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PubMed1999

Scanning electron microscope study on the efficacy of root canal wall debridement of hand versus Lightspeed instrumentation.

AIM: The aim of this in vitro study was to compare the efficacy of root canal wall debridement following hand versus LightSpeed instrumentation. METHODOLOGY: Twenty recently extracted single-rooted teeth were paired and randomly placed into two treatment groups of 10 teeth each. In group 1, a step-back instrumentation without initial coronal flaring with stainless steel Hedstroem files was used; group 2 was instrumented with Ni-Ti LightSpeed instruments. Both groups had the same irrigation regimen: 2.5% NaOCl and a 15% EDTA solution. The teeth were then decoronated and each root split longitudinally into two halves to be examined using the scanning electron microscope (SEM). The presence of superficial debris and smear layer was evaluated by a standardized grading system, and the resulting scores submitted to nonparametric statistics. RESULTS: Under the conditions of this study, the removal of superficial debris was generally excellent with both canal preparation techniques. Both techniques resulted in variable presence of residual smear layer, with a canal wall covered by smear layer as the predominant characteristic. Generally, the amount of smear layer was greater in the apical than in the middle third of the root, however, this difference was statistically significant (P < 0.005) only in hand-instrumented teeth. The use of LightSpeed instruments was associated with significantly more (P < 0.05) smear layer presence in the middle region of the root when compared with hand instrumentation. In addition, less smear layer was present in the apical region following LightSpeed instrumentation than stainless steel hand files, but this difference was not statistically significant. Differences in debridement between the two halves of the same root were more evident with LightSpeed than manual instrumentation, however, there was no statistical significance. CONCLUSIONS: It may be inferred that the choice between hand and LightSpeed instrumentation should be based on factors other than the amount of root canal debridement, which does not vary significantly according to the instruments used.

Aged↗

PubMed2002

Scanning electron microscopic and energy dispersive spectrometric investigations on the effect of XeCl excimer laser on human dentin with smear layer.

The purpose of this study was to study the effect of XeCl excimer laser on smear layer covered dentine of extracted human teeth. Twenty-four freshly extracted human molar teeth were collected and randomly divided into one control group and three experimental groups of six teeth each (groups A-D). The teeth in the experimental groups were irradiated with XeCl 308-nm excimer laser at a fluence of 0.4 J cm-2 and a constant pulse repetition rate of 25 Hz. Group A was used as the control, while groups B, C and D were irradiated at different exposure times of 3, 5 and 7 s, respectively. Subsequently these teeth specimens were subjected to scanning electron microscopic (SEM) examination and energy dispersive X-ray (EDX) spectrometric analysis. The SEM examination revealed melting of the smear layer covered dentin to conceal the underlying dentinal tubules. At a longer exposure time (7 s), dentin melted to form large grains and this resulted in non-uniform closure of underlying dentinal tubules. Under the conditions of this study, it is concluded that the pulsed XeCl 308-nm excimer laser at a fluence of 0.4 J cm-2, with an exposure time of 5 s uniformly occluded exposed smear layer covered dentine with no conspicuous variation in chemical structure.

Calcium↗

PubMedDate not supplied

Acute morphological changes in guinea pig cochlea following electrical stimulation. A preliminary scanning electron microscope study.

A major area of concern in the development of the cochlear prosthesis involves the effects of the implant on inner ear anatomy and function. This study examined one aspect of host-implant interaction- the effects of cochlear implantation with and without electrical stimulation on cochlear morphology in the guinea pig. To accomplish this, a series of normal guinea pigs were acutely implanted bilaterally with a scala tympani multiple electrode prosthesis. One ear was stimulated with continuous 1 kHz sinusoidal current of constant intensity for a period of three hours. The contralateral control ear was not stimulated. Current intensities tested ranged from 0.1 mA to 1 mA rms. After stimulation the animals were sacrificed, perfused with fixative and the temporal bones were microdissected for examination using the scanning electron microscope. Morphological changes observed in the stimulated ear ranged from hair cell and supporting cell degeneration to complete destruction of the basilar membrane and organ of Corti overlying the electrode. These changes occurred at current intensities ranging from 0.4 mA to 1 mA and were conspicuously absent in the implanted but unstimulated control ears. The current intensities employed in this experiment were within operating ranges presently used in long-tern behavioral studies in other animal models. To what degree the morphological changes observed in this study may effect the function of the prosthesis or host responses on a long-term basis cannot be determined from this experiment. However, our observations do demonstrate that electrical stimulation of the cochlea is not benign and point out the need for further evaluation to help define safe standards for use of the prosthesis.

Animals↗

PubMed1982

A scanning electron microscopic investigation of effects of prostacyclin on platelet retention in glass bead columns.

As whole blood passes through a column of glass beads, platelets are activated and all 3 basic platelet properties (adhesion, release reaction and aggregation) displayed, an aspect similar to platelets being involved in a hemostatic process. For this reason, we chose the platelet retention test as the tool to study the effect of synthetic prostacyclin (PGI2) on platelet function and behavior. PGI2 inhibited platelet retention with its major impact on platelet aggregation. The extent of inhibition was not proportional to the concentration of PGI2. It appears that 2 levels of platelet aggregation take place inside the column. One, triggered by a weak stimulus, is readily inhibitable by low concentrations of PGI2. The other, brought about by a strong stimulus, requires higher concentrations of PGI2 to achieve complete inhibition. Even with as much as 100 ng PGI2/ml blood, a 15% retention remained which probably represented platelet adhesion to glass beads. Scanning electron microscopic examination of glass beads showed massive platelet aggregation and adhesion in control blood samples. No platelet aggregate was observed on beads filtered with blood containing 20 ng/ml or more PGI2. Individual platelets were found on glass beads filtered with samples containing any concentrations of PGI2; these platelets exhibited extensive morphologic changes.

Blood Platelets↗

PubMed1992

Immunocytochemical and scanning electron microscopic studies of atherosclerosis in Japanese quail.

The major cellular components of atherosclerotic lesions in several species have been shown to be smooth muscle cells (SMC) and macrophages. Many studies suggest the composition of a lesion varies depending on the stage of lesion development. For example, macrophages are believed to be involved in the initial events of fatty streak formation in many animals. This communication presents the first cellular study of quail atherosclerosis and demonstrates the alteration of cellular structure during the process of the disease in quail fed a cholesterol diet. Monoclonal antibodies to alpha-actin and chicken macrophages effectively identified the presence of SMC and macrophages, respectively, as constituents of the atherosclerotic lesions. Macrophage presence, as well as SMC proliferation, was observed in early lesions. Although the first cell type to be involved in the initial stages of atherogenesis cannot be defined, the results suggest early intervention of macrophages and SMC. Scanning electron microscopic examination of the aortic arch demonstrates the obvious differences in appearance of the endothelial surface of normal and diseased quail. The accumulation of subendothelial foam cells causes the lumen surface to bulge irregularly into the lumen. The results of the present study are important to the evaluation of the key cellular events of atherogenesis.

Animals↗

PubMed1996

Applications of the environmental scanning electron microscope to the analysis of pharmaceutical formulations.

Electron microscopy has been used for several years as a routine tool for the study of pharmaceutical formulations. However, it is usually desirable to obtain information on these systems in the wet state, and there are concerns regarding the interpretation of information provided by conventional electron microscopy where samples are subjected to preparation techniques which may include freezing, drying, fracturing, and coating. The environmental scanning electron microscope (ESEM) has been used to analyse a number of pharmaceutical samples in their natural state. Results obtained from these samples, including biodegradable matrices, microparticulate systems (both degradable and non-biodegradable), and bioadhesive matrices, will be discussed and the merits and limitations of the ESEM will be highlighted.

Anhydrides↗

PubMed1993

The otolithic organ in the developing chick embryo. Scanning electron microscopic study on the utricular macula.

The long and short axes of utricular maculae were measured to calculate growth curves using an ocular micrometer under stereomicroscope. The mean lengths of the long and short axes on the 6th incubation day were 0.06 mm and 0.05 mm, respectively. Thereafter: 1.00 mm and 0.74 mm on the 11th incubation day; 1.34 mm and 1.03 mm on the 15th incubation day; and on hatching 1.51 mm and 1.07 mm, respectively. The surface structure, particularly the otoconia and the sensory hairs of the utricular maculae, on the 4.5th incubation day to the 7th post-hatching day of White Leghorn chicks were observed with a scanning electron microscope (SEM). A number of microvilli and primary cilium on the inner surface of the otocyst were found between the 4.5th and the 5th incubation day. Immature sensory hairs appeared on the 5th incubation day. The polarity of the sensory hairs became evident on and after the 9th incubation day. Mature sensory hairs were seen all over the utricular maculae between the 1st and the 3rd post-hatching day. Mature sensory hairs were mainly seen near the striola, and immature ones peripherally. Then, the various forms in the maturation phase of sensory hairs were seen between the striola and the periphery. These arrangements suggest some process of maturity from the peripheral region to the central striola region. Immature otoconia were first seen on the 6th incubation day. Mature otoconia were recognized on and after the 11th incubation day, and they were observed on the whole surface of the utricular maculae. Global substances on the macula with a rough surface and spongy structure were observed suggesting otoconial precursors transforming themselves into otoconial crystals.

Animals↗

PubMedDate not supplied

[A study of different polishing techniques for amalgams and glass-cermet cement by scanning electron microscope (SEM)].

Finishing and polishing an amalgam restoration, is considered as an important and necessary step of the restorative procedure. Various polishing techniques have been recommended to success a smooth amalgam surface. The aim of this study was to investigate the influence of three different polishing treatments on the marginal integrity and surface smoothness of restorations made of three commercially available amalgams and a glass-cermet cement. The materials used were the amalgams, Amalcap (Vivadent), Dispersalloy (Johnson and Johnson), Duralloy (Degussa) and the glass-cermet Katac-Silver (ESPE). The occlusal surfaces of the restorations were polished by the methods: I) round bur, No4-rubber cup-zinc oxide paste in a small brush, II) round bur No 4-bur-brown, green and super green (Shofu) polishing cups and points successively and III) amalgam polishing bur of 12-blades-smooth amalgam polishing bur. Photographs from unpolished and polished surfaces of the restorations, were taken with scanning electron microscope, to evaluate the polishing techniques. An improvement of marginal integrity and surface smoothness of all amalgam restorations was observed after the specimens had been polished with the three techniques. Method II, included Shofu polishers, proved the best results in comparison to the methods I and III. Polishing of glass-cermet cement was impossible with the examined techniques.

Cermet Cements↗

PubMed1990

[A scanning electron microscope study comparing the cleansing effect of the irrigating solutions and irrigating systems].

The purpose of this study was to compare the effect of various irrigating solutions and irrigating debris and the smear layer from the walls of instrumented root canals. 20 single-rooted teeth were biomechanically instrumented to size 40 K-file using sterile saline. And then the teeth were divided into 4 groups and 5 teeth in each group. Groups were irrigated as follows: Group 1: Teeth were irrigated with 20 ml of sterile saline. Group 2: Teeth were irrigated with 10 ml of 3% H2O2 and 10 ml of 2.5% NaOCl using the syringe. Group 3: Teeth were irrigated with 10 ml of 3% H2O2 and 10 ml of 2.5% NaOCl using the ENAC. Group 4: Teleth were irrigated with 10 ml of 17% EDTA and 10 ml of 2.5% NaOCl using the Endo-mate. All specimens were viewed at the cervical, middle, and apical thirds of the root canals for evaluation of the cleaning effect with the scanning electron microscope. The results were as follows: 1. The Endo-mate with EDTA and NaOCl solutions was the most efficient in cleaning the cervical and middle thirds of the root canal. 2. There was no difference between the irrigating solutions and irrigating systems in the cleaning effect at the apical third of the root canal.

Edetic Acid↗

PubMed1997

Scanning electron microscopic evaluation of the cleanliness of a new ultrasonic root end preparation.

Recently introduced ultrasonic instrumentation techniques for root end preparation have revolutionized the field of endodontic surgery. The specially designed tips offer improved access to the root end and create more conservative root and preparations while decreasing the amount of retained debris. This study compared the cleanliness of root end preparations made using ultrasonic instrumentation with that of those prepared in a traditional manner using a microhandpiece bur. We used 10 extracted maxillary human premolars and molars. After cleaning, shaping, and obturation of the root canals, a 3 mm root end resection perpendicular to the long axis of the root was performed with a carbide fissure bur. The roots were randomly divided into two groups and root end preparations were made using the two aforementioned techniques. The roots were longitudinally split and sputter-coated with gold for scanning electron microscopic study. Three independent dentists used a standardized grading system to evaluate the cleanliness of the root end preparations. The ultrasonic preparation had significantly less superficial debris and a thinner smear layer than the microhandpiece preparation (p < 0.05). There were no significant differences between the canal and isthmus portions of the root end preparations within each group in either superficial debris or smear layer. This indicates that cleaner surfaces for root end cavities are created using ultrasonic retrotips than using microhandpiece burs.

Dental Pulp Cavity↗

PubMed1979

[Morphological changes of platelets in disturbed cerebral microcirculation--a clinical study using a scanning electron microscope (author's transl)].

Many factors are known that contribute to the pathogenesis of the cerebral microcirculatory disturbances, but, there are few reports investigating the roles of the intravascular components directly. The present study was undertaken to evaluate morphological changes of platelets in patients with cerebral damage, in relation to neurological signs, especially consciousness levels. Morphological changes of platelets were observed in 72 patients with intracranial organic lesions. These lesions included subarachnoid hemorrhages, hypertensive cerebral hemorrhages, cerebral infarctions, brain tumors, chronic subdural hematomas, and acute epidural hematomas. Two blood samples were taken, one from the internal jugular vein (the blood after cerebral perfusion), the other from the cubital vein (systemic blood). After fixative procedures with 1% glutaraldehyde, the differences in the three-dimensional structures of platelets were compared, using a scanning electron microscope. In general, remarkably activated forms of platelets were found in the blood after cerebral perfusion in cases with severely impaired consciousness in the acute stage. But, in cases without severe neurological deficits, such changes of platelet forms were rarely seen. A close relationship was suggested between the degree of neurological damage (especially consciousness levels) and that of platelet activation in the acute stage. In the chronic stage, these changes of platelets in the cerebral blood disappeared. Changes of platelet forms were not found in the systemic blood from the cubital vein, even in the acute stage. It is clinically suggested that morphological changes of platelets play an important role in the pathogenesis of the disturbed cerebral microcirculation. Obstruction of cerebral microvasculature may be caused, mechanically by the activated platelets themselves, and/or chemically by vasoconstrictive substances released from these platelets. Therefore, in the treatment of these intracranial organic lesions, it is concluded that the possible roles of activated platelets should be taken into consideration.

Adolescent↗

PubMed1998

A scanning electron microscopic study of the effect of Gluma CPS bonding system on dentinal smear layers produced by different bur types and rotational speeds and on the resin-dentin interface.

OBJECTIVE: The purpose of this study was to investigate the effect of conditioners on smear layers produced by different bur types and rotational speeds and to study the interaction of subsequently applied primer and sealer with these conditioned surfaces. METHOD AND MATERIALS: Smear layers were produced on human teeth immediately after extraction by burs rotating at approximately 6,000 rpm without water spray and 400,000 rpm with water spray. Gluma CPS etchant was applied for 15, 30, and 60 seconds, and a 20% phosphoric acid liquid (control) was applied for 30 seconds to smear layers. The specimens were prepared by critical point drying for scanning electron microscopic imaging within 24 hours. Additional specimens were prepared and treated with Gluma CPS primer and sealer, according to the manufacturer's instructions. RESULTS: There were only small variations in the smear layer thicknesses with different bur types or speeds of rotation. Gluma CPS conditioner, applied for the recommended times, did not completely remove the smear layer. An altered smear layer, composed of a reaction product, remained on the dentinal surface. A zone of demineralization did occur, however, beneath the partially removed smear layer in both the 15- and 30-second specimens but was only partly filled by primer and sealer. Smear layers were completely removed by the 20% phosphoric acid liquid to expose a delicate collagen network. CONCLUSION: An understanding of the appropriate treatment for smear layers is crucial to the development of improved dentin bonding systems.

Acid Etching, Dental↗

PubMed2003

Evaluation of canal cleanliness and smear layer removal after the use of the Quantec-E irrigation system and syringe: a comparative scanning electron microscope study.

OBJECTIVE: The purpose of this study was to evaluate canal cleanliness and smear layer removal after use of the Quantec-E irrigation system and to compare the system with traditional irrigation. STUDY DESIGN: Forty anterior teeth were randomly assigned to 4 groups. Group A consisted of 15 teeth that were instrumented with .12, .10, .08, .06 and .04 tapered rotaries while simultaneously irrigated via the Quantec-E irrigation pump with 12 mL of 5.25% NaOCl, followed by 6 mL EDTA 17% in crown-down fashion, with a final flush with 4 mL 5.25% NaOCl. Group B consisted of 15 teeth that were instrumented with the same instrument sequence, and irrigated with the same volumes via traditional needle and syringe. Group C consisted of 5 teeth that were sectioned and examined under a scanning electron microscope (SEM) without any instrumentation and served as a negative control. Group D consisted of 5 teeth that were instrumented dry, without any irrigation, and served as a positive control. All teeth were sectioned buccolingually and examined with SEM at 700x magnification in the apical, middle, and coronal portions of the canals. Analysis of SEM images was performed by 5 independent examiners using a 4-point scoring system. RESULTS: Irrigation with the Quantec-E irrigation pump resulted in cleaner canal walls, less debris, and more complete removal of the smear layer within the coronal one third, when compared with syringe irrigation. However, no difference was observed in the middle and apical one thirds of the root canal. CONCLUSION: There was no significant difference between the 2 irrigation systems.

Dental Pulp Cavity↗

PubMed2000

Influence of multiple use of Timedur-titanium cannon drills: thermal response and scanning electron microscopic findings.

Multiple use of dental drills is known to raise drilling temperatures. Therefore, to minimize surgical trauma, well sharpened drills are recommended. In order to evaluate surgical trauma due to multiple use, 20 Timedur cannon drills (ZL-Duraplant-Implant-System) were used 51 times in an in vitro experimental setting using pigs' mandibles. Preparations of implant sites were performed with cannon drills at a maximum rotational speed of 1200 r.p.m. with low pressure and water irrigation. Drills were divided randomly into 3 groups and were treated differently after each preparation: 10 cannon drills were cleaned only with distilled water (group 1), 5 cannon drills were disinfected with Secudrill and autoclaved (group 2) and 5 cannon drills were cleaned with Instrument Detergent MIS 027 and autoclaved (group 3). Temperature measurements were performed with a NiCrNi thermocouple placed 0.5 mm from the drilling site. The width of the cutting edge of the cannon drills was repeatedly examined by scanning electron microscope (SEM). Results revealed that temperatures measured at all times were below the bone injuring level. Drills reused more than 40 times stood out with an increased number of higher temperatures. Only autoclaved drills showed an increased width of the cutting edges. From the present investigation it can be concluded that cannon drills of the ZL-Duraplant System should not be re-used more than 40 times.

Analysis of Variance↗

PubMed2005

Effects of copper vapor laser radiation on the root canal wall of human teeth: a scanning electron microscope study.

OBJECTIVE: The aim of this study is to analyze the effects of copper vapor laser radiation on the radicular wall of human teeth. MATERIALS AND METHODS: Immediately after the crowns of 10 human uniradicular teeth were cut along the cement-enamel junction, a chemical-surgical preparation of the radicular canals was completed. Then the roots were longitudinally sectioned to allow for irradiation of the surfaces of the dentin walls of the root canals. The hemi-roots were separated into two groups: one (control) with five hemi-roots that were not irradiated, and another (experimental) with 15 hemi-roots divided into three subgroups that were submitted to the following exposure times: 0.02, 0.05, and 0.1 s. A opper vapor laser (510.6 nm) with a total average power of 6.5 W in green emission, frequency of 16.000 Hz, and pulse duration of 30 ns was used. RESULTS: The results obtained by scanning electron microscope analysis showed the appearance of a cavity in the region of laser beam impact, with melting, recrystallization, and cracking on the edges of the dentin of the cavity due to heat diffusion. CONCLUSIONS: We determined that the copper vapor laser produces significant morphologic changes in the radicular wall of human teeth when using the parameters in this study. However, further research should be done to establish parameters that are compatible with dental structure in order to eliminate thermal damages.

Copper↗

PubMed1991

Susceptibility of glucose-6-phosphate dehydrogenase deficient red cells to primaquine, primaquine enantiomers, and its two putative metabolites. II. Effect on red blood cell membrane, lipid peroxidation, MC-540 staining, and scanning electron microscopic studies.

The effects of primaquine (PQ), its enantiomers [(+)PQ,(-)PQ] and hydroxy metabolites [5-hydroxyprimaquine (5HPQ) and 6-desmethyl-5-hydroxyprimaquine (6D5HPQ)] on cell membranes of glucose-6-phosphate dehydrogenase (G-6-PD) deficient red cells were studied in vitro. There was no significant effect of PQ on the malonyldialdehyde (MDA) content of normal and heterozygous red cells, but it caused a significant increase in MDA in G-6-PD deficient red cells (P less than 0.05). There was no noticeable difference between the effects of the two enantiomers on this variable (P greater than 0.05). Compared to PQ, the hydroxy metabolites produced a significantly greater increase in MDA in all the groups studied (P less than 0.001). Of the two hydroxy metabolites, 6D5HPQ was more toxic than 5HPQ. Staining with MC540 showed that exposure to PQ, its enantiomers and two putative metabolites produced significant fluorescence, indicating that the drug produces marked alterations in membrane fluidity. Although the fluorescence was seen both in normal and heterozygous cells, the effect was marked in hemizygous deficient red cells (P less than 0.001). Scanning electron microscopic (SEM) studies revealed that PQ enantiomers had a stomatocytic effect on red cells of normal, heterozygous and hemizygous G-6-PD deficient red cells, whereas the putative metabolites had an echinocytic effect. The effects were most pronounced in G-6-PD deficient red cells.

Erythrocyte Membrane↗

PubMed2002

A scanning electron microscopic study of dentinal erosion by final irrigation with EDTA and NaOCl solutions.

AIM: The purpose of this in vitro study was to examine dentinal erosion caused by final irrigation with EDTA and NaOCl. METHODOLOGY: Twenty-five single-rooted human teeth were instrumented with rotary nickel-titanium Series 29 Profile Instruments. The teeth were divided into five groups and subjected to final irrigation as follows: group A, irrigated with 6% NaOCl (3 mL) for 2 min; group B, 15% EDTA (3 mL) for 1 min; group C, 15% EDTA (3 mL) for 1 min, followed by 6% NaOCl (3 mL) for 2 min; group D, 15% EDTA (3 mL) for 3 min and group E, 15% EDTA (3 mL) for 3 min, followed by 6% NaOCl (3 mL) for 2 min. Photomicrographs of dentinal walls were produced using a scanning electron microscope (3000 x) at 1, 3 and 6 mm from the apex. The amount of debris and dentinal tubule diameter were evaluated, and values were statistically analysed using one-way ANOVA and Fisher's PLSD test. RESULTS: When the root canal was irrigated with 15% EDTA alone, the dentine had a smooth and plane appearance, and dentinal tubule orifices were regular and separated. When the root canal was irrigated with EDTA followed by NaOCL the dentine was eroded and the dentinal tubule orifices were irregular and rough. Dentinal tubule diameter increased to 3.43 +/- 0.23 microm in group C and to 3.93 +/- 0.44 microm in group E. Significant differences were observed between groups B and C, and between groups D and E (P < 0.05). However, more debris was removed by irrigation with EDTA followed by NaOCl than with EDTA alone (P < 0.05). CONCLUSIONS: Final irrigation with 6% NaOCl accelerates dentinal erosion following treatment with 15% EDTA.

Analysis of Variance↗

PubMedDate not supplied

Comparative quantitative and qualitative assessment of the marginal adaptation and apposition of bonded amalgam restorations using luting glass ionomer and 4-META adhesive liner under a scanning electron microscope. An in vitro study.

The present invitro study was conducted to assess the marginal adaptation and apposition of amalgam restorations bonded to tooth structure, using freshly mixed luting glass ionomer cement (type 1) and compared with the much documented material--Amalgam bond (4-META). Twelve freshly extracted human premolar teeth were used and class V cavities were prepared on the buccal and lingual surfaces of twelve teeth for the experimental groups. Buccal cavities (class V) were prepared on twelve other teeth for the control group. In the control, two coats of cavity varnish was applied as the liner. The experimental groups were lined with freshly mixed luting glass ionomer in twelve buccal cavities and amalgam bond adhesive liner in twelve lingual cavities. The amalgam was then condensed before the liner sets in all the cavities. The teeth were sectioned and mounted on aluminum stubs and then placed in the scanning electron microscope and were observed. The results of the study showed that marginal interface gaps were higher with luting glass ionomer and cavity varnish than with amalgam bond as the liner. The results were statistically not significant. All the three groups were effected by the severe thermal stresses introduced by the microscopy with the glass ionomer cement suffering the worst. The present investigation confirms that glass ionomer cement (type 1) can be effectively used as a bonding agent between amalgam and the tooth when it is painted onto the cavity walls after which the amalgam is condensed immediately, prior to its setting. Its ability to bond amalgam to the tooth structure with minimal gaps is comparable to that of amalgam bond.

Acrylic Resins↗