The interaction of polyacid-modified composite resins ("compomers") with aqueous fluoride solutions

OBJECTIVE: The aim of this study was to investigate how the release of fluoride from two compomers and a fluoridated composite resin was affected by exposure to KF solution. MATERIAL AND METHODS: Two compomers (Dyract AP and Compoglass F) and one fluoridated composite (Wave) were prepared as discs (6 mm diameter and 2 mm thick), curing with a standard dental lamp. They were then stored in either water or 0.5% KF for 1 week, followed by placement in water for periods of 1 week up to 5 weeks total. Fluoride was determined with and without TISAB (to allow complexed and decomplexed fluoride to be determined), and other ion release (Na, Ca, Al, Si, P) was determined by ICP-OES. RESULTS: Specimens were found not to take up fluoride from 100 ppm KF solution in 24 h, but to release additional fluoride when stored for up to five weeks. Compomers released more fluoride cumulatively following exposure to KF solution (p<0.001), all of which was decomplexed, though initial (1 week) values were not statistically significant for Dyract AP. Other ions showed no variations in release over 1 week, regardless of whether the specimens were exposed to KF. Unlike the compomers, Wave showed no change in fluoride release as a result of exposure to KF. CONCLUSIONS: Compomers are affected by KF solution, and release more fluoride (but not other ions) after exposure than if stored in water.

Marginal adaptation and performance of bioactive dental restorative materials in deciduous and young permanent teeth

Objective: The aim of this study was to investigate the adaptation of different types of restorations towards deciduous and young permanent teeth. Materials and Methods: Class V cavities were prepared in deciduous and young permanent teeth and filled with different materials (a conventional glass-ionomer, a resin-modified glass-ionomer, a poly-acid-modified composite resin and a conventional composite resin). Specimens were aged in artificial saliva for 1, 6, 12 and 18 months, then examined by SEM. Results: The composite resin and the polyacid-modified composite had better marginal adaptation than the glass-ionomers,though microcracks developed in the enamel of the tooth. The glass-ionomers showed inferior marginal quality and durability, but no microcracking of the enamel. The margins of the resin-modified glass-ionomer were slightly superior to the conventional glass-ionomer. Conditioning improved the adaptation of the composite resin, but the type of tooth made little or no difference to the performance of the restorative material. All materials were associated with the formation of crystals in the gaps between the filling and the tooth; the quantity and shape of these crystals varied with the material. Conclusions: Resin-based materials are generally better at forming sound, durable margins in deciduous and young permanent teeth than cements, but are associated with microcracks in the enamel. All fluoride-releasing materials give rise to crystalline deposits.

Giovanni Battista Montano as Architectural Draughtsman: Recording the Past and Designing the Future

Giovanni Battista Montano (1534-1621), who was born in Milan and trained as a woodcarver, relocated permanently to Rome in the early 1570s where his interest in sculpting was replaced by intense study of the city’s antique monuments and ruins. Although Montano carried out several sculptural and architectural projects during his time in Rome, it is his surviving corpus of drawings that testifies to his passion of exploring ancient architecture through the medium of drawing. While Montano was not famous during his lifetime, a large body of his intriguing designs became celebrated and widely circulated after his death thanks to the 1624 publication of Montano’s designs by his loyal pupil, Giovanni Battista Soria. Montano’s lifelong work differs from virtually all of his predecessors and contemporaries in its “fantastical” and ornamental nature. This thesis explores Montano’s artistic training as it relates to his later interest in imaginatively reconstructing antique buildings, along with his disregard for archaeological or historical accuracy. The subject matter upon which Montano focused is discussed, along with his objective in creating a large corpus of half-historical, half-invented drawings. His drawing techniques are explored with specific reference to the largest group of extant Montano drawings, today housed in Sir John Soane’s Museum, London, England, and also in reference to three original Montano drawings in the Centre Canadien d’Architecture/Canadian Centre for Architecture, Montréal. Also explored is the legacy and impact of Montano’s drawings and the later publications of his designs on the works of Roman Baroque architects, specifically Borromini and Bernini. This thesis ultimately attempts to understand the impact of the intellectual and artistic environment surrounding Montano in late sixteenth and early seventeenth century Rome, his drawing techniques, his choice of subject matter, and the reception that his unique works received from contemporary artists and intellectuals, along with those of the following generation.