Evaluating a microfill posterior composite resin. A five-year study.

This study evaluates a pre-polymerized microfill composite resin. Results show this particular resin is resistant to generalized wear in conservative restorations.     

Prepolymerization of Gluma 4 sealer: effect on bonding

This study evaluated the effect on microleakage of placing a composite resin over either cured or uncured Gluma 4 sealer. Class V preparations were placed at the cemento-enamel junction of extracted human molars. Herculite XR was used to restore cavities that had been pretreated with Gluma bonding system with the sealer being either uncured or cured prior to placing the restorative resin. The restored teeth were thermally stressed for 100 temperature cycles and placed in a dye solution for 24 hours. Microleakage was measured under a microscope at x50 magnification. Under the experimental conditions, leakage was significantly reduced when the sealer was pre-polymerized and an incremental composite resin placement technique was utilized.     

Push-out strength and SEM evaluation of resin composite bonded to internal cervical dentin

Abstract The bond strength of a resin composite used with a dual-cured dentin bonding system to internal cervical bovine dentin was evaluated using a direct or indirect placement technique. Teeth were sectioned transversely to produce 4 mm-thick specimens. The root canals were enlarged to a standardized taper, treated with a dentin bonding system, and filled with a lightcured resin composite using either direct, incremental composite placement or indirect composite placement of a pre-polymerized composite inlay. The debond stress of indirectly placed restorations using a composite inlay was 8.5 (SD±2.7) MPa which was significantly greater (p<0.0001) than the value of 5.0 (SD±1.9) MPa for composite placed in a conventional, incremental manner. SEM evaluation revealed the indirect placement technique demonstrated increased resin tag density and length as compared to the direct technique. Enhanced retention of resin composite to endodoutically prepared dentin treated with a dentin bonding system was obtained by using a composite inlay technique as opposed to direct, incremental buildup of the material.     

Posterior composite restorations in primary molars: an in vivo comparison of three restorative techniques

This in vivo study evaluated the clinical performance of class II restorations, in primary molars after 12 months. Three restorative techniques were used: filling the cavities in bulk; filling with three horizontal increments and placement in three horizontal increments using pre-polymerized composite inserts. The composite resin used was Prisma TP.H (Caulk-Dentsply) with the adhesive system ScotchbondMultipurpose (3M). Initially 90 class II restorations were placed in 27 patients from 8 to 10 years of age and followed-up for 12 months. After this period 55 restorations were evaluated for anatomic form, color alterations at the margins, presence of decay and marginal adaptation. The results showed that all groups presented similar rates of wear, the bulk insertion technique showed better results for marginal adaptation, color alterations of the margins and less presence of caries at occlusal margins, and that composite resin TP.H could be used in class II restorations in primary molars.     

The restoration of the anterior teeth with an eroded crown angle with combined inlays

Restoration of a front tooth with destroyed crown corner by means of filling material is ineffective, particularly so if the tooth shape is abnormal and/or dental cavity large, this impeding fixation of parapulpar rods. The author describes a combined insert prosthesis, the technique consisting in preparation and fixation of a cast metal insert in a tooth and subsequent coating of its vestibular surface with composite material. Indications for the use of this prosthesis design are defined.     

Inserts – megafillers in composite restorations: a literature review

Modern insert systems have been available on the dental market since the late 1980s. In general, two major systems can be distinguished: those with and those without preparation instruments in combination with matching standardized inserts. It is claimed that one of the advantages of insert systems is the better marginal adaptation of insert/composite restorations compared to mere composite restorations: the integration of inserts reduces the polymerization shrinkage stress and lowers the overall coefficient of thermal expansion. In vitro data indicate that adapting the insert size to the most precise fit produces a quality of marginal adaptation comparable to that of ceramic inlays. Inserts also facilitate the establishment of a proximal contact. With respect to wear, no significant differences are detected between composite and insert restorations. The bond between insert and composite is susceptible to contamination during operative procedures. Short-term clinical investigations confirm in vitro findings regarding improved marginal adaptation and increased wear resistance. Long-term controlled clinical studies are in progress, but data are not yet available. Based upon the present in vitro and in vivo data it can be concluded that the insert technology shows promising results, but further investigations regarding, for example, stability of the insert/composite bond, fracture resistance of the overall restoration, and wear behavior are necessary to predict the clinical success of this alternative restoration procedure. Received: 30 November 1999 / Accepted: 12 December 1999     

Bonding and wear characteristics of a tri-n-butylborane initiated adhesive resin filled with pre-polymerized composite particles

This study evaluated the wear characteristics and bonding to silver-palladium-copper-gold (Ag-Pd-Cu-Au) alloy of an acrylic resin that was filled with pre-polymerized composite particles and initiated with tri-n-butylborane (TBB) derivative (Bondfill). Three methyl methacrylate (MMA)-based resins (Bondfill, Super-Bond, and Multi-Bond II) and a microfilled composite restorative material (Metafil C) were assessed. Disk specimens were cast from the alloy and were air-abraded with alumina. The disks were bonded with nine bonding systems selected from two priming and three luting agents. Shear bond strengths were measured before and after thermocycling. Bond strength varied from 2.2 MPa to 28.2 MPa. Three systems based on thione primers (Metaltite and V-Primer) and TBB-initiated resins (Bondfill and Super-Bond) had the highest bond strength after thermocycling (15.9-20.4 MPa). The toothbrush-dentifrice abrasion test showed that the Metafil C material was the most wear-resistant, followed by Bondfill and Super-Bond. In conclusion, Bondfill resin is an alternative to Super-Bond resin for luting metallic restorations and for restoring tooth defects. However, care is required in selecting appropriate clinical cases.     

Quantification of bone in dental implant sites after composite grafting of the mandible: report of a case

The amount of viable bone in a composite graft that consisted of autogenous iliac bone marrow, allogenic rib, and porous hydroxyapatite was quantified using standard histologic techniques and an optical insert disk prior to placement of endosteal implants in an augmented mandible. It is suggested that this technique could be used in such cases before deciding whether to proceed with implant insertion.     

Controlling contacts and contours using preformed ceramic inserts

Current adhesive techniques and materials that seal both enamel and dentin have revolutionized modern restorative dentistry. Unfortunately, the durability problems associated with direct polymeric materials of the past have not been adequately solved. Nevertheless, when cost and esthetics form part of the treatment decision process, patients presenting with Class 2 defects are most often provided with a direct restorative option. Direct composite resin restorations are fraught with problems largely related to the mechanical stresses that accompany polymerization shrinkage. A partial solution is to incorporate prefabricated ceramic inserts into the substance of the composite resin, thereby decreasing the volume of directly cured restorative material and effectively reducing the magnitude of the polymerization stresses. SONICSYS approx is a unique addition to the restorative continuum that takes the insert strategy one step further by using specifically shaped sonically driven diamond-coated preparation tips to adjust the cavity form to fit presized ceramic proximal inlays. The SONICSYS approx system represents a technique intermediate between a direct resin composite and a laboratory fabricated inlay. This article describes the background of this development, and the components and application of the system. In addition, within the presentation of a case study, operative innovations are introduced that improve interfacial integrity and allow for the conveyance of predictable contacts and proper physiological contour.     

Effect of novel filler particles on the mechanical and wear properties of dental composites.

OBJECTIVES: The purpose of this study was to investigate the method of producing pre-polymerized fused-fiber filler modified composite (PP-FFMC) particles and the effectiveness of incorporating these novel filler particles into dental composites. METHODS: Fused-fiber filler (FFF) blocks were impregnated with composite by two different methods. Three-point flexure tests were utilized to determine which was more effective. In order to assess the effect of the addition of PP-FFMC particles, two Bis-GMA/TEGDMA based conventional composite compositions were utilized as baselines, to which the novel particles were added. Mechanical and wear tests were performed to determine the fracture toughness, biaxial flexure strength, and in vitro wear of the materials. RESULTS: Mechanical testing showed that the addition of PP-FFMC particles decreased the strength and toughness of the conventional composites. Wear tests indicated that addition of the same particles improved the wear behavior of the conventional composites. SEM analysis of the fracture surfaces indicated that the PP-FFMC particles were incorporated without creating porosity, and that fracture was transgranular through the reinforcing particles. Microscopic flaws observed in the novel particles are the likely explanation for the observed strength and toughness values. SIGNIFICANCE:The results indicate that PP-FFMC particles have the potential to improve the wear properties of dental composites, however, they adversely affect the fracture behavior. Existing processing techniques for these particles, which introduce imperfections, limit their current usefulness.     

Microleakage of resin composite restorations with glass-ceramic inserts.

OBJECTIVE: The purpose of this study was to evaluate the effects of glass-ceramic inserts and different application techniques of resin composites on marginal leakage. METHOD AND MATERIALS: Three groups of 10 standardized, round, Class V cavities were prepared on the buccal surface of 30 extracted human molar teeth. Group 1 received resin composite restorations, placed in one increment (bulk). Group 2 received resin composite restorations that were placed in two increments, and group 3 received resin composite restorations with beta-quartz ceramic inserts. After the teeth were thermocycled and placed in 0.5% basic fuchsin for 24 hours, they were sectioned and examined for microleakage. RESULTS: On the occlusal margins, there was no statistically significant difference between the restorations placed with the incremental technique and the restorations with beta-quartz inserts. The restorations placed with the bulk technique had significantly more microleakage than did the others. On the gingival margins, the restorations with beta-quartz inserts exhibited significantly less microleakage than did the other groups. The restorations placed with the bulk technique showed significantly more dye penetration than did the others. CONCLUSION: The use of a glass-ceramic insert reduced the marginal leakage of Class V resin composite restorations.     

Ceramic inserts do not generally improve resin composite margins

summary Ceramic inserts are reported to possibly reduce polymerization shrinkage for posterior resin composite fillings. The aim of the present investigation was to evaluate the effect of different insert systems before and after thermomechanical loading. Sixty sound human third molars received occlusomesial Class II cavities, 40 with proximal margins 2 mm above and 20 with proximal margins 1 mm below the cementum-enamel junction. The specimens were randomly assigned to one of the six experimental groups (n = 10). The enamel-bordered cavities were restored with Syntac classic and Tetric Ceram (ST), Syntac classic, Tetric Ceram and beta-quartz inserts (TB), Syntac classic, Tetric Ceram and Cerana inserts (TC), Syntac classic, Tetric flow and SonicSys approx inserts (TS). The dentin-limited cavities were filled with Syntac classic and Tetic Ceram (DT), Syntac classic, Tetric flow and SonicSys approx inserts (DS). Before and after thermomechanical loading (100 000 x 50 N, 2500 x 5 degrees C/55 degrees C), replicas were made and both interfaces tooth/composite and insert/composite were examined under a scanning electron microscope at 200x. The Cerana and SonicSys insert groups showed significantly less gaps in enamel (P < 0.05). With beta-quartz inserts, no reduction of gaps was found (P > 0.05). Marginal integrity in dentine-bordered specimens could not be improved with SonicSys inserts (P > 0.05). The bonding performance insert/composite was promising for all IPS Empress inserts (Cerana, SonicSys enamel) but worse for beta-quartz inserts. Regarding gap formation between resin composite and tooth, Cerana and SonicSys inserts significantly reduced gaps. The use of SonicSys inserts in deep proximal cavities cannot be recommended.     

Evaluation of subsurface defects created during the finishing of composites.

The objective of this study was to test the hypothesis that a degraded subsurface layer containing microcracks is produced in dental composites as a result of finishing procedures. Various composites in the form of rectangular bars were finished with a 12-fluted carbide bur or a fine diamond within minutes of light-curing, and were subsequently stained with silver nitrate. Microscopic evaluation revealed that significant penetration of stain occurred in the unfinished as well as in the finished surfaces. The extent of dye penetration that could be directly attributed to a damaged layer produced by the finishing procedure was less than 10 microns, being greatest for a microfill (Silux Plus) and a hybrid (P-50) composite. There was no difference between the effects of the finishing instruments. SEM analysis of the subsurface showed an absence of any cracks for the composites. However, occasional disruption of the interface between the pre-polymerized resin fillers and the matrix was apparent for the microfill material. The results showed that only a very limited subsurface damage may be created in certain composites during the initial contouring of a restoration.     

Polymerization shrinkage and contraction stress of dental resin composites

OBJECTIVE: The aim of this study was to evaluate the shrinkage, contraction stress, tensile modulus, and the flow factor of 17 commercially available dental resin composites. METHOD: The volumetric shrinkage measurements were performed by mercury dilatometry, and the contraction stress and tensile modulus were determined by means of stress-strain analysis. The statistical analysis was conducted by ANOVA and Tukey's post hoc test, and linear regression. RESULTS: Strong linear correlation for most resin composites were found for (i) contraction stress and shrinkage (ii) contraction stress and tensile modulus, and (iii) shrinkage and tensile modules. For most of the materials the unpolymerized resin content determines the amount of shrinkage, contraction stress and tensile modules. The pre-polymerized clusters in Heliomolar results in improved shrinkage/contraction stress properties. The shrinkage/contraction stress for Filtek Z100, Aelite Flo, and Flow-it was too high for the amount of resin in the resin composite. This was rationalized by high polymerization rates, a flow factor, and the nature of the resin. SIGNIFICANCE: High shrinkage and/or high contraction stress may lead to failure of the bond between the resin composites and the tooth structure. This study shows that the unpolymerized resin content determines the amount of shrinkage, contraction stress and tensile modules. Therefore, using pre-polymerized clusters will improve shrinkage/contraction stress properties, as was shown in Heliomolar, while high polymerization rates, and low flow factors have a deteriorative effect on the shrinkage/contraction stress properties.     

An improved split-denture technique

A technique for the construction of split dentures with a cast framework to hold the denture segments together has been described. The advantages of this technique to the patient were noted. Patients are carefully instructed first on how to insert the sections and then on how to insert the casting after the individual segments of each arch are in place.     

Otic axis locator: closing the accuracy gap in cephalometrics and cast mounting.

An overview is presented of a new technique to improve the accuracy and reproducibility of earpost-dependent orientation in procedures such as cephalometric radiography and cast mounting, using a custom-molded ear canal insert to provide a stable fitted socket for more exact earpost fit. This is especially valuable in follow-up treatment and serial studies because the insert can be filed for future use on the same patient to provide identical positioning in successive registrations. Cephalometric radiography is further enhanced by the addition of a radiopaque x-ray marker deep in the canal, otherwise inaccessible, close to the bony ear canal (anatomical porion) and the mandibular condyle. This marker is also visible in all 3 cephalometric views-lateral, frontal (posteroanterior) and coronal (submental-vertex)-providing an exact common horizontal axis (Otic axis) for a three-dimensional Cartesian coordinate system of measurement.     

Eight year results with direct ceramic restorations (Cerana)

BACKGROUND: Single-visit system ceramic restorations are now in use to provide an alternative to resin-based materials. Inserts have been shown to improve characteristics of composite restorations. OBJECTIVE: To investigate the longevity of Cerana (Nordiska Dental, Sweden) in a prospective clinical trial. METHODS: Cerana restorations use matched drills with pre-etched and silanated leucite inserts cemented using a conventional restorative composite resin material. The results of 33 Cerana restorations up to eight years (25 Class I, eight class II) are presented. Restorations were reviewed and assessed by two examiners using modified USPHS criteria for anatomical form (AF) A-C, marginal adaptation (MA) A-D, surface roughness (SR) A-D, marginal discoloration (MD) A-C, colour match (CM) A-C and discomfort (DT) A-D as well as retention. RESULTS: The percentage of A scores for AF, MA, SR, MD, CM and DT at baseline (n = 33) were: 100, 100, 79, 100, 21, 100; after two years (n = 27) 100, 85, 33, 100, 19, 100 and after four years (n = 24) 96, 75, 17, 96, 25, 100. At six years (n = 20) 95, 70, 10, 95, 15, 100 and finally at the eight year recall (n = 18) 94, 61, 0, 94, 6, 100. AF was maintained in all except for one fractured marginal ridge. MA of the insert was good but composite was lost where exposed. SR increased to a B score for all inserts. MD at B grade was observed in 6% between composite and tooth but none between insert and composite. CM was stable in all cases. DT nil in all. There were no scores less than B. All reviewed restorations were retained, clinically acceptable and in function except for two lost for reasons not directly related to the Cerana insert. One class II restoration had a fractured marginal ridge but otherwise remains satisfactory. CONCLUSIONS: The results suggest that these restorations can be expected to perform well. Cerana is acceptable in terms of aesthetics, patient acceptance, occlusal wear and ease of use and is a good alternative for a single-visit, tooth coloured restoration in suitable cavity shapes.     

Bone and soft connective tissue response to porous acrylic implants. A histokinetic study

The ingrowth kinetics of soft and hard tissues near pre-polymerized and in-situ-polymerized large pore, in-situ-polymerized small pore and solid acrylic implants were investigated. Empty cavities served as controls. Aqueous sodium carboxymethyl cellulose (CMC) gel was dispersed in bone cement to create interconnected porosity. After periods of insertion from 2 days up to 26 weeks in frontal and parietal bones in pigs, tissue blocks containing implants were embedded in JB4 and studied by light microscopy. After the disappearance of the CMC-gel, at first only cells invaded the large pore implants but necrotized when at some distance from the implant surface. Later, when blood vessels grew into the pores, accompanying vital fibrous connective tissue was observed. Finally, all pores were filled with connective tissue. Surrounding bone was first resorbed, starting at day 7, creating a soft tissue interface. A zone of bone deposition, starting deep in the remaining bone at day 2, moved towards the implant, thereby bridging the soft tissue interface. At 6 weeks bone grew into the pores, thus anchoring the implant. Continuing deposition of bone around the implant provided a so-called lamina dura effect with all implants. Qualitatively similar tissue kinetics were observed around solid and pre-polymerized large pore implants, evidently in the case of solid implants without tissue ingrowth. Into the small pore implants only superficial soft or hard tissue ingrowth was seen because of the too small interconnections.     

A comparative study of the strength of aluminous porcelain jacket crowns constructed with the conventional and twin foil technique

The purpose of this study was to evaluate and compare the strength of aluminous porcelain jacket crowns made in the following manners: (1) the conventional technique, (2) the conventional technique with a pure alumina insert, (3) the twin foil technique, and (4) the twin foil technique with a pure alumina insert. The conclusions of this investigation can be summarized as follows: 1. Porosity was observed in all the restorations made by each of the techniques. 2. The porosity was greater at the porcelain-platinum foil interface than anywhere else throughout the restoration with both the conventional and twin foil techniques. 3. The porosity seemed to be evenly distributed along the interface, with no concentration in any area. 4. Regardless of the technique, crowns that were more porous fractured at lower values. 5. Crowns built by the twin foil technique were significantly more porous at the interface of the tin-plated platinum and the porcelain core than those built by the conventional technique. 6. Crowns constructed with the conventional technique were significantly stronger than those constructed with the twin foil technique. 7. There was no bond between the core porcelain and the platinum foil matrix in crowns constructed by the conventional technique. 8. There seemed to be a strong bond between the core porcelain and the tin-plated platinum matrix in crowns built by the twin foil technique. 9. The presence or absence of the alumina insert on crowns constructed with the conventional and twin foil technique did not affect the strength of the crowns when tested at the incisal edge.     

Fracture resistance of class II preformed ceramic insert and direct composite resin restorations

Objectives. This study aimed to compare the fracture resistance of two different posterior restorations in class II cavities.Methods. In this study 24 extracted intact human mandibular molars (for testing) and 24 extracted intact human teeth (for achieving contact) were used. The test teeth were divided into two groups and then mounted in normal anatomic relationship with intact human teeth on the same holder. Thus 12 pairs of teeth were constituted in each group. Class II MO cavities were prepared on testing teeth in each holder. The other tooth was used for achieving contact. The cavities in group 1 were restored with direct composite resin with the manufacturer's flowable composite. The cavities in group 2 were restored with SONICSYS inlays (preformed ceramic insert) according to the manufacturer's instructions. The marginal ridges of the restorations were loaded at an angle of 13.5 degrees to the long axis of the tooth in an Instron testing machine until failure occurred.Results. Analysis of mean failure loads indicated that class II SONICSYS inlay restorations (group 2) had a significantly greater fracture resistance than did class II direct composite resin restorations with flowable composite (P=0.000).Conclusions. The SONICSYS inlay system provided greater fracture resistance than direct composite resin with flowable composite.