Quintessence International, 04/1993

A single discolored tooth is often difficult to treat, but one with an obliterated pulp chamber and root canal presents an even greater challenge. The use of nightguard bleaching is offered as a simpler, alternative treatment to either root canal therapy or the removal of sound tooth structure for fabrication of a facial veneer or a complete-coverage crown.

This paper, the third of series, describes additional modified rubber dam utilizations that are generally not attempted with restrictive orthodox application methods. Part III offers practical hints and other means of retention with the emphasis on pedodontic applications.

A review is presented of some of the techniques available for removing restorations and foreign objects from root canals. Consideration is given to the removal of root restorations, sealers, and root canal obstructions, including fractured instruments and intact or broken posts and cores.

After the limitations of dental camera systems with regard t their lens and their flash unit are explained, a point-ring-flash combination is presented. The flash was tested in practical use and by systematic test shots. The flash combination allows the dentist to use a point flash or a ring flash alternatively. Nearly all problems in dental photography can be solved by using this equipment.

A rising geriatric population remains dentate and requires more dental care to maintain dental health and function. This article discusses psychological spects of aging and considerations of age-related changes of teeth, oral tissues, nutrition, and metabolism in the elderly. Aging affects all tissues and systems, as do nutritional and metabolic factors. Numerous factors alter healing, host resist ance, digestion and absorption, mastication, metabolic competency, renal and hepatic function, and excretory capability. Complex drug regimens further confuse clear diagnoses. Full consideration must be given these factors before treatment plans are formulated.

The importance of placing identification marks on dentures has long been acknowledged by the dental profession. More recently, following the fatalities at the Bradford City, England, football club fire, the need for marking dentures has been made more public. This paper outlines the different types of marking systems available and describes a survey of denture wearers to investigate their attitude toward the placement of identification marks on dentures. Results show that few dentures are marked at manufacture but that wearers are in favor of having their name on their denture. Of the 63 subjects sampled, 93.5% did not know that identification marks could be placed on dentures. The profession must be encouraged to routinely label all dentures at manufacture.

The purpose of this project was to test the in vitro bond strength of three dentinal bonding agents to primary dentin. Scotchbond 2, All-Bond, and Amalgambond were applied to 63 teeth according to manufacturer's instructions. Valux composite resin was placed in a cylindrical matrix and light cured to the treated dentin. After they were thermocycled for approximately 800 cycles between 6 degrees C and 60 degrees C, the specimens were mounted in stone and placed in an Instron universal testing machine. They were placed under continuous load until failure. Fracture was at the dentin-bonding agent interface for all materials tested. Incisor bond strength was significantly stronger than molar bond strength for all three materials. Materials analysis revealed that the mean bond strength for Scotchbond 2 (6.99 MPa) was significantly different from those of All-Bond (13.01 MPa) and Amalgambond (13.03 MPa).

Trismus is a condition that impairs eating, interferes with oral hygiene, restricts access for dental procedures, and may adversely affect speech and facial appearance. The success of treatment depends on recognition of the cause and initiation of appropriate management. Ideally, trismus appliances are used in conjunction with physical therapy and are most effective when the condition is the result of muscle fibrosis or scar tissue that has not yet matured. Trismus appliances act either externally or internally, and the forces they impart can be continuous or intermittent, light or heavy, and elastic or inelastic. Six applainces have been described in the literature. A seventh appliance, a plastic tapered cylinder, is also effective. The tapered cylinder relies on the patient's depressor muscles to separate the jaws, and allos easy appreciation of the progress made. The stretching force applied with this appliance is limited by the strength of the patient's depressor muscles.

The wall-to-wall contraction of the cementing layer of bonde restorations is compensated for mainly by elastic and plastic tooth substrate-cement deformation but may result in adhesive fracture. Occlusally flattened teeth and corresponding computer-designed onlays, both positioned in a special device, were used to study marginal and intenal seal of the adhesive interface with respect to four variables: rigidity of the restoration-substrate setup, cement thickness, adhesive configureation (enamel-dentin ratio and bonding agent), and luting agent. The results of dye infiltration tests revealed the significant influence of the adhesive configureation and rigidity of the setup. A high enamel-dentin ratio, use of a dentinal adhesive on dentinal margins and relative restoration-substrate mobility are required to preserve satisfactory marginal seal. However, in the present experimental conditions, no statistically significant differences were found among the diverse cement thicknesses or the luting agents evaluated.