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At least 343 records · Page 19Linked to original sources
PubMed2001

Comparison of photo-activation versus chemical or dual-curing of resin-based luting cements regarding flexural strength, modulus and surface hardness.

This study investigated the efficiency of chemical activation of dual-cure resin-based luting cements as compared with light- and dual-curing. Curing was performed by (i) mixing base and catalyst without subsequent irradiation (chemical curing=CC), (ii) mixing base and catalyst with direct irradiation (dual-cure=DC) or with (iii) irradiation through 2.5 mm of leucite-reinforced glass-ceramics (IPS Empress, Ivoclar) (dual-cure through porcelain=DCtP), (iv) using only the base paste with direct irradiation (light-curing=LC) or with (v) irradiation through porcelain (light-curing through porcelain=LCtP). Specimens of four fine-hybrid DC resin composites and one self-cure hybrid resin composite (only CC) were prepared and tested after 24 h for flexural strength, modulus of elasticity (ISO 4049) and surface hardness (Vickers). For all materials and parameters, dual-curing produced higher values than LC, even when irradiation was performed through porcelain. Following self-curing without photo-activation, flexural strength was 68.9-85.9%, the modulus 59.2-94.5% and Vickers hardness 86.1-101.4% of the corresponding values obtained by dual-curing with direct irradiation. Light-curing through porcelain as compared with direct irradiation reduced the values for most parameters and materials. In contrast, dual-curing maintained flexural strength for all, the modulus for three and the hardness for one of the materials. The mechanical properties of the self-curing resin cement ranged between those of the DC materials.

Aluminum Silicates↗
PubMed2002

A histomorphometric analysis on bone dynamics in denture supporting tissue under continuous pressure.

The purpose of this study was to investigate bone dynamics under a denture base, in relation to the intensity of continuous pressure exerted through it to the denture supporting tissue. Two hundred and fifty male rats of Wistar strain were divided into five groups, four of which wore experimental dentures to load continuous pressure of 0.0, 1.0, 10.0 or 20.0 kPa to the molar region of the hard palate. The fifth group was the non-denture-wearing group. Fluorescent labelled palatal bone tissue was stained with Villanueva bone stain and was prepared for the undecalcified grinding section. In the 0.0 kPa group whose mucosa was covered with denture base, although no bone resorption was observed, bone formation was inhibited up to 4 weeks after the denture insertion. Bone dynamics in the 1.0 kPa group was similar to those in the 0.0 kPa group. In the 10.0 and 20.0 kPa groups, bone resorption was observed until 3 and 2 weeks after the denture insertion, and the amount of bone resorption (AoBR) was 24 +/- 17 and 35 +/- 21 lm, respectively. After bone resorption in these groups, although osteoid formation increased earlier than 0.0 kPa group, mineralization showed a similar time course with 0.0 kPa group. In conclusion, bone dynamics under a denture base caused by continuous pressure exerted through it was revealed to show a time course depending on the intensity of the initial pressure. Amount of bone resorption was also revealed to correspond to the intensity of the initial pressure. Bone formation following bone resorption did not cause equivalent recovery of the bone surface level to the level observed in the case without bone resorption.

Acrylic Resins↗
PubMed2002

Vascular endothelial growth factor in minor salivary glands: effect of ageing.

Morphological and physiological age changes are described in human salivary glands. Vascular endothelial growth factor (VEGF) is neoangiogenic growth factor found in normal salivary glands. Considering the neoangiogenic properties of VEGF and its important function in inflammation, repair and, probably, in oral mucosa homeostasis, the purpose of the present study was to evaluate the effect of ageing on the immunolocalization of VEGF in minor salivary glands. Paraffin-embedded tissue blocks containing normal labial salivary glands were retrieved and classified according to the patients' age in two groups (< 20 and > 40-year-old). The biotin-streptavidin-peroxidase system was used to detect the VEGF antigen. The results demonstrated that the mean level of VEGF immunoreaction in the young group was not statistically different from the old group when compared by the Mann-Whitney U-test (P = 0.54). This may indicate that although salivary flow reduction may develop in old patients, some properties of the salivary glands may not be affected.

Adolescent↗
PubMed2002

Changes in occlusal force and occlusal contact area after active orthodontic treatment: a pilot study using pressure-sensitive sheets.

The aim of this study was to investigate functional changes in occlusion during retention. Data on occlusal force (OcFr) and occlusal contact area (OcAr) was obtained using the pressure-sensitive sheet, from a treated group (20 female patients) who had had four premolar extractions and treatment with standard edgewise appliances, and a control sample who matched the treated group of retainer for sex, age and Angle classification at 1 year after removal. A repeated measures analysis of variance showed that the mean values of total OcFr and OcAr in the treatment group gradually increased during retention and were 669.3 N and 15.1 mm2, respectively, at 1 year after removal of retainer. The increases of OcFr and OcAr were larger in the molar region, especially at the second molar. At 1 year after removal of retainer, OcFr and OcAr in the second molar were significantly larger in the treatment group than in the control sample, and a similar distribution pattern of OcFr and OcAr to those in normal occlusion was seen. These results suggested that balanced OcFr and OcAr might be obtained during and after retention, due to the settling of molars that had been discluded by active orthodontic treatment.

Adolescent↗
PubMed2002

Accuracy of check-bite registration and centric condylar position.

In a dentate subject a jaw relation can either be determined in maximum intercuspation and is as such given by the occlusal morphology, or the mandibular position can be allocated according to the centric position of the condyles. For comprehensive restorative treatment or analytic measures of the occlusion it is important to record the centric condylar position. Various registration methods have been described in the literature, but there is no consensus on which is the 'best'. The aim of the present study was therefore to assess the accuracy of various registration methods and evaluate a possible influence of the used materials. Four dentists were involved in the clinical part of the study, another was responsible for the measurements. Impressions were taken from 81 fully dentate volunteers. The casts were mounted by face-bow transfer and central-bearing-point (CBP) registration into Dentatus articulators. Subsequently the centric condylar position was determined with six different methods and materials, respectively. Each method was reproduced twice so that a total of 18 registrations was performed per patient. The mandibular positions which resulted from the individual registrations were then repeatedly compared in the condylar area using a computer supported specially modified measuring articulator. The accuracy was found best for the unrefined wax wafer registration (x=0.33 mm) and with an average of 0.44 mm worst when using acrylic wafers. The CBP and frontal jig methods as well as tin-foil and refined wax wafers showed an accuracy in-between these boundaries. The biggest measured mandibular displacement between any two registrations were considerably 2.0 mm. However, the described differences in accuracy between the various methods and materials proved statistically not significant. All investigated jaw registrations showed an accuracy of about 20 times the tactile fine sensibility of natural teeth which has to be taken into account when inserting fixed prosthetic restorations in centric condylar position. Despite meticulous clinical and technical procedures small occlusal adjustments are therefore almost unavoidable.

Acrylic Resins↗
PubMed2002

Voluntary and reflex control of the human temporalis muscle.

Electromyographic recordings (EMGs) were made in 10 human subjects from the anterior and posterior parts of the temporalis muscle using skin surface electrodes. The activities produced by voluntary maximal clenching tasks and the reflex responses to electrical stimulation of the muco-gingival junction were studied. In most subjects, maximum activity in both parts of the muscle occurred when clenching in the intercuspal position (anterior temporalis: 7 of 10 subjects; posterior temporalis: 9 of 10 subjects). Clenching maximally in the retruded position usually resulted in less activity; when this activity was expressed as a percentage of the maximum achieved by each subject for that part of the muscle, the median values were: anterior temporalis, 68% and posterior temporalis, 79%. Clenching in the protruded position produced little or no activity (median values: anterior temporalis, 3%; posterior temporalis, 5%). There were no significant differences between the EMG activities of the anterior and posterior parts of the muscle during these tasks when the activities were normalized to the maximum achieved in each part of the muscle. Application of electrical stimuli at the muco-gingival junction (upper incisor region) produced reflex inhibitions and excitations in both parts of the muscle. There were no significant differences in the thresholds of these reflexes between the anterior and posterior parts of the muscle. Furthermore, there was little difference between the two parts of the muscle in terms of the latencies, durations and magnitudes of the responses. Thus the results of the study suggest that there are similar neural control mechanisms for the anterior and posterior parts of the temporalis muscle despite the common view that these parts of the muscle have different functions.

Adult↗
PubMed1997

Meta-analysis of randomized control trials addressing brief interventions in heavy alcohol drinkers.

OBJECTIVE: To assess the effectiveness of brief interventions in heavy drinkers by analyzing the outcome data and methodologic quality. DESIGN: (1) Qualitative analysis of randomized control trials (RCTs) using criteria from Chalmers' scoring system; (2) calculating and combining odds ratios (ORs) of RCTs using the One-Step (Peto) and the Mantel-Haenszel methods. STUDY SELECTION AND ANALYSIS: A MEDLINE and PsycLIT search identified RCTs testing brief interventions in heavy alcohol drinkers. Brief interventions were less than 1 hour and incorporated simple motivational counseling techniques much like outpatient smoking cessation programs. By a single-reviewer, nonblinded format, eligible studies were selected for adult subjects, sample sizes greater than 30, a randomized control design, and incorporation of brief alcohol interventions. Methodologic quality was assessed using an established scoring system developed by Chalmers and colleagues. Outcome data were combined by the One-Step (Peto) method; confidence limits and chi 2 test for heterogeneity were calculated. RESULTS: Twelve RCTs met all inclusion criteria, with an average quality score of 0.49 + or - 0.17. This was comparable to published average scores in other areas of research (0.42 + or - 0.16). Outcome data from RCTs were pooled, and a combined OR was close to 2 (1.91; 95% confidence interval 1.61-2.27) in favor of brief alcohol interventions over no intervention. This was consistent across gender, intensity of intervention, type of clinical setting, and higher-quality clinical trials. CONCLUSIONS: Heavy drinkers who received a brief intervention were twice as likely to moderate their drinking 6 to 12 months after an intervention when compared with heavy drinkers who received no intervention. Brief intervention is a low-cost, effective preventive measure for heavy drinkers in outpatient settings.

Adult↗
PubMed2003

Have the results of randomized clinical trials of pacing altered the practice of cardiac pacing?

Randomized clinical trials are the gold standard for the evaluation of new therapies. However, in the early years of pacing, the observational benefits were so great and the lifesaving benefits to patients so readily obvious that randomized trials were not necessary to prove benefit. As the technology has matured, advances have become more evolutionary than revolutionary, and observational analyses are unable to provide convincing evidence of small-to-moderate benefits. Thus, randomized trials of sufficient sample size are necessary to reliably assess the small-to-moderate effects of advances such as dual-chamber pacing, rate modulation, and mode switching. It is only during the last decade, however, that the evidence base for pacing with regard to randomized trials has begun to emerge. It is unclear whether the emerging results of these clinical trials have affected the clinical practice of pacing.

Arrhythmias, Cardiac↗
PubMed2002

The relationship between left ventricular shape and QT interval dispersion.

Left ventricular geometry is suspected to affect heterogeneity of myocardial repolarization; therefore, it is plausible but unproven that increased sphericity of the left ventricle is associated with greater QT interval dispersion. In 60 patients with dilated cardiomyopathy with left ventricular ejection fraction < or = 30%, we found that spherical distortion of the left ventricle was associated with increased QT dispersion, implying increased heterogeneity of myocardial repolarization.

Aged↗
PubMed2001

Left ventricular early diastolic inflow velocity and atrial ventricular plane downward velocity: useful parameters to test diastolic function in clinical practice? Diastolic parameters tested in a clinical setting.

AIMS: To study the clinical value of the colour-M-mode slope of the early diastolic left ventricular filling phase (Vp) and the early diastolic downward M-mode slope of the left atrioventricular plane displacement (EDS), compared with diastolic function assessed by traditional Doppler evaluation. METHODS AND RESULTS: In 65 consecutive patients EDS and Vp were compared with a four-degree traditional diastolic function classification, based on pulsed Doppler assessment of the early to atrial transmitral flow ratio (E/A), the E-wave deceleration time (Edt), and the systolic to diastolic (S/D) pulmonary venous inflow ratio. Vp (P=0.006) and EDS (P=0.045) were related to traditional diastolic function (Kruskal--Wallis analysis). EDS showed a trend brake between the moderate and severe diastolic dysfunction groups by traditional Doppler evaluation. Vp and EDS correlated weakly in simple linear regression analysis (r=0.33). Vp and EDS discriminated poorly between normal and highly abnormal diastolic function. CONCLUSIONS: Vp and EDS were significantly related to diastolic function by traditional Doppler evaluation. They were, however, not useful as single parameters of left ventricular diastolic function due to a small difference between normal and highly abnormal values, allowing for little between-measurement variability. Consequently, these methods for the evaluation of left ventricular diastolic function do not add significantly to traditional Doppler evaluation.

Adult↗
PubMed1996

Therapeutics and inflammatory bowel disease: a guide to the interpretation of randomized controlled trials.

Randomized controlled trials are the optimal means of assessing the efficacy of new treatments. This report reviews the methodology of clinical trials in inflammatory bowel disease using examples from recent randomized trials of therapy for Crohn's disease and other gastrointestinal diseases to show key principles. Guidelines for the practicing clinician to evaluate these studies are provided.

Guidelines as Topic↗
PubMed2001

Outcomes of open versus closed treatment of mandibular subcondylar fractures.

OBJECTIVES: The purpose of this study was to compare the long-term treatment results of open reduction and rigid internal fixation (ORIF) with closed reduction and maxillomandibular fixation (CRMMF) for subcondylar fractures when guided by specific indications and contraindications. PATIENTS AND METHODS: A protocol for the treatment of condylar process fractures was developed that included absolute and relative indications and contraindications as well as a technique regimen. To evaluate the results of this protocol, 10 patients treated with CRMMF and 10 treated by ORIF were recalled after a minimum of 6 months and examined for gender, race, diagnosis, age at injury, time since operation, and cause of the fracture. Each group was assessed by 2 blinded investigators for maximum interincisal opening, right lateral excursion, left lateral excursion, protrusive movement, deviation on opening, scar perception, motor function, sensory perception, contour perception, occlusion, and perception of pain. Nonparametric data were compared for statistical significance with a chi-square analysis and parametric data with an independent samples t-test (P < .05). RESULTS: No statistically significant differences existed between the ORIF and CRMMF groups for gender, race, diagnosis, or cause. Moreover, no differences existed for age at injury, maximum interincisal opening, right lateral excursion, left lateral excursion, protrusive movement, deviation on opening, or occlusion. Differences were noted between groups for time since operation, scar perception, and perception of pain. Using the protocol outlined, there were no differences between the ORIF and CRMMF groups for ranges of motion, occlusion, contour, and motor or sensory function. The ORIF group was associated with perceptible scars. The CRMMF group was associated with chronic pain. CONCLUSIONS: Using a treatment protocol, there were few differences in outcomes between patients treated with CRMMF and ORIF for subcondylar fractures.

Adult↗
PubMed2001

The changing face of odontogenic infections.

PURPOSE: The purpose of this investigation was to compare characteristics of patients hospitalized with odontogenic infections during the 1980s to those of the 1990s. PATIENTS AND METHODS: This study was a retrospective record review that compared 2 cohorts of patients admitted to the same institution during two 81-month periods, one decade apart. Admission criteria were face or neck swelling suggesting abscess or cellulitis and one or more of the following: temperature above 38 degrees C, white blood cell (WBC) count greater than 10.8 x 10(3)/microL, or concern about airway compromise. Characteristics reviewed were age, gender, race, admission temperature, admission WBC count, fascial space(s) involved, tooth of etiology, duration of hospitalization, and bacteria isolated. Data were compared for statistical significance (P <.05). RESULTS: No significant differences were found between the 2 cohorts for age, gender, race, admission temperature, admission WBC count, space involvement, or length of stay (P <.05). One tooth (mandibular left first molar) of 52 was involved more frequently in the 1990 group (P <.03). Gram-positive cocci were isolated significantly more frequently from the 1990s patients than from the 1980s patients (P <.03). There were also significant differences (P <.02) between cohorts in the isolation frequency of individual genera, such as alpha-hemolytic Streptococci, coagulase negative staphylococci, Staphylococcus epidermidis, Bacteroides melanogenicus, beta-lactamase positive Bacteroides, Eikenella corrodens, and Neisseria species. Eighty-one percent of the bacteria cultured from the 1990s patients were resistant to one or more common antibiotics; 47% of these organisms were Staphylococcus aureus. CONCLUSION: No clinically significant differences existed in the characteristics of patients hospitalized with odontogenic infections between the 1980s and the 1990s. Although there were differences in the type and prevalence of bacteria isolated, this was probably a result of changes in nomenclature, identification protocols, and isolation techniques.

Abscess↗
PubMed2001

Discectomy as an effective treatment for painful temporomandibular joint internal derangement: a 5-year clinical and radiographic follow-up.

PURPOSE: The purpose of this prospective study was to compare the preoperative and 5-year postoperative status of patients after unilateral discectomy for painful internal derangement of the temporomandibular joint. PATIENTS AND METHODS: The study was based on 64 patients. Fifty-six had disc displacement without reduction and 8 had disc displacement with reduction. The patients were examined clinically and radiographically before and 5 years after the operation according to a standardized protocol. RESULTS: Eighty-five percent of the patients (n = 52) had good results, 6% had acceptable results, and 9% had a poor outcome. Three patients (5%) were reoperated and 5 other patients (8%) needed a contralateral operation during the 5-year follow-up. The median increase in maximum mouth opening was 11 mm (range, -8 to +35 mm) and 83% of the patients had more than 40 mm maximal mouth opening postoperatively. Seventy-five percent of the patients had crepitation at 5-year follow-up compared with 27% before the operation. Postoperatively, the majority of the joints showed radiographic evidence of osteophytes, flattening, and sclerosis. The radiographic alterations did not correlate with the patients' symptoms. CONCLUSIONS: The results of this long-term follow-up after unilateral discectomy support the use of this operation in patients with painful internal derangement who show no improvement after prior nonsurgical treatment. The postoperative radiographic alterations should be interpreted as adaptive changes rather than progressive degenerative joint disease.

Adolescent↗
PubMed2002

Biomarkers predictive of lymph node metastases in oral squamous cell carcinoma.

PURPOSE: The ability of oral squamous cell carcinoma to metastasize to lymph nodes does not always show a relationship with clinical staging. The aim of this study was to attempt to define a trend for predictive histopathologic and/or molecular biomarkers in the development of nodal metastasis by analyzing 2 clinically extreme groups. PATIENTS AND METHODS: Patients with small primary tumors (T1, T2) with lymph node metastasis and patients with large primary tumors (T3, T4) without metastatic disease were identified among 315 consecutive cases of primary oral squamous cell carcinoma. Group comparisons were made with use of a Mann-Whitney test, and associations among the variables were assessed with nonparametric and parametric correlational analyses. RESULTS: The degree of keratinization was significantly less in primary tumors with lymph node metastasis (P < or = .01). The degree of keratinization was significantly associated with nuclear pleomorphism (P =.02), number of mitoses (P =.02), stage of invasion (P =.002), and p53 expression (P =.04), independent of clinical stage of the tumor. Other microscopic features and immunohistochemical markers did not differ significantly between the groups (P >.05). CONCLUSION: These data indicate that there still is no single predictive parameter superior to the degree of keratinization to identify patients at risk for the development of regional metastasis.

Adult↗
PubMed2003

Discectomy of the temporomandibular joint: 3-year follow-up as a predictor of the 10-year outcome.

PURPOSE: The study goal was to evaluate whether the 3-year follow-up evaluation of temporomandibular joint (TMJ) discectomy in a consecutive series of patients with TMJ internal derangement was a reliable predictor for the 10-year outcome of the operation. MATERIAL AND METHODS: Twenty-nine patients with TMJ internal derangement were treated with discectomies, 6 bilaterally and 23 unilaterally. The patients were followed up for 10 years. RESULTS: The dropout rate was zero at the 3-year follow-up, and 5 patients (17.2%) had dropped out at the 10-year follow-up. There was a significant reduction in the median visual analog scale recordings, and all but 1 patient reported reduction in the pain score. Mandibular motion increased significantly after 3 years, and similar or improved recordings were made at the 10-year follow-up. All but 5 patients showed an increased motion at the 10-year follow-up compared with the preoperative motion. The only complication seen at the 10-year follow-up examination was a slight anesthesia of the auriculotemporal nerve in 1 patient. All types of additional therapy decreased significantly after the operations. CONCLUSIONS: Discectomy of the TMJ may significantly reduce pain and improve function in patients with internal derangement on a long-term basis. The 3-year follow-up examination proved to be a reliable predictor of the 10-year results.

Adolescent↗
PubMed2001

An investigation of psychological distress in patients who have been treated for head and neck cancer.

There is now ample evidence that psychological distress is common in patients with head and neck cancer and that psychology has a role in reducing this distress. In this study, the prevalence, nature, and correlates of distress were investigated, in 18 patients who were no longer being actively treated but were attending a follow-up clinic or support group (n= 9 each). Four of the patients had appreciable psychological distress and four each had anxiety or depression of at least borderline importance. The degree of depression and distress decreased with increasing age and there were trends for depression to decrease with time after the onset of the illness and to be slightly less common among those attending the support group (2/9 compared to 4/9). Numerous psychosocial difficulties were reported and perceptions of support available from friends and family were mixed. There are implications for services, and in particular, patients need to be given clear information about the resources available to give them psychosocial support.

Adult↗
PubMed2001

Aprotinin reduces blood loss and the need for transfusion in orthognathic surgery.

A randomized, placebo-controlled, double-blind trial (n= 15 in each group) showed that patients given aprotinin intravenously (200 ml, [2000000 kallikrein inactivator units] before the operation and then 50 ml per h until the end of the operation) during simultaneous maxillary Le Fort 1 and mandibular sagittal split osteotomies, lost 52% less blood than controls (calculated by subtracting the volume of saline irrigant used from the volume of blood collected in the aspirator bottle and surgical drains). Patients given aprotinin lost a mean (SD) of 473 (190) ml compared with 986 (356) ml in controls. They also required significantly less transfused blood (1 was given 2 units in the aprotinin group compared with 9 given a mean of 1.5 units (range 1-4) in the control group). There were no complications attributable to this drug.

Adult↗