This study investigated the relationship of arginine deiminase (ADS) and urease activities with dental caries through a case-control study. ADS and urease activities were measured in dental smooth-surface supragingival plaque and whole saliva samples from 93 subjects, who were in three different groups: caries-free (n = 31), caries-active (n = 30), and caries-experienced (n = 32). ADS activity was measured by quantification of the ammonia generated from the incubation of plaque and saliva samples in a mixture containing 50 mM arginine-HCl and 50 mM Tris-maleate buffer, pH 6.0. ADS-specific activity was defined as nanomoles of ammonia generated per minute per milligram of protein. Urease activity was determined by quantification of ammonia produced from 50 mM urea. For bacterial identification and enumeration real-time qPCR analysis was used. Groups were compared using Kruskal-Wallis tests. Spearman correlations were used to analyze plaque metabolic activity and bacterial relationships. The results revealed significantly higher ammonia production from arginine in saliva (1.06 vs. 0.18; p < 0.0001) and plaque samples (1.74 vs. 0.58; p < 0.0001) from caries-free subjects compared to caries-active subjects. Urease levels were about 3-fold higher in the plaque of caries-free subjects (p < 0.0001). Although higher urease activity in saliva of caries-experienced and caries-free subjects was evident, no significant difference was found between the groups.

SUMMARYThis study recorded the number of preclinical lecture and simulation laboratory sessions spent teaching the preparation and placement of amalgam and resin composite posterior restorations. These data were compared to the use of both materials in the operative clinic as placed by third-and fourth-year students. The number of posterior restorations inserted by the students, expressed as a function of the number of restoration surfaces, was also evaluated. The results show that the teaching of posterior restorations pre-clinically has consistently favored amalgam 2.5 to 1 during the last three years. However, clinically, resin composite is being used for posterior restorations 2.3 times more often than amalgam. The only instance that favored amalgam over composite during the last year was in the placement of four surface posterior restorations. This shift in emphasis from amalgam to composite needs to be addressed within dental educational institutions so that newly graduated dentists are prepared to place composite restorations properly. INTRODUCTIONThe didactic teaching and the clinical experience that students receive in the dental curriculum is limited, but it serves as the basis upon which newly graduated dentists start their own practice, work in an established practice or enter into a residency program. For decades, the curriculum in operative dentistry focused on amalgam as the predominant posterior restorative material and silicate cement as the anterior tooth-colored material. The change from silicate cement to resin based composite material as the predominant anterior restorative material occurred in the 1970s and repre-ME Ottenga • IA Mjör Clinical RelevanceThere is an undeniable move away from amalgam towards the use of resin composite restorations in posterior teeth. The data from one dental school suggests that dental curricula are not keeping pace with the clinical shift that has occurred.

This clinical report presents the use of a modified polyetheretherketone (PEEK) Inlay Retained Resin Bonded Fixed Dental Prosthesis (IRRBFDP) framework, veneered with indirect high impact composite for the bilateral restoration of mandibular first molar teeth, as the most conservative treatment option for a medically compromised patient. When used as a framework, PEEK's elastic modulus (approximately 4 GPa), could result in the reduction of stresses transferred to the abutment teeth and the cementation interface accordingly, therefore it could result in lower de‐bonding rates and higher success rates. Furthermore, the high bond strength with the veneering composite material and the luting cements permit its use for resin‐bonded restorations. Preparation guidelines, indications and advantages for the fabrication of IRRBFDPs are described in this clinical report. No technical complications such as de‐bonding of the framework, connector or retainer fracture of the adhesive frameworks or loss of retention were observed during the course of 8 years. Prosthetic replacement of single missing posterior mandibular teeth utilizing IRRBFDPs with high performance polymer materials could potentially offer long‐term high survival rate outcomes. Further clinical evidence is required in order to justify the above statement.

Objectives To assess the relationships among alkali production, diet, oral health behaviors, and oral hygiene.Methods Data from 52 subjects including demographics, diet, and oral hygiene scores were analyzed against the level of arginine and urea enzymes in plaque and saliva samples. An oral habit survey was completed that included: use of tobacco (TB), alcohol (AH), sugary drinks (SD), and diet. Alkali production through arginine deiminase (ADS) and urease activities were measured in smooth-surface supragingival dental plaque and un stimulated saliva samples from all subjects. ADS and urease activities were measured by quantification of the ammonia generated from the incubation of plaque or saliva samples. Spearman correlations were used to compute all associations.Results Participants in the lowest SES (Socio-economic status) group had the habit of consuming sugary drinks the most and had the highest rate of tobacco use. Males consumed significantly more alcohol than females. No significant relationship was found between age or gender and alkali production. Higher rates of sugary drink consumption and tobacco use were significantly related to lower alkali production.Conclusion The study showed a relationship between alkali production and oral hygiene, diet, and certain oral health behaviors. Poor oral hygiene was significantly associated with age, lower SES, tobacco use, and alcohol, and sugary drinks consumption.Clinical relevance Certain oral health behaviors have an impact on oral hygiene and on alkali production; it is important to address these factors with patients as a strategy for caries control.

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Clinical Relevance Radiographic lesion depth should not be used as the single determinant of the restorative threshold for clinically inaccessible approximal caries lesions. Temporary tooth separation is a feasible and effective diagnostic aid for assessment and appropriate management of approximal lesions.

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