Optimal impression materials for implant-supported fixed complete dentures: A systematic review and meta-analysis.

STATEMENT OF PROBLEM: Although polyvinyl siloxane (PVS) materials and polyether (PE) materials have been the recommended materials for making impressions for implant-supported fixed complete dentures (IFCDs), a consensus regarding the optimal impression materials has yet to be established. PURPOSE: The purpose of this systematic review and meta-analysis was to evaluate the effect of impression materials on the accuracy of conventional impressions for IFCDs and to provide guidance for selecting the optimal impression material. MATERIAL AND METHODS: The PubMed, Web of Science, and Embase databases were searched and supplemented via hand searches. Studies comparing the accuracy of conventional impressions for IFCDs by using PVS and PE materials with either direct (open-tray) or indirect (closed-tray) techniques were included. Linear distance deviations and angular deviations between adjacent implants were evaluated. The mean difference (MD) with a 95% confidence interval (CI) was calculated for continuous data. A subgroup analysis was conducted to evaluate the impact of implant angulation (α=.05). RESULTS: Among the 597 publications identified, 27 in vitro studies were included for qualitative analysis, and 12 were included for quantitative analysis. The general analysis revealed no significant differences in linear distance and angular deviations between the 2 impression materials with the direct or indirect technique. The subgroup analysis found that a statistically significant difference in linear distance deviations was found when implants were placed at an angle greater than 15 degrees, favoring PE materials when using the direct technique (P=.010, MD: 32.54 µm; 95% CI: 6.83 to 58.24) and indirect technique (P=.020, MD: 138.15 µm, 95% CI: 19.17 to 257.13). However, only 2 relevant studies assessed the indirect technique. CONCLUSIONS: When providing IFCDs, conventional impressions obtained by using PVS and PE materials were found to have similar accuracy in most scenarios. PE materials yielded better outcomes when implants were placed at an angle greater than 15 degrees.

Influence of ambient light conditions on intraoral scanning: A systematic review.

PURPOSE: To systematically assess the influence of ambient light on the accuracy and scanning time of intraoral scanning. STUDY SELECTION: The present systematic review (CRD 42022346672) was registered at the International Prospective Register of Systematic Reviews (PROSPERO) and was performed based on the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020. Electronic searches were conducted using PubMed, Web of Science, and EMBASE, complemented by gray literature, references, and citations of the included studies. The primary outcome was accuracy, and the scanning time was a secondary outcome. Owing to the high heterogeneity, the pooled data were analyzed descriptively. RESULTS: Six in vitro and two in vivo experiments were performed. Three in vitro studies reported both the accuracy and scanning time of the intraoral scans, whereas the remaining studies exclusively evaluated the accuracy. The studies mainly investigated the influence of illumination levels (0-11000 lux) on intraoral scanning. Intraoral scans revealed optimal accuracy at 1000-lux illumination for complete-arch dentition scans, whereas the influence of illumination levels on 4-unit or shorter scans was not clinically significant. The intraoral scans obtained using confocal microscopy were less affected by the illumination levels than those obtained using the active triangulation technique. Furthermore, the scanning time tended to increase with increasing illumination. CONCLUSIONS: Evidently from the limited number of studies conducted, ambient light illumination had considerable influence on the accuracy and scanning time of intraoral scanning, which appeared to be related to the scanning range and imaging technology.

Influence of intraoral conditions on the accuracy of digital and conventional implant impression techniques for two-implant-supported fixed dental prostheses.

PURPOSE: To compare the trueness and precision of different impression techniques for two-implant-supported fixed dental prostheses between extraoral and intraoral conditions at different locations. METHODS: Six volunteers participated in this study. A resin block with two parallel analogs was fabricated as an implant site simulator (ISS). The ISS was bonded to a molded ethylene vinyl acetate sheet to create a reference model. For each participant, four reference models were prepared based on the locations of the ISSs: maxillary posterior/anterior region (MaxP/MaxA) and mandibular posterior/anterior region (ManP/ManA). Five impressions were taken extraorally using the open-tray (conventional implant impression technique, CIT) and intraoral scanning (digital implant impression technique, DIT) techniques. The reference models were positioned in the participants' mouths, and impressions were obtained intraorally using the CIT and DIT. The interanalog distance (d) and angulation (θ) were measured to calculate trueness (Δd, Δθ) and precision (dP, θP). Two-way ANOVA and t tests were performed (α=0.05). RESULTS: For the DIT, under intraoral conditions, the Δd and Δθ in MaxP and Δθ in ManP were significantly higher than those under extraoral conditions. For the CIT, under intraoral conditions, the Δd and Δθ in ManA and ManP and Δθ in MaxP were significantly lower than those under extraoral conditions. No significant differences in the dP and θP of either DIT or CIT were observed between the two conditions. CONCLUSIONS: Intraoral conditions affected the trueness of DIT and CIT in different regions but had no influence on precision.

Kindler syndrome protein Kindlin-1 is mainly expressed in adult tissues originating from ectoderm/endoderm.

Mutations of integrin-interacting protein Kindlin-1 cause Kindler syndrome and deregulation of Kindlin-1 is implicated in human cancers. The Kindlin-1-related diseases are confined in limited tissue types. However, Kindlin-1 tissue distribution and the dogma that governs Kindlin-1 expression in normal human body are elusive. This study examined Kindlin-1 expression in normal human adult organs, human and mouse embryonic organs by immunohistochemical analyses. We identified a general principle that the level of Kindlin-1 expression in tissues is tightly correlated with the corresponding germ layers from which these tissues originate. We compared the expression of Kindlin-1 with Kindlin-2 and found that Kindlin-1 is highly expressed in epithelial tissues derived from ectoderm and endoderm, whereas Kindlin-2 is mainly expressed in mesoderm-derived tissues. Likewise, Kindlin-1 was also found highly expressed in endoderm/ectoderm-derived tissues in human and mouse embryos. Our findings indicate that Kindlin-1 may play an importance role in the development of endoderm/ectoderm related tissues.