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Lasers in Surgery and Medicine 1997The use of excimer lasers for treatment of dental hard tissues has considerable potential because the combined characteristics of low wavelength and short pulse result...
BACKGROUND AND OBJECTIVE
The use of excimer lasers for treatment of dental hard tissues has considerable potential because the combined characteristics of low wavelength and short pulse result in limited heat diffusion and, therefore, tissue ablation without the problems of collateral damage. To date, there are relatively few published studies concerning the effects of excimer laser irradiation on dental hard tissues. Thus the present study was conducted to examine the morphological changes in tooth dentin subsequent to ArF excimer laser irradiation.
STUDY DESIGN/MATERIALS AND METHODS
The morphologic changes induced in normal, nondiseased human dentin following irradiation by an ArF excimer laser at fluences ranging from 1 to 4 J/cm2 and the number of laser pulses ranging from 50 to 1,000 were evaluated by scanning electron microscopy.
RESULTS
Two modes of ablation, photochemical at low fluences and thermal at high fluences, were observed. A fluence of 1 J/ cm2 when combined with 50 or 100 pulses produced a uniform ablation of the dentin surface without signs of tissue melting. At fluences > 1.5 J/cm2, the thermal mode of ablation was more efficient at removing intertubular dentin than peritubular dentin. Further, when compared to the lower fluences, the higher settings produced a rougher ablation crater surface. Additionally, the higher fluences produced surface melting with each pulse and sealing of exposed dentinal tubules after irradiation with 100-300 laser pulses.
CONCLUSIONS
The photochemical and thermal mechanisms of tooth dentin ablation were identified based on significant differences in tissue morphology following laser irradiation. The rates of tissue ablation and the observed morphologic changes indicate that the ArF excimer laser could be useful for caries removal and sealing of exposed dentinal tubules.
Topics: Dentin; Humans; In Vitro Techniques; Laser Therapy; Lasers; Microscopy, Electron, Scanning
PubMed: 9365958
DOI: 10.1002/(sici)1096-9101(1997)21:5<474::aid-lsm9>3.0.co;2-n -
Brazilian Oral Research 2010Dentin hypersensitivity (DH) is a painful response to stimulus applied to the open dentinal tubules of a vital tooth. It's a common oral condition, however, without an...
Dentin hypersensitivity (DH) is a painful response to stimulus applied to the open dentinal tubules of a vital tooth. It's a common oral condition, however, without an ideal treatment available yet. This work evaluated in vitro the effect of micron-sized particles from a novel bioactive glass-ceramic (Biosilicate) in occluding open dentinal tubules. A dentin disc model was employed to observe comparatively, using scanning electron microscopy (SEM), dentinal tubule occlusion by different products and deposition of hydroxyl carbonate apatite (HCA) on dentin surface by Biosilicate, after a single application: G1 - Dentifrice with potassium nitrate and fluoride; G2 - Two-step calcium phosphate precipitation treatment; G3 - Water-free gel containing Biosilicate particles (1%); G4 - Biosilicate particles mixed with distilled water in a 1:10 ratio; all of them after 1, 12 and 24 hours of immersion in artificial saliva. Fourier transform infrared spectroscopy (FTIR) was performed to detect HCA formation on dentin discs filled with Biosilicate after 2 minutes, 30 minutes and 12 hours of immersion in artificial saliva. SEM showed a layer of HCA formed on dentin surface after 24 hours by G4. G1, G2 and G3 promoted not total occlusion of open dentinal tubules after 24 hours. FTIR showed HCA precipitation on the dentin surface induced by Biosilicate after 30 minutes. The micron-sized particles from the bioactive glass-ceramic thus were able to induce HCA deposition in open dentinal tubules in vitro. This finding suggests that Biosilicate may provide a new option for treating DH.
Topics: Ceramics; Dentin; Dentin Desensitizing Agents; Dentin Sensitivity; Microscopy, Electron, Scanning; Saliva, Artificial; Spectroscopy, Fourier Transform Infrared; Surface Properties; Time Factors
PubMed: 21180956
DOI: 10.1590/s1806-83242010000400002 -
Dental Materials Journal Sep 2006To evaluate the effect of a dentin adhesive on sclerotic dentin, contraction gap width and shear bond strength were measured. Dentin cavity wall was pretreated with an...
To evaluate the effect of a dentin adhesive on sclerotic dentin, contraction gap width and shear bond strength were measured. Dentin cavity wall was pretreated with an experimental dentin bonding system with and without a dentin primer, or with a commercial dentin bonding system. In the experimental dentin bonding groups, contraction gap width of sclerotic dentin was significantly smaller than that of sound dentin when the cavity was not primed with glyceryl monomethacrylate. For each individual tooth, the correlation between contraction gap width and shear bond strength was insignificant. In conclusion, the bonding efficacy of dentin bonding systems to sclerotic dentin was superior to that of sound dentin. Further, it was determined that it was impossible to detect the interaction between the polymerization contraction stress of resin composites and the efficacy of dentin adhesives by measuring bond strength.
Topics: Adhesives; Analysis of Variance; Dental Bonding; Dental Marginal Adaptation; Dentin; Dentin-Bonding Agents; Humans; Sclerosis; Shear Strength; Statistics, Nonparametric
PubMed: 17076330
DOI: 10.4012/dmj.25.576 -
Journal of Structural Biology Aug 2013Dentin is a mineralized collagen tissue with robust mechanical performance. Understanding the mechanical behavior of dentin and its relations to the dentinal structure...
Dentin is a mineralized collagen tissue with robust mechanical performance. Understanding the mechanical behavior of dentin and its relations to the dentinal structure can provides insight into the design strategies to achieve tooth functions. This study focuses on the inelastic deformation of human dentin and its underlying mechanisms. By combining four-point bending tests with fluorescent staining and laser scanning confocal microscopy, it was found that human dentin, especially root dentin, exhibited significant inelastic deformation and developed extensive microdamage in the form of microcracks prior to fracture. Dense and wavy microcracks spread uniformly across the tensile surface of root dentin, while compressive microcracks formed cross-hatched patterns. The presence of peritubular dentin in coronal dentin dramatically decreased the extent of microcracking, reducing inelasticity. Dentinal tubules were found to be initiation sites of both tensile and compressive microcracks. A unique crack propagation process was observed in root dentin under tension: numerous ring-shaped cracks formed at each dentinal tubule ahead of a growing crack tip. The advance of the tensile microcracks occurred by the merging of those ring-shaped cracks. The current findings on the microcracking process associated with inelastic deformation helps to understand the nature of strength and toughness in dentin, as well as the mechanical significance for structural variations across the whole tooth.
Topics: Biomechanical Phenomena; Collagen; Dentin; Elasticity; Humans; Stress, Mechanical; Tensile Strength; Tooth Fractures; Tooth Root
PubMed: 23583703
DOI: 10.1016/j.jsb.2013.04.002 -
Lasers in Medical Science Nov 2013The aim of the current investigation was to assess the rate and magnitude of dentin fluid flow of dentinal surfaces irradiated with Er,Cr:YSGG laser. Twenty extracted...
The aim of the current investigation was to assess the rate and magnitude of dentin fluid flow of dentinal surfaces irradiated with Er,Cr:YSGG laser. Twenty extracted third molars were sectioned, mounted, and irradiated with Er,Cr:YSGG laser at 3.5 and 4.5 W power settings. Specimens were connected to an automated fluid flow measurement apparatus (Flodec). The rate, magnitude, and direction of dentin fluid flow were recorded at baseline and after irradiation. Nonparametric Wilcoxon signed ranks repeated measure t test revealed a statistically significant reduction in fluid flow for all the power settings. The 4.5-W power output reduced the flow significantly more than the 3.5 W. The samples showed a baseline outward flow followed by inward flow due to irradiation then followed by decreased outward flow. It was concluded that Er,Cr:YSGG laser irradiation at 3.5 and 4.5 W significantly reduced dentinal fluid flow rate. The reduction was directly proportional to power output.
Topics: Dentin; Dentin Sensitivity; Humans; Hydrodynamics; Lasers, Solid-State; Low-Level Light Therapy; Microscopy, Electron, Scanning; Pilot Projects
PubMed: 23073836
DOI: 10.1007/s10103-012-1218-9 -
Photomedicine and Laser Surgery Oct 2015The aim of this study was to investigate the effect of different energy settings of Er:YAG laser irradiation on dentin surface morphology with respect to the number of...
OBJECTIVE
The aim of this study was to investigate the effect of different energy settings of Er:YAG laser irradiation on dentin surface morphology with respect to the number of opened dentinal tubules.
BACKGROUND DATA
An ideally prepared dentin surface with opened dentinal tubules is a prerequisite for adhesive fixation. No study, however, has yet compared the numbers of opened dentinal tubules with regard to statistical differences.
METHODS
Conventional preparations using a bur with or without additional acid etching acted as control groups. Dentin specimens were prepared from human third molars and randomly divided into eight groups according to the energy settings of the laser (1, 1.5, 4, 6, 7.5, and 8 W) and two controls (bur and bur plus acid etching). After surface preparation, dentin surfaces were analyzed with a scanning electron microscope, and the number of opened dentinal tubules in a defined area was counted.
RESULTS
The control groups showed smooth surfaces with (bur plus acid etching) and without opened dentinal tubules (bur), whereas all laser-irradiated surfaces showed rough surfaces. Using the energy setting of 4 W resulted in significantly more opened dentinal tubules than the conventional preparation technique using the bur with additional acid etching. In contrast, the energy setting of 8 W showed significantly fewer opened dentinal tubules, and also exhibited signs of thermal damage.
CONCLUSIONS
The Er:YAG laser with an energy setting of 4 W generates a dentin surface with opened dentinal tubules, a prerequisite for adhesive fixation.
Topics: Adolescent; Adult; Dentin; Humans; Lasers, Solid-State; Molar; Random Allocation; Young Adult
PubMed: 26389986
DOI: 10.1089/pho.2015.3949 -
Romanian Journal of Morphology and... 2015The purpose of this study was in vitro evaluation and comparison of the adhesion of self-etch (SE) adhesive systems applied on normal and sclerotic dentin. For this... (Comparative Study)
Comparative Study
The purpose of this study was in vitro evaluation and comparison of the adhesion of self-etch (SE) adhesive systems applied on normal and sclerotic dentin. For this study, Class 5 cavities were prepared on sound teeth as well as on teeth with sclerotic dentin. They were then restored by means of the SE 2-step OptiBond XTR (Kerr) and SE 1-step Bond Force (Tokuyama Dental) adhesive systems, as well as the Estelite Sigma Quick (Tokuyama Dental) composite resin. For teeth with sclerotic dentin, the hypermineralized superficial layer was removed by means of round bur on low speed, than the adhesive systems and composite resin were applied. These teeth were prepared for microscopic study according to the protocol specific to each microscope. SEM (scanning electron microscopy) examination reveals that on normal and sclerotic dentin, OptiBond XTR and Bond Force form hybrid layers with about the same thickness, greater in normal dentin, but only OptiBond XTR pervades into the dentinal tubules, both in normal and sclerotic dentin. However, TEM (transmission electron microscopy) examination of Bond Force reveals that it penetrates into the dentinal tubules as well, but only in the case of normal dentin. The thickness of the hybrid layers resulting from the application of the SE adhesive systems to sound dentin is different from the thickness of the hybrid layers obtained when the same adhesive systems have been applied to sclerotic dentin.
Topics: Dental Cements; Dentin; Humans; Sclerosis; Spectrometry, X-Ray Emission
PubMed: 26662138
DOI: No ID Found -
Journal of Dental Research Apr 1985This paper provides an anatomical overview of the dentin-predentin complex and its permeability. An unique anatomical feature of this complex is the presence of dentinal...
This paper provides an anatomical overview of the dentin-predentin complex and its permeability. An unique anatomical feature of this complex is the presence of dentinal tubules which extend peripherally from the odontoblast-predentin junction throughout the thickness of the tissue. The permeability of dentin is a consequence of the presence of these tubules. Thus, this review concentrates on the anatomy of dentinal tubules and, in particular, on those studies which in the last decade have increased our knowledge of this anatomy. The structure, size, and number of dentinal tubules and the relationship of these features to the permeability of the tissue are discussed. This is followed by a description of the contents of dentinal tubules, with particular emphasis being paid to the literature concerning the extent of the odontoblast process.
Topics: Animals; Collagen; Dentin; Dentin Permeability; Extracellular Matrix; Exudates and Transudates; Glycosaminoglycans; Humans; Microscopy, Electron, Scanning; Nerve Fibers; Odontoblasts; Tooth Permeability
PubMed: 3857263
DOI: 10.1177/002203458506400418 -
The International Journal of... Aug 2004Odontoblasts are tall columnar cells located at the periphery of the dental pulp. They derive from ectomesenchymal cells originated by migration of neural crest cells... (Review)
Review
Odontoblasts are tall columnar cells located at the periphery of the dental pulp. They derive from ectomesenchymal cells originated by migration of neural crest cells during the early craniofacial development. Odontoblasts form the dentine, a collagen-based mineralized tissue, through secretion of its collagenous and noncollagenous organic matrix components and by control the mineralization process. A conspicuous cell process arises from the cell body of odontoblasts and penetrates into the mineralized dentine. After dentinogenesis, odontoblasts deposit new layers of dentine throughout life and might also form a type of reactionary/reparative dentine in response to dental caries and other external factors may affect teeth.
Topics: Dentin; Dentinogenesis; Humans; Microscopy, Electron; Odontoblasts
PubMed: 15147714
DOI: 10.1016/j.biocel.2004.01.006 -
Proceedings of the Finnish Dental... 1992Smear layers are created on hard tissues whenever they are cut with hand or rotary instruments. This thin (1-2 microns) layer of denatured cutting debris is very... (Review)
Review
Smear layers are created on hard tissues whenever they are cut with hand or rotary instruments. This thin (1-2 microns) layer of denatured cutting debris is very tenacious and, in fact, is often the surface to which restorative materials are luted. The solubility characteristics, chemical reactivity and the structure-function relationships of this layer have not yet been well-defined. During creation of the smear layer, cutting debris is forced variable distances into dentinal tubules. These so-called smear plugs, together with the smear layer decrease dentin permeability, dentin sensitivity and surface wetness. Bonding adhesive resins to smear layers appears to limit the theoretical bond strength unless the smear layers are loosened or partially removed. Future research in this area will include the use of surface analytical techniques such as Auger electron spectroscopy and ESCA. These techniques are required because of the thinness of the smear layer. It is clear that the nature of this critical interface between dental materials and cut hard tissues remains largely unknown. This field will provide fertile ground for future research.
Topics: Animals; Dentin; Humans; Smear Layer
PubMed: 1508877
DOI: No ID Found