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Tooth bleaching (whitening) is one of the most common and inexpensive method for treating discolouration of teeth. Dental aesthetics, especially tooth colour, is of great importance to majority of the people; and discolouration of even a single tooth can negatively influence the quality of life. Therefore, a review of the literature was carried out (limited to aesthetic tooth-bleaching) to provide a broad overview of the efficacy and adverse effects of various tooth whitening products on soft and hard oral tissues.

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The purpose of this study was to evaluate the efficacy of two different 10% carbamide peroxide bleaching products just after treatment and after a 6-month follow-up period. Methods. Two 10% carbamide peroxide products (Opalescence PF and Nite White ACP) were applied nightly for 14 days, according to the manufacturers' instructions. The color of teeth 11 and 21 of thirty-four subjects having A2 or darker teeth were measured with a spectrophotometer (L(∗); a(∗); b(∗)) before treatment, just after treatment (14 days) and after 6 months. Results and Conclusions. Both products produced significant whitening of teeth with total color change (ΔE(ab) (∗)) of approximately 5.20 units. There was a significant improvement in all 3 color coordinates (L*, a*, and b(∗)) for up to 6 months postbleaching (P < .05). Nite White showed a higher degree of relapse (27%) than Opalescence (18%) over the 6-month period. It is suggested that rebleaching after 6 months is not necessary.

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This field study included the whole population of children aged 10-15 years (77 from a 0.19 mg/L F area; 89 from a 3.00 mg/L F area), with similar nutritional, dietary habits and similar ethnic and socioeconomic status. The fluoride concentration in the drinking water, the bone mineral content, the bone density and the degree of dental fluorosis were determined. The left radius was measured for bone width, bone mineral content, and bone mineral density. The mean fluorosis score was 1.3 in the low fluoride area and 3,6 in the high fluoride area. More than half the children in the low fluoride area had no fluorosis (scores 0 and 1) while only 5% in the high fluoride area had none. Severe fluorosis (30%) was only observed in the high fluoride area. The Wilcoxon Rank Sum Test indicated that fluorosis levels differed significantly (p < 0.05) between the two areas. No relationships were found between dental fluorosis and bone width or between fluorosis and bone mineral density in the two areas (Spearment Rank correlations). A significant increase in bone width was found with age but no differences amongst and boys and girls. A significant positive correlation was found in the high fluoride area between bone mineral density over age. In the 12-13 and 13-14 year age groups in the high fluoride area, girls had higher bone mineral densities. However, a significant negative correlation (p<0.02) was found for the low fluoride area (0.19 mg/L F) over age.

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OBJECTIVES: The purpose was to evaluate the effect of various Opalescence tooth-whitening products on enamel. METHODS AND MATERIALS: Enamel blocks were exposed to Opalescence PF 10% Carbamide Peroxide (n = 10), Opalescence PF 20% Carbamide Peroxide (n = 10), Opalescence Trèswhite Supreme 10% Hydrogen Peroxide (n = 10) and Opalescence Quick PF 45% Carbamide Peroxide (n = 10) according to the manufacturer's instructions. The control group was enamel blocks (n = 10) kept in artificial saliva. The values were obtained before exposure and after the 14-days treatment period. Enamel blocks were kept in saliva between treatments. Indent marks on enamel blocks were examined using the scanning electron microscope for treatment effects. RESULTS: All four different Opalescence products damaged enamel. The most damage was done when treated for a long period (112 hours). SEM images also showed damage to enamel by all 4 products. Opalescence with 10% and with 20% Carbamide Peroxide showed the highest damage, which also differed significantly (p < 0.05) from the saliva control group (p < 0.05; Tukey-Kramer Multiple comparison test). CONCLUSION: All 4 Opalescence products damaged enamel. Higher damage was done by the 10% carbamide peroxide and 20% carbamide peroxide products because of the much longer exposure period (112 hours in comparison to 7 hours).

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UNLABELLED: This study compared the microleakages in enamel and dentine of newly developed bonding systems from different manufacturers. Fifteen or more extracted non-carious human premolars were used for each dental material system. The bonding systems were used with their respective composites. Cylindrical cavities were prepared in enamel (scored as a separate entity 0-3) and cementum/dentine (scored 0-4) on the buccal surface at the cemento-enamel junction and restored. The specimens were thermocycled, cut into slices and the depth of dye penetration scored. For enamel, the microleakage values of Clearfil Protect Bond (CPB; median = 1.0) and Xeno III (2.3) did not differ statistically (p > 0.05, Chi-square test), while the microleakage of CPB (1.0) was significantly better than that of GC Unifil Bond (GC; 3.0), Prime & Bond XP (P & B; 3.0) and Adper Prompt L-Pop (APL; 3.0), p < 0.05. At the cementum/dentine side significantly (p < 0.05) more microleakage for CPB (2.0) was found than for GC (0.0), P&B (0.5), APL (0.5), and Xeno III (0.5). CONCLUSION: Enamel was most effectively sealed by CPB and cementum/dentine by GC, P&B, APL and Xeno III. The chemical composition perse did not seem to determine the amount and location of microleakage.

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UNLABELLED: Saliva contamination is a major clinical problem during restorative dental treatment. Restorative systems must possess sufficient marginal sealing ability to avoid microleakage. PURPOSE: The purpose of this study was to investigate the effect of saliva contamination on the microleakage of cavities restored with Prime & Bond NT and Dyract-AP. METHOD: Cavities were prepared with occlusal margins in enamel and gingival margins in dentine on the buccal surfaces of extracted human permanent premolar teeth. The cavities were etched with phosphoric acid or a non rinse conditioner (NRC). Preparations were distributed randomly into 4 treatment groups (N = 18) consisting of two respective etching methods (phosphoric acid/NRC), each with and without saliva contamination. After the restorative process the samples were thermocycled in dye, sectioned, and scored for microleakage. RESULTS: Contamination with saliva had no significant effect on microleakage on the enamel or dentine sides where phosphoric acid was used as conditioner. Where NRC was used, significantly more microleakage was observed at the enamel sides, but significantly less at the dentine sides.

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STATEMENT OF PROBLEM: Polymerisation shrinkage is a critical limitation of dental resins and may contribute to micro leakage. PURPOSE: The purpose of this study is to record and compare volumetric changes of various dental composites and compomers, exposed for 40 seconds to a commercial halogen light source. MATERIAL AND METHODS: Eleven light-polymerised composites and compomers were evaluated using a dilatometer that recorded the polymerisation shrinkage every 0.5 second. The mercury column pressure was measured electronically with a pressure-sensitive transducer, and the data recorded and stored in a computer. The computer also recorded the temperature, controlled the light-source and displayed the data in graphic format. Every material was tested ten times. The data were analysed by means of an ANOVA (P < 0.05). RESULTS: A high rate of shrinkage occurred for all materials in the first ten seconds of polymerisation. Surefil showed the lowest rate while TPH displayed the highest. Of the higher filled materials, Surefil (0.96%) showed the least shrinkage, followed by Z250 (0.99%), Dyract AP (1.18%), Herculite (1.27%), Compoglass (1.32%), Amelogen (1.34%) and TPH-Spectrum (1.6%). Overall, the flowable materials exhibited significantly more shrinkage (P < 0.05). For this group Compoglass Flow (2.3%) showed the least shrinkage followed by Filtec Flow (2.31%). Permaflo (3.6%) exhibited the most shrinkage followed by Dyract Flow (3%). CONCLUSION: Within the limitations of this study, it is concluded that significant differences exist among the polymerisation shrinkage of the most resins tested. An increase in the filler content of a material significantly lessens the polymerisation shrinkage while an increase in the monomer concentration causes significantly more polymerisation shrinkage. CLINICAL SIGNIFICANCE: The more flowable a composite material becomes, the more the restoration will shrink. Clinicians should take this into account when they decide on cavity design and materials to use.

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Forces developing during polymerisation of dental resins cause tension in the material to increase, with possible subsequent distortion of the bond. This study was undertaken to determine and compare polymerisation shrinkage in four different light-cured dental resins. A modified dilatometer was used to determine volumetric changes during polymerisation in 60 seconds of Z250 and Filtec flow from 3 M, and DyractAP and Dyract from Dentsply. Statistical analysis revealed that Dyract Flow shrinks significantly more (P < 0.05) during polymerisation in the first, as well as the last 10 seconds when compared with the other three materials and Z250 significantly less. An increase in the amount of fillers in the composition of the material leads to a decrease in polymerisation shrinkage, while an increase in the monomer concentration gives rise to more shrinkage. Stress, that builds up during the polymerisation process, is reduced by the elasticity of the material. The shrinkage of the flowables is therefore counteracted by their reduced rigidity.

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This-study was undertaken to evaluate and compare microleakage in class V cavities in human teeth which were lined with Amalgambond Plus with HPA (Parkell, USA), Optibond Solo (Kerr, U.S.A.), Fuji Plus (GC Corporation, Japan) and Prime & Bond 2.1 (Dentsply, Switzerland), and then restored with Logic amalgam (SDI Australia). The restored teeth were thermocycled in basic fuchsin dye, sectioned, and evaluated for dye penetration. The interdiffusion zones were viewed in a confocal laser scanning microscope (CLSM). The results showed that no bonding system could totally eliminate microleakage. Statistical analysis revealed significant differences between Amalgambond Plus with HPA and Prime & Bond 2.1, Fuji Plus as well as Optibond Solo, for both the enamel and dentine sides. No significant differences were found between Prime & Bond 2.1, Fuji Plus and Optibond Solo, for both the enamel and dentine sides. Amalgambond Plus showed significantly more leakage at dentine sides while Prime & Bond 2.1 showed significantly more leakage at enamel sides. The CLSM revealed hybrid layers of different thicknesses, resin penetration into tubules, as well as resin incorporation within the spherical particles of the amalgam. Optibond Solo, Fuji Plus and Prime & Bond 2.1 can serve to improve the marginal seal of amalgam restorations.

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Root fractures of posterior teeth, which are defined as fractures involving cementum, dentin, and pulp, are relatively uncommon among dental traumas. This study describes an unusual horizontal fracture of a mandibular second premolar. The tooth was asymptomatic and the fracture unnoticed until the crown broke off completely. The patient had no recollection of a causative event nor was there any evidence of previous physical trauma. The tooth was extracted, embedded in resin, sliced, and examined with different light microscopes. It was concluded that the tooth had been damaged previously but not to the extent that the pulp was seriously damaged. Resorption over a period of time eventually caused the final fracture.

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AIM: To evaluate and compare the in-vitro shear bond strength, microleakage and dentine-restorative interface of a self-etching/self-priming dentine bonding agent with a three-component dentine-bonding agent. METHOD: For shear bond strength (SBS) testing 30 non-carious human molars were used of which 15 were tested with Non-Rinse Conditioner (NRC)/Prime&Bond NT (PBNT) and Dyract AP and 15 were tested with Scotchbond Multi-Purpose Plus (SBMP) and F2000. For the microleakage evaluation cavity preparations were made on the facial surfaces of 30 non-carious human premolars of which 15 were restored with NRC and PBNT with Dyract AP and 15 were restored with SBMP and F2000. The dentine-restorative interface was examined through a confocal scanning laser microscope (CSLM). RESULTS: The mean SBS of PBNT and SBMP were 12.8 and 18.1 MPa, respectively. The microleakage scores showed NRC/PBNT leaked on the dentine side in 13 of the 15 specimens examined. On the enamel side two of the 15 specimens showed microleakage. With SBMP no microleakage was observed on either enamel or dentine sides. The CSLM images show clear resin tag and hybrid layer formation for both the materials examined although SBMP showed better and deeper penetration into the dentine with longer resin tags. SBMP showed resin tags measuring about 150 mm while the hybrid layer measured about 5 mm. The length of the resin tags as well as the thickness of the hybrid layer for PBNT were 20 mm Pounds and 2 mm Pounds, respectively. CONCLUSIONS: The acid-etch technique of SBMP produced higher bond strength and no microleakage when compared with the self-etching/self-priming 'non-rinse technique' of NRC with PBNT. Thus it can only be speculated that SBMP should be the superior in the clinical situation.

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OBJECTIVE: This study was undertaken to determine the relative shear bond strengths and microleakage of 4 bonding agents to dentin and amalgam and to investigate the bonding to dentin through confocal laser scanning microscopy. METHOD AND MATERIALS: Sixty noncarious molars were restored with 1 of 4 different systems, and the shear bond strengths were determined. For the microleakage study, Class V amalgam restorations were placed in 60 noncarious teeth. The specimens were thermocycled, the teeth were sectioned, and dye penetration was assessed. For confocal examinations, the first component of the bonding adhesives was labeled with rhodamine B. Each of the adhesives was applied to 3 dentin specimens, which were examined under a confocal laser scanning microscope RESULTS: Of the 4 restorative systems tested, AmalgamBond Plus + HPA and Prime & Bond 2.1/base-catalyst showed significantly higher shear bond strengths. Prime & Bond 2.1/base-catalyst had the lowest microleakage value, which was significantly lower than that of AmalgamBond Plus + HPA and AmalgamBond Plus. AmalgamBond Plus + HPA had the highest variation in both the bond strength and microleakage values. Confocal laser scanning microscopy revealed tag formation, penetration of the bonding agents deep into the tubules, and hybrid layer formation for all 4 bonding systems. CONCLUSION: The 2 best systems, Prime & Bond 2.1/base-catalyst and, to a lesser extent, AmalgamBond Plus + HPA, utilized a supplemental bonding agent.

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The composite resin, compomer and glass ionomer restorative materials used in modern dental practice are fire resistant and remain radiopaque. They shrink significantly and are likely to fall out of the cavities after being burnt, but they remain extremely important for identification purposes and it may be possible to identify the white filling materials used to restore teeth by their radiopacity and morphology. The radiographic density of these filling materials do not change significantly when exposed to heat and although they may be difficult to see with the naked eye, they will remain visible when radiographed. Furthermore, special care has to be taken when handling heated materials as their compressive strengths decrease significantly depending on temperature and time of exposure and damage is possible.

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The purpose of this study was to determine the relative microleakage of five restorative systems when bonded to dentine/cementum. For the microleakage determination Class V cavity preparations were prepared on the facial surfaces of 65 teeth (10-15 for each material) below the cemento-enamel junction and restored. The root apices were sealed, the teeth coated with nail varnish except for 1 mm surrounding the restorations and the specimens were thermocycled (x500) in 2 per cent methylene blue solution. Root sections including the restorations were dissolved in acid and the concentrations of the dye determined spectrophotometrically. The sequence of the microleakage values were: Dyract < OptiBond < AeliteBond < All-Bond 2 < ScotchBond. It is concluded that Dyract had the lowest microleakage at dentine/cementum interface, which may increase the longevity of the restorative in the clinical situation, with no, or less secondary caries.

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OBJECTIVE: The aim of this study was to determine, in vitro, the relative short- and long-term fluoride release from four resin-modified glass ionomers (Fuji II LC, Vitremer, Enforce & Advance), a polyacid-modified composite resin (Dyract compomer) and a bonding agent (OptiBond). METHODS: All the materials were prepared as outlined by the manufacturers. Circular discs of the materials mentioned were suspended in water for up to 300 days and the non-cumulative 24-h fluoride release was determined potentiometrically at chosen times. RESULTS: The amounts of fluoride released during the first day were Vitremer (1.46 micrograms mm-2), Advance (1.18 micrograms mm-2), Fuji (1.08 micrograms mm-2), Optibond (0.33 microgram mm-2), Dyract (0.31 microgram mm-2) and Enforce (0.15 microgram mm-2). After the second day the sequence changed slightly and remained approximately the same for the rest of the 300-day period. There was also an increase in the fluoride release during the 60-200-day period relative to the previous period. CONCLUSION: In general the most fluoride was released by Advance and not by Fuji II LC or Vitremer. For most materials, fluoride is still released after 300 days. Furthermore, even a thin layer of bonding agent released a relatively high amount of fluoride (volume-wise the most) at the beginning. It is deduced that even the release of relatively low amounts of fluoride may result in significant concentrations of fluoride in a microleakage gap.

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PURPOSE: To evaluate the shear bond strength (SBS) and microleakage (ML) to dentin as well as the antimicrobial action against five strains of oral bacteria of AElitebond single primer restorative system. MATERIALS AND METHODS: Fifteen molars were tested to failure for each of the four time periods: 15 minutes, 24 hours, 7 days and 30 days, after final cure. The test specimens were prepared on the dentin surfaces of the extracted molars ground on 600 grit SiC paper. The bonded cylinders were removed from the assembly apparatus after cure, stored in physiological saline at 37 degrees C for the four different time periods and subjected to a shear bond load at 0.5 mm/minute until fractured. For the microleakage determination, Class V cavity preparations were done on the facial surfaces of the roots of 15 canines below the cemento-enamel junction and the specimens thermocycled (500x) between 8 degrees C and 15 degrees C in 2% methylene blue. The teeth were cut into 6 mm thick sections and the sections which included the restorations were separately dissolved in acid. The color intensities of the dissolved sections were measured at a wavelength of 590 nm against a standard curve which was constructed from the dye. The modified model cavity method of Meryon & Johnson (1989) was used to assess the antimicrobial properties of the restorative system. RESULTS: The mean SBS values (in MPa) were found to be 10.3, 9.8, 11.47 and 9.9 after 15 minutes, 24 hours, 7 days, and 30 days, respectively. There was no significant increase (P < 5%) in the SBS after 15 minutes. The ML of 0.76 micrograms dye/ restoration was relatively low in comparison to the SBS values. The restorative system significantly (P < 5%) inhibited the growth of Actinomyces naeslundii with 88%, Streptococcus mutans with 42%, Streptococcus sanguis with 39% and Streptococcus oralis with 9%. However, the growth of Veillonella parvula was stimulated with 49%.

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We determined the relative shear bond strength (SBS) to dentine and cementum and the microleakage of All-Bond 2 universal dental adhesive and OptiBond multi-use filled adhesive. We found that for both systems the SBS increased significantly (p < 0.001) from 15 minutes to 24 hours and 7 days, but there was a slight significant (p < 0.001) weakening towards 30 days. At each time point the shear bond strength of All-Bond 2 and OptiBond were also compared and it was found that OptiBond had significantly higher values (p < 0.05) at all times except at 15 minutes. Optibond also had the lower value for the microleakage (p < 0.001). This study showed that OptiBond had significantly higher shear bond strengths to and lower microleakage in dentine which may increase the longevity of the material in the clinical situation.

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The objective of this study was to determine the rigidity of 11 different types (4 brands) of dental local anaesthetic injection needles available in South Africa. Twenty needles of each type were attached to a Zwick material testing apparatus and subjected to pressure testing. Stress vs deformation curves were obtained for each needle. The data obtained was logarithmically converted and subjected to an analysis of covariance. The results from this study showed that there were statistically significant differences in the rigidity of dental needles available on the South African market.

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The objective of this study was to determine the pressures that caused cartridge failure (leakage or fracture) of six different dental local anaesthetics available in South Africa. Forty glass cartridges of each local anaesthetic were placed in an apparatus and subjected to pressure testing using two different plungers. Failure of the cartridges was observed visually as well as on the computer screen of the testing apparatus. In addition the compressibility of local anaesthetic rubber stoppers (bungs) was measured. The data obtained was analysed by means of a two-way analysis of variance and a chi-square test. The results from this study showed that there were statistically significant differences in the mean pressures that caused failure of local anaesthetic cartridges available on the South African market.

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In previous studies the water fluoride content of the larger cities in South Africa, and smaller towns in the Cape Province were recorded. This project was extended to include smaller towns (500 or more inhabitants) in the Transvaal, Orange Free State and Natal. Drinking water was collected in polypropylene containers and the fluoride content determined potentiometrically. The information obtained made it possible to compile a table setting out the fluoride content of the drinking water in these smaller towns. The study confirms a previous observation that water from boreholes has the highest (p < 0.05), and fountains the lowest fluoride content.

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