Malpositioned Implant in the Esthetic Area: The Peri-Implant Plastic Surgery and Angulated Welded Abutment Approach.

PURPOSE: To describe the treatment of malpositioned implants in the esthetic area using the angulated welded abutment (AWA) approach together with peri-implant soft tissue surgery. MATERIALS AND METHODS: A clinical case with extreme buccal angulation of two implants in the anterior maxilla was used to illustrate the AWA technique. After implant impression-taking, digital analysis was used to determine the ideal prosthetic angulation of the abutment and the ideal position of its screw hole in relation to the gingival margin of the adjacent teeth. The AWA was designed in two combinable components that were meant to be welded together. Before the welding process, an angulated screw was included in the abutment. Since the angulated screw was inside the abutment, the screwdriver hole could be designed as narrow as possible and put in an ideal position. After periodontal and peri-implant surgery were carried out, the AWA was applied to the implants. RESULTS: The AWA allowed correction of the prosthetic axis. Moreover, relocation of the screw hole allowed the gingival tissue to creep over the abutment. In this way, a new esthetic restoration can be placed after the mucogingival surgery. CONCLUSION: The excessive misangulation of the implants was efficiently recovered. Further studies are needed to evaluate long-term clinical success, and standardization of this technique is required for routine clinical use. Int J Prosthodont 2023;36:228-232. doi: 10.11607/ijp.759.

In vitro 2D and 3D roughness and spectrophotometric and gloss analyses of ceramic materials after polishing with different prophylactic pastes.

STATEMENT OF PROBLEM: The effect of prophylactic polishing pastes on composite resin materials has been extensively investigated, but little is known about their effect on ceramic materials. PURPOSE: The purpose of this in vitro study was to evaluate the effect of prophylactic polishing pastes on the 2D and 3D roughness, translucency, and gloss of different ceramic materials. MATERIAL AND METHODS: A total of 120 flat specimens (thickness: 2 mm) obtained from computer-aided design and computer-aided manufacturing (CAD-CAM) blocks of leucite glass-ceramic (Empress CAD), lithium disilicate glass-ceramic (e.max CAD), and zirconia (Zenostar MT) were glazed and sintered. Forty specimens from each material were then divided into 4 groups and polished with Cleanic fine, Nupro fine, or Proxyt fine pastes, leaving the control group untreated. The specimens were polished for 2 minutes with a prophylaxis cup mounted on a handpiece, applying a constant load of 3.9 N at 2000 rpm. Surface roughness was measured by using a contact profilometer and a 3D optical profilometer. The translucency parameter and gloss value were calculated by using a spectrophotometer and a glossmeter. One specimen per group was observed by scanning electron microscopy at ×200 magnification. Differences in means were compared by using 2-way ANOVA followed by the Tukey honestly significant difference (HSD) test (α=.05). RESULTS: The 2D roughness of Empress was lower than that of e.max (P<.05) and was increased by using Cleanic fine and Nupro fine pastes (P<.05). The translucency parameter values of Empress and Zenostar decreased with the use of Nupro fine paste (P<.05). Zenostar showed the lowest translucency (P<.05). The effect of prophylactic polishing pastes on gloss was minimal (P>.05). The gloss of Empress was higher than that of Zenostar and e.max (P<.05). The Pearson correlation showed that gloss and surface roughness were correlated (P<.001). CONCLUSIONS: Polishing procedures can alter the surface of a ceramic restoration.

Manufacturing of Metal Frameworks for Full-Arch Dental Restoration on Implants: A Comparison between Milling and a Novel Hybrid Technology.

PURPOSE: To determine the trueness and precision of frameworks manufactured with a selective laser melting/milling hybrid technique (SLM/m) and conventional milling by comparing the implant-platform/framework interface with those of the original computer-aided design (CAD). MATERIALS AND METHODS: Using a virtual 6-implant-supported full-arch framework CAD drawing, 27 titanium replicas were manufactured by 3 independent manufacturing centers (n = 9/center) using a hybrid SLM/m technology (labs 1 and 2) or the conventional milling technique (lab 3). Using an opto-mechanical coordinate measuring machine, the frameworks' misfit distribution and patterns were analyzed, and the position error between paired platform positions within each framework was evaluated to calculate the misfit tendency for each group. A multilevel analysis using a mixed-effects model was conducted (α = 0.05). The trueness was evaluated as the dimensional difference from the original, while the precision as the dimensional difference from a repeated scan. RESULTS: The 3 dimensional misfits differed significantly among the 3 groups, with the milled group exhibiting the least accurate outcome (p = 0.005). The mean 3D positioning errors ranged from 8 to 16 µm and from 9 to 22 µm for the SLM/m technique (labs 1 and 2, respectively), and from 20 to 35 µm for conventional milling (lab 3). Regarding the misfit distribution pattern, the misfit increased with the distance between paired platform positions in all groups. CONCLUSIONS: All groups had 3D misfits well within the error limits reported in the literature. The 3D misfits of new hybrid (SLM/milling) and conventional (milling) procedures differed significantly among them, with the milling technique the less accurate and precise. The largest errors in all groups were found between the most distant implants, resulting in a correlation between the framework span and the inaccuracies.

Digital bar prototype technique for full-arch rehabilitation on implants.

BACKGROUND AND OVERVIEW: The aim of the authors in this case report was to describe a new approach to using the digital bar prototype technique for complete digital full-arch implant rehabilitation. Two combinable structures were used during the same visit as prototypes to simultaneously test the implant locations and the prosthetic parameters. Then the structures were joined together to form the final prosthesis. CASE DESCRIPTION: After the implant integration with the immediate provisional restoration, 3 sets of digital impressions were obtained to obtain a master digital model (MDM). A stereolithographic model with implant analogs was printed on the basis of the MDM. A titanium bar with implant connections and a functional resin structure were milled on the basis of the MDM and used as prototypes. To check the accuracy of the implant impression, the titanium prototype was tried in, and clinical and radiographic tests were performed. Then the resin prototype was slid into the positional prototype and fitted to the patient, and the esthetic and occlusal properties were evaluated and refined. Definitive restoration was obtained by luting the 2 prototypes together and finalizing the prosthesis with pink resin. CONCLUSIONS AND PRACTICAL IMPLICATIONS: The prototypes allowed the clinician to simultaneously verify the accuracy of the digital impressions and test the prosthetic parameters in 1 visit. Moreover, they were used to create the final restoration. The digital bar prototype technique also allowed for the reduction of clinical and laboratory time in a full-arch rehabilitation on implants. Nevertheless, obtaining a full-arch impression in an edentulous arch can be challenging, and further studies are necessary to evaluate the long-term success of this technique.

Implant Digital Impression in the Esthetic Area.

The aim of this report is to describe two standardized protocols for digital impression when implant support rehabilitation is used in the esthetic area. The two techniques were used to transfer all provisional crown parameters to definitive restorations in different clinical scenarios. In the direct technique, an impression (STL1) is made of the provisional restorations attached to the implants, with surrounding gingival tissue. The second scan (STL2) captures the sulcular aspect of the peri-implant soft tissue immediately after removal of the provisional restoration. The last impression (STL3) of the complete arch is made with a standardized scanbody attached to the implant to capture the 3D location of the implant. The direct technique is indicated when the peri-implant soft tissues are stable upon removal of the provisional restoration. The indirect technique is used when the gingival tissue collapses rapidly after the removal of the provisional crown. The impressions of the provisional restoration and the position of the implant are similar to those obtained with the direct technique, and the shape of the peri-implant tissue is extrapolated from the negative shape obtained from making the digital impression when the provisional restoration is taken out of the mouth. Finally, in both techniques the 3 scans are superimposed to obtain a file, which contains the details of the peri-implant soft tissue. The direct and indirect digital techniques allowed realization of a predictable definitive restoration in the esthetic zone in different clinical scenarios, reducing the duration of clinical procedures.

The prototype concept in a full digital implant workflow.

BACKGROUND: The aim of this case report is to describe the innovative concept of a prototype use in a digital implant workflow. A prototype is required for simultaneous evaluation of the accuracy of a dental impression and esthetic and functional parameters before final framework realization. CASE DESCRIPTION: Three digital impressions were obtained to create a master file, which contained information on the 3-dimensional (3D) position of the implant, the gingival architecture, and the esthetic and functional features of the provisional restoration. A stereolithographic master model (SMM) featuring implant analogs was 3D printed. Two prototypes were realized with the use of 2 different modalities. The first resin prototype (A), which lacked implant connections, was produced with the use of a certified digital workflow process. The titanium connections were luted onto the SMM. The second resin prototype (B), considered experimental, was a single piece with milled implant connections. Both prototypes were tested in the patient by means of visual inspection, finger pressure testing, screw resistance testing, and periapical radiography. In the case of accurate fit of prototype A or B on the SMM and misfit in the patient, the impression should be invalidated. For prototype B, in the case of proper fit in the patient and misfit on the SMM (because of the occurrence of an error during 3D printing, incorrect analog position, or both), the impression should be validated, but the model should be adapted. CONCLUSIONS AND PRACTICAL IMPLICATIONS: The use of a prototype allows the clinician to simultaneously test implant position and esthetic and functional parameters. However, a single-structure prototype could be preferable for the identification of impression inaccuracy.

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.

A fully digital approach to replicate functional and aesthetic parameters in implant-supported full-arch rehabilitation.

PURPOSE: The aim of this technical procedure was to use a fully digital technique (FDT) for full-arch implant support rehabilitation. The FDT was used to transfer the provisional restoration parameters to definitive restorations using intraoral scanners. METHODS: Three sets of digital impressions were obtained. Through the first set, standard tessellation language 1 (STL1), provisional restorations screwed to implants and the surrounding gingival tissue was captured. STL2 consisted of intraoral scans of standardized scanbodies screwed to implants to collect 3D positioning data of implants. STL3 included the digital impression of provisional restoration out of the mouth in order to capture the gingival architecture and the peri-implant soft tissue that was not possible to transfer with the previous impressions. STL1, STL2, and STL3 were combined using computer-aided design (CAD) functions into a single file, STL4. Thus, STL4 contained information on the 3D implant positions, soft tissue architectures, occlusal relationships, correct occlusal vertical dimension and aesthetic features. Using STL4, the master models with implant analogues were 3D printed. Computer-aided design and computer-aided manufacturing milled (CAD/CAM-milled) aluminium bars and a resin prototype were produced to test the accuracy and the functional and aesthetic parameters. Titanium frameworks were digitally designed using STL4, milled using CAD/CAM, and finalized with pink resin and resin teeth. CONCLUSION: The FDT provided an effective fully digital protocol to capture all information for provisional full-arch implant restorations using an intraoral scanner and transfer that information to definitive restorations.