Mechanical Properties and Ion Release from Fibre-Reinforced Glass Ionomer Cement.

The aim of this study was to compare the mechanical properties and ion release from a commercially available resin-modified glass ionomer cement to a formulation reinforced by the addition of short glass fibres at various percentages. Methods: Three experimental groups were prepared by adding a mass ratio of 10%, 15% and 20% of short glass fibres to the powder portion of the cement from a capsule (GC Fuji II LC), while the control group contained no fibres. Microhardness (n = 12), fracture toughness, and flexural, compressive and diametral tensile strength (n = 8) were evaluated. To study ion release, readings were obtained utilising fluoro-selective and calcium-selective electrodes after 24 h, 7 days and 30 days (n = 12). The spatial distribution of fibres within the material was evaluated through scanning electron microscopy. The data were analysed using one-way ANOVA with a Bonferroni adjustment. Results: The findings suggest that elevating fibre weight ratios to 20 wt% results in improved mechanical properties (p < 0.05) in microhardness, flexural strength, diametral tensile strength and fracture toughness. In terms of ion release, a statistically significant difference (p < 0.001) was observed between the groups at the conclusion of 24 h and 7 days, when the fluoride release was much higher in the control group. However, after 30 days, no significant distinction among the groups was identified (p > 0.05). Regarding calcium release, no statistically significant differences were observed among the groups at any of the evaluated time points (p > 0.05). SEM showed the fibres were homogeneously incorporated into the cement in all experimental groups. Conclusions: Resin-modified glass ionomer enhanced with short glass fibres at a weight loading of 20% showcased the most favourable mechanical properties while concurrently maintaining the ability to release fluoride and calcium after a 30-day period.

Short-Term Fluoride Release from Ion- Releasing Dental Materials.

Objective: To compare short-term release of fluoride ions from ion-releasing dental restorative materials. Material and methods: Seven experimental groups were prepared using the following six different materials: alkasite (Cention Forte), resin-modified glass ionomer cement (Fuji II LC), bioactive composite (ACTIVA BioACTIVE-RESTORATIVE), fluoride-containing nano-hybrid composite (Luminos UN), coat-free glass hybrid (EQUIA Forte HT), coat-applied glass hybrid (EQUIA Forte HT), and glass ionomer cement (Fuji IX). A total of 40 samples for each group (n=40) were prepared in Teflon molds (8 mm x 2 mm) and placed in polyethylene vials with 5 ml of deionized water. Fluoride release was measured after 6, 24, 48 hours, and for 5 weeks using an ion-selective electrode. The results were expressed in mg/l and the data were statistically analyzed using ANOVA. Results: Significant differences in fluoride release were observed within the first 6 hours (ANOVA p<0.001). EQUIA Forte HT had the highest release, while the other materials showed no significant differences. After 24 hours, EQUIA Forte HT (p<0.001) and Luminos UN (p<0.05) exhibited significantly higher releases, compared to other tested materials. EQUIA Forte HT maintained the highest release at 48 hours (p<0.001), followed by Cention Forte (p<0.05) and Luminos UN (p<0.05). All material pairs showed significant differences in fluoride release at 5 weeks (p<0.001). Conclusion: Coat-free EQUIA Forte HT had the overall highest fluoride release, while Cention Forte demonstrated the greatest increase over time. ACTIVA BioACTIVE-RESTORATIVE exhibited the lowest fluoride release in this study.

Attitude and practice of regenerative endodontic procedures among endodontists and paediatric dentists: A multinational survey from 13 countries.

BACKGROUND: Regenerative endodontics (RET) refers to biologically based procedures that aim to restore damaged tooth structures and reinstate the pulp-dentine complex to its normal physiological state. AIM: The purpose of this study was to examine the attitudes and practices of endodontists and paediatric dentists regarding RET. DESIGN: A survey was conducted among endodontists and paediatric dentists from 13 countries. A number of factors were evaluated, including frequency of RET application, followed guidelines, disinfection techniques, intracanal medication type, scaffold type, preferred coronal seal material, and follow-up period. RESULTS: Among the 1394 respondents, 853 (61.2%) and 541 (38.8%) were endodontists and paediatric dentists, respectively. Almost half (43%) of participants have not performed RET yet. The American Association of Endodontics guideline (47.3%) was selected as the primary source for the clinical protocol. The most frequently selected irrigant solution was 1.5%-3% NaOCl at the first (26.1%) and second (13.6%) sessions. A blood clot (68.7%) and MTA (61.9%) were the most frequently selected scaffold type and coronal barrier. Most participants preferred a 6-month follow-up period. CONCLUSION: According to this survey, deviations exist from current RET guidelines regarding all aspects evaluated. Standardizing clinical protocols and adhering to available guidelines would help to ensure more predictable outcomes.

Efficacy of Shock Wave-Enhanced Emission Photoacoustic Streaming (SWEEPS) in the Removal of Different Combinations of Sealers Used with Two Obturation Techniques: A Micro-CT Study.

This study sought to evaluate the efficacy of SWEEPS in the removal of epoxy-resin-based and calcium-silicate-containing endodontic sealer combined with single-cone and carrier-based obturation techniques through a micro-CT analysis. Seventy-six single-rooted extracted human teeth with single root canal were instrumented with Reciproc instruments. Specimens were randomly divided into four groups (n = 19) according to the root canal filling material and obturation technique: (1) AH Plus sealer + Reciproc gutta-percha, (2) TotalFill BC sealer + TotalFill BC Points, (3) AH Plus sealer + Guttafusion obturator, and (4) MTA Fillapex + Guttafusion obturator. All specimens were re-treated one week later using Reciproc instruments. Following re-treatment, root canals were additionally irrigated using the Auto SWEEPS modality. The differences in the root canal filling remnants were analyzed by micro-CT scanning of each tooth after root canal obturation, after re-treatment, and after additional SWEEPS treatment. Statistical analysis was performed using an analysis of variance (p < 0.05). The additional treatment with SWEEPS significantly reduced the volume of the root canal filling materials in all experimental groups compared to the removal of root canal filling using only reciprocating instruments (p < 0.05). However, the root canal filling was not removed completely from any of the samples. SWEEPS can be used to enhance the removal of both epoxy-resin-based and calcium-silicate-containing sealers, in combination with single-cone and carrier-based obturation techniques.

Effect of Conventional Adhesive Application or Co-Curing Technique on Dentin Bond Strength.

The aim of this in vitro study was to assess the effect of two different adhesive application methods on shear dentin bond strength (ISO 29022) using three various adhesive systems. A mid-coronal section of 77 intact third human molars with fully developed apices was made to create flat bonding substrates. The materials used in the study were Excite F (Ivoclar Vivadent), Prime&Bond Universal (Dentsply Sirona) and G-Premio Bond (GC). The application of each adhesion system was performed in two different ways. In the first group, the bonding agent was light cured immediately after the application (conventional method), while in the second group the adhesive and composite were cured concurrently ("co-curing" method). A total of 180 specimens were prepared (3 adhesives × 2 method of application × 30 specimens per experimental group), stored at 37 °C in distilled water and fractured in shear mode after 1 week. Statistical analysis was performed using ANOVA and Weibull statistics. The highest bond strength was obtained for Prime&Bond conventional (21.7 MPa), whilst the lowest bond strength was observed when co-curing was used (particularly, Excite F 12.2 MPa). The results showed a significant difference between conventional and co-curing methods in all materials. According to reliability analysis, the co-curing method diminished bond reliability. Different application techniques exhibit different bond strengths to dentin.

Assessment of Damage of Endodontic Instruments with Naked Eye and Optical Instruments.

OBJECTIVES: To determine the accuracy of visual damage evaluation of rotating and reciprocal endodontic instruments with the naked eye and optical devices. MATERIAL AND METHODS: Four examiners were involved, divided into two age groups: I. 20-30 years, n = 2, II. 40-50 years, n = 2. They visually assessed the existence of damage to rotating or reciprocal endodontic instruments by their naked eye and with two types of optical aids. A total of 239 instruments from different manufacturers were evaluated by each examiner. Before damage estimation, each examiner calibrated the eye on a new instrument. Sensitivity of the detection method was calculated as by the naked eye. When an instrument was detected as damaged by the naked eye, the damage assessment was stopped and the instrument was considered to be damaged by the other two methods, as well. RESULTS: Damage was found in 178 instruments. Sensitivity of the naked eye was calculated to be 49.7%, for the loupe 66.2% and for the operating microscope 76.5%. The three methods of damage assessment had significant differences (p < 0.05) in sensitivity. CONCLUSION: It was concluded that there is a significant difference between age groups in estimating instrument damage. Also, it was noted that the damage assessment with the naked eye and optical aids were different. Finally, in terms of ease of damage recognition, significant differences between the types of engine-driven endodontic instruments were found. However, no type of instrument was more prone to damage than any other type of instrument.

Effect of Nano-Filled Protective Coating and Different pH Enviroment on Wear Resistance of New Glass Hybrid Restorative Material.

The purpose of the study was to determine the wear rate of Equia Forte HT Fil with Equia Forte Coat or without coating and compare it with Fuji IX GP high-viscosity glass ionomer cement (GIC) in conditions with acid load or at neutral pH. The samples were stored for 7 days: (1) in artificial saliva, (2) in artificial saliva and cyclically exposed to low pH, and (3) in distilled water and cyclically exposed to low pH. Wear was determined by measuring the difference in mass before and after brushing in an abrasion testing device. The wear of Fuji IX GP was significantly higher than that of Equia Forte HT Fil with or without coating (p = 0.000). The difference between Equia Forte HT Fil with and without Coat was not statistically significant (p < 0.803). The differences in wear resistance between samples stored in saliva and in distilled water were not significant (p = 0.588). Periodic exposure to the low pH solution significantly affected the wear resistance of all materials (p = 0.000). Equia Forte HT Fil was more resistant to wear than Fuji IX GP in all storage conditions. A resinous coat did not significantly increase wear resistance.

Impact of oral hygiene instructions on plaque index in adolescents.

OBJECTIVE: The objective of the study, which consisted of a motivational lecture and hands-on training, was to evaluate the role of oral hygiene education for adolescents. METHODS: The study population included sixty-two high school students between fourteen and fifteen years of age (thirty males and thirty-two females). The response rate was 76.5%. The measurement of oral hygiene level was performed using the modified Green Vermilion Index (GVI). The values were recorded at baseline, one week, three months, and six months after education through motivational lecture and hands-on training was performed. Descriptive and nonparametric statistical methods were used in statistical analysis. Level of significance was 0.05. RESULTS: At the beginning of the study, the GVI of all examined subjects was 3.52 (SD = 0.70). One week after the motivational lecture and training, it decreased to 2.64 (SD = 0.69). Three months later, the level of plaque index had the lowest value (1.44; SD = 0.66). At the end of the study the level of plaque index increased to 2.52 (SD = 0.86). CONCLUSIONS: A significant oral hygiene improvement in adolescents as a result of education was presented. However, due to a decline in oral hygiene level six months after the education, there is a need for educational programmes continuity.

Incidence of Dentinal Microcracks during Root Canal Preparation with Self Adjusting File, Reciproc Blue and ProTaper Next.

Introduction: Forces formed during root canal instrumentation could cause the crack formation in dentinal walls. Their propagation may result in vertical root fracture and eventually tooth loss. The aim of the study was to explore microcrack formation after root canal preparation with Self-adjusting File (SAF), Reciproc Blue (RB), and ProTaper Next (PTN) instruments on young premolars by means of micro-computed tomography (micro CT). Methods and Materials: Forty-five upper premolars with two canals, were extracted due to orthodontic reasons from patients aged 16 to 20 years and stored for up to two months. The teeth were scanned with a micro-CT (Nikon XT H 225, Tring, UK) at structural resolution of 20.2 µm and randomly divided into three groups: SAF, RB, and PTN. Specimens were instrumented and irrigation was performed with 12 mL of 2.5% sodium hypochlorite (NaOCl) and 4 mL of 17% ethylenediaminetetraacetic acid (EDTA) per root canal. Subsequently, the specimens were scanned under the same conditions as before, in wet condition and 24 h after drying. The presence of microcracks in dentinal walls was evaluated using the image-processing software Volume Graphics VGStudio Max 3. Results: No dentinal defect was found in any evaluated specimen, neither in pre-nor post-operative scans in wet and dry condition. Conclusion: Under the circumstances of this in vitro study instruments with improved design and metallurgy do not cause dentinal microcracks in young premolar teeth.

Clinical and Radiographic Assessment of Cases Referred to Endodontic Surgery.

OBJECTIVE: The objective of the study was to assess the quality of root canal fillings of cases referred to endodontic surgery using preoperative radiographs and correlate it with endodontic surgery treatment decision. The objective was also to analyse clinical symptoms and size of periapical lesions on radiographs and correlate them with treatment decisions including non-surgical retreatment, endodontic surgery and extraction. MATERIALS AND METHODS: A questionnaire was composed to record the data. Eighty-six patients with 109 teeth, who were referred to endodontic surgery, participated in the research. The quality of root canal filling was assessed according to its homogeneity and filling length on digital radiographs. The data were analyzed using χ2-test and t-test. RESULTS: Of the teeth referred to endodontic surgery, 97.2% were treated by a general practice dentist, endodontic retreatment was attempted in 20.6%, and root canal filling was homogeneous and within 1 mm from the apex in 21.6%. Endodontic surgery, retreatment, extraction and no treatment were selected in 90.1%, 5.4%, 1.8% and 2.7% of the cases, respectively. CONCLUSIONS: Low percentage of adequate root canal fillings and high percentage of endodontic surgery decisions suggest that there is a need to increase awareness of non-surgical retreatment options.

Self Assessment of Dental students' Perception of Learning Environment in Croatia, India and Nepal.

AIM: The aim of this study was to assess dental students' perception of different learning environment in India, Nepal and Croatia. METHODS: The study was conducted during a period of academic year 2016/17. A total of 849 dental students participated in the study. There were 188 respondents from Croatia, 373 from India, and 288 from Nepal. Non-responders were not followed up. The Dental Student Learning Environment Survey (DSLES) was used which consisted of 55 items subdivided into seven scales. The scales measured the following perceptions: Flexibility, 'Student-to-Student Interactions, Emotional Climate, Supportiveness, Meaningful Experience, Organization and Breadth of Interest. Statistical analysis of the data utilised the Kolmogorov Smirnov test. The Kruskal-Wallis "non-parametric ANOVA" was also used to test the differences between the countries. A post hoc analysis was performed using Ranks tables and the Median test. RESULTS: The response rate was 26.9%. Significant differences between the countries were found for all DSLES variables (Kruskal-Wallis, p<0.01). The Median test also showed significant differences between the countries for all DSLES variables (p<0.01). The scales with the highest mean values were 'Student-to-student interactions' in India and Nepal, and the 'Emotional Climate' in Croatia. CONCLUSIONS: Students in Croatia rated their school only with grades excellent and good, while their colleagues in India and Nepal were more critical. Despite the different settings in three countries, 'Flexibility' was identified as the area of weakness in all three educational systems.

Proteomics profiling of keratocystic odontogenic tumours reveals AIDA as novel biomarker candidate.

BACKGROUND: Keratocystic odontogenic tumour (KCOT) is a benign, yet aggressive odontogenic tumour. Herein, proteome analysis of KCOT lesions in comparison with control patient-matched tissue unaffected by the disease and with inflammatory odontogenic cysts, namely radicular cysts is presented. METHODS: For the proteomics profiling, two complementary proteomics techniques MALDI-MS/MS and LC-ESI-MS/MS were employed. Potential candidate biomarkers were validated by immunohistochemistry. RESULTS: More than 43 proteins were found to be differentially expressed or up-regulated in KCOT lesions in comparison with patient-matched unaffected oral mucosa. These proteins bear important biological functions and are involved in cell proliferation, cytoskeletal re-organization, transcription, cellular motility and apoptosis. In particular, a number of differentially expressed proteins participate in autocrine regulation and signalization within JNK and p38 MAPK signalling pathways. CONCLUSIONS: Immunohistochemical validation of chosen putative biomarkers revealed axin interaction partner and dorsalization-antagonist (AIDA), known as a protein that blocks activation of JNK signalling pathway, as a differential biomarker for KCOT lesions on an independent cohort of KCOT tissue samples in comparison with most prevalent intra-oseal lesions inflammatory odontogenic cysts.

Prevalence of apical periodontitis and quality of root canal fillings in population of Zagreb, Croatia: a cross-sectional study.

AIM: To determine the prevalence of apical periodontitis and assess the quality of endodontic fillings in the population of the city of Zagreb, Croatia. METHODS: A total of 1462 orthopantomograms from new patients at 6 different dental practices was analyzed during 2006 and 2007. The presence of periapical lesions was determined by using the periapical index score (PAI). The quality of endodontic fillings was assessed according to the filling length and homogenicity. Data were analyzed using t test and ANOVA with Scheffe post-hoc test. RESULTS: There were 75.9% of participants with endodontically treated teeth and 8.5% of all teeth were endodontically treated. Only 34.2% of endodontically treated roots had adequate root canal filling length, while 36.2% of root canal fillings had homogenous appearance. From the total number of teeth with intracanal post, 17.5% had no visible root canal filling. Using PAI 3 as a threshold value for apical periodontitis, periapical lesions were detected in 8.5% of teeth. Adequate quality of root canal fillings was associated with a lower prevalence of periapical lesions. CONCLUSION: We found a large proportion of endodontically treated teeth with apical periodontitis and a correlation between the quality of endodontic filling and the prevalence of periapical lesions. This all suggests that it is necessary to improve the quality of endodontic treatment in order to reduce the incidence and prevalence of apical periodontitis.