Effects of disinfection with a vinegar-hydrogen peroxide mixture on the surface characteristics of denture acrylic resins.

OBJECTIVE: This study aimed to investigate changes in the surface characteristics of two denture resins when disinfected with a vinegar-hydrogen peroxide (VHP) mixture. MATERIALS AND METHODS: Microwave-polymerized or 3D printed acrylic resin disks were immersed for 900 min (simulating 90 daily uses) in the following solutions (N = 10): water; 0.5% sodium hypochlorite; hydrogen peroxide and water dilution (1:1 ratio); vinegar and water dilution (1:1 ratio); and VHP mixture. Surface roughness, Knoop microhardness, surface free energy, and scanning electron microscopic images were assessed before and after the immersions. Results were compared using the 2-way ANOVA for repeated measures and Tukey test, at 5% significance. RESULTS: Surface roughness and microhardness did not differ (P > .05) among the solutions and times. Surface free energy and its dispersive component increased (P < .05) for all solutions. All solutions, except for water and VHP mixture, degraded microtopography. CONCLUSIONS: The VHP mixture was not deleterious to conventional and 3D-printed resin surfaces. CLINICAL RELEVANCE: Conventional and 3D printed resin dentures can be disinfected with a VHP mixture in a 1:1 ratio because this mixture does not substantially affect the surface characteristics after 90 daily immersions. On the contrary, sodium hypochlorite, hydrogen peroxide, and vinegar solutions, even in low concentrations, should be used with caution for denture disinfection because they may alter the resin microtopography over time.

Fit and fatigue behavior of CAD-CAM lithium disilicate crowns.

STATEMENT OF PROBLEM: New computer-aided design and computer-aided manufacturing (CAD-CAM) lithium disilicate glass-ceramics have been marketed. However, information concerning their biomechanical behavior is lacking. PURPOSE: The purpose of this in vitro study was to compare the fit and fatigue behavior of two recently introduced CAD-CAM lithium disilicate materials with the standard IPS e.max CAD ceramic and to investigate the effect of the thermal treatment for crystallization on crown fit. MATERIAL AND METHODS: Monolithic crowns (n=15) were milled from 3 CAD-CAM lithium disilicates: IPS e.max CAD (Ivoclar AG), Rosetta SM (Hass), and T-lithium (Shenzhen Upcera Dental Technology). Marginal and internal fit were evaluated using the replica technique before and after crystallization, and the fatigue behavior of the luted crowns was evaluated by the step-stress method. One-way ANOVA and the Tukey test were used to compare fit among the materials. Fatigue failure load was evaluated by the Kaplan-Meier and Mantel-Cox tests. The effect of crystallization on fit was evaluated with the paired t test (α=.05). RESULTS: Marginal fit was different between IPS e.max CAD (74 µm) and Rosetta SM (63 µm) (P=.02). T-lithium was similar to the other ceramics (68 µm) (P>.05). Occlusal internal space was similar among all materials (P=.69). Fatigue failure loads of Rosetta SM (1160 N) and T-lithium (1063 N) were similar to IPS e.max CAD (1082 N) (P>.05). The fatigue failure load of Rosetta SM was higher than that of T-lithium (P=.04). Crystallization reduced the axial internal space of all materials (P<.05) without significantly affecting marginal fit (P>.05). CONCLUSIONS: The fit and fatigue behavior of Rosetta SM and T-lithium were similar to that of IPS e.max CAD. Crystallization reduced the internal space of the crowns.

A qualitative analysis of denture wearing experience affecting the quality of life of older adults.

OBJECTIVE: To explore how denture-related experiences affect older adults' quality of life using a qualitative assessment of the Oral Health Impact Profile for Edentulous individuals (OHIP-Edent). MATERIALS AND METHODS: Twenty elderly individuals were interviewed before and 3 months after delivering new complete dentures, using an open-ended interview guide based on the OHIP-Edent. Interviews were audio-recorded and transcribed. Data were open coded and thematically analyzed following a Grounded Theory approach. Findings were integrated and constantly compared to understand the interviewees' difficulties, beliefs, and perceptions. RESULTS: Three interconnected themes were developed: functional and psychosocial impairments, and coping strategies. Even when posed as an open-ended format, the wording of some OHIP-Edent items was confusing while others were not relevant to the respondents. New categories related to speaking, smiling, swallowing, emotional and functional coping emerged from the interviews. Interviewees adapted to chewing and swallowing difficulties through food avoidance, modification of food choice and preparation techniques, and changes in dietary behaviors. CONCLUSIONS: Denture wearing is a daily challenging experience that encompasses various functional and psychosocial aspects and sheds light on the need for addressing the coping strategies employed by patients, as the current OHIP-Edent items may not fully represent other deemed important aspects of the quality of life of individuals who wear dentures. CLINICAL RELEVANCE: Dentists must not solely rely on structured questionnaires to explore the impact of denture wearing and treatment outcomes. Clinicians can use a more holistic approach to comprehend older adults' experiences with dentures including advice about coping mechanisms, food preparation techniques, and meal planning.

Effects of disinfection with a vinegar-hydrogen peroxide mixture on the surface composition and topography of a cobalt-chromium alloy.

STATEMENT OF PROBLEM: Choosing the best disinfection agent for removable partial dentures may be challenging since most commercially available disinfection solutions alter the properties of the metal framework. PURPOSE: The purpose of this in vitro study was to analyze the changes in the surface topography and elemental composition of a cobalt-chromium (Co-Cr) alloy when immersed in a vinegar-hydrogen peroxide mixture. MATERIAL AND METHODS: Disk-shaped specimens (N=50) were fabricated with Co-Cr alloy and randomly distributed into 5 groups (N=10) according to the immersion solutions: distilled water (control) (W); 0.5% sodium hypochlorite (H); 3% hydrogen peroxide and water in a 1:1 ratio (HP); vinegar and water in a 1:1 ratio (V); and vinegar and 3% hydrogen peroxide mixture in a 1:1 ratio (VHP). The immersions simulated 90 uses of 10 minutes each. The surface topography and the elemental composition were analyzed with scanning electron microscopy and energy-dispersive spectroscopy, before (T0) and after (T1) the immersions. The 2-way ANOVA for repeated measures was used for statistical comparisons (α=.05). RESULTS: The tested mixture (VHP) did not change the metal surface topography or increase the oxygen proportion, indicating that no corrosion occurred. Similarly, groups W, HP, and V had no topographic changes and nonsignificant statistical differences at T1 for elemental composition (P>.05). However, the specimens immersed in sodium hypochlorite (H) showed staining, surface irregularity, composition change, with an appearance of 22.56% more oxygen, 41% less chromium, and 28.77% less cobalt at T1 (P<.05). CONCLUSIONS: The immersion of Co-Cr alloy in a vinegar-hydrogen peroxide mixture did not change the surface structure of the metal.

Effect of a vinegar-hydrogen peroxide mixture on the surface properties of a cobalt-chromium alloy: A possible disinfectant for removable partial dentures.

STATEMENT OF PROBLEM: A vinegar-hydrogen peroxide mixture has been reported to be effective in eliminating Candida albicans and Staphylococcus aureus from acrylic resin, and its action has been reported to be comparable with that of sodium hypochlorite or peracetic acid. However, the effects of this mixture on cobalt-chromium alloys remain unknown. PURPOSE: The purpose of this in vitro study was to evaluate the surface roughness, Knoop microhardness, surface free energy, and wettability of a cobalt-chromium alloy when exposed to a vinegar-hydrogen peroxide mixture. MATERIAL AND METHODS: Fifty specimens of cobalt-chromium alloy were fabricated and immersed for 900 minutes, simulating 3 months of a daily 10-minute immersion in the following chemical agents (n=10): distilled water (W); 0.5% sodium hypochlorite (H); 3% hydrogen peroxide and water dilution in 1:1 ratio (HP); white-wine vinegar and water dilution in 1:1 ratio (V); and vinegar and hydrogen peroxide mixture in 1:1 ratio (VHP). Surface roughness, Knoop microhardness, surface free energy, and wettability were measured with single blinding before and after immersions. Data were statistically analyzed by using 2-way repeated measures ANOVA (α=.05). RESULTS: The vinegar-hydrogen peroxide mixture did not affect the surface roughness or Knoop microhardness. However, 0.5% sodium hypochlorite significantly increased the roughness and decreased microhardness. Surface free energy and wettability increased after immersions, regardless of the types of solution. CONCLUSIONS: Immersion in a vinegar-hydrogen peroxide mixture did not affect the surface characteristics of a cobalt-chromium alloy.

Keratinocyte Cytotoxicity of Peracetic Acid Used as Sterilizing Agent for Implant Scaffolds.

Peracetic acid (PAA) has been used to sterilize biomaterial scaffolds and allografts before their implantation. Although the antimicrobial effectiveness of PAA is widely known, there are no studies investigating its cytotoxicity on keratinocytes. This study aimed to investigate the cytotoxicity of PAA concentrations on keratinocytes by growing HaCaT cells in culture medium. Different concentrations of PAA (control-untreated, 0.01, 0.1, 1, 10, 100, 200, 400, 800, 1200, 1600, and 2000 ppm) were added to the culture wells and allowed to be in direct contact with cells for up to 24 hours. Cytotoxicity was quantitatively and qualitatively determined by cell viability assay and analysis of morphological changes. Statistical analysis was performed with 1-way analysis of variance and Tukey test at 5% significance. Cells treated with 0.01 and 0.1 ppm followed the same morphological pattern of untreated cells, whereas cells treated with 1.0 ppm presented about 20% of floating cells and dark cytoplasmic granules. More than 50% of the cells treated with 10 and 100 ppm were destroyed, whereas the attached ones showed unclear and interrupted cell membranes. Concentrations of 1 ppm or greater had less than 64.4% of viable cells compared with the control group. This study concluded that exposure of keratinocytes to concentrations of 1 ppm or greater of PAA resulted in strong cytotoxic effects.

Antimicrobial effect and cytotoxic activity of vinegar-hydrogen peroxide mixture: A possible alternative for denture disinfection.

STATEMENT OF PROBLEM: Soaking dentures in vinegar or hydrogen peroxide does not seem to remove the microorganisms involved with prosthetic stomatitis efficiently. A mixture of these 2 substances may be effective, but studies are lacking. PURPOSE: The purpose of this in vitro study was to evaluate the antimicrobial effect and cytotoxic activity of vinegar-hydrogen peroxide mixtures against Candida albicans and Staphylococcus aureus. MATERIAL AND METHODS: For antimicrobial tests, planktonic cells and biofilms of C. albicans and S. aureus cultured on acrylic resin disks were exposed to 0.5% sodium hypochlorite; 0.2% peracetic acid; vinegar-hydrogen peroxide mixtures at concentration ratios 1:1, 1:3, and 3:1; vinegar-water mixtures at concentration ratios 1:1, 1:3, and 3:1; and hydrogen peroxide-water mixtures at concentration ratios 1:1, 1:3, and 3:1. Antimicrobial activity was evaluated by counting viable colony-forming units after disinfection. For cytotoxicity tests, the 1:1 vinegar-hydrogen peroxide mixture was serially diluted (10-1 to 10-4) and allowed to be in direct contact with HaCaT keratinocytes for 24 hours. Cytotoxicity was quantitatively and qualitatively determined by counting the number of viable cells and analyzing morphological cell changes. RESULTS: All vinegar-hydrogen peroxide mixtures, sodium hypochlorite, and peracetic acid efficiently eliminated C. albicans and S. aureus (P<.05), whereas vinegar and hydrogen peroxide solutions used separately were not as efficient as the experimental mixtures. The 10-3 and 10-4 dilutions of vinegar-hydrogen peroxide solutions were considered noncytotoxic, whereas dilutions below 10-2 were strongly cytotoxic, comparable with the 10-2 dilution of 0.2% peracetic acid. CONCLUSIONS: The vinegar-hydrogen peroxide mixture effectively eliminated C. albicans and S. aureus from acrylic resin. Dilutions equal or below 10-2 of this mixture presented strong cytotoxic effects.

A Randomized Controlled Trial of Mastication with Complete Dentures Made by a Conventional or an Abbreviated Technique.

PURPOSE: The aim of this randomized clinical trial was to test the hypothesis that there are no statistically significant differences after 3 and 6 months in masticatory performance or chewing ability of people with new complete dentures made by an abbreviated or a conventional technique. MATERIALS AND METHODS: The trial included 20 edentulous participants at a dental school in Brazil assigned randomly to receive dentures made by either a conventional technique involving six clinical sessions or by an abbreviated technique involving three clinical sessions. At baseline with old dentures and at 3 and 6 months with new dentures, masticatory performance was measured by counting the number of chewing strokes and the time before participants had an urge to swallow and by calculating the medium particle size of a silicone material after 20 chewing strokes and at the urge to swallow. On each occasion, the participants recorded on visual analog scales their ability to chew five food textures. Statistical significance (P ≤ .05) of changes in masticatory performance and chewing ability during the trial were analyzed with generalized estimating equations. RESULTS: Both techniques improved masticatory performance between baseline and 6 months and the ability to bite and chew all foods apart from hard apples. CONCLUSION: There were no significant differences in masticatory performance or chewing ability after 6 months between complete dentures made by a conventional or an abbreviated technique.

Sleep bruxism: challenges and restorative solutions.

Bruxism is a parafunctional activity related to clenching or grinding the teeth and tooth wear can be a consequence of sleep bruxism (SB). Management of severe tooth wear due to SB is a challenging situation because of the common reduced amount of remaining dental structure and loss of vertical dimension of occlusion. Rationale for the planning of oral rehabilitation of patients with SB presenting severe tooth wear should rely on evidence-based approaches; however, few studies have discussed properties of dental materials for SB rehabilitation and how to cosmetically manage severe tooth wear. This review aimed to provide an overview into bruxism cosmetic rehabilitation and how this can be implemented with good outcomes for the patient.

Partial denture metal framework may harbor potentially pathogenic bacteria.

PURPOSE: The aim of this study was to characterize and compare bacterial diversity on the removable partial denture (RPD) framework over time. MATERIALS AND METHODS: This descriptive pilot study included five women who were rehabilitated with free-end mandibular RPD. The biofilm on T-bar clasps were collected 1 week (t1) and 4 months (t2) after the RPD was inserted (t0). Bacterial 16S rDNA was extracted and PCR amplified. Amplicons were cloned; clones were submitted to cycle sequencing, and sequences were compared with GenBank (98% similarity). RESULTS: A total of 180 sequences with more than 499 bp were obtained. Two phylogenetic trees with 84 (t1) and 96 (t2) clones represented the bacteria biofilm at the RPD. About 93% of the obtained phylotypes fell into 25 known species for t1 and 17 for t2, which were grouped in 5 phyla: Firmicutes (t1=82%; t2=60%), Actinobacteria (t1=5%; t2=10%), Bacteroidetes (t1=2%; t2=6%), Proteobacteria (t1=10%; t2=15%) and Fusobacteria (t1=1%; t2=8%). The libraries also include 3 novel phylotypes for t1 and 11 for t2. Library t2 differs from t1 (P=.004); t1 is a subset of the t2 (P=.052). Periodontal pathogens, such as F. nucleatum, were more prevalent in t2. CONCLUSION: The biofilm composition of the RPD metal clasps changed along time after RPD wearing. The RPD framework may act as a reservoir for potentially pathogenic bacteria and the RPD wearers may benefit from regular follow-up visits and strategies on prosthesis-related oral health instructions.

Evaluation of tensile strength resistance of different biomaterials in calvarial rats

AIM: The aim of this study was to determine the effect of different grafting materials on bone tensile strength after 6-month wound healing. MATERIAL AND METHODS: Non-critical size defects (3-mm diameter) were created in calvarium of 30 three-month-old Wistar rats. Animals were divided into 3 groups (n=10) treated with different grafting materials: GenOx® (Group 1A); GenMix® (Group 1B); no treatment (blood clot, Group 3). Six months after the surgery, rats were sacrificed; bone specimens were harvested and submitted to tensile strength test using a universal testing machine. The bone fracture surface morphology was evaluated using scanning electron microscopy (SEM) at 200X magnification. Data were compared by One-Way ANOVA at 5% significance. RESULTS: No significant difference was found among the groups although tensile strength decreased in the following order: Group 3 (9.56±3.74MPa), Group 1B (8.58±3.60MPa), Group 1A (7.70±2.41MPa). All tested materials showed similar effects on bone tensile strength, no matter the source (xenogenic or blood clot). CONCLUSION: After six months of bone healing, the type of grafting material is irrelevant to the final outcome and bone tensile strength.

Association between sleep bruxism and gastroesophageal reflux disease.

STATEMENT OF PROBLEM: Rhythmic masticatory muscle activity, including sleep bruxism (SB), can be induced in healthy individuals by experimental esophageal acidification, which plays an important role in the pathogenesis of gastroesophageal reflux disease (GERD). However, no robust evidence supports the association between SB and GERD. PURPOSE: The purpose of this study was to investigate the association between SB and GERD. MATERIAL AND METHODS: Forty-five individuals were eligible to participate in this observational transversal study at the Gastroenterology Service of the Clinical Hospital of Porto Alegre, Brazil. The participants were classified into 2 groups, those with and without GERD, according to the Montreal Criteria and pH-metry/endoscopy findings. The diagnosis of SB was not assessed in a sleep laboratory but was based on self-report plus clinical inspection, according to the minimal diagnostic criteria of the American Academy of Sleep Medicine. The Lipp Stress Symptom Inventory was used to evaluate self-perceived stress. Univariate and multiple logistic regression analyses were performed with SB as dependent variable and GERD, sex, age, body mass index, and stress as predictors (α=.05; 90% power). RESULTS: The study population included individuals with SB without GERD (13.3%) and individuals with SB with GERD (31.1%). In participants with GERD, the prevalence of SB was 73.7%. Only the variable GERD was significantly associated with SB (P=.017; odds ratio 6.58; 95% confidence interval 1.40-30.98), although adjusted for stress and age. CONCLUSIONS: Sleep bruxism is prevalent in GERD patients, and GERD is highly associated with SB.

Circadian rhythm and cartilage extracellular matrix genes in osseointegration: a genome-wide screening of implant failure by vitamin D deficiency.

BACKGROUND: Successful dental and orthopedic implants require the establishment of an intimate association with bone tissue; however, the mechanistic explanation of how biological systems accomplish osseointegration is still incomplete. We sought to identify critical gene networks involved in osseointegration by exploring the implant failure model under vitamin D deficiency. METHODOLOGY: Adult male Sprague-Dawley rats were exposed to control or vitamin D-deficient diet prior to the osteotomy surgery in the femur bone and the placement of T-shaped Ti4Al6V implant. Two weeks after the osteotomy and implant placement, tissue formed at the osteotomy site or in the hollow chamber of T-shaped implant was harvested and total RNA was evaluated by whole genome microarray analyses. PRINCIPAL FINDINGS: Two-way ANOVA of microarray data identified 103 genes that were significantly (>2 fold) modulated by the implant placement and vitamin D deficiency. Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses assigned the highest z-score to the circadian rhythm pathway including neuronal PAS domain 2 (NPAS2), and period homolog 2 (Per2). NPAS2 and Aryl hydrocarbon receptor nuclear translocator-like (ARNTL/Bmal 1) were upregulated around implant and diminished by vitamin D deficiency, whereas the expression pattern of Per2 was complementary. Hierarchical cluster analysis further revealed that NPAS2 was in a group predominantly composed of cartilage extracellular matrix (ECM) genes. Whereas the expression of bone ECM genes around implant was not significantly affected by vitamin D deficiency, cartilage ECM genes were modulated by the presence of the implant and vitamin D status. In a proof-of-concept in vitro study, the expression of cartilage type II and X collagens was found upregulated when mouse mesenchymal stem cells were cultured on implant disk with 1,25D supplementation. CONCLUSIONS: This study suggests that the circadian rhythm system and cartilage extracellular matrix may be involved in the establishment of osseointegration under vitamin D regulation.