What is this about?
- Why abutment–crown retention is essential for long-term implant stability and restorative success.
- How surface treatment influences bonding, cement performance, and interface integrity.
- Why controlled, manufacturer-applied microtexturing may offer safer and more predictable outcomes than in-lab sandblasting.
Overview
Secure abutment–crown retention is critical to long-term implant success, and while design and cement choice matter, evidence shows that surface characteristics is often the deciding factor. Although in-lab sandblasting is widely used to improve micro-mechanical retention, it can cause well-documented clinical and occupational risks. Studies also demonstrate that increasing roughness beyond a certain threshold does not improve retention and may even weaken it. In contrast, manufacturer-applied microtexturing provides predictable, validated, and safer surface preparation, producing consistent microtopography without compromising component integrity or occupational safety. Prioritising these controlled treatments supports cleaner workflows, stronger and more reliable bonding, and improved long-term clinical stability.
One of the most fundamental factors behind a dental implant’s long-term success is secure and tight retention between the abutment and the crown. While a stable connection ensures optimal functionality, predictable load transfer, and patient comfort, poor retention remains one of the leading technical drivers of implant failure (1), (2), (3).
Optimal abutment-to-crown retention is dependent on multiple factors, including abutment design/geometry, surface condition, and cement type. While these parameters are often discussed individually, they interact in subtle ways that can influence long-term outcomes. For instance, once a bonding interface is contaminated, even an ideal abutment design remains problematic (4). Alternatively, a rougher abutment finish may sometimes lead to uneven cement application, compromising bond strength, seating accuracy, and marginal integrity (5), (6).
Key factors influencing abutment-crown retention
Over the years, various strategies have been explored to improve retention, focusing on structural design, cement formulation, and surface modification. Key developments have included:
- Adaptations in abutment structure – A taller abutment with minimal taper offers an increased surface area for bonding (7). Clinical positioning can, however, limit dimensions, particularly in cases with restricted interocclusal space.
- Improved compounds – Research suggests that resin-based cements provide higher retention rates than zinc phosphate or glass ionomer-type cements (8). In controlled studies, resin cements provide superior mechanical strength, more than three times greater than that of glass ionomer and ten times higher than zinc (9). However, resin-based compounds are not an ideal solution across all restoration scenarios, particularly when moisture control remains inadequate.
While abutment structure and compound selection contribute to improved retention, the micro- and macro topography of the abutment surface is often the decisive factor in achieving predictable and durable crown retention. (10)
Methods to enhance retention
Several methods are used to improve the surface area of an abutment, including the following:
- Manufacturer-applied surface treatments
- Chemical etching
- Silanization for zirconia
Fig. 1: An example of an abutment with a manufacturer-applied surface treatment, Straumann® Variobase® XC, with its patent-pending laser-treated surface, offers sufficient abutment-to-crown retention, negating the need to sandblast.
Perhaps the most commonly used method to enhance retention is in-lab sandblasting [TH1] (also known as air abrasion). During this process, ceramic particles, such as aluminium oxide, titanium oxide, or silica particles, are blasted at high velocity onto the abutment surface. The rationale is simple: the rougher the surface area, the higher the micromechanical retention of cement. While the intention is sound, these procedures can pose clinical and occupational risks.
Chairside sandblasting: common practice, hidden risks
While sandblasting can help improve short-term abutment-to-crown retention, it comes with technical, mechanical, and occupational risks that must be considered:
- The process of sandblasting can change the protective titanium-oxide layer on the abutment. This facilitates bacterial adhesion and colonization, increasing the risk of contamination. (11)
- Particles from the blasting material, such as alumina, can also become embedded in the surface, making it harder for cement to adhere properly. (12), (13).
- Overly aggressive sandblasting can create pits or divots, which can mean more cement is applied than normal. Overly thick cement can distort under load, cause improper abutment seating, or shrink during polymerization (a chemical process necessary for bonding). The latter can cause large microgaps that allow bacteria to enter (14).
- In zirconia abutments, sandblasting can create tiny cracks that reduce strength and make fractures more likely. (15), (16).
- It can also trigger subtle changes in the material over time, and the high-speed impact can leave residual stresses that make the abutment more fragile.
- Finally, inconsistent technique, such as excessive blasting or incorrect angulation, can further elevate these risks. (17)
Overall, sandblasting may enhance short-term retention; however, the evidence indicates that it can compromise surface integrity, material stability, and interface precision—potentially increasing the risk of microgap formation, bacterial contamination, and long-term mechanical complications.
Evidence and clinical guidance
Studies suggest that rougher is not always better. Reports evaluating abutment-to-crown retention agree that beyond a certain threshold of surface roughness, preservation does not linearly increase, and may, in fact, be weakened (17), (18). Taken together, these findings suggest an important clinical reality: controlled, validated surface preparation provides the most predictable outcomes.
Why controlled, manufacturer-approved treatments are safer and better for patients.
Validated surface modifications can improve abutment-to-crown retention while maintaining longevity, compatibility, and structural integrity. Manufacturer-prepared abutments are microtextured under carefully regulated industrial conditions, ensuring a consistent microtopography without compromising safety.
Fig. 2: A close-up view of the patent-pending laser-treated surface on Straumann® Variobase® XC.
Recent Straumann® developments introduced a proprietary laser-textured surface for the Variobase® XC for the Straumann iEXCEL™ system to enhance retention under controlled manufacturing conditions. This precision treatment creates a reproducible microtopography without altering the abutment’s geometry or material properties. Unlike conventional in-lab sandblasting, it is fully standardized, reducing variability, contamination risk, and the chance of structural compromise. Mechanical testing has shown significantly higher retention force, with laser-treated surfaces achieving up to 143% greater pull-out force values than untreated controls. (19) These advantages support more stable and predictable restorative outcomes, especially in demanding clinical situations, while preserving component integrity and system compatibility. Such precision-controlled surfaces provide consistent roughness and chemical stability while avoiding the dust and uncontrolled abrasion associated with in-lab modifications.
By following approved protocols and avoiding excessive or unregulated surface modification, clinicians can better preserve mechanical integrity, surface chemistry, and long-term biocompatibility. In practice, prioritizing manufacturer-applied surface treatments over in-lab sandblasting supports cleaner workflows, more stable restorations, and better patient outcomes.
Key takeaways
- Surface roughness can improve retention, but excessive or uncontrolled roughening may compromise strength, fit, and cleanliness.
- In-lab sandblasting carries clinical and occupational risks, including contamination, embedded particles, microcracks, and technique variability.
- Validated manufacturer-applied surface treatments support more consistent bonding, cleaner workflows, and long-term restorative stability.