Search Results (9)

Background: A critical review of the literature demonstrates that masticatory apparatus with an artificial oral environment is of interest in the fields including (i) dental science; (ii) food science; (iii) the pharmaceutical industries for drug release. However, apparatus that closely mimics human chewing and oral conditions has yet to be realised. This study investigates the vital role of dental morphology and form–function connections using two-bite test parameters for effective drug release from medicated chewing gum (MCG) and compares them to human chewing efficiency with the aid of a humanoid chewing robot and a bionics product lifecycle management (PLM) framework with built-in reverse biomimetics—both developed by the first author. Methods: A novel, bio-engineered two-bite testbed is created for two testing machines with compression and torsion capabilities to conduct two-bite tests for evaluating the mechanical properties of MCGs. Results: Experimental studies are conducted to investigate the relationship between biting force and crushing/shearing and understand chewing efficiency and effective mastication. This is with respect to mechanochemistry and power stroke for disrupting mechanical bonds releasing the active pharmaceutical ingredients (APIs) of MCGs. The manuscript discusses the effect and the critical role that jaw physiology, dental morphology, the Bennett angle of mandible (BA) and the Frankfort-mandibular plane angle (FMA) on two-bite test parameters when FMA = 0, 25 or 29.1 and BA = 0 or 8. Conclusions: The impact on other scientific fields is also explored. Full article

Objective: To evaluate mandibular kinematics in an orthodontic population using the Modjaw^® optical jaw tracking system. Materials and methods: A total of 154 orthodontic patients underwent mandibular kinematic analysis using the Modjaw^® system. ANB values determined skeletal classification, while dental classification was assessed on digital casts. The Modjaw^® records were taken as instructed by the manufacturer, and data collected from the readings included the discrepancy between centric occlusion and maximum intercuspation, maximum opening, Bennett angles, and sagittal condylar guidance. The presence or absence of temporomandibular disorders was determined by the DC-TMD questionnaires. Non-parametric tests and Spearman correlations were applied for the statistical analysis. Results: Significant differences in mandibular kinematics were observed between skeletal classes, particularly in CO-MI discrepancies, Bennett angles, and maximum opening (p < 0.05). TMD symptoms were associated with higher absolute CO-MI discrepancies but did not significantly alter other kinematic parameters. Weak correlations were found between sagittal condylar guidance and anterior guidance variables. Conclusions: Mandibular kinematics differ by skeletal classification, with Class III patients demonstrating distinct patterns. While TMD symptoms impact CO-MI discrepancies, overall mandibular dynamics remain consistent. Full article

Background/Objectives: Eccentric bruxism is a complex parafunctional activity that involves grinding of teeth and occurs more frequently during sleep. This study aimed to assess differences in condylar parameters (sagittal condylar inclination -SCI and Bennett angle -BA) and mandibular and condylar kinematics during functional and parafunctional movements in bruxers and non-bruxers and to assess a digital method for quantifying eccentric bruxism using an optical jaw tracking system (Modjaw^®). Methods: The study group included subjects diagnosed with eccentric bruxism according to validated clinical diagnostic criteria. A control group of non-bruxer subjects with demographic characteristics similar to the study group was considered. Each participant underwent Modjaw^® examination twice to assess the recordings’ repeatability. The anterior guidance, mastication, and simulated eccentric bruxism were recorded. The SCI and BA were computed. The trajectories of interincisal inferior point (IIP), left condyle (LC), and right condyle (RC) in the frontal (F), sagittal (S), and horizontal (H) planes were outlined in rectangles to calculate areas of mastication and areas of eccentric bruxism (mm²). Intraclass correlation coefficient (ICC) was used to assess the recordings’ repeatability. Comparisons between groups were performed using Student’s t- and Mann–Whitney tests. The receiver–operator characteristic (ROC) curve was used to assess the diagnostic quality of the digital method. Results: Twenty bruxers (10 F and 10 M) and 20 non-bruxers (10 F and 10 M) were included. The ICC had values higher than 0.85. SCI, BA, and area of mastication for IIP, LC, and RC were similar between the groups (p > 0.05). The area of eccentric bruxism was significantly wider in the bruxers (p < 0.001). According to the ROC curve, the following cut-off areas (mm²) for eccentric bruxism were found in F, S, and H planes: IIP (18.05, 13.43, 16.28); LC (3.74, 10.83, 3.35); and RC (4.21, 10.63, 2.9), corresponding to sensitivity > 0.8, specificity > 0.75 and area under the curve (AUC) > 0.85. Conclusions: Mandibular and condylar kinematics during functional movements were similar in bruxers and non-bruxers. A novel digital method for quantifying eccentric bruxism was found using Modjaw^®, which could serve as a tool for early detection of eccentric bruxism before the onset of clinical consequences. Full article

Background: The main aim of this research was to assess the reliability of two systems designed specifically for condylar movement recording using condylar slope and Bennett angle information. The objectives were to evaluate the validity of two subsequent null hypotheses: (1) there is no significant difference between the measurements of condylar slope and Bennett angle taken at T0 (initial) and T1 (after one week) using the same equipment; (2) there is no notable difference in the values of the condylar slope and Bennett angle measurements obtained using Modjaw and Cadiax 2. Methods: An observational, descriptive, and prospective study was conducted with a selected group of 25 individuals (13 females and 12 males) aged between 22 and 27. Results: The results of Cadiax 2 and Modjaw showed excellent measurement repeatability for both parameters, with intraclass correlation coefficients (ICC) above 0.90, indicating excellent reliability between T0 and T1, both at 3 mm and 5 mm of displacement. Modjaw had an overall average value relatively higher than Cadiax 2, even though Modjaw’s condylar slope at 5mm had a significantly lower average value (37.4 ± 6.31) with an interval of 24.5–48.1, which was lower than Cadiax 2 (48.4 ± 10.6) with an interval of 30.5–68.5. Regarding the primary aim, it can be stated that both Modjaw and Cadiax 2 demonstrated excellent repeatability on their own, demonstrating robust reliability since there was no discernible difference between the T0 and T1 measurements. On the contrary, analyses of the two devices’ measured values for the secondary aim showed a considerable difference. Conclusions: Even though each device is reliable on its own, the absolute values that are obtained are different. Technological differences between the systems may account for these variations. Full article

Sports activities may induce long-lasting changes in mandibular trajectories. The aim was to compare condylar and mandibular movements in athletes with orofacial injuries with values measured in non-injured athletes. The group of 132 athletes without mandibular injury included asymptomatic athletes with a history of a blow to the right side (N = 43) and the group included asymptomatic athletes with a history of a blow to the left side (N = 41) of the mandible. The injured athletes suffered from stiffness/pain and/or limitation of jaw movements. The symptoms disappeared shortly after the injury. Athletes with a history of injury have smaller mean values of Bennett angle on the side of impact, and Bennett angle on the opposite side is greater than the mean found in non-injured athletes. Significantly smaller Bennett angle values in athletes with a history of a blow to one side of the mandible are due to the adaptability of the orofacial system. The larger Bennett angle on the opposite side of the injury is also due to the adaptive mechanism of the TMJ. Clinical Relevance: An individualized approach to TMJ values is mandatory in restorative procedures in every patient, especially in patients with a history of trauma to the orofacial system. Full article

Background: With the introduction of high-tech appliances, anchorage devices, and improved patient awareness of the risks associated with maxillofacial surgery, treating complex situations with orthodontic treatment has become more difficult in recent years. This study was conducted to demonstrate that orienting the occlusal plane, all the dental, skeletal, and soft tissue parameters, would be improved and to find which of these parameters could be correlated with the steepness of the occlusal plane. Materials and methods: This was a retrospective study including 40 cephalometric interpretations for patients who were planned for four-unit extractions (20 cephalometric radiographies before treatment and 20 after finishing the treatment). All were treated in the same orthodontic clinic with the same protocol using the McLaughlin–Bennett–Trevisi (MBT) prescription, with 22 slots and one-step retraction following four-unit extraction based on temporary anchorage devices (TADs). Results: There was no significant change in the canting of the occlusal plane, and it remained relatively stable from 6.31° to 7.55°, while all the soft tissue-related cephalometric measurements were reduced significantly, except the nasolabial angle, as the relation of the upper and lower lip to the esthetic line of Ricketts’ (E-Line) was reduced by 2.91 and 2.46°, respectively; furthermore, the angle of convexity was reduced from 10.92° to 9.79°. Besides, the upper incisor display was reduced by 0.38° Conclusions: Both the Frankfort mandibular angle and upper-incisor-to-Frankfort horizontal plane were significant parametric factors associated with profile change after extraction treatment having a positive 0.01-level Pearson association with occlusal plane steepness. Therefore, using the MBT prescription with TAD-based retraction is one of the favorable methods for the management of complex cases. Full article

(1) Background: The temporomandibular joint (TMJ) is the most complex and one of the most important joints in the human body due to its essential roles in mastication, swallowing, breathing and speech. Several instruments have been used to track mandibular movements and register the characteristic parameters of the TMJ, among which condylography instruments are validated for the accurate clinical registration of the condylar path. Sagittal condylar inclination (SCI) is one of the most important parameters, together with the Bennett angle and the immediate side shift, used for articular settings in the process of oral rehabilitation. The aim of the present study was to evaluate the differences between the left and right SCI and to assess whether the differences were statistically significant for skeletal class, age, gender, dentate status, TMJ pathology or parafunctional habits. (2) Methods: One hundred and forty consecutive patients, fully dentate or partially edentulous, and with angle class I, II and II, were recruited. Their left and right SCIs were determined with an ultrasonic jaw tracking device. Each subject had to make three protrusive movements and three right and left laterotrusive movements. The software calculated the SCI from the mean of the protrusive movements. (3) Results: The mean values obtained for the right and left SCI were 34.68° (±12.44°) and 34.94° (±13.23°), respectively, with no statistically significant differences between the left and right values for gender, dentate status, TMJ disorders or parafunctional habits. Skeletal class III subjects registered lower SCI means, which were statistically significant for the left SCI. (4) Conclusions: For an optimal functionalization of prosthetic restorations and for an ideal treatment plan, the registration of both the left and right paths of the condyles and the articular disc should be taken into consideration. Full article

The security analysis of the Ekert 1991 (E91), Bennett 1992 (B92), six-state protocol, Scarani–Acín–Ribordy–Gisin 2004 (SARG04) quantum key distribution (QKD) protocols, and their variants have been studied in the presence of collective-rotation noise channels. However, besides the Bennett–Brassard 1984 (BB84) being the first proposed, extensively studied, and essential protocol, its security proof under collective-rotation noise is still missing. Thus, we aim to close this gap in the literature. Consequently, we investigate how collective-rotation noise channels affect the security of the BB84 protocol. Mainly, we study scenarios where the eavesdropper, Eve, conducts an intercept-resend attack on the transmitted photons sent via a quantum communication channel shared by Alice and Bob. Notably, we distinguish the impact of collective-rotation noise and that of the eavesdropper. To achieve this, we provide rigorous, yet straightforward numerical calculations. First, we derive a model for the collective-rotation noise for the BB84 protocol and parametrize the mutual information shared between Alice and Eve. This is followed by deriving the quantum bit error rate (QBER) for two intercept-resend attack scenarios. In particular, we demonstrate that, for small rotation angles, one can extract a secure secret key under a collective-rotation noise channel when there is no eavesdropping. We observe that noise induced by rotation of 0.35 radians of the prepared quantum state results in a QBER of 11%, which corresponds to the lower bound on the tolerable error rate for the BB84 QKD protocol against general attacks. Moreover, a rotational angle of 0.53 radians yields a 25% QBER, which corresponds to the error rate bound due to the intercept-resend attack. Finally, we conclude that the BB84 protocol is robust against intercept-resend attacks on collective-rotation noise channels when the rotation angle is varied arbitrarily within particular bounds. Full article

This case report describes a 70 year-old man with IVA lung cancer who required oral function rehabilitation by fabricating dentures with a simplified clinical remount technique. A pair of dentures were fabricated for a 70-year-old man with stage IVA lung cancer. Due to severe bimaxillary exostoses, the dentures could not properly extend and achieve a peripheral seal. The treatment philosophy was to stabilize the dentures and achieve proper function with optimized occlusion. The simplified Lauritzen clinical remount technique was performed at the time of denture delivery and 3 months later. After the second clinical remount procedure, the patient was able to eat meals with the dentures and maintained in a stable condition. Compared with the original technique, the simplified Lauritzen clinical remount omits the facebow transfer and keeps the condylar guidance setting and the Bennett angle unchanged during the adjustment. The prostheses are mounted to a type 3, non-arcon type articulator with anterior stop screws attached to the bilateral condylar parts. With the aid of anterior stop screws, the eccentric movement of dentures can be differentiated on a millimeter scale and balanced easily. It is effective to use occlusal-optimized dentures and the clinical remount technique, especially in difficult cases. Full article