Efficiency of mixed and rigid occlusal stabilization splints: Randomized clinical trial.

Occlusal stabilization splints are the most common treatment for controlling the deleterious effects of sleep bruxism. This study aimed to evaluate the effectiveness of a low-cost, mixed occlusal splint (MOS) compared to that of a rigid splint. A randomized clinical trial was performed on 43 adults of both sexes with possible sleep bruxism and satisfactory dental conditions. They were divided into rigid occlusal splint (ROS) (n = 23) and MOS (n = 20) groups. Masticatory muscle and temporomandibular joint (TMJ) pain intensity (visual analog scale), quality of life (WHOQOL-BREF), indentations in the oral mucosa, anxiety, and depression (HADS), number of days of splint use, and splint wear were evaluated. All variables were evaluated at baseline (T0), 6 months (T6), and 12 months (T12) after splint installation (T0), and splint wear was evaluated at T6 and T12. Student's t-test, Mann-Whitney U test, non-parametric Friedman's analysis of variance for paired samples and pairwise multiple comparisons, Pearson's chi-square test, two-proportion z-test, non-parametric McNemar's and Cochran's Q, and Wilcoxon tests were used (p < 0.05). In both groups, there was a decrease in TMJ pain and pain intensity over time and improvements in the quality of life scores. At T6, there was a higher rate of splint wear in the MOS group than in the ROS group (p = 0.023). The MOS showed a higher rate of wear than the rigid splint but had similar results for the other variables. Therefore, the use of a mixed splint appears to be effective in controlling the signs and symptoms of sleep bruxism.

Bond strength of prefabricated and CAD-CAM milled glass fiber post-and-cores luted with conventional, universal, and self-adhesive composite resin cement.

STATEMENT OF PROBLEM: Little is known about the effect of different composite resin cements on the bond strength of prefabricated and milled glass fiber post-and-cores. PURPOSE: The purpose of this in vitro study was to compare the push-out bond strengths of root dentin and standard, relined, or computer-aided design and computer-aided manufacturing (CAD-CAM) glass fiber post-and-cores luted with conventional, universal, or self-adhesive composite resin cement. MATERIAL AND METHODS: Post spaces were prepared in 90 premolars. Standard and relined prefabricated and CAD-CAM-milled glass fiber post-and-cores were luted with conventional (RelyX ARC; 3M ESPE), universal (RelyX Ultimate; 3M ESPE), and self-adhesive (RelyX U200; 3M ESPE) composite resin cement (n=10). All specimens were thermally aged (5000 cycles at 5°C and 55°C with a 20-second dwell time) and mechanical fatigue (1 000 000 cycles at 2 Hz, 50-N load). The specimens were sectioned perpendicularly to the root long axis into 1-mm-thick sections (apical, middle, and cervical root thirds), the push-out bond strength was determined, and the mode of failure recorded. Data were submitted to the Kruskal-Wallis test followed by the Bonferroni-Dunn multiple comparison test (α=.05). RESULTS: Push-out bond strength values did not differ (P>.05) among posts at the same root thirds. Standard posts showed higher bond strength than CAD-CAM at the apical third for data grouped by composite resin cements (P<.001). The cervical root thirds had higher bond strength than the apical thirds (P<.05). The cervical, middle, and apical root thirds showed decreasing bond strength values for each type of post for data grouped by composite resin cement (P<.001). Adhesive failures at the dentin-cement interface were predominant. CONCLUSIONS: The type of posts and cements did not affect the bond strength of glass fiber posts. The cervical root thirds had better bonding performance than the apical thirds.

Efficiency of mixed and rigid occlusal stabilization splints: Randomized clinical trial

Abstract Occlusal stabilization splints are the most common treatment for controlling the deleterious effects of sleep bruxism. This study aimed to evaluate the effectiveness of a low-cost, mixed occlusal splint (MOS) compared to that of a rigid splint. A randomized clinical trial was performed on 43 adults of both sexes with possible sleep bruxism and satisfactory dental conditions. They were divided into rigid occlusal splint (ROS) (n = 23) and MOS (n = 20) groups. Masticatory muscle and temporomandibular joint (TMJ) pain intensity (visual analog scale), quality of life (WHOQOL-BREF), indentations in the oral mucosa, anxiety, and depression (HADS), number of days of splint use, and splint wear were evaluated. All variables were evaluated at baseline (T0), 6 months (T6), and 12 months (T12) after splint installation (T0), and splint wear was evaluated at T6 and T12. Student's t-test, Mann-Whitney U test, non-parametric Friedman's analysis of variance for paired samples and pairwise multiple comparisons, Pearson's chi-square test, two-proportion z-test, non-parametric McNemar's and Cochran's Q, and Wilcoxon tests were used (p < 0.05). In both groups, there was a decrease in TMJ pain and pain intensity over time and improvements in the quality of life scores. At T6, there was a higher rate of splint wear in the MOS group than in the ROS group (p = 0.023). The MOS showed a higher rate of wear than the rigid splint but had similar results for the other variables. Therefore, the use of a mixed splint appears to be effective in controlling the signs and symptoms of sleep bruxism.

Psychometric Properties of Food Frequency Questionnaires Used in Dentistry: A Systematic Review.

The objective of this systematic review was to analyze the quality of the food frequency instruments/scales used in dentistry while considering their psychometric properties. The databases consulted were PubMed (August 7, 2020), Scopus (August 27, 2020), Web of Science (August 27, 2020), Cumulative Index to Nursing and Allied Health Literature (CINAHL) and Dentistry and Oral Sciences Source (via EBSCO) (August 28, 2020), LILACS and BBO (August 25, 2020), gray literature: Proquest (October 1, 2020), Capes Theses Bank (October 1, 2020), Brazilian Digital Library of Theses and Dissertations (October 1, 2020), Google Scholar (October 2, 2020), and proceedings of the International Association for Dental Research (IADR) (October 10, 2020). All databases were updated on December 12, 2022. Articles were initially selected by reading the 6,421 titles and 13 abstracts selected, followed by reading the 8 articles included for full text reading to confirm the eligibility criteria, with the aid of Rayyan software. Databases of the construction and/or validation of instruments/scales for assessing food consumption for use in dentistry (in clinical contexts and/or epidemiological studies), with or without assessment of their psychometric properties, were included. Review studies, letters to editors, and research protocols were excluded. Risk of bias assessment was performed according to the Consensus-Based Standards for the Selection of Health Measurement Instruments (COSMIN) checklist. The extracted data were author, country, instrument language, sample, assessment instrument, instrument structure, type of food, instruments compared with the clinical condition, adaptation of an existing instrument, and psychometric properties evaluated. The selection, risk of bias analysis, and data extraction processes were performed by two independent evaluators. Seven studies were identified. The instruments available in the literature were in English, Japanese, Creole, and Malay. Only one study performed translation and cross-cultural validation of an instrument, whereas the others were construction studies. One study did not assess psychometric properties. Regarding the quality assessment and general classification of the studies by the COSMIN checklist, all were considered "inadequate," with reliability (test-retest) being the most validated psychometric property; only one study carried out the validation of all psychometric properties measured in COSMIN. Regarding the quality of the instruments presented, all the studies were classified as "inadequate" in the general assessment. Advances are needed in the validation process.

Fracture strength, pull-out bond strength, and volume of luting agent of tooth-colored CAD-CAM post-and-cores.

STATEMENT OF PROBLEM: Little is known about the fracture strength, retention, and adaptation of post-and-cores fabricated with novel tooth-colored materials by computer-aided design and computer-aided manufacturing (CAD-CAM). PURPOSE: The purpose of this in vitro study was to investigate the fracture strength, pull-out bond strength (POBS), and volume of luting agent of endodontically treated premolars restored with post-and-cores milled from different CAD-CAM materials. MATERIAL AND METHODS: Post spaces were prepared in 80 human premolars in which post-and-cores fabricated with polyetheretherketone (PK; Ceramill PEEK), nanohybrid composite resin (BB; Brava Block), polymer-infiltrated ceramic (EN; VITA Enamic), and fiber-reinforced epoxy resin (GF; Fiber Cad Post & Core) CAD-CAM materials were luted (n=20). All specimens were subjected to thermal aging (3000 cycles at 5 °C and 55 °C with a 20-second dwell time). Half of the specimens were subjected to mechanical fatigue (250 000 cycles at 5 Hz) before fracture strength testing, while the other half was submitted to POBS testing and volume of luting agent measurement. Fracture strength data were analyzed by 1-way ANOVA, while POBS and volume of luting agent data were submitted to Kruskal-Wallis followed by the Bonferroni-Dunn multiple comparison tests. The correlation between POBS and the volume of luting agent was determined by the Spearman test (α=.05). RESULTS: POBS of GF was significantly higher than that for PK (P<.001); however, failure load (P=.160) and volume of luting agent (P=.390) values did not differ. EN showed the highest percentage of catastrophic failures (20%), while PK exhibited only core deformations. POBS and cement film volume were not significantly correlated (P>.05). CONCLUSIONS: Different CAD-CAM materials did not influence the fracture strength and volume of luting agent of post-and-cores. Post-and-cores made with PEEK blocks showed lower bond strength to intracanal dentin than those made with fiber-reinforced epoxy resin blocks. No significant correlation was found between bond strength and the volume of luting agent.

Influence of cervical margin relocation with direct restorative materials on the marginal integrity of CAD-CAM composite inlays.

PURPOSE: To evaluate the in vitro marginal integrity of CAD-CAM composite inlays with the proximal box margin relocated with different direct restorative materials before and after thermomechanical aging. METHODS: Standardized 4 mm-wide Class II cavities were prepared in 40 sound human upper molars. The mesial cervical margin was located in enamel (control) and 1 mm occlusal to the cemento-enamel junction (CEJ), while the distal cervical margin was located in dentin (experimental) and 2 mm apical to the CEJ. In the experimental groups (n=10), the distal margins were relocated up to the CEJ level by using a highly viscous conventional glass ionomer cement (Equia Forte), low-viscosity bulk-fill composite (SureFil SDR Flow), highly viscous nanofilled composite (Filtek Supreme XT), or a highly viscous bulk-fill composite (Filtek Bulk Fill). The inlays were milled from CAD-CAM nanohybrid composite blocks (Brava Block) and luted with dual-cure resin cement (Allcem). The specimens were submitted to thermocycling (5-55°C, 7,800 cycles) and fatigue loading (50 N, 1 Hz, 240,000 cycles). Epoxy resin replicas of the margins were obtained before and after aging and evaluated through scanning electron microscopy. The percentage of continuous margin in relation to individual assessable margin was calculated as the marginal integrity. The data were statistically analyzed using Wilcoxon and Kruskal-Wallis tests (α= .05). RESULTS: The marginal integrity before and after aging was not significantly different (P> 0.05). Similarly, no significant differences were observed between margins relocated with different restorative materials in comparison to enamel margins (P> 0.05). CLINICAL SIGNIFICANCE: Cervical margin relocation is a valid protocol to simplify intra-oral scanning and luting of CAD-CAM composite inlays with deep proximal margins. The marginal integrity at deep margins with relocation material was comparable to that of enamel margins.

Randomized clinical trial of complete denture cleaning methods in residents of care institutions

Aim: To evaluate the efficacy of ultrasonic bath and traditional brushing in the hygiene of complete dentures of dependent residents in long-term care institutions (LTCIs). Methods: A randomized cross-over clinical study was conducted in 17 maxillary complete denture wearers living in LTCIs. Cleaning protocols were brushing or ultrasonic bath, both applied with neutral liquid soap. Biofilm biomass were estimated by MTT reduction assay and specific microbial load (CFU) of Streptococcus spp., Staphylococcus spp. and Candida spp. were quantified by selective and differential culture media. Results: Ultrasound method showed higher percentage reduction of biofilm biomass and specific microbial loads of Streptococcus spp. compared to brushing (p<0.01). Reduction of microbial loads of the other microorganisms were not different between cleaning methods (p>0.05). Conclusions: The ultrasonic bath proved to be a feasible alternative method for the mechanical cleaning of complete dentures in LTCIs

Finite Element Analysis of a Controlled Dynamization Device for External Circular Fixation.

Objective To virtually prototype a device for external circular fixation of long bone fractures with controlled dynamization made of two different materials and predict their mechanical behavior by using the finite element analysis (FEA) method. Method A software was used for 3D modeling two metal parts closely attached by a sliding dovetail joint and a high-density silicone damper. Distinctive FEAs were simulated by considering two different materials (stainless steel or titanium), modes (locked or dynamized) and loading conditions (static/point or dynamic/0.5 sec) with uniform 150 kg axial load on top of the device. Results The finite elements (FEs) model presented 81,872 nodes and 45,922 elements. Considering stainless steel, the maximum stress peak (140.98 MPa) was reached with the device locked under static loading, while the greatest displacement (2.415 × 10 -3 mm) was observed with the device locked and under dynamic loading. Regarding titanium, the device presented the maximum stress peak (141.45 MPa) under static loading and with the device locked, while the greatest displacement (3.975 × 10 -3 mm) was found with the device locked and under dynamic loading. Conclusion The prototyped device played the role of stress support with acceptable deformation in both locked and dynamized modes and may be fabricated with both stainless steel and titanium.

Effect of half-digital workflows on the adaptation of custom CAD-CAM composite post-and-cores.

STATEMENT OF PROBLEM: Even without the use of an intraoral scanner, post-and-cores can be obtained by using a part-digital fabrication workflow that requires pattern modeling (direct, indirect, or impression); however, studies on the adaptation of computer-aided design and computer-aided manufacturing (CAD-CAM) composite resin post-and-cores in comparison with metal cast post-and-cores are sparse. PURPOSE: The purpose of this in vitro study was to analyze the adaptation of CAD-CAM composite resin post-and-cores fabricated through a part-digital fabrication workflow and to compare it with that of metal cast post-and-cores fabricated through conventional methods. METHOD AND MATERIALS: Eight extracted human premolars were endodontically treated and prepared for custom post-and-cores. Metal cast post-and-cores were fabricated with Ni-Cr alloy (Fit Cast-Sb Plus; Talmax) and conventional resin pattern modeling methods directly in the root canal (conventional direct modeling) or indirectly in a stone cast (conventional indirect modeling). Composite resin post-and-cores were milled from nanohybrid glass-ceramic composite resin CAD-CAM blocks (Brava Block; FGM) by using the part-digital workflow. A laboratory scanner was used to digitalize polyvinyl siloxane impressions (part-digital scanned impression direct CAD-CAM [PSC]) of the root canals and resin patterns fabricated directly (part-digital direct CAD-CAM [PDC]) or indirectly (part-digital indirect CAD-CAM [PIC]). All post-and-cores were placed in the respectively prepared root canals, scanned with microcomputed tomography, and measured in terms of volume of the cementation space, the luting cement film thickness in each root third, and the apical gap between the apical end of the post-and-cores and remaining gutta percha (apical gap). The groups were compared for each adaptation parameter by using 2-way (volume of the cementation space and apical gap) and 3-way (film thickness) ANOVA, and the Games-Howell multicomparison post hoc test (α=.05). RESULTS: The conventional direct modeling group had lower mean volume of the cementation space than all CAD-CAM composite resin post-and-cores (P<.041). The conventional indirect modeling group had a lower volume of the cementation space mean than PDC (P<.024) but was not significantly different from PIC (P=.577) or PSC (P=.221). Regardless of the fabrication workflow, no differences were observed among the CAD-CAM composite resin post-and-cores (P>.05). At the apical root third, conventional direct modeling and conventional indirect modeling had lower film thickness means than PSC or PDC (P<.05). In the middle third, conventional direct modeling and conventional indirect modeling had lower film thickness means than PDC (P≤.001). At the cervical third, no differences in film thickness means were observed among the groups (P>.05). PDC had a lower apical gap mean than PSC (P=.013), while no significant differences were found for other pair comparisons (P>.05). CONCLUSIONS: Metal post-and-cores had slightly better adaptation than the CAD-CAM composite resin post-and-cores; however, the part-digital fabrication workflow of CAD-CAM composite resin post-and-cores provided adaptation parameters within a clinically acceptable range and is less time consuming.

Reliability and correlation between microshear and microtensile bond strength tests of composite repairs.

The aim of this study was to evaluate the reliability of microshear (µSBS) and microtensile (µTBS) bond strength tests on composite repairs using universal adhesives with or without the application of additional silane. Cylindrical (µSBS) and block-shaped (µTBS) specimens were fabricated using nanofilled (F-Filtek One Bulk Fill) and nanohybrid (T-Tetric EvoCeram Bulk Fill) bulk-fill composites. The specimens were aged by thermocycling (5,000 cycles, 5-55 °C), sandblasted, and then divided into three groups (n = 30) as follows: non-repaired (FC and TC), repaired with universal adhesives (FA, Scotchbond Universal; and TA, Adhese Universal), and with the previous application of silane (FS and TS). After 48 h, the specimens were repaired using the same composite. The µSBS and µTBS specimens exhibited bonded areas of 1 mm2 and were subjected to shear stress and tension until failure, at a crosshead speed of 0.5 mm/min in a universal testing machine. Weibull analyses and Pearson correlation (α = 0.05) were applied to the data. At characteristic strength, FC, FA, and FS exhibited significantly higher µSBS when compared with TA and TS (p < 0.05). However when tested by µTBS at the same parameter, FA presented significantly lower bond strength when compared to FC, FS, and TA (p < 0.05). The correlation between Weibull modulus was strongly negative and not significant (p > 0.05). Both bond strength tests exhibited a material-dependent behavior. The microtensile bond strength test demonstrated more reliability than the microshear test for composite repair evaluation.

The Eye-Tracking Study of the Impact of the Gingival Margin Height of Maxillary Lateral Incisors.

The objective of this study was to verify differences in eye-tracking metrics and subjective smile esthetic ratings between general practitioners, orthodontists, and laypersons in cases of maxillary lateral incisor gingival margin deviations. Unilateral apical and incisal gingival margin deviations of 1, 2, and 3 mm were digitally produced in pictures of a man and a woman smiling. Specific areas of interest (AOIs) were created in each picture. Eye-tracking metric data included the time to first fixation (TFF) and number of fixations (NF). A specific sensor and software were used to acquire information on the eye movements. Data on the smile esthetic ratings were obtained using a visual analog scale (VAS). Analysis of variance and Pearson correlation were applied. The TFF on the AOIs in the mouth was shorter for general practitioners and orthodontists, signifying that general practitioners and orthodontists rapidly perceived the features in these areas, while for laypersons, the TFF was shorter for the AOIs of the eyes (P < .05). The NF was greater on the AOIs in the mouth for general practitioners and orthodontists, whereas to the laypersons, the NF tended to be greater on the AOIs in the eyes. Mean VAS scores differed between observer groups (P < .05). For the male picture, the 1-mm and 2-mm apical gingival margin deviations received the highest scores from the laypersons, while for both female and male pictures, the 1-mm apical deviation received the highest scores from the general practitioners and orthodontists. Higher VAS scores resulted in longer times that general practitioners and orthodontists spent looking at the gingival margin changes. General practitioners and orthodontists differ from laypersons in their perceptions of smile esthetics. Eye-tracking metrics revealed that the AOIs in the mouth aroused greater interest from the general practitioners and orthodontists, and this interest became greater as the gingival margin deviations increased to 3 mm. Laypersons fixated more on the AOIs of the eyes. The VAS scores indicated that general practitioners and orthodontists were more critical than laypersons, accepting smaller deviations in the gingival margins of the maxillary lateral incisors.

Prevalence of temporomandibular disorders in rugby players.

Rugby is played by more than 3 million people in over 100 countries on 5 continents. Playing rugby can result in 2-3 times more dental and facial trauma than American football or other contact sports. Facial trauma in sports has been associated with the development of temporomandibular disorders (TMDs). This study aimed to determine the prevalence of TMDs in rugby players. The Research Diagnostic Criteria for Temporomandibular Disorders were used to assess 30 rugby players (group 1) and 28 nonathletes (group 2) for TMDs. The chi-square test was used to compare the groups, and a significance level of 5% (P < 0.05) was used for all statistical analyses. The prevalence of TMDs in groups 1 and 2 was 53.3% and 14.3%, respectively (P = 0.002). Myofascial pain was observed in 12 individuals (40%) in group 1 and in 2 individuals (7.1%) in group 2. Seven participants in group 1 (23.3%) received a diagnosis of disc displacement, and 2 participants (7.1%) in group 2 received this diagnosis. Participants in group 1 also reported significantly more tooth clenching than those in group 2 (P = 0.003).

A 3D finite element analysis of glass fiber reinforcement designs on the stress of an implant-supported overdenture.

STATEMENT OF PROBLEM: Evidence regarding the effect of different glass fiber reinforcement designs on the biomechanical behavior of implant-supported overdentures is lacking. PURPOSE: The purpose of this finite element analysis was to analyze the stress distribution in an implant-supported overdenture reinforced with a cast metal reinforcement bar and 4 different designs of unidirectional glass fiber to minimize the risk of denture base fracture. MATERIAL AND METHODS: A 3D edentulous mandible incorporating an implant-supported overdenture model without reinforcement (control, CT) or reinforced with 1 cast metal bar reinforcement (CM) was placed over the top of the implants and 4 unidirectional glass fiber reinforcements. The glass fiber bundle was placed over the top of the implants (GF), or 2 bundled halves were placed over the top (GO) of, between (GB), or distal (GD) to implants. Three patterns of occlusal loading were simulated: L1, all artificial teeth loaded in the long axis; L2, all left-side teeth loaded in the long axis; and L3, posterior left-side teeth loaded obliquely (45 degrees). RESULTS: Under L1 and L3, the tensile stresses were higher for CT, GD, and GO and lower for GF and CM. Under L2, no differences were seen between groups. Stresses were concentrated on the periphery of the O-ring connector, on the basal area, and on the middle-lingual region of the overdenture. CONCLUSIONS: Reinforcements placed in the middle region and over the top of the implants provided better load distribution. Unidirectional glass fiber behaved as cast metal when used to reinforce the implant-supported overdenture.

Scanning of root canal impression for the fabrication of a resin CAD-CAM-customized post-and-core.

Customization of post-and-cores using computer-aided design and computer-aided manufacturing (CAD-CAM) requires the scanning of a pattern and the subsequent digital design. This technique describes a method of fabricating a CAD-CAM-customized post-and-core designed from a scanned polyvinyl siloxane impression and milled from a nanoparticle/nanocluster-filled resin block. The polyvinyl siloxane impression allowed a faster and more efficient customization of the CAD-CAM post-and-core than a conventional acrylic resin pattern. The properties of the nanoparticle/nanocluster filled resin block make the material suitable for chairside CAD-CAM post-and-core fabrication.

Effect of CAD/CAM glass fiber post-core on cement micromorphology and fracture resistance of endodontically treated roots.

PURPOSE: To investigate the fracture resistance of weakened roots restored with prefabricated or CAD/CAM-customized posts and cores as well as the thickness of the cement film and the presence of voids in the cement. METHODS: The roots of 40 human premolars were weakened by removing internal dentin with a diamond bur (2.5 mm in the coronal third and 1.5 mm in the apical third) and restored with prefabricated posts (PPs) or customized posts (CPs) with or without a zirconia crown (n= 10). Posts and crowns were cemented with resin cement. Microtomography was used to determine the thickness of the cement film and whether voids were present. After fatigue testing (1 million cycles, 50 N, 5 Hz, 36.5°C), the specimens underwent compression testing with an oblique load (30°, 1 mm/minute) and fracture strengths were recorded (N). Fracture strength and film thickness were analyzed with ANOVA and the Games-Howell test; the variable presence of voids was analyzed with the Mann-Whitney test (α= 5%). RESULTS: Mean fracture strengths varied between 640.4 and 792.9 N and did not differ significantly between groups. The CP group had a thinner cement film and fewer voids than the PP group. There was a positive, statistically significant correlation (Spearman, R=0.488, P= 0.029) between these variables. CLINICAL SIGNIFICANCE: CAD/CAM-manufactured glass-fiber posts and cores do not affect the fracture strength of flared root canals or cause catastrophic failure of the root when used with zirconia crowns.

Effect of organic solvents compared to sandblasting on the repair bond strength of nanohybrid and nanofilled composite resins.

BACKGROUND: This study evaluated the effect of different surface treatments on the repair bond strength of nanohybrid (Empress Direct) and nanofilled (Filtek Z350 XT) composite resins. MATERIALS AND METHODS: A total of 120 specimens of each material (7.5 x 4.5 x 3 mm) were prepared and polished with SiC paper. Half of the specimens were kept in water for seven days and the other half for six months; they were then divided into six groups according to the type of surface treatment: negative control (no treatment), Al2O3sandblasted, liquid acetone, acetone gel, liquid alcohol and alcohol gel. Following application of the silane coupling agent and the adhesive system, composite resin cylinders were fabricated on the specimens and light cured (20 seconds). The same composite resins were used for the repair. Additionally, ten intact specimens of each composite resin (without repair) were prepared (positive control). The specimens were then loaded to failure in the microshear mode. Three additional specimens were fabricated in each group, and the surface treatments were analyzed by atomic force microscopy, energy-dispersive X-ray spectroscopy (EDS) and scanning electron microscopy (SEM). RESULTS: The nanofilled composite resin showed higher cohesive strength and repair bond strength than the nanohybrid composite resin. The aging process affected the repair bond strength of the nanofilled composite resin. Al2O3sandblasting was more efficient for the nanofilled composite resin and promoted greater surface roughness in both materials. The solvents demonstrated higher efficacy for the nanohybrid composite resin. CONCLUSION: The strengths resulting from the solvents were material dependent, and Al2O3sandblasting resulted in superior repair bond strength in both materials.

Comparative study of the fluorescence intensity of dental composites and human teeth submitted to artificial aging.

The aim of this study was to evaluate quantitatively the fluorescence of resin composites and human teeth, and to determine the stability of fluorescence after aging. Ten specimens were built using a 1 mm thick increment of dentin composite overlapped by a 0.5 mm thick increment of enamel composite. Ten sound human molars were sectioned and silicon carbide-polished to obtain enamel and dentin slabs 1.5 mm in thickness. Fluorescence measurements were carried out by a fluorescence spectrophotometer before and after thermocycling (2000 cycles, 5°C and 55°C). One-way analysis of variance (ANOVA) with repeated measures and Tukey's test were performed at a significance level of 5%. Most of the tested composites showed significant differences in fluorescence both before and after aging (P < 0.05). Opallis was the only composite whose fluorescence was similar to that of human teeth at both periods of evaluation (P > 0.05), and was the only composite that showed comparable results of fluorescence to the tooth structure before and after thermocycling. With the exception of Filtek Supreme, there were significant reductions in fluorescence intensity for all the tested composites (P < 0.05).

Anaerobic enhancement of protease secretion by periodontal Candida albicans strains / Aumento anaeróbio da secreção de protease pelas cepas de Candida albicans periodontal

Among other non-bacterial organisms, yeasts have been isolated from subgingival sites with relative frequency. Candida albicans is the species most commonly isolated although its role in periodontal disease has not been established. Objective: This study evaluated the secretion patterns of aspartyl-protease (Sap) by periodontal and nonperiodontal Candida albicans strains in normoxic and anoxic conditions. Material and methods: Periodontal strains (n=10; periodontal pockets ≥3.00 mm) and nonperiodontal Candida albicans strains (n=10) were grown under normoxic and anoxic conditions in protease-inducible broth. Sap activities were quantified in supernatants using azocasein as substrate. Whole-protein contents in supernatants were determined by Bradford’s method. Specific protease activities (Sap activity.protein-1) were assessed and compared. Results: While nonperiodontal strains secrete similar amounts of Sap under both atmospheric conditions, periodontal strains secrete reduced amounts in the presence of molecular oxygen. Conclusion: Despite the limited number of assayed isolates, the possibilities of adaptation or selection of candidal strains to periodontal microenvironment may be considered...

Entre organismos não bacterianos, as leveduras têm sido isoladas de sítios subgengivais com relativa frequência. Candida albicans é a espécie mais comumente isolada, embora seu papel na doença periodontal não esteja estabelecido. Objetivo: Este estudo avaliou os padrões de secreção de aspartil-protease (Sap) por cepas periodontais e não periodontais de Candida albicans em situações de normóxia e anóxia. Material e métodos: Cepas periodontais (n=10; bolsas periodontais ≥3,00 milímetros) e cepas de não periodontais (n=10) Candida albicans foram cultivadas sob condições normóxicas e anóxicas em caldo de protease-induzida. A atividade Sap foi quantificada em sobrenadantes utilizando azocaseína como substrato. O conteúdo de proteínas totais nos sobrenadantes foi determinado pelo método de Bradford. Atividades de protease específica (atividade de proteína Sap-1) foram avaliadas e comparadas. Resultados: Apesar das cepas não periodontais secre¬tarem quantidades semelhantes de Sap em ambas as condições atmosféricas, as cepas periodontais secretam quantidades reduzidas na presença de oxigênio molecular. Conclusão: Apesar do número limitado de amostras analisadas, as possibilidades de adaptação ou seleção de cepas de Candida no microambiente periodontal pode ser considerada...

The effect of at-home bleaching and toothbrushing on removal of coffee and cigarette smoke stains and color stability of enamel.

BACKGROUND: The authors conducted a study to evaluate the stain removal ability of tooth bleaching and simulated toothbrushing after coffee and cigarette smoke staining and to determine the enamel susceptibility to restaining. METHODS: The authors used a colorimeter to determine the baseline color of 40 bovine labial enamel surfaces according to the Commission Internationale de l'Eclairage L*a*b* coordinates. They immersed one-half of the specimens in coffee and exposed one-half to cigarette smoke in a smoking machine. They took color measurements again and determined the color change from baseline (ΔE1) for each group. The authors divided each group into two subgroups and subjected the specimens to at-home bleaching (one hour per day for 21 days) or simulated toothbrushing (120 cycles per day for 21 days), followed by another color measurement (ΔE2). The authors repeated both staining procedures (that is, cigarette smoke and coffee) and followed them with a third color measurement (ΔE3). They analyzed the data by using a two-way analysis of variance and the Tukey test (α = 5 percent). RESULTS: Both staining procedures resulted in similar values for ΔE1. The specimens stained with coffee and cigarette smoke exhibited a significant reduction in color change after bleaching (P < .05). However, toothbrushing resulted in a significantly reduced color change only for cigarette smoke-stained specimens (P < .001). The discoloration in coffee-stained specimens increased after restaining, irrespective of the stain removal method (P < .05). CONCLUSIONS: The study results show that at-home bleaching removed both coffee and cigarette smoke staining. The restaining potential was greater for specimens stained with coffee than for those stained with cigarette smoke, regardless of the removal method used. CLINICAL IMPLICATIONS: Six percent hydrogen peroxide at-home bleaching was effective in removing stains caused by coffee or cigarette smoke. However, continued frequent consumption of coffee can increase the staining susceptibility of enamel.

Effect of ceramic veneer opacity and exposure time on the polymerization efficiency of resin cements.

The objective of this study was to determine the degree of conversion (DC), hardness (H), and modulus of elasticity (E) of a dual-cured resin cement, a light-cured resin cement, and a flowable resin cured through opaque or translucent ceramic with different exposure times. RelyX ARC (dual), RelyX Veneer (light-cured), and Filtek Z350 Flow resin specimens 0.5 mm thick were cured for 40, 80, and 120 seconds through 1-mm thick translucent or opaque feldspathic ceramic disks (n=10). The specimens were stored at 37°C for 24 hours. Half of each specimen was used to test the DC and the other half to test H and E. The DC was determined in a Fourier transform infrared spectrometer in absorbance mode at peaks of 1638 cm(-1) and 1610 cm(-1). H and E were determined using nanoindentation with one loading cycle and a maximum load of 400 mN. The data were analyzed with three-way analysis of variance (ANOVA), the Games-Howell test, and the Pearson correlation test (α=0.05). Statistically significant differences were found for all three factors (material, opacity, and exposure time), as well as interaction between them. The opaque ceramic resulted in lower DC, H, and E than the translucent ceramic for an exposure time of 40 seconds. An exposure time of 120 seconds resulted in a similar DC for all materials, irrespective of the opacity of the ceramic. Materials cured for 120 seconds had higher H and E than those cured for 40 seconds. The exposure time and opacity of the ceramic exerted an influence on the DC, H, and E of the materials evaluated.