Aim: To investigate the marginal adaptation and depth of cure of a flowable bulk-fill giomer (BEAUTIFIL Flow Plus X [BFP]), a flowable bulk-fill resin composite (PALFIQUE BULK FLOW [PBF]) bulk-fill resin composite, a packable bulk-fill giomer (BEAUTIFL-Bulk Restorative [BBR]), and two packable bulk-fill resin composites (X-tra fil [XF]) and (Filtek™ One Bulk Fill Restorative [FOB]). Materials and Methods: Twenty-five standardized class II cavities were prepared in the occlusomesial surfaces of maxillary premolars. A self-etching dental adhesive was used. All restorative materials were applied, and light cured according to their manufacturer's instructions. The teeth were subjected to 2500 thermal cycles between 5° C and 55° C. Epoxy resin replicas were obtained to examine the marginal by calculating the percentage of the continuous margin over the total margin length. using SEM at 200× magnification. For assessing the depth of cure, fifty specimens with 4 mm height were prepared. Vickers microhardness testing was used to assess the depth of cure was calculating the bottom-to-top ratio of each specimen. If this ratio reaches 0.80 or more, an adequate depth of cure is achieved. Results: Regarding marginal adaptation, there was no significant difference between different groups before (p=0.398) and after (p=0.644) thermocycling. Within all groups, there was a significant decrease in marginal adaptation after thermocycling (p<0.001). Regarding the depth of cure, all restorative materials achieved the required 0.8 bottom-to-top ratio.  There was a significant difference between different groups (p<0.001).  The highest value was found in BFP group (0.97±0.02), while the lowest value was found in BBR group (0.81±0.11). Conclusions: The marginal adaptation and depth of cure of bulk-fill giomer restorative materials are acceptable. Therefore, their use in restoration of 4-mm deep class II cavities is appealing.

Purpose: To assess the effect of pH cycling on surface microhardness and fluoride release of two modified nanoclay glass ionomer restorations (in vitro). Materials and Methods: A total of 180 permanent human caries free premolars were used. Class V were prepared on facial surfaces of the teeth. They were classified according to type of glass ionomer used for restoration of the cavities into three groups (60 teeth each); conventional glass ionomer medifill (A1), Dellite 43 modified glass ionomer (A2), and Dellite LVF modified glass ionomer (A3). Each group was moreover subdivided into three subgroups (20 teeth each) relative to the immersion solution used. The First subgroup remained in distilled Water (B1 control), the second subgroup was stored in artificial Saliva (B2) whereas the third subgroup was subjected to PH cycling (B3). Microhardness and fluoride release were measured after 7 and 30 days respectively. Results: There was a significant difference in the mean microhardness and fluoride release between the different materials after pH cycling (p≤0.001). PH cycling reduced the mean microhardness of the materials but induced the highest fluoride release. Conclusion: The proposed pH cycling model affected the microhardness of the tested materials while improved their fluoride release. Although the incorporation of montmorillonite into glass ionomer liquid improved the microhardness of the materials but it had yet, no effect on its fluoride release.

Background and Aim: Incorporation of Montmorillonite (MMT) nanoclay in restorative materials improves their mechanical properties in addition to biocompatibility, yet little is known about effects of MMT nanoclay-modified glass ionomer on dental pulp. This study aimed to evaluate pulp response of MMT nanoclay-modified glass ionomer as viable biocompatible material compared to resin-modified and conventional in dog model. Material and methods:MMT nanoclay was characterized using X-ray Diffraction (XRD) and Fourier Transform Infra-Red Spectroscopy (FTIR). Class V cavities were prepared in 90 dogs' teeth and divided into 3 groups (n=30): G1: conventional, G2: MMT nanoclay-modified, and G3: resinmodified glass ionomer. Then the jaws were dissected and demineralized at three-time intervals of 7, 30 and 60 days to evaluate the pulp response of the extracted teeth of each group microscopically and statistically using Kruskal Wallis and Friedman tests.Results: MMT nanoclay-modified glass ionomer (G2) group at 7 days was associated with reduced signs of inflammation with lesser interstitial edema, marked thickening of collagen fibers, mild inflammatory cell infiltrate and less destruction of the odontoblastic layer compared to the other two groups. Further healing was observed with nanoclay group after 30 days with significantly reduced inflammation and promoted regeneration of the odontoblastic layer and pulp tissue to reach a normal histological pulp architecture by 60 days. Conclusion:MMT nanoclay-modified glass ionomer is a promising biocompatible material that shows favourable pulp response over both conventional and resin-modified.