Pulpal and periodontal temperature rise during KTP laser use as a root planing complement in vitro

Evaluation of postoperative pain relief after pulpotomy using different procedures for disinfection and hemostasis in symptomatic irreversible pulpitis

Aim

This study aimed to evaluate postoperative pain scores after sodium hypochlorite (NaOCl) and KTP laser pulpotomies in the permanent teeth with symptomatic irreversible pulpitis retrospectively. Materials and Methods: This study is based on the records of patients treated with pulpotomy using sodium hypochlorite or KTP laser for disinfection and hemostasis at the Department of Endodontics. Sixty patients' molar teeth were treated with either NaOCl or KTP laser. Sodium hypochlorite was used on 31 teeth, and KTP laser was used on another 29 teeth, for disinfection and hemostasis. Initial bleeding control was obtained with saline. 2.5% NaOCl or KTP laser was applied to complete hemostasis. Calcium hydroxide was then placed on the chamber floor to cover the canal orifices. The permanent restoration was completed with composite resin. Pre and postoperative pain scores were recorded with a visual analog scale. The evaluation was performed on the 6^th, 24^th, 48^th, 72^nd hours, and 7^th days depending on the severity of the pain. Results: There was no significant difference between the groups in terms of demographic data and preoperative pain scores (P > 0.05). The postoperative pain score in the KTP laser group was significantly lower at the 24^th hour than in the NaOCl group (P < 0.05). No significant difference was found between the groups at other evaluated time intervals (P > 0.05). The greatest pain score was recorded at the 6^th hour in both groups.

Conclusion

Although the level of pain decreased significantly in both groups in the postoperative period, KTP laser-assisted pulpotomy provided better pain control, especially at the 24^th hour.

Thermal Changes in Root Surface of Primary Teeth During Root Canal Treatment With Diode Lasers: An In Vitro Study

Introduction: Increased temperature due to the application of laser during root canal disinfection may damage periodontium, alveolar bone, and permanent dental germ. The aim of this study was to evaluate the temperature increase of the external surface of primary roots due to the application of 810 nm and 980 nm diode lasers. Methods: A total of 58 extracted human primary teeth were prepared and randomly divided into two groups: (a) 810 nm diode laser and (b) 980 nm diode laser. Then, each group was divided into 4 subgroups based on the location of the temperature measurement, including subgroup 1: external root surface of primary anterior roots (A); subgroup 2: external root surface of posterior teeth at inter-root space (IS); subgroup 3: external root surface of posterior teeth at outer-root space (OS) and subgroup 4: external surface of furcation area of posterior teeth (F). Results: The mean temperature rise in group a (7.02±2.95ºC) was less than that of group b (10.62±4.59ºC) (P<0.001). Also, a significant difference was found between the laser groups in terms of the mean temperature rise of the external root surface at IS, OS and F, with higher temperature increase occurring in all points in laser b. The comparison of irradiation points in each laser showed a higher mean temperature rise for IS than OS, but this difference was only significant in group b (P<0.001). Conclusion: Within the studied parameters, 810 nm and 980 nm diode lasers should be used cautiously in primary root canals because of their temperature rise during their application.

Photobiomodulation with single and combination laser wavelengths on bone marrow mesenchymal stem cells: proliferation and differentiation to bone or cartilage

Tissue engineering aims to take advantage of the ability of undifferentiated stem cells to differentiate into multiple cell types to repair damaged tissue. Photobiomodulation uses either lasers or light-emitting diodes to promote stem cell proliferation and differentiation. The present study aimed to investigate single and dual combinations of laser wavelengths on mesenchymal stem cells (MSCs). MSCs were derived from rabbit iliac bone marrow. One control and eight laser irradiated groups were designated as Infrared (IR, 810 nm), Red (R, 660 nm), Green (G, 532 nm), Blue (B, 485 nm), IR-R, IR-B, R-G, and B-G. Irradiation was repeated daily for 21 days and cell proliferation, osseous, or cartilaginous differentiation was then measured. RT-PCR biomarkers were SOX9, aggrecan, COL 2, and COL 10 expression for cartilage and ALP, COL 1, and osteocalcin expression for bone. Cellular proliferation was increased in all irradiated groups except G. All cartilage markers were significantly increased by IR and IR-B except COL 10 which was suppressed by IR-B combination. ALP expression was highest in R and IR groups during osseous differentiation. ALP was decreased by combinations of IR with B and with R, and also by G alone. R and B-G groups showed stimulated COL 1 expression; however, COL 1 was suppressed in IR-B, IR-R, and G groups. IR significantly increased osteocalcin expression, but in B, B-G, and G groups it was reduced. Cartilage differentiation was stimulated by IR and IR-B laser irradiation. The effects of single or combined laser irradiation were not clear-cut on osseous differentiation. Stimulatory effects on osteogenesis were seen for R and IR lasers, while G laser had inhibitory effects.

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.

KTP laser therapy as an adjunctive to scaling and root planing in treatment of chronic periodontitis

OBJECTIVE

The main goal of periodontal treatment is to control infection and, thereby, curb disease progression. Recent studies have suggested that the use of a laser as an adjunct to scaling and root planing (SRP) might improve the effectiveness of conventional periodontal treatment. The aim of this study was to evaluate and compare the clinical effects of potassium-titanyl-phosphate (KTP) laser therapy in the treatment of chronic periodontitis in combination with traditional SRP.

MATERIALS AND METHODS

Twenty-four patients with untreated chronic periodontitis were treated using a split-mouth study design in which each side was randomly treated by SRP alone (control group) or KTP laser (0.8W, time on 50 ms, time off 50 ms, 30 s, 532 nm) followed by SRP (test group). In the distribution of the teeth (total = 124 teeth) in the patients, 106 (86%) were molars and 18 (14%) were premolars. The selected teeth were probed with a pressure-controlled probe, guided by stents. Clinical periodontal parameters including plaque index (PI), bleeding on probing (BOP), probing pocket depth (PPD) and probing attachment level (PAL) were recorded at baseline and at 2 and 12 months following therapy.

RESULTS

Statistical analysis demonstrated no differences between groups at baseline for all parameters (p > 0.05). BOP and PPD reductions and PAL gains were statistically significant both between baseline and 2 months and between baseline and 12 months in both groups (p < 0.05). The test group showed a greater reduction in PPD compared to the control group (p < 0.05). In addition, the test group showed a greater probing attachment gain compared to the control group (p < 0.05).

CONCLUSIONS

In patients with chronic periodontitis, clinical outcomes of conventional periodontal treatment can be improved by using an adjunctive KTP laser.

Effects of KTP Laser Bleaching on Traumatized Tooth Enamel

BACKGROUND

Bleaching of traumatized discolored teeth is considered an important issue in esthetic dentistry. Various methods have been introduced for bleaching, some of which may have adverse effects on soft or hard tissues of the tooth.

OBJECTIVES

The objective of the study was to evaluate the effects of KTP laser bleaching on enamel of traumatized teeth.

MATERIALS AND METHODS

A square of 36 mm(2) was chosen on the labial surface of 32 extracted teeth. The corners were drilled in order to indicate the location precisely. The shade of each sample was recorded and the teeth were divided into four groups, each with eight teeth: group A (Smartbleach with KTP laser for 30 seconds), group B (Smartbleach with G-Light for 5 minutes), group C (only Smartbleach for 10 minutes) and group D (control group with no bleaching). After one session of bleaching, shade assessment was performed again. In another experiment on nine teeth, Smartbleach with KTP laser was used for 150 seconds to 1500 seconds. The samples were critically processed and observed by using scanning electron microscope (SEM) to assess enamel damage. Data was statistically analyzed using Kruskal-Wallis test (confidence interval level were set at 95%).

RESULTS

Smartbleach was highly effective when used with KTP laser (P = 0.0419). Enamel damage was observed after frequent KTP bleaching and 750 seconds of KTP bleaching was recognized as the limit by morphological evaluation via SEM, indicating a major difference between under and over 750 seconds of bleaching.

CONCLUSIONS

Application of KTP laser may increase the bleaching effect of Smartbleach, nevertheless it may cause some enamel damage.

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.

Low energy KTP laser in oral soft tissue surgery: A 52 patients clinical study

Objectives: Since 1962 laser appliances have been used for soft tissues surgery of oral cavity with significant advantages compared to the traditional instruments: excellent bleeding control, possibility to avoid the use of suture, good patient compliance thanks to a decrease of intra- and post-operative discomfort and biostimulating effect. Unfortunately, the wavelengths so far used have been seen to cause, in association with an excellent ablation capacity, heat damage of the tissues that can decrease healing process and cause a greater discomfort to patients. The aim of this study was to evaluate the laser-assisted KTP laser surgery at low power in terms of characteristics of intervention and patients compliance. Study design: In this study, we describe the application of a new and recently introduced in dentistry wavelength, the KTP laser (532 nm), used with low power (1 Watt - CW), evaluating the time of interventions and, by a Numerical Rating Scale, the intra and postoperative pain. Results: KTP laser used at low power permits to obtain good pain control during operations that were carried out with only a topic anaesthetic (EMLA, Astratech), as shown in VAS tests. Good healing with limited or absent burning areas in treated portion of tissue. Conclusions: These preliminary study allows us to affirm that KTP laser with low parameters permits to perform oral surgery with good pain control and good wound healing. A greater number of clinical cases are however necessary to confirm the result obtained.

Key words: Laser, KTP, oral surgery, thermal increase.

Non-surgical periodontal therapy assisted by potassium-titanyl-phosphate laser: a pilot study

As the American Academy of Periodontology indicates, the treatment of chronic periodontitis should be achieved in the least invasive manner through non-surgical periodontal therapy. However, complete removal of subgingival plaque and calculus is hindered with increasing probing depth (PD) and furcation involvement using hand, sonic or ultrasonic instruments. Many authors have suggested that the use of laser as an adjunct to scaling and root planing (SRP) might improve the effectiveness of conventional periodontal treatment. The aim of this study was to evaluate potassium-titanyl-phosphate (KTP) laser in non-surgical periodontal therapy. Seven hundred and thirty sites with probing depths of 4-6 mm were involved in the study. The sites were divided into four groups: control (SRP, chlorhexidine gel 0.5%), group A (SRP, chlorhexidine gel 0.5%, three sessions of KTP laser irradiation); group B (SRP, three sessions of KTP laser irradiation) and group C (SRP, irrigation with povidone-iodine 10%, three sessions of KTP laser irradiation). KTP laser was used with the following parameters: output power 0.6 W, time on 10 ms, time off 50 ms, 30 s per irradiation, fluence 19 J/cm(2). All the sites showed improvement in all clinical parameters. Clinical attachment loss (CAL), pocket probing depths (PPDs) and bleeding on probing (BOP), especially in the lased groups, showed significant results (P < 0.001). Our experience showed KTP laser to be a significant help in SRP; nevertheless, more studies are necessary to confirm our results.

Innovative wavelengths in endodontic treatment

BACKGROUND AND OBJECTIVES

The sanitation of the root canal system and the adjacent dentin has always been a key requirement for successful endodontics. In recent years, various laser systems have provided a major contribution to this aim, namely the Nd:YAG-, the 810 nm Diode-, the Er:YAG-, and the Er,Cr:YSGG laser. Numerous studies could prove their efficiency within the endodontic procedure. Recently, two new wavelengths have been introduced to the field of oral laser applications: The KTP laser emitting at 532 nm and the 980 nm diode laser. The present in vitro investigation was performed to evaluate the effects of these laser systems focusing on their antibacterial effect in deep layers of dentin and their impact on the root canal dentin.

STUDY DESIGN/MATERIALS AND METHODS

Two-hundred slices of root dentin with a thickness of 1 mm were obtained by longitudinal cuts of freshly extracted human premolars. The samples were steam sterilized and subsequently inoculated with a suspension of either Escherichia coli or Enterococcus faecalis. After the incubation, the samples were randomly assigned to the two different laser systems tested. Each laser group consisted of two different operational settings and a control. The dentinal samples underwent "indirect" laser irradiation through the dentin from the bacteria-free side and were then subjected to a classical quantitative microbiologic evaluation. To assess the temperature increase during the irradiation procedure, additional measurements were carried out using a thermocouple. To assess the impacts on the root canal walls, 20 additional samples underwent laser irradiation at two different settings and were subjected to scanning electron microscopy.

RESULTS

Microbiology indicated that both laser systems were capable of significant reductions in both test strains. At an effective output power of 1 W, E. coli was reduced by at least 3 log steps in most of the samples by the tested wavelengths, with the best results for the KTP laser showing complete eradication of E. coli in 75% of the samples. E. faecalis, a stubborn invader of the root canal, showed minor changes in bacterial count at 1 W. Using the higher setting of 1.5 W, significant reductions of E. coli were again observed with both laser systems, where the lasers were capable of complete eradication of E. faecalis to a significant extent. There was no significant relation between the temperature increase and the bactericidal effect.

CONCLUSIONS

The present study demonstrates that both wavelengths investigated could be suitable for the disinfection of even the deeper layers of dentin and equal the results achieved by established wavelengths in state-of-the-art endodontics.