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INTRODUCTION:

Studies using conventional endodontic protocols show insufficient cleaning of root canal systems, often resulting in persistent infection and treatment failure. The GentleWave System (GWS; Sonendo, Inc, Laguna Hills, CA) has been shown to result in a higher tissue dissolution rate in a study using bovine muscle. The purpose of this study was to compare the debridement efficacy of the GWS with a traditional method for cleaning root canals.

METHODS:

Forty-five freshly extracted molars were randomly separated into 3 treatment groups (n = 15/group): group 1, no treatment; group 2, conventional rotary instrumentation and needle irrigation; and group 3, minimal instrumentation and the GWS treatment. Roots were prepared per standard histologic tissue processing after hematoxylin-eosin staining; sections were microscopically examined, and the percentage of soft tissue and debris remaining within the canals was morphometrically calculated. Images of the apical and middle regions of the roots were blindly analyzed.

RESULTS:

Significant differences (Welch’s t test) were found between groups 2 and 3 in both apical (P = .0015) and middle (P = .0179) regions of the mesial roots of mandibular molars and mesiobuccal roots of maxillary molars. Groups 2 and 3 resulted in cleaning 67.8% and 97.2% of the mesiobuccal and mesiolingual root canals of mandibular molars and the mesiobuccal canals of maxillary molars, respectively, whereas the results were similar among groups 2 and 3 in the apical and middle regions of distal roots. Groups 2 and 3 revealed significantly less debris than group 1 (P < .005).

CONCLUSIONS:

The GWS showed a significantly greater cleaning capacity and reduction in residual debris within the mesiobuccal and mesiolingual canals of mandibular molars and the mesiobuccal canals of maxillary molars than those cleaned conventionally.

Mercury contamination of oceans is prevalent worldwide and methylmercury concentrations in the mesopelagic zone (200-1000 m) are increasing more rapidly than in surface waters. Yet mercury bioaccumulation in mesopelagic predators has been understudied. Northern elephant seals (Mirounga angustirostris) biannually travel thousands of kilometres to forage within coastal and open-ocean regions of the northeast Pacific Ocean. We coupled satellite telemetry, diving behaviour and stable isotopes (carbon and nitrogen) from 77 adult females, and showed that variability among individuals in foraging location, diving depth and δ(13)C values were correlated with mercury concentrations in blood and muscle. We identified three clusters of foraging strategies, and these resulted in substantially different mercury concentrations: (i) deeper-diving and offshore-foraging seals had the greatest mercury concentrations, (ii) shallower-diving and offshore-foraging seals had intermediate levels, and (iii) coastal and more northerly foraging seals had the lowest mercury concentrations. Additionally, mercury concentrations were lower at the end of the seven-month-long foraging trip (n = 31) than after the two-month- long post-breeding trip (n = 46). Our results indicate that foraging behaviour influences mercury exposure and mesopelagic predators foraging in the northeast Pacific Ocean may be at high risk for mercury bioaccumulation.

OBJECTIVE:

The purpose of this study was to determine the effectiveness of laser-activated irrigation by photon-induced photoacoustic streaming (PIPS) using Er:YAG laser energy in decontaminating heavily colonized root canal systems in vitro.

MATERIALS AND METHODS:

Extracted single-rooted human teeth (n=60) were mechanically and chemically prepared, sterilized, inoculated with Enterococcus faecalis for 3 weeks, and randomly assigned to four groups (n=15): Group I (control, no decontamination), Group II (PIPS+6% NaOCl), Group III (PIPS+saline), and Group IV (6% NaOCl). PIPS settings were all preset to 50 μsec pulse, 20 mJ, 15 Hz, for an average power of 0.3 W. After decontamination, the remaining live microbes from all specimens were collected and recovered via plate counting of the colony-forming units (CFUs). Randomized root canal surfaces were examined with scanning electron microscopy and confocal laser microscopy. Mean variance and Dunnett’s t test (post-hoc test) comparisons were used to compare mean scores for the three groups with the control group.

RESULTS:

The CFU analysis showed the following measurements (mean±SE): Group I (control), 336.8±1.8; Group II (PIPS+NaOCl), 0.27±0.21; Group III (PIPS+saline), 225.0±21; and Group IV (NaOCl), 46.9±20.29. Group II had significantly lower CFUs than any other groups (p<0.05). Both imaging analyses confirmed levels of remaining bacteria on examined root surfaces.

CONCLUSIONS:

The use of the PIPS system along with NaOCl showed the most efficient eradication of the bacterial biofilm. It appears that laser-activated irrigation (LAI) utilizing PIPS may enhance the disinfection of the root canal system.

Background: Aerosols and droplets are produced during many dental procedures. With the advent of the droplet-spread disease severe acute respiratory syndrome, or SARS, a review of the infection control procedures for aerosols is warranted.

Types of studies reviewed: The authors reviewed representative medical and dental literature for studies and reports that documented the spread of disease through an airborne route. They also reviewed the dental literature for representative studies of contamination from various dental procedures and methods of reducing airborne contamination from those procedures.

Results: The airborne spread of measles, tuberculosis and SARS is well-documented in the medical literature. The dental literature shows that many dental procedures produce aerosols and droplets that are contaminated with bacteria and blood. These aerosols represent a potential route for disease transmission. The literature also documents that airborne contamination can be minimized easily and inexpensively by layering several infection control steps into the routine precautions used during all dental procedures.

Clinical implications: In addition to the routine use of standard barriers such as masks and gloves, the universal use of preprocedural rinses and high-volume evacuation is recommended.

The aim of this review is to give a survey of the use of high-power lasers for root canal cleaning and disinfection. There are two approaches: the first using a fiber in a dry root canal and exposing the root canal wall to the laser light with a spiral motion, and the other using the fiber in irrigant in the root canal or at the orifice. The laser-target interaction is different: a direct exposure of the substrate to laser light is the aim of the spiral motion, whereas the aim of the second technique is activation and agitation of the irrigant (laser activated irrigation / LAI). A limitation of the fiber is the straight forward emission. Modification of the fiber tip into a more conical shape allows for more lateral emission. This modification, however, does not result in far better cleaning and disinfection. Taking into account that all irrigants are water-based solutions, it is possible to create cavitation bubbles and to induce shockwaves and agitation in the irrigant with Erbium lasers. The newer technology allows for the use of low energy during a very short exposure time, resulting in high peak powers. Investigations on the latter topic have demonstrated that the creation of cavitation resulting in the induction of liquid agitation and shock waves in the irrigant may result in an in-depth cleaning and disinfection. Erbium lasers are the first choice for the activation of endodontic irrigants. Research in this respect has demonstrated that LAI performs “equal to” or “better than” ultrasonic activation. Other wavelengths with a solid absorption in water are now to be explored