Hybrid Composite Resin Research Articles

Influence of using different bonding systems and composites on the margin integrity and the mechanical properties of selectively excavated teeth in vitro

ObjectivesSelective (incomplete) caries excavation reduces the risk of pulpal complications, but might compromise the properties of teeth or restorations. Different restorative approaches might be required after selective instead of complete excavation. We compared margin integrity, micro-leakage and fracture resistance of selectively excavated and differently restored premolars in vitro. MethodsIn 72 extracted human premolars, artificial residual lesions were induced on pulpo-axial walls of standardized cavities. Teeth were restored using one of three bonding systems (OptiBond FL, Clearfil SE Bond, G-aenial Bond) and a fibre-enforced (EverX) or standard hybrid composite resin (Filtek Z250). After thermo-mechanical cycling, groups (n=12) were compared regarding their gingivo-cervical margin integrity (proportion of acceptable margins), microleakage depth, and fracture resistance, with statistical evaluation using generalized linear modelling. ResultsMargin integrity was significantly influenced by the bonding system (p<0.001), but not by the composite (p=0.105). Proportions of acceptable margins were increased in teeth restored with OptiBond FL (median [25th/75th percentiles]: 93 [78/100%]) or Clearfil SE (82 [60/94]%) compared with G-aenial Bond (43 [15/74%]; p<0.05). Neither bonding systems nor composites significantly influenced leakage depth in enamel (p=0.749/0.569) or dentine (p=0.112/0.909). Fracture resistance was significantly influenced by bonding system (p=0.008) and composite (p=0.001), and was higher in teeth restored using OptiBond FL (mean [SD]: 1210 [336]N) compared with Clearfil SE (1007 [208]N) or G-aenial Bond (1023 [281]N, p<0.05), and using EverX (1182 [314]N) instead of Filtek Z250 (979 [228]N; p<0.01). ConclusionsBonding systems which perform well in completely excavated teeth also yielded good results for selectively excavated teeth in vitro. Using fibre-enforced composites to restore selectively teeth increased fracture resistance. Clinical significanceBonding systems which perform well in completely excavated teeth are also suitable for restoring selectively excavated teeth. Using fibre-enforced composites seems suitable for increasing the fracture resistance of selectively excavated teeth and their restorations.

Compressive strength measurements of hybrid dental composites treated with dry heat and light emitting diodes (LED) post cure treatment

Hybrid composites are mostly used on large cavities as restorative dental materials, whether it is used directly or indirectly. The mechanical properties of composite resin shall increase if it is treated with post cure treatment. The aim of this study is to evaluate compressive strength differences between dry heat and Light Emitting Diodes (LED) treatment on the hybrid dental composite. A quasi-experimental was applied on this research with a total of 30 samples that were divided into two groups. Each sample was tested using LLOYD Universal Testing Machine with 1 mm/min speed to evaluate the compressive strength. The compressive strength results were marked when the sample was broken. The results of two groups were then analyzed using t-test statistical calculation. The results of this study show that post cure treatment on hybrid composite using LED light box (194.138 MPa) was lower than dry heat treatment (227.339 MPa), which was also significantly different from statistical analysis. It can be concluded that compressive strength of LED light box was lower than dry heat post-cure treatment on the hybrid composite resin.

Preparation and characterization of glass fiber-coir hybrid composites by a novel and facile Prepreg/Press process

The present study explored the preparation of glass fiber-coir reinforced unsaturated polyester resin hybrid (GCU) composites with a novel Prepreg/Press fabrication process. Flexural, impact and thermal-mechanical properties of GCU composites were investigated. Coir reinforced unsaturated polyester resin (CU) composites was also prepared with the same process to explore the enhancement effect of glass fabric on the mechanical properties of coir-based composites. The effect of fabrication pressure on the mechanical properties of CU and GCU composites was examined. Micromorphology and interfacial reaction of the composites were analyzed. It is shown that GCU composites fabricated with the Prepreg/Press process have excellent flexural strength (185.0 MPa), MOE (18.3 GPa), and impact strength (67.2 kJ/m2). The mechanical properties of GCU composites increased with the increase of applied pressure up to 0.8 MPa in the Prepreg/Press process. However, further increase of applied pressure led to the decrease in mechanical properties. The addition of glass fabrics to GCU composites showed 419 % improvement in flexural strength, 708 % improvement in MOE and 562 % improvement in impact strength over coir-based composites. The micromorphology study proved that the poor interfacial bonding between coir and matrix led to the low mechanical properties of coir-based composites.

A randomized controlled three year evaluation of “bulk-filled” posterior resin restorations based on stress decreasing resin technology

ObjectiveThe objective of this randomized controlled prospective clinical trial was to evaluate the efficacy of a flowable resin composite (SDR) bulk fill technique in posterior restorations and to compare it intraindividually with a conventional 2mm resin composite curing technique in a 3-year follow up. Materials and methodsThirty-eight pairs Class II and 15 pairs Class I restorations were placed in 38 patients with a mean age of 55.3 years (range 32–87). Each patient received at random at least two, as similar as possible, Class II or Class I restorations of two restorative techniques. In all cavities a single step self-etch adhesive (Xeno V) was applied. In one of the cavities of each pair, a flowable resin composite (SDR) was placed, in bulk increments up to 4mm as needed to fill the cavity 2mm short of the occlusal cavosurface. The occlusal part was completed with a nano-hybrid resin composite (Ceram X mono) layer. In the second cavity, the hybrid resin composite was placed in 2mm increments. The restorations were evaluated using slightly modified USPHS criteria at baseline and then yearly during 3 years. Caries risk and parafunctional habits of the participants were estimated. ResultsAfter three years, 76 Class II and 28 Class I restorations could be observed. One molar resin composite-only tooth showed post-operative sensitivity during 3 weeks for temperature changes and occlusal forces. Two failed Class II molar restorations in the resin composite-only group were observed during the first year, one cusp fracture and one resin composite fracture. An annual failure rate of 1.3% was found for the resin composite only restorations and of 0% in the bulk-filled restorations (n.s.). Ten participants were estimated as having high caries risk and eleven showed active bruxing habits. SignificanceThe 4mm bulk-fill technique with the flowable resin composite SDR showed highly clinical effectiveness, which was comparable during the 3-year follow-up with the 2mm resin composite layering technique.

Prefabricated Composite Resin Veneers – A Clinical Review

This clinical technique article is focused on the use of prefabricated veneers to enhance the esthetic appearance of the anterior dentition in patients who needed an alternative esthetic solution more affordable than traditional porcelain veneers. Because prefabricated composite veneer systems have been recently introduced, they are not widely used. The Componeer system (Coltene, Altstätten, Switzerland) contains thin pre-polymerized hybrid composite shells, several shades of a direct hybrid composite resin, an etch-and-rinse adhesive system, and restorative accessories including finishing points and disks. The prefabricated restorations can be customized in the mouth for color and shape. The technique described in this article can be used to restore function and esthetics in one office visit. The prefabricated composite veneer technique has some of the advantages of direct composite restorations, as only one session is required without the need to take impressions to send to the dental laboratory. This new treatment option may open new opportunities for dental professionals and their patients. However, it is paramount to carry out controlled clinical studies with this restorative technique prior to recommending it without restrictions in general practice. The clinical technique described in this paper has the potential for being used routinely to lengthen anterior teeth, to correct malpositioned teeth, to mask discolorations, and to close diastemas. The technique can also be used to restore extensive caries lesions and tooth fractures, and to refurbish large old anterior restorations, especially when other treatment options are out of reach for the patient for financial reasons.

Influencia del uso de Papacarie en el sellado marginal de obturaciones directas

El propósito de la investigación fue, comparar el sellado marginal de obturaciones directas, realizadas con la técnica sándwich, después de la remoción de tejido cariado con el gel de papaina (Papacarie) y el método convencional rotatorio. Para lo cual se seleccionaron 20 premolares humanos recientemente extraídos, con lesiones cariosas que comprometían la superficie oclusal y proximal. La muestra fue dividida aleatoriamente en dos grupos: Grupo 1: se hizo la remoción de dentina cariada, mediante la técnica químico mecánica utilizando el gel Papacarie. Grupo 2: remoción de dentina cariada mediante la técnica convencional, con instrumentos rotatorios. Después de la remoción del tejido cariado por ambas técnicas se colocó una restauración directa utilizando la técnica sándwich: colocación de ionómero de vidrio modificado por resina, sistema adhesivo de un solo paso y resina compuesta microhibrida. Posteriormente, después de un proceso de termociclado, los especimenes fueron sometidos a filtración pasiva del colorante azul de metileno, por 3 días, seccionados en sentido mesiodistal a través de la restauración, y observados de acuerdo a grados de filtración del colorante en la interfase diente-obturación tanto en el margen oclusal como el gingival de la preparación, con la ayuda del microscopio estereoscopio. El análisis de los resultados indicaron que: El gel Papacarie permitió la remoción químico mecánica de tejido carioso en la preparación de cavidades para obturación. Sin embargo, influyó significativamente en una mayor frecuencia de filtración de colorante comprometiendo el sellado marginal de las obturaciones, comparado con el método de remoción convencional rotatorio.

The Surface Hardness Value of a light cured Hybrid Composite Resin after 12 Hours Immersion in three alcohol-free mouthwashes

3 Abstract Introduction: Mouthwashes which prevent and control caries and periodontal diseases are commonly used even without professional prescription. Long-term use of mouth-washes may cause softening of restorative composites and lowering the longevity of restoration. The aim of this study was evaluation of surface hardness value of a microhybride composite (Filtek Z250) a er 12 hours immersion in three kinds of alcohol-free mouthwashes. Materials and Methods: 72 Cylinderical speci- mens of a microhybride composite 5mm wide

Comparison of pattern of failure of resin composite restorations in non-carious cervical lesions with and without occlusal wear facets

ObjectivesMany studies have reported the clinical problems associated with resin composite restorations in NCCLs. None has compared these clinical problems in NCCLs with and without occlusal wear facets. The present study sets out to determine the proportion of NCCLs that presents occlusal wear facets, and to compare the failure pattern of resin composite restorations in NCCLs with and without occlusal wear facets. MethodsTeeth with NCCLs were classified into two groups, those with and without occlusal wear facets. Both groups were restored using micro hybrid resin composite. The restorations were evaluated at the end of 2 years concerning post-operative sensitivity, retention, marginal integrity, marginal discolouration, wear, and secondary caries, using the USPHS criteria. Statistical analysis compared the ratings of each criterion between the two groups using Pearson's χ2 or Fisher's exact test. ResultsAbout one-third (33.8%) of teeth with NCCLs presented with occlusal wear facets, more NCCLs with occlusal wear facets in mandibular teeth (44.7%) than maxillary teeth (24.5%). Retention rate of composite resin restorations in NCCLs with and without occlusal wear facets was 63.9% and 74.4% respectively at the end of 2 years. More marginal discolouration and defects were observed in restorations in NCCLs with occlusal wear facets, the differences were not statistically significant (p>0.05). ConclusionsThe decline in ratings of marginal discolouration and defects, and the lower retention rate of restorations in NCCLs with occlusal wear facets may support the role of occlusal stress and tooth flexure as a cause of failure of restorations in NCCLs. Clinical significanceThe ability to distinguish between stress induced lesions (with occlusal wear facets) and other cervical lesions will have important ramifications for the success of their restorations because they are not subjected to the same physical forces that are responsible for the deterioration of the restoration.

The effect of soda immersion on nano hybrid composite resin discoloration

Background: Composite resin is the tooth-colored restorative material which most of the people are fond of due to their aesthetic value. The composite resin discoloration may happen because of the intrinsic and extrinsic factors. Soda water is one of the beverages which can cause the composite resin discoloration. Purpose: The study was aimed to determine the effect of soda immersion on nano hybrid composite resin discoloration. Methods: The study was an experimental laboratory study using 100 shade A3 nano hybrid composite resin specimens with the diameter of 5 mm and density of 2mm. The samples were divided into 5 groups, each group was immersed in different beverages. The beverages were mineral water; lemon-flavored soda; strawberry-flavored soda; fruit punch-flavored soda; and orange-flavored soda for 3, 7, 14 and 21 days respectively, in the temperature of 37o C. The discoloration measurement utilizes Spectrophotometer, Vita Easy Shade, and uses CIEL*a*b* method. Results: The result showed that the duration of immersion in soda had an effect on the Nano hybrid composite resin discoloration. Strawberry and fruit punch- flavored soda were the most influential components toward the discoloration. Nevertheless, the generally-occurred discoloration was clinically acceptable (∆E ≤ 3,3). Conclusion: The study suggested that the soda immersion duration has effect on Nano hybrid composite resin discoloration.Latar belakang: Resin komposit adalah material sewarna gigi yang diminati masyarakat karena memiliki nilai estetik yang baik. Perubahan warna resin komposit dapat terjadi karena faktor intrinsik dan ekstrinsik. Minuman soda merupakan salah satu minuman yang dapat menyebabkan perubahan warna pada resin komposit. Tujuan: Tujuan dari penelitian ini untuk meneliti perubahan warna resin komposit nanohibrida akibat perendaman dalam minuman soda. Metode: Metode yang digunakan pada penelitian ini adalah eksperimental laboratorik dengan menggunakan 100 spesimen resin komposit nanohibrida shade A3 berdiameter 5 mm dan tebal 2 mm. Sampel dibagi dalam 5 kelompok, masing-masing kelompok direndam dalam minuman yang berbeda, yaitu direndam dalam air mineral, soda lemon, soda strawberi, soda fruitpunch, dan soda jeruk selama 3, 7, 14 dan 21 hari, dalam suhu 37o C. Pengukuran perubahan warna menggunakan Spectrophotometer, Vita Easy Shade dengan metode CIEL*a*b*. Hasil: Hasil penelitian menunjukkan bahwa lama perendaman pada minuman soda berpengaruh terhadap perubahan warna resin komposit nanohibrida. Soda yang paling berpengaruh terhadap perubahan warna adalah soda strawberi dan soda fruitpunch. Namun perubahan warna yang terjadi secara umum masih dapat diterima secara klinis (∆E ≤ 3,3). Simpulan: Hasil penelitian ini menunjukkan bahwa lamanya waktu perendaman mempengaruhi perubahan warna pada resin komposit nanohibrida.

Effect of configuration factor on gap formation in hybrid composite resin, low‐shrinkage composite resin and resin‐modified glass ionomer

Polymerization shrinkage is one of the important factors in creation of gap between dental structure and composite resin restorations. The aim of this study was to evaluate the effect of configuration factor (C-factor) on gap formation in a hybrid composite resin, a low shrinkage composite resin and a resin modified glass ionomer restorative material. Cylindrical dentin cavities with 5.0mm diameter and three different depths (1.0, 2.0 and 3.0mm) were prepared on the occlusal surface of 99 human molars and the cavities assigned into three groups (each of 33). Each group contained three subgroups depend on the different depths and then cavities restored using resin modified glass ionomer (Fuji II LC Improved) and two type composite resins (Filtek P90 and Filtek Z250). Then the restorations were cut into two sections in a mesiodistal direction in the middle of restorations. Gaps were measured on mesial, distal and pulpal floor of the cavities, using a stereomicroscope. Data analyses using Kruskal-Wallist and Mann-Whitney tests. Increasing C-factor from 1.8 to 3.4 had no effect on the gap formation in two type composite resins, but Fuji II LC Improved showed significant effect of increasing C-factor on gap formation. Taken together, when C-factor increased from 1.8 up to 3.4 had no significant effect on gap formation in two tested resin composites. Although, Filtek P90 restorations showed smaller gap formation in cavities walls compared to Filtek Z250 restorations. High C-factor values generated the largest gap formation. Silorane-based composite was more efficient for cavity sealing than methacrylate-based composites and resin modified glass ionomer.

The influence of finishing/polishing time and cooling system on surface roughness and microhardness of two different types of composite resin restorations.

Objective:The aim of this study was to evaluate the effect of finishing time and polishing time on surface roughness and microhardness of nanofilled and hybrid resin composites.Materials and Methods:Hundred disk composite specimens from micro hybrid composite and nanohybrid composite were prepared, 50 for each type of composite. The specimens were divided into five groups according to the time of finishing and polishing (immediate, 15 min, 24 h and dry). Composite under the Mylar strip without finishing and polishing was taken as the control group. Surface roughness was measured with environmental scanning electronic microscope (ESEM) and microhardness was determined using Vickers Microhardness Tester. Data collected were statistically analyzed by t-test and one-way analysis of variance (ANOVA) followed by Turkey's post hoc test.Results:Smooth surface with low hardness was obtained for the group under Mylar strip without finishing and polishing. The highest roughness was recorded for delayed finishing and polishing for both composites. Immediate finishing and polishing increased the surface hardness more than that in the control group in both types of composites. Dry finishing reduced the hardness significantly for micro hybrid composite, but resulted in the highest surface hardness for nanofilled composite.Conclusion:Immediate finishing and polishing under coolant resulted in the best surface smoothness and hardness values in micro hybrid composite; however, immediate dry finishing and polishing gave the best smoothness and hardness values in nanohybrid composite.

Caries detector dyes: Do they stain only the caries?

Objective: Caries detector (CD) dyes aid in caries diagnosis by staining the organic matrix of less mineralized infected dentine. However, detector dyes are not specific to bacteria and can discolor surrounding healthy tissues as dentino-enamel junction or the circumpulpal dentine. Possible discoloring effect of CD dye over restorative materials have not been evaluated until date. The aim of this study was to investigate the staining effects of four commercial CD dyes Caries Detector (CAD), Caries Marker (CAM),SEEK (SEE), Sable Seek (SES) on a variety of tooth colored restorative materials; Filtek Valux Plus (VLX), Filtek Z250 (Z25), Filtek Silorane (SIL) Fuji IX (FUJ). Materials and Methods: A total of 40 disc-shaped specimens were prepared from each restorative material. After 24 h distilled water storage, baseline color was measured according to the Commission International de l'Eclairage L* a* b* system by using a reflection spectrophotometer. Each CD dye was applied to 10 samples of each composite group for 10 s and applications were repeated for 2 times. Before the final color measurements, all samples was rinsed and dried. Color differences (ΔE) were measured and analyzed the data with two-way analysis of variance and Tukey honest significant difference post-hoc tests. Results: Independent of dyes, perceptible color changes were observed in glass ionomer restorative material (FUJ) (ΔE ab * > 3.3). CAD, CAM and SES caused staining on highly triethylene glycol dimethacrylate monomer containing composite resin (VLX). Silorane based restorative material (SIL) and micro hybrid resin composite (Z25) were more resistant to discoloration then VLX and FUJ (P < 0.05). Conclusion: CD dyes may cause discolorations in some restorative materials and should be used with maximum care.

The Shear Bond Strengths of Composite Bonded to Dentine Following Treatment with Two Dentine Occluding Desensitizing Toothpastes

Aim: This study determined whether prior brushing with desensitizing toothpastes (Sensodyne Rapid Relief and Colgate Pro-Relief) affected the shear bond strengths of composite to dentine surfaces after appropriate use of two different dentine bonding agents (SingleBond and PQ-1). Materials and Methods: Sixty caries free molar teeth were cleaned, disinfected and embedded in individual cylinders of polymethylmethracyrlate. The occulsal surfaces were flattened to expose dentine and finished down with 600 grit silicone carbide paper. The teeth were randomly divided into six groups of 10 teeth each. Two groups served as control where dentine surfaces were brushed with pumice slurry. Of the remaining 4 groups, 2 groups were brushed with Sensodyne Rapid Relief and 2 groups brushed with Colgate Pro-Relief. The dentine surfaces were brushed to simulate 2 weeks of twice-daily toothpaste use. The specimens in each of the control groups and experimental groups were subjected to dentine bonding procedures (Single Bond or PQ-1), and application of hybrid composite resin (Z-250) according to the manufacturer’s instructions. A universal material testing machine, with a cross head speed of 0.05 mm/min was used to determine shear bond strengths. Results: Mean shear bond strengths ranged from 5.71 MPa (Colgate pretreatment, composite bonded with Single Bond) to 9.07 MPa (Sensodyne pretreatment, composite bonded with Single Bond). Results showed neither of the main effects, of toothpaste type or bonding agent were significant (p > 0.05) but their interaction was (F = 4.25, p = 0.02). Post hoc analysis showed that teeth brushed with the Sensodyne group, treated with the unfilled dentine bonding agent had a significantly higher bond strength than those treated with the filled dentine bonding agent. Conclusion: The desensitizing toothpastes that use the mechanism of occlusion of open dentinal tubules in the preliminary management of tooth sensitivity should not have an adverse effect on future restorative treatment modalities.

The comparison of the effects of different whitening toothpastes on the micro hardness of a nano hybrid composite resin.

Aim:The aim of this study was to compare the micro hardness of a nanohybrid composite resin after brushing with two herbal and one non-herbal whitening toothpastes.Materials and Methods:We divided Eighty disk-shaped specimens of a nanohybrid composite (Tetric N Ceram, Ivoclar Vivadent, Asia) into 4 groups of 20 specimens each: Groups A, B, C, and D. Group A was control, Group B was brushed with Colgate total advanced whitening (Colgate-Palmolive (India) Limited), Group C with Salt and Lemon, Dabur (Dabur International Limited, Dubai, UAE), and Group D with HiOra Shine, Himalaya (The Himalaya Drug Company, India). The specimens were polished using medium, fine, and superfine discs (Sof-lex, 3M, ESPE, USA) and subsequently placed at 37°C in distilled water. They were brushed for 2 minutes twice daily with a soft motorized toothbrush (Colgate 360 sonic power battery-operated tooth brush, Colgate Palmolive, India) for 30 days. The samples were rinsed under running water to remove the toothpaste and stored in distilled water at 37°C until the readout was taken on the Vickers's hardness tester for microhardness.Results:The results revealed that the difference among the groups was statistically significant (P < 0.001). Tukey's test showed that reduction in microhardness for Group B was significantly higher than that for Group C and Group D (P < 0.001).Conclusion:Within the limitations of this study, non-herbal whitening toothpaste had a greater impact on the microhardness of nanohybrid resin composite than herbal whitening toothpastes.

An in-vitro evaluation of microleakage among nano ceramics and nano hybrid composite resins in Class V cavities

Background: Prevention of micro-leakage plays an important role in the success of composite restorations. This has led scientists to find newer composite restorative materials. Materials and Methods: Twenty-four human freshly extracted molar was randomly selected for this study. The teeth were stored in 0.1% thymol solution diluted in 0.4% saline. Class V cavities were prepared at the cemento-enamel junction on the buccal surfaces of each tooth. One coat of seventh generation bonding agent G-bond (GC Japan) was applied to all the samples. The samples were randomly divided into two groups of 12 samples each. All the samples were restored with composite resin using single increment technique as per the grouping. The teeth were then stored at 370°C water, except when they were removed from storage and subjected to thermo cycling for 1000 cycles in water between 50°C and 550°C for 30 s in each bath and 15 s transfer between bath. After thermo cycling, the samples were dried superficially, and two coats of nail varnish applied to the entire sample surface, leaving a 1 mm window around the restored cavity margins. All teeth were immersed in 2% methylene blue solution for 24 h at room temperature. The teeth were sectioned in the bucco – lingual direction across the center of the restoration using a slow speed saw (Isomet 1000, Buchler, USA). The sectioned teeth were examined by two calibrated inspectors for dye penetration levels. Results: Mann–Whitney U-test showed that there was no significant difference in dye leakage between Group I and Group II. However, at experimental level, when observing the enamel and dentinal margin, Group II showed a greater degree of leakage than Group I. Conclusion: In the present study, it was observed that self-etch adhesive systems and single increment technique are beneficial as they help in reducing the application time and technique related sensitivity.

Enamel Hypoplasia: A Case Report

ABSTRACT Enamel hypoplasia (EH) is a defect in tooth enamel. EH can occur on any tooth or may affect multiple teeth. It can appear white, yellow or brownish in color with a rough or pitted surface. The quality of the enamel is affected as well as the quantity. Envi ronmental and genetic factors that interfere with tooth formation are thought to be responsible for EH which include, trauma to the teeth and jaws, intubation of premature infants, infections during pregnancy or infancy, poor prenatal and postnatal nutrition, hypoxia, exposure to toxic chemicals and a variety of hereditary disorders. The most frequent cause of EH in a particular child is diffi cult to determine. The most conservative treatment consists of bonding a tooth colored material is to protect the tooth from further wear or sensitivity or crowns. This paper presents a case report of a restorative treatment of EH using hybrid composite resin to mask color alteration and enamel defects. Keywords: Developmental defects of teeth, enamel defects, enamel hypoplasia, Turner’s hypoplasia

HPLC ANALYSIS OF ELUTED MONOMERS FROM DENTAL COMPOSITE USING DIFFERENT IMMERSION MEDIA

Numerous factors may play a role in the monomer release of dental materials. The aim of this study is to measure the release of monomers from commercially available hybrid composite resin Tetric Ceram (Ivoclar Vivadent AG, Schaan, Liechtenstein) in the following time schedule, 1 hr, 24 hr, 7 d, and 30 d after the polymerization and observation of the effects of different immersion media on released monomers. Twelve specimen discs were prepared using hybrid composite resin for each analyte in three media [ethanol/water solution (75:25, v/v), distilled water, artificial saliva]. The High Performance Liquid Chromatography (HPLC) method was used for the analysis of released monomers from the hybrid composite resin. All monomers were released in ethanol/water solution with higher efficiency than the other two media, and the highest amount of release was obtained from BisGMA (p < 0.001). Ethanol/water solution which is suggested to simulate the environment of the mouth is the most effective media for monomer release from composite resins.

The effect of two finishing and polishing systems on the surface roughness of two composite resins

Background and objective: The purpose of this study was to evaluate the effect of two finishing and polishing systems on the surface roughness of two different types of&nbsp;composite resins. Methods: Fourty samples of 6 mm in diameter and 2 mm in depth were prepared, 2 types of composite resins were used (nanocomposite and hybrid composite resin). Twenty samples of each type of material were prepared and divided into two main groups and then each main group subdivided randomly into two subgroups of 10 samples each. Ten samples of each material were submitted to finishing by finishing disc. While the other 10 samples of each material were submitted to finishing by finishing bur. Both finishing systems were used with a slow-speed hand piece in a dry field and with a light intermittent pressure for about 15 seconds for each disc and bur. After storage of the samples for 48 hours; the analysis of the surface roughness was carried out, three readings were made on each surface using a stylus tip, and the extension of each reading was 2 mm stroke. Results: There was non significant difference between the groups except there was a significant difference between the two finishing systems when used with hybrid composite. Conclusion: Finishing discs gave best results on nano composite and hybrid composite when compared with finishing diamond bur, with highly significant effect on nano composite.

A 6-year prospective evaluation of a one-step HEMA-free self-etching adhesive in Class II restorations

ObjectiveThe aim of this study was to evaluate the clinical effectiveness of a one-step HEMA-free self-etching adhesive (SEA) placed with a micro-fine hybrid resin composite in Class II restorations. The restorations were compared intraindividually with 2-step HEMA containing SEA-giomer restorations. Material and methodsFifty-four patients with at least one pair of two similar Class II cavities participated (30 men, 24 women; mean age 57.1yrs). A total of 115 Class II composite restorations were placed with (1) a one step HEMA-free adhesive and a micro-fine hybrid resin composite (Gbond/Gradia Direct: 60; GG) and (2) a 2-step HEMA-containing SEA and a giomer (FL Bond/Beautifil: 55; FB). Each participant received in a randomized way at least one restoration with each of the experimental materials. The restorations were evaluated at baseline and yearly during a 6 year followup using modified USPHS criteria. ResultsDuring the 6 years, 111 restorations could be evaluated. No post-operative sensitivity was reported by the participants. Fourteen failed restorations (12.6%) were observed during the follow up, 5 GG (8.5%; 4 premolar and 1 molar teeth) and 9 FB (17.7%; 1 premolar and 8 molar teeth) (p<0.05). Annual failure rate at 6 years were 1.4% for GB and 3.0% for FB. Main reasons of failure were bulk fracture of resin composite for FB and tooth fracture for GB. SignificanceThe HEMA-free SEA-hybrid RC restorations showed good clinical durability in Class II cavities after 6 years. The HEMA-containing SEA-giomer restorations showed a rather high failure frequency.

Effect of chlorhexidine on the 18-month clinical performance of two adhesives.

This study tested the hypothesis that 2% chlorhexidine (CHX) does not affect the 18-month clinical performance of two dentin adhesives, XP Bond (XPB) and XENO V (XEN). A total of 120 noncarious cervical lesions (NCCL) were selected and assigned to 4 groups: (1) XPB; (2) CHX prior to the application of XPB; (3) XEN; (4) CHX prior to the application of XEN. A hybrid composite resin, Esthet•X, was used for all restorations. Restorations were evaluated blindly at 6 and 18 months by two evaluators using the University of North Carolina (UNC)-modified USPHS criteria. Statistical analyses included the Mann Whitney and McNemar nonparametric tests (p < 0.05). At 6 months, 91 (75.2%) restorations were evaluated, while 92 (76.7%) restorations were evaluated at 18 months. The 6-month/18-month overall retention rates (%) were 100/100 for XPB, 96.0/95.0 for CHX+XPB, 100/91.3 for XEN, and 100/95.8 for CHX+XEN with no statistical difference between any pair of groups at each recall. Sensitivity to air improved significantly for groups XPB, XEN, and CHX+XEN from pre-operative conditions to 1 week after insertion, to 6 and to 18 months after inserting. For group CHX+XPB, there was a statistically significant difference only between pre-operative conditions and 1 week after insertion. Marginal adaptation deteriorated for all groups, but no statistically significant differences were found. All other criteria remained statistically similar. The application of CHX prior to the dentin adhesive did not influence the 6-month/18-month clinical performance of the two adhesives.