Distinguishing skill levels with haptic simulation in restorative dentistry: Myth or reality?

INTRODUCTION: This study aims to validate that haptic simulator assistance could distinguish skill levels with haptic simulation in restorative dentistry. MATERIALS AND METHODS: This work was carried out with 93 first-year, 87 third-year and 44 fifth-year dental students. The promotions of first- and fifth-year dental students made one session to represent the negative and the positive controls, respectively. The third-year dental students were the studied population. Whatever the group, the maximum time for each reparation was restricted to 3 min. All students have to perform the same three exercises. The third-year dental students performed four sessions spread over the whole university year. For each test, the total score provided by the simulator was recorded and analysed. RESULTS: The exercises are not discriminating in direct vision while the exercise in indirect vision is very interesting to distinguish the levels of the learners. CONCLUSION: The results underline that the exercises in indirect vision could distinguish different profiles of student having different preclinical and clinical levels, while making it possible to follow the acquisition of clinical competence.

Ethical issues in managing the COVID-19 pandemic.

The COVID-19 pandemic has had an immense and worldwide impact. In light of future pandemics or subsequent waves of COVID-19 it is crucial to focus on the ethical issues that were and still are raised in this COVID-19 crisis. In this paper, we look at issues that are raised in the testing and tracing of patients with COVID-19. We do this by highlighting and expanding on an approach suggested by Fineberg that could serve as a public health approach. In this way, we highlight several ethical issues. As regards testing, questions are raised such as whether it is ethical to use less reliable tests in order to increase testing capacity or minimize harm for patients. Another issue is how wide testing should be and whether selective testing is in accordance with principles of social justice. Patients who have recovered from COVID-19 might have some degree of immunity but attributing certain 'immunopriviliges' raises ethical questions. The use of various tracing methodologies (mobile apps or databases and trained tracers) raised evident questions of social justice and privacy. We argue why it is key to always uphold a test of proportionality where a fair balance must be sought.

Challenges in turning a great idea into great health policy: the case of integrated care.

BACKGROUND: In the organization of health care and health care systems, there is an increasing trend towards integrated care. Policy-makers from different countries are creating policies intended to promote cooperation and collaboration between health care providers, while facilitating the integration of different health care services. Hopes are high, as such collaboration and integration of care are believed to save resources and improve quality. However, policy-makers are likely to encounter various challenges and limitations when attempting to turn these great ideas into effective policies. In this paper, we look into these challenges. MAIN BODY: We argue that the organization of health care and integrated care is of public concern, and should thus be of crucial interest to policy-makers. We highlight three challenges or limitations likely to be encountered by policy-makers in integrated care. These are: (1) conceptual challenges; (2) empirical/methodological challenges; and (3) resource challenges. We will argue that it is still unclear what integrated care means and how we should measure it. 'Integrated care' is a single label that can refer to a great number of different processes. It can describe the integration of care for individual patients, the integration of services aimed at particular patient groups or particular conditions, or it can refer to institution-wide collaborations between different health care providers. We subsequently argue that health reform inevitably possesses a political context that should be taken into account. We also show how evidence supporting integrated care may not guarantee success in every context. Finally, we will discuss how promoting collaboration and integration might actually demand more resources. In the final section, we look at three different paradigmatic examples of integrated care policy: Norway, the UK's NHS, and Belgium. CONCLUSIONS: There seems widespread agreement that collaboration and integration are the way forward for health care and health care systems. Nevertheless, we argue that policy-makers should remain careful; they should carefully consider what they hope to achieve, the amount of resources they are willing to invest, and how they will evaluate the success of their policy.

Methodological Approach to the Endodontic Treatment of First Premolars with Three Root Canals: Two Case Reports.

AIM: The aim of this article was to promote a methodology in the endodontic management of complex premolars with multiple root canals Background: The success of endodontic treatment depends on a meticulous clinical and radiographic analysis, the creation of a suitable access cavity and chemical and mechanical preparation, followed by three-dimensional filling of the entire root canal system. Consequently, it is essential to look for the presence of additional root canals to prevent endodontic treatment failure Case description: Two cases are presented. The first case concerned a 50-year-old male patient of North African origin who consulted in the context of a global prosthetic restoration including endodontic treatment of the maxillary left first premolar (tooth no. 24). The second case concerned a 29-year-old male patient of North African origin who was referred to us by his primary care practitioner in an urgent context of pain and infection present for two weeks (tooth no. 44). In both cases, it was the in-depth radiographic analysis, combined with manual exploration under the surgical micro- scope, that led to the relatively rare identification of a third root canal. Shaping, disinfection and three-dimensional filling of the entire root canal system were then performed in accordance with widely validated protocols. CONCLUSION: The maxillary and mandibular premolars, due to their highly variable root canal system configuration and a number of root canals and roots, appear to be teeth for which treatment is potentially complex. The acuteness of digital-tactile sense and the advent of 3D imaging and optical aids optimize the treatment of all the root canals of a tooth Clinical significance: These case reports demonstrate the importance of clinical and radiographic inspections to guide practitioners in the search for additional root canals in premolars and promote a methodological approach.

The patient perspective in health care networks.

BACKGROUND: Health care organization is entering a new age. Focus is increasingly shifting from individual health care institutions to interorganizational collaboration and health care networks. Much hope is set on such networks which have been argued to improve economic efficiency and quality of care. However, this does not automatically mean they are always ethically justified. A relevant question that remains is what ethical obligations or duties one can ascribe to these networks especially because networks involve many risks. Due to their often amorphous and complex structure, collective responsibility and accountability may increase while individual responsibility goes down. MAIN BODY: We argue that a business ethics approach to ethical obligations for health care networks, is problematic and we propose to opt for a patient perspective. Using the classic four principles of biomedical ethics (justice, nonmaleficence, beneficence and autonomy) it is possible to identify specific ethical duties. Based on the principle of justice, health care networks have an ethical duty to provide just and fair access for all patients and to be transparent to patients about how access is regulated. The principle of nonmaleficence implies an obligation to guarantee patient safety, whereas the principle of beneficence implies an obligation for health care networks to guarantee continuity of care in all its dimensions. Finally, the principle of autonomy is translated into a specific obligation to promote and respect patient choice. Networks that fail to meet any of these conditions are suspect and cannot be justified ethically. CONCLUSIONS: Faced with daunting challenges, the health care system is changing rapidly. Currently many hopes ride on integrated care and broad health care networks. Such networks are the topic of empirical debate, but more attention should be given to the ethical aspects. Health care networks raise new and pressing ethical issues and we are in need of a framework for assessing how and when such networks are justified.

In Defence of Moral Pluralism and Compromise in Health Care Networks.

The organisation of health care is rapidly changing. There is a trend to move away from individual health care institutions towards transmural integrated care and interorganizational collaboration in networks. However, within such collaboration and network there is often likely to be a pluralism of values as different health care institutions often have very different values. For this paper, we examine three different models of how we believe institutions can come to collaborate in networks, and thus reap the potential benefits of such collaboration, despite having different moral beliefs or values. A first way is the pragmatic way in which the different health care institutions avoid ethical reflection and focus on solutions. A second possible route is that of consensus where health care institutions base their collaboration on values that they all share. The third, and final, approach is that of compromise. Although moral compromise is often seen in a negative light, we argue that in many cases compromise might be necessary and ethically justified. In a final section, we will shift our focus from discussing various theoretical methods to allow collaboration to the potential content of consensus or compromise.

The role of hospitals in bridging the care continuum: a systematic review of coordination of care and follow-up for adults with chronic conditions.

BACKGROUND: Multiple studies have investigated the outcome of integrated care programs for chronically ill patients. However, few studies have addressed the specific role hospitals can play in the downstream collaboration for chronic disease management. Our objective here is to provide a comprehensive overview of the role of the hospitals by synthesizing the advantages and disadvantages of hospital interference in the chronic discourse for chronically ill patients found in published empirical studies. METHOD: Systematic literature review. Two reviewers independently investigated relevant studies using a standardized search strategy. RESULTS: Thirty-two articles were included in the systematic review. Overall, the quality of the included studies is high. Four important themes were identified: the impact of transitional care interventions initiated from the hospital's side, the role of specialized care settings, the comparison of inpatient and outpatient care, and the effect of chronic care coordination on the experience of patients. CONCLUSION: Our results show that hospitals can play an important role in transitional care interventions and the coordination of chronic care with better outcomes for the patients by taking a leading role in integrated care programs. Above that, the patient experiences are positively influenced by the coordinating role of a specialist. Specialized care settings, as components of the hospital, facilitate the coordination of the care processes. In the future, specialized care centers and primary care could play a more extensive role in care for chronic patients by collaborating.

Porosity of flowable resin composites is not influenced by applicator tip diameter.

PURPOSE: To assess the influence of applicator tip diameter on the inclusion of porosities in three different flowable resin composites. METHODS: The initial porosity of three syringes [Filtek Supreme XTE Flowable (XTE), Grandio Flow (GRF), Gradia Direct Flo (GDF)] was determined by 3D tomography. 25 samples per syringe, i.e. 75 samples in total, were prepared using five applicator tips of different diameters (n= 5). The porosity of the 75 samples was assessed by 3D tomography. RESULTS: For each of the materials, the applicator tips, irrespective of type, all generated an increase in the average porosity percentage compared to the initial porosity of the syringes. For XTE and GRF, the applicator tips, irrespective of type, all generated a decrease in the average porosity volume compared to the initial average porosity volume in their respective syringes. Conversely, for GDF the average porosity volume of the samples was increased. Furthermore, for each of the materials, varying the diameter of the applicator tips had no significant influence on the porosity percentage and volume. Using the present study conditions, the applicator tip generated a variation in the initial porosity of the materials; however, the diameter of the tip had no influence on said variation. CLINICAL SIGNIFICANCE: It appears that practitioners can choose an applicator tip with a diameter that best suits the size and shape of the cavity to be filled using a syringe of flowable resin composite without this having any impact on the percentage and volume of porosities in the final filling of the cavity.

The ethical and clinical importance of measuring consciousness in continuously sedated patients.

Continuous sedation at the end of life is a practice that has attracted a great deal of attention. An increasing number of guidelines on the proposed correct performance of the practice have been drafted. All of the guidelines stress the importance of using sedation in proportion to the severity of the patient's symptoms, thus to reduce the patient's consciousness no more than is absolutely necessary. As different patients can have different experiences of suffering, the amount of suffering should, ideally, be assessed subjectively; that is, via communication with the patient. Continuously sedated patients are often unable to communicate, however, making subjective methods of pain assessment unusable. For these patients, the degree of consciousness is the sole available measure. It therefore seems important to adequately measure how deeply the patient is sedated, thereby allowing sedation to be increased when it is too light and decreased when it is too heavy. This is in accordance with the idea that reducing consciousness is not an ethically neutral act. Although consciousness measuring techniques are a hot topic in anesthesiology, almost no research exists on the use of such techniques in the context of continuous sedation at the end of life. This article aims to review existing techniques to measure consciousness and to evaluate their applicability, efficiency, and invasiveness for patients who are continuously sedated until death. Techniques commonly used to assess the depth of sedation in continuously sedated patients are basic clinical assessment and sedation scales, as they are often considered reliable and non-invasive. These techniques might not be very reliable, however, since it is known that some patients are nonresponsive and yet aware. Moreover, sedation scales require stimulation of the patient (for example prodding, shaking, or providing painful stimuli), and can thus be considered invasive of one's bodily integrity or dignity. Other techniques, such as EEG (electroencephalography) derivatives, may score better on reliability and invasiveness. Yet these have so far never been compared to sedation scale scores for patients receiving continuous sedation at the end of life. Therefore, we conclude that, for both clinical and ethical reasons, research into the efficiency and applicability of other techniques, such as derivatives of EEG, are urgently needed.

Initial waterline contamination by Pseudomonas aeruginosa in newly installed dental chairs.

Water contamination in dental unit waterlines (DUWLs) is a potential source of healthcare-associated infection during dental care. The aim of this study was to evaluate the microbiological quality of DUWLs water from newly installed dental chairs in a French University Hospital. The microbiological quality of water from 24 new DUWLs initially disinfected by ICX Renew-prior to use of the dental units for patient treatment-was assessed for total culturable aerobic bacteria at 22°C and 36°C, Legionella sp., Pseudomonas aeruginosa, and total coliforms. Among the 24 samples analyzed, 21 were compliant with the water quality levels: 19 had no bacteria, and 2 contained only 4 and 1 CFU/mL for total culturable aerobic bacteria at 22°C and 36°C, respectively. Three samples were non-compliant due to contamination by P. aeruginosa (4, 2, and 2 CFU/100 mL). Controlling and preventing the microbiological contamination of DUWLs, especially by pathogenic bacteria, at the time of the installation of the new dental chairs are crucial to prevent healthcare-associated infection in dentistry. IMPORTANCE: Dental unit waterlines (DUWLs) of new dental chairs may be contaminated before their first clinical use, so an initial shock disinfection is crucial at the time of their installation. The microbiological analyses are crucial to control the water quality of DUWLs before their first clinical use because their disinfection does not guarantee the elimination of all bacteria.

A first step towards the detection of damage processes in endodontic Ni-Ti alloy files, using acoustic emission.

Despite major instrumental developments over the last decade, endodontic files are still not infallible. It is well known that NiTi rotary files can break without any visible sign of deformation. Instrument breakage under combined flexion-torsion loading is still common in clinical practice. Unfortunately, breakage of this type of instrument mainly occurs in narrow canals, through pinching in the apical region. When such an incident occurs, the endodontist must adopt a debris retrieval strategy that is both stressful and not guaranteed success. This study proposes a new method for experimental damage detection leading to the fracture of Ni-Ti shape memory alloy endodontic files. It is based on the acoustic emission (AE) technique and mechanical parameters measured in real-time and image analysis. It has been shown that the AE results correlate with the damage observations and torque and force measurements recorded during the tests. Having carried out numerous root canal treatment on resin blocks, it appears that this new detection and analysis technique can be used to analyze and anticipate the first signs of damage leading to endodontic file failure. The technological development of such a method, at the level of the engine itself, associated with the act in service procedure, would constitute a revolution in the field of endodontics.

Influence of endodontic motors on the behaviour of root canal shaping instruments: an in vitro comparative study.

AIMS: The endodontic literature reports a lot of comparative study on endodontic instruments, concerning as well their geometry, instrumental dynamics, material, mechanical behavior or heat treatment. However, to our knowledge, no study has focused on the influence of endodontic motors on the shaping abilities of endodontic instruments. Thus, the aim of this study was to analyze the influence of the endodontic motors on root canal shaping instruments. METHOD: Dual Move (MICRO-MEGA, Besançon, France), Canal Pro CL2i (COLTENE, Alstätten, Suisse), Canal Pro Jeni Motor (COLTENE, Alstätten, Suisse), Ai Motor (WOODPECKER, Guilin, China), Wave One motor (VDW, Postfach, Munich) and Smart A (WOODPECKER, Guilin, China) were pre-clinically compared in continuous rotation and reciprocating motion on a traction/compression bench using resin blocks. Canal shaping in continuous rotation and reciprocating motion were performed with One Curve and One RECI instruments (MICRO-MEGA, Besançon, France), respectively. The penetration/removal forces, making it possible to objectify the cutting effect and screwing effect of the instruments during root canal shaping, were analyzed. RESULTS: The results showed (i) that endodontic motors influence the mechanical behavior of endodontic instruments, (ii) that the influence of the motors is essentially felt during reciprocating motion and (iii) that the reciprocating angles influence the mechanical behavior of endodontic instruments. CONCLUSION: Only endodontic instruments are widely studied in literature while endodontic motors have a direct influence on root canal treatment. This study analyzes the influence of the endodontic motors on root canal shaping instruments. This study tends to demonstrate that Jeni Motor could optimize the mechanical behavior of endodontic instruments.

Ethical reflections on Covid-19 vaccines.

OBJECTIVES: More than 1 year after the start of the Covid-19 pandemic it is becoming increasingly clear that vaccines will prove to be essential in combating this global pandemic. The demand for such vaccines is great (since nearly everyone is a candidate for vaccination) yet supplies are currently limited. This raises clear ethical questions regarding the current and future Covid-19 vaccines. METHODS: In this paper we highlight the several ethical questions that are raised using a three-fold categorization. We will discuss questions concerning: (1) the design and testing of vaccines; (2) who gets the vaccines; and (3) the tensions between public health and individual interest/autonomy. Each of these three more broad categories encompasses many different and concrete ethical questions. RESULTS: We argue that different ethical frameworks apply both across these three categories, but also within these categories. CONCLUSION: Despite the fact that ethical conflict might not completely disappear, we argue that distinguishing and discussing separate questions from an ethical perspective can help create the necessary clarity and provide an ethical justification in favour of particular vaccination issues.

Virtual aids and students' performance with haptic simulation in implantology.

OBJETIVES: This study aims to validate that haptic simulator assistance could improve drilling ability in implantology and that the repetition of training session could highlight a learning curve. METHODS: This work was carried out with 88 first-year dental students. After randomization, students were divided into two groups. Group 1 was assigned to prepare an implant site for a left first mandibular molar (36) on haptic simulator with assistance provided by simulator. Group 2 had to perform the same exercise without assistance. Whatever the group, the maximum time for each reparation was restricted to 5 min. An interval of 1 week was done between each session. For each test, different objective parameters provided by the simulator were recorded and analyzed. RESULTS: This study showed that the presence of virtual aids led to quickly obtain better results, and the training led to gradually acquire sufficient competence to do without virtual aids. CONCLUSION: By associating virtual assistance and repetition, the student will acquire more quickly the skills allowing to carry out his clinical gestures in real conditions.

Analysis of ergonomic occupational accidents and near misses in a large Belgian university hospital.

INTRODUCTION: Health-care organizations are facing a high burden of ergonomic occupational accidents, and prevention is a continuous point of interest. In this manuscript, we describe the characteristics of ergonomic accidents in a large Belgian university hospital and discuss the value of near misses. METHODS: Combining databases, we identified the frequency [number of accidents × 106 hours worked per year], severity (number of days off work × 103 hours worked per year), and profile of the victims of occupational ergonomic accidents (with absence from work) or incidents or near-misses (without absence from work). Ergonomic accidents and incidents include slips, trips, falls, injurious body movements, overexertion, and handling heavy weights. RESULTS: In a period of 23 years, we noticed a significant decrease in the frequency of ergonomic accidents (from about 7 to about 4 standard units), without changes in the severity. The decrease in the frequency of accidents is mirrored by an increase in the frequency of incidents (from about 4 to about 6 standard units). Female and older employees are more vulnerable to accidents, and the frequency was between two and four times higher for employees mostly involved in manual tasks compared to employees mostly involved in managerial tasks. The profile of the victims and the causes of accidents and incidents were identical. CONCLUSION: Although it is premature to assume a cause-consequence relationship between incidents and accidents, it is tempting to speculate that the increased ratio of the frequencies of incidents over accidents might be one of the variables reflecting the adequacy of preventive measures and the growth of safety behavior.

Mathematical method to build an empirical model for inhaled anesthetic agent wash-in.

BACKGROUND: The wide range of fresh gas flow - vaporizer setting (FGF - FD) combinations used by different anesthesiologists during the wash-in period of inhaled anesthetics indicates that the selection of FGF and FD is based on habit and personal experience. An empirical model could rationalize FGF - FD selection during wash-in. METHODS: During model derivation, 50 ASA PS I-II patients received desflurane in O2 with an ADU® anesthesia machine with a random combination of a fixed FGF - FD setting. The resulting course of the end-expired desflurane concentration (FA) was modeled with Excel Solver, with patient age, height, and weight as covariates; NONMEM was used to check for parsimony. The resulting equation was solved for FD, and prospectively tested by having the formula calculate FD to be used by the anesthesiologist after randomly selecting a FGF, a target FA (FAt), and a specified time interval (1 - 5 min) after turning on the vaporizer after which FAt had to be reached. The following targets were tested: desflurane FAt 3.5% after 3.5 min (n = 40), 5% after 5 min (n = 37), and 6% after 4.5 min (n = 37). RESULTS: Solving the equation derived during model development for FD yields FD=-(e(-FGF*-0.23+FGF*0.24)*(e(FGF*-0.23)*FAt*Ht*0.1-e(FGF*-0.23)*FGF*2.55+40.46-e(FGF*-0.23)*40.46+e(FGF*-0.23+Time/-4.08)*40.46-e(Time/-4.08)*40.46))/((-1+e(FGF*0.24))*(-1+e(Time/-4.08))*39.29). Only height (Ht) could be withheld as a significant covariate. Median performance error and median absolute performance error were -2.9 and 7.0% in the 3.5% after 3.5 min group, -3.4 and 11.4% in the 5% after 5 min group, and -16.2 and 16.2% in the 6% after 4.5 min groups, respectively. CONCLUSIONS: An empirical model can be used to predict the FGF - FD combinations that attain a target end-expired anesthetic agent concentration with clinically acceptable accuracy within the first 5 min of the start of administration. The sequences are easily calculated in an Excel file and simple to use (one fixed FGF - FD setting), and will minimize agent consumption and reduce pollution by allowing to determine the lowest possible FGF that can be used. Different anesthesia machines will likely have different equations for different agents.

The performance of compartmental and physiologically based recirculatory pharmacokinetic models for propofol: a comparison using bolus, continuous, and target-controlled infusion data.

BACKGROUND: With the growing use of pharmacokinetic (PK)-driven drug delivery and/or drug advisory displays, identifying the PK model that best characterizes propofol plasma concentration (Cp) across a variety of dosing conditions would be useful. We tested the accuracy of 3 compartmental models and 1 physiologically based recirculatory PK model for propofol to predict the time course of propofol Cp using concentration-time data originated from studies that used different infusion schemes. METHODS: Three compartmental PK models for propofol, called the "Marsh," the "Schnider," and the "Schüttler" models, and 1 physiologically based recirculatory model called the "Upton" model, were used to simulate the time course of propofol Cp. To test the accuracy of the models, we used published measured plasma concentration data that originated from studies of manual (bolus and short infusion) and computer-controlled (target-controlled infusion [TCI] and long infusion) propofol dosing schemes. Measured/predicted (M/P) propofol Cp plots were constructed for each dataset. Bias and inaccuracy of each model were assessed by median prediction error (MDPE) and median absolute prediction error (MDAPE), respectively. RESULTS: The M/P propofol Cp in the 4 PK models revealed bias in all 3 compartmental models during the bolus and short infusion regimens. In the long infusion, a worse M/P propofol Cp at higher concentration was seen for the Marsh and the Schüttler models than for the 2 other models. Less biased M/P propofol Cp was found for all models during TCI. In the bolus group, after 1 min, a clear overprediction was seen for all 3 compartmental models for the entire 5 min; however, this initial error resolved after 4 min in the Schnider model. The Upton model did not predict propofol Cp accurately (major overprediction) during the first minute. During the bolus and short infusion, the Marsh model demonstrated worse MDPE and MDAPE compared with the 3 other models. During short infusion, MDAPE for the Schnider and Schüttler models was better than the Upton and the Marsh models. All models showed similar MDPE and MDAPE during TCI simulations. During long infusion, the Marsh and the Schüttler models underestimated the higher plasma concentrations. CONCLUSION: When combining the performance during various infusion regimens, it seems that the Schnider model, although still not perfect, is the recommended model to be used for TCI and advisory displays.

Past, present and future of university hospitals.

Objectives: Health care systems worldwide are changing and taking new forms. The old, more hierarchically oriented, model with individual institutional and bilateral interactions between primary, secondary, tertiary and quaternary care is being replaced by an integrated and dynamic network model. We aim to look at what role university hospitals will play in this future organization of health care.Method: In this paper, we look at the relevant literature on the history of academic medicine and university hospitals. Subsequently, we look at the challenges university hospitals are facing according to contemporary literature on the topic.Results: Our current model of academic medicine with its university hospitals finds its origin in the institutionalization of the academic mission in the late 18th century. Currently, the sustainability of the model is under immense pressure. University hospitals are facing economic challenges, teaching challenges and research challenges. However, there is reason to believe that they can continue to play a role of importance in tomorrow's medicine. The organization of health care is undergoing two important changes. The first is the evolution towards a more dynamic and integrated network model. University hospitals can become an important hub within this network. The second change is an evolution towards evidence based medicine and translational research.Conclusion: Due to their unique tripartite mission, we argue that university hospitals can continue to play an important and critical role in promoting evidence-based medicine and speedy translation of new evidence.

Contribution of Haptic Simulation to Analogic Training Environment in Restorative Dentistry.

The aim of this study was to evaluate the contribution of virtual reality to the conventional analogic training environment and show the complementarity of conventional techniques and virtual reality in the learning of dental students. All 88 first-year dental students at a dental school in France in early 2019 were randomly assigned to one of two groups: group 1 (n = 45) was assigned to cavity preparations on a haptic simulator (Virteasy) and group 2 (n = 43) was assigned to conventional practical work on plastic analogue teeth (Kavo). Following three training sessions, the students in group 1 took a final exam on the same plastic analogue teeth exercise. The results showed improvement in the drilling skill of both groups. The simulator-trained group (group 1) had similar results to the plastic analogue-trained group (group 2) in the final test on a plastic analogue tooth. In this study, virtual reality allowed an assessment based on objective criteria and reduced the subjectivity of evaluations conducted on plastic analogue teeth. Considering the saving of supervision and teaching time as well as the material gain offered by virtual reality, the learning methods of haptic simulators are educational options that should be considered by dental educators.

Response surface modeling of the interaction between propofol and sevoflurane.

BACKGROUND: Propofol and sevoflurane display additivity for gamma-aminobutyric acid receptor activation, loss of consciousness, and tolerance of skin incision. Information about their interaction regarding electroencephalographic suppression is unavailable. This study examined this interaction as well as the interaction on the probability of tolerance of shake and shout and three noxious stimulations by using a response surface methodology. METHODS: Sixty patients preoperatively received different combined concentrations of propofol (0-12 microg/ml) and sevoflurane (0-3.5 vol.%) according to a crisscross design (274 concentration pairs, 3 to 6 per patient). After having reached pseudo-steady state, the authors recorded bispectral index, state and response entropy and the response to shake and shout, tetanic stimulation, laryngeal mask airway insertion, and laryngoscopy. For the analysis of the probability of tolerance by logistic regression, a Greco interaction model was used. For the separate analysis of bispectral index, state and response entropy suppression, a fractional Emax Greco model was used. All calculations were performed with NONMEM V (GloboMax LLC, Hanover, MD). RESULTS: Additivity was found for all endpoints, the Ce(50, PROP)/Ce(50, SEVO) for bispectral index suppression was 3.68 microg. ml(-1)/ 1.53 vol.%, for tolerance of shake and shout 2.34 microg . ml(-1)/ 1.03 vol.%, tetanic stimulation 5.34 microg . ml(-1)/ 2.11 vol.%, laryngeal mask airway insertion 5.92 microg. ml(-1) / 2.55 vol.%, and laryngoscopy 6.55 microg. ml(-1)/2.83 vol.%. CONCLUSION: For both electroencephalographic suppression and tolerance to stimulation, the interaction of propofol and sevoflurane was identified as additive. The response surface data can be used for more rational dose finding in case of sequential and coadministration of propofol and sevoflurane.