Effect of fluoride, chlorhexidine or Nd:YAG on the progression of root dentin demineralization after removal of the demineralized organic matrix

Quantification of collagen degradation is an important parameter to evaluate dentin caries for preventive aid. Objectives: Evaluate preventive methods against root collagen degradation by the hydroxyproline assay (HYP) and microradiography technique (MRT). Methodology: Five bovine root dentin blocks were obtained and subjected to an artificial demineralization process by acetate buffer (pH 5) to induce carious lesion formation. Samples were subjected to the following therapeutic treatments: 1) 0.12% chlorhexidine for 1 min, 2) 2% fluoride for 1 min, 3) Nd:YAG Laser (400 μm diameter optical fiber, 10 Hz frequency, 60 mJ/pulse energy, 48 J/cm2 energy density, in noncontact mode for 10 s), 4) deionized water (control) for 1 min, 5) MRT control group (without treatment and removal of collagen). Samples were exposed to degradation by a collagenase enzyme for five days. The enzyme solution was collected, by colorimetry in a spectrophotometer, from the collagen matrix for the hydroxyproline release analysis. The same samples were subjected to an additional two days of demineralization to induce the progression of mineral loss. Samples were analyzed by MRT for the visualization of their degraded areas (estimation of lesion depth and mineral loss). ANOVA was applied to compare hydroxyproline release rates. MRT data were subjected to the Kruskal-Wallis test, followed by the Dunn’s test. Comparisons between the initial five-day and the subsequent two-day demineralization processes were performed by repeated t-test or Wilcoxon (p<0.05) measurements. Results: The amount of HYP released from the dentin samples failed to show significant differences among the groups (p=0.09). Fluoride and chlorhexidine were able to interact with the samples, reducing the progression of dentin caries after removal of the demineralized organic matrix. CHX was the only treatment able to show significant lower lesion depth than the negative control. Conclusion: Chlorhexidine and fluoride were effective in reducing root caries progression

Efeito do tratamento dentinário com hipoclorito de sódio pós condicionamento ácido na resistência adesiva de restaurações em resina composta

Introduction: The development of squamous cell carcinoma of oral cavity (SCC) is a multifactorial process, where the cellular mutagenesis is determined by co-carcinogenetic agents like the human papillomavirus (HPV). Objective: the objective of this study is to identify the HPV in the SCC by means of polymerase chain reaction (PCR). Methods: twenty cases of SCC have been analyzed where the material used was extracted from specimens included in paraffin blocks of the Pathology Laboratory file of the São Vicente de Paulo Hospital of Passo Fundo/RS in the period of 2003 to 2007. They were all male cases and the 6th decade of life was the most prevalent. The lower lip was the region that comprises most of the defects and the histological grade "well-differentiated" from the World Health Organization was predominant. It has been detected the presence of HPV's DNA in four of the 20 cases of the SCC (20%). Conclusions: it can be assured that, by the fact of the HPV has been identified in a considerable percentage of cases of SCC, it can have influence on the genesis of the referred malignant neoplasia. So, more studies are necessary to define what is the possible role of HPV in the oral carcinogenesis. Este trabalho teve como objetivo avaliar a resistência adesiva de restaurações de resina composta, mediante a remoção ou não do colágeno dentinário. Para tanto, foram utilizados 24 dentes bovinos, embutidos em resina acrílica e desgastados até se obter um remanescente de 2mm de dentina. Delimitou-se a área da adesão em 3mm de diâmetro. As amostras foram divididas em 2 grupos: G1 (controle): foi aplicado o sistema adesivo autocondicionante Adper Prompt L-Pop (3M ESPE), seguindo as recomendações do fabricante, e procedida a restauração com a resina Z100 (3M) pela técnica incremental, em matriz metálica e sobre a área preparada; G2 (teste): realização de condicionamento com ácido fosfórico 37% por 15s, lavagem, secagem, aplicação de hipoclorito de sódio (NaOCl) 10% por 60s, lavagem, secagem, aplicação do sistema adesivo autocondicionante e realização da restauração, como descrito anteriormente. Os espécimes foram imersos em água destilada e mantidos em estufa bacteriológica a 37ºC por 7 dias, e então submetidos ao teste de cisalhamento em uma máquina de ensaio universal EMIC (velocidade de 0,5mm/min). Após análise estatística (ANOVA e teste T), os valores médios encontrados foram: G1=8,32±2,28 MPa e G2=5,76±2,48MPa (p

Mechanical-physicochemical properties and biocompatibility of catechin-incorporated adhesive resins

Several anti-proteolytic dentin therapies are being exhaustively studied in an attempt to reduce dentin bond degradation and improve clinical performance and longevity of adhesive restorations. Objectives: This study assessed the effect of epigallocatechin-3-gallate (EGCG) on long-term bond strength when incorporated into adhesives. Material and Methods: Adhesive systems were formulated with EGCG concentrations of 0 wt%: (no EGCG; control); 0.5 wt% EGCG; 1.0 wt% EGCG, and 1.5 wt% EGCG. Flexural strength (FS), modulus of elasticity (ME), modulus of resilience (MR), compressive strength (CS), degree of conversion (DC), polymerization shrinkage (PS), percentage of water sorption (%WS), percentage of water solubility (%WL) and cytotoxicity properties were tested. Dentin microtensile bond strength (µTBS) was evaluated after 24 h and again after 6 months of water storage. The adhesive interface was analyzed using scanning electron microscopy (SEM). Results: No significant differences were found among the groups in terms of FS, ME, MR, CS and PS. EGCG-doped adhesives increased the DC relative to the control group. EGCG concentrations of 1.0 wt% and 0.5 wt% decreased the WS of adhesives. WL decreased in all cases in which EGCG was added to adhesives, regardless of the concentration. EGCG concentrations of 1.0 wt% and 0.5 wt% reduced cytotoxicity. EGCG concentrations of 1.0 wt% and 0.5 wt% preserved µTBS after 6 months of storage, while 1.5 wt% EGCG significantly decreased µTBS. SEM: the integrity of the hybrid layer was maintained in the 0.5 wt% and 1.0 wt% EGCG groups. Conclusion: EGCG concentrations of 1.0 wt% and 0.5 wt% showed better biological and mechanical performance, preserved bond strength and adhesive interface, and reduced cytotoxicity

Proteins, Pathogens, and Failure at the Composite-Tooth Interface

In the United States, composites accounted for nearly 70% of the 173.2 million composite and amalgam restorations placed in 2006 (Kingman et al., 2012), and it is likely that the use of composite will continue to increase as dentists phase out dental amalgam. This trend is not, however, without consequences. The failure rate of composite restorations is double that of amalgam (Ferracane, 2013). Composite restorations accumulate more biofilm, experience more secondary decay, and require more frequent replacement. In vivo biodegradation of the adhesive bond at the composite-tooth interface is a major contributor to the cascade of events leading to restoration failure. Binding by proteins, particularly gp340, from the salivary pellicle leads to biofilm attachment, which accelerates degradation of the interfacial bond and demineralization of the tooth by recruiting the pioneer bacterium Streptococcus mutans to the surface. Bacterial production of lactic acid lowers the pH of the oral microenvironment, erodes hydroxyapatite in enamel and dentin, and promotes hydrolysis of the adhesive. Secreted esterases further hydrolyze the adhesive polymer, exposing the soft underlying collagenous dentinal matrix and allowing further infiltration by the pathogenic biofilm. Manifold approaches are being pursued to increase the longevity of composite dental restorations based on the major contributing factors responsible for degradation. The key material and biological components and the interactions involved in the destructive processes, including recent advances in understanding the structural and molecular basis of biofilm recruitment, are described in this review. Innovative strategies to mitigate these pathogenic effects and slow deterioration are discussed

Treatment of traumatized permanent incisors with crown and root fractures: A case report

A case report of the treatment of permanent incisors with crown and root fractures is presented. A radiolucent lesion at the fracture lines was treated with calcium hydroxide in the coronal fragments for 18 months. Clinically, the teeth became firm and the radiographic results after 2 years showed healing of the lesion and hard tissue filling in the space at the fracture lines. © Munksgaard, 2001