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The European Journal of Prosthodontics... Nov 2020The aim of this study was to compare the clinical accuracy of digital and conventional dental implant impressions. Two types of implant impressions were made for each...
The aim of this study was to compare the clinical accuracy of digital and conventional dental implant impressions. Two types of implant impressions were made for each case, namely a conventional open-tray impression and a digital implant impression (DII) using a Trios IOS. Master casts were scanned using a D800 laboratory scanner and STL files were retrieved from conventional and digital workflows to be exported for comparison. The distance between center points, angulation, rotation, vertical shift, and surface mismatch of the scan bodies were evaluated and compared between conventional and digital impression techniques. Comparing digital and conventional impression techniques the following factors showed statistically significant differences: distance (73.7±75 μm), angulation (0.42±0.3°), and surface mismatch of scan bodies. The difference in conventional and digital impression techniques as regards to angulation and distance between the implants were associated with distance, angle, and vertical shift differences in scan. The mismatch of the scanned surface of scan bodies was twice higher for the intraoral scanner group. Clinicians should therefore control the implant suprastructures clinically and also using casts (e.g. printed casts) when a digital scan is planned.
Topics: Computer-Aided Design; Dental Implants; Dental Impression Materials; Dental Impression Technique; Models, Dental
PubMed: 32673469
DOI: 10.1922/EJPRD_02028Rutkunas09 -
The Journal of Prosthetic Dentistry Oct 2015Some elastomeric impression materials are hydrophobic, and it is often necessary to take definitive impressions of teeth coated with some saliva. New hydrophilic...
STATEMENT OF PROBLEM
Some elastomeric impression materials are hydrophobic, and it is often necessary to take definitive impressions of teeth coated with some saliva. New hydrophilic materials have been developed.
PURPOSE
The purpose of this in vitro study was to compare contact angles of water and saliva on 7 unset elastomeric impression materials at 5 time points from the start of mixing.
MATERIAL AND METHODS
Two traditional polyvinyl siloxane (PVS) (Aquasil, Take 1), 2 modified PVS (Imprint 4, Panasil), a polyether (Impregum), and 2 hybrid (Identium, EXA'lence) materials were compared. Each material was flattened to 2 mm and a 5 μL drop of distilled water or saliva was dropped on the surface at 25 seconds (t0) after the start of mix. Contact angle measurements were made with a digital microscope at initial contact (t0), t1=2 seconds, t2=5 seconds, t3=50% working time, and t4=95% working time. Data were analyzed with a generalized linear mixed model analysis, and individual 1-way ANOVA and Tukey HSD post hoc tests (α=.05).
RESULTS
For water, materials grouped into 3 categories at all time-points: the modified PVS and one hybrid material (Identium) produced the lowest contact angles, the polyether material was intermediate, and the traditional PVS materials and the other hybrid (EXA'lence) produced the highest contact angles. For saliva, Identium, Impregum, and Imprint 4 were in the group with the lowest contact angle at most time points.
CONCLUSION
Modified PVS materials and one of the hybrid materials are more hydrophilic than traditional PVS materials when measured with water. Saliva behaves differently than water in contact angle measurement on unset impression material and produces a lower contact angle on polyether based materials.
Topics: Dental Impression Materials; Dental Impression Technique; Elastomers; Humans; Hydrophobic and Hydrophilic Interactions; Materials Testing; Resins, Synthetic; Saliva; Surface Properties; Water; Wettability
PubMed: 26187106
DOI: 10.1016/j.prosdent.2015.05.004 -
The European Journal of Prosthodontics... Feb 2020Reports concerning the accuracy of intraoral digital impression systems are limited. This study aimed to assess the effects of scan body types and shapes on digital...
OBJECTIVES
Reports concerning the accuracy of intraoral digital impression systems are limited. This study aimed to assess the effects of scan body types and shapes on digital impression accuracy and scanning time in all-on-four restorations.
METHODS
This in vitro study was conducted with two acrylic maxillary models. Two implant systems with different connection types (internal trilobe and external hexagon connection) were inserted according to the all-on-four design. Scanning was performed using Doowon, NT-Trading, and DESS scan bodies. Changes in implants' positions (ΔR) and angulation (ΔA), and the implants' distance from the reference pin (ΔD) compared with the actual model were determined. Scanning times were also measured and compared.
RESULTS
The effects of implant connections and scan bodies on ΔR and ΔA were significant (p ⟨0.05). Implant angulation could also affect ΔA (p=0.019). ΔD was only affected by scan body (p ⟨0.001). The three scan bodies were significantly different in terms of scanning time (p=0.001).
CONCLUSION
The results showed that scan body type and shape, and implant connection and angulation could affect digital impression accuracy in all-on-four restorations. For both internal and external connections, the NT-Trading and DESS scan bodies had the shortest and longest scanning times, respectively.
Topics: Computer-Aided Design; Dental Implants; Dental Impression Materials; Dental Impression Technique; Dental Prosthesis, Implant-Supported; Models, Dental
PubMed: 32036633
DOI: 10.1922/EJPRD_1962Moslemion10 -
The Journal of Prosthetic Dentistry Dec 2020Displacement of impression copings and/or implant replicas during impression making and dimensional changes that occur during clinical and laboratory phases of making...
STATEMENT OF PROBLEM
Displacement of impression copings and/or implant replicas during impression making and dimensional changes that occur during clinical and laboratory phases of making multiunit implant prostheses may affect the accuracy and fit of the prostheses.
PURPOSE
The purpose of this qualitative study was to investigate and compare 3 different impression techniques for osseointegrated dental implant transfer procedures.
MATERIAL AND METHODS
Three impression transfer approaches were evaluated and compared: closed-tray impression technique (CTT), impression with plastic snap-fit impression copings; open-tray impression technique (OTT), impression with independent square copings; and OTT joining the impression copings with a photo-polymerized resin (PPT). A reference acrylic resin model with 4 implants was fabricated. Polyvinyl siloxane with a stock tray was used to make 45 impressions (n=15 for each impression technique), and 45 die definitive stone casts. A computer-aided design and computer-aided manufacturing (CAD-CAM) titanium framework was fabricated on the reference model. Three blinded operators evaluated the fit of the CAD-CAM titanium framework on each model to find clinically acceptable fit. The Kappa test was used for the agreement between the examiners (α=.05).
RESULTS
Agreement was found among the 3 examiners on 44 of 45 specimens (Kappa value= 0.939; P<.001). In the CTT group, 14 casts were found to be acceptable. In the OTT group, nearly half of the specimens produced unacceptable fitting casts, whereas in the PPT group, 13 casts were found acceptable.
CONCLUSIONS
CTT and PPT produced more accurate casts than the OTT technique, which yielded inferior results.
Topics: Acrylic Resins; Computer-Aided Design; Dental Implants; Dental Impression Materials; Dental Impression Technique; Models, Dental
PubMed: 32709404
DOI: 10.1016/j.prosdent.2020.04.025 -
The Journal of Prosthetic Dentistry Apr 2017Polyvinyl siloxane impression material has been widely used as a lingual matrix for rebuilding missing tooth structure with composite resin. The composite resin is light...
STATEMENT OF PROBLEM
Polyvinyl siloxane impression material has been widely used as a lingual matrix for rebuilding missing tooth structure with composite resin. The composite resin is light polymerized in contact with the polyvinyl siloxane impression material. However, polyvinyl siloxane impression material has been shown to interact with other dental materials.
PURPOSE
The purpose of this study was to assess the effect of polyvinyl siloxane impression materials on the polymerization of composite resins by assessing the Vickers microhardness and degree of conversion of polyvinyl siloxane.
MATERIAL AND METHODS
The composite resins were light polymerized in contact with 3 polyvinyl siloxane impression materials (Flexitime Easy Putty; President Light Body; Xantopren L Blue) (n=8) and in contact with a matrix strip as the control group (n=8). Vickers microhardness and degree of conversion on contact surfaces were measured to evaluate the polymerization of composite resins. The depth of the effect was assessed by Vickers microhardness on section surfaces and observed with scanning electron microscopy. The results were analyzed by 1-way analysis of variance and the post hoc Tukey honest significant differences test (α=.05).
RESULTS
The Vickers microhardness and degree of conversion values on the contact surfaces of the experiment groups were significantly lower than those of the control group (P<.05); the Vickers microhardness values on the section surfaces indicated that there was no significant difference at the same depth of different groups (P>.05). The scanning electron microscope observation showed that an approximately 10-μm deep unpolymerized layer was found in the experimental group.
CONCLUSIONS
Polyvinyl siloxane impression materials have an inhibitory effect on the polymerization of the composite resins, but just limited to within approximately 10 μm from the surface in contact with the impression material.
Topics: Composite Resins; Dental Impression Materials; Hardness; Microscopy, Electron, Scanning; Polymerization; Polyvinyls; Siloxanes
PubMed: 27765393
DOI: 10.1016/j.prosdent.2016.06.023 -
BMC Oral Health Nov 2020Fixed prosthodontics require an accurate impression for the teeth and the area to be restored for the laboratory to fabricate the desired restoration without mistakes....
BACKGROUND
Fixed prosthodontics require an accurate impression for the teeth and the area to be restored for the laboratory to fabricate the desired restoration without mistakes. This study evaluated the quality of impressions received by private laboratories for the fabrication of fixed prosthesis by describing the frequency of clinically detectable errors and by analyzing association between the various factors involved.
METHODS
165 impressions were collected from four dental laboratories. Jaw involved, type of tray, size of tray, number of prepared units, type of impression materials, techniques and viscosity in case of elastomeric impressions and type of prosthesis requested were recorded. Data referring to errors and visible defects including errors in finish line, in preparation area, in silicone impression technique and blood in impression were also documented. Factors affecting errors present were also assessed. Association between dentist gender and experience years and impression errors was assessed. Chi square and Fisher exact tests used to examine the association between categorical variables and outcomes.
RESULTS
The total of error considering not immediately pouring as an error. Alginate was the most impression used. of impressions evaluated (50.9%), 97% were have at least one visible error; 92.1% had errors in finish line, 53.9% had errors in preparation area and (72.8%) of elastomeric impressions were have at least one error in technique. Blood in impression was detected in 52.1% of impressions. Significant association was found between material type and errors in finishing line and preparation area. Significant relationships were found between gender and errors in silicone impression technique (p < 0.05).
CONCLUSION
Within the limitations of this study, high frequency of detectable errors was found in fixed prosthesis impressions received by private dental laboratories. This high frequency is of serious concern, as this will result in poor fitted fixed prosthesis provided to patients.
Topics: Dental Implants; Dental Impression Materials; Dental Impression Technique; Humans; Laboratories; Models, Dental; Yemen
PubMed: 33148226
DOI: 10.1186/s12903-020-01294-1 -
The Journal of Prosthetic Dentistry Feb 2022The effects of design parameters of polylactic acid (PLA) custom trays manufactured by fused deposition modeling (FDM) on the accuracy of partially edentulous definitive...
STATEMENT OF PROBLEM
The effects of design parameters of polylactic acid (PLA) custom trays manufactured by fused deposition modeling (FDM) on the accuracy of partially edentulous definitive casts have not been thoroughly explored.
PURPOSE
The purpose of this in vitro study was to explore the effects of the impression gap and base thickness of FDM-printed PLA custom trays on the accuracy of maxillary and mandibular definitive casts with Kennedy class II, modification I partial edentulism and to optimize these 2 design parameters.
MATERIAL AND METHODS
Custom trays with a 1-mm, 2-mm, or 3-mm impression gap and 1-mm, 1.5-mm, or 2-mm base thickness were designed on a pair of maxillary and mandibular resin casts and printed with PLA materials by using an FDM printer. Two-step silicone impressions were made by using these custom trays or stock metal trays on resin casts. Digital scans of definitive casts from these impressions were aligned one by one with those of resin casts. Three-dimensional deviations of the tooth area, mucosal area, and overall area were analyzed by using root mean square (RMS) as a metric. Two-way and 1-way analyses of variance with the RMSs as the dependent variable were carried out (α=.05).
RESULTS
The accuracy of definitive casts from custom trays with a 2.0-mm or 3.0-mm impression gap and 1.5-mm or 2.0-mm base thickness was significantly better than that of definitive casts from custom trays with a 1.0-mm impression gap or 1.0-mm base thickness and was not significantly different from that of definitive casts from stock metal trays.
CONCLUSIONS
Considering the accuracy of definitive casts, the optimal base thickness of FDM-printed PLA custom trays was 1.5 mm or 2.0 mm and the optimal impression gap was 2.0 mm or 3.0 mm for Kennedy class II, modification I partial edentulism.
Topics: Dental Impression Materials; Dental Impression Technique; Models, Dental; Polyesters
PubMed: 34924189
DOI: 10.1016/j.prosdent.2021.10.030 -
The Journal of Prosthetic Dentistry Oct 2016The impression technique described combines elastomeric impression materials and irreversible hydrocolloid to make an accurate preliminary impression of extremely mobile...
The impression technique described combines elastomeric impression materials and irreversible hydrocolloid to make an accurate preliminary impression of extremely mobile and misaligned teeth. Upon setting, the materials are removed from the mouth in 3 different directions and reassembled extraorally. This technique provides an alternative, easy, accurate, and safe way to make a preliminary impression of mobile, periodontally involved teeth.
Topics: Dental Impression Materials; Dental Impression Technique; Humans; Tooth Mobility
PubMed: 27402417
DOI: 10.1016/j.prosdent.2016.04.006 -
The Journal of Prosthetic Dentistry Jan 2020Which impression material, impression tray type, and implant impression technique combination produces the most accurate complete-arch impression is unclear.
STATEMENT OF PROBLEM
Which impression material, impression tray type, and implant impression technique combination produces the most accurate complete-arch impression is unclear.
PURPOSE
The purpose of this in vitro study was to compare the implant impression accuracy of a completely edentulous arch made with addition silicone occlusal registration material and an open tray with the implant impression accuracy of other conventional impression techniques.
MATERIAL AND METHODS
A master cast was fabricated from Type IV gypsum with four 3.8-mm diameter implants with internal hexagon located in the area of mandibular canines and first molars. Impressions (N=60) were made from the master cast using the 6 techniques investigated: group B-OC-N with occlusal registration impression material (B), open custom tray (OC), and nonsplinted impression pins (N); group B-OS-N with occlusal registration impression material (B), open plastic perforated stock tray (OS), and nonsplinted impression pins (N); group PE-OC-N with polyether medium-body impression material (PE), open custom tray (OC), and nonsplinted impression pins (N); group PE-OC-S with polyether medium-body impression material (PE), open custom tray (OC), and impression pins splinted (S) with autopolymerizing resin cut after 17 minutes and reconnected; group PE-CC-N with polyether medium-body impression material (PE), closed custom tray (CC), and nonsplinted impression pins (N); group PVS-CS-N with simultaneous double-mix polyvinyl siloxane impression material (PVS), closed stock perforated metal tray (CS), and nonsplinted impression pins (N). Type IV gypsum casts were fabricated 24 hours after making the impressions. A computerized numerical control 3D coordinate measuring machine was used to measure the absolute differences of the distances between the centroids of the 4 implants among the casts produced and the distances measured at the master cast. The Kruskal-Wallis test was used to determine differences among the experimental groups (α=.05). The Mann-Whitney U post hoc analysis was used for all group combinations.
RESULTS
No significant differences were found between the test groups B-OC-N and PE-OC-S, which were more accurate than the other groups. Group B-OS-N resulted in the least accurate impressions of all experimental groups. Group PE-OC-S resulted in more accurate impressions than the PE-OC-N group. No statistically significant differences were found between groups PE-OC-N and PE-CC-N or between groups PVS-CS-N and PE-CC-N.
CONCLUSIONS
For complete edentulism, the use of silicone occlusal registration material with an open custom tray and nonsplinted impression pins resulted in impressions as accurate as those produced with PE open custom tray with splinted impression pins. These 2 techniques resulted in more accurate impressions than the other 4 techniques studied.
Topics: Calcium Sulfate; Dental Implants; Dental Impression Materials; Dental Impression Technique; Models, Dental
PubMed: 31079882
DOI: 10.1016/j.prosdent.2018.12.011 -
Journal of Dentistry Nov 2022Splinting of impression copings is generally recommended for complex implant-supported restorations. It can also be used in the digital workflow when a control model is...
BACKGROUND
Splinting of impression copings is generally recommended for complex implant-supported restorations. It can also be used in the digital workflow when a control model is needed to improve the fit of the prosthesis. However, there is a lack of knowledge on how dimensional accuracy is affected by different splinting techniques and time factors.
OBJECTIVES
To evaluate the time factor on the dimensional stability of different implant impression splinting techniques used in the conventional and digital workflow.
MATERIALS AND METHODS
Ten pairs of implant analogs were fixed to a stainless steel bar. Modified impression copings were connected to the analogs and eight splinting strategies evaluated (n=10): (1) type I impression plaster (PLA), (2) autopolymerizing acrylic resin, cut and rejoin technique (PTR), (3) light-cured acrylic resin, cut and rejoin technique (ILC), (4) light-cured acrylic resin, no cutting and rejoining (ILN), (5) VPS bite registration material (SBR), (6) bis-acryl bite registration material (LXB), (7) bis-acryl composite resin (PTP), (8) 3D printed splint (3DP). In each group, the position of modified impression copings was scanned with a laboratory scanner at different time points: (1) unsplinted impression copings (baseline), (2) 2 h after splinting, (3) 24 h after splinting. Modified impression coping design allowed using metrology software to measure and compare distance, vertical, angle and rotational deviations between impression copings.
RESULTS
All types of splints showed dimensional deviations. After 2 h of splinting, the lowest distance deviation was recorded in PTR (15.4±6.15µm), vertical deviation - in ILC (19.2±27.37µm), angle deviation - in ILC (0.08±0.1°), rotation - in LXB (0.2±0.24°) groups. Comparing results 2 and 24 h after connection of impression copings, statistically significant deviations in the distance were recorded in groups PLA (-5.6±5.95 µm), PTR (5.5±7.01µm), ILN (19.2±14.26µm), PTP (23.8±12.55µm).
CONCLUSIONS
The best dimensional accuracy was observed in the ILC group, followed by PTR and 3DP groups.
CLINICAL SIGNIFICANCE
Proper selection of splinting technique and polymerization time can increase the accuracy of conventional or digital impressions. Splinting techniques with rigid materials, proper polymerization and compensating for material shrinkage seem to produce the best results.
Topics: Dental Impression Technique; Dental Impression Materials; Dental Implants; Stainless Steel; Acrylic Resins; Composite Resins; Polyesters
PubMed: 36029970
DOI: 10.1016/j.jdent.2022.104267