CLINICAL CASE REPORT

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CLINICAL CASE REPORT: WOULD THE BULK FILL TECHNIQUE BE ABLE TO REPLACE THE LAYERING TECHNIQUE IN POSTERIOR RESTORATIONS?
TRIVELLATO, F. G.; RESENDE, A.M.; PAZINATTO, R.B.; BAROUDI, K. SALVIO, L. A. 
ABSTRACT 
Resin composites emerged in Dentistry as innovative materials in regarding performing esthetic and functional restorations. However, the clinical consequences caused by polymerization shrinkage and limited depth of cure of these materials require the use of a layering technique, based on the insertion of small increments at each time. This technique demands time, clinical skills and also involves some risks, such as contamination between layers and inadequate polymerization. In this context, the bulk fill composites emerge, in regular and flow viscosities, proposing the simplification of clinical protocol with insertion technique of an only increment up to 4 mm thickness. Thus, the aim of this study was to revise the literature about bulk fill resin composites and perform a clinical case study to demonstrate the techniques proposed on the insertion of these materials. Two different techniques were proposed to restore Class I cavities with a 4 mm depth in two mandibular molars (elements 37 and 46) that belonged to the same patient. The 37 element was restored with the Tetric N-Ceram Bulk Fill (Ivoclar Vivadent, Schaan, Liechtenstein) composite in an only increment, while the 46 element was restored with the Surefil SDR Flow (Dentsply Sirona, York, PA, USA) composite and the convencional resin composite Tetric N-Ceram (Ivoclar Vivadent, Schaan, Liechtenstein). After the conclusion of the restorations, they were assessed based on the USPHS criteria for direct clinical evaluation. Therefore, based on the revised literature and study of the clinical case, it was established that the bulk fill techniques are able to replace the incremental technique in posterior restorations, as long as there is a careful selection in regarding choice of materials and the adequate indications and clinical protocols are respected. 
KEY WORDS: Composite resins. Permanent Dental Restoration. Dental Materials.
INTRODUCTION
	The success of a resin composite restoration depends substantially on its adaptation in the cavity walls and on its union to dental substrates (RENGO et al., 2015). Thereby, manufacturers seek alternatives and strategies to increasingly improve its physical and mechanical properties (MOORTHY et al., 2012). It is known that the polymerization shrinkage of the resin composite is inherent in the material and of crucial importance regards adequate marginal integrity and restoration durability. The polymerization kinetics, as well as filler loading and organic matrix contents define the viscoelastic properties and degree of conversion of resin composites. Furthermore, the geometric preparation of the cavity has direct influence on the shrinkage stress of resin composites. Cavities with high cavity configuration factor (factor C) have higher chances of polymerization shrinkage stress (RENGO et al., 2015). Thus, different strategies to minimize shrinkage stresses have been studied and improved continuously; such as: progressive polymerization methods, use of resin composites with lower elastic modulus (flow) as foundation to absorb part of the shrinkage stresses and the insertion of small increments of resin at a time aiming to reduce factor C (KIM et al., 2015; TEKIN et al., 2017). 
	During the restoration technique, it is recommended that the resin composite increment do not exceed 2mm in thickness, since this material has limited polymerization depth (VAN DIJKEN e PALLESEN, 2015). While the surface layer might be properly cured, the deeper layers might not be which may cause cytotoxic damages to the pulp (FURNESS et al., 2014; GONÇALVES et al, 2018). The buildup layering technique is complex and demands technical ability and clinical time. It also may come with technical risks, such as air incorporation, contamination between layers and adhesion failure in larger cavities (ORLOWSKI, TARCZYDLO and CHALAS, 2014). 
	Aiming to overcome those disadvantages, bulk fill composites were created: a new generation of resin composites that aims to accelerate and facilitate clinical protocol of posterior cavities restorations. This kind of material can be inserted in an only increment up to 4mm thickness (ILIE e STARK, 2014) in cavities with high factor C, without causing polymerization shrinkage stresses and reaching adequate degree of conversion (FURNESS et al., 2014).
	The bulk fill restoration technique can be very clinically attractive, but its internal adaptation might contain a few gaps which would jeopardize restoration longevity. Based on this disadvantage, manufacturers created a new version of bulk fill composite called bulk fill flow, which has lower viscosity and allows a better internal adaptation in narrow and sinuous cavities (ILIE et al., 2014).
	Bulk fill resin composites are, generally, more translucent compared to conventional resin composites, since the increased translucency is one of the strategies used to achieve higher polymerization depth in thicker layers (KIM et al., 2015). This change in material composition reduces dispersion and increases light penetration throughout the increment (VAN DIJKEN and PALLESEN, 2015; MEEREIS et al., 2018). Besides translucency, the increase of depth of cure in bulk fill composites is also related to the incorporation of modified monomers and different photointiation systems to the material compositions. For example, the manufacturer of Tetric-N-Ceram Bulk Fill (Ivoclar Vivadent) claims that, although this composite holds a traditional initiator system based on camphorquinone and amine, it was added to its composition a “polymerization booster” called Ivocerin®, which assists in reducing polymerization shrinkage and increasing the depth of cure in thicker layers (KIM et al., 2015). 
	The bulk fill technology presents several benefits such as: lower chance of gap formation throughout the restoration, convenience and clinical time decrease in bulk technique compared to the conventional buildup technique and standardized polymerization protocol for the whole restoration. However, there still are a variety of doubts and questions regarding durability and efficiency of these composites, since their clinical success can only be established after their long-term use and with additional studies and publications regard their clinical behavior (DIDEM, GÖZDE and NURHAN, 2014).
	Therefore, the aim of this study is to demonstrate, through a clinical case study, the advantages and disadvantages of the different techniques used to perform posterior restorations with resin composites, comparing the buildup layering technique of conventional resin composites to the bulk technique of bulk fill composites of high and low viscosity. 
	The present study aims to demonstrate, through a clinical case study, the advantages and disadvantages of the different techniques used to perform posterior restorations with resin composites, comparing the buildup layering technique of conventional resin composites to the bulk technique of bulk fill composites of high and low viscosity.
	The null hypothesis tested is that bulk fill techniques present more benefits in regarding simplification of clinical protocol, lower chances of contamination and higher quality of polymerization compared to the buildup technique of conventional resin composites.
CLINICAL CASE REPORT
	Patient M. A. O. F., male, 21 years old, attended the Dental Urgency Clinic of the Dental School of the Federal University of Juiz de Fora, Brazil, for the examination of a local gingival inflammation. The patient’s current and past medical history were taken, and no relevant facts were noted. During intraoral clinical examination, subgingival calculus was found on the area affected by inflammation and, additionally, deficient class I restorations were found on elements 36, 37 and 46 plus fissure pigmentation on element47 (Pictures 1, 4 and 5). Periapical radiographs were taken to confirm diagnoses of carious lesions and marginal microleakage through the presence of radiolucent areas on the occlusal surface (Pictures 2 and 3). Some of the microleakage lesions were only clinically detected due to overlap of structures and small depth of pigmentation. The immediate treatment chosen to treat the patient’s main complaint was manual scraping of the subgingival calculus with curettes and prescription of 0,12% clorhexidine digluconate as a mouth wash. Afterwards, the patient was referred to the Reabilitation Extension Project for further evaluation of the deficient restorations to be replaced. 
	During evaluation on the Reabilitation Project, it was found that the restorations to be replaced on elements 36, 37 and 46 were the same in regards Black’s classification (class I) and presented similar features regarding depth and buccolingual extension, enabling a reliable and standardized comparison method between restoration techniques and restorative materials. As for element 47, the periapical radiograph did not show a deep carious lesion, defining its indication for an invasive sealant in flow resin composite. Therefore, after approval by the Human Research Ethics Committee of the Federal University of Juiz de Fora (opinion nº 2943893), the clinical case study was proceeded. 
	The study proposed the use of the traditional buildup layering technique with a nanohybrid resin composite (Tetric N-Ceram, Ivoclar Vivadent, Liechtenstein) on of the elements; on the second element, the use of the bulk technique with a high viscosity bulk fill composite (Tetric N-Ceram Bulk Fill, Ivoclar Vivadent, Liechtenstein) and on the last element, the use of a low viscosity bulk fill composite (Surefil SDR Flow, Dentsply Caulk, Milford, DE, USA) as base for the restoration, followed by an occlusal coverage made out of conventional resin composite. 
Restorative Procedures
Element 36 - For element 36, initially restored in amalgam, it was proposed the traditional build up layering technique with Tetric N-Ceram. After local anesthesia of the inferior alveolar nerve with lidocaine and epinephrine (Alphacaine 2%, 1:100.000, Nova DRL, Rio de Janeiro, RJ, Brazil), the amalgam was removed with sphere diamond burr nº 1014 (KG Sorensen, Agerskov, Denmark) under refrigeration in high speed rotation. During the amalgam removal, it was noted the presence of secondary caries on the pulp surface of the cavity. Due to the high extension of the lesion and the pulp chamber’s high volume, it was established the risk of pulp exposure and a conservative and atraumatic removal of the lesion was opted, as well as an expectant treatment. Calcium hydroxide cement HydCal (Technew Ind., Rio de Janeiro, RJ, Brazil) was applied to the remaining of the lesion and a temporary restoration was made out of glass ionomer cement Vidrion R (SS White, New Jersey, NY, USA) applied with Centrix syringe. The approximate time of proservation was defined as 40 days. 
Element 37 - For element 37, it was proposed the bulk technique with Tetric N-Ceram Bulk Fill, color IVA. After local anesthesia of the inferior alveolar nerve with lidocaine and epinephrine (Alphacaine 2%), the deficient restoration in resin composite was removed with a conical trunk diamond burr nº 2136 (KG Sorensen) under refrigeration in high speed rotation. With the same burr, the contour and convenience shapes were defined, as conservatively as possible (Picture 6). After full removal of the restoration and compromised dental tissue, dental isolation was performed, extended only up to element 34 due to the presence of orthodontic retainer (Picture 7). The cavity depth was measured with a millimeter probe, which indicated a depth of 4mm (Picture 8). The cavity hybridization was performed with universal self-etching adhesive system (Single Bond Universal, 3M ESPE, São Paulo, SP, Brazil), starting with selective conditioning of the enamel restricted to the cavosurface angle with 37% phosphoric acid (Alpha Etch, Nova DFL, Rio de Janeiro, RJ, Brazil) for 30 seconds. Next, the acid was abundantly rinsed for 30 seconds with air-water jet and the cavity was dried with air jet. Next, a drop of the universal adhesive was actively applied in the whole cavity for 20 seconds (Picture 10), followed by a light air jet for 5 seconds and cured for 10 seconds with LED light photopolymerizer (Bluephase, Ivoclar Vivadent, Schaan, Liechtenstein). After hybridization, the cavity filling was performed in an only increment, inserted with burnisher nº 22 (Picture 11). To establish an adequate occlusal anatomy sculpture, an explorer tool nº 5 was used (Picture 12). The increment was cured for 20 seconds. Additionally, characterization colors (Empress Direct Color, Ivoclar Vivadent, Schaan, Liechtenstein) were applied on the depth of the main grooves (color ochre) and on cusps ridges (color white). Afterwards, the restoration was cured once again for 20 seconds and dental isolation was removed to perform occlusal adjustments (Carbon Paper Contacto Film, Angelus, Londrina, PR, Brazil). The polish and finish procedures were performed with finishing diamond burrs (Finishing Kit Fine and Ultrafine Grain, KG Sorensen, Agerskov, Denmark) in low speed rotation, sanding discs (16mm diameter, TDV, Pomerode, SC, Brazil) in decreasing order of abrasiveness, silicon rubber polishing abrasive burs (Mini Resin Polishing Kit, Microdont, Londrina, PR, Brazil) and round felt discs (12mm diameter, TDV, Pomerode, SC, Brazil) with polishing pastes (Diamond AC I e AC II, FGM, Joinville, SC, Brazil) [Picture 14].
Element 46 - For element 46, it was proposed the bulk technique with low viscosity composite Surefil SDR Flow (Dentsply Sirona, York, PA, USA, universal color) plus occlusal coverage in conventional resin composite (Tetric N Ceram, Ivoclar Vivadent, Schaan, Liechtenstein, color A2). After local anesthesia of the inferior alveolar nerve with lidocaine and epinephrine (Alphacaine 2%), the deficient restoration in resin composite was removed with sphere diamond burr nº 1014 (KG Sorensen) under refrigeration in high speed rotation. With the same burr, the cavity’s contour and convenience shapes were defined. During restoration removal, a previous pulp capping was found and removed, showing a darkened and mineralized tertiary dentin. Therefore, after dental isolation, which was extended only up until element 44 due to the presence of orthodontic retainer, the pulp chamber surface was covered with a thin layer of resinous glass ionomer cement (Vitremer, SS White, New Jersey, NY, USA) [Picture 15], which was cured for 20 seconds. After, the cavity depth was measured with a millimeter probe, indicating a 4mm depth (Picture 16). The cavity hybridization was performed with universal self-etching adhesive system (Single Bond Universal), starting with selective conditioning of the enamel restricted to the cavosurface angle with 37% phosphoric acid (Alpha Etch) for 30 seconds (Picture 17). Next, the acid was abundantly rinsed for 30 seconds with air-water jet and the cavity was dried with air jet. Next, a drop of the universal adhesive was actively applied in the whole cavity for 20 seconds (Picture 18), followed by a light air jet for 5 seconds and cured for 10 seconds with LED light photopolymerizer (Bluephase). After curing, the first 2mm of the cavity were filled with Surefil SDR resin with its own disposable applicator tip (Picture 19), leaving 2mm to be restored with conventional resin composite (Picture 20). The Surefil SDR layer was cured for 20 seconds. The occlusal coverage with Tetric N Ceram was built with the traditional buildup layering technique, limiting each increment to each cusp (Picture 21). Each increment was cured for 20 seconds. Additionally, characterization colors (Empress Direct Color) were applied on the depth of the main grooves (color ochre) and on cusps ridges (color white) [Picture 22]. Afterwards, the restoration was cured onceagain for 20 seconds and dental isolation was removed to perform occlusal adjustments (Carbon Paper Contacto Film). The polish and finish procedures were performed with finishing diamond burrs (Finishing Kit Fine and Ultrafine Grain, KG Sorensen) in low speed rotation, sanding discs (16mm diameter, TDV) in decreasing order of abrasiveness, silicon rubber polishing abrasive burs (Mini Resin Polishing Kit, Microdont) and round felt discs (12mm diameter, TDV) with polishing pastes (Diamond AC I e AC II) [Picture 23].
Element 48 - Although element 48 had presented clinical indications of a potential class I restoration, its periapical radiograph didn’t show any carious lesions deep enough to qualify it into the standardized comparison between class I restorations.
Clinical evaluation of marginal adaptation - Immediately after polishing and finishing the restorations, each one of them were evaluated and rated based on the USPHS criteria for direct clinical evaluation modified by Van Dijken e Pallesen (2015), which included the following parameters: anatomical form, marginal adaptation, color match, marginal discoloration, surface roughness and caries (Table 1). The scores for elements 37 and 46’s restorations are listed in tables 2 and 3, respectively. 
Table 1 – USPHS criteria for direct clinical evaluation modified by Van Dijken e Pallesen (2015)
Tabela 1 – Critério USPHS de adaptação marginal modificado por Van Dijken e Pallesen (2015)
	Categoria
	Pontuação
	Critério
	Anatomical
form
	0
	The restoration is contiguous with tooth anatomy
	
	1
	Slightly under- or over-contoured restoration; marginal ridges slightly undercontoured; contact slightly open (may be self-correcting); occlusal height reduced locally
	
	2
	Restoration is undercountored, dentin or base exposed; contact in faulty, not self-correcting; occlusal height reduced; occlusion affected
	
	3
	Restoration is missing partially or totally; fracture of tooth structure; shows traumatic occlusion; restoration causes pain in tooth or adjacent tissue
	Marginal
adaptation
	0
	Restoration is contiguous with existing anatomic form, explorer does not catch
	
	1
	Explorer catches, no crevice is visible into which explorer will penetrate
	
	2
	Crevice at margin, enamel exposed
	
	3
	Obvious crevice at margin, dentin or base exposed
	
	4
	Restoration mobile, fractured or missing
	Color match
	0
	Very good color match
	
	1
	Good color match
	
	2
	Slight mismatch in color, shade or translucency
	
	3
	Obvious mismatch, outside the normal range 
	
	4
	Gross mismatch
	Marginal
descoloration
	0
	No discoloration evident
	
	1
	Slight staining, can be polished away
	
	2
	Obvious staining, cannot be polished away
	
	3
	Gross staining
	Surface
roughness
	0
	Smooth surface
	
	1
	Slightly rough or pitted
	
	2
	Rough, cannot be refinished
	
	3
	Surface deeply pittted, irregular grooves
	Caries
	0
	No evidence of caries contiguous with the margin of the restoration
	
	1
	Caries is evident contiguous with the margin of the restoration
Table 2 – USPHS criteria score of Element 37
	Elemento 37
	Category
	Score
	Anatomical form
	1
	Marginal adaptation
	0
	Color match
	2
	Marginal discoloration
	0
	Surface roughness
	0
	Caries
	0
Table 3 – USPHS criteria score of Element 46
	Elemento 46
	Category
	Score
	Anatomical form
	0
	Marginal adaptation
	0
	Color match
	1
	Marginal discoloration
	0
	Surface roughness
	0
	Caries
	0
DISCUSSION 
The present study aimed to demonstrate, through a clinical case study, the different techniques used to perform posterior restorations with resin composites, comparing the buildup layering technique of conventional resin composites to the bulk technique of bulk fill composites of high and low viscosity. However, while working on element 36, on which the buildup technique would be performed, the risk of pulp exposure was established and an expectant treatment was opted as a way of prevention and stimulation of tertiary dentin formation. Therefore, it was only possible to demonstrate the restorative techniques involving bulk fill composites in both high and low viscosities. 
	Since the appearance of resin composites in Restorative Dentistry as effective restorative materials, manufacturers have been looking for alternatives to improve their physical and mechanical properties (MOORTHY et al., 2012). The decrease of particles size in their composition and the use of the buildup layering technique are examples of strategies used to overcome the limitations and complications of these materials, such as polymerization shrinkage, marginal microleakage and limited depth of cure (VAN DIJKEN and PALLESEN, 2015). In this context, within the range of available manufactured resin composites, the nanoparticuled resins provide greater fracture resistance, better hardness and aesthetics, as well as a more gradual polymerization reaction, decreasing, consequentially, the shrinkage stresses (KOÇVURAL et al., 2017). However, the undesirable features of these composites are still present, and alternative materials that might provide a much simpler clinical protocol without affecting physical-mechanic properties are attractive (VAN ENDE et al., 2016). 
	Considering all the limitations presented by conventional composite resins, the bulk fill composites appear to simplify and speed up clinical protocol of extensive posteriors restorations, introducing the single increment technique up to 4 mm thickness as long as there is a proper curing protocol (ILIE e STARK, 2014). The bulk fill materials might present a true clinical advantage in case they reach greater depths of cure while simultaneously decreasing shrinkage stresses and providing adequate adaptation to dental substrates (AGARWAL et al., 2015). The main differences between bulk fill composites and conventional resin composites lie on their compositions: compared to conventional composites, most bulk fill materials have smaller proportion and larger size of inorganic particles, with the main goal of increasing translucency and, consequently, reaching greater depth of cure (ILIE et al., 2014; VAN DIJKEN and PALLESEN, 2015; RENGO et al., 2015). Besides, modified monomers, modulators and “polymerization boosters” were added to most bulk fill materials’ compositions (FLURY, PEUTZFELDT e LUSSI, 2014; HIRATA et al., 2015). Furthermore, the use of bulk fill composites may be considered promising in Pediatric Dentistry, where patients tend to be uncooperative (ILIE et al., 2014), in restorative procedures of extensive endodontic accesses (ISUFI et al., 2016) and also in repairing of deficient restorations (KOÇ-VURAL et al., 2017). 
	The strategy elected to restore the element 37 was the bulk technique with bulk fill composite of high viscosity (Tetric N Ceram Bulk Fill). This material has on its composition a specific photoinitiator called Ivocerin®, which is described as an initiator system based on germanium compounds, with higher absorption capacity and photopolymerization activity compared to camphorquinone. This photoinitiator has the ability of forming two radicals to initiate polymerization reaction instead of one, like the camphorquinone-amine system (ILIE et al., 2014; KIM et al., 2015). Indeed, in the study conducted by Son et al. (2017), this composite presented a low polymerization shrinkage, which was attributed to its high inorganic particle content. Additionally, in the study conducted by Kim et al. (2015), bulk fill composites, including Tetric N Ceram Bulk Fill, showed minor changes in hardness properties related to increment thickness variation, while conventional resin composites presented a drastic decrease of microhardness for a 4mm thick increment. In contrast, the results of Agarwal et al. (2015)’s research showed inadequate internal adaptation in dentin for restorations made out of Tetric N Ceram Bulk Fill, which might be related to its restricted flowability, inadequate to fill the cavity’s sharp corners and internal angles. However,for enamel substrate, the bulk fill and conventional composites resulted in a similar proportion of crevice absence. 
	The Surefil SDR composite, used as base to restore element 46, has on its composition a polymerization modulator based on uranium in high molecular weight, which is capable of slowing up curing process and reducing polymerization shrinkage without affecting the degree of conversion (ILIE e STARK, 2014; JAGANATH et al., 2017). Furthermore, this composite had its main monomer (Bis-GMA) completely replaced by less viscous dimethacrylates, such as UDMA, TEGDMA and EBPDMA, capable of building more flexible and stable polymer chains and also decreasing polymerization shrinkage. These particularities of its chemical composition have direct effect on the composition’s curing behavior, as well as on its mechanical properties (ILIE and STARK, 2014). It is also assumed that the higher the filler loading in resin composites, the higher their mechanical properties, and Surefil SDR presents a filler loading corresponding to approximately 50% of its composition, a relatively high proportion within the range of flow composites (DIDEM, GOZDE and NURHAN, 2014). In this context, in previous studies, this composite showed significant lower values of polymerization shrinkage compared to nanohybrid resin composites and even to silorane based composites (FRONZA et al., 2018; MEEREIS et al., 2018). Besides its lower polymerization shrinkage, Surefil SDR composite showed significant advantages in regarding internal adaptation, consolidating its indication for restoring deep and narrow cavities (ILIE et al., 2014). In a study conducted by Orlowski, Tarczydlo and Chalas (2014), 93,33% of restorations made out of SDR composite didn’t show any marginal microleakage, which might be directly related to its low shrinkage stress and low viscosity. Furthermore, when used in an single layer of 4mm thickness, this composite didn’t show any significant differences regards marginal integrity in enamel, middle dentin or pulp margin (ROGGENDORF et al., 2011; FURNESS et al., 2014). Surefil SDR composite’s low viscosity is obtained without decreasing the quantity of its filler load, which is propitious for achieving adequate internal adaptation without reducing microhardness properties (KIM et al., 2015). 
	Bulk fill composites with low viscosity are often used as base for extensive restorations and tend to present lower percentage of filler loading compared to high viscosity composites (FLURY, PEUTZFELDT e LUSSI, 2014; JUNG e PARK, 2017; MEEREIS et al., 2018). This feature may cause a decrease of microhardness properties, requiring a occlusal coverage made out of conventional resin composite (KIM et al., 2015; TEKIN et al., 2017) to achieve adequate anatomic, functional and aesthetic features for the restoration (MOORTHY et al., 2012). This situation can be observed after applying the modified USPHS criteria, which showed more satisfactory scores for anatomic form category (Tables 2 and 3). Bulk fill flow composites, when used as base for restorations, act like stress absorbing layers between the restoration and dental structure due to its low modulus of elasticity, and its consistency allows a better adaptability to the cavity walls (JAGANATH et al., 2017). Moreover, another benefit offered by this technique is the reduced operation time, as well as the fewer increments needed to be inserted and cured during the occlusal coverage’s buildup technique (MOORTHY et al., 2012). In this context, the occlusal coverage of element 46 was made out of Tetric N Ceram composite, allowing a reliable marginal adaptation comparison between elements 37 and 46 since this composite is the precursor of Tetric N Ceram Bulk Fill. The comparison of materials marketed by different manufacturers is difficult, considering that parameters such as particle size, morphologies, monomer types and photoinitiation chemistry vary greatly among the product range (LEPRINCE et al., 2014).
	The universal adhesive system with selective enamel conditioning was elected for the present study. The etching with 37% phosphoric acid in enamel’s cavosurface angle is still the most reliable way to achieve resistant enamel bonds due to a micromechanical retention mechanism between hydroxyapatite crystals (ROGGENDORF et al., 2011; AGARWAL et al., 2015). It is also important to consider that in deeper preparations dentin substrate presents less intertubular area and higher moisture, therefore only a small solid dentin area is available for hybridization, consequently producing weaker bond strengths (FRONZA et al., 2018). 
	Immediately after finishing the restorations, the marginal adaptation was evaluated according to the USPHS criteria modified by Van Dijken and Pallesen (2015). In agreement with Hirata et al. (2015) and according to USPHS criteria, all techniques demonstrated in the present study showed satisfactory aesthetic and functional features. However, one of the main contrasts between the two techniques was the color match category, on which element 37 scored “2” (Slight mismatch in color, shade or translucency) and and element 46 scored “1” (Good color match). These findings are in accordance with the reviewed literature, which states that bulk fill composites are more translucent compared to conventional resin composites. With greater translucency, the bulk fill resin composites allow more light to penetrate deep inside the restoration, resulting in more polymerized monomers at the bottom surface (KIM et al., 2015). Light transmittance to the depth of the bulk fill restoration is critical to achieve adequate depth of cure, thus, translucency has been indicated as a relevant property for bulk fill composites (RENGO et al., 2015). In this context, compositions are modified in order to slow up polymerization reaction and, consequentially, decrease polymerization shrinkage stresses (PAR et al., 2014; GONÇALVES et al., 2018). In conventional resin composites, the presence of pigments in their formulations limits light penetration and reduces polymerization at depth due to their opacity (RENGO et al., 2015). However, these pigments can result in a more satisfactory aesthetic, since they favor the reproduction of the aspects of a natural tooth, such as its different opacities, shades and translucencies (HIRATA et al., 2015). Furthermore, in the study conducted by Shamszadeh et al. (2016), the differences in bulk fill composites’ compositions can negatively influence on staining susceptibility and discoloration caused by layer thickness increase. 
	It is important to consider that, in the present clinical case study, the USPHS criteria were applied immediately after the initial polishing and finishing of restorations, and some inherent material properties might only be observed after periodic evaluations. Physiological and mechanical degradation caused by oral fluids and chewing effects are pointed as intensifying factors of the process of marginal microleakage formation (SCOTI et al., 2014). Still, according to the reviewed literature, bulk fill composites in both viscosities can be considered valid alternatives for building posterior class I restorations. According to the systematic review conducted by Reis et al. (2017), the evaluated bulk fill composites were considered partially capable of meeting the important requirement of adequate curing in 4 mm deep cavities. In 60% of the studies this statement was partially accepted and, in 40%, accepted completely. The results shown in this systematic review were exclusively based on in vitro studies and, still, in recent clinical rehearsals the bulk technique showed high clinical efficiency. This statement is in accordance to Furness et al. (2014), that showed that restorations made out of bulk fill composites and conventional resin composites result in a similar marginal adaptation proportion on both middle dentin and enamel interfaces. 
	The filling of cavities in thicknesses greater than 4 mm can be convenient andtime saving. Moreover, the bulk techniques are considered alternatives to the potential complications of the traditional buildup layering technique, such as restored teeth deformity, stress formation in the tooth-restoration interface and gaps between increments (CAMPOS et al., 2014). However, due to inconsistent and contradictory results on light transmission in bulk fill composites, a careful selection of these materials should be carried out to ensure quality and durability of restorations (VAND ENDE et al., 2016; SON et al., 2017), considering the dental tissue to be restored and aiming to obtain an adequate marginal seal (SCOTTI et al., 2014). 
	In this context, to obtain success in restorations made out of bulk fill composites, it is essential that the clinical protocols advised by the manufacturers are respected, as well as the materials’ indications and correct use of the proposed techniques (ORLOWSKI, TARCZYDLO e CHALAS, 2014; SON et al., 2017; GONÇALVES et al., 2018; MEEREIS et al., 2018). Still, more clinical evaluations of these techniques and composites are necessary, specially to establish long-term anatomical forms and marginal adaptation stability compared to the traditional resin composites.
CONCLUSION
	Based on the present clinical case study and reviewed literature, it can be established that the bulk fill technique is able to replace the buildup layering technique in posterior restorations, as long as there is a careful selection of materials and the correct clinical indications and protocols are respected. Bulk fill techniques with high and low viscosity composites present a clear advantage in regarding simplification of clinical protocol, and should be considered specially for performing extensive restorations in uncooperative patients. To achieve a proper internal adaptation in the use of these composites, the clinical operator has to present knowledge and skills in regarding insertion, adaptation and anatomization of the material in the cavity. In addition, it was observed that aesthetic disadvantages caused by high translucency of high viscosity bulk fill composites can be improved by using color characterization materials on fissures and cusps. Finally, it is important to establish that the dentist surgeon must be the one to judge and select the most appropriate composites and techniques for the resolution of each particular case. 
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JUNG, J. H.; Park, S. H. Comparison of Polymerization Shrinkage, Physical Properties, and Marginal Adaptation of Flowable and Restorative Bulk Fill Resin-Based Composites. Oper Dent. v. 42, n. 4, p. 375-386. Julho 2017. 
KIM, E. et al. Effect of resin thickness on the microhardness and optical properties of bulk-fill resin composites. Restor Dent Endod. v. 40, n. 2, p. 128-135. Maio 2015. 
KOÇ-VURAL, U. et al. Bond strength of dental nanocomposites repaired with a bulkfill composite. J Clin Exp Dent. v. 9, n. 3, p. 437-442. Março 2017. 
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	Picture 1
	Initial photographic image of the mandibular arch. Elements 36, 37 and 46 with deficient class I restorations and element 47 with fissure pigmentation.
	Picture 2
	Periapical radiograph image of elements 36, 37 and 38.
	Picture 3
	Periapical radiograph image of elements 46, 47 and 48.
	Picture 4
	Initial photographic image of elements 36 and 37. On 36, the amalgam surface shows staining and marginal maladjustment (). On 37, there are oxidation areas and marginal degradation (*) throughout the entire resin composite restoration.
	Picture 5
	Initial photographic image of elements 46 and 47. On47, there are oxidation areas (*) and fracture () throughout the margins of the resin composite restoration. On 46, there is caries lesion throughout the tooth’s grooves and fissures. 
	Picture 6
	Photographic image of element 37’s cavity preparation.
	Picture 7
	Photographic image of dental isolation of elements 34, 35, 36 and 37.
	Picture 8
	Photographic image of millimeter probe positioning to measure the cavity depth (4 mm). 
	Picture 9
	Photographic image of the enamel’s selective conditioning with 37% phosphoric acid for 30 seconds. 
	Picture 10
	Photographic image of the active application of self-etching universal adhesive for 20 seconds. 
	Picture 11
	Photographic image of the insertion of resin composite with brunisher nº 33. 
	Picture 12
	Photographic image of groove anatomization with explorer tool nº 5. 
	Picture 13
	Photographic image of the final restoration after application of the characterization colors and before initial polishing and finishing.
	Picture 14
	Photographic image of the final restoration after initial polishing and finishing. 
	Picture 15
	Photographic image of dental isolation of elements 45, 46 and 47 and 46’s cavity preparation with resin modified glass ionomer cement as a thin liner on the pulp surface. 
	Picture 16
	Photographic image of millimeter probe positioning to measure the cavity depth (4 mm). 
	Picture 17
	Photographic image of the enamel’s selective conditioning with 37% phosphoric acid for 30 seconds.
	Picture 18
	Photographic image of the active application of self-etching universal adhesive for 20 seconds. 
	Picture 19
	Photographic image of the application of Surefil SDR composite resin with its own disposable applicator tip.
	Picture 20
	Photographic image indicating the remaining depth of the cavity after the insertion of the Surefil SDR composite (2 mm). 
	Picture 21
	Photographic image of the insertion of Tetric N Ceram composite increments. Each cusp received an increment, which were cured for 20 seconds each. 
	Picture 22
	Photographic image of the final restoration after application of the characterization colors and before initial polishing and finishing. 
	Picture 23
	Photographic image of the final restoration after initial polishing and finishing.
Figure 1 – Initial photographic image of the mandibular arch. Elements 36, 37 and 46 with deficient class I restorations and element 47 with fissure pigmentation.
Figure 3 – Periapical radiograph image of elements 46, 47 and 48
Figure 2 – Periapical radiograph image of elements 36, 37 and 38.
Figure 4 – Initial photographic image of elements 36 and 37. On 36, the amalgam surface shows staining and marginal maladjustment (). On 37, there are oxidation areas and marginal degradation (*) throughout the entire resin composite restoration.
*
*
*
*
*
Figure 5 – Initial photographic image of elements 46 and 47. On 47, there are oxidation areas (*) and fracture () throughout the margins of the resin composite restoration. On 46, there is caries lesion throughout the tooth’s grooves and fissures.
Figure 6 – Photographic image of element 37’s cavity preparation
Figure 7 – Photographic image of dental isolation of elements 34, 35, 36 and 37.
Figure 8 – Photographic image of millimeter probe positioning to measure the cavity depth (4mm). 
Figure 10 – Photographic image of the active application of self-etching universal adhesive for 20 seconds.
Figure 9 - Photographic image of the enamel’s selective conditioning with 37% phosphoric acid for 30 seconds. 
 .
Figure 13 – Photographic image of the final restoration after application of the characterization colors and before initial polishing and finishing.
 
Figure 14 – Photographic image of the final restoration after initial polishing and finishing
Figure 11 – Photographic image of the insertion of resin composite with brunisher nº 33..
Figure 12 – Photographic image of groove anatomization with explorer tool nº 5.
Figure 16 – Photographic image of millimeter probe positioning to measure the cavity depth (4 mm). 
Figure 15 – Photographic image of dental isolation of elements 45, 46 and 47 and 46’s cavity preparation with resin modified glass ionomer cement as a thin liner on the pulp surface.
Figure 17 – Photographic image of the enamel’s selective conditioning with 37% phosphoric acid for 30 seconds. 
Figure 18 – Photographic image of the active application of self-etching universal adhesive for 20 seconds.
Figure 20 – Photographic image indicating the remaining depth of the cavity after the insertion of the Surefil SDR composite (2mm).
2 mm
Figure 19 – Photographic image of the application of Surefil SDR composite resin with its own disposable applicator tip
Figure 21 – Photographic image of the insertion of Tetric N Ceram composite increments. Each cusp received an increment, which were cured for 20 seconds each.
Figure 22 – Photographic image of the final restoration after application of the characterization colors and before initial polishing and finishing
Figure 23 – Photographic image of the final restoration after initial polishing and finishing.