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The Journal of Prosthetic Dentistry Jul 2022The impact of discrepancies between casts produced from digital scans and conventional impressions on the clinical performance of definitive restorations has not been... (Clinical Trial)
Clinical Trial
STATEMENT OF PROBLEM
The impact of discrepancies between casts produced from digital scans and conventional impressions on the clinical performance of definitive restorations has not been fully investigated.
PURPOSE
The purpose of this crossover clinical trial was to evaluate the clinical performance of single implant-supported restorations fabricated with the digital scanning technique and computer-aided design and computer-aided manufacturing (CAD-CAM) casts compared with the conventional impression technique and gypsum casts in terms of efficiency, accuracy, and participant preference.
MATERIAL AND METHODS
Thirty participants underwent conventional impressions and digital scans of a single implant-supported restoration. Two crowns were fabricated for the same implant with each technique. The time taken for each procedure was recorded. After the accuracy and efficiency analysis of both crowns, the better crown was delivered. A questionnaire was used to assess participant preference and comfort with the techniques. The Wilcoxon signed-rank test was used to compare the time measurements, and multiple comparisons were performed using the Bonferroni method. The chi-square test was used to compare the implant locations of delivered crowns (α=.05).
RESULTS
The total time for the conventional impression technique was 14.16 minutes, while that for the digital scanning technique was significantly less at 11.28 minutes (P<.001). Remake times were 0.56 minutes for conventional impressions and 2.27 for digital scans, also significantly different (P<.001). The adjustment time taken in delivering the crowns was 4.35 minutes for conventional impressions and 3.78 minutes for conventional impressions, which was not statistically significant (P=.940). Of the crowns chosen for delivery, 46.7% were from conventional impressions and 53.3% from digital scans. Participants preferred the digital scanning technique (89%) to the conventional impression technique (11%).
CONCLUSIONS
The digital scanning technique was more efficient than the conventional impression technique for single implant-supported restorations. Digital scans and CAD-CAM implant casts had accuracy comparable with that of conventional impressions and gypsum casts. Most participants preferred digital scans to conventional impressions.
Topics: Calcium Sulfate; Computer-Aided Design; Cross-Over Studies; Crowns; Dental Implants; Dental Impression Materials; Dental Impression Technique; Dental Prosthesis Design; Humans
PubMed: 33602542
DOI: 10.1016/j.prosdent.2020.12.043 -
The Journal of Prosthetic Dentistry Oct 2014Microwave irradiation and immersion in solutions have been recommended for denture disinfection. However, the effect of dry conditions and impression materials has not... (Comparative Study)
Comparative Study
STATEMENT OF PROBLEM
Microwave irradiation and immersion in solutions have been recommended for denture disinfection. However, the effect of dry conditions and impression materials has not been completely evaluated.
PURPOSE
The purpose of this study was to evaluate the effectiveness of microwave irradiation and hydrogen peroxide for the disinfection of dental impression materials.
MATERIAL AND METHODS
Specimens (diameter 10 mm, thickness 2 mm) were made with polyvinyl siloxane. Experimental groups were treated with hydrogen peroxide (group H), microwave irradiation (group M), and a combination of both hydrogen peroxide and microwave irradiation (group MH) for 1 minute, 2 minutes, and 3 minutes. The control group was untreated. The total sample size was 120. The specimens were divided into 2 groups, those exposed to Streptococcus mutans and those exposed to Escherichia coli. The disinfection effect and physical properties (contact angle, compatibility with gypsum, strain in compression, tear strength) were evaluated.
RESULTS
All 3 groups (H, M, MH) were effective in reducing the number of colony forming units (CFU) per unit volume (mL) for both S mutans and E coli compared with the control. The most significant reduction in the CFU/mL of both bacteria was noted in the MH group and was used to compare either treatment alone (P<.05). No statistically significant difference was noted between the control and treatment groups in terms of all of the physical properties tested (P>.05).
CONCLUSIONS
Microwave irradiation was identified as a useful disinfection method against S mutans and E coli, especially when combined with H2O2, without adversely affecting the physical properties of dental impression materials.
Topics: Bacterial Load; Bacteriological Techniques; Calcium Sulfate; Dental Disinfectants; Dental Impression Materials; Dental Stress Analysis; Disinfection; Escherichia coli; Humans; Hydrogen Peroxide; Materials Testing; Microwaves; Polyvinyls; Radiation Dosage; Siloxanes; Streptococcus mutans; Stress, Mechanical; Surface Properties; Temperature; Tensile Strength; Time Factors; Wettability
PubMed: 24819529
DOI: 10.1016/j.prosdent.2013.12.017 -
The International Journal of... 2016The aim of this study was to assess the antimicrobial activity of chemical disinfectants on alginate and silicone impression materials. The effect of chemical... (Comparative Study)
Comparative Study
PURPOSE
The aim of this study was to assess the antimicrobial activity of chemical disinfectants on alginate and silicone impression materials. The effect of chemical disinfectants on the dimensional stability of the impression materials was also assessed.
MATERIALS AND METHODS
For the microbiologic assessment, impressions of the maxillary arch were taken from 14 participants, 7 using alginate and 7 using an addition silicone. The impressions were divided into three sections. Each section was subjected to spraying with MD 520 or Minuten or no disinfection (control), respectively. Antimicrobial action of the chemical disinfectants was assessed by measuring microbial counts in trypticase soy agar (TSA) media and expressing the results in colony-forming units/cm2. The surface area of the dental impressions was calculated by scanning a stone cast using computer-aided design/computer-assisted manufacture and analyzing the data using a custom computer program. The dimensional stability of the impression materials after immersion in disinfectants was assessed by measuring the linear displacement of horizontally restrained materials using a traveling microscope. The percent change in length over 3 hours was thus determined.
RESULTS
Alginate exhibited a higher microbial count than silicone. MD 520 eliminated all microbes as opposed to Minuten. The bacterial growth after Minuten disinfection was almost twice as much for alginate than for addition silicone impressions. The chemical disinfectants affected the alginate dimensional stability. Minuten reduced the shrinkage sustained by alginate during the first hour of storage.
CONCLUSIONS
Alginate harbors three times more microorganisms than silicone impression material. Chemical disinfection by glutaraldehyde-based disinfectant was effective in eliminating all microbial forms for both alginate and silicone without modifying the dimensional stability. Alcohol-based disinfectants, however, reduced the alginate shrinkage during the first 90 minutes of setting. The current studies also propose another method to report the surface area based on accurate estimation by 3D image analysis.
Topics: Adult; Alginates; Anti-Infective Agents; Bacteria; Bacterial Load; Computer-Aided Design; Dental Disinfectants; Dental Impression Materials; Dental Impression Technique; Ethanol; Glutaral; Humans; Imaging, Three-Dimensional; Materials Testing; Maxilla; Polyvinyls; Siloxanes; Surface Properties; Time Factors; Young Adult
PubMed: 26757331
DOI: 10.11607/ijp.4358 -
American Journal of Orthodontics and... May 2019The purpose of this study was to assess the precision of 3D-printed splints generated from different dental model offsets.
INTRODUCTION
The purpose of this study was to assess the precision of 3D-printed splints generated from different dental model offsets.
METHODS
Ten maxillary models were offset by given distances (0.05 mm, 0.1 mm, and 0.2 mm). Digital splints were created by means of the boolean operation. The physical splints were fabricated by means of digital light-processing (DLP) rapid prototyping technologies. A layer of impression material, which could be weighed by means of an electronic analytical balance, was placed in the airspace between the splint and the teeth. We also calculated the shell-to-shell deviations by measuring the 3-dimensional (3D) euclidean distances between the surface points of the scanned splints and the original digital splint and evaluating the results with color-mapping methods.
RESULTS
There was a statistically significant difference in the amounts of impression material remaining in the airspace between the 0.0-mm group and the 0.05-mm, 0.1-mm, and 0.2-mm groups (P < 0.05), between the 0.05-mm and the 0.1-mm and 0.2-mm groups (P < 0.05), and between the 0.0-mm group and the 0.05-mm, 0.1-mm, and 0.2-mm groups (P < 0.05). There was a statistically significant difference in shell-to-shell deviations between the 0.05-mm and the 0.1-mm and 0.2-mm groups (P < 0.05).
CONCLUSIONS
3D-printed splints generated from offset dental models (offset 0.05 mm, 0.1 mm, and 0.2 mm) can fit better on the teeth than splints from no-offset dental models. An offset of 0.1 mm is the best choice of parameter for generating the splint.
Topics: Dental Impression Materials; Humans; Maxilla; Models, Dental; Occlusal Splints; Printing, Three-Dimensional
PubMed: 31053289
DOI: 10.1016/j.ajodo.2018.09.012 -
The Journal of Prosthetic Dentistry Jul 2023Available studies comparing fit accuracy of zirconia fixed partial dentures (FPDs) fabricated from conventional impressions and digital scans provide contradictory... (Meta-Analysis)
Meta-Analysis Review
STATEMENT OF PROBLEM
Available studies comparing fit accuracy of zirconia fixed partial dentures (FPDs) fabricated from conventional impressions and digital scans provide contradictory results. In addition, studies have been heterogeneous and of a limited number to provide conclusive evidence.
PURPOSE
The purpose of this systematic review and meta-analysis was to compare the marginal and intaglio fit of tooth-supported zirconia FPDs fabricated from conventional impressions and digital scans and to investigate the effect of different variables on the fit results.
MATERIAL AND METHODS
An electronic search was performed on the National Library of Medicine (NLM), Cochrane Central Register of Controlled Trials, and Scopus databases. In addition, a manual search was carried out. Studies comparing the fit of tooth-supported zirconia FPDs fabricated from conventional impressions and digital scans and reporting sufficient data for qualitative and quantitative analysis were included. Standard mean differences (SMDs) and 95% confidence intervals (CI) were calculated for meta-analysis. Subgroup analysis was performed to study the effect of variables including restoration form (monolithic or framework), units number, intraoral scanner (IOS) type, conventional impression material, spacer thickness, and abutments region.
RESULTS
The initial search resulted in a total of 608 articles. Nine articles were included in the analysis (1 clinical and 8 in vitro) evaluating 118 restorations. Digital scan displayed significantly better marginal fit (P<.001; SMD: -0.68; 95% CI: -0.92, -0.09) and intaglio fit (P=.020; SMD: -0.51; 95% CI: -0.94, -0.42). Test for subgroup difference showed a significant influence of only impression material type (P=.008) and units number (P=.030) on marginal fit. Digital scan showed significantly better marginal accuracy for 3-unit FPDs than 4-unit FPDs (P<.001; SMD: -1.02; 95% CI: -1.41, -0.63). In addition, digital scanning had significantly better marginal fit with polyvinyl siloxane than polyether (P<.001; SMD: -0.98; 95% CI: -1.32, -0.64). A cement spacer ≤50 μm improved both marginal and intaglio fit in the digital group. The TRIOS scanner resulted in the best performance in the digital group for marginal fit.
CONCLUSIONS
Digital scanning provides significantly better marginal and intaglio fit than conventional impression making for fabricating zirconia FPDs up to 4 units, either in monolithic form or frameworks and at any region of the arch. However, further clinical studies are recommended to obtain more substantial results.
Topics: Computer-Aided Design; Dental Marginal Adaptation; Dental Impression Technique; Zirconium; Denture, Partial, Fixed; Dental Impression Materials; Dental Prosthesis Design
PubMed: 34696907
DOI: 10.1016/j.prosdent.2021.08.025 -
The Journal of Prosthetic Dentistry Mar 2017Studies that evaluated the effect of dental technician disparities on the accuracy of presectioned and postsectioned definitive casts are lacking.
STATEMENT OF PROBLEM
Studies that evaluated the effect of dental technician disparities on the accuracy of presectioned and postsectioned definitive casts are lacking.
PURPOSE
The purpose of this in vitro study was to evaluate the accuracy of presectioned and postsectioned definitive casts fabricated by different dental technicians by using a 3-dimensional computer-aided measurement method.
MATERIAL AND METHODS
An arch-shaped metal master model consisting of 5 abutments resembling prepared mandibular incisors, canines, and first molars and with a 6-degree total angle of convergence was designed and fabricated by computer-aided design and computer-aided manufacturing (CAD-CAM) technology. Complete arch impressions were made (N=110) from the master model, using polyvinyl siloxane (PVS) and delivered to 11 dental technicians. Each technician fabricated 10 definitive casts with dental stone, and the obtained casts were numbered. All casts were sectioned, and removable dies were obtained. The master model and the presectioned and postsectioned definitive casts were digitized with an extraoral scanner, and the virtual master model and virtual presectioned and postsectioned definitive casts were obtained. All definitive casts were compared with the master model by using computer-aided measurements, and the 3-dimensional accuracy of the definitive casts was determined with best fit alignment and represented in color-coded maps. Differences were analyzed using univariate analyses of variance, and the Tukey honest significant differences post hoc tests were used for multiple comparisons (α=.05).
RESULTS
The accuracy of presectioned and postsectioned definitive casts was significantly affected by dental technician disparities (P<.001). The largest dimensional changes were detected in the anterior abutments of both of the definitive casts. The changes mostly occurred in the mesiodistal dimension (P<.001).
CONCLUSIONS
Within the limitations of this in vitro study, the accuracy of presectioned and postsectioned definitive casts is susceptible to dental technician differences.
Topics: Analysis of Variance; Computer-Aided Design; Dental Abutments; Dental Casting Technique; Dental Impression Materials; Dental Impression Technique; Dental Marginal Adaptation; Dental Prosthesis Design; Dental Technicians; Humans; Imaging, Three-Dimensional; Mandible; Models, Dental; Polyvinyls; Siloxanes
PubMed: 27677213
DOI: 10.1016/j.prosdent.2016.06.008 -
Journal of Oral Science Oct 2022This study investigates the attenuation of radiation doses by four materials, heat-polymerized, and self-polymerized polymethyl methacrylate (PMMA), putty-type, and...
PURPOSE
This study investigates the attenuation of radiation doses by four materials, heat-polymerized, and self-polymerized polymethyl methacrylate (PMMA), putty-type, and injection-type polyvinyl siloxane (PVS) impression material. This in vitro study should aid in the selection of dental materials for radiotherapy prostheses, thereby minimizing the possibility of radiotherapy side effects.
METHODS
Specimens of each type were fabricated as a 5 × 5 cm squares with a thickness of 10 mm. Heat-polymerizing PMMA, self-polymerizing PMMA, putty-type PVS impression material, and injection-type PVS impression material were selected. A calibration curve was created to determine the association of radiation doses and grayscale value. A linear accelerator was used to irradiate the specimens. The radiation doses above and below the materials were measured using radiochromic film dosimetry. After film irradiation, the pixel scale of color change was used to determine the radiation dose based on the created calibration curve. The results were exported to find average doses to calculate the percentage of the attenuated dose for a comparison of the four materials.
RESULTS
The average attenuated doses of heat-polymerizing PMMA, self-polymerizing PMMA, putty-type PVS, and injection-type PVS were 10.8%, 6.2%, 17.2%, and 14.2% respectively.
CONCLUSION
PVS showed higher attenuating radiation exposure compared with PMMA.
Topics: Dental Implants; Dental Impression Materials; Polymethyl Methacrylate; Polyvinyls; Siloxanes
PubMed: 36070925
DOI: 10.2334/josnusd.22-0167 -
Odontology Jan 2021Oral scanners allow dental impressions to be taken in a short time without the use of an impression material. However, it has been noted that high impression accuracy...
Oral scanners allow dental impressions to be taken in a short time without the use of an impression material. However, it has been noted that high impression accuracy cannot be obtained in cases where the abutment is inclined or in cases where the span is long. Consequently, in daily clinical practice, impressions are often created using silicone impression material. When taking an impression using silicone impression material, the curing time or the removal time of the impression material are often based on the intuition of the dental staff. This study investigated the effects of impression holding time and impression tray removal speed on the dimensional accuracy of impressions. A specimen with an abutment inclined 30° to the removal direction of an impression was prepared. Four types of silicone rubber impression materials were used. Impressions were taken with two levels of holding time and two levels of removal speed using an autograph. The diameter of stone models was measured at 3, 6, and 9 mm from the baseline of each. The height of the inclined and opposite sides was also measured. Two-way analysis of variance was used to analyze data regarding the assessment of the effects of holding time and tray removal speed. The reproducibility of the impressions was affected by the volume of undercut caused by the inclined abutment. For a large undercut, longer holding times and faster tray removal speeds are recommended to reduce the deformation of silicone rubber impressions.
Topics: Dental Impression Materials; Dental Impression Technique; Humans; Models, Dental; Reproducibility of Results; Silicones
PubMed: 32691180
DOI: 10.1007/s10266-020-00537-5 -
The Journal of Prosthetic Dentistry May 2020The definitive impression for a single-unit crown involves many material and technique factors that may affect the success of the crown.
Clinical acceptance of single-unit crowns and its association with impression and tissue displacement techniques: Findings from the National Dental Practice-Based Research Network.
STATEMENT OF PROBLEM
The definitive impression for a single-unit crown involves many material and technique factors that may affect the success of the crown.
PURPOSE
The purpose of this prospective cohort study was to determine whether impression technique (tray selection), impression material, or tissue displacement technique are associated with the clinical acceptability of the crown (CAC).
MATERIAL AND METHODS
Dentists in the National Dental Practice-Based Research Network documented details of the preparation, impression, and delivery of 3730 consecutive single-unit crowns. Mixed-effects logistic regression analyses were performed to evaluate associations between impression techniques and materials and the CAC and to assess associations between the presence of a subgingival margin with the displacement technique and the outcome variables CAC and number of impressions required.
RESULTS
Of the 3730 crowns, 3589 (96.2%) were deemed clinically acceptable. A significant difference in the CAC was found with different impression techniques (P<.001) and different impression materials (P<.001). The percentage of the CAC for digital scans was 99.5%, 95.8% for dual-arch trays, 95.2% for quadrant trays, and 94.0% for complete-arch impression trays. Although no statistically significant difference was found in the CAC produced with dual-arch trays without both mesial and distal contacts, crowns fabricated under these conditions were less likely to achieve excellent occlusion. The percentage of the CAC for digital scans was 99.5%, 97.0% for polyether impressions, 95.5% for polyvinyl siloxane impressions, and 90.5% for other impression materials. Accounting for the location of the margin, the use of a dual-cord displacement technique was significantly associated with lower rates of requiring more than 1 impression (P=.015, odds ratio=1.43).
CONCLUSIONS
Dual-arch trays produced clinically acceptable crowns; however, if the prepared tooth was unbounded, the occlusal fit was more likely to have been compromised. Digital scans produced a slightly higher rate of CAC than conventional impression materials. The use of a dual-cord technique was associated with a decreased need to remake impressions when the margins were subgingival.
Topics: Crowns; Dental Impression Materials; Dental Impression Technique; Models, Dental; Prospective Studies; Tooth
PubMed: 31590974
DOI: 10.1016/j.prosdent.2019.05.016 -
Primary Dental Journal Mar 2023Fibrous ridges on the edentulous maxillary arch are commonly found in combination syndrome or due to ill-fitting dentures. Often, these cases are managed conservatively...
Fibrous ridges on the edentulous maxillary arch are commonly found in combination syndrome or due to ill-fitting dentures. Often, these cases are managed conservatively using modified impression techniques to achieve better support and peripheral seal without displacing the movable tissue. Many impression techniques were proposed and justified with their respective ideologies, but some may complicate both the clinical and laboratory procedures. In this report, two simplified techniques are demonstrated to make an impression of the maxillary arch with fibrous ridges. Laboratory steps in custom tray fabrication are also emphasised for a successful and predictable impression.
Topics: Humans; Denture Design; Dental Impression Materials; Dental Impression Technique; Mouth, Edentulous; Maxilla; Jaw, Edentulous
PubMed: 36916614
DOI: 10.1177/20501684231153909