Quintessence International, 04/1996

A new technical procedure for fixed partial dentures and single inlays allows the use of a metal supporting structure with independent ceramic coverage. The advantages of the technique are the bonding of metal to beveled dentinal margins with conventional cement and the acid-etched resin composite cementation of the ceramic, which permits more conservative preparation of the teeth. The complexity of the structure, the laboratory costs, and the doubling of the cementation procedures are the main disadvantages of the technique.

A patient in whom gingival hyperplasia was caused by prolonged use of an anticonvulsant drug (hydantoin) is described. Advanced gingival hyperplasia and significant displacement of the remaining teeth caused severe damage, especially to the patient's appearance. It was not possible to cure the problems completely with routine periodontal treatment. It was decided to extract all the remaining teeth and restore function and esthetics early with complete dentures. Cephalometric analysis was used to determine the degree to which the teeth had drifted. During fabrication of the dentures, the analysis was very useful in deciding the position of the anterior teeth and checking the vertical dimension of occlusion.

The article describes a new technique for fabricating a wedge directly in the mouth during clinical procedures. It is called a passive wedge because it is kind to the soft tissues, exerting neither compression nor traction on them. A conventional rigid wedge may hurt the interdental papilla, initiating bleeding and the flow of fluids through the rubber dam. This new technique is very useful during adhesive procedures, because the wedge prevents moisture from invading the working area and the cavity, maintains the matrix in place, and causes no harm to the soft tissues, allowing the restoration to be finished properly.

The tunnel preparation is among the techniques proposed for restoration of approximal carious lesions. The preparation minimizes the sacrifice of sound tooth structure. The diagnostic and management problems associated with the restricted access to the approximal area, however, have limited use of this treatment modality. The difficulty of ascertaining the possible loss of enamel surface integrity is overcome by temporary tooth separation, which permits direct visual and tactile examination of approximal sites. Additionally, the increased access facilitates both preparation of the cavity and placement of the restorative material.

Polymerization shrinkage of resin composite at the margin can seriously decrease the longevity of the restoration. Three direct restorative techniques were evaluated for their effects on microleakage. Sixty Class V cavities were prepared in extracted human maxillary molar teeth. The cavities were restored with resin composite placed in one bulk increment, resin composite and a beta-quartz insert, or resin composite and a prepolymerized resin composite ball insert. After they were themocycled and placed in 0.5% basic fuchsin for 24 hours, the specimens were sectioned and examined for microleakage. The restorations with a prepolymerized ball of resin composite exhibited significantly more microleakage than did restorations with a beta-quartz insert or restorations inserted in bulk.

It is important to know how much heat is generated when a root surface is debrided with sonic scalers and if that heat can be released satisfactorily into the environment. The temperature changes that occurred in dentinal specimens treated with two different sonic scaler tips, used with and without coolant, were studied. Temperature increases of up to 4 degrees C were observed for both tips when a coolant was used. Heat propagation during instrumentation was dependent to a considerable degree on the temperature of the coolant. Sonic scalers should not be used without coolant, because the dentinal temperature may increase up to 35 degrees C, depending on the force of application. A high positive linear correlation was found between increase in temperature and force of application.

Two Class II boxes of standarized dimensions were prepared in each of 10 extracted third molar teeth. The dentinal adhesives Syntac, Gluma 2000, Scotchbond MP, and All-Bond 2 were applied to five boxes each. All the boxes were restored with the same photopolymerizing resin composite. The microleakage of each restoration was measured ina permeability cell. The physiologic solution able to seep between the walls of the cavity and resin composite was measured and the flux of the liquid over time was calculated. All-Bond 2 was the only adhesive found, in some specimens, to make the dentin completely impermeable and to form an extremely precise seal between the resin composite material and the underlying dentinal surface. The flux values for all four adhesives were significantly different; Syntac allowed the greatest amount of microleakage. However, these in vitro results should not be considered absolute values.

Beta-quartz glass-ceramic inserts are a recent attempt to counteract some of the detrimental mechanical properties of resin composites by decreasing polymerization shrinkage and increasing wear resistance. The purpose of this study was to evaluate how manipulation, contamination, and disinfection would affect the resin composite-beta-quartz insert interface, as determined by microleakage. Seven groups (n = 10) of Class V cavity preparations were placed in extracted human molar teeth and restored with a microfilled resin composite and beta-quartz insert. In six groups, contamination or disinfection - latex glove, bare finger, human saliva, 95% ethanol, or LpHse disinfectant - was applied to the insert prior to placement. Latex gloves, bare fingers, and saliva were found to have a detrimental effect on the insert-resin composite interface that could compromise the longevity of the restoration.

The effects on surface roughness of three specific classifications of abrasive motion during the polishing of selected amalgam and resin composite materials were evaluated with a profilometer. Equivalent grit sizes were used to evaluate the character of the surface created by each class of abrasive motion. The motions investigated were rotary (diamond), planar (sandpaper disk), and reciprocal (reciprocating handpiece). Fine, medium, and coarse abrasives were used with each motion. Average roughness values for each abraded specimen were used to compare the effects of the type of motion on the surface. Results indicated that, amonga ll of the combinations of motions and abrasive grits evaluated, the planar motion produced significantly lower surface roughness values on both amalgam and resin composite surfaces.