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PubMed1993

Postmortem estimation of age at death based on aspartic acid racemization in dentin: its applicability for root dentin.

The extent of aspartic acid racemization in total dentin and in dentin protein fractions from the roots of third molars was determined. In several cases coronal dentin was also investigated. The results of other authors, according to which the racemization of aspartic acid in root dentin apparently proceeds differently than in coronal dentin, could be confirmed. Consequently, the data published so far on age determination based on the extent of aspartic acid racemization in coronal dentin and the "entire dentin of longitudinal sections" cannot be applied to root dentin. In total root dentin and the acid soluble protein of root dentin, a close relationship was observed between the extent of aspartic acid racemization and age. Accordingly, estimation of age at death based on aspartic acid racemization in dentin is also possible for root dentin, apparently with good results. This is important particularly in those cases where a large portion of the coronal dentin is absent, for instance following dental treatment. In the investigation of root dentin, regression equations specific for root dentin must be employed in the estimation of age at death. Corresponding equations for third molars were calculated.

Adult↗
PubMed2005

Dentin sialoprotein and dentin phosphoprotein overexpression during amelogenesis.

The gene for dentin sialophosphoprotein produces a single protein that is post-translationally modified to generate two distinct extracellular proteins: dentin sialoprotein and dentin phosphoprotein. In teeth, dentin sialophosphoprotein is expressed primarily by odontoblast cells, but is also transiently expressed by presecretory ameloblasts. Because of this expression profile it appears that dentin sialophosphoprotein contributes to the early events of amelogenesis, and in particular to those events that result in the formation of the dentino-enamel junction and the adjacent "aprismatic" enamel. Using a transgenic animal approach we have extended dentin sialoprotein or dentin phosphoprotein expression throughout the developmental stages of amelogenesis. Overexpression of dentin sialoprotein results in an increased rate of enamel mineralization, however, the enamel morphology is not significantly altered. In wild-type animals, the inclusion of dentin sialoprotein in the forming aprismatic enamel may account for its increased hardness properties, when compared with bulk enamel. In contrast, the overexpression of dentin phosphoprotein creates "pitted" and "chalky" enamel of non-uniform thickness that is more prone to wear. Disruptions to the prismatic enamel structure are also a characteristic of the dentin phosphoprotein overexpressing animals. These data support the previous suggestion that dentin sialoprotein and dentin phosphoprotein have distinct functions related to tooth formation, and that the dentino-enamel junction should be viewed as a unique transition zone between enamel and the underlying dentin. These results support the notion that the dentin proteins expressed by presecretory ameloblasts contribute to the unique properties of the dentino-enamel junction.

Amelogenesis↗
PubMed2001

Six-month clinical evaluation of two dentin adhesives applied on dry vs moist dentin.

PURPOSE: Acid-etched dentin has been described to easily collapse when it is dried with air after being rinsed with water under laboratorial "ideal" conditions. Manufacturers of modern dentin adhesives recommend leaving dentin moist, regardless of the solvent used in their proprietary dentin adhesives. Nevertheless, many clinicians still dry the cavity preparation after rinsing off the etching gel to check for the enamel frosted aspect. The null hypothesis to be tested in this clinical study was that drying dentin with air upon rinsing off the acid would not result in lower short-term retention rates than when the cavity was left visibly moist. MATERIALS AND METHODS: Upon Internal Review Board approval, thirty-five patients were enrolled in this study. A total of 128 restorations divided into four groups were inserted and evaluated at baseline: (A) Prime & Bond NT, an acetone-based adhesive, applied on moist dentin; (B) Prime & Bond NT applied on dentin dried with air for 3 to 4 s; (C) Single Bond, an ethanol- and water-based adhesive, applied on moist dentin; (D) Single Bond applied on dentin dried with air for 3 to 4 s. A microfilled composite resin was used for all restorations. RESULTS: At 6 months after initial placement, 119 restorations (a 93% recall rate) were re-evaluated. Retention rates at 6 months were 97% (one failure) for Single Bond/moist dentin and 100% for the remaining three groups; however, they were not significantly different (retention rate vs dentin adhesive; retention rate vs moisture). CONCLUSION: Dentin substrate in noncarious lesions may be less sensitive to variations in dentin moisture than the "ideal" dentin substrate used under laboratory conditions.

Acetone↗
PubMed2000

Comparison of the number and diameter of dentinal tubules in human and bovine dentine by scanning electron microscopic investigation.

Detailed information on dentine structure is essential for interpreting data from investigations on dentine-adhesive materials. The purpose here was to compare the number and diameter of dentinal tubules at similarly prepared surfaces of bovine permanent central incisors and human deciduous and third molars. In bovine teeth, crowns and roots were used; in human samples only the crowns were investigated. Tubule density in the middle layer was higher in bovine root (BR) dentine (number of tubules per mm(2)+/-SD: 23, 760+/-2453) than in human deciduous (HD) (18,243+/-3845), human permanent (HP) (18,781+/-5855), and bovine coronal (BC) (17, 310+/-2140) dentine. The corresponding values for the deep layer were 23,738+/-4457 (BR), 24,162+/-5338 (HD), 21,343+/-7290 (HP), and 20,980+/-4198 (BC). No significant differences were found for the number of dentinal tubules in bovine coronal dentine compared to the dentine of human deciduous and permanent molars. The mean diameter of bovine dentinal tubules was slightly, but not significantly, higher than in human dentine (middle layer/deep layer+/-SD): BC, 2. 85 microm+/-0.18/3.50 microm+/-0.33; BR, 3.10 microm+/-0.33/3.23 microm+/-0.30; HD, 2.55 microm+/-0.16/2.82 microm+/-0.28; HP, 2.65 microm+/-0.19/2.90 microm+/-0.22. These findings demonstrate that corresponding coronal dentine layers of human deciduous and permanent molars, and of bovine central incisors, are not significantly different in their number of tubules per mm(2) and their tubule diameter, whereas tubule density in bovine root dentine is significantly higher. These results suggest that provided standardized preparations are used, bovine incisor crown dentine is a suitable substitute for human molar dentine in adhesion studies.

Adolescent↗
PubMedDate not supplied

Effect of dentine depth on the fracture toughness of dentine-composite adhesive interfaces.

OBJECTIVES: The fracture toughness test was recently introduced as a clinically relevant method for assessing the fracture resistance of the dentine-composite interface. The objective of this study was to evaluate the effect of dentine depth on the interfacial fracture toughness test of several dentine-composite interfaces using some new proprietary dentine bonding agents. METHODS: Miniature short rod fracture toughness specimens containing a chevron-shaped dentine-composite-bonded interface were prepared for each group (n = 12). Six different dentine bonding agents and two dentine depths were the variables assessed at the dentine-composite interfaces. After 24 h at 37 degrees C in water, the specimens were tested by loading at 0.5 mm/min in the Instron Universal Testing Machine. The interfacial KIC results were analysed by ANOVA, unpaired Student's t-tests and Fisher's LSD test (P < 0.05). RESULTS: The interfacial KIC results in MN.m-3/2 (S.D.) on superficial and deep dentine, respectively, were: All-Bond 2, 0.80 (0.21), 0.44 (0.13); Bond-lt, 0.75 (0.20), 0.38 (0.19); Prime and Bond, 0.56 (0.11), 0.28 (0.10); Scotchbond Multi-Purpose, 0.45 (0.23), 0.26 (0.15); One-Step and OptiBond, insufficient results due to premature specimen failures. CONCLUSIONS: The results from this study should contribute to the development of the fracture toughness test as a method for assessing the integrity of the dentine-composite interface. The interfacial fracture toughness test determined significant differences among the different dentine bonding agents and between the superficial and deep dentine substrates. The dentine bonding agents showed significantly reduced interfacial fracture toughness results when bonding to deep versus superficial dentine.

Adhesives↗
PubMed1999

Bovine dentin as a substitute for human dentin in shear bond strength measurements.

PURPOSE: To evaluate the suitability of bovine coronal and root dentin as substitutes for human primary and permanent dentin in shear bond strength tests for dentin adhesives. MATERIALS AND METHODS: 30 bovine permanent central incisors, 30 human primary and 30 human third molars were cut mesiodistally. The pulpal and buccal dentin surfaces of the buccal cuts were milled with a bur to a thickness of 1.0 mm. A dentin adhesive and a hybrid composite were applied exactly according to the instructions given by the manufacturer on each buccal and pulpal surface, except in primary teeth where only the buccal surface was used. Shear bond strength was determined after 24 hours of storage in an aqueous solution. The results were statistically analyzed using the Wilcoxon- or the Mann-Whitney-U-test. RESULTS: There were no differences in shear bond strengths between human permanent dentin and bovine coronal dentin (13.3 +/- 6.1 vs. 15.2 +/- 7.6), and between each pulpal and buccal aspect. Significant differences were found between bovine root dentin and human primary dentin (17.4 +/- 8.3 vs. 7.7 +/- 5.0, P < 0.001). Significant differences were also found between bovine root dentin and human permanent dentin (17.4 +/- 8.3 vs. 13.3 +/- 6.1, P < 0.05), and bovine root and coronal dentin (17.4 +/- 8.3 vs. 15.2 +/- 7.6, P < 0.05). Furthermore, significant differences were recorded between human primary and human permanent dentin (7.7 +/- 5.0 vs. 13.3 +/- 6.1, P < 0.001) and bovine coronal dentin (7.7 +/- 5.0 vs. 15.2 +/- 7.6, P < 0.001).

Animals↗
PubMed2003

Influence of dentinal polyelectrolytes on wet demineralized dentin, a bonding substrate.

The objective of this study was to show the influence of dissolved dentinal polyelectrolytes on the characteristics of dentin (bonding substrate) demineralized by citric acid in the absence or presence of ferric chloride. The demineralizing agent was an aqueous mixture of 0, 1, 3, or 10% ferric chloride in 10% citric acid (10-0, 10-1, 10-3, 10-10, respectively). The hypothesis was that the concentration of dissolved dentinal noncollagenous substances, mainly polyelectrolytes soluble in water, must be decreased by their aggregation with ferric ions, which changes the characteristics of demineralized dentin, the rates of demineralization, and dehydration. Cervical bovine dentin was prepared in 3 x 2 x 2-mm blocks, each weighing 20.0 +/- 0.5 mg. The rate of demineralization was investigated by measuring the weight loss resulting from demineralization by immersion in 10 mL of conditioner at 2-h intervals. The dehydration rate of wet demineralized dentin was determined using two methods: (1) weight loss in a desiccator under 263 Pa pressure and (2) differential scanning calorimetry (DSC). Twenty, 12, 8, and 4 h were required to complete demineralization of the blocks with the 10-0, 10-1, 10-3, and 10-10 solutions, respectively. The 10-10 wet demineralized dentin showed the highest rate of dehydration, followed in descending order by the 10-3, 10-1, and 10-0 specimens. Ferric chloride in dentin conditioners provided both a higher rate of dentin demineralization and a higher dehydration rate of wet demineralized dentin. These results suggest that in the presence of ferric chloride, a decreasing amount of dissolved polyelectrolytes aggregated with ferric ions in the substrates may increase the permeability of dentin to water and citric acid. Improvement of monomer permeability is essential to the preparation of good hybridized dentin, providing a more stable and reliable bonding and also protecting the dentin and pulp from infection. A further study of bonding substrates is required in order to understand the role of hybridized dentin in improved dental treatment.

Animals↗
PubMed1998

The influence of dentine permeability on cytotoxicity of four dentine bonding systems, in vitro.

Dentine adhesives are often placed directly on dentine from which the smear layer has been removed, the thickness of the dentine is minimal and the potential for diffusion of adhesive components into the pulp is greatest. The permeability of the dentine is one factor that should be critical to whether sufficient diffusion of adhesive components occurs to cause damage to pulpal cells. Dentine discs were prepared and divided into those with low-, medium-, and high-permeability. They were then treated with four different dentine adhesives, after which the pulpal side of the dentine was placed in contact with 1 mL of cell-culture medium. The medium was collected at 24 h intervals for 168 h, and was then placed on monolayers of human pulpal fibroblasts for 24 h. The response of the cells was assessed by succinic dehydrogenase activity (MTT method). The results showed that four dentine adhesive systems released sufficient components to cause suppression of cellular metabolism through dentine. High-permeability dentine generally allowed more diffusion of these components, but the effect of dentine permeability depended on the material. On the other hand, the time interval between the application of the bonding agent and collection of the eluant was consistently important for all materials. Materials were most cytotoxic at early intervals, and were generally less cytotoxic at later intervals, although there were exceptions and there was persistent (> 15%) suppression of cellular metabolism even at late (168 h) intervals. The results suggest that application of these materials to dentine, and particularly dentine with high permeability, poses a potential risk to the health of pulpal tissues.

Analysis of Variance↗
PubMed2003

Porcine enamel matrix derivative enhances the formation of reparative dentine and dentine bridges during wound healing of amputated rat molars.

We examined the biological effects of porcine enamel matrix derivative (EMD; Emdogain) on the formation of reparative dentine and dentine bridges in rat molars after pulp amputation. The pulp chambers of upper molars of Wistar rats were perforated and the amputated pulp surfaces were directly capped with either EMD or its carrier propylene glycol alginate (PGA) as control. The cavities were then restored with glass-ionomer cement. On post-amputation days 4-30, the dissected maxillae were examined by light and electron microscopy. In PGA-capped pulp, reparative dentine had been formed over the dentine walls under the prepared cavity on day 7 post-amputation and its thickness extended until day 30. On day 30, as well as reparative dentine formation, diffuse calcification had occurred beneath the amputated wound surfaces. Dentine bridge formation under the amputated coronal pulp surface was observed in 18.2% of amputated pulp on day 30. In EMD-capped pulp, reparative dentine had already been formed by odontoblast-like cells over the dentine walls, already on day 4 post-amputation, and its thickness extended until day 30. The Ca and P weight % and Ca/P ratio of reparative dentine matrix were similar to those of pre-existing dentine matrix, and these values were not different between PGA and EMD-capped pulp. Dentine bridge formation was observed in 27.3% of EMD-capped pulp on day 30. Our results suggest that EMD enhances the formation of both reparative dentine and dentine bridges during wound healing of amputated rat molar pulp.

Amputation, Surgical↗
PubMed2006

Contraction gap versus shear bond strength of dentin adhesive in sound and sclerotic dentins.

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.

Adhesives↗
PubMedDate not supplied

Nanoleakage of dentin adhesive systems bonded to Carisolv-treated dentin.

The hybrid layer created in caries-affected dentin has not been fully elucidated and may influence bond durability. This study investigated the nanoleakage patterns of caries-affected dentin after excavation with Carisolv or conventional instruments treated with one of three adhesive systems. Flat occlusal dentin surfaces, including carious lesions, were prepared from extracted human molars and finished with wet 600-grit silicon carbide paper. Carious dentin was removed with Carisolv or round steel burs in conjunction with Caries Detector. PermaQuik, Single Bond or One-Up Bond F was bonded to the excavated dentin surfaces and adjacent flat occlusal surfaces and it was covered with Silux Plus resin-based composite. After 24-hour storage in 37 degrees C water, the bonded interfaces were polished to remove flash, and the surrounding tooth surfaces were coated with nail varnish. Specimens were immersed in 50% (w/v) silver nitrate solution for 24 hours, exposed to photo developing solution for eight hours, then sectioned longitudinally through the bonded, excavated dentin or "normal" dentin surfaces. The sectioned surfaces were polished, carbon coated and observed in a Field Emission-SEM using back scattered electrons. Silver deposition occurred along the base of the hybrid layer for all specimens. However, Single Bond showed a greater density of silver deposition in the caries-affected dentin compared with normal dentin. PermaQuik had a thicker hybrid layer in caries-affected dentin than normal dentin. One-Up Bond F exhibited a thin hybrid layer in normal dentin, but the hybrid layer was often difficult to detect in caries-affected dentin.

Acid Etching, Dental↗
PubMed1991

[Effects of CO2 laser irradiation on microstructure of dentin, dentin adhesion of resin composites and dental pulp].

This study was designed to investigate the effects of CO2 laser irradiation on the dentin microstructure, dentin adhesion of resin composites and dental pulp. An artificial caries lesion was produced on the bovine dentin, immersing in 0.4 mol/l acetic acid. Three kinds of dentin (sound dentin, outer or inner caries dentin) surfaces were pretreated by the laser irradiation, acid etching or no-treatment. The tensile adhesion-test of these pretreated dentin surfaces was performed. The changes in these dentin surfaces by the various treatments including the laser irradiation and the resin-dentin interfaces were examined by the SEM. Furthermore, histopathological study using monkey teeth was conducted to examine the effect of the laser irradiation on the dental pulp. Histopathological changes in the pulp were found at 3 and 90 days after the operation. The findings were as follows: 1. The outer highly and inner partially decalcified layers produced in the bovine dentin were each approximately 200 microns in thickness. 2. The bond strength of the resin composites to the laser pretreated sound dentin was approximately 40 kgf/cm2. Those of the laser pretreated outer and inner decalcified dentins were about 60 kgf/cm2. 3. At the initial stage, the laser irradiation (output power 3W : irradiation period 0.5 second) exhibited a slight pulpal response, producing irritation dentin formation in the latter stage without any severe histopathological change.

Adhesiveness↗
PubMed1997

Bond strength of one-bottle dentin bonding agents on human dentin.

PURPOSE: To evaluate the shear bond strength of one-bottle dentin bonding agents (DBA's) (Prime & Bond 2.1, ART Experimental, Syntac Single Component) on pressurized human dentin. MATERIALS AND METHODS: Freshly prepared dentin specimens of human teeth were perfused with horse serum which was diluted 1:5 in physiologic saline. Three different types of surface treatment were evaluated on the freshly prepared dentin. Group 1: One of the three one-bottle DBA's was applied onto freshly prepared dentin together with a cylinder of composite luting resin and cured. Group 2: A provisional cement (Freegenol, without eugenol, or Temp Bond, containing eugenol) was applied first on the dentin surface for 24 h. Only then was one of the three the one-bottle DBA's added onto the dentin together with a cylinder of composite luting resin after cleaning the dentin surface with pumice. Group 3: One of the three one-bottle DBA's was applied first on the dentin surface and light-cured. Then a provisional cement (Freegenol, without eugenol, or Temp Bond, containing eugenol) was added for 24 h. After cleaning with pumice, the respective one-bottle DBA was applied for a second time onto the dentin together with a cylinder of composite luting resin and light-cured. As control for Group 1 (freshly prepared dentin), the two- or three-step DBA's ART Bond and Syntac were used in a similar way. As control for Group 2 (single application of the DBA's after contamination of the dentin with a provisional cement) and Group 3 (dual application of the DBA's with intermediate contamination of the dentin with a provisional cement) the two-step DBA ART Bond was used. After 1500 thermal cycles with constant imitation of intrapulpal pressure, shear bond strengths were measured. Resulting shear bond strength values were displayed by means of a box plot and they were analyzed statistically by Student's t-Test or one-way ANOVA. RESULTS: Lowest and highest mean shear bond strength values were 0.26 +/- 0.47 MPa (single use of ART Bond with prior application of Temp Bond) and 16.34 +/- 5.02 MPa (dual use of ART Bond with intermediate application of Temp Bond). With respect to the surface treatment significant differences between the DBA's could be found in all groups.

Analysis of Variance↗
PubMed1996

Dentin bonding: SEM comparison of the resin-dentin interface in primary and permanent teeth.

Previous studies have suggested minor differences between primary and permanent teeth in terms of dentin composition and morphology. Other reports indicated lower bond strengths of resin composites to dentin of primary teeth compared with dentin of permanent teeth; however, no information is available regarding differences in the micromorphology of the resin-dentin interface that may explain these lower bond strengths. Therefore, the purpose of the present study was to compare primary and permanent teeth in terms of the thickness of the hybrid layer developed with two bonding systems. Our hypothesis was that bonding differences previously reported between primary and permanent dentin would be reflected in hybrid layer differences observable in SEM analyses. Twenty human extracted and non-carious teeth were divided into 4 groups: 5 primary and 5 permanent teeth restored with All-Bond 2/Bisfil P system; and 5 primary and 5 permanent teeth restored with Scotchbond Multi-Purpose/Z100. The sample area available on each tooth was divided for the two dentin conditioning times (7 and 15 sec). Measurements of hybrid layer thickness were performed by means of SEM at x13,000. The results of this study indicated that the hybrid layer produced is significantly thicker in primary than in permanent teeth (p = 0.0001), suggesting that primary tooth dentin is more reactive to acid conditioning. No difference was observed in the hybrid layers produced by the two adhesive systems (p = 0.7920). The increased thickness of the hybrid layer in primary teeth (25 to 30%) and the subsequent lack of complete penetration of adhesive resin into previously demineralized dentin may contribute to the lower bond strengths to primary dentin reported in the literature. If a narrower hybrid layer more uniformly infused with resin is the goal of dentin bonding, it is concluded that a differentiated protocol for bonding to primary dentin (with shorter time for dentin conditioning) can be used as a means to reproduce the hybrid layer thickness seen in permanent teeth.

Acid Etching, Dental↗
PubMed1999

Effect of dentin primers containing N-methylolacrylamide or N-methylolmethacrylamide on dentin pretreatment.

The effect of experimental dentin primers containing N-methylolacrylamide (MEAA) or N-methylolmethacrylamide (MEMA) on the bonding of three commercial light-cured resin composite systems [Restorative Z 100 (Scotchbond), Palfique Estelite (Macbond) and Photo Clearfil A (Clearfil Photobond)] to etched dentin was investigated. Water solutions of 35% hydroxyethyl methacrylate (HEMA). 50% MEAA or 30% MEMA were used as dentin primers. The dentin etched with 10% phosphoric acid solution was pretreated with dentin primers for 30 s. The resin composite systems were applied in a Teflon tube positioned onto pretreated dentin surfaces. After water immersion for 1 day, the shear bond strengths were measured. The thicknesses of hybrid layers at dentin-resin interfaces treated with 6 mol/l HCl and 1% NaOCl were measured by scanning electron microscopy. The dentin primer pretreatment increased the bond strengths of all resin composite systems. For Macbond and Clearfil Photobond, the bond strengths (14.2-26.5 MPa) with MEAA and MEMA were higher than those (10.5 and 17.8 MPa) with HEMA. All hybrid layer thicknesses were 1-1.5 microns after HCl immersion. The hybrid layers after NaOCl immersion become narrower. The main fracture pattern of specimens exhibiting high bond strengths (more than 14.2 MPa) was dentin cohesive fracture after bond test. For Macbond and Clearfil Photobond, the layers of specimens pretreated with MEAA and MEMA were clearly thicker than those pretreated with HEMA after NaOCl immersion. MEAA and MEMA solutions were more effective in improving the bond strength of Macbond and Clearfil Photobond to etched dentin than was HEMA. Macbond and Clearfil Photobond created good hybrid dentin layers which could resist NaOCl-attack when MEAA and MEMA solutions were used as dentin primers.

Acrylamides↗
PubMedDate not supplied

Porcelain to dentin bond strength with a dentin adhesive.

Adhesion of porcelain to dentin may be important in those cases with little remaining enamel. The purpose of this study was to determine the bond strength of porcelain to dentin using a dentin adhesive (All-Bond) and compare it to the enamel bond strength. Sixty human molar teeth had either a dentin or enamel bonding site prepared by flat grinding to a 600 grit. The teeth were divided into three groups of 20 each. Sixty porcelain cylinders were prepared, hydrofluoric acid etched on one end and silane treated. Twenty of the cylinders were bonded to enamel, 20 bonded to dentin with a dentin adhesive to be tested at 48 hours, and 20 bonded to dentin with a dentin adhesive to be tested after 24 hours of thermocycling (800 cycles at 6 degrees C to 60 degrees C). The specimens were tested in an Instron at a crosshead speed of 0.5 mm/minute. The following bond strengths were found: enamel (19.0 +/- 2.9 MPa), dentin at 48 hours (14.4 +/- 5.4 MPa), and dentin after thermocycling (10.1 +/- 3.8 MPa). When this data was subjected to statistical analysis (ANOVA), there was a significant difference between the groups. A Scheffe's test found that the dentin-porcelain bond at 48 hours was stronger than the thermocycled group, and that the enamel bond was significantly stronger than the two dentin bonds.

Analysis of Variance↗
PubMedDate not supplied

[Effect of remaining dentine thickness beneath deep cavities on the rate of reparative dentine formation--experimental study].

The aim of this study was to investigate the effect of remaining dentine thickness beneath deep cavities on the rate of reparative dentine formation throughout 119 days and to establish the limit value of the remaining dentine thickness that enables greatest amount of tertiary dentine in dogs' teeth. Deep buccal cavities were prepared in all canines and molars of three dogs, lined with four different lining materials for indirect pulp capping and filled with silver amalgam. Tetracycline labelling technique was used to demark the layers of reparative dentine produced during the experimental period of 17 weeks. After sacrificing and isolation the teeth from the jaws slices (1 mm thick) were cut off through the middle of the cavity, perpendicular to the cavity floor and mesio-distal tooth axis. Sections were ground to 100 microns thick; the measuring of the remaining and reparative dentine thickness was carried out with Fluoval, Carl-Zeiss, Jena, DDR fluorescent microscope. The results showed: 1. Cavity depth had a strong effect on the quantity of newly formed tertiary dentine; 2. The greatest rate of reparative dentine (348 microns) was produced beneath the cavities with remaining dentine thickness ranging 501-700 microns; 3. The least quantities of tertiary dentine (219 and 227 microns) were produced beneath the deepest cavities, with remaining dentine thickness less than 500 microns, as well as beneath shallower cavities with remaining dentine thickness of over 900 microns.

Animals↗