Cytotoxicity evaluation, antibacterial effect, and degree of conversion of QAM-containing adhesives.

The aim of this study was to evaluate the influence of adding quaternary ammonium methacrylates (QAMs) to experimental adhesives by assessing the degree of conversion (DC), cytotoxicity against keratinocytes and fibroblasts, and antibacterial activity against biofilm formation. Two QAMs were added to an experimental adhesive: dimethylaminododecyl methacrylate bromododecane (DMADDM) or dimethylaminododecyl methacrylate bromohexadecane (DMAHDM) at three concentrations each: 1, 2.5, and 5 wt.%. Experimental adhesive without QAMs (control group) and commercially available Transbond XT Primer (3M Unitek, Monrovia, California, USA) were used for comparisons. The adhesives were tested for DC, cytotoxicity against keratinocytes and fibroblasts, and antibacterial activity against biofilm formation. DC, cytotoxicity against fibroblasts, and antibacterial activity were analyzed using one-way ANOVA and Tukey's multiple comparisons. Cytotoxicity against keratinocytes was evaluated using the Kruskal Wallis and Dunn's post-hoc (α = 5%) tests. Transbond showed lower DC as compared to 5% DMAHDM, 1% DMADDM, and 5% DMADDM (p < 0.05). However, all groups presented proper DC when compared to commercial adhesives in the literature. In the evaluation of cytotoxicity against keratinocytes, Transbond induced higher viability than 2.5 wt.% groups (p < 0.05). Against fibroblasts, Transbond induced higher viability as compared to 5 wt.% groups (p < 0.05). DMAHDM at 5 wt.% reduced biofilm formation when compared to all the other groups (p < 0.05). Despite their cytotoxic effect against keratinocytes, gingival fibroblasts showed higher viability. DMAHDM at 5 wt.% decreased Streptococcus mutans viability. The incorporation of DMAHDM at 5 wt.% may be a strategy for reducing the development of white spot lesions.

Influence of a gray background and the illuminant on tooth shade selection.

STATEMENT OF PROBLEM: Visual shade selection in dentistry may be influenced by factors that include the background color and the illuminant. PURPOSE: The purpose of this clinical study was to evaluate the influence of using a gray background and a light-correcting device on visual shade selection. MATERIAL AND METHODS: Two experienced clinicians assessed the incisor color of 30 volunteers using the VITA 3D-MASTER shade guide. Visual analyses were carried out using or not (control) a gray background, with and without (control) a light-correcting device (Smile Lite). Furthermore, the use of a polarizing filter was evaluated. Data from a clinical spectrophotometer were defined as the standard instrumental analysis. The agreement and the similarity (based on the whitening indexes of tabs) were evaluated between instrumental and visual analyses. Statistical testing was conducted through ordinal logistic regression and repeated-measures ANOVA. The Shapiro-Wilk test was used to confirm the data distribution, and homogeneity of variance was assessed with the Levene test (α=.05) RESULTS: The use of Smile Lite resulted in lighter tabs than indicated by the instrumental analysis, and the opposite was observed in its absence. The polarizing filter did not affect the results (P>.05). For similarity, the illuminant improved the results (P<.001). The gray background reduced the differences between visual and instrumental analysis only in the absence of the Smile Lite (P<.001). CONCLUSIONS: The color similarity between visual and instrumental analysis improved with the use of a light-correcting device with or without a polarization filter. A gray background was useful only without the light-correcting device.

Effect of gingival barrier brands on operator perception, cervical adaptation, and patient comfort during in-office tooth bleaching: a randomized clinical trial.

BACKGROUND: Light-cured resins are widely used as gingival barriers to protect the gums from highly concentrated peroxides used in tooth bleaching. The impact of barrier brand on clinical outcomes is typically considered negligible. However, there is limited evidence on the effects of different brands on operator experience, barrier adaptation, and patient comfort. OBJECTIVE: This clinical trial assessed the impact of four commercial gingival barrier brands (Opaldam, Topdam, Lysadam, and Maxdam) on operator perception, adaptation quality, and patient comfort. METHODS: Twenty-one undergraduate students placed gingival barriers in a randomized sequence using blinded syringes. Photographs of the barriers were taken from frontal and incisal perspectives. After bleaching procedures, operators rated handling features and safety using Likert scale forms. Two experienced evaluators independently assessed barrier adaptation quality on a scale from 1 (perfect) to 5 (unacceptable). The absolute risk of barrier-induced discomfort was recorded. Data were analyzed using Friedman and Chi-square tests (α = 0.05). RESULTS: Opaldam and Topdam received the highest scores in most handling features, except for removal, which was similar among all brands. No significant difference was observed in barrier adaptation quality between the evaluated brands. Discomforts were mainly reported in the upper dental arch, with Maxdam having the highest absolute risk (35% for this arch and 24% overall). CONCLUSIONS: This study suggests that gingival barrier brands can influence operator perception and patient comfort. Opaldam and Topdam were preferred by operators, but all brands demonstrated comparable adaptation quality. CLINICAL TRIAL REGISTRATION: The study was nested in a randomized clinical trial registered in the Brazilian Clinical Trials Registry under identification number RBR-9gtr9sc.

Cytotoxicity evaluation, antibacterial effect, and degree of conversion of QAM-containing adhesives

Abstract The aim of this study was to evaluate the influence of adding quaternary ammonium methacrylates (QAMs) to experimental adhesives by assessing the degree of conversion (DC), cytotoxicity against keratinocytes and fibroblasts, and antibacterial activity against biofilm formation. Two QAMs were added to an experimental adhesive: dimethylaminododecyl methacrylate bromododecane (DMADDM) or dimethylaminododecyl methacrylate bromohexadecane (DMAHDM) at three concentrations each: 1, 2.5, and 5 wt.%. Experimental adhesive without QAMs (control group) and commercially available Transbond XT Primer (3M Unitek, Monrovia, California, USA) were used for comparisons. The adhesives were tested for DC, cytotoxicity against keratinocytes and fibroblasts, and antibacterial activity against biofilm formation. DC, cytotoxicity against fibroblasts, and antibacterial activity were analyzed using one-way ANOVA and Tukey's multiple comparisons. Cytotoxicity against keratinocytes was evaluated using the Kruskal Wallis and Dunn's post-hoc (α = 5%) tests. Transbond showed lower DC as compared to 5% DMAHDM, 1% DMADDM, and 5% DMADDM (p < 0.05). However, all groups presented proper DC when compared to commercial adhesives in the literature. In the evaluation of cytotoxicity against keratinocytes, Transbond induced higher viability than 2.5 wt.% groups (p < 0.05). Against fibroblasts, Transbond induced higher viability as compared to 5 wt.% groups (p < 0.05). DMAHDM at 5 wt.% reduced biofilm formation when compared to all the other groups (p < 0.05). Despite their cytotoxic effect against keratinocytes, gingival fibroblasts showed higher viability. DMAHDM at 5 wt.% decreased Streptococcus mutans viability. The incorporation of DMAHDM at 5 wt.% may be a strategy for reducing the development of white spot lesions.

Luting laminate veneers: Do resin-composites produce less polymerization stress than resin cements?

OBJECTIVES: Regular composites could produce less polymerization stress than resin cements when luting laminate veneers but there is no proper evidence to support this theory. The current study aimed to determine the degree of conversion, volumetric shrinkage, polymerization stress and the resultant elastic moduli of materials currently used for adhesive cementation and to determine possible correlations. METHODS: The study considered (i) regular resin composites (Admira Fusion, Gradia, Grandioso, Palfique, Sirius Z, Viscalor and Z100) at room and pre-warmed (PW) at 69ºC, (ii) flowable composites (Sigma Flow and Grandioso Flow); (iii) solely light-activated cements (AllCem Veneer, Variolink Esthetic and RelyX Veneer); and (iv) one dual-activated resin cement (SpeedCEM). Degree of conversion (DC, n = 3) was accessed with FTIR 1 h after irradiation. Bonded-disk and Bioman II instruments were used to access polymerization shrinkage strain and shrinkage stress, respectively, for 60 min at 23 ± 1◦C (n = 3). The elastic modulus was determined by 3-point bending flexural test (n = 6). The results were submitted to analyse s of variance, Tukey's, and correlation tests. RESULTS: For regular composites, the pre-warming did not affect DC, shrinkage and modulus but significantly increased the stress magnitude. Correlation tests indicated a significant relationship only between stress and polymerization shrinkage (r = 0.811343). SIGNIFICANCE: Regular composites can produce less polymerization stress than resin cements when luting laminate veneers. Polymerization stress was dependent on the shrinkage magnitude, but not on the degree of conversion nor the elastic modulus.

Effectiveness of Supportive Care in the Prevention of Peri-implant Diseases in Brånemark Protocol Rehabilitations: A Retrospective Cohort Study.

This retrospective cohort study aimed to evaluate the efficiency of supportive periodontal treatment (SPT) on peri-implant disease prevention. A total of 63 rehabilitated patients with 504 implants were selected with both maxillary and mandibular Brånemark-type protocols (all-on-four system) placed between 2004 and 2014 in a private practice with 5 to 15 years of follow-up. Study participants were divided into those who adhered to SPT with regular intervals of two or more times a year (Group 1) and those with irregular intervals with more than 1 year without attending SPT (Group 2). The implants placed were evaluated clinically and radiographically to assess peri-implant diseases. The prevalence of mucositis and peri-implantitis in the total population was 64.7% (326 implants) and 3.7% (19 implants), respectively. Group 2 had higher rates of mucositis (181 implants) and peri-implantitis (16 implants) than Group 1 (145 and 3 implants, respectively) (P < .05). The odds ratio for peri-implantitis in Group 2 was 7.1. The results suggest that patients who regularly received SPT had lower chances of developing peri-implant diseases.

Aplicações da dentina autógena na regeneração óssea: revisão integrativa de literatura / Applications of dentine in bone regeneration: integrative literature review

A dentina e o osso alveolar apresentam muita semelhança em sua composição. Sendo assim, podemos considerar a utilização da dentina como recurso alternativo nas intervenções que buscam a regeneração tecidual óssea. Objetivo: o presente estudo realizou uma revisão integrativa da literatura sobre o uso da dentina como biomaterial para regeneração óssea. Metodologia: foi realizada uma busca por artigos, nas bases de dados Medline, via PubMed; Scielo, LILACS, BASE, Scopus e Science Direct, queavaliassem ou descrevessem o uso da dentina como biomaterial para regeneração óssea. Foram utilizados os seguintes descritores: "Dentin" AND "Bone Regeneration", sem delimitação de tempo. Os critérios de inclusão foram: estudos clínicos publicados em periódicos, oriundos de dados primários, sobre o uso de dentina como biomaterial. Os critérios de exclusão foram: revisões de literatura, estudos in vitro e em animais, estudos que não fosse possível o acesso na íntegra e estudos que associassem o uso da dentina com outros biomateriais sem que fosse possível relacionar os resultados apenas pelo uso da dentina. Resultados: vinte e três estudos foram selecionados para a presente revisão. As pesquisas demonstraram que há uma heterogenicidade relacionada ao tamanho da partícula de dentina obtida, que pode ser decorrente de diferentes métodos de processamento. Conclusão: a reutilização da dentina como biomaterial pode ser uma alternativa promissora ao enxerto autógeno. Sugere-se, então, que protocolos de processamento da partícula de dentina sejam melhor estabelecidos e estudos longitudinais precisam ser realizados para a garantia de procedimentos seguros, eficazes e práticos.

The dentin and the alveolar bone are very similar in composition, therefore, it's usage as an alternative resource in interventions that seek tissue regeneration can be considered. Objective: the aim of the present study was to carry out an integrative review of the literature on the use of dentin as a biomaterial for bone regeneration. Methodology: a search for articles was carried out in the Medline databases, via PubMed; Scielo, LILACS, BASE, Scopus and Science Direct, which evaluated or described the use of dentin as a biomaterial for bone regeneration. The following descriptors were used: "Dentin" AND "Bone Regeneration", without time limits. The inclusion criteria were: clinical studies published in journals, derived from primary data, on the use of dentin as a biomaterial. Exclusion criteria were: literature reviews, in vitro and in animal studies, studies that were not possible to be accessed in full and studies that associated the usage of dentin with other biomaterials and that it was not possible to relate the results just by using the dentin. Results: twenty-three studies were selected for the present review. Researches have shown that there is heterogeneity related to the size of the obtained dentin particle, which may be due to different processing methods. Conclusion: the reuse of dentin as a biomaterial can be a promising alternative to autogenous graft. It is suggested, then, that dentin particle processing protocols should are better established and longitudinal studies need to be carried out to the in order to ensure safe, effective and practical procedures.

Alternative treatment to orthognatic surgery by the application of digital smile planning.

Through the use of the application of a mathematical proportion and a digital golden ratio compass associated with computer software, Digital Smile Planning (DSP) can assist clinicians to achieve the fundamentals of esthetic treatment. The present clinical report describes the application of this technique to propose an alternative and more conservative treatment for a patient who refused the option of orthognathic surgery. To address the diagnosis of a gingival smile with vertical maxillary excess, the alternative treatment comprised crown lengthening surgery, ceramic veneers on the maxillary teeth, and the application of botulinum toxin to reduce lip hyperactivity. Considering the successful resolution of the patient's situation from the perspective of both the dentist and the patient, the application of DSP was considered to be useful to achieve predictable harmony between the face and the dental structures.

Can bulk-fill compromise the curing potential in deep cavities? / Bulkfill pode comprometer o potencial de polimerização em cavidades profundas?

Objective: To determine the effect of the restorative technique, material's opacity and the selected light sources on the curing potential (CP) in deep cavities. Material and Methods: The radiant exitance (mW/cm2) of two light curing units (Bluephase G2 and Radii-Cal) was determined at 0 and 8 mm distance from a power meter sensor (Ophir). Two bulk-fill composites of regular consistency (Opus, FGM; and Filtek One, 3M) and a conventional one (Sirius-Z, DFL) were considered and the level of their opacity were determined by a sphere-based spectrophotometer (SP60, X-Rite). The degree of C=C conversion (DC) was determined by spectroscopy (FTIR-ATR) at 0.05 and 8 mm depths and the CP considered the ratio between them. The "incremental technique" considered 4 increments of 2mm thickness each, whereas the "bulk-fill technique considered 2 increments of 4mm-thickness. Data were submitted to analysis of variance and Tukey's test (95%). Pearson's correlation tests were performed to calculate the possible relation between curing potential and materials' opacity. Results: With the incremental technique it was possible to achieve high CP regardless of the light source. The CP of bulk-fill composites was dependent on the light source, whereas Radii-Cal compromised the DC at 8 mm for both materials. The correlation between opacity and CP was dependent on the light source (r = 0.891707246 for Radii-Cal; r = 0.515703768 for Bluephase G2). Conclusion: The bulk-fill technique was dependent on the light source while the incremental was not. The influence of materials' opacity was dependent on the light curing unit.(AU)

Objetivo: Determinar o efeito da técnica restauradora, a opacidade do material e as fontes de luz selecionadas sobre o potencial de cura (PC) em cavidades profundas. Materiais e métodos: A saída radiante (mW/cm2) de duas unidades de cura por luz (Bluephase G2 e Radii-Cal) foi determinada a 0 e 8 mm de distância de um sensor de potência (Ophir). Dois compósistos bulkfill de consistência regular (Opus, FGM; e Filtek One, 3M) e um convencional (Sirius-Z, DFL) foram considerados e o nível de sua opacidade foi determinado por um espectrofotômetro (SP60, X-Rite). O grau de conversão C=C (DC) foi determinado por espectroscopia (FTIR-ATR) a 0,05 e 8 mm de profundidade e o PC considerou a relação entre eles. A técnica incremental considerou 4 incrementos de 2 mm de espessura cada, enquanto que a técnica bulkfill considerou 2 incrementos de 4 mm de espessura. Os dados foram submetidos à análise de variância e ao teste de Tukey (95%). Os testes de correlação de Pearson foram realizados para calcular a possível relação entre o potencial de cura e a opacidade dos materiais. Resultados: Com a técnica incremental foi possível obter um PC elevado, independentemente da fonte de luz. O PC de compósitos bulkfill foi dependente da fonte de luz, enquanto que Radii-Cal comprometeu o DC em 8 mm para ambos os materiais. A correlação entre opacidade e PC foi dependente da fonte de luz (r = 0,891707246 para Radii-Cal; r = 0,515703768 para Bluephase G2). Conclusão: O potencial de polimerização para a técnica bulkfill foi dependente da fonte de luz, enquanto para a técnica incremental não. A influência da opacidade dos materiais sobre a capacidade de polimerização foi dependente da unidade de fotoativação. (AU)

Color change, tooth sensitivity, aesthetic self-perceptions and quality of life after at-home dental bleaching / Mudança de cor, sensibilidade dental, autopercepção estética e qualidade de vida após clareamento dental caseiro

Objective: The aim of this study was to determine the color change, tooth sensitivity, aesthetic self-perception and quality of life after at-home dental bleaching. Material and Methods: Dental examination was performed and the initial color of the upper right incisor was recorded using a spectrophotometer (Easyshade Compact, Vita Zahnfabrik) and CIELab parameters. Individual vinyl trays were delivered to the patients (n=37) who were instructed to use the carbamide peroxide 16% (Total Blanc Home C16%, DFL) for 2 hours daily for 2 weeks. One-week after the end of treatment, measurements were repeated to calculate color (ΔEab,ΔE00) and whiteness index (ΔWID) variations. Oral Health Impact Profile (OHIP) and Psychosocial Impact of Dental Aesthetics Questionnaire (PIDAQ) questionnaires were applied before and 30 days after treatment. Tooth sensitivity was by checked by visual analogue scale (VAS). Spearnan's correlation tests were used to verify the possible relation between color change parameters and sensitivity. The Wilcoxon test was applied for results obtained by OHIP and PIDAQ questionnaires. Results: Significant color change was observed after 14 days, regardless of the considered parameter. There was no significant correlation between sensitivity and color change. The dental self-confidence domain increased after bleaching (p = 0.029) and the psychological impact decreased (p = 0.001). Conclusion:At-home dental bleaching was effective on the overall whitening and the color change was not related to tooth sensitivity. The bleaching treatment had a positive impact on the quality of life, reducing psychological discomfort and improving dental self-confidence and aesthetic self-perception. (AU)

Objetivo: O objetivo deste estudo foi determinar a mudança de cor, sensibilidade dental, autopercepção estética e qualidade de vida após clareamento dental caseiro. Material e Métodos: Uma consulta inicial foi realizada e a cor inicial do incisivo superior direito foi registrada usando um espectrofotômetro (Easyshade Compact, Vita Zahnfabrik) e parâmetros CIELab. Moldeiras individuais confeccionadas em vinil foram entregues aos pacientes participantes (n = 37), que foram instruídos a usar o gel à base de peróxido de carbamida 16% (Total Blanc Home C16%, DFL) durante 2 horas diárias durante 2 semanas. Uma semana após o término do tratamento, as medidas foram repetidas para calcular a variação de cor (ΔEab, ΔE00) e o índice de brancura (ΔWID). Os questionários OHIP (Oral Health Impact Profile) e PIDAQ (Psychosocial Impact of Dental Aesthetics Questionnaire) foram aplicados antes e 30 dias após o tratamento. A sensibilidade dental foi verificada por meio da escala visual análoga (VAS). Os testes de correlação de Spearnan foram utilizados para verificar a possível relação entre os parâmetros de mudança de cor e sensibilidade. O teste Wilcoxon foi aplicado para os resultados obtidos pelos questionários OHIP e PIDAQ. Resultados: Mudança de cor significativa foi observada após 14 dias, independentemente do parâmetro considerado. Não houve correlação significativa entre a sensibilidade e a mudança de cor. O domínio da autoconfiança dental aumentou após o branqueamento (p = 0,029) e o impacto psicológico diminuiu (p = 0,001). Conclusão: O clareamento dental caseiro foi eficaz no branqueamento geral e a mudança de cor não estava relacionada à sensibilidade dental. O tratamento clareador teve um impacto positivo na qualidade de vida, reduzindo o desconforto psicológico e melhorando a autoconfiança dental e a autopercepção estética.(AU)

Light and viscosity effects on the curing potential of bulk-fill composites placed in deep cavities.

To determine the influence of light curing units (LCUs) and material viscosity on the degree of conversion (DC) of bulk-fill (BF) resin-based composites (RBCs) placed in deep cavity preparations. Four LCUs were tested: Valo cordless, Bluephase-G2, Poly wireless and Radii-cal. Light irradiance was determined at 0 mm and 6 mm distance to the reading sensor. The following RBCs were considered: Filtek BF, Filtek BF Flow, Opus BF, Opus BF Flow, Tetric N-Ceram BF and Surefil SDR Flow. Sirius-Z was used with the incremental technique. DC (n = 3) was evaluated by spectroscopy both at top and bottom regions of deep preparations with 6 mm depth. The data were submitted to ANOVA and Tukey's test (α = 0.05). Pearson's correlation (95%) was used to verify the relation between the LCUs and the curing potential of RBCs. The DC at 6 mm depth was reduced when Opus BF, Opus BF Flow and Tetric N-Ceram BF were activated with Radii-cal. There was a positive correlation between the LCU irradiance and the bottom/top conversion ratios. The materials' viscosities did not affect the curing potential. Bulk-fill composites did not present higher curing potential than the conventional composite used with the incremental technique; the most important aspect of the LCU was the irradiance ratio; and the materials' viscosity did not affect the curing potential as a function of depth. Radii-cal negatively impacted the degree of conversion at 6 mm depth for most bulk-fill resin composites. Depending on the brand, bulk-fill composites may present reduced curing potential due to the light source when placed in deep cavities. Dentists should avoid LCU with acrylic tips to photoactivate bulk-fill resin-based composites.

Physicochemical properties and biological effects of quaternary ammonium methacrylates in an experimental adhesive resin for bonding orthodontic brackets.

METHODOLOGY: Fixed orthodontic appliances may lead to biofilm accumulation around them that may increase caries risk. This study aimed to evaluate the influence of quaternary ammonium methacrylates (QAMs) on the physicochemical properties, cytotoxicity, and antibacterial activity of adhesive resins for orthodontic purposes. A base resin was prepared with a comonomer blend and photoinitiator/co-initiator system. Two different QAMs were added to the base adhesive: dimethylaminododecyl methacrylate at 5 wt.% (DMADDM) or dimethylaminohexadecyl methacrylate (DMAHDM) at 10 wt.%. The base adhesive, without QAMs, (GC) and the commercial Transbond™ XT Primer 3M (GT) were used as control. The resins were tested immediately and after six months of aging in the water regarding the antibacterial activity and shear bond strength (SBS). The antibacterial activity was tested against Streptococcus mutans via metabolic activity assay (MTT test). The groups were also tested for the degree of conversion (DC) and cytotoxicity against keratinocytes. RESULTS: The resins containing QAM showed antibacterial activity compared to the commercial material by immediately reducing the metabolic activity by about 60%. However, the antibacterial activity decreased after aging (p<0.05). None of the groups presented any differences for SBS (p>0.05) and DC (p>0.05). The incorporation of DMADDM and DMAHDM significantly reduced the keratinocyte viability compared to the GT and GC groups (p<0.05). CONCLUSION: Both adhesives with QAMs showed a significant reduction in bacterial metabolic activity, but this effect decreased after water aging. Lower cell viability was observed for the group with the longer alkyl chain-QAM, without significant differences for the bonding ability and degree of conversion. The addition of QAMs in adhesives may affect the keratinocytes viability, and the aging effects maybe decrease the bacterial activity of QAM-doped materials.

Influence of resin matrix on the rheology, translucency, and curing potential of experimental flowable composites for bulk-fill applications.

OBJECTIVE: To propose monomer formulations that show an optimal degree of conversion as a function of depth for bulk-fill applications. METHODS: Four resin blends were formulated with methacrylate-based monomers: BisGMA + TEGDMA (control); BisEMA + BisGMA + TEGDMA (BisEMA-based); UDMA + BisGMA + TEGDMA (UDMA-based) and BisEMA + UDMA + BisGMA + TEGDMA (BisEMA + UDMA-based). For each material, a photoinitiating system and silanized filler particles were added. The rheological analyses were performed with a rotational rheometer using the cone/plate geometry. CIELab coordinates were assessed over black and white backgrounds using a bench spectrophotometer (SP60, X-Rite) to calculate the translucency parameter (TP) for samples with 0.5, 4, and 6 mm thickness. The degree of CC conversion (DC) was determined by infrared spectroscopy (FTIR/ATR) at 0.05 mm (top), 4, and 6 mm depths (bottom), and the bottom-to-top ratio was considered. A broad spectrum-based LED was used for light activation. Analysis of variance and Tukey's test (95%) were performed on the results. RESULTS: The materials tested showed pseudoplastic and thixotropic behavior and a predominance of viscous effects over elastics. The control resin yielded the lowest viscosity for the entire shear rate investigated, followed by the BisEMA-based, BisEMA + UDMA-based, and UDMA-based group, which had the highest viscosity. The UDMA-based material showed the lowest TP as a function of thickness. Both the materials' formulations and depths significantly influenced the DC. The UDMA-based group promoted the highest DC ​​on the top (71 ± 1%) and 4 mm depth (68 ± 1%) but exhibited lower bottom-to-top DC ratio. The BisEMA + UDMA-based material promoted the highest bottom-to-top DC ratio at 4 mm (99%) and 6 mm (97%). SIGNIFICANCE: The resin matrix interferes in the rheological behavior, translucency parameter, and polymerization capacity as a function of depth. The material formulated with the addition of UDMA and BisEMA demonstrated the highest curing potential as a function of depth and can be useful for bulk-fill applications.

Adhesion and optics: The challenges of esthetic oral rehabilitation on varied substrates-Reflections based on a clinical report.

Patients with challenging prosthodontic conditions require rehabilitation with a biological, functional, and esthetic approach. When one or more teeth are badly discolored, their restoration is problematic because poor appearance affects not only the crown but also the periodontal tissues. This clinical report describes a complex esthetic rehabilitation with conservative tissue management and ceramic restorations. Subepithelial connective tissue graft surgery and the replacement of a cast metal post with a glass fiber post addressed the problem of a discolored maxillary central incisor. The discolored right maxillary incisor was restored with a combination of a medium-opaque, lithium-disilicate ceramic coping to mask the dark root and to approximate the color of the other incisors. Subsequently, 6 ceramic veneers were placed. A knowledge of the materials' optical properties and adhesion possibilities helped solve this complex problem.

Silane content influences physicochemical properties in nanostructured model composites.

OBJECTIVE: To determine the effect of organosilane content on the physicochemical properties of model composites formulated with nano-sized fillers. METHODS: Model composites were formulated with dimethacrylate-based monomers, a photoinitiator/co-initiator system and silicon dioxide nano-sized fillers treated with different amounts of 3-methacryloxypropyltrimethoxysilane (MPTS): 1.0 (G1%), 2.0 (G2%), 5.0 (G5%), 7.5 (G7.5%) and 10 (G10%) wt.% relative to SiO2. Non-silanized fillers (G0%) were used in the control group. Degree of conversion (DC) was assessed by Fourier-transformed infrared spectroscopy (ATR-FTIR). Knoop hardness (KHN) and elastic modulus were determined before and after water storage for 4 months. Water sorption (Wsp) and solubility (Wsl) were calculated by successive mass determinations in analytical balance. Surface gloss and roughness were characterized before and after toothbrushing simulation. RESULTS: With the exception of those fillers treated with 1% MPTS, DC was not dependent on the silane content. Within the silanized groups, G1% showed the lowest initial and final KHN, without statistical difference from G0%. The elastic modulus was not affected by the silane content, regardless of the storage condition, but those groups formulated with at least 5% silane presented improved values after storage. Silane content did not affect the WSl, but affected Wsp, in which those groups formulated with at least 2 wt.% of MPTS produced a more resistant material than G0%. The use of treated particles with at least 2 wt.% of silane was able to produce materials that did not change their gloss after the brushing process. Additionally, these materials presented lower surface roughness than G0% after the brushing process (p < 0.05). SIGNIFICANCE: The concentration of MPTS affected the physicochemical properties of nano-filled composites. Therefore, 2 wt.% of silane was the optimized quantity to produce materials resistant to degradation, both in bulk and surface properties.

Physicochemical properties and biological effects of quaternary ammonium methacrylates in an experimental adhesive resin for bonding orthodontic brackets

Abstract Fixed orthodontic appliances may lead to biofilm accumulation around them that may increase caries risk. This study aimed to evaluate the influence of quaternary ammonium methacrylates (QAMs) on the physicochemical properties, cytotoxicity, and antibacterial activity of adhesive resins for orthodontic purposes. Methodology: A base resin was prepared with a comonomer blend and photoinitiator/co-initiator system. Two different QAMs were added to the base adhesive: dimethylaminododecyl methacrylate at 5 wt.% (DMADDM) or dimethylaminohexadecyl methacrylate (DMAHDM) at 10 wt.%. The base adhesive, without QAMs, (GC) and the commercial Transbond™ XT Primer 3M (GT) were used as control. The resins were tested immediately and after six months of aging in the water regarding the antibacterial activity and shear bond strength (SBS). The antibacterial activity was tested against Streptococcus mutans via metabolic activity assay (MTT test). The groups were also tested for the degree of conversion (DC) and cytotoxicity against keratinocytes. Results: The resins containing QAM showed antibacterial activity compared to the commercial material by immediately reducing the metabolic activity by about 60%. However, the antibacterial activity decreased after aging (p<0.05). None of the groups presented any differences for SBS (p>0.05) and DC (p>0.05). The incorporation of DMADDM and DMAHDM significantly reduced the keratinocyte viability compared to the GT and GC groups (p<0.05). Conclusion: Both adhesives with QAMs showed a significant reduction in bacterial metabolic activity, but this effect decreased after water aging. Lower cell viability was observed for the group with the longer alkyl chain-QAM, without significant differences for the bonding ability and degree of conversion. The addition of QAMs in adhesives may affect the keratinocytes viability, and the aging effects maybe decrease the bacterial activity of QAM-doped materials.

Thiourethane-functionalized fillers: biological properties and degradation resistance

Abstract This study determined the effect of thiourethane-functionalized fillers (TU) on the antimicrobial properties, cytotoxicity, degree of conversion (DC), water sorption (Wsp) and solubility (Wsl) of experimental composites. TU-modified fillers were added at different ratios in experimental composites: 0 (Control-TU0), 25% (TU25), 50% (TU50), 75% (TU75) and 100wt% (TU100). The antimicrobial properties were detected through the exhaustion test and counting of Streptococus mutans colonies for biofilm formation. Cytotoxicity to human gingival fibroblasts was evaluated in three different parameters: XTT (2,3-Bis-(2-Methoxy-4-Nitro-5-Sulfophenyl)-2H-Tetrazolium-5-Carboxanilide), NRU (Neutral Red Uptake assay) and CVDE (Crystal Violet Dye Exclusion test)) at the same cells. ELISA was used to measure the IL-6 and b-FGF biomarkers. DC was determined by Fourier-transformed infrared spectroscopy, while Wsp and Wsl by mass variations. Inhibitory capacity of biofilm formation was not observed for any material. All groups presented at least 70% of cell survival within the observed periods (24h and 7 days). Positive control (toxic) had high IL-6 values and low b-FGF values. No significant variations in DC, Wsp, and Wsl were observed among the experimental groups. The use of thiourethane did not present antimicrobial and cytotoxic activity and the tested materials presented equivalent properties to those conventionally used in dentistry.

Thiourethane-functionalized fillers: biological properties and degradation resistance.

This study determined the effect of thiourethane-functionalized fillers (TU) on the antimicrobial properties, cytotoxicity, degree of conversion (DC), water sorption (Wsp) and solubility (Wsl) of experimental composites. TU-modified fillers were added at different ratios in experimental composites: 0 (Control-TU0), 25% (TU25), 50% (TU50), 75% (TU75) and 100wt% (TU100). The antimicrobial properties were detected through the exhaustion test and counting of Streptococus mutans colonies for biofilm formation. Cytotoxicity to human gingival fibroblasts was evaluated in three different parameters: XTT (2,3-Bis-(2-Methoxy-4-Nitro-5-Sulfophenyl)-2H-Tetrazolium-5-Carboxanilide), NRU (Neutral Red Uptake assay) and CVDE (Crystal Violet Dye Exclusion test)) at the same cells. ELISA was used to measure the IL-6 and b-FGF biomarkers. DC was determined by Fourier-transformed infrared spectroscopy, while Wsp and Wsl by mass variations. Inhibitory capacity of biofilm formation was not observed for any material. All groups presented at least 70% of cell survival within the observed periods (24h and 7 days). Positive control (toxic) had high IL-6 values and low b-FGF values. No significant variations in DC, Wsp, and Wsl were observed among the experimental groups. The use of thiourethane did not present antimicrobial and cytotoxic activity and the tested materials presented equivalent properties to those conventionally used in dentistry.

Membranas e barreiras para regeneração óssea guiada / Membranes and barriers for guided bone regeneration

Introdução: a evolução das técnicas de reconstrução alveolar e dos biomateriais na regeneração óssea guiada (ROG), vêm trazendo consigo o desenvolvimento de novas membranas com diferentes características e propriedades. Objetivo: este trabalho tem como objetivo reunir dados das membranas utilizadas em procedimentos de ROG, presentes no mercado nacional, para facilitar ao clínico a escolha de um biomaterial que seja adequado ao procedimento planejado e com um desempenho favorável para a regeneração. Metodologia: foram incluídas 30 membranas para ROG registradas e regulamentadas pela Agência Nacional de Vigilância Sanitária (ANVISA). As empresas fabricantes foram contatadas para fornecer as informações dos seus respectivos produtos. Resultados: 30 membranas foram encontradas e tabuladas. Após a análise das informações obtidas pelos fabricantes, as mesmas foram classificadas nos seguintes itens: nome, empresa fabricante, origem, tempo de bioreabsorção, possibilidade de exposição ao meio bucal, diâmetro dos orifícios e apresentação. Discussão: as propriedades e características específicas de cada membrana podem determinar diferentes resultados, sendo importante para o profissional conhecer essas diferenças para selecionar os materiais mais indicados aos procedimentos de ROG de acordo com os objetivos de cada caso. Dessa forma, os resultados podem ser previsíveis e atender da melhor forma possível as expectativas do tratamento com embasamento científico. Conclusão: o presente estudo tabulou 30 membranas quanto as suas principais características, visando orientar os profissionais da saúde na seleção da membrana mais adequada para alcançar seus objetivos no tratamento da ROG.

Introduction: the evolution of alveolar reconstruction techniques and biomaterials in guided bone regeneration (GBR), have brought with it the development of new membranes with different characteristics and properties. Objective: this study aims to gather data from the membranes used for ROG procedures present in the national market, to facilitate the clinician to choose a biomaterial that is suitable for the planned procedure and with a favorable performance for regeneration. Metodology: 30 membranes were included, registered and regulated by ANVISA. The manufacturing companies were contacted to provide information on their respective products. Results: 30 membranes were found and tabulated after analyzing the information obtained by the manufacturers, they were classified in the following items: name, manufacturer company, origin, time of resorption, possibility of exposure to the oral environment, diameter of the holes and presentation. Discussion: the specific properties and characteristics of each membrane can determine different results and, therefore, it is important for the professional to know these differences in order to select the most suitable materials for the GBR procedures according to the objectives of each case. In this way, the results can be predictable and best meet the expectations of the treatment with a correct scientific basis. Conclusion: the present study tabulated 30 membranes as to their main characteristics, aiming to guide health professionals in the selection of the most appropriate membrane to achieve their goals in the treatment of GBR.

Avaliação da deformação do preparo de superfície de implantes dentários submetidos a diferentes intensidades de torque / Deformation analysis of the surface preparation in dental implants submitted to different torque intensities

Introdução: o aprimoramento do processo de osseointegração faz com que os investimentos em pesquisa e o desenvolvimento de novos materiais e tratamentos de superfície sejam despendidos para promover a relação entre osso e implante. Uma das condições para o sucesso é a ausência de micromovimentos ou estabilidade primária da peça implantada, fato esse que leva alguns cirurgiões a aplicar torques excessivos sobre o implante, podendo resultar em danos ao tratamento aplicado à superfície externa do mesmo. Objetivo: o presente trabalho investigou possíveis níveis de deformação do preparo de superfície conforme diferentes valores de torque foram aplicados à dois sistemas de implantes para avaliar os possíveis danos causados. Metodologia: foram instalados 5 implantes do sistema Dérig e 5 implantes do sistema Straumann em um bloco de poliuretano, para posterior remoção com contra-torque e avaliação da superfície sob o Microscópio Eletrônico de Varredura (MEV). Resultados: nos resultados obtidos, no grupo de implantes Dérig não foi possível constatar evidências que comprovem que a elevação dos valores de torque aplicados aos implantes até 95 Ncm danifiquem ou alterem a estrutura do preparo de superfície externa dos implantes, contudo, no grupo Straumann, verificamos danos e alterações no preparo de superfície com torque progressivo a partir de 50 Ncm. Conclusão: possíveis alterações e danos ao preparo de superfície de implantes que apresentem rugosidade de superfície aumentada por jateamento podem ocorrer em torques acima de 50 Ncm empregados com o objetivo de aumentar sua estabilidade primária.

Introduction: improving the osseointegration process means that investments in research and development of new materials and surface treatments are expended to promote the relationship between bone and implant. One of the conditions for success is the absence of micromovements or primary stability of the implanted part. This fact causes some surgeons to apply excessive torque to the implant, which may result in damage to the treatment applied to the external surface of the implant. Objective: The present work investigated possible surface preparation deformation levels as different torque values were applied to two implant systems to evaluate the possible damage caused. Methodology: ive Dérig system implants and five Straumann system implants were installed in a polyurethane block for subsequent counter-torque removal and surface evaluation under the Scanning Electron Microscope (SEM). Results: Iin the obtained results, in the Dérig implant group it was not possible to verify evidences that the increase of the torque values applied to the implants up to 95 Ncm could damage or alter the structure of the external surface preparation of the implants, however, in the Straumann group we verified damage and changes in surface preparation with progressive torque from 50 Ncm. Conclusion: possible alterations and damages to the surface preparation of implants that present increased surface roughness by blasting can occur in torques above 50 Ncm employed in order to increase their primary stability.