INNOVATION IN RESTORATIVE DENTISTRY

Oral infectious diseases are probably the most common infectious pathologies affecting humankind. They have a significant impact on both people quality of life and costs for the healthcare system. Thus, their prevention should be high priority for governaments and research institutes. There are hundres of bacterial species in the oral environment, however, only a few of them are pathogenic. In fact, the disease begins when there is an imbalance in the oral biofilm with a prevalence of pathogenic species. In order to prevent oral infectious diseases we can eliminate most of the oral biofilm with mechanical and chemical means. However, in this way also many saprophytic species are eradicated. A smart solution could be to induce a selective pressure for \u201cgood\u201d oral bacteria thus hampering pathogenic ones. How can we achive this? Modifying our diet is a possible solution, we demonstrated how cariogenic biofilm development was lowered by using levorotatory carbohydrates instead of dextrorotatory ones. If we already have a carious lesion, it should be removed and the tooth restored with proper materials. However, most of them are methacrylate based and favour biofilm development, moreover, they also seem to select cariogenic species due to the lack of buffering ability. In our study we demonstrated how the use of different materials, the siloranes, could lead to a decrease in the biofilm development, thus theoretically lowering the incidence of secondary caries. If a tooth cannot be recovered and should be extracted, dental implants are probably the best solution for their replacement. However, peri-implantitis is a serious issue affecting up to 50% of the implant and can lead to their loss. The prevention of this oral disease is hence very important. In our study we compared different materials and showed that biofilm formation was similar in all of them. In future studies we will investigate if the biofilm on these materials is similar or not and if they are prevalently pathogenic or saprophytic ones. In conclusion, oral infectious disease are still very common and for decades dentists tried to achieve oral health by eliminating all the biofilm. However, the most innovative strategy is not to eradicate it but to induce selective pressures by using different means thus leading to a beneficial biofilm which does not cause illness but instead promote our health

Substituted nano-hydroxyapatite toothpastes reduce biofilm formation on enamel and resin-based composite surfaces

Background: Toothpastes containing nano-hydroxyapatite (n-HAp) substituted with metal ions provide calcium and phosphate ions to dental hard tissues, reducing demineralization, and promoting remineralization. Few data are available about the effect of these bioactive compounds on oral microbiota. Methods: This in vitro study evaluated the influence of two commercially-available substituted n-HAp-based toothpastes (\u3b1: Zn-carbonate substituted n-HAp; \u3b2: F, Mg, Sr-carbonate substituted n-HAp) on early colonization (EC, 12 h) and biofilm formation (BF, 24 h) by oral microbiota. Controls were brushed with distilled water. Artificial oral microcosm and Streptococcus mutans biofilms were developed using human enamel and a resin-based composite (RBC) as adherence surfaces. Two test setups, a shaking multiwell plate and a modified drip-flow reactor (MDFR), were used to simulate clinical conditions during the night (low salivary flow and clearance) and daytime, respectively. Energy-dispersive X-ray spectrometry (EDS) was used to evaluate specimens\u2019 surfaces after toothpaste treatment. Fluoride release from \u3b2 toothpaste was evaluated. Viable adherent biomass was quantified by MTT assay, and biofilms\u2019 morphology was highlighted using confocal microscopy. Results: EDS showed the presence of remnants from the tested toothpastes on both adherence surfaces. \u3b2 toothpaste showed significantly lower EC and BF compared to control using the artificial oral microcosm model, while \u3b1 toothpaste showed lower EC and BF compared to control, but higher EC and BF compared to \u3b2 toothpaste. The effect shown by \u3b2 toothpaste was, to a minimal extent, due to fluoride release. Interestingly, this result was seen on both adherence surfaces, meaning that the tested toothpastes significantly influenced EC and BF even on RBC surfaces. Furthermore, the effect of toothpaste treatments was higher after 12 h than 24 h, suggesting that toothbrushing twice a day is more effective than brushing once. Conclusions: The efficacy of these treatments in reducing microbial colonization of RBC surfaces may represent a promising possibility in the prevention of secondary caries

Biofilm formation on dental implant surface treated by implantoplasty : an in situ study

Peri-implantitis is a biofilm-related disease whose characteristics are peri-implant tissues inflammation and bone resorption. Some clinical trials report beneficial effects after implantoplasty, namely the surgical smoothening of the implant surface, but there is a lack of data about the development of the bacterial biofilm on those smoothened surfaces. The aim of this study is to evaluate how implantoplasty influences biofilm formation. Three implants with moderately rough surfaces (control) and three implants treated with implantoplasty (test) were set on a tray reproducing the supra- and sub-gingival environment. One volunteer wore this tray for five days. Every 24 h, plaque coverage was measured and, at the end of the period of observartion, the implant surfaces were analyzed using scanning electron microscopy and confocal laser scanning microscopy. The proportion of implant surface covered with plaque was 65% (SD = 7.07) of the control implants and 16% (SD = 0) of the test implants. Untreated surfaces showed mature, complex biofilm structures with wide morphological diversity, and treated surfaces did not show the formation of mature biofilm structures. This study supports the efficacy of implantoplasty in reducing plaque adhesion and influencing biofilm formation. These results can be considered a preliminary proof of concept, but they may encourage further studies about the effects of implantoplasty on biofilm formation

Age-related changes of the ocular surface : a hospital setting-based retrospective study

Purpose. To investigate the effects of age on the prevalence of ocular surface diseases (OSD), adherence to treatment, and recovery rates. Patients and Methods. Retrospective analysis of 3000 clinical records from a first-level general ophthalmology clinic. Patients with OSD were prospectively submitted a questionnaire to assess compliance and recovery rates. Results. OSD prevalence was 10.3%. Patients with OSD were significantly older than patients without it: 67.5 \ub1 20.3 versus 57.0 \ub1 22.0 years (P = 0.036). No significant difference in season distribution was shown. Dry eye disease (DED) represented 58% of OSD; its prevalence increased with age until 80 years old and suddenly decreased thereafter. Asymptomatic DED was 37%. Adherence to treatment in OSD was very high (94%); recovery rates were lower in patients aged 21-40 and 61-80 (resp., 65.5% and 77.8%) and this was associated with higher OSDI scores. Tear substitutes represented 50% of all prescribed medications; their use increased with age. Discussion. In a "reallife"low-tech setting, OSD showed a prevalence of 10.3%. DED was the most prevalent disease, and it was asymptomatic in more than 1/3 of cases

Laser microtextured titanium implant surfaces reduce in vitro and in situ oral biofilm formation

Introduction Micro- or nano-topography can both provide antimicrobial properties and improve osseointegration of dental implant titanium surfaces. Laser treatment is one of the best surface microtexturing techniques. The aim of this study was to evaluate in vitro and in situ biofilm formation on a laser-treated titanium surface, comparing it with two conventional surfaces, machined and grit-blasted. Methods For the in vitro experiment, an oral microcosm biofilm model was developed on the surface of titanium disks and reference human enamel using a bioreactor for 48 h. For the in situ experiment, titanium implants with laser-treated, machined and grit-blasted surfaces were mounted on intraoral trays and worn by ten volunteers for 48 h. Biofilm formation was quantitatively evaluated, and surfaces were analyzed using confocal laser scanning microscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy. Results\u2013in vitro study Biofilm structures with a prevalence of viable cells covered most of the machined, grit-blasted and human enamel surfaces, whereas less dense biofilm structures with non-confluent microcolonies were observed on the laser-treated titanium. Laser-treated titanium showed the lowest biofilm formation, where microorganisms colonized the edges of the laser-created pits, with very few or no biofilm formation observed inside the pits. Results\u2013in situ study The biofilm formation pattern observed was similar to that in the in vitro experiment. Confocal laser scanning microscopy showed complete coverage of the implant threads, with mostly viable cells in grit-blasted and machined specimens. Unexpectedly, laser-treated specimens showed few dead microbial cells colonizing the bottom of the threads, while an intense colonization was found on the threading sides. Conclusion This data suggests that laser-created microtopography can reduce biofilm formation, with a maximum effect when the surface is blasted orthogonally by the laser beam. In this sense the orientation of the laser beam seems to be relevant for the biological interaction with biofilms

Repeatability and reproducibility of applanation resonance tonometry : a cross-sectional study

Background: To assess repeatability (intra-observer variability) and reproducibility (inter-operator variability) of intraocular pressure (IOP) measurements with servo-controlled Bioresonator Applanation Resonance Tonometry (ART) and to evaluate possible influential factors. Methods: The study included 178 patients (115 glaucoma and 63 controls; one eye per subject). IOP was measured once with a Goldmann applanation tonometer (GAT) and twice by ART (ART1, ART2), in randomized sequence, by a single operator to assess intra-operator variability. Each ART measurement consisted on 3 readings. To assess inter-operator variability 2 evaluators performed 2 measurements each (in random order) on the same patient. Repeatability and reproducibility were assessed by the coefficient of variation (CoV) and intraclass correlation coefficient (ICC). Results: In the entire cohort, ART1 was 0.4 \ub1 2.2 mmHg (-7.0 to 5.7 mmHg) higher than ART2 (p = 0.03) regardless of test order. Intra-operator CoV was 7.0% \ub1 6.3%, and ICC was 0.80-0.92. Inter-operator CoV ranged between 5.7% \ub1 6.1% and 8.2% \ub1 7.2%, and ICC between 0.86 and 0.97. ART1 and 2 were respectively 1.7 \ub1 3.1 and 1.3 \ub1 3.1 mmHg higher than GAT (p < 0.01). Test-retest difference with ART fell within \ub11 mmHg in 41% of cases, within \ub12 mmHg in 70%, within \ub13 mmHg in 85%. 15% had a test-retest difference higher than \ub1 3 mmHg; Bland-Altman 95% intervals of confidence were -3.9 and +4.6 mmHg. Results were unaffected by age, diagnosis, central corneal thickness, keratometry, operator, randomization sequence. Conclusions: In most cases ART repeatability and reproducibility were high, with no differences due to patients' characteristics. ART measurements overestimated GAT by a mean of 1.3-1.7 mmHg

Nuovi materiali odontoiatrici da restauro a effetto antimicrobico = New dental restorative materials featuring antimicrobial activity

Obiettivi. Il presente lavoro si propone di fornire una panoramica sugli approcci al problema dell\u2019interazione tra i nuovi materiali utilizzati in odontoiatria restaurativa e il biofilm microbico orale. Materiali e metodi. Un inquadramento del problema della carie secondaria, dei biofilm orali, delle loro interazioni con i materiali da restauro viene proposto grazie a una revisione della letteratura. Risultati. Lo sviluppo di materiali bioattivi pu\uf2 prevedere la presenza di inibizione da contatto dei batteri orali, oppure il rilascio di agenti antimicrobici. Altri approcci prevedono l\u2019ottimizzazione delle superfici di materiali gi\ue0 esistenti per migliorare le loro propriet\ue0 microbiologiche. Un ulteriore approccio, infine, prevede la sintesi di materiali biomimetici, ovvero di materiali che dal punto di vista meccanico, biologico e microbiologico si comportano in maniera simile ai tessuti dentali che sostituiscono. Conclusioni. Ciascuno degli approcci sopracitati presenta vantaggi e svantaggi e a oggi non esiste un materiale che soddisfi appieno le richieste cliniche. Le generazioni di materiali a venire saranno caratterizzate dalla presenza di bioattivit\ue0, cio\ue8 dalla capacit\ue0 del materiale di interfacciarsi in maniera positiva sia con i tessuti dell\u2019ospite sia con il biofilm che lo colonizza.Objectives. This dossier aims to provide a modern overview on how to approach the interactions between new restorative materials and oral biofilms. Materials and methods. A literature review on secondary caries, oral biofilms and their interactions with restorative materials is shortly presented. Results. The development of bioactive materials can involve contact-inhibition of oral bacteria, or the release of antimicrobial agents. Other approaches focus on surface optimization of already existing materials to enhance their microbiological behaviour. An additional approach deals with the synthesis of biomimetic materials, namely materials behaving similarly to dental tissues, as they are able to replace them from a mechanical, biological and microbiological point of view. Conclusions. Each approach has pros and cons, and to date no material has proven to fully meet all clinical demands. New generations of materials yet to come will presumably be characterized by the presence of bioactivity, that is the ability of a material to actively and positively interact both with the host tissues and with the colonizing biofilm

Influence of light-curing parameters on biofilm development and flexural strength of a silorane-based composite

Objectives: The aim of this study was to evaluate the differences in biological and mechanical performances of a silorane-based and a methacrylate-based composite. Another aim was to assess the influence of light-curing time and light-curing intensity on in vitro biofilm formation and flexural strength of the two tested composites. Methods: Experiment 1: 432 specimens obtained from a silorane-based composite and from a standard methacrylate-based composite were divided into six groups and light-cured for 10, 20, 30, 40, 60, or 80 seconds, using one of two light-curing intensities, 400 mW/cm2 or 800 mW/cm2. At 24 hours, a monospecific Streptococcus mutans biofilm adherent to the surfaces of the samples was obtained. Then, a colorimetric technique (MTT assay) was used to evaluate the adherent viable biomass. Two samples per group were observed using confocal laser scanning microscopy. Analysis of variance ANOVA) and Tukey tests were used to analyze the results (p,0.05). Experiment 2: 192 bar-shaped specimens were obtained and light-cured as in the previous experiment. A three-point bend test using a universal testing machine was performed to obtain flexural strength values. ANOVA and Tukey tests were used to analyze the results (p,0.05). Results: In experiment 1, a highly significant difference (p,0.0001) in biofilm development was shown between silorane-based and methacrylate-based composites. In fact, the silorane-based composite exhibited better biological performance. Significant differences were also found between the two light-curing intensities (p,0.018) and for curing times (p,0.0001): silorane-based composite light-cured for 80 seconds at 800 mW/cm2 light-curing intensity showed the lowest biofilm development. In experiment 2, a significant difference in flexural strength (p,0.0318) was only found between the different composites. Nevertheless, both resin composites showed flexural strength values in accordance with International Organization for Standardization guidelines even after 10 seconds of light-curing time. Conclusions: Silorane-based composite was less prone to biofilm development compared with a methacrylate-based composite. Acceptable flexural strength values for both composites were obtained after 10 seconds of lightcuring time