الفهرس 
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Abstract
This study evaluated the impact of scalpel finishing technique on marginal integrity of Class II direct composite and machinable composite restorations. Materials and methods:Forty-two extracted human sound molars were randomly assigned according to the type of restoration into 2 main groups: group 1 (n=21), restored with direct composite resin (universal submicron hybrid composite, Ever GlowA2 Brilliant, Coltene, Altstatten, Switzerland), group 2 (n=21), restored with indirect machinable composite resin (Brilliant crios, Coltene, Altstatten Switzerland). After cleaning and disinfection, all molars were prepared with MOD cavity preparation with 3mm depth and 3mm width. The specimens of group 1 were restored with direct composite while all the prepared specimens of group 2
were digitally scanned with intraoral scanning device T710 (MEDIT Corp, Seoul, Republic of Korea) to receive machinable composite resin inlay. Each main group were divided into 3 subgroups according to finishing technique (Scalpel, Disc, Strip). After finishing, all the specimens of group 1 and group 2 were subjected to 5000 cycles thermo-cycling aging. Then each specimen was sectioned in a buuco-lingual direction with (IsoMet4000, Buehler Ltd, Lake bluff, LL, USA) into two separate parts (n=84) (mesial part and distal part). All the specimens were exposed to a gold spraying system using (SPI- MODEL Sputter, Coter). For marginal integrity analysis, the specimens were analyzed by scanning electron microscope micrography (Jeol, Jsm 6510, LV, Japan). Then, data were statistically analyzed using Mann Whiteny test, the level of significance was established at significance level of p<0.05. Data did not follow normal distribution curve according to normality test . Results: Mann Whiteny test showed that, marginal integrity outcomes of both direct and machinable resin composite were not statistically significant different in any finishing techniques (p>0.05). Regarding to finishing techniques, both types of resin composite had no significant difference in gap proportions (MannWhiteny test, p>0.05), but there was a significant difference in overhang proportions (p<0.05) and marginal fracture proportions (p<0.05). The Mann Whiteny test revealed that there was significant difference in perfect margin proportions between finishing techniques for both types of composite (p<0.05 for direct and machinable composite.( Conclusions: Based on the extracted result, we concluded that both the scalpel and sof-lex disc finishing techniques exhibit a smoother restoration margin compared to the poly strip finishing technique, either with direct or machinable resin composite Class II restoration.