Composite Resin Restorations Research Articles

Two-year clinical evaluation of Class I composite resin restorations using three adhesive systems: A double-blind randomized clinical trial

Aim: The purpose of this randomized split-mouth clinical study was to assess the effect of three adhesive systems on the 2-year clinical success of Class I composite resin restorations. Methodology: In the treatment of the Class I carious lesions of 20 participants aged 18–24 years with at least three similar carious lesions, three adhesives—Clearfil SE Bond (CSE; Kuraray, Osaka, Japan), Single Bond 2 (SB2; 3M ESPE, St. Paul, MN, USA), and Tri-S Bond (TSB; Kuraray, Osaka, Japan)—and a Filtek Z550 nanohybrid composite resin (3M ESPE, St. Paul, MN, USA) were cured. The baseline and 2-year results of the restorations were assessed according to the World Dental Federation (FDI) and the United States Public Health Service (USPHS) criteria. The chi-square test was used to analyze the data obtained. Results: There was no loss of restoration in any group at 2 years. No significant differences were observed in any criteria (marginal staining, fracture retention, secondary caries, and postoperative sensitivity) evaluated except marginal adaptation, in accordance with FDI and USPHS criteria (p > 0.05). At 2 years, SB2 showed the best marginal adaptation, followed by CSE and TBS. There was a statistically significant difference between SB2 and TSB (p ˂ 0.05). Conclusion: All three adhesive systems can be used successfully in the restoration of Class I carious lesions. How to cite this article: Çakır Kılınç NN, Demirbuğa S. Two-year clinical evaluation of Class I composite resin restorations using three adhesive systems: A double-blind randomized clinical trial. Int Dent Res 2023;13(2):67-74. https://doi.org/10.5577/idr.2023.vol13.no2.4 Linguistic Revision: The English in this manuscript has been checked by at least two professional editors, both native speakers of English.

Shade selection for natural tooth color replication on porcelain laminate veneers

The final color of dental ceramics depends on different factors such as light source, substrate, and selected material (thickness, contour, and texture). Objective: To report a clinical case in which a predictable protocol is used to optimize the final color of porcelain laminate veneers. Case report: A male patient attended the dental clinic dissatisfied with the composite resin restorations made on his upper anterior teeth. After anamnesis and clinical examination, it was suggested that the resin restorations be replaced by laminated porcelain veneers. A diagnostic wax-up was performed. The mock[1]up was also used to evaluate the aesthetic length for replicating the details of the incisal edge and the shape and size of the embrasures. The shade was selected before composite resin removal to avoid dehydration of the dental substrate. A photograph was taken to guide the selection of colors in different thirds. After removing the restorations, another photograph was taken to evaluate the color of the substrate. The impression was taken with 000 retractor wire and addition silicone. The laminates were made with pressed ceramic and feldspathic porcelain veneers were subsequently applied by layering the layers of dentin, incisal edge and enamel based on the waxing diagnosis. After approval by the patient, a conventional cementation technique was performed. The occlusal adjustment was made with rubber polishing cups and the anterior and lateral guides were checked. Conclusion: The protocol recommended for successful selection of the color of a porcelain laminate relies on the combination of knowledge of concepts, resources such as shade guides, spectrophotometers, and photographs, and porcelain application and characterization techniques performed by the technician and luting techniques by the dentist.

The Effect of Salivary Contamination on the Shear Bond Strength of Seventh- and Eighth-generation Adhesive Systems.

To compare the effect of salivary contamination on the shear bond strength (SBS) of seventh- and eighth-generation adhesives. Specimens were randomly divided into group I and group II, subdivided into three subgroups of 11 samples. Subgroup IA-seventh-generation uncontaminated (control); adhesive; air-dried; light cured. Subgroup IB-seventh-generation adhesive; saliva application, air-dried; light cured. Subgroup IC-seventh-generation adhesive; saliva application, air-dried, reapplication of adhesive, air-dried, light cured. Subgroup IIA- eighth-generation uncontaminated (control); adhesive, air-dried; light cured. Subgroup IIB- eighth-generation adhesive; saliva application, air-dried; light cured. Subgroup IIC-eighth-generation adhesive, saliva application, air-dried, reapplication of adhesive, air-dried; light cured. Following bonding procedure, composite resin restoration was done and subjected to SBS analysis. Mean SBS of eighth-generation adhesive was higher compared to seventh with and without saliva contamination. Reduction of SBS in seventh- and eighth-generation after saliva contamination was regained by reapplication of adhesive, which was less compared to the control [statistically significant (p < 0.05) for seventh and statistically not significant for eighth-generations]. The eighth-generation adhesives show better SBS with and without saliva contamination and reapplication of eighth-generation adhesives significantly improved the SBS close to the control. Single-step self-etch adhesives are the adhesives which are currently used for bonding composite restorations to dentin. The adhesive bond strength can be adversely affected by moisture contamination, especially by saliva, which can lead to failure of restoration. So, it is imperative to study a material which gives better bond strength and is less affected by salivary contamination and effect of decontamination to regain the bond strength. The study concluded that eighth-generation adhesives showed higher mean SBS with and without saliva contamination and reapplication of eighth-generation adhesives significantly improved the bond strength close to the control group. Mohan MC, Geetha P, Soman D, et al. The Effect of Salivary Contamination on the Shear Bond Strength of Seventh- and Eighth-generation Adhesive Systems. Int J Clin Pediatr Dent 2023;16(S-1):S63-S66.

Direct or indirect composite for restoring permanent first molars affected by Molar Incisor Hypomineralisation (MIH): a randomized clinical controlled trial

AimThis study was undertaken to compare direct composite resin restorations (DCRR) and indirect composite resin restorations (ICRR) for treating permanent first molars affected by MIH in terms of clinical performance.Materials and methodsThis was a controlled, randomized, clinical split-mouth study. The studied sample consisted of 40 asymptomatic first permanent hypomineralised mandibular molars in 20 children aged between 7–11 years, these cases were divided randomly into two groups: Group 1 (experimental): 20 first permanent mandibular molars were restored with ICRR, and Group 2 (control): 20 first permanent mandibular molars that were restored with DCRR. The cavity was prepared using a diamond bur on a high-speed handpiece, and the prepared cavity was wiped with cotton moistened with sodium hypochlorite. The composite was applied directly with a total-etch bonding system. In the ICRR group, an impression for the prepared cavity was taken using a silicon-based material, and the restoration was adhesive with self-adhesive resin cement. The child’s satisfaction with each of the two application techniques was assessed through the scale FACES. Restorations were evaluated during follow-up periods (3, 6, and 12 months) according to Modified USHPH criteria.ResultsThe clinical success rate was 90% in the ICRR group versus 85% in the DCRR group after 12 months of follow-up without statistically significant differences (P = 0.218). Children were significantly more satisfied (P = 0.0351) with ICRR than DCRR.ConclusionsBoth DCRR and ICRR can be considered effective restorations with acceptable clinical performance in the restoration of hypomineralised first permanent molars with an advantage of ICRR in terms of child acceptance of the restoration application technique.

Selective Removal to Soft Dentine versus Full Pulpotomy for Management of Proximal Deep Carious Lesions: A Randomized Controlled Non-Inferiority Trial

The management of the deep carious lesion with reversible pulpitis is a dilemma for the dentist. The current study compared selective removal to soft dentine (SRSD) and full pulpotomy (FP) for treating proximal deep carious lesions in teeth with reversible pulpitis. Visual-tactile examination and bitewing radiographs were used to determine the depth of carious lesion, and American Association of Endodontists recommendations were used to formulate pulp diagnosis. Sixty mandibular molar teeth from healthy patients between the ages of 16–35 years and a diagnosis of proximal deep carious lesion with reversible pulpitis were included. Teeth were randomly allocated to two study groups. SRSD group (n = 30): soft dentine was preserved over the pulpal aspect. A hard-setting calcium hydroxide cement liner and resin-modified glass ionomer cement base were applied over the remaining soft carious dentine. FP group (n = 30): complete caries removal followed by mineral trioxide aggregate FP was performed. The teeth in both groups were restored with composite resin restoration. The established criteria for outcome assessment of SRSD and pulpotomy were used. Accordingly, only asymptomatic teeth with no radiological evidence of periapical rarefaction were considered successful at the 12-month follow-up. Two-sample t test, Pearson χ² test/Fisher’s exact test, and percentage agreement were used for statistical evaluation. According to the per-protocol analysis, the success rate of both SRSD and FP treatment was 95.45% and 95.65%, respectively, and the actual difference between the two treatments was 1% (95% CI: [−10, 9]). The data suggests that both treatments (SRSD and FP) appear to have a good success rate (>95%) when used to manage permanent mandibular molar teeth with proximal deep carious lesion and reversible pulpitis. As SRSD is a noninvasive procedure, it should be favored over FP in these instances.

The Effect of Bonding Surface Design on Shear Bond Strength of 3D-Printed Orthodontic Attachments.

This study compared the shear bond strength (SBS) of four innovative designs of the bonding surface of 3D-printed orthodontic attachments with conventional mesh design. In this in vitro study, the bonding surface design in different groups was as follows: Group 1, flat surface without any feature as a negative control; Group 2, concentric circles with no cuts; Group 3, concentric circles with 16 radial cuts; Group 4, concentric circles with 32 radial cuts; Group 5, small cones with a flat end and rounded edges; Group 6, mesh-based commercially available metal brackets of the maxillary central incisor (standard edgewise, Dentaurum®) as a positive control (n = 20). In Groups 1-5, attachments were designed with SolidWorks® Software and printed with a 2K DLP-LCD printer with hard tough resin (eSun®). All the samples were bonded to the restorative composite resin (Solafil®) surfaces with orthodontic composite resin (CuRAY-ECLIPSE®). The samples were examined for SBS with a universal testing machine after thermocycling (1,000 cycles of 5‒55°C). Data were analyzed with Shapiro-Wilk, one-way ANOVA, and Bonferroni tests. The statistical significance level was set at 0.05. The mean SBS was significantly different between all the groups (P < 0.001) except for Groups 2 and 5 (P = 1.00) and Groups 2 and 6 (P = 1.00). Group 4 had the highest mean of SBS. The bonding surface design significantly influenced the SBS of orthodontic attachments. The concentric circles with 32 cuts had higher bond strength than other designs and can be suggested as a new bonding surface design for orthodontic attachments.

Impact of matrix systems on proximal contact tightness and surface geometry in class II direct composite restoration in-vitro

BackgroundPoor contact tightness and contour in class II composite restorations are significant problems in clinical practice. They affect occlusal stability and periodontal health. The aim of this study was to evaluate proximal contact tightness and contour established after completing class II direct composite restorations using two pre-contoured matrix systems.MethodsStandardized mesio-occlusal cavities were prepared in twenty typodont lower right first permanent molar teeth. Prepared teeth were randomly divided into two groups according to matrix system: Group 1, Sectional matrix system with a separation ring (Palodent V3); and Group 2, Circumferential matrix system with integrated tightener (Palodent 360). Contact tightness was evaluated using universal testing machine. Area, depth and curvature radius of proximal surface concavity in the restoration were evaluated using contact stylus profilometer. T-test was used for comparison between groups.ResultsSectional matrix showed higher contact tightness than circumferential matrix system. The results of proximal surface concavity in the restoration showed significantly higher area and depth of concavity with lower radius of curvature in circumferential matrix compared to sectional matrix.ConclusionsThe use of separation ring with sectional matrix provides superior contact tightness compared to circumferential matrix. However, both matrix systems presented some deficiency regarding proximal contour of direct class II resin composite restoration.

One Step Polishing System Difference on Bulk-Fill Composite Resin Microhardness, Surface Roughness, and Color Stability

Background: The polishing procedure was an important step in composite resin restoration as it reduces restoration surface roughness. Smooth and well-polished restoration surfaces can increase microhardness and minimize discoloration on the tooth surface. The study aims to examine the differences of one-step polishing systems on surface roughness, microhardness, and color stability of bulk-fill composite resin.&#x0D; Method: The samples were bulk-fill composite resin moulded with 4 mm of diameter and thickness (n=30) for microhardness (n=15) and surface roughness (n=15) test and moulded with 6 mm of diameter and 4 mm of thickness for color stability (n=15) test. The samples were divided into three groups consisting of 5 samples for each variable and were polished using PoGo, OptraPol, and OneGloss. Color stability test samples were immersed in tea solution for 7 days. Color stability measurement was done by comparing the results of color measurements using a spectrophotometer before and after immersion. Microhardness was tested using Vickers Microhardness Tester, while surface roughness was tested using the Stylus Profilometer Fowler Surfcorder SE1700.&#x0D; Result: The data analysis showed that PoGo produced the smoothest surface roughness significantly (p=0.006), the highest microhardness significantly (p=0.002), and the lowest color change significantly (p = 0.027)&#x0D; Conclusion: PoGo produced lowest surface roughness and color change, and highest microhardness compare with OptraPol and OneGloss.

Formulation, Configuration, and Physical Properties of Dental Composite Resin Containing a Novel 2π + 2π Photodimerized Crosslinker - Cinnamyl Methacrylate: An In Vitro Research.

To formulate and characterize the chemical structure of a new dental composite with photodimerized cinnamyl methacrylate (PD-CMA) photo-crosslinking comonomer and to evaluate the monomer-to-polymer conversion (MPC) and glass transition temperature (Tg) of the new composite copolymers. CMA was PD by ultraviolet C-type (UVC) irradiation. The research groups were a control group C0 without PD-CMA and two trial groups: E10 (10 wt. % PD-CMA substituted in the base comonomers (B) and diluent (D) mixture); E20 (20 wt.% PD-CMA completely replacing the diluent (D) monomer). Infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopies were employed for ascertaining copolymerization (CP). The surface features and composition of the copolymers were explained by field-emission scanning electron microscopy (FESEM) and energy dispersive X-ray (EDX) spectroscopy, respectively. The MPC and Tg of the copolymers were assessed using FTIR and differential scanning calorimetry, respectively. Statistical tests were used to compare the groups. The configuration of the new copolymers P (BD-Co-CMA) and P(B-Co-CMA) was confirmed. The MPC% and T g of the copolymers were better than the control. PD-CMA at 20 wt. % in the P (B-Co-CMA) copolymer exhibited the highest MPC% and Tg. The incorporation of PD-CMA in the composite resin resulted in new P (BD-Co-CMA) and P (B-Co-CMA) copolymers with improved MPC% and Tg. The substitution with PD-CMA offset the shortcomings of the conventional BD comonomers concerning the mechanical properties and biocompatibility of the restorative composite resin. This might ameliorate the restorations in vivo longevity and serviceability.

Perception of oral health related quality of life and orofacial aesthetics following restorative treatment of tooth wear: A five-year follow-up

ObjectivesNon-carious tooth wear often has a multifactorial etiology and may lead to functional or aesthetically related problems. The most common complaints associated with tooth wear are dissatisfaction with dental appearance and a negative impact on the experienced Oral Health Related Quality of Life (OHRQoL). The aim of this study was to investigate the change in OHRQoL and the perception of aesthetics, following restorative treatment of moderate to severe tooth wear patients, with a five-year follow-up. MethodsAn explorative study, based on prospective data, was performed. OHRQoL and the perception of aesthetics were measured with the OHIP-NL and OES-NL. These questionnaires were completed before treatment, one month after treatment, and at 1-, 3- and 5-years post-treatment. Treatment involved full mouth reconstruction with composite resin restorations. The data was analysed as repeated measures by using a linear mixed-effects model. ResultsOne hundred and twenty-three tooth wear patients that received restorative rehabilitation were included (97 males, 26 females, 37.5 ± 8.8 years-old). Data showed a statistically significant increase in both experienced OHRQoL and orofacial appearance after restorative treatment. The OHIP-scores remained stable over time, while the OES-scores slightly decreased during the years after treatment. Regarding the seven domains of the OHIP, the largest difference in OHIP-score was found in the domain of ‘Psychological Discomfort’. The mean overall OHIP-score was 1.8 at baseline and 1.3 at the 5-years recall. The mean OES score increased from 41.8 at baseline to 66.1 at the 5-years follow-up. ConclusionsTooth wear patients reported significant improvements in their OHRQoL and their perception of orofacial aesthetics after restorative treatment. This increase remained at least five years post-treatment. Clinical SignificanceThe clinical impact of restorative treatment for tooth wear patients is considerable. This paper emphasizes the need to include a discussion of the patient related outcome measures when planning care.

Machine Learning Analysis of Microtensile Bond Strength of Dental Adhesives.

Dental adhesives provide retention to composite fillings in dental restorations. Microtensile bond strength (µTBS) test is the most used laboratory test to evaluate bonding performance of dental adhesives. The traditional approach for developing dental adhesives involves repetitive laboratory measurements, which consumes enormous time and resources. Machine learning (ML) is a promising tool for accelerating this process. This study aimed to develop ML models to predict the µTBS of dental adhesives using their chemical features and to identify important contributing factors for µTBS. Specifically, the chemical composition and µTBS information of 81 dental adhesives were collected from the manufacturers and the literature. The average µTBS value of each adhesive was labeled as either 0 (if <36 MPa) or 1 (if ≥36 MPa) to denote the low and high µTBS classes. The initial 9-feature data set comprised pH, HEMA, BisGMA, UDMA, MDP, PENTA, filler, fluoride, and organic solvent (OS) as input features. Nine ML algorithms, including logistic regression, k-nearest neighbor, support vector machine, decision trees and tree-based ensembles, and multilayer perceptron, were implemented for model development. Feature importance analysis identified MDP, pH, OS, and HEMA as the top 4 contributing features, which were used to construct a 4-feature data set. Grid search with stratified 10-fold cross-validation (CV) was employed for hyperparameter tunning and model performance evaluation using 2 metrics, the area under the receiver operating characteristic curve (AUC) and accuracy. The 4-feature data set generated slightly better performance than the 9-feature data set, with the highest AUC score of 0.90 and accuracy of 0.81 based on stratified CV. In conclusion, ML is an effective tool for predicting dental adhesives with low and high µTBS values and for identifying important chemical features contributing to the µTBS. The ML-based data-driven approach has great potential to accelerate the discovery of new dental adhesives and other dental materials.

Effects of Different Toothpastes on the Nanomechanical Properties and Chemical Composition of Resin-Modified Glass Ionomer Cement and Composite Resin Restorations.

This study evaluates the effects of different toothpastes on the nanohardness and chemical compositions of restorative materials and dental surfaces. Bovine enamel (n = 72) and dentin (n = 72) blocks were obtained and restored using RMGIC (n = 36) or CR (n = 36) to create the following surfaces: dentin adjacent to RMGIC (DRMGIC), enamel adjacent to RMGIC (ERMGIC), dentin adjacent to CR (DCR), and enamel adjacent to CR (ECR). After restoration, one hemiface of each specimen was coated with an acid-resistant varnish to facilitate the creation of control (C) and eroded (E) sides; the latter were achieved by erosion-abrasion cycles as follows: erosion with 1% citric acid: 5 days, four times for 2 min each day; 1% citric acid/abrasion, two times for 15 s, followed by immersion in a toothpaste slurry for 2 min. Toothpastes without fluoride (WF; n = 12), with sodium fluoride (NaF; n = 12), and with stannous fluoride (SnF2; n = 12) were used for RMGIC or CR. The specimens were analyzed for nanohardness (H), and chemical composition using energy-dispersive X-ray spectroscopy and Raman microscopy. The data were statistically analyzed using two-way repeated measures ANOVA and Tukey's test (α = 0.05). Lower H values were obtained with NaF for DRMGIC-C, with a statistically significant difference from the H value obtained with WF (p < 0.05). The calcium and phosphorus concentrations in DCR-E were significantly lower with WF than with the other types of toothpaste (p < 0.05). Fluoride-containing toothpastes are capable of preserving the main chemical components of the dentin adjacent to the restorative materials under erosive-abrasive conditions.

Is surface roughness of direct resin composite restorations material and polisher-dependent? A systematic review.

Direct resin composite bonding offers a highly esthetic, minimally invasive option for the treatment of anterior teeth however the challenge to improve their longevity remains. Direct resin composite restorations are limited by the risk of staining which may be influenced by the final surface roughness (Ra) of composite achieved. The purpose of this review is to investigate, using a systematic approach, whether the final surface roughness of anterior composite restorations is affected by the interaction between resin composite and polishing systems. The review was conducted by 3 independent reviewers and included articles published up to January 21, 2021. Three electronic databases were searched: Medline, Embase, and Web of Science. Studies assessing a quantitative effect of polishing methods on the Ra of direct composite resin materials published after the year 2000 and restricted to the English language were included. The database search for the effect of polishing systems on composite materials retrieved 125 eligible studies. Twelve duplicate records were removed. The resulting records were screened using title and abstract leading to 38 reports which were sought for retrieval. Application of eligibility criteria led to 11 studies included in the review. Hand searching of these studies yielded no additional papers. There is insufficient evidence to determine whether combination of composite and polisher influences final Ra. More research is required to determine if there is an optimum combination of polisher and composite. Polishing should be completed following planned finishing procedures. The approximation to the final surface and which finishing burs to use, if any, should be considered when planning a restoration. Durafill VS predictably achieves an acceptable Ra by different polishers.

The clinical performance of bulk-fill versus the incremental layered application of direct resin composite restorations: a systematic review

ObjectivesTo systematically review the scientific evidence comparing the clinical effectiveness of bulk-fill versus incrementally layered conventional resin composites and to evaluate if one method offers clear merits with specific clinical outcomes.Materials and methodsUsing relevant mesh terms and pre-established eligibility criteria in PubMed, Embase, Scopus and Web of Science, a thorough scientific search was conducted with an end-date of 30.04.2023. Randomized controlled clinical trials that involved the direct comparison of Class I and Class II resin composite restorations applied using incremental layering techniques versus bulk-filled in permanent teeth with an observation period of at least six months were considered. To evaluate the bias risk of the finalized records, a revised version of the Cochrane risk-of-bias tool for randomized trials was implemented.ResultsOut of the 1445 records determined, 18 eligible reports were chosen for qualitative analysis. Data obtained was categorized as per, the cavity design, the intervention, the comparator(s), the methods of success/failure assessment, the outcomes, and follow-up. Two studies demonstrated an overall low-risk of bias, fourteen studies raised some concerns, and two studies exhibited high-risk.ConclusionBulk filled resin composite restorations demonstrated clinical outcomes similar to those of incrementally layered resin composite restorations within a review interval of 6 months to 10 years.

Multiple traumatised upper incisors in children treated by autotransplantation and orthodontics — a 4-year follow-up

Abstract Objective To present two young patients treated by the autotransplantation of developing premolars and subsequent orthodontic space closure and to report a 4-year follow-up result. Case and method Two 11-year-old patients suffered traumatic anterior dental injuries resulting in ankylosis and subsequent extractions. After consulting the multidisciplinary team, the developing lower second permanent premolars with immature root apices were chosen to replace the injured upper incisors using autotransplantation. Results Six months after autotransplantation, orthodontic treatment was initiated to close the upper arch spaces, correct the dental midline deviation and to camouflage the transplanted teeth. Normal overbite and overjet were achieved and Class I canine and molar relationships were obtained. After the removal of the orthodontic appliances, composite resin restorations were placed on the upper anterior teeth. During a 4-year follow-up, the pulp vitality of the transplanted teeth was normal with no periodontal nor pathological findings. Pulp canal obliteration with adequate apical length was observed in all the teeth. Conclusion In children presenting with upper incisors lost to trauma, autotransplantation of developing lower premolars into the upper anterior region followed by orthodontic space closure can be a viable treatment modality producing satisfactory aesthetics and function.

Ultrathin Partial Ceramic Veneers in the Esthetic Zone with Tooth Whitening: A 5-year Case Report.

This case report describes a minimally invasive approach with tooth whitening and partial ceramic veneers in the esthetic zone with a 5-year follow-up. The patient was initially concerned about the tooth color and previous direct resin composite restorations that chipped on the incisal edges of both maxillary central incisors. Tooth whitening and partial veneers for both central incisors were recommended after clinical evaluation. Two sessions of in-office tooth whitening, first with 35% hydrogen peroxide and later with 10% carbamide peroxide from first premolar to first premolar, were provided. Minimal tooth preparation that only removed the fractured composite restorations was performed followed by placement of feldspathic porcelain ultrathin partial ceramic veneers for both central incisors. We emphasize the benefits of minimal tooth preparation paired with partial ceramic veneers and the importance of masking discolored tooth structure with such thin veneers, including potential tooth whitening. Overall, we demonstrate a well-planned and executed restorative procedure combining tooth whitening and ultrathin partial ceramic veneers to achieve desired results in the esthetic zone that remained successful for five years.

Investigating the impact of flowable composite liner on the fracture strength and microleakage of large composite resin restorations of primary anterior teeth.

To investigate the effect of pre-cured and co-cured flowable composite liner on fracture strength and microleakage of primary anterior teeth with extended composite resin restorations. In the current in vitro experimental study, the crowns of 54 extracted primary canine teeth were cut 1mm above the CEJ, and a pulpectomy procedure was performed. The samples were randomly divided into three groups to restore the coronal part up to 4mm above the CEJ. In group 1, the samples were built up with Filtek Z250 packable composite resin. In group 2 (pre-cure), first, 1mm of Filtek Z350 XT flowable liner was applied to the sample, and after curing, the restoration process continued using packable composite resin. In group 3 (co-cure), the flowable composite liner was cured while the first layer of packable composite resin was applied; then, the same restorative procedure similar to the other groups was followed. The samples' cross-sectional area in the fracture strength test was calculated by AutoCAD software. Subsequently, the samples were subjected to a force in a universal testing machine. The samples related to the microleakage experiment were cut vertically, and then, the dye penetration percentage (10% methylene blue) was measured under a stereomicroscope. ANOVA was used to analyze the data. Mean fracture strength in group 2 was significantly higher than in group 1 (P = 0.016). The microleakage mean in group 3 was significantly lower than in groups 1 (P = 0.000) and 2 (P = 0.026). The flowable composite liner and its relevant separate curing increased the fracture strength of composite resin restorations. However, less microleakage was reported in the group where the liner was applied as a co-cure.

Clinical Evaluation of Reasons for Immediate Composite Restoration Failure Placed by Dental Students: A Cross-sectional Study in Jordan

Objective: The present study aims to investigate the reasons for the immediate failure of direct anterior and posterior resin composite restorations placed by dental students. Methods: A cross-sectional study on resin composite restorations placed by fourth- and fifth-year dental students (n=436). Variables included in the study were; the operative field isolation method, the time needed to complete the restoration after cavity preparation to polishing and finishing, and the plaque index of the patient. Restoration class distribution according to the type of tooth and cavity classification was examined and recorded. Restorations were clinically evaluated immediately after placement. It involved the assessment of the restoration’s mobility, marginal discoloration, and lack of anatomy. Results: A total of 233 direct anterior and posterior resin composite restorations which were placed by 127 students were diagnosed as failed restorations. The mode of failure was distributed as mobility/debonding (61.80%), marginal discoloration (29.18%), and lack of anatomy (9.02%). Cl III restorations demonstrated the highest failure on tooth type and cavity classification (30%), followed by Cl II restorations in molars (18.45%). Failure-associated factors were proper restoration manipulation, field isolation, and patients’ plaque index. Conclusion: In the current study, the most frequent reason for the immediate failure of resin composite restorations was the quick application of the restoration either as the only associated factor or coupled with other failure-associated factors. Failure to maintain proper field isolation and the poor oral hygiene of the patient were the other two failure-associated factors.

Influence of Storing Composite Filling Materials in a Low-pH Artificial Saliva on Their Mechanical Properties-An In Vitro Study.

Restorative composites are subjected to various influences in the oral cavity environment, such as high or low temperatures, the mechanical force generated during mastication, colonization of various microorganisms, and low pH, which may result from ingested food and the influence of microbial flora. This study aimed to investigate the effect of a recently developed commercial artificial saliva (pH = 4, highly acidic) on 17 commercially available restorative materials. After polymerization, the samples were stored in an artificial solution for 3 and 60 days and subjected to crushing resistance and flexural strength tests. The surface additions of the materials were examined in terms of the shapes and sizes of the fillers and elemental composition. When stored in an acidic environment, the resistance of the composite materials was reduced by 2-12%. Larger compressive and flexural strength resistance values were observed for composites that could be bonded to microfilled materials (invented before 2000). This may result from the filler structure taking an irregular form, which results in a faster hydrolysis of silane bonds. All composite materials meet the standard requirements when stored for a long period in an acidic environment. However, storage of the materials in an acid environment has a destructive impact on the materials' properties.

Fracture load and failure mode of semi-direct resin composite occlusal veneers: Influence of design and mechanical cycling

AimsTo evaluate the influence of the type of preparation and mechanical cycling on the fracture load and failure mode of semi-direct posterior resin composite restorations. MethodsIn total, 70 healthy third molars were used; 10 belonging to the control group (C - unprepared teeth) and 60 teeth prepared and restored with nanoparticle resin composite, divided into 3 groups (n = 20): O - exclusively occlusal preparation (Table Top); OV - occlusal preparation with buccal extension (Veneerlay); OVP - Occlusal preparation with chamfer on the proximal and buccal-lingual/palatal surfaces (Overlay). The preparations were performed with diamond burs with a thickness of 1 mm. The restorations were made with nanoparticulate resin composite (Filtek Z350 XT) and subsequently received additional polymerization (thermoprocessing). Cementation was performed with the use of universal adhesive system (Single Bond Universal) on dental substrate and dual resin cement (RelyX ARC). Half of the teeth in each group (n = 10) were submitted to mechanical cycling, simulating 6 months of clinical service (5 × 105 fatigue cycles), under dynamic loading of 130 N, at a frequency of 2Hz. Fracture load tests were performed in a universal testing machine with a 200 kgf load cell. Failure mode was classified using scores. Generalized linear models and Fisher Exact tests were applied to the data (significance level of 5%). ResultsThere were no significant differences between the types of preparation (p = 0.9435), or relative to cycling (p = 0.3764). The Fisher Exact Test showed a significant association between the groups and the type of failure (p = 0.0006), with preparations O (with cycling) and OVP (with and without cycling) exhibiting most failures with restoration fractures without involvement of the dental remnant. ConclusionsSemi-direct restorations showed resistance to fracture load similar to that of healthy teeth and were capable of withstanding functional masticatory loads. The type of preparation influenced the failure mode of teeth. The Table Top and Overlay types of preparations were those had fewer catastrophic failures, suggesting that since they are more conservative preparations, they made it possible for the tooth to receive a new restorative procedure in the future in cases of failures.