Determination of the edge permeability of restorations in the cervical region using a universal adhesive system in vitro: an experimental multicenter prospective controlled study

BACKGROUND:  The occurrence of microleakage in the gingival margins of restorations using composite materials is a frequently observed phenomenon, so the question arises about the ability of adhesive systems to hybridize dentin in this area. In the gingival margin of the restoration, microleakage is higher compared to the occlusal margin, as the thickness of the enamel decreases significantly in relation to the enamel-cement connection, and the enamel on the gingival wall of a V-class cavity is thinner than in the occlusal zone.

AIM: To evaluate the marginal permeability at the tooth-filling material interface in the cervical region using a universal adhesive system in comparison with a 5th-generation adhesive system after thermocycles in laboratory conditions.

METHODS: The marginal permeability at the seal-tooth border in the cervical area was determined: the main group: Tokuyama Universal Bond II (Tokuyama, Japan) (group 1), and the 5th-generation adhesive system (OptiBond Solo Plus (Kavo, Germany) (group 2) was used as the control groupon extracted tooth samples). The laboratory study included the following stages: sample preparation, the use of laboratory methods (thermal cycling of samples, staining, sawing of samples, photos with magnification), assessment of the degree of micro-flow of restorations by independent experts, statistical data processing in the SPSS Statistics program). Teeth removed for periodontal indications without carious lesions and large fillings were used to prepare the samples. The tests were carried out in accordance with GOST R 56924-2016 standard "DENTISTRY. Polymer reducing materials"

RESULTS: In group 1 (universal adhesive), there was no microleakage on the occlusal wall of the cavity in the enamel area. The experts' point assessment did not reveal any statistically significant differences (p>0.017). When assessing microleakage on the gingival wall in the samples of the first group, there were statistically significant differences between the assessments of 1, 2, and 3 experts (p<0.017).

In the second group of samples (5th generation adhesive), there were statistically significant differences between experts 2 and 3 in the assessment of microleakage on the occlusal wall (p<0.017). When assessing microleakage on the gingival wall, the differences between the assessments of 1 and 3 experts were statistically significant (p<0.017).

CONCLUSION: In group 1, using a universal adhesive system, and in group 2, using a 5th-generation adhesive system, there was no permeability (0 (0; 1) p<0.017) through the enamel wall. In the dentin/cement area, during the restoration of the cervical localization, there is a significant difference in micro-flow between group 1 (universal adhesive) (2 (0; 3)) and group 2 (adhesive system of the 5th generation) (2 (1;3) at p<0.017.