Universidade Iguacu

Apical extrusion of bacteria is an unintended event that occurs during the chemical-mechanical preparation of infected root canals. Flare-ups and the spread of infection to periradicular tissues are possible consequences. This systematic review aimed to determine which type of engine-driven nickel-titanium systems, reciprocating or rotary, promote greater bacterial extrusion. Studies that compared manual and engine-driven systems or different brands of rotary instruments were also analyzed as a secondary objective.

Searches were performed in PubMed, Embase, Web of Science, Scopus, and ProQuest up to April 2024. Ex vivo studies that quantified the apical extrusion of bacteria comparing different instrumentation systems were included. The studies were critically assessed using a customized checklist.

Of the 4938 articles initially retrieved, 38 were selected for full-text reading and 35 were included in this review. Thirteen studies compared rotary and reciprocating instruments, 11 compared manual and engine-driven systems, and 11 compared different rotary instruments. Among the 13 studies comparing rotary and reciprocating systems, 5 reported greater bacterial extrusion with the rotary systems, 5 found no significant differences, and 3 reported mixed results. The available evidence indicates a similar or greater apical extrusion of bacteria with rotary systems compared to reciprocating instruments. Additionally, manual preparation is associated with significantly greater bacterial extrusion than the 2 engine-driven methods. The results varied across studies primarily due to methodological differences, particularly the instrumentation systems employed.

Rotary systems extrude similar or greater quantities of bacteria than reciprocating systems. Conversely, manual instrumentation promotes greater bacterial extrusion than the 2 engine-driven methods.

The Leishmania (Viannia) braziliensis Thor strain is composed of subpopulations with distinct biological features, as differences of the virulence profile in vitro and in vivo in murine model. As the surface of these parasites is the first contact with the host, this study assesses comparative approaches of surface membrane proteases of promastigotes and axenic amastigotes of L. (V.) braziliensis Thor strain and Thor03, Thor10, and Thor22 subpopulations, accessing differential profiles among these parasites. Here is explored the phospholipase C (PLC) property as a pivotal tool to selectively recover surface proteases of these parasites. The treatment of parasites with PLC yielded protein fractions with metalloprotease, cysteine protease, and serine protease activities, which were detectable by gelatin-SDS-PAGE and fluorogenic substrates and specific inhibitors, showing distinct profiles from both promastigotes and axenic amastigotes of the Thor strain, Thor03, Thor10, and Thor22 subpopulations. Data of protease activity quantitative in solution show metalloprotease as the highest activity, followed by cysteine protease and serine protease onto the surface of promastigotes and axenic amastigotes. The biological significance of these findings points to the potential of the Thor strain, helped by respective subpopulations, to adapt to hosts, as well as reinforcing the importance of this class of enzyme in the first hours of infection.

This study evaluated the shaping ability of the single-file XP-endo Shaper (XP-S) system, employing an extended working time, and the Reciproc Blue number 40/.06 (REC) instrument during the preparation of oval-shaped canals.

Eleven pairs of contralateral premolars with a single canal were divided into two groups (n = 11) according to the canal preparation protocol: XP-S (with an additional 45 seconds of instrumentation) and REC. Microcomputed tomography images captured before and after preparation were analyzed to assess morphometric measurements (prepared volume/area and unprepared canal walls at 10 mm and 4 mm from the foramen), centroid deviation (at 10 mm), dentin thickness with mesial or distal deviation, and canal-to-root ratio (at 1, 5, and 10 mm from the foramen).

In both groups, root canal preparation significantly altered all tested parameters across all evaluated cross-sections (P_Intra ≤ 0.003). No significant differences were observed between the groups in canal centralization, volume or surface area increase at 10 mm or 4 mm, nor in the number of unprepared canal walls at 10 mm. However, the REC system showed a greater reduction in unprepared walls in the critical apical zone (P_Inter = 0.047). The XP-S group exhibited greater reductions in mesial (P_Inter = 0.007) and distal (P_Inter = 0.028) dentin thickness at 1 mm from the foramen.

The REC instrument prepared more root canal walls than the XP-S system and promoted greater dentin preservation in the apical zone.