Randomized controlled split-mouth clinical trial of direct laminate veneers with two micro-hybrid resin composites

Objectives

This randomized, split-mouth clinical study evaluated the survival rate of direct laminate veneers made of two resin-composite materials.

Methods

A total of 23 patients (mean age: 52.4 years old) received 96 direct composite laminate veneers using two micro-hybrid composites in combination with two adhesive resins (Ena-Bond-Enamel HFO: n = 48, Clearfil SE Bond-Miris2: n = 48). Enamel was selectively etched with 38% H₃PO₄ for 30 s, rinsed 30 s and the corresponding adhesive resin was applied accordingly. Existing resin composite restorations in good conditions (small or big) were not removed but conditioned using silica coating (CoJet) and silanized (ESPE-Sil). Restorations were evaluated at baseline and thereafter every 6 months. Additional qualitative analysis was performed using modified USPHS criteria.

Results

Mean observation period was 41.3 months. Altogether, 12 absolute failures were observed [survival rate: 87.5%] (Kaplan–Meier). The survival rates with the two resin composites did not show significant differences [Enamel HFO: 81.2%, Miris2: 93.8%] (p > 0.05). The presence of existing composite restorations on the prepared teeth did not affect the survival rate significantly (intact teeth: 100%, small restorations: 90.6%, big restorations: 82.7%) (p > 0.05). Surface roughness and marginal discolouration were the main qualitative deteriorations observed until the final recall. Secondary caries and endodontic complications did not occur in any of the teeth.

Conclusion

Early findings of this clinical study with the two micro-hybrid composite laminate veneers showed similar survival rate and their clinical performance was not significantly influenced when bonded onto intact teeth or onto teeth with existing restorations with the protocol applied.     

Assessment of laminate technique using glass ionomer and resin composite for restoration of root filled teeth

Objective

To evaluate the open laminate technique using glass ionomer cements (GIC) in association with a low shrink composite for restoring root filled premolars.

Methods

Extensive MOD cavities plus endodontic access and root filling were performed in intact extracted maxillary premolars. Three restoration types were evaluated: (1) resin composite alone; (2) resin-modified GIC (RM-GIC) open laminate plus resin composite; (3) conventional GIC open laminate plus resin composite (n = 8 for all groups and tests). Three tests were conducted to assess restorations: (A) inward cusp deflection during light curing, using DCDTs; (B) fracture strength using a ramped oblique load at 45° to the long axis in a servohydraulic testing machine in comparison with intact and unrestored teeth; (C) proximal marginal leakage using methylene blue dye and the effect of thermocycling. Data were analysed using 1-way ANOVA for cuspal deflection and fracture strength and Fisher's exact test for leakage.

Results

Laminate restorations resulted in significantly less cuspal deflection compared with resin composite (4.2 ± 1.2 μm for RM-GIC and 5.1 ± 2.3 μm for conventional GIC vs. 12.2 ± 2.6 μm for composite, P < 0.001). Fracture strength was not significantly different among all groups. Failure with all restorations was predominantly adhesive at the tooth-restoration interface. The two laminate groups showed significantly better marginal seal than composite alone, but sealing ability of conventional GIC deteriorated after thermocycling.

Conclusions

Laminate restoration of root filled teeth had beneficial effects in terms of reducing cuspal deflection and marginal seal, with acceptable fracture strength.     

Three-year clinical evaluation of a flowable and a hybrid resin composite in non-carious cervical lesions

Objectives

This randomized controlled clinical trial evaluated the 3-year clinical performance of a hybrid (Clearfil AP-X; AP) and a flowable (Clearfil Flow FX; FX) resin composite in 98 non-carious cervical lesions.

Methods

Twenty-two patients, 11 males and 11 females (mean age: 61.9 years, range: 29–78 years) regularly visiting the Nagasaki University Hospital, participated in the study. Each patient received both materials randomly. All restorations (48 restorations for AP and 50 restorations for FX) were placed in conjunction with an all-in-one system (Clearfil S³ Bond) by one dentist. The restorations were blindly evaluated by two examiners at baseline, 6 months, 1, 2 and 3 years using modified USPHS criteria. The data were statistically analyzed using the Cochran's Q-test and Fisher's exact test.

Results

All the patients were examined at each recall. However, five restorations could not be evaluated at 3-year recall as two teeth had been extracted and three restorations had been lost. The only minor problem was the integrity of the enamel margin. The incidence and extent of marginal staining increased with time, but it was still superficial. Marginal staining occurred adjacent to 11 restorations for AP and 12 restorations for FX after 3 years. Neither lesion size nor depth had influence on marginal staining adjacent to each type of resin composite. There were no significant differences in the clinical performances between AP and FX for each variable.

Conclusions

Under the protocol used in this study, both types of resin composite in conjunction with S³ Bond demonstrated an acceptable clinical performance up to 3 years.     

A split-mouth randomized clinical trial of conventional and heavy flowable composites in class II restorations

Objective

The aim of this study was to evaluate the 2-year clinical performance of class II restorations made with a composite resin with two different viscosities.

Methods

47 patients received two class II restorations (n = 94), one made with GrandioSO (conventional viscosity – CV), and the other with GrandioSO Heavy Flow (flowable viscosity – FV), subjecting both materials to the same clinical conditions. The self-etching adhesive Futurabond M was used for all restorations. The composites were inserted using the incremental technique. The restorations were evaluated using the modified USPHS criteria according to the periods: baseline, 6 months, 1 year and 2 years after restorative procedures.

Results

After 24 months, 40 patients attended the recall and 78 restorations were evaluated. In all periods, no secondary caries was observed. After 6 months, there were slightly overall changes of scores for most parameters. After 24 months, the higher number of changes from score Alfa to Bravo was observed for marginal discolouration (32.5% – CV and 39.5% – FV) and colour match (15% – CV and 31.6% – FV), followed by proximal contact (25% – CV and 23.7% – FV) and marginal adaptation (20% – CV and 21.1% – FV). For wear, surface texture and postoperative sensitivity the changes were very small. Just two restorations were lost during the 24-month follow up. Less than 5% of all restorations showed postoperative sensitivity. Chi-square test showed no significant differences between the two materials for all parameters analysed.

Conclusion

After 2 years of clinical service, no significant differences were observed between GrandioSO conventional and GrandioSO Heavy Flow for the parameters analysed. Both materials provided acceptable clinical behaviour in class II restorations.

Clinical Significance

This study presents the possibility of using a flowable composite with high filler content, for performing class II restorations.     

Periapical Status of Non–root-filled Teeth with Resin Composite,Amalgam, or Full Crown Restorations: A Cross-sectional Study of a Swedish Adult Population

Introduction

Experimental studies show that dental pulp cells respond unfavorably to contact with resin composite restorative material. Hypothetically, in a random population, the frequency of apical periodontitis should be higher for teeth restored with resin composite than with amalgam. Therefore, the aim was to compare the periapical status of non–root-filled teeth restored with resin composite, amalgam, or laboratory-fabricated crowns in an adult Swedish population.

Methods

The subjects comprised 440 individuals from a randomly selected sample of 1,000 adult residents of a Swedish county. The type, material, and quality of the restorations were recorded for all non–root-filled teeth by clinical examination and intraoral clinical photographs. Periapical status was evaluated on panoramic radiographs. The association between periapical status and type, material, and quality of the restorations was analyzed using the chi-square test and logistic regression analysis.

Results

There was no significant difference in the frequency of apical periodontitis (AP) between teeth restored with resin composite or amalgam (1.3% and 1.1%, respectively). The frequency of AP for teeth restored with laboratory-fabricated crowns was significantly higher (6.3%). Regression analysis showed no association between AP and resin composite restorations but a significant association with laboratory-fabricated crowns.

Conclusions

The results indicate that the risk of damage to the pulp-dentin complex from exposure to resin composite material and dentin bonding agents shown in experimental studies is not reflected in the clinical setting. However, in the study sample, AP was diagnosed in a significantly higher proportion of teeth restored with laboratory-fabricated crowns.     

Long-term performance of resin based fissure sealants placed in a general dental practice

Objectives

The aim of the present retrospective study was to evaluate the long-term performance of resin based fissure sealants applied in a general dental practice.

Methods

Regularly attending patients visiting the practice between July 2006 until November 2007 and who had received sealants before 1st of January 2000 were included in the study. Date of placement of a sealant in posterior non-discoloured permanent teeth and replacement by a restoration was recorded. In a clinical examination occlusal surfaces were scored for (partial) sealant loss and fissure discolouration. The restoration profile of the patient was assessed as low or high, based on the number of restorations placed per year since the first sealant. Sealants had been applied by four dentists and a dental hygienist.

Results

1204 sealants were placed in 148 patients. After a mean follow-up time of 11.6 years, 41.3% of placed sealants were still fully retained and 11.4% were replaced by a restoration. Failure rates were significantly higher in high than in low restoration profile patients and in molars compared to premolars. In those fissures with lost or partially lost sealants, discolouration frequently occurred (40% of all surfaces) irrespective of restoration profile of the patient.

Conclusions

In this retrospective practice based study, long-term performance of sealants depended on restoration profile of the individual patient and the tooth type (molar versus premolar).     

Selection of dental materials and longevity of replaced restorations in Public Dental Health clinics in northern Sweden

Objectives

To investigate the selection of direct restorative materials and longevity of replaced restorations in relation to operator and patients characteristics.

Methods

A cross-sectional study of treatment in practice, recording all new placements and replacements of direct restorations was performed during 2 weeks comprising all dentists within the Public Dental Health clinics in the county council of Västerbotten.

Results

A total of 2834 data collection sheets, one for each placed restoration, were received with a dropout of 10%. Restorations analyzed in the study were placed in permanent teeth in patients older than 15 years. First restorations placed due to primary caries were 671 and replacements 1536. Class II was the most frequently treated cavity followed by class I. The median longevity of replaced restorations was for amalgam, resin based composite and glass ionomer 16, 6 and 11 years, respectively. High caries risk patients showed shorter longevity for resin based composite restorations than low or moderate risk patients. Secondary caries as reason for failure for class II resin based composite restorations occurred significantly later than loss or fracture. Significantly longer longevity was observed for replaced restorations executed by more experienced dentists.

Conclusions

The use of amalgam was negligible and the material was predominantly replaced by resin based composites in first and replaced restorations. Class II was the most frequent placed and replaced restorations. Caries risk and experience of operator influenced longevity of replacements.     

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

Objective

The 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 methods

Fifty-four patients with at least one pair of two similar Class II cavities participated (30 men, 24 women; mean age 57.1 yrs). 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.

Results

During 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.

Significance

The 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.     

Durability of resin composite restorations in high C-factor cavities: A 12-year follow-up

Objective

Polymerization shrinkage and shrinkage stress has been considered as one of the main disadvantages of resin composite restorations. Cavities with high C-factors increase the risk for interfacial failures. Several restorative techniques have been suggested to decrease the shrinkage stress. The purpose of this study was to evaluate the durability of techniques as oblique layering, indirect curing and/or a laminate with a poly-acid modified resin composite in direct Class I resin composite restorations in a 12-year follow-up.

Methods

Each of 29 patients received one or two pair(s) rather extensive Class I restorations. The first restoration was a poly-acid modified resin composite/resin composite sandwich restoration and the second a direct resin composite restoration. Both restorations, except for the laminate layer, were placed with oblique layering and two-step curing technique. 90 restorations were evaluated annually with slightly modified USPHS criteria during 12 years.

Results

At 12 years, 38 pairs were evaluated. Two cases of slight post-operative sensitivity were observed in one patient. A cumulative failure rate of 2.4% was observed for both the resin composite and the laminate restorations. One laminate restoration showed non-acceptable color match, but was not replaced and one resin composite restoration showed a chip fracture. Five restorations were replaced due to primary proximal caries.

Conclusions

The high failure rate expected in the high C-factor Class I cavity, associated with polymerization shrinkage and shrinkage stress, were not observed. The techniques used resulted in an excellent durability for the Class I resin composite restorations.     

Biodegradation of resin composites and adhesives by oral bacteria and saliva: A rationale for new material designs that consider the clinical environment and treatment challenges

Objective

To survey the recent literature from the late 1980s to recent years in order to assess the relationship between resin degradation, catalyzed by biological factors, and clinical failure outcomes such as marginal breakdown.

Methods

The literature shows that degradation occurs in many manufacturers’ products despite varied vinyl acrylate compositions. The authors examine salivary enzyme activity and their ability to degrade the polymeric matrix of resin composites and adhesives, as well as oral microorganisms that can promote demineralization of the tooth surface at the marginal interface. A survey of recent research relating matrix metalloproteinase (MMPs) to the degradation of the exposed collagen at the dentin adhesive interface is also discussed in the context of marginal breakdown.

Results

The literature provides strong support that together, the above factors can breakdown the marginal interface and limit the longevity of resin composite restorations. The authors have found that the field's current understanding of resin biodegradation in the oral cavity is just beginning to grasp the role of bacteria and enzymes in the failure of resin-based restorations.

Significance

Knowledge of these biodegradation processes is pertinent to areas where innovative strategies in the chemistry of restorative materials are anticipated to enhance the longevity of resin composites.     

Long-term survival of endodontically treated,maxillary anterior teeth restored with either tapered or parallel-sided glass-fiber posts and full-ceramic crown coverage

Objectives

This retrospective study investigated the clinical effectiveness over up to 8 years of parallel-sided and of tapered glass-fiber posts, in combination with either hybrid composite or dual-cure composite resin core material, in endodontically treated, maxillary anterior teeth covered with full-ceramic crowns.

Methods

The study population comprised 192 patients and 526 endodontically treated teeth, with various degrees of hard-tissue loss, restored by the post-and-core technique. Four groups were defined based on post shape and core build-up materials, and within each group post-and-core restorations were assigned randomly with respect to root morphology. Inclusion criteria were symptom-free endodontic therapy, root-canal treatment with a minimum apical seal of 4 mm, application of rubber dam, need for post-and-core complex because of coronal tooth loss, and tooth with at least one residual coronal wall. Survival rate of the post-and-core restorations was determined using Kaplan–Meier statistical analysis.

Results

The restorations were examined clinically and radiologically; mean observation period was 5.3 years. The overall survival rate of glass-fiber post-and-core restorations was 98.5%. The survival rate for parallel-sided posts was 98.6% and for tapered posts was 96.8%. Survival rates for core build-up materials were 100% for dual-cure composite and 96.8% for hybrid light-cure composite.

Conclusions

For both glass-fiber post designs and for both core build-up materials, clinical performance was satisfactory. Survival was higher for teeth retaining four and three coronal walls.     

Marginal leakage of two newer glass-ionomer-based sealant materials assessed using micro-CT

Objectives

To test newer glass-ionomer-based materials as sealant materials. One glass-ionomer sealant was light-cured to obtain an early setting reaction. The null-hypothesis tested was: there is no difference in marginal leakage of sealants produced with high-viscosity glass-ionomer, with and without energy supplied, and that of glass-carbomer, in comparison with resin composite sealants in vitro.

Methods

Materials used were Clinpro^®, Ketac Molar Easymix^® and Glass-Carbomer^®. Sealants were placed in the occlusal surface of 89 molar teeth, thermocycled for 5000 cycles and evaluated using micro-CT for silver nitrate penetration depth at the enamel–sealant interface by two trained evaluators. Data were analysed, using ANOVA and Scheffe's test.

Results

Glass-carbomer sealants showed one or more ‘fracture lines’ in the material and at the enamel–material interface, filled with a kind of transparent, but not black coloured, material. High-viscosity glass-ionomer sealants with and without energy supplied had statistically significantly lower mean marginal leakage scores than sealants produced by composite resin (p < 0.01). No marginal leakage was found in the high-viscosity glass-ionomer group without energy supplied.

Conclusions

The high-viscosity glass-ionomer (Ketac Molar Easymix^®) sealants had lower marginal leakage than resin composite sealants, and should be tested in vivo. Glass-carbomer sealants were non-interpretable.     

Penetration of amalgam constituents into dentine

Objectives

Amalgam restorations are replaced by adhesively placed composite resin restorations at an increasing rate. After the removal of amalgam dentine often shows marked dark discoloration that is attributed to the penetration of corrosion products from overlying amalgams. It is questioned whether penetration of metals into dentine affects the dentine as a substrate for adhesive procedures. This study has been performed to clarify the origin of dark discoloration of dentine by metals from amalgam with special regards to corrosion products.

Methods

A review of the literature has been performed using Medline database. As keywords dentine and amalgam, subsequently combined with penetration, interface, crevice, interaction, corrosion, were used. This was followed up by extensive hand search using reference lists of relevant articles.

Results

Data in the literature have been gathered from extracted amalgam filled teeth and from artificially aged amalgam filled teeth. Corrosion studies have been performed in vivo aged teeth as well as in vitro. Sn is the main element, followed by Zn and Cu, that is consistently found in dentine underneath amalgam, as well as in amalgam corrosion products and in marginal seal deposits. Penetration of elements from amalgam has only been observed in discolored and in demineralised dentine.

Conclusions

Darkly discolored dentine as found underneath amalgam restorations contains amalgam corrosion products and is demineralised. Therefore it must be considered a different substrate for clinical procedures than sound dentine.     

Longitudinal micromorphological 15-year results of posterior composite restorations using three-dimensional scanning electron microscopy

Objectives

Hybrid composite restorations in posterior teeth were evaluated over 15 years using the semiquantitative Clinical, Photographic and Micromorphologic (CPM) index. It was a further aim to quantitate the surface morphology by three-dimensional scanning electron microscopy (3D-SEM).

Methods

Thirty seven hybrid composite restorations (Ketac-Bond/Visio-Molar X, ESPE, Seefeld/Germany) were longitudinally followed up.Parallel to clinical assessment replicas were taken at baseline, after 1, 5, 10 and 15 years and evaluated by SEM, and profilometrical analyses of 3D-SEM data were computed. The profilometrical results were statistically analysed by ANOVA. The level of significance was set to p < 0.05.

Results

The semiquantitative micromorphological evaluation exhibited the most considerable deterioration within the first year and up to 5 years of function. Less change was detected during the next 10 years. The profilometrical quantification showed raising depth of the negative marginal ledges with a mean of 27.2 μm (range 0.6–94.5 μm) after 10 years, with no statistically significant changes from 5 to 10 and 10 to 15 years. The 3D-SEM revealed marginal grooves beneath the level of the ledges (mean 34.5 μm after 5 years) within the bonding zone, exposing enamel margins. Leakages, marginal fractures and surface roughness did not seriously deteriorate the quality of restorations.

Conclusions

Hybrid composite restorations of Class I and II cavities surviving the first five years performed well over 15 years of function. Quantitative 3D-SEM profilometrical measurements revealed the dynamics of marginal behaviour over time.

Clinical significance

Long-term parallel clinical and micromorphological evaluation of posterior composite restorations of Class I and Class II cavities documented the clinical safety and acceptable longevity. The longitudinal 3D micromorphologic assessment of the surface changes and of the marginal behaviour revealed deteriorating as well as improving factors hidden in clinical performance.     

One-year evaluation of two hybrid composites placed in a randomized-controlled clinical trial

Objective

The aim of this prospective randomized-controlled clinical trial is to assess the long-term performance of two direct composite resins in posterior teeth. This study provides a survey of the one-year results.

Materials and methods

A total of 1805 restorations were placed by students in stress-bearing Class I/II cavities (including cuspal-coverage) in molars and premolars in 456 patients. Clinical evaluation was performed at baseline and after one year using modified USPHS criteria. The restorations in each patient were performed either with Ceram X/Prime&Bond NT or Tetric Ceram/Optibond Solo Plus.

Results

After one year 528 fillings with Ceram X and 580 with Tetric Ceram were available for evaluation of substance loss, contact point, color match, marginal staining, marginal adaptation, secondary caries and radiographic examination (if necessary). This represents a recall rate of 61.18% (279 patients). The failure rate per material was 5.3% in the Ceram X group and 6.1% in the Tetric Ceram group. Most of the failures were associated with marginal adaptation/integrity of the filling. A significant influence on the occurrence of a failure was observed for the number of treated teeth per patient, the age of the patient, the mesio-distal extension of the restoration and the tooth position. Gender, material, a previous root canal treatment, the bucco-lingual extension of the filling or cuspal-coverage did not significantly influence the failure rate. Patients attending the first recall were significantly older and had more fillings than patients not attending.

Conclusions

In a group of Class I/II restorations (including cuspal-coverage), there was no significant difference in failure rates between ormocer-based and bis-GMA-based restorative systems after one year. A previous root canal treatment had no negative influence on the failure rate. A longer observation period is indicated to get clear evidence of the long-term performance of these composite resin systems.     

Marginal adaptation of class II cavities restored with bulk-fill composites

Objectives

To determine the marginal adaptation of bulk-fill composites in class II MO cavities.

Methods

Standardized class II MO cavities with bevelled enamel margins were prepared in 40 extracted human molars. The teeth were randomly assigned to one of the five experimental groups (n = 8). The teeth were restored with two horizontal increments of composite (4 mm and 2 mm thickness). The experimental groups were (1st/2nd increment): Gr. A – Venus Bulk-Fill/Venus Diamond; Gr. B – Tetric EvoCeram BulkFill/Tetric EvoCeram; Gr. C – Surefil SDR/Ceram-X; Gr. D – SonicFill; Gr. E – Ceram-X/Ceram-X (control). After finishing procedures, impressions were made using a polyvinyl siloxane and epoxy resin replicas were obtained. Thermo-mechanical stressing was carried out 24 h after the restorative procedure. All specimens were submitted to 240,000 occlusal loading and simultaneous 600 thermal cycles in water at 5 °C and 50 °C. After loading, a new set of epoxy resin replicas was obtained. Scanning electron microscopy was carried out at 200× magnification. Results for the marginal adaptation were expressed as percentages of continuity relative to the exposed interface and analyzed by ANOVA and Duncan post hoc test (p < 0.05).

Results

In enamel, no significant differences were detected before and after thermo-mechanical loading between groups. In dentine, the worst results were observed in Gr. A.

Conclusion

By applying simple layering techniques, bulk-fill materials do not allow better marginal adaptation than a standard composite.

Clinical significance

A new class of resin-base composite (bulk-fill) was recently launched on the market. The bulk-fill composites exhibited adequate marginal adaptation and similar to the results of the standard composite.     

Resin composites: Modulus of elasticity and marginal quality

Objective

To investigate how the modulus of elasticity of resin composites influences marginal quality in restorations submitted to thermocyclic and mechanical loading.

Methods

Charisma, Filtek Supreme XTE and Grandio were selected as they were found to possess different moduli of elasticity but quite similar polymerization contraction. MOD cavities (n = 30) were prepared in extracted premolars, restored and then subjected to thermocyclic and mechanical loading. Marginal quality of the restorations before and after loading was analyzed on epoxy replicas under a scanning electron microscope. The percentage of gap-free margins and occurrence of paramarginal fractures were registered. Modulus of elasticity and polymerization contraction were analyzed with parametric and margins with nonparametric ANOVA and post hoc Tukey HSD or Wilcoxon rank-sum tests, respectively. The number of paramarginal fractures was analyzed with exact Fisher tests (α = 0.05).

Results

Grandio demonstrated significantly more gap-free enamel margins than Charisma and Filtek Supreme XTE, before and after loading (p < 0.01), whereas there was no difference between Charisma and Filtek Supreme XTE (p > 0.05). No significant effect of resin composite (p = 0.81) on the quality of dentine margins was observed, before or after loading. Deterioration of all margins was evident after loading (p < 0.0001). More paramarginal enamel fractures were observed after loading in teeth restored with Grandio when compared to Charisma (p = 0.008).

Conclusions

The resin composite with the highest modulus of elasticity resulted in the highest number of gap-free enamel margins but with an increased incidence of paramarginal enamel fractures.

Clinical significance

The results from this study suggest that the marginal quality of restorations can be improved by the selection of a resin composite with modulus of elasticity close to that of dentine, although an increase in paramarginal enamel fractures can result as a consequence.     

A suitable base material for composite resin restorations: Zinc oxide eugenol

Objective

This in vitro study evaluated the effects of a zinc oxide eugenol (ZOE) base on the mechanical properties of a composite resin restoration.

Methods

Class I cavities were prepared on plastic teeth and filled with ZOE plus composite resin, following standard clinical procedures. The samples were sectioned sagittally and the ZOE–resin interface was exposed. After polishing, nanoindentation was performed on the region near the interface, and elastic modulus and hardness were plotted in the form of a color contour map. SEM was employed to observe the interface between composite resin and ZOE base.

Results

In the region close to the ZOE base, the elastic modulus and hardness of composite resin reduced to the values of 9.71 ± 0.54 and 0.51 ± 0.05 GPa, respectively. Eugenol from ZOE had detrimental effects on the composite resin only to a distance of less than 100 μm from the ZOE base.

Conclusion

Although eugenol suppresses polymerization slightly, by considering the biological advantages of ZOE, together with the results of the current investigation, ZOE may still be considered a suitable base material for composite resin. Bonding is essential for composite resin restorations over ZOE bases to avoid shrinkage detachment.     

Clinical study of indirect composite resin inlays in posterior stress-bearing cavities placed by dental students: results after 4 years

Objectives

This longitudinal randomized controlled clinical trial evaluated the longevity of composite resin inlays in single- or multi-surface cavities up to 4 years.

Methods

21 dental students placed 75 Artglass and 80 Charisma composite resin inlays in class I and II cavities in posterior teeth (89 adult patients) luted with dual-curing resin cements. Clinical evaluation was performed up to 4 years using modified USPHS criteria.

Results

87.2% of Artglass and 76.6% of Charisma inlays were assessed to be clinically excellent or acceptable. Up to the 4-year recall 5 Artglass and 11 Charisma inlays failed mainly because of postoperative symptoms, bulk fracture, and loss of marginal integrity. No significant differences between both composite resin materials could be detected at 4 years for all clinical criteria (Mann-Whitney U-test, p > 0.05). The comparison of restoration performance with time yielded a significant increase in marginal discolouration and postoperative symptoms (p < 0.05), deterioration of surface texture quality, marginal and restoration integrity (p < 0.05) for both inlay systems. However, the changes were mainly effects of scoring shifts from alfa to bravo. Small inlays compared to large inlays and premolar restorations compared to molar restorations showed significant better outcome for some of the tested clinical parameters for the Artglass inlays (p < 0.05). For Charisma inlays no such influences were revealed.

Conclusions

Clinical assessment of Artglass and Charisma composite resin inlays exhibited an annual failure rate of 3.2% and 5.9% that is within the range of published data. Within the limitations of this study indirect composite inlays are a competitive restorative procedure in stress-bearing preparations.     

Fracture strength and fracture patterns of root filled teeth restored with direct resin restorations

Objective

To compare fracture characteristics of root-filled teeth with variable cavity design and resin composite restoration.

Methods

80 extracted intact maxillary premolars were divided randomly into eight groups; (1) intact teeth; (2) unrestored MOD cavity; (3) unrestored MOD cavity plus endodontic access through the occlusal floor; (4) unrestored MOD plus endodontic access with axial walls removed; (5) MOD restored with resin composite; (6) MOD plus endodontic access, resin composite; (7) MOD plus extensive endodontic access, resin composite; (8) MOD plus extensive endodontic access, GIC core and resin composite. A ramped oblique load was applied to the buccal cusp in a servohydraulic testing machine. Fracture load and fracture patterns were recorded. Fracture loads were compared statistically using 1-way ANOVA, with Dunnett test for multiple comparisons.

Results

Unrestored teeth became progressively weaker with more extensive preparations. Endodontic access confined within the occlusal floor did not significantly affect strength compared to an MOD cavity. Loss of axial walls weakened teeth considerably [292 + 80 N vs 747 + 130 N for intact teeth]. Restoration increased the strength of prepared teeth particularly in teeth without axial walls. Teeth with a GIC core were not significantly weaker than intact teeth [560 + 167 N]. Failures were mostly adhesive at the buccal interface, with the fracture propagating from the buccal line angle of the occlusal floor (MOD and MOD plus access groups) or of the proximal box (axial wall removed).

Conclusions

Direct restorations increased fracture resistance of root filled teeth with extensive endodontic access. Both restored and unrestored teeth showed similar fracture patterns.