Enamel Of Primary Teeth Research Articles

Neonatal lines in the enamel of primary teeth—A morphological and scanning electron microscopic investigation

Objective The neonatal line (NNL) is in principle found in all primary teeth and the line represents the time of birth. Earlier findings of the appearance of the NNL in light microscope and in microradiographs have shown not only changes in the prism direction of the enamel, but that the NNL has a hypomineralized character. Methods The neonatal line was analyzed in un-decalcified sections of primary lower and central incisors, collected from individuals of different ages utilizing polarized light microscopy, microradiography, scanning electron microscopy (SEM) and X-ray analysis (XRMA). Results In polarized light the NNL appeared to have a more porous structure than the enamel in general. The appearance of the NNL as a dark line in microradiographs is interpreted as the NNL being less mineralized than neighbouring enamel. Analysis with ImageJ visualized the reduction of the amount of grey value, indicating that the NNL is less mineralized. Analysis of the NNL in SEM showed a reduction of the diameter of enamel prisms, the more narrow diameters continued through the postnatal enamel. A change of the growth direction of the prisms was also observed at the NNL. In a three-dimensional image the NNL appeared as a grove, however, in non-etched enamel no grove was seen. The elemental analyses with XRMA showed no marked changes in the content of C, Ca, P, N, O or S in the area around the NNL. Conclusions The NNL is an optical phenomenon due to alterations in height, and degree of mineralization of the enamel prisms.

Prenatal nutrition and asthma: hope or hype?

David Barker’s “fetal origins” hypothesis has changed the way we think about the aetiology of adult onset diseases, such as coronary heart disease and type 2 diabetes.1 Underpinning the epidemiological...

Bond strength of adhesive systems to dentin and enamel—Human vs. bovine primary teeth in vitro

Objectives This in vitro study compared the bonding performance of four adhesive luting agents to dentin and enamel of human and bovine primary teeth, in order to evaluate the suitability of primary bovine hard tissues for replacement of those of human origin for bond testing. Methods A composite (Clearfil AP-X) was bonded to specimens from 167 extracted human ( n = 88) and bovine ( n = 88) primary teeth using the following adhesive systems: Syntac Assortment (SY), Adaper Prompt L-Pop (PLP), iBond Gluma inside (IB) and Clearfil Protect Bond (PB). After 24 h storage in distilled water, shear bond strength was determined according to ISO/TS 11405:2003. The data ( n = 11 per group) were statistically analyzed with the Mann–Whitney U-test and the error-rates method (ERM). The fracture modes were analyzed with the χ 2-test. Results Bond strength data (ERM) and fracture modes ( χ 2-test) using human primary teeth were, in general, not statistically different from those of bovine origin. With few exceptions, pair wise comparisons showed the same results. The bond strength data for SY, PLP and PB bonded to primary human and bovine enamel were higher than those to primary human and bovine dentin, for IB vice versa. Significance Bovine teeth may be considered as a suitable alternative to human teeth in bond strength tests for primary dentition.

Surface Morphology of Sound Deciduous Tooth Enamel after Application of a Photo-Absorbing Cream and Infrared Low-Level Laser Irradiation: Anin VitroScanning Electron Microscopy Study

The purpose of this descriptive scanning electron microscopic study was to characterize surface alterations in deciduous tooth enamel after in vitro infrared diode laser irradiation, using a photo-absorbing agent alone and also combined with fluoride, before and after laser irradiation. Previous investigations have demonstrated increased enamel caries resistance after laser irradiation. Seven extracted or exfoliated primary molar teeth underwent soft tissue débridement and fluoride-free prophylaxis. Buccal surfaces were determined to be caries free by macroscopic examination. Sample groups were divided into: (1) control (no treatment); (2) infrared diode laser irradiation (lambda = 810 nm, 68 nm, 60 mW/mm(2), 30 W) using the photo-absorbing agent alone (IRDL + PA; 500 J/cm(2)); and (3) infrared diode laser irradiation using a photo-absorbing agent combined with 2% fluoride (IRDL + PFA; 500 J/cm(2)). Buccal surfaces were evaluated following standard scanning electron microscopy preparation techniques. Control samples of enamel surfaces were relatively smooth but presented occasional enamel prism ends. There were no areas with cavitations or surface defects. After the IRDL + PA treatment, irradiated surfaces became rough and mildly to moderately irregular with scarce enamel cavitations and without exposure of enamel prism ends. The surfaces had adherent granules and only occasional fine cracks and porosities in surface coatings were noted. After the IRDL + PFA treatment, there was a homogenous confluent surface that masked typical enamel surface markings. The surfaces had well-defined globules resulting from the IRDL + PFA treatment, that were not seen after IRDL + PA treatment. Treatment of deciduous tooth enamel with infrared diode laser irradiation using a photo-absorbing agent and a photo-absorbing agent combined with 2% fluoride created surface coatings that may act as reservoirs for mineral phases during cariogenic activity on enamel, and also provide a certain degree of protection against cariogenic challenge.

Microtensile Bond Strength of Contemporary Adhesives to Primary Enamel and Dentin

The purpose of this study was to assess bond strength of three self-etching and two total-etch adhesive systems bonded to primary tooth enamel and dentin. Forty extracted primary human molars were selected and abraded in order to create flat buccal enamel and occlusal dentin surfaces. Teeth were assigned to one of the adhesive systems: Adper Scotch Bond Multi Purpose, Adper Single Bond 2, Adper Prompt L-Pop, Clearfil SE Bond and AdheSE. Immediately to adhesive application, a composite resin (Filtek Z250) block was built up. After 3 months of water storage, each sample was sequentially sectioned in order to obtain sticks with a square cross-sectional area of about 0.72 mm2. The specimens were fixed lengthways to a microtensile device and tested using a universal testing machine with a 50-N load cell at a crosshead speed of 0.5 mm/min. Microtensile bond strength values were recorded in MPa and compared by Analysis of Variance and the post hoc Tukey test (a = 0.05). In enamel, Clearfil SE Bond presented the highest values, followed by Adper Single Bond 2, AdheSE and Adper Scotch Bond Multi Purpose, without significant difference. The highest values in dentin were obtained with Adper Scotch Bond Multi Purpose and all other adhesives did not present significant different values from that, except Adper Prompt L-Pop that achieved the lowest bond strength in both substrates. Adper Scotch Bond Multi Purpose and Adper Single Bond 2 presented significantly lower values in enamel than in dentin although all other adhesives presented similar results in both substrates. contemporary adhesive systems present similar behaviors when bonded to primary teeth, with the exception of the one-step self-etching system; and self-etching systems can achieve bond strength values as good in enamel as in dentin of primary teeth.

Chemical composition of enamel and dentine in primary teeth in children from Thailand exposed to lead

Enamel and dentine in teeth of children with high blood levels of lead were analyzed by means of secondary ion mass spectrometry (SIMS) and X-ray micro-analyses (XRMA) and compare with teeth from children with low blood levels of lead. The SIMS analysis revealed detectable levels of Pb in dentine close to the pulp. The XRMA analyses could not detect any lead. There were no differences found in lead level in enamel of high lead level exposed teeth from low level exposed. The results confirm that children with high blood levels of lead have an uptake of lead in dentine close to the pulp.

Analysis of Photoreflectance and Microhardness of the Enamel in Primary Teeth Submitted to Different Bleaching Agents

Treatment of darkened teeth in children is of great importance from an esthetic-functional point of view and for the psychoemotional development of the child. The objective of the present study was to determine the in vitro efficacy of three bleaching agents for whitening of artificially stained primary teeth. Fifty anterior primary teeth were artificially stained and then divided into three experimental groups (n = 15) submitted to bleaching treatment with 35% hydrogen peroxide gel, 35% carbamide peroxide gel, and 35% carbamide peroxide gel mixed with sodium perborate powder. The control group (n = 5) was not submitted to any bleaching treatment. Color changes were evaluated with a reflectance spectrophotometer and possible alterations in the enamel surface after bleaching were measured by Vickers microhardness testing. The data were assessed using the Student's t test. The results confirmed the bleaching action of the three agents tested. No significant difference in mean microhardness was observed between the three bleaching agents when compared to the control group.

External exposure of deciduous tooth enamel to photons: dose conversion coefficients for standard radiation fields

Dose conversion coefficients for teeth of children were computed for external photon sources by means of Monte Carlo methods using a modified MIRD-type mathematical phantom of a 5-year-old child. The tooth region is separated into eight smaller regions that represent incisors, canines, first and second molars. Each of these sub-regions is separated into enamel and dentin parts. Dose conversion coefficients were computed as ratio of absorbed dose in the enamel and air kerma. They are given for unidirectional (AP, PA, RLAT, LLAT), rotational (ROT) and isotropic (ISO) photon sources in the energy range from 10 keV to 10 MeV. All computations were performed with the MCNP4 code including coupled electron-photon transport. The computed coefficients demonstrate a significant non-linearity versus photon energy, which is more pronounced than that observed for adult phantoms. Due to this non-linearity, use of the EPR-measured doses in human teeth requires information on the incident photon fluence spectra. The data presented can be used for assessment of public exposure.

Lead contents in the surface enamel of deciduous teeth sampled in vivo from children in uncontaminated and in lead-contaminated areas

This study aimed to: (1) measure lead contents in the surface enamel of two populations consisting of 4–6-year-old children, one from an apparently uncontaminated area (Ribeirão Preto, São Paulo State, SP, Brazil, n=247) and the other from an area notoriously contaminated with lead (Bauru, São Paulo State, Brazil, n=26); (2) compare biopsy depths between the two populations; (3) correlate biopsy depth with lead content; (4) stratify samples according to biopsy depth to compare lead contents in samples from similar biopsy depths. A surface enamel acid-etch microbiopsy was performed in vivo on a single upper deciduous incisor for each sample. Lead was measured by graphite furnace atomic absorption spectrometry (GFAAS) while phosphorus was measured colorimetrically to establish biopsy depth. Samples from both populations were classified into categories of similar biopsy depths based on biopsy depth quartiles. Median lead contents were statistically different between the Ribeirão Preto population (206 μg/g, range: 5–1399 μg/g) and the Bauru population (786 μg/g, range: 320–4711 μg/g) ( p<0.001); however, biopsy depth did not differ between the Ribeirão Preto (3.9 μm, Standard Deviation, SD=0.9) and Bauru (3.8 μm, SD=0.9) populations ( p=0.7940). Pearson's correlation coefficient for biopsy depths versus log 10 lead values was −0.29 for Ribeirão Preto and −0.18 for Bauru. Lead contents were statistically different between the two populations for all quartiles of biopsy depth. These findings suggest that lead accumulated in the surface enamel of deciduous teeth is linked to the environment in which people reside, indicating that this tissue should be further explored as an accessible biomarker of lead exposure.

The use of micro‐Raman spectroscopy to differentiate between sound and eroded primary enamel

The aim of this study was to investigate differences in phosphate group concentration between areas of sound and eroded enamel in primary teeth using micro-Raman spectroscopy (MRS). The Raman spectroscopic technique enables researchers to obtain information about molecules by analysing scattered light caused by monochromatic laser excitation. Ten extracted anterior primary teeth with areas of sound and eroded enamel were used. Three, 10-s scans were carried out at three points along a 3-microm linear area in both sound and eroded primary enamel, and Raman spectra were obtained with the LabRam 300 fitted with an Olympus BX40 microscope. Scanning electron microscopy was used to confirm the presence of sound and eroded enamel on each tooth. The phosphate nu(1) band was located between 958.5 and 967.0 cm(-1). There was no statistically significant difference between the area under the phosphate nu(1) band values for the eroded and sound areas (P = 0.7302). Scanning electron microscopy confirmed the presence of sound and eroded areas on all specimens. In this study, there was no statistically significant difference found between phosphate group concentration in eroded and sound primary enamel when analysed by MRS.

Estimation of trace elements in sound and carious enamel of primary and permanent teeth by atomic absorption spectrophotometry: An in vitro study

The influence of trace elements on the prevalence of caries is a complex subject. However, the demonstration of an inverse relationship between caries prevalence and fluoride (F) intake indicates the potential effect of trace elements on caries. This in vitro study sought to estimate and compare the trace element concentrations in sound and carious enamel of primary and permanent teeth. Forty sound and carious primary and permanent teeth, extracted from children and adolescents of Davangere city, were collected. The teeth were divided into four groups (of ten each) and enamel samples were prepared by mechanical grinding. The trace elements were estimated using atomic absorption spectrophotometer. The results of our study showed the presence of 18 trace elements (F, Sr, K, Al, Si, Ni, B, Fe, Cu, Mn, Co, Cr, Zn, Mg, Se, Pb, Mo, and V) in the enamel of sound and carious primary and permanent teeth. The mean, standard deviation, and range (at 95% confidence level) were calculated for each element. The concentrations of F, Sr, and K were significantly ( P <0.05) higher in sound enamel of permanent teeth than in sound enamel of primary teeth. The concentrations of F, Sr, K, Al, and Fe were significantly ( P <0.05) higher in sound enamel of permanent teeth than in carious enamel of permanent teeth. The concentrations of F, K, and Si were significantly ( P <0.05) higher in sound enamel of primary teeth than in carious enamel of primary teeth.

An in vitro comparison of short and long term shear bond strengths of polyacid modified composite resins to primary human and bovine enamel and dentine

This in vitro study compared the shear bond strengths and fracture patterns over 7 and 180 day periods of two PMCRs bonded to both human and bovine primary tooth enamel and dentine to determine if the bovine tooth model is a suitable substitute for the human tooth model. Flattened enamel and dentine surfaces were produced using water irrigated #600 grit SiC paper and the teeth randomly placed in groups of N=10. Cylinders of Dyrat AP (Dentsply/DeTrey) or F2000 (3M/ESPE) were bonded to the surfaces that were either etched with 37% H(3)PO(4) (etch, E groups) or treated with their respective conditioners, primers and adhesives (no etch, NE groups). The teeth were stored in distilled water at 37(o)C and shear bond strength (SBS) tested to failure at either 7 (human and bovine) or 180 days (bovine). The modes of failure were assessed under a dissecting microscope at x30. In general the results showed comparable mean SBS for both human and bovine enamel with Dyract AP, E and NE and also for F2000, E. Lower enamel SBS were recorded for F2000 NE but there was no significant differences in mean SBS for bovine enamel after long term storage. For dentine, significantly larger SBS were recorded for human versus bovine teeth for all of the four bonding protocols. There were also significant species differences, the mean SBS for Dyract AP, E and F2000, E for human dentine were higher than bovine but the mean SBS for the respective NE groups showed no significant differences between species. It was concluded that 37% H(3)PO(4) has a detrimental effect on SBS for bovine dentine. Over long term storage SBS of bovine dentine bonds decreased. The modes of failure were related to SBS with varying degrees of significance. Bovine primary incisor enamel and dentine, provided the latter is not conditioned with 37% H(3)PO(4), are suitable alternative test SBS substrates for human enamel and dentine.

Qualitative and quantitative evaluation of enamel after various stripping methods

In this study, we investigated ultramorphology, surface roughness, and microhardness of permanent and deciduous tooth enamel after various stripping methods. One hundred twenty deciduous and permanent teeth (n = 60 each) were used. Qualitative (scanning electron microscopy) and quantitative (surface roughness and microhardness tests) experiments were carried out in the following experimental groups: group 1, stripping disk; group 2, diamond-coated metal strip; group 3, stripping disk and Sof-Lex discs (3M-ESPE, Seefeld, Germany); group 4, diamond-coated metal strip and Sof-Lex discs; group 5 (chemical stripping), 37% orthophosphoric acid in conjunction with diamond-coated metal strip; group 6 (control), no stripping. Surface roughness values (Ra) for permanent and deciduous enamel were evaluated with Welch analysis of variance (ANOVA) and Tamhane tests, and Kruskal-Wallis and Mann-Whitney tests, respectively. Microhardness values were evaluated statistically with Kruskal-Wallis, 1-way ANOVA, and Duncan tests. Deciduous and permanent teeth showed similar results in terms of surface roughness and surface morphology. Groups 3 and 4 had the smoothest deciduous and permanent enamel surfaces, whereas chemical stripping (group 5) produced the roughest surfaces in both enamel types. Stripping did not lead to a significant change in the microhardness of permanent enamel. All stripping methods significantly roughened the enamel surfaces. Polishing the stripped surface with Sof-Lex discs decreased the roughness.

Comparative ablation rate from a Er: YAG laser on enamel and dentin of primary and permanent teeth

This study was conducted to analyze the ablation rate and micromorphological aspects of microcavities in enamel and dentin of primary and permanent teeth using a Er: YAG laser system. Micromorphological evaluation has been performed in terms of permanent teeth; however, little information about Er: YAG laser interaction with primary teeth can be found in the literature. Because children have been the most beneficiary patients with laser therapy in our offices, it is extremely necessary to compare the effects of this kind of laser system on the enamel and dentin of permanent and primary teeth. In this study, we used eleven intact primary anterior exfoliated teeth and six extracted permanent molar teeth. We used a commercial laser system: a Er: YAG Twin Light laser system (Fotona Medical Lasers, Slovenia) at 2940 nm, changing average energy levels per pulse (100, 200, 300, and 400 mJ) producing 48 microcavities in enamel and dentin of primary and permanent teeth. Primary teeth are more easily ablated than are permanent teeth, when related to enamel or dentin. However, while this laser system is capable of slowly revealing the enamel’s microstructure, in dentin only the lowest laser energies permit this kind of observation, more easily decomposing the original tissue aspect, when related to primary or permanent teeth. Statistically, the only different factor at the 5% level was an energy per pulse of 400 mJ, confirming the results found in SEM. Our results showed that dentin in both primary and permanent teeth is less resistant to Er: YAG laser ablation; this fact is easily observed under SEM observation and through the ablation rate evaluation.

In vitro caries formation in primary tooth enamel: Role of argon laser irradiation and remineralizing solution treatment

The authors evaluated the effects of argon laser (AL) diation and remineralizing solution (RS) treatment alone and in combination on carieslike lesion formation in primary tooth enamel in an in vitro study. The authors divided 10 caries free primary tooth enamel surfaces into four segments and assigned them to one of four treatment groups: no treatment control, AL irradiation alone at 13.5 joules per square centimeters (0.270 watts, 5-millimeter beam, 10 seconds), RS treatment alone for two minutes and AL irradiation before RS treatment. The authors created in vitro caries using a modified ten Cate solution. They evaluated longitudinal sections (three per tooth segment, 30 per treatment group) for mean lesion depth. After lesion formation, mean lesion depths (+/- standard deviation) were 179 +/- 16 micrometers for the no treatment controls, 137 +/- 19 microm for AL irradiation alone, 87 +/- 9 microm for RS treatment alone and 68 +/- 12 microm for AL irradiation before RS treatment. All treatment groups had mean lesion depths that were significantly less than those for the matched no-treatment control group (analysis of variance [ANOVA], Duncan multiple range [DMR] test, P < .05). AL irradiation before RS treatment significantly reduced lesion depth compared with AL irradiation alone or RS treatment alone (ANOVA, DMR test, P < .05). The maximum reduction in lesion depth in primary tooth enamel was achieved when the RS--which contained calcium, phosphate and fluoride in a carbopol base--was combined with AL irradiation. It would appear that to improve clinical caries resistance to enamel dissolution, AL irradiation before RS treatment could be used.

Complementary Physical and Mechanical Techniques to Characterise Tooth: A Bone-like Tissue

Bone like tissues are biocomposites comprising an organic matrix (mostly collagen) and a reinforcement phase in the form of mineral crystals (poorly stoichiometric apatite). The composite properties are a result of the material characteristics of the two phases, their interaction, the relative composition, the orientation and the micro-architecture of the structure. The inherent spatial heterogeneity of these tissues (a result of evolutionary and functional requirements) and their exposure to various environmental and mechanical influences result in highly variable properties on the microscale, which can only be characterised by modern microanalytical methods. We present here results obtained by the complementary use of the modern nanoindentation and micro-X-ray diffraction techniques, which were used to probe the properties and structure of human dentine and enamel of primary molar teeth. The results show that both the addition and the higher organization of mineral within the organic matrix produce stiffer and harder tissue and that the examination of properties within small tissue volumes can be reliably achieved by use of these two methods in parallel. This opens new avenues in the study of biomaterial in general, and for the local characterisation of regions of teeth that suffered bacterial attack, mechanical wear, fluoridisation, chemical bleaching, or dental treatment such as laser ablation or drilling.

Complementary physical and mechanical techniques to characterise tooth: a bone-like tissue

Bone like tissues are biocomposites comprising an organic matrix (mostly collagen) and a reinforcement phase in the form of mineral crystals (poorly stoichiometric apatite). The composite properties are a result of the material characteristics of the two phases, their interaction, the relative composition, the orientation and the micro-architecture of the structure. The inherent spatial heterogeneity of these tissues (a result of evolutionary and functional requirements) and their exposure to various environmental and mechanical influences result in highly variable properties on the microscale, which can only be characterised by modern microanalytical methods. We present here results obtained by the complementary use of the modern nanoindentation and micro-X-ray diffraction techniques, which were used to probe the properties and structure of human dentine and enamel of primary molar teeth. The results show that both the addition and the higher organization of mineral within the organic matrix produce stiffer and harder tissue and that the examination of properties within small tissue volumes can be reliably achieved by use of these two methods in parallel. This opens new avenues in the study of biomaterial in general, and for the local characterisation of regions of teeth that suffered bacterial attack, mechanical wear, fluoridisation, chemical bleaching, or dental treatment such as laser ablation or drilling.

Fluoride Concentrations in Enamel and Dentin of Primary Teeth after Pre- and Postnatal Fluoride Exposure

The aim of this study was to determine any existing difference in the amount of fluoride incorporated in the surface, body enamel and dentin of two groups of deciduous teeth, either exposed to pre- and postnatal fluoride supplements or to postnatal fluoride only. One hundred and eighty five subjects with intact deciduous incisors were selected from a randomized, double blind study of the caries preventive efficacy of prenatal fluoride (F) supplementation. Surface and body enamel samples were obtained by the acid etch biopsy technique. Dentin microsamples were obtained by drilling to a depth of 100 µm using the microdrill biopsy technique. It was concluded that fluoride exposure during the prenatal period offered no additional measurable fluoride uptake by dental tissues other than that attributable to postnatal fluoride alone.

Morphological appearance and chemical composition of enamel in primary teeth from patients with 22q11 deletion syndrome

Patients with 22q11 deletion syndrome have many and complex medical problems, including hypocalcemia and/or hypoparathyroidism. Odontological findings include enamel aberrations in both dentitions. In order to describe enamel morphology, chemical composition in primary teeth, and to investigate the relationship between medical history and morphological appearance, dental enamel was investigated in 38 exfoliated primary teeth from 15 children and adolescents. Morphology was studied by the use of a polarized light microscope, microradiography, scanning electron microscopy, X-ray microanalysis, and secondary ion mass spectrometry. The morphological findings were compared with medical history. The teeth showed, in principle, a normal morphological appearance with regard to prism structure. A high frequency of aberrations, such as hypomineralization, hypoplasia and extra incremental lines, were found. The majority of the aberrations were found around the neonatal line. There was a relationship between high numbers of medical problems in the patients and enamel deviations. The result supports the hypothesis of under-reporting of both hypocalcemia and hypoparathyroidism in patients with 22q11 deletion syndrome.

Bond strengths of eight contemporary adhesives to enamel and to dentine: an in vitro study on bovine primary teeth

The aim of this study was to compare the shear and tensile bond strengths of eight adhesive systems to the enamel and dentine of primary bovine teeth. Two hundred and fifty-six noncarious bovine mandibular primary incisors were collected and stored in an aqueous 1% chloramine solution at room temperature for no longer than 3 months after extraction. The tested adhesives were: Clearfil SE bond (SE); Adper Prompt L Pop (LP); Optibond Solo Plus Self-etch (OB); AdheSE (AS); Xeno III (XE); Scotch Bond 1 (SB); Etch & Prime 3.0 (EP); and I Bond (IB). For the shear bonding test and the tensile bonding test, the labial surfaces of primary incisors were used. To obtain a flat surface, the labial surfaces of the teeth were sanded on wet silicon carbide paper, first with number 200 grit for 20 s and then with number 600 grit for 60 s (n = 128; 64 for shear bonding and 64 for tensile bonding). The results were compared with an analysis of variance and Bonferroni's multiple comparison test. Shear bond strength values ranged from 18.1 to 8.9 MPa on enamel (in decreasing order, SE, LP, OB, AS, XE, SB, EP and IB), and from 17.8 to 8.2 MPa on dentine (in decreasing order, SE, SB, OB, AS, XE, LP, IB and EP). Tensile bond strength values ranged from 13.1 to 6.7 MPa on enamel (in decreasing order, SE, OB, AS, LP, XE, IB, SB and EP), and from 12.1 to 5.7 MPa on dentine (in deceasing order, SE, SB, OB, AS, XE, LP, IB and EP). The differences in bond strengths between the eight systems on enamel and dentine were all statistically significant. This was true for both the shear and tensile bond strengths. The highest shear bond strength was achieved by SE on enamel and dentine, and the lowest by IB on enamel and EP on dentine. The highest tensile bond strength was obtained by SE on enamel and dentine, and the lowest by EP. Shear bond strengths were significantly higher on enamel when compared to dentine for five of the eight adhesives systems, and tensile bond strengths were significantly higher on enamel when compared to dentine for all but two systems.