Initial bacterial adherence and biofilm formation on novel restorative materials used in paediatric dentistry.

OBJECTIVE: To evaluate the initial bacterial adherence and biofilm formation on novel restorative materials in paediatric dentistry and compare the results to stainless steel crown and primary enamel. MATERIALS AND METHODS: Twenty-five samples (Diameter = 4 mm) from five restorative materials (Tetric Power Fill light cured for 3 s or 10 s, Fuji II LC, Equia Forte HT Fil, Cention Forte, Stainless-steel crown) and primary enamel were prepared. Four samples served for recording of surface roughness (Ra) using a contact profilometer, 21 samples were incubated in stimulated human saliva for 2 h (initial bacterial adherence) and 72 h (biofilm formation) and served to determine ion releasing and bacterial growth. After 2 and 72 h, the number of colony-forming units (CFU) per ml was counted and expressed in Log10 CFU/ml. Data were analysed with two-way ANOVA and Tuckey's multiple comparisons test (p < 0.05). RESULTS: All tested materials showed similar initial bacterial adherence (p > 0.1). Stainless steel crown showed statistically significantly less biofilm formation than all other tested materials (p ≤ 0.02), except for Fuji II LC (p = 0.06). In terms of biofilm formation, the differences between all tested materials were not statistically significant (p ≥ 0.9). SIGNIFICANCE: Novel restorative materials in paediatric dentistry show similar initial bacterial adherence and biofilm formation. However, compared to other restorative materials, stainless steel crowns demonstrate the lowest level of biofilm formation. Ion-releasing materials may not necessarily show better antimicrobial properties than conventional materials.

Is there a rise of prevalence for Molar Incisor Hypomineralization? A meta-analysis of published data.

Since Molar Incisor Hypomineralization was first described as a pathologic entity, public perception often suggests a considerable rise in prevalence of the respective disease. Since there are still considerable doubts regarding the etiology and-accordingly-prevention of MIH and respective therapeutic approaches are difficult this question is of considerable clinical and public interest. Accordingly, a systematic literature search in accordance with the PRISMA guidelines for systematic reviews on Medline, Cochrane Database, EMBASE, LILACS, Web of Science, Google scholar, Scopus was performed to retrieve original articles reporting the prevalence of MIH as defined by the European Academy of Pediatric Dentistry (EAPD). From initially 2360 retrieved titles, 344 full texts were assessed for possible inclusion and finally 167 articles of mainly moderate to high quality and based on data of 46'613 individuals were included in the meta-analysis. All studies published before 2001 had to be excluded since it was not possible to align the findings with the EAPD classification. Studies varied considerably regarding cohort size (25 to 23'320, mean 1'235)) and age (5.6-19 y, mean 9.8 y). Over all studies, the weighted mean for the prevalence for MIH was 12.8% (95% CI 11.5%-14.1%) and no significant changes with respect to either publication year or birthyear were found. A sub-analysis of eleven studies reporting on the prevalence in different age groups, however, revealed strong evidence for an increasing prevalence between the years 1992 (3%) and 2013 (13%).Therefore, based on data from cross-sectional studies a possible rise in prevalence of MIH remains unclear. Future prospective large-scale studies under standardized examination conditions with an emphasis on examiner calibration are needed to gain better understanding in the evolution of the prevalence of MIH.

Masking capacity of minimally invasive lithium disilicate restorations on discolored teeth-The impact of ceramic thickness, the material's translucency, and the cement color.

OBJECTIVES: To evaluate minimally invasive restorations' capacity to mask discolored teeth and explore the impact of ceramic thickness, translucency, and cement color. MATERIALS AND METHODS: Twenty-four assessment pairs of naturally colored and discolored bovine dentin samples were formed, using lithium disilicate specimens in six different thicknesses (0.3-0.8 mm), two different translucencies (high, low), and two cements (transparent, tooth-colored). Evaluators assessed the color differences in each assessment pair, and the threshold for detecting a color difference was determined using sequential testing and the Bonferroni-Holm method. RESULTS: A thickness of 0.6 mm effectively masked color differences using high translucent ceramic with transparent cement, detectable differences were still observed at 0.7/0.8 mm. A threshold thickness of 0.4 mm was seen using high translucent ceramic and tooth-colored cement, with color differences still discernible at 0.5 and 0.8 mm. A threshold thickness of 0.4 mm was detected using low translucent ceramic and transparent cement, while detectable differences persisted at 0.5, 0.7, and 0.8 mm. A 0.5 mm threshold thickness was observed when using low translucent ceramic and tooth-colored cement, and no detectable color differences were detected beyond this thickness. CONCLUSIONS: Masking can be achieved with a thickness of 0.4-0.5 mm using a low translucent material and tooth-colored cement. CLINICAL SIGNIFICANCE: Understanding the impact of ceramic thickness, translucency, and cement color can aid clinicians in making informed decisions for achieving the best esthetic outcomes while preserving tooth structure. Effective masking can be accomplished with ceramic thicknesses starting at 0.4 mm, especially when employing a low translucent material and tooth-colored cement. However, clinicians should be aware that discolorations may still be detectable in certain scenarios when using minimally invasive lithium disilicate restorations.

Supplementation of Energy Drinks with Green Tea Extract: Effect on In Vitro Abrasive/Erosive Dentin Wear.

PURPOSE: To investigate the effect of the supplementation of energy drinks with green tea extract on abrasive and erosive dentin wear. MATERIALS AND METHODS: Six groups, each comprising 15 bovine dentin samples, were prepared, yielding a total of 90 samples. Erosion was performed by immersing the samples in Red Bull and Red Bull light with and without green tea extract. Tap water with and without green tea extract was used as the control groups. The samples were subjected to abrasive/erosive cycling for five days. The following cycling was performed daily: toothbrush abrasion (20 brushstrokes; 2.5 N); eight erosive cycles (2 min storage in the respective solutions); in between the erosive cycles, storage in artificial saliva (60 min) and again toothbrush abrasion (20 brushstrokes; 2.5 N). During the night, samples were again stored in artificial saliva. Abrasive/erosive dentin wear was measured using a stylus profilometer (µm, accuracy = 40 nm). The measured dentin loss results from the vertical position shift on the y-axis from base to final profile after the wear process in 2D. Pairwise comparisons between the groups were carried out using Wilcoxon signed-rank test. RESULTS: The following dentin wear (median [IQR]) was measured: Red Bull: 1.9 µm (0.5); Red Bull Light: 1.3 µm (0.3); Red Bull with green tea extract: 0.8 µm (0.3); Red Bull Light with green tea extract: 0.3 µm (0.5); Tap water with green tea extract: -0.2 µm (0.7); Tap water: -1.0 µm (1.2). The comparison of all tested groups to each other proved to be statistically significant (p < 0.05). CONCLUSION: The supplementation of energy drinks with green tea extract provide a protective effect against erosive/abrasive wear in vitro.

A laboratory pilot study on voids in flowable bulk-fill composite restorations in bovine Class-II and endodontic access cavities after sonic vibration.

This pilot study investigated whether sonic-powered application of a bulk-fill resin-based composite (RBC) in Class-II or endodontic access cavities reduces void formation. The crowns and roots of 60 bovine teeth with Class-II cavities (C) and endodontic access cavities (E) respectively, were assigned to ten groups (C1-C5, E1-E5). Cavities were filled with RBC (SDR flow + , one increment) using different application techniques: no adaptation (C1 + E1), spreading of RBC on the cavity surfaces with a dental explorer tip (C2 + E2), low (C3 + E3) or high frequency (C4 + E4) direct activation by inserting a sonic-powered tip into RBC and high frequency indirect activation with an ultrasonic insertion tip (C5 + E5). The restorations were light-cured and investigated for voids using microtomography. The number of voids and percentage of voids related to the volume were statistically analysed (α < 0.05). While most voids in Class-II restorations were observed in C4 (p ≤ 0.0031), no significant differences were found between the other groups (p > 0.05). The percentage of voids showed no differences in E1-E5 (p > 0.05). C4 showed a significantly higher percentage of voids compared to C2 (p < 0.001). There is no benefit in applying sonic vibration when filling Class-II or endodontic access cavities.

Dynamic interactions between Candida albicans and different streptococcal species in a multispecies oral biofilm.

The oral cavity is colonized by a plethora of bacteria, fungi, and archaea, including streptococci of the mitis group (MSG) and the yeast Candida albicans. This study aims to investigate the role of streptococcal species in the development of oral biofilm and the cross-kingdom interactions between some of the members of the commensal MSG and the pathogen yeast C. albicans using a multispecies supragingival biofilm model. A total of nine different in vitro biofilms were grown, quantified with culture analyses, and visually examined with confocal laser scanning microscopy (CLSM). A four-species biofilm without any streptococcal species was used as a basic biofilm. In each subsequent inoculum, one species of MSG was added and afterward combined with Streptococcus mutans. The eight-species biofilm contained all eight strains used in this study. Culture analyses showed that the presence of S. mutans in a four-species biofilm with Streptococcus oralis or S. oralis subsp. tigurinus did not differ significantly in C. albicans colony-forming unit (CFU) counts compared to biofilms without S. mutans. However, compared to other mitis species, Streptococcus gordonii combined with S. mutans resulted in the lowest CFUs of C. albicans. Visual observation by CLSM showed that biofilms containing both S. mutans and one species of MSG seemed to induce the formation of filamentous form of C. albicans. However, when several species of MSG were combined with S. mutans, C. albicans was again found in its yeast form.

Description of a new laboratory evaluation method of interdental brush abrasion as a clinical hazard.

OBJECTIVES: To simulate the abrasive potential of an interdental brush when applied with toothpastes and prophylactic gels/solutions in a novel laboratory brushing simulation set-up. METHODS: A brushing device was customized to treat dentin samples mimicking a simplified interdental space with an interdental brush (ISO 2). The brushing, that is, 7200 strokes for 1 h, was performed with artificial saliva (control), a povidone-iodine solution, and slurries of chlorhexidine and fluoride gels as well as three toothpastes with different RDA values ranging from 29 to 100, respectively. The loss of dentin was profilometrically assessed and compared with ANOVA and Fishers LSD. RESULTS: While artificial saliva as control, the solution and the gel slurries showed no measurable dentin loss, toothpastes resulted in a measurable linear surface damage with respect to the actual intrinsic RDA values and ranged from 12.6 to 26.5 µm (p < 0.001). CONCLUSIONS: Any interdental cleaning product should be tailored and carefully instructed. Any over- and misuse should be avoided, which applies especially to the use of interdental brushes in combination with abrasive toothpastes.

Influence of high-irradiance light curing on the marginal integrity of composite restorations in primary teeth.

BACKGROUND: Reducing the necessary time to restore primary teeth improves the cooperation of paediatric patients. This study aimed to investigate the marginal integrity of restorations prepared with a bulk-fill resin-based composite (RBC) containing additional fragmentation chain transfer (AFCT) compared to a conventional RBC when light cured with a rapid high-irradiance (3 s) and a regular (10 s) curing mode. METHODS: Forty class-II cavities were prepared in 40 primary molars. The molars were randomly divided into four groups based on the applied light-curing modes (regular: 10 s @ 1200 mW/cm2 or high-irradiance: 3 s @ 3000 mW/cm2) and the used restorative material (AFCT-containing bulk-fill RBC "Power Fill" or AFCT-free conventional RBC "Prime"). After thermo-mechanical loading, the marginal integrity was analysed using scanning electron microscopy. A beta regression model and pairwise comparisons were used to statistically analyse the data. RESULTS: The mean marginal integrity (% ± SD) of the restorations for each group was as follows: Power Fill (10 s: 79.7 ± 15.6) (3 s: 77.6 ± 11.3), Prime (10 s: 69.7 ± 11.1) (3 s: 75.0 ± 9.7). The difference between the RBCs for the same light-curing mode was statistically significant (p ≤ 0.05). The difference between the light-curing modes for the same RBC was not statistically significant (p ˃ 0.5). CONCLUSIONS: AFCT-containing bulk-fill RBC "Power Fill" achieves similar marginal integrity when light-cured with either high-irradiance or regular light-curing modes. "Power Fill" achieves better marginal integrity than the conventional RBC "Prime" regardless of the applied light-curing mode.

Varnish with S-PRG filler reduces dentin permeability after erosive/abrasive challenge.

PURPOSE: To evaluate the effect of different varnishes on dentin permeability to erosive/abrasive challenges. METHODS: 60 superficial dentin discs were randomly allocated to six groups (n=10): Duraphat, PRG Barrier Coat, Clinpro XT, Profluorid, Fluor Protector S and untreated (control). Permeability tests were carried out: after acid conditioning, after treatment, and after abrasive/erosive challenges. The abrasive-erosive challenges were performed for 5 days (citric acid and in remineralizing saliva), as well as abrasion with toothpaste slurry (Colgate Total 12). Scanning electron microscopy (SEM) images were obtained of the dentin surfaces (5,000x) after the treatments, and after the erosive/abrasive challenges. RESULTS: Kruskal-Wallis and Dunn tests showed that all the varnishes promoted a decrease in dentin permeability directly after application, with Clinpro XT showing the highest percentage (69.52%) of dentin sealing (P= 0.0188). After the erosive/abrasive challenge, only PRG Barrier Coat varnish showed dentin sealing ability with reduced dentin permeability (42.16%) (P= 0.0014). However, none of the applied varnishes promoted a statistically significant difference in the percentage of dentin sealing, compared with the control group (P> 0.05). Clinpro XT showed a higher percentage of dentin sealing, while only PRG Barrier Coat showed reduced dentin permeability after the erosive/abrasive challenge. CLINICAL SIGNIFICANCE: Varnish containing S-PRG filler has the efficacy needed to be used as a coating material to reduce dentin permeability in situations of erosive/abrasive challenges.

Water-Induced Changes in Experimental Resin Composites Functionalized with Conventional (45S5) and Customized Bioactive Glass.

The aim of the study was to evaluate microhardness, mass changes during 1-year water immersion, water sorption/solubility, and calcium phosphate precipitation of experimental composites functionalized with 5-40 wt% of two types of bioactive glass (BG): 45S5 or a customized low-sodium fluoride-containing formulation. Vickers microhardness was evaluated after simulated aging (water storage and thermocycling), water sorption and solubility were tested according to ISO 4049, and calcium phosphate precipitation was studied by scanning electron microscopy, energy dispersive X-ray spectroscopy, and Fourier-transform infrared spectroscopy. For the composites containing BG 45S5, a significant reduction in microhardness was observed with increasing BG amount. In contrast, 5 wt% of the customized BG resulted in statistically similar microhardness to the control material, while higher BG amounts (20 and 40 wt%) resulted in a significant improvement in microhardness. Water sorption was more pronounced for composites containing BG 45S5, increasing 7-fold compared to the control material, while the corresponding increase for the customized BG was only 2-fold. Solubility increased with higher amounts of BG, with an abrupt increase at 20 and 40 wt% of BG 45S5. Calcium phosphate was precipitated by all composites with BG amounts of 10 wt% or more. The improved properties of the composites functionalized with the customized BG indicate better mechanical, chemical, and dimensional stability without compromising the potential for calcium phosphate precipitation.

Marginal Integrity of Simplified Adhesive Strategies in Primary Teeth.

OBJECTIVE: The aim of this research was to investigate the effect of simplified adhesive strategies (self-etch vs selective enamel etch and 10- vs 20-second adhesive application time) on the marginal integrity in primary molars. METHODS: Forty deep class-II cavities were prepared in 40 extracted primary molars. The molars were divided into 4 groups based on the applied universal adhesive strategy as follows: groups 1 and 2: selective enamel etch with 20- or 10-second application time and groups 3 and 4: self-etch with 20- or 10-second application time. All cavities were restored with a sculptable bulk-fill composite restoration. The restorations underwent a thermomechanical loading (TML, 5-50 °C, 2-minute dwelling time, ×1000; 400,000 loading cycles, 1.7 Hz, 49 N). Marginal analysis before and after TML was conducted with scanning electron microscopy and the marginal integrity of each restoration was calculated as a percentage of continuous margins. A beta regression model was adopted to statistically analyse the data with a consequent pairwise comparison. RESULTS: The mean marginal integrity (% ± SD) of the restorations for each tested adhesive strategy after TML was as follows: selective enamel etch/20 seconds = 85.4 ± 3.9, self-etch/20 seconds = 85.3 ± 5.2, self-etch/10 seconds = 80.1 ± 8.2, and selective enamel etch/10 seconds = 80.0 ± 8.5. The difference between both adhesive strategies was not statistically significant at the same application time. The difference between both application times within the same adhesive strategy was statistically significant (P ≤ .01). CONCLUSIONS: Universal adhesives applied either in selective enamel etch or in self-etch mode result in comparable marginal integrities when restoring class-II cavities in primary molars. Shortened adhesive application time (10 seconds) could lead to a reduction in the marginal integrity in comparison to the recommended application time of 20 seconds.

[Direct adhesive reconstructions for restoration of posterior teeth with erosive tooth wear]. / Direkte Restaurationstechnik im Seitenzahnbereich zur Versorgung von erosionsbedingtem Zahnhartsubstanzverlust.

The restorative treatment of dental hard tissue loss, e.g., due to erosion, and the rehabilitation of the original vertical bite dimension confronts the dentist with problems when implementing the therapy. Traditionally, this therapy is conducted with laboratory-fabricated workpieces made of ceramics which usually require a preparation of the remaining tooth substance and also causes high costs for the patient. Therefore, alternative methods should be considered. This article presents the use of direct adhesive composite restorations as a way of reconstructing a dentition severely altered by erosion. To reconstruct the occlusal surfaces, transfer splints are used that are made on the basis of individual wax-up models. The procedure described is a well-researched and proven method for restoring teeth with erosion-related loss of hard tooth substance. As with all new procedures, there will be a certain learning curve for the practical dentist after which high-quality restorations can be implemented with this technique.

Effect of different adhesive application approaches on bond strength in over-etched dentin.

PURPOSE: To investigate the effect of over-etching and subsequent use of different adhesive application approaches including active, double, preheated, and ultrasonic application on dentin bond strength. METHODS: Dentin specimens from sound human third molars were prepared and allocated into six groups (n= 10 per group). In Group 1 (negative control), the dentin specimens were over-etched with phosphoric acid for 30 seconds, and a two-step etch-and-rinse adhesive (Prime & Bond XP; Dentsply Sirona) was applied for 20 seconds according to the manufacturer's instructions. In test Groups 2-5, the application of the adhesive varied: In Group 2, the adhesive was actively rubbed into the dentin surface, whereas in Group 3, a second adhesive layer was applied after light-curing of the first one. In Group 4, the adhesive was heated to 68°C prior to application, and in Group 5, the adhesive was ultrasonically activated. Acid-etching for 15 seconds and adhesive application for 20 seconds was performed in the positive control group (Group 6) according to the manufacturer's instructions. After light-curing and composite build-up [Ceram.x Spectra ST (HV); Dentsply Sirona], microtensile bond strength and fracture types were determined. Data were statistically analyzed by Kruskal-Wallis rank test, followed by post-hoc pairwise comparisons using Conover tests and P-value adjustment according to Holm (α= 0.05). RESULTS: Active, double, preheated, or ultrasonic adhesive application showed no significant effect on dentin bond strength when compared to the control groups. Predominantly adhesive failures were observed in all groups. CLINICAL SIGNIFICANCE: A modification of adhesive application by using active, double, preheated, or ultrasonic application does not improve bonding to accidentally over-etched dentin.

Effect of Toothbrush Bristle Stiffness and Brushing Force on Cleaning Efficacy.

PURPOSE: This study investigated the effect of toothbrush bristle stiffness and brushing force on the cleaning efficacy in vitro. MATERIALS AND METHODS: Eighty bovine dentin samples were allocated to eight groups (n=10). Two custom-made toothbrushes of different bristle stiffness (soft and medium) were tested at four different brushing forces (1, 2, 3 and 4 N). Dentin samples were stained in black tea and brushed (60 strokes/min) for a total of 25 min in a brushing machine with an abrasive solution (RDA 67). Photographs were taken after 2 and 25 min of brushing time. Cleaning efficacy was measured planimetrically. RESULTS: After 2 min of brushing, the soft-bristle toothbrush did not cause statistically significantly different cleaning efficacy at different brushing forces, while the medium-bristle toothbrush cleaned statistically significantly less efficaceously only at 1 N. Comparing the two different toothbrushes, higher cleaning efficacy was observed only at 1 N for the soft-bristle brush. At 25 min brushing time, the soft-bristle cleaned statistically significantly better at 4 N compared to 1 N and 2 N and at 3 N compared to 1 N. Using the medium-bristle, cleaning efficacy increased with increasing brushing force. After 25 min of brushing, no statistically significant difference was observed between the two different toothbrushes. CONCLUSION: Irrespective the brushing force, the use of a soft or medium toothbrush results in comparable cleaning efficacy. At 2 min brushing time, increasing the brushing force does not increase the cleaning efficacy.

Cleaning potential of interdental brushes around orthodontic brackets - an in vitro investigation.

This study evaluated the brushing efficacy of different interdental brushes around a multibracket appliance in vitro. In four models displaying misaligned and aligned teeth with and without attachment loss, the brushing capacities of three interdental brushes (IDB) were tested: A waist-shaped IDB with a diameter of 9 mm at both ends and 5 mm in the middle (B1), a cylindrical brush with a diameter of 9 mm (B2) and one with 5 mm (B3). Before cleaning, the black teeth in the respective models were stained white with titanium (IV) oxide and the percentage of cleaned surface was planimetrically assessed. In addition, the forces applied to the IDB were also recorded. The effect of brush and model on expected cleaning performance was examined using an analysis of variance (ANOVA). The cleaning performance of the brushes in decreasing order was B2>B3>B1; no significant differences between the different tooth areas and models were found. With regard to force measurements, significant differences were found with the highest and lowest forces IDB (2) and (1), respectively. There was a significant correlation between force and cleaning performance: The higher the force needed the higher was the cleaning performance. In summary, this study showed that cylindrical interdental brushes achieved a better cleaning performance than the waist-shaped IDB. Given some shortcomings of this first laboratory study, more research is still needed, but IDB may represent a valuable yet still clinically underused tools.

Antibiotic Resistance among Fusobacterium, Capnocytophaga, and Leptotrichia Species of the Oral Cavity.

PURPOSE: Antibiotics play an important role in treating periodontal diseases. Due to the effectiveness of antibiotic therapies, their usage in dentistry has significantly increased. The aim of this study focused on the in-vitro susceptibility of different gram-negative oral bacteria species - which are associated with periodontal diseases (Fusobacterium spp., Capnocytophaga spp. and Leptotrichia buccalis) and have different geographical origins (Asia and Europe) - against antimicrobials that are clinically relevant in dental therapy. MATERIALS AND METHODS: A total of 45 strains were tested (29 Fusobacterium spp., 13 Capnocytophaga spp. and 3 L. buccalis) that were either isolated from Chinese patients or were obtained from different strain collections. Their antimicrobial susceptibility to the antimicrobial agents benzylpenicillin, amoxicillin, amoxicillin-clavulanic acid, ciprofloxacin, moxifloxacin, clindamycin, doxycycline, tetracycline and metronidazole was tested using the E-Test. Strains with particular resistance to penicillin, clindamycin and metronidazole were further analysed for resistance genes. RESULTS: All tested bacterial isolates were sensitive to amoxicillin, amoxicillin-clavulanic acid, doxycycline and tetracycline, but showed variable sensitivity towards other antibiotics such as benzylpenicillin, ciprofloxacin, moxifloxacin, clindamycin and metronidazole. CONCLUSION: The results of the present study suggest that certain periodontal disease-related bacterial strains can be resistant towards antimicrobial agents commonly used in adjuvant periodontal therapy.

Effect of polymerization mode on shrinkage kinetics and degree of conversion of dual-curing bulk-fill resin composites.

OBJECTIVES: To assess the behavior of dual-cure and conventional bulk-fill composite materials on real-time linear shrinkage, shrinkage stress, and degree of conversion. MATERIALS AND METHODS: Two dual-cure bulk-fill materials (Cention, Ivoclar Vivadent (with ion-releasing properties) and Fill-Up!, Coltene) and two conventional bulk-fill composites (Tetric PowerFill, Ivoclar Vivadent; SDR flow + , Dentsply Sirona) were compared to conventional reference materials (Ceram.x Spectra ST (HV), Dentsply Sirona; X-flow; Dentsply Sirona). Light curing was performed for 20 s, or specimens were left to self-cure only. Linear shrinkage, shrinkage stress, and degree of conversion were measured in real time for 4 h (n = 8 per group), and kinetic parameters were determined for shrinkage stress and degree of conversion. Data were statistically analyzed by ANOVA followed by post hoc tests (α = 0.05). Pearson's analysis was used for correlating linear shrinkage and shrinkage force. RESULTS: Significantly higher linear shrinkage and shrinkage stress were found for the low-viscosity materials compared to the high-viscosity materials. No significant difference in degree of conversion was revealed between the polymerization modes of the dual-cure bulk-fill composite Fill-Up!, but the time to achieve maximum polymerization rate was significantly longer for the self-cure mode. Significant differences in degree of conversion were however found between the polymerization modes of the ion-releasing bulk-fill material Cention, which also exhibited the significantly slowest polymerization rate of all materials when chemically cured. CONCLUSIONS: While some of the parameters tested were found to be consistent across all materials studied, heterogeneity increased for others. CLINICAL RELEVANCE: With the introduction of new classes of composite materials, predicting the effects of individual parameters on final clinically relevant properties becomes more difficult.

Abrasive Enamel and Dentin Wear Resulting from Brushing with Toothpastes with Highly Discrepant Relative Enamel Abrasivity (REA) and Relative Dentin Abrasivity (RDA) Values.

PURPOSE: To investigate the absolute wear caused by toothpastes with highly discrepant REA (Relative Enamel Abrasivity) and RDA (Relative Dentin Abrasivity) values on both enamel and dentin: Candida Peppermint (CP; REA: 1; RDA: 42), Colgate Total Original (CTO; REA: 4; RDA: 100), Signal White System (SWS; REA: 8; RDA: 143), and Candida White Diamond (CWD; REA 244; RDA: 12). MATERIALS AND METHODS: Eighty (80) bovine enamel samples and 80 dentin samples were divided into four groups each (n = 20) and investigated after a 6-h brushing procedure (21,600 cycles, 60 cycles/min, load of 2.5 N) with the four toothpastes. The abrasive enamel and dentin wear were registered using a contact profilometer. The median and interquartile range (IQR) of the abrasive enamel and dentin wear were calculated for each group. Pairwise comparisons were conducted using the Wilcoxon signed-rank exact test, and the p-value was adjusted according to Holm (statistical significance set at 0.05). RESULTS: CWD led to the highest abrasive enamel wear (9.86 µm [5.77]). CTO caused the highest abrasive dentin wear (166.70 µm [69.90]), being statistically significantly higher than the wear for CP (54.20 µm [24.00]) and CWD (17.00 µm [7.80]) (p = 0.00001). The abrasive dentin wear for CWD was statistically significantly lower in comparison to all other groups (p = 0.00001). CONCLUSION: Toothpastes with highly discrepant REA and RDA values presented statistically significantly different absolute wear on enamel and dentin. REA and RDA values should both be declared for every toothpaste.

In vitro versus in situ biofilms for evaluating the antimicrobial effectiveness of herbal mouthrinses.

For centuries, diverse mouthrinses have been applied for medicinal purposes in the oral cavity. In view of the growing resistance of oral microorganisms against conventional antimicrobial agents e.g. chlorhexidine, the implementation of alternative treatments inspired by nature has lately gained increasing interest. The aim of the present study was to compare in vitro biofilm models with in situ biofilms in order to evaluate the antimicrobial potential of different natural mouthrinses. For the in vitro study a six-species supragingival biofilm model containing A. oris, V. dispar, C. albicans, F. nucleatum, S. mutans and S. oralis was used. Biofilms were grown anaerobically on hydroxyapatite discs and treated with natural mouthrinses Ratanhia, Trybol and Tebodont. 0.9% NaCl and 10% ethanol served as negative controls, while 0.2% CHX served as positive control. After 64h hours, biofilms were harvested and quantified by cultural analysis CFU. For the in situ study, individual test splints were manufactured for the participants. After 2h and 72h the biofilm-covered samples were removed and treated with the mouthrinses and controls mentioned above. The biofilms were quantified by CFU and stained for vitality under the confocal laser scanning microscope. In the in vitro study, 0.2% CHX yielded the highest antimicrobial effect. Among all mouthrinses, Tebodont (4.708 ± 1.294 log10 CFU, median 5.279, p<0.0001) compared with 0.9% NaCl showed the highest antimicrobial potential. After 72h there was no significant reduction in CFU after 0.2% CHX treatment. Only Trybol showed a statistically significant reduction of aerobic growth of microorganisms in situ (5.331 ± 0.7350 log10 CFU, median 5.579, p<0.0209). After treatment with the positive control 0.2% CHX, a significant percentage of non-vital bacteria (42.006 ± 12.173 log10 CFU, median 42.150) was detected. To sum up, a less pronounced effect of all mouthrinses was shown for the in situ biofilms compared to the in vitro biofilms.

Quality of CAD-CAM inlays placed on aged resin-based composite restorations used as deep margin elevation: a laboratory study.

OBJECTIVES: To assess the impact of the age of resin-based composite (RBC) restorations used for deep margin elevation (DME) on the marginal quality and fracture resistance of inlays. MATERIALS AND METHODS: Permanent human molars with direct RBC restorations, involving the mesial, occlusal, and distal surface (MOD), were allocated to four groups (each n = 12). Half of the teeth underwent thermomechanical loading including 240,000 occlusal load cycles and 534 thermal cycles (TML, 5 °C/55 °C; 49 N, 1.7 Hz). With RBC left in one proximal box as DME, all teeth received MOD inlays, made from lithium disilicate (LDS) or a polymer-infiltrated ceramic network material (PICN). The restored teeth underwent TML including 1.2 million occlusal cyclic loadings and 2673 thermal cycles. The marginal quality was assessed at baseline and after both runs of TML. Load-to-fracture tests were performed. The statistical analysis comprised multiple linear regressions (α = 0.05). RESULTS: Simulated aging of RBC restorations had no significant effect on the marginal quality at the interface between the RBC and the tooth and the RBC and the inlay (p ≥ 0.247). Across time points, higher percentages of non-continuous margin were observed between the inlay and the tooth than between the tooth and the RBC (p ≤ 0.039). The age of the DME did not significantly affect the fracture resistance (p ≥ 0.052). CONCLUSIONS: Artificial aging of RBC restorations used for DME had no detrimental effect on the marginal quality and fracture resistance of LDS and PICN inlays. CLINICAL RELEVANCE: This laboratory study suggests that-in select cases-intact, direct RBC restorations not placed immediately before the delivery of an indirect restoration may be used for DME.