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Journal of Pharmacy & Bioallied Sciences Jun 2021Various clinical methods for recording the condylar guidance (CG) are the intraoral check bite method, graphic tracings, and functional recordings. Accuracy of graphic...
BACKGROUND
Various clinical methods for recording the condylar guidance (CG) are the intraoral check bite method, graphic tracings, and functional recordings. Accuracy of graphic tracings is affected by patient-related factors such as neuromuscular control of the individual, stability of record bases as well as stability of recording media. The current recommended average settings using Hanau's formula questionable, and thus reassessment is needed.
PURPOSE
The purpose of this study is to use radiographic technique to determine the lateral CG and compare these values with those obtained using Hanau's formula and to evaluate whether there are differences between the right and left paths of the condyles.
MATERIALS AND METHODS
Twenty completely edentulous patients were selected. Articulator was modified with sectioned protractor for obtaining per degree interval calibration. With the protrusive records, the horizontal CG (H) was adjusted and the Bennett's angle (LCG-C) was calculated using the formula. With the tracing device in the mouth, sub-mento vertex projection radiographs were obtained. Each radiograph was traced and superimposed for Bennett angle determination (LCG-M).
RESULTS
The median (interquartile range [IQR]) of right and left LCG-C were 15.45 (0.8) and 15.50 (0.7), respectively. The median (IQR) of right and left LCG-M were 37.00 (6.0) and 36.50 (6.8), respectively. A statistically significant difference exists between LCG-C and LCG-M. Both LCG-C and-M values exhibited no variations on both sides.
CONCLUSIONS
Radiographic technique yielded an amplified LCG when compared to the value obtained by Hanau's formula.
PubMed: 34447149
DOI: 10.4103/jpbs.JPBS_640_20 -
Journal of Oral Biology and... 2015This study evaluated the teeth movement in maxillary dentures and mandibular implantsupported prostheses processed by microwave flasks.
BACKGROUND/AIMS
This study evaluated the teeth movement in maxillary dentures and mandibular implantsupported prostheses processed by microwave flasks.
METHODS
A model mounted on articulator was used to manufacture Co-Cr frameworks. Pins were placed for measurements on the incisal edge of upper and lower central incisors (I), buccal cusp of first upper and lower premolars (PM), and mesiobuccal cusps of upper and lower second molars (M). Distances I-I (incisor to incisor), PM-PM (premolar to premolar), M-M (molar to molar), RI-RM (right incisor to right molar), and LI-LM (left incisor to left molar) were measured before and after processing using a microscope (0.0005 mm). Vertical misfit between abutment and implant platform was evaluated for regions A (left distal implant), B (left median implant), C (medial implant), D (right median implant), and E (right distal implant) in predetermined labial and lingual sites. Prostheses were divided into groups G1 - conventional flask, and G2 - experimental HH flask. Acrylic resin was microwaved at 1400 W (30% for 3 min, 0% for 3 min, and 60% for 3 min). Horizontal teeth displacement and vertical misfit between abutment and implant platform were considered before and after procedures. Data were submitted to three-way ANOVA and Tukey's test (α = 0.05).
RESULTS
Except for M-M distance, the teeth showed displacements without statistical difference for prosthesis and flask factors. There was no significant difference for vertical misfit values for both flasks.
CONCLUSION
Diferente flasks did not cause significant changes in the teeth displacement, except for M-M. Vertical misfit values were not influenced by the flasks.
PubMed: 26605143
DOI: 10.1016/j.jobcr.2015.06.001 -
The Angle Orthodontist Mar 2012To determine the influence of the occlusal plane angle on smile attractiveness as perceived by a group of adult orthodontic patients and dentists. (Comparative Study)
Comparative Study
OBJECTIVE
To determine the influence of the occlusal plane angle on smile attractiveness as perceived by a group of adult orthodontic patients and dentists.
MATERIALS AND METHODS
The first stage utilized a laboratory approach to record changes in vertical tooth position at different occlusal plane angles using a maxillary model mounted on an articulator. In the second stage, photographic manipulation was undertaken, using data from stage 1, to produce a computerized prediction of the appearance of the smile at differing occlusal plane angles (0, 5, 10, 15, and 20 degrees). Finally, the five developed photographs were assessed by participants.
RESULTS
Alterations in the occlusal plane angle did affect relative smile attractiveness for both patients (n = 66) and dentists (n = 66). For patients, the 10 degree smile was rated better than the 0 and 20 degree smiles (P < .01); for dentists, the 15 degree smile was rated better than the 0 and 20 degree smiles (P < .01). The 5, 10, and 15 degree smiles were indistinguishable for patients, and the 10 and 15 degree smiles were indistinguishable for dentists.
CONCLUSION
Changing the occlusal plane angle does affect relative smile attractiveness. However, patients were more tolerant of these changes than dentists. This suggests that large changes in the occlusal plane angle would affect relative smile attractiveness, and small changes are unlikely to affect smile attractiveness.
Topics: Adult; Attitude of Health Personnel; Attitude to Health; Dental Articulators; Dental Occlusion; Dentists; Esthetics, Dental; Female; Humans; Male; Maxilla; Models, Dental; Photography, Dental; Smiling; Tooth
PubMed: 21932940
DOI: 10.2319/050411-318.1 -
Journal of Oral Science Dec 2018To evaluate the occlusion accuracy of a novel impression technique, excessively high occlusion and the occlusal contact area during lateral movements were compared... (Comparative Study)
Comparative Study
To evaluate the occlusion accuracy of a novel impression technique, excessively high occlusion and the occlusal contact area during lateral movements were compared between metal restorations (restorations) and removable partial dentures (RPDs) fabricated using conventional and novel techniques. Both restorations and RPDs were fabricated on the simulation model with the precise displacement of the remaining teeth and soft tissue. For the novel technique, functionally generated path (FGP) recording and impression under occlusal force were simultaneously performed using a custom tray with an FGP table. For the two conventional techniques, definitive casts were mounted on an average value articulator and a semi-adjustable articulator in the typical manner. Prostheses were placed on the simulation models, and excessively high occlusion in the intercuspal position and occlusal contact areas during lateral movements were measured. Statistical analyses were performed using Kruskal-Wallis and Steel-Dwass tests (α = 0.05). For both prostheses, conventional techniques showed significantly higher occlusion in the intercuspal position than the novel technique. Moreover, the new technique demonstrated better guidance contact during lateral movements than conventional techniques. This novel technique can be recommended for the fabrication of highly accurate prostheses with appropriate occlusal contact without corrections at delivery.
Topics: Bite Force; Computer-Aided Design; Dental Impression Technique; Dental Materials; Dental Restoration, Permanent; Denture Design; Denture, Partial, Removable; Humans; Occlusal Adjustment
PubMed: 30158340
DOI: 10.2334/josnusd.17-0461 -
Sensors (Basel, Switzerland) Feb 2022Automatic feature extraction from images of speech articulators is currently achieved by detecting edges. Here, we investigate the use of pose estimation deep neural...
Automatic feature extraction from images of speech articulators is currently achieved by detecting edges. Here, we investigate the use of pose estimation deep neural nets with transfer learning to perform markerless estimation of speech articulator keypoints using only a few hundred hand-labelled images as training input. Midsagittal ultrasound images of the tongue, jaw, and hyoid and camera images of the lips were hand-labelled with keypoints, trained using DeepLabCut and evaluated on unseen speakers and systems. Tongue surface contours interpolated from estimated and hand-labelled keypoints produced an average mean sum of distances (MSD) of 0.93, s.d. 0.46 mm, compared with 0.96, s.d. 0.39 mm, for two human labellers, and 2.3, s.d. 1.5 mm, for the best performing edge detection algorithm. A pilot set of simultaneous electromagnetic articulography (EMA) and ultrasound recordings demonstrated partial correlation among three physical sensor positions and the corresponding estimated keypoints and requires further investigation. The accuracy of the estimating lip aperture from a camera video was high, with a mean MSD of 0.70, s.d. 0.56 mm compared with 0.57, s.d. 0.48 mm for two human labellers. DeepLabCut was found to be a fast, accurate and fully automatic method of providing unique kinematic data for tongue, hyoid, jaw, and lips.
Topics: Biomechanical Phenomena; Dental Articulators; Humans; Jaw; Lip; Speech; Tongue
PubMed: 35161879
DOI: 10.3390/s22031133 -
Beijing Da Xue Xue Bao. Yi Xue Ban =... Feb 2024To compare the trueness of incisal guidance of implant-supported single crowns designed by patient-specific motion (PSM) with that designed by average-value virtual...
OBJECTIVE
To compare the trueness of incisal guidance of implant-supported single crowns designed by patient-specific motion (PSM) with that designed by average-value virtual articulator (AVA).
METHODS
The study had recruited 12 participants with complete dentition and stable incisal guidance. An intraoral scanner was used to scan digital casts and record two types of patient-specific motion (data only including protrusive movement, and data including protrusive movement and lateral protrusive movement). The lingual surfaces of the maxillary incisors which guided the protrusive movement was selected and elevated to create a reference cast. A maxillary central incisor of original casts was vir-tually extracted and implanted to generate a working cast. The Dental system software program was used to design implant-supported single crowns with the anatomical coping design method. The incisal guidance was designed by different methods. The incisal guidance in control group was designed by the average-value virtual articulator. The incisal guidance in experiment groups was designed by the patient-specific motion only including protrusive movement (PSM1) and with the patient-specific motion including protrusive movement and lateral protrusive movement (PSM2). The incisal guidance of prosthesis designed by these 3 methods were compared with the original incisal guidance in Geomagic Control 2015 (3DSystem, America). The measurements included: Average of positive values, ratio of positive area and maximum value reflecting supra-occlusion; average of negative values, ratio of negative area and minimum value reflecting over-correction; and root mean square reflecting overall deviation.
RESULTS
Statistical data were collected using the median (interquartile range) method. The average of positive values, ratio of positive area and average of negative values of the PSM2 group were smaller than those of the control group [8.0 (18.8) μm . 37.5 (47.5) μm; 0 . 7.2% (38.1%); -109.0 (63.8) μm .-66.5 (64.5) μm], and the ratio of negative area of PSM2 group was larger than those of the control group [52.9% (47.8%) . 17.3% (45.3%)], with significant differences ( all < 0.05). The ratio of positive area [0.1% (7.0%)] and average of negative values [-97.0 (61.5) μm] of PSM1 group, were smaller than those of the control group, and the ratio of negative area [40.7% (39.2%)] of the PSM1 group was larger than that of the control group, with significant differences ( < 0.05). The average of positive values [20.0 (42.0) μm] and ratio of positive area of PSM1 group was larger than that of the PSM2 group with significant differences ( < 0.05).
CONCLUSION
To establish the incisor guidance of implant-supported single crowns, compared with the average-value virtual articulator and the patient-specific motion only including protrusive movement, the patient-specific motion including protrusive movement and lateral protrusive movement is more conducive to reducing the protrusive interference of prosthesis and improving the occlusal fit.
Topics: Humans; Incisor; Software; Maxilla; Crowns; Movement; Computer-Aided Design
PubMed: 38318900
DOI: 10.19723/j.issn.1671-167X.2024.01.013 -
Anatomical Record (Hoboken, N.J. : 2007) May 2012The position of dental wear facets depends on crown morphology, antagonistic relation, and occlusal movements. The correspondence between specific directions of...
The position of dental wear facets depends on crown morphology, antagonistic relation, and occlusal movements. The correspondence between specific directions of movements and the position of wear facets cannot be easily evaluated in vivo and has never been tested experimentally. An experimental analysis was carried out to provide evidence that explicit occlusal movements are responsible for the spatial position of wears facets. Unworn dental stone replicas of modern human prosthetic molar were mounted in a physical dental articulator, and the upper dental arch was ground against the lowers to create a wear facet pattern. The relief guided movements were constrained sequentially by means of three different condyle box setups: (1) experienced-based mean values for sagittal condyle inclination, lateroretrusion, Benett angle, and transversal condyle inclination were used; (2) pure retrusion and immediate side shift movements were added; (3) retrusion and immediate side shift were increased. Finally, the upper and lower first molars were surface scanned and macrowear facets were quantified in four wear stages. The results show that a wear facet pattern was created similar to what is seen on human molars in vivo occlusion. Some facets only developed if specific directions of movement were carried out. Therefore, we posit that an analysis of wear facet patterns is useful in recreating the individual occlusal movements. This information can be used not only to guide reproducible functional reconstructions of crown relief and dental arches but also to deduce jaw movements when, for example, isolated primate teeth are discovered in paleontological contexts.
Topics: Crowns; Dental Occlusion; Humans; Mastication; Models, Anatomic; Molar; Prosthesis Design; Stress, Mechanical; Surface Properties; Tooth Crown; Tooth Wear
PubMed: 22419654
DOI: 10.1002/ar.22440 -
Journal of Indian Prosthodontic Society 2017Many authors have conducted studies that determine horizontal condylar guidance (HCG) using various methods, articulator systems, and recording materials. However, there...
CONTEXT
Many authors have conducted studies that determine horizontal condylar guidance (HCG) using various methods, articulator systems, and recording materials. However, there is a dearth of literature on variability existing in HCG in individuals with different skeletal relationships. This study is an attempt to verify whether such a difference exists or not.
AIMS
The aim of this study is to determine and correlate the HCG in individuals with Angle's Class I, Class II, and Class III malocclusion using radiographic and clinical methods.
SETTINGS AND DESIGN
HCG was recorded for thirty individuals, ten of each class. For each individual, HCG was recorded clinically as well as radiographically.
SUBJECTS AND METHODS
Clinically, HCG was recorded using protrusive check bites and a semi-adjustable articulator. Radiographically, two methods were employed. First, a "tangent method" wherein the angle made by a tangent to the posterior slope of articular eminence with the Frankfurt horizontal (FH) plane was considered as the HCG, and second, a "protrusive method" where the position of the condyle at maximum intercuspation and 6 mm protrusion were traced, and the angle this path made with the FH plane was recorded as the HCG.
STATISTICAL ANALYSIS
Descriptive statistical analysis along with Tukey's test and analysis of variance was used to calculate and compare the mean values. Pearson correlation coefficient was used to establish correlation between various means.
RESULTS
A significant difference in the HCG of three skeletal relationships was seen, with Class II having a steeper angle than the other two. Among the various methods used, a correlation was found between the clinical and the protrusive method; however, the tangent method yielded greater values of HCG.
CONCLUSIONS
The average value of HCG should not be used as it differs according to the skeletal relationship. Radiographic method can be used to yield consistent HCG; however, the protrusive method should be employed.
PubMed: 28584419
DOI: 10.4103/jips.jips_290_16 -
Journal of Pharmacy & Bioallied Sciences Feb 2024This research study aimed to evaluate and compare the capability of four various bite registration materials to reproduce precise interocclusal relationships in the...
BACKGROUND
This research study aimed to evaluate and compare the capability of four various bite registration materials to reproduce precise interocclusal relationships in the vertical dimension.
MATERIALS AND METHODS
Ideal maxillary and mandibular casts were mounted on the semi-adjustable articulator in maximum intercuspation after mock tooth preparation on 46, 47, and 48. Models were scanned by the Medit T500 Dental Lab Scanner, and initial reading was noted at the predetermined points. Ten interocclusal bite registrations were made using four materials (CADbite, Jet Bite, Ramitec, and Aluwax). The mandibular model was demounted and again remounted using the interocclusal records, and the final reading was noted after scanning.
RESULTS
Ramitec showed superior results when compared to polyvinyl bite registration material and Aluwax, but the differences between Ramitec, CADbite, and Jet Bite were nonsignificant.
CONCLUSIONS
Although all four materials are suitable for clinical use, elastomeric materials showed superior results. In that, polyether was found to be the best.
PubMed: 38595573
DOI: 10.4103/jpbs.jpbs_990_23 -
Journal of Indian Prosthodontic Society 2019The aim of the study was to compare two radiographic techniques, orthopantomograph (OPG), and cone-beam computed tomography (CBCT) in determining the sagittal condylar...
Comparative evaluation of condylar inclination in dentulous subjects as determined by two radiographic methods: Orthopantomograph and cone-beam computed tomography - An study.
AIM
The aim of the study was to compare two radiographic techniques, orthopantomograph (OPG), and cone-beam computed tomography (CBCT) in determining the sagittal condylar guidance (SCG) and to find out if CBCT can serve as an alternative aid to program semi-adjustable and fully adjustable articulators.
MATERIALS AND METHODS
Following the inclusion and exclusion criteria, 40 individuals (20 males and 20 females) aged between 20 and 40 years were selected. An OPG and a CBCT radiograph were obtained for each individual. Using appropriate software, the SCG was measured for both the sides, for both the radiographic methods. The values for each individual were obtained by two investigators for both the methods using the respective software and the average value was taken. After performing the Shapiro-Wilk test, paired -test was used to compare the mean difference pairwise (for both right and left side) while -test was used to compare the mean difference between two groups.
RESULTS
Results showed that the right and left SCG values obtained from both, OPG and CBCT methods were comparable and there were no significant differences. Statistically significant difference was not found between the left and ride side condylar inclination values for both the sex obtained from both the methods. With increasing age, condylar inclination values obtained from both the radiographic methods tend to decrease. The values for SCG obtained from both the methods (CBCT and OPG) are thus comparable and correlated.
CONCLUSION
The values for SCG obtained from both the methods (CBCT and OPG) are comparable and correlated. Thus, CBCT being a better radiographic technique can be used for obtaining the condylar inclination for programming the semi-adjustable and fully adjustable dental articulators.
PubMed: 31040544
DOI: 10.4103/jips.jips_266_18