Individual Lithium Disilicate Crowns in a Full-Arch, Implant-Supported Rehabilitation: A Clinical Report

Evaluation of Stresses on Implant, Bone, and Restorative Materials Caused by Different Opposing Arch Materials in Hybrid Prosthetic Restorations Using the All-on-4 Technique

The long-term success of dental implants is greatly influenced by the use of appropriate materials while applying the “All-on-4” concept in the edentulous jaw. This study aims to evaluate the stress distribution in the “All-on-4” prosthesis across different material combinations using three-dimensional finite element analysis (FEA) and to evaluate which opposing arch material has destructive effects on which prosthetic material while offering certain recommendations to clinicians accordingly. Acrylic and ceramic-based hybrid prosthesis have been modelled on a rehabilitated maxilla using the “All-on-4” protocol. Using different materials and different supports in the opposing arch (natural tooth, and implant/ceramic, and acrylic), a multi-vectorial load has been applied. To measure stresses in bone, maximum and minimum principal stress values were calculated, while Von Mises stress values were obtained for prosthetic materials. Within a single group, the use of an acrylic implant-supported prosthesis as an antagonist to a full arch implant-supported prosthesis yielded lower maximum (Pmax) and minimum (Pmin) principal stresses in cortical bone. Between different groups, maxillary prosthesis with polyetheretherketone as framework material showed the lowest stress values among other maxillary prostheses. The use of rigid materials with higher moduli of elasticity may transfer higher stresses to the peri implant bone. Thus, the use of more flexible materials such as acrylic and polyetheretherketone could result in lower stresses, especially upon atrophic bones.

Bond strength of lithium disilicate to polyetheretherketone

STATEMENT OF PROBLEM

Polyetheretherketone (PEEK) is a high-performance polymer that is increasingly used in dentistry, for example, as a framework for implant-supported fixed complete dentures. One protocol calls for individual lithium disilicate crowns to be cemented on preparation-shaped retentive elements on the framework. However, the flexibility and strength of the bonded system is unclear.

PURPOSE

The purpose of this in vitro study was to compare the flexibility and strength of bonded lithium disilicate to PEEK with the bond between lithium disilicate and zirconia.

MATERIAL AND METHODS

Fifteen PEEK (JUVORA Dental Disc), 15 zirconia (ArgenZ HT+), and 30 lithium disilicate (IPS e.max CAD) beam-shaped specimens (12.5×2×2 mm) were prepared. The ends of the PEEK beams were conditioned with 50-μm aluminum oxide airborne-particle abrasion, followed by primer (visio.link) and light-activated polymerization. Zirconia specimens were prepared with airborne-particle abrasion and primer (Monobond Plus). Lithium disilicate specimens were etched with 4.5% hydrofluoric acid (IPS Ceramic Etching Gel) and primed (Monobond Plus). The lithium disilicate specimens were cemented (Multilink Automix) to the PEEK and zirconia specimens. Light- and chemical-activated polymerization were used. Monolithic specimens of PEEK and zirconia (25×2×2 mm) were also prepared. All specimens were stored overnight in distilled water and submitted to a 4-point bend test in a universal testing machine at 0.5 mm/min crosshead speed until fracture, and the flexural modulus and strength were calculated. Differences among groups were statistically tested by using 1-way analysis of variance followed by the Student-Newman-Keuls post hoc test (α=.05).

RESULTS

All bonded specimens fractured at their adhesive interface. Zirconia bonded to lithium disilicate specimens (29.7 ±8.8 MPa) were approximately 3 times stronger than PEEK bonded to lithium disilicate specimens (10.4 ±2.7 MPa) and approximately 12 times more rigid (78.5 ±6.7 GPa and 6.5 ±1.8 GPa, respectively). The flexure of monolithic PEEK was such that it did not fracture when loaded at 0.5 mm/min, while zirconia fractured at 413.9 ±38.5 MPa. Monolithic PEEK was approximately 37 times more flexible than monolithic zirconia (4.3 ±0.3 GPa and 157.2 ±7.2 GPa, respectively). All values were statistically significantly different except between the flexural moduli of monolithic PEEK and PEEK bonded to lithium disilicate.

CONCLUSIONS

The bond strength between PEEK and lithium disilicate was significantly weaker than between zirconia and lithium disilicate. Monolithic zirconia was significantly stiffer than monolithic PEEK.

Three-dimensional–printed malo bridge: Digital Fixed prosthesis for the partially edentulous maxilla

Screw-retained implant restorations have an advantage of predictable retention, retrievability, and lack of potentially retained subgingival cement. However, a few disadvantages exist such as need for precise placement of the implant for optimal and esthetic location of the screw access hole and obtaining passive fit. Malo bridge with customization of abutment can establish a precise patient's gingival architecture. It is the most esthetically advanced form of fixed prosthodontic rehabilitation for complete and partially edentulous patients. This prosthesis is combined with three-dimensional (3D)–printed computer-aided design and computer-aided manufacturing technology to gain the precise fit and added esthetics. It also has advantages such as elimination of screw access openings, makes it possible to remove and repair the fractured porcelain of the individual crown without removing the whole structure, excellent precision, avoids casting errors, light weight, reduced complexity of laboratory procedures, high definition of morphology, and time-consuming. This case report presents replacement of partially edentulous maxilla using 3D-printed Malo bridge.

Patient-Reported and Clinical Outcomes of Implant-Supported Fixed Complete Dental Prostheses: A Comparison of Metal-Acrylic, Milled Zirconia, and Retrievable Crown Prostheses

The purpose of this retrospective study was to assess the incidence of biologic and technical complications for implant-supported fixed complete dental prostheses (IFCDPs) and their relationship to oral health-related quality of life (OHQoL) and patient-reported outcomes. Metal-acrylic (MA), retrievable crown (RC), monolithic zirconia (MZ), and porcelain veneered zirconia (PVZ) prostheses were included. Patients who received an IFCDP at least 1 year prior to recall were identified. Exclusion criteria were: (1) an opposing complete denture and (2) time in service >70 months. A total of 37 patients with 49 prostheses, including 22 MA, 14 RC, 7 MZ, and 6 PVZ prostheses were recalled. Patient-reported outcomes were assessed via OHIP-49 (Oral Health Impact Profile) and a scripted interview with open-ended questions. All designs had high complication rates (12 of 22 MA, 10 of 14 RC, 2 of 7 MZ, and 5 of 6 PVZ). The most common complications were: (1) MA: posterior tooth wear, (2) RC: chipping and fracturing of the restorations, (3) MZ: wear of opposing restorations, and (4) PVZ: chipping of opposing restorations. Average OHIP-49 scores ranged from 7 to 29, indicating high OHQoL, patient satisfaction, regardless of prosthetic design (P = .16). The standardized interview highlighted that although most patients were extremely satisfied (73%), some continued to be bothered by material bulk (14%) and felt that maintenance of oral hygiene was excessively time-consuming (16%). In the context of this study, despite high complication rates and maintenance needs, all IFCDP designs resulted in high OHQoL and patient satisfaction.

Influence of transmucosal height in abutments of single and multiple implant-supported prostheses: a non-linear three-dimensional finite element analysis

The aim of this study was to analyze the influence of three different transmucosal heights of the abutments in single and multiple implant-supported prostheses through the finite element method. External hexagon implants, MicroUnit, and EsthetiCone abutments were scanned and placed in an edentulous maxillary model obtained from a tomography database. The simulations were divided into two groups: (1) one implant with 3.75 × 10 mm placed in the upper central incisor, simulating a single implant-supported fixed prosthesis with an EsthetiCone abutment; and (2) two implants with 3.75 × 10 mm placed in the upper lateral incisors with MicroUnit abutments, simulating a multiple implant-supported prosthesis. Subsequently, each group was subdivided into three models according to the transmucosal height (1, 2, and 3 mm). A static oblique load at an angle of 45 degrees to the long axis of the implant in palatal-buccal direction of 150 and 75 N was applied for multiple and single implant-supported prosthesis, respectively. The implants and abutments were assessed according to the equivalent Von Mises stress analyses while the bone and ceramics were analyzed through maximum and minimum principal stresses. The total deformation values increased in all models, while the transmucosal height was augmented. The transmucosal height of the abutments influences the stress values at the bone, ceramics, implants, and abutments of both the single and multiple implant-supported prostheses, with the transmucosal height of 1 mm showing the lowest stress values.

Full mouth rehabilitation with retrievable metal-ceramic implant-supported fixed prostheses for a young patient with atrophic jaws: a clinical report

Treatment of atrophic edentulous jaws with implant‐supported fixed prostheses is one of the most complicated challenges in dentistry. This clinical report describes the prosthesis which consists of screw retained frameworks with individual cement retained crowns which combines the advantages of the screw retained restoration with the advantage of cement retained.