Annual review of selected dental literature: report of the Committee on Scientific Investigation of the American Academy of Restorative Dentistry.
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Dental Caries↗
Biomedical subjects
John O Burgess
Publications and source records attributed to John O Burgess.
Shear bond strength with increasing light-guide distance from dentin.
BACKGROUND: In Class II composite restorations, the adhesive covering the gingival floor of the deep cavity preparation is 2 to 8 mm from the light guide and may not be adequately cured with a typical 10-second curing time. PURPOSE: The purpose of this study was to evaluate the dentin bond strengths of resin composite when the curing light guide (quartz-tungsten-halogen light) was placed at various distances and to investigate the relationships between radiant exposure, degree of conversion, and shear bond strength. MATERIALS AND METHODS: Single Bond (3M ESPE, St. Paul, MN, USA) was placed onto the dentin following the manufacturer's directions. Four groups of 10 teeth were cured for 20 seconds through a 0, 2.3, 4.6, or 6.9 mm spacer. Two other groups of 10 teeth were cured through a 4.6 mm spacer for 40 seconds and 60 seconds, respectively. Z100 resin composite (3M ESPE) was placed over the cured adhesive and polymerized at the same distance as the adhesive. After 24 hours of storage in water, the shear bond strengths were tested. The irradiance through each spacer was measured using a digital radiometer. The degree of conversion of the adhesive was determined by near infrared spectroscopy. The data were analyzed using analysis of variance and Tukey-B post hoc tests. RESULTS: Dentin shear bond strengths decreased significantly with increasing distance, but they increased significantly when the curing time increased from 20 to 40 or 60 seconds. There is a linear correlation between shear bond strength, degree of conversion, and logarithm (radiant exposure). CONCLUSION: Increasing curing time can compensate for the decreased bond strength owing to a decreased irradiance associated with increased curing distance. CLINICAL SIGNIFICANCE: Under the conditions of this study, when curing the adhesives in deep proximal boxes with a quartz-tungsten-halogen light, the curing time should be increased to 40 to 60 seconds to ensure optimal polymerization.
Analysis of Variance↗
Clinical evaluation of 2 flowable composites.
OBJECTIVE: This study evaluated the clinical efficacy of 2 flowable resin composites used to restore occlusal carious lesions. Tetric Flow (Vivadent) and Esthet-X Flow (Dentsply/Caulk) are resin composites with decreased filler loading and lower viscosity compared to conventional resin composites. METHOD AND MATERIALS: Sixty occlusal restorations (30 of each material) were placed. After tooth preparation and caries removal, each material was inserted with rubber dam isolation. Prime & Bond NT (Dentsply/Caulk) was used to bond both flowable composites, which were incrementally placed and light-cured for 20 seconds. Each restoration was evaluated at baseline (1 week after restoration placement), 3 months, 6 months, and 1 year for marginal discoloration, secondary caries, anatomic form, retention, polishability, marginal adaptation, and color match. Groups were compared at 1 year and the data analyzed statistically with a .05 level of significance. RESULTS: A marginally significant difference in color match was observed at 1 year (favoring Esthet-X Flow). No other differences were observed between materials. Marginal discoloration significantly worsened for all restorations at 6 months and 1 year, and marginal adaptation significantly worsened at 1 year for all restorations. A positive association between preparation size and sensitivity was detected at 3 months; no association was found at 6 months and 1 year. At 1 year, restoration size was positively associated with marginal adaptation. Despite some changes from baseline, all restorations were clinically acceptable at 1 year. CONCLUSION: Although flowable resin composites are advocated for occlusal restorations, it is recommended that they be limited to small and moderate-sized restorations.
Composite Resins↗
Formulation and characterization of a novel fluoride-releasing dental composite.
OBJECTIVES: The aims of this study were to formulate a novel fluoride-releasing dental composite and to evaluate its mechanical properties, fluoride release and recharge capabilities, water sorption and solubility. METHODS: A fluoride-releasing dimethacrylate monomer containing a ternary zirconium fluoride chelate was synthesized. Three experimental fluoride-releasing composites were fabricated with different monomer formulas (wt.%)-(1) Control A: 40 BisGMA/40 TEDMA/20 UEDMA; (2) EXPERIMENTAL: 20 F-releasing monomer/20 BisGMA/40 TEDMA/20 UEDMA; (3) Control B: the same formula as Control A except that it contained 10 wt.% (of total monomer) tetrabutylammonium fluoride (TBAF), which had a fluoride content equivalent to EXPERIMENTAL. All three materials had the same filler content: 55 wt.% silanized fluoroaluminosilicate particles (0.8 microm) and 10 wt.% silanized fumed silica (14 nm). All materials contained 0.17 wt.% camphorquinone (CQ) as a photoinitiator and 0.69 wt.% ethyl-4-dimethylaminobenzoate (4EDMAB) as an accelerator. The materials were tested for fluoride release (for 184 days), fluoride recharge, compressive and flexure strength, water sorption and solubility. The data were analyzed using ANOVA and Tukey-HSD tests, and Kruskal-Wallis test. RESULTS: The experimental composite had significantly higher fluoride release and fluoride recharge capabilities than both Control composites. It had significantly better physical and mechanical properties than Control B. SIGNIFICANCE: The combined use of the fluoride-releasing dimethacrylate monomer and fluoride-releasing filler can provide sustained high fluoride release and recharge as well as acceptable mechanical and physical properties. Simply adding organic fluoride salt in the monomer yields composites with poor mechanical and physical properties.
4-Aminobenzoic Acid↗
Selected characteristics of a new polyvinyl siloxane impression material--a randomized clinical trial.
OBJECTIVES: This study evaluated the ability of a new polyvinyl siloxane impression material (Affinis, Coltène/Whaledent, material A) to obtain final impressions free of bubbles and voids for indirect fixed cuspal-coverage restorations. The results were compared to a control polyvinyl siloxane impression material (material B). Both materials were handled by inexperienced clinicians (undergraduate dental students) in student clinics. METHOD AND MATERIALS: One-hundred and thirty patients who were treated in the Louisiana State University School of Dentistry Junior Student Clinic for indirect fixed cuspal-coverage restorations and who met the inclusion criteria were randomly assigned to either one of two treatment groups, group A (n = 65) or group B (n = 65). Two calibrated examiners evaluated the first impression of prepared posterior teeth at a magnification of 10x for acceptability (no voids or bubbles). Position of tooth, type of preparation, preparation finish line (Class I-V), and gingival bleeding scores were recorded. All statistical tests were performed with the level of significance set at .05. RESULTS: The Fisher-Freeman-Halton test did not reveal significant associations between material and gingival bleeding score (P = .492). Significant differences in the location of the preparation finish line between materials were observed (P = .0096); material A was more frequently used in cases where the preparation finish line was located at least 2 mm subgingivally. Logistic regression was used to assess the effect of the material on the success of the impression (acceptable/ unacceptable). Material was highly significant in the logistic model (P < .001) with an odds in favor of an acceptable impression being eight times higher with material A than with material B (odds ratio = 8.00; 95% confidence index for odds ratio: 2.832, 22.601). The 60/65 (92.3%) impressions made with material A and 39/65 (60%) impressions made with material B were rated "acceptable." CONCLUSION: The new polyvinyl siloxane impression material provided a significantly higher proportion of impressions free of bubbles and voids than the control polyvinyl siloxane material.
Chi-Square Distribution↗
Clinical evaluation of four Class 5 restorative materials: 3-year recall.
PURPOSE: To place four restorative materials, including two resin-based composites (Pertac III and Synergy), an improved resin-modified glass-ionomer (Fuji II LC Improved), and a compomer (Dyract AP), in Class 5 non-carious cervical lesions and to evaluate and compare those restorations for marginal discoloration, anatomic form, surface texture, secondary caries, retention, and marginal adaptation at baseline and annually for 3 years. METHODS: The tested materials were used to restore moderate-size Class 5 non-carious cervical lesions. All materials were used following the manufacturers' directions for etching, bonding, curing, and finishing. Thirty restorations of each material were placed. After rubber-dam isolation, a bevel was placed on the occlusal margin of all preparations except the Fuji II LC Improved, and all preparations were cleaned with pumice. Each restorative material was placed and cured in increments except Fuji II LC Improved. All restorations were evaluated at baseline, 6 months, 1, 2, and 3-year recalls using a modified USPHS scale. RESULTS: Analysis with Chi Square and Logit Analysis revealed that, at 3 years, Pertac III and Fuji II LC Improved were significantly rougher than all other materials. Pertac III had significantly poorer marginal adaptation than all other materials. All other comparisons were not significant. At 3-year recall, most restorations were satisfactory.
Acid Etching, Dental↗
In vitro durability of the resin bond to feldspathic ceramics.
PURPOSE: To measure and compare shear bond strength of three different resin-based composite cements (Panavia 21, Noribond DC, and Variolink II) to two feldspathic ceramic materials (Noritake EX-3 and Ceramco) after 3 days (at baseline) and after 180 days of water storage and repeated thermocycling. METHODS: Composite cylinders were bonded with Panavia 21, Noribond DC, and Variolink II to the hydrofluoric acid (HF)-etched surfaces of either Noritake Super Porcelain EX-3 (NEX) or Ceramco (CER) following the manufacturers' directions. Subgroups of 15 specimens were stored in distilled water for either 3 days without thermocycling or 180 days with 12,000 thermal cycles. Shear bond strength was measured and compared by loading each specimen in shear to failure in an Instron testing system. Data were analyzed with a three-factor ANOVA model. Post-hoc multiple comparisons of the individual main-effect levels were performed with Tukey's HSD multiple comparison procedure (alpha = 0.05). RESULTS: Mean bond strength did not differ for the two ceramic materials. Differences in mean bond strength were found among the bonding systems and between the early and late time points. Panavia exhibited significantly lower bond strength as compared to Noribond and Variolink II for both early and late time points, with a greater difference at 180 days. For all groups, failure modes were almost exclusively cohesive in the ceramic, which indicates sufficient resin-ceramic bonds with all tested materials.
Acid Etching, Dental↗
Comparing resin-based composites.
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Color↗
Shear bond strength of four core materials to dentin bonded with light-cured or dual-cured adhesive.
PURPOSE: To measure and compare the shear bond strength of four core materials to dentin bonded with one adhesive (Prime and Bond NT) that was either light-cured or dual-cured. METHODS: The dentin of 80 freshly extracted molars was exposed using a series of abrasive disks. The teeth were divided into eight equal groups, etched with phosphoric acid for 15 seconds and rinsed. Dentin was dried to a moist surface. On 40 teeth, Prime and Bond NT was applied and light-cured for 30 seconds. On 40 teeth, Prime and Bond NT was mixed with the self-cure additive, which was applied to the dentin, and light-cured for 20 seconds. The core materials were then placed following manufacturers' directions onto the cured adhesive. The core material was light-cured, when it was necessary, for 60 seconds and stored for 24 hours in water at room temperature. The specimens were loaded in shear in the Instron until failure at a 5 mm/minute crosshead speed. Data were compared using two factor ANOVA and Tukey's HSD test (P = .05). RESULTS: Both curing mode and core material showed a significant difference. A significant difference between mean shear bond strength for dual and light cured was observed only in CompCore (P = 0.0002). There was no statistical difference when Prime and Bond NT dual-cured was used with chemical- or dual-cured materials.
Acid Etching, Dental↗
Compressive strength, fluoride release and recharge of fluoride-releasing materials.
The compressive strength, fluoride releases and recharge profiles of 15 commercial fluoride-releasing restorative materials have been studied. The materials include glass ionomers (Fuji IX, Ketac Molar, Ketac Silver, and Miracle Mix), resin-modified glass ionomers (Fuji II LC Improved, Photac-Fil, and Vitremer), compomers (Compoglass, Dyract AP, F2000, and Hytac) and composite resins (Ariston pHc, Solitaire, Surefil and Tetric Ceram). A negative linear correlation was found between the compressive strength and fluoride release (r(2)=0.7741), i.e., restorative materials with high fluoride release have lower mechanical properties. The fluoride-releasing ability can be partially regenerated or recharged by using a topical fluoride agent. In general, materials with higher initial fluoride release have higher recharge capability (r(2)=0.7088). Five equations have been used in curve fitting to describe the cumulative fluoride release from different materials. The equation [F](c)=[F](I)(1-e(-bt))+betat best describes the cumulative fluoride release for most glass ionomers, resin-modified glass ionomers, and some high fluoride-releasing compomers and composites, whereas [F](c)=[F](I)/(t(1/2)+t)+alphat best describes the cumulative fluoride release for most compomers and composite resins. The clinic applications of different fluoride-releasing materials have also been discussed.
Cariostatic Agents↗
Three restorative materials and topical fluoride gel used in xerostomic patients: a clinical comparison.
BACKGROUND: The authors compare the incidence of recurrent caries around two glass ionomer restorative materials and one amalgam material. METHODS: The authors placed 111 restorations in nine xerostomic patients. Patients were given oral hygiene instructions and fluoride gel to use daily. The authors evaluated the restorations clinically and with photographs and impressions at six months, one year and two years according to criteria for marginal adaptation, anatomical form, caries in adjacent tooth structure and caries at the cavosurface margin. The authors divided patients into users and nonusers of fluoride. RESULTS: At the two-year recall appointments, the authors evaluated 95 (86 percent) of the 111 restorations. They analyzed two-year data using an analysis of variance for repeated measures and Fisher's post hoc test. The study results showed no significant differences among materials in regard to caries at the cavosurface margin among fluoride users. However, among fluoride nonusers, patients with amalgam restorations had a significantly higher incidence of caries at the cavosurface margins than did patients with either of the two glass ionomer restorations. The authors found no statistically significant difference between restorations with regard to marginal integrity or anatomical form. However, one patient exhibited failure of glass ionomer restorations owing to material loss. CONCLUSIONS: Less caries developed at the margins of glass ionomer restorations compared with amalgam restorations in xerostomic patients who did not routinely use a neutral topical sodium fluoride gel. CLINICAL IMPLICATIONS: Fluoride-releasing materials may reduce caries surrounding restorations in high-risk patients who do not routinely use topical fluoride. Patients who routinely used topical fluoride gel did not develop recurrent caries, and clinicians should encourage the use of fluoride gel on a daily basis.
Analysis of Variance↗
Three-dimensional analysis of dual-arch impression trays.
OBJECTIVE: The objective of this investigation was to measure and compare the dimensions of casts made using four types of impression trays and two impression materials to the dimensions of the original master model. This study differed from previous studies by using three-dimensional measurement. METHOD AND MATERIALS: Vinyl polysiloxane and polyether impressions were made of two crown preparations of ivorine teeth cemented into an acrylic master model. Two grooves were placed into each of the preparations. In addition, six points were placed on each occlusal surface and six were placed on each finish line. Impressions were poured with a Type IV dental stone at 48 hours. A three-dimensional measuring system was used to determine coordinates of 32 points on the master model and resulting casts. Inter- and intratooth dimensions were calculated from the measured coordinates. RESULTS: The accuracy and precision of the impression techniques were assessed using analysis of variance (ANOVA) and Dunnett's t test. The ANOVA and Dunnett's t test indicated that only the custom tray did not detect any inaccuracies and was as reproducible as the master model. CONCLUSION: This study suggests that the custom tray technique is most accurate, even though all other techniques evaluated apparently produce clinically acceptable results.
Analysis of Variance↗
Complex single-tooth restorations.
There are many options for restoring the decimated dentition. [43] Excellent results can be obtained with many of the materials currently available. The restorative option will depend on the size and location of the lesion, adequate isolation for adhesive restorations, caries rate, the patient's age, the aesthetic needs of the patient, occlusal habits, maintenance of maximum tooth structure, the skill of the dentist, and the longevity desired for the restoration. Amalgam is a cost-effective material, and when used properly, it can provide many years of service. Aesthetic demands, the desire to strengthen teeth, [44] and concern about the safety of mercury in amalgam have increased the use of direct composites, ceramic material, and indirect composites. The main drawback with these materials, however, is their increased technique sensitivity and concerns about their longevity. Gold continues to be a cost-effective and predictable material if placed properly. Full-coverage gold or porcelain fused to metal provides long-term predictability but is more destructive and not as aesthetically appealing. The wide varieties of materials available provide both a challenge and an opportunity to place the most effective material for a particular patient. A thorough understanding of the available materials and their appropriate use is needed to achieve a long-lasting restoration that serves the patient's needs.
Acid Etching, Dental↗
Treating root-surface caries.
This article summarizes the effectiveness of restorative materials used to restore root surfaces, the mechanisms by which these materials reduce caries, and placement techniques for restoring root-surface lesions. Patients may be classified into low, medium, and high caries risk groups for root caries, and specific dental restorative material recommendations are made for each category. Effective plaque control, xylitol-containing chewing gums, antimicrobial agents, fluoride-releasing restorative materials, topically applied fluoride, and fluoride-containing toothpastes provide maximum protection for the high caries risk patient.
Age Factors↗
In vitro evaluation of the retention of composite fiber and stainless steel posts.
PURPOSE: This study compared the tensile retentive strength of composite fiber-reinforced dowels luted with a resin cement to stainless steel dowels luted with zinc phosphate cement. MATERIALS AND METHODS: The crowns of 40 extracted human mandibular premolars were removed with a separating disc 1-mm coronal to the cementoenamel junction. The teeth were randomly divided into 4 groups (n = 10). A post space was prepared in each specimen to a depth of 9 mm, using the drill supplied by the respective manufacturer. For the stainless steel post group, 1.25-mm-diameter posts were cemented with zinc phosphate cement. For the composite fiber reinforced groups, posts with diameters of 1.00, 1.25, and 1.50 mm were luted with a Bisphenol A-Glycidyl Methacrylate (BIS-GMA) resin bonding system (Jeneric/Pentron, Wallingford, CT) according to manufacturer specifications. The specimens were stored in a sealed container with a moist environment for 24 hours, placed in a fixture in an 801 Materials Test Systems (MTS) machine (MTS Systems Corp, Minneapolis, MN), and loaded in tension at a rate of 5.0 mm/min until failure. Differences among the 4 groups were determined using a one-way analysis of variance and Tukey-B post-hoc tests (alpha = 0.05). RESULTS: The mean loads to failure ranged from 43.9 +/- 10.4 kg for the stainless steel dowel group to 19.9 +/- 5.7 kg for the composite fiber-reinforced 1.00-mm-diameter group. The stainless steel post luted with zinc phosphate cement provided significantly greater tensile resistance than all composite fiber dowel groups. The retention of the 1.00-mm composite fiber-reinforced post was significantly less than the remaining groups. CONCLUSIONS: Under the conditions of this study, the stainless steel dowel luted with zinc phosphate cement provided significantly greater retention.
Analysis of Variance↗
Light curing--an update.
Light-cured, resin-based composite is an integral part of esthetic and restorative dentistry. This article reviews the performance and limitations of 4 types of curing lights and predicts that curing lights of the future will use light-emitting diode (LED). Currently, LED curing lights are not as powerful as plasma arc curing (PAC) or quartz tungsten halogen (QTH) lights. For the present, QTH curing lights dominate, but PAC lights cure increments of composite resin more efficiently. This article discusses different curing lights: QTH lights, PAC lights, laser curing units, and LED curing lights. The support for different curing modes (soft, exponential, and pulse delay) to improve marginal integrity and reduce marginal leakage is examined.
Composite Resins↗
Effect of placement agitation and placement time on the shear bond strength of 3 self-etching adhesives.
This study measured the shear bond strength (SBS) of 3 self-etching bonding agents to enamel and dentin with and without agitation at 3 different application times. The null hypotheses tested were that agitation and application time have no effect on bond strength. Occlusal surfaces of 180 recently extracted caries-free human molars were wet ground with 600 grit wet-dry silica carbide abrasive paper to obtain a flat enamel surface. The teeth were divided into 18 groups of 10 teeth. Three self-etching bonding agents, Clearfil SE BOND (Kuraray America), Xeno III (Dentsply) and AdheSE (Ivoclar-Vivadent) were applied using application times of 10, 20 or 30 seconds with or without agitation, thinned with a gentle stream of air and cured for 10 seconds, according to manufacturers' directions. Z100 (3M ESPE) composite, A2 shade, was placed over the cured adhesive and cured for 40 seconds. The samples were stored in distilled water at room temperature until testing. The samples were tested in shear to failure with a 1-mm/minute crosshead speed. After enamel shear bond strength testing, the teeth were again ground with 400 and 600-grit wet-dry SiC paper to obtain a flat dentin surface. The protocol used for preparing the enamel bond test samples was repeated, and the teeth were stored until testing in distilled water at room temperature. The samples were again tested in shear at a 1-mm/minute crosshead speed. Values were converted to MPa and data analyzed for intergroup differences using ANOVA and Tukey post-hoc tests. Agitation did not improve enamel SBS for any of the materials tested, but there was a significant difference in enamel SBS among materials: Clearfil SE Bond shear bond strength was greater than Xeno III, which was greater than AdheSE. At 10 seconds application time on dentin, agitation improved the Clearfil SE Bond SBS and, at 20 seconds application time on dentin, agitation significantly improved SBS to dentin for all systems tested. Agitation had no affect when the adhesive was applied to dentin for 30 seconds. Clearfil SE Bond SBS to dentin was significantly higher than the other self-etching adhesives tested except at 10 seconds without agitation.
Acrylic Resins↗
Six-year clinical evaluation of bonded and pin-retained complex amalgam restorations.
This clinical study compared the performance of complex amalgam restorations retained with self-threading pins or bonded with a filled, 4-META-based resin. Sixty amalgam restorations (28 pin-retained and 32 bonded), each replacing at least one cusp, were placed. Self-threading stainless steel pins (Coltene-Whaledent) were used in the pin-retained group. A filled, 4-META-based bonding resin (Amalgambond Plus with HPA powder) was used in the bonded group. For both groups, any retention form remaining after removal of an old restoration was left in place but not enhanced. At six years, 11 restorations had failed; eight of which were pin-retained and three bonded. Using Fisher's exact test to compare the groups at six years, there was no significant difference in failure rate, marginal adaptation, marginal discoloration, secondary caries, tooth sensitivity or tooth vitality. At six years, there was no difference in the performance of pin-retained amalgam restorations and bonded amalgam restorations.
Acrylic Resins↗