Intraoral ultrasonography image registration for evaluation of partial edentulous ridge: A methodology and validation study.

OBJECTIVES: Ultrasound (US) reveals details for diagnosing soft- and hard-tissue dimensions around teeth, implants, and the edentulous ridge, not seen in 2D radiographs. Co-registering free-hand US scans with other 3D modalities presents reliability challenges. This study first aims to develop and validate a registration method to longitudinally reproduce US images of the jawbone on a simulator. In addition, it also evaluates the degree of the anatomical match in humans between US images acquired by the proposed registration method and the commonly used freehand acquisitions in comparison to cone beam computed tomography (CBCT) and intra-oral optical scan (IOS), used as references. METHODS: A previously introduced ultrasound phantom was employed as a CBCT-US hybrid, suitable for training and technique development of US guides in edentulous ridges. After establishing feasibility in the phantom, the methodology was validated in a cohort of 24 human subjects (26 cases). Soft tissues were delineated on US and IOS, and hard tissues on US and CBCT. US accuracy and repeatability from both guided and freehand scans (non-guided) was assessed as the average distance between US and the references. RESULTS: Guided US images resembled the references more closely than freehand (non-guided) scans. Notably, delineation of soft and hard tissues was significantly more accurate when employing guides. In the phantom, guided scans exhibited an absolute mean deviation of 81.8 µm for gingiva and 90.4 µm for bone, whereas non-guided scans showed deviations of 150.4 µm and 177.2 µm, respectively. Similarly, in vivo, guided US outperformed non-guided US, with gingiva deviations of 125 µm and 196 µm, and bone deviations of 354 µm and 554 µm, respectively. CONCLUSIONS: By using a registration method, guided US scans improved repeatability and accuracy of mapping hard and soft tissue of the edentulous ridge when compared to non-guided scans. CLINICAL RELEVANCE: This guided US imaging method could lay the foundation for longitudinal evaluation of tissue behavior and dimensional changes with improved accuracy.

Influence of scanbody design and intraoral scanner on the trueness of complete arch implant digital impressions: An in vitro study.

This study aimed to compare the accuracy of full-arch digital implant impressions using seven different scanbodies and four intraoral scanners. A 3D-printed maxillary model with six implants and their respective multi-unit abutments was used for this study. Seven scanbodies (SB1, SB2, SB3, SB4, SB5, SB6, and SB7) and four intraoral scanners (Primescan®, Omnican®, Trios 3®, and Trios 4®) were assessed. Each combination group was scanned ten times and a dental lab scanner (D2000, 3Shape) was used as a reference. All scans were exported as STL files, imported into Convince software (3Shape) for alignment, and later into Blender software, where their 3D positions were analyzed using a Python script. The 3D deviation, angular deviation, and linear distance between implants #3 and #14 were also measured. Accuracy was measured in terms of "trueness" (scanbody 3D deviation between intraoral scan and desktop scan). Kruskal-Wallis followed by the Bonferroni correction was used to analyze the data (⍺ = .05). The study found statistically significant differences in digital impression accuracy among the scanners and scanbodies (p<0.001). When comparing different intraoral scanners, the Primescan system showed the smallest 3D deviation (median 110.59 µm) and differed statistically from the others, while Trios 4 (median 122.35 µm) and Trios 3 (median 130.62 µm) did not differ from each other (p = .284). No differences were found in the linear distance between implants #3 and #14 between Trios 4, Primescan, and Trios 3 systems. When comparing different scanbodies, the lowest median values for 3D deviation were obtained by SB2 (72.27µm) and SB7 (93.31µm), and they did not differ from each other (p = .116). The implant scanbody and intraoral scanner influenced the accuracy of digital impressions on completely edentulous arches.

Volumetric Outcomes of Peri-implant Soft Tissue Augmentation with a Xenogeneic Cross-Linked Collagen Scaffold: A Comparative Clinical Study.

Performing soft tissue augmentation (STA) at implant sites to improve esthetics, patient satisfaction, and peri-implant health is common. Several soft tissue grafting materials can be used to increase soft tissue thickness at the second-stage surgery, including human dermal matrices and xenogeneic collagen scaffolds. This study assessed and compared the volumetric outcomes, from second-stage surgery to crown delivery, around implants that received STA with a xenogeneic cross-linked collagen scaffold (XCCS) vs nonaugmented implant sites. Thirty-one patients (31 implant sites) completed the study. Intraoral digital scans were taken at the second stage and prior to crown delivery, and the STL files were imported in an image-analysis software to assess volumetric changes. XCCS-augmented implants showed significantly greater volumetric changes compared to control sites, which showed volume loss. The mean thickness of the XCCS-augmented area was 0.73 mm. There was no difference in patient-reported esthetic evaluations between groups. STA with XCCS provided significantly greater volumetric outcomes compared to nonaugmented sites. Further studies are needed to evaluate the long-term behavior of the augmented peri-implant mucosa and the effects of STA on peri-implant health.

Digital planning for two-implant-supported overdenture and bone reduction guide using cone-beam computed tomography: Simple features for predictable outcomes.

The two-implant-supported mandibular overdenture is considered a reliable treatment option to restore masticatory function. Digital planning has been shown to improve the precision and accuracy of the surgical procedure. The outcomes are indeed pertinent to the ideal three-dimentional positioning of the implant placement. Recently, the uses of cone-beam computed tomography (CBCT) and intraoral scan have improved greatly the workflow of digital planning; however, the sophisticated technology caused confusion among clinicians. The purpose of this case series was to exhibit the efficacy of a bone-supported guide in applying simultaneous implant placement and bone reduction, solely based on CBCT data. The bone reduction can therefore be determined accordingly, by adding windows to the guide, allowing the clinician to decide the amount of bone reduction as well as the location for implant placement. This novel surgical guide would not only fit properly on the bone but also provide the benefits of less-invasive surgery and the opportunity to place implants parallel. The  digital workflow described not only simplifies the fabrication process but also yields predictable surgical outcomes.

Fracture Load of Monolithic CAD/CAM Ceramic Crowns Placed on Different Implant Abutments.

PURPOSE: To evaluate the fracture load of monolithic, single-tooth implant-supported crowns cemented on solid or Ti-base (Variobase C) abutments. MATERIALS AND METHODS: Besides abutment types (solid and Ti-base abutments), two ceramic systems (IPS e.max CAD and Zirconia inCoris ZI) and two occlusal thicknesses (0.5 and 1.5 mm) were also investigated in this study. In total, eight groups (n = 8) with 64 maxillary second premolar crowns were fabricated. All the crowns were cemented with resin cement, and the screw accesses in Ti-base groups were sealed with composite resin. After mechanical cycling, the specimens were submitted to fracture load test with the maximum force recorded in Newtons (N). Three-way analysis of variance (ANOVA) and Tukey post hoc test were used for statistical analyses (α = .05). RESULTS: Both the abutment type (P = .0001) and the ceramic system (P = .0001) significantly affected the results. Screw-access channels reduced the fracture load of crowns by half compared to those cemented on solid abutments. The 1.5-mm and 0.5-mm zirconia crowns placed on solid abutments had similar highest fracture loads, while the e.max CAD groups positioned on Ti-base abutments showed significantly lower values compared with other groups. CONCLUSION: The screw access reduces the resistance of crowns supported by Ti-base abutments compared to crowns cemented on solid abutments. The inCoris ZI showed a higher fracture load than the IPS e.max CAD regardless of the abutment type and thickness.

Open-sleeve templates for computer-assisted implant surgery at healed or extraction sockets: An in vitro comparison to closed-sleeve guided system and free-hand approach.

OBJECTIVE: A buccal opening guide provides better view and better irrigation. The aim of this study was to investigate the accuracy of this open-sleeve system. MATERIAL AND METHODS: Thirty duplicated maxillary models, each with six extraction sockets and four healed sites, were used. Based on the same digital plan, three modalities, sCAIS with open-sleeves, closed-sleeves, and free-hand approach, were used to place implants. The global, horizontal, depth, and angular deviations between the virtual and actual implant positions were measured. RESULTS: Both sCAIS groups exhibited better accuracy than the free-hand group in two clinical scenarios. At healed sites, the closed-sleeve group showed a significantly fewer error than the open-sleeve group in global apical (0.68 ± 0.33 vs. 0.96 ± 0.49 mm), horizontal coronal (0.28 ± 0.15 vs. 0.44 ± 0.25 mm), horizontal apical (0.64 ± 0.32 vs. 0.94 ± 0.48 mm), and angular deviations (1.83 ± 0.95 vs. 2.86 ± 1.46°). For extraction sockets, the open-sleeve group exhibited fewer deviations than the closed-sleeve group in terms of global (coronal: 0.77 ± 0.29 vs. 0.91 ± 0.22 mm; apical: 1.08 ± 0.49 vs. 1.37 ± 0.52 mm) and horizontal (coronal: 0.60 ± 0.24 vs. 0.86 ± 0.20 mm; apical: 0.95 ± 0.50 vs. 1.32 ± 0.51 mm) deviations. However, the closed-sleeve group was more accurate in the depth control (0.26 ± 0.20 vs. 0.40 ± 0.31 mm). CONCLUSION: In this in vitro investigation, open-sleeve sCAIS proved better accuracy than free-hand surgery for both delayed and immediate implant placement. Compared with a closed-sleeve sCAIS system, open sleeve have the potential of providing better outcomes in extraction sockets but not in healed sites.

Early soft tissue changes following implant placement with or without soft tissue augmentation using a xenogeneic cross-link collagen scaffold: A volumetric comparative study.

OBJECTIVE: Soft tissue augmentation (STA) at implant sites has the potential of improving peri-implant health, esthetics, and marginal bone level stability. The present study aimed at evaluating the volumetric changes occurring following implant placement in sites that received STA compared to non-augmented sites. METHODS: A total of 26 subjects received a dental implant in a posterior edentulous site. Simultaneous STA with a xenogeneic cross-linked collagen scaffold was performed for the first 13 patients, while the remaining subjects served as the negative control. An intraoral optical scanner was used at baseline and at 12 weeks to generate digital models. RESULTS: The mean volume (Vol) gain of the test group was 38.43 mm3 , while a mean Vol of -16.82 mm3 was observed for the control group (p < 0.05). The mean thickness of the reconstructed volume (ΔD) was 0.61 and -0.24 mm, for the test and control group, respectively (p < 0.05). Higher linear dimensional changes were observed for the test group (p < 0.05), while no significant differences were observed in terms of keratinized mucosa width and pocket depth changes between the two groups. CONCLUSIONS: Simultaneous STA with xenogeneic collagen scaffold obtained statistically significant higher volumetric outcomes compared to the non-augmented group. CLINICAL SIGNIFICANCE: STA at the time of implant placement using a xenogeneic cross-linked collagen scaffold can prevent remodeling of the ridge during the first 12 weeks, as compared to non-grafted implant sites.

Digital Immediate Complete Denture for a Patient with Rhabdomyosarcoma: A Clinical Report.

Fabricating an immediate complete denture can be very challenging in some clinical situations. This clinical report describes a digital workflow to fabricate a printed maxillary immediate complete denture for a patient with a severely compromised maxilla. Digital data obtained by using an intraoral scanner was utilized to reconstruct the three-dimensional (3D) image of the jaws at the desirable vertical dimension of occlusion. After performing the virtual teeth extraction and alveoloplasty, the denture base and teeth were designed. The resulting data were exported to a 3D printer for denture fabrication and the 3D printed (additively manufactured) denture was successfully inserted immediately after the surgery. After initial healing and confirmation of good retention and function, a new printed denture was fabricated by digitally duplicating the relined denture maintaining the same teeth positions but adjusting the base to a new intraoral scan of the healed ridge.