Effects of proanthocyanidin-functionalized hydroxyapatite nanoparticles on dentin bonding.

OBJECTIVES: To evaluate the effect of proanthocyanidin-functionalized hydroxyapatite nanoparticles (nHAp_PA) used as pretreatment at different concentrations on the microtensile bond strength (µTBS) and endogenous enzymatic activity (MMPs) on pH-cycled dentin after 24 h and 6 months of artificial aging. MATERIALS AND METHODS: Fifty human sound dentin blocks were randomly assigned to 5 groups (n = 10): (i) negative control (no treatment); (ii) positive control (pH-cycling); (iii) pH-cycling + 2% nHAp_PA for 60s; (iv) pH-cycling + 6.5% nHAp_PA for 60s; (v) pH-cycling + 15% nHAp_PA for 60s. A self-etch adhesive was used for bonding procedures before resin composite build-ups. Specimens were tested with the µTBS test after 24 h and 6 months of laboratory storage. The proteolytic activity in each group was evaluated with gelatin zymography and in situ zymography. Data were statistically analyzed (p < 0.05). RESULTS: At 24 h, the µTBS of the experimental groups were significantly higher than the controls (p ≤ 0.001), and no differences were observed between different concentrations (p > 0.05). Artificial aging significantly decreased bond strength in all groups (p ≤ 0.008); however, nHAp_PA 2% still yielded higher bonding values than controls (p ≤ 0.007). The groups pretreated with nHAp_PA exhibited lower MMP-9 and MMP-2 activities compared to the positive control group and almost the same enzymatic activity as the negative control group. In situ zymography showed that after 6 months of aging, nHAp_PA 2% and nHAp_PA 6,5% decreased enzymatic activity as well as the negative control. CONCLUSIONS: Dentin pretreatment with nHAp_PA increased the bonding performance of a self-etch adhesive and decreased MMP-2 and MMP-9 activities after 6 months.

Color match of single-shade restorations after professional dental bleaching: An in vitro study.

Background: Restorative dentistry aims to reproduce natural tooth shades through resin composites that must be layered to obtain colors, opacities, and translucencies, and therefore, clinical success is operator skill dependent. Aims: The purpose of this study is to evaluate the color shift of single-shade composite restorations before and after dental bleaching. Materials and Methods: Eighty human extracted posterior teeth were restored with four single-shade composites (Omnichroma OM; Clearfil Majesty ES-2 Universal CL; Essentia Universal ES; Venus Diamond One VE) (n = 20 each). Standardized V class cavities were prepared on buccal side. VITA Easyshade V spectrophotometer was used to register VITA color and color coordinates 24 h before (T0), 24 h after (T1), and 1 week after (T2) dental bleaching (Opalescence Boost PF 40%). Color differences (ΔEab) and (ΔWID) were calculated and subjected to statistical analysis. Statistical Analysis: Categorical variables were analyzed using Pearson Chi-square, and data from color coordinates were analyzed using one-way analysis of variance and Tukey's multiple comparison test with Bonferroni correction. Paired t-tests were performed to compare continuous measures between groups and treatment time. Results: Instrumental evaluations revealed statistically significant differences between materials (P < 0.05) with lower values for ES and VE samples followed by CL and OM at T0 and T1. At T2, OM and CL ΔEab values decrease getting closer to ES and VE. Conclusion: Single-shade composites seem to match with the surrounding bleached tooth.

Comparisons of ammonia- and water-based silver-containing solutions on dentin bonding and enzymatic activity: 1-yr evaluation.

OBJECTIVE: To evaluate the effects of an ammonia-based and a water-based silver-containing solutions on bonding performance and matrix-metalloproteinases (MMPs) activity of a universal adhesive to dentin after 1 year of artificial aging. METHODS: Mid-coronal dentin surfaces of 60 sound human molars were exposed and the following groups were formed according to the surface pre-treatment and etching mode of the universal adhesive (Zipbond Universal, SDI) (n = 10): G1) Zipbond in the self-etch mode (ZSE); G2) Riva Star (SDI) applied before ZSE; G3) Riva Star Aqua (SDI) applied before ZSE; G4) Zipbond in the etch-and-rinse mode (ZER); G5) Riva Star applied before ZER; G6) Riva Star Aqua applied before ZER. The specimens were sectioned and subjected to microtensile bond strength (µTBS) test at baseline (T0) and after 12 months (T12) of artificial storage. Scanning electron microscope (SEM) and energy dispersive spectroscopy analysis (EDS) were also conducted. Three additional molars per group were processed for the in situ zymography analysis at T0 and T12. Data were statistically analyzed (p < 0.05). RESULTS: Dentin pre-treatments and aging decreased bonding values, regardless of the etching mode (p < 0.05). No differences in µTBS were observed between the two silver-containing solutions, both at T0 and T12. Riva Star Aqua and etching significantly increased the MMPs activity, independent of the storage period (p < 0.05). SIGNIFICANCE: Dentin surface pre-treatment with silver-containing solutions negatively affects the bonding performances of resin composite restorations placed with a universal adhesive. However, the ammonia-based product Riva Star might show better stability in the long term, due to lower activation of MMPs.

Changes in Oral Health and Dental Esthetic in Smokers Switching to Combustion-Free Nicotine Alternatives: Protocol for a Multicenter and Prospective Randomized Controlled Trial.

BACKGROUND: Although the detrimental effects of conventional combustible cigarettes on oral health and dental esthetics are well known, there is limited information about the long-term impact of combustion-free nicotine alternatives (C-F NA) such as e-cigarettes or heated tobacco products. OBJECTIVE: This multicenter, prospective, 3-parallel-arm randomized controlled trial will investigate whether switching from combustible cigarettes to C-F NA will lead to measurable improvements in oral health parameters and dental esthetics over 18 months in adult smokers with limited gum disease. METHODS: Regular smokers not intending to quit and without clinical signs of periodontitis will be randomly assigned (1:4 ratio) to either standard of care with brief cessation advice (control group; arm A) or C-F NA use (intervention group; arm B). The study will also include a reference group of never smokers (reference group; arm C). The primary end point is the change in the Modified Gingival Index (MGI) score from baseline between the control arm (arm A) and the intervention arm (arm B) at the 18-month follow-up. In addition, the study will analyze the within- and between-group (arms A, B, and C) changes in MGI assessment, plaque imaging, dental shade quantitation, tooth stain scores, and oral health-related quality of life questionnaires measured at each study time point. All participants will attend a total of 7 clinic visits: screening, enrollment, and randomization (visit 0); baseline visit-day 14 (visit 1); day 90 (visit 2); day 180 (visit 3); day 360 (visit 4); and day 540 (visit 5). This multicenter study will be conducted in 4 dental clinics in 4 countries. The statistical analysis will involve descriptive statistics for continuous and categorical data. Primary end points will undergo tests for normality and, based on distribution, either a 2-sided t test or Mann-Whitney U test. Linear mixed model with random factors center and study arms by center will also be applied. Secondary end points, including MGI assessment and quality of life, will be subjected to similar tests and comparisons. Only if one value of the parameter MGI is missing after day 1, the last available observation will be carried forward. The analysis will be performed on the substituted data. Secondary parameters will not have missing value replacement. RESULTS: Participant recruitment began in October 2021, and enrollment was completed in June 2023. Results will be reported in 2025. CONCLUSIONS: This will be the first study to provide key insights into oral health benefits or risks associated with using C-F NA in smokers who are seeking alternatives to cigarette smoking. TRIAL REGISTRATION: ClinicalTrials.gov NCT04649645; https://clinicaltrials.gov/ct2/show/NCT04649645. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/53222.

Push-out bond strength and SEM fractographical analysis of hollow fibre posts used with self-adhesive resin cement: a pilot study.

Detachment is the major cause of failure of endodontic fibre posts. Hollow posts have been recently introduced to overcome such issue. The primary aim of this pilot study was to compare the push-out bond strength of hollow posts and traditional solid posts. Eight round-shaped single-canal premolars extracted for periodontal reason were selected as sample and equally randomized into two groups: (i) traditional solid fibre posts-TECH21xop and ii) hollow fibre posts-TECHOLE. A dual-curing self-adhesive cement (new TECHCEM) was used for posts placement. Six horizontal sections-two from each portion of the root (coronal, middle and apical)-were obtained from each sample root, yielding a total of 24 sections for each group. Push-out test was performed on the sections and bond strength values were compared between groups and within each group. Scanning electron microscope (SEM) fractographical analysis was conducted on each section. Additional SEM and EDX analyses were performed on new samples of both posts, to assess fibres density and distribution, and the chemical composition of the fibres and the matrix. Hollow posts showed a significantly higher push-out bond strength (6.36 ± 1.22 MPa) than solid posts (3.64 ± 1.62 MPa). Among the three root portions of the same group, there was no significant difference in bond strength. In both groups, the most frequent type of fracture was a mixed adhesive failure with the cement covering 0 to 50% of the post perimeter. Hollow post fibres appear more similar in size and have a more homogeneous distribution, compared to solid posts. The two post types also have different chemical compositions.

Effect of bleaching on the color match of single-shade resin composites.

PURPOSE: To evaluate the color match of single-shade resin composites before and after bleaching procedures, through instrumental and visual analyses. METHODS: Class V cavities were created on the buccal surfaces of 80 extracted human molars, restored with 4 single-shade composites (Omnichroma; Clearfil Majesty ES-2 Universal; Essentia Universal; Venus Diamond One). A spectrophotometer (VITA Easyshade V) was used to evaluate the tooth/resin color match before (T0), and 24 h (T1) and one week (T2) after dental bleaching (Opalescence Boost PF 40%). Color variations (ΔE00) were calculated and statistically analyzed (P < 0.05). Visual analysis was performed before and after tooth bleaching. RESULTS: Spectrophotometric evaluations revealed statistically significant differences between materials at T0, T1, and T2 (P < 0.05). Visual analysis reported excellent and very good grades (0 and 1, respectively), irrespective of the materials and timepoints. CONCLUSION: Data seem to indicate that single shade composites are able to shift their color when the surrounding tooth undergoes bleaching effects. Single-shade composites seem to achieve a good color match with the surrounding tooth structure, before and after professional bleaching.

Glutaraldehyde-based desensitizers' influence on bonding performances and dentin enzymatic activity of universal adhesives.

OBJECTIVES: To evaluate the influence of two glutaraldehyde-based desensitizers (L: GLUMA Desensitizer, Heraeus Kulzer and G: GLUMA Desensitizer PowerGel) prior to the adhesive procedures on microtensile bond strength (µTBS) to dentin and endogenous enzymatic activity. METHODS: Noncarious human third molars (N = 48) were cut to expose middle coronal dentin. Six experimental groups were formed according to the dentin pre-treatment (L or G) and the universal adhesives (IBU - iBond universal, Kulzer or AU - Adhese Universal, Ivoclar Vivadent) used in the self-etch mode (n = 8): 1) L/IBU; 2) G/IBU; 3) IBU; 4) L/AU; 5) G/AU; 6) AU. Specimens were cut into sticks and stressed until failure after 24 h (T0) or 1 yr of aging (T12). Additional 4 teeth were used for in situ zymography evaluation and data were statistically analyzed (α = 0.05). RESULTS: Dentin pre-treatment, adhesive and aging statistically influenced bond strength and enzymatic activity (P<0.001). AU demonstrated higher bond strength values than IBU (P<0.001). The L resulted in higher bond strength compared to the G and control groups (P<0.001). aging statistically influenced bonding performance, especially when no dentin pre-treatment was performed (P<0.001). In situ zymography revealed that at baseline the control groups exhibited lower interfacial fluorescence compared to the experimental groups, irrespective of the adhesive used (P<0,001). However, after 1 yr of artificial storage, no differences were found among the groups (P>0.05). CONCLUSIONS: Glutharldeadeyde-based products increased bond strength and determined a stabilization of the adhesive interface over time apparently not related to the MMPs inhibition. CLINICAL SIGNIFICANCE: The results of this in vitro study suggest that the application of glutaraldehyde-based desensitizers prior to the adhesive procedures when associated with universal adhesives could result in increased bond strength and stabilization of the adhesive interface over time.

Shaping ability of Procodile and R6 Reziflow nickel-titanium reciprocating instruments in curved mesial root canals of mandibular molars: A MicroCT study.

To compare the shaping ability of Procodile and R6 Reziflow instruments used in reciprocating motion in severely curved root canals, assessed with micro-computed tomography (µCT). Fourteen extracted human mandibular first molars were randomly assigned to two instrumentation techniques (n = 14 mesial root canals): Procodile or R6 Reziflow. For both groups, root canals were prepared to the working length up to a size 25, .06 taper. Molars were virtually divided into apical, middle and coronal thirds and µCT was used to scan all samples pre- and post-root canal. Canal transportation, centring ability, volume, surface area and unprepared area were evaluated. Geometrical parameter changes were compared with preoperative values (one-way analyses of variance and Tukey multiple comparison post-hoc test) between groups and Student t-test within groups (α = 0.05) Significantly less transportation was observed associated with the Procodile technique in the molar's coronal third compared to the R6 Reziflow technique (p < .05). No significant differences in root canal centring ability, volume, surface area and unprepared area were observed. Procodile showed a lower percentage increase of surface area compared to R6 Reziflow (p < .05). The Procodile and R6 Reziflow techniques applied to first molar root canal performed similarly except for the less transportation observed in the coronal third using Procodile. RESEARCH HIGHLIGHTS: MicroCT analysis of canal geometry before and after instrumentation revealed that Procodile and R6 Reziflow showed a similar shaping ability to shape curved root canals without substantially modifications of the original tooth anatomy.

Effect of adhesive strategy on resin cement bonding to dentin.

OBJECTIVE: The cement bonding strategy and the polymerization mode can influence the prognosis of indirect restorations. The microtensile bond strength (µTBS) and dentin endogenous enzymatic activity of a dual-cure resin cement (PV5) used in combination with two dentin surface conditioners (accelerator-enhancer primer, TP or universal adhesive, UA) were evaluated. MATERIALS AND METHODS: PV5 was used to lute composite overlays after dentin treatment with TP or UA. The resin cement was self-cured, SC (1 h at 37 °C) or dual-cured, DC (20 s light-cure followed by 15 min self-cure at 37°C). The µTBS test, fractographic analysis, and the in situ zymography evaluations were performed after 24 h (T0 ) or 1 yr (T12 ) of artificial storage. Data were statistically analyzed (α = 0.05). RESULTS: TP/DC obtained the highest adhesive strengths (45 ± 9 and 36.6 ± 8), while UA/SC (17 ± 8 and 11 ± 4) the lowest, both at T0 and T12 , respectively. DC resulted in superior bonding values than the SC, independent of the dentin surface treatment (p < 0.05). The type of adhesive, curing mode and aging influenced the gelatinolytic activity (p < 0.05). CONCLUSIONS: The dual-cure resin cement used in combination with its accelerator-enhancer primer showed superior bonding performances with respect to universal adhesive. Dual-curing the resin cement was determinant to enhance bonding capability over time, independent of the adhesive strategy. CLINICAL RELEVANCE: Clinicians must be aware to faithfully follow manufacturer's recommendation regarding the adhesive strategy suggested with the resin cement used.

Bone Modeling after Orthodontic Extrusion: A Histomorphometric Pilot Study.

During osteogenesis and bone modeling, high vascularity and osteoblastic/osteoclastic cell activity have been detected. A decrease in this activity is a sign of complete bone formation and maturation. Alveolar bone maturation seems to occur within weeks and months; however, the precise timing of the alveolar bone modeling is still unknown. The aim of this clinical pilot study was to investigate the bone modeling of neo-apposed tissue during orthodontic extrusive movements, through a histomorphometric analysis of human biopsies. This study was conducted on third mandibular molars sockets, and all teeth were extracted after orthodontic extrusion between 2010 and 2014. After different stabilization timings, extractions were performed, and a specimen of neo-deposed bone was harvested from each socket for the histomorphometric analysis. Histological parameters were evaluated to identify bone quantity and quality. This study included 12 teeth extracted from 9 patients. All specimens were composed of bone tissue. Bone samples taken after 1 and 1.5 months of stabilization presented remarkable percentages of woven bone, while after 2 months, a relevant decrease was observed. Histomorphometric analysis suggested that after orthodontic extrusion, a period of stabilization of 2 months allows the neo-deposed bone to mature.

Bioburden Variation of Filtering Face Piece Respirators over Time: A Preliminary Study.

BACKGROUND: The microbial contamination of a respirator can be evaluated through a count of the number of bacteria living on a non-sterilized surface (bioburden). This preliminary study investigated the external contamination of two different FFP2s over time by studying the bioburden values in increasing exposure times. METHODS: FFP2 respirators of two different brands were used during routine clinical settings and examined through the bioburden test; for each brand, three devices were tested at 8, 16, and 30 h. RESULTS: No significant differences were observed between mask brands (p = 0.113). There were only significant CFU differences between each mask and its control (p = 0.027 and p = 0.004). CONCLUSIONS: Both brands of respirators were found to be contaminated and this contamination increased with the increase in exposure time. Further studies are needed to investigate the exact amount of contamination that could be considered acceptable before discarding each used mask.

Can a single molar root act as a whole tooth?

This clinical case describes the longitudinal outcome of a radisected upper molar root. The palatal root acted as an abutment and was finalized with a double-premolar-shaped metal-resin crown with two rests on the adjacent teeth. Fifteen years later, the root and its crown were still in place, with no pathologic pocket probing depth and lack of inflammation; the tooth was still in function with no signs of periodontal breakdown. This therapeutic option seemed to have been biologically respectful and maintains the possibility to provide future implant therapy.

Recognition and treatment of peri-implant mucositis: Do we have the right perception? A structured review.

Peri-implant mucositis is a common inflammatory lesion of the soft tissues surrounding endosseous implants, with no loss of the supporting bone. Its prevention or early diagnosis are vital for dental implant success.The aim of this review was to investigate knowledge strengths and gaps in clinicians' perceptions of periimplant mucositis prevalence and evidence for successful treatment.A literature search for articles published until 2020, reporting on the prevalence of peri-implant mucositis and its treatment was performed in standard online databases. The inclusion criteria were as follows: studies in English; studies with an available abstract; studies on humans with at least 1 dental implant; and studies reporting on the prevalence and/or treatment of peri-implant mucositis. Sixty-five studies fulfilled the inclusion criteria. The included papers were analyzed to identify data on the prevalence and treatment of peri-implant mucositis. The prevalence statistics for peri-implant mucositis had wide ranges in both the patient-based (PB) analysis and the implant-based (IB) analysis; the possible reasons for these wide ranges are discussed. Treatment methods for peri-implant mucositis were analyzed individually and compared to the management of gingivitis.It was determined that the currently available information on the prevalence rates and the standardized therapeutic protocols for peri-implant mucositis are insufficient. Since the mean gingivitis and peri-implant mucositis prevalence rates in the PB analysis were similar, it is possible that peri-implant mucositis is underestimated due to variables related to implant rehabilitation itself.

Comparative Evaluation of the Penetration Depth into Dentinal Tubules of Three Endodontic Irrigants.

This study aimed to examine the penetration depth into dentinal tubules of some chelating agents. The 17% EDTA and two preparations containing surfactants (Smear Clear, Bioakt Endo) were tested. Surface tension and liquid viscosity were measured using a Dynamic Contact Angle Analyzer and a Haake rotational rheometer. To measure the penetration depth inside dentinal tubules, thirty maxillary central incisors were selected from a pool of extracted human permanent teeth and allocated to three experimental groups (10 samples each), as well as were mechanically shaped and cleansed with 5.25% NaOCl, followed by each of the chelators being labeled with 0.1 wt % Rhodamine B according to final irrigation protocol established. The samples were embedded in an epoxy resin, after which 200 µm thick transverse sections were obtained at 2, 5, and 8 mm from the apex with a saw microtome. The specimens were then observed using a confocal laser microscope (CLSM) and the penetration of the labeled solution was measured in every third of each sample. Statistical analysis was performed using ANOVA or Kruskal-Wallis tests according to the distribution of data, evaluated with the Shapiro-Wilk normality test. Viscosity and surface tension tests have shown that BioAKT Endo has the lowest values compared to EDTA and Smear Clear. The medium penetration depth did not significantly differ among the three irrigants, while it increased considerably from the apical to the coronal level in all groups. Additionally, the maximum penetration depth increased significantly from the apical to coronal level, while among groups, BioAKT Endo showed the highest values at the apical and middle level compared to the other irrigants. No significant differences were observed among the three groups in medium and maximum penetration depths when the entire root was considered. New irrigants containing surfactants show reduced surface tension and, in one case (BioAKT Endo), viscosity. The lowering of the surface tension allows for better penetration of liquids into dentinal tubules than EDTA alone, thus improving the cleaning of the root canal system.

Endogenous Enzymatic Activity in Dentin Treated with a Chitosan Primer.

The aim of this study was to evaluate the effect of different concentrations of chitosan polymer on dentinal enzymatic activity by means of gelatin and in situ zymography. Human dentin was frozen and ground in a miller. Dentin powder aliquots were demineralized with phosphoric acid and treated with three different concentrations of lyophilized chitosan polymer (1, 0.5 and 0.1 wt%) dissolved in distilled water. Dentin proteins were extracted from each experimental group and electrophoresed under non-reducing conditions in 10% SDS-PAGE containing fluorescein-labeled gelatin. After 48 h in the incubation buffer at 37 °C, proteolytic activity was registered under long-wave UV light scanner and quantified by using Image J software. Furthermore, additional teeth (n = 4) were prepared for the in situ zymographic analysis in unrestored as well as restored dentin pretreated with the same chitosan primers. The registered enzymatic activity was directly proportional to the chitosan concentration and higher in the restored dentin groups (p < 0.05), except for the 0.1% chitosan primer. Chitosan 0.1% only showed faint expression of enzymatic activity compared to 1% and 0.5% concentrations. Chitosan 0.1% dissolved in water can produce significant reduction in MMPs activity and could possibly contribute to bond strength preservation over time.

Endogenous Enzymatic Activity of Primary and Permanent Dentine.

Matrix metalloproteinases (MMPs) play an important role in tooth development and influence caries development and hybrid layer degradation. Literature is scant on the differences in the activity of MMPs between primary and permanent dentine. Accordingly, the aim of the present study was to investigate endogenous gelatinolytic activity in primary and permanent dentine. Separate batches of dentine powder were obtained from intact human primary and permanent molars (n = 6). Each batch was divided in two subgroups: (1) mineralised; and (2) demineralised with 10% H3PO4. After protein extraction, gelatine zymography was performed. Furthermore, in situ zymography was performed on dentine sections of the same groups (n = 3). The slices were polished, covered with fluorescein-conjugated gelatine and evaluated using a confocal microscope. In situ zymography data were analysed using two-way analysis of variance and post hoc Holm-Sidák statistics (α = 0.05). Primary dentine showed poorly defined bands in the zymograms that vaguely corresponded to the pro-form and active form of MMP-2 and the pro-form of MMP-9. In permanent dentine, demineralised powder demonstrated stronger gelatinolytic activity than mineralised powder. In situ zymography identified stronger enzymatic activity in primary etched dentine (p < 0.05). Stronger enzymatic activity recorded in primary dentine may be related to the differences in morphology and composition between primary and permanent dentine.

Traumatic Dental Injuries: Clinical Case Presentation and a 10-Year Epidemiological Investigation in an Italian Dental Emergency Service.

Traumatic dental injuries (TDIs) are very common in the world population, and international literature reports several studies which helped in the definition of international guidelines. The aim of this study is to present two clinical cases of TDI and to investigate epidemiological and etiological aspects of TDIs in patients treated in Modena, Italy, between January 2010 and December 2020. The presented case reports are two explicative clinical cases of successful TDI management with a long-term follow-up. The epidemiological analysis was performed on patients who visited the Dental Emergency Service of the Dentistry and Oral-Maxillo-Facial Surgery Unit of Modena (Italy) over a period of 10 years. Data relating to age, gender, type of trauma, and place of accident were collected. Five-hundred-sixty-five TDIs that occurred to patients from 1 to 68 years old were reported, with a total of 860 injured teeth. The peak age at which TDIs are most represented varies between 2 and 3 years old, and they occurred frequently from 1 up to 7 years old. 57.5% were male, while 42.5% were female. The most common trauma resulted to be the uncomplicated crown fracture (20%), immediately followed by lateral luxation (19%), intrusive luxation (18%), avulsion (17%), and complicated crown fracture (15%). TDIs occurred at home in 44% of cases. The need for more prevention training must be highlighted, due to the fact that many TDIs occur at home and in a preschool age.

Variation of Efficacy of Filtering Face Pieces Respirators over Time in a Dental Setting: A Pilot Study.

Since aerosol continuously persists in dental settings, where different procedures and patients come in succession, the use of oronasal masks is highly recommended. Among them, respirators known as Filtering Face Pieces (FFP) show a protective superiority compared to surgical masks. Even concerning respirators classified as non-reusable, it is not known how many hours of use are necessary to compromise their filtering capacity. The aim of this study is to investigate the variations of filtering capacity of an FFP2 respirator over time, in order to safely optimize the timing of its use. Five respirators were worn by the same operator during clinical activity for different usage times (8, 16, 24, 32, 40 h), and one respirator was kept unused. All respirators underwent a bacterial filtration efficacy (BFE) test. T-test for paired data with Bootstrap technique and Wilcoxon test for paired data compared BFE values of the five tested FFP2s respectively at each time, and the areas with the corresponding values of the control respirator (FFp2-F). A generalized linear mixed effect model (GLM) was applied considering type of respirator and time as fixed effects and intercept as random effect. No significant statistical differences were present in the BFE of each time. Data obtained by the present study highlight the important ability of FFP2s to maintain their BFE over time, suggesting a long lasting protective function.

Histologic Observations of Two Dental Implants Retrieved After Osseointegration.

This study aimed to histologically analyze the bony tissue formed around dental implants after osseointegration. A 58-year-old patient presented with pain and discomfort caused by two dental implants in her maxilla placed 8 months earlier. At clinical and radiographic analysis, the implants appeared well osseointegrated but tilted buccally, emerging in nonkeratinized mucosa. For this reason, the discomfort began right after the prosthetic load, 4 months after implant placement, and the patient felt pain when wearing the implant-supported removable prosthesis. Both implants were made of titanium, airborne-particle abraded with zirconium oxide, and etched with mineral acids. The implants were removed, preserving the bone around the implant threads, and replaced with two new implants, inserted in a prosthetically guided, correct position. The removed implants were histologically observed. Histologic analysis showed good bone-to-implant contact, mature bone with few marrow spaces, presence of direct connecting bridges between the peri-implant bone trabeculae and the implant surface, and no inflammatory cells nor connective fibrous tissue ingrowth. This study showed that dental implants coated with a rough surface were properly osseointegrated, with no inflammatory signs nor connective fibrous tissue ingrowth, 8 months after placement.

COVID-19 Dentistry-Related Aspects: A Literature Overview.

A new coronavirus (Sars-CoV-2) was detected in China at the end of 2019 and has since caused a worldwide pandemic. This virus is responsible for an acute respiratory syndrome (COVID-19), distinguished by a potentially lethal interstitial bilateral pneumonia. Because Sars-CoV-2 is highly infective through airborne contamination, the high infection risk in the dental environment is a serious problem for both professional practitioners and patients. This literature overview provides a description of the clinical aspects of COVID-19 and its transmission, while supplying valuable information regarding protection and prevention measures.