This study aimed to review clinical publications involving anterior-region resin-bonded fixed partial dentures to evaluate their survival rates vis-à-vis their materials and design. An electronic search was conducted using PubMed/MEDLINE to identify articles that reported on the longevity of anterior resin-bonded fixed dental prostheses published between 2000 and 2020. Only primary clinical studies that involved a follow-up after at least 3 years were included in this review. A statistical analysis was performed to evaluate resin-bonded fixed dental prostheses’ survival rates in relation to their materials and design. This review ultimately included 23 clinical publications, comprising prospective studies, retrospective studies, and randomized controlled trials. Its statistical analysis estimated the studied prostheses’ 5-year survival rate at 86.2% for metal-framed prostheses, 87.9% for zirconia prostheses, 93.3% for alumina prostheses, 100% for glass or ceramic prostheses, and 81.7% for fiber-reinforced composite restorations. Failure rates did not significantly differ between the different material groups or between the single- and double-retainer groups. Resin-bonded fixed dental prostheses present excellent 5-year clinical longevity in the anterior sector and a favorable benefit/risk/cost ratio. Currently, no consensus has been established on an ideal material for these restorations. Cantilever design tends to limit constraints on the prostheses’ retainers and, thus, increases their survival time. All-ceramic cantilever fixed partial dentures can be considered as a definitive therapy, given their high success and survival rates. They are an optimal solution for adolescents or young adults facing potentially continuous growth.

Thermal and self-curing acrylic resins are frequently and versatilely used in dental medicine since they are biocompatible, have no flavor or odor, have satisfactory thermal qualities and polishing capacity, and are easy and fast. Thus, given their widespread use, their fracture resistance behavior is especially important. In this research work, we comparatively analyzed the fracture resistance capacity of thermo and self-curing acrylic resins in vitro. Materials and Methods: Five prosthesis bases were created for each of the following acrylic resins: Lucitone®, ProBase®, and Megacryl®, which were submitted to different forces through the use of the CS^® Dental Testing Machine, usually mobilized in the context of fatigue tests. To this end, a point was defined in the center of the anterior edge of the aforementioned acrylic resin bases, for which the peak tended until a fracture occurred. Thermosetting resins were, on average, more resistant to fracture than self-curable resins, although the difference was not statistically significant. The thermosetting resins of the Lucitone® and Probase® brands demonstrated behavior that was more resistant to fracture than the self-curing homologues, although the difference was not statistically significant. Thermosetting resins tended to be, on average, more resistant to fracture and exhibited the maximum values for impact strength, compressive strength, tensile strength, hardness, and dimensional accuracy than self-curing resins, regardless of brand.

Aim and Background. The absorption of fluids by denture base materials diminishes the mechanical properties such as hardness, strength, and fatigue limit due to the plasticizing effect of water. This study aimed to evaluate the influence of oral pH on the fracture resistance of prosthetic bases made of three different heat-polymerizable acrylic resin brands: RS Vertex®, Triplex Hot®, and Megacryl®. The strength needed to fracture the resins and the resistance to fracture each resin were evaluated. Methods. Ten prosthesis bases prepared with each brand of resin were subjected to neutral and low pH conditions (pH 7 and pH 4) by submerging them in artificial saliva for 30 days. After exposure, the fatigue resistance of the resins was tested using a Dental CS® Testing Machine. Statistical Analysis Test. The data sets were described quantitatively in terms of mean (M) and standard deviation (SD). Shapiro–Wilk tests and unilateral analysis of variance (ANOVA) were performed and complemented by Tukey’s multiple comparison tests. The effect size (η2), whose cohort points followed Cohen’s recommendations: 0.01 (low), 0.06 (medium), and 0.14 (high), was calculated. The results were considered significant if $p<0.05$ and marginally significant if $p<0.10$ . Results. One-way ANOVA showed that Megacryl® had the highest fracture resistance at pH 7 (52.23 Kgf), compared with Triplex Hot® ( $p<0.001$ ) and RS Vertex® ( $p=0.034$ ). Two-way ANOVA confirmed the interaction between brand and pH ( $p=0.022$ ), also revealing that brands comparison is significant or marginally significant, when pH is not considered (Megacryl® versus Triplex Hot®, $p<0.001$ , and RS Vertex®, $p=0.058$ ; Triplex Hot® versus RS Vertex®, $p=0.051$ ), and pH 7 results were significantly higher ( $p=0.003$ ), even when brands are not considered. Hence, Megacryl® at pH 7 was found to have the highest fracture resistance, detached from other brands and pH values. Conclusion. It can be concluded within the limitations of this study that there are differences in the fracture resistance among the three brands of acrylic resin. Megacryl® was found to have the highest fracture resistance, and Triplex Hot® was the lowest. The results also show that exposure to a low pH environment decreases the fracture resistance of the Megacryl® and RS Vertex® resins.

Background. In the past 20 years, several studies and clinical trials have reported similar results for trans-mucosal implants as compared to submerged implants. Several advantages of immediate loading have been pointed out, such as the reduction of treatment time, trauma reduction, and immediate esthetic and functional improvements. Objectives. The main objective of this study was to clinically evaluate the implant survival rate in patients with total rehabilitation via implants that underwent immediate loading in the past 5 years. Material and methods. A cross-sectional, descriptive, observational analysis was conducted. The implant survival rate for an edentulous maxilla or mandible was assessed with regard to the loading protocol by means of a questionnaire and clinical observation. The study included 103 patients with edentulous jaws rehabilitated with fixed prostheses on implants. Each patient received 4-6 implants. In total, 474 implants were placed. Factors such as the implant survival rate as well as biological and prosthetic complications were evaluated and analyzed statistically. Results. Of the 474 implants initially placed, 458 were considered osteointegrated and 16 were considered lost, which corresponds to a 96.62% implant survival rate. The most common types of failure were prosthetic fractures (46.2%), peri-implantitis (23.1%) and unscrewing (11.5%) in the first 5 years. Conclusions. The rate of osseointegration for implants placed under immediate loading was extremely high, in accordance with the previously published studies, which led us to conclude that currently, this is a surgical procedure with a high rate of success and high predictability.

Aroso C, et al. J Adv Prosthodont. 2016 Feb;8(1):21-29. http://dx.doi.org/10.4047/jap.2016.8.1.21

With continuing technological developments, there have been advances in the field of fixed prosthetics, particularly in impression-taking techniques. These technological advances mean that a wide variety of diagnostic and/or rehabilitation possibilities can be explored without the need for physical models. The aim of this study was to evaluate the accuracy of three intraoral scanners used in oral implant rehabilitation using an extraoral scanner as a reference and varying the scanning area. Three models representing different clinical scenarios were scanned 15 times by each intraoral scanner and three times by the extraoral scanner. The readings were analyzed and overlaid using engineering software (Geomagic^® Control X software (Artec Europe, Luxembourg)). Statistically significant differences in accuracy were found between the three intraoral scanners, iTero^® (Align Technology Inc., San Jose, CA, USA), Medit^® (Medit^®: Seoul, Korea), and Planmeca^® (Planmeca^®: Helsinki, Finland). In all clinical scenarios, the iTero^® scanner had the best trueness (24.4 μm), followed by the Medit^® (26.4 μm) and Planmeca^® (42.1 μm). The Medit^® showed the best precision (18.00 μm) followed by the iTero^® (19.20 μm) and Planmeca^® (34.30 μm). We concluded that the iTero^® scanner had the highest reproducibility and accuracy in the clinical setting.