Investigation of Conventional vs Nonoriginal CAD/CAM Bars with Production Stage Differences: An In Vitro Precision Study Using a Novel Technique.

PURPOSE: The aim of this study was to evaluate the precision of fit of bar frameworks fabricated using three different production processes and the effect of changes in the CAD/CAM process steps on the precision of the resulting bar frameworks. MATERIALS AND METHODS: Four implants were applied to a mandibular phantom model, and three different production techniques were used to fabricate 30 bar frameworks. In the first group, the bar frameworks were fabricated with the conventional production process (the lost-wax technique; n = 10). In the second group, a CAD/CAM production process was used with digital data collected individually from the master model for the production of each of the final bar specimens (n = 10). In the third group, a CAD/CAM production process was used with the master model being scanned once, and the single resulting data value was used for the production of all final bar specimens (n = 10). The marginal gap between bar frameworks and implants was digitally calculated (ATOS So High-End 3D Digitizer for Small Objects, GOM Inspect). Newman-Keuls multiple comparison tests, a Tukey multiple comparison test, and Pearson correlation tests were applied to the data with a level of significance of P < .05. RESULTS: The mean marginal gap value of group 1 was 95.25 ± 76.15 µm, which was statistically significantly lower than the other groups (P = .0001). For group 2, the mean marginal gap value was 152.00 ± 97.19 µm, whereas for group 3, the mean marginal gap value was 156.7 ± 78.70 µm. Among group 2 and group 3, no statistically significant difference was observed at the mean marginal gap value. CONCLUSION: The marginal gap values in the CAD/CAM bar framework groups were significantly higher than the conventional bar framework group. Among the CAD/CAM groups, the mean marginal gap values were not statistically significant.

Effect of dentin pretreatment on shear bond strength of three resin-based luting cements.

PURPOSE: The aims of this study were; to compare the shear bond strength values of resin-based luting cements using etch-and-rinse, self-etching or self-adhesive techniques and to evaluate the effects of pretreatment with 0.2%, and 2% chlorhexidine (CHX) solutions on the bonding stability to dentin. MATERIALS AND METHODS: Ninety specimens were divided into 9 groups of equal sample size (0.2% CHX, 2% CHX and no CHX application groups). Variolink N (multi-step etch-and-rinse technique), Panavia F2.0 (self-etching technique), or RelyX U200 (self-adhesive technique) resin-based luting cement was applied. All specimens were subjected to shear bond strength test (SBS) after bonding procedure. The mode of failure was analyzed by using a stereomicroscope. RESULTS: There were no significant differences among study groups for the dentin treatment factor. However, for luting cement factor, significant differences were found and Variolink N showed the highest SBS values. CONCLUSION: CHX application has no immediate effect on the SBS values of any resin cements. Despite the development of simplified cementation techniques, etch-and-rinse technique is still the most reliable technique because of its high bond strength to dentin.

Prevalence of Candida albicans and Streptococcus aureus on maxillary obturators, maxillary defects and in saliva: A cross-sectional study / Prevalência de Candida albicans e Streptococcus aureus em obturadores superiores, nos defeitos maxilares e na saliva: Um estudo transversal

Objetivo: este estudo investigou a incidência da adesão de Candida albicans e Staphylococcus aureus em próteses superiores obturadoras com materiais de reembasamento macio utilizados por protesistas. Material e Métodos: entre os anos 2013 e 2014, foram avaliados clinicamente, pacientes com defeitos maxilares devido a cirurgia para remoção de tumores e usuários de próteses obturadoras (n = 21, grupo de estudo) e, as consequências microbiológicas foram comparadas com usuários de prótese total superior (n = 21, controle grupo). Os dados foram coletados sobre características demográficas, tipo histológico de câncer, emprego de quimioterapia ou radioterapia, identificação dos materiais reembasamento macio utilizados e métodos de limpeza praticados nas próteses obturadoras e totais. A presença de Candida albicans foi determinada nos materiais de reembasamento macio ou nas superfícies de polimetilmetacrilato e na cavidade bucal e, Staphylococcus aureus na mucosa nasal e na saliva. Os dados foram analisados utilizando os testes Kruskal Wallis, Fisher-Freeman-Halton (p<0,05). Resultados: A maior quantidade de Candida albicans foi encontrada nas superfícies das próteses, na saliva, nos defeitos no palato duro e no material de reembasamento macio definitivo com 90%, 90% e 70%, respectivamente. A maior quantidade de Staphylococcus aureus foi observada na saliva e na cavidade nasal no grupo de material de reembasamento macio definitivo (50%). Conclusão: o curto período de renovação dos materiais de revestimento pode causar menos colonização de Candida albicans e estomatite protética na cavidade bucal. Os pacientes que sofreram maxilectomia foram mais propensos à colonização de Staphylococcus aureus.(AU)

Objective: This study investigated on the incidence of Candida albicans and Staphylococcus aureus adhesion onto maxillary obturator prostheses with soft lining materials placed by prosthodontists. Material and Methods: Between years 2013 and 2014, patients with maxillary defects due to maxillary tumor surgery and acquired obturator prostheses (n = 21, study group) were clinically evaluated and microbiological outcomes were compared with complete maxillary denture wearers (n = 21, control group). Data were collected on demographic features, histological type of cancer, presence of chemotherapy or radiotherapy, identification of soft lining materials used on obturator prostheses, cleansing methods practiced for obturator and maxillary complete prostheses. The presence of Candida albicans was determined on soft lining materials or polymethylmethacrylate surfaces and in the oral cavity, and Staphylococcus aureus in nasal mucosa and saliva. Data were analyzed using Kruskal Wallis, Fisher-Freeman-Halton tests (p<0.05). Results: The highest amount of Candida albicans was found on surfaces of prostheses, in the saliva and on maxillary defects on the hard palate and on definitive soft lining material with 90%, 90%, and 70%, respectively. The highest amount of Staphylococcus aureus was observed in the saliva and nasal cavity in the definitive soft lining material group (50%). Conclusion: Short renewal period of lining materials may cause less Candida albicans colonisation and denture stomatitis in the oral cavity. Patients who have undergone maxillectomy were more prone to Staphylococcus aureus colonisation.(AU)

Oral Rehabilitation of an Osteopetrosis Patient with Osteomyelitis.

Osteopetrosis is a congenital disorder characterized by increasing osteoclastic function resulting in osteomyelitis in the jaws. Orofacial findings in osteopetrosis patients are unerupted, malformed, or delayed teeth and many dental caries due to vulnerable enamel and dentin and osteomyelitis. Many reports have described that maxilla is an uncommon site of occurrence for osteomyelitis due to cortical bone morphology and collateral circulation. This report aims to discuss clinical features and prosthodontic management of a patient with clinical features of adult form of osteopetrosis and osteomyelitis in both jaws. The patient has reported better masticatory and speech efficiency with removable dentures in maxillary and mandibular jaw and also self-esteem improvement and family interaction.

Influence of acrylic resin polymerization methods on residual monomer release.

AIM: The aim of this study was to quantify and compare the amount of methyl methacrylate (MMA) monomer released from three different denture base acrylic material processed by different polymerization methods and storage conditions. MATERIALS AND METHODS: Microwave-cured, conventional heat and injection-technique acrylic polymerized materials were stored in neutral (pH = 7) and acidic (pH = 4.5) artificial saliva for 24 hours at the room temperature, separately. The residual MMA content was determined by high performance liquid chromatography (HPLC). RESULTS: The MMA leaching from resins showed that microwave-cured material has lower residual MMA leach compared both conventional and injection-technique on neutral saliva storage conditions. CONCLUSION: The all data's exhibited higher MMA release into an acidic saliva environment than neutral artificial saliva and there were no significant differences between the materials groups on acidic saliva storage conditions. CLINICAL SIGNIFICANCE: Microwave polymerization method might has some advantages on reducing release of MMA concentration and may contributory effect upon polymerization reaction on neutral pH storage condition, therefore methods of polymerization should be considered as amount of monomer release.