Clinical performance of a bioactive dental luting cement--a prospective clinical pilot study.

OBJECTIVE: To conduct a pilot study determining the clinical efficacy ofa new bioactive dental cement (Ceramir Crown & Bridge) for permanent cementation in fixed prosthodontics. The composition is a hybrid comprised of a calcium aluminate and a glass ionomer. METHODS: This study examined the performance of Ceramir Crown & Bridge after cementation of high-gold alloy and porcelain-fused-to-metal (PFM) single crowns and bridges. A total of 38 crowns and bridge abutments were cemented in 17 patients; 31 were on vital, seven on non-vital teeth. Six were bridges with 14 abutment teeth (12 vital/two non-vital). One fixed splint comprising two abutment teeth was also included in the study. Preparation parameters were recorded, as well as working time, setting time, seating characteristics, and ease of cement removal. Baseline data were collected on dispensing, mixing, and handling of the cement; gingival inflammation index (GI), and a visual analog scale (VAS) and categorical assessment measured pre-cementation sensitivity. Post-cementation parameters were post-cementation sensitivity, categorical and VAS, gingival tissue reaction, marginal integrity, and discoloration. A one-week post-op telephone call recorded subjectively the patients' comfort level. RESULTS: Working time (two minutes) and setting time (four minutes) were well within normal limits. Cement removal was determined to be very easy. Thirteen of 17 patients reported no post-cementation sensitivity after seven days; four reported a low-grade sensitivity. All 17 patients were seen for recall examinations at 30 days and six months. Of the four sensitivity cases, three were related to hyperocclusion, which disappeared spontaneously after adjustment. One case was due to post-cementation pressure from a three-unit bridge, which disappeared without intervention. After six months, no retentive failures were recorded, no sensitivity was subjectively reported, marginal integrity scored 38 alphas, one tooth had a 1 and two teeth a 0.5 GI score. Average VAS score for tooth sensitivity decreased from 7.63 mm at baseline to 0.44 mm at the six-month recall. Average GI score for gingival inflammation decreased from 0.56 at baseline to 0.11 at the six-month recall. CONCLUSION: After six months, Ceramir Crown & Bridge performed favorably as a luting agent for permanent cementation.

One year clinical performance and post-operative sensitivity of a bioactive dental luting cement--a prospective clinical study.

A one-year clinical study was performed on the efficacy of a bioactive dental cement (Ceramir C&B) with calcium aluminate and glass ionomer components. The study was performed on 38 crown and bridge abutments in 17 patients. Preparation parameters were recorded, as well as working-times, setting-times, and other handling characteristics. Baseline data were also recorded for gingival inflammation (GI) and pre-cementation sensitivity. Post-cementation parameters included sensitivity, gingival tissue reactions, marginal integrity and discolorations. All patients were seen for recall examinations at 30 days, and 6 months. For sixteen patients one-year recall data were collected on retention and subjective sensitivity. Fifteen subjects were available for one year clinical examinations. Three independent examiners found the working and setting time of the cement to be well within expected limits and that cement removal was easy. Four patients reported low-grades of immediate post-cementation sensitivity, however, this disappeared after an occlusal adjustment or without intervention within one month. At 12 months no retentive failures were recorded and no subjective sensitivity reported. All crowns were rated in the "Excellent" quality category for marginal integrity. Both GI-scores and scores for tooth sensitivity decreased during the course of the study. One year recall data yielded no incidence of secondary caries and no visible marginal discoloration. The new cement was thus found to perform favorably as a luting agent for permanent cementation.

The art and science of abrasive finishing and polishing in restorative dentistry.

Effective use of rotary cutting burs and bonded, coated, and loose abrasives can greatly simplify and improve the effectiveness of finishing and polishing procedures. Fluted carbide finishing burs appear to be the optimal rotary contouring devices for posterior composite resins. Finishing diamonds are preferred for gross finishing of adjusted porcelain. Coated abrasive discs and strips provide unique interproximal and incisal access and are preferred for finishing and polishing of microfil resins. Rubberized bonded abrasives have evolved to provide a greater range of finishing and polishing action on composite resin and for polishing porcelain. A wide selection of aluminum oxide and diamond polishing pastes, together with highly effective felt and foam application devices, are now available to polish composite and porcelain to an enamel-like appearance. Aluminum oxide composite polishing pastes are highly effective and strongly recommended for use on highly filled hybrid composites but have limited utility on microfil resins, with use of extrafine (0.3-mu) pastes clearly contraindicated.

Adherence of "stuck" restorations to demineralized dentin following use of experimental primers.

PURPOSE: This in vivo study histopathologically evaluated the biocompatibility of four self-conditioning dentinal primer formulas in four bonding systems and evaluated the pulpal responses of the self-conditioning dentinal bonding systems for Class V tooth preparations in primates. MATERIAL AND METHODS: The basic formula consisted of proprietary carboxylic diacid monomer, dipentaerythritol pentaacrylate phosphoric acid ester, acetone, and ethanol that was used alone or mixed with other commercial priming agents. After application of primers, Prisma Universal Bond 3 was selected to restore the cavity preparations. RESULTS: All systems were judged histopathologically biocompatible. "Stuck" restorations that were resistant to acid demineralization necessary for processing of histologic slides, occurred more frequently with intact smear layers and increasing use of dehydrating agents. CONCLUSIONS: Tests should be performed to determine whether "stuck" restorations in in vivo studies that maintain dentin-pulpal relationships can support in vitro shear bond strength tests.

Retentive properties and film thickness of 18 luting agents and systems.

In the past, retention of castings depended on mechanical interlocking or adhesion to enamel and dentin by means of chelation in the case of some cements. Some new luting agents adhere to metal and tooth structure. The era of bonded casts for crowns and bridges has arrived through a combination of dentin primers and luting agents that bond to enamel, dentin, and precious and nonprecious metals. For a few systems, the retentive forces (in an otherwise nonretentive experimental design) more often than not exceeded tooth strength.

Three composite finishing systems: a multisite in vitro evaluation.

Selection of appropriate finishing and polishing devices is critical to the optimal appearance and longevity of composite resin restoratives. This report compares the effectiveness of three specific finishing and polishing systems when used to prepare the surfaces of composite restorative materials provided by the respective manufacturers. Profilometer surface roughness analyses were conducted at two separate laboratories to cross-correlate numerical smoothness data in this study. Statistically significant differences in mean surface roughness were found between various finishing system/composite resin pairings. Surprisingly, a hybrid composite resin finished and polished with its respective finishing/polishing system gave a significantly smoother surface than a microfill composite surface prepared with its corresponding sequentially coated abrasive disc system. This finding was corroborated at a second site using a separate methodology for profilometer analysis.

Bond strength, microleakage, and scanning electron microscopy examination of the Prisma Universal Bond 2 adhesive system.

Dentin shear bond strength and marginal microleakage of a new primer/adhesive system were evaluated in this study and compared to Tenure Solution, Gluma, XR Primer/XR Bond, and Scotchbond 2. In addition, scanning electron microscopy examinations were conducted to evaluate the effect of the new primer on the smear layer, determine the film thickness of the primer/adhesive, and examine the resindentin interface of restorations placed with the new system.

Use of a visible light cured elastomeric resin to stabilize cervical matrix in restoration of Class V erosion lesion.

Effective moisture control and gingival retraction are essential prerequisites for success in the restoration of Class V bonded restorations. Various techniques exist for cervical isolation and moisture control in Class V restorations. This case report details a modified technique in which a visible light cured elastomeric resin was utilized to stabilize a cervical matrix in restoration of a Class V erosion lesion. The resultant customized matrix provides effective isolation, moisture control, and gingival retraction when used in conjunction with Class V restorations.

In vitro evaluation of two new dentin adhesive systems.

Two new experimental dentin adhesive systems were evaluated to determine in vitro dentin bond strengths and marginal microleakage. Scanning electron microscopy examinations were also conducted on one of the systems that was designed to modify the smear layer. Mean shear bond strength for the two experimental systems were 6.77 +/- 1.94 MPa and 18.73 +/- 2.4 MPa. Marginal microleakage from the enamel margin was not observed and the experimental primer system limited leakage from the dentin margins. The SEM examinations showed that the primer did not significantly alter the smear layer on the prepared dentin surface.

Full-field modeling of the longitudinal electro-optic probe.

Optical polarization changes and mode coupling due to spatially varying anisotropic perturbations in caused by electro-optic, acousto-optic, and other effects have been widely studied for both plane-wave and fiber mode propagation. A new optical S-parameter analysis of these effects, applicable to arbitrary optical field distributions, is presented. It is applied to evaluating the performance of the longitudinal electro-optic probe used for noninva-sively examining GaAs integrated circuits. Error in probe measurements of circuit voltage distributions can be characterized by considering the probe as a scanned electro-optic spatial filter.

A collagen-alkaline phosphatase conjugate membrane: enzymatic kinetics in-vitro stability.

Collagen-alkaline phosphatase membranes have been prepared, and their enzymatic kinetics and in-vitro stability analyzed. Collagen-alkaline phosphatase dispersions were prepared by complexation in aqueous alkaline solution and cast into membranes by controlled dehydration. These membranes were then crosslinked in glutaraldehyde solution, washed thoroughly, and dried. Crosslinking in glutaraldehyde confers increased stability of catalytic activity to these collagen-enzyme membranes, especially when compared to uncrosslinked collagen-alkaline phosphatase membranes assayed in a similar fashion. Crosslinking in glutaraldehyde also appears to inhibit gross leaching of the soluble enzyme from the carrier matrix. Apparent intrinsic kinetic properties of the collagen-alkaline phosphatase conjugate were analyzed in membranes of various thickness in order to determine the effect of internal diffusion resistances on the kinetics of the immobilized enzyme. The apparent Michaelis constant of the immobilized enzyme decreased as a function of decreasing membrane thickness, reaching an observed apparent Michaelis constant of 1.6mM at a membrane thickness of 0.2 mm. Extrapolation of the apparent Michaelis constant to zero membrane thickness, using a linear plot of the natural logarithm of the apparent Michaelis constant versus membrane thickness, allowed estimation of the true Michaelis constant of the immobilized enzyme. The estimated value for the true Michaelis constant of the collagen-alkaline phosphatase complex was 0.7mM. This value agrees closely with reported values for several purified mammalian alkaline phosphatase. The apparent Michaelis constant for the 0.2mm collagen-enzyme membrane agrees closely with the Michaelis constant reported for an alkaline phosphate purified from chondrocyte matrix vesicles. The intrinsic maximum reaction velocity (V(m)) of the collagen-enzyme complex was estimated b plotting the observed reaction rate as a function of decreasing membrane thickness and extrapolating such plots, at various substrate concentrations, to the limiting case of zero membrane thickness. The maximum reaction velocity was obtained by the common intercept of these plots as they approached zero membrane thickness.

L-asparaginase bound to collagen membranes: effect of glutaraldehyde crosslinking on stabilization of catalytic activity.

Reconstituted bovine collagen has been used extensively in our laboratory as a carrier for immobilized E. coli L-asparaginase. The activity and catalytic stability of these collagen-asparaginase membranes can be altered substantially by conditions used in membrane crosslinking with glutaraldehyde. As the concentration of glutaraldehyde used in tanning is increased, the initial specific activity of collagen-asparaginase membranes decreased asymptotically to a limiting value. Similar results occurred when membranes were subjected to increasing time periods of tanning at a constant glutaraldehyde concentration. These observations point to a time-concentration relationship for glutaraldehyde tanning and its effect on the specific activity of collagen-asparaginase membranes. Specific activities of membranes tanned a glutaraldehyde concentrations of 5% or higher appear to be very stable over long periods of alternate storage and assay. This result, however, is not observed with membranes tanned at glutaraldehyde concentrations lower than 5% for short periods of time (approximately 30 sec to 1 min). It is not clear whether the instability of membranes tanned at lower concentrations of glutaraldehyde or shorter intervals of tanning is due to enzyme elution from the membrane or denaturation of the bound enzyme.

Preliminary studies with L-asparaginase bound to implantable bovine collagen heterografts: a potential long-term, sustained dosage, antitumor enzyme therapy system.

In this study, L-Asparaginase has been bound to collagen heterografts derived from carotid bovine arteries. The immobilization procedure utilizes both non-covalent and covalent interactions to fix the enzyme. Binding of the enzyme to the graft material was shown to the pH dependent, with optimum binding occurring at pH 6.0 and pH 8.5. Amidohydrolysis by the bound enzyme exhibited zero-order kinetic behavior at substrate saturating conditions. Total apparent asparaginase activity expressed by the grafts as a function of the number of repeated in vitro assay trials demonstrated that over a span of 3 months of intermittent storage and use, the enzyme-grafts retained as much as 62% of their initial activities. Implantation of 4 asparaginase-collagen grafts in various locations of the thoracic and abdominal aorta resulting in prolonged reductions of plasma asparagine levels in 3 of the 4 implants. Presence of plasma asparaginase was checked in one of the four implants and determined to be less than 2 X 10(-4) I.U./ml. Removal of grafts from 3 of the 4 animal subjects showed reductions in the apparent asparaginase activity expressed by the grafts of 7 to 70 percent after in vivo contact times which varied from 6 to 15 days.