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Biomedical subjects

J R Boj

Publications and source records attributed to J R Boj.

12 recordsLinked to original sources
PubMed2003

The acute nephrotoxicity of systemically administered formaldehyde in rats.

AIM: The purpose of this study was to assess the acute nephrotoxicity of formaldehyde, as it is believed to be the toxic component of formocresol. METHODS: A sample of 24 Sprague-Dawley rats was used in the study and divided into 3 groups of 8 rats each. The following procedures were performed: group A) formaldehyde equivalent dose to 20 pulpotomies, injected into the main vein of each rat's tail; group B) formaldehyde equivalent dose to 100 pulpotomies injected; group C) control group with a saline solution injected. Blood analyses were performed after 24 and 48 hours to assess urea and creatinine levels. Urine samples were taken after 24 hours to analyse for LDH protein levels. Rats were sacrificed after 48 hours and histology samples of renal tissue were studied for any pathological defects. RESULTS: Evaluation of histological samples of kidney tissue did not show any inflammation or other tissue lesions. No significant differences were found, using an ANOVA test procedure, among the variables of LDH protein or creatinine levels after 24 and 48 hours. Significant differences were found between the levels of urea and creatinine after 48 hours between the control group and the other test groups. CONCLUSION: The use of formaldehyde at the usual clinical doses or with an amount equivalent to 100 pulpotomies did not produce renal tissue damage and the blood and urine factors analysed did not show significant changes after 48 hours in the experimental model used.

Animals↗
PubMed2000

Effect of different prophylaxis methods on sealant adhesion.

The objective of this study was to evaluate the retention of a light-cured sealant using previously different prophylaxis methods and two different etching times, thirty and fifteen seconds. Eighty, third molars surgically extracted were sectioned into two halves (buccal and lingual). The teeth were divided into 8 groups of 20 samples each, according to prophylaxis type: pumice powder, fluoridated paste, sodium bicarbonate spray, and control (no prophylaxis); and etching time: 30 and 15 seconds. Tensile bond strengths were studied using a universal Instron testing machine. A statistical test ANOVA was used. No statistical differences were found when comparing both etching times, but when prophylaxis methods were compared a statistically significant higher retention was found in the sodium bicarbonate and fluoridated paste groups.

Acid Etching, Dental↗
PubMed1998

Microleakage of fissure sealants after occlusal enameloplasty and thermocycling.

This study evaluated the microleakage of a filled and an unfilled sealant after different occlusal surface treatments. A total of 120 human non carious extracted molars were cleaned with a water slurry of fine flour of pumice using Crescent Snap-On pointed brushes in a slow-speed hand piece. The teeth were divided at random into six groups of 20 teeth each; Group 1 pumice prophylaxis and PrismaShield filled sealant; Group 2 pumice prophylaxis and Delton opaque unfilled sealant; Group 3 treatment with a diamond fissure bur (Sorensen Ponta K.G. 2137 F) and PrismaShield sealant; Group 4 treatment with a diamond fissure bur (Sorensen Ponta K.G. 2137 F) and Delton opaque sealant; Group 5 treatment with a 1/4 round carbide bur and PrismaShield sealant; and Group 6 treatment with a 1/4 round carbide bur and Delton opaque sealant. Before sealant placement, the enamel occlusal surfaces were acid-etched for 30 seconds using disposable brushes, rinsed, and dried. The sealants were light-cured for 40 seconds. Immediately after curing the sealant, 60 teeth were placed in distilled water for 48 hours and 60 teeth were thermocycled (500x, at 5 degrees C - 55 degrees C, dwell time 30 seconds) and evaluated for microleakage. Wilcoxon and Fisher's Exact Test revealed no statistical significant difference in microleakage between the thermocycled and non-thermocycled groups, between the fissure treatment modalities or between the filled and unfilled sealants.

Bisphenol A-Glycidyl Methacrylate↗
PubMed1997

Pulpal tissue reaction to formocresol vs. ferric sulfate in pulpotomized rat teeth.

The purpose of this study was to assess histologically the pulpal healing process after pulpotomies in rat teeth were done using two different agents: 20% dilution of formocresol (FMC) and ferric sulfate (FS). Two criteria were used: degree of inflammation and extent of pulpal involvement. Zinc oxide-eugenol paste (ZOE) or polycarboxylate cement (PCX) were placed to seal the cavity preparations. The maxillary first molars of 120 Sprague-Dawley rats were treated in this study and were divided into four groups: 1) FMC + ZOE, 2) FS + PCX, 3) FMC + PCX, and 4) FS + ZOE. After treatment the animals were sacrificed at weekly intervals for four weeks and pulpal response was evaluated according to the degree of inflammation. Other criteria were also evaluated: dentinal bridge formation, reparative dentin and odontoblastic layer. A Friedman test was performed to compare the results and find out if any differences could be found. FMC + ZOE group showed the least pulpal inflammation response, and the use of FS as an alternative agent for pulpotomies did not improve pulpal response.

Animals↗
PubMed1997

Bond strength and interfacial morphology of adhesives to primary teeth dentin.

PURPOSES: To evaluate (1) the shear bond strength to the dentin of primary teeth and failure site of hydrophilic dentin bonding agents, (2) the interfacial micromorphology of these adhesives on primary teeth. MATERIALS AND METHODS: Seventy-six primary noncarious molars stored in distilled water were obtained. The teeth were cleaned with pumice and a rubber cup. The mesio-buccal surface of the teeth was ground flat with hand pressure with a series of SiC paper ending with the 600 grit to provide a uniform surface on superficial dentin to which the adhesives and resin composite could be applied. After preparing the dentin surface, the teeth were stored in distilled water for 48 hours. They were then rinsed and dried with compressed air and divided at random into four groups of 16 specimens each: Group 1: Dentastic; Group 2: One-Step; Group 3: Prime & Bond 2.0; Group 4: Compoglass SCA. Z100 resin was used in all groups. All specimens were thermocycled (500x) and sheared in an Instron machine. After shear testing, the debonding sites of all samples were examined with a stereomicroscope and selected samples were also examined with the scanning electron microscope. Three additional samples per group were used to evaluate the resin adaptation to dentin. RESULTS: The results in MPa were: Dentastic 19.62 (4.67); One-Step 11.24 (3.67), Prime & Bond 22.38 (6.47), Compoglass SCA 18.88 (4.04). ANOVA (P < 0.0001) revealed that there was a significant difference between the groups. The Student-Newman-Keuls test (P < 0.05) showed no statistically significant difference between Dentastic, Prime & Bond and Compoglass SCA. However, these three groups were statistically significantly higher than One Step. In the Dentastic group, 14 of 16 samples revealed resin cohesive failure (resin fracture) while two of 16 displayed dentin cohesive failure (dentin fracture). In the One Step group, 15 samples failed at the resin and one sample showed dentin cohesive failure. In the Prime & Bond group, 12 specimens revealed resin cohesive failure while four displayed dentin cohesive failure. In the Compoglass SCA group, 13 samples had resin cohesive failures while three had dentin cohesive failures. All samples revealed an intimate adaptation to the dentin displaying resin tag formation.

Acid Etching, Dental↗
PubMed1996

Fissure micromorphology and sealant adaptation after occlusal enameloplasty.

This study evaluated fissure micromorphology after enameloplasty, and the effect of thermocycling on the adaptation of enamel surfaces of filled and unfilled sealants after different occlusal surface treatments. A total of 150 human noncarious extracted molars were cleaned with a water slurry of fine flour of pumice using Crescent Snap-On pointed brushes in a slow-speed handpiece. The teeth were divided at random into six groups of 20 teeth each: Group 1: Pumice prophylaxis and PrismaShield filled sealant; Group 2: Pumice prophylaxis and Delton opaque unfilled sealant; Group 3: Treatment with a diamond fissure bur (Sorensen Ponta K.G. 2137 F) and PrismaShield sealant; Group 4: Treatment with a diamond fissure bur (Sorensen Ponta K.G. 2137 F) and Delton opaque sealant; Group 5: Treatment with a 1/4 round carbide bur and PrismaShield sealant; Group 6: Treatment with a 1/4 round carbide bur and Delton opaque sealant. Before sealant placement, the enamel occlusal surfaces were acid-etched for 30 seconds using disposable brushes, rinsed and dried. The sealants were light-cured for 40 seconds. Immediately after curing the sealant, all teeth were placed in distilled water for 48 hours. Sixty teeth were thermocycled (x 500, 5 degrees C-55 degrees C, 30-second dwell time) and 60 teeth were not thermocycled. For each treatment modality, five additional teeth served as controls and did not receive the sealant. The results revealed a superior sealant adaptation to enamel when the enameloplasty technique was used. There was no difference in penetration capabilities and adaptation between the filled and the unfilled sealants or between the thermocycled or not thermocycled groups.

Dental Bonding↗
PubMed1993

Bond strength of resin-reinforced glass ionomer cements after enamel etching.

This study evaluated the shear bond strength of resin-reinforced glass ionomers to enamel etched or unetched. Human, non-carious extracted permanent molars stored in distilled water were used. Flat buccal and lingual enamel surfaces were ground wet on 600-grit silicon carbide paper. The teeth were then distributed at random into six groups of 5 teeth (10 surfaces) each: Group 1: Fuji II LC, no enamel etching; Group 2: Fuji II LC, enamel etched with 10% phosphoric acid for 10 seconds; Group 3: Dyract, no enamel etching; Group 4: Dyract, enamel etched with 10% phosphoric acid for 10 seconds; Group 5: Photac-Fil, no enamel etching; Group 6: Photac-Fil, enamel etched with 10% phosphoric acid for 10 seconds. Cylindrical samples of the glass ionomers were prepared in plastic molds and bonded to the enamel surface according to the manufacturers' instructions. All samples were placed in distilled water for 24 hours, and sheared with an Instron at a crosshead speed of 0.5 mm/minute. The results (in MPa) were: Group 1: 11.29 +/- 4.84; Group 2: 19.64 +/- 5.43; Group 3: 8.26 +/- 3.61; Group 4: 22.04 +/- 5.40; Group 5: 2.05 +/- 3.05; Group 6: 9.12 +/- 6.61. ANOVA and Student-Newman-Keuls procedure revealed that on etched enamel, Fuji II LC and Dyract had a significantly higher bond strength than all the other groups tested (P < 0.0001), but not significantly different between each other. With these two groups, cohesive failure within the material was recorded in all samples while in the unetched samples, all specimens displayed an adhesive failure (glass ionomer-enamel interface). All samples with Photac-Fil, with or without enamel etching had adhesive failures.

Acid Etching, Dental↗
PubMed1993

Dentures for a 3-yr-old child with ectodermal dysplasia: case report.

A case of a 3-year-old boy with X-linked hypohidrotic ectodermal dysplasia is presented. Complete maxillary and mandibular dentures were made at 3 years and 2 months of age. The process for making the dentures is described. Obtaining enough patient cooperation and proper application of behavioral management techniques are critical factors for the procedure described in the article.

Anodontia↗
PubMedDate not supplied

A study of behavior modification for developmentally disabled children.

A tape-slide series, using a desensitization and modeling approach, was developed in order to prepare three- and four-year-old developmentally disabled children for an initial dental examination. The tape-slide series pleasantly describes what to expect during the first visit to the dental office. A clown and a four-year-old girl were used as models. Twenty-eight children participated in the study, divided into two groups: control and experimental. A requirement for qualification as a patient was that the child not have had any previous dental experience. Three techniques for measuring behavior were used: heart rate, a modified Melamed's scale, and a dentist's subjective evaluation. The results demonstrated that: a) The experimental group was in a high state of arousal when starting the dental procedures; b) Children exposed to the tapeslide series showed worse behavior and a higher heart rate than children not exposed to the series; c) Heart rate was sensitive and objective in measuring anxiety and arousal in the dental setting; d) Modified Melamed's scale was not sensitive enough to measure microbehavior in this study; e) The subjective dentist's evaluation showed the impossibility of preventing a biased interpretation of behavior by the evaluator.

Analysis of Variance↗
PubMedDate not supplied

Differences between normal and developmentally disabled children in a first dental visit.

Twenty-eight three- and four-year-old normal children participated in a study where they were exposed to a tape-slide series before a first dental examination. The audiovisual product gives an explanation about a first examination, the children having no previous dental experience. The purposes of the study were to evaluate the behavior modification that took place and to see whether differences could be found with the results of the same study performed four years before, with developmentally disabled children. The results obtained with normal children were the opposite of those obtained with special children. The normal population subjected to the audiovisual technique behaved better and had a lower heart rate throughout the appointment.

Audiovisual Aids↗
PubMedDate not supplied

Surface hardness of a resin composite cured with a transparent cone.

The purpose of this study was to evaluate the surface hardness of a resin composite (TPH) polymerized with and without the use of a transparent light-curing cone. Twenty composite blocks were made on a Teflon mold with cylindrical holes of 3 mm depth and 6 mm radius, and were light cured following different procedures. Group 1: Ten samples were pressed with a glass slide and light cured for two 40-sec exposures without the plastic cone; Group 2: Ten samples were light cured using the transparent plastic cone which was pressed down into the composite until the tip was 1 mm from the floor of the cylindrical Teflon mold. The curing light was activated for 40 sec. The cone was then removed and the remaining part of the mold was filled in one portion, pressed with a glass slide, and light cured for 40 sec. After curing, the samples were placed in distilled water for 48 hr. The hardness of the samples was then measured with a Rockwell Hardness Tester at three different points on each composite block; therefore, 30 measurements per group were taken. The data were statistically analyzed using an unpaired Student's t test. The results revealed that the resin composite cured with the transparent plastic cone had a statistically significant higher surface hardness value (P < 0.0001) than the group cured without the cone.

Composite Resins↗