The role of bacterial infections in rheumatoid arthritis development and novel therapeutic interventions: Focus on oral infections.

BACKGROUND: Rheumatoid arthritis (RA) represents a primary public health challenge, which is a major source of pain, disability, and socioeconomic effects worldwide. Several factors contribute to its pathogenesis. Infections are an important concern in RA patients, which play a key role in mortality risk. Despite major advances in the clinical treatment of RA, long-term use of disease-modifying anti-rheumatic drugs can cause serious adverse effects. Therefore, effective strategies for developing novel prevention and RA-modifying therapeutic interventions are sorely needed. OBJECTIVE: This review investigates the available evidence on the interplay between various bacterial infections, particularly oral infections and RA, and focuses on some potential interventions such as probiotics, photodynamic therapy, nanotechnology, and siRNA that can have therapeutic effects.

Antimicrobial photodynamic therapy: modern technology in the treatment of wound infections in patients with burns.

BACKGROUND: Staphylococcus aureus is one of the most frequently isolated microorganisms from burn wounds. Antimicrobial photodynamic therapy (aPDT) is a new strategy that may improve antimicrobial treatment. METHOD: This study evaluated three meticillin-resistant Staphylococcus aureus (MRSA) and three meticillin-sensitive Staphylococcus aureus (MSSA) clinical isolates, which produced a biofilm with 0.1mg/ml Toluidine Blue O (TBO) (Sigma-Aldrich, Germany) with an energy density of 45J/cm2 and 90J/cm2, for MRSA and MSSA, respectively. The antibiofilm potential of aPDT with TBO was analysed using crystal violet assays and scanning electron microscopy. RESULTS: TBO-aPDT significantly degraded the biofilm formed by MRSA and MSSA clinical isolates (p<0.05). CONCLUSION: Our results indicated that aPDT is an effective approach to combat bacterial biofilms associated with burn wound infection. aPDT could provide a supplemental to the treatment of wound and tissue infection, and patients with burns may benefit from combined treatments.

Evaluating the effect of mechanical debridement with adjunctive antimicrobial photodynamic therapy in comparison with mechanical debridement alone on the peri-implant parameters in type 2 diabetic mellitus patients with peri-implantitis: a systematic review and meta-analysis.

BACKGROUND: Type 2 diabetes mellitus (T2DM) is a major risk factor for localized diseases such as peri-implantitis that may affect ideal implant treatment. This study was aimed to evaluate the effect of mechanical debridement (MD) + antimicrobial photodynamic therapy (a-PDT) in patients with peri-implantitis who have T2DM in terms of bleeding on probing (BOP) and probing depth (PD) as primary outcomes and plaque index (PI) and crestal bone loss (CBL) as secondary outcomes. METHODS: Publications compared outcomes between MD + aPDT and MD alone in T2DM patients with peri-implantitis, containing more than 3-month follow-up duration, were involved in the systematic review and meta-analysis. Literature until July 2023 using MEDLINE (through PubMed), Scopus, Cochrane Library, Embase, Web of Science, and Google Scholar were collected. RESULTS: Two randomized controlled trials (RCTs, 88 individuals) and one controlled clinical trial (CCT, 67 individuals) with follow-up periods ranged from 3 to 12 months were recruited. All studies used diode laser with wavelengths ranged from 660 to 810 nm. The results demonstrated that the MD + aPDT group showed significant benefits for BOP reduction after 6 months (SMD = -2.15, 95% CI: -3.78 to -0.51, p = 0.01). However, a great amount of heterogeneity was observed (I2 = 91.52%, p < 0.001). Moreover, there was a significant difference between MD + aPDT and MD alone groups in CBL (SMD = -0.69, 95% CI: -1.07 to -0.30, p < 0.001). In addition, homogeneity assumption was satisfied (I2 = 22.49%, p = 0.28). Significant differences in PD and PI reduction were not found except for PI reduction after 3 months (SMD = -0.79, 95% CI: -1.24 to -0.33, p < 0.001. Also, no heterogeneity was observed (I2 = 0.00%, p = 0.47). CONCLUSION: Given that high heterogeneity in BOP and PD outcome was found in this systematic review, future long-term CTs with MD + aPDT should be examined to arrive at a firm conclusion.

Effects of diode and erbium lasers as an adjunct to scaling and root planing on clinical and immunological parameters in non-surgical periodontal treatment: a split-mouth randomized controlled clinical trial-"effects of lasers on immunological parameters".

This study evaluated the effects of diode and erbium lasers, as an adjunct to scaling and root planing (SRP), on clinical and immunological parameters in non-surgical periodontal therapy. In this split-mouth randomized controlled clinical trial, 17 participants with at least one periodontally involved tooth in each quadrant received oral hygiene instruction and full-mouth SRP. At baseline, probing pocket depth (PPD), clinical attachment level (CAL), bleeding on probing (BOP), and full-mouth plaque index (FMPI) were measured, and gingival crevicular fluid (GCF) sampling was performed. Next, one random quadrant in each participant received 940 nm diode laser (1 W, continuous-wave), and another quadrant received 2780 nm Er,Cr:YSGG laser (1.5 W, 30 Hz) irradiation. The GCF levels of interleukin (IL)-10 and matrix metalloproteinase (MMP)-13 were measured at baseline, and after 2 and 6 months using ELISA. The clinical parameters were also measured. Data were analyzed by repeated measures ANOVA. Significant clinical improvement was noted in all groups (P < 0.05). CAL in the control group was higher at 6 months than 2 months. The increase in IL-10 in erbium group was significantly greater than that in other groups (P < 0.001). The MMP-13 level was significantly lower in laser groups with greater reduction in erbium group (P < 0.001). Application of 940 nm diode and 2780 nm Er,Cr:YSGG lasers as an adjunct to SRP significantly decreased the GCF level of MMP-13, with no significant clinical advantage over SRP monotherapy. Application of 2780 nm Er,Cr:YSGG laser in addition to SRP increased the GCF level of IL-10.Trial registration numbers: IRCT20140318017053N11 and IRCT20140318017053N9.

Push-out bond strength of two calcium silicate-based cements used for repair of artificial furcal perforation following different power outputs of Nd:YAG laser.

Proper bond strength of endodontic materials is an essential factor in the final success of root canal treatments, including perforation repairs. This study was designed to evaluate the effect of two power outputs of Nd:YAG laser (1064 nm) on push-out bond strength (PBS) of ProRoot mineral trioxide aggregate (MTA) and calcium-enriched mixture cement (CEM Cement) in the repair of artificial furcal perforations. This ex vivo study enrolled 66 extracted human molars. After preparing the access cavity, perforations were created on the floor of the pulp chamber with a diameter of 1.4 mm. The teeth were randomly distributed into the following six groups according to the repair material (MTA and CEM) and power output of laser irradiation (1 W and 1.5 W); A: MTA (case), B: CEM (case), C: Nd:YAG (1 W)/MTA, D: Nd:YAG (1 W)/CEM, E: Nd:YAG (1.5 W)/MTA, and F: Nd:YAG (1.5 W)/CEM. Then, a universal testing machine was utilized to assess the PBS. Data analysis was performed using ANOVA and T tests. Significant level was considered at P < 0.05. The highest mean ± SD of PBS was noted in Group Nd:YAG (1 W)/MTA (58.92 ± 36.13), followed by Nd:YAG (1.5 W)/MTA > Nd:YAG (1.5 W)/CEM > Nd:YAG (1 W)/CEM > MTA > and CEM. A significant difference was noted between laser and non-laser applications (P < 0.05). However, the increase of power output from 1 to 1.5 W had no significant influence on PBS (P > 0.05). The PBS of MTA groups was always significantly greater than that of CEM groups (P < 0.05). Although Nd:YAG laser irradiation positively influenced on PBS values in both material studied, increasing power output was not effective.

Efficacy of compound topical anesthesia combined with photobiomodulation therapy in pain control for placement of orthodontic miniscrew: a double-blind, randomized clinical trial.

This study aims to investigate the effect of compound topical anesthetic (CTA) application combined with photobiomodulation therapy (PBMT) on the level of pain perceived during placement of miniscrews and 24 h post the procedure in the buccal side of the maxillary bone. This randomized, prospective, single-center, split-mouth, double-blinded study included 25 subjects (12 males and 13 females, aged 16 to 35). Two anesthetic techniques before implantation were performed including Profound gel +PBM with 980 nm diode laser and local anesthesia with 2% lidocaine hydrochloride. Then, the miniscrews with the size of 1.6 mm in diameter and 8 mm in length were placed with a hand driver in the buccal side of the maxillary bone. The pain immediately after miniscrew placement (T1), also 12 h (T2), and 24 h (T3) post the procedure were collected by visual analog scale (VAS). Data were analyzed by SPSS version 22. There were no statistically significant differences in mean VAS scores within or between CTA combined with PBMT or injection applications, immediately after miniscrew placement (P = 0.75), 12 h after miniscrew placement (P = 0.4), and 24 h after miniscrew placement (P = 1.0). Compound topical anesthetic combined with PBMT provided adequate local anesthesia for the placement of miniscrews in the buccal side of the maxillary bone.

Effect of antimicrobial photodynamic therapy with different photosensitizers and adhesion protocol on the bond strength of resin composite to sound dentin.

OBJECTIVES: The aim of this study is to evaluate the influence of the antimicrobial photodynamic therapy with phycocyanin and toluidine blue on the bond strength of resin composite to the sound dentin. MATERIALS AND METHODS: The samples include 120 tooth blocks taken from 60 human extracted sound third molar teeth. They were randomly divided into 12 groups and disinfected with two different photosensitizers (Phycocyanin and Toluidine blue) activated by 635 nm diode laser for aPDT procedure. Then two different protocols (total-etch and self-etch) of universal adhesive system (G-Premio BOND, GC Dental Products CORP. Japan) were applied. The samples then filled with resin composite (Gradia® Direct, GC Dental Products CORP. Japan). After 10000 cycles of thermocycling, all samples were subjected to the micro shear bond strength (µSBS) test using a universal testing machine (1 mm/min). The data were analyzed with One Way ANOVA. RESULTS: The effect of aPDT using both photosensitizers (phycocyanin and toluidine blue O) on the bonding strength to dentin was not significant (P>0.05). However, the bonding strength of total etch groups was reduced significantly (P<0.05) after aPDT using both photosensitizers. Phycocyanin self-etch group showed the greatest bonding strength (19.48 ± 3.89 MPa) in comparison to other aPDT groups. No significant reduction after thermocycling in dentin bond strength was observed in all groups (P>0.05), with exception of control total etch groups, which showed significant difference (P<0.05). CONCLUSION: aPDT using toluidine blue O and phycocyanin has no adverse effect on bonding to sound dentin when using universal adhesive in self-etch protocol. CLINICAL RELEVANCE: Phycocyanin is more recommended to be used in aPDT in comparison to toluidine blue as a natural photosensitizer.

Effect of different activations of silver nanoparticle irrigants on the elimination of Enterococcus faecalis.

OBJECTIVES: This study aimed to compare the efficacy of silver nanoparticles (AgNPs) irrigating solution alone and following activation with photon-induced photoacoustic streaming (PIPS), photodynamic therapy (PDT) with indocyanine green (ICG), passive ultrasonic irrigation (PUI), and manual dynamic activation (MDA) method for elimination of Enterococcus faecalis (E. faecalis) from the root canal system. MATERIALS AND METHODS: A total of 59 extracted human single-rooted teeth were collected and prepared. E. faecalis was inoculated into the root canals and incubated for 4 weeks. The teeth were then randomly divided into five experimental groups (n = 10): the AN group, irrigation with AgNPs alone; the AN/ICG/DL group, irrigation with AgNPs and ICG, then activation with diode laser; the AN/PIPS group, irrigation with AgNPs and activation with 0.3 W Er: YAG laser; the AN/MDA group, irrigation with AgNPs and activation with tapered gutta-percha; and the AN/PUI group, irrigation with AgNPs and activation with ultrasonic. Also, two control groups of irrigation with 2.5% sodium hypochlorite (n = 5) and no intervention (n = 4) were also used. Samples were collected from the dentinal chips before and after the intervention, and the percentage of reduction in colony count was calculated. RESULTS: A significant reduction in E. faecalis colony count was noted in all groups (P < 0.05). Maximum reduction in colony count was noted in AN/PIPS and AN/PUI groups by 91.03 and 91.29%, respectively. Minimum reduction was noted in the AN group alone. CONCLUSION: Activation with PUI and PIPS enhanced the efficacy of AgNPs irrigating solution for elimination of E. faecalis from the root canal system. CLINICAL RELEVANCE: AgNPs activated by ultrasound or PIPS can be used as an adjunct for disinfection of the root canal system in endodontic treatment.

Efficacy of titanium brush, 915 nm diode laser, citric acid for eradication of Staphylococcus aureus from implant surfaces.

BACKGROUND: This study aimed to assess the efficacy of titanium brush, 915 nm diode laser, citric acid and the combination of latter two with titanium brush for decontamination of SLA surface mini-implants. METHODS: Seventy-five mini-implants contaminated with Staphylococcus aureus (S. aureus) were randomly divided into five experimental groups (n = 12) of titanium brush (TiB), laser, citric acid (CA), brush-laser, and brush-acid, positive [n = 12; chlorhexidine mouthwash (CHX)] and negative [n = 2; phosphate buffered saline (PBS)] control groups and one no-treatment group (n = 1). After counting the colony forming units (CFUs), data were analyzed using the Kruskal-Wallis and Dunn post-hoc tests. RESULTS: Regardless of the no-treatment and negative control groups, maximum and minimum CFUs were noted in the titanium brush and positive control groups. After CHX, minimum CFUs were noted in brush-acid group followed by brush-laser, laser, and acid groups. Generally, the Kruskal-Wallis test revealed a significant difference between the groups regarding the colony count (P < 0.001). Dunn post-hoc test showed that the difference between the titanium brush and acid-brush group was significant (P < 0.001) while the differences between the brush and laser groups with the brush-laser group were not significant (P > 0.077). CONCLUSIONS: Combined use of titanium brush and citric acid yielded superior results compared to other groups in reduction of S. aureus on implant surface.

Effect of photobiomodulation on pain level during local anesthesia injection: a randomized clinical trial.

The aim of this study was to investigate the effect of photobiomodulation therapy (PBMT) as pre-treatment on pain level during injection in the anterior maxillary region. 56 Patients were randomly divided into 3 groups, Group 1:980 nm diode laser (n = 22) (experimental), Group 2:980 nm diode laser probe placed in vestibule without radiation (placebo) (n = 22), Group3: no pre-treatment before injection (n = 12) (control). Pain level during injection was evaluated by visual analog scale (VAS). The severity of pain in Group 1(experimental) and Group 2 (placebo) was significantly lower than Group 3 (control). Group 1 had a lesser pain level than Group 2, but the difference in pain level between them was not significant. PBMT with 980 nm wavelength decreased pain level during local anesthesia injection without superiority over placebo.

All done procedure by laser in free gingival graft treatment: A case series study.

AIM: This case series study evaluated the application of Er;Cr:YSGG laser for a free gingival graft procedure and the effect of low level laser therapy on post surgical pain and wound healing. CASES: 6 cases with mucogingival problems needing free gingival grafts were selected. First, the recipient site was anesthetized and de-epithelialization was done with a Er;Cr:YSGG laser. After tracing the palatal donor site with the laser, the graft was harvested. For root modification of the recipient tooth, conditioning of the dentin was done by the same laser. The inner side of graft was trimmed by the laser before suturing at the recipient site. After final adaptation of the grafts and suturing process, the recipient and donor sites were irradiated by therapeutic laser for reduction of post surgical complications. RESULTS: All patients reported the reduction in pain level after day 2 on donor and recipient site. Also, the wound healing was achieved after 14 days in all cases in donor site. CONCLUSION: According to high surface absorbance, better incision, coagulation and application on both soft and hard tissues, Er;Cr:YSGG laser can be safe, minimally invasive manner and useful for all steps of the free gingival graft procedure.

Efficacy of Photodynamic Therapy in Minimizing Bisphosphonate-Related Osteonecrosis of the Jaws After Dental Extraction: A Preliminary Animal Study.

PURPOSE: Except for a few case reports, there is no study on the efficacy of photodynamic therapy (PDT) in decreasing or preventing bisphosphonate-related osteonecrosis of the jaws (BRONJ). This preliminary animal study assessed the effectiveness of this clinical treatment. MATERIALS AND METHODS: Zoledronic acid was administered to 20 rats for 5 weeks. Two weeks later, a first molar was extracted from each rat. The rats were randomized to control and PDT groups. PDT was performed in the experimental group after surgery and at weeks 1, 2, 3, 4, 5, 6, and 7 after surgery. In the 8th week, BRONJ signs were evaluated by an observer blinded to randomization. Rats were euthanized and underwent histopathologic and histomorphometric evaluations. Clinical signs were compared using the Fisher test. Histomorphometric parameters were compared using the Mann-Whitney U test (α = 0.05). RESULTS: Two rats were lost from each group. Bone exposure decreased from 7 rats in the control group to 1 rat in the PDT group (P = .010). The stage of BRONJ decreased significantly from 7 rats in stage 1 to only 1 rat in stage 1 (P = .010). PDT decreased inflammation considerably for gingival eosinophils and lymphocytes and bone neutrophils, eosinophils, and lymphocytes. A larger percentage of live bone and smaller percentages of necrotic bone, empty lacunae, and neovascularization were observed in the PDT group. PDT also maintained bone remodeling, indicated by a large number of osteoclasts (P ≤ .001 for all comparisons by Mann-Whitney U test). CONCLUSIONS: Within the limitation of this preliminary animal study, PDT was found to be considerably effective clinically and histopathologically in decreasing or preventing BRONJ in rats. Future human studies are needed to verify these results.

Push-out bond strength of calcium-silicate cements following Er:YAG and diode laser irradiation of root dentin.

This study aimed to compare the effects of diode and Er:YAG laser irradiation of root dentin on push-out bond strength of mineral trioxide aggregate (MTA) and calcium-enriched mixture (CEM) cements. An in vitro experimental study was conducted on 90 dentin discs, cut out of freshly extracted human teeth. The discs were instrumented to obtain 1.3-mm lumen diameter. Then, they were randomly divided into six groups (n = 15). Groups 1 and 4 subjected to diode laser (Wiser, Doctor Smile, Italy) (980 nm, 1 W, continuous mode) for 10 s and filled with MTA and CEM cements. Groups 2 and 5 subjected to Er:YAG laser (Deka, Italy) (2940 nm, 1 W, 10 Hz, 230 µs) for 10 s and filled with MTA and CEM cements. Groups 3 and 6 (control groups) were filled with MTA and CEM cements without laser irradiation. After 7 days, push-out bond strength test was performed using a universal testing machine in order to evaluate the adhesion of the biomaterials to dentin. The samples were evaluated under a light microscope at × 40 magnification to determine the mode of fracture. Data were analyzed using two-way ANOVA. The highest push-out bond strength (8.76 ± 3.62 MPa) was noted in group 1 (diode/MTA), which was significantly higher than the other groups (P < 0.001). The lowest bond strength (2.61 ± 0.81) was noted in group 6 (control/CEM). Diode laser significantly increased the bond strength of both cements (P < 0.05), but Er:YAG laser irradiation only increased the bond strength of CEM and had no significant effect on MTA (P = 0.603). The bond strength of MTA control group was higher than that of CEM control group (P = 0.001). Push-out bond strength of endodontic cements can be affected by dentin conditioning with diode 980 nm and Er:YAG laser. Nine hundred eighty-nanometer diode laser irradiation is recommended to increase the bond strength of endodontic cements particularly the CEM cement to dentin.

Biofilm formation and antibiotic resistance in meticillin-resistant and meticillin-sensitive Staphylococcus aureus isolated from burns.

OBJECTIVE: To investigate the relationship between biofilm formation and antibiotic resistance patterns in meticillin-resistant and meticillin-sensitive Staphylococcus aureus, isolated from burns. METHODS: In a cross-sectional study, pus/wound swab samples were obtained from burns. Presence of Staphylococcus aureus was confirmed, and biofilm formation-related icaABCDR and eta, etb genes were detected by polymerase chain reaction. Biofilm formation assay was assessed using the microtiter plate method. Antibiotic resistance was performed using the disk diffusion method and minimum inhibitory concentration. RESULTS: A total of 95 patients with burns were recruited. Of the 95 wounds swabbed, Staphylococcus aureus was identified in 50 (62.5%), and 47 (94%) isolates capable of producing biofilm. Biofilm production levels were classed as 'strong' (n=29; 58%), 'moderate' (n=11; 22%), 'weak' (n=7; 14%) and 'non-biofilm forming' (n=3; 6%). There was an almost even split between isolates identified as meticillin-resistant Staphylococcus aureus (MRSA), n=24 (48%), and meticillin-sensitive Staphylococcus aureus (MSSA) n=26 (52%). The prevalence of the icaA, icaB, icaC, icaD and icaR genes among the studied isolates were 96%, 80%, 80%, 96% and 84%, respectively. The prevalence of eta and etb genes in isolates were 84% and 92%, respectively. CONCLUSION: Biofilm producing isolates of Staphylococcus aureus showed greater multidrug resistance than non-biofilm producers. In our study, a high rate of biofilm formation and antimicrobial drug resistance was seen. Our results highlight the alarming levels of antimicrobial resistance among MRSA strains and important data about the prevalence of eta and etb genes in Staphylococcus aureus strains isolated from burn patients in this study.

Comparative study of the effect of Er:YAG and Er:Cr;YSGG lasers on porcelain: etching for the bonding of orthodontic brackets.

This study investigated the effect of Er:YAG (smart 2940 Dplus, DEKA, Italy) and Er:CrYSGG (Waterlase iPlus, Biolase, USA) lasers on the shear bond strength (SBS) between the orthodontic brackets and dental porcelain in comparison with conventional acid etching with 9% hydrofluoric acid (HF, Ultradent, USA). A total of 60 specimens of maxillary incisor crown were prepared and randomly assigned to five groups; each group was subjected to a different porcelain surface conditioning: (1) etching with the 9% HF for 2 min; (2) etching with the 9% HF for 2 min followed by irradiation with the Er:CrYSGG laser (3-W power, 10-Hz frequency for 10 s); (3) etching with the 9% HF for 2 min followed by irradiation with the Er:YAG laser (3-W power, 10-Hz frequency for 10 s); (4) Irradiation with the Er:CrYSGG laser (3-W power, 10-Hz frequency for 10 s without acid etching) and (5) irradiation with the Er:YAG laser (3-W power,10-Hz frequency for 10 s without acid etching). After using Transbond XT primer and Transbond XT adhesive, the metal brackets (Dentaurum, Germany equilibrium 2, optimal design) bonded to the conditioned porcelain surface. Subsequently, the specimens were thermocycled for 5000 cycles and then debonded using the Universal Testing Machine (Zwick). In each group, one specimen was not bonded to brackets to allow further examination with electron microscopy. After debonding, the specimens were examined by stereomicroscope to determine their adhesive remnant index (ARI). The average SBS [Mean (SD)] values in the five groups were as follows: HF (32.58 ± 9.21 MPa), Er:CrYSGG + HF (27.81 ± 7.66 MPa), Er:YAG + HF (23.08 ± 9.55 MPa), Er:CrYSGG (14.11 ± 9.35 MPa), and Er:YAG (6.30 ± 3.09 MPa). A statistically significant difference in SBS existed between the first three groups and the two laser groups (df = 4, F = 18.555, p < 0.001). Evaluation of ARI values showed that bond failures in the first three groups were mostly of cohesive and mixed types, but in the laser groups, they were mostly adhesive. Chi-square was not significant between groups (p = 0.219). The Er:YAG laser with the stated specifications is not a suitable alternative to HF etching. In the case of Er:CrYSGG laser, although the conditioning outcome met the bond strength requirement for orthodontic brackets (that is, 6-8 MPa). Therefore, the bond strength must be further improved by fine-tuning the irradiation details.

Comparative efficacy of Er,Cr:YSGG and Er:YAG lasers for etching of composite for orthodontic bracket bonding.

Several techniques have been proposed to obtain a durable bond, and the efficacy of these techniques is assessed by measuring parameters such as bond strength. Laser has provided a bond strength as high as that of acid etching in vitro and has simpler use with shorter clinical time compared to acid etching. This study aimed to compare the efficacy of Er:YAG and Er,Cr:YSGG lasers for etching and bonding of composite to orthodontic brackets. No previous study has evaluated the effect of these particular types of laser. A total of 70 composite blocks were randomly divided into five groups (n = 14): group 1, etching with phosphoric acid for 20 s; group 2, Er:YAG laser irradiation with 2 W power for 10 s; group 3, Er:YAG laser with 3 W power for 10 s; group 4, Er,Cr:YSGG laser with 2 W power for 10 s; group 5, Er,Cr:YSGG laser with 3 W power for 10 s. Metal brackets were then bonded to composites, and after 5000 thermal cycles, they were subjected to shear bond strength test in a universal testing machine after 24 h of water storage. One sample of each group was evaluated under a scanning electron microscope (SEM) to assess changes in composite surface after etching. The adhesive remnant index (ARI) was calculated under a stereomicroscope. Data were statistically analyzed. The mean and standard deviation of shear bond strength were 18.65 ± 3.36, 19.68 ± 5.34, 21.31 ± 4.03, 17.38 ± 6.94, and 16.45 ± 4.26 MPa in groups 1-5, respectively. The ARI scores showed that the bond failure mode in all groups was mainly mixed. The groups were not significantly different in terms of shear bond strength. Er:YAG and Er,Cr:YSGG lasers with the mentioned parameters yield optimal shear bond strength and can be used as an alternative to acid etching for bracket bond to composite.

Effect of Various Laser Wavelengths on Temperature Changes During Periimplantitis Treatment: An in vitro Study.

PURPOSE: This study aimed to investigate and compare temperature change during implant decontamination with different laser types (carbon dioxide [Co2]/diode/neodymium-doped yttrium aluminum garnet [Nd:YAG]/erbium-doped yttrium aluminum garnet [Er:YAG]/antimicrobial photodynamic therapy [aPDT]). MATERIAL AND METHODS: Sixty implants were inserted into a bone block cut from a sheep's mandible. A 3 × 8 mm vertical lesion was made at the buccal of each implant. The bone block was placed into a 37°C water bath to simulate the in vivo oral condition. A K-type thermocouple was placed in contact with the implant to register temperature changes at 3 points (apical/middle/coronal). RESULTS: In the entire laser irradiations, the mean of temperature changes remains below 10°C. The apical temperature rise was higher than the coronal and middle regions (P < 0.05), and the apical temperature took longer time to reach the initial temperature (37°C) (P < 0.001). Temperature changes over 10°C occurred at the apical point of the implants with the Co2, Nd:YAG, and diode laser irradiations; however, only the Co2 laser reached the statistical significance in this regard (P < 0.05). CONCLUSION: Our findings indicate the promising results of Er:YAG laser and aPDT in implant decontamination. Precaution should be taken in the application of Nd:YAG, diode, and especially Co2 lasers.

Effect of laser-assisted bleaching with Nd:YAG and diode lasers on shear bond strength of orthodontic brackets.

The aim of the present study was to assess the effect of laser-assisted bleaching with neodymium:yttrium-aluminum-garnet (Nd:YAG) and diode lasers on shear bond strength (SBS) of orthodontic brackets. One hundred and four extracted human premolars were randomly divided into four groups: group 1: No bleaching applied (control group); group 2: Teeth bleached with 40 % hydrogen peroxide; group 3: Teeth treated with 30 % hydrogen peroxide activated with Nd:YAG laser (1064 nm, 2.5 W, 25 Hz, pulse duration of 100 µs, 6 mm distance); and group 4: Teeth treated with 30 % hydrogen peroxide activated with diode laser (810 nm, 1 W, CW, 6 mm distance). Equal numbers of teeth in groups 2, 3, and 4 were bonded at start, 1 h, 24 h, and 1 week after bleaching. A universal testing machine measured the SBS of the samples 24 h after bonding. After bracket debonding, the amount of residual adhesive on the enamel surface was observed under a stereomicroscope to determine the adhesive remnant index (ARI) scores. The SBS in the unbleached group was significantly higher than that in the bleached groups bonded immediately and 1 h after laser-assisted bleaching (P < 0.05). In groups 3 and 4 at start and group 2 at start and 1 h after laser-assisted bleaching, the SBS was found to be significantly lower than that in the control group. Significant differences in the ARI scores existed among groups as well. The SBS of brackets seems to increase quickly within an hour after laser-assisted bleaching and 24 h after conventional bleaching. Thus, this protocol can be recommended if it is necessary to bond the brackets on the same day of bleaching.

Evaluation of the effects of conventional versus laser bleaching techniques on enamel microroughness.

Nowadays, bleaching of the teeth within the dental office is one of the most widespread techniques to correct tooth discoloration. Variability of the materials and techniques accompanied with the trend toward esthetic restorations with minimally invasive approaches are increasing. The use of laser in this regard has also been taken into consideration. The aim of this study was to evaluate the effects of in-office versus laser bleaching on surface roughness of enamel. Fifteen freshly extracted human molars were sectioned mesiodistally to produce 30 lingual and buccal enamel blocks. Samples were mounted in transparent acrylic resin blocks and polished before treatment. Samples were randomly assigned to laser bleaching (LB) and office bleaching (OB) groups (n = 15 each). Pretreatment evaluation of microroughness was carried out for all samples using profilometer. Samples were treated twice in the OB group with Opalescent Xtra Boost and in the LB group using a laser-activated gel. Microroughness was evaluated after bleaching in both groups. Data were analyzed using repeated measure ANOVA. Both methods increased enamel surface roughness. Microroughness changes were significantly different between the two groups (p < 0.05). Microroughness significantly increased in the OB group (p > 0.05), but there was no significant difference in pre- and post-treatment roughness evaluation in the LB group (p < 0.05). Laser was considered a safer technique because it demonstrated a less surface roughness increase in comparison with the conventional office bleaching procedure.