Showing papers in "American Journal of Dentistry in 2000"

Clinical evaluation of fiber-reinforced epoxy resin posts and cast post and cores.

Abstract: PURPOSE This retrospective study evaluated treatment outcome of cast post and core and Composipost systems after 4 yrs of clinical service. MATERIALS AND METHODS 200 patients were included in the study. They were divided in two groups of 100 endodontically treated teeth restored with a post. Group 1: Composipost systems were luted into root canal following the manufacturer's instructions. Group 2: Cast post and cores were cemented into root canal preparations with a traditional technique. The patients were recalled after 6 months, 1, 2 and 4 yrs and clinical and radiographic examinations were completed. Endodontic and prosthodontic results were recorded. RESULTS Group 1: 95% of the teeth restored with Composiposts showed clinical success; 3% of these samples were excluded for noncompliance and 2% showed endodontic failure. Group 2: Clinical success was found with 84% of teeth restored with cast post and core. 2% of these samples were excluded for noncompliance, 9% showed root fracture, 2% dislodgment of crown and 3% endodontic failure. Statistical evaluation showed significant differences between Groups 1 and 2 (P < 0.001). The results of this retrospective study indicated that the Composipost system was superior to the conventional cast post and core system after 4 yrs of clinical service.

Bonding to root canal: structural characteristics of the substrate.

Abstract: Purpose To evaluate in vitro the dentin morphology in root canals in terms of tubule orientation, density and increase in surface area after etching. Materials and methods Thirty anterior teeth were divided in 3 groups at random: the samples of Group 1 were used to study tubular morphology in SEM. Groups 2 and 3 samples were etched with 32% phosphoric acid. The teeth in Group 2 were examined by SEM without further treatment. The samples in Group 3 were treated with a bonding system and fiber posts were luted into the canal. These teeth were then processed for evaluation of hybrid layer formation and resin tags in dentin tubules. The observations were made according to location in the root dentin, tubule density was estimated, and the increase in area available for bonding after etching was calculated. Results The observations revealed variability in tubule density and orientation within different areas of any one sample. Statistically significant differences in the density of tubules were found depending on location. The dentin surface area available for bonding increased by 202% after etching in the cervical third, 156% in the middle third, and 113% in the apical third of the root dentin. Group 3 samples showed that the thickness of the hybrid layer depended on the density of tubules. In the sectors with a low density of tubules, the hybrid layer was significantly thinner than in areas with a higher density of tubules. The increase in dentin surface area might be responsible for the enhanced bond strength after acid etching, but not all areas exhibited equal responses to etching.

Retrospective study of the clinical performance of fiber posts.

Abstract: Purpose To evaluate the clinical performance of C-Posts, AEstheti Posts and AEstheti Plus Posts after a period of clinical service ranging from 1-6 yrs Materials and methods 1,304 posts were included in the study: 840 Composiposts, 215 AEstheti posts and 249 AEstheti Plus posts were placed into endodontically treated teeth Four combinations of bonding/luting materials were used The patients were recalled every 6 months and clinical and radiographic examinations were completed Endodontic and prosthodontic results were recorded Actuarial Life Table statistical analysis and Mantel-Haenszel comparison of survival curve have been performed at 95% level of confidence Results The 32% failure rate was due to two reasons: 25 posts debonded during removal of temporary restorations, and 16 teeth showed periapical lesions at the radiographic examination No statistical significant differences were found among the four groups The results of this retrospective study indicate that fiber posts in combination with bonding/luting materials can be routinely used

Adhesive luting of indirect restorations.

Abstract: Purpose To describe the potential of adhesive luting procedures with respect to (1) material characteristics and classifications, (2) film thickness, (3) overhang control, (4) bonding to different inlay materials, (5) adhesion to tooth substrates and the problem of hypersensitivities, (6) wear of luting composites, and (7) clinical performance. Materials and methods A literature review of relevant studies of various in vitro and in vivo studies enables an overview of possibilities and limitations of adhesively luted indirect restorations. Results (1) Resin-based composites are the material of choice for adhesive luting. Both material properties and wear behavior of fine particle hybrid-type resin-based composites are superior to other materials. The use of compomers is questionable due to hygroscopic expansion and possible crack formation as proven for IPS Empress caps in vitro and in vivo. (2) Recent luting cements exhibit excellent flow characteristics with mean film thicknesses ranging between 8 microm and 21 microm. The ultrasonic insertion technique is recommended for viscous luting composites or conventional restorative composites utilizing their thixotropic properties. (3) For successful overhang control, good fit of the restoration (during luting) and high radiopacity of the cement (after luting) are indispensable. Overhang control is estimated easier when the ultrasonic insertion technique is applied. (4) The pre-treatments of ceramic inlays using hydrofluoric acid or silica coating result in effective bonding; for pre-treatment of resin-based composite inlays, silica coating is promising as well. (5) Bonding to enamel and dentin is proven clinically acceptable, but it should be performed with multi-step systems providing separate primers and bonding agents producing a perfect internal seal with almost no hypersensitivities. Dual-cured multi-step bonding agents provide the most promising potential. (6) The viscosity and filler content of the resin composite used for luting does not influence the wear characteristics within the marginal luting area in vivo. However, the ultrasonic insertion technique involving high viscosity materials provides enhanced handling characteristics for luting of tooth-colored inlays. (7) Clinical results with tooth-colored inlays and veneers are promising over periods of up to 10 yrs, including use in severely destroyed teeth.

Exploring beyond methacrylates.

Abstract: PURPOSE This article focuses on the polymerization shrinkage of current dental composites as their major disadvantage and to find new routes for a solution. MATERIALS AND METHODS A brief introduction describes selected methods for the shrinkage determination as well as some principal solutions to overcome the shrinkage problem. RESULTS Siloranes, a new class of ring opening monomers, are presented as a promising resin matrix for dental composites. The synthesis of these monomers, and further consequences of the new chemistry for the formulation are discussed. Two selected silorane composites are presented with their mechanical data and their volume shrinkage.

Microscopy investigations. Techniques, results, limitations.

Abstract: This paper critically reviews current microscopy techniques that are used to image resin-dentin interfaces and more in particular to investigate the process of hybridization and resin-tag formation. A short description of the four most commonly used microscopy techniques with their necessary specimen-preparation methodology is provided along with a discussion of their possibilities, limitations and potential artifact formation. With this critical appraisal on microscopy techniques available to study adhesive interfaces, it is hoped to encourage the use of high-resolution analytical tools to further elucidate the mechanisms of bonding at the ultra-structural level. Besides ultra-morphologic characterization, more research should be devoted to study the chemical and physical properties of resin-dentin bonds. The final objective of such fundamental research should be to establish a more durable and reliable adhesive restorative technique.

Recent developments in dentin bonding.

Abstract: Hybridization of the dentin with resin by monomer interdiffusion has been identified as the basic bonding mechanism resulting in an intimate interlocking of the cured resin with the dentin. Today, growing efforts are made to simplify and shorten the bonding procedures, e.g. by combining the functions of primer and adhesive. Ultrastructural investigations using high-resolution optical technology provided exciting insight into the interactions of bonding systems and dentin. It became clear, that the maintenance or recovery of microporosities in the dentin is most important for optimal hybridization. This can be achieved by the moist bonding technique, which is mandatory in acetone-based systems. The observation that certain bonding systems are able to bond to dentin depleted from the demineralized collagen network raised the question of whether the collagen-resin interdiffusion zone really represents a prerequisite for successful bonding to dentin. The use of strongly acidic primer monomers introduced the concept of "self-etching" primers not only to dentin but also to enamel, which eliminates the necessity of a separate conditioning step. Clinical investigations are necessary to evaluate the potential of recently developed all-in-one products which combine the functions of conditioner, primer, and adhesive. With improvements in dentin bonding and the development of new resins that exhibit little or no shrinkage upon polymerization, even greater applications for adhesive technology will be found in dentistry.

New trends in dentin/enamel adhesion

Abstract: The acid-etch-technique has provided an ideal surface for bonding to enamel by using 30-40% phosphoric acid. The resulting etch pattern is characterized by the profuse formation of microporosities which allow the penetration of monomers into those porosities to form resin tags that provide micromechanical retention. Successful attempts of bonding to dentin in a similar fashion have been reported more recently. Due to the specific properties of dentin, such as its tubular structure and its intrinsic wetness, bonding to dentin has not yet reached the ideal characteristics. In spite of the existing deficiencies in dentin adhesion, the increasing demand for esthetic restorations has generated intensive research on new esthetic materials with special focus on amalgam alternatives. The bonding mechanism of recent dentin bonding agents is based on the penetration of ambiphilic molecules into acid-etched dentin to form a lacework of dentin collagen and polymerized monomers. Dentin adhesive systems that contain a multitude of different bottles of different colors and shapes belong to the past. Because clinicians are increasingly eager to try new materials, the actual tendency calls for simplification of the bonding procedure e.g. one-bottle adhesive systems and all-in-one no-bottle materials. In spite of simpler materials, a separate etching step is still needed for one-bottle systems. Nevertheless, manufacturers of these simplified one-bottle materials recommend their use to bond polyacid-modified composites (compomers) without a separate etching step. The most recent addition to the group of simplified adhesives is the all-in-one no-bottle adhesives; one of these all-in-one systems, Prompt L-Pop (ESPE) has resulted in very promising laboratory results when used on enamel. In spite of the uncertainty about the capacity of all-in-one adhesives to etch enamel adequately in vivo, scanning electron microscopy studies have resulted in an enamel-etching pattern morphologically similar to that corresponding to phosphoric acid-etched enamel. While all-in-one adhesive systems have been reported to result in very satisfactory dentin bond strengths, results from other laboratories suggest that bonding to dentin with all-in-one adhesive systems will need to be somewhat improved. Clinical studies, which are the ultimate test for the acceptance of dentin adhesives, are now underway in several centers. Six-month data showed a very good clinical performance for this ultra-simplified all-in-one adhesive system.

Clinical results and new developments of direct posterior restorations.

Abstract: PURPOSE To (1) review the literature and analyze the longevity and reasons for failure of direct resin-based composite (RBC), amalgam, and glass-ionomer cement (GIC) restorations in stress-bearing posterior cavities and (2) to assess new material developments and treatment techniques to restore these cavities. MATERIALS AND METHODS This work reviewed the dental literature predominately of the last decade for longitudinal, controlled clinical studies and retrospective cross-sectional studies. Only studies investigating the clinical performance of restorations in permanent teeth were included. Annual failure rates of direct resin-based composite, amalgam, and GIC restorations were determined and failure reasons were discussed. RESULTS Annual failure rates in posterior stress-bearing cavities were determined to be: 0-9% for direct RBC restorations, 0-7% for amalgam restorations, and 1.9-14.4% for GIC restorations. The median annual failure rate of longitudinal studies for amalgam was calculated with 1.1%, for RBCs 2.1% and for GICs 7.7%. GIC is significantly worse compared with amalgam and RBC. Main reasons for failure were secondary caries, marginal deficiencies, fracture, and wear. Longitudinal studies showed a strong trend towards a higher longevity compared with cross-sectional investigations.

Human pulpal response to direct pulp capping with an adhesive system.

Abstract: PURPOSE To evaluate clinically and microscopically the human pulp response when directly capped with an adhesive system or calcium hydroxide over short (9-12 days) and long (53-204 days) experimental periods MATERIALS AND METHODS Fifty-one sound human premolars scheduled for orthodontic extraction, had their pulp horns gently exposed with a diamond point Debris in the pulp wound was washed out with a sterile saline solution The pulps were then capped with either an adhesive system (Scotchbond Multi-Purpose Plus) or calcium hydroxide All teeth were subsequently restored with resin-based composite (Z-100) according to the manufacturer's instructions After the experimental periods, the teeth were extracted and processed for light microscopic examination RESULTS Short-term: the pulp tissue capped with SBMP-P exhibited dilated and congested blood vessels associated with a moderate inflammatory response and blanching of pulp cell nuclei Long-term: no evidence of healing and bridge formation was observed A persistent mild inflammatory pulp response was present Micro-abscesses were detected in three cases associated with bacterial infiltration Calcium hydroxide stimulated early pulp repair and dentin bridging which extended into the longest period

Effect of operator variability on dentin bond strength of two-step bonding systems.

Abstract: PURPOSE To examine the influence of operator variability on adhesion to dentin of recently developed two-step bonding systems. MATERIALS AND METHODS A self-etching primer system, Fluoro Bond/Lite-Fil II A (FB) and a one-bottle adhesive system, Single Bond/Z100 (SB) were employed. Three groups, each consisting of 15 operators, were selected from the dentists at the university (Group 1), undergraduate students (Group 2), and general practitioners (Group 3). Labial surfaces of extracted bovine teeth were ground on wet 600-grit SiC paper and then washed and dried with oil-free compressed air. These surfaces were treated according to each adhesive system's instructions and the restorative resins were condensed into a Teflon mold (2 mm height, 4 mm internal diameter) and then light-cured. The finished specimens were stored in 37 degrees C distilled water for 1 hr. These specimens were tested in a shear mode at a cross-head speed of 1.0 mm/min. The mean and standard deviation were subjected to two-way ANOVA (P < 0.05). RESULTS Significant differences in bond strength of the two adhesives were found within each operator group. A wider variation in bond strength was seen for SB compared to FB for the three different groups. Mean bond strengths for the faculty group were statistically greater than those of the other two groups, which did not differ significantly. Even though the specimen preparation was done under in vitro conditions, the large coefficients of variation indicate it may be difficult to create suitable surface conditions for optimal bonding.

Advances in light curing.

Abstract: PURPOSE: To review and connect the scientific background of light curing with clinical requirements and new technical opportunities in order to conclude the best technology for next generation light curing units. RESULTS: Three conclusions are drawn for proper light curing: (1) A minimum dose of light is needed (wavelength dependent); (2) Internal stress can be reduced by giving the sample time to flow before gel point is reached; (3) An upper intensity limit has to be respected to limit temperature increase as well as light intensity dependent deactivation of activated photoinitiators. These conclusions can best be realized by using the softstart approach. A comparison of different light generation technologies shows that LEDs are most likely to shape the next generations of curing lights. Due to their superior power conversion rate as well as to their optimum spectral emission small and handy devices can be realized that work battery-powered and totally silent. The benefits for the dentist are improved reliability, handling, and hygiene.

Development and laboratory evaluation of a new toothbrush with a novel brush head design.

Abstract: Despite many developments in manual toothbrush design, plaque removal at the back of the mouth and at approximal surfaces remains inadequate, yet it is at these sites in particular that plaque accumulates and leads to the development of gingival disease. Improved oral hygiene can be achieved by better brushing technique and by increasing brushing time, but a change in behavior patterns is almost impossible to achieve for the majority of individuals. What is required is a brush head design that maximizes plaque removal, regardless of how the user brushes. As a result of a detailed investigation into the action of bistles during brushing, the Oral-B CrossAction toothbrush has been developed. It incorporates bristles angled at 16 degrees in a unique CrissCross design arranged along the horizontal axis of the toothbrush. Laboratory studies have demonstrated that this development significantly enhances interproximal penetration and cleaning effectiveness when compared with an identical brush head with vertical rather than angled bristles. Laboratory comparisons with more than 80 leading manual toothbrushes from around the world demonstrate a consistent, significant advantage for the new CrossAction toothbrush, both with respect to interproximal penetration and cleaning effectiveness. These results suggest that the CrossAction toothbrush has the potential to remove greater amounts of plaque, especially from the approximal surfaces, than conventional toothbrushes incorporating vertical bristles or more traditional tuft designs.

Physical properties of the dentin-enamel junction region.

Abstract: Purpose To determine the physical properties between enamel and dentin at the dentin-enamel junction (DEJ) region of natural tooth structure. Materials and methods Ultimate tensile cohesive strengths of the DEJ region of human and bovine teeth were measured using a microtensile test, and the nanohardness and Young's modulus from deep enamel to superficial dentin of human teeth were measured using a nanoindentation tester. Results The mean ultimate tensile cohesive strengths of bovine and human DEJ region were 47.7 MPa and 51.5 MPa, respectively. The nanohardness, dynamic hardness and Young's modulus of the DEJ region showed moderate values between those of enamel and dentin. Comparison of the cohesive strength of the human DEJ region with previous results of the bond strength of resin bonding systems indicate that current resin bonding systems might reproduce the biological adhesion of enamel to dentin in terms of the tensile strength. Moreover, the indentation properties of the DEJ region showed higher values than those of the underlying dentin or of resin impregnated dentin.

Use of one-bottle adhesive as an intermediate bonding layer to reduce sealant microleakage on saliva-contaminated enamel.

Abstract: Dept. Orthodontics and Pediat. Dent. School of Dentistry University of Michigan, 1011 North University Avenue, Ann Arbor, MI 48109-1078

Biocompatibility of a resin-modified glass-ionomer cement applied as pulp capping in human teeth

Abstract: Purpose to evaluate the human pulp response following pulp capping with calcium hydroxide (CH, Group 1), and the resin-modified glass-ionomer Vitrebond (VIT, Group 2). Materials and methods Intact teeth with no cavity preparation were used as control Group (ICG, Group 3). Buccal Class V cavities were prepared in 34 sound human premolars. After exposing the pulps, the pulp capping materials were applied and the cavities were filled using Clearfil Liner Bond 2 bonding agent and Z100 resin-based composite. The teeth were extracted after 5, 30, and from 120 to 300 days, fixed in 10% buffered formalin solution, and prepared according to routine histological techniques. 6-microm sections were stained with hematoxylin and eosin, Masson's trichrome, or Brown & Brenn technique for bacterial observation. Results At 5 days, CH caused a large zone of coagulation necrosis. The mononuclear inflammatory reaction underneath the necrotic zone was slight to moderate. VIT caused a moderate to intense inflammatory pulp response with a large necrotic zone. A number of congested venules associated with plasma extravasation and neutrophilic infiltration was observed. Over time, only CH allowed pulp repair and complete dentin bridging around the pulp exposure site. VIT components displaced into the pulp tissue triggered a persistent inflammatory reaction which appeared to be associated with a lack of dentin bridge formation. After 30 days a few histological sections showed a number of bacteria on the lateral dentin walls. In these samples the pulp response was similar to those samples with no microleakage. VIT was more irritating to pulp tissue than CH, which allowed pulp repair associated with dentin bridge formation. These results suggested that VIT is not an appropriate dental material to be used in direct pulp capping for mechanically exposed human pulps.

Self-contamination of deep dentin by dentin fluid.

Abstract: PURPOSE: To compare, with the use of a resin replica technique, surface features of deep, acid-conditioned dentin from vital human molars that were anesthetized with an anesthetic: Group 1: without a vasoconstrictor (Mepivacaine 3%), and Group 2: containing a vasoconstrictor (Lidocaine 2% with 1:80,000 epinephrine). MATERIALS AND METHODS: 10 Class I cavities with dentin caries were included in each group. Following complete caries removal, a total-etch technique was performed with 32% phosphoric acid (Uni-Etch) for 15 s. After rinsing, each cavity was air-dried for 1 s, then a slow setting vinyl polysiloxane (President) impression was taken. As a control, impressions were taken from three additional cavities in teeth that were anesthetized with Mepivacaine 3% but not acid etched. A TEM-grade epoxy resin was used to prepare replicas from the impressions. Polymerized replicas were coated with gold and examined with a scanning electron microscope. RESULTS: In Group 1, fluid was visible leaving tubular orifices in all replicas. In addition, three were covered with a smooth, amorphous film that was different from the granular appearance of the smear layer in the control cavities. In Group 2, patent tubular orifices without fluid were observed in all specimens. Odontoblast process-like structures were seen from some dentin tubules.

Comparative microtensile bond strength and SEM analysis of bonding to wet and dry dentin.

Abstract: PURPOSE: To compare bond strengths of resins to acid-etched wet vs. dry dentin. MATERIALS AND METHODS: Human third molars were bonded with One-Step (OS), Single Bond (SB) or Clearfil PhotoBond (PB) under control moist or air-dried (5 s air blast) conditions. Tensile bond strengths were tested using the microtensile bond testing method. Scanning electron microscopy was done to evaluate the quality and thickness of the hybrid layers following polishing and acid plus NaOCl-challenge. RESULTS: The tensile bond strengths of OS, SB and PB were significantly (P < 0.01) lower (8-19 MPa) to air-dried dentin than to moist dentin (39-50 MPa). No hybrid layers were seen in the air-dried specimens bonded with OS or SB, while relatively thin hybrid layers were produced by PB. In contrast, moist dentin produced high bond strengths with all bonding systems and created thicker, acid/NaOCl-resistant hybrid layers. These results support the predictions of a previously published morphologic model and offer a morphologic explanation for the differences in bond strengths between wet vs. dry bonds.

Fluoride release/uptake from newer glass-ionomer cements used with the ART approach.

Abstract: Purpose To determine the fluoride ion release/uptake of two conventional glass-ionomer cements (GICs) manufactured for use with the ART approach (Fuji IX GP, Ketac-Molar), as compared with that of a resin-modified GIC (Fuji II LC). Materials and methods 15 specimens of each material were prepared and placed in vials with artificial saliva and stored at 37 degrees C. The solution was replaced weekly for 6 wks, and the fluoride ions released were measured in ppm each week. After 6 wks, the 15 specimens of each material were divided into three equal groups and placed into three fluoride recharging agents (1.23% APF gel, 1.1% neutral NaF and 0.001% CaF2) for 4 min at 23 degrees C. Fluoride ion measurements of the recharged specimens were carried out at 1 day, 2 days, then weekly for another 6 wks. Results All freshly-mixed specimens showed the highest fluoride ion release after 1 week, then the release rates dropped quickly to become largely stabilized after 3 wks. After one 4-min exposure to APF gel the initial fluoride ion release increased significantly for all materials. The highest rates were during the first day, but then dropped very quickly to again become largely stabilized after usually 3 wks. Exposure to NaF and CaF2 did not usually result in significantly sustained fluoride ion release by any material. The order of release/uptake for all three agents was Fuji II LC > Fuji IX GP > Ketac-Molar. The mechanism of fluoride ion release after the application of different fluoride recharging agents is not clear. It may occur partly by washout of recharge agents that are retained in the pores and cracks of the restorative materials, for APF gel is viscous and difficult to wash off completely with deionized water; by erosion of surfaces by low pH agents, or by the subsequent release of fluoride ions from within the cement matrix.

Microleakage of Class II resin-based composite restorations with flowable composite in the proximal box.

Abstract: PURPOSE To compare microleakage of Class II hybrid resin-based composite (RBC) restorations with and without low viscosity (flowable) RBC in the proximal box. MATERIALS AND METHODS Conservative Class II cavity preparations were made in 50 extracted premolars randomly assigned to five groups (n = 10). OptiBond FL dentin bonding agent, and Prodigy hybrid RBC were used to restore all cavity preparations. Preparations in four of the five groups were restored with flowable RBC as the initial increment in the proximal box. The four flowable RBCs tested were: AEliteFlo, Revolution, UltraSeal XT and Flow-It. In the control group, the entire preparation was restored only with hybrid RBC. Specimens were stored in water at 37 degrees C for 24 hrs after restoration, thermocycled 1,000x, immersed in 2% basic fuchsin, sectioned and evaluated for microleakage. Microleakage was scored on a 0-4 scale. RESULTS Non-parametric Kruskal-Wallis one-way ANOVA followed by Wilcoxon signed ranks test was used for statistical analysis. The use of any of the four flowable RBCs tested did not influence microleakage significantly (P > 0.05) in Class II RBC restorations.

Clinical evidence for the lack of triclosan accumulation from daily use in dentifrices.

Abstract: Purpose To demonstrate through clinical pharmacokinetic studies that triclosan does not accumulate in blood or plasma in human subjects who regularly use triclosan-containing dentifrice. Materials and methods Three clinical pharmacokinetic studies were conducted to assess the blood or plasma levels of triclosan following toothbrushing with dentifrice formulations containing triclosan. In Study 1, both a single-dose and a multiple-dose phase were conducted. In the single-dose phase, subjects brushed one time with 1.25 g dentifrice containing 0.3% triclosan (3.75 mg triclosan dose) and ingested all of the dentifrice. Blood samples were collected at multiple time points from pre-dose to 72 hrs post-dose and analyzed for total triclosan levels. In the multiple-dose phase, these same subjects brushed three times daily as in the single-dose phase. This pattern was followed for 12 consecutive days. Blood samples were taken for triclosan analysis at multiple time points up to 48 hrs after the first dose of day 12. Study 2 was a parallel, open-labeled clinical study to compare triclosan blood levels from twice daily brushing with 1 gm of dentifrice containing 0.2% triclosan to twice daily ingestion of 20 ml of a 0.01% triclosan aqueous solution over a period of 21 days. Blood samples were taken for triclosan analysis at baseline and at 4 hrs after the morning dose on days 7, 14, and 21. Study 3 was a parallel, double-blind, 12-wk brushing study with dentifrice containing 0.2% triclosan or a matching placebo. Blood samples were taken for triclosan analysis at baseline and at 3 and 12 wks at 4 hrs after the morning dose. Results In the single-dose study, Triclosan was absorbed into the systemic circulation with a T(1/2) of the terminal plasma concentration ranging between 6-63 hrs. The mean AUC(0-inf) after a single dose was found to be 2,809 ng x hr/ml. After 12 days of three times daily toothbrushing and ingestion of the dental slurry, the mean triclosan plasma concentration was 352 ng/ml in the steady state period, and the mean AUC in a 24-hr period (AUC24) was found to be 8,460 ng x hr/ml. This AUC24 was normalized for the number of brushings for comparison to the AUC(0-inf) after a single brushing. There was no significant (P = 0.93) difference between these AUC values suggesting a complete elimination of daily triclosan dose and no increase in the triclosan level during repeated brushing/ingestion. In the two other dentifrice studies, the triclosan blood concentration appeared to reach a steady state level by day 7 and was maintained at the steady state level (14 to 21 ng/ml) for up to 12 wks. These results support the conclusion that the elimination of a daily triclosan dose is complete and no accumulation of triclosan was observed even after three times daily toothbrushing with 1.25 g dentifrice containing 0.3% triclosan and full ingestion of the dentifrice.

Composite surfaces after finishing and polishing techniques.

Abstract: Purpose To evaluate the effect of finishing and polishing techniques on surface roughness of resin-based composites (RBCs). Materials and methods Forty specimens of each material were cured under Mylar strips and immersed in artificial saliva for 1 wk. Samples were tested with a profilometer to obtain baseline average surface roughness (Ra). Specimens of both RBCs were then finished and polished according to four techniques: (1) Sof-Lex disks; (2) Sof-Lex disks followed by Prisma Gloss; (3) Enhance points; (4) Enhance points followed by Prisma Gloss application. New readings of the roughness pattern were carried out and the difference of post-polishing and baseline values were analyzed. Results ANOVA test (alpha = 0.05) did not show differences between materials (P = 0.9393) nor interaction effects (P = 0.3094), but significant difference among the finishing/polishing techniques were detected (P = 0.0157). Tukey's test showed that the smoothest surface was obtained when the specimens were treated by Sof-Lex followed by Prisma Gloss polishing paste; and the worst results were obtained after using Enhance points alone.

Pulp response to direct capping with an adhesive system.

Abstract: Purpose To evaluate the pulp response following direct pulp capping with an adhesive system (Prime & Bond 2.0 - PB 2.0) and a zinc-oxide eugenol cement (ZOE) on pulp exposures in rat molar teeth. Materials and methods Forty-eight Class I cavities were prepared on the occlusal surface of molar teeth of rats (Rattus Norvegicus, Holtzman). Pulp exposures performed on the cavity floor were capped either with the adhesive system P&B 2.0 or ZOE. After 7, 15, 30, and 60 days, the specimens were processed through H & E and Brown & Brenn staining techniques. Results Both pulp capping materials allowed pulp repair, characterized by reorganization of a new odontoblast cell layer underlying the dentin bridge formation. However, P&B 2.0 promoted a large zone of cell-rich fibrodentin matrix deposition between the pulp capping material and the dentin bridge, which was deposited far from the pulp exposure site. On the other hand, pulps capped with ZOE showed dentin bridging immediately subjacent to the pulp capping material. In those samples in which microleakage occurred between dental material and cavity walls there was a persistent inflammatory reaction and lack of complete pulp repair.

Stress reduction in resin-based composites cured with a two-step light-curing unit.

Abstract: PURPOSE To examine the stress reduction of different resin-based composites, cured with a two-step polymerization unit (Elipar Highlight) by means of a photoelastic investigation. MATERIALS AND METHODS For each material (Pertac II, Tetric Ceram, Charisma F, Solitaire, Dyract, Dyract AP, Definite), a minimum of 10 resin samples, embedded in acrylic-glass plates, were polymerized using a standard polymerization process of 700 mW/cm for 40 s. Another 10 samples were polymerized with a light output of 150 mW/cm2 for 10 s and then with a light output of 700 mW/cm2 for 30 s. RESULTS For Pertac II the reduction of polymerization stress in the two-step-mode was 15.5%, for Tetric Ceram 14.5%, for Solitaire 8.1%, for Dyract AP 6.5% and for Definite 4.7%. These differences in polymerization stress between the standard and two-step-polymerization mode were statistically significant (P < 0.01, Wilcoxon test). No statistically significant differences in polymerization stress could be found for Charisma F and Dyract.

Rapid general dental erosion by gas-chlorinated swimming pool water. Review of the literature and case report.

Abstract: Several reports indicate an increased prevalence of dental erosion among intensive swimmers due to low pH gas-chlorinated pool water. Contrary to other extrinsic factors which induce erosion located on the facial aspect, low pH pool water results in general dental erosion. Additionally, a case report is presented which describes the very rapid occurrence of excessive general dental erosion of a competitive swimmer due to gas-chlorinated pool water within 27 days. The observation of several authors as well as this case underscore the significance of a regular pH monitoring of chlorinated swimming pool water. The high incidence indicates that dental erosion due to frequent swimming is of considerable diagnostic and therapeutic significance. Furthermore, it is recommended to fluoridate the teeth of intensive swimmers regularly to prevent dental erosion.

Role of hybridization on marginal leakage and bond strength.

Abstract: PURPOSE To evaluate whether the hybrid layer significantly contributes to the seal of adhesive Class V restorations placed in vivo and to the bond strength obtained in vitro. MATERIALS AND METHODS 20 periodontally severely compromised anterior teeth were selected for the leakage study. In each tooth, one round 3 mm wide V-shaped cavity with a maximum depth of 2 mm was prepared on the labial surface crossing the cementum-enamel junction. The sample teeth were randomly divided into two groups of ten samples each: in Group 1, Scotchbond Multi-Purpose Plus was applied in combination with Z-100 following the manufacturer's instructions. In Group 2 the bonding procedure was the same as in Group 1, except that after the phosphoric acid treatment, the cavities were treated with 5% NaOCl for 2 min. Following a period of clinical service of 60-90 days, the teeth were extracted and processed for the leakage test. RESULTS At the enamel site, 30% of the samples of Group 1 and 70% of the samples of Group 2 showed dye penetration. At the dentin site, 50% of the samples of Group 1 showed leakage, while all the samples of Group 2 were severely infiltrated. Statistically significant differences between the groups both for the enamel sites (P < 0.05) and for dentin-cementum sites (P < 0.001) were found. Bond strength tests were performed on 2 mm thick dentin slides of tapered Class I cavities (n = 10 in each group). The mean bond strength value obtained from cavities treated without NaOCl was 15.23 (+/-1.40) MPa and with NaOCl treatment 20.52 (+/-1.70) MPa. Statistical analysis showed significant differences (P < 0.05) between the two groups. No hybrid layer was detected on the NaOCl-treated samples by scanning electron microscopy.

Removal of fiber posts from endodontically treated teeth.

Abstract: The removal of posts from endodontically treated teeth can be a major obstacle in the retreatment of teeth that have recurrent pathology, often leading to extraction of a tooth that could have been saved with endodontic retreatment. The use of a fiber post offers the advantages of a suitable elastic modulus and good bonding between post and cement, but also the advantage of easy removal, if so indicated by clinical findings. A special removal kit for fiber posts has been developed, and its use is illustrated, and described. The removal procedure can be completed in a very short time, usually less than 5 min. The tooth can then be restored with the same type and size of fiber post as was in the tooth prior to removal. Removal kits are found to be for single use only.

Cavity wall adaptation of resin-based composites lined with flowable composites.

Abstract: PURPOSE To compare the adhesion of a flowable resin-based composite (RBC) vs. a condensable RBC to tooth structure using scanning electron microscopy (SEM). MATERIALS AND METHODS Fifteen recently extracted human teeth were prepared for Class I restorations and equally divided into three groups. Group 1 was filled with Heliomolar bonded with Syntac Single Component. Group 2 was lined with Flow-It in addition to ALERT condensable RBC bonded with Bond-1 Primer/Adhesive. Group 3 was filled with ALERT bonded with Bond-1 Primer/Adhesive. All teeth were thermocycled, sectioned and evaluated for gap formation with the SEM. RESULTS SEM at x15 demonstrated that restorations with the flowable RBC at the tooth/restoration interface showed no evidence of marginal gaps between the RBC material or at the underlying tooth structure. A significant difference (P < 0.05) in wall adaptation was found between Groups 2 and 3.

Effect of stepped light exposure on the volumetric polymerization shrinkage and bulk modulus of dental composites and an unfilled resin.

Abstract: PURPOSE To compare the volumetric polymerization shrinkage and dynamic bulk modulus of five resins and an experimental unfilled resin polymerized with a stepped power light and with a conventional one step curing light. MATERIALS AND METHODS Parallel sided glass rings 5 mm in diameter and 2 mm high were etched for 5 min with hydrofluoric acid and silanated. The density and volume of the rings were calculated before they were filled with either SureFil, AEliteflo, Pertac II, Z100, or an experimental unfilled resin. When cured, the resin was bonded to the glass ring which produced a mold with a configuration C-factor of approximately 0.8. The resin was cured for 40 s on each side using either a one step curing light or a stepped power curing light. After curing, the specimens were weighed in air and in water to calculate their final density and volumetric shrinkage. Ten samples were made using each light system and for each resin (total of 100 samples). The bulk modulus was determined for each resin using an ultrasonic method, and the percentage filler contents were determined by thermogravimetric analysis. RESULTS The mean +/- SD volumetric polymerization shrinkage values ranged from 3.10 +/- 1.19% for SureFil using the one step light to 12.35 +/- 1.38% for the unfilled resin using the stepped power curing light. Student-Newman-Keuls post hoc test separated the 10 different materials into three significant groups at P= 0.05. The unfilled resin exhibited the highest volumetric shrinkage followed by the flowable composite (AEliteflo). For all materials tested, there was no significant difference in the volumetric shrinkage values when the resin was cured with the one step or the stepped power curing light. There was no significant difference in the volumetric shrinkage values for the hybrid composites (Pertac II, Z100, and SureFil). The volumetric shrinkage values were highly sensitive to filler weight (P < 0.001). Except for Z100, there was no difference in the specific gravity values and velocities of the longitudinal and shear waves and bulk modulus when the one step and stepped power curing lights were used. The bulk modulus values ranged from 6.30 +/- 0.19 GPa for unfilled resin, to 17.10 +/- 1.09 GPa for Z100. Curing with the one step or the stepped curing light had no significant effect on the modulus values for any resin with the exception of Z100, P = 0.05. The bulk modulus values were highly sensitive to filler weight, and higher modulus values were associated with increased filler weight (P < 0.001). There was no significant difference between the bulk modulus of Pertac II and SureFil (P = 0.05).

Effect of mouthwash and accelerated aging on the color stability of esthetic restorative materials.

Abstract: PURPOSE To evaluate the color stability of esthetic restorative materials after immersion in mouthwashes and accelerated aging. MATERIALS AND METHODS Compomers and resin-based composites (RBC) were measured at baseline and repeatedly after immersion in three kinds of mouthwash (Listerine, Peridex, Rembrandt Age Defying) for 24 hrs and 7 days, and after aging for 150 kJ/m2. Color was measured according to CIE L*a*b* color scale on a reflection spectrophotometer. RESULTS After immersion for 7 days, the mouthwash groups did not produce significantly higher color changes than the distilled water group, except with some mouthwashes used with Tetric-Ceram. After immersion for 7 days and aging for 150 kJ/m2, the mouthwash groups did not produce significantly higher color changes than the distilled water group. Aging in weathering chamber produced color change (deltaE*) of 1.1-3.9, which was mainly influenced by the material. With some exceptions, the color changes from immersion of the RBCs and compomers in mouthwashes were not perceptible (deltaE*<3.3).