Skeletal maturation evaluation: which is the reliability of dental calcification Demirjian method versus hand-wrist X-ray in growing subjects? A systematic review.

OBJECTIVES: This systematic review aimed at evaluating the reliability of dental maturation (DM) according to Demirjian method compared to hand and wrist maturation (HWM) to assess skeletal maturity (SM) in growing subjects, to identify the teeth and the corresponding mineralisation stages related to the pubertal growth spurt (PGS). MATERIALS AND METHODS: PubMed, Scopus, and Web of Science were systematically searched until January 5th, 2024, to identify observational cross-sectional studies that assessed the reliability of Demirjian method compared to the HWM methods (i.e., Grave and Brown and Fishman) in growing subjects. The quality assessment was evaluated using the Joanna Briggs Institute (JBI) Critical Appraisal Checklist. RESULTS: Out of 136 papers suitable for title/abstract screening, 19 included studies. Of them, 17 papers showed the reliability of Demirjian DM method compared to HWM Fishman and Grave and Brown methods to assess SM in growing subjects. According to JBI Critical Appraisal Checklist, 12 papers were high-quality studies and 7 papers were medium-quality studies.  Conclusions: The mandibular second molar might be considered as the best indicator compared to other teeth and that the peak of growth occurs no earlier than stage F in females and stage G in males according to Demirjian method. Also, the mandibular canine might be analysed as indicator of SM in males, and results suggest that the peak of growth occurs no earlier than maturation stage F according to Demirjian method, only in male subjects. Further studies are needed to confirm these findings.

Efficacy of a new protocol for the prevention of work-related musculoskeletal disorders in dental hygiene students: A pilot randomized controlled trial.

OBJECTIVE: The purpose of this pilot randomized controlled trial (RCT) was to assess the efficacy of a new muscle stretching and strengthening protocol for the prevention of work-related musculoskeletal disorders (WMSD) in dental hygiene students. METHODS: Students attending the 2nd and 3rd year of a Dental Hygiene Degree Course of a University Hospital were randomly allocated into treatment group (muscle stretching and strengthening sessions) and control group (no treatment). Nordic Musculoskeletal Questionnaire (NMQ), quality of life, the intensity of the pain and the Global Perceived Effect (GPE) Scale were assessed at the baseline (T0), after 4 weeks (T1) and after 16 weeks (T2). RESULTS: Of 37 subjects screened for eligibility, 28 patients (aged 28.25 ± 8.89 years) were enrolled and divided into treatment and control groups. The NWQ showed significant between-group differences in the following regions from T0 to T2: neck (p = 0.0003), shoulders (p = 0.0057) and lower back (p = 0.0136). In terms of pain, a significant between-group difference was reported from T2 (p < 0.001). The GPE demonstrated that the average satisfaction related to the performed treatment was 1.4 ± 0.63. CONCLUSION: The present pilot RCT demonstrated the efficacy of stretching associated with muscle strengthening in decreasing the risk of WMSD, especially for the neck, shoulders and lower back. The potential strength of this model is related to the possibility to perform stretching exercises chairside at work during scheduled breaks, in addition to complementary muscle strengthening sessions at home. Future RCTs are necessary to better investigate the role of this protocol for WMSD prevention.

Temporomandibular disorders and neck pain in primary headache patients: a retrospective machine learning study.

OBJECTIVES: To evaluate the linkage underpinning different clinical conditions as painful TMD and neck pain in patients affected by primary headaches. MATERIALS AND METHODS: In this machine learning study, data from medical records of patients with headaches as migraine, tension-type headache (TTH) and other primary ones, referring to a University Hospital over a 10-year period were analysed. VAS was used to evaluate the intensity of the TMD and neck pain. Moreover, the magnetic resonance imaging was used to supplement the clinical data. RESULTS: A total of 300 patients (72 male, 228 female), mean aged 37.78 ± 5.11 years, were included. Higher TMD and neck pain VAS in migraine patients were reported. The machine learning analysis focussed on type of primary headache demonstrated that a higher TMD VAS was correlated to migraine, whereas a higher neck pain VAS was correlated to TTH or migraine. Concerning the TMD type, arthrogenous and mixed TMD were correlated to mild-moderate TMD pain (depending on neck pain intensity), whereas myogenic TMD was correlated to moderate-severe TMD pain. CONCLUSIONS: Machine-learning approach highlighted the complexity of diagnosis process and demonstrated that neck pain might be an influential variable on the belonging to different group of headaches in TMD patients.

Oral-Gut Microbiota, Periodontal Diseases, and Arthritis: Literature Overview on the Role of Probiotics.

Periodontal diseases are oral inflammatory diseases affecting the tissues supporting and surrounding the teeth and include gingivitis and periodontitis. Oral pathogens may lead to microbial products spreading into the systemic circulation and reaching distant organs, while periodontal diseases have been related to low-grade systemic inflammation. Gut and oral microbiota alterations might play a role in the pathogenesis of several autoimmune and inflammatory diseases including arthritis, considering the role of the gut-joint axis in the regulation of molecular pathways involved in the pathogenesis of these conditions. In this scenario, it is hypothesized that probiotics might contribute to the oral and intestinal micro-ecological balance and could reduce low-grade inflammation typical of periodontal diseases and arthritis. This literature overview aims to summarize state-of-the-art ideas about linkages among oral-gut microbiota, periodontal diseases, and arthritis, while investigating the role of probiotics as a potential therapeutic intervention for the management of both oral diseases and musculoskeletal disorders.

Aging hampers neutrophil extracellular traps (NETs) efficacy.

BACKGROUND: NETosis is a neutrophil-mediated defense mechanism during which DNA and enzymes are extruded forming a network (NETs) trapping and killing different pathogens. NETosis is reduced in both mice and humans during aging. AIMS: We explored the difference in the efficacy of NETs released in elderly (> 65 years) versus adults (20-50 years) subjects in inhibiting Staphylococcus aureus growth and activating the growth of keratinocytes. METHODS: Neutrophil granulocytes, obtained from venous blood both in healthy elderly and adult subjects, were stimulated by LPS (0-250 µg/ml) to induce the formation of NET. NETs were quantified by SYBR Green staining and growth inhibition of S. aureus was evaluated by disk diffusion test. Furthermore, NETs (0-500 ng/ml) were added to immortalized human keratinocytes (HaCaT cells), and their proliferation was evaluated by MTT assay after 24 h. Finally, the DNA size of NETs was evaluated by flow cytometry after SYBR Green staining. RESULTS: Greater production of NETs was observed in elderly subjects than in adults, but these NETs showed reduced bactericidal capacity and HaCaT cells' proliferation stimulation. The activities of the NETs are related to the size of the extruded DNA threads, and when NETs size was analyzed, DNA from elderly showed a higher size compared to that obtained by adults. DISCUSSION: Unexpected results showed aging-related NETs structural modification resulting in both a lower antimicrobial activity and keratinocyte proliferation stimulation compared to NETs obtained from adults. CONCLUSIONS: The NETs DNA size observed in elderly subjects has not been previously reported and could be part of other pathogenic mechanisms observed in aging.

Photobiomodulation induces microvesicle release in human keratinocytes: PI3 kinase-dependent pathway role.

Microvesicles (MVs, 100-1000 nm diameter) are released into the extracellular environment by mammalian cells. MVs interact with near or remote cells through different mechanisms; in particular, MVs from human keratinocytes accelerate wound healing. Photobiomodulation by laser improves wound healing, but no information is available about its effects on MV release from human keratinocyte. Human-immortalized keratinocytes (human adult low-calcium high-temperature, HaCaT) were starved for 24 h and then irradiated using a 980-nm energy density of 0, 16.2, 32.5, and 48.7 J/cm2. After 24 h, MVs released in the conditioned medium were isolated, stained, and quantified using flow cytometry. MVs were distinguished from exosomes on the basis of their volume (forward scatter signals). In some experiments, phosphatidylinositol 3-kinase (PI-3K) activity, involved in MV release and stimulated by laser light, was inhibited by pre-treating cells with Wortmannin (WRT, 10 µg/mL). MVs were observed in HaCaT-conditioned medium both in basal- and laser-stimulated conditions. Photobiomodulation therapy, also known as PBMT, was able to increase MV release from human keratinocytes reaching a maximum effect at 32.5 J/cm2 with a stimulation of (148.6 ±15.1)% of basal (p<0.001). PI-3K activity inhibition strongly reduced both basal- and laser-induced MV release; but PBMT by laser still increased MV release, compared to basal values in the presence of WRT. In vitro near infrared photobiomodulation increased the releasing of MVs from human keratinocytes, while Wortmannin, a PI-3K inhibitor, negatively affects both basal- and laser-induced releasing. Laser-induced MV release could be a new effect of biostimulation on the wound healing process.

Correction to: Near infrared laser irradiation induces NETosis via oxidative stress and autophagy.

The published online version contains mistake on the author names. The first names and family names were interchanged. Corrected names are shown in the author group section above.

Photobiomodulation induces in vitro re-epithelialization via nitric oxide production.

Photobiomodulation is a widely used tool in regenerative medicine thanks to its ability to modulate a plethora of physiological responses. Wound re-epithelialization is strictly regulated by locally produced chemical mediators, such as nitric oxide (NO), a highly reactive free radical generated by the nitric oxide synthase (NOS) enzymatic family. In this study, it has been hypothesized that a 980-nm low-level laser stimulation could increase NO production in human keratinocytes and that such event might be directly related to the re-epithelialization process. Human keratinocytes were irradiated with increasing energy outputs (10-75 J) in the absence or presence of L-NAME, a NOS inhibitor. Laser stimulation induced an increase in NO production, resulting in an energy-dependent increase in both keratinocytes proliferation and re-epithelialization ability. The direct link between increased NO production and the observed physiological responses was confirmed by their inhibition in L-NAME pre-treated samples. Since NO production increase is a quick event, it is conceivable that it is due to an increase in existing NOS activity rather than to a de novo protein synthesis. For this reason, it could be hypothesized that photobiomodulation-derived NO positive effects on keratinocytes behavior might rely on a near infrared mediated increase in NOS conformational stability and cofactors as well as substrate binding ability, finally resulting in an increased enzymatic activity.

Near infrared laser irradiation induces NETosis via oxidative stress and autophagy.

NETosis is a novel immune defense strategy in which neutrophil activation results in the formation of extracellular DNA/protein network which is able to kill microbial populations. NETosis can be induced in vitro by lipopolysaccharide (LPS) or phorbol myristate acetate (PMA). Due to the importance of NETosis in different physiological and pathological processes, photobiostimulation effect on this neutrophil activation mechanism has been investigated. Human granulocytes, isolated from venous blood of healthy donors, were stimulated with a diode laser emitting at 980 nm with an energy intensity ranging from 0 to 75 joules. After 3 h of laser stimulation, granulocytes were fixed and colored with crystal violet in order to assess the NETosis morphology while extracellular DNA produced has been quantified using Sytox Green fluorescent dye. To evaluate ROS production and autophagy role in photobiostimulation-induced NETosis, granulocytes were pre-treated with ROS scavengers (vitamin C, sodium pyruvate, L-NAME, sodium azide), and an autophagy inhibitor (wortmannin). Laser stimulation induced an energy-dependent neutrophil extracellular trap (NET) production in human granulocytes starting from 50-J laser intensity. ROS scavengers and the autophagy inhibitor were able to abrogate both morphological features of NETosis and extracellular DNA production without modifying the basal level of NETosis. Photobiostimulation induced an increase in NET production due to an increase in ROS levels and autophagy activation.

Combining Intraoral Scans, Cone Beam Computed Tomography and Face Scans: The Virtual Patient.

PURPOSE: The aim of this literature review was to provide an update on the current scientific knowledge in the field of 3D virtual patient science and to identify a possible easy, smart, and affordable method to combine different file formats obtained from different digital devices. METHODS: Electronic searches of the Medline database was performed, up to May 2017, for articles dealing with the construction of a 3D virtual patient; the matching of data acquired with different digital devices (cone beam computed tomography, CBCT; face scanner, FS; intraoral scanner, IOS; and desktop scanner, DS) was considered. The inclusion of studies was based on the superimposition of at least 2 different digital sources. RESULTS: Twenty-five studies were selected for subsequent examination. Only 3 studies analyzed the feasibility of superimposition of 3 different types of 3D data (CBCT + FS + IOS/DS). The most frequently used matching procedure was between CBCT and FS and CBCT and IOS/DS. CONCLUSION: The procedure of superimposition of data from CBCT, IOS, and FS is currently feasible and it is now possible to create a 3D "virtual patient" to better diagnose, plan the treatment, and communicate with patients.

Prosthetic Complications Affecting Single-Tooth Morse-Taper Connection Implants.

PURPOSE: To evaluate the long-term cumulative implant survival rate (CISR%) and cumulative implant-crown success rate (CICSR%) of single-tooth Morse-taper connection implants, with particular attention to documenting the incidence of prosthetic complications. METHODS: The customized records of all patients who had been treated with single-tooth Morse-taper connection implants in 2 dental centers during the period between January 2002 and December 2012 were revisited. These records included patient-related (gender, age at surgery, smoking, bruxism), implant-related (date of insertion, site/location, and length/diameter of the implant, previous/concomitant bone regeneration), and restoration-related (date of delivery of the provisional and final crown) information. In addition, these records contained information about any implant failure and biologic and/or prosthetic complication that occurred during the follow-up period as well as the radiographic documentation. The follow-up period comprised between 5 and 15 years. The main outcomes were CISR% and CICSR%, with the latter being defined as the condition in which no complication had affected the surviving implant-supported crown during the entire follow-up. Life-table analysis was used for the analysis of CISR% and CICSR%. Peri-implant marginal bone resorption (PIMBR) at 5, 10, and 15 years was a secondary outcome of this study. RESULTS: In total, 578 patients who had received 612 implants were included in this study. The overall CISR% at 15 years was 94.8% (94.2% maxilla, 95.3% mandible). Among the surviving crowns, the overall CICSR% at 15 years was 94.5% (93.1% and 94.9% for anterior and posterior crowns, respectively), and the incidence of prosthetic complications was low (1.5%). The PIMBL amounted to 0.38 ±â€Š0.29 mm, 0.49 ±â€Š0.35 mm, and 0.94 ±â€Š0.58 mm at the 5-, 10-, and 15-year follow-ups, respectively. CONCLUSION: Morse-taper connection implants represent a reliable treatment procedure for the restoration of single-tooth gaps in the long term, with high CISR% (94.8%) at 15 years, a very low incidence of complications, and a high CICSR% (94.5%).

Assessment of Atlanto-Axial and Mandibular Rotation by Cone Beam Computed Tomography.

The cranial portion of the vertebral segment together with the atlanto-occipital joint represents a very complex area. Since this system could be influenced by different atlas and mandibular position, the aim of this work was to assess atlanto-axial and mandibular rotation. Scanora 3-dimensional cone bean computed tomography images from 205 patients without signs or symptoms of temporomandibular disorder were evaluated. Using a digitalized images analyzer, the axial rotations of atlas and mandible rotation were calculated, measuring the angle with respect to the frontal plane. The same direction for the axial rotation of the mandible and for the atlanto-axial rotation (consistent group) was observed in 80.98% of the patients; opposite directions (inconsistent group) were observed in 19.02%. Among the consistent group, the left rotation was observed in 71.08% of the patients and the right rotation in 28.92%. Absolute values showed a more marked rotation for atlas than mandible and higher values for the left rotation were reported for both.Taking together these data represents important starting points for the knowledge of atlas and mandible relationship and its functional and clinical implication.

Erbium Yttrium-Aluminum-Garnet Laser Versus Traditional Bur in the Extraction of Impacted Mandibular Third Molars: Analysis of Intra- and Postoperative Differences.

INTRODUCTION: Different osteotomy techniques have been proposed in order to improve postoperative course of impacted third molar extraction. The aim is to evaluate the possible advantages achieved with erbium yttrium-aluminum-garnet (Er:YAG) laser osteotomy compared with traditional burs. MATERIALS AND METHODS: Seventy-six extractions were randomly classified into 2 groups according to osteotomy instrument: group 1 (G1)-Er:YAG laser: 35 patients; group 2 (G2)-traditional bur: 41 patients. Intraoperative parameters: total time, stitches number, and patient compliance. Postoperative: pain, health-related quality of life (HR-QoL), need for analgesics, edema, trismus, intra- and extraoral hematoma, and postoperative complications. RESULTS: Mean time for G1 resulted 1069.4 seconds; for G2 1913.5 seconds (P < 0.0001). Mean number of stitches (P = 0.773) and patient compliance (P = 0.063) were not statistically different. Regarding pain, mean visual analog scale (VAS), and numeric rating scale (NRS) scores were lower in G1 than in G2. Statistically significant differences were highlighted at days 0, 1, and 3 with VAS scale and at days 0, 1, 3, and 7 with NRS scale. The HR-QoL scores resulted lower in G1 than in G2 (P < 0.0001). Mean facial swelling and trismus resulted statistically lower in G1 than in G2 at day 2 (P < 0.0001). Trismus resulted statistically lower in G1 than in G2 at days 2 (P < 0.0001) and 7 (P = 0.004). Two patients (5.71%) of subcutaneous emphysema was recorded in G1 and 2 patients (4.88%) of lip paresthesia in G2. CONCLUSION: Data confirm that the use of Er:YAG laser for osteotomy may achieve several advantages both technical and biological.

Diode Laser Clinical Efficacy and Mini-Invasivity in Surgical Exposure of Impacted Teeth.

The gold standard to arrange impacted teeth in the dental arch is represented by a surgical approach followed by orthodontic traction force application. In the literature, many surgical approaches are proposed to reach such a scope. The aim of the present study is to demonstrate how laser technique could positively assist surgical approaches.Study population was composed by 16 patients undergoing orthodontic treatment of 20 impacted teeth. In 10 patients (population A) surgical exposure of the impacted teeth was performed using a 980 nm diode laser, while in the other 10 patients (population B), surgical incision was performed using a traditional lancet.Only 3 patients of the population A needed local anesthesia for surgical procedure while the remaining 7 patients reported only faint pain during surgery. Two patients referred postsurgical pain (numerical rating scale average value = 2) and needed to take analgesics. None of the patients showed other postsurgical side effects (bleeding, edema).All population B patients needed infiltrative anesthesia and referred postsurgical pain (numerical rating scale average value >4) treated with analgesics. Moreover, in such population, 4 patients referred lips edema while 4 showed bleeding and 6 needed surgical sutures of soft tissues.The lack of side effects of laser surgical approach to expose impacted teeth must persuade dental practitioners to choose such a clinical approach to closed surgical approach every time it is possible.

Laser-induced osteoblast proliferation is mediated by ROS production.

Low-level laser therapy (LLLT) is widely used in regenerative medicine and in dental therapy by virtue of its beneficial effects in a plethora of pathological conditions. In this study, the effect of a 980 nm diode laser on pre-osteoblasts proliferation has been evaluated, along with reactive oxygen species (ROS) production. We hypothesized that ROS were a key factor in LLLT-induced pre-osteoblasts proliferation, as it is known that ROS can induce the activation of many biological pathways, leading to cell proliferation, differentiation or apoptosis. Murine pre-osteoblasts MC3T3 cells were irradiated with different energy outputs (1-50 J) in the absence or presence of the antioxidant N-Acetyl-L-cysteine (NAC). Laser treatment, in the absence of NAC, was able to induce a fluence-dependent statistically significant increase in ROS generation, while the presence of NAC strongly inhibited it. Cell proliferation, measured after laser stimulation, was significantly increased both at low and higher energy, with a peak at 10 J in the absence of the antioxidant. On the contrary, in the presence of NAC, laser irradiation was not able to induce any cell proliferation, suggesting a crucial role of ROS in this laser-induced cell effect. These results suggest that LLLT may be a useful tool for bone regeneration therapy and an effective range of fluences to be used is indicated.

Effect of zirconium nitride physical vapor deposition coating on preosteoblast cell adhesion and proliferation onto titanium screws.

STATEMENT OF PROBLEM: Titanium has long been used to produce dental implants. Problems related to its manufacturing, casting, welding, and ceramic application for dental prostheses still limit its use, which highlights the need for technologic improvements. The aim of this in vitro study was to evaluate the biologic performance of titanium dental implants coated with zirconium nitride in a murine preosteoblast cellular model. PURPOSE: The purpose of this study was to evaluate the chemical and morphologic characteristics of titanium implants coated with zirconium nitride by means of physical vapor deposition. MATERIAL AND METHODS: Chemical and morphologic characterizations were performed by scanning electron microscopy and energy dispersive x-ray spectroscopy, and the bioactivity of the implants was evaluated by cell-counting experiments. RESULTS: Scanning electron microscopy and energy dispersive x-ray spectroscopy analysis found that physical vapor deposition was effective in covering titanium surfaces with zirconium nitride. Murine MC-3T3 preosteoblasts were seeded onto titanium-coated and zirconium nitride-coated screws to evaluate their adhesion and proliferation. These experiments found a significantly higher number of cells adhering and spreading onto zirconium nitride-coated surfaces (P<.05) after 24 hours; after 7 days, both titanium and zirconium nitride surfaces were completely covered with MC-3T3 cells. CONCLUSIONS: Analysis of these data indicates that the proposed zirconium nitride coating of titanium implants could make the surface of the titanium more bioactive than uncoated titanium surfaces.

Role of vitamin D for orthodontic tooth movement, external apical root resorption, and bone biomarker expression and remodeling: A systematic review.

Objective: : This systematic review aimed to evaluate the correlation between vitamin D levels and the rate of tooth movement, external apical root resorption, bone biomarker expression, and bone remodeling. Methods: : Three databases (PubMed, Scopus, and Web of Science) were systematically searched from inception until 14th March 2023 to identify studies investigating the correlation between orthodontic tooth movement and vitamin D in animals and humans. The quality assessment was made in accordance with the Joanna Briggs Institute Critical Appraisal Checklist. Results: : Overall, 519 records were identified, and 19 were selected for the qualitative synthesis. Eleven studies investigated the effect of local administration (injections in the periodontal ligament, to the gingiva distal to the teeth, or submucosae palatal area) and systemic administration (oral supplementation) of vitamin D on tooth movement, external apical root movement, pro-inflammatory cytokines, and bone remodeling factors. The remaining eight studies investigated the correlation between serum vitamin D levels and salivary vitamin D levels on bone turnover markers and tooth movement. Conclusions: : The findings of this systematic review support that vitamin D3 local injections might increase the rate of tooth movement via the receptor activator of the nuclear factor-kB/osteoprotegerin axis. However, the non-uniform study designs and the different protocols and outcome methods make it challenging to draw reliable conclusions.

Polydopamine Blending Increases Human Cell Proliferation in Gelatin-Xanthan Gum 3D-Printed Hydrogel.

BACKGROUND: Gelatin-xanthan gum (Gel-Xnt) hydrogel has been previously modified to improve its printability; now, to increase its ability for use as cell-laden 3D scaffolds (bioink), polydopamine (PDA), a biocompatible, antibacterial, adhesive, and antioxidant mussel-inspired biopolymer, has been added (1-3% v/v) to hydrogel. METHODS: Control (CT) and PDA-blended hydrogels were used to print 1 cm2 grids. The hydrogels' printability, moisture, swelling, hydrolysis, and porosity were tested after glutaraldehyde (GTA) crosslinking, while biocompatibility was tested using primary human-derived skin fibroblasts and spontaneously immortalized human keratinocytes (HaCaT). Keratinocyte or fibroblast suspension (100 µL, 2.5 × 105 cells) was combined with an uncrosslinked CT and PDA blended hydrogel to fabricate cylinders (0.5 cm high, 1 cm wide). These cylinders were then cross-linked and incubated for 1, 3, 7, 14, and 21 days. The presence of cells within various hydrogels was assessed using optical microscopy. RESULTS AND DISCUSSION: PDA blending did not modify the hydrogel printability or physiochemical characteristics, suggesting that PDA did not interfere with GTA crosslinking. On the other hand, PDA presence strongly accelerated and increased both fibroblast and keratinocyte growth inside. This effect seemed to be linked to the adhesive abilities of PDA, which improve cell adhesion and, in turn, proliferation. CONCLUSIONS: The simple PDA blending method described could help in obtaining a new bioink for the development of innovative 3D-printed wound dressings.

Effect of air polishing with glycine powder on titanium abutment surfaces.

OBJECTIVE: The aim of the present study was to evaluate morphological changes induced by glycine powder air polishing on titanium surfaces and its effect on bacteria recolonization in comparison with sodium bicarbonate powder. MATERIALS AND METHODS: 5 mm wide and 1 mm thick titanium grade II disks were divided into three groups of treatments: (i) no treatment; (ii) air polishing with glycine powder; (iii) air polishing with sodium bicarbonate powder. Specimens were characterized by laser profilometry, scanning electron microscopy (SEM) and then installed onto removable appliances worn for 24 h by healthy volunteers. Surface contamination was evaluated using SEM and counting the number of colony forming units (CFU). RESULTS: SEM observation revealed an increased roughness with the formation of craters on samples treated with sodium bicarbonate powder, while not in glycine ones. Statistical analysis failed to show significant differences of both Ra and Rmax parameters in treated groups. SEM observation of specimens surfaces, after 24 h of permanence in the oral cavity, showed a higher contamination of the disks treated with sodium bicarbonate compared with those not treated (P < 0.05). Conversely, the group treated with glycine showed the lower contamination if compared with bicarbonate-treated group (P < 0.05). CONCLUSIONS: Air polishing with glycine powder may be considered as a better method to remove plaque from dental implant because glycine is less aggressive than sodium bicarbonate powder. Moreover, the use of glycine powder seems to have an active role on the inhibition of bacterial recolonization of implants in a short test period (24 h). Further studies are needed to demonstrate the bacteriostatic properties of glycine, envisaged on the basis of reduced contamination of the disks polished with glycine compared with those not treated.

Low zoledronate concentrations stimulate human keratinocyte proliferation.

AIM: To evaluate, in an in vitro wound healing model, the effect of zoledronate on keratinocyte cellular behavior. MATERIALS AND METHODS: Human spontaneously immortalized keratinocytes (HaCaT) were treated with low zoledronate concentrations (10 nmol/l to 10 µmol/l) and its effect on cell proliferation was evaluated by means of a fluorescent assay (Tox-8), along with the analysis of cytokeratin 5 and filaggrin gene expression. Moreover, zoledronate effects on cell migration were evaluated by in vitro wound healing, and matrix metalloproteinase (MMP) activity was investigated by gelatin zymography. RESULTS: At the tested concentrations, zoledronate stimulated keratinocyte proliferation, upregulating cytokeratin 5 while downregulating filaggrin expression and wound healing ability, without any significant effect on MMP-9 activity. The lack of zoledronate effects on MMP-9 activity indicates that, in our experimental model, wound closure is mainly due to an increase in cell proliferation rather than an increase in cell migration. Moreover, the observed increase in cell proliferation could be ascribed to a zoledronate-mediated reduction of farnesyl pyrophosphate endogenous levels. CONCLUSIONS: These results could foster new clinical applications for this 'old' drug in the field of epithelial regeneration.