In Vitro Implant Impression Accuracy Using a New Photopolymerizing SDR Splinting Material

Investigation of the effects of arch size and implant angulation on the accuracy of digital impression using two intraoral scanners: An in vitro study

OBJECTIVES

The aim of this in vitro study was to evaluate the effect of arch size and implant angulation on the accuracy of digital impression in two intraoral scanners of Trios (3shape) and CEREC (Omnicam).

MATERIAL AND METHODS

Four acrylic models each including six implants at sites 11, 12, 15, 17, 23, and 27 were used, including large with parallel implants, large with angled implants, small with parallel implants, and small with angled implants. After tightening the scan bodies, distance measurements were done using a coordinate measuring machine. Then, each model was scanned 10 times using each scanner. Trueness and precision measurements were finally computed.

RESULTS

The trueness values ranged from 20 to 260 μm in CEREC Omnicam, and from 40 to 1030 μm in Trios. The precision values ranged from 30 to 190 μm in CEREC Omnicam, while from 50 to 770 μm in Trios. The multivariate test analysis indicated that the measured distances via two scanners and different models show different behaviors. Pairwise interactions between these three variables were significant (p < .05). Pairwise interactions between these variables were also significant. (p < .0001).

CONCLUSIONS

Arch width could affect the accuracy of digital impression; by rotating toward the second quadrant and end points of the scan, errors have increased. However, the angulation of the implants had no effect on the accuracy of digital impression. The CEREC Omnicam scanner showed higher accuracy (trueness and precision) compared to the Trios (3shape) one.

Clinical performance of lithium disilicate and zirconia CAD/CAM crowns using digital impressions: A systematic review

PURPOSE

The purpose of this systematic review was to compare the clinical performance of lithium disilicate (LDS) and zirconia (Z) single crowns manufactured by computer-aided design/computer-aided manufacturing (CAD/CAM) systems using intraoral optical scanners (IOS).

MATERIALS AND METHODS

An electronic search for articles published between January 2012 and January 2022 in the English language was performed with the Medline/Pubmed database under the guidelines of Preferred Reporting Items for Systemic Reviews and Meta-analysis (PRISMA). The specific search terms used were "zirconia", "lithium disilicate", "CAD/CAM", "intraoral optical scanner", and "survival".

RESULTS

The initial electronic search resulted in 278 articles. Most of the resulting articles were excluded, six clinical studies addressing the clinical outcomes of Z and LDS crowns fitted the inclusion criteria and were selected for review. Of these six studies, three were randomised controlled trials, two were retrospective studies, and one was a prospective study. To quantify the clinical performance of the crowns several parameters were recorded, including fractures, endodontic complications, periodontal complications, technical complications, aesthetic complications, and biological complications. It was noted that the most common technical complication of Z and LDS crowns was chipping at a rate of 1.4% and 5% respectively. Regarding Z crowns, aesthetic concerns were the most frequently observed complication.

CONCLUSION

The outcomes of this systematic review indicate that Z and LDS crowns display a similar incidence of periodontal and endodontic complications when compared to metal-ceramic crowns, suggesting that these all-ceramic materials are viable alternatives. The incidence of chipping was higher in LDS crowns compared to other materials, while Z crowns were inferior in terms of aesthetics.

Comparison of the accuracy of fixture-level implant impressions using two different materials for splinting

Background. Various materials are used for splinting impression copings, the most common of which are auto-polymerizing resins. In this study, a new light-curing pattern resin (Jig-Gel) was investigated and compared with auto-polymerizing resins using two different splinting methods. Methods. After taking impressions with two different materials, a digital caliper with an accuracy of 0.01 mm was used for splinting and measuring the distances between the external parts of the analogs inside the plaster cast. The accuracy was also compared in five groups as follows; group 1: splinting of impression copings by auto-polymerizing acrylic resin, group 2: cutting the splinting of impres-sion copings with self-polymerizing acrylic resin, group 3: splinting of impression copings with a light-cured resin pattern (Jig-Gel), group 4: splinting of impression copings cut by a light-cured resin pattern, and group 5: impression with no splint. All statistical analyses were performed with SPSS 17. Statistical significance was set at P<0.05. Results. The highest impression accuracy was obtained in the group without cutting the splint of the impression copings using auto-polymerizing acrylic resin. Compared with the impression methods, impression making of non-splint samples in an impression coping was the least accurate, and the results for the two used methods were similar. Conclusion. The results of this study showed that the combination of the impression coping method and auto-polymerizing acrylic resin had the highest accuracy.

The effect of different implant impression splinting techniques and time on the dimensional accuracy: An in vitro study

Splinting of impression copings is generally recommended for more complex implant-supported restorations. It can also be used in the digital workflow when the 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 strategies 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 an accurate laboratory scanner at different time points: 1) unsplinted impression copings (baseline), 2) 2 hours after splinting, 3) 24 hours 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 hours 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 hours 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).

CONCLUSION

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 produce the best results.

Investigation of the Accuracy of Four Intraoral Scanners in Mandibular Full-Arch Digital Implant Impression: A Comparative In Vitro Study

Background: We compare the accuracy of new intraoral scanners (IOSs) in full-arch digital implant impressions. Methods: A master model with six scan bodies was milled in poly(methyl methacrylate), measured by using a coordinate measuring machine, and scanned 15 times with four IOSs: PrimeScan, Medit i500, Vatech EZ scan, and iTero. The software was developed to identify the position points on each scan body. The 3D position and distance analysis were performed. Results: The average and ± standard deviation of the 3D position analysis was 29 μm ± 6 μm for PrimeScan, 39 μm ± 6 μm for iTero, 48 μm ± 18 μm for Mediti500, and 118 μm ± 24 μm for Vatech EZ scan (p < 0.05). Conclusions: All IOSs are able to make a digital complete implant impression in vitro according to the average misfit value reported in literature (150 μm); however, the 3D distance analysis showed that only the Primescan and iTero presented negligible systematic error sources.

Influence of ceramic firing on marginal gap accuracy and metal-ceramic bond strength of 3D-printed Co-Cr frameworks

STATEMENT OF PROBLEM

The marginal gap and ceramic bond strength of metal-ceramic restorations are important for success. However, studies evaluating the marginal gap and ceramic bond strength of fixed partial dentures (FPDs) produced with 3D printing technologies such as selective laser melting (SLM) are scarce.

PURPOSE

The purpose of this in vitro study was to investigate the marginal gap of cobalt-chromium (Co-Cr) alloy frameworks produced by SLM technology before and after ceramic firing. Additionally, the metal-ceramic bond strength was evaluated with the Schwickerath crack-initiation test according to the International Standards Organization (ISO) 9693-1:2012.

MATERIAL AND METHODS

Conventional impressions were made, and the definitive cast of a patient requiring a 4-unit FPD was scanned. After designing the FPD, the files were sent to a service center for the fabrication of a metal master model, 80 Co-Cr frameworks, and 80 flat specimens (25×3×0.5 mm) with SLM technology. The marginal gap between frameworks and the abutment tooth of the metal master model was nondestructively measured by using an optical coordinate-measuring machine. A total of 80 sets, consisting of 1 framework and 1 flat specimen, were sent to 80 dental laboratory technicians for ceramic firing. Detailed instructions for correct manipulation of the framework and flat specimen were provided. The marginal gap was remeasured, and the 3-point bend test was used to evaluate metal-ceramic bond strength.

RESULTS

Only 28 of the 80 dental technicians returned the specimens within a prespecified time and/or in adequate condition. The mean ±standard deviation marginal gap of the framework before ceramic firing was 25 ±9 μm and 34 ±12 μm after firing. The difference was statistically significant (P=.001). The mean ±standard deviation 3-point bend strength was 33 ±9 MPa.

CONCLUSIONS

Ceramic firing affected the marginal gap; however, all Co-Cr frameworks had a marginal gap lower than 120 μm, which is reported to be a clinically acceptable limit. Most of the specimens (80%) had a metal-ceramic bond strength value higher than the 25-MPa ISO 9693 requirement. Five of 28 dental laboratory technicians were not able to comply with ceramic firing instructions.

Full arch digital scanning systems performances for implant-supported fixed dental prostheses: a comparative study of 8 intraoral scanners

PURPOSE

Compare the accuracy of intraoral digital impression in full-arch implant-supported fixed dental prosthesis acquired with eight different intraoral scanner (Ios).

METHODS

A polymethyl methacrylate acrylic model of an edentulous mandible with six scan-abutment was used as a master model and its dimensions measured with a coordinate measuring machine. Eight different Ios were used to generate digital impression: True Definition, Trios, Cerec Omnicam, 3D progress, CS3500, CS3600, Planmeca Emelard and Dental Wings. Fifteen digital impressions were made. A software called "Scan-abut" was developed to analyse and compare the digital impression with the master model, obtaining the scanning accuracy. The three-dimensional (3D) position and distance analysis were performed.

RESULTS

Mean value of the 3D position analysis showed that the True Definition (31 μm ± 8 μm) and Trios (32 μm ± 5 μm) have the best performance of the group. The Cerec Omnicam (71 μm ± 55 μm), CS3600 (61 μm ± 14 μm) have an average performance. The CS3500 (107 μm ± 28 μm) and Planmeca Emelard (101 μm ± 38 μm) present a middle-low performance, while the 3D progress (344 μm ± 121 μm) and Dental Wings (148 μm ± 64 μm) show the low performance. The 3D distance analysis showed a good linear relationship between the errors and scan-abutment distance only with the True Definition and CS3600.

CONCLUSIONS

Not all scanners are suitable for digital impression in full-arch implant-supported fixed dental prosthesis and the weight of the output files is independent from the accuracy of the Ios.

In vitro assessment of the accuracy of digital impressions prepared using a single system for full-arch restorations on implants

PURPOSE

This study describes a method for measuring the accuracy of the virtual impression.

METHODS

In vitro measurements according to a metrological approach were based on (1) use of an opto-mechanical coordinate measuring machine to acquire 3D points from a master model, (2) the mathematical reconstruction of regular geometric features (planes, cylinders, points) from 3D points or an STL file, and (3) consistent definition and evaluation of position and distance errors describing scanning inaccuracies. Two expert and two inexpert operators each made five impressions. The 3D position error, with its relevant X, Y, and Z components, the mean 3D position error of each scanbody, and the intra-scanbody distance error were measured using the analysis of variance and the Sheffe's test for multiple comparison.

RESULTS

Statistically significant differences in the accuracy of the impression were observed among the operators for each scanbody, despite the good reliability (Cronbach's [Formula: see text] = 0.897). The mean 3D position error of the digital impression was between 0.041 ± 0.023 mm and 0.082 ± 0.030 mm.

CONCLUSIONS

Within the limitations of this in vitro study, which was performed using a single commercial system for preparing digital impressions and one test configuration, the data showed that the digital impressions had a level of accuracy comparable to that reported in other studies, and which was acceptable for clinical and technological applications. The distance between the individual positions (#36 to #46) of the scanbody influenced the magnitude of the error. The position error generated by the intraoral scanner was dependent on the length of the arch scanned. Operator skill and experience may influence the accuracy of the impression.

In vitro evaluation of prosthodontic impression on natural dentition: a comparison between traditional and digital techniques

OBJECTIVES

The aim of this in vitro study is to evaluate the marginal and internal fit of zirconia core crowns manufactured following different digital and traditional workflows.

METHODS

A 6° taper shoulder prepared abutment tooth was used to produce 20 zirconia core crowns using four different scanning techniques: scanned directly with the extraoral lab scanner, scanned with intraoral scanner, dental impressions using individual dental tray and polyether, dental casts from a polyether impressions. Marginal and internal fits were evaluated with digital photography and the silicone replica method.

RESULTS

Medium marginal gaps were 76,00 μm ± 28.9 for extraoral lab scanner, 80.50 μm ± 36,2 for intraoral scanner, 88.10 μm ± 34,8 for dental impression scan and 112,4 μm ± 37,2 for dental cast scan. Medium internal gaps were 23.20 μm ± 10,3 for extraoral lab scanner, 16.20 μm ± 8.3 for intraoral scanner, 27.20 μm ± 16.7 for dental impression scan and 30.20 μm ± 12.7 for dental cast scan.

CONCLUSION

Internal gap were extensively lower than 70 μm described in literature. Marginal fit was higher than ideal values for all the techniques but within the limit of clinical success. Intraoral scanners obtained the best results for internal gap.

Clinical and radiographic evaluation of single tantalum dental implants: a prospective pilot clinical study

OBJECTIVE

The aim of this prospective pilot clinical case series report was to evaluate, through a clinical and radiographic analysis, the peri-implant bone resorption of the tantalum dental implants (TMT) (Zimmer TMT, Parsippany, NJ, USA) one year after prosthetic rehabilitation.

METHODS

Twenty tantalum dental implants were placed in both maxillas and mandibles of 20 patients. Patients were asked to attend a radiographic and clinical follow-up and their previous clinical records and X-rays were assessed. Bone levels were calculated by digitally measuring the distance from the implant shoulder to the first bone-to-implant on periapical radiographs taken at surgery and after 6 and 12 months of functioning. The Pearson correlation analysis was performed to assess it there was a correlation between the measurement of the marginal bone loss (MBL). The Anova Test with a post-hoc analysis using Bonferroni's test was used to compare the three group (0, 6 months and 12 months).

RESULTS

The mean total MBL for the group 0 months was 0.84 mm (SD 0.21), 6 months was 0.87 mm (SD 0.22) and for 12 months was 0.89 mm (SD 0.23). The values of the Pearson's coefficients showed that the data measurement were positively correlated. The Anova test showed a statistically significant difference between the groups.

CONCLUSION

The statistically significant difference in marginal bone loss can be considered physiological. Within the limits of this study it can be concluded that TMT implants have an excellent bone crest's stability, however, to have most accurate information, will be necessary extend the sample.