displayed the following Kennedys classification 1). A mandibular Class ... 2016, 3shape) following the basic principles of RPD components design. The software ...
EVALUATION OF 3D RPD DESIGN WITH PEEK FRAMEWORK MATERIAL -A FINITE ELEMENTS ANALYSIS STUDY. Dr. Eman Al Amodi Amodi1,, Dr. Ghaliah Alshahrani Alshahrani1,, Supervisors
Dr. Mohamed khaled Addas Addas2,, Dr. Sharaz Shaik Shaik2.. Dr. Khalid Abdulaziz 3,, Nedal Lodi 4
1Dental intern, College of dentistry, King Khalid University, Abha, Saudi Arabia. 2Assistant professor, department of prosthetic dentistry, king Khalid University College of dentistry, Abha, Saudi Arabia. 3Associate professor, department of prosthetic dentistry, king Khalid University College of dentistry, Abha, Saudi Arabia. 4Assistant professor, department of Mechanical Engineering, Al-Faisal University College of dentistry, Riyadh, Saudi Arabia.
Introduction The use of a removable partial denture (RPD) in clinical practice remains a viable and predictable treatment modality. Data on future needs for RPDs indicate that the need for RPDs is actually predicted to increase as the geriatric population increases which includes a high percentage of partially edentulous patients. [1, 2, 3]. The use of alternatives to RPD such as implants may not always be practical for a number of reasons and the benefits of RPDs are well documented [4]. CAD/CAM techniques can be used for electronic dental cast analysis, preparation, and design of RPD frameworks. It also demonstrates that RP-produced patterns may be successfully cast using conventional methods and that the resulting frameworks can provide a satisfactory fit. [5,6]. Various Options for CADCAM framework materials include cobalt chromium (Co-Cr), titanium and, more recently, poly-ether-ether-ketone (PEEK). PEEK materials have a strong history of use as implantable devices in orthopedics’ [7]. PEEK materials have recently been introduced to the dental market as nonmetal alternatives as framework materials [8, 9]. Clinical reports of the use of PEEK as a prosthodontic material in peer reviewed literature are limited [10]. The aim of this study is to present an alternative treatment approach using a PEEK framework in combination with the traditional denture base acrylic resins for the fabrication of a RPD. And to evaluate the design and stress distribution in the free end saddle removable partial dentures with framework made from poly–ether-ether ketone (PEEK) using CAD/CAM technology. A Finite element analysis study.
Fig(5): Design analysis of RPD frameworks Class II M1
Fig(7): Design analysis of RPD frameworks Class I maxilla
Preparation of the models: Casts retrieved from impressions of four different teaching models of free end saddle Kennedy classification from KKUCOD prosthodontics lab after preparation of the teeth for RPD. The four casts displayed the following Kennedys classification 1). A mandibular Class I. 2).A maxillary Class I. 3). A Maxillary Class II M 1. 4) A maxillary Class II M 2. Computer Aided Designing: The four casts were digitally scanned using 3d scanner (D-800, 3SHAPE) and the resulted files were used for framework design. The frameworks designed by using RPD prosthetic option in the CAD software (Dental system 2016, 3shape) following the basic principles of RPD components design. The software block the undercuts, after determining the suitable path of insertion and digital survey lines. Every RPD components such as clasp arms, rests, minor, major connectors, and saddle meshwork were draw. Then the preset characteristic structures of the framework, including the half-pear shaped cross section of lingual bar, and straps for the upper, the internal and external finish lines, the tissue stops at the tissue surface of mesh construction were applied. The thickness of the framework with 0.8mm have been chosen as required per (PEEK) material mechanical properties.
Fig(8): Design analysis of RPD frameworks Class II M 1maxilla
After design analysis of RPD frameworks the results were summarized in the following table Table (2): Evaluation of individual components design of RPD frameworks RPD components Class I Mandible
Materials & Methods
Fig(6) : Design analysis of RPD frameworks Class I mandible
Class I Maxilla
Class II M 1 Maxilla
Class II M 2 Maxilla
Rests
Safe Risky in the cingulum area
Safe Risky in the cingulum area
safe
safe
Major connector
SAFE
Safe Risky surface in the border
Safe Too thin in anteroposterior borders
Safe with risk and too thin surfaces in the posterior palatal seal
Risky
safe
Risk and too thin
Too thin , retentive tip risky
Safe
Safe Risky in the retentive tip
Too thin and risky
Suprabulg arm
-
-
Safe and risky in the retentive tip
Safe and risky in the retentive tip
Reciprocal arm
-
safe
Safe
Proximal Plate
safe
Risky
Risky
Risky
Risky
Risky
Risky
Minor connectors safe Retentive arm Infrabulg arm
Saddle meshwork Risky
Design analysis: The resulted files of the scanned casts and frameworks were exported to .stl file format to be used with online design analysis software (minimagic cloud, Materialise, Belgium), then corrected and modified to be compatible with the capacity of the finite elements software which uploaded with PEEK mechanical properties (ANSYS 2017, USA). The software imports the file then check the consistency of the framework for bad contours , edges and shell, in the next step the software automatically repairs the mesh if needed and reduced the triangulation of the framework, then converts the mesh to a virtual solid state for analysis after making constrains and loading forces on the entire surface of the framework. the resulted analysis appears as colored indication ranged from red to green. Red is an indication of too thin design area, yellow is indication of risk design area and green is indication of safe design area. The results were tabulated according the removable partial dentures components for design modification and mouth preparation.
Fig(9): Design analysis of RPD frameworks Class I mandible imported with Solidworks Software to be converted in a solid state
Fig(10): Finite Elements analysis of RPD frameworks Class I imported with ANSYSR _ software
Discussion
Fig(1-3): Steps of RPD framework Design
CAD/CAM technology involved in different production different prosthetic option ranging from simple comping to implant abutment suprastructure. This rapid growing may lead to confusion of the final products design and continuity to serve in patient mouth. Design analysis spot a light on different components of RPD design which have been evaluated and the result approved that the different major connector complies with form and production without error ,while the other parts need to be reconsidered in the design procedures otherwise may lead break or wear easily or may not function properly.
Results Analysis of the meshwork files revealed the following table:
Conclusion
Table (1): Results of design analysis of the RPD meshworks !
Triangles
Vertices
Facets
Class I mandible
65222
47278
94892
RPD Class I Maxilla
226714
141091
282673
RPD Class I Mod 1 Maxilla
160710
99861
200026
RPD Class II Mod 2 Maxilla
259146
142013
284332
The triangles have been reduced to a nonsignificant numbers that not affects the design of the frameworks as: Class I maxilla reduced by 504 triangles, Class II M1 maxilla reduced by 424 triangles.
Fig(4): Distribution of different meshwork elements of different RPD classes after scanning
Within the limitation of this study, the design analysis suggests that the PEEK framework will be better functioning if its thickness is more than 0.8 mm for certain components of removable partial dentures. Design analysis provide a convenient method for RPD design and preserve safe time and material and reduce failure rate of RPD.
References
Jones, John D 1 ; Turkyilmaz, Ilser; Garcia, Lily T; Removable partial dentures--treatment now and for the future. Texas dental journal 2010 Apr;127(4):365-72. STEELE, J. G., TREASURE, E. T., O'SULLIVAN, I., MORRIS, J. & MURRAY, J. J. 2012. Adult Dental Health Survey 2009: transformations in British oral health 1968-2009. Br Dent J, 213, 523-7. Anderson GF, Hussey PS: Population aging: a comparison among industrialized countries, Health Affairs 19:191-203, 2000. MCCORD, J. F., GREY, N. J., WINSTANLEY, R. B. & JOHNSON, A. 2002a. A clinical overview of removable prostheses: 1. Factors to consider in planning a removable partial denture. Dent Update, 29, 376-8 M. Bilgin, E. Baytaroglu, A. Erdem, and E. Dilber, “A review of computer-aided design/computer-aided manufacture techniques for removable denture fabrication,” European Journal of Dentistry, vol. 10, no. 2, pp. 286–291, 2016. Eggbeer, D 1 ; Bibb, R; Williams, R 1 The computer-aided design and rapid prototyping fabrication of removable partial denture frameworks. Proceedings of the Institution of Mechanical Engineers. Part H, Journal of engineering in medicine 3 —KURTZ, S. M. & DEVINE, J. N. 2007. PEEK biomaterials in trauma, orthopedic, and spinal implants. Biomaterials, 28, 4845-69. 4 — SANTING, H. J., MEIJER, H. J., RAGHOEBAR, G. M. & OZCAN, M. 2012. Fracture strength and failure mode of maxillary implant-supported provisional single crowns: a comparison of composite resin crowns fabricated directly over PEEK abutments and solid titanium abutments. Clin Implant Dent Relat Res, 14, 882-9. 5 — STAWARCZYK, B., BEUER, F., WIMMER, T., JAHN, D., SENER, B., ROOS, M. & SCHMIDLIN, P. R. 2013. Polyetheretherketone-a suitable material for fixed dental prostheses? J Biomed Mater Res B Appl Biomater, 101, 1209-16. 6 –- COSTA-PALAU, S., TORRENTS-NICOLAS, J., BRUFAU-DE BARBERA, M. & CABRATOSA-TERMES, J. 2014. Use of polyetheretherketone in the fabrication of a maxillary obturator prosthesis: A clinical report. J Prosthet Dent
