2023 ACP ANNUAL SESSION

An In Vitro Comparison of Work of Fracture Load in One-Piece Milled, Two-Piece Milled,
and Conventionally Processed Complete Dentures
Jamie Progebin DMD, Kankshinee Shah BDS, DDS, Malvin Janal PhD, Mijin Choi DDS, MS, MBA, FACP

Jonathan and Maxine Ferencz Advanced Education Program in Prosthodontics New York University College of Dentistry

Introduction

Over 36 million Americans are completely edentulous.1 Even with implant technology, complete dentures remain the most common prosthesis offered to patients in the world.2,3 Despite material improvements, denture base fractures still occur.3,4,5,6 CAD/CAM makes denture fabrication more efficient.7,8 While additive technology appears promising, improvements are needed before use as definitive prostheses and limitations include esthetics, retention, occlusion, and printer resolution.2 Studies show 3D printed CDs are weaker compared with milled or conventionally processed CDs.9 Subtractive manufacturing studies show that milled CDs have superior flexural strength and offer other improved mechanical properties compared to conventionally processed CDs.10,11,12,13 Recently, Ivoclar® (Schann, Liechtenstein) released a one-piece millable disc, which includes the base and the denture teeth. There are claims that one-piece products are stronger compared to two-piece systems. But due to the recent release, independent comparative studies are lacking.

Objectives

Prior research studies investigated the flexural strength of milled complete dentures (CDs), revealing superior results to conventional and 3-D printed CDs. However, studies comparing two-piece milled and bonded CDs with one-piece milled CDs remain sparse. This study aims to evaluate fracture load of different denture materials and compare the work of fracture load of IvoBase® High Impact (conventionally processed), IvoBase® CAD (two-piece milled), and Ivotion ® (one-piece milled) CDs.

Methods

A laboratory desktop scanner was used to scan a mandibular edentulous cast. Subsequently, a complete denture was designed and fabricated using varying materials, with twelve samples per group. Group 1 utilized an IvoBase ® High Impact (injection molding) with Ivoclar Blue Line ® denture teeth. Group 2 used an IvoBase® CAD disc and denture teeth bonded with Ivoclar bonding agent. Group 3 Ivotion® disc (Fig. 1). The dentures were artificially aged, mounted, and loaded at a rate of 1 mm per minute on a universal testing machine (Fig. 2). The maximum fracture load (N) was recorded, and the work of fracture load (kJ) was then calculated.

Results

The mean fracture loads recorded for the IvoBase ® High Impact, IvoBase ® CAD, and Ivotion ® groups were 290.83 N, 246 N, 485.42 N respectively. The mean work of fracture loads for the IvoBase ® High Impact, IvoBase ® CAD, and Ivotion ® groups were 1.82 kJ, 1.58 kJ, 3.22 kJ respectively (Table 1, Fig 3). A One-way ANOVA and Tukey test revealed a statistically significant difference between the Ivotion ® group and the other two groups (P<0.05). There was no significant differences found between the IvoBase ® CAD and the IvoBase ® High Impact groups.

Conclusion

Within limitations of this study, it can be concluded that the Ivotion ® CD group had the highest fracture load and work of fracture load, which was statistically significant compared to the IvoBase ® High Impact and IvoBase ® CAD groups.

References

CentersforDiseaseControlandPrevention.(2021,December9).Edentulismandtoothretention.Centersfor Disease. Control and Prevention.
Anadioti,E,etal.3DPrintedCompleteRemovableDentalProstheses:ANarrativeReview.BMCOralHealth 2020;20.
Srinivasan,Metal.CAD/CAMmilledremovablecompletedentures:timeandcostestimationstudy.JDent 2019;80:75-9.
EttingerRL,QianF.Longitudinalassessmentofdenturemaintenanceneedsinanoverdenturepopulation.J Prosthodont 2019;28:22-9.
DarbarUR,HuggettR,HarrisonA.Denturefracture--asurvey.BrDentJ1994;176:342-55.
HargreavesAS.Theprevalenceoffractureddentures.Asurvey.BrDentJ1969;126:451–55.
Choudhary,S.Completedenturefracture-AproposedclassificationsystemanditsincidenceinNationalCapital

Region population: A survey. J Indian Prosthodont Soc 2019;19:307-12.
Kalberer,N,etal.CAD-CamMilledversusRapidlyPrototyped(3D-Printed)CompleteDentures:AninVitro

Evaluation of Trueness. J Prosthet Dent 2019;121:637-43.
Ulmer,M.Biocompatibilityandmechanical/physicalpropertiesof3Dprinted,milled,andconventionally

processed denture base materials. Diss. Augusta University, 2019.
Arslan M, Murat S, Alp G, et al. Evaluation of flexural strength and surface properties of prepolymerized

CAD/CAM PMMA-based polymers used for digital 3D complete dentures. Int J Comput Dent 2018;21:31-40.

11.Al-Dwairi ZN, Tahboub KY, Baba NZ, et al. A comparison of the flexural and impact strengths and flexural

modulus of CAD/CAM and conventional heat-cured polymathy methacrylate (PMMA). J Prosthodont

2018;29:341-49.
12. Prpić, V, et al. Comparison of Mechanical Properties of 3d-Printed, CAD/CAM, and Conventional Denture Base

Materials. J Prosthodont 2020;29:524-28.
13. Srinivasan, M, et al. CAD-Cam Removable Complete Dentures: A Systematic Review and Meta-Analysis of

Trueness of Fit, Biocompatibility, Mechanical Properties, Surface Characteristics, Color Stability, Time-Cost Analysis, Clinical and Patient-Reported Outcomes. J Dent 2021;113:103.

Research Support

• Greater New York Academy of Prosthodontics Student Grant • Ivoclar ®

2023 ACP ANNUAL SESSION

An In Vitro Comparison of Fracture Load in One-Piece Milled, Two-Piece Milled, and Conventionally Processed Complete Dentures

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