Determination of Optimal Separation Times for Dual-Pulse SWEEPS Laser-Assisted Irrigation in Different Endodontic Access Cavities.

BACKGROUND AND OBJECTIVES: The purpose of this ex vivo study is to investigate whether it is possible to pre-determine and set the optimal separation times for the SWEEPS Er:YAG laser pulses pair during laser-assisted irrigation of endodontic root canals based on known lateral dimensions of the endodontic access cavities of different types of teeth. STUDY DESIGN/MATERIALS AND METHODS: As the optimal SWEEPS laser pulse pair separation for enhanced shockwave generation depends on the life-cycle of a single-pulse bubble, measurements of the oscillation time T B of the Er:YAG laser-generated bubble were made in 23 different endodontic access cavities of different types of teeth progressively widened in three different steps, into larger cavities, for a total of 69 cavities of different shapes and sizes. Different fiber-tip geometries (flat and radial), laser pulse energies (10 mJ and 20 mJ) and depth of fiber-tip insertion (2 mm and 4 mm) were also investigated. The obtained data were then analyzed using the reported relationship between the bubble oscillation time and the diameter of a cylindrically shaped cavity. RESULTS: A good fit to the relation analogue for ideal cylindrical cavities was found by taking the characteristic diameter of the access cavity to be represented by the cavity diameter either in the mesiodistal (D min ) or buccolingual (D max ) direction, or alternatively by the average of the two diameters (D ave ). The best fit was obtained for D min (R 2 = 0.73) followed in order by D ave (R 2 = 0.71) and D max (R 2 = 0.63). CONCLUSION: In spite of the endodontic cavities being non-cylindrical and of varied shape and size, the bubble oscillation time T B and the corresponding optimal SWEEPS separation time can be well predicted using a single characteristic dimension of the access cavity. This finding enables a simple and practical method for determining optimal conditions for shock wave generation and enhanced photodynamic streaming in differently shaped and sized root canals, leading to improved treatment efficacy and safety of root canal irrigation. Lasers Surg. Med. 2020. © 2020 The Authors. Lasers in Surgery and Medicine published by Wiley Periodicals LLC.

Disinfection of Root Canals with Laser-Activated Irrigation, Photoactivated Disinfection, and Combined Laser Techniques: An Ex Vivo Preliminary Study.

Objective: This study aimed to evaluate the efficacy of laser-activated irrigation using photon-induced photoacoustic streaming (PIPS®) and photoactivated disinfection (PAD) techniques and their combination to improve penetration and activation of toluidine blue in the endodontic space of teeth experimentally infected with Enterococcus faecalis. Materials and methods: Twenty-seven extracted single-root teeth were instrumented, sterilized, and infected with E. faecalis and divided into seven groups of three teeth each: Group A [sodium hypochlorite (NaClO) 5% hand irrigation], Group B [NaClO 5% hand irrigation+ethylenediaminetetraacetic acid (EDTA)+NaClO 5% activated by PIPS], Group C (EDTA+NaClO 5% activated by PIPS), Group D (toluidine blue activated by PAD), Group E (toluidine blue activated by PIPS and PAD), Group F (NaClO 5% hand irrigation+toluidine blue activated by PAD), and Group G (NaClO 5% hand irrigation+toluidine blue activated by PIPS and PAD). Finally, positive and negative group controls were prepared. The presence of biofilms after the treatments was assessed by the BioTimer assay. PIPS was performed with an Er:YAG laser (2940 nm, LightWalker, Fotona® d.o.o., Slovenia) at 20 mJ, 15 Hz, 0.3 W, and 50-µs pulse duration. PAD was performed with a 635 nm diode laser (Smart M, Lasotronix®, Poland) at 400 mW in continuous wave (CW). Results: When NaClO was used, significant decontamination (p ≤ 0.05) was obtained in all experimental groups with respect to the positive control, other than Group G. Irrigation with EDTA+NaClO activated by PIPS produced a higher level of decontamination than Group A (p ≤ 0.05). Significant results in reducing biofilm load compared with the control and Group A were observed when NaClO was coupled with toluidine blue activated by PAD (p ≤ 0.05). Conclusions: Disinfection of root canals can be obtained using a combination of different irrigants, photosensitizers, and activation protocols. EDTA+NaClO using the PIPS protocol and toluidine blue activated by PAD (both preceded by NaClO irrigation) can be considered effective tools. The possibility of replacing NaClO with toluidine blue, whatever the method of activation, should be further investigated.

Measurement of Pressures Generated in Root Canal During Er:YAG Laser-Activated Irrigation.

Objective: To measure distribution of pressures along the depth of the root canal during erbium-doped yttrium aluminum garnet (Er:YAG) laser-activated irrigation (LAI) with different modalities and fiber tip (FT) geometries. Background: A new LAI modality based on the delivery of synchronized pairs of Er:YAG laser pulses to generate enhanced irrigant streaming and shock wave emission was recently introduced. However, the influence of FT geometry on efficacy and comparison with single pulse modality is not yet presented. Methods: Pressures within a simulated root canal were simultaneously measured at 5 depths during LAI. Seven FT geometries (conical and cylindrical) and two modalities [Super Short Pulse (SSP) and dual pulse AutoSWEEPS] were compared. Results: Under the same conditions, average pressures using SSP at 20 mJ of laser energy ranged from 111 Pa for a conical 600 µm FT to 225 Pa for a flat 400 µm FT. The measured pressures for the SSP and the AutoSWEEPS at 20 mJ laser energy were 223 and 308 Pa at the most coronal level and 119 and 126 Pa at the apical constriction, respectively. Measured pressures and irrigant penetration depths at different root canal levels were found to be linearly correlated (R2 = 0.82; p < 0.01). Conclusions: The generated pressures get progressively reduced from the coronal toward the apical third of the root canal. A strong dependence on the FT design and laser modality was observed. Within the limitations of the study, the AutoSWEEPS modality is more effective than standard SSP in generating pressures within the root canal, without increasing the risk of extrusion.

Er,Cr:YSGG laser labial frenectomy: a clinical retrospective evaluation of 156 consecutive cases.

The labial frenum may impede oral hygiene and result in diastema between anterior teeth and traction of the attached gingiva. Surgical removal of the frenum during puberty has been recommended for these patients. This article clinically evaluates the efficacy of an Er,Cr:YSGG laser in removing the labial frenum in an adolescent and pre-pubescent population. Using an Er,Cr:YSGG laser at a power setting of 1.5 W or less and 20 to 30 pulses per second, a total of 156 frenectomies were performed on 143 children. Patients returned for recall visits at 3, 7, 21, and 30 days and at one, two, and three years. Surgical areas were checked for adverse events, recurrency of frenum, and functional complications. Patient acceptance was also evaluated by using the Wong-Baker FACES pain rating scale. Thirteen recurrences were reported in the adolescent population at 21 or 30 days, all of which required re-intervention; however, only two cases displayed recurrence of the frenum. None of the three pre-pubescent cases required additional intervention, maintaining acceptable clinical results after three years. Patient acceptance was very high, and no postoperative adverse events were reported.