Bonding characteristics of impacted versus erupted permanent teeth

Area of Science:

• Dental materials science
• Adhesive dentistry
• Biomaterials engineering

Background:

• Tooth bonding is crucial for dental restorations.
• Optimizing etching times and understanding the effects of environmental factors like soaking are vital for bond longevity.

Purpose of the Study:

• To evaluate the effect of different etching times (0, 15, 30, 60 seconds) on the shear bond strength of erupted and impacted teeth.
• To compare bond strength between young and older individuals.
• To assess the influence of a 7-day soaking period on bond strength.

Main Methods:

• Standard bonding technique applied to teeth from young (12-24 years) and older (>50 years) individuals.
• Etching times varied: 0, 15, 30, and 60 seconds.
• Subgroups were soaked for 7 days; others served as controls.
• Shear bond strength tested using a universal testing machine (200-kg load cell, 5 mm/minute crosshead speed).

Main Results:

• No significant bond strength differences between young-impacted and young-erupted teeth at any etching time.
• Minimal bond strength variations observed across etching times of 15, 30, and 60 seconds.
• A significant decrease in bond strength was noted after a 7-day soak compared to a 24-hour soak, specifically for 30 and 60-second etching times.

Conclusions:

• Etching time and patient age have limited impact on initial bond strength in this study.
• Prolonged moisture exposure (7-day soak) can significantly compromise bond strength, particularly with longer etching durations (30 and 60 seconds).
• Clinical recommendations should consider the potential for hydrolytic degradation affecting long-term bond durability.