Clinical accuracy outcomes of splinted and nonsplinted implant impression methods in dental residency settings.

OBJECTIVE: The splint technique of implant-supported restorations is a popular impression method; however, in-vivo studies showing the advantage of this method are scarce. The objective was to compare radiographic fit of the metal frameworks fabricated according to splinted or nonsplinted impression techniques. The null hypothesis was that splinting techniques would result in more accurate impressions. METHOD AND MATERIALS: A retrospective analysis was performed on 71 patients who had undergone multi-implant-supported rehabilitation in the years of 2012 to 2013. The treatment was carried out by three senior dentists or by residents in the department of Oral Rehabilitation at the Hebrew University Hadassah Medical Center. Each senior and the residents under his guidance treated patients consistently by only one different impression method: (1) no splint; (2) splinted transfers with pattern resin over dental floss scaffold; (3) splinting of transfers to impression tray with pattern resin. Orthoradial radiographs were used to determine if the metal framework fit the implant abutments. RESULTS: In total, 81 impressions and 285 implants were included in the study; 56 impressions were done by seniors and 25 by residents. There was no difference in success between the three methods when done by seniors (P = .76). The fixation to tray method was found to be significantly unsuccessful in the hands of residents (P = .01). CONCLUSION: Because the splint methods were not found to be more accurate, splinting the transfers might be an unnecessary step. Splinting of transfers to the impression tray is not recommended for inexperienced dentists.

Polyethyleneimine nanoparticles incorporated into resin composite cause cell death and trigger biofilm stress in vivo.

Incorporation of cross-linked quaternary ammonium polyethylenimine (QPEI) nanoparticles in dental resin composite has a long-lasting and wide antimicrobial effect with no measured impact on biocompatibility in vitro. We hypothesized that QPEI nanoparticles incorporated into a resin composite have a potent antibacterial effect in vivo and that this stress condition triggers a suicide module in the bacterial biofilm. Ten volunteers wore a removable acrylic appliance, in which two control resin composite specimens and two resin composite specimens incorporating 1% wt/wt QPEI nanoparticles were inserted to allow the buildup of intraoral biofilms. After 4 h, the specimens were removed and tested for bacterial vitality and biofilm thickness, using confocal laser scanning microscopy. The vitality rate in specimens incorporating QPEI was reduced by > 50% (p < 0.00001), whereas biofilm thickness was increased (p < 0.05). The ability of the biofilm supernatant to restore bacterial death was tested in vitro. The in vitro tests showed a 70% decrease in viable bacteria (p < 0.05). Biofilm morphological differences were also observed in the scanning electron microscope micrographs of the resin composite versus the resin composite incorporating QPEI. These results strongly suggest that QPEI nanoparticles incorporated at a low concentration in resin composite exert a significant in vivo antibiofilm activity and exhibit a potent broad spectrum antibacterial activity against salivary bacteria.

Effect of liquid-polish coating on in vivo biofilm accumulation on provisional restorations: part 1.

OBJECTIVE: Biofilm accumulation on provisional restorations may affect the surrounding tissues' integrity. The purpose of this study was to test in vivo biofilm formation on polymethyl methacrylate (PMMA) self-cured acrylic resin provisional crowns. METHOD AND MATERIALS: Three types of PMMA surfaces were tested: (1) polished, (2) polished and coated with bonding agent, and (3) polished and coated with light-cured liquid polish. After 12 hours in the oral cavity, the crown was removed and examined by confocal laser scanning microscope (CLSM) and scanning electron microscope (SEM). RESULTS: Biofilm, 250 Mum thick, was observed with CLSM on the polished acrylic surface. Significantly less bacterial accumulation was observed on the crowns coated with bonding agent, whereas no biofilm was observed on the crowns coated with liquid polish (P <.001). SEM examination confirmed these findings. CONCLUSIONS: Bonding resin or liquid polish coatings significantly reduce early biofilm formation, which in turn might affect the overall plaque accumulation on provisional restorations.