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Two groups of schoolchildren between seven and 12 years old residing in the vicinity of a non-ferrous industrial plant and exposed to lead (Pb) at a concentration that could cause health problems, were monitored. Concentrations of Pb in blood (blood-Pb), which were determined at regular six monthly intervals, were related to the Pb concentrations in surface tooth enamel (enamel-Pb). Acid etch biopsy samples of surface enamel were taken at the end of the five year study period in the first group (A) and after two years in the second group (B). Salivary Pb (saliva-Pb) concentrations were determined for the first study group on the same day that the enamel biopsies were performed. Calibration of the data was necessary--that is, blood-Pb concentration with respect to age and sex and enamel-Pb concentration with respect to etch depth and age. The blood-Pb concentrations declined with time. Surface enamel Pb concentrations correlated with blood-Pb concentration for the period starting with the pre-eruptive development of the incisors, related to blood-Pb concentration for a long time, and corresponded partly to the exposure at the time of pre-eruptive development and/or eruption. Through the correlation with enamel-Pb concentration, the seasonal behaviour of blood-Pb concentration became apparent. Saliva-Pb concentrations related to blood-Pb concentrations only in the short term.

Seventy-six extracted human permanent canines and premolars with single canals were used in this study. The crowns were removed, the canals were instrumented, and the roots were randomly divided into four groups of 18 each. Three groups were medicated with Ca(OH)2 USP, Calasept, and Vitapex, respectively, while the control group was not medicated. The roots were incubated in 100% relative humidity at 37 degrees C for 1 wk, after which the medicaments were removed and the canals were enlarged to the next file size. One tooth in each group was examined in the scanning electron microscope while the remaining roots were filled with gutta-percha using a lateral condensation technique. The roots were placed in 2% methylene blue solution for 2 wk and both linear and volumetric dye penetration evaluated. A highly significant correlation between linear and volumetric leakage was observed. The leakage among the experimental groups was not significantly different, but was significantly less than in the control group.

To determine in vitro (1) the shear bond strengths (SBS) of the modified Gluma system to enamel and dentin; (2) the qualitative and the quantitative microleakage (ML) of Class V preparations on the cemento-enamel junction (CEJ) and in dentin, respectively, restored with the Gluma system; and (3) the effect of the system's components on enamel and dentin by scanning electron microscopy.Seventy-five extracted human maxillary permanent central incisors and 75 permanent first and second molars were embedded in brass tooth cups with cold-cure acrylic resin. The facial surfaces of the anterior and the occlusal surfaces of the molar teeth were ground wet on 180- followed by 600-grit silicon carbide paper. Demarcated sites on the surfaces were treated according to the manufacturer's instructions and Pekafill composite was bonded to the treated surfaces. Fifteen specimens prepared on enamel were removed 1 minute after cure (A) and the SBS determined. The remaining specimens were removed 15 minutes after final cure, stored in saline at 37 degrees C for 24 hours (B), for 1 week without (C) and with temperature cycling (D), and for 4 weeks (E). Similar regimens were used for dentin, groups F, G, H, I and J. The SBS were determined and expressed in MPa. The data were analyzed by ANOVA, Student-Newman-Keuls and t-tests. For the qualitative ML evaluation, Class V cavities were prepared on the CEJ of 30 human premolars and restored with Gluma/Pekafill. After thermocycling in 0.5% basic fuchsin, the teeth were sectioned and ranked according to the degree of microleakage. Class V cavities were prepared on the facial root surfaces of 15 human premolars and restored. The ML was determined quantitatively by a spectrophotometric dye-recovery method and expressed as microgram dye/restoration.The mean +/- SD of the SBS in MPa were: A: 14.6 +/- 2.2; B: 21.2 +/- 1.6; C: 20.5 +/- 1.4; D: 24.2 +/- 2.0; E: 22.8 +/- 3.7; F: 7.0 +/- 2.0; G: 16.1 +/- 4.0; H: 15.6 +/- 3.7; I: 10.9 +/- 3.3; J: 14.4 +/- 3.3. The quantitative ML was 1.00 +/- 0.39 microgram dye/restoration. The lowest SBS were obtained on specimens tested after 1 minute. Temperature cycling had a significantly adverse effect on the SBS to dentin (P = 0.0003). Etch patterns conducive to bonding were produced on the enamel. The resin system penetrated into the dentin tubules.

To evaluate the effectiveness of various surface treatments for glass ionomer cement (GIC) by determining quantity of dye uptake spectrophotometrically.Sixty specimens, 4.5 mm diameter and 2 mm thick, were made from Shofu GIC and divided into 10 groups. Positive control (A) and negative control (B) specimens were not protected while experimental specimens were protected with ARM chemically-cured bonding resin (C), Durafill Bond light-cured bonding resin (D), Bondlite light-cured bonding resin (E), Colorama nail varnish (F), Shofu varnish (G), Copalite varnish (H), Vaseline (I) or Vaseline followed by Copalite (J). The discs were immersed in 0.05% methylene blue solution 10 minutes after mixing except group B specimens which were immersed in deionized water. After 24 hours the discs were removed, washed, and individually placed in 1 ml 65% nitric acid for 36 hours. The solutions were filtered, centrifuged and the absorbance determined spectrophotometrically at 590 nm. Dye uptake was expressed in microgram dye/restoration and the data analyzed by ANOVA and Tukey Kramer test.The mean (SD) of dye uptake were: A:95.12 (11.28); B:0 (0); C:40.90 (5.06); D:33.89 (3.63); E:35.73 (3.36); F:3.29 (0.79); G:14.87 (2.86); H:21.99 (3.25); I:47.21 (7.06); J:29.74 (3.49). All the surface agents were effective in protecting setting restorative glass ionomer cement, but nail varnish provided the best results.

To determine the in vitro shear bond strengths and quantitative microleakage of four experimental bonding restorative systems used in conjunction with Metafil-A, an experimental composite that does not contain 4-META, and Metafil-Ex, a 4-META containing experimental composite.120 test specimens were prepared on dentin treated with Amalgambond Activator followed by the application of an experimental primer consisting of 35% glyceryl methacrylate. In 60 teeth the mixed Amalgambond Base and Catalyst was then applied while in the remaining 60 teeth this step was omitted. Cylinders of either Metafil-A or Metafil-Ex were bonded to the dentin surfaces and the test specimens removed from the assembly apparatus after 1 minute or after 15 minutes and the latter specimens were stored in saline at 37 degrees C for 24 hours prior to determining the shear bond strength in an Instron machine at a crosshead speed of 0.5 mm/minute. Sixty Class V preparations were made on the facial surfaces of the roots of extracted human premolars and the preparations restored with the four restorative systems. The quantitative microleakage was determined by a spectrophotometric dye-recovery method.The shear bond strengths were significantly lower when the 4-META-containing Amalgambond Base and Catalyst were not applied and were unmeasurable when Metafil-A was used as the composite. The quantitative microleakage of the latter system was significantly greater than when the other restorative systems were used.

To determine (1) the in vitro shear bond strengths of the A.R.T. Bond System to dentin at different time intervals, (2) the quantitative microleakage of Class V preparations in dentin restored with the A.R.T. Bond System, and (3) the resin penetration into the dentin tubules by scanning electron microscopy.The occlusal surfaces of 75 extracted human mandibular and maxillary permanent first and second molars were ground wet on 600-grit SiC to expose the superficial dentin. The A.R.T. Primer and the A.R.T. Adhesive were applied to demarcated bonding sites as recommended by the manufacturer. Brilliant Dentin resin composite was transferred to the opening in a split Teflon mold in the assembly apparatus in three increments, each compressed firmly and cured for 40 seconds. Fifteen specimens were disassembled 60 seconds after final cure and then tested. The remaining 60 teeth were disassembled 15 seconds after cure; one group was tested at this time and the others immersed in saline at 37 degrees C for 24 hours, 1 week and 4 weeks before being tested. A shear load was applied at a crosshead speed of 0.5 mm/minute, the shear bond strengths calculated and expressed in MPa. Data were analyzed by ANOVA and Student Newman-Keuls test. Class V cavities were prepared at the facial surfaces of 18 extracted human permanent premolars and restored. Microleakage was determined quantitatively by a spectrophotometric dye-recovery method and expressed as mg dye/restoration.Mean +/- SD of the shear bond strength in MPa were 13.07 +/- 3.59 (1 minute), 16.08 +/- 3.12 (15 minutes), 18.17 +/- 3.44 (24 hours), 17.54 +/- 5.35 (1 week), 17.90 +/- 2.61 (4 weeks). The mean +/- SD microleakage was 0.008 +/- 0.04 mg dye/restoration.

Two dentin bonding agents that contain phosphorus esters, (Clearfil Photo Bond and Panavia), and a bonding agent for porcelain, (Clearfil Porcelain Bond), have been introduced for bonding to enamel, dentin, amalgam, cast metal alloys and porcelain. The shear bond strengths were determined to enamel (Procedure A), to dentin (Procedure B), to amalgam (Procedure C), of amalgam to dentin (Procedure D), to cast metal alloy (Procedure E) and to porcelain (Procedure F). Also the quantitative microleakage of Class V restorations in cementum (dentin) was evaluated (Procedure G). The components were applied as directed by the manufacturer and a light-cured resin composite for posterior teeth, (Clearfil Photo Posterior) used. The mean +/- SD of the shear bond strengths recorded in MPa were: A = 24.15 +/- 3.65; B = 11.30 +/- 3.12; C = 13.77 +/- 3.42; D = 4.26 +/- 0.92; E = 17.84 +/- 3.19; F = 13.45 +/- 4.12. The quantitative microleakage (G) was 0.55 +/- 0.34 mg dye/restoration.

This study determined the shear bond strength (SBS) of composite bonded to chlorhexidine-treated enamel and untreated enamel. Fifty human molars were mounted in cold- cure acrylic and the superficial enamel of the buccal or lingual surface was exposed using 600-grit silicon carbide paper. During the experimental protocol, the control group (n = 25) and the experimental group (n = 25) were stored in distilled water at 37 degrees C. The experimental group was immersed in 0.12% chlorhexidine gluconate for 1 minute, 4 times daily, for 7 days. Prisma APH composite was then bonded to all samples following acid etching for 30 seconds, and the SBS was determined. Shear bond strengths for the control (13.23 +/- 3.22 MPa) and the experimental (13.67 +/- 4.59 MPa) groups were not significantly different using a t-test. The result may be attributed to either a lack of effect of chlorhexidine or to the acid etch which dissolves the affected superficial enamel leaving an unaffected substrate for bonding.

The purpose of this in vitro study was to determine the relationship between the shear bond strength [SBS] of seven dentin bonding systems to dentin and the quantitative microleakage [ML] of Class V preparations in dentin restored with these systems. The systems evaluated were All-Bond/Bisfil-P [A]; Syntac/Heliomolar [B]; XR-Bond/Herculite [C]; Scotchbond 2/Silux [D]; Denthesive/Charisma [E]; Prisma Universal Bond 2/Prisma AP.H [F]; and Tenure/Perfection [G]. The 115 specimens were removed from the assembly apparatus and stored in saline at 37 degrees C for 24 hours, the SBS determined and expressed in MPa. Fifteen Class V preparations in dentin were restored with each of the bonding systems, thermocycled 500x in 2% methylene blue solution between 50 degrees C and 8 degrees C, and the ML determined by means of a spectrophotometric dye-recovery method. The ML was expressed in microgram dye/restoration. The data were analyzed by ANOVA, Student-Newman-Keuls test, and linear regression analysis. The SBS in MPa were: A:17.2 +/- 3.6; B:15.9 +/- 2.1; C:15.4 +/- 3.7; D:11.6 +/- 2.2; E:10.7 +/- 3.7; F:10.4 +/- 2.5; G:8.2 +/- 3.9. The ML in microgram dye/restoration were: A:2.6 +/- 1.2; B:2.6 +/- 1.0; C:2.2 +/- 1.9; D:3.1 +/- 2.9; E:4.6 +/- 4.2; F:2.6 +/- 2.5; G:4.4 +/- 4.1. SBS = 20.91-2.60 [microgram dye]. The results suggest that a SBS of +/- 21 MPa may reduce ML to near zero.

Radiation caries is a well-known indirect side effect of head and neck radiotherapy. The initiation and progression of radiation caries were studied using an in situ model. The morphology of induced carious lesions was compared with that of natural radiation caries. Both natural and induced radiation caries showed the same patterns of decay; widespread areas with porosity of enamel, crater formation with exposure of subsurface enamel, preferential dissolution of prisms with hollowing out of prism cores, loss of large parts of surface enamel and loss of full enamel coverage exposing the underlying dentin. In irradiated patients most enamel slabs were severely demineralized within 6 weeks whereas in control subject the slabs showed no significant demineralization after 12 weeks. The model may offer an excellent opportunity to study preventive fluoride regimens because of the rapid induction of radiation caries and its similarity with natural lesions.

This in vitro study evaluated the quantitative microleakage (ML) of (A) Gluma/Pekafill, (B) Tripton/Opalux, (C) Syntac/Heliomolar, (D) Prisma Universal Bond 2/Prisma AP.H., (E) Prisma Universal Bond 3/Prisma AP.H., and (F) Clearfil PhotoBond/Photo Clearfil Bright to cementum (dentin) by means of a dye-recovery spectrophotometric technique. Standardized cylindrical Class V preparations, 3 mm in diameter and 1.5 mm deep, were made on the facial surfaces of the roots of ninety extracted human maxillary and mandibular permanent canines and the teeth were restored with the recommended resin composite. The root apices were removed, Class V preparations made at the cut apices and restored with two coats of Copalite varnish and amalgam. The teeth were painted with two coats of nail varnish except for 1 mm surrounding the restorations prior to thermocycling x500 in 2% methylene blue solution. Root sections including the restorations were placed in 50% HNO3, the dye extracted and the dye concentrations determined spectrophotometrically. Standard solutions with known amounts of dye were prepared in 50% HNO3 and unrestored root sections placed in these. ML was expressed as micrograms dye/restoration and data analyzed by ANOVA and Duncan's test. The following results were obtained: (A) 3.67 +/- 2.18; (B) 2.76 +/- 1.71; (C) 2.57 +/- 0.97; (D) 2.56 +/- 2.51; (E) 1.21 +/- 0.24; (F) 0.49 +/- 0.20. Clearfil PhotoBond and Prisma Universal Bond 3 showed significantly less microleakage than other systems evaluated.

The shear bond strengths (SBS) were determined to enamel etched with Uni-Etch (Procedure A) or treated with the mixed Primer A and B (Procedure B), to dentin treated with the Dentin Conditioner (Procedure C) or etched with All-Etch (Procedure D), to amalgam treated with the mixed Dual Opaquer Base and Catalyst which was allowed to self cure (Procedure E) or light cured (Procedure F), of amalgam to dentin (Procedure G), to cast metal alloy (Procedure H), and to porcelain (Procedure I). The test specimens were stored in physiological saline at 37 degrees C for 24 hours, and the SBS determined by the application of a shear load directed at the base of the bonded composite cylinders at a crosshead speed of 0.5 mm/minute. The SBS were calculated and expressed in MPa. Standardized Class V preparations were made at the facial aspects of the roots of the teeth, treated with the Dentin Conditioner (Procedure J) or etched with All-Etch (Procedure K). Quantitative microleakage (QM) was determined by means of a spectrophotometric dye-recovery method and expressed in microgram dye/restoration. The mean +/- SD of the SBS in MPa were: A: 18.3 +/- 2.1; B: 22.0 +/- 2.9; C: 17.2 +/- 3.6; D: 15.6 +/- 3.7; E: 12.9 +/- 1.9; F: 13.6 +/- 2.0; G: 13.0 +/- 3.5; H: 21.8 +/- 2.6; I: 8.2 +/- 2.8. The mean +/- SD of the QM in microgram dye/restoration were: J: 2.61 +/- 1.22 and K: 1.95 +/- 0.59. The analysis of the SBS data showed that the application of the Primer to enamel resulted in a significant increase in SBS.(ABSTRACT TRUNCATED AT 250 WORDS)

The purpose of this in vitro study was to determine the shear bond strength [SBS] of Syntac to dentin; to determine the quantitative microleakage (ML) of Class V preparations in dentin restored with the Syntac system; and to study resin penetration into the dentin tubules by SEM. The occlusal surfaces of 30 extracted human mandibular permanent first and second molars were ground wet on 600-grit SiC to expose the superficial dentin. The teeth were embedded in brass tooth cups with cold cure acrylic resin. The Syntac Primer and the Syntac Adhesive were applied to the demarcated bonding sites as recommended by the manufacturer. Radiopaque Heliomolar was transferred to the opening in a split teflon mold in three increments, each compressed firmly and cured for 40 seconds. Fifteen of the test specimens were disassembled 60 seconds after cure [A], and the remainder 15 min after cure and the latter specimens stored in saline at 37 degrees C for 24 hours [B]. A shear load was applied at a crosshead speed of 0.5 mm/min, the SBS calculated and expressed in MPa. The data were analyzed by a two-sample t-test. Class V cavities were prepared on the facial surfaces of 15 human premolars and restored. The ML was determined quantitatively by a spectrophotometric dye recovery method and expressed as microgram dye/restoration. The mean +/- SD of the SBS in MPa were: A: 10.14 +/- 2.80; B: 15.90 +/- 2.13 and the ML 2.57 +/- 0.97 microgram dye/restoration. The SBS recorded after 24 hours storage was significantly greater than after 1 minute (P0.0001). The bonding resin penetrated deeply into the dentin tubules.

The shear bond strengths (SBS) of the Amalgambond Adhesive System to several substrates were determined in vitro. Ninety extracted human permanent first and second molars were used. In 30 teeth, the occlusal surfaces were ground wet on 600-grit SiC to expose the enamel and in 60 to expose the superficial dentin. Amalgam (Tytin) restorations were placed on 15 exposed dentin surfaces and sandblasted. The Metafil-A composite was transferred in three increments and each cured for 30 seconds. The SBS of the composite to enamel were determined 1 minute (A) and 24 hours after final cure (B); to dentin 1 minute (C) and 24 hours after final cure (D); of freshly mixed amalgam to dentin (E) and to previously placed amalgam (F) after 24 hours. All of the 24 hours specimens were stored in saline at 37 degrees C or 24 hours. A shear load was applied to the base of the bonded cylinders with a knife-edged rod in an Instron machine at a crosshead speed of 0.5 mm/min. The SBS were expressed in MPa and the data analyzed by Student t-test, ANOVA and Student-Newman-Keuls test. The mean +/- SD of SBS were: A: 8.15 +/- 1.74; B: 15.69 +/- 4.50; C: 6.64 +/- 1.72; D: 17.09 +/- 4.61; E: 5.10 +/- 1.73; F: 6.54 +/- 3.78. The SBS to enamel and to dentin, respectively, after 24 hours were significantly greater than after 1 minute (P = 0.0001), the SBS of A vs C (P = 0.1783), B vs D (P = 0.2180) and E vs F (P = 0.7149) were not significantly different.

The purpose of this study was to determine the fluoride release by and the enamel, cementum and dentin fluoride uptake from a visible light-cured fluoride-containing resin composite. Seven circular discs of the composite were prepared and the fluoride release in distilled water determined at daily intervals for 14 days, and then after 30, 90, 180, 365 and 550 days. The baseline fluoride concentrations in enamel and cementum were determined in three successive depths by an acid etch biopsy procedure and in dentin by an abrasion biopsy procedure. Composite slabs were prepared and ligated to the enamel, cementum and dentin surfaces and the teeth were suspended in synthetic saliva for 7 or 30 days. After removal of the composite, similar biopsy procedures were performed. The teeth were then immersed in 1 M KOH for 24 hours and similar biopsies done. The fluoride concentrations were adjusted to standardized depths of 2.0 microns for enamel, 4.0 microns for cementum and 10.0 microns for dentin, and the total and bound fluoride uptake calculated. The fluoride release from the composite dropped sharply after 1 day and after 180 days reached a plateau which remained relatively constant up to 550 days. The results of this in vitro study indicated that the mineralized dental tissues acquired fluoride at various depths.

This study evaluated the microleakage of Class V resin restorations subjected to temperature and axial load cyclings. The preparations were made at the mesial and distal aspects of 29 mandibular first and second molars. The enamel margins were beveled, acid etched, washed and dried. Kerr XR Bonding System was applied to the dentin and etched enamel and Herculite composite cured in two increments. The teeth were stored in saline for 7 days, thermocycled x500 in 0.5% basic fuchsin between 8 degrees C and 50 degrees C (A); subjected to an occlusal load of 34 MPa in the dye without thermocycling (B); or followed by thermocycling (C). The leakage was scored from 0 to 4 at both the enamel and cementum aspects of the restorations. The data were analyzed by the Kruskal-Wallis test. The microstrain of five restored teeth subjected to an occlusal load of 34 MPa was measured. Microleakage of the mesial restorations was significantly greater at the cementum aspects of the restorations subjected to both temperature and occlusal loading when compared to the restorations subjected to temperature cycling or load cycling only. The microstrain in eight of the 10 restorations was significantly greater at the cementum aspects of the restorations than at the enamel aspects.

Thirty extracted human mandibular permanent first and second molars were used in this study. Class II preparations were made extending 1 mm below the CEJ at the mesial and 1 mm above the CEJ at the distal aspects. In 15 of the teeth Vitrebond was applied to all exposed dentin (A) while in 15 teeth the gingival floor was left exposed (B). After cure, the enamel margins were etched with H3PO4 gel and the Vitrebond surfaces were treated with Scotchbond 2. The P-50 was transferred to the approximal boxes and occlusal aspects in three increments, each compressed firmly and cured for 60 seconds. The restored teeth were stored in saline at 37 degrees C for 1 week. The teeth were thermocycled x250 in 0.5% basic fuchsin between 8 degrees C and 50 degrees C with a dwell time of 15 seconds. The teeth were embedded in epoxy resin and five mesiodistal sections cut. Microleakage at the mesial and distal aspects were scored from 0 to 3 depending on the extent of the microleakage. The data were analyzed by the Wilcoxon 2-sample and the matched pair signed rank tests. Leakage above the CEJ was significantly less than below the CEJ and significantly reduced when Vitrebond was extended to the cavosurface margins.

The purpose of this study was to determine the effect of pyruvic acid and glycine on the shear bond strength (SBS) of the Gluma Bonding System to dentin and enamel. Forty-five mandibular and maxillary permanent first and second molars and 45 maxillary permanent central incisors were used in the study. Fifteen test specimens were prepared with each of the following procedures. Dentin: using the conventional Gluma Bonding System (A); the Gluma 2 Cleanser was replaced with 10% pyruvic acid containing 10% glycine with pH 2.8 (B); or the dentin was etched with 10% pyruvic acid (pH 1.5) followed by the application of 10% glycine with pH adjusted to 9.0 (C). Enamel: etched with Gluma 1 Etchant (D); etched with 10% pyruvic acid containing 10% glycine (E); or etched with 10% pyruvic acid followed by the application of 10% glycine (F). The test specimens were disassembled 15 minutes after cure, stored in physiological saline at 37 degrees C for 24 hours, and the SBS determined in an Instron machine at a crosshead speed of 0.5 mm.min.-1 The SBS was expressed in MPa. The data were analyzed by ANOVA and the Student-Newman-Keuls test. The mean +/- SD of the SBS in MPa were: A: 8.7 +/- 5.2; B: 14.7 +/- 4.6; C: 12.8 +/- 4.8; D: 19.8 +/- 3.8; E: 18.0 +/- 3.1; F: 17.6 +/- 3.5. The application of 10% pyruvic acid containing 10% glycine, and 10% pyruvic acid followed by 10% glycine, resulted in a significant increase in SBS to dentin. The SBS to enamel treated with the three procedures were not significantly different.

This study determined the effect of phosphoric acid (H3PO4) application to dentin on the shear bond strength (SBS) and microleakage of an experimental bonding system. Thirty human maxillary permanent first and second molars were used for the SBS evaluation. In 15 of the teeth the Dentin Conditioner was applied to dentin for 30 seconds (A), while in the remaining 15 teeth the smear layer was removed by the application of a 37% H3PO4 gel for 20 seconds (B). The Primers 1 and 2 were mixed and applied to the conditioned dentin followed by the application of the Dentin Bonding Resin prior to the placement in three increments of the Bisfil-M composite. The specimens were stored in physiological saline at 37 degrees C for 24 hours prior to applying a shear load at a crosshead speed of 0.5 mm. inch-1 in an Instron machine. Shear bond strengths were expressed in MPa. Circular Class V preparations were made on the roots of 30 maxillary permanent canines, 15 restored using the Dentin Conditioner (C) and 15 by removing the smear layer with the H3PO4 gel (D). Microleakage of the restorations was determined quantitatively by means of a spectrophotometric method. The quantitative microleakage was expressed as microgram dye/restoration. The data were analyzed by the Student t-test. The following results were obtained: A: 14.2 +/- 2.2 MPa; B: 7.2 +/- 4.2 MPa; C: 30.0 +/- 28.6 micrograms dye/restoration; (D) 10.3 +/- 8.2 micrograms dye/restoration. Removing the smear layer with H3PO4 reduced the SBS to dentin but decreased the quantitative microleakage significantly.

Laboratory adhesion tests are performed as screening tests prior to the clinical evaluation of dentin bonding restorative systems. These tests include the determination of the bond strength to dentin and the evaluation of microleakage and marginal gap dimensions at the tooth-restoration interface. No standardized adhesion tests are available as the methodologies vary tremendously from one laboratory to another. The variable factors are reviewed in this manuscript and laboratory studies to standardize these procedures are proposed.

The purpose of this study was to determine the shear bond strengths of five commercially available fluoride-containing restorative systems to dentin and to evaluate the fluoride release from them. The five systems evaluated were: (A) Vitrabond/Silux; (B) Zionomer Powder Liquid/Perfection; (C) Zionomer Paste Paste/Perfection; (D) TimeLine/Prisma-Fil; and (E) GC Dental Cement/Fuji II. Eighteen test specimens were prepared on the dentin surfaces of extracted human permanent first and second molars ground on 600 grit SiC paper with each system. The bonded cylinders were removed from the assembly apparatus 15 minutes after cure, stored in physiological saline at 37 degrees C for 24 hours and subjected to a shear load at 0.5 mm/min. Five cylindrical specimens were prepared for each system, the discs were suspended in 25 microL glass distilled water and the fluoride release (microgram F/mm2) determined at daily intervals for 15 days and then after 30 and 90 days. The data were analyzed by a one-way analysis of variance and Duncan's multiple range test. The following shear bond strengths (Mean +/- SD) were recorded (MPa): A: 8.86 +/- 1.49; B: 4.24 +/- 1.23; C: 4.41 +/- 1.39; D: 3.85 +/- 1.60; E: 4.81 +/- 1.21. With all the systems, the fluoride release dropped sharply during the first 7 days and then remained constant. The shear bond strength and the fluoride release from Vitrabond/Silux were significantly greater than that of the other systems.

The purpose of this study was to determine the shear bond strengths and microleakage of Scotchbond 2/Silux to dentin and to evaluate resin penetration into the dentinal tubules of human and bovine teeth. The shear bond strengths (SBS) were determined on occlusal dentin of 25 human permanent molars (H) and on facial dentin of 25 bovine permanent mandibular incisors (B). The test specimens were stored in physiological saline at 37 degrees C for 24 hours prior to the application of a shear load in an Instron machine at a speed of 0.5 mm/min. Microleakage (ML) of Class V restorations placed on the facial surfaces of the roots of 15 human canines (H) and 15 bovine incisors (B) was determined quantitatively. The restored teeth were thermocycled x500 in 2% methylene blue solution, the dye extracted in 50% HNO3 and the dye concentrations determined spectrophotometrically. The resin penetration into the dentinal tubules was evaluated in the SEM. The following results were obtained: SBS (MPa): H, 6.2 +/- 2.9; B, 4.4 +/- 1.2; ML (microgram dye): H, 4.7 +/- 3.2; B, 15.9 +/- 10.5. The data were analyzed by t-test. The shear bond strength of Scotchbond 2/Silux to human dentin was significantly greater (P = 0.0096) and the microleakage significantly less (P = 0.0004) than to bovine dentin despite the fact that the restorative system penetrated more densely into bovine dentin. The use of bovine teeth instead of human teeth in these types of tests is not indicated.

A third generation dentinal bonding system, Tenure Solution dentin bonding system, has recently become commercially available. The original system has been modified twice. The objectives of this in vitro study were to determine the shear bond strengths of the three systems to dentin 15 minutes after specimen preparation, after 24 hours storage in physiological saline at 37 degrees C with and without temperature cycling, and after 4 weeks storage with and without temperature cycling. The shear bond strengths decreased with duration of storage but of each storage interval temperature cycling had no adverse effect on shear bond strength.

Summary The chemical treatment of enamel surfaces is an approach in obtaining increased bonding of dental materials to tooth surfaces. Three etching solutions commonly used at present are 50% H3PO4, 50% H3PO4 attenuated with 7% zinc oxide and 50% citric acid. The effects of these three conditioning solutions on normal and polished enamel surfaces and on the interfaces between untreated enamel and etched enamel surfaces were studied by scanning electron microscopy. The variable etching pattern observed with each of the acids made a comparative study difficult. This was further complicated by the dependence of the etching action on prism orientation on polished enamel surfaces. Additional factors that have to be considered are the presence of prismless enamel and perikymata. Surface profile recordings of polished and acid-etched polished enamel surfaces provided some quantitative measure of the etching action of the conditioning solutions. The 50% citric acid solution had the mildest etching action while 50% H3PO4 and 50% H3PO4 attenuated with 7% zinc oxide elicited comparable responses.

Microfilled composite resins have been introduced in clinical dentistry because of the difficulty in finishing conventional composite resins satisfactorily. Owing to the difference in coefficients of thermal expansion of the two resin systems, the objective of this in vitro study was to evaluate microleakage of a conventional and a microfilled composite resin. Class V cavities with butt cavosurface margins were prepared in the middle third of the facial surfaces of the crowns of 80 noncarious human premolar teeth; they were acid etched within the preparations only. Forty preparations were restored with Concise composite and forty with Silar microfilled resin. Ten teeth from each group were subjected to cyclic temperature changes between 5 and 55 degrees C for 1000, 2500, or 5000 cycles, respectively, and ten teeth from each group were not cycled (controls). After suitable preparation, the teeth were immersed in 45Ca solution for 18 h and contact radiographs were prepared. Microleakage was scored 0-3 at both the cervical and occlusal margins of the restorations. Microleakage was significantly greater at the cervical margins than at the occlusal margins. Differences within occlusal and cervical microleakages among the two resins were not significant.

Epidemiological studies have shown a positive association between selenium intake and dental caries. The purpose of this study was to determine quantitatively the selenium content of normal human enamel in a racial group with low caries prevalence. Each enamel sample was simultaneously irradiated with a reference standard containing 1 μg of selenium. The irradiations were done for three weeks in a nuclear reactor in a thermal neutron flux of 2 × 1013n cm−2 sec−1. After a cooling period of 3 weeks these samples were dissolved and quantitatively transferred, with selenium carrier, to a distillation apparatus. A selective distillation was carried out and each distillate made up to 25 ml and transferred to a standard plastic container. The gamma-ray activity of 75Se was measured with a 50cm3 coaxial Ge(Li) detector coupled to a fully transistorized 4000-channel analyser. The data were recorded on magnetic tape and afterwards computer-processed. The distillation technique gave a 98 per cent yield of selenium, which makes the method experimentally acceptable. The selenium content of the composite enamel samples was 0.08 ± 0.03 ppm.

A system using acidulated phosphate-fluoride solution (APF) was studied for the topical application of fluoride on acid-conditioned teeth and then coating with a cyanoacrylate varnish. Enamel biopsies for fluoride determination were taken from the six anterior teeth in both arches of 23 subjects, aged 19–23 years. The teeth were acid-conditioned and APF applied. The upper left and lower right segments were varnished while the contralatcral segments were left as controls. The teeth were re-biopsied in groups at 1, 2, 4, 12, 24 and 52 week intervals. At all intervals, fluoride levels after treatment were significantly higher (p < 0.001) regardless of whether they had been coated or not than those before treatment. There was no significant difference between coated and control teeth. When all the data were pooled, however, a significantly greater (p < 0.05) fluoride retention was found in the coated teeth.

1. The effects of frozen irradiated homogenous bone grafts on the healing of circumscribed defects in the mandibles and femora of forty albino rats have been studied. 2. The grafts were well tolerated by the host animals and did not appear in any way either to stimulate or to inhibit osteogenesis. The rate of healing of the defects containing the homografts compared favourably with that of the control defects.

A new composite restorative material, Enamelite, has recently been introduced for the conservative treatment of cervical erosion and hypoplastic enamel surfaces. The pulpal response elided by the restorative material was investigated in teeth of the vervet monkey and compared to a modified zinc oxide-eugenol cement. Buccal or labial Class V cavities were prepared in 128 teeth in six vervet monkeys. The teeth in contralateral segments were restored with the restorative and control materials, respectively. The experimental animals were killed at 4, 14 and 42 days. The restorative and control materials exhibited about the same minimal degree of cellular displacement and inflammatory response at each of the three postoperative time intervals. The percentage of specimens with reparative dentin increased progressively with time. At all three intervals the restorative material elicited a greater response than the control zinc oxide-eugenol cement. The results suggest that the clinical application of the restorative material on cervical eroded or hypoplastic enamel surfaces without a protective lining is a safe procedure.

The concentrations of magnesium, sodium, chlorine, aluminum, and calcium in pooled human dental calculus dried to constant weight at 105 C were determined by instrumental neutron activation analysis. Their mean concentrations were 0.50 ± 0.04%, 0.37 ± 0.03%, 0.09 ± 0.01%, 96.08 ± 14.63 ppm, and 28.04 ± 1.70%, respectively.

The sample to be analysed and a standard of known composition were irradiated simultaneously and the induced radioactivity compared. The investigation was done with high resolution Ge (Li) detectors coupled to fully transistorized 400 and 4000 channel analysers. By varying the irradiation time and conditions, it was possible to employ a non-destructive analytical procedure. The concentration of 16 elements, namely, Mg, Na, Cl, Al, Ca, Cr, Ba, Sb, Ag, Zn, Co, Fe, Sr, Au, Br and Mn was determined in normal human enamel and dentine by instrumental activation analysis.

The sample to be analysed, and a standard of known composition, were irradiated simultaneously in the poolside facility of a nuclear reactor for 130 hours in a thermal neutron flux of approximately 2×1013 n.cm−2. sec−1, and the induced radioactivity compared after a cooling period of four weeks. The investigation was done with a high resolution Ge(Li) detector coupled to a fully transistorized 4000 channel analyser. The concentration of five elements, namely Sb, Ag, Zn, Co and Fe, was determined in human dental calculus by instrumental activation analysis and found to be 0,68 ppm, 0,18 ppm, 174 ppm, 0,08 ppm and 54 ppm respectively.

Summary Conditioning of the enamel surface is an accepted procedure in several disciplines of dentistry to obtain increased bonding of dental materials to tooth surfaces. Three etching solutions commonly in use are 50% phosphoric acid, 50% phosphoric acid attenuated with 7% zinc oxide by weight and 50% citric acid. The effects of these solutions on the contact angle of an uncured epoxy resin on, and the bond strength of an epoxy resin formulation to polished enamel surfaces were investigated and compared with the results obtained on polished, unconditioned surfaces. In addition, the rates of etching of enamel surfaces by these acids were determined. The attenuated phosphoric acid produced the greatest reduction in contact angles and the most marked increase in bond strengths. 50% phosphoric acid etched the enamel surface to a greater extent than the other conditioning solutions.

The object of the present study was an attempt to relate fluoride concentration in enamel, caries experience, and the degree of fluorosis in a community residing in an area with a high level of fluoride. A significant difference was found between the male and female samples for the F and D parameters. A positive correlation was established for the male participants between DEGF and F, and a negative correlation between age and F. These correlations were not found for the female participants. Because of the low and narrow range of DMFT indexes, no correlation involving this parameter could be established.

It is suggested that decalcification occurring beneath orthodontic bands is, among other factors, related to the tensile bond strength of the cement to the enamel surface, its marginal leakage at the enamel-cement interface, and its solubility and and disintegration. Under the laboratory conditions described in this study the composite cement exhibited the greatest tensile bond strength to both enamel and band material. The composite cement also displayed no marginal leakage at the enamel-cement interface and showed no solubility or disintegration under the experimental conditions. It could therefore be anticipated that, of the four cements evaluated in this study, the composite cement would have the greatest potential for eliminating pathologic enamel decalcification occurring beneath orthodontic bands.

The finishing of enamel surfaces after removal of directly bonded attachments is essential. The following procedures are suggested: 1. The bonding of mesh-backed stainless steel brackets with a lightly filled resin system. 2. Debonding of attachments with a direct bonding bracket remover. 3. Removal of the bulk of the remaining resin with a 12-bladed tungsten carbide bur operated at high speed with adequate air cooling. 4. Finishing of the residual resin and underlying enamel with graded polishing discs or Ceramisté wheels used with light pressure and adequate air cooling. 5. Final finishing with a rubber cup and a water slurry of pumice.

Dental caries and sugar intake in South African pupils of 16 to 17 years in four ethnic groups

Summary Phosphoric acid at different concentrations has been extensively used as an etching agent to improve bonding of dental materials to enamel surfaces. Recently attention has been drawn to the possible use of polyfunctional organic acids as conditioning agents. The object of this investigation was to determine the optimal concentration of pyruvic acid as an etching agent. A commercial composite resin with an intermediary bonding system supplied with 37% H3PO4 as an etching agent was used as the control system. In addition, a comparative study was carried out to evaluate 37% H3PO4, 20% lactic acid and the optimal concentration of pyruvic acid as conditioning solutions. Etching enamel surfaces with 10% pyruvic acid resulted in the optimal tensile bond strength of the resin to etched enamel surfaces. The use of 10% pyruvic acid did not adversely affect the bond strength of the resin system when compared to enamel surfaces etched with 37% H3PO4 for the same time period. Significantly lower tensile bond strengths were recorded on enamel surfaces etched with 20% lactic acid. The rate and depth of etching obtained with 37% H3PO4 can be considerably reduced by using 10% pyruvic acid as the conditioning agent.