Paulo Santos-Filho - Academia.edu (original) (raw)

Papers by Paulo Santos-Filho

General dentistry

With the advent of new adhesive technologies, fiber-reinforced composite fixed partial dentures (... more With the advent of new adhesive technologies, fiber-reinforced composite fixed partial dentures (FRC-FPDs) have become an inexpensive, esthetic and useful restorative option for patients missing a single tooth. This article describes a case involving an inlay-retained FRC-FPD with a prefabricated fiber-reinforced pontic substructure. In addition, a 6-year follow-up is presented. The FRC-FPD fully restored the single missing molar with simple and conservative intracoronal preparations in the proximal teeth and was deemed clinically acceptable after the evaluation period. The clinical procedures to build a FRC-FPD with a prefabricated fiber-reinforced pontic substructure typically are finished by the clinician in 1 or 2 visits without laboratory assistance, making it a viable alternative for patients who cannot afford implant-based treatment or a conventional metal-ceramic FPD.

... The dentin surface was scanned after enamel was removed by HCl-2% acid solution. The scanned ... more ... The dentin surface was scanned after enamel was removed by HCl-2% acid solution. The scanned surfaces were exported to Bio-CAD software where the pulp, PDL and a polymer-cylinder were created to simulate the experimental conditions. ...

Dental Traumatology, 2015

Background/Aim: The aim of this study was to evaluate the tooth stresses and strains, shock absor... more Background/Aim: The aim of this study was to evaluate the tooth stresses and strains, shock absorption, and displacement during impact of custom-fitted mouthguards with different thicknesses. Methods: Six bar-shaped specimens of the EVA were made and subjected to tensile test for elastic modulus assessment. Two-dimensional plane-strain models of a human maxillary central incisor, periodontal ligament, bone support, soft tissue, and mouthguard (MTG) were created. The mouthguards were modeled in five different thicknesses (2, 3, 4, 5, and 6 mm). One model was created without mouthguard. A nonlinear dynamic impact analysis was performed in which a rigid object hit the model at 1 m s À1 . Strain and stress (von Mises and Critical modified von Mises) distributions were evaluated, and the displacement of the mouthguard with respect to the tooth was calculated. Results: The mean [SD] for the EVA elastic modulus was 18.075 [0.457] MPa. The model without mouthguard showed the highest stress values at the enamel and dentin structures in the tooth crown during the impact. For the MTG models, the location of the stress concentrations changed to the root, regardless of the MTG thickness, but maximum stresses in the enamel and dentin were lower compared with the model without MTG. Increasing the mouthguard thickness did not notably decrease the stress-strain values. Conclusion: It was concluded that the use of a mouthguard promoted lower stresses and strains in teeth during an impact with a rigid object. There was no substantial difference in peak stresses and strains and in shock absorption among the different mouthguard thicknesses.

Objective: The purpose of this study was to investigate the influence of post and crown type and ... more Objective: The purpose of this study was to investigate the influence of post and crown type and ferrule presence on stress distribution, strain, fracture resistance and mode of failure of root filled teeth. Method: The investigation was conducted by using 3D finite element analysis (FEA) and in-vitro tests. 3D models of a maxillary central incisor were generated: WFe, without ferrule; Fe1, 1.0 mm of ferrule; and Fe2, 2.0 mm of ferrule; restored with glass fiber post (Gfp) or cast post-and-core (Cpc); and metal crowns (Mc) or alumina-reinforced ceramic crowns (Cc). Each FE model was subjected to 100 N oblique loads. The results were evaluated by von Mises criterion and Principal maximum stress. One hundred and twenty bovine incisors were selected and divided into 12 treatment groups (n=10). Treatment variations were the same as used in finite element analysis. The teeth were loaded at a 135-degree angle, and the root strain was measured. Specimens were subsequently loaded until frac...

Objective: To evaluate the micropush-out bond strength influence of self-cured and dual-cured lut... more Objective: To evaluate the micropush-out bond strength influence of self-cured and dual-cured luting systems and degree of conversion these systems. Method: Forty single-rooted bovine teeth were root filled and prepared to receive fiberglass post Exacto nº 3 [Angelus]. The luting systems (LS) tested were (n=10): All Bond 2 (AB)/C&B (CB) [Bisco], Fusion Duralink (FD)/Cement-Post (CP) [Angelus], SingleBond 2 (SB)/Rely X ARC (ARC) [3M Espe] and Rely X U100 (U100) [3M Espe]. Two slices for cervical, middle and apical third of root were obtained. The slices were tested with micropush-out test (MBS) at a speed of 0.5 mm min¯¹. Degree of conversion (DC) was determined by Fourier transform infrared spectroscopy (FT-IR) (n=3). The MBS and DC values were analyzed using ANOVA and Tukey’s test (p < 0.05). Result: The table shows MBS (MPa) and DC mean (%) and standard deviations for experimental groups. Luting System Third - MBS (MPa) DC (%) Cervical Middle Apical AB/CB 12.0±7.1Aab 5.6±2.9Ba ...

Brazilian Dental Journal, 2015

Failures may occur in the connections of dental implants, especially in external hexagon (EH). Du... more Failures may occur in the connections of dental implants, especially in external hexagon (EH). Due to the deformations in this portion of implants, this study aimed to evaluate the levels of deformation of EH connections subjected to internal toque. Two types of implants were used: N group and S group. Torques of 0, 32, 45, 60 and 80 Ncm were applied to the N group, and torques of 0, 30, 40, 60 and infinite Ncm were applied to the S group implants. The internal distance (ID), internal area (IA) and external area (EA) of the EH were obtained from digital pictures, which were analyzed by a specific software. Statistical analysis was performed by the Scott-Knott test. The results showed that the higher the torque applied, the greater were the changes in the evaluated dimensions in both groups. In the S group, torque levels equal or greater than 40 Ncm and 30 Ncm caused greater deformation of EA and IA respectively, while in the N group, torque levels equal or greater than 60 Ncm and 32 Ncm caused greater deformation of EA and IA respectively. Levels of deformation were greater in the S group as compared with the N group. These findings suggest that the IA, EA and ID of the EH may be affected by different internal torque levels.

American journal of dentistry, 2015

To investigate the influence of a high elastic modulus material insert on the stress, shock absor... more To investigate the influence of a high elastic modulus material insert on the stress, shock absorption and displacement of mouthguards. Finite element models of a human maxillary central incisor with and without mouthguard were created based on cross-sectional CT-tomography. The mouthguard models had four designs: without insert, and middle, external, or palatal hard insert. The hard inserts had a relatively high elastic modulus when compared to the elastic modulus of ethylene vinyl acetate (EVA): 15 GPa versus 18 MPa. A non-linear dynamic impact analysis was performed in which a heavy rigid object hit the model at 1 m/s. Strain and stress (von Mises and critical modified von Mises) distributions and shock absorption during impact were calculated as well as the mouthguard displacement. The model without mouthguard had the highest stress values at the enamel and dentin structures in the tooth crown during the impact. It was concluded that the use of a mouthguard promoted lower stress...

Dental traumatology : official publication of International Association for Dental Traumatology, Jan 3, 2015

Custom-fitted mouthguards are devices used to decrease the likelihood of dental trauma. The aim o... more Custom-fitted mouthguards are devices used to decrease the likelihood of dental trauma. The aim of this study was to develop an experimental bovine dentoalveolar model with periodontal ligament to evaluate mouthguard shock absorption, and impact strain and stress behavior. A pendulum impact device was developed to perform the impact tests with two different impact materials (steel ball and baseball). Five bovine jaws were selected with standard age and dimensions. Six-mm mouthguards were made for the impact tests. The jaws were fixed in a pendulum device and impacts were performed from 90, 60, and 45° angles, with and without mouthguard. Strain gauges were attached at the palatal surface of the impacted tooth. The strain and shock absorption of the mouthguards was calculated and data were analyzed with 3-way anova and Tukey's test (α = 0.05). Two-dimensional finite element models were created based on the cross-section of the bovine dentoalveolar model used in the experiment. A ...

Brazilian Dental Journal, 2015

Despite several advantages associated with pre-fabricated glass-fiber posts, the coronal portion ... more Despite several advantages associated with pre-fabricated glass-fiber posts, the coronal portion of these posts must be cut to allow their use in various clinical situations. However, cutting the cemented post can generate stress on the bonding interface and affect the bond strength. The aim of this study was to investigate the effect the of fiber post cutting on the bond strength of root canals. Sixty bovine incisor roots were included in resin cylinders with simulated periodontal ligaments. Glass-fiber posts were luted using regular resin cement RelyX ARC (3M ESPE) or self-adhesive cement RelyX Unicem (3M ESPE). The posts were cut prior to cementation, immediately after luting or after building up the core (n=10). After storage for 24 h, the samples were cut and subject to push-out testing using a mechanical testing machine (EMIC DL 2000). Data were analyzed using two-way ANOVA (resin cement x moment of post cutting) and Tukey's post hoc test (α=0.05). The moment of fiber post cutting did not affect the bond strength when Unicem was used. However, the bond strength was reduced when ARC was used and when the post was cut immediately. In conclusion, the moment of fiber post cutting may affect the retention of root canal posts when a regular resin cement is used.

Objective: To evaluate the biomechanical behavior of endodontically treated anterior teeth by str... more Objective: To evaluate the biomechanical behavior of endodontically treated anterior teeth by strain measurement, finite element analysis (FEA), and fracture resistance by varying the presence of ferrule and length of different endodontic posts. Methods: Eighty bovine incisor roots were selected and divided into 2 groups (n = 40): with ferrule of 2.0 mm, with no ferrule. These groups were divided into 4 subgroups (n = 10) varying the endodontic posts: fiberglass posts and cast post-and-cores, in lengths of 12 and 7 mm. All roots were restored with metal crowns. Five specimens from each group were subjected to strain-gage measurement. The fracture resistance was measured in mechanical testing machine with application of tangential load at an angle of 135 ° with the long axis of the tooth. Data were submitted to factorial analysis of variance. The failure pattern was analyzed in accordance with the degree of damage to the tooth structure.Tridimensional models of each experimental grou...

Objective: The aim of this study was to quantify the influence of direct and indirect restorative... more Objective: The aim of this study was to quantify the influence of direct and indirect restorative techniques on stress distribution pattern of maxillary premolar by 3D finite element method. Method: One intact maxillary premolar was selected and the enamel/root boundaries were scanned using a contact-scanner (LPX-400, Roland, USA) in which 3D-stereolithography files were obtained. On the next step, the enamel and dentin were sequentially degraded with HCl-2% acid solution. The dentin/pulp boundaries were scanned. These files were exported to Bio-CAD software (Rhino3D). The volumes of each structure were obtained by NURBS surfaces association. In this software, the periodontal-ligament simulation was made. All volumes were exported to Finite Element software packages (NeiNastran and FEMAP). The meshes of each structure were created with tetrahedral nodes, according to mechanical properties obtained by literature review. A linear-static-isotropic model and boundary conditions were cre...

The journal of contemporary dental practice, 2007

The aim of this article is to describe a step-by-step protocol for emergency care of a patient wi... more The aim of this article is to describe a step-by-step protocol for emergency care of a patient with a dentoalveolar injury in the anterior region of the mouth as well as the fabrication of a mouthguard to prevent future trauma. Dental trauma is one of the most serious oral health problems in active children and adolescents. Care of traumatized patients requires immediate initial emergency treatment followed by integrated procedures to restore damaged oral structures along with a subsequent trauma prevention strategy. Dentoalveolar injuries in the anterior region of the mouth are often characterized by tooth avulsion and coronal fracture. They are managed using procedures such as dental splinting, endodontic therapy with its unique characteristics, and restorative techniques to re-establish function and esthetics as well as protective mouthguards. A 16-year-old male presented with avulsion of his maxillary central incisors as a result of a direct, unintentional impact with an opponen...

Acta odontológica latinoamericana : AOL, 2012

This study evaluated the effect of adhesive application only to enamel on the marginal microleaka... more This study evaluated the effect of adhesive application only to enamel on the marginal microleakage of composite resin restorations performed with different adhesive systems. Standardized cylinder-shaped cavities were prepared on the buccal surface of eighty bovine incisors. Two etch-and-rinse (Adper Scotchbond Multi-purpose [3M ESPE, St. Paul, MN USA] and Adper Single Bond 2 [3M ESPE]) and two self-etching (Clearfil SE Bond [Kuraray, Osaka, Japan] and Adper Prompt [3M ESPE]) adhesive systems were evaluated. The adhesives were applied only to enamel or to both dentin and enamel. After adhesive light-activation, the cavities were restored with composite resin. The samples were coated with two layers of nail polish, except an area of 1-mm wide around of the restoration, and immersed in a methylene blue solution. Afterwards, the specimens were ground in order to obtain powder which was immersed in absolute alcohol. The solutions were centrifuged and the supernatant was analyzed using a...

Brazilian oral research

The aim of this study was to evaluate the effect of parallel and tapered threaded post placement ... more The aim of this study was to evaluate the effect of parallel and tapered threaded post placement on the strain and stress distribution of endodontically treated teeth. Fifteen bovine incisors were sectioned 15 mm from their apices, endodontically treated, and divided into three groups (n=5) according to three different threaded posts: parallel threaded post (Radix-Anker, RA); tapered threaded post (Euro-Post, EP) and tapered threaded post (Reforpost II, RII). A strain-gauge was fixed on the proximal surface perpendicular to the long root axis, 2 mm from the cervical limit. Strain generated during post placement was recorded and compared using one-way ANOVA and Tukey's test (α=.05). A scanning electron microscope was used to examine the longitudinal root sections. Stress was evaluated for each group in a two-dimensional finite element analysis. The models were meshed with tetrahedron elements and loaded with 2 N at an angle of 135° to the lingual face. The equivalent Von Mises st...

Journal of Endodontics, 2014

Introduction: The aim of this study was to evaluate the influence of a ferrule, post system, and ... more Introduction: The aim of this study was to evaluate the influence of a ferrule, post system, and length on the stress distribution of weakened root-filled teeth. Methods: The investigation was conducted by using 3-dimensional (3D) finite element analysis. A sound tooth and 8 3D models of a weakened root-filled central incisor were generated using computer-aided design/ computer-aided manufacturing software. The models were created without a ferrule and with a 2.0-mm ferrule, restored with a relined glass fiber post or a cast post and core (Cpc), and 12.0-and 7.0-mm post lengths. Each 3D model was imported using *.STEP files to the finite element software for mesh generation. The models were subjected to 100-N oblique loading at the palatal surface, and the results were evaluated by von Mises criterion and maximum principal stress distribution. Results: Finite element analysis showed that the Cpc models showed elevated stress levels in the root canal regardless of the presence of a ferrule. Relined glass fiber post models showed homogeneous stress distribution to the dentin external surface similar to the sound tooth model. Without a ferrule, Cpc with a 7-or 12mm length promoted high levels of tensile stress inside the root canal. Conclusions: Ferrule presence promoted more satisfactory stress distribution to the roots. Post length influenced the stress distribution only for the models restored with a cast post and core. High levels of tensile stress inside the root canals were verified with a cast post and core, which should be avoided to rehabilitate weakened roots, mainly in the absence of a ferrule. (J Endod 2014;-:1-5)

International Journal of Experimental Dental Science, 2012

This study evaluated the effect of adhesive application only to enamel on the gap formation of co... more This study evaluated the effect of adhesive application only to enamel on the gap formation of composite resin restorations performed with different adhesive systems and submitted to mechanical cycling. Standardized cylinder-shaped cavities were prepared on the buccal surface of 60 bovine incisors. Two etchand-rinse [Adper Scotchbond Multi-purpose (3M ESPE, St. Paul, MN, USA) and Adper Single Bond 2 (3M ESPE)] and one selfetching [Clearfil SE Bond (Kuraray, Osaka, Japan)] adhesive systems were evaluated. The adhesives were applied only to enamel or to both dentin and enamel. After adhesive light activation, the cavities were restored with composite resin. The restorations were finished and polished; the marginal adaptation was analyzed using scanning electronic microscopy (SEM, 500× magnification) in low-vacuum mode. After the first evaluation, the samples were submitted to mechanical cycling (300,000 cycles of 80 kN and 1.5 Hz) and a new evaluation was performed. There was observed any gap for all experimental conditions before and after mechanical cycling. Bonding to dentin does not alter the marginal adaptation of composite restorations.

Journal of Prosthodontics, 2011

Purpose: This in vitro study investigated the null hypothesis that metal-free crowns induce fract... more Purpose: This in vitro study investigated the null hypothesis that metal-free crowns induce fracture loads and mechanical behavior similar to metal ceramic systems and to study the fracture pattern of ceramic crowns under compressive loads using finite element and fractography analyses. Materials and Methods: Six groups (n = 8) with crowns from different systems were compared: conventional metal ceramic (Noritake) (CMC); modified metal ceramic (Noritake) (MMC); lithium disilicate-reinforced ceramic (IPS Empress II) (EMP); leucite-reinforced ceramic (Cergogold) (CERG); leucite fluoride-apatite reinforced ceramic (IPS d.Sign) (SIGN); and polymer crowns (Targis) (TARG). Standardized crown preparations were performed on bovine roots containing NiCr metal dowels and resin cores. Crowns were fabricated using the ceramics listed, cemented with dual-cure resin cement, and submitted to compressive loads in a mechanical testing machine at a 0.5-mm/min crosshead speed. Data were submitted to one-way ANOVA and Tukey tests, and fractured specimens were visually inspected under a stereomicroscope (20×) to determine the type of fracture. Maximum principal stress (MPS) distributions were calculated using finite element analysis, and fracture origin and the correlation with the fracture type were determined using fractography. Results: Mean values of fracture resistance (N) for all groups were: CMC: 1383 ± 298 (a); MMC: 1691 ± 236 (a); EMP: 657 ± 153 (b); CERG: 546 ± 149 (bc); SIGN: 443 ± 126 (c); TARG: 749 ± 113 (b). Statistical results showed significant differences among groups (p < 0.05) represented by different lowercase letters. Metal ceramic crowns presented fracture loads significantly higher than the others. Ceramic specimens presented high incidence of fractures involving either the core or the tooth, and all fractures of polymer crown specimens involved the tooth in a catastrophic way. Based on stress and fractographic analyses it was determined that fracture occurred from the occlusal to the cervical direction. Conclusions: Within the limitations of this study, the results indicated that the use of ceramic and polymer crowns without a core reinforcement should be carefully evaluated before clinical use due to the high incidence of failure with tooth involvement. This mainly occurred for the polymer crown group, although the fracture load was higher than normal occlusal forces. High tensile stress concentrations were found around and between the occlusal loading points. Fractographic analysis indicated fracture originating from the load point and propagating from the occlusal surface toward the cervical area, which is the opposite direction of that observed in clinical situations.

Journal of Prosthodontics, 2010

To test the hypothesis that the type of cement used for fixation of cast doweland-cores might inf... more To test the hypothesis that the type of cement used for fixation of cast doweland-cores might influence fracture resistance, fracture mode, and stress distribution of single-rooted teeth restored with this class of metallic dowels. Materials and Methods: The coronal portion was removed from 40 bovine incisors, leaving a 15 mm root. After endodontic treatment and standardized root canal relief at 10 mm, specimens were embedded in polystyrene resin, and the periodontal ligament was simulated with polyether impression material. The specimens were randomly divided into four groups (n = 10), and restored with Cu-Al cast dowel-and-cores cemented with one of four options: conventional glass ionomer cement (GI); resinmodified glass ionomer cement (GR); dual-cure resin cement (RC); or zinc-phosphate cement (ZP). Sequentially, fracture resistance of the specimens was tested with a tangential load at a 135 • angle with a 0.5 mm/min crosshead speed. Data were analyzed using one-way analysis of variance (ANOVA) and the Fisher test. Two-dimensional finite element analysis (2D-FEA) was then performed with representative models of each group simulating a 100 μm cement layer. Results were analyzed based on von Mises stress distribution criteria. Results: The mean fracture resistance values were (in N): RC, 838.2 ± 135.9; GI, 772.4 ± 169.8; GR, 613.4 ± 157.5; ZP, 643.6 ± 106.7. FEA revealed that RC and GR presented lower stress values than ZP and GI. The higher stress concentration was coincident with more catastrophic failures, and consequently, with lower fracture resistance values. Conclusions: The type of cement influenced fracture resistance, failure mode, and stress distribution on teeth restored with cast dowel-and-cores.

Journal of Prosthodontics, 2008

The aim of this study was to evaluate the effect of endodontic and restorative treatment on the f... more The aim of this study was to evaluate the effect of endodontic and restorative treatment on the fracture resistance of posterior teeth. Materials and Methods: Fifty intact premolars were selected and randomly placed into five groups (n = 10): G1, intact teeth (control); G2, mesial-occlusal-distal (MOD) preparation; G3, MOD preparation restored with composite resin (Z-250, 3M ESPE); G4, MOD preparation and endodontic treatment; and G5, MOD preparation, endodontic treatment, and composite resin restoration. The specimens were submitted to an axial compression load in a mechanical test machine (EMIC), at a speed of 0.5 mm/min. Fracture patterns were analyzed at four levels. Five 2D numerical models were created by Ansys 10.0 for finite element analysis (FEA). Results: Mean values of compressive strength for all groups were (Kgf): G1 (83.6 ± 25.4); G2 (52.7 ± 20.2); G3 (82.1 ± 24.9); G4 (40.2 ± 14.2); G5 (64.5 ± 18.1). Statistical analysis (ANOVA and Tukey's test) showed that fracture resistance of G1 was significantly higher than that of G5, G2, and G4. Resistance of G3 was also higher than that of G2 and G4. Results showed that the tooth resistance is completely maintained when MOD preparation is restored with composite resin and partially recovered when MOD preparation associated with an endodontic access is restored in the same way. The endodontic treatment and composite resin restoration influenced stress distribution in the dental structure. Conclusions: Composite resin restoration plays an important role in recovering tooth strength. With regard to fracture mode, restoration and endodontic treatment increased the incidence of periodontal involvement, which was demonstrated by association with the finite element mechanical test method.

The Journal of Prosthetic Dentistry, 2008

General dentistry

With the advent of new adhesive technologies, fiber-reinforced composite fixed partial dentures (... more With the advent of new adhesive technologies, fiber-reinforced composite fixed partial dentures (FRC-FPDs) have become an inexpensive, esthetic and useful restorative option for patients missing a single tooth. This article describes a case involving an inlay-retained FRC-FPD with a prefabricated fiber-reinforced pontic substructure. In addition, a 6-year follow-up is presented. The FRC-FPD fully restored the single missing molar with simple and conservative intracoronal preparations in the proximal teeth and was deemed clinically acceptable after the evaluation period. The clinical procedures to build a FRC-FPD with a prefabricated fiber-reinforced pontic substructure typically are finished by the clinician in 1 or 2 visits without laboratory assistance, making it a viable alternative for patients who cannot afford implant-based treatment or a conventional metal-ceramic FPD.

... The dentin surface was scanned after enamel was removed by HCl-2% acid solution. The scanned ... more ... The dentin surface was scanned after enamel was removed by HCl-2% acid solution. The scanned surfaces were exported to Bio-CAD software where the pulp, PDL and a polymer-cylinder were created to simulate the experimental conditions. ...

Dental Traumatology, 2015

Background/Aim: The aim of this study was to evaluate the tooth stresses and strains, shock absor... more Background/Aim: The aim of this study was to evaluate the tooth stresses and strains, shock absorption, and displacement during impact of custom-fitted mouthguards with different thicknesses. Methods: Six bar-shaped specimens of the EVA were made and subjected to tensile test for elastic modulus assessment. Two-dimensional plane-strain models of a human maxillary central incisor, periodontal ligament, bone support, soft tissue, and mouthguard (MTG) were created. The mouthguards were modeled in five different thicknesses (2, 3, 4, 5, and 6 mm). One model was created without mouthguard. A nonlinear dynamic impact analysis was performed in which a rigid object hit the model at 1 m s À1 . Strain and stress (von Mises and Critical modified von Mises) distributions were evaluated, and the displacement of the mouthguard with respect to the tooth was calculated. Results: The mean [SD] for the EVA elastic modulus was 18.075 [0.457] MPa. The model without mouthguard showed the highest stress values at the enamel and dentin structures in the tooth crown during the impact. For the MTG models, the location of the stress concentrations changed to the root, regardless of the MTG thickness, but maximum stresses in the enamel and dentin were lower compared with the model without MTG. Increasing the mouthguard thickness did not notably decrease the stress-strain values. Conclusion: It was concluded that the use of a mouthguard promoted lower stresses and strains in teeth during an impact with a rigid object. There was no substantial difference in peak stresses and strains and in shock absorption among the different mouthguard thicknesses.

Objective: The purpose of this study was to investigate the influence of post and crown type and ... more Objective: The purpose of this study was to investigate the influence of post and crown type and ferrule presence on stress distribution, strain, fracture resistance and mode of failure of root filled teeth. Method: The investigation was conducted by using 3D finite element analysis (FEA) and in-vitro tests. 3D models of a maxillary central incisor were generated: WFe, without ferrule; Fe1, 1.0 mm of ferrule; and Fe2, 2.0 mm of ferrule; restored with glass fiber post (Gfp) or cast post-and-core (Cpc); and metal crowns (Mc) or alumina-reinforced ceramic crowns (Cc). Each FE model was subjected to 100 N oblique loads. The results were evaluated by von Mises criterion and Principal maximum stress. One hundred and twenty bovine incisors were selected and divided into 12 treatment groups (n=10). Treatment variations were the same as used in finite element analysis. The teeth were loaded at a 135-degree angle, and the root strain was measured. Specimens were subsequently loaded until frac...

Objective: To evaluate the micropush-out bond strength influence of self-cured and dual-cured lut... more Objective: To evaluate the micropush-out bond strength influence of self-cured and dual-cured luting systems and degree of conversion these systems. Method: Forty single-rooted bovine teeth were root filled and prepared to receive fiberglass post Exacto nº 3 [Angelus]. The luting systems (LS) tested were (n=10): All Bond 2 (AB)/C&B (CB) [Bisco], Fusion Duralink (FD)/Cement-Post (CP) [Angelus], SingleBond 2 (SB)/Rely X ARC (ARC) [3M Espe] and Rely X U100 (U100) [3M Espe]. Two slices for cervical, middle and apical third of root were obtained. The slices were tested with micropush-out test (MBS) at a speed of 0.5 mm min¯¹. Degree of conversion (DC) was determined by Fourier transform infrared spectroscopy (FT-IR) (n=3). The MBS and DC values were analyzed using ANOVA and Tukey’s test (p < 0.05). Result: The table shows MBS (MPa) and DC mean (%) and standard deviations for experimental groups. Luting System Third - MBS (MPa) DC (%) Cervical Middle Apical AB/CB 12.0±7.1Aab 5.6±2.9Ba ...

Brazilian Dental Journal, 2015

Failures may occur in the connections of dental implants, especially in external hexagon (EH). Du... more Failures may occur in the connections of dental implants, especially in external hexagon (EH). Due to the deformations in this portion of implants, this study aimed to evaluate the levels of deformation of EH connections subjected to internal toque. Two types of implants were used: N group and S group. Torques of 0, 32, 45, 60 and 80 Ncm were applied to the N group, and torques of 0, 30, 40, 60 and infinite Ncm were applied to the S group implants. The internal distance (ID), internal area (IA) and external area (EA) of the EH were obtained from digital pictures, which were analyzed by a specific software. Statistical analysis was performed by the Scott-Knott test. The results showed that the higher the torque applied, the greater were the changes in the evaluated dimensions in both groups. In the S group, torque levels equal or greater than 40 Ncm and 30 Ncm caused greater deformation of EA and IA respectively, while in the N group, torque levels equal or greater than 60 Ncm and 32 Ncm caused greater deformation of EA and IA respectively. Levels of deformation were greater in the S group as compared with the N group. These findings suggest that the IA, EA and ID of the EH may be affected by different internal torque levels.

American journal of dentistry, 2015

To investigate the influence of a high elastic modulus material insert on the stress, shock absor... more To investigate the influence of a high elastic modulus material insert on the stress, shock absorption and displacement of mouthguards. Finite element models of a human maxillary central incisor with and without mouthguard were created based on cross-sectional CT-tomography. The mouthguard models had four designs: without insert, and middle, external, or palatal hard insert. The hard inserts had a relatively high elastic modulus when compared to the elastic modulus of ethylene vinyl acetate (EVA): 15 GPa versus 18 MPa. A non-linear dynamic impact analysis was performed in which a heavy rigid object hit the model at 1 m/s. Strain and stress (von Mises and critical modified von Mises) distributions and shock absorption during impact were calculated as well as the mouthguard displacement. The model without mouthguard had the highest stress values at the enamel and dentin structures in the tooth crown during the impact. It was concluded that the use of a mouthguard promoted lower stress...

Dental traumatology : official publication of International Association for Dental Traumatology, Jan 3, 2015

Custom-fitted mouthguards are devices used to decrease the likelihood of dental trauma. The aim o... more Custom-fitted mouthguards are devices used to decrease the likelihood of dental trauma. The aim of this study was to develop an experimental bovine dentoalveolar model with periodontal ligament to evaluate mouthguard shock absorption, and impact strain and stress behavior. A pendulum impact device was developed to perform the impact tests with two different impact materials (steel ball and baseball). Five bovine jaws were selected with standard age and dimensions. Six-mm mouthguards were made for the impact tests. The jaws were fixed in a pendulum device and impacts were performed from 90, 60, and 45° angles, with and without mouthguard. Strain gauges were attached at the palatal surface of the impacted tooth. The strain and shock absorption of the mouthguards was calculated and data were analyzed with 3-way anova and Tukey's test (α = 0.05). Two-dimensional finite element models were created based on the cross-section of the bovine dentoalveolar model used in the experiment. A ...

Brazilian Dental Journal, 2015

Despite several advantages associated with pre-fabricated glass-fiber posts, the coronal portion ... more Despite several advantages associated with pre-fabricated glass-fiber posts, the coronal portion of these posts must be cut to allow their use in various clinical situations. However, cutting the cemented post can generate stress on the bonding interface and affect the bond strength. The aim of this study was to investigate the effect the of fiber post cutting on the bond strength of root canals. Sixty bovine incisor roots were included in resin cylinders with simulated periodontal ligaments. Glass-fiber posts were luted using regular resin cement RelyX ARC (3M ESPE) or self-adhesive cement RelyX Unicem (3M ESPE). The posts were cut prior to cementation, immediately after luting or after building up the core (n=10). After storage for 24 h, the samples were cut and subject to push-out testing using a mechanical testing machine (EMIC DL 2000). Data were analyzed using two-way ANOVA (resin cement x moment of post cutting) and Tukey's post hoc test (α=0.05). The moment of fiber post cutting did not affect the bond strength when Unicem was used. However, the bond strength was reduced when ARC was used and when the post was cut immediately. In conclusion, the moment of fiber post cutting may affect the retention of root canal posts when a regular resin cement is used.

Objective: To evaluate the biomechanical behavior of endodontically treated anterior teeth by str... more Objective: To evaluate the biomechanical behavior of endodontically treated anterior teeth by strain measurement, finite element analysis (FEA), and fracture resistance by varying the presence of ferrule and length of different endodontic posts. Methods: Eighty bovine incisor roots were selected and divided into 2 groups (n = 40): with ferrule of 2.0 mm, with no ferrule. These groups were divided into 4 subgroups (n = 10) varying the endodontic posts: fiberglass posts and cast post-and-cores, in lengths of 12 and 7 mm. All roots were restored with metal crowns. Five specimens from each group were subjected to strain-gage measurement. The fracture resistance was measured in mechanical testing machine with application of tangential load at an angle of 135 ° with the long axis of the tooth. Data were submitted to factorial analysis of variance. The failure pattern was analyzed in accordance with the degree of damage to the tooth structure.Tridimensional models of each experimental grou...

Objective: The aim of this study was to quantify the influence of direct and indirect restorative... more Objective: The aim of this study was to quantify the influence of direct and indirect restorative techniques on stress distribution pattern of maxillary premolar by 3D finite element method. Method: One intact maxillary premolar was selected and the enamel/root boundaries were scanned using a contact-scanner (LPX-400, Roland, USA) in which 3D-stereolithography files were obtained. On the next step, the enamel and dentin were sequentially degraded with HCl-2% acid solution. The dentin/pulp boundaries were scanned. These files were exported to Bio-CAD software (Rhino3D). The volumes of each structure were obtained by NURBS surfaces association. In this software, the periodontal-ligament simulation was made. All volumes were exported to Finite Element software packages (NeiNastran and FEMAP). The meshes of each structure were created with tetrahedral nodes, according to mechanical properties obtained by literature review. A linear-static-isotropic model and boundary conditions were cre...

The journal of contemporary dental practice, 2007

The aim of this article is to describe a step-by-step protocol for emergency care of a patient wi... more The aim of this article is to describe a step-by-step protocol for emergency care of a patient with a dentoalveolar injury in the anterior region of the mouth as well as the fabrication of a mouthguard to prevent future trauma. Dental trauma is one of the most serious oral health problems in active children and adolescents. Care of traumatized patients requires immediate initial emergency treatment followed by integrated procedures to restore damaged oral structures along with a subsequent trauma prevention strategy. Dentoalveolar injuries in the anterior region of the mouth are often characterized by tooth avulsion and coronal fracture. They are managed using procedures such as dental splinting, endodontic therapy with its unique characteristics, and restorative techniques to re-establish function and esthetics as well as protective mouthguards. A 16-year-old male presented with avulsion of his maxillary central incisors as a result of a direct, unintentional impact with an opponen...

Acta odontológica latinoamericana : AOL, 2012

This study evaluated the effect of adhesive application only to enamel on the marginal microleaka... more This study evaluated the effect of adhesive application only to enamel on the marginal microleakage of composite resin restorations performed with different adhesive systems. Standardized cylinder-shaped cavities were prepared on the buccal surface of eighty bovine incisors. Two etch-and-rinse (Adper Scotchbond Multi-purpose [3M ESPE, St. Paul, MN USA] and Adper Single Bond 2 [3M ESPE]) and two self-etching (Clearfil SE Bond [Kuraray, Osaka, Japan] and Adper Prompt [3M ESPE]) adhesive systems were evaluated. The adhesives were applied only to enamel or to both dentin and enamel. After adhesive light-activation, the cavities were restored with composite resin. The samples were coated with two layers of nail polish, except an area of 1-mm wide around of the restoration, and immersed in a methylene blue solution. Afterwards, the specimens were ground in order to obtain powder which was immersed in absolute alcohol. The solutions were centrifuged and the supernatant was analyzed using a...

Brazilian oral research

The aim of this study was to evaluate the effect of parallel and tapered threaded post placement ... more The aim of this study was to evaluate the effect of parallel and tapered threaded post placement on the strain and stress distribution of endodontically treated teeth. Fifteen bovine incisors were sectioned 15 mm from their apices, endodontically treated, and divided into three groups (n=5) according to three different threaded posts: parallel threaded post (Radix-Anker, RA); tapered threaded post (Euro-Post, EP) and tapered threaded post (Reforpost II, RII). A strain-gauge was fixed on the proximal surface perpendicular to the long root axis, 2 mm from the cervical limit. Strain generated during post placement was recorded and compared using one-way ANOVA and Tukey's test (α=.05). A scanning electron microscope was used to examine the longitudinal root sections. Stress was evaluated for each group in a two-dimensional finite element analysis. The models were meshed with tetrahedron elements and loaded with 2 N at an angle of 135° to the lingual face. The equivalent Von Mises st...

Journal of Endodontics, 2014

Introduction: The aim of this study was to evaluate the influence of a ferrule, post system, and ... more Introduction: The aim of this study was to evaluate the influence of a ferrule, post system, and length on the stress distribution of weakened root-filled teeth. Methods: The investigation was conducted by using 3-dimensional (3D) finite element analysis. A sound tooth and 8 3D models of a weakened root-filled central incisor were generated using computer-aided design/ computer-aided manufacturing software. The models were created without a ferrule and with a 2.0-mm ferrule, restored with a relined glass fiber post or a cast post and core (Cpc), and 12.0-and 7.0-mm post lengths. Each 3D model was imported using *.STEP files to the finite element software for mesh generation. The models were subjected to 100-N oblique loading at the palatal surface, and the results were evaluated by von Mises criterion and maximum principal stress distribution. Results: Finite element analysis showed that the Cpc models showed elevated stress levels in the root canal regardless of the presence of a ferrule. Relined glass fiber post models showed homogeneous stress distribution to the dentin external surface similar to the sound tooth model. Without a ferrule, Cpc with a 7-or 12mm length promoted high levels of tensile stress inside the root canal. Conclusions: Ferrule presence promoted more satisfactory stress distribution to the roots. Post length influenced the stress distribution only for the models restored with a cast post and core. High levels of tensile stress inside the root canals were verified with a cast post and core, which should be avoided to rehabilitate weakened roots, mainly in the absence of a ferrule. (J Endod 2014;-:1-5)

International Journal of Experimental Dental Science, 2012

This study evaluated the effect of adhesive application only to enamel on the gap formation of co... more This study evaluated the effect of adhesive application only to enamel on the gap formation of composite resin restorations performed with different adhesive systems and submitted to mechanical cycling. Standardized cylinder-shaped cavities were prepared on the buccal surface of 60 bovine incisors. Two etchand-rinse [Adper Scotchbond Multi-purpose (3M ESPE, St. Paul, MN, USA) and Adper Single Bond 2 (3M ESPE)] and one selfetching [Clearfil SE Bond (Kuraray, Osaka, Japan)] adhesive systems were evaluated. The adhesives were applied only to enamel or to both dentin and enamel. After adhesive light activation, the cavities were restored with composite resin. The restorations were finished and polished; the marginal adaptation was analyzed using scanning electronic microscopy (SEM, 500× magnification) in low-vacuum mode. After the first evaluation, the samples were submitted to mechanical cycling (300,000 cycles of 80 kN and 1.5 Hz) and a new evaluation was performed. There was observed any gap for all experimental conditions before and after mechanical cycling. Bonding to dentin does not alter the marginal adaptation of composite restorations.

Journal of Prosthodontics, 2011

Purpose: This in vitro study investigated the null hypothesis that metal-free crowns induce fract... more Purpose: This in vitro study investigated the null hypothesis that metal-free crowns induce fracture loads and mechanical behavior similar to metal ceramic systems and to study the fracture pattern of ceramic crowns under compressive loads using finite element and fractography analyses. Materials and Methods: Six groups (n = 8) with crowns from different systems were compared: conventional metal ceramic (Noritake) (CMC); modified metal ceramic (Noritake) (MMC); lithium disilicate-reinforced ceramic (IPS Empress II) (EMP); leucite-reinforced ceramic (Cergogold) (CERG); leucite fluoride-apatite reinforced ceramic (IPS d.Sign) (SIGN); and polymer crowns (Targis) (TARG). Standardized crown preparations were performed on bovine roots containing NiCr metal dowels and resin cores. Crowns were fabricated using the ceramics listed, cemented with dual-cure resin cement, and submitted to compressive loads in a mechanical testing machine at a 0.5-mm/min crosshead speed. Data were submitted to one-way ANOVA and Tukey tests, and fractured specimens were visually inspected under a stereomicroscope (20×) to determine the type of fracture. Maximum principal stress (MPS) distributions were calculated using finite element analysis, and fracture origin and the correlation with the fracture type were determined using fractography. Results: Mean values of fracture resistance (N) for all groups were: CMC: 1383 ± 298 (a); MMC: 1691 ± 236 (a); EMP: 657 ± 153 (b); CERG: 546 ± 149 (bc); SIGN: 443 ± 126 (c); TARG: 749 ± 113 (b). Statistical results showed significant differences among groups (p < 0.05) represented by different lowercase letters. Metal ceramic crowns presented fracture loads significantly higher than the others. Ceramic specimens presented high incidence of fractures involving either the core or the tooth, and all fractures of polymer crown specimens involved the tooth in a catastrophic way. Based on stress and fractographic analyses it was determined that fracture occurred from the occlusal to the cervical direction. Conclusions: Within the limitations of this study, the results indicated that the use of ceramic and polymer crowns without a core reinforcement should be carefully evaluated before clinical use due to the high incidence of failure with tooth involvement. This mainly occurred for the polymer crown group, although the fracture load was higher than normal occlusal forces. High tensile stress concentrations were found around and between the occlusal loading points. Fractographic analysis indicated fracture originating from the load point and propagating from the occlusal surface toward the cervical area, which is the opposite direction of that observed in clinical situations.

Journal of Prosthodontics, 2010

To test the hypothesis that the type of cement used for fixation of cast doweland-cores might inf... more To test the hypothesis that the type of cement used for fixation of cast doweland-cores might influence fracture resistance, fracture mode, and stress distribution of single-rooted teeth restored with this class of metallic dowels. Materials and Methods: The coronal portion was removed from 40 bovine incisors, leaving a 15 mm root. After endodontic treatment and standardized root canal relief at 10 mm, specimens were embedded in polystyrene resin, and the periodontal ligament was simulated with polyether impression material. The specimens were randomly divided into four groups (n = 10), and restored with Cu-Al cast dowel-and-cores cemented with one of four options: conventional glass ionomer cement (GI); resinmodified glass ionomer cement (GR); dual-cure resin cement (RC); or zinc-phosphate cement (ZP). Sequentially, fracture resistance of the specimens was tested with a tangential load at a 135 • angle with a 0.5 mm/min crosshead speed. Data were analyzed using one-way analysis of variance (ANOVA) and the Fisher test. Two-dimensional finite element analysis (2D-FEA) was then performed with representative models of each group simulating a 100 μm cement layer. Results were analyzed based on von Mises stress distribution criteria. Results: The mean fracture resistance values were (in N): RC, 838.2 ± 135.9; GI, 772.4 ± 169.8; GR, 613.4 ± 157.5; ZP, 643.6 ± 106.7. FEA revealed that RC and GR presented lower stress values than ZP and GI. The higher stress concentration was coincident with more catastrophic failures, and consequently, with lower fracture resistance values. Conclusions: The type of cement influenced fracture resistance, failure mode, and stress distribution on teeth restored with cast dowel-and-cores.

Journal of Prosthodontics, 2008

The aim of this study was to evaluate the effect of endodontic and restorative treatment on the f... more The aim of this study was to evaluate the effect of endodontic and restorative treatment on the fracture resistance of posterior teeth. Materials and Methods: Fifty intact premolars were selected and randomly placed into five groups (n = 10): G1, intact teeth (control); G2, mesial-occlusal-distal (MOD) preparation; G3, MOD preparation restored with composite resin (Z-250, 3M ESPE); G4, MOD preparation and endodontic treatment; and G5, MOD preparation, endodontic treatment, and composite resin restoration. The specimens were submitted to an axial compression load in a mechanical test machine (EMIC), at a speed of 0.5 mm/min. Fracture patterns were analyzed at four levels. Five 2D numerical models were created by Ansys 10.0 for finite element analysis (FEA). Results: Mean values of compressive strength for all groups were (Kgf): G1 (83.6 ± 25.4); G2 (52.7 ± 20.2); G3 (82.1 ± 24.9); G4 (40.2 ± 14.2); G5 (64.5 ± 18.1). Statistical analysis (ANOVA and Tukey's test) showed that fracture resistance of G1 was significantly higher than that of G5, G2, and G4. Resistance of G3 was also higher than that of G2 and G4. Results showed that the tooth resistance is completely maintained when MOD preparation is restored with composite resin and partially recovered when MOD preparation associated with an endodontic access is restored in the same way. The endodontic treatment and composite resin restoration influenced stress distribution in the dental structure. Conclusions: Composite resin restoration plays an important role in recovering tooth strength. With regard to fracture mode, restoration and endodontic treatment increased the incidence of periodontal involvement, which was demonstrated by association with the finite element mechanical test method.

The Journal of Prosthetic Dentistry, 2008