How do palatal extensions and brands affect the retention of custom-made mouthguards? An in vitro study

Retention performance is a prerequisite for the protective effect of custom-made mouthguards (MGs). The current study aimed to evaluate the influence of palatal extensions and brands on the retention of MGs and to provide a theoretical basis for designing comfortable MGs.

Using an optimized fully dentate maxillary anatomical teaching model, two brands of sports MGs (Erkoflex (E) and Supsmile (S)) were created, with each brand preparing three identical splints, resulting in a total of six groups (E₁8, E₂8, E₃8, S₁8, S₂8, S₃8) with palatal margin extending 8 mm past the gingival margin. A testing machine applied a constant vertical traction force to each group of MGs at a speed of 50 mm/min until complete dislocation occurred, recording the peak stress value, with each group tested 30 times. Subsequently, each group of sports MGs was uniformly trimmed by 2 mm on the palatal edge, reducing the extensions to 6, 4, 2, and 0 mm, denoted as E₁ (6, 4, 2, 0), E₂ (6, 4, 2, 0), E₃ (6, 4, 2, 0), S₁ (6, 4, 2, 0), S₂ (6, 4, 2, 0), and S₃ (6, 4, 2, 0). The above experimental steps were repeated to obtain the retention force of MGs with different palatal extensions.

The length of the palatal edge significantly affects the retention force of the MG (p < 0.001), with longer edges resulting in higher retention forces. The influence of different brands (S and E) on the retention force of the MG is minimal; trend analysis indicates that 86.9% of the retention force of S brand MGs can be explained by the palatal extension, while for E brand MGs, this figure is 88.6%.

Within the limitations of this experimental study, different extension ranges of the palatal edge of the MG significantly influence its retention, with longer palatal extensions yielding higher retention rates. Additionally, under the constraints of S brand and E brand, the brand of the splint does not significantly contribute to the retention of the MG.