Assessment of the Periodontal Cementum Ablation Depth during Root Planing by an Er:YAG Laser at Different Energy Densities: An Ex Vivo Study.

INTRODUCTION: An important and non-adapted delivered energy of Er:YAG laser can eliminate the total thickness of root cementum during root planing. Conversely, the preservation of a partial layer of cementum covering the roots is vital for any periodontal ligament regeneration. Thus, the assessment of the cementum ablation depth produced by each energy density of Er:YAG laser is essential before considering its use for the periodontal planing and treatment of the cementum and root surfaces. AIM OF THE STUDY: Assessment of the cementum ablation depth at different energy densities of the Er:YAG laser is the aim of this study. MATERIALS AND METHODS: A total of 48 human caries free molars were collected and used in this study. Areas to be irradiated were delimited by two longitudinal grooves (0.5 mm depth). Roots were divided randomly into four groups (4 × n = 12). An Er:YAG laser (2.94 µm) was used with a side-firing tip (R600T) with a 600 µm diameter and a frequency of 20 Hz combined with a cooling system of air 6 mL/min and water 4 mL/min. We used a super short pulse mode (SSP: pulse duration: 50 µs). We used a single irradiation passage backward from apex to cervical parts at 1 mm/s with a slight contact and at an angle of 15° to 30° between the tip and the root surface. Different energies were selected: 30 mJ, 40 mJ, 50 mJ, and 60 mJ. RESULTS: Microscopic observations showed that the average of the ablation depth increased with the increase of the delivered energy from 30 mJ to 60 mJ. Mean values of the ablation depths were respectively as follows: 43.75 ± 4.89 µm for the energy of 30 mJ, 50.05 ± 3.72 µm for 40 mJ, 65.56 ± 10.35 µm for 50 mJ, and 74.80 ± 15.23 µm for 60 mJ. A statistically significant difference existed between the ablation depth of all groups. CONCLUSION: Based on our results, the depth of cementum debridement is related to the level of the delivered energy. The lowest energy levels (30 mJ and 40 mJ) can ablate the root cementum surface for a variable depth from 43.75 ± 4.89 µm to 50.05 ± 3.72 µm.

Photobiomodulation Therapy vs. Corticosteroid for the Management of Erosive/Ulcerative and Painful Oral Lichen Planus. Assessment of Success Rate during One-Year Follow-Up: A Retrospective Study.

Photobiomodulation (PBM) therapy is a promising approach for the management of inflammatory conditions and autoimmune lesions, such as oral lichen planus (OLP). The aim of this retrospective study was to assess the effectiveness of PBM in the management of painful and erosive/ulcerative OLP and to compare it with the standard of care that is the topical application of corticosteroids. 96 patients were included with erosive and painful OLP. 48 patients received PBM therapy and 48 received corticosteroids. Data was collected retrospectively on pain using the visual analogue scale; clinical aspects of lesions were assessed with the REU score, and the recurrence rate was noted. One session of PBM therapy with a helium-neon red light (635 nm) was carried out every 48 h for 6 weeks. Treatments were mainly made in contact mode, using a fiber with a diameter of 600 µm (0.6 mm). The output power of the laser beam was calibrated by a power meter. A delivered power of 0.1 W was used for 40 s in a continuous wave (CW), corresponding to a delivered energy of 4 J. The delivered energy density related to the fiber diameter was 1415 J/cm2. Each treated point was considered as 1 cm2 of diameter. PBM therapy within these parameters was carried out on each point until the totality of the lesion was covered, including the non-erosive OLP area. Furthermore, healthy mucosa within 5 mm of the lesion was also irradiated with the same conditions. This PBM treatment was performed during 6 consecutive weeks. The topical corticosteroid treatment consisted of cortisone application to cover the OLP 3 times/day for 6 weeks. Follow-up was made at 6 weeks and at 3, 6 and 12 months. After 6 weeks, both groups showed complete absence of pain, and a complete disappearance of ulcerative/erosive areas. No significant difference was found for both groups concerning the recurrence rate of erosive OLP during the follow-up period; values were 0% at 6 weeks for both groups and 79% and 87.5% for the corticosteroid and PBM group, respectively, at 12 months of follow-up. PBM is effective for managing OLP and is significantly similar to topical corticosteroids without any need for the use of medication and with no reported side effects.

Treatment of dentinal hypersensitivity by means of Nd:YAP Laser: a preliminary in vitro study.

OBJECTIVE: The aim of this study is to evaluate the effectiveness of Nd:YAP laser to seal dentinal tubules at different parameters. MATERIAL AND METHODS: 24 caries-free human wisdom impacted molars were used. The crowns were sectioned transversally in order to totally expose the dentin. The smear layer was removed by a 1 min application of EDTA. Each surface was divided into four quadrants, but only three quadrants were irradiated at a different output power setting (irradiation speed: 1 mm/sec; optical fiber diameter: 320 µm; tangential incidence of beam and in noncontact mode). Samples were smeared with a graphite paste prior to laser irradiation. All specimens were sent for SEM analysis. Pulp temperature increases in additional twenty teeth were measured by a thermocouple. RESULTS: Morphological changes in dentin surfaces depend on the value of used energy density. Higher energy densities (2 W-4 W; 200-400 mJ; pulse duration: 100 m sec.; and 10 Hz) induce higher dentin modifications. Our results confirmed that Nd:YAP laser irradiations can lead to total or partial occlusion of dentin tubules without provoking fissures or cracks. Measurements of pulp temperature increases showed that Nd:YAP laser beam can be considered as harmless for pulp vitality for following irradiation conditions: 2 W (200 mJ) to 4 W (400 mJ) with an irradiation speed of 1 mm/sec; fiber diameter: 320 micrometers; 10 Hz; pulse duration: 100 m sec; noncontact mode and in tangential incidence to exposed dentin. The perpendicular incidence of the laser beam on exposed dentin may injure pulp vitality even at low output power of 3 W. CONCLUSIONS: Nd:YAP laser beam was able to seal the dentin tubules without damaging dentinal surfaces and without harming pulp vitality. Nd:YAP laser is effective and may be safely used for future in vivo treatments of dentinal hypersensitivity under certain conditions.

Gingiva laser welding: preliminary study on an ex vivo porcine model.

OBJECTIVE: The use of lasers to fuse different tissues has been studied for 50 years. As none of these experiments concerned the oral soft tissues, our objective was to assess the feasibility of laser gingiva welding. MATERIALS AND METHODS: Porcine full-thickness gingival flaps served to prepare calibrated samples in the middle of which a 2 cm long incision was closed, either by conventional suture or by laser tissue welding (LTW). To determine the irradiation conditions yielding the best tensile strength, 13 output power values, from 0.5 to 5 W, delivered either at 10 Hz or in continuous wave mode, were tested on six indocyanine green (ICG) concentrations, from 8% to 13% (588 samples). Then, some samples served to compare the tensile strength between the laser welded and the sutured gingiva; the other samples were histologically processed in order to evaluate the thermal damage extent. The temperature rise during the LTW was measured by thermocouples. Another group of 12 samples was used to measure the temperature elevation by thermal camera. RESULTS: In the laser welding groups, the best tensile strength (p<0.05) was yielded by the 9% ICG saline solution (117 mM) at 4.5 W, 10 Hz, and a fluence of 31.3 kJ/cm(2). The apposition strength revealed no statistically significant difference (p<0.05) between the sutured and the laser welded gingiva at 4.5 W, 10 Hz, and 9% ICG solution. The mean temperature was 74±5.4°C at the upper surface and 42±8.9°C at the lower surface. The damaged zone averaged 333 µm at the upper surface. CONCLUSIONS: The 808 nm diode laser associated with ICG can achieve oral mucosa LTW, which is conceivable as a promising technique of gingival repair.

Dentinal tubules sealing by means of diode lasers (810 and 980 nm): a preliminary in vitro study.

OBJECTIVE: The aim of this study was to evaluate the effect on dentinal surfaces of diode lasers (810 and 980 nm) at different parameters. MATERIALS AND METHODS: Twenty-four caries-free human impacted wisdom teeth were used. The crowns were sectioned transversely in order to expose the dentin. The smear layer was removed by a 1 min application of ethylenediaminetetraacetic acid (EDTA). Each surface was divided into four quadrants irradiated at a different output power setting for each kind of laser: 0.8, 1, 1.6, and 2 W (energy densities: 2547, 3184, 5092, and 6366 J/cm(2), irradiation speed 1 mm/sec; optical fiber diameter: 200 µm; continuous and noncontact mode). Half of the samples were stained with a graphite paste. All specimens were sent for scanning electron microscopic (SEM) analysis. Pulp temperature increases in additional 20 teeth were measured by a thermocouple. RESULTS: Diode laser irradiations at 0.8 and 1 W led to occlusion or narrowing of dentin tubules without provoking fissures or cracks. The application of graphite paste increased the thermal effects in dentin. Measurements of pulp temperature showed that irradiations at 0.8 and 1 W for a period of 10 sec in continuous mode increased pulp temperature (T ≤2°C). CONCLUSIONS: Diode lasers (810 and 980 nm) used at 0.8 and 1 W for 10 sec in continuous mode were able to seal the dentin tubules. These parameters can be considered harmless for pulp vitality, and may be effective in the treatment of dentinal hypersensitivity.