Guidance Angle Research Articles

The correlation analysis between incisal guidance angle and occlusal plane angles and temporomandibular joint morphology.

The correlations between the incisal guidance angle (IGA) and occlusal plane angles and temporomandibular joint (TMJ) morphology were investigated in adults with skeletal Class II division II malocclusion. CBCT images of 37 patients were analyzed. It included 19 cases of skeletal Class II division II malocclusion with low angle (study group) and 18 cases of skeletal Class I average angle (control group). The Invivo Dental 5 software was employed to acquire the data of the incisal guidance angle (IGA), occlusal plane angle (FH-OP), anterior occlusal plane angle (FH-AOP) and the TMJ measurement items. The results of IGA, FH-AOP angle and FH-OP angle showed the study group > the control group (P < 0.05). There were statistically difference in the condylar mediolateral diameters, articular eminence inclination and height, and posterior joint spaces between two groups. No differences were revealed in the condylar anteroposterior diameters, the condylar inclination angle, condylar head width and height, condylar length, glenoid fossa depth and width between two groups. In the study group, IGA showed a moderate correlation with FH-AOP, a weak correlation with FH-OP and condylar mediolateral diameters. Meanwhile, there was a correlation between FH-AOP, FH-OP, and TMJ indicators. The IGA was not only related to FH-AOP and FH-OP, but also to the condylar mediolateral diameters. In addition, there was a correlation between the occlusal plane angles and TMJ morphology in skeletal Class II division II low angle malocclusion. For patients with skeletal Class II division II low angle malocclusion, adjusting the IGA and the occlusal plane angles could improve the esthetic appearance of the anterior teeth, occlusal function, and TMJ morphology.

A comparative assessment of condylar inclination in completely edentulous patients using cone beam computed tomography and Arcus digma II

Statement of problemCondylar inclination affects denture fabrication and placement, especially when bilateral balanced occlusion is provided. However, comparisons between radiographic techniques and clinical procedures are lacking. PurposeThe purpose of this clinical study was to investigate the effects of cone beam computed tomography (CBCT) and Arcus digma II on horizontal condylar inclination and bilateral balanced occlusion. Material and methodsTwelve completely edentulous individuals were provided with complete dentures with teeth in bilateral balanced occlusion. The horizontal condylar angle was measured using CBCT and the Arcus digma II with a 6-mm mandibular protrusion. The CBCT had a real-time 3D image, and the Arcus digma II method recorded mandibular movement using electronic sensors. To evaluate the clinical performance, the horizontal condylar angle was measured using the 2 methods and applied to the semi-adjustable articulator to evaluate the balanced occlusion. The Shapiro-Wilk test was used to assess normality, and a paired t test was used to assess the normally distributed data (α=.05). ResultsThe horizontal condylar guidance angle values for both sides of Arcus digma II were significantly higher than from CBCT (P<.05). No difference was found in the clinical performance of balanced occlusion of complete dentures in the 2 methods. ConclusionsThe Arcus digma II method yielded higher horizontal condylar angle measurements than from CBCT. However, no significant difference was found between Arcus digma II and CBCT in terms of the effect on balanced occlusion. Arcus digma II appears to be a reliable technique for measuring the horizontal condylar angle, similar to CBCT, and can be used as an alternative method.

Comparison of Sagittal Condylar Guidance Angle Obtained by Radiographic Methods and Manual Programming of Articulators in Dentate Patients – A Clinico-radiographic Study

Background: The ultimate goal of advanced procedures in prosthetic dentistry is to construct a prosthesis based on the accurate reproduction of condylar guidance. Aim: To compare the sagittal condylar inclination obtained using the cone-beam computed tomography (CBCT), panoramic image, and two articulator systems. Settings and Design: A cross-sectional study was carried out in 20 dentate patients in the age group of 20–40 years. Materials and Methods: Sagittal condylar guidance angles (SCGAs) were measured on two semi-adjustable articulators (Hanau Wide Vue and Denar Mark 320) using protrusive interocclusal record. SCGAs were also measured on the CBCT scans (CBCT reconstructed panoramic image and CBCT sagittal cross section) and the panoramic images obtained from the patients. The angles were determined on the radiographs by joining two lines: Frankfort’s horizontal plane and the other plane were drawn by connecting the superior-most point on the glenoid fossa and the inferior-most point on the articular eminence. All the measurements were done twice by two operators independently. Statistical Analysis Used: The data were analyzed using the paired t-test and Pearson’s correlation coefficient with a P ≤ 0.05. Results: There was no significant difference between the right and the left side in any of the groups (P ≥ 0.05). In addition, there was no significant difference between the clinical methods (P ≥ 0.05). However, there was a significant difference between the clinical and the radiographic methods (P ≤ 0.05). Furthermore, there was a strong correlation between the clinical and radiographic methods with Pearson’s Correlation coefficient above 0.67. Conclusion: There is a strong correlation between the clinical and radiographic methods. Thus, CBCT and OPG can be used an adjunct to clinical methods to record sagittal condylar guidance.

Three‐dimensional path following control of underactuated autonomous underwater vehicles with nonzero roll dynamics: A novel line‐of‐sight‐guided approach

AbstractMost existing path following control approaches for underactuated Autonomous underwater vehicles (AUVs) assumed that the roll angle can be passively stabilized at zero, and simplified the problem to the 5‐degree‐of‐freedom model. However, in practice, the roll motion suffers from undesirable oscillations induced by environmental disturbances, unbalanced propeller torque, etc. To preserve the stability of the system under nonzero roll dynamics, this paper proposes a novel line‐of‐sight‐ (LOS) guided path following control approach. Firstly, the spatial path following error dynamics model is derived to comprehensively reveal the negative effect of roll dynamics. Secondly, an improved LOS guidance law is designed to compensate for the nonzero roll angle. A salient feature is that the proposed guidance law can be applied to the underwater vehicle no matter it is underactuated in the roll motion or not. Thirdly, by assigning the guidance angles to the desired attitude angles, a robust attitude tracking controller is developed, in which the adaptive estimation technique is employed to handle the lumped uncertainties. The tanh‐based saturation function is incorporated such that the resultant control signals are inherently bounded. The closed‐loop path following and attitude tracking errors are proved to be globally asymptotically stable at the origin. Comparative simulation results are provided to substantiate the effectiveness and superiority of the proposed method.

A Novel Unmanned Surface Vehicle Path-Planning Algorithm Based on A* and Artificial Potential Field in Ocean Currents

Ocean currents make it difficult for unmanned surface vehicles (USVs) to keep a safe distance from obstacles. Effective path planning should adequately consider the effect of ocean currents on USVs. This paper proposes an improved A* algorithm based on an artificial potential field (APF) for USV path planning in a current environment. There are three main improvements to the A* algorithm. Firstly, the proposed algorithm ignores unnecessary perilous nodes to decrease calculation. Secondly, an adaptive guidance angle is developed to guide the search in the most appropriate direction to reduce the computing time. Thirdly, the potential field force function is introduced into the cost function to ensure that the path designed for the USV always maintains a safe distance from obstacles under the influence of ocean currents. Furthermore, the Bezier curve is adapted to smooth the path. The experimental results show that the USV path-planning algorithm proposed in this paper, which synthesizes the APF and A* algorithms, runs 22.5% faster on average than the traditional A* algorithm. Additionally, the path developed by the proposed A* algorithm effectively keeps appropriate and different distances from obstacles by considering different ocean currents.

A systematic review and meta-analysis of accuracy between protrusive interocclusal record and horizontal condylar guidance angle recording methods in dentulous patients.

This systematic review and meta-analysis aimed to evaluate the accuracy of different methods used for measuring horizontal condylar guidance (HCG) angle in comparison with protrusive interocclusal record (IOR) for dentulous patients. The design involves systematic review and meta-analysis following the Preferred Reporting Items for Systematic Review and Meta-analysis guidelines. An electronic search was carried out by two reviewers in the Google Scholar search engine and the EBSCO host, Cochrane Library, and PubMed/MEDLINE databases for quasi-experimental studies, in vivo studies, and cross-sectional studies published from January 2005 to February 2023 determining the HCG angle in dentulous patients. Meta-analysis was performed to evaluate the quantitative data. A total of 577 articles were identified, 29 analytical cross-sectional studies that fulfilled the eligibility criteria were included for qualitative synthesis and 26 studies were included for meta-analysis. A statistically significant difference was observed for the right and left HCG angles obtained by the panoramic radiograph method and cone-beam computed tomography (CBCT) method and for the right side HCG angle obtained by cephalogram method showing higher values than the protrusive IOR method. No statistically significant difference was observed for the left side HCG angle obtained by the cephalogram method and both the right and left side HCG angles obtained by the intraoral tracer method. The panoramic radiograph, cephalogram, and CBCT obtained higher HCG angles in dentulous patients than the protrusive IOR method.

Clinical evaluation of three different anterior reference points on protrusive condylar guidance angle using a semi adjustable articulator and lateral cephalogram

Background: Studies had shown that different anterior reference points can mount the maxillary cast in variable position in the articulator which may affect the protrusive condylar guidance angle on setting the semi adjustable articulator. So there is a need for search of reliable anterior reference point in orienting the maxillary cast on the articulation for accurate prosthesis fabrication. Aim: The aim of this study was to determine the effect of 3 different anterior reference points Orbitale, Orbitale minus 7mm, 36mm from the incisal edge of maxillary central or lateral incisor on the protrusive condylar guidance values registered on Hanau wide vue articulator and compare it to the protrusive condylar guidance angle obtained from lateral Cephalometric tracings. Materials and methods: A total of 30 healthy human subjects were randomly selected for this study from volunteer dental students. Orbitale, Orbitale minus 7mm, 36mm from the maxillary incisal edge of the subjects were the three anterior reference points used for facebow transfer using Hanau springbow. With the help of protrusive records, articulation was done in Hanau wide vue articulator using this record and condylar inclination values were noted on right side and left side.Three sets of lateral cephalometric radiographs were taken in maximum intercuspation and protrusive position, traced manually and values tabulated for all 30 subjects. Results: Mean value of orbitale is highest and mean value of 36mm from the maxillary incisal edge is lowest. Conclusion: Orbitale can be used as a reliable anterior reference point in facebow transfer using hanau wide vue articulator.

Lumped hydrodynamics identification-based cascade control for vertical-plane tracking of a fin-driven autonomous underwater vehicle

This paper aims to achieve a simplified and effective vertical-plane tracking control for a kind of fin-driven under-actuated autonomous underwater vehicles (AUVs). To this end, a two-layer framework of offline identification and online control is constructed and implemented for depth-pitch coupled tracking control of an under-actuated AUV at a constant forward speed. A simplified three-order identification model for pitch dynamics is derived and then a dedicated recursive weighted least squares algorithm is used to complete the offline estimation of lumped hydrodynamics. Subsequently, relying on identification results, an online cascade controller with just two gains and without any adaptive estimation is proposed to track the pitch guidance angle and it is proven to be input-to-state stable. Finally, comparative simulation results illustrate the effectiveness and outperformance of this two-layer framework for vertical-plane tracking control of fin-driven under-actuated AUVs.

Comparative Evaluation of the Horizontal Condylar Guidance Using Protrusive Interocclusal Records, OPG, and CBCT in Edentulous Patients: An In Vivo Study.

A clinical study to compare the horizontal condylar guidance using protrusive interocclusal records, orthopantomography (OPG), and cone-beam computed tomography (CBCT) in edentulous patients. Thirty-six edentulous subjects were selected as per predetermined criteria. Horizontal condylar guidance was recorded using protrusive interocclusal records (PIR), OPG, and CBCT for each patient. The PIR were obtained using extraoral Gothic arch tracers to program the Hanau articulator. The horizontal condylar guidance angles (HCGAs) were digitally constructed using appropriate software along the posterior slope of articular eminence for all radiographs. The collected data were recorded, tabulated, and statistically analyzed. The condylar guidance angle values were tested for significance to compare the different angles. The correlation of HCGA measurements on both sides between the three groups was analyzed. The PIR and OPG methods (p = 0.001), as well as the OPG and CBCT methods (p = 0.001), show substantial differences on both sides. On the contrary, the PIR and CBCT methods did not differ significantly (p = 0.11). Cone-beam computed tomography is as reliable and accurate as the clinical method. A significant correlation exists between the clinical method and CBCT. It can be used as a dependable adjunct to the clinical method of HCGA measurement. Cone-beam computed tomography can overcome the shortcomings of the conventional clinical methods to determine the accurate horizontal condylar guidance angulation measurement. It is safer with minimum discomfort and wastage of time for the patients.

Comparative Evaluation of Condylar Guidance Angles Measured Using Arcon and Non-Arcon Articulators and Panoramic Radiographs-A Systematic Review and Meta-Analysis.

The condylar guidance value (CGV) measurement constitutes an important part of a holistic prosthodontic treatment plan, with horizontal CGVs (HCGVs) and lateral CGVs (LCGVs) being two of the most prominently recognized. This systematic review aimed at evaluating the efficacy of two different types of CGV measurement protocols-articulators (both arcon and non-arcon) and panoramic radiographs. Additionally, it attempts to determine which of the mentioned methods performs better across several parameters. Several important web databases were searched using search terms derived from medical subject headings (MeSH), using keywords linked to "Arcon articulator", "Condylar guidance angle", "non-arcon articulator", "Panoramic x-ray" and "Radiographic examination", which constituted the first step in the study selection strategy. After completion, the search strategy which initially turned up to 831 papers, eventually ended up with 13 studies. The review and subsequent meta-analysis revealed that panoramic radiographs had noticeably greater efficacy in terms of the CGVs as compared to the articulators in the majority of the studies. Within the articulators, the arcon types recorded slightly higher CGVs than the non-arcon variety owing to the precision of jaw movement simulation in the former. However, further studies are required to validate these findings and establish more precise guidelines for the use of CGV measurement protocols in prosthodontic practice.

Effect of Different Lateral Condylar Guidance Registration Methods and Articulators on Bilateral Balanced Occlusion of Complete Denture

Purpose: This study was conducted to accomplish the most balanced occlusion of the complete denture through comparing between lateral condylar guidance angle records of Hanau Equation, Gothic arch tracing and Computed tomography (CBCT) using arcon and non arcon articulators. Materials and methods: Twelve completely edentulous patients were selected for this study, with age ranging from 50-60 years. Selected patients were free from any temporomandibular disorders or dental diseases. Each patient received a complete denture and then duplicated another one for work. With bilateral balanced occlusion concept. The lateral condylar guidance measured using Hanau equation calculated from protrusive interocclusal records, Gothic arch tracer and Cone beam computed tomography. All records transferred to two types of semi-adjustable articulators Hanau non arcon articulator and Bio-art arcon articulator. Denture adjusted on the both articulator system to measure and achieve the bilateral balanced occlusion. Results: In present study comparison between the three methods of right and left lateral condylar guidance registrations Hanau Equation, Cone Beam CT and Gothic arch tracing on both types of articulators shows insignificant difference between right side (p=0.443) and left side (p=0.094) of lateral condylar guidance and also the balanced occlusion values of right and left side on arcon and non arcon semi-adjustable articulator were statically non-significant. Conclusions: Within the outcomes of this study, it could be concluded that to achieve balanced occlusion of complete denture Hanau equation obtained from inter occlusal records with using of Hanau arcon semi-adjustable articulator will be recommended.

Effect of Different Lateral Condylar Guidance Registration Methods and Articulators on Bilateral Balanced Occlusion of Complete Denture

Purpose: This study was conducted to accomplish the most balanced occlusion of the complete denture through comparing between lateral condylar guidance angle records of Hanau Equation, Gothic arch tracing and Computed tomography (CBCT) using arcon and non arcon articulators. Materials and methods: Twelve completely edentulous patients were selected for this study, with age ranging from 50-60 years. Selected patients were free from any temporomandibular disorders or dental diseases. Each patient received a complete denture and then duplicated another one for work. With bilateral balanced occlusion concept. The lateral condylar guidance measured using Hanau equation calculated from protrusive interocclusal records, Gothic arch tracer and Cone beam computed tomography. All records transferred to two types of semi-adjustable articulators Hanau non arcon articulator and Bio-art arcon articulator. Denture adjusted on the both articulator system to measure and achieve the bilateral balanced occlusion. Results: In present study comparison between the three methods of right and left lateral condylar guidance registrations Hanau Equation, Cone Beam CT and Gothic arch tracing on both types of articulators shows insignificant difference between right side (p=0.443) and left side (p=0.094) of lateral condylar guidance and also the balanced occlusion values of right and left side on arcon and non arcon semi-adjustable articulator were statically non-significant. Conclusions: Within the outcomes of this study, it could be concluded that to achieve balanced occlusion of complete denture Hanau equation obtained from inter occlusal records with using of Hanau arcon semi-adjustable articulator will be recommended.

Heading and velocity guidance based path following of autonomous surface vehicle with uncertainty attenuation and asymmetric saturated constraints

The path following of underactuated autonomous surface vehicle (ASV) with line-of-sight (LOS)-based heading and velocity guidance is studied thoroughly in the presence of complex uncertainties and asymmetric input saturation that actuators are likely to suffer from. On the basis of the extended-state-observer-based LOS (ELOS) principle and guided velocity design strategies, a finite-time heading and velocity guidance control (HVG) scheme is presented. Firstly, an improved ELOS (IELOS) is developed such that the unknown sideslip angle can be estimated directly, instead of requiring one more step to calculate it by the output of observers and relying on the equivalent assumption between actual heading angle and guidance angle. Secondly, a new form of velocity guidance is designed by considering magnitude and rate constraints and path’s curvature, keeping in line with ASV’s manoeuvrability and agility. Then asymmetric saturation is considered and studied by designing projection-based finite-time auxiliary systems to avoid parameter drift. All error signals of the closed-loop system of ASV are forced to converge to an arbitrarily small neighbourhood of the origin within a finite settling time by the HVG scheme. The expected performance of the presented strategy is demonstrated via a series of simulations and comparisons. In addition, to show the strong robustness of the presented scheme, stochastic noises modelled by Markov process, bidirectional step signals and faults both multiplication and addition types are considered in simulations.

Complicated Relationships between Anterior and Condylar Guidance and Their Clinical Implications-Comparison by Cone Beam Computed Tomography and Electronic Axiography-An Observational Cohort Cross-Sectional Study.

A complex prosthodontic treatment is believed to be more successful when the condylar path is replicated using the articulator. However, there is an ongoing major disagreement between the researchers as the exact relationship between the posterior and anterior determinants has not been clear. The purpose of this study was to investigate whether the protrusive movement of the mandible does correlate with the temporomandibular joint (TMJ) anatomy or with incised features. Subjects (15 males and 15 females) were qualified for this study based on an initial interview including the following criteria: age 21-23 (+/-1), no history of trauma, orthodontic treatment, or temporomandibular disorders (TMD). For each patient, the angle of the condylar path, incisal guidance angle (IGA), interincisal angle, as well as overbite and overjet were measured on cone beam computed tomography (CBCT). This was followed by the examination with the Modjaw® electronic axiograph recording and calculating the functional sagittal condylar guidance angle (SCGA) for the right and left TMJ during the protrusion. The results show that the mean functional axiographic measurement of SCGA in protrusion significantly correlates with the TMJ anatomy presented on CBCT. Moreover, a significant correlation was found between the values of SCGA in the functional and anatomical measurements in all its variants. It turned out that, statistically, the AB measurement was the most accurate. Finally, results showed that incisal relationships of permanent teeth such as overbite, overjet, incisal guidance angle and interincisal angle do not correlate with TMJ anatomy, and therefore, regarding an analyzed study group, do not affect the TMJ formation in young adults.

Evaluation of accuracy between extraoral Gothic arch tracing and various other methods assessing horizontal condylar guidance angle in completely edentulous patients: A systematic review and meta-analysis.

The aim of this systematic review and meta-analysis was to determine the accuracy of different methods of measuring horizontal condylar guidance (HCG) angle in comparison with extraoral Gothic arch tracing for completely edentulous patients. This was a systematic review and meta-analysis following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Two reviewers searched the EBSCOhost, Cochrane Library, and PubMed/MEDLINE databases and the Google Scholar search engine for in vivo studies, randomized controlled trials, cross-sectional studies, and quasi-experimental studies published from January 2005 to December 2022 on various other methods of determining HCG angle in completely edentulous patients compared with extraoral Gothic arch tracing method. Meta-analysis was conducted from the reported quantitative data. A total of 513 articles were obtained from different electronic databases, of which 22 studies were included for qualitative synthesis and 20 studies were included for meta-analysis. For the right side, a statistically significant difference was observed for panoramic radiograph (P < 0.05, pooled mean difference = 5.08 [2.17, 7]) and cephalogram (P < 0.05, pooled mean difference = 10.65 [8.81, 12.49]), whereas no statistically significant difference was observed for cone-beam computed tomography (CBCT) (P = 0.41, pooled mean difference = 4.39 [-6.10, 14.87]) and protrusive interocclusal wax record (P = 0.92, pooled mean difference = -0.45 [-9.62, 8.72]) as compared with extraoral Gothic arch tracing method. For the left side, a statistically significant difference was observed for panoramic radiograph (P < 0.05, pooled mean difference = 5.07 [1.95, 8.18]) and cephalogram (P < 0.05, pooled mean difference = 10.24 [8.65, 11.83]), whereas no statistically significant difference was observed for CBCT (P = 0.31, pooled mean difference = 4.05 [-3.74, 11.84]) and protrusive interocclusal wax record (P = 0.72, pooled mean difference = -1.21 [-7.86, 5.43]) as compared with extraoral Gothic arch tracing method. The cephalogram and panoramic radiograph obtained higher HCG angles in completely edentulous patients than extraoral Gothic arch tracing.

Comparison of Condylar Inclination Attained by Interocclusal Records, Graphic Tracer and Arcus Digma II and Their Effect on Bilateral Balanced Occlusion

Purpose: Was to compare between the interocclusal record for protrusive movement, the tracing method and the electronic face bow (Arcus Digma) for recording horizontal condylar guidance and their effects on bilateral balanced occlusion. Material and methods: Ten completely edentulous patients with an average age of 55 years old participated in this study. Each patient received upper and lower complete denture, artificial teeth were arranged according to balanced occlusion concept. The horizontal condylar angle was recorded during patient mandibular protrusion of 6mm using the following techniques; interocclusal record, tracer (quick set analyzer) and electronic face bow (Arcus Digma II). Results: The horizontal condylar guidance values of both right and left sides obtained from interocclusal record for protrusive movement, tracing method as well as electronic face bow (Arcus Digma II) showed no statistically significant differences (P>0.05) using ANOVA test (at 95% confidence interval). Arcus Digma II method recorded the centric relation at a more posterior position than other methods, However, it could not make any difference in clinical performance of the complete denture. Horizontal condylar guidance angle was approximately similar by the three techniques. Conclusion: Arcus Digma II seemed a reliable and promising method to be used in recording patient’s horizontal condylar angle as an alternative to the interocclusal and tracer methods.

Comparison of accuracy of protrusive condylar guidance registration by two interocclusal recording materials in edentulous patients.

During complete denture fabrication making Interocclusal records plays an integral role to obtain the condylar guidance value. The study was conducted to compare the protrusive condylar guidance registration by two interocclusal recording materials-Quick setting plaster and Luxabite®(bisacrylic composite) in semi adjustable articulator for completely edentulous patients. Maxillary and Mandibular casts of the completely edentulous patients were mounted in Hanau®Wide Vue articulator. The Quick setting plaster and Luxabite®(bisacrylic composite) was used as interocclusal recording materials to program the protrusive condylar guidance angles in the articulators. The protrusive condylar guidance values registered in the articulator for the different interocclusal records were tabulated and statistically analyzed.. The mean protrusive condylar guidance values registered in the articulator was compared with two parameters obtained from the radiographic tracings -- the protrusive condylar path angle obtained with Quick setting plaster and Luxabite with the inclination of articular eminence to the Frankfort horizontal plane. From the study it was concluded that the Luxabite®(bisacrylic composite) material demonstrated better reproducibility of protrusive condylar guidance registration.than the Quick setting plaster.

Comparative Evaluation Of Clinical And Radiographic Horizontal Condylar Guidance Angle Values By Using Two Different Interocclusal Recording Materials In Dentulous Patients

Introduction: The success of prosthodontic procedures can be accurately determined by the exact replication of the patient’s condylar path using a semi-adjustable articulator. It allows the clinician to determine the morphology of the occlusal surfaces in relation to the condylar pathway during mandibular movements. If condylar guidance is not exactly registered, it might result in occlusal interferences during movements of the mandible and lengthen chairside adjustment time, which is inconvenient for the patient and dentist.Materials and methods: A total of 20 dentulous patients from 20 to 30 years of age group attending the department of prosthodontics at Sibar institute of dental sciences were selected for the study. Alu wax and jet bite were used to obtain the protrusive interocclusal record (PIR). Protrusive records were then used to program the semi-adjustable articulator to obtain HCGA values on both sides. Using the same protrusive records CBCT radiograph was taken. Radiographic images were traced on tracing paper and HCGA values were measured using Frankfort’s horizontal reference line (the line connecting porion and orbitale) and the mean curvature line (most-superior and most-inferior points of the curvatures) on both sides using a protractor. The data were analyzed by paired sample t-tests and Pearson’s correlation tests.Results: There was no significant difference between the right and left sides in the clinical and radiographic methods using Alu wax PIR. In the clinical method utilizing jet bite PIR, the right side had significantly higher HCGA values than on the left side. On CBCT, no such differences were found.Conclusion: CBCT horizontal condylar guidance angle values were higher than those obtained using the clinical method by using both records. Values obtained from both the methods, i.e., protrusive interocclusal record and cone-beam computed tomography, were compared and correlated.

Comparative Analysis of Condylar Guidance Angle Obtained by Protrusive Interocclusal Records and Radiographic Methods in Edentulous Patients: An In Vivo Study

Abstract Purpose To compare between values of condylar inclination obtained by protrusive interocclusal records using extraoral Gothic arch tracing with cone-beam computed tomography (CBCT) scan, and cephalometric and panoramic radiographs in edentulous patients. Materials and Methods Horizontal condylar guidance angle (HCGA) was measured using the extraoral Gothic arch tracing, CBCT, lateral cephalogram, and orthopantomogram (OPG) in 20 patients aged between 40 and 75 years. HCGAs were determined clinically using protrusive interocclusal records and semi-adjustable articulator after extraoral Gothic arch tracing. Radiographically, Frankfort horizontal plane was marked and a straight line joining the superior-most point and the inferior-most point of posterior slope of the articular eminence (AE) was drawn till the two lines met at an intersection. The angle at this intersection depicted the AE inclination and the angle was measured. Statistical analysis was done using analysis of variance test, multiple comparison was done using Tukey test, and the Pearson correlation coefficient was compiled for different study parameters. Result A significant difference in condylar guidance was observed among different methods (p-value &lt; 0.05), and significant positive correlations were observed among condylar guidance measured using distinct parameters. Conclusion It was concluded that horizontal condylar guidance (HCG) values with the radiographic technique were higher than the clinical method. It was observed that mean HCG values were higher by 6.4 degrees in CBCT, 6.7 degrees in OPG, and 9.9 degrees in lateral cephalogram as compared with the clinical value. It was also observed that there was a variation of condylar guidance up to 5 degrees between right and left sides.

Fast Finite-Time Path-Following Control of Unmanned Surface Vehicles with Sideslip Compensation and Time-Varying Disturbances

This paper studies the fast finite-time path following of underactuated unmanned surface vehicles (USV) with sideslip compensation, time-varying disturbances and input saturation. In the guidance module, the fast finite-time predictor-based line-of-sight (FFTPLOS) is proposed to overcome the large guidance angle and high-frequency oscillation and eliminate the sideslip angle with finite time. Then, the robust finite-time feedback control is applied to keep the vehicle following the desired path in the control module, where the reduced-order extended state observers (ROESO) are applied to deal with time-varying disturbances. Additionally, fast finite-time auxiliary dynamic systems with smoothly switching functions (FFTADS-SSF) achieve the saturation constraints on actuators with low consumption. The stability analysis proves that the guidance-control system of USVs is uniformly ultimately bounded stable within finite time. The effectiveness and performance of this proposed scheme are superior to the comparison schemes.