Resin penetration through submicrometer hiatus structures: a SEM and CLSM study

Area of Science:

• Dental Materials Science
• Biomaterials Engineering
• Nanotechnology in Dentistry

Background:

• Submicrometer hiatus structures are potential weaknesses in the hybrid layer of dentin bonding.
• Understanding resin penetration into these structures is crucial for predicting bond durability.
• Previous research has suggested their presence, but confirmation and detailed analysis are needed.

Purpose of the Study:

• To confirm the existence of submicrometer hiatus structures in dentin bonding.
• To quantify the degree of resin penetration through these formations.
• To analyze the uniformity and location of these structures across different adhesive systems.

Main Methods:

• Human molar dentin disks were prepared and bonded using three different fifth-generation dentin adhesive systems.
• Bonded specimens were sectioned and analyzed using Scanning Electron Microscopy (SEM) and Confocal Laser Scanning Microscopy (CLSM).
• Frequency, location, size, and resin penetration of submicrometer hiati were recorded and documented.

Main Results:

• Submicrometer hiatus structures were identified within the hybrid layer of all three dentin adhesive systems.
• Resin penetration was observed in 41.7% of SEM specimens and 83.3% of CLSM specimens.
• These structures were uniform in size (approx. 200 microm) and location, and penetration was not an artifact of desiccation.

Conclusions:

• Submicrometer hiatus structures are a consistent feature in fifth-generation dentin bonding.
• Significant resin penetration occurs through these structures, suggesting they may be infiltrated by bonding agents.
• The findings provide critical insights into the microarchitecture of the hybrid layer and its implications for dental restoration longevity.