Evaluation of Stresses Induced by OT Bridge Prosthetic System with Different Number of Scews in All on Six Maxillary Prosthesis (In Vitro Study)

doi:10.21203/rs.3.pex-2549/v1

Method Article

Evaluation of Stresses Induced by OT Bridge Prosthetic System with Different Number of Scews in All on Six Maxillary Prosthesis (In Vitro Study)

https://doi.org/10.21203/rs.3.pex-2549/v1

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The hazardous stresses that could be induced by missing or broken screws in full-arch implant prostheses and the occasional esthetic need for eliminating screws mandate selecting stable prosthetic systems even with a lack of full screw connection. Using finite element analysis this study aims to evaluate the stresses induced by the OT-bridge system (Rhein83®) in the absence of an entire screw anchorage. After exporting the geometry information of; a CAD/CAM prototype of an edentulous maxilla with six implants, and its framework that will be simulated using OT bridge system “extragrade” abutments to the meshing software, boundary and loading conditions will be set and the analysis will be run under axial load 250 N and non- axial load 150 N at 30° inclination. The average Von Mises stress, and displacement values will be calculated for a number of 43 components of five test groups categorized according to the number and distribution of the applied screws. Data obtained from comparing the groups will be used to determine what is the maximum number of screws that could be eliminated without affecting the prosthetic stability or inducing hazardous stresses.

Implant rehabilitation

Fully edentulous maxilla

Finite element analysis

OT bridge system

screw-retained prosthesis

Prosthesis stability.

The advent of dental implant-based therapies quickly developed as a safe and predictable remedy for fully edentulous patients and as an alternative to standard removable dentures.In the past 20 years, many treatments have included prosthodontic rehabilitation involving high or low numbers of dental implants, cemented or screw-retained fixed dental prostheses, and dental implant-supported overdentures. ⁽¹⁾The choice of reliable and predictable implant-prosthetic systems is essential in dental clinical practice, as well as in improving the quality of life from both a functional and aesthetical point of view.The prosthodontist’s job is to study the appropriate prosthetic project evaluating benefits, costs, and the expectations of the patient.⁽²⁾

In recent years, much dental research has focused heavily on the problem of prosthetic failure. The most common complications are related to the lack of prosthetic space or bad prosthetic design, along with aesthetic, phonetic, and maintenance problems.⁽³⁾Another concern is the high-tension concentrations at the bone-implant interface which can activate peri-implant bone loss followed by implant failure.⁽⁴⁾ This highlighted how knowledge and analysis of the stresses produced by the implant prosthetics become necessary.⁽⁵⁾ The knowledge of the distribution of tensions and deformations in maxillary bones and implants is of fundamental importance for the evaluation of osseointegration and adequate stability of the implant itself. A significant contribution to the prosthesis failure studies is given by finite element analysis (FEA) which simulates the real behavior of the components under predefined load conditions. ⁽⁶⁾

The use of the multiunit abutment system is the best choice for producing screw-retained implant-supported prostheses. The multiunit abutments enable passive adjustment of the prosthesis, even if implants are not parallel. In addition, the intraoperative placement of multiunit abutments protects the peri-implant soft tissue from damage caused by multiple screwing and unscrewing of implant superstructures, as all manipulations occur above the bone level and the implant platform. ⁽⁷⁾ On the other hand, the biggest disadvantage of this particular abutment is that the screw that holds the bridge on is quite tiny, so tightening the screw down can be difficult. ⁽⁸⁾The multi-unit abutment is shaped like a cone, if one cone is in alignment with another cone a bridge made over it will not rock from side to side, we call this passive fitting of the prosthetic bridge, however, if there is no alignment between the multi-unit abutments, passive seating of the restoration will be compromised, additional fabricated caps may be needed for achieving better parallelism, with additional financial concerns for dentist and patients. ⁽⁹⁾

The OT-bridge system (Rhein83®) was introduced as an original solution to many of the limitations of other fixed prosthetic systems in the market thanks to its various components that make it unique; This system is based on the use of the low-profile OT Equator attachment, the sub-equatorial component"Seeger" which is an interchangeable acetal ring housed in a cylindrical “Extra grade” abutment is one of the basic elements of this product and represents a systematic alternative to the screwed and cemented dentures. ⁽¹⁰⁾ The Seeger system could allow the elimination of many holes for the connection screws due to the retentive force of the acetal ring. The clinician will be able to use the abutments in "blind mode" without any connection screw, keeping the connection only to the Seeger. Thus, it is possible to realize a fixed full-arch prosthesis by avoiding unaesthetic holes for the connection screws.⁽¹¹⁾Usually, 1 to 2 screws can be avoided in the case of 4 to 6 placed implants respectively. In fact, in a recent publication on fixed complete arches restorations, 3 out of 76 implants were connected to the prosthetic framework using only the Seeger system without a screw when the OT Bridge system (Rhein83®) was used.⁽¹²⁾ In this regard, it is important to define a correct assembly criterion in concern to the possible number and distribution of abutments that could be used without screws together with achieving adequate stability of the OT bridge prosthesis. ⁽¹³⁾Thus, the present study will be conducted to assess and compare the generated stresses and the prosthesis stability between different OT bridge prosthetic configurations that differ in the number and distribution of employed retaining screws.

Rhein OT bridge catalog: available from; MOD.D3933SP REV.02. Del 11/09/2023

ABAQUS/Standard Explicit model.

Fusion 360 modeling software.

This study will comprise five test groups based on the number and geometrical distribution of the connection screws that will be used to anchor the screw-retained all-on-six implant framework, as follows:

Group A: Six connection screws will be applied to secure the OT bridge prosthetic framework to the six implants.

Group B: Five connection screws will be applied to secure the OT bridge prosthetic framework to the implants, entrusting the connection only to the Seeger for one implant.

Group C: Four connection screws will be applied to secure the OT bridge prosthetic framework to the implants, entrusting the connection only to the Seeger for two anterior implants unilaterally.

Group D: Four connection screws will be applied to secure the OT bridge prosthetic framework to the implants, entrusting the connection only to the Seeger for two anterior implants bilaterally.

Group E: Three connection screws will be applied to secure the OT bridge prosthetic framework to the implants, entrusting the connection only to the Seeger for three anterior implants.

a) Experimental design modeling

A 3D model of an edentulous maxilla that could be restored with a full arch fixed implant prosthesis will be simulated. Following the Carl Mesh approach “All‑on‑six” design: two anterior implants will be placed at the central incisors’ region, two implants will be placed at the canines’ regions, while the most posterior implants will be placed at the first molars’ regions. After scanning, implants will be replicated along with their corresponding equator abutments using 3D modeling software. The framework will be designed as an anatomic setup based on the virtual prosthetic teeth arrangement (12 teeth from central incisors to first molars bilaterally). Based on the public digital library available for the OT-Bridge prosthetic system (Rhein83®), the connection of the prosthetic framework will be modeled, and the Seeger rings will be simulated inside the extragrade abutments as specified by the manufacturer.

b) System setup

- After the creation of the 3D model, the specialized engineer will perform FEM of a schematized elaborate; bone will be schematized as cylindrical volumes and several 43 components will be tested, for each part of the assembly markers will be attributed, and the identification numbers will be as follow: abutments (1-6), screws (7-12), bridge (13), cortical bone cylinders (14-19), fixtures (20-25), cancellous bone cylinders (26-31), Seeger rings (32-37), equators (38-43). This will allow analysis and comparison of five different OT Bridge prosthesis system approaches for the rehabilitation of a completely edentulous maxilla. All systems will employ six implants, the difference between the five prostheses system configurations consisted in the number and distribution of connection screws applied.

c) FEM analysis

- Solid elements will be used to represent the geometry. All the 3D models of the implants and framework will be built using Solid Edge software. Bone will be built by a reverse engineering processor. Meshwork will be prepared using Hyper Mesh software. The analysis will be done by ABACOS software. The mechanical characteristics that will be used for the simulations (cortical bone, cancellous bone, prosthesis, abutments, and Seeger) will be obtained from similar previous studies ^{(14, 15)}. Boundary and loading conditions will be set. - An axial load of 250 N will be applied at the premolar-molar region bilaterally. A nonaxial load of 150 N will be applied at an angle at the same site with a 30° inclination in the linguo-buccal direction. The use of ABAQUS Workbench will allow analyzing the whole system set up in each of the five test groups for evaluation of the following:

· Stress amount and distribution

The software will give quantitative values at different locations for each part of the assembly. The software will also assess compressive and tensile strain along with von Mises stress.

· Micromotion/displacement

The focal point of this research is to evaluate the stability of the prosthesis so that the software will analyze total displacement and the displacements along every single axis. The relative displacement between two nodes of elements on the framework-abutment interface is equivalent to micromotion.

Data analysis

The average Von Mises stress will be calculated for the components of all tests, and displacement values will be recorded. Data will be transferred into digital format. The obtained data will be recorded, tabulated, and statistically analyzed using the appropriate statistical tests for comparing the four groups to be tested.

Step during modeling

problem Creation of a suitable file format to export geometry data to the meshing software.

Possible reason Compatibility issues

solution Use Fusion 360 modeling software to create a STEP file to export to ABAQUS as a solid body.

Step during meshing

problem Low-quality mesh in the bridge.

Possible reason The shape of the bridge is complicated.

solution Simplify the bridge shape by combining some faces and using tetrahedral elements to ensure a high mesh quality.

Step during analysis

problem Elongated run time.

Possible reasonDecreased size of elements of the bridge.

solution Decrease the size of elements only in areas of interest

four months

We expect that failure to anchor the prosthesis with the entire number of connection screws will have no impact on the stability and stress distribution in the system.

1. Montanari M., Bonato G., and Ortensi L., 2016. Oral rehabilitation with implant-supported overdenture and a new protocol for bar passivation. Global J. Oral ScAi, 2: 10–19.

2. Tallarico M., Caneva M., Baldini N.,Gatti F., Duvina M., Billi M., Iannello.G, Piacentini G., 2018. Patient-centered rehabilitation of single, partial, and complete edentulism with cemented- or screw-retained fixed dental prosthesis: the first osstem advanced dental implant research and education center consensus conference 2017. Eur. J. Dent., 12(4):617–626.

3. Zitzmann N.U., Margolin M.D., Filippi A., Weiger R., Krastl G., 2008. Patient assessment and diagnosis in implant treatment. Aust. Dent. J., 53: 3-10.

4. Romeo E., Chiapasco M., Ghisolfi M., Vogel G., 2002. Long-term clinical effectiveness of oral implants in the treatment of partial edentulism: Seven-year life table analysis of a prospective study with ITI® Dental Implants System used for single-tooth restorations. Clin. Oral Implants Res, 13:133–143.

5. Milone D., Nicita F., Cervino G., Santonocito D, 2021. Finite element analysis of OT Bridge fixed prosthesis system: 26th international conference on fracture and structural integrity. J. Prosthodont. 33: 734-747.

6. Cervino G., Cicciù M., Fedi S., Milone D, Fiorillo L., 2020. FEM Analysis applied to OT bridge abutment with seeger retention system. Eur. J. Dent., 8: 5.

7. Igor A., Artem T., Svetlana T., Sabina M., Svetlana T., 2020. Case Report Full-Mouth Screw-Retained Implant Supported Rehabilitation with Multiunit Abutments Using Virtual Guided Surgery and Digital Prosthetics Protocol. Case Reports in Dentistry, ID 3585169. doi: 10.1155/2020/3585169.

8. Tonetti MS., Hämmerle CHF., 2008. Advances in bone augmentation to enable dental implant placement. J. Clin. Periodotal. 35 (8 suppl), 168-172

9. Cervino G., Montanari M., Santonocito D.,Nicita F., Baldari R., De AngelisC., Storni G, Fiorillo L.; 2019. Comparison of two low-profile prosthetic system interfaces: Preliminary Data of an In Vitro Study. Prosthesis. 1(1), 54-60.

10.Acampora R., Montanari M., Scrascia R.,Ferrari E., Pasi M., Cervino G., Meloni S.M., Lumbau A.I, Xhanari E., Koshovari A., Tallarico M., 2021. 1-Year evaluation of OT bridge abutments for immediately loaded maxillary fixed restorations: a multicenter study. Eur. J. Dent., 15:290–294

11.Milone D., Nicita F., Cervino G., Santonocito D, 2021. Finite element analysis of OT Bridge fixed prosthesis system: 26th international conference on fracture and structural integrity. J. prosthdont, 33: 734-747.

12.Montanari M., Scrascia R., Cervino G., Pasi M., Ferrari E., Xhanari E., Koshovari A., Tallarico M, 2020. A one-year, multicenter, retrospective evaluation of narrow and low-profile abutments used to rehabilitate complete edentulous lower arches: the OT bridge concept. J. Prosthodont, 2: 352–361.

13.Tallarico M., Canullo L., Caneva M., Özcan M., 2017. Microbial colonization at the implant- abutment interface and its possible influence on peri-implantitis: a systematic review and meta-analysis. J. Prosthodont, 61(3): 233–241.

14.Chung T., Ganeshkar S.V., Revankar A.V., Jain AK., 2013.Quantitative assessment of interradicular bone density in the maxilla and mandible: implications in clinical orthodontics.Progress in orthodontics, 14:38.

15. Lemos C.A.A., Verri F.R., Junior J.F.S., Batista V.E.S., Kemmoku D.T., Noritomi P.Y., Pellizzer E.P.,2018. Splinted and Nonsplinted Crowns with Different Implant Lengths in the Posterior Maxilla by Three-Dimensional Finite Element Analysis. Volume 2018, Article ID 3163096, 7 pages.

- Abdelrhman Alaa Ali Nosair; DigitaLVitronex Company, Egypt, B.D.S 2018, faculty of dentistry, Sinai University. For creating of virtual model with digital analog and bridge, and Stl file remesh to be suitable for Finite Element Analysis (FEA).

- Abdulrhman Atef: Assistant lecturer, Mechanical Engineering Department, the British University in Egypt. For creating a Finite Element Analysis (FEA) model comparing stress values by applying the same loading conditions, finally running the analysis based on the given loading conditions.

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Evaluation of Stresses Induced by OT Bridge Prosthetic System with Different Number of Scews in All on Six Maxillary Prosthesis (In Vitro Study)

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Evaluation of Stresses Induced by OT Bridge Prosthetic System with Different Number of Scews in All on Six Maxillary Prosthesis (In Vitro Study)

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Anticipated Results

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