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Biomedical subjects

J Hickman

Publications and source records attributed to J Hickman.

At least 19 recordsLinked to original sources
PubMed2006

Adhesives for fixed orthodontic bands.

BACKGROUND: Orthodontic treatment involves using fixed or removable appliances (dental braces) to correct the positions of teeth. It has been shown that the quality of treatment result obtained with fixed appliances is much better than with removable appliances. Fixed appliances are, therefore, favoured by most orthodontists for treatment. The success of a fixed orthodontic appliance depends on the metal attachments (brackets and bands) being attached securely to the teeth so that they do not become loose during treatment. Brackets are usually attached to the front and side teeth, whereas bands (metal rings that go round the teeth) are more commonly used on the back teeth (molars). A number of adhesives are available to attach bands to teeth and it is important to understand which group of adhesives bond most reliably, as well as reducing or preventing dental decay during the treatment period. OBJECTIVES: To evaluate the effectiveness of the adhesives used to attach bands to teeth during fixed appliance treatment, in terms of:(1) how often the bands come off during treatment; and(2) whether they protect the banded teeth against decay during fixed appliance treatment. SEARCH STRATEGY: Electronic databases were searched: the Cochrane Oral Health Group's Trials Register (July 2005), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 2, 2005), MEDLINE (1966 to July 2005) and EMBASE (1980 to July 2005). A search of the internet was also undertaken. There was no restriction with regard to publication status or language of publication. SELECTION CRITERIA: Randomised and controlled clinical trials (RCTs and CCTs) (including split-mouth studies) of adhesives used to attach orthodontic bands to molar teeth were selected. Patients with full arch fixed orthodontic appliance(s) who had bands attached to molars were included. DATA COLLECTION AND ANALYSIS: All review authors were involved in study selection, validity assessment and data extraction without blinding to the authors, adhesives used or results obtained. All disagreements were resolved by discussion. MAIN RESULTS: Five RCTs and three CCTs were identified as meeting the review's inclusion criteria. All the included trials were of split-mouth design. Four trials compared chemically cured zinc phosphate and chemically cured glass ionomer; three trials compared chemically cured glass ionomer cement with light cured compomer; one trial compared chemically cured glass ionomer with a chemically cured glass phosphonate. Data analysis was often inappropriate within the studies meeting the inclusion criteria. AUTHORS' CONCLUSIONS: There is insufficient high quality evidence with regard to the most effective adhesive for attaching orthodontic bands to molar teeth. Further RCTs are required.

Adhesives↗
PubMed2004

Fluidics-resolved estimation of protein adsorption kinetics in a biomicrofluidic system.

Protein adsorption on surfaces is a complex phenomenon that is described by the balance of convective/diffusive transport of the protein species to the surface and its adsorption/desorption at the surface. The extent of binding depends on a variety of factors such as protein/surface interactions, availability of binding sites, localized concentrations of protein near biomaterial surfaces and flow characteristics of the protein in that region. Factors such as time-varying flows, complex device geometries, presence of multiple competitive species, or possible denaturing of proteins when they attach to the surface make it extremely difficult to quantitatively analyze protein interactions with surfaces. Adsorption/desorption rate constants are often inferred using simplistic models which neglect mass transport and have limited use across different microfluidic systems and flow protocols. In this work, we have developed and demonstrated a fluidics-resolved model that evaluates protein adsorption, accounting for both the fluidic transport and the biochemical kinetics in complex biomicrofluidic devices. The model is valid for both flow and static conditions. An automated procedure was also developed to extract the "intrinsic" mass-transport-independent adsorption kinetic rate constants from experimental data using a least squares optimization method. The automated data extraction methodology is applied to two proteins (alkaline phosphatase and glucose oxidase) that have been brought into contact with poly(etheretherketone) and Teflon capillaries. The applicability of the procedure in analyzing flow and adsorption in complex microfluidic structures is also demonstrated.

Adsorption↗
PubMed2003

Adhesives for fixed orthodontic brackets.

BACKGROUND: Bonding of orthodontic brackets to teeth is important to enable effective and efficient treatment with fixed appliances. The problem is bracket failure during treatment which increases operator chairside time and lengthens treatment time. A prolonged treatment is likely to increase the oral health risks of orthodontic treatment with fixed appliances one of which is irreversible enamel decalcification. OBJECTIVES: To evaluate the effectiveness of different orthodontic adhesives for bonding. SEARCH STRATEGY: Electronic databases: the Cochrane Oral Health Group's Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE. Date of most recent searches: August 2002 (CENTRAL) (The Cochrane Library Issue 2, 2002). SELECTION CRITERIA: Trials were selected if they met the following criteria: randomised controlled trials (RCTs) and controlled clinical trials (CCTs) comparing two different adhesive groups. Participants were patients with fixed orthodontic appliances. The interventions were adhesives that bonded stainless steel brackets to all teeth except the molars. The primary outcome was debond or bracket failure. DATA COLLECTION AND ANALYSIS: Data were recorded on decalcification as a secondary outcome, if present. Information regarding methods, participants, interventions, outcome measures and results were extracted in duplicate by pairs of reviewers (Nicky Mandall (NM) and Rye Mattick (CRM); Declan Millett (DTM) and Joy Hickman (JH2)). Since the data were not presented in a form that was amenable to meta-analysis, the results of the review are presented in narrative form only. MAIN RESULTS: Three trials satisfied the inclusion criteria. A chemical cured composite was compared with a light cure composite (one trial), a conventional glass ionomer cement (one trial) and a polyacid-modified resin composite (compomer) (one trial). The quality of the trial reports was generally poor. REVIEWER'S CONCLUSIONS: It is difficult to draw any conclusions from this review, however, suggestions are made for methods of improving future research involving orthodontic adhesives.

Dental Cements↗
PubMed2002

Powered vs manual tooth brushing in fixed appliance patients: a short term randomized clinical trial.

Sixty-three orthodontic patients wearing upper and lower fixed appliances were randomly assigned to use either a powered toothbrush fitted with a modified orthodontic brush head (Braun Oral-B Plaque Remover 3D) or a manual toothbrush (Reach Compact Medium). A trained hygienist instructed each patient on the proper use of the allocated brush. Measurements of plaque and gingival health were made at baseline, at four weeks, and at eight weeks. Data for each group were analyzed using paired t-tests. Patients using the powered toothbrush showed a significant reduction in percentage interdental bleeding scores from baseline to four weeks (-12.7, P = .003) and this was still apparent at eight weeks (-8.6, P = .028), although there were no statistically significant changes in either plaque or gingivitis scores for this group. Those patients using a manual toothbrush showed a significant reduction in mean plaque score from baseline (four weeks = -0.18, P = < .001; eight weeks = -0.12, P = .016), but gingivitis scores were only reduced significantly at four weeks. In this group, interdental bleeding scores reduced significantly at four weeks (P = .028), but were not significantly different from baseline at eight weeks (P = .0319). When the two patient groups were compared using two sample t-tests, there were no significant differences in any of the parameters measured at any time point in the study. Over an eight-week period, there were no measurable differences between the powered toothbrush with modified orthodontic brush head and a manual toothbrush with respect to mean change in plaque, gingivitis, or interdental bleeding scores when used by patients wearing fixed appliances.

Adolescent↗
PubMed2002

Orthodontic adhesives: a systematic review.

OBJECTIVES: To evaluate which orthodontic adhesives (a). bond orthodontic brackets to teeth more reliably and (b). are more effective at preventing decalcification. DATA SOURCES: The search strategy for the literature review was carried out according to the standard Cochrane systematic review methodology. The Cochrane Clinical Trials Register and the Cochrane Oral Health Group Specialized Register were searched for randomized clinical trials and controlled clinical trials. All volumes that had not already been assessed by the Oral Health Group in the European Journal of Orthodontics, American Journal of Orthodontics, Journals of Orthodontics, and Angle Orthodontist were hand-searched. Inclusion and exclusion criteria were applied when considering the studies to be included in this review. DATA SELECTION: The primary outcome measure was the failure of the orthodontic adhesive. A secondary outcome of decalcification occurring around the orthodontic bracket was also recorded, if data were available. DATA EXTRACTION: Two randomized clinical trials and one controlled clinical trial were identified that fulfilled all the inclusion and exclusion criteria. The trials compared: (a). light- and chemically-cured composite; (b). chemically-cured composite and conventional glass ionomer cement; and (c). chemically-cured composite and light-cured compomer. DATA SYNTHESIS: Each paper was quality assessed by two people independently. A qualitative analysis of the trials in the review is presented. The data presentation, for the majority of the trials, precluded the use of suggested Cochrane Health Group statistical analysis. CONCLUSIONS: It is difficult to draw any conclusions from this review; however, suggestions are made for methods of improving future research involving orthodontic adhesives.

Compomers↗
PubMed2001

A validated finite element method study of orthodontic tooth movement in the human subject.

The aim of the study was to develop a 3D computer model of the movement of a maxillary incisor tooth when subjected to an orthodontic load. A novel method was to be developed to directly and accurately measure orthodontic tooth movement in a group of human volunteers. This was to be used to validate the finite element-based computer model. The design took the form of a prospective experiment at a laboratory at the University of Wales in 1996/7. A laser apparatus was used to sample tooth movement every 0.01 seconds over a 1-minute cycle for 10 healthy volunteers, whilst a constant 0.39 N load was applied. This process was repeated on eight separate occasions and the most consistent five readings taken for each subject. Data were used to calculate the physical properties of the periodontal ligament (PDL). The data gleaned by this method were used to validate the 3D FEM model. This was formed of 15,000 four-noded tetrahedral elements. Tooth displacements ranged from 0.012 to 0.133 mm. An appropriate elastic modulus of 1 N/mm(2) and Poisson's Ratio of 0.45 was derived for the PDL. Strain analysis, using the model, suggested that a maximum PDL strain of 4.77 x 10(-3) was recorded at the alveolar crest, while the largest apical strain recorded was 1.55 x 10(-3). The maximum strains recorded in the surrounding alveolar bone were 35 times less than for the PDL. A novel method for direct measurement of PDL physical properties in the human subject has been developed. The validated FEM model lends further evidence that the PDL is the main mediator of orthodontic tooth movement.

Adult↗
PubMed2001

Therapeutic studies with a new combination benzoyl peroxide/clindamycin topical gel in acne vulgaris.

Three independent clinical studies were conducted in more than 1250 patients with moderate to moderately severe acne vulgaris to evaluate the efficacy and safety of a new combination gel that stably combines 5% benzoyl peroxide and 1% clindamycin. The results indicated that the benzoyl peroxide/clindamycin combination product was an effective treatment for reducing the inflammatory and noninflammatory lesions of acne vulgaris. In overall improvement as rated by the physicians and patients, the combination gel was superior to clindamycin alone, and in 2 of the 3 studies, to benzoyl peroxide alone. The antimicrobial activity of the combination gel was significantly (each P < .01) superior to that seen with topical application of its individual constituents, 5% benzoyl peroxide or 1% clindamycin, and was numerically better than that found with topical application of a 5% benzoyl peroxide/3% erythromycin combination product. As with benzoyl peroxide, dry skin was the most frequent side effect with use of the combination gel, with isolated incidences of other localized irritation. No other safety or tolerability concerns were identified.

Acne Vulgaris↗
PubMed2001

Marked antitumor activity of a new potent acronycine derivative in orthotopic models of human solid tumors.

S 23906-1 is a novel acronycine derivative selected on the basis of its potency in vitro. We investigated the antitumor activity of S 23906-1 against several murine transplantable tumors (C38 colon carcinoma, P388 leukemia, B16 melanoma, and Lewis lung carcinoma) and in orthotopic models of human lung (NCI-H460 and A549), ovarian (IGROV1 and NIH:OVCAR-3), and colorectal cancers (HCT116 and HT-29). Against established C38 colon carcinoma, S 23906-1 administered twice i.v. from 1.56-6.25 mg/kg markedly inhibited tumor growth. Treatment at the optimal dose (6.25 mg/kg) induced tumor regression in all of the mice. Acronycine was 16-fold less potent and only moderately active at the maximum tolerated dose, 100 mg/kg. Against other murine tumors of the former National Cancer Institute panel, S 23906-1 was either only moderately active or totally inactive. When evaluated in human orthotopic models, S 23906-1 given p.o. or i.v. demonstrated a marked antitumor activity against human carcinomas. In the two human lung cancer models, S 23906-1 increased the survival of the animals in a dose-dependent manner and induced treated versus control values of 162% (NCI-H460) and 193% (A549). Vinorelbine was less active, with treated versus control values of 119% and 174%, respectively. A significant survival benefit was also observed against the two i.p. ovarian tumors in which S 23906-1 was as active as paclitaxel, inducing 80% long-term survivors in the NIH:OVCAR-3 model. Lastly, S 23906-1 inhibited the growth of primary HT-29 and HCT116 colon tumors grafted onto the cecum as efficiently as irinotecan and eradicated the formation of lymph node, hepatic, and pulmonary metastases in the aggressive HCT116 model. The novel spectrum of activity of S 23906-1 compared with existing anticancer agents warrants further preclinical investigation.

Acronine↗
PubMed2000

Linear hyperechogenicity within the basal ganglia and thalamus of preterm infants.

Linear hyperechogenicity (LHE) within the basal ganglia and thalamus is an uncommon sonographic finding in preterm infants and is of unclear significance. The study objectives were to determine the clinical characteristics and neurodevelopmental outcome in preterm infants who develop LHE. Ten preterm and 20 control infants were evaluated developmentally at 18 months adjusted age using the Bayley Scales of Infant Development. LHE was diagnosed at 4 weeks (range = 1-11). Antenatal glucocorticoid therapy was more common in infants with LHE than in the control infants (90% vs 45%). Four (44%) of nine LHE infants and no control infants were positive for cytomegalovirus (P = 0.02, and three of 10 LHE infants and no control infants had a hypothyroid (P = 0.03). The mental development scores and behavioral evaluation results were lower in the infants with LHE than in the control infants (73.7 +/- 9.7 vs 83.7 +/- 9.4, P = 0.01 and 23.7 +/- 20.1 vs 43.9 +/- 25.4, P = 0.04, respectively). The infants without LHE also had poorer motor quality (22.8 +/- 20. 5 vs 55.7 +/- 37.4, P = 0.02) and lower emotional regulation scores (25.7 +/- 16 vs 42.3 +/- 24, P = 0.06) than the control infants. Preterm infants with LHE are at an increased risk of adverse neurodevelopmental outcome and, in particular, cognitive and behavioral performance. The sonographic evolution of LHE may be a marker of a diffuse insult to the brain.

Basal Ganglia↗
PubMed1998

Ketoconazole 2% shampoo in the treatment of tinea versicolor: a multicenter, randomized, double-blind, placebo-controlled trial.

BACKGROUND: Tinea versicolor is a common superficial fungal infection caused by a lipophilic yeast. This chronically recurring opportunistic infection is especially prevalent in tropical and semitropical regions. The topical short-term application of ketoconazole 2% shampoo may provide effective and safe therapy for tinea versicolor. OBJECTIVE: The purpose of this study was to evaluate the efficacy and safety of a single application (1 day) versus three daily applications (3 days) of ketoconazole 2% shampoo versus placebo shampoo in the treatment of mycologically confirmed tinea versicolor. METHODS: Three hundred twelve patients were included in the primary analyses for this 31-day study. Global evaluation scores were measured on days 10 and 31 with a 5-point scale (1 = healed to 5 = worsening), and a cellophane tape test was done at baseline and days 3, 10, and 31. Efficacy was assessed by clinical response, defined as both a global evaluation score of 1 (healed) and a negative cellophane tape test on day 31. Signs and symptoms of tinea versicolor (scaling, itching, erythema, hypopigmentation, hyperpigmentation) also were evaluated at baseline, day 10, and day 31 with a 4-point scale (0 = absent to 3 = severe). RESULTS: Both regimens of ketoconazole shampoo were significantly (P < .001) more effective than placebo for rate of clinical response, global evaluation scores, and mycologic outcomes (cellophane tape test). The clinical response rates at day 31 were 73%, 69%, and 5% for the 3-day ketoconazole, 1-day ketoconazole, and placebo groups, respectively. The difference in the efficacy of the two ketoconazole treatment regimens was not statistically significant. There were no significant differences between any of the treatment groups in the number of patients who experienced adverse events. No serious adverse events occurred and no patient withdrew from the trial prematurely because of an adverse event. CONCLUSION: Ketoconazole 2% shampoo, used as a single application or daily for 3 days, is safe and highly effective in the treatment of tinea versicolor.

Adolescent↗
PubMed1997

Sore throat.

Explore the source record for details and available documents.

Humans↗
PubMed1994

The elastic modulus of dentine determined by static and dynamic methods.

The purpose of this investigation was to determine a static elastic modulus of dentine using a three point beam test and a dynamic modulus in the frequency range of 0.1 Hz and 10 Hz across a temperature range of 27-37 degrees C. At body temperature, the mean static modulus was 8.6 GPa, (standard deviation 0.86 GPa). The dynamic test produced a range of modulus values. At 0.1 Hz the modulus ranged from 14.3 to 15.2 GPa; for 1.0 Hz the range was 14.6-15.5 GPa and for 10 Hz the range was 14.9-15.8 GPa. The results are of value in the design and analysis of restorative materials.

Biomechanical Phenomena↗
PubMed1994

Characterization of radiation-induced apoptosis in the small intestine and its biological implications.

The small intestine with its high cell proliferation, well-accepted hierarchy, high radiation susceptibility and low cancer incidence is a useful model for studying the controls of cell replacement. Apoptosis, which represents part of the overall homeostatic process, occurs spontaneously at the stem cell position in the crypts, and very small doses of radiation elevate the levels of apoptosis rapidly in this region. Other cytotoxic agents also target cells in this region including several mutagenic chemicals. Yet other drugs target cells at higher positions in the crypt indicating that all crypt cells possess the programme for apoptosis, but this is normally suppressed in many of the cells. In contrast, high doses of radiation are required to reproductively sterilize the crypts and, using clonal regeneration techniques, the number of clonogenic cells is dependent on the levels of damage induced (dose), i.e. the more injury that is induced the greater number of cells that are recruited into the clonogenic compartment. All doses of radiation trigger rapid changes in proliferation in the stem cell region which suggests that the detection of the induced cell death (even small levels, such as one apoptotic cell per crypt) is efficient and has rapid consequences. p53 may be involved in this damage recognition and apoptosis initiation. The studies to date suggest that apoptosis plays an important role in this tissue in terms of its homeostasis and its protection against carcinogenesis by removal of potentially carcinogenic damaged cells.

Animals↗