ABSTRACT
The cantilevered fixed partial denture (CFPD) is gaining recognition as a sound method of replacing missing teeth in the posterior sector. The purpose of this case report is to demonstrate that this type of restoration can be performed in a single appointment. A 39-year-old patient presented herself to the dental department; she showed agenesis of the two first maxillary premolars with a totally closed mesio-distal gap and a recent loss of the 2 s maxillary premolars. This case report concerns the replacement of the upper left second premolar. The patient was treated with a mesial CFPD resting on an "onlay-like" retainer on the first molar and replacing the missing premolar with a cantilevered pontic. The dimensions of the connection's cross-section were maximized as much as possible (>20 mm2). The restoration was designed and produced using chairside CAD-CAM from a milled-reinforced glass-ceramic block (Emax CAD, Ivoclar Vivadent). The aesthetic and functional integration of the prosthesis was successful. The patient was examined at 11 months for a follow-up. At this early stage, satisfactory dental hygiene was observed, associated with a smooth prosthetic fit, no periodontal inflammation, normal probing, and no abnormal dental mobility.
ABSTRACT
Statement of problem: Innovations in intraoral scanner (IOS) technology are opening up ever more indications for computer-aided design and manufacturing (CAD-CAM). The manufacturers claim that the latest generations of scanners allow the digitizing of root canal preparations. However, there is a lack of studies evaluating the quality of the optical impressions made for this type of treatment. Purpose: The purpose of this study was to evaluate the measurement error of 4 IOSs and a laboratory scanner used for the digitizing of root canal preparations and to highlight the effect of the presence or absence of adjacent teeth on the quality of the digital model. Material and methods: Two models: one presenting adjacent teeth, one without adjacent teeth, both presenting a 10 mm deep nominal conical pit mimicking a root canal preparation were fabricated. Each model was scanned 10 times with a laboratory scanner (E3) and 4 intraoral scanners (Primescan, Omnicam, TRIOS 4, and Medit i700). The digital models were then exported as standard tessellation language (STL) files and analyzed to evaluate the mean measurement error of the digitizing of the root preparation at three different depths: 0-3 mm, 3-6 mm, and 6-9 mm. Significant differences were assessed with a 1-way ANOVA test and the pairwise comparison between scanners was done by Tukey's multiple comparison test. Results: Statistical differences were found between scanners (P < 0.05). The mean measurement error ranged from 9.8 ± 0.5 µm with the Medit i700 to 28.2 ± 10 µm with the E3. The E3 and Omnicam scanners were in some cases incapable of digitizing the conical preparation in its entirety. The group Primescan, TRIOS 4, and Medit i700 showed minimally significant differences. The presence of adjacent teeth had a negative effect on the model quality for some scanners, mainly because of the obstruction of the IOS's head. Conclusions: Significant differences were found among the dental scanners used for digitizing root canal preparations. Optical impressions with modern intraoral scanners seem to be an adapted method of registration of root canal preparation for post-and-copings of post-and-cores fabrication.
ABSTRACT
The aim of this systematic review was to determine the optimal printing parameters for the producing of fused deposition modeling (FDM) 3D-printed polyetheretherketone (PEEK) elements with mechanical properties suitable for dental restorations. Indeed, the mechanical properties are a critical prerequisite for the study of other parameters, such as physical, aesthetic and biological properties. An exhaustive electronic search was carried out in the PubMed, Embase and Web of knowledge databases to gather all the studies evaluating the influence of the printing parameters on the obtained mechanical properties of FDM 3D-printed PEEK elements were selected. Initially, the search resulted in 614 eligible papers. Independent screenings of the abstracts were performed by two authors to identify the articles related to the question. Twenty-nine studies were selected, of which eleven were further excluded after reading of the full text, and finally, eighteen articles were included in this review. The studies were difficult to compare due to the variability of the printing parameters and the types of PEEK. However, it seems interesting to use a high infill rate, a high chamber temperature close to that of the printing temperature and a heat post-treatment to obtain 3D PEEK elements presenting properties adapted to use as dental restorations. The analysis of the available literature suggested that the properties of PEEK could make it an interesting material in dental restorations to be performed with FDM additive manufacturing.
ABSTRACT
STATEMENT OF PROBLEM: The quality of the digital cast obtained from an intraoral scanner is an important comparison parameter for computer-aided design and computer-aided manufacturing (CAD-CAM) restorations. However, data on cast quality are typically provided by manufacturers, and objective evaluation of these devices is lacking. PURPOSE: The purpose of this in vitro study was to build an evaluation protocol of 8 intraoral scanners by using an objective method for a small-scale model equivalent in size to a 4-tooth wide cast. In addition, a laboratory scanner was included to compare the performance of intraoral and extraoral devices. MATERIAL AND METHODS: An 8-mm-thick zirconia gauge block was scanned 10 times with a laboratory scanner (Iscan D104) and 8 intraoral scanners (Omnicam, Primescan, Itero element 5D, CS 3600, TRIOS 3, Emerald, Planscan, and Medit i500). The obtained digital casts were extracted as standard tessellation language (STL) files and analyzed to evaluate the digitizing noise, dimensional trueness, and dimensional precision of each scanner. After validation of the normal distribution of the digitizing noise, dimensional trueness, and precision test results for each scanner with the Shapiro-Wilk test (α=.05), differences were determined with a 1-way ANOVA test. RESULTS: Statistical differences were found between scanners (P<.05). The digitizing noise ranged from 3.2 ±0.6 µm with the Primescan to 15.5 ±2.5 µm with the Planscan. The dimensional trueness ranged from 19.1 ±11.5 µm for the CS3600 to 243.8 ±33.6 µm for the Planscan. The dimensional precision ranged from 7.7 ±2.4 µm for the Primescan to 53.7 ±3.4 µm for the Emerald. The group Iscan D104, Primescan, Itero 5D, CS3600, and TRIOS 3 showed minimally significant differences. CONCLUSIONS: Significant differences were found among the intraoral scanners for small-scale scans. The objective methodology of using a gauge block provided coherent and repeatable results.
