A summary of BISCO's comparison of All-Bond Universal and Scotchbond Universal Plus.
Read the original here: All-Bond Universal vs. Scotchbond Universal Plus: Which Formulation Delivers Higher Bond Strength?
“Universal” Doesn't Mean Identical
It's easy to treat universal adhesives as interchangeable. They share a name, a promise of simplicity, and often a similar list of indications. BISCO's latest article argues that the differences between them matter, because the monomers, solvents, water content, and acidity inside each bottle all affect how well and how long a bond holds.
To make the point, BISCO compares its own All-Bond Universal with Solventum's (3M) Scotchbond Universal Plus. In BISCO's view, the biggest difference between the two isn't the etch mode or the number of bottles. It's silane.
How the Two Formulas Differ
These figures come from BISCO. An independent lab measured the water content.
|
|
All-Bond Universal |
Scotchbond Universal Plus |
|
pH |
About 3.2 |
2.7 |
|
Water content |
2.5% |
8% |
|
Silane |
Not included |
Included |
|
Shelf life |
24 months at room temperature |
36 months (stored below 25°C/77°F) |
MDP at the core. All-Bond Universal's main functional monomer is MDP. BISCO notes that MDP is hydrophobic and has the highest log P (partition coefficient) of the common adhesive monomers,1 so it resists taking up water and helps the cured adhesive layer last. Citing published research, BISCO adds that MDP bonds directly to calcium, forming self-assembled nano-layers at the bonding interface, and that its stable hydrophobic interaction with collagen supports a more durable bond.
A mild pH from a low-water formula. All-Bond Universal has an ultra-mild pH of about 3.2, which lets it work with dual-cure and self-cure materials without a separate activator. BISCO reaches that pH with a low-water, high-ethanol solvent system. According to the studies BISCO cites, this helps avoid the water blisters and weak bonds that can form when leftover water is trapped in the adhesive layer. Scotchbond Universal Plus, by comparison, has a pH of 2.7 and contains 8% water, roughly three times All-Bond Universal's 2.5%.
Why BISCO Leaves Silane Out of the Adhesive
This is the detail BISCO says rarely shows up on side-by-side spec sheets. All-Bond Universal contains no silane and no fillers, and leaving silane out is a deliberate choice.
Silane is the coupling agent traditionally used to bond to glass-ceramic surfaces. BISCO points to studies showing that when silane is mixed directly into a low-pH universal adhesive, it can become chemically unstable over time and weaken the very bond it's there to create.2–4 According to its own public instructions for use, Scotchbond Universal Plus includes silane in its formula.
Does Built-In Silane Hold Up?
To test this, BISCO measured how well the silane in Scotchbond Universal Plus bonded to unetched lithium disilicate (e.max) as the product aged:
|
Aging condition |
Start |
16 weeks |
24 weeks |
|
Room temperature |
21.15 MPa |
21.35 MPa |
8.45 MPa |
|
Accelerated (37°C) |
21.15 MPa |
8.89 MPa |
9.53 MPa |
At room temperature, the bond held steady through 16 weeks and then fell by more than half by 24 weeks. Under accelerated aging, it dropped by 16 weeks.
BISCO's data on file also tracks a standalone silane primer over a much longer period. Porcelain Primer measured 32.44 MPa at the start and 32.7 MPa after 78 weeks of aging, essentially unchanged. BISCO's conclusion: silane holds its bond strength when it's applied on its own, in a formula designed for that single job, but not when it's folded into a low-pH universal adhesive.
The clinical takeaway: Silane itself isn’t the problem. As BISCO puts it, silane works best as its own dedicated step, not stored for months in an acidic adhesive bottle. That’s why BISCO pairs All-Bond Universal with a standalone silane primer, BisSilane or Porcelain Primer, for bonding glass ceramics, instead of building silane into the adhesive.
Matching the Adhesive to the Case
Direct composites with good isolation: Either universal adhesive is likely to perform well.
Glass ceramics and lithium disilicate: Use a separate silane primer, such as BisSilane or Porcelain Primer, with your adhesive.
Zirconia: All-Bond Universal's MDP can bond to zirconia, though BISCO still recommends an MDP primer such as Z-Prime Plus.
Dual-cure and self-cure materials: All-Bond Universal's mild pH means it doesn't need a separate activator.
Key Takeaways
· According to BISCO, the biggest difference between All-Bond Universal and Scotchbond Universal Plus is silane: one leaves it out, the other builds it in.
· All-Bond Universal is built on MDP, a water-resistant monomer that bonds to calcium and supports a durable bond, according to the research BISCO cites.
· All-Bond Universal is less acidic (pH about 3.2 vs. 2.7) and contains roughly a third of the water (2.5% vs. 8%), which helps prevent water-related bond weakness.
· Studies cited by BISCO show that silane mixed into a low-pH universal adhesive can become unstable over time.2–4
· In BISCO's aging test, the built-in silane in Scotchbond Universal Plus fell by more than half by 24 weeks at room temperature, and by 16 weeks under accelerated aging.
· A standalone silane primer held steady for 78 weeks, which supports adding a separate silane step for glass ceramics.
Frequently Asked Questions
Do I need a separate silane primer if my universal adhesive already contains silane?
For glass ceramics such as lithium disilicate (e.max), BISCO recommends one. Studies show that silane mixed into a low-pH universal adhesive can become unstable over time.2–4 In BISCO’s own testing, a standalone silane primer held its bond strength for 78 weeks.
Why doesn’t All-Bond Universal contain silane?
BISCO left silane out on purpose. Silane doesn’t stay stable in an acidic, low-pH formula.2–4 BISCO instead pairs All-Bond Universal with a separate silane primer, such as Porcelain Primer, for glass-ceramic restorations.
Does All-Bond Universal need an activator with dual-cure or self-cure cements?
No. According to BISCO, its mild pH of about 3.2 lets it work with dual-cure and self-cure materials without a separate activator.
Can All-Bond Universal bond to zirconia on its own?
Its MDP monomer can bond to zirconia. BISCO still recommends an MDP-containing primer, such as Z-Prime Plus, for reliable adhesion.
References
1. Suh BI. Adhesive systems. In: Principles of Adhesion Dentistry: A Theoretical and Clinical Guide for Dentists. Newtown, PA: AEGIS Publications; 2013. p. 44–47.
2. Yao C, Yu J, Wang Y, Tang C, Huang C. Acidic pH weakens the bonding effectiveness of silane contained in universal adhesives. Dent Mater. 2018;34(5):809–818.
3. Yoshihara K, Nagaoka N, Sonoda A, Maruo Y, Makita Y, Okihara T, Irie M, Yoshida Y, Van Meerbeek B. Effectiveness and stability of silane coupling agent incorporated in ‘universal’ adhesives. Dent Mater. 2016;32(10):1218–1225.
4. Kim YR, Kim JH, Son SA, Park JK. Effect of silane-containing universal adhesives on the bonding strength of lithium disilicate. Materials (Basel). 2021;14(14):3976.
Additional references, along with BISCO’s data on file, are listed in the original article. View the full reference list on BISCO’s blog.