The impact of photobiomodulation on angiogenic differentiation of two different dental derived stem cells using two irradiation protocols: an in vitro investigation.

The present study aimed to compare the effect of photobiomodulation with different energy densities on the angiogenic differentiation of human periodontal ligament stem cells (hPDLSCs) and stem cells from human exfoliated deciduous teeth (SHED). Photobiomodulation therapy with a 660 nm diode laser (2.4 J/cm2 and 3.9 J/cm2) on two consecutive days post-culture was applied to two types of stem cells (hPDLSCs and SHED). The Quantitative Real-time Polymerase Chain Reaction (RT-qPCR) test was undertaken to investigate Vascular Endothelial Growth Factor-A (VEGF-A) and Angiopoietin I (ANG-I) genes on days 1, 3, 5, 7, and 10 after the first session of laser application. The 4',6-diamidino-2-phenylindole (DAPI) staining and Methyl Thiazolyl Tetrazolium (MTT) test were conducted on days 1, 3, and 5 after the first session of laser application, to assess the cell viability. The Two-way ANOVA with Tukey post hoc test was used to analyze the outcomes of the MTT and RT-qPCR tests. The results of the MTT and DAPI convergently illustrated that the groups receiving photobiomodulation with 2.4 J/cm2 had higher cell viability compared to 3.9 J/cm2. All experimental groups showed an upregulation of VEGF-A and ANG-I gene expression from day 1 to 5, followed by a downregulation from day 5 to 10. The groups with cultured hPDLSCs and SHED receiving photobiomodulation using 2.4 J/cm2 had the most amounts of VEGF-A and ANG-I gene expression on day 5, respectively. In conclusion, the 660 nm mediated photobiomodulation therapy of cultured SHED and hPDLSCs with 2.4 J/cm2 energy density may be associated with higher angiogenic differentiation (the expression of VEGF-A and ANG-I) as well as higher cell viability compared to the photobiomodulation therapy with 3.9 J/cm2.

Detection of Residual Excess Zinc Oxide-Based Cement With Laser Fluorescence (DIAGNOdent): In Vitro Evaluation.

Because of its importance in the development of peri-implant mucositis and peri-implantitis, detection of residual excess cement (REC) is often the focus of studies addressing cement-retained implant-supported restorations. The purpose of this study was to evaluate the sensitivity and specificity of laser fluorescence (DIAGNOdent) for detecting residual excess zinc oxidebased cement around dental implants. In this in vitro study, 15 tissue-level implants were embedded in acrylic resin. To simulate gingiva around the implants, the transgingival part of each implant was covered with a gingival mask silicon material. Cement (Tempobond; 1 × 1 × 1 mm) was applied to 30 areas, 4 mm below the gingival-mimicking line using a custom-made template. A DIAGNOdent laser device was used by 2 independent examiners to evaluate the presence or absence of cement in a selected area. The examiners were allowed to probe the gingival sulcus (2-mm depth) 2 times with a 5-minute interval between tests. The residual cement was recognized by gently walking the device tip around the implant. A detection score less than 16 indicated an absence of cement, and scores of 16 or greater indicated the presence of excess luting agent in the implant sulcus. The sensitivity and specificity of DIAGNOdent to detect REC in the sulcus were 100% and 96.67%, respectively. Based on our findings, we propose that DIAGNOdent could be used to detect REC in the sulcus of cement-retained implant supported restorations.

Evaluating the effect of photobiomodulation with a 940-nm diode laser on post-operative pain in periodontal flap surgery.

The aim of this study was to evaluate the efficacy of low-power of 940-nm diode laser on post-operative pain after undisplaced flap surgery. This randomized clinical trial study was conducted using a split-mouth design. The study participants comprised 30 patients who needed periodontal flap surgery for periodontal pockets on the same tooth on both sides of the mandible. One side of the mandible was subjected to undisplaced flap surgery plus treatment with a 940-nm diode laser, and on the contralateral side, the surgery was conducted without applying the laser. Patients received anti-inflammatory medication and analgesics after surgery. The patients were asked to report the number of analgesics they took and the pain they experienced each night for 1 week using a visual analogue scale. An independent-sample t test was used to compare the results between the two groups. Patients reported less pain on days 2, 3, 4, 5, 6, and 7 after surgery in the laser-treated group (p < 0.05). Furthermore, fewer analgesics were used in this group on days 3, 4, 5, 6, and 7 following the surgery (p < 0.05). The 940-nm diode laser with the settings used in this study could significantly reduce pain and the number of analgesics taken by patients after undisplaced flap surgery.

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.

Evaluating osteogenic potential of a 3D-printed bioceramic-based scaffold for critical-sized defect treatment: an in vivo and in vitro investigation.

The integration of precision medicine principles into bone tissue engineering has ignited a wave of research focused on customizing intricate scaffolds through advanced 3D printing techniques. Bioceramics, known for their exceptional biocompatibility and osteoconductivity, have emerged as a promising material in this field. This article aims to evaluate the regenerative capabilities of a composite scaffold composed of 3D-printed gelatin combined with hydroxyapatite/tricalcium phosphate bioceramics (G/HA/TCP), incorporating human dental pulp-derived stem cells (hDPSCs). Using 3D powder printing, we created cross-shaped biphasic calcium phosphate scaffolds with a gelatin layer. The bone-regenerating potential of these scaffolds, along with hDPSCs, was assessed through in vitro analyses and in vivo studies with 60 rats and critical-sized calvarial defects. The assessment included analyzing cellular proliferation, differentiation, and alkaline phosphatase activity (ALP), and concluded with a detailed histological evaluation of bone regeneration. Our study revealed a highly favorable scenario, displaying not only desirable cellular attachment and proliferation on the scaffolds but also a notable enhancement in the ALP activity of hDPSCs, underscoring their pivotal role in bone regeneration. However, the histological examination of calvarial defects at the 12-wk mark yielded a rather modest level of bone regeneration across all experimental groups. The test and cell group exhibited significant bone formation compared to all other groups except the control and cell group. This underscores the complexity of the regenerative process and paves the way for further in-depth investigations aimed at improving the potential of the composite scaffolds.

Bilayer scaffolds/membranes for bone tissue engineering applications: A systematic review.

OBJECTIVE: This systematic review evaluates the purpose, materials, physio-mechanical, and biological effects of bilayer scaffolds/membranes used for bone tissue engineering applications. METHODS: A comprehensive electronic search of English-language literature from 2012 to October 2022 was conducted in PubMed, Scopus, ScienceDirect, and Google Scholar online databases according to the PRISMA 2020 guidelines. The quality of animal studies was evaluated through the SYRCLE's risk of bias tool. RESULTS: A total of 77 studies were sought for retrieval, and 39 studies met the inclusion criteria. According to the synthesis results, most bilayers had a dense barrier layer that prevented connective tissue penetration and a loose osteogenic layer that supported cell migration and osteogenesis. PLGA, PCL, and chitosan were the most common polymers in the barrier layers, while the most utilized polymers in osteogenic layers were PLGA and gelatin. Electrospinning and solvent casting were the most common fabrication methods to design the bilayer structures. Many studies reported higher biological results for bilayers compared to their single layers. Also, fabricated bilayers' in vitro osteogenesis and in vivo new bone formation were significantly superior or at least comparable to the frequently used commercial membranes. CONCLUSION: 1) Bilayers with two distinct layers and different materials, porosities, mechanical properties, and biological behavior can significantly improve heterogeneous bone regeneration; 2) the addition of ceramics and/or drugs to the osteogenic layer enhances the osteogenic properties of the bilayers; 3) fabrication method and pore size of the layers play an important role in determining the mechanical and biological behavior of them.

Periosteum as a covering vascular flap in posterior mandibular augmentation: A retrospective cohort study.

OBJECTIVE: To analyze the impact of creating periosteal vascular flaps on the amount of bone augmentation following inlay bone grafting (IBG) and cortical autogenous tenting (CAT). MATERIALS AND METHODS: This was a retrospective cohort study enrolling a sample cohort of patients presented to a private clinic in 2015 and 2019 for posterior mandibular ridge augmentation before dental implant placement. The predictor variables were surgical methods: CAT vs. CAT in conjunction with periosteal flap (CATP) vs. IBG vs. IBG in conjunction with periosteal flap (IBGP). The primary outcome variables were supra bundle bone (SBB) superior to the inferior alveolar canal (ΔH) and crestal width difference (ΔW) at a 4-month follow-up. Appropriate statistics were computed at 0.05 significance level. RESULTS: A total of 29 cases (10 males and 19 females) with a mean age of 57.96±7.14 years were included. A total of 33 sites were augmented through CATP, 16 sites through IBGP, 33 sites through CAT, and 11 sites through IBG techniques. All patients healed uneventfully without permanent neurosensory changes, and adequate horizontal (ΔW:3.33±0.71 mm) and vertical (ΔH:5.10±2.04 mm) bone dimensions were restored that allowed implant placement. Using periosteal vascular flaps significantly increased bone augmentation in both vertical and horizontal dimensions (P < 0.01). CONCLUSION: Periosteal vascular flaps can increase the efficacy of mandibular augmentation techniques and decrease post-surgical complications.

Comparative Biocompatibility and Odonto-/Osteogenesis Effects of Hydraulic Calcium Silicate-Based Cements in Simulated Direct and Indirect Approaches for Regenerative Endodontic Treatments: A Systematic Review.

BACKGROUND: Regenerative dentistry is the operation of restoring dental, oral and maxillofacial tissues. Currently, there are no guidelines for the ideal cement/material in regenerative endodontic treatments (RET). Hydraulic calcium silicate-based cements (hCSCs) are currently the material of choice for RET. OBJECTIVES: This systematic review was conducted to gather all of the different direct and indirect approaches of using hCSCs in RET in vitro and in vivo, and to ascertain if there are any superiorities to indirect approaches. METHODS AND MATERIALS: This systematic review was conducted according to the 2020 PRISMA guidelines. The study question according to the PICO format was as follows: Comparison of the biological behavior (O) of stem cells (P) exposed to hCSCs through direct and indirect methods (I) with untreated stem cells (C). An electronic search was executed in Scopus, Google Scholar, and PubMed. RESULTS: A total of 78 studies were included. Studies were published between 2010 and 2022. Twenty-eight commercially available and eighteen modified hCSCs were used. Seven exposure methods (four direct and three indirect contacts) were assessed. ProRoot MTA and Biodentine were the most used hCSCs and had the most desirable results. hCSCs were either freshly mixed or set before application. Most studies allowed hCSCs to set in incubation for 24 h before application, which resulted in the most desirable biological outcomes. Freshly mixed hCSCs had the worst outcomes. Indirect methods had significantly better viability/proliferation and odonto-/osteogenesis outcomes. CONCLUSION: Biodentine and ProRoot MTA used in indirect exposure methods result in desirable biological outcomes.

Application of biodegradable Patient-specific scaffolds for maxillofacial bone regeneration: a scoping review of clinical studies.

This study aimed to systematically review clinical studies in which biodegradable patient-specific scaffolds were used for bone regeneration. Studies in which biodegradable scaffolds were fabricated through computer-assisted design and computer-assisted manufacturing (CAD-CAM) procedures were included. Those that applied non-biodegradable materials or used biodegradable materials in a condensable powder or block form were excluded. Among a total of 26 included studies, 11 used customised allogeneic bone blocks, five used polycaprolactone (PCL)-containing scaffolds, four used hydroxyapatite (HA) scaffolds, and four biphasic calcium phosphate (BCP). The majority of the studies applied scaffolds for minor intraoral defects. All the large defects were reconstructed with polymer-containing scaffolds. Results of the included studies showed partial to complete filling of the defect following the application of biodegradable scaffolds. However, limited graft exposure was reported when using PCL, BCP, and HA scaffolds. Tissue engineering can be considered a potential method for the treatment of maxillofacial bone defects. However, more evidence is required, especially for the application of biodegradable scaffolds in large defects.

The effect of antibacterial photodynamic therapy with diode laser on chromogenic bacteria associated with dental black staining: An in-vitro study.

BACKGROUND: Aggregatibacter actinomycetemcomitan (A.a) and Actinomyces naeslundii (A.n) are two gram-negative chromogenic bacteria involved in the formation of dental black stainings. Our study aimed to investigate the antibacterial effect of photodynamic therapy (aPDT) using two photosensitizers, Methylene Blue (MB) and Indocyanine Green (ICG). MATERIALS AND METHODS: In this in-vitro study, two isolates of each selected bacterium were cultured and treated as follows; Negative control with no treatment; CHX as a positive control; ICG; MB; ICG with 808 nm laser activation; and MB with 660 nm laser activation. The number of colonies (CFU/mL) was determined to compare the groups. The qualitative evaluation of biofilm formation was done by scanning electron microscopy of treated enamel pieces. The logarithmic values of the colony counts were compared using One-way ANOVA and the Welch test Tukey HSD and Games-Howell tests were used for multiple comparisons. P-values of less than 0.05 were considered statistically significant. RESULTS: The use of ICG alone or along with laser irradiation at the wavelength of 808 nm significantly reduced the number of colonies of A.a and A.n bacteria. Comparing the colony counts in the MB group with the positive control showed no significant decrease in bacterial load. On the contrary, activation of MB with 660 nm radiation of diode laser showed a significant antibacterial effect. The density of bacterial biofilm was significantly lower in the groups treated with MB and ICG without laser activation than in the control group; however, the reduction in bacteria biofilm density was more robust using photodynamic therapy with ICG. CONCLUSION: aPDT using MB with 660 nm laser and ICG with 808 nm laser significantly reduced the number of chromogenic A.a and A.n bacteria, and photodynamic therapy with ICG was proven to be significantly more effective than MB with or without laser radiation.

3D-printed MgO nanoparticle loaded polycaprolactone ß-tricalcium phosphate composite scaffold for bone tissue engineering applications: In-vitro and in-vivo evaluation.

Magnesium (Mg) plays an important role in controlling bone apatite structure and density and is a potential bioactive material in repairing critical-sized bone defects. In this study, we aimed to evaluate the effect of adding NanoMgO to polycaprolactone/beta-tricalcium phosphate (PCL/ß-TCP) scaffolds on bone regeneration. Novel 3D-printed porous PCL/ß-TCP composite scaffolds containing 10% nanoMgO were fabricated by fused deposition modeling (FDM) and compared with PCL/ß-TCP (1:1) scaffolds (control). The morphology and physicochemical properties of the scaffolds were characterized by ATR-FTIR, XRD, scanning electron microscope-energy dispersive X-ray analysis (SEM-EDX), transmission-electron-microscopy (TEM), water contact angle, and compressive strength tests and correlated to its cytocompatibility and osteogenic capacity in-vitro. To evaluate in-vivo osteogenic capacity, bone-marrow-derived stem cell (BMSC)-loaded scaffolds were implanted into 8 mm rat critical-sized calvarial defects for 12 weeks. The hydrophilic scaffolds showed 50% porosity (pore size = 504 µm). MgO nanoparticles (91.5 ± 27.6 nm) were homogenously dispersed and did not adversely affect BMSCs' viability and differentiation. Magnesium significantly increased elastic modulus, pH, and degradation. New bone formation (NBF) in Micro-CT was 30.16 ± 0.31% and 23.56 ± 1.76% in PCL/ß-TCP/nanoMgO scaffolds with and without BMSCs respectively, and 19.38 ± 2.15% and 15.75 ± 2.24% in PCL/ß-TCP scaffolds with and without BMSCs respectively. Angiogenesis was least remarkable in PCL/ß-TCP compared with other groups (p < .05). Our results suggest that the PCL/ß-TCP/nanoMgO scaffold is a more suitable bone substitute compared to PCL/ß-TCP in critical-sized calvarial defects.

Evaluating the Preemptive Analgesic Effect of Photo-biomodulation Therapy on Pain Perception During Local Anesthesia Injection in Children: A Split-mouth Triple-blind Randomized Controlled Clinical Trial.

To evaluate the impact of photobiomodulation therapy (PBMT) on injection pain perception and compare it with a topical oral anesthetic gel. A total of 30 patients of 6 to 9 years-old seeking pulpotomy treatment of maxillary secondary primary molars of both sides were considered for this split-mouth triple-blind randomized clinical trial. On one side of the maxilla, the low-level laser (diode laser, 808 nm, 250 mW; 16.25 J; 32.5 J cm-2 ) was irradiated upon the buccal gingiva of the tooth, while a Benzocaine 20% topical anesthetic gel was applied on the other side. A gel with the same taste (strawberry) was applied for the placebo. The Wong-Baker Faces Pain Rating Scale was used to evaluate the injection pain and postoperation pain at two timestamps, 1 h and 24 h after treatment. Patients' heart rate was also evaluated. Paired t, Wilcoxon signed-rank test, McNemar and Friedman tests were used for statistical analyses. Results demonstrated that PBMT could significantly decrease the injection pain perception and heart rate alternations compared to the topical anesthetic gels (P = 0.000). However, no significant differences were documented between the two methods concerning the 1-h (P = 0.26) and 24-h (P = 1.00) postoperation pain. PBMT can be an effective nonpharmacological technique for controlling injection pain.

Current Trends, Advances, and Challenges of Tissue Engineering-Based Approaches of Tooth Regeneration: A Review of The Literature.

INTRODUCTION: Tooth loss is a significant health issue. Currently, this situation is often treated with the use of synthetic materials such as implants and prostheses. However, these treatment modalities do not fully meet patients' biological and mechanical needs and have limited longevity. Regenerative medicine focuses on the restoration of patients' natural tissues via tissue engineering techniques instead of rehabilitating with artificial appliances. Therefore, a tissue-engineered tooth regeneration strategy seems like a promising option to treat tooth loss. OBJECTIVE: This review aims to demonstrate recent advances in tooth regeneration strategies and discoveries about underlying mechanisms and pathways of tooth formation. RESULTS AND DISCUSSION: Whole tooth regeneration, tooth root formation, and dentin-pulp organoid generation have been achieved by using different seed cells and various materials for scaffold production. Bioactive agents are critical elements for the induction of cells into odontoblast or ameloblast lineage. Some substantial pathways enrolled in tooth development have been figured out, helping researchers design their experiments more effectively and aligned with the natural process of tooth formation. CONCLUSION: According to current knowledge, tooth regeneration is possible in case of proper selection of stem cells, appropriate design and manufacturing of a biocompatible scaffold, and meticulous application of bioactive agents for odontogenic induction. Understanding innate odontogenesis pathways play a crucial role in accurately planning regenerative therapeutic interventions in order to reproduce teeth.

Prefabrication technique by preserving a muscular pedicle from masseter muscle as an in vivo bioreactor for reconstruction of mandibular critical-sized bone defects in canine models.

In vivo bioreactors serve as regenerative niches that improve vascularization and regeneration of bone grafts. This study has evaluated the masseter muscle as a natural bioreactor for ßTCP or PCL/ßTCP scaffolds, in terms of bone regeneration. The effect of pedicle preservation, along with sole, or MSC- or rhBMP2-combined application of scaffolds, has also been studied. Twenty-four mongrel dogs were randomly placed in six groups, including ßTCP, ßTCP/rhBMP2, ßTCP/MSCs, PCL/ßTCP, PCL/ßTCP/rhBMP2, and PCL/ßTCP/MSCs. During the first surgery, the scaffolds were implanted into the masseter muscle for being prefabricated. After 2 months, each group was divided into two subgroups prior to mandibular bone defect reconstruction; one with a preserved vascularized pedicle and one without. After 12 weeks, animals were euthanized, and new bone formation was evaluated using histological analysis. Histological analysis showed that all ß-TCP scaffold groups had resulted in significantly greater rates of new bone formation, either with a pedicle surgical approach or non-pedicle surgical approach, comparing to their parallel groups of ßTCP/PCL scaffolds (p ≤ .05). Pedicled ß-TCP scaffold groups that were treated with either rhBMP2 (48.443% ± 0.250%) or MSCs (46.577% ± 0.601%) demonstrated the highest rates of new bone formation (p ≤ .05). Therefore, masseter muscle can be used as a local in vivo bioreactor with potential clinical advantages in reconstruction of human mandibular defects. In addition, scaffold composition, pedicle preservation, and treatment with MSCs or rhBMP2, influence new bone formation and scaffold degradation rates in the prefabrication technique.

Comparative evaluation of the effects of three hydraulic calcium silicate cements on odontoblastic differentiation of human dental pulp stem cells: an in vitro study.

OBJECTIVE: The study aimed to compare the response of human dental pulp stem cells (hDPSCs) towards three hydraulic calcium silicate cements (HCSCs) by measuring cytotoxicity and expression of dentinogenic genes. METHODOLOGY: Dental pulps of five impacted mandibular third molars were extirpated as a source for hDPSCs. Next to culturing, hDPSCs were subjected to fluorescence-activated cell sorting after the third passage to validate stemness of the cells. Human DPSCs were exposed to diluted supernatants of OrthoMTA (OMTA), Biodentine (BD) and Calcium-Enriched Mixture (CEM) at concentrations 10, 25, 50 and 100% at the first, third and fifth day of culture. Then, cells were exposed to 10% concentrations supernatant of HCSCs to determine DSPP and DMP1 gene expression, using a quantitative polymerase-chain reaction. Data were analyzed using one-way and three-way ANOVA, followed by Tukey post hoc statistical tests. RESULTS: Optimal cell proliferation was observed in all groups, regardless of concentration and time-point. HCSC supernatants were non-cytotoxic to hDPSCs at all three time-points, except for 100% Biodentine on day five. On day seven, OMTA group significantly upregulated the expression of DSPP and DMP1 genes. On day 14, expression of DMP1 and DSPP genes were significantly higher in BD and OMTA groups, respectively. CONCLUSION: Biodentine significantly upregulated DMP1 gene expression over 14 days, whereas CEM was associated with only minimal expression of DSPP and DMP1 .

Effect of Photobiomodulation on Relapse in an Experimental Rapid Maxillary Expansion Model in Rat.

Rapid maxillary expansion (RME) is performed on transversely deficient maxilla. As all orthodontic treatments, retention is important in maintaining therapeutic outcomes. Fixed /removable retainers are used post-RME causing hygiene and compliance problems. Given photobiomodulation's positive effects on the quantity and quality of bone regeneration, its effect on post-RME relapse was studied. Thirty Sprague Dawley rats were randomly divided into group R, non-irradiated RME-treated (n = 12), group P, irradiated RME-treated (n = 12) and group C, non-RME non-irradiated (n = 6). A 1.5 mm metal ring inserted between maxillary incisors at days 0 and 15 was expanded until 1.5 mm space was obtained at day 30. In group P, Ga-Al-As diode laser (810 nm, 100 mW, 4J/cm2 , 30 secs) was applied on days 0, 2, 4, 6, 8, 10, 12 and 14 as predictor variable. The relapse was measured as the space lost between incisors for 30 days after appliance removal (primary outcome variable) and compared with t-test. In week 2, space loss in group P was significantly lower (P < 0.05) than all other groups. The relapse during weeks 2 and 3 was significantly lower in group P than group R. However, no significant difference in relapse amount was found between groups during first and fourth week. There was a significant difference (P < 0.05) between groups in relapse rates (secondary outcome variable) but not in total relapse after 4 weeks. Photobiomodulation proved beneficial in resisting relapse in our study, and it is suggested to be continued until the end of expansion.

Laser Aided Ceramic Restoration Removal: A Comprehensive Review.

Introduction: All-ceramic restorations are being widely used due to its various advantages. However, they have restricted durability and may have to be removed. The conventional procedure for removal is grinding the restoration with rotary instruments which are considered time-consuming and inconvenient. A newer advantageous method is the application of lasers for debonding ceramics from the tooth surface. The objective of this study is to provide a comprehensive literature review on laser-aided ceramic restorations debonding. Methods: We searched PubMed and Google Scholar databases. Seven articles from 2011 to 2018 were identified. Studies were assessed for the efficacy of laser application and the amount of pulpal temperature rise. Results: Studies selected were categorized according to variables including shear bond strength, debonding time and intrapulpal temperature. Oztoprak and Iseri investigated that erbium-doped yttrium, aluminum, and garnet (Er:YAG) laser application reduced shear bond strength of ceramic laminate veneers. The time of debonding took an average of 190 seconds in Rechmann's study and 106 seconds in Morford's study. One of the main issues while using the laser is thermal irritation of the pulp. A 5.5°C temperature increase may cause pulpal damage according to Zach and Cohen. Philips et al and Rechmann et al reported no intrapulpal harm due to temperature increase. Additionally, Phillips et al demonstrated that the laser setting affects both the debonding time and the temperature alterations and that a laser adjustment of 2.5 W/25 Hz would be the best safest group. Conclusion: Removal of ceramic crowns and veneers from tooth surfaces can be successfully done by Er:YAG laser application in a less time-consuming procedure and without any harm to the underlying dentin. However, a temperature rise in the pulp may occur which could be overcome by adequate air water cooling.

Comparison of Tooth Color Change After Bleaching With Conventional and Different Light-Activated Methods.

Introduction: The demand for esthetic dental treatments is increasing in recent years mainly due to improved oral hygiene and better maintenance of oral health and teeth in older individuals. Bleaching of discolored anterior teeth is the most popular among esthetic dental treatments. Even individuals with sound teeth and adequate esthetics seek to have whiter teeth in the anterior region. The aim of this study was to evaluate tooth color changes following conventional in-office bleaching techniques compared to light-activated methods using different light sources. Methods: Seventy sound anterior teeth (devoided of caries and/or fracture), extracted for periodontal and orthodontic reasons were selected and allocated to 7 groups: (A) control, (B) conventional bleaching (C) LED-activated bleaching, (D) KTP laser-activated bleaching, (E) diode laser-activated bleaching, (F) Nd:YAG laser-activated bleaching and (G) CO2 laser-activated bleaching. Colorimetric evaluation was carried out before and after treatment using a spectrophotoradiometer. Data were analyzed by one- and two-way analysis of variance (ANOVA) as well as multiple comparison methods. Results: The results showed that all bleaching procedures were effective in reducing the yellowness index. However, the KTP laser-activated bleaching was significantly more effective than the other techniques in 95% confidence level. It was also seen that CO2 laser activated method has outperformed groups E, F and G and the conventional bleaching without light activation was not effective at all and represented similar results with the control group. Furthermore, the groups E and G had almost the same results in decreasing the yellowness index. Conclusion: The results showed that all bleaching techniques were effective however, the KTP laser-activated bleaching was significantly more efficient, closely followed by the CO2 laser-activated bleaching technique.

Effect of laser photobiomodulation on wound healing and postoperative pain following free gingival graft: A split-mouth triple-blind randomized controlled clinical trial.

BACKGROUND AND AIM: Free gingival graft (FGG) is one of the most predictable techniques for gingival augmentation. However, patient's discomfort and pain during healing period are significant concerns. The aim of this study was to assess if laser photobiomodulation (PBM) was effective in terms of enhancing wound healing and reducing postoperative pain. METHODS AND MATERIALS: Twelve patients participated in this split-mouth randomized controlled clinical trial. Each patient had a 30-day interval between the two procedures. In the test group, donor and recipient sites received diode laser (660nm, 200mW, continuous mode, time of irradiation:32s, energy density: 4J/cm2, spot size:0.5cm) immediately after FGG surgery, and 1,2,4 and 7days later. The control side received the same sequence of irradiation with the laser-off. Complete wound epithelialization of donor site and clinical wound healing and visual analogue scale (VAS) pain score of donor and recipient sites were evaluated after surgery. RESULTS: At 14 and 21days after surgery, the number of donor sites with complete epithelialization was greater in laser group compared to the placebo. After 21days, all donor sites in the test group were epithelialized completely, while at the same time, only eight donor sites in the control group showed complete epithelialization (P value=0.05). In terms of clinical healing of the recipient and donor sites, the test and control groups did not show any significant difference during the 45-day period, except at days 1 (for recipient site) and 14 (for donor site), when the test group showed better results (P values: 0.01 and 0.03, respectively). The VAS pain score did not show statistically significant difference between two groups during the study period, except for the first 3h after procedure when laser group showed greater VAS pain score (P values<0.05). CONCLUSION: PBM following FGG procedure with the parameters used in this study could accelerate the rate of epithelialization at the donor site. However, it did not reduce postoperative pain.

Comparing fibroblast attachment in root surface scaling with Er, Cr:YSGG laser versus ultrasonic scaler: A SEM study.

BACKGROUND AND OBJECTIVES: The regeneration of periodontal support is the main concern in periodontal therapy. The aim of this in vitro study was to investigate the fibroblasts attachment on root surfaces after scaling with Er, Cr:YSGG laser and ultrasonic instruments using scanning electron microscopy (SEM). METHODS: 72 root plates of ∼6 × 4 × 1 mm3 in dimension were prepared from 27 single-rooted human mature teeth and were then divided into four groups. One group irradiated with a G6 tip of Er, Cr:YSGG laser (2.78 µm, 0.75 W, pulse duration of 140 µs, repetition rate of 20 Hz) for 5 to 7 s, and the other groups were scaled with ultrasonic alone or laser-ultrasonic. The control group was subjected to neither laser nor ultrasonic scaling. Subsequently, Viability and proliferation rates were done using MTT assay on days 3 and 5. Finally the cell attachment was observed using SEM. RESULTS: The data derived from MTT and cell-attachment analysis indicated that laser-ultrasonic scaling tended to increase cell-viability by the lapse of time (within 3-5 days), with significantly better cell-attachment compared with other groups on days 3 and 5 (p < .05). The comparison of the difference in fibroblast cell attachment rate on both the third and the fifth day with independent T-Test indicated a significant rise on the fifth day compared to the third day of study (p < .05). CONCLUSION: Indeed, both Er, Cr:YSGG laser and ultrasonic scaling may promote fibroblast attachment on dentinal root surfaces more than laser or ultrasonic scaling alone.