Glycine Powder Research Articles

To evaluate and compare the efficacy of glycine and chitosan powder to regain the osseo‐conductivity of contaminated titanium surfaces: an in‐vitro study

To evaluate and compare the efficacy of glycine and chitosan powder to regain the osseo‐conductivity of contaminated titanium surfaces: an in‐vitro study

Comparison of different standardised bond strength tests and the influence of glycine powder treatment in composite resin repairs

Aim: The repair of restorations is an eligible method to extend the survival rates of intraoral restorations. There is a consensus that the old surface has to be removed before repair by the use of a sandblaster or rotating instruments. This study aimed to investigate whether a glycine powder can be used successfully in composite repair by measurement of shear and tensile bond strength according to dental standards.
 Methodology: The influence of mechanical preparation by no powder, 25 µm glycine powder or 50 µm aluminium-oxide powder and chemical conditioning by the use of bonding, phosphoric acid and bonding or bonding, phosphoric acid and a silane on the repair bond strength of an artificially aged nano-hybrid composite was tested according to the guidelines of DIN 13990 (2017), ISO 29022 (2013) and ISO/TS 11405 (2015). The fracture modes were evaluated by adhesive, cohesive or mixed failures.
 Results: There was no significant difference in the performance of the different mechanical and chemical treatments. The shear bond test according to DIN 13990 (2017) produces higher repair bond strengths (26.0±8.9 MPa) than the test described in ISO 29022 (17.9±6.3 MPa). The tensile bond strength according to ISO/TS 11405 (6.9±1.8 MPa) was the lowest. Most adhesive failures occurred with the shear test according to ISO 29022 (41%), followed by DIN 13990 (18%) and the tensile test (4%).
 Conclusion: For evaluating the bond strength of composites the test described in ISO 29022 is recommended, because it produces the highest percentage of adhesive failures. Nano-hybrid-composites are robust to different repair protocols.
 
 How to cite this article:
 Herrmann GP, Reimann S, Daratsianos N, Weber A, Keilig L, Nadal J, Bourauel C. Comparison of different standardized bond strength tests and the influence of glycine powder treatment in composite resin repairs. Int Dent Res 2020;10(1):36-43. https://doi.org/10.5577/intdentres.2020.vol10.no2.2 
 
 Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.

Comparison between four different implant surface debridement methods: an in-vitro experimental study.

Peri-implantitis treatment is a very challenging topic to discuss. What is certain is that preventive/supportive therapy plays a key-role in peri-implant tissues' health maintenance and non-surgical implant surface mechanical debridement remains one of the solid pillars in the therapeutic pathway. In this perspective, many surface decontaminating methods have been proposed and tested to remove hard and soft bacterial deposits. The aim of this study was to compare four different commonly used non-surgical implant debridement methods in terms of cleaning potential in vitro, using a peri-implant pocket-simulating model. Sixty-four dental implants were ink-stained and placed into a simulated peri-implant pocket. Samples were then divided into four groups and treated with different debridement methods: stainless-steel ultrasonic tip (PS), peek-coated ultrasonic tip (PI), sub-gingival air-polishing with erythritol powder (EHX) and sub-gingival air-polishing with glycine powder (GLY). For each treatment group, half of the samples were treated for 5 seconds and the other half for 45 seconds. High-resolution images were taken using a digital microscope and later analyzed with a light processing software for measuring the cleaned area percentage (ink-free). Two different images were captured for every sample: a first image with the implant positioned perpendicular to the microscope lenses (90°) and a second one with the implant placed with a 45° vertical angulation, with the smooth neck towards the ground. Percentage of removed ink was statistically modelled using a generalized linear mixed model with the implant as a random (clustering) factor. A paired comparison between all treatments in terms of debridement potential (cleaned area percentage) was performed. In 5s and with 90° sample angulation EHX/PS comparison showed an odds ratio of 2.75 (P<0.001), PI/EHX an OR of 0.20 (P<0.001), GLY/PS an OR of 2.90 (P<0.001), PI/GLY an OR of 0.19 (P<0.001) and PI/PS an OR of 0.56 (P=0.105). With the same sample angulation and 45s treatment time, the OR was 6.97 (P<0.001) for EHX/PS comparison, 0.14 (P<0.001) for PI/EHX comparison, 4.99 (P<0.001) for GLY/PS, 0.19 (P<0.001) for PI/GLY and 0.95 for PI/PS (P =0.989). With 5s of treatment time and 45° sample angulation, EHX/PS comparison shows a 3.19 odds ratio (P<0.001), PI/EHX a 0.14 odds ratio (P<0.001), GLY/PS a 3.06 odds ratio (P<0.001), PI/GLY a 0.15 odds ratio (P<0.001) and PI/PS a 0.46 odds ratio (P=0.017). With the same sample angulation but 45s treatment time, EHX/PS comparison produced an odds ratio of 4.90 (P<0.001), PI/EHX an OR of 0.20 (P<0.001), GLY/PS an OR of 8.74 (P<0.001), PI/GLY an OR of 0.11 (P<0.001) and PI/PS an OR 0.96 of (P =0.996). Among the four treatments considered, air-polishing therapy represents the best one in terms of ink removal from the implant surface. Furthermore, increasing the treatment time to 45 seconds, air-polishing resulted considerably more efficient.

Short-term comparison of two non-surgical treatment modalities of peri-implantitis: Clinical and microbiological outcomes in a two-factorial randomized controlled trial.

To compare the efficacy of two different therapies (amino acid glycine abrasive powder and a desiccant material) and their combination in the non-surgical treatment of peri-implantitis. This was an examiner-blind randomized clinical trial, with 2-factorial design with a follow-up of 6months. The combination of the two factors resulted in four interventions: (a) non-surgical debridement alone (C); (b) non-surgical debridement and a desiccant material (H); (c) non-surgical debridement and glycine powder (G); and (d) non-surgical debridement, desiccant material and glycine powder (HG). Sixty-four patients with peri-implantitis were randomized, 16 for each intervention. After six months, two implants failed in the G intervention. Mean pocket depth reduction was higher in patients treated with the desiccant material (estimated difference: 0.5mm; 95% CI from 0.1 to 0.9mm, p=.0229) while there was no difference in the patients treated with glycine powder (estimated difference: 0.1mm; 95% CI from -0.3 to 0.5mm, p=.7333). VAS for pain during intervention and VAS for pain after one week were higher for patients treated with glycine powder (p=.0056 and p=.0339, respectively). The success criteria and other variables did not reveal differences between interventions. In this 6-month follow-up study, pocket reduction was more pronounced in patients using the desiccant material. Pain was higher in patients using glycine. All the interventions resulted in low success rate.

Detoxified dental healing abutments trigger an inflammatory response in-vitro

Abstract Healing abutment (HA) is a titanium screw used in implant dentistry to replace missing teeth. Although designed for single procedure, HA are frequently reused. Pathogen Associated Molecular Patterns (PAMPs), present on HA can elicit immune responses in vivo and may lead to implant failure. The aim of this study is to test four commonly employed protocols for HA detoxification. Forty HA collected from subjects with prior implant placement were randomly distributed and detoxified using four protocols (A–D, N=10/group). Group A: Autoclave sterilized, Group B: Ultrasonic bath + autoclave, Group C: Debrided by prophy jet and glycine powder + autoclave, Group D: Debrided using a non-scratch scrub sponge + autoclave, Control: Unused. Residual protein quantification (N=3/group) and macroscopic debris evaluation (N=2/group) was assessed by Protein BCA Assay Kit and Phloxine B staining, respectively. Human primary monocyte-derived macrophages (Mϕ) were challenged with HA (N=5/group) and supernatants were collected at 4, 24, 48 and 120 h to analyze ten cytokines by multiplex bead assay. Control group did not show any detectable protein, debris or cytokine production. Among the treatments, protocol C and D were highly effective in decontamination as observed by reduced protein and debris quantification. Protocol C showed reduced cytokine (TNF-α, IL-8, IL-6, IL-10 and CXCL-10) secretion both at early and late time points compared to other decontamination protocols (A, B or D). The most effective detoxification method for HA is Protocol C. Compared to unused HA, none of the protocols completely decontaminated HA. Potent immunogenicity of decontaminated HA suggests that the practice to reuse HA should be reconsidered.

The Prevention of Implant Surface Alterations in the Treatment of Peri-Implantitis: Comparison of Three Different Mechanical and Physical Treatments.

The surgical treatment of peri-implantitis is currently based on the removal of biofilms from the implant surface by primary means of mechanical and physical treatments. However, such approaches often determine some alterations of the implant surface with detrimental effects on re-osseointegration. This study aims to evaluate the effects of four different mechanical and physical treatments on titanium samples with moderately rough surface. Air powder abrasion (AP) with glycine powder, a titanium brush (TB) and a diode laser at 3 W (L3) and 4 W (L4) were tested. Surface morphology, roughness and chemical composition were then assessed by scanning electron microscope (SEM), white light interferometer and X-ray photoelectron spectroscopy (XPS), respectively. The microscopic analysis revealed significant alterations in surface morphology on TB samples, while AP and L3 had only a minor or null impact. L4 samples revealed signs of overheating due to the excessive power. Nevertheless, the overall roughness of the samples was not significantly altered in terms of roughness parameters. Similarly, surface chemical composition was not significantly affected by the treatments. Among the treatments tested in this study, air powder abrasion with glycine powder and 3 W diode laser had the lowest impact on surface physicochemical properties.

A subgingivális air-abrazív terápia hozzáadott hatása a krónikus parodontitis nem-sebészi kezelésében

A parodontitis kezelésében a mai napig elengedhetetlen a subgingivális debrimentálás, amelynek hatékonyságát többféle kiegészítő terápiával próbálják fokozni, így az általunk jelen klinikai kísérletben használt subgingivális air-abrazív készülék alkalmazásával is.A kutatás első fázisában 8 páciens klinikai paramétereinek változását tudtuk értékelni „split-mouth” vizsgálatunkban, a tesztoldalon a hagyományos eszközökkel végzett subgingivális debrimentálást subgingivális air-abrazív kezeléssel egészítettük ki glycin por felhasználásával.Egy hónappal a beavatkozás után statisztikailag értékelhető különbséget nem találtunk a teszt- és a kontrolloldal között, a klinikai paraméterek mindkét oldalon szignifikáns javulást mutattak. A további szignifikáns javulás a tesztoldalon volt észlelhető a terápiát követő 3 hónap után elvégzett mérések szerint, és különösen a nehezen hozzáférhető helyeken (mély tasak, többgyökerű fogak) volt kedvezőbb az air-abrazív módszer kiegészítő hatása.Jelen, kis mintán végzett vizsgálatunkból azt a megállapítást tehetjük, hogy az air-abrazív módszer kiegészítő hatása a subgingivális debrimentálás hosszabb távú sikeréhez és a nehezebben hozzáférhető területek eredményesebb kezeléséhez vezethet.

The choice of auxiliary substances to obtain sublingual glycin tablets with thiotriazoline with direct compaction method Reporting 1. Study of the influence of excipients on the bulk density, the bulk density after shrinkage, the fluidity and the angle o

Today in Ukraine, stroke remains the second and most common cause of premature mortality and disability. More than 111.000 new cases of stroke occur every year in Ukraine. This is a very topical medical and social problem worldwide. Today, a promising area of primary neuroprotection in cerebral ischemia is to correct the imbalance of excitatory and inhibitory neurotransmitter systems through the activation of natural inhibitory processes. Our attention was drawn to the natural inhibitory neurotransmitter glycine and its role in the mechanisms of acute cerebral ischemia. There is evidence of the ability of the thiotriazoline antioxidant to potentiate the therapeutic effect of neurometabolic cerebroprotectors. Based on this, we have created a new combination drug based on glycine with thiotriazoline. For the new combination drug, a rational dosage form of the tablet was selected. The purpose of this work is to select excipients for producing glycine tablets with thiotriazoline by direct compression, to study their effect on bulk density, bulk density after shrinkage, fluidity, and angle of natural inclination. Materials and methods. The studies were used: glycine (manufacturer: China); Thiotriazoline (manufacturer: State Enterprise Chemical Reagents Plant of the Institute of monocrystals of the NAS of Ukraine), certified excipients based on microcrystalline cellulose, granulated sugars, granulated inorganic salts, lubricating as well as domestic. At first, morphometric studies of glycine powders, thiotriazoline, and mixtures of glycine with thiotriazoline were conducted. In the course of the work, four groups of excipients, factors, and their levels were studied. To study the four qualitative factors, we used the Greek-Latin square 4 × 4. The bulk density, the bulk density after shrinkage, the fluidity, and the angle of the natural slope of the glycine powder masses with thiotriazoline were studied. Results . According to the results of the experimental studies, the variance analysis of the experimental data was carried out and conclusions were drawn about the influence of the studied factors on the quality parameters of the glycine powder masses with thiotriazoline Conclusions. In the course of the researches, the influence of four groups of excipients on the bulk density, the bulk density after shrinkage, the fluidity, the angle of the natural slope of the glycine powder masses with thiotriazoline were studied. According to the results of the analysis of variance, optimum auxiliaries were selected which provide quality according to the studied parameters.

Ignition characteristics of amino acid powders

Herein, the ignition characteristics, including the minimum ignition energy (MIE) and minimum explosible concentration (MEC), of amino acid powders (L-leucine, L-valine, L-threonine, L-alanine, and L-serine) were experimentally investigated. The MIE and MEC values of branched-chain amino acid (BCAA) powders were much lower than those of the other powders such as L-threonine, L-alanine, L-serine and glycine powders. In particular, the MEC values for the BCAAs were constant, notwithstanding increasing particle size. The plateau range of BCAA particle size was wider than that of the other carbonaceous particles tested. Pyrolysis of the powders and the resultant pyrolyzates were investigated by thermogravimetry (TG) and the pyrolysis-gas chromatography-mass spectrometry (PyGCMS). A number of flammable materials were formed from the BCAAs, compared with the other amino acids tested. In addition, the propagating flame structure was discussed and different flame structures for the BCAAs were observed depending on the particle size distribution. The flame front for relatively small particle sizes was continuously smooth, whereas that for relatively large particle sizes was discrete. These results indicated that the BCAAs are sensitive to ignition and exhibit a high risk of dust explosion during the manufacturing process.

Combining various non‐surgical techniques for treating peri‐implantitis – A randomized clinical trial

Background Non-surgical treatment of peri-implantitis is targeted at mechanical and or chemical disinfection of the implant and its suprastructures, to allow inflamed peri-implant tissues to heal. Many different surgical and non-surgical techniques for the treatment of peri-implantitis have been investigated, with varying results. However, a combination of various non-surgical techniques in a single treatment session in a full-mouth disinfection protocol has not been investigated yet. Aim/Hypothesis To determine if a combination of various non-surgical techniques in a single treatment session, comprised of using hand curettes and carbon-tipped ultrasonic, air abrasion, and Er-YAG-laser therapy in a full-mouth disinfection protocol, leads to short-term resolution of peri-implantitis. Material and Methods 27 patients with one or more dental implants with clinical and radiographic signs of peri-implantitis were divided ad random into two groups. The test group (11 patients, 31 implants) received debridement of the affected implants, using hand curettes, carbon-tipped ultrasonics, air-abrasion with glycine powder and Er-YAG-laser irradiation. Additionally, full-mouth disinfection was performed on all teeth with pockets > 4 millimeters. The control group (16 patients, 30 implants) received debridement of the implants only by hand curettes. This group did not undergo a full-mouth disinfection. For both groups, all treatments were performed in a single session. Bleeding on probing (BoP) scores, peri-implant probing depths (PPD), clinical attachment levels (CAL), interproximal bone levels (BL) and full-mouth plaque scores (FMPS) were recorded at intake and at 3 and 6 months after treatment. Results The test group showed statistically significantly more reduction in bleeding on probing scores at the 3 and 6 months of follow-up despite of an increase of scores in the test group in between 3 and 6 months after treatment. Both groups showed a statistically significant decrease in PPD after 3 months (P = 0.009 and P = 0.0008 for the control and test groups respectively). The difference in decrease between both groups was statistically significant in favor of the test group (P = 0.0001). At 6 months an increase in PPD was observed for both groups. The difference at 6 months was no longer statistically significant. Changes in bone level from intake to 3 months and 6 months after treatment were not statistically significant. Neither were differences in bone level changes in between both groups. Conclusion and Clinical Implications A more thorough debridement protocol can result in greater resolution of inflammation in the peri-implant tissues and the effects can be sustained up to 6 months after treatment. Clinically this implicates that a more comprehensive mechanical and or chemical disinfection protocol is beneficial for the treatment of implants affected by peri-Implantitis.

Biofilm as a risk factor in implant treatment.

This article summarizes the microbiological findings at dental implants, drawing distinctions between the peri-implant microbiome and the periodontal microbiome, and summarizes what is known regarding biofilm as a risk factor for specific stages of implant treatment. Targeted microbial analysis is reviewed as well as the latest results from open-ended sequencing of the peri-implant flora. At this time there remains a lack of consensus for a specific microbial profile that is associated with peri-implantitis, suggesting that there may be other factors which influence the microbiome such as titanium surface dissolution. Therapeutic interventions to address the biofilm are presented at the preoperative, perioperative, and postoperative stages. Evidence supports that perioperative chlorhexidine reduces biofilm-related implant complications and failure. Regular maintenance for dental implants is also shown to reduce peri-implant mucositis and implant failure. Maintenance procedures should aim to disrupt the biofilm without damaging the titanium dioxide surface layer in an effort to prevent further oxidation. Evidence supports the use of glycine powder air polishing as a valuable adjunct to conventional therapies for use at implant maintenance visits. For the treatment of peri-implantitis, nonsurgical therapy has not been shown to be effective, and while surgical intervention is not always predictable, it has been shown to be superior to nonsurgical treatment for decontamination of the implant surface that is not covered by bone.

Surface changes and bacterial adhesion on implant abutment materials after various clinical cleaning procedures.

Supportive treatments are essential to long-term dental implant success; however, professional cleaning procedures may alter the surfaces of implant abutments and lead to adverse biological responses. This study aimed to evaluate four clinically used cleaning procedures by examining surface changes and subsequent bacterial adhesion on abutment materials. Discs of titanium and zirconia were polished and divided into five groups: titanium curette treatment, carbon fiber reinforced plastic curette treatment, ultrasonic scaling with carbon fiber tip treatment, air polishing with glycine powder, and control group without any treatment. After instrumentation, the arithmetical mean roughness (Ra), hydrophilicity, and surface free energy were recorded. The bacterial adhesion was evaluated after 1 h of Streptococcus mitis incubation by optical microscope and quantified by turbidity test. Among the titanium samples, titanium curette treatment group showed significant surface morphology changes, increased Ra, hydrophilicity, surface free energy, and higher optical density of adhered bacteria. As for the zirconia samples, the differences in surface morphology, Ra, and bacterial adhesion between groups were nonsignificant. Comparing to titanium, zirconia was less susceptible to surface changes after tested cleaning procedures. Titanium curette should be used with care on titanium abutments.

Tissue phantom to mimic the dielectric properties of human muscle within 20 Hz and 100 kHz for biopotential sensing applications.

Tissue-mimicking materials for phantoms are fabricated for research purposes to simulate the mechanical or electrical properties of real human tissues and promote better understanding of their properties. This research investigated the dielectric properties (from 20 Hz to 100 kHz) of five promising muscle mimicking materials including matrix materials (gelatin powder and agar powder), and fillers (sodium chloride, glycine and aluminum powder) for the development of muscle phantoms. The mechanical behaviors were verified as well. This research determined the effects of electrode polarization (EP) on the dielectric properties of each material and then used a mathematical model to reduce these unwanted effects. Additionally, the results indicated the very low dielectric properties of gels-only samples. Both electrical conductivity and relative permittivity increased with increasing concentrations of fillers. Moreover, all fillers had their own capabilities to alter the levels and trends in the increments of dielectric values, which provide a wider selection to muscle-mimicking materials. Theoretically, it is feasible to achieve desired dielectric properties by mixing these fillers together with certain ratios. In this way, low-cost muscle phantoms can be produced and used as experimental subjects for biopotential sensing application.

Effect of temporary cement removal methods from human dentin on zirconia-dentin adhesion

This study evaluated the effect of temporary cement residue removal methods from human coronary dentin on the bond strength of adhesively-luted zirconia on dentin. Forty non-carious human molars were embedded in acrylic resin and the dentin surfaces were exposed. Temporary acrylic crowns were provisionally cemented with zinc oxide cement without eugenol and stored in distilled water (37 °C/15 days). After crown removal, the excess temporary cement was removed from dentin according to one of the following cleaning methods: (n = 8 per group): (a) air-water rinse (AW), (b) pumice paste (PP), (c) air-abrasion with aluminum oxide particles (Al2O3) (AA), (d) sodium bicarbonate spray (SB) or (e) glycine powder (CP). Forty zirconia cylinders were made and each cylinder was adhesively luted onto each tooth after adhesive resin (Scotch Bond Universal, 3 M ESPE-SBU) application using resin cement (RelyX Ultimate, 3 M ESPE) and photo-polymerized from each surface for 20 s. The bonded specimens were stored in distilled water (37 °C) for 90 days. The bonded interface was loaded under shear (1 mm/min). Data (MPa) were analyzed using 1-way ANOVA and Tukey's test (α = 0.05). Mean bond strength was significantly affected by the cleaning method (p = 0.0289). Cleaning with AA method resulted in significantly higher bond strength than with SB (p < 0.05) but similar to CP, PP and AW (p > 0.05). All cleaning methods were effective in removing temporary resin cement from dentin surfaces. Air-abrasion with aluminum oxide particles was more effective than with sodium bicarbonate spray promoting adhesion between zirconia and dentin.

In vitro efficacy of three different implant surface decontamination methods in three different defect configurations

Evaluation of in vitro efficacy of three different implant surface decontamination methods in a peri-implant bone defect model. A total of 180 implants were stained with indelible red color and distributed to standardized peri-implant bone defect resin models with a circumferential defect angulation of 30°, 60°, or 90° (supraosseous defect). Sixty implants were assigned to each type of defect. All implants were cleaned by the same examiner. For each type of defect, 20 implants were cleaned for 2min with one of 3 devices: curette (CUR), sonicscaler (SOSC), or air abrasion with glycine powder (APA). Thereafter, photographs were taken from both sides of each implant and the cumulative uncleaned implant surface area was measured by color recognition technique. Scanning electron micrographs (SEM) were examined to assess morphologic surface damages. The cleaning efficacy as percent (%) of residual color was significantly different for each of the 3 defect angulations (p<0.001) for each treatment device: 30° CUR: 53.44% > SOSC: 19.69% > APA: 8.03%; 60° CUR: 57.13% > SOSC: 11.4% > APA: 0.13%; and 90° CUR: 48.1% > SOSC: 13.07% > APA: 0.58%. The differences between the three different cleaning modalities within each defect type were also significant (p<0.005). SEM micrographs showed no surface damages after the use of APA. Air powder abrasion is the most efficient (APA>SOSC > CUR) and less surface damaging treatment modality for each defect angulation in this in vitro model.

Minimum ignition energy and minimum explosible concentration of L-isoleucine and glycine powder

In this study, Minimum Ignition Energy (MIE) and Minimum Explosible Concentration (MEC) of L-isoleucine and glycine powder with two different particle size distributions were experimentally investigated. The experimental results showed that the values of MIE and MEC of L-isoleucine powder were lower than those of glycine powder. The pyrolysis and the combustible products of glycine and L-isoleucine powders were measured. The results showed that a number of flammable and combustible materials are formed during the pyrolysis of L-isoleucine, although few flammable compounds are generated during the pyrolysis of glycine due to polymerization. This result indicated that the L-isoleucine powder has a high risk of dust explosion as compared to the glycine powder. Consequentially, an appropriate risk assessment for the L-isoleucine powder with fine particles is necessary in the powder handle processes.

Microbiological dynamics of red complex bacteria following full-mouth air polishing in periodontally healthy subjects-a randomized clinical pilot study.

Suppression of periodontal pathogens in the oral cavity of periodontally healthy individuals may lower the risk for periodontal or periimplant diseases. Therefore, the present study aimed to analyze the effect of supragingival debridement (SD) with adjunctive full mouth glycine powder air polishing (FM-GPAP) on the prevalence of periodontal pathogens in periodontally healthy individuals. Eighty-seven systemically and periodontally healthy intraoral carriers of red complex bacteria, i.e., Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola or other periodontal pathogens including Aggregatibacter actinomycetemcomitans, Prevotella intermedia, and Eikenella corrodens were enrolled into the study and randomly assigned to receive SD with adjunctive FM-GPAP (test, n= 42) or SD alone (control, n = 45). In the first observation period, microbiological samples were obtained prior to, and 2, 5, and 9days following intervention. If one of these periodontal pathogens could still not be identified, additional microbial sampling was performed after 6 and 12weeks. The prevalence of red complex bacteria was significantly reduced in the test compared to the control group following treatment (p = 0.004) and at day 9 (p = 0.031). Intragroup comparison showed a significant (test, p < 0.001; control, p ≤ 0.01) reduction in the mean prevalence in both groups from BL through day 9 with an additional significant intergroup difference (p = 0.048) at day 9. However, the initial strong reduction returned to baseline values after 6 and 12weeks. In periodontally healthy carriers of periodontal pathogens, FM-GPAP as an adjunct to SD transiently enhances the suppression of red complex bacteria. Whether the enhanced suppression of red complex bacteria by adjunctive FM-GPAP prevents the development of periodontitis in periodontally healthy carriers requires further investigations.

Quasi-Equilibria and Polarization Transfer Between Adjacent and Remote Spins: 1H-13C CP MAS Kinetics in Glycine.

The 1H-13C CP MAS kinetic curves were measured in glycine powder sample at the MAS rates of 7, 10, and 12 kHz. Each experimental curve contained up to 1000 equidistant points over the whole contact time range of 10 μs - 10 ms. The CP kinetic data for CH2 group, i.e., for the system containing adjacent 1H-13C spin pairs with a definite dominant dipolar coupling can be described in the frame of the isotropic spin-diffusion approach. The local order parameter ⟨ S⟩ ≈ 1.0, determined as the ratio of the measured dipolar 1H-13C coupling constant and the calculated static dipolar coupling constant, is very close to the values deduced in series of other amino acids. The strong narrow peaks observed in the spin coupling spectrum at multiples of the MAS frequency can be considered as the confirmation that the periodic quasi-equilibrium state can appear also in the powder samples. The anisotropic spin-diffusion approach improved by the introducing of the thermal equilibration in the proton bath is the most proper model to describe the CP kinetics in the system containing remote spins. Very realistic values of the spin-cluster size ( N) have been obtained without any constraint on the flow of the nonlinear curve fitting. The finite values of N ≤ 4 means that CP transfer is located within one glycine molecule.

PR380: Air‐polishing with glycine and erythritol powders on periodontally compromised teeth: an in vitro study

PR380: Air‐polishing with glycine and erythritol powders on periodontally compromised teeth: an in vitro study

Subgingival glycine powder air-polishing as an additional approach to nonsurgical periodontal therapy in subjects with untreated chronic periodontitis.

Glycine powder air-polishing (GPAP) is an alternative approach to removing subgingival plaque biofilms for effective periodontal therapy. This study aimed to investigate the effect of subgingival GPAP as an additional approach to nonsurgical periodontal treatment in subjects with chronic periodontitis. Twenty-seven nonsmoking subjects were recruited. Two quadrants in each subject were randomly assigned, according to a split-mouth design, to receive scaling and root planing (SRP) and GPAP (Test group) or SRP and air flushing with water (Control group) at sites with probing depth ≥5mm. Clinical parameters, gingival crevicular fluid volumes and the concentrations of interleukin-1β and interleukin-1ra in gingival crevicular fluid were measured at baseline and 1, 3 and 6months after the treatments. At baseline, no statistically significant difference in periodontal and gingival crevicular fluid parameters was found between the Test and Control groups. Overall, the periodontal conditions of all subjects showed significant improvement after the treatments. Notably, the Test group showed greater reduction in gingival crevicular fluid volume (0.37±0.26μL) than the Control group (0.23±0.30μL) at 3months (P<.05). The gingival crevicular fluid levels of interleukin-1β and interleukin-1ra showed a significant decrease in both groups at 6months, and no significant difference was found between the groups. These preliminary results suggest that GPAP, as an additional approach to nonsurgical periodontal treatment, may be beneficial for the short-term improvement of subclinical inflammation when measured by gingival crevicular fluid volume. Further longitudinal studies with larger sample sizes are required to clarify the exact benefits of GPAP treatment for controlling inflammation and maintaining long-term periodontal health.