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Journal of Dentistry Aug 2023The aim of this study was to clinically evaluate the accuracy of a digital axiographic recording system in tracing the sagittal condylar inclination.
OBJECTIVES
The aim of this study was to clinically evaluate the accuracy of a digital axiographic recording system in tracing the sagittal condylar inclination.
METHODS
An axiographic examination that records the sagittal condylar path during protrusive/retrusive movement was performed on ten patients. Each subject was registered five different times by two different systems: 1) the Cadiax Gamma Diagnostic 4 computerized system as the control; 2) the Zebris Jaw Motion Analyser+ Optic System as the tested digital axiographic recording system. The records obtained allow to calculate the kinematic terminal transverse horizontal axis and the sagittal condylar inclination (SCI) at 3 and 5 mm along the pro-retrusive path. A linear mixed model was used to analyze if there was a statistically significant difference between the two systems.
RESULTS
The mean left SCI value recorded by Zebris system were 49.81 ± 10.64° at 3 mm, 48.10 ± 11.04° at 5 mm, while the values recorded by Gamma system were 55.16° at 3 mm, 52.18° at 5 mm. The mean right SCI value recorded by Zebris system were 54.53 ± 10.26° at 3 mm, 51.85 ± 8.55° at 5 mm, while the values recorded by Gamma system were 49.68° at 3 mm, 48.23° at 5 mm. Linear mixed model showed no significant statistical difference between the two systems.
CONCLUSIONS
Based on preliminary results, the Zebris Jaw Motion Analyzer+ Optic System demonstrates comparable accuracy to the Cadiax Gamma Diagnostic 4 when measuring sagittal condylar inclination.
CLINICAL SIGNIFICANCE
The digital axiographic recording system enables to evaluate sagittal condylar inclination and to adjust virtual articulators in a digital workflow.
Topics: Humans; Mandibular Condyle; Jaw Relation Record; Movement; Dental Articulators; Biomechanical Phenomena
PubMed: 37331577
DOI: 10.1016/j.jdent.2023.104583 -
The Journal of Contemporary Dental... Sep 2022The aim of this article is to discuss the infection control measures with focus on those related to prosthodontic work.
AIM
The aim of this article is to discuss the infection control measures with focus on those related to prosthodontic work.
BACKGROUND
The risk of transmission of several infectious microorganisms during dental procedures and the increased awareness and knowledge of infectious diseases have led to an increased attention to the importance of infection control. Prosthodontists and dental personnel are exposed directly or indirectly to a significant risk of acquiring healthcare-associated infections.
REVIEW RESULTS
High standards of occupational safety and dental infection control must be applied by dental personnel for the safety of patients and dental healthcare workers. All reusable items (critical and semicritical instruments) that come in contact with the patient's saliva, blood, or mucous membranes must be heat-sterilized. Proper disinfectants should be used to disinfect nonsterilizable instruments (e.g., wax knifes, dental shade plastic mixing spatula, guides, fox bite plane, articulators, and facebows).
CONCLUSION
In prosthodontics, items potentially contaminated with patient's blood and saliva are transported between dental clinics and dental laboratories. Such fluids may contain microorganisms with high potential for transmission of several diseases. Therefore, sterilization and disinfection of all items used during prosthodontic work should be part of infection control protocol in dental care setting.
CLINICAL SIGNIFICANCE
In prosthodontic practice, a strict infection prevention plan should be implemented to minimalize the risk of infectious diseases transmission among prosthodontists, dental office, dental laboratory personnel, and patients.
Topics: Humans; Prosthodontics; Dental Clinics; Infection Control; Sterilization; Disinfection; Communicable Diseases; Infection Control, Dental
PubMed: 37283004
DOI: 10.5005/jp-journals-10024-3305 -
Hua Xi Kou Qiang Yi Xue Za Zhi = Huaxi... Jun 2023This study aimed to compare the effects of virtual adjustment on occlusal interferences in mandibular posterior single crown and three-unit bridge restorations by using... (Comparative Study)
Comparative Study
OBJECTIVES
This study aimed to compare the effects of virtual adjustment on occlusal interferences in mandibular posterior single crown and three-unit bridge restorations by using the mandibular movement track and the movement parameters of a virtual articulator.
METHODS
Twenty-two participants were recruited. Digital casts of the maxillary and mandibular arches were obtained using an intraoral scanner, and the jaw registration system was used to record the data of the mandibular movement track and the movement parameters of the articulator. Four kinds of restorations with 0.3 mm occlusal interferences were designed with dental design software. In particular, single crowns were designed for teeth 44 and 46, whereas three-unit bridges were designed for teeth 44-46 and 45-47, and the corresponding natural teeth were virtually extracted. Virtual adjustment of the restorations was performed using two dynamic occlusal recordings, namely, the mandibular movement track and the movement parameters of the virtual articulator. A reverse-engineering software was used to measure the root-mean-square of the three-dimensional deviation of the occlusal surfaces between natural teeth and the adjusted restorations. The differences between the two methods of virtual-occlusion adjustment were compared and analyzed.
RESULTS
For the same group of restorations, the three-dimensional deviation of the mandibular movement track group were lower than those of the virtual articulator group, and the differences were statistically significant (<0.05). For the four groups of restorations adjusted by the same method, the three-dimensional deviation of the 46-tooth single crown was the largest and the smallest three-dimensional deviation was that of the 44-tooth single crown. Statistical differences existed between the 44-tooth single crown and the other groups (<0.05).
CONCLUSIONS
For the occlusal design of posterior single crown and three-unit bridge, the mandibular movement track could be a more effective approach to virtual occlusal adjustment than the movement parameters of the virtual articulator.
Topics: Humans; Mouth, Edentulous; Occlusal Adjustment; Jaw Relation Record; Dental Articulators; Software
PubMed: 37277790
DOI: 10.7518/hxkq.2023.2022452 -
The Journal of Contemporary Dental... Feb 2023The aim of the present study was to evaluate labiopalatal angulation of maxillary anterior teeth using Custom-made jig, Profile projector, and ImageJ computer software...
AIM
The aim of the present study was to evaluate labiopalatal angulation of maxillary anterior teeth using Custom-made jig, Profile projector, and ImageJ computer software methods.
MATERIALS AND METHODS
The subjects for this study were selected in the age-group of 20-30 years having permanent dentition, including 2nd molars and bilateral Angle's class 1 molar and canine relationship. Recording the labiopalatal angulation in proximal view was carried out by using one manual method and two digital methods namely using Custom-made jig, Profile projector, and ImageJ computer software, respectively. Alginate impressions were made for the subjects, and the spatial relationship of the maxilla to the cranium was recorded using a facebow. The casts were mounted in a semi-adjustable articulator, and the articulated mounted casts with the mounting ring were transferred to the Custom-made jig, and angulations were measured in proximal view. Digital methods of measurement were recorded by using Profile projector and ImageJ computer software methods. Data were tabulated and statistically analyzed.
RESULTS
In males, the mean labiopalatal angulation of maxillary right and left maxillary canines of Custom-made jig was 91.94 ± 1.47 and 91.70 ± 1.68, in Profile projector method 87.41 ± 3.75 and 87.58 ± 3.79, and in ImageJ computer software 84.23 ± 5.72 and 83.29 ± 6.74, respectively. In females, Custom-made jig was 91.82 ± 1.55 and 92.17 ± 1.84, in Profile projector method 86.70 ± 5.58 and 86.94 ± 5.57, and in ImageJ computer software 82.76 ± 6.34 and 83.05 ± 6.12, respectively. There was a very high statistically significant difference found between different methods.
CONCLUSION
In conclusion, the values obtained in the digital methods (i.e., both the Profile projector and ImageJ computer software) were more accurate than the manual method. However, the ImageJ computer software was most reliable in comparison with the values obtained in Profile projector.
CLINICAL SIGNIFICANCE
The labiopalatal angulation of anterior teeth will act as a guideline in re-establishing the correct angulations and the anatomic contours of the maxillary arch to achieve the desired esthetics that provide adequate lip support and to restore the required functions.
Topics: Male; Female; Animals; Esthetics, Dental; Tooth; Molar; Software; Maxilla
PubMed: 37272142
DOI: 10.5005/jp-journals-10024-3431 -
Clinical Oral Investigations Jul 2023This clinical study aimed to compare the performance of various virtual articulator (VA) mounting procedures in the participants' natural head position (NHP).
OBJECTIVES
This clinical study aimed to compare the performance of various virtual articulator (VA) mounting procedures in the participants' natural head position (NHP).
MATERIALS AND METHODS
Fourteen participants with acceptable dentitions and jaw relationships were recruited in this study registered in the Clinical Trials Registry (#NCT05512455; August 2022). A virtual facebow was designed for virtual mounting and hinge axis measurement. Intraoral scans were obtained, and landmarks were placed on each participant's face to register the horizontal plane in NHP. Six virtual mounting procedures were performed for each participant. The average facebow group (AFG) used an indirect digital procedure by using the average facebow record. The average mounting group (AMG) aligned virtual arch models to VA's average occlusal plane. The smartphone facial scan group (SFG) and professional facial scan group (PFG) used facial scan images with Beyron points and horizontal landmarks, respectively. The cone-beam computed tomography (CBCT) scan group (CTG) used the condyle medial pole, and horizontal landmarks were applied. The kinematic facebow group (KFG) served as the control group, and a direct digital procedure was applied using a kinematic digital facebow and the 3D skull model. Deviations of the reference plane and the hinge axis between the KFG and other groups were calculated. The inter-observer variability in virtual mounting software operation was then evaluated using the interclass correlation coefficient (ICC) test.
RESULTS
In virtual condylar center deviations, the CTG had the lowest condylar deviations. The AFG showed larger condylar deviations than PFG, SFG, and CTG. There was no statistically significant difference between the AFG and the AMG and between the PFG and the SFG. In reference plane deviations, the AMG showed the largest angular deviation (8.23 ± 3.29°), and the AFG was 3.89 ± 2.25°. The angular deviations of PFG, SFG, and CTG were very small (means of each group < 1.00°), and there was no significant difference among them. There was no significant difference between the researchers, and the ICC test showed moderate to excellent reliability for the virtual condylar center and good to excellent reliability for the reference plane in the operation of the virtual mounting software.
CONCLUSIONS
CBCT scan provided the lowest hinge axis deviation in virtual mounting compared to average mounting, facebow record, and facial scans. The performance of the smartphone facial scanner in virtual mounting was similar to that of the professional facial scanner. Direct virtual mounting procedures using horizontal landmarks in NHP accurately recorded the horizontal plane.
CLINICAL RELEVANCE
Direct digital procedures can be reliably used for virtual articulator mounting. The use of a smartphone facial scanner provides a suitable and radiation-free option for clinicians.
Topics: Humans; Dental Articulators; Dental Occlusion; Jaw Relation Record; Maxilla; Reproducibility of Results
PubMed: 37247089
DOI: 10.1007/s00784-023-05028-9 -
The Journal of Prosthetic Dentistry May 2023Some contemporary articulator systems claim to be highly precise in their interchangeability, with tolerances below 10 μm in vertical error; however, the claims have...
STATEMENT OF PROBLEM
Some contemporary articulator systems claim to be highly precise in their interchangeability, with tolerances below 10 μm in vertical error; however, the claims have not been independently verified.
PURPOSE
The purpose of this study was to investigate the interchangeability of calibrated semiadjustable articulators in service over time.
MATERIAL AND METHODS
A calibrated mounting articulator served as the master articulator, while the test groups were used articulators with a minimum of 1-year use by predoctoral dental students (n=10); used articulators with a minimum of 1-year use by prosthodontic residents (n=10); and new articulators (n=10). One set of mounted maxillary and mandibular master models was positioned in the master and test articulators. High-precision reference markers on the master models were used to determine interarch 3D distance distortions (dR, dR, and dR), interocclusal 3D distance distortion (dR), interocclusal 2D distance distortions (dx, dy, and dz), and interocclusal angular distortion (dθ) relative to the master articulator. All measurements were conducted three times using a coordinate measuring machine and then averaged to derive the final data set.
RESULTS
For interarch 3D distance distortion, the mean dR ranged from 4.6 ±21.6 μm for new articulators to 56.3 ±47.6 μm for articulators used by prosthodontic residents; mean dR ranged from 65 ±48.6 μm for new articulators to 119.0 ±58.8 μm for articulators used by prosthodontic residents; and mean dR ranged from 12.7 ±39.7 μm for articulators used by prosthodontic residents to 62.8 ±75.2 μm for new articulators. For interocclusal 3D distance distortion, the mean dR ranged from 21.5 ±49.8 μm for new articulators to 68.6 ±64.9 μm for articulators used by predoctoral dental students. For the 2D distance distortions, the mean dx ranged from -17.9 ±43.4 μm for articulators used by predoctoral dental students to -61.9 ±48.3 μm for articulators used by prosthodontic residents; mean dy ranged from 18.1 ±59.4 μm for new articulators to 69.3 ±115.1 μm for articulators used by prosthodontic residents; and mean dz ranged from 29.5 ±20.2 μm for new articulators to 70.1 ±37.8 μm for articulators used by prosthodontic residents. Mean dθ ranged from -0.018 ±0.289 degree for new articulators to 0.141 ±0.267 degree for articulators used by prosthodontic residents. One-way ANOVA by articulator type revealed statistically significant differences among the test groups for dR (P=.007) and dz (P=.011) only, where articulators used by prosthodontic residents fared significantly poorer than the other test groups.
CONCLUSIONS
The new and used articulators tested did not fulfill the manufacturer's claim of accuracy of up to 10 μm in the vertical dimension. Up to 1 year of time in service, none of the investigated test groups fulfilled the criterion for articulator interchangeability, even if the more lenient threshold of 166 μm were accepted.
PubMed: 37244795
DOI: 10.1016/j.prosdent.2023.04.009 -
Journal of Prosthodontics : Official... Feb 2024This paper presents a method for the digital transfer of the upper maxillary arch position using a facebow, a transfer table, and a reference block with a CAD...
This paper presents a method for the digital transfer of the upper maxillary arch position using a facebow, a transfer table, and a reference block with a CAD application without requiring physical casts mounted with articulating gypsum. This technique facilitates the prosthetic digital workflow when the impression is made via intraoral scanning, to obtain the placement of the maxillary arch in the anatomical reference planes and in relation to the axes of rotation of the mandibular movements.
Topics: Dental Articulators; Mandible; Maxilla; Workflow; Computer-Aided Design
PubMed: 37209310
DOI: 10.1111/jopr.13703 -
European Journal of Dental Education :... Feb 2024This study evaluated the self-assessment skills of third-year dental students regarding their performance in complete removable prosthodontics (CRP) preclinical course.
INTRODUCTION
This study evaluated the self-assessment skills of third-year dental students regarding their performance in complete removable prosthodontics (CRP) preclinical course.
METHODS AND MATERIALS
This cross-sectional study was conducted on all third-year dental students attending the International Dental College of Tehran University of Medical Sciences. The students were requested to self-assess their performance in primary impression making, custom tray fabrication, border moulding, final impression making, master cast fabrication, record-base fabrication and tooth arrangement in CRP preclinical course. The performance of dental students in each step was scored by themselves and their mentors. Data were analysed by the Mann-Whitney U, Pearson's correlation and t-tests (α = 0.05).
RESULTS
Totally 25 male (55.6%) and 20 female (44.4%) dental students were evaluated. Significant differences were noted between male and female dental students in self-assessment scores regarding adequate extension of the custom tray (p = .027), the correct position of tray handle (p = .020), visibility of vestibular width and depth on the cast (p = .011), the coincidence of upper and lower midlines (p = .005) and correct orientation of maxillary and mandibular planes in the articulator (p = .036). The mean self-assessment score of female students was significantly higher than that of male students (p = .01). The scores given by the mentors were not significantly different for male and female students (p = .975). The difference between the self-assessment score of students and the mentor score was not significant (p = .067) either in males or in females (p > .05).
CONCLUSION
Undergraduate dental students favourably self-assessed their performance in all steps of the preclinical course of CRP, comparable with their mentor assessment.
Topics: Humans; Male; Female; Self-Assessment; Students, Dental; Prosthodontics; Cross-Sectional Studies; Education, Dental; Iran
PubMed: 37145242
DOI: 10.1111/eje.12909 -
Clinical Oral Investigations Jul 2023This study aimed to compare the accuracy of occlusal registration for single-unit restorations in the posterior area of the jaw using the complete-arch or quadrant scan...
OBJECTIVE
This study aimed to compare the accuracy of occlusal registration for single-unit restorations in the posterior area of the jaw using the complete-arch or quadrant scan techniques.
MATERIALS AND METHODS
A master cast was prepared and articulated on a nonadjustable articulator, and the maxillary left first molar was prepared for a full-coverage crown. The master cast was digitized as the reference data using a laboratory scanner (E3 scanner, 3Shape, Copenhagen, Denmark). It was scanned 10 times in the complete arch and 10 times in the quadrant, with an occlusal registration in each, using four intraoral scanners (i500, Primescan, TRIOS 3, and TRIOS 4). The scanned data were aligned to the reference data using GOM Inspect software. A three-dimensional analysis of the surface-based occlusal clearance and angular deviation, focusing on the prepared tooth, was performed.
RESULTS
The mean surface-based occlusal clearance in the quadrant and complete-arch scans was 1.622 ± 0.032 mm and 1.642 ± 0.043 mm, respectively. Angular deviations compared to the reference cast showed a difference of 0.10° distally and 0.09° buccally for the quadrant scan and 0.12° distally and buccally for the complete-arch scan. Statistical analysis was performed using one-way analysis of variance and post hoc Scheffe's test. No significant differences were observed between the test groups.
CONCLUSIONS
No significant differences were found between occlusal registrations of the complete-arch and quadrant scans. Therefore, a quadrant scan can achieve the same outcome as a complete-arch scan for single-unit restoration in the posterior area of the jaw.
CLINICAL RELEVANCE
Quadrant scanning for single-unit restoration showed similar outcomes as complete-arch scans.
Topics: Humans; Imaging, Three-Dimensional; Dental Impression Technique; Models, Dental; Software; Tooth; Computer-Aided Design; Dental Arch
PubMed: 37039957
DOI: 10.1007/s00784-023-04993-5 -
The Journal of Prosthetic Dentistry Jun 2023Digital occlusal analyzers allow the recording of dental contact forces. Some authors assume a unique location for the center of contact forces at the position of...
STATEMENT OF PROBLEM
Digital occlusal analyzers allow the recording of dental contact forces. Some authors assume a unique location for the center of contact forces at the position of maximum intercuspation, while others indicate variations in dental contact forces when recorded at different times of the day. Which approach is more appropriate is unclear.
PURPOSE
The purpose of this in vitro study was to analyze whether a change in the balance of masticatory forces influences the location of the center of contact forces and its magnitude.
MATERIAL AND METHODS
Three different dental casts, selected under dental criteria, were mounted in maximum intercuspation on a semiadjustable articulator equipped with a pattern indicating 9 different force application points (intersection point between 3 longitudinal rows and 3 transverse columns). A force of constant magnitude (169 N) was applied 10 times at each of the application points, and occlusal forces were recorded with a digital occlusal analyzer. Then, two variables were studied: the location of the center of contact forces and its magnitude. Each force application position (9 positions × 3 dental casts=27 in total) was repeated 10 times, and measured data were statistically analyzed with 2-way repeated measures ANOVA (α=.05) test.
RESULTS
The repeatability of the method indicated that the coefficient of variation mean was 0.37% in the location of the center of contact forces and that its magnitude was 3.70%. The 2-way repeated measures ANOVA test revealed statistically significant variations in the location of the center of contact forces and its magnitude, revealing that longitudinal changes of the application point of masticatory forces affected the magnitude of contact forces and that longitudinal and transverse changes of the application point of masticatory forces affected the location of the center of contact forces.
CONCLUSIONS
The location of the center of contact force and its magnitude provided by a digital occlusal analyzer at the position of maximum intercuspation are not necessarily unique to each articulated dental cast. Even if the intensity of the masticatory force remains unchanged, changes in its lateral or longitudinal balance also influence the result of the occlusion forces.
Topics: Bite Force; Dental Occlusion; Dental Articulators
PubMed: 37003941
DOI: 10.1016/j.prosdent.2023.03.007