Objectives: This prospective randomized single-blinded clinical study conducted in a split-mouth design examined the impact of an additional application of a flowable composite as a cavity liner in Class I and II composite restorations over 48 months.
Methods: According to the study protocol approved by the ethics committee, 100 restorations (Class I and II) were placed in 50 subjects exhibiting two cavities with restorative needs. One cavity was filled solely with a nano-hybrid composite (control group) and the second cavity in combination with an additional layer of a flowable composite (test group). A universal adhesive system was used in both groups in self-etch mode according to the manufacturer's instructions. Clinical evaluation was performed at baseline, 6, 12, 24, 36 and 48 months based on the modified USPHS/Ryge criteria.
Results: With a recall rate of 86%, 43 of the initial 50 enrolled patients were evaluated after 48 months. The cumulative survival rate for all restorations was 91.9%. A total of seven restorations (8.1%) were considered failures, three were due to the loss of vitality by endodontic treatment and four due to filling fractures. Five of seven failures were located in the test group (11.6%) and two restorations in the control group (4.7%). In both groups, this corresponds to significantly different cumulative success rates (control group: 95.3%; test group: 88.4 %) and annual failure rates (AFR) (control group: 1.2 %; test group: 2.9 %), respectively (p < 0.05; Mann-Whitney U test). Additionally, compared to the 24 and 36 month results, non-significant differences in parameters such as marginal discoloration and adaption were noted after 48 months.
Conclusions: The additional application of a flowable composite did not tend to be superior in this trial and should be further evaluated over a longer period of time. This study was supported by Voco GmbH, Cuxhaven, Germany. Support Funding Agency/Grant Number: VOCO GmbH, Cuxhaven, Germany. No. 31308004KZEP.