Six-year clinical outcomes of implant-supported acrylic vs. ceramic superstructures according to the All-on-4 treatment concept for the rehabilitation of the edentulous maxilla

Outcomes that may affect implant and prosthesis survival and complications in maxillary fixed prosthesis supported by four or six implants: A systematic review and meta-analysis

Objective

To investigate whether the clinical and radiographical outcomes are affected when four or six implants support the maxillary fixed complete denture (FCD).

Materials and methods

This study was registered on PROSPERO (CRD42021226432) and followed the PRISMA guidelines. The focused PICO question was, "For an edentulous maxillary patient rehabilitated with an implant-supported fixed prosthesis, do the clinical and radiographical outcomes differ when four or six implants support the prosthesis ". A thorough search of the relevant studies was designed and performed electronically. The survival rate of implant and prosthesis, marginal bone loss, and complications (mechanical and biological) were the primary outcomes, whereas implant distribution and using the surgical guide, follow-up, and framework material were evaluated as secondary outcomes.

Results

Out of 1099 articles initially retrieved, 53 clearly stated the outcomes of interest and were included in this study. There were no significant differences in implant and prosthesis survival, technical/mechanical complications, and biological complications between the 4-implant group (4-IG) and the 6-implant group (6-IG). However, marginal bone loss (MBL) was significantly higher in the 4-IG (p < 0.01). The surgical guide and follow-up period did not significantly affect implant/prosthesis survival. Additionally, using the CAD/CAM milled framework and anteroposterior implant distribution were associated with significantly higher implant survival in the 6-IG (p < 0.01).

Conclusion

The findings of this study indicated that having a greater number of implants, as seen in the 6-implant group, can lead to a decrease in technical and biological complications and reduce marginal bone loss. It is worth noting that factors such as using CAD/CAM frameworks and the anteroposterior distribution of implants were recognized as important in improving implant survival rates when more implants are present.

A Retrospective Evaluation of 5 Years of Clinical Results of Metal-Ceramic vs. Monolithic Zirconia Superstructures in Maxillary All-on-4TM Concept

The aim of the current study was to present the clinical and radiological outcomes of monolithic zirconia superstructures compared to the metal-ceramic ones in the All-on-4 concept for the prosthetic rehabilitation of the maxillae. A total of 30 patients were subdivided into groups according to their superstructure type (metal-ceramic (n = 15) or monolithic zirconia (n = 15)). All implants were functionally loaded within 24 h after insertion with provisional acrylic superstructures. Prosthetic complications, marginal bone loss, plaque accumulation, probing pocket depth, bleeding on probing, and bite force were documented over a period of 5 years. Marginal bone loss around the implants of the ceramic group remained well over the five years (1.21 ± 0.23 mm). However, marginal bone loss was significantly lower around the implants in the monolithic zirconia group (0.22 ± 0.14 mm) (p < 0.001). Bleeding on probing, plaque accumulation, and probing pocket depth values were correlated with marginal bone loss. Among all evaluated parameters, no differences could be detected in terms of the angulation of the implants. Detachment or chipping was observed in seven cases in the metal-ceramic superstructure group. In all cases, dentures were removed and repaired in the laboratory. In the monolithic zirconia group, chipping was detected after one year in two cases, after two years in four cases, and after five years in one case and could be managed by polishing in situ. Monolithic zirconia superstructures presented superior results regarding the parameters evaluated.

A technical feasibility study on adaptation of a microsurgical robotic system to an intraoperative complication management in dental implantology: perforated Schneiderian membrane repair using Symani® Surgical System

The aim of the current study was to test the technical and clinical feasibility of a robotic system and investigate its potential in the surgical repair of perforated Schneiderian membranes using an ex-vivo porcine model. Eight pig heads were operated conventionally via a surgical loop and eight pig heads with the surgical robot "Symani® Surgical System" (Medical Microinstruments, Inc., Pisa, Italy). On each specimen, the Schneiderian membrane was incised over a length of 0.7 mm resembling a perforation. Operation time, the maximum sinusoidal pressure, the course of the pressure and the filling volume were measured. Additionally, adaptation of the wound edges has been detected via scanning electron microscopy. There were no significant differences for the pressure maximum (p = 0.528), for the time until the pressure maximum was reached (p = 0.528), or for the maximum filling volume (p = 0.674). The time needed for the suturing of the membrane via robotic surgery was significantly longer (p < 0.001). However, the scanning electron microscope revealed a better adaptation of the wound edges with robotic surgery. The technical feasibility of robot-assisted suturing of Schneiderian membrane laceration using the robotic system has been confirmed for the first time. No differences considering the pressure resistance compared to the conventional repair could be observed, but advantages in wound adaptation could be found with an electron microscope. Regarding the material and training costs and limited indications spectrum, robotic surgery systems still might not present financially feasible options in the daily dental practice yet.

Clinical outcomes of full-arch immediate fixed prostheses supported by two axial and two tilted implants: A retrospective cohort study with 12-15 years of follow-up

PURPOSE

To retrospectively assess clinical and radiographic outcomes of immediately loaded full-arch fixed prostheses supported by axial and tilted implants up to 15 years of function.

MATERIALS AND METHODS

Patients with one completely edentulous arch received an immediate full-arch fixed prosthesis supported by two anterior axial and two posterior tilted implants. Definitive prosthesis consisting of a CAD-CAM titanium framework and acrylic teeth was delivered 6 months later. Patients were regularly followed to assess clinical parameters and marginal bone level (MBL) change. Multilevel regression analysis was performed to investigate factors affecting implant failure and MBL.

RESULTS

Six hundred ninety-two implants were placed in 72 maxillae and 101 mandibles. Seven maxillary implants (5 axial and 2 tilted) in 6 patients and 12 mandibular implants (6 axial and 6 tilted) in 5 patients failed. 15-year cumulative implant survival was 97.51% and 96.91% in maxilla and mandible, respectively (p = .64). After 10 years, the difference in MBL between axial and tilted implants was not significant in the maxilla (p = .47, 65 patients), while it was in the mandible (p < .001, 80 patients). Significant higher bone loss was reported in the mandible at both 5- and 10-year follow-up (p < .001 and p = .004, respectively). Mixed-effect multilevel linear regression evidenced a correlation between arch and bone loss at 5- and 10-year follow-up, while no correlation was found with age, gender, smoking, diabetes, and history of periodontal disease.

CONCLUSION

This long-term study suggests that the present technique can be considered a viable treatment modality for the immediate rehabilitation of both maxilla and mandible.

Dental implant restoration for dentition defects improves clinical efficacy, masticatory function and patient comfort

OBJECTIVE

The aim of this study is to demonstrate if dental implant restoration can improve the clinical efficacy, masticatory function and comfort in patients with dentition defects.

METHODS

The clinical data of 90 patients with single tooth loss treated in Yuyao People's Hospital of Zhejiang Province from May 2018 to May 2020 were analyzed retrospectively. The patients were enrolled and divided into two groups. The control group (CG; n=45) was intervened by traditional fixed partial denture (FPD) restoration, and the observation group (OG; n=45) was treated with dental implant restoration. The clinical efficacy was evaluated, and amelioration of tooth-related indexes and clinical indicators 2 years after treatment were observed. The improvement of masticatory function and comfort scores were compared. The adverse reactions during treatment were recorded, and patients' satisfaction with the treatment was calculated. Logistic regression was performed to assess the independent risk factors for inefficacy of the treatments.

RESULTS

After treatment, the OG presented with lower gingival index, plaque index and sulcus bleeding index.

Mechanical Response of PEKK and PEEK As Frameworks for Implant-Supported Full-Arch Fixed Dental Prosthesis: 3D Finite Element Analysis

Objective  Polymeric framework represent an innovative approach for implant-supported dental prostheses. However, the mechanical response of ultra-high performance polymers as frameworks for full-arch prostheses under the “all-on-four concept” remains unclear. The present study applied finite element analysis to examine the behavior of polyetherketoneketone (PEKK) and polyetheretherketone (PEEK) prosthetic frameworks.

Materials and Methods  A three-dimensional maxillary model received four axially positioned morse-taper implants, over which a polymeric bar was simulated. The full-arch prosthesis was created from a previously reported database model, and the imported geometries were divided into a mesh composed of nodes and tetrahedral elements in the analysis software. The materials were assumed as isotropic, elastic, and homogeneous, and all contacts were considered bonded. A normal load (500 N magnitude) was applied at the occlusal surface of the first left molar after the model was fixed at the base of the cortical bone. The microstrain and von-Mises stress were selected as criteria for analysis.

Results  Similarities in the mechanical response were observed in both framework for the peri-implant tissue, as well as for stress generated in the implants (263–264 MPa) and abutments (274–273 MPa). The prosthetic screw and prosthetic base concentrated more stress with PEEK (211 and 58 MPa, respectively) than with PEKK (192 and 49 MPa), while the prosthetic framework showed the opposite behavior (59 MPa for PEEK and 67 MPa for PEKK).

Conclusion  The main differences related to the mechanical behavior of PEKK and PEEK frameworks for full-arch prostheses under the “all-on-four concept” were reflected in the prosthetic screw and the acrylic base. The superior shock absorbance of PEKK resulted in a lower stress concentration on the prosthetic screw and prosthetic base. This would clinically represent a lower fracture risk on the acrylic base and screw loosening. Conversely, lower stress concentration was observed on PEEK frameworks.