Clinical Outcome of Class I and II Restorations with and without an Intermediary Layer of a Flowable Composite after 24 Months: A Prospective, Randomized, Split-Mouth-Designed, Controlled and Single-Blinded Clinical Trial

Abstract

The aim of this clinical study was to evaluate the impact of an additional use of a flowable composite on the clinical success of Class I and II composite restorations. Furthermore, different clinical criteria were recorded to determine if the combination with a flowable material shows significant advantages compared to the composite material alone. In 50 patients, one cavity was solely filled with a nano-hybrid composite (control group) and the second cavity in combination with an additional layer of flowable composite (test group) using a universal adhesive system in the self-etch modus. Clinical assessments were performed according to the modified criteria proposed by USPHS/Ryge. After 24 months, 47 patients were examined resulting in a recall rate of 94%. The cumulative survival rate for all restorations after 24 months was 96.8%. Three restorations (3.2%) failed due to the loss of vitality. All failed restorations were located in the test group (6.4%), and none in the control group (0%). This resulted in a cumulative success rate in the control group of 100% and 93.6% in the test group, showing a significantly different annual failure rate (AFR) of 0% and 3.2%, respectively (p < 0.05; Mann–Whitney U-test). Beside the differences regarding the tooth vitality, success rate, and AFR, no significant influence of the flowable composite on the different evaluated clinical parameters could be detected. Therefore, the application of an additional layer of the flowable composite might have neither a positive nor a negative effect on composite restorations in clinical practice.

Influence of Cavity Lining on the 3-Year Clinical Outcome of Posterior Composite Restorations: A Randomized Controlled Clinical Trial

“…The comprehensive study protocol of this clinical trial is included in the previously published interim report [29]. However, for better readability of the work, parts of the methodology are also described in the current publication focusing on the 3-year results.…”

“…At the beginning, a thorough medical history, dental, and radiographic examination were performed to assess restorative needs, coronal, and apical pathologies, following the same procedure as reported in the 24-month results [29]. Restorative treatment in all cases was carried out after local anesthesia and adequate rubber dam isolation of the affected and selected teeth using the nanohybrid composite.…”

“…Seemann et al published the results of a survey in Germany which found that 80.1% of the participating dentists use a flowable composite for cavity lining [27]. Compared to most of the used flowable composite materials for this procedure the flowable resin material (Grandio ® SO Heavy Flow, VOCO GmbH, Cuxhaven, Germany) used in our clinical long-term study is a so-called heavy flowable nanohybrid composite with a relatively high viscosity compared to other flowable materials [28,29].…”

“…Many investigations evaluating the influence of lining with flowable composites on the clinical long-term performance of direct composite restorations [5,[29][30][31] reported favorable results. However, valid clinical data and evidence, particularly regarding a longer observation time than 24 months, especially for the high-viscosity flowable composite used, which might be more effective when used as a liner in the posterior teeth requiring increased strength [28], are still rare [29,32].…”

“…Many investigations evaluating the influence of lining with flowable composites on the clinical long-term performance of direct composite restorations [5,[29][30][31] reported favorable results. However, valid clinical data and evidence, particularly regarding a longer observation time than 24 months, especially for the high-viscosity flowable composite used, which might be more effective when used as a liner in the posterior teeth requiring increased strength [28], are still rare [29,32]. The aim of the present paper, following the study protocol developed and approved in advance [29] and examining the clinical outcome of the described material and material combinations over an observation period of several years, was to report the results after 3 years.…”