The study evaluated the influence of curing methods (continuous light, soft-start, pulse delay) and composite volumes (12.6 mm3, 24.5 mm3) on the marginal and internal adaptation of composite restorations. Sixty bovine teeth were prepared with cavities of different volumes and restored with composite using different curing methods. Marginal and internal gaps were measured. The results showed that higher composite volumes led to greater gap formation, and modulated curing methods reduced gap formation, particularly for higher volume restorations and internal adaptation of lower volume restorations. Therefore, composite volume and curing method can impact adaptation, and modulated curing may help reduce gaps.
This study evaluated three composite resins (Z100, Clearfil Ray-Posterior, and Prisma TPH) used to restore 120 posterior teeth over 24 months. Clinical evaluations were performed every 6 months using Ryge criteria and stone casts, while direct evaluations assessed color match, margins, anatomy, etc. Results found that all materials were suitable for posterior restorations. Some Z100 and Prisma TPH restorations showed marginal crevices. Clearfil Ray-Posterior alone showed slight surface roughness. Direct and indirect evaluation results differed for Z100 and Prisma TPH, attributed to method sensitivity.
This study evaluated the influence of LED curing units and selective enamel etching on the dentin bond strength of self-etch adhesives in class I composite restorations. Two self-etch adhesives were bonded to dentin with or without prior enamel etching and cured with different LED curing lights. The dentin bond strength was measured and the failure modes analyzed. Selective enamel etching decreased the bond strength of one adhesive but not the other. A polywave LED provided stronger bonding than single-peak LEDs for one of the adhesives tested.
This study evaluated the degree of conversion (DC) of nine one-bottle adhesive systems when photo-activated under different conditions of solvent volatilization. The adhesives were tested with five evaporation methods: without solvent volatilization, left undisturbed for 10 or 60 seconds, or air-dried for 10 or 60 seconds before curing. Fourier transform infrared spectroscopy results showed that the DC of most adhesives increased with extended (60 second) passive or active air-drying before curing. However, the DC of two adhesives was not affected by the evaporation conditions. In general, allowing more time for solvent evaporation enhanced the DC of the one-bottle simplified adhesive systems tested
This study evaluated the effect of using a warm versus cold air stream for solvent evaporation on the properties of two etch-and-rinse adhesive systems. Microtensile bond strength and nanoleakage patterns were compared between the two drying methods. Degree of conversion and solvent evaporation rates were also analyzed. The results showed that using a warm air stream improved bond strength and reduced nanoleakage, without affecting degree of conversion. This suggests that a warm air dry may help form a stronger polymer network within the hybrid layer.
This study compared the clinical performance of a polyacid modified resin composite (Dyract eXtra) and a nanocomposite (Filtek Supreme) when used with an antibacterial adhesive system (Clearfil Protect Bond) to restore noncarious cervical lesions over 2 years. 100 restorations were placed - 50 of each material - and evaluated at baseline and 6, 12, and 24 months using criteria like color match, marginal adaptation, retention, etc. Both materials showed acceptable clinical performance, though Filtek Supreme had a significantly better retention rate (100% vs 96% for Dyract eXtra). Some Dyract eXtra restorations were lost or fractured. Overall both materials can be suitable options for restoring
This study investigated the effect of material chemistry and prolonged setting time on the permanent deformation of light-body elastomeric impression materials after stretching. Specimens of 6 impression materials were either stored for the manufacturer's recommended setting time or 5 minutes before being stretched by 80%. Polyether materials showed significantly higher permanent deformation than vinyl polysiloxane materials. Extending the setting time only improved elastic recovery for polyether materials, not vinyl polysiloxane materials. Increasing the setting time may be necessary for polyether impression materials to improve elastic recovery from deformation.
This study evaluated the degree of conversion (DC) and plasticization of a pit and fissure sealant (Fluroshield) and a flowable composite (Permaflo) when cured for either 20 or 60 seconds. The key findings were:
1) Permaflo had a higher DC than Fluroshield at both curing times. Extended curing (60 seconds) increased the DC of Permaflo but not Fluroshield.
2) Fluroshield showed higher plasticization (hardness decrease after ethanol storage) than Permaflo. Extended curing did not decrease plasticization for either material.
3) There was a low negative correlation between DC and plasticization, suggesting DC
This study evaluated the influence of LED curing light type and selective enamel etching on the dentin microtensile bond strength (μTBS) of two self-etch adhesives (Clearfil SE and Clearfil S3) in class I composite restorations. For Clearfil S3, selective enamel etching resulted in lower dentin μTBS values compared to non-etched specimens. However, dentin μTBS of Clearfil SE was not affected by enamel etching. When curing the adhesives, the polywave LED yielded higher dentin μTBS for Clearfil SE than the single-peak LEDs. Enamel etching and LED type influenced dentin bonding of the self-etch ad
This study evaluated three composite resins (Z100, Clearfil Ray-Posterior, and Prisma TPH) used to restore 120 posterior teeth over 24 months. Clinical evaluations were performed every 6 months using Ryge criteria and stone casts, while direct evaluations assessed color match, margins, anatomy, etc. Results found that all materials were suitable for posterior restorations. Some Z100 and Prisma TPH restorations showed marginal crevices. Clearfil Ray-Posterior alone showed slight surface roughness. Direct and indirect evaluation results differed for Z100 and Prisma TPH, attributed to method sensitivity.
This study evaluated the influence of LED curing units and selective enamel etching on the dentin bond strength of self-etch adhesives in class I composite restorations. Two self-etch adhesives were bonded to dentin with or without prior enamel etching and cured with different LED curing lights. The dentin bond strength was measured and the failure modes analyzed. Selective enamel etching decreased the bond strength of one adhesive but not the other. A polywave LED provided stronger bonding than single-peak LEDs for one of the adhesives tested.
This study evaluated the degree of conversion (DC) of nine one-bottle adhesive systems when photo-activated under different conditions of solvent volatilization. The adhesives were tested with five evaporation methods: without solvent volatilization, left undisturbed for 10 or 60 seconds, or air-dried for 10 or 60 seconds before curing. Fourier transform infrared spectroscopy results showed that the DC of most adhesives increased with extended (60 second) passive or active air-drying before curing. However, the DC of two adhesives was not affected by the evaporation conditions. In general, allowing more time for solvent evaporation enhanced the DC of the one-bottle simplified adhesive systems tested
This study evaluated the effect of using a warm versus cold air stream for solvent evaporation on the properties of two etch-and-rinse adhesive systems. Microtensile bond strength and nanoleakage patterns were compared between the two drying methods. Degree of conversion and solvent evaporation rates were also analyzed. The results showed that using a warm air stream improved bond strength and reduced nanoleakage, without affecting degree of conversion. This suggests that a warm air dry may help form a stronger polymer network within the hybrid layer.
This study compared the clinical performance of a polyacid modified resin composite (Dyract eXtra) and a nanocomposite (Filtek Supreme) when used with an antibacterial adhesive system (Clearfil Protect Bond) to restore noncarious cervical lesions over 2 years. 100 restorations were placed - 50 of each material - and evaluated at baseline and 6, 12, and 24 months using criteria like color match, marginal adaptation, retention, etc. Both materials showed acceptable clinical performance, though Filtek Supreme had a significantly better retention rate (100% vs 96% for Dyract eXtra). Some Dyract eXtra restorations were lost or fractured. Overall both materials can be suitable options for restoring
This study investigated the effect of material chemistry and prolonged setting time on the permanent deformation of light-body elastomeric impression materials after stretching. Specimens of 6 impression materials were either stored for the manufacturer's recommended setting time or 5 minutes before being stretched by 80%. Polyether materials showed significantly higher permanent deformation than vinyl polysiloxane materials. Extending the setting time only improved elastic recovery for polyether materials, not vinyl polysiloxane materials. Increasing the setting time may be necessary for polyether impression materials to improve elastic recovery from deformation.
This study evaluated the degree of conversion (DC) and plasticization of a pit and fissure sealant (Fluroshield) and a flowable composite (Permaflo) when cured for either 20 or 60 seconds. The key findings were:
1) Permaflo had a higher DC than Fluroshield at both curing times. Extended curing (60 seconds) increased the DC of Permaflo but not Fluroshield.
2) Fluroshield showed higher plasticization (hardness decrease after ethanol storage) than Permaflo. Extended curing did not decrease plasticization for either material.
3) There was a low negative correlation between DC and plasticization, suggesting DC
This study evaluated the influence of LED curing light type and selective enamel etching on the dentin microtensile bond strength (μTBS) of two self-etch adhesives (Clearfil SE and Clearfil S3) in class I composite restorations. For Clearfil S3, selective enamel etching resulted in lower dentin μTBS values compared to non-etched specimens. However, dentin μTBS of Clearfil SE was not affected by enamel etching. When curing the adhesives, the polywave LED yielded higher dentin μTBS for Clearfil SE than the single-peak LEDs. Enamel etching and LED type influenced dentin bonding of the self-etch ad
This document summarizes a study evaluating the use of carbon fiber post systems for restoring teeth defects in children. 106 children with anterior tooth defects from trauma or decay were restored with carbon fiber posts, resin cores, and jacket crowns and observed for 3-5 years on average. The restorations were deemed successful in 121 cases (96.2%), with only 4 crowns lost. The study concluded that carbon fiber post systems can satisfactorily restore anterior teeth in children, with good esthetic and functional outcomes and ease of use for dentists.
The document summarizes a clinical study that compared the performance of a two-step self-etching adhesive system (Clearfil Protect Bond) and a one-step self-etching adhesive system (Xeno III) over one year. 163 restorations were placed in noncarious cervical lesions in 35 patients using the two adhesive systems. The restorations were evaluated at baseline and 3, 6, 9, and 12 months using criteria such as color matching, marginal adaptation, retention, etc. At one year, the retention rate was 100% for the two-step system and 96% for the one-step system. Both systems showed excellent performance during the one-year clinical trial, though the two-step system
This document summarizes research into the effects of processing conditions on the structure and properties of poly(lactic acid) (PLA) nanohydroxyapatite (nHA) composites. Compounding PLA and nHA under nitrogen gas reduced the molecular weight and flexural strength of the composites due to the presence of water. Adding nHA helped offset these effects by interacting with residual water. Further drying the nitrogen gas and separately drying the nHA before compounding mostly recovered the flexural strength and molecular weight by removing water. Controlling the moisture content during processing is important to reduce degradation of the composites after implantation.
An Inverse Approach for the Determination of Viscous Damping Model of Fibre R...Subhajit Mondal
Investigations have been carried out both numerically and experimentally to settle with a practically feasible set
of proportional viscous damping parameters for the accurate prediction of responses of fibre reinforced plastic
beams over a chosen frequency range of interest. The methodology needs accurate experimental modal testing,
an adequately converged finite element model, a rational basis for correct correlations between these two models,
and finally, updating of the finite element model by estimating a pair of global viscous damping coefficients using
a gradient-based inverse sensitivity algorithm. The present approach emphasises that the successful estimate of
the damping matrix is related to a-priori estimation of material properties, as well. The responses are somewhat
accurately predicted using these updated damping parameters over a large frequency range. In the case of plates,
determination of in-plane stiffness parameters becomes easier, whereas for beam specimens, transverse material
properties play a comparatively greater role and need to be determined. Moreover, for damping matrix parameter
estimation, frequency response functions need to be used instead of frequencies and mode shapes. The proposed
method of damping matrix identification is able to reproduce frequency response functions accurately even outside
the frequency ranges used for identification.
Here is a 3 sentence summary of the key points from the document:
SUMMARY: This study aimed to evaluate the effect of selective enamel etching and different light-emitting diode (LED) curing units on gap formation of two self-etch adhesive systems in Class I composite restorations after thermomechanical aging. One hundred ninety-two human molars received Class I cavities that were restored with either Clearfil SE Bond or Clearfil Tri-S Bond and a microhybrid composite. The restorations were evaluated using scanning electron microscopy to analyze the influence of prior enamel etching and three LED curing lights on marginal adaptation before and after thermomechanical aging.
This case study describes the treatment of a patient with severe recession and compromised esthetics of the upper front teeth. A multidisciplinary treatment plan was developed involving periodontal plastic surgery using an acellular dermal graft for root coverage, followed by prosthetic rehabilitation with crowns. The surgery involved grafting and tissue shaping to improve the gingival contours. After healing, crowns were placed on teeth #6-10 to improve esthetics and function. The final result achieved the patient's goal of enhanced appearance with minimal time and cost.
This study evaluated the clinical performance of a self-etching adhesive system (Clearfil SE Bond) and a one-bottle adhesive system (Prime&Bond NT) in non-carious Class V restorations over 2 years. 98 restorations were placed in 32 patients using the two adhesive systems. At 2 years, the retention rates were 93% for Clearfil SE Bond and 91% for Prime&Bond NT, showing very good clinical performance for both systems with no statistically significant differences in failure rates. A few restorations showed slight marginal discoloration or adaptation issues, but no restorations exhibited postoperative sensitivity, recurrent caries or changes in anatomical form.
This study evaluated nanoleakage at the interface between dental enamel, leucite-reinforced ceramic, and four different resin luting systems. Bovine teeth were divided into four groups based on the luting procedure used: Excite adhesive with Variolink II cement, Clearfil SE Bond with Panavia F cement, Scotchbond Multi-Purpose Plus with RelyX ARC cement, or Single Bond 2 with Filtek Z350 Flow composite. Specimens were immersed in silver nitrate and examined under SEM. The Single Bond 2/Filtek Z350 Flow group showed no nanoleakage at the enamel interface. The Excite/Variolink II group had the highest nanoleakage
This article describes the long-term treatment of a case of molar incisor hypomineralization (MIH) involving both anterior and posterior teeth. Initial treatment included calcium-phosphate supplementation, which SEM images showed improved the enamel morphology. Later treatments included orthodontics, bleaching of anterior teeth, and restorative work. An 8-year follow-up found that calcium-phosphate supplementation, bleaching, and restorations effectively addressed the esthetic and functional issues caused by the MIH while minimizing intervention.
The document provides a list of verbs paired with nouns or adjectives. Some key pairings include state and statement, agree and agreement, reduce and reduction, educate and education, develop and development, compete and competition, consume and consumption. The document also categorizes verbs based on their pairing with nouns referring to things, people, or activities. Additionally, it contrasts different adjectives like modern and ancient, safe and dangerous, few and more.
This study evaluated the effect of different curing light sources and chemical catalysts on the degree of conversion of two dual-cured resin luting cements, RelyX ARC and Panavia F. Specimens were light cured using an argon ion laser, LED, or halogen light through a composite disk. The degree of conversion was measured using FTIR. For RelyX ARC, satisfactory curing was achieved with any light source with or without chemical catalyst. For Panavia F, the highest degree of conversion was achieved when used with ED Primer and cured with halogen light. The type of curing light and use of chemical catalyst influenced the degree of conversion of the resin luting cements
This study examines senior fi nance
executives’ cost-management
achievements in the course of the
downturn and explores the role that
continued cost discipline will play in
midsize companies’ growth efforts in
the months and years to come.
Small and midsize companies are experiencing some recovery from the economic downturn but expect only modest improvement in business prospects over the next year. Most companies are pursuing relatively low-risk growth strategies like increasing market penetration of existing products rather than riskier strategies. While companies previously focused on bottom-line profitability, most now aim for sustained profitable growth balancing top and bottom lines. Finance executives believe maintaining a lean cost structure will provide an important competitive advantage as the recovery continues. Companies have improved at managing costs over the past two years but see opportunities to further consolidate spending and help employees adapt spending behaviors.
This study investigated the impact of extended curing time on the polymerization depth of fluoride-containing pit and fissure sealant materials. Specifically, it evaluated the Knoop hardness number (KHN) of the top and bottom surfaces of a conventional pit and fissure sealant and a flowable composite cured for the manufacturers' recommended time of 20 seconds as well as an extended time of 60 seconds. The flowable composite exhibited higher KHN values than the pit and fissure sealant under all curing conditions. An extended curing time of 60 seconds increased the KHN of the bottom surface and bottom/top hardness ratio of the composite but did not significantly impact the sealant. The flowable composite demonstrated
This document summarizes a study that evaluated the surface roughness and color stability of two resin composites (Z250 and 4 Seasons) after polishing with two systems (Sof-Lex and Jiffy). Specimens were polished and their surface roughness and color changes after staining in coffee solution were measured. The results showed that 4 Seasons composite polished with Jiffy had the lowest surface roughness and color variation. Z250 presented higher roughness values compared to 4 Seasons. The study concluded that polishing affected surface roughness and staining susceptibility of the composites.
Este documento presenta los conceptos y pasos fundamentales de la Medicina Basada en Evidencias (MBE). En primer lugar, define la MBE como la combinación de la evaluación clínica del paciente y la mejor evidencia disponible para tomar decisiones sobre su atención. Luego, describe los pasos de la MBE, que comienzan con una pregunta clínica derivada del caso del paciente y terminan integrando la evidencia encontrada con la situación particular del paciente. Por último, enfatiza que la MBE siempre comienza y termina con el paciente.
Most of the student respondents were 13 years old females. In terms of academic performance in English, most respondents had average performance. The study found that factors like sex, age, number of siblings, parents' employment status, education attainment and socioeconomic status had no significant influence on academic performance in English. It was concluded that selected variables did not influence performance, and most students had average intellectual capacity in English. Recommendations included teachers motivating students, parents assisting with schoolwork, and students changing study habits.
This study evaluated the bond durability of dentin restorations bonded with light-cured or dual-cured etch-and-rinse adhesive systems, finding that dual-cured adhesive systems produced higher immediate bond strength and durability compared to light-cured systems, and that a three-step adhesive system resulted in the highest bond values while an acetone-based two-step system produced the lowest.
This study evaluated the effect of dentin pre-treatment with casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) paste on the push-out bond strength of dimethacrylate-based and silorane-based restorative systems. Bovine teeth were treated with or without CPP-ACP paste prior to application of Clearfil SE Bond/Filtek Z250, Adper SE Plus/Filtek Z250, or Filtek P90 adhesive system/Filtek P90 composite. Dentin pre-treatment did not affect bond strength for Clearfil SE Bond/Filtek Z250 or Filtek P90 adhesive system/Filtek P90. For Adper SE
This study assessed the effect of 2% chlorhexidine digluconate (CHX) pretreatment on the immediate and six-month microshear bond strength (μSBS) of an etch-and-rinse adhesive to sound and eroded dentin. Bovine teeth were subjected to either a control treatment or erosive challenge to create sound and eroded dentin substrates. Specimens received adhesive with or without prior CHX application. μSBS was measured initially and after six months. CHX pretreatment minimized but did not prevent the reduction in μSBS over time, especially for eroded dentin. While CHX helped maintain higher bond strengths after aging, the effectiveness of bonding to
1. Incremental layering techniques are recommended to reduce polymerization shrinkage stress by decreasing the C-factor at each stage of restoration. This allows for stress relief between increments.
2. Flowable composites with lower elastic moduli have been used as intermediate layers to absorb shrinkage stress from subsequent higher modulus resin composite layers through an "elastic cavity wall" effect. However, flowable composites do not significantly reduce stress.
3. Alternative curing methods like soft-start and pulse-delay curing may slightly reduce shrinkage stress by allowing more time for resin flow before full conversion. However, opportunities for stress relief are still limited and conversion levels may be lower.
This study evaluated the Knoop hardness of resin composite restorations photoactivated by different methods when different mold materials were used. Resin composite samples were cured using high-intensity continuous, low-intensity continuous, soft-start, or pulse-delay methods and placed in either a bovine tooth or metal mold. Knoop hardness was measured on the top and bottom surfaces. On the top surface, hardness did not differ between curing methods but was higher for the metal mold. On the bottom, high-intensity continuous curing produced higher hardness than low-intensity continuous, and hardness was influenced by the mold material used. The results indicate that photoactivation method and mold can impact hardness values of resin composite restorations.
This document summarizes a study evaluating the use of carbon fiber post systems for restoring teeth defects in children. 106 children with anterior tooth defects from trauma or decay were restored with carbon fiber posts, resin cores, and jacket crowns and observed for 3-5 years on average. The restorations were deemed successful in 121 cases (96.2%), with only 4 crowns lost. The study concluded that carbon fiber post systems can satisfactorily restore anterior teeth in children, with good esthetic and functional outcomes and ease of use for dentists.
The document summarizes a clinical study that compared the performance of a two-step self-etching adhesive system (Clearfil Protect Bond) and a one-step self-etching adhesive system (Xeno III) over one year. 163 restorations were placed in noncarious cervical lesions in 35 patients using the two adhesive systems. The restorations were evaluated at baseline and 3, 6, 9, and 12 months using criteria such as color matching, marginal adaptation, retention, etc. At one year, the retention rate was 100% for the two-step system and 96% for the one-step system. Both systems showed excellent performance during the one-year clinical trial, though the two-step system
This document summarizes research into the effects of processing conditions on the structure and properties of poly(lactic acid) (PLA) nanohydroxyapatite (nHA) composites. Compounding PLA and nHA under nitrogen gas reduced the molecular weight and flexural strength of the composites due to the presence of water. Adding nHA helped offset these effects by interacting with residual water. Further drying the nitrogen gas and separately drying the nHA before compounding mostly recovered the flexural strength and molecular weight by removing water. Controlling the moisture content during processing is important to reduce degradation of the composites after implantation.
An Inverse Approach for the Determination of Viscous Damping Model of Fibre R...Subhajit Mondal
Investigations have been carried out both numerically and experimentally to settle with a practically feasible set
of proportional viscous damping parameters for the accurate prediction of responses of fibre reinforced plastic
beams over a chosen frequency range of interest. The methodology needs accurate experimental modal testing,
an adequately converged finite element model, a rational basis for correct correlations between these two models,
and finally, updating of the finite element model by estimating a pair of global viscous damping coefficients using
a gradient-based inverse sensitivity algorithm. The present approach emphasises that the successful estimate of
the damping matrix is related to a-priori estimation of material properties, as well. The responses are somewhat
accurately predicted using these updated damping parameters over a large frequency range. In the case of plates,
determination of in-plane stiffness parameters becomes easier, whereas for beam specimens, transverse material
properties play a comparatively greater role and need to be determined. Moreover, for damping matrix parameter
estimation, frequency response functions need to be used instead of frequencies and mode shapes. The proposed
method of damping matrix identification is able to reproduce frequency response functions accurately even outside
the frequency ranges used for identification.
Here is a 3 sentence summary of the key points from the document:
SUMMARY: This study aimed to evaluate the effect of selective enamel etching and different light-emitting diode (LED) curing units on gap formation of two self-etch adhesive systems in Class I composite restorations after thermomechanical aging. One hundred ninety-two human molars received Class I cavities that were restored with either Clearfil SE Bond or Clearfil Tri-S Bond and a microhybrid composite. The restorations were evaluated using scanning electron microscopy to analyze the influence of prior enamel etching and three LED curing lights on marginal adaptation before and after thermomechanical aging.
This case study describes the treatment of a patient with severe recession and compromised esthetics of the upper front teeth. A multidisciplinary treatment plan was developed involving periodontal plastic surgery using an acellular dermal graft for root coverage, followed by prosthetic rehabilitation with crowns. The surgery involved grafting and tissue shaping to improve the gingival contours. After healing, crowns were placed on teeth #6-10 to improve esthetics and function. The final result achieved the patient's goal of enhanced appearance with minimal time and cost.
This study evaluated the clinical performance of a self-etching adhesive system (Clearfil SE Bond) and a one-bottle adhesive system (Prime&Bond NT) in non-carious Class V restorations over 2 years. 98 restorations were placed in 32 patients using the two adhesive systems. At 2 years, the retention rates were 93% for Clearfil SE Bond and 91% for Prime&Bond NT, showing very good clinical performance for both systems with no statistically significant differences in failure rates. A few restorations showed slight marginal discoloration or adaptation issues, but no restorations exhibited postoperative sensitivity, recurrent caries or changes in anatomical form.
This study evaluated nanoleakage at the interface between dental enamel, leucite-reinforced ceramic, and four different resin luting systems. Bovine teeth were divided into four groups based on the luting procedure used: Excite adhesive with Variolink II cement, Clearfil SE Bond with Panavia F cement, Scotchbond Multi-Purpose Plus with RelyX ARC cement, or Single Bond 2 with Filtek Z350 Flow composite. Specimens were immersed in silver nitrate and examined under SEM. The Single Bond 2/Filtek Z350 Flow group showed no nanoleakage at the enamel interface. The Excite/Variolink II group had the highest nanoleakage
This article describes the long-term treatment of a case of molar incisor hypomineralization (MIH) involving both anterior and posterior teeth. Initial treatment included calcium-phosphate supplementation, which SEM images showed improved the enamel morphology. Later treatments included orthodontics, bleaching of anterior teeth, and restorative work. An 8-year follow-up found that calcium-phosphate supplementation, bleaching, and restorations effectively addressed the esthetic and functional issues caused by the MIH while minimizing intervention.
The document provides a list of verbs paired with nouns or adjectives. Some key pairings include state and statement, agree and agreement, reduce and reduction, educate and education, develop and development, compete and competition, consume and consumption. The document also categorizes verbs based on their pairing with nouns referring to things, people, or activities. Additionally, it contrasts different adjectives like modern and ancient, safe and dangerous, few and more.
This study evaluated the effect of different curing light sources and chemical catalysts on the degree of conversion of two dual-cured resin luting cements, RelyX ARC and Panavia F. Specimens were light cured using an argon ion laser, LED, or halogen light through a composite disk. The degree of conversion was measured using FTIR. For RelyX ARC, satisfactory curing was achieved with any light source with or without chemical catalyst. For Panavia F, the highest degree of conversion was achieved when used with ED Primer and cured with halogen light. The type of curing light and use of chemical catalyst influenced the degree of conversion of the resin luting cements
This study examines senior fi nance
executives’ cost-management
achievements in the course of the
downturn and explores the role that
continued cost discipline will play in
midsize companies’ growth efforts in
the months and years to come.
Small and midsize companies are experiencing some recovery from the economic downturn but expect only modest improvement in business prospects over the next year. Most companies are pursuing relatively low-risk growth strategies like increasing market penetration of existing products rather than riskier strategies. While companies previously focused on bottom-line profitability, most now aim for sustained profitable growth balancing top and bottom lines. Finance executives believe maintaining a lean cost structure will provide an important competitive advantage as the recovery continues. Companies have improved at managing costs over the past two years but see opportunities to further consolidate spending and help employees adapt spending behaviors.
This study investigated the impact of extended curing time on the polymerization depth of fluoride-containing pit and fissure sealant materials. Specifically, it evaluated the Knoop hardness number (KHN) of the top and bottom surfaces of a conventional pit and fissure sealant and a flowable composite cured for the manufacturers' recommended time of 20 seconds as well as an extended time of 60 seconds. The flowable composite exhibited higher KHN values than the pit and fissure sealant under all curing conditions. An extended curing time of 60 seconds increased the KHN of the bottom surface and bottom/top hardness ratio of the composite but did not significantly impact the sealant. The flowable composite demonstrated
This document summarizes a study that evaluated the surface roughness and color stability of two resin composites (Z250 and 4 Seasons) after polishing with two systems (Sof-Lex and Jiffy). Specimens were polished and their surface roughness and color changes after staining in coffee solution were measured. The results showed that 4 Seasons composite polished with Jiffy had the lowest surface roughness and color variation. Z250 presented higher roughness values compared to 4 Seasons. The study concluded that polishing affected surface roughness and staining susceptibility of the composites.
Este documento presenta los conceptos y pasos fundamentales de la Medicina Basada en Evidencias (MBE). En primer lugar, define la MBE como la combinación de la evaluación clínica del paciente y la mejor evidencia disponible para tomar decisiones sobre su atención. Luego, describe los pasos de la MBE, que comienzan con una pregunta clínica derivada del caso del paciente y terminan integrando la evidencia encontrada con la situación particular del paciente. Por último, enfatiza que la MBE siempre comienza y termina con el paciente.
Most of the student respondents were 13 years old females. In terms of academic performance in English, most respondents had average performance. The study found that factors like sex, age, number of siblings, parents' employment status, education attainment and socioeconomic status had no significant influence on academic performance in English. It was concluded that selected variables did not influence performance, and most students had average intellectual capacity in English. Recommendations included teachers motivating students, parents assisting with schoolwork, and students changing study habits.
This study evaluated the bond durability of dentin restorations bonded with light-cured or dual-cured etch-and-rinse adhesive systems, finding that dual-cured adhesive systems produced higher immediate bond strength and durability compared to light-cured systems, and that a three-step adhesive system resulted in the highest bond values while an acetone-based two-step system produced the lowest.
This study evaluated the effect of dentin pre-treatment with casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) paste on the push-out bond strength of dimethacrylate-based and silorane-based restorative systems. Bovine teeth were treated with or without CPP-ACP paste prior to application of Clearfil SE Bond/Filtek Z250, Adper SE Plus/Filtek Z250, or Filtek P90 adhesive system/Filtek P90 composite. Dentin pre-treatment did not affect bond strength for Clearfil SE Bond/Filtek Z250 or Filtek P90 adhesive system/Filtek P90. For Adper SE
This study assessed the effect of 2% chlorhexidine digluconate (CHX) pretreatment on the immediate and six-month microshear bond strength (μSBS) of an etch-and-rinse adhesive to sound and eroded dentin. Bovine teeth were subjected to either a control treatment or erosive challenge to create sound and eroded dentin substrates. Specimens received adhesive with or without prior CHX application. μSBS was measured initially and after six months. CHX pretreatment minimized but did not prevent the reduction in μSBS over time, especially for eroded dentin. While CHX helped maintain higher bond strengths after aging, the effectiveness of bonding to
1. Incremental layering techniques are recommended to reduce polymerization shrinkage stress by decreasing the C-factor at each stage of restoration. This allows for stress relief between increments.
2. Flowable composites with lower elastic moduli have been used as intermediate layers to absorb shrinkage stress from subsequent higher modulus resin composite layers through an "elastic cavity wall" effect. However, flowable composites do not significantly reduce stress.
3. Alternative curing methods like soft-start and pulse-delay curing may slightly reduce shrinkage stress by allowing more time for resin flow before full conversion. However, opportunities for stress relief are still limited and conversion levels may be lower.
This study evaluated the Knoop hardness of resin composite restorations photoactivated by different methods when different mold materials were used. Resin composite samples were cured using high-intensity continuous, low-intensity continuous, soft-start, or pulse-delay methods and placed in either a bovine tooth or metal mold. Knoop hardness was measured on the top and bottom surfaces. On the top surface, hardness did not differ between curing methods but was higher for the metal mold. On the bottom, high-intensity continuous curing produced higher hardness than low-intensity continuous, and hardness was influenced by the mold material used. The results indicate that photoactivation method and mold can impact hardness values of resin composite restorations.
Comparison of Different Dentin Pretreatment Protocols on the Bond Strength of...Indian dental academy
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.
The document summarizes a clinical study that evaluated a packable resin composite material called SureFil for posterior dental restorations over a period of 3 years. Fifty-five restorations were placed in 36 patients and evaluated periodically according to the Ryge criteria. After 3 years, 40 of the 47 remaining restorations were rated as excellent, with only 6% failure rate. The study concluded that SureFil packable resin composite can be considered successful for Class I and II restorations with acceptable clinical performance over 3 years.
This document summarizes a study that evaluated the influence of different curing methods on the post-polymerization shrinkage stress of a composite resin. Specifically, it:
1) Compared stress levels immediately after curing and after 5 minutes using different curing methods (continuous QTH light, soft-start QTH light, intermittent QTH light, and xenon plasma arc light).
2) Found that all curing methods resulted in significantly higher stress levels after 5 minutes compared to immediately after curing.
3) Determined that xenon plasma arc light resulted in the greatest increase in stress over 5 minutes, while continuous QTH light produced the smallest increase.
Bioactive effects of a calcium/sodium phosphosilicate on the resin–dentine in...DrMarkHogan
This study evaluated, through microtensile bond strength (μTBS) testing, the bioactive effects of a calcium/sodium phosphosilicate (BAG) at the resin–dentine interface after 6 months of storage in phosphate buffer solution (PBS). Confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) were also per- formed. Three bonding protocols were evaluated: (i) RES-Ctr (no use of BAG), (ii) BAG containing adhesive (BAG-AD), and (iii) BAG/H3PO4 before adhesive (BAG-PR). The dentin-bonded specimens were prepared for μTBS testing, which was carried out after 24 h or 6 months of storage in PBS. Scanning electron microscopy ultramorphology analysis was performed after debonding. Confocal laser scanning microscopy was used to evaluate the morphological and nanoleakage changes induced by PBS storage. High μTBS values were achieved in all groups after 24 h of storage in PBS. Subsequent to 6 months of storage in PBS the specimens created using the BAG-AD bonding approach still showed no significant reduction in μTBS. Moreover, specimens created using the BAG-AD or the BAG-PR approach showed an evident reduction of nanoleakage after prolonged storage in PBS. The use of BAG-containing adhesive may enhance the durability of the resin–dentine bonds through therapeutic/protective effects associated with mineral deposition within the bonding interface and a possible interference with collagenolytic enzyme activity (matrix metalloproteinases) responsible for the degradation of the hybrid layer.
Development of a processed composite restorationIoannis Skliris
This document summarizes the principles and clinical procedures for bonding laboratory-processed composite restorations. It discusses the importance of optimizing the adhesion between the restoration and tooth structure through proper surface preparation and moisture control. A key factor in the long-term success of these restorations is creating a strong, durable bond between the tooth, resin cement, and restoration material. The document outlines the clinical steps for etching and applying adhesive to both the tooth and restoration to achieve this bond. It also addresses factors like restoration fit and finishing/polishing that influence marginal integrity and wear resistance.
This study investigated the effect of material chemistry and prolonged setting time on the permanent deformation of six light-body elastomeric impression materials after stretching. The materials tested were subjected to 80% stretching either after the manufacturer's recommended setting time or after 5 minutes of setting. Polyether materials showed significantly higher permanent deformation than vinyl polysiloxane materials. Extending the setting time reduced permanent deformation for materials with a polyether backbone but not for vinyl polysiloxanes. Increasing the setting time may improve elastic recovery of polyether impression materials.
The study evaluated the Knoop hardness and bond strength of methacrylate- and silorane-based composites when photoactivated by different methods. Bond strength was tested using a push-out test on restored bovine teeth, and Knoop hardness was measured on the top and bottom of restorations. The photoactivation methods did not affect bond strength or hardness within the same composite. The silorane-based composite Filtek P90 showed higher bond strength but lower hardness than the methacrylate-based Filtek Supreme. The photoactivation method did not influence results for either composite.
The document describes a case study of a dental restoration procedure using semi-direct techniques and bioactive materials for a patient undergoing radiotherapy treatment for oral cancer. It discusses how the patient's oral health was compromised by the radiation treatment and chemotherapy. The restorative treatment involved selectively removing radiation-induced caries using RMGIC for cervical lesions and a semi-direct resin composite technique for a posterior tooth. The semi-direct technique improved marginal adaptation and reduced clinical time and patient discomfort compared to direct placement. The case study demonstrates the benefits of these materials and techniques for restoring teeth in oncology patients undergoing radiotherapy.
The document is a proof cover sheet for a journal article on the influence of preheating bonding agents on the degree of conversion and bond durability in dental cavities. It requests that the author carefully check the proofs, limit changes to corrections of errors, and confirm that the author list is correct. It also includes two queries asking the author to provide an institutional email address and history date for the article.
The effect of finishing and polishing on the decision to replace existing ama...Ashley Mark
This study evaluated the influence of finishing and polishing procedures on the decision to replace existing amalgam restorations. Twenty amalgam restorations from 6 patients were photographed before and after being polished. 27 clinicians and students reviewed the before and after photos and indicated whether replacement was needed. Before polishing, 44% of restorations were deemed replaceable, but after polishing this decreased significantly to 21%, with secondary caries being the main reason for replacement. The study concluded that finishing and polishing reversed the decision to replace many old amalgam restorations.
This study evaluated the influence of cavity configuration factor (C-Factor) and light activation technique on the polymerization contraction forces of a resin composite. Resin composite was placed in molds with different C-Factors and polymerized using either a continuous light pulse or pulse delay technique. Lower contraction forces were found with lower C-Factors and when using pulse delay technique, which allows for stress relief as the resin flows during polymerization. Higher C-Factors resulted in higher contraction forces regardless of light technique, as there was insufficient free space for stress relief. The combination of low C-Factor and pulse delay technique produced the lowest contraction forces.
This document summarizes factors for successful bonding of indirect dental restorations using adhesive cementation. It discusses advantages of adhesive cementation, factors to consider when planning for adhesive versus passive cementation, and provides an overview of current adhesive strategies for resin cements. Key factors discussed include the adhesive system used, compatibility with bonding agents, polymerization mechanism of the cement, and shade matching the clinical situation. Immediate dentin sealing is presented as a promising approach that seals dentin before impression taking.
This study evaluated the effect of four different placement techniques (bulk, oblique incremental, centripetal incremental, and split horizontal incremental) on marginal microleakage in class II composite restorations. 40 teeth were restored using the four techniques and tested for microleakage. The results showed that incremental placement techniques had lower microleakage than bulk placement. Among incremental techniques, split horizontal placement showed the lowest microleakage scores. Microleakage was also lower at occlusal margins compared to gingival margins across all techniques. The study concluded incremental placement is better than bulk for reducing microleakage, and split horizontal incremental technique showed the least amount of microleakage.
This document discusses various materials used for vital pulp therapy (VPT). It begins by outlining the ideal properties of a pulp capping agent, such as maintaining pulp vitality and stimulating reparative dentin formation. Classic materials like calcium hydroxide, zinc oxide-eugenol, and polycarboxylate cement are described along with their disadvantages. More recent bioactive bioceramic materials like mineral trioxide aggregate (MTA), Biodentine, and Endosequence are then discussed and compared to calcium hydroxide, with studies showing higher success rates for reparative dentin formation and less inflammation with bioceramics. The document concludes by mentioning recent advances in VPT including the
Effect Of Solvent Type On Microtensile Bond Strength Of TotalEtch One-Bottle ...iosrjce
IOSR Journal of Dental and Medical Sciences is one of the speciality Journal in Dental Science and Medical Science published by International Organization of Scientific Research (IOSR). The Journal publishes papers of the highest scientific merit and widest possible scope work in all areas related to medical and dental science. The Journal welcome review articles, leading medical and clinical research articles, technical notes, case reports and others.
O documento discute técnicas de reanatomização estética de dentes anteriores com resina composta. Inclui etapas como planejamento com fotografias e modelos, confecção de mock-ups, condicionamento ácido, aplicação de adesivos e resinas de diferentes cores e translucidez, fotoativação, acabamento e polimento. O objetivo é melhorar a autoestima do paciente por meio de um tratamento minimamente invasivo e previsível.
Grau de Conversão de cimento resinoso - Degree of Conversion - resin cementEduardo Souza-Junior
This study evaluated the effect of different light curing units and use of chemical catalysts on the degree of conversion of two dual-cured resin luting cements, RelyX ARC and Panavia F. Sixty disk-shaped specimens of each cement were cured with an argon ion laser, LED, or halogen light through a composite disk. The degree of conversion was measured using FTIR spectroscopy. Panavia F without catalyst cured with LED or laser showed significantly lower conversion than other groups. RelyX ARC showed similar high conversion with all light sources and use of catalyst. To achieve satisfactory conversion, Panavia F requires use of chemical catalyst and halogen light.
[1] O artigo descreve um caso clínico de remodelação do sorriso com resina composta direta, com acompanhamento de dois anos. [2] O tratamento envolveu análises facial, dentolabial e cromática detalhadas, confecção de enceramento diagnóstico e mock-up para planejamento e aprovação da paciente. [3] Após a etapa restauradora, o resultado estético mostrou-se satisfatório e natural ao longo do tempo.
Este documento descreve um caso clínico de resolução estética do sorriso de uma paciente através da confecção de coroas cerâmicas reforçadas com dissilicato de lítio nos dentes superiores. O tratamento teve como objetivo devolver cor, forma e harmonia ao sorriso, corrigindo problemas como alteração de cor, diastemas e restaurações deficientes.
1. O documento apresenta um relato de caso sobre um procedimento de contorno cosmético realizado para melhorar a estética do sorriso de uma paciente sem a necessidade de restaurações.
2. Inicialmente, observou-se desarmonia no tamanho, formato e áreas de reflexão de luz dos dentes anteriores superiores da paciente.
3. Em seguida, foram simulados desgastes nos modelos de estudo para planejar o procedimento. Pequenos desgastes seletivos foram então realizados nos dentes da paciente
The document summarizes a study that evaluated the effects of cigarette smoke exposure on the microhardness and color of dental enamel. Fifteen bovine enamel fragments were exposed to the equivalent of 50 cigarettes over five days using a smoking machine. Testing found that exposed enamel fragments had a significant decrease in microhardness and an unacceptable increase in color change compared to pre-exposure measurements. The study concludes that cigarette smoke exposure can negatively impact the microhardness and coloring of dental enamel.
Este documento descreve o planejamento e execução de laminados cerâmicos para restaurar o sorriso de uma paciente. Inclui fotos do antes e depois do tratamento, detalhes do planejamento digital do sorriso, preparo dos dentes, confecção dos laminados e resultados finais.
[1] O documento descreve a técnica de estratificação natural com resinas compostas para restaurar dentes anteriores fraturados. [2] A técnica envolve aplicar camadas incrementais de resinas de diferentes cores e opacidades para reproduzir a aparência natural do esmalte e dentina. [3] Imagens ilustram cada etapa do procedimento, desde a preparação do dente até o acabamento final, demonstrando como a técnica pode restaurar com sucesso a forma, cor e função do dente danificado.
O documento fornece diretrizes sobre a fotoativação de materiais resinosos utilizados em odontologia restauradora. É importante selecionar uma fonte de luz adequada e seguir as instruções do fabricante para cada material, realizando a fotoativação por tempo suficiente para garantir a polimerização completa. A técnica correta de fotoativação promove maior durabilidade dos tratamentos e satisfação do paciente.
This study evaluated the Knoop microhardness and microshear bond strength of different dual-cured resin luting systems and a flowable resin when bonding leucite-reinforced ceramic to enamel. The results showed that the Scotchbond/RelyX ARC system had the highest bond strengths while the Single Bond/Filtek Z350 Flow showed the lowest. Thermocycling reduced bond strengths for all groups. Panavia F showed the highest hardness values and the flowable resin showed the lowest. Dual-cured resin luting systems provided more reliable bonding and hardness than the flowable resin.
Este documento descreve um caso clínico no qual laminados cerâmicos foram utilizados para melhorar a estética do sorriso de uma paciente. Laminados de cerâmica feldspática foram preparados e cimentados nos dois incisivos centrais superiores para restaurar a cor, forma e tamanho originais dos dentes e proporcionar harmonia ao sorriso. O resultado final mostrou uma reabilitação estética satisfatória com boa adaptação marginal e detalhes semelhantes aos dentes naturais.
Este documento descreve dois casos clínicos de restaurações cerâmicas:
1) Foram confeccionadas coroas cerâmicas para os dentes 11 e 12, que necessitavam de preparo dental devido ao escurecimento.
2) Uma lente de contato cerâmica sem preparo dental foi confeccionada para o dente 21 para melhorar a estética. Ambas as restaurações utilizaram cerâmica reforçada com dissilicato de lítio para restaurar a harmonia do sorriso.
As etapas de moldagem e cimentação de laminados cerâmicos são cruciais para o resultado final do tratamento. A moldagem deve ser realizada com silicones para garantir precisão, enquanto a cimentação requer condicionamento das superfícies dentais e cerâmicas, aplicação de sistema adesivo e cimento resinoso fotoativado. Um protocolo correto nestas etapas é essencial para proporcionar estabilidade estética e funcional de longo prazo às restaurações cerâmicas.
This study evaluated the accuracy of the Joypex 5 multifrequency electronic apex locator (EAL) in determining working length in primary teeth. The working lengths of 25 root canals in 14 primary molars were measured directly using a file and microscope and electronically using the EAL. There was no statistically significant difference between the two measurement methods. The intraclass correlation coefficient showed almost perfect agreement between the direct and EAL measurements. The study concluded that the Joypex 5 EAL showed adequate accuracy in determining root length in primary teeth.
The study evaluated the influence of eugenol-containing endodontic sealers and resin luting strategies on the pull-out bond strength of glass fiber posts to dentin. Sixty-four bovine teeth were treated with either gutta-percha alone or with a eugenol-based sealer, then fiber posts were cemented using different adhesive systems and resin cements. The eugenol sealer did not affect bond strength regardless of the luting strategy. Resin cements from the same manufacturer resulted in similar bond strengths, while a dual-cured cement paired with a two-step adhesive yielded higher strength than a self-cured cement. The eugenol sealer did
Este documento relata um caso clínico de restauração estética direta de um dente anterior fraturado utilizando a técnica de estratificação de resina composta. O paciente sofreu fratura no dente 11 e optou-se por reconstruir a morfologia do dente com resina composta ao invés de tentar colar o fragmento, que não foi recuperado. A restauração foi realizada em camadas mimetizando a estrutura dentária natural para um resultado estético.
This study evaluated the effect of selective acid etching of enamel and dentin on the microtensile bond strength of a self-adhesive resin cement. Bovine teeth were used to test three cementation strategies: cement alone, acid etching prior to cement, or a conventional resin cement as a control. Bond strength was measured and found to be higher for enamel than dentin, with no difference between strategies for each substrate. Acid etching did not improve bonding of the self-adhesive cement to enamel or dentin.
Este documento descreve um caso clínico de reabilitação estética anterior com coroas totais de cerâmica reforçada por dissilicato de lítio. O paciente apresentava desgaste excessivo nos dentes anteriores, comprometendo a estética e função. As etapas do tratamento incluíram preparo dental, moldagem, confecção das coroas de cerâmica reforçada por dissilicato de lítio e cimentação adesiva. O resultado final proporcionou estética e função satisfatórias.
Cell Therapy Expansion and Challenges in Autoimmune DiseaseHealth Advances
There is increasing confidence that cell therapies will soon play a role in the treatment of autoimmune disorders, but the extent of this impact remains to be seen. Early readouts on autologous CAR-Ts in lupus are encouraging, but manufacturing and cost limitations are likely to restrict access to highly refractory patients. Allogeneic CAR-Ts have the potential to broaden access to earlier lines of treatment due to their inherent cost benefits, however they will need to demonstrate comparable or improved efficacy to established modalities.
In addition to infrastructure and capacity constraints, CAR-Ts face a very different risk-benefit dynamic in autoimmune compared to oncology, highlighting the need for tolerable therapies with low adverse event risk. CAR-NK and Treg-based therapies are also being developed in certain autoimmune disorders and may demonstrate favorable safety profiles. Several novel non-cell therapies such as bispecific antibodies, nanobodies, and RNAi drugs, may also offer future alternative competitive solutions with variable value propositions.
Widespread adoption of cell therapies will not only require strong efficacy and safety data, but also adapted pricing and access strategies. At oncology-based price points, CAR-Ts are unlikely to achieve broad market access in autoimmune disorders, with eligible patient populations that are potentially orders of magnitude greater than the number of currently addressable cancer patients. Developers have made strides towards reducing cell therapy COGS while improving manufacturing efficiency, but payors will inevitably restrict access until more sustainable pricing is achieved.
Despite these headwinds, industry leaders and investors remain confident that cell therapies are poised to address significant unmet need in patients suffering from autoimmune disorders. However, the extent of this impact on the treatment landscape remains to be seen, as the industry rapidly approaches an inflection point.
Travel vaccination in Manchester offers comprehensive immunization services for individuals planning international trips. Expert healthcare providers administer vaccines tailored to your destination, ensuring you stay protected against various diseases. Conveniently located clinics and flexible appointment options make it easy to get the necessary shots before your journey. Stay healthy and travel with confidence by getting vaccinated in Manchester. Visit us: www.nxhealthcare.co.uk
Osteoporosis - Definition , Evaluation and Management .pdfJim Jacob Roy
Osteoporosis is an increasing cause of morbidity among the elderly.
In this document , a brief outline of osteoporosis is given , including the risk factors of osteoporosis fractures , the indications for testing bone mineral density and the management of osteoporosis
Our backs are like superheroes, holding us up and helping us move around. But sometimes, even superheroes can get hurt. That’s where slip discs come in.
- Video recording of this lecture in English language: https://youtu.be/Pt1nA32sdHQ
- Video recording of this lecture in Arabic language: https://youtu.be/uFdc9F0rlP0
- Link to download the book free: https://nephrotube.blogspot.com/p/nephrotube-nephrology-books.html
- Link to NephroTube website: www.NephroTube.com
- Link to NephroTube social media accounts: https://nephrotube.blogspot.com/p/join-nephrotube-on-social-media.html
8 Surprising Reasons To Meditate 40 Minutes A Day That Can Change Your Life.pptxHolistified Wellness
We’re talking about Vedic Meditation, a form of meditation that has been around for at least 5,000 years. Back then, the people who lived in the Indus Valley, now known as India and Pakistan, practised meditation as a fundamental part of daily life. This knowledge that has given us yoga and Ayurveda, was known as Veda, hence the name Vedic. And though there are some written records, the practice has been passed down verbally from generation to generation.
Local Advanced Lung Cancer: Artificial Intelligence, Synergetics, Complex Sys...Oleg Kshivets
Overall life span (LS) was 1671.7±1721.6 days and cumulative 5YS reached 62.4%, 10 years – 50.4%, 20 years – 44.6%. 94 LCP lived more than 5 years without cancer (LS=2958.6±1723.6 days), 22 – more than 10 years (LS=5571±1841.8 days). 67 LCP died because of LC (LS=471.9±344 days). AT significantly improved 5YS (68% vs. 53.7%) (P=0.028 by log-rank test). Cox modeling displayed that 5YS of LCP significantly depended on: N0-N12, T3-4, blood cell circuit, cell ratio factors (ratio between cancer cells-CC and blood cells subpopulations), LC cell dynamics, recalcification time, heparin tolerance, prothrombin index, protein, AT, procedure type (P=0.000-0.031). Neural networks, genetic algorithm selection and bootstrap simulation revealed relationships between 5YS and N0-12 (rank=1), thrombocytes/CC (rank=2), segmented neutrophils/CC (3), eosinophils/CC (4), erythrocytes/CC (5), healthy cells/CC (6), lymphocytes/CC (7), stick neutrophils/CC (8), leucocytes/CC (9), monocytes/CC (10). Correct prediction of 5YS was 100% by neural networks computing (error=0.000; area under ROC curve=1.0).
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Histololgy of Female Reproductive System.pptxAyeshaZaid1
Dive into an in-depth exploration of the histological structure of female reproductive system with this comprehensive lecture. Presented by Dr. Ayesha Irfan, Assistant Professor of Anatomy, this presentation covers the Gross anatomy and functional histology of the female reproductive organs. Ideal for students, educators, and anyone interested in medical science, this lecture provides clear explanations, detailed diagrams, and valuable insights into female reproductive system. Enhance your knowledge and understanding of this essential aspect of human biology.
These lecture slides, by Dr Sidra Arshad, offer a quick overview of the physiological basis of a normal electrocardiogram.
Learning objectives:
1. Define an electrocardiogram (ECG) and electrocardiography
2. Describe how dipoles generated by the heart produce the waveforms of the ECG
3. Describe the components of a normal electrocardiogram of a typical bipolar lead (limb II)
4. Differentiate between intervals and segments
5. Enlist some common indications for obtaining an ECG
6. Describe the flow of current around the heart during the cardiac cycle
7. Discuss the placement and polarity of the leads of electrocardiograph
8. Describe the normal electrocardiograms recorded from the limb leads and explain the physiological basis of the different records that are obtained
9. Define mean electrical vector (axis) of the heart and give the normal range
10. Define the mean QRS vector
11. Describe the axes of leads (hexagonal reference system)
12. Comprehend the vectorial analysis of the normal ECG
13. Determine the mean electrical axis of the ventricular QRS and appreciate the mean axis deviation
14. Explain the concepts of current of injury, J point, and their significance
Study Resources:
1. Chapter 11, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 9, Human Physiology - From Cells to Systems, Lauralee Sherwood, 9th edition
3. Chapter 29, Ganong’s Review of Medical Physiology, 26th edition
4. Electrocardiogram, StatPearls - https://www.ncbi.nlm.nih.gov/books/NBK549803/
5. ECG in Medical Practice by ABM Abdullah, 4th edition
6. Chapter 3, Cardiology Explained, https://www.ncbi.nlm.nih.gov/books/NBK2214/
7. ECG Basics, http://www.nataliescasebook.com/tag/e-c-g-basics
1. Ó
Operative Dentistry, 2011, 36-2, 231-238
Effect of the Curing
Method and Composite
Volume on Marginal and
Internal Adaptation of
Composite Restoratives
E Souza-Junior M Souza-Regis RC Alonso
´
A Freitas M Sinhoreti L Cunha
Clinical Relevance
Modulated curing methods were shown to be effective to reduce gap formation in composite
restoratives.
´
Eduardo Jose Souza-Junior, DDS, MS, Department of Restor-
ative Dentistry, Piracicaba Dental School, University of SUMMARY
Campinas-UNICAMP, Piracicaba–SP, Brazil The aim of the present study was to evaluate
´
Marcos Ribeiro de Souza Regis, DDS, School of Dentistry, the influence of curing methods and composite
University of Bahia, Salvador–BA, Brazil volumes on the marginal and internal adapta-
Roberta Caroline Bruschi Alonso, DDS, MS, PhD, Department tion of composite restoratives. Two cavities
˜
of Biomaterials, Bandeirante University of Sao Paulo - with different volumes (Lower volume: 12.6
UNIBAN, SP, Brazil mm3; Higher volume: 24.5 mm3) were prepared
Anderson Pinheiro de Freitas, DDS, MS, PhD, associate on the buccal surface of 60 bovine teeth and
professor, School of Dentistry, University of Bahia, Salva- restored using Filtek Z250 in bulk filling. For
dor–BA, Brazil each cavity, specimens were randomly as-
Mario Alexandre Coelho Sinhoreti, DDS, MS, PhD, associate signed into three groups according to the
professor, Department of Restorative Dentistry-Dental Ma- curing method (n¼10): 1) continuous light (CL:
terials Division, Piracicaba Dental School, University of
27 seconds at 600 mW/cm2); 2) soft-start (SS: 10
Campinas-UNICAMP, Piracicaba–SP, Brazil
seconds at 150 mW/cm2+24 seconds at 600 mW/
*Leonardo Goncalves Cunha, DDS, MS, PhD, associate profes-
¸ cm2); and 3) pulse delay (PD: five seconds at
sor, Department of Restorative Dentistry-Dental Materials
´
150 mW/cm2+three minutes with no light+25
Division, University of Alagoas-FOUFAL, Maceio, AL, Brazil
seconds at 600 mW/cm2). The radiant exposure
*Corresponding author: BR 101 Norte-Km 97, Tabuleiro
for all groups was 16 J/cm2. Marginal adapta-
´
do Martins-Maceio -AL-57072-970, Brazil; e-mail:
leonardogcunha@yahoo.com tion was measured with the dye staining gap
procedure, using Caries Detector. Outer mar-
DOI: 10.2341/10-107-L
gins were stained for five seconds and the gap
2. 232 Operative Dentistry
percentage was determined using digital im- niques) are determinant factors with regard to
ages on a computer measurement program shrinkage stress magnitude.4 Even after light expo-
(Image Tool). Then, specimens were sectioned sure, the polymerization reaction continues from five
in slices and stained for five seconds, and the minutes to 24 hours, increasing the degree of
internal gaps were measured using the same conversion and the volumetric shrinkage and also
method. Data were submitted to two-way anal- leading to a significant increase of stress at the
ysis of variance and Tukey test (p,0.05). Com- tooth/composite interface.5,6
posite volume had a significant influence on The cavity configuration (C-factor) was considered
superficial and internal gap formation, de- the main determinant of shrinkage stress in com-
pending on the curing method. For CL groups, posite restoratives.7 However, Braga and others8
restorations with higher volume showed high-
showed that the volume of composite is also strongly
er marginal gap incidence than did the lower
related to shrinkage stress and microleakage of
volume restorations. Additionally, the effect of
restorations. The higher the composite volume, the
the curing method depended on the volume.
greater the amount of monomer to convert and the
Regarding marginal adaptation, SS resulted in
higher the stress generated on the bonded interface.8
a significant reduction of gap formation, when
Moreover, previous studies9,10 concluded that, for
compared to CL, for higher volume restora-
similar volumes, bulk or incremental filling have
tions. For lower volume restorations, there
similar results on marginal adaptation.
was no difference among the curing methods.
For internal adaptation, the modulated curing Shrinkage stress is also regulated by the curing
methods SS and PD promoted a significant protocol. Low light intensity or modulated curing
reduction of gap formation, when compared to methods reduce the polymerization rate of compos-
CL, only for the lower volume restoration. ites, consequently reducing the stress rate generat-
Therefore, in similar conditions of the cavity ed11,12 and improving the marginal adaptation of
configuration, the higher the volume of com- composite restoratives.13 In this sense, modulated
posite, the greater the gap formation. In addi- curing methods such as soft-start (SS) and pulse
tion, modulated curing methods (SS and PD) delay (PD) have been proposed.7,14-16
can improve the interfacial quality of compos- Yoshikawa and others17 reported that the SS
ite restorations through the reduction of in- curing method promotes better marginal sealing of
ternal gaps in lower volume composite cavo-surface margins of composite restoratives. In
restoratives. addition, this curing method can provide similar
properties, such as hardness and residual monomer
INTRODUCTION concentration, when compared to the conventional
Resin composites have been widely used in direct continuous curing method.18
esthetic restorative procedures. However, polymeri- The PD curing method is a variation of the SS
zation shrinkage still harms the interfacial quality, protocol. In this method, a lag period ranging from
creating adaptation problems.1 When this shrinkage 10 seconds to five minutes is utilized between low
takes place under confinement, as a result of and high light exposure scenarios.19,20 Previous
bonding to cavity walls, stresses on the bond studies19,21 have associated this method with re-
interface will develop,2 potentially leading to gap duced gap formation through the reduction on
formation, marginal pigmentation, and secondary shrinkage stress. Cunha and others11 showed that
caries. The presence of gaps on the tooth/resin the PD method provided the greatest reduction in
interface is considered the first sign of restoration the stress rate of dental composites, with no
failure.3 significant reduction in the degree of conversion.
Although the polymerization shrinkage is the Although several studies1,11,13,17,19,22-24 have
cause of adaptation problems of composite restora- pointed out the benefits of the modulated photoacti-
tions, it is an inherent characteristic of the composite vation, this issue has not yet been completely
and directly related to the degree of conversion. established as successful. One of the reasons is
Therefore, the actual factor to be managed is the because composites behave differently when subject-
shrinkage stress generated by the polymerization ed to modulated photoactivation.25 In this sense,
shrinkage. some studies showed no positive effect of modulated
Composite formulation and volume, curing proto- photoactivation on shrinkage stress26 or gap forma-
cols, and restorative procedures (as insertion tech- tion.27-29 In addition, Stansbury and others30 stated
3. Souza-Junior Others: Curing Methods and Composite Volume on Marginal Adaptation 233
that modified photo-curing protocols, including SP, Brazil) mounted in a high-speed hand piece
stepped or pulsed irradiation programs, appear to (Kavo, Joinville, SC, Brazil) under constant air-
have limited potential to reduce the overall stress water cooling, as follows:
developed if comparable levels of conversion are
achieved compared to a standard protocol. Also, Lower volume cavity—4 mm diameter31 mm deep,
Froes-Salgado and others31 have suggested that
´ volume of 12.6 mm3, prepared using tip #3053.
modulated curing methods may also reduce the Higher volume cavity—5 mm diameter31.25 mm
overall degree of conversion, not just the rate, and deep, volume of 24.5 mm3, prepared using tip
this may contribute to the reduced stress. Converse- #4054.
ly, several studies5,11,14,24 showed that modulated Diamonds tips were replaced after every fifth
curing methods cause no reduction in the degree of preparation. At the superficial margin, the cavity
conversion or in mechanical properties if the energy walls formed a 908 angle with the dentin surface
dose is not reduced. Thus, a definitive answer about plane, while the internal cavity angles were rounded
the effect of modulated curing protocols has not been based on the design of the diamond tip used. If any
determined; therefore, further evaluation of this sign of pulp exposure was noticed during cavity
issue is necessary. preparation, the specimen was discarded.
The aim of the present study was to evaluate the
influence of modulated curing methods and compos- Restorative Procedure
ite volume on superficial and internal adaptation of Each specimen was restored using an etch-and-rinse
composite restoratives. The first hypothesis tested adhesive system (Adper Single bond 2, batch #3HR,
was that the higher the volume of composite, the 3M/ESPE, St Paul, MN, USA), applied in accordance
higher the gap formation due to shrinkage stress. with the manufacturer’s instructions: the cavity was
The second tested hypothesis was that modulated etched with 35% phosphoric acid gel (Scotchbond
curing methods can improve the marginal and Etchant, 3M/ESPE) for 15 seconds, rinsed for 10
interfacial quality of composite restorations. In seconds, and blot-dried. The adhesive system was
addition, aiming to compare the studied factors, the applied twice with a five-second interval in between,
third hypothesis was that situations related to dried carefully with air for 15 seconds in order to
higher shrinkage stress, such as cavities with higher remove residual solvent (observing a glossy surface),
volumes, would experience higher benefits of using and light cured for 20 seconds using a LED curing
modulated curing methods. ˜o
unit (Ultrablue IS, DMC, Sa Paulo, SP, Brazil) with
a power density of 600 mW/cm2. Both cavities were
MATERIALS AND METHODS bulk filled with a hybrid composite (Filtek Z250,
Specimen Preparation shade A3, batch #3AM, 3M/ESPE) and teeth were
randomly assigned into six groups (n¼10), according
Sixty bovine incisors were selected, cleaned, and to the curing method and composite volume. Curing
stored in a 0.5% chloramine T solution at 48C for no methods are described in Table 1, and for this step
more than a week. Roots were sectioned off 1 mm the same LED curing unit previously described was
under the cement enamel junction using a double- used, with a radiant exposure of around 16 J/cm2, for
˜o
face diamond saw (K. G. Sorensen, Sa Paulo, SP, all curing methods. The power density was frequent-
Brazil). The buccal surface was ground on a water-
cooled mechanical polisher (Metaserv 2000, Buehler,
UK Ltd, Lake Bluff, IL, USA) using 80-, 180-, 320-, Table 1: Curing Methods Used in the Present Study
and 600-grit silicon carbide (SiC) abrasive paper
(Carbimet Disc Set, #305178180, Buehler, UK Ltd) Curing Method Power Density and Time Exposure
in order to expose a flat dentin area of at least 8 mm.
These teeth were observed on a stereomicroscope Continuous Light 600 mW/cm2 during 27 s
(Zeiss, Manaus, AM, Brazil), at 253 magnification, to
observe whether the enamel had been completely Soft-Starta 150 mW/cm2 during 10 sþ600 mW/cm2
during 24 s
removed.
Two kinds of cylindrical cavities with different Pulse Delaya 150 mW/cm2 during 5 sþ3 min light
volumes and the same C-factor (2.0) were prepared offþ600 mW/cm2 during 25 s
on the flattened surface using cylindrical diamond a
The reduction of power density was obtained using neutral density filters.
˜
tips (#3053 and #4054; K. G. Sorensen, Sao Paulo,
4. 234 Operative Dentistry
ly checked by a radiometer (Demetron Research Table 2: Means in % of Marginal Gap Length (Standard
Corp, Danbury, CT, USA). Deviation) on Superficial Margins of Cavities with
After the light curing procedures, specimens were Different Volumes and Curing Methods
stored in distilled water at 378C for 24 hours and
were then finished under water using 600- and 1200- Continuous Light Pulse Delay Soft-Start
grit SiC sandpaper and polished with 1- and 0.5-lm
diamond pastes using a polish cloth under water. Low Volume 8.62 (1.42) Ab 8.13 (2.43) Aa 7.44 (1.88) Aa
Specimens were ultrasonically cleaned for five
minutes between finishing and polishing steps. High Volume 17.76 (2.64) Aa 9.10 (2.42) Ba 4.70 (0.69) Ca
Mean values followed by different small letters in the column and capital
Evaluation of Marginal and Internal letters in the row differ statistically among themselves for the Tukey test at
the level of 5%. Values in parentheses represent standard deviations.
Adaptation
Marginal adaptation was measured using a staining
technique. A 1.0% acid red propylene glycol solution formation that was statistically greater compared to
(Caries Detector, Kuraray Co., Osaka, Japan) was the cavity with lower volume. No difference was
applied at the restoration margins for five sec- observed when SS and PD were compared in the
onds.14,18,32 Specimens were then rinsed in tap water different volumes. Additionally, no difference among
and gently blow-dried. Digital images of the dyed curing methods was observed for the lower volume
restorations with 2400-megapixel resolution were restorations. Concerning internal adaptation (Table
obtained using a scanner (HP ScanJet G4050, 3), the modulated curing methods SS and PD showed
Hewlett-Packard Company, Palo Alto, CA, USA). a reduction on gap formation, when compared to CL,
The length of the dye-stained gaps along the cavity in lower volume cavities. However, in higher volume
margins was measured (mm) from the images using cavities, no significant difference among curing
the UTHSCSA Image tool software, version 2.0 methods was observed. In addition, from the results
(alpha 2_ September 1997), developed by the De- of internal adaptation, it was possible to observe that
partment of Dental Science at The University of the higher volume cavity group presented gap
Texas Health Science Center (San Antonio, TX, formation that was statistically greater compared
USA). The length of the gap formed was calculated to the cavity with lower volume for the SS and PD
as a percentage of the entire margin length. curing methods. For CL, no difference between
higher and lower restoration volume was detected.
After the evaluation of gap formation at superficial
margins, the restorations were cut in the buccal- DISCUSSION
lingual direction in slices (1 mm thick) using a
cutting machine (ISOMET 1000, Buehler, UK LTD, An important factor to consider in promoting the
Lake Bluff, IL, USA) in order to obtain two slices of clinical success of resin composite restorations is a
each restoration. On each slice, Caries Detector was satisfactory marginal and internal adaptation. The
applied to stain the internal gaps, and the same presence of gaps is considered the first sign of
procedures described previously were accomplished restoration failure, clinically evidenced by marginal
for the evaluation of the internal adaptation of the staining.13 It has been accepted that a detectable
composite restorations. The obtained data (marginal marginal gap would lead to interfacial leakage.3,13
and internal adaptation) were transformed (arcsine
root x/100) in order to obtain normal distribution and
Table 3: Means in % of Gap Length (Standard Deviation)
were submitted to two-way analysis of variance and on Internal Margins of Cavities with Different
Tukey tests at 5% significance. Volumes and Curing Methods
RESULTS Continuous Light Pulse Delay Soft-Start
None of the curing methods was capable of ensuring
a perfect marginal seal of restorations. Table 2 shows Low volume 13.53 (3.18) Aa 5.10 (2.26) Ba 3.96 (1.68) Ba
that marginal gap formation in restorations cured
using SS and PD was significantly reduced, when High volume 9.60 (1.52) Aa 9.92 (1.54) Ab 7.24 (1.82) Ab
compared to restorations cured using continuous Mean values followed by different small letters in the column and capital
light (CL), in the higher volume cavity group. For letters in the row differ statistically among themselves for the Tukey test at
the level of 5%. Values in parentheses represent standard deviations.
CL, the higher volume cavity group presented gap
5. Souza-Junior Others: Curing Methods and Composite Volume on Marginal Adaptation 235
Clinically, the bacterial leakage along the adhesive stress. In addition, gap formation at the pulpal wall
interface has been related to a severe pulpal and axiopulpal angles may promote fluid flow in the
response. dentin tubules, resulting in postoperative sensitivi-
In addition to the importance of bacterial leakage, ty.39
in vitro microleakage tests have not been accepted as The composite used in the present study, Filtek
predictive of restoration failure, because they can Z250, has high inorganic filler volume content (60%)
show overestimated results as a result of dentin and monomeric system based on components with a
permeability to low-molecular-weight colorants/ high molecular weight (BisGMA, BisEMA, UDMA),
dyes.32 In this sense, evaluating the presence of which leads to a low volumetric shrinkage (about
gaps is considered to be more reliable because it 2.2%), according to manufacturer’s information.
should be considered as the first sign of restoration However, Filtek Z250 presents a high concentration
failure that can be clinically evidenced by marginal of photoinitiators in order to offer a satisfactory cure
staining.3 Thus, the identification of early marginal in 20 seconds of light exposure, leading to a fast
changes could facilitate the prognosis of the longev- photo-curing reaction and, consequently, fast devel-
ity/stability of a composite restoration, because it has opment of shrinkage stress.5
been accepted that a detectable marginal gap will In addition, the use of bovine teeth could be
lead to interfacial leakage.32-34 considered a limitation of this study. One may argue
Composite shrinkage stress can damage the that using this substrate is not as accurate as using
interfacial quality of composite restorations, com- human teeth when different interactions between
promising the durability of the restorative treat- bonding systems and tooth substrate are compared.
ment. In the present study, none of the curing However, in the present study, the adhesive bonding
techniques or employed material volumes was able system and substrate were standardized for all
to ensure a perfect sealing of the interfacial margin groups, thereby standardizing the interaction be-
of composite restorations. Internal gap formation tween them. The major aim of this study was to
was particularly located at pulpal wall and axiopul- evaluate composite characteristics under confine-
pal angles, which are problematic areas for compos- ment cured with different methods. Therefore, the
ite insertion.32 At the pulpal floor, gap formation is observed differences were caused by the tested
related to difficulty with the adhesion due to an variables: volume of composite and curing method.
increase in tubular density and diameter and In this sense, bovine teeth were selected because
proportional reduction in intertubular dentin.35 This they are a suitable substrate for the type of test used,
condition allows the shrinkage stress to overcome they are easier to obtain than human teeth, and
the bond strength. Gap formation on the axio-pulpal their use does not result in ethical problems.
angle could be attributed to the difficulty of accom- According to Reeves and others,40 bovine dentin is
modating composite in this region. Indeed, previous an adequate substitute for human teeth in adhesion
studies1,36,37 related the axio-pulpal angle to an area tests. However, it has been observed that it is more
of significant difficulty related to the insertion of difficult to ensure good marginal quality using
composite, and this difficulty of composite accommo- bovine dentin, and this fact could explain the high
dation could promote a gap between the composite marginal gap values. Considering that, a successful
and the bonding agent/cavity wall, increasing the technique with bovine teeth tends to be even more
probability of gap formation. successful than can be achieved using human teeth.
Additionally, gap formation at these sites is also In addition, the use of bovine incisors has been
related to shrinkage vectors, as observed by Chiang supported by several authors.36,39,41
and others.38 These authors explained that the In this study, we tested the hypothesis that the
composite shrinks with an upward movement, which higher the volume of composite, the greater the gap
is determined by two conditions: 1) debonding at the formation, and this hypothesis was accepted. How-
bottom of the cavity and 2) intact adhesion to the ever, it should be noted that the reduced gap
enamel margins. As soon as the debonding occurs, formation associated with lower volume cavities
the intact adhesion will cause the upward move- occurred differently depending on the curing method
ment. This can be explained by the fact that the employed. For CL groups, marginal gap formation
bonding agent usually exhibits a higher bond was greater for higher volume cavities. However, for
strength to enamel than to dentin. Therefore, SS and PD groups, a higher percentage of gap
adhesion to the enamel remains intact while the formation was observed in higher volume cavities, to
bond to dentin is lost as a result of the contraction internal margins. The reduction in gap formation
6. 236 Operative Dentistry
associated with lower volume cavities can be ex- to Lim and others,19 an initial irradiance of 150
plained based on the reduction in shrinkage stress in mW/cm2 is too high to significantly reduce the
a lower volume of composite.8 magnitude of shrinkage stress. However, in the
The effect of modulated curing methods depends present work, even when using an initial irradiance
on the volume of the cavity. In higher volume of 150 mW/cm2, gap formation was significantly
cavities, modulated curing methods generated re- decreased when compared to use of the CL curing
duction of superficial gap formation, and in lower method. And this gap reduction is attributed to a
volume cavities, these methods generated reduction reduction in shrinkage stress due to a slower curing
rate.5,11 The low modulus phase (pre-gel stage) is
of internal gap formation. Therefore, the second
extended, allowing stress to be relieved by polymer
tested hypothesis was accepted, because modulated
flow and deformation.
curing methods reduced gap formation, but this
reduction occurs in different modes, depending on Despite the advantageous effects of the modulated
the volume of the cavity. Considering that, the third curing methods, some concerns have to be addressed.
hypothesis, related to a superior benefit of modulat- Studies have pointed out that the efficacy of these
ed curing methods in situations of higher shrinkage methods varies according to formulation, which
stress, cannot be accepted. The benefits of modulated limits the results of the present study to the specific
methods occur differently in both cavities. In higher material used.19 Another potential problem is reduc-
volume cavities, the benefits occur in the external tion of polymer cross-link density related to modu-
margins (marginal gap formation is reduced by lated curing methods,14 which can render the
modulated curing methods). However, in lower polymer network more susceptible to degradation.
volume cavities, the benefits occur in the internal However, it should be considered that the main
margins (internal gap formation is reduced by cause of adhesive restoration failure is the debond-
modulated curing methods). ing of the composite-tooth interface,12 and it is
directly related to gap formation. Thus, even if less
For CL, the fast polymerization process decreases
cross-link density is formed,14 a similar degree of
the time allowed for viscous flow and leads to a rigid
conversion,7 better bond strength values,7,12 and
polymer matrix in a few seconds.40 So, shrinkage
improved marginal adaptation1,13,43 are achieved,
stress starts almost immediately after polymeriza-
and these benefits can be considered superior to the
tion, and a significant part of the shrinkage occurs afore-mentioned problems.
after the polymer matrix has reached a significant
level of rigidity, which causes higher shrinkage CONCLUSION
stress and may culminate in greater gap formation,
as observed in the present study. Based on the results, it can be concluded that the
higher the volume of composite, the greater the gap
The benefits of modulated curing methods have
formation. In a general way, exposing the composite
been related to the increased ability of the composite
to CL intensity (600 mW/cm2) during the entire
to flow, delaying the pre-gel stage,8 and to reduced
irradiation period can damage the bonding interface,
stress rates associated with these methods.7 Con- thereby increasing marginal gap formation. Howev-
versely to CL photoactivation, this scenario pro- er, none of the curing methods tested were able to
motes a slower formation of the polymer network ensure perfect sealing of margins, although modu-
and cross-links, favoring better conditions, compared lated curing methods (SS and PD) could reduce gap
to molecular adaptation, within the polymeric chain formation, depending on the volume of the cavity.
that has been developed under the cavity confine-
ment.42 The low initial intensity employed for these
(Accepted 21 October 2010)
curing methods could reduce the stress rate and
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