Pazopanib pharmacokinetically guided dose optimization in three cancer patients with gastrointestinal resection

PURPOSE

Pazopanib is approved in advanced renal cell carcinoma (RCC) and soft-tissue sarcoma at a flat-fixed dose despite a large pharmacokinetics interindividual variability and a narrow therapeutic index. To our knowledge, pazopanib exposure in patients with gastrointestinal resections (GIR) has not been described. This report focuses on feasibility of pharmacokinetics-guided dose escalation in these patients and clinical implications for their management.

METHOD

A retrospective data collection was performed for three patients with GIR treated with pazopanib, including pazopanib plasma concentrations (high-performance liquid chromatography with UV detection) and treatment adherence (Girerd score).

CASE PRESENTATION

First patient (55-year-old man, RCC, gastric bypass surgery) pazopanib Cmin,ss at day 39 was 4.1 mg/L. Dose escalation to 1800 mg/day fractionated allowed to reach Cmin,ss of 18.5 mg/L (target threshold in RCC patients: 20.5 mg/L). Patient 2 (50-year-old woman, metastatic myxofibrosarcoma, gastric band) showed Cmin,ss of 4.0 mg/L at day 13. In patient 3 (49-year-old man, gastric malignant peripheral nerve sheath tumor, gastrectomy), Cmin,ss at day 13 was 2.7 mg/L. For these two patients, intake with food and dose fractioning only slightly increased pazopanib Cmin,ss to 12.0 mg/L and 6.5 mg/L, respectively (therapeutic threshold in sarcoma patients: 27 mg/L). Treatment adherence was good in all patients.

CONCLUSION

Optimal pazopanib exposure cannot be achieved in patients with GIR, and thus, other therapeutic strategies should be encouraged. Pretherapeutic assessment seems crucial to evaluate factors as bariatric surgery that may impact pazopanib concentrations. Therapeutic drug monitoring could be helpful to optimize pazopanib response in these patients.

Qualitative and quantitative comparison of allergen component-specific to birch and grass analyzed by ImmunoCAP assay and Euroline immunoblot test

Summary

Background.In the diagnostic work up of allergy, determining allergen component-specific immunoglobulin E (IgE) is important for diagnosis, prognosis and choice of treatment. The purpose of this study was to evaluate the performance of the immunoblotting assay (Euroline) in detection of IgE antibodies against timothy grass and birch pollen allergen components compared to fluorescent enzyme assay (ImmunoCAP, Phadia 250). Methods. A total of 128 serum samples from patients allergic to timothy grass and birch pollen were analysed. The levels of IgE antibodies to timothy grass and birch pollen were measured using Euroline DPA-Dx pollen 1 and ImmunoCAP assay. The two methods were then compared on binary (positive vs negative), semi-quantitative (IgE classes) and quantitative (concentration) levels. The two methods were also compared to results from skin prick testing. Results. The Euroline method showed a positive percentage agreement of 93% and negative percentage agreement of 94% with an overall accuracy of 94% when compared to ImmunoCAP. Kappa analysis showed moderate strength of agreement between the methods in determining IgE classes for 7/11 components tested. All components showed a positive correlation when analysed using Spearman's rank correlation. Conclusions. Overall, we found that there is good correlation between the Euroline and ImmunoCAP methods in measuring IgE sensitization.

Optimization of experimental conditions by surface enhanced Raman Scattering (SERS) spectroscopy with gold nanoparticles suspensions

Surface Enhanced Raman Scattering (SERS) spectroscopy is a rapid and innovative analysis technique involving metallic nanoparticles (NPs). The interaction between NPs and norepinephrine gives an exaltation of the Raman signal under certain experimental conditions. The control of the signal exaltation, crucial for sensitive analyses, remains one of the main limitations of this technique. The aim of this work is to optimize the exaltation conditions for an optimal SERS signal at two concentrations of norepinephrine (NOR) and spherical gold NPs in suspension. This first work will fix the optimal experimental conditions essential for the development of robust discriminant and quantitative analysis of catecholamine. Two complete 3-factors 3-levels experiment designs were performed at 20 µg.mL^-1 and 100 µg.mL^-1 norepinephrine concentrations, each experiment being repeated 3 times. The optimization factors were the process of synthesis (variation of the quantity of gold and citrate used for the three synthesis SA, SB and SC) and HCl (0.3 M, 0.5 M, 0.7 M) as well as the volume ratio of NPs and norepinephrine (0.5, 2, 3.5) for SERS acquisition. Spectral acquisitions were performed with a handheld Raman spectrometer with an excitation source at 785 nm. For each sample, 31 acquisitions were realized during 3 s every 8 s. The optimization parameter was the intensity of the characteristic band of norepinephrine at 1280 cm^-1. A total of 5,042 spectra were acquired and the pre-treatment selected for all spectra was asymmetric least square combined to a smoothing of Savistsky Golay (ALS - SG). The optimal contact time between norepinephrine and NPs depends on the experimental conditions and was determined for each experiment according to the mean intensity between the three replicates. After interpretation of the experimental designs, the optimal conditions retained were the quantity of gold corresponding to SA and the HCl concentration 0.7 M for the two concentrations of norepinephrine. Indeed, the optimal volume ratio depend on the NOR concentration.

Discriminative and quantitative analysis of norepinephrine and epinephrine by surface-enhanced Raman spectroscopy with gold nanoparticle suspensions

Surface-enhanced Raman spectroscopy (SERS) is a powerful analytical technique capable of increasing the Raman signal of an analyte using specific nanostructures. The close contact between those nanostructures, usually a suspension of nanoparticles, and the molecule of interest produces an important exaltation of the intensity of the Raman signal. Even if the exaltation leads to an improvement of Raman spectroscopy sensitivity, the complexity of the SERS signal and the numbers of parameters to be controlled allow the use of SERS for detection rather than quantification. The aim of this study was to develop a robust discriminative and quantitative analysis in accordance with pharmaceutical standards. In this present work, we develop a discriminative and quantitative analysis based on the previous optimized parameters obtained by the design of experiments fixed for norepinephrine (NOR) and extended to epinephrine (EPI) which are two neurotransmitters with very similar structures. Studying the short evolution of the Raman signal intensity over time coupled with chemometric tools allowed the identification of outliers and their removal from the data set. The discriminant analysis showed an excellent separation of EPI and NOR. The comparative analysis of the data showed the superiority of the multivariate analysis after logarithmic transformation. The quantitative analysis allowed the development of robust quantification models from several gold nanoparticle batches with limits of quantification of 32 µg/mL for NOR and below 20 µg/mL for EPI even though no Raman signal is observable for such concentrations. This study improves SERS analysis over ultrasensitive detection for discrimination and quantification using a handheld Raman spectrometer.

Effectiveness of a 'do not interrupt' vest intervention to reduce medication errors during medication administration: a multicenter cluster randomized controlled trial

Background

The use of a ‘do not interrupt’ vest during medication administration rounds is recommended but there have been no controlled randomized studies to evaluate its impact on reducing administration errors. We aimed to evaluate the impact of wearing such a vest on reducing such errors. The secondary objectives were to evaluate the types and potential clinical impact of errors, the association between errors and several risk factors (such as interruptions), and nurses’ experiences.

Methods

This was a multicenter, cluster, controlled, randomized study (March–July 2017) in 29 adult units (4 hospitals). Data were collected by direct observation by trained observers. All nurses from selected units were informed. A ‘Do not interrupt’ vest was implemented in all units of the experimental group. A poster was placed at the entrance of these units to inform patients and relatives. The main outcome was the administration error rate (number of Opportunities for Error (OE), calculated as one or more errors divided by the Total Opportunities for Error (TOE) and multiplied by 100).

Results

We enrolled 178 nurses and 1346 patients during 383 medication rounds in 14 units in the experimental group and 15 units in the control group. During the intervention period, the administration error rates were 7.09% (188 OE with at least one error/2653 TOE) for the experimental group and 6.23% (210 OE with at least one error/3373 TOE) for the control group (p = 0.192). Identified risk factors (patient age, nurses’ experience, nurses’ workload, unit exposition, and interruption) were not associated with the error rate. The main error type observed for both groups was wrong dosage-form. Most errors had no clinical impact for the patient and the interruption rates were 15.04% for the experimental group and 20.75% for the control group.

Conclusions

The intervention vest had no impact on medication administration error or interruption rates. Further studies need to be performed taking into consideration the limitations of our study and other risk factors associated with other interventions, such as nurse’s training and/or a barcode system.

Trial registration

The PERMIS study protocol (V2–1, 11/04/2017) was approved by institutional review boards and ethics committees (CPP Ile de France number 2016-A00211–50, CNIL 21/03/2017, CCTIRS 11/04/2016). It is registered at ClinicalTrials.gov (registration number: NCT03062852, date of first registration: 23/02/2017).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12912-021-00671-7.

Pre-treatment allergen-specific IgE analysis and outcomes of allergen immunotherapy

Summary

Background. Patients show varied results to allergen immunotherapy (AIT. The reason for this variability is unclear. Objective. To describe the relationship between AIT efficacy and demographic characteristics, as well as pre-treatment plasma levels of specific IgE-antibodies to grass and birch pollen. Methods. A retrospective study was performed based on medical records of 128 patients who received AIT. The patients completed a questionnaire and pre-AIT plasma levels of allergen-specific IgE to grass and birch pollen were measured using EUROLINE DPA-Dx pollen 1 method. Results. Seventy percent of patients classified their allergic symptoms as less severe after AIT. Twenty-seven percent had received AIT targeting only grass pollen, 19% targeting only birch pollen, and 55% targeting both grass and birch. A total of 35 different IgE profiles were found across our study population. On comparison of the demographic characteristics and concentration of allergen-specific IgE-antibodies, no statistically significant differences could be found.Conclusions. The majority of patients rated their allergic symptoms as less severe after AIT. No clear relationship could be demonstrated between pre-treatment allergen-specific IgE concentration, or demographic characteristics, and effect of AIT. There may be other factors underlying the different responses to AIT.

[Subcontracting a steam sterilization activity: Impact on surgical instruments]

Subcontracting our institution's sterilization activity induced the implementation of an automated cleaning facility. Following this development, some of the resterilizable stainless steel needle holders started to show abnormal corrosion. Our study goal was to investigate the causes of this corrosion in order to optimize the sterilization circuit. A full sterilization process mapping and Ishikawa diagram enabled us to identify potential causes of corrosion. The needle holders' intrinsic characteristics, like steel quality and manufacturing, were analyzed as well as extrinsic factors such as the influence of preprocessing soaking conditions, steel passivation, water quality and the impact of corrosion inhibitors. Each potential factor of corrosion was tested in real conditions on needle holders' kits. The needle holders steel grade complies with medical standards and the tests showed that passivation and pre-processing conditions were not involved in the occurrence of corrosion, contrary to soaking length and use of softened rinsing water, containing more chloride than reverse osmosis water, and, thus conducive to rust formation. Moreover, corrosion inhibitors were deemed ineffective or incompatible. Due to this analysis, the incidence of corrosion was reduced by switching softened water to osmosis water and by introducing dynamic drying in the automated cleaning process. In addition, this work stresses the importance of minimizing waiting times and auditing the sterilization circuit before any subcontracting. Management Guidelines related to sterilization's outsourcing would probably have helped to limit this episode.

Discriminative and Quantitative Analysis of Antineoplastic Taxane Drugs Using a Handheld Raman Spectrometer

This study was conducted to evaluate the ability of Raman spectroscopy (RS) to control antineoplastic preparations used for chemotherapy in order to ensure its physical and chemical qualities. Three taxane drugs: cabazitaxel (CBX), docetaxel (DCX) and paclitaxel (PCX) at therapeutic concentration ranges were analyzed using a handheld spectrometer at 785 nm. Qualitative and quantitative models were developed and optimized using a calibration set (n=75 per drug) by partial least square discriminant analysis and regression and validated using a test set (n=27 per drug). All samples were correctly assigned with an accuracy of 100%. Despite optimization, quantitative analysis showed limited performances at the lowest concentrations. The root mean square error of predictions ranged from 0.012 mg/mL for CBX to 0.048 mg/mL for DCX with a minimal coefficient of determination of 0.9598. The linearity range was validated from 0.175 to 0.30 mg/mL for CBX, from 0.40 to 1.00 mg/mL for DCX and from 0.57 to 1.20 mg/mL for PCX. Despite some limitations, this study confirms the potential of RS to control these drugs and also provides substantial advantages to secure the activity for healthcare workers. As a result of its rapidity and the uncomplicated use of a handheld instrument, RS appears to be a promising method to augment security of the medication preparation process in hospitals.

Rapid discrimination and quantification analysis of five antineoplastic drugs in aqueous solutions using Raman spectroscopy

The aim of this study was to assess the ability of Raman spectroscopy to discriminate and quantify five antineoplastic drugs in an aqueous matrix at low concentrations before patient administration. Five antineoplastic drugs were studied at therapeutic concentrations in aqueous 0.9% sodium chloride: 5-fluorouracil (5FU), gemcitabine (GEM), cyclophophamide (CYCLO), ifosfamide (IFOS) and doxorubicin (DOXO). All samples were packaged in glass vials and analyzed using Raman spectrometry from 400 to 4000cm^-1. Discriminant analyses were performed using Partial Least Squares Discriminant Analysis (PLS-DA) and quantitative analyses using PLS regression. The best discrimination model was obtained using hierarchical PLS-DA models including three successive models for concentrations higher than the lower limit of quantification (0% of fitting and cross-validation error rate with an excellent accuracy of 100%). According to these hierarchical discriminative models, 90.8% (n=433) of external validation samples were correctly predicted, 2.5% (n=12) were misclassified and 6.7% (n=32) of the external validation set were not assigned. The quantitative analysis was characterized by the RMSEP that ranged from 0.23mg/mL for DOXO to 3.05mg/mL for 5FU. The determination coefficient (R²) was higher than 0.9994 for all drugs evaluated except for 5FU (R²=0.9986). This study provides additional information about the potential value of Raman spectroscopy for real-time quality control of cytotoxic drugs in hospitals. In some situations, this technique therefore constitutes a powerful alternative to usual methods with ultraviolet (UV) detection to ensure the correct drug and the correct dose in solutions before administration to patients and to limit exposure of healthcare workers during the analytical control process.

Continuous ventilation during intubation through a supraglottic airway device guided by fiberoptic bronchoscopy: a observational assessment

INTRODUCTION

supraglottic airway devices remain, despite advances in video laryngoscopy, important tools in the management of unexpected difficult airways. Intubation through a functioning supraglottic airway device with the aid of a fiberoptic bronchoscope is a well-known technique usually performed in apnoea. With a simple modification, the patient can be ventilated during this procedure.

METHODS

In this observational study, Tracheal intubation Assisted by Bronchoscopy And Sad during Continuous Oxygenation (TABASCO) was performed as part of department training routine in 26 elective, fasted patients. A supraglottic airway device was used as a conduit for an endotracheal tube.

RESULTS

All patients were easily intubated and ventilation was maintained during the procedure. The gap between the outer diameter of the fiberoptic bronchoscope and the inner diameter of the endotracheal tube was more than 2 mm in 25 of 26 patients. Effective ventilation was confirmed by clinical signs, capnography and pressure-volume curves. No signs of airtrapping occurred.

DISCUSSION

No adverse events were observed during this form of airway management in this small series of elective and fasted patient when performed by an anaesthesiologist experienced in fiberoptic intubation. A gap between fiberoptic bronchoscope and endotracheal tube inner lumen seems to be prerequisite for easy ventilation through the supraglottic airway. In trained hands, this technique can be a means to secure an airway with an intubating bronchoscope without pausing ventilations. A prerequisite for this is a well-functioning supraglottic airway device.

Voriconazole pharmacokinetic variability in cystic fibrosis lung transplant patients

BACKGROUND

Aspergillosis is a high-risk complication in cystic fibrosis (CF) lung transplant patients. Azole antifungal drugs inhibit CYP3A4, resulting in significant metabolic drug-drug interactions. Voriconazole (VRZ) was marketed without therapeutic drug monitoring (TDM) recommendations, consistent with favorable pharmacokinetics, but regular determinations of plasma VRZ concentration were introduced in our center to manage interactions with calcineurin inhibitors and to document the achievement of therapeutic levels.

METHODS

VRZ TDM data analysis for trough concentration (C0) and peak concentration (C2) was carried out, using validated liquid chromatography assay with ultraviolet detection, for 35 CF lung transplant patients (mean age 25 years, mean weight 47 kg, balanced sex ratio) since 2003. Therapeutic range (C0: 1.5 +/- 0.5 - C2 : 4.0 +/- 1.0 mg/L) was expressed relative to pivotal pharmacokinetic trial data.

RESULTS

The duration of VRZ treatment ranged from 9 days to 22 months. The recommended standard dose of VRZ (200 mg twice a day, following the loading dose) resulted in significant plasma concentrations (>0.5 mg/L) in 20% of CF lung transplant patients. Therapeutic concentrations were obtained using higher doses (average 570 +/- 160 mg/day, +43%, P<0.01). Despite adaptation, C0 remained <0.5 mg/L (11%), even when the drug was administered intravenously, highlighting the variability of VRZ pharmacokinetics, possibly enhanced by CYP2C19 polymorphism. The risk of inefficacy during periods of underdosage was overcome by treatment with antifungal drug combinations (caspofungin, n=10). The therapeutic index was limited by neurologic effects (14%) and hepatic abnormalities (30%). VRZ concentrations correlated significantly (P<0.01) with aspartate aminotransferase levels but not with bilirubin levels. VRZ acted as a metabolic inhibitor of tacrolimus (C0 to dose ratio 5.8 +/- 2.6, n=31/VRZ versus 1.7 +/- 0.9 alone, P<0.001). Large changes in azole concentration affected the magnitude of the drug-drug interactions and adjustment requirements.

CONCLUSIONS

TDM is required because VRZ levels are often undetectable in treated CF lung transplant patients, supporting the use of antifungal drug combinations until achievement of VRZ C0 at a steady state between 1 and 2 mg/L. Plasma VRZ concentrations should be determined for the quantitative, individualized management of drug-drug interactions in lung transplant patients, in particular immunosuppressant such as tacrolimus, considering VRZ to be both a target and an inhibitor of CYP3A4.

Determination of rpoA as the most suitable internal control to study stress response in C. jejuni by RT-qPCR and application to oxidative stress

Campylobacter jejuni represents one of the major causes of bacterial enteritis caused by food in humans. There are still mechanisms to be deciphered to better understand better its physiology and pathogenesis. Study of gene expression levels by RT-qPCR could be used, but to be accurate and reproducible, a good internal control has to be chosen. The aim of this study was to identify a highly stable housekeeping gene in Campylobacter jejuni that could constitute a good internal control to study gene expression variations between different growth phases or stress conditions. Expression levels of six different housekeeping genes (gyrA, ilvC, rpoA, slyD, thiC and rrs) were measured by RT-qPCR under different conditions (exponential phase, stationary phase, cold shock, cold shock+oxidative stress, oxidative stress). The rpoA gene was chosen as the best internal control. In a previous study, 9 proteins were identified as involved in oxidative stress response, among which 3 virulence factors. Expression levels of genes coding for these proteins was evaluated by RT-qPCR using rpoA as an internal control. The results obtained were concordant with what had been observed at the proteomic level, validating the methods used and confirming the hypothesis of a potential link between oxidative stress and virulence factors expression.

Concentrations of cat (Fel d1), dog (Can f1) and mite (Der f1 and Der p1) allergens in the clothing and school environment of Swedish schoolchildren with and without pets at home

To investigate whether our hypothesis that cat and dog owners bring allergens to public areas in their clothes was true or not, we studied the levels of Fel d1, Can f1, Der p1 and Der f1 in dust from the clothes and classrooms of children in a Swedish school. We also investigated the levels of allergen in different areas in the four classrooms used by the children. Thirty-one children were selected in four classes, forming three groups: cat owners, dog owners and children without a cat or dog at home. Furthermore, a group of children with asthma was included. Cat and dog allergens were detected in all 57 samples from clothes and classrooms. Mite allergen Der f1 was detected in low concentrations in 6 out of 48 and Der p1 in 5 out of 46 samples investigated. The concentrations of Can f1 were higher than those of Fel d1 in samples from clothes (geometric mean: 2676 ng/g fine dust and 444 ng/g) and classrooms (Can f1: 1092 ng/g, Fel d1: 240 ng/g). The dog owners had significantly higher concentrations of Can f1 (8434 ng/g fine dust) in their clothes than cat owners (1629 ng/g, p < 0.01), children without cat or dog (2742 ng/g, p < 0.05) and children with asthma (1518 ng/g, p < 0001). The cat owners did not have significantly higher levels of Fel d1 (1105 ng/g) in their clothes compared to the other three groups. (D: 247 ng/g, nCnD: 418 ng/g) but the levels were significantly higher than for all children without a cat at home (345 ng/g, p < 0.05). No concentrations of mite allergen and low concentrations of Fel d1 and Can f1 were found in the children's hair. There were significantly higher concentrations of Fel d1 and Can f1 in dust from curtains than in samples from floors and bookshelves (p < 0.05). There was no significant difference between the allergen concentrations in samples from curtains and from desks and chairs, including the teachers' chairs, the only upholstered furniture in the rooms. Our results support the hypothesis that cat and dog owners bring allergens to public areas in their clothes and support other studies showing that textiles and upholstered furniture function as reservoirs of cat and dog allergens. Thus, children with asthma and other allergic diseases will be exposed to cat and dog allergens at school and by contact with pet owners, even if they avoid animal allergens at home.

Re-examination of incisal tooth wear in children and adolescents

The material presented in this report was derived from a longitudinal study of the development and progress of incisal tooth wear in children and adolescents. The study group was established in 1991-1992 (baseline examination) and consisted of participants between 8 and 15 years of age. They were re-examined in 1993 (interim examination) and in 1994 (final examination). In all, 77 school children (30 females and 47 males) participated in the three examinations. The timespan between baseline and interim was on average 15 months and the period between interim and final examination averaged 16 months. The total observation period was approximately 32 months. Assessments of incisal wear was made on stone casts using the incisal wear index which was shown to have good reproducibility. The results demonstrated that the prevalence and severity of incisal wear had increased significantly with age. In general the rate of incisal wear progression was higher between baseline and interim than between interim and final examination. In this respect certain differences between the tooth types seemed to exist. At baseline the relationship between age and incisal wear was positive and statistically significant for all tooth types. At the final examination the strength of this relationship had decreased for maxillary and mandibular central and lateral incisors. For canine teeth of both jaws the relationship between age and incisal wear was no longer statistically significant at the final examination.

Relationship between incisal tooth wear and the increasing number of permanent teeth in children and adolescents

The material presented in this report was derived from a longitudinal study of the development and progress of incisal tooth wear in children and adolescents. The study group was established in 1991/1992 and consisted of 77 participants between 8 and 15 years old. All participants were re-examined in 1994. The interval between the first and second examination was approximately 32 months. Each participant was scored for tooth wear of the anterior teeth of both jaws according to the Incisal wear Index (IwI) and the number of permanent teeth and the tooth types present were recorded at each examination. The results showed that the pattern of incisal wear had been maintained during the observation period. Severity of incisal wear increased as the number of teeth increased. The strength of the relationship between incisal wear and the number of teeth decreased during the observation period. At the same time, the number of teeth and the size of the wear increments were negatively correlated indicating that the rate of wear progression decreased as the number of teeth increased.

Relationship between alignment conditions of teeth in anterior segments and incisal wear

This report describes the alignment condition and incisal wear of the anterior teeth in individuals 16-19 years of age. Tooth alignment and incisal wear were assessed on casts in accordance with two index systems NONAT (non-aligned tooth) and IwI (incisal wear index). Tests of the methods showed that the reproducibility of the assessments of tooth alignment and incisal wear were satisfactory. The results of the study of tooth irregularity demonstrated that the prevalence of non-alignment of one or more of the anterior teeth were much the same (approximately 50%) for the maxillary and mandibular jaws. The highest frequency was found for the maxillary lateral incisors and the mandibular central incisors (approximately 45%). A relationship between the alignment conditions and incisal wear of the anterior teeth was established. It appeared that non-alignment of one or more teeth in one or both jaws was associated with less severe incisal wear of the anterior teeth. This was most pronounced for non-aligned maxillary central incisors and non-aligned mandibular central incisors.

A 2-year follow-up study of incisal tooth wear in dental students

This report was derived from cross-sectional and longitudinal analyses of prevalence, pattern, and severity of incisal wear in 64 dental students who had virtually complete dentitions at the first examination and unchanged dentitions at the re-examination. They were first examined in 1991 and re-examined after 24 months in 1993. The average age of the students in 1991 was 23 +/- 1.7 years. Assessment of incisal wear was made on stone casts based on silicone impression material in accordance with the Incisal wear Index (IwI). The results showed that the prevalence of incisal wear had not changed during the observation period. The severity of incisal wear for maxillary and mandibular central and lateral incisors had remained essentially the same, whereas the severity of wear of maxillary and mandibular canines had increased during the observation period. There was no statistically significant relationship between age and IwI. The wear pattern found for anterior teeth is discussed in relation to the cuspid protection and the group function theories of occlusion.

Longitudinal study of incisal tooth wear in children and adolescents

This report was derived from a longitudinal study of the development and progress of incisal tooth wear in children and adolescents. The study group was established in 1991/1992 and consisted of 79 participants between 8 and 15 yr. They were reexamined in 1993 and the time span between the first and second examination was 12-14 months. Assessment of incisal wear was made on stone casts based on silicone impression material according to the Incisal wear Index (IwI). The index used was shown to have good reproducibility. The results showed that the pattern of incisal wear had been maintained during the observation period. Prevalence and severity of incisal wear had increased significantly with age. The strength of the suggested linear relationship between age and incisal wear decreased during the observation period. At the same time the growth increments of wear, delta IwI, were negatively correlated with age, indicating that the progression of incisal wear slowed down with increasing age. Description of the true relationship between age and incisal wear outside the age range represented in the sample must await the results of forthcoming studies.

Prevalence, pattern, and severity of incisal wear in dental students

This paper describes the prevalence, pattern, and severity of incisal wear of anterior teeth in 64 dental students at an average age of 23 +/- 1.7 years with a high number of permanent teeth present. The index used to assess wear on stone casts (IwI) was shown to have good reproducibility. The results indicated that about 98% of the anterior teeth had been worn to various degrees. In both jaws central incisors were most commonly affected by incisal wear, canines followed next in order, and lateral incisors were least commonly affected. Wear of identical teeth on the right and left side tended to be bilaterally symmetrical in both jaws. The results of these initial observations suggest that data from re-examination of this study group will lend themselves to detecting possible changes of the pattern and severity of incisal wear of permanent anterior teeth.

Adaptation of resin facings to cast gold alloy restorations in the mouth

The occurrence of marginal spaces between the resin facing and gold alloy framework in 176 crowns and bridge retainers was studied. The restorations were made for canine teeth. The assessment of spaces at the cervical alloy-resin junction was carried out by examining slides of the buccal surfaces taken after application of disclosing agent. Spaces at the incisal alloy-resin junction were assessed by examining resin models under the stereomicroscope. Randomly selected restorations were grouped and examined with reference to length of clinical service (1, 3, 6, and 9 years). The methods were tested for reliability and consistency. The results showed that the frequency of cervical spaces tended to increase with length of clinical service, whereas the frequency of the incisal spaces seemed to remain unchanged. The most severely worn facings had the highest frequency of cervical spaces. In contrast, the least worn facings seemed to have the highest frequency of incisal spaces. For both the cervical and the incisal spaces the highest frequencies were found for relatively long resin facings.

The pattern and severity of wear of resin facings in fixed prosthetic restorations in vivo

Wear of prosthodontic resin facings in 176 metal-resin canine crowns and retainers for fixed partial dentures was studied in clinical photographs and assessed using a graded scale. Four cross-sectional groups of restorations were studied according to length of clinical service (1, 3, 6, and 9 years). The criteria used during the examination described loss of substance in relationship to the metal cast framework. The method was tested for reliability and consistency. The results showed that the extent of wear increased with increasing time of clinical service (P less than .05). More severe wear scores were assigned to restorations in female patients than to those in male patients (P less than .05), to the mandibular facings compared to those in the maxillae (P less than .05), and the incisal areas of the facings compared to the cervical areas (P less than .05). Patients instructed in oral hygiene measures tended to show more severe wear than noninstructed individuals. A significant association was established between the ratio of vertical and horizontal overlap and the wear scores. Increasing VO/HO ratios seemed to be accompanied by increasing wear.

Dental practitioners' evaluation of the metal-resin and metal-ceramic technique in the treatment with fixed prosthetic restorations

To collect information on the use of the metal-resin and the metal-ceramic technique, a questionnaire survey among general practitioners was carried out in Bergen, Norway. Of the 20 dentists (16% sample) randomly selected among the private general practitioners, 17 (85%) responded. The results indicated that 45% metal-resin and 55% metal-ceramic constructions were inserted. Metal-ceramic crowns were selected for their favorable esthetics, whereas metal-resin appliances were preferred because of their repair possibilities and good marginal adaptation. Most dentists (70%) claimed that metal-resin restorations have a better marginal adaptation than metal-ceramic constructions. Location in the mouth, the general periodontal condition, and evidence of wear in the remaining dentition also appeared to influence the selection of the type of tooth-colored veneered crown.

Fixed restorations produced for recipients of dental prosthodontic treatment. A comparison between general dental practice and a dental school

Fixed prosthodontic work ordered by general dental practitioners was examined through registrations made in commercial dental laboratories. A comparison was made with similar data from student files on fixed prosthodontic treatment at the University Clinic in Bergen, Norway, which is located in the same geographic area. The results indicated that the distributional pattern of fixed restorations within the dentition was much the same in the individuals attending the general dental practitioners as in those treated at the dental school. While the practicing dentists preferred metal-ceramics in most cases, most of the restorations inserted at the dental school were based on the metal-resin technique.

Changes over time in the clientele and restoration pattern in a dental school prosthodontic department

The clientele and the production of single artificial crowns and fixed partial dentures in the Department of Prosthodontics were compared from 1964/68-1982/87. In the first period 65 per cent of the single crowns were made for women versus 55 per cent in the second. In the first period 69 per cent of the crowns were placed in the upper jaw as against 60 per cent in the second period. On average 1.6 crowns were made per female patient in the first period versus 1.4 per male patient. In the second period both sexes averaged 1.8 units. In both jaws the percentage of root-filled crowned teeth had increased in the second period to 60 per cent from 48 per cent in the upper jaw and 46 per cent in the lower jaw. In both sexes maxillary and mandibular teeth were crowned on average 13 years later in the second period than in the first. Sixty per cent of the fixed partial dentures were made for women in the first period versus 55 per cent in the second. In the first period 74 per cent of the bridges were made for the upper jaw as against 70 per cent in the second period. The mean pontic to abutment ratio was 0.7 in both periods. The maximum number of bridges in the first period were made for patients 40-59 years of age versus 50-69 years in the second period.(ABSTRACT TRUNCATED AT 250 WORDS)

Flexural strength of a high-temperature soldered cobalt-chromium alloy

The flexural strength of a high-temperature soldered cobalt-chromium alloy was compared with that of the intact alloy. In one test group the specimens were soldered by Vitallium welding rods and in the other group Bego cobalt-chromium solder was used. The cylindrical portion of all specimens was mounted equally in an Instron testing machine. No statistically significant differences were found in flexural strength between the groups.

Properties of prosthetic resin-veneer materials processed in commercial laboratories

Seventeen dental technicians heat-cured microfilled resins, and light-cured hybrid and microfilled resins were used. Marginal adaptation, porosity, hardness, and indentation creep were determined. The results demonstrated considerable variations in all properties studied. The most pronounced variations within the individual brands were found for the properties of porosity and marginal adaptation. When the different products studied were compared, in general the most substantial variations were found for the light-cured specimens. The extremes of number of pores per mm2 were 1.52 and 10.46 for one light-cured product. A moderate scattering of the results of hardness and creep was found. The highly-filled light-cured brands obtained the highest hardness numbers (VHN) and the lowest creep values compared with those of the heat-cured resins. The uneven technical quality found may in part explain the clinical failures of resin facings which are occasionally observed.

Porosity of resin veneer materials

The present investigation has studied the effects of different types of resins and different processing and curing methods on the number and size of pores occurring in resin facing materials. The mean number of pores per square millimeter varied between 0.5 and 4. The highest numbers occurred in unfilled heat-polymerized acrylic resin and in light-activated resin, whereas the lowest numbers were found in heat-polymerized micro-filled resin. Specimens processed in accordance with the free technique and cured under pressure consistently obtained lower numbers of pores than the corresponding specimens processed in a flask. Most of the pores were less than 50 micron diameter in all test groups. From a clinical point of view, a dense resin with a limited content of pores may give the most favorable results in terms of mechanical, esthetic, and hygienic properties of the veneer.

Marginal adaptation of resin veneers to gold castings

The magnitude of the fissures between resin facing materials and gold castings was measured by light microscopy. Two different products and two different processing procedures were used. The effect of water sorption on the fissure size was also studied. Mean fissure sizes varied between 3 and 25 microns. The best adaptation between the resin material and the gold alloy was obtained by the conventional closed flasking technique compared with free processing in a pressure vessel. When processed by closed flasking the product that did not contain microfiller showed fissure widths approximately one fourth of those resulting from the open processing technique. The other product, containing microfiller, was less sensitive with regard to processing. The effect of water sorption on the fissure width was most evident in the test groups containing specimens processed in flask.

Liberation of copper, zinc, and cadmium from different amalgams

Release of copper, zinc, and cadmium from six different amalgams in 0.9% NaCl solution has been registered during a 4-week period. The products showed widely different corrosion behavior. A dispersion-type amalgam released the smallest amounts of copper but the largest amounts of zinc. A product containing indium had a high rate of copper dissolution. Cadmium was liberated to a great extent from a copper amalgam. The rate of corrosion varied greatly for the different products during the time of the experiment. The liberation of copper and zinc was inversely correlated.

Bending strength of intact and repaired denture base resins

Results of bending strength and deflection at fracture of intact and repaired denture base resin specimens were obtained. Both heat-cured and cold-cured resins of two different products were used. After storage in distilled water at 37 degrees C for 1 month, some of the intact heat-cured specimens were dried in air at 21 +/- 1 degree C for 24 h before testing. This induced a lowering of the bending strength. There was no difference in strength between the two products. However, the intact heat-cured specimens of SR 3/60 showed higher results of deflection at fracture than Vertex. Repaired specimens had a bending strength between 42.9% and 61.2% compared with the intact heat-cured specimens tested immediately after storage in water. The repair performed with the low-viscosity self-cured resin resulted in higher bending strength values than when using repair material with the higher initial viscosity. Drying the broken heat-cured specimens for 24 h at 21 +/- 1 degree C before the repair and painting with monomer liquid on the fractured surfaces of the heat-cured resin was without effect on the bending strength of the repaired specimens.

Corrosion of silver soldered orthodontic wires

The amounts of metals liberated from silver soldered stainless steel and cobalt-chromium orthodontic wires were measured. Measurements were taken after 3 days and 24 days immersion in 0.9% sodium chloride solution. High amounts of copper and zinc and some cadmium from the silver solder were found. The silver soldered stainless steel wire corroded more than the cobalt-chromium type, and liberated more nickel and chromium than did the cobalt-chromium wires.

Flexural strength of joined and intact amalgam

Flexural strength of joined and intact specimens of five different alloys were measured. The same alloys were also tested in compression. Joined specimens were also tested in compression. Joined specimens were made by condensing fresh amalgam against the ground surface of 1 week old amalgams. Joined specimens had a flexural strength between 11.5% and 51.4% compared to the intact specimens. The high copper alloys obtained the lowest values for fracture toughness and plastic strain when tested in compression. A positive correlation was shown between flexural strength of joined specimens and plastic strain and between flexural strength of intact specimens and fracture toughness.