Number Of Dentinal Tubules Research Articles

A software approach for identifying the effect of dental caries on dentin-enamel junction.

Dental decay is the most prevalent oral disease worldwide since more than 2.4 billion people suffer from caries of permanent teeth. Therefore, any details about its progression into the hard-dental tissues could contribute to unravelling the mechanisms underlying this process. We have analyzed dental tissue sections with and without caries in order to detect structure differences corelating them with clinical aspects observable from the tooth surface. Our working hypothesis was based on finding a link between the process of tertiary dentin laying (as a response to coronal caries) and the subsequent obliteration of dentin tubules. We have selected N=10 extracted teeth with/without coronal caries, resin-embedded and sectioned them. A specific software was used to digitally quantify the density of unobliterated dentin tubules reaching the dentin–enamel junction (DEJ), considering as positive threshold criteria the presence of the odontoblast process inside the analyzed tubule. This study showed the differences between the healthy and carious-affected hard-dental coronal tissues. More odontoblast processes reached the DEJ in unaffected teeth. Using specific software, we have quantified their density decrease near a lesion. We have studied the dynamics of the carious study and measured the consequent structural modifications of the dentin. In conclusion, there is a significant difference between the number of dentin tubules containing odontoblast processes that reach the DEJ in healthy/altered tissues. The tooth reacts not only by production of tertiary dentin to protect the pulp chamber, but also by obliteration of dentin tubules, thus reducing the number of odontoblast processes reaching the DEJ. This pilot study could serve as the starting point in developing a dedicated software that could deliver a personalized pattern for decay progression by analyzing one single tooth and extrapolate the result to all the patient’s remaining ones.

Effect of three collagen crosslinkers on the shear bond strength of self – etch adhesive system to dentin at varying time intervals.

Abstract
 Background:
 When resin composite is bonded to dentin, the bond strength reduces with increase in depth of dentin. This is due to the increase in number of dentinal tubules, their diameter and less amount of intertubular dentin compared to “superficial dentin.21”
 Objective:
 This study proposes to improve bond strength of dentin to composite by biomodifying the dentin substrate prior to application of composite with three different crosslinking agents i;e Glutaraldehyde, Genipin and Riboflavin at varying time intervals.
 Method:
 42 extracted maxillary incisor teeth were selected. Teeth were sectioned to mesial and distal halves. (n=84). Specimens were divided into 4 groups. Group I was used as control group and Glutaraldehyde, Genipin and Riboflavin crosslinking agents were applied to other groups (II, III, IV) respectively before applying composite resin. These groups were further subdivided into A and B groups based on time of applying crosslinking agent. Shear bond strength was calculated for all specimens using universal testing machine. Results were analysed using Student t test for intra-group and inter-group comparison.
 Results:
 Greater bond strengths were recorded in all the groups compared to the control group. Application of Glutaraldehyde and Genipin as crosslinking agents reported higher shear bond strength compared to application of Riboflavin. The mean shear bond strength values further increased with increased application time of crosslinking agent. 
 Conclusion:
 Dentin surface pre-treatment with crosslinking agents at varying time intervals
 substantially improved the bond strength.
 

EVALUATION OF ALIZARIN DYE PENETRATION INTO DENTINAL TUBULES FOLLOWING FINAL RINSE BY Q-MIX AND APPLE VINEGAR: AN IN VITRO STUDY

Introduction: Successful treatment of a root canal aims for removal of microorganisms from the canal. Therefore, intraradicular removal of the smear layer is a remarkable measure for long-established endodontic success. Aim of the study: to assess Alizarin dye penetration into dentinal tubules following Q-Mix, apple vinegar, and 17% ethylenediaminetetraacetic acid (EDTA) under confocal laser scanning microscope (CLSM). Materials and method: Thirty extracted single-canaled mandibular premolars went through decoronating to 15 mm length to undergo cleaning and instrumentation. Then, they were allocated at random into three groups based on the final rinse used: Group I: 10 ml of 17% EDTA for 1 minute, Group II: 10 ml of apple vinegar for 1 minute, and Group III: 10 ml Q-MIX for 1 minute. All root canals were irrigated by 5ml Sodium hypochlorite labeled with Alizarin red. Samples were horizontally sectioned and evaluated under CLSM at distinct canal levels. Data were analyzed using (Kruskal Wallis and Friedman’s) Tests. Results: The three tested groups showed no statistically significant difference with p> 0.05. Regarding the coronal and middle thirds of EDTA, ACV, and Q-Mix groups, most of the specimens recorded score 3 (less than 50% of the whole number of dentinal tubules were penetrated with the dye) while the specimens of apical thirds recorded score 2 (traces of the dye could be seen along the internal canal surface). Conclusions: Q-Mix, Apple vinegar, and EDTA promoted the penetration through dentinal tubules in the coronal and middle sections superior to the apical section of the root canal.

Morphological Characterization of Deciduous Enamel and Dentin in Patients Affected by Osteogenesis Imperfecta

The purpose of this study was to clarify the structural and ultrastructural alterations of the enamel and dentin collagen network in the deciduous teeth of children affected by osteogenesis imperfecta (OI) using field-emission in-lens scanning electron microscopy (FEI-SEM) and transmission electron microscopy (TEM) analyses. Exfoliated primary teeth were collected from children with a diagnosis of OI and from healthy individuals (N = 24). Tooth slices containing both dentin and enamel were fixed, dehydrated and dried, gold sputtered, and observed using FEI-SEM. Additional dentin fragments were decalcified, dehydrated, embedded in resin, cut, and processed for TEM analysis. Under FEI-SEM, the enamel in OI-affected children showed an irregular prism distribution with the enamel hydroxyapatite crystals unpacked. Ultrastructural correlative analysis of the dentin in patients affected by OI showed an altered collagen pattern with a low density. In some areas, teeth in OI patients showed a reduction in the number of dentinal tubules, with odontoblastic process missing in most of the tubules. The presence of altered dentine and enamel organization in OI children was firmly established at an ultrastructural level, but additional biochemical studies are necessary in order to clarify quantitatively and qualitatively the collagenic and non-collagenic proteins in this disorder.

Evaluation of the effects of the solution used for electrochemical dissolution of nickel-titanium endodontic files on dentine structure, microhardness and cell viability.

To evaluate the effects of the [NaF 12gL-1 +NaCl 1gL-1 ] solution used in the electrochemical dissolution process of fractured endodontic files, as well as its NiTi-containing product, on dentine hardness, topography and human fibroblast viability. Sixty single-rooted human teeth were evaluated for dentine microhardness using the Vickers hardness test and the area and number of dentinal tubules by scanning electron microscopy. The samples were divided according to the dentine surface treatment: distilled water; 17% EDTA; [NaF 12gL-1 +NaCl 1gL-1 ]; and 17% EDTA+[NaF 12gL-1 +NaCl 1gL-1 ]. Thirty-six single-rooted human teeth were divided according to the irrigation protocol: Dulbecco's Modified Eagle's Medium+10% foetal bovine serum; 5.25% NaOCl; [NaF 12gL-1 +NaCl 1gL-1 ]; and [NaF 12gL-1 +NaCl 1gL-1 +NiTi]. The extracts in contact with the apical foramen were used in the MTT assay to evaluate human fibroblast viability, with dilutions of 100%, 50%, 25% and 12.5%. Statistical tests used were paired t-tests, one-way anova, Tukey's test, Kruskal-Wallis test and Dunn's post-test. The [NaF 12gL-1 +NaCl 1gL-1 ] solution did not modify dentine microhardness or the average dentinal tubule area. However, EDTA induced changes in dentine structure and microhardness (P<0.05). The [NaF 12gL-1 +NaCl 1gL-1 ] solution, and its NiTi-containing product had lower cytotoxicity than NaOCl at dilutions of 25% and 50% (P<0.01). The [NaF 12gL-1 +NaCl 1gL-1 ] solution did not alter dentine microhardness or damage the dentine structure. It also demonstrated lower cytotoxicity than NaOCl.

Retreatment of flat-oval root canals with a self-adjusting file: an SEM study.

This study evaluated the efficacy of the Self-Adjusting File (SAF) in removing the root filling remnants and smear layer left in oval shaped root canals after using R-Endo retreatment files, by using scanning electron microscopy (SEM). Forty eight maxillary premolars were prepared and the SAF was used in all of the teeth to remove debris and smear layer. Sixteen teeth were used as control and the other 32 teeth were obturated and randomly assigned to two groups according to the retreatment procedures: R-Endo retreatment files and R-Endo retreatment files+SAF. Then, all roots were split longitudinally for SEM evaluation. Using SEM pictures, the number of dentinal tubules and the surface area covered by filling remnants were evaluated. None of the techniques removed root filling remnants and smear layer completely. Additional use of SAF after the retreatment procedures may improve root canal cleanliness in the coronal and middle thirds of oval root canals.

In-vitro assessment of effect of a hydroxyapatite containing desensitizing agent on dentinal ubule occlusion

Aim and Objectives: Dentinal hypersensitivity (DH) is a common clinical condition usually associated with exposed dentinal surfaces. The present study evaluated the influence of topical application of hydroxyapatite containing desensitizing agent (Remin Pro) on dentinal tubule occlusion. Materials and Methods: A total of 22 dentin discs obtained from 11 anterior teeth were divided into two groups. Test group (Remin Pro) and control group (distilled water). The specimens treated with 17% ethylene diamine tetraacetic acid gel prior to the application of test agents followed by rinsing and application of test agents for 5 min. After rinsing, 5% Evans blue dye was applied on both the specimens. The specimens were observed under light microscope. A quantitative analysis of tubular occlusion was done by counting the number of dentinal tubules/1000 μm 2 , diameter of dentinal tubules (μm), and closed tubular area (μm 2 ). Percentage of tubular occlusion was calculated in both the groups. Results: Mean number of occluded dentinal tubules in Group A was 78.01% whereas in case of Group B it was 4.97%. With a higher percentage of tubular occlusion, the diameter and number of dentinal tubules decreased and closed tubular area of each tubule increased. Conclusion: The desensitizing agent produced significant greater dentinal tubular occlusion as compared to the control group. Clinical implications: Though in-vitro studies provide evidence for immediate dentine hypersensitivity treatment, further well-designed multicenter prospective long-term clinical trials with scanning electron microscopic evaluation are needed to find the gold standard treatment of DH.

Effect of desensitizing toothpastes on dentin

The objective of this study was to analyze the effects of toothbrushing with desensitizing toothpastes on dentin permeability and dentinal tubule occlusion. Fifty rats provided two hundred incisor teeth divided into five groups: DW, brushed with distilled water (control); FT, brushed with fluoride toothpaste; SCT, brushed with strontium chloride toothpaste; PCT, brushed with potassium citrate toothpaste; and PNT, brushed with potassium nitrate toothpaste. Cavities were prepared to expose the dentinal tubules, and the incisor teeth were brushed using the experimental agents. After each treatment, Evans blue dye solution was applied to the teeth. Dentin permeability was analyzed using scanning electron microscopy and energy-dispersive X-rays (EDX). There were significant differences (p < 0.0001, ANOVA) among the groups regarding dentin permeability, number of dentinal tubules, diameter of dentinal tubules, and opened tubular area. In the SCT, PCT and PNT groups, opened and partially occluded tubules, deposits, and a few smear layers were observed. In the DW and FT groups, most of the dentinal tubules were open, with no deposits or smear layers on the dentin. EDX revealed peaks of calcium and phosphorus in all of the groups, as well as traces of strontium in the SCT group and of potassium in the PCT and PNT groups. Desensitizing toothpaste decreased dentin permeability, although it produced only partial dentin tubule occlusion.

Comparison of Shear Bonding Strength for Two Different Etching Systems in Canine and Human Dentin

Canine dentin has increased size and number of dentinal tubules compared to human dentin. With less intertubular surface area for bonding to composite material in dog teeth, bonding shear strength may be affected negatively. This study was designed to compare the shear bonding strength of canine and human dentin. It also compared bond strength of two different acid etch systems when used with the same composite resin. The shear bond strength of composite cylinders to dentin was measured in 30 extracted canine cuspid teeth and a similar number of human molar teeth. Shear bond strength was 40% greater for human compared with canine dentin. This significantly different (P < 0.05) result validates the hypothesis that dentin bond strength is positively correlated with the area of intertubular dentin. Results also indicated that shear bond strength was greater in the self-etching bond system compared with the etch and rinse system, although this difference was not significant.

Prevalence and microscopic features of enamel pearls from permanent human molars

Enamel pearls are ectopic structures observed mainly on the roots of permanent teeth and could be related to periodontal diseases. Aim: To evaluate the prevalence of enamel pearls in extracted human molars and characterize their structures using light and scanning electron microscopy. Methods: The study comprised 2,201 extracted human permanent molars. The teeth were analyzed and classified according to morphological features. The presence, location and shape of enamel pearls were investigated. Fifteen human molars with enamel pearls were embedded in acrylic resin and observed by light microscopy. Results: Seventy-one enamel earls wereidentified on third molar root. Microscopically, most pearls were composed of prismatic irregular enamel and normal dentin. The dentinoenamel junction presented an irregular course. The number of dentinal tubules was normal and they presented curvature to continue within the root dentin of the carrier tooth. Dentinal tubules below the enamel pearls were closer to each other. Conclusions: scanning electron microscopic analysis revealed that the enamel pearls were similar to coronal enamel.Enamel pearls are ectopic structures observed mainly on the roots of permanent teeth and could be related to periodontal diseases. Aim: To evaluate the prevalence of enamel pearls in extracted human molars and characterize their structures using light and scanning electron microscopy. Methods: The study comprised 2,201 extracted human permanent molars. The teeth were analyzed and classified according to morphological features. The presence, location and shape of enamel pearls were investigated. Fifteen human molars with enamel pearls were embedded in acrylic resin and observed by light microscopy. Results: Seventy-one enamel earls wereidentified on third molar root. Microscopically, most pearls were composed of prismatic irregular enamel and normal dentin. The dentinoenamel junction presented an irregular course. The number of dentinal tubules was normal and they presented curvature to continue within the root dentin of the carrier tooth. Dentinal tubules below the enamel pearls were closer to each other. Conclusions: scanning electron microscopic analysis revealed that the enamel pearls were similar to coronal enamel.

Topographical, Diametral, and Quantitative Analysis of Dentin Tubules in the Root Canals of Human and Bovine Teeth

The aim of this study was to evaluate the number and the diameter of dentin tubules in root canals, in the cervical, middle, and apical thirds, of human and bovine teeth. Twenty-four single-rooted, human premolars were divided into four groups (n = 6): GH1, 10 to 15 years; GH2, 16 to 30 years; GH3, 31 to 45 years; and GH4, 46 to 80 years; and 24 bovine incisors were divided into four groups (n = 6): GB1, central; GB2, lateral first; GB3, lateral second; and GB4, lateral third. The crowns were removed from the specimens, which were then debrided, sectioned longitudinally in the vestibular-lingual direction, and submitted to ultrasonic cleaning. Scanning electron microscopic evaluations were made with 1,000x and 5,000x magnification. According to the root thirds, statistically significant differences were found both for the number and the diameter of dentin tubules, with the cervical third presenting the highest mean values for both specimen types. As regards the number of dentin tubules, it was observed that the bovine specimens presented a significantly higher mean value than the human specimens; this difference was not observed when the diameters of the two types were compared.

Micromorphological Analysis of Dentinal Structure after Irradiation with Nd:YAG Laser and Immersion in Acidic Beverages

The purpose of this study was to analyze dentinal surfaces that were exposed to acidic beverages, then treated with Nd:YAG laser and afterwards exposed to acidic beverages again. Dentin hypersensitivity can result from surface erosion caused by acidic beverages, which exposes and enlarges the dentinal tubules. Nd:YAG laser has been used as a treatment option. Sixty-eight dentin samples were prepared and assigned to five groups: G1, control (n = 4); G2, 3-h immersion (n = 16); G3, 3-h immersion + Nd:YAG; G4, 3-h immersion + Nd:YAG + 3-h immersion; and G5, 3-h immersion + Nd:YAG + 6-h immersion. Each group was divided into four subgroups, with different acid beverages: lemon (n = 4); passion fruit (n = 4); cola (n = 4); and wine (n = 4). Irradiation with the Nd:YAG was in contact mode, focused and perpendicular through a quartz fiber of 300 microm of diameter in scanning movements for 60 sec with a 10-sec interval and the paramenters 0.6 W, 10 Hz, 60 mJ, and 85 mJ/cm(2). Each subgroup was examined by scanning electron microscope. All the acidic beverages contributed to exposure and increased diameter of the dentinal tubules. Irradiation with Nd:YAG laser produced obliteration of and reduction in the number of dentinal tubules, thus modifying the original structure.

Age-related changes in cyclic voltammetry and potentiodynamic studies of normal human dentine.

Impedance spectroscopy is one of the non-destructive techniques used by researchers to measure electrical resistance of biological tissues and ceramics. The purpose of this study is to investigate the voltage-current (V-I) characteristics of sound human dentine from young and old teeth, using cyclic voltammetry and potentiodynamic techniques. Dentine samples were prepared from freshly extracted sound third molars. After electrical measurements, dentine samples were characterized using scanning electron microscopy (SEM). Cyclic voltammetric measurements showed that variation of current through sample as a function of applied voltage is linear for dry samples of both age groups. However, for wet samples V-I characteristic were found to be different. The resistivity of dry young dentine is greater than that of old dentine in dry environment, whereas, it was found to be opposite for wet dentine samples. Using the same voltage sweep in potentiodynamic measurements dry samples display similar traces to controls suggesting that the dry dentine acts as an insulator. The number of dentinal tubules and their diameter has been found to decrease with increasing age. We propose that these changes determine the changes in electrical characteristics of sound human dentine. In spite of increasing use of electrical techniques to understand electrical properties of teeth, it is clear from this study that local structural variations and environment have a marked influence. Therefore, this baseline data needs to be considered in any future study or clinical application.

Effects of rotary instrumentation and different etchants on removal of smear layer on human dentin

Statement of problem. Various methods of rotary preparation and conditioning of teeth affect surface topography and may affect the retention of dental restorations.Purpose. This study microscopically evaluated dentin surfaces prepared by different rotary instruments and etched using several types of acid etchants that have been deemed suitable dentin conditioners.Material and methods. Occlusal surfaces of 35 extracted human molars were ground wet with 320-grit silicon carbide paper to the depth of the central groove and then prepared with diamond (n = 5) and finishing burs (n = 30). Five specimens from each group were used for SEM evaluation of mechanical preparation effects. Dentin specimens (n = 5) prepared with finishing burs were then etched with 1 of 5 etchants (25% polyacrylic acid, 10% phosphoric acid, 10% citric acid, 20% lactic acid, or 32% phosphoric acid) for 10 seconds. Specimens were critical-point dried and freeze fractured for SEM analysis.Results. Diamond rotary instruments created more undulating surfaces than finishing burs. Fine grooves were observed running perpendicular to undulations and parallel to the direction of instrument rotation. Specimens prepared with finishing burs exhibited a smooth surface interrupted by only a slight granularity. The amorphous smear layer was partially removed after the application of 25% polyacrylic acid (pH 1.53), but all dentinal tubules contained plugs. The number of dentin tubules containing plug material and the amount of material in the tubules decreased noticeably with 10% phosphoric acid (pH 0.86), and the dentin surface had an appearance similar to the specimen etched with 10% citric acid (pH 1.70). The surfaces treated with 20% lactic acid (pH 1.40) produced a clearly etched surface with minimal demineralization. Etching of dentin with 32% phosphoric acid (pH 0.16) revealed significant changes in dentin with the evidence of increased tubule diameter.Conclusion. Differences related to the method of instrumentation were found in the surface characteristics of dentin. The degree of smear layer removal was related to the pH of the acid etchant. (J Prosthet Dent 2001;85:67-72.)

The dentin-predentin complex and its permeability: anatomical overview.

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.

Dentinogenesis imperfecta in the Brandywine isolate (DI type III): Clinical, radiologic, and scanning electron microscopic studies of the dentition

Teeth of seven patients from the Brandywine isolate who had dentinogenesis imperfecta (DI) type III were evaluated by clinical, radiologic, and scanning electron microscopic techniques. The deciduous and permanent teeth were opalescent, and there was marked attrition. Enamel pitting was present on some permanent teeth. Anterior open bites were found in all persons with complete permanent dentitions. Pulps of developing teeth were larger than normal during early development but rapidly became almost completely obliterated. There was increased constriction at the cementoenamel junctions. While radiolucencies were noted at the apices of teeth which had pulp exposures due to attrition, several patients had similar radiolucencies which could not be attributed to caries or attrition. Scanning electron microscopy showed a significant reduction in the number of dentin tubules on fractured dentin surfaces; calcospherites at the calcification front were either irregularly shaped or absent. A single tooth from a patient with DI type II was studied and had similar abnormalities on scanning electron microscopy, although tubules were easier to find and calcospherites at the calcification front were more regular than in DI type III. The findings in DI type III of enamel pitting, enlarged pulps early in tooth development, and radiolucencies at the apices of teeth without pulp exposures support the hypothesis that DI type II and DI type III are different disorders.