Regional push-out bond strength and coronal microleakage of Resilon after different light-curing methods

The purpose of this study was to assess the push-out bond strength and coronal microleakage of the Epiphany (Pentron Clinical Technologies, Wallingford, CT) + Resilon (Resilon Research LLC, Madison, CT) obturation system with respect to different photoactivation methods used. Roots of human maxillary central incisors (n = 60) were prepared with 0.06 taper nickel-titanum rotary files to size 30. After application of the Epiphany sealer, the roots were obturated with Resilon cones. The specimens were randomly assigned into three groups (n = 10/group) according to the light-curing unit (LCU) used from the coronal aspect: (1) quartz-tungsten-halogen/40 seconds, (2) light-emitting diode/20 seconds, and (3) plasma arc/6 seconds. Thereafter, 2-mm thick horizontal sections (n = 3) were obtained from each specimen from the coronal to apical direction and subjected to push-out test at a crosshead-speed of 1mm/min. Failure modes were assessed quantitatively under a stereomicroscope and morphologically under a scanning electron microscope. The remaining 30 roots were used for the dye-leakage assessments. Both the type of LCU and the level of sectioning had significant effects on bond strength. The following statistical ranking was obtained for bond strength values: quartz-tungsten-halogen > light-emitting diode > plasma arc. Coronal microleakage of specimens cured with the plasma arc was significantly greater than those of other groups (p < 0.05).     

Hydrolysis of functional monomers in a single-bottle self-etching primer--correlation of 13C NMR and TEM findings

Self-etching primers/adhesives that combine acidic methacrylate monomers with water in a single bottle are hydrolytically unstable and require refrigeration to extend their shelf-lives. This study tested the null hypothesis that one year of intermittent refrigeration of a 4-MET-containing simplified self-etching primer does not result in hydrolytic changes that are identifiable by transmission electron microscopy and (13)C NMR spectroscopy. Human dentin was bonded with UniFil Bond immediately after being unpacked, or after one year of intermittent refrigeration at 4 degrees C. Fresh and aged primers were analyzed by NMR for chemical changes. Ultrastructural observations indicated that there was an augmentation in etching capacity of the aged adhesive that was not accompanied by resin infiltration or effective polymerization. New NMR peaks detected from the aged ethanol-based primer confirmed that degradation occurred initially via esterification with ethanol, followed by hydrolysis of both ester groups in the 4-MET. Hydrolysis of functional methacrylate monomers occurs despite intermittent refrigeration.     

An ectopic maxillary second molar

A bstract — A rarely encountered ectopic and dilacerate maxillary second molar is described. The tooth was found to be attached to the medial wall of the maxillary sinus. Its location is thought to be due to ankylosis consequent to injury sustained during infancy.     

THE HSA: A FOCUS FOR ADVANCING PRIMARY PREVENTIVE DENTAL PROGRAMS

In conclusion, as community agencies under P.L. 93-641 embark upon the definition of health status goals, health system goals, and program implementation, dentists have the opportunity to clarify and assist in developing a vigorous approach to meeting dental health needs through primary prevention. Insofar as public health dentistry is able to provide technical assistance and leadership at the local HSA and SHPDA levels, the powerful tools for change embodied in this law can be a force for promoting the oral health of our population.     

The flow-rate-dependent excretion of ionized calcium in human parotid saliva.

The total calcium content of parotid saliva is increased in various diseases. Because of methodological difficulties, little is known about the ionized calcium fraction although it might be of importance for the secretion of fluid and proteins. Using a new method with calcium-selective disc electrodes, which gives an easy and exact estimation of ionized calcium, the Ca²⁺ activity in pilocarpine-stimulated parotid saliva of 10 healthy males was measured. With increasing flow-rate (0.1–0.6 ml/min), the concentration of ionized calcium rose exponentially from 1.13 ± 0.36 mequiv./litre (0.57 ± 0.18 mmol/litre) to 1.76 ± 0.21 mequiv./litre. At higher flow-rates (up to 2.5 ml/min), a plateau was observed. The total calcium concentration and the ionic calcium concentration were closely correlated (r = 0.93) and the ratio ionic/total remained nearly constant at 0.54 at all flow-rates.     

Follow-up investigation of reconstruction of the alveolar process in the atrophic mandible.

In this article the results are presented of the reconstruction of the alveolar process with iliac crest bone grafts in 14 patients. In all cases in a second operation a vestibuloplasty and a floor-of-mouth plasty was done. After an average follow-up period of 39 months, almost complete resorption of the bone grafts was observed. The clinical results varied. To obtain better results and avoid complications like pain at the donor and graft sites, mental nerve disturbances and other major problems associated with bone grafting, we prefer to perform the visor osteotomy in the future.