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Biomedical subjects

Franklin Garcia-Godoy

Publications and source records attributed to Franklin Garcia-Godoy.

18 recordsLinked to original sources

Comparison of the clinical and preclinical biocompatibility testing of dental materials: are the ISO usage tests meaningful?

International Organization for Standardization (ISO 10993 and 7405) guidelines recommends the preclinical screening of dental materials using non-human primates. The literature contains no comparisons of responses to dental materials. To test the accuracy of preclinical screening tests for predicting human clinical responses, 106 class V pulp exposed cavities were prepared in human and non-human primate teeth. Teeth were restored with calcium hydroxide and amalgam, zinc oxide eugenol or resin-modified glass ionomer. Teeth were extracted after 10-163 days and prepared for histological analysis. Pulp cell numbers were compared and their reactionary dentin activity measured in response to cavity preparation. Pulp inflammatory activity was categorized according to ISO standards. There were no statistically significant differences between human and non-human primate teeth in terms of pulp reactions to dental materials. The use of non-human primates for preclinical biocompatibility investigation provided an accurate method of evaluating clinical responses to dental materials.

Adolescent↗

Micro-tensile bond strength of sound and caries-affected primary tooth dentin measured with original designed jig.

To measure the micro-tensile bond strength (MTBS) on sound and caries-affected primary tooth dentin using an original designed jig that was developed for making symmetric and uniformly-sized specimens for the micro-tensile strength testing. The MTBS of dumbbell-shaped specimens and matchstick-shaped specimens were measured. Dumbbell-shaped specimens: The occlusal surfaces of 15 sound primary molars were ground with a water-cooled air turbine using a diamond bur. The adhesive systems and resin-based composites were Clearfil SE Bond and Clearfil AP-X (SE group) and Single Bond and Z250 (SB group). Matchstick-shaped specimens: Sixteen primary molars (5 sound and 11 carious) were used. The occlusal surfaces of sound teeth were ground with a water-cooled air turbine using a diamond bur. Infected dentin was determined by a caries detecting dye solution and removed with a round-shaped steel bur under water-cooling and with a hand instrument. SE was applied. Data was statistically analyzed using ANOVA and Fisher's PLSD at p < 0.05. The MTBSs (MPa) for the dumbbell-shaped specimens were 8.9 +/- 7.0 in the SE group and 10.3 +/- 5.8 in the SB group and that for the matchstick-shaped specimens were 9.0 +/- 6.3 in the sound-SE group and 9.2 +/- 5.8 in the carious-SE group. No significant difference was observed among them.

Bisphenol A-Glycidyl Methacrylate↗

Effects of staining and bleaching on color change of dental composite resins.

STATEMENT OF PROBLEM: Discoloration of resin-based composites by colored solutions is a common problem. The use of bleaching agents for discolored natural teeth is becoming increasingly popular. It is not clear if bleaching agents can remove the stain from composite resins. PURPOSE: The purpose of this study was to investigate the effects of 2 staining solutions and 3 bleaching systems on the color changes of 2 dental composite resins. MATERIAL AND METHODS: Forty-five disk-shaped specimens (9 x 2.5 mm) of each of 2 composite resins, Filtek Supreme (FS) and Esthet X (EX), were prepared. The specimens were then divided into 3 groups of 15 specimens each and immersed in 2 staining solutions (coffee or red wine) or distilled water (control) for 3 hours daily over a 40-day test period. The 3 groups were then divided into 3 subgroups (n = 5), and 3 bleaching agents (Crest Night Effects, Colgate Simply White Night, or Opalescence Quick) were applied to the surface of the specimens over a 14-day period. Color of the specimens was measured with a spectrophotometer using CIELAB color space relative to CIE standard illuminant D55 at baseline, after staining, and after bleaching. The color differences (deltaE(ab)*) between the 3 measurements were calculated. The value deltaE(ab)* = 3.3 was used as an acceptable value in subjective visual evaluations. Analysis of variance and nonparametric analysis (Kruskal-Wallis test and Mann-Whitney test) were used to analyze the data. RESULTS: After staining, FS had more color change than EX and was more affected by the wine solution. After bleaching, the color of both EX and FS specimens returned to the baseline. The color differences between bleaching and baseline were less than value deltaE(ab)* = 3.3 for all groups. CONCLUSION: The nanocomposite (FS) changed color more than the microhybrid composite (EX) as a result of staining in coffee or red wine solutions. After bleaching, discoloration was removed completely from the composite resins tested.

Analysis of Variance↗

Influence of the amount of UV component in daylight simulator on the color of dental composite resins.

STATEMENT OF PROBLEM: Color of fluorescent substances is influenced by the amount of ultraviolet (UV) component in the illumination. Color of fluorescent dental composite resins may change by the amount of UV component in the ambient light, but there have been few studies on this subject. PURPOSE: The purpose of this study was to determine the differences in color and color parameters such as lightness, chroma, and hue of composite resins created by varying the amount of UV component of a pulsed-xenon source that is conditioned to approximate the Commission Internationale de l'Eclairage (CIE) standard illuminant D65. MATERIAL AND METHODS: A spectrophotometer, in which the UV component of a daylight simulator could be adjusted, was developed. Eight light-polymerized dental composite resins, A3 shade, were studied. Five disk-shaped specimens, 10 x 3 mm, were prepared for each material. Color of specimens was measured on a reflection spectrophotometer over a white background relative to 3 illuminations, which had the same spectral power distribution of the CIE standard illuminant D65 in visible range, but different UV component. D65 indicated the illumination in which the UV component of the pulsed-xenon source was adjusted to the CIE standard illuminant D65 using a UV adjustment tile. UV-EXC indicated the illumination in which the UV component of the source was excluded with a UV filter. UV-INC indicated the illumination in which the UV component was included. Differences in color parameters by the illumination were analyzed with repeated-measures 1-way analysis of variance (ANOVA) by the brand of composite resins. Differences in color (DeltaE*(ab)) and color parameters such as lightness (DeltaL*), chroma (DeltaC*(ab)), and hue angle (Deltah) were analyzed with 3-way ANOVA, with the independent variables of brand of composite resin, combination of illuminations, and type of color parameters (alpha = .05). RESULTS: Color differences (DeltaE*(ab)) by the amount of UV component in the illuminations ranged between 0.3 and 1.4 for D65 and UV-EXC, between 0.3 and 0.5 for D65 and UV-INC, and between 0.2 and 1.6 for UV-EXC and UV-INC. Based on the repeated-measures ANOVA, lightness was not influenced by the amount of the UV component in the illumination, however, chroma and hue angle were influenced by the amount of UV component. Based on the 3-way ANOVA, differences in color and color parameters (DeltaE*(ab), DeltaL*, DeltaC*(ab), and Deltah) by the amount of the UV component were influenced by all of the 3 factors, and there were significant interactions between all the combinations of factors (P < .05). CONCLUSION: Though there were significant differences in color and color parameters by the amount of the UV component in the D65-simulated xenon source, color difference caused by the UV component was lower than 1.6, which is in the visually acceptable range.

Analysis of Variance↗

Bond strength and failure patterns of adhesive restorations in primary teeth aged in the oral environment.

PURPOSE: To evaluate the bond strength and micromorphology of the fracture pattern of adhesive composite restorations in primary teeth after long-term clinical function. METHODS: Subjects (8-10 years-old) with deep carious lesions in primary molars had their teeth restored with resin composite (Z250). The teeth were randomly divided into two groups, according to the adhesive system used: (1) Scotchbond Multi-Purpose (SMP); and (2) Clearfil SE Bond (CSE). After the clinical and radiographic follow-up period (15-17 months), the teeth were exfoliated and the adhesive restorations were subjected to microtensile bond test. RESULTS: Student's t-test revealed a statistical difference (P= 0.001) between the two adhesive systems tested (SMP = 16.8 +/- 2.62 MPa; CSE = 27.3 +/- 2.28 MPa). The micromorphology evaluation of the failure zone revealed a weak area in the demineralized dentin (SMP) and at the top of the hybrid layer (CSE).

Child↗

Clinical evaluation of composite and compomer restorations in primary teeth: 24-month results.

PURPOSE: This split-mouth, blind study evaluated the clinical performance of Dyract AP, F2000, and Heliomolar placed in primary molars of 30 children (mean age, 6 years and 2 months). MATERIALS AND METHODS: From a total of 79 restorations accomplished, 27 were built with Heliomolar (18 Class I, and 9 Class II), 30 were with F2000 (21 Class I and 9 Class II), and 22 were built with Dyract AP (14 Class I and 8 Class II). All of teeth restored had primary caries lesions. At 6, 12, 18 and 24 months, 60 restorations (75%) were evaluated using USPHS criteria for: color match (CM), marginal adaptation (MA), marginal discoloration (MD), anatomic form (AF) and secondary caries (SC) by three calibrated operators. The Alpha+Bravo score percentage was considered as clinical success. The data were subjected to statistical analysis by Mann-Whitney and Kruskal-Wallis tests (p<0.05). RESULTS: Heliomolar showed the smallest success clinical at 12 months for marginal adaptation and secondary caries, and at 18 months for marginal discoloration. Regarding color match and anatomic form, no significant differences were found among the groups at each evaluation period. When materials were compared, Heliomolar did not show a significant difference among the evaluated periods for any criteria, remaining with the lowest scores. Significant differences were observed at 12 months for F2000 (marginal adaptation), and at 24 months for Dyract AP (marginal discoloration and secondary caries) and for F2000 (color match and marginal discoloration). CONCLUSIONS: It was concluded that Dyract AP and F2000 showed the best clinical performance over 24 month-evaluations for marginal discoloration and secondary caries, and color match and marginal adaptation, respectively. The use of the resin composite Heliomolar in Class I/II restorations in primary molars should be carefully considered.

Acrylic Resins↗

Microtensile bond strength to ground enamel by glass-ionomers, resin-modified glass-ionomers, and resin composites used as pit and fissure sealants.

OBJECTIVES: To measure the microtensile bond strength to ground enamel of different types of materials used as pit and fissure sealants in combination with different substrate conditioners. METHODS: From 40 sound extracted molars, eight groups of five teeth were randomly formed. The experimental groups were: (1) (C) 37% phosphoric acid/ClinPro Sealant (3M ESPE); (2) (G) 37% phosphoric acid/Guardian Seal (Kerr); (3) (E/TF) 37% phosphoric acid/Excite/Tetric Flow (Ivoclar-Vivadent) (4) (OS/UF) 37% phosphoric acid/One Step (Bisco)/UniFil Flow (GC); (5) (OS/AE) 37% phosphoric acid/One Step/AEliteflo (Bisco); (6) (UB/UF) UniFil Bond/UniFil Flow (GC); (7) (CC/FVII) GC Cavity Conditioner/Fuji VII (GC); (8) (CC/FII) GC Cavity Conditioner/Fuji II LC Improved (GC). On the buccal of each tooth, a 5mm high build-up was created by incrementally adding layers of the sealing material on the conditioned enamel. By serially cutting the built-up tooth, multiple beam-shaped specimens about 1mm x 1mm in cross section were obtained, and loaded in tensile (0.5 mm/min) until failure occurred. RESULTS: The bond strengths measured in MPa were: (C) 20.41+/-11.79; (G) 16.02+/-7.99; (E/TF) 24.06+/-9.67; OS/UF 15.63+/-9.00; (OS/AE) 9.31+/-6.05; (UB/UF) 4.96+/-3.46; (CC/FVII) 1.70+/-2.19; (CC/FII) 2.19+/-1.44. CONCLUSIONS: The conventional and the resin-modified glass ionomers measured bond strengths significantly lower than those of any resin-based materials. Failure frequently occurred cohesively within the cement. Flowable composites in combination with phosphoric acid and a total-etch adhesive performed similarly to resin-based materials specifically conceived for sealings, such as ClinPro Sealant and Guardian Seal. The bond achieved by resin composite when treating enamel with the self-etching primer used in this study (UniFil Bond) was significantly lower than that developed when the substrate was etched with 37% phosphoric acid.

Acrylic Resins↗

Stem cell responses in tooth regeneration.

Scientific advances in the creation of restorative biomaterials, in vitro cell culture technology, tissue grafting, tissue engineering, molecular biology, and the human genome project provide the basis for the introduction of new technologies into dentistry. This review is intended to facilitate the development of stem cell therapy for use with established therapeutic modalities to restore and regenerate oral tissues. Teeth have been shown to mineralize in response to injury for many decades, but only in recent years has the position of the stem cells been localized around blood vessels. The cells have been identified as myofibroblastoid pericytes. The ability to control the differentiation and proliferation of these cells is being examined to create stem cell therapies that can solve dental problems more effectively than current treatment regimes. Although the problems of introducing these technologies are substantial, the potential benefits to patients and the profession are equally promising - a cure for caries and diseases, a cure for oral cancer, correction of congenital defects, and the regeneration of teeth and tissues to restore oral functions. The purpose of this review is to describe how these new technologies can most usefully be employed in dentistry to enable clinicians to satisfy patient demand for a nondefective dentition.

Animals↗

Biological factors in dental caries enamel structure and the caries process in the dynamic process of demineralization and remineralization (part 2).

Dental caries is a complex disease process that afflicts a large proportion of the world's population, regardless of gender, age and ethnicity, although it does tend to affect more indivduals with a low socioeconomic status to a greater extent. The physicochemical properties of the mineral comprising the tooth surface and subsurface modulate the development, arrestment and remineralization of dental caries. Post-eruption maturation of enamel surfaces and exposed root surfaces is important in order for more susceptible mineral phases to be modified by incorporation of soluble fluoride from the plaque into dental hydroxyapatite. The chemical reactions that occur during acidic conditions when tooth mineral dissolves (critical pH) are determined by the supersaturation of calcium and phosphate within plaque and saliva, as well as if fluoride is present.

Apatites↗

Biological factors in dental caries: role of remineralization and fluoride in the dynamic process of demineralization and remineralization (part 3).

Dental caries is a complex disease process that afflicts a large proportion of the world, regardless of gender, age and ethnicity, although it does tend to affect more with a low socioeconomic status to a greater extent. Remineralization may be enhanced by providing low levels of calcium and phosphate, in conjunction with minimal amounts of fluoride. It is truly remarkable the difference that a very small amount of fluoride (<1 ppm) has upon demineralization and remineralization. This is because fluoride acts as a catalyst and influences reaction rates with dissolution and transformation of various calcium phosphate mineral phases within tooth structure and resident within plaque adjacent to tooth surfaces. The incorporation of minimal amounts of fluoride into HAP yields FHAP that resists demineralization to similar level as FAP. New and emerging methods have been and are in the process of being developed. These hold great promise for preventing and reversing caries, especially in the one-fifth of the population that accounts for two-thirds of the caries experience. Still, the mainstay in caries prevention and remineralization is frequent exposure to low levels of fluoride. This may be accomplished with fluoridated toothpastes, supplemented with fluoride mouthrinses, CPP-ACP containing chewing gum and application of fluoride varnishes. The role of systemic fluorides appears to be limited and primarily has a topical effect.

Apatites↗

In vitro cytotoxicity of five glass-ionomer cements.

To evaluate the cytotoxic effects of five glass-ionomer cements (GICs) on an odontoblast cell line (MDPC-23), disks of every material were prepared and divided into Group 1: Vitrebond, Group 2: Vitremer, Group 3: Fuji II LC, Group 4: Fuji IX GP, Group 5: Ketac-Molar, Group 6: Z-100 (positive control). In Group 7, phosphate-buffered saline solution (negative control) was applied on filter paper. After placing the samples in the bottom of wells, the cells (30,000cells/cm(2)) were plated and incubated for 72h. The cell number was counted, the cell morphology was assessed by scanning electron microscopy and the cell metabolism was evaluated using methyltetrazolium assay. The statistical analysis of Kruskal-Wallis was used to determine if the scores obtained for the cell metabolism and number of cells were different at the 95% confidence level. In groups 1, 2, 3, 4, 5, and 6 the materials decreased the cell number by 74.5%, 75.5%, 45.5%, 29.5%, 32.5%, and 88.5%, respectively. In groups 1, 2, 3, 4, and 5, the experimental GICs reduced the cell metabolism by 79%, 84%, 54%, 40%, and 42.5%, respectively. Despite the fact that all experimental materials were cytotoxic to the MDPC-23 cells, the GICs were the least cytotoxic. On the other hand, the RMGICs caused the highest cytophatic effects.

Animals↗

Sorption and solubility of resin-based restorative dental materials.

OBJECTIVES: To measure the water sorption and solubility of different resin-based restorative dental materials. METHODS: Eight commercial restorative materials were selected: two resin composites (Z100 and Prodigy), four polyacid-modified resin composites (Compoglass, Compoglass F, Dyract and Dyract AP), and two light-cured glass ionomers (Vitremer and Fuji II LC). Five disc specimens were prepared of each material, following the manufacturer's instructions, and were grounded wet with silicon carbide paper. Water sorption and solubility of the different materials were calculated by means of weighting the samples before and after water immersion and desiccation. Data were analyzed by one-way ANOVA and Student-Newman-Keuls tests (P<0.05). RESULTS: Compoglass and Compoglass F showed the lowest values of water sorption and solubility, while Vitremer and Fuji II LC displayed the highest values. Solubility values of Prodigy, Z100, Dyract and Dyract AP did not show significant differences among them, while their water sorption values attained some differences and were lower for Prodigy followed by Dyract and Z100. CONCLUSIONS: The attained water sorption and solubility values are mainly influenced by the generic type of material and variations occurring between materials of the same type may result from differences in resin matrix compositions.

Absorption↗

Biological factors in dental caries: role of saliva and dental plaque in the dynamic process of demineralization and remineralization (part 1).

Dental caries is a complex disease process that afflicts a large proportion of the world's population, regardless of gender, age and ethnicity, although it does tend to affect more indivduals with a low socioeconomic status to a greater extent. The process of dental caries is dependent upon biological factors that are present within the saliva and dental plaque. There are many different agents within saliva and plaque that serve to protect the tooth surface against caries development. Salivary flow rate, buffering capacity, antimicrobial activity, microorganism aggregation and clearance from the oral cavity, immune surveillance, and calcium phosphate binding proteins all interact to inhibit or reverse demineralization of exposed tooth surfaces. Cariogenic bacteria levels within the saliva and plaque determine whether caries will occur or not, and the concentration in saliva and plaque are intimately related to the type of carbohydrate ingestion and the frequency of ingestion, as well as the oral hygiene practiced by the individual.

Dental Caries↗

Fluoride-releasing restorative materials and secondary caries.

Secondary caries is responsible for 60 percent of all replacement restorations in the typical dental practice. Risk factors for secondary caries are similar to those for primary caries development. Unfortunately, it is not possible to accurately predict which patients are at risk for restoration failure. During the past several decades, fluoride-releasing dental materials have become a part of the dentist's armamentarium. Considerable fluoride is released during the setting reaction and for periods up to eight years following restoration placement. This released fluoride is readily taken up by the cavosurface tooth structure, as well as the enamel and root surfaces adjacent to the restoration. Resistance against caries along the cavosurface and the adjacent smooth surface has been shown in both in vitro and in vivo studies. Fluoride-releasing dental materials provide for improved resistance against primary and secondary caries in coronal and root surfaces. Plaque and salivary fluoride levels are elevated to a level that facilitates remineralization. In addition, the fluoride released to dental plaque adversely affects the growth of lactobacilli and mutans streptococci by interference with bacterial enzyme systems. Fluoride recharging of these dental materials is readily achieved with fluoridated toothpastes, fluoride mouthrinses, and other sources of topical fluoride. This allows fluoride-releasing dental materials to act as intraoral fluoride reservoirs. The improvement in the properties of dental materials with the ability to release fluoride has improved dramatically in the past decade, and it is anticipated that in the near future the vast majority of restorative procedures will employ fluoride-releasing dental materials as bonding agents, cavity liners, luting agents, adhesives for orthodontic brackets, and definitive restoratives.

Adolescent↗

Fluoride-releasing restorative materials and secondary caries.

Secondary caries are responsible for 60% of all replacement restorations in the typical dental practice. Risk factors for secondary caries are similar to those for primary caries development. Unfortunately, it is not possible to predict accurately which patients are at risk for restoration failure. Fluoride-releasing dental materials provide for improved resistance against primary and secondary caries in coronal and root surfaces and have become a part of the dentist's armamentarium. This article discusses the improvement in the properties of dental materials with the ability to release fluoride. It is anticipated that in the near future, the vast majority of restorative procedures will employ fluoride-releasing dental materials as bonding agents, cavity liners, luting agents, adhesives for orthodontic brackets, and as definitive restoratives.

Dental Caries↗

Tooth whitening in children.

Although there are several case reports of vital tooth bleaching in children, there is limited clinical trial evidence of the safety or efficacy of this practice. Accordingly, a new clinical trial was conducted to evaluate the effects of 2 different bleaching systems, a 6.5% hydrogen peroxide strip system and a 10% carbamide peroxide tray system, in a population of preteens and teens. A total of 106 volunteers, aged 11 to 18 years, took part in this 8-week study. Patients were randomized by a ratio of 2:1 to the strip or tray groups, with each group treating the maxillary arch first and then the mandibular arch for 4 consecutive weeks each. Individuals assigned to the strip group used the system twice daily for 30 minutes (a total of 56 contact hours over the 8-week study). Those assigned to the tray group used that system overnight (approximately 448 contact hours). Digital images were obtained at baseline and after every 2-week treatment period. Average tooth color was determined in L*, a*, b* color space, where L* indicated lightness, a* indicated red-green, and b* indicated yellow-blue. Both systems significantly whitened teeth (P < 0.0001). While there were no significant differences between groups with respect to the primary whitening response (delta b*) on the maxillary teeth, 4 weeks of overnight treatment with the 10% carbamide peroxide tray (approximately 224 contact hours) yielded statistically significant whitening (P < 0.05) on the mandibular teeth compared with the 6.5% hydrogen peroxide strip used for 28 hours. Both tooth-whitening systems had similar sensitivity/irritation reported after instructed use. This research demonstrates that tooth whitening in teens may be safely accomplished using either the short-contact-time hydrogen peroxide bleaching strips or the overnight carbamide peroxide tray systems tested in this study.

Adolescent↗

Effect of curing time and light curing systems on the surface hardness of compomers.

This study compared the Vickers hardness of the top and bottom surfaces of two compomers (Compoglass F and Dyract AP) polymerized for 20 and 40 seconds with two different light curing systems. Five samples for each group were prepared using Teflon molds (9x2 mm) and were light-cured either with a conventional halogen lamp (Optilux 501) or LED light (LEDemetron I) for 20 or 40 seconds. After curing, all the samples were stored in distilled water for 24 hours at 37 degrees C. The Vickers hardness measurements were obtained from the top and bottom surfaces of each sample. ANOVA, Scheffé and t-test were used to evaluate the statistical significance of the results. For the top and bottom surfaces, the light curing systems and curing times tested showed no statistical difference, except for Optilux 501, which used 20 seconds for both compomers (p<0.05). There was no significant difference in the microhardness of both surfaces of Compoglass F and Dyract AP cured for either 20 or 40 seconds using LEDemetron I. With Optilux 501, the microhardness of samples cured for 40 seconds was significantly higher than 20 seconds (p<0.05).

Compomers↗

Compomer as a pit and fissure sealant: effectiveness and retention after 24 months.

PURPOSE: The aim of this study was to evaluate the effectiveness and retention of occlusal sealing using FluroShield or Compoglass. METHODS: The sample consisted of 57 children aged 7 to 9 years who had 4 sound, fully erupted, first permanent molars (total=228 teeth). Both materials were applied on contralateral teeth in a split-mouth design in 2 groups: (1) FluroShield--left upper molar and right lower molar; (2) Compoglass--right upper molar and left lower molar. The materials were applied under cotton roll isolation by the same operator according to the manufacturers' instructions. The evaluations were carried out at 6, 12, and 24 months. The data were subjected to the G2 (likelihood ratio chi-square test; P<.05). RESULTS: At the 6-month evaluation, Compoglass showed 60% total retention, 23% partial retention, and 17% total loss. FluroShield showed 53% total retention, 31% partial retention, and 16% total loss. At the 12-month recall, Compoglass and FluroShield, respectively, showed 39% and 43% total retention, 38% and 33% partial retention, and 24% and 25% total loss. At the 24-month evaluation, there was a reduction of 56% of the initial sample numbers (32/57), with 22% and 20% having total retention, 52% and 48% partial retention, and 26% and 32% total loss, respectively, for Compoglass and FluroShield. There was no significant statistical difference between the retention of both materials studied. There was no new caries formation during the evaluation period. CONCLUSION: It could be concluded that both materials effectively prevented caries in occlusal surfaces during the follow-up period, although both showed a low retention rates.

Bisphenol A-Glycidyl Methacrylate↗