Dentin Of Primary Teeth Research Articles

Microtensile bond strength of a total-etching versus self-etching adhesive to caries-affected and intact dentin in primary teeth

The objec tives of this study were to determine microtensile bond strengths of two dentin adhesives and to compare the micromorphological structure of the resin/dentin interface in caries-affected dentin with that of intact dentin. The authors randomly divided 40 proximal dentinal carious primary teeth and 40 noncarious anterior primary teeth into two groups (self-etching and total-etching). They used a caries-detecting dye as an indicator of the need to remove the outer carious dentin. The authors restored the teeth with a hybrid resin-based composite. After 24 hours' storage in 37 C water, specimens were sectioned and shaped to form a curved section with a cross-sectional area of 1 square millimeter, then tension was applied until they fractured. The authors prepared the resin/dentin interfaces for the two bonding systems and examined them in 10 occlusal carious and 10 noncarious teeth. The bond strengths for intact and caries-affected dentin within the same group were analyzed via a t test. The authors compared the remaining dentin thickness (RDT) and dentin hardness using analysis of variance and the least significant difference test at the .05 level of significance. The self-etching adhesive demonstrated no statistical difference in bond strength between intact and caries-affected dentin. However, the total-etching adhesive demonstrated different bond strengths for intact and caries-affected dentin. Moreover, the RDT of specimens with intact and caries-affected dentin was not significantly different, whereas the dentin hardness of caries-affected dentin was significantly lower than that of intact dentin. The authors found a thicker hybrid layer in intact and caries-affected dentin of specimens in the total-etching group. The adhesives exhibited significantly different bond strengths in intact dentin of primary teeth. However, they exhibited similar bond strengths in caries-affected dentin.

Influence of Zinc-Oxide Eugenol, Formocresol, and Ferric Sulfate on Bond Stength of Dentin Adhesives to Primary Teeth

This study evaluated in vitro the influence of a temporary filling {zinc oxide-eugenol (ZOE)} and two pulpotomy agents {formocresol (FC) and ferric sulfate (FS)} on shear bond strength (SBS) of two dentin adhesives to the dentin of primary molars. A total of 80 dentin surfaces were prepared and randomly allocated into 10 groups of 8 specimens each. Groups were subjected to different treatments, which included covering with a paste of ZOE mixed at different powder:liquid (P:L) ratios, placement on a gauze soaked in FC or FS, or they received no pretreatment and served as a control. XRV Herculite composite cylinders were bonded to dentin surfaces using Prime and Bond NT adhesive resin or Opti Bond Solo Plus adhesive resin. SBSs were determined using the lnstron testing machine running at a crosshead speed of 0.5 mm/min. The use of ZOE mixed at the lower P:L ratio of 10g:2g significantly decreased the values of SBS of the two adhesives. The use of two pulpotomy agents (FC and FS) significantly decreased the SBS of the two adhesives. The bond strength to dentin of primary teeth was influenced by the pulpotomy agents used and the ZOE P:L ratio but not by the adhesive system used.

Effects of One Versus Two-layer Applications of a Self-etching Adhesive to Dentin of Primary Teeth: A SEM Study

Resin composite is increasingly the material of choice for the restoration of primary teeth, and new materials with simplified procedures are increasingly being offered. Self-etching primers have been developed to simplify the bonding procedures. Some manufacturers recommend the application of these materials in two layers. However little is known about the application times. Therefore, this study evaluated the quality of the interfacial seal and the micromorphology of the hybrid layer in composite restorations bonded with one or two layer applications of a self-etching adhesive to the dentin of the primary teeth. The superfacial dentin (within 1-2 mm of dentinoenamel junction (DEJ)) on the occlusal surfaces of fourteen primary molars was exposed by a flat cut perpendicular to the long axis of the tooth. The occlusal surfaces were divided into two halves by a 1 mm deep groove in the labial-lingual orientation. The teeth were randomly divided into two groups: Group 1: Single Bond (control group) was applied according to the manufacturer's instructions on one half of the surface. On the other half of the same tooth, one layer of Prompt-L-Pop (experimental group) was applied according to the manufacturer's instructions. Group 2: the teeth received the same bonding regimes as group 1, but the experimental group had two layer application of Prompt-L-Pop. All samples were analyzed in SEM. Student's t-test was used to compare the width of the gap and hybrid layer thickness generated by experimental groups and control. There was a statistically significant difference between control (Single Bond) and the experimental groups (one or two layer application of Prompt-L-Pop) (p<0.05). Single Bond showed the best results. Two layer application of Prompt-L-Pop showed better sealing ability than one layer application of it (p<0.05). Only Single Bond presented a visible hybrid layer that had an average thickness of 3.7microm.

Shortening of primary dentin etching time and its implication on bond strength

The aim of this study was to investigate the influence of shortening the etching time on the bond strength of a conventional and a self-etching primer adhesive system used in primary tooth dentin. Flat dentin surfaces were obtained from 24 primary molars, randomly assigned to 4 experimental groups. The adhesive systems Single Bond and Clearfil SE Bond were applied in two groups according to the manufacturers' recommendations. In the other two groups, the adhesives were applied after half-time of acid etching, 7 s for Single Bond and 10 s for Clearfil SE Primer. Resin crowns were built up and after 24 h storage in water at 37 degrees C, the teeth were sectioned to produce beams with cross-sectional area of approximately 0.49 mm2. Specimens were tested in tension at 0.5 mm/min until failure. Fractured specimens were analyzed to determine the failure mode. Tensile bond strengths for Single Bond in primary dentin were higher than for Clearfil SE Bond. Shortening of acid etching time improved bond strength only for Single Bond, while no statistically significant difference was observed for Clearfil SE Bond when both etching times were compared. No detrimental effect on bond strength was observed when the time of acid etching was shortened in 50%. Shortening the time for a procedure in a small child without compromising the quality of the work is a very important finding for the practicing pediatric dentist.

Characterising the micro-mechanical behaviour of the carious dentine of primary teeth using nano-indentation

A better appreciation of the properties of carious dentine would be of clinical advantage in carious assessment and management. The aim of this study is to understand the deterioration of the mechanical properties of carious dentine as a result of bacterial demineralising process as well as change in dentine structures observed under scanning electronic microscope. Eight primary molar teeth with untreated carious dentine were axially sectioned and fine polished for nano-indentation. On each specimen, six lines of indentation, evenly distributed through the lesion, were made from the pulp to lesion cavity floor parallel to tubule direction using nano-indentation (Ultra Micro Indentation System, UMIS-2000), while another two indentation lines were made on an adjacent region of sound dentine in the same manner. All tests were conducted on hydrated specimens. Hardness and elastic modulus decreased significantly and progressively toward the cavity floor varying from 0.56 to 0.001GPa and 14.55 to 0.015GPa, respectively. The change in mechanical properties was in a specific pattern as a function of lesion depth, in which the hardness could be fitted to an exponential function, while the variation of the elastic modulus across the entire lesion was fitted to a power law relationship. More critical evaluation of the elastic modulus data indicated that two distinct exponential functions provided an excellent fit to the results. These changes in elastic modulus also matched the structural changes seen across a lesion, which were associated with a change from primarily peritubular to intertubular dissolution.

Bond strength to dentin of primary teeth irradiated with varying Er:YAG laser energies and SEM examination of the surface morphology.

This study aimed to assess in vitro the influence of Er:YAG laser energy on the shear bond strength of a total-etch adhesive to lased dentin of primary teeth, and observe under SEM the morphological appearance of laser-ablated dentin surfaces. For SBS, specimens were irradiated with the energies 60 mJ/2 Hz (G2), 80 mJ/2 Hz (G3), 100 mJ/2 Hz (G4). Control (G1) was not irradiated. Dentin surfaces were acid-etched, Single Bond adhesive (3 M) was applied, and resin cylinders were fabricated from Z250 resin (3 M). Bond strength was tested in shear (0.5 mm/min). For morphological analysis, specimens were irradiated using the same energies, either or not acid-etched, and observed by SEM. SBS means, in MPa, were: G1-17.89(+/-4.75); G2-12.34(+/-4.85); G3-10.30(+/-3.67); G4-10.41(+/-4.20). Overall, Er:YAG laser irradiation of primary teeth dentin, prior to the adhesive protocol, adversely affected bond strength. Furthermore, it was noticed that even though there was no significant difference among the Er:YAG laser-treated groups, the increase of laser energy resulted in increasingly cratered surfaces, regardless of acid-etching association.

Partial biochemical characterisation of collagen in carious dentin of human primary teeth

The process of dentin caries is a complex event involving demineralisation and matrix degradation. The objective of this study was to biochemically characterise collagen, the major dentin matrix component, by amino acid and cross-link analyses in two distinct carious dentin regions of human primary teeth. Twenty-seven carious primary teeth were obtained from 3 to 11-year-old patients and three layers of dentin, i.e. outer, inner carious dentin and normal dentin, were identified by a 1% acid red solution and dissected from each tooth. The samples were pulverised, the respective layers obtained from three to five teeth were pooled and six samples per layer were analysed. Aliquots of the dried dentin powder were hydrolysed with 6 N HCl at 110 °C for 24 h and subjected to amino acid analyses. Other aliquots were demineralised, reduced with standardised NaB 3 H 4 , hydrolysed and subjected to quantitative collagen cross-link analyses. The results demonstrated that in the outer carious layer the collagen-associated amino acids were significantly lower and the reducible cross-links were markedly diminished when compared to the other two groups. There was no significant difference in these parameters between the inner carious and the normal layers. The data indicate that while the collagen in the outer carious dentin is significantly altered and degraded, the one in the inner carious dentin is relatively unaffected in primary teeth.

Surface Analysis of Dentinal Caries in Primary Teeth using a pH-imaging Microscope

The aim of this in vitro study was to evaluate the pH value of intact and carious dentin in primary teeth using a pH-imaging microscope (SCHEM-100, HORIBA Ltd., Kyoto, Japan). Bucco-lingual cut sections of extracted human primary teeth, which had either mild or severe dentinal caries lesions, were placed on the pH-imaging sensor of the microscope. The pH values were compared statistically by Levene's test for equality of variances and Tukey HSD multiple comparison test (p < 0.05). For both mild and severe lesions in primary dentin, the lowest pH values in the carious lesions were lower than those of intact dentin (6.6, range 6.3-6.9). There were statistical differences between the lowest pH value within the mild lesions (6.2, range 5.8-6.4) and that of the severe lesions (6.0, range 5.9-6.2) (p < 0.05). It was concluded that SCHEM-100 was able to distinguish the pH-value distribution of intact and carious dentin in primary teeth.

Morphological characterization of the resin-dentin interface in primary teeth.

The effects of self-etching adhesives on primary teeth were evaluated. Reports in the literature suggest differences between the first and second dentition regarding the composition and the morphology and, therefore, a possible difference in the performance of dental adhesives. The purpose of this study was to evaluate the effects of self-etching adhesives on primary dentin. Eight dentin disks were obtained from the occlusal surface of primary molars. The disks were divided between four dental adhesives [Prompt L-PoP (LP), Clearfil SE BOND (SE), Etch&Prime 3.0 (EP) and Prime&Bond NT (PB) + H(3)PO(4) (Control) and "restored" with a composite (Pertac II)]. After sectioning, fixation and HMDS drying, specimens were polished and Field Emission SEM examinations were carried out. Clearly visible hybrid layer formation was found for PB, LP and EP. An undoubtedly detectable interdiffusion zone was not evident after the use of SE. A clearly visible adhesive layer was recognizable for PB, EP and SE, but not continuously detectable for LP. Debonded regions were observed for all systems evaluated, but distinct differences in the failure mode were detected. The evaluated dental adhesives did not generate completely sealed interfaces between the composite resin and the dentin of primary teeth in vitro.

Preliminary in vitro Assessment of Erosive Potential Using the Ultra-Micro-Indentation System

The aim of this study was to measure the change in hardness and modulus of elasticity of enamel and dentine in primary teeth using the ultra-micro-indentation system (UMIS) after exposure to potentially erosive beverages and to relate the changes to the chemical composition of the test beverages. Primary molar teeth were sectioned and polished. Indentations were made in enamel and dentine prior to and then after exposure to one of four beverages: distilled water (control), orange juice, Orange Cordial, Fanta^® and a ‘toothfriendly’ Tropical Orange Cordial (Ribena^®). Each beverage was then analysed. Fanta and Orange Cordial were the only test beverages to show a statistically significant reduction in the enamel hardness in comparison to the control and only Fanta showed a significant reduction in dentine hardness. None of the test beverages significantly reduced the modulus of elasticity of either enamel or dentine. Statistically the pH, phosphate and fluoride concentrations of the beverages were correlated with softening of enamel. Calcium concentration and titratable acidity were correlated with softening of dentine. The UMIS offers another method of measuring the basic mechanical properties of enamel and dentine. This is useful in predicting the erosive potential of substrates. It is likely that the pH, titratable acidity, fluoride, phosphate and calcium content of beverages are all important in determining the potential erosiveness of beverages.

Micro-mechanical characterisation of the properties of primary tooth dentine

Objective. Understanding the mechanical properties of dentine is of importance as adhesive restorative materials mainly achieve their bonding to the tooth structure through dentine. The current study measures the hardness and modulus of elasticity of primary molar dentine using an Ultra-Micro-Indentation System (UMIS), which allows the dentine to remain hydrated and thus is assumed to be closer to the in vivo conditions. Methods. Eight sound primary molar teeth were axially sectioned, embedded in resin and fine polished. Two linear arrays of indentations were done on coronal dentine, from the pulp wall to dentino–enamel junction (DEJ) parallel to the tubule direction under a force load of 25 mN. Results. The mean hardness and elastic modulus of the dentine nearest the pulp wall was 0.52±0.24 and 11.59±3.95 GPa, respectively, which was significantly lower than those of dentine in the middle area, which was 0.85±0.19 and 17.06±3.09 GPa, respectively, and the dentine nearest DEJ, which was 0.91±0.15 and 16.33±3.83 GPa, respectively. There is a statistically significant linear correlation between the hardness and modulus of elasticity. Conclusion. The hardness and modulus of elasticity of dentine decreases with decreasing distance from the pulp. This is of importance to clinicians because an extension of cavity preparation towards the pulp may lead to less mechanical support for a restoration.

GAMBARAN PENETRASI SEMEN IONOMER KACA KE DALAM DENTIN GIGI SULUNG DENGAN DAN TANPA KONDISIONER (Evaluasi Scanning Electron Microscopy)

The objective of this research was to know the difference between the penetration of glass ionomer cement (Chemflex, Dentsply) in dentin of primary teeth with and without conditoner (10% polyacrylic acid). THe primary molar tooth which were observed by Scanning Electron Microscopy (SEM) 100x magnitude ws measured for the length of glass ionomer cement penetration in dentin of primary tooth with and without conditioner. The t test showed that there was no significant difference between the length of glass ionomer cement penetration in dentin of primery teeth with and without conditioner.

PENGARUH PERBEDAAN DURASI APLIKASI KONDISIONER TERHADAP GAMBARAN PENETRASI SEMEN IONOMER KACA PADA DENTIN SULUNG (Evaluasi Scanning Electron Microscopy)

The purpose of this study was to determine whether different durations of conditioner application influenced glass ionomer cement penetration in dentin primary teeth. The conditioner being used was 10% polyacrylic acid. Samples in this study were 40 non-carious primary mandibular incisors. Samples were divided into 4 groups (10 samples each): group A, withoud conditioner, group B, with 10 seconds of conditioner application, group C, with 20 seconds of conditioner application, and group D with 30 seconds of conditioner application. Penetration of glass ionomer cement was observed using scanning electron microscopy (SEM) with 200x magnification. One-way ANOVA and Tukey HSD test showed significant difference between groups. Longer conditioner application resulted in longer glass ionomer penetration in dentin of primary teeth.

GAMBARAN PENERASI BAHAN TUMPAT KOMPOMER KE DALAM DENTIN GGI SULUNG DAN GIGI TETAP SETELAH PEMAKAIAN NON RINSE CONDITIONER (Evaluasi Scanning Electron Microscopy)

The objective of this research was to know the difference of compomer (Dyract, Dentsply) penetration in dentin of primary and permanent teeth after applied by Non-Rinse Conditioner (NRS) . The samples were observed by Scanning Electron Microscopy = SEM (1200x mag.) and the length of Compomer penetration in dentin tubules after applied by Non-Rise Conditioner were measured. T test showed that Compomer penetration in primary teeth was shorter compared to permanent teeth (t=3.474, p=0.001).

Significance of histopathologic examination in the diagnosis of dentin defects associated with type IV osteogenesis imperfecta: Two case reports

Two cases of type IV osteogenesis imperfecta, which is divided into subtypes A and B on the basis of the absence or the presence of dental alterations, respectively, are examined with respect to their dental features clinically, radiographically, and histopathologically. There were no characteristic dental abnormalities noted on the clinical and radiographic examination. However, the histopathologic examination with both light and electron microscopy disclosed characteristic dentin defects such as unevenly calcified matrixes, irregular tubular patterns, obliterated dentinal tubules, and cellular inclusions in the circumpulpal dentin of primary teeth. As a result, the patients were diagnosed as having osteogenesis imperfecta type IVB, although the clinical dental alterations were scarcely apparent. These findings indicate the importance of histopathologic examination with light and transmission electron microscopy for accurate diagnosis of osteogenesis imperfecta.

A microradiographic and electron microscopic study of tertiary dentin in human deciduous teeth

This study deals with the structure of the inorganic phase of tertiary dentin, and is limited to dentin formation caused by mild or moderate stimuli, e.g., attrition or initial or shallow carious lesions. Ground sections were prepared from 20 human deciduous teeth extracted mainly because of orthodontic treatment, and contact microradiographs were produced. Based on visual inspection of the ground sections in reflected and transmitted light and microradiographic findings, small areas were dissected out and processed for electron microscopy. In the tertiary dentin formed in the pulp horns the number of tubules was reduced, while in that on the side walls of the pulp there was often no marked reduction in the number of tubules. Several tubules could be followed from the physiological (primary and secondary) dentin into the tertiary dentin, and a change in the direction of the tubules was often noted. Interglobular dentin was frequently observed, and in some teeth incremental lines with alternating high and low mineral content were seen, indicating that tertiary dentin, like other mineralized tissues, is subject to biological rhythms during formation. When studied in the electron microscope, tubules with varying size and distribution as well as occluded tubules with a high mineral content were seen. The tubules often had an irregular circumference with projections of mineralized tissue protruding into the lumen. Highly mineralized peritubular dentin was rarely observed. The present results show that orthodentin is formed when dentin in primary human teeth is exposed to mild or moderate stimuli.

Resin bonding efficacy of Gluma 2000 to dentine of primary teeth: an in vitro study

The aim of this study was to investigate (i) the effect of Gluma 2000 conditioning solution on the dentine of primary teeth, (ii) the penetration of Gluma 2000 adhesive resin into the etched dentine, (iii) the shear bond strength of a composite resin restorative material (Pekafill) bonded with Gluma 2000 to dentine, and (iv) the depth of penetration of adhesive resin into the etched dentine as a function of the conditioning time. Dentine surfaces conditioned for 15, 30, 60 and 120 seconds were examined by scanning electron microscopy. The smear layer was totally removed and, with the longer conditioning times, a fine crystalline precipitation, presumably calcium oxalate, was formed. After Gluma 2000 bonding of composite resin and dissolution of the teeth the resin interface showed excellent penetration into the etched dentine. Shear bond strengths of composite resin bonded with the adhesive resin were similar following conditioning for 15, 30, 60 and 120 seconds. Microphotographs of debonded specimens indicated that the mode of failure was cohesive within the resin. The depth of penetration of resin into etched dentine was determined by scanning electron microscopy, and a linear relationship was found between the thickness of the resin-impregnated layer and conditioning time. It was therefore concluded that depth of resin penetration and shear bond strength are not correlated. The study shows that the Gluma 2000 bonding system produces reliable adhesion of composite resin to dentine of primary teeth.

Altered collagen expression in human dentin: increased reactivity of type III and presence of type VI in dentinogenesis imperfecta, as revealed by immunoelectron microscopy.

We used transmission immunoelectron microscopy and polyclonal antibodies to study the reactivities of Types III and VI collagen in dentin of normal human permanent and primary teeth and in primary teeth from five patients with dentinogenesis imperfecta (DI) associated with osteogenesis imperfecta and occurring as a single trait. In the normal permanent tooth, reactivity of Type III collagen was occasional and, where present, peritubular. Staining of normal primary teeth was less occasional but still rare, whereas the abnormal dentin stained more uniformly. Atypical, non-striated fibrillar structures that also showed Type III collagen reactivity were observed in dentin of two of the three patients with DI as a single trait. Later, these two patients proved to be first cousins. Unlike antibodies to the N-terminal pro-peptide of Type I pro-collagen, antibodies to the C-terminal telopeptide of Type I collagen, used for comparison stained the affected dentin homogeneously. Reactivity of Type VI collagen, not detected in normal teeth, was seen in the dentin of all abnormal teeth, in association with non-fibrillar delicate material. This study also shows that although readily detectable in dentin affected by DI, Type III collagen is a minor constituent of normal human dentin matrix.

Age estimation by aspartic acid racemization in dentin of deciduous teeth

In forensic dental medicine, one of the most important endeavors is the estimation of age. We have studied the method of age assessment using the d/l ratio of aspartic acid from the dentin. The age of deciduous teeth has been estimated by measuring the racemization reaction of this amino acid. The results of the present study indicated that the measured d/l ratio for the dentin of deciduous teeth was highly correlated with the real age ( r=0.824–0.981 (σ= ±0.5 to ±1.3). These results indicate that age can be accurately estimated from the dentin of deciduous teeth, as it can when permanent teeth are used, and that the d/l ratio is more highly correlated with age than is the eruption time of permanent teeth.

乳歯鉛濃度に関する衛生学的研究 特に環境汚染との関係について

It has been noted by some investigators that lead is present in enamel and dentin of deciduous teeth, but there are no data on lead levels in deciduous teeth in Japanese.It was reported that most air pollution in the past was caused by exhaust gas from motor vehicles and lead levels in air were very high in large cities. As a result, tetraethyl lead has been restricted as a gasoline additive since 1975 in Japan. We present an investigation of lead levels in decidous teeth, which are considered greatly influenced by lead. We have tried to find out how lead levels in enamel and dentin of deciduous teeth in Tokyo change among two groups of children of different birth generations. Lead levels were determined by Zeeman effect flameless atomic absorption spectrometry.The results were as follows:1) Since the restriction of tetraethyl lead as a gasoline additive was put into practice, lead levels in enamel of deciduous teeth in Tokyo have been reduced. The geometric mean of lead levels in enamel of deciduous teeth from the group born in 1976-1980 (1.03μg/g) was significantly lower than in the other group born in 1962-1965 (3.08μg/g). There was a reduction of 79.4% in deciduous incisors, 61.9% in canines, and 59.0% in molars.2) Lead levels in dentin of deciduous teeth in Tokyo have also been reduced. The geometric mean of lead levels in dentin of deciduous teeth from the group born in 1976-1980 (1.27μg/g) was significantly lower than in the other group born in 1962-1965 (3.37μg/g). There was a reduction of 71.1% in deciduous incisors, 46.1% in canines, and 58.3% in molars.3) Significant correlation was observed between the lead in enamel and dentin of decidious teeth.4) This indicates that lead absorption in a body is marking a decline after starting the restriction.