Individual-finger motor imagery classification: a data-driven approach with Shapley-informed augmentation.

Objective. Classifying motor imagery (MI) tasks that involve fine motor control of the individual five fingers presents unique challenges when utilizing electroencephalography (EEG) data. In this paper, we systematically assess the classification of MI functions for the individual five fingers using single-trial time-domain EEG signals. This assessment encompasses both within-subject and cross-subject scenarios, supported by data-driven analysis that provides statistical validation of the neural correlate that could potentially discriminate between the five fingers.Approach. We present Shapley-informed augmentation, an informed approach to enhance within-subject classification accuracy. This method is rooted in insights gained from our data-driven analysis, which revealed inconsistent temporal features encoding the five fingers MI across sessions of the same subject. To evaluate its impact, we compare within-subject classification performance both before and after implementing this augmentation technique.Main results. Both the data-driven approach and the model explainability analysis revealed that the parietal cortex contains neural information that helps discriminate the individual five fingers' MI apart. Shapley-informed augmentation successfully improved classification accuracy in sessions severely affected by inconsistent temporal features. The accuracy for sessions impacted by inconsistency in their temporal features increased by an average of26.3%±6.70, thereby enabling a broader range of subjects to benefit from brain-computer interaction (BCI) applications involving five-fingers MI classification. Conversely, non-impacted sessions experienced only a negligible average accuracy decrease of2.01±5.44%. The average classification accuracy achieved is around 60.0% (within-session), 50.0% (within-subject) and 40.0% (leave-one-subject-out).Significance. This research offers data-driven evidence of neural correlates that could discriminate between the individual five fingers MI and introduces a novel Shapley-informed augmentation method to address temporal variability of features, ultimately contributing to the development of personalized systems.

Customized SmartPeg for measurement of resonance frequency of mini dental implants.

BACKGROUND: One-piece narrow diameter implants (NDIs) have been recommended as "Single-tooth replacements in the anterior zones, single posterior, multiple-unit fixed dental prosthesis (FDP), edentulous jaws to be rehabilitated with FDP, and edentulous jaws rehabilitation with overdentures in situations with reduced mesiodistal space or reduced ridge width." (ITI consensus 2013). Since NDIs can be immediately loaded, it is important to be able to carry out stability testing. We developed and validated a customized SmartPeg for this type of implant to measure the Implant Stability Quotient (ISQ). The ISQ of mini dental implants (MDIs) was measured and compared with the stability of standard and in a rabbit model. OBJECTIVE: The aim of the study is to test the feasibility of a customized SmartPeg for resonance frequency measurement of single-piece mini dental implants and to compare primary stability of a standard and the mini dental implant (3M™ESPE™ MDI) in a rabbit model after 6 weeks of healing. METHODS: Eight New Zealand white rabbits were used for the study. The protocol was approved by the McGill University Animal Ethics Review Board. Sixteen 3M™ESPE™ MDI and equal number of standard implants (Ankylos® Friadent, Dentsply) were inserted into the tibia/femur of the rabbits and compared. Each rabbit randomly received two 3M™ESPE™ MDI and two Ankylos® implants in each leg. ISQ values were measured with the help of an Osstell ISQ device using custom-made SmartPegs for the MDIs and implant-specific SmartPegs™ (Osstell) for the Ankylos®. Measurements were obtained both immediately following implant placement surgery and after a 6-week healing period. Each reading was taken thrice and their average compared using Wilcoxon matched pairs signed-rank tests. RESULTS: The median ISQ and interquartile range (IQR) values were 53.3 (8.3) at insertion and 60.5 (5.5) at 6 weeks for the 3M™ESPE™MDI and, respectively, 58.5 (4.75) and 65.5 (9.3) for the Ankylos® implant. These values also indicate that both types of implants achieved primary and secondary stability, and this is supported by histological data. ISQ values of both 3M™ESPE™ MDI and Ankylos® increased significantly from the time of insertion to 6 weeks post-insertion (p < 0.05). CONCLUSIONS: The new custom-made SmartPeg is suitable for measuring the Implant Stability Quotient of 3M™ESPE™MDIs. The primary stability of 3M™ESPE™MDIs is similar to the primary stability attained by standard implants in the rabbit tibia.

The mandibular retromolar area as a donor site in maxillofacial bone grafting: surgical notes.

Bone harvesting from the mandibular retromolar area represents an attractive approach to obtaining corticocancellous bone blocks for reconstruction of a deficient alveolar ridge. Knowledge of the local anatomy, adherence to proper surgical techniques, and judicious use of appropriate surgical armamentarium are paramount to minimizing operative hazards. The objective of this article is to review pertinent surgical notes related to the safe harvesting of corticocancellous bone blocks from the retromolar area using a trephine bur technique.

Management of a failed mandibular staple implant: a clinical report.

A 48-year-old woman sought treatment because her staple implant-retained overdenture was no longer retentive, and the denture was worn over the abutments. After unsuccessfully attempting to move the retentive nuts along the transosseous posts of the staple implant, the posts were cut off at the level of the bone. Two endosseous implants were placed around the staple implant, and a new implant-retained overdenture was fabricated and inserted using ball attachments for retention. This article describes the treatment for this patient, who has been wearing the new dentures successfully for the past 4 years.

Methodology for measuring the in vitro seating and unseating forces of prefabricated attachment systems used to retain implant overdentures.

PURPOSE: The purpose of this in vitro investigation was to measure the forces generated during the continuous seating and unseating of prefabricated attachment systems used to retain implant overdentures. MATERIALS AND METHODS: An experimental design consisting of interchangeable fixture mounts, a radially indexable fixture holder, and a materials testing systems (MTS) machine was used to measure forces generated during the insertion and removal of spherical stud attachments (Straumann, Inc, Waltham, WA). Three separate experiments were conducted measuring the seating and unseating forces of a vertically aligned patrix/matrix assembly, a 20 degrees angled patrix opposing a vertically positioned matrix, and a vertically positioned patrix opposing a 20 degrees angled matrix. For each patrix/matrix combination, three specimens were tested. Measurements were continuously recorded under reproducible conditions in the presence of artificial saliva. All specimens were subjected to 10,000 seating/unseating cycles. Statistical analysis was performed with rank analysis of variance (ANOVA) for a group comparison (alpha= 0.05). RESULTS: Results showed variability in the initial insertion and removal forces among experimental groups and among specimens within each experiment. A marked increase in the seating and unseating forces was recorded for all specimens during the first 300 cycles, followed by a gradual decrease in these forces. The exact p-values for the Kruskal-Wallis test showed no significant difference between the initial and final seating/unseating forces (p > 0.1) nor in the maximum seating/unseating forces (p > 0.6) among the three experimental groups. CONCLUSIONS: Spherical stud attachments exhibited consistent seating and unseating forces over 10,000 cycles. A 20 degrees angle between the patrix and matrix had no effect on the overall seating and unseating force values.

Video-assisted clinical instruction in dentistry. Overview and applications.

Dental education can benefit from adopting new technologies and modern learning practices. Video-assisted clinical instruction in dentistry (VACID) uses video technology with the purpose of enhancing the teaching of technical skills and the acquisition of clinical knowledge, as well as fostering student-centered learning and critical self-appraisal. VACID is made possible through the capturing, recording, transmitting and viewing of high quality video images of live or pre-recorded clinical procedures. As such, the implementation of VACID represents an attractive teaching tool that can complement and strengthen current clinical and didactic teaching practices used in formal dental education. The primary objective of this paper is to provide an overview of VACID and discuses its various applications in dental education. A second objective of this paper is to provide a detailed description of the video camera set-up used at the University of Iowa for the implementation of VACID in the Department of Periodontics.

Video-Assisted Clinical Instruction in Dentistry (VACID) enhances real-time visualisation of clinical procedures.

AIM: The use of Video-Assisted Clinical Instruction in Dentistry (VACID) in the training of dental students represents an innovative teaching medium. Despite the many advantages that this teaching medium promises to offer, little objective research has been published to substantiate its purported benefits. This article examines the students' response to the application of VACID to enhance real-time visualisation of clinical procedures while observing live clinical procedures in periodontics. METHOD: Forty third-year dental students, observing surgical procedures during their rotation in the Department of Periodontics, were invited to participate in a survey designed to examine perceptions relating to their learning experience to using conventional and video-assisted real-time visualisation of clinical procedures. Students' responses were obtained using a questionnaire administered immediately after the completion of the observational period. The survey employed attitude questions addressing both enabling and outcome criteria. Wilcoxon signed-rank test was used to compare the student's responses. An open-ended question was also included in the survey to give students the opportunity to provide additional feedback regarding their experience and suggestions to improve on it. RESULTS: Results suggest that the implementation of VACID in the clinical setting improves the student's learning experience, interest and satisfaction. Ninety per cent of students strongly agreed to have VACID implemented for their next clinical observation. Responses to the open-ended question indicated that improved visualisation was extremely helpful in understanding the progress of clinical procedures. CONCLUSION: The implementation of VACID in the clinical setting enhances real-time visualisation of surgical procedures beyond what is offered by the conventional observational format.

Enhancing restorative, periodontal, and esthetic outcomes through orthodontic extrusion.

Traumatic tooth fractures, dental caries, and overzealous tooth preparations can lead to the loss of coronal tooth structure, thus complicating the definitive prosthetic plan. Although exposure of additional clinical tooth structure by surgical crown lengthening is often recommended, such an approach is usually discouraged because of the possible adverse periodontal changes to the adjacent teeth and compromised esthetics, especially in the presence of an otherwise intact arch. This article discusses the application of orthodontic extrusion to conservatively restore a single tooth with minimal coronal tooth structure in the esthetic zone. A detailed description of the prosthetic approach used before, during, and after orthodontic therapy is presented.

Fabrication of a surgical template for implant/bar-retained mandibular overdentures.

To achieve long-term success with an implant-retained overdenture, application of force in the path of insertion of the prosthesis has been recommended. This implies that the retentive matrices and the implants are positioned parallel to each other and to the path of insertion of the prosthesis. This article describes a technique for the fabrication of a surgical template for an implant-retained overdenture in the mandible. Adherence to the guidelines proposed in this article will lead to optimal implant placement in a consistent and repeatable manner.

Effects of FGF-2/-9 in calvarial bone cell cultures: differentiation stage-dependent mitogenic effect, inverse regulation of BMP-2 and noggin, and enhancement of osteogenic potential.

Systemically administered fibroblast growth factors (FGFs) show anabolic effects on bone formation in animals, whereas in vitro cell culture studies have demonstrated that FGFs block mineralized bone nodule formation. These apparently contradictory outcomes indicate that the nature of FGF action is complex and that the biological effect of FGFs may depend on the differentiation stage of osteoblasts, interaction with other cytokines, or the length and mode of exposure to factors. Thus, we have utilized primary calvarial bone cell populations at different maturation phases to determine their responses to 2, FGF-9, and BMP-2, the factors expressed in bone. FGF-2 and FGF-9 stimulated proliferation of the cell populations consisting of more mature osteoblasts, but not those with undifferentiated precursor cells. Continuous treatment with FGF-2/-9 inhibited expression of several osteoblast marker genes and mineralization. However, brief pretreatment with FGF-2/-9 or sequential treatment with FGF-2/-9 followed by BMP-2 led to marked stimulation of mineralization, suggesting that FGFs enhance the intrinsic osteogenic potential. Furthermore, FGF-2 and FGF-9 increased expression of other osteogenic factors BMP-2 and TGFbeta-1. Meanwhile, blocking endogenous FGF signaling, using a virally transduced dominant-negative FGF receptor (FgfR), resulted in drastically reduced expression of the BMP-2 gene, demonstrating for the first time that endogenous FGF/FgfR signaling is a positive upstream regulator of the BMP-2 gene in calvarial osteoblasts. In contrast, expression of a BMP antagonist noggin was inhibited by FGF-2 and FGF-9. Thus, collective data from this study suggest that FGF/FgfR signaling enhances the intrinsic osteogenic potential by selectively expanding committed osteogenic cell populations as well as inversely regulating BMP-2 and noggin gene expression.

Chitosan supports the initial attachment and spreading of osteoblasts preferentially over fibroblasts.

The aim of this study was to determine chitosan's effect on osteoblast and fibroblast cell attachment. Mouse MC3T3-E1 osteoblasts and 3T3 fibroblasts were grown in the presence of serum on two commercially available chitosans, Chitosan-H (CH) and Protasan CL212 (PR). Cell attachment and immunofluorescent analysis at various time points were done to analyze initial phenotypic profiles. At 1h, significantly (P<0.05) fewer fibroblasts attached to CH or PR than serum-coated substrates. Osteoblast attachment to the same biopolymers at 1h was significantly greater than those seen with fibroblasts. At 24 h, levels of cell attachment for fibroblasts to both CH and PR significantly increased and were similar to levels seen in osteoblast cultures at both 1 and 24 h. Morphologically, immunofluorescent analysis showed that osteoblasts plated on the biopolymers were attached and beginning to spread at 1h, whereas fibroblasts appeared more rounded. At 24 h, fibroblasts plated on CH or PR revealed a heterogeneous population of round and semi-spread cells. In comparison, osteoblasts displayed phenotypes that were well spread with a developed cytoskeleton. These results suggest that CH and PR support the initial attachment and spreading of osteoblasts preferentially over fibroblasts, and that manipulation of the biopolymer can alter the level of attachment and spreading.