlorophenol-4-monooxygenase gene in Escherichia coli

The pcpB gene of Flavobacterium sp. strain ATCC 39723 was cloned by using a degenerate primer designed from the N-terminal sequence of the purified enzyme. The nucleotide sequence of pcpB was determined and found to encode an open reading frame of 1,614 nucleotides, yielding a predicted translation product of 538 amino acids, in agreement with the estimated size of the purified protein analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The transcriptional start of pcpB was found to be 80 bp upstream of the translational start, and the transcript was found to be induced in Flavobacterium sp. strain ATCC 39723 by the presence of pentachlorophenol but to be constitutive in the Escherichia coli pcpB clone. DNA hybridizations with genomic DNAs from Arthrobacter sp. strain ATCC 33790 and Pseudomonas sp. strain SR3 revealed a similar-size 3.0-kb EcoRI fragment, whereas there was no positive hybridization with genomic DNA from Rhodococcus chlorophenolicus. Cell extracts from an E. coli pcpB overexpression strain, as well as the whole cells, were proficient in the dechlorination of pentachlorophenol to tetrachlorohydroquinone. Protein data base comparisons of the predicted translation products revealed regions of homology with other microbial monooxygenases, including phenol-2-monooxygenase and tryptophan-2-monooxygenase.

Histological evaluation of the effect of transseptal fibre resection on the rate of physiological migration of rat molar teeth

Twenty-seven female Sprague-Dawley rats were given lead acetate as a vital stain, and rates of alveolar bone formation, representative of drift, were measured histologically. Teeth around which the transseptal fibre system had been destroyed drifted less quickly on both functioning (p less than 0.01) and non-functioning (p less than 0.001) sides than those with intact transseptal fibres. Both horizontal and vertical components of physiological drift were equally affected by destruction of the transseptal fibre system. It was felt that the transseptal fibres probably exerted their primary effect on the tooth, with bone remodelling around the drifting tooth being affected secondarily.

A static occlusal analysis based on ideal interarch and intraarch relationships

Study models were visually assessed to quantify the number of ideal tooth relationships actually present relative to the potential total. Both intraarch and interarch relationships were used to generate an ideal tooth relationship index (ITRI). Index scores were generated for the entire dentition, which could be divided into anterior, posterior, interarch, and intraarch relationships. Index scores were determined at various time intervals so the longitudinal changes could be studied. Treated orthodontic cases (n = 92) showed an initial total ITRI score of 26% that increased to 52% at the end of orthodontic treatment and continued to improve to 59% during the retention and postretention periods. Anterior segment scores were higher (64%) than posterior segment scores (44%). The intraarch relationships of the anterior segment registered the highest (75%), whereas the lingual cusp relationships of the posterior segment had the lowest scores (35%). Various types of malocclusions exhibited different ITRI scores before treatment but responded equally to treatment showing similar improvement in scores at the end of treatment and the posttreatment period.

Facial and dental arch asymmetries in Class II subdivision malocclusion

The purpose of this investigation was to determine if any significant differences existed with regard to dental arch and facial asymmetries between persons having malocclusions with well-defined asymmetric characteristics, specifically Angle's Class II subdivision malocclusions, and persons having normal occlusions. Secondarily, it was sought to determine the nature of the differences that contributed to the asymmetric occlusal relationship of buccal segments observed in Class II subdivision malocclusions. The sample consisted of 28 subjects in each of the two groups. All possessed a full complement of permanent teeth including first molars. The average age of subjects in both groups was 17 years. Measurements primarily of a linear nature were obtained from posteroanterior and lateral cephalometric radiographs in addition to dental models. Specific measurements were summed to produce various indices of asymmetry. Variables were analyzed with multivariate discriminant analysis. A significant discrimination between the two groups resulted; variables describing asymmetry of the dentoalveolar region of the mandible appeared to be the primary contributors to the difference obtained. Asymmetry of the maxillary dentoalveolar region appeared to make a secondary contribution.