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The Journal of Prosthetic Dentistry Apr 2024The alignment of the maxillary and mandibular digital scans obtained with an intraoral scanner (IOS) generates digital interocclusal records. Although the accuracy of...
STATEMENT OF PROBLEM
The alignment of the maxillary and mandibular digital scans obtained with an intraoral scanner (IOS) generates digital interocclusal records. Although the accuracy of maxillary and mandibular digital scans obtained from an IOS is widely studied, the accuracy of digital interocclusal records obtained with them is not; even less studied is the accuracy (trueness and precision) of the alignment methods that are available to obtain them.
PURPOSE
The purpose of this in vitro study was to assess the precision under repeatability conditions (repeatability) of the different alignment methods used to obtain digital interocclusal records.
MATERIAL AND METHODS
Digital scans of maxillary and mandibular casts of a dentate healthy adult were acquired with an IOS. Casts were then mounted in maximum intercuspal position in a semi-adjustable mechanical articulator (1801 AR Model PSH Articulator), and left and right occlusal digital scans were acquired with the IOS. Occlusal digital scans were repeated 7 times under repeatability conditions. After obtaining each pair of occlusal digital scans, the software program of the IOS automatically aligned the maxillary and mandibular digital scans with occlusal digital scans (TRI method), resulting in 7 digital interocclusal records composed of aligned maxillary and mandibular digital scans and occlusal digital scans. All 7 sets of aligned digital scans were exported and realigned in a dental computer-aided design software program by means of global and reference alignment methods (EXO-B and EXO-R methods, respectively). To assess the repeatability, the 7 aligned digital scan sets of each group were repositioned in the common coordinate system by aligning maxillary digital scans, and repeatability was calculated in terms of the distance between the vertices of the mandibular digital scans for each of the possible nonrepeating combinations of pairs (C=21). The repeatability was tested by using the Kruskal-Wallis test for nonparametric distribution followed by the Mann-Whitney U test and Bonferroni correction for pairwise comparisons (α=.05).
RESULTS
The median with interquartile range for the TRI alignment method was 47 (27) μm for the EXO-B method 41 (25) μm and 16 (5) μm for EXO-R. The Kruskal-Wallis test showed statistical difference between test groups (P<.05). The post hoc Dunn test with Bonferroni adjustment detected significant statistical differences between the EXO-R-TRI (P<.001) and EXO-R-EXO-B (P<.001) alignment methods.
CONCLUSIONS
This study found that the alignment method could influence the repeatability of digital interocclusal records. The reference best-fit alignment method (EXO-R) provided better repeatability.
Topics: Imaging, Three-Dimensional; Models, Dental; Dental Impression Technique; Software; Computer-Aided Design
PubMed: 36115710
DOI: 10.1016/j.prosdent.2022.07.014 -
International Journal of Computerized... Oct 2023The adjustment and transfer of a stable occlusion can be a major challenge in prosthetic rehabilitations. The aim of this study was to assess a non-invasive treatment...
AIM
The adjustment and transfer of a stable occlusion can be a major challenge in prosthetic rehabilitations. The aim of this study was to assess a non-invasive treatment option for complex prosthetic rehabilitations and occlusal analyses using 3D-printed restorations clinically.
MATERIALS AND METHODS
Eleven patients received a partial or complete rehabilitation with the aid of 3D-printed restorations (n=171). After 12 months of clinical service, all restorations were analyzed using the United States Public Health Service (USPHS) criteria.
RESULTS
The 12-month clinical data revealed that 3D-printed restorations showed a survival rate of 84.4%. Complications occurred mostly regarding the anatomical form (7%) or marginal integrity (6AC%) and were consequently rated "Charlie" or "Delta." Color stability and color match of 3D-printed restorations were rated "Alpha" in 83% and 73%, respectively, of all restorations. Marginal inflammation was rated "Alpha" in 89% of all restorations. An excellent surface texture and no secondary caries or postoperative sensitivities (100%) were observed.
CONCLUSIONS
3D-printed restorations might be an alternative treatment option for initiating complex prosthetic rehabilitations. Technical complications rarely occurred. Biological complications did not occur at all. The color stability showed promising results after 12 months of clinical service. However, the results should be interpreted with caution. Long-term results with a high number of restorations should be awaited.
PubMed: 37823541
DOI: 10.3290/j.ijcd.b4451424 -
The Journal of Prosthetic Dentistry Jan 2024Duplicating mandibular movement with a semi-adjustable articulator has been reported to lack accuracy. However, although previous studies have analyzed articulator...
STATEMENT OF PROBLEM
Duplicating mandibular movement with a semi-adjustable articulator has been reported to lack accuracy. However, although previous studies have analyzed articulator movement, few have compared excursive tooth contact on the articulator with tooth contact during actual mandibular movement.
PURPOSE
The purpose of this clinical study was to evaluate the concordance of semi-adjustable articulator contacts with intraoral contacts during eccentric movements by using a T-scan occlusal analysis system.
MATERIAL AND METHODS
Forty-two participants with normal occlusion and without signs of temporomandibular disorder were analyzed for the reproducibility of eccentric tooth contact on a semi-adjustable articulator. Maxillary casts made from irreversible hydrocolloid impressions were mounted on a semi-adjustable articulator with the facebow. The condylar inclination of the articulator was set by using interocclusal records. Three recordings of right and left excursive mandibular movement and protrusive mandibular movement were made in the supine position by using the T-scan v9.1. The same procedure was then performed with the articulator. The results of complete mandibular movement from T-scan measurements were divided into 4 time points for analysis: T0, T1, T2, and T3. The concordance of intraoral and articulator occlusal contacts was evaluated at each point, and the occlusal force for each tooth was compared. Overall concordance and concordance of the working and nonworking sides were also calculated. Repeated measures analysis of variance was used to analyze differences between the concordance of intraoral and articulator contacts according to mandibular movement direction, time, and working and nonworking sides (α=.01).
RESULTS
For all teeth, concordance between the intraoral and articulator occlusal contacts during excursive mandibular movement was greatest at T0, decreasing at T1 and T2, and increasing at T3. No significant differences were found in the concordance among the right lateral, left lateral, and protrusive excursion (P>.01). The concordance of working side occlusal contacts during lateral excursion was significantly lower at T3 than that at T0 (P<.01).
CONCLUSIONS
When comparing intraoral and articulator contacts during lateral eccentric mandibular movement, concordance was affected by time and working or nonworking side. Reproducibility of initial eccentric tooth contact on a semi-adjustable articulator appeared to be reliable. However, occlusal adjustment of the working side might be required after prosthesis delivery.
Topics: Humans; Dental Occlusion; Jaw Relation Record; Dental Articulators; Reproducibility of Results; Tooth
PubMed: 35246320
DOI: 10.1016/j.prosdent.2021.11.026 -
The Journal of Prosthetic Dentistry Jan 2024Selecting the optimal polishing procedure to reestablish surface smoothness after occlusal adjustment is essential for the long-term success of glass-ceramic... (Randomized Controlled Trial)
Randomized Controlled Trial
Efficacy of two polishing systems in reestablishing the surface smoothness of posterior monolithic lithium disilicate restorations: One-year results of a split-mouth randomized controlled clinical trial.
STATEMENT OF PROBLEM
Selecting the optimal polishing procedure to reestablish surface smoothness after occlusal adjustment is essential for the long-term success of glass-ceramic restorations. While in vitro studies have shown different effective polishing protocols, clinical trials are lacking.
PURPOSE
The purpose of this split-mouth controlled clinical trial was to evaluate the effectiveness of 2 polishing systems in reestablishing the surface smoothness of posterior monolithic lithium disilicate ceramic restorations.
MATERIAL AND METHODS
Ninety-six restorations that required occlusal adjustment after bonding were randomized into 2 groups: Forty-eight restorations were polished by using the Exa Cerapol polishing kit, and the other 48 restorations were polished by using the Shofu polishing kit. The restorations were replicated with epoxy resin at 3 study times-after bonding (t1), after occlusal adjustment (t2), and after polishing (t3)-for quantitative roughness analysis (R). Representative specimens from each group were qualitatively analyzed by using a confocal laser microscope. Clinical analyses were performed after the polishing procedure and at 30, 180, and 365 days after the polishing procedure by following the United States Public Health Service (USPHS) criteria. ANOVA and the Tukey multiple comparisons parametric tests were computed (α=.05). The Kaplan-Meier test was used to analyze the survival rate of restorations.
RESULTS
No statistically significant difference was found between the Exa Cerapol and Shofu groups (P=.086). A statistically significant difference was found between study times t1 and t2 and between t2 and t3 (both P<.001) in both experimental groups. No statistically significant difference was found between study times t1 and t3 (P=.181) in either experimental group. For the clinical criterion "integrity of restorations," all the elements analyzed indicated an alfa grade at all study times. The survival rate of the restorations was 100%.
CONCLUSIONS
Both polishing kits were effective in reestablishing the surface smoothness of restorations after occlusal adjustment.
Topics: Dental Polishing; Surface Properties; Dental Porcelain; Ceramics; Mouth; Materials Testing
PubMed: 35272843
DOI: 10.1016/j.prosdent.2022.01.008 -
The Journal of Prosthetic Dentistry Dec 2023Worn denture teeth are a common reason for replacing complete dentures. However, clinical studies on the amount of denture tooth wear are lacking.
STATEMENT OF PROBLEM
Worn denture teeth are a common reason for replacing complete dentures. However, clinical studies on the amount of denture tooth wear are lacking.
PURPOSE
The purpose of this clinical study was to compare the clinical wear of denture teeth made from double cross-linked (DCL) versus highly cross-linked (HCL) materials after 1 year in service.
MATERIAL AND METHODS
Fourteen participants received maxillary and mandibular removable complete dentures (RCDs). The participants randomly received either DCL or HCL teeth. Each RCD was scanned with an intraoral scanner 1 week after finishing any occlusal adjustment and after 1 year. Occlusal contact marks were recorded using articulating paper, and photographs were made in centric and eccentric movements. The generated 1-week and 1-year standard tessellation language (STL) files of the scans were obtained and trimmed using the Geomagic X software program. After merging the files, the depth of the wear facets was measured using the software program tool that measures the vertical gap distance in micrometers at 100 points distributed on the contact areas. These areas were identified by using the segment tools in the software program. Repeated measures ANOVA was used to analyze the differences between the collected data (α=.05).
RESULTS
The DCL had higher mean ±standard deviation wear (62.7 ±40 µm) than the HCL (37 ±31 µm) after 1 year in service (P<.001).
CONCLUSIONS
Both DCL and HCL denture teeth showed acceptable clinical wear after 1 year of clinical use. HCL denture teeth showed more resistance to occlusal wear than DCL denture teeth.
PubMed: 38160081
DOI: 10.1016/j.prosdent.2023.11.031 -
Dental Research Journal 2023Horizontal condylar guidance (HCG) is registered by protrusive interocclusal records but in nonarcon articulators, these records can affect the accuracy. The present...
BACKGROUND
Horizontal condylar guidance (HCG) is registered by protrusive interocclusal records but in nonarcon articulators, these records can affect the accuracy. The present study aimed to evaluate the effect of a novel rotation coordinating device (RCD) on condylar guidance setting with protrusive interocclusal records.
MATERIALS AND METHODS
The study was designed as a comparative investigation. Stone maxillary and mandibular casts were mounted on a fully adjustable instrument as the patient. Duplicate casts were mounted on an arcon and a nonarcon articulator with corresponding face bow records and in maximum intercuspation relation. Five different condylar guidance inclinations for both sides (20°, 30°, 40°, 50°, and 60°) were set on the fully adjustable instrument and 16 protrusive interocclusal records were established at each setting. HCG was set for arcon, nonarcon articulators, and nonarcon articulators with RCD. Data were analyzed using one-sample -test to compare with actual HCG and one-way analysis of variance ( =0.05).
RESULTS
Mean HCG for studied articulators was 35.40 for arcon, 30.31 for nonarcon without RCD, and 35.61 for nonarcon with RCD which were significantly different from actual HCG ( < 0.05). HCG of the nonarcon with RCD showed no significant difference with arcon articulator ( = 0.71) while both were significantly different from nonarcon without RCD ( < 0.001).
CONCLUSION
"The RCD" compensates the condylar guidance inclination difference between arcon and nonarcon articulators. The device precisely transfers the hinge movement of the upper member of the articulator to the condylar track.
PubMed: 38020259
DOI: No ID Found -
Heliyon Jan 2024The effect of using the custom disk method (CDM) for fabricating digital dentures on patients' masticatory function should be studied to support its use in clinical...
STATEMENT OF PROBLEM
The effect of using the custom disk method (CDM) for fabricating digital dentures on patients' masticatory function should be studied to support its use in clinical practice.
PURPOSE
To investigate the effect of digital dentures fabricated using CDM on patients' masticatory function.
MATERIAL AND METHODS
This single-center prospective clinical study included 20 patients with edentulous maxillary and mandibular arches who used a complete denture. The digital impression and complete denture manufacturing procedures using CDM have already been reported by Kanazawa et al. (2018) [32] and Soeda et al. (2022) [18] Thedigital dentures fabricated with CDM were delivered to the participants, and periodic adjustments were made until the patient could use the denture without pain. A color-changeable chewing gum, two types of gummy jellies that can evaluate the masticatory function, and pressure-sensitive sheets were used to evaluate the participants' masticatory function at baseline, 1 month, and 6 months following adjustment of the new digital complete dentures fabricated with CDM. These masticatory function values had already been measured in the previous conventional dentures and were recorded as baseline values.
RESULTS
The study participants included 8 women and 12 men (mean age, 77.6 years). The color-changeable chewing gum analysis indicated that there was no significant improvement of masticatory function from baseline to 1 M (P = .083) and 6 M (P = .157).The gummy jelly analysis indicated no significant differences between the masticatory function baseline and 1 month (P = .387); however, a significant improvement was observed from baseline to 6 months (P = .020). Tests with Glucolum indicated a significant improvement from baseline to 1 month (P = .012) and 6 months (P = .003). The maximum bite force and occlusal contact area showed no significant difference at any time point.
CONCLUSIONS
Significant improvement in masticatory function was observed upon evaluation with gummy jelly and Glucolum 6 months after delivering the new digital complete dentures. Under limited conditions, the digital denture fabricated using CDM resulted in good recovery of the masticatory function in elderly edentulous patients. The present results combined with the cost-effectiveness and patient satisfaction associated with CDM indicate its clinical utility.
PubMed: 38192789
DOI: 10.1016/j.heliyon.2023.e23938 -
Clinical Oral Investigations Jan 2024The aim of this study was to compare failure load and initial damage in monolithic, partially veneered, and completely veneered (translucent) zirconia cantilevered fixed...
OBJECTIVES
The aim of this study was to compare failure load and initial damage in monolithic, partially veneered, and completely veneered (translucent) zirconia cantilevered fixed partial dentures (CFPDs), as well as completely veneered metal-ceramic CFPDs under different support and loading configurations.
MATERIALS AND METHODS
Eight test groups with anatomically congruent CFPDs (n = 8/group) were fabricated, differing in CFPD material/support structure/loading direction (load applied via steel ball (Ø 6 mm) 3 mm from the distal end of the pontic for axial loading with a 2-point contact on the inner cusp ridges of the buccal and oral cusps and 1.3 mm below the oral cusp tip for 30° oblique loading): (1) monolithic zirconia/CoCr abutment teeth/axial, (2) monolithic zirconia/CoCr abutment teeth/oblique, (3) partially veneered zirconia/CoCr abutment teeth/axial, (4) partially veneered zirconia/CoCr abutment teeth/oblique, (5) completely veneered zirconia/CoCr abutment teeth/axial, (6) completely veneered CoCr/CoCr abutment teeth/axial (control group), (7) partially veneered zirconia/implants/axial, and (8) partially veneered zirconia/natural teeth/axial. Restorations were artificially aged before failure testing. Statistical analysis was conducted using one-way ANOVA and Tukey post hoc tests.
RESULTS
Mean failure loads ranged from 392 N (group 8) to 1181 N (group 1). Axially loaded monolithic zirconia CFPDs (group 1) and controls (group 6) showed significantly higher failure loads. Oblique loading significantly reduced failure loads for monolithic zirconia CFPDs (group 2). Initial damage was observed in all groups except monolithic zirconia groups, and fractography revealed design flaws (sharp edges at the occlusal boundary of the veneering window) in partially veneered zirconia CFPDs.
CONCLUSIONS
Monolithic zirconia CFPDs might be a viable alternative to completely veneered CoCr CFPDs in terms of fracture load. However, oblique loading of monolithic zirconia CFPDs should be avoided in clinical scenarios. Design improvements are required for partially veneered zirconia CFPDs to enhance their load-bearing capacity.
CLINICAL RELEVANCE
Monolithic zirconia may represent a viable all-ceramic alternative to the established metal-ceramic option for CFPD fabrication. However, in daily clinical practice, careful occlusal adjustment and regular monitoring should ensure that oblique loading of the cantilever is avoided.
Topics: Dental Restoration Failure; Ceramics; Zirconium; Denture, Partial, Fixed; Dental Porcelain; Materials Testing; Dental Stress Analysis; Crowns
PubMed: 38221600
DOI: 10.1007/s00784-024-05501-z -
Orthodontics & Craniofacial Research Jun 2024Investigate associations between cleft laterality in patients with non-syndromic unilateral cleft lip and palate (UCLP) and oral-health, dental-arch, speech,...
OBJECTIVES
Investigate associations between cleft laterality in patients with non-syndromic unilateral cleft lip and palate (UCLP) and oral-health, dental-arch, speech, audiological, psychological and nasolabial-aesthetic outcomes.
METHODS
Secondary data analysis of the outcomes of 5-year-old children with non-syndromic complete UCLP identified from three studies: Cleft Collective (n = 155), Cleft Care UK (CCUK) (n = 266) and Clinical Standards Advisory Group (CSAG) study (n = 238). Outcome measures included occlusal assessment using the 5-year-old's index score, speech intelligibility rating using the CAPS-A Audit tool, audiological assessment using pure tone audiometry, nasolabial aesthetic assessment using the Asher-McDade tool, oral-health assessment using decayed, missing, filled teeth scores and parent-reported outcomes. Logistic regression with adjustment for age, sex and index-of-multiple-deprivation scores were performed.
RESULTS
No differences were found in patient-reported outcomes between the left and right clefts in the Cleft Collective study. From the CCUK study, right clefts had poorer speech (n = 236; 95% CI 1.09, 3.42; and P = .03) and hearing outcomes (n = 211; 95% CI 1.03, 3.43; P = .04). In the CSAG study, patients with left clefts were more likely to be teased (n = 213; 95% CI 0.26, 0.85; and P = .01).
CONCLUSION
Weak associations between cleft laterality, speech, hearing and psychological outcomes were found, however the findings were inconsistent across the studies. This study contributes to evidence of associations between laterality and outcomes in children born with UCLP.
Topics: Humans; Cleft Lip; Cleft Palate; Female; Male; Child, Preschool; Patient Reported Outcome Measures; Speech Intelligibility; Esthetics, Dental; Oral Health
PubMed: 38193240
DOI: 10.1111/ocr.12747 -
Journal of Esthetic and Restorative... Apr 2024This study aimed to present three indicators that represent the proximal contact area gap change under intercuspal occlusion and to see if and how these indicators...
Quantitative evaluation of the proximal contact area gap change characterization under intercuspal occlusion by intraoral 3D scanning: Food impaction with tight proximal contact.
OBJECTIVE
This study aimed to present three indicators that represent the proximal contact area gap change under intercuspal occlusion and to see if and how these indicators influence food impaction with tight proximal contact.
MATERIALS AND METHODS
Ninety volunteers were recruited for bite force measurement and intraoral scanning. Three-dimensional surface data and buccal bite data were obtained for 60 impacted and 60 non-impacted teeth. The scanning data were imported into the Geomagic Studio 2013 to measure three indicators, which included the gap change maximum (Δd, μm), the buccolingual position of Δd (P), and the gap expanded buccolingual range (S, mm). The difference between two groups of three indicators and their relationship with food impaction with tight proximal contact were analyzed by the t test, the Pearson chi-squared test, the nonparametric Mann-Whitney U test, and the binary logistic regression analysis (a = 0.05).
RESULTS
All indicators (Δd, P, and S) were statistically different (p < 0.001, p = 0.002, and p < 0.001) in the impacted and non-impacted groups. Food impaction with tight proximal contact was affected by Δd and S (p < 0.001, p = 0.039), but not by P (p = 0.409).
CONCLUSION
The excessive increase of the gap change maximum and the gap expanded buccolingual range under bite force promoted the occurrence of food impaction with tight proximal contact.
CLINICAL SIGNIFICANCE
The use of intraoral scanning to measure the characteristics of the proximal contact area gap change under bite force may help to deepen our understanding of the pathogenesis of food impaction with tight proximal contact. Importantly it can provide a reference basis for individualizing and quantifying occlusal adjustment treatment.
PubMed: 38634200
DOI: 10.1111/jerd.13240