This study investigated the effect on microleakage of different bonding agents and glass and polyethylene fibers inserted at gingival margins of class V composite restorations. Sixty premolars were sterilized. Class V cavities were prepared, 1 mm below the cementoenamel junction. Prepared tooth were randomly divided into 12 groups (n=10). In experimental groups fiber inserts were inserted at the gingival seat. The control groups had no inserts. Restorations were incrementally placed and polymerized. Specimens were then stored in water and thermocycled for 500 cycles, then immersed in 2% procion dye and sectioned buccolingually, then dye penetration was assessed. Data were analyzed with the Kruskal-Wallis test and analysis of variance of ranks. No significant differences were found among the types of fiber or the two types of composites. Significant differences were found between the bonding agents. SE and LS show significantly lower microleakage than NT in class V composite restorations in dentin.

This study investigated the effect on microleakage of different bonding agents and glass and polyethylene fibers inserted at gingival margins of class V composite restorations. Sixty premolars were sterilized. Class V cavities were prepared, 1 mm below the cementoenamel junction. Prepared tooth were randomly divided into 12 groups (n=10). In experimental groups fiber inserts were inserted at the gingival seat. The control groups had no inserts. Restorations were incrementally placed and polymerized. Specimens were then stored in water and thermocycled for 500 cycles, then immersed in 2% procion dye and sectioned buccolingually, then dye penetration was assessed. Data were analyzed with the Kruskal-Wallis test and analysis of variance of ranks. No significant differences were found among the types of fiber or the two types of composites. Significant differences were found between the bonding agents. SE and LS show significantly lower microleakage than NT in class V composite restorations in dentin.

Magister Scientiae Dentium - MSc(Dent) / To determine the total volumetric change and the relative speed of shrinkage of bulk fill flowable composites during polymerization. The volumetric change that occur during the polymerization of dental composite restorations are considered to be one of the most significant contributing factors when considering the failure in composite restorations. Volumetric shrinkage of more than 2% is considered to be enough to result in the occurrence of secondary caries resulting in fracture of restorations and failure in the adhesive layer of a resin restoration. The total volumetric change of dental resins can be attributed to three main factors: Firstly, the polymerization reaction that results in the formation of a polymer chain. Secondly, the increase of the exothermic thermal effects produced by the polymerization reaction and thirdly, light irradiance energy that is transferred to the dental resin.

In dental research, the morphometric assessment of restorations is a challenge. This also applies to the assessment of the length of interfacial adhesive defects in composite restorations as a measure of tooth-restoration bond failure. The determined mean fractions of interfacial gap length on enamel and dentin interfaces deviate from the true means (N → ∞), depending on the number (Ni) of object layers assessed. Cervical composite restorations were imaged with spectral domain optical coherence tomography (SD-OCT). The mean fractions of interfacial gap length on enamel and dentin were determined for an increasing number of OCT cross-sectional images (B-scans) per restoration and were graphically displayed as a function of the number of B-scans. As the number of B-scans increased, the calculated object means approached a range of ±2.5%. This analysis is appropriate for displaying the relationship between the determined mean fraction of interfacial gap length at the enamel/dentin-restoration interface and the number of B-scans.