Influence of photosensitizing agent and number of photodynamic therapy sessions on resistance of fiberglass posts to displacement within the canal

Aim: To evaluate the influence of the type of photosensitizing agent and the number of photodynamic therapy (PDT) sessions on the resistance of cemented fiberglass posts to displacement within the root canal. Methodology: Fifty bovine primary incisors were randomly divided into five experi-mental groups according to the type of photosensitizing agent and to the number of PDT sessions: CG without PDT (control); GF1M one PDT session with methylene blue; GF2M two PDT sessions with methylene blue; GF1T one PDT session with toluidine blue; and GF2T two PDT sessions with toluidine blue. Exacto® fiberglass posts were cemented with RelyX U200® in the root canal and kept for 15 days in distilled water. The specimens were sectioned with an average thickness of 1.56 mm at the cervical, middle, and apical root thirds and subjected to the push-out test. After the test, the fractured specimens were analyzed under a stereomicroscope to determine the fracture pattern. The data obtained were treated by one-way ANO-VA (α=0.05). Results: There was no statistical difference in the comparison of the proposed treatments and the analyzed root thirds (P>0.05). Conclusions: The type of photosensitizing agent used and the number of PDT sessions do not influence the resistance of cemented intraradicular fiberglass posts to dis-placement

Effect of different methods of fiber post cleaning on post resistance to dislodgement from the root canal

Aim: To evaluate the effect of different methods of fiber post cleaning on post resistance to dislodgement after cementation. Methodology: Sixty bovine incisors were divided into six groups according to the cleaning method applied to the fiber posts. GC: no cleaning; GES: autoclave sterilization; GHP: 2.5% sodium hypochlorite; GCL: 2% chlorhexidine digluconate; GAL: 70% alcohol; GAF: 35% phosphoric acid. The posts were cemented in the canals using a self-adhesive resin cement. The specimens were sectioned perpendicularly along the long axis of the root with an av-erage thickness of 1.61 mm at the cervical, middle, and apical root thirds and subjected to the push-out test. After the test, they were examined under a stereomicroscope to de-termine failure mode. Data were analyzed using one-way ANOVA and the Tukey test (α=0.05). Results: The comparisons with the GC group revealed statistical differences only in the middle and apical thirds of the GCL group and in the apical third of the GHP group. Only the apical thirds were different from the middle and cervical thirds in the GC group, and the cervical thirds, from the middle and apical thirds of the GES group. Conclusions: The resistance to dislodgement of fiber posts cemented in root canals was not affected by the different cleaning methods under study

Surface and mechanical properties of adhesives with calcium phosphates challenged to different storage media

To evaluate the behavior of experimental dental adhesives with hydroxyapatite (HAp), alpha-tricalcium phosphate (α-TCP) or octacalcium phosphate (OCP) after storing them in three different media: dry storage, distilled water, or lactic acid. Methods: An experimental adhesive resin was formulated with bisphenol A glycol dimethacrylate, 2-hydroxyethyl methacrylate, and photoiniciator/co-initiator system. HAp (GHAp), α-TCP (Gα-TCP), or OCP (GOCP) were added to the adhesive resin at 2 wt.%, and one group remained without calcium phosphates to be used as a control (GCtrl). The adhesives were evaluated for surface roughness, scanning electron microscopy (SEM), and ultimate tensile strength (UTS) after storing in distilled water (pH=5.8), lactic acid (pH=4) or dry medium. Results: The initial surface roughness was not different among groups (p>0.05). GHAp showed increased values after immersion in water (p<0.05) or lactic acid (p<0.05). SEM analysis showed a surface variation of the filled adhesives, mainly for Gα-TCP and GHAp. GHAp showed the highest UTS in dry medium (p<0.05), and its value decreased after lactic acid storage (p<0.05). Conclusions: The findings of this study showed that HAp, OCP, and α-TCP affected the physical behavior of the experimental adhesive resins in different ways. HAp was the calcium phosphate that most adversely affected the surface roughness and the mechanical property of the material, mainly when exposed to an acid mediu

Evaluation of guanidine antifungal solutions for denture base resin: an in vitro study

Antecedentes: Os objetivos deste estudo foram: (1) formular soluções de cloridrato de polihexametileno guanidina (PHM-GH) em diferentes concentrações; (2) avaliar sua atividade antifúngica contra biofilme maduro de Candida albicans em resinas acrílicas; (3) avaliar efeitos na resistência à flexão e rugosidade da superfície. Métodos: Soluções de PHMGH foram formuladas com água destilada e 0,125, 0,250 ou 0,5% em peso de PHMGH. Um grupo sem PHMGH foi usado como controle. Para análise da atividade antifúngica, amostras de resina acrílica foram contaminadas com C. albicans, e imersas em soluções de PHMGH ou água destilada por 5 ou 10 min. Resistência à flexão final e rugosidade da superfície foram avaliadas. Resultados: Todas as soluções de PHMGH aos 5 ou 10 minutos apresentaram atividade antifúngica em comparação ao grupo controle (pBackground: The purposes of this study were: (1) to formulate polyhexamethylene guanidine hydrochloride (PHMGH) solutions at different concentrations; (2) to evaluate their antifungal activity against a mature biofilm of Candida albicans on acrylic resins; (3) to evaluate possible effects on acrylic resins flexural strength and surface roughness. Methods: PHMGH solutions were formulated with distilled water and 0.125, 0.250, or 0.5 wt.% of PHMGH. One group without PHMGH was used as control. For antifungal activity analysis, acrylic resin specimens were contaminated with C. albicans. Specimens were immersed in PHMGH solutions or distilled water for 5 or 10 min. Ultimate flexural strength and surface roughness of acrylic resins were evaluated. Results: All PHMGH solutions at 5 or 10 min showed antifungal activity compared to the control group (