bluuebunny/crossref_metadata_2025 huggingface dataset:
Which Tangible and Intangible Assets Matter for Innovation Speed in Start‐Ups?*
Authors: Heirman Ans , Clarysse Bart
Published: June 2007

The launch of the first product is an important event for start‐ups, because it takes the new venture closer to growth, profitability, and financial independence. The new product development (NPD) literature mainly focuses its attention on NPD processes in large firms. In this article insights on the antecedents on innovation speed in large firms are combined with resource‐based theory and insights from the entrepreneurship literature to develop hypotheses concerning the antecedents of innovation speed in start‐ups. In particular, tangible assets such as starting capital and the stage of product development at founding and intangible assets such as team tenure, experience of founders, and collaborations with third parties are considered as important antecedents for innovation speed in start‐ups. A unique data set on research‐based start‐ups (RBSUs) was collected, and event‐history analyses were used to test the hypotheses. The rich qualitative data on the individual companies are used to explain the statistical findings. This article shows that RBSUs differ significantly in their starting conditions. The impact of starting conditions on innovation speed differs between software and other companies. Although intuition suggests that start‐ups that are further in the product development cycle at founding launch their first product faster, our data indicate that software firms starting with a beta version experience slower product launch. The amount of initial financing has no significant effect on innovation speed. Next, it is shown that team tenure and experience of founders leads to faster product launch. Contrary to expectations, alliances with other firms do not significantly affect innovation speed, and collaborations with universities are associated with longer development times.
Development of a Design Audit Tool for SMEs*
Authors: Moultrie James , Clarkson P. John , Probert David
Published: June 2007

There is strong evidence of the importance of good design to company success. However, it is apparent that despite this evidence, design skills are often marginalized in small and medium‐size enterprises (SMEs). This article presents a design audit tool that captures good design principles in a form accessible to industry. Previous audit approaches have focused extensively on the management of new product development (NPD). In this research, the audit tool is based on process maturity principles and explicitly targets the design related activities in NPD—specifically in small firms. The design audit has been developed iteratively by application in action research mode and is supported by evidence from literature and exploratory cases. This inductive development enabled the generation of a robust audit tool through intervention in small firms to improve design practices. The resulting audit tool is designed for use in a multifunctional workshop setting. Typical outputs from application include the generation of action plans for improvement in future performance. This audit tool is based around a model of good design that explicitly distinguishes between management and design related activities in NPD. The audit tool has succeeded in encouraging managers to pay greater attention to the design related elements of NPD. This complements the satisfaction of managerial goals typically emphasized in many NPD processes.
Optimal Cash Tender Offers*
Authors: Schnabel Jacques A. , Roumi Ebrahim
Published: June 2007

This paper develops a contingent claims analysis, a simple decision model for determining the optimal price in a cash tender offer. The implied behavior of the optimal tender offer premium over the market price of the target common stock is also investigated. Those readers interested in applying the model may obtain an interactive computer program written in FORTRAN and implementable on a personal computer from the authors on request.
Solving the Classification Problem in Discriminant Analysis Via Linear and Nonlinear Programming Methods*
Authors: Stam Antonie , Joachimsthaler Erich A.
Published: June 2007

This paper demonstrates the feasibility of applying nonlinear programming methods to solve the classification problem in discriminant analysis. The application represents a useful extension of previously proposed linear programming‐based solutions for discriminant analysis. The analysis of data obtained by conducting a Monte Carlo simulation experiment shows that these new procedures are promising. Future research that should promote application of the proposed methods for solving classification problems in a business decision‐making environment is discussed.
A Simple Heuristic for Lot Sizing with Setup Times
Authors: Trigeiro William W.
Published: June 2007

This paper presents an easily understood and computationally efficient heuristic algorithm for the capacitated lot sizing problem (CLSP), the single machine lot‐sizing problem, with nonstationary costs, demands, and setup times. The algorithm solves problems with setup time or setup cost. A variation of the algorithm can solve problems when limited amounts of costly overtime are allowed.

Results of experimentation indicate that the most significant effects on solution quality are due to the level of setup costs relative to holding costs and the size of the problems as determined by the number of items. Also affecting solution quality are tightness of the capacity constraint and variability of demand in a problem. When the capacity constraint is extremely tightly binding, it sometimes has difficulty finding solutions that do not require overtime.
Decentralization in Linear Programming Models
Authors: Van De Panne C.
Published: June 2007

This paper proposes a decomposition of a linear programming problem based on the structure of the optimal basis matrix. If this matrix contains a zero matrix of appropriate dimensions, the problem may be decomposed into a price‐setting problem and a quantity‐setting problem. This decomposition is valid for a set of coefficients of the problem to be determined by parametric programming. It can be applied to problems with common constraints or common variables. An application to dairy production planning is discussed and a comparison with the Dantzig‐Wolfe decomposition principle is given.
The Performance of MRP Purchase Lot‐Size Procedures Under Actual Multiple Purchase Discount Conditions
Authors: Christoph Orinda Byrd , LaForge R. Lawrence
Published: June 2007

Several heuristic procedures for purchase lot sizing in material requirements planning (MRP) systems were tested with actual data from manufacturing companies. Information provided by the companies for each purchased item included the estimated requirements and costs, the price discount structure from the vendor, and the actual company ordering policy. Simulation tests for each purchased item involved comparisons of several purchase lot‐size procedures from the research literature along with the actual procedure used by the company providing the data. Results indicate that one of the heuristic lot‐size procedures from the literature consistently outperformed the company policies as well as all other models tested. Another noteworthy result is that, in some cases, the actual company order policy was more cost‐effective than some of the models from the research literature.
Data Driven Modeling: An Application in Scheduling
Authors: Franz Lori S.
Published: June 2007

This paper presents a data driven modeling (DDM) approach to certain types of optimization problems. DDM relinquishes control of the completed model to the user department rather than the operations research (OR) staff. The approach emphasizes development of models that are dependent on data maintained and understood by the users. The data base consists of coded user rules which describe when changes will occur in the problem structure and data which captures the generalization of the problem. Both the rules and data can be updated by user department personnel. These data drive a matrix generator controlled by the rules which uses the data base as input to generate the specific model formulation. This DDM system is designed by OR consultants or staff to allow independence of use along with low‐cost and minimal‐effort maintenance. The DDM approach is illustrated with an application to a real‐world medical scheduling problem.
The Representation and Impact of Information System Reliability on Cost Variance Decisions*
Authors: O'Leary Daniel E.
Published: June 2007

Management does not directly observe cost variance processes from the production system; instead, management depends on a report from the cost variance information system as to whether a process is in control or out of control. Unfortunately, cost variance information systems are not always perfectly reliable. Accordingly, this paper extends the cost variance analysis model to include reliability of the cost variance information system. Reliability is introduced by distinguishing between the report from the information system and the actual cost variance.

Although previous cost variance models do not include reliability, management is still likely to be aware of the lack of reliability in cost variance systems. To account for this lack of reliability, management is likely to use any of a number of heuristics. This paper demonstrates that ad hoc heuristics are unlikely to result in the same solutions suggested by the analytic model. In addition, it is shown analytically that not including reliability in cost variance models can lead to examining variances that do not require investigation and not examining variances that do require investigation.
Decision Making, Scaling, and Number Crunching
Authors: Saaty Thomas L.
Published: June 2007

The purpose of this note is to comment on the artificiality of using known scales of measurement (or conveniently improvised numbers) to make decisions. In particular, the pitfalls of trying to please the decision maker and of using normalization as a number crunching tool are discussed. Finally, an example is given to show what is needed to develop a workable and theoretically sound theory for multi‐criteria decisions and to show that the analytic hierarchy process (AHP) meets these demands.
On the Generality of the PERT Average Time Formula
Authors: Troutt Marvin D.
Published: June 2007

It is well known that the PERT average time formula approximation is related to the Beta distribution assumption. In this note, it is shown that if the formula is modified to use the median instead of the mode, then it becomes a good approximation regardless of distribution assumptions. Applications of the formula beyond project management are highlighted.
Noncatheter‐Based Delivery of a Single‐Chamber Lumenless Pacing Lead in Small Children
Authors: KENNY DAMIEN , WALSH KEVIN P.
Published: June 2007

Objectives:

The model 3830 lead (SelectSecure™ Medtronic, Minneapolis, MN, USA) is a bipolar, fixed‐screw, 4.1‐F pacing lead designed for site‐selective pacing. Implantation is usually performed using an 8‐F deflectable catheter system. This catheter is not ideal for smaller children because of both the sheath size and the relatively large deflected curves. We describe a simpler noncatheter‐based delivery system in seven children.

Methods:

A 4.1‐F SelectSecure lead was introduced via a 5‐F SafeSheath (Thomas Medical, Malvern, PA, USA) placed in the left subclavian vein. The SelectSecure lead was passed into the inferior vena cava (IVC) and a loop created, which was then withdrawn into the right atrium. Once in position, the lead was screwed into the myocardium, the SafeSheath was peeled off, and the lead connected to the generator.

Results:

From March 2005 until September 2006, five right atrial leads and two right ventricular leads were implanted in seven patients (six female) with a median weight of 15 kg (8.1–19.4). All leads were successfully placed with excellent pacing thresholds. The median screening time was 7.1 minutes (4.8–11.4) with a median radiation dose of 83 cGy cm2. There were no procedural complications and no lead displacements seen on a median follow‐up of 10 months.

Conclusions:

Delivery of the 4.1‐F SelectSecure pacing lead to the right heart is possible using a noncatheter‐based delivery system. This is effective and safe and does not require the use of a larger delivery system. This allows these thin isodiametric pacing leads to be used advantageously in small children.
End‐of‐life Decisions in ICD Patients with Malignant Tumors
Authors: KOBZA RICHARD , ERNE PAUL
Published: June 2007

Background:

The results of multiple implantable cardioverter‐defibrillator (ICD) studies have demonstrated a survival benefit in specific high‐risk populations, leading to the expansion of ICD implantation rates worldwide. Because the ICD reduces the incidence of sudden cardiac death, patients with these devices more often die of nonarrhythmic causes. For those with a malignancy, little is known about their preferences for disabling ICD therapy.

Methods:

The objective of the present study was to evaluate whether patients with an ICD and a malignant tumor desire deactivation of their ICD in order to have a death without ICD interventions, which are life‐prolonging, bothersome, and prevent a peaceful death. All deceased patients having had an ICD implanted at our institution were retrospectively analyzed with respect to whether the option of disabling ICD therapy had been discussed and whether the ICD had been deactivated.

Results:

Two hundred and seventy‐two patients received an ICD at our institution between January 1, 1994, and January 31, 2007. Thirty‐six of the patients have died, and of these eight had a malignant tumor. In six of these eight patients (75%) the option of disabling their ICD therapy was discussed extensively; none wished to abandon the possibility of terminating a malignant arrhythmia by the ICD.

Conclusions:

With the use of ICDs, patients with heart failure are more frequently protected from arrhythmic death, and consequently treating physicians are increasingly confronted with ICD patients presenting with a malignant tumor or other noncardiac terminal disease. In these situations, dialogue between the treating physician and the patient about the possibility of withdrawing ICD therapy is important to terminal care. The physician must be aware that the patient's attitude may contrast with his/her own, and that the patient may be resolute in maintaining ICD protection from arrhythmic death.
The ICD Shock and Stress Management Program: A Randomized Trial of Psychosocial Treatment to Optimize Quality of Life in ICD Patients
Authors: SEARS SAMUEL F. , SOWELL LAUREN D. VAZQUEZ , KUHL EMILY A. , KOVACS ADRIENNE H. , SERBER EVA R. , HANDBERG EILEEN , KNEIPP SHAWN M. , ZINEH ISSAM , CONTI JAMIE B.
Published: June 2007

Background:

Implantable cardioverter defibrillator (ICD) patients potentially face significant psychological distress because of their risk for life‐threatening arrhythmias and the occurrence of ICD shock.

Methods:

The purpose of this study was to test an ICD stress and shock management program delivered in either a six‐week format or a one‐day workshop format. This intervention was aimed at reducing psychological (anxiety) and physiological (salivary cortisol) markers of distress in ICD patients. Secondary endpoints included measures of quality of life (QOL) and patient acceptance of device therapy, as well as biological mediators of inflammation (TNFα and IL‐6).

Results:

The ICD stress and shock management program resulted in the reduction of anxiety (P < 0.05) and cortisol levels (P < 0.05) in both the six weekly sessions format and the one‐day workshop. Measures of anxiety decreased more rapidly with weekly intervention (P = 0.05). Both formats also resulted in a significant increase in patient acceptance of the ICD (P < 0.01). Follow‐up assessment from posttreatment (T2) to four‐month follow‐up (T4) indicated no significant change in depression scores from posttreatment for all groups taken together, but there was a significant group by time effect, such that the workshop group displayed an increase in depression scores from T2 (M = 8.71, SD = 4.39) to T4 (M = 13.57, SD = 11.90), P < 0.05.

Conclusions:

These results suggest that structured interventions for shocked ICD patients involving ICD education and cognitive‐behavioral strategies can reduce psychological distress and improve quality of life, regardless of format.
Clinical Evaluation of Two Different Evoked Response Sensing Methods for Automatic Capture Detection in the Left Ventricle
Authors: GOETZE STEPHAN , SPERZEL JOHANNES , BIFFI MAURO , SATHAYE ALOK , BROOKE M. JASON , DOELGER ANNETTE , SCHUBERT BERND , BUTTER CHRISTIAN
Published: June 2007

Background:

This acute feasibility study compared two different automatic capture detection methodologies, the reduced coupling capacitor (RCC) and the independent pace/sense (IPS) methods, for the left ventricle (LV).

Methods:

LV threshold tests were performed in DDD mode, with LV‐only and biventricular (BiV) pacing using an external cardiac resynchronization therapy (CRT) defibrillator. Evoked response (ER) signals from LV leads were recorded using the LVTip (LVTip→Can) and LVRing (LVRing→Can) to empty pulse generator (Can) housing sensing vectors to evaluate the two methodologies. Pacing vector, pulse duration, atrioventricular delay, and interventricular delay were varied to assess their effects on ER. The minimum ER amplitude (ERmin), signal‐to‐artifact ratio (SAR), and ER amplitude voltage dependence were evaluated. ERmin>2 mV and SARmin>2 define potential automatic LV capture detection for the two methodologies.

Results:

Data collected from 43 patients (63.7 ± 11.0 years) were analyzed, including unipolar and bipolar (14/29) LV leads. Neither ER sensing method was affected by changing the pacing vector. The LVTip→Can ERmin was significantly decreased at the 1.0‐ms pulse duration when compared to 0.4‐ms (p < 0.05). During BiV pacing, LVTip→Can ERmin increased at negative interventricular delays and decreased at positive interventricular delays relative to simultaneous pacing. LVTip→Can resulted in fewer patients with sufficient ER characteristics for capture detection, albeit only significantly at the extended pulse duration (79% vs 97%, p < 0.05) and at simultaneous and positive interventricular delays (81% vs 97%, p < 0.05).

Conclusions:

Though LV capture detection was feasible using both investigated methods, the RCC method (LVTip→Can) sensitivity to the evaluated pacing parameters suggests the IPS method (LVRing→Can) provides a more robust performance.
Predicting Imminent Episodes of Ventricular Tachyarrhythmia Using Heart Rate
Authors: THONG TRAN , RAITT MERRITT H.
Published: June 2007

Background:A reliable predictor of an imminent episode of ventricular tachyarrhythmia that could be incorporated in an implantable defibrillator capable of preventive therapy would have important clinical utility.

Method:A test set of 208 R–R records saved by defibrillators spanning a mean of 1.6 hours before sustained tachyarrhythmia were used to derive criteria that would improve the specificity of the previously identified monotonic heart rate acceleration predictor. Additional criteria were used, namely two such patterns need to occur within a period of 1.8 hour and the heart rate during these accelerations exceeds 86 bpm (700 ms). The specificity was tested using R–R records matched in duration from 26 control patients with defibrillators during normal periods.

Results:The basic acceleration pattern was found during sinus rhythm in the 1.8‐hour period prior to 83% of episodes of ventricular tachyarrhythmia. It was also found in 43% of the matched set of nonarrhythmic records, corresponding to a specificity of 57%. With the two extra requirement of multiplicity within 1.8 hour and peak heart rate, the sensitivity of the proposed predictor is reduced to 53%, but the specificity is increased to 91%, which corresponds to an average false positive rate of 0.8 event/day across the patient population.

Conclusion:A ventricular tachyarrhythmia predictor based on a pattern of heart rate acceleration has been proposed that can yield sensitivity from 53% to 69%, with specificity up to 91%. Instances of this predictor increase significantly prior to an episode of tachyarrhythmia.
Resolution of T‐Wave Oversensing with Implantable Cardioverter Defibrillator Generator Replacement in an Adolescent
Authors: TUZCU VOLKAN
Published: June 2007

Inappropriate delivery of therapy due to T‐wave oversensing is a frequent complication of intracardiac cardioverter defibrillators (ICD). A 16‐year‐old adolescent with congenital long QT syndrome type 3 underwent single‐chamber implantable cardioverter defibrillator (ICD) (EnTrust VR, Medtronic Inc., Minneapolis, MN, USA) implantation.
He received two appropriate and four inappropriate shocks. The inappropriate shocks were due to T‐wave oversensing. Following the replacement of ICD with a different brand generator (Vitality 2 VR, Boston Scientific Inc., Natick, MA, USA), no more T‐wave oversensing is noted. Proper filtering is imperative in ICDs in order to prevent T‐wave oversensing‐related inappropriate delivery of therapy.
Characterization of Silver Interdiffusion into (Zn,Mg)TiO3+x:Bi:Sb Multilayer Ceramic Capacitor
Authors: Lee Wen‐His , Su Chi‐Yi
Published: June 2007

In this study, (Zn,Mg)TiO3+x+Bi2O3+Sb2O5multilayer ceramic capacitors (MLCCs) with different proportions of a silver (Ag)–palladium (Pd) mixture acting as the inner electrode were sintered at 925°C for 2 h to evaluate the effect of the inner electrode on reliability. The main results reveal that the lifetime is inversely proportional to the Ag content in the Ag/Pd inner electrode. Ag diffusion into the (Zn,Mg)TiO3+x+Bi2O3+Sb2O5MLCC during cofiring at 925°C for 2 h and Ag migration at 140°C against 200 V are both responsible for the short lifetime of the (Zn,Mg)TiO3+x+Bi2O3+Sb2O5MLCC, particularly the latter factor. A Bi,Sb‐rich secondary phase was present at the triple junction and a small amount of Ag was detected from the second phase for a (Zn,Mg)TiO3+x+Bi2O3+Sb2O5MLCC with a high Ag content in the inner electrode of Ag/Pd=99/01. However, this was not the case with a low Ag content in the inner electrode of Ag/Pd=90/10. This means that the Bi,Sb‐rich second phase plays an important role in determining the degradation of insulation resistance due to the excessive formation of oxygen vacancies from the reaction of Ag+for Bi3+or Sb5+substitution to lower the activation energy of the (Zn,Mg)TiO3+Bi2O3+Sb2O5dielectrics and to enhance markedly the effect of Ag migration.
Physical and Mechanical Properties of Bulk Ta4AlC3 Ceramic Prepared by an In Situ Reaction Synthesis/Hot‐Pressing Method
Authors: Hu Chunfeng , Lin Zhijun , He Lingfeng , Bao Yiwang , Wang Jingyang , Li Meishuan , Zhou Yanchun
Published: June 2007

Bulk Ta4AlC3 ceramic was prepared by an in situ reaction synthesis/hot‐pressing method using Ta, Al, and C powders as the starting materials. The lattice parameter and a new set of X‐ray diffraction data were obtained. The physical and mechanical properties of Ta4AlC3 ceramic were investigated. Ta4AlC3 is a good electrical and thermal conductor. The flexural strength and fracture toughness are 372 MPa and 7.7 MPa·m1/2, respectively. Typically, plate‐like layered grains contribute to the damage tolerance of Ta4AlC3. After indentation up to a 200 N load, no obvious degradation of the residual flexural strength of Ta4AlC3 was observed, demonstrating the damage tolerance of this ceramic. Even at above 1200°C in air, Ta4AlC3 still retains a high strength and shows excellent thermal shock resistance, which renders it a promising high‐temperature structural material.
Slurry Consistency and In Situ Synchrotron X‐Ray Diffraction During the Early Hydration of Portland Cements With Calcium Chloride
Authors: Jupe Andrew C. , Wilkinson Angus P. , Luke Karen , Funkhouser Gary P.
Published: June 2007

Class A and H oil well cements are compared at 25° and 50°C with 0%, 1%, 2%, and 4% CaCl2. Up to 4% CaCl2 accelerated Class A thickening, but 4% led to slower thickening than 2% for Class H. C3S hydration in the two cements responded differently to CaCl2. CaCl2 always accelerated aluminate hydration. For Class A, CaCl2 accelerated early Ca(OH)2 precipitation, but sometimes reduced the amount at longer times. This may be coupled to C–S–H gel composition changes. For Class H, Ca(OH)2 precipitation changes nonlinearly with CaCl2 concentration. Ettringite to monosulfate conversion and Friedel's salt formation were sometimes seen.
Temperature‐Stable and Low‐Loss Dielectrics in the Ca(B′1/2Ta1/2)O3 [B′=Lanthanides, Y, and In] System
Authors: Khalam L. Abdul , Thomas Sherin , Sebastian M. T.
Published: June 2007

The Ca(B′1/2Ta1/2)O3 [B′=La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Y, Er, Yb, and In] double perovskite‐type ceramics have been prepared by the conventional solid‐state ceramic route. The phase purity and surface morphology of the sintered ceramics have been studied by X‐ray diffraction (XRD) and scanning electron microscopy methods. XRD study revealed intersubstitution between Ca and B′ ions. Ca(B′1/2Ta1/2)O3 ceramics have relative permittivity (ɛr) in the range 23–30, normalized quality factor (Qu×f) 20 600–59 200 GHz, and temperature coefficient of resonant frequency (τf) −6 to −35 ppm/°C. The dielectric properties of Ca(B′1/2Ta1/2)O3 ceramics have been tailored by the addition of positive τf materials such as CaTiO3, TiO2, Ba(Y1/2Ta1/2)O3, and Ba(Yb1/2Ta1/2)O3, which form a solid solution or a mixture phase with the parent compound. The 0.7Ca(Y1/2Ta1/2)O3–0.3Ba(Y1/2Ta1/2)O3 ceramic has ɛr=27.5, Qu×f=41 900 GHz, and τf=−1.2 ppm/°C, and the 0.6Ca(Yb1/2Ta1/2)O3–0.4Ba(Yb1/2Ta1/2)O3 ceramic has ɛr=27.7, Qu×f=48 000 GHz, and τf=1.8 ppm/°C.
Interface Crystallography and Structure in LaB6–ZrB2 Directionally Solidified Eutectics
Authors: Deng H. , Dickey E. C. , Paderno Y. , Paderno V. , Filippov V.
Published: June 2007

Interfaces in LaB6–ZrB2 composites directionally solidified by a zone melting process were characterized by transmission electron microscopy (TEM). The nominal crystallographic orientation relationship between the two phases corresponded to a high‐symmetry near‐coincidence site lattice (NCSL). The small mistilt (2°–5°) from the high‐symmetry orientation relationship was shown to result in an increased volume density of coincident sites. Furthermore, the dominant interface facet planes were predicted by the NCSL model. The configurations of interfacial misfit dislocations were analyzed by high‐resolution TEM and showed a good agreement with predictions based on the displacement shift complete lattice and secondary original lattice (O2‐lattice) models. These analyses suggested that interfaces were relaxed to relatively low‐energy configurations.
Synthesis and Morphology of TiO2 Nanotube Arrays by Anodic Oxidation Using Modified Glycerol‐Based Electrolytes
Authors: Yin Yuxin , Jin Zhengguo , Hou Feng , Wang Xu
Published: June 2007

Titanium dioxide (TiO2) nanotube arrays were prepared by electrochemical anodization of titanium sheets in the glycerol 176 mL/H2O 44 mL/NH4F 0.5 wt% electrolytes modified with H2SO4 and NaAc addition. The surface morphologies, average inner diameter, and the length of the nanotube arrays changed with the solution pH in the range from 5.6 to 4.0 by adding H2SO4. A uniform surface morphology of the nanotubes with average inner diameter of ∼80 nm and a length of ∼1000 nm was obtained when the solution pH was 5.0. The growth rates of the nanotubes were remarkably enhanced by NaAc addition in the range of 0.04–0.14M. With NaAc addition of 0.10M, the length of the nanotube arrays reached 4.16 μm after an 8‐h anodization, increasing 3.23 μm compared with no NaAc addition. The relationship between solution pH and growth of TiO2 nanotubes was analyzed by current–time curves, solution electrical conductivities, and scanning electron microscopy (SEM), and the role of NaAc was also discussed based on SEM and solution electrical conductivities.
What is the prevalence of various types of prosthetic dental restorations in Europe?
Authors: Zitzmann Nicola Ursula , Hagmann Edgar , Weiger Roland
Published: June 2007

Objectives: The aim of this review was to analyse the prevalence of prosthetic dental restorations in the adult population in Europe and to investigate factors influencing the frequencies of fixed restorations and removable dental prostheses (RDP).

Material and methods: A search for literature up to 31 October 2006 on dental restorations was performed in Medline via PubMed and in an additional hand search using several keywords related to epidemiology and dental restorations. Out of approximately 6000 titles listed, 136 articles were identified, which were related to 13 different European countries. 43 articles fulfilled the inclusion criteria and were included in this review.

Results: Approximately half of the adult population in most European countries have had some type of prosthetic dental restoration. The frequency of RDPs among adults varied between 13 and 29%, with 3–13% edentulous subjects wearing complete dentures in both jaws. The frequency of fixed restorations including crowns and fixed dental prostheses (FDPs, bridges) was the highest in Sweden with 45% and Switzerland (34%). In the recent decades, there has been a slight decrease in RDP use reflecting a decline in edentulism, while more subjects had maintained a residual dentition and were wearing removable partial dentures or fixed restorations. The latter are less prevalent in countries with lower prosperity. If only a few teeth are absent, these are generally replaced with FDPs or have no replacement. If more teeth are missing, the likelihood of a removable restoration increases with the number of teeth to be replaced. A higher frequency of removable restorations is present in older age groups, in subjects living in rural areas, in those from a lower socio‐economic status and in subjects with less education and lower incomes.

Conclusions: All types of fixed and removable restorations are highly prevalent, especially among older age groups, in most European countries. There is a trend towards higher frequencies of fixed restorations, more removable partial dentures and a reduction in complete dentures.
Ante's (1926) law revisited: a systematic review on survival rates and complications of fixed dental prostheses (FDPs) on severely reduced periodontal tissue support
Authors: Lulic Martina , Brägger Urs , Lang Niklaus P. , Zwahlen Marcel , Salvi Giovanni E.
Published: June 2007

Background: In subjects suffering from generalized severe periodontitis, only a few teeth may be treated and used as abutments for fixed dental prostheses (FDPs).

Objective: To systematically review the impact of severely reduced, but healthy periodontal tissue support on the survival rate and complications of FDPs after a mean follow‐up time of at least 5 years.

Search strategy: Publications considered for inclusion were searched in MEDLINE (PubMed) and relevant journals were hand searched. The search was performed in duplicate and was limited to human studies published in the dental literature from 1966 up to and including September 2006. Only publications in English, in peer‐reviewed journals, were considered. Abstracts were excluded.

Selection criteria: Prospective and retrospective cohort studies were included. The primary outcome measure included survival rates of FDPs and abutment teeth, whereas biological and technical complications of FDPs and abutment teeth represented secondary outcome measures.

Data analysis: Summary estimates of survival rates and of biological and technical complications were calculated after 5 and 10 years.

Results: The search provided 860 titles of which six publications were included. A total of 579 FDPs were incorporated and followed up to 25 years. Meta‐analysis yielded an estimated FDP survival rate of 96.4% [95% confidence interval (95% CI): 94.6–97.6%] after five and of 92.9% (95% CI: 89.5–95.3%) after 10 years, respectively. After 10 years, the estimated rate of abutment teeth without endodontic complications amounted to 93% (95% CI: 62.6–98.9%). The 10‐year estimated rate of caries‐free abutment teeth was 98.1% (95% CI: 88.2–99.7%). FDPs without loss of retention were estimated to occur in 95.4% (95% CI: 92.6–97.2%) of cases after 10 years.

Conclusions: These results showed that (i) masticatory function could be established and maintained in subjects receiving FDPs on abutment teeth with severely reduced but healthy periodontal tissue support and (ii) FDPs survival rates compared favourably with those of FDPs incorporated in subjects without severely periodontally compromised dentitions.
Comparison of survival and complication rates of tooth‐supported fixed dental prostheses (FDPs) and implant‐supported FDPs and single crowns (SCs)
Authors: Pjetursson Bjarni E. , Brägger Urs , Lang Niklaus P. , Zwahlen Marcel
Published: June 2007

Objectives: The objective of this systematic review was to assess and compare the 5‐ and 10‐year survival of different types of tooth‐supported and implant‐supported fixed dental prosthesis (FDPs) and single crowns (SCs) and to describe the incidence of biological and technical complications.

Methods: Three electronic searches complemented by manual searching were conducted to identify prospective and retrospective cohort studies on FDPs and SCs with a mean follow‐up time of at least 5 years. Patients had to have been examined clinically at the follow‐up visit. Failure and complication rates were analyzed using random‐effects Poisson's regression models to obtain summary estimates of 5‐ and 10‐year survival proportions.

Results: Meta‐analysis of the included studies indicated an estimated 5‐year survival of conventional tooth‐supported FDPs of 93.8%, cantilever FDPs of 91.4%, solely implant‐supported FDPs of 95.2%, combined tooth‐implant‐supported FDPs of 95.5% and implant‐supported SCs of 94.5%. Moreover, after 10 years of function the estimated survival decreased to 89.2% for conventional FDPs, to 80.3% for cantilever FDPs, to 86.7% for implant‐supported FDPs, to 77.8% for combined tooth‐implant‐supported FDPs and to 89.4% for implant‐supported SCs. Despite high survival rates, 38.7% the patients with implant‐supported FDPs had some complications after the 5‐year observation period. This is compared with 15.7% for conventional FDPs and 20.6% for cantilever FDPs, respectively. For conventional tooth‐supported FDPs, the most frequent complications were biological complications like caries and loss of pulp vitality. Compared with tooth‐supported FDPs, the incidence of technical complications was significantly higher for the implant‐supported reconstructions.The most frequent technical complications were fractures of the veneer material (ceramic fractures or chipping), abutment or screw loosening and loss of retention.

Conclusion: On the basis of the results of the present systematic review, planning of prosthetic rehabilitations should preferentially include conventional end abutment tooth‐supported FDPs, solely implant‐supported FDPs or implant‐supported SCs. Only for reasons of anatomical structures or patient‐centered preferences and as a second option should cantilever tooth‐supported FDPs or FDPs supported by combination of implants and teeth be chosen.
Function. Consensus report of Working Group 3
Authors: Jokstad Asbjørn , Türp Jens C. ,   On behalf of Working Group 3
Published: June 2007

Abstract: The method used by the working group was an iterative process based upon a structured review of the relevant literature by the four author groups. Review papers were circulated to the members of the group before the conference and formed the basis for subsequent discussions. Each paper was subject to detailed collective analysis and subsequently modified on the basis of the panel's discussions and referenced to additional relevant literature where appropriate. The group assessed the levels of evidence for the claims and statements made in the supporting documentation. It was recognized that it was often necessary to adopt a compromise between acceptance of the lowest level, resulting in the largest body of material, and the highest level, which in some cases, produced little evidence. While this approach does not represent endorsement of lower evidence levels per se, it was designed to provide conclusions of clinical utility within the existing knowledge base. The papers, following the scrutiny, were amended and approved by the expert group. The consensus report was prepared by the working group after detailed considerations of the five approved papers.
To what extent does the longevity of fixed dental prostheses depend on the function of the cement? Working Group 4 materials: cementation
Authors: Edelhoff Daniel , Özcan Mutlu
Published: June 2007

Aims/Background: The objective of this review was to define the impact of cementation mode on the longevity of different types of single tooth restorations and fixed dental prostheses (FDP).

Methods: Literature search by PubMed as the major database was used utilizing the terms namely, adhesive techniques, all‐ceramic crowns, cast‐metal, cement, cementation, ceramic inlays, gold inlays, metal‐ceramic, non‐bonded fixed‐partial‐dentures, porcelain veneers, resin‐bonded fixed‐partial‐dentures, porcelain‐fused‐to‐metal, and implant‐supported ‐ restorations together with manual search of non‐indexed literature. Cementation of root canal posts and cores were excluded. Due to lack of randomized prospective clinical studies in some fields of cementation, recommendations had to be based on lower evidence level (Centre of Evidence Based Medicine, Oxford) for special applications of current cements.

Results: One‐hundred‐and‐twenty‐five articles were selected for the review. The primary function of the cementation is to establish reliable retention, a durable seal of the space between the tooth and the restoration, and to provide adequate optical properties. The various types of cements used in dentistry could be mainly divided into two groups: Water‐based cements and polymerizing cements. Water‐based cements exhibited satisfying long‐term clinical performance associated with cast metal (inlays, onlays, partial crowns) as well as single unit metal‐ceramic FDPs and multiple unit FDPs with macroretentive preparation designs and adequate marginal fit. Early short‐term clinical results with high‐strength all‐ceramic restorations luted with water‐based cements are also promising. Current polymerizing cements cover almost all fields of water‐based cements and in addition to that they are mainly indicated for non‐retentive restorations. They are able to seal the tooth completely creating hybrid layer formation. Furthermore, adhesive capabilities of polymerizing cements allowed for bonded restorations, promoting at the same time the preservation of dental tissues.
In patients with temporomandibular disorders, do particular interventions influence oral health‐related quality of life? A qualitative systematic review of the literature
Authors: Türp Jens C. , Motschall Edith , Schindler Hans J. , Heydecke Guido
Published: June 2007

Objectives: The use of patient‐based outcomes to measure therapeutic effectiveness is increasing, because a growing number of clinical scientists are attempting to evaluate the impact of therapy on the recipient. There are indications that patients suffering from temporomandibular disorders (TMDs) may also show a reduced oral health‐related quality of life (OHQoL). It was the purpose of this paper to answer the question as to whether therapeutic interventions in TMD patients have a positive effect on their OHQoL.

Material and methods: A systematic electronic search (Ovid Medline® 1966–2006; Science Citation Index 1945–2006) of the literature was carried out to identify pertinent articles of randomized and non‐randomized clinical trials. Reports on retrospective and prospective studies that specifically focused on OHQoL changes in TMD patients as a consequence of therapeutic interventions were included. The reference lists of the identified articles were screened to find additional pertinent publications.

Results: The investigation yielded seven relevant contributions from Medline®. A quantitative analysis of the seven identified articles was not possible. There was considerable heterogeneity among the investigations with regard to study design, patient characteristics, and provided therapy. Three of the identified articles reported about prospective controlled studies, of which one was an RCT. Four additional investigations were retrospective. According to the results of the only RCT, a 6‐week course of the non‐selective cyclooxygenase (COX) inhibitor naproxen may lead to slightly better OHQoL in patients with temporomandibular joint (TMJ) arthralgia than the selective COX‐2 inhibitor celecoxib. The two other articles reporting of a controlled study showed that selective serotonine uptake inhibitors accompanied by psychological therapy improved OHQoL in individuals with TMJ arthralgia. In contrast, TMJ surgery did not improve OHQoL.

Conclusion: It appears that all therapeutic interventions reported in the identified publications led to at least some improvement of OHQoL. The only exception were patients with multiple TMJ surgeries.
The bases for using a particular occlusal design in tooth and implant‐borne reconstructions and complete dentures
Authors: Klineberg Iven , Kingston Dianna , Murray Greg
Published: June 2007

Objectives: A systematic review identified randomised and other trials (1966–2006) of studies of occlusal design of crowns, complete (CRP) and partial (PRP) removable prostheses and implant‐borne reconstructions, and whether occlusal design influenced diet, quality of life, bruxism and attrition.

Methods: The search primarily included Cochrane Database of Systematic Reviews and Central Register of Controlled Trials, Database of Abstracts of Reviews of Effectiveness, Ovid Medline and PreMedline.

Results: The search yielded 1315 studies: 20 on CRP – 1 RCT, one systematic review, four clinical trials, 10 case series; 22 on PRP – one cohort study, two experimental studies, 15 case reports or case series, three clinical trials; 23 on implant superstructures, and 24 reports on implant failure, 37 on oral health related quality of life, eight on attrition; and four studies on masticatory function.

Conclusions: CRP – Studies of occlusal form and tooth arrangements, included balanced, lingualised and monoplane arrangements – lingualised posterior occlusion was preferred.

Early studies on CRP design were observational as case reports, however data suggested that optimum function is achieved by modification of the maxillary occlusion, irrespective of the opposing mandibular occlusion.

PRP – Edentulous ridge resorption is patient‐specific, has a multifactorial aetiology and there is no objective data to confirm that mechanical factors cause bone loss; oral hygiene management is crucial for long‐term health.

Studies on distal extension PDs confirmed a link between bite force and masticatory function; preservation of two functioning posterior tooth units ipsilateral to the distal extension optimises function. Data indicate that patient‐specific factors, rather than PD design‐specific features, influence long‐term PD outcomes.

Implant superstructures – There is little scientific evidence specifying occlusal and superstructure design for fixed prostheses for teeth or implants. Occlusal scheme design and occlusal form have evolved through clinical experience, but there is no evidence to indicate that a particular design is superior.

Complex neurophysiological mechanisms allow the jaw muscle system to accommodate to oral and dental changes.
Supportive therapy and the longevity of dental implants: a systematic review of the literature
Authors: Hultin Margareta , Komiyama Ai , Klinge Björn
Published: June 2007

Objective: To review systematically whether supportive implant treatment during a follow‐up of at least 10 years after functional loading is effective in prevention of biological complications and fixture loss.

Methods: A MEDLINE search was conducted for the period of 1965 to April 2006 of longitudinal clinical studies with follow‐up periods after implant function of at least 10 years. Sixty‐two studies were initially screened for inclusion and read in full text. Nine studies remained for the final assessment and 53 articles were thus excluded for the following reasons: (1) no information on implant maintenance was presented, (2) the number of patients/implants assessed at 10‐year follow‐up/final evaluation was not presented (3) fixture loss and marginal bone loss during function were not assessed at 10‐year evaluation and (4) residual inflammation and/or probing pocket depth (PPD) not assessed at 10‐year examination.

Results: Fifty‐six percent of 62 initially screened studies did not assess clinical inflammation and PPD around implants at long‐term evaluation of implants. This was the most common reason for exclusion of studies. In 28% of excluded studies, there was no information on implant maintenance during follow‐up. A total of 749 fixtures were included and followed for more than 10 years of functional load. Five of the included studies gave no detailed information of the assessments or the treatment at follow‐up visits during the 10 years. Only in two of the included cohorts were patients enrolled in an individualized supportive program on a 3–6‐month recall interval.

Conclusion: There are, to date, few available studies evaluating the long‐term effect of supportive programs for implant patients. Based on the nine studies included, no evidence is available to suggest the frequency of recall intervals or to propose specific hygiene treatments. There is an urgent need for such studies to be initiated.
What are the prevalence and incidence of tooth loss in the adult and elderly population in Europe?
Authors: Müller Frauke , Naharro Manuel , Carlsson Gunnar E.
Published: June 2007

Objective: The purpose of this review was to study the prevalence and incidence of edentulism and tooth loss in European countries.

Material and method: A literature search was performed by means of Medline/PubMed using various combinations of keywords concerning prevalence and incidence of tooth loss and edentulism, complemented by a hand search. Inclusion criteria were cross‐sectional and longitudinal clinical and questionnaire studies of representative or random samples of ≥100 subjects at the initial examination. Sixty articles were identified; the hand search gave 13 more references.

Results: This literature review demonstrated that there is a lack of epidemiological studies on edentulism and tooth loss in many countries in Europe. The quality of available data varied considerably. There is a documented decline of edentulism with still great differences in prevalence between countries, between geographical regions within countries and between groups with various backgrounds. The mean number of lost teeth increases with age. In several countries many dentate subjects aged 60 years and over still have reduced dentitions possibly needing prosthodontic treatment. The incidence of tooth loss is low but with geographical variation between age groups, and there is a trend for decreasing incidence over the last decades. A great number of variables are associated with tooth loss, and there is no consensus whether dental disease related or socio‐behavioural factors are the most important risk factors. Institutionalised elderly people have, in general, more compromised oral health, including fewer teeth, than those at the same age living freely.

Conclusion: Tooth loss and edentulism are declining at least in those European countries where reliable data are available. However, the WHO goal of retaining at least 20 teeth at the age of 80 years has not yet been met but is being approached in some countries.