ZnO and antimonene-based surface plasmon resonance sensor for enamel, dentin, and cementum layer detection in human teeth

Radiodensity of enamel and dentin of human, bovine and swine teeth

Improvement of laser ablation in situ micro-analysis to identify diagenetic alteration and measure strontium isotope ratios in fossil human teeth

PURPOSEThe aim of this study was to evaluate the effect of tooth surface pre-treatment steps on shear bond strength, which is essential for understanding the adhesive cementation process.MATERIALS AND METHODSShear bond strengths of different cements with various tooth surface treatments (none, etching, priming, or etching and priming) on enamel and dentin of human teeth were measured using the Swiss shear test design. Three adhesives (Permaflo DC, Panavia F 2.0, and Panavia V5) and one self-adhesive cement (Panavia SA plus) were included in this study. The interface of the cement and the tooth surface with the different pre-treatments was analyzed using SEM. pH values of the cements and primers were measured.RESULTSThe highest bond strength values for all cements were achieved with etching and primer on enamel (25.6 ± 5.3 - 32.3 ± 10.4 MPa). On dentin, etching and priming produced the highest bond strength values for all cements (8.6 ± 2.9 - 11.7 ± 3.5 MPa) except for Panavia V5, which achieved significantly higher bond strengths when pre-treated with primer only (15.3 ± 4.1 MPa). Shear bond strength values were correlated with the micro-retentive surface topography of enamel and the tag length on dentin except for Panavia V5, which revealed the highest bond strength with primer application only without etching, resulting in short but sturdy tags.CONCLUSIONThe highest bond strength can be achieved for Panavia F 2.0, Permaflo DC, and Panavia SA plus when the tooth substrate is previously etched and the respective primer is applied. The new cement Panavia V5 displayed low technique-sensitivity and attained significantly higher adhesion of all tested cements to dentin when only primer was applied.

The article provides a brief overview of the studies regarding changes in the structure and composition of teeth after eruption. The factors of degenerative changes in tooth structures and their relationship with non-carious lesions have been analyzed. The study makes emphasis on the tooth durability and the factors influencing tissue fatigue, explaining increased tissue wear due to local factors. Understanding mechanisms of metabolism of teeth hard tissues is the key to the stability of restorative treatments and occurrence of non-carious tooth lesions. The evolution of views on this problem is noteworthy. The literature review reveals the initial predominance of mechanical actions, abrasion, and mineralization. It is later complemented by a detailed analysis of the influence of destructive stresses and deformation due to mechanical factors. All the leading works of the 2000s are dedicated to analyzing the ultrastructural features of enamel that affect its mechanical characteristics and can explain both the characteristics of the shape and intensity of mechanical tooth wear during the functioning of the stomatognathic system, as well as the durability of the performed restorations. The literature review covers 74 sources over the past 15 years.

There are few scientific approaches to human identification that are more effective than a well-trained forensic dentist armed with a set of high-quality dental records and radiographs. Fingerprinting is probably the only other technique used with greater frequency, but as we know, the soft tissue of the extremities does not resist the ravages of time and environment like the enamel and dentin of human teeth. So, in terms of rapidity, degree of certainty, cost-effectiveness, and applicability to a wide range of intact, decomposing, or skeletonized remains, forensic odontology has been the identification method of choice.1

Experimental Study on the Coefficient of Friction between the Enamel Surface, the Cut Surfaces of Enamel and Dentin of Human Teeth and the Surfaces of the Rolled and Precision Cast Plate of Dental Alloys.

During eating, the teeth usually endure the sharply temperature changes because of different foods. It is of importance to investigate the heat transfer and heat dissipation behavior of the dentino–enamel junction (DEJ) of human tooth since dentine and enamel have different thermophysical properties. The spatial and temporal temperature distributions on the enamel, dentine, and pulpal chamber of both the human tooth and its discontinuous boundaries, were measured using infrared thermography using a stepped temperature increase on the outer boundary of enamel crowns. The thermal diffusivities for enamel and dentine were deduced from the time dependent temperature change at the enamel and dentine layers. The thermal conductivities for enamel and dentine were calculated to be 0.81 Wm-1K-1 and 0.48 Wm-1K-1 respectively. The observed temperature discontinuities across the interfaces between enamel, dentine and pulp-chamber layers were due to the difference of thermal conductivities at interfaces rather than to the phase transformation. The temperature gradient distributes continuously across the enamel and dentine layers and their junction below a temperature of 42°C, whilst a negative thermal resistance is observed at interfaces above 42°C. These results suggest that the microstructure of the dentin-enamel junction (DEJ) junction play an important role in tooth heat transfer and protects the pulp from heat damage.

Microstructural and mechanical study of zirconia-hydroxyapatite (ZH) composite ceramics for biomedical applications

Proton-induced X-ray emission in the trace analysis of human tooth enamel and dentine

To investigate the relationship between the shear bond strength of resin adhesion on the enamel of human teeth and loading direction. Two kinds of dental resin adhesives [Group A (Clearfil SE BOND) and Group B (Prime&Bond NT)] were used to bond their responding resin composites to the enamel of human teeth respectively. The shear tests were performed from four directions: root apex direction, occlusion direction, mesial direction, and distal direction. The shear bond strength of the two resin adhesives on the enamel behaved in the same way, which was the root apex direction [(44.38 +/- 3.68) Pa and (45.50 +/- 2.88) Pa] > mesial direction [(37.81 +/- 7.56) Pa and (40.15 +/- 2.59) Pa] and distal direction [(35.71 +/- 3.34) Pa and (35.75 +/- 4.15) Pa] > occlusion direction [(29.19 +/- 3.75) Pa and (33.44 +/- 3.79) Pa], respectively. A significantly statistical difference in the shear bond strength values was found between the root apex direction and the occlusion direction (P < 0.05), and there was no statistical significant difference between the mesial and distal directions (P > 0.05). The shear bond strength between the human tooth enamel and the dental resin adhesives is related to the direction of the shearing force.

To determine the effect of water fluoride concentration on the fluoride profile across the entire thickness of the cementum and root dentine of human permanent anterior teeth in adults. Twenty-eight human permanent anterior teeth from individuals aged from 30 to over 60 years were studied. Teeth were obtained from a natural high-fluoride area (West Hartle-pool, UK; 1.0-1.3 ppm F in drinking water, WHP) and the other from a non-fluoridated naturally low fluoride area (Leeds, UK; 0.1 ppm F in drinking water, LDS). Cementum and root dentine were sampled using an abrasive micro-sampling technique from the cementum surface to the pulpal surface of root dentine. Fluoride concentration was higher in tooth roots (the cementum and dentine) taken from the naturally fluoridated area (WHP) than from the non-fluoridated area (LDS). Age and average fluoride concentration showed a positive correlation in WHP dentine, middle region of the root (r = 0.78, P < 0.001) and in the apical region of the root (r = 0.61, P < 0.05). WHP cementum had the strongest fluoride concentration correlation with age in the cervical region of the root (r = 0.67, P < 0.01). An analysis of variance (ANOVA) showed that the area (water fluoride content), age and number of years lived in the area combined with total age were significant. The fluoride content of cementum and root dentine in adult residents is related to fluoride content in drinking water.

Fluorine in Dentin and Enamel of Sound and Carious Human Teeth

Enamel and dentin of human teeth irradiated by CO2 laser were investigated by confocal laser scanning microscopy (CLSM), low vacuum scanning electron microscopy (WET-SEM) and atomic force microscopy (AFM). Optical tomographic imaging by CLSM, compositional imaging based on atomic number effect of reflected electrons by WET-SEM, high resolution observation of surface morphology by AFM were done for both the irradiated and non-irradiated area of the same specimen throughout. The crystals of about 50 microm length and the bright spots were observed by CLSM at the bottom of the cavity induced by laser irradiation. They turned out from the observation by WET-SEM as the acicular crystals with the cross section of an irregularly hexagonal shape situated parallel and perpendicular, respectively, to the inner surface of the cavity. The thickness of the thermally deteriorated zone of the cavity was about 25 microm. The crystals unidirectionally grown up to the size of several hundreds nm were also observed by AFM, while the apatite crystallites of 50-150 nm were recognized all over in non-irradiated area. All the results suggest that after instantaneous melting at the surface of teeth by CO2 laser shot the crystals of calcium phosphate were recrystalized and grown to a large size. The compositional imaging in addition to morphological observation was useful to obtain the information of the change in materials induced by laser irradiation.

The effects of the Holmium:YAG irradiation on the pulpal tissues and surface topography on root surface dentin in human teeth in vivo were studied. The exposed root surfaces of seventeen pre-immediate denture patients were scaled and root planed with a Gracey 3 - 4 curette apical to the dentinoenamel junction until smooth and hard. The prepared root surfaces of two teeth per patient were exposed with Holmium:YAG laser energy after an application of nonfilled resin/fluoride mixture. The laser exposed areas were below the dentinoenamel junction around one-half of each root surface. The opposing sides of each of the teeth received resin/fluoride but no laser energy. A third tooth was identified as a nontreated control. The HO:YAG at 2.12 microns wavelength with a defocused beam size of 3 mm was used. The amount of laser energy delivered per 3 X 5 mm area was 0.450 (+/- .05) joules with a fluence of 2.66 - 3.30 J/cm2. The teeth were extracted after periods of 45 - 120 days. The specimens were fixed in formalin and prepared for histological examination using hematoxylin and eosin stains. Microscopic evaluation of room surfaces showed increased smoothness on the laser treated sites compared to their opposing non-lased sides. Histological examination of the pulpal tissues exhibited no abnormal changes. No clinical symptoms of pulpal pathology were produced. HO:YAG laser energy proved safe for treating room surfaces of human teeth in vivo under conditions presented in this study.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Was to evaluate the abrasive effect of toothpaste with detonation nanodiamonds synthesis of various concentrations on the enamel of human teeth. The analysis of micrographs obtained by scanning electron microscopy showed a different abrasive and polishing effect of nanodiamonds in all the observed anatomical zones on the vestibular surface of the enamel of human teeth. No negative effect of the paste containing nanodiamonds on the enamel of human teeth was noted. At all concentrations of pastes containing nanodiamonds, on the vestibular surface of the enamel of the studied teeth, depot areas of densely attached particles of nanodiamonds were formed, a tendency was observed towards the formation of depots. The enamel of human teeth was mostly influenced by the concentration of nanodiamonds (2%, 2.5%). On the surface of the enamel were formed not only a depot of single nanodiamonds, but also accumulations were noted, merging into a layer in the form of a protective film. The study showed that toothpastes with nanoalases can reduce the enamel porosity, form a protective film on its surface, and thereby increase its microhardness and increase caries resistance.