In vitro fatigue resistance of CAD/CAM composite resin and ceramic posterior occlusal veneers – Biomimetic Dentistry Literature Review

AUTHORS: Pascal Magne, DMD, PhD, Luís Henrique Schlichting, DDS, MS, Hamilton Pires Maia, DDS, PhD, and Luiz Narciso Baratieri, DDS, PhDd
YEAR: 2010
JOURNAL: The Journal of Prosthetic Dentistry

The purpose of this study was to assess and compare the fatigue resistance of composite resin and ceramic posterior occlusal veneers. Occlusal veneers are thin, bonded, posterior restorations used as a conservative alternative to traditional complete coverage crowns.

Partial coverage restorations remove half the amount of tooth structure compared to complete coverage metal ceramic crowns. With survival rates of 88.7% after 17 years and 84% after 12 years, porcelain adhesive inlays and onlays have demonstrated long-term reliability.
Occlusal veneers are extracoronal restorations requiring a simpler and more intuitive preparation driven by interocclusal clearance and anatomical considerations. The usual recommendation for porcelain restoration thickness is 1.5 to 2.0 mm. However, given the development of stronger materials in combination with CAD/CAM techniques AND innovative adhesive technology such as immediate dentin sealing, more conservative approaches are explored as potential treatment options.

The restorations were designed with an average thickness of 1.2 mm at the central groove, a maximum of 1.8 mm at the cusp tip, and 1.6 mm at the internal cusp slope. The materials tested include reinforced glass ceramics (IPS Empress CAD; Ivoclar Vivadent; group ECAD), lithium disilicate (IPS e.max; Ivoclar Vivadent; group EMAX), and composite resin (Paradigm MZ100 blocks; 3M ESPE; group MZ100).

Biomimetic Dentistry - Occlusal Veneer

Cyclic load (isometric mastication using load control) was applied at a frequency of 5 Hz, starting with a load of 200 N for 5000 cycles, followed by stages of 400, 600, 800, 1000, 1200,and 1400 N at a maximum of 30,000 cycles each. To meet the criteria for “failure,” a specimen had to exhibit 1 or more surface cracks greater than or equal to 2 mm in length.

Results

  • There were no catastrophic failures with loss of a restoration fragment.
  • None of the specimens experienced loss of or significant damage to intact tooth structure (Biomimetic Restoration!)
  • Composite resin MZ100 had a significantly increased fatigue resistance.

occlusal Veneer Chart


Biomimetic Dentistry CE:

This study utilized immediate dentin sealing (IDS), a technique fundamental to Biomimetic Dentistry, with all specimens. Despite the high loads used in the study and the “mosaiclike” cracking observed, none of the fractured fragments separated from the tooth, which demonstrated the fatigue resistance of the dentin bond achieved with IDS. Cracks were restricted to the restorations and remaining enamel in all tested groups. This demonstrates the “biomimetic” behavior of the restoration and underlying tissue, simulating to some degree the enamel cracks stopped at the dento-enamel junction (DEJ) which we also refer to as the Dentino-Enamel Complex because it is a complex interPHASE rather than a simplified interFACE.

The uniaxial flexural strength of ceramic blocks (256 and 127 MPa for EMAX andECAD, respectively) compared to that of the composite resin blocks (150 MPa for MZ100) did not correlate with their respective survival rates in this study. This brings up another key principle which a Biomimetic Dentist must understand: structural integrity of complex structures made from multilayered materials, such as restored teeth, cannot be predicted using strength data alone.

With Biomimetic Bond strengths, conventional material selections and preparation principles are not necessarily required. The maximum bond strengths achieved through immediate dentin sealing and luting protocols allow for novel designs for preparations as well as new material selection possibilities.


How many of you have been having good results with immediate dentin sealing and thinner restorations? Anyone using mz100 restorations? Comment or leave a question.


Matt Nejad About Matt Nejad

Dr. Nejad graduated from the University of Southern California School of Dentistry with recognition for a record setting amount of fixed prosthodontic procedures completed. He was the youngest dentist to become a clinical instructor at USC, at the age of 26, and he has given lectures on Morphology and Occlusion (since 2010). He is a premiere educator in Biomimetic Dentistry, presenting at numerous conferences by invitation and providing continuing education courses for dentists. He also has private practices in Simi Valley, CA and Beverly Hills, CA.

He has been teaching dentists from around the world, how to improve their adhesive dentistry and provide conservative restorations with the biomimetic approach.

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