Comparative study of the adaptation of alkasite versus self-adhesive flowable restorations

Aim To compare the adaptation of self-adhesive flowable composite versus alkasite restorations with or without the use of an adhesive system. Materials and Methods A total of 30 noncarious maxillary premolars were selected and mounted 2 mm below the cemento–enamel junction in acrylic blocks. Trapezoidal class V cavities were prepared on the buccal surface of each tooth. The gingival margins of the prepared cavities were located 1 mm above cemento–enamel junction. All cavity margins were not bevelled. During the experiment time, all samples were kept in artificial saliva renewed daily at 37°C in an incubator to prevent dehydration. These were randomly divided into three groups (n = 10). Alkasite restorative material was applied in a bulk fill technique using a universal adhesive in samples of group I, while those of group II did not have any adhesive using the same restorative material and those of group III were restored using self-adhesive flowable composite (vertise flow). Specimens of the three tested groups were subjected to 500 thermal cycles from 5 to 55°C with 30 s. Dwell time and 15 s transfer time. They were all immersed in methylene blue dye 2% for 24 h in an incubator. Then all samples were examined under stereomicroscopy at ×40 to determine the percentage of gap free length along the entire margins. All specimens were then sectioned buccolingually to detect the percentage of internal gap length along the restoration/tooth interface. Results Regarding the marginal adaptation, the highest % of marginal free gap was recorded for group I, while the lowest was recorded for group II. Concerning the internal adaptation, it was found that the highest % of free gap was related to group I and III while the lowest was related to group II. Comparing the marginal versus internal % of gap free margins it was found that group I versus II showed a statistically significant difference. Also, group III versus II showed a significant difference. While group I versus III recorded no statistically significant difference. This was true at both marginal and internal % of free gaps. These findings indicated the responsibility of group II for the recorded differences since group II showed the least % of free gap margins and the highest percentage of total dye penetration values. Conclusions Within the limitations of this in vitro study, the adhesive system was effective in increasing the percentage of free gaps of tested groups whether marginal or internal. Recommendations The use of any composite material is not recommended without an adhesive system. Further in vitro studies providing more precise gap measurement are required.