Tensile fatigue of two composite cements bonding three base metal alloys to bovine enamel.

Tensile fatigue endurance limits were determined for three base metals (Ni-Cr, Ni-Cr-Be, and Co-Cr) bonded to bovine enamel using two composite cements: a Bis-GMA/phosphate ester composite cement which relies on a sand-blasted metal surface, and a Bis-GMA composite luting cement which relies on electrolytically etched metal surfaces. Samples were tested to failure or to 10(6) cycles at 5 hz in Ringer's solution at 37 degrees C, and endurance limits were determined using a two-point test strategy. SEM evaluation was performed on fractured samples to determine failure mode. Statistical analysis of the results showed no difference between cements when using Ni-Cr-Be; however when using Co-Cr, the Bis-GMA/phosphate ester cement produced greater values than the Bis-GMA cement that relied on electrolytical etching. The opposite result occurred when a Ni-Cr alloy was tested with both cements. Evaluation of the results for each cement with the three different alloys showed statistical significant differences. SEM fracture analysis revealed a mixed failure pattern with apparent adhesive fracture from both the composite-enamel and composite-metal interfaces and cohesive failure throughout the cement.

Microleakage of new dentin bonding systems using human and bovine teeth.

The objective of this study was twofold: to evaluate the microleakage behavior of three dentin bonding systems and to determine if bovine teeth are comparable substrates to human teeth when studying the microleakage of various materials. The materials evaluated were Scotchbond Multi-Purpose Adhesive, Prisma Universal Bond 3, and All-Bond 2. All three bonding systems were used in combination with Prisma APH hybrid composite for comparison of microleakage behavior. Sixty class 5 preparations were cut at the cementoenamel junction for groups containing 30 human and 30 bovine teeth. A 1 mm 45 degree bevel was placed at the enamel margin. Teeth were grouped according to the dentin bonding system used and then restored according to the manufacturer's directions. After restoration, the teeth from each group were stored in distilled water at 37 degrees C for 3 days. The teeth were then thermocycled between 4 degrees C and 58 degrees C for 100 cycles and returned to distilled water at 37 degrees C for an additional 4 days. The teeth were then sealed with nail polish up to 1 mm from the margins of the restoration and placed in 45Ca isotope for 2 hours. The teeth were then sectioned and placed on x-ray film to produce autoradiographs. Microleakage was evaluated for the enamel and dentin margins separately using the following scale: 0 = no leakage, 1 = penetration of isotope to less than 1/2 the distance to the axial wall, 2 = penetration of isotope greater than 1/2 of the distance to the axial wall but short of the axial wall, and 3 = penetration of isotope to the axial wall or beyond. The materials were compared to each other using the Mann-Whitney U and Kruskal-Wallis tests. The gingival margins were compared to the incisal margins for all materials. No statistically significant differences in microleakage were revealed between the incisal and gingival location for human substrates, but there was statistically significant greater gingival microleakage for bovine substrates. All-Bond 2 leaked significantly more than Scotchbond Multi-Purpose for human substrates at the incisal margin. All-Bond 2 had significantly more microleakage than Prisma Universal Bond 3 at both dentin and enamel margins for the bovine substrate. There were no statistically significant differences in microleakage among the bonding systems for the human substrate. No statistically significant differences between the microleakage behavior of human and bovine substrates were found. These results support the use of bovine teeth for in vitro microleakage studies.

Microleakage of a new cavity varnish with a high-copper spherical amalgam alloy.

In a study in vitro Copalite and Barrier cavity varnishes were applied to the walls of class 1 prepared cavities before placing Tytin, a high-copper amalgam. Tests with 45Ca and autoradiographs showed that at six months only Copalite was effective in preventing microleakage. At one year neither Barrier nor Copalite was preventing leakage.

Microleakage of Gluma Bond, Scotchbond 2 and a glass ionomer/composite sandwich technique.

Bonding to dentin with long-term success has been a quest of dentistry for some time. Microleakage is a major problem that can lead to staining and discolorization of the restoration and postoperative sensitivity. Some of the newer dentin bonding systems include Gluma Bond and Scotchbond 2. A glass ionomer/composite "sandwich" technique has also been advocated for dentin bonding. Here a glass ionomer is first bonded to the dentin, bonding agent is applied to the glass ionomer and a composite restoration is then placed into the cavity preparation. The purpose of this study was to compare the microleakage of Gluma Bond, Scotchbond 2, the glass ionomer/composite sandwich technique along with a positive and negative control. This was accomplished, in vitro, using extracted human teeth and a Ca45 radioisotope technique. The teeth were examined for microleakage at periods of 1 week, 6 months and 12 months. The results of this study indicate that, in vitro, the glass ionomer sandwich technique does not stop microleakage. The results also indicate that, in vitro, Gluma Bond and especially Scotchbond 2 restorations can resist microleakage for short periods of time. However, at the end of the 12 months, all Gluma Bond and Scotchbond 2 specimens exhibited gross microleakage.

Evaluation of a new dentinal bonding system.

The purpose of this study was to compare the in vitro microleakage of a new dentinal bonding system, not yet released in the United States, to the microleakage of two first-generation bonding agents. Simulated Class V cavities were prepared in freshly extracted bovine incisors and restored with the appropriate composite resin-bonding agent combination. Restorations were thermocycled and examined for microleakage at 24 hours and 60 days. Comparison of the materials revealed no statistically significant difference in microleakage scores at the gingival or incisal margins after 24 hours. However, the first-generation bonding agents exhibited significantly more microleakage at the gingival margin than did the new bonding system after 60 days. No significant increase in microleakage was measured at the incisal margin for any of the materials after 60 days. In contrast, all materials exhibited a significant increase in leakage at the gingival margin after 60 days. No correlation between microleakage and polymerization shrinkage or coefficients of thermal expansion of the composite resins could be established.

Microleakage and thermal properties of hybrid ionomer restoratives.

The objective of this study was to compare the microleakage and thermal properties of two recently introduced hybrid materials to those of a conventional glass-ionomer cement. Class V preparations were prepared at the cementoenamel junctions in freshly extracted bovine incisor and evaluated for microleakage with a 45Ca radioisotope method. Thermal properties were evaluated with thermal mechanical analysis and differential scanning calorimetry. The degree of microleakage and the coefficient of thermal expansion of the conventional glass-ionomer cement were found to be significantly less than those of either hybrid.

Microleakage of a new dental adhesive comparing microfilled and hybrid resin composites.

The objective of this study was to evaluate the in vitro microleakage of a new adhesive system, Syntac. Class V preparations were cut at the cementoenamel junction in 20 extracted bovine incisors and 20 extracted human incisors. One group of 10 human and 10 bovine teeth was restored with Syntac and a microfilled posterior resin composite; the other group was restored with Syntac and a hybrid resin composite. Microleakage was evaluated at 1 week with a 45Ca radioisotope method. No statistically significant differences between human and bovine substrates were found with either resin composite. The Syntac/hybrid resin restorations leaked less than did the Syntac/microfilled resin restorations at the gingival (dentin) margin in the bovine teeth; however, this difference was not statistically significant.

Microleakage of two new dentinal bonding systems.

Class V abrasion and erosion lesions restored with composite resin seem to be more susceptible to microleakage, because the gingival margin is usually placed in cementum and/or dentin. The purpose of this study was to evaluate the microleakage, in vitro, of two new dentinal bonding systems along with a positive and negative control. This study was accomplished using extracted human teeth and a calcium-45 radioisotope technique. The teeth were examined for microleakage at periods of 1 week, 6 months, and 1 year. The results at all time intervals indicated that the cavities restored with the new bonding agents and their respective composite resins leaked more than did the negative control, glass-ionomer cement.

Oral trauma. Emergency care of lacerations, fractures, and burns.

Emergency physicians are usually the first to see patients with injuries to oral and facial tissues. Because many of these patients may have life-threatening neurologic injuries, secondary oral and perioral problems may be overlooked initially. These injuries, however, have a profound potential for causing lifelong disability and disfigurement and should be addressed as soon as the patient's condition stabilizes. It is essential to diagnose and manage these problems effectively in the emergency setting and then to make prompt direct referral to an appropriate specialist when the patient's condition permits.

Oral hygiene for the severely handicapped: clinical evaluation of the University of Mississippi dental care system.

The study reported here was a clinical evaluation of an automatic toothbrushing device for persons with severe handicapping conditions. This device, the University of Mississippi dental care system, is designed for patients who are unable to control their arms and hands. The effectiveness of this device was compared to routine (ordinary, manual) regimens of oral hygiene through use of gingival (Loe-Silness) and plaque (Turesky) indexes (GIs, PIs). Plaque indexes for patients under routine care averaged 2.11; PIs for patients under the dental care system averaged 1.47. Based on Ebbutt's extra period changeover design model, the t-test for difference in plaque scores is significant (P less than .001). The results indicate that the University of Mississippi dental care system improves the patients' ability to independently control plaque.

Microleakage of two new combined primer/adhesive resin systems.

In vitro microleakage of two new combined primer/adhesive systems utilizing the all etch technique (enamel and dentin etch) with the hybrid composite resin TPH is reported. These new combined primer/adhesive systems were compared to the Optibond FL system, which consists of a separate primer and adhesive. Forty Class V preparations were cut on the facial surfaces at the cemento-enamel junction of bovine incisor teeth to a dimension of 2.0 mm x 3.0 mm x 2.0 mm with a 1.0 mm 45 degree incisal bevel. The enamel (incisal) and dentin (gingival) margins were scored separately. Results suggest that Prime & Bond provided an improvement in the gingival marginal seal over the other materials. There was no statistically significant difference in the sealing ability of the materials tested at the incisal margin.

Adding retentive features in the rebonding of cast metal resin-bonded prostheses.

Many methods have been used to improve retention in resin-retained fixed prostheses, such as electrolytic etching of the retainer, the labial wrap design, proximal grooves, cast pin retention, and the use of improved adhesive resins such as Panavia EX (Kuraray Co, Osaka, Japan). Insufficient retentive features often lead to debonding of resin-retained fixed prostheses. Debonded prostheses may occasionally be recemented and successfully retained by the addition of retentive features to the prosthesis and abutment teeth. When recementing a debonded prosthesis with questionable retention, additional retention may be added to the retentive wings of the prosthesis by using a Rochette retentive hole in combination with pin retention or enamel/dentinal slots in the abutment teeth.

Technique to diminish discomfort from the palatal injection.

A new technique for diminishing the discomfort of a palatal injection has been described. The technique utilizes a cotton pellet saturated with dichlorodifluoromethane spray held in contact with the tissue 5 seconds to freeze a small portion of the surface tissue. The injection needle then penetrates the frozen tissue with little discomfort to the patient.

Tensile fatigue of 4-META cement bonding three base metal alloys to enamel and comparison to other resin cements.

The tensile median fatigue limits and fracture mode of 4-META cement were evaluated after bonding Ni-Cr, Ni-Cr-Be, and Co-Cr alloys to enamel. Alloy surfaces, 6 mm in diameter, were grit blasted with 50 microns Al2O3 and cemented to etched bovine enamel under a 2 kg load. Samples were cycled in tension to failure or 10(6) cycles at 5 Hz in Ringer's solution at 37 degrees C. Two-point strategy was used to determine median fatigue limits (S50). Fracture modes were evaluated by SEM on samples failing before 10(6) cycles. Results indicated differences between all sample groups where S50 (Ni-Cr-Be) > S50 (Co-Cr) > S50 (Ni-Cr). Failure analysis revealed mixed cohesive fractures near both interfaces with small areas of delamination within the cement. Comparison to reported median fatigue limits of two commercially available cements were discussed.

The reduction of phenytoin-induced gingival overgrowth in a severely disabled patient: a case report.

Gingival overgrowth frequently occurs in patients medicated with phenytoin (5,5-diphenylhydantoin) to control epileptic seizures. In a recent study, gingival overgrowth was observed in a patient in an experimental group evaluating an automatic toothbrushing system for severely disabled patients. During the evaluation period, which included an oral hygiene regimen provided by an attendant or housemate and a regimen with the Mississippi Dental Care System (MDCS), the patient's gingival overgrowth was noticeably reduced. The results of this study indicate that control of local factors with the MDCS is significantly better than the routine home care regimen, and that the phenytoin-associated gingival overgrowth in this patient was reduced by MDCS.