When “Good Enough” Contacts Are Not Good Enough

A newly published clinical study has drawn attention to one of the most overlooked aspects of restorative dentistry: proximal contact quality. While clinicians often focus heavily on material selection, bonding systems, and aesthetics, the study suggests that many restorative failures may originate from something far more basic—the quality of the contact area itself.

The investigation proposed a standardized floss-based classification system for evaluating proximal contact tightness chairside and assessed the quality of proximal contacts and marginal integrity across various direct and indirect restorations.

Why proximal contact matters

In natural dentition, proximal contacts are not static points but dynamic areas that help distribute occlusal forces, stabilize teeth and minimize food impaction. Improper contacts—whether excessively open or excessively tight—can contribute to:

• food lodgement,

• gingival inflammation,

• periodontal breakdown,

• flossing difficulty,

• tooth migration, and

• recurrent caries.

Although clinicians routinely verify contacts using dental floss, the study highlights that this assessment remains highly subjective in daily practice.

Only one-third of restorations demonstrated “appropriate” contact

The study evaluated 344 proximal surfaces across multiple restoration types and reported notable variability in contact quality:

34.6% demonstrated appropriate contact, 28.5% were excessively tight, 24.1% showed open contact, and 12.8% demonstrated poor contact quality.

These findings suggest that suboptimal proximal contacts may be far more common in routine practice than many clinicians realize.

The authors also emphasized that tactile floss assessment inherently carries perceptual variability, since floss tension, insertion angle, wetness, and operator interpretation can influence the perceived “snap” sensation.

Indirect restorations performed better

One of the most clinically relevant findings was the superior performance of indirect restorations compared with direct restorations.

Single crowns demonstrated better proximal contact quality and marginal integrity overall, likely because laboratory fabrication allows improved contouring and contact refinement before cementation.

Among direct restorations, glass ionomer cement restorations showed relatively favorable outcomes, whereas posterior composite restorations remained highly technique-sensitive. The study reinforced previous evidence showing that sectional matrix systems combined with separation rings continue to provide superior proximal contact predictability compared with wedges or hand instrumentation alone.

Mesial surfaces showed better outcomes than distal surfaces

The authors additionally observed a statistically significant association between contact quality and restoration surface location.