Low- and high-viscosity bulk-fill resin composites: a comparison of microhardness, microtensile bond strength, and fracture strength in restored molars

The aim of this study was to compare low- and high-viscosity bulk-fill composites for Knoop microhardness (KHN), microtensile bond strength (MTBS) to dentin in occlusal cavities, and fracture strength (FS) in molars with mesialocclusal-distal restoration. Disk-shaped samples with different thicknesses (2 or 4 mm) of low-viscosity (SDR Flow, Dentsply) and high-viscosity bulk-fill composites (Filtek BulkFill, 3M ESPE; and Tetric-N Ceram Bulk Fill, Ivoclar Vivadent) were prepared for top and bottom KHN analysis (n=10). MTBS to dentin and fracture pattern was evaluated in human molars with occlusal cavities restored with (n=10): conventional nanocomposite (Z350XT, 3M ESPE), low-viscosity (Filtek Bulk-fill Flow, 3M ESPE) or high-viscosity bulk-fill composites (Filtek BulkFill). The FS and fracture pattern of human molar with mesial-occlusal-distal restorations submitted or not to thermomechanical cycling were investigated (n=10) using: intact tooth (control), and restoration based on conventional microhybrid composite (Z250, 3M ESPE), low-viscosity (SDR Flow) or high-viscosity bulk-fill composites (Filtek BulkFill). The data were submitted to split-plot ANOVA (KHN), one-way ANOVA (MTBS), two-way ANOVA (FS) followed by Tukey’s test (α=0.05). For KHN, there was no significant difference for the resin composites between the top and bottom. For MTBS, no significant differences among the materials were detected; however, the low-viscosity composite presented lower frequency of adhesive failures. For FS, there was no significant difference between composites and intact tooth regardless of thermomechanical cycling. Low- and high-viscosity bulk-fill composites have comparable microhardness and microtensile bond strength when used in occlusal restorations. Likewise, the bulk-fill composites present similar fracture strength in molars with mesio-occlusal-distal restorations.

Anacardium excelsum phytochemical analysis and in vitro antimicrobial activity against oral cavity microorganisms

Infections of the oral cavity have a broad microbial etiological profile that varies according to each microenvironment in the mouth. Such infections often require antimicrobial treatment, which can lead to the development of resistance. There is thus a need to find new therapeutic strategies based on natural plant-derived compounds. The aim of this study was to determine the phytochemical nuclei and the antimicrobial effect of Anacardium excelsum leaf and stem extracts, and of fractions derived from the leaf extract, against Streptococcus mutans ATCC 25175, Staphylococcus aureus ATCC 35548, Escherichia coli ATCC 25922, Enterococcus faecalis ATCC 19433 and Candida albicans ATCC 10231. The plant material was collected from the Quindío Botanical Garden (Calarcá, Quindío-Colombia), located at an altitude of 1500 meters above sea level. Hydroalcoholic extracts of A. excelsum leaves and stems, and fractions of the hydroalcoholic leaf extract, were obtained by percolation extraction. Phytochemical nuclei were identified by thin layer chromatography. The antimicrobial activity of the extracts and fractions (at concentrations of 2, 5, 10, 20 and 40 mg / ml) against the five ATCC reference strains was evaluated using the well diffusion technique on Mueller-Hinton agar. The leaf extract showed no antimicrobial activity against E. coli, but it did show antimicrobial activity against S. mutans, S. aureus, E. faecalis and C. albicans, at a concentration of 10 mg/ml, with zones of inhibition of 9 to 11 mm. The ethyl acetate and acetone fractions obtained from A. excelsum leaf extract had greatest antimicrobial activity at 10 mg/ml. In conclusion, (1) the A. excelsum leaf extract, and the ethyl acetate and acetone fractions obtained from the leaf extract, had the greatest antimicrobial activity on all the study microorganisms, and (2) the phytochemical nuclei in the fractions (ethyl acetate and acetone) were found to contain phenolic-type compounds, tannins, triterpene-type terpenes and steroidal-type terpenes, which might explain the antimicrobial activity observed.

Anxiety about dental treatment – a gender issue

This study compared prevalence and risk factors of dental anxiety between men and women. The sample consisted of 244 participants (n = 122 men) aged 18 years or older who sought dental care at a public Dental Education Institution from March 2018 to November 2019. The Modified Dental Anxiety Scale was used to determine presence of dental anxiety. The following risk factors were recorded: age, years of schooling, preoperative pain, and type of dental treatment. Bivariate analysis was used to assess the difference in dental anxiety between the sexes. Multivariate logistic regression was used to analyze the association between dental anxiety and gender, regardless of the influence of other variables. Total prevalence of dental anxiety was 18% (n = 44), 22.9% (28/122) in women and 13.1% (16/122) in men (p = 0.04). Gender (odds ratio: 1.83, 95% confidence interval: 0.92–3.62) and preoperative pain (odds ratio: 2.095, 95% confidence interval: 0.97–4.49) were associated with dental anxiety. We concluded that women had a higher prevalence of dental anxiety. Preoperative pain was associated with dental anxiety regardless of gender.

Clinical evaluation of root coverage using coronally positioned flap associated with acellular dermal matrix allograft in single-type recession defects. A retrospective study

The aim of this study was to conduct a retrospective assessment of the clinical results at 6,12 and 24 months of root coverage in single gingival recessions using coronally positioned flap and acellular dermal matrix allograft. Clinical records were collected from 16 patients with single gingival recessions who visited a private practice in Periodontics in 2005 and 2006. They were treated through a coronally positioned flap and acellular dermal matrix allograft. The following periodontal parameters were recorded at baseline, 6, 12 and 24 months: Recession Depth, Recession Width, Probing Depth, Clinical Attachment Level, Keratinized Tissue Width, Plaque Index, Gingival Index and Sensitivity. The percentage of root coverage was 91.18 ± 21.26 at 6 months, 90.18 ± 22.04 at 12 months and 90.83 ± 18.41 at 24 months. Complete root coverage was 81% (13 out of 16) at 6 and 12 months. At 24 months, complete root coverage was 75% (9 out of 12). The plaque and gingival indexes did not vary significantly between baseline and measurement times. Probing depth was maintained at healthy levels during the months of follow-up. Sensitivity decreased at 12 months (4 of 16) compared to baseline (14 of 16), and was maintained at 2 years (2 of 12). This retrospective study showed that acellular dermal matrix allograft could be considered a useful alternative for the treatment of single gingival recessions, reducing the discomfort and morbidity associated with the palatal donor site.

Dental fluorosis severity in children 8-12 years old and associated factors

The aim of this study was to determine the frequency and severity of dental fluorosis (DF) and the association between severity and risk factors. In a cross-sectional study, 8- to 12-year-old children, born in a Colombian district, were evaluated according to the Thylstrup and Fejerskov Index (TFI) by two calibrated examiners. Molar Incisor Hypomineralization (MIH) and dental caries (DC) were also evaluated. Ordinal logistic regression was applied p<0.05). Risk factors and lifestyle factors were collected using a questionnaire answered by parents. DF was detected in 76 (98.7%) of the children (average of 18.4 ±1.81 permanent teeth affected). Grade TF2 was the most frequently observed (34.8%); TF5 was observed in all age groups; TF6- TF7 were observed in 12-year-olds. No association was found between DF severity and DC (Odds Ratio (OR)=1.35; 95%CI: 0.56-3.26) or MIH (OR=1.39; 95%CI: 0.43-4.46). DF severity was significantly associated with use of an indoor wood stove for food preparation (OR = 9.34; 95%CI: 1.11-78.57) and use of a pea-sized volume of toothpaste (OR = 27.42; 95%CI: 1.57-477.36). Prevalence of DC was 38.1% and prevalence of MIH was 14.4%. In this population, the frequency of DF was high and severity was associated with use of an indoor wood stove for food preparation and toothpaste amount used during childhood.

Prevalence of three-rooted primary mandibular first and second molars: clinical and radiographic findings in a Mexican population

The aim of this study was to determine prevalence and describe the clinical and radiographic findings of three-rooted primary mandibular first and second molars in a Mexican population. Intraoral periapical radiograph, orthopantomogram or cone beam computed tomography (CBCT) were obtained. A total 2284 children from the state of Puebla, Mexico were examined, of whom 20 presented an anatomic variant in tooth crown shape. Of the total teeth with crown alterations, 10 first and 5 second primary mandibular molars were found to have supernumerary roots. In one case, it was possible to obtain micro-CT images. The study recorded prevalence, unilateral or bilateral occurrence, and ratio between sexes. Data were analyzed using descriptive statistics. Clinical findings were presence of an anatomical variation (tuberculum paramolare / right and/or left cervical convexity) in primary mandibular first molars. Second molars presented conventional crown morphology. Prevalence of three-rooted primary mandibular first and second molars was 0.44% and 0.22%, respectively. Male: female ratio for presence of threerooted primary mandibular first molars was 4:1, showing genetic predisposition in males, and for second molars it was 1.5:1, with no predisposition according to sex. The clinical and radiographic anatomical variants in primary molars should be considered by pediatric dentists during routine care because they may cause difficulties in restorations.

Cytotoxic and anti-inflammatory effects of chitosan and hemostatic gelatin in oral cell culture

Chitosan is a biopolymer with bactericidal/bacteriostatic effect, biocompatible and biodegradable. It has been used in tissue engineering to replace tissues partially or completely by releasing bioactive materials or influencing cell growth, usually in regenerative medicine and dentistry. The aim of this study was to evaluate the cytotoxic and anti-inflammatory effect of chitosan alone or with hemostatic gelatin (Spongostand®) in cultures of human pulp cells (HPC), human gingival fibroblasts (HGF) and mouse pre-osteoblasts (MC3T3-E1, ATCC). HPC and HGF were isolated from patients. Cells were subcultured in DMEM. Chitosan was inoculated at different concentrations (0-0.5%) and hemostatic gelatins impregnated with chitosan (0.19%) were placed directly in the presence of cells and incubated for 24 hours. Cell viability was determined by MTT method and mean cytotoxic concentration (CC50) was calculated from the dose-response curve. Anti-inflammatory effect was calculated from the in vitro gingivitis model induced with interleukin 1beta (IL-1β) in HGF and protein detection. The data were subjected to Shapiro-Wilk, Kruskal-Wallis and Mann-Whitney tests. Experiments were performed in triplicate of three independent assays. Cell viability of HPC, HGF and MC3T3-E1 in contact with chitosan decreased significantly (p<0.05). The HPC were the most sensitive (CC50= 0.18%), followed by HGF (CC50=0.18%) and MC3T3-E1 (CC50= 0.19%). The cytotoxicity of gelatins impregnated with chitosan decreased cell viability of HGF and HPC by 11% and 5%, respectively. The proinflammatory effect was reduced significantly in the gingivitis model. To conclude, chitosan induces moderate cytotoxic effects alone or with hemostatic gelatin at 0.19%, in dose-dependent manner, with anti-inflammatory effects on human gingival fibroblasts. The use of chitosan as a biomaterial can be an excellent choice for use in regenerative dentistry.

Efficacy of different instruments for the mechanical removal of the smear layer in immediate post preparations: a comparative study

Adhesively cemented fiber-reinforced composite posts are commonly used to reconstruct endodontically treated teeth. Adhesion to intraradicular dentin is complex, and close contact between the resin cements and the dentin is essential. The removal of the smear layer following post space preparation (secondary smear layer) can improve this integration. Different mechanical systems have been used to activate the irrigant inside the root canal. The purpose of this study was to compare, ex-vivo, the removal of the smear layer from the walls of the immediate post space preparation by the action of three mechanized instruments. Forty premolar specimens with a single root canal were selected, endodontically treated, and shaped for glass fiber post cementation with Peeso reamer #1 (Dentsply Sirona, Switzerland) and Macrolock finishing drill #3 (RTD, France). The specimens were randomly divided into 4 groups (n=10): Group C (control); Group PUI (passive ultrasonic irrigation); Group CEP (Rotoprox brush, Hager Werken, Germany) and Group XP (XP-endo Finisher, FKG Dentaire, Switzerland). Post space surfaces were cleaned with 3mL of distilled water; each specimen root split longitudinally to expose the root canals, and prepared for examination in a scanning electron microscope at magnification 350X. The results were analyzed using the Kruskal-Wallis and Friedman tests (p>0.05). RESULTS: Statistically significant differences (p <0.05) were found between Groups C and XP in all three root regions, but not between Groups C, CEP and PIU. Of these, Group CEP showed a better trend in the results of the coronary and middle thirds, without significant difference with Group XP. Although it was difficult to achieve a clean dentin surface after preparation for the fiberglass post, the XP-endo Finisher was the most efficient in removing secondary smear layer, followed by the Rotoprox conical brush.

Prevalence and Distribution of Molar Incisor Hypomineralization in children receiving dental care in Caracas Metropolitan Area, Venezuela

Great variation has been reported in worldwide prevalence of Molar Incisor Hypomineralization (MIH) and Hypomineralized Second Primary Molar (HSPM). South America has the highest regional prevalence. The aim of this study was to determine the prevalence and distribution of MIH HSPM in 6- to 12-year-old children who received care at two dental healthcare services (public and private) in Caracas Metropolitan Area, Venezuela. A cross-sectional prospective study was conducted on 145 children, of whom 121 were selected in the stratified random sample. A calibrated examiner (Kappa=0.878/0.831) evaluated all patients following the MIH diagnosis criteria established by the European Academy of Paediatric Dentistry and using a valid and reliable instrument. Data were analyzed with a significance level of 5%. Of the 121 children, 46.28% (56) were male and 53.72% (65) female, average age 8.83 ± 1.61. The prevalence of MIH/HSPM was 25.6%/20%. Both enamel defects were more prevalent in females (p-value=0.026/0.005). Severe MIH/HSPM was present in 21.8%/31.2% of cases. Average number of affected teeth was 4.16 ± 2.19/1.68 ± 0.74; and the condition was more frequent in upper molars (67.7%/51.4%). It was concluded that prevalence of MIH in 6- to 12-year-old Venezuelan children who received care in Caracas Metropolitan Area was higher than the previously estimated prevalence for South America, with predominance of mild affectation and more frequently occurring in upper molars.

Impact of soft tissue graft on the preservation of compromised sockets: a randomized controlled clinical pilot study

The aim of this pilot study was to evaluate the impact of the association of free gingival graft (FGG) or collagen-matrix xenograft (CMX) to deproteinized bovine bone graft (DBBG) on the preservation of post-extraction sockets with facial-wall defects. Sixteen patients who presented a maxillary tooth with a facial bone defect and indication of extraction were selected. After the surgical procedure, all the post-extraction sockets were filled with DBBG and covered with a collagen membrane. The cervical part of the socket was then sealed with either FGG or CMX. Clinical and tomographic analyses were performed at baseline and 4 months after the grafting procedure. The FGG sockets showed higher values for the width of the bone ridge than the CMX sockets at 4 months. There was no difference regarding biopsy composition. In conclusion, regardless of the type of soft tissue graft used, socket preservation with DBBG at sites presenting facial bone defects enabled implant placement without further guided bone regeneration, whether the sockets were sealed with FGG or CMX.