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

The Safety of Removing Fractured Nickel-Titanium Files in Root Canals Using a Nd: YAP Laser

The fracture of nickel-titanium (Ni-Ti) instruments during root canal instrumentation leads to compromised outcomes in endodontic treatments. Despite the significant impact of instrument facture during a root canal treatment, there is still no universally accepted method to address this complication. Several previous studies have shown the ability of a Neodymium: Yttrium-Aluminum-Perovskite (Nd: YAP) laser to cut endodontic files. This study aims to determine safe irradiation conditions for a clinical procedure involving the use of a Neodymium: Yttrium-Aluminum-Perovskite (Nd: YAP) laser for removing fractured nickel-titanium files in root canals. A total of 54 extracted permanent human teeth (n = 54) were used. This study involved nine distinct groups, each employing different irradiation conditions. Groups 1 s, 3 s, 5 s, 10 s, and 15 s simply consist of irradiation for 1, 3, 5, 10, and 15 s, respectively. After identifying the longest and safest duration time, four additional groups were proposed (labeled A, B, C, and D). Group A was composed of three series of irradiations of 5 s each separated by a rest time of 30 s (L5s + 30 s RT). Group B consisted of three series of irradiations of 5 s each separated by a rest time of 60 s (L5s + 60 s RT). Group C consisted of two series of irradiations of 5 s each separated by a rest time of 30 s (L5s + 30 s RT), and group D consisted of two series of irradiations of 5 s each separated by a rest time of 5 s (L5s + 5 s RT). In all groups, during the rest time, continuous irrigation with 2.5 mL of sodium hypochlorite (3% NaOCl) was carried out. The variation in temperature during irradiation was registered with a thermocouple during irradiation with different protocols. The mean and standard deviation of the temperature increase was noted. The calculation of the temperature was made as the Δ of the highest recorded temperature at the root surface minus (-) that recorded at baseline (37°). Additionally, scanning electron microscopy (SEM) was used after irradiation in all groups in order to assess the morphological changes in the root dentinal walls. The Nd: YAP laser irradiation parameters were a power of 3W, an energy of 300 mJ per pulse, a fiber diameter of 200 µm, a pulsed mode of irradiation with a frequency of 10 Hz, a pulse duration of 150 µs, and an energy density of 955.41 J/cm2. Our results show that the safest protocol for bypassing and/or removing broken instruments involves three series of irradiation of 5 s each with a rest time of 30 s between each series. Furthermore, our results suggest that continuous irradiation for 10 s or more may be harmful for periodontal tissue.

Canal disinfection using photo-chemically activated micro-bubble emulsion, Emblica officinalis, and Nd: YAP laser on smear layer and push-out bond strength of resin-based root canal sealer to the radicular dentin

AIMS

Evaluation of the effects of the latest root canal disinfectants i.e., Micro-bubble emulsion (MBE), Neodymium-doped yttrium aluminum perovskite (Nd: YAP), Emblica officinalis (E. officinalis) on the removal of smear layer (SL) and push out bond strength (PBS) of resin-based root canal sealer to the radicular dentin.

METHODS

The coronal portion of sixty single-rooted human mandibular premolar teeth was precisely sectioned at the cementoenamel junction. The canals were prepared to utilize ProTaper universal rotary files till F3. All the study specimens were divided into four groups based on the disinfection regime (n = 15) Group 1: 5.25% NaOCl, Group 2: MBE, Group 3: Nd: YAP laser and Group 4: E. officinalis extract. All the canals were then finally irrigated using 17% EDTA solution as a final disinfecting agent. SL removal assessment was performed on five samples from each group using a scanning electron microscope (SEM). Ten samples from each group were then filled with root canal filling material and the roots were sectioned. Push-out test and failure mode analysis were performed using the universal testing machine (UTM) and stereomicroscope respectively. The mean scores of PBS and SL removal were compared using a one-way analysis of variance (ANOVA) and Post Hoc Tukey's HSD test p = 0.05.

RESULTS

Group-2 (MBE + EDTA) coronal section (1.50 ± 0.23) exhibited the most effective eradication of SL from the canal space. The apical third of Group-1 (NaOCl+EDTA) (2.68 ± 0.82) samples demonstrated the least effective removal of SL from the radicular canal. The maximum score of PBS of AH plus sealer to the canal dentin was exhibited by the coronal section of Group-2 (MBE + EDTA) (9.55 ± 0.45 MPa) samples. However, the apical third of Group-1 (NaOCl+ EDTA) specimens (5.16 ± 0.32 MPa) demonstrated the minimum EBS.

CONCLUSION

MBE+ EDTA displayed better smear layer removal and bond integrity of AH plus sealer to the root canal dentin. Nd: YAP+ EDTA laser and E.officinalis displayed comparable outcomes to that of control NaOCl+ EDTA.

Twelve-Month Follow-Up of Different Dentinal Hypersensitivity Treatments by Photobiomodulation Therapy, Nd:YAG and Nd:YAP Lasers

In this retrospective study, data for three different laser-assisted approaches for the management of dentinal hypersensitivity (DH) was collected (n = 920 teeth). In total, 387 teeth were treated with photobiomodulation (PBM) therapy with 660 nm red light laser (PBM group), 327 were treated with the Nd:YAG laser (1064 nm) and 206 were treated with the Nd:YAP laser (1340 nm). To assess the effectiveness of each treatment, a visual analogue scale (VAS) was used, where zero represented no pain at all and ten represented the greatest pain. VAS was used before (T0), immediately after (T1), one week after (T2), four weeks after (T3), six months after (T4) and one year after treatment (T5). Means and standard deviations of VAS at different follow-up times were calculated. Values were compared within and between groups. Statistical significance was considered to be achieved when p-value was less than 0.05. Confidence level was proposed to be 99% with a P value lower than 0.001. Within groups, a statistically significant reduction was obtained when the mean value of VAS at T0 was compared with T5. At T5, the PBM group had the highest reduction of VAS (with mean value of 0), while the Nd:YAG and Nd:YAP groups had scores of 1.065 ± 0.674 and 4.665 ± 0.674, respectively. Conclusion: this retrospective study showed that PBM therapy and irradiation with Nd:YAG and Nd:YAP lasers are effective in managing DH pain. However, PBM therapy was the only procedure that showed complete pain relief at six and twelve months after treatment.

Effect of Nd:YAG Laser with/without Graphite Coating on Bonding of Lithium Disilicate Glass-Ceramic to Human Dentin

This study evaluated the effect of different surface treatments on the tensile bond strength between lithium disilicate glass-ceramics, resin cement, and dentin. Fifty truncated cone-shape glass-ceramics were divided into five groups (n = 10): G1, control: 10% hydrofluoric acid (HF); G2, Nd:YAG laser + silane; G3, Sil + Nd:YAG laser; G4, graphite + Nd:YAG laser + Sil; and G5, graphite + Sil + Nd:YAG laser. Fifty human third-molars were cut to cylindrical shape and polished to standardize the bonding surfaces. The glass-ceramic specimens were bonded to dentin with a dual-cured resin cement and stored in distilled water for 24 h at 37ºC. Tensile testing was performed on a universal testing machine (10 Kgf load cell at 1 mm/min) until failure. The bond strength values (mean ± SD) in MPa were G1 (9.4 ± 2.3), G2 (9.7 ± 2.0), G3 (6.7 ± 1.9), G4 (4.6 ± 1.1), and G5 (1.2 ± 0.3). Nd:YAG laser and HF improve the bond strength between lithium disilicate glass-ceramics, resin cement, and dentin. The application of a graphite layer prior to Nd:YAG laser irradiation negatively affects this bonding and presented inferior results.

Palatogingival groove and root canal instrumentation

AIM

To evaluate the morphology and impact of root canal preparation in maxillary incisors with palatogingival grooves (PGG).

METHODOLOGY

Twenty extracted human maxillary incisors with PGG were subjected to macroscopic analysis and scanning electron microscopy analysis (SEM). The following characteristics of the PGG were evaluated: depth, point of origin in the cingulum, extension and position on the lingual surface. Furthermore, the presence of calculus, communications between the root canal system and the PGG, and root resorptions were investigated. The root canals were subsequently instrumented with K-files of three consecutive sizes. The teeth were sectioned, and the axial plane of each tooth section was imaged using SEM before and after instrumentation. The distance between the root canal walls and the PGG was calculated according to the location. Additionally, the distance between canal walls and cementum was measured at three different sites, to verify if instrumentation influenced dentine removal on a specific wall in teeth with PGG. Statistical analysis was performed using the Mann-Whitney or Student's t-test (P < 0.05).

RESULTS

Macroscopic analysis revealed that a deep groove was most frequently observed (75%), followed by a depression/shallow groove (25%) (P < 0.05). PGG typically originated in the distal margin ridge of the cingulum (65%) (P < 0.05), extending only to the middle (45%) or up to the apical (50%) third of the root (P < 0.05). Additionally, PGGs were typically located on the distal aspect of the lingual surface (70%) (P < 0.05). Calculus was concentrated on the surface of the crown and cementum-enamel junction (P < 0.05). Communication between the root canal and PGG was present in 35% of teeth, and root resorptions were noted in 50% of teeth. The distance between the external root surface and the pulp cavity was significantly narrower after instrumentation (P < 0.05); however, root canal preparation did not influence dentine removal on the specific wall associated with the groove (P > 0.05).

CONCLUSIONS

Palatogingival grooves were characteristically deep and originated from the distal margin of the cingulum. Although it has been associated with a thinner root wall, root canal preparation did not influence the thickness of the specific wall in the maxillary incisors with PGG.

Q-Switch Nd:YAG Laser-Assisted Decontamination of Implant Surface

Peri-implantitis (PI) is an inflammatory disease of peri-implant tissues, it represents the most frequent complication of dental implants. Evidence revealed that microorganisms play the chief role in causing PI. The purpose of our study is to evaluate the cleaning of contaminated dental implant surfaces by means of the Q-switch Nd:YAG (Neodymium-doped Yttrium Aluminum Garnet) laser and an increase in temperature at lased implant surfaces during the cleaning process. Seventy-eight implants (titanium grade 4) were used (Euroteknika, Sallanches, France). Thirty-six sterile implants and forty-two contaminated implants were collected from failed clinical implants for different reasons, independent from the study. Thirty-six contaminated implants were partially irradiated by Q-switch Nd:YAG laser (1064 nm). Six other contaminated implants were used for temperature rise evaluation. All laser irradiations were calibrated by means of a powermetter in order to evaluate the effective delivered energy. The irradiation conditions delivered per pulse on the target were effectively: energy density per pulse of 0.597 J/cm², pick powers density of 56 mW/cm², 270 mW per pulse with a spot diameter of 2.4 mm, and with repetition rate of 10 Hz for pulse duration of 6 ns. Irradiation was performed during a total time of 2 s in a non-contact mode at a distance of 0.5 mm from implant surfaces. The parameters were chosen according to the results of a theoretical modeling calculation of the Nd:YAG laser fluency on implant surface. Evaluation of contaminants removal showed that the cleaning of the irradiated implant surfaces was statistically similar to those of sterile implants (p-value ≤ 0.05). SEM analysis confirmed that our parameters did not alter the lased surfaces. The increase in temperature generated at lased implant surfaces during cleaning was below 1 °C. According to our findings, Q-switch Nd:YAG laser with short pulse duration in nanoseconds is able to significantly clean contaminated implant surfaces. Irradiation parameters used in our study can be considered safe for periodontal tissue.

Clinical Evaluation of Nd:YAG Laser With and Without Dentin Bonding Agent for the Treatment of Occlusal Hypersensitivity

Purpose:

The aim of the present study was to evaluate and compare both the immediate and delayed desensitizing effects of the Nd:YAG (neodymium-doped:yttrium aluminum garnet; Nd3+:Y3Al5O12) laser with and without dentin bonding agent (DBA) on occlusal dentinal hypersensitivity (DH).

Methods and Materials:

Twenty-one patients with a total of 117 chronic occlusal hypersensitive teeth were selected. Each subject had at least three hypersensitive teeth. These teeth were randomly allocated into three groups: group 1, DBA on the occlusal surface; group 2, Nd:YAG laser (1064-nm wavelength, 30 mJ of energy, 10 pulse/s, 60 seconds, two times); and group 3, Nd:YAG laser (1064-nm wavelength, 30 mJ of energy, 10 pulse/s, 60 seconds, two times) with DBA. Pain was assessed using a visual analog scale after stimulation of the sensitive teeth by using the sharp tip of an explorer and an air blast prior to treatment and immediately, one week, one month, and three months after treatment by one blinded examiner.

Results:

A significant reduction in occlusal DH occurred at all time points in all of the experimental groups. The three groups showed significant improvements in discomfort immediately after treatment and after one week (p&lt;0.001), but the Nd:YAG laser with DBA group had greater efficacy when compared with the other groups. The Nd:YAG laser group and Nd:YAG laser with DBA group had no significant differences at one month and three months after treatment (p&gt;0.05); however, their desensitizing efficacy was superior to the DBA group.

Conclusions:

The Nd:YAG laser with DBA may be most effective in the long-term treatment of occlusal DH, although other measures also reduce DH.

Dentinal Hypersensitivity Treatment Using Diode Laser 980 nm: In Vivo Study

The discomfort of patients due to dentinal hypersensitivity (DH) is one of the main challenges that dentists face in daily practice. Difficulties in DH treatment gave rise to many protocols which are currently used. The aim of this clinical study is to evaluate the effectiveness of a new protocol on the reduction of dentinal hypersensitivity with diode laser 980 nm and the application of a graphite paste. 184 patients enrolled in the study, the degree of pain was evaluated by visual analog scale (VAS), graphite paste was applied on the exposed dentine before irradiation, the application of diode laser 980 nm with continuous mode, backward motion, tangential incidence of the beam in non-contact mode and a delivery output of 1 W. Fiber’s diameter was 320 μm and total exposure time depended on the time necessary to remove the graphite paste from the teeth. Statistical analyses were performed with Prism 5^® software. Pain in post-operative significantly decreased immediately after the treatment. Mean values stayed stable until a 6-month follow-up. The application is considered to be safe with long-term effectiveness.

Effects of different treatments on chemical and morphological features of eroded dentin

To evaluate the treatment of eroded dentin (Sensodyne Repair & Protect™, Er:YAG laser and combinations). The occlusal surfaces of 25 third molars were sectioned 1.5 mm in thickness. After an erosion cycle (5 min in demineralizing solution + 3 h in remineralizing solution; six cycles a day for 8 days), the samples were divided into five groups (n = 5): (E) erosion - control; (ES) erosion + Sensodyne Repair & Protect (NovaMin); (EL) erosion + Er:YAG laser (40 mJ, 10 Hz, 0.4 W, 50 μs, 3.1 J/cm², 63 W/cm²); (ELS) erosion + Er:YAG laser + Sensodyne; and (ESL) erosion + Sensodyne + Er:YAG laser. Following storage in ultrapure water (37 °C/14 days), the Ca/P ratio was evaluated by EDXRF and the morphology surfaces examined in SEM. The percentage of exposed dentin tubules was calculated. One-way analysis of variance and Tukey's test at 5% were used to treat the data. The Ca/P ratio was higher in E and ES groups. More exposed dentin tubules were found in E group and less exposed tubules were found in the ES group (p < 0.0001). When the toothpaste and laser were combined, the number of occluded dentin tubules was higher when laser was performed first (ELS). A positive effect was found when the laser and toothpaste were combined.

Non-surgical management of tooth hypersensitivity

Tooth sensitivity is a common complaint of patients in dental practices. Studies have demonstrated dentinal hypersensitivity to affect 10-30% of the population. There are various potential causes of tooth sensitivity and a variety of available treatment options. This narrative review will discuss the possible aetiology of this condition, as well as the treatment modalities available. A tailor-made treatment plan that starts with the most non-invasive treatment options and escalates only when those options have proven insufficient in alleviating symptoms should be provided for each patient. Only after all non- and less-invasive methods have failed to reduce the symptoms should more invasive treatment options, such as root-coverage, be considered.

Safety Irradiation Parameters of Nd:YAP Laser Beam for Endodontic Treatments: An In Vitro Study

Objective. Nd:YAP laser has several potentialities of clinical applications in endodontics. The aim of our study is to determine the safety range of irradiation parameters during endodontic application of Nd:YAP laser that can be used without damaging and overheating the periodontal tissue. Material and Methods. Twenty-seven caries-free single-rooted extracted human teeth were used. Crowns were sectioned to obtain 11 mm root canal length. Temperature increases at root surfaces were measured by a thermocouple during Nd:YAP laser irradiation of root canals at different energy densities. Canal irradiation was accomplished with a circular and retrograde movement from the apex until the cervical part of the canal during 10 seconds with an axial speed of 1 mm/s. Each irradiation was done in a canal irrigated continuously with 2.25% NaOCl solution. Results. Periodontal temperature increase depends on the value of energy density. Means and standard deviations of temperature increases at root surfaces were below 10°C (safe threshold level) when the average energy densities delivered per second were equal to or below 4981 J/cm² and 9554 J/cm², respectively, for irradiations using a fiber diameter of 320 μm and 200 μm. Conclusions. Within the limitations of this study and under specific irradiation conditions, Nd:YAP laser beam may be considered harmless for periodontal tissues during endodontic applications.