Marginal gap and fracture resistance of CAD/CAM ceramill COMP and cerasmart endocrowns for restoring endodontically treated molars bonded with two adhesive protocols: an in vitro study

Figures & data

Table 1. Chemical compositions, manufacturers, and product names of the various materials used in this study.

Product name	Type	Composition	Modulus of elasticity	Manufacturer
Cerasmart	Flexible resin nanoceramic blocks	Flexible nano ceramic matrix with an even distribution of nanoceramic	12.1 MPa	GC America, Inc
Ceramill COMP	Ceramic based composite	Strontium boroaluminosilicate glass 78 % nanofillers, BODMA, Bis-GMA, UDMA. Ceramill COMP corresponds to Creamed AMBARINO High-class blanks	13.8 MPa	Amann Girrbach, Germany
RelyX Ulitmate	Dual cure resin cement	Methacrylate monomers, radiopaque, silanated fillers, radiopaque alkaline (basic) fillers, initiator components, stabilizers, rheological additives, pigments and dark cure activator for Scotchbond universal adhesive	7.7 GPa	3M ESPE, Germany

Figure 1. Proximal view of the virtual model for endocrown restoration.

Figure 2. Cross sectional view of virtual model for endocrown restoration.

Figure 3. Ceramill COMP steromicroscope (90X magnification) A: before aging; B: after aging.

Figure 4. Cerasmart steromicroscope (90X magnification) A: before aging; B: after aging.

Figure 5. Mean marginal gap before and after thermo-mechanical aging via different bonding protocols for each material approach.

Table 2. Comparisons of the marginal gaps for the different material groups and bonding protocols.

	Total-etch				Self-etch
Variables	Mean	Ceramill COMP	Cerasmart	p-Value	Mean	Ceramill COMP	Cerasmart	p-Value
Before
Mean	46.6	45.4	47.7	0.3	48.2	47.9	48.4	.7
SD	6.4	5.7	6.9		7.1	6.6	7.8
After
Mean	43.4	40.8	45.9	.002***	45.7	45.4	46.1	.06
SD	5.5	6.1	3.2		4.6	5.7	3.2
p-Value	.004*	.002**	0.3		.04*^a	0.2	0.08

*Significant difference between the two bonding protocols. **Significant difference between each bonding protocol before and after aging for each material approach. ***Significant difference between the two endocrown materials.

Figure 6. Mean load required to fracture.

Table 3. Comparisons of the load required to fracture the endocrown with respect to the material used and different bonding protocols.

Variables	Mean load required to fracture		p-Value
	Mean	SD
Material cementation approach
Ceramill COMP	2420	1027	.6
Cerasmart	2220	515
Bonding protocols
Total-etch	2238	750	.6
Self-etch	2402	875
Bonding protocolsin Ceramill COMP cementation
Total-etch	2532	930	.7
Self-etch	2308	1194
Bonding protocolsin Cerasmart cementation
Total-etch	1944	406	.06
Self-etch	2496	487

Data availability

All data supporting the reported results are available in a report available from the corresponding author upon request.